The effect of different hybrid rigid internal fixation techniques on the postoperative stability following a mandibular advancement using a bilateral sagittal split ramus osteotomy: A retrospective three-dimensional comparative study

OBJECTIVE

To three-dimensionally evaluate post-operative mandibular stability following bilateral sagittal split ramus osteotomies between hybrid and non-hybrid rigid internal fixation techniques.

MATERIALS AND METHOD

Seventy adults with skeletal class II deformity who underwent bilateral split sagittal osteotomy with mandibular advancement were included. Patients were divided into four groups based on their fixation techniques: hybrid technique (HT) groups I, II, and IV received a 4-hole 2 mm miniplate with either a bicortical screw (BS), additional 2 mm 4-hole miniplate, or two-hole miniplate, while non-HT group III received a 4-hole 2 mm miniplate with four mini-screws (MS). Measurements were taken pre-operatively (T0), immediately postoperatively (T1), and ≥1 year after surgery (T2) using 3D Slicer software.

RESULTS

Age, sex, and follow-up period did not correlate significantly with postoperative relapse or stability. Significant differences were observed in the advancement on the right side between groups II, III, and IV and on the left side between groups I, III, and IV. However, the type of surgical intervention showed no significant effect on postoperative relapse and stability. All groups of fixations showed satisfactory stability with irrelevant relapse (< 2 mm or 2°).

CONCLUSION

The study demonstrated satisfactory and comparable stability among different fixation groups on patients undergoing mandibular advancement following bilateral split sagittal osteotomy. The results highlighted the importance of considering the degree of advancement when planning orthognathic surgery and managing postoperative outcomes.

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion

OBJECTIVES

This study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy.

MATERIALS AND METHODS

Patients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect.

RESULTS

A total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0-T1 (p = 0.02), T0-T2 (p = 0.03), and T0-T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group.

CONCLUSIONS

We found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback.

CLINICAL RELEVANCE

It is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Is it necessary to use bone grafts to prevent defects at the lower border of the mandible after mandibular advancement?-a systematic review

INTRODUCTION

Defects in the lower border of the mandible may represent an aesthetic problem after mandibular advancement in orthognathic surgery. The use of bone grafts has been reported in the literature as a possibility to reduce these defects in the postoperative period.

OBJECTIVE

The objective of this systematic review is to answer the following research question: Is it necessary to use bone grafts to prevent defects at the lower border of the mandible after mandibular advancement?

METHODS

The literature search was conducted on MEDLINE via PubMed, Scopus, Central Cochrane, Embase, LILACS, and Sigle via Open Gray up until December 2020. Five studies were eligible for this systematic review, considering the previously established inclusion and exclusion criteria.

RESULTS

1340 mandibular osteotomies were evaluated, with a mean advance of 8 mm, being 510 with bone graft (42 defects), 528 without graft (329 defects), and 302 with an alternative technique (32 defects). Regarding the type of bone graft used, three articles used xenogenous or biomaterial grafts and two allogenous bone grafts. The results of the meta-analysis showed a reduction in the presence of defects in the bone graft group: OR 0.04, 95% CI = 0.01, 0.19; p = 0.0005, (I2 = 87%; p < 0.0001).

CONCLUSION

The use of bone grafts seems promising in reducing defects in the lower border of the mandible after mandibular advancement. New controlled prospective studies with a larger number of participants are needed to ensure the effectiveness of this procedure.

Evaluation of the lower face enlargement following mandibular osteotomy: Bilateral sagittal split osteotomy (BSSO) vs supra basilar sagittal Split Osteotomy (SBSSO)

INTRODUCTION

The current most common technique for mandibular split is the sagittal split osteotomy described by Obwegeser and modified by Dalpont and Epker. Several studies have shown a lower face enlargement while employing these techniques. The supra-basilar sagittal split osteotomy described in 2017 seems to be an interesting alternative as mandibular angles remain in continuity with the internal valve. The aim of this study was to evaluate lower face enlargement by comparing two techniques: sagittal split osteotomy and supra-basilar sagittal split.

MATERIALS AND METHODS

Cephalograms were analyzed before and after surgery. Bigonial distances (BGD) were measured in frontal cephalograms, ramus length and distances between upper and lower incisors on lateral cephalogram. Control of those measures was also performed by measuring the Nasion-Anterior Clinoid distance and intercanthal distance to assess the comparability and error rate. Finally, a comparison of cephalograms before and after surgery to assess bigonial enlargement, ramus elongation and advancement was performed.

