Additive manufacturing is becoming an increasingly important technique for the production of dental restorations and assistive devices. The most commonly used systems are based on vat polymerization, e.g., stereolithography (SLA) and digital light processing (DLP). In contrast, fused filament fabrication (FFF), also known under the brand name fused deposition modeling (FDM), is rarely applied in the dental field. This might be due to the reduced accuracy and resolution of FFF compared to vat polymerization. However, the use of FFF in the dental sector seems very promising for in-house production since it presents a cost-effective and straight forward method. The manufacturing of nearly ready-to-use parts with only minimal post-processing can be considered highly advantageous. Therefore, the objective was to implement FFF in a digital dental workflow. The present report demonstrates the production of surgical guides for implant insertion by FFF. Furthermore, a novel approach using a temperature-sensitive filament for bite registration plates holds great promise for a simplified workflow. In combination with a medical-grade filament, a multi-material impression tray was printed for optimized impression taking of edentulous patients. Compared to the conventional way, the printed thermoplastic material is pleasant to model and can allow clean and fast work on the patient.

Accuracy is an important parameter of additively manufactured objects. The influence of post-processing on the objects, in particular the effects of monomer contamination in isopropanol used during the post-rinsing of parts produced by vat photopolymerisation, is therefore important. Forty test specimens were fabricated from standard dental resin and divided into four groups, each rinsed with isopropanol containing 0 wt%, 10 wt%, 20 wt% or 30 wt% resin contamination. Optical scans of the specimens were compared with the original design to assess dimensional deviations. The results showed no significant deviations at contamination levels up to 10 wt%. At 20 wt%, deviations were observed in small structures and inclined planes, while 30 wt% contamination resulted in significant deviations in all areas. Rinsing with 99.9% isopropanol consistently produced the highest accuracy. Resin build-up below 10 wt% did not affect dimensional stability, suggesting that isopropanol replacement is unnecessary at this level. However, a contamination level of 20 wt% can lead to deviations under certain conditions, and a contamination level of 30 wt% consistently affects accuracy. These findings highlight the importance of monitoring contamination levels to maintain the integrity of vat photopolymerisation workflows and suggest that isopropanol should be replaced at contamination levels approaching 30 wt%.

This study evaluated the bonding strength, fatigue survival, and fracture modes of dentures fabricated through conventional, additive (SLA/DLP), and subtractive CAD/CAM workflows to test their clinical durability after simulated oral ageing. Eight denture base-tooth combinations ( n = 8 per group) were produced using either heat-polymerised PMMA, additively manufactured resins (Formlabs Denture Base LP or Voco V-Print Dentbase) or subtractively milled PMMA (Voco CediTec DB). Prefabricated (VITA Vionic) or CAD/CAM-fabricated denture teeth were then bonded. Surface roughness was quantified using laser scanning microscopy and the degree of conversion using Raman spectroscopy. The specimens underwent hydrothermal ageing with dynamic loading (1.2 million cycles at 5 °C/55 °C) followed by quasi-static shear fracture testing and fracture mode analysis. The conventional fabricated cast-on samples achieved the highest mean fracture load both before (445.7 ± 49.2 N) and after aging (411.7 ± 45.7 N) with 100% survival. Additive workflows (SLA/DLP) groups showed cohesive failures pre-aging; however, the DLP workflow demonstrated a 57% strength reduction post-aging ( p = 0.0057) and 87.5% survival. Subtractive groups had the lowest survival rates (50–62.5%), significant strength losses ( p < 0.05), and predominantly adhesive failures at the tooth-base interface. Ageing significantly affected bond strength in selected additive and subtractive groups ( p < 0.05), whereas the conventional cast-on group remained unaffected. Conventional heat-polymerized PMMA bonded to prefabricated teeth remains the benchmark for denture fabrication. Additive CAD/CAM workflows approach similar performance, whereas subtractive methods require further optimization to improve bond stability under hydrothermal fatigue.