Canal Shape Research Articles

Using a one-dimensional finite-element approximation of Webster's horn equation to estimate individual ear canal acoustic transfer from input impedances

Knowledge of the sound pressure transfer to the eardrum is important. The transfer is highly influenced by the shape of the ear canal and its acoustic properties, such as the acoustic impedance at the eardrum. Invasive procedures to measure the sound pressure at the eardrum are usually elaborate or costly. We propose a numerical method to estimate the transfer impedance of the ear canal given only input impedance measurements at the ear canal entrance, by using one-dimensional first-order finite elements and Nelder-Mead optimization algorithm. Estimations on the area function of the ear canal and the acoustic impedance at the eardrum are achieved. Results are validated through numerical simulations on ten different ear canal geometries and three different acoustic impedances at the eardrum, using synthetically generated data from three-dimensional finite element simulations.

A chromosomal deletion leading to BACH2 haploinsufficiency, hypogammaglobulinemia and recurrent infections without intestinal inflammation or autoimmunity

Afzali et al. described 3 patients with heterozygous point mutations in the transcription factor BACH2, characterized by lymphocyte maturation defects, immunoglobulin deficiency and intestinal inflammation secondary to BACH2-related immunodeficiency and autoimmunity (BRIDA). Molecular testing suggested these mutations lead to disruption of protein stability. Mice with heterozygous Bach2 deficiency display similar lymphocyte defects, supporting that the disease-mechanism was BACH2 haploinsufficiency. We present a patient with recurrent infections and hypogammaglobulinemia with heterozygous chromosome 6 deletion encompassing the BACH2 gene, in absence of gastrointestinal or rheumatologic manifestations.A 3-year old boy with developmental delay, corpus callosum dysgenesis, dextrocardia, renal pyelectasis, abnormal ear canal shape and congenital hypotonia presented to immunology clinic for evaluation of recurrent infections. In his first 18 months he was isolated, but subsequently developed notable respiratory infections in daycare. Genetic testing identified a chromosome 6 deletion of 8.18Mb (6q14.3-q16); chr6:85227585-93409505, likely de novo, given no affected family members and mother’s chromosomal analysis revealed no translocation. Research WES showed no other variants of interest. 7 known disease genes lie within this region (Figure 1). MAP3K7 and TBX18 deletion were thought to explain the developmental and cardiac phenotypes.Table 1. (abstract: 96)Selected laboratory test results. Values below or above reference are indicated with blue and red respectively. Not shown: IL-2, IL-4, IL-5, IL-8, IL-12, IL-13, IL-17 were normal. Fecal blood testing at baseline was negative. T cell memory population percentages were normal. T cell proliferation studies were normal. Pre-SCIG = pre-subcutaneous IgG (SCIG) treatment. Post SCIG = post-SCIG treatment sample obtained after ~ 4 months of SCIG. n/a = sample not available.ParameterValue pre-SCIGValue post-SCIG UnitWBC19.6810.15 K cells/ulHgb12.211.9 K cells/ulPlatelet274279 K cells/ulANC13.114.05 K cells/ulALC4.724.98 K cells/ulIgG459871 mg/dLIgA4946 mg/dLIgM4039 mg/dLIgE7866 unit/mLC3n/a116 mg/dLC4n/a18 mg/dLC-reactive protein (CRP)0.4<0.06 mg/dLErythrocyte Secimentation Rate (ESR)101 mm/hrsIL2R27411154.1 pg/mLIFN-gamma<4.2<4.2 pg/mLIL-1020.13.6 pg/mLIL-68.4<2.0 pg/mLIL-1beta<6.5<6.5 pg/mLTNF-alpha2.3<1.7 pg/mLTotal T cells (CD3+)29543566 cells/ulCD4+ T cells (CD3+CD4+)19302229 cells/ulCD8+ T Cells (CD3+CD8+)9081167 cells/ulB cells (CD19+)10681051 cells/ulNK cells (CD3-/CD16+ or CD56+)751188 cells/ulNaïve CD4+ (CD45RA+CCR7+)83.774.1 %Naïve CD8+ (CD45RA+CCR7+)77.376 %Treg (CD4+ CD25hiCD127lo)5.68.8 %Naïve B cells (IgD+CD27-)88.4n/a %Unswitchedmem B cells (IgD+CD27+)4n/a %Switched mem B cells (IgD-CD27+)4.2n/a %Transitional B cells (CD24hiCD38hi)31.527.2 %Marginal Zone-like B cells (CD24hiCD38lo)614.5 %CD 19+CD21loCD38lo B cells2.81.6 %Plasmablasts (CD24loCD38hi)0.90.6 %Fecal calprotectin30n/a mcg/gFecal lactoferrinnegn/a mcg/mL [Display omitted] We assessed the impact of heterozygous BACH2 deletion on his immunophenotype. Detailed in Table 1, laboratory findings partially consistent with published BACH2 patients were hypogammaglobulinemia, decreased “Treg”% (CD25hiCD127lo, Foxp3 expression pending) and elevated transitional B cells. Contrary to patients previously described, he had no decreased memory B cells and had normal T cell proliferation. Prior patients had intestinal inflammation and one was ANCA+. Our patient’s cytokine panel showed mild elevations in sIL2R, IL-10 and IL-6, which resolved after SCIG initiation. Stool inflammatory markers were normal and evaluation by gastroenterology and rheumatology was reassuring. Of note, our patient is significantly younger than published patients, thus autoimmunity could develop with time. The frequency of patient’s infections improved since initiation of SCIG.In summary, we describe the first patient with immunodeficiency and clear BACH2 haploinsufficiency due to a chromosomal deletion, with recurrent infections and hypogammaglobulinemia in absence of intestinal inflammation or autoimmunity to date. He exhibits partially overlapping immunophenotype compared to described patients with BACH2 point mutations.

