Pain and anxiety management during injection of local anesthesia are major challenges in pediatric dentistry. The injection of local anesthesia is often perceived by children as the most painful step , The introduction of computerized control local anesthetic delivery systems (CCLADS), such as the Star Pen device, has provided a modern approach for reducing discomfort during anesthesia. Additionally, the integrated music distraction feature enhances relaxation and cooperation during treatment.

: the aim of this study is to evaluate star pen computerized Local Anaesthesia in reducing child pain during injection, and its impact on child behavior during extraction of primary molars.

Materials and Methods: The research will be conducted in the form of a double-blind randomized controlled clinical trial with a parallel design. A total of 40 healthy children aged 4-6 years will be selected from the Pediatric Dentistry Department, Faculty of Dentistry, Pharos University in Alexandria, Egypt. Cooperative Children with Frankl behavioral rating scale scores of 3 or 4 will be selected. Each child chosen will have at least one maxillary or mandibular primary molar that requires extraction. The guardian's written informed consent will be obtained. Participants will be assigned into two groups of 20 children each based on the dental arch where the extraction will be performed: Group I (mandibular group); and Group II (maxillary group). Each group will be further subdivided into two subgroups: test group using the star pen computerized local anesthesia, and control group using the conventional method; IANB in the mandible, and infiltration local anesthesia in the maxilla according to the method of delivery of local anaesthesia. In the present study, pain during injection will be assessed by three methods: physiologically using the heart rate, objectively using Sound, Eye, Motor (SEM) scale, and subjectively using a modified face scale from the Maunuksela scale. In each child extraction of one primary molar will be performed according to the AAPD and child behavior will be assessed using Frankl Rating Scale.

Results: To obtain the study's results and conclusions, data will be collected, tabulated, and statistically analysed using SPSS version 26.0, with a significance level set at p < 0.05.

Inclusion Criteria:

1. Completion of the written informed consent form by parents/guardian.
2. Children aged between 4 and 6 years.
3. Medically fit patients classified as (ASA I).
4. Cooperative children with a Frankl Behaviour Rating Scale of 3 or 4.
5. Patients whom their primary molars are indicated for extraction, according to criteria of extraction of (AAPD).

Exclusion Criteria:

1. Children with a history of allergy to local anaesthetic agents.
2. Children who receive any analgesic drugs at least 24 h before treatment.
3. Any inflammation or lesion in the injection site.
4. Patients who have previous bad experience of dentistry to eliminate the possible impact of the child's previous painful or stressful experiences.
5. Child coming for emergency treatment of pain.
6. Teeth with ankylosed roots.