Acquired enamel pellicle and biofilm engineering with a combination of acid-resistant proteins (CaneCPI-5, StN15, and Hemoglobin) for enhanced protection against dental caries - in vivo and in vitro investigations.

OBJECTIVE: This study was designed in two-legs. In the in vivo, we explored the potential of a rinse solution containing a combination (Comb) of 0.1 mg/mL CaneCPI-5 (sugarcane-derive cystatin), 1.88 × 10- 5M StN15 (statherin-derived peptide) and 1.0 mg/mL hemoglobin (Hb) to change the protein profile of the acquired enamel pellicle(AEP) and the microbiome of the enamel biofilm. The in vitro, was designed to reveal the effects of Comb on the viability and bacterial composition of the microcosm biofilm, as well as on enamel demineralization. MATERIALS AND METHODS: In vivo study, 10 participants rinsed (10mL,1 min) with either deionized water (H2O-control) or Comb. AEP and biofilm were collected after 2 and 3 h, respectively, after rinsing. AEP samples underwent proteomics analysis, while biofilm microbiome was assessed via 16 S-rRNA Next Generation Sequencing(NGS). In vitro study, a microcosm biofilm protocol was employed. Ninety-six enamel specimens were treated with: 1)Phosphate-Buffered Solution-PBS(negative-control), 2)0.12%Chlorhexidine, 3)500ppmNaF and 4)Comb. Resazurin, colony-forming-units(CFU) and Transversal Microradiography(TMR) were performed. RESULTS: The proteomic results revealed higher quantity of proteins in the Comb compared to control associated with immune system response and oral microbial adhesion. Microbiome showed a significant increase in bacteria linked to a healthy microbiota, in the Comb group. In the in vitro study, Comb group was only efficient in reducing mineral-loss and lesion-depth compared to the PBS. CONCLUSIONS: The AEP modification altered the subsequent layers, affecting the initial process of bacterial adhesion of pathogenic and commensal bacteria, as well as enamel demineralization. CLINICAL RELEVANCE: Comb group shows promise in shaping oral health by potentially introducing innovative approaches to prevent enamel demineralization and deter tooth decay.

Microbial shift of oral biofilm associated with remineralization of root dentin lesions.

PURPOSE: To examine the relationship between remineralization of incipient root dentin lesions and the presence of polymicrobial biofilms, as well as examine changes in microbial composition. METHODS: Bovine root dentin disks used as specimens for biofilm formation, were cultured using saliva from a single donor. Amsterdam Active Attachment biofilm model was used to grow biofilms. The culture medium was McBain 2005 with 0.2% sucrose and 0.4 ppm F as sodium fluoride. After cultivation for 48 hours to achieve demineralization, a control group (n=10) was obtained and the other specimens were further cultured for 336 hours in two types of remineralization culture medium, with sucrose (S+) and without sucrose (S-), through continuous anaerobic incubation (10% CO2,10% H2, 80% N2). Then half of the specimens cultured in the S- medium were transferred to the S+ medium for an additional 48 hours resulting in three experimental groups S(+) (n=10), S(-) (n=10), and S(-)de (n=10), respectively. Experiment 1: Transverse microradiography (TMR) analysis - Immediately after respective culture treatments, integrated mineral loss (IML) and lesion depth (LD) in the dentin specimens were analyzed by TMR. Experiment 2: Microbiome analysis - Sequence data of the 16S rRNA gene of each sample was obtained using MiSeq, and partial base sequences were determined. Next-generation sequencing was performed to determine the taxonomic groups of fungi present in the biofilm samples. RESULTS: Experiment 1: In the control group, formation of dentin demineralization lesions by polymicrobial species biofilms was confirmed. The S(-) group showed significantly decreased IML and shallower LD compared to the control group. The S(-)de group showed a significant increase in IML and LD compared to the S(-) group. Experiment 2: There were statistically significant differences in microbiome between the control group and each of the three experimental groups, both at the genus and species levels. A significant difference in genus was observed between the S(-) group and the S(-)de group. CLINICAL SIGNIFICANCE: The confirmation of the possibility of microbial shift occurring during the remineralization process of root caries will lead to the development of new remineralization therapies.

Carbon dots combined with phytosphingosine inhibit acid-induced demineralization of hydroxyapatite in vitro.

