This randomized split-mouth clinical trial evaluated the efficacy of the Comfort-in needle-free injection system compared with conventional dental injection for local anesthesia during pulpotomy treatment in children.

Sixty children aged 5 to 8 years who required bilateral pulpotomy of primary first molars were included. Each participant received both anesthesia techniques in separate treatment sessions with an interval of at least one week. The order of anesthesia techniques was randomized: 30 children received conventional dental injection in the first session and Comfort-in needle-free injection in the second session, while the remaining 30 children received the interventions in the reverse order.

Pain perception during anesthesia administration and pulpotomy was assessed using the Face, Legs, Activity, Cry, Consolability scale and the Wong-Baker FACES Pain Rating Scale. Physiological parameters, including blood pressure, pulse, and oxygen saturation, were recorded before anesthesia, after anesthesia, and after pulpotomy. The amount of anesthetic solution used, duration of anesthetic effect, postoperative complications, and patient preference were also recorded.

The study was designed to determine whether the Comfort-in needle-free injection system could provide effective local anesthesia for pediatric pulpotomy while reducing injection-related pain, physiological stress responses, anesthetic volume, duration of postoperative numbness, and postoperative complications compared with conventional dental injection.

Local anesthesia administration is one of the major sources of pain, fear, and anxiety in pediatric dental patients. Conventional dental injections may cause discomfort due to needle penetration, tissue pressure, and deposition of anesthetic solution. These experiences may negatively affect child cooperation and future dental attendance. Needle-free injection systems have been developed as an alternative method to deliver local anesthetic solution without needle penetration.

This randomized split-mouth clinical trial compared the Comfort-in needle-free injection system with conventional dental injection in children requiring pulpotomy treatment of bilateral primary first molars. The split-mouth design was used to allow each child to serve as his or her own control, thereby reducing interindividual variability in pain perception and physiological responses.

A total of 60 children aged 5 to 8 years were included. All participants required pulpotomy treatment of bilateral primary first molars located in either the maxilla or mandible. Eligible children had no previous experience with local anesthesia or dental treatment, had no systemic disease or mental disability, had not used medications that could affect pain perception, and demonstrated positive or definitely positive behavior according to the Frankl Behavior Rating Scale during the initial examination.

Each child received both anesthesia techniques in two separate clinical sessions with a minimum interval of one week. In one session, conventional local anesthesia was administered using a dental injector after topical anesthetic application. In the other session, local anesthesia was administered using the Comfort-in needle-free injection system after topical anesthetic application. The sequence of interventions was randomized. Thirty children received conventional injection first and Comfort-in needle-free injection second; the remaining 30 children received Comfort-in needle-free injection first and conventional injection second.

In the conventional injection session, the injection site was dried and topical anesthetic spray was applied for 60 seconds. Local anesthetic solution containing articaine hydrochloride with epinephrine 1:100,000 was then administered using a 27-gauge dental injector. In the Comfort-in session, the injection site was similarly dried and topical anesthetic spray was applied for 60 seconds. Articaine hydrochloride with epinephrine 1:100,000 was administered using the Comfort-in needle-free injection system.

Pain during anesthesia administration and pulpotomy was assessed using two validated pediatric pain assessment tools: the Face, Legs, Activity, Cry, Consolability scale and the Wong-Baker FACES Pain Rating Scale. Physiological parameters, including systolic blood pressure, diastolic blood pressure, pulse, and oxygen saturation, were recorded before anesthesia, after anesthesia, and after pulpotomy. The total amount of anesthetic solution used, duration of anesthetic effect, postoperative complications, and the child's preference for anesthesia technique were also recorded.

The primary aim of the study was to compare pain perception during local anesthesia administration between the Comfort-in needle-free injection system and conventional dental injection. Secondary aims included comparing anesthetic efficacy during pulpotomy, physiological responses, amount of anesthetic solution required, duration of anesthetic effect, postoperative complications, and patient preference between the two anesthesia techniques.

Inclusion Criteria:

• Children aged 5 to 8 years.
• Children requiring pulpotomy treatment of bilateral primary first molars located in either the maxilla or mandible.
• Children with no previous experience of local anesthesia or dental treatment.
• Children who showed positive or definitely positive behavior according to the Frankl Behavior Rating Scale during the initial examination.
• Children with no systemic disease.
• Children with no mental or cognitive disability.
• Children who had not used medications that could affect pain perception, including antibiotics or analgesics.
• Written informed consent obtained from the parents or legal guardians.

Exclusion Criteria:

• Previous dental treatment experience.
• Previous local anesthesia experience.
• Uncooperative behavior during the initial examination.
• Presence of systemic disease.
• Presence of mental or cognitive disability.
• Antibiotic use within the last month.
• Analgesic use within the last 24 hours.
• Use of any medication that could influence pain perception.
• Refusal of parental or legal guardian consent.

Individual participant data will not be shared because the study included pediatric participants and specific consent for external sharing of individual participant-level data was not obtained. Aggregate study results will be reported in the manuscript.