Impact of Sequential Use of Reciprocating Files on the Shaping Load During Root Canal Treatment.

INTRODUCTION: The purpose of this in vitro study was to investigate the apical and coronal loads generated during shaping canals with 2 successive reciprocating files in comparison to a single reciprocating file from the same system. METHODS: A total of 40 narrow and straight canals were distributed into two groups: R-Motion with single file (RMS) and R-Motion with multiple files (RMM). In both groups, the R-Motion system was used in a reciprocating motion. After establishing glide path, the RMS canals were shaped down to working length with a single file (25/.06) in two insertions while the RMM canals were shaped with two files (20/.04 and 25/.06) to the working length. The shaping time and effects of tested groups on the apical and coronal peak loads were statistically analyzed using the t-test and Mann-Whitney U test, respectively, at a 95% confidence level. RESULTS: All canals were completely shaped in three insertions and no file deformation or fracture was observed. The RMS and RMM were able to shape canals in 117.3 ± 15.1 and 123.7 ± 7.3 seconds, respectively (P < .05). Within each group, the shaping load appeared to increase with the successive insertions of the file. In both groups, the ranges of apical and coronal peak loads were 0.41-1.87 N and 0.38-1.03 N, respectively. The RMM and RMS had comparable apical and coronal peak loads (P > .05) except in the last insertion where RMM showed clearly lower apical peak load than RMS (P < .01). CONCLUSIONS: Under the current laboratory conditions using the R-Motion system, preshaping the canal with a smaller reciprocating file was shown to favorably reduce the apical peak loads induced during canal shaping of extracted teeth.

Impact of cooling on shaping ability of thermally treated files in canal models with double curvature.

Background: This study compared the ability of thermally treated files in shaping simulated canals with double curvature. Fifty-six canals were enlarged to a final size of 25 with ProTaper Next (PTN) or ZenFlex (ZF). Materials: Half of the samples were shaped with cooled files (n = 14 each). The amount of removed resin was measured and canal deviation was determined at eight levels. Shaping time and maximum shaping torque values were also recorded. Data were statistically analyzed using analysis of variance and LSD, Kruskal-Wallis, and chi-square tests at a 0.05 significance level. Results: Compared to PTN and cooled PTN, ZF and cooled ZF required lesser time to shape the canals. The maximum torques were found comparable between the groups. All the groups generated negligible deviations at every canal level evaluated and maintained the canal geometry. Although not significant, the cooled PTN and ZF files exhibited lesser canal deviations than their counterparts. Conclusion: All groups demonstrated similar shaping ability whilst maintaining the original curvature of the canal in simulated canals with double curvature. However, ZF groups were able to shape the canals faster than PTN groups. There was a trend that cooled files made lesser canal deviations compared to their counterparts.

Retreatment of oval-shaped root canals filled with TotalFill bioceramic or AH plus sealer.

This study investigated retreatment of oval canals filled with gutta-percha and different sealers using WaveOne Gold (WOG). Single oval canals were prepared to size 30, 0.04 and obturated with gutta percha and AH Plus (AHP) or TotalFill bioceramic (TFBC) sealer. After 6-month incubation, the canals were retreated with WOG Primary (25, 0.07) under simulated body temperature, and the developed load and torque were simultaneously measured. The time and regaining the apical patency were checked. Micro-computed tomography scanning was performed to calculate the remaining obturating materials. An independent t-test and chi-square test were performed at a 95% confidence level. A shorter retreatment time was needed in TFBC than in AHP (P = 0.003). However, a higher maximum apical load was reported with AHP (P = 0.000). Meanwhile, comparable maximum coronal load and maximum torque values were observed. Apical patency was regained in all TFBC roots and only 75% of the AHP samples (P = 0.217). The remaining obturating materials were comparable in TFBC (13.02 ± 8.12%) and AHP (10.11 ± 8.46%) (P = 0.398). WOG was able to remove 89.89% and 86.98% of obturating materials in TFBC and AHP, respectively. The TFBC presented lower apical loads and faster retreatment compared to AHP.

Developments and Performance of Artificial Intelligence Models Designed for Application in Endodontics: A Systematic Review.

