Vibratory properties of maxillary dentition in maxillectomy patients wearing metal framework obturator prostheses with three different metal materials.
OBJECTIVE
The purpose of this study was to evaluate the vibratory properties of maxillary dentition in maxillectomy patients wearing metal framework obturator prostheses with three different material types of metal frameworks and to determine the optimal type by applying in vivo modal analysis.


METHODS
The three metal framework obturator prostheses using gold alloy, cobalt-chromium alloy and titanium alloy were fabricated for four maxillectomy patients, whose shapes were almost the same for each patient. All patients were classified into Aramany's Class II. The transfer functions of the maxillary dentition with and without obturator prostheses were measured to obtain the natural frequency, modal shape and damping ratio. A forced response simulation was carried out, in which an impact assuming occlusal force was applied to the lateral segment teeth on the non-defect side, and the maximum displacements of the measurement points were calculated.


RESULTS
As for the natural frequency, wearing the obturator prostheses caused reduction of the natural frequency of the maxillary dentition. The modal shapes of titanium alloy obturator prostheses showed the strongest splint-like effect and were concluded to be the most preferable. The damping ratio of titanium alloy obturator prostheses was significantly higher than cobalt-chromium obturator prostheses. The maximum displacement of gold alloy obturator prostheses was significantly the highest of all.


CONCLUSIONS
From the viewpoint of preserving abutments and remaining teeth, we conclude that titanium alloy is a more preferable material than gold alloy and cobalt-chromium alloy for the metal frameworks of metal framework obturator prostheses.
Tokyo Medical and Dental University, Faculty of Dentistry, Department of Maxillofacial Prosthetics, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. hosimfp@tmd.ac.jp
Taiji
T
Hoshiai
Toshiaki
T
Iida
Hisashi
H
Taniguchi
D002858:Chromium Alloys; D003722:Dental Alloys; D003817:Dentition; D005260:Female; D006047:Gold Alloys; D006801:Humans; D008297:Male; D008437:Maxilla / Q000503:physiopathology* / Q000601:surgery*; D008875:Middle Aged; D010158:Palatal Obturators; D014025:Titanium; D014732:Vibration
D002858:Chromium Alloys; D003722:Dental Alloys; D006047:Gold Alloys; D014025:Titanium