Salivary, acidic and enzymatic degradation of resin composite subjected to different finishing and polishing systems.

PURPOSE: To evaluate the effect of different finishing and polishing systems on the surface roughness of a resin composite subjected to simulated saliva-, acid-, and enzyme-induced degradation. METHODS: 160 specimens (n= 40) were fabricated with Filtek Z350 XT nanofilled composite and analyzed for average surface roughness (Ra). The specimens were finished and polished using: AD - Al2O3-impreginated rubberized discs (medium, fine, and superfine grit, Sof-Lex); SD - silicon carbide and Al2O3-impregnated rubberized discs (coarse, medium and fine grit, Jiffy,); MB - 12- and 30-multiblade burs. The control group (CT) (n= 40) comprised specimens with a Mylar-strip-created surface. Specimens from each group were immersed in 1 mL of one of the degradation methods (n= 10): artificial saliva (ArS: pH 6.75), cariogenic challenge (CaC: pH 4.3), erosive challenge (ErC: 0.05M citric acid, pH 2.3) or enzymatic challenge (EzC: artificial saliva with 700 µg/mL of albumin, pH 6.75). The immersion period simulated a time frame of 180 days. Ra measurements were also performed at the post-polishing and post-degradation time points. The data were evaluated by three-way ANOVA for repeated measures and the Tukey tests. RESULTS: There was significant interaction between the finishing/polishing system and the degradation method (P= 0.001). AD presented the greatest smoothness, followed by SD. After degradation, CT, AD and SD groups became significantly rougher, but not the MB group, which presented no difference in roughness before or after degradation. CT and AD groups showed greater roughness in CaC, ErC and EzC than in ArS. The SD group showed no difference in roughness when the specimens were polished with CaC, EzC or ArS, but those treated with ErC had greater roughness. In the MB group, the lower roughness values were found after using CaC and EzC, while the higher values were found using ErC or ArS. CLINICAL SIGNIFICANCE: As far as degradation resistance of nanofilled composite to hydrolysis, bacterial and dietary acids and enzymatic reactions is concerned, restorations that had been finished and polished with Al2O3-impregnated discs had the smoothest surfaces.

Effect of simplified or multi-step polishing techniques on roughness and color stability of resin composites.

PURPOSE: To evaluate the impact of simplified or multi-step polishing techniques on the roughness, color, and susceptibility to staining of different resin composites. METHODS: Discs (Ø6 mm x 2 mm) were obtained from different resin composites [nanofilled (Z350XT), suprananofilled (Estelite Omega), and nanohybrid (Forma)]. The specimens (n= 15) were submitted to a simplified protocol using abrasive discs (Sof-Lex) and spiral discs (Diacomp Plus Twist), or a multi-step protocol using abrasive discs (Sof-Lex), abrasive points (Jiffy), silicon carbide brush and felt disc with diamond pastes (Diamond Polish). The specimens were evaluated initially for roughness (Ra) and color (CIEL*a*b*, CIEDE 2000), after completing the polishing protocol, and after exposure to a coffee solution (pH= 5.01). The data were analyzed according to the variables, using generalized linear models, and the Friedman, Nemenyi, Kruskal-Wallis, Dunn, and Mann-Whitney tests (α= 0.05). RESULTS: The nanohybrid resin composite showed an increase in Ra following use of both polishing methods (P= 0.038). Both techniques promoted an increase in L* values after polishing; however, the general color changes (ΔEab and ΔE00) were greater after the multi-step polishing (P< 0.05). After immersion in coffee, the multi-step polished groups of the nanohybrid and suprananofilled resin composite showed higher L* values than the simplified polishing groups (P= 0.023), and the nanofilled resin composite showed higher ΔEab and ΔE00 values than the other resin composites, regardless of the polishing technique (P< 0.05). CLINICAL SIGNIFICANCE: The choice of the resin composite had a greater effect on roughness, color stability and susceptibility to staining than the polishing technique. However, luminosity after coffee staining was higher with the multi-step polishing technique.

Biomechanical behavior of weakened roots restored with custom-made post-and-cores of glass fiber and polyetheretherketone.

