Search

While there is considerable evidence that skin carcinogenesis proceeds as a step-wise series of changes, little evidence is available to indicate that a similar mechanism applies to oral mucosal carcinogenesis. In the current study, a mouse model of mucosal carcinogeniesis was used to examine the effects of repeated applications of phorbol ester phorbol-12,13dedecanoate (PDD) following various periods of treatment with the carcinogen 4-nitroquinoline-1-oxide (4NQO). All animals were histologically examined at 50 weeks. oral epithelial dysplasia was seen in animals treated with 4NQO for as little as 2 weeks, and oral squamous cell carcinomas developed in all animals treated with 4NQO for 16 weeds. In those mice treated with PDD as well, carcinomas developed in mice receiving as little as 2 weeks treatment with 4NQO, and 100% of mice treated with 4NQO for 12 weeks, followed by PDD treatment, developed carcinomas. The results indicate that irreversible changes in the oral mucosa of mice occur relatively early during treatment with 4NQO, and the development of carcinomas can be enhanced with subsequent PDD treatment, giving an indication of staged carcinogenesis in this model system. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Since their exodus in 1959 about 100000 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. [ABSTRACT FROM AUTHOR]

Squamous cell carcinomas of the tongue can be produced reliably in rats by repeated application of the carcinogen 4-nitroquinoline-1-oxide. The histopathological changes in the lingual epithelium during carcinogenesis were progressive, passing through mild to moderate to severe epithelial atypia before the development of squamous cell carcinoma. Initiation, with its putative irreversible cellular changes, occurred within 4 weeks.

Routine histological and indirect immunofluorescence techniques were used to examine the histological details of changes in the distribution of epidermal growth factor (EGF) in the submandibular salivary glands of mice during secretion. Comparisons were made bewteen glands of normal mice and those of mice given one of a number of secretagogues at various times prior to sampling. Normal submandibular salivary glands in male mice had an extensive system of convoluted granular tubules (CGT), the cells of which contained EGF. When adrenaline of alpha-phenylephrine was administered, the CGT cells degranulated, and there was a concomitant loss of intracellular EGF-positive immunofluorescence. The excretory ducts were engorged with immunofluorescent material, indicating secretion of EGF into saliva, while the ductal cells themselves remained EGF-negative. The degranulation response could be blocked by phentolamine, but not by propranolol, and no changes in EGF distribution followed the administration of pilocarpine. It was concluded that EGF is secreted, at least partly into the saliva, following an alpha-adrenergic response, and that this occurs with degranulation of the cells of the CGT.

A single dose of 800 rad x-irradiation was shown to cause degranulation of the cells of the convoluted granular tubules of adult male Swiss white mice. By direct immunofluorescence, the degranulation was found to be associated with loss of immunoreactive epidermal growth factor (EGF) from the convoluted granular tubules. Immunoreactive EGF was found in some cells of tubules that were severely degranulated, and this was interpreted to be related to the greater sensitivity of the immunofluorescence method. The degranulation progressed from 2 h post-irradiation to be complete by 2 days, from which time a slow return to normal granular appearance and EGF-positive immunofluorescence occurred by 76 days. It was found that the degranulation process could be inhibited by the alpha-adrenergic blocking drug phentolamine (1 mg/ml in drinking water) suggesting that the effect of the x-irradiation was at least partly mediated by way of an alpha-adrenergic mechanism. It was speculated that this mechanism could have derived from an effect of the x-irradiation on neural elements, or by way of increased circulating catecholamines caused by the stress of the x-irradiation, in addition to direct effects of irradiation on the cells of the convoluted granular tubules.

The oral mucosa of mice is resistant to the action of a variety of carcinogens. In this study, the water-soluble carcinogen 4-nitroquinoline-1-oxide (4NQO) was applied repeatedly to the palates of male CBA mice for 2, 4, 6, 8, 12, or 16 weeks, and the animals were observed for the remainder of the 50-week experimental period. Oral epithelial atypia and squamous cell carcinoma were observed with increasing prevalence as the period of carcinogen exposure was increased. Carcinomas developed by 50 weeks in all animals that received 4NQO for 16 weeks.

