Effect of gravity and capillarity on human saliva penetration in coronally unsealed obturated root canals

AimThe purpose of this study was to evaluate the effect of gravity and capillarity on penetration of human salivary bacteria into the entire length of obturated root canals, and to demonstrate the dye penetration configuration.Materials and methodsFifty single-rooted premolars were decoronated, prepared to a standardized length of 15 mm, instrumented, and randomly divided into two groups (A and B) of 25 teeth each. Each group consisted of experimental (15 samples) and negative and positive controls (five samples each). The experimental groups were obturated with gutta-percha and root canal sealer. The positive control groups were obturated with a single cone of gutta-percha and root canal sealer. The outer surfaces (except for the apical 2 mm) were covered with two layers of nail varnish. An apparatus containing Brain Heart Infusion broth was designed, in which the teeth were placed. The samples in Group A were placed upside down, while Group B was placed normally. The coronal portions of the samples were placed in contact with fresh saliva. The number of days required for bacteria to penetrate the entire length of canals was determined. The samples were then immersed in India ink to determine the dye penetration configuration. Data were analyzed using Student’s t-test.ResultsThe extent of dye penetration was significantly greater in Group B compared to Group A, and they were in a pattern rather than linear form.ConclusionsGravity and capillarity insignificantly affected bacterial leakage. Although gravity and capillarity did not affect bacterial penetration when applied to the coronal access of endodontically treated teeth, it seems that they can promote penetration of India ink into the canal after the bacterial test on the same tooth.     

Comparison of the quality of obturation following endosonic versus hand instrumentation

This study was undertaken to compare the quality of root canal obturation following preparation by endosonic or hand instrumentation. Forty single-canal, extracted lower premolar teeth were selected. One group of 20 teeth was prepared using a standard step-back technique, the other 20 teeth were prepared with an ultrasonic machine. The groups were subdivided, with two operators preparing 10 teeth of each group. The teeth were obturated by a third operator using cold laterally condensed gutta percha. The root apices were then immersed in methylene blue dye for 48 h and the teeth sectioned longitudinally. Image analysis recorded the amount of sealer and void within the obturated canal. The linear distance of dye penetration was measured to provide an indication of apical seal. Examination of the root canal shape resulting from the different preparation techniques used was also undertaken. No significant difference was noted in the percentage of sealer and void present in the root canals obturated after endosonic or hand instrumentation. There was a slightly greater although not significant increase in the degree of linear penetration of dye in canals prepared endosonically. The endosonic technique used in this study appeared to produce a canal preparation of slightly less continuous taper than that obtained with hand preparation.     

Obturation of root canals with different sealers using non-instrumentation technology

AIM: To evaluate and compare the sealing quality of hand- or vacuum-obturated root canals after hand preparation or hydrodynamic cleansing of root canals, respectively. METHODOLOGY: After assessing root curvature, 96 single-rooted deep-frozen teeth were divided into eight comparable groups. The root canals of four groups were instrumented with the balanced force technique. The remaining uninstrumented teeth were connected to a reduced-pressure device (NIT) and the root-canal system perfused with 2.5% NaOCl under alternating pressure fields. This dissolved the pulpal tissues and removed debris from the root-canal system. The canals of the hand-instrumented groups were obturated using the cold lateral condensation method with guttapercha and one of four different sealers (AH26, AH Plus, Apexit and Pulp Canal Sealer EWT). The teeth treated with the alternating pressure device (NIT) were obturated by a vacuum obturation method (NIT) with the same four sealers. The quality of the coronal seal was assessed using a dye penetration method. In order to minimize errors the roots were perfused with water before exposure to the dye, under vacuum. The teeth were then rendered transparent and the depth of penetration of the dye between the wall of the canal and the obturating material was measured with a stereomicroscope. RESULTS: The canals cleaned and filled by NIT showed statistically significantly less dye penetration than those obturated by lateral condensation (P < 0.05). Within the NIT group, Pulp Canal Sealer EWT exhibited significantly more dye penetration than Apexit. Amongst the control lateral condensation groups no significant differences were found between the various sealers. CONCLUSIONS: The present investigation demonstrated the validity of the NIT obturation method in combination with commonly used root-canal sealers.     

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.     

