IADR Abstract Archives
Effect of Thermal Tempering on the Marginal Adaptation of Heat Pressed Lithium Disilicates Crowns
Objectives: To Evaluate the effect of two thermal tempering temperatures on marginal adaptation of different lithium silicate/disilicate crowns
Methods: A prototype tooth was prepared using a computerized numerical control(CNC)milling machine to receive a full coverage all ceramic crown.Fifty-six wax patterns were milled and randomly allocated to four groups fourteen pattern each(n=14).Each group was heat pressed of a different all ceramic material.Lithium disilicates are(IPS e.max Press,Ivoclar Vivadent),High Density Micronization(HDM),(GC initial LiSi Press, GC),Zirconia reinforced lithium silicate/disilicate are(Celtra Press,Dentsply Sirona),(VITA Ambria,VITA Zahnfabrik).Each group was divided into two subgroups according to temperature of tempering cycle,-5%and-9%thermal tempering.The vertical marginal gap was evaluated by stereomicroscope.Three-way ANOVA test was used to study the effect of ceramic type,tempering,tempering procedures and their interactions on marginal gap distance.Bonferroni’s post-hoc test was used for pair-wise comparisons when ANOVA test is significant.The significance level was set at P≤0.05.Statistical analysis was performed
Results: The results showed that ceramic type(regardless of tempering temperature and tempering procedures)had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.974).Tempering temperature(regardless of ceramic type and tempering procedures) had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.932).tempering procedures(regardless of ceramic type and tempering temperature)had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.94).The interaction between the three variables had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.976).
Conclusions: All groups showed clinically acceptable marginal gap<120µm except Zirconia reinforced lithium silicate with -5%tempering.
Zirconia reinforced lithium silicate showed the statistically significantly highest mean marginal gap distance after -5%tempering.
5%tempering cycle showed statistically significantly higher mean marginal gap distance than -9%tempering in all groups-.
All groups showed a statistically significant increase in mean marginal gap distance after tempering
Methods: A prototype tooth was prepared using a computerized numerical control(CNC)milling machine to receive a full coverage all ceramic crown.Fifty-six wax patterns were milled and randomly allocated to four groups fourteen pattern each(n=14).Each group was heat pressed of a different all ceramic material.Lithium disilicates are(IPS e.max Press,Ivoclar Vivadent),High Density Micronization(HDM),(GC initial LiSi Press, GC),Zirconia reinforced lithium silicate/disilicate are(Celtra Press,Dentsply Sirona),(VITA Ambria,VITA Zahnfabrik).Each group was divided into two subgroups according to temperature of tempering cycle,-5%and-9%thermal tempering.The vertical marginal gap was evaluated by stereomicroscope.Three-way ANOVA test was used to study the effect of ceramic type,tempering,tempering procedures and their interactions on marginal gap distance.Bonferroni’s post-hoc test was used for pair-wise comparisons when ANOVA test is significant.The significance level was set at P≤0.05.Statistical analysis was performed
Results: The results showed that ceramic type(regardless of tempering temperature and tempering procedures)had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.974).Tempering temperature(regardless of ceramic type and tempering procedures) had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.932).tempering procedures(regardless of ceramic type and tempering temperature)had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.94).The interaction between the three variables had a statistically significant effect on mean marginal gap distance(P-value<0.001,Effect size=0.976).
Conclusions: All groups showed clinically acceptable marginal gap<120µm except Zirconia reinforced lithium silicate with -5%tempering.
Zirconia reinforced lithium silicate showed the statistically significantly highest mean marginal gap distance after -5%tempering.
5%tempering cycle showed statistically significantly higher mean marginal gap distance than -9%tempering in all groups-.
All groups showed a statistically significant increase in mean marginal gap distance after tempering