A study was conducted to compare the retentive properties of the obturator-reinforced composite resin dowel and core systems with and without corrugated dentin surfaces in the dowel channels. A commercially available tap with a diameter of about 1.4 mm and a thread groove depth of 100 micron was used to accomplish this dentin roughening. To compare whether methods of placement affect the retentive capacities of this dowel and core system, a Lentulo spiral, Jiffy tube, and Centrix C-R syringe were used to insert the resin mixes into the corrugated channels. The following conclusions can be drawn. By corrugating or roughening the dentin surface of the prepared channel, the retentive properties of this dowel and core system are significantly increased. In this system using minimal amounts of composite resin, the three methods of placement exhibited no significant difference in retention. The retentive failure seemed to occur at the resin-tooth interface. Increasing the degree of corrugation (deeper grooves) increased the retention, but caution must be exercised to prevent weakening the tooth.
Crowns Dental Instruments