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Hydration and dehydration periods of crown fragments prior to reattachment.

INTRODUCTION
Tooth fragment bonding is an excellent treatment option in dealing with traumatic injuries of the anterior teeth. Rewetting the tooth fragment has been shown to increase restoration durability. The present study examined the effect various dry and wet storage periods had on the reattached fragment's bond to the tooth.


MATERIALS AND METHODS
One hundred and eight human mandibular incisors were fractured and assigned to undergo a dehydration period of 30 minutes, six hours, 24 hours, or three days before the rewetting procedure. After fracturing the teeth and drying the fragments, each of the specimens was assigned to one of the three main groups (A, B, or C) intended to evaluate the effect of different rehydration periods. Groups A and B underwent a 30-minute and a 24-hour rewetting period, respectively. Group C served as a control (without a rewetting stage). Tooth fragments were then reattached and prepared for the strength test. Force was applied on the lingual side of the tooth at a 1 mm/min rate until failure.


RESULTS
The mean loads (N) required to fracture the restored teeth were as follows: 204.43 ± 33.48 N, 322.59 ± 34.62 N, and 253.25 ± 29.05 N for groups A, B, and C, respectively. Two-way analysis of variance (p<0.05) showed that rehydration and dehydration periods as well as their interaction caused significant differences in the strength of the final restoration. Multiple comparison tests showed that, in general, significant differences were not seen among different dehydration times prior to the rewetting stage (p>0.05), except in the case of the 30-minute dehydrated specimens (p<0.05).


CONCLUSION
Compared to a 30-minute period, a 24-hour rehydration of the tooth fragment before treatment seems to salvage enough moisture to result in an increase in reattachment strength.