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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.

Bioabsorbable fixation devices have been used in our departments between November 1991 and November 2001 in orthognathic surgery. The aim of this retrospective study was to assess all complications experienced during this time period, when we have operated 163 patients who have undergone 329 orthognathic osteotomies fixated with bioresorbable devices. No postoperative intermaxillary fixation was used. Light guiding elastics were used for 5 to 7 weeks. Patients' acceptance was generally excellent and very few complications occurred during this follow-up of 10 years. The complications were minor and did not affect the end results of the operations. Minor complications occurred in 14 patients (8.6%). Only one patient (0.6%) had a postoperative infection with elevated infection parameters. The other minor complications consisted mainly of dehiscence of the wound and plate exposure together with granulation tissue in the operation field. The rest of the complications occurred in the beginning of our study, when large screw heads on top of the bone irritated the patient and had to be removed. Insufficient fixation resulted in open bite in three patients (1.8%) in the beginning of the trial use of new devices, which no longer are used. Based on our experience, bioresorbable devices are safe to be used in orthognathic procedures. However, there is a learning curve, as there is with all new methods introduced.

Bioabsorbable fixation devices have been used in craniomaxillofacial (CMF) surgery since the early 70's. In our departments the experimental use started in the 80's with self-reinforced (SR) polylactide devices. The first clinical operations were carried out in 1991. Since that time, we have used different types of self-reinforced bioabsorbable devices in the fixation of several hundreds of osteotomies and fractures. Patients' acceptance has been generally excellent and very few complications occurred during this follow-up of over 10 years. The complications have been minor and have not affected the end results of the operations. In only one oncologic patient, the devices needed to be removed and replaced with a rigid reconstruction plate. The minor complications consisted mainly of a few infections, dehiscence of the wound and plate exposure together with granulation tissue in the operation field. No implant-specific complications were recorded. However, there is a learning curve for the surgeon, as there is with all new methods introduced. Based on our experience, self-reinforced bioabsorbable devices are safe to be used in several indications in the craniomaxillofacial skeleton, also in load-shearing situations.

Four mandibular screw-plate locking systems were studied in sheep. Three to four centimetres angular continuity resections of the mandible were performed and the defects bridged with pre-bent angular reconstruction plates fixed with four screws in the body part and three in the ramus. Each type was used four times. Clinical and radiological examinations were carried out 1 and 2 months later. All sheep were able to eat and ruminate normally throughout the postoperative period. Radiology revealed that 6/16 plates and 5/112 screws fractured during the follow-up period. In one type, no fracture occurred. Screw fracture was confined to just one reconstruction system. Six of 16 mandibles showed slight to moderate bone resorption under the plate. The results point to the internal shortcomings of the systems tested.

Background and Objectives: The use of bioabsorbable materials in craniomaxillofacial surgery began a new era in fracture fixation. The purpose of this paper is to review the historical perspectives and the current concept of bioresorbable materials in fracture fixation., Methods and Materials: The authors review the biochemistry and clinical characteristics of bioabsorbable polymers--polylactic acid (PLA), polyglycolic acid (PGA), polydioxanone (PDS), and their copolymers. Their use and clinical perspectives by the Helsinki (authors') group and other study groups are presented., Results and Conclusions: These materials have proven to be safe in clinical applications. When manufactured with current technology, they are easy to handle. Economically, they are nearly equal to similar metal devices. The materials have met clinical success throughout the world, first in orthognathic surgery, followed by treatment of fractures of the upper facial skeleton and the mandible. Today, most maxillofacial fractures and osteotomies may be adequately fixed with bioabsorbable materials.

Mandibular body osteotomies were fixed in nine sheep using new totally amorphous (70L:30DL), self-reinforced, polylactide (SR-PLA) lag screws and in nine sheep using standard stainless steel lag screws. No intermaxillary fixation was used. During follow-up, radiological, histological and microradiological studies were undertaken at 3, 6, 12 and 24 weeks. In both groups, all osteotomies consolidated at similar rates and no adverse reaction to the screws was seen. However, displacements of the fixed osteotomy fragments were common in both groups during the first 3 weeks. The biocompatibility of SR-PLA during the follow-up period was found to be good. Only initial signs of biodegradation were seen. The results of this study indicate that (70L:30DL) SR-PLA has potential for use as a fixation screw material in oral and maxillofacial surgery, and that further studies using this material are justified.

Purpose: The purpose of this study was to evaluate the utility of biodegradable, self-reinforced poly-L-lactide screws (SR-PLLA) for lag-screw fixation of anterior mandibular fractures., Patients and Methods: SR-PLLA lag-screws were used to stabilize anterior mandibular fractures in 11 patients. Maxillomandibular fixation was used to treat concomitant mandibular condyle fractures for 2 weeks in four patients and for 1 and 5 weeks in two patients. Clinical and radiologic follow-up lasted for 6 months in 36% of patients and for 1 year in 64%., Results: Healing of all anterior fractures was uneventful, with no displacement or delay of bony union. No adverse reactions to the biodegradable screws were seen during follow-up., Conclusion: Biodegradable SR-PLLA screw fixation seems to be a new and promising way of treating anterior mandibular fractures.

