義歯装着後の咬合応力による下顎後方義歯の粘膜の塑性変形に関する実験的研究

[Experimental study on the plastic deformation of underlying mucosa in lower posterior denture caused by occlusal stress after denture wearing].

抄録

生まれつきの粘膜を含む可撤式義歯の治療においては，粘膜の変形を十分に考慮した上で咬合を確保することが必要である．つまり，義歯装着後の下層軟組織の塑性変形を明らかにすることが必要である．そこで，下層軟組織の支持圧の違いによる影響を評価する目的で，義歯挿入後の組織表面の経時的変化を観察した．また，義歯底面とその下の軟組織表面との間に特殊な条件の非圧迫域を設定し，この非圧迫域に義歯を挿入することにより，義歯底面と軟組織表面との間の圧力の差を測定した．下顎後方部に欠損を有する20名の被験者に対して，底面に円筒形の非圧迫性空洞（直径3 mm，深さ2 mm）を有する可撤式自由端義歯を作製した．その位置は，第一大臼歯遠位部に相当する中遠位部，歯槽堤，歯槽堤と頬側義歯境界の中間部，歯槽堤と舌側義歯境界の中間部の3箇所であった．義歯装着開始後，一定日数経過後に被験者の顎から印象採得を行った．100個の顎模型で非圧迫部の輪郭を測定した．結果1.非圧迫部粘膜の腫脹 1) 非圧迫部粘膜の腫脹高さの経時的変化により以下の5タイプに分類される．S-1 型：義歯装着後 3 日以内に腫脹高が著明に増加し、装着後 30 日目まで腫脹高に実質的な変化がない。タイプS-2：義歯装着後3日以内に著しい腫脹高の増加が認められ、装着後30日目まで腫脹高の増加が持続する。Type S-3：義歯装着後3日以内に腫脹高さの顕著な増加が見られたが、装着後30日目まで腫脹高さの減少が続いた。G型：義歯装着後3日以内の腫脹高さの増加は比較的小さいが、装着後30日目まで腫脹高さが増加した。Type N：装着後30日目まで腫脹高の増加は認められなかった。2）タイプ別にみた各部位の腫脹高さと頻度（400字未満要約）

In the treatment of removable dentures including mucosa born, it is essential to secure the occlusion based on adequate consideration of deformation of mucous membrane. This means that it is necessary to clarify the plastic deformation of underlying soft tissues after denture insertion. With the objective of assessing the influence of the difference in the supporting pressure of the underlying soft tissues, the longitudinal changes of the tissue surface after insertion of denture were observed. The non-pressure areas with special conditions were established between the basal surface of the dentures and the surface of the underlying soft tissues. Removable free end dentures with cylindrical non-pressure cavity (3 mm in diameter and 2 mm in depth) in the basal surface were prepared for 20 subjects having a missing of lower posterior region. Such three non-pressure cavities were positioned in the following locations: in a mesio-distal location corresponding to the distal region of the first molar, at the alveolar crest, at a location halfway between the alveolar crest and the buccal denture border, and a location halfway between the alveolar crest and the lingual denture border. Impressions were taken from the subjects' jaws after the fixed numbers of days following initiation of denture wearing. Contours of the non-pressure areas were measured in 100 jaw models. Results. 1. Swelling of the mucous membrane of the non-pressure area 1) Subjects are classified into the following 5 types on the bases of longitudinal changes in the swelling height of the mucous membrane in the non-pressure area. Type S-1: Marked increase in swelling height observed within the first 3 days after insertion of dentures, but practically no change in swelling height until the 30th post installation day. Type S-2: Marked increase in swelling height observed within the first 3 days after insertion of dentures, and swelling height increased continuously until the 30th post installation day. Type S-3: Marked increase in swelling height observed within the first 3 days after insertion of dentures, but swelling height decreased continuously until the 30th post-installation day. Type G: Increase in swelling height comparatively small within the first 3 days after insertion of dentures, but swelling height increased until the 30th post-installation day. Type N: No increase in swelling height observed until the 30th post-installation day. 2) Swelling height and frequency in each location according to type.(ABSTRACT TRUNCATED AT 400 WORDS)