Shear bond strength of universal adhesives to human enamel and dentin

OBJECTIVE

The composition of universal adhesives is highly diverse. The purpose of this in vitro study was to compare the shear bond strength of a composite with five different universal adhesives to human enamel and dentin.

MATERIALS AND METHODS

The shear bond strength of a composite (G-aenial Universal Injectable) to human enamel and dentin was tested in selective enamel etching mode before and after thermocyclic aging (10,000 cycles) using five different universal adhesive systems (Adhese Universal VivaPen, Clearfil Universal Bond Quick, G-Premio Bond, Prime&Bond active, and Scotchbond Universal Plus). Two-bottle systems (OptiBond FL and G2-Bond Universal) were used as control. Scanning electron microscopy was conducted of the bonding interface.

RESULTS

Significant differences in shear bond strength values were found among the five evaluated universal adhesives. Lowest shear bond strength values were observed for 2-hydroxyethylmethacrylate (HEMA)-free systems. Thermocyclic aging did not significantly reduce shear bond strength values indicating that the initial bond remains stable.

CONCLUSIONS

The clinical use of universal adhesives Adhese Universal VivaPen, Clearfil Universal Bond Quick, and Scotchbond Universal Plus can be encouraged as they provided comparable or even better shear bond strength values than the two-bottle controls.

CLINICAL SIGNIFICANCE

Universal adhesives that were developed for the same indication and approved for clinical use demonstrated variety in shear bond strength values. When applied in the selective enamel etching mode, a stable bond can be expected from adhesives containing HEMA and monomers with phosphate groups.

Friction and wear behavior of a mechanical oscillating strip system used for interproximal enamel reduction: a quantitative and qualitative scanning electronic microscope evaluation

OBJECTIVES

To evaluate wear and friction properties of oscillating strips in order to validate the importance of a standardized interproximal enamel reduction (IPR) sequence to preserve their efficiency and lifetime.

MATERIALS AND METHODS

Fifteen complete oscillating IPR sequences were tested by means of tribological tests (Linear Reciprocating Tribometer, C.S.M. Instruments, Peseaux, Switzerland). Fifteen single 0.2-mm metallic strips underwent a long continuous cycle of 240 minutes. Strip surface roughness and waviness measurements were assessed by means of a contact probe surface profiler (TalySurf CLI 2000; Taylor Hobson, Leicester, UK) and TayMap software. Statistical analysis was performed with independent-samples t-test. Significance was at the P < .05 level. Scanning electronic microscopy analysis of strip surfaces was conducted with an FEI Quanta 200 (Hillsboro, Ore) in high vacuum at 30.00 kV.

RESULTS

Resin strips revealed a significant reduction in surface roughness (Ra, Rt, RDq) and a significant increase in waviness parameters (Wa, Wt). Rt and RDq values significantly decreased upon use of the metallic strips. Significantly higher values of Wa (+ 2.84 µm) and Wt (+0.1 µm) were observed only for the 0.2-mm metallic strips. Higher friction values were observed when the metallic strips were tested singularly rather than within the entire sequence. Lower Ra and Rt values were revealed when 0.2-mm metallic strips were tested up to 240 minutes.

CONCLUSIONS

The application of a standardized oscillating sequence allows for more efficient wear performance of the strips with a significant impact on their abrasive power and lifetime.

Diagnostic accuracy of clinical signs to detect erosive tooth wear in its early phase

BACKGROUND

Agreement exists about most of the clinical features of erosive tooth wear, though no evidence supports their validity in diagnosing the condition.

OBJECTIVE

This study aimed to determine the accuracy of clinical signs for diagnosing erosive tooth wear in a young adult general population.

METHODS

We conducted a cross-sectional study of dental students. In the first session, two examiners independently determined the presence of erosive tooth wear based on glazed enamel surfaces, morphological changes on non-occlusal surfaces, flattening of convex areas, or any type of concavity. In the second session, one examiner recorded the presence of clinical signs according to the Tooth Wear Evaluation System. The diagnostic accuracy of each clinical sign, both alone and combined, was assessed by calculating their sensitivity and specificity for detecting erosive tooth wear and performing multivariate logistic regression models.

RESULTS

Of the 147 participants (78 women and 69 men; median age, 22 years) we included, 76.2% had erosive tooth wear. The single clinical signs with greatest balance between the sensitivity and specificity were 'convex areas flatten' (63% and 71%, respectively) and 'dull surface' (47% and 89%, respectively). Multivariate logistic regression revealed that 'preservation of the enamel cuff' (odds ratio, 22) and the combination of 'smooth silky shining, silky glazed appearance, and dull surface' (odds ratio, 68) had the best predictive values.

CONCLUSIONS

The most accurate clinical signs for detecting early erosive tooth wear were dull surface, flattened convex areas and preservation of the enamel cuff.

Use of artificial intelligence software in dental education: A study on assisted proximal caries assessment in bitewing radiographs

INTRODUCTION

Teaching of dental caries diagnostics is an essential part of dental education. Diagnosing proximal caries is a challenging task, and automated systems applying artificial intelligence (AI) have been introduced to assist in this respect. Thus, the implementation of AI for teaching purposes may be considered. The aim of this study was to assess the impact of an AI software on students' ability to detect enamel-only proximal caries in bitewing radiographs (BWs) and to assess whether proximal tooth overlap interferes with caries detection.

MATERIALS AND METHODS

The study included 74 dental students randomly allocated to either a test or control group. At two sessions, both groups assessed proximal enamel caries in BWs. At the first session, the test group registered caries in 25 BWs using AI software (AssistDent®) and the control group without using AI. One month later, both groups detected caries in another 25 BWs in a clinical setup without using the software. The student's registrations were compared with a reference standard. Positive agreement (caries) and negative agreement (no caries) were calculated, and t-tests were applied to assess whether the test and control groups performed differently. Moreover, t-tests were applied to test whether proximal overlap interfered with caries registration.

RESULTS

At the first and second sessions, 56 and 52 tooth surfaces, respectively, were detected with enamel-only caries according to the reference standard. At session 1, no significant difference between the control (48%) and the test (42%) group was found for positive agreement (p = .08), whereas the negative agreement was higher for the test group (86% vs. 80%; p = .02). At session 2, there was no significant difference between the groups. The test group improved for positive agreement from session 1 to session 2 (p < .001), while the control group improved for negative agreement (p < .001). Thirty-eight per cent of the tooth surfaces overlapped, and the mean positive agreement and negative agreement were significantly lower for overlapping surfaces than non-overlapping surfaces (p < .001) in both groups.

CONCLUSION

Training with the AI software did not impact on dental students' ability to detect proximal enamel caries in bitewing radiographs although the positive agreement improved over time. It was revealed that proximal tooth overlap interfered with caries detection.

Association between molar hypomineralization, genes involved in enamel development, and medication in early childhood: A preliminary study

BACKGROUND

Molar hypomineralization (MH) is defined as a multifactorial condition, and thus, its presence may be defined by interactions between environmental and genetic factors.

AIM

To evaluate the association between MH, genes involved in enamel development, and the use of medication during pregnancy in early childhood.

DESIGN

One hundred and eighteen children, 54 with and 64 without MH, were studied. The data collected included demographics, socioeconomic data, and the medical history of mothers and children. Genomic DNA was collected from saliva. Genetic polymorphisms in ameloblastin (AMBN; rs4694075), enamelin (ENAM; rs3796704, rs7664896), and kallikrein (KLK4; rs2235091) were evaluated. These genes were analyzed by real-time polymerase chain reaction using TaqMan chemistry. The software PLINK was used to compare allele and genotype distributions of the groups and to assess the interaction between environmental variables and genotypes (p < .05).

RESULTS

The variant allele KLK4 rs2235091 was associated with MH in some children (odds ratio [OR]: 3.75; 95% confidence interval [CI] = 1.65-7.81; p = .001). Taking medications in the first 4 years of life was also associated with MH (OR: 2.94; 95% CI = 1.02-6.04; p = .041) and specifically in association with polymorphisms in ENAM, AMBN, and KLK4 (p < .05). The use of medications during pregnancy was not associated with MH (OR: 1.37; 95% CI = 0.593-3.18; p = .458).

CONCLUSION

The results of this study suggest that taking medication in the postnatal period appears to contribute to the etiology of MH in some evaluated children. There may be a possible genetic influence of polymorphisms in the KLK4 gene with this condition.

Influence of coating dental enamel with a TiF4-loaded polymeric primer on the adverse effects caused by a bleaching gel with 35% H2O2

OBJECTIVE

To evaluate whether coating enamel with a polymeric primer (PPol) containing titanium tetrafluoride (TiF4) before applying a bleaching gel with 35% H2O2 (35% BG) increases esthetic efficacy, prevents changes in morphology and hardness of enamel, as well as reduces the cytotoxicity from conventional in-office bleaching.

MATERIALS AND METHODS

Standardized enamel/dentin discs were stained and bleached for 45 min (one session) with 35% BG. Groups 2TiF4, 6TiF4, and 10TiF4 received the gel on the enamel previously coated with PPol containing 2 mg/mL, 6 mg/mL, or 10 mg/mL, respectively. No treatment or application of 35% BG directly on enamel were used as negative control (NC), and positive control (PC), respectively. UV-reflectance spectrophotometry (CIE L*a*b* system, ΔE00, and ΔWI, n = 8) determined the bleaching efficacy of treatments. Enamel microhardness (Knoop, n = 8), morphology, and composition (SEM/EDS, n = 4) were also evaluated. Enamel/dentin discs adapted to artificial pulp chambers (n = 8) were used for trans-amelodentinal cytotoxicity tests. Following the treatments, the extracts (culture medium + bleaching gel components diffused through the discs) were collected and applied to odontoblast-like MDPC-23 cells, which were assessed concerning their viability (alamarBlue, n = 8; Live/Dead, n = 4), oxidative stress (n = 8), and morphology (SEM). The amount of H2O2 in the extracts was also determined (leuco crystal violet/peroxidase, n = 8). The numerical data underwent one-criterion variance analysis (one-way ANOVA), followed by Tukey's test, at a 5% significance level.

