Effectiveness of rotatory and reciprocating movements in root canal filling material removal

Effect of treatment variables on apical extrusion of debris during root canal retreatment: A systematic review and meta-analysis of laboratory studies

Background

This study aimed to systematically and comprehensively review the effect of various treatment variables on apically extruded debris (AED) during non-surgical root canal retreatment (NSRCRT).

Methods

The study protocol is shared in the Open Science Framework database (https://osf.io/kjtdg/?view_only=17060180705745ec9dae9a01614f3880). An electronic search was conducted up to July 2022 to reveal related studies. Two reviewers critically assessed the studies for eligibility against inclusion and exclusion criteria and data extraction. Quantitative data synthesis was performed, and the risk of bias in the studies was also evaluated.

Results

Forty-six studies were included in the systematic review and 14 in the meta-analysis. Conflicting or limited evidence was found for the effect of sealer type, obturation technique, and solvent use. The manual instrumentation increased the amount of AED compared to rotary instrumentation during the removal of filling materials (P<0.001). There was no significant difference in the amount of AED between the use of rotary and reciprocating files during the removal of filling materials (P=0.181).

Conclusion

Rotary instruments can be recommended instead of manual instruments during the removal of filling materials to control the amount of AED. Further studies with a low risk of bias are needed to clarify the effect of other treatment variables on AED during NSRCRT.

Influence of Apical Diameter on Filling Material Extrusion during Retreatment - A Micro-CT and CBCT evaluation

AIM

To investigate whether foraminal widening performed at primary treatment has an effect on the amount of apically extruded obturator material during retreatment and to evaluate the sensitivity of cone beam computed tomography (CBCT) in detecting extruded obturator material.

METHODS

Forty palatal roots of maxillary molars were selected based on micro-CT and divided into two groups (n=20): with foraminal widening (WE) and without foraminal widening (NE). To standardize the apical foramen, all specimens were instrumented to the foramen using the Protaper Next system, up to instrument X3. The WE group was instrumented to the foramen up to instrument X5, and the NE group was instrumented 1 mm lower. The canals were obturated 1 mm below the apical foramen with gutta-percha and AH Plus and stored for 7 days at 37 °C and 95% humidity. Roots were fixed in microtubes filled with 1.5% agar gel. The obturation material was removed with Reciproc R50. Scans of the teeth and agar were performed using micro-CT and CBCT. Comparison between groups and between methods was performed using Mann-Withney test (p ≤0.05).

RESULTS

No statistical difference was found when comparing the extruded material between groups using micro-CT (p = 0.589) or CBCT (p = 0.953). CBCT measured a greater volume of extruded material than micro- CT (p = 0.0004).

CONCLUSION

Foraminal widening had no effect on the extrusion of filling material during retreatment. The CBCT favored the evaluation of apically extruded filling material.

An Appraisal on Newer Endodontic File Systems: A Narrative Review

AIM

This narrative review aims to explore and elicit the newer endodontic file systems used for root canal treatments.

BACKGROUND

The primary goals of endodontic therapy continue to be the mechanical enlargement and shaping of the intricate endodontic root canal systems to aid in disinfection. Nowadays endodontists have access to a wide range of endodontic file systems for root canal preparations with various design characteristics and benefits.

REVIEW RESULTS

ProTaper Ultimate (PTU) files' tip have a triangular convex cross-section, an offset mass of rotating design, a maximum flute diameter of 1.0 mm, and are constructed of gold wire, hence, commonly applied in conditions with restricted accessibility or an extremely curved canal. TruNatomyhas advantages over other cutting-edge file systems like maximum flute diameter of the corona, reduced distance between active cutting flutes, and shorter handles in comparison to SX instruments. In comparison to PTU files, ProTaper Gold (PTG) files are noticeably more elastic and fatigue-resistant. Compared to files in the F1-F3 range, size S1 and S2 files have a significantly longer fatigue life. MicroMega One RECI is more resistant to cyclic fatigue because of its heat treatment and reciprocating action and the C-wire heat treatment of the former gives it flexibility and controlled memory, enabling the prebending of the file. The RECIPROC blue demonstrated enhanced flexibility, increased fatigue resistance, and lower microhardness while maintaining the same surface qualities.

