INTRODUCTION:A direct link was found between surface roughness, the accumulation of plaque and the adherence of microorganisms concerning acrylic resins. However, the surface properties of the new thermoplastic materials remain questionable especially after using the conventional finishing and polishing techniques. Studying surface properties of each material makes the recommendation of the proper techniques easier. OBJECTIVES: This in vitro study intended to compare three types of denture base materials in regarding to the effect of different polishing techniques on their surface roughness. MATERIALS AND METHODS: 36 specimens were incorporated in this study. 12 specimens were in each group. 3 groups were formed: Group A: Heat cured Polymethylmethacrylate (PMMA). Group B: Thermoplastic Polyamides. Group C: Thermoplastic Acetal. Dimensions of specimens were (20×20×3 mm) with projection at the side. Statistical analysis was carried out using two way analysis of variance (ANOVA). Statistical significance was defined at P≤0.05. RESULTS: Technique no. 1 showed a high significant value in compared to technique no.2 for polishing the tested materials. CONCLUSIONS: PMMA was the highest affected group followed by thermoplastic acetal and the last affected group was thermoplastic polyamide. Prepolishing rubberizing with rubber bur improves the polishing procedure. RESULTS: Remarkable improvement in the histology and the ultrastructure of the alveolar bone of rats in Group III was observed. Moreover, hematological values revealed significant decrease in the inflammatory condition of rats with induced RA after fish oil treatment. CONCLUSIONS: Rheumatoid arthritis is an important risk factor for alveolar bone loss. The treatment of the RA induced rats with fish oil not only prevented the alveolar bone resorption and stimulated new bone formation, but also reduced relatively the level of rheumatoid factor in the blood.

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AIM: The study was conducted to evaluate maximum biting force (MBF) in two different attachment systems (bollard a vs. ball and socket attachment) retaining mandibular overdenture using a split-mouth design. SUBJECTS AND METHODS: Twelve completely edentulous patients received complete dentures and after adaption of the patient with the new denture, 24 implants were inserted in the canine region using two-stage surgical technique and conventional loading protocol. Six patients received the Bollard attachment at the right side and the Ball and Socket at the left side. Moreover, the other six patients received the bollard attachment at the left side and the ball and socket attachment at the right side. Each patient was treated according to split-mouth design. Insertion of each of the attachment type was assigned randomly. Using occlusal force meter instrument, MBF was measured immediately after loading (0), after 6 months (6), and after 12 months (12). RESULTS: Significant statistical differences (p < 0.05) were obvious in in MBF between Attachment (1) and Attachment (2) immediately after loading (0 months), after 6 months (6) and after 12 months (12) follow-up visits. CONCLUSION: Mandibular implant retained overdenture received Bollard abutment that retained with the denture by the help of resilient liner “Retention.sil”* without housing have higher biting forces than mandibular implant retained overdenture with ball abutment where the plastic house was picked up by monomer free self-cured acrylic resin.

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