Life cycle assessment evidence for digital dental workflows: a scoping review and evidence map of additive manufacturing, subtractive CAD/CAM, and conventional care

Digital dentistry is often presented as a dematerialized and more sustainable alternative to conventional dental care. However, this assumption is methodologically insufficient, because digital workflows may reduce visible clinical materials while introducing new burdens related to scanners, design workstations, milling units, 3D printers, post-processing systems, electricity use, software infrastructure, logistics, waste and end-of-life management. Robust environmental claims therefore require life cycle assessment based on clinically meaningful functional units, comparable system boundaries and multi-category life cycle impact assessment. This scoping review evaluates current life cycle assessment evidence for digital dental workflows, with emphasis on additive manufacturing, subtractive CAD/CAM and conventional care. Searches covered OpenAlex, Crossref, PubMed, ISO records, professional organization materials and institutional sustainability reports; searches were conducted between January and May 2026, with the final source log verified on 4 May 2026. A PRISMA-ScR-informed flow identified 702 records, removed 84 duplicates, screened 618 unique records, assessed 363 reports for eligibility against broad inclusion criteria, and retained 30 core sources for structured narrative synthesis. Direct dental life cycle assessment evidence remains sparse and heterogeneous, with available evidence for dental examinations, restorative materials, post-orthodontic retainers and emerging removable partial denture fabrication workflows involving intraoral scanning. The strongest direct signal for digital substitution comes from modeled removable partial denture fabrication scenarios using alginate impressions as the conventional comparator, where digital workflows reported 65.22 kg CO₂-eq and 78.63 kg CO₂-eq compared with 77.29 kg CO₂-eq and 94.67 kg CO₂-eq for corresponding traditional workflows, equivalent to approximately 16–17% lower emissions under modeled assumptions. These findings remain indication-specific and sensitive to appointment structure, laboratory geography, electricity mix, transport, equipment utilization, remake rates and waste treatment assumptions. Overall, digital dental workflows are not inherently sustainable. They may reduce environmental burden when they decrease appointments, material use, transport and remakes without adding disproportionate energy, equipment, post-processing or hazardous waste burdens. Current evidence does not justify pooled quantitative conclusions. Future studies should use clinically equivalent functional units, cradle-to-grave boundaries, transparent inventories, multi-category life cycle impact assessment, explicit uncertainty analysis and extreme scenario sensitivity testing before comparative sustainability claims or meta-analyses are attempted.