Healing of the displaced condylar process fracture: an experimental study

Taking the endochondral route to craniomaxillofacial bone regeneration: A logical approach?

The current golden standard for treatment of craniomaxillofacial critical size bone defects, autologous bone grafting, is associated with several disadvantages which have prompted an increased demand for alternatives. New solutions are emerging in the form of bone tissue engineering. This involves harvesting of multipotent mesenchymal stromal cells (MSCs), after which they can be differentiated towards the osteogenic lineage mimicking intramembranous bone formation. However, translating this approach from laboratory to clinic has met with limited success. Consequently, attention has shifted towards investigation of the alternative endochondral route of bone regeneration. At a first glance, this approach may not appear logical for maxillofacial bone regeneration as most bones in the face originate from intramembranous mechanisms. Therefore, the goal of this review is to discuss the sense and non-sense of exploring endochondral bone regeneration as a novel reconstructive option for craniomaxillofacial bone defects. The embryological origin of craniomaxillofacial bone structures and their repair mechanisms are introduced. Also, the potential of MSC-like cells, the neural crest-derived stem cells from craniomaxillofacial sources, are discussed with a focus on regeneration of bone defects. Further, the current status of endochondral bone regeneration from MSCs is highlighted. Together, these aspects contribute in answering whether endochondral bone regeneration can be a logical approach to restore craniomaxillofacial bone defects.

Facial symmetry evaluation after experimentally displaced condylar process fracture in methotrexate treated rats

PURPOSE: To investigate the facial symmetry of high and low dose methotrexate (MTX) treated rats submitted to experimentally displaced mandibular condyle fracture through the recording of cephalometric measurements. METHODS: One hundred male Wistar rats underwent surgery using an experimental model of right condylar fracture. Animals were divided into four groups: A - saline solution (1mL/week); B - dexamethasone (DEX) (0,15mg/Kg); C - MTX low dose (3 mg/Kg/week); D - MTX high dose (30 mg/Kg). Animals were sacrificed at 1, 7, 15, 30 and 90 days postoperatively (n=5). Body weight was recorded. Specimens were submitted to axial radiographic incidence, and cephalometric mensurations were made using a computer system. Linear measurements of skull and mandible, as well as angular measurements of mandibular deviation were taken. Data were subjected to statistical analyses among the groups, periods of sacrifice and between the sides in each group (α=0.05). RESULTS: Animals regained body weight over time, except in group D. There was reduction in the mandibular length and also changes in the maxilla as well as progressive deviation in the mandible in relation to the skull basis in group D. CONCLUSION: Treatment with high dose methotrexate had deleterious effect on facial symmetry of rats submitted to experimentally displaced condylar process fracture.

Effects of the condylar process fracture on facial symmetry in rats submitted to protein undernutrition

PURPOSE: To investigate the facial symmetry of rats submitted to experimental mandibular condyle fracture and with protein undernutrition (8% of protein) by means of cephalometric measurements. METHODS: Forty-five adult Wistar rats were distributed in three groups: fracture group, submitted to condylar fracture with no changes in diet; undernourished fracture group, submitted to hypoproteic diet and condylar fracture; undernourished group, kept until the end of experiment, without condylar fracture. Displaced fractures of the right condyle were induced under general anesthesia. The specimens were submitted to axial radiographic incidence, and cephalometric mensurations were made using a computer system. The values obtained were subjected to statistical analyses among the groups and between the sides in each group. RESULTS: There was significative decrease of the values of serum proteins and albumin in the undernourished fracture group. There was deviation of the median line of the mandible relative to the median line of the maxilla, significative to undernutrition fracture group, as well as asymmetry of the maxilla and mandible, in special in the final period of experiment. CONCLUSION: The mandibular condyle fracture in rats with proteic undernutrition induced an asymmetry of the mandible, also leading to consequences in the maxilla.

