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orthodontic micro-screws

Microscrews in Orthodontics. Basics unvealed

Microscrews background in Orthodontics:

The introduction of microscrews in orthodontics is not as recent as we may think. Although it has become fashionable in recent years, microscrews were first used in 1985. However, the appearance of aligners together with the increasing number of adult patients in our practices has meant that we have to deal with more and more extreme cases and with more limitations than growing patients.

For this reason, microscrews have become a perfect ally in our day-to-day work to overcome some limits that we considered impossible with traditional orthodontics.

micro screw aligners

Microscrews are becoming more popular in orthodontics thanks to the use of clear aligners:

Although we like to treat any type of malocclusion with aligners, we always stress that we are aware of their limitations. And, in this aspect, aligners are not as effective as brackets in resolving certain malocclusions (the same is true for fixed orthodontics).

These mechanical limitations are what cause cases to get "stuck", seeing how some movements are not achieved no matter how many refinements we make. Often, the solution to our problems lies in the microscrews.

micro-screw in invisible orthodontics

The contribution of microscrews to orthodontics.

We keep talking about microscrews, but... have you ever stopped to think about what they bring to us? Because, in order to take the plunge into using them, they must outweigh the risks by far.

A microscrew gives us a bone anchorage point, theoretically 100% immobile (this is not always the case, on rare occasions microscrews move in the bone without increasing their mobility) on which we can rely to ensure that the movements we virtually plan are expressed in a more predictable way.

Orthodontic micro-screw

When are microscrews necessary in orthodontics:

Knowing their usefulness, the next question we can ask ourselves is: When do we have to place them? This question is more difficult to answer, so the answer will be depends. It depends on a number of factors, including:

- Amount of tooth movement.

The millimeters of movement we plan or, in other words, the complexity of the planned movement, will determine whether or not we need microscrews in orthodontics to achieve it.

The easiest way to assess your need is to know roughly what the predictable ranges of movement are with aligners.

For example, posterior intrusions of more than 2 mm or distalisations of more than 3 mm are considered "borderline" values. Any movement that equals or exceeds these ranges will alert us to the possibility of placing one or more micro-screws.

- Patient age:

As we mentioned, the numbers can be used as a guideline, but not as an exclusive guide for deciding to place microscrews.

Age is also a critical factor in knowing whether we need to place microscrews in orthodontics, since the movements in a growing patient will be achieved in a much more predictable way than in an adult patient. We will take this into account in our planning to know whether we will place microscrews or not.

- Number of teeth:

Although it may seem obvious, the fewer teeth we have in the mouth, the less anchorage is available to move the remaining teeth in it.

Therefore, in cases of periodontal patients, with multiple absences, microscrews will be a great support thanks to which we will be able to make certain movements that would be unthinkable to achieve only with aligners or even with brackets.

- Crown size:

Aligners rely on the retention of the plastic in the crowns to apply the planned forces.

The smaller the crowns, the more difficult it will be for the aligners to move those teeth. For example, let's compare a case where you want to do a PIR protocol, where your incisor crowns are over 10 mm length, to a case where your crowns, due to wear, are about 6 mm in length.

If you're wondering in which case the torque change is going to be better expressed, it's pretty obvious. In the second case, the aligners will perform much worse than in the first case due to the poor retention and, therefore, poor application of force.

microscrews microscrews to assist the change of torque together with the treatment of aligners, we will exponentially improve their predictability.

- Available anchorage:

In patients where we make sagittal corrections, we usually rely on intermaxillary elastics, either Class II or Class III.

These elastics, depending on patient conditions, may not always be viable or "safe". In those patients where we cannot afford to mesialize the upper or lower arch, depending on whether we are using Class III or Class II elastics respectively, we may need microscrews to use as an alternative anchorage point to distalize one of the arches and correct the sagittal discrepancy.

 Conclusions:

With these indications we end today's blog. We hope you have found it very useful and, if you have been bitten by the bug and want to learn how to place them, you cannot miss the course on microscrews in orthodontics that we will be holding in Madrid on October 18 and 19, 2024, where we will have a practical workshop to teach you how to place different types of microscrews and finally lose your fear of this very necessary technique. 

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