[The effect of coronal preflaring on the working length measurement of root canals in molars].
OBJECTIVE
To study the influence of coronal preflaring of root canal on the working length measurement in molars.


METHODS
48 molars from 47 adult patients with pulpitis were divided into two groups randomly. 74 root canals of 24 molars were examined in Group 1. After preparing an access cavity, the root canal orifices were located. A 15# K-type file was inserted into root canal to detect resistance at the apical region. 75 root canals of 24 molars were examined in Group 2. Before testing the apical resistance,a size 25# and 20# ProFile.06 taper NiTi rotary instrument was used to enlarge the canal orifice and flare the coronal portion of the root canal. After placing 15# K-type files, a radiograph was taken with the bisecting-angle technique. The distance between the tip of the file and the radiographic apex was measured on the radiographs. Statistical analysis of univariate and multiple logistic regression were carried out for analysis.


RESULTS
There was a significant difference between the two groups (P<0.05), there were more accurate measurements in Group 2 than in Group 1. No statistical correlation was found between X-ray measurements and age, sex and the position of molars,while there was significant correlation between maxillary molars and mandibular molars (P<0.05).


CONCLUSIONS
Preflaring the coronal portion of the root canals could significantly increase the accurate measurements of the working length of root canals in molars.
Department of Oral Medicine, College of Stomatology, Shandong University, Jinan 250012, Shandong Province, China. wangqing@sdu.edu.cn
Qing
Q
Wang
Shi-Jiang
SJ
Xiong
Hui-Qin
HQ
Dou
Rong-E
RE
Zhou
D000328:Adult; D000368:Aged; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008963:Molar / Q000033:anatomy & histology; D011671:Pulpitis / Q000628:therapy; D018915:Root Canal Preparation