In vitro effect of S. mutans biofilm on fluoride/MDPB-containing adhesive system bonded to caries-affected primary dentin.

PURPOSE: To evaluate the effect of storage in S. mutans culture or water on the durability of fluoride and MDPB-containing adhesive system on artificial caries-affected primary dentin. METHODS: Dentin flat surfaces of primary molars were submitted to artificial caries development using S. mutans biofilm. CAPD cavities were restored with Adper Scotchbond Multi-Purpose (SBM) or Clearfil Protect Bond (CPB) and they were serially sectioned into sticks (1 mm2 cross-sectional area) and stored in S. mutans biofilm for 3 days, in deionized water for 3 months and afterwards subjected to microtensile bond strength (µTBS) test. A control group was submitted to immediate TBS testing. Two-way ANOVA and Tukey's tests were used. Failure sites were observed by SEM and classified as cohesive (dentin or resin) and adhesive failures. RESULTS: The control group showed the highest µTBS values (MPa) for both SBM (25.2 ± 8.5) and CPB (15.6 ± 6.1) adhesive systems. A significant decrease in µTBS values after S. mutans biofilm and water storage was observed for SBM (18.7 ± 5.7 and 17.4 ± 4.1, respectively) and CPB (13.9 ± 5.2 and 13.7 ± 4.8, respectively), but no difference was found between them. The highest percentage of adhesive failure was observed for all groups. However, cohesive failure in dentin was observed in a higher percentage for SBM than CP.

In vitro effect of calcium nanophosphate and high-concentrated fluoride agents on enamel erosion: an AFM study.

BACKGROUND: Calcium nanophosphate paste can provide ions to remineralize enamel. There are, however, no data available about the remineralizing effect of this paste on the prevention of enamel erosion, when compared with highly concentrated fluoride agents. AIM: To analyze the effect of calcium nanophosphate paste, fluoride gel, and varnish to protect against enamel erosion using surface Knoop hardness (KNH) and atomic force microscopy (AFM). DESIGN: Forty enamel blocks (4 × 4 mm) of third molars were used for 4 groups (n = 10): 1.23% fluoride gel (Fluorgel-DFL(®) ); calcium nanophosphate paste (Desensibilize NanoP-FGM(®) ); fluoride varnish (Duraphat-Colgate(®) ) and control (without agent). The specimens were immersed in cola drink for 5 min and 2 h in artificial saliva, 4× per day for 5 days. The agents were applied before the first erosive cycle. KNH values were obtained before and after the erosive challenge. The surface morphology was evaluated by AFM. anova, Tukey's, and T-Student tests were applied. RESULTS: After erosion, no significant difference was found for KNH among gel, nanophosphate, and varnish groups; however, they showed higher KNH than control group. Gel and nanophosphate paste showed a protective layer formation on enamel surface by AFM. CONCLUSIONS: The calcium nanophosphate paste showed similar protection against enamel erosion compared with high-concentrated fluoride agents, even containing lower fluoride concentration.

Effect of four different mono and multi-wave light-curing units on the Knoop hardness of veneer resin composites.

OBJECTIVES: To evaluate the effect of mono and multi-wave light-curing units (LCUs) on the Knoop hardness of resin-based composites (RBC) that use different photoinitiators. METHODS: Central incisor-shaped specimens 12 mm long, 9 mm wide, and 1.5 mm thick were made from 2 RBCs that use different photoinitiators: Tetric N-Ceram (Ivoclar Vivadent) - and Vittra APS (FGM), both A2E shade. They were light-cured with 4 different LCUs: two claimed to be multi-wave - VALO Grand (Ultradent) and Emitter Now Duo (Schuster); and two were monowave - Radii Xpert (SDI) and Elipar DeepCure-L (3 M Oral Care) using 2 different light exposure protocols: one 40 s exposure centered over the specimen; and two 20 s light exposures that delivered light from two positions to better cover the entire tooth. 16 groups with 10 specimens in each group were made. The Knoop hardness (KH, kg/mm2) was measured at the top and bottom of the specimen in the center and at the cervical, incisal, mesial, and distal peripheral regions. The active tip diameters (mm) and spectral radiant powers (mW/nm) of the LCUs were measured with and without the interposition of the RBC, as well as the radiant exposure beam profiles (J/cm²) delivered to the top of the RBCs. The data was analyzed using Three-way ANOVA and Tukey's tests (α = 0.05). RESULTS: The VALO Grand (1029 mW) emitted twice the power of the Radii Xpert (500 mW). The KH values of VI and TN resin composite specimens were significantly affected by the LCU used (p < .001), the measurement location (p < .001), and the surface of the specimen (p < .001). LCUs with wider tip diameters produced greater Knoop hardness values at the peripheries of the 12 mm of long, 9 mm wide specimens. In general, the VALO Grand produced the highest KH values, followed by Elipar DeepCure-L, then by Radii Xpert. The Emitter Now Duo LCU produced the lowest values. Exposing the veneers from two locations reduced the differences between the LCUs and the effect of the measurement location. Only the VALO Grand could fully cover the composite veneer with light when the two locations were used. SIGNIFICANCE: The light tip must cover the entire restoration to photocure the RBC beneath the light tip.