RESULTS

Regarding the ΔE00, no difference was observed among groups 2TiF4, 6TiF4, and PC (p > 0.05). The ΔWI was similar between groups 2TiF4 and PC (p > 0.05). The ΔWI of group 6TiF4 was superior to PC (p < 0.05), and group 10TiF4 achieved the highest ΔE00 and ΔWI values (p < 0.05). Besides limiting enamel microstructural changes compared to PC, group 10TiF4 significantly increased the hardness of this mineralized dental tissue. The highest cellular viability occurred in 10TiF4 compared to the other bleached groups (p < 0.05). Trans-amelodentinal H2O2 diffusion decreased in groups 2TiF4, 6TiF4, and 10TiF4 in comparison with PC (p < 0.05).

CONCLUSION

Coating enamel with a PPol containing TiF4 before applying a 35% BG may increase enamel microhardness and esthetic efficacy and reduce the trans-amelodentinal cytotoxicity of conventional in-office tooth bleaching. The PPol containing 10 mg/mL of TiF4 promoted the best outcomes.

Human-like enamel growth in Homo naledi

OBJECTIVES

A modern pattern (rate and duration) of dental development occurs relatively recently during human evolution. Given the temporal overlap of Homo naledi with the first appearance of fossil Homo sapiens in Africa, this small-bodied and small-brained hominin presents an opportunity to elucidate the evolution of enamel growth in the hominin clade. Here we conduct the first histological study of two permanent mandibular canines and one permanent maxillary first molar, representing three individuals attributed to H. naledi. We reconstruct the rate and duration of enamel growth and compare these findings to those reported for other fossil hominins and recent humans.

MATERIALS AND METHODS

Thin sections of each tooth were produced using standard histological methods. Daily and longer period incremental markings were measured to reconstruct enamel secretion and extension rates, Retzius periodicity, canine crown and molar cusp formation time.

RESULTS

Daily enamel secretion rates overlapped with those from recent hominins. Canine crown formation time is similar to that observed in recent Europeans but is longer than canine formation times reported for most other hominins including Australopithecus and H. neanderthalensis. The extended period of canine formation appears to be due to a relatively tall enamel crown and a sustained slow rate of enamel extension in the cervical portion of the crown. A Retzius periodicity of 11 days for the canines, and nine days for the molar, in H. naledi parallel results found in recent humans. An 11-day periodicity has not been reported for Late Pleistocene Homo (H. erectus, H. neanderthalensis) and is rarely found in Australopithecus and Paranthropus species.

DISCUSSION

Enamel growth of H. naledi is most similar to recent humans though comparative data are limited for most fossil hominin species. The high Retzius periodicity values do not follow expectations for a small-brained hominin.

Effect of different brushing parameters on erosive tooth wear in primary bovine enamel and dentin

This in-vitro study aimed to analyse the effect of brushing and different brushing parameters (kind of toothpaste, kind of toothbrush, brushing force) on erosive tooth wear of primary bovine enamel and dentin. Specimens were prepared from primary bovine enamel or dentin (each group n = 12) and cyclically eroded (6 × 60 s/d, citric acid, pH 2.4) and brushed with children's toothbrushes (2 × 15 s/d) over 5 days. The brushing parameters under investigation were: toothpaste (fluoridated, fluoride-free), toothbrush (manual; rotating-oscillating and sonic, each at two different activation modes) and brushing force (1 N, 2 N). Specimens that were only eroded and not brushed served as controls. Enamel and dentin wear was quantified using widefield confocal microscopy. Statistical analysis was performed using three- and one-way ANOVAs followed by Scheffe's (enamel) or Tamhane's (dentin) post-hoc tests (p < 0.05). Brushing with the fluoridated toothpaste was able to significantly reduce erosive wear in enamel (by 15 to 37%, 6 of 10 groups) and in dentin (by 58 to 72%, all groups), while brushing with the fluoride-free toothpaste was not different from the controls. Considering the kind of toothpaste and brushing force, slight differences between the toothbrushes were observed in enamel, but not in dentin. Within the same toothbrush and activation mode, almost no differences between 1 and 2 N brushing force were detected. In conclusion, erosive tooth wear on primary bovine dental hard tissue mainly depends on the kind of toothpaste, rather than on the kind of toothbrush and the brushing force.

Bayesian modeling of spatially differentiated multivariate enamel defects of the children's primary maxillary central incisor teeth

BACKGROUND

The analysis of dental caries has been a major focus of recent work on modeling dental defect data. While a dental caries focus is of major importance in dental research, the examination of developmental defects which could also contribute at an early stage of dental caries formation, is also of potential interest. This paper proposes a set of methods which address the appearance of different combinations of defects across different tooth regions. In our modeling we assess the linkages between tooth region development and both the type of defect and associations with etiological predictors of the defects which could be influential at different times during the tooth crown development.

METHODS

We develop different hierarchical model formulations under the Bayesian paradigm to assess exposures during primary central incisor (PMCI) tooth development and PMCI defects. We evaluate the Bayesian hierarchical models under various simulation scenarios to compare their performance with both simulated dental defect data and real data from a motivating application.

RESULTS

The proposed model provides inference on identifying a subset of etiological predictors of an individual defect accounting for the correlation between tooth regions and on identifying a subset of etiological predictors for the joint effect of defects. Furthermore, the model provides inference on the correlation between the regions of the teeth as well as between the joint effect of the developmental enamel defects and dental caries. Simulation results show that the proposed model consistently yields steady inferences in identifying etiological biomarkers associated with the outcome of localized developmental enamel defects and dental caries under varying simulation scenarios as deemed by small mean square error (MSE) when comparing the simulation results to real application results.

CONCLUSION

We evaluate the proposed model under varying simulation scenarios to develop a model for multivariate dental defects and dental caries assuming a flexible covariance structure that can handle regional and joint effects. The proposed model shed new light on methods for capturing inclusive predictors in different multivariate joint models under the same covariance structure and provides a natural extension to a nested hierarchical model.

Enamel changes of bleached teeth following application of an experimental combination of chitosan-bioactive glass

BACKGROUND

Considering the extensive use of bleaching agents and the occurrence of side effects such as enamel demineralization, this study aimed to assess the enamel changes of bleached teeth following the experimental application of chitosan-bioactive glass (CH-BG).

METHODS

In this in vitro study, CH-BG (containing 66% BG) was synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Thirty sound human premolars were bleached with 40% hydrogen peroxide, and the weight% of calcium and phosphorus elements of the buccal enamel surface was quantified before and after bleaching by scanning electron microscopy/ energy-dispersive X-ray spectroscopy (SEM, EDX). Depending on the surface treatment of the enamel surface, the specimens were divided into three groups (n = 10): control (no treatment), MI Paste (MI), and CH-BG. Then the specimens were stored in artificial saliva for 14 days. The SEM/EDX analyses were performed again on the enamel surface. Data were analyzed by one-way ANOVA and Tukey's test and a p-value of < 0.05 was considered statistically significant.

RESULTS

In all groups, the weight% of calcium and phosphorus elements of enamel decreased after bleaching; this reduction was significant for phosphorus (p < 0.05) and insignificant for calcium (p > 0.05). After 14 days of remineralization, the weight% of both calcium and phosphorus elements was significantly higher compared to their bleached counterparts in both MI and CH-BG groups (p < 0.05). Following the remineralization process, the difference between MI and CH-BG groups was not significant (p > 0.05) but both had a significant difference with the control group in this regard (p < 0.05).

CONCLUSIONS

The synthesized CH-BG compound showed an efficacy comparable to that of MI Paste for enamel remineralization of bleached teeth.

The prevalence of developmental defects of enamel in people with cystic fibrosis: a systematic review

BACKGROUND

Oral health impacts systemic health, individual well-being, and quality of life. It is important to identify conditions that may exacerbate oral disease to aid public health and policy development and promote targeted patient treatment strategies. Developmental defects can increase an individual's risk of dental caries, hypersensitivity, premature tooth wear, erosion, and poor aesthetics. As part of an ongoing study assessing oral health in adults with cystic fibrosis at Cork University Dental School and Hospital, a systematic review of available literature was conducted to assess the prevalence of enamel defects in people with cystic fibrosis.

AIMS

To critically evaluate the literature to determine if the prevalence of developmental defects of enamel is higher in people with cystic fibrosis (PwCF).

METHODS

Data Sources: Three online databases were searched Embase, Scopus, and Web of Science Core Collection. Studies that examined an association between cystic fibrosis and developmental defects of enamel were included in this systematic review.

RESULTS

The initial search identified 116 publications from the following databases Embase, Web of Science Core Collection, and Scopus. Eleven studies were included for qualitative analysis. Nine studies concluded that PwCF had a higher prevalence of enamel defects than control people and one study found no difference in cystic fibrosis (CF) status. All studies had a risk of bias that may influence study results and their interpretation.

CONCLUSIONS

The results of the systematic review show a consistent pattern that PwCF have a higher prevalence of DDE than people without CF. Genetic dysfunction, chronic systemic infections, and long-term antibiotic use are possible aetiological causes. This review highlights the need for future studies to investigate if DDEs are caused by the underlying CFTR mutation or as a consequence of disease manifestations and/or management.

The erosive effect of pomegranate juice on enamel: An in vitro study

AIM

Dental erosion is a chemical-mechanical process that leads to the loss of dental hard tissues. This study aimed to investigate the effect of pomegranate juice on the enamel.

METHODS

Enamel blocks were randomly divided into three groups: deionized water, cola, and pomegranate juice. The blocks were immersed in the solutions four times a day for 14 days, and stored in artificial saliva for the remaining period. The surface hardness was measured on days 7 and 14. The surface structures of the demineralized blocks were observed via scanning electron microscopy (SEM), and the depth of demineralization was observed via confocal laser scanning microscopy (CLSM). The pH, calcium, and phosphorus levels of the three solutions were analyzed.

RESULTS

The microhardness values of the blocks in the pomegranate juice and cola groups decreased with the increase in the demineralization time. The blocks in the pomegranate juice group exhibited large fractures in the enamel column, whereas those in the cola group had pitted enamels with destruction of the interstitial enamel column. Compared with cola group, fluorescent penetration increased in pomegranate juice (P < 0.01). The pH of cola (2.32 ± 0.09) was lower than that of pomegranate juice (3.16 ± 0.16). Furthermore, the calcium content in pomegranate juice was significantly higher than that in cola (P < 0.01). Alternatively, the concentration of phosphorous in cola was significantly higher than that in pomegranate juice (P < 0.01).

CONCLUSION

These findings indicate that pomegranate juice can cause enamel demineralization with an erosive potential comparable to that of cola.

