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

Systematic mapping review of orthognathic surgery

STUDY DESIGN

Systematic mapping review AIM AND SCOPE: The objective of this mapping review was to identify, describe, and organize clinical research currently available from systematic reviews and primary studies regarding co-interventions and different surgical modalities used in orthognathic surgery (OS) and their outcomes.

METHODS

Systematic reviews (SRs), randomized controlled trials, and observational studies that evaluated perioperative OS co-interventions and surgical modalities were identified in an exhaustive search of MEDLINE, EMBASE, Epistemonikos, Lilacs, Web of Science, and CENTRAL. Grey literature was also screened.

RESULTS

Included were 35 SRs and 253 primary studies, 103 from SRs, and another 150 identified in our search. Overall, SR quality was rated as critically low, with only two SRs rated as of high quality. 19 questions on population, interventions, comparisons, and outcomes (PICO) extracted from the SRs focused on osteosynthesis methods, surgical cutting devices, and use of antibiotics, corticosteroids, and induced hypotension. Also identified were 15 research gaps. Evidence bubble maps were created to graphically depict the available evidence.

CONCLUSION

Future high-quality research, both primary and secondary, is needed to address the knowledge gaps identified in this systematic mapping review.

Efficacy and morbidity of biodegradable versus titanium osteosyntheses in orthognathic surgery: A systematic review with meta-analysis and trial sequential analysis

Titanium osteosynthesis is currently the gold standard in orthognathic surgery. Use of biodegradable osteosyntheses avoids removal of plates/screws in a second operation. This systematic review aimed to assess the efficacy and morbidity of biodegradable vs. titanium osteosyntheses in orthognathic surgery (PROSPERO CRD42018086477). Patients with syndromic disorder(s) and/or cleft lip/palate were excluded. Randomised, prospective and retrospective controlled studies were searched for in nine databases (February 2021). The time periods perioperative, short‐term, intermediate, long‐term, and overall follow‐up were studied. Meta‐analyses were performed using random‐effects models. A total of 9073 records was assessed, of which 33 were included, comprising 2551 patients. Seven RCTs had ‘some concerns’ while another seven RCTs had ‘high’ risk of bias (Cochrane‐RoB2). No differences in malunion (qualitative analyses), mobility of bone segments [RR 1.37 (0.47; 3.99)], and malocclusion [RR 0.93 (0.39; 2.26)] were found. The operative time was longer in the biodegradable group [SMD 0.50 (0.09; 0.91)]. Symptomatic plate/screw removal was comparable among both groups [RR 1.29 (0.68; 2.44)]. Skeletal stability was similar in most types of surgery. Biodegradable osteosyntheses is a valid alternative to titanium osteosyntheses for orthognathic surgery, but with longer operation times. Since the quality of evidence varied from very low to moderate, high‐quality research is necessary to elucidate the potential of biodegradable osteosyntheses.

Long-term stability of isolated advancement genioplasty, and influence of associated risk factors: A systematic review

The aim of this review was to investigate the skeletal and soft tissue stability of isolated advancement genioplasty after more than 1 year, and to observe the influence of associated risk factors. A literature search was performed on PubMed, Web of Science, Embase, ScienceDirect, and Cochrane. Only studies with at least 10 patients who underwent an isolated advancement genioplasty, and with a follow-up period of at least 1 year, were included. Of the 2224 records initially identified, eight articles met the eligibility criteria. The mean age of the total study population was 23 years and ranged from 19.1 to 26.5 years in the individual studies. The average surgical advancement at pogonion was 8.2 mm and ranged from 6.2 to 11.7 mm in the individual studies. After 1 year, the horizontal hard tissue relapse at the level of pogonion varied from 0.1 to 2.1 mm. In two studies, this was reported as statistically significant. Regarding the soft tissue, the horizontal relapse varied from 0.3 to 2.9 mm, which was also considered statistically significant in two studies. Isolated advancement genioplasty was found to be a predictable and stable orthognathic procedure in the sagittal plane at both soft and hard tissue levels. The amount of relapse was not associated with the fixation method or with the amount of surgical advancement.

[Alveoloplasty and the use of osteosynthesis material in the cleft lip palate]

OBJECTIVES

To compare the results of secondary alveoloplasty performed in one Hospital when osteosynthesis material was used and when the bone graft does not require this material, and relating them to factors such as gender and age.

