Accuracy of Dynamic Virtual Articulation: Trueness and Precision

Abstract

Purpose To study the effects of altering condylar settings and pin openings on the trueness and precision of virtual articulators vs. mechanical articulators. Materials and Methods Maxillary and mandibular typodonts with fiducial markers were mounted on a mechanical Artex‐CR articulator, and the mandibular teeth were prepared to allow guidance solely by the posterior determinants of the articulator and the incisal table. The relationship of the mounted typodonts was preserved digitally by scanning using manufacturer transfer plate adaptors. On the mechanical articulator, pattern resin was allowed to set between the maxillary and mandibular occlusal surfaces (area #25‐30) at the endpoints of dynamic movements at 3 condylar inclinations (SCI): 10°, 30°, and 45°, n = 12/inclination, or at 3 incisal pin openings (2, 5, and 10 mm, n = 12/opening). All other articulator settings were kept constant. Resin specimens attached to the typodonts were scanned within 5 minutes of setting, then removed, and the articulated typodonts rescanned. Fixed dental prostheses (FDPs) #25‐30 were designed on the virtual articulator using identical parameters to the mechanical articulator. Dynamic virtual movements were used to sculpt the design, and a file of the design was saved. The files of both types of samples were aligned and overlaid. Interocclusal separation was measured in triplicate at the indentation created by the mesiolabioincisal point angle on the incisal edge of #8 and the mesiobucco‐occlusal point angle of #3. Trueness and precision of both types of articulators were calculated and compared using one‐way ANOVA, followed by the Tukey HSD test (α = 0.05). Results There was no statistically significant difference at altered pin openings in either trueness (F = 0.202, p = 0.37) or precision (F = 3.134, p = 0.09) for the majority of measurements. The only significant difference was in the precision between the 2 types of articulators at 5 mm incisal opening, and only at the anterior measurement point (F = 15.134, p = 0.0008); however, these differences were less than 100 μm. When the SCI was altered, there was no statistically significant difference (F = 3.624, p > 0.05) between the virtual and mechanical articulators in trueness for 5 of the 6 measurements obtained (F = 3.624, p = 0.07) or for all of the precision measurements (F = 3.529, p = 0.07). The one trueness measurement that was significantly different (F = 9.237, p = 0.006) occured at SCI of 10°, and it was less than 100 µm. Conclusions Dynamic movements on the virtual articulator were shown to be as true and precise as to the mechanical articulator. When there were deviations, these deviations were less than 100 µm and thus, these deviations may not be clinically relevant.

Virtual Articulators and Virtual Mounting Procedures: Where Do We Stand?

“…The virtual contacts observed are more accurate than those obtained using an analogue approach, provided that the virtual procedure is performed with appropriate software and recording techniques 17,30‐33,35,36 . Additionally, virtual dynamic movements on a VA exhibit similar accuracy to those reproduced on a MA 34 . Virtual assembly in a VA will likely find indications in the study of cases that require repositioning of the arches in CR 37 .…”

“…The accuracy of different VA systems has been investigated, comparing the Dental Designer Software (v17.2.1; 3Shape, Copenaghen, Denmark) with a MA (Artex‐CR articulator; Amann Girrbach, Koblach, Austria). The data showed that the two systems produced similar results 34 . Some differences between registration systems in their ability to simulate mandibular movements have been reported, but the speed at which this technology is evolving makes scientific analysis difficult 3,34 …”

“…The data showed that the two systems produced similar results 34 . Some differences between registration systems in their ability to simulate mandibular movements have been reported, but the speed at which this technology is evolving makes scientific analysis difficult 3,34 …”

Setting the Sagittal Condylar Inclination on a Virtual Articulator Using Intraoral Scan of Protrusive Interocclusal Position and Cone Beam Computed Tomography

“…Similar to a traditional mechanical articulator, a virtual articulator is an instrument to reproduce the position of the maxillary and mandibular dental arches, and to simulate the movement of jaw . Recently, many studies on a virtual articulator have been reported; however, most studies include mounting of the maxillary dental arch, or comparing the accuracy of articulation with a traditional mechanical articulator …”

“…The SCI values were measured as 43.50° on the left side and 45.50° on the right side by Christensen's method, and 44.25° on the left side and 46.17° on the right side by this technique. We speculate that the small difference in the SCI value is caused by the facebow transfer procedure and the positioning of the FH plane, than the articulation procedure . Compared to the arbitrary facebow transfer method, the position of the FH plane in this technique is closer to that of the kinematic facebow transfer method, which is a gold standard …”