Purpose: To establish ideal occlusal contacts for fixed prostheses, the relationship between masticatory efficiency and occlusal contacts in dentulous adults should be investigated using suitable experimental foods. In this study, masticatory efficiency, especially fragmentation ability at the early stage of mastication, in healthy adults was evaluated using dried raisins that deform before fragmentating it at an early stage of mastication. In addition, the influence of occlusal conditions on masticatory efficiency was investigated.

Material and Methods: The subjects were 16 healthy volunteers (men: 11, women: 5), and their ages ranged between 25 and 61 years (mean ± standard deviation: 38.8 ± 10.50 years). The subject’s habitual masticatory side was determined by observing the translation of a raisin from the center of the tongue dorsum. The testing food was dried raisins, which can withstand high strain before crack propagation, and subsequently fragmentation begins. The number of chews, when fragmentation of raisin was observed, was recorded as a fragmentation ability index. The images of the occlusal records in intercuspal position were analyzed using the silicone black technique. Occlusal condition in molar regions was evaluated by the following three parameters, which were defined by the interocclusal distance: number of contacts, 0-50 μm thickness; tight contact areas: 0-50 μm thickness; and intermediate contact areas: 50-100 μm thickness. The points of inquiry were as follows: 1. fragmentation ability index, 2. number of contacts, 3. tight contact area, and 4. intermediate contact area. The data were analyzed with a Spearman’s test.

Result: There was a negative correlation between the fragmentation ability index and contact areas: tight contact areas: r=−. 433, p=. 013 and intermediate contact areas: r=−. 608, p=. 000. In addition, the fragmentation ability index was negatively correlated with the number of contacts (r=−. 481, p=. 005).

Conclusion: The results of this study indicate that our method has the potential to evaluate masticatory efficiency in dentulous adults.