Differences in mandibular distraction osteogenesis after corticotomy and osteotomy

Comparison of rate of maxillary canine movement with or without modified corticotomy facilitated orthodontic treatment: A prospective clinical trial

Background and Objectives

The average orthodontic treatment time for extraction therapy is 31 months. One of the main disadvantages of orthodontic treatment is time. Alveolar corticotomies have been used in conjunction with orthodontics to reduce the treatment time by increasing the rate of tooth movement. Concerns about the possible risks of corticotomy procedure have led to the modification of this technique. Germeç et al. reported a case treated by their modified corticotomy technique and noted reduced treatment time without any adverse effects on the periodontium and the vitality of teeth with their new conservative corticotomy technique. This study was undertaken to clinically evaluate the efficacy of the aforesaid technique.

Materials and Methods

A split-mouth study design was carried out to compare the rate of maxillary canine movement with and without modified corticotomy facilitated orthodontic treatment in 10 patients requiring maxillary first premolar extractions. The modified corticotomy procedure was performed on the maxillary arch unilaterally. The upper arch was immediately activated bilaterally after surgical procedure using equal orthodontic forces for retraction of the maxillary canines. The amount of tooth movement was recorded at an interval of every month till the completion of canine retraction. The rate of canine movement on experimental and control site was compared. The patients were followed for 6 months to check the occurrence of undesired effects such as root resorption, periodontal damage and loss of vitality of teeth on the experimental side.

Results

Higher mean velocity was observed in canines with modified corticotomy facilitated retraction compared to conventionally retracted canines; with the difference in mean velocity between the two groups was found to be clinically significant as well as statistically significant (P < 0.001).

Interpretation and Conclusion

The results suggested that modified corticotomy technique serves as an effective and safe way to accelerate orthodontic tooth movement, without adversely affecting the periodontium, root resorption, and the vitality of the teeth, as concluded by clinical and radiographic examination.

The effect of heparan sulfate application on bone formation during distraction osteogenesis

Bone morphogenetic proteins (BMPs) are recognized for their ability to induce bone formation in vivo and in vitro. Their osteogenic and osteoinductive properties are tightly regulated by the secretion of specific BMP antagonists, which have been shown to physically bind and sometimes be blocked by the extracellular proteoglycan heparan sulphate side chains (from hereon referred to as HS). The purpose of this study was to investigate if local application of 5 µg of HS proteoglycan to a bone regenerate site in a mouse model of distraction osteogenesis (DO) can accelerate bone healing and affect the expression of key members of the BMP signaling pathway. DO was performed on the right tibia of 115 adult male wild-type mice. At mid-distraction (day 11), half the group was injected locally with 5 µg of HS, while the other half was injected with saline. The mice were sacrificed at 2 time-points: mid-consolidation (34 days) and full consolidation (51 days). The distracted tibial zone was then collected for analysis by μCT, radiology, biomechanical testing, immunohistochemistry, and histology. While μCT data showed no statistically significant difference in bone formation, the results of biomechanical testing in stiffness and ultimate force were significantly lower in the HS-injected bones at 51 days, compared to controls. Immunohistochemistry results also suggested a decrease in expression of several key members of the BMP signaling pathway at 34 days. Furthermore, wound dehiscence and infection rates were significantly elevated in the HS group compared to the controls, which resulted in a higher rate of euthanasia in the treatment group. Our findings demonstrate that exogenous application of 5 µg of HS in the distracted gap of a murine model had a negative impact on bone and wound healing.

Treatment of Class II open bite complicated by an ankylosed maxillary central incisor

Ankylosed teeth in growing patients cause troublesome dentoalveolar problems and require special therapeutic care for accomplishing long-term esthetic and functional results. The various treatment modalities for ankylosed teeth include reconstruction after extraction, surgical extrusive luxation, individual segmental osteotomy or corticotomy, and alveolar distraction osteogenesis. This report describes a case of a 13-year-old boy with anterior open bite complicated by an ankylosed maxillary central incisor that was managed by corticotomy-facilitated orthodontic treatment.

The design and use of animal models for translational research in bone tissue engineering and regenerative medicine

This review provides an overview of animal models for the evaluation, comparison, and systematic optimization of tissue engineering and regenerative medicine strategies related to bone tissue. This review includes an overview of major factors that influence the rational design and selection of an animal model. A comparison is provided of the 10 mammalian species that are most commonly used in bone research, and existing guidelines and standards are discussed. This review also identifies gaps in the availability of animal models: (1) the need for assessment of the predictive value of preclinical models for relative clinical efficacy, (2) the need for models that more effectively mimic the wound healing environment and mass transport conditions in the most challenging clinical settings (e.g., bone repair involving large bone and soft tissue defects and sites of prior surgery), and (3) the need for models that allow more effective measurement and detection of cell trafficking events and ultimate cell fate during the processes of bone modeling, remodeling, and regeneration. The ongoing need for both continued innovation and refinement in animal model systems, and the need and value of more effective standardization are reinforced.

Are endogenous BMPs necessary for bone healing during distraction osteogenesis?

Previous reports suggest the application of exogenous BMPs can accelerate bone formation during distraction osteogenesis (DO). However, there are drawbacks associated with the use of exogenous BMPs. A possible alternative to the use of exogenous BMPs is to upregulate the expression of endogenous BMPs. Since DO results in spontaneously generated de novo bone formation in a uniform radiographic, histological, and biomechanical temporal sequence, a genetically engineered model lacking endogenous BMP2 should have measurable deficits in bone formation at different time points. We performed DO on BMP2(fl/+) and BMP2(fl/+ cre) mice using a miniature Ilizarov fixator. Distracted samples were collected at various time points and analyzed using real time-quantitative PCR, lCT, radiology, immunohistochemistry, histology, and biomechanical testing. Immunohistochemical studies of 34-day heterozygous samples showed reduced expression of BMP2, BMP7, BMPR1a, ACTR1, and ACTR2b. lCT analysis of 51-day heterozygous samples revealed a decrease in trabecular number and increase in trabecular separation. Biomechanical testing of 51-day heterozygous samples revealed decreased stiffness and increased ultimate displacement. Radiological analysis showed the heterozygotes contained a decreased bone fill score at 17, 34, and 51 days. These data suggest endogenous BMPs are important for bone healing and manipulating endogenous BMPs may help accelerate bone consolidation during DO.

RFD. Avaliação da densitometria óssea de tecido ósseo neoformado após distração osteogênica mandibular

OBJETIVO: avaliar radiograficamente a qualidade óssea no local da distração osteogênica. METODOLOGIA: vinte ratos foram divididos em 2 grupos: Distração Osteogênica (DO) e Controle (C). Os animais do grupo DO foram submetidos à osteotomia da mandíbula, fixação de um aparelho distrator e aplicação de força de distração osteogênica. Os animais do grupo C serviram como controle para a avaliação do tecido ósseo produzido pela técnica da distração osteogênica. As mandíbulas desses animais foram segmentadas transversalmente, tiveram seus segmentos separados em 2,5mm de forma aguda no ato cirúrgico e fixados nessa posição. Nos 2 grupos, os animais foram sacrificados com 2 e 6 semanas após o término da DO (5 animais em cada período). As mandíbulas foram radiografadas simultaneamente, sobre o mesmo filme radiográfico. As imagens obtidas foram digitalizadas e submetidas à análise de densitometria óssea. RESULTADOS E CONCLUSÕES: os grupos DO e C não apresentaram diferenças estatísticas na neoformação óssea nos períodos analisados. As mandíbulas dos dois grupos apresentaram consolidação incompleta na segunda semana e consolidação completa 6 semanas após a distração osteogênica e estabilização. As diferenças encontradas entre esses dois períodos foram significativas apenas para o grupo DO.

Osteogenic alveolar distraction: A review of the literature

OBJECTIVE

Alveolar distraction is a relatively novel procedure by which alveolar bone and underlying mucosa are regenerated. The low predictability of other vertical or horizontal bone regeneration methods has increased interest in this promising technique. This article was designed to review published clinical and experimental results on alveolar distraction, including basic research in other disciplines (maxillofacial and orthopedic distraction) related to or with influence on alveolar distraction.

STUDY DESIGN

A review of the international literature was performed to summarize results of clinical and experimental studies on alveolar distraction and on distraction at other anatomical sites that contribute important findings on tissue biology, molecular mechanisms, and other factors that influence and participate in the alveolar distraction process.

RESULTS

Research into alveolar distraction has addressed the latency phase, distraction phase, and consolidation phase, yielding highly variable results. Little experimental research has been carried out on this procedure, and most publications are clinical studies with a short follow-up period. Published studies have reported a high rate of complications, attributable to our current lack of understanding of the process.

CONCLUSIONS

Definitive conclusions on alveolar distraction are hampered by the lack of clinical and experimental studies to date. Greater knowledge of the factors that influence the distraction process will lead to a more predictable and efficacious distraction technique and a better distractor design.

Temporospatial expression of vascular endothelial growth factor and basic fibroblast growth factor during mandibular distraction osteogenesis

OBJECTIVE

Distraction osteogenesis is a vascular-dependent process. This study investigated expression patterns of two major angiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), in the distracted calluses following mandibular lengthening in a goat model.

MATERIAL AND METHODS

Bilateral mandibular osteotomies were performed in 15 young adult goats. After a latency of 7 days, the mandibles were elongated using custom-made distractors with a rate of 1 mm/day for 10 days. Three animals each were sacrificed at the end of the delay phase, at 0, 7, 14, and 28 days after completion of distraction, respectively. The lengthened mandibles were harvested and processed for histological and immunohistochemical examinations.

RESULTS

Elevated cellular expression of VEGF and bFGF, with neovascularization in the distraction gap, was observed following mandibular lengthening. VEGF staining was noted in the endothelial cells and osteoblasts. bFGF staining was seen in the fibroblast-like cells, osteoblasts and immature osteocytes. Their strongest expression was found 0-7 days after the end of distraction, and declined with maturation of the newly formed bone.

CONCLUSION

A temporal and spatial expression pattern of VEGF and bFGF was found during distraction osteogenesis in goat mandibles. It suggests that distraction forces can stimulate the production of VEGF and bFGF, which contribute to neovascularization and new bone formation during gradual distraction of the mandible. Application of angiogenic factors may be considered as a potential method to enhance angiogenesis and osteogenesis in osteodistraction, especially in sites without enough vascularization.