Root Canal Walls Research Articles

The Effect of Apical Preparation Size on the Removal of Smear Layer and Organic Debris from Root Canal Wall: An In-vitro Scanning Electron Microscopic Study

The Effect of Apical Preparation Size on the Removal of Smear Layer and Organic Debris from Root Canal Wall: An In-vitro Scanning Electron Microscopic Study

Influence of a colloidal silver dioxide solution on the edge adjustment of the mineral aggregate trioxide cement for closure of perforation communications <i>in vitro</i>

BACKGROUND: According to Russian and foreign literature, the probability of iatrogenic perforation of the wall of the tooth root canal is high (9.712.5%) during endodontic dental treatment. This is a poor prognostic sign and may subsequently result in tooth extraction. Moreover, cases without curing of mineral trioxide aggregate (MTA) cement with pronounced exudation were reported. Сurrently, the modification of domestically produced MTA cement is relevant for closing teeth root canal perforation.
 AIM: This study aimed to conduct a comparative experimental microscopic study of the preservation of the marginal fit to the tooth tissues in perforation areas filled with MTA cement mixed conventionally with distilled water and a colloidal silver dioxide solution.
 MATERIALS AND METHODS: Sixty teeth previously removed for medical reasons were endodontically treated after iatrogenic perforation formation in the furcation area of the roots. Two groups were formed. In the first group, MTA cement mixed with distilled water was used to close dental perforations. In the second group, MTA cement mixed with a colloidal silver dioxide solution was utilized. The groups were divided into subgroups depending on the MTA cement brand used. The teeth were placed in an automatic incubator HHD 7 LED, in which an optimal mode was created, simulating the conditions of the oral cavity (t = 37 C, humidity 99%). The samples were placed in artificial saliva. After two months of exposing the teeth to a humid environment, the preservation and damage to the marginal fit in the perforation area of the fillings were determined under a Levenhuk 720B binocular microscope.
 RESULTS: In the perforations of the 30 teeth sealed with various MTA cement types mixed with distilled water, damage of the marginal fit was found in seven (23.3 7.9%) cases. Similar damage in 30 teeth with colloidal silver dioxide solution used to prepare MTA cements was detected in two (6.7 4.6%) cases (p 0.050, t = 1.82).
 CONCLUSION: The use of MTA cement mixed in a colloidal silver dioxide solution, in comparison with distilled water, contributes to a greater preservation of the marginal fit of the material to the walls of the root canal in an in vitro experiment.

Patterns of stress distribution of endodontically treated molar under different types of loading using finite element models—the exploring of mechanism of vertical root fracture

IntroductionThe purpose of this study was to explore the mechanism of vertical root fracture (VRF) using three-dimensional finite element models (FEMs). MethodsAn endodontically treated mandibular first molar with a subtle VRF was collected and scanned with cone beam CT (CBCT). Three finite element analysis models were created: Model 1 had the actual endodontically treated root canal size; Model 2 had the same root canal size as the contralateral homonymous tooth; and Model 3 had the root canal size expanded by 1 mm based on Model 1. Different types of loading were performed on these 3 FEMs. The stress distribution on the cervical, middle, and apical planes was analyzed, and the maximum stress on the root canal wall was calculated and compared. ResultsIn Model 1, the maximum stress around the root canal wall occurred in the cervical part of the mesial root under vertical masticatory force and in the middle part of the mesial root under buccal and lingual lateral masticatory forces. Additionally, there was a stress change zone in a bucco-lingual direction that corresponded with the actual fracture line. In Model 2, the maximum stress around the root canal was in the cervical part of the mesial root under both vertical and buccal lateral masticatory forces. For Model 3, the stress distribution was similar to that of Model 1, but greater under buccal lateral masticatory force and occlusal trauma force. In all three models, the maximum stress around the root canal wall was in the middle part of the distal root under occlusal trauma force. ConclusionsThe uneven stress around the root canal in the middle part (presented as a stress change zone in a bucco-lingual direction) may be the cause of VRFs.

