Method:
Seventeen SDA subjects (65.1±10.2 y) with 29 SDA sides, and 18 subjects (23.1±3.0 y) with complete dentitions participated in this study. 29 SDA sides were classified into 3 classes according to the degree of occlusal units in molar region (no missing, only the second molar missing, the first and second molars missing, the molars and the second premolar missing) and compared with normal dentitions.
Subjects were instructed to chew the chewing gum containing wax particles (φ300μm) 25 times for each side. After expectoration, the gum was softened in hot water and pressed between clear plastic plates to 300μm. A photograph was taken by infrared camera and the number of original particles (neither crushed nor grinded) was counted. Then, crushing rate for 1 time mastication was calculated and defined as compressive value (CV). Statistical analysis was performed with the T-test (p< 0.05).
Result:
The CV of complete dentition, only the second molar missing, the first and second molars missing and the molars and the second premolar missing were 1.58±0.50, 0.98±0.51, 0.97±0.44 and 0.98±0.51 respectively.
All SDA sides were significantly lower than normal sides in normal dentitions (p<0.05). However, the significant differences were not shown among the SDA sides.
Conclusion: Only one molar missing influences masticatory performance. However, the fact that significant difference could not be seen among the type of SDA might indicate that adaption after missing molars was related with masticatory performance in SDA patients.