Resorbable PLLA-PGA screw fixation of mandibular sagittal split osteotomies.

The purpose of this study was to evaluate the intraoperative placement and clinical effectiveness of resorbable copolymeric screws for mandibular sagittal split ramus osteotomies. Thirty-seven patients who underwent bilateral sagittal split osteotomies of the mandible were fixated with three 2.5-mm copolymeric poly-L-lactic-polyglycolic (PLLA-PGA) screws on each side. No postoperative maxillomandibular fixation was applied. Twenty-five patients experienced mandibular advancement and 12 patients had setbacks. The average advancement was 6.5 mm (range, 3-17 mm) and the average set-back was 5.2 mm (range, 3-8 mm). Intraoperative placement was uncomplicated and no screws were stripped during placement. No problems in immediate postoperative stability were encountered and relapse was not evident in any patient. Follow-up ranged from 3 to 17 months. The screw holes remained evident radiographically after 1 year. Two and one-half-millimeter copolymeric PLLA-PGA resorbable screws for mandibular ramus osteotomies appear to offer clinical results comparable with metallic screw fixation.     

Biodegradable osteosynthesis in mandibular advancement: a pilot study

In this pilot study four patients are presented who underwent bilateral sagittal split osteotomies of the mandibular ramus for mandibular advancement. Biodegradable osteosyntheses were used for internal fixation. All patients were from the same dentofacial category: mandibular retrognathia with a low to normal mandibular plane angle. In two patients cylindrical self-reinforced polyglycolide (PGA) rods were used for internal fixation of the osteotomy segments. Long-term evaluation showed a complete ossification at the sites of biodegradable rods. In two other patients, self-reinforced poly(L-lactide) (PLLA) screws with a diameter of 2 mm were used to stabilize osteotomy segments. The two different techniques of osteosynthesis and the problems encountered are discussed.     

Stability of the Le Fort I osteotomy with anterior internal fixation alone: a case series.

PURPOSE: The purpose of this case series was to evaluate the late postsurgical stability of the Le Fort I osteotomy with anterior internal fixation alone and no posterior zygomaticomaxillary buttress internal fixation. PATIENTS AND METHODS: Sixty patients with maxillary vertical hyperplasia and mandibular retrognathia underwent a 1-piece Le Fort I osteotomy of the maxilla with superior repositioning and advancement or setback. A bilateral sagittal split ramus osteotomy for mandibular advancement was also performed in 22 patients. Stabilization of each maxillary osteotomy was achieved using transosseous stainless steel wires and/or 3-hole titanium miniplates in the piriform aperture region bilaterally, with no zygomaticomaxillary buttress internal fixation. (Twelve of the 60 identified patients were available for a late postoperative radiographic evaluation.) Lateral cephalometric radiographs were taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3) to analyze skeletal movement. RESULTS: These 12 patients (5 male, 7 female) had a mean age of 24.5 years at surgery. Mean time from surgery to T2 was 41.2 days; mean time from surgery to T3 was 14.8 months. One patient received anterior wire osteosynthesis fixation, while 11 patients received both anterior titanium miniplate internal skeletal fixation and anterior wire osteosynthesis fixation. Six patients underwent Le Fort I osteotomy with genioplasty, 1 patient underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy, and 5 patients underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy and genioplasty. These 12 patients all underwent maxillary superior repositioning with either advancement (11 patients) or setback (1 patient). Statistically significant surgical (T2-T1) changes were found in all variables measured. In late postsurgical measurements (T3-T2), all landmarks in the horizontal and vertical plane showed statistically significant skeletal stability. CONCLUSION: This case series suggests that anterior internal fixation alone in cases of 1-piece Le Fort I maxillary superior repositioning with advancement has good late postoperative skeletal stability.     

The fate of resorbable poly-L-lactic/polyglycolic acid (LactoSorb) bone fixation devices in orthognathic surgery.