Seven cases of dentinal dysplasia Type I and a case of dentinal dysplasia Type II have been presented, and the literature concerning these rare disorders has been reviewed. Attention has been drawn to the important clinical and histological features of these dental abnormalities.

Whilst the content of epidermal growth factor in the submandibular salivary glands has been considered to be controlled primarily by the hormonal secretions of the testes, our previous studies indicated that the adrenal glands also affect the cellular content of epidermal growth factor in these glands. In the present study, the influence of the thyroid gland was investigated. One hundred and ten males Swiss White mice were subjected to orchidectomy and/or bilateral adrenalectomy, or thyroidectomy, and their submandibular salivary glands examined at 90 days of age. Some of these received specific hormone replacement prior to examination of the glands. The presence of epidermal growth factor was detected by indirect immunofluorescence, and adjacent sections of tissue were stained with alcian blue and acid fuchsin to demonstrate the convoluted granular tubules, which are the site of storage of the factor in the glands. In the glands of normal males, these tubules were prominent and showed strong factor-positive immunofluorescence. Administration of thyroxine reversed orchidectomy-induced atrophy of the tubules, and restored factor content, but did not restore normal tubular morphology or factor content in orchidectomised-adrenalectomised animals. In these latter animals, combined administration of thyroxine and cortisone resulted in a return to normal structure and growth factor content in the cells of the convoluted granular tubules. The glands from thyroidectomised males had atrophied tubules, which did not contain demonstrable epidermal growth factor. These effects were reversed by the administration of thyroxine, testosterone, thyroxine and testosterone, or thyroxine and cortisone. The results show that the content of epidermal growth factor-positive cells in the convoluted granular tubules of the submandibular salivary glands of male mice is under the control of the thyroid as well as the testes and adrenal glands.

Residual complications associated with middle third facial fractures have been poorly documented in the literature. In the present study, 240 patients with fractures of the middle third of the facial skeleton, who were treated at the Royal Melbourne Hospital, Victoria, between 1969 and 1976, were reviewed to determine the residual complications of these fractures. Cranial complications were relatively uncommon, and 60 % of cases of cerebrospinal fluid rhinorrhoea ceased within 3 days of fracture reduction and fixation. Persistent infraorbital sensory defects occurred in 22 % of patients with Le Fort II or Le Fort III fractures. Orbital complications included diplopia, which remained in 8 % of cases, and was often corrected by secondary surgery. Residual complications involving the nose or maxillary sinus were uncommon (less than 5 %). Occlusal disharmony was present as a residual problem in 19.6 % of cases, although this could be managed by simple means in 89 % of these cases so that primary surgery and simple secondary dental procedures a satisfactory result in 98 % of all patients. The low incidence of dental complications is most likely a result of the rigid fixation employed in the fracture management, allowing accurate control of the bone fragments.

The clinical sign of a 'halo-like' white border to an ulcer of the oral mucosa is discussed and the pertinent histopathology described. The term 'peripheral keratosis' has been applied to this appearance which can be useful in the initial clinical assessment of an oral mucosal ulcer.

In a retrospective study of 240 patients with major fractures of the middle third of the facial skeleton, the incidence, anatomical patterns, and management of these fractures have been reviewed, and an assessment made of the concomitant injuries to other organs. Most of the fractures occurred in the 20-29-year age group (39%), and over 83% of the patients in this study were males. The most common cause of injury was road accidents (80.8% of all cases), and automobile occupants represented most of this group. The Le Fort II fracture was the most commonly sustained, and there were several variations from the classical fracture patterns recorded, combinations of fractures at different levels being frequent. Ninety percent of patients had another concomitant injury, indicating the need for multi-disciplinary care of this type of patient. The most common treatment method involved the use of craniomaxillary and intermaxillary fixation, which was usually maintained for 22-28 days.

Coronoidotomies were performed in laboratory rats in order to describe the histological features of the healing process. In all longer-term specimens, the coronoid process reattached to the mandibular ramus by means of intracartilagenous bone formation within 4-6 weeks of surgery. This finding may give some indication of events occurring in humans following coronoidotomy.

A case of aneurysmal bone cyst of the mandible in a 21-year-old female has been presented, and the pertinent literature reviewed. Conservative surgery in the treatment of this type of jaw lesion is recommended.