Three-Dimensional Analysis of Long-Term Stability After Bilateral Sagittal Split Ramus Osteotomy Fixed With a Single Miniplate With 4 Monocortical Screws and 1 Bicortical Screw: A Retrospective 2-Center Study

Can the Upper Vermilion and the Nasolabial Fold Be Changed With Orthognathic Surgery?

BACKGROUND

Retrusive profiles show an appearance of aging with an under-projected vermilion and pronounced nasolabial folds due to deficient bone support.

PURPOSE

A study was made of the association between orthognathic surgery and changes in the nasolabial and vermilion areas in patients with retrusive profiles.

STUDY DESIGN, SETTING, SAMPLE

A retrospective cohort study evaluated patients subjected to bimaxillary surgery according to the Barcelona Line (BL) protocol during 2021 at Teknon Medical Center (Barcelona, Spain). Subjects with craniofacial syndromes, facial esthetic procedures, and dental rehabilitations involving lip changes, were excluded.

PREDICTOR VARIABLE

The predictor variable was the timing of cephalometric measures, reported as T0 (preoperatively), T1 (1 month after surgery), and T2 (after 1 year of follow-up).

MAIN OUTCOME VARIABLE

The outcome variable corresponded to the soft tissue changes of the nasolabial and vermilion area, reported as the nasolabial fold length and angle, nasolabial angle, upper lip concavity, vermilion length, and upper lip sagittal distance from BL.

COVARIATES

The covariates comprised patient demographic data, the surgical-orthodontic protocol, and the magnitude and direction of the skeletal movements.

ANALYSES

Descriptive and inferential analyses were performed based on analysis of variance, the Bonferroni test, Pearson's linear coefficient, the nonparametric Mann-Whitney U-test, Kruskal-Wallis test, and multiple linear regression models. Statistical significance was considered for P < .05.

RESULTS

The sample comprised 27 subjects with a mean age of 32.5 ± 11.2 years. A mean decrease in nasolabial angle of 5.5 ± 6° was recorded (P < .001), with a shortening of the nasolabial fold length of 4.4 ± 7.6 mm (P = .019). An increase in upper lip concavity angle of 14.4 ± 12° was recorded (P < .001), along with a vermilion lengthening of 1.6 ± 1.3 mm (P < .001) and an increase in upper lip sagittal distance to BL of 5.7 ± 7.3 mm (P = .001), indicating a more projected and everted upper vermilion.

CONCLUSIONS AND RELEVANCE

When adequate dentoskeletal support is provided by specific positional changes of the jaws planned through orthognathic surgery, the length of the nasolabial fold decreases, and the upper vermilion lengthens and becomes slightly everted.

On the feasibility of minimally invasive Le Fort I with patient-specific implants: Proof of concept

A novel approach to Le Fort I osteotomy is presented, integrating patient-specific implants (PSIs), osteosynthesis and cutting guides within a minimally invasive surgical framework, and the accuracy of the procedure is assessed through 3D voxel-based superimposition. The technique was applied in 5 cases. Differences between the surgical plan and final outcome were evaluated as follows: a 2-mm color scale was established to assess the anterior surfaces of the maxilla, mandible and chin, as well as the condylar surfaces. Measurements were made at 8 specific landmarks, and all of them showed a mean difference of less than 1 mm. In conclusion, the described protocol allows for minimally invasive Le Fort I osteotomy using PSIs. Besides, although the accuracy of the results may be limited by the small sample size, the findings are consistent with those reported in the literature. A prospective comparative study is needed to obtain statistically significant results and draw meaningful conclusions.

Does adjunctive fixation in conjunction with miniplate affect condylar position and morphology after mandibular advancement through bilateral sagittal split ramus osteotomy? A retrospective 3-dimensional CT comparative study

