Profiling Root Canal Treatment Fear in Adult Endodontic Patients: A Cross-Sectional Study of Fear Dimensions, Dental Avoidance, and Negative Experiences

1. Introduction

Dental anxiety and dental fear are clinically important psychological variables that affect the timing of dental treatment, tolerance of dental procedures, patient-clinician communication, and subsequent dental attendance [1,2]. In this article, dental anxiety refers to apprehension related to the dental setting or an anticipated dental procedure, whereas dental fear refers to a response to a more identifiable stimulus, such as injections, pain, instrument sounds, or a specific dental treatment [2,3]. The term dental phobia is reserved for a more severe diagnostic construct requiring formal clinical criteria, and no diagnosis of dental phobia was made in this study [3,4].

Dental fear and anxiety are common, but their severity and clinical consequences vary between individuals. A systematic review and meta-analysis estimated the global prevalence of dental fear in adults at 15.3%, high dental fear and anxiety at 12.4%, and severe dental fear and anxiety at 3.3% [5]. Dental fear has been associated with female sex, younger age, previous negative dental experiences, psychological distress, and poorer perceived oral health [2,6]. Dental fear should therefore be considered not merely a subjective discomfort but a clinical variable that may influence the use of dental services.

The clinical significance of dental anxiety extends beyond transient distress during treatment. High dental fear is often conceptualized within a fear-avoidance cycle, in which fear contributes to the postponement of dental visits, symptom-driven rather than preventive attendance, the accumulation of more complex treatment needs, and the reinforcement of negative dental experiences [7,8]. This cycle may affect oral-health-related quality of life and broader health behaviors [9,10]. From this perspective, the clinically relevant question is not only whether a patient is anxious, but also which cues and previous experiences maintain that fear.

Multiple pathways have been proposed for the acquisition and maintenance of dental fear. Direct painful or uncontrollable dental experiences, observation of others' negative experiences, verbal information from family or the social environment, negative information from media sources, and cognitive perceptions of threat or uncontrollability may contribute [8,11,12]. Psychological studies likewise indicate that fear may be acquired through direct conditioning, observational learning, and verbal information [13,14,15]. This framework is particularly relevant to RCT, which patients often perceive as painful, lengthy, invasive, and uncertain [16,17].

Although anticipated pain occupies a central place in patients' perceptions of RCT, expected and experienced pain do not always correspond [18,19]. Previous studies have shown that dental anxiety may be associated with preoperative and intraoperative pain during endodontic treatment and that patients with higher anxiety may report more intense intraoperative pain [20,21]. However, RCT fear cannot be reduced to anticipated pain alone. Local anesthetic injection, the sensation of endodontic files, instrument sounds, prolonged mouth opening, pressure applied to a sensitive tooth, postoperative symptoms, and the possibility of treatment failure may also act as endodontic-specific fear triggers [11,22].

Several instruments are used to measure dental anxiety, including the Dental Anxiety Scale, Modified Dental Anxiety Scale, Dental Fear Survey, and visual analog scales [1,23,24]. These instruments are clinically useful; however, total scores may not always identify the specific stimuli that drive an individual patient's fear [8,22]. The Visual Analog Scale for Anxiety (VAS-A) is a practical single-item measure for preoperative anxiety because it is quick and easy to administer at the chairside [25,26,27]. In this study, the VAS-A was used as a measure of situational preoperative anxiety severity rather than as a diagnostic criterion for dental phobia.

Most studies of endodontic anxiety have examined total anxiety scores, general dental anxiety instruments, or changes in anxiety before and after treatment [20,21,28,29]. Although valuable, this approach may incompletely represent patient-level heterogeneity in RCT fear. Two patients with similar total anxiety scores may fear RCT for different reasons. One patient may be primarily needle-focused, whereas another may fear a combination of pain, prolonged mouth opening, instrument sensations, sounds, and treatment failure. This distinction is important because different fear contents may require different communication and anxiety-management strategies [8,22,30].

