The use of ultrasonic endodontic instrumentation in the re-treatment of a paste-filled endodontic tooth

In Vitro Comparison of Efficacy of Neolix and ProTaper Universal Retreatment Rotary Systems in Removal of Gutta-Percha Combined with Two Different Sealers

Statement of the Problem

The complete removal of filling material is an important step to regain access to the entire canal and facilitate the disinfection of the root canal system. Rotary nickel-titanium (NiTi) instruments systems have been proposed as an effective removal technique for root canal retreatment.

Purpose

The aim of this study was to evaluate the efficacy of Neolix rotary system and ProTaper Universal retreatment system in the removal of gutta-percha combined with two different sealers.

Materials and Method

In vivo study, eighty extracted human permanent mandibular premolars were prepared using the ProTaper Universal rotary system to an apical size 30 (F3/0.06). The specimens were randomly divided into 4 groups (n=20) and subsequently filled with lateral condensation of gutta-percha and two sealers: AH-26 and Sure-Seal Root. The teeth were stored for 4 weeks at 37°C and 100% humidity and then retreated by one of the following rotary systems: Neolix or ProTaper Universal retreatment system. Teeth were then grooved and monitored under a stereomicroscope with 8× magnification. The images were transferred to the computer and the amount of filling material that remained on the root canal walls was scored using AutoCAD 2017 version 1.1software. Results were analyzed using one-way analysis of variance test and post hoc Tukey-HSD test (p< 0.05).

Results

The mean percentage of remaining gutta-percha and sealer was significantly higher in apical third in all groups (p< 0.01). Post hoc Tukey test showed that there is significantly higher residual filling material in the group filled with gutta-percha and Sure-Seal Root sealer and retreated by Neoniti rotary system compared with other groups in both coronal and middle third of the canal.

Conclusion

The Neoniti rotary system was as effective as ProTaper Universal retreatment system in retreatment of gutta-percha and AH-26 sealer but was significantly less effective in groups obturated with Sure-Seal Root sealer.

An in vitro CT Comparison of Gutta-Percha Removal with Two Rotary Systems and Hedstrom Files

INTRODUCTION

To evaluate the efficacy of NiTi mechanical rotary instrumentation and Hedstrom file for gutta-percha/sealer removal computed tomography (CT) was utilized in vitro.

MATERIALS AND METHODS

Thirty extracted human single rooted teeth, each with a single canal were selected. The samples were decoronated with a double faced diamond disk to have 17-mm root; teeth roots were instrumented with K-files up to master apical file #30 using step back technique. Samples were obturated using cold lateral condensation of gutta-percha and AH Plus root canal sealer. The teeth were then randomly divided into three groups of 10 specimens each. After 2 weeks 3-dimensional images of the roots were obtained by CT and the volume of root filling mass was measured. All the canals were then retreated by either the ProTaper retreatment files, Mtwo retreatment files or Hedstrom files. The canals were irrigated with 2 mL of 2.5% sodium hypochlorite irrigating solution during each change of instrument. The volume of remaining filling materials after the retreatment procedures was assessed by CT. Statistical analysis was performed with one-way ANOVA and Tukey's post hoc test.

RESULTS

Neither of studied systems completely removed the root filling material. No significant difference was observed between the rotary systems. The volume of remaining filling materials was significantly less in rotary instrumentation than hand files. There was no significant difference for debris extruded from the apical foramen between the groups.

CONCLUSION

Under the experimental conditions, Mtwo and ProTaper retreatment files left less gutta-percha and sealer than H files; however, complete removal of filling materials was not achieved by the three systems investigated.

Retreatability of a bioceramic root canal sealing material

INTRODUCTION

The efficacy of retreatment techniques for BC Sealer (BCS) (Brasseler USA, Savannah, GA) removal has not yet been assessed. The purpose of this study was to evaluate the efficacy of solvent and rotary instrumentation in the removal of BCS when used in combination with gutta-percha (GP) as compared with AH Plus sealer (Dentsply, Tulsa, OK).

