Evaluation of the Shaping Ability of Three Thermally Treated Nickel–Titanium Endodontic Instruments on Standardized 3D-printed Dental Replicas Using Cone-Beam Computed Tomography

Background and Objectives: The aim of the present study is to compare the efficacy of three root canal preparation systems in the shaping of 3D-printed root canal replicas of single rooted teeth. Materials and Methods: Sixty 3D-printed root canal replicas were produced and divided into three groups, each consisting of twenty samples. Each group was shaped with a different instrument: Reciproc Blue R25/08 (VDW GmbH, Munich, Gemany), WaveOne Gold Primary 25/07 (Dentsply Sirona, Ballaigues, Switzerland), and ProTaper Gold F2 25/08 (Denstply Sirona). To ensure the reproducibility of pre- and post-operative CBCT images of the root canals, the endodontic printed replicas were placed in a mould of silicon impression material. A cone-beam computed tomography (CBCT) software was used to compare pre- and post-instrumentation images collected at three levels of the root canal length: 3, 6, and 9 mm from the apical foramen. The amount of transportation, centring ability, and curvature angle after shaping were evaluated for each system. The results were statistically analysed and compared using one-way analysis of variance (ANOVA). Results: Regarding the transportation of the root canal after shaping, significant differences between groups at 3 mm (p = 0.010721) and 6 mm (p = 0.000046) were recorded in the mesio-distal direction, while in the bucco-lingual significant differences were only observed at 6 mm (p = 0.000554). Reciproc Blue removed more dentin from the mesial and buccal wall of the root canal. When evaluating the centring ability of the three systems, significant differences were observed between the groups at the level of 9 mm (p = 0.037258) in the mesio-distal direction, and at the level of 6 mm (p = 0.038197) in the bucco-lingual direction. Significant differences of the canal curvature angle after shaping were also observed between groups (p = 0.000001). Reciproc Blue straightened the curvature the most, while ProTaper Gold the least. Conclusions: All systems produced minor root canal transportation. No instrument was able to achieve a perfect centring preparation of the root canal. All systems produced a small degree of root canal straightening.

THE POTENTIAL OF MICROCOMPUTED TOMOGRAPHY IN STUDYING THE VARIANT MORPHOLOGY OF THE DENTAL CANAL-ROOT SYSTEM

— High-resolution microfocus computed tomography performed on a Skyscan 1176 (Bruker) device was used to study morphological features of the canal-root systems of the upper jaw first molars in residents of the European part of Russia. An analysis of coronal, axial and sagittal sections of 134 upper jaw first permanent molars removed for medical reasons revealed variations in the canal-root system structure. In 85.8% of the cases, the first upper molars had three separate roots: two vestibular and one palatal; in 14.2% of the cases the roots make up different fusions. The palatal root bent in the buccal direction in 52.9% of the cases, while the mesiobuccal root bent in the distal direction in 87.9% of the cases. The greatest variety of curvatures was observed in the distal-buccal root: towards the mesial side — in 28.3% of the cases, another 21.6% of cases being curved towards the distal side. The palatal root in 90.3% of the cases had one canal; 9.7% of the cases featured two canals, while the distal-buccal root in 73.9% of the cases had one canal, and two canals — in 26.1% of the cases. In 89.6% of the cases, the mesiobuccal root had two canals; in 10.4% of the cases — one canal. The mesiobuccal root of the first upper molars was of an oval shape, elongated in the vestibular-oral direction, the most common structures being those of Type IV (43,3%), II (25.4%), III (8.2%) and VI (7.4%) by F. J. Vertucci. The occurrence rate of extra types of root canal structure was 7.4%.

Morphometric evaluation of the slot of aesthetic orthodontic brackets.

