Functional Evaluation for 3D Printed Complete Dentures

1. Introduction In recent years, advances in digital technology have led to a growingbody of research on digital complete dentures. For example, in challengingsingle‐arch complete denture cases involving an irregular opposing occlusal plane,digital technology can simplify conventional procedures, including adjustment of theopposing dentition and accurate transfer of the adjusted occlusal scheme to thedefinitive denture. Digital denture workflows can effectively reduce the number ofpatient visits. Moreover, the number and duration of clinical adjustments requiredafter denture delivery do not differ significantly between digital and conventionaldentures. Digital denture fabrication methods can generally be divided into twocategories: additive manufacturing and subtractive manufacturing. Additivemanufacturing, commonly known as three‐dimensional (3D) printing, offers severaladvantages, including convenience, rapid production, and relatively low cost. Itsdisadvantages include comparatively weaker material properties and limited estheticsbecause of the relatively uniform color of printed dentures. Subtractivemanufacturing involves milling the denture from a prefabricated material block.Because these materials are industrially polymerized in advance, they generally havegreater strength and dimensional stability than 3D‐printed materials. However,milling results in greater material waste and higher manufacturing costs.Several studies have evaluated the adaptation of 3D‐printed dentures. Comparisonsinvolving different printing techniques and printing orientations have demonstratedthat the adaptation of 3D‐printed dentures is comparable to that of denturesfabricated using the conventional pack‐and‐press technique. An intraoral clinicalstudy also demonstrated that digitally fabricated dentures, whether produced through3D printing or milling, provide sufficient accuracy and intraoral adaptation forclinical use.During the processing of conventional complete dentures, substantial materialdeformation may occur during flasking and polymerization. This deformation can causedisplacement of the artificial teeth and result in occlusal discrepancies. Aclinical study by Saurabh et al. reported that digitally fabricated denturesresulted in less displacement of the artificial teeth and required fewer adjustmentsafter fabrication than conventional dentures.Digital technologies for removable denture fabrication continue to evolve, withongoing improvements in both accuracy and material strength. Nevertheless,additional studies are required to clarify the differences in their actual clinicalperformance.In that study, intraoral scanning was used to obtain impressions for digital denturefabrication. For edentulous ridges, impressions obtained exclusively throughintraoral scanning may provide less adequate border extension than conventionalimpressions made using custom trays. This is because the oral mucosa and surroundingsoft tissues are mobile, making the scanning conditions fundamentally different fromthose encountered during the fabrication of fixed prostheses. Therefore, completedentures fabricated solely from intraoral scans may have less favorable borderextension and peripheral sealing than conventionally fabricated dentures,potentially resulting in reduced stability and masticatory efficiency.In another intraoral clinical study, a custom tray was fabricated following apreliminary impression using the conventional workflow. Border molding and adefinitive impression were subsequently performed intraorally. After the master castwas produced and the artificial teeth were arranged, the denture setup was scannedto create a standard tessellation language (STL) file. The same digital file wasthen used to fabricate both a 3D‐printed denture and a milled denture. After thepatients had worn each denture for a specified period, the two dentures werecompared. Patient satisfaction with both digital dentures was greater than that withtheir existing dentures. The digital dentures also demonstrated favorable intraoralstability, comfort, esthetics, speech, and occlusal performance.These findings indicate that the quality of digital dentures is sufficiently stableand acceptable for clinical use. However, the intraoral performance of thedefinitive denture depends on obtaining an accurate and complete impression andrecording the maxillomandibular relationship precisely. Although conventionalprocedures can provide a complete definitive impression, they do not reduce thenumber or duration of clinical procedures. Therefore, it is important to investigatehow digital technologies can be integrated into the conventional complete dentureworkflow to obtain complete and accurate impressions, reduce the number of patientvisits, and produce definitive dentures whose clinical performance is comparable tothat of conventionally fabricated dentures. 2. Study Objective The objective of this study is to compare the clinical performanceof digitally fabricated and conventionally fabricated complete dentures. After eachparticipant has worn both types of dentures for a specified period, theirperformance will be evaluated using objective clinical assessments and subjectivepatient‐reported outcome measures. The study will determine whether digitallyfabricated complete dentures provide superior or comparable clinical performance toconventional complete dentures. 3. Study Design This study is designed as a randomized, single‐blinded crossoverclinical trial. Participants will be randomly allocated to two groups, with ananticipated enrollment of five participants per group and a total sample size of 10participants.Group 1: Participants will first wear conventionally fabricated complete dentures for sixweeks and will subsequently wear digitally fabricated 3D‐printed complete dentures forsix weeks. Questionnaires and clinical performance assessments will be administered aftereach six‐week intervention period.Group 2: Participants will first wear digitally fabricated 3D‐printed complete denturesfor six weeks and will subsequently wear conventionally fabricated complete dentures forsix weeks. Questionnaires and clinical performance assessments will be administered aftereach six‐week intervention period.Clinical Procedures Conventional complete denture workflowAt the first visit, preliminary impressions will be obtained using alginate, anddiagnostic casts will be produced. Custom acrylic resin impression trays willsubsequently be fabricated using autopolymerizing resin (Ostron, GC Co.).At the second visit, border molding will be performed using the custom trays andthermoplastic border‐molding compound (Peri Compound, GC Co.). Definitive impressionswill then be obtained using a silicone impression material (Exadenture, GC Co.), and themaster casts will be produced. Record bases and occlusion rims will subsequently befabricated on the master casts.At the third visit, the record bases and occlusion rims will be used to determine theocclusal vertical dimension and record the centric relation. The master casts will thenbe mounted on an articulator, and the artificial teeth will be arranged.At the fourth visit, the trial dentures will be evaluated intraorally to assessesthetics, speech, and occlusion. If no problems are identified, the dentures will beprocessed using the conventional flasking and heat‐polymerization technique.At the fifth visit, the definitive dentures will be adjusted and delivered. Follow‐upadjustments will be performed 24 hours, three days, and one week after denture delivery.After the participant has worn the dentures for six weeks, clinical performanceassessments will be conducted, and fabrication of the second set of dentures will begin.Digital complete denture workflowAt the first visit, preliminary impressions will be obtained using alginate, anddiagnostic casts will be produced. The casts will be digitized using a 3Shape scanningsystem. Record bases will then be designed digitally and fabricated using a 3D printer(NextDent 5100) and a printable material (NextDent Try‐In). Wax occlusion rims willsubsequently be fabricated on the printed record bases.At the second visit, the record bases and occlusion rims will be used to determine theocclusal vertical dimension. Border molding and peripheral sealing will be performedusing a thermoplastic border‐molding compound. A definitive closed‐mouth impression willthen be obtained using a silicone impression material while the participant occludes atthe predetermined vertical dimension. The dental midline and occlusal plane will bemarked on the occlusion rims, and facial photographs will be obtained.After the master casts are produced from the definitive impressions, they will be scannedto create STL files. The facial photographs will be integrated into the denture designsoftware to assist with the digital arrangement of the artificial teeth. After completionof the design, the definitive complete dentures will be fabricated directly using a 3Dprinter and NextDent Denture 3D+ material.At the third visit, the dentures will be evaluated intraorally, the occlusion will beadjusted, and the definitive dentures will be delivered. Follow‐up adjustments will beperformed 24 hours, three days, and one week after denture delivery. Clinical performanceassessments will be conducted after the participant has worn the dentures for six weeks.At the end of the study, each participant will be allowed to select the set of denturesthat they prefer to continue wearing.