Volume and Power of Expansion of Novel Polyurethane-based Sealers

IntroductionShrinkage and lack of interfacial adaptation between endodontic sealers and root canal walls may jeopardize the root canal treatment outcome. This study aimed to evaluate the volume and power of expansion (and the relationship between the two) of three novel root canal sealers (polyurethane expandable sealer [PES], zeolite + PES [ZPES], and elastomeric polyurethane sealer [EPS]) in comparison with an epoxy-resin based sealer (AH Plus) and a calcium silicate-based sealer (EndoSequence BC). MethodsThis study utilized 36 cylinders (30 plastic graduated cylinders for volume of expansion and 6 steel cylinders for power of expansion) (4 × 10 mm) filled with PES, ZPES, EPS, AH Plus, EndoSequence BC, or water (n = 5/group). The plastic graduated cylinders were inserted inside a customized Linear Swell Meter apparatus to measure the percentage of volumetric expansion. The steel cylinders were placed inside a Linear Swell Meter apparatus mounted onto a universal testing machine to measure the maximum pressure in psi. Specimens were tested for 72 hours for both volume and power of expansion tests. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, Post Hoc Tukey, and Pearson correlation tests (P < .05). ResultsThe volume of expansion of PES, ZPES, and EPS was significantly higher than in AH Plus and EndoSequence BC (P < .05). For the power of expansion, no significant differences were found between the root-filling materials (P > .05). No correlation was seen between the volume and power of expansion (P > .05). ConclusionAlthough polyurethane-based sealers showed a significantly higher volume of expansion compared to AH Plus and EndoSequence BC, their power of expansion did not increase significantly.

Photodynamic therapy on the extrusion bond strength of gutta-percha to radicular dentin sealed with bioceramic and conventional sealers.

The aim of this study was to evaluate the influence of photodynamic therapy (PDT) on the extrusion bond strength (EBS) of gutta-percha to radicular dentin sealed with bioceramic sealers. Sixty human-extracted mandibular premolars were used in the present study, being decoronated up to the cementoenamel junction, and secured in heat cure acrylic resin for root canal therapy. The specimens were randomly divided into groups based on conventional [2.25% sodium hypochlorite (NaOCl) + 17% EDTA] and disinfection protocols (2.25% NaOCl + PDT + 17% EDTA) (n = 10). Specimens in groups 1, 3, 5: conventional treatment modality (2.25% NaOCl + 17% EDTA). Samples in groups 2, 4, 6: adjunctive PDT treatment modality (2.25% NaOCl+ PDT+ 17% EDTA). Specimens in groups 1 and 2 were sealed with AH Plus sealer (AH). Specimens in groups 3 and 4 were sealed using Endo Sequence BC sealer, and samples in groups 5 and 6 were sealed with MTA Fillapex. All specimens were cut in the coronal and middle segments and positioned in a universal testing machine (UTM) for assessment of extrusion bond strength (EBS). ANOVA and Post-Hoc Tukey multiple comparison tests were applied for performing statistical analysis (p < 0.05). Coronal root samples in group 1 (2.25% NaOCl + 17% EDTA) sealed with AH Plus sealer demonstrated the highest EBS value (9.21 ± 0.62 MPa) whereas the middle-third of specimens in group 6 (2.25% NaOCl + PDT + 17% EDTA) sealed with MTA Fillapex exhibited the lowest EBS value (5.07 ± 0.17 MPa). Intergroup comparison revealed that group 3 (2.25% NaOCl + 17% EDTA) sealed with Endo Sequence BC Sealer and group 5 (2.25% NaOCl + 17% EDTA) sealed with MTA Fillapex disclosed comparable EBS results to group 1 (p > 0.05) while group 2 (2.25% NaOCl + PDT + 17% EDTA) sealed with AH Plus sealer and group 4 (2.25% NaOCl + PDT + 17% EDTA) sealed with Endo Sequence BC Sealer unveiled analogous EBS values to group 6 (2.25% NaOCl + PDT + 17% EDTA) MTA Fillapex (p > 0.05). The most noticeable failure mode in the coronal and middle thirds of non-PDT subjected groups was cohesive. Combination of 2.25% NaOCl with PDT and 17% EDTA for canal disinfection with AH Plus sealer, calcium silicate sealer, and MTA-based bioceramic sealers have an unfavorable effect on the EBS of gutta-percha to the root canal wall.