Preparation and characterization of NaF/Chitosan supramolecular complex and their effects on prevention of enamel demineralization.

Fluoridated mouthrinse is indicated for individuals with high risk of caries. Chitosan (Chit) exhibits antibacterial properties, but little is known about its effects on enamel when combined with sodium fluoride (NaF) to form NaF/Chit supramolecular complexes. In our study, NaF/Chit supramolecular complexes structured as microparticles were synthetized and characterized, and their effects on human enamel were evaluated after cariogenic challenge simulating the daily mouthrinse use. Initially, NaF/Chit complex formation was investigated based on several titrations by measuring the zeta potential, electrical conductivity (κ), hydrodynamic diameter (Dh), viscosity (η) and heat flow (by isothermal titration calorimetry) against the molar ratio [NaF]/[Chitmonomer], which allowed us to identify the interactions between Chit-NaF with a stoichiometry of approximately 0.68. Spontaneous microparticle formation was observed. Samples of enamel blocks were prepared and divided into eight groups (n = 10/group): (i) 0.2% Chit; (ii) 0.2% NaF; (iii) 0.2% NaF/Chit suspension; (iv) 0.2% acetic acid; (v) 0.05% Chit; (vi) 0.05% NaF; (vii) 0.05% NaF/Chit suspension; and (viii) 0.05% acetic acid. Cariogenic challenge was performed in each sample by cycling in demineralization and remineralization solutions for 7 days. Before each demineralization cycle, the corresponding substances were passively applied daily for 90 s, even in groups with 0.02% concentration. After 7 days, samples were examined for Knoop hardness (KHN) measurements. The data were analyzed by repeated-measures ANOVA and Tukey tests (α = 0.05). The 0.2% NaF and 0.2% NaF/Chit groups showed higher KHNpost-challenge values than the other groups. The 0.2% NaF/Chit microparticle suspension reduced the enamel hardness loss after cariogenic challenge as effectively as the 0.2% NaF solution and demonstrated potential for use in a formulation with anti-caries effects.

Possible Relationship Between the Oral and Gut Microbiome, Caries Development, and Obesity in Children During the COVID-19 Pandemic.

The COVID-19 pandemic has brought health damage and socioeconomic disruptions, together with lifestyle disorders around the world. Children are one of the most commonly affected, mainly due to social isolation and changes in eating habits and physical activities. This way, the risk of weight gain and obesity is possibly enhanced, as well as poor oral hygiene conditions and early childhood caries (ECC) development during the lockdown. In children under 6 years of age, ECC is defined as carious lesions in one or more primary teeth, with or without cavitation. Importantly, alterations in the oral microbiome caused by changes in children lifestyles have much more than a local impact on oral tissues, interplaying with the gut microbiome and influencing systemic environments. Recent studies have been exploring the oral health conditions, eating habits, and weight gain in the childhood population during the COVID-19 pandemic; however, there is a lack of information concerning the association among oral and gut microbiome, dental caries, and obesity in the COVID-19 era. In this context, this review aimed at analyzing a possible relationship between the oral and gut microbiome, caries, and obesity in children during the COVID-19 pandemic.

Synthesis of a chitosan nanoparticle suspension and its protective effects against enamel demineralization after an in vitro cariogenic challenge.

