skeletal Hyperdivergency in mixed dentition, part a
Dr. Michel Champagne, BA, DMD, MAGD, IBO, CDE
We could classify hyperdivergency in 2 types. One which is acquired without any cranio-mandibular deficiency (anterior open bite cases with a light skeletal open bite associated to a thumb sucking habit). The other is a skeletal open bite coupled to a craniofacial dysmorphosis showing an excessive lower anterior face height often associated with a lip seal problem.
The craniofacial dysmorphosis ia caused by a lack of growth coordination between the condyle-glenoid fossa (horizontal factor) and the alveolar process (vertical factor). This excessive expression of the vertical factors over the horizontal ones results in a clockwise mandibular rotation opening the way to an anterior skeletal open bite. The treatment options may vary depending on the age of the subject, you may have to choose between an early treatment or a later one. In this summarized text, we will discuss in part the mixed dentition approach and leave the rest for the next blogs.
Even as early as 1986, doctors Linder-Aronson and Woodside suggested the treatment of this dysmorphosis using an extra-oral approach (high pull headgear night time wear) for a minimum of 12 months (Image 1) or a spring loaded removable posterior intrusion appliance that I will discuss in the next parution. Even if the extra-oral approaches proved it’s efficacy, most of the clinicians are reluctant to use it because of a lack of cooperation. There are other options that we will discuss in more details in the coming months but all approaches need an adequate airway. The patient must breathe and swallow normally, it is the key to success whatever technique you will choose.
For the anterior open bite resulting from a thumb sucking habit, you may choose a tongue trap (image 2) or tongue prongs (Images 3-4) and it may suffice. If we want to maximise our success rate, we have to find the cause of the sucking habit and often this is more of the domain of psychology than the dental one. We need a team approach and the patient must shows a desire to stop, if we want to be successful.
Image 1. High pull headgear
Image 2. Tongue trap.
Image 3. Tongue prongs on bands
Image 4. Bonded tongue prongs