Fracture resistance of teeth directly and indirectly restored with composite resin and indirectly restored with ceramic materials.
OBJECTIVE
To evaluate the fracture resistance of teeth restored with direct and indirect restorations of composite resin and restored with indirect ceramic restorations.


METHODS
Fifty-six maxillary premolar teeth were chosen and divided at random into seven equal groups; Group 1 (control): intact teeth; Group 2: MOD cavity preparations, 1/2 intercuspal distance, with rounded internal angles, convergent walls, unrestored; Group 3: MOD cavity preparations, 1/2 intercuspal distance, divergent walls; Group 4: same preparation as Group 2, restored with direct composite resin (Single Bond/Filtek Z250-3M); Group 5: same as Group 3, restored with indirect composite resin (Artglass/Single Bond/Rely X); Group 6: same as Group 3, restored with indirect composite resin (Targis/Single Bond/Rely X); Group 7: same as Group 3, restored with indirect ceramic restoration (Empress/Single Bond/Rely X). The specimens were subjected to a compressive axial loading in a Universal testing machine at 0.5 mm/minute by means of a steel bar (8 mm in diameter).


RESULTS
The mean fracture strength obtained was: Group 1: 1.91 kN; Group 2: 1.06 kN; Group 3: 0.93 kN; Group 4: 1.45 kN; Group 5: 1.81 kN; Group 6: 1.81 kN; Group 7: 1.77 kN. The restored teeth with direct composite restoration increased the fracture resistance of Group 4 up to 76% of a level comparable with the intact teeth (Group 1). However, statistical analysis indicated no significant (P < 0.05) differences between Group 1 (intact teeth) and restored teeth groups, with direct restorations as well as indirect restorations. Both cavity preparation designs weakened the remaining tooth structure. These results demonstrated that a bonded indirect restoration could satisfactorily be an ideal option for restoring teeth weakened by wide cavity preparation.
Dalpino
Paulo H P
PH
Fundação de Amparo à Pesquisa do Estado de São Paulo, Brazil.
Francischone
Carlos E
CE
Ishikiriama
Aquira
A
Franco
Eduardo B
EB
D000538:Aluminum Silicates; D000704:Analysis of Variance; D001641:Bicuspid; D003188:Composite Resins; D019245:Compressive Strength; D003737:Dental Cavity Preparation / Q000009:adverse effects*; D003776:Dental Porcelain; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements; D006801:Humans; D007284:Inlays; D008422:Materials Testing; D011897:Random Allocation; D012823:Silicate Cement; D014082:Tooth Fractures / Q000209:etiology / Q000517:prevention & control*
D000538:Aluminum Silicates; D003188:Composite Resins; C444701:Filtek Z250; D005899:Glass Ionomer Cements; C075815:IPS-Empress ceramic; C111282:dental polyglass; D003776:Dental Porcelain; D012823:Silicate Cement