OBJECTIVES: To study the effects of carbon dots (CDs), in combination with phytosphingosine (PHS), against acid-induced demineralization of hydroxyapatite in vitro. METHODS: CDs were generated from citric acid and urea by microwave heating. Transmission electron microscope (TEM), FT-IR, and fluorescence intensity were used to characterize the CDs. A hydroxyapatite (HAp) model was used to investigate the protective effects of CDs, PHS, and their combinations with and without a salivary pellicle against acid-induced demineralization in vitro. Ca2+ release as a parameter to evaluate the inhibition of demineralization was measured by capillary electrophoresis. The interactions between CDs, PHS, and HAp discs were investigated using a fluorescence detector. RESULTS: Uniform-sized CDs were synthesized, showing typical optical characteristics. CDs exhibited no inhibition of acid-induced demineralization in vitro, in contrast to PHS. Notably, a pre-coating of CDs increased the protective effects of PHS against acid-induced demineralization, which was not disturbed by the presence of a salivary pellicle and Tween 20. Scanning electron microscope (SEM) confirmed the binding and layers formed of both CDs and PHS to the HAp surfaces. Based on fluorescence spectra CDs binding to HAp seemed to be dependent on Ca2+ and PO43- interactions. CONCLUSIONS: CDs combined with PHS showed protective effects against acid-induced demineralization of HAp discs in vitro.

Effect of phosphoric acid containing polyvinylpyrrolidone as protective etchant for dentin bonding.

STATEMENT OF PROBLEM: Phosphoric acid is commonly used in dentistry as an etchant but can result in excessive demineralization of dentin, a major contributor to the instability of dentin-bonded restorations. Nevertheless, research on the development of etchants that can reduce acid damage is sparse. PURPOSE: The purpose of this in vitro study was to investigate the effects of polyvinylpyrrolidone-modified phosphoric acid on the dentin bonding of an etch-and-rinse adhesive. MATERIAL AND METHODS: Protective etchants were prepared by adding polyvinylpyrrolidone to 35% phosphoric acid aqueous solutions: the 3 concentrations were 0.5% (P0.5% group), 1% (P1% group), and 2% (P2% group) w/v. The treatment agent of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), microhardness, microtensile bonding strength (µTBS), nanoleakage, and in situ zymography were used to evaluate the appearance of the protective etchant on dentin bonding. The results were analyzed with a 1-way ANOVA test (α=.05). RESULTS: SEM showed no obviously exposed collagen fiber in the P1% and P2% groups. FTIR showed less demineralization of the dentin surface, and microhardness was higher after treatment with the protective etchant (P<.05). The µTBS of P1% (70 ±9.2 MPa) was the highest, and group C (44 ±5.8 MPa) was the lowest in all groups (P<.05). Moreover, there was weaker MMP activity in the P1% and P2% groups (P<.05). CONCLUSIONS: This study demonstrated that the protective etchant effectively reduced demineralization, enhanced bond strength, and reduced nanoleakage and enzyme activity within the hybrid layer.

Pomegranate extract in polyphosphate-fluoride mouthwash reduces enamel demineralization.

OBJECTIVES: To evaluate the anti-demineralizing effect of a mouthwash comprising pomegranate peel extract (PPE 3%), sodium trimetaphosphate (TMP 0.3%), and fluoride (F 225 ppm) in an in situ study, and to assess its irritation potential in an ex vivo study. METHODS: This double-blind crossover study was conducted in four phases with 7 days each. Twelve volunteers used palatal appliances containing enamel blocks, which were subjected to cariogenic challenges. The ETF formulation (PPE + TMP + F, pH 7.0), TF formulation (TMP + F, pH 7.0), deionized water (W, pH 7.0), and essential oil commercial mouthwash (CM, 220 ppm F, pH 4.3) were dropped onto the enamel twice daily. The percentage of surface hardness loss, integrated loss of subsurface hardness, calcium, phosphorus, and fluoride in enamel and biofilms were determined. In addition, alkali-soluble extracellular polysaccharide concentrations were analyzed in the biofilms. The irritation potential was evaluated using the hen's egg chorioallantoic membrane test through the vascular effect produced during 300-s of exposure. RESULTS: ETF was the most efficacious in preventing demineralization. It also showed the highest concentrations of calcium and phosphorus in the enamel and in the biofilm, as well as the lowest amount of extracellular polysaccharides in the biofilm. In the eggs, ETF produced light reddening, whereas CM led to hyperemia and hemorrhage. CONCLUSIONS: The addition of PPE to formulations containing TMP and F increased its anti-demineralizing property, and this formulation presented a lower irritation potential than the CM. CLINICAL RELEVANCE: ETF can be a promising alternative alcohol-free mouthwash in patients at high risk of caries.

