Assessment of Smear Layer Removal and Penetration Depth of Root Canal Irrigant Using Different Irrigation Activation Systems: A Comparative Study.

AIM: The aim of the current study was to evaluate the penetration depth and smear layer removal of root canal irrigant using various irrigation activation techniques. MATERIALS AND METHODS: In this investigation, sixty single-rooted premolars extracted for orthodontic purposes were chosen. Diamond burs were used to create an access cavity, and #10 K-file was used to determine the patency. About sixty samples were divided into the following three groups (20 samples in each group), group I: Irrigation with conventional needle, group II: Activation of EndoVac system, group III: Passive ultrasonic irrigation (PUI). The efficacy of the smear layer was assessed using a scanning electron microscopy at a ×2000 magnification. One-way ANOVA was used to record and analyze the data. All statistical analyses were performed with a significance level of p < 0.05. RESULTS: At coronal third, the maximum smear layer was removed in group II (1.26 ± 0.02) followed by group III (1.84 ± 0.16) and group I (2.89 ± 0.21). At middle third, smear layer removal was maximum in group I (1.18 ± 0.10) followed by group III (1.72 ± 0.09) and group I (2.66 ± 0.18). At apical third, the more smear layer was removed in group II (1.02 ± 0.01) followed by group III (1.58 ± 0.08) and group I (2.38 ± 0.06). There was a highly significant difference found between the three different irrigation systems at all three levels (p < 0.001). CONCLUSION: In conclusion, every irrigation device that was evaluated was successful in removing the smear layer from the root canal. However, the EndoVac system group removed a greater amount of smear layer compared with PUI and conventional needle group. CLINICAL SIGNIFICANCE: With the goal of promoting cleaning that is beyond the ability of mechanical devices, irrigation is a crucial part of root canal therapy. If an efficient irrigation delivery system is used, the irrigants can reach the working length (WL). This type of distribution system needs to provide a suitable amount of irrigants up to the WL, as well as have enough flow and be effective at debriding the entire canal system. How to cite this article: Pujari MD, Das M, Das A, et al. Assessment of Smear Layer Removal and Penetration Depth of Root Canal Irrigant Using Different Irrigation Activation Systems: A Comparative Study. J Contemp Dent Pract 2024;25(4):331-334.

The effect of cone beam computerized tomography voxel size and the presence of root filling on the assessment of middle mesial canals in mandibular molar teeth.

INTRODUCTION: The study aims to compare the detection of the middle mesial canal (MMC) in mandibular molar teeth using cone beam computed tomography (CBCT) with different voxel sizes when the mesiobuccal (MB) and mesiolingual (ML) canals have three distinct phases (unpreparation, preparation and obturation and the removal of the obturation and repreparation). METHODS: Two hundred forty-two extracted human mandibular molars were collected and kept in a physiological saline solution prior to use. 0.2-, 0.28- and 0.35-mm voxel sizes CBCT (n = 242) were performed in three phases (Ph): Ph1, no MB and ML canal preparation or obturation; Ph2, after MB and ML canals preparation and obturation; and Ph3, after the removal of the obturation of MB and ML canals and canals repreparation. Images were analyzed using OnDemand3D® software. After the CBCT acquisition in Ph3, all the samples were clarified to visualize the presence of the MMC directly. A blinded, previously calibrated examiner analyzed all the images. RESULTS: The MMC was detected in 15 of the 242 teeth after the clearing technique. The lowest MMC detection rate was observed at 0.35-mm voxel size regardless of the ML and MB canal condition, while the highest was observed at 0.2-mm voxel size (P < 0.05). There is no statistically significant difference between 0.2-mm and 0.28-mm voxel sizes (P > 0.05). In all voxel sizes, the highest rate of detectability of the MMC was seen in Phase 1, while the lowest was in Phase 2. CONCLUSIONS: It may be appropriate to take a 0.20-mm voxel size CBCT image, especially after the removal of root canal filling. CLINICAL RELEVANCE: An appropriate CBCT voxel size and the absence of root canal filling in the root canal system help to detect the missing MMC.

