Morfologia e espessura da difusão de resina através da matriz de dentina desmineralizada ou sem condicionamento

The formation of a hybrid layer is the main bonding mechanism of current dentin-bonding systems. This study evaluated the morphology and thickness of the resin-infiltrated dentinal layer after the application of adhesive systems. The dentin-bonding agents were evaluated on flat dentinal preparations confected on the occlusal surfaces of human teeth. The test specimens were prepared and inspected under scanning electron microscopy at a magnification of X 2,000. The adhesive systems were responsible for different hybrid layer thicknesses (p < 0.05), and the mean values were: for Scotchbond MP Plus (SM), 7.41 ± 1.24mum; for Single Bond (SB), 5.55 ± 0.82mum; for Etch & Prime 3.0 (EP), 3.86 ± 1.17mum; and for Clearfil SE Bond (CB), 1.22 ± 0.45mum. The results suggest that the conventional three-step adhesive system (SM) was responsible for the thickest hybrid layer, followed by the one-bottle adhesive (SB). The self-etching adhesives, EP and CB, produced the formation of the thinnest hybrid layers.A formação da camada híbrida representa o principal mecanismo de união dos sistemas adesivos odontológicos. Este estudo avaliou a micromorfologia e a espessura da camada híbrida formada por adesivos dentinários. Os adesivos foram avaliados em preparos planificados de dentina na região oclusal de dentes humanos. Os espécimes foram preparados e analisados em MEV sob 2.000 X de magnitude. Os sistemas adesivos mostraram formação de diferentes espessuras de camada híbrida (p < 0,05) e suas médias foram (mim): para o Scotchbond MP Plus (SM), 7,41 ± 1,24; para o Single Bond (SB), 5,55 ± 0,82; para o Etch & Prime 3.0 (EP), 3,86 ± 1,17 e, para o Clearfil SE Bond (CB), 1,22 ± 0,45. Os resultados sugerem que o adesivo convencional (SM) seguido do adesivo de frasco único (SB) mostraram a formação das camadas híbridas com maior espessura, enquanto os adesivos autocondicionantes EP e CB, formaram respectivamente as mais delgadas

Efeitos de agentes dessensibilizantes na obliteração de túbulos dentinários

O objetivo deste estudo foi avaliar as características de obliteração dos túbulos dentinários de três agentes dessensibilizantes: produto a base de oxalato de potássio / Oxa-Gel (OX), produto a base de HEMA e glutaraldeído / Gluma Desensitizer (GD) e produto a base de flúor-fosfato acidulado / Nupro Gel (AF). A região vestibular e cervical de vinte e quatro terceiros molares humanos extraídos foi planificada e polida com lixas de SiC e pastas de diamante para simular superfícies vestibulares dentinárias cervicais com hipersensibilidade. Os dentes foram aleatoriamente divididos em quatro grupos (n=6), de acordo com os seguintes tratamentos superficiais da dentina: G1: sem tratamento; G2: OX; G3: GD; G4: AF. Os espécimes foram fraturados no sentido línguo-vestibular e preparados para microscopia eletrônica de varredura (MEV). OX promoveu oclusão pela deposição de cristais no interior dos túbulos. Enquanto, GL criou uma camada delgada sobre a superfície da dentina, a aplicação do AF produziu a formação de precipitados que ocluíram os túbulos. De acordo com a análise em MEV, todos agentes dessensibilizantes testados foram capazes de obliterar túbulos dentinários.The aim of this study was to evaluate the features of dentinal tubules occlusion following application of three commercially available desensitizing agents: potassium oxalate-based / Oxa-Gel (OX), HEMA and glutaraldehyde-based / Gluma Desensitizer (GD) and acidulated phosphate fluoride-based / Nupro Gel (AF). Buccal cervical areas of twenty-four extracted human third molars were smoothed and wet-polished with SiC papers and diamond pastes, in order to simulate the clinical aspect of hypersensitive dentin cervical surfaces. The teeth were randomly divided into four groups (n=6), according to the dentin surface treatments: G1: untreated; G2: OX; G3: GD; G4: AF. Specimens were fractured in the lingual-buccal direction and prepared for SEM analysis. OX promoted tubule occlusion by crystal-like deposits in the lumen of the tubules. While GL created a thin layer over the dentin surface, AF application produced precipitates that occluded the tubules. According to the SEM analysis, all desensitizing agents were able to occlude the dentinal tubules

Porosity, water sorption and solubility of denture base acrylic resins polymerized conventionally or in microwave

The proper selection of polymerization cycle is important to prevent overheating of the monomer that could cause degradation, porosity and, consequently, deleterious effects on the denture base properties. Objective: This study evaluated the porosity, water sorption and solubility of acrylic resins (Vipi Cril-VC and Vipi Wave-VW) after conventional or microwave polymerization cycles. Material and Methods: Specimens (n = 10) were made and cured: 1-WB = 65°C during 90 min + boiling during 90 min (VC cycle - control group); 2-M25 = 10 min at 270 W + 5 min at 0 W + 10 min at 360 W (VW cycle); 3-M3 = 3 min at 550 W; and 4-M5 = 5 min at 650 W. Afterward, they were polished and dried in a dessicator until a constant mass was reached. Specimens were then immersed in distilled water at 37°C and weighed regularly until a constant mass was achieved. For porosity, an additional weight was made with the specimen immediately immersed in distilled water. For water sorption and solubility, the specimens were dried again until equilibrium was reached. Data were submitted to 2 way-ANOVA and Tukey HSD (α=0.05). Results: Porosity mean values below 1.52% with no significant difference among groups for both materials were observed. Resins showed water sorption and solubility values without a significant difference. However, there was a significant difference among groups for these both properties (P&lt;0.013). The highest sorption (2.43%) and solubility (0.13%) values were obtained for WB and M3, respectively. Conclusions: The conventional acrylic resin could be polymerized in a microwave since both the materials showed similar performance in the evaluated properties. Sho

