Pulp blood flow changes in maxillary and mandibular anterior teeth after orthodontic retraction: a prospective study

Abstract

Background Previous studies of pulpal blood flow (PBF) changes in anterior teeth have been limited in the early phase of orthodontic treatment; less is known about the blood supply of anterior teeth in bimaxillary protrusion patients after orthodontic retraction. Methods Fifty bimaxillary protrusion patients (25 orthodontic patients ready for debonding and 25 non-orthodontic patients) were selected as study participants. The PBF of maxillary and mandibular anterior teeth were measured using laser Doppler flowmetry. For orthodontic patients, the PBF was measured at 1 day (T1), 1 month (T2), and 3 months (T3) after fixed appliance removal. Non-orthodontic patient PBF was measured as a control. Cone-beam computed tomography (CBCT) examinations before and after orthodontic treatment were performed for orthodontic patients to measure the root resorption. The anterior teeth in orthodontic group were further divided into subgroups according to root resorption and patient age. Results At T1 and T3, PBF changes did not differ significantly between the orthodontic and non-orthodontic groups. Maxillary lateral incisor, maxillary central incisor, and mandibular lateral incisor PBFs at T2 were significantly higher in the orthodontic group (P = 0.048, P = 0.04, and P = 0.021). No significant difference in PBF was found between the root resorption and non-resorption subgroups at any time point. Adolescent patients showed a higher PBF in the maxillary lateral incisor at T2 (12.23 ± 3.48) relative to that at T1 (9.10 ± 3.76) and T3 (9.81 ± 2.80) with statistically significant difference (P = 0.020). Conclusion For bimaxillary protrusion patients with four premolars extraction, PBF in the maxillary anterior teeth increased transiently after orthodontic appliance removal and then returned to non-orthodontic levels 3 months later. This effect was more pronounced in adolescents. The PBF of anterior teeth after orthodontic retraction may not be influenced by root resorption.

Macrophage M2 polarization promotes pulpal inflammation resolution during orthodontic tooth movement

“…Existing studies have found that mechanical force can exert pressure on the periapical blood vessels, reducing blood flow and oxygen supply to the pulp 8,9 . These impacts lead to pulpal hypoxia 10,11 . Our previous study also confirmed the expression of HIF‐1α and VEGF in dental pulp is enhanced by mechanical force 12 .…”

“…8,9 These impacts lead to pulpal hypoxia. 10,11 Our previous study also confirmed the expression of HIF-1α and VEGF in dental pulp is enhanced by mechanical force. 12 These highlighted the critical role of hypoxia signalling in the pulp inflammation during orthodontic tooth movement.…”

Endodontic–orthodontic interactions: a review and treatment recommendations

“…Courtesy Dr Teck Hong Oh. 4 fixed appliances, 17 orthodontic retraction, 18 and curve-of-Spee leveling 19 have confirmed that initial blood flow changes eventually return to normal values after OTM.…”

“…These findings differed from the earlier study by McDonald and Pitt Ford, 9 but the studies were not comparable due to methodological variations. However, recent studies on clear aligners and fixed appliances, 17 orthodontic retraction, 18 and curve‐of‐Spee leveling 19 have confirmed that initial blood flow changes eventually return to normal values after OTM.…”