In Vitro Dental Discoloration Provoked by Intracanal Calcium Silicate-based Dressing Used for Regenerative Endodontic Procedures: An One-year Spectrometric Analysis.

INTRODUCTION: Regenerative endodontic procedures provide conditions for the continuity of apical formation and increase of the dentin wall thickness, being a useful technique to resume root development of necrotic teeth with incomplete apex. This study aimed to evaluate the coronal discoloration promoted by a new intracanal calcium silicate-based dressing and compare it with other intracanal dressings used in regenerative endodontic procedures. METHODS: Sixty bovine incisors were prepared to simulate teeth with incomplete apexes and divided according to the intracanal dressing used: triple antibiotic paste-double antibiotic paste-DAP, calcium hydroxide associated with 2% chlorhexidine gel, calcium hydroxide associated with saline solution, and Bio-C Temp. As control, no dressing was performed. The intracanal dressings remained in the simulated root canal for 21 days. Luminosity (ΔL) and color difference (ΔEab and ΔE00) were evaluated using long-term (1 year) spectrophotometric analysis. The results were analyzed using the ANOVA test with Tukey post hoc with a significance of 5%. RESULTS: Triple antibiotic paste showed the highest values of ΔEab and ΔE00 and lowest values of ΔL (P < .05). Bio-C Temp showed higher ΔEab than the other groups from 6 months (P < .05), higher ΔE00 and lower ΔL after 1 year (P < .05). CONCLUSIONS: Bio-C Temp induced noticeable coronary discoloration after the 1-year analysis.

Evaluation of irrigant extrusion following the use of different root canal irrigation techniques: A systematic review and meta-analysis.

This systematic review investigates whether different irrigation techniques have different effects on irrigant extrusion from mature tooth apices. Articles published between January 2000 and January 2022 were searched in six electronic databases (MEDLINE, Embase, Google Scholar, Web of Science, Scopus and Cochrane) using appropriate keywords. Overall, 2265 articles were screened by their titles and abstracts. Fifty-six full-text articles were selected based on the inclusion criteria. Of them, 17 in vitro studies were included in the systematic review and meta-analysis. The meta-analysis was conducted using the random-effects inverse variance method. The results showed that the negative pressure technique caused a lesser amount (p = 0.00) and frequency (p = 0.00) of extrusion than the open-ended needle irrigation. Sonic and ultrasonic activation caused less amount of extrusion than both open-ended (p = 0.00 or p = 0.01) and closed-ended needle (p = 0.00) irrigation.

The frequency of sodium hypochlorite extrusion during root canal treatment: an observational clinical study.

BACKGROUND: To determine the frequency of sodium hypochlorite (NaOCl) extrusion and evaluate the outcome of the injury. METHODS: A total of 1123 teeth indicated root canal treatment were included. An open-ended needle was used during/after the instrumentation. Acute burning pain during irrigation was considered as NaOCl extrusion. Negative aspiration was applied for patients with extrusion, and appropriate treatment was planned due to the symptoms. The number of patients who experienced extrusion and symptoms were recorded. Analysis of variance (ANOVA), at P < 0.05, was used to compare the data groups. RESULTS: NaOCl extrusion rate was found at 0.89%, and the injury with swelling that differential diagnosis of NaOCl accident caused by extrusion rate was 0.18%. The most common findings besides acute pain, as a sign of extrusion (n = 10), were accompanying apical bleeding (n = 6) and swelling (n = 2). According to the number of visits, a significant correlation was found between the symptoms (P = 0.010). No serious injury such as a neurological sign, tissue necrosis or trismus occurred in any patient. CONCLUSIONS: Demographic characteristics of the patients and preoperative condition of teeth were not related to NaOCl extrusion. The increasing number of visits may affect the probability of an accident. Negative aspiration immediately may be crucial in preventing severe injuries.

[Study on the influence of passive ultrasonic irrigation on debris cleaning ability and root canal shape].

