A Qualitative Assessment of Invisalign® Techniques that Experienced Clinicians Employ to Manage Extraction, Vertical, and Transverse Plane Difficulties

Abstract

Objectives: Qualitative research is a standard research method in social sciences. It elicits the opinions of studied individuals to understand the issues to be solved. Findings commonly lead to hypotheses for subsequent studies. In medicine, it has been utilized only sporadically despite arguments to understand quality of life of patients. We applied the phenomenological qualitative research method to understand the thought process of distinguished Invisalign practitioners. In the absence of experimental evidence, clinicians typically rely on their past clinical experience, opinions of experts, and limited published case studies. In an effort to develop a more robust knowledge base to build clinician skills, this study was designed to assess how expert clinicians address the divergence between ClinCheck® simulation and actual tooth movements with Invisalign. Methods: Structured, open-ended interviews were conducted with five orthodontists who are known Invisalign experts of complex cases. Information were collected on: their approach to difficult transverse, vertical, and extraction treatment. Interviews utilized the conventional qualitative research protocol of recording, and then transcribing to analyze the data. Results: Some experts seek to push the limits of the aligner appliance whereas others still rely upon auxiliaries, such as fixed appliances, to achieve the treatment goals. In extraction treatment, the difficulty of tipping and root paralleling were counteracted by designing ClinCheck with virtual Tweed mechanics, where the plastic and attachments create “couple” type forces. Constricted arches receive expansion of ≤3mm, coupled with flattening of curve of Wilson by buccal root torque of approximately 5-10o. Open-bite treatment relies upon intrusion of molars and “relative” extrusion of incisors whereas, deep-bite receives overcorrection with premolar extrusion to level the curve of Spee. Conclusions: The expert orthodontist’s faith in Invisalign attachments, over-correction, and efficacy of virtual mechanics in ClinCheck are influenced by the malocclusion and their previous experience. Some experts seek to push the limits by re-configuring mechanics of the aligner appliance while others rely upon auxiliaries and braces to improve predictability. Hypothesis-driven experimental studies may now be designed.