Person-centered analytic approaches provide an appropriate framework for examining this heterogeneity. Whereas variable-centered analyses estimate relationships among variables, person-centered profile analyses group individuals with similar response patterns, thereby identifying clinically recognizable patient types [30]. In this study, hierarchical clustering and latent class analysis (LCA) were used as complementary methods. Hierarchical clustering addressed the question “How much does the patient fear RCT?”, whereas LCA addressed “Why does the patient fear RCT?”

The primary aim of this cross-sectional study was to identify clinically interpretable RCT fear profiles based on fear severity and trigger content among adults scheduled for primary RCT and to examine the associations of these profiles with dental attendance, postponement of dental visits, previous negative RCT experiences, and family/social and media exposures. We hypothesized that RCT fear would form distinct profiles according to both severity and trigger content.

2. Materials and Methods

This single-center, cross-sectional, structured questionnaire-based observational study was conducted among adult patients who presented to the Department of Endodontics, Faculty of Dentistry, Selçuk University, and were scheduled for primary RCT. Data were collected between 1 April 2025 and 1 April 2026. Reporting was structured in accordance with the STROBE recommendations for cross-sectional observational studies [31].

Eligible patients were enrolled consecutively during the predefined data-collection period. The inclusion criteria were presentation to the endodontic clinic; a clinical and radiographic indication for primary RCT; age 18-60 years; ability to read and understand Turkish; ability to complete the questionnaire independently before treatment; and provision of written informed consent. Both symptomatic and asymptomatic patients were eligible, provided that a primary RCT was planned.

Before questionnaire administration, patients were assessed for eligibility. Patients scheduled for retreatment of a previously root-filled tooth, those outside the predefined age range, those with cognitive or communication limitations preventing independent questionnaire completion, those who had previously participated in the study, and those presenting for a procedure other than primary RCT were not enrolled and did not receive the questionnaire. The recruitment count was restricted to patients scheduled for primary RCT; other patients treated in the clinic were outside the study population.

During the study period, 425 patients scheduled for primary RCT were invited to participate. Of these, 247 (58.1%) provided written informed consent and completed the questionnaire, whereas 178 declined participation. Questionnaires were excluded from the analysis if they contained missing responses required for the principal analyses or internally inconsistent responses. Six questionnaires were incomplete and 22 contained internally inconsistent responses. Internal inconsistency was defined as mutually incompatible answers to logically related items, such as reporting no fear of RCT while selecting one or more RCT fear triggers or reporting no previous RCT experience while evaluating a previous RCT experience. Thus, 28 questionnaires met the data-quality exclusion criteria, resulting in a final analytical sample of 219 participants.

Sample size was determined by an a priori power analysis for the chi-square test of independence. Assuming a medium effect size (Cohen's w = 0.25), α = 0.05, and 90% power, the minimum required sample size was 203. With 219 participants included, the achieved power was 92.2%. The analysis was performed using G*Power 3.1.9.7.

All participants received verbal and written information about the study and provided written informed consent before participation. Personal data were processed anonymously and used solely for scientific research. The study was approved at the meeting of the Non-Interventional Clinical Research Evaluation Committee of the Faculty of Dentistry, Selçuk University, held on 10 March 2025 (approval no. 2025/26).

Participants who met the eligibility criteria completed a structured questionnaire before the RCT. The form was provided by a study investigator before treatment and completed without guidance from the clinician who would perform the procedure. Only technical instructions on how to mark responses were given; no explanation that could influence response content was provided. This procedure was used to reduce bias related to interviewer and clinician influence.

The questionnaire recorded sex, age group, educational level, self-reported regular dental attendance, postponement of dental visits, reasons for postponement, the dental procedure perceived as most frightening, fear associated with the thought of visiting a dentist, fear associated with sitting in the dental chair, previous RCT experience, RCT-related fear triggers, negative RCT experiences in childhood and adulthood, negative RCT experiences among family members or in the social environment, exposure to negative media information about RCT, and preoperative anxiety.

The questionnaire content was developed from items and concepts used in the literature on general dental anxiety and endodontic fear. Items concerning the thought of visiting a dentist and sitting in the dental chair were consistent with the anticipatory and clinical-setting components emphasized in the DAS/MDAS tradition [1,24]. Endodontic-specific triggers were adapted from the Endodontic Fear Survey and Dental Fear Survey and included local anesthetic injection, fear of pain during treatment, postoperative pain, postoperative swelling, instrument sounds, the sensation of endodontic instruments, prolonged mouth opening, and the possibility of treatment failure [22,23].

