Maxillomandibular advancement in edentulous patients as a treatment option for obstructive sleep apnea: report of two cases and a proposed treatment protocol.

Obstructive sleep apnea (OSA) is a common disease that often causes debilitating symptoms. In its most severe form, OSA increases the risk of cardiovascular disease and mortality. OSA is characterized by repeated episodes of pharyngeal collapse leading to airway obstruction. The treatment options available in severe cases are limited to continuous positive airway pressure ventilation and maxillomandibular advancement (MMA). OSA is particularly difficult to treat successfully in edentulous patients. Two cases are presented here to illustrate use of MMA in edentulous patients with OSA. Our learning points based on these cases are shared, and a treatment and follow-up protocol is proposed for this specific patient group.

A prospective study of soft- and hard-tissue changes after mandibular advancement surgery: Midline changes in the chin area.

INTRODUCTION: The purpose of this research was to prospectively determine the ratio of 2 soft-tissue landmarks, pogonion (sPg) and menton (sMe), to their hard-tissue counterparts (Pg and Me) in the sagittal and vertical directions for mandibular lengthening surgeries. METHODS: We drew a sample from the prospective Orthognathic and Orthofacial Surgery Research study, consisting of patients who underwent surgical mandibular lengthening (alone or in combination with maxillary osteotomy) without genioplasty. We digitized landmarks using Facewizz software and determined the relationships between the hard- and soft-tissue changes by correlation analysis. RESULTS: Pearson correlation test showed a significant correlation between the type of surgery and the sPg:Pg and sMe:Me ratios. The sPg:Pg ratio was 87% for mandibular lengthening only and 102% for mandibular lengthening in combination with maxillary surgery. The sMe:Me ratio was 85% and 96% for upward and downward movements, respectively. CONCLUSIONS: The average ratios presented in this study for the pogonion and menton can aid in preoperative planning by providing estimates for soft-tissue behavior. Further stratifications will be possible after the Orthognathic and Orthofacial Surgery Research database is enriched with more inclusions.

Autotransplantation With a 3-Dimensionally Printed Replica of the Donor Tooth Minimizes Extra-Alveolar Time and Intraoperative Fitting Attempts: A Multicenter Prospective Study of 100 Transplanted Teeth.

PURPOSE: Three-dimensional (3D) autotransplantation is a technique for surgical transposition of a tooth to another site within one patient, using 3D printed replicas of the donor tooth. In this study, we evaluated intraoperative experiences during 3D autotransplantation of teeth. MATERIALS AND METHODS: A multicenter prospective clinical study was implemented. All procedures were performed using preoperative cone-beam computed tomography imaging and computer-assisted design with computer-assisted manufacturing resulting in a 3D replica of the donor tooth. RESULTS: The 100 autotransplantation procedures (79 patients) included canines, premolars, molars, and 1 supernumerary tooth. In 82% of the procedures, the transplantation was performed with an extra-alveolar time of less than 1 minute and an immediate good fit of the donor tooth. In 14%, the extra-alveolar time was 1 to 3 minutes or multiple fitting attempts were necessary. In 4%, the extra-alveolar time exceeded 3 minutes. Difficulties during the procedures were caused by movement artifacts on the preoperative cone-beam computed tomography imaging, a long interval between the imaging and the procedure, or insufficient bone volume at the recipient site. CONCLUSIONS: The use of a 3D printed donor tooth replica during autotransplantation procedures minimized the extra-alveolar time and intraoperative fitting attempts of transplants. This facilitated a quick and reliable treatment and enabled more difficult procedures.

Root Elongation After Autotransplantation in 58 Transplanted Premolars: The Radiographic Width of the Apex as a Predictor.

PURPOSE: Autotransplantation of premolars with incomplete root development is a reliable treatment option for tooth replacement. Nevertheless, little is known about root development after transplantation of teeth. The aim of this study was to evaluate preoperative root development stage and radiographic width of the apex as predictors for root elongation after autotransplantation. MATERIALS AND METHODS: A retrospective cohort study was implemented and composed of patients who underwent autotransplantation of at least 1 premolar. Using panoramic radiographs (orthopantomograms), calibrated measurements were taken to record the root development stage of the donor tooth, width of the apex, and root length of the transplanted tooth. RESULTS: Forty-five patients (58 transplants) were included. Mean follow-up time was 12 months (range, 4 to 26 months). Fifty-three transplanted teeth (91.4%) showed root elongation. Mean root elongation at end of follow-up was 1.9 mm (range, 0.0 to 4.3 mm). A wide-open apex before transplantation was significantly associated with root elongation after autotransplantation (P < .01). Root development stage (P = .82) did not show significant associations with root elongation. CONCLUSIONS: A wide-open apex (>2.0 mm) is an important predictor of root elongation after autotransplantation of premolars. This might be a better predictor for root development than preoperative root development stage.