Influence of brushing motions on the shaping of oval canals by rotary and reciprocating instruments.

The effects of brushing on shaping with three different instruments were assessed in oval canals. Mandibular incisors were assigned to 6 groups (n = 12/group) according to the system, each one with or without brushing: Reciproc Blue, VDW.Rotate, and Race EVO. Micro-computed tomography was performed before and after preparation. Brushing strokes caused no increase in canal volume, surface area, and structure model index independently of the system (p > 0.05), except for RaCe EVO in the full canal surface area (p < 0.05). Brushing did not increase the prepared areas (p > 0.05), except for Reciproc in the apical canal (p < 0.05). Reciproc with no brushing exhibited less pericervical dentin than with brushing (p < 0.05), while RaCe EVO with brushing resulted in less remaining dentin (p < 0.05). The brushing motion had no effects on the overall shaping performance of the 3 instruments tested. An exception was the increase in prepared surface area in the apical canal segment when the Reciproc instrument was used with brushing strokes.

An Examination of the Impact of Blue Heat Treatment on the Forced Caused by the Vertical Motion of Endodontic Files

Objective: To assess the vertical forces produced during canal shaping by the Reciproc Blue (RB) and Reciproc (R) systems. Place and Duration: In the Operative Dentistry Department, Altamash Institute of Dental Medicine Karachi for one-year duration from January 2022 to December 2022. Methods: A total of 32 maxillary premolar teeth were selected, each with two distinct constricted and straight canals. Every tooth was positioned in a standing position on a platform attached to a force analysing device after access cavity preparation (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY, USA). Until the K file size was up to 15, the glide route was prepared manually. Then, using an R25/RB25 file, all of the groups' canals were completely shaped (0.08 taper, size 25). The canal was shaped with a mild and steady pressure on the file that produced a gradual, 2 mm amplitude "in-and-out" movement. It took three attempts for the file to successfully reach the WL. The canal was irrigated and recapitulated with sodium hypochlorite (1%) solution following each insertion. The Student's t-test was used to analyze the shaping time. The Mann Whitney test was applied to analyse the upward and inward peak forces. With a 95% level of confidence, SPSS software was used for all statistical analyses. Results: A single file was inserted into each root canal successfully three times for shaping till the WL achieved. With each additional file insertion, the overall real-time force increased in each group grew. The R group displayed lower peak forces in comparison to the RB group in the 3 insertions, and both groups inward peak forces varied from 1.76 to 8.64 N. (P&lt;0.05). Complete canal shaping of the RB and R systems took an average of 24.30±3.98 s and 21.91±3.56s, respectively (P&gt;0.05). During canal shaping in this experiment, no file fracture occurred. Conclusion: The forces generated during canal shaping were influenced by the blue heat treatment. Higher inward peak forces were higher in the RB file than the R file. Keywords: Root canal preparation, Endodontics, vertical force and shaping time.

