Dear Sir, taking into consideration the malalignment problem that your son is facing I would strongly recommend that you take him for a consult to an Orthodontist ideally. The Orthodontist will evaluate if the condition is only a Dental problem or combined with a Skeletal issue. But coming back to your question of making a choice between a Pedodontist/Paediatrician - given its a dental problem, a Pedodontist makes a much better pick.
Next Steps
Consult an ORTHODONTIST
Health Tips
Take an OPG of your son alongwith you for the consult.