PURPOSE: To evaluate the safety and effectiveness of passive ultrasonic irrigation(PUI) in curved root canals, and debris cleaning ability and the amount of root canal transportation of passive ultrasonic irrigation(PUI) in curved root canals. METHODS: A total of 36 mesially curved root canals of mandibular molars with a curvature above 25° were selected. The root canals were prepared with XP-endo Shaper root canal file. The samples were divided into A1 group (curved length＞3 mm, syringe irrigation), B1 group(curved length＞3 mm, PUI+K file), C1 group(curved length＞3 mm, PUI+irrisafe), A2 group (curved length＜3 mm, syringe irrigation), B2 group (curved length＜3 mm, PUI+K file), and C2 group (curved length＜3 mm, PUI+ irrisafe) (n=6). Micro-CT scans were performed on all samples before and after irrigation, and the volume increase in the root canal after irrigation and the transportation of the root canal were calculated. SPSS 22.0 software package was used to analyze the data. RESULTS: In the apical area of the root canal with a curved length greater than 3 mm, the root canal volume increase in the PUI+irrisafe group was significantly greater than that of the PUI+K file and syringe irrigation (P＜0.05), and at 5 mm section, the transportation of the root canal formed by PUI+irrisafe was significantly lower than that of the PUI+K file (P＜0.05), but there was no significant difference from syringe irrigation (P＞0.05); in root canals with a curved length less than 3 mm, root canal volume increment of the file group was significantly greater than that of syringe irrigation (P＜0.05), but there was no significant difference between the root canal transportation and syringe irrigation(P＜0.05). CONCLUSIONS: In root canals with larger curved length, passive ultrasonic irrigation combined with a pre-curved file can obtain a better cleaning effect, while in root canals with smaller curved length, both K file and pre-curved file with passive ultrasonic irrigation are safe and effective.

Accidental Extrusion of Sodium Hypochlorite in a Patient Taking Alendronate: A Case Report With an 8-Year Follow-up.

Extrusion of sodium hypochlorite (NaOCl) is a very rare accident with the most common complications including pain, swelling, and hematoma. It can occur even if procedural guidelines, predisposing conditions, and risk factors are taken into consideration. A 59-year-old female patient was admitted to the endodontics department to treat a left maxillary first premolar (World Dental Federation tooth 24). The medical history included osteoporosis and systemic medication with alendronate. Initially, the diagnosis was "symptomatic irreversible pulpitis" with "normal apical tissues." During instrumentation of the buccal canal, accidental extrusion of 2.5% NaOCl occurred into the periapical tissues, resulting from misinterpretation of the working length, and caused severe pain and bleeding. The canal was immediately flushed using copious irrigation with saline solution. An analgesic and corticosteroid were prescribed. At 3 and 7 days, ecchymosis and slight hematoma were observed extraorally in the area of the affected tooth and an intraoral ulceration at the apex of the affected tooth. At 15 days, minimal signs of ecchymosis were observed, and the treatment was resumed. At 30 days after the accident, there was complete remission of the sequelae. The clinical, radiographic, and tomographic assessment after 1 month, 1 year, and 8 years showed favorable case evolution. During the 8-year follow-up, the patient maintained the systemic use of alendronate. It can be concluded that NaOCl extrusion is an accident that causes patients and clinicians to experience an unpleasant consequence. The radiographic working length should always be determined carefully. A successful outcome can be achieved in patients who take alendronate.

