Qualitative aspects and minimum requirements of milling machines in digital dentistry: A narrative review

Objectives: This review focused on key outcome variables, including materials used with milling machines, accuracy, machine specifications, efficiency, automation and workflow integration, as well as maintenance and reliability. Data/sources: A comprehensive literature search was conducted across multiple databases, including PubMed/Medline, Scopus, Embase, Google Scholar, Dynamed, and Open Grey. To expand the search, the ''snowballing'' technique was also applied, identifying additional studies from the reference lists of relevant papers. The review focused on key outcome variables, including materials used with milling machines, accuracy, machine specifications, efficiency, automation and workflow integration, as well as maintenance and reliability. Study selection: The search strategy yielded 2811 records. After removing duplicates and excluding papers that did not meet the inclusion criteria, 94 papers were selected for inclusion. Conclusions: The properties of dental materials significantly influence the requirements of milling machines in prosthodontics, impacting the milling process and performance in fabricating dental restorations. CAD-CAM technology achieves satisfactory marginal fit values, though its superiority over conventional methods remains unclear. Regular calibration and quality assurance are crucial for maintaining accuracy, with specifications like spindle speed and toolpath accuracy affecting efficiency and quality. Software and connectivity improvements in dental milling expand customization options. Regular maintenance ensures consistent performance, reducing noise, predicting tool wear, and minimizing downtime. Addressing challenges and future directions will further enhance CAD-CAM milling machines in dentistry. Clinical significance: By comprehending the characteristics of materials, accuracy factors, maintenance requirements, and operational parameters, dental practitioners can optimize the utilization of milling machines, thereby achieving superior outcomes.