Technological advancements in health sciences have led to enormous developments in artificial intelligence (AI) models designed for application in health sectors. This article aimed at reporting on the application and performances of AI models that have been designed for application in endodontics. Renowned online databases, primarily PubMed, Scopus, Web of Science, Embase, and Cochrane and secondarily Google Scholar and the Saudi Digital Library, were accessed for articles relevant to the research question that were published from 1 January 2000 to 30 November 2022. In the last 5 years, there has been a significant increase in the number of articles reporting on AI models applied for endodontics. AI models have been developed for determining working length, vertical root fractures, root canal failures, root morphology, and thrust force and torque in canal preparation; detecting pulpal diseases; detecting and diagnosing periapical lesions; predicting postoperative pain, curative effect after treatment, and case difficulty; and segmenting pulp cavities. Most of the included studies (n = 21) were developed using convolutional neural networks. Among the included studies. datasets that were used were mostly cone-beam computed tomography images, followed by periapical radiographs and panoramic radiographs. Thirty-seven original research articles that fulfilled the eligibility criteria were critically assessed in accordance with QUADAS-2 guidelines, which revealed a low risk of bias in the patient selection domain in most of the studies (risk of bias: 90%; applicability: 70%). The certainty of the evidence was assessed using the GRADE approach. These models can be used as supplementary tools in clinical practice in order to expedite the clinical decision-making process and enhance the treatment modality and clinical operation.

Tinnitus Prevalence and Associated Factors among Dental Clinicians in the United Arab Emirates.

Dental clinicians are at increased risk for developing tinnitus due to exposure to high levels of occupational noise. This study aimed to determine tinnitus prevalence and associated factors among dental clinicians. Interviews were conducted with 150 randomly selected dental clinicians using a questionnaire. Noise levels were measured at three points of time at the operating area. Tinnitus was reported in 19.33% of the participants. The average noise level was significantly higher among participants with tinnitus compared to those without the condition. More participants complained of intermittent tinnitus and the rest had the constant type, with the latter being significantly more bothersome. The weekly average time of using high-speed handpieces, suction and electric handpieces, age and experience had a significant effect on the presence of tinnitus. Only 2.7% of the participants reported the use of a hearing protection device. Tinnitus is a common finding among dental clinicians especially those with higher levels of occupational noise and more frequent use of noise-generating equipment. Knowledge of tinnitus prevalence aids in realizing the extent of its impact and making informed decisions. These results call for improved awareness of the negative impact of clinically-generated noise and emphasize the importance of preventive measures and periodic audiometry exams.

Effect of phytic acid on dentinal collagen solubilization and its binding and debinding potentials to dentin.

OBJECTIVES: To study phytic acid (IP6) effect on collagen solubilization by assessing hydroxyproline (HYP) release, evaluate its binding to demineralized (DD) and mineralized dentin (MD) and determine the effect of different media on debinding of IP6. METHODS: Demineralized dentin beams were incubated in 1%, 2% or 3% IP6 and HYP release was evaluated at 1 or 3 weeks and compared to those obtained in untreated control or phosphoric acid (PA)-treated beams. DD or MD powder was treated with 1%, 2% or 3% IP6 and the decrease in IP6 amount was quantitated by ultraviolet-visible spectroscopy. IP6-treated samples were re-suspended in distilled water, ethanol, urea or sodium chloride and the amount of IP6 displaced was determined. RESULTS: At 1 week, the control group and IP6 showed lower HYP release when compared to PA (P < 0.05). There was no difference among PA, IP6 and control at 3 weeks (P = 0.22). IP6 binding was concentration dependent. 1% IP6 had higher binding potential with MD compared to DD while 2% IP6 showed the opposite result (P<0.05). 3% IP6 had similar binding values between DD and MD (P = 0.53). The highest debinding in MD occurred with urea for 2%, 3% and 1% IP6 in descending manner. Within each concentration of IP6 in DD, the highest debinding effect was reported with ethanol. CONCLUSIONS: IP6 bound to DD and MD in a concentration-dependent manner. IP6 was debound from DD mostly by the action of ethanol, while in MD, urea caused the most displacement. Collagen solubilization of IP6-treated DD was comparable to untreated DD. CLINICAL SIGNIFICANCE: These findings add to the potential use of IP6 as an alternative to PA for dentin etching which possibly results in long-term stability of resin-dentin adhesion.

Chlorhexidine as a Disinfectant in the Prosthodontic Practice: A Comprehensive Review.