PURPOSE: To evaluate the influence of post type and mechanical aging on compression force resistance, fracture pattern, and stress distribution in weakened roots. MATERIALS AND METHODS: Bovine roots were endodontically treated and widened-and randomly divided into 8 groups (n = 10) according to post type (prefabricated glass fiber post and customized anatomic glass fiber post, milled glass fiber post-and-core, and milled polyetheretherketone post-and-core) and mechanical aging (without and with mechanical aging). Three hundred thousand cycles of mechanical fatigue were performed and compression force resistance (N) was analyzed by two-way ANOVA and Tukey test (α = 0.05). Fracture patterns were reported and stress distribution was analyzed by finite elements analysis. RESULTS: There was a significant effect of post type (p = 0.032) and mechanical aging (p = 0.009), but no double interaction (p = 0.879). Higher values were recorded in the milled glass fiber and polyetheretherketone post-and-core groups compared to the prefabricated glass fiber post groups, and no significant difference was found among anatomic glass fiber post groups and other groups. Reparable fractures were predominant in the milled glass fiber and polyetheretherketone post-and-core groups. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution. CONCLUSIONS: Post type and mechanical aging influence the compression force resistance and fracture pattern of weakened roots. Milled glass fiber and polyetheretherketone post-and-cores exhibited higher compression force resistance and more reparable fractures compared to prefabricated glass fiber posts. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.

Dental implant-abutment fracture resistance and wear induced by single-unit screw-retained CAD components fabricated by four CAM methods after mechanical cycling.

STATEMENT OF PROBLEM: Computer-aided design and computer-aided manufacturing (CAD-CAM) methodologies allow the fabrication of custom dental implant abutments with a variety of materials and techniques. Studies on the mechanical strength of such components and the wear induced at their coupling interface during mechanical cycling are sparse. PURPOSE: The purpose of this in vitro study was to measure the wear patterns at the hexagonal platform of dental implants induced by the installation and mechanical cycling of custom abutments fabricated by using 4 different CAD-CAM methods and to determine the compressive static resistance of the implant-abutment combinations. MATERIAL AND METHODS: A CAD software program was used to design a custom abutment for a single-unit screw-retained external hexagon dental implant crown. The same design file was used to manufacture with 4 CAM methods (N=40): milling and sintering of zirconium dioxide (ZO), cobalt-chromium (Co-Cr) sintered by selective laser melting (SLM), fully sintered machined Co-Cr alloy (MM), and machined and sintered agglutinated Co-Cr alloy powder (AM). Prefabricated titanium abutments were used as a control (TI). Each abutment was installed onto a dental implant (4.1×11 mm), and the specimens were mechanically aged (1 million cycles, 2 Hz, 100N, 37 °C). After mechanical cycling, the hexagonal connection of the dental implants was examined with a scanning electron microscope (SEM), and unused dental implants (NI) were examined as a control (n=10). The images were analyzed with a software program to quantify the areas that showed wear. The implant-abutment combinations were reassembled and submitted to a compression test (1mm/min) with a universal testing machine. The data obtained were submitted to 1-way ANOVA (α=.05). RESULTS: The mean ±standard deviation fracture load (N) of the specimens of each group were 1005 ±187 (ZO), 1074 ±123 (SLM), 1033 ±109 (MM), 1019 ±149 (AM), and 923 ±129 (TI). These values were statistically similar (P=.213). The mean ±standard deviation wear of the implants in squared-pixels were 1.1 ±0.38×105 (ZO), 2.0 ±0.29×105 (SLM), 1.0 ±0.38×105 (MM), 1.1 ±0.27×105 (AM), 1.1 ±0.33×105 (TI), and 0.51 ±0.29×105 (NI). The results indicated that, although significantly higher than those in in the control group (NI), the wear values found in the groups TI, ZO, MM, and AM were significantly lower than in the SLM group (P<.001). CONCLUSIONS: The CAD-CAM abutments presented the same mechanical fracture load and wear measurements as the TI group, except for the SLM material, which showed increased wear. The failure mode from the load bearing test was the fracture of the abutments for the ZO group. The implants permanently deformed or fractured for the metal abutment groups.

