The sealing ability of injection-moulded thermoplasticized gutta-percha

The influence of smear layer in lateral channels filling

This in vitro study evaluated the ability of a warm gutta-percha obturation system Thermafil to fill lateral channels in presence/absence of smear layer. Forty single-rooted extracted human teeth were randomly divided into two groups for which different irrigation regimens were used: group A, 5 ml of 5% NaOCl + 2.5 ml of 3.6% H(2)O(2); group B, 5 ml of 5% NaOCl 5% + 2.5 ml of 17% ethylenediamine tetraacetic acid. A conventional crown-down preparation technique was employed. Obturation was performed using epoxy resin-based cement (AH Plus) and a warm gutta-percha plastic carrier system (Thermafil). Specimens were cleared in methyl salicylate and analyzed under a stereomicroscope to evaluate the number, length, and diameter of lateral channels. Lateral channels were identified in both groups at medium and apical thirds. Additional samples were prepared for scanning electron microscopy inspection to confirm the presence of smear layer in group A, and the absence of smear layer in group B. All lateral channels resulted filled in both groups. No statistically significant differences regarding number, length, and diameter were observed between the two groups. Smear layer did not prevent the sealing of lateral channels.

Smear layer influence on the apical seal of four different obturation techniques

The purpose of this study was the in vitro evaluation of four techniques for the obturation of the root canal system in the presence or absence of a smear layer. Ninety-six human upper central incisors were instrumented using the pressureless crown-down technique and irrigated with 5.25% NaOCl. The teeth that had the smear layer removed were irrigated with this solution in combination with 17% EDTA. The teeth were obturated with lateral condensation with an accessory or standardized cone as the main cone, with vertical condensation of warm gutta-percha or with thermoplasticized injectable gutta-percha. Apical leakage was assessed by measuring the linear penetration of methylene blue dye with a stereomicroscope. The results showed no significant differences in the degree of leakage with and without the smear layer when the samples were considered as a whole. However, when the groups were assessed separately, teeth in the lateral condensation with an accessory main cone group and teeth in the thermoplasticized group leaked less with a smear layer present. In contrast teeth with lateral condensation and a standardized main cone leaked more with a smear layer present. In the vertical condensation groups there was no difference attributable to the smear layer.

Leakage associated with single or multiple increment backfill with the Obtura II gutta-percha system

The purpose of this in vitro study was to compare dye leakage between canals backfilled in a single increment and canals backfilled in multiple increments using the Obtura II system with two different sealers. Sixty extracted single canal teeth were decoronated, cleaned, and shaped. After master cone fit and placement of either Roth 801 or AH26 sealers, the canals were down-packed to 4 mm from working length. The teeth were then divided into 4 groups of 15: group 1--Roth 801 sealer with 1 increment of Obtura II back-fill; group 2--Roth 801 sealer backfilled in 4- to 5-mm increments; group 3--AH26 sealer with 1 increment of backfill; and group 4--AH26 sealer backfilled in 4- to 5-mm increments. After sealer set, the teeth were apicected 5 mm from working length. The apices were discarded. The coronal segments were coated with two layers of fingernail polish, except for the resected apical end. The teeth were immersed in Pelikan ink for 5 days. The teeth were then decalcified, dehydrated, and rendered transparent in methylsalicylate. Dye penetration was measured on four surfaces of each root. The mean measurements of each tooth were averaged for each group. Leakage of group 1 was 6.69; group 2, 5.39; group 3, 5.71; and group 4, 5.02. Differences were not statistically significant (p > 0.05). This study suggests that it may be clinically acceptable to backfill canals up to 10 mm in a single increment using sealer and the Obtura II gutta-percha system.

Area-metric analysis of dye leakage for evaluation of sealing ability of root canal obturation techniques

Root canal sealing ability of obturation techniques has been assessed in vitro with various methods. The majority of the methods employ microleakage tracers and particularly dyes. In vitro measurements of dye penetration are either linear or volumetric. Area-metric analysis is a three dimensional registration method of dye leakage. The purpose of the present study was to evaluate in cleared teeth area-metric analysis as opposed to linear analysis of dye penetration. Forty freshly extracted single rooted human teeth were used. Instrumentation was carried out using Hedstroem files with a step back technique. The root canals were obturated using Roth sealer and qutta-percha cones and lateral condensation technique. The roots were then subjected to dye leakage tests under vacuum of 50 mmHg for 20 min. India ink was used as the tracer. The roots were randomly divided in two groups. In Group A the roots were cleared and linear measurements of the dye penetration were recorded The roots in Group B were ground stepwise transversally and subjected to area metric analysis. The results showed that area-metric analysis enabled sufficient recordings of the dye leakage patterns and the volume of the dye penetration could also be calculated.

