Comparison of two vertical condensation obturation techniques: Touch 'n Heat modified and System B

A Literature Review of the Effect of Heat on the Physical-Chemical Properties of Calcium Silicate-Based Sealers

INTRODUCTION

Recently, calcium silicate-based sealers (CSSs) have gained popularity in endodontic practice due to their biocompatibility and antimicrobial properties. They are considered viable alternatives to epoxy resin-based sealers. With the increased use of CSSs and warm vertical compaction techniques in root canal treatment, evaluating the impact of heat on CSSs properties is essential, therefore this review aimed to present a qualitative synthesis of available in vitro studies assessing the impact of heat on the physical-chemical properties of CSSs.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guidelines, a systematic advanced electronic search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases in November 2023 and updated in April 2024. In vitro studies that evaluated the physical-chemical properties of CSSs were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias-included studies.

RESULTS

The search identified a total of 6421 preliminary results and 10 studies were included for qualitative assessment. Eleven different physiochemical properties were assessed by the included studies. Setting time and flow were the most evaluated property among the studies. A qualitative synthesis of the evidence on each property is presented.

CONCLUSIONS

Based on the in vitro studies assessed in the present systematic review, results reveal that exposing CSSs to heat can accelerate their setting time, reduce their flow, and increase their film thickness. Concerns persist regarding solubility, viscosity, radiopacity, dimensional change, microhardness, porosity, and compressive strength, requiring further research. Certain CSSs, such as MTA Fillapex and Endosequence BC sealer HiFlow, show minimal changes under heat, making them potential candidates for warm filling techniques.

Postoperative pain after root canal filling with bioceramic sealers: a systematic review and meta-analysis of randomized clinical trials

The aim of this systematic review and meta-analysis (SRM) was to assess postoperative pain (PP) after endodontic treatment with bioceramic root canal sealer compared to AH Plus® sealer. This SRM was carried out in accordance with the items on the PRISMA 2020 checklist and Cochrane guidelines and registered in PROSPERO (CRD42021259283). Only randomized clinical trials (RCTs) were included. Meta-analysis was conducted using R software, the standardized means difference (SMD) measure of effect was calculated for quantitative variables, and the odds ratio (OR) for binary variables. The Cochrane tool (RoB 2.0) was used to assess the risk of bias, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess the quality of evidence. Qualitative and quantitative analysis included 18 and 17 studies, respectively. For quantitative variables, the bioceramic root canal sealer presented less occurrence of postoperative pain than the AH Plus® sealer in 24 h (SMD - 0.17 [- 0.34; - 0.01], p = 0.0340). For binary variables, there was no difference observed between the sealers evaluated, except for sealer extrusion where the bioceramic group had lower post-filling material extrusion (OR 0.52 [0.32; 0.84], p = 0.007). Regarding the risk of bias analysis, low risk was observed for most domains, except allocation that was considered unclear, while the certainty of evidence ranged from moderate to low. The results showed that bioceramics sealers reduced postoperative endodontic pain only after 24 h and showed less sealer extrusion compared to the AH Plus® sealer. However, more robust and standardized clinical trials are needed to confirm the results with less heterogeneity and higher quality of evidence.

Thermal, chemical and physical analysis of VDW.1Seal, Fill Root ST, and ADseal root canal sealers

This study aimed to evaluate the thermal, chemical, and physical properties of VDW.1Seal, Fill Root ST, and ADseal sealers. Thermal properties were analyzed using Thermogravimetric analysis (TGA) and Differential thermal analysis (DTA). Attenuated total reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) analysis was performed as a complementary test to confirm TGA/DTA analysis. The chemical composition of the set sealer material was identified using an X-ray powder diffraction (XRD) system. Other physical properties of each sealer were investigated; ten specimens were used to measure the solubility (at 24 h and 28 days), and another ten specimens were used to assess pH changes and calcium ion release (after 7 and 14 days). Film thickness was done according to ISO 6876 specs. The data were analyzed using the two-way ANOVA test. Results showed that for all sealers, TGA analysis revealed a direct relationship between sealer mass loss and temperature rise. In addition, the decomposition of the tested sealers started at 145 °C, 135 °C and 91 °C for VDW.1Seal, ADseal sealer, and Fill Root ST, respectively. XRD analysis revealed a higher degree of crystallinity for VDW.1Seal and ADseal. ADseal showed the least solubility; VDW.1Seal exhibited the highest alkalinity, calcium ion release, and the lowest film thickness.

External Root Surface Temperature Control with 1,1,1,2-Tetrafluoroethane Intracanal Cryotherapy during Thermoplastic Obturation: An In Vitro Study

AIM

The aim of this in vitro study was to determine the effectiveness of 1,1,1,2-tetrafluoroethane (TFE) intracanal cryotherapy for external root surface temperature control during thermoplastic obturation.

MATERIALS AND METHODS

Thirty extracted adult single-rooted mandibular incisors were selected for this study. Endodontic shaping was performed until size X3 Protaper Next Rotary endodontic file. The teeth were divided into three groups: Group I-Control group wherein conventional irrigation was done using physiologic saline stored at room temperature, Group II-Irrigational Cryotherapy group using physiologic saline at 2.5°C, and Group III-Intracanal TFE cryotherapy group with intracanal refrigerant TFE application. Temperatures were recorded in the apical 3 mm before and after completion of each intervention and post thermoplastic obturation using a noncontact digital laser infrared thermometer.

RESULTS

Intracanal cryotherapy with TFE resulted in a mean decrease of 9.27°C compared with conventional irrigation that exhibited in a mean decrease of 2.13°C. Also, in intracanal cryotherapy group with TFE application, compared with the baseline (24.50°C), no significant differences were observed post obturation (24.61°C) with high-temperature-injectable gutta percha technique indicating good control of temperature rise on the external root surface.

