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The purpose of this study was to elucidate the effects of mandibular anatomy and osteotomy technique on lingual fracture patterns in SSRO. The predictor variables were: length of horizontal medial osteotomy; type of border osteotomy; buccolingual width; and vertical length of the basal cortex. The outcome variable was the type of lingual split pattern. This was categorized into four types according to a lingual split scale (LSS): LSS 1, true Hunsuck; LSS 2, fracture line to posterior border of the ramus; LSS 3, through to mandibular canal; LSS 4, unfavorable fracture pattern. Data were analyzed using analysis of variance and the Pearson χ2 test. Values of p < 0.05 were considered statistically significant. The study sample comprised 312 lingual split patterns in 156 patients. The most common type of lingual split pattern was LSS 1 (n = 204). There was a significant relationship between inferior border osteotomy type and LSS type (p = 0.001). Whilst LSS 1 was the most common among all border osteotomy types. LSS 4 was most frequently observed in cases where the lower border osteotomy remained in the buccal surface. According to the results of this study, the likelihood of an unfavorable split pattern increases when the lower border osteotomy remains in the buccal surface. [ABSTRACT FROM AUTHOR]

Abstract 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

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. [ABSTRACT FROM AUTHOR]

This study aims to analyse the relationship between the incidence of bad splits and the surgical tools adopteded to perform bilateral sagittal split ramus osteotomy (BSSRO).BSSROs performed by the same experienced surgeon period were reviewed, retrospectively. The patients were divided into three groups according to the surgical instrument used to perform the osteotomy: a Lindemann burr, reciprocating saw or piezosurgery. Among the 1120 BSSROs performed, 5 bad fractures were detected during the observation period: 3 among patients operated with the Lindemann burr (0.8%) and 2 among those operated with a reciprocating saw (0.5%). There was no significant correlation between the bad split rate and age and gender of the patients, the type of malocclusion or the type of instrument used to perform the osteotomy. Within the limitations of the study it seems that the the choice of the osteotomy tool for BSSRO does not influence the rate of bad fractures and, therefore, the selection of the osteotmy tool should be left to the discretion of the surgeon. [ABSTRACT FROM AUTHOR]

Background/Purpose: The neurosensory disturbance is a common complication following sagittal split ramus osteotomy (SSRO) whereas the shortest buccal bone marrow (SBM) is an important risk factor. The present study aimed to investigate the relationship between the occurrence rates of SBM among three skeletal patterns. Methods: The cone-beam computed tomography (CBCT) images of 90 participants were divided into skeletal Class I, II, and III. There were six horizontal planes separated apart by a 2 mm interval; it started with plane 0 (original intact mandibular canal) to plane 5 which was 10 mm below. The data of SBM were divided into two groups (SBM ≥ 1 mm and SBM

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background/purpose: The neurosensory disturbance is a common complication following sagittal split ramus osteotomy (SSRO) whereas the shortest buccal bone marrow (SBM) is an important risk factor. The present study aimed to investigate the relationship between the occurrence rates of SBM among three skeletal patterns.Methods: The cone-beam computed tomography (CBCT) images of 90 participants were divided into skeletal Class I, II, and III. There were six horizontal planes separated apart by a 2 mm interval; it started with plane 0 (original intact mandibular canal) to plane 5 which was 10 mm below. The data of SBM were divided into two groups (SBM ≥ 1 mm and SBM < 1 mm). With an SBM value < 1 mm, we defined a high occurrence rate of postoperative neurosensory abnormality or unfavorable split.Results: The Class III patients had the smallest SBM value (1.31-1.75 mm) whereas the Class II patients had the largest SBM value (1.57-2.09 mm). For the Class III patients, the highest and lowest occurrence rates of SBM were 56.5% and 43.5% respectively. For the Class II patients, the highest and lowest occurrence rates of SBM were 37.1% and 17.7% respectively. The patients with Class III malocclusion had higher occurrence rates of SBM than the patients with Class II malocclusion.Conclusion: Class III had a significantly higher occurrence of probability (SBM < 1 mm) than Class II. Therefore, patients with Class III were more likely to experience postoperative neurosensory abnormalities and unfavorable split than patients with Class II. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the prevalence of a ‘bad’ split after sagittal ramus osteotomies (SRO) and report the results of initial mandibular healing. A retrospective cohort study derived from patients treated by a single surgeon at one institution between 2004 and 2013 was performed. An index group consisting of a series of subjects with a spectrum of bimaxillary dentofacial deformities also involving the chin and symptomatic chronic obstructive nasal breathing was identified. The SRO design, bicortical screw fixation technique, and perioperative management were consistent. Outcome variables included the occurrence of a ‘bad’ split and the success of initial SRO healing. Two hundred sixty-two subjects undergoing 524 SROs met the inclusion criteria. Their average age was 25 years (range 13–63 years) and 134 were female (51%). Simultaneous removal of a third molar was performed during 209 of the SROs (40%). There were no ‘bad’ splits. All subjects achieved successful bone union, the planned occlusion, and return to a chewing diet and physical activities by 5 weeks after surgery. The presence of a third molar removed during SRO was not associated with an increased frequency of a ‘bad’ split or delayed mandibular healing. [ABSTRACT FROM AUTHOR]