ОСОБЕННОСТИ ЭНДОДОНТИЧЕСКОГО ЛЕЧЕНИЯ ЗУБОВ С ЭНДОПАРОДОНТАЛЬНЫМ ПОРАЖЕНИЕМ КАК ЗАЛОГ КАЧЕСТВЕННОГО ПРОТЕЗИРОВАНИЯ

The problem of treatment of teeth with endoparodontal lesions remains relevant today. This article discusses a clinical case of treatment of a patient with chronic generalized periodontitis who has a combined lesion of the periodontal and apical periodontal in the lower premolar region. The purpose of the study is evaluation of the effectiveness of the treatment of endoparodontal tooth lesion and the further possibility of prosthetics of the tooth. Materials and methods. For the diagnosis of pathology and in the course of treatment, the following additional research methods were used: CT, OPTG and targeted radiography. Mechanical processing was carried out with manual steel tools. Drug treatment was carried out using solutions of 3% sodium hypochlorite and 17% EDTA For temporary obturation of the root canal, a material based on calcium hydroxide with the addition of a radiopaque substance was used. To further improve the quality of disinfection and adhesion of the filling material to the root canal wall, the method of photodynamic action on the root canal wall was applied in the 2nd visit. Permanent obturation of the root canal was carried out by the method of lateral condensation of gutta-percha in combination with a siler based on ecoxide resin. The reduction of the focus of bone tissue destruction was confirmed clinically and radiologically. Thus, we managed to avoid tooth extraction and it became possible to use this tooth as a support on a non-removable orthopedic structure.

Cleaning and Disinfecting Oval-Shaped Root Canals: Ex Vivo Evaluation of Three Rotary Instrumentation Systems with Passive Ultrasonic Irrigation.

Background and Objectives: Successful root canal treatment depends on the thorough removal of biofilms through chemomechanical preparation. This study aimed to investigate and compare the cleaning and disinfecting efficiency of oval-shaped root canals using XP-endo Shaper (XPS), ProTaper Next (PTN), and HyFlex CM (HCM) in combination with passive ultrasonic irrigation (PUI). Materials and Methods: Ninety extracted teeth were contaminated and randomly divided into three groups: XPS, PTN, and HCM. Each group was assigned to three subgroups: subgroup A (sterile saline), subgroup B (3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid), and subgroup C (3% sodium hypochlorite, 17% ethylenediaminetetraacetic acid, and PUI). Bacterial sampling was conducted both from baseline samples and samples after chemomechanical preparation. Scanning electron microscopy (SEM) was used to evaluate the residue bacterial biofilms, hard tissue debris, and smear layers on the buccolingual walls of oval-shaped root canals. Results: When combined with sterile saline, XPS demonstrated a higher reduction of bacterial counts and was more effective in eradicating Enterococcus faecalis in the middle third of the canals compared to the other instruments (p < 0.05). Additionally, when used with antimicrobial irrigants, XPS was more effective in disinfecting the coronal third of the canals than the other instruments (p < 0.05). Furthermore, XPS reduced hard tissue debris more effectively in the middle third of canals than in the apical third (p < 0.05). Conclusions: XPS outperforms PTN and HCM in disinfecting oval-shaped root canals. Despite the fact that combining XPS and PUI improves cleaning and disinfecting, removing hard tissue debris from the critical apical area remains challenging.

A Novel Endodontic Approach in Removing Smear Layer Using Nano and Submicron Diamonds with Intracanal Oscillation Irrigation.

Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are commonly recommended for effectively removing organic and inorganic components in the smear layer. This layer is found on root canal walls after root canal instrumentation. However, high-concentration EDTA reduces the strength of dentin and the dissolution efficacy of organic substances in NaOCl solution. The objective of this study was to investigate the efficacy of applying nano and submicron diamonds in irrigation solutions with sonic and ultrasonic oscillation for removing the smear layer during endodontic treatment. Extracted single-rooted human teeth were instrumented with ProTaper® Gold (Dentsply Sirona) nickel-titanium rotary instruments. Subsequently, each canal was irrigated with 3% NaOCl, 17% EDTA, distilled water, and 10-1000 nm-sized nano and submicron diamond irrigation solutions, respectively. Sonic and ultrasonic instruments were compared for oscillating the irrigation solutions. The teeth were processed for scanning electron microscopy to observe the efficiency of smear layer removal on the canal walls. Our results indicated that diamond sizes of 50 nm and above irrigation solutions showed significant effectiveness in removing the smear layer following the oscillation of sonic instruments for 10 s. Ultrasonic assisted 500 nm and 1000 nm diamond solutions significantly differed from the other diamond-sized solution in their ability to remove the smear layer. These results suggest that sonic and ultrasonic oscillation with specific sizes of nano and submicron diamond irrigation solution can be used as an alternative approach to removing the smear layer during endodontic treatment. The potential clinical application of root canal treatments can be expected.