Cervical enamel projections from a periodontal perspective: A scoping review

Cervical enamel projections (CEPs) represent a unique developmental and anatomical anomaly wherein the enamel structure extends apically beyond the cemento-enamel junction of the tooth. In this scoping review, the existing literature on CEPs was evaluated to delineate their characteristics, prevalence, predilection for specific teeth and surfaces, clinical significance, and management approaches. Searches were conducted on MEDLINE (PubMed), Cochrane Library, and Embase databases using the keywords "enamel projection(s)" or "ectopic enamel." In total, 24 studies meeting inclusion criteria were included in the review. The prevalence of CEPs varied widely (8.3%-85.1%), predominantly manifesting as grade I or grade III. Mandibular first and second molars exhibited a higher incidence of CEPs, with a notable predilection for buccal surfaces. The consensus in most studies was that CEPs are associated with localized periodontal diseases. Recommendations inclined toward the removal of ectopic enamel during periodontal surgery to enhance periodontal attachment formation. However, decision-making should involve careful consideration of the benefits and drawbacks based on individual circumstances.

Effect of antioxidants on adhesive bond strength to bleached enamel

OBJECTIVE

To evaluate the influence of antioxidants (ATX) resveratrol, winter's bark, green tea and yerba mate on the bond strength between bleached enamel and the nanohybrid composite resin.

METHODOLOGY

Bovine incisor crowns (n = 132) were randomly divided into 22 groups (n = 6) according to the application times (5, 10, 15, 30, and 60 min) of each antioxidant. Teeth restored without previous bleaching or ATX constituted the non-bleached control group (NB Ctrl) (n = 6), and teeth restored after bleaching and without ATX represented the bleached control group (B Ctrl) (n = 6). The 35 % hydrogen peroxide was applied for 45 min (3 application of 15 min) to the buccal enamel surface. ATX was used after bleaching for the specified time of each group and removed with air-water spray. The enamel was etched with 37 % phosphoric acid (30 s) and rinsed with air-water spray. The adhesive resin was applied to the enamel dry surface. Teeth were restored using 1 mm composite resin increments (10 × 10 × 3 mm) and sectioned in test specimens of 6 mm in length and 1 mm2 in cross-sectional area submitted to microtensile bond strength test (0.5 mm/min). The load (N) at failure was recorded, and the bond strength (σt) was calculated (MPa). The fracture area was analyzed under optical microscopy, and failures were classified as cohesive, mixed, or adhesive. Data was evaluated by Kruskal-Wallis and Dunn tests (p ≤ 0.05).

RESULTS

B Ctrl group presented lower σt than NB Ctrl (p < 0.001). Applying resveratrol for 5 or 10 min, winter's bark for 10 or 15 min, green tea for less than 15 min, and yerba mate for 15 min provided similar σt between bleached enamel and nanohybrid composite to the control group.

CONCLUSION

Restorative procedures performed immediately after tooth bleaching compromises adhesion. Experimental antioxidants applied to bleached enamel can increase the immediate bond strength of restorations performed directly after bleaching, with similar values to those observed in unbleached enamel.

CLINICAL SIGNIFICANCE

This study presents promising results to support the use of antioxidants on the recently bleached enamel to allow adhesive tooth restorations. The immediate bonding obtained using antioxidants was similar to the one achieved in non-bleached enamel in brief application times. Green tea extract and resveratrol were able to restore the bond strength to bleached enamel in a short application time of 5 min. The reduction in the required application time holds the potential to decrease the overall duration of the clinical section, offering clinical advantages and improving the feasibility of using antioxidants on the bleached enamel prior to adhesive procedures.

Insight into structural and chemical profile / composition of powdered enamel and dentine in different types of permanent human teeth

Research on the structure and chemical composition of dental tissues allows for the optimisation of materials used in the treatment and care of teeth. Understanding pathological processes occurring in dental tissues and their reactions to various substances, including dental materials, are crucial for the development of new dental technologies. The aim of the study was to check the similarities in the chemical and morphological structure of enamel and dentine powders in various groups of permanent teeth, as well as differential chemical analysis for both grinded tissues tested. The extracted non-carious and non-pathological human permanent teeth were divided into four groups: incisors, canines, premolars and molars. Each tooth was sectioned to thick slices. Enamel and dentine were mechanically separated and ground in an agate mortar and pestle. FT-Raman and FTIR spectroscopy methods were used for the analysis of biological tissues. SEM method was applied to visualise hard dental tissues structures present on the surface and within the particles. The morphological structures were the same within the analysed tissues and did not depend on the analysed group of teeth. A comparison of the mineral-to-organic ratios of enamel and dentine in each tooth group showed that the bands related to PO43- were clearly higher in content for enamel than for dentine. Higher absorbance measured at the region of 2800-3700 cm-1 and at 1500-1800 cm-1 for dentine as compared to enamel samples were indicative of a higher content of organic structures. The highest contribution of phosphates was in canine enamel samples.The studies showed that the carbonate-to-phosphate ratio was higher for dentine (0.20 - 0.48) compared to the values obtained for enamel (0.13 - 0.22), however, minor differences were found in each group of enamel or dentine samples. The lack of significant differences between the enamel and dentine powders of incisors, canines, premolars and molars may prove that each extracted tooth, regardless of the tooth group, is an excellent substrate for their substitution.

Biomimetic Self-Maturation Mineralization System for Enamel Repair

Enamel repair is crucial for restoring tooth function and halting dental caries. However, contemporary research often overlooks the retention of organic residues within the repair layer, which hinders the growth of dense crystals and compromises the properties of the repaired enamel. During the maturation of natural enamel, the organic matrix undergoes enzymatic processing to facilitate further crystal growth, resulting in a highly mineralized tissue. Inspired by this process, a biomimetic self-maturation mineralization system is developed, comprising ribonucleic acid-stabilized amorphous calcium phosphate (RNA-ACP) and ribonuclease (RNase). The RNA-ACP induces initial mineralization in the form of epitaxial crystal growth, while the RNase present in saliva automatically triggers a biomimetic self-maturation process. The mechanistic study further indicates that RNA degradation prompts conformational rearrangement of the RNA-ACP, effectively excluding the organic matter introduced earlier. This exclusion process promotes lateral crystal growth, resulting in the generation of denser enamel-like apatite crystals that are devoid of organic residues. This strategy of eliminating organic residues from enamel crystals enhances the mechanical and physiochemical properties of the repaired enamel. The present study introduces a conceptual biomimetic mineralization strategy for effective enamel repair in clinical practice and offers potential insights into the mechanisms of biomineral formation.

The radiographic evaluation of 11 different resin composites

Radiopacities of dental materials used in restorations are very important in making the radiographic diagnosis. Therefore, the aim of our study was to evaluate the radiopacity of five single-shade and six simplishade resin composites with digital technique. Five different single-shade (Charisma Topaz One, Omnichroma, Clearfil Majesty ES-2 Universal, Vittra APS Unique, ZenChroma) and six different simplishade resin composites (G-aenial A'CHORD, Essentia Universal, OptiShade, Estelite Asteria, Filtek Universal, Filtek Z250) were used. For each group, five disk-shaped resin composites of 1 mm and 2 mm thicknesses were prepared. As a control, tooth slices with 1 mm and 2 mm thicknesses and a 99.5% pure aluminum step-wedge were used. The samples, tooth slices, and a step-wedge were placed on a photostimulable phosphor plate. Digital radiographs were taken from 30 and 40 cm distances (70 kVp, 7 mA 0.28 ms). The images were analyzed using ImageJ software to measure the mean gray values. Data were analyzed using SPSS 22 package program and Kruskal-Wallis H Test (p < 0.05). The highest radiopacity was seen in Filtek Universal at both distances and thicknesses. Omnichroma had the lowest radiopacity in all parameters. All specimens showed higher radiopacity than dentin. Except for Omnichroma 1 and 2 mm thick, Clearfil Majesty ES-2 Universal 2 mm thick, samples showed higher radiopacities than enamel (p < 0.05). The restorative materials tested were found to be more radiopaque than dentin. The samples passed the International Organization for Standardization for radiopacity values. The radiopacity values were affected by thickness and type of materials.

Natural, biphasic calcium phosphate from fish bones for enamel remineralization and dentin tubules occlusion

OBJECTIVES

A calcium phosphate extracted from fish bones (CaP-N) was evaluated for enamel remineralization and dentinal tubules occlusion.

METHODS

CaP-N was characterized by assessing morphology by SEM, crystallinity by PXRD, and composition by ICP-OES. CaP-N morphology, crystallinity, ion release, and pH changes over time in neutral and acidic solutions were studied. CaP-N was then tested to assess remineralization and dentinal tubules occlusion on demineralized human enamel and dentin specimens (n = 6). Synthetic calcium phosphate in form of stoichiometric hydroxyapatite nanoparticles (CaP-S) and tap water were positive and negative controls, respectively. After treatment (brush every 12 h for 5d and storage in Dulbecco's modified PBS), specimens' morphology and surface composition were assessed (by SEM-EDS), while the viscoelastic behavior was evaluated with microindentation and DMA.

RESULTS

CaP-N consisted of rounded microparticles (200 nm - 1 µm) composed of 33 wt% hydroxyapatite and 67 wt% β-tricalcium phosphate. In acidic solution, CaP-N released calcium and phosphate ions thanks to the preferential β-tricalcium phosphate phase dissolution. Enamel remineralization was induced by CaP-N comparably to CaP-S, while CaP-N exhibited a superior dentinal tubule occlusion than CaP-S, forming mineral plugs and depositing new nanoparticles onto demineralized collagen. This behavior was attributed to its bigger particle size and increased solubility. DMA depth profiling and SEM showed an excellent interaction between the newly formed mineralized structures and the pristine tissue, particularly at the exposed collagen fibrils.

SIGNIFICANCE

CaP-N demonstrated very good remineralizing and occlusive activity in vitro, comparable to CaP-S, thus could be a promising circular economy alternative therapeutic agent for dentistry.

Pulp chamber temperature changes and enamel surface analysis during orthodontic composite removal using 3 different burs in a repeatable approach: an experimental study

BACKGROUND

During the debonding phase every clinician has to take care of preserving the enamel structure and tooth temperature. The objective of this study was to analyze in vitro the increase of the pulp chamber temperature and the wearing of enamel surface, during adhesive removal after debonding.

