Working length determination in palatal roots of maxillary molars

By Kim-Park M, Baughan L, Hartwell G.

Date: 01/2003
Journal: JOE


To determine if the presence of a buccal curvature in palatal roots of maxillary molars affected the ability of a clinician to accurately determine working length.

N=  27 extracted max molars , Excluded: teeth with apical root resorption or if apical foramen was not patent.


•radiographs obtained from a MD direction using parallel technique and conventional film.

•based on RGs, teeth were then sorted by palatal curvatures into J- type and C-type. and the angle of the palatal root curvature was determined using schneider’s method.

•A straight line access was prepared and a #20 NiTi file was placed into the palatal canal until the tip was visible at the apical foramen.

•Each tooth was placed on a sensor in a BL direction next to the niti file and a calibration wire. radiographs obtained.

•using the digital ruler.

•The actual  (file) and radiographic (tooth) lengths were measured. •Analysis of covariance was used to test for a relationship between the amount of curvature (in degrees) and the actual – radiographic lengths difference (in millimeters). Also, differences in types (J versus C) were compared.

Most highlighted Results: 

•Radiographic length appeared shorter on average than the actual length. •Canal curvatures larger than 25 degrees had differences greater than 0.5 mm between actual & radiographic lengths.

•There was no significant difference between the J- and C- types.

Clinical significance:

results show the limitation in using RGs for WL determination.

(combination of RGs and EAL should be used).