Files and links (1)
Khulood MS - final_after review 1.07 MB
Embargoed Access, Embargo ends: 07/01/2026
Thesis
Impact of preparation designs and computer-aided design/computer-aided manufacturing materials on the fracture resistance of dental posterior indirect adhesive restorations
University of Iowa
Master of Science (MS), University of Iowa
Spring 2024
DOI: 10.25820/etd.007401
Abstract
This study evaluated two Posterior Indirect Adhesive Restorations (PIARs) preparation designs restored with different Computer-aided design and Computer-aided manufacturing (CAD/CAM) materials on the tooth-restoration fracture resistance as compared with sound tooth structure. The tested null hypotheses were: there will be no difference in the fracture resistance between the control group and the different PIAR designs, and there will be no difference in the fracture resistance between the control group and the different CAD/CAM materials. Seventy-five crack-free, sound human molars (n=15/group) were randomly divided into five groups: C (Control, sound tooth), A-Hyb (Design-A preparation with rounded-shoulder finish line) restored with hybrid nano ceramic block, A-LiSi (Design-A prep with rounded-shoulder finish line) restored with lithium disilicate block, B-Hyb (Design-B preparation with butt-joint finish line) restored with hybrid nano ceramic block, B-LiSi (Design-B prep with butt-joint finish line) restored with lithium disilicate block. The cementation process involved selective enamel etch, followed by application a self-adhesive primer and self-adhesive resin cement. The specimens were thermo-cycled (10,000 cycles, simulating approximately 1 year of aging), followed by mechanical cycling (500,000 cycles at 50 N, positioned 90° with the occlusal surface at a frequency of 1 Hz, simulating approximately 2 years of aging). The fracture resistance of the tooth-restoration system was assessed through a compressive test using a Zwick universal machine. The specimens were subjected to compressive load at a 90° angulation using a 5 mm stainless-steel conical-shaped piston in a compression test apparatus until fracture. Statistical analysis was conducted using two-way ANOVA to compare the means among the five groups, and Tukey post hoc tests to compare the mean pairwise if a significant difference was found at α = 0.05. Further statistical analysis was undertaken through linear regression analysis, aimed at explaining the relationships between material types, preparation designs, and the fracture pattern. The control group data was integrated as a reference level within the regression framework enabling the interpretation of coefficients, providing insight into how each variable’s alteration influences the fracture resistance relative to control. All tests were done with the type-1 error rate of α = 0.05. The results revealed that no statistically significant differences were observed among groups considering preparation design (p = 0.972) or materials (p = 0.278) and they were not statistically significant differences in relation to the sound tooth (p > 0.05). The regression analysis showed a significant correlation in the value of the fracture resistance (Fmax) between the cracked group and the other fracture pattern gropes. Specimens with the lowest Fmax values demonstrated crack type of fracture; while type IV had the highest mean Fmax value. In conclusion, PIARs fabricated with CAD/CAM materials achieved comparable fracture resistance to those of sound teeth when applied with precision and adherence to clinical and manufacturing guidelines regardless of the preparation design and the material selection. There were no differences in fracture resistance regardless of the material type and the preparation design.
Details
- Title: Subtitle
- Impact of preparation designs and computer-aided design/computer-aided manufacturing materials on the fracture resistance of dental posterior indirect adhesive restorations
- Creators
- Khulood K. Alzahrani
- Contributors
- Ariene Leme Kraus (Advisor)Erica Teixeira (Committee Member)Marcos Vargas (Committee Member)Natalia Restrepo-Kennedy (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Oral Science
- Date degree season
- Spring 2024
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.007401
- Number of pages
- xi, 60 pages
- Copyright
- Copyright 2024 Khulood K Alzahrani
- Language
- English
- Date submitted
- 04/22/2024
- Description illustrations
- illustrations, tables, graphs
- Description bibliographic
- Includes bibliographical references (pages 53-56).
- Public Abstract (ETD)
- This research focused on comparing the durability of two different tooth preparation designs, known as posterior indirect adhesive restorations (PIAR), made with modern technology that enables the design and fabrication of dental restorations using a computerized system known as Computer-aided design and Computer-aided manufacturing (CAD/CAM) to ensure high precision and efficiency. We tested how well two different PIAR designs, made from advanced dental materials, could withstand pressure compared to unaffected, healthy teeth. The study involved testing in the laboratory 75 human molars under conditions that mimic the mechanical and thermal stresses teeth may undergo over about three years. The teeth were divided into groups: one with sound or intact teeth and the others featuring various combinations of restorative designs and materials. We subjected these teeth to intense compressive pressure to determine at what point they would break, using a process that simulates the kind of force a tooth would experience in daily use. Our finding showed that the type of material or the specific design of the PIAR did not significantly impact the tooth’s ability to resist breaking when compared to an unaltered tooth. We also found that the pattern of how these materials broke under pressure varied, with some types of fractures able to withstand more force than others. The conclusion from our study is reassuring for dental practice: when meticulous care is taken in applying these advanced repair materials and methods, the restored teeth can be just as robust as their healthy counterparts, regardless the effectiveness of modern dental restoration techniques, offering promising outcomes for patients receiving such treatments.
- Academic Unit
- Oral Pathology, Radiology and Medicine
- Record Identifier
- 9984647354802771
Metrics
4 Record Views