A standardized technique for linear dye leakage studies: immediate versus delayed immersion times

A dye leakage study was performed in vitro to compare the extent of leakage into root canals obturated with gutta-percha following immediate versus delayed immersion in Indian ink. Sixty extracted human teeth with single canals were instrumented and obturated with gutta-percha and sealer. Each group of 20 teeth was then immersed in the ink either immediately after obturation or after a delay of 1 or 7 days. After 7 days in Indian ink, the teeth were rendered transparent by clearing, and the linear extent of ink penetration was measured with a stereomicroscope. Complete leakage was observed in the two positive control teeth, and no leakage was evident in the two negative controls. Statistical analysis of the results indicated that there was no significant difference in leakage between the three experimental groups.     

Sealing capacity in vitro of thermoplasticized gutta-percha with a solid core endodontic filling technique

Abstract— This study assessed the sealing capacity of two endodontic gutta-percha filling techniques. Thirty-four single-rooted fully developed teeth were endodontically accessed, instrumented and randomly divided into two experimental groups ( n =12) and two control groups ( n =5). In Group A, root canals were obturated using a solid core thermoplastic technique (Densfil), in Group B and Group C (negative control) canals were obturated with laterally condensed gutta-percha, and in Group D (positive control) canals were left un-obturated. AH-26 was used as the sealer. Two days later, the teeth were conventionally prepared for testing apical and coronal leakage, immersed in india ink for 5 days and subsequently cleared. The linear coronal and apical extent of dye penetration was measured under a light dissecting microscope. The mean apical leakage for Group A was 1.39 mm, and for Group B 2.76 mm, whereas the mean coronal leakage for Group A was 2.87 mm, and for Group B 4.03 mm. The differences between the groups were not statistically significant (P>0.05).     

Sealing ability of thermoplasticized gutta-percha in root canal obturation using a sectional vs. a single-phase technique

Properly prepared straight root canals of freshly extracted maxillary canines and central incisors were used to evaluate the sealing ability of the sectional thermoplasticized gutta-percha obturation technique, with or without sealer and the single-phase thermoplasticized gutta-percha filling technique. The teeth were divided into 3 groups (A, B, C) of 20 teeth and were obturated using the 3 thermoplasticized gutta-percha techniques. Group A: single phase with sealer; group B: sectional technique without sealer; and group C: sectional technique with sealer. The obturated teeth were immersed in India ink for 3 days followed by clearing procedures. The teeth were then examined under a stereo microscope and the linear leakage was recorded. Statistical unpaired Student's t-tests showed significantly less dye penetration in teeth obturated using the sectional technique with sealer (group C) than in teeth obturated with the single-phase technique with sealer (group A) or the sectional technique without sealer (group B).     

Evaluation of the Trifecta obturating technique

Abstract – 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.     

Effect of apical resections and reverse fillings on Thermafil root canal obturations

This in vitro dye leakage study examined the influence of apical root resection and reverse amalgam fillings on the apical seal of root canals obturated with Thermafil. Fifty human canine teeth were instrumented and obturated with either laterally condensed gutta-percha or Thermafil using Roth's zinc oxide-eugenol Type I regular sealer. After 24 h, one of the following additional procedures was performed on 30 of the teeth: 2-mm apical resection, 4-mm apical resection, and 2-mm apical resection plus reverse amalgam filling 2 mm in depth and diameter. The external root surfaces were coated with enamel paint and the teeth were exposed to 1% methylene blue dye at 37 degrees C for 2 wk. The roots were split longitudinally and the depth of linear dye penetration was measured through a stereozoom microscope. Statistical analysis showed no significant differences in the linear dye penetration among the various groups of teeth.     

Long-term obturation quality using noninstrumentation technology

The aim of the study was to evaluate and compare the sealing quality of hand- or vacuum-obturated root canals after hand instrumentation or noninstrumentation cleansing. A total of 60 single-rooted teeth were divided into six comparable groups. The root canals of three groups were instrumented with the balanced-force technique and obturated with gutta-percha condensation. The remaining teeth were cleansed and filled using noninstrumentation technology and the same sealers as with hand instrumentation (AH Plus, Apexit, Pulp canal sealer EWT). After aging the quality of coronal seal was assessed with a dye penetration method after perfusion with the dye under vacuum. The results of this study indicated superior sealing of the machine-filled roots (noninstrumentation technology), compared with laterally condensed conventionally filled root canals.     

