Obturation of the root canal system

With all the technology that has been introduced in endodontics, there are now several ways to instrument and obturate root canals. Practitioners often develop their own "hybrid" technique after sharing ideas with several colleagues. The purpose of this article is to describe a technique of obturation, hoping that others may incorporate some aspects into their own "hybrid" style.

Perforation repair and one-step apexification procedures

As with any dental treatment, procedural mishaps can occur during root canal therapy. One such occurrence is the perforation of a root or pulpal floor. After a perforation occurs, the goals are to "sterilize" (decontaminate) the site and then seal the perforation. The material most widely used in endodontics to seal perforations is mineral trioxide aggregate (MTA). MTA us extremely biocompatible, and it has been shown historically that osteoidlike material grows right into MTA. The technique of one-step apexification offers an alternative to draw-out cases with several medicament-changing appointments that often result in a failed attempt at root-end closure. With the favorable histologic response of MTA, this material is the best current choice for this procedure. Completion of these cases in an effective and efficient way allows for permanent restorations to be done in a more timely manner, prolonging the longevity of these teeth.

Comparison of Spreader Penetration During Lateral Compaction of .04 and .02 Tapered Gutta-percha

The purpose of this study was to compare the initial penetration depth of fine-fine nickel-titanium (NiTi) and fine-fine stainless-steel (SS) spreaders during lateral compaction of .02 or .04 tapered master gutta-percha cones and to evaluate the effect of increasing canal curvature on penetration depth. Fifty-one root canals were instrumented to a standardized size and grouped by degree of curvature for comparison. Our results showed that NiTi spreaders penetrated to a significantly greater depth than SS spreaders using .02 tapered gutta-percha in canal curvatures greater than 20 degrees and when using .04 tapered gutta-percha regardless of canal curvature. No significant difference occurred between NiTi and SS-spreader penetration using .02 tapered gutta-percha in canal curvatures of 0 to 20 degrees (p > 0.05). Both NiTi and SS spreaders penetrated to a greater depth as canal curvatures increased to greater than 20 degrees (p < 0.05). Both NiTi and SS spreaders penetrated to a shallower depth with .04 tapered gutta-percha compared with .02 tapered gutta-percha (p < 0.0001).

Comparison of MicroSeal and System B/Obtura II obturation techniques

AIM

To compare the proportion of gutta-percha, sealer and voids following the filling of simulated root canals in plastic blocks using two warm gutta-percha techniques.

METHODOLOGY

Ten simulated root canals in plastic blocks were prepared using System GT Rotary Files and a.02 taper size 40 Quantec rotary nickel-titanium instrument and then filled with MicroSeal and Kerr EWT sealer. A further 10 simulated canals were prepared solely with System GT Rotary Files and obturated with System B/Obtura II and Kerr EWT sealer. All blocks were sectioned at 1 mm intervals. The sectioned root fillings were photographed through a stereomicroscope and the resultant slides scanned. The images were analysed using adobe photoshop 6.0 to give the proportions of gutta-percha, sealer or void at each level. The data were analysed using unpaired Student's t-test and Mann-Whitney U-test.

RESULTS

The MicroSeal technique produced a dense homogeneous gutta-percha fill at the apical 1 and 2 mm levels similar to the System B/Obtura II technique, but further coronally the sealer became mixed into the MicroFlow gutta-percha producing a heterogeneous mass with significantly less (P < 0.05) solid gutta-percha in the root filling compared to System B/Obtura II. The MicroSeal technique generally had more pooling of cement than the System B technique, however, this was only significantly different (P < 0.05) at the 4 mm level. The System B/Obtura II obturation gave an average of 99.27% +/- 1.09 gutta-percha fill at all levels.

CONCLUSIONS

The MicroSeal technique produced a heterogeneous fill consisting of the MicroFlow Master Cone and gutta-percha from the MicroFlow Cartridge mixed with sealer. The System B/Obtura II technique produced a homogeneous fill at all levels.