CONCLUSION

As per the necessity and requirement on case to case basis, every endodontic file system has advantages and disadvantages as mentioned in this narrative review. According to the need, an endodontist can select the file system which is required specifically. Although several studies are comparing these various systems in the literature, this narrative review aims to give the clinician a summary of some recently launched endodontic rotary file systems available in the market and their clinical uses.

CLINICAL SIGNIFICANCE

As per the priority and need of the case, whether removal and extrusion of debris, reduction of micro-organisms, keeping canal anatomy, and cutting efficiency, a specific required file system can be utilized.

Critical analysis of research methods and experimental models to study removal of root filling materials

Despite enjoying high favourable outcome rates, root canal treatment is not always successful. Root canal retreatment is a widely practised option for managing a non-healing root treated tooth. A basic distinction between retreatment and initial treatment is the requirement to remove the existing root filling material occupying the root canal space. Only then, can the technical deficiencies and possible causes of failure be addressed. Hence, the successful removal of the root filling material is critical to achieving the objectives of retreatment. Many different materials and techniques have been used for root canal filling, which have been documented in a plethora of studies; these are mainly laboratory studies investigating the removal of root filling materials. To help guide future research, which may then better inform clinical practice in relation to retreatment procedures, the focus of this narrative review is on the research methods and experimental models employed to study the removal of root filling materials. The current available literature demonstrates great variation in the research methodologies used to study the removal of root filling material, including direct visualization by splitting tooth samples or clearing, three-dimensional radiographic imaging including using microcomputed tomography or cone-beam computed tomography, and a combination of these techniques. Depending on the research method employed, variation also exists in quantification of root filling material removal; these include measurements of surface area, volume or weight, and criteria-based (semi-quantitative) assessment. Experimental models, using human teeth or resin models, differ with respect to standardization techniques and replication of the clinical scenario including initial sample preparation, canal filling, allocation and technical aspects of retreatment procedures. Future models should replicate, as closely as possible, the clinical scenario. Currently, microcomputed tomography provides a highly detailed, non-invasive and non-destructive method of objectively assessing and quantifying root filling removal.

Efficacy of an arrow-shaped ultrasonic tip for the removal of residual root canal filling materials

This study aimed to evaluate the efficacy of supplementary methods to remove the remaining root filling material from root canals. Twenty mandibular single-rooted teeth were instrumented with Reciproc 25/0.08 and filled with gutta-percha and AH-Plus sealer, followed by a micro-CT scanning. The retreatment procedures were performed, the samples were rescanned and divided into two groups (n = 10) according to the supplementary method: XP-endo Finisher R and Clearsonic tip. The samples were rescanned and the volume of remaining root filling material was quantified. Data were analysed statistically (P < 0.05). The amount of filling material removed after supplementary methods was higher compared with retreatment procedure (P < 0.05). XP-endo Finisher R promoted a greater percentage of filling materials reduction in the entire root canal and apical third compared with Clearsonic tip (P < 0.05). Supplementary methods were effective in the reduction of root filling materials. XP-endo Finisher R removed more root filling material than Clearsonic tip.

Efficacy of Removing Thermafil and GuttaCore from Straight Root Canal Systems Using a Novel Non-Surgical Root Canal Re-Treatment System: A Micro-Computed Tomography Analysis

The present study aims to evaluate the effectiveness of an XP-endo non-surgical root canal re-treatment system in removing both GuttaCore and Thermafil gutta-percha carrier-based root canal filling materials from straight root canal systems using micro-computed tomography (micro-CT) analysis. The study was performed on 20 single-rooted upper teeth, which were randomly allocated into the following study groups: Group A, Thermafil and AH Plus sealer (n = 10); Group B, GuttaCore and AH Plus sealer (n = 10). Before and after the non-surgical root canal re-treatment procedure, the samples were submitted for a micro-CT analysis. The volume of the root canal filling material (mm³), the volume of the remaining root canal filling material (mm³) and the time (minutes) needed to remove the root canal filling material were also recorded. Student's t-test was used to analyze the results. No statistically significant differences were found between the volume of the remaining root canal filling material in the GuttaCore and Thermafil root canal filling systems at the coronal third (p = 0.782), middle third (p = 0.838) or apical third (p = 0.882) of the straight root canal systems; however, the GuttaCore required a statistically significant (p = 0.037) shorter amount of time (4.72 ± 0.76 min) to be removed than the Thermafil carrier-based root canal filling material (5.92 ± 1.42 min). The XP-endo Finisher non-surgical endodontic re-treatment system removes both GuttaCore and Thermafil gutta-percha carrier-based root canal filling materials from straight root canal systems, although removal of the GuttaCore gutta-percha carrier-based root canal filling material required less time.

