Enhanced Learning During The Dental Hygiene Process Of Care
[New York NY : NYU College of Dentistry. NYU Academy of Distinguished Educators], 2015
Current status of periodontal risk assessment
Chronic periodontitis is a destructive chronic inflammatory disease of bacterial etiology. Mounting evidence confirms that not all patients are susceptible to inflammatory periodontal disease, and further, that the extent and severity of its clinical manifestation varies as a function of individual risk. Risk assessment models are needed to target treatment effectively. Contemporary risk assessment, as applied to periodontal disease, represents an innovative approach to managing periodontitis. The central intent of this paper is to review the current view of risk assessment as it relates to the diagnosis and management of chronic periodontitis, as well as to consider a number of such applications that can be incorporated into daily practice.
The potential use of gingival crevicular blood for measuring glucose to screen for diabetes: an examination based on characteristics of the blood collection site
BACKGROUND: This study examined conditions under which gingival crevicular blood (GCB) could be used to obtain a useful glucose reading to screen for undiagnosed diabetes during routine dental visits. METHODS: GCB and capillary finger-stick blood (CFB) glucose readings obtained with a glucometer were compared for 46 patients recruited from an urban university dental clinic. Study participants were divided into two groups based on probing depth or bleeding on probing (BOP) at the site of collection of the GCB sample. Group 1 participants had blood collected from sites with adequate BOP to obtain a sample without touching the tooth or gingival margin, whereas group 2 participants had blood collected from sites with little or no bleeding. For each group, Pearson correlations were calculated for glucose readings obtained using GCB and CFB samples, and the limits of agreement between the two samples were examined. RESULTS: For group 1 participants, correlations between CFB and GCB glucose readings were high (0.89), and the limits of agreement were acceptable (-27.1 to 29.7). By contrast, for participants in group 2, correlations between the glucose readings were lower (0.78), and limits of agreement were much broader (-25.1 to 80.5). CONCLUSION: GCB samples were suitable to screen for diabetes in persons with sufficient BOP to obtain a sample without touching the tooth or gingival margin (i.e., in patients having the basic clinical signs of gingivitis or periodontal disease).
Ca(2+) influx through the osteoclastic plasma membrane ryanodine receptor
We predict that the type 2 ryanodine receptor isoform (RyR-2) located in the osteoclastic membrane functions as a Ca(2+) influx channel and as a divalent cation (Ca(2+)) sensor. Cytosolic Ca(2+) measurements revealed Ca(2+) influx in osteoclasts at depolarized membrane potentials. The cytosolic Ca(2+) change was, as expected, not seen in Ca(2+)-free medium and was blocked by the RyR modulator ryanodine. In contrast, at basal membrane potentials (approximately 25 mV) ryanodine triggered extracellular Ca(2+) influx that was blocked by Ni(2+). In parallel, single-channel recordings obtained from inside-out excised patches revealed a divalent cation-selective approximately 60-pS conductance in symmetric solutions of Ba-aspartate [Ba-Asp; reversal potential (E(rev)) approximately 0 mV]. In the presence of a Ba(2+) gradient, i.e., with Ba-Asp in the pipette and Na-Asp in the bath, channel conductance increased to approximately 120 pS and E(rev) shifted to 21 mV. The conductance was tentatively classified as a RyR-gated Ca(2+) channel as it displayed characteristic metastable states and was sensitive to ruthenium red and a specific anti-RyR antibody, Ab(34). To demonstrate that extracellular Ca(2+) sensing occurred at the osteoclastic surface rather than intracellularly, we performed protease protection assays using pronase. Preincubation with pronase resulted in markedly attenuated cytosolic Ca(2+) signals triggered by either Ni(2+) (5 mM) or Cd(2+) (50 microM). Finally, intracellular application of antiserum Ab(34) potently inhibited divalent cation sensing. Together, these results strongly suggest the existence of 1) a membrane-resident Ca(2+) influx channel sensitive to RyR modulators; 2) an extracellular, as opposed to intracellular, divalent cation activation site; and 3) a cytosolic CaM-binding regulatory site for RyR. It is likely therefore that the surface RyR-2 not only gates Ca(2+) influx but also functions as a sensor for extracellular divalent cations
