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.     

What factors affect the attachment of the inferior alveolar nerve to the buccal plate following sagittal split osteotomy?

PurposeThis study aimed to assess the factors that can possibly affect the positioning of the inferior alveolar nerve (IAN) in the proximal or distal segment following sagittal split osteotomy (SSO).Materials and methodsThis was a prospective cohort study. The patients were assigned according to the position of the IAN: the IAN was attached to the buccal plate in group 1 (27 SSOs), while it was in the distal segment in group 2 (83 SSOs).ResultsThe mean of the buccolingual thickness of the proximal segment at the vertical cut of the osteotomy (BLTP) was 5.0 ± 0.62 mm in group 1 and 4.16 ± 0.72 mm in group 2. The mean of the distance between the IAN and the external cortical bone at the distal of the second molar before the osteotomy (IANB) was 0.5 ± 0.24 mm in group 1 and 1.24 ± 0.45 mm in group 2. There were significant differences for the mean BLTP and IANB between the two groups (P = 0.001).ConclusionIt seems that the thickness of the buccal plate of the proximal segment, the distance from the IAN to the external cortical bone, the osteotomy technique, and the presence or absence of impacted third molars may be associated with the positioning of the IAN following SSO.     

How does bone thickness affect the split pattern of sagittal ramus osteotomy?

This study examined the influence of bone thickness on the split pattern of sagittal ramus osteotomy at 62 sites using Dolphin 3D software. Four measurements of thickness were obtained from the preoperative computed tomography scans: measurement A was made 1.5 mm above the lingula, using the coronal and sagittal planes; measurement B was made at the same height as measurement A and 1 mm from the anterior border of the ramus; measurement C was obtained 5 mm distal to the last molar and 5 mm below the upper border of the mandible; measurement D was made in the area between the first and second molars, 6 mm above the mandibular border. Three-dimensional postoperative images were used to classify the split pattern into types, based on the classification of Plooij et al. The data were analyzed using the Kruskal–Wallis test, followed by Dunn post-hoc test. Thirty-five sagittal splits were type I, one was type II, 19 were type III, and seven were type IV. Type I presented the greatest thickness, whereas type IV presented the lowest. There was a statistically significant difference in thickness only for measurement A, when types I and IV were compared. The results indicate that thinner mandibular rami are more prone to bad splits.     

Which kind of miniplate to use in mandibular sagittal split osteotomy? An in vitro study

This study verified the resistance to displacement of six miniplate fixation methods after sagittal split osteotomy (SSO). SSO was performed in 30 polyurethane synthetic mandible replicas. The distal segments were advanced (4 mm) and specimens were grouped according to the fixation method: four-hole standard miniplate; four-hole locking miniplate; six-hole standard miniplate; six-hole locking miniplate; six-hole standard sagittal miniplate; six-hole locking sagittal miniplate. Biomechanical evaluation was performed by applying compression loads to three points on the second molar region, using an Instron universal testing machine until a 3 mm displacement of the segments occurred. Compression loads able to produce 3 mm displacement were recorded in kN and subjected to analysis of variance (P < 0.01) and Tukey's tests for comparison between groups (P < 0.05). The locking sagittal miniplate showed higher resistance to displacement than the regular four- and six-hole locking and standard miniplates. No significant differences were observed between the locking sagittal miniplate and the regular sagittal or the four-hole locking miniplates. Two of the three groups with the best results had locking plate fixation methods. Fixation of SSO with a single miniplate is better accomplished using six-hole locking sagittal miniplates, six-hole standard sagittal miniplates, or four-hole locking miniplates; these methods are more resistant to displacement.     

