TEMPERATURE AND HUMIDITY EFFECTS ON BOND STRENGTH OF A DENTINAL ADHESIVE

Dentin specimens from 46 extracted human molar teeth were used in a ma tched-pair design examining the factors of temperature/humidity on she ar bond strength of a dentinal adhesive to dentin. For one tooth-half, all procedures using restorative materials were accomplished in a con trolled temperature and humidity chamber (humidity 95.0 +/- 2.0%, temp erature 37.0 +/- 0.3 degrees C). For the other matched tooth-half all procedures were performed at ambient room conditions (humidity 52%, te mperature 23.3 degrees C/74 degrees F). Oil-free air and water were us ed in all restorative procedures. Application of Scotchbond Multi-Purp ose Adhesive System was followed by placement of Z100 Restorative Resi n, and thermocycling 1000 cycles from 5 to 55 degrees C. Each matched specimen was tested 24 hours later in an Instron Testing Machine. A pa ired t-test was performed for comparison of bond strength set values, since they were obtained from matching halves of the same teeth. Paire d t-test comparison showed that the average humidity/temperature chamb er mean of 7.14 +/- 3.12 MPa was significantly less than the ambient c onditions mean of 14.29 +/- 5.07 (P = 0.0000). Bond strength testing u nder simulated oral conditions may produce significantly different fin dings than customary bench-top laboratory experiments.