OBJECTIVE: Our study aims to synthesize, characterize, and determine the effects of a ChNPs suspension on human enamel after cariogenic challenge via pH-cycling. METHODOLOGY: ChNPs were synthesized by ion gelation and characterized by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering. Forty enamel blocks were divided into four groups (n=10/group): (i) ChNPs suspension; (ii) chitosan solution; (iii) 0.05% sodium fluoride (NaF) solution; and (iv) distilled water. Specimens were exposed to cariogenic challenge by cycling in demineralization solution (3 h) and then remineralized (21h) for 7 days. Before each demineralization cycle, the corresponding solutions were passively applied for 90 s. After 7 days, specimens were examined for surface roughness (Ra) and Knoop hardness (KHN) before and after the cariogenic challenge; % KHN change (variation between initial and final hardness), and surface topography by an optical profilometer. The data were analyzed by repeated-measures ANOVA, One-way ANOVA, and Tukey tests (α=0.05). RESULTS: TEM images showed small spherical particles with diameter and zeta potential values of 79.3 nm and +47.9 mV, respectively. After the challenge, all groups showed an increase in Ra and a decrease in KHN values. Optical profilometry indicated that ChNPs- and NaF-treated specimens showed uneven roughness interspersed with smooth areas and the lowest %KHN values. CONCLUSION: The ChNPs suspension was successfully synthesized and minimized human enamel demineralization after a cariogenic challenge, showing an interesting potential for use as an oral formulation for caries prevention.

Antimicrobial, mechanical and biocompatibility analysis of chlorhexidine digluconate-modified cements.

BACKGROUND: The focus of this study was to evaluate the antimicrobial, mechanical properties and biocompatibility of glass ionomer (GICs) modified by Chlorhexidine (CHX). MATERIAL AND METHODS: For biocompatibility, 105 male Wistar rats were used, divided into 7 groups (n=15): Group C (Control,Polyethylene), Groups M, M10, M18, and Groups RL, RL10, RL18 (M-Meron and RL-Riva Luting: conventional, and modified with 10%, and 18% CHX, respectively). The tissues were analyzed under optical microscope for different cellular events and time intervals. Antibacterial effect and Shear Bond Strength Test (SBST) were also analyzed. Biocompatibility was analyzed by the Kruskal-Wallis and Dunn tests; SBST one-way ANOVA and Tukey test (P<0.05). For the antibacterial effect, the Kruskal-Wallis and Friedman, followed by Dunn (P<0.05) tests were used. RESULTS: Morphological study of the tissues showed inflammatory infiltrate with significant differences between Groups C and RL18, in the time intervals of 7(P=0.013) and 15(P=0.032) days. The antimicrobial effects of the cements was shown to be CHX concentration-dependent (P=0.001). The SBST showed no significant difference between the Groups of Meron cement (P=0.385), however, there was difference between Group RL and Groups RL10 and RL18 (P=0.001). CONCLUSIONS: The addition of CHX did not negatively influence the SBST. Meron-CHX-10% was the most biocompatible, and Riva-CHX-18% had more influence on the inflammatory process and presented slower tissue repair. Key words:Glass ionomer, chlorhexidine, biocompatibility, antimicrobial properties, microscope.

In Vivo Biocompatibility, Mechanical, and Antibacterial Properties of Cements Modified with Propolis in Different Concentrations.

OBJECTIVES: The focus of this triple-blind randomized study was to evaluate the mechanical properties, antibacterial effect, and in vivo biocompatibility of glass ionomer cements (GICs) modified with ethanolic extracts of propolis (EEP). MATERIALS AND METHODS: For biocompatibility tests, 135 male Wistar rats were used and divided into nine groups: Group C (control, polyethylene), Groups M, M10, M25, M50 (Meron; conventional, and modified with 10%, 25%, 50% EEP, respectively), Groups KC, KC10, KC25, KC50 (Ketac Cem; conventional, and modified with 10%, 25%, 50% EEP, respectively). The tissues were analyzed under an optical microscope for different cellular events in different time intervals. Shear bond strength test (SBST) on cementation of metal matrices (n = 10, per group), adhesive remnant index (ARI) in bovine incisors (n = 10, per group), and antibacterial properties by the agar diffusion test (n = 15, per group) were analyzed. STATISTICAL ANALYSIS: Data were analyzed by Kruskal-Wallis test followed by Dunn, and one-way analysis of variance test followed by Tukey's test (p < 0.5). RESULTS: Morphological evaluation demonstrated intense inflammatory infiltrate in Groups M10 and KC10 in the time intervals of 7 (p = 0.001) and 15 (p = 0.006) days. Multinucleated giant cells were shown to be more present in Group M1, with statistical difference from Control and KC50 Groups in the time interval of 7 days (p = 0.033). The SBST showed no statistical significance among the groups (p > 0.05). Antibacterial property showed a statistically significant difference between Meron and Meron 50%-EEP Groups, and between Ketac and Ketac 50%-EPP Groups (p = 0.001). CONCLUSIONS: The intensity of histological changes resulting from the cements was shown to be inversely proportional to the concentration of propolis added; Ketac 50%-EPP was the concentration that had the most favorable biocompatibility results. Addition of EEP to GIC did not negatively change the SBST and ARI. Antibacterial property demonstrated a concentration-dependent effect.

