This prospective randomized crossover clinical trial evaluates and compares the clinical performance and oral health-related quality of life (OHRQoL) of complete dentures fabricated through two additive manufacturing workflows - digital and hybrid - in edentulous patients attending the Dental Clinic of Universidad de Especialidades Espíritu Santo (UEES), Samborondón, Ecuador.
In the digital workflow, complete dentures are fabricated using direct intraoral scanning of edentulous ridges, CAD design, and 3D printing. In the hybrid workflow, conventional functional impressions are digitized, followed by CAD design and additive manufacturing of the definitive dentures.
Each eligible participant receives two complete denture sets in a randomized crossover sequence (no washout period): Denture Set 1 is worn for 2 months, after which the participant crosses over to Denture Set 2, worn for an additional 2 months. Total active follow-up per participant is approximately 4 months. Following completion of the crossover phase, denture wear is monitored longitudinally for 12 months from the insertion of the second denture set (total study duration approximately 16 months per participant).
The study addresses three specific objectives:
To determine the clinical success rate of complete dentures fabricated by additive manufacturing under digital and hybrid workflows, evaluating retention, stability, denture base adaptation, occlusal balance, and need for clinical adjustments.
To evaluate the impact of complete denture treatment on OHRQoL using the validated OHIP-EDENT questionnaire, assessed at the insertion of each denture set and at the 2-month control of each period (4 measurement points total).
To evaluate the relationship between maximum masticatory force (T-Scan digital occlusal analysis system) and denture wear (volumetric 3D digital metrology via STL superimposition), with wear monitored over 12 months from insertion of the second denture set.
Completely edentulous (bimaxillary)
Age between 50 and 90 years
Able to understand and sign informed consent
No cognitive or psychological deficits that interfere with study participation
Unimaxillary edentulism
Presence of Kelly syndrome
Presence of flabby tissue on alveolar ridges
No prior experience with complete dentures
Crossover
Digital Workflow Complete Denture
DeviceComplete dentures fabricated using direct intraoral scanning of edentulous ridges (TRIOS 5, 3Shape), CAD design (3Shape Dental System), 3D-printed try-in prototype (Asiga TRY resin, Asiga MAX 2 printer), and definitive 3D-printed denture (DentaBASE resin; VarseoSmile TriniQ teeth, BEGO). Completed in 3 clinical appointments.
Hybrid Workflow Complete Denture
DeviceComplete dentures fabricated using conventional preliminary and functional impressions (elastomeric materials), interocclusal registration with wax rims, conventional wax try-in, digitization of the impression/master model via laboratory scanner, CAD design (3Shape Dental System), and additive manufacturing of the definitive denture base (DentaBASE resin; VarseoSmile TriniQ teeth, BEGO). Completed in 5 clinical appointments.
Oral Health-Related Quality of Life - OHIP-EDENT Total Score
19-item validated questionnaire (Allen \& Locker, 2002). Each item scored 0 (never) to 4 (very often). Higher scores indicate worse OHRQoL. Assessed at 4 time points across the full crossover period to capture quality of life evolution under each workflow.
Clinical Success Rate
Composite endpoint assessed by a calibrated blinded examiner using a standardized clinical form (adapted from Peroz et al.), including: denture base extension and border molding accuracy, bilateral balanced occlusion, retention by vertical traction test (good/moderate/deficient), stability during mandibular movements, phonetic evaluation (/s/, /z/, /f/), and need for clinical adjustments.
Maximum Masticatory Force
Relative occlusal force intensity and distribution recorded by the T-Scan digital occlusal analysis system (Tekscan Inc., Norwood, MA, USA) during maximum voluntary clenching. Parameters: total maximum force (relative units), right/left hemiarcade distribution, anterior/posterior distribution.
Denture Wear - Volumetric Surface Loss
Volumetric loss (mm³) of occlusal surfaces quantified by 3D superimposition (best-fit alignment) of STL models obtained by intraoral or laboratory scanning. Baseline scan obtained at delivery of each denture set. Longitudinal monitoring of Set 2 wear conducted over 12 months from its insertion.
Correlation Between Maximum Masticatory Force and Denture Wear
Pearson or Spearman correlation coefficient between T-Scan maximum force values and cumulative volumetric denture wear at each follow-up time point, for each workflow and overall.
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