RESULTS

Out of the 69 patients, 18 had a Bilateral Sagittal Split (BSSO) and 52 had a Supra-Basilar Sagittal Split (SBSSO). The error rate and patients' characteristics were the same in the two groups. A statistically significant widening of the bigonial distance with the BSSO in comparison with the SBSSO was found (BGD difference: 5.82 mm (BSSO) vs - 1.47 mm (SBSSO), p < 0,001). A greater ramus elongation with the SBSSO was found (ramus elongation: 1.12 mm (BSSO) vs 5.1 mm (SBSSO)). This study has shown that the supra-basilar sagittal split is an interesting way to avoid the widening of the mandibular angles.

Correlation between mandibular anatomy and bad split occurrence during bilateral sagittal split osteotomy: a three-dimensional study

OBJECTIVES

This study aimed to find out the correlation between different anatomical parameters of the mandible and the occurrence of a bad split in patients who had undergone bilateral split sagittal ramus osteotomy (BSSRO).

MATERIALS AND METHOD

At both the distal roots of the first molar (1) and the retromolar area (2), we measured the distance from the buccal margin of the inferior dental canal (IDC) to the buccal margin of the cortical bone (MCBC), the thickness of both buccal cortical (WBCB) and cancellous bone (WBCA), distance from the superior border of IDC to the alveolar crest (MCAC), buccolingual thickness (BLT), and thickness of cancellous bone (WCA). At the ramus, the distances between the sigmoid notch to the upper part of the lingula (SL) and the inferior border of the mandible (SIBM), the thickness of the ramus at the level of the lingula (BLTR), and the anteroposterior width of the ramus (APWR) were measured. The paired and independent t-tests were used when applicable, and a P-value < 0.05 was considered significant.

RESULTS

MCBC1 showed a significant difference between bad and non-bad split sides (P = 0.037). Both WBCA1 and WBCA2 show the same significant difference (P = 0.023, 0.024). Similarly, WCA1 and WCA2 showed a statistical difference between the bad and non-bad split sides (P = 0.027, 0.036). There were no statistically significant differences between the compared sides of WBCB1, WBCB2, MCAC1, MCAC2, SIBM, APWR, SL, and BLTR.

CONCLUSION

Narrow space between IDC and the buccal cortical margin, along with the decrease in the thickness of both buccal cancellous bone and total cancellous bone at the inferior border of the mandible along the course of SSRO, has been implicated in the occurrence of bad split intraoperatively.

A detailed radiomorphometric analysis of the mandibular foramen, lingula and anti-lingula with a special emphasis on mandibular prognathism

INTRODUCTION

The aim of this study was to evaluate radiomorphometric differences of mandibular foramen (MF), lingula (Li), and anti-lingula (AL) between prognathic and non-prognathic patients, using cone-beam computed tomography (CBCT).

METHODS

A total of 228 3D CBCT images of 57 prognathic and 57 non-prognathic patients were retrospectively evaluated. The distances between MF or Li to occlusal plane (OP), anterior border of ramus (AR), posterior border of ramus (PR), sigmoid notch (SN), gonion (Go) and distances Li to MF were measured. The presence of AL, and the distances to Li were also assessed in both groups.

RESULTS

In prognathic patients the mean distances of MF-AR and Li-PR were lesser, and Li-OP was greater (p < 0.05). However, distances from MF or Li to the other ramal landmarks were similar in both groups (p > 0.05). Presence of AL was found at 53 sides in prognathic and 20 sides in non-prognathic groups (p < 0.05). The horizontal distance of Li-MF was greater in prognathic patients (p < 0.05). On the other hand, there was no difference between groups regarding the horizontal distance of Li-Al, and the vertical distances of Li-MF and Li-AL (p > 0.05).

CONCLUSION

The present study provided valuable data regarding morphological differences of MF-AR, Li-MF and Li-OP, which should be considered in the preoperative assessment of patients with mandibular prognathism. Presence of AL was more common in prognathic patients and mainly located above Li. 3D CBCT applications facilitated assessment of AL and its relationship with Li.

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.

Efficacy of Sagittal Split Fix Plates with Adjustable Slider for Intra-operative Identification and Correction of Condylar Sag in Sagittal Split Osteotomy-a Pilot Study

Aim

To assess the efficacy of sagittal split plate with adjustable slider for intra-operative correction of condylar sag after bilateral sagittal split osteotomy.

