Effectiveness of continuous chelation irrigation protocol in endodontics: a scoping review of laboratory studies.

This scoping review aimed to synthesize and explore the current boundaries and limitations of laboratory research on the effectiveness of continuous chelation irrigation protocol in endodontics. This scoping review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews. Literature search was conducted on Pubmed and Scopus to identify all laboratory studies evaluating smear layer and hard-tissue debris removal or, antimicrobial efficacy, or dentine erosion induced by continuous chelation. Two independent reviewers performed the all review steps and the relevant items were recorded. Seventy-seven potentially relevant studies were identified. Finally, 23 laboratory studies met the eligibility criteria for qualitative synthesis. Seven studies focused on the smear layer/debris removal outcome, 10 on antimicrobial activity, and 10 on dentine erosion. In general, the continuous chelation protocol was equally or more effective in the cleanliness of root canals and antimicrobial activity compared with traditional sequential protocol. In addition, etidronate solutions seemed to be milder chelating agents compared to those with EDTA, thus resulting in reduced or no dentine erosion and roughness modification. Yet, the methodological differences among the included studies limit the results' generalizability. The continuous chelation seems to be equally or more effective in all investigated outcomes when compared with the traditional sequential protocol. The methodological variability among the studies and shortcomings in the methods employed limit the generalizability and clinical relevance of the results. Standardized laboratory conditions combined with reliable three-dimensional investigation approaches are necessary to obtain clinically informative findings.

Effectiveness of intentional replantation in managing teeth with apical periodontitis: A systematic review.

BACKGROUND: Intentional replantation (IR) to treat disease of endodontic origin remains controversial. While IR has been advocated by some clinicians as another valid treatment option, others consider it as a treatment procedure of last resort. OBJECTIVE: To systematically review and critically evaluate the effectiveness of IR compared with nonsurgical root canal treatment/retreatment or apical surgery in terms of clinical and patient-related outcomes in managing permanent teeth with apical periodontitis (AP). METHODS: A literature search of five databases (PubMed, Embase, Scopus, Web of Science and Cochrane Central register of Controlled Trials), and the grey literature (Networked Digital Library of Theses and Dissertations, Open Access Theses and Dissertations, DART-Europe E-theses Portal, British Library E-Theses Online Service), from inception to November 2021, was conducted. Randomised clinical trials, comparative clinical trials (CCTs), nonrandomised, retrospective, and prospective comparative cohort and case-control two arm studies which evaluated clinical and/or patient-related outcomes of permanent teeth with AP treated with IR compared with nonsurgical root canal treatment/retreatment or apical surgery were identified. The quality of the studies was appraised using the Cochrane risk of bias tool for randomized trials (RoB 2.0), the Robins-I for nonrandomized controlled clinical trials and the Newcastle-Ottawa scale for observational studies. Two independent reviewers were involved in the literature selection, performed the data extraction and the appraisal of the studies identified; disagreements were resolved in conjunction with a third reviewer. RESULTS: No comparative study was identified from the literature search. Four longitudinal studies (one prospective and three retrospective) were identified during the screening of titles and abstracts but were excluded after reading the full text, because only IR was evaluated (single arm studies). DISCUSSION: The available evidence on IR is mainly based on observational studies, which reported high overall mid- to long-term survival, and low complication rates. The results suggest that IR may represent an alternative treatment procedure to solve problems of endodontic origin. However, in the absence of high-quality evidence from CCTs, clinical decision-making should be on a case-by-case basis and in accordance with the clinician's experience and the patient's preference. CONCLUSION: Clinical studies showed that IR may be a treatment modality to manage problems of endodontic origin. However, clinical trials comparing the effectiveness of IR with nonsurgical root canal treatment/retreatment or apical surgery are still required given the paucity of evidence.

Instrumentation kinematics does not affect bacterial reduction, post-operative pain, and flare-ups: A randomized clinical trial.

