Design of a Tooth Movement Functional Test Based on Periodontal Response to Applied Force

OBJECTIVES. Determining optimal magnitude as well as duration of force is important for clinicians because the magnitude of tooth root movement is positively correlated with the magnitude of applied orthodontic force. Biomarkers of orthodontic tooth movement in gingival crevicular fluid (GCF) could be utilized to determine how specific patient’s periodontal tissues react to the applied force. A quantitative relationship between the magnitude of force applied to a tooth and the amount of GCF biomarker should be determined. METHODS. Periodontal response to applied force was quantified by GCF flow measurements. In two participants, GCF was collected from ten maxillary teeth and ten mandibular teeth at baseline, initially and finally on each of six sequential aligners. Measured volumes were compared to sham aligners that applied no force. GCF was collected using Periostrips (Oraflow) and volume was measured by Periotron 8000 (Oraflow) (IRB#2021-61). Actual tooth movements were measured as crown movements on iTero digital models. RESULTS. We calculated the aligner ratio as sum of end GCF volume values on aligners divided by sum of initial GCF volume values on aligners applied to a tooth. Comparison of iTero-measured 3D distances with aligner ratios suggested a positive correlation relationship on maxillary teeth. Aligner ratio value less or equal 1 may indicate that a weekly period of aligner wear was sufficient. Aligner ratio value higher than one may indicate that a week period of aligner wear was too short, showed by increased GCF flow on the end of aligner wear. CONCLUSIONS. Simple measurements of GCF flow and iTero-measured distances may give us information about the relationship between patient’s capability to have teeth moved and frequency of Invisalign aligners