The effect of smear layer on microbial coronal leakage of gutta-percha root fillings

The aim of this in vitro study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction. One hundred and twenty extracted human teeth with straight, single root canals were decoronated. The canals were prepared using the modified double-flared technique with balanced force under copious irrigation. The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 15 file. The teeth were divided randomly into experimental groups (80 teeth) and control groups (40 teeth). The root canals of 40 experimental and 20 control teeth were rinsed with 40% citric acid and 2% NaOCl to remove the smear layer before obturation. In experimental groups, 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with lateral condensation of cold gutta-percha and Apexit sealer. A further 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with the Trifecta technique with the same sealer. In control groups, 10 teeth with smear layer intact and 10 teeth with smear layer removed were obturated with lateral condensation of cold gutta-percha and Apexit sealer. These teeth were completely sealed both coronally and apically to serve as negative controls. The remaining 20 teeth with either smear layer intact or smear layer removed were not obturated and served as the positive controls. The root surface of each tooth was sealed with nail varnish. The cut end of a polypropylene tube was sealed around the coronal part of each root canal so that bacteria placed therein could move only through the obturated canal space. Each root was placed in a glass bottle containing sterile Todd-Hewitt Broth (THB) and aliquots of 0.5 ml of THB were injected into the polypropylene tube. The model system was centrifuged at 168 g. An innoculum of Streptococcus sanguis in THB was placed in each coronal chamber at 5-day intervals and daily observations were made for bacterial growth in the apical reservoir for 90 days. All positive control teeth showed bacterial penetration within 24 h, while the negative control teeth remained uncon-taminated throughout the test period. Leakage through the experimental teeth was variable ranging from 7 to 86 days. There was no statistical significant difference (P > 0.05) in leakage between the obturated canal when the smear layer was either removed or intact.     

Comparison of cold lateral condensation and a warm multiphase gutta-percha technique for obturating curved root canals

AIM: The aim of this project was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or multiphase gutta-percha obturation (Alphaseal). METHODOLOGY: A total of 108 freshly extracted human, mature single-rooted teeth were divided into two identical groups of 54 teeth on the basis of root canal shape. The canals were prepared to a minimum 0.055 taper and enlarged to size 35 at the apex. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one group were obturated using cold lateral condensation of gutta-percha and the canals of the other group were filled using a warm multiphase gutta-percha obturation technique. The extrusion of sealer and/or gutta-percha through the apex of the teeth was recorded using a simple yes/no scheme. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a four-point scale. RESULTS: Root canals filled by multiphase obturation had significantly more extrusion of sealer (P < 0.001) and gutta-percha (P < 0.001) than canals filled by lateral condensation. Canals filled by multiphase gutta-percha obturation had significantly less apical dye leakage than those obturated by lateral condensation (P < 0.05). Lateral condensation achieved significantly better scores for radiographic quality than multiphase obturation from the bucco-lingual view (P < 0.01). CONCLUSIONS: Under laboratory conditions multiphase gutta-percha had better sealability but poorer radiographic quality than lateral condensation.     

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.

Objective:

The purpose of this study was to investigate the effect of immediate and delayed post space preparation on the integrity of the apical seal.

Material and Methods:

Sixty-four extracted human incisors were biomechanically prepared using the step-back technique. Sixty roots were randomly assigned to 6 experimental groups of 10 teeth each and the remaining 4 roots served as positive and negative controls (n=2). The root canals in the different groups were obturated with cold lateral and warm vertical condensation of gutta-percha and one of two sealers (Sealapex and Diaket). Post space was prepared either individually or simultaneously. An insulated copper wire was cut into 10-cm-long pieces. In each canal, one piece was inserted to maintain contact with gutta-percha and extended to the outside as one of two working electrodes. A stainless steel wire with the same dimensions of those of the copper wire, used as the other working electrode, was immersed into the background electrolyte from the center of the bottle. The electrical current between standard and experimental electrodes in canals was measured over a period of 10 days applying a conductivity meter. The Kruskal-Wallis test (p=0.05) determined whether there was a significant difference in microleakage among the groups and the Mann-Whitney U test (p=0.01) was used for multiple comparison grouping variables.

