Schipper, L.A. (2014) Breuksterkte van lithium disilicaat en composiet endokronen bij laterale belasting. Een in vitro studie. thesis, Dentistry.
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Abstract
When endodontically treated teeth are extensive restored often there is a lot of coronal loss. To prevent recontamination of the root canal system and/or peri-apical space, restore function and morphology, it is important to restore the teeth after endodontically treatment. The endocrown is an adhesive bonded monolithic restoration, that uses the intracoronale space for retention. This space acts like an intern ferrule. The goal of this in vitro study was to compare the fracture resistance and mode of failure of untreated third molars and endocrowns made of two different materials. The null hypothesis was that the fracture strength and failure mode would not differ significantly. Material and methods Thirty extracted sound mandibular third molars were used in this study. The specimens were embedded and divided in three groups after randomization. Group 1 were the untreated specimens, and served as a control group (n=10). In group 2 the specimens were prepared and treated with an IPS e.max CAD endocrown. In group 3 the specimens were prepared and treated with an LAVA Ultimate endocrown (n=10) (n=10). Group 2 and 3 were scanned with CEREC, software 4.0 and decapitated 1mm above the CEJ and were endodontically treated. After preparation IDS was applied. With the use of CEREC the preparations were scanned and the restorations were milled according to the original morphology. The crowns were cemented with Variolink II. After placement of the crowns, all thirty specimens were thermocyled 10.000 times. The specimens were tested at a 90 degree angle to the long axis of the teeth, with the use of a static testing machine and loaded (1mm/min) until fracture occurred. The force (Newton) required for the fracture was documented in Excel. The mode of fracture was inspected visually and dived in to two categories, were the distinction between destructive and non-destructive was made. To analyze the fracture strength data the non-parametric Kruskal-Wallis test was used. After this test a post-hoc Mann-Whitney test was used with a Bonferroni correction α = 0.0167 (0.05/3). The mode of failure was analyzed with Fisher’s test. Results A significant difference was found between the groups 1,2 and 3. The test could not show a significant difference between group 1 and group 2 (U=23.5, p 0.045).. Between group 1 and 3 (U= 10, r=-0.68, p= 0.002)., and group 2 and 3 (U= 13, r=-0.63, p= 0.004) a significant difference was seen. No significant difference was observed between the failure mode and the three groups. Conclusion There is a significant difference between the group of the untreated specimens and the group restored with endocrowns of Lava Ultimate. Also was the fracture resistance of the group restored with IPS e.max CAD significant higher than the group restored with the Lava Ultimate. No significant difference of mode of failure was found. The null hypothesis was partially rejected.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Cune, Prof. Dr. M.S. and Gresnigt, Dr. M.M.M. |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:46 |
| Last Modified: | 25 Jun 2020 10:46 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/792 |
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