Evaluation of Effectiveness of Two Different Endodontic Retreatment Systems in Removal of Gutta-percha: An in vitro Study

AIM

To determine the effectiveness of two different endodontic retreatment systems for the removal of laterally compacted gutta-percha (GP).

MATERIALS AND METHODS

Sixty-three freshly extracted human maxillary central incisors were used for the study. The teeth were instrumented with K-flex files and obturated using lateral condensation technique with GP and AH Plus sealer. The teeth were divided into three retreatment groups, each group consisting of 21 teeth. Group I: D-RaCe desobturation files (D-RaCe); group II: ProTaper Universal retreatment files (PTUR); group III: Hedstrom files (H-file). After removal of GP, the teeth were split longitudinally and divided into three equal parts: Cervical, middle, and apical third. The middle and apical thirds of all root halves were examined using scanning electron microscope (SEM). The total surface area covered by the residual debris was evaluated using Motic Image plus 2.0 software. Statistical analysis was done by one-way analysis of variance (ANOVA) test with a p-value <0.05 used to determine significance and Tukey's multiple post hoc tests used for comparison between the groups, and 't' test was done for comparison between the thirds within the same group.

RESULTS

The PTUR retreatment files showed overall better performance compared with D-RaCe files and H-files. The PTUR files performed better at middle third compared with others. The PTUR files and D-RaCe files performed equally at apical third better than H-files.

CONCLUSION

ProTaper retreatment files are better compared with D-RaCe files and H-files for the retreatment of the previously endodontically treated teeth.

CLINICAL SIGNIFICANCE

Highest efficacy for the removal of GP was shown by ProTaper Universal System followed by D-RaCe and H-file.

Adaptation of gutta percha to oval canals: a cone beam computed tomographic analysis

This study evaluated the influence of different instrumentation techniques on the adaptation of gutta percha cones in oval-shaped root canals. A total of 90 human single-rooted teeth were divided into groups according to the instrumentation technique that was used: group M, manual; group OM, hybrid: oscillatory plus manual; group PT, rotary (ProTaper Universal); group OPT, hybrid: oscillatory plus rotary (ProTaper Universal); group MT, rotary (Mtwo); and group OMT, hybrid: oscillatory plus rotary (Mtwo). After a single gutta percha cone was adapted to the canal, cone beam computed tomography was utilized to perform assessments at areas of greater contact of gutta percha to root canal walls. The adaptation was rated as ideal, satisfactory, minimally acceptable, or unsatisfactory. The frequency of ideal adaptation of the cone to the 4 canal walls varied from 26.67% (groups OMT and PT) to 73.33% (group MT); the differences between group MT and groups PT and OMT were statistically significant (P < 0.05). The mean area of the canal preparation without adaptation (contact) of the cone varied from 0.06 mm² (group MT) to 0.41 mm² (group OMT). The results showed that an instrumentation technique using the Mtwo system provided the best adaptation of the .04 gutta percha cones to anatomically oval root canals.

A Comparative Volumetric Evaluation of Four Obturating Techniques in Primary Teeth Using Cone Beam Computed Tomography

PURPOSE

To compare the volume of root canals of primary teeth filled by four different obturating techniques: (1) lentulospiral (LS); (2) insulin syringe (IS); (3) endodontic pressure syringe (EPS); and (4) the NaviTip system (NS) using cone beam computed tomography (CBCT).

METHODS

76 root canals of primary posterior teeth were selected and divided into four groups, according to the obturation technique. Biomechanical preparation of each root canal was completed with a number 30 K-file, and the volumes of the canals were then measured using CBCT. Each canal was obturated with zinc oxide eugenol paste using the respective technique for that group. A second CBCT scan was performed to measure the filled volume in each canal, and the percentage of obturated volume (POV) was calculated.

RESULTS

A statistically significant difference was seen between the pre- and post-mean values (P<.001) and in the mean POV values (P< .001) among the four groups. NS (93.5 percent) and EPS (91.5 percent) showed the highest POV compared to LS (75.5 percent) and IS (64 percent).