AIM: This randomized clinical trial aimed to assess the effect of instrumentation kinematics (reciprocation or continuous rotation) on bacterial reduction, post-operative pain, and incidence of flare-ups after root canal treatment of single-rooted mandibular premolars with asymptomatic apical periodontitis. METHODOLOGY: Sixty-six patients were included in this prospective, parallel, randomized clinical trial. Patients were randomly allocated into two groups (N = 33) according to the kinematics of the shaping instrument: WaveOne Gold (WO) used in reciprocation or One Shape (OS) used in continuous rotation. Under complete asepsis, bacterial samples were taken before (S1) and after (S2) a standard cleaning and shaping protocol. Evaluation of bacterial reduction was done by both culture technique and quantitative real-time polymerase chain reaction (qPCR) analysis. Post-operative pain was evaluated using the visual analogue scale (VAS) after 24, 48, and 72 h following treatment, while flare-ups were recorded as a binary outcome (Yes/No). Independent and paired t-tests were used for inter- and intra-group comparisons for bacterial count data, respectively. For post-operative pain score, inter-group comparisons were analyzed using the Mann-Whitney U-test while intra-group comparisons were analyzed using Friedman test followed by pairwise comparisons utilizing the Wilcoxon signed rank test with Bonferroni correction. The significance level was set at p ≤ .05 within all tests. RESULTS: All the allocated participants received the intervention and were analysed. The comparison between culture and qPCR methods showed that qPCR analysis demonstrated significantly higher pre-instrumentation baseline bacterial count (p < .05). The percentage of bacterial reduction, detected by either method, significantly decreased after instrumentation using either rotation or reciprocation kinematics (p < .05). However, the difference between the WOG or OS files was statistically non-significant (p > .05). The intra-group comparisons showed a significant reduction in post-operative pain with time (p < .05) for both groups. However, the inter-group comparison demonstrated that the difference in post-operative pain after the use of either WOG or OS was statistically non-significant (p > .05). The incidence of flare-ups between both groups was also not-significant (p = 1). CONCLUSIONS: Shaping kinematics, either rotation or reciprocation motions, had no impact on bacterial reduction and the incidence of post-operative pain and flare-ups after root canal preparation of single-rooted premolars with asymptomatic apical periodontitis.

Present status and future directions: Surgical extrusion, intentional replantation and tooth autotransplantation.

Surgical extrusion, intentional replantation and tooth autotransplantation procedures are important treatment options that clinicians may consider performing in their day-to-day clinical practice. Despite compromised teeth are generally considered for extraction, clinicians must be aware that these cases could be suitable for management by these alternative predictable treatment options. Surgical extrusion, intentional replantation or tooth autotransplantation have similar treatment protocols which includes atraumatic tooth extraction, visualisation of the root portion and replantation. Surgical extrusion is defined as the 'procedure in which the remaining tooth structure is repositioned at a more coronal/supragingival position in the same socket in which the tooth was located originally'. Intentional replantation is defined as the 'deliberate extraction of a tooth and after evaluation of root surfaces, endodontic manipulation and repair, placement of the tooth back into its original position'. Tooth autotransplantation is defined as the 'transplantation of an unerupted or erupted tooth in the same individual, from one site to another extraction site or a new surgically prepared socket'. The same team previously published a narrative review (International Endodontic Journal. 2020, 53, 1636) and European Society of Endodontology position statement (International Endodontic Journal. 2020, 54, 655) on this topic in International Endodontic Journal. The aim of the current updated review was to provide the reader a complete overview and background on these procedures, to established clear clinical protocols and step-by-step for technically perform these therapies in their clinical practice and to establish future directions on the topics. The clinicians must periodically update their knowledge about these three procedures to achieve success.

Influence of environmental temperature, heat-treatment and design on the cyclic fatigue resistance of three generations of a single-file nickel-titanium rotary instrument.

