Aim: The goal of the present study was to determine both distances and spatial relationships between centric relation (CR) and maximal intercuspal position (MIP) in the condylar area, and to demonstrate their implications for dental practice.
Keywords: static occlusion, maximal intercuspal position, centric relation, reproducibility, condylar position indicator device, temporomandibular joint compression, temporomandibular joint distraction, freedom in centric relation
Materials and methods: Eighty-one subjects were assigned to one of four licensed dentists, who recorded their CR by six different checkbite registration methods. Maxillary casts were mounted after transferring the individual hinge axes to Dentatus articulators by facebow transfer, and mandibular casts were mounted in precise alignment with the apex of a Gothic arch tracing. A fifth colleague took measurements in the condylar area after transferring the casts to a special measuring articulator. Distances and spatial relationships were calculated as the means of triplicate measurements with casts mounted in CR and of duplicate measurements with casts articulated in MIP for each bite registration method.
Results: Overall, the spatial mean distance between CR and MIP for all methods combined was 0.86 ± 0.52 mm (min 0.05 mm; max 3.14 mm). The corresponding mean distance was 0.47 mm on the purely sagittal plane. The mean position of the condyles in CR was only slightly dorsal and cranial to that in MIP but with considerable variation in all spatial directions.
Conclusions: MIP moves the condyles out of CR to a position that deviates from CR by an average of 0.8 to 0.9 mm spatially and by approximately 0.5 mm on the sagittal plane, with slightly anterior and caudal deviation as well. Hence, the spatial position of the condyles in MIP varies considerably from that in CR. This has substantial implications for dental practice, eg, when performing terminal molar tooth preparation or interpreting condylar position indicator device readings.