CONCLUSION

The NaviTip system and endodontic pressure syringe showed the best root canal obturation, with the nearest to complete filling of the volumes of prepared root canals, while the insulin syringe was least effective.

Less extrusion debris during the retreatment of curved canals using twisted files with higher rotational speeds: an ex vivo study

BACKGROUND

Debris extrusion from the apical foramen can be problematic in severely curved canals. This study aimed to assess the use of Twisted Files (TF) at different rotational speeds during retreatment, compared with manual technique using Triple-Flex Files (TFF).

METHODS

Forty-eight mesiobuccal root canals were randomized to four groups (n = 12 per group). In groups A, B, and C, gutta-percha was removed using TF at 500, 1000, and 1500 rpm, respectively, while it was removed using TFF in group D. Apical debris was collected in a pre-weighed centrifuge tube. The weight of dry debris was assessed by comparing the pre- and post-instrumentation weight for each group.

RESULTS

Instrumentation in group D (0.69 ± 0.04 mg) extruded significantly more debris than any of the TF groups (A: 0.54 ± 0.05 mg; B: 0.48 ± 0.04 mg; C: 0.42 ± 0.03 mg; all P < 0.001). In addition, increasing the rotational speed of TF decreased the amount of extruded debris (A vs. B: P = 0.006; B vs. C: P < 0.001; A vs. C: P < 0.001).

CONCLUSIONS

TF at 1500 rpm produced less apical extrusion debris than other TF operating speeds and TFF.

The sealing ability of ProRoot MTA when placed as an apical barrier using three different techniques: an in-vitro apexification model

OBJECTIVE

To assess the sealing ability of ProRoot MTA when placed as an apical barrier using three different techniques.

METHOD AND MATERIALS

Sixty freshly extracted single-rooted human teeth were decoronated and standardized to a root length of 15 mm. The root segments were prepared with Gates Glidden burs to simulate a divergent open apex of immature teeth and randomly assigned into three experimental groups of 20 samples each. MTA (5 mm) was placed by pluggers (Group A), paper points (Group B), or ultrasonic tips (Group C). A cotton pellet moistened with saline was placed in the root canals till the material set, and the coronal portion was sealed with Cavit. After 24 hours, the Cavit and cotton pellet were removed and the canals dried and obturated with warm guttapercha (Obtura) and AH 26 sealer. Coronal portions of all samples were then sealed with Cavit. All root segments were double-coated with nail varnish except for the open apex and were exposed to methylene blue dye for 48 hours at room temperature. The samples were sectioned longitudinally (layer thickness 0.4 mm) and the extent of dye penetration was measured with a stereomicroscope (magnification 20×).

RESULTS

The mean depth (± standard deviation) of dye leakage for Group A was 1.34 ± 0.5 mm, Group B 1.25 ± 0.4 mm, and Group C 1.14 ± 0.4 mm. There were no significant differences among the three experimental groups (.178 < P < .552).

CONCLUSION

ProRoot MTA has a similar sealing ability when placed as an apical barrier with pluggers, paper points, or ultrasonic tips.

Modern Endodontic Principles. Part 5: Obturation

Once cleaning and shaping is complete the clinician must obturate the canal. There are many different materials and techniques available each with their own discrete advantages and disadvantages. Whichever technique is used, the goal is to seal the entire prepared length of the root canal. This paper describes how best this may be achieved. CPD/Clinical Relevance: It is incumbent on the clinician to ensure that once the canal has been prepared it is sealed from bacterial re-entry.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

[Real temperature of the continuous-wave pluggers]

OBJECTIVE

To measure the real temperatures on the pluggers of three continuous-wave devices, and to provide theoretical reference to evaluate thermal damage and heat's influence on the filling materials.

METHODS

The dual channel K type thermocouple was contacted to various sizes' pluggers in three different continuous-wave devices (BeeFill, Elements, B&L), and the highest temperatures at different points (tip, and 2 mm, 5 mm, 10 mm from the tip) of the pluggers (preset temperature was 200 °C) were recorded. The measurements were performed 5 times. T-test was used to compare the real temperatures at the tips with that set on the display and one-way ANOVA was used to compare the temperatures of the pluggers in different devices, sizes and points.

RESULTS

The highest temperature was at the tip of BeeFill 40/0.03 plugger (198.7±7.7) °C, but there was on statistical differences between that and the preset temperature 200 °C. The temperatures of the remaining pluggers were obviously lower than 200 °C (P<0.05). The lowest temperature of the pluggers was detected at 10 mm from the tip of BeeFill 60/0.06 plugger (69.9±4.0) °C. The highest temperature of each plugger was detected at the tip or 2 mm from the tip (112.1 to 198.7 °C,and the median was 140.8 °C).

CONCLUSION

The real temperature of most continuous-wave pluggers included in this study is below the set temperature 200 °C.

Comparison of retreatment ability of full-sequence reciprocating instrumentation and 360° rotary instrumentation

OBJECTIVES

The purpose of the present study was to investigate the amount of root canal filling material after root canal filling removal with 360° rotary instrumentation or reciprocating motion with the same file sequence.

MATERIALS AND METHODS

Root canals of the 36 mandibular premolars were shaped with ProTaper Universal instruments up to size F2 and filled with corresponding single gutta-percha cone and sealer. The teeth were assigned to two retreatment groups (n = 18): group 1 360° rotational motion and group 2 reciprocating motion of ATR Tecnika motors (1310° clockwise and 578° counterclockwise). Retreatment procedure was performed with ProTaper Universal retreatment files with a sequence of D1-3 and ProTaper Universal F3 instruments. Total time required to remove filling material were recorded. Remaining filling material was examined under stereomicroscope at ×8 magnification. The data were analysed statistically using the Mann-Whitney U test, and testing was performed at 95 % confidence level (p < 0.05).

RESULTS

There were no significant differences between the groups (p > 0.05) in terms of remaining filling material. The total time required for retreatment was shorter in 360° rotational motion group compared to reciprocating motion group (p < 0.05).

CONCLUSION

Both continuous rotation and reciprocating motion showed similar effectiveness in terms of root canal filling material removal.

CLINICAL RELEVANCE

Using ProTaper Universal retreatment instruments with reciprocating motion of ATR motor and conventional rotary motion have similar efficacy in root canal filling removal.

Treatment time for non-surgical endodontic therapy with or without a magnifying loupe

BACKGROUND

Use of magnifying loupe may increase the efficiency of dental care. This clinical trial compared the time in performing non-surgical endodontic therapy with or without the use of a magnifying loupe.

METHODS

Patients who required primary endodontic treatment in clinical trial centres at the University of Hong Kong (HKU) in Hong Kong and Peking University (PKU) in Beijing were invited to participate in this study. Two HKU dentists and 2 PKU dentists, forming 2 pairs of dentists with similar years of clinical experience, performed endodontic treatments according to the same procedures and used the same materials, either in single or multiple visits. They had no prior experience with the use of a magnifying loupe. One dentist from each pair was trained to use a magnifying loupe (x2.5). The treatment time was recorded.

RESULTS

Eighty-four PKU patients with a mean age of 42.8 years and 98 HKU patients with a mean age of 46.0 years were recruited in this study. Ninety-six teeth were treated with a magnifying loupe and 86 teeth were treated without a magnifying loupe. The results showed that treatment time was not associated with age, gender, tooth vitality, or the presence of apical radiolucency or sinus tract. The results of ANCOVA revealed the treatment time was associated with the clinic (HKU or PKU), root canal system (single or multiple), presence of preoperative pain, treatment visit (single or multiple), the use of a magnifying loupe, and the experience of the operator.

CONCLUSION

In this study, the use of a magnifying loupe could significantly reduce the endodontic treatment time.

