Healing process after alveolar ridge distraction in sheep

Does the Animal Model Influence in Vertical Alveolar Distraction? A Systematic Review of the Literature

Simple Summary

Vertical alveolar osteogenesis distraction (VAOD) technique appears to provide the best results in terms of vertical bone gain. Before its use in humans, most devices are tested on experimental animals. Currently, there is no consensus on which is the ideal biological animal model for VAOD studies. In this review, it has been found that the animal model influences the results. In addition, the most used, easier to handle, and with less complications was the Mongrel dog. The use of pigs and minipigs, given their difficult handling and poor hygiene, is not recommended.

Abstract

This study is aimed at synthesizing all available evidence on vertical alveolar osteogenesis distraction (VAOD) in animal trials to determine whether the animal model used and its handling influence or not, and find which is the most appropriate animal model for this specific technique. This systematic review has been carried out following the PRISMA statements. Bibliographic sources have been consulted manually by two reviewers. Risk of bias was assessed using a version of the Newcastle-Ottawa-Scale (NOS). The selection criteria established by expert researchers were applied in order to decide which studies should be included in the review. Twenty-six studies met the inclusion criteria and were included in the review. Twenty-four of them had a high quality (score between 7 and 9), two medium quality (score between 4 and 6), and none low quality (score between 1 and 3). The highest possible score was 9 (using the NOS). Six studies complied with all NOS criteria. The animal model has been seen to influence the results, leading to failure in some cases. The most used animal model on VAOD, with fewer complications, was the Mongrel dog. The use of the pig and minipig is not recommended, due to the difficulties in handling and complications encountered.

Publication Trends in Craniofacial Distraction: A Bibliometrical Analysis

PURPOSE

The purpose of this study was to analyze the craniofacial distraction literature published over the last 50 years and to determine various trends in publications.

METHODS

A literature search was conducted in November and December 2015. The date search range was 1965 to 2015. Databases searched included Medline, Web of Science, Biosis, SciELO, Data Citation, and Zoologic Records. Data were collected on distraction type, author specialty, date of publication, country, state (if United States), number of citations, journal name, journal type, and Le Fort type (for midfacial distractions).

RESULTS

Total number of craniofacial distraction publications was 1729. Cranial distraction accounted for (11%), midfacial (11%), and mandibular (78%). Largest increase in publications was in the 1990s, with 48 publications from 1991 to 1995 rising to 261 publications from 1996 to 2000. Among the cranial distraction publications, Plastic and Reconstructive Surgery (PRS) (67%) were the most frequent authors but among the midfacial and mandibular distraction publications, Oral and Maxillofacial Surgery (OMFS) were the most frequent authors (68% and 64%, respectively). Total number of citations was 26,281 with OMFS (50.4%) and PRS (37%) being cited most frequently. Oral and Maxillofacial Surgery was cited most for mandibular and midfacial distraction, and PRS was cited most for cranial distraction.

CONCLUSION

Research on craniofacial distraction has significantly increased since the 1970s, with mandibular distraction accounting for the majority of this rise. Among specialties, OMFS and PRS account for the majority of the literature. The United States leads the publication. Authors tend to publish distraction literature in their corresponding journal specialty, with the exception of PRS who publishes most frequently in OMFS journals.

Partially Biodegradable Distraction Implant to Replace Conventional Implants in Alveolar Bone of Insufficient Height: A Preliminary Study in Dogs

BACKGROUND

Dental implants have been widely used in the last few decades. However, patients with insufficient bone height need reconstructive surgeries before implant insertion. The distraction implant (DI) has been invented to simplify the treatment procedure, but the shortcomings of DIs have limited their clinical use. We incorporated biodegradable polyester into a novel DI called the partially biodegradable distraction implant (PBDI).

PURPOSE

The purpose of this study was to assess the radiological, histological, and biomechanical properties of the PBDI in animal models.

