Interproximal Reduction in the Refinement Phase of Invisalign Treatment

Interproximal enamel reduction (IPR) is a crucial and safe procedure that creates space between teeth to address orthodontic problems in the transverse and anteroposterior planes. This technique involves removing a clinically negligible amount of enamel from the mesial and distal proximal aspects of adjacent teeth. It aids in satisfactorily aligning the dentition and managing open gingival embrasures and Bolton discrepancies, making it an integral part of clear aligner therapy. The IPR technique predates the popularity of clear aligner treatment; however, as cited in this article, it is a commonly employed adjunctive approach with clear aligner therapy.

The current article is based on a comprehensive study that utilized the Australasian Aligner Research Database to identify the extent and impact of IPR on the refinement phase of clear aligner therapy. The research team meticulously examined the last 30 consecutive patients treated to completion by 11 orthodontists participating in the database, ensuring a robust and reliable dataset for their analysis.

According to their findings, approximately 40% of IPR-prescribed interdental contact points occurred in the refinement stage, which strongly indicates that IPR is a required procedure for ideal case finishing. In all phases of treatment, the anterior zone of the mandible was the most common site for IPR, demonstrating an IPR prescription rate of approximately 50% for the initial and refinement digital planning stages. Uprighting the post-treatment inclination of the mandibular incisors, refining the contact points for the better management of open gingival embrasures, establishing ideal overjet and overbite relationships, and achieving increased coupling and stability between the anterior teeth may be listed as the reasons for prescribing IPR in the refinement stage of aligner therapy. However, the findings of the study indicated that nearly half the patients examined received IPR multiple times at the same contact site during treatment, with some receiving it up to four times. One possible reason could be that the initial IPR treatment was ineffective in providing a complete resolution, leading to the need for subsequent prescriptions. Additionally, certain patients might have had specific conditions, such as increased sensitivity, that required ongoing intervention at the same sites. Lastly, it is also possible that orthodontists prescribed IPR repeatedly at the same sites when indicated as a precautionary measure to ensure excellent results and prevent unnecessary enamel removal.

Although the findings of this paper may reflect standard practices that some orthodontists follow, IPR — like many other treatment interventions — requires comprehensive and individual consideration. When determining the timing of IPR, our clinical experiences as clinicians underscore the importance of a patient-centric approach. Factors such as the initial discrepancy, orthodontic treatment stage, appliance activation, and patients' oral health must be carefully considered. Equally important is the patient's comfort and convenience and the potential impact of IPR on the overall treatment plan. This comprehensive approach ensures that the patient's needs and well-being are always at the forefront of the decision-making process.