The type, origin and function of the odontogenic cells of continuously growing guinea-pig molars.

Little is known about which cell types act as the origin of odontogenic stem cells and how these stem cells differentiate to become functional. In the present study 3-day-old guinea-pigs were injected with tritiated thymidine, killed at intervals and their molars studied. The odontogenic cells were found to originate from the stem cells which by autoradiography were shown to be slow cycling and lightly labelled. As they differentiated they became heavily labelled and were designated transit 'dividing cells'. With further differentiation the cells were unlabelled and were designated 'simple transit cells'. It was concluded from the present study that outer enamel epithelium functioned as the source of all odontogenic epithelium; that primitive mesenchyme around the cervical loop functioned as the source of all odontogenic mesenchyme and that all of the transit cells which differentiated to become functional migrated coronally.

A histological investigation of isografts of mature mouse molars to an intrabony and an extrabony site.

An experimental model designed for the investigation of tooth transplantation immunobiology is presented together with the results of a long-term histological study of mature mouse tooth isografts transplanted to an intrabony site (tibial shaft medulla) and to an extrabony site (renal subcapsular site). Mature mouse mandibular third molars were isografted to the tibial shaft medulla and renal subcapsular kidney site in inbred C57BL/6 strain mice and observed histologically over a 6-month period. Isografts at both sites were observed to undergo initial pulpal degeneration with subsequent progressive regeneration as determined by post-transplantation dentine formation. Tibial shaft isografts were surrounded by bone and underwent progressive reabsorption beginning at the coronal dentine, exposed by occlusal wear prior to transplantation, while grafts to the subcapsular kidney site did not become surrounded by bone nor exhibit coronal resorption. Varying degrees of external root resorption and ankylosis of teeth transplanted to the intrabony site were observed, and signs of periodontal ligament reorganization were not seen in isografts at either site.

Serum antibody response to mature tooth allografts in mice.

Mature mouse molar teeth were transplanted to the tibial shaft medulla across an H-2 plus multiple non-H-2 histocompatibility barrier. Over the 35-day experimental period, low levels of complement-fixing antibody were detected in the serum of recipients. Antibody was distributed over two peak periods, 6 to 11 days and 21 to 27 days after transplantation, with IgM apparently preceding IgG production.

A histological investigation of allografts of mature mouse molars to an intrabony and an extrabony site.

Fully developed mandibular third molar teeth, allografted across an H-2 plus multiple non-H-2 barrier to the tibial shaft medulla and renal subcapsular site in mice, were examined histologically over a 12-month period after transplantation. Cellular degeneration within the pulp chamber occurred in the immediate post-transplantation period and was followed by pulp chamber repopulation by a vascular fibrous connective tissue during the first 14 days after transplantation. Progressive regeneration of the grafts occurred and was characterized by irregular tubular dentine formation followed by more organized tubular dentine deposition on the pulp chamber walls. Allografts at both sites eventually underwent rejection, and it was apparent that grafts at the subcapsular kidney site were rejected in a shorter time (35 to 56 days) than those at the tibial shaft site (56 to 70 days). When mature teeth were allografted to the tibial shaft medulla across multiple minor (non-H-2) barriers alone, similar changes were observed with grafts undergoing rejection 56 to 70 days after transplantation. External root resorption and ankylosis were not prominent features and periodontal ligament reorganization was not observed in any of the grafts.

Xenografts of recombined bovine odontogenic tissues and cultured cells to hypothymic mice.

It was demonstrated in this study that recombined tissues of bovine dental papilla and reduced enamel epithelium, when transplanted to the subcapsular kidney site of hypothymic mice, elaborated tissues resembling osteodentin and dentin matrices with which latter tissues were closely associated cells resembling odontoblasts. In xenografts of cultured cell populations of these tissues, osteodentin-like matrices occurred in the absence of dentin-like matrices.

Transplantation of bovine odontogenic tissues and dissociated odontogenic cells to hypothymic mice.

It was demonstrated in this study that bovine odontogenic tissues and the dissociated cell preparations of such tissues, when transplated to the subcapsular kidney site of hypothymic mice, retained their phenotypic expression and continued function to produce their recognisable products, dentine and enamel matrices. It was also shown that in the grafts of dissociated odontogenic tissues, cell sorting occurred so that histotypical tissues were formed and that their function produced readily recognisable dentine and enamel matrices. Attention has been drawn to the usefulness of this model for studying a variety of events that occur during odontogenesis.

The management of dural tear resulting from mid-facial fracture.