Results:

The results suggest that only the differences between the root canal filling techniques were statistically significant (p<0.01). There were no statistically significant difference in the sealers and the times of filling removal for post space preparation (p>0.01).

Conclusion:

The quality of the root canal filling is important for the integrity of the apical seal.     

Evaluation of the Trifecta obturating technique

The aim of this project was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or the Trifecta obturating system. One hundred freshly extracted human mature, single-rooted teeth were divided into four identical groups of 25 teeth on the basis of root canal shape. The root canals of two groups were prepared in such a way as to produce a relatively parallel canal shape with little or no flare towards the coronal orifice. The root canals of the other two groups were prepared in such a way as to produce a canal shape that was deliberately more flared to ensure that they were wider at the orifice than at the endpoint of the preparation. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one flared and one parallel group were obturated using cold lateral condensation and the canals of the other two groups were obturated using the Trifecta system. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a 4-point scale. Canals filled with thermoplasticised gutta-percha had significantly less apical dye penetration than those obturated by lateral condensation (P < 0.001). Lateral condensation achieved significantly better scores for radiographic quality than thermoplasticised gutta-percha from both the bucco-lingual (P < 0.001) and the mesio-distal views (P < 0.001). Root canals obturated using the Trifecta technique showed significantly more apical extrusion of sealer than those obturated by lateral condensation (P < 0.001). Under laboratory conditions the Trifecta technique had better sealability but poorer radiographic quality than lateral condensation.     

Quality of Obturation Achieved by a Non–gutta-percha–based Root Filling System in Single-rooted Canals

Introduction

The present study examined the quality of obturation in root canals filled by an experimental non–gutta-percha–based (NGP) root filling system using warm vertical or cold lateral compaction. The quality of obturation was evaluated by comparing the volumetric percentage of gaps and voids identified from similar canals obturated with gutta-percha and an epoxy resin–based sealer using the same obturation techniques.

Methods

Forty single-rooted premolars with oval-shaped canals were cleaned, shaped, and obturated with 1 of the 4 material/obturation technique combinations (n = 10). Filled canals were scanned with micro–computed tomographic imaging. Reconstructed images were analyzed for the volumetric percentage of gaps and voids at 3 canal levels (0–4, 4–8, and 8–12 mm from the working length). Roots were sectioned at the 4-mm, 8-mm, and 12-mm levels. Scanning electron microscopic images of negative replicas of root sections were examined to quantify the circumferential percentage of interfacial gaps and the area percentage of intracanal voids. Data were analyzed with parametric or nonparametric statistical methods.

Results

A statistically significant difference was found for the volumetric percentage distribution of gaps and voids for “obturation technique” but not for “material.” Significantly higher percentages of gaps and voids were identified in canals obturated with the NGP system using cold lateral compaction. Examination of negative replicas ascribed this difference to a higher area percentage of interfacial gaps rather than more intracanal voids.

Conclusions

Using warm vertical compaction, the NGP system fulfils the objective of 3-dimensional obturation of the canal space in a manner comparable with the results achieved with gutta-percha and a root canal sealer.     

A Comparative in Vitro Study of Apical Microleakage with Five Obturation Techniques: Lateral Condensation,Soft-Core?, Obtura II?, Guttaflow? and Resilon?

Aim

A comparison was made between the root canal lateral condensation technique and other condensation techniques in which physical (temperature: Soft-Core®, Obtura II®) or chemical changes (condensation: Guttaflow®, Resilon®) may affect the dimensional stability of obturation and thus favor apical microleakage.

Materials and methods

A total of 212 single-root teeth removed for orthodontic or periodontal reasons were randomized to 5 groups of 40 teeth each. Six samples were used as positive controls, and another 6 as negative controls. The teeth were worked with the Hero 642 system, and each group was obturated using a different technique: lateral condensation, Obtura II®, Soft-Core®, Guttaflow® or Resilon®. The samples were immersed in black ink, and after 72 hours the teeth were transparentized using the technique described by Robertson. Filtration of the ink was measured under the stereoscopic microscope. Analysis of variance and post-hoc testing were used for the statistical analysis.

