DENTURE MOBILITY MEASURING SYSTEM OF COMPLETE DENTURES USING FOUR INFRARED VIDEO 
CAMERAS 
K.MIYASHITA, T.SEKITA, S. MINAKUCHI, Y.HIRANO, K.KOBAYASHI and M. NAGAO 
Department of Geriatric Dentistry, Faculty of Dentistry, Tokyo Medical and Dental University 
1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan 113 
E.mail : k. miyashita.gero(g)dent.tmd.ac.jp 
Tel : +81-3-5803-5561 Fax : +81-3-5803-0208 
Commission V, Working Group 3 
KEY WORDS: Biometrics, Measurement, Three-dimensional, 3-D denture movement 
ABSTRACT 
The purpose of this study was 1) to assemble and verify the system to measure simultaneously the mobility of the upper and lower 
complete denture and the movement of the mandible, and 2) to analyze the relation between denture movements and the path of 
closure of the lower jaw during functions. A three-dimensional motion capture system with four infrared TV cameras was used. 
Twelve targets with infrared rays reflecting membrane were prepared for each subject. Three of them were attached to the rim of 
eyeglasses for the calibration of head movements, six of them were placed on the labial surface of the incisal tooth of each denture 
with a resin crutch, and others were on the metal frame attached to the mandible. The direction and range of denture movements 
were calculated from movements of each three targets. The relation between lower dentures and the mandibular movements were 
analyzed with the change of the inner product of normal vectors of denture occlusal planes and mandibular planes because of the 
calibration of the mandibular movements from lower denture movements. The mandibular movements could be classified into two 
types. One (80.0%) was the type of normal stroke (the path of closure was on ipsilateral side of mastication : IS) and the other 
(20.0%) was reversed (the path of closure was on contralateral side : CS). The results are followed: This system could measure the 
denture mobility within 0.3 mm errors. Upper dentures moved toward the nonworking side in a case of IS (85.6%), and toward the 
working side in a case of CS (86.4%). The lower dentures moved and inclined toward mastication side (71.8%). The mobility of 
upper dentures had a correlation to the mandibular movement regardless of working side or nonworking side, and lower dentures to 
the bolus on the occlusal table. 
1. INTRODUCTION 2. MEASURING SYSTEM 
Edentulous persons wear complete dentures on the 2.1 System Arrangements 
compressible and movable oral mucosa. Dentures move three 
dimensionally(3-D) during normal functions, such as chewing, The measuring system for denture mobility consists of an 
swallowing and pronouncing. A decrease in denture optical motion capture system with four infrared TV cameras 
movements have an advantage effect on the maintenance of the (Elite System, Bioengineering Technology & Systems Co., 
retention and stability of dentures, and the rehabilitation of the Italy), stereo photogrammetry system(PGman, the Japan 
functions. And then the patients can convalesce more Society of Photogrammetry and Remote Sensing) with two 35 
satisfactorily. In this respect, we believe that it is very useful mm SLD cameras (NIKON F3, Nikon Co., Japan) and 
for the evaluation of prosthodontic treatments to measure 3-D analyzing computer(Optiplex XMT 590, Dell Co.). Four TV 
denture movements. Though in many studies they measured cameras were placed stereographically for 3-D measurement of 
movements of only upper complete denture, in few studies dentures and the mandibular movements(Fig. 1,2). 
measured those of the lower ones against the mandible which 
moves itself during mastication and has very flexible skin so it 
is difficult to set datum points on it. 
The purpose of this study was 1) to assemble and verify the 
system to measure simultaneously the 3-D movements of the 
upper and lower complete dentures and the mandible, and 2) to 
analyze the relation between denture movements and the path 
of closure of the mandible during functions. 
368 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996 
  
NIKON 
F3 
Denture 
  
  
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