Effect of a novel quaternary ammonium methacrylate polymer (QAMP) on adhesion and antibacterial properties of dental adhesives.

This study investigated the resin-dentin bond strength (µTBS), degree of conversion (DC), and antibacterial potential of an innovative adhesive system containing a quaternary ammonium methacrylate polymer (QAMP) using in situ and in vitro assays. Forty-two human third molars were flattened until the dentin was exposed and were randomly distributed into three groups of self-etching adhesive systems: Clearfil™ SE Bond containing 5% QAMP (experimental group), Clearfil™ Protect Bond (positive control) and Clearfil™ SE Bond (negative control). After light curing, three 1 mm-increments of composite resin were bonded to each dentin surface. A total of thirty of these bonded teeth (10 teeth per group) was sectioned to obtain stick-shaped specimens and tested under tensile stress immediately, and after 6 and 12 months of storage in distilled water. Twelve bonded teeth (4 teeth per group) were longitudinally sectioned in a mesio-to-distal direction to obtain resin-bonded dentin slabs. In situ DC was evaluated by micro-Raman spectroscopy. In vitro DC of thin films of each adhesive system was measured using Fourier transform infrared spectroscopy. In vitro susceptibility tests of these three adhesive systems were performed by the minimum inhibitory/minimum bactericidal concentration (MIC/MBC) assays against Streptococcus mutans, Lactobacillus casei, and Actinomyces naeslundii. No statistically significant difference in µTBS was observed between Clearfil™ SE Bond containing 5% QAMP and Clearfil™ SE Bond (p>0.05) immediately, and after 6 and 12 months of water storage. However Clearfil™ Protect Bond showed a significant reduction of µTBS after 12 months of storage (p=0.039). In addition, QAMP provided no significant change in DC after incorporating into Clearfil™ SE Bond (p>0.05). Clearfil™ SE Bond containing 5% QAMP demonstrated MIC/MBC values similar to the positive control against L. casei and A. naeslundii and higher than the negative control for all evaluated bacterial strains. The use of QAMP in an adhesive system demonstrated effective bond strength, a suitable degree of conversion, and adequate antibacterial effects against oral bacteria, and may be useful as a new approach to provide long-lasting results for dental adhesives.

Ultrastructural evaluation of enamel after dental bleaching associated with fluoride.

This study evaluated the effects on human enamel after two bleaching procedures: with a fluoridated bleaching agent and with topical fluoride application postbleaching. It used 43 enamel blocks (3 mm(2) ) that were ground flat (600-2,000 grit) and polished with polishing paste (one and one-fourth). Specimens were randomly divided into three groups according to the bleaching procedure: (1) control group, (2) hydrogen peroxide 35% (HPF) and topical application of fluoride 1.23%, and (3) HP 38% (OP) with fluoride in its composition. Bleaching agents were used according to the manufacturer's instructions. Three methodologies were used: nanoindentation, to observe surface hardness and elastic modulus; atomic force microscopy, to observe surface roughness (R(a) - R(z)); and scanning electron microscopy, to observe the enamel surface effects. Group OP had a decrease in the elastic modulus after bleaching, which was recovered at 14 days. An increased roughness (R(a); 32%) was observed on group HPF and had an increased erosion on enamel surface (67%). It was concluded that topical application of fluoride, after using the nonfluoridated whitening agent, increased the roughness values and erosion of enamel.

Susceptibility of Candida albicans to photodynamic therapy using methylene blue and toluidine blue as photosensitizing dyes.

