Question:

Hi everyone,
I wanted to get some input on this case — a consult is planned this week. Patient is 23F ASA1. She is high caries risk, treatment plan was already made for caries management,endos, gingivitis etc. However one thing that was discussed was that given 46 and 36 have poor/hopeless prognoses, she was not thrilled with idea of implant placement - I wasn’t as well, given patient is young. One thought was potential for mesialization of the lower 7s and 8s to replace lower 6s. I understand that this is a HARD case and will likely put it through Clearly Reviews, but wanted to get some feedback - possible TAD use, where would I place them - never used TADs before but would love to incorporate them in my treatments.

Answer:

Mesialization of Second and Third Molars After First Molar Extractions Using TADs, Aligners, and Brackets

This article explores the clinical management of patients requiring first molar extractions, with an emphasis on orthodontic mesialization of the second and third molars using temporary anchorage devices (TADs), aligners, and brackets. The case includes strategic considerations, complications, and the decision-making process involved in achieving functional occlusion in a patient with prior decay and endodontic treatment.

Clinical Considerations for Molar Extraction and Mesialization

When first molars are deemed non-restorable (due to decay or failed endodontic treatment), the ideal goal is to close the resulting space by moving the second and third molars forward. This decision is especially critical in cases where the patient has not yet lost space due to molar drifting.

A fundamental biomechanical principle in orthodontics is the root count and distribution of forces. If the second and third molars on the lower arch each have two roots (totaling four roots distal to the extraction site) and the anterior segment—from second premolar through to the incisors—has five roots, then space closure will typically occur in a roughly 50/50 ratio, assuming no elastics or anchorage are used.

Occlusal Class Considerations

The patient's original occlusion must be assessed:

• Class III: Retracting teeth will work in the clinician’s favor.

• Class I or II: Retracting or mesializing molars without anchorage will worsen the Class II relationship.

• Asymmetry: Will result in a shift of the lower midline if anchorage isn't controlled.

In the presented case, the patient required extraction of lower first molars due to prior endodontic treatment and recurrent decay. The patient was 23 years old with a history of high caries risk. Treatment was only considered because the patient had been stable and cavity-free for several years. Still, the clinician emphasized that such cases should not be approached unless the patient has demonstrated excellent long-term oral hygiene and compliance, as incomplete or failed treatment could worsen the original condition.

Initial Treatment Strategy and Complications

The patient had a recurrent infection on a lower first molar and a Class II occlusion. Extracting the molar without anchorage would risk exacerbating the Class II relationship, so the plan involved using TADs to mesialize both the second and third molars with the aid of clear aligners.

A TAD was placed between the first and second premolars, and the initial attempt to mesialize the second molar involved using a NiTi spring and a power arm extending distal to the second premolar. However, the tooth rotated and tipped into the extraction space due to the lack of archwire control—a common issue when using aligners alone in such cases. The clinician concluded that this situation warranted the use of segmental brackets to prevent uncontrolled tipping.

Change of Strategy: Brackets and Direct Anchorage

After unsuccessful attempts with aligners and elastics, the decision was made to upright the tooth with aligners and then shift strategies. The patient, preferring not to pursue an implant, agreed to continue molar mesialization.

Brackets were bonded, and a new method was implemented:

• A C-chain was placed around the TAD and anchored to a cleat-style button.

• Composite was added to the teeth for patient comfort.

• The C-chain was used to pull both the second and erupted third molars forward into the first molar space.

• Later, a NiTi spring was used for additional mesialization.

Despite these efforts, some space opened distal to the lower canine, indicating minor unwanted distalization. However, overall, the Class II relationship improved, aided by Class II elastics used earlier in treatment.

Retrospective Insights and Posterior Open Bite

A regret noted by the clinician was an occlusal adjustment made during treatment. To manage posterior bite interference, some enamel had been removed from the distal occlusal surface. Later, once proper root angulation was achieved, this created an artificial posterior open bite that could have been avoided. Settling was expected over time, but the adjustment affected the final occlusal contact.

Final Outcomes and Recommendations

The case successfully achieved mesialization of the second and third molars into the first molar space using a combination of:

• TADs for anchorage

• Segmental brackets for controlled tooth movement

• Clear aligners for space closure and uprighting

An occlusal view revealed the limitations of aligners alone in root control. Even after uprighting, the root of the second molar remained in its original position. Only after applying a round archwire and re-engaging the bracket did proper control resume. The archwire had temporarily popped out, contributing to unwanted rotation, which was corrected using lingual C-chain mechanics.

At the end of treatment:

• The third molar required further derotation for improved contact with the second molar.

• A broader and more stable contact could have been achieved with continued lingual chain use.

Clinical Recommendations

1. Avoid complex cases in high-risk caries patients unless the patient demonstrates long-term stability.

2. Use segmental brackets when aligners alone fail to control rotation and tipping.

3. Utilize TADs effectively for anchorage, particularly in Class II or asymmetrical cases.

4. Avoid premature occlusal adjustments unless absolutely necessary, as these can create long-term bite issues.

5. Maintain flexibility in the treatment plan, as changes may be required based on clinical response.

Conclusion

This case illustrates the biomechanical complexity and strategic flexibility needed when managing first molar extractions in young adults. Success depends not only on technical skill and appropriate appliance use but also on careful case selection and patient compliance.