Sealability of the Trifecta technique in the presence or absence of a smear layer

The aim of this in vitro study was to assess the sealability of a recently introduced thermoplasticized gutta-percha technique (Trifecta, Hygenic Corp., OH, USA) in the presence or absence of a smear layer. A total of 100 teeth with single straight root canals were included in the study. The teeth were decoronated and the canals prepared with a modified double-flared technique under constant irrigation with 2.5% sodium hypochlorite solution. The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 10 file. Four teeth were discarded for technical reasons and the remaining 96 allocated randomly into two groups of 44 teeth and a group of eight teeth which acted as controls. Canals in group 1 were obturated randomly with either cold lateral condensation of gutta-percha or with the Trifecta technique. Canals in Group 2 were rinsed with 17% REDTA to remove the smear layer and then obturated with lateral condensation or the Trifecta technique. All teeth were suspended in India ink for 9 days, demineralized, and rendered transparent prior to the assessment of apical linear dye penetration. Apical extrusion of sealer and gutta-percha occurred commonly but there was no significant difference between the four obturation groups. However, overall, there was significantly more extrusion of sealer with the Trifecta technique compared with lateral condensation (P < 0.05). The majority of canals (79 out of 88) had no evidence of apical leakage and there was no significant difference between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation of injected thermoplasticized gutta-percha in the absence of the dentinal smear layer

The adaptation of thermoplasticized, injected gutta-percha to prepared dentine devoid of smear layer was examined with SEM. Findings indicate a penetration of gutta-percha into the patient dentinal tubules with or without root canal sealer. The clinical implications of these findings are discussed.

Endodontic leakage studies reconsidered. Part I. Methodology, application and relevance

An increasing number of endodontic leakage studies have been published. In the 1990 volumes of Journal of Endodontics and International Endodontic Journal, there was one leakage study to every 4.3 scientific articles. The most popular method was linear measurement of tracer (dye or radioisotope) penetration along a root filling. Comparing some data on linear measurement of dye penetration following the cold lateral condensation of gutta-percha that were published between 1980 and 1990, a high level of variation has been found, although the experimental methods used in these studies were quite similar. In almost all studies evaluating various techniques, the cold lateral condensation technique has been used as a standard control for comparison. The reliability of these results is questionable. The problems with such studies are discussed. It seems that more research should be done on leakage study methodology, instead of continuing to evaluate the sealing ability of different materials and techniques by methods that may give little relevant information.

Clinical experience in root canal obturation by an injection thermoplasticized gutta-percha technique

Forty-one human teeth with a total of 71 root canals were obturated with the high-temperature injected thermoplasticized technique (Obtura). Patients were recalled 6 to 36 months postoperatively. Cases were evaluated on the basis of clinical and X-ray findings. The success rate was 93.1%.

Adhesion of root canal sealers to bovine dentine and gutta-percha

The adhesive properties of eight root canal sealers, applied as a thin layer between a dentine and a gutta-percha surface, were investigated. Tensile bond strengths ranged from 0.02 MPa (Sealpex) to 2.38 MPa (AH26). Inspection of fractured surfaces indicated failure of adhesion to dentine (Tubli-Seal) and to gutta-percha (AH26, Diaket) as well as failure of cohesion (CRCS, Kloroperka N-O, ProcoSol, rosin chloroform, Sealapex). Pretreatment of the dentine surface with EDTA caused a significant increase in bond strength for ProcoSol, rosin chloroform, Sealapex, and Tubli-Seal.

Sealing ability of materials used as retrograde root fillings in endodontic surgery

The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light-cured composite resin, dentine bonding agent, and light-cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light-cured composite resin, light-cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta-percha, amalgam plus cavity varnish and EBA cement.

Sealing ability of amalgam used as a retrograde root filling in endodontic surgery

A dye penetration technique was used to investigate the sealing ability of amalgam retrograde root fillings in vitro. A factorial design was employed to determine the effect of amalgam fillings of 1, 2 and 4 mm in length with and without prior filling of the canals with gutta-percha. The results were compared with a group of teeth filled with laterally condensed gutta-percha alone and another with laterally condensed gutta-percha plus root resection but with no retrograde filling. It was concluded that increasing the length of the amalgam filling did not improve the seal, that prior filling of the canal did not improve the seal, that retrograde root fillings were no worse than laterally condensed gutta-percha alone and that root resection of teeth filled with laterally condensed gutta-percha without retrograde filling was no worse than those filled with laterally condensed gutta-percha without root resection or retrograde root filling.