Results

The Soft-Core® obturated group showed significantly greater microleakage than the other groups, with no differences among the rest of the groups.

Conclusions

Under the conditions of this study, the teeth obturated with the Soft-Core® technique showed greater apical microleakage than the other systems.Key words: Apical microleakage, root canal obturation, sealing ability, transparentization     

Comparison of laterally condensed and low-temperature thermoplasticized gutta-percha root fillings

The aim of this study was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or low-temperature thermoplasticized gutta-percha (Ultrafil). One hundred freshly extracted human, mature single-rooted teeth were divided into four identical groups of 25 teeth on the basis of root canal shape. The root canals of two groups were prepared in such a way to produce a relatively parallel shape with little or no flare toward the coronal orifice. The root canals of the other two groups were prepared in such a way as to produce a canal shape that was deliberately more flared to ensure that they were wider at the orifice than at the end point of the preparation. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one flared group and one parallel group were obturated using cold lateral condensation, and the canals of the other two groups were obturated using low-temperature thermoplasticized gutta-percha. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a 4-point scale. Canals filled with thermoplasticized gutta-percha had significantly less apical dye penetration than those obturated by lateral condensation (p < 0.001). Lateral condensation achieved significantly better scores for radiographic quality than thermoplasticized gutta-percha from both the buccolingual (p < 0.005) and mesiodistal views (p < 0.001). Low-temperature thermoplasticized gutta-percha root fillings were associated with significantly more apical extrusion of sealer (p < 0.001) and gutta-percha (p < 0.005). Under laboratory conditions the low-temperature thermoplasticized gutta-percha had better sealability but poorer radiographic quality than lateral condensation.     

Retention of fiber posts to the optimally and over-prepared dowel spaces

PURPOSE

To assess the retention of glass fiber post cemented with self-adhesive resin cement into optimum and over-prepared root canals following obturation in the presence of either eugenol (EB) or calcium hydroxide (CB)-based sealers.

MATERIALS AND METHODS

Roots of extracted premolars were endodontically-treated in 5 groups (n = 10). Roots of Group 1 (control) were left with no obturation and then optimally prepared to receive endodontic dowels. Other root canals were obturated with gutta-percha in the presence of either eugenol-based (Groups 2 and 4) or calcium hydroxide-based (Groups 3 and 5) sealer. Dowel spaces were prepared with optimal diameter in Groups 2 and 3, one size larger in Groups 4 and 5. Standardized fiber posts were luted to the prepared spaces using self-adhesive resin cement and itsretention was then tested on an universal testing machine. Both one-way ANOVA and Tukey''s HSD comparisons (α=0.05) were used to identifythe significance of inter-group retention differences. Scanning electron microscopy (SEM) of both optimally and over-prepared dowel spaces was also considered to figure the nature of their interior out.

RESULTS

The post retention was significantly higher to the non-obturated, optimally-prepared dowel spaces of Group 1 compared to the obturated, optimally-prepared ones of Groups 2 and 3. For each dowel space diameter, root canals obturated using CB of Groups 3 and 5 showed significantly higher dowel retention compared to those obturated using EB of Groups 2 and 4. Post retention to the over-prepared dowel spaces of Groups 4 and 5 was significantly higher than that recorded for the optimally-prepared ones of Groups 1-3. SEM images revealed traces of endodontic sealer and gutta-percha on the walls of the optimally-prepared dowel spaces.

CONCLUSION

Despite the adverse effect of endodontic sealers on the retention of fiber posts, the over-preparation of dowel spaces helps to improve the retention.     

Tissue reaction to Endométhasone sealer in root canal fillings short of or beyond the apical foramen

Objective

This study evaluated the response of periapical tissues to the endodontic sealer Endométhasone in root canal fillings short of or beyond the apical foramen.

