Comparing the remineralization potential of undemineralized dentin powder versus chicken eggshell powder on artificially induced initial enamel carious lesions: an in-vitro investigation.

BACKGROUND: White spot lesions are a widespread undesirable effect, especially prevalent during fixed orthodontic treatments. The study compared the in vitro enamel remineralization potential of undemineralized dentin matrix (UDD) versus chicken eggshell powder (CESP) for artificially induced enamel lesions. METHODS: 100 caries-free and sound maxillary premolars were randomly divided into four groups each contain 25 teeth: Group I (Baseline): No treatment was done to the enamel surface. Group II (Negative control ): The enamel surface of the teeth underwent demineralization using demineralizing solution to create artificial carious lesions then kept in artificial saliva. Group III (CESP treated): After demineralizing the tooth surface, the teeth have been suspended in the CESP remineralizing solution. Group IV (UDD treated): After enamel demineralization, the teeth were suspended in UDD remineralizing solution. The remineralization potential was assessed by Vickers microhardness testing, scanning electron microscopic examination (SEM), and energy dispersive X-ray (EDX). RESULTS: The current study demonstrated an increase in the mean microhardness of CESP and UDD-treated groups; however, It was nearer to the baseline level in the UDD group. SEM imaging revealed greater enamel remineralization in the UDD group compared to the remaining groups. The UDD group disclosed complete coverage for the prismatic enamel compared to the CESP group, which revealed a partially remineralized enamel surface. Interestingly, the Ca/P ratio increased significantly in the CESP group compared to the negative control group. In contrast, a higher significant increase in the mean Ca/P ratios was recorded in the UDD group compared to the test groups. CONCLUSION: biomimetic UDD and CESP powder should be utilized to treat enamel early carious lesions. However, UDD demonstrated the most significant remineralization potential.

Onset and progression of dental erosion in a mouse model.

OBJECTIVE: Purpose of this research was to examine the onset, progression and wear rates of dental erosion in an established mouse model. MATERIAL AND METHODS: Dental erosion in mice was experimentally induced, and the acidic effects of cola drink on their teeth after 2, 4 and 6-weeks were closely analysed by scanning electron microscopy. The tooth height and enamel or dentin loss were established.  Results: The dental erosion on the molars showed clear progression from 2 to 6 weeks. By the 2-week mark, a significant portion of enamel was already eroded, revealing the dentin on the lingual cusps. When adjusted for attritional wear, molars exposed to cola for 2 weeks showed a 35% drop in lingual tooth height compared to controls (533 µm vs. 818 µm). At 4 and 6 weeks, the cola-exposed group continued to display decreased lingual tooth heights by 40% (476 µm vs. 799 µm) and 43% (440 µm vs. 767 µm), respectively. CONCLUSION: This study revealed significant acidic effects of cola drink on mouse molars as early as 2 weeks. These findings highlight the challenge of monitoring dental erosion clinically and underscore the importance of early preventive and intervention measures.

Do the methods for cleaning the base of brackets used in indirect bonding interfere with adhesion to tooth enamel?

OBJECTIVE: The objective of this study was to evaluate the shear bond strength of metal brackets bonded with indirect bonding, under different surface treatment protocols. MATERIAL AND METHODS: 40 bovine teeth were randomly divided into four groups (n = 10), according to the type of surface treatment: G1 = 70% alcohol, G2 = air/water spray, G3 = 100-µm aluminum oxide blasting, G4 = direct boning. After drying, the standard Edgewise central incisor brackets were bonded with light-cured resin. The brackets were moved from the plaster models by means of a transfer tray made with condensation silicone, and bonded to the surface of the enamel with self-curing adhesive. The samples were submitted to shear tests by a universal test machine. Data were analyzed with SPSS 20.0 by the one-way ANOVA test and the Tukey post-test. RESULTS: No statistically significant difference (p=0.174) was observed between the mean forces measured between the group for shear strength values of the groups during the test: G1 (5.33 MPa), G2 (3.52 MPa) and G3 (4.58 MPa). CONCLUSION: The bracket surface treatment protocols presented similarities in shear bond strength test. However, alcohol 70% and oxide blasting presented higher absolute values of resistance than the water group.

Enhanced tooth bleaching with a hydrogen peroxide/titanium dioxide gel.