Expert consensus on difficulty assessment of endodontic therapy.

Endodontic diseases are a kind of chronic infectious oral disease. Common endodontic treatment concepts are based on the removal of inflamed or necrotic pulp tissue and the replacement by gutta-percha. However, it is very essential for endodontic treatment to debride the root canal system and prevent the root canal system from bacterial reinfection after root canal therapy (RCT). Recent research, encompassing bacterial etiology and advanced imaging techniques, contributes to our understanding of the root canal system's anatomy intricacies and the technique sensitivity of RCT. Success in RCT hinges on factors like patients, infection severity, root canal anatomy, and treatment techniques. Therefore, improving disease management is a key issue to combat endodontic diseases and cure periapical lesions. The clinical difficulty assessment system of RCT is established based on patient conditions, tooth conditions, root canal configuration, and root canal needing retreatment, and emphasizes pre-treatment risk assessment for optimal outcomes. The findings suggest that the presence of risk factors may correlate with the challenge of achieving the high standard required for RCT. These insights contribute not only to improve education but also aid practitioners in treatment planning and referral decision-making within the field of endodontics.

Assessment of Incidence, Management and Contributory Factors of Root Canal Instrument Separation in an Endodontics Post- Graduate Program: A Retrospective Clinical Study.

BACKGROUND: The successful outcome of nonsurgical root canal treatment (NS-RCT) is largely dependent on the technical quality of the procedure. OBJECTIVE: To investigate the incidence of separated instruments in endodontic postgraduate clinics between January 2018 and December 2021, and to determine the potential contributory factors that increase the risk of instrument separation. MATERIALS AND METHODS: A retrospective observational study was conducted in the Department of Endodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia. Data was collected to determine the incidence of separated instruments and their associated variables. Seven variables were analyzed separately: nonsurgical initial or retreatment case, tooth type, tooth arch, tooth location, canal type, root curvature, level of fracture, and file type. RESULTS: A total of 3150 cases were treated, of which 108 cases had separated instruments. The overall incidence of instrument separation was 3.4% while 53.7% of separated instruments occurred in the mandibular molars, followed by 42.6% in the maxillary molars. The highest frequency of instrument separation was recorded in the mesiobuccal canal (35.2%). The level of separation was found to be statistically significant in relation to the management (P < .001). CONCLUSION: Nickel-titanium instruments tend to separate more inside the root canal system than stainless steel instruments. However, under the limitation of this study, the incidence of instrument separation is still quite low, even with postgraduate endodontic residents with limited experience.

Assessment of the Effect of Different Irrigation Protocols on the Penetration of Irrigation Solution into Simulated Lateral Canals (In Vitro Study).

OBJECTIVE: To compare the effectiveness of lateral canal irrigation penetration by conventional needle, passive ultrasonic, sonic endo activator, and Erbium laser (2780nm). METHODS: A total of 40 palatal roots of human maxillary first molars were collected and instrumented at a working length of 12 mm by an X1-X4 rotary Protaper Next system (Dentsply, Maillefer, Ballaigues, Switzerland) using the crown-down technique. Artificial lateral canals were made at 2, 4, and 6 mm from the apex on mesial and distal sides using an ISO rotary reamer (Dentsply, Maillefer, Ballaigues, Switzerland; #10 for mesial, #08 for distal). The samples were then cleared using methyl salicylate. A solution of black ink and normal saline was used as an irrigant for the root canal. The percentages of the penetration of the ink into the lateral canals were measured using a stereomicroscope (Q-Scope, Arnhem, The Netherlands) with the aid of program Image J. The Tukey test is used to assess the significant difference between intragroup and intergroup comparisons of different thirds, and the T-test is used to assess the significant difference between every two groups and for the mesial and distal sides of each group. The level of significance was set at 0.05. RESULTS: Results showed that none of the activation techniques used resulted in complete lateral canal penetrations; however, on both sides at all thirds, the Erbium laser (2780 nm) achieved the highest results with a highly significant statistical difference (p=0.05) with all other groups, and the least penetration was in the conventional needle group. CONCLUSION: The size of the lateral canal is a restricting factor for all activation methods; the best results can be achieved by laser. Conventional needles cannot be used alone to disinfect complex canal anatomy; however, passive ultrasonic and sonic endo activator activations can produce comparable results.

