Remineralization of deep enamel dentine caries lesions

Comparison of the Diagnostic Accuracy of an AI-Based System for Dental Caries Detection and Clinical Evaluation Conducted by Dentists

Background/Objectives: Artificial intelligence (AI)-based software is increasingly used for radiographic analysis in dentistry. This study aimed to evaluate the diagnostic accuracy of an AI-powered radiographic analysis system, using Diagnocat (DGNCT LLC, Miami, FL, USA) as an example, compared with clinical evaluations performed by three experienced dentists. The assessment focused on primary caries detection and the total number of primary and secondary caries based on panoramic radiographs (OPGs). Methods: Three dentists with similar expertise independently classified teeth for treatment using only panoramic radiographs and their clinical knowledge. The study was conducted under single-blind conditions, where clinicians were unaware that their diagnoses would be compared to the AI system's analysis. Results: The AI system's agreement with human evaluations varied depending on tooth location, patient age, and gender. The lowest agreement was observed for premolars, likely due to limitations of 2D imaging, while higher accuracy was found for molars and incisors, particularly in younger patients. The system showed limitations in detecting occlusal, labial, and lingual caries. Conclusions: AI-assisted radiographic analysis has the potential to enhance diagnostic efficiency and automation in dentistry. However, its accuracy is influenced by tooth location and imaging modality. Further research is needed to explore the benefits of integrating AI with 3D imaging techniques to improve diagnostic reliability.

Efficacy of Sodium Fluoride and Fluoridated Calcium Phosphate in Mitigating Dental Erosion on Human Enamel: An In Vitro Analysis

INTRODUCTION

With increasing prevalence of dental erosion, this study explores the protective role of traditional fluoride-based products and newer formulations on eroded enamel.

AIMS

To assess the protective effectiveness of casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) and sodium fluoride (NaF) on human enamel against erosion using surface microhardness (SMH) and Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses.

MATERIALS AND METHODS

Ten extracted human third molars were sectioned to obtain 40 enamel sections and randomly assigned into four groups (n = 10) and treated as follows: G1 (Sound Enamel), G2 (Erosive Challenge), G3 (CPP-ACPF + Erosive Challenge), and G4 (NaF + Erosive Challenge). All samples were subjected to Vicker's SMH analysis, while changes in surface morphology and elemental composition were validated in few representative samples using FTIR and SEM, respectively.

STATISTICAL ANALYSIS

Paired samples test, Kruskal-Wallis test, and Tukey HSD test were performed using SPSS software version 23 setting P value < 0.05 as statistically significant.

RESULTS

The mean SMH1 values for the experimental groups G3 and G4 were significantly higher (426.58VHN and 455.83VHN) when compared to G1 (P = 0.000) and G2 (P = 0.000). In SEM analysis, G2 showed eroded honeycomb appearance compared to the smooth homogenous surface of G1, while both G3 and G4 showed deposition of some precipitates. FTIR analysis revealed that in G3 and G4, a characteristic peak of phosphate vibrations between 528 and 823 cm-1 and carbonate bands at 845-932 cm-1 was observed.

CONCLUSIONS

Both CPP-ACPF and NaF demonstrated a protective effect on enamel against erosive challenge by an orange juice-based beverage.

Remineralization Effect of Bioactive Glass With and Without Fluoride and Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) on Artificial Dentine Caries: An In Vitro Study

Background/objectives Dentine hypersensitivity (DH) is a common dental condition marked by transient, sharp pain arising from dentinal exposure. Bioactive materials are capable of remineralization. This study aims to explore the remineralization effect of bioactive glass (BAG) with and without fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), using dentine discs as the test substrate. Materials and methods In this in vitro experimental study, 28 dentine discs were prepared from premolar teeth. Artificial caries were induced by subjecting the dentine discs to demineralization in acid for 72 hours. After demineralization, the discs were treated with various remineralizing dentifrices to evaluate their effects. The dentine discs (n=28) were divided into four groups: group 1 = BioMin (BioMin Technologies, London, United Kingdom), group 2 = NovaMin/Sensodyne Repair (GlaxoSmithKline plc, London, England, United Kingdom), group 3 = Recaldent (CPP-ACP; GC Orthodontics Inc., Alsip, Illinois, United States), and group 4 = deionized water (control group). All discs underwent a 28-day remineralization process using the respective dentifrices assigned to each group. The microhardness of the discs was measured using Vickers microhardness testing at three stages: baseline, post-demineralization, and post-remineralization. Results There was no significant difference in terms of microhardness between groups both at the baseline (F (3, 24) = 1.079, p = 0.995) and after the demineralization process (F (3, 24) = 1.310, p = 0.294). However, a significant difference was identified between the groups after the remineralization process (F (3, 24) = 34.008, p = 0.001). Additionally, the least significant difference (LSD) multiple comparison test was performed. There were significant differences identified in the remineralization condition, with group 1 having the highest values, followed by group 2, group 3, and group 4. Conclusion The results indicate that the remineralization effect on artificially induced dentine caries was more pronounced with bioactive glass containing fluoride compared to bioactive glass without fluoride and CPP-ACP.

Protective effect of various toothpastes and mouthwashes against erosive and abrasive challenge on eroded dentin: an in vitro study

The study aimed to compare various toothpastes and mouthwashes on permanent tooth dentin after erosive and abrasive challenges. 130 sound premolars dentin were randomly submitted to an initial erosive challenge and a cycle of erosive and abrasive challenges for five days. The five experimental groups (n = 26) were: (1) Control group (artificial saliva), (2) Elmex erosion protection toothpaste and mouthwash, (3) Vitis anticaries biorepair toothpaste and mouthwash, (4) Oral B Pro-expert toothpaste and Oral B Fluorinse mouthwash, and (5) MI Paste ONE toothpaste and Caphosol mouthwash. Microhardness, surface roughness values, and the topographical characteristics of the dentin surface were assessed. The highest percentage of recovered dentin microhardness (%RDMH) value was observed in groups 2 and 4, followed by groups 5 and 3, respectively. The %RDMH values in groups 2 and 4 did not demonstrate a significant difference (p = 0.855). The highest percentage of improvement in surface roughness was recorded in groups 2 and 4, with no significant differences (p = 0.989). The atomic force microscopy (AFM) findings were consistent with the surface roughness data. The best recovery of dentin microhardness and roughness were measured with the Elmex and Oral B toothpaste and mouthwash, followed by MI Paste ONE toothpaste and Caphosol mouthwash and Vitis anticaries biorepair toothpaste and mouthwash.

Comparison of different bioglass applications on root caries – A laboratory-based study

The aim of this in-vitro study was to assess the effect of bioglass with different concentrations on root caries.

Ninety freshly-extracted teeth with root caries were randomly assigned to a single-use prophylaxis paste containing 15 % bioglass for 30 s with 1,450 ppmF toothpaste (15 % bioglass, n = 30), 1,450 ppmF toothpaste with 5 % bioglass (5 % bioglass, n = 30), and toothpaste containing 1,450 ppmF (Control, n = 30). Each sample received a standard brushing procedure for 10 s twice a day using the toothpastes. Teeth were immersed in remineralising solution with pH of 7 at 37 °C for 720 h. Surface roughness (Ra) was measured at baseline and after the application of the products at 0.5, 1, 4, 12, 24, 48, 168, 336 and 720 h. Subsequently, three samples from each group were randomly selected to measure calcium ion release over 15 h immersion in deionised water. These samples were then analysed using the SEM for the qualitative assessment of lesion topography. Repeated measures ANOVA, Wilcoxon paired tests and percentage changes were carried out to assess Ra. Calcium ion release data was analysed using one-way ANOVA and Tukey post-hoc tests.

