الفهرس 
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Abstract
In this work, three different milled bar materials for implant-supported mandibular overdentures were compared in vitro for their mean retention values. Using a commercially available mould, a model of the canine and second premolar portions of the mouth was created, and four identical implants were implanted using a guide template. Spiral drills fitted to a parallometer were used to create niches in which implants may be put.
Self-curing acrylic resin was used to adhere the implants to the models to mimic osseointegration. It was coated with a 2mm-thick soft liner to mimic the texture of the oral mucosa. The implant was scanned on a desk top using multiunitabutments with digital scan bodies connected. The exocad programme received a comprehensive digital 3D picture file and electronically delivered the information. It was sent to the milling machine with the bar’s design and parameters for milling. Milled bars made of polyether ether ketone (PEEK), zircon, and titanium were the first three materials considered. Construction began on an overdenture of titanium framework and barthen rings on top of each other, which were then positioned on the geometric centre. After placing a triangle sprue wax rod with the apex between the two central regions and the base at retro-molar area, a sprue wax line extended vertically to split the triangular into two triangulars, then another sprue wax extended from retro-molar area to the centre of this line.
The retentive forces of the examined attachments were measured using the universal testing equipment.
The metal ring was subjected to a 50 mm/min tensile strain until the attachment broke apart. During mastication, the overdenture was moved away from the tissue at a faster rate because of this.
Conclusions
Due to the variety of interlocking mechanisms, the variety of study techniques, and the absence of established technical norms, it is hard to identify the optimal attachment materials. PEEK remains the most well studied attachment material in the literature, although titanium is currently the most often employed because of its anteriority. Two conclusions may be drawn from the research examined, in accordance with the study’s goals:
For starters, the retention forces provided by PEEK and ZIRCON are equivalent, but PEEK has a larger and more significant retention value, particularly after repeated insertion and removal of the prosthesis.
Second, cycling has a negligible effect on the implant abutments in each system.
It is possible to increase the reproducibility of in vitro investigations by following these suggestions. Repeated measurements on a single attachment are chosen to describe the retention of attachment materials under standard circumstances. The abutment, the retentive device, and the matrix housing must be recognised during testing. To guarantee parallelism between the attachment axis and the testing machine, blocks including male and female components should be meticulously produced. A load cell (100–500 N), a dislodging speed (50 mm/min), and a solution (artificial saliva) indicative of clinical usage should be used for force measurements.