Preoperative anxiety was assessed immediately before treatment using the Visual Analog Scale for Anxiety (VAS-A). Participants marked their current preoperative fear/anxiety level on a 0-10 cm visual analog line, and the marked distance was recorded in centimeters. VAS-A scores were classified according to the cutoffs proposed by Facco et al. [26]: 0-5.0 cm, no anxiety; 5.1-6.9 cm, dental anxiety; and ≥7.0 cm, severe dental anxiety.

Sociodemographic variables comprised sex, age group, and educational level. Dental behavior variables included self-reported regular dental attendance, postponement of dental visits, and reasons for postponement. RCT-specific variables comprised previous RCT, RCT-related fear, and specific fear triggers. The RCT-related fear variable was derived by distinguishing participants who selected “no fear” on the trigger list from those who selected at least one RCT fear trigger. Fear triggers were coded as dichotomous multiple-response items: injection/needle, fear of pain during treatment, fear of postoperative pain, fear of postoperative swelling, instrument sounds, sensation of endodontic instruments, prolonged mouth opening, and possibility of treatment failure. Sources of negative experience/exposure were summarized as negative RCT experience in childhood, in adulthood, among family members/in the social environment, and in media exposure. The cumulative number of negative sources was calculated by summing these sources.

Statistical Procedures

Categorical variables were summarized as frequencies and percentages. Relationships between categorical variables were examined using cross-tabulations. Pearson's chi-square test was used when assumptions were met, and Fisher's exact test was used for sparse contingency tables or when expected cell counts were insufficient. The significance threshold was set at p < 0.05. Cramer's V was reported as an effect-size measure for selected chi-square tests. Statistical analyses were performed using IBM SPSS Statistics 24.0, jamovi 2.4, Microsoft Excel 2016, and RStudio 2023.09.0.

Fear-severity profiles were identified using hierarchical cluster analysis. The analysis was intended to classify participants by their overall pattern of fear severity rather than by individual variables. The following indicators were included: fear associated with the thought of visiting a dentist, fear of sitting in the dental chair, RCT-related fear, number of RCT fear triggers, overall fear associated with the thought of undergoing RCT, and VAS-A classification. Because the variables were measured on different scales, they were standardized. Euclidean distance was used as the distance metric, and Ward's method was used for clustering [32]. The two-cluster solution was selected based on inspection of the dendrogram, separation of fear-severity indicators, cluster size, and clinical interpretability.

Fear-content profiles were examined using LCA among participants who reported RCT-related fear (n = 166). LCA estimates unobserved subgroups from observed dichotomous response patterns and is appropriate for binary trigger indicators. Eight dichotomous fear triggers were included. Two- and three-class models were compared using log-likelihood, Akaike information criterion (AIC), Bayesian information criterion (BIC), entropy, estimated class proportions, class size, and clinical interpretability. Thirty random starts, 5000 iterations, and a convergence tolerance of 1 × 10−8 were used. BIC was treated as the primary parsimony criterion, while AIC, entropy, class size, and clinical coherence were considered jointly as secondary criteria. The two-class solution was retained because it had the lower BIC and yielded two clinically interpretable classes without introducing the small additional class observed in the three-class solution. Participants were assigned to the class with the highest posterior membership probability for subsequent cross-tabulations; model-estimated class proportions and modal assignment counts were reported separately. Class labels were descriptive and were not intended to represent diagnostic categories. Fear of pain during RCT was interpreted as a fear trigger rather than as a measure of actual pain intensity.

3. Results

3.1. Participant Characteristics and Dental Attendance

Among 425 patients scheduled for primary RCT and invited to participate, 247 (58.1%) consented and completed the questionnaire, whereas 178 declined participation. Of the 247 questionnaires, 6 were excluded for incomplete responses and 22 for internally inconsistent responses, resulting in a final analytical sample of 219 participants. The sex distribution was balanced: 109 participants were women (49.8%) and 110 were men (50.2%). The largest age groups were 26-35 years (28.3%) and 18-25 years (25.6%). Most participants had a high-school or university-level education. The participant flow is shown in Figure 1.

