The Effect of Food Polymers (Pectin, Alginate, and Gum Arabic) on Carbonated Drink-Induced Enamel Demineralization: An In Vitro Study

INTRODUCTION

The increased use of soft drinks leads to a high prevalence of dental erosion (DE), and the use of polymers can decrease tooth demineralization by a carbonated drink. Assessment of the effect of food-approved polymers such as highly esterified pectin (HP), propylene glycol alginate (PGA), and gum arabic (GA) on their efficiency to reduce enamel demineralization on addition with a commercially available carbonated drink was the main objective of this study.

MATERIALS AND METHODS

For this study, 300 premolar teeth were studied for enamel erosion and were divided into five groups consisting of 60 samples in each group. The teeth treated with distilled water had negative control, a commercially available carbonated drink with pH 2.7 had positive control, and food polymers were added individually to the carbonated drink in a specified quantity with minimal pH change and were taken as groups A, B, and C, respectively. The enamel erosion that occurred in study groups was measured using a laser fluorescence spectroscopic system with laser excitation at 404 nm at different treatment times (30, 60, and 120 seconds).  Results: Demineralization was less in samples treated with polymer added to carbonated drink solutions compared to samples exposed to plain carbonated drink. As the time of exposure increased up to 120 seconds, a significant decrease in demineralization occurred in polymer-treated groups of samples as against plain carbonated drink with HP showing more decreased demineralization with extended exposure periods compared to other polymers. The surface morphology of tooth samples exhibited the anti-erosive effect of polymers, and the scanning electron microscopic pictures revealed a smoother surface for the polymer-added group.

CONCLUSION

This study shows the efficacy of HP, PGA, and GA on reducing the effect of carbonated drink-induced enamel demineralization, and these polymers' addition to drinks can be an innovative way to reduce the demineralization potential of carbonated acidic drinks.

Effect of Fluoride Release on Enamel Demineralization Adjacent to Orthodontic Brackets

INTRODUCTION AND AIM

This study aimed to evaluate the ability of fluoride-releasing adhesives to inhibit enamel demineralization surrounding orthodontic brackets.

METHODS

Two groups of 40 sound human premolars were sectioned mesio-distally. The halves were varnished, and orthodontic brackets were bonded with different adhesive materials. An area 1 mm wide surrounding the brackets was left exposed. Each specimen was immersed daily in a pH cycle for 28 days. In the second group, the specimens were exposed daily to a fluoride solution (250 ppm F-) at 37°C. The fluoride release from different groups was measured. Quantitative light-induced fluorescence (QLF) was used to quantify fluorescence loss of enamel surfaces adjacent to the brackets. Results were statistically analyzed using ANOVA at (p<0.05).

RESULTS

Fluoride released from the three fluoride-releasing adhesives was significantly higher (p<0.001) in the group with daily fluoride exposures than in the group without fluoride exposures. Enamel adjacent to brackets bonded with Fuji Ortho LC, Ketac Cem, and Dyract Cem showed significantly less (p<0.001) changes in (ΔQ) value (less demineralization) than enamel bonded with Transbond, the control adhesive material.

CONCLUSIONS

Using fluoride-releasing adhesives significantly reduced the level of demineralization adjacent to orthodontic brackets.

Integrated Multiplex Sensing Clear Aligner for In Situ Monitoring of Dental Enamel Demineralization

Clear aligners have become one of the most important tools in orthodontic treatment. However, over a lengthy period of orthodontic treatment, enamel demineralization or even dental caries could be susceptible for occurrence. Therefore, early diagnosis of enamel demineralization has been widely investigated. Nevertheless, for reasons including bulky monitoring equipment and complexity of operation, few techniques reported to date possessed clinical utility. The combination of flexible electronics and electrochemical sensing technology presented a promising strategy. Herein, an integrated multiplex sensing clear aligner (IMSCA) system, including a clear aligner with a multiplex sensor array patch, was developed for in situ monitoring of Ca²⁺, pH, and PO₄^3- in the oral environment to provide a foundation for early diagnosis of enamel demineralization. The IMSCA exhibited a broad linear response range, great selectivity, temporal stability, reproducibility, and biological safety. Results of enamel demineralization simulating experiments and human permanent tooth demineralization experiments validate the capability of the IMSCA to indicate the occurrence of enamel demineralization. All results ultimately point to the promising clinical utility of the IMSCA, which facilitates the quantitative characterization of enamel demineralization in complex oral environments. This study provides a novel strategy in the early diagnosis of enamel demineralization.

