Sr. No Temperature in degrees centigrade Duration in minutes Sample Size Morphologic changes Radiographic Changes
1 100 30 12 Pale to light yellow 
retained surface luster
No appreciable changes
2 300 30 12 Light gray with dark gray patches
Roots - Yellowish brown
Fissures between enamel and dentin
3 500 30 12 Enamel –Light  to Dark bluish gray Patches
Roots - Grayish brown
Loss of surface luster
Fractures between enamel/dentin and within dentin
4 700 30 12 Light bluish gray to Dark bluish gray
Disintegration into small fragments
Fractures between enamel/dentin and within dentin
5 1000 30 12 Neutral white with Light bluish gray
And  Light greenish gray patches
Large fractures spreading through dentine and crown crushing.
Table1: Morphologic and Radiographic changes observed in teeth exposed to hightemperatures for 30 minutes.