Impact of Case Difficulty on Endodontic Mishaps in an Undergraduate Student Clinic.

INTRODUCTION: The aim of this study was to identify the effect of case difficulty on the number of endodontic mishaps and the number of treatment visits using 2 different instrumentation methods, hand files, and reciprocating engine-driven WaveOne files (Dentsply Maillefer, Ballaigues, Switzerland) in an undergraduate student clinic. METHODS: Endodontic treatment performed by fourth-year dental students using 2 different instrumentation methods was evaluated: hand files and reciprocating engine-driven WaveOne files. All cases were categorized according to the American Association of Endodontists case difficulty assessment form. Endodontic mishaps related to instrumentation and treatment visits needed to complete the treatment were recorded. RESULTS: Of the 257 teeth included in the study, 141 were instrumented with hand files and 116 with WaveOne files. Eighty-two teeth (31.9%) were registered with at least 1 endodontic mishap. The most frequent endodontic mishap was overinstrumentation (17.5%). This was followed by loss of working length (8.56%), obturation more than 2 mm from the radiographic apex (8.56%), overfill with gutta-percha (6.61%), canal transportation (4.28%), instrument separation (2.33%), and lateral or strip perforation (1.56%). Several endodontic mishaps were significantly correlated. Cases in the high difficulty category had significantly more endodontic mishaps (P < .001) and required more treatment visits (P < .01). There were no significant differences in endodontic mishaps or the number of treatment visits between the hand and engine-driven groups. Several endodontic mishaps were associated with significantly more treatment visits (P < .05). CONCLUSIONS: Case difficulty rather than the instrumentation method was the main determinant of endodontic mishaps in the undergraduate clinic. The American Association of Endodontists case difficulty assessment form is an important and valuable tool in undergraduate dental education to predict potential endodontic mishaps and the number of treatment visits.

High interstitial fluid pressure in rat tongue cancer is related to increased lymph vessel area, tumor size, invasiveness and decreased body weight.

BACKGROUND: Interstitial fluid pressure (IFP) in most tumors is high, and this high pressure has been correlated with poor prognosis. Measurements of IFP in normal tongue and in tongue cancer are lacking. Recent research suggests the existence of a relationship between increased peritumoral lymph vessels (PTLV) and survival, and a correlation of increased lymphatic vessel density with an unfavorable prognosis has been reported. MATERIALS AND METHODS: In the present study, tongue squamous cell carcinoma (SCC) was induced by adding the carcinogen 4-nitroquinoline oxide in drinking water for 19 weeks. The IFP was measured by micropuncture and immunohistochemistry was used to visualize lymph vessels. RESULTS: In normal tongue, IFP averaged 3.1 +/- 0.3 mmHg. The IFP, both in the tumor (29.1 +/- 2.9 mmHg) and 0.5 cm anterior to it (15.4 +/- 2.1 mmHg) was consistently increased (P < 0.005) with values ranging from 10 to 40 mmHg. The highest IFP values were measured in rats with large tumors (P < 0.05) and low body weight (P < 0.001), suggesting that IFP increases with cancer progression. Lymphatic vessel area (%), as determined with the lymphatic specific marker LYVE-1 antibody, was significantly increased in the peritumoral area when compared to intratumoral and control mucosa (P < 0.05). There was a significant positive correlation between IFP, PTLV area, tumor size and invasiveness. CONCLUSIONS: Our data show that IFP is increased in tongue cancer. Corresponding changes in PTLV area, invasiveness, tumor area and IFP suggest that the increased pressure is caused by defective lymph drainage and solid stress generated by tumor cells growing in a low compliant environment.

IL-1 alpha and TNF-alpha expression in rat periapical lesions and dental pulp after unilateral sympathectomy.

OBJECTIVES: Apical periodontitis is an inflammatory disease characterized by bone resorption, and sympathetic nerves are known to modulate bone resorption and bone remodeling. Higher numbers of osteoclasts and larger periapical lesions have been observed after sympathectomy in rats, but the mechanisms underlying the inhibitory effect of sympathetic nerves on osteoclasts are unknown. This study aimed to test the hypothesis that sympathetic nerves inhibit the production of the bone-resorbing pro-inflammatory cytokines IL-1 alpha and TNF-alpha in rat periapical lesions. METHODS: Rats were unilaterally sympathectomized and apical lesions were induced by exposing the dental pulp of molar teeth to the oral microflora. We quantified the cytokines IL-1 alpha and TNF-alpha by enzyme-linked immunosorbent assay, and immunohistochemical analysis was done for qualitative localization. Pulp from intact incisor teeth was tested as a control. RESULTS: We showed that IL-1 alpha was increased, but not TNF-alpha, in the periapical lesions on the sympathectomized side. Both IL-1 alpha and TNF-alpha were expressed in unexposed pulp. TNF-alpha was significantly decreased in the denervated incisor pulp, whereas the level of IL-1 alpha remained unchanged. CONCLUSIONS: This study suggests that sympathetic nerves have an inhibitory effect on IL-1 alpha in periapical lesions and a stimulatory effect on TNF-alpha in the intact rat pulp.

Sympathectomy causes increased root resorption after orthodontic tooth movement in rats: immunohistochemical study.

Accumulating evidence suggests that the sympathetic nervous system modulates inflammatory responses and bone remodeling. We have studied the effects of sympathectomy and orthodontic tooth movement (OTM) on root resorption, immunocompetent cell recruitment, neuropeptide, neurokinin-1 receptor (NK1-R), and interleukin 6 (IL-6) expression. Experimental rats (n=8) had the right superior cervical ganglion surgically removed, whereas control rats (n=6) underwent sham surgery. Three days later, all rats had the right maxillary first molar moved mesially by an orthodontic appliance. The rats were perfused 13 days later, and the right maxillae were processed for immunohistochemistry by using primary antibodies directed against ED1 antigen, CD43, substance P (SP), NK1-R, neuropeptide Y (NPY), and IL-6. Following OTM, sympathectomized (SCGx) rats had significantly more root resorption (P<0.01) and SP-immunoreactive (IR) fibers (P=0.01) in the compressed periodontal ligament (PDL) compared with control rats. There was a significant decrease in recruitment of CD43+ cells in the pulp after OTM in SCGx rats compared with control rats (P=0.02). An upregulation of NK1-R immunoreactivity was observed surrounding the hyalinized tissue, and an increase in the number of NK1-R IR cells and density of SP-IR fibers was present in first molar pulp of all rats. NPY-IR fibers were absent in the compressed PDL of SCGx and control rats. Thus, OTM induces remodeling not only around the periodontal tissues, but also in the dental pulp. The sympathetic nerves have an inhibitory effect on hard tissue resorption and a stimulatory effect on CD43+ cell recruitment after OTM.