Influence of fluoride-releasing materials in the inhibition of enamel and dentin demineralization around restorations / Influência de materiais liberadores de flúor na inibição da desmineralização do esmalte e da dentina ao redor de restaurações

Objective: The aim was to evaluate the influence of fluoride-releasing restorative materials in enamel and dentin microhardness. Material and Methods: 40 blocks (5x5x3 mm) from cervical third of human molars received a cavity preparation between the enamel and dentin, and the restorations were subjected to in vitro caries model. Specimens were randomly restored with (n=10): conventional glass ionomer cement (Ketac Cem, 3M ESPE); polyacid-modified composite resin (Ionoseal, VOCO); resin-modified glass ionomer cement (Ionofast, Biodinâmica); or microhybrid composite resin (Filtek Z250, 3M ESPE). The specimens were sectioned longitudinally and enamel and dentin Knoop microhardness were determined at different distances from the restorative material (100, 200 and 300 µm) and depth of surface (20, 40 and 60 µm). The data were submitted to three-way repeated measures ANOVA and Tukey ́s test ( α =0.05). Results: For enamel, the double interactions between material x distance and material x depth were statistically significant. In all depths and distances, the highest values of enamel microhardness were observed for Ketac Cem. In dentin, the materials differed statistically from each other, and Ionoseal obtained higher microhardness values than those found in Ionofast. Conclusion: Conventional glass ionomer cement is more effective in preventing enamel demineralization around restoration followed by the polyacid-modified composite resin. In dentin, the polyacid-modified composite resin obtained better performance than resin-modified glass ionomer cement. (AU)

Objetivo: O objetivo foi avaliar a influência de materiais restauradores liberadores de flúor na microdureza do esmalte e da dentina. Material e Métodos: 40 blocos (5x5x3 mm) do terço cervical de molares humanos receberam preparo cavitário entre esmalte e dentina, e após a restauração foram submetidas a um modelo in vitro de cárie. As amostras foram restauradas aleatoriamente com (n=10): cimento de ionômero de vidro convencional (Ketac Cem, 3M ESPE); resina composta modificada por poliácidos (Ionoseal, VOCO); cimento de ionômero de vidro modificado por resina (Ionofast, Biodinâmica); ou resina composta microhíbrida (Filtek Z250, 3M ESPE). As amostras foram seccionadas longitudinalmente e a microdureza Knoop de esmalte e dentina foi determinada em diferentes distâncias do material restaurador (100, 200 e 300 µm) e profundidade de superfície (20, 40 e 60 µm). Os dados foram submetidos à ANOVA para medidas repetidas de três fatores e teste de Tukey (α =0,05). Resultados: Para o esmalte, as duplas interações entre material x distância e material x profundidade foram estatisticamente significativas. Em todas as profundidades e distâncias, os maiores valores de microdureza do esmalte foram observados para o Ketac Cem. Na dentina, Ionoseal obteve valores de microdureza superiores aos encontrados no Ionofast. Conclusão:O cimento de ionômero de vidro convencional é mais eficaz na prevenção da desmineralização do esmalte ao redor da restauração, seguido pela resina composta modificada por poliácidos. Na dentina, a resina composta modificada por poliácidos obteve melhor desempenho que o cimento de ionômero de vidro modificado por resina. (AU)

Low- and high-viscosity bulk-fill resin composites / Resinas compostas bulk-fill de baixa e alta viscosidade