BACKGROUND: This study aimed to explore the effects of the titanium dioxide (TiO2) concentration and particle size in hydrogen peroxide (HP) on tooth bleaching effectiveness and enamel surface properties. METHODS: TiO2 at different concentrations and particle sizes was incorporated into 40% HP gel to form an HP/TiO2 gel. The specimens were randomly divided into 8 groups: C1P20: HP + 1% TiO2 (20 nm); C3P20: HP + 3% TiO2 (20 nm); C5P20: HP + 5% TiO2 (20 nm); C1P100: HP + 1% TiO2 (100 nm); C3P100: HP + 3% TiO2 (100 nm); C5P100: HP + 5% TiO2 (100 nm); C0: HP with LED; and C0-woL: HP without LED. Bleaching was conducted over 2 sessions, each lasting 40 min with a 7-day interval. The color differences (ΔE00), whiteness index for dentistry (WID), surface microhardness, roughness, microstructure, and composition were assessed. RESULTS: The concentration and particle size of TiO2 significantly affected ΔE00 and ΔWID values, with the C1P100 group showing the greatest ΔE00 values and C1P100, C3P100, and C5P100 groups showing the greatest ΔWID values (p < 0.05). No significant changes were observed in surface microhardness, roughness, microstructure or composition (p > 0.05). CONCLUSIONS: Incorporating 1% TiO2 with a particle size of 100 nm into HP constitutes an effective bleaching strategy to achieve desirable outcomes.

New Generation of Orthodontic Elastomeric Ligature to Prevent Enamel Demineralization In Vivo.

This study aimed to synthesize a novel elastomeric ligature with dimethylaminohexadecyl methacrylate (DMAHDM) grafted, providing a new strategy for improving the issue of enamel demineralization during fixed orthodontics. DMAHDM was incorporated into elastomeric ligatures at different mass fractions using ultraviolet photochemical grafting. The antibacterial properties were evaluated and the optimal DMAHDM amount was determined based on cytotoxicity assays. Moreover, tests were conducted to evaluate the in vivo changes in the mechanical properties of the elastomeric ligatures. To assess the actual in vivo effectiveness in preventing enamel demineralization, a rat demineralization model was established, with analyses focusing on changes in surface microstructure, elemental composition, and nanomechanical properties. Elastomeric ligatures with 2% DMAHDM showed excellent biocompatibility and the best antibacterial properties, reducing lactic acid production by 65.3% and biofilm bacteria by 50.0% within 24 h, without significant mechanical property differences from the control group (p > 0.05). Most importantly, they effectively prevented enamel demineralization in vivo, enhancing elastic modulus by 73.2% and hardness by 204.8%. Elastomeric ligatures incorporating DMAHDM have shown great potential for application in preventing enamel demineralization, providing a new strategy to solve this issue during fixed orthodontics.

Evaluating the Effects of Cigarette Smoking and Heated Tobacco Products on Hard Dental Tissues: A Comparative Histological and Colorimetric Analysis.

OBJECTIVES: This study aimed to evaluate and compare the impact of cigarette smoking (CS) and heated tobacco (HT) on the alteration of color and ultrastructural characteristics of human enamel and cementum. BACKGROUND: According to tobacco companies, a less harmful substitute for CS is HT products. Nevertheless, comprehensive research on the effects of HT on tooth structures has been lacking. This study aimed to evaluate and compare the impact of CS and HT on the alteration of color and ultrastructural characteristics of human enamel and cementum. MATERIALS AND METHODS: Thirty intact and noncarious human maxillary premolars extracted for orthodontic treatment purposes, previously disinfected, were used in the study. The specimens were randomly separated into six groups (n = 10), as follows: Group 1: enamel without smoking exposure; Group 2: enamel exposed to CS; Group 3: enamel exposed to HT; Group 4: cementum without smoking exposure; Group 5: cementum exposed to CS; and Group 6: cementum exposed to HT. The measurement of color change was conducted using a spectrophotometer. The surface alterations and mineral composition of enamel and cementum were evaluated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. ANOVA test followed by Tukey's post hoc test was used to determine significant differences between groups. RESULTS: Results showed that CS had a more pronounced effect on enamel and cementum color changes than HT. The impact of CS and HT on color changes was more evident in cementum than in enamel. Surface morphology of enamel and cementum showed alterations in histology following exposure to both smoking types. Moreover, the mineral content experienced a significant reduction after using CS and HT. The reduction in calcium content after CS and HT exposure was similar. However, HT led to a significant decrease in the phosphorus content of enamel when compared with CS. At the same time, CS exposure in cementum resulted in a more significant reduction in Ca/P ratio than HT. CONCLUSIONS: Although HT may appear to present a lower danger to hard dental tissues than CS, it is not entirely harmless. CS results in more color changes on the enamel and cementum of teeth. Both smoking methods affected the mineral content of teeth, with CS having a significant effect on the roots, while HT significantly affected the crowns' mineral composition.