Subjects and Methods

Patients reporting for correction of mandibular skeletal deformities for correction with sagittal split osteotomy (SSRO) were enrolled in the study. Simple randomization method was followed for patient allocation. Patients in group A had undergone fixation sagittal split fix plates; in group B, miniplate fixation with monocortical screws was used. Occlusion was the key indicator of condylar sage that was checked at different time frames (intra-operatively T0, immediate T1, 6 months postoperatively T2). Preoperative, immediate and late postoperative (at 6 months and 1-year interval) and lateral cephalometric assessment was used to assess their stability.

Results

Thirty-three patients were enrolled and 20 patients were included in the study. One patient of group A presented with central condylar sag that was identified intra-operatively and addressed immediately. All the patients in group B presented with type 2 peripheral condylar sag that was addressed by inter-maxillary elastics and orthodontics. Two patients in group A presented with mild degree of relapse at 6 months, which was comparable to the control group indicating good stability.

Conclusion

Sagittal split plates appear to be efficacious for intra-operative identification and correction of condylar sag is associated with SSRO.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12663-022-01782-7.

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.

Orthognathic Surgery in Patients with Syndromic Craniosynostosis

Patients with syndromic and nonsyndromic synostosis may have end-stage skeletal discrepancies involving the lower midface and mandible, with associated malocclusion. While orthognathic surgical procedures in this population can be reliably executed, the surgeon must be aware of the unique morphologic characteristics that accompany the primary diagnoses as well as the technical challenges associated with performing Le Fort I osteotomies in patients who have undergone prior subcranial midface distraction.

Piezoelectric versus conventional techniques for orthognathic surgery: Systematic review and meta-analysis

PURPOSE

A systematic review and meta-analysis of the advantages and disadvantages of the piezo surgery comparing with conventional osteotomy in orthognathic surgery.

METHODS

We conducted this systemic review in accordance with the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement. We searched for relevant studies in the PubMed/MEDLINE, Embase databases, Lilacs, Scopus and Science Direct to identify prospective and retrospective studies, compare patient outcomes (intraoperative blood loss, operative time, neurosensory disturbance) after performing orthognathic surgery by conventional saw or piezo-electric device. According to pool individual results we used the mean difference (MD) with the 95% confidence interval (95% CI).

RESULTS

Among three studies that used conventional saw and three studies used piezo-electric device and nine studies used both techniques, the operative time required to perform orthognathic standard procedures was longer using piezo-electric device compared to conventional saw. The results showed that during using the conventional saw to perform orthognathic surgery the amount of the blood loss was higher than the amount while using piezo-electric device (MD -140.4 mL; P = 0.29). based on the studies that evaluated neurosensory disturbance, after 3 months and 6 months respectively, neurosensory disturbance was seen in 23.8% and 23.4% of patient who underwent conventional osteotomy versus 4.3% and 2.4% of the patients who underwent surgery in which piezo surgery was used. Our meta-analysis showed difference in neurosensory disturbance between piezo-surgery and conventional surgery at 3 months (MD -19.5; P = 0.11) and 6 months (MD -21; P = 0.5) postoperatively.

CONCLUSION

Piezo-electric device enabled lower blood loss and higher nerve integrity rates in outcomes according to the complications that associated with orthognathic surgery.

Bone marrow space volume of the mandible influencing intraoperative blood loss in bilateral sagittal split osteotomy: A pilot Study

The aim of this study was to investigate whether the bone marrow space volume of the mandible affects blood loss during bilateral sagittal split osteotomy (BSSO). Sixteen patients who underwent BSSO in our hospital were included in this study. Bone marrow space volume of the mandible was measured by analyzing images from computed tomography. Blood loss during BSSO was measured by weighing gauze, measuring suctioned blood, and adjusting for the volume of irrigation solution used during BSSO. Mean blood loss during BSSO for the 16 patients was 200.5 ml, and patients were divided into: Group I, with less than mean blood loss; and Group II, with greater than mean blood loss. Total bone marrow space volume was significantly greater in Group II (12,450.7 ± 2644.3 mm³) than in Group I (9130.3 ± 3005.8 mm³; P<0.05). A correlation between bone marrow space volume and blood loss during BSSO was suggested, and these results are beneficial for surgeons planning and preparing the orthognathic surgery.

Buccal corticotomy using piezosurgery as a surgical approach for removal of deeply impacted mandibular teeth: An alternative procedure to avoid pitfalls associated with the conventional technique

PURPOSE

To describe and evaluate the use of buccal corticotomy (BC) using a piezosurgical approach for the removal of deeply impacted mandibular teeth.