In orthognathic surgery, the bone fragments are usually fixed with metallic plates and screws. Metallic devices other than titanium plates are usually removed after the osteotomy has consolidated, which often requires general anaesthesia. Titanium plates, supposed to be biotolerable, have been introduced in order to overcome this need for secondary intervention. However, due to corrosion, titanium particles have been found in scar tissue covering these plates and in locoregional lymph nodes. Therefore, their removal is also advocated. Self-reinforced poly (L-lactide) homopolymer (PLLA) and poly (L/D-lactide) stereocopolymers with a L/D molar ratio up to 85/15 have sufficient strength to overcome the need for additional support for the fixation of fractures. The plates can be bent at room temperature. The surgical technique and early results of a case of bimaxillary surgery and genioplasty fixed with bioresorbable material without postoperative rigid maxillomandibular fixation are reported.

Skeletal stability during the first year after mandibular advancement surgery and fixation using biodegradable self-reinforced poly-l-lactide (SR-PLLA) screws, without postoperative intermaxillary fixation, was studied in 25 patients by means of cephalometric measurements. The magnitude of advancement was on average, 3.88 mm at pogonion (PG) (range 1.25-6.5 mm) and 4.57 mm at B-point (range 2.75-7.5 mm). After one year a mean relapse backwards of 0.59 mm at the PG (15%) and 0.78 mm at the B-point (17%) was observed. Nineteen patients (76%) and 17 patients (68%) were stable at PG and B-point, respectively. SR-PLLA screws are considered to be comparable to other forms of rigid internal fixation for fixation of bilateral splitting osteotomies after mandibular advancement, as far as skeletal stability is concerned.

The objective of the study was to evaluate the use of a totally biodegradable fixation device in the fixation of mandibular osteotomy in sheep. Mandibular unilateral body osteotomies were fixed with biodegradable self-reinforced poly-L-lactide (SR-PLLA) multi-layer plates and screws in nine sheep. The unoperated sides acted as control. The follow-up times were 6, 12 and 24 weeks, after which radiological, mechanical and histological studies were carried out. An analysis of the implanted material was also carried out. The results showed that the SR-PLLA plates and screws were strong enough to fix the osteotomy and that the osteotomies healed mainly with callus formation. Therefore we conclude that SR-PLLA multi-layer plates and screws can be used together successfully in the fixation of mandibular osteotomies without maxillomandibular fixation. However, before they can be used in humans, the size of the plate and screws should be decreased.

Mandibular angular ostectomy defects in 12 sheep were bridged with a titanium plate system (THORP), designed according to the screw-plate-locking principle. Two screw designs (hollow and solid) and two rough (plasma-coated, sand-blasted)-surface and one smooth (anodized)-surface structure were tested in a critical two-screw anchorage model. Fixation with two screws only per fragment was successful in only one-third of the cases. The fixation results were superior for screws with a rough surface, either sand-blasted or plasma-coated. The hollow-screw design did not seem to offer special advantages over the solid screws with identical surface structure. In the successful cases, the bone-screw contact was maintained continuously over a period of 8 weeks, and anchorage was even enhanced by reinforcement of the cancellous structures. In the unsuccessful cases, peri-implant bone resorption seemed to be related to jeopardized bone perfusion in the vicinity of the implants. It is presumed that a plating system with locked screws has the advantage that only two screws will hold a relatively short condylar process. This study proved the assumption to be questionable. However, in view of the problems related to prosthetic replacement of the temporomandibular joint, an attempt to salvage the articular portion may still be justified in selected cases, even if the chance of success is as low as 30%.

Objective: This study was carried out to evaluate clinical and radiologic results after lag-screw fixation (LSF) of mandibular parasymphyseal and angular fractures was performed., Study Design: Seven angle and 17 parasymphyseal fractures in 23 adult patients with mandibular fractures were treated by transoral reduction and LSF. Clinical and radiologic examinations were undertaken during a 3-month follow-up period, Results: All parasymphyseal fractures and four angular fractures went to good bone union after surgery. Infectious complications occurred in two patients with parasymphyseal fractures. These resolved with simple procedures. Three angular fractures needed refixing because of instability. Slight occlusal adjustment was needed in five patients. Postoperative neurosensory deficits were transient in every case in which they were seen., Conclusions: LSF of mandibular parasymphyseal fractures is a practical and effective way of fixing such fractures internally. It leads to good bone healing without permanent neurosensory deficit or increased risk of malocclusion. In mandibular angle fractures LSF is likely to be too technique-sensitive to allow its extensive use.

