Drying and rewetting anterior crown fragments prior to bonding

Fractured anterior teeth can be restored by adhesive bonding of the fragmen t to the remaining tooth structure. This in vitro study describes the effec t on fracture strength of fragments dried and rewetted for various periods of time prior to bonding. Seventy central incisors from sheep were fracture d. The resulting incisal crown fragments were then stored in air at room te mperature at ambient humidity (70+/-16%) for 5 s, 30 min, 1 h, 3 h, 6 h, 12 h, or 24 h. The apical parts of the fractured teeth were stored in water. After storage in air each fragment was then bonded to the matching apical t ooth structure with a bonding agent and a low-viscosity composite resin. Af ter water storage for 2 days, mean fracture strength was measured. Another group of teeth comprising 40 sheep central incisors was fractured and die f ragments were stored in air at room temperature for 24 h as above. The frag ments were then immersed in water for 10 min, 1 h, 1 day, or 7 days, prior to bonding and measurement as described above. Statistical analysis reveale d that the fracture strength of the fragment-bonded teeth was unaffected by air storage of the fragment for up to 1 h prior to bonding, after which ad ditional drying resulted in decreased fracture strength. Fragments dried fo r 24 h in air and rewetted by immersion in water for at least 1 day were fr agment-bonded without loss of fracture strength.