Masahiro Arita

Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided.

Evaluation of Tongue Movement Function and the Effect of Tongue Movement Exercise

The purpose of this study was to evaluate differences in tongue movement function between young and elderly subjects . We developed a tongue −movement measuring device and which was used with 3 young subjects and 3 elderly subjects to measure the duratiQn of two types of tasks (anteroposterior and lateral movements ). In bQth movements , the duration measured for elderly subjects pro▽ed to be longer than that for young subjects . In both groups , the duration Df the first trial of each task was longer than that of the second or the third triaL These results suggested that tongue movement functionality for elderly subjects was lQwer than that for young subjects , and tongue movement function was improved by repeating the sarne task, Key words : Tongue movement function/Elderly/Movernent exercise 工工 一leotronio ibra y Kyushu Dental Society NII-Electronic Library Service yushu ental o iety 一 154 一 九州歯会誌 第 60巻第 6号 20G7 抄 録 高齢化社会 お い て 摂食 ・嚥 F障害 へ の 対応 は重要な課題 で あ る.今 回,舌運動機能を 評価 する方法 と して 舌運動機能測定器を試作 し , 検査 者が指示 した タ ス ク (左右運動お よび前後運動)を各被験者 に 行わせ ,こ れ に要す る時間に っ い て 若年者群 お よび高齢者群問で 比較す る こ と に よ り,両者間 にお け る 舌運動機能 の 相違 に っ い て 評価 した.また,同一 タ ス クを繰 り返 す こ とに よ る学習効果 に つ い て も両群 間 の 比較を行 っ た と こ ろ,呈示 した舌運 動に 要す る平均時間 は高齢者群が若年者群 よ りも長 く, 同 一 運 動を繰 り返す こ と に よ り , 各被験者 に学習効果 が認 め られ,各 タ ス ク の 所用時間が 短縮 さ れ る こ とが わ か っ た. キ ー ワ ー ド: 琶運 動機能/高齢者/学習効果

A Clinical Evaluation of the Reinforced Polycarbonate Denture Constructed by Compression Molding (Sumipuroi Denture System).

One hundred thirty-four dentures with reinforced polycarbonate resin (PC), utilizing a compression molding method called the Sumipuroi Denture System, were inserted into 82 partially or completely edentulous patients at the clinic of Kyushyu Dental College. Continuous clinical observation of the dentures was conducted from approximately four months to two yesrs after insertion.The results were as follows:1. No fractures or stress cracks were found in the denture bases except for one denture base which had been repaired with auto-polymerized acrylic resin at the first insertion.2. Artificial tooth loss was seen in 6 cases, which were all plastic anterior teeth with high wear resistance. Stain penetration into the interfaces between the plastic teeth and the PC denture base was also seen in some cases.3. Not a single tooth fell from the denture bases because the PC denture base had excellent adhesion to conventional acrylic resin teeth even without the creation of mechanical retentive shapes and/or the use of any chemical bonding agents on the teeth.4. No troubles due to shrinkage of denture base and dimensional change of artificial teeth caused by the molding of the PC denture was found during clinical observation.

Effects of partial denture clasp assembly on abutment tooth movement. Part 1. Movements of mesial abutment tooth in tooth-supported segment on kennedy class II modification 1 simulation model.

The excellent success through many implant systems such as the osseointegrated and others have been directed toward reducing the interest and research effort for removable prosthesis over the past few years.The need to improve the quality of removable partial dentures through research, however, will remain at a high level because the implant procedures will never eliminate removable prosthodontics at an early date.The research for the removable prosthesis, especially the movement of the abutment tooth, has been investigated in various ways such as by strain gauge, photoelastic and finite element methods, including a few experiment executedin vivo. All of them, however, have disadvantages respectively, so more effective methods for observation of the abutment tooth behaviors have been waiting for.Authors have undertaken some experiments on the abutment teeth behaviors under loading by a new analysing method that combined with MKG to the Frechettes method.This study was to analyse and evaluate the movements of the mesial abutment tooth in the tooth-supported segment on Kennedy Class II Modification 1 simulation model by the same method.The results were as follows;1. As the constructred factors were reduced from the original design of the RPD, the abutment tooth movements increased gradually.2. The greatest movements were recognized under the lingual load, and the minimum ones under the vertical load.3. Few movements toward the mesial direction were observed in every design.4. Movements toward the linguo-distal direction were remarkably noticed on almost designs.