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Statement of the problem: All on four immediate function approach rehabilitating mandibular arch is a successful rout of treatment for resorbed ridges, however its outcome depends on amount of stresses transferred to the surrounding structures. To improve mechanical properties of dental structures, stress analyses under various loading circumstances has become an integral part of researches. This study aimed to assess the effect of three different framework materials on stress distribution over implants and bone simulating materials using finite element analyses. Materials and methods: Three-dimensional finite element model was created. Bone and mucosa were modeled with simplification. The modeled parts were transferred to ANSYS for assembly, meshing, and analysis. The framework materials were (Cr Co, Titanium, and PEEK) to be studied under vertical and lateral loads. Results: Bone sensitivity to framework material was demonstrated as, increasing material elasticity reduces bone stresses. While total bone deformation of Cr Co and Titanium frameworks were equivalent, PEEK material showed the highest deformation. All implant complex components showed increasing stresses and deformation with reducing material elasticity. Under the proposed loads, no failure occurred in any model component. Conclusion: Within this study limitations, all materials tested were found to be suitable for usage as all on four system framework. Cr Co material showed the best performance, while Titanium was found nearly equivalent to it, and PEEK caused the highest stresses and deformations on bone and implant complex.

Background: Denture base materials are subjected to sorption, a process of absorption and adsorption of liquids depending on the environmental conditions, also their fitting surface is subjected to microbial adhesion due to surface irregularities. Soft silicon liners are usually used with removable appliances to decrease load concentration on the hard and soft tissues. Silicon liners also undergo fluid sorption and microbial adhesion.Aim: This study was carried out to assess the effect of standardizing the oral hygiene conditions on the microbial load difference between conventional acrylic denture bases and silicon soft relining material (Mucopren soft) used to reline mandibular complete dentures in atrophied mandibles. Methods: Conventional complete dentures were constructed for 25 patients with flat atrophic mandibular ridges to be used for two weeks, salivary swabs were collected to evaluate oral flora attached on the fitting surface of the denture base and the buccal vestibule, soft liner was applied for all patients mandibular denture surfaces and the same approach was repeated after two weeks of the liner use. Results: Microbial load was found to be significantly higher in the fitting surfaces of the silicon soft liner, than in the conventional acrylic base fitting surfaces.Conclusion: Even under controlled oral conditions, Mucopren soft silicon liner incorporates greater microbial load than acrylic material thus, subjecting patients to numerous infections.

Introduction: Utilization of removable partial dentures (RPD) is inevitable in some patients that are not indicated for any other treatment option, thus patient satisfaction with this line of treatment is of great importance. However, a notable need exists to advance materials and fabrication technologies due to the undesirable health outcomes linked with current RPDs. Aim: In this study patient satisfaction with conventionally manufactured metal RPD framework, was compared with their satisfaction using digitally milled PEEK (Juvora) framework. Methods: Ten patients were selected having class I partially edentulous mandibles. A conventional metal framework RPD was constructed for each patient, then another RPD with milled PEEK framework was digitally fabricated for each one of them. Each patient had the chance to use each denture for three months, then questionnaires were filled to assess their satisfaction. Results: The questionnaires were statistically analyzed and resulted in more patients’ satisfaction with the digital PEEK framework RPD, than with conventional metallic RPD framework.Conclusion: PEEK material increases patients’ satisfaction with RPDs than the conventional metal framework material, thus decreasing patients’ complaints from removable appliances.