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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 12  »  Quality of preparation of oval distal root canals in mandibular molars using nickel-titanium instruments
Quality of preparation of oval distal root canals in mandibular molars using nickel-titanium instruments
Assessment of preparation.



After preparation, the cross-sections of the distal root canals were photographed again. The divergence of pre- and postoperative root canal diameter was evaluated by superimposing pre- and postoperative canal outlines.
Following preparation, the cross-sections were removed from the mould and the three root segments were freed from the resin. From the mesial direction, two grooves were cut into the root and a v-shaped segment of the root could be removed so that the buccal and lingual extensions could be examined under the SEM (Fig. 1 a, b).The roots were coded and mixed so that the type of instrument used for preparation could not be identified during SEM investigation.
Separate evaluations were undertaken for debris and smear layerwitha5-score system. For each score system, the same set of reference photographs were used as in previous investigations (Hulsmann et al.1997, 2001, Versumer et al. 2002). Cleanliness was evaluated only in the buccal and lingual extensions of the canals. Debris was defined as dentine chips, pulp remnants and particles loosely attached to the root canal wall.
  • Score 1: Clean root canal wall, only few small debris particles.
  • Score 2: Few small isles of debris.
  • Score 3: Many accumulations of debris covering less than 50% of the root canal wall.
  • Score 4: More than 50% of the root canal wall covered by debris.
  • Score 5: Complete or nearly complete root canal wall covered by debris
Scoring of debris was performed using 200x magnification.
Smear layer was defined as proposed by the ‘American Association of Endodontists’ glossary ‘Contemporary Terminology for Endodontics’ (1994): a surface film of debris retained on dentine or other surfaces after instrumentation with either rotary instruments or endodontic files, consists of dentine particles, remnants of vital or necrotic pulp tissue, bacterial components and retained irrigant.
  • Score1: No smear layer, dentinal tubules open.
  • Score 2: Small amount of smear layer, some dentinal tubules open.
  • Score 3: Homogeneous smear layer covering the root canal wall, only few dentinal tubules open.
  • Score 4: Complete root canal wall covered by homogeneous smear layer, no open dentinal tubules.
  • Score 5: Heavy, inhomogeneous smear layer covering the complete root canal wall.
Smear layer was scored under 1000x magnification.

After the central beam of the SEM had been directed to the centre of the object by the SEM operator (F.S.) under 10x magnification, the magnification was increased to 200 and 1000x, respectively, and the canal wall region appearing on the screen was scored. The scoring procedure was performed by a second operator (M.H.) who could not identify the coded specimens. This operator had been trained in the scoring procedure, resulting in a sufficient intraobserver reproducibility (Hulsmann et al.1997).

Figure 1. (a) Specimen prepared for SEM investigation. A segment was removed from the mesial root canal wall allowing investigation of the buccal and lingual recesses.
(b) View into a buccal recesses under the SEM (magnification: 33x).

A segment was removed from the mesial root canal wall allowing investigation of the buccal and lingual recesses

Statistical analysis.
For comparison of the cross-sections, root canal cleanliness and working time, the Kruskal-Wallis test (P < 0.05) was used.