Purpose: This study evaluates the clinical and radiologic results after open reduction and lag-screw osteosynthesis of fractured mandibular condyles., Materials and Methods: Eleven adult patients underwent surgery for displaced or dislocated mandibular condyle fractures via a submandibular approach. The repositioned fragments were fixed using lag screws designed by Krenkel or Eckelt. Maxillomandibular fixation was used postoperatively for 2.6 weeks on average (range, 1 to 4 weeks) in nine patients., Results: Slight transient weakness of the mandibular branch of the facial nerve occurred in three cases. Occlusal adjustment was needed in another three cases. Radiologically, the fracture line disappeared at 22.5 weeks on average (range, 8 to 38 weeks). Three screws had to be removed because of loosening. There were signs that the screws had migrated caudally from their original position in seven cases. Twenty-one months on average after operation (range, 8 to 31 months), patients were satisfied with treatment. Clinically, all patients had a stable occlusion and symmetry of the face. All had greater than 5-mm symmetrical lateral jaw excursions. Ten patients had wide (> 40 mm) painless mouth opening. Healing in malposition occurred in four cases and there was considerable shortening of the mandibular ramus in four cases., Conclusions: Despite good clinical results, lag screws do not meet the needs for rigid internal fixation in the treatment of mandibular condyle fractures.

Nine patients underwent bilateral sagittal split osteotomies of the mandible. The osteotomies were fixed using two self-reinforced poly-L-lactide screws. No maxillomandibular fixation was used postoperatively. The preliminary results with the shortest follow-up of 15 months show that primary healing was normal. No late-term clinical complications were encountered during the follow-up, the longest of which is now 23 months.

Eighteen oblique osteotomies in sheep mandibular condylar necks were fixed with self-reinforced poly-L-lactide (SR-PLLA) (n = 9) or stainless steel (n = 9) screws (core diameters 2.4, 2.7, 3.0, or 3.5 mm). No intermaxillary fixation (IMF) was applied. The follow-up periods were 6, 12, and 24 weeks, respectively, after which the sheep were killed, and the status of the condylar head was assessed radiographically and histologically. The results showed that the fixation had been adequate. Bony destruction, osteophytes, and flattening of the condylar head, however, were frequently observed in both groups, as compared with the unoperated contralateral condyle. Histologic studies revealed that the thickness of the condylar head cartilage had increased and that the boundaries of the different cell layers were irregular, as was the junction of cartilage and bone. The diameter of the screw did not seem to have any influence on the occurrence of either radiologic or histologic signs of condylar degeneration. These findings indicate that screw fixation of condylar fractures in the mandible without IMF might result in degenerative joint disease.

To evaluate the benefits of narrow-beam roentgenography and spiral tomography for examination and monitoring of screw and plate fixation to bone we studied 22 rigid plate bridgings of mandibular defects. The plate reconstructions were of long duration or considered permanent. In 13 patients, AO-THORP (AO: Arbeitsgemeinschaft für Osteosynthesefragen; THORP: Titanplasma-beschichteten Hohl- und Vollkern-Rekonstruktionsplatten-Systems) reconstructions were used and in nine classic AO stainless steel plate bridgings. With the AO-THORP system, good bone apposition to the screws was evident in 96% (73/76 screws) of the cases. Fixation using the classic AO screws, however, was inadequate in 30% (20/66 screws) of the cases. Plate loosening was noted in 56% (5/9 plates). Examination using narrow-beam roentgenography and spiral tomography provided detailed information about bone resorption around the screws and provided a reliable tool for deciding on a follow-up regimen. When complications occur, they can be detected and treated early, reducing patient morbidity. In our opinion, classic AO plate bridging should always be considered temporary.

A new application of the titanium hollow screw reconstruction plate (THORP) system, originally designed for bridging mandibular defects, is presented. Because of the screw-plate locking principle, the system allows rigid fixation of the plate without unphysiologic load to the bone underneath. A case is presented with a large squamous cell carcinoma requiring bilateral total maxillectomy. The titanium plate was attached horizontally to the zygomatic bones with two titanium hollow screws on each side. Six months later a prosthetic device was constructed and attached to the exposed part of the plate by a modified bar and clips system. The patient is able to speak, chew, and swallow without difficulty.

Self-reinforced poly-L-lactide (SR-PLLA) screws were used to fix bilateral mandibular sagittal split osteotomies (SSO) in six sheep. No intermaxillary fixation was used postoperatively. The follow-up time was 16 weeks, after which the sheep were killed. Both sides of the mandible were photographed and radiographed. The bending strength of the osteotomy was measured on the left side of the mandible. Histological and microradiographic studies were performed on the right side of the mandible. The results showed that the SR-PLLA screws were strong enough to fix the SSO rigidly. The bending force needed to break the bone was greater than that for the average unoperated mandible. The histological and microradiographic studies showed uneventful healing of the osteotomies in all six sheep. The results indicate that this method should be suitable for rigid fixation of SSO and fractures of the mandible in human beings.

To compare two different mandibular reconstruction systems, a 5-cm angular resection was performed in nine adult sheep. The defect was reconstructed using either a classic AO plate or the AO-THORP reconstruction system. The animals were killed 5, 9, and 14 weeks after operation. Serial sections with the plates and screws in place were prepared and studied histologically and with microradiography and fluorescence microscopy. Twenty-six percent of the 2.7-mm AO cortical screws were adequately fixed. The corresponding percentage for AO-THORP hollow screws was 73%. The main advantage of the latter system is the screw-plate locking principle, which allows plate stability to be maintained even if bone is resorbed under the plate. Whether the existence of a screw lumen is an advantage has not yet been established.