The aim of the present study was to evaluate the effect of environmental temperature, heat-treatment*** and design on the cyclic fatigue resistance of OneShape (OS), OneShape new generation (OSNG) and One Curve (OC) NiTi rotary single-file instruments. Cyclic fatigue testing of NiTi instruments was performed in an artificial canal with a 5-mm radius of curvature and a 60° angle of curvature located 5 mm from the tip of the instrument. During the experiment 3 different temperatures were used in a thermostatic bath with electronic and infrared controls: 0°, 20° and 35 °C. Sixty OneShape, 60 OneShape new generation and 60 One Curve instruments were rotated in the artificial canal until fracture occurred and the number of cycles to fracture (NCF) and the length of the fractured fragment (FL) was recorded. Data were analyzed by one-way ANOVA test at the 5% significance level. Fatigue resistance was significantly higher as the environmental temperature decreased, with differences ranging from 61 to 791%. OC instruments were significantly more resistant to cyclic fatigue than OS and OSNG instruments at all the temperatures tested (P < 0.05). There was no significant difference with respect to the length of the fractured file fragments for all the instruments tested at all the temperatures tested (P > 0.05). Within the limitation of the present study, fatigue resistance of the files was significantly increased when the environmental temperature decreased. OC instruments were significantly more resistant to cyclic fatigue than OS and OSNG instruments at all the temperatures tested.

Cyclic fatigue resistances of Hyflex EDM, WaveOne gold, Reciproc blue and 2shape NiTi rotary files in different artificial canals.

The aim of the present study was to compare the cyclic fatigue resistances of HyFlex EDM (HEDM), WaveOne Gold (WOG), Reciproc Blue (RB), and 2Shape (TS) NiTi systems having different metallurgic properties. HEDM, WOG, RB, and TS instruments were rotated in artificial canals which were made of stainless steel with an inner diameter of 1.5 mm, 45°, and 90° angles of curvatures and a radius of curvature of 5 mm until fracture occurred, and the time to fracture (TTF) was recorded in seconds. Also, number of cycles to fracture was calculated (NCF). Data were statistically analyzed using Kruskal-Wallis and t test. The statistical significance level was set at P < 0.05. When comparing the TTF of all the instruments tested in the artificial canal with 45° curvature, RB had statistically the highest cyclic fatigue resistance followed by HEDM and TS (P < 0.05), while the WOG showed the lowest cyclic fatigue resistance (P < 0.05). In artificial canal with 90° curvature, RB showed a significantly higher cyclic fatigue resistance than the other tested files (P < 0.05), while there was no significant difference among the TS, WOG and HEDM groups (P > 0.05). When the NCF values were taken into consideration, HEDM reported a significantly higher cyclic fatigue resistance than TS in both canal curvatures analyzed (P < 0.05). Within the limitations of the present study, RB NiTi files showed statistically higher cyclic fatigue resistance in artificial canals with 45° and 90° than the other NiTi files tested.

Cutting efficiency of nickel-titanium rotary and reciprocating instruments after prolonged use.

The aim of the present study was to compare the cutting efficiency of Twisted File instruments used in continuous rotation or TF Adaptive motion and evaluate if prolonged use significantly affected their cutting ability. 20 new NiTi instruments were used in the present study (TF tip size 35, 0.06 taper; Sybron-Endo, Orange, CA, USA), divided into 2 subgroups of 10 instruments each, depending on which movement was selected on the endodontic motor. Group 1: TF instruments were activated using the program TF continuous rotation at 500 rpm and torque set at 2 N; Group 2: TF instruments were activated using the reciprocating TF Adaptive motion. Cutting efficiency was tested in a device developed to test the cutting ability of endodontic instruments. Each instrument cut 10 plastic blocks (10 uses) and the length of the surface cut in a plastic block after 1 min was measured in a computerized program with a precision of 0.1 mm. Maximum penetration depth was calculated after 1 use and after 10 uses, and mean and standard deviation (SD) of each group was calculated. Data were statistically analyzed with a one-way ANOVA test (P < 0.05). TF instruments used in continuous rotation (Group 1) cut a mean depth of 10.4 mm (SD = 0.6 mm) after the first use and 10.1 mm (SD 1.1 mm) after 10 uses, while TF instruments used with the Adaptive motion cut a mean depth of 9.9 mm (SD = 0.7 mm) after the first use and 9.6 mm (SD = 0.9 mm) after 10 uses. There was no statistically significant difference between the two groups investigated (P > 0.05) nor between instruments after 1 or 10 uses. In conclusion, the TFA motion showed a lateral cutting ability similar to continuous rotation and all tested instruments exhibited the same cutting ability after prolonged use.

Cyclic fatigue of instruments for endodontic glide path.