Efecto de los extractos fitoquímicos en la eliminación del barro dentinario en el tratamiento de conductos radiculares / Effects of phytochemical extracts on smear layer removal in root canal treatment

Introduction: Studies suggested that phytochemical products are considered potential solutions to smear layer removal due to their biological safety in cleaning root canal systems, lower toxicity, lower irritant effect and antimicrobial effect. Objective: The aim of the present study was to perform a systematic review to evaluate smear layer removal of root canal systems by different natural product solutions. Methods: systematic review. Search of the literature was performed on Pubmed, Scopus, Cochrane, Web of Science, Scielo and Google Scholar according the PRISMA protocol. Studies were included if they performed the experiments of smear layer removal on extracted permanent human teeth. Articles published in any language without restriction of year of publication were included in this review. The risk of bias assessment in the included studies was evaluated using the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. The search strategy resulted in the retrieval of 6221 publications. After the eligibility criteria application, 8 articles were selected for analysis. Results: It was observed that some natural products solutions showed effects on smear layer removal, especially on coronal third. The phytochemical products such as Salvadora persica, chamomile alcohol extract and grape seed extract demonstrated good potential of smear layer removal, however, its effectiveness and clinical applicability are still unclear. Conclusions: Although the limitations of this study, it is possible to highlight those phytochemical products such as Salvadora persica, chamomile alcohol extract and grape seed extract that demonstrated good potential on SL removal(AU)

Introducción: Los productos fitoquímicos se consideran soluciones potenciales para la eliminación del barro dentinario debido a su seguridad biológica en la limpieza del sistema de conductos radiculares, menor toxicidad, menor efecto irritante y efecto antimicrobiano. Objetivo: Evaluar la eliminación del barro dentinario de los sistemas de conductos radiculares mediante diferentes soluciones de productos naturales. Métodos: La búsqueda de la literatura se realizó en Pubmed, Scopus, Cochrane, Web of Science, SciELO y Google Scholar, según el protocolo PRISMA. Los estudios se incluyeron si realizaron los experimentos de eliminación del barro dentinario en dientes humanos permanentes extraídos. En esta revisión se incluyeron artículos publicados en cualquier idioma, sin restricción de año de publicación. La evaluación del riesgo de sesgo en los estudios incluidos se evaluó mediante la lista de verificación de evaluación crítica del Instituto Joanna Briggs para estudios cuasiexperimentales. La estrategia de búsqueda resultó en la recuperación de 6221 publicaciones. Después de la aplicación de los criterios de elegibilidad, se seleccionaron 8 artículos para su análisis. Resultados: Se observó que algunas soluciones de productos naturales mostraron efectos sobre la eliminación del barro dentinario, especialmente en el tercio coronal. Los productos fitoquímicos como salvadora pérsica, extracto de alcohol de manzanilla y extracto de semilla de uva demostraron un buen potencial de eliminación del barro dentinario; sin embargo, su efectividad y aplicabilidad clínica aún no están claras. Conclusiones: A pesar de las limitaciones de este estudio, es posible destacar aquellos productos fitoquímicos como salvadora pérsica, extracto de alcohol de manzanilla y extracto de semilla de uva demostraron buen potencial de eliminación del barro dentinario(AU)

Sodium Hypochlorite Extrusion Accidents: Management and Medico-Legal Considerations.

Sodium hypochlorite is considered the most widely used irrigant in endodontics as it exhibits effective antimicrobial activity and has potent tissue-dissolving ability. Whilst it is considered safe when used within the confines of the root canal system, it can cause serious complications when inadvertent periradicular extrusion occurs. This article outlines the complications of sodium hypochlorite extrusion and reviews the appropriate management based on the contemporary evidence. Preventive measures are suggested and the relevant medico-legal considerations are outlined.

Direct and Indirect Effect of Chlorhexidine on Survival of Stem Cells from the Apical Papilla and Its Neutralization.