DIFFERENCES IN TOOTH DISCOLORATION BETWEEN ZINC OXIDE EUGENOL AND MINERAL TRIOXIDE AGGREGATE-BASED SEALERS (LITERATURE STUDY)

Endodontic treatment is a common procedure in dentistry. One of the steps in endodontic treatment is obtura-tion root canal, that needed application sealer to seal the gap between dentin's wall and gutta-percha and lubricate the root canal's wall during treatment. Sealer can cause discoloration because of their compositions such as eugenol, phenol, and silver that is potential in causing color alteration. Objective: to analyze the discoloration difference in application using ZOE sealer and MTA sealer. Method: Journals, textbooks, and websites published between 2010 – 2020 and can be accessed from Google Scholar, National Library of Indonesia, EBSCO, and PubMed are used as source of this literature review. Conclusion: Both of the sealer cause discoloration because of their composition such as zinc oxide and eugenol that caused continuous oxidation in ZOE sealer and bismuth oxide which interacts with dentin in MTA sealer. Application of MTA is recommended because of their minimal color alteration compared to ZOE sealer, and their excellent physical properties and biocompatibility

In-Vitro Effect of Effectively of G-Bond and Z-Prime Plus in Prevention of Fracture of Prefabricated Zirconia Posts Bonded to Root Canal Walls

Background and Aim: The purpose of this research was to examine the influence of Z-Prime Plus and G-Bond on zirconia posts fracture resistance affixed to the walls of root canals. Place of Study: Avicenna Medical College Lahore Study Duration: March 2021 to April 2022 Materials and Methods: In this in-vitro experimental study, the diameter and length of each of the 20 mandibular premolars used were identical. This assured that the study's findings were comparable. Once a cut was made at the cementoenamel junction (CEJ) to prepare the teeth for root canal therapy, the teeth were randomly assigned to one of two groups (n=11) with the same number of teeth in each group. In the experiment, a single tooth from each group was chosen at random to serve as the control. A post space of approximately 10 millimeters in length was established in the remaining teeth. The following process involved etching the intracanal dentin, followed by rinsing and drying the material. The technique involved filling the canal with Panavia F2 resin cement. After applying G-Bond and Z-Prime Plus to the zirconia posts in respectively, groups 1 and 2, the placement of post was done in the canals and subsequently cemented. The photo core resin composite material was utilized in the fabrication of the cores. The longitudinal axis of the teeth was compressed by a force application to the core of central fossa o at a crosshead speed of 0.5 millimeters per minute. This was accomplished with a crosshead speed of 0.5 mm/min. The load that caused the fracture was measured and documented. To analyze the data, a t-test was conducted, and a normal distribution was also taken into account. Result: The results indicated that the average fracture resistance of G-Bond was 1088.1±330 while the average fracture resistance of Z-Prime Plus was 898.4±369 however, the difference was not statistically significant (P=0.3). Practical Implication: The influence of Z-Prime Plus and G-Bond on zirconia posts fracture resistance affixed to the walls of root canals Conclusion: There was no significant difference between the fracture resistance of zirconia posts bound with G-Bond and Z-Prime Plus to root canal walls. In contrast, G-Bond is highly advised for usage in this application due to its decreased coefficient of variation (CV) and significantly increased fracture resistance. This makes it a great option for the current endeavor. Keywords: Primer; resin composite; shear bond strength; zirconia ceramic, G-Bond, Post and Core Technique, Z-Prime Plus

