Comparison of 2 Canal Preparation Techniques in the Induction of Microcracks: A Pilot Study with Cadaver Mandibles

Introduction

The purpose of this pilot study in a cadaver model was to compare 2 different shaping techniques regarding the induction of dentinal microcracks.

Methods

Three lower incisors from each of 6 adult human cadaver skulls were randomly distributed into 3 groups: the control group (CG, no instrumentation), the GT group (GT Profile hand files; Dentsply Tulsa Dental, Tulsa, OK), and the WO group (WaveOne; Dentsply Tulsa Dental). In the GT group, manual shaping in a crown-down sequence with GT Profile hand files was performed. In the WO group, Primary WaveOne files were used to the working length. Teeth were separated from the mandibles by careful removal of soft tissue and bone under magnification. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex using a low-speed saw. Color photographs at 2 magnifications (25× and 40×) were obtained. Three blinded examiners registered the presence of microcracks (yes/no), extension (incomplete/complete), direction (buccolingual/mesiodistal), and location. Data were analyzed with chi-square tests at P < .05.

Results

Microcracks were found in 50% (CG and GT) and 66% (WO) of teeth at 3 mm, 16.6% (CG) and 33.3% (GT and WO) at 6 mm, and 16.6% in all 3 groups at 9 mm from the apex. There were no significant differences in the incidence of microcracks between all groups at 3 (P = .8), 6 (P = .8), or 9 mm (P = 1). All microcracks were incomplete, started at the pulpal wall, and had a buccolingual direction.

Conclusions

Within the limitations of this pilot study, a relationship between the shaping techniques (GT hand and WaveOne) and the incidence of microcracks could not be shown compared with uninstrumented controls.     

Urbanicity,race, and psychological distress

Data from random samples of 645 rural White respondents, 398 rural Black respondents, and 700 urban residents of Nashville, Tennessee (375 White, 326 Black participants), are presented that address urbanicity and race differences in depressive symptoms, psychophysiologic symptoms, and general well-being. After demographic controls, significant urban-rural differences were found only on depressive symptoms, with greater distress in rural areas. Black participants had significantly higher depression scores than White respondents, though race differences were reversed on psychophysiologic symptoms and general well-being. Interaction effects were striking. Urban-rural differences were specific to Black participants—rural Black residents had higher depressive symptom scores than urban Black residents. These differences were reversed on psychophysiologic symptoms and well-being. Race differences were specific to the rural sample; rural Black respondents manifested more depressive symptoms than did rural White participants, though rural White residents had more psychophysiologic symptoms and lower well-being. These findings withstood further controls for migration/length of residence. Implications of these findings for stress models of urbanicity and race differences are considered.     

Meniscal impingement syndrome

The meniscal impingement syndrome consists of three elements: impaction on the anterior medial femoral condyle by the leading edge of the medial meniscus, articular cartilage damage of at least Outerbridge grade 3, and knee hyperextension of at least 5°. This report reviews this condition in a series of seven knees with an average follow-up of 39 months. The time from the onset of symptoms until surgery averaged 45 months. Treatment consisted of a thorough arthroscopic knee evaluation and debridement of the articular cartilage fragmentation and any impinging synovitis. Postoperative rehabilitation includes extension block bracing, hamstring strengthening, and closed-chain exercise. With this regimen, there was improvement in the Tegner scores and a reduction in postoperative knee hyperextension. Identification of this uncommon condition requires a complete evaluation of the medial femoral condyle in patients with knee hyperextension.     

Carpal tunnel syndrome associated with extra tunnel vascular compression of the median nerve motor branch

We report a case of carpal tunnel syndrome associated with median nerve motor branch compression by a large superficial palmar branch of the radial artery.