Effect of nanometric ß-calcium glycerophosphate supplementation in conventional toothpaste on enamel demineralization: An in vitro study.

The aim of this study was to evaluate the effects of supplementing toothpastes containing 1100 ppm F with micrometric or nanometric [beta]-calcium glycerophosphate (ß-CaGPm/ß-CaGPn) on artificial enamel demineralization, using a pH cycling model. Bovine enamel blocks (4 mm × 4 mm, n = 120) selected using initial surface hardness were randomly allocated to ten toothpaste groups (n = 12): without fluoride or ß-CaGPm or ß-CaGPn (Negative control), 1100 ppm F (1100 F), and 1100 ppm F plus 0.125%, 0.25%, 0.5%, and 1.0% of ß-CaGPm or ß-CaGPn. Blocks were treated two times per day with toothpaste slurry and subjected to five pH cycles (demineralizing and remineralizing solutions) at 37 °C. The final surface hardness, percentage of surface hardness loss (%SH), cross-sectional hardness (ΔKHN), and profile analysis and lesion depth subsurface were analysed using polarized light microscopy (PLM). Fluoride (F), calcium (Ca), and phosphorus (P) concentrations were also measured. Data were analysed using ANOVA and Student-Newman-Keuls tests ([alpha] = 0.001). Blocks treated with 1100 F toothpaste containing 0.5%ß-CaGPm or 0.25%ß-CaGPn showed with reduced %SH values when compared with those treated with 1100 F alone (p < 0.001). Reduced lesion depths (ΔKHN and PLM) were observed for the slurry made up of 1100 F and 0.25%ß-CaGPn (p < 0.001). The addition of ß-CaGPm and ß-CaGPn did not influence the enamel F concentration, with the 1100 F/0.25%ß-CaGPn group exhibiting the highest Ca and P enamel concentrations (p < 0.001). Based on the findings of this in vitro study, we can conclude that the fluoride toothpaste produced a superior effect when combined at an appropriate ß-CaGP molar ratio. This effect was achieved with a lower proportion of ß-CaGP in the form of nanometric particles.

Effect of calcium-coacervate infiltration of artificial enamel caries lesions in de- and remineralizing conditions.

OBJECTIVES: Calcium-coacervate emulsions (CC) might be considered as mineral precursors to foster remineralization of carious dental hard tissues. This study analyzed the instant effect of repeated infiltration of artificial caries lesions with a CC emulsion as well as the effects of subsequent exposure of CC-infiltrated lesions to demineralizing and remineralizing environments. METHODS: Bovine enamel specimens were partly covered with varnish to leave three exposed windows. Artificial enamel caries lesions were created (pH 4.95, 17d). Baseline controls (BL) were obtained by preparing a thin section of each specimen. Specimens were allocated to five groups. In three groups lesions were etched with 37 % phosphoric acid gel, infiltrated with dipotassium hydrogen phosphate and subsequently with a calcium coacervate emulsion, prepared by mixing CaCl2 ⋅ 2H2O with polyacrylic acid sodium salt (PAA-Na). Subsequently, the infiltration effect was either analyzed immediately (Inf.) or after exposition to either de- (Inf.+DS) or remineralizing solution (Inf.+RS) for 10 or 20 days, respectively. In two control groups specimens were exposed to either DS or RS, respectively without prior CC infiltration. Integrated mineral loss [ΔZ(vol%×µm)] was analyzed using transverse microradiography (TMR). RESULTS: Infiltration of enamel caries lesions with coacervate solution resulted in only subtle immediate mineral gain even if repeated. When exposed to demineralizing conditions, infiltrated lesions showed significantly less mineral loss compared to untreated controls (p < 0.05; Kruskal Wallis) and exhibited characteristic mineral depositions within the lesion body. CONCLUSIONS: While immediate mineral gain by infiltration was only modest, the CC-emulsion might be able to prevent demineralization in acidic conditions. CLINICAL SIGNIFICANCE: Calcium coacervates might act protective against further demineralization when infiltrated into enamel caries lesions.