Does the presence of third molars during sagittal split mandibular ramus osteotomy favour complications? Systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to assess whether the presence of inferior third molars during sagittal split mandibular ramus osteotomy increases the risk of intraoperative and postoperative complications. The PRISMA protocol was followed in this study, and the review was registered in the PROSPERO database (CRD42020147642). A search was conducted in the MEDLINE (PubMed), Web of Science, Cochrane Central, and Scopus databases on November 1, 2021. Nineteen articles were included, and the variables analysed were unfavourable fractures, infection, neurosensory disturbance, removal of osteosynthesis material, and duration of surgery. Meta-analyses were performed for the variables unfavourable fractures (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.58–1.57, P = 0.84), infection (RR 0.75, 95% CI 0.48–1.18, P = 0.21), and neurosensory disturbance (RR 1.55, 95% CI 0.61–3.91, P = 0.35); no statistically significant difference in the risk of these variables was found between the groups with and without third molars. The third molars did not increase the need to remove fixation material, but increased the surgery time. The presence of the third molar during sagittal split mandibular ramus osteotomy appears not to increase the risk of intraoperative and postoperative complications. The results presented here must be interpreted with caution due to the heterogeneity presented by the observational studies included.     

Mandibular sagittal split osteotomy: is a bicortical 2-screw osteosynthesis adequate?

The aim of this study was to prospectively evaluate the accuracy and reliability of the use of the Hunsuck/Epker–type mandibular split osteotomy together with osteosynthesis with placement of 2 bicortical positioning screws without the adjunctive use of a postoperative maxilla-mandibular fixation in the treatment of mandibular dentofacial deformities. We analyzed the clinical and radiologic data of 54 patients with dentofacial deformities. We recorded age and sex, status of healing, and complications. Postsurgical complications that were recorded as minor did not require surgical intervention, whereas major complications required further surgical intervention. Fifty-one patients (94.5%) had a successful treatment outcome without complications, 13 patients (24%) developed minor complications, and 3 patients (5.5%) developed screw loosening requiring hardware removal and reosteosynthesis. The present study has demonstrated that Hunsuck/Epker–type mandibular split osteotomy together with osteosynthesis with placement of 2 bicortical positioning screws without the adjunctive use of a postoperative maxilla-mandibular fixation in the treatment of mandibular dentofacial deformities results in a low rate of major complications with a high rate of success     

Do lower third molars increase the risk of complications during mandibular sagittal split osteotomy? Systematic review and meta-analysis

The aim of this systematic review was to investigate whether the presence of third molars (3Ms) during sagittal split osteotomy of the mandible increases the risk of complications. Searches were conducted using MEDLINE via PubMed, LILACS, Cochrane Central, Scopus, DOSS, and SIGLE via OpenGrey up to December 2020. Fifteen articles were included for evaluation and 14 in the meta-analysis, with a total of 3909 patients and 7651 sagittal split osteotomies (670 complications). Inferior alveolar nerve (IAN) exposure in the proximal segment was the most frequent complication (n = 409), followed by bad splits (n = 151). Meta-analysis revealed no significant increase in the incidence of 3M-related IAN exposure (P = 0.45), post-surgical infections (P = 0.15), osteosynthesis material removal (P = 0.37), or bad splits (P = 0.23). The presence of 3Ms was associated with a reduced risk of nerve disorder (P = 0.05) and favoured bad splits in the lingual plate (P = 0.005). The quality of evidence was very low, mainly due to non-randomized study designs, high risk of bias, inconsistency, and imprecision. This systematic review suggests that the removal of 3Ms before sagittal mandibular osteotomy does not reduce the incidence of complications. Thus, we recommend future better-designed studies with rigorous methodologies and adjustments for confounding factors.     

Patients' evaluation of the final result of sagittal split osteotomy: is it influenced by impaired sensitivity of the lower lip and chin?

