Effects of modifying the bonding protocol on the shear bond strength of metallic and ceramic orthodontic brackets.

The purpose of this study was to evaluate the in vitro shear bond strength and failure site of metallic and ceramic orthodontic brackets with modified bonding protocols. Sixty bovine mandibular incisors with similar anatomy were selected and divided into six groups (n = 10). In the first protocol, metallic and ceramic brackets were bonded according to the manufacturers' directions (controls); in the second protocol, the step of photocuring with the primer agent was eliminated; and in the third protocol, the primer agent was applied on the tooth and on the bracket base, followed by application of the composite adhesive on the bracket base, with one-step photocure. The same orthodontic adhesive was used for all groups. Shear bond strengths were measured and adhesive remnant index scores (ARI) were determined after bracket failure. The results demonstrated similar shear bond strengths in the protocols but presented significantly greater values for the metallic groups (two-way ANOVA, P < 0.05). ARI scores were compared with chi-square tests, and the ceramic brackets had significantly greater ARI scores compared to the metallic brackets. Based on these results, the manufacturer's bonding protocol can be modified to save clinical time without compromising adhesion of the brackets.

Evaluation of the force generated by gradual deflection of 0.016-inch NiTi and stainless steel orthodontic wires in self-ligating metallic and esthetic brackets.

BACKGROUND: The purpose of this study was to evaluate the deflection forces of 0.016-inch Nitinol and stainless steel orthodontic wires, in association to different self-ligating brackets. MATERIAL AND METHODS: Specimens were mounted in a clinical simulation model and evaluated in a Universal Testing Machine (INSTRON 3342), using a 10N load cell and ISO 15,841, as a protocol. Eight of these models were prepared, each one for the bonding of each set of self-ligating accessories to be tested: Damon Q, Damon Clear (Ormco), In-Ovation R, In-Ovation C (GAC), BioQuick, QuickClear (Forestadent), SmartClip and Clarity SL (3M). Data were subjected to One-way ANOVA, followed by Tukey tests (P<0.05). RESULTS: Elastic deflection results showed that the deactivation forces increased with increase in wire deflection in the different brackets evaluated. For the different combinations, Clarity SL generated the greatest force and Damon Clear presented the lowest force when compared to the other brackets in all alloys and deflections. BioQuick and QuicKlear were those with the most similar behavior with each other. CONCLUSIONS: Strength values increased with gradual increase in wire deflection in all evaluated brackets. Clarity SL generated the greatest and Damon Clear the lowest force when compared to the other brackets in all alloys and deflections tested. Key words:Brackets, orthodontic wires, deflection.

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen.

OBJECTIVE: This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. MATERIAL AND METHODS: Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-µm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. RESULTS: The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). CONCLUSIONS: Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.

The effects of TiO2 nanotubes on bond strength and radiopacity of a self-adhesive resin cement in self-curing mode / Os efeitos de nanotubos de TiO2 na resistência de união e radiopacidade de um cimento resinoso auto-adesivo no modo auto-polimerizável

Objective: The aim of this in vitro study w as t o analyze the influence of the titanium dioxide nanotubes i n a self-cure mode polymerization of a dual resin luting agent through push out bond strength and radiopacity tests. Material and Methods: After mixed with a commercial du al self-adhesive resin cement, three concentrations o f tit anium dioxide nanotubes (0.3, 0.6, and 0.9% by weight) we re analyzed in self-curing mode. T he bond strength to bovine root dentin and fi berglass posts was assessed with the push out bond str ength t est and was evaluated in three thirds (cervical, middle and apical) (n=10), followed by failure mode analysis (SEM), and the ISO standard 9917-2 was followed for radiopacity test (n=10). Data were statistically analyzed by one-way ANOVA test, followed by Tukey's test (α=0.05). Results: Reinforced self-adhesive resin cement with 0.6% titanium dioxide nanotubes showed significant difference compared to the control gr oup for push out test (p=0.00158). The modified groups did not s how significant difference among thirds (p=0.782). Radiopacity sh owed higher value for group w ith 0.9% titanium dioxide nanotubes in comparison w ith control group (p<0.001). Conclusion: The addition of titanium dioxide nanotubes to a self-adhesive resin cement increased the bond strength to dentin and radiopacity values in the self-cure polymerization mode (AU)