Long-Term Chromatic Durability of White Spot Lesions through Employment of Infiltration Resin Treatment

Background and Objectives: White spot lesions (WSLs) denote regions of subsurface demineralization on the enamel that manifest as opaque and milky-white regions. Treatment for WSLs is essential for both clinical and aesthetic reasons. Resin infiltration has been identified as the most efficacious solution for alleviating WSLs, but studies with long-term monitoring are scarce. The aim of this clinical study is to assess the color change stability of the lesion after four years of implementing the resin infiltration technique. Materials and Methods: Forty non-cavity and unrestored white spot lesions (WSLs) were treated with the resin infiltration technique. The color of the WSLs and adjacent healthy enamel (SAE) was assessed using a spectrophotometer at T0 (baseline), T1 (after treatment), T2 (1 year after) and T3 (4 years after). The Wilcoxon test was utilized to determine the significance of the variation of color (ΔE) between WSLs and SAE over the observed time periods. Results: When comparing the color difference ΔE (WSLs-SAE) at T0-T1, the Wilcoxon test demonstarated a statistically significant difference (p < 0.05). For ΔE (WSLs-SAE) at T1-T2 and T1-T3, the color variation was not statistically significant (p = 0.305 and p = 0.337). Conclusions: The study's findings indicate that the resin infiltration technique is an effective solution for resolving the appearance of WSLs, and the results have demonstrated stability for a minimum of four years.

White Spot Lesions (WSLs)-Post-Orthodontic Occurrence, Management and Treatment Alternatives: A Narrative Review

Although treatment with fixed or mobile appliances has become an important part of modern orthodontics, side effects such as white spot lesions (WSLs) have a negative impact on the aesthetic outcome of orthodontic treatment. The purpose of this article was to review current evidence on the diagnosis, risk assessment, prevention, management and post-orthodontic treatment of these lesions. Data collection was performed electronically, and the initial search using the keywords "white spot lesions", "orthodontics", "WSL", "enamel" and "demineralization" in different combinations resulted in 1032 articles for the two electronic databases used. Ultimately, a total of 47 manuscripts were considered relevant to the aim of this research and included in this review. The results of the review indicate that WSLs remain a significant problem during orthodontic treatment. According to studies in the literature, the severity of WSLs correlates to the duration of treatment. Using toothpaste with more than 1000 ppm fluoride at home reduces the frequency of WSL separation and regular application of varnishes in the office reduces the frequency of the occurrence of WSLs only in the context of maintaining a strict hygiene regime. The old hypothesis that elastomeric ligatures retain more dental plaque than metal ones has been refuted. There are no differences in the appearance of WSLs between conventional brackets and self-ligating brackets. Clear aligner mobile devices develop fewer WSLs but are more extensive as opposed to conventional fixed devices, while lingual orthodontic appliances have a lower incidence of WSLs, and the most effective device for preventing these lesions is WIN, followed by Incognito.

Morphological Characteristics and Prevention of Tooth Enamel Demineralization during Orthodontic Treatment with Non-Removable Appliances

Despite the large number of studies on the effect of braces on teeth, there is no information on the dynamics of the state of the ultrastructure of the hard tissues of teeth during orthodontic treatment. The purpose of this study is to examine the state of the hard tissues of the teeth and carry out preventive measures to reduce the risk of complications in the process of orthodontic treatment using a non-removable device. Methods: For the in vitro study, 68 teeth were randomly divided into group A-no prophylactic treatment, and group B-treated with the fluorine varnish Tiefenfluorid. After 35 days, all the teeth were prepared for microscopic examination. The clinical study included 59 patients aged 12-17 years with orthodontic brackets. The split-mouth technique was used. The areas around the bracket of one-half of the oral cavity were treated with Tiefenfluorid every 6 months during the entire treatment period. The teeth of the second half of the oral cavity served as the control group. The data were processed in the SPSS19 package. Results: In vitro and clinical study results showed a statistically significant difference between the prophylactic and control groups of teeth in favor of the prophylactic group, where the statistical significance was p ≤ 0.01.

A novel dental infiltration resin based on isosorbide-derived dimethacrylate with high biocompatibility, hydrolysis resistance, and antibacterial effect

Objectives: The available infiltration resin has raised biosafety and treatment stability concerns because of the cytotoxicity of the main component, TEGDMA, and its susceptibility to hydrolysis in the oral environment. This study aimed to develop a TEGDMA-free infiltration resin to overcome these drawbacks. Methods: Using the synthetic bioderived monomer bis(methacrylate) isosorbide (IBM) and the zwitterionic compound 2-methacryloyloxyethyl phosphorylcholine (MPC), a novel infiltrant IBMA was developed and preferentially selected. We investigated the performance of the IBMA resin regarding cytotoxicity, antibiofilm adhesion, and hydrolysis resistance and further verified its ability to restore the demineralized enamel and stability of the infiltrated area under artificial aging conditions. Results: Compared with the commercial TEGDMA-based infiltration resin ICON, IBMA not only demonstrated similar enamel morphologic and esthetic restorative effects in chalky lesions but also exhibited favorable cell viability, durable Streptococcus mutans UA159 biofilm-repellent performance, and higher enamel microhardness (204.0 ± 5.12 HV) of the infiltrated enamel. Specifically, because of the high crosslink density [(47.77 ± 5.76) ×103 mol/mm3] and low water sorption [12.79 ± 2.56 µg/mm3] of the polymer network, the IBMA resin was more resistant to hydrolysis than ICON, which prevents the disruption of the infiltrant's micropore-blocking effect after aging. Enamel lesions treated with IBMA demonstrated good color stability after the tea-staining challenge, which was significantly better than that in the ICON group. Conclusion: Based on these findings, the IBMA resin exhibits favorable cell viability, hydrolysis resistance, and biofilm-repellent properties, which alleviates the defects of traditional TEGDMA systems. Therefore, it is a better alternative for microinvasive treatment involving early caries and enamel whitish discoloration.