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

OBJECTIVE: The article reviewed novel orthodontic devices and materials with bioactive capacities in recent years and elaborated on their properties, aiming to provide guidance and reference for future scientific research and clinical applications. DATA, SOURCES AND STUDY SELECTION: Researches on remineralization, protein repellent, antimicrobial activity and multifunctional novel bioactive orthodontic devices and materials were included. The search of articles was carried out in Web of Science, PubMed, Medline and Scopus. CONCLUSIONS: The new generation of orthodontic devices and materials with bioactive capacities has broad application prospects. However, most of the current studies are limited to in vitro studies and cannot explore the true effects of various bioactive devices and materials applied in oral environments. More research, especially in vivo researches, is needed to assist in clinical application. CLINICAL SIGNIFICANCE: Enamel demineralization (ED) is a common complication in orthodontic treatments. Prolonged ED can lead to dental caries, impacting both the aesthetics and health of teeth. It is of great significance to develop antibacterial orthodontic devices and materials that can inhibit bacterial accumulation and prevent ED. However, materials with only preventive effect may fall short of addressing actual needs. Hence, the development of novel bioactive orthodontic materials with remineralizing abilities is imperative. The article reviewed the recent advancements in bioactive orthodontic devices and materials, offering guidance and serving as a reference for future scientific research and clinical applications.

Xylitol associated or not with fluoride: Is the action the same on de- and remineralization?

OBJECTIVES: This study evaluated the effect of xylitol combined or not with fluoride (F) on reduction of demineralization and increase of remineralization of shallow and deep artificial enamel lesions. METHODS: Bovine enamel samples were allocated to the following solutions groups: no xylitol (negative control), 5% xylitol, 10% xylitol, 20% xylitol, 500 ppm F (as NaF), 5% xylitol+F, 10% xylitol+F or 20% xylitol+F (n = 12-15). For the demin study, a pH-cycling model (demineralization-6 h, pH 4.7/remineralization 18 h, pH 7.0) was employed for 7 days. Treatments were applied 2 × 1 min. In the remin study, specimens were pre-demineralized for 2, 5 or 10 days. Afterwards, a pH-cycling protocol was conducted (2 h demineralizing and 22 h remineralizing solution/day for 8 days) and the same treatments were done. The response variables were percentage surface hardness loss (%SHL) and transverse microradiography. Data were analyzed by RM ANOVA/Tukey or Kruskal-Wallis/Dunn (p < 0.05) RESULTS: F and Xylitol combined with F reduced the %SHL (23-30%) compared to the negative control (61.5%). The integrated mineral loss and the lesion depth were not reduced by any treatment. Surface hardness recovery was seen only for shallow lesions in case of 20% xylitol+F compared to negative control. No lesion depth recovery, but significant mineral recovery was seen for F (2-days and 10-days lesion). CONCLUSIONS: All concentrations of xylitol+F reduced enamel surface demineralization, while only 20% xylitol+F improved surface remineralization of shallow lesions in vitro. CLINICAL SIGNIFICANCE: Our results suggest that while F or any concentration of xylitol + F reduces surface demineralization, only 20% xylitol+F improves surface remineralization of shallow lesions in vitro. Therefore, xylitol may be added into oral products, combined to F, to control dental caries.

Influence of the orthodontic bonding procedure on biofilm formation.

INTRODUCTION: In orthodontics, white spot lesions are a persistent and widespread problem caused by the demineralization of buccal tooth surfaces around bonded brackets. The remaining adhesive around the brackets leads to surface roughness, which might contribute to demineralization. The present in vitro study aimed to compare a conventional and a modern adhesive system (APC Flash-Free technology) for orthodontic brackets with regard to the adhesion of Streptococcus sobrinus, a leading caries pathogen. METHODS: This in vitro study included 20 premolar teeth and compared 10 APC Flash-Free adhesive-coated ceramic brackets (FF)with 10 conventionally bonded (CB) ceramic clarity brackets. Specimens were incubated in an S. sobrinus suspension for 3 h. To evaluate the bacterial formation, samples were analysed with a scanning electron microscope (SEM). Imaging software was used to quantify and statistically compare percentage values of colonization (PVC) in both groups' adhesion and transition areas. RESULTS: We found a significant difference in biofilm formation between the groups for the adhesive and transition areas. PVC in the adhesive area was approximately 10.3-fold greater for the CB group compared with the FF group (median: 3.2 vs 0.31; P < 0.0001). For the transition area, median PVC was approximately 2.4-fold greater for the CB group compared with the FF group (median: 53.17 vs 22.11; P < 0.01). CONCLUSIONS: There was a significantly lower level of S. sobrinus formation around the FF bracket system than there was surrounding the conventionally bonded group. This study suggests that the FF adhesive bracket system can help reduce the occurrence of bacterial growth around orthodontic brackets.