Clinical and Radiographic Evaluation of Root-canal Obturation with Obtura II

This study evaluated clinical and radiographic healing of 236 root-canal treatments in 131 cases obturated with the Obtura II system. One operator performed all canal preparation and obturation with sealer. A standardized apical-coronal preparation technique instrumented all canals. Clinical symptoms, periodontal condition, and radiographic findings were evaluated at 3, 6, and 12 months. Radiographs taken immediately postobturation were compared to recall radiographs. The level of the final root filling was classified as short (more than 2 mm short of the apex), flush (within 2 mm), or over (beyond) in 12.7%, 81.4%, and 5.9% of cases, respectively. More than 96% of cases were treated successfully by the Obtura II system. Where roots were filled flush, over, or short, lesions healed in 97%, 93%, and 93% of cases, respectively, with no significant differences (p < 0.05). Root filling excess had no impact on the healing process.

Effect of different temperatures and penetration depths of a System B plugger in the filling of artificially created oval canals

OBJECTIVES

The purpose of this study was to compare the gutta-percha-filled area in oval canals while varying the temperature and penetration depth of the System B plugger.

STUDY DESIGN

Seventy-five resin blocks, with artificially created oval canals, were obturated by using a continuous wave technique. In groups 1, 2, and 3, the plugger was introduced to a depth of 4 mm from the apex at set temperatures of 100, 200, and 350 degrees C, respectively. In group 4, the plugger was inserted to a depth of 2 mm from the apex at a set temperature of 200 degrees C. Group 5 was obturated in the same way as group 2, and then an additional cold plugging was performed to a depth of 3 mm from the apex. The cross sections of the obturated canals were photographed, and the percentage of the gutta-percha-filled area (PGP) was measured.

RESULTS

No significant differences were found between the 3 different temperature settings (P >.05). At 1 mm from the apex, group 4 showed the highest PGP (95.57% +/- 6.86), followed by group 5 (84.72% +/- 12.19), and group 2 (67.33 +/- 13.03) (P <.05).

CONCLUSION

In artificially created oval canals, plugger temperature within the range used in this study did not affect the PGP. However, the penetration depth of the plugger was significantly related to PGP.

In vitro infrared thermographic assessment of root surface temperature rises during thermafil retreatment using system B

The purpose of this in vitro study was to measure the temperature rise on the outer root surface during retreatment of Thermafil using the System B HeatSource. Twenty extracted human maxillary premolars were filled with Thermafil with plastic carriers and divided into two groups of 10 teeth each. In group 1, Thermafil obturators were retrieved using System B HeatSource fitted with a medium plugger at a temperature of 225 degrees C. The plugger was placed first on the buccal, then on the lingual of the plastic carrier for 5 s each. This melted the gutta-percha and softened the plastic carrier. In group 2, Thermafil obturators were retrieved in the same manner except that the heated plugger was placed for 8 s. The temperature changes on the outer root surfaces were recorded using a thermal imaging camera. Thermafil retreatment in vitro using a System B HeatSource causes temperature rises ranging from 26.7 degrees C to 46.0 degrees C. This finding could possibly have implications for creating injury of the periodontal tissues.

Contemporary concepts in endodontics: 2003 and beyond

Recent changes have made it possible to perform endodontic treatment more efficiently, with improved precision and greater patient acceptance. This article reviews these various concepts and highlights how endodontics now can be performed with enhanced abilities and clinical results.

In vitro evaluation of apical microleakage following canal filling with a coated carrier system compared with lateral and thermomechanical Gutta-Percha condensation techniques

AIM

The apical sealing ability of a coated carrier system was evaluated in extracted human teeth and compared with lateral and thermomechanical condensation techniques using dye penetration.

METHODOLOGY

Sixty-four extracted single-rooted teeth were instrumented to an apical size 30 using 4% taper Hero 642 trade mark instruments (Micromega, Besançon, France). The sample was divided into three experimental groups. Twenty teeth were randomly obturated with lateral condensation, 20 with thermomechanical compaction and 20 teeth with the Herofill trade mark Soft-Core system. Four teeth were used as positive and negative controls. The teeth were covered with nail varnish up to 2 mm from the apical foramen and immersed in a 2% aqueous methylene blue dye solution for 1 week and then washed, dehydrated and embedded in resin. The apical 1 mm of each tooth was removed to reveal the apical limit of the preparation. Transverse sections of the teeth were taken at 500, 1000 and 1500 micro m from this point and evaluated for apical leakage. Significant differences between the preparations were analysed with a semiautomatic analyser and the ratio of the dye-penetrated surface to the total dentinal surface was calculated.

