The treatment of pulpal diseases in primary teeth represents a significant challenge in public health, particularly in emergency dental care settings, where factors such as limited clinical time, low child cooperation, and structural constraints directly impact treatment effectiveness. In these contexts, conventional pulpectomy using zinc oxide-eugenol (ZOE), although effective, may present operational limitations that restrict its large-scale applicability in public health systems.

In this scenario, non-instrumental endodontic treatment (NIET), based on the concept of Lesion Sterilization and Tissue Repair (LSTR), has emerged as a simplified alternative. Among the available options, CTZ paste shows potential for single-visit application, reducing clinical time and technical complexity.

This study aims to evaluate the clinical and radiographic non-inferiority of CTZ paste compared to conventional pulpectomy with ZOE in primary molars with pulp necrosis, with or without abscess or fistula, treated in emergency dental care settings.

This is a randomized, pragmatic, controlled, non-inferiority clinical trial conducted at a single center, with clinical and radiographic follow-up at 3, 6, and 12 months. Participants will be allocated into two groups: (1) NIET with CTZ paste and (2) conventional pulpectomy with ZOE.

Primary outcomes include pain resolution and absence of clinical signs of infection. Secondary outcomes include radiographic success, clinical time, child behavior (Frankl Scale), need for retreatment, and oral health-related quality of life.

The findings are expected to provide robust evidence regarding the effectiveness of CTZ paste under real-world clinical conditions, contributing to the development of more accessible and effective protocols within public health systems, with the potential to expand access to conservative treatment and reduce early tooth extractions in pediatric dentistry.

Pulpal diseases in primary teeth remain a significant challenge in public health, particularly in emergency dental care settings. These environments are often characterized by limited clinical time, reduced child cooperation, and structural constraints, all of which may compromise the effectiveness and feasibility of conventional treatments. Pulpectomy using zinc oxide-eugenol (ZOE) is widely recognized as an effective treatment for necrotic primary teeth; however, its technical complexity and time requirements may limit its applicability in high-demand public healthcare systems.

In this context, non-instrumental endodontic treatment (NIET), based on the concept of Lesion Sterilization and Tissue Repair (LSTR), has been proposed as a simplified and less time-consuming alternative. This approach aims to disinfect the root canal system using antimicrobial pastes without mechanical instrumentation. Among these, CTZ paste has shown promising results due to its antimicrobial properties, ease of use, and potential for single-visit treatment, making it particularly suitable for emergency care scenarios.

The present study is designed to evaluate whether CTZ paste is non-inferior to conventional pulpectomy with ZOE in the treatment of primary molars diagnosed with pulp necrosis, with or without the presence of abscess or fistula, in emergency dental care settings.

This is a randomized, controlled, pragmatic, non-inferiority clinical trial conducted at a single center. Eligible participants will be children presenting with necrotic primary molars requiring urgent dental treatment. After enrollment, participants will be randomly allocated into two groups: (1) non-instrumental endodontic treatment using CTZ paste and (2) conventional pulpectomy using ZOE.

All procedures will be performed according to standardized clinical protocols. Clinical and radiographic evaluations will be conducted at baseline and at follow-up intervals of 3, 6, and 12 months. Blinded outcome assessment will be performed whenever feasible to minimize bias.

The primary outcomes of this study are pain resolution and the absence of clinical signs of infection, such as swelling, fistula, or pathological mobility. Secondary outcomes include radiographic success (e.g., absence or reduction of periapical/furcal radiolucency), total clinical time required for the procedure, child behavior during treatment assessed using the Frankl Behavior Rating Scale, need for retreatment, and oral health-related quality of life.

This trial adopts a pragmatic design to reflect real-world clinical conditions, thereby enhancing the external validity and applicability of the findings. The results are expected to provide high-quality evidence regarding the effectiveness and feasibility of CTZ paste in public health settings. If non-inferiority is demonstrated, this approach may support the implementation of simplified, cost-effective, and scalable treatment protocols, contributing to improved access to conservative dental care and reducing the need for early extractions in pediatric populations.

Inclusion Criteria:

• Pediatric patients presenting with:
• Irreversible pulpitis in primary molars;
• Pulp necrosis, with or without abscess, in primary molars.
• Primary molars with sufficient remaining tooth structure to allow endodontic treatment.
• Primary teeth in which the permanent successor tooth germ presents developmental stages compatible with Nolla stages 1 to 7, defined as:

Stage 1: Presence of bony crypt with no evidence of calcification; Stage 2: Initial calcification, with appearance of radiopaque points in the crown region; Stage 3: Approximately one-third of crown formation; Stage 4: Approximately two-thirds of crown formation; Stage 5: Crown almost complete, without full calcification; Stage 6: Crown completely formed, without initiation of root formation; Stage 7: Initial root formation.

• Clinical and radiographic conditions indicating feasibility of tooth maintenance through endodontic treatment, including:
• Permanent successor in developmental stages prior to Nolla Stage 8;
• Preservation of the bony crypt.

Exclusion Criteria:

• Pediatric patients presenting with:
• Reversible pulpitis;
• Indication for endodontic treatment in permanent teeth.
• History of allergy or hypersensitivity to any components of the obturation materials (e.g., CTZ paste or zinc oxide-eugenol).
• Clinical conditions that prevent adequate management in an outpatient setting.
• Primary teeth in which the permanent successor:
• Is in advanced developmental stages (Nolla Stage 8 or higher), and/or
• Presents disruption of the bony crypt, contraindicating endodontic treatment.
• Teeth presenting internal root resorption that compromises the feasibility of endodontic treatment.

Individual Participant Data (IPD) will not be shared. The decision not to share IPD is based on ethical and regulatory considerations, as the study involves pediatric participants and includes potentially sensitive clinical data. Data confidentiality and participant privacy will be strictly maintained in accordance with applicable data protection regulations and institutional ethics committee requirements.

Only aggregated data will be reported in scientific publications and presentations. No individual-level data will be made publicly available.