Effect of mechanical versus thermal removal of gutta-percha on the quality of the apical seal following post space preparation

Radiographic Evaluation of the Gap between Cemented Post and Remaining Gutta-Percha in Endodontically Treated Teeth Performed by Undergraduate Students: A Retrospective Cross-Sectional Study

The coronal seal in root canal-treated teeth may be compromised depending on the accuracy of post space preparation and post cementation along with remaining gutta-percha. Root canal treatment can be compromised by endotoxins released by the coronal bacteria as a result of microleakage. The study was conducted by undergraduate students to measure the gap between the cemented post and residual gutta-percha. In total, 217 endodontically treated teeth were evaluated with intraoral peri-apical radiographs. Based on the intraoral periapical radiographic examination in the CS-R4 program, Group I had no gap, Group II had a gap of >0 to 2 mm, and Group III had a gap of more than 2 mm between the end of the cemented post and the remaining gutta-percha. In total, 40% (n = 87) of the teeth had no gap, 59% (127) had a gap of >0 to 2 mm, and 1% (n = 3) had a gap of more than 2 mm between the cemented post end and remaining gutta. Chi square test revealed a significant difference in the gap between the post and remaining gutta-percha between males and females students (p < 0.001). In terms of the gap between the cemented post end and the residual gutta-percha, the root canal treated teeth with post and core by undergraduates were clinically acceptable.

Comparative evaluation of apical microleakage in immediate and delayed postspace preparation using four different root canal sealers: An in vitro study

BACKGROUND

Endodontically treated teeth often lack sufficient support for a permanent restoration. During post space preparation, it is important not to disturb the integrity of the apical seal.

AIM

This study compared the effect of immediate versus delayed post space preparation on the apical seal using four different sealers.

MATERIALS AND METHODS

One hundred and thirty single rooted teeth were biomechanically prepared and obturated with single cone gutta-percha and 4 sealers: Endoflas FS, AH Plus, Gutta flow and MTA. Teeth were divided randomly into eight groups, post spaces were prepared using Gates Glidden drills immediately for group I, III, IV and VII. For groups II, IV, VI and VIII prepared after storage of the specimens in 100% humidity for one week. The samples were kept in methylene blue dye, centrifuged at 3000 rpm for 3 min sectioned and then measured under stereomicroscope for apical leakage.

STATISTICAL ANALYSIS

The data was analysed using one way ANOVA and post hoc Tukey test.

RESULTS

All the specimens showed dye leakage, and a statistically significant difference was seen among all the groups (P > 0.05) except Gutta flow.

CONCLUSION

Less leakage is seen when post space is prepared immediately.

Effectiveness of Sonic, Ultrasonic, and Photon-Induced Photoacoustic Streaming Activation of NaOCl on Filling Material Removal Following Retreatment in Oval Canal Anatomy

OBJECTIVE

This study aimed to assess the effectiveness of sonic, ultrasonic and laser [photon-induced photoacoustic streaming (PIPS)] irrigation activation in removing filling remnants from oval root canals after standard canal retreatment procedures with the ProTaper universal rotary retreatment system.

METHODS

Twenty-eight maxillary first premolars were instrumented with ProTaper NiTi rotary instruments and obturated with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. After storage at 37°C and 100% humidity for 1 week, the specimens were retreated with the ProTaper universal retreatment system for the removal of filling material. Teeth were then randomly assigned into four groups (n = 7): group 1, positive control; group 2, retreated with sonic irrigation; group 3, retreated with ultrasonic irrigation; and group 4, retreated with laser irradiation. The specimens were scanned using micro-CT before instrumentation, after obturation and mechanical retreatment, and after additional activation procedures. The percentage volume of the filling remnants was measured. Specimens were split longitudinally after micro-CT scan, canal walls were examined using scanning electron microscopy (SEM), and the amount of residual filling material was scored.

