Wear of double crown systems: electroplated vs. casted female part

Abstract

ObjectivesThe wear of telescopic crowns is a common problem often reducing the patient's satisfaction with the denture and resulting in a renewal of the denture. The study aims to compare the wear behavior of conical crowns using electroplated copings (group E) with standard telescopic crowns with cast female parts (group C). Material and Methods10 conical crowns were milled for each group of a cast gold alloy. The specimen of group E had a conicity of 2º. The cast secondary crowns of group C had a 0º design. The electroplated coping was established by direct electroforming. An apparatus accomplishing 10,000 wear cycles performed the wear test. The retentive forces and the correlating distance during insertion and separation were measured. The wear test was separated in a start phase, an initial wear phase and the long term wear period. The retention force value and the force-distance integral of the first 0.33 mm of each cycle were calculated. ResultsThe retentive forces were significantly higher for group E and the integrals were significantly lower for this group except the integral at cycle 10,000. The changes of retention force and integral did not differ significantly between both groups in all phases. The change of the integrals as well as the integral at the particular cycles showed higher interquartile distances for group C. ConclusionsWithin the limitations of this study the tested conical crowns showed clinically acceptable retentive properties. The values reached a range comparable to retentive elements tested in recent literature. The values of group C showed higher ranges. The force measured for group E was significantly higher than for group C but the integrals showed an opposite tendency. The results indicate that an exclusive analysis of the force is not sufficient as the integral is not equivalent to the force although it describes the retentive property of the system in a better way than the force over a distance is described. Both systems seem to be suitable for clinical practice.

The Evaluation of Changes in Retention Force Values in Three-Element Telescopic Crown Systems using Simulated Load Cycles

“…This phenomenon explains the strain of the surface of the crown depends on the malleability of materials use. This phenomenon is characteristic especially for crowns made of gold alloys, where the observed initial decrease in the value of the retention force is momentarily stabilized until another decline in value and eventual complete loss of retention [1,31,32,35,36]. In this study the initial phase in all groups was in the range of 0-2500 cycles, followed by a period of relative stabilization of the value of the retention force in the range of 30000 cycles.…”

“…The most important factors include the tribochemical impact, abrasion, adhesion, and defects within the surface. These factors can occur separately or overlap, which can be related to the state of material and construction of the retention element [34][35][36].…”

“…Retention telescopic crowns are associated with the contact surface of the crown in the system and it depends on many factors, mainly the geometry of the crown and the type of material used to make the crowns [28][29][30][31][32][33][34][35][36][37][38]. The developments of materials and new technologies that can be used in dental prosthetics create the prospects of the appearance of new design concepts and materials in the near future.…”

Comparison of Retention Forces of Different Fabrication Methods of Co-Cr Crowns: Pre-sintered and Milled, Cast and Electroforming Secondary Crowns with Different Taper Angles

“…The electroformed double crown systems-as investigated in literature -showed different values of retention forces both higher [26] and lower [27] compared to non-electroplated crowns. There in, the electroplated secondary crowns on their cast primary crowns with a taper angle of 2° showed lower retention force values than the cast secondary gold crowns on their cast primary crowns.…”

“…Their system showed decreasing retention force values with an increased taper angle from 2° to 4°, up to 6° [25]. However, the retention force values achieved with electroplated secondary crowns were still sufficient and reproducible [20,26]. Additional parameters such as the viscosity of the used saliva, the chamfer design and details during the manufacturing process of electroplating influences the retention force [6,19,20].…”