As jaw-tracking systems integrate into digital prosthetic workflows, their accuracy
remains underexplored. This study aimed to evaluate the in vitro accuracy of a novel
digital jaw-tracking system (Modjaw, Villeurbanne, France) by comparing its precision
and trueness to that of an industrial scanner.Upper and lower typodont models were
scanned with an industrial-grade optical scanner (ATOS Q, Carl Zeiss GOM Metrology
GmbH, Germany) to produce master scans. The models were placed in a phantom head with
artificial joints to replicate five different intermaxillary relationships (IMRs).
The 1, 2, 3, 4, and 5 mm IMR distances were stabilized by five silicone bites. The
silicone bites were repositioned after each measurement. ATOS scanned the whole artificial
joint with the models three times in each IMR to assess the precision of the repositioning
(i.e., bite precision). The master scans were uploaded to Modjaw. Modjaw recorded
the five IMR positions three times each to assess the precision of the Modjaw. Precision
was calculated by aligning the scans within the same group, whereas Modjaw trueness
was evaluated by aligning ATOS and Modjaw scans. The mean absolute distance (MAD)
between aligned surfaces was calculated. The effect of IMR on the MAD was evaluated
using a linear mixed model.The mean bite precision across the IMRs was 7.6 ± 0.53
µm. Modjaw precision over the IMRS was 9.7 ± 1.76 µm, and the trueness was 10.8 ±
1.40 µm. Increased IMRs up to 4 mm significantly increased the MAD from 6.5 to 8.5
µm for the bite precision, 4.8 to 15.7 µm Modjaw precision, and 7.1 to 14.9 µm for
trueness.Modjaw excelled in accuracy, comparable to industrial scanners and superior
to traditional methods. IMR elevation marginally deteriorates the accuracy. Future
studies should extend to varied movements beyond centric relations and encompass the
influence of intraoral scanners.