RESULTS

Statistical analysis of the results demonstrated significantly less leakage for the Herofill trade mark Soft-Core system compared to lateral condensation in terms of total mean dentinal surface and at the 500 micro m level. No other differences were noted between Herofill trade mark Soft-Core and thermomechanical or lateral condensation, either for the total mean value or at each level.

CONCLUSIONS

The Herofill trade mark Soft-Core system was a reliable obturation system in the apical portion and compared favourably with other gutta-percha filling techniques.

A two-and-a-half year perspective on simplified endodontic techniques

Simplified Endodontic Techniques (SET), along with EZ-Fill, a bidirectional spiral and epoxy root canal cement, have been used for more than 2 1/2 years. This particular sequence of instrumentation and obturation provides the dentist with predictable and easily attained success. Periapical areas demonstrate healing, and excess EZ-Fill cement is resorbing. Postoperatively, patients experience approximately 80% less pain in both occurrence and intensity. The adoption of SET, along with EZ-Fill, allows dentists to significantly increase their productivity while dramatically improving the quality of their work.

A comparison of fill density obtained by supplementing cold lateral condensation with ultrasonic condensation

The purpose of this study was to compare quantitatively the density of gutta-percha root canal fillings produced by cold lateral condensation with those produced by an ultrasonically energized spreader in a warm lateral condensation technique in artificial root canals. Thirty-degree simulated root canals in 30 transparent acrylic blocks were instrumented by using rotary files. The blocks were weighed. The canals were obturated with gutta-percha using cold lateral condensation without sealer and then weighed again. Two applications of warm lateral condensation were then performed on the same 30 canals using the UES. The blocks were weighed once more after each additional UES obturation treatment. The first heat application produced a 26.92% increase in weight over lateral condensation, and the second heat application produced an additional 5.95% increase. A one-way repeated measures ANOVA followed by the Tukey-Kramer test revealed that both applications of warm lateral condensation produced significant (p < 0.001) increases in weight. Results indicate that warm lateral condensation using a ultrasonically energized spreader results in denser gutta-percha fills by weight than cold lateral condensation.

Effect of three different sealers on the sealing ability of both thermafil obturators and cold laterally compacted Gutta-Percha

The purpose of this study was to assess the seal obtained in straight and curved root canals filled with either laterally compacted gutta-percha or Thermafil obturators. Each technique was used in combination with three different sealers (RSA RoekoSeal, AH Plus, AH 26). Thermafil obturators were also used without sealer, resulting in a total of 14 test groups of 16 teeth each. Sixty teeth served as positive or negative controls. Included in the study were 142 extracted teeth with straight and 142 with curved root canals. All canals were enlarged up to size 40. After obturation, all roots were placed in India ink for 48 h and rendered transparent to measure the maximum linear dye penetration. Canals filled with Thermafil obturators had significantly more extrusion of filling material than canals filled by lateral compaction (p < 0.01). Thermafil without sealer showed significantly greater dye penetration compared with all other groups both in straight and in curved canals (p < 0.05). As long as a sealer was used, the seal obturated with Thermafil was equivalent in terms of dye penetration to lateral compaction. There were no statistical differences in the mean apical dye penetration among the three sealers. The differences between the dye penetration in straight and in curved canals were insignificant for all groups (p > 0.05). Under the conditions of this study, Thermafil obturators achieved seals comparable to lateral compaction, as long as a sealer was used.

Temperature change within gutta-percha induced by the System-B Heat Source

AIM

This study evaluated the temperature change within gutta-percha during the vertical compaction technique performed with a System-B Heat Source.

METHODOLOGY

Extracted human teeth were prepared and divided in two equal groups depending on the apex diameter (group 1: 0.20-0.25 mm and group 2: 0.30-0.35 mm). Teeth were root treated with a combination of step-back and coronal flaring instrumentation using Gates Glidden burs and hand stainless steel K- and H-files. Two thermocouples were connected to the outer surface of the root: the first one was placed 2 mm apically from cement-enamel junction (CEJ) (point C); and the second one 1.5 mm from the apex (point A). The instrumented canals were filled with size F gutta-percha cones. All teeth were then immersed in a thermostatic bath at a constant temperature of 37 degrees C and warm vertical compaction was performed using a System-B Heat Source. delta T values were recorded by means of a digital thermometer connected to the thermocouples.

