Este estudo comparou a reproducao de detalhes da superficie e estabilidade dimensional de modelos de gesso obtidos a partir de diferentes alginatos (Cavex ColorChange, Hydrogum 5, Jeltrate Plus) e com diferentes tempos de armazenagem (1, 3, e 5 dias) para modelos obtidos de moldes que foram preenchidos imediatamente sem tempo de armazenagem. Os moldes foram preparados sobre matriz contendo linha de 50 μm (norma ISO 1563) realizado sob pressao com moldeira de metal perfurada. Os moldes foram removidos 2 minutos apos a perda de consis - tencia pegajosa e preenchidos imediatamente ou armazenados em frascos fechados com temperatura (37°C) e umidade relativa (100%) controladas por 1, 3 ou 5 dias. Os moldes foram preenchidos com gesso dental (Durone IV). A reproducao de detalhes da superficie e a estabilidade dimensional foram avaliadas usando microscopia optica na linha 50 μm com 25 mm de comprimento, de acordo com a norma ISO 1563. Os resultados de estabilidade dimensional (%) foram submetidos a analise de variancia. A linha de 50 μm (norma ISO 1563) foi completamente reproduzida por todos os alginatos, independentemente do tempo de armazenagem. Nao houve diferenca estatisticamente significa - tiva nos valores medios de estabilidade de modelos de gesso obtidos de moldes de diferentes alginatos com diferentes tempos de armazenagem (p = 0.989). Em conclusao, o armazenamento do molde durante cinco dias antes do preenchimento nao alterou a reproducao de detalhes da superficie ou estabilidade dimensional dos alginatos examinadas neste estudo.

This study compared the surface detail reproduction and dimensional accuracy of stone models obtained from molds prepared using different alginate impression materials (Cavex ColorChange, Hydrogum 5, or Jeltrate Plus) and with different storage times (1, 3, and 5 days) to models from molds that were filled immediately with no storage time. The molds were prepared over a matrix containing 50-μm line, (ISO 1563 standard) under pressure with a perforated metal tray. The molds were removed 2 minutes after loss of sticky consistency and either filled immediately or stored in closed jars at 100% relative humidity and 37°C for 1, 3, or 5 days. The molds were filled with dental plaster (Durone IV). Surface detail reproduction and dimensional accuracy were evaluated using optical microscopy on the 50-μm wide line, which was 25 mm in length, according to ISO 1563 standard. The dimensional accuracy results (%) were subjected to analysis of variance. The 50-μm wide line (ISO 1563 standard) was completely reproduced by all alginate impression materials regardless of the storage time. There was no statistically significant difference in the mean dimensional accuracy values of stone models made from molds composed of different alginate impression materials and with different storage times (p = 0.989). In conclusion, storing the mold for five days prior to filling did not change the surface detail reproduction or dimensional accuracy of the alginates examined in this study.

OBJECTIVES: The aim of this study was to investigate the bond strength of ceramic restorations luted using a self-adhesive resin cement (RelyX Unicem, 3M ESPE) under different dentin conditions. MATERIAL AND METHODS: In the experimental groups, ceramic restorations were luted to bovine incisors with RelyX Unicem under the following conditions: [Dry dentin]: surface was dried using air stream for 15 s; [Moist dentin]: excess dentin moisture was removed with absorbent paper; [Bonding agent]: Clearfil SE Bond (Kuraray) self-etching adhesive system was previously applied to dentin. In the Control group, cementation was done using an etch-and-rinse adhesive (Excite DSC) and Variolink II resin cement (Ivoclar Vivadent). Photoactivation of the resin cements was performed with UltraLume LED 5 unit (Ultradent). The restorations (n=5 per group) were sectioned into beams and microtensile testing was carried out. Data were subjected to ANOVA and Tukey's test (p<0.05). Failure modes were classifed under Scanning Electron Microscopic (SEM) (x120 magnifcation). RESULTS: The bond strength was dependent on the moisture status of the dentin. Bond strength in the "dry dentin group" was signifcantly lower than that of all other groups, which showed similar results. A predominance of mixed failures was detected for the control group, while a predominance of adhesive failures was observed for the "bonding agent" and "dry dentin" groups. The "moist dentin" group presented predominantly cohesive failures within the luting material. The previous application of a self-etching adhesive showed no signifcant effect. CONCLUSIONS: Only excess dentin moisture should be removed for the cementation of ceramic restorations with self-adhesive resin cements.