A comparison of three gutta-percha obturation techniques to replicate canal irregularities

A comparison of radiographically determined periapical healing and tooth survival outcomes of root canal (re)treatment performed in two care pathways within the United Kingdom Armed Forces

AIMS

To compare radiographic periapical healing and tooth survival outcomes of root canal (re)treatment performed within two care pathways (Routine Dental Care and Referred Treatment Pathway), in the United Kingdom Armed Forces (UKAF), and determine the effects of endodontic complexity on outcomes.

METHODOLOGY

This retrospective cohort study included 1466 teeth in 1252 personnel who received root canal (re)treatment between 2015 and 2020. General Dental Practitioners treated 661 teeth (573 patients) (Routine cohort), whilst Dentists with a Special Interest treated 805 teeth (678 patients) (Referred cohort). The latter group were graduates of an MSc programme in Endodontics with 4-8 years of postgraduation experience. Case complexity was retrospectively determined for each tooth using the endodontic component of Restorative Index of Treatment Need (RIOTN) guidelines. Periapical healing was determined using loose radiographic criteria. The data were analysed using chi-square tests, univariate logistic regression and Cox proportional hazards models.

RESULTS

A significantly (p < 0.0001) larger proportion of cases of low complexity had undergone root canal treatment within the Routine versus Referred cohort. The odds of periapical healing was significantly higher within the Referred versus Routine cohort, regardless of analyses using pooled (OR = 1.17; 95% CI: 1.11, 1.22) or moderate complexity (OR = 4.71; 95% CI: 2.73, 8.11) data. Within the Routine cohort, anterior teeth had higher odds of periapical healing than posterior teeth (OR = 1.13; 95% CI: 1.04, 1.22). The 60-month cumulative tooth survival was lower (p = 0.03) in the Routine (90.5%) than the Referred (96.0%) cohort. Within the Routine cohort, the hazard of tooth loss was higher amongst posterior teeth (HR = 4.03; 95% CI: 1.92, 8.45) but lower if posterior teeth had cast restorations (HR = 0.36; 95% CI: 0.19, 0.70). For the Referred cohort, posterior teeth restored with cast restoration (vs not) had significantly lower risk of tooth loss (HR = 0.21; 95% CI: 0.08, 0.55).

CONCLUSIONS

For UKAF patients, root canal (re)treatment provided within the Referred pathway was significantly more likely to achieve periapical healing and better tooth survival than those provided within the Routine pathway. Posterior teeth restored with an indirect restoration had a higher proportion of tooth survival. This study supported the utility of the endodontic component of RIOTN for assessing case complexity.

The effect of an additional application of sealer prior to backfilling in the Continuous Wave of Condensation technique

An additional sealer application was investigated prior to backfilling with the Continuous Wave of Condensation (CWC). 105 Palatal roots were sectioned and prepared to a file size 40, 0.06 taper with Vortex Blue® files. Groups A, B and C had a single sealer application before while groups D, E and F, received a second application of dyed sealer prior to backfilling. Roots were sectioned at 2,3,4,6,7 and 8 mm from the root apex. The percentage of sealer and dentinal tubular penetration depth was calculated at each level. At each ascending level, the sealer percentage decreased for each experimental group while the number of outer third penetration depths increased when all groups were combined. An additional sealer application prior to backfilling had minimal effect on the percentage of sealer or outer third penetration depths and can be considered a clinical preference rather than an imperative step with the CWC technique.

Evaluation of Different Root Canal Obturation Techniques in Internal Root Resorption of Three-Dimensional Printed Teeth Manufactured Using Computer Software

The objective of this study was to evaluate and compare the filling ability of various root canal obturation techniques on the internal root resorption (IRR) cavities of replicated tooth samples manufactured using computer software and a three-dimensional (3D) printer. Orthographic images and root structures of a healthy upper maxilla central incisor in determined volumes and sizes were drawn as a prototype with the aid of computer software. Using the same software, an IRR defect was also modeled. These two images were then transferred to the AutoDesk Fusion 360 3D modeling program (AutoDesk, San Rafael, CA) for meshing. Afterward, the tooth model was transferred to a 3D modeling and prototyping program (RhinoCeros 3D; Robert McNells & Assoc., New York) and printed on a 3D printer. Eighty replicas with IRR were manufactured and divided into four groups (n = 20 per group) according to the obturating techniques as follows: Group 1: Cold lateral compaction (CLC), Group 2: Core Carrier System (GuttaCore), Group 3: Injectable Cold Filling (GuttaFlow® BioSeal), and Group 4: Continuous Wave Obturation System (Elements Free). After root canal filling, replicas were scanned with a high-resolution micro-computed tomography system (SkyScan 1172; Bruker-microCT, Kontich, Belgium), data regarding voids (unobturated areas) inside the IRR defects were statistically analyzed using nonparametric Kruskal-Wallis tests. A pairwise comparison between the tested groups showed that Groups 3 and 4 had significantly fewer voids compared with Groups 1 and 2 in IRR defects (p < 0.05). Group 1/Group 2 and Group 3/Group 4 had similar results in terms of voids and there were no statistically significant differences (p > 0.05). The injectable cold filling system (GuttaFlow BioSeal) and the injectable continuous wave obturation system (Elements Free) successfully obturated the pathological IRR irregularities when compared with CLC and core carrier (GuttaCore) systems.

