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Predictability of diagnostic trial restorations fabricated as copies of diagnostic waxing using digital, analog, and
Panagiotis Ntovas1, Ourania Ladia2, Basir Barmak3
1Adjunct Faculty, Department of Prosthodontics, School of Dental Medicine, Tufts University, Boston, Mass.; Adjunct Scientific Collaborator, Division of Fixed Prosthodontics and Biomaterials, University Clinics for Dental Medicine, University of Geneva, Geneva, Switzerland; and PhD Candidate, Department of Operative Dentistry, National and Kapodistrian University of Athens, Athens, Greece.
Statement Of Problem:
Diagnostic trial restorations constitute an important tool for evaluating both function and esthetics, that can also guide tooth preparation. Various techniques have been developed for fabricating diagnostic trial restoration using conventional or completely digital workflows. Recently, hybrid workflows combining digital and analog steps have also been proposed. However, the accuracy of the trial restorations fabricated by the digital workflows, compared to those made with traditional silicone indexes, has yet to be evaluated.
Purpose:
The purpose of this in vitro study was to investigate the 3-dimensional (3D) accuracy of diagnostic trial restorations fabricated using digital and conventional workflows.
Material And Methods:
Diagnostic virtual waxing for veneer restorations was performed from second premolar to second premolar, using a cast obtained from a fully dentate patient. A total of 50 diagnostic trial restorations were fabricated using the following methods:(AM) Additive manufacturing (KeyDenture Try-In; Keystone Industries), (AMI) molding with additive manufactured index (KeyOrthoIBT; Keystone Industries), (TAMI) molding with additive manufactured index supported by an additive manufactured tray (KeyTray; Keystone Industries), (SI) molding with a silicone index (Honigum Rigid Fast; DMG) and (TSI) molding with silicone supported by an additively manufactured custom tray. The AM group was fitted onto each evaluated cast. For the remaining groups, the indexes were loaded with an autopolymerizing bis-acrylic composite resin (Luxatemp Star; DMG) and molded over the additively manufactured patient's cast. Discrepancy in thickness and 3D deviation analysis of the diagnostic waxing copies among the evaluated groups were measured on each cast using a metrology software program, with virtual diagnostic waxing serving as the reference. To assess whether statistically significant differences existed among the groups, a 2-way analysis of variance (ANOVA) was conducted (α=.05).
Results:
The discrepancy between the diagnostic trial restorations and the virtual waxing varied across different types of teeth and among different areas of the same tooth (P<.05). The mean ±standard deviation linear difference between the DTR and the diagnostic virtual waxing was 351 ±154 µm in the incisal area, 186 ±97 µm in the central, and 239 ±104 µm in the cervical section. Discrepancies were found between the investigated fabrication methods (P<.05). AM-diagnostic trial restorations showed significant lower mean linear discrepancy and RMS deviation compared to the investigated molding techniques (AMI, TAMI, SI, TSI). The use of a custom 3D printed tray to support the underlying index improved the accuracy of both conventional and additively manufactured indexes.
Conclusions:
The diagnostic trial restorations were bulkier than the digital diagnostic waxing, both for conventional and digital fabrication techniques. Additive manufacturing resulted in diagnostic trial restorations with increased accuracy compared to molding approach, regardless of the index's fabrication method.
