Quantitative and qualitative assessment of the wear pattern of two attachment systems of dissimilar materials for mandibular implant-retained overdentures: an in-vitro study

Abstract

Background: Attachment material is one of the contributing factors to the degree of wear of the attachment components in mandibular implant-retained overdentures. The purpose of this in vitro study was to compare the wear behavior of 2 different attachment systems of dissimilar materials in mandibular implant-retained overdentures by qualitative and quantitative methods.

Methods: Two attachment systems of different materials were utilized (n = 16); Titach (Dental Evolutions Inc, Beverly Hills, CA, USA) with a titanium-to-titanium interface and Locator R-Tx (Zest Anchors Inc, Escondido, CA, USA) with a titanium-to-nylon interface. One thousand cycles of overdenture insertion and removal simulating 1-year clinical use were performed. All matrices were removed from the overdentures and all patrices were unscrewed from the implants for wear assessment quantitively using a stereomicroscope and qualitatively using a scanning electron microscope. Data were analyzed by using an independent sample t test.

Results: After cyclic loading, stereomicroscopic findings showed that the Titach group had statistically significant higher wear value than the Locator R-Tx group (p < 0.001). Moreover, scanning electron microscopy images showed noticeable abrasion in Titach patrix at the area of highest convexity. However, the Locator R-Tx matrix displayed an apparent tear of rubber inserts.

Conclusions: Titach attachment with the titanium-to-titanium interface revealed more wear than Locator R-Tx attachment with the titanium-to-nylon interface. Thus, the type of attachment material influences the degree of wear of the attachment components.

Keywords: Attachment wear; Implant-assisted overdenture; Locator R-Tx attachment; Titach attachment; Titanium-to-nylon interface; Titanium-to-titanium interface.

Fig. 1

a Titach attachments screwed to the implants. b Implant-retained overdenture after pick-up of Titach's caps. c Locator R-Tx attachments screwed to the implants. d Implant-retained overdenture after pick-up of locator R-Tx attachment with clear nylon insert

Fig. 2

a T-shaped acrylic resin plate attached to the occlusal surfaces of the acrylic resin teeth at the incisal and first molar regions of overdentures by using autopolymerizing resin. b The center of the T-shaped plate with the overdenture attached to the upper member of the cyclic loading machine

Fig. 3

Stereomicroscopy images (original magnification × 25). A software program (Toup view, version 3.7) was used to measure the inner circumference of the attachment matrix and outer circumference of the attachment patrix. a Titach matrix. b Locator R-Tx matrix. c Titach patrix. d Locator R-Tx patrix

Fig. 4

Scanning electron microscope images before cyclic loading (original magnifications × 16), a Titach patrix. b Titach matrix, c Locator R-Tx patrix, d Locator R-Tx matrix

Fig. 5

Scanning electron microscope images of Titach attachment after cyclic loading. A Titach patrix at × 16 magnification revealing an obvious band of wear and abrasion across the height of contour. B Higher magnification (× 100) showing severe wear with metal sloughing. C Titach matrix showing a noticeable wear along the inner circumference. D Higher magnification (× 75) showing severe wear with metal sloughing

Fig. 6

Scanning electron microscope images of the inner surface of the Titach matrix (original magnification × 75, × 150, × 350). a Titach matrix before cyclic loading showing regular manufacturing lines. b, c Titach matrix after cyclic loading revealing accumulation of metallic powder

Fig. 7

Scanning electron microscope images of Locator R-Tx patrix after cyclic loading showing accumulation of nylon remnants along the narrower coronal area, A × 16 magnification, B × 100 magnification

Fig. 8

Scanning electron microscope images of the Locator R-Tx matrix after cyclic loading presenting a noticeable tear and deformation along inner circumference, A × 16 magnification, B × 75 magnification, C × 150 magnification