Risk factors and prevention of bad splits during sagittal split osteotomy

Modification of Sagittal Split Osteotomy in Class II Asymmetry: Optimizing Bone Contact between Proximal and Distal Segments

BACKGROUND

Computer-assisted surgical simulation (CASS) allows more precise orthognathic surgery. However, few studies have evaluated associations between CASS-designed bilateral sagittal split osteotomy (SSO) and bone contact surface in class II mandibular asymmetry. This study aims to evaluate the effects of using computer-assisted simulation and design modification of SSO to improve bony contact in skeletal class II asymmetry.

METHODS

This retrospective analysis reviewed 28 patients with class II asymmetry who underwent orthognathic surgery, including 15 with modified SSO (group CS) and 13 with conventional SSO (group C). Modified SSO was designed under CASS. Operative characteristics, postoperative outcomes, and complications were collected and compared between the two groups.

RESULTS

Bony contact was found at the distal end of the proximal segment in all group CS patients, while bone gap was noted in all group C patients ( P < 0.05). Moreover, bone graft was used in four group C patients but was not used in all cases in group CS patients ( P < 0.05). A trend toward lower operative time or perioperative bleeding was noted in group CS, but without statistical significance. After 1-year follow-up, inferior alveolar nerve disturbances were noted in two group CS patients and one group C patient. Palpable bone gap with uneven jaw line was noted in two group C patients 1 year after surgery and one patient received fat graft treatment.

CONCLUSION

The simulation-based SSO modification provides appropriate contact surface and eliminates the bone gap between proximal and distal segments in class II asymmetry.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Successful rehabilitation after multiple severe complications following orthognathic surgery: a case report

BACKGROUND

Complications of orthognathic surgery are quite rare, but they cause suffering in affected individuals. The range of complications is broad and includes both hard and soft tissue.

CASE PRESENTATION

We here present a case of a fully healthy woman without signs of impaired healing capacity. The patient underwent bimaxillary orthognathic surgery and experienced multiple complications both peri- and post-operatively. During the post operative period, the patient also suffered from soft tissue complications after an orthopaedic injury. Therefore, we referred the patient to her general practitioner for further medical investigation. We also present the result after restorative surgery and endodontic and prosthodontic treatment resulting in a successful rehabilitation.

CONCLUSION

This case report clearly shows the need for a good collaboration between different odontological and medical fields to achieve a good and predictable result. In situations where normal healing processes do not occur, in-depth analysis must be carried out.

HIGHLIGHTS

Orthognathic surgery affects soft and hard tissue which can result in adverse healing and complications. It is of great importance to follow up performed surgery to see late complications. Be restrictive with early re-operations when there are signs of necrosis. Always use a multidisciplinary approach when handling complications after surgery.

Does osteotomizing the lower border of the mandible affect the lingual split pattern in a sagittal split ramus osteotomy?

AIM

The purpose of this study was to evaluate the effect of adding a fourth osteotomy at the lower border of the mandible on the lingual cortical fracture pattern in bilateral sagittal split ramus osteotomies.

PATIENTS AND METHODS

The sample of the study consisted of 20 patients (12 male and 8 female, with a mean age of 26.79 ± 7.12 years) with mandibular deformities who needed bilateral sagittal split ramus osteotomy. One side underwent a traditional sagittal split ramus osteotomy, and the procedure was modified on the other side by adding a 1 cm horizontal osteotomy at the lower border of the mandible, just distal to the caudal end of the vertical buccal osteotomy cut. A 3D CBCT was used to identify the split pattern.

RESULTS

In the total sample, 40% of the lingual splits ran vertically toward the lower border of the mandible (LSS1), 20% of the splits passed horizontally to the posterior border of the mandible (LSS2), 32.5% of the splits took place along the inferior alveolar canal (LSS3), and 7.5% of the splits were unfavourable fractures (LSS4). On the inferior border osteotomy sides, the distribution of LSS1, LSS2, LSS3, and LSS4 was 10 (25%), 6 (15%), 4 (10%), and 0 (00), respectively. Their distribution on the sides without inferior border osteotomy was 6 (15%), 8 (20%), 13 (32.5%), and 3 (7.5%), respectively. Statistical analysis revealed a significant difference between the two groups (p < 0.05).

CONCLUSION

Inferior border osteotomy tends to direct the lingual split fracture line toward the lower and posterior borders of the mandible and minimizes bad splits; however, further studies are needed to confirm our findings.

