The goal of this clinical trial is to learn whether a needle-free injection system can make tooth extraction less stressful for children than a conventional dental syringe. The study will include healthy children 6 to 12 years old who need a primary tooth extraction with buccal and lingual local anesthesia. The main questions are whether the needle-free method can lower anxiety, lower pain, and reduce changes in vital signs compared with the conventional syringe.

Researchers will randomly assign participants to 1 of 2 groups. One group will receive local anesthesia with a needle-free jet injection system. The other group will receive local anesthesia with a conventional syringe and a 27-gauge dental needle. In both groups, a topical lidocaine spray will be used before the injection, and the same anesthetic solution will be given. All tooth extractions will be performed by the same clinician using standard clinical procedures.

Participants' anxiety, pain, and vital signs will be checked before the procedure, after anesthesia, and after tooth extraction. Anxiety will be measured with the Face Image Scale (FIS). Pain will be measured with the Face, Legs, Activity, Cry, Consolability (FLACC) scale and the Wong-Baker Faces Pain Rating Scale (WBS). Vital signs will include systolic and diastolic blood pressure, heart rate, and oxygen saturation. No blood, saliva, or tissue samples will be collected, and no audio or video recording will be made.

Purpose: The aim of this study is to compare the clinical efficacy of the needle-free jet injection system and the conventional syringe used during tooth extractions in pediatric patients aged 6-12 years. In the study, it is aimed to make a scientific contribution to the development of more comfortable and acceptable anesthesia options in pediatric dentistry by evaluating the effects of both methods on children's pain perception, anxiety level, and physiological responses.

Scope: The study includes healthy pediatric patients aged 6-12 years who have an indication for extraction. Patients will be divided into two groups by randomization; in one group, a needle-free jet injection system will be used, and in the other group, buccal and lingual infiltrative anesthesia will be administered with a conventional syringe.

For the evaluation of pain and anxiety, the Face Image Scale (FIS), Wong-Baker Scale (WBS), and FLACC scale will be used, while systolic and diastolic blood pressure, pulse rate, and oxygen saturation will be used for monitoring physiological responses. Measurements will be performed at predetermined times before the intervention, after anesthesia, and after tooth extraction.

In light of the data to be obtained, the study aims to demonstrate the applicability, reliability, and contribution of the needle-free anesthesia method to patient compliance in children.

General Information Anxiety and pain experienced during dental treatment are among the most important factors that negatively affect compliance with treatment, especially in pediatric patients. Although local anesthesia is the most frequently used method for pain control in pediatric dentistry, needle application is one of the most important causes of anxiety and fear in children. In particular, injections administered to palatal and lingual regions with a dense nerve network are considered among the most painful procedures by children.

Needle phobia makes the treatment process more difficult in children, increases the perception of pain during the procedure, and may lead to the development of negative attitudes toward future dental appointments. In the systematic review study, it was reported that fear of needles can be seen in nearly 20% of the population and that this situation makes access to healthcare services more difficult.

In recent years, needle-free injection systems developed as an alternative to traditional needle-based methods in pediatric dentistry have emerged as an important option for increasing patient comfort. These systems administer the anesthetic solution by dispersing it into the tissue through a microscopic entry point approximately 0.15 mm in diameter under high pressure. Since this method provides an entry below the pain receptor threshold, pain during injection is minimal, and rapid and effective anesthesia can be achieved through the homogeneous spread of the solution over a wide area.

There are studies in the literature showing that needle-free injection reduces pain perception in children and provides a level of anesthesia similar to that of the conventional syringe. However, most of these studies have focused on maxillary palatal infiltration, and data regarding buccal and lingual infiltrative anesthesia applications in the mandible are quite limited. In addition, current studies have generally used Frankl or IDAF-4C scales in anxiety assessment, but the use of more visual and easy-to-apply scales in children (e.g., Face Image Scale) has remained limited.

Therefore, there is a need for randomized controlled studies investigating the effectiveness of needle-free injection systems in buccal and lingual infiltrative anesthesia applications in the mandible and their effects on pain, anxiety, and physiological responses in children.