Remineralizing effect of NSF on artificial enamel caries.

INTRODUCTION: Nanotechnology offers new approaches and endless opportunities for remineralizing tooth decay without being toxic or causing allergies. This study aimed to determine the effect of nanosilver fluoride (NSF) on the remineralization potential of enamel caries-like lesions compared to 5% sodium fluoride varnish in permanent teeth. METHODS: Fifteen teeth (molars and premolars) were gathered, cleaned, and polished using a scaler. After sectioning the teeth mesiodistally and removing the roots, the thirty specimens were subjected to a demineralized solution to induce early enamel lesions and then assigned randomly into two equal groups. The test materials were applied, and then all the specimens were subjected to a pH cycling model for 30 days. DIAGNOdent and surface roughness were investigated, and an evaluation of the enamel Ca and P weight% for Ca/P ratio calculation was done using SEM-EDX to analyze the specimens at the end of the study. The data were analyzed using an independent t-test. RESULTS: The mean values for the DIAGNOdent measurements for NSF and NaF at baseline and after demineralization were not significantly different (p > 0.05). After treatment, NaF varnish showed a significantly higher mean DIAGNOdent measurement (11.8 ± 5.80) than NSF (4.7 ± 1.6). The mean surface roughness of the NaF group (1.64 ± 0.39) was much higher than NSF's mean surface roughness (1.07 ± 0.21). Specimens treated with NSF had statistically significant smoother surfaces (p < 0.001). The NSF group had a higher mean Ca/P ratio (2.9 ± 0.35) than NaF (2.2 ± 0.11). This difference was statistically significant (p = 0.012). CONCLUSION: The study reveals that nano silver fluoride is a more effective treatment than sodium fluoride varnish in enhancing teeth's clinical characteristics, particularly in terms of mineral content and surface roughness, suggesting it could be an improved strategy to prevent dental caries and maintain enamel integrity.

Effect of hydrogen peroxide versus charcoal-based whitening mouthwashes on color, surface roughness, and color stability of enamel.

BACKGROUND: Patients tend to favor the whitening mouthwashes as they are easily applied and affordable. This study aimed to evaluate the effect of hydrogen peroxide versus charcoal-based whitening mouthwashes on color, surface roughness, and color stability of enamel. In the current study, the whitening mouthwashes used have the ability to stop future stains due to their white seal technology. METHODS: A total of 21 permanent central incisor teeth extracted for periodontal reasons were used in the present study. Teeth roots were sectioned and crowns were mounted in self-cured acrylic resin blocks. The specimens were randomly divided into three groups (n = 7) according to the tested whitening mouthwash: Control group ? DW" (Distilled water), ?OW" group: Peroxide-based mouthwash (Colgate Optic White) and ?CP" group: Charcoal-based mouthwash (Colgate® Plax Charcoal). Regarding ?OW" and ?CP" groups, the specimens were immersed in 20 ml of the tested mouthwash in each corresponding group for 1 min twice daily (morning and evening) for a total of 12 uninterrupted weeks. Color change was assessed using VITA Easyshade spectrophotometer and surface roughness (Ra) was measured using a white light interferometer. The specimens were stained using black tea solution and color was measured after 24 h of immersion for assessment of color stability. RESULTS: Color change results revealed that both whitening mouthwashes were able to restore color comparable to the control group with no significant difference between them. Regarding surface roughness, the control group showed the highest mean Ra value, followed by ?OW" group while ?CP" group showed the lowest mean Ra value. While color stability after staining, the control group showed a significantly higher value than the ?CP" and ?OW" groups. CONCLUSION: Hydrogen peroxide and charcoal-based whitening mouthwashes improve the color of enamel with no adverse effect on the surface roughness. Both whitening mouthwashes were beneficial to maintain the color after staining and prevent future enamel stains.

Influence of coffee characteristics on tooth discoloration.