MATERIAL AND METHODS

A retrospective study was conducted from the years 2014 to 2019 in this Hospital on the selected patients who met the inclusion criteria. Two periods of ages, period A: ages between 5-12 years (mixed secondary alveoloplasty) and period B: greater than 12 years (late secondary alveoloplasty). Autologous bone from the iliac crest or parietal calotte was used for the bone graft. The patients were divided into 2 groups: group I: patients with alveoloplasties that required osteosynthesis material. Group II: patients who did not require osteosynthesis material. Parameters evaluated: the success criteria for alveoloplasty were assessed according to the clinical parameters described by Precious. Alveoloplasty was successful if they met all the criteria of Precious in the year of intervention. Postoperative complications in both groups were evaluated. The statistical analysis was performed using the exact Fisher test for qualitative variables.

RESULTS

Alveoloplasty was successful in 89.4% of patients in group I, while it was 90.3% in group II. Alveoloplasty was successful in 87.5% of females compared to 91.17% of males. The intervention was a success in 91.48% of patients in group A, compared to 66.6% in group B. The osteosynthesis material in two patients of group I was not degraded in the annual assessment. There were no significant differences in any of the comparisons.

CONCLUSIONS

The use of osteosynthesis material does not alter the integration of the bone graft in patients that undergo alveoloplasty. Factors such as gender or age do not influence the results of the interventions.

Resorbable versus titanium plates for orthognathic surgery

BACKGROUND

Recognition of some of the limitations of titanium plates and screws used for the fixation of bones has led to the development of plates manufactured from bioresorbable materials. Whilst resorbable plates appear to offer clinical advantages over metal plates in orthognathic surgery, concerns remain about the stability of fixation and the length of time required for their degradation and the possibility of foreign body reactions. This review compares the use of titanium versus bioresorbable plates in orthognathic surgery and is an update of the Cochrane Review first published in 2007.

OBJECTIVES

To compare the effects of bioresorbable fixation systems with titanium systems used during orthognathic surgery.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 20 January 2017); the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 11) in the Cochrane Library (searched 20 January 2017); MEDLINE Ovid (1946 to 20 January 2017); and Embase Ovid (1980 to 20 January 2017). We searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (clinicaltrials.gov; searched 20 January 2017), and the World Health Organization International Clinical Trials Registry Platform (searched 20 January 2017) for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Randomised controlled trials comparing bioresorbable versus titanium fixation systems used for orthognathic surgery in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias of the included studies. We resolved disagreement by discussion. Clinical heterogeneity between the included trials precluded pooling of data, and only a descriptive summary is presented.

MAIN RESULTS

This review included two trials, involving 103 participants, one comparing titanium with resorbable plates and screws and the other titanium with resorbable screws. Both studies were at high risk of bias and provided very limited data for the primary outcomes of this review. All participants in one trial suffered mild to moderate postoperative discomfort with no statistically significant difference between the two plating groups at different follow-up times. Mean scores of patient satisfaction were 7.43 to 8.63 (range 0 to 10) with no statistically significant difference between the two groups throughout follow-up. Adverse effects reported in one study were two plate exposures in each group occurring between the third and ninth months. Plate exposures occurred mainly in the posterior maxillary region, except for one titanium plate exposure in the mandibular premolar region. Known causes of infection were associated with loosened screws and wound dehiscence with no statistically significant difference in the infection rate between titanium (3/196), and resorbable (3/165) plates.

AUTHORS' CONCLUSIONS

We do not have sufficient evidence to determine if titanium plates or resorbable plates are superior for fixation of bones after orthognathic surgery. This review provides insufficient evidence to show any difference in postoperative pain and discomfort, level of patient satisfaction, plate exposure or infection for plate and screw fixation using either titanium or resorbable materials.

Efficacy and Safety of Biodegradable Osteofixation Devices in Oral and Maxillofacial Surgery: a Systematic Review

The use of osteofixation devices should be evidence-based if uncomplicated bone healing is to be achieved. Numerous studies describe and claim the advantages of biodegradable over titanium devices as a bone fixation method. Here, we systematically review the available literature to determine the clinical efficacy and safety of biodegradable devices compared with titanium devices in oral and maxillofacial surgery. In addition, related general aspects of bone surgery are discussed. We conducted a highly sensitive search in the databases of MEDLINE (1966–2005), EMBASE (1989–2005), and CENTRAL (1800–2005) to identify eligible studies. Eligible studies were independently evaluated by two assessors using a quality assessment scale. The study selection procedure revealed four methodologically ‘acceptable’ articles. Owing to the different outcome measures used in the studies, it was impossible to perform a meta-analysis. Therefore, the major effects regarding the stability and morbidity of fracture fixation using titanium and biodegradable fixation systems were qualitatively described. Any firm conclusions regarding the fixation of traumatically fractured bone segments cannot be drawn, due to the lack of controlled clinical trials. Regarding the fixation of bone segments in orthognathic surgery, only a few controlled clinical studies are available. There does not appear to be a significant short-term difference between titanium and biodegradable fixation systems regarding stability and morbidity. However, definite conclusions, especially with respect to the long-term performance of biodegradable fixation devices used in maxillofacial surgery, cannot be drawn. Abbreviations: CENTRAL, Cochrane Central Register of Controlled Trials; MeSH, Medical Subject Heading; VAS, Visual Analogue Scale; and W, weight.