TRIAL REGISTRATION

Clinical Trials ChiCTR-IOR-15005988 registered 15 February 2015.

Effect of a two-step placement procedure on the dislocation resistance of a methacrylate resin-based root canal sealer: a proof of concept

PURPOSE

To investigate whether the placement of a methacrylate root canal sealer or a conventional epoxy root canal sealer in two steps increases their dislocation resistance when compared to a one-step placement procedure.

MATERIALS AND METHODS

Eighty single-rooted teeth were randomly allocated to 4 groups (n=20). All canals were instrumented to size 40, 0.06 taper and irrigated according to a standardized protocol. Root canal filling was conducted as follows: group 1: methacrylate sealer placed in two steps; group 2: methacrylate sealer placed in one step; group 3: epoxy sealer placed in two steps; group 4: epoxy sealer placed in one step. After setting, thin slices at different root levels were obtained and submitted to push-out testing. RESULTS were analyzed with non-parametric tests to compare the two-step procedures to their one-step counterparts. Failure modes were determined by stereomicroscopy. Random untested methacrylate sealer specimens were also examined with scanning electron microscopy.

RESULTS

At each root level, dislocation resistance was significantly higher for the two-step procedure than for the one-step procedure using the methacrylate sealer (p=0.003, p=0.005, p<0.001) but not the epoxy sealer (p=0.83, p=0.1, p=0.06). Among root levels, there were no significant differences in dislocation resistance in the methacrylate sealer two-step group, while all other groups showed differences.

CONCLUSION

A two-step placement procedure resulted in significantly higher dislocation resistance for the methacrylate sealer but not for the epoxy sealer.

Comparison of vertical forces during root canal filling with three different obturation techniques

The aim of this study was to examine and compare vertical forces exerted during root canal obturation with the cold lateral condensation technique, Thermafil technique and ProTaper guttapercha. Fourty-five single-rooted permanent teeth were used in the study. All specimens were instrumented using the ProTaper rotating technique and were randomly divided into three experimental groups (n = 15 per group). In the first group, root canals were obturated using the cold lateral condensation technique. In the second group, the Thermafil technique was used to obturate root canals. In the last group, a ProTaper gutta-percha of the same taper as the instrumented root canals was used for root canal obturation. Vertical forces were measured using the device developed for simulation of endodontic treatment. The results showed a statistically significant difference (p = 0.0001) for vertical forces when cold lateral condensation obturation technique was used in comparison to other techniques. No statistically significant difference was found for vertical forces during obturation with Thermafil and ProTaper gutta-percha (p = 0.16). The cold lateral condensation technique exerted higher vertical forces in comparison to the Thermafil and ProTaper obturation techniques.

Clinical efficacy of various root canal obturating methods in primary teeth: a comparative study

AIM

The purpose of this in vivo study was to evaluate and compare the efficacy of different obturating methods used in primary teeth, when obturated using a combination of zinc oxide and iodoform paste (Endoflas F.S.).

MATERIALS AND METHODS

A group of 29 patients aged 3-9 years and a total of 64 teeth were selected. These 64 teeth (32 anterior teeth=32 canals, and 32 posterior teeth=80 canals) were randomly divided into 4 groups. Teeth were obturated with Lentulo spiral, pressure syringe, bi-directional spiral and Pastinject. Post-operative evaluation was done for: quality of canal obturation, (underfilled, optimally filled, overfilled) and presence of voids.

RESULTS

Pastinject exhibited the highest number of optimally filled canals, while the highest number of underfilled canals were observed with bi-directional spiral, and the highest number of overfilled canals were observed with pressure syringe. A minimum number of voids was present in canals filled with the Pastinject technique and pressure syringe.

CONCLUSION

These results suggest that Pastinject was the most effective technique for obturation of primary teeth.

Comparison of different obturation techniques for primary molars by digital radiography

PURPOSE

The purpose of this study was to compare six methods of root canal filling in primary mandibular second molars via digital radiography.

