الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Complete edentulous is not a permanent physiological condition; rather, it results in the loss of basal bone, which is unavoidable and irreversible. Patients with traditional full dentures may have significant difficulty chewing because of absence of retention, stability and support, as well as the resulting reduction in chewing capacity. Now a day, restoration for edentulous patient with a two implant assisted overdenture, either splinted or un-splinted implants. Un-splinted attachments have the benefit of requiring less inter-arch space, being simpler to clean, and being less expensive and easier to manufacture than splinted attachments. Heat cured (PMMA) has a number of mechanical and physical problems, such as lower impact and fatigue strengths, as well as low thermal conductivity and hardness, to reinforce the acrylic denture base a variety of techniques for denture base reinforcement have been developed. Metal reinforcement, rubber-reinforced poly-methyl methacrylate, fillers such as carbon fiber, aramid fibers, glass fiber, Nylon, Hydroxyapatite, and nanoscale reinforcing materials were all mentioned. Poly-ether-ether-ketone (PEEK) is frequently utilized in dentistry and is seen as a viable alternative to traditional materials.
Aim of the study: The aim of the study is to compare two different denture base reinforcement materials cobalt-chromium (CoCr) and Poly-ether-ether-ketone (PEEK) in comparison to conventional acrylic denture bases on strain around two implant-assisted mandibular overdentures and on ridge area.
Materials and methods: (3 epoxy models) were used. Two implants were retained bilaterally in the canine area of each edentulous epoxy mandibular model. 24 mandibular overdenture were constructed and divided into 3 groups group; A (control group), group B (study group), and group C (study group). For (group A) the acrylic denture base is without reinforcement, for (group B) and (group c) the acrylic denture base will be reinforced by (CoCr, PEEK) respectively. Six linear strain gauges were fused to the epoxy model at the mesial and distal surface of each implant, as well as under the mesial fossa of lower first molars on the right and left ridge area. Each gauge were connected independently into a 1/4 Wheatstone bridge of a multichannel digital amplifier. Using a loading apparatus, strain measurements were taken under central and unilateral loading around the two implants, as well as on the ridge regions. Results: The results revealed that there was no significant difference between all groups upon application of central load of 100N on ridges. However, PEEK (group C) showed lower strain values upon application of central and unilateral loading of 100N around the implant and on the ridge. Conclusion: PEEK reinforcement material showed lower strain values with favorable stress distribution when compared to Acrylic and cobalt chromium reinforcement material for implant-assisted mandibular overdenture.