INTRODUCTION: Several irrigants have been used for disinfection in regenerative endodontic procedures including chlorhexidine (CHX). In this context, the antibacterial properties of disinfectants are mainly in focus of research even though they may have an undesirable impact on the fate of stem cells. In this study, we hypothesized that CHX has both a direct effect when applied to stem cells of the apical papilla (SCAPs) and an indirect effect when SCAPs are exposed to dentin previously conditioned with CHX. METHODS: Cell toxicity was evaluated in vitro using the CellTox green fluorescence assay (Promega, Madison, WI) and CellTiter-Glo (Promega) after SCAPs were exposed directly to a dynamic concentration range of CHX; apical papilla explant cultures were stained with ApopTag (Merck Millipore, Billerica, MA) after culture with CHX. Furthermore, standardized slabs from human dentin were treated with CHX and consecutively rinsed in EDTA, L-α-lecithin (Sigma-Aldrich, St Louis, MO), or L-α-lecithin followed by EDTA. After that, SCAPs were cultured on the slabs for 5 days, and cellular viability was determined (indirect effect). Data were treated nonparametrically and analyzed using the Krukal-Wallis test (P ≤ .05). RESULTS: Direct exposure of SCAPs to CHX highly affected cell viability at concentrations above 10-3%, whereas lower concentrations had no adverse effect. During the initial 60 minutes, concentrations of 10-2% CHX or higher resulted in early pronounced toxicity with a maximum effect within 15 minutes after exposure. Likewise, CHX-conditioned dentin slabs were detrimental to SCAP survival; however, the deleterious effects were completely reversed by neutralization with L-α-lecithin. CONCLUSIONS: Chlorhexidine is toxic to SCAPs when applied directly or indirectly via conditioned dentin. If applied for a short time and neutralized by L-α-lecithin, it can be a gentle and cell-preserving disinfectant before endodontic regeneration.

Effect of Temperature of Sodium Hypochlorite on Cyclic Fatigue Resistance of Heat-treated Reciprocating Files.

INTRODUCTION: The aim of this study was to evaluate the effect of different temperatures of sodium hypochlorite (NaOCl) on the cyclic fatigue resistance of the heat-treated file systems. METHODS: The cyclic fatigue resistance of Reciproc 25 (VDW Dental, Munich, Germany), Reciproc Blue R25 (VDW), WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland), WaveOne Gold Primary (Dentsply Maillefer), and One Shape (25.06; Micro Mega, Besançon, France) was tested in the following conditions: control (no immersion), immersion in distilled water (DW) at 37°C ± 1°C, immersion in DW at 60°C ± 1°C, immersion in NaOCl at 37°C ± 1°C, and immersion in NaOCl at 60°C ± 1°C. The immersion period was 5 minutes for all conditions. A stainless steel artificial canal with a curvature of 60° and a 5-mm radius was used. The time to failure and fragment lengths were recorded for each instrument, and data were subjected to statistical analysis. RESULTS: Reciproc Blue showed greater cyclic fatigue resistance in all conditions compared with the other systems (P < .05). Immersion in NaOCl at 60 °C negatively affected all instruments' cyclic fatigue resistance except Reciproc Blue. Immersion in DW at 60 °C increased the cyclic fatigue resistance of Reciproc Blue. Heat-treated files presented higher fatigue resistance than traditional files. CONCLUSIONS: A high temperature of NaOCl affected the cyclic fatigue life of the file systems. Instruments produced with heat treatment presented a longer fatigue life.

Removal of Calcium Hydroxide from Artificial Grooves in Straight Root Canals: Sonic Activation Using EDDY Versus Passive Ultrasonic Irrigation and XPendo Finisher.