Pathological changes after the surgical creation of a vertical intracapsular condylar fracture

The aim of this study was to create in a sheep model an intracapsular oblique vertical split fracture, and observe the histopathological changes in the temporomandibular joint (TMJ) condylar head. In 10 sheep, the right TMJ was operated through the preauricular region. The anterior and posterior attachments of the disc were cut; an oblique vertical osteotomy was made from the lateral pole of the condyle to the medial side of condylar neck. The condylar fragment was pushed anteriorly, inferiorly and medially together with the disc. The non-operated left TMJ served as control. Two sheep were killed at 1 week and four at both 4 and 12 weeks. Computed tomography scans were taken and histopathological changes of the joint observed. There was severe bone erosion and a new bony outgrowth on the lateral side of the condylar stump and temporal bone. The joint spaces were filled with fibrous tissue, cartilage tissue and bone in the 4 and 12 weeks operated groups. These results show that an oblique vertical intracapsular fracture through the lateral condylar pole, combined with an anteriorly and medially displaced condylar fragment and disc and damaged lateral capsule, are likely to result in the pathological changes of osteoarthritis, and the progressive development of ankylosis in a sheep TMJ.

A sheep model of intracapsular condylar fracture

PURPOSE

An animal model of a condylar head fracture similar to a type B intracapsular fracture in humans was created. The effect of this model on mandibular function and morphological changes of temporomandibular joint (TMJ) structure was evaluated.

MATERIALS AND METHODS

Ten sheep were divided into 3 groups, sacrificed at 1 week (2 sheep), 4 weeks (4 sheep), and 12 weeks (4 sheep) after surgery. The right side of the TMJ was considered the surgical group; the left side, the control group. The anterior and posterior attachments of the discs were cut, and an oblique vertical osteotomy was made from the lateral pole of the condyle to the medial side of the condylar neck. The condyle fragment was pushed together with the disc anteriorly, inferiorly, and medially. The lateral side of the condylar stump was sutured to the capsule to limit movement. Preoperative and postoperative body weight, maximum mouth opening, lateral excursions, and x-ray and computed tomography (CT) findings in the 3 surgical groups and the control group were recorded. The SPSS software program was used for all statistical analyses.

RESULTS

There were no significant differences in weight loss and left lateral movement among the 3 surgical groups, but maximum mouth opening and the right lateral movement decreased significantly in the 4-week and 12-week surgical groups. X-rays demonstrated severe bone erosion and new bony outgrowth in the lateral side of the condylar stump and a narrowed, indistinct joint space in these 2 groups. Three-dimensional reconstruction of CT images showed changed contours of the condylar stump, condylar fragment and articular eminence in all 3 surgical groups.

CONCLUSIONS

This study demonstrates progressive changes toward ankylosis and pathological changes in sheep TMJ over time consistent with what has been found in humans.

Reconstruction of a mandibular critical-sized defect using iliac graft in rats

OBJECTIVE

To evaluate, histologically and by optical densitometry of radiographs, the healing of a critical-sized defect in the rat mandible filled with iliac graft.

MATERIALS

The study was conducted on 25 adult Wistar rats. With the rats under general anesthesia, a bicortical critical-sized osseous defect was created in the right mandibular ramus and filled with autogenous iliac crest graft. The animals were divided into 5 groups, with 5 rats in each. They were sacrificed after 1, 7, and 14 days, and 1 and 3 months. The mandibles were removed, fixed in formalin, and radiographed. The right hemi-mandibles were decalcified, and sections were cut and stained with hematoxylin and eosin.

RESULTS

Initially, an acute inflammatory process was noted along the graft that was tightly fitted to the defect. Subsequently, intense bone neoformation from external corticals and in the inner spaces of the graft was observed, while medullar spaces were occupied by granulation tissue and osteoblasts. There was remodelation of the receptor site, with a decrease in the graft volume and medullary space, as well as cancellous bone replaced by compact bone. Later, the receptor site was similar to the normal mandible, and only devitalized remnants of corticals of the graft were found. Optical densitometry of radiographs revealed statistically significant differences between experimental and control sites.

CONCLUSIONS

This experimental model is valuable in the study of bone healing. The study showed that autogenous iliac graft promoted healing of the critical-sized defect of the mandible with complete bony remodeling.