Why Was This Research Needed? Local anesthesia administered with a conventional syringe during tooth extractions in children often leads to anxiety and compliance problems due to fear of needles and injection pain. This situation makes the treatment process more difficult and causes negative dental experiences in children.

Needle-free injection systems have the potential to reduce pain and anxiety by delivering the anesthetic solution into the tissue without using a needle. However, the effectiveness of this method and its effects on physiological responses in buccal and lingual infiltrative anesthesia applications in the mandible have not been sufficiently investigated.

For this reason, this study was planned to compare the clinical efficacy of the needle-free injection system, pain and anxiety levels, and also its effects on vital signs with the conventional syringe in children.

What Will Be Its Contribution to the Literature? This study will be one of the first studies to examine the effectiveness of needle-free injection systems in mandibular buccal and lingual infiltrative anesthesia applications in children. The combined use of visual and behavioral scales such as FIS, WBS, and FLACC to evaluate pain and anxiety levels in children will provide a new methodological perspective to the literature.

In addition, the simultaneous evaluation of vital signs (systolic/diastolic blood pressure, pulse, oxygen saturation) will reveal not only the subjective but also the objective physiological effects of needle-free injection systems.

The data to be obtained will strengthen the scientific evidence regarding the use of needle-free anesthesia methods in pediatric dentistry and contribute to the development of more comfortable, acceptable, and reliable alternatives in clinical practice.

Study Design This study is a prospective, randomized, and controlled clinical study to be conducted with the aim of comparing the effects of the needle-free injection system and the conventional syringe on pain, anxiety, and physiological responses during tooth extractions in children. The study will be conducted in accordance with the principles of the Declaration of Helsinki, and written informed consent will be obtained from all parents before participation. In addition, age-appropriate verbal explanations will be provided to the children.

Participant Selection

Inclusion Criteria:

Being between 6-12 years of age Having a primary tooth to be extracted with buccal and lingual anesthesia Being in category 2, 3, or 4 according to the Frankl Behavior Scale Being systemically healthy No known history of allergy to local anesthetics No antibiotic use in the last month and no analgesic use in the last 12 hours Not having acute dental pain Having sufficient cognitive ability to understand the anxiety assessment scales Voluntary participation with written parental consent

Exclusion Criteria:

Being under 6 years of age or over 12 years of age Displaying category 1 behavior according to the Frankl scale Presence of severe acute dental infection or a condition requiring emergency intervention Presence of a requirement for surgical extraction in the tooth indicated for extraction Incomplete root development of the underlying permanent tooth History of systemic disease (for example heart disease, uncontrolled asthma, epilepsy, diabetes) Inability to use pain/anxiety scales due to neurological or developmental disorder History of allergic reaction to local anesthetics or other drugs used Presence of hypersensitivity to odors or inhalation intolerance Refusal of participation by the child or parent

Randomization Participants will be divided into two groups by computer-assisted block randomization. In the experimental group, a needle-free jet injection system will be used, while in the control group, a conventional syringe will be used. Each child will be included in the study for only one tooth. The researcher performing the randomization will not participate in the clinical procedures.

Intervention Procedure Experimental Group In the experimental group, infiltrative anesthesia will be administered to the mandibular buccal and lingual regions using a needle-free jet injection system. Before the injection, topical lidocaine spray will be applied to the mucosa. The local anesthetic agent to be used will be the same in all participants: 4% articaine + 1/100,000 epinephrine.

Control Group In the control group, infiltrative anesthesia will be administered to the mandibular buccal and lingual regions using a conventional syringe with a 27-gauge dental needle. In this group as well, topical lidocaine spray will be used before the injection, and the same local anesthetic agent (4% articaine + 1/100,000 epinephrine) will be administered.

All tooth extractions will be performed by the same clinician in accordance with the standard clinical protocol.