After 720 h, 15 % bioglass had the highest decrease in Ra (Mean-difference = 1.502 µm, p = 0.001), then 5 % bioglass (Mean-difference = 0.723 µm, p = 0.09) whereas the control had the lowest Ra decrease (Mean-difference = 0.518 µm, p = 0.55). The differences in Ra between the groups were highly significant (p < 0.001). The cumulative calcium ion release was significantly high for the 5 % bioglass in comparison to the 15 % bioglass, whilst the control had the lowest release (p < 0.001). SEM analysis showed the presence of bioglass particles only on 15 % bioglass samples.

The use of prophylaxis paste with 15 % bioglass and 1,450 ppmF toothpaste was promising to reverse/arrest root caries when compared to the toothpaste containing 1,450 ppmF with 5 % bioglass for a period of 30 days.

Progress on Biomimetic Mineralization and Materials for Hard Tissue Regeneration

Biomineralization is a process in which natural organisms regulate the crystal growth of inorganic minerals, resulting in hierarchical structured biominerals with excellent properties. Typical biominerals in the human body are the bones and teeth, and damage to these hard tissues directly affect our daily lives. The repair of bones and teeth in a biomimetic way, either by using a biomimetic mineralization strategy or biomimetic materials, is the key for hard tissue regeneration. In this review, we briefly introduce the structure of bone and tooth, and highlight the fundamental role of collagen mineralization in tissue repair. The recent progress on intra-/extrafibrillar collagen mineralization by a biomimetic strategy or materials is presented, and their potential for tissue regeneration is discussed. Then, recent achievements on bone and tooth repair are summarized, and these works are discussed in the view of materials science and biological science, providing a broader vision for the future research of hard tissue repair techniques. Lastly, recent progress on hard tissue regeneration is concluded, and existing problems and future directions are prospected.

Effects of a biomimetic analog-based experimental bonding system on caries-affected and sound dentin

This study compared the ultrastructure, chemical composition, and proteases activity (PA) of sound (SD) and caries-affected dentin (CAD) in the dentin hybrid layer after using an experimental bonding system containing pyromellitic dianhydride glycerol methacrylate and biomimetic analogs. The bonding system used a three step and a total-etch procedure. Polyacrylic acid (5%) and sodium trimetaphosphate (5%) were added to the primer and monocalcium phosphate monohydrate (9%), beta-tricalcium phosphate (10.5%), and calcium hydroxide (0.5%) were added to the adhesive. Transmission electron microscopy (TEM) was used to evaluate the resultant structure, particularly the adhesive-dentin and the demineralized-SD interfaces. The chemical composition was evaluated through energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). The PA was measured with the Coomassie Blue-G250 coloring test, and the PA data were analyzed by ANOVA. EDS identified the presence of isolated calcium phosphate nanoparticles in the demineralized region; however, the SAED analysis did not show any evidences of hydroxyapatite (HA) neoformation in SD and CAD. The biomimetic analog-based adhesive system inhibited the activities of dentin proteases immediately after treatment. Additionally, the proteolytic activity on the affected dentin resembled that of the SD. In conclusion, no HA formed in the demineralized SD and CAD although there were calcium and phosphate deposits. The experimental adhesive system inhibited dentin proteases. The present study uses a new approach to investigate the hybrid layer behavior in dentin. The experimental adhesive system was synthesized and used on sound and affected-caries dentin as the substrate to reproduce real clinical conditions.

Comparative Evaluation of the Remineralizing Potential of Commercially Available Agents on Artificially Demineralized Human Enamel: An In vitro Study

Background

Caries is highly prevalent multifactorial disease, but its progression can be prevented in the initial stage of demineralization through remineralization (RML). Various materials have been proposed for the same, successful outcome can prove to be a boon in the prevention of caries.

Aim

The aim of the study is to assess the RML potential of four commercially available agents so as to restore the enamel closest to its previous microhardness levels.

Materials and Methods

Sixty permanent intact premolars were randomly divided into six groups: Four test groups - (1) bioactive glass (BAG) Novamin (SHY-NM), (2) nano-hydroxyapatite (nHAp) (Acclaim), (3) functionalized tricalcium phosphate (f-TCP) (Clinpro Tooth Crème), and (4) grape seed extract (GSE); one positive control - (5) fluoride (1000 ppm) containing dentifrice (Colgate Calci-Lock); and one negative control - (6) distilled water. The samples were initially evaluated for baseline surface microhardness (SMH); later on, these samples were placed in the demineralizing solution for 48 h in an incubator at 37°C, and postdemineralization again SMH was measured. Thereafter, the samples were subjected to the pH cycling for consecutive 21 days, and SMH was recorded. The SMH was evaluated using a Vickers microhardness tester. Statistical analysis was done using a post hoc Tukey test for each group based on the stage of treatment and one-way ANOVA for comparison among different groups.

Results

BAG Novamin showed SMH recovery at 96.75% followed by f-TCP at 95.83%, nHAp at 90.88%, and GSE at 48.71%. Statistically significant differences were observed between the first three groups and the rest of the groups after RML stage.

Conclusion

BAG Novamin, f-TCP, and nHAp showed considerable RML followed to a lesser extent by GSE.

The Efficacy of Resin Infiltrant and Casein Phosphopeptide-amorphous Calcium Fluoride Phosphate in Treatment of White Spot Lesions (Comparative Study)

Background:

White spot lesions (WSLs) are considered as the first sign of the progression of dental caries that can be reversed. Casein phosphopeptide–amorphous calcium fluoride phosphate (CPP-ACFP) varnish can promote remineralization process of the demineralized tooth structure. Also, WSLs can be managed by using caries infiltrant (ICON), which infiltrates etched enamel surface of the WSLs.

Objectives:

The main aim was to evaluate and compare the efficacy of ICON versus CPP-ACFP varnish to treat WSLs in the same oral environments.

Materials and Methods:

A total of 30 participants aged 20–40 years with at least two WSLs have participated in this trial. Split-mouth technique has been used in this trial where WSLs on the left side have been treated with ICON, whereas WSLs on the right side have been treated with CPP-ACFP varnish. Clinical evaluation using DIAGNOdent was carried out at baseline, 1 week, 1, 3, 6, and 12 months after application to determine the effectiveness of these materials in treating WSLs.

Results:

Significant differences were observed between all follow-up DIAGNOdent scores compared to baseline readings of both ICON and CPP-ACFP (P = 0.000 for all comparisons). Statistically significant differences were observed between DIAGNOdent scores of ICON compared to CPP-ACFP at all follow-up intervals (P = 0.006, 0.008, 0.045, 0.036, and 0.000).

Conclusion:

Both ICON and CPP-ACFP were effective in the treatment of WSLs of smooth surfaces but the efficacy of CPP-ACFP was better than ICON.

Remineralising effect of 45S5 bioactive glass on artificial caries in dentine

BACKGROUND

This study investigated the remineralisation effect of bioactive glass on artificial dentine caries.

