Introduction

luxation injuries, incisors, caries, restorations, periodontium, TMA, tooth, orthodontic, trauma
PULP NECROSIS
The curve of Spee (COS) refers to the upward progression of the teeth curvature from the incisors through the premolars and molars. A deep COS is usually associated with an increased anterior overbite. During orthodontic treatment, COS is leveled by bringing the incisal edges of the anterior teeth and the buccal cusps of the posterior teeth into a horizontal plane level [The COS correction is usually achieved by posterior teeth extrusion and lower incisor intrusion [The application of orthodontic forces to teeth has been reported to induce molecular changes in the cells of the periodontal ligament, alveolar bone, and the pulp–dentine complex [The application of a contentious force to the teeth not only results in an inflammatory reaction within the periodontium but also has a significant effect on pulpal neural responsiveness, possibly for the entire duration of the orthodontic treatment [Most alterations in the BF that result from orthodontic treatment are reversible unless the pulp has been previously irritated by caries, restorations, or trauma [Intrusion applied to the teeth during orthodontic treatment is thought to have the greatest impact on the apical region. Therefore, a significant reduction in the BF during the application of a continuous intrusive force is expected. This is substantiated by results from trauma studies where intrusion injuries cause the highest percentage of pulp necrosis particularly in teeth with closed apices, compared to other luxation injuries [On the other hand, Sabuncuoglu and Ersahan [In the current orthodontic practice, 0.17 × 0.025-inch stainless steel (SS), 0.019 × 0.025-inch (SS), and 0.021 × 0.025-inch β-titanium (TMA) AWs are used for COS leveling during orthodontic treatment [To investigate BF changes of incisors subjected to orthodontic intrusive force during COS leveling using 0.017 × 0.025-inch stainless steel (SS) AW, 0.019 × 0.025-inch SS AW, and 0.021 × 0.025-inch β-titanium Titanium (TMA) AW at different time points (20 min, 48 h, 1 week, 1 month)To investigate BF changes of molars and premolars subjected to orthodontic extrusive force during COS leveling using 0.017 × 0.025-inch SS AW, 0.019 × 0.025-inch SS AW, and 0.021 × 0.025-inch TMA AW at the above 4 time pointsTo compare BF changes based on tooth type and type of force (intrusive and extrusive forces) within the same AW size groupTo compare BF changes between teeth in the three different AW size groups as per tooth type and type of forceTo investigate the association between BF changes, type of force, AW type, tooth type, and the amount of change in COS