INTRODUCTION: Controlling the cross-contamination between the dental clinic and laboratory is of utmost importance to maintain the health of dental healthcare personnel (DHCP) and patients. The aim of this paper was to review the current literature with regard to the use of chlorhexidine as a prosthetic disinfectant in prosthodontic practice. MATERIALS AND METHODS: A scoping review of the literature was performed in Medline/PubMed, Ovid Embase, and the Cochrane Library. A search for all literature published from 1980 to 2021 was based on the following keywords: ['Chlorhexidine/gluconate' OR 'chlorhexidine', OR 'gluconate', OR 'denture disinfectants', OR 'antimicrobial', OR 'disinfectant', OR 'impression disinfectants, OR prosthesis' OR 'biofilm, microbiology'] OR [teeth]. We reviewed the disinfectant in terms of its mechanism of action, antimicrobial effectiveness, disinfection techniques, clinical applications, corrosiveness/damage to the structure of prostheses, and reasonable shelf life. RESULTS: Chlorhexidine was tested under different concentrations ranging from 0.2 to 5%. It provided a significant reduction in biofilm viability but had a minimum effect on Candida albicans with a variable effect result that showed no significant differences in the dimensional changes by immersion of alginate dental impressions for no more than 10 minutes and no clinically significant dimensional differences on aluwax, polyether, condensation siloxane, and polyvinyl siloxane were noticed. Nonetheless, chlorhexidine altered the surface of the silicone and acrylic resins and affected the long-term hardness of the relining material. CONCLUSION: Within the limitations of this review, the use of chlorhexidine disinfectant demonstrates a good measure in the reduction of contamination and cross-infection and has a minimal effect on the dimensional stability of most impression materials. Further studies with in-vitro testing are required to confirm these findings.

Effect of Blue Heat Treatment on Vertical Force Induced with Endodontic Files.

OBJECTIVE: To evaluate the vertical forces induced with Reciproc (R) and Reciproc Blue (RB) systems during canal shaping. METHODS: Maxillary premolar teeth with two separate straight and constricted canals were chosen (n=26). After access cavity preparation, each tooth was fixed in a standing position on a stage connected to a force analyzing device (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY, USA). The glide path was prepared manually until K file sizes #15. Then, canals in all the groups were completely shaped with an R25/RB25 file (size 25,.08 taper). The canal shaping was done with a steady and gentle pressure on the file to give a slow 'in-and-out' movement of 2 mm amplitude. The file was inserted three times until it reached the WL successfully. After each insertion, the canal was recapitulated and irrigated with a 1% sodium hypochlorite solution. The shaping time was analyzed by Student's t-test. The inward and upward peak forces were used for analysis by using the Mann-Whitney test. All statistical analyses were performed using SPSS software at a 95% confidence level. RESULTS: Each root canal was shaped successfully with a single file inserted three times until the WL was reached. Within each group, the overall real-time force increased with the successive insertions of the file. The inward peak forces in both groups ranged from 1.71 to 8.38 N and the R group showed minimal peak forces than the RB group in the three insertions (P<0.05). The upward peak forces ranged from 1.50 to 3.26 N wherein both groups showed comparable peak forces at each insertion (P>0.05). The R and RB systems required average times of 22.01±3.08 and 23.93±4.15 s, respectively, to shape the canals completely (P>0.05). In this experiment, no file fracture took place during canal shaping. CONCLUSION: The blue heat treatment influenced the forces developed during canal shaping. RB file was associated with higher inward peak forces than R file.

Fiber Post Removal Using a Conservative Fully Guided Approach: A Dental Technique.