The Efficacy of Rotary, Reciprocating, and Combined Non-Surgical Endodontic Retreatment Techniques in Removing a Carrier-Based Root Canal Filling Material from Straight Root Canal Systems: A Micro-Computed Tomography Analysis

The aim of this study is to analyze and compare the efficacy of three non-surgical endodontic retreatment techniques in removing a carrier-based root canal filling material from straight root canal systems. The study was performed on 99 single-rooted extracted teeth using the ProTaper Gold endodontic rotary system up to the F2 file (Dentsply Maillefer, Baillagues, Switzerland), which were sealed with GuttaCore (Dentsply Maillefer, Ballaigues, Switzerland) and AH plus epoxy resin sealer (Dentsply DeTrey, Konstanz, Germany) and randomly assigned to the following non-surgical retreatment techniques: ProTaper Retreatment endodontic rotary instruments (D1–D3 files, Dentsply Maillefer, Ballaigues, Switzerland; n = 33, PTR), Reciproc Blue endodontic reciprocating instrument (R50, VDW, Munich, Germany; n = 33, RCB50), and a combined root canal retreatment technique between Gates-Glidden drills (sizes #3 and #2, Dentsply Maillefer, Ballaigues, Switzerland) and Hedstrom files (file size 35, 30, and 25, Dentsply Maillefer, Ballaigues, Switzerland; n = 33; H-GG). All of the teeth were submitted twice to a micro-computed tomography (micro-CT) scan, before and after non-surgical endodontic retreatment procedures. The volume of root canal filling material (mm³), volume of remaining root canal filling material (mm³), non-surgical endodontic retreatment working time (min), proportion of remaining root canal filling material (%), and efficacy of root canal filling material removal between the non-surgical endodontic retreatment techniques were analyzed using ANOVA one-way statistical analysis. Statistically significant differences were observed between the proportions of remaining root canal filling material of PTR and H-GG (p = 0.018), between the non-surgical endodontic retreatment working times (min; p < 0.001), and between the efficacies of root canal filling material removal by the non-surgical endodontic retreatment techniques (p = 0.009). However, the non-surgical endodontic retreatment systems allow for similar carrier-based root canal filling material removal.

Apical Transportation and Centering Ability After Root Canal Filling Removal Using Reciprocating and Continuous Rotary Systems: A CBCT Study

OBJECTIVE

To evaluate the apical transportation and centering ability promoted by reciprocating and continuous rotary systems after root canal filling removal.

MATERIALS AND METHODS

After obturation, 40 mesial root canals of mandibular molars were distributed into four groups (n = 20) for filling material removal: PTU group-F2 instrument (25.08) of ProTaper Universal system; R25 group-R25 instrument (25.08) of Reciproc system; X2 group-X2 instrument (25.06) of ProTaper Next system and X3 group-X2 instrument (25.06) of ProTaper Next system, followed by X3 instrument (30.07). Cone-beam computed tomographic analysis was performed before and after filling material removal for acquisition of apical images. Apical transportation (AT) and its direction, and centering ability (CA), were assessed using the equations AT = (X1-X2)-(Y1-Y2) and CA = (X1-X2/Y1-Y2 or Y1-Y2/X1-X2), respectively. Data were submitted to the nonparametric Kruskal-Wallis and Dunn multiple comparison tests (p < 0.05) for statistical analysis.

RESULTS

There was no statistically significant difference among groups for AT (p > 0.05), with a tendency toward transportation in the distal direction. Also, there was no statistically significant difference among groups regarding CA (p > 0.05).

CONCLUSIONS

The different systems, including ProTaper Next, caused AT within the acceptable clinical limit after filling removal. In addition, none of the tested systems presented adequate CA.

