Anterior open bite correction by Le Fort I osteotomy with or without anterior segmentation: which is more stable?

The Stability of Anterior Open Bite Closure After Bimaxillary Osteotomy

Introduction

The aim of this study was to evaluate the long-term success rate of combined surgical-orthodontic therapy of skeletal anterior open bite.

Materials and Methods

A total of 11 patients with an anterior open bite treated with a combined surgical-orthodontic therapy were retrospectively analysed via lateral cephalometric radiographs and models before treatment, 7-10 days after surgery (T1), one year post-operatively (T2) and two years post-operatively (T3).

Results

Ten patients continued to experience a positive overbite at T2. This decreased to 8 at T3. Three patients experienced relapse and had a negative overbite at T3. The average pre-treatment overbite was greater in the positive overbite group compared to the relapse group. Spearman's correlation analysis revealed a correlation between preoperative maxilla-mandibular plane angle (MMPA) with the overall change in overbite. Friedman's test followed by Bonferroni post-hoc analysis was carried out to identify any statistical significance.

Conclusion

In conclusion, combined surgical-orthodontic treatment achieves good results for anterior open bite. Patients with a high pre-operative MMPA have a higher risk of relapse. Lower anterior facial height ratio to total anterior facial height (LAFH/TAFH) and the amount of impaction do not significantly contribute to the risk of relapse. Long-term stability of overbite for anterior open bite patients should be around 75%.

Retention Strategies for Segmental Lefort I Osteotomies Using Clear Aligners

Clear aligner therapy is becoming a mainstay of contemporary orthodontic treatment. As such wide-spread adoption and case-selection for surgical-orthodontic treatment in patients with Clear aligner therapy is increasing. Passive aligners generally lack adequate rigidity for retention of segmental movements in the immediate postoperative period. In this report we discuss our techniques for maintaining retention in the weeks after segmental maxillary osteotomies by use of a modified clear aligner orthognathic splint, and a custom palatal horseshoe splint, including the relative indications of each method.

Combined orthodontic and surgical open bite correction

OBJECTIVES

To examine the stability of combined surgical and orthodontic bite correction with emphasis on open-bite closure. All study patients were treated with strict and consistent orthodontic and surgical protocols.

MATERIALS AND METHODS

Study inclusion required all patients to have anterior open bites, maxillary accentuated curve of Spee, 36-month minimum follow-up, and no temporomandibular joint pathology. Thirty patients met the inclusion/exclusion criteria. Importantly, segmental upper arch orthodontic preparation (performed by EG) was used. Surgery consisted of a multisegment Le Fort I (MSLFI) combined with a bilateral sagittal osteotomies (BSSO). Surgery was performed (by ADA and LT) at the Department of Dentistry and Maxillofacial Surgery of the University of Verona, Italy.

RESULTS

The long-term open bite and overjet relapse were not statistically significant. The mean transverse relapse of the upper and lower molars was statistically significant. Of great importance, the upper and lower arch widths narrowed together, maintaining intercuspation of the posterior dentition which prevented anterior open bites from developing.

CONCLUSIONS

This study revealed stability of three-dimensional occlusal correction including anterior open bite. Stable open bite closure was achieved by using rigid protocols for orthodontic preparation, surgical techniques, surgical follow-up, and orthodontic finishing.

Vertical stability of different orthognathic treatments for correcting skeletal anterior open bite: a systematic review and meta-analysis

BACKGROUND

Several orthognathic procedures have been applied to correct skeletal anterior open bites (SAOB). Which method is most stable has been debated and no consensus has been reached and there is no conclusive evidence for clinicians to use.

OBJECTIVE

To analyse whether maxillary, mandibular, or bimaxillary surgery provides a better stability.

MATERIALS AND METHODS

A systematic search was conducted up to December 2020 using PubMed, EMBASE, Medline, Scopus, Web of Science, Cochrane CENTRAL, and Google Scholar. We made direct comparisons among the controlled trials and also made indirect comparisons via subgroup analysis on the aspects of occlusional, skeletal, and dento-alveolar stability to assess the overall stability of each method.

