The effect of finish line curvature on marginal fit of all-ceramic CAD/CAM crowns and metal-ceramic crowns.
OBJECTIVE
To investigate the effect of abutment finish line curvature on the fit of all-ceramic CAD/CAM crowns and metal-ceramic crowns.


METHODS
Three types of finish line curvature abutments (1-, 3-, and 5-mm curvature) were prepared on typodont maxillary central incisors. For each type of abutment, 5 all-ceramic crowns (Cercon system, DeguDent) and 5 metal-ceramic crowns were fabricated. The marginal gaps of copings and veneered crowns were measured on a profile projector. The data were calculated and analyzed with 2-way ANOVA and Tukey HSD test (alpha = .05).


RESULTS
The mean labial, lingual, mesial, and distal marginal gaps (SD) of all-ceramic crowns were similar: respectively, 54 (10), 51 (11), 47 (13), and 49 (9) microm for 1-mm curvature; 49 (12), 53 (11), 54 (10), and 55 (12) microm for 3-mm curvature; and 57 (12), 54 (11), 53 (10), and 52 (9) microm for 5-mm curvature. The mean labial, lingual, mesial, and distal marginal gaps (SD) of metal-ceramic crowns were 36 (7), 41 (9), 26 (8), and 28 (10) microm, respectively, for 1-mm curvature. The mean labial and lingual marginal gaps (SD) of metal-ceramic crowns for 3-mm curvature were 45 (8) and 48 (9) microm, respectively-significantly larger than mesial (P = .01 and .007) and distal (P = .03 and .02) gaps. The mean labial and lingual marginal gaps (SD) of metal-ceramic crowns for 5-mm curvature were 76 (10) and 74 (15) microm, respectively-significantly larger than mesial (P = .001 and .001) and distal (P = .001 and .001) gaps.


CONCLUSIONS
The abutment finish line curvature had no significant effect on the marginal fit of all-ceramic crowns, but had a significant effect on the marginal fit of metal-ceramic crowns.
Tao
Jianxiang
J
Department of Prosthodontics, School of Stomatology, Tongji University, Shanghai 200072, China. taojxtohoku@hotmail.com
Han
Dongwei
D
D000537:Aluminum Oxide / Q000737:chemistry; D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D045662:Dental Etching / Q000379:methods; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003801:Dental Veneers; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007180:Incisor; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D003765:Models, Dental; D010165:Palladium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D019246:Tooth Preparation / Q000379:methods
D006047:Gold Alloys; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D012834:Silver; D010984:Platinum; D010165:Palladium; D000537:Aluminum Oxide