posterior keyway, which unites the fixed segments. Pin placement must not jeopardize the dental pulp. Etched-metal retainers with nonrigid connectors bonded to enamel have been clinically successful.4 Extrapolation of this technique provides a safer, more conservative, third option: luting the cast attachment to the anterior bridge with a resin adhesive. A casting with adjacent keys and lingual wings was made. After sandblasting of all opposing surfaces, the casting was luted to the anterior segment with Panavia (Kuraray Co. Ltd., Osaka, Japan) resin adhesive (Fig. 1).5* 6 On permanent cementation of the anterior bridge, the posterior key formed a nonrigid connector with the new keyway in the mesial surface of the first premolar (Fig. 2). The anterior lingual wing of the conversion attachment provided additional surface area for bonding. The posterior wing added stability to the nonrigid connector. The segments were reunited in a conservative fashion. To date (one year after placement) there has been no loosening of either segment from the abutments or unseating of the key from the keyway.
of the dowel
REFERENCES 1. Standlee JP, Caputo AA. Load transfer by fixed partial dentures with three abutments. Quint Int 1988;19:403-10. 2. Weiss AB. The bolt inlay: a new method of repairing and modifying cemented fixed prostheses. J PROSTHET DENT 1970;3:296-314. 3. Miller TH, Thayer KE. Intraoral repair of fixed partial dentures. J PROSTHET
4. Crispin BJ. Success of etched-metal bonded retainers with nonrigid connectors: a clinical study. J PROSTHET DENT 1989;62:269-72. 5. El-Sherif MH, El-Messery A, Halhoul MN. The effects of alloy surface treatments and resins on the retention of resin-bonded retainers. J PROSTHET
6. Garcia-Godoy F, Kaiser DA, Malone WFP, Hubbard G. Shear bond strength of two resin adhesives for acid-etched metal prostheses. J PROSTHET
Reprint requests to: DR. DAVID C. APPLEBY TEMPLE UNIVERSITY SCHOOL 3223 N. BROAD STREET PHILADELPHIA. PA 19140
Gary J. Kaplowitz, DDS, MA, MEd* U. S. Coast Guard Support Center, Seattle, Wash. Removal of gutta-percha to make room for a dowel space should involve no reduction of the walls of the root canal space, to minimize the threat of perforation. This can be safely accomplished by the application of a gutta-percha softening agent and a modified rotary instrument. An obturated canal is selected to receive the post. The orifice is cleared and the gutta-percha is exposed. A drop of rectified turpentine oil (Lorann Oils, Lansing, Mich.) is applied to the gutta-perchale and allowed to soften the superficial 3 to 4 mm over a l- to 2-minute period. A Gates-Glidden bur (Union Broach Co., Inc., Long Island City, N. Y.) smaller than the diameter of the obturated canal space is selected and the side-cutting instrument flutes near the tip are dulled with a file or abrasive disk. This will help to confine the bur to the gutta-percha mass and prevent the bur from creating a path outside the walls of the root canal space. The softened gutta-percha mass is removed from the root The views expressed herein are those of the author and are not to be construed as official or as reflecting the views of the Commandant, the U. S. Coast Guard, or the Department of Health and Human Services. VDR, Chief, General Dental Unit.
canal spaceto the depth desired with minimal threat of perforation. After the gutta percha has been removed, larger diameter Gates-Glidden bum or other side cutting instrument, such as Peeso reamers (Union Broach Co., Inc.), can be usedto enlargeand shapethe root canal space to the desired extent and form to accommodatethe post. The dowel spaceis flushedwith alcoholto remove traces of rectified turpentine oil. A direct or indirect technique can then be used to fabricate the dowel. REFERENCES 1. Kaplowitz G. Evaluation of gutta-percha solvents. J Endodont 1990;9:539-40. 2. Kaplowitz GJ. Evaluation of the ability of essential oils to dissolve gutta-percha. J Endodont 1991;17:448-9. 3. Wourms DJ, Campbell AD, Hicks ML, Pelleu GB Jr. Alternative solventstochloroformforgutta-percharemoval. JEndodont1990;16:224-6. Reprint requests to: CDR. GARY J. KAPLOWITZ CHIEF, GENERAL DENTAL UNIT U. S. COAST GUARD SUPPORT CENTER 1519 ALASKAN WAY SOUTH SFXI-TLE, WA 98134-1192