The purpose of this article was to evaluate whether neurosensory disturbances such as impaired sensitivity of the lower lip and chin influence patients' final evaluation of the treatment result. Information about the patients' degree of satisfaction and about lip and chin sensitivity were obtained from final follow-up documents of 215 patients. All patients had undergone sagittal split ramus osteotomy for mandibular advancement. In patients with normal sensitivity on both sides of the lower lip and chin, the degree of satisfaction was equally distributed at a very high level through all age groups. Among those with some degree of numbness on either or both sides of the lower lip and chin, patients in the younger quarter and middle half of the group were as satisfied as those with normal sensitivity, while those in the oldest quarter with impaired sensitivity demonstrated a lower degree of satisfaction than the rest of the patients. Although the difference was not statistically significant, the finding strongly indicates that older patients seem to suffer more from neurosensory disturbances than do younger patients with similar conditions.     

Effects of sagittal split ramus osteotomy on temporomandibular disorders in seventy‐two patients

Preoperative and postoperative temporomandibular disorders (TMDs) were observed in 72 patients before surgical‐orthodontic treatment and about 2 years after bilateral sagittal split osteotomy. Prevalence and degree of TMD were assessed using the modified clinical dysfunction index of Helkimo. A total of 49 women and 23 men (mean age 32 years) were included in the study. To find out which patients benefit most from the treatment, the sample was classified into subgroups—myogenous, arthrogenous, or both components of TMD. The prevalence of clicking and headache decreased significantly with the treatment, while the incidence of crepitation increased. In general, severity of the dysfunction was greatly reduced. Furthermore, multiple regression analysis showed that patients with excessive overjet and previous occlusal splint therapy benefit most from orthognathic treatment. In addition, patients with signs of mainly myogenous origin got more relief from their dysfunction than patients with mainly arthrogenous components of TMD. The results suggest that in patients with severe maxillomandibular discrepancy surgical‐orthodontic therapy is a good choice of treatment for reducing myogenous TMD pain and discomfort.     

Does the use of low-level light therapy postoperatively reduce pain,oedema, and neurosensory disorders following orthognathic surgery? A systematic review

The aim of this study was to evaluate the efficacy of low-level light therapy (LLLT) in improving pain, oedema, and neurosensory disorders of the inferior alveolar nerve (IAN) after orthognathic surgery. This systematic review was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Searches were conducted in the PubMed, Embase, and Web of Science databases for randomized clinical trials (RCTs) published up to September 2020. After evaluating eligibility, 15 RCTs were selected. None of the studies reported an evaluation of all of the outcomes within the same publication. It was possible to determine the effect of LLLT in controlling pain following orthognathic surgery. Of the three studies evaluating this outcome, all observed a positive effect. Of the four studies that evaluated oedema, two found a positive effect. Of the 11 studies that evaluated neurosensory disorders of the IAN, all of them observed a positive effect, at least in one of the sensory evaluation tests. A meta-analysis was not possible due to the heterogeneity across studies. Considering the limitations of this review, but given the fact that LLLT is a minimally invasive intervention, its use merits consideration in immediate postoperative orthognathic surgery.     

Does early repair of trigeminal nerve injuries influence neurosensory recovery? A systematic review and meta-analysis

This systematic review and exploratory meta-analysis of the available evidence was performed to examine whether early nerve repair of lingual nerve (LN) and inferior alveolar nerve (IAN) injuries has an effect on neurosensory recovery. A literature search was conducted to identify relevant studies meeting the inclusion criteria. Two reviewers independently evaluated the methodological quality of the included studies and the risk of bias using the ROBINS-I quality assessment tool. For the quantitative analysis, data were pooled using the Mantel–Haenszel random-effects method due to the clinical heterogeneity across the studies. Sensitivity and subgroup analyses were performed based upon the group definition of timing from injury to nerve repair, with breakpoints of 2, 3, and 6 months. A total 1236 citations were identified, with a final 13 studies included in the systematic review. A clear definition of ‘early’ versus ‘late’ repair was not reported in six studies, allowing only seven to be included in the meta-analysis. The effect of early repair on functional sensory recovery was found not to be significant in nine studies, while four studies found a significant effect of early intervention. The meta-analysis showed a combined success rate of 93.0% for the early group and 78.5% for the late group. The odds of improvement were 5.49 (95% confidence interval 1.40–21.45) in the 3-month breakpoint studies and 2.28 (95% confidence interval 1.05–4.98) in the 6-month studies. A trend towards early repair achieving better functional sensory recovery outcomes was observed, but the specific time period is unknown.     

