[The preparation of retrocavities in apicoectomies]

The purpose of this in vitro and in vivo study was to compare the quality of retrograde cavities and retrofilling using various retrograde techniques (microhead, ultrasonic). The quality was evaluated on the basis of dye penetration, macroscopic control, and both light microscopic and scanning electron microscopic examination. A total of 40 extracted teeth with a single canal were analyzed. The clinical result was evaluated in 25 patients with root-filled teeth and the indication of apicoectomy. Statistical analysis indicated that the seal was significantly better with ultrasonically prepared cavities than with microhead preparation. Retrofillings prepared ultrasonically also showed significantly fewer peripheral fissures. The scanning electron microscopic examination, however, demonstrated peripheral fissures in all filled teeth. Furthermore, the cavities prepared ultrasonically had a smoother surface and a lower smear layer. This preparation produced a more pleasing final result. The advantages of better accessibility during the preparation, namely, more precise preparation of the retrofilling and only minor substance loss were confirmed clinically. Using the ultrasonic equipment, absolutely sterile working conditions are present.