ABSTRACT The aim of this study was to compare low- and high-viscosity bulk-fill composites for Knoop microhardness (KHN), microtensile bond strength (MTBS) to dentin in occlusal cavities, and fracture strength (FS) in molars with mesialocclusal- distal restoration. Disk-shaped samples with different thicknesses (2 or 4 mm) of low-viscosity (SDR Flow, Dentsply) and high-viscosity bulk-fill composites (Filtek BulkFill, 3M ESPE; and Tetric-N Ceram Bulk Fill, Ivoclar Vivadent) were prepared for top and bottom KHN analysis (n=10). MTBS to dentin and fracture pattern was evaluated in human molars with occlusal cavities restored with (n=10): conventional nanocomposite (Z350XT, 3M ESPE), low-viscosity (Filtek Bulk-fill Flow, 3M ESPE) or high-viscosity bulk-fill composites (Filtek BulkFill). The FS and fracture pattern of human molar with mesial-occlusal-distal restorations submitted or not to thermomechanical cycling were investigated (n=10) using: intact tooth (control), and restoration based on conventional microhybrid composite (Z250, 3M ESPE), low-viscosity (SDR Flow) or high-viscosity bulk-fill composites (Filtek BulkFill). The data were submitted to split-plot ANOVA (KHN), one-way ANOVA (MTBS), two-way ANOVA (FS) followed by Tukey's test (α=0.05). For KHN, there was no significant difference for the resin composites between the top and bottom. For MTBS, no significant differences among the materials were detected; however, the low-viscosity composite presented lower frequency of adhesive failures. For FS, there was no significant difference between composites and intact tooth regardless of thermomechanical cycling. Low- and high-viscosity bulk-fill composites have comparable microhardness and microtensile bond strength when used in occlusal restorations. Likewise, the bulk-fill composites present similar fracture strength in molars with mesio-occlusal-distal restorations.

RESUMO O objetivo deste estudo foi comparar resinas compostas bulk- -fill de baixa e alta viscosidade quanto à microdureza Knoop (KHN), resistência de união a microtração (MTBS) em cavidades oclusais e carga à fratura (FS) em molares com restauração mesio-oclusal-distal. Amostras em forma de disco com diferentes espessuras (2 ou 4 mm) de resinas bulk-fill de baixa viscosidade (SDR Flow, Dentsply) e alta viscosidade (Filtek BulkFill, 3M ESPE; e Tetric-N Ceram Bulk Fill, Ivoclar Vivadent) foram obtidas para análise de KHN no topo e na base (n = 10). A MTBS em dentina e o padrão de fratura foram avaliados em molares humanos com cavidades oclusais restauradas com (n = 10): resina composta nanoparticulada convencional (Z350XT, 3M ESPE), resinas bulk-fill de baixa viscosidade (Filtek Bulk-fill Flow, 3M ESPE) ou alta viscosidade (Filtek BulkFill). Foram investigados a FS e o padrão de fratura de molares humanos em restaurações mesial-ocluso-distais sub metidas ou não à ciclagem termomecânica (n = 10), sendo: dente íntegro (controle), e restaurações baseadas em resina composta microhíbrida convencional (Z250, 3M ESPE); resinas bulk-fill de baixa viscosidade (SDR Flow) ou alta viscosidade (Filtek BulkFill). Os dados foram submetidos a split-plot ANOVA (KHN), one-way ANOVA (MTBS), two-way ANOVA (FS) seguidos do teste de Tukey (α = 0,05). Para KHN, não houve diferença significativa entre o topo e a base para as resinas compostas. Para MTBS, não foram detectadas diferenças significativas entre os materiais; entretanto, a resina bulk-fill de baixa viscosidade apresentou menor frequência de falhas adesivas. Para FS, não houve diferença significativa entre os materiais e o dente íntegro, independentemente da ciclagem termomecânica. As resinas bulk-fill de baixa e alta viscosidade têm microdureza e resistência à microtração comparáveis quando usados em restaurações oclusais. Da mesma forma, as resinas bulk-fill apresentam resistência à fratura semelhante em molares com restaurações mesio-oclusal-distais.

Effect of cavosurface angle beveling on the exposure angle of enamel prisms in different cavity sizes.

The quality of the micromechanical retention between the enamel prisms exposed through acid etching and adhesive system can be influenced by the relationship between the angle of the exposed enamel prisms and the external surface/restorative material. Therefore, the aim of the present study was to determine the influence of the enamel cavosurface beveling in different cavity sizes on the angle relation between enamel prisms and the restorative material. For this research, 30 human permanent molars were used and divided into three groups according the isthmus aperture of class I cavities (1/4, 1/3, and 1/2 of the intercuspal distance). Cavosurface angle beveling was performed in each tooth buccal or palatal/lingual side, and a resin composite restoration was placed. Each restored tooth was sectioned in buccal/palatal direction followed by analysis in scanning electron microscope. Means of the angles observed between enamel prisms and the restorative material were registered and statistically analyzed by Kruskal-Wallis test. Results showed higher mean angle values for beveled groups when comparing with the values observed in the unbeveled margins (p < .05) regardless of the isthmus aperture, being 1/4 (beveled = 48.36°; unbeveled = 20.71°), 1/3 (beveled = 39.75°; unbeveled = 29.15°), and 1/2 (beveled = 37.02°; unbeveled = 26.34°). It was also observed that in some unbeveled cavities, there were the presence of laterally exposed enamel prisms (0°), mainly in more conservative cavities. It was concluded that the presence of higher angles values occurred in the samples with beveled margins, without presence of laterally exposed enamel prisms.