Computed tomography evaluation of risk factors for an undesirable buccal split during sagittal split ramus osteotomy

Sagittal split ramus osteotomy (SSRO) sometimes induces an irregular split pattern referred to as a bad split. We investigated the risk factors for bad splits in the buccal plate of the ramus during SSRO. Ramus morphology and bad splits in the buccal plate of the ramus were assessed using preoperative and postoperative computed tomography images. Of the 53 rami analyzed, 45 had a successful split, and 8 had a bad split in the buccal plate. Horizontal images at the height of the mandibular foramen showed that there were significant differences in the ratio of the forward thickness to the backward thickness of the ramus between patients with a successful split and those with a bad split. In addition, the distal region of the cortical bone tended to be thicker and the curve of the lateral region of the cortical bone tended to be smaller in the bad split group than in the good split group. These results indicated that a ramus shape in which the width becomes thinner towards the back frequently induces bad splits in the buccal plate of the ramus during SSRO, and more attention should be paid to patients who have rami of these shapes in future surgeries.

Management of A Bad Split Complication: A Systematic Review

Introduction:

Bad split is one of the well-known intra-operative complications that occur during the bilateral sagittal split osteotomy (BSSO) procedure, which is a rehabilitation procedure for patients with mandibular deformities. The prevention of further post-surgery complications required sufficient management of bad split complications.

Objective:

This study aimed to analyze the management of bad split complications during a BSSO procedure.

Methods:

The literature review was conducted in the form of library research in the field of bad split complications' management by a BSSO based on the Preferred Reporting Items for Systematic Reviews (PRISMA). Related studies were found through using a manual search using Pubmed, ScienceDirect, Ebscohost, Scopus, Medline, Embase, and Web of Science, among other search engines. The inception of incorporation standards, the process of data extraction, and the determination of the risk of bias were carried out by the authors. The process of data screening was conducted by applying the inclusion and exclusion criteria.

Results:

This paper systematically reviewed seven related studies, four of which were case series and two of which were cross-sectional. The utilization of additional osteosynthetic plates was revealed throughout the extraction process as the most acquainted course of action to manage the bad split complications during the BSSO procedure.

Conclusion:

The osteosynthetic plate and miniplate application with bicortical or monocortical screws were exposed as the most used treatment for bad split complications.

Risk Factors Analysis for Different Types of Unfavorable Fracture Patterns During Sagittal Split Ramus Osteotomy: A Retrospective Study of 2008 Sides

PURPOSE

To summarize unfavorable fracture patterns during sagittal split ramus osteotomy (SSRO) and investigate the association with influencing factors.

MATERIALS AND METHODS

We conducted a retrospective analysis of 1007 patients with 2008 sides of SSRO and classified unfavorable fracture patterns into three types: fracture lines involving the sigmoid notch, condylar process, or coronoid process (Type A); fracture lines extending from the posterior border of the mandibular ramus to the mandibular body or the anterior border of the ramus (Type B); and unfavorable fractures located in the anterior horn of the proximal segment with free fragment (Type C). Logistic regression analysis was used to evaluate factors influencing unfavorable fracture patterns, including sex, age at the time of operation, class of occlusion, presence of the third molar, uni- or bi-maxillary surgery, and the distance from the mandibular canal to the buccal cortex.

RESULTS

The distance from the mandibular canal to the buccal cortex was significantly associated with unfavorable fracture patterns during SSRO. The presence of third molars was significantly associated with Type A fractures. The distance from the mandibular canal to the buccal cortex was significantly lower in Type B fractures.

CONCLUSION

We found that the influencing factors for unfavorable fracture patterns varied. Clinicians should pay specific attention to patients with factors for each unfavorable fracture pattern during SSRO.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Dal Pont vs Hunsuck: Which Technique Can Lead to a Lower Incidence of Bad Split during Bilateral Sagittal Split Osteotomy? A Triple-blind Randomized Clinical Trial

BACKGROUND

We aimed to assess the incidence of bad split fractures during Bilateral Sagittal Split Osteotomy (BSSO) mandibular setback surgery using Dal Pont and Hunsuck techniques.

METHODS

All healthy adults with skeletal class III discrepancy, who were candidates for mandibular setback surgery were enrolled in this randomized clinical trial in the Maxillofacial Surgery Department of Qaem Hospital, Mashhad, Iran; from 2018-2020. These patients were randomly divided into two equal groups; one group underwent BSSO using Dal Pont osteotomy while the Hunsuck osteotomy was employed for the other group. A bad split fracture which identified through intra-operative clinical and postoperative radiographic examination was the outcome variable. The significance level was set at 0.05 using SPSS 16.

