An In-Vitro Evaluation of Articulation Accuracy for Digitally Milled Models vs. Conventional Gypsum Casts

Abstract

With the advent of a digital workflow in dentistry, the inter-occlusal articulation of digital models is now possible through various means. The Cadent iTero intraoral scanner uses a buccal scan in maximum intercuspation to record the maxillomandibular relationship. This in-vitro study compares the occlusion derived from conventionally articulated stone casts versus that of digitally articulated quadrant milled models. Thirty sets of stone casts poured from full arch polyvinyl siloxane impressions (Group A) and thirty sets of polyurethane quadrant models milled from digital impressions (Group B) were used for this study. The full arch stone casts were hand-articulated and mounted on semi-adjustable articulators, while the digitally derived models were pre-mounted from the milling center based on the data obtained from the buccal scanning procedure. A T-scan sensor was used to obtain a bite registration from each set of models in both groups. The T-scan data derived from groups A and B were compared to that from the master model to evaluate the reproducibility of the occlusion in the two groups. A statistically significant difference of the contact region surface area was found on #11 of the digitally articulated models compared to the master. An analysis of the force distribution also showed a tendency for a heavier distribution on the more anterior #11 tooth for the digitally articulated models. Within the limitations of this study, the use of a digitally articulated quadrant model system may result in a loss of accuracy, in terms of occlusion, the further anteriorly the tooth to be restored is located. Care must be taken to consider the sources of inaccuracies in the digital workflow to minimize them for a more efficient and effective restorative process.

Conventional Dental Impressions vs. Impressions Reinforced with Rigid Mouthguards

“…Lee et al observed that digitalization improves the quality of patients' experience and eases the work of dentists during the treatment [53]. However, the accuracy of digital impressions is not better than that of conventional ones [54,55].…”

A comprehensive review and update on the current state of computer-assisted rehabilitation in implant dentistry

“…68 A key step in the virtual mounting process is accurate recording of the maxillomandibular relationship either directly using an IOS or indirectly by taking conventional impressions, mounting the physical casts onto an articulator and digitising the occlusion. The direct intraoral digitisation of the occlusion has been shown to be as accurate as the indirect method 69,70 but its deviation can be influenced by the amount of pressure the patient exerts when in intercuspal position, 71 the location of teeth and the width of the area scanned, 72,73 the available interocclusal space 74 and the bilateral or unilateral acquisition. 75 conclusion Digital dental implant rehabilitation workflows consist of several steps with varying degree of difficulty.…”

Conventional and digital record maxillary occlusal for the manufacture of complete-arch implant-supported fixed protheses: controlled and randomized clinical trial

“…Maruyama et al (2006) [16] showed that digital articulation methods created more exact contact points during excursive movements. However, Lee et al (2022) [17] reported that digitally articulated milled casts compared to conventionally articulated casts may result in loss of precision regarding occlusion. Porter et al (2018) [18] observed that for accuracy there was an increase in the values of real contact areas and a decrease in close contacts, while for precision, the values of real contact areas and close contact showed the inability of the digitally articulated model to produce uniform occlusal contact points.…”

“…Porter et al (2018) [18] observed that for accuracy there was an increase in the values of real contact areas and a decrease in close contacts, while for precision, the values of real contact areas and close contact showed the inability of the digitally articulated model to produce uniform occlusal contact points. However, these studies were in vitro in situations of complete dentition [15,18] and single crown [16,17].…”