Vaporization of melanin in oral tissues and skin with a carbon dioxide laser: a canine study.

PURPOSE: This study tested the efficacy of carbon dioxide (CO2) laser vaporization in ablating gingival, oral mucosal, and cutaneous melanin in dogs. MATERIALS AND METHODS: Three mongrel dogs with pigmentation of the oral mucosa, gingivae, and skin were used. Biopsy specimens from the melanin sites were obtained from all 3 dogs before laser application. Removal of the melanin sites was performed by using a 3 W continuous-wave CO2 laser. Biopsies of the treated areas were performed 1, 2, 4, and 6 weeks after laser treatment in all 3 dogs and also, at 11 weeks in 1 dog. The histologic sections were stained with hematoxylin and eosin and Masson-Fontana dye. A computerized morphometric program calculated the average percentage of the melanin layer in the Masson-Fontana-stained sections. RESULTS: Clinical and histologic examination showed the CO2 laser to be effective in eliminating the pigmented areas in all tissues treated. No recurrence of melanin was detected in either the oral mucosa or gingiva at any of the follow-up times. In the skin, however, a small amount of melanin repigmentation was noticeable. CONCLUSIONS: CO2 laser surgery proved an effective tool for obliterating superficial melanin discoloration. To prevent recurrence of the pigmentation, the area must be cleared completely of melanin, directing the laser beam carefully along the visible margins of the area.

Tumors and tumor-like lesions of the oral cavity and related structures in Israeli children.

The present study comprises a total of 966 biopsies of the oral cavity and related structures obtained from children aged < or =15 years and examined at the Division of Oral Pathology of The Hebrew University. These cases represent 7.15% of the total number of biopsies (13508) during a fifteen-year period (1978-1992). Seven hundred and seventy six (776) biopsies (80.3%) represented inflammatory processes, cysts, pulp pathology and congenital malformations. The remaining 190 biopsies (19.7%) comprised neoplastic and tumor-like lesions: 18 (9.5%) were benign odontogenic neoplasms, 77 (40.5%) were benign non-odontogenic neoplasms, 18 (9.5%) were malignant tumors and the remaining 77 cases (40.5%) were tumor-like lesions.

Oral psoriasis: report of six new cases.

This article presents six cases of oral psoriasis originally diagnosed by means of the histological changes found on biopsies of the oral lesions. Three of the patients presented with oral and skin psoriasis. Of the remaining three, two presented with oral manifestations alone, although their follow-up was short, whilst the third showed delayed dermatological changes. Two of the cases were also complicated by psoriatic arthritis, one of them to the temporomandibular joint.

Ameloblastic fibrodentinoma: report on two new cases.

Brain heterotopia of the tongue is a rare, congenital malformation, probably not embryologically related to encephaloceles or to the so called "nasal gliomas." The progressive growth frequently noted confers to the lesion a tumor-like appearance and can raise a clinical suspicion of some rare neonatal neoplasia. The non-neoplastic nature of the lesion is well established, and the growth may well be due to the fact that heterotopic brain grows as rapidly as normal brain in the infant. Although local recurrence after incomplete resection has been reported, the clinical behavior of brain heterotopia of the tongue is benign.

Benign cementoblastoma. A review and five new cases.

This article includes five new cases of benign cementoblastoma. The study includes a review on 66 previously published cases that we consider to be bonafide cases. It is considered that benign cementoblastoma continues to be an infrequent entity that particularly affects young patients under the age of 30. The sex distribution shows a slight tendency for being more common in females. The most frequently effected area is the mandibular molar-premolar region. Pain, expansion and, radiographic radiopacity surrounded by a peripheral radiolucent halo are the most striking features. Treatment and prognosis are also discussed. Histopathologic conditions and factors to be considered with respect to differential diagnosis conclude the report.

Lichen planus: exploring its malignant potential.