To minimize condylar positional and morphological changes after mandibular advancement through bilateral sagittal split ramus osteotomy (BSSRO), surgeons add either a bicortical screw or a two-hole plate distal to the conventional single miniplate. Since there have been no previous studies investigating the effect of this combination, our study aimed to evaluate the short- and long-term effects of these adjunctive fixation methods (AFM) on condylar positional and morphological changes after mandibular advancement through BSSRO. This retrospective cohort study included consecutive patients with retruded mandibles who were treated in the Department of Orthognathic and TMJ Surgery at West China Hospital of Stomatology, Sichuan University. The patients were divided into two groups based on the primary predictor variable, which was the addition of AFM - either a single bicortical screw or a two-hole plate in addition to the single miniplate. The primary outcome variable was the condylar positional and morphological changes after mandibular advancement through BSSRO. Three-dimensional facial CT scans were obtained at three different time points (preoperatively - T0, 1 week postoperatively - T1, and 1 year postoperatively - T2) and analyzed using ITK-SNAP, 3D Slicer, and SlicerSALT software. Intergroup comparisons were conducted with an independent t-test, with a p-value of <0.05 considered significant. Correlations between the variables were estimated by Pearson correlation. The study comprised 51 patients (32 females, 19 males; mean age 25.13 ± 4.24 years), involving a total of 81 condyles (21 unilateral and 60 bilateral). There was a significant difference in long-term condylar displacement in favor of AFM along with a single miniplate (p < 0.001). The bicortical screw group recorded less condylar displacement than the two-hole plate group horizontally (0.11 mm vs 0.22 mm) and sagittally (0.03 mm vs 0.17 mm), but more vertically (0.85 mm vs 0.03 mm). Bone formation associated with AFM occurred on all condylar surfaces, compared with only three surfaces in the single miniplate group. The adjunctive method in addition to the single miniplate fixation method showed less condylar displacement and more bone apposition after mandibular advancement through BSSRO. The follow-up duration variable was the only significant determinant for volumetric changes in the condyle.

Ultrasound-Guided Suprazygomatic Maxillary Nerve Block Is Effective in Reducing Postoperative Opioid Use Following Bimaxillary Osteotomy

BACKGROUND

Ultrasound-guided maxillary nerve block has recently been described, though its impact upon bimaxillary osteotomy has not been formally investigated.

PURPOSE

The present study was carried out to determine whether the addition of ultrasound-guided maxillary nerve block in subjects undergoing bimaxillary osteotomy reduces opioid use.

STUDY DESIGN, SETTING, SAMPLE

A randomized clinical trial was carried out in adults undergoing bimaxillary osteotomy between April 2019 and January 2020 at Teknon Medical Center (Barcelona, Spain).

PREDICTOR VARIABLE

The predictor variable was the treatment technique used (maxillary nerve block or no block). The subjects were randomized to either receive (test group) or not receive (control group) bilateral ultrasound-guided suprazygomatic maxillary nerve block (5 ml of 0.37% ropivacaine) before surgery.

MAIN OUTCOME VARIABLE(S)

The primary outcome variable was the intravenous methadone requirements in the first two postoperative hours. The secondary outcome variables were postoperative pain, rescue subcutaneous methadone, intravenous remifentanil used intraoperatively, the incidence of postoperative nausea-vomiting, and complications derived from maxillary nerve block.

COVARIATES

Subject age, sex, weight, height, and anesthetic risk, and the duration of surgery were recorded.

ANALYSES

Descriptive and inferential analyses were performed using the χ2 test and Mann-Whitney U test. Statistical significance was considered for P < .05.

RESULTS

The baseline sample consisted of 68 subjects scheduled for bimaxillary osteotomy. The follow-up sample comprised 60 subjects: 30 in the control group (10 females and 20 males, aged 34.0 ± 10.2 years) and 30 in the test group (13 females and 17 males, aged 29.8 ± 10.8 years). The subjects who received maxillary nerve block showed less intravenous methadone use in the first 2 hours postsurgery (median 2.0 mg control group vs 0 mg test group; P < .001), lower pain levels at any time during the first 18 hours postsurgery (median visual analog score 4 control group vs 2 test group; P < .001), and a lesser percentage required methadone (33.3% control group vs 0% test group; P < .01) at 4-18 hours postsurgery.

CONCLUSION AND RELEVANCE

The results obtained suggest that ultrasound-guided maxillary nerve block is a promising anesthetic technique capable of reducing intraoperative and postoperative opioid use, with greater patient comfort in bimaxillary osteotomy.

