Jop P. Verweij

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

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

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

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

Angled Osteotomy Design Aimed to Influence the Lingual Fracture Line in Bilateral Sagittal Split Osteotomy: A Human Cadaveric Study

PURPOSE The traditional osteotomy design in the bilateral sagittal split osteotomy includes a horizontal lingual bone cut, a connecting sagittal bone cut, and a vertical buccal bone cut perpendicular to the inferior mandibular cortex. The buccal bone cut extends as an inferior border cut into the lingual cortex. This study investigated a modified osteotomy design including an angled oblique buccal bone cut that extended as a posteriorly aimed inferior border cut near the masseteric tuberosity. MATERIALS AND METHODS The authors implemented a randomized controlled study. The study sample was comprised of 28 cadaveric dentulous mandibles. The primary outcome variable was the pattern of lingual fracture induced using the conventional (n = 14) and modified (n = 14) osteotomy designs. The secondary outcome variables included the incidence of bad splits and the status of the inferior alveolar nerve (IAN). Descriptive and bivariate statistics were computed. RESULTS The angled osteotomy design resulted in a significantly larger number of the lingual fractures originating from the inferior border cut (odds ratio [OR] = 1.54; 95% confidence interval [CI], 1.27-1.86; P < .01), with a significantly more posterior relation of the fracture line to the mandibular canal (OR = 2.11; 95% CI, 1.22-3.63; P < .01) and foramen (OR = 1.99; 95% CI, 1.28-3.08; P < .01). No bad splits occurred with the angled design, whereas 3 bad splits occurred with the conventional design, although this difference was not statistically significant (OR = 1.11; 95% CI, 0.99-1.25; P = .07). IAN status was comparable between designs, although the nerve more frequently required manipulation from the proximal mandibular segment when the conventional design was used (OR = 1.21; 95% CI, 0.99-1.47; P = .06). CONCLUSION The results suggest that the angled osteotomy design promotes a more posterior lingual fracture originating from the inferior border cut and a trend was apparent that this also might decrease the incidence of bad splits and IAN entrapment. These results must be carefully extrapolated to the clinical setting, with future studies clarifying these findings.

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

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

Bilateral sagittal split osteotomy in a mandible previously reconstructed with a non-vascularized bone graft

We report a bilateral sagittal split osteotomy (BSSO) in a reconstructed mandible. A 28-year-old woman underwent a segmental mandibulectomy due to a multicystic ameloblastoma in the left jaw. After primary plate reconstruction, final reconstruction was performed with a left posterior iliac crest cortico-cancellous autograft. Due to a pre-existing Class II malocclusion, the patient was analyzed for combined orthodontic-surgical treatment. Subsequently, after 1 year of orthodontic treatment, the BSSO was planned. The sagittal split was performed in the remaining right mandible and on the left side in the iliac crest cortico-cancellous autograft. Ten months later, oral rehabilitation was completed with implant placement in the neomandible. Follow-up showed a Class I occlusion, with good function. The patient was very satisfied with the functional and aesthetic results. This case shows that a BSSO can be performed in a reconstructed mandible, without side effects and with good functional and aesthetic results.

Autotransplantation of teeth using computer-aided rapid prototyping of a three-dimensional replica of the donor tooth: a systematic literature review

This systematic review provides an overview of studies on autotransplantation techniques using rapid prototyping for preoperative fabrication of donor tooth replicas for preparation of the neo-alveolus. Different three-dimensional autotransplantation techniques and their treatment outcomes are discussed. The systematic literature search yielded 19 articles that satisfied the criteria for inclusion. These papers described one case-control study, four clinical observational studies, one study with a clinical and in vitro part, four in vitro studies, and nine case reports. The in vitro studies reported high accuracy for the printing and planning processes. The case reports all reported successful transplantation without any pathological signs. The clinical studies reported a short extraoral time of the donor tooth, with subsequent success and survival rates of 80.0-91.1% and 95.5-100%, respectively. The case-control study reported a significant decrease in extraoral time and high success rates with the use of donor tooth replicas. In conclusion, the use of a preoperatively designed surgical guide for autotransplantation enables accurate positional planning, increases the ease of surgery, and decreases the extraoral time. However, the quality of the existing body of evidence is low. Further research is therefore required to investigate the clinical advantages of this innovative autotransplantation technique.

