Long-term outcomes after treatment of condylar fracture by intraoral access: a functional and radiologic assessment.

PURPOSE: The aim of the present study was to investigate radiographic and functional long-term results after condylar fractures have been reduced by an exclusively intraoral surgical approach. PATIENTS AND METHODS: A total of 25 (21 male, 4 female) consecutive patients with 30 condylar process fractures were retrospectively investigated. Clinical follow-up was performed in 19 patients (16 male, 3 female) with a total of 24 fractures. Median postoperative follow-up time was 19.7 months. Surgical indications followed specific parameters of fracture localization, dislocation, and ramus shortening. All patients were examined in accordance with the Research Diagnostic Criteria for Temporomandibular Dysfunction (RDC/TMD) and the Helkimo Index. Orthopantomograms (OPGs) were analyzed with use of the condylar morphologic scale (CMS), and mandibular ramus position and height were measured. RESULTS: Fractures were classified as condylar neck (n = 2) and basis fractures (n = 28), according to criteria of the Strasbourg Osteosynthesis Research Group (SORG). Mean age of patients was 33 years (standard deviation [SD], 13 yr). RDC/TMD measurements at follow-up showed a mean mouth opening of 48 mm (SD, 9), mandibular laterotrusion right of 11 mm (SD, 3.8), laterotrusion left of 10 mm (SD, 4.5), and protrusion with a mean of 5.83 mm (SD, 3). No joint clicking, weakness of the facial nerve, or joint or muscular pain was observed. Statistical analysis of the CMS showed significantly better postoperative ramus height (P < .05). CONCLUSION: Reduction achieved by this technique allows reconstruction of anatomic ramus height in combination with excellent functional results.     

Bad split during bilateral sagittal split osteotomy of the mandible with separators: a retrospective study of 427 patients

An unfavourable fracture, known as a bad split, is a common operative complication in bilateral sagittal split osteotomy (BSSO). The reported incidence ranges from 0.5 to 5.5%/site. Since 1994 we have used sagittal splitters and separators instead of chisels for BSSO in our clinic in an attempt to prevent postoperative hypoaesthesia. Theoretically an increased percentage of bad splits could be expected with this technique. In this retrospective study we aimed to find out the incidence of bad splits associated with BSSO done with splitters and separators. We also assessed the risk factors for bad splits. The study group comprised 427 consecutive patients among whom the incidence of bad splits was 2.0%/site, which is well within the reported range. The only predictive factor for a bad split was the removal of third molars at the same time as BSSO. There was no significant association between bad splits and age, sex, class of occlusion, or the experience of the surgeon. We think that doing a BSSO with splitters and separators instead of chisels does not increase the risk of a bad split, and is therefore safe with predictable results.     

A novel instrument for the prevention of condylar torque in bilateral sagittal ramus osteotomy when using bicortical screw fixation

When using the bilateral sagittal split osteotomy (BSSO) technique, rigid internal fixation (RIF) remains the standard method to accurately fix the distal and proximal osteotomy fragments. A concern with the use of RIF, especially with bicortical screws, is the increased risk of condylar torque and its functional consequences. This technical note introduces a new method for preventing torque of the mandibular condyles after BSSO, using a sagittal split space maintainer.     

Intraoperative removal of third molars does not affect the postoperative infections after BSSO - Randomized controlled trial

The goal of this study was to evaluate the incidence of postoperative wound infection and timing of mandibular third molar removal in bilateral sagittal split osteotomy (BSSO).This wis a prospective, single-blinded, randomized, split-mouth clinical trial. All patients were divided into two groups: Group I, where pre-operative removal of the third molars were done 6 months prior to BSSO and Group II, where intra-operative removal of contralateral third molars were done for the same patients during the osteotomy. The primary outcome variable studied was postoperative infection rate and the secondary outcome variable was bad split during BSSO.Among the seventy five patients (150 sites), one site in group II developed infection whereas none of the sites in group I developed infection (p = 1.000). No sites had bad split in both the groups.The results from the present study show that there is no difference between the presence or absence of mandibular third molars on post-operative wound infection following bilateral sagittal split osteotomy, and the authors hence suggest removing third molars during BSSO for patient comfort.     

