Objective: To evaluate the post-operative sensitivity of occlusal restorations using different dentin adhesives performed by an undergraduate and a post-doctorate dentist. Materials and Methods: One hundred and eighty-eight molar occlusal restorations were placed in 39 patients (ages between 18 and 30) using 3 different kind of adhesive systems; Optibond FL (OBF), Clearfil Protect Bond (CPB), and iBond (IB) by a post-doctorate dentist or a fifth-year dental student according to the manufacturers' instructions. Post-operative sensitivity to cold and air was evaluated using a Visual Analog Scale (VAS) after 24 hours, 30, 90, and 180 days. Data were analyzed using the Mann-Whitney U and Friedman tests (P < 0.05). Results: Post-operative sensitivity scores for OBF and CPB were higher for the dental student (P < 0.05), while IB scores did not differ statistical significantly according to the operator (P > 0.05). Conclusion: Operator skill and experience appears to play a role in determining the outcome of post-operative sensitivity of multi-step adhesive systems although the post-operative sensitivity was low. It is suggested that the less experienced clinicians (rather than experienced clinicians) should better use the self-etching dentin bonding systems with reduced application steps to minimize the potential risk of post-operative sensitivity of dental adhesives.

Objective: The aim of the present study was to evaluate the effects of different surface pre-treatment techniques on the microleakage of a resin-based fissure sealant material. Methods: Thirty-five molars were divided into the following seven groups based on the surface pre-treatment technique used: (a) Erbium: Yttrium Aluminium Garnet (Er:YAG) laser (7 W); (b) Er:YAG laser (7 W)+acid etching (with 37% phosphoric acid); (c) Er:YAG laser (5.5 W); (d) Er:YAG laser (5.5 W)+acid etching; (e) air abrasion+acid etching; (f) air abrasion; and (g) conventional acid etching. The sealant was placed according to the manufacturers' instructions and light-cured for 20 sec. The sealed teeth were thermocycled for 10,000 cycles (5°-55°C), then immersed in 5% methylene blue for 24 h and sectioned mesiodistally. Each section was analyzed and photographed using a light microscope. Microleakage was assessed quantitatively by the degree of dye penetration and also qualitatively, scored on a three-point rating scale. Data were analyzed by one-way analysis of variance (ANOVA) and the Kruskal–Wallis test. The level of significance was set at p < 0.05. Results: Regardless of the fissure morphology and penetration depth, enamel surfaces conditioned with Er:YAG laser irradiation exhibited significantly higher microleakage than those conditioned with air abrasion followed by acid etching, and those conditioned with conventional acid etching ( p < 0.05). Air abrasion followed by acid etching, as well as conventional acid etching, provided a sufficient seal, whereas laser irradiation alone or in combination with acid etching exhibited higher microleakage than did the other groups. Conclusions: Conventional acid etching remains the most effective and the simplest technique.