New generation bulk-fill resin composites: Effects on mechanical strength and fracture reliability.

PURPOSE: To investigate the mechanical performance and fracture reliability of new generation, bulk-fill resin composites of different viscosities. METHODS: Forty sound maxillary premolars were prepared into Class I cavities comprised of 5 mm width × 5 mm length × 5 mm thickness. The teeth were randomly allocated into four groups (n = 10) according to the restorative material: Negative control - without restoration; Positive control - conventional resin composite (Opallis; FGM) was applied using increments of up to 2.0 mm-thick; Bulk-Regular - bulk-fill resin composite of regular viscosity (Opus Bulk Fill; FGM) was applied using a single increment of 5 mm-thick; and Bulk-Flow - a low-viscosity bulk-fill resin composite (Opus Bulk Fill Flow; FGM) was applied as the first increment with ∼3.5 mm-thick, followed by two final increments of Opallis (∼1.5 mm-thick). The teeth were stored at 37 °C, for 24 h, and submitted to a mechanical testing machine (DL500; EMIC) under a compressive loading. Work of fracture (Wf) was also obtained. All data were analyzed using ANOVA and Tukey (α = 5%). Reliability of restorations and probability of failure were analyzed by Weibull analysis. RESULTS: The non-restored teeth showed the weakest behavior of the study. All the restored groups demonstrated similar mechanical properties to each other (p ≥ 0.242). The positive and negative controls failed exclusively within the cohesiveness of enamel/dentin, whereas the bulk-fill-based restorations showed a mixture of cohesive and mixed failures. The restored groups showed an overall similar reliability, although the Bulk-Regular group demonstrated greater characteristic strength than the positive control. CONCLUSION: The novel bulk-fill resin composites of low and regular viscosities show promising application in the restoration of Class I cavities in premolars, demonstrating similar mechanical performance and reliability as compared with restorations prepared using conventional resin composites. From the bulk-fill materials, the version with regular viscosity presented the greatest compliant behavior of the study.

Synthesis and characterization of TPP/chitosan nanoparticles: Colloidal mechanism of reaction and antifungal effect on C. albicans biofilm formation.

In the present study chitosan (Chit) nanoparticles were synthetized by the ionic gelation process, using tripolyphosphate (TPP) as crosslinking agent. The TPP/Chit nanoparticle formation was evaluated by titrations, measuring electrical conductivity (k), zeta potential (ZP), hydrodynamic diameter (Dh), viscosity (η) and heat by isothermal calorimetry (ITC). The antifungal effects were evaluated by C. albicans time-kill assays, inhibition of C. albicans initial adhesion and biofilm formation in comparison with nystatin and chitosan. Conductometric titration exhibited a typical precipitation profile, with an inflection at molar ratio of [TPP]/[Chitmon] ≈ 0.3, suggesting a 1:3.3 stoichiometry. The highest Dh, ZP and η values were shown at the beginning of titrations, due to the intramolecular repulsion between Chit-Chit. With addition of TPP, the values showed gradual reduction, with an intermediary transition at [TPP]/[Chitmon] ≈ 0.16, which was attributed to the partial breakdown of interchain crosslinking and formation of discrete charged aggregates. After this point, reaction should occur by neutralization of these assemblies, causing new reduction in values of Dh, ZP and η until [TPP]/[Chitmon] ≈ 0.3, when they reached their lowest values. ITC experiment also showed the occurrence of two bindings (K1 = 3.6 × 103 and K2 = 7.7 × 104), which were entropy driven. Biological results showed lower C. albicans viability for TPP/Chit over 24 h compared with chitosan and nystatin at MIC and 2 MIC. Moreover, TPP/Chit showed 25-50% inhibition of C. albicans adhesion and biofilm formation. The results showed that TPP/Chit nanoparticles reduced the initial adhesion and biofilm formation of C. albicans and demonstrated potential for use in a formulation for the treatment of oral candidiasis.

Effect of chitosan nanoparticles on the inhibition of Candida spp. biofilm on denture base surface.

