Discussion - References.
The use of radiographs during paediatric endodontic therapy should be considered carefully. The diagnostic value is often limited and exposure of children to X-rays should be limited. Alternatives such as tactile methods (Bagett et al. 1996), acoustic methods (Inoue & Skinner 1985) or electric methods (Czerw et al. 1995, Pratten & McDonald 1996, Vajrabhaya & Tepmongkol 1997, Dunlap et al. 1998, De Moor et al. 1999, Ibarrola et al. 1999, Weiger et al. 1999) have been suggested in the past. This method has also been proposed for primary teeth: an in-vitro study reported superior results of the root length determination by the Root ZX device compared to radiographs (Katz et al. 1996).
There are a number of factors that might affect electrical measurement of root canal length. One might be the presence of root resorption, which often occurs physiologically in primary teeth. It may, however, be pathologically present in both permanent and primary teeth. Radiographic assessment of small areas of resorption is difficult, particularly in cases where resorption occurs on buccal or lingual aspects of the root. This will often not be visible radiographically, resulting in an increased risk of overinstrumentation and/or overfilling. Overfilling of primary teeth beyond the apex is associated with a reduced clinical outcome, at least with fillings containing Eugenol (Holan & Fuks 1993). Although there are alternative materials that may be less critical for overfilling in primary teeth, there is no doubt that overinstrumentation of a primary tooth can damage the germ of a permanent tooth (Nowak 1999). For this reason incomplete instrumentation has been indicated in those teeth which are seen in radiographs to be close to a tooth bud (Garcia- Godoy 1987). On the other hand, underfilling is also a risk factor for clinical success (Holan & Fuks 1993).
HÃ¼lsmann & Pieper (1989) demonstrated that an apex locator gave incorrect results in teeth with open apices. However, these authors used a first-generation apex locator, whereas a third-generation Tri Auto ZX device, that is less susceptible when used in similar conditions, was used in the present study.
The results of our study demonstrate that interexaminer reproducibility of electrical determination of root canal length in vitro is high for primary teeth, both with and without initial root resorption. The accuracy of determination of the acceptable working length was also high compared with the radiographic results. The Tri Auto ZX device is calibrated by the manufacturer to measure the tooth length minus 0.5 mm. It has already been stated that the reliability of electrical root canal length determination is slightly higher than of radiographic assessment (Pratten & McDonald 1996). It should be noted that the radiographs used in our study were not taken in vivo and are probably of higher quality than those taken intraorally, which will include surrounding bone and potential loss of clarity through angulation.
Bagett FJ, Mackie IC, Worthington HV (1996) An investigation into the measurement of the working length of immature incisor teeth requiring endodontic treatment in children. British Dental Journal 181, 96-8.
Buchalla W, Attin T, Brucklmeier R, Hellwig E (1999) Computergestatzte Methode zur quantitativen Bestimmung der apikalen Undichtigkeit von Wurzelkanalfullungen. Deutsche Zahn?rztliche Zeitschrift 54, 244-8.
Coll JA, Sadrian R (1996) Predicting pulpectomy success and its relationship to exfoliation and succedaneous dentition. Pediatric Dentistry 18, 57-63.
Czerw RJ, Fulkerson MS, Donnelly JC, Walmann JO (1995) In vitro evaluation of the accuracy of several electronic apex locators. Journal of Endodontics 21, 572-6.
De Moor RJ, Hommez GM, Martens LC, De Boever JG (1999) Accuracy of four electronic apex locators: an in vitro evaluation. Endodontics and Dental Traumatology 15, 77-82.
Dunlap CA, Remeikis NA, Begole EA, Rauschenberger CR (1998) An in vivo evaluation of an electronic apex locator that uses the ratio method in vital and necrotic canals. Journal of Endodontics 24, 48-50.
Fuks AB, Eidelman E (1991) Pulp therapy in the primary dentition. Current Opinion in Dentistry 1, 556-63.
Garcia-Godoy F (1987) Evaluation of an iodoform paste in root canal therapy for infected primary teeth. ASDC Journal of Dentistry for Children 54, 30-4.
Holan G, Fuks AB (1993) A comparison of pulpectomies using ZOE and KRI paste in primary molars: a retrospective study. Pediatric Dentistry 15, 403-7.
H?lsmann M, Pieper K (1989) Use of an electronic apex locator in the treatment of teeth with incomplete root formation. Endodontics and Dental Traumatology 5, 238-41.
Ibarrola JL, Chapman BL, Howard JH, Knowles KI, Ludlow MO (1999) Effect of preflaring on Root ZX apex locators. Journal of Endodontics 25, 625-6.
Inoue N, Skinner DH (1985) A simple and accurate way to measuring root canal length. Journal of Endodontics 11, 421-7.
Katz A, Mass E, Kaufman AY (1996) Electronic apex locator: a useful tool for root canal treatment in the primary dentition. ASDC Journal of Dentistry for Children 63, 414-7.
Nowak AJ (1999) Pediatric Dentistry - the Handbook, 2nd edn. Chicago, IL, USA: American Academy of Pediatric Dentistry.
Pratten DH, McDonald NJ (1996) Comparison of radiographic and electronic working lengths. Journal of Endodontics 22, 173-6.
Vajrabhaya L, Tepmongkol P (1997) Accuracy of apex locator. Endodontics and Dental Traumatology 13, 180-2.
Weiger R, John C, Geigle H, Last C (1999) An in vitro comparison of two modern apex locators. Journal of Endodontics 25, 765-8.
Yacobi R, Kenny DJ, Judd PL, Johnston DH (1991) Evolving primary pulp therapy techniques. Journal of the American Dental Association 122, 83-5.