Influence of dental education on adoption and integration of technological aids in the delivery of endodontic care by dental practitioners: a survey.

OBJECTIVE: To investigate adoption and integration of technological aids during endodontic treatment and where dental practitioners (DPs) learnt to use this technology. MATERIALS AND METHODS: An electronic questionnaire was distributed to all 459 dentists who graduated from University of Bergen between 2008 and 2018. The respondents were divided into two cohorts, older graduates (2008-2013) and newer graduates(2014-2018). RESULTS: A total of 314(68.4%) DPs answered the questionnaire. Magnification in the form of dental operating microscopes (DOM) and dental loupes was used by 180 (59.6%), electronic apex locators (EAL) by 271(89.7%) and motor-driven files by 281 (93.4%) DPs. The most frequent response, as to where they learnt to use them was: during undergraduate dental (UG) education. Significantly more newer graduates (90.7%) performed instrumentation based on what they learnt during UG education (p < .001). Older graduates based their instrumentation method equally on what they learnt during UG education (51.9%) and continuing dental education(42.6%). Rubber dam was used during all treatment procedures by 93% of the DPs. CONCLUSIONS: UG education is a communication channel with long-lasting importance for adoption and integration of technology by DPs. Exposure to innovations (awareness) during UG education is adequate for integration of technology. Continuing dental education is as valuable as UG education for adoption of technology for older graduates.

Characterization of the dental lymphatic system and identification of cells immunopositive to specific lymphatic markers.

The lymphatic system is important for immune barrier function and for tissue fluid balance. During inflammation, lymphangiogenesis takes place to enhance the transport of filtered fluid, proteins, and immune cells. Dental tissue is frequently exposed to inflammatory insults, but the lymphatic system and its responses to injury have not been investigated in detail using specific lymphatic markers. We aimed to study this system and to establish whether lymphangiogenesis takes place during wound healing. Immunostaining of the lymphatic endothelial hyaluronan receptor-1 (LYVE-1) and vascular endothelial growth factor receptor-3 (VEGFR-3) demonstrated initial lymphatics in the coronal molar pulp, whereas in incisors the initial lymphatics were found only in the apical part. In molars, lymphatic vessels exit the pulp through the apex and lateral canals. In interdental bone, transverse lymphatics were found, raising the possibility that an infection can be spread from the periodontal ligament to a neighbouring tooth. LYVE-1(+) and VEGFR-3(+) immune cells were found in both molar and incisor pulps, and phenotyping of the cells showed that they are of a monocytic lineage. In inflamed pulp these cells were not observed. Macrophages are suggested to contribute directly to the formation of lymphatic vessels after pulp exposure.

Sympathectomy suppresses tumor growth and alters gene-expression profiles in rat tongue cancer.

Sympathetic nerves are known to affect carcinogenesis. Recently we found that sympathetic denervation decreases the size of rat tongue tumors. To identify genes involved in rat tongue carcinogenesis and to study the effect of sympathetic nerves on these genes, we compared gene-expression profiles in normal rat tongue (control) and in tumor-induced tongues with (SCGx) and without (Sham) bilateral sympathectomy. Significance analysis of microarrays revealed 280 genes (168 up-regulated, 112 down-regulated) that showed at least a twofold differential expression between Sham and SCGx tumors (false discovery rate < 5%). These included genes associated with cell adhesion, signaling, structure, proliferation, metabolism, angiogenesis, development, and immunity. Hierarchical clustering demonstrated that controls and sympathectomized tumors grouped together, while Sham tumors grouped separately. We identified 34 genes, known to be involved in carcinogenesis, that were not differentially expressed between sympathectomized tumors and control tongues, but which showed a significant change in expression in Sham tumors. Microarray results of 12 of these genes were confirmed by quantitative reverse transcription-polymerase chain reaction. In conclusion, sympathectomy significantly altered the gene-expression profile and inhibited tumor growth. The expression of several cancer genes were increased more than threefold in Sham tumors, but unaltered in the sympathectomized tumors when compared with controls, indicating that these genes may be of significance in rat tongue carcinogenesis.

Identification of a Ca2+-sensing receptor in rat trigeminal ganglia, sensory axons, and tooth dental pulp.

Extracellular Ca2+ regulates dentin formation, but little information is available on this regulatory mechanism. We have previously reported that sensory denervation reduces dentin formation, suggesting a role for sensory nerves in tooth mineralization. The G protein-coupled Ca2+-sensing receptor (CaR) is expressed in dorsal root ganglia and perivascular sensory nerves in mesenteric arterioles, and activation of these receptors by Ca2+ has been shown to induce vascular relaxation. The present study determined CaR expression in tooth dental pulp (DP), sensory axons, and trigeminal ganglion (TG) as well as the effect of increased [Ca2+]e or a calcimimetic on tooth blood flow. The distribution of CaR, studied by immunochemistry, RT-PCR, and Western blot, indicates abundant expression of CaR in sensory axons in the jaws, TG, and DP. Restriction analysis of PCR products with specific endonucleases showed the presence of CaR message in TG and DP, and Western blotting indicates the expression of mature and immature forms of the receptor in these tissues. Pulpal blood flow, measured by laser-Doppler flowmetry, increased by 67% +/- 6% (n = 12) following receptor stimulation with 5 mM Ca2+, which was completely inhibited by 5 microM IBTx, a high-conductance KCa channel blocker indicating a mechanism involving hyperpolarization. NPS R-467 (10 microM) increased blood flow by 85% +/- 18% (n = 6), suggesting regulation through the CaR. Our results suggest that the CaR is present in sensory nerves, DP, and TG and that an increase in Ca2+ in the DP causes vasodilatation, which may contribute to accumulation of Ca2+ during dentin mineralization.

Effect of electrical tooth stimulation on blood flow and immunocompetent cells in rat dental pulp after sympathectomy.

Previous experiments show that nerves have effect on the emigration of immunocompetent cells during acute neurogenic inflammation. The present study aims to determine whether the sympathetic or sensory nerves are responsible for emigration of CD43+ and I-A antigen-expressing cells in the dental pulp after electrical tooth stimulation. Wistar rats were used. Experimental rats (n = 6) had the right superior cervical ganglion removed (SCGx), whereas control rats (n = 6) had sham surgery. Fourteen days later, electrical stimulation of the right maxillary 1st molar was performed in both groups for 20-25 s every 5th min for a total period of 4 h. Changes in pulpal blood flow (PBF) were recorded with a laser Doppler flowmeter. All rats were transcardiacally perfused and processed for immunohistochemistry using antibodies against neuropeptides and immune cells. Intermittent electrical stimulation consistently increased PBF and depleted sympathetic and sensory neuropeptides in the dental pulp. The increase in PBF gradually decreased and approached control values at the end of the 4 h stimulation period. A significant increase in the number of I-A antigen-expressing dendritic cells was found in both the SCGx (P < 0.001) and control rats (P < 0.007). In contrast, tooth stimulation did not increase the number of CD43+ cells in the SCGx rats compared to the unstimulated contralateral control molar. Significantly more CD43+ PMN cells (P < 0.01) were found in the control rats after stimulation. It is concluded that stimulation of sympathetic nerves causes recruitment of CD43+ PMN cells, whereas stimulation of sensory nerves causes emigration of I-A antigen-expressing dendritic cells in the dental pulp.