Evaluation of Apical Filling After Warm Vertical Gutta-Percha Compaction Using Different Procedures

The investigation of composition and thermal behavior of two types of backfilling gutta-percha

Background/purpose

In the warm gutta-percha technique, soft-type and regular-type gutta-percha are using for backfilling thermoplasticized injection system. However, there are limited reports about the properties of these backfilling gutta-percha. This study aimed to analyze and compare the composition, thermal behavior and compact force of two types of backfilling gutta-percha.

Materials and methods

Soft-type and regular-type backfilling gutta-percha (B&L BioTech, Fairfax, VA, USA) were investigated. The inorganic and organic fractions of these gutta-perchas were separated by quantitative chemical analysis (n = 6). Their composition was analyzed using energy dispersive spectroscopy. Thermal behavior in response to temperature variations was analyzed using differential scanning calorimetry. Additionally, a compaction model was used to investigate the relation between compaction force and temperature (n = 10).

Results

The soft-type contained more gutta-percha (3.69-5.85%), carbon ratio (38.96-48.52%) and less inorganic substance (86.51-90.45%), zinc ratio (29.36-35.67%). The composition ratio of two types gutta-percha were statistically significant different (P < 0.05). There were three phase transitions of the soft-type gutta-percha which started at 39.84 °C, 49.32 °C and 54.15 °C while the two phase transitions of the regular-type gutta-percha started at 40.48 °C and 53.45 °C. The glass transition temperature of the regular-type gutta-percha (44.24 °C) was higher than that of the soft-type gutta-percha (40.66 °C). Under various setting temperature, the higher compaction force in the regular-type gutta-percha was required (P < 0.05).

Conclusion

The different components in gutta-percha contribute to its differences in thermal behavior. The soft-type had a higher proportion of gutta-percha and lower ZnO which makes the fluidity better than the regular-type.

Assessment of the Dentinal Surface Adaptation Efficacy of Different Obturation Systems with Bioceramic Sealer: A Scanning Electron Microscope Study

AIM

Aim of this study was to evaluate the dentinal surface adaptation effectiveness of different obturation methods with bioceramic sealer.

MATERIALS AND METHODS

Sixty recently removed human permanent premolars of the mandible having a solitary, straight as well as completely produced root were chosen on the basis of clinical/radiographic evaluation. The coronal parts of the premolars were subjected to sectioning at the cementoenamel junction (CEJ) with the aid of a water-cooled diamond disk. The regular access opening was done, following which the working length was visually estimated by deducting 1 mm from the length of a 10 size K-file (Dentsply, OK, USA) at the apex. Subsequent to preparing the radicular canal, the premolar specimens were randomly allocated to one of the following three groups. Group I: Lateral compaction (LC) technique; group II: Warm vertical compaction (WVC) technique; and group III: Thermafil obturation technique. Following obturation, the samples were subjected to sectioning in the horizontal direction at three dissimilar points as follows: First at the cervical third, then at the middle, and at the apical third employing a minitom under water irrigation to put off overheating. Internal spaces amid the radicular dentin as well as the obturating agents were appraised with the use of a scanning electron microscope (SEM).

RESULTS

Intragroup analysis showed that higher gaps were noted at the coronal level (2.30 ± 0.04), in pursuit by middle part (1.12 ± 0.02) and apical third (0.70 ± 0.02) for the LC method. With the WVC procedure, higher gaps were situated in the coronal level (1.96 ± 0.07), again in pursuit by middle part (1.02 ± 0.02) and apical third (0.86 ± 0.04). Even with the Thermafil obturation method, higher gaps were noted at the coronal level (0.92 ± 0.10), in pursuit by middle part (0.67 ± 0.05) and apical third (0.57 ± 0.01). No statistically significant difference was noted within the group. Upon intergroup comparative assessment of dentinal surface adaptation with dissimilar obturation systems at coronal, middle and apical thirds, there was a statistically noteworthy disparity amid the groups (p <0.001).

CONCLUSION

This research arrived at a conclusion that the most superior dentinal adaptation of bioceramic sealer was procured when the Thermafil obturation method was employed for obturating the root canals compared to the WVC technique as well as the LC technique.

CLINICAL SIGNIFICANCE

Numerous endodontic substances have been promoted for obturating the root canal areas. Majority of the methods use a core substance, in addition to a sealer. Despite the type of core agent, a sealer indispensable to each technique offers a fluid-tight sealing. The oral physicians' comprehension of the characteristics of the endodontic sealer plus method used, enhances the therapeutic effect.