This report describes the usefulness of an endodontic template for the removal of a fiber post. A 40-year-old man presented with discomfort in the maxillary left canine. Clinical and radiographic examinations showed tooth #23 with a permanent core material retained with fiber post along with a persistent apical radiolucency. Among the various treatment modalities, nonsurgical root canal retreatment with fiber post removal using a conservative fully guided approach was proposed. After obtaining both the cone-beam computed tomographic images and the cast surface scan, their data were merged using implant planning software (ImplaStation for Windows x64 Bit Beta Version, ProDigiDent, Miami, Florida, USA) and superimposed. The drilling space was planned based on the location, diameter, and apical extent of the fiber post and was virtually overlapped and transferred clinically using a resin template to drill through the fiber post. With guides in position over the rubber dam, drilling was made with increments of 2 mm using a size 4 long-shank round bur (Thomas, Bourges, France) until it exposed the coronal gutta-percha. As soon as the canal was located, K3 rotary files (Sybron Endo, Orange, USA) were used along with chloroform to remove the old obturating materials. Then, additional shaping and cleaning were done with ProTaper Next rotary files (Dentsply Sirona, Ballaigues, Switzerland), sizes X2 and X3, and 5.25% NaOCl irrigation, respectively. The root canal was then dried with paper points and obturated with gutta-percha and AH Plus sealer (Dentsply Sirona, Ballaigues, Switzerland) using the continuous-wave compaction technique. Finally, the tooth was temporarily restored using the double seal technique with zinc oxide and zinc sulfate-based temporary material (Cavit W; 3M ESPE, St. Paul, MN, USA) and resin-modified glass ionomer material (Photac Fil; ESPE, Norristown, PA, USA) filling materials and referred for the final restoration.

Assessment of the educational value of endodontic access cavity preparation YouTube video as a learning resource for students.

OBJECTIVE: To evaluate the educational value of YouTube as a learning tool for dental students regarding endodontic access cavity preparation. METHODS AND FINDINGS: YouTube search was made for videos related to endodontic access cavity preparation using specific terms. After exclusions, 41 videos were chosen and assessed for tooth type, video length, days since upload, country of origin, number of views and likes, source of authorship, and viewing rate. To grade the content of videos, a usefulness score with seven elements was developed. Each element was given a score of 0 or 1. Statistical tests were run by using Kruskal-Wallis and Mann-Whitney tests (SPSS Inc, Chicago, IL, USA) at a 5% significance level. The videos received a mean of 181198.5 views with a mean duration of 686.1 seconds. The mean number of "likes" was 1047.8. Almost half of the videos covered content related to molar teeth. Most videos were provided by health care professionals with almost 50% uploaded from India. The mean usefulness score was 4.29 (range: 1-7) and the most discussed elements were description, instruments used, access cavity demonstration, and evaluation criteria. About a quarter of the videos were classified as good, while 46.3% as moderate and 29.3% as poor. Among the content usefulness categories, no difference was found in the video demographics (p>0.05) except "days since upload" (p = 0.018) in which good quality videos were found to have the highest median. Moreover, although insignificant, good videos were found to have the longest duration and lowest number of views, likes, and viewing rate. The mean usefulness score of videos released during the COVID-19 pandemic was lower than that for pre-pandemic videos (p = 0.042), and videos uploaded by academic institutions had a higher mean usefulness score than videos uploaded by health care professionals (p<0.001). CONCLUSIONS: Information on endodontic access cavity preparation is not comprehensive in most of the reviewed YouTube videos and could be of low educational value.

Assessment of Bioceramic Sealer Retreatability and Its Influence on Force and Torque Generation.

This study assesses the retreatability of TotalFill bioceramic (TFBC) and AH Plus (AHP) sealers and their impact on retreatment force and torque. Twenty-six premolar teeth with single oval canals were instrumented, obturated using the matched gutta-percha cone technique with one of the tested sealers, and then temporized. After a 6-month incubation at 37 °C and 100% humidity, the canals were retreated with the XP Shaper system. During retreatment, the generated force and torque were measured. Micro-CT scanning was run before and after the retreatment procedure to analyze the remaining obturating materials in the canals. The apically directed maximum force in AHP was higher than that in TFBC. The coronally directed maximum force and the maximum torque were comparable between the groups. A higher amount of remaining obturating materials was found in the AHP compared to that in the TFBC. Based on these findings, endodontic sealer had an influence on retreatability, and the TFBC showed less remaining obturating materials and lower retreatment forces in the apical direction compared to the AHP in extracted teeth with oval canals.

Effect of NaOCl and EDTA irrigating solutions on the cyclic fatigue resistance of EdgeTaper Platinum instruments.