CONCLUSION

Intracanal cryotherapy with refrigerant TFE was highly effective in controlling temperature rise on the external root surface during injectable thermoplastic obturation technique.

CLINICAL SIGNIFICANCE

Minimizing deleterious effects due to high temperatures generated during the thermoplastic obturation is critical. Clinically feasible measures to reduce the transmission of heat generated during thermoplastic obturation have been searched since long. In this regard, intracanal cryotherapy with TFE can be effectively used to control the rise of temperature on the external root surface when employing thermoplastic obturation technique.

Evaluation of the Physicochemical and Biological Properties of EndoSequence BC Sealer HiFlow

INTRODUCTION

Understanding the physicochemical and biological properties of endodontic sealers is important for endodontic treatment planning. This study evaluated the properties of EndoSequence BC Sealer HiFlow (BCH; Brasseler USA, Savannah, GA), EndoSequence BC Sealer (BC, Brasseler USA), and AH Plus (AHP; Dentsply DeTrey, Konstanz, Germany). The effect of temperature on the setting time and flow of these sealers was also evaluated.

METHODS

The setting time, flow, radiopacity, pH, solubility, and calcium release were investigated following ISO guidelines. The morphology and chemical composition of the sealers were evaluated by scanning electron microscopy and energy-dispersive spectroscopy. The antibacterial activity of sealers was tested against 2 strains of Enterococcus faecalis. Sealer cytotoxicity and the effects on messenger RNA expression of proinflammatory and mineralization genes were also investigated. Data analysis was performed using analysis of variance, Tukey, Kruskal-Wallis, and Dunn multiple comparison tests. P ≤ .05 was considered statistically significant.

RESULTS

The setting time and flow rate of all sealers were affected by heat (P ≤ .05). The setting times and solubility of BCH and BC were significantly higher than AHP (P ≤ .0001). The radiopacity of AHP was higher than BCH and BC (P ≤ .0001). All sealers were alkaline and had antibacterial effects. Cell viability was higher for BCH and BC than AHP (P ≤ .0001). No significant differences in messenger RNA expression of proinflammatory and mineralization genes were observed.

CONCLUSIONS

Overall, BCH and BC had similar physicochemical and biological properties. The observed high solubility of BCH and BC as well as the high cytotoxicity of AHP might negatively impact the clinical performance of these materials. The application of heat affected the setting time and flow of all sealers.

Evaluation of the sealer/gutta-percha ratio on sets of root section surfaces of some extracted teeth sealed using the cold lateral condensation technique

Canal filling must be well adapted to the walls of the root canal to prevent bacterial infiltration. Endodontic seals play an essential role in ensuring tightness, without which the canal filling would suffer infiltrations. This study aimed to evaluate the areas occupied by the two components of the canal filling, as well as the sealer/gutta-percha ratio in the root canals of the maxillary central incisors after their filling using the cold lateral condensation technique with gutta-percha. Thirty extracted upper central incisors were rotatably prepared with ProTaper Universal up to F3 and sealed using the cold lateral condensation technique with gutta-percha. After setting the sealer, the roots of the teeth were sectioned perpendicularly to 1 (L1), 3 (L3), 6 (L6), and 8 (L8) mm from the apex. The surface of the sections was analyzed with a Leica EZ4D stereomicroscope and photographed at two magnification orders: 10x and 25x. The areas corresponding to the gutta-percha, sealer, gaps, and root canal were expressed in pixels using the ImageJ software, version 1.50i. The difference in the representation of sealer areas, gutta-percha and voids was statistically significantly different for all four sections analyzed. The best adaptation of the canal obturation was observed in L1 and L3. The gutta-percha area was statistically significantly higher than that of the sealer for the L1, L3, and L6 levels, while the sealer/gutta-percha ratio recorded the lowest value at the L3 level (0, 30) and the highest at its L8 (0.70) level, without registering statistically significant differences regarding the area at the four analyzed levels. The voids were mostly absent or recorded a minimal percentage area (<1%). Cold lateral condensation of gutta-percha has led to a good adaptation of gutta-percha to the root canal wall, with a small amount of sealer, especially to the sections made at 3 mm from the apex. Given the limitations of this study, we noted that the voids were few – observed in the 6 and 8 mm sections – and were negligible in many cases.

Heat Generation Changes with Electrically Heated Pluggers after Multiple Autoclave Cycles at Different Operating Temperatures

INTRODUCTION

Electrically heated pluggers are the most commonly used instruments during warm obturation techniques. This study aimed to evaluate the effect of sterilization and operating temperature settings on the heat generation of pluggers of various taper sizes.

METHODS

Fifty pluggers were sterilized at 132°C for 25 minutes for a total of 150 cycles. One group (Autoclave200) consisted of 25 pluggers tested at an operating temperature setting of 200°C, whereas another group (Autoclave400) consisted of 25 pluggers tested at 400°C. The heat generation at their tip surface was measured with T-type thermocouples at 0, 50, 100, and 150 autoclave cycles. An unpaired t test was used to compare the time it took the pluggers to reach 60°C and the mean maximum temperature change.

RESULTS

After 50 autoclave cycles, all of the 0.04 taper pluggers in Autoclave200 failed to reach 60°C. After 100 autoclave cycles, one of the 0.10 taper pluggers in Autoclave200 did not reach 60°C, and after 150 autoclave cycles, one of the 0.04 taper pluggers failed to generate any heat. The mean increase in the time to reach 60°C ranged from 1071-4004 milliseconds and 510-2074 milliseconds for Autoclave200 and Autoclave400, respectively. The mean maximum temperature change decreased by 13-29°C and 24-116°C for Autoclave200 and Autoclave400, respectively.