Semicircular canal shape diversity among modern lepidosaurs: life habit, size, allometry

BackgroundThe shape of the semicircular canals of the inner ear of living squamate reptiles has been used to infer phylogenetic relationships, body size, and life habits. Often these inferences are made without controlling for the effects of the other ones. Here we examine the semicircular canals of 94 species of extant limbed lepidosaurs using three-dimensional landmark-based geometric morphometrics, and analyze them in phylogenetic context to evaluate the relative contributions of life habit, size, and phylogeny on canal shape.ResultsLife habit is not a strong predictor of semicircular canal shape across this broad sample. Instead, phylogeny plays a major role in predicting shape, with strong phylogenetic signal in shape as well as size. Allometry has a limited role in canal shape, but inner ear size and body mass are strongly correlated.ConclusionsOur wide sampling across limbed squamates suggests that semicircular canal shape and size are predominantly a factor of phylogenetic relatedness. Given the small proportion of variance in semicircular canal shape explained by life habit, it is unlikely that unknown life habit could be deduced from semicircular canal shape alone. Overall, semicircular canal size is a good estimator of body length and even better for body mass in limbed squamates. Semiaquatic taxa tend to be larger and heavier than non-aquatic taxa, but once body size and phylogeny are accounted for, they are hard to distinguish from their non-aquatic relatives based on bony labyrinth shape and morphology.

Evaluation of root canal morphology of mandibular central and lateral incisor in Mosul city by using CBCT

Background: Lower incisor endodontic treatment failures are primarily due to missing canals, notably the lingual canal. Aim: The incisors' root architecture and the number of canals of the mandibular would be evaluated using computed tomography using a cone beam (CBCT). Methods: 220 patients with age (18-75) years who visited Al Noor Dental Center in Mosul over the course of two years had their 780 central and lateral incisors of the jaw evaluated using 3D CBCT images. The classification of the Vertucci system was applied to determine how the root canal was shaped. Results: A comparison between the incisors of lateral and central canal shape using the Vertucci method, the number of central incisors with only one root was higher than the lateral incisors with the roots of the same number. Where it was found that the central incisors of the first type are 377 teeth, while the number of incisors Lateral 358, the number of incisors in the second type was 5 teeth, and the lateral 3 teeth. Conclusions: The root morphology of the sexes differs significantly. Various morphological alterations should be anticipated by the dental professional when undertaking endodontic treatment. To ascertain the morphological traits of the conductor's anterior tooth roots, additional research is required.

Maxillary Canine with Two Root Canals

Compared to other teeth, the maxillary canines have fewer anatomical variations. Among the primary causes why root canal therapy fails is the inability to locate and manage an additional channel or canals. Therefore, it is important to take root canal shape and variations into account for successful and effective endodontic therapy. This article explains the retreatment of a 48-year-old male patient who had an extra canal (Type II of Vertucci’s classification) found and repaired due to anatomical changes in his permanent left canine.