RESULTS

The filling materials' removal efficacy in the three experimental groups was higher than that of the control group (p < 0.05), whereas filling materials ranging from 1.46 ± 0.30 to 2.21 ± 0.46 mm(3) remained in the canal in all three experimental groups. Additionally, there was a significantly greater reduction in the amount of filling remnants in the PIPS group than in the sonic and ultrasonic groups (both p < 0.05), and significantly greater reduction in the ultrasonic group than the sonic group (p < 0.05).

CONCLUSIONS

Activation of NaOCl with PIPS showed significantly better performance than sonic and ultrasonic techniques in removing the filling remnants following mechanical retreatment of oval root canals. The ultrasonic technique also performed better than the sonic technique. However, none of the additional activation procedures was able to completely eliminate the filling remnants.

Effect of immediate and delayed post space preparation on apical leakage using three root canal obturation techniques after rotary instrumentation

BACKGROUND/PURPOSE

For teeth that have undergone root canal therapy post fabrication and subsequent crown restoration are often required to increase strength. It is necessary to remove a portion of gutta-percha during post space preparation that may cause displacement of the root canal fillings and affect their sealing ability. This study evaluated the effects of different post space preparation time intervals and root canal obturation techniques on the apical sealing ability of filled root canals.

METHODS

One hundred single-canal teeth were incrementally crown-down enlarged to an apical diameter of 0.40 mm with 0.06 taper by K3 rotary instrumentation, combined with 5.25% NaOCl irrigation. The teeth were randomized into four groups: 30 obturated by lateral compaction technique (Group 1); 30 by vertical compaction technique (Group 2); 30 by injectable thermoplasticized gutta-percha technique (Group 3); and 10 controls with no obturation (Group 4). All specimens were stored in 100% humidity at 37°C. Immediately and 3 days and 7 days after obturation, post space was made utilizing heated pluggers, and leaving a 5.0-mm gutta-percha filling. The teeth were immersed in 2.0% methylene blue solution for 72 hours, and finally cut longitudinally in half. Dye leakage was examined under a stereomicroscope. The results were recorded and statistically analyzed.

RESULTS

The mean distance of dye leakage after post space preparation at three different time intervals in Group 1 were greater than those in Groups 2 and 3. One-way analysis of variance indicated that the apical seal or adaptation of vertical compaction technique and injectable thermoplasticized gutta-percha technique were not easy to break during post space preparation.

CONCLUSION

Teeth treated by vertical compaction and injectable thermoplasticized gutta-percha techniques showed less leakage than those treated by lateral compaction. The least amount of dye leakage existed when the post space preparation was made on day 7 after root canal obturation.

Comparison of GPX with or without solvent and hand files in removing filling materials from root canals--an ex vivo study

OBJECTIVE

The aim of this study was to compare GPX instruments and hand files for gutta-percha removal.

STUDY DESIGN

Fifty maxillary central incisors with a single straight canal were instrumented and filled. The teeth were divided into 5 groups of 10 specimens each, according to the gutta-percha removal techniques: group 1: GPX (21-mm-long teeth); group 2: GPX and xylol as solvent (21-mm-long teeth); group 3: GPX (25-mm-long teeth); group 4: GPX and xylol as solvent (25-mm-long teeth); and group 5: hand files and xylol as solvent. The amount of time for gutta-percha removal and the number of fractured instruments were evaluated. Radiographs were taken, and the teeth were grooved longitudinally and split. The area of residual debris was measured using Sigma Scan software.

RESULTS

The time for filling material removal was significantly shorter when GPX was used (P < .05). Overall, hand files and solvent produced fewer remnants of filling materials (P < .05). In the GPX 25 mm-long teeth group, the filling material was not removed in the apical third.

CONCLUSIONS

Under the experimental conditions, the GPX instruments proved to be faster than hand instruments in removing root filling materials; however, hand instruments left a smaller amount of residual filling materials on the canal walls. The GPX instruments did not pull the gutta-percha beyond its tip.

Effect of immediate and delayed post space preparation on the apical seal of root canals obturated with different sealers and techniques

During mechanical preparation of the post space, the root canal filling may be twisted or vibrated, depending on several factors associated with the preparation technique and quality of filling.