Factors affecting the periapical healing process of endodontically treated teeth

Tissue repair is an essential process that reestablishes tissue integrity and regular function. Nevertheless, different therapeutic factors and clinical conditions may interfere in this process of periapical healing. This review aims to discuss the important therapeutic factors associated with the clinical protocol used during root canal treatment and to highlight the systemic conditions associated with the periapical healing process of endodontically treated teeth. The antibacterial strategies indicated in the conventional treatment of an inflamed and infected pulp and the modulation of the host's immune response may assist in tissue repair, if wound healing has been hindered by infection. Systemic conditions, such as diabetes mellitus and hypertension, can also inhibit wound healing. The success of root canal treatment is affected by the correct choice of clinical protocol. These factors are dependent on the sanitization process (instrumentation, irrigant solution, irrigating strategies, and intracanal dressing), the apical limit of the root canal preparation and obturation, and the quality of the sealer. The challenges affecting the healing process of endodontically treated teeth include control of the inflammation of pulp or infectious processes and simultaneous neutralization of unpredictable provocations to the periapical tissue. Along with these factors, one must understand the local and general clinical conditions (systemic health of the patient) that affect the outcome of root canal treatment prediction.

Global oral inequalities in HIV infection

Analysis of the prevalence and incidence of HIV infection globally reveal striking variances with regard to continent, country, region and gender. Of the global total of 33 million people infected with HIV, approximately 65% are in sub-Saharan African countries and 15% in South and South-East Asia with the remaining 20% spread over the rest of the world. As a percentage of the population, the Caribbean at 1.1% is second only to sub-Saharan Africa (5.5%). The majority of the world's HIV is in women. Deaths from HIV are twenty-fold greater in Africa than in Europe or the USA. Individual countries in sub-Saharan Africa show huge variances in the HIV+ prevalence with most West African countries having a rate of less than 2% whilst southern African countries including Swaziland and Botswana have rates of around 25%. Environment, education and social habits all contribute to the HIV infection rates. Similar variations between countries are seen in SE Asia with Cambodia and Papua New Guinea having rates three times greater than Pakistan. One of the most striking examples of inequality is in life years added to HIV populations as a result of antiretroviral therapy. UN AIDS figures over 1996-2008 suggest an average of 2.88 added years in the USA and Europe, but only 0.1 in sub-Saharan Africa, a thirty-fold difference largely due to accessibility to ART. ART leads to a reduction in oral lesions but it is estimated that some 10 million HIV+ subjects do not have access to oral care. Thus, inequalities exist both for HIV infection and for the associated oral lesions, mainly related to ART access. HIV infection and oral mucosal lesions both appear to be related to general social determinants of health. Oral HCW must be part of mainstream healthcare teams to address these inequalities.

Filling Material Removal with Reciprocating and Rotary Systems Associated with Passive Ultrasonic Irrigation

Objective:

The purpose of this ex vivo study was to evaluate the filling material removal ability, and the time required to perform this procedure, of reciprocating and conventional rotary systems when associated with passive ultrasonic irrigation.

Methods:

The palatal roots of 40 maxillary molars were submitted to root canal preparation and filling. The desobturation of root canals was initially performed with Largo burs in the coronal portion (4 mm) to drill the gutta-percha and to facilitate the action of the instruments used then. Next, the palatal roots were randomly distributed (n=10) according to the systems and irrigation protocols used for filling material removal: ProTaper universal retreatment (PTR), PTR+passive ultrasonic irrigation (PUI) (PTR+PUI), Reciproc system (RS), and RS+PUI. Passive ultrasonic activation was performed in the root canals completely filled with 2.5% sodium hypochlorite solution using a smooth and straight ultrasonic tip, coupled to a low-power (20%) ultrasonic device for 1 min (3 cycles of 20 s). After retreatment, the roots were longitudinally sectioned to the remaining filling material quantification using an operating microscope. Environmental scanning electron microscopy (ESEM) micrographs at 97, 105, and 250 X magnifications were also taken to evaluate the quantity of filling material present at the apical portion of the palatal roots.

Results:

The RS group presented greater quantity of filling material attached to the root canal walls than the other groups (P>0.05). PTR+PUI and RS+PUI groups were statistically similar (P>0.05). Reinstrumentation of root canals using RS was faster than PTR, irrespective of the irrigation protocol used (P>0.05).

