Fracture resistance of maxillary premolars restored with direct and indirect adhesive techniques.

OBJECTIVE: To evaluate the fracture resistance of teeth restored using 2 intracoronal direct and indirect adhesive techniques. METHODS: Forty maxillary premolars were divided randomly into 4 groups of 10: group 1, intact teeth; group 2, mesio-occlusodistal (MOD) cavity preparation associated with endodontic therapy (unrestored); group 3, MOD cavity preparation and restoration with direct composite resin (Z100, 3M ESPE); and group 4, MOD cavity preparation and restoration with indirect ceramic inlay (IPS Empress, Ivoclar-Vivadent). Specimens were subsequently submitted to an axial compression test, using an 8-mm diameter steel ball at a loading speed of 0.5 mm per minute, until their fracture. RESULTS: The average compression force causing cuspal fracture in the 4 experimental groups was group 1, 138.4 kg; group 2, 49.0 kg; group 3, 105.4 kg; and group 4, 82.7 kg. ANOVA analysis and Tukey tests showed that cavity preparation significantly weakened the remaining tooth structure. The fracture resistance of teeth restored using direct composite resin was not significantly different from that of teeth restored with ceramic inlays (p > 0.05). None of the materials tested was able to restore completely the fracture resistance lost during cavity preparation. CONCLUSIONS: Cavity preparation significantly weakens the remaining tooth structure. Direct and indirect intracoronal adhesive restorations can partly restore fracture resistance of teeth weakened by wide cavity preparation.

Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations

O objetivo deste estudo foi determinar o efeito da polimerização gradual, mediante a utilização de aparelhos de Quartzo-Tungustênio-Halógena (QTH) e Arco de Plasma de Xenônio (PAC), no selamento marginal de restaurações classe V em resina composta com margens localizadas em dentina. Setenta e cinco incisivos bovinos receberam preparos de cavidades classe V, na raiz, com o intuito de situar as margens cavitárias em dentina. Os dentes foram divididos em cinco grupos de acordo com o método de fotoativação. As cavidades, depois de condicionadas, foram tratadas com o sistema adesivo Single Bond (3M Dental) e restauradas com a resina composta Z100 (3M Dental) pela técnica incremental. A fotoativação foi realizada para cada grupo como descrito a seguir: Grupo I: PAC pelo método de fotoativação constante: 1600mW/cm2 – 3s; Grupo II: PAC pelo método de fotoativação por passos (800mW/cm2 – 2s, subindo automaticamente para 1600mW/cm2 – 4s); Grupo III: QTH pelo método de fotoativação constante: 400 mW/cm2 – 40s; Grupo IV: QTH pelo método de fotoativação em rampa: 100 a 600 mW/cm2 – 15s, permanecendo a 600mW/cm2 por mais 25s; Grupo V: QTH pelo método de fotoativação por pulso: 200 mW/cm2 – 3s, tempo de espera de 3min.e a seguir 600mW/cm2 – 30s. Os dentes foram armazenados em água destilada a 37ºC por 30 dias e então submetidos à ciclagem térmica, por 500 ciclos à 5 ºC e 55 ºC. Os ápices dos dentes foram selados com resina composta e os dentes foram cobertos com duas camadas de esmalte para unha, antes da sua imersão em fucsina básica a 0,5%. Os dentes foram seccionados e os cortes foram escaneados para avaliação da área infiltrada por corante por um programa de computador (Image Tools). Os cortes foram também visualizados com lupa para a determinação do grau de penetração do corante na interface dente-restauração por escores. Diferenças estatisticamente significantes foram observadas entre os grupos quanto ao grau e à área de penetração de corante (p < 0,05). Os grupos I e II apresentaram valores significantemente mais altos de infiltração e penetração do corante que os grupos III, IV e V. Em conclusão, o uso da fonte de PAC, no modo constante e por passos, resultou em valores significantemente maiores de infiltração marginal quando comparados com a intensidade de luz média emitida pelos aparelhos de QTH. Os métodos de fotoativação por pulso, rampa e continuo com a fonte de QTH resultaram num grau similar de microinfiltração.

Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations.

The aim of this study was to determine the effect of a softstart polymerization method from Quartz-Tungsten-Halogen (QTH) and Plasma Arc (PAC) curing units on microleakage of Class V composite resin restorations with dentin cavosurface margins. Seventy-five bovine incisors received standardized class V cavities in all dentin margins. Teeth were divided into 5 equal groups according to the curing cycle. The cavities were incrementally restored with a composite resin (Single Bond/Z-100, 3M). Light curing was applied as follows: Group I: PAC light continuous-cycle curing at 1600 mW/cm² for 3s; Group II: PAC light step-cycle curing (2s at 800 mW/cm² then 4s at 1600 mW/cm²); Group III: QTH light continuous-cycle curing at 400 mW/cm² for 40s; Group IV: QTH light ramp-cycle curing (from 100 to 600 mW/cm² in 15s followed by 25s at 600 mW/cm²); Group V: QTH light pulse-delay curing (200 mW/cm² for 3s followed by 3 min delay then 600 mW/cm² for 30s). Teeth were stored in distilled water at 37ºC for 30 days and then subjected to thermocycling for 500 cycles at 5 and 55ºC. Root apices were sealed and teeth coated with nail varnish before they were immersed in 0.5% fuchsine red dye solution. Teeth were then sectioned and slices were scanned with a computer scanner to determine the area of dye leakage using a computer program (Image Tools). Images of tooth slices were also visually examined under magnification and dye penetration along the tooth/restoration interface was scored. Significant differences in the degree of dye penetration and leakage were detected between groups (p<.05). Groups I and II had significantly higher values of dye penetration and leakage than groups III, IV and V. In conclusion, the use of PAC light curing in a continuous or step cycle modes resulted in increased microleakage of Class V resin composite restorations compared with medium intensity QTH light curing. Pulse, ramp and continuous-cycle curing modes with QTH light resulted in similar degrees of microleakage.

