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Installation of micro-screws

Micro-screws in orthodontics: At what age to place them.

Skeletal anchorage has been a revolution in modern orthodontics, allowing us to push the "limits" in extreme cases and avoiding surgical treatment in many of them. Despite all its benefits, the microscrews are not a perfect tool: they can cause discomfort or canker sores for the patient and can sometimes become mobile or even fall off. 

Crucial Factors for Stability:

Their stability will depend on different factors, one of them being the density and characteristics of the bone where they are inserted. It has been demonstrated that the stability of the microscrew is greatest when the thickness of the cortical bone is greater than 1 mm. High cancellous bone density will also be a favourable characteristic for placement. Unfortunately, depending on the location chosen for these devices, we will not always have optimal conditions to guarantee their stability. 

Primary Stability Considerations:

In order to be clear about all the factors that can influence the primary stability of the microscrewsWe will now proceed to list them:

  • Cortical and cancellous bone density. 
  • Place of insertion
  • Angle of insertion
  • Insertion depth
  • Diameter and length of the miniscrew 
  • Forces exerted during orthodontic treatment

Impact of Patient Age:

The type and density of bone varies according to the anatomical region of the mouth, but will also differ according to the age of the patient. The "immaturity" of the bone structures in growing patients, together with their faster metabolism, are two of the main reasons why the placement of microscrews is anecdotal compared to adult patients. In a child or adolescent, the response to the forces applied with our orthodontic or orthopaedic appliances will be much more favourable, which reduces the need to place microscrews. But in those cases where we do need to place them, this condition of skeletal immaturity can work against us, affecting their stability. 

Stages of middle phalanx maturation proposed by Perinetti et al.  

Skeletal Maturation and Bone Quality:

Reviewing the American Journal of Orthodontics and Dentofacial Orthopedics, one of the most renowned journals in orthodontics, we found studies that have evaluated the relationship between bone quality and skeletal maturation in the palatal area. The results suggest that the mass and thickness of palatal and nasal cortical bone increase with skeletal maturation, which may affect the stability and success rate of placement of the microscrews

Decisions Based on Careful Assessments:

Therefore, the decision to place a microscrew should be based on a careful assessment of the patient's individual characteristics, including skeletal maturity, oral hygiene and the anatomical characteristics of the insertion site. 

Interested in learning more about the placement of micro-screws in orthodontics? Join our classroom course! "SAS meeting in Madrid on the 18th and 19th of October and deepen your knowledge with experts in the field! Book your place now on our landing page and be part of this unique hands-on training opportunity - don't miss the chance to take your orthodontic practice to the next level!

Braga C. Bone quality in relation to skeletal maturation in palatal miniscrews insertion sites. Am J Orthod Dentofacial Orthop 2023. 

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