Tom D. Daley

Relative incidence of odontogenic tumors and oral and jaw cysts in a Canadian population

The diagnoses of 40,000 consecutively accessioned oral biopsies from the Oral Pathology Diagnostic Service, University of Western Ontario, London, Canada, were reviewed. All odontogenic neoplasm, neoplasm-like lesions (tumors), and true cysts of the oral tissues and jaws were listed. Clinical data were reviewed, and microscopic diagnoses were confirmed for cases in which diagnoses were ambiguous. Records of all cases were examined to identify distant referrals that were not representative of the study population. Of a total of 445 (1.11%) odontogenic tumors, 392 (0.98%) were lesions from patients in the usual local drawing area of the biopsy service; 53 were referred from distant centers. From the local population, odontomas were by far the most common tumor (51.53%) followed by ameloblastomas (13.52%) and peripheral odontogenic fibromas (8.93%). Locally, radicular (periapical) cysts were the most common odontogenic cyst (65.15%) followed by the dentigerous cyst (24.08%) and the odontogenic keratocyst (4.88%). The most common nonodontogenic cyst was the nasopalatine duct cyst that accounted for 73.43% of this subset of cysts. Surprisingly few studies of this type are available, especially for odontogenic tumors. These data are important to assess geographic differences in the incidence of lesions and to allow clinicians to make realistic judgments in counseling patients before biopsy about the probability of diagnosis and risks associated with nonspecific clinical or radiographic lesions.

Clinical and pharmacologic correlations in cyclosporine-induced gingival hyperplasia

Cyclosporine-induced gingival hyperplasia was investigated in a clinical study of 100 patients over a period of 2 1/2 years. Seventy percent of the patients exhibited at least mild gingival hyperplasia. For doses within the therapeutic range, no direct correlation was found between the oral dose or the serum trough concentration of cyclosporine and the severity of gingival hyperplasia. The presence of dental plaque was found to be related to the presence of gingival hyperplasia, but only a weak correlation existed between the abundance of plaque and the severity of gingival hyperplasia. Children and especially adolescents had a greater risk of developing cyclosporine-induced gingival hyperplasia than adults had. In 21 patients followed for 1 to 18 months after cessation of cyclosporine therapy, induced gingival hyperplasia was found to be clinically reversible.

The small dentigerous cyst: A diagnostic dilemma

The dentigerous (follicular) cyst is recognized as one of the most common lesions of the jaws. Clinical, radiographic, histologic, and prognostic characteristics are well established for medium to large pericoronal cysts that are lined by nonkeratinized stratified squamous epithelium. However, it can be difficult, if not impossible, to distinguish between a small dentigerous cyst and a large dental follicle despite the availability of both radiographic and histologic information. Epidemiologic data derived from a comparative study of 1662 dentigerous cysts and 824 dental follicles showed considerable overlap in age distribution and site predilection and were therefore of minimal use in reaching a final diagnosis. At present, it appears that identifying a cystic cavity at the time of surgery may be the only reliable way to arrive at a definitive diagnosis when radiographic and histologic features are insufficient to distinguish between a small dentigerous cyst and a large dental follicle.

TGF-β1 and FAK Regulate Periostin Expression in PDL Fibroblasts

Recently identified as a key component of the murine periodontal ligament (PDL), periostin has been implicated in the regulation of collagen fibrillogenesis and fibroblast differentiation. We investigated whether periostin protein is expressed in the human PDL in situ and the mechanisms regulating periostin expression in PDL fibroblasts in vitro. With immunohistochemistry, periostin protein was identified in the PDL, with expression lower in teeth with reduced occlusal loading. In vitro application of uniaxial cyclic strain to PDL fibroblasts elevated periostin mRNA levels, depending on the age of the patient. Treatment with transforming growth factor-beta1 (TGF-β1) also significantly increased periostin mRNA levels, an effect attenuated by focal adhesion kinase (FAK) inhibition. FAK-null fibroblasts contained no detectable periostin mRNA, even after stimulation with cyclic strain. In conclusion, periostin protein is strongly expressed in the human PDL. In vitro, periostin mRNA levels are modulated by cyclic strain as well as TGF-β1 via FAK-dependent pathways.

