Comparing maximum intercuspal contacts of virtual dental patients and mounted dental casts.
BACKGROUND
Quantitative measures of occlusal contacts are of paramount importance in the study of chewing dysfunction. A tool is needed to identify and quantify occlusal parameters without occlusal interference caused by the technique of analysis.


OBJECTIVE
This laboratory simulation study compared occlusal contacts constructed from 3-dimensional images of dental casts and interocclusal records with contacts found by use of conventional methods.


METHODS
Dental casts of 10 completely dentate adults were mounted in a semi-adjustable Denar articulator. Maximum intercuspal contacts were marked on the casts using red film. Intercuspal records made with an experimental vinyl polysiloxane impression material recorded maximum intercuspation. Three-dimensional virtual models of the casts and interocclusal records were made using custom software and an optical scanner. Contacts were calculated between virtual casts aligned manually (CM), aligned with interocclusal records scanned seated on the mandibular casts (C1) or scanned independently (C2), and directly from virtual interocclusal records (IR). Sensitivity and specificity calculations used the marked contacts as the standard. Contact parameters were compared between method pairs. Statistical comparisons used analysis of variance and the Tukey-Kramer post hoc test (P=<.05).


RESULTS
Sensitivities (range 0.76-0.89) did not differ significantly among the 4 methods (P=.14); however, specificities (range 0.89-0.98) were significantly lower for IR (P=.0001). Contact parameters of methods CM, C1, and C2 differed significantly from those of method IR (P<.02). The ranking based on method pair comparisons was C2/C1 > CM/C1 = CM/C2 > C2/IR > CM/IR > C1/IR, where ">" means "closer than."


CONCLUSIONS
Within the limits of this study, occlusal contacts calculated from aligned virtual casts accurately reproduce articulator contacts.
Delong
Ralph
R
School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA. delon002@tc.umn.edu
Ko
Ching-Chang
CC
Anderson
Gary C
GC
Hodges
James S
JS
Douglas
W H
WH
D000328:Adult; D000704:Analysis of Variance; D003724:Dental Arch / Q000033:anatomy & histology; D003725:Dental Articulators; D003760:Dental Impression Materials / Q000737:chemistry; D003766:Dental Occlusion; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007574:Jaw Relation Record / Q000295:instrumentation / Q000379:methods*; D008334:Mandible / Q000033:anatomy & histology; D008409:Mastication / Q000502:physiology; D016555:Matched-Pair Analysis; D008437:Maxilla / Q000033:anatomy & histology; D003765:Models, Dental; D011145:Polyvinyls / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012833:Siloxanes / Q000737:chemistry; D012984:Software; D013223:Statistics as Topic; D014070:Tooth / Q000033:anatomy & histology; D014584:User-Computer Interface
D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane