Clinical and magnetic resonance findings in the temporomandibular joints of patients before and after orthognathic surgery

Prevalence of Temporomandibular Disorders in Orthognathic Surgery patients: A systematic review conducted according to PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions

BACKGROUND

Orthognathic surgery is done to treat a variety of dentofacial abnormalities, but a wide gap still remains on how it can result in temporomandibular joint dysfunction (TMD). The primary goal of this review was to assess the effects of various orthognathic surgical techniques on the emergence or exacerbation of TMJ dysfunction.

METHODS

A comprehensive search was conducted across several databases using Boolean operators and MeSH keywords related to temporomandibular joint disorders (TMDs) and orthognathic surgical interventions, with no limitation on the year of publication. Two independent reviewers screened the identified studies based on predetermined inclusion and exclusion criteria, followed by a risk of bias assessment using a standardised tool.

RESULTS

Five articles were considered for inclusion in this review. A greater number of females opted for surgical options than their male cohorts. Three studies were of prospective design, 1 of retrospective and 1 of observational type. Mobility on lateral excursion, tenderness on palpation, arthralgia and popping sounds were the TMD characteristics that showed significant differences. Overall, orthognathic surgical intervention did not show an increase in TMD signs and symptoms as compared to nonsurgical counterparts.

CONCLUSION

Though orthognathic surgery reported greater cases of some TMD symptoms and signs as compared to the nonsurgical cohorts in four studies, the conclusive evidence is debatable. Further studies are recommended with a longer follow-up period and greater sample size to determine the impact of orthognathic surgery on TMJ.

Changes in condylar position after orthognathic surgery and its correlation with temporomandibular symptoms (TMD)- a prospective study

The aim of the study was to assess the changes in the condylar position after orthognathic surgery (OGS) and its effect on temporomandibular disorders (TMD). A total of 37 dentofacial deformity patients included in the study who had undergone OGS were divided into three groups: Group I, Le Fort I maxillary advancement; Group II, bilateral sagittal split osteotomy (BSSO) mandibular advancement ± Le Fort I; and Group III, BSSO mandibular setback ± Le Fort I. Patients were evaluated clinically using Diagnostic Criteria for TMD and by radiography preoperatively and 6 months postoperatively. The positional changes in condyle were correlated with signs and symptoms of TMD. A total of 37 patients in three groups (Group I, 8 patients; Group II, 10 patients; and Group III, 19 patients) were evaluated. Overall, condyles had anterio-medio-inferior movement with 7 of 8 patients in Group I, 6 of 10 patients in Group II and 13 of 19 patients in Group III having ≤2 mm displacement. In angular changes, inward-anterio-medial movement was observed with 6 of 8 patients in Group I; about 5 of 10 patients, and 10 of 19 patients in Group II and III respectively had ≤5° change. Intragroup and intergroup comparisons showed insignificant changes in TMD and linear/angular movement (p ≥ 0.05). Pearson correlation coefficient was found to be nonsignificant on the radiographic and clinical comparison (p ≥ 0.05). Intrarater reliability (Kappa value) was found to be 0.83, confirming the results. Within the limitations of the study it seems that there are minimal linear and angular changes in condyle after orthognathic surgery that were not responsible for the development of temporomandibular disorders in the postoperative course.

The Clinical and Radiographic Changes of Temporomandibular Joint (TMJ) Following Mandibular Set Back Surgery by Bilateral Sagittal Split Osteotomy (BSSO)

Background

Bilateral Sagittal Split Osteotomy (BSSO) is one of the treatment options for Class III maxillary deficiency which may affect the condylar position and the patient’s occlusion. We aimed to evaluate the clinical and radiographic changes of temporomandibular joint (TMJ) following mandibular set back surgery by BSSO.

Methods

In this retrospective study, All Class III patients, aged between 18-30 years old who underwent bimaxillary orthognathic surgery in the Oral and Maxillofacial Surgery Ward of Ghaem Hospital, Mashhad, Iran from January 2018- January 2020 were enrolled. Radiographic changes of joint space, condylar position and clinical changes for maximal mouth opening and joint sound were examined before and 6 months after surgery. Data were analyzed by SPSS16 software and the significance level of the data was set at P-value < 0.05.

