Marginal Adaptation, Gap Width, and Fracture Strength of Teeth Restored With Different All Ceramic Vs Metal Ceramic Crown Systems: An in Vitro Study.
This study evaluated marginal adaptation before and after thermomechanical (TCML) loading, gap width and fracture strength of all ceramic single crowns, as compared to porcelain fused to metal (PFM) Thirty extracted premolars were prepared with a round shoulder of 1.0 mm depth. Specimens were restored with zirconia ceramic (Group 1) lithium disilicate (Group 2) and metal ceramic single crowns (Group 3) The replica of each sample was observed with a scanning electron microscope (SEM) to evaluate the crown cement (c c) and tooth cement interface (t c) After TCML, perfect margins decreased to 91.3% (c c) and 93.9% (t c) in Group 1, 94.6% (c c) and 96.0% (t c) in Group 2 and 73.5% (c c) and 53.1% (t c) in Group 3. The mean fracture strengths were 654.8 98.1 N for Group 1, 551.3 127 N for Group 2 and 501.43 110.1 N for Group 3. All ceramic systems could substitute for metal ceramic crowns, but chipping of veneering ceramics, especially in zirconia based crowns, should be investigated.
The European journal of prosthodontics and restorative dentistry