Comparative Evaluation of Antimicrobial Efficacy of Different Root Canal Filling Materials Combined with Theobromine in Primary Teeth: A Research Protocol of an In-vitro Study

Introduction: Preserving the health and structure of primary teeth is crucial for a child’s growth and development. Premature extraction of primary teeth can lead to unfavourable changes in the eruption pattern and alignment of permanent teeth. To ensure the success of endodontic therapy in primary teeth, it is essential to use a biocompatible obturating material with effective antimicrobial properties. An ideal root canal filling material for primary teeth should not harm the periapical tissues, should promote the normal development of the permanent successor tooth and should undergo resorption simultaneously with root resorption. Additionally, it should be easy to place, adhere to the root canal walls, resorb if extruded beyond the apex, appear radiopaque on radiographs and not cause tooth discolouration. Zinc oxide Eugenol (ZnOE), iodoform-based pastes and calcium hydroxide are commonly used obturating materials for primary teeth. However, ZnOE has several disadvantages, including slow resorption, potential tissue irritation, bone and cementum necrosis and interference with the eruption of permanent teeth. Theobromine is a crystalline, water-insoluble alkaloid found in cacao plants. It has been shown to strengthen tooth enamel and exhibit antibacterial activity against microorganisms such as Lactobacillus acidophilus and Enterococcus faecalis. Need of the study: There is a need to identify root canal filling materials suitable for primary teeth that combine effective antimicrobial activity with biocompatibility and appropriate resorbability. Existing materials, such as zinc oxide eugenol, possess limitations that may compromise treatment outcomes. Therefore, investigating formulations enhanced with theobromine may represent a potential advancement in paediatric endodontics. Aim: To assess and compare the antimicrobial effectiveness of root canal filling materials, including zinc oxide eugenol and calcium hydroxide, combined with theobromine in primary teeth. Materials and Methods: An in-vitro study will be conducted at the Department of Paediatric and Preventive Dentistry at Sharad Pawar Dental College and Hospital, in collaboration with the Department of Microbiology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research (DMIHER), Sawangi, Wardha, Maharashtra, India, involving 25 patients aged 4-8 years. Microbial samples will be collected from infected primary molar teeth. The antimicrobial efficacy of four different root canal filling materials—zinc oxide mixed with theobromine, zinc oxide eugenol, calcium hydroxide mixed with theobromine and calcium hydroxide mixed with saline—will be evaluated. Vaseline will serve as the negative control. The mean zone of inhibition will be considered the primary outcome measure. Data will be tested for normality using the Shapiro– Wilk test. If the data are normally distributed, one-way Analysis of Variance (ANOVA) followed by Tukey’s post hoc test will be applied. If the data are not normally distributed, the Kruskal– Wallis test followed by the Mann-Whitney U test with Bonferroni correction will be used. A p-value of