The influence of single molar crown placement on the smoothness of masticatory movement.
The jerk-cost is an index that can quantify the smoothness of various movements including human body movements. A previous study reported the usefulness of jerk-cost in the evaluation of masticatory movement, and proposed that the masticatory movement of subjects with good occlusion could be explained as a maximum smooth movement. The purpose of this study was to investigate the influence of a single prosthetic molar restoration on the smoothness of masticatory movement. Fourteen adults who visited this hospital seeking a single prosthetic restoration on a molar were selected. Each subject chewed a piece of chewing gum on the molars of the treated side before and after crown placement. Movement trajectory was recorded using the Sirognathograph Analyzing System. Normalized jerk-cost (NJC) was calculated on the closing phase of each chewing cycle and was compared before and after the crown placement. After the prosthetic restoration, NJC significantly decreased (P < 0.05) in seven subjects with a crown placed on a lower molar, whereas significant changes were not observed in seven subjects with a crown placed on an upper molar. These results suggest that restoring a crown on a lower molar could significantly improve the smoothness of masticatory movement on the same side.
Watamoto
T
T
Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan. watamoto@dent.osaka-u.ac.jp
Mizumori
T
T
Egusa
H
H
Yashiro
K
K
Takada
K
K
Yatani
H
H
D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007568:Jaw / Q000502:physiology*; D008297:Male; D008409:Mastication / Q000502:physiology*; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D008963:Molar; D009068:Movement / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D019228:Tooth Crown