METHODS

Sixty extracted human teeth were selected. An orthodontic bracket was bonded on each tooth and after bracket removal, intraoral scanner pictures were used to evaluate ARI for each tooth. Three different burs were tested: tungsten-carbide multiple blades, arkansas stone and ceramic bur. A mechanical arm controlled by a dedicated software was used to reproduce a repeatable act of composite removal. To analyze in vitro the pulp chamber temperature during the composite removal procedure, teeth were treated endodontically placing a thermocouple through the root canal from the apex. A software registered temperature changes in a continuous manner. The enamel surface of every tooth was tested after the removal of composite with an optical stereoscopic microscope.

RESULTS

An association existed between maximum internal pulp chamber temperature variation and irrigation (P<0.0001) and between maximum internal pulp chamber temperature variation and bur type (P=0.0133), with a significantly lower temperature increase produced by the arkansas bur. A significant difference among groups was detected for ESI and EDI assessment (P=0.002, P=0.010).

CONCLUSIONS

Considering the initial setup, temperature variation analysis showed more conservative results using the arkansas burs with irrigation. ESI and EDI indexes showed significant enamel surface damage using tungsten-carbide burs.

Changes in enamel hardness, wear resistance, surface texture, and surface crystal structure with glass ionomer cement containing BioUnion fillers

This study investigated the potential of BioUnion filler containing glass ionomer cement (GIC) to enhance the properties of enamel surrounding restorations, with a specific focus on the effect on hardness. The hardness of the bovine enamel immersed in the cement was measured using Vickers hardness numbers. Following sliding and impact wear simulations, the enamel facets were examined using confocal-laser-scanning microscopy and scanning-electron microscopy. Surface properties were further analyzed using energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD). A significant increase in Vickers hardness numbers was observed in the BioUnion filler GIC after 2 days. Furthermore, the mean depth of enamel facets treated with BioUnion filler GIC was significantly less than that of untreated facets. Characteristic XRD peaks indicating the presence of hydroxyapatite were also observed. Our findings imply that GIC with BioUnion fillers enhances the mechanical properties of the tooth surface adjacent to the cement.

Study on the effect of crystal changes on acid resistance of erbium laser etched enamel surface

To investigate the mechanism underlying high acid resistance of enamel after erbium laser etching. Forty-five premolars were collected and assigned to three groups. A 4×4×1 mm enamel sample was prepared, the left side was the control side, the right side was the treated side, which was treated with different surface treatments, including 35% phosphoric acid etching, Er:YAG laser etching, and Er,Cr:YSGG laser etching. The hydroxyapatite crystal size on the enamel surface of the samples was observed. The contents of Ca, P, O, F, Cl, C, Mg were detected. The crystallinity of the hydroxyapatite crystal was analyzed. After erbium laser etching, the enamel surface had high hydroxyapatite crystal size, beneficial content of chemical elements and crystallinity. The morphological and composition changes of crystals in the enamel surface after erbium laser etching may be one of the crucial mechanisms underlying the enhancement of acid resistance of enamel after erbium laser etching.

Aesthetic impact of resin infiltration and its mechanical effect on ceramic bonding for white spot lesions

BACKGROUND

Treating white spot lesions (WSLs) with resin infiltration alone may not be sufficient, raising questions about its compatibility with other treatments amid controversial or incomplete data. Therefore, this study aimed to assess the aesthetic feasibility of resin infiltration combined with bleaching, as well as its potential mechanical effect on ceramic bonding to WSLs.

METHODS

One hundred and fifty flat enamel surfaces of bovine incisors were prepared. Ninety specimens were deminerailized and randomly assigned to three groups(n = 30): post-bleaching resin infiltration (Bl-R), pre-bleaching resin infiltration (R-Bl), and only resin infiltration (R). Color, surface roughness and microhardness were assessed in immediate, thermocycling and pigmentation tests. The remaining sixty samples were randomly assigned to three groups (n = 20): control (Ctrl), bonding (Bo), pre-bonding resin infiltration (R-Bo). Shear bonding strength, failure mode, micro-leakage depth and interface morphology were evaluated after ceramic bonding. The Tukey test and analysis of variance (ANOVA) were used for statistical analysis.

RESULTS

For the effect of resin infiltration and bleaching on WSLs, the R-Bl group showed the worst chromic masking ability, with the highest |ΔL|, |Δa|, |Δb|, and ΔE values after treatment. Compared with those in the Bl-R group, the R-Bl and R groups showed significant time-dependent staining, which is possibly attributed to their surface roughness. For the effect of resin infiltration on the adhesive properties of WSLs, resin infiltration reduced the staining penetration depth of WSLs from 2393.54 ± 1118.86 μm to 188.46 ± 89.96 μm (P < 0.05) while reducing WSLs porosity in SEM observation.

CONCLUSIONS

Post-bleaching resin infiltration proved to be advantageous in the aesthetic treatment of WSLs. Resin infiltration did not compromise bonding strength but it did reduce microleakage and enhance marginal sealing. Overall, resin infiltration can effectively enhance the chromatic results of treated WSLs and prevent long-term bonding failure between ceramics and enamel. Based on these findings, the use of post-bleaching resin infiltration is recommended, and resin infiltration before ceramic bonding is deemed viable in clinical practice.

Evaluation of enamel surface integrity after orthodontic bracket debonding: comparison of three different system

OBJECTIVE

This study aimed to evaluate enamel surface integrity and time consumed during residual cement removal after bracket debonding using different adhesive removal burs with and without a dental loupe.

MATERIAL AND METHODS

Sixty human-extracted premolars were collected, cleaned, mounted, and prepared for orthodontic bracket bonding. Teeth were randomly divided into three main groups (n = 20) based on the adhesive removal method: tungsten carbide system (TC), sof-lex discs system (SD), and diamond system (DB) groups. Then, each group was subdivided into two subgroups (naked eye and magnifying loupe subgroups). The brackets were bonded and then debonded after 24 h, and the Adhesive Remnant Index (ARI) was assessed. The adhesive remnants were removed by different systems, and the final polishing was performed by Silicone OneGloss. The enamel surface roughness was evaluated before bracketing (T0), after residual cement removal (T1), and finally after polishing (T2) using surface Mitutoyo SJ-210 profilometry and Scanning Electron Microscopy (SEM) to determine the Enamel Damage Index (EDI) score. The time consumed for adhesive removal was recorded in seconds.

RESULTS

The Kruskal Wallis test showed a statistically significant difference in roughness values at T1 compared to T2 between subgroups (p < 0.001). When comparing EDI at T1 and T2, the Kruskal-Wallis H-test showed statistically significant differences in all subgroups. The pairwise comparisons revealed that EDI scores showed a statistically significant difference at T1 and T2 between DB vs. TC and SD (p = 0.015) but not between TC vs. SD (p = 1.000), indicating the highest roughness value observed in the DB group. The time for cement removal was significantly shorter in the magnifying loupe group than in the naked eye group and was shortest with the TC group, whereas the time was the longest with the DB group (p < 0.05).

CONCLUSION

All three systems were clinically satisfactory for residual orthodontic adhesive removal. However, TC system produced the lowest enamel roughness, while the DB system created the greatest. The polishing step created smoother surfaces regardless of the systems used for resin removal.

A Wnt10a-Notch signaling axis controls Hertwig's epithelial root sheath cell behaviors during root furcation patterning

Human with bi-allelic WNT10A mutations and epithelial Wnt10a knockout mice present enlarged pulp chamber and apical displacement of the root furcation of multi-rooted teeth, known as taurodontism; thus, indicating the critical role of Wnt10a in tooth root morphogenesis. However, the endogenous mechanism by which epithelial Wnt10a regulates Hertwig's epithelial root sheath (HERS) cellular behaviors and contributes to root furcation patterning remains unclear. In this study, we found that HERS in the presumptive root furcating region failed to elongate at an appropriate horizontal level in K14-Cre;Wnt10afl/fl mice from post-natal day 0.5 (PN0.5) to PN4.5. EdU assays and immunofluorescent staining of cyclin D1 revealed significantly decreased proliferation activity of inner enamel epithelial (IEE) cells of HERS in K14-Cre;Wnt10afl/fl mice at PN2.5 and PN3.5. Immunofluorescent staining of E-Cadherin and acetyl-α-Tubulin demonstrated that the IEE cells of HERS tended to divide perpendicularly to the horizontal plane, which impaired the horizontal extension of HERS in the presumptive root furcating region of K14-Cre;Wnt10afl/fl mice. RNA-seq and immunofluorescence showed that the expressions of Jag1 and Notch2 were downregulated in IEE cells of HERS in K14-Cre;Wnt10afl/fl mice. Furthermore, after activation of Notch signaling in K14-Cre;Wnt10afl/fl molars by Notch2 adenovirus and kidney capsule grafts, the root furcation defect was partially rescued. Taken together, our study demonstrates that an epithelial Wnt10a-Notch signaling axis is crucial for modulating HERS cell proper proliferation and horizontal-oriented division during tooth root furcation morphogenesis.

Prenatal exposure to environmental toxins and comprehensive dental findings in a population cohort of children

Environmental toxins are known to have many impacts on growth and development in humans, starting in utero. Alterations in amelogenesis, caused by chemical and physical trauma that occur during the antenatal, perinatal and postnatal time periods, may result in developmental defects in deciduous and permanent tooth enamel, as demonstrated in animal studies. These defects can be clinically visible and result in a variety of morphological and functional problems in the dentition. Since enamel does not remodel after formation, it may serve as a permanent record of insults during organ development.Our primary purpose was to investigate any possible relationship between intrauterine exposure to endocrine disrupting chemicals (phenols and phthalates) and developmental defects in enamel in children, while also accounting for fluoride exposure. Our secondary purpose was to report descriptively on findings from comprehensive dental examinations performed on 356 children that were drawn from the general paediatric population. A cohort of children from the Utah Children's Project (N = 356) that had full medical exams, comprehensive medical and family histories and available biospecimens were given extraoral and intraoral examinations. They also completed an oral health questionnaire. Standardized intraoral photographs were taken of the teeth and viewed by standardised examiners and the dental observations were recorded for a full inventory of findings, including: tooth morphology, caries, restorations, colorations, attrition, erosion, fractures and hypomineralization. Perinatal maternal urine samples were assessed for the concentration of fluoride, phenols and phthalates, including bisphenol A (BPA).Pairwise statistical analyses were done to correlate the dental findings with one another and with the presence of environment chemicals found in the urine samples. Hypomineralization was the most common finding (96% of children; 37% of deciduous teeth, 42% of permanent teeth), consistent with molar incisor hypomineralization (MIH) described in other human populations. No consistent correlations were seen between dental findings and the presence of phenols and phthalates in prenatal urine, but the number of samples available for the assessment was limited (n = 35).In conclusion, we found a high proportion of dental hypomineralization in a population based paediatric cohort, but did not find an association with prenatal exposure to phenols and phthalates.