METHODS

The mesiobuccal canals of 40 mandibular molars were instrumented and obturated with either GP/AH Plus with warm vertical compaction or GP/BCS using a single cone. The groups were subdivided into samples with the master GP cone placed to the working length (WL) or intentionally 2 mm short of the WL. Canals were then retreated using heat, chloroform, rotary instruments, and hand files. The ability to regain the WL and patency were evaluated as well as the time required to remove obturation material. Representative samples were also analyzed via scanning electron microscopy.

RESULTS

The WL was not regained in 70% of samples with BCS/master cone short of the WL. Patency was not re-established in 20% of samples with BCS/master cone to the WL or in 70% of samples with BCS/master cone short of the WL.

CONCLUSIONS

Conventional retreatment techniques are not able to fully remove BCS.

Efficacy of Two Rotary NiTi Instruments in the Removal of Gutta-Percha During Root Canal Retreatment

The aim of this study was to evaluate the efficacy of ProTaper and K3 in the removal of gutta-percha during root canal retreatment in comparison with hand Hedstrom files. Time of gutta-percha removal and amount of apically extruded debris were also evaluated. Sixty extracted single-rooted anterior teeth and premolars were instrumented and obturated with laterally condensed gutta-percha technique. The teeth were cleared and randomly divided into three groups of 20 teeth each. The roots were split longitudinally, digital images were created using a scanner, and the areas of remaining filling material were traced using Ulead Photoimpact7 then calculated using SigmaScan software. The results indicated that the two rotary nickel-titanium instruments left significantly less remaining filling material than hand instruments (p < 0.001). The ProTaper and K3 required significantly less time for filling material removal than hand instruments (p < 0.001). There was no statistically significant difference among the three techniques regarding the amount of apically extruded debris (p = 0.159). In conclusion, ProTaper and K3 were found to be effective and faster in removing gutta-percha.

Dissolving efficacy of organic solvents on root canal sealers

The aim of this study was to evaluate the solubility of three types of root canal sealers in three organic solvents used in endodontics. The solubility of calcium-hydroxide-based (Sealer 26), silicon-polydimethylsiloxane-based (RoekoSeal), and zinc-oxide-eugenol based (Endofill and Intrafill) sealers was assessed in eucalyptol, xylol, orange oil, and distilled water. Eighty samples of each filling material were prepared according to the manufacturers' instructions and then divided into four groups for immersion in solvent for 2 or 10 min. The means of sealer dissolution in solvents were obtained by the difference between the original preimmersion weight and the postimmersion weight in a digital analytical scale. Data were statistically analyzed with the Student's t test, and multiple comparisons were performed with Student-Newman-Keuls. Xylol and orange oil showed similar effects, with significant solubilization (P<0.05) of the tested cements. Endofill and Sealer 26 did not show any significant difference in solubilization at the two immersion times, whereas RoekoSeal and Intrafill showed a more pronounced solubility at 10 min. The lowest levels of solubilization occurred in RoekoSeal, Sealer 26, Endofill, and Intrafill. It is concluded that xylol and orange oil presented similar solvent effects with a significant solubility of the tested cements.

Comparison of the Cutting Efficiency of Two Ultrasonic Units Utilizing Two Different Tips at Two Different Power Settings

The objective of this in vitro study was to set up a testing protocol and utilize it to evaluate and compare the cutting efficiency of ultrasonic units. Evaluation of two ultrasonic units utilizing two different tips was done by measuring the weght of a dentin specimen before and after ultrasonic treatment for set time periods. The difference in weight was the amount of dentin removed. The ultrasonic units tested were the P5 Booster (Staelec, France) and the Spartan (Obtura-Spartan, Fenton, MO) machines. The tips tested were the CPR-2D and ETD20 types. The units were tested at maximum and medium power. All the experimental variables, ultrasonic unit type, power setting and tip type were found to have an effect on the cutting efficiency (P<0.0001). The P5 ultrasonic unit was more effective at dentin removal than the Spantan ultrasonic unit at both power settings. The ETD-20 tip was more effective at dentin removal than the CPR-2D tip on both units at both power settings.

Removal of Two Types of Root Canal Filling Material Using Pulsed Nd:YAG Laser Irradiation

OBJECTIVE

The aim of this study was to examine the usefulness of a pulsed Nd:YAG laser in removing two types of endodontic obturation material from the root canal in vitro.