Salivary retention of silver diamine fluoride

The topically applied fluorides are efficacious in both prevention against caries attack and inhibition of virulent bacteria. The purpose of this clinical trial was to assess the fluoride concentration in saliva before and after 38% SDF, 5% NaF and 1.23% ApF gel application on enamel and duration of its availability at different time intervals. The present randomized clinical trial was conducted among 60 healthy children aged between 6-12 years where at baseline the participants were instructed to spit for 2 min in sterile containers and the first saliva sample (S1) was taken. The participants were then randomly allocated into 3 different groups in which 38% Silver diamine fluoride, 5% Sodium fluoride and 1.23% ApF gel were applied respectively. The second saliva sample (S2) was collected after 5 min and patients were called after 1 hour for third saliva sample collection. The fluoride concentration was measured in the salivary samples. ANOVA test was used for evaluation and chi square t test was conducted for comparison of 3 groups. The fluoride concentration is comparatively slightly higher for the group receiving SDF than NaF and ApF at baseline, 5 min and 1 hour time interval but is not statistically significant. The mean scores of Fluoride concentration of the three groups were statistically significant at 5 min (F=63.556, p<0.0005) and 1 hour time interval (F=17.577, p<0.0005). Slightly increased salivary fluoride retention was observed post SDF application at 5min and 1 hour time interval when compared to Na F and ApF gel application. The present trial also concluded that topical fluoride application increases fluoride bioavailability in saliva thereby increasing tooth remineralization.

[Modern instrumental methods for early diagnosis of dental caries]

An overview of the existing devices on the world market for detecting foci of demineralization and hidden carious cavities is presented, their capabilities and principle of operation are analyzed. Dental morbidity among the children's population in our country remains high, which is largely due to insufficient attention to the identification and registration of initial foci of enamel demineralization. The study made it possible to evaluate the effectiveness of existing hardware methods for early diagnosis of caries in children and adults.

Analysis of enamel/restoration interface submitted cariogenic challenge and fluoride release

The treatment of high-risk patients still is a challenge. The understanding and development non-invasive, non-destructive, and non-ionizing techniques, can help to guide the treatment and the diagnosis of primary and recurrent caries. The present study evaluated the behavior of enamel/restoration interface after a cariogenic challenge by Fourier domain optical coherence tomography (FD-OCT), scanning electron microscopy (SEM) examination, and the fluoride release of the different restorative materials. Cavities (1.5 × 0.5 mm) were performed in enamel surface and divided into groups (n = 8): glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), and resin composite (RC). The samples were submitted to pH-cycling, and the solutions analyzed for cumulative fluoride by ion-analyzer. The morphology was analyzed by SEM through replicas. The optical attenuation coefficient (OAC) was calculated through exponential decay from the images generated by FD-OCT. Data were analyzed considering α = 0.05. OAC values increased for all groups after pH-cycling indicating demineralization (p < .05). Considering the remineralizing solution, RMGIC presented higher fluoride release rate, followed by GIC, while RC did not release any fluoride. Yet for the demineralizing solution, RMGIC and GIC released similar fluoride rates, overcoming RC (p < .05). Micrographs revealed no changes on the restorations margins, although enamel detachment was observed for RC and GIC after pH-cycling.

Synergism of Streptococcus mutans and Candida albicans Reinforces Biofilm Maturation and Acidogenicity in Saliva: An In Vitro Study

Early childhood caries, a virulent-form of dental caries, is painful, difficult, and costly to treat that has been associated with high levels of Streptococcus mutans (Sm) and Candida albicans (Ca) in plaque-biofilms on teeth. These microorganisms appear to develop a symbiotic cross-kingdom interaction that amplifies the virulence of plaque-biofilms. Although biofilm studies reveal synergistic bacterial-fungal association, how these organisms modulate cross-kingdom biofilm formation and enhance its virulence in the presence of saliva remain largely unknown. Here, we compared the properties of Sm and Sm-Ca biofilms cultured in saliva by examining the biofilm structural organization and capability to sustain an acidic pH environment conducive to enamel demineralization. Intriguingly, Sm-Ca biofilm is rapidly matured and maintained acidic pH-values (~4.3), while Sm biofilm development was retarded and failed to create an acidic environment when cultured in saliva. In turn, the human enamel slab surface was severely demineralized by Sm-Ca biofilms, while there was minimal damage to the enamel surface by Sm biofilm. Interestingly, Sm-Ca biofilms exhibited an acidic environment regardless of their hyphal formation ability. Our data reveal the critical role of symbiotic interaction between S. mutans and C. albicans in human saliva in the context of pathogenesis of dental caries, which may explain how the cross-kingdom interaction contributes to enhanced virulence of plaque-biofilm in the oral cavity.