Endodontic glide path is the creation of a smooth patency from canal orifice to apex, which can be performed manually or with small tapered NiTi rotary instruments. The use of stainless steel (SS) hand K-files inserted in a reciprocating handpiece can be a possible alternative to create a mechanical glide path. The aim of this study was to compare the cyclic fatigue resistance between SS K-files used in a reciprocating motion and NiTi rotary instruments in artificial curved canals. Ten SS size 15 K-files used with the M4 handpiece (SybronEndo, Glendora, CA, USA) and ten PathFiles (Maillefer-Dentsply, Ballaigues, CH, Switzerland) NiTi rotary instruments size 16, 0.02 taper were tested for resistance to cyclic fatigue. The time to fracture inside an artificial curved canal was recorded for each instrument. Data were analyzed by one-way ANOVA and Tukey HSD test. Mean time (and SD) to failure was 464 s (±40.4) for the Group PF (NiTi rotary PathFile), and 1049 s (±24.8) for the Group M4 (SS K-files reciprocating) with a statistically significant difference between the two groups (p = 0.033). The SS 15 K-files used with the M4 handpiece showed a significant greater resistance to cyclic fatigue when compared to the NiTi rotary PathFiles. Therefore, the use of small size SS files in a reciprocating motion might be a rational choice for the creation of a mechanical endodontic glide path in curved root canals.

A new device to test cutting efficiency of mechanical endodontic instruments.

BACKGROUND: The purpose of the present study was to introduce a new device specifically designed to evaluate the cutting efficiency of mechanically driven endodontic instruments. MATERIAL AND METHODS: Twenty new Reciproc R25 (VDW, Munich, Germany) files were used to be investigated in the new device developed to test the cutting ability of endodontic instruments. The device consists of a main frame to which a mobile plastic support for the hand-piece is connected and a stainless-steel block containing a Plexiglas block against which the cutting efficiency of the instruments was tested. The length of the block cut in 1 minute was measured in a computerized program with a precision of 0.1mm. The instruments were activated by using a torque-controlled motor (Silver Reciproc; VDW, Munich, Germany) in a reciprocating movement by the "Reciproc ALL" program (Group 1) and in counter-clockwise rotation at 300 rpm (Group 2). Mean and standard deviations of each group were calculated and data were statistically analyzed with a one-way ANOVA test (P<0.05). RESULTS: Reciproc in reciprocation (Group 1) mean cut in the Plexiglas block was 8.6 mm (SD=0.6 mm), while Reciproc in rotation mean cut was 8.9 mm (SD=0.7 mm). There was no statistically significant difference between the 2 groups investigated (P>0.05). CONCLUSIONS: The cutting testing device evaluated in the present study was reliable and easy to use and may be effectively used to test cutting efficiency of both rotary and reciprocating mechanical endodontic instruments.

Fatigue resistance of rotary instruments manufactured using different nickel-titanium alloys: a comparative study.

The aim of this study was to investigate whether cyclic fatigue resistance is increased for Controlled Memory (CM) Nickel-Titanium (NiTi) instruments, compared to instruments produced using traditional NiTi and instruments produced using M-Wire alloy. Two groups of NiTi endodontic instruments consisting of identical instrument sizes (constant 0.06 taper and 0.25 tip diameter and constant 0.04 taper and 0.40 tip diameter) were tested: group A compared Hyflex™ CM, Vortex ™ and ProFile ™ size 25 and 0.06 taper and group B compared Hyflex™ CM, Vortex™ and ProFile™ size 40 and 0.04 taper. 10 files from each different subgroup were tested for cyclic fatigue resistance. Mean and standard deviations of the Number of Cycles to Failure (NCF) were calculated for each group and data were statistically analysed (p < 0.05). Hyflex™ CM instruments, size 25 and 0.06 taper, and size 40 and 0.04 taper, showed a significant increase in the mean number of cycles to failure when compared with size 25 and 0.06 taper Vortex™ and ProFile™. No statistically significant difference (p > 0.05) was noted between Vortex™ and ProFile™ in the tested sizes. The new manufacturing process involving memory shape heat treatment produced new NiTi rotary files (Hyflex™ CM) significantly more resistant to fatigue than instruments produced with other proprietary methods of treatment (Vortex™) and with the traditional NiTi grinding process (ProFile™).