Clinical and radiographic evaluation of a computer-generated guiding device in bilateral sagittal split osteotomies

The bilateral sagittal split osteotomy (BSSO) is one of the main orthognathic surgery procedures used for managing skeletal mandibular excess, deficiency or asymmetry. It is known to be a technique-sensitive procedure with high reported incidences of inferior alveolar nerve injury, bad splits and post-surgical relapse. With the increasing use of computer-assisted techniques in orthognathic surgery, the accurate transfer of the virtual plan to the operating room is currently a subject of research. This study evaluated the efficacy of computer-generated device at maintaining the planned condylar position and minimizing inferior alveolar nerve injury during BSSO. The device was used in 6 patients who required isolated mandibular surgery for correction of their skeletal deformities. Clinical evaluation showed good recovery of the maximal incisal opening and a reproducible occlusion in 5 of the 6 patients. Radiographic evaluation showed better control of the condyle position in both the vertical and anteroposterior directions than in the mediolateral direction. The degree of accuracy between the planned and achieved screw positions were judged as good to excellent in all cases. Within the limitations of this study and the small sample size, the proposed device design allowed for good transfer of the virtual surgical plan to the operating room.     

Presence of mandibular third molars during bilateral sagittal split osteotomy increases the possibility of bad split but not the risk of other post-operative complications

Timing of third molar removal in relation to bilateral sagittal split osteotomy (BSSO) is controversial, especially with regard to post-operative complications. We investigated the influence of mandibular third molar presence on complications after BSSO with sagittal splitters and separators, by a retrospective record review of 251 patients (502 surgical sites). Mandibular third molars were present during surgery at 169 sites and removed at least 6 months preoperatively in 333 sites. Bad splits occurred at 3.0 % (5/169) and 1.5% (5/333) of the respective sites. Presence of mandibular third molars significantly increased the risk of bad splits (OR 1.08, CI 1.02–1.13, p < 0.01). The mean incidences of permanent neurosensory disturbances, post-operative infection, and symptomatic removal of the osteosynthesis material were 5.4% (OR, 0.89; 95% CI, 0.79–1.00; p = 0.06), 8.2% (OR, 1.09; 95% CI, 0.99–1.20; p = 0.63), and 3.4% (OR, 0.97; 95% CI, .92–1.03; p = 0.35) per site, respectively, without a significant influence of mandibular third molar status. In conclusion, the presence of mandibular third molars during surgery increases the possibility of bad split but does not affect the risk of other complications. Therefore, third molars can be removed concomitantly with BSSO using sagittal splitters and separators.     

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.     

Static and dynamic loading of mandibular condyles and their positional changes after bilateral sagittal split advancement osteotomies

This study analysed the effects of change of direction of masseter (MAS) and medial pterygoid muscles (MPM) and changes of moment arms of MAS, MPM and bite force on static and dynamic loading of the condyles after surgical mandibular advancement. Rotations of the condyles were assessed on axial MRIs. 16 adult patients with mandibular hypoplasia were studied. The mandibular plane angle (MPA) was <39° in Group I (n=8) and >39° in Group II (n=8). All mandibles were advanced with a bilateral sagittal split osteotomy (BSSO). In Group II, BSSO was combined with Le Fort I osteotomy. Pre and postoperative moment arms of MAS, MPM and bite force were used in a two-dimensional model to assess static loading of the condyles. Pre and postoperative data on muscle cross-sectional area, volume and direction were introduced in three-dimensional dynamic models of the masticatory system to assess the loading of the condyles during opening and closing. Postsurgically, small increases of static condylar loading were calculated. Dynamic loading decreased slightly. Minor rotations of the condyles were observed. The results do not support the idea that increased postoperative condylar loading is a serious cause for condylar resorption or relapse.     

The Unfavourable Split: a novel classification and an 11-year retrospective study looking at alternative methods for management of this well-known complication

An unfavourable split is a well-known complication following a sagittal split osteotomy (SSO) of the mandible. Our aim was to analyse all unfavourable mandibular splits that had occurred when carrying out a SSO with the aim to design a classification which can facilitate management. We carried out a retrospective study analysing all orthognathic surgery from January 2010 until April 2021. Data surrounding unfavourable splits during this period were specifically analysed. Orthognathic surgery during this period was performed by a single OMFS unit with osteotomies performed by a single surgeon and their trainee. The dataset included 311 patients who underwent either a bilateral sagittal split osteotomy (BSSO) or a bimaxillary osteotomy. There were 225 bimaxillary osteotomies and 86 BSSOs. Twenty-one patients had unfavourable splits following their BSSO with a total of 22 out of 622 sagittal split osteotomies over this 11-year period. Bilateral unfavourable splits occurred in one patient. These results correlate to an incidence rate of 6.8% of unfavourable splits following SSO's in an 11-year period. The results reveal common patterns of unfavourable splits to suggest a simple classification based on our results. This can be applied to any unfavourable splits in SSO which then allows the clinician to proceed with surgery and prevent abandonment of the procedure. It is classified as follows: Type 1 fractures where the mandibular condyle is attached to the proximal fragment; Type 2 fractures whereby the mandibular condyle is attached to the tooth-bearing segment; Type 3 fractures are lingual cortex fractures. Each of these fracture types has a specific management protocol, which we recommend is used in all unfavourable splits.     