[Effect of orthodontic traction on the microstructure of dental enamel]

OBJECTIVE

To investigate the effect of orthodontic traction on the microstructure of dental enamel.

METHODS

Forty-eight isolated premolars were randomly divided into 6 groups (n=8), including Group A (blank control group), in which the teeth were bonded with the orthodontic brackets without any loading force; Groups B1, B2, and B3 where the teeth were bonded with the orthodontic brackets using clinical adhesives and loaded with 50 g force for 6 months, 200 g force for 6 months, and 200 g force for 1 month, respectively; and Groups C1 and C2, where the teeth were bonded with straight wire brackets using light curing bonding and chemical curing bonding techniques, respectively. All the teeth were embedded with non-decalcified epoxy resin. Scanning electron microscope (SEM), atomic force microscope (AFM), and energy spectrometer (EDS) were used to analyze interface morphology and elemental composition of the teeth sliced with a hard tissue microtome.

RESULTS

Compared with those in Group A, the teeth in the other 5 groups showed increased adhesive residue index with microcracks and void structures on the enamel surface under SEM; AFM revealed microcracks on the enamel surface with angles to the grinding direction. A larger loading force on the bracket resulted in more microcracks on the enamel interface. The interface roughness differed significantly between Groups A and C2, and the peak-to-valley distance differed significantly between Groups A, C, and C2.

CONCLUSIONS

Orthodontic traction can cause changes in the microstructure of normal dental enamel.

Protective Effects of GIC and S-PRG Filler Restoratives on Demineralization of Bovine Enamel in Lactic Acid Solution

This study was aimed at investigating the protective effects of glass ionomer cement (GIC) and surface pre-reacted glass ionomer (S-PRG) fillers used as dental restorative materials on demineralization of bovine enamel. GlasIonomer FX ULTRA (FXU), Fuji IX GP Extra (FIXE), CAREDYNE RESTORE (CDR) were used as GICs. PRG Barrier Coat (BC) was used as the S-PRG filler. They were incubated in a lactic acid solution (pH = 4.0) for six days at a temperature of 37 °C. The mineral was etched from the enamel surface, and a large number of Ca and P ions were detected in solution. The Al, F, Na, Sr, and Sr ions were released in GICs and S-RPG fillers. The Zn ion was released only in CDR and the B ion was released only in BC. The presence of apparent enamel prism peripheries was observed after six days of treatment for the group containing only enamel blocks. pH values for the FXU, FIXE, CDR, BC, and enamel block groups after six days were 6.5, 6.6, 6.7, 5.9, and 5.1, respectively. Therefore, the observed pH neutralization effect suppressed progression of caries due to the release of several ions from the restoratives.

Spectrophotometric Evaluation of Enamel Color Variation Using Infiltration Resin Treatment of White Spot Lesions at One Year Follow-Up

The aim of this study is to evaluate the color changes and the stability at a 1-year follow-up of white spot lesions (WSLs) treated with an infiltrating technique by using etching and TEGDMA resin. The color of 22 white spot lesions and the sound adjacent enamel (SAE) were assessed with a spectrophotometer at T0 (baseline), T1 (after treatment), and T2 (1 year after). The color change ΔE (WSLs-SAE) at T0 vs. T1 were compared to evaluate the camouflage effect efficiency, and at T1 vs. T2 to assess the stability of outcomes. To evaluate the effect on the treatment outcome of gender, the presence or not of previous orthodontic treatment, WSLs onset more/less than 10 years, the age of the patient, and the ΔE WSL (T0 vs. T1) was analyzed. The difference between ΔE (WSLs-SAE) at T0 and T1 resulted in statistical significance (p < 0.01). No statistical difference was found between ΔE (WSLs-SAE) at T1 vs. T2. The variables considered showed no statistical differences in treatment outcomes. The results of our investigation show that the technique used is immediately effective and the camouflage effect keeps up and steady one year after treatment. Such results do not appear to be influenced by analyzed clinical variables.

Effect of casein phosphopeptide-amorphous calcium phosphate as a remineralizing agent - An In Vivo study

Introduction

Demineralization and remineralization have a crucial impact on the hardness and strength of teeth. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) Trident white chewing gum has anticariogenic property and also stimulates saliva, which buffers the oral cavity and promotes remineralization. Trident sugar-free gum, therefore, is an excellent delivery vehicle for promoting enamel remineralization.