This study examines the relative risks and benefits of conservative and surgical management of dural tear secondary to middle third facial fracture and ascertains the type of skull and facial injury most often associated with the development of posttraumatic meningitis. Two projects were undertaken. First, the histories of 247 cases of major middle third facial fracture were reviewed with a recent follow-up of those patients who also sustained a dural tear. Second, 280 cases of bacterial meningitis were reviewed and particular attention was given to cases of posttraumatic meningitis. Of the 247 cases of middle third facial fractures studied, 43% (107/247) had evidence of a dural tear; of this group, 76 patients were managed conservatively and 31 patients were managed surgically. In the former group, there were three instances of recurrent cerebrospinal fluid rhinorrhea (CFR). In the surgically managed group, 77% (24/31) sustained surgical complications including two cases of posttraumatic meningitis and 21 cases of neurological deficit. Of the 280 cases of bacterial meningitis, 48 patients had sustained dural tear following trauma. The prognosis for posttraumatic meningitis is considerably better than for other forms of meningitis. The preceding trauma involved the vault of the skull in 90% (43/48) of cases, and discrete middle third facial fracture in one case (2.1%). Posttraumatic meningitis followed a previous operative repair in 15% (7/48) of the patients. The results of this study indicate that dural tear subsequent to middle third facial fractures is a different proposition than dural tear subsequent to direct skull trauma.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermal growth factor and proliferation of odontogenic cells in culture.

The proliferation of bovine odontogenic epithelial (OE) and mesenchymal (OM) cells cultured in the presence of varying concentrations of epidermal growth factor (EGF) was examined. After a delay of two to three d, EGF-supplemented cultures contained significantly more cells than did controls. This effect was dose-dependent, was maximal at 10-9 g EGF/ml for OE and 10-8 g EGF/ml for OM, and was dependent on the presence of serum in the culture medium. The results suggest the possibility that EGF may play a role in the control of odontogenic cell proliferation in vivo.

Ultrastructural changes to the palatal mucosa of rats following the application of 4-nitroquinoline-1-oxide (4NQO) and vitamin C.

Oral mucosal neoplastic disease in rodents has been induced by various chemical carcinogens, including water soluble 4-nitroquinoline-1-oxide (4NQO). It has been suggested that vitamin C can inhibit, delay or prevent the development of neoplasms, as well as enhance the induction of neoplasia. In this investigation, 4NQO was used to produce a high yield of carcinomas of the palatal mucosa of rats in a relatively short period of time and topical vitamin C was applied to delay the neoplastic transformation. The temporal aspects of the ultrastructural changes occurring in 4NQO-induced oral palatal mucosa treated with both 4NQO and vitamin C have been described and discussed.

A histological investigations of isografts of immature mouse molars to an intrabony and extrabony site.

Partially-developed teeth with remnants of their periodontal ligaments isografted to the tibial shaft medulla and renal subcapsular site were capable of progressive regeneration characterized by renewed tubular dentine formation. Bone formation occurred in relation to grafts at the renal site as well as the tibial shaft; evidence of periodontal fibre reorganization was observed in grafts at both sites. Despite post-transplantation dentine and cementum formation, continued development of roots of normal morphology did not occur, perhaps due to disappearance of epithelial root sheath.

Temporomandibular disorders: a critical review of the nature of pain and its assessment.

Temporomandibular disorders is a common form of chronic pain affecting the head, face, and jaw. The distinguishing symptoms of this disorder include pain and impairment of the masticatory function, and frequent display of symptoms, ranging from aches in the head, neck, ears, and eyes, to atypical toothaches, throat symptoms, and occlusal changes. It is recognized that pain is a complex, multifactorial experience including not only sensory dimensions, but also affective and cognitive factors. Recent recommendations regard temporomandibular disorders as a dual-axis disorder with physical and psychologic dimensions, but little research has incorporated measures of multidimensional pain characteristics in the assessment of temporomandibular disorders. This article is a review of the literature on the psychophysiologic factors contributing to temporomandibular disorders and its limitations. Recommendations for future research are also given.

Temporomandibular disorders. Part I: A comparison of symptom profiles in Australian and Finnish patients.

Variability in the assessment methods of patients seeking treatment for musculoskeletal disorders of the masticatory system confounds comparative assessment of different studies. In this study, presenting symptom profiles were assessed in 40 Australian and 42 Finnish patients with temporomandibular disorders. The symptom parameters of these patients were compared with those of 40 Australians reporting acute dental pain and were assessed with reference to response to conservative management. A self-administered anamnestic questionnaire was used in a standard, systematic, and comparative way to assess demographic data, general health status, and symptom parameters according to type, frequency, severity, duration, location, impact on the patients' lives, urgency for need of treatment, and possible initiating factors. It was found that the two nationalities studied had similar presentations of cardinal symptom profiles. Statistically significant differences in major presenting symptoms were found between patients with temporomandibular disorders and those with acute dental pain, but not between patients who responded rapidly as opposed to slowly to conservative therapy. It was concluded that the presenting symptom profiles were similar for the two nationalities and were not related to treatment outcome.

Temporomandibular disorders: Part II. A comparison of psychologic profiles in Australian and Finnish patients.