Conclusion:

The association between PUI and the different systems for reinstrumentation yielded greSater filling material removal. The reciprocating system was faster.

A comparative evaluation of two rotary Ni-Ti instruments in the removal of gutta-percha during retreatment

AIM

The purpose of this study is to achieve an effective method to remove root canal filling material from the root canal system. The study, thus, aims to evaluate the efficacy of the cleaning ability of two different rotary Ni-Ti systems; ProTaper Retreatment files and RaCe System compared to hand instrumentation with Hedstrom files for the removal of gutta-percha during retreatment.

MATERIALS AND METHODS

Thirty mandibular premolars with one single straight canal were decoronated and instrumented with ProTaper files and filled with thermoplastic gutta-percha. After 30 days, the samples were divided into three groups and gutta-percha was removed with the test instruments. The postoperative radiographs were evaluated with known criteria by dividing the root into cervical third, middle third, and apical third. The results were tabulated and Statistical Package for Social Sciences Software (IBM Corporation) was used for analysis.

RESULTS

The mean deviation of the results were first calculated and then t-test and analysis of variance test (two-tailed P value) were evaluated for establishing significant differences. The rotary instruments were effective in removing the gutta-percha from the canals. Therefore, significant difference was observed between the efficacies of the two rotary systems used. The rotary instruments showed effective gutta-percha removal in the cervical and middle one third. (P > 0.05). However, apical debridement was effective with Hedstrom files.

CONCLUSION

The study concluded the use of both rotary and hand instrumentation for effective removal of gutta-percha for retreatment.

Micro-Computed Tomography Study of Filling Material Removal from Oval-shaped Canals by Using Rotary, Reciprocating, and Adaptive Motion Systems

INTRODUCTION

This study evaluated filling material removal from distal oval-shaped canals of mandibular molars with rotary, reciprocating, and adaptive motion systems by using micro-computed tomography.

METHODS

After cone-beam computed tomography scanning, 21 teeth were selected, prepared up to a size 40 file, root filled, and divided into 3 groups (n = 7) according to the filling material removal technique: group PTUR, ProTaper Universal Retreatment combined with ProTaper Universal F2, F3, F4, and F5 files; group RP, Reciproc R50 file; and group TFA: TF Adaptive 50.04 files. The specimens were scanned preoperatively and postoperatively to assess filling material removal by using micro-computed tomography imaging, and the percent volume of residual filling material was calculated.

RESULTS

The statistical analysis showed the lowest percent volume of residual filling material at the coronal third in all groups (P < .05). There was no significant difference among the systems in the coronal third (P > .05). In the middle third, group TFA (31.2 ± 10.1) showed lower volume of residual filling material than group RP (52.4 ± 14.1) (P < .05). In the apical third, groups TFA (44.8 ± 20.6) and PTUR (48.6 ± 16.8) presented a lower percent volume of filling material than group RP (70.6 ± 7.2) (P < .05), as confirmed by the qualitative analysis.

CONCLUSIONS

The use of the adaptive motion increased the amount of root filling removed in the middle and apical thirds compared with the reciprocating motion. However, no technique was able to completely remove the filling material from the canals.

Efficacy of Combined Use of Different Nickel-Titanium Files on Removing Root Canal Filling Materials

INTRODUCTION

The aim of this study was to estimate the remaining amount of residual filling materials in root canals after retreatment using ProTaper Universal Retreatment (PTUR) files (Dentsply Maillefer, Ballaigues, Switzerland) alone or with the additional use of the Self-Adjusting File (SAF; ReDent-Nova, Ra'anana, Israel), Reciproc (VDW, Munich, Germany), or Hedström-files (H-file; VDW, Antaeos, Munich, Germany) with volumetric estimation using the stereologic method via cone-beam computed tomographic images.

METHODS

Forty-eight mandibular premolars with single canals were used. The canals were instrumented with ProTaper rotary instruments up to F4 and filled with gutta-percha and AH26 sealer (Dentsply De Trey, Johnson City, TN). All the samples were placed into the silicone models. Samples were scanned with cone-beam computed tomographic imaging and assigned into 4 groups (n = 12) according to retreatment files: the PTUR system group, the PTUR system plus SAF group, the PTUR system plus Reciproc group, and the PTUR system plus H-file group. The specimens were rescanned after retreatment procedures, and the volume estimations of the remaining filling materials were performed using the stereologic method. Data were analyzed using Kruskal-Wallis and Dunn tests.