Objetivo: O objetivo deste estudo in vitro foi analisar a influência de nanotubos de dióxido de titânio na polimerização química de um agente cimentante resinoso dual através de testes de resistência à união e radiopacidade. Material e Métodos: Após misturado com um cimento resinoso auto-adesivo comercial, três concentrações de nanotubos de dióxido de titânio (0,3, 0,6 e 0,9% em peso) foram analisadas. A resistência da união para a dentina da raiz bovina e os pinos de fibra de vidro foi avaliada pelo teste de push-out e avaliada em três terços (cervical, médio e apical) (n = 10), seguido pelo análise de modo de falha (MEV) e a norma ISO 9917-2 foi seguido para teste de radiopacidade (n = 10). Os dados foram analisados estatisticamente pelo teste ANOVA um fator seguido do teste de Tukey (α = 0,05). Resultados: O cimento resinoso auto-adesivo reforçado com nanotubos de dióxido de titânio a 0,6% mostrou diferença significativa em comparação com o grupo controle para teste de push-out (p=0,00158). Os grupos modificados não mostraram diferença significativa entre os terços (p=0,782). A radiopacidade mostrou maior valor para o grupo com nanotubos de dióxido de titânio 0,9% em comparação com o grupo controle (p<0,001). Conclusão: A adição de nanotubos de dióxido de titânio a um cimento resinoso auto-adesivo aumentou a os valores de resistência de união à dentina e radiopacidade no modo de polimerização química do agente cimentante (AU)

Teleducation about Cleft Lip and Palate: An Interdisciplinary Approach in the Promotion of Health.

Introduction The Young Doctor Project (YDP) uses Telehealth and Interactive Teleducation instruments to promote the integration of different areas of health and to build knowledge. This methodology can also foster public awareness on various issues related to health. In this context, the objective of this study was to emphasize cleft lip and palate (CLP), which is one of the most common birth defects in Brazil. Objective The study aimed to apply a model of education regarding CLP, based on the dynamics of the YDP, and to evaluate the participants' knowledge acquired after participating in the YDP. Methods The participants were 41 students, 13 to 15 years of age and at the eight- and ninth-grade levels in a private elementary school in Bauru (Brazil). To analyze the performance of the participants, a questionnaire was administered before and after the completion of the training program. The training program was structured in three steps using: (1) interactive teleducation classes, (2) a cybertutor, and (3) practical activities. Results There was a statistically significant difference between the pre- and postparticipation questionnaire results. The improved performance of participants is evidenced by the increase in the rate of correct answers on all issues. Conclusion The YDP on CLP was applied in the school setting following the three steps recommended by the project, and, after the implementation of the training program, there was a significant increase in participants' knowledge of CLP. The YDP on CLP proved an effective tool in promoting health education.

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen

Abstract Objective This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and Methods Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.

Marginal adaptation in proximal cavities restored with composites and other materials / Adaptação marginal em cavidades proximais com compósitos e outros materiais

Objective: To evaluate the marginal adaptation, in enamel (E) and dentin (D), of composite resin (CR) associated with flowable resin composite (flow), bulk fill flowable base (bulk) and resin modified glass ionomer cement (RMGIC) in slot cavities. Material and Methods: The study was conducted after approval (Protocol No. 21148413.4.0000.5417) from Ethics Committee. Forty extracted human molar teeth were randomly assigned in eight experimental groups: E-CR, E-BULK, E-FLOW, E-RMGIC, D-CR, D-BULK, D-FLOW, D-RMGIC. The occlusal surface was planned, two slot cavities with standard sizes (depth: 2.0 mm, height: 2.5 mm, width: 2.0 mm) were created on a machine for making cavities. The teeth were restored and after 24h subjected to 2000 cyclic loading and sectioned for analysis of marginal adaptation by scanning electron microscopy (SEM). The micrographs were analyzed with the Image J program to measure the size of marginal gaps. The data were transformed into percentages (%GAPS = LG ÷ LM × 100) and analyzed by 2-way ANOVA followed by the post hoc Tukey test (α=0.05). Results: There was a significant difference between different treatments (p0.05). Conclusions: It was concluded that restorations with flowable composite resin and bulk fill liners exhibit the same behavior, but the RMGIC liner increased marginal gap (AU)