Investigation of the efficacy of different Ni-Ti systems on acrylic blocks for correcting ledge formation

BackgroundThe aim of this study was to compare the efficacy of K-type stainless steel hand instruments (Mani Inc. ), Fanta AF™ Ledge Correction (LC) (Fanta Dental), and Hyflex EDM (Coltene-Whaledent) for ledge correction, canal transport, centric ability, and shaping (preparation) time after an artificial ledge has been bypassed manually in highly curved canals using acrylic blocks.MethodsForty-two resin blocks, each with a radius of 5 mm (Endo Trainer Block, VDW) and an apical inclination of 55°, were used. Under stereomicroscope magnification, standard artificial ledges were created on acrylic blocks, and attempts were then made to eliminate them using hand instruments, FantaAF™ LC, and Hyflex EDM. Before and after images were obtained using a stereomicroscope and compared using Photoshop.ResultsFanta AF™ LC and Hyflex EDM were found to be more effective for correcting ledges than hand instruments. The use of hand instruments resulted in the greatest transportation away from the canal curvature in the apical area. The canal shaping was completed in the shortest amount of time using Fanta AF™ LC, followed by HyFlex EDM and then the hand instruments.ConclusionIn terms of centric ability, the order from best to worst is as follows: Fanta AF™ LC, Hyflex EDM, and hand instruments. After the ledge was manually bypassed with hand instruments in the root canals, Hyflex EDM and Fanta AF™ LC were found to be more effective than hand instruments in reshaping the previously unreachable region between the ledge and the foramen apical.

Opto-magnetic imaging spectroscopy in analyzing rotary NiTi endodontic instruments

Intra-canal fracture of rotary NiTi instruments occurs due to torsional stress, cyclic fatigue, or a combination of these two factors. Broken instruments are a serious obstacle to shaping, cleaning, and filling of the root canal and can adversely affect the outcome of endodontic therapy.The aim of this study was to examine the magnetic properties and ultrastructural changes of new, used, and fractured NiTi instruments using opto-magnetic imaging spectroscopy (OMIS). The study included three sets of different types of rotary instruments: MTwo (VDW, Munich, Germany), Pro Taper Universal (Dentsply Maillefer, Ballaigues, Switzerland), and BioRace (FKG DENTAIRE Swiss Dental Products, Le Crêt-du-Locle Switzerland). Root canal shaping was performed on root canals with different curvatures, and after intra-canal fracture, instruments of the same type (new, used, and fractured) were analyzed using OMIS at the Faculty of Mechanical Engineering, University of Belgrade.The obtained results showed a coincidence of peak localization for the used instruments that did not suffer a fracture, as well as for new, unused instruments of all examined groups. Additionally, there was a coincidence of peak intensities for new and fractured instruments in all groups. The specific treatment of electropolishing of the active surface of BioRace instruments caused a completely different electromagnetic response compared to conventional NiTi sets of tested instruments. New, unused BioRace instruments had the most pronounced positive (5.6078 n.a.u. x1000) and negative (−8.5218 n.a.u. x1000) intensity values.The analysis of NiTi instruments using opto-magnetic imaging spectroscopy indicated changes in the magnetic properties after their instrumentation.

Comparison of the effect of different glide path files on amount of apically extruded debris in curved root canals.

It is essential to create a glide path before root canal preparation with nickel-titanium rotary files to avoid file breakage and preserve the original canal structure. The aim of this study was to compare the amount of apically extruded debris after using different glide path files. A total of 96 first mandibular molars with curved mesial roots were randomly divided into six groups (n=16) which are K-files, Proglider, R-Pilot, TruNatomy Glider, WaveOne Gold Glider and group without a glide path. Apically extruded debris was measured after glide path and canal preparation. The highest amount of debris was found in the control group without a glide path and using a glide path file caused less debris and significant differences were observed between R-Pilot, TruNatomy Glider, ProGlider, WaveOne Gold Glider and K-file groups. It may be recommended to create a glide path before root canal shaping to reduce the amount of extrusion debris from the apical. Especially in curved and narrow root canals, it is recommended to use an R-Pilot file before root canal shaping in order to reduce the amount of apically extruded debris.