RESULTS

Increments of temperature (delta T) recorded in point A revealed a mean value of 0.5 +/- 0.5 degree C for group 1 and 0.9 +/- 1.1 degrees C for group 2; delta T values recorded at point C gave a mean value of 4.1 +/- 1.7 degrees C for group 1 and 3.9 +/- 1.81 degrees C in group 2. No statistical difference was found between the groups, whilst a difference was present between the measurements at points A and C (P < 0.01).

CONCLUSIONS

The use of the System-B Heat Source on root canals maintained at a constant body temperature by a thermostatic bath revealed that the increase of temperature of the gutta-percha at the apical third of the canal was negligible and that the compaction of the mass of the gutta-percha close to the apex was performed at body temperature. Minor changes in temperature of the outer surface of the root canals occurred, suggesting no danger for the periradicular tissues.

Influence of microbrush on efficacy of bonding into root canals

PURPOSE

Recently, several 'one-bottle' systems have been introduced for bonding into root canals. This study evaluated the influence of two brushes used as carriers of a primer-adhesive solution in the formation of resin tags, adhesive lateral branches and hybrid layer when used to bond fiber posts.

MATERIALS AND METHODS

Twenty root canal treated teeth, extracted for periodontal reasons, were selected for this study. The samples were randomly divided into two groups of 10 samples each: Group 1: Microbrush + One Step + Dual Link resin cement; Group 2: One Step + Dual Link resin cement. The adhesive system and resin cement were used strictly following manufacturers' instructions. The priming-adhesive solution of the 'one-bottle' system was light-cured before placing the resin cement and the post. Twenty translucent fiber posts were used. Then, root samples were processed for SEM observation.

RESULTS

The adhesive system showed resin dentin interdiffusion zone (RDIZ), resin tag and adhesive lateral branch formation. Microscopic examination of restored interfaces of Group 1 showed a higher % (P < 0.05) of RDIZ than those found in samples of Group 2. In Group 2 samples RDIZ morphology was well detectable and uniform in the first two thirds of root canals while in the apical third the RDIZ was not uniformly present while in Group 1 RDIZ was visible at the apical third too. No statistically significant differences were found among the two groups coronally and at the middle third, while the apical third of Group 1 showed significantly more resin tags than in Group 2. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of the root canals of both groups and at the apical third of Group 1. In the apical third of Group 2 root canals, the resin tags showed a less uniform morphology and a shorter length than those found in the other observed thirds.

Intracanal placement of calcium hydroxide: a comparison of two different mixtures and carriers

Objective. The purpose of this study was to compare the placement techniques of Ca(OH)(2). Study Design. Forty simulated curved canals (42 degrees) in transparent resin blocks were used and separated into 4 experimental groups, 10 canals each. A paste of Ca(OH)(2) was mixed with either water or glycerin and placed into canals with Lentulo spiral or Pastinject. Radiographs were taken of each sample. The canal fillings were evaluated by 3 endodontists and scored as to length of placement and completeness of fill. Cohen's kappa test was used to measure agreement between raters, and Kruskal-Wallis analysis of variance test was used to determine statistical differences between the 4 groups. Results. As to length of placement, statistically significant differences were found between Ca(OH)(2) + water pastes filled with Lentulo spiral (group 1) and Ca(OH)(2) + glycerin pastes filled with either Pastinject or Lentulo spiral. The findings of group 1 showed that the paste was short of the apex by more than 2 mm, whereas the other 3 groups were either at the apex or only 1 to 2 mm short. As to middle and coronal completeness of fill, differences were found to be statistically significant between Ca(OH)(2) + water paste filled with Lentulo spiral group and the other groups. Most of the canals in group 1 had greater than one-half void space at apical third, whereas the canals had less than one-fourth void space when Ca(OH)(2) + glycerin pastes were filled with Pastinject. Conclusions. Ca(OH)(2) when mixed with glycerin and placed into the canals, either with a Lentulo spiral or Pastinject, provided satisfactory results. Pastinject showed better fillings with Ca(OH)(2) + water pastes than Lentulo spiral.

