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The present study compared the alkaline phosphatase (ALPase) expression and DNA content at specific periods in cultured cells derived from non-inflamed enlarged gingivae of idiopathic gingivofibromatosis (IGF) and phenytoin-induced hyperplasia (PHG). Cultured cells from healthy gingiva or periodontal ligament (PDL) were used as controls. The DNA assay, ALPase assay and cytochemical staining for ALPase in cultured cells were performed at four, seven, and nine days. The presence of intense ALPase activity was a prominent feature in cultured IGF cells, whereas very low ALPase activity was detected in PHG cells. The cell lines tested showed no significant differences in DNA content. The expression of ALPase in these cells was population density-dependent. The observation that cells isolated from both types of gingival overgrowth exhibited a different ALPase profile at variance with normal gingival fibroblasts suggested that a distinct pathogenic mechanism may be involved in each type of gingival overgrowth.

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Fibroblast heterogeneity in human periodontal tissues was characterized by cloning and immuno-histochemical techniques. Cell suspensions from primary cultures gingival (GF) and PDL fibroblasts (PF) were cloned. The relative intensity of double-labeled immunofluorescence, using specific antibodies to the extracellular matrix (ECM) molecules collagen type I (CI), type III (CIII), and fibronectin (Fn), was measured by photometry. Most clones derived from either GF or PF showed positive intracellular staining for both CI and Fn, and CIII and Fn. However, there were variations in fluorescence intensity for CI and Fn, ranging from relatively weak to strongly positive. The fluorescence for CI and CIII was relatively weak in most isolated GF clones in contrast to their PF clones. These observations coupled with studies of growth and cellular morphology in individual clones suggest that: 1) GF and PF contain functionally heterogeneous subpopulations; and 2) the synthesis and expression of extracellular matrix molecules of GF may be essentially different from that of PF.

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A model system involving co-cultures of human gingival or periodontal ligament fibroblasts with mouse epithelial root sheath cells or human gingival epithelial cells was used to study epithelial cell-fibroblast interactions. Double-labeled immunofluorescence and microfluorometry were used to investigate the expression of extracellular matrix molecules of collagen type I (collagen I), type III (collagen III) and fibronectin in fibroblasts. When fibroblasts from either source were cultured alone, the fluorescence for collagen I and fibronectin ranged from strongly positive to almost negative. Collagen III staining was relatively weak compared with that of collagen I. After 2-3 days of co-culture, gingival fibroblasts and ligament fibroblasts adjacent to the mouse sheath cells exhibited enhanced intracellular fluorescence for collagen I and fibronectin. Very little change was observed for collagen III. Gingival fibroblasts cultured with gingival epithelial cells showed increased fluorescence for collagen I but decreased fluorescence for fibronectin. In contrast, the fluorescence intensity for both collagen I and fibronectin in ligament fibroblasts were reduced after 3 days of co-culture with gingival epithelial cells. Ultrastructural changes in fibroblasts co-cultured with mouse root sheath cells included increased Golgi cisternae and vesicles and an increased abundance of rough endoplasmic reticulum, polyribosomes, secretory vesicles and pinocytotic vesicles. Thus, the expression of extracellular matrix proteins and the metabolic activity of fibroblasts can be modulated by oral epithelial cells.

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Interactions between epithelial cells and fibroblast clones were examined to determine whether various fibroblasts clones derived from gingival or periodontal tissues responded differently to oral epithelial cells. We provide evidence that epithelial root sheath (ERS) cells enhanced collagen type I (CI) expression in most periodontal clones, whereas ERS cells variably influenced CI expression of gingival fibroblast clones. Modulation of collagen type III (CIII) expression in both gingival and periodontal clones by ERS cells was less in magnitude and mostly suppressive in gingival clones. Fibronectin (Fn) expression in many gingival and periodontal clones was decreased in cells associated with ERS cells. On the other hand, the influence of gingival epithelial cells on fibroblast clones tended to be inhibitory, especially in periodontal clones. Thus, gingival epithelial (GE) cells suppressed the expression of collagen types I and III and Fn in most periodontal clones. Except for suppression of Fn expression, GE cells had less influence on CI and CIII expression in gingival clones. The modulations of fibroblast extracellular matrix components by ERS and GE have profound implications for the regulation of the development, repair and regeneration of the periodontal tissues.

