Evaluation of machinability and flexural strength of a novel dental machinable glass-ceramic.
OBJECTIVE
To evaluate the machinability and flexural strength of a novel dental machinable glass-ceramic (named PMC), and to compare the machinability property with that of Vita Mark II and human enamel.


METHODS
The raw batch materials were selected and mixed. Four groups of novel glass-ceramics were formed at different nucleation temperatures, and were assigned to Group 1, Group 2, Group 3 and Group 4. The machinability of the four groups of novel glass-ceramics, Vita Mark II ceramic and freshly extracted human premolars were compared by means of drilling depth measurement. A three-point bending test was used to measure the flexural strength of the novel glass-ceramics. The crystalline phases of the group with the best machinability were identified by X-ray diffraction.


RESULTS
In terms of the drilling depth, Group 2 of the novel glass-ceramics proves to have the largest drilling depth. There was no statistical difference among Group 1, Group 4 and the natural teeth. The drilling depth of Vita MK II was statistically less than that of Group 1, Group 4 and the natural teeth. Group 3 had the least drilling depth. In respect of the flexural strength, Group 2 exhibited the maximum flexural strength; Group 1 was statistically weaker than Group 2; there was no statistical difference between Group 3 and Group 4, and they were the weakest materials. XRD of Group 2 ceramic showed that a new type of dental machinable glass-ceramic containing calcium-mica had been developed by the present study and was named PMC.


CONCLUSIONS
PMC is promising for application as a dental machinable ceramic due to its good machinability and relatively high strength.
Qin
Feng
F
Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-Sen University, 56#, Lingyuan Xi Road, 510056 Guangzhou, Guangdong, PR China.
Zheng
Shucan
S
Luo
Zufeng
Z
Li
Yong
Y
Guo
Ling
L
Zhao
Yunfeng
Y
Fu
Qiang
Q
D000538:Aluminum Silicates; D001641:Bicuspid; D003460:Crystallization; D003743:Dental Enamel; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D005898:Glass; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D018583:Pliability
D000538:Aluminum Silicates; D003776:Dental Porcelain; C011934:mica