The increased resistance of Candida albicans to antibiotic therapy indicates the need for alternative treatments for oral candidiasis. Photodynamic therapy (PDT) has been researched as an alternative tool to inactivate pathogenic microorganisms. It uses a combination of a photosensitizer and a visible light source. This study evaluated the susceptibility of C. albicans to PDT and compared the efficacy of 100 microg/mL methylene blue (MB) and toluidine blue (TB) as photosensitizers. The light source was Indium-Gallium-Aluminum Phosphide (InGaAIP) laser at 53 J/cm2. Suspensions of 108 cells/mL of C. albicans were subject to PDT for 5 minutes in 96-well plates, then decimal dilutions were plated on Sabouraud Dextrose agar After 48h incubation at 37 degreesC, the number of CFU/mL were obtained and submitted to statistical analysis using Kolmogorov-Smirnov, ANOVA (p<0.0001) and Tukey tests. The results showed that MB or laser irradiation alone did not have statistically significant antifungal activity compared to the positive control group (p> 0. 05). Conversely, the number of viable C. albicans cells was reduced significantly after PDT using MB or mainly TB associated to diode laser irradiation. The data proved the efficacy of PDT against C. albicans cells, regardless of the photosensitizer used.

Efeito de diferentes agentes clareadores na rugosidade superficial de resinas compostas / Effect of different bleaching agents on surface roughness of composite resins

O presente estudo avaliou o efeito de agentes clareadores na rugosidade superficial de resinas compostas (RC). Foram confeccionados 50 corpos-de-prova, divididos em 10 grupos (n=5). Os grupos G1 ao G5 utilizaram a RC Opallis (microhíbrida); G6 ao G10 a RC Brilliant NewLine (nanohíbrida). Os agentes clareadores foram: PH - Peróxido de hidrogênio 35% (Whiteness HP Max) e PC - Peróxido de carbamida 37% (Whiteness Super). Após 24 horas, realizou-se o clareamento: G1 e G6- sem agente clareador (controles); G2 e G7- uma sessão de PH com três aplicações; G3 e G8- duas sessões de PH com três aplicações cada; G4 e G9- uma sessão de PC com três aplicações e G5 e G10- duas sessões de PC com três aplicações cada. Após o clareamento, os cp foram avaliados no Rugosímetro. Os dados obtidos foram analisados por ANOVA com pós-teste de Bonferroni (α=0,05). Os resultados de rugosidade superficial (μm) foram: G1-0,07±0,02; G2-0,12±0,04; G3-0,40±0,33; G4-0,49±0,65; G5-1,33±1,76; G6-2,03±1,22; G7-1,15±0,46; G8-1,33±1,24; G9-0,56±0,59 e G10-1,87±1,31. Os resultados mostraram que para a RC Opallis, os valores de rugosidade aumentaram após o clareamento e para a RC Brilliant NewLine, os valores diminuíram. Concluiu-se que o uso de agentes clareadores afetou a rugosidade das resinas compostas testadas.

This study evaluated the effect of bleaching agents on surface roughness of composite resins (RC). 50-of-body were made and divided into 10 groups (n=5). In Groups G1 to G5 was used Opallis (a microhybrid RC), and in G6 to G10 Brilliant NewLine (a nanohybrid RC) was used. The bleaching agents were: PH-35% hydrogen peroxide (HP Max Whiteness) and PC-Carbamide peroxide 37% (Whiteness Super). After 24 hours, bleaching was performed: G1 and G6-without bleaching agent (control), G2 and G7-one session with three applications of PH, G3 and G8-two sessions of three applications of HP, G4 and G9-one session with three applications of PC and G5 and G10-two sessions of three applications of PC. After bleaching, specimens were evaluated in a roughness meter. Data were analyzed by ANOVA and Bonferroni's test (α=0.05). The results of surface roughness (μm) were: G1-0.07 ± 0.02, G2-0.12 ± 0.04, G3-0.40 ± 0.33, G4-0.49 ± 0.65; G5-1.33 ± 1.76; G6-2.03 ± 1.22; G7-1.15 ± 0.46; G8-1.33 ± 1.24; G9-0.56 ± 0.59 and G10-1.87 ± 1.31. The results showed that Opallis roughness values increased after bleaching and Brilliant NewLine values decreased. It was concluded that the use of bleaching agents affected the roughness of composite resins tested.