Only 33.8% of participants reported regular dental attendance, whereas 66.2% reported that they did not attend regularly. Similarly, 66.2% reported postponing a dental visit despite knowing it was necessary. The most common reasons for postponement were lack of time, absence of pain or tolerable pain, and fear/anxiety. Tooth extraction (43.8%) and RCT (42.5%) were reported at nearly equal rates as the most frightening dental procedures. Participant characteristics, dental attendance behaviors, and key RCT fear variables are summarized in Figure 2.

Among the 166 participants reporting RCT-related fear, the most frequently reported trigger was fear of pain during treatment (n = 74, 44.6%), followed by injection/needle fear (n = 58, 34.9%), prolonged mouth opening (n = 47, 28.3%), postoperative pain (n = 30, 18.1%), the possibility of treatment failure (n = 26, 15.7%), sensation of endodontic instruments (n = 22, 13.3%), instrument sounds (n = 20, 12.0%), and postoperative swelling (n = 13, 7.8%). Multiple responses were permitted.

The frequency of RCT-related fear was similar among patients with and without previous RCT experience (76.4% vs. 74.2%; p = 0.727), but the distribution of reported triggers differed (p = 0.044). Fear of pain during treatment (40.3% vs. 31.2%) and postoperative pain (19.4% vs. 11.5%) were more frequently reported by patients without previous RCT experience, whereas instrument sounds (12.1% vs. 1.6%) and prolonged mouth opening (24.8% vs. 12.9%) were more frequently reported by those with previous RCT experience.

3.2. RCT Fear Burden, VAS-A Classification, and Sources of Negative Experience/Exposure

According to the VAS-A classification, 130 participants (59.4%) had no preoperative anxiety, 41 (18.7%) had dental anxiety, and 48 (21.9%) had severe dental anxiety. Overall, 40.6% of participants were classified as having dental anxiety or severe dental anxiety.

Severe dental anxiety was identified in 35.8% of women (39/109) and 8.2% of men (9/110) (χ² = 31.05, p < 0.001).

The number of RCT fear triggers showed a graded relationship with VAS-A classification. Severe dental anxiety was present in only 1.9% of participants who reported no RCT fear trigger, increasing to 18.4% among those reporting one trigger, 30.3% among those reporting two triggers, and 54.3% among those reporting three or more triggers (χ² = 69.21, p < 0.001; Cramer's V = 0.40).

Sources of negative experience/exposure also showed a graded relationship with VAS-A classification. Severe dental anxiety was identified in 9.3% of participants who reported no negative source, 26.3% of those who reported one source, and 50.0% of those who reported two or more sources (χ² = 30.15, p < 0.001; Cramer's V = 0.26). VAS-A classification according to sex, number of RCT fear triggers, and number of sources of negative experience/exposure is presented in Figure 3.

A negative RCT experience in childhood was reported by 28 participants (12.8%), a negative RCT experience in adulthood by 54 (24.7%), a negative RCT experience among family members or in the social environment by 50 (22.8%), and negative media exposure by 23 (10.5%). Among participants who reported the respective source, the proportions who stated that the experience or exposure contributed to their current RCT fear were 57.1% (16/28), 61.1% (33/54), 54.0% (27/50), and 78.3% (18/23), respectively.

3.3. Patient Profiles by Fear Severity

When fear associated with the thought of visiting a dentist, sitting in the dental chair, overall RCT fear, number of reported triggers, and preoperative anxiety were considered together, participants were separated into two distinct groups. The low-fear profile comprised 120 patients, among whom fear related to the dental setting and RCT generally remained low, and the number of reported RCT fear triggers was limited. The high-fear profile comprised 99 patients, among whom fear was more pronounced across all assessments, from the thought of visiting a dentist and sitting in the dental chair to RCT-specific triggers.