RESULTS

Overall, 104 consecutive patients, comprising of 52 (50%) males with an average age of 23.09±3.08 were recruited. The average duration of osteotomy and splitting was reported to be 22.74±3.06 min. 10 bad split fractures (9.62%) were observed; 7 of which occurred in the Dal Pont group and 3 in the Hunsuck group. However, this difference was not significant. In 80% of the cases, bad split osteotomy occurred in the proximal segment, while this finding was identified in the distal segment in 20% of cases. The average duration of osteotomy and splitting was significantly longer in the Dal Pont group (P<0.001).

CONCLUSION

The duration of osteotomy and splitting is much shorter when the Hunsuck technique is employed, and the incidence of unfavorable fractures is also less compared to the Dal Pont osteotomy technique.

Classification and Clinical Treatments for Unfavorable Fractures of the Proximal Segment in Sagittal Spilt Ramus Osteotomy: A Retrospective Study of 964 Cases

ABSTRACT

Unfavorable fractures in sagittal split ramus osteotomy are hard to manage. The aim of this study is to develop a new classification method for unfavorable fractures of the proximal segment to guide clinical managements. After reviewing 964 cases of sagittal split ramus osteotomy, we found that the unfavorable fractures can be divided into 3 types: mandibular ramus transverse fractures (Type 1), bad fractures accompanied by free fragments (Type 2), and unexpected separation patterns without free fragments (Type 3). We calculated the incidence of each fracture type and provided instructions for their corresponding treatments. Thirty-six patients suffered from unfavorable fractures (7.4% of patients), among which 32 patients had unilateral fractures and 4 patients had bilateral fractures. There were 2 Type 1 fractures (0.2% of split sites), 8 Type 2 fractures (0.8% of split sites), and twenty-six Type 3 fractures (2.3% of split sites). Type 1 unfavorable fractures are difficult to deal with, but Types 2 and 3 are generally manageable and they have no significant impact on the final outcomes. The new classification can effectively guide treatment strategies for unfavorable fractures. Severe cases of unfavorable fractures are rare, and most unfavorable fracture cases have a positive prognosis if correctly treated in time.

Postoperative CT findings of orthognathic surgery and its complications: A guide for radiologists

Orthognathic surgery is the standard procedure to correct congenital, developmental, or acquired dentofacial deformities. The maxillomandibular relationship corrected by orthognathic surgery can improve facial esthetics, masticatory function, articulation, and breathing. The most common types of osteotomies include the combination of Le Fort I osteotomy, bilateral sagittal split mandibular ramus osteotomy, and genioplasty. High-resolution low-dose computed tomography is useful for evaluating the facial skeleton and soft tissues after surgery as well as for depicting a variety of possible complications. This article reviews the postoperative imaging findings of the most common orthognathic surgeries and their potential complications on multidetector-row computed tomography.

Comparative assessment of osteotomy cut using bur and saw for bilateral sagittal split osteotomy of mandible: a prospective clinical study

PURPOSE

To compare the intraoperative utility of bur and saw and to examine the pattern of lingual split during bilateral sagittal split osteotomy of mandible.

MATERIAL AND METHODS

This study prospectively compares the intraoperative utility of bur and saw in bilateral sagittal split osteotomy as split-mouth model. Study includes 16 patients (representing 32 sagittal split osteotomies) divided into two groups. The procedure to be performed was explained to the patient, followed by written informed consent. The institutional ethical committee approved the clinical study and all subjects gave informed consent.

RESULTS

We found that the ease of handling of the bur was good compared to saw. The duration required for completion of osteotomy using bur was less compared to saw.

CONCLUSIONS

The use of surgical drills and burs is still the gold standard in most developing nations and countries in transition like India. Depending upon the expertise of the surgeon, availability of precise dissecting instruments, one can go with either of the instrument for BSSO.

Does the Presence of Impacted Mandibular Third Molars Increase the Risk of Bad Split Incidence During Bilateral Sagittal Split Osteotomy?

BACKGROUND

The possibility of mandibular bad spilt might happen during bilateral sagittal split osteotomy (BSSO). This study investigated the effect of impacted mandibular third molars on bad spilt incidence during BSSO.

METHODS

Totally, 140 patients under 40 years old who were candidates for BSSO surgery due to class 3 skeletal discrepancy were divided randomly into two equal groups. The impacted mandibular third molars were presented in one group during BSSO (Exposed), and the third molars were removed at least six months before surgery for the other group (Unexposed). All cases underwent BSSO using the same technique by a single surgeon. A bad split was diagnosed by inter-operative clinical examination and postoperative panoramic radiography.