Is injury to the inferior alveolar nerve still common during orthognathic surgery? Manual twist technique for sagittal split ramus osteotomy

The osteotomy in a bilateral sagittal split ramus osteotomy (BSSRO) is made in close proximity to the inferior alveolar nerve (IAN), so direct damage to the nerve and irreversible neurosensory deficit may result. The aim of this study was to compare the incidence of injury to the nerve when a conventional osteotomy using an osteotome was made, with that after manual twist splitting. We retrospectively reviewed the casenotes of 769 consecutive patients who had bilateral SSRO either alone or with a simultaneous maxillary procedure by a single surgeon from May 2009 ? October 2016. Patients were divided into two groups based on the technique used. Those in the first group had conventional split osteotomy using an osteotome and hammer for splitting (conventional group, 736 sides), and in those in the second group the manual twist technique was used (manual group, 802 sides). Patients who sustained Sunderland fifth degree injuries were identified from an existing record of nerve repairs. Fisher's exact test was used to evaluate the significance of the number of injuries to the nerve in each group. Conventional osteotomy and hammer-assisted SSRO resulted in 8/736 (1.1%) injuries to the IAN, whereas the manual twist splitting technique resulted in 1/802 injuries (0.1%). Our results confirm that the manual twist splitting technique significantly reduces the incidence of injury to the IAN, though the overall incidence was low.     

Does platelet-rich fibrin increase stability of the maxilla following Le Fort I osteotomy? A single-blind clinical trial study

This single-blind clinical trial study aimed to assess the efficacy of platelet-rich fibrin (PRF) in increasing stability following Le Fort I osteotomy for maxillary advancement. Patients who underwent Le Fort I osteotomy for maxillary advancement were assigned randomly into two groups: in group 1 (the study group, n = 22) PRF was placed in the osteotomy sites following fixation, while no PRF was used in group 2 (the control group, n = 22). Lateral cephalograms obtained preoperatively (T0), immediately after surgery (T1), and 1 year after surgery (T2) were compared between the two groups, and the amount of relapse was determined. The amount of maxillary change (relapse) at the A point in relation to the x-axis was 0.45 ± 0.67 mm in group 1 and 1.86 ± 0.56 mm in group 2. There was a significant difference in mean relapse in relation to the x-axis between the two groups 12 months after osteotomy (p < 0.001). The mean maxillary change (relapse) in relation to the y-axis was 0.77 ± 1.15 mm in group 1 and 2.25 ± 1.22 mm in group 2. Analysis of the data demonstrated a significant difference in mean relapse in relation to the y-axis between the two groups (p < 0.001). PRF may enhance the stability of the maxilla following Le Fort I osteotomy. Based on the results of this study the administration of PRF should be considered whenever possible.     

Comparative evaluation of different fixation techniques of the sagittal split ramus osteotomy in 10 mm advancements: Mechanical testing and screw insertion torque

Purpose

To compare the mechanical characteristics of five techniques for the functionally stable fixation of simulated sagittal split ramus osteotomy with 10 mm of advancement and to evaluate the screw insertion torque.

Does the use of prophylactic antibiotics decrease implant failure?

The use of prophylactic antibiotics in implant dentistry is controversial. Given the known risks of antibiotic treatment and lack of consensus on using antibiotics at the time of implant insertion, the purpose of this article was to review available studies on use of perioperative prophylactic antibiotics at the time of implant placement and to provide evidence-based recommendations for antibiotic use. The reviewed studies suggest that a single preoperative dose of 2 g amoxicillin 1 hour before implant placement or 1 g amoxicillin 1 hour preoperatively and 500 mg 4 times daily 2 days postoperatively can reduce the rate of implant failure.