OBJECTIVES: Chitosan nanoparticles (ChNPs) have antifungal effects, however there is a lack of information about the effects of ChNPs against Candida biofilm on denture base surface. This study investigated the ChNPs effect against C. albicans biofilm adhesion and formation, and against Candida spp. biofilm on heat-cured acrylic resin. DESIGN: The ChNPs were synthetized (3800 µg/mL) and characterized by infra-red spectrophotometry and transmission electron microscopy. The minimum inhibitory/fungicidal concentrations (MIC/MFC) against Candida spp. were determined. The time-kill assay and changes on C. albicans micromorphology were evaluated. The % inhibition of ChNPs on C. albicans biofilm formation and reduction were investigated using 1 min and 8 h exposure. Candida biofilm was developed on resin surfaces and ChNPs were applied every 8 h for 5 days. After, fungal cells were counted (CFU/mL) and the surface roughness (Ra) and vickers microhardness (HV) of resin were analysed. For all experiments, sodium hypochlorite (NaOCl) was used as control. Data were analyzed by ANOVA, Tukey and paired t-tests (α = 0.05). RESULTS: The MIC80% of ChNPs was 30.1 µg/mL. ChNPs at 4 MIC showed complete inhibition in the time-kill assays. Blastoconidia cells were predominant after ChNPs application. The % inhibition ChNPs on C. albicans was proportional to its concentration, regardless of the exposure time. ChNPs decreased the CFU/mL of Candida spp. and showed lower alteration of HV and Ra values of resin surface compared to NaOCl. CONCLUSIONS: The ChNPs inhibited C. albicans biofilm, reduced Candida biofilm on resin and caused small changes in roughness and hardness of acrylic resin surface.

TiF4 varnish protects the retention of brackets to enamel after in vitro mild erosive challenge.

The effect of fluoride agents on the retention of orthodontic brackets to enamel under erosive challenge is little investigated. The aim of this study was to evaluate the effect of titanium tetrafluoride (TiF4) and sodium fluoride (NaF) agents on the shear bond strength of brackets to enamel and on the enamel microhardness around brackets under erosive challenge. Brackets were bonded to bovine incisors. Five groups were formed according to fluoride application (n=10): TiF4 varnish, TiF4 solution, NaF varnish, NaF solution and control (without application). The specimens were submitted to erosive challenge (90 s cola drink/2h artificial saliva, 4x per day for 7 days). Solutions were applied before each erosive cycle and varnishes were applied once. Vickers Microhardness (VHN) was obtained before and after all cycles of erosion and the percentage of microhardness loss was calculated. Shear bond strength, adhesive remnant index and polarized light microscopy were conducted after erosion. The data were analyzed by ANOVA, Tukey, Kruskal-Wallis and Mann-Whitney U tests (α=0.05). The %VHN had no statistically significant differences among the experimental groups. However, considering the comparisons of all groups with the control group, TiF4 varnish showed the highest protection from enamel demineralization (effect size of 2.94, while the effect size for the other groups was >2.4). The TiF4 varnish group had significantly higher shear bond strength compared to other groups. There was no difference among groups for adhesive remnant index. Polarized light microscopy showed higher demineralization depth for the control group. Application of NaF and TiF4 agents during mild erosive challenge minimized the enamel mineral loss around brackets, however only the experimental TiF4 varnish was able to prevent the reduction of shear bond strength of brackets to enamel.

Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion.

The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM). Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10). The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva). Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukey's test and Student's t test (α = 0.05). After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish.

Weight-loss and surface roughness of enamel after microabrasion procedure with different agents / Perda de peso e rugosidade da superfície do esmalte após procedimento de microabrasão com diferentes agentes

Introduction: Enamel microabrasion is achieved by abrasion of the enamel surface and it is a quick, practical and efficient procedure. Objective It was assessed the weight loss and surface aspect of enamel after microabrasion procedures with commercial and mixtures made in-office. Material and method Eighty bovine incisors were divided into four groups (n=10): OpalustreTM (6.6% HCl + silicon carbide); Whiteness RMTM (6% HCl + silicon carbide); 37% H3PO4 + pumice and 10% HCl + pumice. Treatment was performed by 15 applications of 10s duration. The enamel weight loss was determined by the difference in weight before and after the microabrasion. The surfaces were analyzed by a surface roughness equipment and scanning electron microscopy. Data were submitted to paired-T test, one-way ANOVA and Tukey tests (α=0.05). Result It was observed significantly weight loss for all groups. The difference in weight loss ranged from 0.037±0.012 for group 37% H3PO4 and from 0.054±0.009 for group 6,6% HCl. There was a significant increase in surface roughness for all groups and 10% HCl group showed the lower results (0.65±0.09). It was observed different patterns of enamel morphology by SEM images. Conclusion The in-office mixtures resulted in the lowest enamel structure loss (37% H3PO4) and the lowest surface roughness (10% HCl).