Neurosensory disturbances one year after bilateral sagittal split osteotomy of the mandibula performed with separators: A multi-centre prospective study

Bilateral sagittal split osteotomy (BSSO) is an effective and commonly used treatment to correct mandibular hypo- and hyperplasia. Hypoesthesia of the inferior alveolar nerve (IAN) is a common complication of this surgical procedure. This prospective multi-centre study aimed to determine the incidence of neurosensory disturbances of the IAN after BSSO procedures performed without the use of chisels. Our study group comprised 158 patients, with a follow-up period of 1 year, who underwent BSSO (with or without Le Fort I) that incorporated the use of sagittal split separators and splitters but no chisels. The percentage of BSSO split procedures that resulted in IAN damage was 5.1%. The percentage of patients (without genioplasty) who experienced IAN damage was 8.9%. The concomitant genioplasty in combination with BSSO was significantly associated with hypoesthesia. Peri-operative removal of the wisdom tooth or a Le Fort I procedure did not influence post-operative hypoesthesia. We believe that the use of splitting forceps and elevators without chisels leads to a lower incidence of persistent post-operative hypoesthesia 1 year after BSSO of the mandible, without increasing the risk of a bad split.     

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.     

Open Reduction and Rigid Internal Fixation of Mandibular Condylar Fractures by an Intraoral Approach: A Long-Term Follow-Up Study of 15 Patients

PURPOSE: To evaluate the long-term results obtained with open reduction and rigid internal fixation of mandibular condylar fractures by an intraoral approach. PATIENTS AND METHODS: Fifteen patients with 24 mandibular condylar fractures were retrospectively examined with an average follow-up of 23 months (range, 6-63 months). Clinical and radiographic examination was conducted according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), including an evaluation of maximum voluntary bite force measurements and facial nerve function. Statistical analysis was performed on maximum voluntary bite force measurements and maximum pressure pain threshold. RESULTS: Two patients fulfilled the criteria for a RDC/TMD diagnosis. Myofacial pain (group I) and bilateral arthralgia (group III), combined with a moderate nonspecific physical symptom score, was diagnosed in 1 patient and 1 patient received a diagnosis of disc displacement with reduction (group II). Satisfying radiographic fracture healing was seen in 12 joints. However, miniplate fracture occurred in 3 patients and severe bone resorption of the condylar head was seen in one patient. Minor adjustment of the postoperative occlusion was necessary in 6 patients. No significant difference between maximum voluntary isometric bite force measurements or maximum pressure pain threshold was found between the fracture side and the opposite side in unilateral cases or between the operated and nonoperated side in bilateral cases. None of the patients showed facial nerve injury or visible facial scars. CONCLUSION: Within the limitations of a retrospective study, the present study emphasized that optimal management of dislocated bilateral condylar injuries combined with other fractures of the facial skeleton constitute a challenging issue in maxillofacial trauma. Moreover, open reduction and rigid internal fixation of mandibular condylar fractures by an intraoral approach is a technically demanding surgical procedure associated with a high risk of postoperative complications in these injuries.     

Long-term prognosis of BSSO mandibular relapse and its relation to different facial types

The bilateral sagittal split osteotomy (BSSO) has evolved into an effective and preferred surgical procedure for mandibular setbacks. As with all surgical procedures designed to setback the mandible, relapse occasionally occurs after BSSO procedures. Several factors have been suggested to play a contributory role in this relapse. The present study was performed to determine the stability of the mandibular position over the course of long-term observation. Different facial patterns that could potentially be used as predictors of relapse were examined. The study included cases of skeletal mandibular prognathism, with the patient in each case having undergone surgical correction involving a BSSO at least 5 years prior to the study. Lateral cephalograms were analyzed in order to classify facial patterns. Angular and linear cephalometric measurements, consisting of SN-Pogonion angle, SN-occlusal plane angle, and Pogonion depth and height, were compared at 1 year postoperatively and at the long-term follow-up. A significant correlation between facial type and relapse pattern was confirmed at the long-term assessment of prognosis.     

