The effect of film thickness and surface texture on the resistance of cemented extracoronal restorations to lateral fatigue loading.
OBJECTIVE
The aim of the present study was to assess the effect of cement-film thickness and surface texture (roughness) on the resistance of cemented crowns to dynamic lateral loading.


METHODS
Crown and abutment analogues were cemented using zinc-oxide-eugenol, zinc-phosphate, glass-ionomer, and composite cements. The space left for the cement lute was 0.02, 0.05, 0.1, 0.2, and 0.5 mm. The 3 degrees of surface texture subjected to investigation were (1) polished with up to 4,000-grit paper, (2) sanded using a 1,000-grit paper, and (3) sandblasted with 50-micron aluminum oxide. Testing was conducted according to the staircase procedure. The specimens were subjected to rotational fatigue loading until the cement bond failed or the components reached 1,000,000 stress cycles.


RESULTS
The results showed that the relation between cement thickness and resistance to dynamic lateral loading is hyperbolic. For the zinc-oxide-eugenol, the zinc-phosphate, and the glass-ionomer cements increasing surface texture had a moderate effect. For composite cement, sandblasting doubled the resistance to dynamic lateral loading. For both parameters tested (cement thickness and surface texture), the ascending order of resistance was: zinc-oxide-eugenol, zinc-phosphate, and glass-ionomer cements. Crowns cemented with composite cement presented the highest resistance to dynamic lateral loading.


CONCLUSIONS
Within the confines of the present experimental design, it is concluded that (1) decreasing the width of the cement layer increases the resistance to dynamic lateral loading, and (2) texturing the surface of the abutment and the restorations as after sandblasting increases the resistance to dynamic lateral loading.
Wiskott
H W
HW
Division of Fixed Prosthodontics, School of Dentistry, University of Geneva, Switzerland. Anselm@Wiskott.com
Belser
U C
UC
Scherrer
S S
SS
D002484:Cementation; D003442:Crowns; D000044:Dental Abutments; D001840:Dental Bonding; D003738:Dental Cements; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements; D008422:Materials Testing; D019279:Resin Cements; D013499:Surface Properties; D015035:Zinc Oxide-Eugenol Cement; D015036:Zinc Phosphate Cement
D003738:Dental Cements; D005899:Glass Ionomer Cements; D019279:Resin Cements; D015035:Zinc Oxide-Eugenol Cement; D015036:Zinc Phosphate Cement