PATIENTS AND METHODS

The charts of all patients who underwent BC for the removal of impacted mandibular teeth between 2011 and 2019 at the University Hospital of Geneva were reviewed. The primary outcome variables were (1) the indication for the removal of impacted mandibular teeth by BC, (2) complications. Other variables included age, gender, teeth involved, indication for tooth removal and radiological features. Follow-up was at 1, 3, 6 and 12 months, and we noted the status of healing and complications, if any.

RESULTS

Twenty-three mandibular-impacted teeth in 6 patients were extracted using BC (8 third molars, 6 second molars, 1 first molar, 4 second premolars and 4 first premolars). The indications for using the BC approach included (1) deeply impacted teeth closely related to the inferior alveolar nerve (IAN) that runs either lingually or inferior to the dental roots (4 patients); or (2) deeply impacted teeth closely related to the IAN and located anterior to the second molar region (2 patients). No complications were observed during the follow-up period.

CONCLUSION

The present study showed that the BC approach is a valuable method for removing deeply impacted teeth in close proximity to the mandibular canal and is associated with no complications and sound bone healing.

Orthognathic surgery complications: The 10-year experience of a single center

The retrospective cohort study aimed to assess the incidence and characteristics of these complications in patients who underwent orthognathic procedures. Data on the intraoperative and the postoperative complications were extracted from the patients' medical files. Procedures were further subdivided into single-jaw procedures and bimaxillary procedures. A total of 209 orthognathic procedures were carried out in 190 patients. 184 (88%) were performed to treat angle class III malocclusion, while 25 (12%) aimed to treat class II malocclusion. A total of 94 complication events were observed (44.9% of 209 procedures). 22 of them occurred in single-jaw procedures (28.2% of 78 single jaw operations), and 72 occurred in bimaxillary procedures (55% of 131 bimaxillary operations). When compared regarding the type of complication, complication rates were comparable between the study groups with the exception of late-stage malocclusion. A significant difference (p-value = 0.028) in malocclusion incidences between the bimaxillary and single-jaw groups were observed (9 events, 4.3% and zero events, 0%, respectively). The majority of the complications during and following orthognathic surgical procedures are temporary or minor and require little or no treatment at all.

Postoperative neurosensory impairment perception using ultrasonic BoneScalpel and conventional rotary instruments after bilateral split sagittal osteotomy

PURPOSE

Although bilateral sagittal split osteotomy (BSSO) is the most widely used surgical technique for the correction of mandibular dentofacial anomalies, it is associated with lesion of inferior alveolar nerve (IAN) and unwanted neurosensory disorders. The aim of this study was to document the perception of changes in sensitivity and mean recovery time after BSSO, using an ultrasonic BoneScalpel versus the conventional rotary instruments.

PATIENTS AND METHODS

This retrospective observational study included all patients with diagnosis of skeletal anomaly who underwent advancement or setback BSSO of less than 10 mL, using the ultrasonic osteotome or conventional rotary instruments. The patients were operated on at the Hospital Universitario Clínica San Rafael, Bogotá Colombia, between 2017 and 2018. The primary predictor variable was the osteotomy technique. The primary outcome was the presence or absence of postoperative sensory alteration, whereas secondary outcomes were time of appearance and recovery, affected anatomical region, laterality, and disturbance in daily activities. Data were analyzed using Chi-square, Mann-Whitney U, and Fisher's exact test.

RESULTS

Data of 38 patients were retrieved, of which 23 were operated with BoneScalpel and 13 with the conventional technique. Twenty patients were women and 18 were men. All patients reported experiencing at least one type of sensory disturbance immediately after the surgical procedure. There was a significant difference (p = 0.0001) in the time that the alteration was present between the two groups, in favor of the BoneScalpel group. The chin and the lower lip were the anatomical regions with the greatest alteration in sensitivity and persistence of it.

CONCLUSIONS

The results of this study indicate that BoneScalpel is effective in performing BSSO. They also suggest that it may reduce the occurrence of nerve damage during BSSO, although more research on this topic is required.

A new 3D analysis on displacement of proximal segment after bilateral sagittal split osteotomy for class III asymmetry

OBJECTIVES

We aimed to quantify the displacement of the proximal segment after bilateral sagittal split osteotomy in patients with class III asymmetry and evaluate if the displacement was related to the movement of the distal segment.