Objetivo: Avaliar a adaptação marginal, em esmalte (E) e dentina (D), de restaurações com resina composta (RC) associada a resina composta fluida (flow), resina bulk fill (bulk) e cimento de ionômero modificado por resina (CIVMR) em cavidades tipo slot. Materiais e Métodos: O estudo foi realizado após aprovação no Comitê de Ética e Pesquisa (Protocolo no. 21148413.4.0000.5417). Quarenta molares humanos foram aleatoriamente distribuídos em oito grupos experimentais: E-RC, E-BULK, E-FLOW, E-CIVMR, D-RC, D-BULK, D-FLOW, D-CIVMR. A superfície oclusal foi planificada e duas cavidades tipo slot com tamanhos padronizados (profundidade: 2,0 mm, altura: 2,5 mm, largura: 2,0 mm) foram realizadas em uma máquina para confecção de cavidades. Os dentes foram restaurados e, após 24h, submetidos a 2000 ciclos mecânicos e foram seccionados para análise da adaptação marginal em microscopia eletrônica de varredura (MEV). As micrografias foram analisadas através do programa Image J para medir as fendas marginais. Os dados foram transformados em porcentagens (%fendas = largura da fenda / largura da margem x 100) e analisados através do teste ANOVA-2 critérios seguido do teste de Tukey (α=0,05). Resultados: Houve diferença significante entre os diferentes tratamentos (p0,05). Conclusões: Concluiu-se que as restaurações com base de resina flow e bulk fill exibiram o mesmo comportamento, mas a base de CIVMR aumentou a fenda marginal. (AU)

Multidisciplinary approach to the establishment and maintenance of an esthetic smile: a 9-year follow-up case report.

In addition to providing functionality to patients, contemporary dentistry strives for esthetic excellence. Patients with anterior impairments, such as shape, size, and position alterations, have compromised smile harmony. A multidisciplinary orthodontic-operative dentistry approach has improved the treatment of these patients, since the use of orthodontic appliances in association with direct composite restorations can solve many esthetic problems. Although this treatment strategy is rather widespread, professional skills are necessary for the correct reproduction of the main features of teeth. Moreover, treatment success is directly related to its longevity. With the aid of a 9-year follow-up case report, a simple direct technique associated with an orthodontic treatment for restoring the esthetic appearance of an impaired smile, with good short- and long-term outcomes, based on minimal but essential esthetic repair interventions is discussed. Such coordinated treatment proved to be effective for the establishment and maintenance of an esthetic and pleasant smile.

Conservative approach for a clinical resolution of enamel white spot lesions.

Enamel white spot lesions in anterior teeth that compromise esthetics are common. Microabrasion is indicated, since it affects enamel superficially. An acid-abrasive slurry with 37% phosphoric acid with pumice was used on the enamel for a controlled time period. Home bleaching with hydrogen peroxide was then used, further improving the final result. The method is safe, easy, and conservative and provides good esthetic results.

Curing depth of a silorane-based resin composite

Introduction: The silorane-based resin appears aiming to minimize the effects of polymerization shrinkage, but other properties must be studied. Objective: To evaluate the polymerization depth of two composites with different organic matrix. Material and methods: 80 cylindrical specimens were prepared using a metallic matrix, with three layers (top, middle and bottom), 1 mm high and 5 mm in diameter. The specimens were divided into eight groups (n = 10) according to the composite resins: Filtek P90 (3M/ESPE); Filtek Z250 (3M/ESPE), light-cured with a LED device with different irradiance and times (600mW/cm2 x 40s, 1000mW/cm2 x 40s, 1000mW/cm2 x 20s; 1400mW/cm2 x 20s). The irradiance was controlled by placing plastic rings coupled to the device's tip. Immediately after polymerization, the specimens' layers were separated and five Knoop microhardness readings (initial hardness) were performed on each one of the four layers (0, 1, 2, and 3 mm). After 7 day storage in water at 37ºC, new readings were performed (final microhardness). The data were analyzed by four-way ANOVA (resin, energy density, depth and time) and Tukey test (α = 0.05). Results: The microhardness decreased with the depth increasing both in the initial and 7 day readings. The hardness increased with the highest power densities. The resin P90 had lower hardness values. Conclusion: The silorane-based resin showed Knoop microhardness values significant smaller than those of methacrylate-based resin in almost all evaluated parameters. However, both presented similar behaviors in relation to the curing depth.

