Influence of Artificial Arch Length on Masticatory Performance in Kennedy Class II Edentulous Patients

Objectives: The objective of study was to investigate influence of artificial arch length of distal extension removable partial denture (RPD) on masticatory performance in Kennedy Class II partially edentulous patients. Methods: Eight patients (3 males and 5 females, aged 45-68 years) who missed unilateral mandibular first and second molars participated in the study. Light curing composite resin was used to make artificial arch on the denture base directly in the mouth. The anteroposterior length of artificial arch that was measured from the distal end of second premolar abutment to the distal end of artificial second molar was changed as follows. The first one (A) was adjusted so that the distal end of the arch accorded with the distal end of opposite maxillary second molar (mean 21.8 mm, ranged from 19.0 to 25.0mm). Next, the length was shortened successively by trimming the distal end of the artificial arch to 15mm (B) and 10mm (C). Masticatory performance was evaluated at each length of the artificial arch. Subjects were asked to chew two-colored wax cubes. The color mixing ratio and the deformation of the chewed cubes were measured automatically by using image analyzer (LUZEX-FS® , Nireko Co.,Tokyo). Mixing Ability Index (MAI) of chewed test foods were obtained from the data. Results: The results of Tukey test for pairwise comparisons were no significant difference (p=0.53) between A (MAI; 1.27±0.29) and B (MAI; 1.36±0.29), but significant difference (p=0.002) between B and C (MAI; 0.89±0.30). Conclusions:The length of the artificial arch in distal extension RPD influenced on masticatory performance. The masticatory performance decreased when the length the of artificial arch is shorter than 15 mm.