In Vitro Evaluation of Smear Layer and Debris Removal and Antimicrobial Activity of Different Irrigating Solutions.

OBJECTIVE: The aim of this in vitro study was to compare the smear layer and debris removal and antimicrobial activity of two dual-action irrigating solutions for continuous chelation (Triton; Brasseler, Savannah, USA and Dual Rinse HEDP; Medcem GmbH, Weinfelden, Switzerland) with a dual step irrigation protocol with sodium hypochlorite (NaOCl) followed by ethylenediaminetetraacetic acid (EDTA). METHODS: Thirty single-rooted single-canal teeth were divided into three groups (n=10) and irrigated with Triton, Dual Rinse HEDP mixed with 6% NaOCl and 6% NaOCl/17% EDTA. The teeth were observed under a scanning electron microscope (SEM) to assess the canal wall cleanliness. In addition, 80 dentine discs were contaminated with Candida albicans and 80 discs with Enterococcus faecalis and irrigated with Triton, Dual Rinse HEDP mixed with 6% NaOCl and 6% NaOCl/17% EDTA or not treated (n=20). Fifteen discs were used to evaluate colony-forming units, while 5 discs were analysed by SEM. Data were analysed using the Shapiro- Wilk, Kruskal-Wallis and One-Way ANOVA tests. RESULTS: Triton was statistically more effective than Dual Rinse HEDP and NaOCl/EDTA in removing debris (p<0.05), except with NaOCl/EDTA in the coronal third. Triton was more effective than Dual Rinse HEDP in removing the smear layer from the apical and middle thirds (p<0.05). All the irrigation protocols significantly re- duced the number of E. faecalis. The Triton group showed the lowest number of remaining C. albicans (p<0.05). CONCLUSION: Triton was the most effective irrigation solution in removing debris and as effective as NaOCl/ EDTA in removing the smear layer. Triton showed the highest efficacy against C. albicans. New irrigating solutions that provide continuous chelation may provide an alternative to current irrigation protocols.

The micro-shear bond strength of new endodontic tricalcium silicate-based putty: An in vitro study.

This study aimed to compare in vitro micro-shear bond strength (µSBS) of three different endodontic tricalcium silicate-based materials in contact with a bulk-fill resin-based composite. Thirty cylindrical resin blocks with a hole in the centre (2 mm in depth and 4 mm in diameter) were manufactured with a 3D printer and divided into three groups (n = 10), depending on the calcium silicate cement used: light curing TheraCal LC (Bisco, Schaumburg, IL, USA), liquid-powder NeoMTA 2 (NuSmile Avalon Biomed, Bradenton, FL, USA) and putty NeoPutty (NuSmile, Houston, TX, USA). Each sample was stored for 24 h at 37°C and 100% humidity. Then, after adhesive placement, the restorative material Filtek bulk-fill (3 M ESPE, St. Paul, MN, USA) was placed over the capping material using cylindrical plastic capsules (2 mm height and 2 mm) and polymerised for 20 s. Specimens were then tested in a universal testing machine for the compression load resulting in the µSBS. The data were compared with the one-way ANOVA (Welch) and the Tamhane test. The mean value was significantly higher in the TheraCal LC group than in the other two groups (p < 0.05). There was no significant difference between NeoMTA 2 and NeoPutty groups (p > 0.05). The majority of failure modes for all groups were cohesive within biomaterial. Using TheraCal LC in the pulp capping procedure can result in higher bond strength values to the tested bulk-fill resin-based composite than NeoMTA 2 and NeoPutty.

Micro-shear bond strength of different calcium silicate materials to bulk-fill composite.