Measurement Tools Behavior Scale

Children's behavior will be evaluated with the Frankl Behavior Rating Scale. This scale consists of 4 categories:

Category 1: Definitely negative (completely refuses treatment, distrustful, crying, excessively negative) Category 2: Negative (reluctantly accepts treatment, limited cooperation, but not withdrawn) Category 3: Positive (somewhat cautious but open to cooperation) Category 4: Definitely positive (satisfied with dental treatment, interested)

Anxiety Scale The FIS will be used to determine anxiety levels. This scale is a visual scale consisting of five different facial expressions, in which the most positive expression is scored as 1 and the most negative expression as 5. In the study, FIS will be used before the intervention, after anesthesia, and after tooth extraction.

Pain Scales The FLACC scale will be used for pain assessment. The scale consists of five categories: face, legs, activity, crying, and consolability. Each category is scored between 0-2, and the total score ranges from 0-10. FLACC will be applied based on observation after anesthesia and after tooth extraction.

The WBS will be used to measure the child's self-reported pain perception. This scale contains six different facial expressions and is rated from 0 (no pain) to 10 (the most severe pain). The child expresses the level of pain by selecting the face that best represents them. WBS will be applied after anesthesia and after tooth extraction.

Population/Sample of the Study:

The power analysis for the study was performed using G*Power 3.1 software. The test family was selected as F tests, and the statistical test was selected as ANOVA: Repeated measures, between-within interaction. As a result of the analysis conducted under the assumptions of a medium effect size of f = 0.25, significance level α = 0.05, statistical power (1-β) = 97.6%, correlation among repeated measures r = 0.50, and nonsphericity correction ε = 1.0 for a design including two groups (needle-free injection and conventional syringe) and three time points (before intervention, after anesthesia, after tooth extraction), it was planned to conduct the study with a total of N: 60 children, with n:30 children per group.

All data obtained in the study will be analyzed using IBM SPSS Statistics 25.0 (IBM Corp., Armonk, NY, USA) package software. The distribution characteristics of the data will be evaluated with the Shapiro-Wilk test. Descriptive statistics will be presented as mean ± standard deviation and median (minimum-maximum) for continuous variables, and as number and percentage (%) for categorical variables. In comparisons between groups, the independent samples t-test will be used for continuous variables with normal distribution, and the Mann-Whitney U test will be used for variables without normal distribution. For within-time comparisons, the paired t-test will be used for data conforming to normal distribution, and the Wilcoxon signed-rank test will be used for data not conforming to normal distribution. In the analysis of categorical data, the Chi-square test or, when necessary, Fisher's exact test will be used. For comparisons involving more than two categorical categories, the McNemar-Bowker test may be applied. To evaluate the group and time effects of the pain and anxiety scales (FIS, FLACC, WBS) and vital signs (systolic/diastolic blood pressure, heart rate, oxygen saturation), two-way ANOVA for repeated measures (or the Friedman test, which is its equivalent when parametric assumptions are not met) will be used. In all statistical tests, the level of significance will be accepted as p < 0.05.

Tests/Questionnaires-Data Collection Methods to Be Performed/Applied:

In this study, both psychological and physiological data will be collected. The data collection process will be carried out in 3 stages:

Before the procedure (baseline measurement), After local anesthesia, After tooth extraction.

1. Anxiety Measurement

   • FIS: It is a visual scale used to evaluate children's anxiety levels. It consists of five different facial expressions, and the child selects the face that best represents their current feeling. The scale is a frequently used instrument in the assessment of dental anxiety in children, with proven validity and reliability. In the study, FIS will be applied before the procedure, after anesthesia, and after extraction.

2. Pain Measurement

   • FLACC Scale: It is an observational pain assessment tool. It includes five categories: facial expression, leg movements, activity, crying, and consolability. Each category is scored between 0-2, and the total score is calculated between 0-10. In the study, it will be applied by observation after anesthesia and after extraction.
   • WBS: It is a visual scale that allows the child to express their own pain. It includes six different facial expressions and is scored from 0 (no pain) to 10 (the most severe pain). The child selects the face appropriate to the pain they feel. In the study, it will be applied after anesthesia and after extraction.

3. Physiological Measurements

   • Blood Pressure (systolic/diastolic), Heart Rate, and Oxygen Saturation: These will be measured to evaluate children's physiological responses. A digital pediatric blood pressure monitor and a pulse oximeter will be used. Measurements will be performed before the procedure, after anesthesia, and after extraction.

