Additive Manufacturing of Dental Ceramics: A Systematic Review and Meta‐Analysis

Abstract

The purpose of this systematic review and meta-analysis was to evaluate the effect of using additive manufacturing (AM) for dental ceramic fabrication in comparison with subtractive manufacturing (SM), and to evaluate the effect of the type of AM technology on dental ceramic fabrication. Materials and methods: A search was conducted electronically in MEDLINE (via PubMed), EBSCOhost, Scopus, and Cochran Library databases, and also by other methods (table of contents screening, backward and forward citations, and grey literature search) up to February 12, 2022, to identify records evaluating additive manufacturing of ceramics for dental purposes in comparison with subtractive manufacturing. A minimum of 2 review authors conducted tstudy selection, quality assessment, and data extraction. Quality assessment was performed with Joanna Briggs Institute tool, and the quantitative synthesis was performed with the Comprehensive Meta-Analysis program (CMA, Biostat Inc). Hedges's g for effect size was calculated, with 0.2 as small, 0.5 as medium, and 0.8 as large. Heterogeneity was assessed with I 2 and prediction interval (PI) statistics. Publication bias was investigated with funnel plots and grey literature search. Certainty of evidence was assessed with the Grading of Recommendations: Assessment, Development, and Evaluation (GRADE) tool. Results: A total of 28 studies were included for the qualitative and quantitative synthesis; 11 in vitro studies on accuracy, 1 in vivo study on color, and 16 in vitro studies on physical and mechanical properties. Meta-analysis showed overall higher accuracy for SM compared with AM, with medium effect size (0.679, CI: 0.173 to 1.185, p = 0.009) and also for marginal (g = 1.05, CI: 0.344 to 1.760, p = 0.004), occlusal (g = 2.24, CI: 0.718 to 3.766, p = 0.004), and total (g = 4.544, CI: -0.234 to 9.323, p = 0.062) with large effect size; whereas AM had higher accuracy than SM with small effect size for the external (g = -0.238, CI: -1.215 to 0.739), p = 0.633), and internal (g = -0.403, CI: -1.273 to 0.467, p = 0.364) surfaces. For technology, self-glazed zirconia protocol had the smallest effect size (g = -0.049, CI: -0.878 to 0.78, p = 0.907), followed by stereolithography (g = 0.305, CI: -0.289 to 0.9, p = 0.314), and digital light processing (g = 1.819, CI: 0.662 to 2.976, p = 0.002) technologies. Flexural strength was higher for ceramics made by SM in comparison to AM with large effect size (g = -2.868, CI: -4.371 to -1.365, p < 0.001). Only 1 study reported on color, favoring ceramics made through combined AM and SM. Conclusions: Subtractive manufacturing had better overall accuracy, particularly for the marginal and occlusal areas, higher flexural strength, and more favorable hardness, fracture toughness, porosity, fatigue, and volumetric shrinkage; whereas AM had

Effect of CAD‐CAM restorative materials and scanning aid conditions on the accuracy and time efficiency of intraoral scans

“…Under the NSA conditions, the HC and 3YZ groups showed lower mean RMS values, whereas the M group showed the highest mean RMS value ( P < 0.05). The mean RMS values of all groups, except the HC and 3YZ groups, exceeded the clinically acceptable limit of 50 μm for the CAD‐CAM crown 51–56 . Under PSA and LSA conditions, no significant difference was observed among the materials.…”

“…The mean RMS values of all groups, except the HC and 3YZ groups, exceeded the clinically acceptable limit of 50 μm for the CAD-CAM crown. [51][52][53][54][55][56] Under PSA and LSA conditions, no significant difference was observed among the materials. For each restorative material group, the NSA condition showed a significantly higher RMS value than the PSA or LSA condition (P < 0.05), except for the HC and 3YZ groups.…”

Additively and subtractively manufactured implant‐supported fixed dental prostheses: A systematic review

“…AM zirconia seems to be more sensitive to shrinkage during the sintering process. A review evaluating the AM of dental ceramics reported favorable volumetric shrinkage for SM compared to AM (Al Hamad et al, 2022). That review also reported that an increase in the zirconia content of a suspension could lead to reduced volumetric shrinkage, whereas it might have challenging effects on factors such as the viscosity and layer thickness.…”

Effect of Surface Polishing on Physical Properties of an Occlusal Splint Material for Additive Manufacturing under Protection Gas Post-Curing Condition

“…The mainstream methods for the fabrication of dental objects using digital technologies can be classified into milling and additive manufacturing, which is well known as 3D printing [ 4 , 5 , 6 ]. As reported in previous studies, objects fabricated by milling have advantages in terms of strength and fitting accuracy [ 7 , 8 ], while additive manufacturing can provide objects with minimal cutting material waste at a low cost [ 9 ]. Generally, except for interim prostheses, milling manufacturing is recommended for the fabrication of fixed crowns and bridges that need enough strength and accurate fitting [ 10 ].…”