Apical root canal cleaning after preparation with endodontic instruments: a randomized trial in vivo analysis

Abstract

Objectives: This study aimed to evaluate vital pulp tissue removal from different endodontic instrumentation systems from root canal apical third in vivo.

Materials and methods: Thirty mandibular molars were selected and randomly divided into 2 test groups and one control group. Inclusion criteria were a positive response to cold sensibility test, curvature angle between 10 and 20 degrees, and curvature radius lower than 10 mm. Root canals prepared with Hero 642 system (size 45/0.02) (n = 10) and Reciproc R40 (size 40/0.06) (n = 10) and control (n = 10) without instrumentation. Canals were irrigated only with saline solution during root canal preparation. The apical third was evaluated considering the touched/untouched perimeter and area to evaluate the efficacy of root canal wall debridement. Statistical analysis used t-test for comparisons.

Results: Untouched root canal at cross-section perimeter, the Hero 642 system showed 41.44% ± 5.62% and Reciproc R40 58.67% ± 12.39% without contact with instruments. Regarding the untouched area, Hero 642 system showed 22.78% ± 6.42% and Reciproc R40 34.35% ± 8.52%. Neither instrument achieved complete cross-sectional root canal debridement. Hero 642 system rotary taper 0.02 instruments achieved significant greater wall contact perimeter and area compared to reciprocate the Reciproc R40 taper 0.06 instrument.

Conclusions: Hero 642 achieved higher wall contact perimeter and area but, regardless of instrument size and taper, vital pulp during in vivo instrumentation is not entirely removed.

Keywords: Debridement; Dental instruments; Endodontics.

Figure 1. Consolidated Standards of Reporting Trials (CONSORT) 2010 flow diagram.

Figure 2. Representative diagrams used for curvature assessment previously to the operative procedures for distal roots included in the analysis. (A) Periapical radiograph used to curvature angle determination and (B) curvature radius determination [12].

Figure 3. Representative image (×50) (hematoxylin and eosin) of root canal cross-sectional perimeter used as a reference to evaluate surface considered as touched by instrumentation (arrows). The untouched area in the right shows the structure of normal predentin that was not removed by the action of the instruments, which was a frequent observation, especially in isthmus areas of oval root canal sections.

Figure 4. Histological images used for the assessment of perimeter and area. (A) Representative images (×50) (hematoxylin and eosin) with touched perimeter traced in yellow used to calculate touched/untouched perimeter ratio. (B) Representative images (×50) with total area traced in yellow used to calculate percentage area occupied by the instrument (blue circle).

Figure 5. Box-plot representation of (A) percentual perimeter not touched by instrumentation and (B) areas not occupied by the instrument.

Figure 6. Representative images of the control group (hematoxylin and eosin) without any instrumentation procedure. Arrows are indicating (A) pulp tissue (×50), (B) predentin layer (×100), (C) odontoblast layer (×200), and (D) showing dentin tubules (×400).