Sealing ability of thermoplasticized gutta-percha in root canal obturation using a sectional vs. a single-phase technique

Abstract Properly prepared straight root canals of freshly extracted maxillary canines and central incisors were used to evaluate the sealing ability of the sectional thermoplasticized gutta-percha obturation technique, with or without sealer and the single-phase thermoplasticized gutta-percha filling technique. The teeth were divided into 3 groups (A, B, C) of 20 teeth and were obturated using the 3 thermoplasticized gutta-percha techniques. Group A: single phase with sealer; group B: sectional technique without sealer; and group C: sectional technique with sealer. The obturated teeth were immersed in India ink for 3 days followed by clearing procedures. The teeth were then examined under a stereo microscope and the linear leakage was recorded. Statistical unpaired Student's t-tests showed significantly less dye penetration in teeth obturated using the sectional technique with sealer (group C) than in teeth obturated with the single-phase technique with sealer (group A) or the sectional technique without sealer (group B).     

Does cold burnishing gutta-percha create a better apical seal?

This study investigated the seal created by cold burnishing the gutta-percha exposed after apical root resection of endodontically treated teeth. Sixty single-rooted extracted human teeth with a single straight canal were divided into four experimental groups of 15 teeth each. In two of the experimental groups the canals were instrumented and obturated well with laterally condensed gutta-percha and sealer. The remaining two groups were instrumented and poorly obturated with laterally condensed gutta-percha and sealer. The apical 2 mm of all the teeth were then resected and the effect of cold burnishing the exposed gutta-percha was investigated using a linear dye penetration technique. Under the condition of this study, cold burnishing gutta-percha after apical root resection of a well-obturated root canal resulted in a poorer apical seal than if no burnishing were performed. Cold burnishing the exposed gutta-percha after apical root resection of poorly obturated root canals improved the apical seal as compared with nonburnished poorly obturated canals.     

Extent of microleakage in relation to root canal morphology

The purpose of this study was to study with standardized methods the length and extent of the microleakage developing around the root canal fillings. The preparational errors were evaluated in twenty straight and curved root canal using computer graphic analysis. The step back technique was used for root canal preparation. The shape of the instrumented root canals were analyzed macroradiographically in order to evaluate unwanted procedural root canal deformities. The root canals were obturated with lateral condensation technique using AH-26 sealer and guttapercha points. After the teeth having been made transparent a silver nitrate penetration test was performed in vacuum and both the linear dye penetration and the extent of dye penetration surface area were measured from four directions with computer assisted digitized method. The linear dye penetration values were higher in straight root canals than in curved ones: 2.22 + 1.17 mm and 1.81 + 1.24 mm respectively. The dye penetration surface area was slightly also larger in straight than in curved root canals: 1.3 +/- 0.71 mm2 vs. 1.06 +/- 0.5 mm2. Nevertheless the differences were statistically non significant. In curved root canals the highest dye penetration values were measured at the inner curvature of the canals. This findings was also corroborated by a coincidence test.     

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.     

The use of 3D computerized reconstruction for the study of coronal microleakage

AIM: The purpose of this study was to evaluate a new method for studying coronal microleakage associated with root-filled teeth. METHODOLOGY: Twenty human mandibular posterior teeth were prepared chemomechanically with the stepback technique and then divided into two groups of 10 teeth each. The canals were filled using lateral condensation of gutta-percha points; Roth's 801 was used as a sealer for the first group, and Ketac-Endo for the second. After 48 h, the temporary fillings in the access cavities were removed, the roots coated with three layers of nail polish and then the teeth were exposed to artificial saliva for 40 days. Subsequently, the crowns of the teeth were placed into Indian ink for 4 days before the coating was removed and the teeth embedded in a two-phase polyester resin. Serial cross sections were taken from each specimen using a microtome, and each cross section photographed under a stereoscopic microscope. The photographs of the cross sections were digitized using an image scanner and the contours of the external surface of the teeth, the obturated root canals and the boundaries of dye penetration were followed. Finally, a three-dimensional surface representation was achieved using the triangulation method. RESULTS: Although the sample size and the experimental methods were not designed to form valid groups, the results showed that all roots obturated with Ketac-Endo sealer had dye microleakage, whilst only three teeth of the Roth's 801 group had dye microleakage. CONCLUSIONS: The 3D reconstruction of dye microleakage proved to be an interesting method and a useful tool for the evaluation of coronal microleakage when using different types of root canal sealers.     

