Evaluation of post-surgical relapse in maxillary surgery using resorbable plate.

BACKGROUND

This study was carried out to evaluate the vertical and horizontal changes after maxillary surgery using resorbable plates made of an l-lactic acid and d-lactic acid copolymer of PLA (P(L/DL)LA), and to analyze factors of skeletal pattern and surgical movement affecting the post-surgical change.

MATERIALS AND METHODS

The subjects consisted of 20 patients who underwent bimaxillary surgery using P(L/DL)LA resorbable plate (Inion CPS, Inion Ltd., Tampere, Finland). Lateral cephalograms were taken at 1 month before (T0), 1 month after (T1) and 6 months after surgery (T2). They were divided into two groups, one showing less relapse (LR) and one more relapse (MR) using K-means clustering analysis of post-surgical relapse (T2-T1). In terms of linear and angular variables of maxillary relapse, the two groups were compared with measurements at the pre-surgical stage (T0), the surgical change obtained (T1-T0) and post-surgical relapse (T2-T1) using Mann-Whitney test.

RESULTS

Because Frankfort horizontal (FH) to anterior nasal spine (ANS) showed the largest variance in post-surgical relapse of the maxilla, it was used for clustering analysis to define the MR and LR groups. Comparison between the MR and LR groups showed that a short preoperative anterior facial height (AFH) was a significant factor in maxillary relapse. The AFH of the MR group was significantly shorter pre-surgically (p<0.01) and was significantly increased postoperatively (p<0.05) when compared to the LR group. In post-surgical relapse, AFH, FH to A, FH to ANS and the palatal plane angle of the MR group were significantly decreased.

CONCLUSIONS

In the case of a short AFH, P(L/DL)LA resorbable plates may not provide enough vertical stability in the maxillary position due to the muscle force. Facial height might be an important factor when deciding to use P(L/DL)LA resorbable plates for maxillary surgery.