RESULTS

Four bad split occurrences were observed including three patients in the group which impacted mandibular third molars were presented and one patient in the group without impacted mandibular third molars. The incidence of bad fracture in the exposed group was 3.7 times more than the unexposed group. The incidence of the bad fracture in exposed group was 3.7 times more than unexposed group. The chance of fractures in females was 1.7 times higher than males. With one year addition to the patient's age, chance of fracture increased 0.985 times more.

CONCLUSION

Overall incidence of bad split fracture in presence of mandibular third molars in females and at older ages increased during BSSO. The extraction of impacted mandibular third molars, six months before the BSSO is recommended to prevent the bad split incidence during the operation.

Risk factors for bad splits during sagittal split ramus osteotomy: a retrospective study of 964 cases

To identify the potential risk factors for bad splits, we calculated the incidence of bad splits from 484 patients with 964 cases of sagittal split ramus osteotomy (SSRO) and investigated the association between the occurrence of bad splits and risk factors such as gender, patients' age, class of occlusion, unimaxillary or bimaxillary surgery, presence of the lower third molar, thickness of the ascending ramus, and the distance from the mandibular canal to the buccal cortical bone. The results showed that 40 sides (4.149%) with bad splits occurred in 36 patients (7.438%). The mean (SD) gap width from the canal to the buccal cortex for the bad split group, at 4.02 (1.20)mm, was narrower (p=0.003; OR=0.689; 95% CI=0.538 to 0.882) than the normal split group 4.80 (1.72)mm. On the contrary, no statistical significance (p>0.05) was detected between the patients with bad splits and those with normal splits for the other factors. In conclusion, SSRO patients with narrower distances from the mandibular canal to the buccal cortex were more prone to bad splits. More attention should be paid to patients with this risk factor during future surgeries.

Density of the mandibular ramus (cancellous:cortical bone volume ratio) as a predictor of the lingual fracture pattern in bilateral sagittal split osteotomy

The aim of this retrospective cohort study was to evaluate the relative amount of cancellous bone in the mandibular ramus as a predictor of lingual fracture patterns after bilateral sagittal split osteotomy (BSSO). The study including 78 consecutive patients (156 osteotomy sites). In preoperative cone-beam computed tomographic (CT) scans, the volumes of cancellous and cortical bone in the BSSO surgical field were estimated. Patients were divided into two groups based on the cancellous:cortical bone ratio. We studied postoperative cone-beam CT scans for lingual fracture lines and subcategorised them according to the lingual split scale (LSS). Generalised linear mixed models (GLMM) were estimated to evaluate the association between the cancellous:cortical bone ratio and the lingual fracture pattern. There was a significant association between the cancellous:cortical bone ratio of the mandibular angle and the lingual fracture pattern after BSSO. Mandibular angles with a relatively small amount of cancellous bone showed significantly more LSS3 fracture lines (OR=1.990, 95%CI 1.043 to 3.796, p=0.043). These mandibular angles also showed more unfavourable fractures (LSS4), although this was not significant (OR=2.352, 95%CI 0.748 to 7.392, p=0.143). The relative amount of cancellous bone in the mandibular angle is significantly associated with the lingual fracture line after BSSO.

Surgical and social implications of extraction of mandibular third molars as a separate procedure before bilateral sagittal split osteotomy

In some units, lower wisdom teeth are extracted in a separate procedure before bilateral sagittal split osteotomy (BSSO), whereas in others they are removed at the time of the osteotomy. We identified 57 patients who had BSSO at Salisbury Hospital between October 2013 and September 2015, 40 of whom had their wisdom teeth extracted at the same time. The remaining 17 did not have wisdom teeth. Patients who have these teeth extracted as a separate procedure require at least one day off work, which can result in a loss of earnings. Our findings showed that the removal of third molars at the time of orthognathic surgery has considerable social and financial benefits, and does not increase the risk of morbidity.

CBCT location of the fusion between the buccal and lingual cortical in the mandibular ramus: importance to sagittal split osteotomy

Background

Mandibular Sagittal Split Osteotomy (MSSO) is a popular technique in orthognathic surgery used both to advance and to retreat the mandible. However, MSSO may incur in important complications, such as bad splits and sensorineural injuries. Knowing the location of the fusion between the buccal and lingual cortical (FBLC) in the mandibular ramus and the bone thickness in the region where osteotomies will be performed is determinant in MSSO planning to avoid complications. The aim of this study was to document and evaluate possible differences between sexes regarding the location of the FBLC in relation to the superior cortical of mandibular foramen (MF) and bone thickness in the region of interest for MSSO in a Brazilian population.