Results

Twenty-five patients were recruited. The axial angle of the left and right condyle and condylar inclination on both sides reduced but this reduction was not statistically significant. While the anterior joint space was reduced and posterior joint space was increased in both sides, the changes on the right side were only significant (P = 0.039). In clinical examinations maximum mouth opening, lateral and protrusive movements were also decreased but this reduction was not statistically significant.

Conclusion

The mandibular set back with BSSO surgery in class III skeletal patients had no significant effect on the position of the condyle in the glenoid fossa as well as clinical symptoms.

Effect of computer-assisted design and manufacturing cutting and drilling guides accompanied with pre-bent titanium plates on the correction of skeletal class II malocclusion: a randomized controlled trial

This study was performed to assess the effect of correcting skeletal class II malocclusion based on the application of computer-assisted design and manufacturing (CAD/CAM) cutting and drilling guides accompanied with pre-bent titanium plates. Fifty patients with skeletal class II malocclusion were recruited into this prospective randomized controlled clinical trial and assigned to two groups. Patients underwent bilateral sagittal split ramus osteotomy directed by CAD/CAM cutting and drilling guides accompanied with pre-bent titanium plates (group A) or CAD/CAM splints (group B). Postoperative assessments were performed. Differences between the virtually simulated and postoperative models were measured. Patients in both groups had a satisfactory occlusion and appearance. More accurate repositioning of the proximal segment was found in group A than in group B when comparing linear and angular differences to reference planes; however, no significant difference was revealed for the distal segment. In conclusion, CAD/CAM cutting and drilling guides with pre-bent titanium plates can provide considerable surgical accuracy for the positional control of the proximal segments in bilateral sagittal split ramus osteotomy for the correction of skeletal class II deformities.

Changes in the temporomandibular joint clicking and pain disorders after orthognathic surgery: Comparison of orthodontics-first approach and surgery-first approach

The purposes of this study were to investigate the influence of the orthodontics-first approach (OFA) and surgery-first approach (SFA) on changes in the signs and symptoms of temporomandibular joint disorders (TMDs) and to compare pre- and postoperative orthodontic treatment duration and total treatment duration between the two approaches. This retrospective study recruited 182 adult patients with malocclusions treated with OFA and SFA and recorded variables such as age, gender, skeletal classification, and signs and symptoms of TMD (clicking and pain disorders) before the start of the surgical-orthodontic treatment and after surgery. Changes in the signs and symptoms of TMD and treatment duration were evaluated within each approach and compared between two approaches. A binary logistic regression was performed to assess the influence of the variables on the postoperative signs and symptoms of TMD. There were no significant postoperative changes in temporomandibular joint (TMJ) pain for OFA and SFA, whereas a significant reduction was found in TMJ clicking after surgery for both approaches. According to binary logistic regression, the type of surgical-orthodontic treatment (OFA or SFA) was not a significant risk factor for postoperative TMJ clicking and pain, and the risk of postoperative TMJ clicking and pain was significant only when TMJ clicking (OR = 10.774, p < 0.001) and pain (OR = 26.876, p = 0.008) existed before the start of the entire treatment, respectively. With regard to the treatment duration, SFA (21.1 ± 10.3 months) exhibited significantly shorter total treatment duration than OFA (34.4 ± 11.9 months) (p < 0.001). The results of this study suggest that surgical-orthodontic treatment using SFA can be a feasible option of treatment for dentofacial deformities based on the equivalent effect on TMD and shorter overall treatment period compared to conventional surgical-orthodontic treatment using OFA.

Changes in the temporomandibular joint position depending on the sagittal osteotomy technique and extent of mandibular movement

The bilateral sagittal split osteotomy (BSSO) and high oblique sagittal split osteotomy (HSSO) are common techniques for mandibular movement in orthognathic surgery. The aim of this study was to evaluate the influence of both techniques, as well as movement distances and directions, on the position of the temporomandibular joint (TMJ). A total of 80 mandibular movements were performed on 20 fresh human cadaver heads, four on each head. Pre- and postoperative cone beam computed tomography was used to plan the surgical procedure and analyse the TMJ. Reference measurements included the anterior, superior, and posterior joint spaces, intercondylar distances and angles in the axial and coronal planes, and the sagittal, coronal, and axial angulations of the proximal segment. Only minor differences were found between the BSSO and HSSO techniques, particularly in terms of the intercondylar angle in the axial plane (P <  0.03) and the condylar angle of the proximal segment in the sagittal plane (P <  0.011). Observed changes in the TMJ were mostly opposite when moving the mandible forwards and backwards and increased with increasing movement distance. BSSO and HSSO result in similar changes in TMJ position. The extent of the movement distance influences the position of the condyle more than the osteotomy technique.

