Sensitivity of catalyst/base ratio on curing of resin luting agents: polymerization exotherm analysis.
OBJECTIVE
Currently, the proposed test of the International Standardization Organization (ISO) for measuring working and setting times of resin luting agents is based on measurement of times to reach specified stages on the polymerization exotherm. The objective of this study was to use this test to investigate the influence of variations in the mass ratios of catalyst paste to base paste on the working and setting times of three dual-cured dental resin luting agents.


METHODS
The materials used were Dicor Light Activated Cement (Dentsply International Inc.), Palfique Inlay Resin Cement (Tokuyama Soda Co.), and Vivadent Dual Cement (Vivadent). Fifteen specimens of each material were tested for working time by spatulating mass ratios from 0.7 to 1.3 for 30s at 23 degrees C and recording the time from beginning of spatulation to the time at which a temperature increase occurs. Ten specimens of each material were tested for setting time by spatulating in a similar manner at 37 degrees C and recording the time at which the temperature reaches a maximum value.


RESULTS
The data were fitted to the relation, In t = In A + Bm, where t is the time in seconds, m is the mass ratio, and A and B are regression coefficients. The results suggest that working and setting times of the specimens were independent of variations in mass ratio. A comparison among the materials was made by using a multiple linear regression with the relation, In t = In C + Dm + E gamma + Fm gamma, where gamma is a dummy variable to help distinguish between materials, and C, D, E, and F are regression coefficients. The results suggest that differences in materials influence the working time but not the setting time.


CONCLUSIONS
These results infer that variations in mass ratio (+/- 20%) often observed in the clinical setting should not have a significant influence on the working and setting times of resin luting agents.
D000180:Acrylic Resins / Q000737:chemistry; D002384:Catalysis; D003188:Composite Resins / Q000737:chemistry*; D003738:Dental Cements / Q000737:chemistry*; D016014:Linear Models; D008422:Materials Testing; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
D000180:Acrylic Resins; D003188:Composite Resins; D003738:Dental Cements; C097101:Palfique Inlay Resin Cement; D011140:Polyurethanes; D019279:Resin Cements; C059495:dicor cement; C069103:Dual Cement