Aims and Objectives

The aim of this study is to show that CPP-ACP-containing chewing gum would increase the level of calcium concentration of saliva, thereby supplying calcium and phosphorus to whole dentition for a prolonged period and aid in remineralization of tooth surfaces.

Materials and Methods

An in vivo nonrandomized clinical trial study was carried among 60 children. Unstimulated saliva from each 60 selected participants was collected. Then each participant was given two pellets of chewing gum containing CPP-ACP and asked to chew for a period of 20 min, after which saliva samples were again collected from each participant. The study was carried out for 15 days, and at three intervals, calcium and phosphorus levels were assessed using affiliated reagent kits and spectrophotometer.

Results

Significant difference was found in the calcium and phosphorus concentration of saliva before and after chewing CPP-ACP-containing chewing gum. When post calcium and phosphate levels were analyzed among different time intervals, a highly statistically significant difference was observed (P = 0.000).

Conclusion

Clinical trial study shows that chewing sugar-free gum containing CPP-ACP can be regarded as an additional caries prevention tool.

A comparison of antibacterial inhibitory effect on Streptococcus mutans and tensile strength between chitosan-based bonding adhesives and commercial products

Background

Adhesive bonding is the material used to attach a bracket to the enamel surface of the tooth. Streptococcus mutans contributes to enamel demineralization during orthodontic treatment.

Objectives

To analyze the antimicrobial inhibitory effect of Streptococcus mutans bacteria and tensile strength of chitosan and CaCO₃-based adhesive bonding material.

Materials and Methods

The investigation constituted laboratory experimental research featuring analytical observation and a random sampling method. The antibacterial inhibitory effect of chitosan and CaCO₃-based adhesive bonding against Streptococcus mutans involved six groups: two control groups using commercial light cure and self-cure adhesive bonding products and four groups using adhesive bonding consisting of 75% CaCO₃ + 17.6% Bis-GMA + 22.4% MMA with various percentages of chitosan composition (A1: 25%, A2: 50%, A3: 75%, and A4: 100%) each group consisting of two samples (n = 12). A diametric test was conducted consisting of three samples (n = 15) to measure the tensile strength of each group. Data were analyzed by a combination of one-way analysis of variance and least significant difference tests.

Result

The antibacterial inhibitory effect showed significant differences between groups (A1: 2.9467 ± 0.4163, A2: 3.6500 ± 0.6245, A3: 5.1267 ± 0.2517, A4: 4.7267 ± 0.9238; P = 0.0000; P < 0.05). A diametric tensile strength test confirmed significant differences between groups (A1: 7.2733 ± 5.0046, A2: 6.7667 ± 4.4346, A3: 6.4533 ± 2.9994, A4: 1.0058 ± 1.0058, K1: 15.6167 ± 3.1250; P = 0.009; P < 0.05).

Conclusion

Chitosan-based adhesive bonding with good tensile strength has an antibacterial inhibitory effect against Streptococcus mutans.

Preventive effects of carbon dioxide laser and casein phosphopeptide amorphous calcium phosphate fluoride varnish on enamel demineralization: A comparative, in vitro study

AIM

The aim of the present study was to compare the effects of carbon dioxide (CO₂ ) laser and casein phosphopeptide amorphous calcium phosphate (CPP-ACP)fluoride varnish on enamel demineralization.

METHODS

Human teeth were randomly assigned to three groups. The enamel was treated with fluoride varnish, 10.6 μm CO₂ laser, or no treatment (control), followed by 9 days of pH cycling. Baseline and final FluoreCam images were used to quantify the area, intensity, and impact of demineralization; cross-sectional microhardness was used to measure the mechanical properties of the enamel.

RESULTS

There were statistically-significant changes in the area, intensity and impact of demineralization in the control and laser groups (P < 0.05), but not in the fluoride group. The control group showed a significantly greater area and impact of enamel demineralization compared to the fluoride group. The area of demineralization in the laser group was significantly greater than that of the fluoride group. Enamel demineralization of the laser and control groups was comparable. The fluoride group showed statistically-significant harder enamel than the control at 20, 40, and 60 μm depths; the laser group enamel was significantly harder than the control at 20 and 40 μm depths. The fluoride group showed statistically-significant harder enamel than the laser group at 20 μm depth.

CONCLUSIONS

CPP-ACP fluoride varnish is more effective than CO₂ in preventing enamel demineralization.

Enamel remineralization therapies for treating postorthodontic white-spot lesions: A systematic review

BACKGROUND

One of the adverse effects of orthodontic treatment is the appearance of white-spot lesions (WSLs) resulting from enamel demineralization. The objective of this systematic review was to investigate the effectiveness of remineralization therapies on WSLs after orthodontic treatment.

