FAQ: “What are the indications for pre-adolescent “Phase 1” orthodontic treatment ?” Part 1 – Crossbite | [NOA Dr Nagy Post:#04022021]
This is a pretty large topic with many details, so I’ll address it over a couple of posts. I recently taught a course to orthodontic residents and GPs regarding this topic, so I thought I’d share some posts with the hope that they may help some of you struggling with this very common question.
Phase 1 orthodontic treatment is not always indicated; however, there are several different reasons for “Phase 1” treatment.
This week we will focus on the first major reason: #1. Crossbite.
What is a Crossbite? When teeth are lined up properly, the maxillary teeth are naturally wider because they are positioned on the outside of the mandibular teeth. (see pic #1) A crossbite is a misalignment of teeth (malocclusion), where the maxillary teeth are positioned inside of the mandibular teeth. This crossbite can affect anterior or posterior teeth or both; it can also affect a single tooth or groups of teeth.
- Posterior crossbite: The back teeth are affected, ie maxillary teeth sit lingual to mandibular teeth.
- Anterior crossbite: The front teeth are in crossbite, ie one or more maxillary teeth are positioned behind the mandibular teeth. (Do not confuse this with a class III underbite, in which case all the maxillary teeth, or the jaw itself, are behind the mandibular teeth.)
What is a Crossbite? cont’d:
In some cases the posterior crossbite can be less obvious and can be hidden by the lingually tipped (compensated) lower posterior molars, so a proper arch analysis is a must in every case. Don’t always just believe your eyes when you look at a case. (see NOA pic#2)
Posterior crossbite at an early age (age 6-8) can result in several issues, such as functional shift, which can also give rise to TMJ issues such as condylar and disk development and proper functional TMJ development.
So, it is important to correct a posterior crossbite early when it develops.
The preferred time to correct this posterior crossbite, is around age 7-8 when the permanent molars are fully developed, but before the maxillary mid-palatal suture starts to mature, and at the time when the patient is emotionally mature to go through phase 1 orthodontic treatment. (See example case pic #3-4)
How do we treat a crossbite?: With a rapid palatal expander to open the maxillary mid-palatal suture. (see NOA pic#5)
Next week we will continue this topic of “FAQ: ‘What are the indications for pre-adolescent Phase 1 orthodontic treatment?’”
If you have any questions, comments, and/or suggestions for topics of future posts, please feel free to comment below.
Thank you, and have a great week.
Dr Attila Nagy DDS MSMaster of Science in Specialized Orthodontics
General Practice Dentist
*(Note: these slides are from the NOA Comprehensive Online Orthodontic Mini Residency)
*Edited by Dr. Michelle C Nagy DDS