Dentin Hydraulic Conductance Effects of Diamond and Carbide Burs

Methods: 108 healthy human third molar, recently extracted, without occlusal contact(patients between 15-30 years). They were cleaned (Gracey 13-14,HuFriedy,USA), disinfected(Tymol 0.1%-24 hrs) and stored in Hanks Balance Salt Solution (Sigma-UK) at room temperature during 15 days. Specimens were included in epoxy resin. From each tooth was obtained a dentin disk of 1mm thickness(Isomet-1000-Buehler-LakeBuff-IL-USA), parallel to occlusal surface, under the following treatment (n=12 each group): Group A: (control):  regularized by abrasive paper (Nº600-Silicon-Carbide-SIA, Switzerland) treated by orthophosphoric acid 35%(Etchant-Gel-Coltene-Whaledent-Switzerland) for 15 seconds  and washed by distilled water (1 min). For the following 8 treatment groups dentin disks were obtained by cutting the occlusal surface with cylindrical rotary instruments(Hager-Meisinger GmbH, Germany) (PanAir, PA-S B2, NSK, Japan) mounted in a support(Robert Bosch Tool Corporation-Dremel-USA), pulp surface were obtained as group A. Group B and F: medium-grain diamond, C and G: coarse-grain diamond, D and H: fine-grain Diamond, E and I: carbide bur. Groups B, C, D and E were treated by acid etch. The hydraulic conductance was determined by experimental model(Pashley et al) under a constant pressure of 200mm height H₂O. Statistical analysis was performed by ANOVA test and Tuckey post-hoc(SPSS15v1)

Results:

Conclusion: Anova test showed differences in hydraulic conductance between groups(p=0.000). When comparing treatment groups, differences were seen between etched groups and non etched groups(p=0.000). No differences were seen between different rotary instruments. Disk treatment with diamond and carbide burs reduce dentin hydraulic conductance(p=0.000). 

Study ascribed to Transdentin Diffusion Project-PRI-ODO-UChile. Study partially sponsored by Colgate-Palmolive-Chile Grant.