BACKGROUND: To compare the solution on the cyclic fatigue resistance of EdgeTaper Platinum (ETP) instruments with that of ProTaper Gold (PTG) in the presence of ethylenediaminetetraacetic acid (EDTA) or sodium hypochlorite (NaOCl) irrigating solutions. METHODS: Sixty PTG and 60 ETP instruments with the same size (#25) and taper (8%) were tested under 17% EDTA, 5.25% NaOCl, or distilled water (n = 20 each). Cyclic fatigue was tested using artificial canals that were milled in stainless steel blocks using a laser micromachining technique. The canals had a curvature angle of 60 and a curvature radius of 5 mm. The center of maximum curvature was set at 5 mm from the instrument tip. The block of artificial canals was stabilized inside a container that was filled with one of the tested solutions. The temperature was fixed at 37 °C with a tolerance limit of 1 °C. The number of cycles to fracture (NCF) was calculated and the fractured surfaces were examined using a scanning electron microscope. All statistical analyses were performed using SPSS software Version 20 (IBM-SPSS Inc., Chicago, IL) at a confidence level of 95%. RESULTS: ETP showed higher NCF than PTG in any of the tested solutions (P < 0.05). Within each group, NaOCl drastically decreased the NCF compared to water and EDTA (P < 0.05) and changing the solution from distilled water to EDTA did not affect the fatigue resistance (P > 0.05). CONCLUSIONS: ETP showed improved cyclic fatigue performance compared to PTG in all tested irrigating solutions. EDTA can be used in combination with NiTi instruments during canal instrumentation without compromising the cyclic fatigue resistance of PTG and ETP instruments. However, NaOCl drastically decreased the NCF.

The Effect of Sealer Application Methods on Voids Volume after Aging of Three Calcium Silicate-Based Sealers: A Micro-Computed Tomography Study.

During obturation, air voids are undesirable as they may provide shelter for microorganisms or passage for fluids. This study aimed to compare the occurrence of voids between three calcium silicate-based sealers (CSBSs) (MTA-Fillapex, BioRoot-RCS, Bio-C) and the change in their volume after aging. In addition, we aimed to compare voids when using two sealer application methods: lentulo-spiral (LS) and gutta-percha (GP) cone. Thirty extracted mandibular premolars (n = 30) were endodontically prepared and obturated using single GP cone (SGPC) technique. Each sealer was applied to 10 teeth (n = 10) using LS or GP. Micro-computed tomography (micro-CT) was used to quantify the volume of root filling and voids before and after 8-week storage in a phosphate-rich medium. The percentage of root filling and voids were compared between the groups using a Mann-Whitney U test and Kruskal-Wallis test with a Bonferroni correction. Before aging, the percentages of root filling volume after obturation were comparable with no significant differences between sealers (p = 0.325) or application methods (p = 0.950). After aging, the voids' volume increased significantly in all sealers (p ≤ 0.05). However, no significant differences were found between sealers (p = 0.302). In conclusion, voids in CSBSs may not reduce in size with aging; hence, SGPC should be carefully selected for suitable cases.

Scientometric evaluation of endodontic publications by Gulf Cooperation Council region in 21st century.

OBJECTIVES: The appraisal of research productivity is one of the key indicators to evaluate any area of knowledge. The current study aimed to analyze the Scopus-indexed publications on endodontics produced by Gulf Cooperation Council (GCC) region from 2000 to 2020. METHODOLOGY: The dataset was extracted in May 2021 from Elsevier's Scopus database. Two keywords ("endodontic" and "endodontics") were entered into the basic search with the Boolean operator of OR for a period of 20 years from 2000 to 2020. RESULTS: Overall, the GCC region contributed 2.82% of the global endodontic research. This share has shown a remarkable increase between 2001 and 2020 from 0.82% to 7.20%. About 60% of documents' volumes were produced during the 2016-2020 period. Around 80% of research was produced by Saudi Arabia, while research articles produced by Kuwait gained the highest citation impact. Out of the ten productive institutions, nine belonged to Saudi Arabia and one was from Kuwait. The majority of research collaboration was conducted with the United States, but research articles produced in collaboration with Japan yielded the highest citation impact. CONCLUSION: The study highlighted various scientometric attributes of endodontic publications produced by GCC affiliated researchers. The ongoing growth of endodontic literature by GCC countries along with the increasing international collaboration is considered aspiring.

Vertical Load and Torque during Postspace Preparation and Their Influence on Microcrack Development.

