The incidence of asymmetrical left/right skeletal and dental development in an Australian population and the effect of this on forensic age estimations

Abstract

The prevalence of developmental asymmetry between left and right sides of the body in the third molar tooth and medial clavicular epiphysis is examined in a contemporary Australian population (92% Caucasian). The contention that differences between left and right side developmental timing is statistically insignificant, and can therefore be ignored in forensic age estimation procedures, is questioned. It was found that of a population sample of 604 individuals, 177 displayed asymmetrical timing in development between antimeres of the third molar, the medial clavicle or both. There was no correlation found between the third molar tooth and medial clavicular epiphysis in terms of left/right synchronicity. For those individuals differing in development by two or more developmental stages in either age marker or one stage in both age markers, the effect upon the accuracy of forensic age estimations can be significant. Differences in age estimates for each side were as much as 3.1 years. Age estimations based on one side only may not provide the best estimate for an individual, and more accurate results can be achieved if both sides are taken into consideration. A protocol for dealing with asymmetrical development is discussed with reference to the multifactorial age estimation method proposed by the same authors in previous research.

Staging Clavicular Development on MRI: Pitfalls and Suggestions for Age Estimation

“…Still, since both are scanned simultaneously and morphological variants may occur unilaterally, the authors suggest the inclusion of both in the MRI scan. This complies with earlier suggestions . Moreover, when stages 1 and 4/5 are discarded, combining both clavicles increases the specificity (+7.4% right; +5.6% left).…”

“…As a consequence of including advanced substages of stage 3a, asymmetry was more prevalent in the current study population (51%; 230/449) than in the literature. MRI studies reported a prevalence ranging from 9% (19/220) to 16.4% (37/225), while in CT studies the range was 6% (18/300) to 18% (108/604) . However, none of those studies applied advanced substages of stage 3a.…”

“…This complies with earlier suggestions. 2,4,27,28 Moreover, when stages 1 and 4/5 are discarded, combining both clavicles increases the specificity (+7.4% right; +5.6% left).…”

“…MRI studies reported a prevalence ranging from 9% (19/220) 4 to 16.4% (37/225), 7 while in CT studies the range was 6% (18/300) 26 to 18% (108/604). 27 However, none of those studies applied advanced substages of stage 3a. Moreover, it was noted that the left clavicle was more often clearly depicted than the right in the current population.…”

Comparison of the third molar maturity index (I3M) between left and right lower third molars to assess the age of majority: a multi-ethnic study sample

“…Although these differences are not observed in the values of medians and values of first and third quartiles, they reflect those cases in which the lower third molars' development does not occur in a similar way in the same age range of the same population. These results are in agreement with the concept of "fluctuating asymmetry" proposed by Bassed et al [63]. They stated that when all of the identified asymmetric cases are assessed separately (i.e.…”