Introduction: : Dental malocclusion is a public health problem and orthodontics is the specialty in charge of diagnosing and treating it, aesthetic brackets are an alternative, the costs are varied, which makes its precision doubtful. Objective: Evaluate the measurement and geometry of the slot of three brands of aesthetic brackets and verify their precision. Material and Methods: Twenty-four aesthetic Roth prescription 0.022” slot polycrystalline ceramic brackets were evaluated in three brands: American Orthodontics (United States), Morelli (Brazil) and Class One (China). Eight samples were measured per group in a specialized laboratory certified in measurement and calibration, the measurements of internal and external height were verified, per mesial and distal; and the parallelism of the slot of each bracket. The results were processed with SPSS 22 and tests of variance (ANOVA), Tukey and Student's t were used. Results: The measurements of the brackets' grooves do not correspond to the measurements announced by the manufacturers, these are greater, however, American Orthodontics is within the tolerance range (p<0.01); the slots in the mesio-distal direction and the lingual vestibule are not parallel in Morelli and Class One. Conclusion: The results of this study indicate that the slots of the supports are oversized, their geometry is not precise and varies greatly between brands and prices. The three-dimensional control of the tooth could be compromised.

Computer-Aided Assessment of Displacement and Reduction of Distal Radius Fractures

This study aims to investigate displacements and reductions of distal radius fractures using measurement indices based on the computer-aided three-dimensional (3D) radius shape model. Fifty-two distal radius fracture patients who underwent osteosynthesis were evaluated with pre- and post-operative distal radius 3D images. In the 3D images, three reference points, i.e., the radial styloid process (1), sigmoid notch volar, and dorsal edge (2) (3) were marked. The three-dimensional coordinates of each reference point and the barycentric coordinates of the plane connecting the three reference points were evaluated. The distance and direction moved, due to the reductions for each reference point, were (1) 12.1 ± 8.1 mm in the ulnar-palmar-distal direction, (2) 7.5 ± 4.1 mm in the ulnar-palmar-proximal direction, and (3) 8.2 ± 4.7 mm in the ulnar-palmar-distal direction relative to the preoperative position. The barycentric coordinate moved 8.4 ± 5.3 mm in the ulnar-palmar-distal direction compared to the preoperative position. This analyzing method will be helpful to understand the three-dimensional direction and the extent of displacements in distal radius fractures.

RONTGEN-MORPHOMETRIC DATA TO THE CORRELATION OF THE PHALANXES LENGTH WITH A LENGTH OF HUMAN HANDS FINGERS

Data on the anatomical variability of the phalanges and fingers of the hand are needed to expand biometric databases in robotics, prosthetics, and forensic medicine. The aim of the study was to study the X-ray morphometric variability of the length of individual phalanges of the fingers of the hand, their relationship with the length of the fingers. By the method of morphometry, the lengths of individual phalanges and fingers of the hands were determined on 100 certified radiographs of the hands of persons of the second mature age (50 men and 50 women), and a correlation was established between the length of the phalanges and fingers. To identify the statistical relationship between quantitative characteristics, the parametric Pearson correlation coefficient was used. The relationship between quantitative indicators was assessed using multiple regression analysis. Classification and grouping were carried out using cluster analysis by the complete connection method, the Euclidean distance served as a measure of the relationship. The variability in the length of the phalanges and fingers increases towards the ulnar edge. The X-ray morphometric length of individual phalanges and fingers is characterized, regardless of gender, by regular formulas of variability: the length of the proximal phalanges is III>IV>II>V>I, the length of the middle phalanges is III>IV>II>V, the length of the distal phalanges is I>IV> III>II>V, finger length - III>IV>II>V>I. The degree of dependence of the length of the fingers on the length of the phalanges in both men and women decreases in the distal direction in the longitudinal axis and the ulnar edge in the transverse axis of the hand. As a result of cluster analysis, the organization of the objects of study was established depending on the degree of correlations of their length: groups of proximal phalanges of II-IV and I, V fingers, groups of middle phalanges of III-IV and II-V fingers, distal phalanges and fingers are organized somewhat more complexly - groups III -IV, II, V fingers and group I fingers. The data obtained can be used in the development of innovative anatomically grounded anthropomorphic robotic manipulators, in anthropological reconstructions, and in identification in forensic practice.