MATERIAL AND METHODS

Forty adults with class III asymmetry corrected by bimaxillary surgery were studied. Cone-beam computed tomography taken before and 1 week after surgery was used to measure the displacement of proximal segments and movement of the distal segment in terms of translation and rotation. The relationship between the displacemnt of the proximal segment and the movement of the distal segment was evaluated.

RESULTS

After surgery, the deviated proximal segment was displaced forward and to the deviated side, rotated downward, tilted, and turned to the opposite side. The opposite proximal segment was displaced forward and rotated downward. The roll rotation of the proximal segment was correlated with the left/right movement and roll rotation of the distal segment.

CONCLUSION

Early after orthognathic correction for class III asymmetry, the deviated proximal segment was displaced in a direction favorable for correction of asymmetry. The roll rotation of the proximal segment was affected by the transverse movement and roll rotation of the distal segment.

CLINICAL RELEVANCE

Knowledge of the ability and limitation of the proximal segment rotation improves the virtual simulation.

Prospective Analysis of the Swallowing Reflex After Sagittal Split Osteotomy: Comparison with Normal Volunteers

The aim of this study was electromyographic description of changes in swallowing before and after bilateral sagittal split ramus osteotomy. In this prospective study, twenty-eight patients were divided into 3 groups according to the occlusion pattern: Group I (Angle Class III), Group II (Angle Class II), and Control (Class I). Serial cone-beam computed tomography analyses and electromyographic data were collected preoperatively, 1st and 6th months after setback surgery in Group I, and advancement surgery in Group II. Swallowing reflex with 3-20 ml water bolus were studied. Patients were further divided into two subgroups according to the magnitude of relapse. The mean setback of the mandible was 4.62 ± 1.92 mm in Group I, and the mean advancement was 4.19 ± 2.00 mm in Group II. Mandibular relapse rate was 17.40%. Oral preparation phase shortened after surgery in both study groups. Two subjects in Group II and one in Group I had piecemeal deglutition, and two of them became normal postoperatively. Most of the swallowing durations of the relapsed cases were longer than those of stabilized patients. Important clinical considerations are as follows: the oral preparation period becomes shorter after surgery; piecemeal deglutition may disappear after treatment; and individuals with a longer oral period and piecemeal deglutition may have increased tendency to skeletal relapse. This multidisciplinary study enhances our understanding of the adaptive response to the swallowing reflex after orthognathic surgery and provides novel insight into the association between the submental muscle activity and relapse in orthognathic patients.

Comparison of postoperative paresthesia after sagittal split osteotomy among different fixation methods: a one year follow-up study

Objectives

Postoperative paresthesia is a common complication after sagittal split osteotomy (SSO). This study aimed to compare paresthesia among different fixation methods one year postoperative.

Materials and Methods

This prospective cohort study assessed subjects in four groups: class II with miniplate fixation (Group 1), class II with three-screw fixation (Group 2), class III with miniplate fixation (Group 3), and class III with three-screw fixation (Group 4). Paresthesia was evaluated one year postoperative based on a 0-10 visual analogue scale. Pearson correlation was used to evaluate associations of age and mandibular movement with paresthesia. ANOVA was used to compare paresthesia among groups.

Results

A total of 80 subjects were enrolled, with 20 subjects in each of the four groups. The Pearson correlation test demonstrated a significant correlation between mandibular movement and paresthesia (P=0.001). Comparison of paresthesia among the groups showed significant differences among groups 1 and 2, 2 and 3, and 3 and 4 (P<0.05).

Conclusion

The three-screw fixation method led to more paresthesia one year postoperative compared with miniplate fixation. In addition, the magnitude of mandibular movement had a positive correlation with paresthesia.

Optimizing mandibular sagittal split of large maxillomandibular advancements for obstructive sleep apnea: patient and surgical factors

OBJECTIVES

Maxillomandibular advancement (MMA) confers consistent and high rates of surgical success for obstructive sleep apnea (OSA). In the era of value-based medicine, identifying factors that affect the stability of rigid fixation and allow rapid return to function are important targets for improvement. The aim of this study was to identify patient and surgical factors associated with mandibular sagittal split outcomes associated with optimal postoperatively skeletal stability.

STUDY DESIGN

Retrospective cohort study.

MATERIALS AND METHODS

Forty-six subjects (43 males and 3 females) with postoperative CT scans including three-dimensional reconstruction from which mandibular split patterns could be analyzed were enrolled. Patient factors (age and polysomnographic measures) and surgical factors (extent of osteotomy prior to controlled fracture) were assessed. Outcome measures include (1) bone thickness for rigid fixation and (2) area of passive bony overlap after advancement.