A glycol chitosan derivative with extrafibrillar demineralization potential for self-etch dentin bonding.

OBJECTIVES: Extrafibrillar demineralization is an etching technique that removes only minerals from around the collagen fibrils for resin infiltration. The intrafibrillar minerals are left intact to avoid their replacement by water that is hard for adhesive resin monomers to displace. The present work reported the synthesis of a water-soluble methacryloyloxy glycol chitosan-EDTA conjugate (GCE-MA) and evaluated its potential as an extrafibrillar demineralization agent for self-etch dentin bonding. METHODS: Glycol chitosan-EDTA was functionalized with a methacryloyloxy functionality. Conjugation was confirmed using Fourier transform-infrared spectroscopy. The GCE-MA was used to prepare experimental self-etch primers. Extrafibrillar demineralization of the primers was evaluated with scaning electron microscopy and transmission electron microscopy. The feasibility of this new self-etch bonding approach was evaluated using microtensile bond strength testing and inhibition of dentin gelatinolytic activity. The antibacterial activity and cytotoxicity of GCE-MA were also analyzed. RESULTS: Conjugation of EDTA and the methacryloyloxy functionality to glycol chitosan was successful. The functionalized conjugate was capable of extrafibrillar demineralization of mineralized collagen fibrils. Tensile bond strength of the experimental self-etch primer to dentin was comparable to that of phosphoric acid-etched dentin and the commercial self-etch primer Clearfil SE Bond 2. The GCE-MA also inhibited soluble rhMMP-9. In-situ zymography detected minimal fluorescence in hybrid layers conditioned with the experimental primer. The GCE-MA was noncytotoxic and possessed antibacterial activities against planktonic bacteria. SIGNIFICANCE: Synthesis of GCE-MA brought into fruition a self-etch conditioner that selectively demineralizes the extrafibrillar mineral component of dentin. A self-etch primer prepared with GCE-MA achieved bond strengths comparable to commercial reference adhesive systems.

Impact of Molar Incisor Hypomineralization on Oral Health-Related Quality of Life in Brazilian Schoolchildren Aged 8 to 10 Years

ABSTRACT Objective: To assess the impact of Molar Incisor Hypomineralization (MIH) and confounding factors on oral health-related quality of life (OHRQoL) according to the perception of 8 to 10-year-old children and their parents/caregivers. Material and Methods: A cross-sectional study including 403 students aged 8-10 years was carried out, in which OHRQoL was measured using the Child Perceptions Questionnaire administered to both children and parents/caregivers. The diagnosis of MIH was performed according to the previously proposed index. Dental caries experience, malocclusion, and sociodemographic factors were evaluated as confounders. Cluster analysis and Poisson regression with robust variance (p<0.05) were performed. Results: The prevalence of MIH was 13.4%. Parents/caregivers of children with MIH in incisors showed a higher impact prevalence in the emotional well-being domain (PR=1.92; 95%CI=1.16-3.19). Children with hypoplasia had a higher prevalence of negative impact on OHRQoL in the oral symptoms domain (PR=1.51; 95%CI=1.03-2.23). According to the perception of parents/caregivers, dental caries experience had a negative impact on the quality of life of students in the emotional well-being domain (PR=4.19; 95%CI=1.06-16.49) and in the total questionnaire score (PR=3.21; 95%CI=1.06-9.71). Conclusion: According to the perception of parents/caregivers, children with MIH in incisors showed a greater impact on OHRQoL. Additionally, the presence of hypoplasia affected the self-perception of OHRQoL in children, and caries experience influenced the OHRQoL of children, as perceived by parents/caregivers.

Estimation of the Efficacy of Remineralizing Agents on the Microhardness of Deciduous Teeth Demineralized Using Pediatric Formulations.