TYPES OF STUDIES REVIEWED

In this systematic review, the authors identified relevant articles listed in 5 databases-PubMed, the Cochrane Library, Scopus, Embase, and Web of Science-by using a combination of search terms referring to orthodontics, demineralization, and treatment. Ten articles on the efficacy of WSL remineralization therapies met the inclusion criteria.

RESULTS

Among the studies of remineralizing therapy, neither fluoride mouthrinses nor phosphopeptide toothpastes with or without fluoride had any positive effect in addition to oral hygiene maintenance with fluoride toothpaste. A 5% sodium fluoride varnish was the only therapy to show a statistically significant improvement compared with results in the control group. The authors found large variations in results among the studies reviewed because of the different methods used.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

None of the treatments was capable of remineralizing WSLs. A 5% sodium fluoride varnish could improve remineralization of WSLs.

Variation in Enamel Formation Genes Influences Enamel Demineralization In Vitro in a Streptococcus mutans Biofilm Model

Genetic studies have shown that variations in enamel formation genes are associated with caries susceptibility. The aim of this study was to test in vitro whether variants in these genes are associated with dental enamel demineralization in a Streptococcus mutans biofilm model. DNA and enamel samples were obtained from 213 individuals. DNA was extracted from saliva, and 16 single nucleotide polymorphisms were analyzed. The physical and chemical properties of sound enamel samples and the mineral loss and the lesion depth of the demineralized enamel samples under cariogenic challenge were analyzed. Microhardness, enamel chemicals, mineral loss and demineralization depth were compared between different genotypes at each single nucleotide polymorphism. The GG genotype of TUFT1 (rs17640579) and the GT genotype of MMP20 (rs1612069) exhibited increased microhardness (p = 0.044 and 0.016, respectively). The GG genotype of AMBN (rs7694409) had a higher magnesium level, while the CT genotype of TFIP11 (rs2097470) had a lower magnesium level (p = 0.044 and 0.046, respectively). The GT genotype of MMP20 (rs1612069) had a higher calcium level (p = 0.034). The GG genotype of AMBN (rs13115627), the AG genotype of ENAM (rs12640848) and the AA genotype of MMP20 (rs2292730) had a lower phosphorus level (p = 0.012, 0.006, and 0.023, respectively). The GG genotype of AMBN (rs13115627) was also associated with a higher calcium-phosphorus ratio (p = 0.034). Individuals with the CC genotype of TFIP11 (rs134143) exhibited significantly more mineral loss (p = 0.011) and a deeper lesions (p = 0.042). Individuals with the TT genotype of TFIP11 (rs2097470) had more mineral loss (p = 0.018). Individuals with the GG genotype of TUFT1 (rs17640579) exhibited a shallower demineralization depth (p = 0.047). Individuals with the GT genotype of MMP20 (rs1612069) exhibited a shallower demineralization depth (p = 0.042). Individuals with the GG genotype of ENAM (rs12640848) exhibited less mineral loss (p = 0.01) and a shallower demineralization depth (p = 0.03). Genetic variations in TFIP11, TUFT1, MMP20, and ENAM influenced enamel demineralization in a Streptococcus mutans biofilm model.

Comparative study of two chemical protocols for creating white spot lesions: An in vitro FluoreCam evaluation

AIM

The aim of the present study was to compare the effectiveness and practicality of two commonly-used protocols for white spot lesion creation.

METHODS

Sound posterior human teeth were sectioned into halves and randomly allocated into two groups (n=20). Using the FluoreCam system, the enamel surfaces were imaged under standardized conditions, and baseline data (area, intensity, and impact) were recorded. Specimens were covered with an acid-resistant polish, leaving a 2×6-mm enamel window. Group 1 was immersed in Queiroz solution (64 hours/37°C/pH5 with agitation); Group 2 was immersed in Buskes solution (14 days/37°C/pH5 with agitation). The specimens then were imaged again. Within-group changes that occurred over time were evaluated using the Wilcoxon signed-rank test. Between-group differences were analyzed using the Mann-Whitney U-test. Polarized light microscopy (PLM) was used to calculate the mean lesion depth of representative specimens.

RESULTS

Each protocol showed significant changes in the surface area, intensity and impact of demineralization over time (P<.05). There were no statistically-significant differences (P=.53, P=.2, P=.74) between the two groups. PLM showed that the mean lesion depths of representative specimens were 51.4 and 73.0 μm for groups 1 and 2, respectively.

CONCLUSIONS

While both protocols produce similar amounts of demineralization, the Queiroz solution is more practical, as it requires less time.

Effect of Nd:YAG and CO2 Laser Irradiation on Prevention of Enamel Demineralization in Orthodontics: In Vitro Study

OBJECTIVE

The aim of this study was to investigate Nd:YAG and CO₂ laser effects in the prevention of demineralization in deeper layers of enamel via successive acid challenge cycles.

BACKGROUND DATA

Lasers are promising in the prevention of enamel demineralization around the orthodontic brackets; however, there are very few studies that evaluate if the effects of treatment could be extended after successive acid challenge cycles due to permanent enamel structural alterations.