Success and survival of autotransplanted premolars and molars during short-term clinical follow-up.

AIM Autotransplantation is an elegant therapy for single tooth replacement that is too often overlooked in patients with missing teeth. Especially, autotransplantation of third molars to replace heavily damaged or missing molars is often not considered. This study investigated the success and survival of autotransplanted premolars and molars during clinical follow-up. MATERIALS AND METHODS The medical files and radiographs of 97 consecutive patients were retrospectively investigated. Seventy-nine patients could be included in this study. Autotransplantation of 97 premolars and 14 molars (111 procedures) was performed. The median follow-up time was equal to 13.4 months. RESULTS In this study group, 82.0% of transplanted teeth were classified as successful and 98.2% were present at the end of follow-up. No transplants were extracted during standard follow-up of 1 year. The 5-year tooth survival probability was 87.5% (95%CI 64.5-100). One premolar and one molar were extracted, respectively, 4 and 9 years after autotransplantation. CONCLUSIONS These results show that autotransplantation is associated with high success and survival rates and can provide a reliable treatment option for tooth replacement in young patients. Further research regarding long-term outcome is necessary to assess if the transplanted teeth function as normal teeth after clinical follow-up.

Incidence and recovery of neurosensory disturbances after bilateral sagittal split osteotomy in different age groups: a retrospective study of 263 patients

This study aimed to investigate the incidence of neurosensory disturbance (NSD) after bilateral sagittal split osteotomy (BSSO) in different age groups and to assess the probability of sensory recovery in patients aged <19 years, 19-30 years, and >30 years. Hypoaesthesia of the lower lip was assessed subjectively and objectively immediately after BSSO and at 1 week and 1, 6, and 12 months after BSSO. Hypoaesthesia was considered permanent if it was present 1 year after BSSO. The frequency of NSD immediately after surgery was significantly higher in older patients. The cumulative incidence of recovery at 1 year was lower and the mean time to recovery was longer in the older patients, although these differences were not statistically significant. Older age was a significant risk factor for permanent hypoaesthesia, with an incidence of 4.8% per patient aged <19 years, 7.9% per patient aged 19-30 years, and 15.2% per patient aged >30 years. These findings show that the risk of NSD after BSSO is significantly higher in older patients. These results may aid surgeons in preoperative patient counselling and in deciding the optimal age at which to perform BSSO.

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.

Influence of inferior border cut on lingual fracture pattern during bilateral sagittal split osteotomy with splitter and separators: A prospective observational study

Bilateral sagittal split osteotomy (BSSO) is a widely used orthognathic surgery technique. This prospective observational study investigated the correspondence between the planned inferior border cut and the actually executed inferior border cut during BSSO. The influence of the inferior border cut on lingual fracture patterns was also analyzed. Postoperative cone beam computed tomography (CBCT) scans of 41 patients, representing 82 sagittal split osteotomies, were investigated. The inferior border cut was intended to penetrate completely through the caudal cortex. Descriptive statistics were used to analyze the executed inferior border cuts. Mixed models were used to investigate the influence of independent variables such as the surgeons experience on the inferior border cut. Secondarily the influence of the inferior border cut on lingual fracture patterns and the incidence of bad splits was assessed. The inferior border cut reached the caudal cortex in all cases, but reached the lingual cortex in only 38% of the splits. There was no significant relationship between the inferior border cut and a specific lingual fracture line. In this study, postoperative CBCT analysis revealed that the bone cuts during BSSO were often not placed exactly as planned. No significant relationship between the inferior border cut and lingual fracture patterns or bad splits was, however, detected.