As general dentists and specialists working together to provide the best occlusion for each patient, we understand that comprehensive orthodontic treatment can provide significant benefits to improve function of the developing occlusion.
Many clinicians agree establishing canine guidance is a key functional goal. However, due to the late eruption, it may be one of the final items on our checklist in evaluating the developing dentition.
More troublesome than the delayed eruption is the occlusal dilemma they present as they emerge in a poor position. One of those challenges can be managing teeth that are late in development and ectopic in eruption. A single tooth in an otherwise ideal Class I occlusion can present as an occlusal dilemma when erupting in a poor position. From one six-month re-care visit to the next, there can be a dramatic change in the position of a late erupting tooth.
An example that is easy to miss is the second molar eruption. An upper second molar can take a buccal trajectory and erupt past the buccal cusp of the opposing lower molar. If it is up-righted from this position and moved into occlusion, there is a risk for opening the bite with the hyper-erupted molar. The mechanics needed for alignment must include control of both the vertical and the palatal movement. At the same time, the treatment goal must include preserving the detailed occlusion and alignment of all the other teeth.
In this situation, placing full fixed appliances is an option commonly recommended and has the benefit of controlling the entire dentition while correcting the single mal-posed molar. However, in a case with a well-established occlusion, it is a benefit to the patient and family to be able to offer a limited treatment plan when appropriate.
Unfortunately, using limited treatment with limited appliances can mean a loss of control and unexpected tooth movements. Achieving intrusion without adjacent tooth response is a mechanical challenge in any treatment plan and appliance configuration. To resolve this challenge we take advantage of a long understanding that anchorage is the key to limiting any unwanted movement. Anchorage can be found in many forms to date including implants, TADs, headgears and consolidation of a multiple tooth unit. Using a strong stabilizing wire joining two molars as anchorage can assist with management of a single tooth movement. The buccally tipped maxillary molar can be managed with a palatal wire to stabilize the upper first molars, while a light force is applied to the second molar that needs adjustment. The rest of the occlusion remains undisturbed. The palatal wire is well tolerated by the patient, oral hygiene is easily managed, and adjustment appointments are of short duration due to the simplicity of the mechanics.
This approach can tip the second molar palatally at the same time that the second molar, including the lingual cusp, is intruded. The intrusion is important to avoid opening the bite and minimizing the potential for lingual cusp interference. This is accomplished by positioning the anchorage wire apical to the second molar position. Once the second molar position is corrected it will be slightly out of occlusal contact. The palatal wire can be removed (and saved) to allow six to eight weeks for the second molar to erupt into occlusion before removing the bands on the first molars. If needed, a segment wire can be used to seat the second molar in occlusion. The patient benefits from a less complex orthodontic solution to the limited occlusal problem and the existing Class I ideal occlusion remains undisturbed.