PURPOSE: The aim of this study was to evaluate the long-term outcome of resorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) bone fixation devices used for fixation of maxillary and mandibular osteotomies. MATERIALS AND METHODS: Twelve patients were postoperatively evaluated. Eight patients who had undergone bilateral sagittal split mandibular osteotomies that had been fixed with PLLA-PGA screws were followed-up for up to 2 years postoperatively with radiographs. One of these patients underwent a bone biopsy for detailed histologic evaluation of the screw fixation sites. Two patients who had undergone mandibular symphyseal osteotomies were also radiographically evaluated at 18 months to 2 years postoperatively. Two patients who had Le Fort I osteotomies fixed with PLLA-PGA plates and screws underwent open exploration of the operated sites for visual examination. RESULTS: All 8 mandibular osteotomy patients showed radiographic screw hole lucency immediately after surgery that remained unchanged in the first year after surgery. By 18 months postoperatively, all 48 screw holes showed near or complete trabecular bone fill. The bone biopsy of one screw hole at 2 years postoperatively showed complete fill with normal trabecular bone. No residual polymer material or fibrous scar was seen. The mandibular symphyseal sites showed complete elimination of all screw holes by 2 years postoperatively, with only faint evidence of intraosseous tunnels. The maxillary sites showed complete bone healing along the osteotomies and no evidence of residual fixation material or bone defects in the screw holes. No communication with the maxillary sinus was seen in the fixation sites. CONCLUSION: This orthognathic patient series showed complete resorption of the PLLA-PGA fixation devices without osteolysis in maxillary and mandibular bone sites by 18 to 24 months after surgery.     

Biomechanical testing of resorbable screws used for mandibular sagittal split osteotomies

PURPOSE: The object of the study was to determine the suitability of specific resorbable screws for fixation of mandibular sagittal split osteotomies by in vitro biomechanical strength testing. MATERIALS AND METHODS: Resorbable screws (2.5 mm diameter) composed of a polylactic acidpolyglycolic acid copolymer were placed in an inverted L-pattern in overlapping urethane blocks representative of sagittal split mandibular surgery. In an in vitro model at room temperature, the test specimens were statically loaded until tensile failure occurred. On a different set of test specimens, dynamic testing was done in an in vitro water bath at body temperature through cyclic loads representative of mastication until failure. RESULTS: In static testing, three 2.5-mm resorbable screws sustained an average peak load of 131 Kiloponds (Kp) (standard deviation, 5.2 Kp) with 5.5% strain at yield. In dynamic testing, the resorbable screws tolerated a 45.3-Kp load for an average of 340,675 cycles (22,783 standard deviation). Several of these test specimens did not ultimately fail and were further evaluated by static testing with an average load of 77.4 Kp until fixation failure occurred. CONCLUSIONS: These laboratory results indicate a relatively high resistance to biomechanical loads representative of mastication and suggest that 2.5-mm resorbable screws of this particular polylactic acid-polyglycolic acid copolymer may be effective in fixation of the postoperative unrestrained sagittal split mandibular osteotomy.     

Comparative study of skeletal stability between bicortical resorbable and titanium screw fixation after sagittal split ramus osteotomy for mandibular prognathism