Endodontic tooth treatment with internal root resorption: case report

INTRODUCTION: Internal tooth resorption is characterized by the destruction of dentin in the root canal wall due to an imbalance of clastic cell activity resulting mainly from trauma. Thus, endodontic treatment is indicated with the aim of removing the etiology of resorption by using intracanal medication to combat possible infection and thus provide tissue repair. OBJECTIVE: The aim of this study is to investigate the treatment of root resorption by conventional endodontic therapy by identifying internal resorption and highlighting the steps of endodontic treatment. CASE REPORT: The methodology adopted was a clinical study in which we selected a female patient who required endodontic treatment of tooth 12 with pulp necrosis and resorption in the middle third of the root. Thus, the endodontic treatment was performed according to the technique, through instrumentation of the root canal followed by irrigation with sodium hypochlorite 6%. After instrumentation, the PUI (Ultrasonic Passive Irrigation) was performed followed by irrigation with 6% sodium hypochlorite and EDTA solution. The root canal was also dried and filled, allowing the respective tooth to be provisionally restored with glass ionomer so that it could later be permanently restored according to the indication of the material. Therefore, internal tooth resorption causes irreversible damage to the individual, such as tooth loss, thus altering the functioning of the stomatognathic system. Thus, endodontic treatment has great advantages in the treatment of teeth with internal tooth resorption since it promotes stagnation of the resorption process and tissue repair. CONCLUSIONS: Therefore, the treatment of internal tooth resorption requires close attention by the dental surgeon due to careful evaluation throughout the entire clinical case.

The resistance of the intracanal retention thickness with flowable short fiber reinforced composite (SFRC) materials towards fracture toughness

ABSTRACTIntroduction: Dental hard tissue problems were relatively high in Indonesia. If these problems were ignored, they would cause pulpal necrosis. The main treatment for this case was Root Canal Treatment (RCT). The selection of post-RCT treatment and suitable materials was important. One of the examples was short fiber reinforced composite (SFRC) which can be an option for intracanal retention treatment. This study aims to analyze the resistance of the intracanal retention thickness with flowable fiber reinforced composite materials toward fracture toughness. Methods: This research was using a correlative laboratory experimental method with a post-test group-only design. This study's samples were SFRC material inserted in 27 extracted mandibular first premolars with a length of 21 mm ± 2 mm and root canal walls width of 2 mm. All samples were given intracanal retention at a depth of 2 mm below the orifice and divided into 3 groups: intracanal retention with thickness of (A) 6 mm, (B) 5 mm, and (C) 4 mm. RCT was performed using the crown-down technique. The bonding agent was applied, and then light cured for 20 seconds. SFRC was applied according to the sample group and light cured for 20 seconds per 2 mm, followed by filling with composite resin. The sample was implanted in the dental stone 2 mm below the CEJ. The fracture toughness test was performed using UTM on the occlusal surface with a 0o tilt and crosshead of 1 mm/min. Results: The fracture toughness results of group A, B, and C are 735.44, 756.78, and 829 respectively. Statistical tests with one-way ANOVA showed no significant difference with p value = 0.412 (p &lt; 0.05). Conclusion: There is no difference in resistance of the intracanal retention thickness with flowable fiber reinforced composite materials towards fracture toughness.Keywords: post-RCT treatments, intracanal retentions, SFRC, fracture toughness

The push-out bond strength of three root canal materials used in primary teeth: In vitro study

The study aims to compare the bond strength of three primary tooth root canal filling materials to the root canal wall with a push-out test (Calplus, Diapaste, BIOfactor MTA). First, 30 primary central teeth were cut transversely using a water-cooled low-speed diamond saw vertical to the long axis to obtain 2 mm thick discs from the middle third of the roots. Next the materials used were placed on dentin discs and kept in an incubator for 1 week at 37°C and 100% humidity until the hardening mechanism of the root-canal sealer was completed. Finally, a vertical force was placed on each material from apical to coronal with a 0.75 mm diameter stainless steel cylindrical piston without contacting the root canal dentin. The data were analyzed using the SPSS 22.0 program and Mann-Whitney U test was used as a post hoc test. There was a statistically significant difference between the bonding values of different primary tooth root canal sealers to root canal dentin (p &amp;lt; 0.05). Among the maximum binding values, the lowest measurement was in Calplus (0.43 ± 0.28 MPa), and the highest measurement was in BIOfactor MTA (24.24 ± 17.78 MPa) (p &amp;lt; 0.05). BIOfactor MTA has a higher bonding value to root canal dentin than calcium hydroxide-based primary tooth canal sealers.

