Analysis of failure factors in vital pulp therapy and construction of a “three-circle intersection” framework: a retrospective study of 103 cases

This retrospective study investigated the key clinical factors influencing the success of vital pulp therapy (VPT) by analyzing failed cases and evaluated the adjunctive role of a semiconductor laser in cases with different pulp exposure sizes. We included 103 VPT cases on mature permanent teeth with caries-induced pulp exposure, dividing them into four groups based on laser use and exposure size (< 0.5 mm or ≥ 0.5 mm). We graded factors including preoperative pulp vitality, intraoperative hemostasis time, and restoration quality. Treatment outcomes were assessed clinically and radiographically at 1, 3, 6, and 12 months postoperatively. The overall failure rate was 5.83% (6/103). Univariable analysis identified several factors significantly associated with failure (P < 0.05): hemostasis time ≥ 5 min (failure rate 41.67%), poor preoperative pulp vitality (failure rate 37.50%), and pulp exposure size ≥ 0.5 mm (failure rate 10.64%). Semiconductor laser use did not significantly affect the overall failure rate (P > 0.05). In the subgroup with pulp exposure ≥ 0.5 mm, however, the success rate was numerically higher in the laser group than in the control group (91.7% vs. 82.6%). The limited number of failure events in this subgroup (1 case in the laser group vs. 4 in the control group) resulted in insufficient statistical power for between-group comparison (post-hoc power ≈ 35%), so the difference was not statistically significant. This numerical trend suggests a potential advantage for laser in managing larger exposures, which requires validation in larger studies. In conclusion, our findings support a conceptualization of VPT success based on a 'three-circle intersection' model that integrates three established pillars: durable coronal sealing, accurate assessment of pulp status, and effective infection control during the procedure. Adjunctive technologies, such as lasers, may provide additional benefits but should not substitute for these fundamental principles. Clinicians should prioritize precise pulp diagnosis, high-quality coronal sealing, and strict asepsis over dependence on auxiliary tools.