Discussion - References.
The present study evaluated the removal of root canal filling materials with 0.04 ProFile system and whether the working length was reached. The fracture of two instruments in the cervical third was probably owing to errors in radicular access (insufficient opening) and the high frequency of use of the 0.04 ProFile instruments.
In the present study, the mean time required to remove the Thermafil plastic carriers was less than the half mean time reported in the study of Frajlich et al. (1998). The presence of a plastic carrier (group I) increased the average time needed to remove the filling material from the root canal (Bertrand et al. 1997, Ibarrola et al.1993,Wilcox1993). However, the Thermafil plastic carriers were removed totally.
According to Wilcox & Juhlin (1994), when solvents are used they form a thin film of filling material that is diffficult to detect and remove, which reduces the action of intracanal antibacterial medicaments. The proper adaptation of subsequent filling material on the root canal walls canal sobeimpaired. Thus, it is important to search for more efficient methods for the re-treatment of root canals.
The main disadvantage of this technique was the inability to adequately clean large root canals and canals that were not round. Because in most cases, incomplete removal of the gutta-percha and sealer was observed, the authors suggest that it was the result of anatomical features of the teeth used in this study. Also, owing to the fact that the ProFile system rotates 3608, we suggest the associated use of manual instruments such as hedstroem files (Weine,1998), to achieve complete removal of filling materials.
Aun CE, Santos M (1989) Quantity of apical extruded material and efficiency of five different methods of removing guttapercha and sealer from root canals - 'in vitro' evaluation. Revista Da Faculdade de Odontologia Da Zona Leste de SaoPaulo 1, 63-73.
Bertrand MF, Pellegrino JC, Rocca JP, Klinghofer A (1997) Removal of thermafil root canal filling material. Journal of Endodontics 23, 54-7.
Frajlich SR, Goldberg F, Massone EJ, Cantarini C, Artaza LP (1998) Comparative study of retreatment of thermafil and lateral condensation endodontic fillings. International Endodontic Journal 31, 354-7.
Friedman S, Stabholz A (1990) Endodontic retreatment - case selection and tecnique. Part 3. Retreatment techniques. Journal of Endodontics 16, 543-9.
Goerig A, Michelich RJ, Schultz HH (1982) Instrumentation of root canals in molar using the step-down technique. Journal of Endodontics 8, 550-4.
Ibarrola JL, Knowles KI, Ludlow MO(1993) Retrievability of thermafil plastic cores using organic solvents. Journal of Endodontics19, 417-21.
Imura N, Kato AS, Gata G-I, Uemura M, Toda T, Weine F (2000) A comparison of the relative efficacies of four hand and rotary instrumentation techniques during endodontic retreatment. International Endodontic Journal 33, 361-6.
Weine FS (1998) Tratamento Endodontico, 5th edn. Sao Paulo, SP, Brazil: Santos.
Wilcox LR (1993) Thermafil retreatment with and without chloroform solvent. Journal of Endodontics19, 563-6.
Wilcox LR, Juhlin JJ (1994) Endodontic retreatment of thermafil versus laterally condensed gutta-percha. Journal of Endodontics 20, 115-7.