MATERIAL AND METHODS

PBDIs were manufactured and inserted into the atrophied mandibles of nine dogs. Box-shaped alveolar bones were segmented and distracted. The dogs were randomly divided into three groups that were sacrificed 1, 2, and 3 months after the implant insertion. Actual augmentation height (AAH) of the bone segments was measured to evaluate the effect of distraction. X-ray examination and micro-CT reconstruction and analysis were used to evaluate the regenerated bone in the distraction gap and bone around the functional element. Histological sections were used to evaluate the osseointegration and absorption of the PBDI. Fatigue tests were used to evaluate the biomechanical properties of the PBDI.

RESULTS

Little change was found in AAH among the three groups. X-ray examination and micro-CT reconstruction showed good growth of regenerated bone in the distraction gap. Alveolar bone volume around the functional element increased steadily. No obvious bone absorption occurred in the alveolar crest around PBDI. Three months after distraction, the functional element achieved osseointegration, and the support element began to be absorbed. All PBDIs survived the fatigue test.

CONCLUSIONS

The PBDI is a novel and reliable dental implant. It becomes a conventional implant after the absorption of the support element and the removal of the distraction screw. It is a promising replacement for conventional implants in patients with insufficient alveolar bone height.

Evaluation of Vertical Bone Gain Following Alveolar Distraction Osteogenesis in the Anterior Edentulous Mandible: A Clinical Study

AIM AND OBJECTIVES

To calculate the gain in bony height and volume of the distracted upper segment using an extraosseous unidirectional device to improve the retention of the future prosthesis.

MATERIALS AND METHODS

Ten cases with completely or partially edentulous but severely or considerably resorbed anterior mandibles were managed by vertical alveolar distraction osteogenesis. All the patients were evaluated preoperatively, intraoperatively and post-operatively for various parameters clinically and radiographically i.e. on OPG, lateral cephalogram and on CT scan, at different time intervals. In all cases there was increase in vertical bone height.

RESULTS

The study showed mean vertical bone gain (VBG) on OPG as 8.2 mm. The mean VBG on lateral cephalogram was 8.1 mm. The mean VBG on CT scan at right canine was 8.35 mm, at left canine was 8.2 mm and at midline was 8.27 mm.

CONCLUSION

Alveolar distraction osteogenesis is a predictable method for restoring alveolar ridges prior to implant placement or prosthesis. Distraction osteogenesis is ideally suited for recreating missing tissue in the anterior esthetic zone by increasing vertical bone height as well as good width and soft tissue growth.

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.

Endosseous alveolar distractor (LEAD™) in the management of residual alveolar ridge resorption

BACKGROUND

Lack of sufficient alveolar bone height or width is one of the most frequent problems in the dental rehabilitation of the edentulous patient.

METHODS

A prospective study to evaluate the efficacy of an endosseous alveolar distractor (LEADTM) in managing residual alveolar ridge resorption was carried out. The complications related to the surgical procedure and the quantitative changes in the regenerate over a 6 month period following distraction were studied in 13 cases with alveolar ridge atrophy.

RESULT

Desired ridge augmentation was achieved in 11 cases. In 2 cases the distraction failed. Some unusual complications were encountered.

CONCLUSION

The LEAD™ alveolar distractor produces consistent augmentation of the alveolar bone but is confronted with stability issues.

Animal experimental study on repairing alveolar clefts by using rectilinear distraction osteogenesis

