Shuang Xi1, Zi-Xiao Wu1, Cui-Cui Gao1, Yu-Chen Meng1, Dan-Dan Pei1, Yi Lu1. 1. Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases & Dept. of Prothodontics, College of Stomatology, Xi'an Jiaotong University, Xi'an 710004, China.
Abstract
OBJECTIVE: To investigate the effects of preparation height and cement space on the fit and retention of computer aided design (CAD)/computer aided manufacturing (CAM) zirconia crown, and to provide reference for the clinical design and fabrication of CAD/CAM crowns. METHODS: 3D printing system was used to fabricate resin abutment teeth with convergence angle of 2° and height of 1-3 mm. The models' optical impressions were collected by the three-shape scanner. Then, the cement spaces were set by Cradle CAD/CAM system at 10-50 μm to create an all-ceramic zirconia crown. The fit of the crowns was measured by using silicone rubber interstitial impression method. The retention of the crowns was measured by pull-off test with uniaxial tensile force after the crown was bonded. The data were analyzed by SPSS 22.0 soft-ware. RESULTS: When the preparation height was fixed, the fitness values of different cement space groups have statistical difference (P< 0.05), whereas the retention values of different cement space groups have no statistical difference (P>0.05). The fitness values of different preparation height groups have no statistical difference (P>0.05), and the retention values of different preparation height groups have statistical difference (P<0.05) when the cement space was fixed. No interaction was observed between the cement space and the preparation height (P>0.05). CONCLUSIONS: When cradle CAD/CAM system is used to create a full crown in the clinic, the preparation height should be set to more than 3 mm, and the cement space should be set at 30 μm.
OBJECTIVE: To investigate the effects of preparation height and cement space on the fit and retention of computer aided design (CAD)/computer aided manufacturing (CAM) zirconia crown, and to provide reference for the clinical design and fabrication of CAD/CAM crowns. METHODS: 3D printing system was used to fabricate resin abutment teeth with convergence angle of 2° and height of 1-3 mm. The models' optical impressions were collected by the three-shape scanner. Then, the cement spaces were set by Cradle CAD/CAM system at 10-50 μm to create an all-ceramic zirconia crown. The fit of the crowns was measured by using silicone rubber interstitial impression method. The retention of the crowns was measured by pull-off test with uniaxial tensile force after the crown was bonded. The data were analyzed by SPSS 22.0 soft-ware. RESULTS: When the preparation height was fixed, the fitness values of different cement space groups have statistical difference (P< 0.05), whereas the retention values of different cement space groups have no statistical difference (P>0.05). The fitness values of different preparation height groups have no statistical difference (P>0.05), and the retention values of different preparation height groups have statistical difference (P<0.05) when the cement space was fixed. No interaction was observed between the cement space and the preparation height (P>0.05). CONCLUSIONS: When cradle CAD/CAM system is used to create a full crown in the clinic, the preparation height should be set to more than 3 mm, and the cement space should be set at 30 μm.
Authors: Tamer A Hamza; Hesham A Ezzat; Mohamed Mahmoud Khalil El-Hossary; Hesham Abd El Megid Katamish; Tamer E Shokry; Stephen F Rosenstiel Journal: J Prosthet Dent Date: 2013-02 Impact factor: 3.426