Material and Methods

Eighty five cone-beam Computed Tomography (CBCT) scans were used to perform linear measurements to determine the location of the FBLC. Bone thickness from the mandibular canal (MC) to the cortical external surfaces and the diameter of the MC were measured at three different points: mandibular ramus (A), mandibular angle (B) and mesial of the second molar (C).

Results

The FBLC was located at a mean distance of 8.3 mm from the superior cortical of the MF in males and 8.1 mm in females. There was no difference between males and females regarding the mean bone thickness from the MC to the buccal external surface at all the points investigated (p >>0.05). Bone thickness from the lingual external surface to the MC was bigger among females than males in regions B and C (p<0.05). The diameter of the MC was bigger among males in regions B and C.

Conclusions

Sexual dimorphism regarding mandibular bone thickness but not regarding the location of FBLC was present. This fundamental knowledge may assist to the panning of MSSO.

Key words:Cone-Beam Computed Tomography, mandibular nerve, orthognathic surgery, sagittal split ramus osteotomy.

An In Vitro Comparison Study of the Use of a Drill or a Saw in the Hunsuck-Dal Pont Modification of the Obwegeser Sagittal Split Osteotomy in Pig Mandibles

PURPOSE

Fracture lines in unfavorable locations are referred to as "bad splits" in a mandibular sagittal split osteotomy (SSO). Several modifications of the technique by Obwegeser have been introduced to minimize this risk. This in vitro study was performed to determine whether the shape of the osteotomy cut affects the torque and the fracture pattern of an SSO in pig mandibles.

MATERIALS AND METHODS

In a split-mouth model, 16 mandibles were split according to the Hunsuck-Dal Pont modification of the Obwegeser technique. Using an oscillating saw, sharp-edged osteotomies were created on one side of the mandible and round-edged osteotomies were created on the contralateral side using a Lindemann bur. Torque forces were measured during the splitting, and the lingual fracture pattern of each split was classified.

RESULTS

Torque forces were significantly (P < .05 by paired t test) decreased by 0.77 N-m (15.6%) when a saw was used for the osteotomy. In the 2 groups, fractures were produced along the mandibular canal. The mandible was more often completely fractured, including the lower mandibular border, when the fracture was created with an oscillating saw (P = .06 by Pearson χ² test). No correlation was found between the torque used and the fracture pattern.

CONCLUSION

Compared with round-edged osteotomies, sharp-edged osteotomies in pig mandibles facilitated the Hunsuck-Dal Pont modification of the Obwegeser sagittal splitting procedure and produced predictable results with decreased torque.

A morphometric analysis of the mandibular canal by cone beam computed tomography and its relevance to the sagittal split ramus osteotomy

PURPOSE

The aim of the present study was to morphometrically analyze the mandibular canal through the mandibular ramus by cone beam computed tomography (CBCT) and to relate the findings to performing sagittal split ramus osteotomy.

METHODS

CBCT of 200 patients were analyzed. Five parameters were measured at the axial scan, from the mandibular foramen to 21 mm below it (3-mm intervals). The canal was classified according to the position within the bone marrow space. Variations were evaluated according to age, sex, side, and number of mandibular teeth.

RESULTS/CONCLUSIONS

The following measurements increased gradually towards the most inferior level of measurement: the total thickness of the mandibular ramus through the center of the mandibular canal, the width of the bone marrow space (both buccal and lingual), and the narrowest width from the mandibular canal inner cortical to the mandibular ramus external cortical. The inner diameter of the mandibular canal slightly decreased to the same direction. Concerning the mandibular canal position within the bone marrow space, the percentage of the separate type increased towards the most inferior level of measurement, and the contact and fusion types decreased. Age, number of teeth, and sex had no significant influence on the total thickness of the mandibular ramus and on the narrowest width from the mandibular canal inner cortical to the mandibular ramus external cortical.

Does the Type of Maxillomandibular Deformity Influence Complication Rate in Orthognathic Surgery?

PURPOSE

Patients may encounter various complications during and after orthognathic surgery. The aim of this study was to compare the prevalence of complications in various skeletal deformities to see if an association exists.