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Masseter muscle silent periods were assessed in 24 children divided into three groups according to their stage of dental development (primary, mixed, and permanent). Surface electrode EMG data, timing code, and microphone input were recorded on magnetic tape. A visual record was obtained by playing the tape into an optical oscillograph; measurements were made from the photosensitive paper. The results indicate the latency and silent period durations of clenched jaw jerks were similar among the three groups. For the subjects in this study, the mean latency and silent period durations of the masseter muscle during clenched jaw jerks were 14.9 ms (milli-seconds) and 27.0 ms.

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The results of this study indicate that the latency and silent periods of OCC cycles do not vary among groups representing distinct dentitional stages. The mean latency period durations obtained from the OCC cycles of the subjects in this study ranged from 16.6 to 19.5 msec and demonstrated the smallest SD of all parameters measured. The mean silent period durations ranged from 11.6 to 15.4 msec. Since the neurophysiologic responses do not vary, the reflex elicited by tooth contact in OCC cycles is not based on tooth form or quantity. The results further indicate that, with the exception of the latency period of the anterior temporal muscles, the activities of the right and left components of the masticatory muscles examined are significantly correlated to each other during OCC cycles. This suggests a role for the anterior temporal muscle in bringing about adjustments of the masticatory system in the intercuspal position.

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Electromyographic analysis was carried out prior to occlusal equilibration for patients who had some form of TMJ dysfunction and again after treatment. The results were compared with similar analyses for patients without any symptoms of dysfunction (controls) and for patients who had been wearing some kind of occlusal appliance as treatment for dysfunction. The parameters measured were the period of minimal activity (inactive phase of jaw elevators sometimes referred to as the inactive phase), the duration of muscle contraction before tooth contact (DMC), the period of muscle activity after tooth contact (latency), the inhibitory response, and the duration of the clench phase of the temporal and masseter muscles. In general the pathological series had longer cycles, longer DMC, longer clench phases and less significant correlation coefficients than the controls. The results indicated a dominance of the closing muscles in the pathological groups over the other parameters of the cycle during metronome monitoring. Also, the controls and the POST equilibration group yielded readily to cortical command. The parameters of the cycle in the POST-equilibration group were facilitated as compared to the other groups.

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Dipyridyl inhibits the morphogenesis of tooth germs, but the germs recover when transferred to control medium. In this study, the effect of dipyridyl on basement membrane was investigated in vitro. The basal lamina was always present, but the subjacent collagen fibrils disappeared in the presence of dipyridyl and reappeared during recovery in control medium.

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Clonal cell lines from the dermis of a dermatosparaxic calf were grown in tissue culture. After fixation in a mixture of glutaraldehyde and osmium, they were prepared for electron microscopy. Most cells contained a well-developed Golgi region, lysosomes, mitochondria, and dilated cisternae of rough endoplasmic reticulum. They also contained numerous, large bundles of intracellular fialments, many lipid droplets and extensive arrays of vesicles. Cultures accumulated substantial amounts of extracellular fibrillar material. The fibrils were loosely packed and indistinctly cross-banded. Bundles of intracellular filaments were commonly parallel in adjacent cells and also parallel to extracellular fibrils. These cytoplasmic features may result from the inability of the secreted collagen to form normal fibrils.

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A population of procollagen molecules has been isolated from the culture medium of a clonal line of calf dermatosparactic cells and shown to have the amino-acid composition, physical properties, and molecular structure consistent with collagen precursors. Although this procollagen population shares immunologic determinants with the procollagen obtained from dermatosparactic skin, it differs from the latter in aminoacid composition, in subunit properties, and by its content of both amino and carboxyl terminal non-collagen peptide appendages. We propose that the cell culture procollagen contains earlier biosynthetic forms of dermatosparactic procollagen.

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