There is a few investigations on the conditions of males, females with OPA attachments and abutment teeth. The subjects were 103 cases followed up for about these seven years, including 192 abutments with OPA attachments which have been applied to the few remaining teeth in overlay dentures and removable partial dentures. Methods
1) Male parts were observed on the Standarized photograph.
2) Female parts with O'ring rubber were observed by taking apart from the denture.
3) Abutment teeth were investigated about the X-ray photograph, tooth movility, pocket and infiamation of the marginal gingiva.
Conclusion
1) Only 5.2 % of 192 abutments were extracted, but other cases followed-up examinations have been in almost good conditions.
2) The proportion of the female parts of dentures that had fractured was 28.80 of resin-based dentures and 18.3 % of metal-based dentures.
3) On the almost casting males except neck part two types abrasion by denture resin have been observed.
4) On the lower part of O'ring rubber the five types wears have been observed, while on the upper part very little abrasion.
5) The proportion of enlargement of inner diameter of O'ring rubber was 39.2 0. The enlargement was often seen in bucco-lingual direction.
6) A highly significant correlationship between the enlargement of inner diameter of O'ring rubber and denture movement was seen.
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