MATERIALS AND METHODS

This retrospective cohort study assessed patients in 2 groups. Group 1 had class III skeletal deformity and group 2 had class II skeletal deformity with vertical maxillary excess (VME). Complications were studied in 2 stages: Stage 1 included perioperative and immediate (first 24 hours) postoperative complications namely difficult intubation, blood transfusion, bad splits, pain, and postoperative airway problems. Stage 2 included postoperative complications (from 24 hours up to 6 months after surgery namely bad splits and relapse). Age, sex, operation time, and the amount of jaw movements were considered as variables. Types of skeletal deformity were predictive factor of the study.

RESULTS

The authors studied 248 patients in 2 groups. In group 1, 13 (8.2%) patients needed blood transfusion during surgery up to 24 hours after operation and 27 (30%) patients in group 2. Analysis of data demonstrated a significant difference for blood transfusion between 2 groups (P = 0.001). In group 1, 8 (5.1%) patients had a difficult intubation compared with 13 (14.4%) patients in group 2.Comparison of mandibular movement and maximum mouth opening (MMO) did not show significant differences between 2 groups (P > 0.05). The amount of maxillary movement and horizontal discrepancy were different statistically in 2 groups (P < 0.05). Analysis of the data showed a significant difference in intubation between the 2 groups (P < 0.05). There were no differences between the 2 groups for bad splits, postoperative airway problems, or paresthesia (P > 0.05). Results did not demonstrate a significant difference for pain between the 2 groups (P > 0.05).

CONCLUSIONS

Patients with class II skeletal deformity and VME may have higher risk of perioperative blood loss and difficult intubation compared with patients with class III skeletal deformity.

Assessment of hematologic parameters before and after bimaxillary orthognathic surgery

PURPOSE

The purpose of the study was to evaluate changes of hematologic parameters in bimaxillary surgery.

METHODS

Fifty-three patients were prospectively evaluated and divided into groups based on the surgical procedure and sex (predictor variables). Hemoglobin, red blood cells, hematocrit, and platelet were the primary outcome variables, operation time the secondary outcome, and the patients' age and weight the other variables.

TRIAL REGISTRATION

NCT02364765 (U.S. National Institutes of Health, clinicaltrials.gov).

RESULTS

There was statistically significant difference between all hematologic parameters before and after surgery, for both men and women, and for all surgical groups. There was a positive correlation between operative time and the decrease (in %) of the hematologic parameters. Linear regression analysis suggested that the Hb values decrease 0.083 % for every minute increase in the operation time, and 0.066, 0.066, and 0.010 % for RBC, Hct, and platelet count, respectively. There was a negative correlation between weight and all hematologic parameters. Correlations between age and hematologic parameters were not statistically significant. Almost all correlations between age, weight, sex, and the surgery group and the hematologic parameters were considered as very weak. Only one patient was transfused.

CONCLUSIONS

It is suggested that operation time and patient's weight play a bigger role than patient's age and sex in the decrease of hematologic parameters after bimaxillary surgery.

Evidence-based outcomes following inferior alveolar and lingual nerve injury and repair: a systematic review

The inferior alveolar nerve (IAN) and lingual (LN) are susceptible to iatrogenic surgical damage. Systematically review recent clinical evidence regarding IAN/LN repair methods and to develop updated guidelines for managing injury. Recent publications on IAN/LN microsurgical repair from Medline, Embase and Cochrane Library databases were screened by title/abstract. Main texts were appraised for exclusion criteria: no treatment performed or results provided, poor/lacking procedural description, cohort <3 patients. Of 366 retrieved papers, 27 were suitable for final analysis. Treatment type for injured IANs/LNs depended on injury type, injury timing, neurosensory disturbances and intra-operative findings. Best functional nerve recovery occurred after direct apposition and suturing if nerve ending gaps were <10 mm; larger gaps required nerve grafting (sural/greater auricular nerve). Timing of microneurosurgical repair after injury remains debated. Most authors recommend surgery when neurosensory deficit shows no improvement 90 days post-diagnosis. Nerve transection diagnosed intra-operatively should be repaired in situ; minor nerve injury repair can be delayed. No consensus exists regarding optimal methods and timing for IAN/LN repair. We suggest a schematic guideline for treating IAN/LN injury, based on the most current evidence. We acknowledge that additional RCTs are required to provide definitive confirmation of optimal treatment approaches.

Fixation of mandibular angle fractures: clinical studies

PURPOSE

The purpose of this study was to review the literature regarding the evolution of current thoughts on fixation of mandibular angle fractures (MAFs).

METHODS

An electronic search in PubMed was undertaken in August 2012. The titles and abstracts from these results were read to identify studies within the selection criteria. Eligibility criteria included studies from the last 30 years (from 1983 onwards) reporting clinical studies of MAFs.