The clinical characteristics of the high-fear profile differed from those of the low-fear profile. Women constituted 69.7% of the high-fear profile, and only 25.3% reported regular dental attendance. Postponement of dental visits occurred in 78.8% of the high-fear profile and 55.8% of the low-fear profile. A negative RCT experience in adulthood was also more common in the high-fear profile (35.4% vs. 15.8%). Negative RCT experience in childhood was numerically more frequent in the high-fear profile, but the difference was not statistically significant.

Age distribution also differed between the two profiles (χ² = 9.88, p = 0.042). In the high-fear profile, the 26-35- and 36-45-year age groups accounted for 34.3% and 24.2%, respectively, whereas the 46-55- and 56-60-year groups each accounted for 8.1%. The profile-defining indicators and selected external associations of the fear-severity profiles are shown in Figure 4.

3.4. Profiles of RCT Fear by Trigger Content

Fear-content profile analysis was conducted among 166 participants who reported at least one RCT fear trigger. The low- and high-fear profiles described in Section 3.3 represent fear severity, whereas the latent classes in this section represent fear content. Model-selection indices gave conflicting signals. The three-class solution had a lower AIC than the two-class solution (1273.54 vs. 1287.62) and higher entropy (0.948 vs. 0.833), whereas the two-class solution had a lower BIC (1340.53 vs. 1354.45; ΔBIC = 13.92 in favor of the two-class model). The three-class solution also contained a small, estimated class comprising 12.4% of the sample (approximately 21 participants). Because BIC was designated as the primary parsimony criterion and the additional class did not provide a sufficiently distinct clinical interpretation to offset the added complexity, the two-class solution was retained. This should be regarded as a parsimonious exploratory choice rather than evidence that only two latent classes can exist. Panel A of Table 1 presents the model comparison.

In the retained model, the estimated class proportions were 17.7% and 82.3%, whereas classification by maximum posterior probability yielded 38 (22.9%) and 128 (77.1%) participants. This difference is expected because estimated proportions are probabilistic model parameters, whereas modal assignment assigns each participant to the single class with the highest posterior probability. Modal assignments were used for the external comparisons reported in Section 3.5.

The smaller modally assigned class comprised 38 patients and was labeled the needle-focused profile because endorsement was concentrated on injection/needle fear. The model estimated an item-response probability of 1.000 for injection/needle fear, compared with 0.147 for fear of pain during treatment and 0.046 for postoperative pain; the remaining procedural triggers had boundary estimates of 0.000. The larger class comprised 128 patients and was labeled the procedural fear profile because endorsement extended across several stages of RCT. Its highest item-response probabilities were fear of pain during treatment (0.510), prolonged mouth opening (0.344), injection/needle fear (0.217), postoperative pain (0.210), and treatment failure (0.190), with lower probabilities for instrument sensation, instrument sounds, and postoperative swelling. The labels summarize relative response patterns rather than fixed clinical phenotypes. In particular, the 1.000 and 0.000 estimates in the smaller class are boundary estimates and should be interpreted cautiously, given the class size and exploratory design. Panel B of Table 1 presents the item-response probabilities for the retained two-class solution.

3.5. Clinical and Experiential Characteristics of Fear-Content Profiles

To determine whether the two fear-content profiles differed beyond the trigger patterns used to define them, external characteristics were examined in three conceptually distinct domains: the clinical expression of RCT fear, negative RCT experiences, and indirect experiences or exposures. The comparisons in this section were restricted to variables that describe the clinical or experiential meaning of the profiles.

The needle-focused and procedural fear profiles showed similar overall clinical expression. The distributions of fear elicited by the thought of undergoing RCT and VAS-A classification did not differ between the profiles (p = 0.915 and p = 0.693, respectively). Severe dental anxiety was observed in 23.7% of the needle-focused profile and 29.7% of the procedural fear profile.

Among negative experiences, a childhood negative RCT experience was reported more frequently in the procedural fear profile than in the needle-focused profile (17.2% vs. 2.6%; p = 0.042). This finding should be interpreted cautiously because only one participant in the needle-focused profile reported such an experience. Negative RCT experiences in adulthood did not differ between the profiles (p = 0.128). Likewise, the distributions of negative RCT experiences among family members or within the social environment and negative media exposure were comparable (p = 0.379 and p = 0.245, respectively). Overall, the profiles were distinguished primarily by the content of fear rather than by its overall intensity or by most measured experiential characteristics. The complete comparisons are presented in Table 2.

