Clinical Consideration Series. Dedicated to help you treat with confidence. Crowding.

Transcription

1 Clinical Consideration Series. Dedicated to help you treat with confidence. Crowding.

2 It s more predictable to treat crowding with Invisalign aligners if... anterior teeth are retroclined or upright. arches are narrow with posterior teeth tipped lingually, particularly cuspids and bicuspids. clinical crowns are not short. General treatment planning considerations. Options. The three basic options to address crowding are anterior proclination (buccal crown tipping), posterior dental expansion (buccal crown tipping) and interproximal reduction (IPR). With severe crowding, extractions may be needed. Please note that this may increase the complexity of the treatment and may require auxiliary techniques to be used in combination with the aligners. Check out the Extractions section in the Clinical Considerations Series to find out more about the Invisalign protocols for extractions. On adult patients where there is significantly more lower anterior crowding than upper crowding and the posterior occlusion very tightly interdigitated, the extraction of a single lower incisor instead of doing extensive lower anterior IPR should be evaluated. On treatments with posterior crowding, careful consideration to determine whether space may be created to bring into alignment the teeth positioned outside the arch will be required. If space is insufficient and cannot be created, extractions may be considered, as well as leaving the posterior crowding/crossbite untreated.

3 Crowding and teeth inclination. With crowding with lingually tipped anterior and/or posterior teeth, arch length will be increased by proclination of the anterior teeth and expansion of the posterior teeth (buccal crown tipping movements). Note that proclination of the anterior teeth will create relative intrusion, and reduce the overbite; if there is a deep bite present, additional absolute anterior intrusion will be required to create the necessary overjet space to further procline the lower anterior teeth to align them. With crowding with, IPR and the crowding; if this is not enough to prevent excessive proclination of the anterior teeth, distalisation or a more complex extraction treatment plan may be considered. Crowding and tooth size discrepancy. If there is tooth size discrepancy where the proportions of the upper and lower teeth don t match, either the wider teeth will need to be reduced with IPR (see example on the right), or the narrower teeth will need to be widened with restorations. If the tooth size discrepancy is too large, the extraction of a single lower incisor should also be considered. Assuming a Class I occlusion, a tooth size discrepancy may manifest itself either by presenting excess overjet when the teeth are completely aligned if the upper teeth are proportionally wider than the lower teeth, or by presenting upper spaces when the teeth are completely aligned since the lower teeth are wider than the upper; the alternative manifestation is for the lower teeth to be crowded if no spaces are present on the upper arch. When analysing the Bolton index, this patient showed a 0.6 mm anterior mandibular excess. 0.6 mm of IPR on the lower arch was planned on provider s request to achieve the goals.

4 IPR staging. o the interproximal contacts improves, which may lead to some round-tripping and once IPR starts, as the tooth width However, where possible the provider may request earlier IPR to reduce the amount of round-tripping. rowded teeth to facilitate their alignment and prevent them from binding may be requested; note that this will paces and will r bucco-lingual movements (round-tripping). Upper arch staging. On treatments with lower anterior crowding, the upper anterior teeth may be proclined and spaces may be created temporarily on the upper anterior teeth if in the process of aligning the lower anterior teeth, heavy inter-arch interferences are created and should be monitored.

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