In vitro osteoblastic and odontoblastic activities on calcium phosphates and substituted apatites [Meeting Abstract]
Identification and characterization of a sodium/calcium exchanger, NCX-1, in osteoclasts and its role in bone resorption
We provide the first demonstration for a Na+/Ca2+ exchanger, NCX-1, in the osteoclast. We speculate that by using Na+ exchange, NCX-1 couples H+ extrusion with Ca2+ fluxes during bone resorption. Microspectrofluorimetry of fura-2-loaded osteoclasts revealed a rapid and sustained, but reversible, cytosolic Ca2+ elevation upon Na+ withdrawal. This elevation was abolished by the cytosolic introduction (by gentle permeabilization) of a highly specific Na+/Ca2+ exchange inhibitor peptide, XIP, but not its inactive analogue, sXIP. Confocal microscopy revealed intense plasma membrane immunofluorescence with an isoform-specific monoclonal anti-NCX-1 antibody applied to gently permeabilized osteoclasts. Electrophysiological studies using excised outside-in membrane patches showed a low-conductance, Na+-selective, dichlorobenzamil-sensitive, amiloride-insensitive channel that we tentatively assigned as being an NCX. Finally, to examine for physiological relevance, an osteoclast resorption (pit) assay was performed. There was a dramatic reduction of bone resorption following NCX-1 inhibition by dichlorobenzamil and XIP (but not with S-XIP). Together, the results suggest that a functional NCX, likely NCX-1, is involved in the regulation of osteoclast cytosolic Ca2+ and bone resorption.
Calcium channel current in rat dental pulp cells
Voltage-gated Ca(2+) currents in early-passage rat dental pulp cells were studied using whole-cell patch-clamp techniques. With Ba(2+) as the charge carrier, two prominent inwardly-directed currents, I(f) and I(s), were identified in these cells that could be distinguished on the basis of both kinetics and pharmacology. I(f) was activated by membrane depolarizations more positive than -30 mV, and displayed fast inactivation kinetics, while I(s) was activated by steeper depolarizations and inactivated more slowly. At peak current, time constants of inactivation for I(f) and I(s) were approximately 17 vs. approximately 631 msec. Both I(f) and I(s) could be blocked by lanthanum. By contrast, only I(s) was sensitive to either Bay-K or nifedipine, a specific agonist and antagonist, respectively, of L-type Ca(2+) channels. I(s) was also blocked by the peptide omega-Conotoxin GVIA. Taken together, results suggested that I(f) was mediated by divalent cation flow through voltage-gated T-type Ca(2+) channels, whereas I(s) was mediated by L- and N-type Ca(2+) channels in the pulp cell membrane. The expression of these prominent, voltage-gated Ca(2+) channels in a presumptive mineral-inductive phenotype suggests a functional significance vis a vis differentiation of dental pulp cells for the expression and secretion of matrix proteins, and/or formation of reparative dentin itself
Amyloid beta-peptide alters calcium channels in neuroblastoma cell lines: A possible neurotoxic mechanism in Alzheimer's disease [Meeting Abstract]
A novel method to isolate odontoblasts from rat incisor
Historically, odontoblasts have been isolated from rat incisor using a surgical curette to separate these cells from the dentin. Isolation of odontoblasts using this approach typically resulted in cells with membrane properties that made the application of patch-clamp electrophysiological techniques prohibitive. The studies here describe a new procedure for isolating mature odontoblasts from adult rat incisor to obtain enriched populations of intact, viable odontoblasts that can be readily studied using patch-clamp methodologies. Identification of isolated cells as odontoblasts was confirmed using in situ mRNA hybridization for expression of dentin sialoprotein, osteocalcin, bone sialoprotein, and type I collagen, and calcium flux was monitored in these cells by means of fura-2 microfluorometry. We suggest that either single odontoblasts or clusters of these cells isolated by this new method would be an ideal preparation for the study of odontoblast properties using electrophysiological techniques, in situ hybridization and/or microfluorometry
Effect of low-density lipoprotein (LDL) an intracellular calcium in rat pulp fibroblasts [Meeting Abstract]