Cauterization of Narrow Root Canals Untouched by Instruments by High-Frequency Current.

The mechanical removal of bacteria is fundamental to the treatment of infected root canals, but complete sterilization of biofilms tends not to extend to uninstrumented areas. However, during electrical conduction to a root canal filled with a conductor, the higher impedance where the root canal is narrower generates Joule heat that may result in a large temperature increase and sterilization. The effect of a high-frequency electric current on the wall of a simulated narrow root canal was investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Simulated root canals, 0.1 mm in diameter, were prepared in dentine blocks. The root canal wall was treated with Plank-Rychlo solution for 5 min to create a decalcified layer. The simulated root canal was filled with either saline or NaClO, and 150 or 225 V at 520 kHz was applied for 0 s, 1 s, or 5 s. As the conduction time increased, and when the saline was replaced with NaClO, the proportion with a flat decalcified surface decreased, dentinal tubules and a lava-like morphology were significantly more evident on SEM (p < 0.01), and EDS showed significant decreases in carbon and oxygen and increases in calcium (p < 0.01). It was concluded that filling uninstrumented root canals with NaClO and using electrical conduction for 5 s could incinerate and eliminate the organic material of the root canal wall. The application of high-frequency electric current may lead to the cure of many cases of persistent apical periodontitis.

Clinical observation of autologous platelet rich fibrin assisted revascularization of mature permanent teeth

ObjectiveTo investigate the clinical observation of autologous platelet-rich fibrin (PRF) assisting the revascularization of mature permanent teeth.MethodsTwenty patients with mature permanent teeth were divided into experimental group and control group. The control group was treated with classic revascularization, and the experimental group was treated with PRF-assisted mature permanent tooth revascularization.ResultsAfter treatment, the total effective rate of the experimental group (100.00%) was higher than that of the control group (50.00%); the thickness of the root canal wall of the experimental group was higher than that of the control group, and the crown root length was lower than that of the control group; The bite degree, chewing function, color, overall aesthetic score, and satisfaction rate of the patients were higher, and the difference was statistically significant (P < 0.05).ConclusionAutologous PRF assists in revascularization of mature permanent teeth, which can achieve ideal results, and promote pulp regeneration.

Pushout Bond Strength of Root Fillings after Irrigation of Root Canals Utilizing Sodium Hypochlorite, Chlorhexidine, and Homeopathic Mother Tincture (Arnica Montana)

The pushout bond strength of root fillings at radicular dentin was investigated employing NaOCl, CHX, and homoeopathic mother tincture (Arnica montana) as an irrigant. Sixty human permanent single-rooted extracted teeth were decoronated. The root canals were instrumented using Pro taper universal rotary system (Dentsply Tulsa Dental; Tulsa, Oklahoma) and were prepared up to F3 apical size. The roots were then randomly divided into three groups according to irrigation solution (n = 20) according to the final irrigation regimen: Group I: 3 mL 5.25% NaOCl followed by 3 mL Saline (control); Group II: 3 mL Arnica montana (10%, w/v) followed by 3 mL Saline; Group III: 3 mL CHX followed by 3 mL Saline. The canals were dried using paper points. The canals were coated with AH Plus sealer (Dentsply DeTey, Konstaz, Germany) with the aid of a Lentulo spiral (Dentsply DeTey, Konstaz, Germany) and obturated with #F3 gutta-percha. Each root was then horizontally sliced into three slices, labelled coronal, middle, and apical, each measuring 2 mm thick. Furthermore, at a crosshead speed of 2 mm/min, the test was carried out using the universal testing apparatus. The 5.25% NaOCl significantly decreased the bond strength of AH Plus to dentin. Both CHX and Arnica montana were capable of reversing the compromised pushout of AH Plus to NaOCl-treated dentin. After using NaOCl as an irrigant, the danger of diminished binding capacity of AH Plus to root canal walls arises. Final irrigation with Arnica montana and CHX reduces this risk.