CONCLUSIONS

After multiple autoclave cycles and higher operating temperature use, the electrically heated pluggers transferred less heat to the tip surface, potentially making them less effective.

The single cone obturation technique with a modified warm filler

OBJECTIVES

The aim of this study was to develop a new method of obturation by warm sealer in conjunction to single cone gutta-percha and evaluate the suitability of this technique to obturate complex root canal systems.

METHODOLOGY

Three root canal sealers namely, AH Plus, BioRoot RCS, GuttaFlow and a prototype sealer composed of tricalcium silicate and 30% zirconium oxide mixed with water and water-soluble polymer were investigated. The sealers were tested for flow, film thickness, setting time and radiopacity following ISO 6876 (2012) recommendations at room temperature and following heat application at 100°C to change the sealer properties. All the test sealers were characterized by scanning electron microscopy and energy dispersive spectroscopy. The volume of voids when used with a single cone obturation technique both unmodified and modified by heat was evaluated using microcomputed tomography.

RESULTS

Although the prototype sealer was designed to be similar to the BioRoot, its physical properties were found to be different. All sealers tested were affected by the heat and exhibited a change in the physical properties mainly the setting time, flow, film thickness and void volume.

CONCLUSIONS

The application of heat affected the sealer properties and void volume. The single cone obturation technique may not be suitable for complex canal anatomy and furthermore, AH Plus should not be subjected to high temperatures as its properties deteriorate and void volume increases.

Plugger temperature of cordless heat carriers according to the time elapsed

Objective

The purpose of this study was to measure the temperature of the plugger tip of 3 cordless heat carriers set at 200°C.

Materials and Methods

Pluggers of the same taper (0.06, 0.08, 0.10) and similar tip sizes (sizes of 50 and 55) from 3 cordless heat carriers, namely SuperEndo-α² (B & L Biotech), Friendo (DXM), and Dia-Pen (Diadent), were used and an electric heat carrier, System B (SybronEndo), was used as the control. The plugger tips were covered with customized copper sleeves, heated for 10 seconds, and the temperature was recorded with a computerized measurement system attached to a K-type thermometer at room temperature (n = 10). The data were analyzed with 2-way analysis of variance at a 5% level of significance.

Results

The peak temperature of the plugger tips was significantly affected by the plugger taper and by the heat carrier brand (p < 0.05). The peak temperature of the plugger tips was between 177°C and 325°C. The temperature peaked at 207°C-231°C for the 0.06 taper pluggers, 195°C-313°C for the 0.08 taper pluggers, and 177°C-325°C for the 0.10 taper pluggers. Only 5 of the 12 plugger tips showed a temperature of 200°C ± 10°C. The time required to reach the highest temperature or 200°C ± 10°C was at least 4 seconds.

Conclusion

When using cordless heat carriers, clinicians should pay attention to the temperature setting and to the activation time needed to reach the intended temperature of the pluggers.

Efficacy of a new Activation Device in Irrigant Penetration Into Simulated Lateral Canals

Objective:

The aim of the present study was to compare the effects of EasyClean (EC) on irrigant delivery into simulated lateral canals using an artificial closed canal system. Passive ultrasonic irrigation (PUI) was used as a reference technique for comparison.

Methods:

Forty simulated curved root canals manufactured in transparent resin and with simulated lateral canals were instrumented with Reciproc R40 files and randomly assigned to four groups (n=10) according to the irrigant activation technique: PUI group, ECrec group (EC used in reciprocating motion), ECrot group (EC used in rotary motion), and control group (no activation performed). After activation, stereomicroscope images from each block were taken, and irrigant penetration into lateral canals was measured using Adobe Photoshop software. Data were analysed using ANOVA and Tukey’s post hoc test (α=0.05).

Results:

No penetration was observed in the control group. The ECrec group showed lower penetration than the other group (P<0.05). No differences were observed between the ECrot group and the PUI group (P>0.05).

Conclusion:

EC used in rotary motion was effective in increasing the penetration of the irrigating solution into simulated lateral canals.

Comparison of bacterial leakage resistance of various root canal filling materials and methods: Confocal laser-scanning microscope study

This study evaluated the bacterial leakage resistance and root canal lining efficacy of various root canal filling materials and methods by using confocal laser-scanning microscope (CLSM). Sixty extracted human premolars with mature apex and single root canal were randomly divided into 2 control groups and 4 experimental groups. Group CW was filled with continuous wave technique using gutta-percha and AH Plus sealer. Group GC was coated with AH-Plus sealer and then obturated with soften GuttaCore. Group GF was obturated using GuttaFlow and gutta-percha. Group EM was filled with EndoSeal MTA and gutta-percha using ultrasonic vibration. The AH-Plus, GuttaFlow, and EndoSeal were labeled with Hoechst 33342 to facilitate fluorescence. The obturated root tip was incubated with Carboxyfluorescein diacetate succinimidyl ester (CFSE)-stained E. faecalis for 14 days. CLSM was performed to evaluate the sealer distribution and bacterial leakage for the apical 1-, 2-, 3-mm specimens. Statistically significant differences were determined by 1-way ANOVA with Tukey's post-hoc test and Pearson's correlation analysis. Group EM showed the better sealer distribution score than the other groups (p < 0.05). Group CW and group GC exhibited the less bacterial leakage than the group GF, while group EM showed the similar bacterial leakage score with the groups CW and GC. There was no significant correlation between the sealer distribution and bacterial leakage (p > 0.05). Under the conditions of this study, different root canal filling materials and methods showed different efficacy for canal distribution and bacterial leakage resistance.

Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction

The aim of this study was to evaluate the ability of gutta-percha and a thermoplastic synthetic polymer (Resilon) to fill simulated lateral canals, using warm vertical compaction. Forty-five single-rooted human teeth were prepared using the rotary crown-down technique. Artificial lateral canals were made at 2, 5, and 8 mm from the working length (WL) in each root. The specimens were divided into three groups (n = 15), according to the filling material: Dentsply gutta-percha (GD), Odous gutta-percha (GO), and Resilon cones (RE). The root canals were obturated using warm vertical compaction, without endodontic sealer. The specimens were subjected to a tooth decalcification and clearing procedure. Filling of the lateral canals was analyzed by digital radiography and digital photographs, using the Image Tool software. The data were subjected to the Kruskal-Wallis and Dunn tests at 5% significance. RE had the best filling ability in all root thirds (p < 0.05), with similar results for GO in the coronal third. In the middle and apical thirds, GD and GO had similar results (p > 0.05). Resilon may be used as an alternative to gutta-percha as a solid core filling material for use with the warm vertical compaction technique. The study findings point to the potential benefit of the warm vertical compaction technique for filling lateral canals, and the study provides further information about using Resilon and gutta-percha as materials for the warm vertical compaction technique.

Radiographic evaluation of root canal cleaning, main and laterals, using different methods of final irrigation

OBJECTIVE: To evaluate the efficacy of passive ultrasonic irrigation (PUI) using intermittent or continuous flushing and conventional manual irrigation (CMI) on the cleaning of main and simulated lateral root canals.MATERIAL AND METHOD: The root canals of 24 artificial teeth were prepared and simulated lateral canals were made in the medium and apical thirds of the root. The specimens were divided into three groups: G1- CMI, G2- PUI 1 (intermittent flushing) and G3- PUI 2 (continuous flushing). Root canals were filled with contrast solution and the roots were radiographed pre- and post-irrigation. The digital images were transferred to Image Tool 3.0 software and the areas of root canal completely filled with contrast, and after irrigation with contrast remnant, were measured to obtain percentage data. Statistical analysis between groups was performed by ANOVA and Tukey tests.RESULT: In the apical third, G2 and G3 (PUI) groups showed higher percentage of cleaning than G1 (CMI) (p<0.05).CONCLUSION: Passive ultrasonic irrigation using intermittent flushing promoted a higher cleaning of simulated lateral canals than conventional manual irrigation in the apical third. There were no differences between groups in the main root canal and the middle third.

Heat conductive properties of set root canal sealers

OBJECTIVE

The aim of this study was to examine the thermal conductivity of five different root canal sealers in vitro.

MATERIALS AND METHODS

Sealapex, AH Plus, AH 26, Endomethasone and RoekoSeal root canal sealers were examined. These materials were prepared in accordance with the manufacturer's instructions and applied to standard molds. Three samples of each material were prepared. The samples were kept for 5 days under 37°C conditions. Measurements were taken using a heat conduction unit (P.A. Hilton Ltd. Stockbridge, Hants, UK). The thermal conductivity coefficient was calculated for each sample using the Fourier equation. Coefficients were analyzed statistically by the Kruskal-Wallis test.

RESULTS

Significant differences were found for thermal conductivity between some materials (p < 0.05). The conductivity coefficient of AH Plus was found to be higher than those of the other materials (p < 0.05). No statistically significant differences were found between AH 26 and RoekoSeal (p > 0.05) and the conductivity coefficients of these sealers were found to be lower than those of the other materials (p < 0.05). No statistically significant differences were found between Sealapex and Endomethasone (p > 0.05) and the conductivity coefficients of these sealers were found to be lower than that of AH Plus but higher than those of RoekoSeal and AH26 (p < 0.05).

CONCLUSIONS

The results showed that root canal sealers functioned as thermal insulators and had different heat-conductive properties that depended on their composition.

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique

OBJECTIVES

The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1.

MATERIALS AND METHODS

Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth.

RESULTS

Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region.

CONCLUSIONS

These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system.

CLINICAL RELEVANCE

These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.

Evaluation of epoxy resin sealer after three root canal filling techniques by confocal laser scanning microscopy

The aim of this study was to evaluate the penetration of endodontic sealer into the dentin tubules, the integrity of the sealer layer perimeter, and the sealer area at the apical third after different filling techniques by confocal laser scanning microscopy (CLSM). Forty-five mandibular premolars were mechanically prepared with ProTaper files, until F5 file. Thereafter, they were filled with an epoxy-resin sealer (AH Plus) mixed with Rhodamine B dye (0.1% proportion) and allocated in three groups: Group 1, single master cone; Group 2, cold lateral compaction; and Group 3, Thermafil. For confocal laser scanning microscopy analysis, the specimens were transversely sectioned at 4 mm from the apex. The images at ×10 and ×40 were analyzed by Imagetool 3.0 software. Significant differences were not found among the three experimental groups according the dentin-impregnate area by the sealer (P = 0.68) and between the sealer and root canal perimeter (P = 0.18). However, root canal filling techniques were significantly different when apical sealer areas were compared (P = 0.001). Thermafil group showed smaller sealer areas (8.09%) while cold lateral compaction and gutta-percha master cone showed similar areas (17.37 and 21.18%, respectively). The dentin-impregnated area was not dependent on the root canal filling technique. Single master cone, cold lateral condensation and Thermafil techniques presented integrity of the sealer perimeter close to 100% and Thermafil resulted in a significantly thinner sealer layer.