AIM: This study aimed to evaluate the demineralizing effect of commonly used pediatric syrup formulations on primary teeth and the efficacy of two readily available remineralizing agents in treating this effect. MATERIALS AND METHODS: Ninety primary teeth were used for sample preparation and divided into three groups: antibiotic syrup (group A), cough syrup (group B), and control (group C) groups. These groups were further categorized into intragroups according to the treatment with remineralizing agents: groups A1, B1, and C1 received GC Tooth Mousse (casein phosphopeptide-amorphous calcium phosphate, CPP-ACP paste) and groups A2, B2, and C2 received Clinpro Tooth Crème. The samples were subjected to a series of demineralization cycles for 14 days, and remineralization cycles until 30 days were performed using two remineralizing agents, that is, GC Tooth Mousse (CPP-ACP paste) and Clinpro Tooth Crème and were evaluated using Vicker's microhardness test. RESULTS: Antibiotic syrup (group A) and cough syrup (group B) showed a significant decrease in surface microhardness compared with control (group C). All intragroups showed an increase in surface microhardness after treatment with remineralizing agents, which was significantly higher in intragroups A1, B1, and C1 treated with GC Tooth Mousse (CPP-ACP paste). CONCLUSIONS: Oral liquid medications showed definite demineralization potential. CPP-ACP paste was found to be better than Clinpro Tooth Crème for demineralized teeth. CLINICAL SIGNIFICANCE: The use of over-the-counter drugs has increased among the average Indian population, especially for the treatment of fever, cold, and cough. Unwise use of medications by the present population without proper medical guidance will lead to irreparable changes in future generations.

Efficacy of ClinproTMXT Varnish surrounding brackets on the enamel surface of white spot lesion.

Orthodontics patients usual develop demineralization and present cavity caries lesions after six months. Minimally invasive procedures have been the goal in modern dental practice. The aim of this study was to evaluate the effect of ClinproTMXT Varnish, on the enamel surface roughness and severity of white spot lesions. Twenty premolars were submitted to bond brackets and experimental induction of demineralization and randomly divided into 2 groups: GI - fluoride varnish (Colgate Duraphat®); GII - Ionomeric Sealant (ClinproTMXT Varnish). The treatment was applied around the brackets. The surface roughness of specimens was analyzed, before treatment and 12 weeks after treatment by laser confocal microscopy, and the severity of the white spot lesion was by laser fluorescence device. The data were analyzed by non-parametric Wilcoxon and Mann-Whitney Test, at 5% significance, roughness percentage reduction was performed. The severity of demineralization decreased in both, GI (p = 0.005) and GII (p = 0.019). Enamel superficial roughness levels decreased in GI and GII. As well as the roughness percentage, being more expressive in the ClinproTMXT Varnish group (85,09%). Colgate Duraphat® or Clinpro™ XT Varnish reduced the severity of the demineralization and decreased the superficial roughness on the enamel. The Clinpro™ XT Varnish was superior to superficial roughness on enamel.

Evaluation of flexural strength, degree of conversion, and demineralization-prevention properties in adjacent tooth structures of an experimental fissure sealant containing nano-calcium-phosphate compounds.

BACKGROUND: The present study aimed to evaluate the flexural strength, degree of conversion, and demineralization-prevention ability of an experimental fissure sealant containing nano-calcium-phosphate compounds. METHODS: An experimental sealant was formulated using silica and nano hydroxyapatite filler particles. The control group consisted of the DENU Seal (n = 10, each group). The flexural bond strength was evaluated by UTM. DC was evaluated by FTIR. To evaluate the demineralization-prevention ability, Cl V cavities in 10 third molar teeth restored with two sealant products, followed by an acid challenge then the Vickers microhardness test was carried out. RESULTS: The mean flexural strength in the commercial group was higher than the experimental group. However, the mean flexural modulus was not significantly different between the two groups. In the experimental group, DC was significantly higher than the commercial group. Adjacent to the interface, the decrease in microhardness in the experimental group was significantly less than the commercial group. However, on the tooth surface, there were no significant differences between the two groups. In the experimental group, the decrease in microhardness at the interface was less than at the tooth surface, however the situation was opposite in the commercial group. CONCLUSIONS: Incorporating hydroxyapatite into the sealant structure might prevent demineralization, without adverse effects on flexural modulus and degree of conversion.

Effects of silver diamine fluoride on demineralization protection after a secondary acid challenge.

