Does severe crowding always mean that teeth need to be removed? Conversely, is non-extraction orthodontic treatment suitable when the teeth are relatively straight?
The decision to extract teeth is not based solely on how crooked they are. Even with the same degree of crowding, treatment plans differ according to lip prominence, the angle of the front teeth and the relationship between the jaws. Deciding whether non-extraction treatment is suitable means looking beyond whether the teeth can be aligned: we also need to consider whether we can achieve the changes in facial appearance that the patient wants.
<An example of dental crowding>
We look at the facial profile before the alignment of the teeth
<The esthetic line>
When planning treatment, we first examine the shape of the face, particularly its side view, or profile. By looking at the relationship between the nose, lips and chin, we assess how prominent the lips are and how much change is needed. We also refer to the E-line, which connects the tip of the nose to the chin, but no single line or measurement determines whether extractions are necessary.
Even if the teeth are somewhat crooked, non-extraction treatment may be considered if the lips are not very prominent and enough space can be created while maintaining the current facial balance. In particular, when the front teeth tilt too far inward, bringing them to a more appropriate angle can provide some of the space needed. As this can also improve the angle of the front teeth and the smile line, a good result may be possible without extractions.
Conversely, even when the teeth are straight, the front teeth may need to move back considerably to reduce lip prominence sufficiently. If the space available without extractions is not enough to achieve the desired changes, extraction treatment may be more appropriate.
Ultimately, we need to consider not only how many millimeters of space are missing, but also where the front teeth and lips will be positioned once that space has been created.
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<MARPE: a palatal expansion appliance>
In borderline cases, we first consider whether the teeth can be preserved
In borderline cases where either approach could be considered, we first explore non-extraction treatment whenever possible. If we can achieve the desired result while preserving the natural teeth, there is no reason to choose extractions unnecessarily.
However, we should not expand the dental arch excessively or tip the front teeth too far forward simply to avoid extractions. The criteria are whether the teeth can move safely within the supporting bone and whether the required space can be created while achieving both a balanced bite and facial harmony.
The reasons for considering non-extraction treatment differ in growing patients and middle-aged adults
During the growing years, the remaining growth of the jaws and face can be used in treatment, potentially making non-extraction treatment possible in more cases. Even with the same degree of malocclusion, we may first consider non-extraction treatment if we can create the necessary space while making favorable use of the direction of growth. However, the direction and amount of growth differ from patient to patient, so being young alone does not mean that non-extraction treatment is appropriate.
For adults in their 40s and 50s, non-extraction treatment is often advantageous for different reasons. At this stage, we need to consider not only the condition of the gums and supporting bone and the presence of restorations or implants, but also changes in the elasticity and volume of facial soft tissues. In patients with pronounced nasolabial folds or sagging around the mouth, moving the front teeth and lips back a great deal may reduce support around the mouth and make the face appear more sunken in some cases.
Therefore, if the required space can be created within safe limits and the desired result achieved, non-extraction treatment may be a more appropriate choice in middle age, reducing the amount of tooth movement and preserving natural teeth. The decision ultimately depends not on age alone, but on growth potential, periodontal health, changes in facial soft tissues and the goals of treatment.
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| <After non-extraction treatment for crowding> | <After extraction treatment for crowding> |
We also consider whether the result can remain stable
Some patients worry that relapse is more likely after non-extraction treatment. However, it is difficult to judge long-term stability based on extraction status alone. Erdinc and colleagues compared records from 98 patients treated with or without premolar extractions, taken before treatment, after treatment and after the retention period. In the postretention period, irregularity of the lower front teeth increased by 0.97 mm in the extraction group and 0.99 mm in the non-extraction group, with no significant difference between the two groups.[1] This provides evidence that we cannot simply assume the front teeth are more likely to relapse because treatment was performed without extractions.
The first priority is to finish treatment with stable front-tooth positions and a stable bite, without excessive expansion of the dental arch. After treatment, patients should wear their retainers for the amount of time recommended by their orthodontist and attend regular check-ups. Planning for this ongoing retention care is also essential to maintaining the results over the long term.
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| <Before treatment: October 25, 2012> | <After treatment: September 12, 2014> |
When non-extraction orthodontic treatment may be considered
To summarize, non-extraction treatment may be considered when the necessary space can be created safely within the supporting bone and the desired changes to the teeth and face can be achieved without moving the front teeth too far forward. Another requirement is that we can achieve tooth positions and a bite that can remain stable after treatment.
Non-extraction treatment is not appropriate in every case. When these conditions are met, however, it can be a good treatment option that preserves natural teeth while offering the prospect of a satisfying result.
References
[1] Erdinc AE, Nanda RS, Işiksal E. Relapse of anterior crowding in patients treated with extraction and nonextraction of premolars. Am J Orthod Dentofacial Orthop. 2006;129:775–784. View article