Introdução: A microabrasão do esmalte é realizada através da abrasão da superfície do mesmo, apresentando-se como um procedimento rápido, prático e eficiente. Objetivo Avaliar a perda de peso e o aspecto superficial do esmalte após procedimentos de microabrasão com agentes comerciais e não comerciais. Material e método Oitenta incisivos bovinos foram divididos em quatro grupos (n = 10): OpalustreTM (6,6% HCl + carboneto de silício); Whiteness RMTM (6% HCl + carboneto de silício); 37% H3PO4 + pedra-pomes e 10% HCl + pedra-pomes. O tratamento foi realizado em 15 aplicações de 10s de duração. A perda de peso do esmalte foi determinada pela diferença de peso antes e depois da microabrasão. As superfícies foram analisadas por equipamento de rugosidade superficial e microscopia eletrônica de varredura. Os dados foram submetidos ao teste T-pareado, ANOVA one-way e teste de Tukey (α = 0,05). Resultado Foi observada perda de peso significativa para todos os grupos, a diferença na perda de peso variou de -0,037±0,012 para o grupo 37% H3PO4 a -0.054±0.009 para o grupo 6.6% HCl. Houve um aumento significativo na rugosidade da superfície para todos os grupos e o grupo 10%HCl apresentou os resultados mais baixos (0,65±0,09). Foram observados diferentes padrões de morfologia do esmalte por meio de imagens MEV. Conclusão Os agentes não comerciais resultaram na menor perda de estrutura do esmalte (37% H3PO4) e na rugosidade superficial (10% HCl).

Synthesis of a chitosan nanoparticle suspension and its protective effects against enamel demineralization after an in vitro cariogenic challenge

Abstract Objective Our study aims to synthesize, characterize, and determine the effects of a ChNPs suspension on human enamel after cariogenic challenge via pH-cycling. Methodology ChNPs were synthesized by ion gelation and characterized by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering. Forty enamel blocks were divided into four groups (n=10/group): (i) ChNPs suspension; (ii) chitosan solution; (iii) 0.05% sodium fluoride (NaF) solution; and (iv) distilled water. Specimens were exposed to cariogenic challenge by cycling in demineralization solution (3 h) and then remineralized (21h) for 7 days. Before each demineralization cycle, the corresponding solutions were passively applied for 90 s. After 7 days, specimens were examined for surface roughness (Ra) and Knoop hardness (KHN) before and after the cariogenic challenge; % KHN change (variation between initial and final hardness), and surface topography by an optical profilometer. The data were analyzed by repeated-measures ANOVA, One-way ANOVA, and Tukey tests (α=0.05). Results TEM images showed small spherical particles with diameter and zeta potential values of 79.3 nm and +47.9 mV, respectively. After the challenge, all groups showed an increase in Ra and a decrease in KHN values. Optical profilometry indicated that ChNPs- and NaF-treated specimens showed uneven roughness interspersed with smooth areas and the lowest %KHN values. Conclusion The ChNPs suspension was successfully synthesized and minimized human enamel demineralization after a cariogenic challenge, showing an interesting potential for use as an oral formulation for caries prevention.

A higiene bucal de bebês edêntulos e sua influência na microbiota bucal: os profissionais de saúde devem preconizá-la? ­ revisão crítica / Oral hygiene in edentulous infants and its influence on oral microbiota: should the health professionals recommend it? ­ a critical review

Introdução: A indicação de higiene bucal em bebês edêntulos entre os profissionais de saúde ainda é controversa, sendo necessária a busca científica sobre esta indicação e a padronização da informação. Objetivo: Investigar criticamente as evidências relacionadas a indicação da higiene bucal para bebês edêntulos. Métodos: A busca de artigos foi realizada nas bases de dados PubMed, LILACS e Google Scholar, de modo a avaliar a seguinte pergunta: "A higienização da cavidade bucal de bebês edêntulos pode influenciar a microbiota bucal?". Uma busca em 8 livros de Odontopediatria também foi realizada. Resultados: Foram encontrados 317 artigos (167-PubMed, 146-Google Scholar e 4-LILACS). Não foram encontrados estudos primários que avaliaram o efeito da higiene bucal em bebês edêntulos na microbiota, impossibilitando a condução de revisão sistemática. Assim, para a revisão foram incluídos 6 estudos que investigaram micro-organismos na cavidade bucal de bebês edêntulos e o papel das imunoglobulinas salivares. Dentre os livros avaliados, somente 4 indicaram a higiene bucal em bebês edêntulos. Conclusão: Diante dos dados analisados, não existem estudos primários que avaliaram o efeito da higienização na microbiota bucal de bebês edêntulos. Torna-se relevante a condução de estudos clínicos para obtenção de evidências científicas sobre a indicação ou não da higienização da cavidade bucal de bebês edêntulos.