Complete Obturation-Cold Lateral Condensation vs. Thermoplastic Techniques: A Systematic Review of Micro-CT Studies

To prevent re-infection and provide a hermetic seal of the root canal system, an endodontist must aim to produce a void-free obturation. This review aimed to compare the completeness of root canal obturation between the two most prevalent methods-cold lateral condensation and warm gutta-percha techniques-using micro-CT (PROSPERO reg no. 249815).

MATERIALS AND METHODS

A search of Scopus, Embase, PubMed (Medline via PubMed), and Web of Science databases was done without any time restriction according to the PRISMA protocol. Articles that compared both techniques and were published in English were included. Data was extracted and the risk of bias was assessed using an adapted tool based on previous studies.

RESULTS

A total of 141 studies were identified by the search. Following the screening and selection of articles, 9 studies were included for review. Data was extracted manually and tabulated. Most studies had a moderate risk of bias. None determined operator skill in both methods before comparison. The data extracted from the included studies suggests that both techniques produce voids in the obturation. The thermoplasticized gutta-percha techniques may result in fewer voids compared to cold lateral condensation.

CONCLUSION

Considering the limitations of the included studies, it was concluded that neither technique could completely obturate the root canal. Thermoplasticized gutta-percha techniques showed better outcomes despite a possible learning bias in favor of cold lateral condensation. Establishing operator skills before comparison may help reduce this bias.

Micro-CT Evaluation of Four Root Canal Obturation Techniques

PURPOSE

The aim of this in vitro study was to evaluate the quality of four root canal obturation techniques using microcomputed tomography (micro-CT).

MATERIALS AND METHODS

A total of 36 mandibular first premolars with mostly round canals were decoronated, then instrumented up to a size F3 rotary file, and dressed with an epoxy resin-based sealer. Subsequently, they were divided into 4 different groups (n = 9) based on the method of obturation: lateral condensation using 0.02 tapered master cone (LC2), lateral condensation using 0.04 tapered master cone (LC4), matched single-cone technique (MS), and matched single cone-mediated ultrasonic activation (MSUA). All the teeth were scanned using micro-CT (resolution of 19 μm), and the percentage volume of voids was calculated. One-way analysis of variance and Tukey test were used to analyze the data (α = 0.05).

RESULTS

The total percentage volume of voids was significantly lower in the MSUA group compared to all other groups (P < 0.05). The total percentage volume of voids was significantly lower in the MS group compared to the LC4 (P < 0.001) and LC2 (P < 0.001) groups. However, there was no significant difference between the LC2 and LC4 groups (P < 0.65).

CONCLUSIONS

MSUA, significantly, showed the least root canal filling voids amongst all the obturation techniques studied. MSUA can be considered an effective method for the filling of the round root canals. In general, lateral condensation using either 0.02 or 0.04 tapered master cones had significantly the highest volume percentage of voids amongst the experimental groups.

Filling quality of several obturation techniques in the presence of apically separated instruments: A Micro-CT study

Separated root canal instruments may affect the quality of root canal obturation and hence the survival of endodontically treated teeth. Obturation techniques may influence filling-quality. The aim was to evaluate the obturation quality of teeth filled with different obturation techniques in the presence of apically separated instruments using micro-computed tomography (μ-CT). Notched ProTaper F2 rotary-files were separated in the apical third of 36-human mandibular incisors with single root/canal and mature apex. Samples were filled by an endodontist according to one of the following obturation techniques (n = 12): cold lateral-compaction (CLC), single-cone (SC) and thermoplastic injection (TI). Samples were scanned by the Skyscan 1,274® μ-CT device after 1-week at 37°C in 100% humidity. Images of the sections were evaluated with CTan software in terms of total-volume and volume percentage of the filling materials and voids between coronal end of the separated instrument and gutta-percha/sealer filled void-free sections. Data was analyzed using Kruskal-Wallis and Mann Whitney-U tests with a significance level of 5%. Kruskal-Wallis revealed differences among groups (p < 0.05).Pairwise comparisons revealed that less volume of voids were measured in SC (0.02 ± 0.03 mm³ ) compared to CLC (0.15 ± 0.16 mm³ ) and TI (0.18 ± 0.24 mm³ ) (p < 0.05); while TI was statistically similar with CLC (p > 0.05). Percentages of volumes of voids and filling materials were as follows for SC, CLC and TI, respectively: 8.88 ± 18.52% and 24.45 ± 38.40%, 46.92 ± 33.53% and 53.07 ± 33.53%, 40.54 ± 33.85% and 42.79 ± 34.45%. The obturation technique may have a significant impact on the volume of voids in the presence of a separated file. No obturation technique produced a void-free root canal filling.

Comparative apical sealing evaluation of two bioceramic endodontic sealers

AIM

The current study aims to evaluate, using scanning electronic microscopy, the sealing ability of two bioceramic endodontic sealers, one consecrated and one experimental.

METHODS

Twenty monoradicular teeth were included in the study. The teeth were endodontically prepared at the working length. The shaping and cleaning involved the use of chelating gel MM EDTA 19% and continuous irrigation with sodium hypochlorite 2.5%. The radicular filling was performed using gutta-percha in association with a sealer. Ten teeth were filled with consecrated endodontic filling material and the others ten with the experimental bioceramic based sealer.

RESULTS

The evaluation of the sealers using SEM analysis allowed the identification and the measurement of gaps on the radicular dentin/sealer interface and the degree of apical sealing ability. No significant statistical difference was observed between the gap dimensions in the three areas for the tested bioceramic materials (p<0.005). In the apical region a homogenous layer with extensions intersecting the hybrid layer was observed when the experimental bioceramic sealer was used. In case of teeth filled with commercial sealer, peripheral hybrid extended areas were identified.

CONCLUSIONS

The two bioceramic sealers presented similar apical sealing. Gaps were identified in both sealers but also the presence of hybrid layer was identified.

Comparing the Ability of Different Materials and Techniques in Filling Artificial Internal Resorption Cavities

Objective

This ex vivo study aims to investigate the root filling quality of warm vertical technique, single-cone technique with GuttaFlow2, Endoseal MTA and EndoSequence BC sealer as a sealer in artificial internal resorption cavity.

Methods

For this study, 40 human single-root teeth were selected. After root preparation, the roots were horizontally sectioned 7 mm from the apex. The hemisphere cavities were created on both sides, and then they were re-approximated. According to filling methods and materials, the samples were randomly as-signed to four experimental groups: I: warm vertical compaction technique (WVC), II: single-cone technique with GuttaFlow2 (GF), III: single-cone technique with Endoseal MTA sealer (EM), IV: single-cone technique with EndoSequence BC sealer (ES). Filled roots were radiographed in buccolingual and mesiodistal views to check the obturation, and stored in humid environment at the room temperature for 7 days. Each tooth was sectioned 7 mm from the root apex at the level of the previous cut, and it was then photographed un-der stereomicroscope. The photographs and radiographs of all samples were imported to an image-analysis software to calculate the percentage of sealer, gutta-percha, and voids. The results were statistically analyzed using one-way ANOVA and Kruskal-Wallis Dunn's tests.

Results

In buccolingual view of radiographs, the WVC and EM groups showed significantly lower percent-age of voids (P value<0.05) compared to that in the GF group. In mesiodistal view, the WVC and EM groups showed significantly lower percentage of voids (P value<0.05) compared to that in the GF and ES groups. In stereomicroscope evaluation, the WVC and EM groups showed significantly lower percentage of voids (P value<0.05) compared to that in the GF and ES groups. The differences observed between the WVC and EM groups (P value>0.05) or between the GF and ES groups (P value>0.05) were not significant.

Conclusion

WVC technique and single-cone technique with EM sealer are the optimum methods to fill ar-tificial resorption cavities.

The fate of root canals obturated with Thermafil: 10-year data for patients treated in a master's program

OBJECTIVES

Retrospective description of the 10-year success rate of endodontic treatments with Thermafil (TF).

MATERIALS AND METHODS

Patients treated by postgraduate students in an Endodontics Master's Program (2006-2008) were enrolled. All treated root canals were filled with TF and AH Plus. Teeth satisfying the inclusion criteria (206 teeth in 89 patients) were reexamined clinically and radiographically to estimate a 10-year survival and periapical health. Demographic and medical data were registered; collected information included pre-, intra-, and postoperative variables. Teeth were classified as "healthy" (PAI ≤ 2 in absence of signs/symptoms), "endodontically diseased" (presenting at least one of the following: PAI ≥ 3, signs/symptoms, retreated in the course of the follow-up, or extracted for endodontic reasons), or "non-endodontically diseased" (extracted for non-restorable fractures or periodontal disease). For teeth lost during the 10-year follow-up, details and reason of extraction were analyzed. Two PAI-calibrated examiners assessed outcomes blinded to preoperative status. Bivariate and multilevel analyses were performed (α level set at 0.05).

RESULTS

At 10 years, 179 (87%) teeth survived and 27 were extracted: 20 for non-endodontic reasons (excluded from success analysis) and 7 for endodontic reasons (considered "endodontically diseased"). Multilevel analysis revealed that the probability of extraction was increased by the presence of preoperative pain (odds ratio = 6.720; 95% confidence interval, 1.483-30.448) and by maxillary location (odds ratio = 2.950; 95% confidence interval, 1.043-8.347). Concerning periapical status, 159/186 teeth (85%) were assessed as "healthy." Multilevel analysis confirmed that maxillary location (odds ratio = 3.908; 95% confidence interval, 1.370-11.146), presence of flare up (odds ratio = 9.914; 95% confidence interval, 2.388-41.163), and fracture occurrence (odds ratio = 35.412; 95% confidence interval, 3.366-372.555) decreased the odds of healing, respectively.

