Effect of different enamel treatments on bond strength using resin dental adhesives.

OBJECTIVE: The aim of this investigation was to evaluate the effect different cleaning techniques used on enamel surfaces have on the bond strength of a composite resin to the dental enamel. METHOD AND MATERIALS: Eighty-eight bovine enamel fragments were mounted in acrylic resin bases. The enamel surfaces were sanded using 200-, 400-, and 600-grit sandpapers, thus creating a smear layer. These surfaces were then randomly divided in 2 groups: 1 of them received salivary contact for 10 minutes, and the other received it for 60 minutes. Then all surfaces were cleaned with a pumice and water paste applied with a rubber cup, followed by the application of biological detergent, sodium bicarbonate jet, or air/water spray. After cleansing, the enamel surfaces received the application of the Scotchbond Multi-Purpose adhesive system and Z100 composite resin, following the manufacturer's instructions, using an appropriate matrix. After storage at 37 degrees C for 8 days, traction tests were carried out using an Instron machine operating at 0.5 mm/minute. Some fractured specimens (randomly chosen) were analyzed under scanning electron microscopy. RESULTS: The statistical analysis using descriptive and inferential methods did not show significant differences between the different periods of time of salivary contact. The technique of pumice and water paste cleaning followed by the application of biological detergent was significantly more efficient than the others. Scanning electron micrographs of the fragments after traction tests confirmed these results. CONCLUSION: The technique of pumice and water paste cleaning followed by the application of biological detergent was the treatment that allowed the best results in terms of resin bonding to bovine enamel covered with acquired pellicle, and the sodium bicarbonate jet technique presented the lowest bond strength values and seemed to disturb the acid conditioning of enamel surfaces.

Prevention of postoperative tooth sensitivity: a preliminary clinical trial.

The purpose of this study was to evaluate clinically the effects of pre-treatments with a 35% hydroxyethyl metacrylate/5% glutaraldehyde dentine desensitizer (Gluma Desensitizer) and a 2% chlorexidine-based cavity disinfectant (Cav-Clean) on postoperative sensitivity. Three premolar teeth with no pain symptoms were selected from each one of 17 patients, totalling 51 teeth, for which Class II restoration using a composite was indicated. Each one of the three premolar teeth of the same patient was submitted to a different treatment. After acid etching, only a dental adhesive was applied to the first tooth, which served as the control. Gluma Desensitizer dentinal desensitizer was applied to the second premolar tooth prior to applying the dental adhesive. Cav-Clean cavity disinfectant was used on the third premolar tooth before applying the dental adhesive. Only one tooth was restored per session, and all premolar teeth were restored with a condensable composite, according to current restoration technique guidelines. Sensitivity to different stimuli (cold, heat, sweet and dental floss) was assessed on Day 1, Day 4 and Day 7 by questionnaire following restorative procedures. The results of this clinical research showed that, as far as the investigated stimuli and postoperative course are concerned, there was no statistically significant difference in the three different treatments (P>0.05). Postoperative sensitivity resulting from Class II restorations using composite resin cannot be completely eliminated with the prior use of a dentinal desensitizer or a cavity disinfectant. In day-to-day clinical treatment, postoperative sensitivity may possibly be related to the technique employed.