Introduction: The indication of oral hygiene in edentulous babies is still controversial among health professionals, being necessary the search of this recommendation and the standardization of information. Objective: To inves-tigate critically the evidence related to the indication of oral hygiene for edentulous babies. Methods: The search for articles was performed in the PubMed, LILACS and Google Scholar databases, in order to assess the following question: "Can oral cavity hygiene of edentulous babies influence oral microbiota?" A search in 8 books of Pediatric Dentistry was also performed. Results: 317 articles were found (167-PubMed, 146-Google Scholar and 4-LILACS). There were no primary studies that evalu-ated the effect of oral hygiene of edentulous infants on microbiota, which impair the conduction of a systematic review. Thus, it was included for this review six studies that investigated microorganisms in the oral cavity of edentulous infants and the role of salivary immunoglo- bulins. Among the textbooks evaluated, only 4 indicated the oral hygiene in edentulous infants. Conclusion:According to the data, there are no primary studies that assessed the effect of oral hygiene in the oral microbiota of edentulous babies. It is relevant to conduct clinical studies in order to obtain scientific evidence about the indication or no of the oral hygiene in edentulous babies

In Vitro Effect of Acidic Challenges on the Physical Properties of Dental Prosthesis Artificial Teeth

Abstract Objective: To evaluate the effect of immersion and acid challenge with cola drink on color change (ΔE), Vickers hardness (VHN) and surface roughness (Ra) of artificial acrylic resin teeth. Material and Methods: The artificial teeth were divided into 6 groups (n= 8): TC (Trilux/Control), BC (Biotone/Control), TAC (Trilux/Acid challenge), BAC (Biotone/Acid challenge), TI (Trilux/Immersion) and BI (Biotone/Immersion). The teeth were embedded in acrylic resin and the labial side was serially polished to provide appropriate flat surface. The samples of TC, BC, TI, BI groups were immersed in artificial saliva and cola drink (coke) for 7 days, respectively. The acid challenge was performed with immersion of samples in coke for 5 min, and subsequently immersion in artificial saliva for 2h. This cycle was repeated at 4 times/day, during 7 days. The tests of VHN, ΔE and Ra were analyzed before and after the challenge and immersion groups. Data was analyzed by ANOVA, Tukey and T test (α = 0.05). Results: There was no difference in Ra values between groups after treatments. However, there was a decrease in VHN for all groups. BI (19.2 ± 0.3) presented significantly lower hardness than BAC (19.5 ± 0.9) and BC (20.2 ± 0.5). Groups BI (2.18 ± 0.41) and TI (1.50 ± 0.43) had statistically higher ΔE compared to the other groups. Conclusion: The hardness of resin teeth decreased after acid challenges, but the roughness surface was not affected. The color was more affected by the times of exposure in cola beverage and remineralization in artificial saliva, which were associated to the material degradation (AU).

Effect of hydrochloric acid commercial presentation for microabrasion technique on loss of enamel structure and surface / Efeito da apresentação comercial de ácido clorídrico para técnica de microabrasão na perda de estrutura e superfície do esmalte