Percentage of gutta-percha in mesial canals of mandibular molars obturated by lateral compaction or single cone techniques

The aim of this study was to compare the percentage of gutta-percha (PGP) in mesial root canals of mandibular molars obturated with LC (Lateral Compaction) or SC (Single Cone) ProTaper Universal System techniques at different levels of the root. Mesial root canals of 20 human permanent molars with similar anatomical characteristics were instrumented using the ProTaper Universal rotary system technique until the F2 instrument, with 20 canals filled by SC ProTaper Universal technique and 20 canals by the LC technique. The mesial roots were sectioned transversely to 3, 5, and 7 mm from the root apex. Digital images of specimens were obtained at MIC-D digital microscope in increases of 30 to 35X. The gutta-percha area was measured using ImageTool software. Data were analyzed using two-way ANOVA and Bonferroni test (α = 0.05). The SC technique provided greater PGP than the LC technique in the apical third (3 mm) (P < 0.001). In the other thirds (5 and 7 mm) there was no statistical difference between the two techniques regarding the PGP (P > 0.05). There was no statistically significant difference between thirds of the root canal for both techniques (P > 0.05). It was concluded that SC technique provided greater PGP than the LC technique in the apical third of mesial root canals of mandibular molars. There was no difference between the two techniques regarding the PGP in the cervical and middle thirds.

Effect of canal taper and plugger size on warm gutta-percha obturation of lateral depressions

This study used transparent epoxy-resin root canal models to evaluate different main root canal tapers and various methods of vertical compaction for warm gutta-percha obturation of lateral depressions. The root canal models had straight main root canals with three tapers and four lateral depressions at right angles to the main root canal, 1.0 mm and 3.0 mm from the apex. Three types of experimental stainless steel pluggers with different flat-tip diameters and tapers were used to compact the warm gutta-percha. The Obtura II was used for obturation. After obturation, the depth of penetration into lateral depressions was measured under a stereoscopic microscope, and the effects of root canal taper and plugger size were analyzed by using two-way analysis of variance. The penetration of warm gutta-percha into lateral depressions using the smallest-diameter plugger decreased with increasing main root canal taper. Penetration into lateral depressions increased with the use of pluggers of the correct size. There was a close relationship between plugger size and canal taper. The results suggest that main root canal taper and plugger size should be closely matched so as to promote gutta-percha obturation of lateral depressions.

Technique acquisition in the use of two thermoplasticized root filling methods by inexperienced dental students: a microcomputed tomography analysis

INTRODUCTION

Limited endodontic experiences in dental schools suggest the need for easy-to-learn techniques. Therefore, two simplified root filling methods were assessed for adequacy and expediency when performed by inexperienced students.

METHODS

Eight students were trained (45-minute lecture and 90-minute practice) in use of ProTaper Obturators (PTO) and System-B/Calamus (SBC). They subsequently filled the root canals in two extracted, single-rooted teeth per method (n = 32). Canals were preshaped and prefitted with obturators and master cones. The volume of root-filling voids determined by microcomputed tomography imaging in 1-mm increments, time to complete fillings, and students' responses in questionnaires were analyzed (independent-sample t test and Mann-Whitney U test).

RESULTS

PTO had a significantly smaller void volume in the apical 6 mm of canals (P < 0.001), required significantly shorter time (P < 0.001), and was perceived as easier to learn and use but less likely to be favored after graduation than SBC.

CONCLUSION

These results suggested that the PTO root filling method was particularly suitable for teaching when endodontic experiences available for students are limited.

Filling of artificial lateral canals and microleakage and flow of five endodontic sealers

AIM

To evaluate the flow characteristics of AH Plus, Epiphany Root Canal Sealant, Endométhasone, Pulp Canal Sealer (EWT) and Sealapex and their ability to fill artificial lateral canals and prevent microleakage.

METHODOLOGY

Flow of the sealers was analysed using the American Dental Association (ADA) 57 and the International Standards Organization (ISO) 6,876 specifications. Two lateral canals were produced in the middle and apical third of 64 roots using 0.1 mm cylindrical drills. Lateral condensation of gutta-percha or Resilon and one or other of the sealers were used to fill the root canals. Buccal-lingual digital radiographs were exposed. After the sealer had set, the roots were immersed in Indian ink and cleared in methyl salicylate. The extent of filling and dye penetration were measured on the buccal and lingual root surfaces under 30 x magnification with a stereoscope.

RESULTS

AH Plus, Epiphany and Pulp Canal Sealer (EWT) complied with ADA 57 and ISO 6,876 specifications. Sealapex complied with the ADA 57 specification but not with ISO 6,876. Endométhasone did not comply with either specification. Filling of lateral canals was similar for the five sealers tested. Dye leakage demonstrated that AH Plus, Epiphany and Sealapex permitted less leakage than Pulp Canal Sealer (EWT) (P < 0.05).

CONCLUSIONS

All the sealers flowed into the 0.1 mm artificial lateral canals. AH Plus, Epiphany and Sealapex allowed less linear leakage than Pulp Canal Sealer (EWT). The flow of Endométhasone did not comply with either ADA 57 or ISO 6,876 specifications and Sealapex did not comply with ISO 6,876.

Comparison of the percentage of gutta-percha-filled area obtained by Thermafil and System B

The aim of this study was to determine the percentage of gutta-percha-filled area (GPFA) obtained by Thermafil and System B techniques using light microscopy and digital image processing. Forty-five human mandibular first molars were prepared and obturated as follows: Group 1: lateral condensation (n = 15); Group 2: System B (n = 15); and Group 3: Thermafil system (n = 15). Horizontal sections were cut 4 and 6 mm from the apical foramen of each tooth. The samples were metallographically prepared and taken through photomicrographs. Using digital analysis, the cross-sectional area of the canal and the gutta-percha areas were measured. The GPFA data obtained for the three groups were analysed using the non-parametric Friedman and Wilcoxon Signed-Ranks tests. Significant differences were found between Group 3 and Group 2-Group 1. No significant difference was found between Group 2 and Group 1. The Thermafil system produced significantly higher GPFAs than lateral condensation and System B techniques (P < 0.01). This result suggests that the Thermafil system can reduce sealer and voids.