Syringe irrigation in confluent canals: A sequential computational fluid dynamics assessment.

This study aims to assess the influence of root canal preparation, irrigation needle design and its placement depth in the irrigation flow of confluent canals during syringe irrigation. A mandibular molar presenting two confluent canals in its mesial root was sequentially prepared and scanned by micro-computed tomography after mechanical preparation up to ProTaper Next system sizes X2 (25/.06v), X3 (30/.07v) and X4 (40/.06v). In each of the root canal preparation models, a side-vented and an open-ended needle at 5, 3 and 2 mm from the working length were included, and irrigation flow was assessed by a validated computational fluid dynamics model. The results revealed that the irrigant flowed out of the confluent canals mainly through the canal that did not have the needle. Apical penetration and renewal of the irrigant were most efficiently achieved with the use of a 30G open-ended needle and a 30/.07v preparation.

Comparative assessment of cleaning efficacy of two exclusive paediatric rotary files in root canals of primary teeth: An in vitro study.

BACKGROUND: Paediatric rotary file systems have recently been developed for primary teeth use. AIM: To study the cleaning efficacies of two paediatric rotary endodontic files, the Prime PedoTM, and the Kedo-SG BlueTM against the standard H files. DESIGN: This in vitro study included 54 freshly extracted primary molars, which were randomised into three groups (n = 18 each) and were prepared using either Kedo-SG BlueTM, Prime PedoTM or hand H files after injecting methylene blue dye into the canals. Pre- and post-operative cone beam computerised tomography (CBCT) was performed to assess change in root canal volumes. Methylene blue dye removal from canals was assessed using stereomicroscopy, and canal cleanliness was examined by scanning electron microscopy (SEM). RESULTS: Both Prime PedoTM and Kedo-SG BlueTM files reduced significantly less dentine when compared with conventional hand filing with Prime PedoTM removing the least amount of dentine. No significant difference was found in median SEM scores among the groups in the cervical, middle and apical thirds of the roots. Stereomicroscopic assessment of root canal cleanliness using dye removal technique shows a statistically significant difference existing between Kedo-SG BlueTM and hand H files groups. CONCLUSION: Prime PedoTM removed the least amount of dentine. Kedo-SG BlueTM performed significantly better than conventional hand filing with H files when the root canal cleanliness was assessed.

Precision-milled simulated curved root canals in bovine dentine for the assessment of chemo-mechanical root canal preparation.

AIM: The aim was to develop a standardized curved root canal model in bovine dentine and to assess whether that natural substrate would behave differently from the resin in standard plastic training blocks when prepared chemo-mechanically. The impact of substrate microhardness on simulated canal transportation was considered. METHODOLOGY: High-precision computer numerical control (CNC) milling was used to recreate a simulated root canal from a resin training block (Endo Training Bloc J-Shape, size 15) in longitudinally sectioned, dis- and re-assembled bovine incisor roots. Optical overlays obtained from 10 resin blocks were used to identify an average canal and program the CNC milling apparatus accordingly. Resin and dentine microhardness were measured. Simulated root canals in resin training blocks and their bovine counterparts were then instrumented at 37°C using Reciproc R25 instruments (VDW) with water or 17% EDTA (n = 10). Open-access image processing software was used to superimpose and analyse pre- and postoperative images obtained with a digital microscope. Centering ratios were averaged to indicate canal transportation. The effects of substrate and irrigant on canal transportation were assessed by two-way anova. RESULTS: Superimposed images showed that resin blocks under investigation varied considerably in terms of simulated canal length and curvature, whilst the milled canals were highly similar. The microhardness of dentine was more than three times higher than that of the resin. Conversely, canal transportation was considerably greater in dentine compared to resin, and in dentine had a tendency to be increased by EDTA. There was a strong effect of substrate on canal transportation (p < .001), no overall effect of irrigant, and a marginally significant interaction between irrigant and substrate (p = .077). CONCLUSIONS: CNC milling allows to create standardized simulated curved root canals in bovine dentine. These models may be useful to test and compare materials and concepts of chemo-mechanical root canal instrumentation. Microhardness is a bulk feature that does not predict the response to chemo-mechanical instrumentation of a composite material such as dentine.

