Cnossen, A.N. (2013) Micromorfologie van door amalgaam verkleurd dentine : SEM-onderzoek naar een mogelijke oorzaak van lagere hechtsterktes van composiet. thesis, Dentistry.
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Abstract
Objective In a recent study significant lower bond strengths were found for two adhesive systems to dentin that was darkly discolored by amalgam, compared to sound dentin.42 The cause of these lower bond strengths may be traced to the micromorphology of dentin that was discolored by amalgam. This research focuses on finding an explanation for the IJ.lentioned reducedJ >ond strengths of adhesive resins to dentin that was discolored by amalgam, based on the morphological features after etching, so that measures can be taken to improve the bond strength. Materials and methods To be able to analyze the icromorphological features of the test group of dentin, darkly discolored by amalgam, compared to a control group of sound dentin, both ntitatively and qualitatively, SEM recordings were made. For the test group and the control group 7 extracted molars with class I or class II amalgam restorations and 6 extracted sound third molars, all obtained from general practices, were selected at random. These molars were then modified so, that 4 research groups were formed, namely the test groups of excavated and etched discolored dentin (Group 1), next to etched discolored dentin (Group 2), and the control groups of excavated and etched sound dentin (Group 3), next to sanded and etched sound dentin (Group 4). Excavating was done by a round tungsten carbide bur and 600-grit silicon carbide paper was used for sanding. The etchant contained 35% phosphoric acid gel. Prior to SEM-research the molar teeth were fractured along a previously-applied saw cut, so per preparation both fracture and occlusal recordings could be made at different magnifications. The SEM-recordings of the different research groups were then reviewed and compared with each other on micro morphological features. The qualitative assessment was descriptive. For the quantitative assessment open, partly open and closed dentinal tubules were measured by two reviewers, blinded for each others measurements. From the measured data (average data of the reviewers) percentages open, partly open and closed dentinal tubuli were calculated. The data were analyzed using Kruskai-Wallis and Mann-Whitney U tests (significance level a of 0.05). Results When compared, micromorphological differences could be demonstrated between the groups of excavated and etched discolored dentin (Group 1) and sanded and etched sound dentin (Group 4). The excavated and etched discolored dentin (Group 3) showed more debris and more closed dentinal tubules. Only slight differences in micromorphology were found between the groups of excavated and etched discolored dentin (Group 1) and excavated and etched sound dentin (Group 3). In both groups varying degrees of debris and open dentinal tubules were found, and average group percentages for closed dentinal tubules were found to be similar. The most debris was present in the group of solely etched discolored dentin (Group 2). This was the only group showing fully debris-covered surfaces. Conclusion After operating according to an equal method, consisting of excavating and then etching, based on the found micromorphology, only little evidence was found in this study that could explain a possible significant difference in bond strength for adhesive resin to discolored versus sound dentin. Regarding the presence of lots of debris found in the group of etched discolored dentin (Group 2), excavating up to hard dentin seems necessary, while removing the granular layer -if present- at the same time. In this study excavating discolored dentin with a tungsten carbide bur showed a micromorphology of the dentin surfaces that was similar to that of excavated sound dentin. However, when discolored dentin is not excavated well enough, there is a risk of extensive presence of debris.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Juch, dr. P.J.W. and Scholtanus, drs. J.D. and Centrum voor Tandheelkunde en Mondzorgkunde van de and Rijksuniversiteit te Groningen |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:42 |
| Last Modified: | 25 Jun 2020 10:42 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/326 |
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