MRI Changes in the Temporomandibular Joint after Mandibular Advancement

PURPOSE

Esthetic dental and skeletal component correction can affect the temporomandibular joint (TMJ). Arthrogenic TMJ dysfunction can be present in the joint at the outset or it can develop during the treatment or later. The aim of the present study was to examine the changes found on magnetic resonance imaging (MRI) studies of the TMJ in patients with skeletal Class II malocclusion who had undergone combined orthodontic and bilateral sagittal split ramus osteotomy (BSSRO) advancement. Our objective was to measure the changes in the disc position, condylar translation, secondary bony changes, and joint effusion on MRI before and after treatment.

MATERIALS AND METHODS

An analytical, single-surgeon, single-institution, retrospective radiological (MRI) study was designed. We included patients who had undergone combined orthodontic and BSSRO advancement from 2011 to 2018. All 36 patients were examined using a 1.5-Tesla MRI unit (Siemens Symphony, Erlangen, Germany) with a 6 × 8-cm diameter surface coil, which allowed for simultaneous imaging of both TMJs.

RESULTS

Analysis using the Wilcoxon signed rank test revealed statistically significant differences in the pre- and post-treatment groups in the changes in the position of the disc from anterior disc displacement with reduction (ADDWR) to the normal position (P = .008), condylar translation from excessive to normal (P = .046), and an increase in secondary bony changes (P = .005).

CONCLUSIONS

Combined orthodontic and orthognathic movement in the treatment of skeletal Class II malocclusion can increase secondary bony changes, improve the disc position in ADDWR cases, and control excessive translation of the TMJ. No improvement was noted in the position of the disc in those with anterior disc displacement without reduction, hypomobility and joint effusion.

Evaluation of orthognathic surgery on articular disc position and temporomandibular joint symptoms in skeletal class II patients: A Magnetic Resonance Imaging study

BACKGROUND

The purpose of orthognathic surgery is to correct facial deformity and dental malocclusion and to obtain normal orofacial function. However, there are controversies of whether orthognathic surgery might have any negative influence on temporomandibular (TM) joint. The purpose of this study was to evaluate the influence of orthognathic surgery on articular disc position and temporomandibular joint symptoms of skeletal CI II patients by means of magnetic resonance imaging.

MATERIAL AND METHODS

For this purpose, fifteen patients with skeletal CI II malocclusion, aged 19-32 years (mean 23 years), 10 women and 5 men, from the Isfahan Department of Oral and Maxillofacial Surgery were studied. All received LeFort I and bilateral sagittal split osteotomy (BSSO) osteotomies and all patients received pre- and post-surgical orthodontic treatment. Magnetic resonance imaging was performed 1 day preoperatively and 3 month postoperatively. Descriptive statistics and Wilcoxon and Mc-Nemar tests were used for statistical analysis. P<0.05 was considered significant.

RESULTS

Disc position ranged between 4.25 and 8.09 prior to surgery (mean=5.74±1.21). After surgery disc position range was 4.36 to 7.40 (mean=5.65±1.06). Statistical analysis proved that although TM disc tended to move anteriorly after BSSO surgery, this difference was not statistically significant (p value<0.05).

CONCLUSIONS

The findings of the present study revealed that orthognathic surgery does not alter the disc and condyle relationship. Therefore, it has minimal effects on intact and functional TM joint. Key words:Orthognathic surgery, skeletal class 2, magnetic resonance imaging, temporomandibular disc.

Do patients with malocclusion have a higher prevalence of temporomandibular disorders than controls both before and after orthognathic surgery? A systematic review and meta-analysis

PURPOSE

The aim of this study was to identify, through meta-analysis, whether patients who require orthognathic surgery have a higher prevalence of temporomandibular disorders (TMDs) than controls, both before treatment and after.