OBJECTIVE: This investigation describes the effects of 5% sodium fluoride varnish and 38% silver diamine fluoride on demineralization protection of human enamel lesions of three different severities after a secondary acid challenge. STUDY DESIGN: Specimens underwent color and enamel surface microhardness change measurements after demineralization and treatment events. Transverse microradiography was conducted following the secondary demineralization. RESULTS: After treatments, enamel surface microhardness change showed that 24-hour lesions treated with fluoride varnish had less rehardening than 24-hour lesions treated with silver diamine fluoride (p<0.05), whereas 144-hour lesions from both treatment groups showed a beneficial decrease in surface microhardness change that was markedly better in samples treated with silver diamine fluoride (p<0.05). After the secondary demineralization, 24- and 144-hour lesions treated with silver diamine fluoride showed a sustained beneficial decrease in enamel surface microhardness change when compared to fluoride varnish-treated samples of the corresponding lesion severity (p<0.05). Transverse microradiography showed no difference between fluoride varnish- and silver diamine fluoride-treated samples of any corresponding lesion severity, indicating that remineralization in both fluoride varnish- and silver diamine fluoride-treated samples was proportional to each other after a secondary acid challenge. CONCLUSIONS: Using silver diamine fluoride may have comparable benefits to fluoride varnish in mineral loss prevention.

[Application of autofluorescence microscopy and laser Induced fluorescence methods to study the dynamics of the demineralization primary teeth process in vitro]. / Primenenie autofluorestsentnoi mikroskopii i lazernoi fluometrii dlya izucheniya protsessa demineralizatsii vremennykh zubov in vitro.

OBJECTIVE: Improvement of methods for studying the processes of demineralization of hard tissues of temporary teeth. MATERIAL AND METHODS: The study included primaries second molars (n=11). Samples of primary teeth were placed in a test tube with a demineralizing solution for - 1, 4, 8, 21 and 31 days. The of primary teeth samples were examined using methods - laser induced fluorescence (LIF) and autofluorescence microscopy (AFM). Assessment of the degree of demineralization of samples of temporary teeth was carried out according to the score scale developed by us. RESULTS: The enamel of the samples is demineralized slowly and evenly for up to 8 days with minimal objective signs, starting from the 8th day of the experiment, there is a significant increase in demineralization indicators. By the 21st day, the peak of demineralization is reached with partial dissolution of the enamel, an increase in the fluorescence effect to 80 UE, and reaches a maximum of 4 points on the evaluation scale. Dentin's hard tissues are demineralized gradually without "sudden jumps" in the fluorescence effect and at the same rate throughout the experiment, reaching a maximum on 31 days (30 UE - LIF). Dentin demineralization is characterized by less dissolution, however, the phenomenon of delamination is determined by the type of exfoliation of the organic dentin matrix, starting from the 21st day of the experiment. CONCLUSION: Enamel and dentin of deciduous teeth demineralize at different rates and have a characteristic specificity of morphological changes. Logistic regression analysis showed the consistency of the classifier for the predictive accuracy of each unit of the proposed scale for assessing the degree of demineralization of temporary teeth samples.

[The results of the study of the focus of initial caries of human tooth enamel in vitro using atomic force microscopy]. / Rezul'taty issledovaniya ochaga nachal'nogo kariesa emali zuba cheloveka in vitro s pomoshch'yu atomno-silovoi mikroskopii.

OBJECTIVE: Identify structural disorders of the surface of the enamel of a human tooth during the development of the carious process in the «white spot¼ stage using atomic force microscopy (AFM). MATERIAL AND METODS: The studies were carried out on 10 molar samples in areas with initial caries in the white spot stage. 6 areas of initial caries were scanned using the atomic force microscope Cetus Light (Nano Scan Technology, Russia) in semi-contact mode. Criteria were proposed for comparing the results of AFM scanning of tooth enamel surface samples and, based on them, the nature of the main structural disorders of the enamel surface in the affected area was determined. RESULTS: For all the samples studied, the healthy enamel surface was smoother compared to the enamel in the area of the clinically visible «white spot¼ and in the immediate vicinity of it. The heterogeneity of the enamel surface in the center of the white spot¼ for all the samples studied was at least 60% higher than at the edge of the process. It was revealed that the heterogeneity of the surface outside the clinically visible white spot at a distance of less than 1 mm from its perimeter is at least 30% higher than that of healthy tissue of the same tooth. It is shown that the heterogeneity of the enamel surface in the center of the caries area in the white spot stage is at least 4 times greater than the heterogeneity of the surface of the healthy enamel of the same tooth, which indicates its demineralization. CONCLUSION: The established features of the spread of the initial carious process can be used in clinical practice for the diagnosis and dynamic observation of the processes of enamel demineralization.

