Objective      To evaluate and compare the in vitro sealing ability of white Portland cement (WPC)

WPC+ Bi

2

O

3

(BO)

WPC+ ZrO

2

(ZO)

mineral trioxide aggregate (MTA) and gray Portland cement (GPC) as root filling materials.       Methods      One hundred and four premolars with single root canal were instrumented and set as retrograde filling modle. The teeth were randomly divided into 5 groups

WPC

WPC+BO

WPC+ZO

MTA and GPC

with 20 teeth in each g

roup

and 2 control groups (positive and negative control groups

n=2). The teeth were exposed to Indian ink. And the extent of dye penetration was measured with stereomicroscopy.       Results      The negative controls showed no dye penetration while dye penetration was seen in the entire root canal of positive controls. However

WPC

WPC+BO

WPC+ZO and MTA groups showed slight dye penetration

though there was no significant difference  in their extent of dye penetration(

P

0.05). More dye penetration was found in GPC group

statistically more than the other 4 groups (

P

0.01).       Conclusion      Sealing ability of WPC

WPC+BO

and WPC+ZO is the same as that of MTA when used as root filling materials. All of them are better than GPC. ZO and BO might be good alternatives as radiopacifying agents.