care. Dental patients do not routinely have blood drawn as part of the standard of care.

Also it is important to note that other studies have found that even though the information

provided by patients may not be as accurate as compared to laboratory testing, it is

nevertheless a reliable source of information which can be utilized cost-effectively in

research studies [100, 101].

 The reliability and validity of using IHC analysis is another concern which must be

addressed. Due to the subjective nature of this method there have been suggestions in the

literature for ways in which to standardize this technique. One group has stated that

reliable and precise quantitative IHC requires the use of control materials containing

defined amounts of the target antigen and processed alongside the specimen combined

with automated computer-assisted microspectrophotometry [102]. Use of this modality

was beyond the scope of this investigation.

 Another potential error in this study may be attributable to the subjective nature of

the grading process. Interpretation of immunostains should be based on microanatomic

distribution of the staining, proportion of positively stained cells, staining intensity, if

relevant, and cutoff levels [102]. These parameters should be shown to be reasonably

reproducible and should be clearly defined [102]. This was attempted by using the

grading scale employed from previous investigations [92, 94]. The grading scale utilized

in this study and many others are based on one that was first developed in 1968 [103].

This early grading scale was called the Chisholm-Mason's Scale and it and varying forms

of this scale have been used for multiple IHC studies [92, 94].

 But, due to its subjective nature many critics argue IHC analysis is not fully

reproducible and lacks accuracy and validity. One review of the IHC technique stated that