Comparative in vivo analysis of the sealing ability of three endodontic sealers in dog teeth after post-space preparation

This study compared the sealing ability of RoekoSeal, AH Plus and EndoRez in dog premolars after post-space preparation and exposure to the oral environment. Seventy-four root canals were cleaned, shaped and filled with gutta-percha and one of the sealers. Post spaces were prepared with about 4-mm root canal filling remaining in the apex. Teeth were sealed for 24 h for sealer setting. Teeth were exposed to the oral environment for 45 days. The dogs were killed and root canals were soaked in India ink and sealed for 96 h. The teeth were cleared, and leakage was measured under stereoscopy. The Kruskal-Wallis test was used for analysis. A significant difference was found between EndoRez and RoekoSeal groups (P < 0.05). EndoRez had lower leakage values than RoekoSeal after 45-day exposure to the oral environment. No statistic difference was found in the comparison of AH Plus with the other sealers under study.

The Effect of the Distance Between Post and Residual Gutta-Percha on the Clinical Outcome of Endodontic Treatment

To determine whether the distance between the post and the residual gutta-percha influences the clinical outcome of endodontic treatment, 94 endodontically treated teeth following post and core restoration were evaluated radiographically. The teeth were divided into three groups: (I) no gap between the gutta-percha and the post; (II) a gap of >0 to 2 mm; (III) a gap of >2 mm. Treatment outcome was evaluated in follow-up radiographs, taken 1 yr after treatment and up to 5 yr posttreatment. In group I, 83.3% of the teeth were evaluated normal, 53.6% of group II, and only 29.4% of group III. A gap between the gutta-percha and the post was related to an increased rate of emerged disease in endodontically treated teeth restored with a post and core.

Calcium hydroxide as a temporary filling of the post space in root-filled teeth

OBJECTIVE

The purpose of this in vitro study was to evaluate whether the saline content of the calcium hydroxide paste used as a temporary filling in the post space of root-filled teeth would significantly affect the seal of the apical root fillings (gutta-percha and zinc oxide-eugenol based sealer) during a period of 1 month.

STUDY DESIGN

Eighty extracted single-rooted and multirooted teeth were cut at the cemento-enamel junction. They were endodontically instrumented and filled with zinc oxide-eugenol based sealer and gutta-percha. A post space was immediately prepared on 70 teeth. The experimental teeth were then randomly divided into 4 groups: A, post space filled with calcium hydroxide paste (30 teeth); B, post space without calcium hydroxide paste (30 teeth); C, negative controls (10 teeth); and D, positive controls (10 teeth). The teeth were stored in a humidified chamber at room temperature for a month. After storage, the calcium hydroxide paste in the post spaces in group A was removed. All roots were coated with 2 layers of nail varnish and sticky wax externally, placed in a glass bottle containing methylene blue, and subjected to a vacuum for 15 minutes. The teeth were then stored for another week, sectioned in half longitudinally, and examined for dye penetration. The mean and standard deviation of dye penetrations for each group were calculated, and a Student t test was used to determine the statistical difference between the groups.

RESULTS

There was no significant difference in the coronal dye leakage of the apical root fillings between the post spaces filled with the calcium hydroxide paste and those without during a period of 1 month.

CONCLUSIONS

The saline content in the calcium hydroxide paste placed in the post space as a temporary filling did not significantly affect the seal of the apical root fillings during a period of 1 month by using a dye leakage study.

Post retention: the effect of sequence of post-space preparation, cementation time, and different sealers

Many endodontic sealers contain constituents that have been shown to inhibit the polymerization of resin cements. This may be important when prefabricated posts are cemented at the same appointment as root canal obturation. This study evaluated the effects of cementing posts with a resin cement immediately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space preparation was also assessed as a critical variable. One hundred twenty extracted canines were randomly divided into eight experimental groups. The variables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. All teeth received a stainless steel #6 Parapost XP cemented with a resin cement, Panavia 21. Each experimental group underwent tensile testing for retention using an Instron universal testing machine. For both sealers posts cemented in teeth in which the canal was obturated before post-space preparation and thus had sealer-contaminated dentin removed by the space preparation procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sealer used and time of cementation had no specific effect on retention. Achieving a clean, "freshened" dentinal surface during mechanical post-space preparation seems to be a critical variable for post retention when a resin cement is used.

