Digital workflow for a dental prosthesis that considers lateral mandibular relation

Three-dimensional analysis of the outcome of different scanning strategies in virtual interocclusal registration

PURPOSE

The purpose of this in vitro study was to assess whether scanning strategies of virtual interocclusal record (VIR) affect the accuracy of VIR during intraoral scanning.

MATERIALS AND METHODS

Five pairs of reference cubes were added to the digital upper and lower dentitions of a volunteer, which were printed into resin casts. Subsequently, the resin casts were articulated in the maximal intercuspal position in a mechanical articulator and scanned with an industrial computed tomography system, of which the VIR was served as a reference VIR. The investigated VIR of the upper and lower jaws of the resin master cast were recorded with an intraoral scanner according to 9 designed scanning strategies. Then, the deviation between the investigated VIRs and reference VIR were analyzed, which were measured by the deviation of the distances of six selected reference points on the upper reference cubes in each digital cast to the XY-plane between the investigated VIRs and reference VIR.

RESULTS

For the deviation in the right posterior dentitions, RP group (only scanning of right posterior dentitions) showed the smallest deviation. Besides, BP group (scanning of bilateral posterior dentitions) showed the smallest deviation in the left posterior dentitions. Moreover, LP group (scanning of left posterior dentitions) showed the smallest deviation in the anterior dentitions. For the deviation of full dental arches, BP group showed the smallest deviation.

CONCLUSION

Different scanning strategies of VIR can influence the accuracy of alignment of virtual dental casts. Appropriate scanning strategies of VIR should be selected for different regions of interest and edentulous situations.

Prediction of learning curves of 2 dental CAD software programs, part 2: Differences in learning effects by type of dental personnel

STATEMENT OF PROBLEM

Dental computer-aided design (CAD) software programs are essential elements of the digital workflow. Therefore, it is necessary to study the learning effect of dental CAD software programs for efficient use.

PURPOSE

The purpose of this in vitro study was to predict the learning curve of dental CAD software programs according to dental personnel by using the Wright model and to investigate the tendency of dental personnel to reduce working time according to repeated learning.

MATERIAL AND METHODS

A total of 36 participants were recruited, including an equal number of dentists, dental technicians, and dental students (12 each). A custom abutment design was evaluated by using exocad CAD and Deltanine CAD software programs. The design was carried out in the following order: 4 steps repeated 3 times each. This study applied the formula of the Wright model to predict 500 repetitive times. In the statistical analysis, 3-repetition and 500-repetition times were analyzed with the Kruskal-Wallis H test and Friedman test (α=.05), and a post hoc comparison was performed by using the Mann-Whitney U-test and Bonferroni correction method (α=.017).

RESULTS

Three repetitions resulted in shorter working time in the dental technician group. The 3-repetition time decreased statistically for all dental personnel (P<.001). The time for 500 repetitions showed a statistically significant difference according to the type of dental personnel (P=.036), but no significant difference was found after the fourth iteration (fifth iteration: P=.076). Furthermore, the estimated time of 500 iterations decreased statistically significantly from the first to the 500th iteration (P<.001).

CONCLUSIONS

All dental personnel showed learning effects of dental CAD software programs. Although the dental technician group initially showed less working time, after initial learning, the same learning effect appeared, regardless of the type of dental personnel.