METHODS

A total of 239 canals were prepared and obturated with zinc-oxide eugenol paste. Obturation methods compared were: anesthetic syringe; NaviTip syringe; pressure syringe; tuberculin syringe; lentulo spiral; and packing with a plugger. The canals were evaluated in photostimulated phosphor radiographs for length of obturation, presence of voids, and number and sum of void sizes. The data were analyzed using chi-square, Kruskal-Wallis and Mann-Whitney tests.

RESULTS

There were significant differences between all groups in the length of obturation (P>.01) and presence of voids (P<.001). The lentulo and tuberculin syringe groups, respectively, showed the best and worst results for length of obturation. Significant differences were also found in the number of voids (P<.001) and mean sum of void sizes in the coronal (P<.001) and middle third (P=.003). For the number and size of the voids, the NaviTip group showed the best results.

CONCLUSION

Lentulo produced the best results in terms of length of obturation, while NaviTip syringe produced the best results in controlling paste extrusion from the apical foramen and having the smallest void size and lowest number of voids.

Rational endodontics must pass the commonsense test

By applying the principles of common sense, we can arrive at a rational approach to endodontics that eliminates concerns we have in using the rotary NiTi. We can use this same approach to improve our choices of what to use to create the original glide path. By switching from the poorly designed K-file to the more rationally designed and utilized relieved reamers, we not only create a more usable glide path, we quickly learn that an extension of this approach can eliminate the use of rotary NiTi and the various compromises it makes us incorporate in an attempt to use it safely.

In vitro comparative study of the microbial leakage of one-step, thermafil and lateral condensation techniques

AIM

To compare the apical seal of lateral condensation technique, thermafil and one-step by using this model.

MATERIALS AND METHODS

A two-chamber bacterial microleakage model using E. faecalis as microbial marker was used for evaluation of the leakage. Bacterial penetration was monitored over a 60-day period. Leakage was recorded when turbidity was observed in the lower chamber.

RESULTS

After comparing the bacterial penetration values, total penetration was observed 45% in lateral condensation technique, 80% in thermafil and 75% in one-step. There was no significant difference between groups after 60 days; however, the microleakage in lateral condensation group was seen later than one-step and thermafil.

CONCLUSION

Thermafil and one-step obturator can be advocated as effective obturation techniques for achieving predictable success in endodontic therapy.

CLINICAL SIGNIFICANCE

Thermafil and one-step obturator are suitable devices for obturation.

Assessment of the tip surface of gutta-percha cones after different cutting methods

The surface of gutta-percha cones was evaluated after using five different cutting methods, including a new TipSnip device. The gutta-percha cones were cut off using: 1) TipSnip, 2) a single cut with a scalpel blade using a gauge, 3) two cuts with a scalpel blade using a gauge, 4) a razor blade against a glass slab or 5) scissors. Samples were examined under stereomicroscopy and observed by three highly qualified evaluators. The Kappa coefficient with a 95% confidence interval was used and all scores were tabulated and analyzed statistically using a nonparametric Kruskal-Wallis test with a 5% significance level. Cutting with scissors produced significant irregularities in the cone surface, providing the worst result. TipSnip, two cuts with scalpel blade, and cut with a razor against a glass slab provided the best results. A regular surface on the tips of gutta-percha cones improves apical fit, and may be achieved by means of different cutting methods.

Comparison of the single cone and cold lateral compaction techniques in sealing 0.04 taper root canal preparations

This study compared the coronal sealing ability of three different combinations of obturation materials and techniques after root canals were prepared with 0.04 taper nickel titanium (NiTi) rotary instruments. This study utilized three experimental groups: Group 1 was obturated with 0.02 taper gutta-percha cones and AH 26 sealer cement, using the cold lateral compaction technique; Group 2 was obturated with 0.02 taper Resilon cones and Epiphany sealer, using the cold lateral compaction technique; and Group 3 was obturated with 0.04 taper Resilon cones and Epiphany sealer, using the single cone technique. Coronal microleakage was evaluated using dye penetration methodology. Microleakage results showed that the single cone Resilon obturation technique showed significantly more linear dye penetration than Resilon or gutta-percha subjected to cold lateral compaction. There was no significant difference between gutta-percha and Resilon when the cold lateral compaction technique was used. The results of this study suggest that the single cone Resilon obturation technique is inferior to cold lateral compaction of Resilon or gutta-percha.