Biodegradable and Titanium Osteosynthesis Provide Similar Stability for Orthognathic Surgery

PURPOSE

The purpose of this study was to test the hypothesis that there is no difference in skeletal stability and material-related complications for titanium or biodegradable fixation when used for various orthognathic surgeries.

MATERIALS AND METHODS

A systematic and electronic search of several databases with specific keywords, a reference search, and a manual search through September 2014 was performed. The inclusion criteria were clinical human studies, including randomized controlled trials, controlled clinical trials, and retrospective studies, with the aim of comparing titanium and biodegradable osteosynthesis after various orthognathic surgeries. The outcome variables of horizontal and vertical relapse using cephalometrics and material usability were statistically analyzed.

RESULTS

The initial PubMed search identified 557 studies, 22 of which met the inclusion criteria (8 randomized controlled trials, 10 controlled clinical trials, and 4 retrospective studies). No statistical difference was found between the 2 groups regarding skeletal stability after various orthognathic surgeries. There was no statistical difference with regard to wound problems, plate and screw removal, and palpability between biodegradable and titanium osteosynthesis, but there was a statistical difference with regard to intraoperative fracture of plates and screws in the biodegradable group.

CONCLUSION

The results of this meta-analysis support the hypothesis that biodegradable fixation devices offer similar skeletal stability as titanium fixation for orthognathic surgery. The results of this study also show that titanium fixation produced fewer broken screws during surgery compared with biodegradable screws.

Comparison of the long-term skeletal stability between a biodegradable and a titanium fixation system following BSSO advancement - a cohort study based on a multicenter randomised controlled trial

Biodegradable fixation systems could reduce or eliminate the problems associated with removal of titanium plates. A multicenter randomised controlled trial (RCT) was performed in the Netherlands from December 2006-July 2009, and originally 230 injured and orthognathic patients were included. The patients were randomly assigned to either a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The aim of the present study was to compare the long-term skeletal stability of advancement bilateral sagittal split osteotomies (BSSO) of a biodegradable system and a titanium system. Only patients from the original RCT who were at least 18 years old and who had a BSSO advancement osteotomy were included. Those who had simultaneous Le Fort I osteotomy or genioplasty were excluded. Analysis of skeletal stability was made by digital tracing of lateral cephalograms. Long-term skeletal stability in BSSO advancement did not differ significantly between patients treated with biodegradable plates and screws and those treated with titanium plates and screws. Given the comparable amount of relapse, the general use of Inion CPS in the treatment of BSSO advancement should not be discouraged. On the basis of other properties a total picture of the clinical use can be obtained; the short-term stability, the intraoperative switches, the number of plates removed and cost-effectiveness. Trial registration of original RCT: http://www.controlled-trials.com; ISRCTN 44212338.

Comparison of titanium and biodegradable plates for treating midfacial fractures

PURPOSE

The purpose of the present study was to evaluate the use of titanium plates and screws (TPSs) versus biodegradable plates and screws (BPSs) for fixation of midfacial fractures. In addition, complications related to the plates and rates of secondary surgery for plate removal were compared.

PATIENTS AND METHODS

From March 2005 to March 2012, 109 patients were enrolled in this study. Fifty-six patients with TPSs implanted to fix midfacial fractures (group A) and 53 patients with BPSs to treat midfacial fractures (group B) were evaluated. Patients' histories of plate-related nonunion, infection, displacement, pain, and palpability and secondary surgery for plate removal were checked.

RESULTS

None of the study participants developed nonunion issues related to the TPSs or BPSs. Six patients in group A developed complications associated with TPSs and 5 patients underwent secondary surgery for plate removal. One patient (1.8%) had a plate-related infection, 1 patient (1.8%) developed plate extrusion, 1 patient (1.8%) had plate-associated chronic pain, 2 patients (3.6%) complained of palpability, and 2 patients (3.6%) developed psychological problems (1 patient developed 2 complications). In contrast, only 1 patient in group B (2%) complained of temporary palpability, and this problem disappeared over time. None of the patients in group B complained of any other problems.