METHODS

Dentine disks with artificial caries were treated with bioactive glass (group BAG), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (group CPP-ACP), sodium fluoride glycerol (group F) or deionized water (group W). All disks were subjected to pH cycling for 28 days subsequently. The topography, microhardness and remineralisation depth of the dentine carious lesion were assessed by atomic force microscopy (AFM), microhardness testing and confocal laser scanning microscope (CLSM), respectively.

RESULTS

AFM images indicated mineral depositions on the surface of the carious lesion in group BAG. The changes of Vickers hardness number (ΔVHN, mean ± SD) after pH cycling were 9.67 ± 3.60, 6.06 ± 3.83, 5.00 ± 2.19 and - 1.90 ± 2.09 (p < 0.001) in group BAG, group CPP-ACP, group F and group W, respectively. The remineralisation depth (mean ± SD) of the carious lesion in group BAG, group CPP-ACP, group F and group W were 165 ± 11 μm, 111 ± 11 μm, 75 ± 6 μm and 0 μm (p < 0.001), respectively.

CONCLUSION

Bioactive glass possessed a promising remineralisation effect on artificial dentine caries and could be a therapeutic choice for caries management.

Remineralization of Demineralized Enamel and Dentine Using 3 Dentifrices-An InVitro Study

Objectives: To monitor the electrical resistance of artificially demineralized enamel and root dentine after exposure to different fluoridated dentifrices and, using transversal microradiography, to quantify remineralization. Materials and methods: This in-vitro blind investigation used 20 extracted teeth (four groups of five each). Each group was exposed to one test dentifrice [Colgate PreviDent (5000 ppm F), Colgate Winterfresh gel (1100 ppm F), Fluocaril Bi-Fluoré (2500 ppm F) and placebo (without fluoride)] three times daily for three minutes for 4 weeks. In between exposure to the test dentifrices, teeth were stored in a saliva storage solution. An Electrical Caries Monitor measured the electrical resistance at baseline and during the four-week test period at weekly intervals. The measurements were log transformed and Duncan's multiple range test applied. Remineralization was quantified using transversal microradiography. Results: Log mean (SD) electronic carries monitor (ECM) measurements in enamel at baseline and after 4 weeks of exposure to the test dentifrices were 4.07(1.53) and 3.87(0.90) (Placebo-Fluocaril), 4.11(1.86) and 4.64(1.43) (Colgate Winterfresh gel), 4.81(0.9) and 4.21(1.20) (Fluocaril Bi-Fluoré), and 4.60(0.88) and 3.76(0.9) (Colgate PreviDent). Corresponding measurements in dentine were 2.13(0.89) and 3.06(0.87) (Placebo-Fluocaril), 1.87(0.63) and 2.88(1.32) (Colgate Winterfresh gel), 2.47(1.20) and 1.65(0.60) (Fluocaril), and 2.16(0.00), and 2.34(1.07) for Colgate PreviDent. Lesion depth (µm) after microradiography in enamel was 100.1 (Placebo), 50.6 (Colgate Winterfresh gel), and 110.2 (Fluocaril, and 97.1 (Colgate PreviDent), and corresponding values in dentine were 169.7, 154.8, 183.7, and 153.5. The correlation of ECM and microradiographic parameters was negative (p < 0.05). Conclusion: Exposure of artificially demineralized enamel and root dentine to fluoridated dentifrices and saliva storage solution resulted in remineralization as follows: Colgate Winterfresh > Colgate PreviDent > Placebo-Fluocaril > Fluocaril Bi-Fluoré. Remineralization in teeth of the Placebo dentifrice group may be attributed to the presence of calcium and phosphate ions in the saliva storage solution.

Remineralization, Regeneration, and Repair of Natural Tooth Structure: Influences on the Future of Restorative Dentistry Practice

Currently, the principal strategy for the treatment of carious defects involves cavity preparations followed by the restoration of natural tooth structure with a synthetic material of inferior biomechanical and esthetic qualities and with questionable long-term clinical reliability of the interfacial bonds. Consequently, prevention and minimally invasive dentistry are considered basic approaches for the preservation of sound tooth structure. Moreover, conventional periodontal therapies do not always ensure predictable outcomes or completely restore the integrity of the periodontal ligament complex that has been lost due to periodontitis. Much effort and comprehensive research have been undertaken to mimic the natural development and biomineralization of teeth to regenerate and repair natural hard dental tissues and restore the integrity of the periodontium. Regeneration of the dentin-pulp tissue has faced several challenges, starting with the basic concerns of clinical applicability. Recent technologies and multidisciplinary approaches in tissue engineering and nanotechnology, as well as the use of modern strategies for stem cell recruitment, synthesis of effective biodegradable scaffolds, molecular signaling, gene therapy, and 3D bioprinting, have resulted in impressive outcomes that may revolutionize the practice of restorative dentistry. This Review covers the current approaches and technologies for remineralization, regeneration, and repair of natural tooth structure.

Comparison of the Efficacy of Different Fluoride Varnishes on Dentin Remineralization During a Critical pH Exposure Using Quantitative X-Ray Microtomography

OBJECTIVES:

The objective of this in vitro study was to quantify the amount of mineral change in demineralized dentin at pH 5.5 after the application of dental varnishes containing fluoride with casein phosphopeptide-amorphous calcium phosphate, fluoride and bioglass, or fluoride alone.

METHODS AND MATERIALS:

A total of 12 extracted human sound mandibular premolar root samples were coated with an acid-resistant varnish, leaving a 2 × 3 mm window at the outer root surface. These root specimens were then randomly divided into four groups and separately subjected to the demineralizing cycle at a pH of 4.8 for five days to create artificial caries-like lesions in dentin. Subsequently, each sample was imaged using quantitative x-ray microtomography (XMT) at a 15-μm voxel size. Each test group then received one of the following treatments: dental varnish containing casein phosphopeptide-amorphous calcium phosphate and fluoride (CPP-ACP, MI varnish, GC Europe), bioglass and fluoride (BGA, Experimental, Dentsply Sirona), or fluoride alone (NUPRO, Dentsply Sirona), as well as a control group, which received no treatment. These samples were kept in deionized water for 12 hours. The thin layer of varnish was then removed. All samples including the nonvarnish group were subjected to the second demineralizing cycle at pH 5.5 for five days. The final XMT imaging was then carried out following the second demineralizing cycle. XMT scan was also carried out to varnish samples at 25 μm voxel size. The change in mineral concentration in the demineralized teeth was assessed using both qualitative and quantitative image analysis.

RESULTS:

There was an increase in radiopacity in the subtracted images of all varnish groups; a significant increase in mineral content, 12% for the CPP-ACP and fluoride ( p≤0.05 and p≤0.001), 25% BGA ( p≤0.001), and 104% fluoride alone varnish ( p≤0.001). There was an increase in the size of radiolucency in the lesion area with a significant decrease in mineral content in the nonvarnish group, 10% ( p≤0.05 and p≤0.001).

CONCLUSIONS:

There was encouraging evidence of a remineralization effect following the application of dental varnish on dentin and also an observed resistance to demineralization during the acidic challenge in all cases. However, a dental varnish containing fluoride alone appeared to have a much greater effect on dentin remineralization when compared with CPP-ACP with fluoride and bioglass with fluoride.