Avaliação clínica do uso de um dessensibilizante antes do clareamento de consultório / Clinical evaluation of a desensitizing agent used before in-office bleeching

Objetivo: avaliar clinicamente o efeito de um agente dessensibilizante utilizado previamente. ià aplicação de um gel de peróxido de hidrogênio 3S% (PH3S) na eficiência do clareamento (EC) ."e sensibilidade dental (50). Material e Métodos: Foram selecionados 30 pacientes divididos em grupo placebo (GP; n=lS) e grupo experimental (GE; n=lS). Um gel placebo ou dessensibilizante (Oesensibilize KF 2%) foi aplicado sobre as superfícies vestibulares dos dentes durante 10 minantes do clareamento com PH3S (Whiteness HP Blue 3S%). Este protocolo foi repetido na l' . e 2' sessões. Os pacientes utilizaram uma escala de O a 4 para anotarem a sensibilidade. A corfoi registrada no início e após a l' e 2' sessões de clareamento usando a escala Vita ordenada por valor. A EC foi analisada estatisticamente pelos testes de análise de variância e de Tukey. A porcentagem de pacientes com 50, assim como a intensidade foram avaliados pelos testes exato de Fisher e Mann-Whitney (a=O,OS), respectivamente. Resultados: O uso de um agente dessensibilizante não afetou a EC (cor B1/A 1 após duas semanas para 90% dos pacientes). 40% e 6,7% dos participantes do GP e GE, respectivamente apresentaram 50 (p < O,OS). A intensidade da 50 foi similar para os grupos (p > O,OS). Conclusão: O uso de um agente dessensibilizante antes do clareamento de consultório reduziu a prevalência de 50.

Objective: To evaluate the bleaching efficiency (BE) and tooth sensitivity (T5) of a desen¬sitizing agent used before in-office bleaching with 3S% hydrogen peroxide gel. Methods: We selected 30 patients for this study, which were divided into placebo and experimental groups. A placebo or desensitizing gel (Oesensibilize KF 2%) was applied on the buccal surfaces of ali teeth for 10 min (n = lS). This protocol was repeated one week later. Patients used a scale of O to 4 to write down their tooth sensitivity. The color was registered before and after the 1 st and 2nd sessions of bleaching using a value-oriented Vita Classical scale. The BE was analyzed by ANOVA and Tukey tests. The % of patients with T5 as well as T5 intensity was analyzed by the Fisher's exact and Mann-Whitney tests (a=O.OS). Results: The use of a desensitizing gel didn 't affect the BE (B 1 /A 1 color after two weeks for 90% of patients). 40% and 6.7% of the participants from the placebo and experimental groups presented T5 (pO.OS). Conclusion: The use of desensitizing gel before in-office bleaching reduced the prevalence of this side effect.

Effects of immersion time and frequency of water exchange on durability of etch-and-rinse adhesive.

This study evaluated the immediate and long-term bond strength to dentin (microtensile bond strength, µTBS) and silver nitrate uptake (SNU) of a three- and two-step etch-and-rinse adhesive under different water immersion times and frequency of water exchange. The adhesives and composite resin were applied according to the manufacturer's instructions in a flat occlusal demineralized dentin of 48 molars. Teeth were assigned to four groups of immersion time (immediate and 1, 3, and 6 months), sectioned to obtain resin-dentin beams, and then subdivided into three groups of water exchange (daily, weekly, and monthly) before being tested in tension. Two resin-dentin beams from each tooth were immersed in silver nitrate and analyzed by SEM. Significant difference in µTBS and SNU was detected for both adhesives (p ≤ 0.0001 for the cross-product interaction). For Adper Single Bond 2, the most pronounced reductions of µTBS were observed for the daily exchange groups in all times. For Adper Scotchbond Multi Purpose, 1-month immersion period was not capable to induce degradation of the dentin bonds, except when the water was exchanged daily. For both adhesives, all storage regimens showed increased SNU results only after 6-month water storage; this being more pronounced for daily water exchange groups. For both adhesives, the highest SNU was observed in the daily water exchange group. The daily water exchange is a fast and reliable in vitro aging method for testing the durability of the adhesive interface produced by adhesive systems.

