Relationship of body mass index to stability of mandibular advancement surgery with rigid fixation

Assessment of temporomandibular joint disc position and skeletal stability after bimaxillary surgery

PURPOSE

This study aimed to assess the correlation between temporomandibular joint (TMJ) disc position and skeletal stability and identify the cephalometric measurements associated with relapse after bimaxillary surgery.

METHODS

The participants were 62 women with jaw deformities (124 joints) who underwent bimaxillary surgery. The TMJ disc position was classified into four types (anterior disc displacement (ADD), anterior, fully covered, and posterior) using magnetic resonance imaging, and cephalometric analysis was performed preoperatively and 1 week and 1 year postoperatively. The differences between pre- and 1-week postoperative values (T1) and 1-week and 1-year postoperative value (T2) were calculated for all cephalometric measurements. Moreover, the relationship between skeletal stability using cephalometric measurements, skeletal class, and TMJ disc position was analyzed.

RESULTS

The participants included 28 patients in class II and 34 in class III. There was a significant difference in T2 in SNB between class II mandibular advancement cases and class III mandibular setback cases (P = 0.0001). In T2, in ramus inclination, there was a significant difference between the ADD and posterior types (P = 0.0371). Stepwise regression analysis revealed that T2 was significantly correlated with T1 for all measurements. However, the TMJ classification was not applied to all measurements.

CONCLUSION

This study suggested that TMJ disc position, including ADD, could not affect skeletal stability, including the maxilla and distal segment after bimaxillary osteotomy, and short-term relapse could be related to the movement amount or angle change by surgery for all measurements.

Evaluation of long-term hard tissue relapse following surgical-orthodontic treatment in skeletal class II patients: A systematic review and meta-analysis

This systematic review and meta-analysis was performed to evaluate the long-term hard tissue stability and relapse factors following surgical-orthodontic treatment in skeletal class II patients. A literature search was conducted using Embase, Cochrane Central, Web of Science, and PubMed, yielding 3184 articles published up to January 2019. Risk of bias was assessed following the Cochrane handbook. Ten articles met the inclusion criteria. A total of 1079 patients were followed up for 5-13 years. The qualitative findings showed a variety of extrinsic and intrinsic factors affecting long-term stability. Meta-analysis for the amount and direction of cephalometric landmark displacement in the vertical and sagittal planes showed significant angular increases of ANB and backward relapse of SNB, however within the clinically acceptable range of 4°. In relation to linear measurements, the mean differences in all landmarks were within the clinically acceptable range of 2mm except for gonion. In conclusion, this systematic review showed multiple intrinsic and extrinsic factors responsible for relapse. However, the outcomes of the meta-analysis are limited due to the heterogeneity of data, small number of studies, and inconsistent methods of evaluation. Further high-quality studies utilising standardised three-dimensional methodologies are required to improve the level of evidence.

Comparison of mandibular cortical bone among obese, overweight, and normal weight adolescents using panoramic mandibular index and mental index

OBJECTIVE

The objective of this study is to evaluate the mental index (MI) and panoramic mandibular index (PMI) of a group of adolescent patients in different body mass index (BMI) percentile.

MATERIAL AND METHODS

Subjects were divided into three different groups in accordance to their BMI percentile status: normal weight (35 subjects; mean age, 14.81 ± 2.12 years), overweight (32 subjects; mean age, 14.77 ± 2.56 years), and obese (33 subjects; mean age, 14.06 ± 2.59 years) groups. Mental index (MI) and panoramic mandibular index (PMI) were assessed on panoramic radiographs.

RESULTS

There were statistically significant differences in PMI and MI that were observed among groups (p < 0.0001 and p < 0.001, respectivel). MI and PMI are higher in overweight and obese individuals than in normal-weight.

CONCLUSIONS

Mandibular cortex was found thicker in patients who are obese and overweight compared to normal weight patients. We can suggest that young obese individuals' bone structure can be take in consideration in orthodontic or dental surgical treatment planning.