INTRODUCTION: The aim of the present study was to compare sonic activation using EDDY (VDW, Munich, Germany), passive ultrasonic irrigation (PUI), and mechanical activation using the XPendo Finisher (FKG Dentaire, La Chaux-des-Fonds, Switzerland) for the removal of calcium hydroxide from artificial grooves in straight root canals. METHODS: The root canals of 90 human maxillary incisors with straight root canals were prepared using Mtwo files (VDW) up to size 40/.04, and the teeth were split longitudinally. A lateral groove in the apical or coronal part was prepared in each root half and filled with calcium hydroxide, and the root halves were reassembled. Five groups were established according to the removal techniques: group A, the XPendo Finisher; group B, EDDY; group C, PUI; group D, manual irrigation with a syringe; and group E, no irrigation (the control group). The activation procedures were performed for 30 seconds with 3 mL sodium hypochlorite 3% as the irrigant. The cleanliness of the grooves was scored under 10× magnification. The median of scoring was analyzed using the Kruskal-Wallis test (P = .05). RESULTS: All activation techniques were significantly more effective in the removal of calcium hydroxide than manual irrigation (P < .05). Regarding the apical groove, EDDY and PUI were significantly more effective in the removal of calcium hydroxide than the XPendo Finisher (P < .05). No difference was found for the coronal groove (P > .05). CONCLUSIONS: EDDY and PUI were significantly more effective in the removal of calcium hydroxide than the XPendo Finisher regarding the apical region. Manual irrigation was significantly less effective than all activation techniques.

Influence of the Vehicle and Antibiotic Formulation on Cytotoxicity of Triple Antibiotic Paste.

INTRODUCTION: The aim of this study was to assess the influence of antibiotic formulations (tablet/capsule [TC] or United States Pharmacopeia [USP]-grade antibiotics) and vehicles (water [H2O] or macrogol + propylene glycol [MP]) on the cytotoxicity and pH of triple antibiotic pastes (TAPs). METHODS: L929 fibroblasts were exposed to TAPs prepared with TC or USP-grade antibiotics mixed with H2O or MP for 72 hours. Each isolated antibiotic with each vehicle, each isolated vehicle, and the culture medium were used as controls. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and neutral red assays. The pH was measured after 3 and 8 hours of immersion of the pastes in water. Data were analyzed using analysis of variance, the Bonferroni or Tukey posttests (α = 0.05), and the Pearson correlation test (α = 0.05). RESULTS: The pastes prepared with TC were less cytotoxic than pastes prepared with USP-grade antibiotics (P < .05), and pastes with the MP vehicle were less cytotoxic than pastes with H2O (P < .05). TC TAP + MP showed the lowest cytotoxicity, whereas USP-grade TAP + H2O showed the highest cytotoxicity (P < .05). All TAPs showed a pH ranging from 4.64-5.20. Irrespective of the vehicle, USP-grade TAP showed a lower pH than TC TAP (P < .05). TAPs with H2O had a lower pH than TAPs with MP (P < .05). CONCLUSIONS: The vehicle and the antibiotic formulations influenced the cytotoxicity and pH of TAP. The pastes prepared with TC and MP were less acidic and less cytotoxic than the type prepared with USP-grade antibiotics and H2O.

Effects of Final Irrigation with SmearOFF on the Surface of Dentin Using Surface Analytical Methods.

INTRODUCTION: SmearOFF (Vista Dental Products, Racine, WI) is an irrigation solution containing chlorhexidine (CHX), EDTA, and a surfactant. This study examined the chemical interaction of SmearOFF with sodium hypochlorite (NaOCl) on the dentin surface, specifically the formation of precipitate and/or parachloroanaline (PCA). METHODS: Dentin blocks prepared from human maxillary molars were mounted in resin. Dentinal tubules were exposed in a perpendicular orientation using an ultracryomicrotome. The blocks were divided into 2 groups: the CHX group, irrigation with 6% NaOCl, 17% EDTA, 6% NaOCl, and 2% CHX, and the SmearOFF group, irrigation with 6% NaOCl and SmearOFF. The dentin surface was analyzed with time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy to determine the formation of precipitate or/and PCA on the surface of dentin. RESULTS: Precipitation with PCA and occlusion of the dentinal tubules were noted on the dentin surface in the CHX group. No precipitate and no PCA were detected on the surface of dentin in the SmearOFF group. CONCLUSIONS: Interaction of SmearOFF with NaOCl on the dentin surface did not result in the formation of precipitate or PCA.

