Association Between Crowding Estimation and Extraction Recommendations in Orthodontics

Abstract

Little is known about how precisely orthodontists in the United States (U.S.) assess crowding in their own practices or at what range of crowding they decide to recommend extractions. The purpose of this study is to assess the relationship between estimated crowding in Class I cases and the recommendation for extraction treatment by orthodontists in the U.S. Secondary aims are to evaluate the accuracy and precision of clinicians’ estimations compared to objective manual measurements and determine if clinician sex, region, experience, method of crowding assessment, and extraction prevalence, play a role in extraction decision-making. An electronic survey was prepared using four Class I patients with anterior crowding selected from the University of Washington Orthodontics Clinic. The survey was sent to approximately 10,400 subjects through Facebook and the American Association of Orthodontists (AAO). In addition to the patient cases, questions about the clinicians were included. From the 297 responses received, it was observed that most clinicians recommended extraction once estimated crowding was classified as severe and reached 8-10mm in either the maxilla or the mandible. Clinicians’ estimations varied widely but on average, were precise within approximately 2mm of the objective measurements. There was a tendency to overestimate crowding, especially by clinicians practicing in the Northeast. Clinicians who reported that they routinely measured crowding or had recommended extractions to more than 10% of their patients were 1.2-2 and 1.4-1.6 times more likely, respectively, to recommend extraction in the cases.