Teleducation about Cleft Lip and Palate: An Interdisciplinary Approach in the Promotion of Health

Introduction The Young Doctor Project (YDP) uses Telehealth and Interactive Teleducation instruments to promote the integration of different areas of health and to build knowledge. This methodology can also foster public awareness on various issues related to health. In this context, the objective of this study was to emphasize cleft lip and palate (CLP), which is one of the most common birth defects in Brazil. Objective The study aimed to apply a model of education regarding CLP, based on the dynamics of the YDP, and to evaluate the participants' knowledge acquired after participating in the YDP. Methods The participants were 41 students, 13 to 15 years of age and at the eight- and ninth-grade levels in a private elementary school in Bauru (Brazil). To analyze the performance of the participants, a questionnaire was administered before and after the completion of the training program. The training program was structured in three steps using: (1) interactive teleducation classes, (2) a cybertutor, and (3) practical activities. Results There was a statistically significant difference between the pre- and postparticipation questionnaire results. The improved performance of participants is evidenced by the increase in the rate of correct answers on all issues. Conclusion The YDP on CLP was applied in the school setting following the three steps recommended by the project, and, after the implementation of the training program, there was a significant increase in participants' knowledge of CLP. The YDP on CLP proved an effective tool in promoting health education. .

Water sorption and solubility of different calcium hydroxide cements.

OBJECTIVES: Calcium hydroxide cements have been largely used in deep cavities due to their abilities to stimulate dentin formation. However, their resistance can be relatively low and their solubility relatively high, in many instances. This study evaluated water sorption and solubility of different calcium hydroxide cements, in order to show alterations that may reduce their effectiveness. MATERIAL AND METHODS: Five discs (20 mm in diameter and 1.5 mm thick) of three different materials (Biocal, Dycal and Hidro C) were prepared with the aid of a ring-shaped metallic matrix. After being stored at 37 degrees C for 24 h, the discs were weighed on a precision weight scale, dehydrated and weighed again. Immediately after weighing, discs were stored for a week in 50 mL of distilled water at 37 degrees C and, then, weighed again, dehydrated and submitted to a new weighing. The loss of soluble material and its water sorption was obtained from the difference between the initial and the final dry mass of each disc, after 1 week of immersion in water. Data were analyzed for significant differences by two-way ANOVA and Tukey's test (p<0.05). RESULTS: Mean water sorption values (g) +/- standard deviation and percentage (%), for each evaluated cement, were: Biocal (0.006 +/- 0.001 / 2.15); Dycal (0.016 +/- 0.004 / 5.49); and Hidro C (0.025 +/- 0.003 / 8.27). Mean solubility values (g) +/- standard deviation and percentage (%), for each evaluated cement, were: Biocal (0.002 +/- 0.001 / 0.72); Dycal (0.013 +/- 0.004 / 4.21); and Hidro C (0.023 +/- 0.004 / 7.65). CONCLUSIONS: Biocal absorbed less water and was less soluble than the other evaluated cements; Hidro C exhibited the highest water sorption and solubility values; and there were significant differences among all evaluated experimental groups.

Wear and surface roughness of bovine enamel submitted to bleaching.

The present study evaluated surface roughness and wear of bovine enamel following three different bleaching techniques and simulated brushing. Initial surface roughness (Ra) was evaluated and teeth were randomly divided into 4 groups (n = 10): Group 1, control; Group 2, 35% hydrogen peroxide (HP) activated by a hybrid light; Group 3, 35% HP activated by a halogen light; and Group 4, 16% carbamide peroxide. After bleaching, surface roughness was measured and teeth were subjected to 100,000 cycles of simulated brushing. After brushing, the final roughness and wear was determined. Data were statistically analyzed by ANOVA and Tukey test (P < 0.05). There were no significant differences among groups comparing initial and postbleaching roughness. After brushing, significant differences were found between the control and experimental groups. Group 4 showed a significant increase in roughness values compared with Group 2. The control group showed significantly less wear than other groups. Bleaching techniques promoted increased roughness and wear of bovine enamel, when submitted to simulated brushing. Tooth enamel after bleaching can present a larger alteration in the amount of roughness due to brushing.

