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1.  Pathways of fear and anxiety in dentistry: A review 
The aim of this article was to analyze the theories underpinning dental fear, anxiety and phobias. To be included, articles must have been published between the years of 1949 and 2013 concerning fears and phobias within dentistry and/or psychiatry. Of 200 articles originally under review, 140 were included and reviewed by the authors.Five specific pathways relating to dental fear and anxiety were identified; Cognitive Conditioning, Informative, Visual Vicarious, Verbal Threat, and Parental. Eight currently accepted management techniques across all dental disciplines for dental fear and anxiety were identified. Further research is required to identify clinical diagnosis and treatment for fears originating from different pathways.
PMCID: PMC4233415  PMID: 25405187
Dentistry; Fear and anxiety; Phobia; Origin; Therapies and management
2.  IL-17 Receptor A Signaling Is Protective In Infection-Stimulated Periapical Bone Destruction 
IL-17 is a pleiotropic cytokine produced by Th17 T cells that induces a myriad of proinflammatory mediators. However, different models of inflammation report opposite functional roles of IL-17 signal in terms of its effects on bone destruction. In the present study we determined the role of IL-17 receptor A (RA) signal in bone resorption stimulated by dentoalveolar infections. Infrabony resorptive lesions were induced by surgical pulp exposure and microbial infection of mouse molar teeth. IL-17 was strongly induced in periapical tissues in wild-type (WT) mice by 7 days after the infection but was not expressed in uninfected mice. Dentoalveolar infections of IL-17RA knockout (KO) mice demonstrated significantly increased bone destruction and more abscess formation in the apical area compared to WT mice. Infected IL-17RA KO mice exhibited significantly increased neutrophils and macrophages compared to the WT littermates at day 21, suggesting a failure of transition from acute to chronic inflammation in the IL-17RA KO mice. The expression of IL-1 (both α and β isoforms) and MIP2 were significantly up-regulated in the IL-17RA KO compared to WT mice at day 21 post infection. The development of periapical lesion in IL-17RA KO mice was significantly attenuated by neutralization of IL-1β and MIP2. Taken together, these results demonstrate that IL-17RA signal seems to be protective against infection-induced periapical inflammation and bone destruction via suppression of neutrophil and mononuclear inflammation.
PMCID: PMC3767040  PMID: 23863904
3.  Perceived quality, clarity, and accuracy of manually processed and self-developing radiographs in endodontics 
To evaluate perceived quality, clarity, and accuracy of self-developing films compared to conventional D- and E-speed manually processed films, and to evaluate their ease of use and satisfaction amongst pre-clinical dental students.
Mesiobuccal root canals of 30 extracted mandibular molar teeth were instrumented and size 10 K-files were glued into the canals at 3 different levels. Each tooth was exposed thrice with the same angulation using conventional E-speed, D-speed, and self-developing films. Conventional films were processed manually and self-developing films according to the manufacturer’s instructions, which required 50 seconds of contact time with the solution. Radiographs were evaluated by 4 examiners for quality, clarity, and apical position of the file. A questionnaire-based survey was conducted to evaluate the ease of use, quality, and satisfaction of undergraduate students. Data were analyzed using one-way ANOVA and Tukey–Kramer multiple comparison test, significant at p < 0.05.
The quality and clarity of conventional E-speed films was perceived as significantly better than that of D-speed and self-developing films (p < 0.05). There was no statistically significant difference amongst the 3 film types for recorded file positions (p > 0.05). The results of the student survey corroborated the examiners’ views that the self-developing radiographic films were of poor quality.
Manually processed E-speed films provided significantly superior quality and clarity of images, but for apical file position, no significant differences were found amongst the 3 film types. Conventional E-speed, D-speed, and self-developing films are all adequate for measuring endodontic working lengths.
PMCID: PMC3883600  PMID: 24421739
4.  Bacteria-reactive immune response may induce RANKL-expressing T-cells in the mouse periapical bone loss lesion 
Journal of Endodontics  2012;38(3):346-350.
The present study investigated if T-cells infiltrating the periapical lesion produce RANKL and whether bacteria infecting the root canal can activate T-cells to produce RANKL.
Using a mouse model of periapical lesion induced by artificial dental pulp exposure, the presence of RANKL-positive T-cells and osteoclasts in the periapical lesion was examined by an immuno-histochemical approach. The bacteria colonizing the exposed root canal were identified by 16S ribosomal RNA (rRNA) sequence analysis. The isolated endodontic bacteria were further immunized to normal mice, and sRANKL production by the T-cells isolated from the immunized mice was evaluated by ex vivo culture system.
RANKL-positive T-cells, along with TARP+ osteoclasts, were identified in periapical bone resorption lesions. The Gram-negative bacterium Pasterurella pnumotropica (P. pnumotropica), which was most frequently detected from root canal of exposed pulp, showed remarkably elevated serum IgG antibody response in pulp-exposed mice compared to control non-treated mice. Immunization of mice with P. pneumotropica induced not only serum IgG antibody but also primed bacteria reactive T-cells that produced sRANKL in response to ex vivo exposure to P. pneumotropica.
T-cells infiltrating the periapical region express RANKL, and the endodontic bacteria colonizing the root canal appear to induce RANKL expression from bacteria-reactive T-cells, suggesting the possible pathogenic engagement of immune response to endodontic bacteria in the context of developing boneresorptive periapical lesions.
