Effect of root perforation repair with mineral aggregate-based cements on the retention of customized fiberglass posts

Odontology - The purpose of this study was to investigate whether the root perforation repair with mineral aggregate-based cements affects the retention of customized fiberglass posts to bovine...     

Interfacial evaluation of experimentally weakened roots restored with adhesive materials and fibre posts: an SEM analysis

OBJECTIVES: To evaluate the bonding interface in experimentally weakened roots reinforced with adhesive restorative materials and quartz fibre posts, varying the light-exposure time of the composite resin used for root reinforcement. METHODS: Twelve extracted human maxillary incisors teeth were used. The crowns were removed and the roots were endodontically treated. After post space preparation, the roots were assigned to four groups. The thickness of the root dentine was reduced and adhesively restored with composite resin light-activated through a translucent fibre post for either 40s (group 1), 80s (group 2) or 120s (group 3). In the case of control (group 4), the roots were not weakened. One day after post cementation, the specimens were sectioned transversally in three slices and processed for scanning electron microscopic analysis to observe bonding interface formation, quality of the hybrid layer and density of resin tags using a four-step scale method. RESULTS: Formation of a hybrid layer and resin tags were evident in all groups. There was no statistically (p>0.05) significant difference between the regions analysed in each group (Friedman test) and between groups in each section depth (Kruskal-Wallis test). Furthermore, comparison of the flared/reinforced groups showed that the different times used for composite resin cure did not affect the results significantly (Kruskal-Wallis test, p=0.2139). CONCLUSIONS: Different light-exposure times used for composite resin polymerisation during root canal reinforcement did not affect significantly the formation and quality of the dentine/adhesive/composite resin bonding interface.     

Treatment of a second maxillary molar with six canals

Variations in the dental anatomy are found in all teeth. Knowledge of these variations, particularly concerning the location and treatment of all canals, is very important for the success of the endodontic therapy. The purpose of this study is to present a clinical case of a maxillary second molar with three palatal canals, two mesio-buccal and one disto-buccal canal. This report serves to remind clinicians that such anatomical variations should be taken into account during endodontic treatment of the maxillary molars.     

alpha-Tocopherol as an antiretroviral therapy supplement for HIV-1-infected patients for increased lymphocyte viability.

The aim of our study was to evaluate the benefits of supplementation with 800 mg/day of alpha-tocopherol with regard to cellular viability in HIV-1 seropositive patients undergoing anti-retroviral therapy. A total of 29 patients participated in the study, of whom 14 were given the supplement and 15 a placebo. The analyses were carried out before treatment commenced and after 60, 120 and 180 days. The plasma levels of HIV-1 RNA showed a significant decrease as a consequence of treatment time in the groups studied (p = 0.0001), although the difference between the treatments over time was not verified (p = 0.7343). The percentage of viable lymphocytes showed a significant increase as a consequence of treatment time in both groups studied (p = 0.0002) and a significant difference between the treatments over time (p = 0.0472). The percentage of lymphocytes in apoptosis showed a significant reduction over time (p = 0.0003), as well as a significant difference between the treatments over time (p = 0.0321). The significant increase in cellular viability indicates that supplementation with alpha-tocopherol offers an additional positive effect on cellular preservation in HIV-1 individuals undergoing anti-retroviral therapy; however, it represents an additional risk of anti-retroviral therapeutic failure, possibly due to drug-drug interaction involving up-regulation of metabolic clearance.     

ADHESION OF AN ENDODONTIC SEALER TO DENTIN AND GUTTA-PERCHA: SHEAR AND PUSH-OUT BOND STRENGTH MEASUREMENTS AND SEM ANALYSIS

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and guttapercha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student''s t-test (α=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to guttapercha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.     

Effect of HBSS storage time on human periodontal ligament fibroblast viability

Abstract – Hank’s balanced salt solution (HBSS) is recommended for the storage of avulsed teeth. The objective of this study was to evaluate if the HBSS storage time influences its ability to maintain the viability of human periodontal ligament fibroblasts (PDLF) by the analysis of cell metabolic function using MTT assay. PDLF were kept at 20°C for 3, 6, 24, 48, 72, 96 and 120 h in recently prepared HBSS (HBSS), HBSS stored for 6 months (HBSS 6 M), HBSS stored for 12 months (HBSS 12 M), and in Save‐A‐Tooth system’s HBSS (Save). Minimum essential medium (MEM) at 37°C and tap water at 20°C served as positive and negative controls, respectively. Cell viability was determined by the tetrazolium salt‐based colorimetric (MTT) assay. Data were statistically analyzed by the Kruskal–Wallis and Scheffé tests (α = 5%). Starting with the 6 h time‐point, HBSS was significantly more effective than HBSS 6 M, HBSS 12 M and Save in maintaining cell viability. HBSS 6 M effectiveness was similar to that of HBSS 12 M for up to 48 h, becoming higher at 72 h. In conclusion, the storage time of HBSS had a negative influence on its ability to maintain PDLF viability.