MATERIAL AND METHODS

A systematic review and meta-analysis were conducted based on PRISMA guidelines, to address the study purposes. A search of major databases through PubMed, EMBASE, and Cochrane CENTRAL was performed to locate all pertinent articles published from inception to June 2016. Inclusion criteria were controlled clinical studies, either prospective or retrospective, and case-control studies comparing preoperative and postoperative signs and symptoms of TMDs in patients who undergo orthognathic surgery to those of a healthy volunteer population with no dentofacial deformities. The predictor variables were patients with dentofacial deformities who underwent orthognathic surgery and patients with no dentofacial deformities and with good maxillomandibular relations and normal occlusion. The outcomes variables were the weighted, prevalence rate (proportion) in signs and symptoms of TMDs in patients with dentofacial deformities and risk ratio (RR) of signs and symptoms of TMDs before and after orthognathic surgery, compared to the control group.

RESULTS

A total of 542 patients enrolled in 6 studies were included in this analysis. The overall pooled weighted rate or prevalence of TMDs for orthognathic surgery patients preoperatively was 32.5% (95% CI = 26.7%-38.9%). There was a significant difference between the 2 groups with respect to TMDs before surgery, but no significant difference in TMDs after surgery. The RR for patients who had dentofacial deformities before orthognathic surgery compared with a control group was 1.634 (95% CI = 1.216-2.194; P = 0.001). The RR for patients after orthognathic surgery compared with a control group was 1.262 (0.718; 95% CI = 0.805-1.979; P = 0.311).

CONCLUSION

The results of this study show that patients who are going to have a correction of their malocclusion by orthodontics and orthognathic surgery have a significant incidence of TMDs when compared to a control population, but that after treatment, the incidence of TMDs does not differ from a control population. The reasons for these findings are not clear.

TMJ response to mandibular advancement surgery: an overview of risk factors

Objective

In order to understand the conflicting information on temporomandibular joint (TMJ) pathophysiologic responses after mandibular advancement surgery, an overview of the literature was proposed with a focus on certain risk factors.

Methods

A literature search was carried out in the Cochrane, PubMed, Scopus and Web of Science databases in the period from January 1980 through March 2013. Various combinations of keywords related to TMJ changes [disc displacement, arthralgia, condylar resorption (CR)] and aspects of surgical intervention (fixation technique, amount of advancement) were used. A hand search of these papers was also carried out to identify additional articles.

Results

A total of 148 articles were considered for this overview and, although methodological troubles were common, this review identified relevant findings which the practitioner can take into consideration during treatment planning: 1- Surgery was unable to influence TMJ with preexisting displaced disc and crepitus; 2- Clicking and arthralgia were not predictable after surgery, although there was greater likelihood of improvement rather than deterioration; 3- The amount of mandibular advancement and counterclockwise rotation, and the rigidity of the fixation technique seemed to influence TMJ position and health; 4- The risk of CR increased, especially in identified high-risk cases.

Conclusions

Young adult females with mandibular retrognathism and increased mandibular plane angle are susceptible to painful TMJ, and are subject to less improvement after surgery and prone to CR. Furthermore, thorough evidenced-based studies are required to understand the response of the TMJ after mandibular advancement surgery.

Factors of importance for the functional outcome in orthognathic surgery patients: a prospective study of 118 patients

PURPOSE

The aim of this study was to assess the influence of orthognathic surgery on patients' stomatognathic function and, further, to evaluate how post-treatment function relates to satisfaction.

PATIENTS AND METHODS

A total of 118 adult patients (51 men and 67 women) who were treated with orthognathic surgery were examined before and a minimum of 12 months after the surgical intervention. The stomatognathic function was evaluated with Helkimo's Anamnestic and Clinical Dysfunction index. The former was also used to assess a control group of 47 individuals with the same age and gender distribution and with no history of or present need for orthodontic treatment.

RESULTS

A total of 76 patients (64.4%) reported severe dysfunction at the beginning of the treatment, and 24 patients (20.3%) reported severe dysfunction at the end of the treatment. Clinical assessment showed that 36 patients (30.5%) had severe dysfunction symptoms upon inclusion versus only 5 (4.2%) at the final examination. However, 3 patients (2.5%) without clinical dysfunction at the time of inclusion developed mild dysfunction during treatment, and 8 patients (6.8%) developed increased dysfunction during treatment. The patients' functional status after treatment and their degree of satisfaction with the treatment were positively correlated. Although a general improvement was verified, the functional status of those who were treated never reached that of the control group.

