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

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

0099-2399/91/1708-0389/03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodontists Printed in U.S.A. VOL. 17, NO. 8,...

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0099-2399/91/1708-0389/03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodontists

Printed in U.S.A.

VOL. 17, NO. 8, AUGUST 1991

CLINICAL ARTICLES Clinical Experience in Root Canal Obturation by an Injection Thermoplasticized Gutta-percha Technique Victor Sobarzo-Navarro, DDS

a-pex; Ellman, NY). An X-ray and new endometric measurements were taken and compared, thus excluding fluctuations in measurements. The root canals were enlarged with K files (Vereinigte Dentalwerke, Mtinchen, Federal Republic of Germany) by using a step-back preparation technique. The cervical portion and the midportion of the canals were enlarged with Gates Glidden burs (Maillefer, Ballaigues, Switzerland) in order to permit a better application of the Obtura applicator tip during the root canal obturation. Before obturation of the root canal with the thermoplasticized gutta-percha injection technique, it is advisable to check the apical portion of the root canal for an apical barrier, especially in cases where the apical foramen is open (Blunderbus). This was done by using a #15 K-file or sterile paper points or with endometric measurements. After the presence of an apical barrier was demonstrated, a small portion of root canal sealer was applied to the root canal walls. Tubli Seal (Kerr Sybron, Romulus, MI) and later Sealapex (Kerr) were used for this purpose. The next step was to apply a small portion of thermoplasticized gutta-percha which was vertically compacted with an endodontic plugger (Maillefer) moistened with 70% methyl alcohol to prevent the gutta-percha from adhering to the instrument. At this point, if a temporary post crown was not necessary, the root canal could be completely obturated with the thermoplasticized gutta-percha. After having taken an X-ray and having made sure that the gutta-percha filling was correctly in place, a temporary filling was done to protect the occlusal surface of the treated tooth. Some zinc oxide cement was placed over the gutta-percha filling, followed by a sterile cotton pellet and Cavit (Espe GmbH, Seefeld, Federal Republic of Germany). When both clinical and radiographic treatment had been completed successfully, the final prosthetic treatment was carried out.

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%.

Ingle and Beveridge (1) have shown that the most frequent cause of failure after root canal treatment is inadequate obturation of the root canal system. One of the materials currently used for root canal obturation is gutta-percha, which has been used for over 100 years. For almost I0 years, experiments with a wide range of equipment have been undertaken with the obturation material mentioned above. In recent years, thermoplastic condensation techniques have been investigated in vivo as well as in vitro. Investigations have dealt with the apical seal (2-5), the homogeneity of filling materials (6), and the detected temperature during the obturation of root canals (7-10). These results have been compared with those of the lateral condensation obturation technique. However, there are few reports about clinical, practical experience with patients (11, 12). The purpose of this article is to report an evaluation of clinical experiences by the Obtura thermoplasticized gutta-percha obturation technique. M A T E R I A L S AND M E T H O D S The root canal treatments were performed in the Department of Conservative Dentistry and Periodontics, School of Dental Medicine, University of Bonn, Federal Republic of Germany. An X-ray of the teeth to be treated was taken and root canal access was attained with the use of rubber dam for isolation purposes. The root canals were irrigated with a 2% sodium hypochlorite solution by using an Endosonic unit (DeTrey/Dentsply) with a #15 stainless steel ultrasonic file. As soon as the root canal was dried with sterile paper points, an electronic measurement was taken to determine the working length (Exact-

RESULTS Forty-one teeth with a total of 71 root canals were treated with this method. The success rate was 93.75% (16 teeth) in cases of pulpitis and 92.38% (13 teeth) in cases of pulp necrosis, chronic periapical periodontitis, and suppurative apical periodontitis. Also included were cases of incompletely

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F~G 1. A, A preoperative radiograph of tooth 18 with an incomplete root canal filling. B, An immediate post filling radiograph. C, A 6month recall radiograph.

FCG2. A, A preoperative radiograph of tooth 3 showing a root filling with silver cones. B, An immediate radiograph of root canal filling demonstrating four separate canals. C, A 12-month recall radiograph.

obturated root canals with the presence of an apical lesion. These retreatment cases made up 29.26% (12 teeth) of all treated cases and had a similar success rate.

case of the destruction of the cementodentinaljunction during canal preparation, the apical area can be treated with calcium hydroxide (14) or packed with clean dentin chips. Some investigations have shown (11) that if gutta-percha is extruded beyond the apical foramen the periradicular tissue tolerates the gutta-percha and root canal sealer quite well, provided the canal-system has been correctly cleaned and sealed. In only three of our clinical cases was the gutta-percha extruded beyond the apical foramen. However, another investigation (15) has shown that the extrusion of the filling material into the apical tissues can

DISCUSSION The number of techniques for root canal filling has increased in recent years. It is important when using the method mentioned above to ensure that an apical barrier is present to control the application of gutta-percha (13). However, in the

Vol. 17, No. 8, August 1991

produce an acute inflammation followed by a chronic foreign body reaction. The heat generation during obturation with thermoplasticized gutta-percha has been examined in vitro and in vivo (16-18). The first studies were done in 1977 by Yee et al. (19), and similar studies since that time have shown that the temperature is well tolerated by the tissues. Nevertheless, other studies have shown an inflammatory reaction in the periapical area (18, 20) which decreases after a short observation period. Before working with the Obtura, the temperature of the gutta-percha extruded from the applicator tips was measured. The average temperature was 66.83~ with a range from 63.62 to 70.05~ According to the manufacturer, the applicator tips should be placed 3.0 to 5.0 mm from the apical matrix. My experiences show that this distance can be greater. The thermoplasticized gutta-percha injection obturation technique under radiographic and clinical examination has produced good results which do not differ from those of other root canal obturation techniques (Figs. 1 and 2). The correct use of information given in the technical manual for the "Obtura, Heated Gutta-Percha Delivery System" and practicing on a large number of extracted teeth will facilitate the creation of a good root canal obturation. Its use in anterior teeth is always possible and, if the operator has had the necessary experience, it can also be used in posterior teeth. The time saved during the obturation procedure is considerable, but one should never forget that materials and a special system are necessary.

I thank Mrs. Y. Roche-Harth for her help in reviewing the manuscript. Special thanks to Dipl. Phys. M. Gr0ner for his technical assistance with the temperature analysis. Dr. Sobarzo-Navarro is an assistant professor, Department of Conservative Dentistry and Periodontics, Dental School, University of Bonn, Federal Republic of Germany. Address requests for reprints to Dr. Victor Sobarzo-Navarro, Department of Conservative Dentistry and Periodontics, Dental School, University of Bonn, Federal Republic of Germany.

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