OBJECTIVE: To assess whether articulating casts in centric relation (CR) compared with intercuspal
position (ICP) makes a difference to treatment planning.
Design: Reliability analysis.
Subjects: Ten orthodontists.
METHODS: Twenty case vignettes were examined on three occasions: twice with the casts in ICP
and once in CR. A series of dichotomous decisions were made relating to the treatment need and
treatment mechanics.
MAIN OUTCOME MEASURES: The changes in treatment decisions were examined. Intra-examiner
agreement between the two hand-held cast assessments (H1 v. H2) and between the first set of
hand-held casts compared with the articulated casts (H1 v. A1) were evaluated using the kappa
statistic. The differences between the kappa statistics for H1 v. H2 and H1 v. A1 were then tested
with the Wilcoxon matched pairs signed rank sum test.
RESULTS: The only statistically significant change in the kappa score between H1 v. H2 and H1 v.
A1 was for the extraction decision (P 0.007). No other statistically significant differences were
found for the other treatment decisions, although trends were identified for orthognathic
surgery and anchorage support decisions.
CONCLUSION: Routine articulation of study models for all orthodontic patients is not supported
by the results of this study. Articulation of the study models did not affect the treatment planning
decisions in a meaningful manner. Further work with selected samples is required to
determine if articulation is helpful for specific malocclusions