MATERIALS AND METHODS

Human enamel samples were divided into five groups (n = 12): G1-application of 1.23% acidulated fluoride phosphate gel (AFP, control); G2-Nd:YAG laser irradiation (0.6 W, 84.9 J/cm², 10 Hz, 110 μs, contact mode); G3-Nd:YAG laser irradiation associated with AFP; G4-CO₂ laser irradiation (0.5 W, 28.6 J/cm², 50 Hz, 5 μs, and 10 mm focal distance); and G5-CO₂ laser irradiation associated with AFP. The samples were submitted to successive acid challenge cycles. Quantitative light-induced fluorescence and scanning electron microscopy were used to assess enamel demineralization. The data were statistically compared (α = 5%).

RESULTS

G1: 50.87 ± 4.57; G2: 47.72 ± 2.87; G3: 50.96 ± 4.01; G4: 28.21 ± 2.19; and G5: 30.13 ± 6.38. The CO₂ laser groups had significantly lower mineral losses than those observed in all other groups after successive acid challenge cycles.

CONCLUSIONS

Only the CO₂ laser (10.6 μm) irradiation prevents enamel demineralization around the orthodontic brackets even after exposure to successive acid challenges. The CO₂ laser at 10.6 μm showed a deeper effect in enamel regarding caries prevention.

An in vitro dynamic microcosm biofilm model for caries lesion development and antimicrobial dose-response studies

Some dynamic biofilm models for dental caries development are limited as they require multiple experiments and do not allow independent biofilm growth units, making them expensive and time-consuming. This study aimed to develop and test an in vitro dynamic microcosm biofilm model for caries lesion development and for dose-response to chlorhexidine. Microcosm biofilms were grown under two different protocols from saliva on bovine enamel discs for up to 21 days. The study outcomes were as follows: the percentage of enamel surface hardness change, integrated hardness loss, and the CFU counts from the biofilms formed. The measured outcomes, mineral loss and CFU counts showed dose-response effects as a result of the treatment with chlorhexidine. Overall, the findings suggest that biofilm growth for seven days with 0.06 ml min(-1) salivary flow under exposure to 5% sucrose (3 × daily, 0.25 ml min(-1), 6 min) was suitable as a pre-clinical model for enamel demineralization and antimicrobial studies.

Effects of fluoride release from orthodontic bonding materials on nanomechanical properties of the enamel around orthodontic brackets

BACKGROUND

The aim of the present study is to evaluate the effects of a fluoride-releasing composite resin bonding material on reducing enamel demineralization underneath and around orthodontic brackets and compare that with a conventional adhesive system.

MATERIALS AND METHODS

Buccal surfaces of 10 intact extracted premolar teeth were divided into two parts with nail varnish and stainless steel brackets were randomly bonded by two resin composite systems: (Transbond XT) and (Transbond XT plus Color Change) (3M, Unitek, Monrovia, CA, USA) on two sides of the teeth and then samples were placed in a demineralization solution. It is claimed that the second system has the ability of fluoride release. Elastic modulus and hardness of enamel were measured with nanoindentation test in 6 depths in 1-36 μm from the enamel surface and in 7 regions: Control (intact enamel surface), underneath the brackets and also 50 and 100 μm from the brackets edge. These nanomechanical features were evaluated in different regions and depths using analysis of variance and paired t-test (P < 0.05).

RESULTS

Considerable difference can be seen in different depths and regions in terms of hardness and elastic modulus. The region under the bracket with fluoridated adhesive shows similar results with intact enamel, whereas these parameters in fluoride less side show a significant reduction (P < 0.05).

CONCLUSION

Results show that use of resin composite bonding system with the ability of fluoride release for bracket bonding, may reduce demineralization of enamel around brackets during orthodontic treatment.

Can white spot lesions be treated effectively?

OBJECTIVE

To compare the effects of sodium fluoride mouth rinse, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and the microabrasion technique in treating white spot lesions.

MATERIALS AND METHODS

The study population consisted of 80 patients (46 females, 34 males; 966 affected teeth) who had developed multiple decalcified enamel lesions after fixed orthodontic therapy. The study population was divided into four groups of 20 patients each. The control group (group I) participants were to just brush their teeth, the fluoride group (group II) participants were instructed to use 20 ml of neutral 0.025% sodium fluoride rinse, the participants in the CPP-ACP group (group III) were instructed to use tooth mousse twice a day in addition to fluoride toothpaste for 6 months, and the participants in the microabrasion group (group IV) were to undergo treatment by the microabrasion technique, which is a commonly used mixture of 18% hydrochloric acid. Data were analyzed with the generalized linear mixed model and Tukey HSD at the P < .05 level.

RESULTS

The area of the white spot lesions decreased significantly in all groups. Inter group differences in the treatment success rates were significant. The highest success rate was observed for group IV (97%). The success rate of group III (58%) was significantly higher than that of groups II (48%) and I (45%).

