Purpose: To evaluate the effect of time and moisture on the setting, retention, and readaptation characteristics of MTA when used to repair furcation perforations.
N= 32 freshly extracted max and mand molars.
Materials and methods:
•The crowns of the extracted teeth were removed just above the floor of the pulp chamber, and the roots were removed below it, and the remaining section was mounted in an acrylic base.
•A perforation was made perpendicular to the furcation using a round burr #2, enlarged with GG #5.
•Gelfoam was used as a matrix material and freshly mixed MTA was placed in the perforation site.
•Teeth were divided into 4 groups equally:
•Group 1 : wet cotton pellet over the MTA for 24 hrs.
Group 2: wet cotton pellet over MTA for 72 hrs.
•Group 3 : dry cotton pellet over the MTA for 24 hrs.
Group 4: dry cotton pellet over MTA for 72 hrs.
•Pushout test: was made for all groups using an Instron force probe with vertical force on the MTA, and the maximum force was recorded in pounds of force, then the test was stopped after 0.2 mm displacement.
Most highlighted results:
•Group 1: Mean retention value of 2.2 lb.
Group 2: Mean retention value of 6.3 lb. ( Statistically significant p<0.05 ) •Group 3: Mean retention value of 2.6 lb.
Group 4: Mean retention value of 9.7 lb. ( Statistically significant p<0.05 ) •Resistance of displacement of the MTA was significantly greater at 72 hrs in both wet and dry conditions.
: It is proved that placement of a cotton pellet either wet or dry over the MTA for 72hr before placement of the final restoration will result in better adaptation.