An In Vitro Comparative Evaluation of Apical Leakage Using Different Root Canal Sealers

Background

Successful endodontic therapy requires a fluid-tight apical seal. The aim of this in vitro study was to evaluate and compare the apical sealing ability of 3 root canal sealers: Apexit Plus, AH Plus, and Resilon/Epiphany sealers.

Material/Methods

Samples of 152 single-rooted teeth were divided into 2 test groups, and each group was divided into 3 subgroups based on the preparation and obturation technique. After preparation with the step-back technique, the first group of root canals were obturated with lateral gutta-percha compaction in combination with AH Plus sealer or Apexit Plus or with the Resilon/Epiphany system alone. In the second group, preparation was done with the crown-down technique and root canals were then obturated with Thermafil obturator in combination with AH Plus or Apexit Plus or with Resilon/Epiphany sealer alone. Apical leakage was determined using a dye leakage test observed with a stereomicroscope. The degree of dye leakage was assessed using the t test to comparing the arithmetic averages of the groups.

Results

In the groups prepared with the step-back technique, the average dye leakage was lower in samples obturated with Resilon/Epiphany, than in those filled with AH Plus/lateral gutta-percha compaction or Apexit Plus/lateral gutta-percha compaction. In groups prepared with the crown-down technique and obturated with the Resilon/Epiphany system, the average dye leakage was lower than in those filled with AH Plus/Thermafil obturation and those filled with Apexit Plus/Thermafil obturation.

Conclusions

Although all preparation and obturation techniques showed dye penetration, the crown-down technique paired with the Resilon/Epiphany system showed the least leakage.

An In vitro Comparison and Evaluation of Sealing Ability of Newly Introduced C-point System, Cold Lateral Condensation, and Thermoplasticized Gutta-Percha Obturating Technique: A Dye Extraction Study

Aim

The aim of this study is to compare and to evaluate sealing ability of newly introduced C-point system, cold lateral condensation, and thermoplasticized gutta-percha obturating technique using a dye extraction method.

Materials and Methodology

Sixty extracted maxillary central incisors were decoronated below the cementoenamel junction. Working length was established, and biomechanical preparation was done using K3 rotary files with standard irrigation protocol. Teeth were divided into three groups according to the obturation protocol; Group I-Cold lateral condensation, Group II-Thermoplasticized gutta-percha, and Group III-C-Point obturating system. After obturation all samples were subjected to microleakage assessment using dye extraction method. Obtained scores will be statistical analyzed using ANOVA test and post hoc Tukey's test.

Results

One-way analysis of variance revealed that there is significant difference among the three groups with P value (0.000 < 0.05). Tukey's HSD post hoc tests for multiple comparisons test shows that the Group II and III perform significantly better than Group I. Group III performs better than Group II with no significant difference.

Conclusion

All the obturating technique showed some degree of microleakage. Root canals filled with C-point system showed least microleakage followed by thermoplasticized obturating technique with no significant difference among them. C-point obturation system could be an alternative to the cold lateral condensation technique.

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.

Ability of Three Endodontic Sealers to Fill the Root Canal System in Association with Gutta-Percha

Introduction:

The present study compared the ability of the endodontic sealers AH Plus, Pulp Canal Sealer and EndoREZ to fill the root canal system in association with gutta-percha.

Methods:

Ninety mandibular premolars were accessed, prepared and divided into three groups of 30 teeth each, according to the sealer used to fill the canals: AH Plus, Pulp Canal Sealer and EndoREZ. All the teeth were filled using the continuous wave of condensation technique. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators with 8x magnification. Chi-squared test (χ², p < 0.05) was used to compare the groups in relation to the totally filled, the partially filled and the non filled ramifications. The same test was used to compare the directions of filled ramifications and the number of ramifications among the three thirds of the roots.

Results:

EndoREZ filled a significantly higher number of ramifications than AH Plus and Pulp Canal Sealer (χ², p < 0.05). All the groups showed higher number of totally filled ramifications than partially filled and unfilled ramifications. The ramifications were more frequently detected in the apical third, followed by medium and coronal thirds, respectively (χ², p < 0.05). The ramifications were more frequently detected towards lingual direction (χ², p < 0.05).

Conclusion:

EndoREZ presented higher ability to fill the root canal system in association with gutta-percha when compared to AH Plus and Pulp Canal Sealer. The ramifications were more frequently detected in the apical third, running in a lingual direction.