New generation of orthodontic devices and materials with bioactive capacities to improve enamel demineralization

OBJECTIVE

The article reviewed novel orthodontic devices and materials with bioactive capacities in recent years and elaborated on their properties, aiming to provide guidance and reference for future scientific research and clinical applications.

DATA, SOURCES AND STUDY SELECTION

Researches on remineralization, protein repellent, antimicrobial activity and multifunctional novel bioactive orthodontic devices and materials were included. The search of articles was carried out in Web of Science, PubMed, Medline and Scopus.

CONCLUSIONS

The new generation of orthodontic devices and materials with bioactive capacities has broad application prospects. However, most of the current studies are limited to in vitro studies and cannot explore the true effects of various bioactive devices and materials applied in oral environments. More research, especially in vivo researches, is needed to assist in clinical application.

CLINICAL SIGNIFICANCE

Enamel demineralization (ED) is a common complication in orthodontic treatments. Prolonged ED can lead to dental caries, impacting both the aesthetics and health of teeth. It is of great significance to develop antibacterial orthodontic devices and materials that can inhibit bacterial accumulation and prevent ED. However, materials with only preventive effect may fall short of addressing actual needs. Hence, the development of novel bioactive orthodontic materials with remineralizing abilities is imperative. The article reviewed the recent advancements in bioactive orthodontic devices and materials, offering guidance and serving as a reference for future scientific research and clinical applications.

Epileptic encephalopathy and amelogenesis imperfecta: What about KohlschüttereTönz syndrome? Case report and literature review

BACKGROUND

KohlschüttereTönz syndrome (KTS), also called amelo-cerebro-hypohidrotic syndrome, is a very rare genetic condition, described for the first time by Kohlschutter, which typically manifests as a triad of symptoms:  amelogenesis imperfecta, infantile onset epilepsy, and intellectual disability. 47 cases were reported in English language literature since 1974-2021.

CASE REPORT

A 7-year-old girl was referred for dental evaluation. Oral examination revealed yellowish color of all the teeth due to enamel hypoplasia. The radiographic exam revealed a thin layer of enamel with decreased radiopacity of the enamel compared to that of dentin. The diagnosis of amelogenesis Imperfecta was established. In addition to that, the child's parents reported that she had spasticity, epileptic seizures and psychomotor developmental delay. The association of all these features leads us to conclude to KTS.

CONCLUSION

It seems that numerous cases of KTS are still undiagnosed in the world, so this paper highlights the common clinical features of Kohlschütter-Tönz Syndrome helping to an early diagnosis and more research about this condition.

Antagonist enamel tooth wear produced by different dental ceramic systems: A systematic review and network meta-analysis of controlled clinical trials

OBJECTIVES

The aim of this study was to evaluate the amount of enamel tooth wear induced by different antagonistic ceramic crown materials in the posterior area within a follow-up period up to 24 months in function. A network meta-analysis was performed to assess the effect of the materials on the mean vertical loss (MVL) of the antagonist enamel tooth surface.

DATA

Main search terms used in combination: ceramic, dental materials, metal ceramic, tooth wear and dental enamel.

SOURCES

An electronic search was conducted in PubMed/Medline, Embase, and Cochrane CENTRAL plus hand-searching.

STUDY SELECTION

Eligibility criteria included clinical studies reporting on MVL on antagonist's tooth up to 24 months following the permanent crown placement. From a total of 5697 articles, 7 studies reporting on 261 crowns for 177 subjects with 3 ceramic materials (Lithium disilicate, metal-ceramic, monolithic zirconia) were included. Among all, metal-ceramic and zirconia caused significantly higher enamel tooth wear on antagonist teeth, representing 82.5 µm [54.4; 110.6]) and 40.1 µm [22.2; 58.0]) more MVL than natural teeth group. In contrast, lithium disilicate showed only 5.0 µm [-48.2; 58.1]) more MVL than occurs on opposing natural teeth.

CONCLUSIONS

This systematic review demonstrated that prosthodontic ceramic materials produced significantly more antagonist enamel tooth wear than opposing natural enamel tooth wear, and ceramic material type was correlated to the degree of enamel tooth wear. Additional well-conducted, randomized controlled trials with homogeneous specimens are required due to inadequate sample size and number of the clinical studies included in the analyses.

CLINICAL SIGNIFICANCE

The amount of wear caused by different restorative materials has a high influence on the antagonistic natural teeth and should therefore be evaluated intensively by the dentist.

Why orthodontists need to know about molar incisor hypomineralization

Molar incisor hypomineralization (MIH) is a systemic developmental qualitative defect of the enamel that affects 1-4 first permanent molars with or without incisor involvement. Enamel hypomineralization is identified visually as a demarcated opacity with a clear border with varying extensions and can be white, yellow, or brown. This opacity is characterized by a reduced quality of enamel that is of normal thickness but not fully mineralized. It is very common for the affected teeth to present with posteruptive breakdown, making them susceptible to caries, leading to their subsequent loss. Thus, MIH is a significant dental problem with clinical, economic, and psychosocial implications. The planned extraction of compromised teeth is a valid alternative to complex restorative treatment. Orthodontists' involvement is essential in developing effective treatment strategies for children affected by MIH, contributing to their oral health and well-being.

White spot enamel lesions - is treatment or prevention the answer to this 'no win scenario'?

DESIGN

Prospective, randomized, double-blind, multicenter clinical trial.

CASE SELECTION

Participants between 12 and 25 years old, who were generally healthy, with 2 or more white spot lesions on the labial surface of anterior dentition.

DATA ANALYSIS

79 patients who developed white spot lesions (WSL) on the labial surface of anterior teeth following orthodontic treatment were randomly assigned to 4 intervention groups. Group 1 received 5% sodium fluoride varnish every 6 months, the second group received CPP-ACP every 6 months, the third group was treated with resin infiltration at the initial visit followed by placebo every 6 months, and the final group which was the control group was coated with 1400 ppm fluoride toothpaste every 6 months. All the candidates were instructed to brush twice daily using a specific toothbrush and 1400 ppm fluoride toothpaste. The study lasted for 12 months, and photographs of the teeth with WSL were taken before and after completion of the intervention. Photographs were analyzed using ImageJ software to compare the changes in the percentage of WSL area to total tooth surface area among the four study groups. The distribution differences among groups were compared using nonparametric tests and differences between baseline and 1-year follow-up parameters were analyzed using paired chi-square tests.

RESULTS

Reduction in the area of WSL were noted in all groups, with different levels of significance. The percentage reduction was 46.62% in the resin infiltration group and it was significantly higher than the remaining interventions. Fluoride varnish group had 26.57% reduction, the CPP-ACP group had 28.64% reduction and the control group had 29.75% reduction in the WSL area. Plaque index was noted to have significant correlation with the change in WSL area with higher plaque index scores demonstrating lesser reduction in WSL.

CONCLUSIONS

The study found that resin infiltration significantly reduced the WSL area after 1-year follow-up. Fluoride toothpaste with or without CPP-ACP and fluoride varnish produced some therapeutic effects.

Universal Adhesive Application Modes Differentially Affect the Fracture Resistance of Resin Composite Restored Teeth

This study evaluated the fracture resistance of teeth with mesio-occluso-distal (MOD) resin composite restorations using universal adhesive (Single Bond Universal; SBU) in three different manipulation modes compared with those using two-step self-etch (Clearfil SE bond; CSE) and 3-step etch-and-rinse (Scotchbond Multi-Purpose; SBMP) adhesives at 24 hours and after thermocycling. One hundred and sixty maxillary premolars were assigned into eight groups of 20 each. Intact teeth and nonrestored cavity-prepared teeth served as controls. For the remaining specimens, cavities were restored with resin composite using different adhesives-SBU in self-etch, etch-and-rinse, or selective enamel etching modes; CSE in self-etch or selective enamel etching; and SBMP. Specimens from each group were either stored in 37°C water for 24 hours or further submitted to thermocycling for 30,000 cycles (n=10), then subjected to axial compression stress until fracture. Fracture patterns were observed microscopically. Data were statistically analyzed at a 95% confidence level. Among the restored teeth, mean failure load of the group using SBMP was the highest at both short-term and long-term evaluation periods (p<0.05). Fracture strengths of the SBU groups where enamel was etched with phosphoric acid prior to the adhesive application were similar and were greater than in those specimens without pre-etching (p<0.05). After thermal aging, a significant decrease in fracture resistance value was detected only for the group using SBU in etch-and-rinse application mode (p<0.05). For the self-etch strategy, SBU demonstrated lower load to fracture than CSE following thermocycling; all specimens failed at and beneath the crestal level (p<0.05). Application of SBU universal adhesive in selective enamel etching mode provided higher and more stable fracture resistance of teeth with MOD resin composite restorations than in self-etch mode.

Influence of etchant type on the shear bond strength of orthodontic brackets to enamel

The aim of this study was to evaluate the influence of the type of etchant on the shear bond strength (SBS) of metallic brackets to enamel and the Adhesive Remnant Index (ARI) after debonding. A total of 30 mandibular and maxillary premolars were randomly distributed into groups (n = 10) treated with 1 of 3 enamel surface-conditioning agents: 35% phosphoric acid (PA), 35% glycolic acid (GA), or 35% ferulic acid (FA). The designated acid was applied to the buccal enamel surface of the tooth for 20 seconds, and the tooth was then rinsed with distilled water for 20 seconds and air dried for 5 seconds. A metal bracket was bonded to the prepared surface with light-cured orthodontic resin. After 24 hours, the bracket-tooth interface was submitted to SBS testing in a universal testing machine at a speed of 0.5 mm/min. After debonding, the enamel surface was observed under a stereomicroscope (×20 magnification) to determine the ARI. The generalized linear models showed that the PA and GA groups presented significantly higher SBSs than the FA group (P = 0.0003). The ARI was significantly higher in specimens treated with PA than with the other acids (P < 0.05; Kruskal-Wallis and Dunn tests), with a larger quantity of adhesive remaining adhered to the tooth. Both PA and GA are effective for bonding brackets, but GA resulted in a lower percentage of adhesive remnant adhered to the enamel.