CLINICAL RELEVANCE

Dense cortical bone may cause some difficulties in orthodontic and surgical treatment. Clinicians should understand obesity and overweight-related jaw bone changes and consider these factors to treat their patients.

Do Patients With Different Mandibular Plane Angles Have Different Time to Relapse After Bilateral Sagittal Osteotomy With Mandibular Advancement?

PURPOSE

This study sought to answer the following question: Do patients with different mandibular plane angles (MPAs) have a different time to relapse after mandibular advancement with bilateral sagittal split osteotomy?

MATERIALS AND METHODS

We performed a retrospective cohort study of patients who underwent bilateral sagittal split osteotomy advancement at Massachusetts General Hospital between 2005 and 2017. The primary predictor variable was MPA, categorized as low (<25°), medium (between 25° and 35°), or high (>35°). The outcome variable was time to relapse (≥2-mm posterior change at the B point). Other covariates included gender, age, temporomandibular joint symptoms, bimaxillary surgery, direction of mandibular rotation, magnitude of advancement, genioplasty, and fixation method. Time to relapse was estimated using the Kaplan-Meier method. Cox and parametric regressions for interval-censored data were performed. P < .05 was considered statistically significant.

RESULTS

The sample was composed of 58 patients (40 female patients), with a mean age of 26.1 ± 4.9 years, grouped as follows: low MPA, n = 15; medium MPA, n = 26; and high MPA, n = 17. Clinically significant relapse was found in 18 patients (31%). Age, temporomandibular joint symptoms, counterclockwise rotation, and magnitude of advancement were statistically significantly different among the 3 groups. When we assessed time to relapse, the Kaplan-Meier method showed that high-MPA patients had a longer mean time at risk and higher estimated probabilities of relapse at different time points compared with low- and medium-MPA patients (P < .05). However, this association was not significant in Cox and parametric regressions.

CONCLUSIONS

Our results suggest that clinically significant relapse was found during the first postoperative year in low-MPA patients and from 2 to 5 years postoperatively in high-MPA patients. Multivariate regression analyses did not show a significant association between MPA and time to relapse, suggesting that other covariates may play a role in the observed time to relapse.

Independent risk factors for long-term skeletal relapse after mandibular advancement with bilateral sagittal split osteotomy

The purpose of this retrospective cohort study was to identify the independent risk factors for long-term skeletal relapse following mandibular advancement with bilateral sagittal split osteotomy. Univariate and multivariate linear regression analyses were performed including nine common risk factors for relapse as independent variables and horizontal/vertical long-term (≥2 years) skeletal relapse as dependent variables. Ninety-six patients were analyzed; 66 were female (68.8%) and the average age of the patients was 29.7±10.5 years. Over an average follow-up of 3.8±1.8 years after an initial mandibular advancement of 8.8±2.4 mm, long-term skeletal relapse of 1.6±1.0 mm horizontal and 0.9±0.7 mm vertical was found. Multivariate analysis identified age, preoperative mandibular plane angle (MPA), bimaxillary surgery, counterclockwise mandibular rotation, and the magnitude of mandibular advancement to be significantly associated with horizontal long-term skeletal relapse. Preoperative MPA, counterclockwise mandibular rotation, and the magnitude of mandibular advancement were significantly associated with vertical long-term skeletal relapse. Thus preoperative MPA, the magnitude of mandibular advancement, and counterclockwise mandibular rotation of the mandible were found to be independent risk factors for both horizontal and vertical long-term skeletal relapse. Although long-term skeletal relapse cannot be avoided entirely, understanding the independent risk factors and their contributions will optimize treatment planning and long-term stability.

Influence of increased body mass index on orthodontic tooth movement and related parameters in children and adolescents: A systematic review of longitudinal controlled clinical studies

Objectives:

To assess the impact of increased body mass index (BMI) on orthodontic tooth movement (OTM) and related parameters in children and adolescents.