RESULTS

The search strategy initially identified 767 studies. The references from 1983 onwards totaled 727 articles. Fifty-four studies were identified without repetition within the selection criteria. Two articles showing significance in the development of treatment techniques were included. Additional hand-searching yielded 13 additional papers. Thus, a total of 69 studies were included.

CONCLUSIONS

Prospective randomized controlled studies of MAFs repair techniques are scarce. The available data at best predict that complications are associated with all kinds of fixation techniques. The similar results of complications in studies using different methods of fixation indicate that biomechanics are only one factor to be considered when treating MAFs. A second fracture in the mandible (which was observed in the majority of the studies' population) can confound the outcome data because the fixation requirements of a double fracture are often different from those for an isolated fracture. It can be necessary additional effort intended for increase of stability when using biodegradable plate system to fixate MAFs. The use of 1.3 mm malleable miniplates was associated with an unacceptable incidence of plate fracture, suggesting that this is not the most adequate system to treat MAFs. The use of the 3D grid plates has shown good clinical results. The efficiency of locking miniplate system is yet to be proven because there are few clinical studies with its use to fixate MAFs, although they have shown good results. When considering the use of semirigid or rigid fixation systems, the use of two miniplates outweigh the advantages of the use of one reconstruction plate, although the use of miniplates is not recommended for displaced comminuted MAFs. Although it has been shown that absolute rigid fixation is not necessary for fracture healing, any system that provides superior stability without impacting negatively on other aspects of the procedure, i.e., time, exposure, and cost, should be favored. MAFs can be treated in a highly effective way and with a relatively low rate of complications with monocortical miniplate fixation. The large number of studies on the treatment of MAF reflects the fact that a consensus has not been reached for a single, ideal treatment method.

Teeth in the line of mandibular fractures

PURPOSE

This study aims to review the literature regarding the evolution of current thoughts on the management of teeth in the line of mandibular fractures (MFs).

METHODS

An electronic search in PubMed was undertaken in June 2012. The titles and abstracts from these results were read to identify studies within the selection criteria-studies reporting clinical series of MFs in which the management of teeth in the fracture line was analyzed.

RESULTS

The search strategy initially yielded 731 references. Twenty-seven studies were identified without repetition within the selection criteria. Additional hand searching yielded 12 additional papers.

CONCLUSIONS

It is suggested that rigid fixation systems and the use of antimicrobial agents have reduced the incidence of infection in cases of teeth in the line of MFs. Tooth buds in the line of MFs should not be removed or replaced in the (alleged) proper position despite the degree of displacement, since studies showed that even tooth buds in the early stage of calcification and those involved in widely displaced fracture sites continued development and erupted. Its removal should be considered in cases of infection, which is a predictive factor of abnormality and/or impaction. Intact teeth in the fracture line should be left in situ if they show no evidence of severe loosening or inflammatory change. Permanent teeth maintained in the line of fracture should be followed up clinically and radiographically for at least 1 year to ensure that any unnecessary endodontic treatment is avoided. Teeth in the line of fracture that prevents reduction of fractures, teeth with fractured roots, a partially impacted wisdom tooth with pericoronitis, and a tooth with extensive periapical lesion should be removed. Teeth in the line of MFs should also be removed when located in sites where there is extensive periodontal damage, with broken alveolar walls, resulting in the formation of a deep pocket (making optimal healing doubtful).

Three-dimensional evaluation of lingual split line after bilateral sagittal split osteotomy in asymmetric prognathism

OBJECTIVES

The aim of this study was to evaluate the pattern of lingual split line when performing a bilateral sagittal split osteotomy (BSSO) for asymmetric prognathism. This was accomplished with the use of cone-beam computed tomography (CBCT) and three-dimensional (3D) software program.

MATERIALS AND METHODS

The study group was comprised of 40 patients (20 males and 20 females) with asymmetric prognathism, who underwent BSSO (80 splits; n=80) from January 2012 through June 2013. We observed the pattern of lingual split line using CBCT data and image analysis program. The deviated side was compared to the contralateral side in each patient. To analyze the contributing factors to the split pattern, we observed the position of the lateral cortical bone cut end and measured the thickness of the ramus that surrounds the mandibular lingula.

RESULTS

The lingual split patterns were classified into. The true "Hunsuck" line was 60.00% (n=48), and the bad split was 7.50% (n=6). Ramal thickness surrounding the lingual was 5.55±1.07 mm (deviated) and 5.66±1.34 mm (contralateral) (P=0.409). The position of the lateral cortical bone cut end was classified into three types: A, lingual; B, inferior; C, buccal. Type A comprised 66.25% (n=53), Type B comprised 22.50% (n=18), and Type C comprised 11.25% (n=9).

