If you offer clear aligners in your practice, you already know that they require strong retention in order to move the teeth as desired. But are you aware of the effects that trim lines have on retention?
A. scalloped margin
B. straight cut at the gingival zenith, twice as retentive as the scalloped cut, according to the study
C. straight cut at 2 mm above gingival zenith, 4 times as retentive as the scalloped cut
It was a significant finding that trimming the aligners differently has more of an impact than adding or removing engagers. “A relatively straight line trim is best, while a scalloped trim line (trimmed to follow the gumline peaks in between teeth) severely decreases fit and retention of the aligner,” Dr. Mah, one of the study’s authors, explains on his website. “Clinicians that do not understand these principles find themselves using many engagers/attachments on the teeth. Unfortunately, patients often complain about the number of ‘bumps on the teeth.’”
Dr. Mah notes 2 other misconceptions about clear aligner therapy related to trim lines and retention: 1.the manufacturer of the aligners provides the result of a good smile. 2. the dentist or orthodontist merely dispenses the aligners that are provided from the manufacturer. According to Dr. Mah, good results can only be achieved when the dentist or orthodontist takes a hands-on approach by working on the treatment through diagnosis, treatment staging, planning, clinical observation, and follow-up. Dr. Mah has found that proper selection of the trim line, use of thermoformed adjustment pliers, and planned overcorrection of tooth positions in the setup can drastically reduce the numbers of engagers/attachments used.
ClearCorrect understands that while their product may have to be adjusted based on the individual patient, application of the best trim line technique can lead to a better treatment experience. Based on the findings of the 2012 study, ClearCorrect started to trim its aligners with a smoother contour and a larger overlap with the margins. Because there is less risk of aligners impinging on the unattached marginal gingiva, the aligners are more comfortable with the technique, according to the company. Also, because the edge of the aligner is concealed further under the patients’ lip during everyday use, they’re also slightly more discreet. For this reason, ClearCorrect prefers 3 mm to 4 mm of gum to be included for an accurate impression.
As Dr. Mah notes, human biology is complex and treatments where all aligners are made in advance rarely work out as planned. That’s why ClearCorrect offers comprehensive support to dentists who are providing clear aligner treatment.
Learn more and explore some of these support topics on ClearCorrect’s website.