4. Discussion

This study shows that RCT fear cannot be explained by a single severity indicator. Hierarchical clustering distinguished low- and high-fear patterns, whereas LCA distinguished needle-focused and procedural fear content. The proportion with severe dental anxiety increased as the number of fear triggers and sources of negative experience/exposure increased; the high-fear profile was associated with female sex, irregular dental attendance, postponement of dental visits, and a negative RCT experience in adulthood. Taken together, these findings indicate that RCT fear is a multidimensional construct encompassing severity, content, experience, and avoidance behavior.

These findings broadly support the working hypothesis that RCT fear is not homogeneous and forms clinically interpretable patterns based on both severity and trigger content. However, given the exploratory nature and model sensitivity of the LCA solution, the content-based component of this hypothesis should be regarded as provisionally supported.

One of the most distinctive findings was that the needle-focused and procedural fear profiles did not differ in overall RCT fear or VAS-A distributions. In other words, these profiles did not separate patients who were afraid; they separated patients who feared different aspects of treatment despite similar anxiety severity. This finding indicates that fear severity and fear content are not interchangeable and that the two person-centered analyses characterize the same clinical condition from different perspectives.

Most measured negative RCT experiences and indirect exposures also showed similar distributions across the two fear-content profiles. The only observed difference was a higher frequency of negative childhood RCT experience in the procedural fear profile; however, this comparison was based on a single affirmative response in the needle-focused profile and should therefore be interpreted cautiously. This pattern suggests that the profiles primarily distinguish the content of fear rather than defining stable etiological groups based on previous experiences or exposures.

The high-fear profile was not a narrow group defined solely by high VAS-A values. These patients reported more pronounced fear at the thought of visiting a dentist and sitting in the dental chair, a greater number of RCT triggers, less frequent regular dental attendance, and more frequent postponement behavior. The greater frequency of negative RCT experience in adulthood in this profile indicates that high fear represents a broader clinical pattern accompanied by adverse treatment history and avoidance behavior. This relationship is consistent with the fear-avoidance cycle that links dental fear with service use [7,8]; however, the cross-sectional design does not permit determination of the direction of the relationship.

The proportion with severe dental anxiety was approximately four times higher among women than men (35.8% vs. 8.2%), and women were more strongly represented in the high-fear profile. This finding is consistent with previous studies reporting higher levels of dental fear and anxiety among women [2,5,6,33]. Although the high-fear profile was more frequent in the 26-45-year age range, VAS-A classification did not differ across age groups. The age finding should therefore be regarded as an exploratory association with the composite fear pattern rather than as a general age effect.

The graded relationship between trigger count and dental anxiety was marked: the proportion with severe dental anxiety increased from 1.9% among participants reporting no trigger to 54.3% among those reporting three or more triggers. Similarly, this proportion increased from 9.3% among those reporting no source of negative experience/exposure to 50.0% among those reporting two or more sources. These findings indicate that high anxiety is associated not with a single fear element but with the co-occurrence of multiple triggers and negative sources within the same patient [8,13,14,15,34]. Nevertheless, no causal inference can be made that such accumulation increases anxiety.

Sources of negative experience and exposure do not represent the same psychological pathway. Personal negative RCT experiences may be considered within a direct-conditioning framework; experiences conveyed by family or the social environment through observational learning; and media content through verbal and indirect pathways of fear acquisition [8,11,13,14,15]. More than half of those reporting negative experiences in childhood, adulthood, or the social environment stated that these experiences contributed to their current fear. Although negative media exposure was less frequent (10.5%), 78.3% of the 23 exposed patients stated that such content contributed to their current fear. Because this proportion is based on the retrospective subjective assessment of a small subgroup, it does not demonstrate that the media caused the fear or exerted a stronger influence than other sources.

