Evaluation of Root Canal Transportation Centering Ratio and Remaining Dentine Thickness in Curved Root Canals Prepared with WaveOne Gold in Combination with Different Glide Path Techniques

Abstract

The aim of this in vitro study was to investigate various glide path preparation instruments followed by root canal preparation with the reciprocating Primary WaveOne Gold instrument in curved mesial root canals of extracted human mandibular molars. Micro Computed Tomography (micro-CT) was used. Canal transportation, centering ability and effect on remaining dentine thickness were evaluated over the apical, midroot and coronal levels (3 mm, 5 mm and 7 mm from the root apex). In addition, preparation times for glide path preparation and final canal preparation with the Primary WaveOne Gold instrument were also recorded and compared. Sixty curved mesio-buccal root canals were randomly divided into four groups. These groups were Group 1: no further glide path preparation (n=15); Group 2: glide path enlarged with the use of pre-curved size 10,15 and 20 stainless steel K-files (n=15); Group 3: manual glide path enlargement with a size 10 K-file and further preparation with rotary PathFiles no.1-3 (n=15); and Group 4: manual glide path enlargement with a size 10 K-file and further preparation with the reciprocating WaveOne Gold Glider (n=15). Micro-CT was used to scan teeth before and after glide path preparation. The final canal preparation was done with the Primary WaveOne Gold instrument after which all 60 specimens were scanned again by means of micro-CT. The three-dimensional images obtained before instrumentation, after glide path preparation and again after final canal preparation with the Primary WaveOne Gold instrument were reconstructed and interpreted. Centering ratio values, canal transportation, remaining dentine thickness as well as glide path and final canal preparation times were recorded and compared between the four glide path groups with the use of a one-way analysis of variance (ANOVA) for parametric and Kruskal-Wallis H test for non-parametric comparisons. Statistical significance was set at p< 0.05. PathFiles performed most favourably when mean centering ratios were compared over all three levels from the root apex. However, no statistically significant difference in the mean centering ratios was found after glide path preparation when K-files, PathFiles and the WaveOne Gold Glider were compared. Mean combined transportation over the apical, midroot and coronal levels after glide path preparation was statistically significantly higher in the K-file preparation groups compared to the PathFile and WaveOne Gold Glider groups. There was no statistically significant difference in the mean combined centering ratios or transportation values of the various glide path groups in combination with the Primary WaveOne Gold instrument over the apical, midroot and coronal levels. Although not statistically significant, the highest mean transportation values were seen in the group where no glide path was prepared prior to final canal preparation with the Primary WaveOne Gold Instrument. All glide path groups performed similarly in evaluation of preservation of dentine when they were used in combination with the Primary WaveOne Gold instrument. Not having a prior glide path resulted in the most dentine thickness reduction after final canal instrumentation with the Primary WaveOne Gold instrument. Glide path preparation was statistically significantly fastest with the use of the WaveOne Gold Glider (p<0.0001). Having no prior glide path preparation resulted in statistically slower final canal preparation in combination with the Primary WaveOne Gold instrument compared to the other three glide path preparation groups (K-files, PathFiles and WaveOne Gold Glider) (p<0.0001).