Treatment of skeletal Hyperdivergency in mixed dentition, part B
Dr. Michel Champagne, BA, DMD, MAGD, IBO, CDE
Like we mentioned in our last bog last (October Part A), there are 2 types of hyperdivergency, one which is acquired without any cranio-mandibular deficiency (like an anterior open bite with a slightly open skeletal pattern due to a finger sucking habit) and the other, an hyperdivergency secondary to a cranio-facial dysmorphosis with a lack of passive lip seal and supra eruption of the posterior segments. If the patient has acquired a good breathing pattern and an adequate swallowing, it is possible to look at some treatment options to treat the hyperdivergency patient:
–Option A : the use of a silicone occlusal biscuit like the ones used to minimise the stress during debonding (Image 1) and the placement of a molar to molar space maintainer (Image 2). The occlusal biscuit is used as an exerciser to produce molar intrusion or restriction of extrusion. The patient must do series of exercises morning and night, biting on the biscuit. We suggest 3 series of 20 repetitions, biting down for 10 seconds and then relaxing for 10 seconds, 2 times a day. The molar to molar lower space maintainer acts as a restrictor of molar eruption. We can combine this with swallowing exercises and a face former to increase lip seal (go back to the September issue for more details).
–Option B : the use of an active spring posterior bite block appliance (Image 3). This appliance must be used during non social hours and serves the following purposes: normalisation of an anterior open bite, prevention of an increase in the anterior open bite by reducing a clockwise mandibular rotation (down and back). We must evaluate also the disadvantages of wearing such an appliance like a worsen open bite while the appliance is in the mouth. This is the reason why this appliance is worned only during non social hours. Parents-patient cooperation is a must and they must be warned to use the appliance with care to avoid metal fatigue and appliance breakage (AJODFO 2011;140:115-20).
Following the October infoletter, Dr. Arian Palencar (Thorold Ontario) was kind enough to remind me to insist on the fact that any myofunctional exercise must be done on a long period of time (12 to 24 months) to show some results. Present it like sport training…to perform people have to practice. Sometimes a patient will present a posterior occlusal cross bite that we will have to address first, even if this correction will probably worsen the anterior open bite. For a young patient with an excessive hyperdivergency and a posterior cross bite, I would choose without hesitation a fixed rapid palatal expander with high extra-oral traction, night time wear, and then follow with a removable posterior spring activated intrusive appliance.
The mixed dentition treatment necessitates highly motivated team consisting of the parents, the patient and the dental team. If this cooperation is absent, I would not engage into a treatment. It is the dentist duty to describe and explain the treatment options mentioning advantages and disadvantages but leaving the decision of treatment to them. On your part, it is your decision to decide if you want to treat such a case or to refer.
In our next info-letters, we will discuss other therapies for different age groups but we must be aware that when treating hyperdivergent patients we may encounter many obstacles, more than any other malocclusion.
Image 1. Silicone occlusal waiver.
Image 2. Lower molar to molar space maintainer
Image 3. Spring loaded posterior upper molar intrusion appliance