Obturation Techniques Allow Microbial Leakage Unless Protected

PURPOSE

To evaluate the quality of the apical 5-mm seal produced by different filling techniques using a bacterial leakage model.

MATERIALS AND METHODS

Sixty-five extracted single-rooted human teeth were decoronated, prepared, and instrumented. Roots were randomly divided into three experimental groups (15 roots each) and control groups (10 roots each). The apical 5 mm was filled with cold lateral condensation (CLC) technique, continuous wave of condensation (CWC), or injectable thermoplasticized gutta-percha (Obtura II) using AH26 Plus as a sealer. Positive controls were filled with gutta-percha without sealer, whereas negative controls were filled with a CLC technique and covered completely with two layers of nail varnish, including the orifice. A dual-chamber leakage model using Enterococcus faecalis as a microbial marker was used for leakage evaluation. Bacterial penetration was monitored over a 60-day period, and leakage was recorded when turbidity was observed in the lower chamber.

RESULTS

All positive controls exhibited turbidity in the lower chamber within 24 hours. All negative controls demonstrated no bacterial leakage for the entire 60-day observation period. The estimated mean day for leakage was 32 for CLC, 35 for CWC, and 30 days for Obtura II. Wilcoxon test showed no statistically significant difference (p = 0.98) in the survival time between the experimental groups.

CONCLUSION

The three filling techniques produced similar resistance to bacterial leakage when used to fill the apical 5-mm segment of the canal while leaving the rest of the canal unfilled.

Comparative evaluation of fracture resistance of root obturated with resilon and gutta-percha using two different techniques: an in vitro study

INTRODUCTION

Present study evaluated the fracture resistance of endodontically treated teeth filled with Gutta percha and a new resin based obturating material (Resilon).

MATERIALS AND METHODS

A total of 150 freshly extracted Mandibular premolar with fully formed apices were selected and decoronated at cemento-enamel junction (CEJ). Teeth were divided into Group A and Group B of 75 teeth each. In Group A canals were prepared up to # no 40 K file and Group B up to #no 80 K file. Both the groups were sub divided into five group of 15 teeth each as control group (unfilled canals), lateral condensation with Gutta-percha using AH 26 sealer, vertical condensation with Gutta-percha using AH 26 sealer, lateral condensation with Resilon using resilon sealer, vertical condensation with Resilon using resilon sealer. Each specimen was subjected to compressive load using Universal testing machine. The force required to fracture was recorded and data were analysed by ANOVA, Duncan's test and student T test.

RESULT

The result showed that there is statistically significant difference among experimental groups (p < 0.05). The groups with the Resilon material displayed higher mean fracture loads than the Gutta percha groups. No statistically significant differences were observed between different preparation techniques.

CONCLUSION

Obturating the canals with the new resin-based obturation material increases the in vitro fracture resistance of endodontically treated teeth when compared with standard Gutta percha techniques.

A Comparative Evaluation of Efficacy of Different Obturation Techniques used in Root Canal Treatment of Anterior Teeth: An in vitro Study

Aim: This study was undertaken to evaluate the percentage of gutta-percha-filled area (PGFA) using microscopic analysis of the cross-sections in the apical third of root canals when filled either with Thermafil technique, Warm Vertical Condensation technique and Cold Lateral Condensation technique without using sealers.

Materials and methods: Sixty single rooted extracted per-manent teeth were collected. After crown amputation, the teeth were randomly divided into three experimental groups of 20 specimens each. Group I–Thermafil obturation technique, group II–warm vertical condensation obturation technique and group III–cold lateral condensation obturation technique. Obturation was performed by specific techniques without using sealers. After obturation, the teeth were cross-sectioned horizontally at 2 to 3 mm from apex with the help of double sided diamond disk. Sections were digitally photographed and measured under Stereomicroscope at magnification of 50×.

Using a KS 100 imaging system the area of canals and the gutta-percha was recorded, also the percentage of gutta-percha filled area (PGFA) was calculated. The observations thus ob-tained were subjected to statistical analysis using ANOVA and student ‘t’ test.

Results: Maximum group difference was observed between groups I and III (3.558 ± 0.138) while minimum difference was observed between groups I and II (1.223 ± 0.137). Thus, all the between group differences were statistically significant.

Conclusion: This study supports the belief that the Thermafil Obturation technique produces significantly higher percentage of gutta-percha filled area (PGFA) than the warm vertical condensation technique or cold lateral condensation technique.

