Two subject groups had their mandibular positions determined, using an elec
trognathograph, at the clinical rest position (CRP) and at the closest spea
king position (CSP). They were classified into a toothwear (largely of attr
itional origin) group (n = 30) and a non-toothwear, or normal, group (n = 6
0). The mean CRP deduced for the groups was similar in all three dimensions
and found to be just less than 2 mm open from and 0.6 mm posterior to inte
rcuspal position (IP) and approximately in the midline. The CSP, in two dim
ensions, of the toothwear group was significantly closer to IP than that of
the normal group. The vertical component of CRP and CSP was similar for th
e normal group but CSP was significantly reduced in comparison to CRP for t
he toothwear group. The most forward component of CSP was significantly mor
e anteriorly placed than was that of CRP. Although there was a pronounced i
nter-individual variation the results suggest toothwear, of long acting aet
iology, has less affect on CRP than on CSP.