Sealer area associated with cold lateral condensation of gutta-percha and warm coated carrier filling systems in canals prepared with various rotary NiTi systems

AIM

To compare the area of sealer surrounding root fillings completed by two coated carrier systems (Thermafil Obturator and System GT Obturator) and the cold lateral compaction technique, following root canal preparation with two different NiTi rotary systems (Profile ISO and System GT).

METHODOLOGY

Sixty extracted human mandibular premolars were instrumented with ProFile ISO 0.06 taper and System GT instruments (n = 30 each). The teeth were divided into four subgroups (n = 15) for filling as following: group 1: ProFile + Thermafil Obturator, group 2: ProFile + Cold Lateral Compaction, group 3: System GT + GT Obturator, and group 4: System GT + Cold Lateral Compaction. In all groups the canals were prepared to a final size of 40, 0.06 taper in accordance with the manufacturer's instructions and Topseal was used as a sealer. Horizontal sections were obtained every 1 mm up to 12 mm from the apical foramen. Sections were digitally photographed under a stereomicroscope and the images were transferred to an IBM-compatible PC for image analysis. The cross-sectional area of the root canal and the area filled by sealer were calculated for each section and compared statistically both at all levels and by grouping the data as apical, middle and coronal segments; using the Kruskal-Wallis test with Bonferroni correction and chi-square tests (P = 0.05).

RESULTS

In the apical third (1-4 mm), the GT Obturator (group 3) had significantly less area of sealer (P < 0.05), while the difference between groups 1 and 2 was not significant (P > 0.05). For the middle and coronal thirds, both coated-carrier systems had significantly less area of sealer compared with their laterally compacted counterparts (P < 0.05).

CONCLUSIONS

With the combined use of ProFile + Thermafil Obturator and System GT + GT Obturator, significantly less area of sealer occurred than that achieved with both NiTi preparation systems followed by cold lateral compaction.

An ex vivo comparison of three different gutta-percha cones when compacted at different temperatures: rheological considerations in relation to the filling of lateral canals

AIM

To compare ex vivo the penetration of three brands of gutta-percha cones, compacted under a constant force and heated to different temperatures, into artificial lateral canals.

METHODOLOGY

Resin blocks with simulated main canals, each having two lateral canals (C at 6.5 and A at 13 mm from the surface of the resin block), were selected. A gutta-percha cone, either Mynol MF, Hygenic MF or GT Tulsa 0.04 was compacted into each main canal for 5 s using a wire rod with a diameter of 0.7 mm soldered to the bottom of a metal cylinder, with a force of 2.7 kg at controlled temperatures of 37, 42, 47, 52, 60 degrees C. The penetration of each brand of gutta-percha into 60 lateral canals (10 at each temperature) was measured using a stereomicroscope. Statistical analysis was performed using the ANOVA, the Scheffè test and the t-test.

RESULTS

None of the three brands of cones entered up to 0.1 mm within either lateral canal until a temperature of 47 degrees C was reached; at that temperature only Mynol cones (P < or = 0.05) penetrated in four of 10 A-level canals (mean 0.13 +/- 0.19 mm) and in all 10 C-level canals (mean 0.43 +/- 0.12 mm). The A-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.76 +/- 0.34 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.31 +/- 0.12 mm) and Hygenic cones (mean 0.11 +/- 0.08 mm). At 60 degrees C the Mynol cones (mean 1.93 +/- 0.34 mm) penetrated significantly more (P < or = 0.05) than the Tulsa cones (mean 0.86 +/- 0.22 mm) and Hygenic cones (mean 0.67 +/- 0.19 mm). The C-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.91 +/- 0.29 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.47 +/- 0.16 mm) and Hygenic cones (mean 0.46 +/- 0.15 mm), whilst no significant difference was found at 60 degrees C.

CONCLUSIONS

When heated and compacted, the three gutta-percha cones penetrated the lateral canals to different degrees. They penetrated more than 0.43 mm into the lateral canals only at temperatures higher than 47 degrees C.

The percentage of gutta-percha-filled area in simulated curved canals when filled using Endo Twinn, a new heat device source

AIM

To compare the percentage of gutta-percha-filled area (PGP) in simulated root canals when varying the penetration depth and function of the pluggers (heat versus heat plus vibration) using Endo Twinn.

METHODOLOGY

Sixty-four resin blocks with simulated 34-35 degrees curved canals were randomly divided into two groups in order to obtain two canal shapes: group A with 0.8 taper and group B with 0.4 taper. The apical portion of each canal was prepared to a size 20 K-file. The canals were filled with gutta-percha in combination with a root canal sealer. In each group 16 canals were filled using the Endo Twinn heat function and 16 canals by means of both the heat and the vibration function. All samples were sectioned horizontally at three levels (1.25, 2.5 and 4.0 mm from the working length) and the PGP was measured. Data were analysed using ANOVA test.

RESULTS

At the 1.25 mm level PGP was significantly greater using the vibration function (P = 0.0329) and in 0.8 taper canals (P < 0.0001). At the 2.5 mm level the PGP was greater in the canals with 0.8 taper compared with a 0.4 taper with or without vibration (vibration, P = 0.0056; interaction taper-vibration, P = 0.0020). In 0.4 taper canals the PGP was greater when the vibration function was activated. At the 4 mm level in 0.8 taper canals there was no significant difference in PGP with or without the vibration (P = 0.6742).

CONCLUSIONS

0.8 taper canals had significantly greater PGP than 0.4 taper canals. At the 1.25 mm level there was significantly greater PGP when the vibration function was activated.

A laboratory analysis of gutta-percha-filled area obtained using Thermafil, System B and lateral condensation

AIM

To determine the percentage of gutta-percha-filled area (PGFA) in the apical third of root canals when filled with either Thermafil, System B or lateral condensation.

