Effect of luting cement thickness on the bond strength of glass fiber posts to dentin.

The objective of this study was to evaluate the effect of cement thickness and luting cement type on the push-out bond strength of glass fiber posts (GFPs) to root dentin. Sixty human maxillary root-filled canines or premolars with single straight roots were randomly divided into 6 groups (n = 10) according to the GFP configuration (conventional or relined with composite resin) and the cement used (RelyX U200, Ketac Cem, or Allcem Core). After endodontic treatment and GFP cementation, all of the roots were sectioned perpendicular to their long axis to obtain 1.0-mm-thick slices (n = 6 per group), which were mounted on a universal testing machine and submitted to a push-out test. The data (n = 45 to 51 specimens per group because of pretest failures) were analyzed by means of 2-way analysis of variance (ANOVA) and Tukey tests (α = 0.05). The type of failure was determined under a stereomicroscope, and representative specimens were observed with scanning electron microscopy. Significant interactions between the cements and GFP configurations were detected in the coronal and apical thirds (P < 0.05; 2-way ANOVA). For the coronal third, both RelyX U200 cement groups exhibited the greatest push-out bond strengths but were not significantly different from the Allcem Core relined group. For the middle third, no statistically significant interactions were observed between the cements and GFP configurations (P = 0.232; 2-way ANOVA). Adhesive failure between the dentin and cement layer was the most frequently observed failure mode. As expected, because of the composite resin added to relined GFPs, the cement layer was thinner in those groups. The type of cement used played an important role in the push-out bond strength.

Morphology of autogenous bone graft and castor oil polyurethane in the infraorbital rim of rabbits: a comparative study / Estudo morfológico comparativo do enxerto ósseo autógeno e polímero de mamona em rebordo infra-orbitário de coelhos

PURPOSE: Morphological study comparing castor oil polyurethane and autogenous bone graft to repair bone defect in zygomatic bone of rabbits. METHODS: Twenty-four adult, male New Zealand rabbits were randomly distributed between two groups of twelve. Bone defects of 5mm in diameter were cut through the zygomatic bone and filled with polyurethane discs in the experimental group or autogenous bone harvested from the tibia in the control group. Animals were sacrificed after 30, 60 or 90 days, and the zygomatic bones were macro- and microscopically analyzed. Student's, Fisher's, chi-squared and McNemar's tests were used for statistical analysis. RESULTS: Both the castor oil polyurethane and the autograft adapted well to the defect, with no need for fixation. Fibrous connective tissue encapsulated the polyurethane, but no inflammation or giant cell reaction was observed. Acidophilic and basophilic areas were observed inside the micropores of the polyurethane, suggesting cell nuclei. After 90 days, bone repair with a lamellar pattern of organization was observed in the control group. CONCLUSION: The castor oil polyurethane was biocompatible and did not cause inflammation. It may be considered an alternative to fill bone defects.

OBJETIVO: Estudo morfológico comparativo do implante de poliuretana de mamona e enxerto ósseo autógeno em defeito ósseo padrão em osso zigomático de coelhos. MÉTODOS: Vinte e quatro coelhos Nova Zelândia, machos, adultos, foram distribuídos aleatoriamente em dois grupos de 12. Defeitos de 5mm de diâmetro, perenes, foram confeccionados em osso zigomático e preenchidos com discos pré-fabricados de poliuretana no grupo experimento ou osso autógeno extraído da tíbia no grupo controle. Os animais foram sacrificados após 30, 60 e 90 dias e as peças anatômicas foram avaliadas macro e microscopicamente. Foram utilizados os testes de Student, Fisher,qui-quadrado e McNemar para a análise estatística dos resultados. RESULTADOS: A poliuretana e o osso autógeno se adaptaram ao defeito sem necessidade de fixação. Houve formação de tecido conjuntivo fibroso envolvendo a poliuretana, sem reação inflamatória ou presença de células gigantes. Verificaram-se áreas acidófilas e basófilas nos poros do material implantado, sugestivas de núcleos celulares. No grupo controle, observou-se aos 90 dias o reparo ósseo de padrão lamelar clássico. CONCLUSÃO: A poliuretana de mamona foi biocompatível e não causou reação inflamatória deletéria. Pode ser uma alternativa para o preenchimento de defeitos ósseos.

Morphology of autogenous bone graft and castor oil polyurethane in the infraorbital rim of rabbits: a comparative study.

PURPOSE: Morphological study comparing castor oil polyurethane and autogenous bone graft to repair bone defect in zygomatic bone of rabbits. METHODS: Twenty-four adult, male New Zealand rabbits were randomly distributed between two groups of twelve. Bone defects of 5mm in diameter were cut through the zygomatic bone and filled with polyurethane discs in the experimental group or autogenous bone harvested from the tibia in the control group. Animals were sacrificed after 30, 60 or 90 days, and the zygomatic bones were macro- and microscopically analyzed. Student's, Fisher's, chi-squared and McNemar's tests were used for statistical analysis. RESULTS: Both the castor oil polyurethane and the autograft adapted well to the defect, with no need for fixation. Fibrous connective tissue encapsulated the polyurethane, but no inflammation or giant cell reaction was observed. Acidophilic and basophilic areas were observed inside the micropores of the polyurethane, suggesting cell nuclei. After 90 days, bone repair with a lamellar pattern of organization was observed in the control group. CONCLUSION: The castor oil polyurethane was biocompatible and did not cause inflammation. It may be considered an alternative to fill bone defects.