Skeletal changes after experimentally displaced condylar process fracture in growing rats

INTRODUCTION

Fractures of the mandibular condyle are common. A potential for growth disturbances in young individuals has been reported; however, there are few experiments studying such consequences. Skeletal changes after fracture of the condyle in the growing period were analysed in this study.

MATERIAL

Fifty young Wistar rats weighing 100g were used. Under general anaesthesia unilateral fracture dislocations of the condylar process were induced surgically in the experimental group (n=25), while only surgical access was performed in the sham-operated group. The animals were sacrificed at 3 months of age. The mandibles were disarticulated, and radiographs were taken (axial skulls and lateral hemimandibles). Cephalometric evaluations were made using a computer system. Statistical tests were applied between groups and contralateral sides in each group.

RESULTS

There were atrophy and degenerative change of the fractured condylar process. There was also a significant difference in the height of the mandibular body and in the length of anterior and posterior maxilla.

CONCLUSION

It was concluded that an experimental fracture of the mandibular condyle during the growing period in rats induced degenerative changes of the condyle as well as an asymmetry of the mandible, affecting height of the body, also leading to consequences in the maxilla.

A comparative study of unilateral dislocated mandibular condyle fractures in the rabbit

PURPOSE

The purpose of this study was to clarify the influence of patients age and the degree of dislocation on the healing of mandibular condyle fractures.

MATERIAL AND METHODS

Sixty-two Japanese white rabbits (30 adolescent and 30 adult ones) were used. They underwent unilateral condylar neck osteotomy. The proximal fragments were positioned differently. In group I animals, the fragments were reduced into the original position, in group II animals the small fragment was dislocated 55-90 degrees to the ramus. In group III animals the proximal fragment was dislocated 135 degrees to the ramus. Gross and microscopic assessment was performed 4, 6, 8, 12 and 24 weeks postoperatively.

RESULTS

In adolescent animals, complete healing of the fracture was observed, irrespective of the degree of dislocation. In the adult animals, there was complete healing of the fractures in groups I and II. In group III animals, there was a decrease of ramus height accompanied by some fibro-cartilaginous changes.

CONCLUSION

Even in rabbits condylar deformation has been found following heavily dislocated artificial condylar fractures in adult animals. This result will help to decide for or against surgical treatment of condylar fractures in humans.

Cranio-maxillofacial trauma: a 10 year review of 9,543 cases with 21,067 injuries

INTRODUCTION

Cranio-maxillofacial trauma management requires pertinent documentation. Using a large computerized database, injury surveillance and research data describe the whole spectrum of injuries. The goal of this study was to assess the effect of the five main causes of accidents resulting in facial injury on the severity of cranio-maxillofacial trauma.

PATIENTS AND METHODS

During a period of 10 years (1991-2000) 9,543 patients were admitted to the Department of Oral and Maxillofacial Surgery, University Hospital of Innsbruck with cranio-maxillofacial trauma. Data of patients were prospectively recorded including cause of injury, age and gender, type of injury, injury mechanisms, location and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures and concomitant injuries. Statistical analyses performed included descriptive analysis, chi square test, Fisher's exact test, and Mann-Whitney's U test. This was followed by logistic regression analyses for the three injury types to determine the impact of the five main causes on the type of injury at different ages in facial trauma patients.

RESULTS

Five major categories/mechanisms of injury existed: in 3,613 (38%) cases it was activity of daily life, in 2991 (31%) sports, 1170 (12%) violence, in 1,116 (12%) traffic accidents, in 504 (5%) work accidents and in 149 (2%) other causes. A total of 3,578 patients (37.5%) had 7,061 facial bone fractures, 4,763 patients (49.9%) suffered from 6,237 dentoalveolar, and 5,968 patients (62.5%) from 7,769 soft tissue injuries. Gender distribution showed an overall male-to-female ratio of 2.1 to 1 and the mean age was 25.8+/-19.9 years; but both varied greatly depending on the injury mechanism (facial bone fractures: 35.4+/-19.5 years, higher risk for males; soft tissue injuries: 28.7+/-20.5, no gender preference; dentoalveolar trauma: 18+/-15.6, elevated risk for females). For patients sustaining facial trauma, logistic regression analyses revealed increased risks for facial bone fractures (225%), soft tissue lesions (58%) in patients involved in traffic accidents, and dental trauma (49%) during activities of daily life and play accidents. When compared with other causes, the probability of suffering soft tissue injuries and dental trauma, but not facial bone fractures, is higher in sports-related accidents, 12 and 16%, respectively.

