Magnitude of pulp space narrowing over time and contributing factors in teeth with vital pulp therapy: a retrospective cohort study.

Objectives: This study aimed to compare the magnitude of pulp space narrowing over time-measured as the change in pulp/tooth proportion from baseline-between mandibular molars treated with different types of vital pulp therapy (VPT) and their contralateral sound molars (controls). This study also investigated factors influencing the magnitude of pulp space narrowing in molars that have undergone VPT. Methods: This retrospective cohort study involved the assessment of bitewing radiographs of VPT-treated molars and controls at baseline and follow-up. Using reference points and lines on the radiograph, pulp/tooth proportions were measured by examiners. The intraclass correlation coefficient (ICC) was used to report examiner reliability. The changes in pulp/tooth proportions from baselines were compared between subgroups using multilevel mixed effect linear regression and the Wald test. Results: A total of 382 bitewing radiographs from 134 teeth were included. The follow-up period ranged from 6 to 84 months (mean, 27.12 ± 17.67 months). ICC values indicated good to excellent examiner reliability. Compared to the controls, changes in pulp/tooth proportion from baselines, indicating pulp space narrowing, were significantly greater in teeth with partial pulpotomy (at pulp chamber width) and coronal pulpotomy (at pulp canal width). Factors affecting the magnitude of pulp space narrowing included the more invasive type of VPT and the more severe preoperative diagnosis. Conclusions: The magnitude of pulp space narrowing was greater in VPT-treated molars than in controls. The more invasive type of VPT and severe preoperative diagnosis were factors contributing to the magnitude of pulp space narrowing.