METHODOLOGY

Sixty extracted human maxillary central incisor teeth were root filled as following: G1: lateral condensation (n = 20), G2: System B (n = 20) and G3: Thermafil system (n = 20). A horizontal section was cut 2 and 4 mm from the apical foramen of each tooth. The samples were prepared for microscopic analysis and photomicrographs of each apical surface were taken at a magnification of 50x. Through digital image analysis, the cross-sectional area of the canal and the gutta-percha was measured. The PGFA was calculated. The PGFA data obtained in the three groups were analysed using a nonparametric Friedman and Wilcoxon signed-rank tests.

RESULTS

Significant differences in PGFA were found between the Thermafil System (G3) and both System B (G2) and lateral condensation (G1) (P < 0.01). The greatest PGFA occurred in the Thermafil group. No significant statistical difference was found between System B and lateral condensation (P > 0.05).

CONCLUSIONS

The coated carrier gutta-percha system Thermafil produced significantly higher PGFAs than lateral condensation and System B techniques.

A comparison of thermal properties between gutta-percha and a synthetic polymer based root canal filling material (Resilon)

A new polymer-based obturating material, Resilon, has been developed but there have been no studies identifying its thermal properties. The purpose of this study was to compare the melting point, specific heat, enthalpy change with melting and heat transfer between gutta-percha (GP) and Resilon (R). The first three tests were determined using a differential scanning calorimeter and the heat transfer test was determined using a split-tooth model. Results show no significant difference (t test, p > 0.05) between gutta-percha and Resilon for the melting point temperature (GP: 60.01 degrees C; R: 60.57 degrees C). There was a significant difference (t test, p < 0.05) in specific heat capacity (GP: 0.94 J/g degrees C, R: 1.15 J/g degrees C) and endothermic enthalpy change (GP: 10.88 J/g, R: 25.20 J/g) between the two materials. The heat transfer test showed a significant difference (Mann-Whitney, p < 0.05) in temperature increase between gutta-percha and Resilon within 3 mm of the heat source.

A 1-year follow-up study on leakage of single-cone fillings with RoekoRSA sealer

OBJECTIVE

The aim of this study was to measure long-term leakage along single cone (SC) fillings.

STUDY DESIGN

Two groups of canines (n = 30) were prepared and a size 55 file was the apical master file. Step-back was performed using files of sizes 60, 70, and 80. The canals were filled by the single cone technique using RoekoRSA as sealer. To place sealer into each canal, a bidirectional spiral was used in 1 group, whereas a gutta-percha cone was used in the other group. Immediately after root filling, the coronal portion of root filling was removed by postspace preparation. Leakage along the 4 mm remaining apical root filling was measured after 1 week and again after 1 year using a fluid transport model. Ten additional canine roots were prepared and filled with gutta-percha cones without sealer, serving as positive controls. Occurrence of apical extrusion of materials was recorded.

RESULTS

The apical root filling in all 60 canine roots did not show leakage either at 1 week or at 1 year. All 10 positive controls showed gross leakage (>20 muL/h). In no case gutta-percha extruded through the apical foramen. Sealer extruded apically in 88% of the roots where a gutta-percha cone was used to introduce sealer, whereas in 28% of the roots where a bidirectional spiral was used to introduce sealer (by chi-square test, P < .05).

CONCLUSION

In wide and straight canals, SC fillings with RoekoRSA sealer prevented fluid transport for 1 year. Using bidirectional spiral to place sealer reduced sealer extrusion under the conditions of this experiment.

An In Vitro Model to Investigate Filling of Lateral Canals

Aims of this work were to examine lateral canals in extracted teeth, to propose a new technique to produce artificial lateral canals, and to compare two obturation techniques. Cleared roots were examined to record measure and shape of lateral canals. Artificial lateral canals were prepared on human demineralized teeth before final clearing. Specimens were divided in two groups: canals of group 1 were filled with Schilder's technique, canals of group 2 were filled with vertical compaction with apical backfilling. Stereomicroscopic analysis of lateral canal filling revealed lower filling rates in apical canals compared to coronal ones and higher filling rates with "vertical compaction with apical backfilling" compared to Schilder's group. The tested procedure appears to be a reliable technique to obtain standardized lateral canals and to compare filling procedures.

An evaluation of the quality of root fillings in mandibular incisors and maxillary and mandibular canines using different methodologies

OBJECTIVES

To evaluate the quality of root fillings in mandibular incisors and maxillary and mandibular canines using different methodologies of evaluation, namely radiographs, the fluid transport test and the percentage of gutta-percha (PGP), and to determine if a correlation occurs between the results of the different methodologies used.

METHODS

One group of mandibular incisors with oval canals (n=20) and one group of maxillary and mandibular canines (n=20) were instrumented and obturated by cold lateral compaction using AH 26 as the sealer. The filled roots were bucco-lingually and mesio-distally radiographed. Using a scoring system, the quality of each root filling was radiographically evaluated, the higher the score the poorer the quality. Fluid transport along the root filling was then measured using a fluid transportation device. Each root was horizontally sectioned 4 and 6mm from the apex. Images of the cross-sections were taken, using a microscope and a digital camera. Images were scanned into a PC as TIFF images. Using a KS 100 Imaging system the canal area and the gutta-percha filled areas were measured. The percentage of gutta-percha filled areas was calculated.

RESULTS

Considering the radiographic scores of the two different projections together the score was significantly higher for the mandibular incisors than for the canines (P=0.039). The radiographic score was significantly higher for the mesio-distal radiograph in comparison with the bucco-lingual radiograph (P=0.0001), for the canines as well as the incisors. Using only the bucco-lingual radiograph there was no significant difference between the mandibular incisors and the canines (P=0.992). The mandibular incisors displayed significantly more fluid transport than the canines (P=0.049). A significantly greater percentage of gutta-percha filled areas was found in the cross-sections of canines as compared to the cross-sections of mandibular incisors (P=0.000001). The correlation between the radiographic score of the mesio-distal radiograph and the PGP 4 and 6mm was significant (P=0.013). There was no significant correlation between the FT and the radiograph or the FT and the PGP.

