Concomitant Removal of Mandibular Third Molars During Sagittal Split Osteotomy Minimizes Neurosensory Dysfunction

The comprehensive on-demand 3D bio-printing for composite reconstruction of mandibular defects

Background

The mandible is a functional bio-organ that supports facial structures and helps mastication and speaking. Large mandible defects, generally greater than 6-cm segment loss, may require composite tissue reconstruction such as osteocutaneous-vascularized free flap which has a limitation of additional surgery and a functional morbidity at the donor site. A 3D bio-printing technology is recently developed to overcome the limitation in the composite reconstruction of the mandible using osteocutaneous-vascularized free flap.

Review

Scaffold, cells, and bioactive molecules are essential for a 3D bio-printing. For mandibular reconstruction, materials in a 3D bio-printing require mechanical strength, resilience, and biocompatibility. Recently, an integrated tissue and organ printing system with multiple cartridges are designed and it is capable of printing polymers to reinforce the printed structure, such as hydrogel.

Conclusion

For successful composite tissue reconstruction of the mandible, biologic considerations and components should be presented with a comprehensive on-demand online platform model of customized approaches.

A new rationale for preservation of the mandibular third molar in orthognathic patients with missing molars

Controversies exist regarding the need for prophylactic extraction of mandibular third molars in patients who plan to undergo orthognathic surgery. An 18-year-old male patient was diagnosed with mandibular prognathism and maxillary retrognathism with mild facial asymmetry. He had a severely damaged mandibular first molar and a horizontally impacted third molar. After extraction of the first molar, the second molar was protracted into the first molar space, and the third molar erupted into the posterior line of occlusion. The orthognathic surgery involved clockwise rotation of the maxillomandibular complex as well as angle shaving and chin border trimming. Patients who are missing or have damaged mandibular molars should be monitored for eruption of third molars to replace the missing posterior tooth regardless of the timing of orthognathic surgery.

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.

Do positional changes of the inferior alveolar canal after sagittal split mandibular osteotomy affect neurosensory recovery?

The purpose of this study was to assess the pre- and postoperative position and dimensions of the inferior alveolar canal (IAC) following sagittal split osteotomy (SSO) and identify any association with postoperative neurosensory deficit (NSD) at 1 year. This retrospective cohort study enrolled consecutive patients who had SSO performed to correct skeletal malocclusion. The pre- and postoperative cone beam computed tomography data were superimposed to visualize differences in IAC position and dimensions. Subjective and objective neurosensory tests were used to determine NSD in the inferior alveolar nerve distribution. A total of 20 subjects were included. The preoperative distance from the lateral cortex of the IAC to the inner aspect of the lateral cortex of the mandible was significantly greater in sides with NSD when compared to sides without NSD (P =  0.01). A significantly greater reduction in the postoperative distance measurement was seen in sides with NSD when compared to sides without NSD (P =  0.01). The magnitude of mandibular movement was significantly increased in sides with NSD (P = 0.02). The preoperative location of the IAC, as well as certain changes in the mediolateral and vertical positions as a result of SSO, are risk factors for postoperative NSD.

Management of Impacted Third Molars

Impacted third molars occur in a significant number of patients and often require treatment because of presence of symptoms and/or disease. Management of these teeth typically involves referral to oral and maxillofacial surgeons for diagnosis, treatment planning, and ultimate removal if indicated. Proper diagnosis and treatment planning helps optimize surgical results at each stage of the procedure, and ultimately patient outcomes. Adherence to proper surgical techniques helps minimize risks and complications associated with the procedure. Multiple alternative surgical techniques also exist for uncommon, but potentially complicated, situations that arise with some impacted third molars.

3-Dimensional prediction of pre-surgical decompensation after atypical extractions and soft tissue simulation for ortho-surgical management of skeletal Class III malocclusion: A case report

Three dimensional imaging systems whether in the form of digital models, facial scanning or dolphin software play an important role in proper diagnosis and treatment planning of the orthosurgical cases. This case report highlights importance of three-dimensional treatment planning in the ortho-surgical management of the patient with skeletal Class III malocclusion involving atypical extraction. On clinical examination, patient had concave profile, prominent chin, deficient midface, flat cheekbone contour and prominent nasal projection. He had Class III molar and canine relation bilaterally with missing 12 (previously extracted), negative overbite and overjet with discordant maxillomandibular midlines. After 3-dimensional digital model set-up for occlusion planning and dolphin simulation for soft tissue prediction, extraction of left maxillary lateral incisor was planned followed by maxillary advancement and mandibular setback surgery and finish the occlusion in Class II molar relationship. After the orthodontic and orthognathic surgical treatment, the skeletal and dental imbalance was corrected, and most of the treatment objectives were achieved and patient was extremely satisfied with his facial profile. The treatment results were stable at the 3 years follow-up.

