To broaden perspective this question can be rephrased as: What is the limit of Midfacial expansion to be further coordinated in a functional bite? and what are the optiosn for the lower arch to fit the expanded upper arch?
We will start with evaluation of the baseline data:
- the initial malocclusion
- facial structure
- amount of facial transformation one is planning on
- presence of implants/ restorations on both arches
- amount of initial lower molar inclination
- potential or initial planning of surgical jaw advancement /maxillary and mandibular/
1. Initial malocclusion may or may not present itself with the crossbite.
The posterior crossbite can be bilateral or unilateral. In a case like this, the primary goal is to correct the existing crossbite. But this may not be the only indication for the midfacial expansion in this situation. Furtehr bone disarticulation may be granted to correct mandibular misalignment, residual midline discrepancy, facial underdevelopment, need for desired facial changes. To e a little more precise, The average skeletal crossbite requires non more than 2-3 mm or midpalatal disarticulation.
2. Facial structure. Even in the absence of any posterior crossbite, 3D guided midpalatal piezocorticotomy assisted MARPE or FME expansion produces beneficial face changes.
The amount of expansion depends on the initial facial structure and desired changes. In our practice we have successfully accomplished midpalatal disarticulation in the amount of 12 mm. The average case of adult female expansion in the practice is 5-6 mm, while adult male patients reach amounts of 7-8-9 mm of midpalatal disarticulation on average.
3. Implants on the upper arch require certain additional changes to the treatment planning in case the body of the implant is desired to be kept.
The cap of the implant (crown) might need to be replaced at the end of the treatment.
4. Implant on the lower arch are slightly difficult to manage due to additional requirement of replacing the crown-keeping part (abutment) and the crown covering implant (the cap).
5. The MARPEFACE protocol is the unique combination of the technique focused on lower arch remodeling , most of the times, selective remodeling. this is associated with changes in mandibular posterior teeth inclinations, their bodily movemtn and bone remodeling. In our experience. this approach has successfully added up to 6 mm of base width to the lower arch. All lower arch movements (as well as upper arch tooth movements) are accomplished with aligners. We were able to receive better outcomes with Direct Printed Aligners (Shape Memory Aligners, Graphy, Seoul, Korea) compared to regular thermoformed aligners.
6. Surgical planning for the lower jaw (if any) is usually discussed during the initial consultation with the patients is not something that may appears as a suprise later on during the treatment. Treatment planning is a precise process involving individual planning of tooth movements for every patient and differs significantly depending on the initial malocclusion.
Dr.Svitlana Koval and her team plan every case individually and are able to make this process as smooth as possible and as efficient as it could be.