The Use of a Chloroform-softened Gutta-percha Master Cone and Its Effect on the Apical Seal

By Keane K, Harrington G.

Date: 09/1984
Journal: JOE


Purpose: to examine the effect on the apical seal of varying amounts of chloroform used in the formed cone gutta-percha filling technique.

N= 180 extracted single rooted teeth, max anteriors ,mand bicuspids ,cuspids. Exclusion: root curvature greater than 5° , apical foramen larger than #25, root fracture or bifurcation as observed by RG.


•Teeth were instrumented to 0.75 from apex using step-back technique, master file at least 3 sizes larger than 1st binding file (minimum of 40, maximum of 60). Coronal flaring done with gates, apical foramen enlarged to #25 for ink penetration .

•Group A: cone fitted 1-1.5 mm from WL was dipped 3 times for 1 sec in chloroform, 2 before sealer placement, 1 after then canal obturated with lateral condensation, closed with amalgam.

•Group B: 2 dips in chloroform

•Group C: 1 dip.

•Control 1: lateral condensation with sealer.

•Control 2: lateral condensation with no sealer.

•Control 3 :three Dips in chloroform with no sealer.

•All teeth closed with three coats of Copalite  and amalgam .Then all groups were placed in at 100% humidity at 37°C for 24 h to ensure set of the sealer, immersed in India ink for 24 hour, bench dried for 2 h, then stained on external surface removed with sandblasting, teeth decalcified and observed under dissecting microscope.

Most highlighted Results:

-Of the experimental groups, 1 chloroform dip had least median leakage while 3 dips had the most.

-The use of no sealer increases apical leakage dramatically, whether the master cone or formed cone technique is used. 

-No significant difference in leakage between lateral condensation and 1 dip of chloroform group.

Clinical significance: 

No clinical significance.

Leakage method isn’t reliable