Introduction: This study aimed to compare the micro-shear bond strength (µSBS) performances of two resin-based calcium silicate-based cement (CSC) (TheraCal PT and TheraCal LC), Biodentine, and two modified-MTA CSC materials (NeoMTA 2 and BioMTA+) to bulk-fill restorative material. Materials and Methods: Fifty 3D printed cylindrical resin blocks with a central hole were used (2 mm in depth and 4 mm in diameter). CSCs were placed in the holes (per each group n = 10) and incubated for 24 h. Cylindrical polyethylene molds (2 mm in height and diameter) were used to place the bulk-fill restorative materials on the CSCs and polymerize for 20 s. Then, all specimens were incubated for 24 h at 37 °C at a humidity of 100%. Specimen's µSBSs were determined with a universal testing machine. Data were analyzed with one-way ANOVA (Welch) and Tamhane test. Results: Statistically higher µSBS was found for TheraCal PT (29.91 ± 6.13 MPa) (p < 0.05) respect to all the other materials tested. TheraCal LC (20.23 ± 6.32 MPa) (p > 0.05) reported higher µSBS than NeoMTA 2 (11.49 ± 5.78 MPa) and BioMTA+ (6.45 ± 1.89 MPa) (p < 0.05). There was no statistical difference among TheraCal LC, NeoMTA 2 and Biodentine (15.23 ± 7.37 MPa) and between NeoMTA 2 and BioMTA+ (p > 0.05). Conclusion: Choosing TheraCal PT as the pulp capping material may increase the adhesion and µSBS to the bulk-fill composite superstructure and sealing ability.

The Biomechanical Behaviour and life span of a Three-Rooted Maxillary First Premolar with Different Access Cavity Designs: A Finite Element Analysis.

OBJECTIVE: The present study aimed to evaluate the influence of different access cavity designs on the biomechanical behaviour of a three-rooted maxillary first premolar using finite element analysis (FEA). METHODS: Three experimental FEA models were generated: the intact tooth (IT) model, the traditional access cavity (TAC) model, and the conservative access cavity (CAC) model. In both TAC and CAC models, root canals preparation was simulated as follows: the mesiobuccal and distobuccal canals with a final tip size of 30 and taper of 0.04 and the palatal canal with a final tip size of 35 and taper of 0.04. Cyclic loading of 50 N was simulated on the occlusal surface of the three models. The number of cycles until failure (NCF), the location of failure, stress distribution patterns, maximum von Mises (VM), and maximum principal stress (MPS) were all evaluated and compared. RESULTS: Both types of access cavity preparation caused a reduction in the lifelog of the tooth; when compared to the IT model the TAC model had a lifelog of 94.82% while the CAC model had a lifelog of 95.80%. The maximum VM stresses value was registered on the occlusal surface of the TAC model (7 MPa), while the minimum was on the occlusal surface of the IT (6.2 MPa). MPS analysis showed that the highest stress value was recorded on the occlusal surface of the CAC model (7.71 MPa), while the least was recorded on the occlusal surface of the TAC model (3.77 MPa). Radicular stresses were always of minimal value regardless the model. CONCLUSION: The relation between the access cavity margins and the functional load points is a deciding factor that influences the biomechanical behaviour and fatigue life of endodontically treated teeth. (EEJ-2023-01-03).

Evaluation of Dentine Structure Loss after Separated File Retrieval by Three Different Techniques: An Ex-vivo Study.

OBJECTIVE: To evaluate the success rate of retrieving separated instrument, the root canal volume changes using cone-beam computed tomography and the retrieval time using Ruddle's technique, Terauchi file retrieval kit (TFRK) and Endo Rescue kit. METHODS: Sixty human mandibular first molars were selected, and a 4-mm portion of #25/.04 rotary files were separated in the middle third of moderately curved mesio-buccal canals. Teeth were randomly assigned into three groups (n=20): R group, in which separated files were retrieved according to Ruddle's technique; T group, in which separated files were retrieved using TFRK and E group, in which separated files were retrieved using Endo Rescue kit. Values were analyzed using IBM SPSS. Results presented as mean+-standard deviation and 95% confidence interval for the root canal volume and time and frequency (%) for success rate. Comparisons of differences in time, canal volume and success rate between groups were assessed. RESULTS: Retrieval was successful in R and T groups (70% and 80% respectively) without any significant difference between them (p=0.715), while E group hadn't any successful samples (0.0%) with significant difference compared to R and T groups (p<0.001, p<0.001). E group showed the highest increase in canal volume followed by R group, while T group exhibited the lowest increase in canal volume. There was no significant difference in the mean retrieval time between R and T groups (p=0.815). CONCLUSION: TFRK provides a more conservative way for retrieval of separated instrument from the middle third of moderately curved canals. (EEJ-2023-01-01).

