Purpose: to evaluate the effects of orifice plugs using IRM or dentin bonding/composite resin on coronal leakage in vivo where the root canals were exposed to oral environment. The coronal leakage was assessed by the occurrence and severity of periapical inflammation
-A total of 61 premolar roots in three beagle dogs were used for this study. The dogs received a local anesthetic (bupivacaine 0.5 ml/quadrant) as regional nerve block anesthesia
-Root canal instrumentations were performed with ProFile rotary files and a #40 K file to working length. 1.25% sodium hypochlorite (NaOCl) was used for irrigation
-Each root canal was obturated with gutta percha and sealer except one group that received gutta-percha but not sealer
-Then the roots were divided into two groups. Group with orifice plugs (a total of 43 roots), Another group, a total of 18 roots (G + S), received no orifice plugs.
-Group with orifice plug : coronal 2 mm of filling material were removed and filled with IRM (G + S + IRM, n = 13) or composite resin (G + S + C, n = 18) and (G + C , n =12 ) Ø The pulp chamber was kept open to the oral environment for 8 months
-After 8 months, the dogs were killed and the upper and lower jaws were dissected
– The periapical regions of the roots were then examined under a light microscope at ×10 magnification.
-Periapical inflammation was rated as none: no inflammation with normal appearance of the root surface and surrounding tissue ,mild: with infiltrate localized to the periodontal ligament space without evidence of bone and root resorption , severe: numerous inflammatory cells surrounded the periapical area with bone/root resorption ,
•Most highlighted Results:
•During the 8 months, no periapical radiolucency was observed
•The group without plugs (G + S) showed an inflammation rate of 89%. Of those, severe inflammation was found in more than 55% of the roots. In the group with plugs, the inflammation rate was reduced to 38% (G + S + IRM), 39% (G + S + C), and 58% (G + C).
•The differences in the inflammation rate between the group without plugs and those with plug were statistically significant
•Clinical significance :
•Placement of orifice plug after root canal filling is important in order to prevent coronal leakage