CONCLUSION

In asymmetric prognathism patients, there were no differences in the ramal thickness between the deviated side and the contralateral side. Furthermore, no differences were found in the lingual split pattern. The lingual split pattern correlated with the position of the lateral cortical bone cut end. In addition, the 3D-CT reformation was a useful tool for evaluating the surgical results of BSSO of the mandible.

Effect of perioperative buccal fracture of the proximal segment on postoperative stability after sagittal split ramus osteotomy

Objectives

Buccal fracture of the mandibular proximal bone segment during bilateral sagittal split ramus osteotomy (SSRO) reduces the postoperative stability. The primary aim of this study is to evaluate the effect of this type of fracture on bone healing and postoperative stability after mandibular setback surgery.

Materials and Methods

Ten patients who experienced buccal fracture during SSRO for mandibular setback movement were evaluated. We measured the amount of bone generation on a computed tomography scan, using an image analysis program, and compared the buccal fracture side to the opposite side in each patient. To investigate the effect on postoperative stability, we measured the postoperative relapse in lateral cephalograms, immediately following and six months after the surgery. The control group consisted of ten randomly-selected patients having a similar amount of set-back without buccal fracture.

Results

Less bone generation was observed on the buccal fracture side compared with the opposite side (P<0.05). However, there was no significant difference in anterior-posterior postoperative relapse between the group with buccal fracture and the control group. The increased mandibular plane angle and anterior facial height after the surgery in the group with buccal fracture manifested as a postoperative clockwise rotation of the mandible.

Conclusion

Bone generation was delayed compared to the opposite side. However, postoperative stability in the anterior-posterior direction could be maintained with rigid fixation.

Influence of osteotomy procedure and surgical experience on early complications after orthognathic surgery in the mandible

INTRODUCTION

This study evaluated the influence of osteotomy procedure and surgical experience on early complication rates following orthognathic surgery in the mandible.

MATERIALS AND METHODS

In a retrospective study, patients who underwent a mandibular osteotomy (Obwegeser-Dal Pont (ODP) and Hunsuk-Epker (HE)) were included. Incidence of "bad splits", "bleeding episodes", "delayed wound healing", "failed osteosynthesis" and "nerve lesions" at 2 months post-operatively were recorded. Surgical experience was classified as: beginner (<10), intermediate (10-40) and expert (>40). Complications were correlated to the surgical approach and the experience level of the surgeon.

RESULTS

400 patients were included. 200 underwent a bimaxillary approach. 186 patients were operated using the ODP technique, 214 according to HE. Multivariate analysis confirmed significantly more unwanted fractures and bleeding events for ODP when compared to HE (p = 0.28, p = 0.003). Experienced surgeons had more osteosynthesis failures (0.047) and significantly more nerve lesions than the other groups (p = 0.01).

DISCUSSION

The HE osteotomy showed a more reliable fracture mechanism with less relevant bleeding episodes. Differences between the surgeons of varying training status were marginal with exception of a higher rate of osteosynthesis failure and temporary hypoesthesia in the experienced group.

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.

Morphologic features of the mandibular ramus associated with increased surgical time and blood loss in sagittal split-ramus osteotomy

PURPOSE

To determine whether specific morphologic features of the mandibular ramus can predict increased surgical time and blood loss in sagittal split-ramus osteotomy (SSRO).

MATERIALS AND METHODS

The clinical and morphologic features of the mandibular ramus, obtained from computed tomographic images (n=50), were analyzed to predict the surgical time, the time required for ablation of the medial mandibular ramus, and the time required for sectioning of the mandible in performing a modified Obwegeser SSRO.

RESULTS

Significant factors associated with surgical time were an anterior border of the ramus at least 10.5 mm wide, a maximal length of the thickened ramus of at least 8.5 mm, and a distance from the mandibular incisor to the posterior border of the mandible of at least 97.5 mm. There were significant differences in blood loss between the 2 axial aspects of the medial ramus.

CONCLUSIONS

The greater protrusion of the medial oblique ridge, thickened ramus, and longer distance from the mandibular incisors to the posterior border of the mandible may increase the surgical time and blood loss in patients undergoing classic SSRO. When planning or performing an SSRO, the morphologic features obtained from computed tomographic images may help surgeons gain a better understanding of the potential difficulties when the surgical site involves the medial aspect of the ascending ramus of the mandible.