IntroductionResorbable screw fixation for orthognathic surgery is widely used in oral and maxillofacial surgery and has several advantages. However, surgeons are concerned about using resorbable screws in orthognathic surgery because of possible postoperative complications such as relapse, screw fracture, and infection. The purpose of this study was to evaluate the skeletal stability of bicortical resorbable screw fixation after sagittal split ramus osteotomies for mandibular prognathism.Materials and methodsThis study included 25 patients who underwent mandibular setback surgery fixed with resorbable screws after sagittal split osteotomy at the Department of Oral and Maxillofacial Surgery at Seoul National University Dental Hospital. Five resorbable screws (Inion CPS^®, Inion Ltd., Finland) were applied bicortically at each osteotomy site via a transbuccal approach. No rigid intermaxillary fixation was applied on the first postoperative day. Passive mouth opening exercises were allowed, using two light, rubber elastics for guidance. The control group was 25 patients fixed with four titanium screws. The follow-up period was 12–22 months (mean 17.8 months). Postoperative skeletal changes on lateral cephalometric radiographs were analyzed and compared between the two groups preoperatively, immediately postoperatively, and 6 months postoperatively.ResultsThe average setback was 6.9 mm and no major intraoperative complications occurred. One patient experienced infection immediately after surgery that was controlled uneventfully. The data did not demonstrate any significant difference in postoperative skeletal stability between the two groups. Differences between the immediate postoperative state and 6 months after surgery were not significant. In earlier cases, especially for patients with severe mandibular prognathism, immediate postoperative elastic traction was needed for stable occlusal guidance.ConclusionsThe results of this study indicate that bicortical resorbable screws offer a clinically stable outcome for the fixation of mandibular sagittal split osteotomies in mandibular prognathism. However the resorbable screws showed less stable results vertically than the titanium screws.     

Osteotomy site healing following mandibular sagittal split osteotomy and rigid fixation with polylactide biodegradable screws.

Follow-up of 47 patients, treated using mandibular bilateral sagittal split osteotomy and self-reinforced poly-L-lactide acid (SR-PLLA) screws for rigid internal fixation, is presented. The focus was on clinical and radiological osteotomy healing. The average follow-up time was 2.1 years (range 0.5-5 years). Clinical recovery and radiological osteotomy healing during follow-up were uneventful. Osteolytic changes were seen around the SR-PLLA screws in 27% of cases. The majority of the screw canals remained as radiolucent shadows without bony filling.     

Mandibular sagittal split osteotomy: is a bicortical 2-screw osteosynthesis adequate?

The aim of this study was to prospectively evaluate the accuracy and reliability of the use of the Hunsuck/Epker–type mandibular split osteotomy together with osteosynthesis with placement of 2 bicortical positioning screws without the adjunctive use of a postoperative maxilla-mandibular fixation in the treatment of mandibular dentofacial deformities. We analyzed the clinical and radiologic data of 54 patients with dentofacial deformities. We recorded age and sex, status of healing, and complications. Postsurgical complications that were recorded as minor did not require surgical intervention, whereas major complications required further surgical intervention. Fifty-one patients (94.5%) had a successful treatment outcome without complications, 13 patients (24%) developed minor complications, and 3 patients (5.5%) developed screw loosening requiring hardware removal and reosteosynthesis. The present study has demonstrated that Hunsuck/Epker–type mandibular split osteotomy together with osteosynthesis with placement of 2 bicortical positioning screws without the adjunctive use of a postoperative maxilla-mandibular fixation in the treatment of mandibular dentofacial deformities results in a low rate of major complications with a high rate of success     

Stability after surgical-orthodontic correction of skeletal Class III malocclusion. I. Mandibular setback

Postsurgical stability of mandibular setback to correct mandibular prognathism was compared for three approaches: transoral vertical ramus osteotomy, bilateral sagittal split osteotomy with wire osteosynthesis and maxillomandibular fixation, and bilateral sagittal split osteotomy with rigid internal fixation via bone screws. In the transoral vertical ramus osteotomy group, the mean postsurgical change in chin position was almost zero, but nearly 50% of the patients did have clinically significant changes in chin position; two thirds of these movements were posterior and one third anterior. In the bilateral sagittal split osteotomy groups, the chin either stayed in its immediately postsurgical position or moved anteriorly. In one fourth of the patients who received maxillomandibular fixation and in nearly half of the patients who received rigid internal fixation, the chin moved forward more than 4 mm.     