PMCID: PMC3291477  PMID: 22341072
5.  The Uptake of Nickel-Titanium Rotary Files in Saudi Arabia 
Aim. We surveyed the uptake of nickel-titanium rotary files (NTRFs) among all dentists in Saudi Arabia. Methodology. A questionnaire encompassing endodontic performance and NTRF uptake was e-mailed to all members of the Saudi Dental Society. Data were collected from participants during a three-month period and were analyzed using χ2 tests and correlation coefficients. Level of significance was set at P = 0.05. Results. The overall response rate was 30.6% (n = 490), and 82.9% were found to perform root canal treatment (RCT). Among the 406 RCT performers, general dentists formed the bulk (45%). Among endodontists, 91.5% were using NTRF (P < 0.001). Those who graduated between 1991 and 2000 used NTRF more than any other group did (78.4%, P = 0.05). Graduates from Europe and Australia used NTRF most frequently (100%, P = 0.001), followed by those from North America (87%, P = 0.001), and finally by Saudi Arabian graduates (68.7%). Male respondents performed more endodontic procedures and used NTRF significantly more often than female respondents did (males: 73%; females: 56.2%) (P = 0.001). The most significant reasons for not using NTRF were “unavailability” (64.7%, P ≤ 0.05) and “lack of experience” (54.1%, P ≤ 0.001). Conclusions. We found that NTRF usage was not as widespread in Saudi Arabia as in other developing countries. Therefore, we suggest an improved implementation of NTRF in undergraduate and postgraduate curriculums and the provision of educational courses with a greater focus on this development.
PMCID: PMC3332188  PMID: 22567009
6.  18beta-Glycyrrhetinic Acid Inhibits Periodontitis Via Glucocorticoid-Independent NF–κB Inactivation In IL-10 Deficient Mice 
Journal of periodontal research  2010;45(6):757-763.
Background and objective
18beta-glycyrrhetinic acid (GA) is a natural anti-inflammatory compound derived from licorice root extract (Glycyrrhiza glabra). The effect of GA on experimental periodontitis and its mechanism of action were determined in the present study.
Periodontitis was induced by oral infection with Porphyromonas gingivalis W83 in IL-10 deficient mice. The effect of GA, which was delivered by subcutaneous injections in either prophylactic or therapeutic regimens, on alveolar bone loss and gingival gene expressions was determined on day 42 after initial infection. The effect of GA on LPS-stimulated macrophages, T cell proliferation, and osteoclastogenesis was also examined in vitro.
GA administered either prophylactically or therapeutically dramatically reduced infection-induced bone loss in IL-10 deficient mice, which are highly disease-susceptible. Although GA has been reported to exert its anti-inflammatory activity via down-regulation of 11-beta hydroxysteroid dehydrogenase-2 (HSD2), which converts active glucocorticoids (GC) to their inactive forms, GA did not reduce HSD2 gene expression in gingival tissue. Rather, under GC-free conditions, GA potently inhibited LPS-stimulated proinflammatory cytokine production and RANKL-stimulated osteoclastogenesis, both of which are NF–κB-dependent. GA furthermore suppressed LPS- and RANKL-stimulated phosphorylation of NF–κB p105 in vitro.
These findings indicate that GA inhibits periodontitis by inactivation of NF–κB in an IL-10 and GC-independent fashion.
PMCID: PMC3075584  PMID: 20682015
18beta-glycyrrhetinic acid; periodontal disease; NF–κB; IL-10 deficient mouse
7.  Regulatory T cells in Mouse Periapical Lesions 
Journal of endodontics  2009;35(9):1229-1233.
T regulatory (Treg; CD4+FOXP3+) cells constitute a unique subpopulation of CD4+ T cells that inhibit T cell responses and prevent disease development/exacerbation in models of autoimmunity. In the present study, we tested the hypothesis that Treg cells are induced in periapical lesions by dental pulp infection.
In situ hybridization (ISH) was used to localize FOXP3+ cells on day 21 after pulp exposure of the 1st molar teeth and infection with bacteria from the oral environment. FOXP3/GFP knock-in transgenic mice were used to quantify FOXP3+Treg cells that infiltrate into periapical lesions by flow cytometry on days 7, 14, and 21 after infection. Periodontal ligament from uninfected teeth served as a negative control.
ISH showed strong signals that demonstrated the presence of FOXP3+ cells mainly at the periphery of periapical lesions. In contrast no positive cells were present in the periodontal ligament of uninfected controls. Flow cytometry demonstrated an increase in the number of FOXP3+ Treg beginning between day 7 and day 14 (0.69% of the infiltrate) after infection, and increased to day 21 (0.94%) (p<0.05, p<0.001 respectively vs. uninfected controls). Treg were also increased in number in draining cervical lymph nodes following pulpal infection.
These results demonstrate that Treg cells are induced to infiltrate into periapical lesions by pulpal infection, and suggest that they increase in a time-dependent manner.
PMCID: PMC2778286  PMID: 19720221
T regulatory cells; periapical lesions; pulp infection; FOXP3/GFP knock-in; flow cytometry; in situ hybridization

Results 1-7 (7)