CONCLUSION

This study indicates that orthognathic surgery improves patients' stomatognathic function in most cases, and that patients' satisfaction correlated with perceived, reported, and measured function at the end of the treatment.

In vitro biomechanical evaluation of the use of conventional and locking miniplate/screw systems for sagittal split ramus osteotomy

PURPOSE

The aim of this in vitro study was to assess the biomechanical stability of 9 different osteosynthesis methods after sagittal split ramus osteotomy by simulating the masticatory forces and using a 3-point biomechanical test method.

MATERIALS AND METHODS

Forty-five polyurethane hemimandibles with bone-like consistency were randomly assigned to 9 groups (n = 5) and subjected to sagittal split ramus osteotomy. After 4-mm advancement of the distal segment, the bone segments were fixed by different osteosynthesis methods using 2.0-mm miniplate/screw systems: group A, one 4-hole conventional straight miniplate; group B, one 4-hole locking straight miniplate; group C, one 4-hole conventional miniplate and one bicortical screw; group D, one 4-hole locking miniplate and 1 bicortical screw; group E, one 6-hole conventional straight miniplate; group F, one 6-hole locking straight miniplate; group G: two 4-hole conventional straight miniplates; group H, two 4-hole locking straight miniplates; and group I, 3 bicortical screws in an inverted-L pattern. All models were mounted on a base especially constructed for this purpose. Using a 3-point biomechanical test model, the hemimandibles were loaded in compressive strength in an Instron machine (Norwood, MA) until a 3-mm displacement occurred between segments vertically or horizontally. Data were analyzed by analysis of variance and Tukey test (alpha = 1%).

RESULTS

The multiparametric comparison of the groups showed a statistically significant difference (P < .01) between groups that used 2 miniplates (groups G and H), 1 miniplate and 1 bicortical screw (groups C and D), and only bicortical screws (group I) compared with groups that used only 1 miniplate with 2 screws per segment (groups A and B) and 3 screws per segment (groups E and F).

CONCLUSION

The placement of 2.0-mm-diameter bicortical screws in the retromolar region, associated or not with conventional and locking miniplates with monocortical screws, promoted a better stabilization of bone segments. Locking miniplates presented a better performance in bone fixation in all groups.

Orthognathic treatment and temporomandibular disorders: a systematic review. Part 1. A new quality-assessment technique and analysis of study characteristics and classifications

INTRODUCTION

Orthognathic treatment is undertaken to correct jaw discrepancies and involves a combination of orthodontics and surgery. The effects of orthodontic treatment on temporomandibular disorders (TMD) have been widely debated in the literature, but fewer studies focus on the effects of orthognathic treatment on TMD.

METHODS

A systematic review was conducted to (1) determine the percentage of orthognathic patients with signs or symptoms of TMD, (2) establish the range of signs or symptoms, and (3) examine studies that followed patients longitudinally through treatment to determine the effect of orthognathic intervention on TMD symptoms.

RESULTS

Of 480 identified articles, 53 were eligible for inclusion in this review. Part 1 of this 2-part article describes the methodology of conducting this review, the difficulties encountered (including the quality-assessment issues), and a narrative analysis of study characteristics and classification methods. Part 2 reports the remaining results, evidence tables, and meta-analyses.

CONCLUSIONS

The diversity of diagnostic criteria and classification methods used in the included studies makes interstudy comparisons difficult. There is a definitive need for well-designed studies with standardized diagnostic criteria and classification methods for TMD.

Orthognathic treatment and temporomandibular disorders: a systematic review. Part 2. Signs and symptoms and meta-analyses

INTRODUCTION

There have been conflicting viewpoints in the literature regarding the effects of orthognathic treatment on temporomandibular disorders (TMD). A systematic review was conducted to determine the percentage of orthognathic patients with TMD, establish the range of signs and symptoms, and follow patients longitudinally through treatment for any changes in signs and symptoms.

METHODS

Part 1 of this 2-part article described the methodology of this review, with a narrative analysis of the study characteristics and the TMD classification methods. Part 2 describes the percentage of patients suffering from TMD and the signs and symptoms reported. Meta-analyses were conducted on data from clinically similar studies.