Assessment of material- and technique-related complications following sagittal split osteotomies stabilized by biodegradable polylactide screws

OBJECTIVE: The aim of this retrospective clinical study was to determine whether there are any material-related problems and increased occurrence of postoperative mandibular nerve and temporomandibular joint dysfunctions in connection with the use of biodegradable self-reinforced poly-L-lactide (SR-PLLA) screws for bone fixation after bilateral sagittal split osteotomies (BSSO). STUDY DESIGN: Forty consecutive patients who underwent BSSO and mandibular advancement that included fragment fixation using SR-PLLA screws were monitored for an average of 2.2 years postoperatively. RESULTS: The osteotomy sites healed uneventfully with no adverse reactions. The incidence of postoperative sensory disturbances of the inferior alveolar nerve was 27%. Symptoms of temporomandibular joint disorders (TMJD) observed preoperatively in 73% of patients were reduced to 48% after surgery. CONCLUSION: The occurrence of postoperative sensory disturbances and TMJD symptoms in this study did not deviate strikingly from that of other studies using conventional osteosynthesis. No specific complications related to the screw material were observed.     

Bicortical biodegradable screws for rigid fixation of traumatic sagittal split mandibular fracture

Rigid fixation is the most important issue in the bone healing process. Although internal metallic bone fixation has become increasingly popular over the past 10 years, the presence of several potential problems of metallic bone implants with the popularity of the use of biodegradable plates and screws for craniomaxillofacial fixation have increased in the last 10 years. Rigid fixation of bony fragments was achieved by bicortical applied biodegradable screws in a patient with a sagittal oblique mandibular fracture. Precise bone reduction was maintained with bicortical applied biodegradable screws in the postoperative period. The postoperative period was uneventful and the patient retained the intraoperatively achieved perfect occlusion within a 9-month follow-up period. In this particular case, the advantages of use of resorbable fixation systems are combined with the advantages of bicortical screw fixation of split osteotomy without sacrificing the stability of rigid fixation.     

Fixation of bimaxillary osteotomies with resorbable plates and screws: experience in 20 consecutive cases.

PURPOSE: This study evaluated the potential effectiveness of resorbable plate and screw fixation for skeletal stabilization of simultaneously performed maxillary and mandibular osteotomies. PATIENTS AND METHODS: Twenty consecutive patients underwent simultaneous maxillary and mandibular osteotomies that were fixed using copolymeric poly L-lactic acid/polyglycolic acid (PLLA/PGA) plates and screws. Prefabricated acrylic intermediate and final splints were used as guides and then removed at completion of the surgery. Guidance elastics were applied at 2 weeks postoperatively. RESULTS: The LeFort I osteotomies included segmentalizations with and without bone grafts (7/20), impactions (4/20), advancements (8/20), and unilateral downgrafting with a bone graft (2/20)- one of which was segmental. The mandibular sagittal split osteotomies involved advancements (11/20), setbacks (5/20), and asymmetric rotation (4/20). Three patients had simultaneous genioplasties, which were also stabilized with resorbable fixation. All maxillae were fixed with four 2.0-mm L-shaped plates and screws. The mandibular rami were maintained with three 2.5-mm bicortical screws per side. The mandibular symphyseal segments were held in position with two or three 2.5 mm bicortical screws. All surgeries were accomplished uneventfully, and no problems in the immediate postoperative stability of the occlusion were encountered. Follow-up ranged from 12 to 25 months. CONCLUSIONS: The initial clinical findings suggest that this form of bone fixation is a viable alternative to standard metallic fixation techniques for certain maxillomandibular deformities in which excessive bony movements are not performed. Differences exist in both intraoperative application and postoperative management of masticatory function. This is partially a US government work. There are no restrictions on its use.     

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: rigid versus nonrigid fixation

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation.     

Stability of skeletal class III malocclusion after combined maxillary and mandibular procedures: rigid internal fixation versus wire osteosynthesis of the mandible.