The quality of root canal preparation and root canal obturation in canals treated with rotary versus self-adjusting files: a three-dimensional micro-computed tomographic study

AIM

The study was designed to quantitatively evaluate the quality of root canal preparation and root canal obturation in canals treated with either rotary or self adjusting files, using three-dimensional micro-computed tomographic (CT) analysis.

METHODOLOGY

Pair-matched root canals were instrumented with either rotary nickel-titanium files or self-adjusting files following the manufacturers' instructions. The area of the canal wall unaffected by the preparation procedure was analyzed using before and after micro-CT images. Root canal obturation was done using lateral compaction with gutta-percha and AH26 (Dentsply-DeTrey, Konstanz, Germany). Teeth were scanned a third time, and the adaptation of the filling material to the canal walls was evaluated three-dimensionally by micro-CT analysis and the area of canal wall untouched by the filling was determined. The correlation between these two parameters within each of the groups was studied using the Pearson correlation test.

RESULTS

A high percentage of unaffected root canal walls (60% +/-14%) and areas untouched by the root canal filling (45% +/- 15%) were found in canals treated with rotary files. Both parameters were significantly smaller in canals treated with self-adjusting files (17% +/- 9% and 17% +/- 11%, respectively) (p < 0.01). No correlation was found between these parameters within each of the groups.

CONCLUSION

Within the limitations of the present study, the self-adjusting files allowed better cleaning and shaping and better adaptation of the root canal filling than those allowed by rotary files.

Outcome of root canal treatment using Soft-Core and cold lateral compaction filling techniques: a randomized clinical trial

AIM

The purpose of this clinical and radiographic investigation was to evaluate the treatment outcomes of endodontically treated teeth obturated with Soft-Core versus cold lateral compaction.

METHODS AND MATERIALS

A total of 98 teeth were endodontically prepared using the Quantec LX rotary system with a crown-down pressureless technique and obturated with either Soft-Core or cold lateral compaction. The outcome of treatments were evaluated clinically and radiographically by two blinded evaluators after three years. Statistical analysis was performed using an unpaired t-test and the Mann Whitney test at the level of significance set at 95%.

RESULTS

Regardless of the periapical status of the teeth, no statistically significant difference was found between the two obturation techniques (p > 0.05). The Kappa value for the interobserver agreement was 0.73.

CONCLUSION

Within the limits of the study, it is concluded the Soft-Core obturation technique did not result in a significantly different treatment outcome when compared with cold lateral compaction after three years. Further investigations should be carried out on the Soft-Core technique.

CLINICAL SIGNIFICANCE

Using the Soft-Core system reduced working time, and the difference was found to be statistically different (p = 0.00056) from the working time required for cold lateral compaction. This reduction in canal filling time holds the potential for cost savings for clinicians while maintaining the quality of the clinical outcome.

Microleakage of human saliva in coronally unsealed obturated root canals in anaerobic conditions

The purpose of this study was to determine the time required for anaerobic bacteria in natural human saliva to contaminate root-filled teeth. Thirty-two single-rooted teeth were cleaned, shaped, filled, and exposed to human saliva for 120 days. Teeth that had not leaked were subjected to polymerise chain reaction examination. Sixty-six percent of the experimental group were totally contaminated. A PCR examination revealed there was no contamination in the apical 3 mm of leakage-free teeth.