Clinical evaluation of two types of ceramic inlays and onlays after 6 months / Avaliação clínica de inlays e onlays confeccionadas com dois tipos de cerâmica, após 06 meses

Este trabalho se propôs a avaliar a performance clínica de dois tipos de cerâmica: IPS Empress, Ivoclar-Vivadent - IPS e Duceram Plus, Degussa - D. Foram realizadas 86 restaurações por apenas um operador, sendo 44 IPS e 42 D. Vinte e sete pré-molares e 59 molares, num total de 33 onlays e 53 inlays, foram cimentadas em 35 pacientes de ambos os sexos, com idade média de 35 anos. A cimentação das restaurações foi realizada com cimento resinoso dual (Variolink, Ivoclar-Vivadent) sob isolamento absoluto e avaliadas no baseline e após 06 meses, mediante o critério U.S.P.H.S. modificado, quanto à sensibilidade pulpar, reincidência de cárie, fratura, reprodução de cor, descoloração marginal, integridade marginal e textura superficial. Adicionalmente foram realizadas radiografias e fotografias. No baseline foi obtida a classificação Bravo nos itens sensibilidade pulpar - IPS (2,27%); D (7,14%); reprodução de cor - IPS (2,27%); D (2,38%) e textura superficial - IPS (2,27%); D (11,90%). Após 06 meses foram analisadas as 86 restaurações, nas quais foi constatada a classificação Bravo para os itens reprodução de cor - IPS (6,82%); D (2,38%); textura superficial - IPS (2,27%); D (9,52%); descoloração marginal - IPS (6,82%); D (4,76%) e integridade de superfície- IPS (4,55%); D (7,14%). Os resultados obtidos foram submetidos ao Teste Estatístico de Fisher e McNemar. Não houve diferença estatisticamente significante entre as cerâmicas. Pode-se concluir que os dois tipos de cerâmica demonstraram uma performance clínica satisfatória após 06 meses.

Clinical evaluation of ceramic inlays and onlays made with two systems: a one-year follow-up.

PURPOSE: The aim of this study was to evaluate the clinical performance of ceramic inlays and onlays made with two systems: sintered (Duceram [D], DeguDent) and pressable (IPS Empress [IPS], Ivoclar-Vivadent) after 1 year. MATERIALS AND METHODS: Seventy-four restorations - 37 IPS and 37 D - were cemented in 34 patients. Twenty-four premolars and 50 molars received Class II cavity preparations, totaling 28 onlays and 46 inlays. The restorations were evaluated by two independent investigators at baseline, 6 months, and 1 year, according to modified USPHS criteria. Fisher and McNemar statistical tests were employed to assess the survival rate. RESULTS: After one year, 100% of the restorations were assessed and all the restorations were considered clinically excellent or acceptable. Among the analyzed criteria, only the following received "Bravo" ratings: marginal discoloration: IPS (24.32%), D (13.51%); marginal integrity: IPS (10.81%), D (8.11%); color match: IPS (5.41%), D (5.41%); surface texture: IPS (2.70%), D (10.81%). No "Charlie" or "Delta" scores were given to the restorations. CONCLUSION: Among the analyzed criteria, only marginal discoloration differed statistically significantly from the results of the baseline examination for IPS Empress ceramic restorations (p = 0.008). No significant differences were found between the two ceramics. The two ceramic systems demonstrated excellent clinical performance after a period of 1 year.

Clinical evaluation of two types of ceramic inlays and onlays after 6 months.

The aim of the present study was to evaluate the clinical performance of two types of ceramics: a slurry-powder ceramic (Duceram Plus, Degussa) - D and a hot-pressed leucite-based glass-ceramic (IPS Empress, Ivoclar Vivadent) - IPS. Eighty-six restorations, 44 IPS and 42 D, were made by one operator. A total of 33 onlays and 53 inlays on twenty-seven premolars and 59 molars were cemented in 35 patients of both sexes, mean age 35 years. All restorations were cemented with the dual-resin cement (Variolink, Ivoclar-Vivadent) under rubber dam and were evaluated at the baseline and after six months, using the modified U.S.P.H.S. criteria for postoperative sensitivity, secondary caries, fracture, color match, marginal discoloration, marginal integrity and surface texture. Additionally radiographs and intraoral photographs were carried out. At baseline 86 restorations were analyzed and all of them received Alfa rating, except for the following that received Bravo rating for postoperative sensitivity - IPS (2.27%); D (7.14%); for color match - IPS (2.27%); D (2.38%) and for surface texture - IPS (2.27%); D (11.90%). After 6 months 100% of the restorations were analyzed and the following received Bravo rating: color match - IPS (4.55%) and D (9.52%); surface texture - IPS (2.27%) and D (11.9%); marginal discoloration - IPS (6.82%) and D (4.76%) and marginal integrity - IPS (4.55%) and D (7.14%). The results were submitted to the Fisher and McNemar Statistical Tests. No significant differences were noticed between the two ceramics. Both ceramics demonstrated satisfactory clinical performance after six months.