# Injection Molding of Biodegradable Deciduous Teeth Dental Post
## 4 Conclusions  
This study successfully developed and evaluated biodegradable dental posts using PLA/PCL/ACP composites customized for deciduous teeth. Through innovative design and injection molding parameter optimization, the following results were achieved:  
Material properties: The PLA/PCL/ACP composite exhibits good flexural strength (21.936 MPa) and modulus (2.083 GPa) values, making it suitable for dental post applications. The material also exhibits hydrophilic properties with a contact angle of 73.73\({}^{\circ}\), enhancing compatibility with dental fillings.  
Biocompatibility: MTT experiments have confirmed that this composite material is non-toxic, has a cell survival rate of more than 70%, and has high biocompatibility for medical applications.  
Injection molding: Using [PERSON]'s experimental method, the optimal injection molding parameters were determined, and the minimum shrinkage rate obtained was 2.575%. Melt temperature has the most significant impact on shrinkage, followed by holding speed and injection speed.  
Overall, this study highlights the potential of PLA/PCL/ACP composites for the production of biodegradable posts for deciduous teeth based on comprehensive in vitro evaluations, including mechanical, thermal, rheological, and biological assessments. In contrast to conventional metal posts, quartz fiber-reinforced systems (e.g., D.T. Light-Post), and other PLA-based designs reported in previous studies, our approach features a distinct material formulation and injection molding process specifically tailored for pediatric applications. While the results are promising, this study is limited to in vitro analysis. Therefore, further preclinical and in vivo investigations are necessary to validate the clinical applicability of the developed PLA/PCL/ACP composite. In particular, future studies should incorporate functional simulations, such as cyclic loading, bonding performance with dental cements, and evaluations on extracted teeth to better reflect clinical conditions.  
Methodology, M.-W.W.; Software, M.-K.X.; Validation, M.-W.W. and M.-K.X.; Formal analysis, M.-K.X.; Investigation, M.-W.W. and M.-K.X.; Resources, M.-W.W.; Data curation, M.-W.W. and M.-K.X.; Writing--original draft, M.-W.W., M.-K.X., and S.E.H.; Writing--review and editing, M.-W.W.; Supervision, M.-W.W.; Project administration, M.-W.W.; Funding acquisition, M.-W.W. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Science and Technology Council, Taiwan, under grant number NSC 111-2221-E992-065.  
This study involved only commercially available cell lines and reagents. The cell line used was NIH/3T3 (BCRC 60091, Food Industry Research and Development Institute, Hsinchu, Taiwan). Culture media and supplements, including DMEM (Sigma, St. Louis, MO, USA) and fetal bovine serum (Gibco, Thermo Fisher Scientific, USA), were all commercially obtained. No primary cells or animal/human-derived tissues were used. Therefore, ethical approval was not required in accordance with institutional and journal guidelines.  
Not applicable.  
Data Availability Statement: The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors acknowledge the use of AI tools, specifically Microsoft Copilot, during the preparation of the initial manuscript draft and the revision process. Copilot was employed to refine the language, enhance textual clarity, and ensure technical accuracy in descriptions. All experimental designs, data collection, analysis, and interpretations were performed solely by the authors without AI involvement.  
The authors declare that they have no conflicts of interest.