How to cite this article: Samadi F, Jaiswal JN, Saha S, Garg N, Chowdhary S, Samadi F, Tripathi VP. A Comparative Evaluation of Efficacy of Different Obturation Techniques used in Root Canal Treatment of Anterior Teeth: An in vitro Study. Int J Clin Pediatr Dent 2014;7(1):1-5.

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.

An in vitro comparison of bond strengths of Gutta-percha/AH Plus, Resilon/Epiphany self-etch and EndoREZ obturation system to intraradicular dentin using a push-out test design

Aim:

To evaluate and compare the push-out bond strengths of three obturation materials; Gutta-percha/AH Plus, Resilon/Epiphany self-etch (SE) and EndoREZ obturation system to intraradicular dentin.

Materials and Methods:

Sixty single-canal anterior teeth were prepared and assigned to experimental groups (n = 20), designated as Group I: Gutta-percha/AH Plus, Group II: Resilon/Epiphany SE and Group III: EndoREZ sealer/EndoREZ points. After obturation, each tooth was prepared for push-out assessment with root slices of 2 mm thickness using universal testing machine.

Statistical Analysis:

Two way analysis of variance and Scheffe's test.

Results:

Gutta-percha/AH Plus root fillings showed significantly highest bond strength. Also, root segment location did not have a significant influence on bond strength.

Conclusion:

The adhesiveness quality to root dentin promoted by newer methacrylate resin-based obturation systems like Resilon/Epihany SE and EndoREZ is compromised even when teeth with simple anatomic features were obturated under well-monitored laboratory conditions.

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.

Evaluation of apical microleakage of teeth sealed with four different root canal sealers

Objectives:

to compare the apical sealing ability of four root canal sealers. Materials and methods: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with guttapercha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal.

Results:

AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01).

Conclusions:

the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.

A comparative study on the frequency, location, and direction of accessory canals filled with the hydraulic vertical condensation and continuous wave of condensation techniques

The present study compared the frequency, location, and direction of accessory canals filled with two different filling techniques. Sixty-four mandibular first molars were accessed, prepared, and divided into two groups of 32 teeth each. The teeth from group A and group B were filled using the hydraulic vertical condensation technique and the continuous wave of condensation technique, respectively. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators. There was no significant difference (t test, p < 0.05) between the two groups in relation to the total number of filled ramifications. Moreover, there was no significant difference among the three thirds of the roots in relation to the number of filled ramifications (analysis of variance, p < 0.05). The filled ramifications were more frequently detected toward lingual, buccal, distal-lingual, and distal-buccal directions. It was concluded that the two filling techniques are not different in relation to the frequency, location, and direction of the ramifications filled.

Sealing properties of two contemporary single-cone obturation systems

AIM

To compare the sealing of root canals filled with two single-cone obturation systems and a warm vertical compaction technique.

METHODOLOGY

Forty-two single-rooted teeth were decoronated to obtain 17-mm-long root segments. The root canals were cleaned and shaped to size 40, 0.06 taper and filled with: (i) warm vertical compaction with AH Plus (control); (ii) ActiV GP and (iii) GuttaFlow with single master cones. Leakage was evaluated by fluid filtration at 10 psi before root resection, and after 3, 6, 9 and 12 mm apical resections. Repeated measures anovas on ranks and Dunn's multiple comparison tests were performed to examine differences in fluid flow rates amongst different resection lengths for each filling technique. The surface and interior aspects of glass-ionomer filler-coated ActiV GP gutta-percha cones was evaluated with SEM.

RESULTS

No statistical difference amongst the filling techniques was seen at 0 and 3 mm root resections. ActiV GP and GuttaFlow exhibited more leakage than AH Plus at 6, 9 and 12 mm resections. AH Plus recorded the best overall results. A nonhomogeneous coating of glass-ionomer fillers on the surface of ActiV GP cones was detected.

CONCLUSIONS

The two single-cone techniques examined are as effective in sealing the apex as AH Plus when the latter was used with warm vertical compaction. It is further hypothesized that the inferior coronal seal of these single-cone techniques may be improved with the placement of accessory cones to reduce sealer thickness or an immediate coronal adhesive restoration.

