• Oregon Health Sciences University School of Dentistry, Portland, OR.

The purpose of this in vivo study was to evaluate root-ends for cracks after root resection and again after ultrasonic root-end preparation in patients undergoing endodontic surgery. Endodontic surgery was performed on 25 roots from 20 patients. In vivo vinyl polysiloxane impressions were made after root resection and again after ultrasonic root-end preparations. Epoxy resin casts were made from the impressions and scanning electron micrographic examination of the root-end replicas was performed. There was no evidence of cracks after root resection. One incomplete canal crack was evident after ultrasonic root-end preparation.