CONCLUSION

This study differentiated between injury mechanisms in cranio-maxillofacial trauma. The specially trained surgeons treating cranio-maxillofacial trauma are the primary source of information for the public and legislators on implementing preventive measures for high-risk activities. In facial trauma, older persons are prone to bone fractures (increase of 4.4%/year of age) and soft tissue injuries (increase of 2%/year of age) while younger persons are more susceptible to dentoalveolar trauma (decrease of 4.5%/year of age).

Efeitos da fratura de corpo da mandíbula no crescimento da maxila e da mandíbula: estudo experimental em ratos jovens

Objetivo: Observar os efeitos da fratura experimental de corpo de mandíbula no crescimento da maxila e mandíbula. Métodos: Utilizando ratos com um mês de idade. Estes foram distribuídos em dois grupos: experimental, onde foi efetuada a fratura de corpo de mandíbula à direita, e controle-operado, no qual foi realizado apenas o acesso cirúrgico. Aos três meses de idade foi realizada a eutanásia e após a maceração, a mandíbula foi desarticulada. O crânio foi submetido à incidência radiográfica axial e as hemi-mandibulas à incidência radiográfica lateral. Com base nestas, foram feitas mensurações cefalométricas por meio de um sistema de computador e os valores submetidos a análises estatísticas. Resultados: O comprimento da maxila, bem como a altura e o comprimento da mandíbula apresentaram diferença significante a menor para o lado direito, no grupo experimental. No grupo controle-operado houve diferença significante a menor para o comprimento da porção posterior da maxila e para a altura e comprimento da mandíbula para o lado direito. O grupo experimental quando comparado ao grupo controle-operado mostrou ser significativamente menor em todas as mensurações da maxila e mandíbula para ambos os lados, com exceção do comprimento da mandíbula. Conclusão: A fratura de corpo da mandíbula, bem como a abordagem cirúrgica, tiveram efeitos negativos no crescimento da maxila e da mandíbula.

Rotated subcondylar process fracture in the growing animal: an experimental study in rats

Unilateral, rotated subcondylar fractures were surgically induced in young rats under general anaesthesia. A decrease in body weight was observed in the fractured animals, with recovery at the end of the experimental period. A tendency of deviation of the mandible to the fracture side was noticed on axial radiographs, but without significant difference between experimental and sham-operated animals. Histological data initially demonstrated acute inflammation along the articular capsule and adjacent muscle fibres. Within 2 weeks, exuberant callus formation occurred. Neither devitalized bone ends nor intra-articular granulation tissue were seen. After 1 month, the temporomandibular joint presented characteristics of normality, with the condylar process centralized into the temporal fossa, interposed by the articular disc. These results were preserved after 3 months. We concluded that rotational subcondylar fractures in young rats heal by callus formation, with simultaneous and prompt repositioning of the condyle.

Remodelling following condylar fractures in children

PURPOSE

In this study, 18 children with 21 subcondylar fractures sustained during their growth period (age at trauma from 4-11 years, mean 7.7 years) have been followed-up.

MATERIAL AND METHODS

All patients were treated by custom-made arch bars and intermaxillary fixation for 12-17 days, then kept on a liquid diet for 15 days without fixation. The mean follow-up was 4.7 years. The conservative treatment has been evaluated with clinical, radiographic, and functional parameters.

RESULTS

Remodelling of the condylar head was good in 17, whilst moderate remodelling occurred in the other four condyles. In four patients, a slight deflection (less than 2 mm) to the side of the fracture on wide mouth opening was seen. There was no malocclusion or ankylosis.

CONCLUSION

Conservative treatment of condylar fractures during growth resulted in good function and good remodelling of the condyle. Functional treatment after intermaxillary fixation for 12-17 days proved to be quite acceptable.