In vitro analysis of bond strength of self-etching adhesives applied on superficial and deep dentin.

The purpose of this study was to evaluate the bond strength of three adhesive systems to superficial and deep dentine using the microtensile bond strength test (microTBS). The occlusal enamel of thirty human third molars was removed to expose a flat surface of superficial or deep dentin. For each type of surface, the test specimens were randomly divided into three groups which underwent the application of a conventional two-step adhesive system [Single Bond (SB)] as the control group (n=10), a two-bottle self-etching system [One Coat SE Bond (OCSE)] (n=10) and a one bottle one-step system [Clearfil S3 Bond (CFS3)] (n=10). Adhesives were applied, a 5-mm high "crown" as built-up with resin composite Z250 (3M) and the specimens with a cross-sectional area of 0.7 +/- 0.1 mm2 were tested in tension (0.5 mm/min). Four fractured sticks from each tooth were randomly selected and the dentin side was gently abraded with a 1200-grit SiC paper etched with 35% phosphoric acid for 15 s and air dried. SEM micrographs at 70X and 2400X magnification were taken using scanning electron microscopy (SEM) to calculate the area of tubular dentin (ATD) and tubular density (TD) with Image Pro Plus 5. Two-way ANOVA (dentin depth-adhesive) showed higher bond strength values for SB. However the values did not depend on dentin depth. Linear regression showed a significant relationship between bond strength and area of intertubular dentin for SB (p = 0.004), and a significant inverse relationship between tubular density and bond strength for CFS3 (p = 0.009). OCSE exhibited a tendency that was similar to SB and opposite to CFS3, but was not statistically significant. The conventional two-step adhesive had higher bond strength values. The use of digital image analysis facilitates the manipulation of data and contributes to the interpretation of the behavior of new adhesive systems.

Impact of adhesive application and moisture on the mechanical properties of the adhesive interface determined by the nano-indentation technique.

OBJECTIVES: This study assessed the nanohardness (NH) and Young's modulus (YM) of resin-dentin bonding components formed by an ethanol/water-based (Adper Single Bond Plus [SBP]) and an acetone-based system (One Step Plus [OSP]) under different moisture conditions and application methods. MATERIAL AND METHODS: On 24 human molars, a flat, superficial dentin surface was exposed by wet abrasion. After acid-etching, two coats of SBP or OSP adhesive were applied on either a dry or rewetted dentin surface under vigorous rubbing action or inactive application. After polymerization of the adhesives (600 mW/cm2/20 seconds), composite buildups were constructed incrementally and the specimens were stored in water (37 degrees C/24 hours). They were cross-sectioned perpendicular to the resin-dentin interface to obtain 1.5 mm-thick slices that were embedded and polished before the test. Nano-indentations were made on the resin composite, adhesive system, hybrid layer and mineralized dentin. The results of NH and YM (GPa) of the adhesive system and hybrid layer were analyzed using three-way repeated measures ANOVA and Tukey's multiple comparison tests (alpha = 0.05). RESULTS: When the dentin was kept wet, the mode of application did not affect the studied properties within the hybrid layer. On the other hand, the vigorous application mode increased the NH and YM of both adhesives applied in air-dried dentin. In the adhesive layer, the highest NH and YM were observed only for SBP, especially when applied in wet dentin under vigorous action. CONCLUSION: It was concluded that: 1) the vigorous application of both adhesives in dry dentin resulted in high nanohardness and Young's modulus values in the hybrid layer and 2) in the adhesive layer, the moisture associated with the vigorous application mode increased the nanohardness and Young's modulus values of Adper Single Bond Plus.

Repair of furcal perforation with mineral trioxide aggregate: long-term follow-up of 2 cases.

Previous studies have demonstrated the efficacy of mineral trioxide aggregate (MTA) in repair of furcal perforation. In this article, the use of MTA in treating 2 cases of furcal perforation (accidental and caries-related) and subsequent long-term follow-up are described.