[Effect of differences in guide plane configuration on abutment tooth displacement during clasp insertion]

Three types of guide plane were compared to clarify the effect of guide plane setting conditions on abutment displacement which arises when an Akers clasp is inserted.

An experimental model with an artificial periodontal membrane made of hydrophilic vinyl polysiloxane impression material was created. Abutments given a guide plane with only a clasp body (G1), a guide plane whose span extended as far as the reciprocal clasp arm shoulder region diametrically opposite the retention area (G2), and a guide plane for the entire reciprocal clasp arm region (G3) were created, and an Akers clasp was made for each abutment. The amount of abutment displacement and the degree of rotation that arose in the abutment when the Akers clasp was inserted were detected with three laser displacement sensors for comparison.

The amount of abutment displacement that arose when the clasp was inserted was higher with G1 than with G2 and G3 in the lingual and distal directions, and no difference was seen between G2 and G3. It was lower with G1 than with G2 and G3 in the buccal direction, and no difference was seen between G2 and G3. It was high with G1 in the mesial direction, and the abutment rotation was high, whereas they were low in the case of G3. A difference was seen between each condition.

Differences in guide plane setting conditions affected the abutment displacement that arose when an Akers clasp was inserted, suggesting that a difference in reciprocal action is seen depending on the setting conditions of the guide plane.