In situ monitoring and analysis of enamel demineralisation using synchrotron X-ray scattering

Dental caries is one of the most common chronic diseases that affect human teeth. It often initiates in enamel, undermining its mechanical function and structural integrity. Little is known about the enamel demineralisation process caused by dental caries in terms of the microstructural changes and crystallography of the inorganic mineral phase. To improve the understanding of the carious lesion formation process and to help identify efficient treatments, the evolution of the microstructure at the nano-scale in an artificially induced enamel erosion region was probed using advanced synchrotron small-angle and wide-angle X-ray scattering (SAXS and WAXS). This is the first in vitro and time-resolved investigation of enamel demineralisation using synchrotron X-ray techniques which allows in situ quantification of the microstructure evolution over time in a simulated carious lesion. The analysis revealed that alongside the reduction of mineral volume, a heterogeneous evolution of hydroxyapatite (HAp) crystallites (in terms of size, preferred orientation and degree of alignment) could be observed. It was also found that the rate and direction of dissolution depends on the crystallographic orientation. Based on these findings, a novel conceptual view of the process is put forward that describes the key structural parameters in establishing high fidelity ultrastructure-based numerical models for the simulation of the enamel demineralisation process.

STATEMENT OF SIGNIFICANCE

Hydroxyapatite (HAp) crystallites in the enamel dissolve during dental caries although little is known about the structural-chemical relationships that control the dynamic demineralisation process. For the first time this work investigated the in situ evolution of nano-scale morphology and the spatial distribution of ultrastructural HAp crystallites of human enamel during demineralisation in simulated caries. Advanced synchrotron SAXS and WAXS techniques showed that the heterogeneous evolution of crystallites (size, preferred orientation and degree of alignment) could be attributed to crystallographic-orientation-dependent anisotropic dissolution. Hence we propose a novel conceptual schematic diagram to describe the demineralisation process. These findings have important implications for understanding the detailed mechanisms of enamel demineralisation and provide insight into potential enamel remineralisation that could restore structural integrity and function.

Remineralization Efficacy of an Amelogenin-Based Synthetic Peptide on Carious Lesions

Objective: The aim of this study was to evaluate the remineralization efficacy of an amelogenin-based peptide on initial enamel carious lesions in vitro. Furthermore, we attempted to provide insights into the possible mechanism of the remineralization, including determining the calcium-binding properties of the peptide and its effects on calcium phosphate mineralization.

Methods: The peptide comprising the N-terminus and the C-terminus of porcine amelogenin was synthesized by Synpeptide Co., Ltd. Fifty specimens were randomly assigned to five immersing treatment groups for 12 days: remineralizing medium only; 12.5 μg/mL peptide + remineralizing medium; 25 μg/mL peptide + remineralizing medium; 50 μg/mL peptide + remineralizing medium; fluoride + remineralizing medium. After immersion, mean mineral loss before and after remineralization of each specimen was determined using micro-CT. Mean mineral gain after remineralization was calculated. Calcium binding properties were measured by Isothermal titration calorimetry (ITC). TEM and Fourier transform-infrared were used to determine the effects of the peptide on calcium phosphate mineralization.

Results: A significant decrease in mineral loss after remineralization process in all groups was observed (p < 0.05). Treatment in remineralizing medium resulted in the lowest mineral gain while the fluoridated treatment exhibited the highest mineral gain among all groups. Inclusion of synthetic peptide in the remineralizing medium exhibited a higher mineral gain and the gain of 50 μg/mL group was greater than that of the 25 μg/mL group. No significant difference in mineral gain was observed between the remineralizing medium only group and the 12.5 μg/mL peptide group (p > 0.05). ITC values showed that the Ca²⁺-binding affinity of the peptide is about 9.914 × 10⁴M⁻¹. Furthermore, the peptide was found to inhibit calcium phosphate precipitation and stabilize amorphous calcium phosphate formation for more than 2 h and finally transform into ordered hydroxyapatite crystals.

Conclusion: Specific concentrations of the amelogenin-based synthetic peptide promoted in vitro remineralization, with higher concentrations exhibiting significantly greater remineralization. This study presented evidence suggesting that the peptide may act as a Ca²⁺carrier as well as a regulating factor. When the stabilizing calcium and phosphorus ions bind with the peptide they become biologically available for the remineralization of deeper carious lesions, while also regulated by the peptide to transform into ordered hydroxyapatite crystals.

Type 2 diabetes as a risk indicator for dental caries in Korean adults: the 2011-2012 Korea national health and nutrition examination survey

OBJECTIVES

The associations between type 2 diabetes (T2D) and untreated dental caries was examined. This study hypothesized that there would be a positive association between T2D and the prevalence of decayed permanent teeth (DT) in representative Korean adults.

METHODS

The information was derived from the Korea National Health and Nutrition Examination Survey conducted in 2011-2012. Sociodemographic and lifestyle variables, anthropometric and biochemical status, metabolic health and glucose tolerance status, oral health behaviors, and dental caries index were evaluated.

RESULTS

The number of DT had a positive association with degree of fasting plasma glucose (FPG) level, and glycated hemoglobin (HbA1c) (p-value = 0.045 and 0.007, respectively). The levels of FPG and HbA1c increased with the number of DT (p for trend = 0.009 and 0.004, respectively). The prevalence of untreated caries uncontrolled T2D participants was about 26% higher than those with normal glucose tolerance levels after adjusting for potential confounders including diets and socioeconomic status (OR [95% CI] = 1.26 [1.02, 1.56]).

CONCLUSIONS

T2D is an independent risk indicator for untreated caries in Korean adults.

In vitro performance of near infrared light transillumination at 780-nm and digital radiography for detection of non-cavitated approximal caries

OBJECTIVES

To evaluate the ability of a Near Infrared Light Transillumination (NILT) device to detect non-cavitated approximal caries lesions; and to compare its performance to Digital Radiography (DR).

METHODS

Thirty human extracted premolars (sound to lesions into the outer one-third of dentin) were selected. Lesion depth was confirmed by micro-computed tomography (μ-CT). Teeth were mounted in a custom-made device to simulate approximal contact. DR and NILT (CariVu™, DEXIS, LLC, Hatfield, PA, USA) examinations were performed and repeated by three trained and calibrated examiners. Sensitivity, specificity, area under ROC curve (A_z), inter- and intra-class correlation coefficients (ICCs) for each method, and correlation among the methods were determined.

RESULTS

ICCs for intra-/inter-examiner agreement were substantial for NILT (0.69/0.64), and moderate for DR (0.52/0.48). Sensitivity/specificity for NILT and DR were 0.68/0.93 and 0.50/0.64, respectively. A_z for NILT was 0.81, while for DR it was 0.61. Spearman correlation coefficient with μ-CT for NILT (0.65, p<0.001) demonstrated moderate association, while that of DR suggested no association (0.19, p=0.289).

CONCLUSION

Within the limitations of this in vitro study, NILT demonstrated a potential for early approximal caries detection. NILT and DR performed the same regarding the accuracy for non-cavitated approximal caries detection; however, NILT was superior to DR in terms of repeatability, agreement and correlation with μ-CT.

