title: Evaluation of post-surgical relapse in maxillary surgery using resorbable plate.
abstract: 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.
  
  
  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.
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea.
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Kim
authors.forename: Chung-Kyu
authors.initials: CK
authors.lastname: Yoo
authors.forename: Pil-Young
authors.initials: PY
authors.lastname: Yun
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Baek
authors.forename: Young-Kyun
authors.initials: YK
authors.lastname: Kim
mesh_terms: D020341:Absorbable Implants; D001672:Biocompatible Materials / Q000737:chemistry; D001860:Bone Plates; D002508:Cephalometry / Q000379:methods; D004146:Dioxanes / Q000737:chemistry; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry; D008297:Male; D008334:Mandible / Q000473:pathology / Q000601:surgery; D008437:Maxilla / Q000473:pathology / Q000601:surgery*; D009295:Nasal Bone / Q000473:pathology; D019340:Osteotomy, Le Fort; D059229:Osteotomy, Sagittal Split Ramus; D010159:Palate / Q000473:pathology; D011091:Polyesters; D011108:Polymers / Q000737:chemistry; D012008:Recurrence; D012658:Sella Turcica / Q000473:pathology; D014716:Vertical Dimension; D055815:Young Adult
chemical_list: D001672:Biocompatible Materials; D004146:Dioxanes; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C443643:trimethylene carbonate; C033616:poly(lactide)