Study On The Preparation And Properties Of Materials Used For Invisible Treatment

Since the invention of invisible orthodontic treatment technology,it is loved by the majority of dental patients and orthodontists because of its good treatment effect.However,the core technology and raw materials of this technology are very confidential and many dental hospitals still use imported materials.Research on the raw materials of invisible orthodontic appliances is less in our country and there is no performance standard for invisible orthodontic materials.In this paper,the performance of imported materials(Erkodur hot pressed diaphragm)was analyzed and the performance standard of invisible orthodontic materials was formulated.Co-polyester PETG was selected as the matrix material,and PC(polycarbonate)and TPU(thermoplastic polyurethane elastomer)were added for blending modification.The transparency,saliva absorption rate,hardness performance,mechanical properties and other properties of PETG/PC/TPU blends with different mass ratios were studied and PETG/PC/TPU blends which meet the performance standard were used to prepare invisible orthodontic appliances by vacuum hot-pressing molding technology.The main works are as follows:(1)The properties of imported materials(Erkodur hot pressed diaphragm)were analyzed.The mechanical properties,transparent properties,saliva absorption rate,hardness performance,and other properties were studied and the performance standard of invisible orthodontic materials was formulated.(2)PC is used to strengthen PETG.With the content of PC increasing,the tensile yield stress and tensile elastic modulus of PETG/PC blends increase,the elongation at break decreases,the light transmittance is over than 82%,the saliva absorption rate decreases,and the hardness increases.When the PETG/PC is 80/20,the transmittance of the blends is 88.9%,the haze is 4.3%,the tensile yield stress is 51.2 MPa,the elongation at break is 123%,the tensile elastic modulus is 1632 MPa,the saliva absorption rate is 0.445%and the hardness is 84.7D.The elongation at break of the blends is lower than the performance standard,and the processing performance of the blends becomes poor at the same time.(3)The PETG/PC blends which had fixed mass ratio 80/20 were modified by adding 5,10,15 and 20 phr TPU.When the content of TPU is 10 phr,the transmittance of the blends is 87.9%,the haze is 5.2%,the tensile yield stress is 47.8 MPa,the elongation at break is 132%,the tensile elastic modulus is 1588 MPa,the saliva absorption rate is 0.479%and the hardness is 84.3D.The comprehensive performance is close to the performance standard and the PETG/PC/TPU(mass ratio 80/20/10)blends can be used to prepare invisible orthodontic appliances.(4)The PETG/PC/TPU(mass ratio 80/20/10)blends were prepared and were injected into film.Finally,the film was used to prepare invisible orthodontic appliances by vacuum hot-pressing molding technology on the ERKOFORM 3D+ laminating machine.The heat temperature is 160 ?.The invisible orthodontic appliances we prepare are basically similar to imported appliances in appearance and performance.