B

Studies that measured the biologic “freedom-in-centric” zone show that the mandible can vary only a few tenths of a millimetre around the centric relation position—mean anteroposterior and mediolateral shifts are about 0.28–0.30 mm, with most subjects remaining within a 0.3–0.4 mm diameter zone [Simon & Nicholls 1980, PMID 6929920; Utz et al. 1990, PMID 2300795]. Hence, freedom of centric relation corresponds best to the 0.20–0.40 mm range.