The aim of this study was to evaluate the clinical applicability of rectilinear distraction osteogenesis for repairing alveolar cleft models. Alveolar process distraction surgery to produce bilateral clefts was performed on six adult cats. In our study, the left side with the distraction device was the experimental side, and the other side without a distraction device was the control side. After a 6-day latent period, animals underwent gradual distraction at a rate of 0.6mm per day (distraction was performed twice each day, at a rate of 0.3mm each time), until the tissue on the two sides of the cleft touched, then the distraction strength was maintained for 2 days. Two cats were sacrificed at 2 weeks, 6 weeks and 10 weeks postoperatively. Gross anatomical, histological and radiographical analyses were performed after the animals were sacrificed. In addition, the arch width was measured both before setting the distraction device and after distraction was complete. Two weeks after the distraction was complete, the soft tissue of the two sides of the cleft region on the experimental side touched, and it began to coalesce. The extremities of the two sides of the cleft region on all the experimental sides drew close to each other, but there was no bony conjunction. New bone formation appeared in the distraction region. The arch width at the front of the maxillary bone on the distraction side after distraction was smaller than before distraction. The alveolar cleft could be closed by rectilinear distraction osteogenesis. Two sides of the cleft touched each other and only soft tissue coalesced, but we did not observe bone coalescing. This phenomenon suggested that it might be difficult to achieve complete bony repair by rectilinear distraction osteogenesis. However, rectilinear distraction osteogenesis can minimise the size of the alveolar cleft and make bone grafting advisable for those patients who are not suitable for bone grafting before distraction osteogenesis.

Recommendations for optimal distraction protocols for various animal models on the basis of a systematic review of the literature

The principles of orthopaedic distraction osteogenesis (DO) have been successfully applied to the craniofacial skeleton, but the latency time, rate and rhythm of distraction, and length of the consolidation period that are optimal for long-bone distraction may be suboptimal for craniofacial DO. The aim of this study was to provide recommendations for optimal distraction parameters in animal experimental research on craniofacial DO. The data used were from studies, added to the PubMed database between 1 January 1973 and 1 January 2007, on the outcome of DO resulting from variations in a single distraction parameter while standardizing the other distraction parameters. Although experimental animal group sizes were rather small, especially in those studies that used large animals, and both skeletally mature and immature animals were used, the (in most cases quantitative) data provided useful information on the optimal parameters in craniofacial DO. A latency period may not be necessary at all. Distraction should be performed at a rate of 1mm/day (this may be halved when small animals such as rats are used) preferably with a continuous rhythm, followed by a consolidation period of 6-8 weeks. These recommendations can be used as basic guidelines for further animal experimental studies on craniofacial DO.

Evaluation of Osseous Regeneration in Alveolar Distraction Osteogenesis With Histological and Radiological Aspects

PURPOSE

Alveolar distraction osteogenesis is used for reconstruction of defects caused by trauma, periodontal disease, or congenital anomalies of the dentoalveolar region.

PATIENTS AND METHODS

Alveolar distraction osteogenesis was performed on 10 patients with various vertical alveolar defects in the mandible. Panoramic radiographs and computed tomography (CT) scans were obtained preoperatively. At the end of 12 weeks, panoramic radiographs and dental CT scans were taken and the bony specimens were harvested from the distracted areas by trephine bur for histologic evaluation. After a year, the status of the distraction areas was assessed by radiographs and dental CT scans. Densities of the newly formed bone were evaluated at the twelfth week and the first year by dental CT scans.

RESULTS

At the twelfth week, tubular bone was longitudinally oriented and osteoblastic activation was increased; the osseous density in the distraction chamber was higher than the original medullary bone density, which increased from the twelfth week to the first year. The regenerated bones were more dense (866.81) than the pre-existing medullary bone (309.66), and less dense than the pre-existing cortical bone (1641.12) at the twelfth week. Bone densities were seen to have increased gradually by the end of the first year (1089.99).

CONCLUSION

Alveolar distraction osteogenesis can be used successfully for reconstruction of alveolar bone deficiencies caused by trauma or periodontal defects.

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.

Horizontal distraction of the anterior maxilla in combination with bilateral sinuslift operation--preliminary report

In many cases alveolar ridge atrophy causes severe alveolar ridge deficiency in horizontal and vertical direction. In cases of severe atrophy of the edentulous maxilla a maxillary retrognathism results. In this article, a new technique of solving this problem prior to implant placement is described. In six patients with severe atrophy of the edentulous maxilla a sinuslift operation and placement of dental implants were carried out in the posterior maxilla. In the anterior part of the maxilla a segmental split osteotomy and placement of two miniplate distractors were performed. One week after surgery distraction started with a distraction speed of 0.5 mm a day until a clinical correct position of the anterior maxilla resulted. Then, the stabilisation period of 12 weeks followed before the distractors were removed and two to four implants were placed in the anterior distracted maxilla. After a second healing period of 4 months the implants were used for loading by a fixed prosthetic superstructure. Six patients were treated by this regime and 58 implants were placed. All implants were loaded by a fixed prosthesis. Distraction was performed without disturbances. Three months after healing new bone was formed in the distraction gap. There was no implant loss. An aesthetic satisfying superstructure with good red and white aesthetics was achieved together with a correct interalveolar relation. Distraction of the anterior part of the maxilla in combination with sinuslift operation is an alternative technique for correction of interalveolar incongruences in the edentulous maxilla and augmentation prior to implant placement.

Evaluation of minipigs as an animal model for alveolar distraction

OBJECTIVE

Alveolar distraction osteogenesis is a relatively novel tissue regeneration technique that remains, in some respects, at an experimental stage. The selection of an experimental animal biomodel is not clearly defined, with reports in the reviewed literature on dogs, sheep, and monkeys. The present objective was to compare 2 experimental biomodels (dog and minipig) using an alveolar distraction protocol with a novel prototype distractor.

STUDY DESIGN

Three beagle dogs and 3 Göttingen minipigs were evaluated, placing the distractor at the right hemimandible alveolar ridge after previous extraction of premolars. The radiological examination was carried out immediately after the distraction and at 2 weeks of consolidation.

RESULTS

Satisfactory clinical and radiological results were obtained in 2 of 3 beagle dogs after the previous unilateral extraction of mandibular and maxillary premolars. During the consolidation, a height gain of approximately 5 mm was observed, with the appearance of radiodense bone trabeculae in the distraction chamber. The distraction failed in all of the minipigs.

CONCLUSION

The minipig was not an appropriate biomodel for the study of alveolar distraction because the investigators were not able to maintain the seal of the distraction chamber or the stability of the distractor.

Horizontal alveolar distraction of the narrow maxillary ridge for implant placement

PURPOSE

The purpose of this report was to describe a surgical technique for performing horizontal alveolar distraction of the knife-edge maxillary ridge.

PATIENT AND METHODS

The patient was a 17-year-old woman with atrophy of the alveolar rim in the anterior upper jaw, which had inadequate width for implant placement. The transport segment was constructed by the osteotomy of the labial cortex of the alveolus. A transport plate of a distractor (LEAD system; Stryker Leibinger, Kalamazoo, MI) was placed on the transport segment. The distraction rod was inserted horizontally, and put in contact with the palatal cortex at the top. A base plate was not placed.

RESULTS

The alveolar distraction was successfully performed to gain 6.0 mm in width and 0.5 mm in height, allowing placement of three 14-mm implants. All the implants were integrated so as to support the prosthesis.

CONCLUSIONS

Alveolar distraction can be useful for augmenting the narrow ridge horizontally and placement of implants.

Vertical alveolar bone distraction at molar region using lag screw principle

PURPOSE

Recently, alveolar bone distraction has been widely used and several devices have been developed for this purpose. However, there are some disadvantages in each device, especially for distraction of posterior alveolar ridge. The purpose of this study was to develop a new device for vertical alveolar bone distraction at the molar region and to show the results of its clinical application.

MATERIALS AND METHODS

The mechanism of device is based on lag screw principle and the device consists of the following 4 components; distraction screw, hole implant fixture, supporting plate, and temporary short implant and/or neighboring natural teeth. The distraction screw suspended at the supporting plate is inserted into the internal thread of the hole implant fixture placed at alveolar transport segment. If the distraction screw turns at the supporting plate, the hole implant fixture with transport segment moves to the supporting plate without vertical movement of the screw at the supporting plate like a lag screw. After an animal experiment using 4 beagle dogs, the device was clinically applied in 4 patients before implant insertion.

RESULTS

The distraction of the alveolar bone could be successfully performed in all patients without any complications. The direction of distraction with this device could be adjustable, and the alveolar bone could be distracted not only vertically but also horizontally. Moreover, the surgical technique is simple with no need for a second surgery, and there is no occlusal disturbance from the device.

CONCLUSIONS

The new device for alveolar bone distraction using lag screw principle can be used effectively in the molar region.

Distraction Osteogenesis for Augmenting the Deficient Alveolar Ridge in Preparation for Dental Implant Placement: A Case Report

Distraction osteogenesis is a process in which new bone is created in a defect of the alveolar ridge by stretching existing bone. The process was originally developed by a Russian orthopedist, Gavriel Ilizarov, for the correction of long-bone deformities. It was later adapted to the maxillofacial skeleton and alveolar ridge. Distraction osteogenesis involves surgically creating a mobile bone segment to which a distraction device is attached. By controlled movement, the bone segment, along with the soft tissues overlying it, are transported into a new position. After a suitable healing period, the distraction device is removed and dental implants can be placed. A case report is presented describing the use of alveolar distraction to augment a vertically deficient alveolar ridge.

Cranio-facial distraction osteogenesis: a review of the literature. Part II: Experimental studies

In this study the literature dealing with experimental cranio-facial distraction osteogenesis (DO) was reviewed. A PUBMED search (National Library of Medicine [NCBI] revised 1 April 2001) from 1966 through December 2000 was conducted. Key words used in the search were: distraction, lengthening, mandible, mandibular, maxilla, maxillary, midface, midfacial, monobloc, cranial, cranio-facial, maxillofacial. This search revealed a total of 120 experiment-orientated articles that were all analyzed in detail in this study. The purpose of the experimental study, animal model, animal growth status, type of distraction, type of surgery, distraction rate and rhythm, latency and contention period, amount of lengthening, relapse, complications and nature of the distraction device were analyzed. This review revealed that a total of 1207 animals were used in seven different animal models for research on cranio-facial DO: 54 using dogs (45.0%), 25 using rabbits (20.8%), 18 using sheep (15.0%), 11 using minipig (9.2%), seven using monkeys (5.8%), four using rats (3.3%) and one using a cat model (0.8%). Based on the results of this study, an attempt was made to provide biological DO parameters and guidelines for future research on experimental cranio-facial DO related to the appropriate animal model.

Immediate alveolar ridge distraction after tooth extraction--a preliminary report

Seven patients with severe periodontitis that had resulted in loss of alveolar ridge bone were treated by tooth extraction followed by immediate insertion of an implant distraction device. After successful distraction and bony healing the implant was used to fit a prosthesis.

[Distraction osteogenesis for the premaxillary reconstruction. Report of 3 cases]

Reconstructing the premaxillary is well-known for being difficult and usually requires a bone implant, in grafts or flaps. This technique has a high morbidity rate and its middle or long term results remain uncertain. Thanks to their experience and to the results they achieved in mandible and maxillary osteogenic distraction, the authors suggest applying the principle of distraction osteogenesis to the premaxillary reconstruction. Three patients have been treated: first, two hypoplasias of the premaxillary, sequelae of a cleft palate and of a former traumatic loss of teeth; secondly one premaxillary defect following a gunshot wound. The first two were women, the other one was man, all adults. For premaxillary distraction, an intraoral extramucosa device is made-up for each individual case before the surgical operation itself and after an orthognathic analysis. The surgical operation consists in a classical segmental maxillary osteotomy which respects the palatal periosteum, and also in fitting a distractor device with transmucosa screws into the palatal bone. In each of the three cases, with a follow-up from 24 to four months, the reconstruction of the premaxillary by distraction osteogenesis is considered satisfactory and stable as regards both bone and soft tissues. This achieves particularly a very good expansion of the fibrous mucosa of the palate which makes it possible to re-insert false teeth, with or without implants into the bone. The principle of distraction osteogenesis applied to premaxillary reconstruction has shown, in our cases, very good functional and aesthetic results. Yet the techniques we used are simple and have a low morbidity rate; secondly the distraction device is easy to design and little expansive.