Effect of a new local anesthetic buffering device on pain reduction during nerve block injections.

The purpose of this double-blind, split-mouth, randomized human clinical study was to evaluate the effectiveness of a new sodium bicarbonate local anesthetic buffering device (Onset) in reducing pain associated with dental injections. Twenty patients were given bilateral inferior alveolar (IA) and long buccal (LB) nerve block injections and asked to quantify the pain experienced during injection on a visual analog scale (0, no pain; 10, worst possible pain). One side of the mouth received standard-of-care injections of 2% lidocaine with 1:100,000 epinephrine. On the opposite side, after the buffering device was used to mix the components within the anesthetic carpule, patients received injections of 2% lidocaine with 1:100,000 epinephrine buffered 9:1 with 8.4% sodium bicarbonate. The mean pain scores were 2.7 (SD, 1.3) for buffered and 2.7 (SD, 1.9) for unbuffered IA injections. The mean pain scores were 2.0 (SD, 1.4) for buffered and 2.7 (SD, 1.8) for unbuffered LB injections. The data were analyzed with a paired t test (α = 0.05), and no statistically significant difference was found between groups for IA (P = 0.94) or LB (P = 0.17) nerve block injections. In this study of patients receiving common dental nerve block injections, local anesthetic buffering technology did not significantly lessen pain compared to that experienced during a standard unbuffered injection.

The effect of saliva contamination on enamel and dentin using a self-etching adhesive.

BACKGROUND: The authors conducted a study to evaluate the effect of saliva contamination on enamel and dentin before or after application of a self-etching adhesive. METHODS: The authors divided 120 extracted molars into enamel and dentin groups of 60 specimens each, and then further divided each group into three groups of 20 specimens each. Resin-based composite cylinders were bonded to tooth specimens that were uncontaminated (control) or were contaminated with saliva either before or after application of the adhesive and then loaded to the failure point. The authors calculated the mean shear bond strength for each group and subjected data to a one-way analysis of variance, or ANOVA, to test for differences among groups. RESULTS: Mean shear bond strength was 16.7 megapascals (+/- 3.0 standard deviation, or SD) for the dentin control group, 14.8 MPa (+/- 2.3 SD) for dentin contaminated with saliva before adhesive application, 15.9 MPa (+/- 3.8 SD) for dentin contaminated with saliva after adhesive application, 19.1 MPa (+/- 4.8 SD) for the enamel control group, 12.3 MPa (+/- 4.4 SD) for enamel contaminated with saliva before adhesive application, and 13.1 MPa (+/- 5.5 SD) for enamel contaminated with saliva after adhesive application. One-way ANOVA detected no difference in the dentin groups, but the authors found a significant difference among enamel groups. Uncontaminated enamel had higher bond strengths than either of the contaminated enamel groups. CONCLUSIONS: Saliva contamination did not affect the dentin shear bond strength of the self-etching adhesive. Saliva did have a detrimental effect on enamel bond strength. CLINICAL IMPLICATIONS: Newer generations of adhesives appear to be more tolerant of saliva contamination, but proper isolation still should be accomplished until further research proves otherwise.