BACKGROUND DATA

Recently, a fine flexible glass fiber made of quartz has been developed to transmit the laser beam more effectively and permit its concentration in a specific area. This has increased the potential usefulness of the Nd:YAG laser in root canal treatment.

METHODS

The time required for removing the root canal obturation material (Gutta-percha cones and, Sealapex or AH26) by means of either Nd:YAG laser irradiation or a conventional method (Gates Glidden drills and K files) was measured. Contact microradiography was used to assess the radiopacity of the root canals before and after the removal of obturation material. The surfaces of the root canal after removal of the obturation materials were also observed by scanning electron microscopy.

RESULTS

Although none of the methods used in this study resulted in complete removal of debris from the root canal wall, the time required for the removal of any of the root canal obturation materials using laser ablation was significantly shorter than that required using the conventional method (p < 0.05). It appeared that some orifices of the dentinal tubules were blocked with melted dentin following laser irradiation.

CONCLUSIONS

Nd:YAG laser irradiation is an effective tool for the removal of root canal obturation materials, and may offer advantages over the conventional method.

Gutta-percha retreatment: effectiveness of nickel-titanium rotary instruments versus stainless steel hand files

This study compared the cleanliness of the root canal walls after retreatment using nickel titanium (NiTi) rotary and stainless steel (SS) files. Also compared were time of retreatment and canal deviation. Forty extracted canines were step-back prepared and obturated with gutta-percha and sealer. Retreatment was performed either by using chloroform and SS hand files or chloroform and NiTi rotary files. Time for retreatment was recorded. Radiographs of the root canal system before and after retreatment were made. Teeth were split longitudinally, photographed, and projected onto a screen. The amount of gutta-percha/sealer remaining on the canal walls was then traced and measured. The amount remaining was analyzed and compared statistically between NiTi and SS groups by t test. Results showed that the mean percentage of wall coverage by remaining obturating material in the SS group was 13.6% and was 15.2% for the NiTi group. There was no statistically significant difference (p = 0.361). No severe canal deviation occurred with either retreatment method. Mean retreatment time for the SS group was 6.3 min and 7.9 min for the NiTi group; the difference was statistically significant (t test p < 0.001). In conclusion, NiTi rotary and SS hand were similar in material remaining after retreatment, but SS hand was a bit faster.

Evaluation for cracks associated with ultrasonic root-end preparation of gutta-percha filled canals

Many clinicians use ultrasonics for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched human teeth for cracks before and after ultrasonic root-end preparation. Twenty matched pairs of extracted single rooted teeth were divided into two experimental groups. In group 1, root-end resection was performed on uninstrumented teeth. In group 2, root-end resection was performed after the canals were instrumented and filled with gutta-percha. All teeth in both groups received root-end preparations using ultrasonic instrumentation at low power. Two examiners evaluated the root-ends after root-end resection and again after root-end preparation using zoom magnification of 20x to 63x. The number, types, and location of cracks were mapped. There were no significant differences when gutta-percha filled roots were compared to uninstrumented roots with regard to the number or type of cracks after root-end resection or root-end preparation. In addition, there were no significant differences in the number or type of cracks following root resection and ultrasonic root-end preparation when compared to teeth with root resection alone.

Retreatment using a modified-tip instrument

The purpose of this article is to present a technique in which a modified file is used with reaming motion and apical pressure in retreatment cases.

Residue of gutta-percha and a glass ionomer cement sealer following root canal retreatment

