Evaluation of Marginal Accuracy and Microstructure of Heat Pressed Lithium Disilicate and Zirconia Reinforced Lithium Silicate Crowns after Thermal Tempering | ||||
| Egyptian Dental Journal | ||||
| Volume 69, Issue 3, July 2023, Page 2083-2091 PDF (1007.27 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/edj.2023.187867.2412 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
Mohammad abdelkhader   1; Amr El-Etreby 2; Marwa Emam 3
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| 1Master’s degree student, Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt. | ||||
| 2Professor, Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt. | ||||
| 3Lecturer, Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt. , Visiting researcher, Oral Technology, Rheinische Friedrich-Wilhelms University, Hospital Bonn, Germany. | ||||
| Abstract | ||||
| Objectives: To evaluate the effect of two thermal tempering cycles on marginal accuracy of crowns fabricated from two heat-pressed glass ceramics. Materials and methods: Twenty-eight ceramic crowns were pressed from glass ceramic materials in two groups (n=14). Group (E): Lithium disilicate IPS e.max Press, Group (C): Zirconia reinforced lithium silicate (ZLS) Celtra Press. Each group was subdivided according to tempering temperature into (T1) 9% and (T2) 5% below pressing temperature of each ceramic. A stereomicroscope was used to measure the marginal adaptation before and after tempering and microstructure was analyzed. Three-way ANOVA test was used to study the effect of ceramic type, tempering, tempering procedure 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. Results: The interaction between the three variables had statistically significant effect on mean marginal gap distance (P-value <0.001). Before tempering and after (T1) tempering, there was no statistically significant difference between ceramic types (P-value = 0.577). After (T2) tempering, there was a statistically significant difference between ceramic types (P-value <0.001). Celtra showed statistically significantly higher mean marginal gap distance compared to E.max. Conclusions: Mean marginal gap distance for lithium disilicate was not affected after tempering. ZLS after -5% tempering showed the highest mean marginal gap distance. All tested groups showed clinically acceptable marginal adaptation except ZLS with -5% tempering which showed clinically unacceptable marginal adaptation >120 µm. | ||||
| Keywords | ||||
| lithium disilicate; zirconia lithium silicate; thermal tempering; marginal adaptation; microstructural analysis | ||||
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