The effect of immediate vs. delayed post space preparation on the apical seal of a root canal filling: a study in an increased-sensitivity pressure-driven system

A 5 mm remaining length of root canal filling, after post space preparation, is commonly assumed to maintain sealing ability similar to that of the intact filling. Post spaces were prepared either immediately using hot pluggers, or later, using drills. The sealing ability of the fillings, 5 mm remaining length, were compared with each other and with an intact root canal filling control, using radioactive tracer in a pressure-driven system. When no pressure was applied, no differences could be detected between either of the groups and the control. When a pressure of 120 mm Hg was applied to the same teeth, the control group clearly maintained a better seal than each of the experimental groups, which did not significantly differ from each other. These results suggest that (a) the pressure-driven system was more sensitive than the passive leakage assay that failed to detect differences even at 14 days; (b) a remaining root canal filling of 5 mm was inferior to the intact root canal filling; and (c) the immediate post space preparation with hot pluggers did not differ from a delayed preparation with drills.

Effect of immediate and delayed post preparation on apical dye leakage using two different sealers

Eighty freshly extracted teeth were endodontically prepared and filled with gutta-percha and either a zinc oxide-eugenol-based sealer or AH26 to determine what effect these sealers, with widely differing properties, would have on apical microleakage after either immediate or delayed dowel space preparation. The teeth were randomly assigned to 1 of 4 groups, and the post space was made either immediately after filling or after being stored in 100% humidity for 1 wk. They were then immersed in a 2% methylene blue solution under vacuum, washed, and split longitudinally. The extent of dye penetration was read by five independent observers and the results analyzed. The only significant difference was in the delayed preparation group with zinc oxide-eugenol sealer, which showed greater leakage than the other groups.

Root surface temperatures produced during post space preparation

In vitro root surface temperatures produced during post space preparation were measured. The preparations were made using a GPX bur with rotational speeds of 6,500, 8,000, 9,500, 11,000, and 15,000 rpm. The overall mean temperature increase ranged from 0.66 degree to 4.81 degrees C and was greatest at 8,000 rpm. When speeds > 8,000 rpm were used, temperature increases also resulted, but they were significantly less than that which occurred at 8,000 rpm. Damage to the supporting structures of teeth should not occur when this bur is used, at any of the speeds evaluated, to create a post space.

Apical sealing ability of Thermafil following immediate and delayed post space preparations

Sixty extracted human teeth were prepared in a step-back flare method. Forty-five were obturated with plastic Thermafil and 15 were filled with lateral condensation. The Thermafil filled teeth were divided into three groups consisting of no post preparation, immediate post preparation, or delayed post preparation. Post preparations were not performed (controls) on the laterally condensed specimens. After 10 days of exposure to methylene blue dye, the specimens were decalcified in nitric acid for 72 h. A volumetric analysis measuring absorbance was then performed on each specimen. Within the testing parameters, no significant differences in leakage were observed among the tested groups.

Effect of post preparation on the apical seal of teeth obturated with plastic thermafil obturators

The effect of post canal preparation on the apical seal of endodontically obturated teeth with plastic Thermafil obturators was studied in vitro. Fifty-four extracted human maxillary anterior teeth were divided into four experimental and two control groups. Two groups were obturated with lateral condensation or plastic Thermafil obturator techniques; this was followed by post space preparation. Two groups were obturated as described above except that post space was not prepared. Apical leakage was determined with the use of 2% methylene blue dye solution at an absolute pressure of 75 mm Hg. There were no statistically significant differences between any of the groups. The clinical implication of these findings is discussed.