CO2 laser irradiation combined with fluoridated dentifrice improved its protective effect on caries lesion progression regardless of the acidulated phosphate fluoride gel application: An in situ study.

OBJECTIVE: This in situ study aimed to investigate the efficacy of CO2 laser at a 10.6-µm wavelength combined with 1.23% acidulated phosphate fluoride (APF) and fluoridated dentifrice with 1100 µg F/g (FD) to control enamel caries progression. MATERIALS AND METHODS: Sixteen volunteers wore palatal appliances containing eight demineralized enamel specimens for four 14-day phases under sucrose exposure. These specimens were submitted to CO2 laser irradiation and APF alone or combined with FD. Treatment groups were non-fluoridated dentifrice-NFD, NFD + CO2 laser, NFD + APF, NFD + CO2 laser + APF, FD, FD + CO2 laser, FD + APF, and FD + CO2 laser + APF. Mineral loss, calcium fluoride (CaF2), fluorapatite (FAp), and fluoride in the biofilm were analyzed by analysis of variance followed by the Student-Newman-Keuls test, p < 0.05. RESULTS: The highest mineral loss inhibition was noted when FD and CO2 laser irradiation were combined, which did not significantly differ from the FD + CO2 laser + APF group. The CaF2, FAp, and F in the biofilm were more pronounced when the FD and APF were combined. The CO2 laser irradiation promoted a slightly higher concentration of CaF2 in the enamel and F in the biofilm. CONCLUSION: Although APF promotes the high formation of CaF2 and FAp, the combined use of FD with CO2 laser overcomes the APF effect in inhibiting the progression of artificial caries-like lesions in situ. CLINICAL SIGNIFICANCE: Under the in situ design of this study, remineralization of white spot lesions was achieved through CO2 laser irradiation and daily use of fluoridated dentifrice. Future clinical trials are encouraged to substantiate this finding.

Effect of composite resin containing antibacterial filler on sugar-induced pH drop caused by whole saliva bacteria.

STATEMENT OF PROBLEM: Secondary caries around restorations is a major problem and can be attributed to bacteria invading microgaps formed at the tooth-restoration interface. An antibacterial composite resin containing quaternary ammonium silica (QASi) filler has been reported to inhibit enamel demineralization in situ. However, whether the prevention of enamel demineralization by QASi-containing composite resin is because of the reduced metabolic activity of acid-producing saliva bacteria is unclear. PURPOSE: The purpose of this study was to compare the effects of QASi-containing composite resin and 2 other restorative materials on the viability of salivary bacteria and sugar-induced acid production. MATERIAL AND METHODS: Whole saliva from each of the 30 study participants, 14 at high risk and 16 at low risk for caries, was brought into contact with quadruplicate specimens of 3 restorative materials, Infinix Flowable Composite, an anti-bacterial composite resin containing 1.5% QASi filler (Nobio), Filtek Supreme Flowable Restorative (3M), a conventional flowable composite resin, and dental amalgam (Silmet). Bacterial growth and sugar-induced acid production on each restorative material were measured every 20 minutes for 18 hours. Caries risk groups were compared using the t test and repeated measures analysis of variance (α=.05). When significant, Bonferroni multiple comparisons were used. RESULTS: On average, the saliva with the QASi-containing composite resin specimens maintained a near-neutral pH, not dropping below pH 6.0. The saliva associated with both conventional restorative materials exhibited a pH drop below 5.5 (P<.001), the critical threshold for tooth demineralization according to the Stephan curve. Virtually no growth was measured on the surface of the antibacterial composite resin, whereas bacteria grew on the conventional composite resin and dental amalgam (P<.001). No differences were observed between participants at high and low risk of caries. CONCLUSIONS: Unlike amalgam and conventional composite resin, the QASi-containing composite resin showed a near-complete shutdown of the metabolic activity of salivary bacteria upon contact and virtually no bacterial viability. This suggests that the prevention of tooth demineralization by QASi-containing restoratives is associated with a significant reduction in bacterial metabolic activity.