Abstract
The aim of this study was to evaluate the compressive resistance under oblique loads of abutments with two different diameters and transmucosal heights used for cement-retained implant-supported prostheses in Morse-taper implants. Forty Morse-taper implants were divided into four groups with different abutment sizes for cement-retained prostheses in order to perform the compressive test. The groups were divided by abutment diameter and transmucosal height as follows: Group 1: 4.5 x 2.5 mm; Group 2: 4.5 x 3.5 mm; Group 3: 3.3 x 2.5 mm; and Group 4: 3.3 x 3.5 mm. An oblique compressive loading test was performed on each sample located in a platform at 30° using a universal testing machine with a load cell of 1,000 kgf and 0.5 mm/min speed until achieving the deformation of abutment's neck. The compressive resistance and its mechanical behavior were recorded for each group and the data were analyzed using ANOVA, the Shapiro-Wilk and Scheffé tests. In addition, the detailed damage of all samples was recorded with a conventional camera linked to the endoscopic equipment. Significant differences were observed among the groups, except between Groups 2 and 3 (p>0.005). All the abutments showed permanent deformations in the upper region and at the transmucosal portion, but the threads of the screws were intact. Fractures were only identified in Groups 3 and 4. Stronger mechanical behavior and compressive resistance was observed in the abutments with 4.5 mm diameter and 2.5 mm transmucosal height.
Highlights
Despite the high success rate of current dental implant treatments, some mechanical complications may occur, such as abutment loss or implant/abutment fracture [1]
It was observed that a lower transmucosal height resulted in a greater magnitude of the peak load for each sample
Fractures were only observed in the coronal portion of the 3.3 mm diameter abutments
Summary
Despite the high success rate of current dental implant treatments, some mechanical complications may occur, such as abutment loss or implant/abutment fracture [1]. Within the current implant connections in the market, the Morse taper connections have shown the highest reliability when subjected to mechanical tests [1]. Several studies have been conducted on the stress concentration of different implant/abutment configurations [2,3,4], but the real clinical significance of these results requires its validation by mechanical tests [1]. The prosthetic treatment involving endosseous implants may include screw-retained or cement-retained restorations [5]. The screw-retained implant-supported prostheses were developed to maintain the retrievability and maintenance of the restorations [6]. The use of cement-retained restorations has increased significantly, mainly because of its esthetic features, passive fit and cost [7], as well as its more favorable stress distribution [4]
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