Effect of sucralfate against hydrochloric acid-induced dental erosion.

OBJECTIVE: Devising effective measures for the prevention of hydrochloric acid (HCl)-induced erosion is of great significance. This is even more important in dentine, in which products have limited diffusion. Therefore, agents that can bind to proteins forming an acid-resistant gel-like coat, such as sucralfate, may stand out as a promising alternative. This study investigated the protective effect of sucralfate suspensions against HCl-induced dental erosion. MATERIALS AND METHODS: In the first experiment, hydroxyapatite (HAp) crystals were pre-treated with a commercial sucralfate suspension (CoSS, pH 5.9), a stannous-containing sodium fluoride solution (NaF/SnCl2 pH 4.5), two prepared sucralfate suspensions (PrSS, pH 5.9 and 4.5), or deionized water (DI, control). HAp dissolution was measured using a pH-stat system. In a subsequent experiment, embedded/polished enamel and root dentine slabs were allocated into five groups to be treated with one of the tested substances prior to and during erosion-remineralization cycles (HCl-2 min + artificial saliva 60 min, two times per day, 5 days). Surface loss was assessed profilometrically. Data were analyzed by ANOVA and Tukey's tests. RESULTS: HAp dissolution was as follows: NaF/SnCl2 < CoSS < PrSS/pH 4.5, while PrSS/pH 5.9 = DI and both did not differ from CoSS and PrSS/pH 4.5. In enamel, surface loss did not differ between CoSS and PrSS/pH 4.5, with both having lower surface loss than PrSS/pH 5.9 and DI and NaF/SnCl2 differing only from DI. In root dentine, surface loss was as follows: CoSS < PrSS/pH 5.9 < (NaF/SnCl2 = DI), while PrSS/pH 4.5 = CoSS = PrSS/pH 5.9. CONCLUSION: Sucralfate suspension provided anti-erosive protection to HCl-induced erosion. CLINICAL RELEVANCE: Sucralfate may protect teeth against erosion caused by gastric acid.

Oval Versus Circular-Shaped Root Canals: Bond Strength Reached with Varying Post Techniques.

The aim of this study was to compare the bond strength (BS) of glass fiber posts (GFP) luted to oval and circular-shaped root canals rehabilitated using varying post techniques, at different intraradicular levels. Ninety 16-mm-long roots of human mandibular premolars, classified either as having oval or circular-shaped canals, were endodontically treated and prepared for restoration using one of three different post techniques (n=15): 1) single GFP; 2) resin-relined GFP; 3) main GFP associated with accessory posts. GFPs were luted with a dual polymerizing resin cement (RelyX ARC) after the canal had been treated with a 3-step etch-and-rinse adhesive system (Adper Scothbond Multipurpose). The samples were sectioned into three 1-mm-thick sections, which were differentiated by the root level (cervical, middle and apical) and tested for push-out BS. Assessment of failure mode was made under a stereomicroscope. Data were analyzed using repeated measures three-way ANOVA and Tukey's test. The root canal cross-section had a significant influence on BS (p<0.001), with the lowest values being observed in oval-shaped canals. The post technique also significantly affected the BS (p=0.018), with the resin-relined GFPs providing the highest BS values in both oval and circular-shaped canals. Irrespective of the cross-section of the root canal and post technique, there was no significant difference in BS in the cervical, middle and apical third of the root canal (p=0.084). In oval-shaped canals, the BS to intraradicular dentin at cervical, middle or apical level could be increased when the GFPs posts were relined.

