Enhancement by extracts of mineralized tissues of protein production by human gingival fibroblasts in vitro

Non-confluent cell cultures were exposed to both guanidine and guanidine-EDTA extracts of cementum, dentine and alveolar bone, at concentrations from 2 to 50 micrograms/ml for 48 h. The cells were radioactively labelled during the last 24 h. Total protein production was measured via incorporation of radioactive proline; collagen production was estimated by digestion of the radioactive protein mixture with bacterial collagenase. All guanidine-EDTA extracts elicited statistically-significant increases in total protein production when compared to controls. At 50 micrograms/ml of extract, the increase in protein production was 340, 143 and 338 per cent for bone, cementum and dentine, respectively. Similar results were obtained for collagen production. Guanidine-EDTA extracts also stimulated an increase in the production of specific proteins, as ascertained by gel electrophoresis. In contrast, the guanidine extracts had no effect on either protein or collagen production. Thus the functions of gingival fibroblasts can be altered by proteins from associated mineralized tissues. Identification of such proteins and their biological functions would enhance knowledge of the mechanisms that regulate connective-tissue regeneration.

Hormone-responsive cells derived from human dental papilla: characterization in vitro and in vivo in diffusion chambers

Cells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured in vitro through 3 to 7 passages. After exposure to prostaglandin E2 there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits. These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation.

Stimulation of mannose incorporation into rat osteoblastic osteosarcoma cells by parathyroid hormone

Agents considered to alter cAMP accumulation in bone cells were evaluated for their effects on protein production and sugar incorporation by bone cells. Total protein production or mannose incorporation by cells and in media were measured by the amount of radioactivity incorporated into trichloroacetic-acid precipitable fractions. Incorporation of radioactive leucine into the cellular and secreted proteins was linear over 5 h; radioactive mannose incorporation was linear only up to 2 h. Cells were also incubated with selected agents and radioactive mannose or leucine for 2 h. Addition of parathyroid hormone (PTH), isoproterenol or dibutyryl cAMP to osteoblasts resulted in a significant increase in mannose incorporation; dibutyryl cGMP and butyric acid had no effect on mannose incorporation. None of the agents altered total protein production. Thus PTH stimulates mannose incorporation into osteoblasts and this effect is, at least in part, modulated by cAMP.

Inflammatory cells and bacteria in pericoronal exudates from acute pericoronitis

The present work is one in a series of studies carried out to verify the relationship between bacteria and gingival tissues in pericoronitis. Exudates from 6 cases of acute pericoronitis were examined by light and electron microscopy, including ultrathin sections and negative staining. While bacterial phagocytosis was prevalent in all the exudates studied, spirochetes, which were the predominant microorganisms, were not observed being phagocytized by PMNs or macrophages. The presence of spirochetes in pericoronitis as compared with acute necrotizing ulcerative gingivitis is discussed.

Formation of calcifying matrix by osteosarcoma cells in diffusion chambers in vivo

The potential of clonal rat osteosarcoma (ROS) cell lines to form mineralized matrices was assessed in diffusion chambers in vivo. Diffusion chambers were inoculated with osteoblastic (ROS 17/2 and its subclone ROS 17/2.8) and non-osteoblastic (ROS 24/1) clonal lines and implanted either intraperitoneally into athymic mice or subcutaneously into syngeneic ACI rats. Control chamber cultures of rabbit marrow or spleen cells were also incubated in athymic mice. Light and electron microscopy of chambers with ROS 17/2 and ROS 17/2.8 cells revealed production of mineralized matrices typical of osteosarcoma and characterized by abundance of collagen fibrils and associated mineralizing nodules. ROS 24/1 cells produced similar collagenous matrices, but these were devoid of mineral. The present experiments, carried out independently in two different laboratories, demonstrate the potential of ROS cells to produce a mineralized matrix. This corroborates previous studies on other osteoblastic features of these cell lines.

Pericoronitis: a reappraisal of its clinical and microbiologic aspects

Pericoronitis is an infectious disease of the operculum overlying an erupting or semi-impacted tooth. It manifests itself mainly in late adolescence and young adulthood and nearly always occurs around the lower third molar. The distinctive location, age, clinical picture, and link with predisposing factors warranted a reappraisal of pericoronitis and its etiology. Spirochetes and fusobacteria proved prevalent at all stages of the disease. The presence of these microbacteria may provide a clue as to the late appearance, particular location, and singular clinical picture of pericoronitis. The fact that spirochetes and fusobacteria are also found in acute necrotizing ulcerative gingivitis, and have been associated with alveolar osteitis, indicates a possible relationship between these disorders and pericoronitis.

Salivary calculi: ultrastructural morphology and bacterial etiology

Ultrastructural morphology of 16 salivary calculi was studied by means of transmission and scanning electron microscopy. The external surface was mostly globular or coarse, and on high magnifications and features could be divided into four main groups: a) amorphic calcified deposits covering extensive areas, b) other areas covered with crystals in a variety of arrangements, c) heavy accumulations of calcified rod-like and filamentouslike microorganisms, and d) platelet crystals in juxtaposition to calcified microorganisms in several areas. In most calculi the split area was found to be laminated. It is suggested that microorganisms have an important role in the formation and growth of salivary calculi.

