Linear Dye Leakage Research Articles

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

The objective of this study was to compare the effects of a flame-heated endodontic plugger, an electrically-heated endodontic spreader, Peeso reamers, and GPX burs on the apical seal when gutta-percha was removed from the root canal for post space preparation. Eighty-nine human canines were instrumented and obturated with gutta-percha and sealer to a standardized working length of 15 mm. An 11-mm segment of gutta-percha was removed from the roots in each of the four experimental groups of 20 teeth to simulate post space preparation. The teeth were immersed in India ink for 7 days and rendered transparent. The extent of linear dye leakage was measured with a stereomicroscope. There was no statistically significant difference in linear dye leakage among any of the experimental groups when 4 mm of gutta-percha remained.

Sealing ability of sectional injection thermoplasticized gutta-percha technique with varying distance between needle tip and apical foramen.

The purpose of this investigation was to evaluate the influence of the distance of the needle tip from the apical foramen on the apical seal and the length control of the root filling material when thermoplasticized gutta-percha is injected using a sectional injection technique. Ninety-nine human single-rooted mandibular incisors and permanent premolars with straight canals were divided into three equal Groups A, B and C. In Group A the teeth had relatively the wider root canal, in Group C the narrowest, while in Group B root canal size was intermediate. The root canals of all teeth were prepared with a step-back technique. Roots of Group A were instrumented to a Size 70 4 mm short of the working length, while roots of Groups B and C to a Size 70 6 mm and 8 mm short of the working length, respectively. The teeth of all groups were covered with aluminium foil and embedded in acrylic blocks. After the placement of sealer (Roth 811) the root canals of all teeth were obturated with injection-molded thermoplasticized gutta-percha using a three-stage sectional technique. The roots remained in India ink for three days and then cleared by successive immersion in nitric acid, ascending grades of alcohol and finally in xylene. The linear dye penetration and the linear apical underextentionion of the root canal filling were measured by two independent examiners under a stereo microscope. There was no significant difference in the linear dye leakage between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of three silicone-based materials as potential retrograde fillings in surgical endodontics

Endodontic therapy has played an important role in maintaining the integrity of the natural dentition as a fully functional and esthetic masticatory apparatus. Although the sealing of the root canal system is usually accomplished by the conservative endodontic approach, cases which have failed or which involve perforations, broken instruments, or post-crown restorations are almost always treated surgically by using zinc-free amalgam as a retrograde filling material. However, the literature is controversial concerning the health risks and benefits of this material. For this reason, the study presented here was initiated to evaluate the potential of (a) a medical grade silicone-titanium mesh compound; (b) Endo-Fill (Lee Pharmaceuticals, El Monte, CA); and (c) an experimental expanding Endo-Fill (Lee Pharmaceuticals) as alternatives to amalgam. The three silicone-based materials and amalgam were compared for linear apical dye leakage. The leakage study involved 80 teeth which were instrumented, obturated, and prepared surgically for one of the four test materials. Either the teeth were placed immediately into 1% methylene blue dye or the material was allowed to set for 24 h before placement into the dye. Endo-Fill showed significantly less leakage than did the other materials in both the immediately placed and the 24-h set groups. On the other extreme, the experimental expanding Endo-Fill allowed significantly more dye penetration than did amalgam and the other silicone variations.

The sealing ability of the thermafil obturation technique

Forty straight canals of maxillary canines and 40 curved canals in 20 mesial roots of mandibular molars were instrumented and randomly assigned to two groups of 40 canals each. For the experimental group, the canals were obturated using the Thermafil obturation technique. Lateral condensation was used for the obturation of the control group. Kerr pulp canal sealer was used in both group. The specimens were stored in 100% humidity for 1 wk. All teeth were suspended in black India ink for 14 days and decalcified in 5% nitric acid over a 2-day period. The teeth were then dehydrated in a graded series of alcohol to 100%. Methyl salycilate was used to clear and store the teeth for 48 h. Linear dye leakage measurements showed that canines obturated with the lateral condensation technique leaked significantly less than those obturated using the Thermafil technique (p = 0.02). The difference was not statistically significant in the molar roots.

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.