Oval versus circular-shaped root canals: bond strength reached with varying post techniques

Abstract The aim of this study was to compare the bond strength (BS) of glass fiber posts (GFP) luted to oval and circular-shaped root canals rehabilitated using varying post techniques, at different intraradicular levels. Ninety 16-mm-long roots of human mandibular premolars, classified either as having oval or circular-shaped canals, were endodontically treated and prepared for restoration using one of three different post techniques (n=15): 1) single GFP; 2) resin-relined GFP; 3) main GFP associated with accessory posts. GFPs were luted with a dual polymerizing resin cement (RelyX ARC) after the canal had been treated with a 3-step etch-and-rinse adhesive system (Adper Scothbond Multipurpose). The samples were sectioned into three 1-mm-thick sections, which were differentiated by the root level (cervical, middle and apical) and tested for push-out BS. Assessment of failure mode was made under a stereomicroscope. Data were analyzed using repeated measures three-way ANOVA and Tukey's test. The root canal cross-section had a significant influence on BS (p<0.001), with the lowest values being observed in oval-shaped canals. The post technique also significantly affected the BS (p=0.018), with the resin-relined GFPs providing the highest BS values in both oval and circular-shaped canals. Irrespective of the cross-section of the root canal and post technique, there was no significant difference in BS in the cervical, middle and apical third of the root canal (p=0.084). In oval-shaped canals, the BS to intraradicular dentin at cervical, middle or apical level could be increased when the GFPs posts were relined.

Resumo O objetivo deste estudo foi comparar a resistência de união (RU) de pinos de fibra de vidro (PFV), cimentados a condutos com secção transversal ovalada ou circular reabilitados com diferentes técnicas de restauração com PFVs, em função do nível intrarradicular. Noventa raízes de pré-molares inferiores humanos, com 16 mm de altura, classificadas como possuindo canais ovais ou circulares, foram tratadas endodonticamente e preparadas para serem reabilitadas com uma das três técnicas de restauração com PFVs (n=15): 1) PFV único, 2) PFV reembasado com resina composta, e 3) PFV principal associado a pinos acessórios. Os PFVs foram cimentados com um agente resinoso de polimerização dupla (RelyX ARC), após o canal ter sido tratado com um sistema adesivo de condicionamento total de três passos (Adper Scothbond Multiuso). As amostras foram seccionadas em três fatias de 1 mm de espessura, de acordo com o nível da raiz (cervical, médio e apical)e foram submetidas ao teste de RU por push-out. A análise do modo de falha foi realizada com auxílio de um estereomicroscópio. Os dados foram analisados utilizando-se a ANOVA a três critérios para medidas repetidas e o teste de Tukey. A secção do conduto apresentou influência na RU (p<0,001), com os menores valores sendo observados nos condutos ovalados. A técnica de restauração com PFVs afetou significativamente a RU (p=0,018), tendo o PFV reembasado proporcionado os maiores valores de RU, tanto em condutos ovais quanto circulares. Independentemente da secção transversal do conduto radicular e da técnica de restauração com PFV, não houve diferença significativa na RU nos terços cervical, médio e apical (p=0,084). Nos canais de secção transversal ovalada, a RU à dentina intrarradicular nos níveis cervical, médio ou apical aumentou com o emprego de PFVs reembasados.

Stresses generated by two zygomatic implant placement techniques associated with conventional inclined anterior implants.

PURPOSE: To make a comparative evaluation, by means of the finite element method, of the stress generated on supporting tissues and prosthetic system components, using zygomatic implants with the exteriorized and extramaxillary techniques, and different placement positions, associated either with inclined anterior implants, or those without inclination. MATERIALS AND METHODS: Eight (8) tridimensional models were created to represent the clinical situations being researched, using the dataset of scanned images of an edentulous model. The implants and prosthetic components were photographed on millimeter paper and inserted into Rhinoceros 3D modeling computer software. From the measurements made on the image, the virtual models were made. The application force was distributed on the occlusal surface of the working side of the left maxillary first molar, first and second premolars, and incisal regions of the central incisor, simulating the occlusal load during mastication, in a total of 150 N. RESULTS: The extramaxillary technique presented considerable variation in increased tension on the prosthesis screws and bone tissue. In the exteriorized technique, the highest tension values occurred in the region of the ridge, and the lowest, on the zygomatic process; the absence of cantilever reduced the stress on bone tissue in almost all regions. CONCLUSION: The exteriorized technique was shown to be more favorable to the distribution of stresses on the micro-unit screws and bone tissue, with the model with zygomatic implant placed in the region of the first molar and inclined anterior implant presenting the best results.