PURPOSE: To evaluate the impact of coffee attributes on tooth discoloration, emphasizing the importance of potential factors such as serving temperature, bean variety, and chlorogenic acid (CGA) content. METHODS: Coffee preparation involved the extraction of espresso from four types of roasted beans (Vietnam Robusta, Uganda Robusta, Ethiopia Yirgacheffe Arabica, and Colombia Supremo Arabica), followed by chlorogenic content analysis using high-performance liquid chromatography. Bovine tooth enamel specimens were carefully prepared and stained with coffee (hot and iced), with a color assessment conducted at different time intervals (3, 9, 24, 48, and 72 hours). The Vickers hardness tester was employed to ensure specimen quality, while spectrophotometry aided in color analysis using the CIEDE2000 formula. RESULTS: The results revealed varying effects of serving temperature, bean type, and CGA content on tooth discoloration. It was demonstrated that perceptible color differences occur after a 3-hour immersion in coffee, with hot coffee showing higher staining potential compared to iced variations. Furthermore, chlorogenic acid content and bean type significantly affected tooth discoloration, with higher chlorogenic acid levels associated with increased staining. Notably, Robusta coffee showed less discoloration compared to Arabica, potentially due to differences in pH levels. CLINICAL SIGNIFICANCE: The findings provide valuable insights for both dental practitioners and coffee consumers, assisting in making informed decisions regarding coffee intake and oral hygiene.

Effects of graphene oxide and graphene quantum dots on enhancing CPP-ACP anti-caries ability of enamel lesion in a biofilm-challenged environment.

OBJECTIVE: To investigate the anticaries effects of graphene oxide (GO) and graphene quantum dots (GQDs) combined with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on enamel in a biofilm-challenged environment. MATERIAL AND METHODS: GO and GQDs were synthesised using citric acid. The antibiofilm and biofilm inhibition effects for Streptococcus mutans were evaluated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and colony-forming units (CFU). Remineralisation ability was determined by assessing mineral loss, calcium-to-phosphorus ratio, and surface morphology. To create a biofilm-challenged environment, enamel blocks were immersed in S. mutans to create the lesion and then subjected to artificial saliva/biofilm cycling for 7 days. Anticaries effects of GO, GQDs, GQDs@CPP-ACP, GO@CPP-ACP, and CPP-ACP were determined by broth pH and mineral changes after 7-day pH cycling. Biocompatibility was tested using a Cell Counting Kit-8 (CCK8) assay for human gingival fibroblasts (HGF-1). RESULTS: GQDs and GO presented significant antibiofilm and biofilm inhibition effects compared to the CPP-ACP and control groups (P < 0.05). The enamel covered by GQDs and GO showed better crystal structure formation and less mineral loss (P < 0.05) than that covered by CPP-ACP alone. After 7 days in the biofilm-challenged environment, the GO@CPP-ACP group showed less lesion depth than the CPP-ACP and control groups (P < 0.05). GO and GQDs showed good biocompatibility compared to the control group by CCK8 (P > 0.05) within 3 days. CONCLUSION: GO and GQDs could improve the anti-caries effects of CPP-ACP, and CPP-ACP agents with GO or GQDs could be a potential option for enamel lesion management. CLINICAL SIGNIFICANCE: GO and GQDs have demonstrated the potential to significantly enhance the anticaries effects of CPP-ACP. Incorporating these nanomaterials into CPP-ACP formulations could provide innovative and effective options for the management of enamel lesions, offering improved preventive and therapeutic strategies in dental care.

EFFECT OF LASER IRRADIATION ASSOCIATED WITH FLUORIDE IN DECREASING EROSIVE TOOTH WEAR: A SYSTEMATIC REVIEW WITH A NETWORK META-ANALYSIS  .

OBJECTIVE: The present systematic review with a network meta-analysis (NMA) aimed to evaluate the effect of high-power lasers, associated or not with fluoride compounds, to control and prevent Erosive Tooth Wear (ETW). METHODS: The review was registered in the PROSPERO (CRD42021242547) and followed the PICO question: P (population): enamel and dentin substrate; I (Intervention): high-power laser irradiation, associated or not with fluoride compounds; C (Control): no-treatment; and O (Outcomes): prevention/control of ETW. The electronic databases PubMed, Scopus, and EMBASE were searched. Two independent reviewers evaluated in vitro and in situ studies. The risk of bias was assessed using the RoBDEMAT tool. The estimated treatment effect derived from direct and indirect comparisons were analyzed and the difference between these effects was calculated based on the data of enamel and dentin surface loss (in µm). RESULTS: A total of 179 studies were retrieved and after the exclusion of duplicates, 103 studies had their titles and abstracts evaluated. Thirty-nine studies had their full text analyzed for data extraction (Cohen Kappa = 0.88). For sound enamel, the laser irradiation (L), fluoride application (F) and, the association of treatments (L + F) promoted higher protection than No-Treatment (NT). For eroded enamel, L + F and F did not differ, but both treatments reduced surface loss compared to NT and L. For sound and eroded dentin, treatments with laser increased surface loss. CONCLUSIONS: Although a high-power laser has some potential to prevent erosive tooth wear, this effect is not better than that of standard fluoride. The use of laser in the management of dentin erosive wear can be harmful.