Apicoectomy for Periapical Lesion Treatment after Post Endodontic Failure on First Maxillary Premolar (Case Study)

Introduction. Factors that cause failure of endodontic therapy include incomplete cleaning and shaping of root canals and unhermetic obturation. Endodontic failure can lead to periapical lesions. Apicoectomy is one of endodontic surgery treatment choice to preserving the tooth with endodontic treatment failure. Aim. The aim of this report was to show that in cases of failure of root canal treatment could be treat without extraction, however there was an alternative treatments such as apicoectomy that could be used to preserve the tooth and its function in the oral cavity.Case. A male 32 years old patient came to dentist with persistent pain on upper left first premolar. The tooth had been endodontically treated for ten years. Clinical examination tooth #24 had porcelain fused to metal on it, percussion test (+), bite test (+), pain on palpation. Radiographic examination showed that tooth #24 had fabricated post without gutta percha obturation on apical third. There was 3 mm round periapical lesion on the distal side of the tooth. Procedure Apicoectomy and retrograde filling with Mineral Trioxide Aggregate (MTA) and bone graft was performed to eliminate that periapical lesion. Conclusion Apicoectomy is one of main choice to preserve post endodontic tooth with periapical lesion and post core crown on it, as long as possible in oral cavity Keywords : Apicoectomy, Periapical lesion, Post endodontic treatment failure

Effect from Autoclave Sterilization and Usage on the Fracture Resistance of Heat-Treated Nickel–Titanium Rotary Files

This study aimed to assess the effect of mechanical loading and heating on the cyclic fatigue and torsional fracture resistances of heat-treated nickel-titanium files after usage and autoclaving. Sixty files (One Curve) were tested for cyclic fatigue and torsional fracture resistances using customized devices. The files were divided into three groups according to the test conditions (n = 10); new (group-N), used for simulated canal shaping (group-U), and sterilized after use (group-S). For cyclic fatigue resistances, the files were freely rotated in a curved metal canal under body temperature; the time elapsed to fracture was recorded and the numbers of cycles to fracture (NCF) were calculated. For the torsional resistances, the file tip was fixed and rotated until the file fractured. The maximum torsional load and distortion angle were recorded. The toughness was calculated. Fracture fragments were examined with a scanning electron microscope. Data were analyzed using a one-way analysis of variance and Tukey's post hoc test at the significance level of 95%. Group-U showed significantly higher NCF than group-S (p < 0.05). However, there was no significant differences between groups-N and -S in the NCF (p > 0.05). Group-N showed a significantly bigger distortional angle and higher torsional toughness than groups-U and -S, but the ultimate torsional strength did not have significant difference between the groups. Under the limitation of this study, autoclave sterilization after single-usage did not improve the fracture resistance of heat-treated One Curve nickel-titanium files.

Anatomical variation of the incisive canal: A CBCT study at Universitas Airlangga Academic Dental Hospital

Incisive canal located in maxillary anterior of hard palate around maxillary central incisor region that acts as a tunnel between the oral cavity and the nose. Incisive canal provide sensory innervation to the nasal septum and the anterior mucosa of the hard palate. The anatomical shape of the incisive canal varies individually, hence, should be considered before surgical intervention in the oral cavity. To determine the distribution of anatomical variations of the incisive canal in the sagittal section at Universitas Airlangga Academic Dental Hospital using Cone Beam Computed Tomography (CBCT). Fifty-four samples were obtained from the interpretation report of sagittal section of CBCT at Universitas Airlangga Academic Dental Hospital from 2015 – 2021. Observations of the incisive canals were carried out by agreement of authors by classifying the variations into cylindrical shape, funnel shape, banana shapes and hourglass shapes. In 54 samples with an age range of 12 - 70 years, the variations of the incisive canal were Cylindrical shape (63%), Banana shape (19%), Funnel shape (17%) and Hourglass shape (2%). Based on gender, Cylindrical shape was most commonly found in men (56%) and women (73%). Four variations of anatomical variations of the incisive canals were found at Universitas Airlangga Academic Dental Hospital, with cylindrical shape as the most prevalent variation. Therefore, observation of the incisive canal anatomy is necessary before surgical intervention.

