J.F. Lownie

Maxillofacial injuries in a group of South Africans under 18 years of age

OBJECTIVE To find out the incidence of maxillofacial injuries in South African children aged 18 years or less. DESIGN Retrospective study of casenotes. SETTING Six teaching hospitals affiliated to the University of Witwatersrand, Johannesburg, serving a population of about 5 million people. SUBJECTS All 326 children treated for facial injuries in the maxillofacial and oral departments of the six hospitals between 1 January 1989 and 30 June 1992. MAIN OUTCOME MEASURES Classification of the types of injury, associated injuries, cause of the injury, and methods of diagnosis. RESULTS Of the total of 4192 patients of all ages treated for facial injuries, 326 (8%) were within the age range of the study. The female:male ratio was 1:2.3. Most of the injuries (227, 70%) occurred in the 13-18 age group, and assaults, fights and gunshot wounds accounted for 155 injuries (48%). Of the 326 children, 173 (53%) had single injuries and 153 (47%) had multiple injuries. Mandibular fractures were the most common (64%) followed by maxillomandibular fractures (25%). Violence was the most common cause of injury, as in the USA and Zimbabwe, but unlike the rest of the world in which it is motor vehicle accidents. Soft tissue injuries were the most common associated injuries, and conventional plain radiography was the usual investigation. CONCLUSION The incidence of 8% compares favourably with those in other countries, but far too many injuries are the result of violence.

Chronic osteomyelitis of the jaws

The incidence of osteomyelitis has been greatly reduced since the advent of antibiotics. In many 3rd World countries, however, numerous cases of severe advanced osteomyelitis still present annually. A case of subacute osteomyelitis is reported and the pathology and clinical features of chronic osteomyelitis are reviewed.

Ameloblastic sarcoma of the mandible

Malignant ameloblastic odontogenic tumors have traditionally been classified as either ameloblastic fibrosarcomas, dentinosarcomas or odontosarcomas. This separation is based on the presence of either dentine or dentine and enamel in some lesions. To date, 28 cases of ameloblastic fibrosarcoma, one case of ameloblastic dentinosarcoma, and seven cases of ameloblastic odontosarcoma have been reported in the literature. An additional case of ameloblastic dentinosarcoma is reported in this paper together with a critical review of the clinicopathologic features of previously reported cases of malignant ameloblastic neoplasms. The presence of dental matrix material is not specific and is found in a wide variety of odontogenic tumors in variable amounts. This study supports the concept that the presence of dental matrix material does not alter the basic biologic characteristics of these neoplasms. Accordingly, to simplify a confusing nomenclature, we suggest that malignant tumors of this type be referred to collectively as ameloblastic sarcomas.

Biocompatibility testing of a silicone maxillofacial prosthetic elastomer: soft tissue study in primates.

Little information exists on the biocompatibility of maxillofacial prosthetic materials. Cosmesil material is a purpose-designed facial prosthetic elastomer that has an established clinical profile in humans but results of biocompatibility testing have not been published. Cosmesil, acrylic resin (positive control), black surgical gutta-percha (negative control), and Silastic 382 material (Dow Corning, Midland, Mich.) (reference control) were processed as custom-designed implants. The implants were inserted into five chacma baboons for a 12-week period in intraosseous, subperiosteal, submucosal, and intramuscular sites. The histologic assessment was based on a modified form of the FDI-ISO Technical Report 7405 for subcutaneous implants. An evaluation was made of capsule formation and inflammatory response. The statistical analysis involved a three-way ANOVA and a Tukey-Kramer Student range test. The critical level of statistical significance chosen was p less than 0.05. The study found that gutta-percha provoked a statistically significantly thicker capsule and a severe inflammatory response. Acrylic resin, Cosmesil material, and Silastic 382 material produced capsule formations and an inflammatory response that did not differ significantly. Cosmesil material is not manufactured as an implant material, but from the present findings it is considered acceptably biocompatible for its intended use where there may be contact with internal tissue spaces that are contiguous to external surfaces.

Autotransplantation of maxillary canine teeth. A follow-up of 35 cases up to 4 years.

Abstract 35 cases of autotransplantation of nonendodontically treated maxillary canines were followed for up to 4 years and were assessed according to loss of the transplanted tooth, onset of sensibility, mobility, intact lamina dura and presence of tooth resorption. The results of this study compare favourably with other studies and favour the hypothesis that little is to be gained by not endodontically treating autotransplanted teeth immdiately after splint removal. It is also suggested that immobilization by means of a rigid splint, removing the tooth from occlusal forces, may account for the relatively low incidence of resorption in this series.

Long-term histologic changes in the dental pulp after posterior segmental osteotomies.