PURPOSE: The aim of this study was to evaluate skeletal stability after double-jaw surgery for correction of skeletal Class III malocclusion to assess whether there were any differences between wire and rigid fixation of the mandible. PATIENTS AND METHODS: Thirty-seven Class III patients had Le Fort I osteotomy stabilized with plate and screws for maxillary advancement. Bilateral sagittal split osteotomy for mandibular setback was stabilized with wire osteosynthesis and maxillomandibular fixation for 6 weeks in 20 patients (group 1) and with rigid internal fixation in 17 patients (group 2). Lateral cephalograms were taken before surgery, immediately after surgery, 8 weeks after surgery, and 1 year after surgery. RESULTS: Before surgery, both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary sagittal stability was excellent in both groups, and bilateral sagittal split osteotomy accounted for most of the total horizontal relapse observed. In group 1, significant correlations were found between maxillary advancement and relapse at the posterior maxilla and between mandibular setback and postoperative counterclockwise rotation of the ramus and mandibular relapse. In group 2, significant correlations were found between mandibular setback and intraoperative clockwise rotation of the ramus and between mandibular setback and postoperative counterclockwise rotation of the ramus and mandibular relapse. No significant differences in postoperative skeletal and dental stability between groups were observed except for maxillary posterior vertical position. CONCLUSIONS: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure independent of the type of fixation used to stabilize the mandible.     

Stability of skeletal Class III malocclusion after combined maxillary and mandibular procedures: titanium versus resorbable plates and screws for maxillary fixation.

PURPOSE: The aim of this study was to evaluate skeletal stability after double jaw surgery for correction of skeletal Class III malocclusion to assess if there were any differences between resorbable plate and screws and titanium rigid fixation of the maxilla. PATIENTS AND METHODS: Twenty-two Class III patients had bilateral sagittal split osteotomy for mandibular setback stabilized with rigid internal fixation. Low level Le Fort I osteotomy for maxillary advancement was stabilized with conventional titanium plate and screws in 12 patients (group 1) and with resorbable plate and screws in 10 patients (group 2). Lateral cephalograms were taken before surgery, immediately postoperatively, 8 weeks after surgery, and 1 year postoperatively. RESULTS: Before surgery both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary stability was excellent in both groups. In group 1 no significant correlations were found between maxillary advancement and relapse. In group 2, significant correlations were found between maxillary advancement and relapse at A point and posterior nasal spine. No significant differences in postoperative skeletal and dental stability between groups were observed. CONCLUSION: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure for maxillary advancements up to 5 mm independently from the type of fixation used to stabilize the maxilla. Resorbable devices should be used with caution for bony movements of greater magnitude until their usefulness is evaluated in studies with large maxillary advancements.     

Maintenance of soft tissue changes after rigid versus wire fixation for mandibular advancement, with and without genioplasty

OBJECTIVE: This multisite prospective randomized clinical trial examined 2-year longitudinal soft tissue profile changes after bilateral sagittal split osteotomy for mandibular advancement by using rigid or wire fixation, with and without genioplasty. STUDY DESIGN: The study sample consisted of 127 subjects. The rigid-fixation group (n = 78) received 2-mm bicortical position screws, whereas the wire-fixation group (n = 49) received inferior border wires. In the rigid-fixation group, 35 subjects underwent genioplasty, whereas 24 subjects underwent genioplasty in the wire-fixation group. Soft tissue profile changes of labrale inferius, B-point, and pogonion were obtained from digitized cephalometric films taken immediately before surgery and up to 2 years after surgery. RESULTS: Regardless of fixation technique, subjects who had genioplasty in conjunction with the mandibular advancement had the largest surgical movement and the largest postsurgical change (P <.05). When all variables were constant, fixation technique was associated with maintenance of soft tissue change. Subjects who underwent rigid fixation maintained more soft tissue change than patients who underwent wire fixation. CONCLUSIONS: These findings suggest that subjects undergoing rigid fixation and genioplasty maintained the most soft tissue advancement.     