RESULTS

Pain decreased after surgery for both self-reported symptoms and clinically diagnosed pain on palpation. However, postsurgical results were more varied for joint sounds. The percentage of patients with clicking had a tendency to decrease postsurgery, but improvements in crepitus were questionable. The results from all meta-analyses in this review were subject to considerable statistical heterogeneity, and it was not possible to draw strong inferences relating to the percentage of orthognathic surgery patients with TMD with any degree of certainty.

CONCLUSIONS

Although orthognathic surgery should not be advocated solely for treating TMD, patients having orthognathic treatment for correction of their dentofacial deformities and who are also suffering from TMD appear more likely to see improvement in their signs and symptoms than deterioration.

Occlusal Risk Factors for Temporomandibular Disorders

OBJECTIVE

To determine the role of occlusal variables (overbite; overjet; number of anterior and posterior teeth; bilateral canine guidance on lateral and protrusive movements; anterior centric slide; Angle Classes I, II, and III malocclusion) as risk indicators for the development of temporomandibular disorders (TMDs).

MATERIALS AND METHODS

Seventy-two TMD patients with myofascial pain, with or without limited opening and arthralgia, as well as 30 age- and gender-matched pain-free concurrent controls were included. The association (critical odds ratio [OR] = 2.0) between the significant occlusal variables and TMD was calculated. Confounders were controlled in the inclusion-exclusion criteria as well as in the analysis stage (unconditional logistic regression) by variation in the OR (15%).

RESULTS

Angle Class II malocclusion (crude OR = 8.0, confidence interval [CI] = 2.2 to 29.3) and the absence of bilateral canine guidance on lateral excursion (crude OR = 3.9, CI = 1.6 to 9.7) were statistically more common in patients than in controls. Spontaneous pain as well as pain on palpation (Class II or higher) were also statistically worse in TMD patients. Significant confounders (ie, employment, age, cigarette and alcohol consumption) acted as effect modifiers not changing the critical OR (adjusted OR Angle Class II and bilateral canine guidance = 8.3 to 12.4 and 2.2 to 4.1, respectively).

CONCLUSIONS

Absence of bilateral canine guidance on lateral excursion and particularly Angle Class II malocclusion were considered important risk indicators for the development of TMD in this investigation, even when some sociodemographic factors were considered as effect modifiers.

Masticatory function and neurosensory disturbance after mandibular correction by bilateral sagittal split ramus osteotomy: a comparison between miniplate and bicortical screw rigid internal fixation

Bilateral sagittal split osteotomy is commonly used to treat mandibular prognathism. Several fixation methods for bony segments have been described. The present study compared masticatory function and neurosensory recovery patterns after mandibular correction between two methods of rigid fixation, bicortical screw (n = 38) and monocortical miniplate (n = 32). Patients who had undergone bilateral sagittal split osteotomy for Class III malocclusion were reviewed, and masticatory function and neurosensory recovery were studied with the appropriate indicators at 1, 3, 6 and 12 months postoperatively. Minimal differences were seen between groups at 1-year postoperatively, and although patients treated with miniplate fixation tended to recover faster, with regard to masticatory function and neurosensory disturbance, than those treated with screw fixation, no significant differences were identified. As the two methods seem to provide equal comfort and reliability, the choice should be made by the individual surgeon.

MRI characteristics of anterior disc displacement with and without reduction

OBJECTIVES

The aim of this study was to investigate the differences between magnetic resonance imaging (MRI) characteristics of anterior disc displacement with reduction (ADDR) and without reduction (ADDWR).

METHODS

A clinician and a radiologist, blinded to the results of the clinical examination, independently evaluated the MRI scans of 100 subjects with symptoms of temporomandibular joint (TMJ) disorders. The final sample included 88 subjects in whom there was consensus of disc displacement both between observers and between MRI and clinical examination. There were 130 joints with ADDR and 45 joints with ADDWR in the study. The MRI characteristics such as position, signal intensity and morphology of the disc, degenerative changes, effusion, scar tissue, osteonecrosis and condylar hypermobility were evaluated in the cases of ADDR and ADDWR. The chi(2) test was used to determine the differences between ADDR and ADDWR for these MRI characteristics.

RESULTS

There were no significant differences between ADDR and ADDWR for effusion and degenerative changes. There were significant differences between ADDR and ADDWR for sideways displacement, disc deformation, signal intensity changes, scar tissue, osteonecrosis and condylar hypermobility.

