Milling

Milling is the most popular method of fabricating digital dentures. Once the design of the prosthesis is approved, the CAD stereolithography (STL) file is sent to a milling software that directs the milling machine to perform a series of movements. The artificial teeth may be either milled with the prosthesis (monolithic) or milled individually or as a complete arch in tooth shade material, or selected from a prefabricated series and bonded to the milled denture base (Figures 4 & 5).³⁹

Monolithic milled dentures are resistant to staining. They also help alleviate the concern of debonding of the teeth from the denture base, however, the prostheses may have a monochromatic appearance with a not-as-favorable esthetic outcome.⁵ To circumvent this problem, some manufacturers have developed resin blanks with several layers that help fabricate denture bases with polychromatic teeth that mimic the dentin and enamel thereby improving the esthetics.¹⁵ Nevertheless, esthetic constraints persist. The pre-fabricated puck defines the tooth-gingiva interface, limiting customization of tooth morphology and gingival characterization and requiring adaptation of the digital design to a predetermined scalloped junction.

Multiple studies indicate that milling provides superior overall trueness.⁴⁰ Milled denture bases demonstrate excellent fit due to the absence of polymerization shrinkage associated with conventional polymethyl methacrylate (PMMA) processing and exhibit improved dimensional stability, flexural strength, and surface hardness compared to conventional and 3D-printed dentures.^15,40-43 They also show lower surface roughness and reduced microbial adhesion compared to 3D- printed dentures. Despite these advantages, milling has notable limitations. The subtractive process results in significant material waste, as a substantial portion of the blank remains unused. Additionally, complex internal geometries and hollow structures are challenging to reproduce accurately. Machine constraints, including vertical and toolpath limitations, may restrict the fabrication of large or bulky prostheses, such as obturators, or require design compromises. Furthermore, milled dentures are generally associated with higher costs compared to 3D-printed alternatives.

Figure 4. Milled Denture Base

Image Courtesy of Dr. Goodacre

Figure 5. (A) Milled denture base (B) Prefabricated teeth bonded to the milled denture base

Images Courtesy of Dr. Goodacre

0/16Next