This study aims to compare two different methods of giving local anesthesia (numbing medicine) to children during dental treatment. The two methods are:

Dentapen® - a computer-controlled, pen-like device that delivers the numbing medicine slowly and steadily.

Traditional syringe - the standard metal syringe commonly used in dental clinics.

The main question is: Does using the Dentapen® device reduce child anxiety during the injection compared to the traditional syringe?

The study will include children aged 6-8 years who need to have an upper primary (baby) molar tooth extracted. The child's heart rate will be measured before and after the injection, and the child's anxiety level will be assessed immediately after treatment using the Wong-Baker Faces Scale (a picture scale showing different levels of worry or fear).

Participants will be randomly assigned (like flipping a coin) to receive the injection either with the Dentapen® or with the traditional syringe. Neither the child nor the person measuring the outcomes will know which device was used. The dentist giving the injection cannot be blinded because the devices look different.

This is a single-center, prospective, parallel-group, randomized clinical trial with a 1:1 allocation ratio, designed to compare child anxiety associated with local anesthetic administration using a computer-controlled local anesthetic delivery (CCLAD) system (Dentapen®) versus a traditional aspirating syringe. The study will be conducted at the Department of Pediatric Dentistry and Dental Public Health, Faculty of Dentistry, Cairo University, Egypt. The operator cannot be blinded due to the distinct appearance of the devices; however, participants (who will be supine with eyes closed during the procedure), the outcome assessor (who will evaluate recorded video footage cropped to obscure the injection site and the hand holding the device), and the statistician will be blinded.

Intervention Details:

Experimental (Dentapen®): The CCLAD device (Dentapen®, Septodont, Saint-Maur-des-Fossés, France) will be used in its ramp-up mode, which delivers a gradual, slow initial flow of anesthetic that increases to a constant flow over five seconds. This mode operates at the device's slowest speed (1 mL/90 s) at maximum force. Standard disposable 30-gauge, 20 mm needles and standard anesthetic cartridges (1.7 mL of 4% articaine with 1:100,000 epinephrine, Artpharmadent, Egypt) will be used. The technique will consist of a buccal infiltration followed by an intrapapillary infiltration.

Comparator (Traditional Syringe): A side-loading stainless steel aspirating syringe (Medesy® 4957/1, Italy) will be used with an identical anesthetic cartridge and needle (30-gauge, 20 mm). The same infiltration technique (buccal, then intrapapillary) will be performed, with manual control of injection speed and pressure.

Standardized Clinical Procedure: For all participants, the injection site will be dried and topical anesthetic (20% benzocaine gel, Iolite gel, Dharma Research Inc., USA) will be applied for one minute. Anesthetic will be deposited for the buccal infiltration at the depth of the buccal vestibule over the apices of the target upper primary first molar, with the needle bevel oriented toward the bone and aspiration performed prior to deposition. Intrapapillary infiltration will be performed one minute later, with the needle inserted 1-2 mm into the mesial and distal interdental papillae. The total volume of anesthetic and the rate of deposition will be recorded for each participant. Anesthetic efficacy will be confirmed using both subjective (patient report) and objective (dental probe) methods 3-5 minutes post-injection, prior to the dental extraction.

Outcome Assessment Methodology:

Primary Outcome (Child Anxiety): Measured immediately post-treatment using the Wong-Baker FACES® Pain Rating Scale (WBFS). The scale presents six faces ranging from 0 (no hurt/neutral expression) to 10 (hurts worst/extreme fear). The child will be shown the scale and asked to point to the face that best represents their feeling during the injection.

Secondary Outcome (Heart Rate): Measured in beats per minute (BPM) using a pulse oximeter (Fernández et al., 2021). Heart rate will be recorded twice: once immediately before the topical anesthetic application (baseline) and again immediately after the complete deposition of the local anesthetic.

Randomization and Allocation Concealment: A co-supervisor not involved in clinical procedures will generate a simple 1:1 random sequence using an online randomizer (random.org). Allocation concealment will be maintained using sequentially numbered, opaque, sealed envelopes prepared by the supervisors. The participant will draw an envelope immediately before the procedure.

Data Management and Statistical Analysis: All data will be recorded on paper case report forms, double-entered, and stored in a password-protected, encrypted online repository (Google Drive). Statistical analysis will be performed using SPSS (Version 24) and Minitab (Version 16). Normality of continuous data will be assessed using Kolmogorov-Smirnov and Shapiro-Wilk tests. Baseline characteristics and outcomes will be compared between groups using independent samples t-tests for normally distributed data or Mann-Whitney U tests for non-normal data. Categorical data will be analyzed using the chi-square or Fisher's exact test. The significance level will be set at α = 0.05.

Monitoring and Harm Management: The main supervisor will monitor the trial for protocol adherence, data integrity, and patient safety. Any adverse events, including but not limited to local complications (e.g., hematoma, paresthesia, needle fracture, dry socket, postoperative soft tissue injury) or systemic complications (e.g., allergic reaction, psychogenic reaction, local anesthetic toxicity), will be managed immediately according to the American Academy of Pediatric Dentistry (AAPD) guidelines. The trial will be paused for any serious adverse event and reported to the institutional ethics committee.

Ethics and Dissemination: Ethical approval will be obtained from the Research Ethics Committee, Faculty of Dentistry, Cairo University. The study will be conducted in accordance with the Declaration of Helsinki. Written informed consent will be obtained from each participant's parent or legal guardian, and verbal assent will be obtained from the child. Confidentiality will be maintained by assigning unique participant codes. The results of this trial will be submitted for publication in a peer-reviewed journal and presented as part of a Master's thesis in Pediatric Dentistry. No external funding has been received; the trial is self-funded by the principal investigator.

Inclusion Criteria:

• Children aged between 6 and 8 years.
• Cooperative children.
• Children having normal intellectual development.
• Children willing to provide assent and parent willing to provide informed consent.
• Healthy children with no systemic problems according to parental history.
• First dental visit.
• Children with bilaterally maxillary primary molars indicated for extraction.

Exclusion Criteria:

• Children with medical, physical, or mental conditions.
• Children requiring emergency dental treatment (cellulitis, abscess).
• Children whose parents refuse to sign the informed consent.

Participants were positioned supine with eyes closed during injection to prevent visualization of the device. Outcome assessors evaluated recorded videos where the injection site and the operator's hand holding the device were cropped. The statistician was also blinded to group allocation.