Are bioresorbable polylactate devices comparable to titanium devices for stabilizing Le Fort I advancement?

Abstract

The purpose of this study was to evaluate whether skeletal and dental outcomes following Le Fort I surgery differed when stabilization was performed with polylactate bioresorbable devices or titanium devices. Fifty-seven patients with preoperative records and at least 1 year postoperative records were identified and grouped according to the stabilization method. All cephalometric X-rays were traced and digitized by a single operator. Analysis of covariance was used to compare the postsurgical change between the two stabilization methods. Twenty-seven patients received bioresorbable devices (group R), while 30 received titanium devices (group M). There were no statistically significant differences between the two groups with respect to gender, race/ethnicity, age, or dental and skeletal movements during surgery. Subtle postsurgical differences were noted, but were not statistically significant. Stabilization of Le Fort I advancement with polylactate bioresorbable and titanium devices produced similar clinical outcomes at 1 year following surgery.

Since Obwegeser’s description of the use of Le Fort I advancement to improve midface deficiency, the procedure has been adopted by many surgeons. In the hierarchy of stability, the operation ranks high for maintaining maxillary projection. Vertical instability is commonly associated with the procedure, especially when the maxilla is advanced and inferiorly displaced. This vertical instability is caused by stretching of the muscles of mastication, as occurs when the mandibular angle and ramus are rotated downward and backward. The vertical relapse occurs short-term and is minimal at 6 months postsurgery. When the maxilla is moved superiorly as well as anteriorly, vertical stability is more predictable.

Prior to the availability of bone plates and screws, Le Fort I osteotomy was stabilized with wire fixation alone and/or in combination with bone grafts and intermaxillary fixation. Once miniplates became commercially available, most surgeons quickly adopted them for stabilizing maxillary advancement, primarily because of the elimination of the need for intermaxillary fixation.

Bioresorbable materials are not new, but polylactate bioresorbable bone plates and screws have been commercially available in the USA for only the past 12 years. Multiple studies have been published reporting the use of these materials in the facial skeleton and their benefits, especially with orthognathic surgery. Several studies have demonstrated good stability when they have been used to stabilize mandibular osteotomies, but fewer studies are available demonstrating acceptable stability with their use for stabilizing maxillary osteotomies. No studies have compared the stability of maxillary advancement via Le Fort I osteotomy over time when stabilized with polylactate bioresorbable versus titanium devices.

The purpose of this study was to analyze the stability of Le Fort I advancement at 1 year postsurgery comparing polylactate (PLLDL 70/30) and titanium devices.

Materials and methods

Fifty-seven patients who had undergone isolated maxillary advancement with at least 1 year of follow-up between the years 2000 and 2010 were identified in the university dentofacial database. This retrospective study was approved by the biomedical institutional review board. Patients with craniofacial, traumatic, or pathological etiologies were excluded from the study, as were those who did not have preoperative, immediate postoperative, and at least 1 year postoperative cephalometric radiographs. Twenty-seven patients underwent isolated maxillary advancement and each was stabilized with four bioresorbable plates and screws (group R). Thirty patients were identified who underwent a similar operation but were stabilized with titanium bone plates and screws (group M).

The bioresorbable material used was polylactate PLLDL (70/30) 2-mm plates and screws that were manufactured either by injection moulding or extrusion. They were provided by two vendors, Inion CPS (Tampere, Finland) and Bionx (ConMed Linvatec, Key Largo, FL, USA). The titanium hardware used was either the 2-mm Leibinger or 2-mm Synthes titanium orthognathic system. All patients underwent presurgical and postsurgical orthodontic care. The operations were conducted at university hospitals under general anaesthesia with modified hypotension by three experienced faculty surgeons utilizing similar techniques. A traditional or high-level Le Fort I osteotomy was completed and stabilized with 2-mm bone plates and screws placed bilaterally at the piriform aperture and zygomatico-maxillary buttress. In most patients, occlusal splints were used with guiding intermaxillary elastics for 6 weeks postsurgery.

All cephalograms were obtained in identical format and were traced and digitized by the same technician using the University of North Carolina digitized model. The technique, reliability, and reproducibility of the method have been published previously. The principal outcome variables considered most important clinically were the changes in maxillary forward movement from immediately postsurgery to follow-up. Analysis of covariance was used to compare the postsurgical change between the two stabilization methods.

Stabilization method was the primary explanatory variable; the postsurgical position was included as a covariate as well as the interaction term with the stabilization method. Demographic characteristics (sex, race) and clinical covariates of interest (use of bone grafts, segmentation of the maxilla) were compared between the two stabilization methods using Fisher’s exact test. Age at surgery and the amount of surgical change were compared using unpaired t -tests. The level of significance was set at 0.05.

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Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Are bioresorbable polylactate devices comparable to titanium devices for stabilizing Le Fort I advancement?
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