Evaluation of different methods of optical impression making on the marginal gap of onlays created with CEREC 3D.
OBJECTIVE
This study evaluated the marginal gaps on several surfaces of onlays created with the Cerec 3D system using one intraoral and two extraoral optical impression methods.


METHODS
A human molar (#19) was mounted with its adjacent teeth on a typodont (Frasaco) and prepared for a MODL onlay. The typodont was assembled in the mannequin head in order to simulate clinical conditions. The same operator took 36 individual optical impressions using a CEREC 3D camera. For group 1 (IP), a thin layer of titanium dioxide powder (CEREC powder-VITA) was applied directly onto the surface of the preparation for imaging (n = 12). For group 2 (EP), a sectional impression was taken with hydrocolloid Identic Syringable (Dux Dental), a die made with polyvinylsiloxane KwikkModel Scan (R-dental Dentalerzeugnisse GmbH) and powdered with titanium dioxide for imaging (n = 12). For group 3 (ES), a sectional impression was taken with PVS and a sectional stock tray, a die fabricated in stone (Diamond die- HI-TEC Dental Products) and the die being imaged without powdering (n = 12). One operator designed and machined the onlays in VitaBlocks Mark II for Cerec (VITA) using a CEREC 3D. The marginal gaps (microm) were measured with an optical microscope (50x) at 12 points, three on each surface of the MODL. The results were analyzed by two-way ANOVA/ Tukey's (p = 0.05).


RESULTS
The overall mean marginal gaps (microm) for the three methods were: IP = 111.6 (+/- 34.0); EP = 161.4 (+/- 37.6) and ES = 116.8 (+/- 42.3). IP and ES were equal, but both were significantly less than EP. The pooled mean marginal gaps (microm) for the occlusal = 110.5 (+/- 39) and lingual = 111.5 (+/- 30.5) surfaces were equivalent and significantly less than the distal = 136.5 (+/- 42.5) and mesial = 161.1 (+/- 43.3).


CONCLUSIONS
The marginal gap of CEREC 3D onlay restorations was not different when the optical impression was taken intraorally vs extraorally using a stone cast that does not require powdering. The lingual and occlusal surfaces showed the lowest gaps.
da Costa
Juliana B
JB
Oregon Health & Science University, Portland, OR, USA. dacostaj@ohsu.edu
Pelogia
Fernanda
F
Hagedorn
Bradley
B
Ferracane
Jack L
JL
D002133:Calcium Sulfate / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D017076:Computer-Aided Design; D003737:Dental Cavity Preparation / Q000379:methods; D003760:Dental Impression Materials / Q000737:chemistry; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007284:Inlays; D008422:Materials Testing; D008963:Molar; D023861:Photography, Dental / Q000295:instrumentation; D011145:Polyvinyls / Q000737:chemistry; D011208:Powders; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
D003102:Colloids; D003760:Dental Impression Materials; D003764:Dental Materials; D011145:Polyvinyls; D011208:Powders; D012833:Siloxanes; C034183:vinyl polysiloxane; C009495:titanium dioxide; D014025:Titanium; D002133:Calcium Sulfate