Internal morphology of 101 mandibular canines of a Swiss-German population by means of micro-CT: An ex vivo study.

The aim of this study was to investigate the root canal system morphology by means of a root canal configuration (RCC) classification described with a four-digit system, the physiological foramen geometry and accessory canal frequency and morphology, of 101 mandibular canines (MaCa) of a Swiss-German population by means of micro-computed tomography. Micro-CT examination of the MaCa was performed and the obtained images analyzed with a 3D imaging software. In single-rooted MaCas, the most frequently observed RCCs were 1-1-1/1 (74.5%) and 1-1-1/2 (14.3%). Seven other RCCs were less frequently observed with a frequency from 4.1 to 1.0%. One physiological foramen was observed in 80.6% of the MaCas, two in 16.3%, three in 1.0% and four in 2.0%. Accessory and connecting canals were apparent only in the middle and apical root thirds. Two-rooted MaCas occurred less frequently (n = 3). When one physiological foramen was present, the mean size of the narrow and wide diameters were 0.28 mm (± 0.07) and 0.40 mm (± 0.11), while the distance between physiological and anatomical foramen was 0.45 mm (± 0.17). MaCas are predominantly single-rooted teeth with a 1-1-1/1 or 1-1-1/2 RCC. Most MaCas had one physiological foramen with an oval shape.

Anatomy of the female pelvic nerves: a macroscopic study of the hypogastric plexus and their relations and variations.

The autonomic nerves of the lesser pelvis are particularly prone to iatrogenic lesions due to their exposed position during manifold surgical interventions. Nevertheless, the cause of rectal and urinary incontinence or sexual dysfunctions, for example after rectal cancer resection or hysterectomy, remains largely understudied, particularly with regard to the female pelvic autonomic plexuses. This study focused on the macroscopic description of the superior hypogastric plexus, hypogastric nerves, inferior hypogastric plexus, the parasympathetic pelvic splanchnic nerves and the sympathetic fibres. Their arrangement is described in relation to commonly used surgical landmarks such as the sacral promontory, ureters, uterosacral ligaments, uterine and rectal blood vessels. Thirty-one embalmed female pelvises from 20 formalin-fixed and 11 Thiel-fixed cadavers were prepared. In all cases explored, the superior hypogastric plexus was situated anterior to the bifurcation of the abdominal aorta. In 60% of specimens, it reached the sacral promontory, whereas in 40% of specimens, it continued across the pelvic brim until S1. In about 25% of the subjects, we detected an accessory hypogastric nerve, which has not been systematically described so far. It originated medially from the inferior margin of the superior hypogastric plexus and continued medially into the presacral space. The existence of an accessory hypogastric nerve was confirmed during laparoscopy and by histological examination. The inferior hypogastric plexuses formed fan-shaped plexiform structures at the end of both hypogastric nerves, exactly at the junction of the ureter and the posterior wall of the uterine artery at the uterosacral ligament. In addition to the pelvic splanchnic nerves from S2-S4, which joined the inferior hypogastric plexus, 18% of the specimens in the present study revealed an additional pelvic splanchnic nerve originating from the S1 sacral root. In general, form, breadth and alignment of the autonomic nerves displayed large individual variations, which could also have a clinical impact on the postoperative function of the pelvic organs. The study serves as a basis for future investigations on the autonomic innervation of the female pelvic organs.

3-dimensional Analysis and Literature Review of the Root Canal Morphology and Physiological Foramen Geometry of 125 Mandibular Incisors by Means of Micro-Computed Tomography in a German Population.

INTRODUCTION: The aim of this study was to examine the root canal system morphology of mandibular incisors by means of micro-computed tomographic imaging. METHODS: The root canal configuration, physiological foramina, frequency of accessory and connecting canals, and the size and shape of the physiological foramina of 125 mandibular incisors were investigated by means of micro-CT and 3-dimensional imaging software. Root canal configuration of the coronal, middle, and apical thirds and the physiological foramina number are described by a 4-digit system code. RESULTS: The most frequent root canal configurations were 1-1-1/1 (56%), 1-2-1/1 (17.6%), and 1-1-1/2 (10.4%); 9 additional different root canal configurations were observed. Single-rooted incisors showed in 80% 1, in 16% 2, and in 4% 3 physiological foramina, respectively. Accessory canals were found in only 13.6% of the investigated teeth. Connecting canals were observed in 36% of the sample, most often in root canal configurations 1-2-1/1 (12.8%) and 2-2-1/1 (7.2%). The morphologic dimensions of a total of 146 physiological foramina were measured. Their mean wide and narrow diameters were 0.24 mm (standard deviation = 0.1 mm) and 0.23 mm (standard deviation = 0.08 mm) when only 1 physiological foramen was present. The physiological foramen shapes observed were oval (56%), round (28.8%), and irregular (15.2%). CONCLUSIONS: The study provides detailed information about the root canal morphology of anterior teeth in a German population. Within the limitations of the study, the authors recommend according to results obtained in this investigation a final physiological foramen preparation size of ISO 30-35; yet, such a decision should be carefully considered on an individual basis.

Augmented marker tracking for peri-acetabular osteotomy surgery.

OBJECTIVE: To develop a hybrid augmented marker-based navigation system for acetabular reorientation during peri-acetabular osteotomy (PAO). METHODS: The system consists of a tracking unit attached to the patient's pelvis, augmented marker attached to the acetabular fragment and a host computer to do all the computations and visualization. The augmented marker is comprised of an external planar Aruco marker facing toward the tracking unit and an internal inertial measurement unit (IMU) to measure its orientation. The orientation output from the IMU is sent to the host computer. The tracking unit streams a live video of the augmented marker to the host computer, where the planar marker is detected and its pose is estimated. A Kalman filter-based sensor fusion combines the output from marker tracking and the IMU. We validated the proposed system using a plastic bone study and a cadaver study. Every time, we compared the inclination and anteversion values measured by the proposed system to those from a previously developed optical tracking-based navigation system. RESULTS: Mean absolute differences for inclination and anteversion were 1.34 ([Formula: see text]) and 1.21 ([Formula: see text])[Formula: see text], respectively, for the cadaver study. Mean absolute differences were 1.63 ([Formula: see text]) and 1.55 ([Formula: see text])[Formula: see text] for inclination and anteversion for the plastic bone study. In both validation studies, very strong correlations were observed. CONCLUSION: We successfully demonstrated the feasibility of our system to measure the acetabular orientation during PAO.

Augmented marker tracking for peri-acetabular osteotomy surgery.

We developed and validated a small, easy to use and cost-effective augmented marker-based hybrid navigation system for peri-acetabular osteotomy (PAO) surgery. The hybrid system consists of a tracking unit directly placed on the patient's pelvis, an augmented marker with an integrated inertial measurement unit ('MU) attached to the patient's acetabular fragment and the host computer. The tracking unit sends a live video stream of the marker to the host computer where the marker's pose is estimated. The augmented marker with the 'MU sends its pose estimate to the host computer where we apply sensor fusion to compute the final marker pose estimate. The host computer then tracks the orientation of the acetabular fragment during peri-acetabular osteotomy surgery. Anatomy registration is done using a previously developed registration device. A Kalman filter-based sensor fusion was added to complete the system. A plastic bone study was performed for validation between an optical tracking-based navigation system and our proposed system. Mean absolute difference for inclination and anteversion was 1.63 degrees and 1.55 degrees, respectively. The results show that our system is able to accurately measure the orientation of the acetabular fragment.