Mandibular,sagittal split osteotomies fixed with biodegradable or titanium screws: a prospective,comparative study of postoperative stability

OBJECTIVE: Comparison of skeletal stability following bilateral sagittal split osteotomy (BSSO) advancement of the mandible fixed with titanium or biodegradable bicortical screws. STUDY DESIGN: Forty consecutive patients underwent mandibular advancement by means of BSSO performed with a standardized technique. In 20 patients rigid fixation was achieved by means of titanium bicortical screws; the other 20 patients were fixed with biodegradable copolymer screws made of poly-L-lactic acid (82%) and polyglycolic acid (18%). Lateral cephalograms were obtained 1 week preoperatively, 1 week postoperatively and after a minimum of 6 months postoperatively. Relevant skeletal points were traced and digitized to evaluate 2-dimensional skeletal change. Changes at each time point were analyzed and compared statistically. RESULTS: There was no statistically significant difference in long-term stability between the 2 groups. No clinical or radiographic evidence of wound healing problems were noted. CONCLUSION: Resorbable poly-L-lactic/polyglycolic acid copolymer bicortical screw fixation of a BSSO is a viable alternative to titanium screws for the fixation of advancement BSSO.     

One-stage approach to the correction of facial skeletal deformity with malocclusion

A total of 40 patients with varying degrees of facial skeletal deformity and Class III malocclusion were treated by bimaxillary osteotomy combining maxillo-malar augmentation and/or osseous genioplasty at the same sitting by the author. In all patients, the maxillary advancement and mandibular set back were performed, using Le Fort I maxillary osteotomy and bilateral sagittal split osteotomy of the mandibular rami. In additional bimaxillary osteotomy, simultaneous maxillo-malar augmentation and genioplasty in 20 patients, genioplasty in 12 patients, maxillo-malar augmentation in eight patients, were performed to improve facial harmony. All patients were followed clinically and radiographically for at least 1 year and as much as 5 years after undergoing surgical correction. No cases with relapse or other major complications have been encountered up to now. There were, however, persisting unilateral inferior alveolar nerve damage in two patients, prolonged nerve anesthesia or hypoesthesia in four patients, and short period anesthesia or hypoesthesia in 11 patients, wide alar base in three patients and slight deviation of cartilage septum in two patients. There were no other complications encountered and an unexpected result. The facial skeletal deformity and malocclusion were always treated satisfactorily as patient and plastic surgeon's expectations in one-stage operation, without significant complications and morbidity.     

In vitro comparison of biomechanical characteristics of sagittal split osteotomy fixation techniques

The aim of the present study was to compare the biomechanical stability of 10 different fixation methods used in sagittal split osteotomy. Twenty-five fresh sheep mandibles were stripped of all soft tissues and sectioned at the midline. A sagittal split osteotomy with 5mm advancement was performed on each hemimandible. The hemimandibles were randomly divided into 10 groups of 5, and then fixed with 5 different bicortical screws, 4 different miniplates with or without bicortical screws, and 1 resorbable screw configuration. All specimens were mounted on a specially designed 3-point biomechanical test model and compression loads were applied using the Lloyd LRX testing machine until 3mm displacement was reached. Load/displacement data were gathered and compared using the Mann-Whitney U-test with Bonferroni correction (P<0.01). The 3 bicortical screws in an inverted backward-L pattern provided the most biomechanical stability of the screw patterns tested. The miniplate fixed obliquely with 2 bicortical screws in the proximal segment provided the most biomechanical stability of the miniplate groups.     

The medial surface of the mandible as an alternative source of bone grafts in orthognathic surgery

A technique of harvesting bone grafts from the medial surface of the angle of the mandible during a bilateral sagittal split osteotomy procedure is described. In 20 patients who underwent mandibular setback for the correction of class III dentofacial deformities, bone grafts were harvested from the medial mandibular angle and used for simultaneous augmentation of the midface or for interpositioning and stabilization of the maxilla after LeFort I maxillary anterior or inferior repositioning. The mean postoperative follow-up was 6 months (range, 3-12 months). No complications occurred, and postoperative morbidity was similar to that encountered by patients who undergo sagittal split osteotomy without bone harvest. The technique described shows that the medial mandibular angle is a suitable donor site for membranous bone grafts in patients who undergo sagittal split osteotomy.