Evaluation of satisfaction of individuals rehabilitated with zygomatic implants as regards anesthetic and sedative procedure: A prospective cohort study.

PURPOSE: To evaluate the satisfaction of individuals with atrophic maxilla, rehabilitated with fixed dental prostheses, anchored on zygomatic implants, with variables being the anesthetic procedure: general anesthesia, or local with sedation. MATERIALS AND METHODS: By means of the clinical record charts from the Training Course in Advanced Hospital Surgeries for Implant Dentists conducted at the Campinas-SP unit of the São Leopoldo Mandic School of Dentistry, 30 individuals were randomly selected. They had zygomatic implant placement surgeries performed, and were rehabilitated with fixed implant supported complete dentures, between the years 2005 and 2011. One group of 15 individuals underwent surgery in hospital, under general anesthesia. The other 15 were treated in the post-graduation clinic at the School of Dentistry, under local anesthesia and sedation. RESULTS: From the emotional point of view, the Wilcoxon test revealed that irrespective of the anesthesia procedure used, at the beginning of treatment, the emotional condition of individuals differed from that verified after conclusion of the treatment (p < 0.0001). CONCLUSION: There was no difference between the two groups as regards the anesthetic procedure. General satisfaction was high; there was emotional improvement after conclusion of the treatment, thus improving the quality of life.

Dental bleaching with ozone: effects on color and enamel microhardness / Clareamento dental com ozônio: efeitos na cor e na microdureza do esmalte

The aim of this in vitro study was to evaluate the effects of dentalbleaching with ozone (O3) on color change and enamelmicrohardness. Enamel blocks (3 x 3 x 3mm) were randomlydistributed for treatments (n=10). Color change (ΔE) and Knoopmicrohardness of the enamel blocks were evaluated before andafter the following treatments: C – deionized water (control); HP– 37.5% hydrogen peroxide (Pola Office+/ SDI); PLA – placebogel; O3– ozone; and O2– oxygen. Four 8-minute applicationswere used for HP and PLA, and one 19-minute application for O3and O2.One-way ANOVA revealed that ΔE was not significantlyinfluenced by the treatment (p = 0.112). For the treatments withHP, PLA, O3 and O2, ΔE was greater than 3.3. The paired t testshowed significant decrease in microhardness after treatments (p< 0.001) but no significant difference between treatments(ANOVA; p = 0.313). Dental bleaching treatments with O3, HP,O2and PLA induced enamel color changes that may be clinicallydiscernible, although enamel microhardeness decreased.

O objetivo deste estudo in vitro foi avaliar os efeitos doclareamento dental com ozônio (O3) quanto à alteração de core microdureza do esmalte. Blocos de esmalte (3 x 3 x 3mm)foram aleatoriamente distribuídos entre os tratamentos(n=10). Alteração de cor (ΔE) e microdureza Knoop foramavaliados antes e após cada um dos seguintes tratamentos: C– água deionizada (controle); PH – peróxido de hidrogênio a37,5% (Pola Office+/ SDI); PLA – gel placebo; O3– ozônio;O2– oxigênio. Quatro aplicações de PH e PLA foramrealizadas por 8 minutos cada e uma aplicação de O3e O2foram realizados por 19 minutos em cada bloco de esmalte.ANOVA a um critério mostrou que os valores de ΔE não foramsignificativamente influenciados pelo tratamento (p = 0,112).Para os tratamentos com PH, PLA, O3 e O2, o ΔE foi maior que3,3. O teste t pareado mostrou diminução significativa dosvalores de microdureza no final do tratamento quandocomparado com o tempo baseline (p < 0,001), mas não houvediferença significativa entre os tratamentos (ANOVA; p =0,313). O tratamento com O3, PH, O2e PLA levou a alteraçãode cor do esmalte clinicamente perceptível, embora tenha sidoobservada diminuição da microdureza do esmalte com arealização dos tratamentos.

