Extrusion-mixing compared with hand-mixing of polyether impression materials?
The hypotheses tested were two-fold (a) whether altering the base:catalyst ratio influences working time, elastic recovery and strain in compression properties of a hand-mixed polyether impression material and (b) whether an extrusion-mixed polyether impression material would have a significant advantage over a hand-mixed polyether impression material mixed to the optimum base:catalyst ratio. The polyether was hand-mixed at the optimum (manufacturers recommended) base:catalyst ratios (7:1) and further groups were made by increasing or decreasing the catalyst length by 25%. Additionally specimens were also made from an extrusion-mixed polyether impression material and compared with the optimum hand-mixed base:catalyst ratio. A penetrometer assembly was used to measure the working time (n=5). Five cylindrical specimens for each hand-mixed and extrusion mixed group investigated were employed for elastic recovery and strain in compression testing. Hand-mixing polyether impression materials with 25% more catalyst than that recommended significantly decreased the working time while hand-mixing with 25% less catalyst than that recommended significantly increased the strain in compression. The extrusion-mixed polyether impression material provided similar working time, elastic recovery and strain in compression to the hand-mixed polyether mixed at the optimum base:catalyst ratio.
Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Dublin 2, Republic of Ireland.
Caroline
C
McMahon
Daniel
D
Kinsella
Garry J P
GJ
Fleming
D002384:Catalysis; D019245:Compressive Strength; D003760:Dental Impression Materials / Q000138:chemical synthesis* / Q000737:chemistry; D003799:Dental Stress Analysis; D004339:Drug Compounding / Q000379:methods; D004548:Elasticity; D004987:Ethers / Q000138:chemical synthesis* / Q000737:chemistry; D008422:Materials Testing; D013997:Time Factors
D003760:Dental Impression Materials; D004987:Ethers