Fracture incidence of waveone gold and reciproc blue files when used in up to three clinical cases: a prospective study

Objective: Reuse of endodontic files remains an open issue in clinical practice. This study was designed to evaluate the fracture strength of WaveOne Gold (Dentsply Maillefer, Ballaigues, Switzerland) and Reciproc Blue (VDW, Munich, Germany) files with successive reuse for root canal shaping in up to three molars. Material and Methods: Prospective clinical study carried out by five calibrated endodontists who treated 384 molars (1291 canals) with a curvature &lt;45° over a 12-month period. A total of 128 instruments were used (64 Reciproc Blue and 64 WaveOne Gold). Each instrument was used to treat three posterior teeth. After each use, the instruments were observed under an operating microscope at 8× magnification. Data were tabulated and a chi-square test was applied. Significance was accepted at the 5% level. Results: Two instruments (one from each group) separated, both on the third use and during instrumentation of a mandibular first molar. In other words, instrument separation occurred in 0.52% of teeth and 0.16% of treated root canals. Conclusions: There was a low incidence of instrument fracture when reciprocating files were used for up to three endodontic treatments in molars.

Comparative evaluation of working length determined using integrated apex locator and root ZX mini under various irrigating solutions: An in vivo study.

Electronic apex locators (EALs) are frequently used as adjuvant to radiographs in working length (WL) determination. The introduction of integrated apex locators (IALs) further simplified the root canal treatment by continuous monitoring of the apex while root canal shaping. The aim of this study was to evaluate the efficacy of radiographs, EAL, and IAL in determining the WL in the presence of various irrigants. The present in vivo study was carried out on 30 patients who were divided into 10 in each group, based on the type of irrigant used; 0.9% saline (Group 1), 0.2% chlorhexidine (Group 2), and 2.5% of sodium hypochlorite (NaOCL) (Group 3). In each group, WL is determined using conventional radiographs, Root ZX Mini (EAL), and CanalPro CL2i (IAL). Kruskal-Wallis test and Friedman's two-way ANOVA test were used for statistical analysis. Mean WL was comparably lower with Root ZX Mini, while the WL by CanalPro CL2i and the radiographic method were comparable. In all methods, the type of solutions used did not influence the WL, with a higher mean WL when NaOCL is used as an irrigant. Nevertheless, the above comparisons were not statistically significant. the irrigation solutions employed in this study had no impact on the performance of apex locators and radiographs.

Radicular Intracanal Splitting Forces and Cutting Efficiency of NiTi Rotary Versus Reciprocating Systems: A Comparative In Vitro Study

This study aimed to compare the intracanal lateral force and cutting efficiency associated with two engine-driven nickel-titanium (NiTi) systems during root canal shaping. Bovine single-rooted teeth models were assembled to a custom-made splitting force measuring platform while being endodontically treated with rotary (ProTaper Gold [PTG]) or reciprocal systems (WaveOne Gold [WOG]) by two clinicians. The cutting efficiency test was run for each group by a free-falling endomotor on dentin discs for 3 min. The resulting force, files, and stroke force peaks were recorded. Data were analyzed by the Shapiro-Wilk test and ANOVA. Statistical significance was set at alpha = 0.05. Intracanal lateral forces (p &lt; 0.01), cutting efficiency (p &lt; 0.01), and time efficiency (p &lt; 0.01) were significantly different between the NiTi groups. The maximum lateral splitting force was detected using the PTG shaping full-length file (S1) and during the WOG final stroke. Thus, caution is advised when reciprocating single-file systems approach the apical third or when using a large taper and wide-diameter rotatory instruments. The WOG had significantly less maximum horizontal splitting force and significantly greater cutting efficiency but less time efficiency than the PTG system.

Effect of Real-Ear Adjusted Stimuli on Vestibular Evoked Myogenic Potential Variability in Children and Young Adults.