Introdução: A técnica de microabrasão pode ser realizada através de pasta pronta para uso, disponível comercialmente, ou o profissional pode manipulá-la no consultório. Objetivo: Verificar o efeito da apresentação comercial do ácido clorídrico a 10% na manipulação de pasta para microabrasão sobre a superfície do esmalte. Metodologia: Foram selecionados incisivos bovinos e divididos em dois grupos, de acordo com a apresentação comercial do ácido clorídrico (líquido ou em gel). O tratamento foi realizado através de dez aplicações com 10s de duração cada, intercaladas por lavagem de 10s. Vinte incisivos (n=10) foram utilizados para se determinar a perda de estrutura do esmalte. Cada amostra foi pesada, em balança analítica, antes e após submissão à microabrasão. Outras 20 amostras (n=10) foram utilizadas para determinação da rugosidade superficial média (Ra) utilizando-se um rugosímetro. Três amostras de cada grupo do experimento anterior foram selecionadas, aleatoriamente, e outras três amostras adicionais foram preparadas como controle (baseline) para análise em MEV. Resultados: Verificou-se diferença estatística significativa entre a massa final e a inicial e rugosidade superficial das amostras, independente da apresentação comercial do ácido. Nas imagens de MEV observou-se presença de superfície regular para o grupo controle (baseline). Nas demais imagens verificou-se superfície com considerável irregularidade e dissolução discreta do esmalte. Conclusões: O tratamento realizado causou perda significativa de estrutura e aumentou a rugosidade superficial dos espécimes, independente da apresentação comercial do ácido e sem apresentar diferença entre os grupos ao final. A apresentação comercial do ácido não parece ser um fator a interferir no tratamento. (AU)

Introduction: The microabrasion technique can be performed using a commercially available paste, or the dentist can prepare it in his office. Objective: To verify the effect of hydrochloric acid commercial presentation in the handling of microabrasion paste on the enamel surface. Methodology: Bovine incisors were divided into two groups, according to the commercial presentation of 10% hydrochloric acid (liquid or gel). The treatment was carried out through ten applications of 10 s duration each, intercalated with a 10s wash. Twenty teeth (n=10) were used to determine the loss of enamel structure. Each sample was weighed on an analytical balance before and after submission to microabrasion. Another 20 teeth (n=10) were used to determine the average surface roughness (Ra) using a rugosimeter. Three samples from each group of the previous experiment were selected, randomly, and another three additional samples were repared as a control (baseline) for SEM analysis. Results: There was a statistically significant difference between the final and initial mass and the surface roughness of the samples, regardless of the acid commercial presentation. In the SEM images, a regular surface was observed for the control group (baseline). In the other images, there was a surface with considerable irregularity and a slight dissolution of the enamel. Conclusions: The treatment carried out. (AU)

Does scientific evidence for the use of natural products in the treatment of oral candidiasis exist? A systematic review.

In view of the limitations of antifungal agents used in the treatment of oral candidiasis and the wide variety of natural products that have been studied as treatment of this disease, this systematic literature review proposed to evaluate whether scientific evidence attesting to the efficacy of natural products in the treatment of this disease exists. A systematic search in PubMed, MEDLINE, SciELO, Lilacs, and Cochrane Library databases was accomplished using the associations among the keywords Candida albicans, phytotherapy, biological products, denture stomatitis, and oral candidiasis in both English and Portuguese. Four independent observers evaluated the methodological quality of the resulting articles. Three studies were included for detailed analysis and evaluated according to the analysis protocol based on the CONSORT (Consolidated Standards of Reporting Trials) 2010 statement. The tested products were different in all studies. Two studies mentioned random samples, but no study described the sample allocation. No study mentioned sample calculations, a prior pilot study, or examiner calibration, and only one trial reported sample losses. Differences between the tested products and the methodological designs among these studies did not allow the existence of scientific evidence related to the effectiveness of these products for the proposed subjects to be confirmed.

Effect of time and pH on physical-chemical properties of orthodontic brackets and wires.

OBJECTIVE: To test the hypothesis that treatment time, debris/biofilm, and oral pH have an influence on the physical-chemical properties of orthodontic brackets and arch wires. MATERIALS AND METHODS: One hundred twenty metal brackets were evaluated. They were divided into four groups (n  =  30) according to treatment time: group C (control) and groups T12, T24, and T36 (brackets recovered after 12, 24, and 36 months of treatment, respectively). Rectangular stainless-steel arch wires that remained in the oral cavity for 12 to 24 months were also analyzed. Dimensional stability, surface morphology, composition of brackets, resistance to sliding of the bracket-wire set, surface roughness of wires, and oral pH were analyzed. One-way analysis of variance, followed by a Tukey multiple comparisons test, was used for statistical analysis (P < .05). RESULTS: Carbon and oxygen were shown to be elements that increased expressively and in direct proportion to time, and there was a progressive increase in the coefficient of friction and roughness of wires as a function of time of clinical use after 36 months. Oral pH showed a significant difference between group T36 and its control (P  =  .014). CONCLUSIONS: The hypothesis was partially accepted: treatment time and biofilm and debris accumulation in bracket slots were shown to have more influence on the degradation process and frictional force of these devices than did oral pH.