Preparedness and competency of New Zealand graduates for general dental practice - perceptions from the workforce.

BACKGROUND: Dental graduates need to demonstrate clinical competency. This mixed-methods study explored the perceptions of clinicians who employ or work with new graduates from the University of Otago, New Zealand, and identified themes reflecting graduates' preparedness for independent practice. METHODS: An online survey using a semantic differential scale and open-ended questions collected opinions and experiences from the workforce. Quantitative data were analysed using SPSS software, and qualitative data were analysed thematically. RESULTS: A representative sample of the workforce was obtained with a response rate of 35% (N = 83). Most clinicians engage new graduates to support the profession and/or rural communities. They perceived that graduates were well prepared in most areas, could translate theory to clinical practice and demonstrate professionalism. Graduates were reportedly stronger in basic dentistry, communication, ethics, and record keeping however were less strong in complex treatment planning, molar endodontics, fixed prosthodontics and exodontia. Clinical exposure during dental training was perceived as more limited, and mentoring and guidance in the transition to practice were deemed to be important. CONCLUSIONS: New Zealand dental graduates appear prepared for independent practice; however, maximising clinical opportunities during training, mentoring and early professional development in advanced areas of practice is essential to enhance competency and confidence.

Potential application of immunotherapy for modulation of pulp inflammation: opportunities for vital pulp treatment.

Caries results in the demineralization and destruction of enamel and dentine, and as the disease progresses, irreversible pulpitis can occur. Vital pulp therapy (VPT) is directed towards pulp preservation and the prevention of the progression of inflammation. The outcomes of VPT are not always predictable, and there is often a poor correlation between clinical signs and symptoms, and the events occurring at a molecular level. The inflamed pulp expresses increased levels of cytokines, including tumour necrosis factor (TNF)-α, interleukin (IL)-1α, IL-1ß, IL-4, IL-6, IL-8, IL-17 and IL-23, which recruit and drive a complex cellular immune response. Chronic inflammation and sustained cytokine release can result in irreversible pulp damage and a decreased capacity for tissue healing. Other chronic inflammatory diseases, such as psoriasis, inflammatory bowel diseases and rheumatoid arthritis, are also characterized by an dysregulated immune response composed of relatively high cytokine levels and increased numbers of immune cells along with microbial and hard-soft tissue destructive pathologies. Whilst anti-cytokine therapies have been successfully applied in the treatment of these diseases, this approach is yet to be attempted in cases of pulp inflammation. This review therefore focuses on the similarities in the aetiology between chronic inflammatory diseases and pulpitis, and explores how anti-cytokine therapies could be applied to manage an inflamed pulp and facilitate healing. Further proof-of-concept studies and clinical trials are justified to determine the effectiveness of these treatments to enable more predictable outcomes in VPT.

Upregulation of angiogenesis in oral lichen planus.

OBJECTIVES: As angiogenesis is fundamental to the pathogenesis of many chronic inflammatory disorders, this study investigated the expression of various vascular markers in oral lichen planus and non-specific oral mucosal inflammatory tissues. METHODS: Archival specimens of oral lichen planus (n = 15) and inflamed tissues (n = 13) were stained using immunohistochemistry with antibodies to CD34, vascular endothelial growth factor, vascular endothelial growth factor receptor and vasohibin. Nine representative sites at the epithelial-connective tissue junction and through the fibrous connective tissue were selected, and automated analysis techniques were used to determine the extent of positivity expressed as the percentage of positive cells. Significance was denoted when P < .05. RESULTS: The expression of pro-angiogenic factors was higher in lichen planus samples compared with inflamed controls. A higher level of CD34 was observed in the deeper parts of the connective tissue of Oral lichen planus (OLP) (P = .04), whereas VEGF and VEGFR2 expressions were higher all through the tissues (respectively, P < .02 and P < .01). The expression of the anti-angiogenic VASH1 was higher in inflamed tissue compared with lichen planus in all sites evaluated (P < .01). CONCLUSIONS: The findings indicate that angiogenic factors are differentially expressed in oral lichen planus compared with inflamed controls, with increased expression of pro-angiogenic factors and decreased anti-angiogenic expression.

