Chlorhexidine using a 2%, 1 minute application is recommended to stabilize the collagen layer and decrease bond strength degradation
OBJECTIVE: To measure the shear bond strength to dentin at 24hours and 6months of a total- etch and self-etch adhesive after chlorhexidine was applied using 2 application times and 2 concentrations.
METHODS: 240 caries free human molars were ground to expose a flat superficial dentin with a model trimmer and finished with 320-grit SiC paper. The specimens were randomly divided into two groups. Adhesives were applied following manufactures' instructions. For Prime and Bond NT specimens, after etching with phosphoric acid either a 2% chlorhexidine solution (Cavity Cleanser/BISCO) or a .12% chlorhexidine (Peridex/3M ESPE) was applied for 15 or 60seconds. For Clearfil SE Bond chlorhexidine solutions were applied after the primer. A cylinder (1.5mm2) of composite (Z100) was placed on the cured adhesive and light-cured (3M ESPE/Elipar S10/1020mW/cm2). The specimens were stored (24hrs or 6months/distilled water/37°C), placed in a fixture in Instron-5565 and loaded to failure in shear (crosshead speed/1mm/min). Shear bond strength calculated. Data analyzed (ANOVA and Tukey/Kramer/p=0.05)
RESULTS: Mean±SD (n=10)
EXPERIMENTAL GROUPS | BOND STRENGTH (MPa) | ||||
24hours | 6month | ||||
CHX concentration | CHX application time (seconds) | Prime & Bond NT | Clearfil SE Bond | Prime & Bond NT | Clearfil SE Bond |
CHX/2% | 15 | 32.7±9 | 17.6±6 | 20.5±7 | 16.6±4 |
60 | 25.3±9 | 15.4±4 | 18.1±6 | 18.9±5 | |
CHX/0.12% | 15 | 28.5±10 | 35.1±5 | 13.3±7 | 29.9±7 |
60 | 29.1±8 | 28.6±8 | 19.5±6 | 21.5±9 | |
Control | 15 | 27.3±9 | 30.9±6 | 21.6±11 | 32.8±6 |
60 | 35.2±8 | 27.8±4 | 17.1±6 | 25.2±7 | |
CONCLUSIONS: In this in vitro study 0.12 or 2% chlorhexidine applications did not alter bond strengths significantly for Prime and Bond NT. 0.12% chlorhexidine produced significantly better bonds compared to the 2% solution for Clearfil SE Bond. Overall the groups were not different from controls. NSF EEC-0244050 Grant and NIDCR T32-DE017607, M. MacDougall-PI, DART Short-term Training for Dental Students