The effects of occlusal loading on the margins of cervical restorations.

BACKGROUND: Researchers have proposed the restoration of abfraction lesions, but limited information is available about the effects of occlusal loading on the margins of such restorations. Because abfraction is a well-recognized problem, the authors conducted a study to assess the effects of occlusal loading on the margins of cervical restorations. METHODS: The authors prepared 40 wedge-shaped cavities in extracted premolars and restored them with a resin-based composite. They subjected specimens to occlusal loading (150 newtons, 10(6) cycles) on the buccal cusp, on the central fossa or on the lingual cusp, and they stored the control group specimens in deionized water. The authors used fluorescein to delimit marginal defects and evaluated the defects by using laser scanning confocal microscopy. RESULTS: Results of chi2 and Kruskal-Wallis tests (P < .05) showed that specimens subjected to occlusal loading had a higher percentage of marginal gaps (53.3 percent) than did the control specimens (10.0 percent). There were no differences between groups in marginal defect formation or in defect location, length or width. CONCLUSIONS: Occlusal loading led to a significant increase in gap formation at the margins of cervical resin-based composite restorations. CLINICAL IMPLICATIONS: The clinician cannot underestimate the effects of occlusal loading when restoring teeth with cervical wedge-shaped lesions. If occlusal loading is the main factor contributing to lesion formation, the clinician should identify and treat it before placing the restoration or otherwise run the risk that the restorative treatment will fail because of marginal gap formation.

Glass ionomer cements and their role in the restoration of non-carious cervical lesions.

Glass ionomer based materials are clinically popular in several areas of restorative dentistry, but restoration of cervical lesions has proven particularly successful. Various etiologies, conformations, locations and structural characteristics make non-carious cervical lesions more challenging to adhesive restorative procedures and marginal seal in the long run. Due to their characteristics, glass ionomer cements (GICs) have precise indication for these cases. Moreover, the use of a GIC base underneath composite resin, the so-called 'sandwich' or mixed technique, allows associating the good characteristics of composite resins and GICs, and has been considered quite useful in the restoration of non-carious cervical defects. The aim of this paper is to critically review the literature and discuss peculiar features of GICs regarding their role in the restoration of non-carious cervical lesions.

Effect of sealants in the composite surface roughness after tooth brushing / Efeito de selantes na rugosidade de resinas compostas após a escovação simulada

This in vitro study evaluated the influence of 4 surface sealers on the surface roughness of composite resins. Fifty specimens were divided into 10 groups, as follows: G1. (Control 1) Concept resin; G2. Concept + Fortify; G3. Concept + Biscover; G4. Concept + Lasting Touch; G5. Concept + Fill Glaze; G6. (Control 2) Esthet X; G7. Esthet X + Fortify; G8. Esthet X + Biscover; G9. Esthet X + Lasting Touch; G10. Esthet X + Fill Glaze. Specimens (15mm in length, 4 mm in depth and 5 mm in width) were made using a matrix and were stored in distilled water at 37ºC for 24 hours. After storage, specimens were polished using 320, 600 abrasive SiC paper under running water and the initial roughness was measured using a perfilometer. Surface sealers were applied and a new measurement of roughness was made. Specimens were submitted to 100,000 cycles of abrasive dentifrice brushing followed by another surface roughness measurement. Qualitative analysis was made by using SEM. Results were submitted to 3-way modified ANOVA (p<0.05) and Tukey's test. Results: Surface sealant provided smoother surfaces for both tested composite resins (G2=0.0727, G3=0.0147, G4=0.0307, G5=0.0253, G7=0.0173, G8=0.0333, G9=0.0480, G10=0,0480). After the abrasion test, the control group presented lower roughness surface (G1=0.0600, G6=0.1007). No statistical difference were found between Fortify (G2=0.0740, G7=0.0673) and Biscover (G7=0.0440). Lasting Touch presented rougher surfaces in relation to the other groups (G4= 0.1253, G9=0.0980), followed by Fill Glaze (G5=0.0933, G10= 0.0847). The application of surface sealant did not provide roughness optimization after tooth brushing simulation for the 2 composite resins tested.