The most common complications that are associated with bilateral sagittal split osteotomy are: bad splits, postoperative infection, removal of osteosynthesis material, and neurosensory disturbances of the lower lip. Particularly in elective orthognathic surgery, it is important that surgeons inform their patients about the risk of these complications and attempt to minimize these risks. The purpose of this literature review and meta-analysis is to provide an overview of these common complications and their risk factors. After a systematic electronic database search, 59 studies were identified and included in this review. For each complication, a pooled mean incidence was computed. Both the pooled study group and the pooled ‘complication group’ were analysed. The mean incidences for bad split (2.3% per SSO), postoperative infection (9.6% per patient), removal of the osteosynthesis material (11.2% per patient), and neurosensory disturbances of the lower lip (33.9% per patient) are reported. Regularly reported risk factors for complications were the patient's age, smoking habits, presence of third molars, the surgical technique and type of osteosynthesis material. This information may help the surgeon to minimize the risk of these complications and inform the patient about the risks of complications associated with bilateral sagittal split osteotomy. [ABSTRACT FROM AUTHOR]

An unfavourable and unanticipated pattern of the bilateral sagittal split osteotomy (BSSO) is generally referred to as a ‘bad split’. Patient factors predictive of a bad split reported in the literature are controversial. Suggested risk factors are reviewed in this article. A systematic review was undertaken, yielding a total of 30 studies published between 1971 and 2015 reporting the incidence of bad split and patient age, and/or surgical technique employed, and/or the presence of third molars. These included 22 retrospective cohort studies, six prospective cohort studies, one matched-pair analysis, and one case series. Spearman's rank correlation showed a statistically significant but weak correlation between increasing average age and increasing occurrence of bad splits in 18 studies ( ρ = 0.229; P < 0.01). No comparative studies were found that assessed the incidence of bad split among the different splitting techniques. A meta-analysis pooling the effect sizes of seven cohort studies showed no significant difference in the incidence of bad split between cohorts of patients with third molars present and concomitantly removed during surgery, and patients in whom third molars were removed at least 6 months preoperatively (odds ratio 1.16, 95% confidence interval 0.73–1.85, Z = 0.64, P = 0.52). In summary, there is no robust evidence to date to show that any risk factor influences the incidence of bad split. [ABSTRACT FROM AUTHOR]

An unfavourable and unanticipated pattern of the mandibular sagittal split osteotomy is generally referred to as a ‘bad split’. Few restorative techniques to manage the situation have been described. In this article, a classification of reported bad split pattern types is proposed and appropriate salvage procedures to manage the different types of undesired fracture are presented. A systematic review was undertaken, yielding a total of 33 studies published between 1971 and 2015. These reported a total of 458 cases of bad splits among 19,527 sagittal ramus osteotomies in 10,271 patients. The total reported incidence of bad split was 2.3% of sagittal splits. The most frequently encountered were buccal plate fractures of the proximal segment (types 1A–F) and lingual fractures of the distal segment (types 2A and 2B). Coronoid fractures (type 3) and condylar neck fractures (type 4) have seldom been reported. The various types of bad split may require different salvage approaches. [ABSTRACT FROM AUTHOR]

Abstract If during a sagittal split osteotomy a buccal plate fracture occurs, it inevitably results in a time-consuming procedure with, in many cases, hypoesthesia of the mental region as a consequence of manipulation of the inferior alveolar nerve. We would like to present a novel technique to solve a (threatening) buccal plate fracture that is quick and easy to perform, and has thus far not resulted in hypoesthesia. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the lingual fracture patterns after sagittal split osteotomy (SSO) using short and long medial osteotomy cuts, via three-dimensional (3D) cone beam computed tomography (CBCT). Forty-six subjects participated in this prospective study. Two types of medial osteotomy line were made: for type I, the medial osteotomy line was finished just before the lingula; for type II, the medial osteotomy line was extended 3–4 mm beyond the lingula. Three fracture patterns were observed after SSOs. There were no significant differences in the medial fracture patterns between the two medial osteotomy types ( P = 0.16). The buccolingual thickness of the ramus was lower in fractures with pattern 3 (bad split) than in the two other fracture patterns. The length of the medial osteotomy line – short or long – did not alter the prevalence of a bad split. The bone thickness of the ramus may affect the type of fracture pattern on the medial side of the ramus. [ABSTRACT FROM AUTHOR]

