The influence of master cone adaptation on the quality of the apical seal

By Allison D, Michelich R, Walton R.

Date: 07/1982
Journal: JOE


Purpose: to examine the relationship between the radiographic evidence used to determine master cone adaptation and the resultant quality of the apical seal , & to examine the relationship between the radiographic criteria and the visual and tactile criteria for assessing master cone adaptation.

N= 43 single rooted teeth. Inclusion : patent apex, curvature less than 20


•Straight line access,  WL within 1mm from apex. teeth prepared with either standardized or step-back technique. Then classified  according to the depth of spreader penetration. Spreader deep (0-1 mm from wl) or spreader short (>1 mm from wl).

•Adaptation of the master cones was assessed by visual, tactile, and radiographic means. All cones were fitted so that they were no more than 1.0 mm short of the prepared lengths.

•2 independent observers classified adaptation based on RG to adapted (0-0.5mm from wl. No lateral spaces), non-adapted (>1mm from WL, lateral spaces). Teeth were obturated with lateral condensation and ZOE. root covered with nail polish. Then kept in 100% humidity for 7-10 days. All specimens were then submerged in a solution of Ca, cross sectioned at 0.8 mm cross-sections . Autoradiographs for assessing microleakage were obtained,

Most highlighted Results:

-No correlation between microleakage and the presence of lateral space, apical space, Or a combination. üSpreader deep had significantly less microleakage than spreader short.

Clinical significance:

Taper is an important factor that reduced microleakage