An in vitro comparison of short and long term bond strengths of polyacid modified composite resins to primary human and bovine enamel and dentine.
OBJECTIVE
This in vitro study compared the shear bond strengths and fracture patterns over 7 and 180 day periods of two PMCRs bonded to both human and bovine primary tooth enamel and dentine to determine if the bovine tooth model is a suitable substitute for the human tooth model.


METHODS
Flattened enamel and dentine surfaces were produced using water irrigated #600 grit SiC paper and the teeth randomly placed in groups of N=10. Cylinders of Dyrat AP (Dentsply/DeTrey) or F2000 (3M/ESPE) were bonded to the surfaces that were either etched with 37% H(3)PO(4) (etch, E groups) or treated with their respective conditioners, primers and adhesives (no etch, NE groups). The teeth were stored in distilled water at 37(o)C and shear bond strength (SBS) tested to failure at either 7 (human and bovine) or 180 days (bovine). The modes of failure were assessed under a dissecting microscope at x30.


RESULTS
In general the results showed comparable mean SBS for both human and bovine enamel with Dyract AP, E and NE and also for F2000, E. Lower enamel SBS were recorded for F2000 NE but there was no significant differences in mean SBS for bovine enamel after long term storage. For dentine, significantly larger SBS were recorded for human versus bovine teeth for all of the four bonding protocols. There were also significant species differences, the mean SBS for Dyract AP, E and F2000, E for human dentine were higher than bovine but the mean SBS for the respective NE groups showed no significant differences between species. It was concluded that 37% H(3)PO(4) has a detrimental effect on SBS for bovine dentine. Over long term storage SBS of bovine dentine bonds decreased. The modes of failure were related to SBS with varying degrees of significance.


CONCLUSIONS
Bovine primary incisor enamel and dentine, provided the latter is not conditioned with 37% H(3)PO(4), are suitable alternative test SBS substrates for human enamel and dentine.
Titley
K C
KC
Dept Paediatric Dentistry, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada. K.Titley@utoronto.ca
Childers
S
S
Kulkarni
G
G
D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D033081:Shear Strength; D018709:Statistics, Nonparametric
D003188:Composite Resins; D017220:Dentin-Bonding Agents