  We study quantum loop corrections to two-point functions and extraction of
physical quantities in a five-dimensional $\phi^4$ theory on an orbifold. At
two-loop level, we find that divergence for quartic derivative terms of
$(p^2)^2$ appear as Lagrangian terms in the bulk. The counterterms are needed
and these terms make propagators have two poles. With this effect taken into
account, corrections to masses are derived. We show that for extraction of
physical quantities for two-point functions an ultraviolet cutoff must be
orders of magnitude larger compared to a compactification scale. Even higher
derivative corrections at higher loop levels are also discussed.