Material and Methods

Twenty root canals of premolars and incisors of 2 mongrel dogs were used. After coronal access and pulp extirpation, the canals were instrumented up to a size 55 K-file and the apical cemental barrier was penetrated with a size 15 K-file to obtain a main apical foramen, which was widened to a size 25 K-file. The canals were irrigated with saline at each change of file. The root canals were obturated either short of or beyond the apical foramen by the lateral condensation of gutta-percha and Endométhasone, originating 2 experimental groups: G1: Endométhasone/short of the apical foramen; G2: Endométhasone/beyond the apical foramen. The animals were killed by anesthetic overdose 90 days after endodontic treatment. The individual roots were obtained and serial histological sections were prepared for histomorphological analysis (H&E and Brown & Brenn techniques) under light microscopy. The following parameters were examined: closure of the apical foramen of the main root canal and apical opening of accessory canals, apical cementum resorption, intensity of the inflammatory infiltrate, presence of giant cells and thickness and organization of the apical periodontal ligament. Each parameter was scored 1 to 4, 1 being the best result and 4 the worst. Data were analyzed statistically by the Wilcoxon nonparametric tests (p=0.05).

Results

Comparing the 2 groups, the best result (p<0.05) was obtained with root canal filling with Endométhasone short of the apical foramen but a chronic inflammatory infiltrate was present in all specimens.

Conclusions

Limiting the filling material to the root canal space apically is important to determine the best treatment outcome when Endométhasone is used as sealer.     

Quality of obturation achieved by an endodontic core-carrier system with crosslinked gutta-percha carrier in single-rooted canals

Objectives

The present study examined the quality of obturation in root canals obturated by GuttaCore, a gutta-percha-based core-carrier system with a cross-linked thermoset gutta-percha carrier, by comparing the incidence of gaps and voids identified from similar canals obturated by cold lateral compaction or warm vertical compaction.

Methods

Thirty single-rooted premolars with oval-shaped canals were shaped and cleaned, and obturated with one of the three obturation techniques (N = 10): GuttaCore, warm vertical compaction or cold lateral compaction. Filled canals were scanned with micro-computed tomography (micro-CT); reconstructed images were analysed for the volumetric percentage of gaps and voids at three canal levels (0–4 mm, 4–8 mm and 8–12 mm from working length). The roots were subsequently sectioned at the 4-mm, 8-mm and 12-mm levels for analyses of the percentage of interfacial gaps, and area percentage of interfacial and intracanal voids, using scanning electron microscopy (SEM) to examine negative replicas of root sections. Data were analysed with parametric or non-parametric statistical methods at α = 0.05.

Results

Both micro-CT and SEM data indicated that canals obturated with GuttaCore core-carriers had the lowest incidence of interfacial gaps and voids, although the results were not significantly different from canals obturated by warm vertical compaction. Both the GuttaCore and the warm vertical compaction groups, in turn, had significantly lower incidences of gaps and voids than the cold lateral compaction group.

Conclusions

Because of the similarity in obturation quality between GuttaCore and warm vertical compaction, practitioners may find the GuttaCore core-carrier technique a valuable alternative for obturation of oval-shaped canals.

Clinical Significance

The quality of obturation achieved by GuttaCore in single-rooted canals is not significantly different from that achieved by warm vertical compaction.     

Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

Objective

The aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars.

Material and methods

The amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris.

Results

ProTaper Universal files were significantly faster (p=0.0011) than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion.

Conclusions

ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris.     

The effect of root canal preparation on microleakage within endodontically treated teeth: an in vitro study

AIM: The purpose of this study was to evaluate the effects of smear layer and canal instrumentation on leakage in root-filled teeth. METHODOLOGY: Six groups (n = 12) of freshly extracted human canines and premolars with closed apices and single roots were used. Groups A, B, C, and D were instrumented with engine-driven rotary nickel-titanium MCXIM files and Groups E and F were instrumented with conventional stainless steel hand files. Groups A, C, and E were flushed with 3.0 mL of 17.0% REDTA to remove the smear layer prior to obturation. All teeth were flushed with 5.25% NaOCl, then obturated with AH-26 sealer and either the lateral condensation (Groups C-E) or thermomechanical compaction technique (Groups A and B). Copper wire was placed coronally in contact with the gutta-percha in each tooth and, after immersion in 0.9% NaCl solution, a 10 volt dc voltage was connected between each tooth and a stainless steel electrode. The current flow in the circuit was observed for 45 days. One way ANOVA and Duncan's Multiple Range Test were used to compare Groups A-F at time intervals of 10, 20, 30 and 45 days and identify statistically significant differences. RESULTS: Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine-driven NiTi files exhibited less leakage than hand-instrumented canals irrespective of obturation method. CONCLUSIONS: Smear layer removal is beneficial to root canal sealing. Obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals.     

