Effects of silane application on luting fiber posts using self-adhesive resin cement.

PURPOSE: To evaluate the effects of different glass-fiber post surface treatments on the bond strength to root dentin. MATERIALS AND METHODS: Fifty bovine incisors were used in this study. After removing the crowns, the teeth were endodontically treated. The roots were randomly divided into five groups according to post surface treatment. The groups were as follows: CO (Control) - no treatment; G1 - RelyX Ceramic Primer (silane) only; G2 - silane and Solobond M; G3 - silane and Scotchbond Adhesive; G4 - silane and Excite. For post cementation, RelyX Unicem was used according to the manufacturer's recommendation and the roots were stored in a light-proof container with 100% relative humidity for 24 h. The specimens were transversally sectioned. Subsequently, the cervical, middle, and apical regions of the root were positioned in a push-out device and tested at 0.5 mm/min using a universal testing machine (Instron). The data were statistically analyzed with two-way ANOVA and Tukey's post-hoc test. The fractured specimens were then observed under a stereoscopic loupe at 60X magnification. RESULTS: No significant difference in bond strength was found among the groups that received a silane or silane plus an adhesive system (p > 0.05). However, the CO (no silane) showed the lowest bond strength. Regarding G1, G2, G3, and G4, the cervical region of the root canal attained better bond strengths than did the middle or apical regions. The most frequent failure mode occurred at the cement/dentin interface. CONCLUSION: Silane application may be necessary to improve the adhesion of fiber posts luted with the self-adhesive resin cement evaluated here. The application of an adhesive layer between the fiber post and resin cement did not have any influence on the bond strength when the silane coupling was previously used.

Effect of finishing and polishing techniques on the surface roughness of a nanoparticle composite resin

To evaluate the surface roughness of the resin Filtek Z350 (3M ESPE) after different finishing and polishing techniques. Methods: Sixty specimens of 7x2 mm were made and distributed in 6 groups (n=10), according to the technique employed: G1 (control) – polyester strip – no finishing or polishing; G2- multi-blade burs; G3- diamond burs 3195F and 3195FF; G4- Diamond ProDiscs (FGM); G5- Sof-Lex Discs (3M ESPE); G6- Robinson bristle brushes with pumice paste for20 s and felt disc with 2-4 ìm diamond paste for 30 s. The specimens were stored in artificial saliva at 37°C for 7 days. After the finishing and polishing techniques, surface roughness (Ra, ìm) was measured using Surf-Corder profilometer SE 1700. Data were subjected to one-way ANOVA andTukey’s test at 5% significance level. Results: G3 presented the highest surface roughness meanvalue (0.61). G5 presented the lowest surface roughness mean value (0.15), but it was not significantly different from G1, G4 and G6. Conclusions: According to the obtained results, Z350 composite resin presented the lowest surface roughness when finishing and polishing systems were used (Sof-lex and Diamond Pro discs and Robinson bristle brush with pumice plus Diamond®felt disc with Diamond Excel® paste). The use of diamond burs (G3) resulted in the highest composite surface roughness. There was no significantly different between G1, G4, G5 and G6.

Bond strength of dental adhesive systems irradiated with ionizing radiation.

PURPOSE: The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems. MATERIALS AND METHODS: One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm2). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photo-activated for 20 s. Each group was subdivided into 4 subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey's test and Dunnett's test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05). RESULTS: No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001). CONCLUSION: The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength.

Rugosidade produzida em restauradores resinosos pela escovaçäo mecânica com escovas dentais complexas / Produced roughness on resin filling by mechanical brushing with complex tooth brushes

Este trabalho avaliou a rugosidade superficial dos restauradores Z100 e Compoglass produzida pela escovaçäo com as escovas dentais Oral-B 30, Alcance Reach Control, Kolinos Doctor Flexível e Colgate Total. Cada grupo de escova foi dividido em dois subgrupos, conforme associaçäo com água e dentifrício. Os corpos-de-prova foram escovadas mecanicamente, e a superfície foi analisada com auxílio de um rugosímetro. O Compoglass escovado com dentifrício e escova Oral-B 30 apresentou a maior média numérica de rugosidade, seguida por Alcance Reach Control e Holynos Doctor Flexível, que näo diferiram entre si estatisticamente, e Colgate Total, com a menor média estatística. Para Z100, näo houve diferença entre a rugosidade produzida após escovaçäo com dentifrício e os diferentes tipos de escovas dentais. O mesmo näo aconteceu com o Compoglass, que também apresentou maior valor de rugosidade superficial em relaçäo ao Z100