[Study on abutment movement of distal removable dentures retained by attachments].

PURPOSE: To study the influence on the abutment movement with three kinds of precision attachments designed for distal-extension removable partial dentures (RPDs).

METHODS: Snap attachment, Ceka attachment, Mini-SG attachment were used to retain RPDs. Then food chip was masticated between the upper and lower dentitions on the attachments side. Placement of abutment was measured by LB-72 high-sensitive-laser-traneferring-detector and the data were statistically analyzed for random block analysis of variance.

RESULTS: The displacement, inclination, and torsion of the abutment movements in the mesial-distal, bucco-lingual and occluso-gingival directions all had statistical significance (P<0.05). The largest mesial-distal inclination occurred with the Mini-SG attachment. The Ceka attachment produced more abutment displacement in mesial distal and apical directions. Occlusal displacement and anti-clockwise rotation were the least with the Snap attachment.

CONCLUSION: The most equitable distribution of stresses on the supporting structures was achieved by Snap attachment with its resilent assemble, Ceka attachment transfers most of the loading forces to the abutments, Mini-SG attachment can not reduce the excessive torque applied to the abutments effectively.