EFEITO DA ADIÇÃO DE AGENTES ANTIMICROBIANO/ANTIFÚNGICO SOBRE DUREZA E RUGOSIDADE SUPERFICIAL DE CONDICIONADOR TECIDUAL

O objetivo desse estudo foi determinar o efeito da incorporação de antifúngicos (nistatina- N, miconazol- M ou cetoconazol- K) ou de agente antimicrobiano (diacetato de clorexidina-C) sobre propriedades físicas de um condicionador de tecido (Softone-S). Foi avaliado o padrão de incorporação destas drogas no material S por MEV/EDS. Os grupos avaliados foram: G1 = controle (sem adição de droga); G2 = N-500.000 U; G3 = N-1.000.000 U; G4 = M-125 mg; G5 = M-250 mg; G6 = K-100 mg; G7 = K-200 mg; G8 = C-5% e G9 = C-10% em relação à quantidade total (6 g) de S. As quantidades das drogas (em pó) foram misturadas ao pó de S, sendo o líquido de S posteriormente adicionado à mistura. Amostras (n = 5) foram plastificadas à temperatura ambiente por 10 min. As leituras de dureza (Shore A) e rugosidade (Ra) foram realizadas após imersão das amostras em água destilada a 37°C por 24 h, 7 e 14 dias. Os resultados foram analisados pela análise de variância (2-ANOVA)/ Tukey (α = 0,05). Após todos os períodos avaliados (24 h, 7 e 14 dias), a dureza dos grupos experimentais foi superior (P 0,05) à do G1 (5,83 µm). Após 14 dias, a rugosidade do G5, G8 e G9 foi superior (P < 0,05) (7,93; 9,63 e 10,29 µm, respectivamente) à do G1 (6,92 µm). O material modificado demonstrou morfologia favorável, por meio de MEV/EDS, para liberação intra-bucal das drogas avaliadas. Foram observadas alterações nas propriedades físicas do material modificado, entretantodeve-se avaliar se são clinicamente significantes

A novel acrylic resin palatal device contaminated with Candida albicans biofilm for denture stomatitis induction in Wistar rats

Denture stomatitis is the most frequent oral lesion in removable prosthesis wearers, with high recurrence rates and a complex treatment.&nbsp;Objective:&nbsp;This study describes a protocol to obtain and to contaminate a palatal device with Candida albicans biofilm that could be used for an animal model of denture stomatitis.&nbsp;Methodology: Acrylic resin devices (N=41) were obtained from impressions of the palates of Wistar rats with individual trays and polyether. The efficacy of microwave irradiation (MW), ultraviolet light (UV), or ultrasonic bath (US) was assessed by colony viability and spectrophotometric analyses (n=5) in order to select the most appropriate method for sterilizing the devices. Then, different devices (n=5) were contaminated with C. albicans and evaluated by CFU/mL determination, scanning electron microscopy, and laser confocal microscopy. Device stabilization was assessed with either autopolymerizing acrylic resins or a self-adhesive resin cement (n=2). The spectrophotometric data were analyzed by one-way ANOVA followed by the Tukey’s HSD post-hoc test (α=0.05).&nbsp;Results: MW was the only method capable of sterilizing the devices, and the contamination protocol developed a mature and viable C. albicans biofilm (~1.2 x 106 CFU/mL). The self-adhesive resin cement was the best stabilization material.&nbsp;Conclusions: This acrylic resin palatal device was designed to be similar to the clinical situation of contaminated prostheses, with easy manufacturing and handling, effective stabilization, and satisfactory contamination. Thus, the acrylic device can be a valuable tool in the development of denture stomatitis in rats

Morphology and thickness of the diffusion of resin through demineralized or unconditioned dentinal matrix

The formation of a hybrid layer is the main bonding mechanism of current dentin-bonding systems. This study evaluated the morphology and thickness of the resin-infiltrated dentinal layer after the application of adhesive systems. The dentin-bonding agents were evaluated on flat dentinal preparations confected on the occlusal surfaces of human teeth. The test specimens were prepared and inspected under scanning electron microscopy at a magnification of X 2,000. The adhesive systems were responsible for different hybrid layer thicknesses (p < 0.05), and the mean values were: for Scotchbond MP Plus (SM), 7.41 ± 1.24mum; for Single Bond (SB), 5.55 ± 0.82mum; for Etch & Prime 3.0 (EP), 3.86 ± 1.17mum; and for Clearfil SE Bond (CB), 1.22 ± 0.45mum. The results suggest that the conventional three-step adhesive system (SM) was responsible for the thickest hybrid layer, followed by the one-bottle adhesive (SB). The self-etching adhesives, EP and CB, produced the formation of the thinnest hybrid layers