Orthosurgical Management of Class III Malocclusion Emphasizing the Pivotal Role of CBCT

Management of skeletal class III malocclusions in a nongrowing individual remains a challenging and arduous task for the orthodontist. The skeletal class III malocclusion is often not amenable to camouflage procedures and requires a surgical correction of the underlying skeletal bases to achieve esthetic and functional treatment results. These patients often require one or more extractions to remove the preexisting dentoalveolar compensations prior to the surgical procedure which is undertaken as part of presurgical orthodontics. Postsurgical orthodontics is often of limited duration and is concerned with the settling of occlusion and obtaining tight cuspal interdigitation. Cone-beam computed tomography is a recent innovation which has revolutionized imaging in dentistry. Within orthodontics, it has proven to be of great value in orthosurgical planning and evaluation of posttreatment results including root parallelism and root resorption. This case report describes orthosurgical management of class III malocclusion utilizing cone-beam computed tomography in treatment planning.

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.

Surgical Site Infections Following Bimaxillary Orthognathic, Osseous Genioplasty, and Intranasal Surgery: A Retrospective Cohort Study

PURPOSE

Frequency estimates of surgical site infection (SSI) after orthognathic surgery vary considerably. The purpose of this study was to determine the incidence and site of SSIs and associated risk factors after bimaxillary orthognathic, osseous genioplasty, and intranasal surgery.

MATERIALS AND METHODS

The authors executed a retrospective cohort study of patients with a bimaxillary developmental dentofacial deformity (DFD) and symptomatic chronic obstructive nasal breathing. All patients underwent at a minimum Le Fort I osteotomy, bilateral sagittal ramus osteotomies (SROs), septoplasty, inferior turbinate reduction, and osseous genioplasty. The primary outcome variable studied was the incidence and site of SSI. Predictor variables were type and extent of prophylactic antibiotic used, demographic (age and gender), and anatomic (pattern of DFD, surgical site, and presence of third molar).

RESULTS

Two hundred sixty-two patients met the inclusion criteria. Their average age at surgery was 25 years (range, 13 to 63 yr) and there were 134 female patients (51%). The major presenting patterns of DFD included long face (30%) and maxillary deficiency (25%). Forty percent of patients undergoing an SRO and 47% of those undergoing a Le Fort I osteotomy underwent simultaneous removal of a third molar. Ninety percent of patients received cefazolin or cephalexin antibiotics. Overall, 5 of 1,048 (0.5%) osteotomy sites sustained an infection, including 1 chin and 4 ramus SSIs. There were no delays in bone healing. Fixation hardware removal was not required in any patient who developed an infection. Two of the 25 patients (8%) given clindamycin prophylaxis developed an SSI, whereas 3 of 237 patients (1%) receiving cefazolin did. Three of the 4 patients who developed an SRO SSI underwent simultaneous removal of an erupted or partially erupted mandibular third molar (P < .05).

CONCLUSIONS

In this study, the incidence of SSI was limited to 1% of patients who were given cefazolin or cephalexin extended for 5 days. The removal of an erupted or partially erupted mandibular third molar in conjunction with an SRO was associated with risk of SSI, but the incidence remains low.

Concomitant Third Molar Removal During Sagittal Split Osteotomy of the Mandible

It is described in textbook about management of third molar in orthognathic surgery that "ideally, the third molars should be removed 9 to 12 months before sagittal split osteotomy (SSO)." At the Chang Gung Craniofacial Center, the authors always remove mandibular third molars during SSO, because: removal of third molars at the same time of SSO could reduce psychological stress on patients by saving 1 surgical procedure under local anesthesia, better exposure of impacted third molars could be facilitated by sagittal split of buccal cortical plate, rigid fixation could be performed without difficulty by our fixation method using plates and screws crossover anterior oblique line. Strong force during the elevation of third molars, however, may result in the fracture of distal segment of SSO, where the buccal cortical plate is relatively thin because of the presence of third molar. Therefore, more care needs to be taken in the surgical technique, which is different from ordinary tooth extraction. In this paper, the details of surgical procedure of third molar removal during SSO were reported.