RESULTS

Age and severity of disease did not contribute significantly to optimal mandibular split patterns. For optimal area for passive bony overlap and thickness of buccal and lingual plates for rigid fixation, the most important factors are related to surgical technique.

CONCLUSIONS

Anterior osteotomy just to the midline of inferior border and horizontal osteotomy to the mandibular foramen are associated with split patterns that result in optimal rigid fixation and passive bony overlap for OSA patients undergoing MMA.

CLINICAL RELEVANCE

Optimal surgical technique has the most significant influence in allowing rapid return to function after MMA in patients with OSA.

Pulpal and Periodontal Tissues Changes Associated with Le Fort I and Sagittal Split Ramus Osteotomies: A review

Introduction:

Le Fort I and sagittal split ramus osteotomies are the most commonly performed orthognathic surgery procedures on the maxilla and mandible, respectively.

Techniques:

Despite progress in the techniques, these procedures may still be associated with morbidity, expressed as inflammation, inadequate bony union, periodontal damages or in extreme cases even total bone loss.

Discussion:

Through a comprehensive review of the literature, the influences of maxillary and mandibular surgery on Pulpal Blood Flow (PBF), pulp sensitivity and pulp vitality are examined. Moreover, adverse effects of maxillary surgery on tooth color and periodontal tissues are also reported. The effects had a variety of expression. Concerning maxillary surgery, some studies showed an initial increase in PBF followed by a decrease to the baseline or even lower levels after 1-3 months. Other studies found an initial decrease in PBF followed by an increase soon after. There were also studies that showed no significant PBF changes, in contrast.

Conclusion:

Concerning mandibular surgery, a recent study showed a decrease in PBF immediately after sagittal split ramus osteotomy. Some authors detected tooth discoloration of maxillary teeth after Le Fort I osteotomy. Root resorption and root injury were also detected, but were of minor significance. Usually, these adverse effects derive from injury of the vessels of the palatal pedicle. This pedicle should be maintained intact for the avoidance of blood flow impairments. In addition, the descending palatine artery should be protected during maxillary surgery procedures in order to maintain the highest possible blood flow on the maxillary teeth.

Hypoesthesia associated with mandibular movement after sagittal split ramus osteotomy

PURPOSE

This retrospective study investigated the relationship between the degree of neurosensory disturbance (NSD) and mandibular movement distance after sagittal split ramus osteotomy (SSRO) and assessed sensory recovery.

METHODS

Lower lip hypoesthesia was evaluated at 1 week, 1 month, and 2 months after SSRO in 38 patients categorized according to the distance of mandibular movement: S group (0-7 mm; n = 17, 4 males and 13 females) and L group (7-14 mm; n = 21, 7 males, 14 females). Symptoms were evaluated by visual analog scale (VAS), tactile-threshold (SW) test, static 2-point discrimination (s-2PD) test, and current perception threshold (CPT) test.

RESULTS

The two groups did not differ significantly in gender and age. The Aβ fiber results of the CPT test differed significantly between the groups at 1 week and 1 month postsurgery (P < 0.05). There were no significant differences between the groups throughout the period in terms of VAS, SW, s-2PD, Aδ fiber, and C fiber of CPT.

CONCLUSIONS

Post-SSRO, the incidence of NSD in terms of tactile sensation may be greater in the L group early postoperatively. This may assist surgeons in explaining postoperative hypoesthesia to patients preoperatively.

Vertical ramus elongation and mandibular advancement by endobuccal approach: Presentation of a new osteotomy technique

INTRODUCTION

Several surgical procedures have been proposed for the treatment of hyperdivergent dentoskeletal deformities. We propose a new osteotomy technique allowing for lengthening and advancement of the mandibular ramus by intra-oral approach.

SURGICAL PROCEDURE

This technique differs from the conventional sagittal split osteotomyin that which the anterior osteotomy line is not continued until the basilar edge but stopped 5-6mm above it. Cutting of the pterygomasseteric sling is systematically done allowing for the lowering of the mandibular angle. Osteosynthesis is performed by transjugal and intra-oral approaches, using two adjustable miniplates. Our supra-angular technique allows for both elongation of the ramus and advancement of the mandible. Unlike the vertical ramus osteotomy proposed by Caldwell-Letterman, external incision and intraoperative cervical hyperextension are not required.

