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

Midfacial Protraction With Skeletal Anchorage After Pterygomaxillary Separation

The present article reports the treatment of a 7-year-old girl with maxillary hypoplasia associated with multiple tooth agenesis through maxillary protraction with skeletal anchorage and pterygomaxillary separation. Two titanium mini-plates were placed in the lateral region of the nasal cavity and used as anchorage for maxillary protraction with a reverse-pull facemask. Pterygomaxillary separation was also performed to enhance the effects of maxillary protraction. One week after surgery, 300 g of force was applied on each side to protract the maxilla. Active treatment time was 4 months, with 12 additional months of follow-up. Analysis of the cone beam computed tomography images demonstrated that skeletal anchorage enabled the correction of the maxillomandibular discrepancy, with an improvement in facial appearance and occlusion and with no dental effects. Pterygomaxillary separation was not effective, showing no superior orthopedic response on maxillary advancement or restrictions to maxillary growth in the 12-month post-treatment follow-up.

Biomechanical comparison of two intraoperative mobilization techniques for maxillary distraction osteogenesis: Down-fracture versus non-down-fracture

Purposes:

The purpose of this study was to compare the distraction forces and the biomechanical effects between two different intraoperative surgical procedures (down-fracture [DF] and non-DF [NDF]) for maxillary distraction osteogenesis.

Materials and Methods:

Eight patients were assigned into two groups according to the surgical procedure: DF, n = 6 versus NDF, n = 2. Lateral cephalograms taken preoperatively (T1), immediately after removal of the distraction device (T2), and after at least a 6 months follow-up period (T3) were analyzed. Assessment of distraction forces was performed during the distraction period. The Mann–Whitney U-test was used to compare the difference in the amount of advancement, the maximum distraction force and the amount of relapse.

Results:

Although a significantly greater amount of maxillary movement was observed in the DF group (median 9.5 mm; minimum-maximum 7.9-14.1 mm) than in the NDF group (median 5.9 mm; minimum-maximum 4.4-7.6 mm), significantly lower maximum distraction forces were observed in the DF (median 16.4 N; minimum-maximum 15.1-24.6 N) than in the NDF (median 32.9 N; minimum-maximum 27.6-38.2 N) group. A significantly greater amount of dental anchorage loss was observed in the NDF group. Moreover, the amount of relapse observed in the NDF group was approximately 3.5 times greater than in the DF group.

Conclusions:

In this study, it seemed that, the use of the NDF procedure resulted in lower levels of maxillary mobility at the time of the maxillary distraction, consequently requiring greater amounts of force to advance the maxillary bone. Moreover, it also resulted in a reduced amount of maxillary movement, a greater amount of dental anchorage loss and poor treatment stability.

The role of distraction osteogenesis in the management of craniofacial syndromes

Distraction osteogenesis (DO) has been established as a useful technique in the correction of skeletal anomalies of the long bones for several decades. However, the use of DO in the management of craniofacial deformities has been evolving over the past 20 years, with initial experience in the mandible, followed by the mid-face and subsequently, the cranium. This review aims to provide an overview of the current role of DO in the treatment of patients with craniofacial anomalies.

Long-term skeletal stability after maxillary advancement with distraction osteogenesis in cleft lip and palate patients

OBJECTIVE

To systematically review the long-term skeletal stability after maxillary advancement with distraction osteogenesis (DO) in cleft lip and palate (CLP) patients.

MATERIALS AND METHODS

Electronic databases, grey literature, and reference list searches were conducted. The inclusion criteria were stability of maxillary advancement with distraction osteogenesis assessed at the posttreatment follow-up ≥ 1 year in CLP patients. Full articles were retrieved from abstracts or titles that appear to meet the inclusion criteria or lacked sufficient detail for immediate exclusion. Once full articles were collected, they were again reviewed considering more detailed inclusion criteria for a final selection decision. A methodologic quality assessment tool was utilized.

RESULTS

Thirty abstracts/titles met the initial search criteria, and 13 articles were finally selected. Overall, methodologic quality scores were high in only one randomized clinical trial. After maxillary advancement with DO in CLP patients, the long-term horizontal relapse in A-point was less than 15% in eight studies and between 20% and 25% in four studies. The study that was judged as a high-quality study reported 8.2% horizontal relapse in A-point. The relapse rate was higher in DO with external distracter device than DO with internal distracter device.

CONCLUSIONS

Current evidence suggests maxillary advancement with DO has good stability in CLP patients with moderate and severe maxillary hypoplasia.

Limitations of internal distraction devices in mature patients with cleft lip and palate and severe midface hypoplasia

PURPOSE

We evaluated case-sensitive limitations of internal distraction devices (IDDs) to reveal further options for satisfactory outcomes.

PATIENTS AND METHODS

Two male cleft patients aged 22 years (P1) and 20 years (P2) with severe maxillary hypoplasia were treated over 18 months. Cephalometric analyses and analyses of A-point movements by superimposing lateral cephalograms were done before and after activation of IDDs and after bimaxillary surgery (BIMAX).

RESULTS

After activating IDDs, the vectors deviated and clockwise rotation of the maxilla and vectors occurred. After 8 months, BIMAX was needed to carry out further maxillary advancement.

CONCLUSIONS

IDDs could pave the way to achieve maximal advancement with BIMAX in a second step and justify the overall treatment when comparing the initial situation with outcome.

Alveolar crest regeneration using curvilinear dentoalveolar distraction osteogenesis: a preliminary study

OBJECTIVE

The objective of this study was to reconstruct alveolar crest at home position using distraction osteogenesis (DO) with a personalized curvilinear distractor designed through computer-aided technology.

STUDY DESIGN

Five adult dogs were recruited and the maxillary alveolar bone from the first incisor to the first premolar was excised. The dentoalveolar segment adjacent to the defect was osteotomized as a bone transport disk. After 8 weeks of consolidation, the dogs were humanely killed, and the regenerated bone was analyzed.

RESULTS

The DO was successful in the experimental group. The radiographs and histology both verified new bone bridging distraction gap. However, the newly formed bone was located more internally and was not in original position.

CONCLUSIONS

The proposed method to reconstruct alveolar crest at home position is improper. The key point was how to maintain the distraction space and hold it at the home position. The barrier membrane technique may be used together with DO to resolve the problem.

Stability of orthognathic surgery and distraction osteogenesis: options and alternatives

Relapse in orthognathic surgery is multifactorial and can be attributed to posttreatment growth, condylar changes, lack of rigid fixation, and muscle pull and function. Consideration of these factors can aide the surgeon in the decision-making process with regards to treatment options and alternatives. This article reviews the stability of various orthognathic movements using traditional osteotomies and fixation, and compares them to what is currently in the literature regarding distraction osteogenesis.

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.

REAL-TIME THREE-DIMENSIONAL RECONSTRUCTION FOR VOLUME-BASED SURGERY SIMULATIONS

This paper describes a three-dimensional reconstruction method to provide real-time visual responses for volume (constituted by tomographic slices) based surgery simulations. The proposed system uses dynamical data structures to record tissue triangles obtained from 3D reconstruction computation. Each tissue triangle in the structures can be modified or every structure can be deleted or allocated independently. Moreover, triangle reconstruction is optimized by only deleting or adding vertices from manipulated voxels that are classified as erosion (in which the voxels are changed from tissue to null) or generation (the voxels are changed from null to tissue). Therefore, by manipulating these structures, 3D reconstruction can be locally implemented for only manipulated voxels to achieve the highest efficiency without reconstructing tissue surfaces in the whole volume as general methods do. Three surgery simulation examples demonstrate that the proposed method can provide time-critical visual responses even under other time-consuming computations such as volume manipulations and haptic interactions.

Ultrastructural cell response to tension stress during mandibular distraction osteogenesis

The response of cells in the distraction gap during mandibular distraction osteogenesis was recorded by transmission electronic microscopy. We distracted the mandible on both sides in eight adult goats. Two animals were killed at 8, 16, 32, and 48 days, respectively, after activation of the device. The specimens were harvested and processed for histological and ultrastructural examination. The results showed that the cells and newly-formed extracellular matrix (ECM) were aligned with the tension vector. In the early stage of distraction osteogenesis, cells in the distraction gap were of the active proliferative phenotype. They then differentiated into fibroblast-like cells and osteoblasts, showing ultrastructural characteristics of the active synthetic and secretory phenotypes. Newly-formed collagen, bone canaliculi, and mineralisation of the ECM were clearly evident during distraction osteogenesis. Our results show that at the ultrastructural level cell proliferation is activated by tension and stress during the early stages, and synthetic and secretory function stimulated during the later stages of mandibular distraction osteogenesis.