Computed tomography evaluation of residual root thickness after pre-flaring using gates Glidden drills: The sequence effect.
OBJECTIVE
The aim of the present study is to evaluate the residual root thickness in mesiolingual (ML) canals of mandibular molars after pre-flaring using different sequences of Gates-Glidden (GG) drills.


METHODS
Computed tomography (CT) scans of the ML canals of 60 mandibular first molars were provided from areas within 1, 2, 3 and 4 mm of the furcation area and minimum initial root thickness (MIRT) of concave areas was measured at each level. The samples were divided into two groups (G1 and G2) which were prepared by the step-back and crown-down techniques, respectively. In both groups, anti-curvature filing was used. On secondary CT images of the samples in the same position, the minimum residual root thickness (MRRT) and the amount of removed dentin were analyzed by t-test and ANOVA.


RESULTS
There was no significant difference for MIRT between the two groups. The MRRT was greater in the G2 group in all the sections, with no significant difference between them. The average of MRRT was not <0.5 mm in any of the groups or sections.


CONCLUSIONS
Based on the results of this study when the appropriate root thickness is present initially, GG drills used in any sequence may be suitable, safe and cost effective for pre-flaring of mesial canals of mandibular first molars with preserving the root thickness of furcation areas.
Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran.
Nahid M
NM
Akhlaghi
Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran.
Amirali
A
Naghdi
Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran.
Laleh Mohammadian
LM
Bajgiran
Department of Endodontics, Dental Branch, Islamic Azad University, Tehran, Iran.
Elahe
E
Behrooz
Crown-down; Gates-Glidden; dentin removal; residual root thickness; step-back