Severe Crowding with Lower Incisor Extraction

Main Topics Covered:

• IPR when gingival recession concerns

• Archform

• Pontic situation for lower incisor extraction

Transcript:

Okay, so we're going to be reviewing this extreme crowding case. We've talked previously about options, and it's been determined that the patient wants to extract one lower incisor to correct the crowding on the lower arch. For the upper arch, they are aware of the gingival issues that could result from the amount of expansion required, but the decision is to proceed without extracting any additional teeth beyond the lower incisor.

In every case, no matter how easy or complicated, I always start the same way—using a text expander template to go through the case line by line. In this case, I'll use the "review-cs-short" template, which provides a basic outline of what we want to review. There's also a "review-cs-long" template that goes into more detail about the rationale behind each line item, but for now, we'll stick with the short version.

First, I check the text comments to see if there are any relevant issues from the beginning. It looks like everything is fine here. The bite is properly set, and there are four passive aligners at the end, which is good.

Next, I look at the final canine and molar positions. We’re starting with a class one molar canine relationship on both sides, although there’s a crossbite. The goal is to maintain this class one relationship, and it looks like we’re finishing in the same class one molar canine position, which is great for this growing patient.

I also review the curve of Spee, which needs some correction. We’ll achieve some of this through relative intrusion as the teeth procline, which will help, but we might want to consider a bit more curve of Spee overcorrection. For the final arch form, there’s a lot of arch development occurring here. I don’t love that they’re waiting to move the second and first molars. Ideally, we’d keep the second molars in their position and avoid significant expansion, so I’ll make some changes to the final arch form and adjust the staging accordingly.

The upper sixes are nearly over-rotated, so we’ll undo some of that rotation. The premolars are properly rotated, and the arch form is ideal for the most part, with just a few minor tweaks needed.

Regarding the smile, it needs to shift to the left by a few millimeters, which is good to note. There isn’t much canting; the main issue is the midline that needs to be moved. In terms of Bolton discrepancy and IPR, this case is more about significant crowding rather than a Bolton discrepancy, so Bolton doesn’t play a major role here.

The gingival biotype looks good, with the tissue in the best condition we could hope for. However, we may want to consider more IPR on the upper arch to manage the overjet that will be created and to address any potential gingival tissue issues. Black triangles are not a concern at this point, so we’ll focus on IPR instead of restorative solutions.

For the worn and uneven gingival tissue, I would definitely recommend leveling the gingiva and doing buildups on the worn incisors. If this isn’t already in the treatment plan, it’s something to consider. I’ll leave a note for gingival leveling and adjust the plan accordingly.

When it comes to overjet, we might have a bit of excessive overjet, so I’ll consider doing IPR earlier in the treatment rather than waiting. Round tripping doesn’t seem to be an issue in this case, and while there may be slight extrusion of the central incisor at the end, it shouldn’t pose a significant problem.

I want to ensure there’s enough space for lateral incisor movement, avoiding any contact with the canine or central incisor. It appears the initial space provided isn’t sufficient, and then they overcompensate later, rapidly opening and closing space, which is not ideal. We’ll need to be mindful of this as we proceed.

We’re working with 90 trays here, which seems excessive. I may reduce the number slightly. Regarding pontics, I’m not a fan of using them in lower extraction cases, so I’ll recommend removing the pontic.

As for attachments and elastics, I’ll revisit those after making the necessary modifications. We’ll likely need to extrude the first premolar a bit more, assuming a crown will be placed on this lower premolar to improve proportionality. I’ll also adjust some rotation and add constriction to the lower molars to improve contact.

The contact between the lowers and uppers doesn’t look great, but that’s somewhat expected given the programmed buccal root torque, which may not fully materialize. We’ll need a bit more expansion there, which should be fine.

We’ve corrected the 6’s and reduced the movement of the sevens as much as possible. I’ll ensure that the expansion staging isn’t delayed and that we achieve the necessary superimposition for expansion. Since we’re extracting a tooth on the lower arch, we’ll need to match that on the upper with IPR in about 10 locations at 0.5mm each. However, I prefer starting with 0.4mm IPR, as it allows for more flexibility if further adjustments are needed.

In terms of crowding, we’ll perform IPR between the premolars to create sufficient space. I’ll outline specific areas for IPR in stage one, focusing on the 1.5-1.4, 1.3-1.4, and other critical areas, using a burr where necessary. We’ll avoid doing IPR on overly crowded areas like the 1.1-2.1 initially, focusing on distal contacts instead.

For extrusion, we’ll ensure there are appropriate attachments on the teeth, though we’re not doing significant extrusion in this case. The number of trays should be sufficient, though we may reduce it slightly. We’ll also address any issues with pontics, attachments, and elastics, ensuring proper placement and staging.

Next, I’ll review the gingival leveling, adjust attachments as needed, and confirm that we’re aligned with the overall treatment plan. There may be some risks of recession, but this plan offers the best approach given the lower incisor extraction.

We’ll continue by addressing the attachments and elastics. Given the crowding on the lateral incisor, I would recommend placing an attachment on the buccal surface of that tooth right from the start to ensure proper buccal root torque. I believe you could double stack the attachments on the second molars, especially since we’re dealing with significant crowding.

Moving on to attachments on crowns—there are none in this case, so that’s not a concern. For retention, we do need attachments for managing the deep bite, particularly on the lower premolars. We’ve already got attachments there, which is good.

When considering attachments for expansion, we have some in place, but it wouldn’t hurt to double stack them on the uppers, especially on the 7s, 6s, and 5s. This would provide additional control during expansion. Currently, we have attachments on the 1.6 and 1.5, but I’d recommend expanding this strategy.

For the upper lateral incisors, attachments are necessary. I’d suggest using non-beveled attachments to ensure a good grip for torque. Checking the attachment on the 4, we need to make sure there’s enough room to place it properly. If not, we’ll adjust its position slightly. Once that’s in place, everything else looks good in terms of challenging movements.

Later in the treatment, we might consider additional IPR for addressing black triangles, but right now, it’s not a pressing issue. We’ll continue to monitor that as the treatment progresses.

When it comes to elastics, you have some flexibility. You can choose to use them or not, depending on the situation. If we go with elastics, I’d lean towards a triangular configuration rather than a box elastic. Specifically, you could use a triangle elastic from the upper 5 and upper 6. Going to the upper 7 can be uncomfortable for patients, so I’d stick with the upper 5 and 6. On the lower, I’d likely use the lower 6 as the anchor point.

Now, looking at the crossbite correction, elastics may not be necessary for AP or vertical corrections. However, I’d move the elastics slightly more mesial to prevent them from slipping off the teeth.

Regarding the overall plan, I’d suggest using an Aevo in this case, with one-week aligner changes. Keep a close eye on recession. We’ll proceed with 60 active aligners, removing the pontic as discussed, and placing any additional attachments as needed.

The final aspect to consider is the gingival positioning of the 12. If there are concerns about where the gingiva will settle after the tooth moves buccally, we may need to adjust the plan. However, overall, this treatment plan represents the best approach given the decision to extract a lower incisor.

There are definite risks of gingival recession so monitor closely.