Assessment of the root surface temperature during the use of intracanal agitation systems: In vitro study.

This study aimed to evaluate the temperature changes that the different methods of agitation of irrigants promote on the external dental root surface. Nine extracted human lower premolars were standardized by cone-beam computed tomography and used. The root canal was instrumented with a Reciproc 40.06 file. Temperature measurement was performed using K-type thermocouple sensors attached to the middle, cervical, and apical thirds of the teeth. The teeth had their roots immersed in distilled water at 37ºC, which were distributed into 3 experimental groups according to the mechanical agitation methods to be studied. US Group (n=3), Irrisonic Ultrasonic Tip activated through ultrasound; EC Group (n=3), Easyclean Tip coupled to a contra-angle low-speed handpiece; XP Group (n=3), XP-endo Finisher file coupled to an endodontic electrical motor. Temperature measurements were performed simultaneously with agitation and irrigation of intracanal irrigants. Statistical analysis was performed using SPSS software with a significance level of 5%. For multiple comparisons, the Tukey test was used. The association between mechanical agitation methods and root third was statistically significant. Regarding the temperatures recorded on the external surface of the roots, the ultrasonic tip was significantly higher than the XP-endo Finisher file and the Easyclean tip, which did not differ from each other. Regarding the ultrasonic tip, the external temperature in the middle third (39.46ºC) of the root was significantly lower than in the cervical (40.41ºC) and apical third (40.53ºC). None of the agitation methods of irrigants studied presented heating above 47ºC, and their use is safe for periodontal tissues.

Assessment of clinical and radiographic efficiency of manual and pediatric rotary file systems in primary root canal preparation: a randomized controlled clinical trial.

INTRODUCTION: The success of primary teeth pulpectomy is strongly reliant on instrumentation techniques and their impact on obturation quality & postoperative pain. Recently, pediatric rotary file systems have been implemented. AIM: to compare two pediatric rotary file systems (Kedo-S-Square & Fanta AF™ Baby) with manual K-files concerning obturation quality, instrumentation time, and postoperative pain in root canal preparation of primary molars using cone beam computed tomography (CBCT). METHODS: A randomized clinical trial was conducted with the trial registration number (TRN: NCT05619796 and date of registration: (17/11/2022) on sixty primary lower 2nd molars in healthy children aged 4-7 years. Molars were assigned randomly to three groups (n = 20). Group-I and -II were prepared with Kedo-S-Square & Fanta AF™Baby rotary systems respectively while group-III was prepared with a manual K-file. Instrumentation time was recorded using a stopwatch. CBCT was used to assess obturation quality immediately & recorded as optimal, underfilled, or overfilled. Postoperative pain was evaluated at 6, 12, 24, 48 h-time intervals using a four-point pain intensity scale. Statistical analysis was performed for the collected data. RESULTS: Among the three groups, group-I revealed a greater number of optimally filled teeth (85%) & less instrumentation time (74.75 s) followed by group-II & manual-K file group (p < 0.05). The hand K-file group had significantly more postoperative pain than the two rotary groups (p < 0.05). CONCLUSION: the tested rotary file systems resulted in better obturation quality, less instrumentation time, and less postoperative pain compared to manual-K files during primary teeth pulpectomy.