CLINICAL SIGNIFICANCE

A commercial version of NILT was recently introduced as a non-irradiative adjunctive caries detection method. It uses near infrared (NIR) light at 780-nm to transilluminate teeth and captures live images from the occlusal surface. This study demonstrates that NILT can be used as an alternative to radiography for non-cavitated approximal caries detection.

Measuring the Remineralization Potential of Different Agents with Quantitative Light-Induced Fluorescence Digital Biluminator

Background

The aim of this study was to investigate the effectiveness of different remineralization agents by quantitative light-induced fluorescence digital Biluminator™ (QLF-D).

Methods

Artificial caries lesions were created, and the teeth were divided according to the tested materials: (i) distilled water, (ii) acidulated phosphate fluoride (APF), (iii) Curodont Repair (CR), (iv) ammonium hexafluorosilicate (SiF) and (v) ammonium hexafluorosilicate plus cetylpyridinium chloride (SiF + CPC). After treatment procedures, each of the samples was placed in artificial saliva. After demineralization and 1 and 4 weeks of remineralization procedures, fluorescence loss and lesion areas were measured with QLF-D. Data were statistically analyzed (α = 0.05).

Results

The fluorescence values of the demineralized enamel specimens treated with the various agents differed significantly compared with pretreatment values for both 1 and 4 weeks (p<0.05). At 4 weeks, the highest fluorescence gain was calculated in the CR, APF and SiF groups compared with the control (p<0.05).

Conclusions

APF, SiF and CR groups yielded greater remineralization ability than SiF + CPC and control groups.

Oriented and Ordered Biomimetic Remineralization of the Surface of Demineralized Dental Enamel Using HAP@ACP Nanoparticles Guided by Glycine

Achieving oriented and ordered remineralization on the surface of demineralized dental enamel, thereby restoring the satisfactory mechanical properties approaching those of sound enamel, is still a challenge for dentists. To mimic the natural biomineralization approach for enamel remineralization, the biological process of enamel development proteins, such as amelogenin, was simulated in this study. In this work, carboxymethyl chitosan (CMC) conjugated with alendronate (ALN) was applied to stabilize amorphous calcium phosphate (ACP) to form CMC/ACP nanoparticles. Sodium hypochlorite (NaClO) functioned as the protease which decompose amelogenin in vivo to degrade the CMC-ALN matrix and generate HAP@ACP core-shell nanoparticles. Finally, when guided by 10 mM glycine (Gly), HAP@ACP nanoparticles can arrange orderly and subsequently transform from an amorphous phase to well-ordered rod-like apatite crystals to achieve oriented and ordered biomimetic remineralization on acid-etched enamel surfaces. This biomimetic remineralization process is achieved through the oriented attachment (OA) of nanoparticles based on non-classical crystallization theory. These results indicate that finding and developing analogues of natural proteins such as amelogenin involved in the biomineralization by natural macromolecular polymers and imitating the process of biomineralization would be an effective strategy for enamel remineralization. Furthermore, this method represents a promising method for the management of early caries in minimal invasive dentistry (MID).

Remineralization ability of sodium fluoride on the microhardness of enamel, dentin, and dentinoenamel junction: An in vitro study

Aim:

Dental tissues such as enamel, dentinoenamel junction (DEJ), dentin, and root dentin can react differently to demineralization and remineralization. The aim of this study was to evaluate the remineralization ability of sodium fluoride on the microhardness of enamel, dentin, and dentinoenamel junction.

Materials and Methods:

Ten extracted third molar teeth were sectioned mesiodistally to form control and test groups. For the test group, initial demineralization was done with acetic acid for 24 h followed by remineralization for 28 days by application of sodium fluoride (226 ppm) for 2 min twice a day. Vickers microhardness test was done to control and test groups at different sites after initial demineralization and on the 3^rd, 5^th, 7^th, 14^th, and 28^th day of remineralization.

Statistical Analysis Used:

Data were analyzed with one-way analysis of variance and post hoc test with a significance level of P < 0.001 with SPSS (21) software.

Results:

Microhardness values in the demineralization group were significantly lower than controls (P < 0.001). Evaluation of remineralization samples showed that microhardness similar to control values were achieved at the 3^rd day in root predentin and on the 5^th day in coronal dentin and coronal predentin. On the 7^th day, remineralization coronal predentin was significantly higher than the control (P < 0.001). On the 14^th day, DEJ axial zone and root dentin were similar to control and coronal dentin was significantly higher than the control (P < 0.001). Enamel was similar to control on the 28^th day. Microhardness of DEJ-cusp tip and DEJ-center of the fissure was significantly lower than control even at the 28^th day (P < 0.001).

Conclusion:

Long-term repeated application of sodium fluoride (226 ppm) can improve the microhardness of demineralized dental tissues on enamel, dentin, and DEJ-axial zone, except in the DEJ-cusp tip and DEJ-center of fissure.

Evaluation of the remineralization capacity of CPP-ACP containing fluoride varnish by different quantitative methods

Objective

The aim of this study was to evaluate the efficacy of CPP-ACP containing fluoride varnish for remineralizing white spot lesions (WSLs) with four different quantitative methods.

Material and Methods

Four windows (3x3 mm) were created on the enamel surfaces of bovine incisor teeth. A control window was covered with nail varnish, and WSLs were created on the other windows (after demineralization, first week and fourth week) in acidified gel system. The test material (MI Varnish) was applied on the demineralized areas, and the treated enamel samples were stored in artificial saliva. At the fourth week, the enamel surfaces were tested by surface microhardness (SMH), quantitative light-induced fluorescence-digital (QLF-D), energy-dispersive spectroscopy (EDS) and laser fluorescence (LF pen). The data were statistically analyzed (α=0.05).

Results

While the LF pen measurements showed significant differences at baseline, after demineralization, and after the one-week remineralization period (p<0.05), the difference between the 1- and 4-week was not significant (p>0.05). With regards to the SMH and QLF-D analyses, statistically significant differences were found among all the phases (p<0.05). After the 1- and 4-week treatment periods, the calcium (Ca) and phosphate (P) concentrations and Ca/P ratio were higher compared to those of the demineralization surfaces (p<0.05).

Conclusion

CPP-ACP containing fluoride varnish provides remineralization of WSLs after a single application and seems suitable for clinical use.

Biomimetic remineralization of demineralized dentine using scaffold of CMC/ACP nanocomplexes in an in vitro tooth model of deep caries

Currently, it is still a tough task for dentists to remineralize dentine in deep caries. The aim of this study was to remineralize demineralized dentine in a tooth model of deep caries using nanocomplexes of carboxymethyl chitosan/amorphous calcium phosphate (CMC/ACP) based on mimicking the stabilizing effect of dentine matrix protein 1 (DMP1) on ACP in the biomineralization of dentine. The experimental results indicate that CMC can stabilize ACP to form nanocomplexes of CMC/ACP, which is able to be processed into scaffolds by lyophilization. In the single-layer collagen model, ACP nanoparticles are released from scaffolds of CMC/ACP nanocomplexes dissolved and then infiltrate into collagen fibrils via the gap zones (40 nm) to accomplish intrafibrillar mineralization of collagen. With this method, the completely demineralized dentine was partially remineralized in the tooth mode. This is a bottom-up remineralizing strategy based on non-classical crystallization theory. Since nanocomplexes of CMC/ACP show a promising effect of remineralization on demineralized dentine via biomimetic strategy, thereby preserving dentinal tissue to the maximum extent possible, it would be a potential indirect pulp capping (IPC) material for the management of deep caries during vital pulp therapy based on the concept of minimally invasive dentistry (MID).