VEGF and VEGFR2 in dentigerous cysts associated with impacted third molars.

The aims of this study were to determine the presence and distribution of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR2) in dentigerous cysts compared with normal dental follicles as a control tissue and to evaluate endothelial cells and proliferating cells as indicators of angiogenic activity in these tissues.Twenty specimens histologically diagnosed as dentigerous cysts and 20 dental follicle specimens were included. Immunohistochemistry (IHC) using anti-VEGF and anti-VEGFR2 antibodies stained for the growth factor and its receptor, while anti-CD34 and anti-CD146 antibodies were used to identify endothelial cells. Anti-proliferating cell nuclear antigen (PCNA) antibody detected proliferating cells within the specimens. Slides were examined microscopically and results evaluated using kappa statistics, negative binomial regression and ordinal logistic regression.The mean age for patients with dentigerous cysts was 23 years and they were more common in males. Proteins for VEGF, VEGFR2, PCNA, CD34, and CD146 were expressed in all dentigerous cysts and dental follicles. VEGF and VEGFR2 were expressed on several cell types within the tissues, however there was a significantly greater percentage of positive staining in dentigerous cysts compared with dental follicles (odds ratio = 31.24, p < 0.001). CD34(+), CD146(+), and PCNA(+) cells were observed in both dentigerous cysts and dental follicles but for all markers there were significantly more positive cells in dentigerous cysts (p < 0.001); this was especially evident in cases associated with inflammation. PCNA was seen in most endothelial cells lining small thin walled blood vessels suggesting endothelial proliferation. There was a high level of intra- and inter-examiner agreement (kappa 0.77 and 0.75, respectively).VEGF and VEGFR2 and angiogenic activity are present in dental follicles and dentigerous cysts and may contribute to local bone resorption for tooth eruption or the development and progression of dentigerous cysts.

Regulation of immune cells in oral lichen planus.

Oral lichen planus (OLP) is an immunological disease and while it is understood that the T cell subsets, FoxP3(+) Tregs and IL17(+) Th17 cells are involved in immune regulation, little is known about their presence in OLP. The aims of this study were to compare the number of cells expressing FoxP3 or IL-17 in OLP with non-specifically inflamed oral mucosa and to determine which cell types expressed FoxP3 and/or IL-17 and their distribution. Immunohistochemistry was used to investigate the presence of FoxP3(+) or IL-17(+) cells in 12 control cases and 17 cases of OLP. These results were analysed quantitatively and qualitatively. Double-labelling immunofluorescence (IF) was used to determine the type of cell expressing FoxP3/IL-17 and these results were analysed qualitatively. OLP displayed significantly more FoxP3(+) cells (mean 79.3 vs. 20.6 cells/defined area, p < 0.0001) and fewer IL-17(+) cells (mean 1.05 vs. 3.30 cells/defined area, p = 0.0003) than non-specific inflammatory cases. The majority of FoxP3(+) cells were in the sub-epithelial infiltrate, while IL-17(+) cells were deeper in the stromal tissues. IF showed that FoxP3(+) cells co-localised with T cells, while the IL-17(+) cells did not. These results show that the balance between Tregs and IL-17(+) cells is altered in OLP, thus supporting the proposition that disturbance in local immune regulation is important in the pathogenesis of OLP. The observation that the IL-17(+) cells were mast cells has not previously been reported in OLP and again raises questions about the role of mast cells in this condition.

Expression of Toll-like receptors 2 and 4 and the OPG-RANKL-RANK system in inflammatory external root resorption and external cervical resorption.

