Laboratory investigation into optimal temperature for plaster of Paris application.

Objective: The present study aimed to determine the relationship between heat generated and time taken to reach maximum temperature when creating plaster of Paris casts, in relation to dipping water temperature and plaster slab thickness.

Methods: The study was conducted in a laboratory setting. A standard procedure for dipping, draining, layering and covering plaster slabs was developed. A standard temperature measurement and data-recording method was applied. Variables tested were dipping water temperature (25, 30, 40, 50 degrees C) and plaster slab thickness (10-ply and 15-ply).

Results: Mean maximum temperature varied between 31.9 and 41.7 degrees C, and was proportional to dipping water temperature and plaster slab thickness. Mean time to maximum temperature varied between 1216 and 728 s, and was inversely proportional to dipping water temperature and directly proportional to plaster slab thickness. All means were significantly different (P = 0.01).

Conclusion: Increasing dipping water temperature and number of layers of plaster when making plaster slabs significantly increases temperature of plaster setting. These data are important for an understanding of optimum conditions for safer cast application. The present study highlights the need for further research in this area.