الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Endosseous dental implants are a surgical tool placed into the jaw bone to support a prosthetic dental or orthodontic device. Ti and its alloys have long been the preferred implant material worldwide.
Denture retention, stability, and support are decreased as a result of the processing distortion caused by traditional denture procedures, which has an impact on the prosthetics’ long-term success. For edentulous patients, implant overdentures are a great therapeutic choice because they boost stability, retention, and masticatory function, which in turn improves chewing and bite power. In order to increase the stability and retention of teeth or implants supported over dentures, a number of attachment systems are used. Implants can either be splinted together with bars or unsplinted and attached individually with various types of attachments.
Titanium and its alloys are not only used as implant material but also is used as supra structure material. Its light weight and superior mechanical properties promoted its usage as bar material in implant supported overdentures.
Implant supported overdentures retained by bar are gaining more acceptance among edentulous patientas it has excellent retention capacity, reduces loading force on the implants, and helps adjust mismatched implants. In patients with an altered skeletal maxilla-mandibular relationship and horizontal/vertical bone resorption (Cawood and Howell3 classes IV, V, and VI), bar attachment is developed to overcome the anatomic limitation related to bone loss that can be difficult to treat without more complex augmentative technique.
When compared to single attachments, bar attachments have a lower incidence of prosthetic problems and a higher retention capacity and are utilized to help distribute load among the implants. Patient satisfaction with removable dentures is attributed to retention, which is a property of a prosthesis that operates to resist forces of dislodgment along the path of installation.
But Titanium has an elastic modulus that is significantly greater than that of ”bone,” and this discrepancy may lead to ”stress shielding,” a process that results in the resorption of alveolar bone.
Which sort of milled framework material would provide adequate retention values and which type of milled framework can sustain retention for a longer period of time are topics of debate.
Our study’s objective is to assess the mean retention values of three distinct milling framework attachments in implant-supported mandibular overdentures utilizing a universal testing apparatus.
Our Materials and Methods include, one edentulous mandibular acrylic resin model was built. Directing the preparation of the implant template: A stone replica of the acrylic model would serve as the foundation for an acrylic denture. To serve as a guide for implant placement, a full set of mandibular artificial teeth would be created and mounted on an acrylic denture foundation. Implant placement: Using a guide template, four parallel implants would be placed in the model’s canine and second premolar regions.
Spiral drills mounted to a parallo-meter instrument would be used to prepare the implant recesses.To replicate osseointegeration, the implant would be affixed to the models using self-initiated polymerization acrylic resin. The mandibular ridge would be covered with a robust soft liner that is 2 mm thick in order to replicate the oral mucosa. The implant would be attached to a multiunit abutment with a digital scan body and rectangular parallel side bars (extra-oral scanner).
Bar attachment was made. A screw-retained titanium bar was built. Using a CAM machine, the rectangular shape of the bars was developed and milled. Construction of sleeve frame work: Three sleeve frame work was built, each made up of a perforated base frame that was milled using a CAD/CAM system to have the same dimensions on all three bases. The construction includes Base sleeve frame work made of titanium, Base sleeve frame work made of Zirconia, Base sleeve frame work made of PEEK, A cross-shaped ring would be positioned in the geometric area, Analyzing retention forces: a- Measuring retention (vertical displacement): The ring would be fastened to the testing apparatus with an iron chain.
Prior to the measurements, the chains would be adjusted to prevent slackness. Before applying the displacement forces, each overdenture would be attached to the testing instrument. The ring would be subjected to a vertical tensile force while moving at a crosshead speed of 50 mm per minute until the attachments separate. This pace would imitate how quickly the overdenture moves away from the tissues during chewing. The highest forces necessary in newton’s (N) to move the attachments would be determined. Five times of the experiment would be performed, and the mean would be used to determine initial retention. The maximum force in newton’s (N) required moving the attachments would be determined. Every prosthesis would be put in and taken out 3240 times.
To imitate wearing a prosthesis for around three years (three insertions and removals each day for cleaning purposes), move the jaw in a vertical manner perpendicular to the occlusal plane. The ultimate retention would be represented by the mean of the following five recordings for axial displacement. Statistical evaluation: The data gathered would undergo statistical evaluation.
This laboratory study showed valid results comparable with those observed in the literature. The bar and clip attachment systems with different materials evaluated in the present study may be considered adequate for clinical usage, as retention force values were higher than the value considered minimal (5 N) for overdenture retention.
Within the limitations of the present study, the following can be concluded: CAD/CAM PEEK sleev frame work showed statistically significant superior retention values to CAD/CAM Zirconia sleev frame work, after mechanical aging simulating 3 years of clinical service, The retention strength values of both tested materials are considered to be clinically acceptable and PEEK represents a competitive candidate with Zirconia for implant supported prosthodontics, particularly in terms of retention.
Conclusion
This laboratory experiment produced reliable results that were comparable to those seen in the literature. Due to retention force values exceeding the value regarded as minimal (5 N) for overdenture retention, the bar and clip attachment systems with various materials investigated in the present study may be deemed adequate for clinical use.