Finding the Ledge: Sagittal Analysis of Bony Landmarks of the Orbit.

PURPOSE: This study determined the average distances and angles between anatomic landmarks within the orbit, with an emphasis on localization of the orbital process of the palatine bone. This information will help the surgeon with treatment planning and surgical procedures. PATIENTS AND METHODS: Four anatomic landmarks were identified retrospectively on computed tomograms of 100 adult Caucasian patients (50 men and 50 women): the top of the infraorbital margin superior to the infraorbital foramen (point A), the top of the orbital process of the palatine bone (point B), the anteriormost bony portion of the superior orbital fissure (point C), and the ventrolateral aspect of the bony entrance of the optic canal (point D). The distances between these points were measured, as were the angle between the medial wall of the orbit and a line connecting points A to D at the level of the optic nerve. RESULTS: The mean distances between the orbital rim (point A) and the orbital process of the palatine bone (point B) were 33.8 mm in men and 32.7 mm in women. Men had markedly larger bony orbits than women; however, women had a larger angle than men for the 2 orbits. CONCLUSION: Obtaining these measurements preoperatively can enable a safer and more predictable surgical approach to the orbit, which can help lower the risk of damaging important neighboring structures. A preformed reconstruction plate can be manufactured or a standard reconstruction plate can be customized according to these measurements; during reconstruction, they also can help adequately localize the posterior ledge, specifically the orbital process of the palatine bone. These 2 aspects could ensure a more precise reconstruction of the orbital floor.

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 surgeon's 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.

Risk factors for common complications associated with bilateral sagittal split osteotomy: A literature review and meta-analysis.

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.

Autotransplantation of Premolars With a 3-Dimensional Printed Titanium Replica of the Donor Tooth Functioning as a Surgical Guide: Proof of Concept.

PURPOSE: Autotransplantation of premolars is a good treatment option for young patients who have missing teeth. This study evaluated the use of a preoperatively 3-dimensional (3D)-printed replica of the donor tooth that functions as a surgical guide during autotransplantation. MATERIALS AND METHODS: Five consecutive procedures were prospectively observed. Transplantations of maxillary premolars with optimal root development were included in this study. A 3D-printed replica of the donor tooth was used to prepare a precisely fitting new alveolus at the recipient site before extracting the donor tooth. Procedure time, extra-alveolar time, and number of attempts needed to achieve a good fit of the donor tooth in the new alveolus were recorded. RESULTS: For each transplantation procedure, the surgical time was shorter than 30 minutes. An immediate good fit of the donor tooth in the new alveolus was achieved with an extra-alveolar time shorter than 1 minute for all transplantations. CONCLUSION: These results show that the extra-alveolar time is very short when the surgical guide is used; therefore, the chance of iatrogenic damage to the donor tooth is minimized. The use of a replica of the donor tooth makes the autotransplantation procedure easier for the surgeon and facilitates optimal placement of the transplant.

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.

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.

Investigation of the influence of mallet and chisel techniques on the lingual fracture line and comparison with the use of splitter and separators during sagittal split osteotomy in cadaveric pig mandibles.

In bilateral sagittal split osteotomy the proximal and distal segments of the mandible are traditionally separated using chisels. Modern modifications include prying and spreading the segments with splitters. This study investigates the lingual fracture patterns and status of the nerve after sagittal split osteotomy (SSO) using the traditional chisel technique and compares these results with earlier studies using the splitter technique. Lingual fractures after SSO in cadaveric pig mandibles were analysed using a lingual split scale and split scoring system. Iatrogenic damage to the inferior alveolar nerve was assessed. Fractures started through the caudal cortex more frequently in the chisel group. This group showed more posterior lingual fractures, although this difference was not statistically significant. Nerve damage was present in three cases in the chisel group, but was not observed in the splitter group. A trend was apparent, that SSO using the chisel technique instead of the splitter technique resulted in more posterior lingual fracture lines, although this difference was not statistically significant. Both techniques resulted in reliable lingual fracture patterns. Splitting without chisels could prevent nerve damage, therefore we propose a spreading and prying technique with splitter and separators. However, caution should be exercised when extrapolating these results to the clinic.