CONCLUSIONS

The results indicated that BPSs and TPSs have the potential for successfully treating midfacial fractures. BPSs are suitable for treating midfacial fractures and could serve as an alternative for TPSs in selected cases.

Novel reconstructive methods of the conchal central strut using an absorbable plate after total harvesting of the conchal cartilage

PURPOSE

Conchal cartilage is widely used in the field of plastic surgery, but donor-site morbidity is inevitable when all of the conchal cartilage is harvested. To maintain ear shape, the authors introduce a new method using an absorbable plate to reconstruct the conchal central strut after total harvesting of the conchal cartilage.

METHODS

In total, 18 subjects underwent surgery, and 14 subjects who were followed up for more than 12 months were included in this article. Before the total harvesting of the conchae, an absorbable plate was adjusted to the proper curvature and length. After harvesting, the central strut was reconstructed by the precrafted absorbable plate. When the harvested cartilage was too large or one implant was not sufficient to reconstruct the central strut, an additional implant was added to the cymba conchae.Outcomes were evaluated by photogrammetry and questionnaires. Seven items were selected to evaluate the shape of the ear and conchal cavity. The authors compared preoperative and postoperative photographs, looking at proportion indices of 7 items using Photoshop. Ten assessors who did not participate in the operation were also shown preoperative and postoperative photographs and answered questionnaires about the shapes of the ear, conchal cavity, and conchal central strut.

RESULTS

Except for the effective conchal cavity height index, no statistically significant differences were observed between preoperative and postoperative ear shapes. Additionally, the questionnaire showed excellent assessments for all items.

CONCLUSIONS

Reconstruction of the central strut using an absorbable plate after total harvest of the conchal cartilage was a simple and effective method to prevent ear collapse.

Effect of number and geometry of resorbable screws on biomechanical stability of in vitro model with sagittal split ramus osteotomy

The purpose of this study was to investigate the effect of the number and the geometry of resorbable screws (RSs; Inion CPS System; Inion Ltd, Tampere, Finland) on the biomechanical stability of the in vitro model with sagittal split ramus osteotomy. The sagittal split ramus osteotomy polyurethane hemimandible (Synbone, Malans, Switzerland) was fixed by 7 osteosynthesis methods after 5 mm advancement of the distal segment (n = 5 for each method): 1TP (1 titanium miniplate and 4 screws), 3RL (3 RSs with linear configuration at the retromolar area [RMA]), 2R1B (2 RSs at RMA and 1 RS at the mandibular body [MB]), 2R1A (2 RSs at the RMA and 1 RS at the mandibular angle [MA]), 3R1B (3 RSs at RMA and 1 RS at the MB), 3R1A (3 RSs at RMA and 1 RS at the MA), and 3R1A1B (3 RSs at the RMA, 1 RS at the MA, and 1 RS at the MB). Values of linear compressive load were measured at 1- to 5-mm displacement of the lower first molar with a 1-mm interval and were statistically analyzed. From 1- to 5-mm displacement, there were significant differences in load values among groups (P < 0.05, P < 0.01, P < 0.01, P < 0.001, and P < 0.001, respectively). When the amount of displacement was increased, the difference in load values between 1TP, 3RL, and 2R1B became significantly prominent. There was a significant difference in total load values according to number and geometry of RSs (P < 0.001). All kinds of geometry with more than 3 RSs were more rigid than 1TP. The 3R1A1B method showed better biomechanical stability than 1TP, 3RL, and 2R1B. In 3 RS and 4 RS groups, fixation in MA (2R1A, 3R1A) exhibited a tendency of better stability than fixation in MB (2R1B, 3R1B). Fixation with 2R1A could provide better biomechanical stability than 1TP and similar rigidity with 3R1A1B.

A randomized clinical trial of biodegradable and titanium fixation systems in maxillofacial surgery

Biodegradable fixation systems could reduce or delete the problems associated with metallic systems, since removal is not necessary. The aim of this study was to establish the effectiveness and safety of biodegradable plates and screws as potential alternatives to metallic ones. This multi-center randomized controlled trial was conducted from December 2006 to July 2009. Included were patients who underwent mandibular and/or Le Fort I osteotomies and those with fractures of the mandible, maxilla, and zygoma. The patients were assigned to a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The primary outcome measure was 'bone healing 8 weeks post-operatively'. The Intention-To-Treat (ITT) analysis of 113 patients in the titanium group and 117 patients in the biodegradable group yielded a significant difference (p < 0.001), primarily because in 25 patients (21%) who were randomized to the biodegradable group, the surgeon made the decision to switch to titanium intra-operatively. Despite this 'inferior' primary outcome result, biodegradable plates and screws could be safely used when it was possible to apply them. The benefits of using biodegradable systems (fewer plate removal operations) should be confirmed during a follow-up of minimally 5 years (Controlled-trials.com ISRCTN number 44212338).