The radiopacity of single-shade composite resins: A comparative evaluation

OBJECTIVE

The aim of this study was to evaluate the radiopacity of single-shade composite resins with group and multi-shade composite resins via a digital image analysis.

MATERIALS AND METHODS

Disc-shaped (5 mm in diameter, 2 mm in thickness) specimens were prepared with one multi-shade (Estelite Sigma Quick-ESQ), four single-shade (Omnichroma-OC, Charisma Topaz One-CTO, Vitra Unique-VU, and ZenChroma-ZC), three group-shade (G-aenial Achord-GA, Optishade-OS, and Estelite Asteria-EA), and one posterior composite resin (Estelite Posterior-EP) (n = 3). A radiographic image of all the specimens, an aluminum step-wedge, and a 2 mm thick tooth section were taken. Mean gray values (MGV) of the specimens, enamel, and dentin were calculated by ImageJ software. Composition analysis was performed with EDS, and SEM images (×10,000) were obtained. The data were analyzed with Kruskal-Wallis and Post hoc adjusted Bonferroni analysis (p = 0.05).

RESULTS

The mean MGV of CTO, the highest of all test groups, was significantly higher than OC and dentin (p = 0.04 and p = 0.009, relatively). The lowest mean MGV was also observed in a single-shade group, OC. EDS analysis showed that the tested materials comprised various radiopaque elements.

CONCLUSIONS

All of the single-shade and group-shade groups exceeded the MGV value of dentin, which is clinically expected from any restorative material.

CLINICAL SIGNIFICANCE

The radiopacity properties of various single-shade composite resins which as a category is a rising trend in esthetic dentistry were investigated. It is important for clinicians to be aware of novel materials' physical qualities including radiopacity, a daily clinical criteria for restorative materials.

Are S-PRG composites able to resist against erosive and abrasive challenges and protect surrounding enamel in situ?

OBJECTIVES

This study evaluated the resistance of S-PRG (Surface Pre-Reacted Glass-ionomer) composites and other restorative materials against erosive and abrasive challenges and their protective effect on enamel adjacent to the restorations.

MATERIALS AND METHODS

Bovine enamel blocks were prepared and randomized into 12 groups, including 6 types of material, each of them subjected to erosion_e or erosion+abrasion_ea: Beautifil II (S-PRG); Beautifil Bulk Restorative (S-PRG); Filtek Z250 XT; Filtek Bulk Fill; EQUIA Forte; Riva Light Cure. Cavities were prepared in the middle of enamel blocks and restored with the materials. Initial profiling measurement was performed on the material and on adjacent enamel (100, 200, 300, 600 and 700 μm from the restoration margin). Palatal intraoral appliances with the restored enamel blocks were used by the volunteers (n = 10). During 5 days appliances were immersed in 2.5 % citric acid for 2 min; 6 × /day (erosion_e). For ea condition, blocks were brushed for 1 min after each acid immersion. Final profile assessment was performed. Data were analysed by two and three way ANOVA followed by Tukey's test (p < 0.05).

RESULTS

Material wear: Riva Light Cure showed the highest wear followed by EQUIA Forte and then all resin composites, including the ones with S-PRG (p = 0.000). Enamel wear: there was significant interaction among type of restorative material, wear condition and distance (p = 0.014), enamel around materials showed similar wear (p = 0.983) and the enamel subjected to ea exhibited highest wear (p = 0.000).

CONCLUSION

SPRG based composites showed resistance against erosive and abrasive challenges but were not able to protect enamel adjacent to the restorations.

CLINICAL SIGNIFICANCE

S-PRG composites exhibit resistance to material wear comparable to resin composites. However, they have shown an inability to effectively protect the adjacent enamel under in situ erosive-abrasive conditions, despite the presence of mineral-loss-preventing ions surrounding materials.

The role of calcium in the prevention of erosive tooth wear: a systematic review and meta-analysis

OBJECTIVES

The loss of hard dental tissue due to recurrent acid challenges and mechanical stresses without bacterial involvement is known as erosive tooth wear (ETW). Many studies in the literature have concentrated on variables that may affect the ETW process and prevent its occurrence or reduce its advancement. However, to date, no previous systematic review has evaluated the role of calcium in preventing ETW. Therefore, the purpose of the present systematic review was to review and critically appraise the scientific evidence regarding the role of calcium formulations in the prevention of ETW.

METHODS

The review protocol was registered in the PROSPERO international prospective register of systematic reviews (Ref: CRD42021229819). A literature search was conducted in electronic databases to identify in situ randomized controlled trials evaluating the prevention of ETW following the application of calcium formulations. The outcomes studied included mean enamel loss, surface microhardness, surface roughness, mean erosion/softening depth, mineral loss/precipitation and remineralization. Study characteristics and outcomes of included studies were summarized. Cochrane's risk-of-bias tool 2.0 was used to assess the quality of eligible studies, and meta-analysis using a random effects model was performed.

RESULTS

The search retrieved 869 studies of which 21 were considered eligible. Regarding the results of the quality assessment for potential risk of bias in all included studies, overall, 5 studies were considered as being at low risk, another 12 at unclear risk and 4 at high risk of bias. The findings of the studies showed that the addition of calcium in juice drinks led to reduced enamel loss, with blackcurrant juice presenting 2.6 times statistically significant less enamel loss compared to orange juice (p = 0.0001, I2 = 89%). No statistically significant difference in mean surface microhardness of eroded enamel was recorded between chewing gum with or without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (p = 0.31, I2 = 71%). Contradictory were the results regarding the effect of milk and CPP-ACP pastes on prevention of ETW.

CONCLUSIONS

Calcium formulations play an important role in ETW prevention, mainly through their addition to acidic drinks.

Evaluation of the shear bond strength of various adhesives on the surface of enamel irradiated with various doses of radiotherapy

INTRODUCTION

We aimed to compare the shear bond strength (SBS) forces on the enamel surface with 2 adhesives after treatment with various radiation doses.

METHODS

A total of 120 premolars were included in the study. The teeth were randomly divided into 5 main groups (n = 24): negative control (without aging), positive control (with aging), 40 Gy, 60 Gy, and 70 Gy radiation. The 40 Gy, 60 Gy, and 70 Gy groups underwent conventional radiotherapy 5 days a week with a dose of 2 Gy each day. After the radiotherapy, all samples except the negative control group were subjected to thermal cycle aging. In all 5 groups, the specimens were divided into 2 subgroups, and half were bonded using 2 adhesives. After bonding, the universal Shimadzu test device was used to analyze the SBS. After the test, the tooth surfaces were examined under a stereomicroscope to determine the adhesive remnant index.

RESULTS

When adhesives were compared, Biofix adhesive's bond strength value was statistically higher in the 40 Gy group than in the Transbond XT group (P = 0.001). The SBS value was higher in all irradiated groups than in nonirradiated groups (P = 0.001). When the adhesive remnant index score was analyzed, no significant difference was found among the groups.

CONCLUSIONS

The SBS increased in irradiated teeth compared with unirradiated teeth, and the SBS values of both adhesives were within the acceptable limits in all radiation groups.

Analysis of Calcium and Phosphate Ion Extraction From Dental Enamel by Bleaching Gels Using Ion Chromatography, Micro-CT, and SEM

OBJECTIVES

To evaluate the volume and depth of enamel loss promoted by 37.5% and 7.5% hydrogen peroxide (HP) gels, and quantify the loss of calcium (Ca) and phosphate (P) ions by using ion chromatography (IC) analysis after bleaching.

METHODS

Sixty bovine enamel specimens were randomly divided into three groups: Control - no bleaching gel; HP37.5%, application of HP 37.5% for 45 minutes for 14 days; and HP7.5%, application of HP 7.5% for 3 applications of 8 minutes. The surface analysis (n=5) was performed using a scanning electron microscope (SEM) and dispersive energy system (EDS) to calcium and phosphorus dosage. The micro-CT was used for the enamel loss analysis (n=5). IC was used to analyze extracted Ca and P (n=10). Data were analyzed by one-way ANOVA and two-way repeated measures ANOVA, followed by Tukey and Dunnett's tests (α=0.05).

RESULTS

Significantly higher volume and depth of enamel loss were found for bleached groups compared with the control group. HP7.5% had significantly higher enamel change than HP37.5%. SEM showed higher enamel porosity for HP37.5% and HP7.5% compared to control. The IC demonstrated a significant increase of Ca incorporated into the gel, however, only HP7.5% had a higher P presence than the control group. The HP7.5% showed higher Ca and P ion exchange than HP37.5% (p<0.001).

CONCLUSION

HP37.5% and HP7.5%, caused enamel mineral changes compared with the control group. The IC method was demonstrated to be an effective methodology for detecting enamel mineral loss by the bleaching gel.

Evaluation of hydrogen peroxide permeability, color change, and physical-chemical properties on the in-office dental bleaching with different mixing tip

OBJECTIVE

This study aims to assess hydrogen peroxide (HP) penetration into the pulp chamber, color change (CC), physical-chemical properties, and material wastage (MW) and material used (MU) in mixing tips when using in-office bleaching gels with two different mixing tips.

MATERIALS AND METHODS

Forty teeth were divided into five groups (n = 8) based on the bleaching gels used (Pola Office +37.5% [PO+] and Whiteness HP Automixx Plus 35% [AM+]) and the mixing tip types (T-Mixer and Helical). A negative control group was treated with ultra-purified water. HP concentration was measured using UV-Vis, and CC was evaluated with a digital spectrophotometer. Initial concentration, pH, and viscosity were measured through Titration, a Digital pH meter, and Rheometer, respectively. MW and MU were measured using a precise analytical balance. Statistical analysis included two-way ANOVA, Tukey's, and Dunnett's test (α = 0.05).

RESULTS

A higher HP concentration was observed with PO+ with the Helical mixing tip in comparison with AM+ (p = 0.01). No significant differences in CC or MU were found for different mixing tips (p = 0.001). The T-mixer mixing tip resulted in significantly less MW (p < 0.00001) and improved mixture homogeneity and viscosity.

CONCLUSIONS

Utilizing a T-mixer with self-mixing bleaching gels achieves comparable CC while reducing MW. Moreover, it decreases HP penetration when using PO+.

