Leveling the curve of Spee using different sized archwires: a randomized clinical trial of blood flow changes

OBJECTIVES: To compare blood flow (BF) changes of teeth subjected to orthodontic forces during curve of Spee (COS) leveling using different archwires (AW). MATERIAL AND METHODS: Thirty subjects with COS > 5 mm were randomly assigned (1:1:1) into three groups based on the AW used: group 1: 0.017 × 0.025-inch stainless-steel (SS)AW, group 2: 0.019 × 0.025-inch SSAW, and group 3: 0.021 × 0.025-inch β-titanium (TMA)AW. In the 3 groups, a 5 mm-depth reverse COS was placed in the AWs. A laser Doppler flowmeter was used to measure BF at different time intervals (T0–T4). RESULTS: In the 3 AWs group, BF of all measured teeth was reduced 20 min after force application. Afterwards, the BF values started to increase until the baseline values were almost restored within 1 week. Differences in BF changes between the extrusion and intrusion subgroups were observed within groups 1 and 3 during the first 20 min of force application (P < 0.05). Similar BF changes were recorded using the 3 different AWs. BF changes were associated with tooth type and the amount of COS depth change. CONCLUSIONS: During CoS leveling, similar BF changes were recorded using the 3 different AWs. Tooth type and the amount of COS depth change were associated with BF changes within the first 20 min of force application. Greater BF reduction was found in premolars compared to incisors during the first 20 min of AW placement. CLINICAL RELEVANCE: It is important to select a type of applied forces that minimally affect the BF. Intrusive forces appeared to have lower negative effects on the BF of teeth during COS leveling. TRIAL REGISTRATION: ClinicalTrial.gov (# NCT04549948).