Comparison of Gutta-Percha Obturation Techniques in the Treatment of Wide Root Canals in Dogs

Capík I., S. Štvrtina: Comparison of Gutta-Percha Obturation Techniques in the Treatment of Wide Root Canals in Dogs. Acta Vet. Brno 2008, 77: 291-296. An in vitro study was conducted to compare gutta-percha obturation techniques of the developing incisors in dogs. Two perpendicular radiographic views were used for evaluation of apical and overall appearance of root canal obturation. Apical leakage technique was used to evaluate ability of each method to provide adequate apical obturation. The endodontic technique utilizing warm vertical condensation with chemically softened guttapercha in the apical region provided the best radiographic appearance without apical dye leakage. The same vertical obturation technique without the use of chemically softened gutta-percha in the apical region showed 33% dye leakage incidence. Lateral obturation techniques provided the least qualitative radiographic appearance to the endodontic fill and dye leakage incidence. Results of evaluation of quality of apical obturation of root canals based on X-ray examination and apical dye leakage resulted in the following conclusions: lateral obturation techniques used in this study have their limitations resulting from typical root canal anatomy; vertical obturation techniques showed better hermetic apical sealing, mainly in the case of vertical condensation of the chemically softened gutta-percha in the apical part of the root canal. Dog, immature adult incisors, endodontic, root canal, apical sealing Hundreds of animals experience traumatic dental damage every year. This involves not only crown or root fractures which result in direct impairment of anatomical tooth structures but also shocks, chemical or thermal damage which, without visible impairment of the tooth, cause damage to its most important part, the dental pulp. The aetiology of tooth fractures is multifactorial, including activity, behaviour, and accidental trauma (Fichtel 2000; Pavlica 1991). Bacteria in the root canal system are the primary cause of periapical periodontitis (Kakehashi et al. 1965; Möller et al. 1981). Healing of apical periodontitis involves a combination of disinfection of the root canal space through chemo-mechanical means (Byström and Sundqvist 1983, 1985) and sealing both the root canal and access to cavity with materials that prevent re-infection (Ray and Trope 1995). More than 50% of faulty endodontic treatments involve leaky root restorations. Because of that it is very important to select a suitable material and obturation technique which ensures that the complex system of apical delta of dog teeth is closed as tightly as possible. The correct approach to therapy requires not only good orientation in a range of different types of available materials and techniques involving obturation of root canals but also perfect knowledge of anatomy and physiology of the endodontic system and good understanding of respective pathological processes. Radiological examination of incisors, premolars and molars is impossible from two views perpendicular one to another. Incisors, premolars and molars may be radiologically viewed from the labio-lingual/palatal view but not from the mesio-distal one. Our experience with ACTA VET. BRNO 2008, 77: 291-296; doi:10.2754/avb200877020296 Address for correspondence: Doc. MVDr. Igor Capík, PhD. Clinic of Small Animals University of Veterinary Medicine Komenského 73, Košice 040 01 Slovak Republic Tel.: +421 915 984 607 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm developing incisors (i.e. teeth in dogs of 8 to 14 months of age) confirms the following anatomical characteristics: 1. The crown size is small in relation to the labio-lingual diameter of the root canal, thus preventing sufficient access to cavity preparation. 2. The walls of the root canal from the mesio-distal view form an approximately elliptical shape with the widest diameter in the middle third of the root canal. 3. The apical area of the root canal is divergently separated in some incisors under 1 year of age. Different obturation materials and techniques are used to obturate root canals in the dog including gutta-percha points using lateral or vertical condensation, chloroform dip technique, Obtura II system, silver points etc. The purpose of this study was to evaluate and compare radiologically the effectiveness of root canal obturation from two perpendicular views and the apical dye leakage of obturation techniques using gutta-percha as a root filling material. Materials and Methods The study was conducted on incisors obtained from cadavers of 7-12-month-old dogs. Before inclusion in the experiment, the teeth were examined clinically and radiologically. We selected only teeth with a wide root canal, closed apex and absence of root fractures or any other pathological changes. A total of 36 teeth were used. To exclude any variability of procedures, all X-ray pictures were taken and all the fillings were made by the same person. The teeth were divided into 5 groups, six in each, and were obturated with gutta-percha (GP) cones. In the 1st group of incisors by Triadan (1.201 3 and 3.401 3) we used the technique of cold lateral condensation (LC). Standardised GP cones of sizes 40 90 (ISO standard) according to the real width of the root canal were used as master cones. The lateral condensation was ensured by spreaders of the size 15 or 20 ISO. The surplus GP was removed from the crown zone by a warmed device and vertically condensed by a wide plugger. The 2nd group of incisors consisted of teeth obturated also by lateral condensation as in the first group, but a combination of GP and root canal cement (Endomethasone N, Septodont) was used (LC-C). The procedure was the same as used in the 1st group but before the obturation we applied a thin cement layer to the canal and to individual GP cones. Comparison of the results obtained in the 1st and 2nd group allowed us to determine the influence of the cement layer on the tightness achieved by lateral condensation technique. In the 3rd group of incisors we used lateral condensation of heat-softened GP (WLC warm lateral condensation). This group comprised teeth contralateral to those used in the 1st group in which we expected very similar structure of the canal. We observed differences in the quality of tightness achieved by respective techniques. In the 4th group we used the technique of warm vertical condensation back packing (WVC). The GP cones were shortened to 4 mm, inserted into the root canal and condensed using a warm plugger of the appropriate diameter. Obturation of root canals of teeth from the 5th group was carried out by the technique of back packing by halothane-softened GP (BP-H). The principal GP cone was shortened to 5 mm and the apical 4 mm were submerged in halothane for 10 s. Immediately after that the cone was inserted and condensed vertically by a plugger of appropriate diameter. Subsequently, the remainder of the root canal was obturated by warm vertical condensation as in the 4th group. After the obturation of root canals, two X-ray projections in directions perpendicular to each other were obtained of all teeth from individual groups. They were scanned and divided within each group by one examiner to four subgroups according to the quality of root obturation (1 excellent, 2 very good, 3 good and 4 poor obturation quality). The cement layer on roots of all teeth was coated with a lacquer film with the exception of the apical zone which was left uncoated. Then the teeth were fixed in a dental wax plate and their apical parts were submerged in gentian blue up to the cement-enamel junction and left there for two weeks. This allowed us to assess the extent of penetration of the fluid through the apical delta and adjunct canals in the apical third into root canals at various ways of obturation. The extent of passage of the liquid was evaluated on sections of the roots. The teeth were cut longitudinally using a diamond saw. The sections were photographed and the extent of penetration of the dye to the root canal was assessed. The quality of obturation was evaluated on the basis of the degree of replication of the canal working length, surface adaptation and homogeneity of gutta-percha and resistance of obturation to penetration of the dye. The results of root canal obturation were statistically evaluated using ANOVA test.