Search sources:

A search of six electronic databases and manual searching were performed up to June 2019 without language and time restrictions.

Data selection:

Eligibility criteria were as follows: (1) longitudinal controlled clinical studies; (2) children and adolescents undergoing orthodontic therapy (OT); (3) no systemic diseases; (4) experimental group: patients with increased BMI; and (5) control group: patients with normal BMI.

Data extraction:

Screening, study selection and data extraction were performed; bias within studies was assessed using the Risk of Bias In Non-randomised Studies (ROBINS-I) tool.

Results:

Seven studies were included. One study showed that an increased BMI is associated with less wear-time of removable orthodontic appliances and one study found no significant association. One study showed that an increased BMI is associated with less cooperation during OT; however, not with the treatment results. One study reported higher pain experience during OT in adolescents with than without increased BMI. Two studies showed that increased BMI in adolescents is related to OTM, one with increased and one with decreased rates of OTM, respectively. One study reported an association between increased BMI and incidence of white spot lesions and gingivitis during OT. The ROBINS-I tool showed low to moderate risk of bias within studies.

Conclusions:

The influence of BMI on OTM and related parameters in children and adolescents remains debatable.

A cross-sectional cohort study of gingival crevicular fluid biomarkers in normal-weight and obese subjects during orthodontic treatment with fixed appliances

OBJECTIVES

To investigate the effects of obesity on biomarker levels within lower incisor gingival crevicular fluid (GCF) in subjects undergoing routine fixed appliance orthodontic treatment.

MATERIALS AND METHODS

This was a cross-sectional clinical cohort study. GCF was collected from normal-weight and obese subjects at completion of alignment at least 1 month after placement of 0.019 × 0.025-inch stainless-steel archwires. The primary outcome was the difference in GCF biomarker levels between groups. Secondary outcomes included differences in clinical parameters of plaque and gingival indices, unstimulated whole-mouth saliva, and GCF flow rates.

RESULTS

Thirty-eight subjects (18 male, 20 female) with a mean age of 25.6 (SD, 6.3) years and mean body mass index (BMI) of 22.6 (1.6) in normal-weight and 32.4 (2.2) kg/m² in obese groups were investigated. Apart from BMI (P < .0001), there were no statistically significant differences in essential demographics between groups. Significantly increased levels of the adipokine leptin (P < .009) and the tissue-remodeling biomarker matrix metalloproteinase-9 (MMP9; P < .020) were identified in the obese cohort. For the remainder of the biomarkers, including the RANKL bone-remodeling marker and several inflammatory markers, there were no significant differences between groups. No correlation was observed between plaque index or gingival index for any GCF biomarker for either group (P = .07-1.00).

CONCLUSIONS

This study investigated the GCF biochemical profile of obese and normal-weight subjects undergoing fixed-appliance orthodontic treatment. Significantly increased levels of the adipokine leptin and the tissue-remodeling biomarker MMP9 were identified in the obese group. These data provide evidence of differences in GCF biochemistry between obese and normal-weight subjects undergoing fixed appliance orthodontic treatment.

Surgical Orthodontic Treatment of Severe Skeletal Class II

This paper describes an adult Saudi male patient who presented with a severe skeletal class II deformity. The case was managed with a combination of presurgical orthodontic treatment followed by a double jaw orthognathic surgery and then another phase of orthodontic treatment for final occlusal detailing. Extraction of the four first premolars was done during the presurgical orthodontic phase of treatment to decompensate upper and lower incisors and to give room for surgical setback of the maxillary anterior segment. Double jaw surgery was performed: bilateral sagittal split ramus osteotomy for 8 mm mandibular advancement combined with three-piece Le Fort I maxillary osteotomy, 6 mm setback of the anterior segment, 8 mm impaction of the maxilla, and 5 mm advancement genioplasty. Although the anteroposterior discrepancy and the facial convexity were so severe, highly acceptable results were obtained, both esthetically as well as occlusally.