Root canal filling with calcium hydroxide using different techniques

Several different techniques for placing calcium hydroxide into root canals have been proposed, such as amalgam carriers, vertical pluggers, McSpadden compactors, Lentulo drills, files and special syringes. Because correct filling of the root canal is necessary for calcium hydroxide paste to act effectively, the aim of this research was to study different techniques of root canal filling with calcium hydroxide pastes in dog teeth. The placement of calcium hydroxide with a file, absorbent paper points and vertical pluggers presented the lowest number of empty spaces in the three thirds of the root canal, followed by the Lentulo drill and the McSpadden compactor.

Evaluation of leakage of bacteria and endotoxins in teeth treated endodontically by two different techniques

Root canal recontamination occurs after contact between oral-bacterial flora and the coronal extremity of the root canal. The aim of this study was to evaluate the time required for endotoxins and bacteria to penetrate through root-canal obturations performed with vertical and lateral gutta-percha condensation techniques. Specimens prepared by the two alternative methods were exposed to contaminated saliva, and leakage into the root was evaluated over time. None of the obturated roots was infiltrated by endotoxins after 31 days. On the contrary, between day 13 and day 37 bacteria had infiltrated all specimens.

In vivo performance of the new non-instrumentation technology (NIT) for root canal obturation

AIM

The aim of this in vivo study was to compare the radiographic quality of root fillings performed by the NIT-obturation method versus conventional mechanical obturation.

METHODOLOGY

Sixty-six patients needing root canal treatment participated in this study. The treatments were performed by three private practitioners. The root canals were instrumented with K-Flexofiles to a master apical file between sizes 25 and 60, followed by step-back flaring up to size 70. Copious irrigation was used throughout the instrumentation procedure with NaOCl (3%). The teeth were obturated either by lateral condensation, the McSpadden technique (control) or by the new non-instrumentation technology (NIT) with and without using gutta-percha points. In the NIT method, a low pressure was created within the tooth, and AH 26 sealer was sucked into the root canal system. Radiographs of the root-filled teeth were analysed and the length of the root filling, the presence of voids and the area of any other fillings determined.

RESULTS

The root canal fillings of the control group (0.1 +/- 0.1 mm) and those of the NIT/gutta-percha group (0.3 +/- 0.1 mm) were both overextended when taking the apical constriction as a reference point. Root canal fillings of the NIT/gutta-percha group were statistically (P < 0.05) significantly longer than those of the NIT without gutta-percha group. The latter showed slightly underextended root canal fillings (-0.14 +/- 0.1 mm).

CONCLUSIONS

The present investigation demonstrated the performance of the NIT-obturation method in vivo. Root canals filled by the reduced-pressure-method using sealer combined with gutta-percha cones exhibited equivalent radiographic quality compared to conventionally filled canals.

Microbial leakage evaluation of the continuous wave of condensation

Coronal leakage has been recognized as a cause of pulpal and periradicular disease. Although cleaning and shaping of the root canal system is considered paramount, obturation of the system is an important step in endodontic success. The purpose of this study was to evaluate coronal bacterial leakage in teeth obturated with the System B continuous wave of condensation technique, followed by an Obtura II backfill, versus teeth obturated using the lateral condensation technique. Sixty single-rooted bilaterally matched teeth were evaluated in this study. An anaerobic bacterial leakage model was used. Results indicate that microbial coronal leakage occurs more quickly using lateral condensation than with the System B continuous wave of condensation and Obtura II backfill. This difference was statistically significant (p < or = 0.05). However, there was no statistical difference between groups 1 and 2 in the numbers of teeth that demonstrated bacterial leakage at the end of the study.

Effect of irrigating solution and calcium hydroxide root canal dressing on the repair of apical and periapical tissues of teeth with periapical lesion

The objective of this study was to evaluate the apical and periapical repair after endodontic treatment of teeth with pulp necrosis and a chronic periapical lesion in dogs. Seventy-two root canals from four mongrel dogs were submitted to biomechanical preparation, using 5.25% sodium hypochlorite or 2% chlorhexidine digluconate as the irrigating solution. The root canals were subsequently either filled immediately with Sealapex, using active lateral gutta-percha condensation, or a calcium hydroxide root canal dressing was applied for 15 days before filling with Sealapex. After 210 days, the animals were killed by anesthetic overdose, and the obtained histological sections were stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical repair. There was better histological repair in the groups with the root canal dressing (p < 0.05) than the groups with immediate obturation. Comparing the immediate obturation groups, irrigation with chlorhexidine solution resulted in better repair than sodium hypochlorite.