A sonic instrument for retrograde preparation

Abstract

A surgical approach is required when a nonsurgical endodontic treatment is impossible or ineffective in resolving an endodontic problem (1). The successful outcome ofendodontic surgery requires a hermetic apical seal. Therefore, a retrograde filling is necessary when the apical sealing quality is doubtful (2). One of the prerequisites for a good filling is a good cavity preparation. A major difficulty in performing proper apical preparation is the limited working space. A conventional handpiece is often too bulky for preparing an apical cavity. A mini-head handpiece (DYNA DENT; Micro Motors, Santa Aria, CA) can be helpful, but it is usually still necessary to remove a certain amount of periapical bone to obtain a proper working position. In conventional root canal preparation, sonic as well as ultrasonic systems have been used as time-saving devices for root canal instrumentation. The Ultrasonic Retro-tips (Excellence in Endodontics, San Diego, CA) have recently been designed to be used in ultrasonic systems (ENAC; Osada Electric, Los Angeles, CA and Amadent, Cherry Hill, N J) and they have improved and simplified apical preparation and also minimized bone removal. Sonic handpieces are widely used in endodontic practice and therefore an attempt has been made to utilize a sonic instrument for apical cavity preparation. Tips were designed to be used in a MMI500 handpiece (Sonic Air MMI500 Endo System; Micro Mega, Woodside, NY) (Fig. 1). Extracted teeth were used to test the sonic instrument tips and to determine whether their energy level, which is lower than that of the ultrasonic instrument, was sufficient for the cavity preparation. It was possible to obtain a deep preparation which followed the original path of the apical root canal. These tips have also been tested clinically. It was found that FiG 1. Comparison of the sizes of the conventional handpiece, the mini-handpiece, and the surgical tip for the MM1500 Sonic Air Handpiece.