Biomimetic remineralization of demineralized enamel with nano-complexes of phosphorylated chitosan and amorphous calcium phosphate

Remineralization of enamel plays a crucial role in the progression of carious process and the management of early caries lesion. Based on the influence of phosphorylated proteins in biomineralization, the objective of this study was to synthesize nano-complexes of phosphorylated chitosan and amorphous calcium phosphate (Pchi-ACP), and evaluate their ability to remineralize enamel subsurface lesions in vitro. Pchi was synthesized using a previously established chemical method. The biomimetic remineralizing solution containing nano-complexes of Pchi-ACP was prepared by adding CaCl2 and K2HPO4 into Pchi-ACP solution (0.5 % w/v) in sequence. The final concentrations of calcium and phosphate ions were 10 and 6 mM, respectively. The nano-complexes of Pchi-ACP were characterized by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). During testing the enamel lesions were treated with Pchi-ACP and fluoridated remineralizing solutions, respectively. The remineralizing of enamel lesions was examined with field emission electron microscope (FE-SEM) and Micro-CT. ACP was stabilized by Pchi to form nano-complexes that were soluble in water. The size of Pchi-ACP nano-complexes particles was determined to be less than 50 nm. XRD and SAED results confirmed their amorphous phases. FE-SEM and Micro-CT results showed that the remineralizing effect of Pchi-ACP on enamel lesions was similar to that of fluoride. However, the remineralizing rate of Pchi-ACP treatment was significantly higher than that of fluoride treatment (P < 0.05). This study highlighted the potential of nanoparticles functionalized with a natural analogue involved in biomineralization, to remineralize early enamel caries.

Systematic review of noninvasive treatments to arrest dentin non-cavitated caries lesions

AIM: To systematically review the literature on the efficacy of noninvasive methods of arresting the progression of non-cavitated occlusal carious lesions in dentin.

METHODS: The Medline/PubMed, LILACS, SciELO and Scopus databases were searched to identify relevant publications through to November 2013. Only clinical trials evaluating the ability of noninvasive methods to arrest the progression of occlusal non-cavitated carious lesions in dentin were included. Screening, data extraction and quality assessment were conducted independently and in duplicate.

RESULTS: Of 167 citations identified, nine full text articles were screened and five were included in the analysis. All papers reported on occlusal fissure sealing using a self-curing glass ionomer (n = 1) or resin-based (n = 4) sealant. Only the use of resin-based sealant to obliterate occlusal fissures arrested the progression of non-cavitated occlusal carious lesions in dentin.

CONCLUSION: Occlusal fissure sealing with a resin-based sealant may arrest the progression of non-cavitated occlusal dentinal caries. Further clinical trials with longer follow-up times should be performed to increase scientific evidence.

In Vitro Effect of Air-abrasion Operating Parameters on Dynamic Cutting Characteristics of Alumina and Bio-active Glass Powders

Minimally invasive dentistry advocates the maintenance of all repairable tooth structures during operative caries management in combination with remineralization strategies. This study evaluated the effect of air-abrasion operating parameters on its cutting efficiency/pattern using bio-active glass (BAG) powder and alumina powder as a control in order to develop its use as a minimally invasive operative technique. The cutting efficiency/pattern assessment on an enamel analogue, Macor, was preceded by studying the powder flow rate (PFR) of two different commercial intraoral air-abrasion units with differing powder-air admix systems. The parameters tested included air pressure, powder flow rate, nozzle-substrate distance, nozzle angle, shrouding the air stream with a curtain of water, and the chemistry of abrasive powder. The abraded troughs were scanned and analyzed using confocal white light profilometry and MountainsMap surface analysis software. Data were analyzed statistically using one-way and repeated-measures analysis of variance tests (p=0.05). The air-abrasion unit using a vibration mechanism to admix the abrasive powder with the air stream exhibited a constant PFR regardless of the set air pressure. Significant differences in cutting efficiency were observed according to the tested parameters (p&lt;0.05). Alumina powder removed significantly more material than did BAG powder. Using low air pressure and suitable consideration of the effect of air-abrasion parameters on cutting efficiency/patterns can improve the ultraconservative cutting characteristics of BAG air-abrasion, thereby allowing an introduction of this technology for the controlled cleaning/removal of enamel, where it is indicated clinically.

Predictive research methods of enamel and dentine for initial caries detection

Currently, various research methods of enamel and dentine for precautionary diagnostics of initial caries forms are developed; however, the vast majority of these do not provide objective criteria of caries diagnostics or are very difficult to perform. Therefore, the search of diagnostics and enamel research methods, which will allow predicting caries emergence and to carry out personalised prevention of this pathology, is necessary. In this review, modern diagnostic methods that allow understanding the main aspects of caries process, assess the risk of its development, and also suggest the possibility of emergency prevention of caries progression in the nearest future are presented.

Detection of artificial demineralization bordering different types of laminate veneers using visual inspection and storage phosphor radiography

OBJECTIVE

The objective of this study is to compare the diagnostic accuracy of visual inspection (VI) and storage phosphor plate (SPP) radiography for the detection of artificial demineralization bordering different laminate veneers.

MATERIALS AND METHODS

Twenty human maxillary canine teeth were prepared. All-ceramic (A) and hybrid ceramic (H) laminate veneers were fabricated and luted. Veneered teeth were covered except for a circular window on the proximal surface bordering restorations. Teeth were kept in acetic acid buffer to create demineralization and imaged with a SPP system. Ten observers evaluated all teeth first visually then with SPP images for the presence/absence of demineralization. Teeth were examined using scanning electron microscopy (SEM) as well. The accuracy was expressed as the area under the ROC curves (A(z)). Pair-wise comparisons were performed using two-way ANOVA and post hoc t test (p = 0.05). Fleiss kappa (κ) was used for agreement.

RESULTS

SPP radiography was better than the VI for both veneers (p = 0.004). The A(z)s of two veneers were different for both VI (p < 0.005) and SPP (p < 0.005). SEM evaluation revealed lesions confined to enamel. κ was fair for H, and fair to moderate for A. Agreement was higher for the radiographic evaluation for both veneers.

CONCLUSION

Enamel demineralizations bordering hybrid and ceramic laminate veneers can be detected better with SPP radiography than VI and detectability was better for all-ceramic veneers than the hybrid ceramic ones.

CLINICAL RELEVANCE

Early detection of enamel demineralizations bordering laminate veneers would result in time-saving and less-invasive treatment methods; therefore, SPP radiography may be recommended in clinically suspicious cases since it provides better diagnostic accuracy.

Grape seed extract as a potential remineralizing agent: a comparative in vitro study

OBJECTIVE

Remineralization is an effective treatment that may stop or reverse early tooth decay. Grape seed extract (GSE) is the potential remineralizing agent under investigation.