There is large variability in cervical and ocular vestibular evoked myogenic potential (c- and oVEMP) amplitudes. One potential source of variability is differences in ear canal shape and size. Real ear-to-coupler difference (RECD) values are used to measure the acoustic environment of an individual's ear canal. RECD may be a useful measure to calibrate air conducted VEMP stimuli, which are elicited at high intensities and may put patients at risk of unsafe sound exposure. A recommendation for avoiding unsafe exposure is to use a 125 dB SPL stimulus for individuals with an equivalent ear canal volume (ECV) ≥ 0.9 mL and a 120 dB SPL stimulus for individuals with a smaller ECV. The purpose of this project was to determine if using a stimulus calibrated in the ear using RECD values significantly reduces intra-subject and inter-subject VEMP amplitude variability. We hypothesized that using a RECD-calibrated stimulus would significantly reduce inter-subject amplitude variability but not significantly reduce intra-subject variability. We further hypothesized that an RECD-adjusted VEMP stimulus would better protect against delivering unsafe sound exposure compared to the method of using ECV alone. Eleven children (4 to 9 years), 10 adolescents (10 to 18 years), and 10 young adults (20 to 40 years) with normal hearing, tympanometry, vestibular and neurological function participated. On all subjects, RECD was measured twice per ear to account for test-retest reliability. cVEMP and oVEMP were then recorded bilaterally with a 500 Hz tone burst at a traditional and an adjusted VEMP intensity level. The traditional intensity level was 125 dB SPL for individuals with ≥ 0.9 mL ECV and 120 dB SPL for individuals with ≤ 0.8 mL ECV. The adjusted intensity level was calculated by subtracting the average 500 Hz RECD measured values from the 500 Hz normative RECD value. This value was applied as a correction factor to a 125 dB SPL stimulus. Peak to peak amplitudes were recorded and used to calculate asymmetry ratios. Young children had significantly smaller ECVs compared to adolescents and young adults. Young children had larger RECDs; however, this was not significant in post hoc analyses. The method of calibration had no significant effect on intra-subject variability for cVEMP [ F (1, 27)= 0.996, p = 0.327] or oVEMP [ F (1, 25)= 1.679, p = 0.206]. The method of calibration also had no significant effect on inter-subject amplitude variability for cVEMP [ F (1, 120)= 0.721, p = 0.397] or oVEMP [ F (1, 120)= 0.447, p = 0.505]. Both methods of calibration adequately protected against unsafe exposure levels. However, there were subjects with ECVs ≥ 0.9 mL who approached unsafe exposure levels from the ECV-calibrated stimulus, suggesting there may be rare cases in which a 125 dB SPL stimulus is unsafe, even for patients with larger ECVs. The calibration method made no significant difference in intra- or inter-subject variability, indicating that the acoustic environment of the outer ear is not significantly contributing to VEMP amplitude variability. The RECD-adjusted stimulus is effective in protecting against unsafe exposure levels for two trials of both c- and oVEMPs. There may be instances where more than two trials of each test are required, which increases the effective stimulation level. Clinicians should be cautious when delivering VEMPs and not unnecessarily expose patients to unsafe levels of sound.

CBCT assessment of dentin thickness of lower incisors after shaping with NiTi instruments – in vivo study

Remaining root dentin thickness plays a key role in the longevity of endodontically treated teeth. Purpose: The aim of this study was to compare the root canal wall thickness in the danger zones of mandibular incisors before and after their instrumentation with two different NiTi rotary systems by means of CBCT. Methodology: Thirty lower incisors of patients aged 45 – 55 years underwent primary endodontic treatment with two NiTi files systems: ProTaper Universal and WaveOne Gold. The changes of the root canal thickness in the danger zones of the incisors were investigated by two CBCT scans – one at the beginning of the experiment and the other after the shaping of the root canals. Results: Shaping of the root canals of lower incisors with the two NiTi systems significantly decreased the mesio-distal root dentin thickness in all root canal levels when compared with the baseline values (p≤0.001). NiTi files from both experimental groups removed substantially more root dentin in the coronal portion of the root than in the apical (p&lt;0.05). The intergroup comparison between the two tested NiTi systems revealed no statistically significant difference in their performance at the three observation levels (p&gt;0.05). Conclusions: Both NiTi systems performed equally and removed dentin more aggressively in the coronal portion of the root. Further clinical experiments are necessary to find the minimally invasive endodontic systems for an optimal preservation of root dentin in the danger zones of mandibular inciso

