Azheen Ali, Darwn Abdulateef, lawand Barzanji
Objective: Posterior bite raisers (PBRs) induce temporary posterior disocclusion during fixed orthodontic treatment but may affect pulp vitality under prolonged occlusal load. Objective: To compare pulpal responses to injectable nanohybrid composite PBRs and resin-modified glass ionomer cement (RMGIC) PBRs at two heights (1–2 mm; >2–4 mm) in relation to gender and age. Methods: Eighty patients (16- 40 years old, with a mean age of 22.9 ± 5.7 years and an equal male-to-female ratio were assigned to four groups according to the material and height of PBRs, with twenty patients in each group. Cold testing and electric pulp testing (EPT) were documented at baseline, 1 week, 1 month, 2 months, and 3 months. The outcomes were divided into two groups: sensibility (positive or negative), and the differences among the four groups were compared in relation to gender and age. Results: At 3 months, negative pulpal responses were observed only in the composite groups: >2–4 mm (15%) and 1–2 mm (5%). Material choice was the strongest independent predictor of EPT threshold change (P=0.008), with the composite associated with significantly decreased responsiveness. The interaction between material and height was highly significant (p=0.012), indicating a fivefold higher risk of negative sensibility responses with high-volume composite than with RMGIC. Younger patients showed greater susceptibility to pulpal changes (p=0.03). Conclusions: Composite PBRs, particularly at heights exceeding 2 mm, are associated with increased pulpal stress, whereas RMGIC demonstrates superior pulpal stability and is recommended for initial orthodontic phases to minimize adverse biological effects.