H. Moscovich et al., EFFECT OF COMPOSITE BASING ON THE RESISTANCE TO BULK FRACTURE OF INDUSTRIAL PORCELAIN INLAYS, Journal of dentistry, 26(2), 1998, pp. 183-189
Objectives. Bases are used in restorative dentistry for several reason
s (i.e. isolation, elimination of undercuts, etc). Glass ionomers are
the standard materials used as bases for porcelain inlays, despite the
disadvantages of their mechanical properties. An alternative basing m
aterial is composite: a generous layer of posterior composite is cured
and shaped in the cavity before an impression is taken. The composite
basing technique has several clinical advantages. The aim of this stu
dy was to investigate the effect of the thickness of a composite base
on the bulk fracture resistance of industrial porcelain, and to descri
be the procedure. Methods. Fifteen porcelain (P) and 15 composite (C)
bars, 1-, 2-, and 3-mm thick were joined to form 15 CIP bars, all 4-mm
thick. Three groups were created: C 1 mm/P 3 mm (group 1), C 2 mm/P 2
mm (group 2), and C 3 mm/P 1 mm (group 3). The pairs were joined usin
g Twinlook cement, subjected to a three-point bending test and loaded
to fracture. The beam theory was used to support and explain the resul
ts. Results: The fracture load means were: group 1, 197.7+/-18.7 N; gr
oup 2, 234.3+/-63.3 N, group 3, 336.3 +/- 31.3 N. Group 3 was signific
antly stronger than group 1 (P=0.01) and group 2 (P=0.03). Groups 1 an
d 2 were not statistically different. Conclusion: Composite basing is
a tissue conserving method which may significantly increase the resist
ance to bulk fracture of adhesive porcelain inlays. (C) 1998 Elsevier
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