Also known as deviated midline or midline discrepancy, midline misalignment is a prevalent condition affecting many adults. A research review conducted in 2018 determined that the prevalence of midline deviation can be as high as 71%. The research review noted that some studies had found a majority of 39% for maxillary midline deviation from the facial midline and 46% non-coincidental dental midline.
Midline misalignment displays asymmetry in the center points of one or both patient’s dental arches. While the most common concerns around midline misalignment are cosmetic and often feature minimal side effects, most patients want to fix the problem.
In the past, midline correction has revolved around using dental braces, Invisalign, and, in some cases, veneers. However, what if there was a newer, more effective way of addressing this problem?
Well, you are in luck because there are multiple modern ways that you can use to help your patients align their midlines. This guide will take a detailed look at 3 of these ways.
3 Modern Ways of Correcting Midline Discrepancies
1. Mini-screws
If your digital X-ray machine identifies midline misalignment in your patient, you can leverage an orthodontic micro-implant mini-screw for treatment.
Miniscrews are orthodontic anchorage units fixed to the bone. These strengthen the orthodontic anchorage and help minimize the anchorage loss by supporting your patient's teeth in the anchorage unit. Working with NiTi archwires, mini-screws aid the occlusion treatment process, helping your patient achieve their desired results.
2017 Research Study
In a study to analyze mini-screw effects for treating midline deviation, researchers used a 15-year-old female complaining about crowding. After an examination, the researchers determined that the patient had facial asymmetry, which caused a mandibular deviation resulting from maxilla constriction.
After further intraoral inspection, the researchers detected a 4 mm lower midline shift to the right. The researchers initiated the treatment process with rapid maxillary skeletal expansion, where they inserted mini-screws into the canine-premolar areas and the buccal shelf.
Since the researchers needed to shift the patient's lower midline to the right-hand side, they inserted mini-screws into the left buccal shelf on the right canine-premolar region. The researchers concluded that acceptable correction of the lower midline deviation took four months to achieve.
2019 Research Study
In this study conducted in 2019, researchers used a 41-year-old woman with maxillary midline deviation toward the left caused by a previous orthodontic treatment involving the extraction of a left premolar on her maxilla. The patient's maxilla deviated 2.5 mm to the left.
The researchers used a mini-screw-anchored sliding jig to treat the midline misalignment. The total active treatment period was 32 months. Appropriately centered midlines and ideal occlusal were maintained after only 29 months of retention. The researchers noted that the procedure was successful.
2. Mini-plates
While mini-screws and mini-plates are temporary anchorage devices (TADs), the two are different.
A research article published in 2020 notes that while mini-plates are more challenging to install than mini-screws, they feature the benefit of staying away from the dental arch—this means avoiding root interference. Moreover, mini-plates are a perfect choice in cases where large movements are needed to treat midline misalignment.
Unlike mini-screws, which an orthodontist can install non-surgically, mini-plates require surgical installation. However, mini-plates boast a higher success rate.
How Effective Are Mini-plates?
A research study conducted in 2018 analyzed the effectiveness of mini-plates in treating open-bite and midline misalignment. The scientist used a 23-year-old female as their subject for the research study. The female patient had angle class II malocclusion, incompetent lips, bimaxillary dental protrusion, and an open bite.
The researchers initiated treatment by extracting the maxillary first bicuspids and her mandibular second bicuspids. Right after, the researchers fixed pre-adjusted bi-dimensional edge-wise appliances. After alignment, the researchers surgically installed titanium mini-plates into the patient's zygomatic buttresses bilaterally.
By the end of the treatment, the patient had achieved ideal mandibular autorotation and favorable maxillary molar intrusion. The patient also achieved perfect overjet with a significant improvement in their looks. The researchers concluded that the mini-plates were effective.
3. Hyrax Expander
The hyrax expander sits on the mouth roof and is fastened to the teeth. The maxillary skeletal expander holds its position and slowly pulls the patient's teeth into their new position in about 3 to 9 months.
What Does the Research Say About the Hyrax Expander?
A research study conducted in 2022 analyzed the effectiveness of the hyrax expander in aligning a left maxillary canine in the dental arch. The researchers used a 14-year-old boy as the subject in this study.
The boy was complaining of non-eruption of a left maxillary canine. While the patient's facial features appeared symmetrical from the frontal view, the mandibular midline deviated by 1.5 mm to the right when he was smiling.
The left maxillary canine was displaced to the labial side of the patient's left maxillary lateral incisor, with its apex ectopically and slightly erupting. The patient's mandibular anterior teeth were crowded, with a discrepancy of -3 mm in length. Their mandibular right lateral incisor and maxillary right lateral incisor were in a crossbite.
The researchers started the treatment process by extracting the maxillary left second molar. Then they installed a hyrax-type expander to the maxillary arch to aid in distal movement of the maxillary left first molar. The treatment process lasted for 37 months—by the end of this treatment period, the patient had achieved the desired results with the alignment of the teeth, suggesting that hyrax-type expanders are effective.
Overview
Midline misalignment is one of the most common conditions in the orthodontic space. Luckily, however, fixing this issue is straightforward. The patient enjoys improved symmetry and an attractive smile after the midline correction. This can be a confidence booster, especially for individuals with excessive misalignment.
This detailed guide looks deeper into the most recent methods you can use to fix midline misalignment effectively. These methods are backed by science—we have looked at research studies showing their effectiveness. After using these methods, you may need to recommend a retainer for your patient to maintain the new symmetry.
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