Related Experiment Video
Updated: Aug 7, 2026
Force System with Vertical V-Bends: A 3D In Vitro Assessment of Elastic and Rigid Rectangular Archwires
Published on: July 24, 2018
Effect of polymerization unit and support bar design on the trueness and fit of additively manufactured
Manuel Aeschbacher1, Steven Sonderegger1, Seyed Ali Mosaddad2
1Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.
Objective:
This study evaluated the influence of polymerization units and support bar design on the trueness and fit of complete-arch implant-supported frameworks fabricated using digital light processing (DLP) additive manufacturing (AM) and compared their performance with a subtractively manufactured (SM) control.
Methods:
A maxillary complete-arch framework was designed and fabricated using six conditions combining two polymerization units (xenon-flash light under nitrogen [XFN] and light-emitting diode [LED]) and three support bar designs (no-bar, Y-shaped bar, horizontal-bar), along with an SM reference framework (n = 10). Fabrication trueness was evaluated by analyzing surface deviations across predefined regions (overall framework, occlusal, non-occlusal, and abutment surfaces) and by measuring linear abutment-level and interimplant distance deviations using metrology software. Marginal gap, used as a fit indicator, was assessed using a digital triple-scan protocol. Test and control group differences were analyzed by one-way ANOVA (Dunnett), and those across AM groups by two-way ANOVA (Bonferroni; α = 0.05).
Results:
Support bar design significantly influenced trueness (p < 0.001); no-bar frameworks generally demonstrated the highest trueness. The polymerization unit showed limited main effects on trueness, although a significant effect was observed for overall RMS (p = 0.024). For linear deviation, interimplant distance, and marginal gap, outcome-dependent polymerization unit × support bar design interactions were identified (p < 0.05). XFN polymerization yielded lower linear deviations at selected implant sites, whereas LED polymerization was associated with lower interimplant distance deviations and reduced marginal gaps at specific locations.
Conclusions:
Support bar design was the primary factor influencing dimensional trueness, with no-bar configurations generally demonstrating higher trueness. Polymerization unit effects were outcome- and geometry-dependent, with no consistent overall difference between XFN and LED.
Clinical Significance:
Under the tested laboratory conditions, omitting support bars was associated with lower surface deviations in DLP-printed frameworks. However, the site- and geometry-dependent marginal gap findings do not establish a clinically preferable support or polymerization protocol and require mechanical and clinical validation.