Removal efficiency of propolis paste dressing from the root canal

Objetives

The aim of this study was to investigate through scanning electron microscopy (SEM) the cleaning of root canal walls after the use of experimental propolis or calcium hydroxide root canal dressings.

Material and Methods

Twenty single-rooted teeth were used. After conventional cleaning and shaping procedures and removal of the smear layer with 17% EDTA, the teeth were divided into four groups according to the medication used (N=5): Group I (control) - No drug, Group II - Calcium hydroxide dressing, Group III - Propolis paste A70D and Group IV - Propolis paste D70D. The medications were introduced into the root canals and maintained for 7 days, then removed with a K-file and 5 mL of 1% sodium hypochlorite irrigation. Finally, the canals were flushed with 2 mL of 17% EDTA for 3 min. For SEM analysis, the roots were cleaved and microphotographs from the middle third of the root canal were taken at 750x. The cleaning of the root canal walls was determined by the number of open dentinal tubules as verified with the software Image Tool 3.1. The statistical analysis was performed by ANOVA and Tukey''s test (p<0.05).

Results

The results showed no statistically significant difference between the calcium hydroxide and propolis groups.

Conclusions

The experimental propolis pastes presented acceptable physical characteristics to be used as intracanal medicaments.     

A microleakage study of gutta-percha/AH Plus and Resilon/Real self-etch systems after different irrigation protocols

The development and maintenance of the sealing of the root canal system is the key to the success of root canal treatment. The resin-based adhesive material has the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls. Moreover, the irrigation protocols may have an influence on the adhesiveness of resin-based sealers to root dentin.

Objective

The objective of the present study was to evaluate the effect of different irrigant protocols on coronal bacterial microleakage of gutta-percha/AH Plus and Resilon/Real Seal Self-etch systems.

Material and Methods

One hundred ninety pre-molars were used. The teeth were divided into 18 experimental groups according to the irrigation protocols and filling materials used. The protocols used were: distilled water; sodium hypochlorite (NaOCl)+eDTA; NaOCl+H₃PO₄; NaOCl+eDTA+chlorhexidine (CHX); NaOCl+H₃PO₄+CHX; CHX+eDTA; CHX+ H₃PO₄; CHX+eDTA+CHX and CHX+H₃PO₄+CHX. Gutta-percha/AH Plus or Resilon/Real Seal Se were used as root-filling materials. The coronal microleakage was evaluated for 90 days against Enterococcus faecalis. Data were statistically analyzed using Kaplan-Meier survival test, Kruskal-Wallis and Mann-Whitney tests.

Results

No significant difference was verified in the groups using chlorhexidine or sodium hypochlorite during the chemo-mechanical preparation followed by eDTA or phosphoric acid for smear layer removal. The same results were found for filling materials. However, the statistical analyses revealed that a final flush with 2% chlorhexidine reduced significantly the coronal microleakage.

Conclusion

A final flush with 2% chlorhexidine after smear layer removal reduces coronal microleakage of teeth filled with gutta-percha/AH Plus or Resilon/Real Seal SE.     

Comparison of lateral condensation and thermomechanically compacted warm alpha-phase gutta-percha with a single cone for obturating curved root canals

OBJECTIVE: To evaluate and compare the sealability and radiographic quality of root fillings in extracted teeth by using lateral condensation of gutta-percha or alpha-phase gutta-percha in conjunction with a single gutta-percha cone. STUDY DESIGN: A total of 108 single-rooted teeth were divided into 2 groups of 54 teeth based on canal shape. Canals were prepared to a minimum 0.055 taper and enlarged to a size 35 at the working distance. Irrigation was done with 17% EDTA and 2.5% sodium hypochlorite (NaOCl) to remove smear layer. One group was obturated by using cold lateral condensation of gutta-percha; the other group was obturated with thermomechanically compacted alpha-phase gutta-percha and a single cone of gutta-percha. Apical extrusion of sealer or gutta-percha was recorded. Sealability of each technique was assessed by dye penetration. The radiographic quality of obturation was also determined. RESULTS: Root canals filled with alpha-phase gutta-percha and a single cone had significantly more extrusion of sealer than canals filled by lateral condensation. Lateral condensation achieved significantly better scores for radiographic quality. There was no significant difference between the 2 filling techniques in terms of apical or coronal leakage. CONCLUSIONS: Thermomechanically condensed alpha-phase gutta-percha used in conjunction with a single gutta-percha cone had poorer radiographic quality than laterally condensed gutta-percha.     

