The Effect of Degree of Taper, Surface Roughness and Type of Cement on Retention of Cement-Retained Implant Supported Crowns

Abstract

Retention is a long-standing topic of research on fixed dental prosthodontics. The retention of implant supported prosthesis depends on several factors as abutment taper, surface area, abutment height, surface roughness and type of cement. The purpose of this study was to assess and compare the effect of degree of taper, surface roughness and type of provisional cement on retention of cement-retained implant supported prosthesis. 40 implant analogs attaching with their abutments were embeded in 40 acrylic resin blocks.The implant abutment in the study (n=40) were classified into two groups of 20 each according to type of Surface Roughness Group (І): 20 Smooth surface titanium abutments. Group (‖): 20 Sandblasted surface titanium abutments. Each group was subdivided into two sub-groups (n=10), according to Degree of Taper • Subgroup (A) (n=10): Titanium abutments with 8º of taper. • Subgroup (B) (n=10): Titanium abutments with 16º taper.

Each Sub-group was subdivided according to Type of Provisional Cementsused: (X) (n=5): Zinc oxide &eugenol cement (TempBond) used to cement metal copings to abutments. (Y) (n=5): Resin cement (DentoTemp) used to cement metal copings to abutments. 40 Nickel-Chromium metal copings were constructed. Then, each one was cemented to the implant abutments. Each sample was subjected to a pull-out test using computer controlled Universal Testing Machine (Instron, 3345, Instron Corp, Cnton, Mass) at cross head speed of 0.5 mm/min crosshead speed until failure occurred.Loads required to remove the copings were recorded using computer software and means values for each group determined. Data were collected and statistically analyzed using IBM® SPSS® (SPSS Inc., IBM Corporation, NY, U.S.A.) Statistics Version 23 for Windows. Results revealed thatdifferent Degree of Taper, Surface Roughness, and Type of Cements showed a significant difference on mean Retention Load (Newton) at P≤0.001. and, there was a significant effect of interaction between (Taper * Cements) on mean Retention Load (Newton) at P≤0.001. But, there was insignificant effect of interaction between (Surface * Taper), (Surface * Cements), (Surface * Taper * Cements) on mean Retention Load (Newton) at P=0.389, P=0.332 and P= 0.101 respectively. The lowest significant retentive strength was in Using Zinc Oxide &Eugenol (TempBond) with 16º Smooth subgroup (42.26±20.44N). But, the highest significant retentive strength was in Using Resin Cement (DentoTemp) with 8º Sandblasted subgroup (547.81±94.49 N)