Influence of Enamel Exposure to Acidic Drink on Shear Bond Strength of Different Fissure Sealants.

In the present study, we evaluated the influence of bovine enamel exposure to acidic drinks (Coca-Cola, Coca-Cola Company, Milano, Italy, pH = 2.37) on shear bond strength of three sealants (Fissurit; Grandio Seal and Admira Fusion-Voco Gmbh, Cuxhaven, Germany). For each sealant, two adhesive techniques were tested to investigate the impact of the adhesive application on shear bond strength of sealants after immersion in acidic drink and in the control: Group 1-Control: enamel surface was not in contact with acid drinks, acid etching application and self-adhesive technique for fissure sealant; Group 2-enamel surface was not in contact with acid drinks, acid etching, and adhesive applications, an etch-and-rinse technique for fissure sealant; Group 3-enamel surface was immersed in acid drink, acid etching application and self-adhesive technique for fissure sealant; Group 4-enamel surface was immersed in acid drink, acid etching, and adhesive applications, an etch-and-rinse technique for fissure sealant. For each specimen, the sealant composite resin was applied to the enamel surface and tested with a universal testing machine. Shear bond strength was measured in MPa and with an optical microscope to determine failure modes, quantified with adhesive remnant index (ARI). Enamel acidification variably influenced bond strength values of the different sealants. When no enamel pretreatment was applied, no significant differences were found among the sealants (p > 0.05). However, the mere application of acid etching without adhesive procedures resulted in lower bond strength (p < 0.001). The acid pretreatment affected significantly the bond strength of all sealants tested (p < 0.001), but no significant differences were recorded between the subgroups.

Radiographic technical quality of root canal treatment performed by a new rotary single-file system.

AIM: The aim of the present study was to evaluate radiographically the technical quality of root canal filling performed by postgraduate students with a new single-file Nickel-Titanium System (F6 Skytaper Komet) in clinical practice. METHODS: Records of 74 patients who had received endodontic treatment by postgraduate students at the School of Dentistry, Faculty of Medicine, University of Pavia in the period between September 2015 and April 2016 were collected and examined: the final sample consisted 114 teeth and 204 root canals. The quality of endodontic treatment was evaluated by examining the length of the filling in relation to the radiographic apex, the density of the obturation according to the presence of voids and the taper of root canal filling. Chi-squared analysis was used to determine statistically significant differences between the technical quality of root fillings according to tooth's type, position and curvature. RESULTS: The results showed that 75,49%, 82,84% and 90,69% of root filled canals had adequate length, density and taper respectively. CONCLUSIONS: Overall, the technical quality of root canal fillings performed by postgraduates students was acceptable in 60,78% of the cases.