Assessment of the root filling volume in C-shaped root canal on cone-beam CT and micro-CT in relation to nano-CT.

AIM: To assess the observed volume of filled C-shaped root canals from different CBCT and micro-CT having nano-CT as a reference. MATERIALS AND METHODS: Twelve extracted mandibular molars with C-shaped root canals were endodontically treated using Reciproc Blue R25 (VDW GMBH, Munich, Germany) in a reciprocating system and filled with gutta-percha (Dentsply Maillefer) and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). CBCT scans were performed using 3 units-3D Accuitomo 170 (J. Morita, Kyoto, Japan), ProMax 3D Max (Planmeca, Helsinki, Finland), and NewTom VGi EVO (Cefla QR, Verona, Italy)-at two resolution modes: standard and high. Micro-CT and nano-CT scans were also obtained. The volume of all filled C-shaped root canals was obtained using CTAn software (Bruker, Kontich, Belgium), and the blooming artifact, in relation to nano-CT volume, was calculated. The data were evaluated by the Bland-Altman plots and ANOVA two-way for repeated measures (α = 0.05). RESULTS: All CBCT units and micro-CT showed significantly larger observed volume of root canal filling when compared to nano-CT. The blooming artifact of root canal filling in standard resolution was significantly larger than that in high resolution (p < 0.05) in all CBCT units. CONCLUSIONS: Endodontic filling material with AH Plus sealer causes blooming artifacts in CBCT units and micro-CT. CLINICAL RELEVANCE: Considering the anatomical complexity of C-shaped root canals and the challenges associated with endodontic treatment, CBCT is frequently recommended for follow-up evaluations. However, the presence of endodontic filling material can result in blooming artifacts that may potentially impact the accurate diagnosis of endodontic complications.

Quantitative Assessment of Dimensional Evaluation and Artefacts from Filling Materials with CBCT Using Standard Phantom Roots.

OBJECTIVE: To investigate the accuracy of dimensional evaluation and representation of artefacts generated by different gutta-percha (GP) cones with or without sealer with CBCT using a reproducible, standardised phantom root methodology. METHODS: The reproducible artificial phantom roots with six root canal sizes from #25 to #50 and 0.04 taper were aligned according to the jaw curvature in a stone model for dimensional measurements. Each root was scanned while empty and filled with four types of filling materials. The specimens were scanned using the CS 9300 3D (Carestream Dental, Rochester, NY, USA) (at two different resolutions), 3D Accuitomo (J Morita, Kyoto, Japan) and NewTom VGi (Verona, Italy) CBCT systems. The hyperdense and hypodense axial slice artefacts from root canal sizes #40, #45 and #50 were recorded. RESULTS: Dimensions were significantly smaller and more accurate with CS 9300/0.09 mm voxel size than with other protocols. The hypodense band was found mostly in the CS 9300 3D system with 0.18 mm voxel size, especially in the buccal-lingual (95%) and coronal (64%) sections. The 3D Accuitomo CBCT system showed the lowest presence of the hypodense band. Areas of both light and dark artefacts were significantly larger in the coronal third than in the apical and middle thirds. CONCLUSION: Artefacts in the coronal locations and in buccal-lingual sections were more evident in the CS 9300 3D system with a 0.18-mm voxel size.

Shaping ability of WaveOne Gold and OneReci by using two apical sizes: a micro-computed tomographic assessment.