4. Behavioral Observation • Frankl Behavior Rating Scale: It is an observational scale that classifies the child's level of cooperation in the dental clinic into four categories (definitely negative, negative, positive, definitely positive). It will be recorded by the researcher during clinical procedures.

All data collection tools will be introduced to the research team before the start of the study, and a standard application protocol will be established. Data will be collected within the framework of ethical rules, with due consideration for children's safety and comfort.

In this study, the effects of the needle-free injection system and the conventional syringe on pain, anxiety, and physiological responses during tooth extractions in pediatric patients will be evaluated with a randomized controlled clinical study design.

Children participating in the study will be divided into two groups by randomization:

• Group 1 (Experimental Group): Local anesthesia will be administered with a needle-free jet injection system.
• Group 2 (Control Group): Local anesthesia will be administered with a conventional syringe (27 gauge dental needle).

In both groups, the same substance (4% articaine + 1/100,000 epinephrine) will be used as the anesthetic agent, and topical lidocaine spray will be applied to the mucosa before injection. Tooth extraction procedures will be performed by the same clinician in accordance with standard clinical protocols.

Measurements will be performed at three time points during the study: before the intervention (baseline measurement), after anesthesia, and after tooth extraction. During these time periods, children's anxiety (FIS), pain (FLACC and WBS), and physiological parameters (systolic/diastolic blood pressure, heart rate, oxygen saturation) will be recorded.

Medical histories of all children included in the study will be taken, and allergy risks will be questioned. Children with a known allergy to local anesthetics or a history of systemic disease will not be included in the study. In the event that any adverse condition is observed during the intervention, the procedure will be stopped immediately and the necessary medical support will be provided.

Applications have been planned with due consideration for children's safety and comfort. The methods used are procedures that have previously been applied safely in children and whose effectiveness has been demonstrated in the literature.

Hypothesis(es):

Main Hypothesis (H1): Local anesthesia administered with needle-free injection results in lower anxiety, lower pain level, and less physiological stress response during tooth extraction in children compared with the conventional syringe.

Null Hypothesis (H0): There is no significant difference between the needle-free injection and conventional syringe methods in terms of anxiety, pain, and physiological responses in children.

Limitations of the Study: This study included only children aged 6-12 years and teeth to be extracted with buccal-lingual infiltrative anesthesia. The findings obtained cannot be directly generalized to different age groups or other dental regions. The study will be conducted in a single center, and only 4% articaine + 1/100,000 epinephrine will be used as the anesthetic agent. Since anxiety and pain evaluations will be made with self-report (FIS, WBS) and observation-based (FLACC) scales, subjective factors may not be completely eliminated. In addition, since vital signs will be recorded with short-term measurements, long-term physiological effects cannot be evaluated.

Inclusion Criteria:

• Being between 6-12 years of age
• Having a primary tooth to be extracted with buccal and lingual anesthesia
• Being in category 2, 3, or 4 according to the Frankl Behavior Scale
• Being systemically healthy
• No known history of allergy to local anesthetics
• No antibiotic use in the last month and no analgesic use in the last 12 hours
• Not having acute dental pain
• Having sufficient cognitive ability to understand the anxiety assessment scales
• Voluntary participation with written parental consent

Exclusion Criteria:

• Being under 6 years of age or over 12 years of age
• Displaying category 1 behavior according to the Frankl scale
• Presence of severe acute dental infection or a condition requiring emergency intervention
• Presence of a requirement for surgical extraction in the tooth indicated for extraction
• Incomplete root development of the underlying permanent tooth
• History of systemic disease (for example heart disease, uncontrolled asthma, epilepsy, diabetes)
• Inability to use pain/anxiety scales due to neurological or developmental disorder
• History of allergic reaction to local anesthetics or other drugs used
• Presence of hypersensitivity to odors or inhalation intolerance
• Refusal of participation by the child or parent

No individual participant data will be shared. Personal information obtained during the study will be kept confidential, and any publication of the study results will not disclose participant identity.