Primary outcome: blood flow (BF) (Fig. 
MP
BF measurement using LDF (courtesy of Alhaija et al. 2021) [Measurements of the BF were taken by the use of LDF (Moor lab, Moor instruments, UK) with a wavelength of 780 nm and a dental probe MP 13 (Moor instruments, UK; 2 fibers, 0.25 mm diameter, centers 0.5 mm spaced a part). The flowmeter was calibrated according to the manufacturer’s instructions. Room temperature was maintained from 20 to 25 °C. Volunteers were provided with 15 min’ rest before each session.Before starting the measurements, a silicone splint was fabricated to stabilize the dental probe during the measurements. The retentive areas of the brackets were covered with a layer of utility wax. Holes were made below the imprints of the brackets in the mold with a stainless-steel drill of 1.5 mm diameter to allow the probe to pass through the mold to touch the teeth to allow measurement of teeth on the same position at different times. The silicone splints were fabricated to extend over the attached gingiva. The retentive areas of the brackets and the labial gingiva were covered with utility wax. In addition, 4 cotton rolls were applied in the gingival sulcus to keep the lower lip and cheeks away. This helped in isolating the teeth during measurements to minimize contamination of the blood flow signals from adjacent tissues [BF was recorded at 5 points:Before placement of interventional AWs in both groups. These values were considered the basal blood flow (T0).Twenty minutes after placement of the interventional AW (T1).Forty-eight hours after placement of the interventional AW (T2).One week after placement of the interventional AW (T3).One month after placement of the interventional AW (T4).