Preoperative removal of lower third molars and bilateral sagittal split osteotomy in the UK

To find out what consultants in Oral and Maxillofacial Surgery (OMFS) in the UK think about complications of bilateral sagittal split osteotomy (BSSO) in relation to lower third molars we organised a national postal questionnaire during 2012-13. Of 378 consultants, 192 practised orthognathic surgery of whom 132 replied (a 69% response rate). Eighty-one respondents routinely removed lower third molars before BSSO; 51 did not. Eighty-nine respondents thought that there was an increased risk of complications if third molars were present at the time of BSSO, mainly an increased risk of unfavourable fractures. Forty-three respondents did not think there was an increased risk of complications of BSSO when third molars were present. Of the 81 who routinely removed the lower third molars, 13 removed them within the six-month period before BSSO, 56 removed them 6-12 months before, and 11 removed them more than 12 months before. There seemed to be no difference in self-reported unfavourable fracture rates between those surgeons who routinely removed lower third molars and those who did not. The results of the questionnaire showed that there was considerable variation in surgical practice across the UK in the management of lower third molars before BSSO, both in terms of whether or not to remove these teeth at all, and if so, when to remove them.

[National survey: Avulsion of included wisdom teeth in mandibular orthognathic surgery]

INTRODUCTION

There is no recommendation concerning wisdom teeth (WT) extraction in mandibular orthognathic surgery. We carried out an investigation among the members of the French Society of Stomatology and Oro-maxillofacial Surgery (SFSCMFCO), in order to evaluate the practices and habits of maxillofacial surgeons in this field.

MATERIALS AND METHODS

We emailed the 424 members of the SFSCMFCO with a questionnaire.

RESULTS

We obtained 143 feedbacks that could be exploited. In total, 72.5% of practitioners prefer WT to be extracted before performing a bilateral sagittal spilt osteotomy (BSSO). In this case, a period of 6 months between the two surgeries was considered as desirable by more than 70% of the surgeons. In total, 74.6% of the surgeons thought that the presence of WT could make a BSSO more complicated. However, 73.9% of the surgeons would not postpone the BBSO in a patient ready for surgery but with remaining impacted WT.

DISCUSSION

A majority of surgeons think that the presence of impacted WT may complicate a BSSO and increases the risk of bad split. Most of the authors recommend extracting the impacted WT 6 months before BSSO at least. However, these potential complications are easy to overcome and don't compromise the final result. Therefore, we think that impacted WT should not delay a BSSO if the orthodontic preparation makes the patient ready for surgery.

Bad splits in bilateral sagittal split osteotomy: systematic review and meta-analysis of reported risk factors

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.

Bad splits in bilateral sagittal split osteotomy: systematic review of fracture patterns

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.

Comparison of skeletal stability after sagittal split ramus osteotomy with and without extraction of the third molar in patients with mandibular prognathism

PURPOSE

The purpose of this study was to evaluate, through cephalometric analysis, the skeletal stability following BSSRO performed with and without extraction of the third molar, and to examine the healing of the extraction sockets through computed tomography (CT).

PATIENTS AND METHODS

Sixty Japanese patients (male: 14, female: 46) diagnosed with mandibular prognathism were included in this study. While 30 patients underwent BSSRO along with extraction of the third molar (extraction group), the other 30 patients underwent BSSRO alone (non-extraction group). Skeletal stability was assessed using axial, frontal, and lateral cephalograms. CT scans were obtained 1 week after surgery and at the 1-year follow-up for all the patients. CT value was measured at the point of the extraction socket on the horizontal plane parallel to the Frankfurt plane using computer software (SimPlant 2011; Materialise Dental, Leuven, Belgium). The region of interest (ROI) was approximately 4 mm(2) and the mean value was recorded. Healing of the extraction sockets was examined through CT 1 year postoperatively.

RESULTS

There were no significant differences between the groups for any of the parameters at any observation interval. In the extraction group, there were significant differences between the values of CT obtained 1 week postoperatively and 1 year postoperatively in the extraction socket (P = 0.0003).

CONCLUSION

The results of this study indicate that there is no significant difference in the skeletal stability between BSSRO performed with and without third molar extraction.