CONCLUSIONS

Degenerative changes and effusion did not appear to be markers of either ADDR or ADDWR. However, the severity of these abnormalities may be correlated with the type of internal derangement. The prevalence of sideways displacement, disc deformation, signal intensity changes, scar tissue, and osteonecrosis was greater in ADDWR than ADDR. These conditions may be considered to be indicators of more advanced and complicated stages of internal derangement. Because the percentage of subluxation was greater in ADDR, localized joint laxity and internal derangement may be correlated.

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.

Stabilisation of sagittal split advancement osteotomies with miniplates: a prospective, multicentre study with two-year follow-up. Part II. Radiographic parameters

This prospective study implied a two-year follow-up on a group of patients that underwent a Bilateral Sagittal Split Osteotomy (BSSO) for advancement (n=222) of the mandible that were treated in seven institutions following the same treatment protocol. The aim of Part II of this study was to correlate the clinical findings on stability and relapse as reported in Part I (clinical parameters) of this series of articles with the cephalometric findings. The mean skeletal relapse at pogonion of the whole group after two years was 0.9 mm. The clinically stable group, however, had only 0.4 mm relapse, whereas the clinical relapse group showed a mean relapse of 3.3 mm. The findings underline a relationship between the amount of advancement and relapse. The tendency for both, horizontal and vertical movement is the same, i.e., the larger the surgery effect, the larger the relapse. The angle post plane/mandibular plane showed the highest explained variance 9%. Patients with a high mandibular plane angle may be more prone to relapse. The explained variance of all considered prognostic factors together, however, is small (13%). The findings of this study express that patients with a clinical stable occlusion after a BSSO advancement, stabilised with miniplates, have a minimal to no skeletal relapse as measured on the cephalometric radiograms. The clinically non-stable group, however, appeared to have considerable skeletal relapse.

High-resolution 3-D shape integration of dentition and face measured by new laser scanner

Face and dentition were measured using a high-resolution three-dimensional laser scanner to circumvent problems of radiation exposure and metal-streak artifacts associated with X-ray computed tomography. The resulting range data were integrated in order to visualize the dentition relative to the face. The acquisition interval for dentition by laser scanner was 0.18 mm, and complicated morphologies of the occlusal surface could be sufficiently reproduced. Reproduction of occlusal condition of upper and lower dentitions was conducted by matching the surface of the occlusal impression record with upper dentition data. To integrate dentition and face, a marker plate interface was devised and adopted on the lower dental cast or by the subject directly. Integration was performed by matching both sets of interface data. Reproduction of the occlusal condition and integration of the dentition and face were accomplished and visualized satisfactorily by computer graphics. The integration accuracy was examined by changing the attachment angle of the marker plate, and the marker plate attached at 45 degrees showed the smallest error of 0.2 mm. The current noninvasive method is applicable to clinical examination, diagnosis and explanation to the patient when dealing with the physical relationship between face and dentition.

Condylar and temporomandibular joint disc positions after mandibular osteotomy for prognathism

PURPOSE

The purpose of this study was to compare the changes in temporomandibular joint (TMJ) morphology and clinical symptoms after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) with and without a Le Fort I osteotomy.

PATIENTS AND METHODS

Of 43 patients with a diagnosed jaw deformity, 20 underwent IVRO without internal fixation and 23 underwent SSRO with rigid internal fixation. Some operations were performed in combination with a Le Fort I osteotomy. The TMJ symptoms and joint morphology, including the disc position, were assessed preoperatively and postoperatively using magnetic resonance imaging (MRI) and axial cephalography.

RESULTS

A significant difference in the direction of condylar rotation was seen in horizontal axial cephalography images (P <.01). Fewer or no TMJ symptoms were reported postoperatively by 88% of the patients who underwent IVRO with or without a Le Fort I osteotomy and by 66.7% of patients who underwent SSRO with or without a Le Fort I osteotomy. In sagittal images, no change was seen in anterior disc displacement after SSRO; however, improvement was seen in 44.4% of patients with anterior disc displacement who underwent IVRO with or without a Le Fort I osteotomy.

CONCLUSION

These results suggest that SSRO does not improve anterior disc displacement; IVRO improves anterior disc displacement in the initial postsurgical period, and both procedures may improve TMJ symptoms.