The effect of different hybrid rigid internal fixation techniques on the postoperative stability following a mandibular advancement using a bilateral sagittal split ramus osteotomy: A retrospective three-dimensional comparative study

OBJECTIVE

To three-dimensionally evaluate post-operative mandibular stability following bilateral sagittal split ramus osteotomies between hybrid and non-hybrid rigid internal fixation techniques.

MATERIALS AND METHOD

Seventy adults with skeletal class II deformity who underwent bilateral split sagittal osteotomy with mandibular advancement were included. Patients were divided into four groups based on their fixation techniques: hybrid technique (HT) groups I, II, and IV received a 4-hole 2 mm miniplate with either a bicortical screw (BS), additional 2 mm 4-hole miniplate, or two-hole miniplate, while non-HT group III received a 4-hole 2 mm miniplate with four mini-screws (MS). Measurements were taken pre-operatively (T0), immediately postoperatively (T1), and ≥1 year after surgery (T2) using 3D Slicer software.

RESULTS

Age, sex, and follow-up period did not correlate significantly with postoperative relapse or stability. Significant differences were observed in the advancement on the right side between groups II, III, and IV and on the left side between groups I, III, and IV. However, the type of surgical intervention showed no significant effect on postoperative relapse and stability. All groups of fixations showed satisfactory stability with irrelevant relapse (< 2 mm or 2°).

CONCLUSION

The study demonstrated satisfactory and comparable stability among different fixation groups on patients undergoing mandibular advancement following bilateral split sagittal osteotomy. The results highlighted the importance of considering the degree of advancement when planning orthognathic surgery and managing postoperative outcomes.

Bilateral sagittal split osteotomy with or without concomitant removal of third molars: a retrospective cohort study of related complications and bone healing

PURPOSE

To carry out a comparative evaluation of the intra- and postoperative complications, and bone healing, following bilateral sagittal split osteotomy (BSSO) with or without concomitant removal of third molars.

MATERIAL AND METHODS

A retrospective analysis was performed of two cohorts subjected to BSSO with the intraoperative removal of third molars (test group) versus the removal of third molars at least 6 months prior to BSSO (control group), comprising at least 1 year of clinical and radiographic follow-up. Partially or completely erupted third molars were extracted immediately before completing the osteotomy, whereas impacted third molars were removed after the osteotomy had been performed. Hardware reinforcement was performed in bimaxillary cases where concomitant molar extraction impeded placement of the retromolar bicortical screw of the hybrid technique.

RESULTS

A total of 80 surgical sites were included (40 in each group). Concomitant extraction of the molar represented a mean increase in surgery time of 3.7 min (p < 0.001). No additional complications occurred in the test group (p = 0.476). The gain in bone density was preserved in both groups (p = 0.002), and the increase was of the same magnitude in both (p = 0.342), despite the fact that the immediate and final postoperative bone densities were significantly higher in the control group (p = 0.020).

CONCLUSION

The results obtained support concomitant molar extraction with BSSO as a feasible option.

Comparison of bicortical, miniplate and hybrid fixation techniques in mandibular advancement and counterclockwise rotation: A finite element analysis study

OBJECTIVE

This study aims to evaluate biomechanical stability and stress distribution of five different fixation types with finite element analysis using 10-mm advancement with or without counterclockwise rotation of the mandible.

MATERIALS AND METHODS

After sagittal split osteotomy, 10-mm advancement was performed in the first group and 10-mm advancement and 10-degree counterclockwise rotation were performed in the second group. One miniplate (M-1), two-miniplate (M-2), one miniplate and a bicortical screw (H), l-shaped bicortical screw (B-1), and inverted l-shaped bicortical screw (B-2) systems were placed. Totally, 120 N force was applied to the models at a 45-degree angle from the lower edge of the symphysis.

RESULTS

The highest values on fixation were seen with miniplate, while the mean values were obtained with bicortical screw system. The highest values on bone were achieved using bicortical screws. One miniplate (M-1) showed both the highest and mean displacement. The highest values in counterclockwise-rotated models increased in all parameters, compared to non-rotated models.

CONCLUSION

In cases in which passive alignment between segments and adequate bone contact are ensured, inverted l-shaped bicortical screw, two-miniplate, or hybrid systems are recommended.

