Kenji Warita

Accuracy of Interocclusal Recording Addition-type Silicone Rubber Impression Materials.for Reproducibility of Intercuspation.

The purpose of this study was to investigate the accuracy of interocclusal recording addition-type silicone rubber impression materials that reproduced intercuspation on mounting stone casts. A bridge type reference model, which could not maintain stable intercuspation without interocclusal records, was selected. The reference model was mounted on an articulator. Interocclusal records were taken on the reference model. The reference model could be separated from the articulator when interocclusal records were measured. For interocclusal records which were made from PRESIDENT JET BITE, EXABITE, Stat·BR, BITESIL, MEMOSIL, and MUSHPRINT between the upper and lower reference models, the occlusal heights of the reference model on the left molar of the abutment side, anterior teeth, and right molar were measured using an IP-Checker. In addition, the relationship of the reproducibility of intercuspation and the mechanical properties of materials was studied.The results were as follows:1. The occlusal height on the left molar was high; the occlusal height on the anterior teeth and the rightmolar were unchanged or low when the recording range was on the abutments. The occlusal height on the left molar and the anterior teeth were high; the occlusal height on the right molar was unchanged when the recording range was 1/3 of the dentition.2. The reproducibility of intercuspation of the interocclusal recording addition-type silicone rubber impression materials was excellent; however, MEMOSIL was inferior to the other materials. The occlusal height on the anterior teeth was greatly influenced by the recording range when BITESIL and MEMOSIL were used.3. It was surmised that the reproducibility of intercuspation was influenced by the compression set and the dimensional change of the interocclusal recording addition-type silicone rubber impression materials.

In vivo Study on the Adaptation of Full Cast Crowns.

The adaptation of crowns and bridges is a significant factor in relation to secondary caries or periodontal disease. In this study, eight premolars which would be extracted for orthodontictreatment were used to investigate in vivo adaptation of full cast crowns. The results wereas follows:1. The mean cement thickness was similar to the results of an in vitro study previouslyreported.2. All the impression methods investigated in this study were considered to be clinicallyacceptable. The individual tooth tray method was the most exact and stable of the three methods.3. In two combined impression methods, the marginal cement was thicker than that of theaxial surfaces. This tendency was more remarkable in the mesial and distal surfaces compared tothe buccal and lingual surfaces.4. Marginal cement layers of the buccal and distal surfaces were thicker than those of thelingual and mesial surfaces.

Adaptability of the cast core with silicone bite-impression technique.

得ている9,10).こ の印象法 は,印 象操作 や技工操作が簡 便であるな ど臨床的に多 くの利点 を備 えた術式であ り, 特に 口腔内 における咬頭嵌合位 の調整量 がきわめて少 な いことが あげ られ る.ま た,最 近開発 された付加 型シ リ コーンラバー印象材 は経時的寸法変化 が小 さ く,弾 性ひ ずみや永久ひずみが小 さいな ど優 れた理工学的性 質を も っため,本 術 式には最適な印象材 と考 え られる. しかし,咬 合 印象法 に関 しては臨床術式の 報 告 が 多 く,精 度的な検討 はほ とん どな され ていない、 そこで ま ず,基 礎的研究 として,シ リコー ンラバー印象材 による 咬合印象法 がキ ャス トコア製作 のための印象法 として十 分な精度をもつかを明 らかにす るために,現 在一般 に行 われている既製 トレーを用いた2重 同時 印象法および直 接法を対照 とし,そ れぞれの方法 によ り製作 したキャス トコアの適合精度を比較検討 した.