## 1 Introduction  
Ossoeintegrated implants are vital for rehabilitating lost teeth in dertulous patients [1]. The alveolar process is influenced by factors that lead to bone loss from congenital absence, infections, trauma, or periodontitis. Tooth extraction is a major cause of this [2].  
Critical-size bone defects, which do not heal without intervention, cause structural damage and dysfunction, posing a challenge in maxillofacial surgery [3, 4]. Ensuring adequate bone volume at the recipient site is crucial for implant success. Guided bone -regeneration (GBR) is a widely used technique that excludes non-osteogenic tissues using barrier membranes, promoting osteogenic cell colonization [5; 6; 7].  
Various materials for resorbable and non-resorbable membranes have been developed for clinical use [8]. Collagen-based resorbable membranes are common in horizontal bone augmentation due to their biological properties [9]. Vertical augmentation benefits from titanium-reinforced polytetrafluoroethylene membranes, requiring soft tissue management and a second intervention for material removal [10; 11].  
A membrane combining the properties of both would expand the clinical applications, reducing discomfort and treatment time. Additive manufacturing plays a significant role in 3D printing polymers [12], using resins with photo-initiators [13]. However, most commercial resins lack biocompatibility and bioabsorbability [14]. Bioplastics from natural materials offer light-curable, biodegradable resins, allowing for the full elimination of material and byproducts, removing the need for second interventions in GBR [15].  
Vegetable oils are a promising source for bioplastic production, consisting of a mixture of unsaturated and saturated fatty acids and triglycerides, which contain reactive sites suitable for functionalization, enabling UV-induced polymerization and the processing of bioresins using 3D printing techniques [16; 17]. Among these oils, acetylated epoxidized soybean oil (AESO) has been highlighted as a photocurable liquid resin, utilizing its acrylate groups for easy polymerization via free radical reactions. However, due to its high viscosity, AESO cannot be printed alone using SLA-DLP printers [18]. Many studies report combining AESO with polyethylene glycol [19] or polyethylene glycol diacrylate [20], resulting in biocompatible structures with high cell adhesion and proliferation [21].  
The feasibility of this study is anchored in the use of animal models, specifically, rat calvaria, which are widely recognized as the gold standard for evaluating bone regeneration in induced critical-size defects [22]. These models allow for the creation of controlled and reproducible defects, facilitating the comparison of different biomaterials and bone regeneration techniques. Moreover, the bone physiology of rat calvaria shares similarities with that of humans, particularly in terms of bone healing behavior, making them ideal for the preclinical testing of novel materials [23].  
To the best of our knowledge, this study represents the first comprehensive exploration of a 3D printed customized membrane designed for controlled-resorption structural maintenance and bone formation in a rat calvaria defect model. Therefore, the aim of this study is to evaluate the osteogenic potential, structural integrity, and biodegradability of a novel soybean oil-based 3D printed resin membrane in guided bone regeneration. Specifically, the study seeks to analyze bone volume gain, membrane degradation potential, and histological response in a critical-size calvaria defect model in rats, testing the null hypothesis that the soybean oil-based 3D printed resin membrane does not promote significant differences in bone regeneration compared to the control conditions.