CLINICAL SIGNIFICANCE

For the application of a self-mixing in-office bleaching gel, a T-mixer mixing tip should be recommended, as it reduces the penetration of hydrogen peroxide into the pulp chamber when using PO+, while also minimizing gel wastage.

An in vitro evaluation of the effects of fluoride, CPP-ACP, or resin infiltration on discoloration caused by pediatric supplements

OBJECTIVES

White spot lesions are more susceptible to staining agents due to their porous structure. This study examines the impact of white spot lesion treatments on discoloration caused by pediatric supplements.

METHOD AND MATERIALS

Three treatments (fluoride, casein phosphopeptide-amorphous calcium phosphate [CPP-ACP], resin infiltration), a control, and their respective syrup-based subgroups (iron and black elderberry syrups) were established, each with eight teeth. Artificial white spot lesions were induced, and weekly applications of fluoride varnish, daily applications of CPP-ACP paste, or a single resin infiltration procedure were performed on the white spot lesions within the treatment groups over 4 weeks. Simultaneously, samples were exposed daily to iron or black elderberry syrups. Spectrophotometer measurements were taken at baseline, after demineralization (T0), and after 1 (T1), 2 (T2), and 4 weeks (T4). ΔE00 values were calculated. Statistical analysis was conducted using a three-way mixed-design ANOVA, with the significance level set at P = .05.

RESULTS

At T4, ΔE00 values from all groups exceeded the clinical acceptability limit of 1.8. At T2 and T4, the ΔE00 values obtained from the black elderberry syrup subgroups were significantly higher (P < .001). At T4, the highest ΔE00 values were seen in the CPP-ACP groups (P < .001). The lowest ΔE00 values at T2 and T4 were observed in the resin infiltration groups (P < .05).

CONCLUSIONS

Supplements containing ferrous sulfate and black elderberry extract caused color changes in white spot lesions that exceeded the clinical acceptability limit. Resin infiltration of white spot lesions provides advantages over remineralization treatments, particularly in minimizing discoloration induced by pediatric supplements.

Effect of sonic oscillation on penetration and marginal adaptation of filled-resin-based fissure sealants

OBJECTIVES

To evaluate the effect of sonic oscillation on penetration depth and marginal adaptation of resin-based fissure sealants.

METHOD AND MATERIALS

Thirty-six extracted human third molars were randomized into three groups: in the HF group, teeth were sealed with a filled-resin-based sealant (Helioseal F); in the Sonic-HF group, teeth were sealed with Helioseal F and subjected to sonic oscillation (Compothixo Device, 140 Hz vibration frequency and ± 150 µm amplitude) before curing; in the CO group, teeth were sealed with an unfilled-resin-based sealant (Clinpro). All teeth were thermocycled for 1,500 cycles at 5°C and 55°C, then sectioned buccolingually into four sections (mesial, two middle, and distal). Sections were evaluated under SEM for marginal adaptation and scored. For penetration depth, three independent measurements from each tooth were recorded under SEM, and data were subjected to statistical analysis.

RESULTS

The group subjected to sonic oscillation (Sonic HF) resulted in significantly superior penetration depth and marginal adaptation compared with the HF group, but with no significant difference compared with the CO group.

CONCLUSIONS

Sonic activation of resin-based sealant increased penetration depth into fissures and marginal adaptation to the enamel wall without decreasing filler load or compromising sealant mechanical properties.

Effects of a Two-Step Silver Diamine Fluoride Varnish on Shear Bond Strength of Restorations, Dentin and Enamel Hardness, and Biofilm Formation

INTRODUCTION

Dental caries are a limiting factor in maintaining dental and medical readiness in the military. Untreated dental caries can lead to dire health consequences. Consistent and comprehensive access to dental care is often limited due to the intensive operational demands on our nation's warfighters. The standard of care for dental caries is a surgical model where diseased tooth tissue is surgically removed and restored with appropriate restorative materials. While effective, it is not practical in the military operational environment, especially under time constraints. Dental restoratives offer military personnel a simple and preventive treatment of dental caries and are suitable as self-applied first aids. The purpose of this study was to measure the shear bond strengths of two dental restorative materials to human teeth paired with two different fluoride treatments and the hardness and biofilm formation on teeth after applying the fluoride varnishes.

MATERIALS AND METHODS

Specimens were made of human molar teeth treated with each of the following four materials: glass ionomer cement GC Fuji II LC Capsules, Filtek Z250, Riva Star steps 1 and 2, or Mark3 NaF varnish. Step 1 of Riva Star consists of silver diamine fluoride and step 2 contains potassium iodide. On human molar slabs, 10 circular specimens of 5 cm in diameter were prepared with restoratives according to manufacturer procedures. Etch-Rite and a proprietary aluminum chloride-based cavity conditioner were used as etchants on tooth surfaces for the Filtek Z250 and glass ionomer cement, respectively. After at least 24 hours underwater, each assembly was removed, and the shear bond strength of the adhesive was measured according to International Organization for Standardization (ISO) 29022.The hardness was measured according to ISO 14233. Hardness measurements were performed before varnish application, then after storage in an incubator at 37 °C for 4 hours in a demineralization solution (pH = 4.5), and after 1 day in a mineralization solution (pH = 7). A crystal violet staining assay was used to measure biofilm formation of Streptococcus mutans bacteria on human molar teeth after the application of fluoride varnish.

RESULTS

We report a 16% increase in shear bond strength of the Filtek Z250/Riva Star coupled treatment compared to the Filtek Z250/Mark3 NaF coupled treatment. We also demonstrate a significant 84% decrease in bond strength with a GC Fuji II LC/Mark3 NaF treatment compared to control (P = .0002), while Riva Star remains statistically unchanged. Enamel and dentinal hardness are significantly improved when Riva Star is applied compared to NaF varnish. A 25%-35% (P < .0001) decrease in oral biofilm formation was observed on samples where a Riva Star or NaF varnish was applied.

CONCLUSIONS

Mechanical and antimicrobial testing indicated Riva Star, compared favorably with and in some cases, performed better in the laboratory than a Mark3 NaF varnish. Hardness measurements indicated Riva Star is more effective in dentin tubule occlusion compared to NaF varnish. Our findings help provide practical suggestions to dental treatment, particularly to the unique dental environments seen in the military. Riva Star may be used as an adjunctive treatment prior to placing a final restoration. This study supports the use of Riva Star in conjunction with GC Fuji II LC or Filtek Z250 restorative materials, making it a promising treatment in military dental applications.

Does surface enamel composition and characteristics vary with inter proximal enamel reduction?

OBJECTIVE

This study aimed to evaluate the chemical composition of the proximal enamel surface and the surface characteristics subjected to different extents of interproximal reduction (IPR) in a clinical setting.

MATERIALS AND METHODS

Premolars of orthodontic patients which were designated for extraction were subjected to .2 mm, .3 mm, and .5 mm of IPR. After 1 month, the teeth were extracted and the teeth were subjected to scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDX).

RESULTS

The SEM images of the three experimental groups (taken at magnification of 500 × and 2000 ×) showed that the enamel surfaces were irregular and rough compared to the honey comb appearance of the unstripped group. Small areas of erosion of enamel surface were seen in Group I (0.2 mm) under 2000 × magnification compared to Group IV (control) which showed typical arrangement of enamel rods in alternating orientation. The enamel surfaces of stripped and unstripped enamel contained calcium, phosphorus, carbon, oxygen, and nitrogen. The differences were not statistically significant and neither were the calcium phosphorous stoichiometric ratios between the four groups.

CONCLUSIONS

On analyzing the surface characteristics of enamel using SEM between the stripped and unstripped surfaces, there were irregularities and roughness seen in stripped surface whereas honey comb pattern was observed in unstripped enamel surfaces. The elements found in unstripped and stripped enamel surfaces were calcium, phosphorous, carbon, oxygen, and nitrogen. Although the calcium and phosphorus were high in the 0.5 mm IPR group, the difference between stripped and unstripped enamel surfaces was statistically not significant.

CLINICAL RELEVANCE

There have been concerns that IPR can remove the superficial mineral-rich layer making the deeper layers more susceptible to carious attack. No study has evaluated the mineral content in different layers of enamel in response to IPR in vivo and this study found no significant difference between pristine enamel and enamel subjected to IPR. The results of this study strengthen the validity of the clinical protocol employed.

Prevalence and clinical presentation of molar incisor hypomineralisation among a population of children in the community of Madrid

OBJECTIVE

The main objective of this study was to estimate the prevalence of molar incisor hypomineralisation (MIH), an alteration of tooth enamel with an estimated worldwide prevalence rate of 14%, among children using primary care services in the Community of Madrid, Spain.

MATERIALS AND METHODS

This was a descriptive, cross-sectional and multicentre study. After calibrating all researchers and following the diagnostic criteria of the European Academy of Paediatric Dentistry (EAPD), children aged between 8 and 16 years who were users of the dental services at 8 primary oral health units of the Madrid Health Service (SERMAS) were included. The children underwent a dental examination, and the parents were asked to complete a questionnaire.

RESULTS

The prevalence of MIH was 28.63% (CI: 24.61-32.65%). The age cohorts most affected by MIH were 8 years (21.4%) and 11 years (20.7%). The presence of MIH was greater among girls (85; 60.71%) than among boys (55; 39.28%). The mean number of affected teeth per patient was 4.46 ± 2.8. The most frequently affected molar was the upper right first molar (74.3%), and the upper left central incisor was the most affected incisor (37.85%). Opacities were the defects most frequently recorded (63.57%).

CONCLUSIONS

The prevalence of MIH in this study is the highest of all relevant studies conducted in Spain.

