Maxillary distraction using a trans-sinusal distractor: technical note

Minipig model of maxillary distraction osteogenesis: immunohistochemical and histomorphometric analysis of the sequence of osteogenesis

PURPOSE

To document the sequence of bone formation in a minipig model of Le Fort I distraction osteogenesis (DO) using immunohistochemistry and histomorphometry.

MATERIALS AND METHODS

Female Yucatan minipigs (N = 9) in the mixed-dentition stage underwent bilateral maxillary DO. The distraction protocol was 0 days of latency, with a distraction rate of 1 mm/d for 12 days and 24 days of fixation. Specimens were harvested and divided between the central incisors (18 hemi-maxillae) at the end of DO (n = 6), at mid-fixation (n = 6), and at the end of fixation (n = 6). Sections, including the advancement zone, were stained with hematoxylin-eosin, collagen II, CD34, proliferating cell nuclear antigen, and tartrate-resistant acid phosphatase. Light and fluorescence microscope images (original magnification ×200) were obtained, and percentage of surface area (PSA) of the advancement zone occupied by fibrous tissue, vessels, proliferating cells, osteoid, and bone was determined. An intact maxilla served as the control.

RESULTS

At the end of DO, in the advancement zone, the PSA (mean values) of proliferating cells was 33.16%; fibrous tissue, 52%; vessels, 4.35%; and new bone, 5.45%. At the end of fixation, the PSA of proliferating cells decreased to 10.53%, fibrous tissue to 2.3%, and vessels to 1.5% whereas the PSA of new bone increased to 44.9%.

CONCLUSIONS

The results of this study indicate that the progression of osteogenesis in the maxillary DO wound begins with intense cellular proliferation and vascular fibrous tissue formation and progresses to mature, cancellous bone by the end of fixation. The PSA occupied by mature bone is significantly less than in the control maxilla at the end of fixation. This is consistent with the sequence in the mandibular DO wound.

Long-term stability after craniofacial distraction osteogenesis

PURPOSE

This study was conducted to systematically review long-term skeletal stability after craniofacial distraction osteogenesis.

MATERIALS AND METHODS

Several electronic databases (Old Medline, Medline, Medline In-Process and Other Non-Indexed Citations, Pubmed, Embase, Web of Science, and all EBM reviews [Cochrane Database of Systematic Reviews, ACP Journal Club, DARE, and CCTR]) were searched. Key words used in the search were "distraction," "osteogenesis," "craniofacial," "maxillofacial," "stability," "relapse," and "recurrence." MeSH terms and truncations of these terms were selected with the help of a health science librarian. Abstracts that appeared to contain at least 3 years of postsurgical data were selected. The original articles were then retrieved and evaluated to ensure that they actually had 3 years of data after craniofacial distraction osteogenesis. The references were also hand-searched for possible missing articles that were not indexed in the searched databases.

RESULTS

A total of 118 abstracts were found in the electronic searches. After the first set of selection criteria was applied on these abstracts, 22 articles were retrieved. After the final selection criteria were applied on these 22 articles, only 6 articles were finally selected. These 6 articles reported long-term stability after craniofacial distraction osteogenesis. Sample sizes were small, and the methodological quality of the studies was poor.

CONCLUSIONS

Although, based on the selected studies, craniofacial bone distraction osteogenesis appeared to show long-term stability; limitations of the studies merit caution in interpreting these findings. Some early relapse occurred in the first 3 years postdistraction, but stability was maintained thereafter. Some methodologically sounder studies are needed to confirm the present findings.

Incomplete mobilization of the maxilla resulting in failed maxillary distraction: a case report

Maxillary distraction osteogenesis has become an accepted alternative method in the treatment of patients with severe maxillary hypoplasia in craniofacial syndromes and cleft-related deformities. Insufficient distraction, undesirable soft tissue changes, and occurrence of defective distraction vectors are among the potential complications of intraoral maxillary distraction osteogenesis. A 2-stage procedure combining maxillary advancement by distraction technique with genioplasty and mandibular setback surgery was planned to correct jaw deformities in a 22-year-old patient with severe maxillary retrusion, mandibular prognathism, and excessive lower facial height. In the first stage, osteotomies were performed and maxilla was lightly mobilized after down-fracture. Distractors were placed to the maxilla intraorally. During activation period, the maxilla rotated in a clockwise direction, producing a discrepancy between the planned and the actual vectors. Complete distraction was unsatisfactory and the complication was due to surgical technique. This case report presents the failure of maxillary distraction due to incomplete mobilization of the maxilla. Treatment of the case was achieved by the conventional osteotomy techniques at final operation. The maxilla was successfully advanced to the desired position producing good occlusion and an improved facial profile.

Trans-sinusal maxillary distraction for correction of midfacial hypoplasia: long-term clinical results

Maxillary distraction osteogenesis is indicated in severe angle class III malocclusions, and severe maxillary hypoplasia among some cleft patients and other craniofacial deformities. Twenty patients, aged 8-48 years (mean 17.8+/-10.5 SD) with maxillary and midfacial hypoplasia were treated. The follow-up period was 13-65 months (mean 35+/-16.3 SD). A trans-sinusal maxillary distractor was placed intraorally at each side of the maxilla. The distraction vector was predicted using specialist software, and was transferred to the patients using stereolithographic models and individual templates. A (high) Le Fort I type osteotomy was performed. The amount of activation varied from 8 to 17.5 mm (mean 13.1+/-2.9 SD). Soft and hard tissue formation resulted in complete healing across the distraction gaps. The distractors are almost completely submerged, and can be left in place as long as necessary to avoid relapse. Wit's appraisal was used to measure the stability of the long-term distraction results. Results up to 5 years after distraction showed considerable maxillary advancement with long-term stability. Ongoing growth of the facial skeleton must be considered when distraction osteogenesis is chosen in growing patients.

Long-term results in maxillary deficiency using intraoral devices

Cleft lip and palate patients often present maxillary retrusion and class III malocclusion after cleft repair. Maxillary distraction is a technique that can provide simultaneous skeletal advancement and expansion of soft tissue. Twelve patients with cleft maxillary deficiency due to cleft lip and palate were treated by Le Fort I osteotomy and two intraoral distraction devices that were activated after 4 days of latency period, 1mm per day on both sides. Long-term clinical and cephalometric evaluation of one and two years demonstrate stable results concerning the skeletal, dental and soft tissue relations. In this paper we discuss the advantages of distraction osteogenesis as a method for treatment of maxillary deficiency in cleft patients in terms of stability and relapse. The indications for maxillary distraction: (1) Moderate and severe retrusion that needs large advancement as in cleft lip and palate patients. (2) Forward and downward lengthening of the maxilla with no need for intermediate bone graft. (3) Growing patients. In conclusion, maxillary distraction in moderate or severe retrusion, as in cleft patients offers marked maxillary advancement with long-term stability.