CONCLUSIONS

After 10 years, teeth filled with Thermafil in a specialist master's program presented a survival and a periapical health comparable to cohorts where root canals were filled with other obturation techniques.

CLINICAL RELEVANCE

Carrier-based techniques provide time savings for clinicians while satisfying clinical quality criteria for the root filling and consequently the clinical outcome.

3D Micro-CT Analysis of Void and Gap Formation in Curved Root Canals

Objective:

This study used microcomputed tomography (micro-CT) to compare the volumes of voids and gaps in curved root canals instrumented and filled using various techniques.

Methods:

Twenty extracted mandibular first molars with two curved mesial root canals were used. Root canals were instrumented using a self-adjusting file (SAF) or Revo-S file system. For standardization, mesiobuccal canals were instrumented with SAF and mesiolingual canals were instrumented with Revo-S in each root. The canals were divided into four experimental groups (n=10 in each). The canals were then filled via cold lateral compaction (CLC) or a thermoplasticized injectable technique (TT) using gutta-percha and AH Plus root canal sealer. The roots were scanned with a micro-CT, and the volumes of the voids and gaps were calculated using three-dimensional (3D) micro-CT images. Data were analyzed using unpaired t- and Kruskal-Wallis tests. A value of P<0.05 was considered significant.

Results:

None of the tested techniques provided void- or gap-free fillings. Nevertheless, the SAF showed more gap formation than the Revo-S, and TT showed higher gap formation in all experimental groups. These differences, however, were not statistically significant (P>0.05).

Conclusion:

The SAF and Revo-S rotary file systems yielded comparable results. No statistically significant difference was found between the results of the various instrumentation and filling techniques.

Temperature Changes on External Root Surfaces with the Use of Several Thermoplastic Filling Techniques

INTRODUCTION

The purpose of this study was to measure the temperature rise on the external root surface of filled root canals using Touch'n Heat (Analytic Endodontics, Orange, CA), the TC System (TC; Tanaka de Castro & Minatel Ltda, Cascavel, PR, Brazil), and the Tagger technique.

METHODS

Forty-five single-canal mandibular premolar human teeth were used in the 3 experimental groups. The root canals were enlarged to accommodate up to an R40 Reciproc file (VDW, Munich, Germany). Next, the specimens were filled according to the technique evaluated. The measurement of the temperature was performed by K chromium-aluminum thermocouples attached to the coronal, middle, and apical root levels.

RESULTS

There was a significant difference among the 3 techniques (P < .001) in relation to the temperature variation between the highest temperature and the initial temperature. The highest temperature change was found with the Tagger technique at the middle third root level (11.8°C), and the lowest variation was in TC at the cervical third (2.05°C).

CONCLUSIONS

There was a rise of temperature on the external root surface for all of the techniques evaluated. TC showed the lowest temperature rise.

Evaluation of the Quality of Obturation with Obtura at Different Sizes of Apical Preparation Through Microleakage Testing

INTRODUCTION

Obturation of the root canal system is required to prevent recontamination of the root canal after cleaning and shaping procedures and to seal the root canal completely, both the apical and coronal avenues of potential leakage and to maintain the disinfected status.

AIM

The aim of this study was to determine the microleakage by dye leakage method at 1mm, 3mm and 5mm short of the apex with different sizes of apical preparation, obturated by Obtura.

MATERIALS AND METHODS

Sixty freshly extracted human single rooted teeth were randomly distributed into six equal groups. Group I (control group) was obturated by lateral compaction technique. Group II to VI were experimental groups (apical preparations done upto ISO sizes 20, 30, 40, 50 and 60 respectively), obturated by Obtura technique. After storing the samples at 100% humidity for seven days and one day in 2% methylene blue, the roots of the teeth were sectioned at 3mm short of the apex. They were observed under stereomicroscope at 20X magnification and the images were analysed for microleakage using the scoring criteria. The data obtained were analysed by One-way ANOVA followed by Tukey pair-wise multiple comparison test and p ≤ 0.05 was considered as the level of significance.

RESULTS

The lowest mean microleakage score was seen in Group VI (0) and the highest mean leakage score was seen in Group II (1.5). There was statistically significant difference between Group II and Group V (p = 0.044), Group II and Group VI (p = 0.013). There was no significant difference between all the other groups (p> 0.05).

CONCLUSION

Comparison of microleakage between different groups from ISO sizes 20-60 recommends a minimum apical preparation of ISO size 30.

Microscopic assessment of the sealing ability of three endodontic filling techniques

Background

Several techniques have been proposed for root canal filling. New rotary files, with non-standardized taper, are appearing, so, points adapted to the taper of the last instrument used to prepare the canal can help in the obturation process. The aim of this study is to assess the sealing ability of different root canal filling techniques.

Material and Methods

Root canals from 30 teeth were shaped with Mtwo and divided in three groups; A, standard lateral condensation with size 35 and 20 gutta-percha points; B, standard lateral condensation and injected gutta-percha; C, single gutta-percha point (standardized 35 Mtwo), continuous wave technique and injected gutta-percha. Root surfaces were covered with nail varnish, except for the apical 2 mm, and submerged in a NO3Ag2 solution; apical stain penetration was measured in mm. Data were compared using the Kruskal-Wallis test with a 90% confidence interval.

Results

A and B groups showed stain leakage in the 90% of the cases, whereas it was of 80% for group C. Stain leakage intervals were 1-5 mm for groups A and B and 1-3 mm for group C. There were no statistically significant differences between the three studied groups (p>.05).

Conclusions

All the analyzed root canal filling techniques showed some apical stain leakage, without significant differences among them.

Key words:Gutta-percha filling, microleakage, single cone, injected gutta-percha, warm gutta-percha.

Quality of root canal fillings using three gutta-percha obturation techniques

Objectives

The goal of this study was to compare the density of gutta-percha root fillings obturated with the following techniques: cold lateral (CL) compaction, ultrasonic lateral (UL) compaction, and warm vertical (WV) compaction.

Materials and Methods

Thirty-three extracted mandibular first molars, with two separate mesial canals in each, were selected. After instrumentation, the canals were stratified into three groups based on canal length and curvature, and underwent obturation with one of the techniques. No sealer was used in order to avoid masking any voids. The teeth were imaged pre- and post-obturation using micro-computed tomography. The reconstructed three-dimensional images were analyzed volumetrically to determine the amount of gutta-percha present in every 2 mm segment of the canal. P values < 0.05 were considered to indicate statistical significance.

Results

The overall mean volume fraction of gutta-percha was 68.51 ± 6.75% for CL, 86.56 ± 5.00% for UL, and 88.91 ± 5.16% for WV. Significant differences were found between CL and UL and between CL and WV (p < 0.05), but not between UL and WV (p = 0.526). The gutta-percha density of the roots treated with WV and UL increased towards the coronal aspect, but this trend was not noted in the CL group.

Conclusions

WV compaction and UL compaction produced a significantly denser gutta-percha root filling than CL compaction. The density of gutta-percha was observed to increase towards the coronal aspect when the former two techniques were used.

The effect of obturation technique on the push-out bond strength of calcium silicate sealers

INTRODUCTION

Calcium silicate-based sealers are known to have excellent sealing ability and bioactivities. They are typically recommended to be used in a single-cone (SC) technique. No studies have evaluated the effects of the thermoplastic obturation technique on the dentin interface of these sealers. The purpose of this study was to evaluate the push-out bond strengths of MTA Plus Sealer (Avalon Biomed Inc, Bradenton, FL) and EndoSequence BC Sealer (BC; Brasseler USA, Savannah, GA) when they were used in a thermoplastic technique.

METHODS

Fifty single-rooted human extracted teeth were randomly divided into 5 groups (n = 10), instrumented, and obturated with the SC technique or continuous wave (CW) technique: group 1, BC-SC; group 2, BC-CW; group 3, MTA Plus-SC; group 4, MTA Plus-CW; and group 5, AH Plus (Dentsply DeTrey, Konstanz, Germany)-CW. The roots were sectioned into 1.0-mm-thick slices, and bond strengths were measured using a standardized push-out test. The mode of failure was determined by visual inspection under magnification.

RESULTS

The MTA Plus-CW had statistically significant lower bond strengths than all other groups. The BC-SC group had statistically higher bond strengths than the MTA Plus-SC and AH Plus-CW groups. No significant differences were seen among the other groups. Modes of failure were predominately cohesive or mixed except for group 4 (ie, MTA Plus-CW) in which nearly half the specimens had no visible sealer.

CONCLUSIONS

BC and MTA Plus sealer showed favorable bond strengths when used in an SC technique. The CW obturation technique decreased the bond strengths of these sealers.

Sealer penetration into dentinal tubules in the presence or absence of smear layer: a confocal laser scanning microscopic study

INTRODUCTION

The aim of this study was to test the dentinal tubule penetration of AH26 (Dentsply DeTrey, Konstanz, Germany) and MTA Fillapex (Angelus, Londrina, PR, Brazil) in instrumented root canals obturated by using cold lateral compaction or warm vertical compaction techniques in either the presence or absence of the smear layer.

METHODS

Forty-five extracted single-rooted human mandibular premolar teeth were used. The crowns were removed, and the root canals were instrumented by using the Self-Adjusting File (ReDent-Nova, Ra'anana, Israel) with continuous sodium hypochlorite (2.6%) irrigation. Final irrigation was either with 5% EDTA or with sodium hypochlorite. The canals were dried and obturated by using rhodamine B-labeled AH26 or MTA Fillapex in combination with the cold lateral compaction or the warm vertical compaction technique. After setting, the roots were sectioned horizontally at 4-, 8-, and 12-mm distances from the apical tip. On each section, sealer penetration in the dentinal tubules was measured by using confocal laser scanning microscopy.

RESULTS

Regardless of the usage of EDTA, MTA Fillapex, compared with AH26, was associated with greater sealer penetration when used with the cold lateral compaction technique, and, conversely, AH26, compared with MTA Fillapex, was associated with greater sealer penetration when used with the warm vertical compaction technique (P < .05). Removal of the smear layer increased the penetration depth of MTA Fillapex used with the cold lateral compaction technique (P < .05); however, it had no significant effect on the penetration depth of AH26.

CONCLUSIONS

Greater sealer penetration could be achieved with either the MTA Fillapex-cold lateral compaction combination or with the AH26-warm vertical compaction combination. Smear layer removal was critical for the penetration of MTA Fillapex; however, the same did not hold for AH26.

Comparative analysis of three different filling techniques and the effects of experimental internal resorptive cavities on apical microleakage

Objectives:

The aim of this study was to evaluate the sealing abilities of three different gutta-percha techniques in experimentally defective roots (EDR) and non-defective roots (NR).

Materials and Methods:

Sixty canine teeth were divided into six groups of ten; Group 1, NR + cold lateral condensation (CLC); Group 2, EDR + LC; Group 3, NR + BeeFill; Group 4, EDR + BeeFill; Group 5, NR + Thermafil; and Group 6, EDR + Thermafil. Apical leakage was measured using a computerized fluid filtration meter with a laser system.

Results:

Statistical analysis revealed that the CLC demonstrated more microleakage in the EDR than in the NR (P < 0.01). Thermafil demonstrated more microleakage in the NR than in the EDR (P < 0.01). No statistically significant differences were found between the BeeFill groups (P > 0.05).

Conclusions:

The results of this study indicate that internal resorptive cavities can affect the apical sealing properties of different root canal filling techniques, with Thermafil ensuring the lowest apical microleakage.

Effect of several thermoplastic canal filling techniques on surface temperature rise on roots with simulated internal resorption cavities: an infrared thermographic analysis

AIM

To evaluate the surface temperature rise using an infrared thermal imaging camera on roots with and without simulated internal resorption cavities, during canal filling with injectable (Obtura II), carrier-based (Soft-Core) gutta-percha and continuous wave of condensation (System B) techniques.

METHODOLOGY

Root canals of 60 mandibular premolar teeth were instrumented to an apical size of 40. Circular artificial internal resorption cavities with a diameter of 2.40 mm were prepared on the root canal walls of 30 teeth. All teeth were divided into six groups of 10 specimen and root filled as follows: group 1 (teeth with internal resorption): thermoplasticized injectable gutta-percha (Obtura II), group 2 (teeth without internal resorption): thermoplasticized injectable gutta-percha (Obtura II), group 3 (teeth with internal resorption): carrier-based gutta-percha (Soft-Core), group 4 (teeth without internal resorption): carrier-based gutta-percha (Soft-Core), group 5 (teeth with internal resorption): continuous wave of condensation (System B) and group 6 (teeth without internal resorption): continuous wave of condensation (System B). The surface temperature changes during filling of canals were measured with an infrared thermal imaging camera. The thermograms were recorded at 2-s intervals over a period of 40 s to determine the maximum temperature rise at the apical, middle and cervical thirds of the root surface. The data were statistically analysed with one-way anova and Tukey HSD post hoc or Kruskal-Wallis and Bonferroni-adjusted Mann-Whitney U-tests if appropriate.

RESULTS

The temperature rise on the surface of roots with artificial resorptive defects was significantly higher compared with the ones without defects in the Obtura II and System B groups (P < 0.001). The System B group with internal resorption was associated with the maximum temperature rise in the apical (4.3 ± 2.1) and middle (19.5 ± 8.9) thirds amongst the groups (P < 0.001).

CONCLUSION

Use of System B and Obtura II for filling canals with internal resorptive cavities resulted in surface temperature rise over the critical threshold. However, Soft-Core root filling did not increase the temperature over 10 °C.

Fabrication and characterization of polymer composites for endodontic use

AIM

To develop a low-density polyethylene-hydroxyapatite (HA-PE) composite with properties tailored to function as a potential root canal filling material.

METHODOLOGY

Hydroxyapatite and polyethylene mixed with strontium oxide as a radiopacifier were extruded from a single screw extruder fitted with an appropriate die to form fibres. The composition of the composite was optimized with clinical handling and placement in the canal being the prime consideration. The fibres were characterized using infrared spectroscopy (FTIR), and their thermal properties determined using differential scanning calorimetry (DSC). The tensile strength and elastic modulus of the composite fibres and gutta-percha were compared, dry and after 1 month storage in simulated body fluid (SBF), using a universal testing machine. The radiopacity of the fibres was determined using digital radiography. The interaction of the composites with eugenol was evaluated and compared with gutta-percha. Data of the tensile test were submitted to two-way anova and Bonferroni tests (P < 0.05).

RESULTS

The endothermic peaks obtained from the DSC studies showed that the melting point of the HA/PE composites ranged between 110.5 and 111.2 °C, whereas gutta-percha exhibited a melting point at 52 °C. The tensile strength and elastic modulus of the silanated HA/PE composites were significantly higher than those of gutta-percha (P < 0.0001) under dry conditions and 1 month storage in SBF. The gutta-percha in eugenol showed a significant increase in the polymer molar mass, whereas the silanated HA/PE composites were unchanged. Radiological evaluations demonstrated that silanated HA/PE fibres were sufficiently radiopaque.

CONCLUSION

Promising materials for endodontic applications have been developed, offering relevant benefits over the traditional materials in terms of mechanical and chemical properties.

Quality of different gutta-percha techniques when filling experimental internal resorptive cavities: a micro-computed tomography study

The purpose of this ex vivo study was to determine the quality of root fillings in experimental internal resorptive cavities filled using cold lateral condensation (CLC), vertical condensation and Thermafil techniques. Forty-five extracted maxillary canine teeth were selected. After root canal instrumentation, the roots were sectioned horizontally and experimental internal resorption cavities were prepared. The root sections were re-approximated with a luting agent and randomly assigned to three groups (n = 15) to be filled using CLC, vertical condensation and Thermafil, respectively. Assessment of obturation quality in the internal resorptive cavity was performed using a desktop X-ray micro focus computed tomography scanner, and the percentage of gutta-percha (GP), sealer and voiding was calculated for each specimen. Data were statistically analysed using non-parametric tests, with P < 0.05 denoting a statistically significant difference. Vertical condensation filled 96.25 ± 8.31% of the total artificial cavity, and was superior to CLC (63.20 ± 16.87%) and Thermafil (59.26 ± 18.47%). The mean percentage of voids was 3.75 ± 8.31% in the vertical condensation group, 37.09 ± 17.13% in the CLC group and 41.06 ± 18.60% in the Thermafil group. We conclude that obturation of experimental resorption cavities is significantly better when using vertical condensation than when using other GP-based techniques.

Lack of correlation between obturation limits and apical leakage

The aim of this paper was to evaluate a possible correlation between obturation limits and leakage. Thirty-six extracted human mandibular incisors were used, characterized by straight and single canals, non-anatomical complexities, absence of previous endodontic treatment, complete root formation and patent foramen. For standardization of the specimens for the leakage analysis, foraminal instrumentation was performed up to a Flexofile #25 (Dentsply-Maillefer, Ballaigues, Switzerland). All specimens were instrumented and filled following the same protocol, and the obturation limits were measured using Axiovision 4.5 Software (Carl Zeiss Vision, Hallbergmoos, Germany). The specimens were then separated into three groups (n=12) according to the following variables: Group I--obturation limits ranging from 0 mm to 0.76 mm of the main apical foramen. Group II--obturation limits ranging from 0.77 mm to 0.98 mm of the main apical foramen. Group III--obturation limits ranging from 0.99 mm to 1.68 mm of the main apical foramen. Apical leakage was quantified by fluid filtration. The analyses were confronted using Pearson's test (p>0.05). Groups I, II and III showed Pearson correlation values (r2) of -0.152, -0.186 and 0.058, respectively. No correlation was found between the obturation limits and apical leakage.

Effect of various endodontic solutions on punch out strength of Resilon under cyclic loading

Background:

Before obturation, various endodontic solutions are used as a final rinse. These solutions might affect the bond strength of Resilon-Epiphany system. The aim of this study was to evaluate the effect of NaOCl (5.25%), chlorhexidine CHX (2%), EDTA solution (17%), and BioPure MTAD on push out bond strength of Resilon-Epiphany system.

Materials and Methods:

Seventy-five human premolar roots were prepared and divided on the basis of final endodontic solution rinse. The canals were obturated with Resilon-Epiphany system. All samples were restored using a fiber post system and indirect composite crown. The samples received 150 000 cycles of mechanical loading. Push out bond strength was performed in the apical third of root having Resilon obturation.

Results and Conclusions:

Different endodontic solutions tested, did not affected the push out bond strength of Resilon-Epiphany obturation system.

Comparative evaluation of sealing properties of different obturation systems placed over apically fractured rotary NiTi files

Aim:

To evaluate sealing properties of different obturation systems placed over apically fractured rotary NiTi files.

Materials and Methods:

Forty freshly extracted human mandibular premolars were prepared by using Protaper (Dentsply-Maillefer, Ballaigues, Switzerland) or the RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) systems (n=20 for each), after which half of the specimens were subjected to instrument separation at the apical level. Roots with and without apically separated instruments (n=5) were filled with the two obturation systems i.e. Thermafil and lateral compaction technique. The modified glucose penetration setup was used to assess the microleakage. The leakage data was statistically analyzed.

Results:

The amount of leakage was significantly lower in specimens containing fractured instruments, regardless of the obturation method used. Roots obturated with Thermafil displayed significantly less leakage than cold lateral compaction technique, both, in the presence and absence of separated instruments. There was no significant difference among specimens prepared with ProTaper and RaCe when Thermafil obturation was done. But with cold lateral compaction technique, RaCe system showed less leakage as compared to ProTaper system.

Conclusion:

The type of obturation may play more important role than the type of instrument or retained/non-retained instrument factor.

Comparative analysis of carrier-based obturation and lateral compaction: a retrospective clinical outcomes study

The purpose of this retrospective study was to compare the outcome of primary endodontic treatment using a standardized cleaning and shaping technique and obturation with either lateral compaction or carrier-based obturation. Patients received primary endodontic treatment in the predoctoral dental clinic using a standardized cleaning and shaping protocol. All root canals were obturated using AH Plus^TM sealer with lateral compaction of gutta-percha (LC) or carrier-based obturation (CBO). A total of 205 cases met the inclusion criteria. 71 teeth in 60 patients were recalled after 2 years and evaluated both clinically and radiographically by two independent examiners. Success was defined as a lack of clinical symptoms and a normal periodontal ligament space or reduction in size of a previously existing periapical radiolucency. Chi-square and logistic regression were used for statistical analysis with a significance level of P < 0.05. There was no difference in success rates between cases obturated with LC or CBO (P = 0.802); overall success rate was 83%. Molars had a significantly lower success rate (53%) than premolar and anterior teeth (89%) (P = 0.005), irrespective of the obturation technique used. When a standardized cleaning and shaping protocol was used by predoctoral dental students in a controlled university setting, there was no difference in success rates between cases obturated with LC or CBO.

Comparison of laterally condensed, vertically compacted thermoplasticized, cold free-flow GP obturations - A volumetric analysis using spiral CT

AIM/OBJECTIVE

To compare the laterally condensed gutta-percha, vertically compacted thermoplastized gutta-percha (E and Q Plus system) and cold free-flow gutta-percha (GuttaFlow). This is a volumetric analysis using spiral CT, an in vitro study.

MATERIALS AND METHODS

Access cavities were prepared in 60 single rooted anterior teeth; cleaning and shaping was done and obturated with three of the different techniques: group A: cold lateral; group B: vertically compacted thermoplasticized and group C: cold free-flow obturation techniques. Volume analysis was done using spiral computed tomography (CT). The percentage difference was calculated and statistically analyzed using one-way ANOVA and post hoc multiple comparison Tukey HSD tests.

RESULTS

There were statistical significant differences between group A (0.183cm(3)) and group B (0.136cm(3)); group A (0.183cm(3)) and group C (0.128cm(3)). But there was no statistical significance between group B (0.136cm(3)) and group C (0.128cm(3)).

CONCLUSION

Within the limitations of this in vitro study it can be concluded that cold free-flow obturation technique showed the highest volume of obturation, followed by the vertically condensed thermoplasticized technique. The least volume of obturation was observed in cold lateral condensation technique.

Limited ability of three commonly used thermoplasticized gutta-percha techniques in filling oval-shaped canals

The present study was designed to compare the percentage of gutta-percha-filled area (PGFA) achieved in oval-shaped canals after filling by 3 thermoplasticized techniques. Eighty-seven oval-shaped root canals were prepared and root-filled as follows: lateral condensation (n = 20), thermomechanical compaction (n = 20), wave of condensation (n = 20), and Thermafil system (n = 20). A cross section of each tooth was made 5 mm from the apex, and the samples were prepared for microscopic analysis. Digital image measurements of the cross-sectioned area of the canal and the gutta-percha were performed, and the PGFA was calculated. Nonparametric statistical analysis was performed with the Kruskal-Wallis H test and post hoc Dunn test. Overall, PGFAs were variable among the experimental groups, ranging from 37.1%-98.5%, and the pooled data from all techniques had a general mean of 69.6% +/- 18%. Thermafil system, wave of condensation, and thermomechanical compaction produced significantly higher PGFAs than lateral condensation (P < .05); however, no significant differences among these techniques were detected (P > .05). Therefore, a limited ability to fill oval-shaped canals was achieved in the 3 thermoplasticized techniques tested.

A comparison of 5 gutta-percha obturation techniques to replicate canal defects

OBJECTIVE

The purpose of this study was to compare the ability of five different methods of compaction of thermoplasticized GP to replicate four artificially-created defects in the canal walls of an extracted tooth. One of the instruments tested was the EndoTwinn which was recently introduced to the U.S. market and can be used in both the warm lateral (WLC) and warm vertical compaction (WVC) techniques.

STUDY DESIGN

Four artificially-created defects were created in the dentinal walls of a split-tooth model which could be separated after each obturation and the obturation mass removed for visual evaluation. Twenty obturations were evaluated for each of the following techniques: Group 1, WLC without vibration using the EndoTwinn; Group 2, WLC with heat and vibration using the EndoTwinn; Group 3, WVC using the Elements Obturation System (EOS); Group 4, Injectable GP using the EOS; and Group 5, WVC using the EndoTwinn. Kruskal-Wallis statistic was used to determine statistically significant differences, pairwise comparisons were analyzed with the Mann Whitney statistic and a Bonferonni adjustment was made, where indicated.

RESULTS

Nonparametric analyses with appropriate Bonferroni adjustments indicated statistically significant results favoring Groups 2 and 4.

CONCLUSIONS

The EndoTwinn, in heat and vibration mode, and the EOS resulted in better replication of the defects than the other techniques.