The use of patient-specific implants in orthognathic surgery: A series of 30 mandible sagittal split osteotomy patients

PURPOSE

Virtual surgery combined with patient-specific saw and drill guides and osteosynthesis materials are rapidly spreading from reconstructive surgery to orthognathic surgery. Most commercial partners are already providing computer-aided design and computer-aided manufacture (CAD/CAM) wafers and patient-specific saw guides. Clear benefits have been demonstrated for custom-made drill guides combined with individually designed three-dimensional (3D) printed patient-specific implants (PSI) as a reposition and fixation system in Le Fort I osteotomy.

MATERIALS AND METHODS

We treated 30 patients who underwent bilateral sagittal split osteotomy (BSSO) due to class II dento-skeletal deformities with the additional use of drill guides combined with PSI as a fixation and positioning system.

RESULTS

The PSIs fitted bilaterally with total precision in 11 of the 30 patients. In 17 patients, the PSIs were used with some modifications. In 2 of 30 patients, the PSIs could not be used as a fixation due to misfit.

CONCLUSION

Due to unpredictable fitting, the use of PSIs with drill guides alone in BSSO without wafers cannot be recommended. Further studies are needed to evaluate the interfering parts, which seem to be related to condylar positioning and bony interferences at the osteotomy sites.

Are there risk factors for osseous mandibular inferior border defects after bilateral sagittal split osteotomy?

PURPOSE

Bone defects of the inferior mandibular border (osseous inferior border defects) can cause unesthetic postoperative outcomes after bilateral sagittal split osteotomy (BSSO). The aim of this study was to estimate the frequency of osseous inferior border defects after BSSO and to identify risk factors for this complication.

MATERIALS AND METHODS

This retrospective study included consecutive patients who underwent BSSO for mandibular retrognathia. The primary outcome was the presence/absence of osseous inferior border defects. Predictors included the mandibular movement, rotation of the occlusal plane, postoperative proximal segment position, pattern of lingual fracture, occurrence of bad split, and presence of third molars.

RESULTS

The study sample consisted of 200 patients and had a mean follow-up of 13 months. The mean mandibular advancement and rotation was respectively 5.8 mm and 5.4° clockwise. Osseous inferior border defects were present in 7.0% of splits and in 12.5% of patients. Significant risk factors for inferior border defects included increased advancement, increased clockwise rotation, cranial rotation of the proximal segment, and a split originating in the lingual cortex.

CONCLUSION

In conclusion, osseous inferior border defects occur significantly more often in cases with large mandibular advancement, increased clockwise rotation of the occlusal plane, malpositioning of the proximal segment, and a split originating in the lingual cortex.

Morphological features of the mandible as predictors for neurosensory disturbances after bilateral sagittal split osteotomy

This retrospective study aimed to identify anatomical predictors of neurosensory disturbance (NSD) after bilateral sagittal split ramus osteotomy (BSSO) by evaluating the morphology of the mandible on lateral cephalograms (LCs) and orthopantomograms (OPTs). The LCs and OPTs of 142 patients who underwent BSSO were reviewed. The influence of the mandibular angle was assessed on LCs, while the following morphological landmarks and subsequent measurements were analysed on OPTs: vertical and horizontal positions of the lingula, ramus width, mandibular body height, mandibular canal position and mandibular angle length. Post-operative NSD (hypoaesthesia) was considered permanent when objective tests or subjective evaluations indicated altered sensation one year after BSSO. Generalised linear mixed models were used to take into account the repeated measurement design (left and right measurements within one patient). Hypoaesthesia was present in 10.6% of the patients (5.6% of sites). After adjusting for age, a small mandibular body height was found to significantly increase the risk of hypoaesthesia. The other measurements showed no significant association with hypoaesthesia. These findings show a relationship between mandibular morphology and hypoaesthesia after BSSO and can aid surgeons in pre-operative assessments of the risk of NSD. Further research is needed to identify risk factors for NSD based on mandibular morphology.

Unusual cause of iatrogenic anterior open bite after bilateral sagittal split mandibular advancement osteotomy

We describe a case of anterior open bite after bilateral sagittal split mandibular advancement osteotomy. The discrepancy in height between the proximal and distal segments at the osteotomy sites damaged the soft tissue and caused bony interferences. Removal of the maxillary third molars and bilateral removal of bony interferences of the distal segments using a bur led to full resolution and a good orthognathic outcome on follow-up.

