# Injection Molding of Biodegradable Deciduous Teeth Dental Post
## 1 Introduction  
Dental caries can affect deciduous teeth. According to the National Health and Nutrition Examination Survey (NHANES) from 2017 to 2018, 43.1% of U.S. children aged 2-5 years had experienced dental caries in their primary teeth, and 15.4% had untreated decay in their primary teeth [1]. Worldwide, dental caries mainly occurs in children around 2-5 years old. Extraction is the standard solution for treating children's teeth. However, it increases the chances of premature teeth loss and parafunctional habit development (e.g., speech problems, tongue thrusting), reduces masticatory efficiency, and results in a loss of vertical dimension. Additionally, it can be considered esthetically unpleasant, and psychological effects associated with early tooth loss are also an issue [2, 3]. Endodontic treatment using dental posts is an excellent option for treating caries in deciduous teeth. In clinical settings, making evidence-based decisions regarding intracranial post selection is essential. However, pediatric dentists often encounter significant challenges due to the variability and inconsistency in the existing research on intracanal posts. Dental posts protect the remaining tooth structure and come in various shapes; for example, their shape can be tapered, serrated, or threaded, with parallel structures also being used. Dental post materials must use biomedical materials, and the earliest known biomedical materials are precious metals [4]. Metal posts are known for their good retention and excellent fracture resistance [5]. Fiber posts, with modulus values close to dentin, can better distribute stress along the post [6,7]. Most studies on dental posts focus on dental caries in adults rather than deciduous teeth. Deciduous tooth posts are of critical interest because they must support the function of primary teeth while ensuring that they do not interfere with the eventual eruption and optimal positioning of permanent teeth. In deciduous teeth, root resorption is usually physiological and desirable, as it allows the underlying permanent successor to erupt [8]. This process absorbs the remaining hard tissue within the root canal and changes its shape. There is a risk of corrosion and enhanced inflammation for metallic dental posts if endodontic treatment leaks and bacteria enter the root canal. Another effect of using non-bioabsorbable materials in dental implants is metal hypersensitivity or metal allergy. The most common case of a patient with a metal allergy in dental implants is a lichenoid reaction characterized by oral lichenoid lesions [9]. Such cases occur in patients with metal dental implants exposed to metal allergens. Fiber posts are safer for dental post applications, but they experience problems related to debonding, which can cause fractures in the root structure and hinder the growth of new teeth. Therefore, choosing materials with low cytotoxicity that are safe for deciduous teeth is crucial for dental post applications. Recent clinical studies have begun to explore the use of resorbable PLA-based intracanal posts in pediatric patients. Recent studies have explored the development of PLA-based posts for dental applications. For instance, [PERSON] et al. [10] reported a PLA/PMMA blend with improved mechanical properties and biocompatibility, highlighting its potential as a sustainable alternative to conventional post materials. In contrast, conventional fiber posts such as the D.T. Light-Post(r) [11] and stainless-steel posts [12] have been widely used but present limitations in pediatric applications, including risk of debonding, corrosion, or interference with physiological root resorption. Despite these advances, comparative clinical studies remain limited, and the long-term in vivo resorption behavior of PLA-based posts in the pediatric population is not yet fully understood. These gaps underscore the need for further investigation into biodegradable post systems tailored for deciduous teeth. Among the available bioabsorbable materials, biodegradable plastics are a popular choice.