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

INTRODUCTION

Resorbable 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 METHODS

This 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.

RESULTS

The 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.

CONCLUSIONS

The 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.

Stability of maxillary position after Le Fort I osteotomy using self-reinforced biodegradable poly-70L/30DL-lactide miniplates and screws

PURPOSE

The purpose of this study was to evaluate the stability of Le Fort I osteotomy using self-reinforced biodegradable poly-70L/30DL-lactide miniplates and screws.

PATIENTS AND METHODS

Nineteen patients who had Le Fort I osteotomy and internal fixation using self-reinforced biodegradable poly-70L/30DL-lactide miniplates and screws were evaluated both radiographically and clinically. Changes in maxillary position after operation were documented 1 week, 1, 3, 6 mo, and/or 1-yr postoperatively with lateral cephalometric tracings. Complications of the self-reinforced biodegradable poly-70L/30DL-lactide miniplates and screws were evaluated by follow-up roentgenograms and clinical observation. A mixed model analysis for repeated measures was used for statistical analysis.

RESULTS

Maxillary position was stable after operation with no change between time points (P > .05). There were no complications with the self-reinforced biodegradable poly-70L/30DL-lactide miniplates and screws.

CONCLUSIONS

Internal fixation of the maxilla after Le Fort I osteotomy with self-reinforced biodegradable poly-70L/30DL-lactide miniplates and screws is a reliable method for maintaining the postoperative maxillary position after Le Fort I osteotomy.

Comparison of titanium and biodegradable miniplates for fixation of mandibular fractures

PURPOSE

The purpose of the present study was to compare the use of biodegradable miniplates and titanium miniplates for the fixation of mandibular fractures.

PATIENTS AND METHODS

BioSorb FX biodegradable plates and screws and titanium miniplates were used in 91 patients (65 males and 26 females; age range 11 to 69 years) for the treatment of mandibular fractures. The clinical and radiographic findings were recorded at 1, 3, 6, and 12 months after surgery.

RESULTS

The overall complication rate was 4.41%. In the biodegradable plate group, infection occurred in 2 cases (4.26%) and was resolved by incision and drainage and antibiotics. In the titanium plate group, infection occurred in 1 case and plate fracture in 1 case (4.56%). The fractured plate was removed, and a new titanium miniplate was applied using a trocar. The infection was resolved with antibiotics. No adverse tissue reactions, malocclusions, or malunions occurred during the observation period.

CONCLUSIONS

Our results have shown that the rate of morbidity is very low with the use of biodegradable plates and titanium plates, suggesting that biodegradable and titanium plates have the potential for successful use in the fixation of mandibular fractures.

Use of resorbable implants for mandibular fixation: a systematic review

Titanium plating is recognized as the criterion standard for the treatment of mandibular fractures and osteotomies. Use of resorbable implants is well documented in the literature for a range of craniofacial fractures. However, no clear review exists of the use of resorbable implants on the mandible. In this systematic review, we searched MEDLINE/PubMed and the Cochrane Database for studies of resorbable mandibular fixation. Two independent reviewers analyzed the search results using specific inclusion/exclusion criteria. Twenty-two articles detailing 19 studies, including 1 randomized controlled trial were analyzed in this study. These studies included fixation of mandibular fractures at various locations or fixation of bilateral sagittal split osteotomies. Overall, we found a total of 326 patients treated with resorbable plates and screws and 112 patients treated with resorbable screws alone. Analysis of these studies indicates that several material types are used in resorbable mandibular implants, including poly-L-lactic acid (PLLA) and 70% poly-L-lactic acid/30% poly-D,L-lactic acid (PLLA 70/PDLLA 30), coming from at least 10 different manufacturers. Mean follow-up ranged from 3 to 348 weeks. Based on the reported data, we found a total of 14 to 15 infections, 2 foreign body reactions, 7 malocclusions, 8 malunions, and 8 to 10 premature removals in the plate group and 1 foreign body reaction and 2 malocclusions in the screws-only group. These results should be interpreted in the context of the patient selection criteria in the studies. This systematic review demonstrates the need for further randomized controlled trials in this area and concludes with such a study design.

Comparison of titanium and resorbable copolymer fixation after Le Fort I maxillary impaction

INTRODUCTION

Advances in skeletal stabilization techniques have led to the use of titanium devices for rigid fixation. Their advantages include strength and skeletal stability, but they also have disadvantages. The purpose of this study was to investigate the stability of a resorbable copolymer as a potential alternative to titanium for fixation of Le Fort I maxillary impaction.

