Internal fit of two all-ceramic systems and metal-ceramic crowns.
OBJECTIVE
The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA--In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP--IPS e.max ZirCAD), and metal-ceramic (MC--Ni-Cr alloy) crowns.


METHODS
Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns was measured using the replica technique, which employs a light body polyvinyl siloxane impression material to simulate the cement layer thickness. The data were analyzed according to the surfaces obtained for the occlusal space (OS), axial space (AS) and total mean (TM) using two-way ANOVA with Tukey's multiple comparison test (p<0.05).


RESULTS
No differences among the different areas were detected in the MC group. For the Y-TZP and ICA groups, AS was statistically lower than both OS and TM. No differences in AS were observed among the groups. However, OS and TM showed significantly higher values for ICA and Y-TZP groups than MC group. Comparisons of ICA and Y-TZP revealed that OS was significantly lower for Y-TZP group, whereas no differences were observed for TM.


CONCLUSIONS
The total mean achieved by all groups was within the range of clinical acceptability. However, the metal-ceramic group demonstrated significantly lower values than the all-ceramic groups, especially in OS.
School of Dentistry, Federal University of Amazonas, Manaus, AM, Brazil. martins.l.m@gmail.com
Leandro Moura
LM
Martins
Fabio Cesar
FC
Lorenzoni
Alcides Oliveira de
AO
Melo
Luciana Mendonça de
LM
Silva
José Luiz G de
JL
Oliveira
Pedro Cesar Garcia de
PC
Oliveira
Gerson
G
Bonfante
D000537:Aluminum Oxide / Q000737:chemistry; D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry; D017076:Computer-Aided Design; D003442:Crowns; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D003765:Models, Dental; D015203:Reproducibility of Results; D013499:Surface Properties
D003188:Composite Resins; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; C070870:In-Ceram; D000537:Aluminum Oxide