Effect of three direct restorative materials on molar cuspal fracture resistance.
OBJECTIVE
This study compared the cusp fracture strength of molars restored using a condensable resin composite with that of teeth restored with conventional amalgam, a bonded amalgam, and an incrementally placed resin composite.


METHODS
Standardized MOD cavity preparations (2/3 the buccal-lingual dimension x 4 mm deep) were made in 50 extracted human molars and restored as follows (n = 10): (1) a packable posterior resin composite; (2) an incrementally placed microfilled posterior resin composite; (3) a spherical particle amalgam alloy; (4) spherical amalgam with a dentin adhesive liner and (5) no restoration (preparation only; negative control). A sixth group of intact molars (n = 10) served as a positive control. Following storage and thermocycling, each specimen was tested for cuspal fracture strength.


RESULTS
Cavity preparation reduced cuspal fracture strength by over 50%. The fracture strength of intact teeth was significantly greater than that of all other groups (P< 0.0001). None of the restorative procedures increased cuspal fracture resistance over that of prepared teeth.
Allara
Frank W
FW
Dental Services, Geilenkirchen NATO Air Base, Germany, PSC 7 BOX 879, APO AE 09104. Frank.Allara@Geilenkirchen.af.mil
Diefenderfer
Kim E
KE
Molinaro
Joseph D
JD
D000134:Acid Etching, Dental; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003723:Dental Amalgam / Q000737:chemistry*; D003736:Dental Cavity Lining; D003737:Dental Cavity Preparation / Q000145:classification; D003793:Dental Restoration, Permanent / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008964:Molar, Third / Q000503:physiopathology*; D010865:Pilot Projects; D013314:Stress, Mechanical; D019228:Tooth Crown / Q000503:physiopathology*; D014082:Tooth Fractures / Q000503:physiopathology*
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D003723:Dental Amalgam