MATERIALS AND METHODS

Sound human tooth sections were obtained from the cervical portion of the root and stored in demineralizing solution at 37°C for 96 hours to induce artificial root caries lesions. The sections were divided into four treatment groups including 6.5% grape seed extract, sodium monofluorophosphate (220 ppm) with 0.05% calcium glycerophosphate, 0.5% calcium glycerophosphate and control (no treatment). An in vitro pH cycling model was used to cycle the demineralized specimens through treatment solutions, acidic buffer and neutral buffer for 8 days at 6 cycles per day. Subsequently, they were evaluated using confocal laser scanning microscope. Data were analyzed using analysis of variance (p < 0.05).

RESULTS

GSE revealed less demineralization and more remineralization compared with other groups.

CONCLUSION

GSE promotes remineralization of artificial root caries lesions.

CLINICAL SIGNIFICANCE

The search for the perfect remineralizing agent continues to this day. GSE could be a welcome addition to the remineralization armamentarium.

Protective effects of salivary factors in dental caries in diabetic patients of Pakistan

Salivary factors have been studied for their effects on the process of dental caries in patients of diabetes mellitus type 2. In this study, protective role of salivary pH, salivary flow rate, and salivary calcium is assessed in the patients of diabetes mellitus type 2 with dental caries. The samples of saliva were collected from 400 patients of diabetes mellitus type 2 and 300 age- and sex- matched controls after getting informed consent. All the subjects were classified into four groups according to age. The severity of dental caries was counted by decayed, missed, and filled teeth (DMFT) score. The salivary pH, flow rate, and calcium levels were found to be low in patients as compared to controls. The levels of fasting blood sugar, HbA1c, and DMFT score were found to be significantly high in patients than controls. The glycemic factors were significantly correlated with salivary factors indicating their influence on progression of caries in diabetes. On the basis of findings, it is concluded that the suitable salivary pH and flow rate may be regarded as main protective factors against dental caries in diabetes. Optimum level of salivary calcium may be responsible for continuous supply of calcium to arrest the demineralization and help reduce the occurrence of dental caries.

Functional remineralization of dentin lesions using polymer-induced liquid-precursor process

It was hypothesized that applying the polymer-induced liquid-precursor (PILP) system to artificial lesions would result in time-dependent functional remineralization of carious dentin lesions that restores the mechanical properties of demineralized dentin matrix. 140 µm deep artificial caries lesions were remineralized via the PILP process for 7–28 days at 37°C to determine temporal remineralization characteristics. Poly-L-aspartic acid (27 KDa) was used as the polymeric process-directing agent and was added to the remineralization solution at a calcium-to-phosphate ratio of 2.14 (mol/mol). Nanomechanical properties of hydrated artificial lesions had a low reduced elastic modulus (E_R = 0.2 GPa) region extending about 70 μm into the lesion, with a sloped region to about 140 μm where values reached normal dentin (18–20 GPa). After 7 days specimens recovered mechanical properties in the sloped region by 51% compared to the artificial lesion. Between 7–14 days, recovery of the outer portion of the lesion continued to a level of about 10 GPa with 74% improvement. 28 days of PILP mineralization resulted in 91% improvement of E_R compared to the artificial lesion. These differences were statistically significant as determined from change-point diagrams. Mineral profiles determined by micro x-ray computed tomography were shallower than those determined by nanoindentation, and showed similar changes over time, but full mineral recovery occurred after 14 days in both the outer and sloped portions of the lesion. Scanning electron microscopy and energy dispersive x-ray analysis showed similar morphologies that were distinct from normal dentin with a clear line of demarcation between the outer and sloped portions of the lesion. Transmission electron microscopy and selected area electron diffraction showed that the starting lesions contained some residual mineral in the outer portions, which exhibited poor crystallinity. During remineralization, intrafibrillar mineral increased and crystallinity improved with intrafibrillar mineral exhibiting the orientation found in normal dentin or bone.

Mechanical and micromorphological evaluation of chlorhexidine-mediated dentin remineralization

Chlorhexidine (CHX) has been reported to reduce self-degradation of collagen fibrils by inhibiting host-derived protease activity in demineralized dentin. Theoretically, if the collagen fibril scaffold of demineralized dentin maintains its original crosslinkage pattern on treatment with CHX and appropriate supplementation with necessary mineral sources, dentin remineralization may occur in demineralized lesions. In this study, we provide direct mechanical and micromorphological evidence for the ability of CHX to promote remineralization of demineralized dentin. Specifically, with respect to demineralized dentin blocks treated with different concentrations of CHX (0.02-2%) and stored in simulated body fluid, we have observed a significant increase in the elastic modulus of dentin treated with relatively high concentrations of CHX (0.2 and 2%) as storage time increased, whereas the elastic modulus of the non-CHX treated control group decreased. We have also observed a dense mineral deposition along collagen fibrils in the dentin group treated with 0.2 and 2% CHX via field emission scanning electron microscopy.

Gum Containing Calcium Fluoride Reinforces Enamel Subsurface Lesions in situ

The aim of this study was to assess the effect of chewing gum containing phosphoryl oligosaccharides of calcium (POs-Ca) and a low concentration of fluoride (F) on the hardness of enamel subsurface lesions, utilizing a double-blind, randomized, and controlled in situ model. Fifteen individuals wore removable lingual appliances with 3 bovine-enamel insets containing subsurface demineralized lesions. Three times a day for 14 days, they chewed one of the 3 chewing gums (placebo, POs-Ca, POs-Ca+F). After the treatment period, cross-sectional mineral content, nanoindentation hardness, and fluoride ion mapping by time-of-flight secondary ion mass spectrometry (TOF-SIMS) were evaluated. Although there were no statistical differences in overall mineral content and hardness recovery rates between POs-Ca and POs-Ca+F subsurface lesions (p > 0.05), nanoindentation at 1-μm distance increments from the surface showed statistical differences in hardness recovery rate between POs-Ca and POs-Ca+F in the superficial 20-μm region (p < 0.05). Fluoride mapping revealed distribution of the ion up to 20 μm from the surface in the POs-Ca+F group. Nanoindentation and TOF-SIMS results highlighted the benefits of bioavailability of fluoride ion on reinforcement of the superficial zone of subsurface lesions in situ (NCT01377493).

In vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste

This study aimed to evaluate the in vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste. One hundred and twenty teeth from 30 volunteers were selected. The teeth were assigned to four treatments: no treatment (negative control); 37% phosphoric acid-etching (PAE) (positive control); PAE + resin-modified glass ionomer cement (RMGIC); and, PAE + composite resin. Patients brushed teeth with fluoridated (n = 15) or non-fluoridated (n = 15) toothpastes, so that etched enamel was protected with screens and it was not in contact with the brush bristles. Remineralization was evaluated by means of laser fluorescence (LF), environmental scanning electronic microscopy, and energy dispersive spectrometry after extraction. The LF means were compared by means of Wilcoxon and Mann Whitney tests. Environmental scanning electron microscopy scores were compared among the groups using a Kruskal Wallis test, whereas the Ca/P ratio was evaluated by means of an Analysis of Variance with subparcels (treatments) and Tukey's post-hoc test. There were no statistically significant differences between the tooth pastes and between the orthodontic adhesives evaluated. Most teeth presented only partial enamel remineralization. Therefore, the fluoride released by the RMGIC was not enough to cause increased crystal regrowth in the acid-etched enamel. The use of fluoridated toothpaste did not provide positive additional effect.

