A comparison of mechanic properties regarding complete removable dentures, which were made from polymethylmethacrilate (PMMA) during conventional and CAD/CAM processes. Systemic literature review.

Background: It is not clear if complete removable dentures made during a CAD/CAM process can equate or surpass dentures created during the conventional process in regards of their mechanical properties.

Purpose: To compare mechanical properties of complete removable dentures made from polymethylmethacrilate (PMMA) during a process of CAD/CAM, which are used to help edentulous adult patients, with analogical dentures created from PMMA during the conventional process.

Material and methods: Data search was conducted regarding PRISMA criteria. According to chosen keywords, scientific articles, published from 2017 to 2022, were sampled from electronic databases such as PubMed, Science Direct, and Cohrane Library. Article search focused on studies that discussed mechanic properties of traditional and CAD/CAM complete removable dentures made from PMMA. The properties are: microhardness, nano hardness, the roughness of the surface, flexural strength and modulus, fracture toughness, flexural bond strength, mechanical compliance of the contact between the inner surface of the denture and the denture socket mucosa - adaptation of the prosthesis to the denture bearing, hydrophobicity, water sorption and solubility, dimensional stability, elasticity. Discussed measurements from the scientific studies, which are included into the systematic literature analysis, are assessed according to a synthesis method used for such data.

Results: The hardness, flexural strength, flexural modulus, and hydrophobicity of the conventional PMMA plastic blank, made during a process of CAD/CAM, were bigger and dimensional stability - better. Meanwhile, the roughness of the surface, fracture toughness, flexural bond strength, and elasticity of the blank were bigger than the ones made during the conventional process. Water sorption and solubility statistically did not differ among differently processed plastic polymethylmethacrilate blanks. Only one study was carried out in vivo, in which complete removable denture bases made from CAD/CAM prepolymerized PMMA plastic also showed better adaptation to the denture bearing tissue than those made by conventional polymerization.

Conclusions: The final plastic product from the pre-polymerized PMMA and the processed CAD / CAM is superior in many mechanical properties to the final plastic product made during the conventional PMMA polymerization process.