Thank you for your question and for sending photos of your lovely little girl. From her profile photo, it does appear that her lower lip is slightly more in front of her upper lip and the lower jaw is also slightly more prominent on her frontal photo.
You mentioned that she has an underbite, meaning that her lower teeth bite in front of her upper teeth, this is not apparent in the photos you sent as she didn't show any teeth so it is hard for me to determine that.
These are some of my considerations in deciding early treatment (5-10 years old) vs treatment later for her.
1. Family history: do other family members also present with a longer lower jaw and an underbite and how severe is the presentation?
2. Number of teeth present in the mouth to hold the appliance. At 5 years old, she may not have enough teeth to secure the braces appliance that we will use to correct her underbite. We may also want to wait for her adult front teeth to erupt so that those teeth can be the reference to how much of the underbite I would want to correct.
3.Maturity and treatment acceptance of the child. Early treatment using facemask protraction to correct the underbite requires compliance from the child and it is best if the child is motivated and wants to undergo the treatment otherwise it may be an uphill battle getting the child to wear the appliance. If the child is not motivated now, she may be in a few years time and she is still within the age range for early treatment.
4. The severity of the underbite, the number of teeth involved with the underbite and the amount of overlap between the upper and lower front teeth.The severity of the underbite will help determine if an early correction will be feasible or if later treatment may be more beneficial. This is best determined with an oral examination, your dentist may ask her if she can bite her front teeth on the edge so as to assess how severe is the underbite.
Early treatment of an underbite is most beneficial if what I want to achieve is to protract or bring the upper jaw forwards especially if the upper jaw is relatively more set back compared to the lower jaw. This is because the joints holding the upper jaw, what is known as sutures are still soft and pliable and can be modified at a younger age. As the child grows, these sutures become more mature and harder to influence.
Hope this helps and all the very best,
Dr Priscilla Lu
Orthodontist