PURPOSE: To investigate, in vitro, the magnitudes of vertical load and torque generated during post space preparation of root canal treated teeth and their influence on microcrack development. MATERIALS AND METHODS: Forty extracted premolars with single canals were decoronated. The roots were prepared using ProTaper Next system (Dentsply Sirona) to X3 file, obturated, and provisionalized. After a 3-week incubation period, the roots were distributed into 2 groups according to the post drill system used (ParaPost fiber post and RelyX fiber post). During post space preparation, the vertical load, torque, and preparation time were recorded. Before and after the post space preparation, the roots were imaged with micro-computed tomography (SkyScan 1172; Bruker micro-CT) to detect new microcracks. The data were analyzed using the Mann-Whitney U-test and chi-square test. RESULTS: In ParaPost and RelyX, the post space was prepared in 48.31 ±25.28 and 47.71 ±13.36 seconds, respectively (p = 0.360). The peak vertical load generated with ParaPost (20.23 ±7.80 N) was significantly lower than that of RelyX (29.43 ±5.82 N) (p = 0.010). The maximum torque attained with ParaPost (1.42 ±0.61 N.cm) was found to be significantly lower than that of RelyX (3.23 ±1.58 N.cm) (p = 0.000). No post drill fracture or visible deformation was noticed throughout the experiment. New microcracks were found in three ParaPost samples only. CONCLUSIONS: The choice of postdrill influenced the loads and torques generated during postspace preparation. The ParaPost system showed favorably lower load and torque values during the postspace preparation compared with the RelyX system.

Evaluation of YouTube videos for patients' education on periradicular surgery.

The aim of this study was to evaluate the content of periradicular surgery-related YouTube videos available for patients' education. YouTube search was made for videos related to periradicular surgery using specific terms. After exclusions, 42 videos were selected, viewed and assessed by two independent observers. The videos were assessed in terms of duration, days since upload, country of upload, number of views, likes and dislikes, authorship source, viewing rate and interaction index. To grade the content of videos about periradicular surgery, a usefulness score was created with 10 elements based mainly on the American Association of Endodontists guidelines. Each element was given a score of 0 or 1. SPSS software (SPSS Inc, Chicago, IL, USA) was used to analyze data at a 95% confidence level. An inter-evaluator reliability analysis for the scoring system was performed using the Kappa statistic. The videos received an average of 35103.9 views (range: 9-652378) with an average duration of 338.71 seconds (range: 42-2081), respectively. Most videos were provided by individuals (57%). Half of the videos were posted by authors from the United States. The inter-evaluator reliability for usefulness scoring was 94.5%. No video covered the 10 scoring elements completely, presenting very low usefulness scores (mean: 3.2; range: 1-7). The most discussed elements were supporting media (100%) and steps of the procedure (90.5%) followed by indications and contraindications (45.2%) and symptoms (31%). None of the included videos discussed the procedure's cost or prognosis. In terms of usefulness score, no significant difference was detected between different sources of upload (chi-square test, P > 0.05). Information on periradicular surgery in YouTube videos is not comprehensive and patients should not rely on YouTube as the only source of information. Dental professionals should enrich the content of YouTube with good quality videos by providing full and evidence-based information that will positively affect patients' attitudes and satisfaction.

Evidence for reduced torsional resistance of rotary files under curved position.

OBJECTIVES: The aim of this in vitro study was to investigate the torsional fatigue resistance of different rotary files in straight and curved positions at a simulated intracanal temperature. METHODS: Forty-eight size #25 files from ProTaper Universal (PTU), ProTaper Next (PTN) and ProTaper Gold (PTG) were tested for torsional resistance in both straight and curved (90 degrees) positions (n = 8 each). The experiment was conducted at a simulated intracanal temperature of 35 ± 1 °C. The torque gauge was reset before every use, and uniform torsional stress was applied by rotating the file clockwise at a speed of 40 rpm until fracture. Torque failure values were recorded, and fractured surfaces were tested using a scanning electron microscopy (SEM). Statistical analysis of the data was completed using one-way ANOVA and post-hoc test (LSD) in order to compare between the tested systems in each file position. Student's t-test was also performed to compare between the two positions in each rotary system, and significance level was set at 5%. RESULTS: In the straight position, torsional resistance of PTN was significantly lower than that of PTU and PTG (p < 0.001), while the PTU and PTG had comparable results (p > 0.05). In the curved position, torsional resistance was found to be comparable among all systems (p > 0.05). Within each system, the curved position resulted in a significantly lower torsional resistance when compared to the straight position (p < 0.001). SEM examination revealed similar torsional failure behavior for all files tested under both positions. CONCLUSIONS: Our study identified that placing files in a curved position was associated with a significant decrease in torsional resistance of all systems, and this necessitates reconsidering the torque settings proposed by the manufacturers. Whether these effects can be translated into in vivo studies remains to be investigated, and thus future studies are essential to provide confirming evidence.