The Influence of Thermomechanical Compaction on the Marginal Adaptation of 4 Different Hydraulic Sealers: A Comparative Ex Vivo Study

Since there are no data in the literature regarding the comparison of the marginal adaptation of hydraulic sealers when used with a single-cone technique or through thermomechanical compaction, this study aimed to evaluate the behavior of four different endodontic sealers used with the two above-mentioned obturation techniques by evaluating the marginal gap existing between the obturation materials and the dentinal walls through scanning electron microscopy. Given this objective, a total of 104 single-rooted, straight canal teeth were selected and divided into four subgroups according to the selected endodontic sealer ((AH) Plus Bioceramic Sealer (AHP), EndoSequence BC Sealer HiFlow (ES), C-Root SP (CR), and GuttaFlow Bioseal (GF)). Each tooth was decoronated and instrumented with the HyFlex EDM/CM systematics up to 30.04. After irrigation procedures, the teeth of each subgroup were divided into two groups and obturated according to two different obturation techniques: the single-cone technique (SC) and the thermomechanical compaction technique (TC). After the required sealer setting time, each tooth was sectioned in three parts at 3, 6, and 9 mm from the apex, and each section was observed with a scanning electron microscope. The marginal gap of each sample was measured using G* Power Software v3.1, and the statistical analysis was performed using the Kruskal–Wallis test, followed by a post hoc Dunn’s test. Results showed that there were not any statistically significant differences in terms of the marginal gap between the two different above-mentioned obturation techniques for each sealer, except for the middle third of root canals, where a statistically significant difference was found for AHP, ES, and GF sealers. In conclusion, the thermomechanical compaction of hydraulic sealers and gutta-percha guarantees better sealing than the single-cone technique when the root canal shape is not rounded.

Tetrastigma hemsleyanum Diels et Gilg Roots from Different Origins: Pharmacognostical Identification, Content Determination of Functional Composition and in vitro Antioxidant Activity

Tetrastigma hemsleyanum Diels et Gilg (T. hemsleyanum) is a unique and rare Chinese medicinal herb mainly distributed in the south of the Yangtze River in China. In the present study, T. hemsleyanum roots from seven different sites in the south of the Yangtze River (Guangxi [Baise, Guilin, and Hechi], Hunan [Fenghuang], and Zhejiang [Hangzhou, Taizhou, and Wenzhou] provinces) were collected, and differences in the macroscopic and microscopic appearance of the roots, content of their active ingredients, and antioxidant activity of the root extracts were analyzed. The Pearson correlation coefficient was used to analyze the correlation between the antioxidant activity and the total flavonoids and total polyphenols contents of T. hemsleyanum roots. The results of macroscopic and microscopic root appearance indicated that T. hemsleyanum roots from different sites could be clearly differentiated based on size and epidermal characteristics, the color of dry root powder, and the shape and arrangement of the root canal. The results of content determination showed no significant differences (P>0.05) between the contents of flavonoids, polyphenols, rutin, and catechin in T. hemsleyanum roots from Guilin, Guangxi, and those from Zhejiang and Hunan. However, the contents of quercetin and kaempferol showed a significant difference (P<0.01) between T. hemsleyanum roots from Guilin, Guangxi, and those from Zhejiang, Hunan, and Guangxi (Baise and Hechi). Furthermore, the root extracts of T. hemsleyanum showed a high antioxidant activity ranging from 2.254±0.240 to 14.655±4.528 mg ascorbic acid equivalent/g sample. Pearson correlation analysis showed that the antioxidant activity of T. hemsleyanum roots had a higher correlation with the total flavonoids content than with the total polyphenols content. The results of this study provided a reference for the quality evaluation of T. hemsleyanum from different origins and provided technical support for subsequent resource development.