The Subgenual Organ Complex in Stick Insects: Functional Morphology and Mechanical Coupling of a Complex Mechanosensory Organ

Leg chordotonal organs in insects show different adaptations to detect body movements, substrate vibrations, or airborne sound. In the proximal tibia of stick insects occur two chordotonal organs: the subgenual organ, a highly sensitive vibration receptor organ, and the distal organ, of which the function is yet unknown. The distal organ consists of a linear set of scolopidial sensilla extending in the tibia in distal direction toward the tarsus. Similar organs occur in the elaborate hearing organs in crickets and bushcrickets, where the auditory sensilla are closely associated with thin tympanal membranes and auditory trachea in the leg. Here, we document the position and attachment points for the distal organ in three species of stick insects without auditory adaptations (Ramulus artemis, Sipyloidea sipylus, and Carausius morosus). The distal organ is located in the dorsal hemolymph channel and attaches at the proximal end to the dorsal and posterior leg cuticle by tissue strands. The central part of the distal organ is placed closer to the dorsal cuticle and is suspended by fine tissue strands. The anterior part is clearly separated from the tracheae, while the distal part of the organ is placed over the anterior trachea. The distal organ is not connected to a tendon or muscle, which would indicate a proprioceptive function. The sensilla in the distal organ have dendrites oriented in distal direction in the leg. This morphology does not reveal obvious auditory adaptations as in tympanal organs, while the position in the hemolymph channel and the direction of dendrites indicate responses to forces in longitudinal direction of the leg, likely vibrational stimuli transmitted in the leg’s hemolymph. The evolutionary convergence of complex chordotonal organs with linear sensilla sets between tympanal hearing organs and atympanate organs in stick insects is emphasized by the different functional morphologies and sensory specializations.

Relationship between distension-contraction waveforms during esophageal peristalsis: effect of bolus volume, viscosity, and posture

We studied esophageal distension (surrogate of inhibition) ahead of contraction during peristalsis from intraluminal esophageal impedance measurements. Esophageal distension, similarly to contraction, travels the esophagus in a sequential manner, and the amplitude of esophageal distension increases from proximal to distal direction in the esophagus. Bolus volume, viscosity, and posture have significant effects on the amplitude of distension and its temporal relationship with contraction.

ASSESSMENT OF ANATOMICAL CONDITIONS FOR THE INSTALLATION OF MINISCREWS «BIORAY A1» IN THE AREA OF THE MANDIBULAR BUCCAL SHELF

Currently, miniscrews installed parallel to the roots are widely used in the practice of orthodontic treatment. When planning the placement of miniimplants, it is necessary to evaluate the anatomical factors that affect the stability of the miniscrew in the bone. For the analysis, we selected the zone of the external oblique line, where the thickness of bone tissue in the area of the first and second molars was estimated in the vertical and horizontal planes. As a result of the study, it was found that the area of the distal surface of the distal root of the second molar had the greatest thickness of bone tissue. An increase in the vestibular-oral thickness was also observed in the distal direction.

Segmental Histological Normalisation Occurs in Ulcerative Colitis but Does Not Improve Clinical Outcomes

Background and Aims Complete histological normalisation and reduction of inflammation severity in patients with ulcerative colitis are associated with improved clinical outcomes, but the clinical significance of normalisation of only segments of previously affected bowel is not known. We examined the prevalence, pattern, predictors, and clinical outcomes associated with segmental histological normalisation in in patients with ulcerative colitis. Methods Medical records of patients with confirmed ulcerative colitis and more than one colonoscopy were sought. Segmental histological normalisation was defined as histological normalisation of a bowel segment [rectum, left-sided or right-sided colon] that had previous evidence of chronic histological injury. We assessed the variables influencing these findings and whether segmental normalisation was associated with improved clinical outcomes. Results Of 646 patients, 32% had segmental and 10% complete histological normalisaton when compared with their maximal disease extent. Most [88%] had segmental normalisation in a proximal-to-distal direction. Others had distal-to-proximal or patchy normalisation. On multivariate analysis, only current smoking [p = 0.040] and age of diagnosis ≤16 years [p = 0.028] predicted segmental histological normalisation. Of 310 who were in clinical remission at initial colonoscopy, 77 [25%] experienced clinical relapse after median 1.3 [range 0.06–7.52] years. Only complete histological normalisation of the bowel was associated with improved relapse-free survival (hazard ratio [HR] 0.23; 95% confidence interval [CI] 0.08–0.68; p = 0.008]. Conclusions Segmental histological normalisation occurs in 32% of patients with ulcerative colitis and is increased in those who smoke or were diagnosed at younger age. Unlike complete histological normalisation, segmental normalisation does not signal improved clinical outcomes.