Negative influence of continuous wave technique on apical sealing of the root canal system with Resilon

The aim of this study was to investigate apical microleakage after use of the Resilon system in comparison with gutta-percha. The materials used were 54 mesial roots of mandibular molars with an apical curvature of 20-40 degrees . The root canals were instrumented with the Prosystem GT(R) and obturated with: Group I: Gutta-percha + Sealer by lateral condensation (n = 25); Group II: Gutta-percha + Sealer, complemented by System B and Obtura II (n = 25); Group III: Resilon + System B and Obtura II (n = 25); Group IV: Resilon by lateral condensation (n = 25). After immersion in India ink, the specimens were demineralized and rendered transparent. Apical dye leakage was analyzed with a stereomicroscope and a digital camera connected to a computerized system. All groups showed different degrees of apical dye microleakage. The Kruskal-Wallis test revealed that the largest leakage occurred in Group I (P < 0.05), whereas the other groups presented a similar pattern of microleakage (P > 0.05). Thermoplastification negatively influenced the apical sealing ability of Resilon. Gutta-percha points and conventional sealer yielded the highest values of apical leakage, especially when the lateral condensation technique was used. Regardless of the obturation technique employed, the Resilon system provided the lowest mean values of apical leakage, but did not provide hermetic sealing of the root canal system.

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.

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

A split-tooth model with artificially created intracanal wall defects was used to compare three gutta-percha (GP) obturation techniques, cold lateral, warm lateral, and warm vertical. The techniques were evaluated and compared based on defect replication quality as a function of defect location and size. The obturations were evaluated on an ordinal scale, 0 to 4, based on how much each defect was replicated. There was a statistically significantly better result with both warm techniques compared to cold lateral obturation, while there was no significant difference between the warm obturation techniques.

Evaluation of canal filling after using two warm vertical gutta-percha compaction techniques in vivo: a preliminary study

AIM

To evaluate the quality of root canal filling when comparing two warm gutta-percha filling techniques in vivo.

METHODOLOGY

Human teeth were randomly divided into two equal groups, with 30 canals each. The root canals were shaped by hand and ProFile 0.04 rotary instruments to size 20-40 at the end-point and then filled with gutta-percha cones and AH-Plus. In group A, a traditional warm vertical compaction technique was performed using the Touch'n Heat, and back-filling with the Obtura II. In group B, a modified warm vertical compaction technique was used: small amounts of gutta-percha were removed, and the remaining most apical 3 mm were compacted with a 1 mm movement; then thermomechanical back-filling was performed. The teeth were extracted, stored in dye, cleared, and the distance between the apex and apical limit of the filling, linear dye penetration, and voids were measured from the buccal, lingual, mesial and distal perspective. The homogeneity of variance and means was verified using Levene's test and t-test. ANOVA and Dunnett post hoc test were used to establish the significance and to analyse the effects through multiple comparisons.

RESULTS

Compared with the specimens of group A, the specimens of group B exhibited less mean linear dye penetration (P < 0.05), smaller void length (P < or = 0.05) and maximal width (P < or = 0.05) when examined in all four views, and a more precise filling when viewed from the buccal aspect (P < 0.05).

CONCLUSIONS

The modified warm vertical compaction technique with apical back-filling produced a more effective and precise three-dimensional filling.

A Comparison of Cohesive Strength and Stiffness of Resilon and Gutta-Percha

The purpose of this study was to compare the cohesive strength and stiffness of Resilon and gutta-percha under dry conditions and after 1 month of water storage to determine if they are stiff enough to reinforce roots. Dog-bone shaped specimens were created and pulled to failure at 3 mm/min in a Vitrodyne universal tester. The apparent modulus of elasticity, percent elongation, and yield stress were measured. Cohesive strength was defined as the yield stress. The data were analyzed using a two-way ANOVA for each outcome (alpha = 0.05). The results of this study show that the cohesive strength (that is the tensile stress when they begin to flow or break) and modulus of elasticity (or stiffness) of gutta-percha and Resilon are relatively low. Although the results showed statistically significant differences between the physical properties of gutta-percha and Resilon under varied conditions, these differences were not clinically significant. In conclusion, the stiffness of Resilon and gutta-percha is too low to reinforce roots after root canal therapy.

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.