Molecular Evidence for Relaxed Selection on the Enamel Genes of Toothed Whales (Odontoceti) with Degenerative Enamel Phenotypes

Different species of toothed whales (Odontoceti) exhibit a variety of tooth forms and enamel types. Some odontocetes have highly prismatic enamel with Hunter-Schreger bands, whereas enamel is vestigial or entirely lacking in other species. Different tooth forms and enamel types are associated with alternate feeding strategies that range from biting and grasping prey with teeth in most oceanic and river dolphins to the suction feeding of softer prey items without the use of teeth in many beaked whales. At the molecular level, previous studies have documented inactivating mutations in the enamel-specific genes of some odontocete species that lack complex enamel. At a broader scale, however, it is unclear whether enamel complexity across the full diversity of extant Odontoceti correlates with the relative strength of purifying selection on enamel-specific genes. Here, we employ sequence alignments for seven enamel-specific genes (ACP4, AMBN, AMELX, AMTN, ENAM, KLK4, MMP20) in 62 odontocete species that are representative of all extant families. The sequences for 33 odontocete species were obtained from databases, and sequences for the remaining 29 species were newly generated for this study. We screened these alignments for inactivating mutations (e.g., frameshift indels) and provide a comprehensive catalog of these mutations in species with one or more inactivated enamel genes. Inactivating mutations are rare in Delphinidae (oceanic dolphins) and Platanistidae/Inioidea (river dolphins) that have higher enamel complexity scores. By contrast, mutations are much more numerous in clades such as Monodontidae (narwhal, beluga), Ziphiidae (beaked whales), Physeteroidea (sperm whales), and Phocoenidae (porpoises) that are characterized by simpler enamel or even enamelless teeth. Further, several higher-level taxa (e.g., Hyperoodon, Kogiidae, Monodontidae) possess shared inactivating mutations in one or more enamel genes, which suggests loss of function of these genes in the common ancestor of each clade. We also performed selection (dN/dS) analyses on a concatenation of these genes and used linear regression and Spearman's rank-order correlation to test for correlations between enamel complexity and two different measures of selection intensity (# of inactivating mutations per million years, dN/dS values). Selection analyses revealed that relaxed purifying selection is especially prominent in physeteroids, monodontids, and phocoenids. Linear regressions and correlation analyses revealed a strong negative correlation between selective pressure (dN/dS values) and enamel complexity. Stronger purifying selection (low dN/dS) is found on branches with more complex enamel and weaker purifying selection (higher dN/dS) occurs on branches with less complex enamel or enamelless teeth. As odontocetes diversified into a variety of feeding modes, in particular, the suction capture of prey, a reduced reliance on the dentition for prey capture resulted in the relaxed selection of genes that are critical to enamel development.

Possible uses of Hunter-Schreger bands of dental enamel for automated personal identification

BACKGROUND

Hunter-Schreger bands (HSB) are optical phenomena observed on tooth surfaces under polarized light, resulting from the intersection of enamel prisms. Anthropological studies demonstrate the prevalence of HSB in large mammals, contributing to enamel resistance. Historically, John Hunter and Schreger depicted HSB in dental literature. In dentistry, HSB play a role in non-carious cervical lesions (NCCL) and internal dental perikymata, suggesting their potential for personal identification. Personal identification, crucial in both daily and professional life, involves biometric characteristics, such as fingerprints or facial recognition. The need for non-invasive, rapid, and user-friendly methods has prompted the exploration of using HSB dental images for personal identification. The review aimed to consolidate studies employing HSB for personal identification.

METHODS

The scoping review was carried out strictly following the PRISMA-ScR checklist; the search was carried out on tree databases (PubMed, Scopus, Science Direct,) and a register (Cochrane library).

RESULTS

The research produced a number of bibliographic sources totaling 410. With the removal of duplicates, 334 were obtained; potentially eligible articles amounted to 14, of which only 4 fully complied with the criteria of eligibility.

CONCLUSIONS

From the data in the literature, we can assert that HSB could be used in personal identification, as they are characteristics that are difficult to change and easily detectable.

Investigating the efficacy of a varnish containing gallic acid on remineralization of enamel lesions: an in vitro study

This study evaluated the efficacy of a formulated remineralizing gallic acid (GA) varnish in treating artificial enamel caries lesions. Fifty-five intact bovine incisors were collected. Enamel blocks (5 × 9 mm) were prepared. A third of each block's surface remained intact. Primary carious lesions were induced on the middle and bottom thirds of the blocks by immersing the samples in a demineralization solution for 6 h. The bottom third of the blocks were further remineralized by randomly applying 0.5%, 2%, or 8% GA varnishes and 2.26% fluoride varnish (V varnish, Vericom, Seoul, Korea), or the varnish base without active ingredients (n = 11 each). The specimens were immersed in a remineralizing solution for 4 h and then subjected to a 2-hour immersion in the demineralizing solution. After six days of pH cycling, the surface microhardness was measured at depths of 30, 75, and 120 μm. The percentage of surface microhardness recovery (SMHR%) was compared among the groups using the Shapiro-Wilk, ANOVA, and Tukey HSD post-hoc tests (α = 0.05). The SMHR% of all experimental groups was higher than the control group at 30 μm (p < 0.05). The 0.5% GA varnish showed the highest SMHR% at all depths; however, the difference with the other experimental groups was significant at a depth of 30 μm (p < 0.05). The SMHR% of the fluoride and the 2% and 8% GA varnishes was comparable at all depths. All treatments potentially remineralize enamel lesions, with 0.5% GA varnish having the greatest effect, particularly on the top surface layer. As such, this newly developed varnish may emerge as a promising alternative to fluoride varnish.

Effects of enamel moistening and repositioning guide color on tooth whitening outcomes: A clinical trial

This clinical trial investigated the effects of pre-application enamel moistening on the impact of a 37% carbamide peroxide whitener on tooth color changes and the influence of repositioning guide colors. Forty participants were randomly assigned to in-office tooth bleaching with either moistened enamel (experimental) or dry enamel (control). The whitener was applied for 45 min over two sessions. Tooth color was visually measured or assessed using a spectrophotometer with purple or green silicone guides. Tooth bleaching was assessed using CIE76 (ΔEab ) and CIEDE2000 (ΔE00 ) formulas and by whitening and bleaching index score changes. Moistening the enamel did not significantly affect tooth color. However, the guide color choice only impacted tooth color when measured instrumentally. At baseline, the green guide resulted in statistically significantly whiter teeth than the purple guide. Less pronounced differences in the b* coordinate between baseline and final measurements were found using the green guide. The green guide also produced lower ΔEab values and less change in indexes. In conclusion, moistening the enamel did not significantly impact tooth color changes. However, the repositioning guide color influenced the tooth bleaching measured instrumentally, except for ΔE00 .

Evaluating color stability and enamel surface roughness following resin infiltration treatment

OBJECTIVE

To assess the impact of resin infiltration treatment on enamel color stability and surface roughness after simulating daily exposure to coffee stains and regular toothbrushing with standard toothpaste.

MATERIALS AND METHODS

In this in vitro study, we utilized 47 caries-free human enamel specimens, which were divided into two distinct groups. The teeth in the study group underwent artificial demineralization, Icon resin infiltration, and polishing, while the control group received only polishing. Following this, all teeth from both groups were regularly immersed in freshly brewed coffee for 15 min, twice daily, over a span of 30 days. After each staining session, the teeth underwent 10 heavy circular strokes using a soft toothbrush and standard toothpaste. Color changes were measured on Days 1 and 30 using a spectrophotometer. The L*, a*, b* color system defined by the International Commission on Illumination was used to assess the changes. Surface roughness was evaluated at baseline and after 30 days using a 3D surface Metrology Microscope.

RESULTS

After 30 days of immersion in coffee, both the study and control groups showed significant changes in color. However, differences were statistically significant between groups for "L" and "a" parameter but not for "b." The overall color change in the study group was higher than the control group. There were no significant differences in surface roughness within or between the groups before and after staining and brushing.

CONCLUSIONS

Resin infiltration leads to a significant increase in staining compared to untreated enamel. These staining properties should be taken into account when making clinical decisions regarding the treatment of white spot lesions.

Effects of repeated etching cycles using 15% hydrochloric acid on enamel loss and relative attenuation coefficient in resin infiltration

BACKGROUND

Resin infiltration is used to mask enamel opacities and the recommended etching cycles are three. However, anecdotal evidence suggests that favorable esthetics outcomes can be obtained by increasing the etching cycles.

AIM

To determine the incremental and total enamel loss when enamel surfaces are exposed to multiple etching cycles and to assess the relative attenuation coefficient after multiple etching cycles and resin infiltration treatment.

METHODS

Ninety extracted sound human premolars teeth were divided into 9 groups (n = 10); with each consecutive group having one additional etching cycle up to 9 cycles. The teeth were scanned with optical coherence tomography and enamel loss and attenuation coefficient were measured with MATLAB software. Enamel loss (one-way ANOVA, p ≤ 0.05) and attenuation coefficient (two-way ANOVA, p ≤ 0.05) were statistically analyzed.

RESULTS

There was a significant total enamel loss of more than 33% found at the 7th etching cycle and more. There was no statistically significant difference in the incremental mean depth of penetration of resin between various etching cycles (F(8, 134) = [2.016], one-way ANOVA, p = 0.185).

CONCLUSION

This study recommends that etching should not be repeated more than seven cycles to prevent excessive enamel loss. Following eight etching cycles, resin infiltration penetration appears approximately equal to that of healthy enamel.

A new role for resveratrol: Protection of enamel against erosion

OBJECTIVE

The aim of this study was to determine the effect of different concentrations of resveratrol in protecting enamel against initial dental erosion in vitro.

METHODS

Ninety bovine enamel samples (4 × 4 mm) were divided into six groups: Phosphate buffered saline (negative control; PBS), Commercial solution (Elmex Erosion Protection™; positive control) and resveratrol at 4 different concentrations (1, 10, 100 or 400 µg/mL). Initially, the samples were incubated in saliva for the formation of the acquired pellicle (250 µL, 1 h, 37 °C, 250 rpm). Afterward, the samples were incubated in the respective treatments (250 µL, 1 min, 37 °C, 250 rpm) and then reincubated in saliva (250 µL, 1 h, 37 °C, 250 rpm). Finally, the samples were subjected to an erosive challenge by incubating in 1 % citric acid (1 mL, pH 3.5, 1 min, 25 °C, 250 rpm). The percentage surface microhardness change (% SMC) was assessed using a microhardness tester. Data were analyzed by Kruskal-Wallis and Dunn's tests (p < 0.05).

RESULTS

The treatments with Elmex™ and resveratrol (1, 10 and 100 µg/mL) significantly protected enamel compared to the negative control, without significant differences among them. However, the group treated with the highest resveratrol concentration (400 µg/mL) did not show a significant difference from the negative control.

CONCLUSIONS

Resveratrol at concentrations ranging from 1 to 100 µg/ml was effective in preventing loss of enamel surface microhardness.

CLINICAL SIGNIFICANCE

This result suggests a potential new direction for the development of dental products based on resveratrol for the prevention of dental erosion.