Almost any area of the mouth may be affected by LP, but the most frequent locations are the cheeks, tongue and gingiva. The eight cases in our study illustrate the proliferative epithelial changes to verrucous or squamous cell carcinoma that can appear in oral LP. We also found a predisposition of LP in women. We urge, therefore, that clinicians monitor LP patients closely at three- to six-month intervals and attempt treatment for early resolution.

Photoacoustic injury and bone healing following 193nm excimer laser ablation.

The argon-fluoride excimer laser was investigated as a cutting-ablating tool for bone surgery. A total of 52 rats were divided into two experimental groups and two control groups. In one experimental group cortical bone defects were made; in another experimental group defects penetrating into the medullary space were performed. In the two control groups similar defects were achieved using water-cooled carbide burs. The rats were sacrificed on each of the 3, 7, 10, 20, 30, and 40 postoperative day. The cortical bone, the medullary space, and the extrabony tissue were examined by means of light microscopy. In both experimental groups, bone damage, represented by osteocyte destruction, extended to 1,050-1,450 microns ahead from the irradiated site, and bone healing was very much impaired. In the control groups no histological changes could be identified and bone healing appeared to be within normal limits. We believe this extensive bone damage, following 193 nm irradiation, to be a result of photoacoustic waves propagating in the bone following each pulse. In view of our results we feel that excimer lasers presently in use are not suitable for bone surgery. This problem of photoacoustic damage can be overcome in one of two ways: by designing a CW excimer laser or by reducing the pulse width to the picosecond regime.

Leukocytoclastic vasculitis (anaphylactoid purpura): a unique occurrence in the oral cavity.

Leukocytoclastic vasculitis, immune complex disorder (type III), is a skin disease with both an acute form characterized by bullae, vesicles and ulcerations, and a chronic form characterized by petechiae, macules and ulcerations. The disease presents certain systemic features including diffuse or focal glomerulonephritis and renal failure. The histopathologic characteristics of leukocytoclastic vasculitis in the skin appear primarily in small blood vessels and consist of an infiltration of inflammatory cells, leukoclasis, swelling of endothelial cells, occlusion of blood vessels, accumulation of fibrin and fibrinoid degeneration, as well as the presence of immune complexes in and around blood vessel walls. Although leukocytoclastic vasculitis is described as several diseases which can spread systemically, including the gastrointestinal tract and the kidneys, the manifestations of the disease in the oral cavity have not yet been reported. The present paper reports unique oral lesions in a 38-yr-old woman, diagnosed as leukocytoclastic vasculitis, without any accompanying skin or systemic lesions.

Gaucher's disease affecting the mandible and maxilla. Report of a case.

Gaucher's disease is a rare autosomal, recessive disorder characterized by deficiency of lyzosomal hydrolase glucocerebrosidase, and showing predilection for Ashkenazi Jews. A case of Gaucher's disease affecting both jaws and initially diagnosed by mandibular biopsy is described.

193 nm excimer laser ablation of bone.

The argon fluoride excimer laser is investigated as a cutting-ablating tool for bone surgery. Quantitative measurements are presented for various fluences of laser energy and number of pulses. Histological data are presented that demonstrate the minimal damage to the surrounding material from the laser interaction. Comparisons are made for non-decalcified and decalcified bone. The differences observed, as a function of decalcification in the fluences required for specified depth penetration, are noted and a possible explanation is suggested.

Squamous odontogenic tumor. Review of the literature and case report.

Squamous odontogenic tumor (SOT) is a rare, benign odontogenic tumor affecting both jaws in all age groups. The tumor is composed of squamous epithelial islands surrounded by a mature connective tissue stroma. This tumor may occasionally be misdiagnosed as ameloblastoma, squamous cell carcinoma, verrucous carcinoma and keratoacanthoma. A conservative surgical approach is the recommended treatment. An additional case is reported and the literature reviewed.

Osteogenesis in in vivo diffusion chamber cultures of human marrow cells.