Improving accuracy of the intermediate splint in substantial intermaxillary sagittal discrepancies using an extra anterior anchorage point: technical note

Background

To describe a technical feature that increases the stability of the intermediate splint in patients where bimaxillary surgery with great maxillary/mandibular advancements are planned.

Material and Methods

Prospective evaluation of the intermediate splint dental vertical penetration in patients undergoing bimaxillary surgery where great sagittal discrepancy occur in the anterior sector between the upper and lower jaws when the intermediate splint is placed by adding an extra intermaxillary fixation (IMF) screw (2x9 mm) placed between the central incisors of the maxilla and fixed to the most anterior aspect of the intermediate splint following the direction of the sagittal maxillo-mandibular discrepancy from January to September 2018.

Results

The postoperative evaluation comparing the accuracy of conventional fixation versus fixation with an extra anterior anchorage point through photographic assessment and intraoral digital scanner demonstrated better dental penetration, and therefore improved intermediate splint precision with the latter in all cases

Conclusions

Our results suggest that this is a simple and safe technique that can be easily reproduced and optimizes the outcomes by increasing the accuracy of translation of the planned surgical movements to the operating room.

Key words:Orthognathic surgery, intermediate splint, accuracy, intermaxillary fixation, bone screw.

How to Prevent Mandibular Lower Border Notching After Bilateral Sagittal Split Osteotomies for Major Advancements: Analysis of 168 Osteotomies

PURPOSE

Mandibular ramus bilateral sagittal split osteotomy (BSSO) has been the most commonly used technique in orthognathic surgery for mandibular advancement. However, a common complication of BSSO has been the occurrence of visible and palpable osseous defects at the inferior border of the mandible. The aim of the present study was to determine whether bone grafting of the osseous defect at surgery would reduce the defect at 1 year postoperatively compared with no bone grafting.

MATERIALS AND METHODS

The present retrospective cohort study evaluated patients who had undergone mandibular ramus BSSO for 10 mm or more of advancement. The primary predictor variable was BSSO surgery with bone grafting of the defect (graft group [GG]) versus no bone graft (no graft group [NGG]). The size of the mandibular ramus inferior border defect was the outcome variable considered within the framework of a 1-year postoperative cone beam computed tomography (CBCT) analysis. Gender, age, and the amount of advancement were also considered in the multilevel regression analyses.

RESULTS

From January 2012 to November 2016, 84 patients (168 osteotomies) had undergone BSSO surgery with 10 mm or more of mandibular advancement at the Facesurgery Center (Parma, Italy). Their mean age was 27.4 years (range, 17 to 44 years). Of the 84 patients, 40 had undergone BSSO with bilateral bone grafts (GG). The monocortical block of the iliac crest bone was used as the bone homograft. The final residual defect was measured at 1 year postoperatively on CBCT scans. The GG and NGG had presented with a mean final defect of 0.7 mm (range, 0 to 4.5 mm) and 3.0 mm (range, 0 to 5.5 mm), respectively. Complete absence of the defect was achieved in 72% of the osteotomies in the GG and 9% of the osteotomies in the NGG.

CONCLUSIONS

The use of an iliac crest bone allograft block in the gap between 2 segments during mandibular advancement of 10 mm or more substantially reduced the size and incidence of inferior border defects.

Relevance of 3D virtual planning in predicting bony interferences between distal and proximal fragments after sagittal split osteotomy

After sagittal split osteotomy, the mandibular distal and proximal fragments do not always align themselves passively to one another, resulting in bony interferences and subsequent anomalous settlement of the condyles. Predicting these interferences could be an important ancillary procedure for avoiding intra- and postoperative surgical complications, rendering orthognathic surgery more effective and safer. This study evaluated the relevance of virtual surgical planning in assessing the displacement of the proximal segments after virtual distal segment repositioning, for predicting bony interferences between the segments and thus avoiding related intra- and postoperative surgical complications. The presence of interferences between the distal and proximal segments was compared between virtually predicted (computer-assisted simulation surgery, Dolphin software) and real cases in 100 consecutive patients diagnosed with dentofacial deformities who underwent orthognathic surgery with mandibular repositioning (using a short lingual osteotomy (SLO)). The results indicated that clockwise rotation of the mandible was the mandibular movement most prone to segment interference. Furthermore, virtual planning was sensitive (100%) but had low specificity (51.6%) in predicting proximal and distal segment interferences. This low specificity was due to the software-based automated design of the mandibular osteotomy, where the length of the distal segment was longer than the real SLO, and the mandibular ramus sagittal split was located just behind Spix's spine. Thus, more precise simulated osteotomies are needed to further validate the accuracy of virtual planning for this purpose.

