2.2 How to Differentiate a Child Human Skull from an Adult's??

As professional dental investigators, we shall look into every detail deeply in this case!

According to Dr Rudi, there is at least one male skeleton and perhaps a child one. However, a doubt came into our mind. Can we identify the sex of a child human skull. The answer is definitely NO! It is almost impossible to identify the sex of child human skull as they have not reached puberty yet. Plus, some of the characteristics appropriate to sex have not yet to be shown due to the unreached puberty stage. 

Hmm..(Sip some coffee to get the brain juices flowing). How about the way to differentiate child and adult human skull? Undoubtedly, the child human skull definitely smaller than the adult's. Another great point worth highlighting is that the sutures of the skull play significant role in identifying the age of a child human skull. 

Unknown to many, the frontal suture is a dense connective tissue structure that divides the two halves of the frontal bone of the skull in infants and children. It usually disappears by the age of six, with the two halves of the frontal bone being fused together. It is also called as metopic suture. So, that means if we find metopic suture of the child human skull, we can say that the child is under six years old. Furthermore, the more 'filled-in' the sutures, the elder age is the skull. 

Reference: http://upload.wikimedia.org/wikipedia/commons/d/d1/Frontal_suture.png

Reference: http://www.health-pictures.com/coronal-suture.htm

So beside the small size and sutures of the skull, how else did we manage to determine that the skull is actually from a child? Let me give you a hint: it has something to do with us, the DENTAL INVESTIGATORS!

Bingo! Yup, it is the teeth. But not just any part of the teeth, it's from the tooth eruption dates!

As a baby grows up, teeth start to erupt from the gingiva (aka gums). At first, the baby will have the primary or deciduous dentition which will later shed and replaced by the permanent dentition.
So what is it about the tooth eruption dates?
Unlike what we normally thought it would be, teeth do not shed and erupt randomly but instead follows a chronological order. In other words, the shedding and eruption of each tooth actually takes place in its own respective time frame, at a certain age.

The pictures below shows:

i. The primary/deciduous dentition and the eruption and shedding date of each tooth.( A total of 20 teeth )





ii. The permanent dentition and the eruption date of each tooth.( A total of 32 teeth )



 Picture adapted from: http://www.mouthhealthy.org/en/az-topics/e/eruption-charts

As you can see from the charts and video, there is an overlapping period between the primary and permanent dentition which we would like to call it as mixed dentition period. This simply means the period where the child has some teeth from both the primary and permanent dentition.

Now, too many numbers to digest? No worries,take your time in memorizing the dates as no dental investigator is made in one day. To aid in your understandings regarding this topic, we have prepared a few pictures below.


1.  
This skull contains 12 teeth in both the upper and lower jaws. All of the fully erupted teeth are deciduous. Age assessment would be enhanced with radiographs and CT scans, but the evaluation of the skull alone places the age at 15 to 16 months.  It is not currently possible to reliably determine sex or major racial group with child remains.


2.  
This specimen reveal the underlying dentition in this 5-6 years old. The cortical bone overlying the buccal aspect of the left maxilla and left mandible has been dissected away.  


3.  
The right side of the maxilla and jaw bone has been cut away to show an excellent example of the process of the adult teeth descending while the baby teeth are still in place (Mixed dentition).  Two of the teeth are only visible after part of the mandibular cortical bone has been removed. All available evidence suggests an age of 11 to 13 years.



4. 
This skull offers an excellent example of an adolescent. With the exception of the wisdom teeth, all permanent teeth are fully erupted, and no deciduous dentition remains. The apices of the canines, premolars, and second molars are approximately one-half to two-thirds closed radiographically; this is consistent with 13.5 - 14 years. The crowns of the three remaining third molars are in an early stage of calcification. Radiographically, there is no evidence of root formation. The early stage of third molar crown formation is usually complete by 13 years.

Pictures adapted from: www.boneclones.com

That's it for tooth eruption and do have fun memorizing the dates :)

Reference list:

1)http://en.wikipedia.org/wiki/Starchild_skull
2）http://www.spoilheap.co.uk/hsr1.htm
3）www.boneclones.com
4)http://www.youtube.com/watch?v=ZdglZymoIyQ