RESULTS

Finally 16 cohort studies were identified. At the occlusional level, pooled change in overbite was 0.21 mm in maxillary surgery, 0.37 mm in bimaxillary surgery, and -0.32 mm in mandibular surgery. At the skeletal level, pooled sella-nasion-Point A angle (SNA) was -0.12 degrees in bimaxillary surgery, -0.37 degrees in maxillary surgery and -0.20 degrees in mandibular surgery. The sella-nasion to palatal plane angle (SNPP) relapsed to a statistically significant degree in all samples received single maxillary surgery. Relapse of the sella-nasion-Point B angle (SNB) was 0.47 degrees in mandibular setback, -1.8 degrees in mandibular advancement, and -0.48 degrees in maxillary surgery. The Sella-Nasion to mandibular plane angle (SNMP) relapsed more in procedures involving bilateral sagittal split osteotomy than in other procedures. As for dento-alveolar changes, intrusion of molars and extrusion of incisors took place in most patients.

CONCLUSIONS

Bimaxillary surgery produced the most beneficial post-operative increase in overbite, maxillary surgery led to a lesser but still positive overbite change, and mandibular surgery correlated with some extent of relapse. Skeletally, bimaxillary surgery was more stable than maxillary surgery at both SNA and SNPP; SNB was more stable in mandibular setback than advancement; and SNMP was unstable in both mandibular and bimaxillary surgeries versus maxillary surgery with comparable surgical changes. Dento-alveolar compensation helped maintain a positive overbite.

REGISTRATION NUMBER

CRD42020198088.

Longitudinal recovery pattern of neurosensory deficit after Le Fort I osteotomy

The purpose of this study was to investigate the incidence and recovery pattern of neurosensory deficit (NSD) following Le Fort I osteotomy, and to identify the possible risk factors that might contribute to the complication. A prospective longitudinal observational study on the incidence of NSD was conducted on patients who received Le Fort I osteotomy. Subjective and objective standardized neurosensory assessments were performed preoperatively as the baseline, and postoperatively at 2 weeks, 6 weeks, 3 months, 6 months, 12 months, and 24 months. Possible risk factors for NSD including patient age and sex, surgeon experience, and Le Fort I osteotomy with or without multi-segmentation were analysed. Sixty-six patients (43 female, 23 male) with 132 sides of Le Fort I osteotomy were recruited. The incidence of NSD at 2 weeks, 6 weeks, 3 months, 6 months, 12 months, and 24 months was 81.8%, 59.8%, 39.4%, 19.7%, 7.6%, and 3.2%, respectively. Subjective severity of NSD improved with time. Older age was found to be a risk factor for NSD in the early postoperative period, but there was no difference in the long-term. Patient sex, surgeon experience, and the need for multi-segmentation were not found to be related to the incidence of NSD after Le Fort I osteotomy.

Correction of Malocclusion by Botulinum Neurotoxin Injection into Masticatory Muscles

Botulinum toxin (BTX) is a neurotoxin, and its injection in masticatory muscles induces muscle weakness and paralysis. This paralytic effect of BTX induces growth retardation of the maxillofacial bones, changes in dental eruption and occlusion state, and facial asymmetry. Using masticatory muscle paralysis and its effect via BTX, BTX can be used for the correction of malocclusion after orthognathic surgery and mandible fracture. The paralysis of specific masticatory muscles by BTX injection reduces the tensional force to the mandible and prevents relapse and changes in dental occlusion. BTX injection in the anterior belly of digastric and mylohyoid muscle prevents the open-bite and deep bite of dental occlusion and contributes to mandible stability after orthognathic surgery. The effect of BTX injection in masticatory muscles for maxillofacial bone growth and dental occlusion is reviewed in this article. The clinical application of BTX is also discussed for the correction of dental malocclusion and suppression of post-operative relapse after mandibular surgery.