Assessment of the accuracy of two gutta-percha gauges used to alter gutta-percha tip diameter

This study sought to compare the accuracy of two gauges used to alter gutta-percha (GP) cone tips. Randomly selected size 20 cones (with tapers of 0.02, 0.06, 0.10, or 0.12) were trimmed to size 50 (N= 10/taper/gauge) for an overall sample of 80 cones. Accuracy of the altered cone tips was determined by calculating the difference (in %) between the altered tip diameter and the expected tip diameter (0.50 mm). A two-factor ANOVA revealed significant differences (p < or = 0.05) in altered tip accuracy as a result of GP gauge and cone taper. The results suggest that the SybronEndo gauge performs accurately regardless of the cone taper, while the Maillefer gauge was accurate only when used to alter cones with a 0.02 taper.

Obturation with heat and vibration: the DownPak device

Achieving successful endodontic treatment requires an accurate diagnosis and appropriate cleaning, shaping, and three-dimensional obturation of the canals. This article describes a new obturation technique that utilizes a warm plugger or spreader, delivered (in conjunction with vibration) with a single cordless device, the DownPak.

[Periapical microleakage of root canals filled with four kinds of sealers using two obturation techniques]

OBJECTIVE

To study the periapical microleakage of the root canals filled with four kinds of sealers using two obturation techniques.

METHODS

Sixty-four extracted first maxillary premolars were randomly divided into four groups. All the root canals were prepared with Protaper rotary instruments and filled with two obturation techniques: warm vertical condensation and cold lateral condensation. Four kinds of sealers included: Cortisomol, nano-zinc oxide, Apexit and calcium hydroxide which were individually used for four groups. After the teeth were dyed for 7 days with Indian ink, dyeing lines were measured with digital camera under steromicroscope to reflect the microleakage.

RESULTS

In cold lateral condensation groups, dyeing lines of calcium hydroxide group had an average length of (1.75+/-0.22) mm, which was significantly longer than that of Cortisomol group (1.40+/-0.15 mm) and nano-zinc oxide group [(1.56+/-0.25) mm, P<0.05], while that of Apexit group showed to be the shortest one [(1.26+/-0.21) mm, P<0.05]. Dyeing lines of each warm vertical condensation group showed similar length [(0.97+/-0.13) mm to (1.07+/-0.15) mm, P > 0.05], which were significantly shorter than that of cold lateral condensation groups (P<0.05).

CONCLUSION

The gradients and dosage of sealers showed significant influences on periapical microleakage of root canals filled using cold lateral condensation technique. Warm vertical condensation technique could dramatically eliminate periapical micro-leakage of root canals, irrespective of the sealers used.

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.

Instrumentation and obturation of the apical third of root canals: addressing the forgotten dimension

Modern developments in instrument design and obturation techniques have greatly improved the efficiency of conventional endodontic therapy. Nickel titanium rotary instruments allow the practitioner to prepare canals more quickly and predictably. However, apical preparations by such instruments fail to address the anatomical complexity of the root canal system. Morphologic studies consistently show that canals are mostly oval or irregular in shape; therefore, round preparations by instrumentation result in uninstrumented areas of the root canal system. This is of particular importance in the apical third and in cases of preexisting periapical pathology, where residual bacteria may reside and cause persistent infections. How beneficial are these new instrumentation and obturation techniques to the basic purpose of root canal therapy in eradicating bacteria? This article presents the shortcomings of current instrumentation and obturation techniques and offers possible solutions to improve the outcome of endodontic therapy.

Ultrasonics in endodontics: a review of the literature

During the past few decades endodontic treatment has benefited from the development of new techniques and equipment, which have improved outcome and predictability. Important attributes such as the operating microscope and ultrasonics (US) have found indispensable applications in a number of dental procedures in periodontology, to a much lesser extent in restorative dentistry, while being very prominently used in endodontics. US in endodontics has enhanced the quality of treatment and represents an important adjunct in the treatment of difficult cases. Since its introduction, US has become increasingly more useful in applications such as gaining access to canal openings, cleaning and shaping, obturation of root canals, removal of intracanal materials and obstructions, and endodontic surgery. This comprehensive review of the literature aims at presenting the numerous uses of US in clinical endodontics and emphasizes the broad applications in a modern-day endodontic practice.