In Vitro Infrared Thermographic Assessment of Root Surface Temperatures Generated by High-Temperature Thermoplasticized Injectable Gutta-Percha Obturation Technique

The aim of this in vitro study was to measure the temperature rises on the outer surface of roots produced by high-temperature thermoplasticized injectable gutta-percha technique. Thirty extracted human teeth with a single canal (15 maxillary central incisors and 15 mandibular central incisors) were used in this study. After root canal cleaning and shaping, the teeth were obturated with the injected gutta-percha heated to 160 degrees C (Obtura II). Temperature changes on the whole mesial outer surface of the roots was measured using an infrared thermal imaging camera. It showed that the use of gutta-percha heated to 160 degrees C to fill the maxillary central incisors and mandibular central incisors resulted in the rises of the root surface temperature by 8.5 degrees C and 22.1 degrees C, respectively. In conclusion, the injection of the gutta-percha heated to 160 degrees C into the root canal of maxillary central incisors produces temperature on the outer root surfaces below the theoretical critical level and, therefore, should not cause damage to supporting periradicular tissues. The injection of gutta-percha into the root canal space of the mandibular central incisors in vitro, resulted in an elevation of the root surface temperature by more than 10 degrees C.

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.

Interfacial Strength of Resilon and Gutta-Percha to Intraradicular Dentin

Strengthening of Resilon-filled roots via an adhesive interface should be reflected by improvement in the interfacial strength and dislocation resistance between the root fillings and intraradicular dentin. This study compared the interfacial strengths of Resilon/Epiphany and gutta-percha/AH Plus using a thin-slice push-out test design. Failure modes of root slices after push-out testing were examined with environmental scanning electron microscopy. The gutta-percha group exhibited significantly higher interfacial strength than the Resilon group, when premature failures that occurred in Resilon root slices were included in the statistical analysis. The gutta-percha root slices failed exclusively along the gutta-percha/sealer interface. The Resilon root slices failed predominantly along the sealer/dentin interface with recognizable, fractured resin tags. Detachment of the Resilon from the Epiphany sealer was also surprisingly observed in some specimens. The similarly low interfacial strengths achieved with both types of root filling challenges the concept of strengthening root-filled teeth with the new endodontic material.

Three Canal Mandibular First and Second Premolars: A Treatment Approach. A Case Report

Mandibular premolars have earned the reputation for having aberrant anatomy. The occurrence of three canals with three separate (type V, Vertucci) foramina in mandibular premolars is very rare. If one is to treat mandibular premolar teeth with three canals predictably, it is necessary to be aware of their clinical and radiographic anatomy. These teeth may also require special shaping and obturating techniques. This article reports and discusses the treatment recommendations for an unusual occurrence of three canals with three separate foramina in both the first and second mandibular premolars in the same patient.

Intracanal temperature rise evaluation during the usage of the System B: replication of intracanal anatomy

AIM

To evaluate and determine intracanal temperature rises at 2 and 4 mm from the working length (WL) necessary to obtain proper replication of intracanal anatomy with gutta-percha (GP) using the System B heat source during vertical condensation.

METHODOLOGY

A split-tooth model was prepared and artificial shallow depressions were cut in the buccal canal wall 2 and 4 mm from the WL. At the same level on the palatal wall holes were drilled to adapt two thermocouples. The canal was filled using GP in a vertical condensation technique by placing the System B plugger at 2 and 4 mm from the WL in groups A and B, respectively. Two control groups in which no GP was used were carried out placing the plugger 2 and 4 mm from the WL (groups A.c and B.c, respectively) and activating the heat source. Recording of temperature rise was carried out during the filling procedure for groups A and B and during activation for control groups A.c and B.c; the highest temperatures were recorded. After each filling was completed, 3 min were allowed for the GP to cool and the model divided to reveal the filling. Images of the GP were taken with a CCD camera to evaluate the presence of replication of artificial round depressions. In control groups, the temperature was recorded for 20 s after a 3 s activation of the heat source. The rise in temperature was compared between the groups individually at each level (2 or 4 mm) and statistically analysed using one-way anova and Fisher PLSD tests at 5% of significance level (P < 0.05).

RESULTS

Mean temperature rises of 14 +/- 3 and 12 +/- 2 degrees C at 2 and 4 mm from the WL, respectively, were observed in group A fillings, and 4 +/- 1 and 6 +/- 1 degrees C at 2 and 4 mm, respectively, in group B fillings. Recordings at 2 mm showed significantly (P < 0.05) higher temperature rises with group A.c when compared with groups B and B.c. Replication of intracanal anatomy with GP was always found in group A fillings at both levels but only 4 mm from the WL in group B fillings.

CONCLUSIONS

Positioning the plugger close to WL and a temperature rise of 6 degrees C were necessary to obtain replication of intracanal anatomy. A mean temperature rise of 4 degrees C at 2 mm from WL (group B) resulted in no replication of intracanal anatomy. Further studies simulating clinical conditions are necessary.