Experiencing your own orthognathic surgery: a personal case report.

There has been much research on minimizing the side effects of orthognathic surgery. However, there are very few doctors and researchers who themselves have undergone this surgery. This case report describes the findings of a maxillofacial surgeon who underwent combined orthodontic and orthognathic treatment for correction of Class II malocclusion. In March 2012, the surgeon was referred to an orthodontist, and an orthodontic examination revealed a Class II, division 2, malocclusion with a traumatic palatal bite and attrition of the lower front teeth. The patient underwent alignment of the upper and lower arches, followed by a bilateral sagittal split osteotomy. During this treatment, he made many interesting observations and learned much as a patient, which can have implications in improving the outcomes and quality of care for patients receiving such treatment. Thus, this case report aims to provide a critical perspective of the surgical procedure and treatment from the viewpoint of a maxillofacial surgeon who himself experienced the surgery as a patient.

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.

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.

A case of mental nerve paresthesia due to dynamic compression of alveolar inferior nerve along an elongated styloid process.

Spontaneous paresthesia of the mental nerve is considered an ominous clinical sign. Mental nerve paresthesia has also been referred to as numb chin syndrome. Several potentially different factors have been investigated for their role in interfering with the inferior alveolar nerve (IAN) and causing mental nerve neuropathy. In the present case, the patient had an elongated calcified styloid process that we hypothesized had caused IAN irritation during mandibular movement. This eventually resulted in progressive loss of sensation in the mental nerve region. To our knowledge, this dynamic irritation, with complete recovery after resection of the styloid process, has not been previously reported.

Influence of BSSO surgical technique on postoperative inferior alveolar nerve hypoesthesia: a systematic review of the literature.

OBJECTIVE: The aim of this study was to evaluate the influence of different splitting techniques, namely, "mallet and chisel" versus "spreading and prying", used during bilateral sagittal split osteotomy (BSSO) on postoperative hypoesthesia outcomes. STUDY DESIGN: We systematically searched the PubMed and Cochrane databases (from January 1957 to November 2012) for studies that examined postoperative neurosensory disturbance (NSD) of the inferior alveolar nerve (IAN) after BSSO. RESULTS: Our initial PubMed search identified 673 studies, of which, 14 met our inclusion criteria. From these 14 studies, 3 groups were defined: (1) no chisel use (4.1% NSD/site), (2) undefined chisel use (18.4% NSD/site), and (3) explicit chisel use along the buccal cortex (37.3% NSD/site). CONCLUSION: Study heterogeneity and a frequent lack of surgical detail impeded our ability to make precise comparisons between studies. However, the group of studies explicitly describing chisel use along the buccal cortex showed the highest incidence of NSD. Moreover, comparison of the study that did not use chisels with the 2 studies that explicitly described chisel use revealed a possible disadvantage of the "mallet and chisel" group (4.1% versus 37.3% NSD/site). These results suggest that chisel use increases NSD risk after BSSO.

Is the lingual fracture line influenced by the mandibular canal or the mylohyoid groove during a bilateral sagittal split osteotomy? A human cadaveric study.

PURPOSE: Although the bilateral sagittal split osteotomy (BSSO) is a routinely performed procedure, exact control of the lingual fracture line remains problematic. The purpose of this study was to determine the various lingual splitting patterns in cadaveric human mandibles after a BSSO and the possible influence of the mandibular canal and mylohyoid groove on the lingual fracture line. MATERIALS AND METHODS: The investigators designed and implemented a case series to compare different lingual fracture lines. A standardized SSO was performed on 40 cadaveric hemimandibles using elevators and splitting forceps. The primary outcome variable during this study was the lingual fracture pattern possibly influenced by independent variables: the mandibular canal, the mylohyoid groove, and dental status. Descriptive and analytic statistics were computed for each study variable. RESULTS: Most lingual fractures (72.5%) ended in the mandibular foramen. Only 25% of fractures were "true" Hunsuck fractures, and no "bad splits" occurred. In addition, 35% of lingual fractures ran more than halfway or entirely through the mandibular canal, whereas only 30% of fractures ran along the mylohyoid groove. However, when the lingual fracture ran along this groove, it had a 6-fold greater chance of ending in the mandibular foramen. CONCLUSIONS: The hypothesis that the mandibular canal or mylohyoid groove would function as the path of least resistance was only partly confirmed. The use of splitters and separators did not increase the incidence of bad splits compared with the literature.

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.

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

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