Indonesia is a tropical climate country with wide range temperature. A lot of dental clinics do not used air conditioner equipment. The room temperature influences water temperature for mixing alginate impression materials. Objectives: The aim of this study was to investigate the functional relationship of room temperature and initial setting time of alginate impression materials. Methods: The New Kromopan® alginates (normal and fast sets) were used. The initial setting time was tested in laboratory room at temperatures : 23 (control), 24, 25, 26, 27, 28, 29, and 30 degrees Celcius ( n=5). The initial setting time was tested based on ANSI/ADA Specification no.18 (ISO 1563). The data were analyzed by linear regression. Results: The results showed that the increasing room temperatures caused the shorter alginate setting time.
Mean and S.D. initial setting time of alginates (second)
| Room Temperature ( oC) | Normal set alginate | Fast set alginate |
| 23 (control) | 149.60 + 0.55 | 122.00 ± 1.00 |
| 24 | 122.40 ± 0.55 | 97.60 ± 0.89 |
| 25 | 112.20 ± 0.45 | 95.00 ± 0.71 |
| 26 | 106.20 ± 0.84 | 90.60 ± 1.14 |
| 27 | 102.20 ± 0.83 | 85.20 ± 1.09 |
| 28 | 99.60 ± 0.55 | 81.20 ± 0.84 |
| 29 | 98.40 ± 0.55 | 76.00 ± 1.41 |
| 30 | 97.20 ± 0.45 | 72.20 ± 0.84 |
| 31 | 94.60 ± 0.89 | 69.60 ± 0.55 |
The coefficient of determination of room temperature to initial setting time of alginate were R2=0.74 (normal set) and R2=0.88 (fast set). The regression equation for normal set was Y= 257.6 - 5.5 X (p<0.01) and fast set was Y= 237.7 – 5.6 X (p<0.01). Conclusion: The room temperature gave high contribution and became strength predictor for initial setting time of alginates.