Diagnostic accuracy of proximal enamel subsurface demineralization and its relationship with calcium loss and lesion depth

OBJECTIVE

The aim of this study was to determine the relationship between the amount of calcium loss, lesion depth, and the accuracy of storage phosphor plate (SPP) and film radiographs for the detection of artificial proximal demineralization.

METHODS

Standard enamel windows of extracted premolars were exposed to a demineralizing solution for 60 h, 80 h, 100 h and 120 h. Solutions were analysed for calcium concentration by atomic absorption spectrometer and the lesion depths were calculated by a specific formula. All teeth were radiographed with SPPs and F-speed films before and after acid application. Images were evaluated by five observers. Stereomicroscopic and scanning electron microscopic (SEM) observations were carried out to visualize enamel surfaces after acid exposure. Receiver operating characteristic analysis was used for diagnostic accuracy (A(z)). A(z)s were compared with factorial analysis of variance and t-tests. The relationship between A(z)s and lesion depths was determined with Pearson's correlation test.

RESULTS

Strong positive correlation was found between A(z)s of both radiographic methods and lesion depths. No difference was found between the A(z)s of two radiographic systems for any of the demineralization durations (p > 0.05). Pair-wise comparisons revealed no significant difference in A(z)s of SPPs (p > 0.05), while significant differences were obtained for the A(z)s of films for different demineralization periods (p < 0.05). Stereomicroscopic and SEM observations confirmed demineralizations from superficial to deeper layers of enamel.

CONCLUSION

Subsurface enamel demineralization was not accurately detectable with either storage phosphor plates or F-speed films. The amount of calcium loss and the depth of demineralization have a strong relationship with diagnostic accuracy with a significant effect particularly on F-speed films.

Dental caries in diabetes mellitus: role of salivary flow rate and minerals

This study was designed to evaluate the possible protective role of salivary factors like salivary flow rate and adequate level of calcium, phosphate, and fluoride in diabetes mellitus type 2 patients with dental caries. A total of 398 diabetes mellitus type 2 patients with dental caries and 395 age- and sex-matched non-diabetic subjects with dental caries were included as controls, all of whom gave informed consent. All subjects were divided into four groups according to their age. Decayed, missed, and filled teeth (DMFT) were scored to indicate the severity of dental caries. Saliva was collected, flow rate was noted, and calcium, phosphate, and fluoride were analyzed. The blood glucose, HbA1c, and DMFT indices were found to be significantly high in diabetic patients as compared to controls. The salivary flow rate, calcium, phosphate, and fluoride were found to be significantly low whereas no significant difference was found in salivary magnesium in patients as compared to controls. Optimum salivary flow rate is responsible for establishing protective environment against dental caries. Adequate level of salivary calcium, phosphate, and fluoride is also involved in significant deposition of these minerals in plaque, which greatly reduces the development of caries in the adjacent enamel of teeth.

Activation of bone remodeling after fatigue: differential response to linear microcracks and diffuse damage

Recent experiments point to two predominant forms of fatigue microdamage in bone: linear microcracks (tens to a few hundred microns in length) and "diffuse damage" (patches of diffuse stain uptake in fatigued bone comprised of clusters of sublamellar-sized cracks). The physiological relevance of diffuse damage in activating bone remodeling is not known. In this study microdamage amount and type were varied to assess whether linear or diffuse microdamage has similar effects on the activation of intracortical resorption. Activation of resorption was correlated to the number of linear microcracks (Cr.Dn) in the bone (R(2)=0.60, p<0.01). In contrast, there was no activation of resorption in response to diffuse microdamage alone. Furthermore, there was no significant change in osteocyte viability in response to diffuse microdamage, suggesting that osteocyte apoptosis, which is known to activate remodeling at typical linear microcracks in bone, does not result from sublamellar damage. These findings indicate that inability of diffuse microdamage to activate resorption may be due to lack of a focal injury response. Finally, we found that duration of loading does not affect the remodeling response. In conclusion, our data indicate that osteocytes activate resorption in response to linear microcracks but not diffuse microdamage, perhaps due to lack of a focal injury-induced apoptotic response.

Evaluation of surface structural and mechanical changes following remineralization of dentin

This study sought to gain insights into the surface structural and mechanical changes leading to remineralization of dentin. Remineralization was compared between a continuous remineralization approach and a nonbuffered static approach using solutions of the same initial composition. Artificial carious lesions were treated for 5 days and analyzed every 24 h using nanoindentation in water, SEM, and AFM. The continuous approach yielded a recovery of mechanical properties of up to 60% of normal dentin, whereas the static approach led to recovery of only 10%. Image analysis revealed that the static approach yielded the formation of areas suggestive of an apatite precipitate on the surface of the dentin matrix. In contrast, surface precipitate was absent using the continuous approach, suggesting that mineral formed within the lesion and re-associated with the collagenous matrix. This study provided evidence that mechanical recovery of dentin in near physiological conditions is attainable through the continuous delivery of calcium and phosphate ions.

Comparative Evaluation of the Remineralizing Effects and Surface Micro hardness of Glass Ionomer Cements Containing Bioactive Glass (S53P4):An in vitro Study

Dental cements including the glass ionomer cement (GIC) have found widespread use in restoring tooth structures. In this study, modifications of glass ionomer cements (GICs) were made by adding bioactive glass (BAG) to GIC to obtain bioactive restorative materials. This study used polarized light microscopy (PLM) to examine the remineralization effects of the study materials on dentin. It also evaluated the Vickers microhardness of the experimental materials. Experimental glass ionomer cement (GIC)-BAG materials were made by mixing 10 wt% of BAG particles with conventional cure and resin-modified GIC powders. Class V restorations were made in 80 extracted mandibular teeth which included 4 groups of 20 teeth each. 100 |jm sections of the teeth were examined under polarized light microscope after undergoing pH cycling. Materials were also processed into 80 cylindrical specimens and immersed in water for 7 and 30 days before mechanical tests. Resin-modified GIC containing BAG showed a thick uniform layer of mineralization on the restoration-dentin interface. The conventional cure GIC-based materials had higher surface microhardness than the resin-modified materials.

SIGNIFICANCE

The addition of BAG to GIC compromises the mechanical properties of the materials to some extent. Thus, their clinical use ought to be restricted to applications where their bioactivity can be beneficial, such as root surface fillings and liners in dentistry.

Effect of compounds of Galla chinensis on remineralization of enamel surface in vitro

OBJECTIVE

The aim of the study was to investigate the effect of chemical compounds of Galla chinensis on in vitro the remineralization of enamel surface.

METHOD

Bovine enamel blocks with in vitro produced initial lesions were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4x1 min applications with one of four treatments: Group A: 1000 ppm F aq. (as NaF, positive control); Group B: deionized water (DDW, negative control); Group C: 4000 ppm crude aqueous extract of G. chinensis (GCE); Group D: 4000 ppm gallic acid. The enamel specimens were analysed by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray microdiffraction (XRD).

RESULTS

The morphology of surface enamel was different in each group. The mineral composition was identified as similar to hydroxylapatite, but the crystallite sizes of enamel in different groups were significantly different. In addition, the Ca/P ratios were significantly lower in GCE group.

CONCLUSION

GCE could affect the mineral ions deposit on the surface layer and then modified the remineralization of initial dental caries. The mechanism seems to be different between GCE and gallic acid.