Effect of modified bilateral sagittal split osteotomy on inferior alveolar nerve neurosensory disturbance

The aim of this study was to assess the occurrence of neurosensory disturbance of the inferior alveolar nerve (IAN) following modified mandibular bilateral sagittal split osteotomy (BSSO) that preserves the mandibular inferior border. All patients undergoing BSSO, associated or not with a Le Fort I osteotomy (performed by the same senior operator) between January 2018 and December 2019, were eligible. The modified BSSO consists of a modification of the technique described by Epker: the bony section of the buccal cortex stops 3-4 mm above the basal mandibular edge. While respecting the basilar border, sectioning is then performed up to the gonial angle where bicortical section is finally performed. Sensibility of the labial and chin area was evaluated immediately postoperatively, and at six months and two years of follow up. A total of 140 eligible patients underwent the modified BSSO between January 2018 and December 2019, and 72 were included. Hypoaesthesia was found in 81.9% of the patients (59/72 patients) at initial evaluation. It decreased to 45.8% (33/72 patients) at the six-month examination and to 12.5% (9/72 patients) at the last examination. Four bad splits were recorded. The modified BSSO preserves the inferior border of the mandible and maintains the IAN in the lingual fragment. There is no need to release the IAN, hence its manipulation is reduced and the incidence of IAN postoperative hypoaesthesia is also reduced.     

Positional changes of the masseter and medial pterygoid muscles after surgical mandibular advancement procedures: an MRI study

This study evaluated whether surgical mandibular advancement procedures induced a change in the direction and the moment arms of the masseter (MAS) and medial pterygoid (MPM) muscles. Sixteen adults participated in this study. The sample was divided in two groups: Group I (n=8) with a mandibular plane angle (mpa) <39° and Group II (n=8) with an mpa >39°. Group I patients were treated with a bilateral sagittal split osteotomy (BSSO). Those in Group II were treated with a BSSO combined with a Le Fort I osteotomy. Pre- and postoperative direction and moment arms of MAS and MPM were compared in these groups. Postsurgically, MAS and MPM in Group II showed a significantly more vertical direction in the sagittal plane. Changes of direction in the frontal plane and changes of moment arms were insignificant in both groups. This study demonstrated that bimaxillary surgery in patients with an mpa >39° leads to a significant change of direction of MAS and MPM in the sagittal plane.     

Intraoperative diagnosis of condylar sag after bilateral sagittal split ramus osteotomy

PURPOSE: To evaluate a method to identify condylar sag intraoperatively by clinical examination after bilateral sagittal split osteotomy (BSSO). METHODS: We prospectively studied 184 patients (121 female, 63 male) who had BSSO. The same surgeon operated all patients over a period of 15 months using the same technique. All patients had mandibular advancements. A standard condylar seating technique was used. The occlusion was evaluated at operation and 1 week later. RESULTS: Eighteen patients had an incorrect occlusion diagnosed during the operation after removal of the IMF. Peripheral condylar sag (type II) had developed in three of these patients. In 15 patients central sag was diagnosed. One-week postoperatively, three patients had a malocclusion as a result of condylar sag. CONCLUSION: Meticulous examination of the occlusion and an understanding of the occlusal changes secondary to condylar sag can reliably identify condylar sag intraoperatively. The use of suitable corrective measures during the primary operation can substantially reduce the postoperative complication rate of condylar sag.     

Removal of bicortical screws and other osteosynthesis material that caused symptoms after bilateral sagittal split osteotomy: a retrospective study of 251 patients,and review of published papers

Rigid fixation with either bicortical screws or miniplates is the current standard way to stabilise the mandibular segments after bilateral sagittal split osteotomy (BSSO). Both techniques are widely used and the superiority of one or other method is still debatable. One complication of rigid fixation is the need to remove the osteosynthesis material because of associated complaints. The main aim of this retrospective study was to analyse how often we needed to remove bicortical screws because they caused symptoms after BSSO in our clinic. Review of other published papers also enabled us to investigate the reported rates of removal of screws and miniplates at other centres. The mean (SD) duration of follow-up of 251 patients (502 sites) was 432 (172) days, and the number of bicortical screws removed in our clinic was 14/486 sites (3%). Other methods of fixation were used at 16 sites. We found no significant association between removal of bicortical screws and age, sex, presence of third molars, or bad splits. Published rates of removal of bicortical screws and miniplates are 3.1%–7.2% and 6.6%–22.2% per site, respectively. These findings show that fixation with bicortical screws after BSSO is associated with a low rate of removal of osteosynthesis material. Reported incidences imply a lower rate of removal for screws than for miniplates.     