Laser therapy as an adjunct in the treatment of sodium hypochlorite extrusion through a root perforation: a case report.

Accidental sodium hypochlorite extrusion can occur during endodontic irrigation procedures. The symptoms appear immediately and include severe pain, swelling, and probable tissue necrosis adjacent to the root of the treated tooth. Treatment of sodium hypochlorite extrusion involves immediate and copious saline irrigation to neutralize the area and prescription of analgesic, anti-inflammatory, and antibiotic medications. Low-level laser therapy (LLLT) might be useful as an adjuvant treatment for damaged soft tissues to improve healing. This case report describes the treatment of accidental extrusion of 1% sodium hypochlorite through a root canal perforation in a mandibular incisor during endodontic treatment. The extrusion caused minor swelling within the mentolabial sulcus and a large area of necrosis in the gingivolabial mucosa and right edentulous premolar area. Conventional treatment was performed in association with LLLT. Clinical and radiographic examinations after 6 months showed complete healing of the necrotic area without paresthesia and the repair of apical tissues.

Effect of Endodontic Irrigation Protocols on Crown Fracture Resistance.

AIM: This study aimed to evaluate the fracture resistance of tooth crowns endodontically irrigated using different protocols. MATERIALS AND METHODS: A total of 76 bovine incisors were divided into four groups (n = 19): irrigation with distilled water (control; CON); conventional irrigation with positive apical pressure (PAP); passive ultrasonic irrigation using continuous flushing (PUI); and irrigation with PAP and heated sodium hypo-chlorite solution (PHS). The force required to fracture the crown was measured on a universal testing machine at an angle of 45°. RESULTS: The CON group had higher fracture resistance (351.71 ± 58.66 N) than the PAP and PUI groups (140.96 ± 37.26 N; 167.49 ± 40.08 N respectively). The PHS group had the lowest fracture resistance value (115.15 ± 41.07 N). Irrigation protocols had a significant effect on crown resistance (p < 0.01). CONCLUSION: Teeth subjected to irrigation with heated sodium hypochlorite showed decreased resistance to crown fracture. CLINICAL SIGNIFICANCE: The contact of the irrigating solution with the root canal walls potentially can cause their weakness, determining crown fracture.

Hypochlorite accident during wndodontic therapy with nerve damage - A case report.

Endodontic therapy is a routinely practised clinical procedure with few reported complications but, as a bleaching agent, inadvertent spillage of sodium hypochlorite beyond the root canal system may result in extensive soft tissue or nerve damage, and even airway compromise. Although very rare, complications arising from hypochlorite extrusion beyond the root apex are described. NaOCl causes oxidation of protein and lipid membrane and causes necrosis, hemolysis and dermal ulcerations (2-4). Neurological complication are very rare. Paraesthesia and anaesthesia may affect the mental, inferior dental and infra-orbital branches of the trigeminal nerve and normal sensation may take many months to  completely resolve (6, 7). Nerve damage (the buccal branch) was described in 2005 by Witton et al. (8) and patients exhibited a loss of the naso-labial groove and a down turning of the angle of the mouth and the motor function was regained after several months. We present a case in which the extrusion of NaOCl solution during endodontic therapy led to important destructive effects on soft tissues and nerves. The arisen medico legal issues are discussed.

Root Canal Irrigants and Medicaments in Endodontic Malpractice Cases: A Nationwide Longitudinal Observation.