Comparison of various methods of restoring adhesion to recently bleached enamel.

AIM: This study compared the effectiveness of several techniques in restoring compromised bonding to recently bleached enamel. METHODS: Seventy-five healthy bovine incisors were divided into five groups (n = 15). Fifteen teeth (Group 1) remained intact, whereas 60 (Groups 2 to 5) underwent at-home bleaching with 16% carbamide peroxide. The bonding procedures were as follows: Group 1: Bonding of resin composite to unbleached enamel; Group 2: Bonding immediately after bleaching; Group 3: Application of a 10% sodium ascorbate solution for 10 min before bonding; Group 4: Enamel removal to the depth of 0.5 mm; and Group 5: Increased curing time of the bonding agent to 80 instead of 20 s. After 24 h, the specimens were subjected to micro-shear testing, and the failure mode was determined. RESULTS: ANOVA revealed a significant difference in bond strength among the groups (P < 0.001). The mean bond strength was significantly lower in group 2 than in other groups (P < 0.05), which showed comparable bond strength to each other (P > 0.05). Adhesive failure was the most predominant failure type in all groups. The mixed failure occurred with a frequency of 26.7% in groups 3 and 5. The Fisher's exact test revealed a significant difference in failure modes among the groups (P = 0.047). CONCLUSIONS: The three experimental procedures used in this study, including the application of 10% sodium ascorbate before bonding, enamel removal to the depth of 0.5 mm, and increasing the curing time of the bonding agent to 80 s, were effective in restoring the compromised bonding to recently bleached enamel.

Influence of using different toothpaste during bleaching with violet LED light (405 nm) on the colour and roughness of dental enamel: an in vitro study.

This in vitro study aimed to investigate potential changes in the color and roughness of dental enamel resulting from the use of different toothpaste formulations during bleaching with violet LED light (405 nm). Sixty specimens of bovine incisors, each measuring 6 × 6 × 3 mm, were segregated into six distinct experimental groups based on their respective treatments (n = 10): C + VL: Brushing with Colgate® Total 12 + bleaching with violet LED; LB + VL: Brushing with Colgate® Luminous White Brilliant + bleaching with violet LED; LI + VL: Brushing with Colgate® Luminous White Instant + violet LED bleaching; C: Brushing with Colgate® Total 12; LB: Brushing with Colgate® Luminous White Brilliant; LI: Brushing with Colgate® Luminous White Instant. The examined variables included alterations in color (∆L*, ∆a*, ∆b*, ∆Eab, and ∆E00), surface roughness (Ra), and scanning electron microscopy observations. No statistically significant distinctions emerged in total color variations (∆E00 and ∆E) among the groups under scrutiny. Notably, the groups that employed Colgate® Luminous White Instant displayed elevated roughness values, irrespective of their association with violet LED, as corroborated by scanning electron microscopy examinations. It can be concluded that whitening toothpastes associated to violet LED do not influence the color change of dental enamel in fifteen days of treatment. Toothpastes with a higher number of abrasive particles showed greater changes in enamel roughness, regardless of the use of violet LED.

Evaluation of the effect of self-assembling peptide and fluoride varnish, alone or in combination with laser irradiation, on artificial enamel caries: a SEM/EDS and Micro-CT study.