Morphometric Analysis of the Mandibular Canal, Anterior Loop, and Mental Foramen: A Cone-Beam Computed Tomography Evaluation.

This study investigated the cone-beam computed tomography (CBCT)-based features of the mandibular canal, mental foramen, anterior loop, and accessory mental foramina with respect to age and sex. A total of 306 CBCT mandibular images were included in this retrospective study to measure the mandibular canal location and extension, the mental foramen position, the presence of the anterior loop, and the accessory mental foramina. The measurements were obtained in sagittal, coronal, and axial views. Descriptive statistics are presented. Sex-related differences, correlations, and comparisons were calculated using SPSS at 5% significance level. The mandibular canal was located more coronal and medial in male patients. The majority of cases had the mental foramen located just apical to the mandibular second premolar with a mean height of 2.94 mm and a mean length of 3.28 mm. Age affected the size of the mental foramen. The mental canal in all cases tended to show a coronal direction. Mesial extension of the anterior loop was found in 66.01% of the images while accessory mental foramina were detected in 2.6%. The complexity of the mandibular canal, mental foramen, anterior loop, and accessory mental foramina among Sudanese patients with respect to age and sex was confirmed.

Debris Extrusion Using Reciproc Blue and XP Endo Shaper Systems in Root Canal Retreatment.

This study aimed at assessing the performance of Reciproc Blue (RB) and XP Endo Shaper (XPS), used for canal retreatment on extracted teeth, in terms of debris extrusion and obturating materials removal. Thirty mandibular premolars were prepared to ProTaper X2 file, obturated using warm vertical compaction, and then incubated for 28 days at 100% humidity at 37°C. Teeth were randomly assigned into two groups, according to the system used for retreatment (RB and XPS). During retreatment, debris extruded beyond the apex was collected in preweighed Eppendorf tubes, and the retreatment time was measured. Afterward, the teeth were longitudinally sectioned to assess the remaining obturating materials. Data were statistically analyzed using the Mann-Whitney test and chi-square test at a 95% confidence level. All the samples had extruded debris at varying weights ranging from 0.125 mg to 3.680 mg. XPS extruded less debris than RB, but no difference was detected (Mann-Whitney test; P > 0.05). RB and XPS required 54.9 ± 17.9 and 22.3 ± 9.3 seconds to perform retreatment procedures, respectively (Mann-Whitney test; P < 0.05). The sealer was found in all the samples. Compared to the RB group, fewer samples with remaining gutta-percha were found in the XPS group (Chi-square test; P < 0.05). None of the files fractured during the retreatment procedure. The tested files appear to extrude debris beyond the apex. Although XPS was able to remove the gutta-percha completely from the majority of the canals, it was unable to remove the sealer.

Psychological Distress among Undergraduate Dental Students in Saudi Arabia and Its Coping Strategies-A Systematic Review.

The objective of this paper was to evaluate the studies that have reported on psychological issues among dental students in Saudi Arabia and to develop coping strategies to overcome these mental health-related issues. The present systematic review is in accordance with the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search for the articles was carried out in the electronic databases by four independent researchers. The data search was performed in the electronic search engines like PubMed, Google Scholar, Web of Science, Scopus, Medline, Embase, Cochrane and Saudi Digital Library for scientific research articles published from January 2000 until December 2020. STROBE guidelines were adopted for qualitative analysis of six articles which met the eligibility criteria. The analysis of the literature revealed that most of the studies included were conducted in the past 8 years in different regions of Saudi Arabia. Findings of this systematic review clearly state that dental students in Saudi Arabia experience higher levels of depression, stress and anxiety and stress during their education period, with a higher stress for female students compared to male students. There is an urgent need to introduce interventional programs and preventive strategies to overcome the long-term effects.