OBJECTIVE The purpose of this study was to examine pulp tissue for 18 months after segmental osteotomy in nonhuman primates. STUDY DESIGN In this long-term experimental study, subapical, posterior, maxillary, and mandibular osteotomies were done in 26 baboons (Papio ursinus). Baboons were killed humanely immediately after operation and at 3, 6, 12, and 18 months, when tissues were perfusion-fixed. Longitudinal step-serial sections of dental pulps were examined. RESULTS There was a loss of the odontoblast layer as early as 3 months after surgery. Inflammatory cell infiltrate was most marked in the early postoperative stages, and the formation of osteodentin and secondary dentin was evident after 6 months. Foci of necrosis were present in the 3-month and 6-month groups but were replaced by pulp fibrosis in the 12-month and 18-month groups. All these changes were more frequent in experimental than control teeth. CONCLUSIONS The histologic changes seen should not affect the prognosis of teeth in subapical osteotomy segments if clinicians are careful not to damage root apices and do regular, careful, clinical, and radiographic follow-up examinations. Because many pulps healed spontaneously in the study teeth, endodontic treatment should be delayed until it is clearly needed.

Vascularity of the dental pulp after segmental osteotomy in the chacma baboon (Papio ursinus)

OBJECTIVE To assess the vascularity of the dental pulp after segmental operations with and without interpositional autogenous bone grafting. DESIGN Experimental study. SETTING University Department, South Africa. ANIMALS 26 chacma baboons. INTERVENTIONS Maxillary and mandibular posterior segmental osteotomies were perfused with barium sulphate 3, 6, 12 and 18 months postoperatively. The animals were killed at 3, 6, 12 and 18 months after surgery and perfused with barium sulphate. Barium-filled vessels were counted in histological sections from 189 control and experimental teeth. MAIN OUTCOME MEASURE Number of blood vessels. RESULTS Blood vessel counts in mandibular teeth in osteotomy segments ranged from 0 to 1.15 compared with 2.27 to 4.58 in control teeth, while in maxillary teeth counts ranged from 0.54 to 2.22 for experimental teeth and 3.3 to 4.65 for controls. For both jaws, the numbers of vessels in experimental teeth gradually increased between 3 and 18 months but remained less than those in control teeth. Numbers of blood vessels were similar in graft and no-graft groups but both were less than half the counts in control teeth. CONCLUSION Blood flow is present in the teeth at all times after posterior segmental osteotomy but there is a risk of ischaemia.

Avascular necrosis of the mandibular ramus in the baboon (Papio ursinus) following orthognathic surgery

The maintenance of an adequate blood supply to the mandible following orthognathic surgery is of extreme importance if satisfactory healing is to be achieved. With this object in mind, this study was undertaken to assess the effects of disrupting the blood supply of the baboon mandible by means of L- and C-osteotomies. Ten adolescent baboons of the species Papio ursinus were used as the experimental animals for the study. On five of them a modified vertical subsigmoid osteotomy (L-osteotomy) and on five a C-osteotomy of the mandibular ramus were performed. In each experimental animal the osteotomy was undertaken on one side of the mandible only, the other side serving as a control. After a postoperative period of 14 days the animals were killed, the entire mandible removed, and the tissues prepared for examination with the light microscope. Histometric analysis revealed a significant degree of avascular necrosis in certain areas of the proximal or condylar fragments and to a lesser extent in the distal fragment. Avascular necrosis was also seen on the control side. It was also revealed that the periosteum and attached muscles of mastication play a role in the blood supply of the mandible and that the additional attachment of the temporalis muscle to the proximal fragment is of no advantage in enhancing the vascularity of that fragment.

Effect of a topical drug combination on the early healing of extraction sockets in the vervet monkey

An animal trial was undertaken in 9 vervet monkeys to test the effect of a medicament combination on extraction socket healing. All 4 third molar teeth were extracted and 2 of the sockets in each animal were packed with Gelfoam sponge impregnated with a medicament containing a local anaesthetic, antiseptic, 2 potent antifibrinolytic agents and metronidazole. The remaining 2 sockets acted as controls: one of the sockets was packed with Gelfoam sponge alone and the other allowed to heal spontaneously with no implant. The healing of these sockets was evaluated histometrically in 4-, 6- and 8-day specimens, and from the results it was concluded that sockets containing the medicament compound showed enhanced early socket healing.

A comparison of two methods of inferior alveolar nerve block

The Gow Gates method and a conventional inferior alveolar nerve block method were compared in 100 patients undergoing bilateral extractions of the lower molar or premolar teeth. The Gow Gates technique was significantly less effective than the conventional technique.