Odontoma in the subcondylar region

An instance of a compound odontoma in the condylar process in a 24-year-old female is described. Location of odontomas in the coronoid or condylar processes were not reported. A hypothesis of migration of the third molar bud into the condylar region, an interfering local factor such as trauma or infection are suggested as aetiologic factors to the tumour in this case. Pre-operative radiographic localisation of the mass, are essential for treatment planning. An intra-oral approach was the treatment of choice.

Lymphosarcoma of the mandible associated with macroglobulinemia of Waldenström

Waldenström macroglobulinemia is a rare progressive immunoproliferative disorder involving lymphocytes and occasionally plasma cells. Unlike the multiple myeloma, this disease has minimal osseous lesions. Lesions in the jaws are very rare. This paper presents a case of lymphosarcoma in the mandible in a 68-year-old woman, who was diagnosed as suffering from Waldenström macroglobulinemia. The possibility of immunosuppression by Leukeran as an aetiologic factor causing the bone lesions is suggested.

The mural ameloblastoma: a review of the literature

Mural ameloblastomas are estimated to constitute 5% of all ameloblastomas. Although resembling the total ameloblastoma population in terms of predilections for sex and site, the average age of the patients with mural ameloblastoma, in comparison with the total group, was 21.8 vs 38.9 years. Eighty-five percent of the mural ameloblastomas were associated with follicular cysts, all of which were observed before the age of 30. The frequency of recurrence after simple enucleation of the cyst containing this lesion is considerably lower than that for ameloblastomas in general that are treated in a similar manner. Therefore, further and more extensive surgery for mural ameloblastoma is justified only in the event of recurrence.

The basal cell nevus syndrome associated with cleft lip and cleft palate: report of case

A case of basal cell nevus syndrome with multiple keratocysts, cleft lip and cleft palate, calcification of the falx cerebri, and late appearance of basal cell carcinoma is described.

Resorption of the crown in impacted maxillary canine. A clinical, radiographic and histologic study

Thirty-six maxillary impacted canines which showed coronary resorption were selected out of 252 impacted canines. Clinical, radiographic and histologic observations were performed. In the majority of the cases (31) a local inflammatory factor was present and only in five cases was the resorption idiopathic. The incidence of resorption was highest in the later decades of life. In all cases bone replacement was found.

Modification of the muco-periosteal flap design in anterior maxillary osteotomies

A modification of the mucoperiosteal flap planning for anterior maxillary osteotomy operations is suggested. This approach involves a total reflection of the labial mucoperiosteal flap, with the advantages of direct vision of the operative field thus providing easy and precise execution of the operative bony cuts, avoiding damage to the adjacent teeth and reduction of operating time. Sufficient blood supply to the mobilised segment is maintained through the palatal blood vessels. Corrective periodontal surgery may also be carried out at the same time.

Median mandibular cyst

Since the median mandibular cyst is an extremely rare lesion, there is difficulty in determining the nature and origin of this entity. An additional case of a median mandibular cyst is described and an attempt is made to clarify the confusion associated with the diagnosis of this lesion. After a review of the literature it is suggested that the median mandibular cyst is a much rarer entity than was previously believed.

Effect of local application of fluoride on healing of experimental bone fractures in rabbits

The effect of local application of low fluoride concentrations on the healing of experimental bone-radii fractures in 20 rabbits was examined. No external fixation was required after the osteotomy and gelfoam being used as a medium for fluoride application. Histologic mineral and mechanical strength measurements were carried out on the healing callus. There were no significant changes in the ashpercentage and the fluoride concentration of the ash between the experimental and control callus. A significantly higher percentage of ossified tissue was found in the fluoride treated callus. The breaking strength was found to be significantly higher in the bone fractures treated with fluoride, whereas there was no notable difference between the surface areas. It is postulated that the greater amount of ossified tissues, the differences in organization of the bone trabecules, and/or an improved mineral crystallinity may be responsible for this result.

The effect of long standing chronic mechanical irritation on the tongue of rats

The effect of long standing mechanical irritation of the tongue was studied in 100 young rats. This was effected by the protruding end of a twisted wire, ligated around the lower first molar and directed toward the later-ventral aspect of the tongue on one side, while the other side served as control. Groups of rats were killed after 3, 6, 9 and 12 months and the tongues were examined grossly and microscopically. Fibrous hyperplasia was observed in 48% of tongues in the 3-month group and increased to 79% in the 12-month group. Microscopically, epithelial changes were noted which included ulceration acanthosis and hyperkeratosis. In no instance was dyskeratosis or any other malignant change noted.

Scanning electron microscopy of dental calculus

The morphologic structure of anorganic dental calculus was studied by means of the scanning electron microscope. From surface observations, calculus is apparently composed of two components with distinguishable patters of calcification. One component is formed by the precipitation of minute calcific crystals on microorganisms and intermicrobial substances (plaque matrix). Such calcified masses, often spherical in shape, have a sponge-like appearance with empty spaces representing the former sites of entombed and degenerated organisms. Thus, intracellular calcification is not evident at this stage of calculus development. The other component, although having at least one common calcification front with the former, does not appear to be directly associated with microbial calcification. It exhibits a configuration of generally larger crystal growths of varying shapes and sizes. These two calcification patterns are comparable, both in distribution and size, to what has been observed by means of the transmission electron microscope, and what Schroeder has designated as "types A & B centers of mineralization," respectively. The calcific precipitation in type A centers have been identified by X-ray diffraction as hydroxyapatite. It is, therefore, speculated that the crystal patters in type B centers might represent other known forms of calcium phosphates present in calculus, such as octacalcium phosphate, whitlockite and brushite.