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Aligners vs. mini-plates - which one do we choose to treat open bites?

Open bites are traditionally one of the most feared malocclusions by orthodontists. The difficulty in controlling the vertical plane, coupled with the risk of relapse that these patients present, makes the treatment of this malocclusion a real challenge.

Many patients with OPEN BITE have a number of common features or characteristics in all of them:

  • Enlargement of the lower third of the face
  • Extrusion of posterior teeth
  • Inverted smile curve
  • Compression of arches

These features may lead us to consider a integral treatment with which to improve the patient's facial aesthetics. This, in turn, raises doubts as to whether or not the patient needs to undergo surgery in order to achieve the proposed objectives.

Treatment with mini-plates

This is where miniplates come into play. With these devices we can achieve results similar to surgery without the need to subject the patient to such an invasive procedure.

The mini-plates provide us with a greater anchorage and stability than individual micro-screws, which in turn allows us to apply more force to achieve intrusion of the posterior sectors. This posterior intrusion will cause an anterrotation of the mandible which will ultimately help us to close the bite.

In open bite treatment, it has been observed that mini-plates can achieve an average of 2.3 mm intrusion of the upper molars and 1.3 mm intrusion of the lower molars, which are sufficient to achieve notable changes in the patient profile.

Treatment with aligners

The posterior open bite that appears in some aligner treatments may lead us to think that achieving posterior intrusion with aligners is relatively simple, but the reality is quite different.

  • First, this open bite is not always caused by posterior intrusion. Anterior contacts, bowing or inadequate torque control of the posterior teeth can cause this phenomenon.
  • Second, posterior intrusion is achieved when we place something between the teeth that is thick enough to exceed the patient's resting vertical dimension. This
    will activate the levator muscles and assist posterior intrusion. The total thickness of the aligners (0.76 mm + 0.76 mm = 1.52 mm) is not sufficient to achieve this effect, especially in patients with vertical growth, who have an above average interocclusal clearance and weak muscle tone.

Like conclusionIf we want to solve the open bite by posterior intrusion, we will need skeletal anchorage (micro-screws or mini-plates) together with the treatment of aligners to achieve our objectives. Even if we plan for further intrusion into the virtual planning, that further intrusion, by the law of action-reaction, will be expressed as prior extrusion.

Steele BP, Pandis N, Darendeliler MA, Papadopoulou AK. A comparative assessment of the dentoskeletal effects of clear aligners vs miniplate-supported posterior intrusion with fixed appliances in adult patients with anterior open bite. A multicenter, retrospective cohort study. Am J Orthod Dentofacial Orthop. 2022;162(2):214-228.e4.

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