The effect of light-curing access and different resin cements on apical bond strength of fiber posts.

PURPOSE: This study evaluated the effect of light-curing access on the bond strength of fiber glass posts to the apical area of bovine roots using self-adhesive cement or dual-cured cement with an etch-and-rinse adhesive system. MATERIALS AND METHODS: The root canals of 60 bovine teeth were endodontically treated and filled. A 15-mm-length post space was prepared and roots were randomly divided into three groups, simulating the levels of light-curing access: coronal (C), with 15-mm post space; middle (M), in which the coronal thirds of roots were cut out, leaving a 10-mm post space; and apical (A), in which the coronal and middle thirds of roots were cut out, leaving a 5-mm post space. Fiber glass posts (Reforpost # 3, Angelus) were cemented with RelyX U100 (3M ESPE) or RelyX ARC/Scotchbond Multi Purpose Plus (SBMP) (3M ESPE) (n=10) and light-cured. After 24 hours, the apical thirds of roots were sectioned perpendicularly to the long axis and submitted to a push-out test (0.5 mm/min, 200 N). The Kruskal-Wallis test compared the three levels of light-curing access, and the Mann-Whitney test compared the cements. RESULTS: The bond strength was significantly higher in the groups C (p=0.028) and M (p=0.016) when U100 was used, whereas it was similar for both cements in group A. The bond strengths of posts cemented with ARC/SBMP were significantly higher in group A compared to group C (p=0.031). CONCLUSIONS: The type of cement used and the light-curing access level influenced the bond strength between glass fiber posts and root canals. The bond strength of the RelyX ARC/SBMP cement proved to be more dependent on photoactivation than was the RelyX U100 cement. The light-curing access level did not influence the apical bond strength of RelyX U100.

Effect of bone marrow transplantation on the immunolocalization of p53, hMSH2, and hMLH1 proteins on oral mucosa.

OBJECTIVE: Considering that hMSH2, hMLH1 and p53 are important in maintaining genomic stability of the oral mucosa epithelium, the purpose of the present study was to investigate the immunolocalization of these proteins in the epithelium of the oral mucosa of patients submitted to bone marrow transplantation (BMT) compared with controls. MATERIALS AND METHODS: Twenty-one samples of lip biopsies from BMT recipients were retrieved. Twenty samples of normal lower labial mucosa associated with mucocele in non-transplanted patients were included as control group. The streptavidin-biotin complex stain was used to detect the human DNA mismatch repair proteins hMSH2, hMLH1 and p53 protein. RESULTS: The main findings demonstrated that the mean number of suprabasal epithelial cells positive for MSH2 was statistically higher than the control group. The immunostaining of hMLH1 and p53 at the basal and suprabasal epithelial layers were statistically higher in the oral labial mucosa of the BMT patients compared with controls. CONCLUSION: The present study shows that oral epithelial cells of BMT patients show increased immunolocalization of the DNA repair related proteins.

[Evaluation of cervical gaps in complete metal crowns cast in alternative silver-tin alloys. Relationship to investing techniques]. / Avaliação do desajuste cervical de coroas totais metálicas fundidas com ligas alternativas à base de prata-estanho. Relacionado com técnicas de inclusão.

The purpose of this study was to evaluate cervical mistifing of casting full metal crowns according to investment techniques using commercial available alloys made from silver stannum. Fifteen metal full crowns were obtained through stainless steel die with full crowns preparation, included into three groups as follows: conventional technique, vacuum technique and pressure technique. Readings of cervical disagreement were made through a comparing microscope increased 45 x and each crown was measured in 4 different regions (vestibular, lingual mesial and distal). This way it was verified which of the techniques proposed would balance the casting shrinkage for the silver-stannum alloy used. From the results obtained we conclude that the best cercical adaptation was the one got through pressure technique.

[Influence of positive pressure on gypsum bonded investments]. / Estudo da influencia da pressão positiva no revestimento aglutinado por gesso.

The work aims to investigate the influence of positive pressure to initial and final setting time, as well as the volume variation in course of the pressure carried out gypsum-bonded investment found at Dental Commerce. Seventy-six test samples were obtained, being five of them through conventional investing technique and seventy-one through technique by pressure. Gillmore needles were employed for determining the setting time, meanwhile for volumetric variation a mathematic formula had been applied. According to results, it was concluded that the use of positive pressure affected the initial and the final setting time and the volume after set.