The effect of addition of barium sulphate nanoparticles on some properties of Acetal resin

Abstract

. IntroductionPatient needs a removable denture for the purpose of functional, psychological or financial. Construction of an esthetic removable denture with minimal display of conventional metal clasp makes a challenge to the dentist. 1 Continous research in polymer science has provided "Acetal resin" (Polyoxymethylene (POM)), which is made by the polymerization of formaldehyde and is a thermoplastic technopolymer with a monomer-free crystalline structure.2 Acetal resin is a thermoplastic and injection moulded resin. It has been used as alternative denture base and denture clasp material since 1986. It was used as a clasp material due to superior aesthetics which made the clasp match the shade of the abutment tooth.3 It is very strong, resists wear and fatigue, in addition to flexiblity, which makes it the best material for pre-formed clasps of partial denture, unilateral partial denture, provisional bridges, implant abutments, occlusal splints and orthodontic appliances.4 Acetal resin and polymethyl methacrylate (PMMA) are radiolucent materials that cannot be seen using standard radiographic techniques. So in cases of accidental ingestion, aspiration traumatic impactions of the dental appliance, it is difficult to be detected and requires invasive procedures as advanced imaging techniques. Delay in localizing or removing the foreign body may be harmful to the life. 5 Much research has been carried out to incorporate radio-opaque material such as metals, iodobenzene, polybarium acrylate and barium sulphate into the acrylic resin to fabricate a reasonable radio-opaque denture base material. 6 The effect of radiopaque material with the BaSO 4 was tested on the mechanical and physical properties of Background and objective: Acetal resin or polyoxymethylene is a flexible thermoplastic radiolucent denture base material. This study aimed to evaluate the addition of barium sulfate BaSO 4 nanoparticles on the mechanical and physical properties of acetal resin. Methods: Forty two specimens were prepared from both non-modified and modified acetal resin. The tested specimens were obtained by melt extrusion into the mold equipment followed by injection molding. The radio-opacity of non-modified and modified evaluated, and then some mechanical and physical properties tested. Results:The results of radio-opacity test showed that the radiographic density of BaSO 4 3% Acetal resin specimens was at the same level of 2mm thickness of the aluminum stepwedge. Non-significant decrease noted in surface roughness, creep in all strain regions, and compressive strength and modulus of elasticity. Conclusion: It has been concluded that the addition of 3% BaSO 4 nanoparticles produced an acceptable radio-opaque Acetal resin denture base material. Although the addition caused some changes in properties, the modified Acetal resin remained as a flexible thermoplastic material.

Color Stability of Re-Injection Acetal Resin with Different Percentages or Several Times

“…The flexite company first proposed Rapid Injection Systems in 1962. The business unveiled the first Flexite thermoplastic resin, a fluoropolymer (a material similar to Teflon) (17,18) . In 1971, acetal was used for the first time as an indestructible thermoplastic polymer.…”