Cup Shaped Wear Defects: More Than an Erosive Challenge?

Objectives: Objectives: It is still unclear how cup shaped defects arise in the natural dentition. These defects, often referred to as ‘cupping’, have been associated with both dental erosion and with abrasion. We applied a novel wear simulator enabling a combined mechanical and erosive loading of extracted human molars, simulating the chewing process, with the aim to create cup-shaped defects in vitro and to evaluate the contribution of both erosive and abrasive challenges in the formation of cup shaped defects.
Methods: Methods: This wear simulation in this study was performed using a Rub&Roll apparatus, in which samples are mounted in a rotating cylinder, immersed in solution, and exposed to cyclic loading. 24 extracted human molar teeth (n=8 per group) were exposed to an acidic aqueous solution at pH=4.8 combined with a variable mechanical loading: either no load (0N), 30N or 50N. Before and after 3 months continuous loading in the Rub&Roll, equivalent to roughly 1.500.000 cycles, the samples were scanned using a non-contact profilometer. The mean height loss (µm) was calculated And the teeth were examined with a SEM microscope to study surface morphology of the worn surfaces.
Results: Results: Mean surface height loss on the occlusal surface was: 0N-group:135±20 µm; 30N-group: 172±37 µm; and 50N-group: 266±100 µm were analyzed by Student t-test and all statistically significant different (p≤0.05). The erosive wear WITH the mechanical loading, especially the 50N-group, resulted in cup shaped lesions on the occlusal cusps resembling the clinical phenomenon associated with erosive tooth wear called “cupping” .
Conclusions: Conclusion: The occlusal morphology that was created in the experiment with the mechanical loading in an erosive environment was very similar to the clinical presentation of cupping wear, confirming the clinical relevance of the model. Our results indicate that both erosive and abrasive processes are involved in the occurrence of cup shaped defects.