Effect of Different Temporary Cements on Retention of Crowns Cemented on One Piece Abutments with Two Different Lengths

To ensure retrievability of cemented implant-retained restorations، use of provisional cements has been suggested as an alternative to that of definitive ones. Some cements are stronger than other ones. To maintain retrievability، selection of the provisional cement is important. The aim of this study was to compare the tensile strength of three different temporary cements in crowns cemented on one piece abutments with two lengths. Twenty DIO implant analogs were fixed in an acrylic block using a dental surveyor. Blocks were divided in to two groups of 10 abutments. In one group، solid abutments with 3. 5mm diameter and 5. 5mm height and in the other one، abutments with 3. 5mm diameter and 7 mm height were placed in each implant analogs and torque to 30 N. cm. After fabrication of crown for each abutment، provisional luting agents Temp bond، Dycal and Temp bond clear were used to cement the crowns to the respective abutments. All specimens were stored in 100% humidity environment for 48 hours at 37c prior to testing. Crowns were pulled from abutments with a universal testing machine at a cross head speed of 0. 5 cm/min and tensile strength was recorded in Newton. Data were analyzed using 2-way analysis of variance (ANOVA). Tensile strength was significantly higher for Dycal (138. 6) than for Temp bond clear (68. 3) and Temp bond (30. 3) (P<0. 001). Also for each type of cement، the mean tensile strength was significantly higher at 7×3. 5mm abutments compared with 5. 5×3. 5mm (P=0. 006). It is preferred to use Temp bond while we need retrievabibity of cement retained fixed implant restorations and Dycal while we need higher retention.