METHODS

Fifty consecutive patients underwent maxillary impaction with nonsegmental monopiece Le Fort I osteotomy. Twenty-five patients were treated with titanium fixation; 25 patients were treated with resorbable copolymer fixation (82% poly-L-lactic acid: 18% polyglycolic acid). Lateral cephalograms were obtained 1 week preoperatively, 1 week postoperatively, and a minimum of 8 months postoperatively. Linear and angular measurements were recorded digitally to evaluate 2-dimensional skeletal changes.

RESULTS

Statistical analysis showed no significant radiographic differences (P <0.05) in long-term stability in or between the 2 groups. No clinical or radiographic evidence of wound healing problems was noted.

CONCLUSIONS

These results support the use of resorbable copolymer fixation for Le Fort I impaction as a viable alternative to titanium fixation.

Basic guidelines for the surgical correction of mandibular anteroposterior deficiency and excess

During the past decades, knowledge and understanding of all aspects of orthognathic surgery have increased greatly. Diagnostic skills and treatment planning have become more sophisticated and, through experience, surgical techniques have attained a level enabling the treatment of the most complex jaw deformities with confidence. In this article, guidelines for the treatment of mandibular anteroposterior dentofacial deformities are discussed. It should, however, always be kept in mind that the face and mouth are complex, three-dimensional structures and multifunctional in character. An artistic flair and the ability to think originally have become essential for the orthognathic surgeon, because no two dentofacial deformities are the same.

Bioabsorbable Plate and Screw Fixation in Orthognathic Surgery

This paper describes the author's 10-year experience in using resorbable polymeric plates and screws in select cases of orthognathic surgery as well as a comprehensive review of all published reports on this technology for similar applications.

Resorbable versus titanium plates for orthognathic surgery

BACKGROUND

Recognition of some of the limitations of titanium plates and screws used for the fixation of bones has led to the development of plates manufactured from bioresorbable materials. Whilst resorbable plates appear to offer clinical advantages over metal plates in orthognathic surgery, concerns remain about the stability of fixation and the length of time required for their degradation and the possibility of foreign body reactions.

OBJECTIVES

To compare the effectiveness of bioresorbable fixation systems with titanium systems used during orthognathic surgery.

SEARCH STRATEGY

We searched the following databases: Cochrane Oral Health Group Trials Register (to 26th January 2006); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 4); MEDLINE (without filter) (from 1966 to 26th January 2006); and EMBASE (without filter) (from 1980 to 26th January 2006).

SELECTION CRITERIA

Randomised controlled trials comparing resorbable versus titanium fixation systems used for orthognathic surgery.

DATA COLLECTION AND ANALYSIS

Clinical heterogeneity between the included trials precluded pooling of data, and only a descriptive summary is presented.

MAIN RESULTS

This review included two trials, involving 103 participants, one compared titanium with resorbable plates and screws and the other titanium with resorbable screws, both provided very limited data for the primary outcomes of this review. All patients in one trial suffered mild to moderate postoperative discomfort with no statistically significant difference between the two plating groups at different follow-up times. Mean scores of patient satisfaction were 7.43 to 8.63 (range 0 to 10) with no statistically significant difference between the two groups throughout follow up. Adverse effects reported in one study were two plate exposures in each group occurring between the third and ninth months. Plate exposures occurred mainly in the posterior maxillary region, except for one titanium plate exposure in the mandibular premolar region. Known causes of infection were associated with loosened screws and wound dehiscence with no statistically significant difference in the infection rate between titanium (3/196), and resorbable (3/165) plates P = 0.83 (published as P = 0.67).

AUTHORS' CONCLUSIONS

This review provides some evidence to show that there is no statistically significant difference in postoperative discomfort, level of patient satisfaction, plate exposure or infection for plate and screw fixation using either titanium or resorbable materials in orthognathic surgery.

Stability of craniofacial PLLA/PGA copolymer bioabsorbable screws

The behavior of bioabsorbable plates and screws after implantation is a dynamic process that results in dimensional changes of the devices after surgery. Bioabsorbable plates frequently are recognized as changing because of their size, but bioabsorbable screws are less appreciated in this regard. How bioabsorbable screws may change after placement and whether their manufacturing method has an influence on size and shape after implantation needs further study. Using 1.5-mm diameter screws made of an oriented copolymer of 82% poly-L-lactic acid and 18% polyglycolic acid (LactoSorb copolymer), screw dimensions were measured before and after soaking in an in vitro pH 7.4, 37 degrees C buffer environment. After 33 days of exposure to buffer, there were no changes in the physical appearance of the screws, and there was no change in dimensions or shape. The orientation of polymer materials in a bioabsorbable screw device improves its strength and can retard the rate of hydrolysis. However, the residual stresses in oriented screws theoretically can potentiate dimensional shift in the implants during hydrolysis. That such shift did not occur during the early phase of hydrolysis provides further evidence of the mechanism by which these types of screws can maintain biomechanical function throughout the bone-healing phase of the craniofacial skeleton.

One-year postoperative stability of LeFort I osteotomies with biodegradable fixation: A retrospective analysis of skeletal relapse

INTRODUCTION

The purpose of this retrospective analysis was to determine the magnitude of postoperative skeletal relapse of a maxillary LeFort I osteotomy procedure performed with fixation plates and screws composed of a biodegradable copolymer (poly-L lactic and poly-L glycolic acid).

METHODS

Twenty-three consecutively treated subjects, aged 19 to 39, were diagnosed with excess vertical maxillary height or anteroposterior maxillary deficiency and treated with LeFort I impaction or advancement osteotomies. Lateral cephalometric radiographs were measured and compared for the absolute magnitude of skeletal relapse from pretreatment to immediately postoperative to 1 year after surgery.

RESULTS

Correlation analysis determined that a positive relationship existed between the magnitude of the surgical movement and the magnitude of postoperative relapse. The greatest relapse for any subject in any direction was 0.940 mm (anterior nasal spine to nasion-perpendicular). The greatest average relapses were 0.249 mm horizontally (anterior nasal spine to Frankfort horizontal) and 0.141 mm vertically (M-point Frankfort horizontal).

CONCLUSIONS

The most significant contribution of this study to surgical stability literature is reporting the absolute magnitudes of postoperative relapse over a 1-year period of observation. Consistent with previously published reports on postoperative stability, greater magnitudes of relapse were noted for larger surgical movements, yet the absolute values of postoperative relapse with biodegradable copolymers was clinically negligible. Biodegradable copolymers can provide excellent postoperative stability for superior and anterior maxillary surgical repositioning that appears to rival published stability measurements for rigid internal metallic fixation.

Skeletal Stability in Bimaxillary Orthognathic Surgery: P(L/DL)LA-Resorbable versus Titanium Osteofixation

BACKGROUND

One-year skeletal stability following bimaxillary orthognathic surgery was assessed by comparing poly(L-lactide-co-DL-lactide) to titanium osteofixation.

METHODS

Thirty patients underwent osteofixation with poly(L-lactide-co-DL-lactide) copolymer and 30 had 2.0-mm titanium-miniplate osteosyntheses. Lateral cephalograms were analyzed preoperatively, postoperatively, and at 1-year follow-up. Average +/- SD values were as follows in resorbable plate-osteosyntheses (number of cases/titanium controls): for maxillary advancement, 3.5 +/- 4.1 mm (n = 19)/5.4 +/- 3.5 mm (n = 21); setback, 2.8 +/- 3.7 mm (n = 9)/1.9 +/- 1.8 mm (n = 8); elongation, 4.2 +/- 3.6 mm (n = 18)/3.7 +/- 5.2 mm (n = 14); and intrusion, 1.9 +/- 1.7 mm (n = 12)/3.3 +/- 2.7 mm (n = 13); for mandibular advancement, 4.6 +/- 3.6 mm (n = 10)/6.3 +/- 8.8 mm (n = 18); setback, 7.5 +/- 8.3 mm (n = 20)/7.2 +/- 3.2 mm (n = 12); enlargement of the mandibular angle, 11.8 +/- 9.9 degrees (n = 19)/7.9 +/- 6.6 degrees (n = 21); and reduction, 4.5 +/- 3.2 degrees (n = 9)/6.3 +/- 6.6 degrees (n = 9).

RESULTS

Preoperative to postoperative landmark positions within the study and control groups differed highly significantly (p = 0.008, paired t test), yet the amount of operative movement was comparable between the study and control groups (p = 0.5, two-sided t test). Absolute instability at the advanced A-point was (study group/controls) 2.3 +/- 1.8/2.4 +/- 2 mm, setback was 2.3 +/- 1.9 mm/2.5 +/- 1.7 mm, elongation at the anterior nasal spine was 3.8 +/- 3.1 mm/3.1 +/- 3.6 mm, intrusion was 2.1 +/- 1.9 mm/2.2 +/- 1.5 mm, advancement instability at the B-point was 4.9 +/- 4.3 mm/5.1 +/- 8.2 mm, setback was 3.0 +/- 2 mm/1.7 +/- 2 mm, mandibular angle enlargement instability was 6.7 +/- 8.9 degrees/8.2 +/- 9.6 degrees, and angle narrowing was 6.8 +/- 5.2 degrees/4.2 +/- 5.9 degrees. Absolute postoperative instability did not differ significantly between the study and control groups (p = 0.6).

