Title of Study: Effect of External Cooling and Vibration, Counterstimulation, and Needle Type on Pain, Physiological, and Behavioral Outcomes During Inferior Alveolar Nerve Block in Pediatric Patients

Why was this study done? The inferior alveolar nerve block (IANB) is a dental injection used to numb the lower jaw and teeth in children. Many children find this injection very painful and scary. Bad experiences can make them afraid of the dentist for years. This study was designed to test different ways to make the injection less painful and stressful for children.

What did the researchers want to find out?

They planned to compare three different methods to see which one works best to reduce pain, distress, and physical signs of fear (like a fast heartbeat) during the injection:

External cooling + vibration (using a special device that cools and vibrates on the skin near the injection site)

Counterstimulation (gentle tapping or pressing with a cotton roll near the injection site)

A thinner needle (30-gauge instead of the standard 27-gauge)

Standard method (27-gauge needle with no extra distraction) - this is the control group

Who took part? The study enrolled 166 healthy children between the ages of 5 and 9 years who needed a lower jaw dental injection at Al-Mustansiriyah University Dental College.

What happened during the study?

Children were randomly placed into one of the four groups. All children received the same numbing medicine (2% lidocaine with epinephrine). Dentists gave the injection at the same speed for everyone. Researchers planned to measure:

How much pain the child felt (using the Wong-Baker Faces scale, where children point to a face showing their pain level)

How much pain the child showed (using the FLACC scale, which looks at face, legs, activity, crying, and comfort)

Heart rate and oxygen level (using a finger clip device)

How well the child cooperated (using the Frankl Behavior Rating Scale)

What outcomes are being measured? The primary outcomes are children's self-reported pain and observer-rated pain behavior. Secondary outcomes include physiological responses (heart rate and oxygen saturation) and behavioral cooperation scores. The study will compare changes in these measures across the four intervention groups.

What is the purpose of this research? The findings from this trial are expected to provide evidence to help dentists choose the most effective comfort measures to keep children calm and pain-free during lower jaw injections. The study aims to clarify whether distraction-based methods (cooling+vibration or counterstimulation) offer advantages over simply changing the needle gauge.

Were there any side effects or risks? Safety is being monitored continuously throughout the procedure via pulse oximetry (oxygen saturation) and heart rate tracking. The interventions are considered low-risk, and children who show excessive distress are withdrawn and managed according to standard care.

Who paid for this study? The study received no outside funding. The authors declared no conflicts of interest.

Where was the study done? Department of Pediatric Dentistry, Al-Mustansiriyah University, Baghdad, Iraq.

Study Design This is a prospective, parallel-group, randomized controlled clinical trial (RCT) conducted at the Department of Pediatric Dentistry, Al-Mustansiriyah University College of Dentistry, Baghdad, Iraq. The trial is designed to compare the effectiveness of three interventions versus a standard control in reducing pain, physiological stress, and behavioral distress during inferior alveolar nerve block (IANB) in pediatric dental patients.

Participants A total of 166 medically healthy children (ASA I or II) aged 5 to 9 years, who required dental treatment under IANB, were enrolled. Inclusion criteria included a baseline Frankl Behavior Rating of 2 or 3 (cooperative or potentially cooperative). Exclusion criteria were systemic illness, neurological or developmental conditions affecting pain perception, previous traumatic dental injection experience, allergy to lidocaine or epinephrine, and significant respiratory or cardiovascular conditions.

Randomization and Allocation Children were randomly assigned to one of four groups using a sealed-envelope method to ensure allocation concealment. Group sizes: Cooling + Vibration (n=40), Counterstimulation (n=41), 30-gauge needle (n=43), and standard 27-gauge needle control (n=42).

Interventions All injections use 2% lidocaine with 1:100,000 epinephrine, administered at a controlled rate of 1 mL/min by calibrated pediatric dentists.

Cooling + Vibration group: A thermomechanical device (Buzzy®, MMJ Labs, USA) is applied externally to the injection site for 30-60 seconds before needle insertion and remains in place during anesthetic deposition. The device provides simultaneous cooling and vibration.

Counterstimulation group: Gentle manual tapping or pressure with a cotton roll is applied adjacent to the injection site throughout the procedure.

30-gauge needle group: IANB is performed using a long 30-gauge needle without any distraction technique.

Standard control group (27-gauge needle): Routine IANB using a long 27-gauge needle, representing standard clinical practice.

Outcome Measures

Primary outcomes:

Child self-reported pain using the Wong-Baker FACES Pain Rating Scale (0-10) immediately post-injection.

Observer-rated pain behavior using the FLACC scale (Face, Legs, Activity, Cry, Consolability; 0-10) during the injection.

Secondary outcomes:

Heart rate (beats per minute) and oxygen saturation (%) continuously recorded via pediatric pulse oximetry.

Behavioral cooperation assessed with the Frankl Behavior Rating Scale (1-4).

All outcome assessments are performed by a blinded, calibrated observer. Children provide self-reported pain scores immediately after the injection using age-appropriate instructions.

Statistical Analysis Descriptive statistics will summarize baseline characteristics. Paired t-tests will compare within-group changes from baseline to follow-up. One-way analysis of variance (ANOVA) with Bonferroni post-hoc corrections will be used for between-group comparisons. The level of statistical significance is set at p < 0.05. Analyses will be performed using IBM SPSS version 28.

Ethical Approval The study protocol was approved by the Institutional Review Board of Al-Mustansiriyah University College of Dentistry (clinical trial number: MUPEDO4, REC199). Written informed consent was obtained from parents or legal guardians, and assent was obtained from children. The study complies with the Declaration of Helsinki (2013). Children who become excessively distressed are withdrawn and managed according to standard care.

Trial Registration (If applicable, the registry number and date would be entered here; the document lists an internal number MUPEDO4, REC199.

Inclusion Criteria:

Children aged 5 to 9 years. Requiring dental procedures under inferior alveolar nerve block (IANB) anesthesia.

Medically healthy children classified as American Society of Anesthesiologists (ASA) Class I or II.

Baseline Frankl Behavior Rating of 2 or 3 (indicating cooperative or potentially cooperative behavior).

Written informed consent obtained from parents or legal guardians. Age-appropriate assent obtained from the child. -

Exclusion Criteria:

Presence of systemic illness.

Neurological disorders.

Developmental conditions affecting pain perception.

Previous traumatic dental injection experiences.

Allergy or hypersensitivity to lidocaine with epinephrine.

Significant respiratory or cardiovascular conditions (to avoid confounding physiological monitoring).

Children who exhibit excessive distress during the procedure will be withdrawn and treated per standard care (this can be added as a withdrawal criterion if needed).

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Individual participant data (IPD) will not be shared because this study involves a vulnerable pediatric population (children aged 5-9 years). Informed consent obtained from parents/guardians did not include provisions for sharing de-identified data with external researchers. Additionally, institutional policies at Al-Mustansiriyah University restrict the sharing of pediatric health data to protect patient privacy and confidentiality. No data-sharing agreement or repository has been established for this single-center trial.

The outcomes assessor was blinded to group assignment. Participants, care providers (dentists administering the injection), and the investigator were not masked due to the nature of the interventions (visible device, manual tapping, or needle type).