EVALUATION OF APICAL MICROLEAKAGE OF TEETH SEALED WITH FOUR DIFFERENT ROOT CANAL SEALERS

Objectives:

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

Results:

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

Conclusions:

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

The use of glass ionomer as a root canal sealer—a pilot study

The use of a resin-based glass ionomer as an endodontic sealer was studied in vitro. The root canals of extracted single-rooted human teeth with mature apices were prepared using a stepback technique. Subsequently, the smear layer was removed with 40% citric acid and the canals obturated using lateral condensation of cold gutta-percha and a resin-based glass ionomer as the sealer. The relationship between the sealer and the wall of the root canal was studied using scanning electron microscopy. The shear bond strength of gutta-percha to this glass ionomer was also determined. Finally, the uptake of fluoride into the wall of the root canal was studied using scanning electron microprobe analysis after storage for 2 weeks, 1 month and 3 months following root filling with gutta-percha and glass ionomer cement. The results showed that removal of the smear layer allowed the sealer to enter some of the dentinal tubules. This was observed most frequently in the middle third of the root canal, where there was good adaptation of the sealer. The shear bond strength of gutta-percha to the glass ionomer sealer was not significantly different from that obtained between gutta-percha and a proprietary zinc oxide-eugenol endodontic sealer. The concentration of fluoride in the dentine in the coronal part of the root canal increased after obturation with gutta-percha and the glass ionomer sealer at every time interval. The increase in fluoride concentration varied widely between teeth. It is concluded that a resin-based glass ionomer cement may have potential as a root canal sealer.     

Comparison of the obturation of lateral canals by six techniques.

The following obturation techniques were compared on their ability to obturate lateral canals in vitro, lateral condensation (LC), continuous wave of condensation (CW), warm vertical condensation (WV), carrier-based thermoplasticized gutta-percha (CB), warm lateral condensation (WL), and vertically condensed high-temperature gutta-percha (HT). A root canal system with lateral canals in the coronal, middle, and apical thirds was prepared in resin blocks. Each block was obturated using each technique (n = 30, 15 each, with and without sealer). The length of gutta-percha and sealer in each of the lateral canals was measured with a measuring microscope and statistically compared. All techniques obturated all three levels of lateral canals with sealer. WV, CB, and CW were able to fill the lateral canals with gutta-percha significantly better when root canal sealer was used. WV, CB, CW, and HT filled the coronal and middle lateral canals significantly better with gutta-percha than LC or WL condensation. CB and CW filled the apical lateral canal significantly better with gutta-percha than HT, WV, WL, or LC.     

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique

Objectives

The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1.

Materials and methods

Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth.

Results

Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region.

Conclusions

These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system.

Clinical relevance

These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.     

The adaptation of mechanically softened gutta-percha to the canal walls in the presence or absence of smear layer: a scanning electron microscopic study

The objective of this study was to compare the adaptation of mechanically softened gutta-percha to the root canal wall in the presence and absence of smear layer. The root canals of 20 freshly extracted human maxillary incisors were cleaned and shaped. Prior to obturation, 10 root canals were irrigated with 20 ml of 50% citric acid followed by 20 ml of 5.25% sodium hypochlorite. All canals were obturated with mechanical compaction of gutta-percha and AH-26 sealer. After 72h, each tooth was fractured in half. Scanning electron microscopy demonstrated that the sealer had formed a continuous layer in contact with the canal walls, becoming progressively thinner towards the apex. The sealer pentrated into the dentinal tubules along with projections of gutta-percha only in those teeth without smear layer.