Soft tissue stability in segmental distraction of the anterior mandibular alveolar process. A 2-year follow-up

Anterior Mandibular Segmental Distraction Osteogenesis: A Case Report

Introduction:

Skeletal Angle Class I patients with a severe dental Class II malocclusion are characterized by an unfavourable anterior-posterior relationship between the anterior dentoalveolar area and the skeletal base. Orthodontic alignment posing various treatment difficulties and surgical correction with bilateral sagittal split osteotomy may result in a compromised facial profile. Hence, anterior mandibular segmental distraction osteogenesis has been proposed as an alternative treatment modality for solving facial esthetics, anterior tooth crowding and an unfavourable relationship between the anterior dentoalveolar area and the skeletal base in skeletal Angle Class I patients with a severe dental Class II malocclusion. Limited skeletal relapse with predictable soft tissue changes have been documented in long-term studies. Thus, anterior mandibular segmental distraction osteogenesis seems to be a valuable and predictable surgical method for correction of selected cases of skeletal Class I patients with a severe dental Class II malocclusion.

Case report:

The purpose of this case report is to present the treatment of a 57-year-old female with a skeletal Angle Class I relation and a severe dental Class II malocclusion. Anterior mandibular segmental distraction osteogenesis as well as discussing the current knowledge about this treatment modality.

Conclusion:

The present case report illustrates that establishment of a harmonious relationship between the maxillary and mandibular arch in patients with a skeletal Angle Class I relation and a severe dental Class II malocclusion using anterior mandibular segmental distraction osteogenesis seems to be a predictable and applicable surgical method for selected cases and General Dental Practitioners, orthodontics and maxillofacial surgeons must have knowledge of this treatment modality.

Gingival recessions of lower incisors after proclination by orthodontics alone or in combination with anterior mandibular alveolar process distraction osteogenesis

OBJECTIVES

The aim of this study was to longitudinally compare periodontal conditions in consecutive patients who had orthodontic treatment with proclination of lower incisors either by orthodontics alone or in combination with anterior mandibular alveolar process distraction osteogenesis (DO).

MATERIALS AND METHODS

Nineteen patients had orthodontic treatment with DO, 18 with extraction of lower premolars (Ex), and 18 without extractions (Nonex). Lateral cephalograms were used to evaluate lower incisor proclination, while study casts and intraoral photographs were used to evaluate labial and lingual gingival recessions before (T1) and at an average of 4.5 years (T2) after treatment.

RESULTS

No differences in labial recessions on lower incisors were present between the patient groups despite greater lower incisor proclination in the Nonex and DO groups. The Ex group showed no new development of lingual recessions in contrast to the Nonex (eight sites; two subjects) and DO groups (seven sites; three subjects). Severe lingual recessions (increased ≥1 mm) were more present in the Nonex group (five sites; two subjects) compared to the Ex group (no sites). Proclination of lower incisors of 10° or more either by orthodontic tooth movement or displacement of the whole alveolar process increased the risk of lingual gingival recessions 17 times. This was not the case with labial gingival recessions.

CONCLUSIONS

Orthodontic or surgical proclination of lower incisors beyond a 10° limit increases the risk of inducing lingual gingival recessions.

CLINICAL RELEVANCE

During orthodontic treatment, with or without DO, one should avoid proclining lower incisors more than 10° to decrease the risk of gingival recessions.

[Front Block distraction]

The contribution of the segmental osteotomies in the ortho-surgical protocols is no longer to demonstrate and found a new lease of life thanks to the combination with the bone distraction techniques. The osteotomy of Köle, initially described to close infraclusies, and then used to level very marked curves of Spee has more recently been used to correct anterior crowding. This support is therefore aimed at patients with an incisor and canine Class 2 but molar Class 1 with an isolated mandibular footprint. With minimal orthodontic preparation we can create in two weeks bilateral diastemas that will then be used to align the incisivocanin crowding without stripping or bicuspid extractions. Dental orthodontic movements can be resumed one month after the end of the distraction. This technique is therefore likely to avoid bicuspid extraction and replace some sagittal osteotomy advancement by correction of the overjet. It also helps to correct a incisors labial or lingual tipping playing on differential activation of the cylinders and the distractor. This segmental surgery can be combined with Le Fort 1 surgeries with correction of the transverse and associated meanings, but in a second time, to a mandibular advancement and/or a genioplasty.

Anterior alveolar segmental osteodistraction with a bone-borne device: clinical and radiographic evaluation

PURPOSE

Anterior alveolar osteodistraction is a common method for enlargement of the dentoalveolar process, and bone-borne distraction devices are hypothesized to avoid the risk of dental tipping and periodontal impairment during distraction. The aim of this study was to objectify this thesis and to determine the reliability of bone-borne osteodistraction of the anterior alveolar process.

PATIENTS AND METHODS

The study group consisted of 18 consecutive patients who underwent anterior alveolar segmental distraction with a bone-borne distraction device for the treatment of dental crowding or alveolar retrusion from 2008 through 2011. Clinical and radiologic changes within the apical base and dentoalveolar process were analyzed after bone-borne distraction osteogenesis. All measurements were carried out using cone-beam computed tomography.

RESULTS

Surgery and the postoperative period were uneventful in all patients. Mean alveolar movement was 8.2° ± 2.4°. Skeletal movement was 97.6% and absolute dental tipping was 2.4%. A mean change in the occlusal plane of 1.9° ± 1.1° was verified. The apical base enlargement showed a mean of 7.9 ± 1.4 mm, and the dentoalveolar arch a mean increase of 12.7 ± 2.1 mm. Within the distraction zone, a mean vertical bone loss of 3.5 ± 0.7 mm and a mean horizontal bone loss of 3.9 ± 0.8 mm were seen. After orthodontic gap closure, both were clinically irrelevant, with no need for additional bone grafts. Periodontal impairment (gingival recessions of 1 mm) was observed in 7 patients but affected only the teeth bordering the vertical osteotomy line.

CONCLUSIONS

Bone-borne anterior alveolar osteodistraction is sufficient for enlargement of the apical base and the dentoalveolar arch of the mandible. Skeletal movement of the alveolar segment was predictable and dental tipping was clinically irrelevant. This technique presents further indications and approaches in orthognathic surgery.

Neurosensory and functional evaluation in distraction osteogenesis of the anterior mandibular alveolar process

Neurosensory status and craniomandibular function of 19 patients (mean age 35.2 years, range 17.8-58.8 years) treated by combined surgical orthodontic treatment with distraction osteogenesis of the mandibular anterior alveolar process (DO group) was compared with that in 41 orthodontically treated patients (mean age 22.9 years, range 15.1-49.0 years; control group). Clinical examination took place on average 5.9 years (DO group) and 5.4 years (control group) after treatment ended. Neurosensory status was determined by two-point discrimination (2-pd) and the pointed and blunt test. Lateral cephalograms evaluated advancement of the mandibular alveolar process and possible relapse. There was no significant difference in craniomandibular function and neurosensory status between the groups. Age was significantly correlated with 2-pd at the lips (DO: p=0.01, R=0.575; control group: p=0.039, R=0.324) and chin (DO: p=0.029, R=0.501; control group: p=0.008, R=0.410). Younger patients had smaller 2-pd values. Gender, age, the amount of advancement, and relapse at point B or incision inferior show no correlation with craniomandibular function and neurosensory impairment. DO of the mandibular anterior alveolar process is a valuable and safe method with minor side effects regarding neurosensory impairment.