Lower-level laser therapy improves neurosensory disorders resulting from bilateral mandibular sagittal split osteotomy: a randomized crossover clinical trial

Bilateral sagittal split osteotomy (BSSO) is a technique commonly used to correct mandibular disproportion but many patients experience hypoaesthesia of the inferior alveolar nerve (IAN). The purpose of this study was to verify the effectiveness of using a low-level laser therapy protocol after BSSO. The 10 patients in our study, who underwent BSSO with Le Fort I osteotomy and had low-level laser therapy on one side of the jaw, were evaluated over a period of 60 days. The data for the treated and non-treated sides were compared post-operatively. At 15, 30 and 60 days after surgery, when sensitivity was recovered on both sides. On the treated side, recovery was faster and was almost complete at the time of the last evaluation. We suggest that this lower-level laser therapy protocol can improve tissue response and accelerate the recovery of neurosensory disorders following BSSO. (NCT01530100).

Management of superolateral dislocation of the mandibular condyle: a retrospective study of 10 cases

INTRODUCTION

Superolateral dislocation of the mandibular condyle (SDMC) is rarely described. The best treatment for superolateral dislocation of the fractured mandibular condyle (SDMC) is debated. This study investigated selection of the timing and techniques used in treating these fractures.

PATIENTS AND METHODS

A retrospective clinical study was conducted on clinical data from 10 SDMC patients. Maximum mouth opening and occlusal relationships were compared following treatment using different techniques.

RESULTS

The 10 patients were followed for 6-25 months. Patients who had dislocation for less than 1 week had condylar reduction and rigid internal fixation of the fractures. Mandibular sagittal split ramus osteotomy and articular reduction and fixation were performed in seven cases. Postoperative mouth opening and occlusal relationships were satisfactory in all patients with the exception of one case with mouth opening of only 27 mm.

CONCLUSIONS

For all patients with superolateral dislocation, our first approach was to reduce the bone stump through surgery. When the dislocated joint had become adherent to the surrounding tissues and ankylosis developed, mandibular sagittal split ramus osteotomy was performed with good results.

A Morphometric Study of the Maxillary Artery and Lingula in Relation to Mandibular Ramus Osteotomies and TMJ Surgery

OBJECTIVES

Mandibular osteotomies and resection of the temporomandibular joint (TMJ) ankylosis are the mostly performed surgical procedures in the infratemporal fossa, which is in close proximity with the main trunk of the maxillary artery (MA). It is imperative to avoid the trunk or branches of the maxillary artery, otherwise, massive intraoperative or postoperative hemorrhage may develop. The goal of the study was to investigate the position of the maxillary artery in the infratemporal fossa and the lingula of the mandible.

METHODS

Significant landmarks were selected on the mandibles of formalin fixed cadavers, and the distances were measured between the maxillary artery and the bony landmarks with a digital caliper.

RESULTS

The average distances between the MA and the articular eminence, the medial cortex of the mandibular ramus, the inferior border of the pterygoid fovea and the mandibular notch were 1.67+/-0.48 mm, 5.38+/-2.47 mm, 16.84+/-1.74 mm, 2.94+/-0.52 mm, respectively. Course pattern of the MA at the subcondylar level was also mapped. In order to determine the position of the lingula, the average distances between the tip of the lingula and the mandibular notch, the inferior border of the ramus, the anterior margin of the ramus and posterior margin of the ramus were measured and found as 15.4+/-2.1 mm, 49.5+/-4.3 mm, 18.1+/-2.7 mm, 16.6+/-2.5 mm, respectively. No significant differences were found between the right and left sides, for all parameters.

CONCLUSIONS

The studied parameters will assist and navigate clinicians to determine the anatomic proximity to the maxillary artery, and, minimize the risk of damaging the vessel.

Stability of the mandible after bilateral sagittal split osteotomy: Comparison between positioning screws and plate

Relapse is one of the complications of orthognathic surgery. In this study, we compared the stability of mandibular bilateral sagittal split osteotomy by using two different methods of fixation. In Group 1, eight patients with prognathic mandible underwent BSSO and set back average of 6.0 mm. The method of fixation was positioning screws. In Group 2, eight patients with prognathic mandible underwent BSSO and set back average of 6.0 mm. The method of fixation was plate and monocortical screws. In Group 3, eight patients with retrognathic mandible underwent BSSO and advancement average of 6.0 mm. The method of fixation was positioning screws. In Group 4, eight patients with retrognathic mandible underwent BSSO and advancement average of 6.0 mm. The method of fixation was plate and monocortical screws. The results showed in terms of advancement that there was no significant difference between the groups after one year. However, in terms of set back, this study showed significant difference.