A previous report indicates that root canals obturated with a new glass ionomer cement endodontic sealer (Ketac-Endo, Espe, Germany) and laterally condensed gutta-percha can be retreated by ultrasonic instrumentation. To address the possibility of Ketac-Endo being used without condensation of gutta-percha, the purpose of this study was to evaluate the efficacy of ultrasonic retreatment in canals obturated with single-cone gutta-percha and Ketac-Endo. Thirty root canals were prepared in a standardized way to ISO size 40 and obturated with gutta-percha and Ketac-Endo. Either a size 40 gutta-percha cone was used with and without lateral condensation, or a size 25 single cone, without condensation. After 14 days, the canals were retreated using chloroform and ultrasonic instrumentation. The roots were split vertically, and the amount of residual debris on the canal walls was assessed by three examiners using a dissecting microscope. Debris was recorded in the apical, middle and coronal canal levels according to a preset evaluation scale. The mean scores for each group were compared by ANOVA and Mann-Whitney U-test, with a 5% level of significance. In the roots obturated with lateral condensation the amounts of residual debris in the coronal and middle canal levels was lower than in the other two groups, whereas in the apical level it was higher. Statistically, only the differences in the apical level were significant (P < 0.03). It was concluded that ultrasonic retreatment may be performed effectively in root canals obturated with single-cone gutta-percha and Ketac-Endo.

Endodontic retreatment: a rational approach to root canal reinstrumentation

During nonsurgical endodontic retreatment, endodontic instruments are forced apically to remove the root canal filling material and regain canal patency. Undiscriminating burrowing down the canal in the apical direction may be fruitless and harmful. To avoid complications, the dentin overhanging the canal orifice must be removed and an unobstructed access established to the root filling material, so as to facilitate its removal. Reinstrumentation of the filled canal must take into consideration the nature of the filling material and the physical properties of endodontic instruments, as well as the dynamic aspects of canal preparation. This article discusses the mechanical considerations pertaining to root canal retreatment and outlines a step by step rationale approach to retreatment.

Efficient amalgam core elimination and root preservation with ultrasonic instrumentation

An efficient ultrasonic vibratory energy technique for the elimination of deeply placed amalgam core in an endodontically treated tooth is presented. Root integrity is ensured by avoiding complete reliance on rotary burs for the removal of the obstructing alloy.

Efficacy of removing glass ionomer cement, zinc oxide eugenol, and epoxy resin sealers from retreated root canals

Removal of gutta-percha and various sealers was assessed during retreatment of the root canal system. Sixty root canals were prepared and obturated with gutta-percha and Ketac-endo, Roth's 801 cement, or AH26. After 14 days, the canals were retreated by hand or ultrasonic technique and the retreatment time was recorded. The roots were split and the amount of debris that remained on the canal walls in three separate levels was recorded by use of a dissecting microscope. The mean scores were compared by one-way and two-way ANOVA. The total score was significantly the highest for Ketac-endo (p less than 0.04), followed by AH26 and Roth's 801 cement. The largest amount of debris was consistently found in the apical third, and generally it was comparable for both retreatment techniques. The ultrasonic technique was significantly faster than the hand technique for all sealers tested (p less than 0.0004, p less than 0.0003, p less than 0.02, respectively). Hand retreatment of Ketac-endo was the slowest, whereas ultrasonic retreatment of Roth's 801 cement was the fastest. The results indicated that Ketac-endo endodontic sealer can be effectively removed from the root canal by ultrasonic instrumentation.

Effectiveness of halothane used with ultrasonic or hand instrumentation to remove gutta-percha from the root canal

This study compared halothane and chloroform used with hand or ultrasonic instrumentation to remove gutta-percha and sealer from root canals. Apically extruded debris, residual debris, time for filling removal, and amount of solvent used were determined. The differences in extruded apical debris and radiographically visible residual debris were not significant (p greater than 0.05). Ultrasonic instrumentation required significantly less time to remove the root canal filling than did hand instrumentation (p = 0.02). The only significant difference in the amount of solvent used occurred when the ultrasonic-chloroform group was compared with the hand instrumentation-chloroform group (p = 0.05). Halothane was found to be an acceptable alternative to chloroform for removing gutta-percha and sealer from the obturated root canal.

Endodontic retreatment--case selection and technique. 3. Retreatment techniques

The necessity to remove filling materials from the root canals is one of the major differences between primary endodontic therapy and retreatment. The obturating material has to be removed from the root canals before routine endodontic therapy can be performed. The removal of the material should not result in a change in the canal morphology, so that the objectives of endodontic therapy can be maintained. Numerous techniques may be used for removing filling materials and other obstructions from root canals. This article reviews the techniques that were suggested in the literature for this purpose and discusses their advantages and disadvantages.