Is there a sexual dimorphism in Wormian bones presence? A study on Polish and Lithuanian sample.

Background: Wormian bones (WB) originate from accessory ossification centers and occurr irregularly within cranial sutures. They are common, however some authors claim that in particular cases WB may reflect the developmental instability. Since males are more susceptible to environmental disturbances (which can lead to developmental instability), it is crucial to establish the possible discrepancy in WB appearance among sexes. The aim of study was to examine the sexual differences in WB presence.

Materials and methods: 317 adult skeletons from Polish and Lithuanian series: Ostrów Lednicki (185: 135 males and 50 females), Bokštro gatve 6 (69: 42 males and 27 females), and Subačiaus gatve 7 (63: 44 males and 19 females) were selected. Number of WB was noted, and their diameters were measured. In the Lithuanian sample the area of single WB's was measured photogrammetrically. Statistical calculations were performed with the significance defined as p < 0.05.

Results: Among Polish sample 117/135 (86.7%) of males and 35/50 (70%) of females represented at least one WB. In the Lithuanian sample it was 65/86 (75.6%) and 28/46 (60.9%), respectively. Difference was significant in Polish (p = 0.009) sample. The sexual difference of WB number was significant (p = 0.01 for Polish and p = 0.02 for Lithuanian sample).

Conclusions: The sexual dimorphism of appearance and number of WB has been confirmed. WB are observed in greater numbers in males, but sexual differences are rarely analyzed statistically. There is a need for further work on sexual dimorphism of WB, especially in non-Asian populations.