INTRODUCTION: The aim of this study was to assess the role of root canal irrigants and medicaments in endodontic injuries verified in Finland and to estimate the rate of such events over time. METHODS: The study material comprised all endodontic injuries verified by the Patient Insurance Centre in 2002 to 2006 (n = 521) and 2011 to 2013 (n = 449). The data, based on patient documents scrutinized by 2 specialists in endodontics, included patients' and dentists' sex and age and the service sector. We recorded the use of root canal irrigants and medicaments, each as a dichotomy. Furthermore, we dichotomized the injuries as those related to root canal irrigants/medicaments and any other injuries. The injuries were also dichotomized as avoidable (could have been avoided by following good clinical practice) or unavoidable (normal treatment-related risks). Statistical evaluation used chi-square tests and t tests; logistic regression produced odds ratios (ORs). RESULTS: The verified injuries (N = 970) comprised 635 (65%) avoidable and 335 (35%) unavoidable injuries. The number of irrigant-/medicament-related injuries was 69, accounting for 7.1% of all verified injuries; all resulted from sodium hypochlorite and calcium hydroxide, and 87% were avoidable. The overall rate of sodium hypochlorite/calcium hydroxide injuries was 4.3 cases per 100,000 endodontic patients per year. Compared with other injuries, sodium hypochlorite/calcium hydroxide injuries were more likely avoidable (OR = 3.8) and more than 5-fold likely in 2011 to 2013 than in 2002 to 2006 (OR = 5.6). CONCLUSIONS: Extreme care is needed when applying sodium hypochlorite and calcium hydroxide into root canals to avoid increasing harmful consequences.

Sodium Hypochlorite Accident: A Systematic Review.

INTRODUCTION: Sodium hypochlorite (NaOCl) extrusion beyond the apex, also known as "a hypochlorite accident," is a well-known complication that seldom occurs during root canal therapy. These "accidents" have been the subject of several case reports published over the years. Until now, no publication has addressed the global synthesis of the general and clinical data related to NaOCl extrusion. The main purpose of this article was to conduct a systematic review of previously published case reports to identify, synthesize, and present a critical analysis of the available data. A second purpose was to propose a standardized presentation of reporting data concerning NaOCl extrusions to refine and develop guidelines that should be used in further case report series. METHODS: A review of clinical cases reporting NaOCl accidents was conducted in June 2016 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist; it combined an electronic search of the PubMed database and an extensive manual search. RESULTS: Forty full-text articles corresponding to 52 case reports published between 1974 and 2015 were selected. Four main categories of data were highlighted: general and clinical information, clinical signs and symptoms of NaOCl extrusions, management of NaOCl extrusions, and healing and prognosis. Overall, up to now, clinical cases were reported in a very unsystematic manner, and some relevant information was missing. CONCLUSIONS: A better understanding of the potential causes, management, and prognosis of NaOCl accidents requires a standardization of reported data; this study proposes a template that can fulfill this objective.

Uncontrolled Removal of Dentin during In Vitro Ultrasonic Irrigant Activation in Curved Root Canals.

INTRODUCTION: The aim of this study was to examine the effect of file type and activation time on the uncontrolled removal of dentin during in vitro ultrasonic irrigant activation in prepared curved root canals. METHODS: Seventy-two curved mesial root canals of human mandibular molars were prepared to size 35/.04 taper. The specimens were randomly allocated to 4 groups (n = 18). Two milliliters of 2% sodium hypochlorite were delivered 3 times to each root canal, and the irrigant was ultrasonically activated every time for 10 seconds at 35% power either by a ultrasonic K-file (group A), an Irrisafe file (Acteon Satelec, Merignac, France) (group B), or a smooth wire (group C). The same specimens also received further activation continuously for another 30 seconds. No activation took place in group D. Specimens were scanned by micro-computed tomographic imaging before and after preparation and after the first and second activation period. Scans were coregistered and segmented, and the amount of dentin removed during activation was quantified by morphological operations. Results were analyzed by nonparametric statistical tests (α = 0.05). RESULTS: Defects with a maximum depth of 0.18 mm were identified. Both the type of file and activation time affected the removal of dentin (P ≤ .002 and P ≤ .031, respectively). K-files removed more dentin than Irrisafe files and smooth wires in the coronal and middle third. All files removed comparable amounts in the apical third. CONCLUSIONS: All 3 types of files may result in uncontrolled removal of dentin. A longer activation time may increase this effect.