Backround: OneReci (MicroMega, Besançon, France) is a recently introduced single-file reciprocating system with scarce information revealed on its shaping ability. This study aimed to compare the shaping abilities of OneReci and a well-documented single-file reciprocating system WaveOne Gold (WOG; Dentsply Maillefer, Ballaigues, Switzerland) and evaluate the effect of increased apical enlargement on the preparation quality, using micro-computed tomography (micro-CT). Methods: After an initial micro-CT scanning, twenty mesial root canals of mandibular molars were anatomically matched. The canals were assigned to two experimental groups (n = 10), using OneReci or WOG in different canals of the same root. The glide paths were created, and root canals were prepared twice, using size 25 and 35 instruments of the systems, respectively. The specimens were scanned with micro-CT after each preparation. The increase in canal volume, amount of dentin removal, unprepared root canal surface, canal transportation, centering ratio and preparation times were assessed. The data were analysed with independent sample t-tests, variance analyses, Friedman and Mann-Whitney U tests. The significance level was set at 5%. Results: Each preparation increased the canal volume and dentin removal while decreasing the unprepared root surface. The difference between the systems became significant after preparation with size 35 instruments (p < 0.05). Regarding canal transportation and centering ratio, the difference was insignificant (p > 0.05). The first preparation step (glide path + size 25 instrument) was significantly faster in the OneReci group (p < 0.05). Conclusions: Preparation with size 25 instruments of the systems appeared to be safe with similar shaping performances. Larger apical preparation promoted significantly higher dentin removal, volume increase, and prepared surface area in WOG.

Effect of foraminal enlargement on microcrack formation and apical transportation: a nano-CT assessment.

The aim of this study was to evaluate the foraminal enlargement and its influence on microcrack formation and apical transportation in root canals with apical curvature. Eighteen maxillary lateral incisors with apical curvature were selected by using micro-CT images. Root canals were randomly divided in two groups (n = 9) according to root canal preparation using two working lengths: 1 mm short of the apical foramen (control group) and 1 mm beyond the apical foramen (foraminal enlargement). For both groups Reciproc Blue R40 was used for root canal instrumentation. Specimens were scanned by nano-CT (UniTOM HR) before and after root canal preparation. Percentage, length, and width of microcracks, and apical transportation were assessed. Kappa, chi-square and McNemar tests were used for qualitative analyses while paired and unpaired t-test were used for quantitative analyses (α = 0.05). For both groups, rather similar and low percentages of microcracks were observed before root canal preparation (P > 0.05). The foraminal enlargement promoted new microcracks, not observed in the control group. An increase in microcrack length was observed when the foraminal enlargement was performed (P < 0.05). Higher apical transportation was observed when foraminal enlargement was performed (P < 0.05). Foraminal enlargement using a heat-treated reciprocating file size 40 promoted microcracks and higher apical transportation than root canal preparation up to 1 mm short of apical foramen.

Assessment of Irrigant Agitation Devices in Simulated Closed and Open Root Canal Systems.

INTRODUCTION: The in vitro efficacy of irrigant activation devices has not been contrasted to their safety. This was attempted in this study using apically closed versus patent simulated root canal systems in epoxy resin models, with the latter featuring a simulated periapical lesion. METHODS: All 72 models had 2 joining canals connected by an isthmus, which was filled with dentin debris. The simulated periapical lesion was filled with colored gelatin in the 36 respective models. Canals were irrigated with 1.3% sodium hypochlorite. Samples were divided into 4 subgroups per system (n = 9): conventional irrigation, sonic low (EndoActivator; Dentsply Sirona, Charlotte, NC) and high frequency (EDDY; VDW, Munich, Germany), and ultrasonic agitation of the irrigant (always applying 3 cycles of 20 seconds). The total cleared surface areas (mm2) in the simulated isthmus and periapical lesion were compared between systems and devices using parametric tests (P < .05). RESULTS: The cleaning of the isthmus was more effective in the apically open compared with the closed systems and was also significantly influenced by the agitation method (P < .001). In the closed systems, EDDY and ultrasonic agitation achieved the significantly (P < .05) best cleaning of the isthmus. In the open systems, ultrasonic agitation showed the single best result (P < .05). EDDY caused by far the highest and ultrasonic agitation the lowest dissolution of the gelatin in the simulated periapical lesion. CONCLUSIONS: Under the conditions of this study, ultrasonic agitation of a previously administered sodium hypochlorite irrigant was more laterally targeted and thus safer and more effective than sonic agitation methods.