One-year postoperative skeletal stability of 3D planned bimaxillary osteotomies: maxilla-first versus mandible-first surgery

Orthognathic surgery is carried out to correct jaw deformities and to improve facial aesthetics. However, controversy surrounds whether the maxilla- or mandible-first surgery approach leads to better surgical outcomes. In our previous study, we have shown that in most instances, the maxilla-first surgical approach yielded closer concordance with the 3D virtual treatment plan than a mandibular-first procedure. However, the post-operative stability of each approach has not been investigated. Therefore, this one-year follow-up study was set-up and investigated the postoperative skeletal stability of the 3D planned translations and rotations after either the maxilla- or mandible-first surgery. In total, 106 patients who underwent bimaxillary surgery and had an individualized 3D virtual operation plans, received either maxilla-first (n = 53) or mandible-first (n = 53) surgery. 3D printed interocclusal splints were used during surgery to position the jaws. One year postoperatively a cone-beam computed tomography (CBCT) scan was made to assess the effects using the OrthoGnathicAnalyser. The mean sagittal, vertical and transverse relapse was less than 1.8 mm and no significant differences were found in relapse between the maxilla-first or the mandibular-first surgical procedure. Overall, this study shows that 3D virtual planning in combination with an optimised sequencing of osteotomies provides predictable long-term results in bimaxillary surgery.

Jawline Contouring Through an Intraoral Approach in the Context of Bilateral Sagittal Split Osteotomy: A Proof-of-Concept Report

PURPOSE

This report describes a technique to suspend the submandibular space (SS) through an intraoral approach in the context of a bilateral sagittal split osteotomy (BSSO), thus improving the jawline contour and achieving a neck-rejuvenating effect.

PATIENTS AND METHODS

A sample of 6 consecutive patients referred for orthognathic surgery who also sought neck rejuvenation and contouring surgery was selected to implement the technique. The following measurements were used to evaluate the procedure: patient satisfaction with a visual analog scale, photographic assessment, additional operative time, and complications related to the procedure.

RESULTS

The average patient age was 47 years (range, 38 to 57 yr). Three patients were women and 3 were men. All patients were highly satisfied with the results achieved at the jawline. No surgical complications occurred in any case. There was an average increase of only 5 minutes in total operative time for each side.

CONCLUSION

Suspension of the SS through an intraoral approach is an effective, well-tolerated, and technically straightforward method for neck contouring in patients in whom a BSSO procedure is foreseen.

Relapse tendency after BSSO surgery differs between 2D and 3D measurements: A validation study

Bilateral sagittal split ramus osteotomy (BSSO) surgery is used to correct various dento-skeletal deformities. Clinical outcomes are critically dependent on accurate and proper positioning of skeletal units created by BSSO. Monitoring skeletal changes postoperatively is a major part of follow-up. Between January 2015 and December 2015, 24 patients underwent BSSO surgery without any other segmental osteotomy (mean age, 29.9 ± 14.2 [range, 17-67] years; 18 females). Cephalometric X-rays and cone-beam computed tomography scans were performed 6 weeks and 12 months postoperatively. We compared the position displacement at three mandibular points at both postoperative time points using 2- and 3-dimensional analysis separately and examined the relationship between these methods. Horizontally in at least in 14/24 patients, the difference between 2-dimensional and 3-dimensional measurements was >1 mm. Vertically in at least in 16/24 patients, the difference between 2-dimensional and 3-dimensional measurements was >1 mm. A scatter plot with orthogonal regression indicated the relationships between the 2-dimensional measurement and the corresponding 3-dimensional measurement in the horizontal and vertical directions. Skeletal relapse with 2-dimensional-measurements differed significantly from the 3-dimensional measurements. There was no evidence of a relationship between the two types of measurements regarding the direction and the location of the landmarks.