The osteogenic diffusion chamber culture of rodent marrow cells is a well established system. In the present study, marrow cells from children and adult human donors were incubated in diffusion chambers implanted intraperitoneally in athymic mice. After 4 or 8 weeks, the chamber content was examined by light and electron microscopy. Child-cell cultures showed osteogenic tissue consisting of a mineralizing fibrous component and cartilage. Ultrastructurally, the fibrous tissue was similar to osteoid and exhibited osteoblast-like cells and mineralizing nodules. Mineral aggregates were also found in the cartilage. These features in child-cell chambers were similar to those found in control chambers of rabbit marrow cells. Adult-cell chambers showed only unmineralized fibrous tissue. These results render previous findings in animal-cell diffusion chamber systems relevant to the understanding of bone formation in man. It is suggested that the difference between child- and adult-cell chambers reflects an age-related decline in the number of marrow osteoprogenitor cells or their potential to undergo terminal osteogenic differentiation.

99mTc-MDP uptake and histological changes during rat bone marrow regeneration.

An established experimental model of tibial bone regeneration in rats was used in order to try to provide further information on the binding site of 99mTc-MDP, which is still not clearly defined. Four groups of rats on which surgical tibial bone marrow evacuation was performed and two control groups (nonoperated animals and sham-operated animals) underwent bone scan during the different stages of marrow regeneration; they were killed immediately after, and histological examination carried out. The correlation between the scintigraphic and the histological findings suggests that 99mTc-MDP binds primarily to calcification sites in young bone trabecules.

Chondromyxoid fibroma of the jaws: a clinicopathological study.

Chondromyxoid fibroma is a benign skeletal tumor which rarely affects the jaws. Only 10 cases have been found in the literature, all of them located in the mandible. In the present articles, 2 additional cases are described, one of them being the first reported case located in the maxilla. Up-to-date clinical and pathological data of 2 reported cases and a review of the literature are presented.

Dental abnormalities in aging sand rats (Psammomys obesus).

Sand rats transferred from their natural environment to laboratory conditions develop diabetes, cataracts, vertebral lesions, liver tumors, malocclusion and gingival inflammation. In the present study 43 sand rats of different ages were randomly chosen from a colony maintained for 13 years in the laboratory. Macroscopical, microscopical and radiographical examinations of the dental apparatus showed marked abnormalities in animals older than 6 months. The incisors were affected more than molars with an asymmetry between the right and left side of the jaw. Pathological alterations in the incisors included variations in length and curvature, lateral inclination, coronal fractures and pulpal calcifications. The enamel on the buccal aspect of these teeth had a scalloped appearance with corresponding metaplastic changes and folding of the ameloblastic layer. Coronal fractures were also found in molar teeth and were accompanied by marked hypercementosis. These changes are consistent with those reported in rodents with induced hormonal imbalance and may be associated with the diabetic state of aging sand rats. These gerbils are suggested as a model for studying the role of age-related disorders in the pathogenesis of certain dental abnormalities.

A study of a sample of oral cancer in Israel.

A review of data on oral cancer in Israel revealed a lower incidence and a later onset age than in other countries. These data are reviewed and consideration is given to the high prevalence of smoking and the low incidence of alcoholism in Israel.

Primary mineralization in the interface between bone and methyl methacrylate implants in rat mandibles. A correlative light and scanning and transmission electron microscope study.

Self curing polymethylmethacrylate implants were administered into rat mandibular bone. Tissue reaction was studied after different periods with light microscopy and transmission and scanning electron microscopy. Formation of fibrous tissue in the interface between implant and bone was associated with initial bone resorption and followed by the occurrence of primary calcification in a collagen rich matrix after 4-8 weeks. The features of primary mineralization comprised appearance of hydroxyapatite crystals within matrix vesicles and formation of calcospheritic structures. The occurrence of calcifying fronts after the intraosseous administration of polymethylmethacrylate suggests a favourable relationship between bone and the implant material.