Peripheral odontogenic fibroma

The peripheral odontogenic fibroma is characterized by a fibrous or fibromyxomatous proliferation that contains varying amounts of odontogenic or presumed odontogenic epithelium. It has been considered a rare gingival neoplasm that, because of a lack of follow-up information in most reported cases, has had an unknown biologic behavior. Clinical data from this study indicate that the lesion is more common than previously reported and that it has a significant recurrence rate. Light and electron microscopic data reveal a relatively broad spectrum of epithelial and mesenchymal components, including a rare granular cell type. Because the presence of both epithelial and mesenchymal elements are required for its diagnosis, the lesion is logically classified as a mixed epithelial/mesenchymal odontogenic tumor, rather than a purely mesenchymal tumor.

Canalicular adenoma: Not a basal cell adenoma

The evidence that canalicular adenomas and basal cell adenomas are separate entities is presented in this article. The clinical features were studied in a series of 13 previously unreported salivary gland tumors (5 canalicular adenomas and 8 basal cell adenomas) and 99 examples derived from the literature (68 canalicular adenomas and 31 basal cell adenomas). Representative tumors from the new cases and from 66 referred cases were studied by histologic, histochemical, and electron microscopic techniques. The two tumors differ significantly with respect to the age range of affected patients, site of predilection, and morphologic and histochemical features.

The use of the termsmonomorphic adenoma, basal cell adenoma, andcanalicular adenoma as applied to salivary gland tumors

There is considerable confusion in the literature concerning the terms monomorphic adenoma, basal cell adenoma, and canalicular adenoma. This article traces the history of these terms as applied to the pathology of salivary gland tumors and attempts to clarify their usage. It is recommended (1) that monomorphic adenoma be used, as it was originally intended, as a nosologic grouping for all benign epithelial salivary gland tumors that are not pleomorphic adenomas, (2) that basal cell adenoma be used to identify a specific entity that is one component of the monomorphic adenoma group and exhibits a number of histologic subtypes, and (3) that canalicular adenoma be used to describe another entity, distinct from basal cell adenomas but also belonging to the monomorphic adenoma group.

Oral manifestations of gastrointestinal diseases.

The present paper offers a detailed review of the oral manifestations of various gastrointestinal diseases or conditions, with suggestions on how they may be relevant to the practice of gastroenterology. The review includes Crohns disease, ulcerative colitis, Gardner syndrome, Peutz-Jeghers syndrome, malabsorption conditions related to hematopoesis, gastrointestinal malignancy metastatic to the jaws, jaundice and gastric reflux diseases.

Epithelial-myoepithelial carcinoma of salivary glands

Four cases of epithelial-myoepithelial carcinoma of salivary gland origin are presented and discussed. The mean age of these four patients was 68 years, with an age range of 51 to 78 years. Three of the patients were women, and one was a man. This article emphasizes the light microscopic, histochemical, and ultrastructural features of the neoplasm. Electron microscopic examination of glutaraldehyde-fixed fresh tissue and previously formalin-fixed tissue reveals that the characteristic clear cytoplasm of abluminal cells is caused, in part, by glycogen storage granules and the paucity of organelles but largely by an artifact of fixation.

Metallothionein in human gingival amalgam tattoos

Amalgam tattoos occur when small particles of dental amalgam, composed largely of silver (Ag) and mercury (Hg), are inadvertently implanted into oral soft tissues during dental procedures. Metallothioneins (MTs) are ubiquitous, low molecular weight, cysteine-rich, metal-binding proteins that are inducible by many agents including metals and may be involved in the detoxification of toxic metals such as Hg. In this study, the correlation between MT expression and amalgam tattoos in human gingiva was investigated using energy-dispersive X-ray microanalysis (EDX) and immunohistochemical techniques. Light microscopically, amalgam tattoos presented as either fine granular particles or larger discrete opaque globular particles in connective tissues. EDX revealed the smaller particles to be silver sulphide (Ag(2)S), while the larger particles exhibited a shell of Ag(2)S that contained irregularly distributed masses of Ag and Hg. Particles of tin (Sn) were also found. No MT staining was observed in collagen, fibroblasts or blood vessels in areas exhibiting abundant amounts of embedded fine granular Ag(2)S particles. Blood vessels exhibiting relatively few amalgam particles stained positively for MT. Cells with the morphological features of histiocytes located directly adjacent to larger pieces of amalgam showed intense MT staining. These results indicate that amalgam tattoos contain no Hg or free Ag except in large globular pieces of amalgam, which still contain Hg and which induce MT expression in adjacent histiocytes. This suggests that Hg leaching from impacted dental amalgam particles induces MT, while residual Ag(2)S and Sn particles do not. MT may therefore act to reduce Hg exposure in patients with amalgam tattoos.