CONCLUSIONS

The quality of the root fillings in oval canal-mandibular incisors may be compromised.

Comparison of cold lateral compaction and continuous wave of obturation techniques following manual or rotary instrumentation

AIM

To compare different combinations of root canal preparation and obturation technique.

METHODOLOGY

A total of 48 freshly extracted human maxillary central incisors were divided into two identical groups on the basis of root canal length and apical diameter. The root canals were prepared by manual crown-down pressureless technique or with a rotary system (ProFile; Dentsply Maillefer, Ballaigues, Switzerland) in a crown-down technique. The coronal diameter and apical size of the root canals were standardized in both preparation techniques. Each main group was then divided into two subgroups and obturated with either cold lateral compaction or continuous wave of obturation with System B (EIE-Analytic Technology, Orange, CA, USA). The distribution of filling material in each canal was assessed by stereomicroscopic examination of eight cross-sections on each tooth. Areas of sealer, gutta-percha and voids were measured on the digital images of a total of 384 samples. Manipulation time and apical extrusion for each group was also determined. Data were statistically analysed using Kruskal-Wallis, anova (Bonferroni/Dunn) or Student's t-test.

RESULTS

The percentage of sealer, gutta-percha and voids area between the obturation techniques was not significantly different (P > 0.05). Continuous wave groups had significantly more apical extrusion of sealer (P < 0.05), while none of the obturation techniques had gutta-percha extrusion. Rotary instrumentation was significantly faster than the manual technique (P < 0.05); continuous wave obturation was significantly faster than lateral compaction (P < 0.05). Total manipulation time in the rotary/continuous wave group was significantly shorter than the other groups (P < 0.0001).

CONCLUSION

The distribution of filling materials was similar in all combinations of instrumentation and obturation techniques. The continuous wave technique was faster than lateral compaction and it extruded more sealer.

Root surface temperature rises during root canal obturation, in vitro, by the continuous wave of condensation technique using System B HeatSource

OBJECTIVES

This in vitro study evaluated increases in root surface temperature during the continuous wave of condensation technique using a System B HeatSource.

STUDY DESIGN

Forty-five extracted human teeth (15 maxillary central incisors, 15 mandibular central incisors, and 15 maxillary canines) were used. After root canal cleaning and shaping, the teeth were filled with the continuous wave of condensation technique using a System B HeatSource. Temperature changes on the whole mesial and vestibular outer surfaces of the roots were measured using an infrared thermal imaging camera.

RESULTS

The results of this in vitro study showed that the use of the continuous wave of condensation technique to fill the maxillary central incisors and maxillary canines produced temperature rises below the critical level. In the mandibular central incisors the use of a System B HeatSource resulted in elevation of the root surface temperature by more than 10 degrees C.

CONCLUSION

The continuous wave of condensation technique using the System B HeatSource produces temperature changes on the outer root surfaces, which, in the case of teeth with relatively thin dentinal walls, can reach relatively high values.

An evaluation of .06 tapered gutta-percha cones for filling of .06 taper prepared curved root canals

AIM

To compare the area occupied by gutta-percha, sealer, or void in standardized .06 tapered prepared simulated curved canals and in mesio-buccal canals of extracted maxillary first molars filled with a single .06 gutta-percha point and sealer or lateral condensation of multiple .02 gutta-percha points and sealer.

METHODOLOGY

Simulated canals in resin blocks with either a 30 degrees curve and radius of 10.5 mm (n = 20) or a 58 degrees curve and 4.7 mm radius (n = 20) and curved mesio-buccal canals of extracted maxillary first molars (n = 20) were prepared using .06 ProFiles in a variable tip crown-down sequence to an apical size 35 at 0.5 mm from the canal terminus or apical foramen. Ten 30 degrees and 58 degrees curved resin canals and 10 canals in the extracted teeth group were obturated with .02 taper gutta-percha cones and AH 26 sealer using lateral condensation. The time required to obturate was recorded. The remaining canals were obturated with a single .06 taper gutta-percha cone and AH 26 sealer. Excess gutta-percha was removed from the specimens using heat and the warm mass vertically condensed. Horizontal sections were cut at 0.5, 1.5, 2.5, 4.5, 7.5 and 11.5 mm from the canal terminus or apical foramen. Colour photographs were taken using an Olympus 35 mm camera attached to a stereomicroscope set at x40 magnification, and then digitized using a flatbed scanner. The cross-sectional area of the canal contents was analysed using Adobe PhotoShop. The percentage of gutta-percha, sealer or voids to the total root canal area were derived and data analysed using unpaired Student's t-test and the Mann-Whitney U-test.

RESULTS

In the 30 degrees curved canals the levels had between 94 and 100% of the area filled with gutta-percha with no significant difference (P > 0.05) between the lateral condensation and single cone techniques. In the 58 degrees curved canals the levels had 92-99% of the area filled with gutta-percha, with the single cone technique having significantly (P < 0.05) more gutta-percha fill at the 2.5 mm level only. In the mesio-buccal canals of the teeth the levels had between 72 and 96% of the area filled with gutta-percha with no significant difference (P > 0.05) between the lateral condensation and single cone technique. The time for obturation was significantly (P < 0.05) greater for lateral condensation compared with the single cone technique in all groups.

CONCLUSIONS

The .06 taper single cone technique was comparable with lateral condensation in the amount of gutta-percha occupying a prepared .06 tapered canal. The .06 single cone technique was faster than lateral condensation.