Background: The timing of removal of mandibular third molars (M3) in Sagittal Split Osteotomy (SSO) has been an issue of contention. The aim of this retrospective study is to identify the incidence of unfavorable fractures during SSO with the presence of M3 and to identify the association between unfavorable fractures with the factors specifically related to the M3. Materials and Methods: Retrospective analysis of consecutive bilateral sagittal split osteotomy (BSSO) patient's treatment records of 208 patients treated by a single surgeon was analyzed. The position of M3, fracture details, and demographics were collected. Descriptive statistics and Chi-square tests were employed in SPSS package. A P ≤ 0.05 was taken as significant. Results: There were altogether 416 SSO performed. M3 was completely impacted in 88.9% of all instances, and in 85.6% of the instances, the bulk of the M3 was identified to be above the external oblique ridge. In 59.4% of the cases, M3 was positioned in alignment with the arch as observed during surgery. There were about 27 (6.5%) instances of unfavorable splits. A statistically significant relationship was observed with M3 root morphology and axial position of M3. Discussion: This study for the first time has confirmed the spatial positioning of M3 as one of the several causes of unfavorable splits during SSO. An impacted M3 that lies below the oblique ridge, distoangularly/vertically oriented, with divergent/supernumerary root would cause unfavorable splits when the spreader is not used properly. Potential causes and influencing factors of the unfavorable splits are discussed. [ABSTRACT FROM AUTHOR]

Purpose: One of the operative complications of the sagittal split osteotomy of the mandible is a bad split, which describes an unfavorable or irregular fracture of the mandible in the course of the osteotomy. The purpose of this study is to identify previous studies which reported incidences of bad split occurrence during sagittal split osteotomy and to discuss its mechanisms and risk factors, based on a literature review, in order to minimize their occurrence. A few illustrative cases are also presented. Methods: An electronic search was undertaken in January 2011. The titles and abstracts from these results ( n = 363) were read for identifying studies which reported incidences of bad split occurrence during sagittal split osteotomy procedures. Results: Twenty-one studies were identified and assessed. The incidence of bad splits from these studies varied between 0.21% and 22.72%. The buccal plate of the proximal segment and the posterior aspect of the distal segment were the most affected areas. Discussion: The surgical patient should be evaluated according to age and the presence of unerupted/impacted third molars. Prevention is focused on adequate osteotomy design, eliminating sharp angle where abnormal stress occurs on bony segments, completion of adequate cuts into the retrolingular depression and through the inferior border, and careful separation of the segments. The SSO is an extremely technical and sensitive procedure, and careful attention will probably prevent most unfavorable splits. If a fracture occurs, the fractured segments should be incorporated into the fixation scheme if possible. The occurrence of bad splits cannot always be avoided. When adequately treated the chances of functional success are good. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study investigated a new technique for the bilateral sagittal split osteotomy (BSSO) by adding a new osteotomy line at the inferior border of the mandible in the Obwegeser–Dal Pont operation. Material and methods: For this purpose a test system was designed and 100 pig mandibles were split to assess the test’s reliability, to compare the torque necessary to split the mandible in both techniques and to record the fracture lines. The splitting technique was standardized, avoiding any contact with the inferior alveolar nerve. All outcomes were statistically examined by paired t-tests. Results: By using the new technique, we demonstrated a decrease in the torque force required to split the mandible of 29.7% (t(69)=−12.68; p <0.05, paired t-test) compared to the Obwegeser–Dal Pont technique. The fracture lines were close to ideal. Conclusion: The additional osteotomy facilitates the BSSO technique and it reduces the likelihood of bad splits and damage to the inferior alveolar nerve in pig mandibles. [Copyright &y& Elsevier]

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., Competing Interests: The authors have no conflicts of interest to disclose.

Abstract: One of the operative complications during sagittal split osteotomy (SSO) in orthognatic surgery is a bad split, meaning an undesired fracture of the mandible during osteotomy. The aim of this study was to find out if there is a relation between the occurrence of bad splits during SSO and the presence of third molars, the patient''s age, or the surgeon''s experience. Clinical notes of 110 consecutive patients who had had a total of 220 SSOs using the Obwegeser/Dal Pont technique were evaluated and divided into three groups: 1 missing third molar (n =168); 2 retained or impacted third molar that was removed during the SSO (n =23); and 3 third molar left in place during SSO (n =29). There were a total of 12 (6%) bad splits. 9 (5%) in group 1, two (9%) in group 2, and one (3%) in group 3. There were no significant differences between groups 1–3, in particular the surgeon''s qualification had no influence on the incidence. Older patients seemed more at risk of a bad split than younger ones. [Copyright &y& Elsevier]

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.