Measurements of hardness and erosion of enamel at increasing depths.

Faber, J.E.L. (2015) Measurements of hardness and erosion of enamel at increasing depths. thesis, Dentistry.

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Abstract

Background. The prevalence of erosive wear, especially among youngsters, is growing. Erosive wear is often the result of erosion in combination with abrasion and/or attrition. An erosive attack causes a softened top layer of enamel that is more vulnerable to wear. Research has shown that wear of eroded enamel increases with lower enamel hardness. The hardness of enamel is dependent on local chemistry and 3D composition, it varies over different parts of the enamel crown and decreases from the enamel surface inwards. The main objective of this study is to find out if erosion and erosive wear could be self-accelerating phenomena. Materials and methods. Specimens were derived from 10 extracted third molars. Three test groups were formed, each containing one specimen of each molar. In the first group Vickers hardness tests and scratch tests were performed at increasing enamel depths until 1 mm subsurface. In the second and third testgroup additional erosive treatment was performed with 50 mM citric acid solution and apple juice respectively. The acquired results were processed using Excel and statistical analysis was performed using SPSS. The results of enamel hardness and erosion depth were analysed by means of One-way ANOVA statistical tests followed by a post-hoc Tukey test and linear regression. The scratch tests were analysed by means of linear regression, One-way ANOVA and a Pearson’s correlation. The relation between enamel hardness and erosion depth was analysed by means of One-way ANOVA with a post-hoc Tukey test and a Pearson’s correlation. For all statistical tests p < 0,05. Results. The hardness tests showed a significant decrease of enamel hardness with increasing enamel depth on both sound enamel, from 3,85 GPa (± 0,17) to 2,99 GPa (± 0,16), and eroded enamel; after treatment with citric acid from 2,45 GPa (± 0,26) to 1,98 GPa (± 0,20) and after treatment with apple juice from 2,69 GPa (± 0,20) to 2,10 GPa (±0,24). On sound enamel the decrease in hardness was quite linear, R2 being 0,69. The difference in hardness between sound and eroded enamel decreased significantly with increasing depth, there was however no significant difference in relative hardness loss after erosive treatment between enamel depths. The scratch test did not yield useful data on the softened toplayer of enamel and did not show a significant difference at different enamel depths. The erosion tests showed a significant increase of erosion depth with increasing enamel depth; after treatment with citric acid from 4,8 μm (± 1,2) to 9,7 μm (± 1,2) and after treatment with apple juice from 1,8 μm (± 0,7) to 2,9 μm (± 1,2). After treatment with citric acid a significant increase in erosion depth was observed with decreasing hardness, from 5,14 μm (± 1,46) to 8,53 μm (± 1,90), and a significant negative correlation of -0,54 was found between sound enamel hardness and erosion depth. A significant negative correlation of -0,27 between sound enamel hardness and erosion depth was observed after treatment with apple juice. Discussion and conclusion. Hardness values of both sound and eroded enamel decrease significantly with increasing enamel depth. The relative hardness loss after an erosive challenge remains the same with increasing enamel depth. Erosion depth increases significantly with increasing enamel depth. It appears that dental erosion and erosive wear are self-accelerating phenomena. Further research is required to validate these findings in vivo.

Item Type:	Thesis (Thesis)
Supervisor name:	Hoogmoed, C.G. van and Sharma, P.K.
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:49
Last Modified:	25 Jun 2020 10:49
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/1017

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