AIM: To investigate and compare the expression of the pathogen recognition receptors Toll-like receptor (TLR) 2 and TLR4, and the hard tissue resorption triad osteoprotegerin (OPG)-receptor activator of nuclear factor kappa-B ligand (RANKL)-receptor activator of nuclear factor kappa-B (RANK) in external inflammatory root resorption of endodontic origin (ER) and external cervical root resorption (ECR) by immunohistochemistry. METHODOLOGY: Formalin-fixed, paraffin-embedded archival specimens collected from teeth that were diagnosed clinically, radiographically and histopathologically with either ER (n = 9) or ECR (n = 9) were processed for immunohistochemistry to investigate and compare levels of TLR2, TLR4, OPG, RANKL, RANK, CD3, CD19 and CD83 expression. The histological features were evaluated via haematoxylin and eosin stain. Taylor's modification of the Brown and Brenn Gram stain was used for examining the presence and distribution of bacteria. All stained slides were digitally photographed and qualitatively analysed, and F test and unpaired Student's t-test were used for statistical analysis. RESULTS: Both ER and ECR showed similar immuno-histopathology characteristics of a fibrovascular connective tissue with varying degrees of inflammatory infiltrate consisting of T and B lymphocytes, dendritic cells, polymorphonuclear lymphocytes and plasma cells. Colonies of bacteria were identified in the majority of lesions, and this correlated with the cellular expression of TLR2 and TLR4 in all lesions. Similarly, all lesions showed a significantly higher (P < 0.05) level of cells expressing RANKL than OPG, indicating hard tissue resorption processes where active in the lesions. CONCLUSION: The immunohistopathology patterns of ECR samples were consistent with the bacteria-driven ER specimens, suggesting bacteria-induced inflammation may be involved in ECR.

Influence of clinical experience on the radiographic determination of endodontic working length.

AIM: To determine the influence of clinical experience on the accuracy and consistency of estimation of radiographic working length (WL) for the root canal treatment of single-rooted teeth. METHODOLOGY: Forty conventional WL periapical radiographs that included variations in file length were selected. They were digitally scanned and arranged in PowerPoint presentations on CDs. These were distributed to three assessor groups; fourth-year undergraduates at two stages of training (Groups 1 and 2) and endodontic postgraduates (Group 3). Participants were asked to determine the adjustment needed in millimetres to position the file tip at the correct WL for each image. A gold standard file position was provided by three experienced endodontists. For inter-group comparison of scores, the Kruskal-Wallis, ANOVA and post hoc Bonferroni tests were used. Evaluation of intra-examiner consistency was with the Kappa test. To evaluate intra-group consistency, the Wilcoxon signed rank test was used to compare the frequency of weighted correct scorings. RESULTS: File adjustments of Group 3 were significantly more accurate than those of Group 1 (P = 0.006). The scores of Group 3 were also better than those of Group 2, although the difference was not significant. When the scores of the undergraduate groups were compared, the difference was not statistically significant. The consistency of the groups was not affected by a 2-week pause between assessments, and no definite pattern could be detected across any of the groups with the Kappa test. CONCLUSION: Clinical experience after graduation influenced the accuracy of estimating the adjustments needed for correct radiographic WL of single-rooted teeth. The most experienced group was significantly more accurate than the other groups.

Dental stem cells and their potential role in apexogenesis and apexification.

Injury to an immature permanent tooth may result in cessation of dentine deposition and root maturation leaving an open root apex and thin dentinal walls that are prone to fracture. Endodontic treatment is often complicated and protracted with an uncertain prognosis frequently resulting in premature tooth loss. Postnatal stem cells, which are capable of self-renewal, proliferation and differentiation into multiple specialized cell lineages have been isolated and identified within the dental pulp, apical papilla and periodontal ligament. The ability of these cells to produce pulp-dentine and cementum-periodontal ligament complexes in vivo suggest potential applications involving stem cells, growth factors and scaffolds for apexification or apexogenesis. Similar protein expression amongst dental stem cells possibly implicates a common origin; however, the dominant cells to repopulate an open apex will be directed by local environmental cues. A greater understanding of the structure and function of cells within their environment is necessary to regulate and facilitate cellular differentiation along a certain developmental path with subsequent tissue regeneration. This review focuses on development of the apical tissues, dental stem cells and their possible involvement clinically in closing the open root apex. MEDLINE and EMBASE computer databases were searched up to January 2009. Abstracts of all potentially relevant articles were scanned and their contents identified before retrieval of full articles. A manual search of article reference lists as well as a forward search on selected authors of these articles was undertaken. It appears that dental stem cells have the potential for continued cell division and regeneration to replace dental tissues lost through trauma or disease. Clinical applications using these cells for apexogenesis and apexification will be dependent on a greater understanding of the environment at the immature root end and what stimulates dental stem cells to begin dividing and then express a certain phenotype.