Single-Phase Versus Two-Phase Orthodontics – Who and Why?

It is recommended that some patients receive their orthodontic treatment over the course of two phases while other patients receive their treatment in a single phase - what’s the difference?

Two-phase-treatment means that a patient is prescribed an early treatment in the mixed dentition (both baby teeth and permanent teeth are present) to address some type of severity relative to their malocclusion that is not always but often skeletal in nature. Examples of these types of treatment may be an expander to widen the upper jaw if it is narrow/constricted relative to its lower counterpart and crossbites are present or, some form of growth modification used to improve the relationships between the jaws when for instance the lower jaw is significantly recessive/short relative to the upper jaw and there is a large overjet (horizontal distance between upper front teeth and lower front teeth).

Side profile of girl before orthodontic treatment

Before Treatment

Side profile of girl after orthodontic treatment

After Treatment

Later, when the permanent dentition is complete a second-phase of orthodontics is completed to detail the alignment of the teeth and fit of the bite.

Patients who are recommended that treatment be completed in a single-phase are generally less severe cases and treatment is not commenced until the permanent dentition is complete or nearing completion.

In general, phase I treatments involve skeletal corrections that are more gross/general in nature and phase II treatments involve dental corrections that are more detailed.

In this article, I will show a patient from my practice that received two-phase treatment. Her first phase of treatment involved growth modification to correct her recessive lower jaw, large overjet (10-11mm) and deep tissue impinging overbite (vertical distance upper front teeth cover the lower front teeth). This treatment was achieved by having the patient wear a removable lower jaw repositioning device 12 hours/day during non-school hours (after school and over-night). This treatment extended 15 months. The outcome was that the patient has a straighter or more balanced profile (improved relationship between the upper and lower jaws), the overjet was reduced from 10-11mm to 1-2mm and the overbite was reduced from 100% to 10% (ideal is 30% but the case was purposefully over-corrected).

The second phase of treatment involved full braces to straighten the individual teeth, close any spaces and fit the bite like puzzle pieces in order to achieve the most ideal and stable finish. This treatment was achieved with braces on all of the teeth (including permanent second molars) and with the use of intraoral elastics. This treatment also extended 15 months and was completed with a combination of fixed (bonded wires) and removable retention.

If you are seeking a smile like this for your son/daughter, please call our office to book your free exam today!

About the Author

Dr. Virginia Luks

Dr. Virginia Luks wanted to be an orthodontist like her father since she was a child. In 1997, after extensive training and accreditation, she joined her father's practice at Luks Orthodontics. She became one of the youngest orthodontists to attain Diplomate status in the American Board of Orthodontics and the first woman to be elected to Ontario's Dental Licensing Board, the Royal College of Dental Surgeons of Ontario. Dr. Luks thrives on clinical practice and creating new smiles every day. So for over twenty years, that’s what you’ll find her doing.

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