Role of lubricants on friction between self-ligating brackets and archwires.

OBJECTIVE: To evaluate the effect of different lubricants on friction between orthodontic brackets and archwires. MATERIALS AND METHODS: Active (Quick, Forestadent) and passive (Damon 3MX, Ormco) self-ligating brackets underwent friction tests in the presence of mucin- and carboxymethylcellulose (CMC)-based artificial saliva, distilled water, and whole human saliva (positive control). Dry friction (no lubricant) was used as the negative control. Bracket/wire samples (0.014 × 0.025 inch, CuNiTi, SDS Ormco) underwent friction tests eight times in a universal testing machine. RESULTS: Two-way analysis of variance showed no significant interaction between bracket type and lubricant (P  =  .324). Friction force obtained with passive self-ligating brackets was lower than that for active brackets (P < .001). Friction observed in the presence of artificial saliva did not differ from that generated under lubrication with natural human saliva, as shown by Tukey test. Higher friction forces were found with the use of distilled water or when the test was performed under dry condition (ie, with no lubricant). CONCLUSION: Lubrication plays a role in friction forces between self-ligating brackets and CuNiTi wires, with mucin- and CMC-based artificial saliva providing a reliable alternative to human natural saliva.

Calcium lactate pre-rinse increased fluoride protection against enamel erosion in a randomized controlled in situ trial.

OBJECTIVES: This in situ trial study was designed to evaluate whether calcium (Ca) pre-rinse would increase the fluoride (F) rinse protection against enamel erosion. METHODS: Fifteen volunteers participated in this split-mouth, 3-phase, crossover design study wearing a palatal appliance containing four sterilized bovine enamel slabs, for 10 days. In the 1st phase, five participants followed protocol A: daily rinse with a Ca lactate (CaL, 150mmol/L, 1min), followed by F (NaF 12mmol/L, 1min). Other five participants followed protocol B: daily rinse only with F, while the remainders followed protocol C: no rinse (negative control). Appliances were removed from the mouth and one side of the palatal appliance was exposed to a daily erosive challenge (0.05M citric acid, 90s); the other side served as control (deionized water - no erosion). In the 2nd phase volunteers were crossed over to other protocol and in the 3rd phase volunteers received the remaining protocol not yet assigned. Specimens were evaluated for surface loss using an optical profilometer. RESULTS: Repeated-measures three-way ANOVA (p=0.009) and Tukey's test showed that CaL pre-rinse followed by NaF rinse significantly decreased surface loss of enamel when performed prior to an erosive challenge in comparison with the condition in which NaF only was used. CONCLUSIONS: Pre-rinse with CaL may increase the protection exerted by NaF against erosive wear.

Counteractive effect of antacid suspensions on intrinsic dental erosion.

This in vitro study aimed to investigate the anti-erosive effect of antacid suspensions applied to enamel after exposure to hydrochloric acid (HCl). Ninety bovine enamel slabs were embedded, flattened, and polished. Reference areas were created and specimens were divided into six groups. They were exposed to 0.01 M HCl (pH 2) for 2 min, followed by immersion for 1 min in one of the following test suspensions: magnesium hydroxide, aluminum hydroxide, magnesium hydroxide/aluminum hydroxide, sodium alginate/sodium bicarbonate/calcium carbonate, or hydrated magnesium aluminate. Artificial saliva was used as a negative control. Specimens were subjected to a total of five cycles of erosion/antacid treatment. Enamel surface loss was measured (in micrometers) by optical profilometry. In addition, baseline and final surface microhardness (SMH) values of enamel were obtained. It was found that antacid suspensions significantly reduced enamel loss, and that similar protection was afforded by all formulations. No differences were observed between the final enamel SMH values among groups. Antacid suspensions counteracted HCl-induced enamel loss, although they were not effective in reducing enamel softening. Mouth rinsing with antacid suspensions after vomiting can potentially represent a promising strategy to counteract enamel loss caused by erosion.