## 1 Introduction  
Preventing disease or interrupting its progression at the earliest possible stage while preserving the maximum amount of healthy, viable tissue is a fundamental principle of minimally invasive dentistry [1]. In this context, vital pulp therapy (VPT) prioritizes the preservation of dental pulp and its physiological functions, including proprioception, innervation, and vascularization, which are lost following root canal therapy (RCT) [2, 3]. Choosing between VPT and RCT depends on the careful consideration of the predicted success rate in an individual case. Various factors might influence the choice of VPT modality and its overall outcome, such as adherence to aseptic protocols, the preoperative inflammatory state of the pulp, and selecting an appropriate pulp capping material [4]. However, statistically sound evidence of the effect of patient-related factors remains sparse, with a significant gap in our understanding of how they interact to influence treatment outcomes.  
VPT is a less technically demanding procedure, requiring less time and cost than RCT, making it a more accessible and efficient treatment alternative in appropriate cases [5, 6]. Furthermore, RCT-treated teeth exhibit a higher risk of long-term complications, such as increased susceptibility to fractures, which can compromise the longevity of the tooth [7; 8]. By preserving pulpal vitality, VPT enhances the tooth's natural defense mechanisms and supports continued dentinogenesis, contributing to better long-term prognoses [9]. A systematic review in 2024 [10] indicated that the success rate of VPT in decayed mature teeth was >90%.  
Despite the benefits of VPT, accurately diagnosing pulpal inflammation remains challenging. The traditional classification system of the American Association of Endodontists (AAE) relies on a binary distinction between reversible and irreversible pulpitis, often leading to misclassification and overtreatment [11; 12]. [PERSON] et al. (2017) proposed a diagnostic system based on symptoms, categorizing pulpitis into four stages: initial, mild, moderate, and severe, with pulpal exposure and pulotomy indicated only in select categories [13]. However, only a few studies currently examine its efficacy in predicting the outcomes of VPT procedures [14].  
Another critical factor influencing the success of VPT is the selection of pulp capping materials, which must provide biocompatibility, antimicrobial activity, and a stable seal against bacterial microleakage [4; 15]. Mineral trioxide aggregate (MTA) has long been considered the gold standard owing to its excellent sealing ability, high biocompatibility, and capacity for inducing hard tissue formation. However, MTA has notable drawbacks, including tooth discoloration (up to 33% of cases), long setting time (approximately 2-3 h), and difficult handling properties [16].  
In contrast, Biodentine (Septodont Ltd., Saint Maur des Fausses, France) offers improved handling and discoloration resistance, with a reported setting time of 10-12 min [17]. The success rate with Biodentine in VPT (83-96%) is comparable to MTA [15; 18; 19]. Additionally, it can be used as a temporary material to fill the cavity, easing its clinical applications. However, its actual setting time is often significantly longer than the manufacturer's claim, raising concerns about its sealing ability shortly after application [14].  
This pilot study aims to estimate the sample size required for a multivariate regression model assessing how capping material, patient age, sex, and pulp diagnosis influence the success rate of VPT. The findings will also guide the design of more extensive, statistically powered studies to definitively assess the impact of these variables on VPT success.