RESULTS

There was no significant difference among the groups regarding mean percentage volumes of the filling materials before retreatment procedures (P > .05). None of the retreatment procedures provided complete removal of the filling materials. The additional use of the SAF did not significantly improve the removal of filling materials when compared with the PTUR system alone (P > .05). However, the additional use of Reciproc or hand H-files significantly improved the removal of filling materials when compared with the PTUR system alone (P < .05).

CONCLUSIONS

The additional use of files with different motion kinetics improved the removal of root canal fillings; however, none of the systems completely removed the root canal filling material from the root canals.

Micro-CT Evaluation of Root Filling Removal after Three Stages of Retreatment Procedure

The aim of this study was to quantify the residual filling material after filling removal, re-preparation with rotary or reciprocating files and passive ultrasonic irrigation (PUI). Twenty maxillary molars were prepared using ProTaper instruments up to F1. The teeth were filled with AH Plus and ProTaper gutta-percha points using the single-cone technique. Thereafter, the specimens were scanned using a micro-computed tomography system (Micro-CT #1). Then, the root canal filling was removed using ProTaper Retreatment files, and a new scan was performed (Micro-CT #2). The specimens were divided into two groups according to the instrument used for re-preparation: ProTaper rotary or WaveOne reciprocating files (Micro-CT #3). Finally, PUI was performed, and a new micro-CT scan was performed (Micro-CT #4). Intragroup and intergroup analyses were performed using Friedman and Dunn's post hoc test and the Kruskal-Wallis and Dunn post hoc tests, respectively. Palatal canal presented the highest volume of residual filling material in all stages of endodontic retreatment (p<0.05). The main reduction of filling volume was achieved after using ProTaper Retreament (p<0.05). The amount of remaining filling material after using ProTaper Retreatment was similar to that achieved with rotary and reciprocating files and after PUI (p>0.05). Rotary and reciprocating files achieved similar removal of the root canal filling (p>0.05). The greatest reduction in filling material was achieved after using ProTaper Retreatment files. Rotary and reciprocating instruments and PUI did not improve the removal of root canal filling materials.

Efficacy of Reciproc(®) and Profile(®) Instruments in the Removal of Gutta-Percha from Straight and Curved Root Canals ex Vivo

Objectives

To compare the efficacy of Reciproc^® (VDW GmbH) and ProFile^® (Dentsply Maillefer) instruments at removing gutta-percha from straight and curved root canals ex vivo filled using the cold lateral condensation and GuttaMaster^® (VDW GmbH) techniques.

Material and Methods

Forty mesial roots of mandibular molars with two curved canals and 80 single-rooted teeth with straight root canals, a total of 160 root canals, were randomly assigned to eight groups (canals per group = 20) according to filling technique, retreatment instrument and root canal curvature as follows: Group I, cold lateral condensation/ProFile^®/straight; Group II, cold lateral condensation/ProFile^®/curved; Group III, cold lateral condensation/Reciproc^®/straight; Group IV, cold lateral condensation/Reciproc^®/curved; Group V, GuttaMaster^®/ProFile^®/straight; Group VI, GuttaMaster^®/ProFile^®/curved; Group VII, GuttaMaster^®/Reciproc^®/straight; and Group VIII, GuttaMaster^®/Reciproc^®/curved. The following data were recorded: procedural errors, retreatment duration and canal wall cleanliness. Means and standard deviations were calculated and analysed using the Kruskal-Wallis test, one-way analysis of variance and Tukey’s test (P < 0.05).

Results

Reciproc^® instruments were significantly faster than ProFile^® instruments at removing GuttaMaster^® from both straight (P = 0.0001) and curved (P = 0.0003) root canals. Reciproc^® were statistically more effective than ProFile^® instruments in removing GuttaMaster^® from straight root canals (P = 0.021). Regardless of filling technique or retreatment instrument, gutta-percha was removed more rapidly from curved than from straight root canals (P = 0.0001).

Conclusions

Neither system completely removed filling material from the root canals. Compared with ProFile^® instruments, Reciproc^® instruments removed GuttaMaster^® filling material from straight and curved root canals more rapidly.