It has been claimed that permanent dental implants improve the well-being o
f patients distressed by their removable dentures. Research appears to sugg
est that this improvement is temporary but the findings have been obscured
by the use of inappropriate measures of distress, failure to control for Ty
pe II and tin ubiquitous use of repeated pair-wise testing) Type I statisti
cal error, poor measures of dental functioning, inadequate descriptions of
sampling, failure to include moderating variables such as the impact of den
tures on daily living and failure to allow for causal effects of distress.
Individual variation has been overlooked: only some patients may be signifi
cantly distressed by their dentures. It has been difficult to find control
groups of patients to exclude the effect of confounding influences. The cru
cial assumption, that psychological distress reduces as dental functioning
improves, has not been examined. Statistical modelling, using suitable meas
ures of chronic distress, controlling for the effects of moderating variabl
es and examining causal relationships, would help to clarify this, Psycholo
gical distress, according to statistical analysis designed to avoid Type I
and Type II error, should be less, long after the fitting of implants than
before.