OBJECTIVE: The aim of this study was to investigate the effect of remineralization agents such as fluoride varnish and P11-4, alone and in combination with Er: YAG laser, on in-vitro hard tissue repair in artificial enamel lesions. MATERIALS AND METHODS: A total of sixty enamel surfaces of 4 × 5 mm in size were created on both the buccal and lingual sides of thirty extracted wisdom teeth. Remineralization agents were applied to the specimens that were grouped as follows: Group 1, control; Group 2, fluoride varnish (FV); Group 3, P11-4; Group 4, laser; Group 5, laser + FV; and Group 6, laser + P11-4. The fluorescence level was determined with DiagnoDent. The enamel mineral density, area and volume, and caries lesion area and volume were determined with micro-computed tomography (µCT), surface features were evaluated using scanning electron microscopy (SEM), and elemental analysis was performed using energy dispersive x-ray spectroscopy (EDS) . RESULTS: For specimens treated only with self-assembling peptide P11-4, the caries lesion area (mm2) values were 38.19 and 21.62, and the caries lesion volume (mm3) values were 6.27 and 2.99, respectively for pre- and post-treatment. In combination usage of self-assembling peptide P11-4 and laser, the caries lesion area (mm2) values were 38.39 and 16.91, and the caries lesion volume (mm3) values were 11.15 and 3.64, respectively for pre- and post-treatment. In the application of the P11-4 alone and in combination with laser, there was a statistically significant decrease in DiagnoDent values, an increase in enamel volume(mm3),enamel area(mm2) and mineral density(g/cm3) values and a decrease in caries lesion volume(mm3) and area(mm2) obtained by µCT, and an increase in %Ca and %F values obtained by SEM/EDS analysis (p < 0.05). It was discovered that the samples treated with P11-4 had a considerably higher rise in the Ca/P ratio than the samples treated with FV (p < 0.05). The calcium content increased significantly more when P11-4 application was combined with laser irradiation (p < 0.05). CONCLUSIONS: The combined use of self-assembling peptide P11-4 and laser accelerated the remineralization process and increased the remineralization capacity. CLINICAL RELEVANCE: FV and P11-4, alone or in combination with laser, can be successfully used as remineralization agents in initial enamel caries.

The use of silver diamine fluoride to prevent/treat enamel carious lesions: a narrative review.

This comprehensive literature review examines the use of silver diamine fluoride (SDF) for the prevention and treatment of enamel carious lesions. SDF has been approved by different international drug associations as a caries-preventing agent to be used on deep carious lesions (dentin). However, SDF can cause staining of exposed tooth structures. Furthermore, the effect of SDF on the bond of adhesives to the tooth structure is still being determined. This review explores various studies on the use of SDF to treat enamel carious lesions, highlighting its effectiveness and preventive action. The literature suggests that SDF inhibits bacterial growth, promotes remineralization, and does not negatively affect adhesive retentions. Potassium iodide (KI) or glutathione (GSH) can reduce staining and discoloration. However, the reviewed studies have limitations. Further research, including well-designed clinical trials, is necessary to validate the findings and evaluate the long-term implications of SDF treatment. Conclusion: Despite the above-mentioned limitations, SDF shows potential as a therapy for enamel caries prevention, remineralization, and use as an adjuvant to other dental treatments, warranting further investigation and the refinement of application methods.

Silver diamine fluoride in preventing enamel erosion: An in vitro study with salivary pellicle.

OBJECTIVES: To compare the prevention of enamel erosion and discolouring effect with a single and two weekly topical applications of silver diamine fluoride (SDF) solution. METHODS: Human enamel blocks were divided into four groups. Group 1 (SDF2) received two weekly applications of SDF solution (Advantage Arrest: 260,000 ppm Ag, 44,300 ppm F, pH 9.1). Group 2 (SDF1) received a single application of SDF solution. Group 3 (SNF, Positive Control) received daily application of stannous-chloride/amine-fluoride/sodium-fluoride solution (Elmex® Enamel professional: 800 ppm Sn(II), 500 ppm F, pH 4.5). Group 4 (DW, Negative Control) received daily application of deionised water. The treated blocks were subjected to a 14-day erosive challenge. Crystal characteristics, elemental composition, surface morphology, percentage of surface microhardness loss (%SMHL), surface loss, and total colour change (ΔE) of the blocks were investigated using X-ray diffraction (XRD), energy-dispersive spectrometry (EDS) and scanning electron microscopy (SEM), Vickers' hardness testing, non-contact profilometry, and digital spectrophotometry, respectively. RESULTS: XRD and EDS revealed precipitates of silver for SDF2 and SDF1 and tin for SNF. SEM showed prominent etched enamel pattern on DW than the other three groups. The%SMHL (%) of SDF2, SDF1, SNF, and DW were 26.6 ± 2.9, 33.6 ± 2.8, 38.9 ± 2.9, and 50.5 ± 2.8 (SDF2SDF1=SNF>DW, p < 0.05). CONCLUSION: Two weekly applications was more effective than a single application of SDF in preventing enamel erosion, though it caused more discolouration. CLINICAL SIGNIFICANCE: Topical application of 38 % SDF with two weekly applications protocol is effective in preventing enamel erosion.

Masking efficacy of bleaching and/ or resin infiltration of fluorotic spots on anterior teeth - a systematic review and meta-analysis.

OBJECTIVES: The aim of this systematic review and meta-analysis was to evaluate the masking success of bleaching and/or resin infiltration treatment of fluorotic lesions in anterior teeth of adults and adolescents. DATA SOURCES: PubMed, Cochrane Library, and Embase were systematically searched from the beginning of documentation to December 31, 2023. PRIMARY OUTCOME WAS THE NUMBER OF MASKED TEETH: A tooth was considered masked when the color difference (ΔE CIE76) between fluorotic areas and the surrounding sound enamel was ≤3.7 and unmasked if ΔE > 3.7. Secondary outcomes were mean ΔE values between fluorotic and sound enamel reported for a treatment group at baseline and after any intervention as well as patient satisfaction. STUDY SELECTION: Of 1575 search results 4 publications met the inclusion criteria, comprising 230 treated anterior teeth with fluorosis in 47 patients. Meta-analyses were performed comparing the result after treatment (bleaching, resin infiltration, or bleaching followed by resin infiltration) to baseline. RESULTS: Bleaching and resin infiltration were suitable intervention strategies to improve the esthetics of fluorosis affected anterior teeth, with a combination of both treatment approaches being particularly effective in reducing the color difference between fluorotic defects and the surrounding sound enamel below the acceptability thresholds of 3.7 (success rate [95 %CI]: 0.75 [0.44, 1.06]). Patient satisfaction increased after treatments, indicating a beneficial impact on their mental health. The overall bias of the included studies was 2.5 (ROBINS-I analysis tool). CONCLUSION: There is evidence that resin infiltration with preceding bleaching therapy is more effective in masking fluorotic lesions in anterior teeth than bleaching alone. The combination therapy also showed a tendency towards higher success rates compared to infiltration alone. However, this difference was statistically not significant, and more studies are needed to further assess the efficacy of specific treatments and their combinations as well as the certainty in the evidence. The methodologic heterogeneity of study designs regarding estimation of color difference before and after treatment and bleaching protocols calls for unification in future studies. CLINICAL SIGNIFICANCE: Results of this systematic review and meta-analysis revealed the combination of bleaching followed by resin infiltration as efficacious approach for masking fluorotic lesions in young adults. While resin infiltration alone improves the aesthetic appearance of fluorotic lesions, dentists should consider a combined bleaching-infiltration regimen to achieve more favorable clinical outcome for their patients.

Surface porosity of enamel white spot lesions and penetration of fluorapatite nanocrystals into their subsurface: proof-of-concept study.

OBJECTIVES: In this study, we used atomic force microscopy (AFM) to quantify the size of surface pore apertures of enamel white spot lesions and then demonstrated the penetration of fluorapatite nanocrystals (nFA) into the subsurface of these lesions. METHODS: For the porosity study, enamel lesions were created on three sound human teeth using a demineralizing gel for 8 days. The interface between sound enamel and the artificial lesion was analyzed by AFM. To visualize the penetration of nFA tagged with a calcium-binding fluorophore (Fluo-4) into the subsurface of white spot lesions, we used two-photon microscopy. Sixteen extracted human teeth with either active, natural, or in vitro-created carious lesions in enamel were randomly divided into three groups. The teeth were treated for 2 min with either a suspension of tagged nFA crystals, Fluo-4 alone, or deionized water, and left for 30 min before being washed with distilled water and examined microscopically. RESULTS: A greater concentration of surface pores with larger areas was observed on the in vitro demineralized enamel (29 % of pores greater than 1.0 µm2) when compared with the adjacent sound enamel (8 % of pores greater than 1.0 µm2) (p=0.012, Fisher exact test). In vitro and natural lesions treated with tagged nFA showed fluorescence at depths ranging from 50 to 170 µm, demonstrating penetration of the nFA into the lesion subsurface. The lesions treated with Fluo-4 alone with no crystals showed mostly surface fluorescence (restricted to the outer 25 µm), while those treated with deionized water showed minimal (restricted to the outer 20 µm) to no fluorescence. CONCLUSION: We have demonstrated the use of AFM to quantify the surface pore apertures and two-photon microscopy to visualize nFA crystals in the subsurface of non-cavitated enamel lesions. CLINICAL SIGNIFICANCE: The restoration of the subsurface of non-cavitated caries lesions is a clinical challenge. This study demonstrated that a 2 min application of nFA could penetrate through the surface apertures of non-cavitated enamel lesions into their subsurface.

