Fixed retainers

January 10, 2023by Mahesh Patel

Almost all orthodontic corrections need retainers. ‘Retainer’ means ‘to keep’ and in terms of orthodontics it is to keep in position the new perfect alignment of the teeth.

So, why do we need retainers?

Teeth move after brace removal because of:

  1. Relapse: these are changes where teeth move back towards their original positions – almost as though the teeth have a ‘memory’. This is due to the elasticity of the gums pulling them towards the original positions.
  2. Biological form: E.g. Strong muscle in the lower lip, lip tone, wisdom teeth, tongue function, digit habits, lip trapping.
  3. Biological development: These changes are ongoing through one’s life-time and largely not predictable. E.g. arch form changes, growth of the jaws.

How are teeth kept straight?

Teeth can be kept straight with retainers. There are two main types and then less common ones:

  1. Fixed retainers – these are fitted to the back of the front teeth.  They are very thin, easy to keep clean and of course cannot be worn incorrectly, forgotten or lost. They feel as natural as you own teeth. If one was keen to keen the teeth perfect the fixed retainer could be a better option.
  2. Removable retainers: There are vacuum formed retainers and acrylic retainers – VFR are thin and ‘glove’ the teeth like cling film – but much thicker. Acrylic are very rigid and excellent to maintain arch form changes. Removable retainers can only be worn part time. As a result, small changes to the teeth are to be expected.
  3. Functional retainers – used in interceptive functional appliances cases (insert link)
  4. Space maintainers – used to keep spaces or arch form. These will retainer occlusal and arch integrity either for late developing teeth to erupt into the gaps or for future implant placement when orthodontics cannot close the gaps.
  5. Specific cosmetic – Transient aesthetic retainers for missing teeth e.g. etch bridges. (insert link)

Which are better?

It depends, as there are a few. For definitive treatment, fixed retainers are better. They are ‘invisible’, comfortable to wear and cannot be forgotten to be worn.

Each patient has individual needs and FIRST Ortho would advise according to needs. For fixed retainers, the key factors to its provision is good oral health and absence of a deepbite.  This ensures good longevity and easy maintenance.

The front teeth are more prone to relapse so fixed retainers are more effective for the front teeth.  Removable retainers useful for arch form maintenance, useful as a ‘re-aligner’, as a bite guard, whitening tray and desensitising teeth which are sensitive. For these reasons, most of our clients have both.

Are FIRST Ortho fixed retainers different?

Yes. It will be hard for you to see a similar example of craftsmanship elsewhere with fellow professionals recognising its near perfect nature:

  1. Our retainers extend over eight teeth. This compares to the average of 6,4 and only 2 teeth. This gives far better stability.
  2. Each pad is like a veneer and feels like your natural teeth making it easier to keep clean.
  3. It is placed away from the gums as we reduce a deepbite to make this possible. This makes gum health easier to maintain.

What else can be done with  fixed retainers?

  1. As the teeth will be more stable, one can aim for a more perfect result in the knowledge the changes will remain.
  2. Improvement in gum health as small spaces (dark triangles)  between the teeth can be closed.
  3. The tips of the teeth can be build as a part of the retainer improving the appearance of the teeth.
  4. Thin edges of the teeth due to bruxism and wear and tear can be reinforced as part of the retainer.
  5. Erosion of the back of the teeth can be protected as we cover the teeth with a thin veneer. However, one will also need to address the initial cause of the erosion.

Examples: Click image to enlarge

Do fixed retainers need replacing?

Fixed retainer: this is hardly replaced at FIRST Ortho. Since 1988, we have advised replaced 6 and on advice removed 19. Considering we fit 5-9 a week, this is a small fraction. The low failure rate is we are selective in patient choice. We would not advise it for those at risk to complications: e.g calculus build, deep bites or poor gum health. The repair rate at this clinic is 2% over a two year period on one tooth. Considering we fit them on 16 teeth this is low and manageable.

How long are fixed retainers required?

Teeth are part of the overall growth of the body and they can change as a part of natural development. Once fixed retainers are fitted,  clients rarely request for their removal. This is because they are used to it and do not impinge on their day to day life. The key aspect is the need for good gum health and little to no calculus development. If there are no retainers the teeth will change in time except in the very few.

Which teeth are most prone to relapse?

Relapse is most likely to occur when the original teeth were:

  1. Irregular front teeth.
  2. Teeth with gaps.
  3. Deep bites.
  4. Twisted/rotated teeth.
  5. Incisor teeth originally angulated.
  6. Impacted canines.
  7. Teeth originally at different heights.
  8. Tooth size variations when there is a mixture of teeth sizes.
  9. Crossbites.
  10. Arch shape changes.