All ETDs from UAB

Advisory Committee Chair

Nathaniel Lawson

Advisory Committee Members

Wen-Chou Wu

Amjad Javed

Document Type

Thesis

Date of Award

2023

Abstract

Objective: To measure and compare the bond strength of zirconia and lithium disilicate crowns bonded to human teeth (enamel and dentin) using universal adhesive with resin cement and different light curing protocols.Methods: Sixty extracted sound non carious human teeth (second premolars) were stored in formalternate solution (FormalternateTM, Concentrate, 500 mL, Canada) and the roots were notched and mounted into acrylic resin (Yates Motloid, USA). Flat surface preparation was done on the occlusal surface of the samples using model trimmer. The surface area of the specimens was measured with digital light microscopy. Samples were randomly divided into six groups of 10 specimen each according to equal surface area. Specimens were scanned using IOS Trios 3 scan (3Shape Dental Desktop v1.6.4.1; 3Shape). A total of 30 fully sintered monolithic zirconia (3Y- TZP Zirlux 16+) crowns and 30 lithium disilicate crowns of uniform thickness (1.2mm) were designed and fabricated. Adhesive (Scotch Bond Universal; 3M Oral Care, St Paul, MN, USA)and dual-cure resin cement, Rely X Ultimate (RXU; 3M Oral Care) were used for bonding the zirconia and lithium disilicate crowns to natural teeth using three different methods: 1) light-curing of adhesive and cement, 2) light curing of adhesive through the crown, or 3) complete chemical- cure (no light cure). Each crown was seated with 15N of load and allowed to self-cure for 10 minutes. After water-storage (1 week, 37◦C) and thermocycling (5-55C for 10,000 cycles), the bond strength was measured using a universal testing machine. The crowns were gripped by handles on the side of the crown and debonded using a wire loop at a speed of 1mm/min. Pull off strength (in megapascals) was analyzed with 2-factor ANOVA, separate single-factor ANOVA models for cure, and Tukey's Honestly Significant Differences multiple comparison procedure. All testing was performed at the 5% significance level (n=10). Results: The 2-way ANOVA determined that factor “cure” was significante (p=.023) but factors “material” (p=.964) and their interaction (p=.935) were not. A separate 1-way ANOVA for factor “cure” determined that there were significant differences between groups (p=.019) and a Tukey's Honestly Significant Differences test revealed that the groups in which both adhesive and cement were cured were significantly greater than the groups in which neither adhesive or cement were cured. Conclusion: In conclusion, the results of the crown pull test suggest that separately light curing the adhesive and cement in zirconia and lithium disilicate restorations leads to higher bond strength compared to not light curing the adhesive of cement. This finding highlights the importance of carefully optimizing the light curing process during adhesive cementation procedures to ensure optimal bond strength and long-term clinical success.

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