Thermal and volumetric assessment of endodontic filling techniques using infrared thermography and micro-CT.

PURPOSE: To assess root temperature during filling techniques and quantify the volume of endodontic filling materials using infrared thermography (IT) and micro-computed tomography (micro-CT). METHODS: Ninety premolars were divided into three groups: lateral condensation (LC), single cone (SC) and thermomechanical compaction (TMC). For thermal analysis, 45 teeth were assessed using a FLIR T650sc IT camera during filling techniques and 45 teeth were scanned using a Nikon micro-CT to assess gutta-percha, cement, and void volumes. Descriptive and inferential statistical analyses were performed (non-parametric Mann-Whitney test, Kruskal-Wallis test, and Friedman test with Tukey's bidirectional analysis of variance). RESULTS: TMC showed the highest temperature increase at 15 s after the procedure and a significant temperature decrease at 45 s after its completion. TMC showed the largest volume of gutta-percha and LC the highest void volume. CONCLUSION: The temperature increase generated by gutta-percha endodontic filling techniques is within acceptable limits. A greater volume of endodontic cement was observed for the SL and LC filling techniques.

An application framework of 3D assessment image registration accuracy and untouched surface area in canal instrumentation laboratory research with micro-computed tomography.

OBJECTIVES: The purpose of this study was to develop a customized framework for evaluating the registration accuracy of four registration techniques and measuring the untouched surface area of canal instrumentation by visually inspecting and calculating the overlapping area of the surfaces. METHODS: Twenty-one mandibular incisors were scanned by micro-computed tomography before and after instrumentation. Elastix registration, surface registration, manual registration, and DataViewer registration techniques were used to align the pre- and post-operative datasets. The customized MeVisLab framework was created to investigate the registration accuracy by visual inspection and calculating overlapping areas. The canal surfaces were imported into the same framework to measure the untouched surface area and the consistence test was validated. The correlation between registration accuracy and untouched surface area was analyzed. RESULTS: There is a statistically significant difference between manual registration and automatic registration (P < 0.05). There is no statistical difference between the two untouched surface measure methods (P > 0.05). The partial correlation coefficients for the untouched surface area and registration accuracy were 0.45 (P < 0.05). CONCLUSIONS: This application framework based on free customizable software, allows a new method to measure registration accuracy and untouched surface area in an efficient and sensitive way. The application of a precise registration method would improve the quality of micro-CT canal instrumentation studies. CLINICAL RELEVANCE: This study developed a customized framework based on free software for evaluating the registration accuracy of different registration techniques and measuring the untouched surface area of canal instrumentation could help researchers to improve the quality of micro-CT studies of canal instrumentation.

Assessment of the Effectiveness of Supplementary Methods for Residual Filling Material Removal Using Micro-computed Tomography: A Systematic Review and Meta-analysis of In Vitro Studies.

A systematic review and meta-analysis were conducted to evaluate the effectiveness of auxiliary methods in removing residual filling material (RFM). This systematic review has been registered with the International Prospective Register of Systematic Reviews (registration number CRD42020197482). A comprehensive literature search was conducted to identify relevant articles in electronic databases (PubMed, Embase, Cochrane) from January 2005 to March 2021. In vitro studies investigating or comparing at least one type of supplementary method or technique were included. A total of 26 studies were selected from the 239 records obtained after screening the databases. Ten of the included studies were suitable for meta-analysis. Strong evidence showed that ultrasonically activated irrigation (UAI) [SMD (95% CI): -0.52 (-0.88 to -0.16, P=0.266)] and XP-Endo Finisher R (XPR) [SMD (95% CI): -0.55 (-0.89 to -0.20, P=0.136)) contributed significantly to increase the removal procedure, and XPR has no significant superiority over UAI [SMD (95% CI): 0.36 (-0.12 to 0.84, P=0.994)]. Strong evidence was found to support the increased cleaning efficiency of the supplementary use of the Gentle Wave system, laser irradiation, XP Endo Finisher, and self-adjusting file. In contrast, conflicting evidence was found to support the use of sonic to improve the removal of RFM, and limited evidence was found to support the efficiency of Tornado Brush. Under in vitro conditions, UAI and XPR increase the removal of RFM from the root canal system during retreatment procedures.