Synthesis and characterization of different nano-hydroxyapatites and their impact on dental enamel following topical application for dental bleaching.

OBJECTIVE: This study aims to synthesize, characterize, and assess the penetration of hydrogen peroxide (HP), color change (CC), and surface morphology changes after the application of two distinct nano-hydroxyapatite (nano-HAp). METHODS: Two nano-HAp were previously synthesized by co-precipitation: one with rod-shaped particles (RS) and the other with spherical-shaped particles (SS). The surface charge of the nano-HAp particles was determined at varying pH levels and characterized by X-ray diffraction patterns and Fourier transform infrared spectroscopy. The morphology of the samples was assessed using scanning electron microscopy (SEM). The nano-HAp particles were applied before the dental bleaching procedure. Forty teeth were divided into four groups (n = 10) according to the bleaching treatment: no treatment, bleaching with 35 % HP only, RS application and bleaching with 35 % HP, and SS application and bleaching with 35 % HP. HP concentration (µg mL-1) was measured using UV-Vis, while CC was evaluated with a digital spectrophotometer (ΔEab, ΔE00 and WID). Additionally, four teeth from each group were selected for SEM analysis. Statistical analysis encompassed one-way ANOVA, Tukey's, and Dunnet's tests. RESULTS: RS and SS were successfully synthesized by coprecipitation, primarily differing in pH during synthesis. Both variations of nano-HAp morphology significantly reduced HP diffusion into the pulp chamber (p < 0.001). Regarding enamel morphology, groups analyzed post dental bleaching exhibited greater HAp deposition on the enamel surface. Notably, this deposition did not impede CC. SIGNIFICANCE: The utilization of different nano-HAp morphologies prior to dental bleaching appears to be a promising strategy for mitigating adverse effects associated with dental bleaching procedures.

Preventing proximal enamel caries in neighboring tooth with glass ionomer cement restoration and silver diamine fluoride pretreatment.

OBJECTIVE: To investigate caries preventive effects of 38 % silver diamine fluoride (SDF) pretreatment on neighboring tooth proximal to glass ionomer cement (GIC), including conventional GIC (CGIC) and resin-modified GIC (RMGIC) restorations in an in vitro model. METHODS: HUMAN TOOTH BLOCKS WERE RESTORED WITH: SDF+CGIC (Group 1), CGIC (Group 2), SDF+RMGIC (Group 3) or RMGIC (Group 4). Enamel specimen simulating proximal surface of neighboring tooth was placed in proximity to the restorations. The specimen underwent cariogenic challenge with cross-kingdom biofilm of Streptococcus mutans, Lacticaseibacillus casei and Candida albicans. After cariogenic challenge, the biofilm's growth kinetics, viability, and morphology were evaluated by propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), respectively. The enamel lesion depth, surface morphology and crystal characteristics were determined by micro-computed tomography (micro-CT), SEM and X-ray diffraction (XRD), respectively. RESULTS: PMA-qPCR demonstrated lower microbial growth in Group 1 and 3 compared with Group 2 and 4 (p < 0.05). CLSM showed the dead-to-live ratio in Groups 1-4 were 1.15±0.12, 0.53±0.13, 1.10±0.24 and 0.63±0.10, respectively (Group 1,3 > 2,4, p < 0.05). SEM revealed Groups 1 and 3 had scattered biofilm whereas Group 2 and 4 had confluent biofilm. Micro-CT showed the enamel lesion depths (µm) were 98±9, 126±7, 103±6 and 128±7 for Group 1 to 4, respectively (Group 1,3 < 2,4, p < 0.05). SEM revealed oriented and ordered enamel prismatic patterns in Group 1 and 3, not in Group 2 and 4. XRD showed the reflections of hydroxyapatite in Groups 1 and 3 were sharper than Groups 2 and 4. CONCLUSION: SDF pretreatment enhances the preventive effect of GIC on proximal enamel surface on neighboring tooth through inhibiting cariogenic biofilm, reducing enamel demineralization and promoting enamel remineralization. CLINICAL SIGNIFICANCE: SDF pretreatment of GIC restorations can help prevent caries on neighboring teeth, particular for patients with high caries risk.