Recent recommendations regard musculoskeletal disorders of the masticatory system as dual-axis disorders, but little comparative data of psychologic factors across different pain populations are available. In this study, presenting psychologic profiles were assessed in 40 Australian and 42 Finnish patients diagnosed with temporomandibular disorders. Findings were compared with those of a group of Australian patients reporting acute dental pain and with reference to response to conservative management. The psychologic testing instrument incorporated cognitive, motivational/affective, and illness behavior variables, and it was based on validated general pain questionnaires (Coping Strategies Questionnaire and Illness Behavior Questionnaire). This instrument was found internally reliable in the majority of its subscales in the group studies and provided comparable data to other pain populations. Significant differences in the presenting psychologic profiles were found according to nationality, type of pain suffered, and treatment outcome. Affective disturbance, hypochondriasis, lack of cognitive control, and feeling ill with symptoms were identified in discriminant function analysis as potential predictors of treatment outcome, and they correctly classified 79% of the Australian and 87% of the Finnish patients with temporomandibular disorders. It was concluded that psychologic profiles differed in the two nationalities and were related to treatment outcome. The concept of multiaxial assessment was supported.

Psychophysical subtypes of temporomandibular disorders.

This study presents an approach to the classification of temporomandibular disorders (TMD) based on acknowledgement of the interaction of physical, psychologic, and social factors using a multidimensional instrument that has been previously validated. The psychometric properties of this instrument were reevaluated in 140 women with TMD. Multidimensional clustering identified three subgroups of patients with TMD, including a highly distressed, psychosocially maladaptive group; a moderately distressed, behaviorally functional group; and a predominantly physical disorder group with an unremarkable psychosocial profile. These groups were termed maladaptive, adaptive, and uncomplicated, respectively, according to the constellation of predominant symptoms and psychosocial profiles of each cluster. The groups showed no consistent differences in pain frequency, use of medication, or duration of pain. This finding supports earlier work that suggested the prominence of three subtypes of this disorder according to both physical illness and psychosocial illness impact parameters.

An intraoral splint for the prevention of microstomia from facial burns.

Microstomia may be a disfiguring complication of severe burn injuries of the soft tissues of the face. The constriction of the perioral myocutaneous tissues following such trauma poses several problems and usually necessitates major plastic and reconstructive intervention. A novel technique is described which limited the anticipated constriction of perioral tissues in a 21-year-old female who suffered full skin thickness burns to 65 per cent of her body, including her face, following a self-induced petrol burn.

Tobacco smoking habits and attitudes of Australians with oral mucous membrane keratoses.

The purpose of this study was to ascertain whether or not a relationship existed between the presence of oral mucous membrane keratoses and tobacco smoking habits. Two groups of tobacco smokers, one group exhibiting oral mucous membrane keratoses, and the other no such changes, were chosen for their similar smoking habits. Detailed tobacco smoking histories of each group were ascertained. Similar results for both groups, in terms of the number of years of smoking, quantity of tobacco consumed dialy, type of tobacco smoked and the method of inhalation and exhalation were found. Eighty per cent of patients wanted to stop smoking with the fear of cancer being the major reason in the subjects with oral keratoses and the continued cost of smoking the major reason in the control subjects. In the affected patients the prevalence of white patches was not related to the quantity of tobacco consumed but rather to the number of years the subject had smoked.

A dental survey of Tibetan children in Dharamsala.

Since their exodus in 1959 about 100,000 Tibetans have settled in disparate communities in northern India and Nepal. This study describes the dental health of 243 Tibetan children in Dharamsala, in the State of Himachal Pradesh, India. Only 20% of 6-yr-olds were caries-free in the primary dentition while 96.9, 53.3, and 22.4% of 6, 12, and 15-yr-olds were caries-free in the permanent dentition respectively. The DMFT of 12-yr-old children was 1.1, while 15-yr-old children had a DMFT of 3.1. While plaque and calculus were present in many sextants, there was little intense gingivitis and signs of advanced periodontal diseases were rarely present. Almost no dental care had been received. Appropriate dental health promotion activities are discussed.

Exfoliative cheilitis--a factitious disorder?

Exfoliative cheilitis is an uncommon lip lesion usually of great concern to the patient and quite refractory to treatment. The available literature was surveyed, and 3 cases have been described to illustrate various aspects of the condition. The difficulty of treating such lesions has been discussed, and a proposition put forward that the lesions are of a factitious nature.

Erythema multiforme and Mycoplasma pneumoniae infection. Report and discussion of a case presenting with stomatitis.

A case report is presented in which a respiratory tract infection with M. pneumoniae appears to have provoked a generalised mucocutaneous disease, described as Stevens Johnson syndrome. The patient possessed complement-fixing antibodies to M. pneumoniae to a titre of 1/2048 compared with the general population titre of 1/32. The oral mucosal lesions are described in particular and a likely pathogenesis of erythema multiforme is discussed.

Hemifacial atrophy and temporomandibular joint pain-dysfunction syndrome.

A case is described of a patient with progressive HA who presented because of left TMJ pain, jaw locking and ipsilateral masticatory muscle spasm. Several reports exist in the literature of masticatory muscle spasm associated with HA. A diagnosis of TMJPDS was made and an occlusal splint was provided which produced resolution of the TMJ pain and jaw locking and significantly reduced the masticatory muscle spasms.