Comparison of two surgical techniques (HOO vs. BSSO) for mandibular osteotomies in orthognathic surgery—a 10-year retrospective study

Purpose

To retrospectively compare the high-angled sagittal split osteotomy (HOO) and the bilateral sagittal split osteotomy (BSSO) for the correction of skeletal dysgnathias regarding intra- and postoperative complications.

Methods

The electronic medical records of all patients treated with an orthognathic surgery at the Department for Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Frankfurt, Germany, between the years 2009 and 2019 were retrospectively reviewed.

Results

Two hundred ninety-one patients were included. The overall complication rates were 19.78% (BSSO) compared to 12.5% (HOO) (p = 0.14). Significant differences were found regarding the operation time (HOO < BSSO, p = 0.02), material failure (HOO > BSSO, p = 0.04), and early recurrence requiring revision surgery (HOO < BSSO, p = 0.002). The use of a ramus plate significantly reduced the risk of plate failure (2.8% < 13.6%, p = 0.05). More bad splits (p = 0.08) and early sensory disorders (p = 0.07) occurred in the BSSO group.

Conclusion

The HOO presents a possible alternative to the BSSO since newly developed osteosynthesis material significantly reduces the risk of material failure. The BSSO is accompanied by higher risks of developing complications like a bad split and sensory disorders but, however, remains the standard for large anterior–posterior transpositions of the mandible.

     

骨性Ⅱ类错伴颞下颌关节紊乱矫正后的长期稳定性

目的:研究骨性Ⅱ类错伴颞下颌关节紊乱患者在正颌-正畸联合治疗后面型和咬合的长期稳定性。方法:选择10例在本院正颌-正畸中心治疗结束3年以上、资料齐全的骨性Ⅱ类错患者,男2例,女8例,平均年龄(22.3±2.9)岁,治疗结束平均随访期(2.63±1.36)a。治疗方案为术前正畸、正颌手术、术后正畸,手术根据面型测量数据采用双颌手术或上颌手术+颏成形,术中采用坚强内固定。比较治疗前(T0)、治疗结束(T1)和随访结束(T2)的X线头影测量数据,评价颞下颌关节(TMJ)症状量表和MRI的变化。采用SPSS16.0软件包分别对治疗前、随访结束与治疗结束的测量数据进行配对t检验。结果:覆盖平均增加0.62mm,有显著性差异,其余骨性、牙性复发和软组织改建无统计学意义;随访结束UI-NA距离、覆盖和覆变化>2mm占10%,Go-Co长度变化>2mm占20%,软组织颏前点的变化量>2mm占40%,LI-NB距离和颏唇沟的深度变化均小于2mm;所有患者关节症状无加重,MRI未见髁突吸收加重,盘髁关系未见明显改变。结论:骨性Ⅱ类错伴TMD患者通过正颌-正畸联合治疗,能获得面型美观和正常的咬合关系,远期面型结构及咬合关系未见明显复发趋势,未发现TMJ症状加重趋势。     

Changes in condylar long axis and skeletal stability after bilateral sagittal split ramus osteotomy with poly-L-lactic acid or titanium plate fixation

This study was designed to assess skeletal stability after bilateral sagittal split ramus osteotomy (BSSO) and fixation with a poly-l-lactic acid (PLLA) plate, as compared to that after BSSO and fixation with a titanium plate, and to analyze the change in the condylar long axis after these procedures. The study group comprised 40 patients who had mandibular prognathism (20, titanium group; 20, PLLA group). The groups were randomized to show similar distributions of preoperative SNB. All patients underwent BSSO setback by the Obwegeser method. Fixation was done with bent titanium plates or bent PLLA plates, applied in a similar manner. Lateral, frontal, and submental-vertical cephalograms were analyzed preoperatively and postoperatively. The maximum mouth opening range and the incidence of temporomandibular disorders were also evaluated. There was no significant difference in the right condylar angle or width between the two groups, but the left condylar angle and width, gonial angle, and ramus inclination differed significantly between them (P<0.05). SNA, SNB, and ANB were similar in both groups. There was no significant difference between the groups in maximum mouth opening range or temporomandibular disorders. We conclude that the change in condylar angle after BSSO and fixation with a titanium plate is greater than that after BSSO and fixation with a PLLA plate, but skeletal stability related to the occlusion is similar for the two procedures.