Effectiveness of Retreatment of Oval-Shaped Canals Filled With Warm Gutta-Percha: A Systematic Review

Oval-shaped canals with their isthmuses and inter-canal communications represent a challenge for secondary endodontic treatment. Different techniques have been proposed to enhance the filling removal during retreatment procedures of oval canals filled with warm gutta-percha techniques. The aim of this review article is to systematically summarize and analyze published in vitro studies over a ten-year period of time (2012-2022), evaluating the effectiveness of retreatment of oval-shaped canals filled with warm vertical compaction technique and/or carrier-based gutta-percha. A thorough search in PubMed - MEDLINE, The Cochrane Library and Science Direct databases and manual web search was performed. After the investigations were assessed by two reviewers. A total number of eleven articles out of 145 titles covered all eligibility criteria and were selected for further synthesis. All articles investigated the effectiveness of retreatment techniques in oval-shaped root canals filled with warm vertical compaction or/and carrier-based gutta-percha. According to the present review none of the currently described retreatment techniques resulted in completely clean of remnants root canal walls. Secondary endodontic treatment is still a difficult procedure and due to the complex anatomy of oval-shaped root canals, their retreatment represents even a bigger challenge and often requires additional cleaning procedures.

Impact of Endodontic Irrigant Activation on Smear Layer Removal and Surface Disintegration of Root Canal Dentine In Vitro.

The objective of this study was to compare the ability of different endodontic irrigation activation methods to enable irrigant penetration, remove the smear layer from root canal walls after preparation, and investigate surface effects on dentine. Root canals of 90 single-rooted teeth were prepared and irrigated with EDTA (17%) and sodium hypochlorite (5%), where both irrigants or sodium hypochlorite only were activated as follows: conventional needle irrigation, ultrasonic activation, sonic activation (EDDY), or laser-based activation (photon-induced photoacoustic streaming/PIPS). For the evaluation of irrigant penetration into dentinal tubules, methylene blue was injected and activated as well. Subsequently, teeth were sectioned horizontally, and dye penetration depths were measured. Alternating sections were split in halves and randomly selected for scanning electron microscopic analysis. Root canal dentine was assessed for smear layer removal and surface disintegration according to a defined scoring system. The data were analyzed statistically with nonparametric and chi-squared tests for whole teeth and separately for coronal, middle, and apical thirds. All the tested activation methods removed a thicker smear layer than needle irrigation only. Additional activation of EDTA improved penetration depths of the irrigants, but not the smear layer removal. Surface disintegration of root canal dentine was observed with the additional activation of EDTA and particularly after laser-based techniques. Additional activation of EDTA does not seem to offer any convincing advantages in terms of irrigant penetration or smear layer removal but disrupts the dentine surface. Especially laser-based activation resulted in undesirable destruction of root canal wall dentine.

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

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

Effects of Conservative Access and Apical Enlargement on Shaping and Dentin Preservation with Traditional and Modern Instruments: A Micro-computed Tomographic Study

IntroductionThis ex vivo study aimed to evaluate the shaping abilities and preservation of dentin with traditional and modern instruments after using sizes 25 and 40 in oval canals of mandibular incisors with conservative access. MethodThirty mandibular incisors with single straight oval canals were selected and assigned into 2 groups (n = 15) according to the instrument system used during preparation, Slim Shaper (SS) plus Apical Shaper (AS) and Protaper Gold (PG). The samples were subjected to micro-computed tomography before and after preparation with sizes 25 and 40. The shaping parameters evaluated included canal volume and surface area, amount of unprepared root canal walls, and reduction in pericervical dentin. ResultsCanal volume and surface area were significantly increased after enlargement with each instrument size (P < .01). The percentage of unprepared areas showed a significant intragroup decrease after using PG F2 and F4 or SS 3 and AS (P < .05). Intergroup comparison showed no significant differences. Pericervical dentin was reduced in all groups. The intragroup comparison only revealed a significant reduction (P < .01) between PG F2 and F4. In addition, a significant decrease in pericervical dentin (P < .05) was observed between PG F4 40/.06 and AS 40/.03. No significant differences were observed between PG F2 25/.08 and SS 3 25/.04. ConclusionIncreasing the instrumentation size from 25 to 40 significantly reduces the percentage of unprepared areas regardless of the system used. In addition, using a modern system with a regressive taper allows the maintenance of pericervical dentin without compromising shaping efficacy in the apical third of the mandibular incisors with oval canals and conservative access.