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.

Root Canal Retreatment

Root canal therapy is not always successful and an increasing number of patients are requesting retreatment to address intraradicular infection. The armamentarium available to assist the dentist, some of which is described in this article, has never been greater.

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.

Influence of the length of instrumentation and canal obturation on the success of endodontic therapy. A 10-year clinical follow-up

PURPOSE

To clinically test the periapical healing of the method of recurrent electronic root canal measurement and the method of root canal obturation by the guttapercha-eucapercha method.

METHODS

During 10 years of endodontic practice of the first author, endodontic interventions were performed on approximately 4500 patients, aged 12-75 years. The success of therapy was followed-up in 257 teeth with diagnosis K04.0 to K04.5 (according to the X international classification of diseases) for whom a preoperative and control radiograph during the investigation period existed. Root canal preparation started with the "crown-down pressureless technique" and proceeded with the method of recurrent electronic root canal measurement. Obturation was done by the guttapercha-eucapercha method up to the apical constriction.

RESULTS

The result of therapy success was approximately 95% overall (t-test, ANOVA); for the diagnosis: necrosis and pulp gangrene (K04.1): 64%; for the acute apical periodontitis (K04.4): 88%; for the inflamed pulp (K04.0) and pulp degeneration (K04.2) 95%; chronic apical periodontitis (K04.5): 98%, and abnormally formed hard tissue in the pulp (K04.3):100%.

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.

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 Quantitative Comparison of the Fill Density of MTA Produced by Two Placement Techniques

This study compared the fill density of mineral trioxide aggregate (MTA) produced by hand condensation with that produced by hand condensation with indirect ultrasonic (US) activation. Sixty acrylic blocks with straight or curved canals were instrumented to an apical size 45, and weighed with a digital electronic balance. In 30 randomly chosen specimens, the canal was filled with MTA by hand condensation and weighed. The MTA was removed; the canal was rinsed and dried, and refilled using hand condensation with indirect US activation. In the other 30 specimens, the procedure was carried out identically but in reverse order. The blocks were then reweighed. The weight of the MTA fill produced by the two placement methods in the two canal configurations was analyzed by a two-way ANOVA. Hand condensation with indirect US activation resulted in an MTA fill that was statistically significantly heavier, and thus denser, than that accomplished by hand condensation alone in both curved and straight canals (p < 0.0001).

Delivery of calcium hydroxide: comparison of four filling techniques

This study compared the weight and radiographic appearance of Ca(OH)(2) delivered into standardized, minimally and fully prepared canals using (a) an injection system, (b) an endodontic Flex-O file rotated counter-clockwise, (c) a lentulo spiral, and (d) a .04 rotary NiTi file rotated in reverse. Two extracted human second mandibular premolars with single canals were prepared to an MAF #25 or an MAF #40. A weight measurement and radiograph were made for each filling. Three independent examiners evaluated the radiographs. Regardless of technique, only about 45% of the optimal weight of Ca(OH)(2) was delivered into the minimally prepared canal. Radiographically the filling quality was only 1 to 2 (10 scale). In contrast, all delivery techniques delivered near optimal weight of Ca(OH)(2) in the completely prepared canal with a radiographic filling quality of 8.8 to 9.3. The results indicate that complete instrumentation is needed to obtain near optimal delivery of Ca(OH)(2).

Leakage resistance of the InnoEndo fiber obturation system

To ensure long-term function, endodontic restorations require proper sealing of the root canal system. Recent studies have recognized that microleakage in endodontically treated teeth has negative consequences (ie, apical migration of bacteria) on their prognosis, often resulting in failure. Findings in the dental literature suggest that the innovative technology, consisting of fiber-based obturation and adhesive obturation materials, can minimize this leakage. As demonstrated in this article, the ability to achieve an adequate marginal seal represents a significant advance in endodontic therapy.