Efficacy of different irrigant activation devices in removing dentin debris from an artificial isthmus connecting curved canals.

The aim of this study was to evaluate the debridement efficacy of sonic irrigation (EDDY; VDW, Munich, Germany and EndoActivator; Dentsply-Sirona, Ballaigues, Switzerland) and ultrasonically activated irrigation (Irrisafe; Satelec Acteon, Merignac, France) in a simulated canal isthmus connecting curved canals. Transparent resin blocks were produced containing two curved canals connected with an isthmus. The isthmus was then filled with dentin debris. Three irrigant activation cycles were performed and the amount of remaining debris was compared analysing pictures taken after each activation cycle. Data were statistically analysed using one-way ANOVA and post hoc Tukey tests at a significance level of p < 0.05. EDDY showed greater efficiency in removing dentin debris from the simulated isthmus than the other techniques tested. An increase in the activation time enhanced the efficiency of both EDDY and ultrasonically activated irrigation in debris removal.

Effect of Continuous Chelation Irrigation Using DualRinse HEDP+3% NaOCl with or without High-power Sonic Activation on Debris and Smear Layer Removal.

OBJECTIVE: This study aimed to assess the effect of sodium hypochlorite (NaOCl) combined with a novel chelating agent DualRinse HEDP (Medcem GmbH, Weinfelden, Switzerland), a product consisting of 0.9 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) powder, with or without high-power sonic activation on debris and smear layer removal. METHODS: Seventy-five mandibular premolars were divided into 5 groups (n=15) and treated with different irrigation protocols: group 1 (D3N), DualRinse HEDP+3% NaOCl without activation; group 2 (D3NA), DualRinse HEDP+3% NaOCl with activation (EDDY, VDW, Munich, Germany) during the final irrigation; group 3 (3NE), 3% NaOCl+17% Ethylenediaminetetracetic acid (EDTA)+3% NaOCl without activation; group 4 (3NEA), 3% NaOCl+17% EDTA+3% NaOCl with activation during the final irrigation; group 5 (NC), negative control group, 0.9% saline. Samples were analysed by scanning electron microscopy (SEM) to evaluate residual debris and smear layer at 3 levels of the root canal: coronal, middle, and apical. Statistical analysis was performed with a level of significance set at p<0.05. The normality distribution of scores within each group was assessed using Kolmogorov-Smirnov and Shapiro-Wilk tests. A Kruskal-Wallis test followed by multiple comparison tests was used to compare scores among the 5 groups on the apical, middle, and coronal levels of the root canal. A Friedman test followed by multiple comparison tests was used to compare scores within the apical, middle, and coronal levels for each treatment group. RESULTS: Debris score was significantly the lowest for D3NA, followed by D3N, 3NEA and 3NE at all root levels (p<0.05). The smear layer score was significantly the lowest for D3NA, followed by D3N, 3NEA and 3NE only at the apical level, while no significant difference was found in the middle and coronal levels between the groups (p<0.05). DualRinse HEDP resulted in less debris and smear layer compared to the classic approach of NaOCl without activation. Implementing sonic activation further improved debris and smear layer removal. CONCLUSION: DualRinse HEDP+3% NaOCl improved debris removal at all levels and smear layer elimination at the apical level of the root canal. These results were further enhanced when adding high-power sonic activation. (EEJ-2022-09-116).

Cone-Beam Computed Tomography Assessment of Prevalence of Procedural Errors in Maxillary Posterior Teeth.

A range of procedural errors can occur when performing endodontic treatment on posterior teeth. These errors may decrease the success rate in endodontic practice. This study assessed the prevalence of procedural errors and the quality of endodontic treatments in maxillary molars and premolars using cone-beam computed tomography (CBCT). CBCT scans from two private radiology centers were assessed retrospectively to ensure the same calculated sample size of 327 teeth for each of the four maxillary posterior tooth types (a total of 1,308 endodontically treated teeth). Image sets were evaluated for procedural errors categorized as follows: obturation length (overfilling or underfilling by >2 mm short of the root apex), missed canals, perforations, strip perforations (with extrusion of material into the furcation area), separated instruments in the root canal space, and root fracture. Data were analyzed with SPSS version 20 (SPSS Inc., Chicago, IL, USA), and frequency data was assessed using the Monte Carlo test at the 0.05 level of significance. The procedural errors most commonly reported in the present study were from most frequent to least frequent: underfilled canals (50.0%), missed canals (27.5%), overfilled canals (12.5%), apical perforations (5.0%), separated instruments (3.1%), and root fractures (1.9%). No strip perforations (with extrusion of material into the furcation area) were seen in the study (0%). Underfilled and missed root canals were the most frequent procedural errors identified in the present study. These findings underline the importance of more consideration of critical working length management during all stages of root canal treatment, greater awareness of root canal anatomy, and the use of imaging and diagnostic devices that enhance the ability to identify and treat root canals both safely and effectively.

Stronger than Ever: Multifilament Fiberglass Posts Boost Maxillary Premolar Fracture Resistance.

This paper investigates the influence of cavity configuration and post-endodontic restoration on the fracture resistance, failure mode and stress distribution of premolars by using a method of fracture failure test and finite elements analysis (FEA) coupled to Weibull analysis (WA). One hundred premolars were divided into one control group (Gcontr) (n = 10) and three experimental groups, according to the post-endodontic restoration (n = 30), G1, restored using composite, G2, restored using single fiber post and G3, restored using multifilament fiberglass posts (m-FGP) without post-space preparation. Each experimental group was divided into three subgroups according to the type of coronal cavity configuration (n = 10): G1O, G2O, and G3O with occlusal (O) cavity configuration; G1MO, G2MO, and G3MO with mesio-occlusal (MO); and G1MOD, G2MOD, and G3MOD with mesio-occluso-distal (MOD). After thermomechanical aging, all the specimens were tested under compression load, and failure mode was determined. FEA and WA supplemented destructive tests. Data were statistically analyzed. Irrespective of residual tooth substance, G1 and G2 exhibited lower fracture resistance than Gcontr (p < 0.05), whereas G3 showed no difference compared to Gcontr (p > 0.05). Regarding the type of restoration, no difference was highlighted between G1O and G2O, G1MO and G2MO, or G1MOD and G2MOD (p > 0.05), whereas G3O, G3MO, and G3MOD exhibit higher fracture resistance (p < 0.05) than G1O and G2O, G1MO and G2MO, and G1MOD and G2MOD, respectively. Regarding cavity configuration: in G1 and G2, G1O and G2O exhibited higher fracture resistance than G1MOD and G2MOD, respectively (p < 0.05). In G3, there was no difference among G3O, G3MO and G3MOD (p > 0.05). No difference was found among the different groups and subgroups regarding the failure mode. After aging, premolars restored with multifilament fiberglass posts demonstrated fracture resistance values comparable to those of an intact tooth, irrespective of the different type of cavity configuration.

Cyclic fatigue resistance of Mtwo NiTi rotary instruments used by experienced and novice operators--an in vivo and in vitro study.

BACKGROUND: The aim of the present study was to evaluate the cyclic fatigue resistance of Mtwo NiTi rotary instruments after clinical use by 1 experienced and 1 novice operator. MATERIAL/METHODS: Cyclic fatigue testing of instruments was performed on tapered artificial canals with a 5 mm radius of curvature and 60° angle of curvature. Twenty Mtwo instruments for each size were selected and divided into 2 groups: group A consisted of 10 instruments of each size used for shaping 10 root canals in molar teeth of patients by an experienced operator; group B consisted of 10 instruments of each size used for shaping 10 root canals in molar teeth of patients by a novice operator. Instruments were rotated until fracture occurred and the numbers of cycles to failure (NCF) were recorded. Data obtained were subjected to an independent sample t-test to determine statistical differences. The significance was determined at a 95% confidence level. RESULTS: No statistically significant difference (P<0.05) was noted between the instruments of groups A and B for all sizes. More instruments with visible signs of plastic deformation were identified for the novice operator. CONCLUSIONS: The clinical use of Mtwo NiTi rotary instruments by a novice operator did not significantly affect the cyclic fatigue resistance when compared with the control group of the same instrument sizes used by an experienced operator. It can be concluded that novice operators can use these instruments safely under the recommended technical guidelines.