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

Accuracy of mandibular anterior subapical osteotomy by virtual planning in orthognathic surgery using patient-specific implants

INTRODUCTION

Mandibular anterior subapical osteotomy (MASO) is a complementary procedure during orthognathic surgery to correct proclination or extrusion of the anterior incisors when orthodontic movements fail. The increasing use of patient-specific implants (PSI, titanium plates) in orthognathic surgery has extended to this procedure. Digital orthognathic surgery planning involves manufacturing cutting/drilling guides and specific implants to provide better accuracy and allow complex movement with reduced surgical times compared to conventional planning. This study aimed to assess the accuracy of computer-aided surgery with patient-specific implants in mobilising the MASO segment according to planning.

METHODS

Eleven consecutive patients with mean age 26.82 years (15-41, SD = 10.65) were treated with MASO in addition to other conventional orthognathic procedures incorporating digital planning and patient-specific implants. A three-dimensional "stl" format file of the mandibular dental arch was obtained using an intraoral scanner at the end of the surgical procedure. The accuracy of the MASO segment displacement imposed by PSI was assessed by comparing preoperative 3D-planned mandibular dental arch with the immediate postoperative 3D-measured arch, using surface superimposition and 7 standard dental landmarks. Deviations between the preoperative and postoperative landmarks were calculated and compared to determine whether MASO segment repositioning is sufficiently accurate to be safely used to reposition the incisor/canine axis.

RESULTS

Quantitative analysis revealed an absolute linear difference of 0.66 mm (SD = 0.51) between preoperative 3D digital dental arch impression and postoperative planned 3D dental arch. Overall, the median absolute discrepancies in the x-axis (right-left direction), y-axis (antero-posterior direction), and z-axis (supero-inferior direction) were respectively 0.56 mm (SD = 0.42), 0.77 mm (SD = 0.45) and 0.65 mm (SD = 0.61).

CONCLUSION

A high degree of accuracy between the virtual plan and the immediate postoperative result was observed. According to our results, PSI can be used safely with accuracy in MASO as an adjunct to other conventional orthognathic procedures.

Nonfixated inlay graft for anterior localized mandibular defect

Localized vertical bone defects within the anterior mandibular alveolar ridge frequently pose a unique challenge for functionally and aesthetically pleasing rehabilitation of this area. Causes for significant bone loss in this region may include periodontal disease, postextraction atrophy, trauma, and orthodontic treatment. In the presence of such a defect, ridge augmentation may be obligatory before installation of dental implants. Several surgical procedures, notably bone augmentation techniques, including guided bone regeneration, onlay bone grafting, and interpositional grafts, have been described. However, loss of a single incisor or a few incisors may render these methods complicated for surgical manipulation. In this article, we aim to report the outcome of 4 cases with localized vertical osseous deficits in the anterior mandible, treated by using a technique whereby we utilized the bony defect's margins through a vestibular approach to wedge inlay grafts without additional fixation or distraction hardware, thus overcoming the surgical difficulties and achieving a favorable outcome.

Mandibular bi-directional distraction osteogenesis: A technique to manage both transverse and sagittal mandibular diameters via a lingual tooth-borne acrylic plate and double-hinge bone anchorage

PURPOSE

Mandibular hypoplasia can develop transversely, sagittally, or in both diameters simultaneously. Current techniques achieve either sagittal or transverse expansion with different surgeries. Here, we present a novel method to obtain transverse and sagittal mandibular distraction in one stage.

MATERIALS AND METHODS

The technique consists of a double osteotomy: a dento-alveolar osteotomy comprising four or six anterior teeth and a vertical symphysiotomy underneath. The mandibular basal bone is immediately expanded transversely and fixed to the lower symphysis via a miniplate carrying only one screw on each side that functions as a hinge during active distraction. The plate is connected to the anterior dento-alveolar block with a metal wire ligature. A teeth-anchored lingual distraction system can expand transversely at the alveolar bone level and then sagittally with the anterior dento-alveolar segment wired to the lower plate.

RESULTS

Satisfying and stable results were achieved, confirmed by measurements on serial plaster casts.

CONCLUSION

To the best of our knowledge, this is the first proposal for ortho-surgical correction of both transversal and sagittal mandibular hypoplasia via a bi-directional distraction procedure. A combination of bone-hardware anchorage and dental-anchored distraction systems is suggested. Transmucosal hardware emergence and need for a second surgery to remove bone-borne appliances are avoided.

Front-block technical note: dental and bone borne distractors

Orthognathic surgical technique of segmental osteogenesis distraction of the anterior mandible alveolar process (front-block) was introduced by Triaca and al. in 2001 [2] including lower incisors. The technical note describes distraction process used both, dental-borne distractor and bone-borne distractor. A genioplasty plate was used as a bone-borne distractor. The main point here is that distraction depends on two distraction vectors, a dental one and an alveolar one. It provides good stability and controlled segmental osteogenesis translation and allows sufficient alveolar segmental transport without loading the teeth too heavily.

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.

Diagnosis and management of Silver-Russell syndrome: first international consensus statement

This Consensus Statement summarizes recommendations for clinical diagnosis, investigation and management of patients with Silver-Russell syndrome (SRS), an imprinting disorder that causes prenatal and postnatal growth retardation. Considerable overlap exists between the care of individuals born small for gestational age and those with SRS. However, many specific management issues exist and evidence from controlled trials remains limited. SRS is primarily a clinical diagnosis; however, molecular testing enables confirmation of the clinical diagnosis and defines the subtype. A 'normal' result from a molecular test does not exclude the diagnosis of SRS. The management of children with SRS requires an experienced, multidisciplinary approach. Specific issues include growth failure, severe feeding difficulties, gastrointestinal problems, hypoglycaemia, body asymmetry, scoliosis, motor and speech delay and psychosocial challenges. An early emphasis on adequate nutritional status is important, with awareness that rapid postnatal weight gain might lead to subsequent increased risk of metabolic disorders. The benefits of treating patients with SRS with growth hormone include improved body composition, motor development and appetite, reduced risk of hypoglycaemia and increased height. Clinicians should be aware of possible premature adrenarche, fairly early and rapid central puberty and insulin resistance. Treatment with gonadotropin-releasing hormone analogues can delay progression of central puberty and preserve adult height potential. Long-term follow up is essential to determine the natural history and optimal management in adulthood.

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.

Extreme mandibular dentobasal discrepancy in orthognathic surgery: a proposal for a definitive solution

Some cases in orthognathic surgery present with large discrepancies between the skeletal pattern and the occlusion. If there is little or no sagittal dental discrepancy, but the mandibular basal bone is prognathic, surgical correction can be critical. We describe a two-step procedure to treat these patients. The first step is to adapt the lower alveolar bone to the position of the chin. Distraction osteogenesis in the anterior dentoalveolar mandibular region carries the lower incisors to the same level as the chin. A one-tooth space is opened in the distraction area to obtain a full negative over-jet. Bimaxillary osteotomy can be used to correct class III dentoskeletal malocclusion. Five patients aged 20-40 years have been operated on during the last 2 years. The first step creates harmony between the chin and lower lip, together with a negative over-jet and a true prognathic profile. The class III malocclusion is corrected with a bimaxillary osteotomy. Our two-step plan achieves good occlusion and profile in patients with severe discrepancies between their occlusion and the position of the chin. Dental implants can then be inserted into the gaps left by distraction, which results in a third bicuspid on each side of the mandible.