Previous RCT experience was not associated with the overall frequency of RCT fear or VAS-A level; however, fear content differed according to experience. Anticipated pain during and after the procedure was more prominent among patients without previous RCT experience, whereas instrument sounds and prolonged mouth opening were more frequently reported by experienced patients. This distinction suggests that not only the presence of experience but also the procedural elements with which it is remembered may be important [17,18,19,22,35]. However, because of the multiple-response structure and cross-sectional design, this pattern should not be interpreted as a causal learning effect.

The nearly equal proportions of participants selecting tooth extraction and RCT as the most frightening dental procedure are also noteworthy. Although RCT is intended to preserve the tooth, its perception as frightening as extraction suggests it remains associated in patients' minds with pain, threat, procedural duration, and uncertainty. This finding is consistent with previous studies reporting that RCT is perceived as a painful or anxiety-provoking procedure [16,17,22,35,36].

The functions of the measurements used should be distinguished when interpreting the findings. The VAS-A assessed the severity of situational preoperative anxiety, whereas the structured form assessed fear related to the dental setting, endodontic-specific triggers, sources of negative experience, and avoidance behavior. Items concerning the thought of visiting a dentist and sitting in the dental chair were consistent with the anticipatory and clinical-setting dimensions in the DAS/MDAS tradition; endodontic-specific triggers were consistent with the DFS, Endodontic Fear Survey, and studies of RCT perceptions [1,17,22,23,24,35]. This structure allowed fear level and content to be examined within the same framework but as separate dimensions. Although Facco et al. [26] associated the ≥7.0 cm threshold with phobic dental anxiety, dental phobia requires clinical evaluation of persistence, disproportionality, avoidance, and functional impairment [3,4]. Accordingly, this category was used as a non-diagnostic label of “severe dental anxiety” in the present study.

The principal limitations of the study are its single-center, cross-sectional design and the retrospective, self-reported assessment of prior experiences. The fear-content solution should also be regarded as exploratory. Model-selection criteria were not unanimous: AIC and entropy favored the three-class solution, whereas BIC favored the two-class solution. The retained two-class model included a smaller needle-focused class; model-estimated and modally assigned class proportions did not coincide, and several item-response probabilities reached boundary values of 0.000 or 1.000. These features indicate potential sensitivity in the sample and require replication in larger, independent samples before the classes are treated as stable clinical subtypes. The trigger distributions according to previous RCT experience were derived from multiple-response data and should therefore be interpreted cautiously. The observed associations should not be interpreted as evidence of causality, and no conclusions should be drawn regarding the psychometric validity of the form.

Overall, the findings indicate that the severity of RCT fear, its dominant trigger, sources of negative experience, and dental avoidance behavior are related but non-interchangeable dimensions. The person-centered approach shows that patients with similar anxiety levels may have different fear contents and that the same level of fear may be shaped by different experiential pathways. This distinction is fundamental to a more accurate clinical and research characterization of RCT fear.

Future studies should evaluate the reproducibility and stability of these fear profiles in larger, multicenter, and independent samples. Prospective longitudinal designs are also needed to clarify the temporal relationships among negative experiences, fear severity, trigger content, and avoidance behavior. Further research should additionally examine whether brief trigger-focused screening and profile-tailored anxiety-management strategies improve patient experience, treatment attendance, and clinical outcomes.

5. Conclusions

Among adult endodontic patients, RCT fear showed distinct patient patterns in both overall severity and dominant trigger content. Severity-based analysis separated patients into low- and high-fear profiles, whereas trigger-content analysis identified needle-focused and procedural fear profiles. These two classifications represent complementary but distinct dimensions of RCT fear.

The finding that patients with similar anxiety levels may fear different aspects of treatment indicates that total anxiety severity alone does not adequately characterize the structure of a patient's fear. In some patients, fear was concentrated on injections and needles; in others, anticipated pain, prolonged mouth opening, instrument sensations and sounds, postoperative symptoms, and the possibility of treatment failure occurred together. The proportion with severe dental anxiety also increased as the number of reported fear triggers and sources of negative experience or exposure increased.

The high-fear profile was associated with female sex, irregular dental attendance, postponement of treatment, and negative RCT experience in adulthood. These findings indicate that RCT fear should be evaluated not by a single anxiety score alone, but through a combined assessment of fear severity, specific triggers, previous experiences, and dental attendance behavior.