CONCLUSIONS

The use of CPP-ACP can be more beneficial than fluoride rinse for postorthodontic remineralization. Microabrasion is an effective treatment for cosmetic improvement of long-standing white spot lesions.

A comparison of methods using optical coherence tomography to detect demineralized regions in teeth

Optical coherence tomography (OCT) is a three- dimensional optical imaging technique that can be used to identify areas of early caries formation in dental enamel. The OCT signal at 850 nm back-reflected from sound enamel is attenuated stronger than the signal back-reflected from demineralized regions. To quantify this observation, the OCT signal as a function of depth into the enamel (also known as the A-scan intensity), the histogram of the A-scan intensities and three summary parameters derived from the A-scan are defined and their diagnostic potential compared. A total of 754 OCT A-scans were analyzed. The three summary parameters derived from the A-scans, the OCT attenuation coefficient as well as the mean and standard deviation of the lognormal fit to the histogram of the A-scan ensemble show statistically significant differences (p < 0.01) when comparing parameters from sound enamel and caries. Furthermore, these parameters only show a modest correlation. Based on the area under the curve (AUC) of the receiver operating characteristics (ROC) plot, the OCT attenuation coefficient shows higher discriminatory capacity (AUC = 0.98) compared to the parameters derived from the lognormal fit to the histogram of the A-scan. However, direct analysis of the A-scans or the histogram of A-scan intensities using linear support vector machine classification shows diagnostic discrimination (AUC = 0.96) comparable to that achieved using the attenuation coefficient. These findings suggest that either direct analysis of the A-scan, its intensity histogram or the attenuation coefficient derived from the descending slope of the OCT A-scan have high capacity to discriminate between regions of caries and sound enamel.

Ability of optical coherence tomography to detect caries beneath commonly used dental sealants

BACKGROUND AND OBJECTIVE

The onset and progression of early tooth decay is often preventable with dental sealants. However, occasionally decay progresses underneath the sealant. Current technology does not permit monitoring of potential lesion progression or arrest. Dental sealants themselves mask the visual cues that identify early tooth decay, and radiographs are not sufficiently sensitive. Therefore, clinicians can be reluctant to use dental sealant. The objective of this ex vivo study was to evaluate the ability of dentists to detect decay beneath commonly used dental sealants using optical coherence tomography (OCT) imaging. STUDY DESIGNS/MATERIALS/METHODS: Forty extracted teeth were divided into equal groups of carious and non-carious teeth, as determined by visual inspection. After radiographs and OCT imaging, teeth were randomly assigned for sealant placement with one of four commonly purchased dental sealants: Clinpro™, Fuji Triage™, Embrace Wet Bond™, and Delton™.Following sealant placement, teeth were radiographed, imaged with OCT, sectioned, examined histologically, and scored as healthy/not healthy. OCT and radiographic images were scored separately. The gold standard was histopathological diagnosis from the serial sections.Cohen's kappa, sensitivity, negative predictive value, and positive predictive value were computed for all measures.

RESULTS

After 90 minutes training, pre-standardized dentists were able to detect tooth decay more accurately using OCT than with visual or radiographic examination. Detection using OCT was somewhat better prior to sealant placement than afterwards. This effect varied in size depending on the type of sealant used. Radiographic diagnosis was also less accurate after sealant placement. Of the four dental sealants, Delton provided excellent positive predictive value and the best post-sealant negative predictive values.

CONCLUSION

In this ex vivo study, dentists were able to detect tooth decay beneath four commonly used dental sealants based on OCT images. Clinical investigations are now underway to determine the usefulness of this approach in vivo.

Assessment of early demineralization in teeth using the signal attenuation in optical coherence tomography images

Optical coherence tomography imaging is used to improve the detection of incipient carious lesions in dental enamel. Measurements of signal attenuation in images acquired with an 850-nm light source were performed on 21 extracted molars from eight human volunteers. Stronger attenuation was observed for the optical coherence tomography (OCT) signal in healthy enamel than in carious lesions. The measured attenuation coefficients from the two groups form distinct statistical populations. The coefficients obtained from sound enamel fall within the range of 0.70 to 2.14 mm(-1) with a mean value of 1.35 mm(-1), while those in carious regions range from 0.47 to 1.88 mm(-1), with a mean value of 0.77 mm(-1). Three values are selected as the lower threshold for signal attenuation in sound enamel: 0.99, 0.94, and 0.88 mm(-1). These thresholds were selected to provide detection of sound enamel with fixed specificities of 90%, 95%, and 97.5%, respectively. The corresponding sensitivities for the detection of carious lesions are 92.8%, 90.4%, and 87%, respectively, for the sample population used in this study. These findings suggest that attenuation of OCT signal at 850 nm could be an indicator of tooth demineralization and could be used as a marker for early caries detection.