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At least 343 records · Page 19Linked to original sources
PubMed1993

Cosmetic oral and maxillofacial surgery: a new era.

Oral and maxillofacial surgery is a specialty of dentistry that may be likened to the proverbial "sleeping giant." From a humble, nascent beginning as a specialty to advance the then modern concept of alveolar surgery to its present state, oral and maxillofacial surgery is today vibrating with excitement. To the credit of dentistry, the profession now has a specialty that not only has the capability to alter the bony facial framework, but also can alter the collateral collagenous and superficial cutaneous structures. Combined with dental alteration of the dentition and gingival apparatus, the profession is nearing its zenith relative to having the capability of changing an entire face.

Adult↗
PubMed1996

Corrosion of amalgams under sliding wear.

OBJECTIVES: During mastication, dental amalgams are simultaneously subjected to corrosion by the oral environment and to a sliding-wear process by biting forces. In the present study, the effect of sliding wear on the corrosion behavior of two high-copper dental amalgams was investigated. METHODS: An experimental apparatus was utilized that allows electrochemical testing under sliding-wear conditions. Corrosion potential measurements and anodic polarization scans were conducted in 0.1 M NaCl solution under sliding wear to characterize the behavior of two commercial, high-copper, single composition dental amalgams. In addition, long duration tests were conducted to assess possible corrosion and wear synergistic effects. RESULTS: The results showed that sliding wear caused a sharp reduction in the corrosion potential, a significant increase in the corrosion rate and a decrease in the repassivation rate of both amalgams. These effects are due to the mechanical removal by the wear process of the surface protective film formed on dental amalgams. The simultaneous action of sliding wear and corrosion can also induce embrittlement that leads to cracking. SIGNIFICANCE: The present evidence suggests that this cracking may be one of the major contributors to marginal failures of dental amalgam restorations.

Copper↗
PubMed1996

Immunolocalization of the cation-independent mannose 6-phosphate receptor and cathepsin B in the enamel organ and alveolar bone of the rat incisor.

In order to examine our hypothesis that maturation ameloblasts could degrade the enamel matrix in a manner analogous to bone resorption mediated by osteoclasts, we have assessed the distribution of lysosomal enzymes in the enamel organ by immunolocalizing the cation-in-independent mannose 6-phosphate receptor (MPR) and the lysosomal enzyme cathepsin B at all stages of amelogenesis. Secretory ameloblasts showed strong immunoreactivity for MPR in the supranuclear Golgi region and in the cytoplasm between the Golgi region and the distal junctional complexes. However, cathepsin B immunoreactivity was mainly seen in the distal portion of Tomes' process, which was unreactive for MPR immunogenicity. In maturation ameloblasts, the MPR was observed on the ruffled border of the ruffle-ended ameloblast (RA) but not on the distal cell membrane of the smooth-ended ameloblast (SA), although both cell types demonstrated strong immunoreactivity for MPR in the Golgi region. Immunoreactive cathepsin B was seen at the distal ends of both RA and SA. It is postulated that the nascent lysosomal enzymes bind to the mannose 6-phosphate receptors which target them not only to intracellular lysosomes, but also to the ruffled border of maturation ameloblasts where these enzymes are secreted into the enamel. Since MPR and lysosomal enzymes were also detected on the ruffled border of osteoclasts (Ocl) adjacent to alveolar bone, our immunocytochemical approach provides strong evidence for a similarity between the maturation process in enamel, as mediated by the ruffle-ended maturation ameloblasts, and bone resorption mediated by osteoclasts. This study has established that a common mechanism, based on MPR-targeted lysosomal secretion and matrix degradation, is basic to the maturation process involved in calcified tissues as different as bone and enamel.

Alveolar Bone Loss↗
PubMed1984

Ultrastructural changes in the cementoblasts of rat molars after injection of vincristine.

Cytological changes in the cementoblasts of rats treated with vincristine were investigated. Accumulation of secretion granules indicated a disturbed secretory mechanism in the cells. Conspicuous dilation of the endoplasmic reticulum suggested disturbance in the transport of substances from the rough endoplasmic reticulum to the Golgi elements. These disturbances were interpreted to be a result of disruption of microtubules.

Animals↗
PubMed2000

Oral sensory papillae, chemo- and mechano-receptors, in the snake, Elaphe quadrivirgata. A light and electron microscopic study.

The oral sensory papillae of the snake (Elaphe quadrivirgata), comprising a compound sensory system located along the tooth rows, were studied by light microscopy, immunohistochemistry for neuron specific enolase and S 100 protein, and scanning and transmission electron microscopy. Each sensory papilla exhibited a single taste bud and free nerve endings in the epithelium, and Meissner-like corpuscles, branched coiled terminals, and lamellated corpuscles in the connective tissue. The taste buds consisted of four types of cells; the type III cells, exclusively synapsing onto intragemmal nerves, were identified as gustatory in function. The gustatory cells included dense-cored and clear vesicles in the cytoplasm. These vesicles were accumulated both in the presynaptic and infranuclear regions, suggesting dual functions: the synaptocrine and paracrine/endocrine release of signal substances. The free nerve endings constantly contained mitochondria and frequent clear vesicles. The Meissner-like corpuscles were located in the uppermost zone of the connective tissue. These corpuscles consisted of nerve fibers and lamellar cells. The nerve fibers, rich in mitochondria, were folded and layered on each other. The branched coiled terminals were localized in the connective tissue along the side wall of the papillae. Nerve fibers, free from a Schwann-cell covering, swelled up to make terminals which accumulated mitochondria and glycogen particles. The lamellated corpuscles were associated with the nerve-fiber bundles in the connective tissue. Consisting of a central nerve axon and lamellar cells encircling it, these corpuscles resembled mammalian Vater-Pacini corpuscles, except that they lacked a capsule. These findings demonstrated that the snake sensory papilla represents one of the most specialized, compound sensory systems among vertebrates, which may play an important role in receiving chemical and mechanical information on prey.

Animals↗