Facial Soft Tissue Depths in Craniofacial Identification (Part I): An Analytical Review of the Published Adult Data*

Abstract

With the ever increasing production of average soft tissue depth studies, data are becoming increasingly complex, less standardized, and more unwieldy. So far, no overarching review has been attempted to determine: the validity of continued data collection; the usefulness of the existing data subcategorizations; or if a synthesis is possible to produce a manageable soft tissue depth library. While a principal components analysis would provide the best foundation for such an assessment, this type of investigation is not currently possible because of a lack of easily accessible raw data (first, many studies are narrow; second, raw data are infrequently published and/or stored and are not always shared by some authors). This paper provides an alternate means of investigation using an hierarchical approach to review and compare the effects of single variables on published mean values for adults whilst acknowledging measurement errors and within-group variation. The results revealed: (i) no clear secular trends at frequently investigated landmarks; (ii) wide variation in soft tissue depth measures between different measurement techniques irrespective of whether living persons or cadavers were considered; (iii) no clear clustering of non-Caucasoid data far from the Caucasoid means; and (iv) minor differences between males and females. Consequently, the data were pooled across studies using weighted means and standard deviations to cancel out random and opposing study-specific errors, and to produce a single soft tissue depth table with increased sample sizes (e.g., 6786 individuals at pogonion).

Soft tissue thickness values for black and coloured South African children aged 6–13 years

“…As expected, STT at these landmarks was larger in the 13 year old group compared to the 10 year old group. These differences are all less than 3 mm and the practical value of such small differences have been questioned [18,[23][24][25]. In practical terms few significant differences were seen between age groups and the STT increased at only at two landmarks with age.…”

“…CT and MRI values produced the lowest discrepancies [18]. Stephan and Simpson [18] have shown that even though differences in methodology render different values, these values often do not differ significantly in terms of statistical or practical application.…”

“…CT and MRI values produced the lowest discrepancies [18]. Stephan and Simpson [18] have shown that even though differences in methodology render different values, these values often do not differ significantly in terms of statistical or practical application. In a review, they compared a pooled set of STT data from different authors and with different methods, such as needle puncture, ultrasound, cephalograms, CT and MRI, to ascertain practical differences.…”

“…In terms of ultrasound, an experienced ultrasonographer or radiologist is required and children may not be as compliant as adults [17][18][19]. It is also time consuming, as it needs to be ascertained that there is no compression of the soft tissue overlying the bony landmark which can cause inaccurate measurements.…”

“…They concluded that, regardless of the strengths and weaknesses of each method, one method was not superior to the other. They suggested that STT data be pooled without considering the different methodologies [18,[23][24][25]. Recent studies favored either ultrasound [16] or CT [20,21].…”