Este estudo avaliou, in vitro, a influência de 4 selantes de superfície na rugosidade de duas resinas compostas. Cinqüenta espécimes foram confeccionados e divididos em 10 grupos com 5 espécimes cada, em função da combinação entre resina composta e selante de superfície, sendo: G1. Controle Concept; G2. Concept + Fortify; G3. Concept + Biscover; G4. Concept + Lasting Touch; G5. Concept + Fill Glaze; G6. Controle Esthet X; G7. Esthet X + Fortify; G8. Esthet X + Biscover; G9. Esthet X + Lasting Touch; G10. Esthet X + Fill Glaze. Os espécimes (15mm X 4 mm X 5 mm) foram confeccionados e armazenados em água destilada à 37ºC por 24 horas. Após este período, os espécimes foram planificados com lixas de granulometria 320, 600 e a rugosidade inicial foi aferida. Aplicaram-se os selantes de superfície e uma nova aferição da rugosidade superficial foi realizada. Os espécimes foram submetidos a 100.000 ciclos de escovação, seguido de nova mensuração da rugosidade. Os resultados foram submetidos aos testes ANOVA a 3 critérios e Tukey. A aplicação do selante de superfície diminuiu a rugosidade superficial das resinas compostas testadas (G2=0,0727, G3=0,0147, G4=0,0307, G5=0,0253, G6=0,0960, G7=0,0173, G8=0,0333, G9=0,0480). Nenhuma diferença estatística foi encontrada entre o grupo Fortify (G2=0,0740, G7=0,0673) e Biscover (G7=0,0440). Os maiores valores de rugosidade foram apresentados pelo grupo Lasting Touch (G4= 0,1253, G9=0,0980), seguido do Fill Glaze (G5=0,0933, G10= 0,0847). A aplicação do selante de superfície não otimizou a rugosidade das duas resinas compostas testadas após o teste de abrasão simulada.

Volumetric polymerization shrinkage of contemporary composite resins.

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (á = 0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87+/-0.01) and Definite (1.89+/-0.01) shrank significantly less than the other composite resins. SureFil (2.01+/-0.06), Filtek Z250 (1.99+/-0.03), and Fill Magic (2.02+/-0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

Avaliação da resistência de união de reparos de resina composta, utilizando-se diferentes tratamentos de superfície / Evaluation of microtensile bond strength of composite resin repair using different surface treatments

Objetivo: Avaliar a resistência de união de reparos de restaurações em resina composta utilizando-se diferentes tratamentos de superfície. Materiais e Métodos: Foram utilizadas 180 amostras de resina composta Tetric Ceram® (Ivoclar/Vivadent), distribuídas em 9 grupos (n=20/grupo). No momento do reparo, cada grupo recebeu tratamento de superfície específico: ácido fosfórico a 37% (Ivoclar/Vivadent); ácido hidrofluorídrico a 10% (Dentsply) ou microjateamento com partículas de óxido de alumínio de 50μm (Micro Jato VH®). Em seguida, aplicou-se o sistema adesivo Heliobond® (Ivoclar/Vivadent), associado ou não ao agente silanizadorMonobond-S® (Ivoclar/Vivadent). Foram também confeccionados espécimes que não sofreram nenhum tipo de reparo (grupo controle). Os espécimes ficaram armazenados em água deionizada por 18 meses. Posteriormente cada amostra foi submetida ao teste de resistência de união à microtração em máquina de ensaio universal (EMIC DL500BF), a uma velocidade de 0,5 mm/minuto. Os dados obtidos em MPa foram submetidos a avaliação da normalidade da variável microtração por meio do teste Kolmogorov-Smirnov. Considerando quea variável não apresentou distribuição normal (p<0,001) foram realizados os testes de Kruskal-Wallis e Mann-Whitney. O valor de p considerado foi menor que 0,05, exceto, quando se utilizou da correção de Bonferroni(p<0,00138). Resultados: Os espécimes do grupo controle apresentaram resistência à tração estatisticamente superior em relação aos demais grupos. O emprego do ácido fosfórico e posterior inserção do sistema adesivo apresentou resultados estatisticamente significante em relação aos demais grupos reparados. Conclusões: A resistência coesiva da resina composta foi superior às outras técnicas de reparo utilizadas. O emprego do ácido fosfórico e posterior inserção do sistema adesivo demonstrou ser o tratamento ideal para o reparo derestaurações em resina composta.

Técnica mista: clareamento dentário e microabrasão: relato de caso clínico / Mixed technique: tooth bleaching and microabrasion: clinical xase report

O objetivo deste trabalho é apresentar a resolução estética do caso clínico de um paciente com dentes escuros e manchas de fluorose, em que foi realizado o clareamento dentário em consultório, associado à microabrasão do esmalte. O clareamento foi efetuado nos dentes de ambas as arcadas, exceto nos molares. Após condicionamento do esmalte, o agente clareador à base de peróxido de hidrogênio a 35 por cento (Lase Peroxide Sensy, DMC Equipamentos Ltda.) foi aplicado e ativado duas vezes de 3 minutos com aparelho de luz híbrida de LED/laser de diodo terapêutico (Whitening Lase II, DMC Equipamentos Ltda.). Esse processo foi repetido cinco vezes, na mesma sessão, seguido de polimento, laserterapia e aplicação do gel dessensibilizante por 4 minutos. Em uma segunda sessão de clareamento, os caninos e pré-molares receberam mais duas aplicações do gel clareador ativado com luz híbrida. Ao final do procedimento, o paciente ainda apresentava manchas brancas nos dentes superiores, sendo realizada, no final da sessão, a microabrasão do esmalte. Ao final do tratamento, pode-se constatar resultado estético satisfatório alcançado por meio do clareamento dos dentes e remoção das manchas hipocalcificadas.

The objective of this paper was to present the esthetics resolution of a clinical case of a patient with discolored teeth and fluorosis which performed in-office tooth whitening plus enamel microabrasion. Bleaching was done in the teeth of both arches, except the molars. After etching enamel with phosphoric acid at 37% for 15 seconds, the whitening agent with 35% of hydrogen peroxide (Lase Peroxide Sensy, DMC Equipamentos Ltda) was applied twice and activated for three minutes with a hybrid LED/Laser light appliance (Whitening Lase II, DMC Equipamentos Ltda). This process was repeated five times in the same session, followed by polishing, laser therapy and application of desensitizing gel for 4 minutes. In a second session of bleaching, canines and premolars received two more applications of the whitening gel activated with hybrid light. At the end of the procedure, the patient still had white spots on the upper teeth, being held at the end of the session, the microabrasion of the enamel. At the end of treatment, one can see satisfactory final result achieved by means of teeth whitening and removal of hipocalcified stains

Effect of a metal primer on the bond strength of the resin-metal interface.

To evaluate the effect of different surface treatments on shear bond strength between a metallic alloy (Co-Cr-Mo - Remanium CD) and a resin cement (Rely X TM) and to evaluate the mode of fracture after testing, forty couples of metallic-alloy disks were melted, regularized, polished, submitted to four thermal cycles (Vacuum, 960ºC, 8 minutes) and randomly separated into four groups. Each group received a different type of treatment: Group PSP: Polished with sandpaper 600; Group PCP: Polished with sandpaper 600 and application of the metal primer Alloy Primer (Kuraray); Group JSP: Sandblasted with 100µm aluminum oxide; Group JCP: Sandblasted with 100mm aluminum oxide and treated with a metal Primer. The groups were cemented and stored in distilled water at 37ºC for 36 hours and submitted to the shear bond strength test. The mean and standard deviation (in Kgf/cm²) obtained for each group was: PSP 4.0/0.4; PCP 88.9/33.6; JSP 163.2/27.6; JCP 144.5/54.0. After the statistical analysis the authors concluded that: the highest values were obtained for the sandblasted groups (JSP, JCP), regardless of the primer application; the Alloy Primer increased the retention between the Rely X cement and the polished surface of the Co-Cr-Mo alloy, yet its bond strength was not greater than that obtained with sandblasting; all specimens showed adhesive failures in the tested interface.