Radiographic assessment of endodontic mishaps in an undergraduate student clinic: a 2-year retrospective study.

Objectives: The aim of this study was to compare the occurrence of instrumentation and obturation related endodontic procedural mishaps following the use of either, stainless steel hand or engine-driven rotary instrumentation techniques. Methods: From a computerized hospital database, a total of 730 dental patient records who had received endodontic treatment by undergraduate dental students between August 2018 to September 2020 were retrieved. The inclusion criteria were primary (non-surgical) endodontic treatment on permanent teeth with complete radiographic records. Following record screening, a final sample of n = 475 dental records were included. Radiographic records were evaluated for both instrumentation and obturation related mishaps. The data was analysed using multiple logistic regression analysis (α = 0.05). Results: Engine-driven rotary instrumentation resulted in a significant decrease in the overall occurrence of instrumentation related endodontic mishaps by 40% compared to hand instrumentation (Odds Ratio = 0.59 [0.36-0.97], p = 0.04). In particular, rotary instrumentation decreased ledge formation, perforation and obturation related mishaps, with minimal effect on the limitation of zipping. Conclusion: The use of rotary instrumentation techniques may reduce the incidence of instrumentation and obturation endodontic mishaps in the undergraduate dental clinic.

Economic analysis of the different endodontic instrumentation techniques used in the Unified Health System.

BACKGROUND: To assess the financial impact of incorporating a new (reciprocal) technology into endodontic treatments in the public health system (SUS). METHODS: This was a economic evaluation study (comparing the 3 different endodontic instrumentation techniques-manual, rotary and reciprocating), allocative efficiency analysis to optimize existing resources in the SUS, and financial contribution impact analysis of incorporation of a new technology. Thirty-one (31) 12 years-old volunteers were evaluated. RESULTS: The incremental cost-effectiveness ratio (ICER) was calculated at R$1.34/min, - R$0.60/min and BRL 0.10/min for the single-rooted, bi-rooted and tri-rooted teeth, respectively, when the rotary technique was compared with the manual type. In turn, the ICER was R$ 21.04/min, - R$ 0.73/min and - R$ 2.81/min for the 3 types of teeth, respectively, when the reciprocating technique was compared with the manual type. The incremental financial impact of replacing manual endodontic with rotary endodontic treatments would be - R$ 2060963.66 in the case of single-rooted teeth, but the number of treatments would also be reduced (- 19,379). In the case of two-rooted teeth, the incremental financial impact would be BRL 34921540.62 with the possibility of performing an additional 204,110 treatments. In turn, BRL 11523561.50 represented the incremental financial impact for teeth with 3 or more roots and with an increase of 72,545 procedures. When we analyzed the incremental financial impact of replacing manual endodontic with reciprocating endodontic treatments, it would be - R$ 730227.80 in the case of single-rooted teeth, allowing for an additional 2538 treatments. In turn, R$ 21674853.00 represented the incremental financial impact for bi-radicular teeth, with an increase of 121,700 procedures. In the case of two-rooted teeth, the incremental financial impact would be BRL 13591742.90 with the possibility of performing an additional 40,670 treatments. CONCLUSIONS: The reciprocating technique could improve access to endodontic treatment in the SUS as it allowed a simultaneous reduction in clinical time and associated costs. However, the higher number of endodontic treatments performed would have a financial impact.