A comparison of laterally condensed gutta-percha, thermoplasticized gutta-percha, and mineral trioxide aggregate as root canal filling materials

The purpose of this study was to evaluate the potential of using mineral trioxide aggregate as a root canal filling material by comparing its apical sealing ability with that of laterally condensed gutta-percha with sealer and high-temperature thermoplasticized gutta-percha with sealer in extracted bovine teeth. Sixty bovine incisors with single canals were prepared in a standard manner using LightSpeed instruments, randomly divided into three groups of 20 teeth, and obturated. The sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 3 days. The teeth were cleared, and the linear extent of dye penetration was measured with a stereomicroscope. Data were analyzed by the Kruskal-Wallis one-way ANOVA followed by Dunn's test. Canals filled with laterally condensed gutta-percha or thermoplasticized gutta-percha showed significantly less apical dye penetration than canals obturated with mineral trioxide aggregate (p < 0.001). There was no significant difference in leakage between the laterally condensed group and the thermoplasticized group. The results suggest that gutta-percha obturation may provide an apical seal that is superior to MTA.     

Assessment of coronal microleakage of three materials used in endodontically treated teeth

This study compared the coronal microleakage of three restorative materials used to seal the access cavity in root treated teeth. Thirty six teeth were prepared and three experimental groups were obturated and the access cavity filled with different materials; Group A--Intermediate Restorative Material, Group B--Fuji II and Group C--Dyract AP. Microleakage was assessed by Indian ink penetration. The mean coronal dye leakage for Group A was 0.895 mm, for Group B 1.914 mm and for Group C 3.245 mm. There was significantly (p < 0.05) more dye leakage in teeth restored with Dyract AP compared to those with Fuji II or IRM.     

Leakage associated with intermediate restorative material and glass-ionomer cement retrograde fillings: a human and sheep teeth comparison with 2 different aging procedures.

OBJECTIVES: Leakage around retrograde fillings is an important cause of endodontic surgery. This in vitro study sought to compare the following: (1) methylene blue dye leakage linked to retrofillings in human and sheep teeth with the degree of dye penetration when intermediate restorative materials and Chemfil were used as retrofillings, (2) the apical microleakage in filled with that in unfilled root canals, and (3) 2 storage techniques, incubator-based and subcutaneous implantation in rats. STUDY DESIGN: Tested were 198 human and 196 sheep teeth that were retrofilled with intermediate restorative material or Chemfil, then stored in an incubator or subcutaneously in rats for 10, 20, and 30 days before immersion in methylene blue dye for 24 hours. Linear dye penetration was evaluated, and the results were statistically analyzed by means of analysis of variance. RESULTS: Leakage between sheep and human teeth was significantly different (P <.05). Chemfil had significantly less leakage than intermediate restorative material after storage in rat (P <.05) for up to 20 days, but not after 30 days. No differences were found between leakage of unfilled and filled human root canal teeth. CONCLUSIONS: The sheep incisor is a poor experimental model of the human tooth, and both aging procedures demonstrate extensive leakage of retrofilling materials after long-term storage.     

In vitro evaluation of three techniques to obturate 0.06 taper canal preparations

The aim of this study was to evaluate the ability of three obturation methods to seal root canals prepared using 0.06 taper rotary instruments. Forty-five extracted human single-rooted teeth were instrumented with 0.06 taper Profile nickel-titanium rotary files and randomly divided into three experimental groups containing 15 teeth each. The first group was obturated using the System B technique with 0.06 taper standardised gutta-percha points, the second group was obturated using the System B technique with non-standardised MF gutta-percha points, the third group was obturated by cold lateral condensation technique using standardised 0.02 taper master gutta-percha points. Apical leakage of the roots was evaluated by dye penetration using a stereomicroscope after sectioning the roots. The group obturated using System B and 0.06 taper gutta-percha points showed the least dye penetration. However, the difference in the linear extent of dye penetration was not statistically significant.     

ProTaper简化预备法的根尖微渗漏实验研究

目的观察ProTaper简化预备法的根尖微渗漏,评价其根尖的封闭性能。方法 60颗离体成人患牙,分成2组。实验组30颗牙标本采用ProTaper机动系统简化预备和0.06锥度牙胶尖垂直加压充填根管,对照组30颗牙标本采用逐步后退法0.02锥度不锈钢锉预备和0.02锥度牙胶尖冷侧方加压充填根管,经透明标本染料渗透技术后,测量根尖部染料渗透的距离。结果实验组根尖染料的渗透距离均值0.60 mm,标准差0.29 mm,对照组根尖染料的渗透距离均值1.18 mm,标准差0.83 mm,2组根尖染料的渗透距离差异有统计学意义(P<0.05)。结论 ProTaper简化法预备根管配合相应锥度牙胶尖充填其根尖的封闭性能良好。