CONCLUSIONS

Resorbable osteofixation as tested proved to be as reliable as titanium, but as the study and control groups were not matched, the results have to be interpreted as preliminary. Resorbable materials permitted clinically faster occlusal and condylar settling than standard titanium osteosyntheses, as bone segments showed slight clinical mobility up to 6 weeks postoperatively.

Self-reinforced biodegradable screw fixation compared with titanium screw fixation in mandibular advancement

PURPOSE

This report compares the skeletal stability and treatment outcomes of 2 similar cohorts undergoing bilateral sagittal osteotomies of the mandible for advancement. The study groups included patients stabilized with 2-mm self-reinforced polylactate (PLLDL 70/30), biodegradable screws (group B), and 2-mm titanium screws placed in a positional fashion (group T).

MATERIALS AND METHODS

Sixty-nine patients underwent bilateral sagittal osteotomies of the mandibular ramus for advancement utilizing an identical technique. There were 34 patients in group B and 35 patients in group T. Each patient had preoperative, immediate postoperative, splint out, and 1-year postoperative cephalometric radiographs available for analysis. The method of analysis and treatment outcomes parameters are identical to those previously used. Repeated measures analysis of variance was performed with means of fixation as the between-subject factor and time as the within subject factor. The level of significance was set at .01.

RESULTS

There were no clinical failures in group T and a single failure in group B. The average difference in stability between the groups is small and subtly different at the mandibular angle. The data documented similarity of the postsurgical changes in the 2 groups with the only statistically significant difference being the vertical position of the gonion (P < .001) and the mandibular plane angle (P < .01) with greater upward remodeling at gonion in group T.

CONCLUSIONS

Two-mm self-reinforced PLLDL (70/30) screws can be used as effectively as 2-mm titanium screws to stabilize the mandible after bilateral sagittal osteotomies for mandibular advancement. The difference in 1-year stability and outcome is minimal.

Immediate mechanical stability of sagittal split ramus osteotomy fixed with resorbable compared with titanium bicortical screws in mandibles of sheep

Ten fresh mandibles from adult sheep were stripped of all soft tissues and sectioned in the midline. We did sagittal split osteotomies and 5 mm advancement on all the 20 hemimandibles. Ten hemimandibles were fixed with three 2.0 mm x 13 mm titanium bicortical screws, and the other 10 were fixed with three 2.0 mm x 13 mm poly-l-lactic acid/polyglycolic acid (PLLA/PGA) bicortical screws in an inverted L pattern. All the hemimandibles were then mounted in a servohydraulic testing unit and tested to permanent deformation. Maximum forces that the mandibles resisted before breaking, maximum displacements, and the displacement values under 20, 60, 120, and 150 N were compared using the Mann-Whitney U-test. There were no significant differences in stability between the bones fixed with titanium and those fixed with resorbable screws.

Cirurgia ortognática: orientações legais aos ortodontistas e cirurgiões bucofaciais

Os autores entrevistaram especialistas em Ortodontia e em Cirurgia Bucomaxilofacial, elaboraram uma lista de ocorrências específicas do dia-a-dia do exercício da especialidade, redigindo, com base na legislação vigente e na literatura, uma série de orientações, atitudes e comportamentos que sugerem como rotina aos profissionais.

In vivo experimental study on bone regeneration in critical bone defects using an injectable biodegradable PLA/PGA copolymer

OBJECTIVES

An assessment was done of the bone-healing rate after implantation of a polylactide/polyglycolide copolymer (PLA-PGA) 50/50 dispersed in aqueous solution of PGA and dextran, used as bone substitutes in an animal model.

STUDY DESIGN

Two groups of 5 rabbits each were used. In both the femoral condyles, a critical size defect of 6x10 mm was made. On the right side PLA/PGA was inserted; the left side remained empty. Thirty and 90 days after surgery the animals were killed.

RESULTS

Defects left unfilled showed no spontaneous healing after 30 and 90 days. Sites filled with experimental materials showed new bone ranging between 11.46% and 76.82% after 30 days, and 75.98% and 95.34% after 90 days. Histomorphometry showed an increase in bone maturation between day 30 and 90 in experimental sites. At day 90, no statistical difference was seen as compared to normal bone.

CONCLUSION

PLA/PGA copolymer dispersed in hydrosoluble matrix seems to be suitable as osteoconductive material in critical size defects.