Association Between Lingual Retraction and Hemodynamic Changes in Patients Receiving Dental Treatment Under General Anesthesia

A Prospective Observational Study on the Association of Lingual Retraction With Hemodynamic Parameter Changes in Patients Receiving Dental Procedures Under General Anesthesia

This study aims to investigate the association between sudden decreases in heart rate and blood pressure during dental procedures requiring lingual retraction-such as fillings, root canal treatments, tooth extractions, and cyst surgeries-under general anesthesia. Patients will be routinely monitored for vital parameters during anesthesia. Sudden drops in heart rate and blood pressure (10-20% decrease) will be recorded as lingual retraction-related trigeminocardiac reflex (TCR) events, along with the type of lingual retraction, dental procedure, and tooth location at the time of occurrence. Additionally, the results will be analyzed in relation to patient age, sex, and tongue size.

**Amendment [March 2026]:** Following protocol revision and ethics committee approval, the study population has been restricted to pediatric patients (aged 2-18 years), and the adult arm has been discontinued. The primary outcome and observational methodology remain unchanged; however, the secondary outcome regarding adult-pediatric comparison has been removed from the analysis plan.**

Study Overview

• Status: Completed
• Conditions: Hemodynamic Changes; Dental Procedures; Trigeminocardiac Reflex

Detailed Description

Stimulation of both the central and peripheral branches of the trigeminal nerve can lead to clinically significant hemodynamic changes. The trigeminocardiac reflex (TCR), a brainstem-mediated reflex mechanism triggered by such stimulations, causes sudden and marked decreases in heart rate and arterial blood pressure. This reflex may result in hemodynamic instability during surgical interventions and, in rare cases, can precipitate severe cardiac complications including cardiac arrest.

While TCR is more commonly observed during ophthalmic, craniofacial, and skull base surgeries, it may also occur during dental procedures. Stimulation of the peripheral branches of the lingual nerve, such as during lingual retraction, has been associated with cardiovascular side effects like bradycardia. This phenomenon reflects systemic hemodynamic responses resulting from trigeminal nerve stimulation.

The literature reports significant drops in heart rate and arterial pressure due to TCR during common dental procedures such as tooth extraction and implant surgery. Notably, sudden decreases of 10-20% in blood pressure are considered clinically relevant indicators of TCR. Additionally, hemodynamic changes potentially related to this reflex have been documented during endodontic treatments, particularly in cases of irreversible pulpitis. Thus, stimulation of the dental branches of the trigeminal nerve may trigger TCR during dental procedures, leading to systemic hypotension.

In conclusion, TCR triggered by trigeminal nerve stimulation is an important hemodynamic reflex encountered during surgical and dental interventions. Early recognition and appropriate preventive measures are critical to mitigating potential cardiac risks. Clinical procedures should consider patients' susceptibility to such reflexes in planning and management.

This study aims to investigate the incidence of trigeminocardiac reflex triggered primarily by lingual retraction, and secondarily by dental procedure type, tooth location, patient age, and duration of general anesthesia in **pediatric** patients undergoing dental surgeries under general anesthesia. **Statistical Revision & Amendment [March 2026]:** The study protocol has been revised to focus exclusively on the pediatric population (aged 2-18 years), in line with the primary research objective. The initial design included both adult (n=50) and pediatric (n=50) cohorts; however, the pediatric cohort was prioritized due to its greater susceptibility to trigeminocardiac reflex (TCR) events, and practical considerations regarding adult enrollment feasibility. Consequently, the adult arm was discontinued. This modification was reviewed and formally approved by the Kırıkkale University Non-Interventional Research Ethics Committee in its meeting on March 11, 2026 (2026/04 meeting number), referencing the original approval of the study (2025/12 meeting number, decision 2025.09.04). The primary outcome and data collection methodology from the original protocol were preserved, while the previously planned secondary outcome comparing adult and pediatric cohorts was removed. No other aspects of study design, observational methods, or ethical standards were modified.

Sample size calculations were performed using two complementary approaches. First, for multivariable analysis of potential predictors-including age, sex, anesthesia-related factors, and dental procedure characteristics (procedure type and the presence or absence of lingual retraction or tongue-base pressure)-sample size was calculated using the 'pwr' package in R Statistical Software (v4.5.2). Assuming a medium effect size (f² = 0.15), α = 0.05, and power = 0.80, the required total sample size was confirmed as N = 85.

Second, a proportion-based calculation was conducted to estimate the required pediatric sample size for detecting clinically relevant TCR-related hemodynamic responses (≥10% reduction in MABP). While prior literature reports a TCR incidence of approximately 52% in adults , a higher incidence of 70% was projected for pediatric patients due to their increased clinical sensitivity. The corresponding Cohen's h for this comparison was 0.34. This approach indicated that at least 68 participants would be required (α = 0.05, power = 0.80), but to ensure adequate statistical power across all analyses, the final sample size was set at N = 85.

Following the discontinuation of the adult cohort in March 2026, the statistical analysis plan was refined to prioritize a high-powered, single-cohort evaluation of the pediatric population. The removal of the adult-pediatric comparative analysis (previously a secondary objective) does not affect the internal validity of the primary outcome. All multivariable models and proportion-based estimates have been re-calibrated for the pediatric target sample of N=85, ensuring that the study remains adequately powered to identify key predictors of TCR events in this specific high-sensitivity group** Conducted at the operating rooms of Kırıkkale University Faculty of Dentistry, this prospective observational study will record TCR events using a specially designed patient monitoring form, correlating these events with various clinical factors.

• Study Type: Observational
• Enrollment (Actual): 85

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Kırıkkale, Turkey (Türkiye)
    • Kırıkkale University, Faculty of Dentistry

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

Patients undergoing dental procedures under general anesthesia at Kırıkkale University, Faculty of Dentistry, aged 2-18, classified as ASA physical status I or II. Pediatric patients will be included. Patients with cardiac or neurological conditions affecting the trigeminocardiac reflex will be excluded.

Description

Inclusion Criteria:

• Patients referred to our faculty for dental procedures requiring general anesthesia.
• Patients classified as ASA physical status I or II.

Exclusion Criteria:

• Patients unwilling to participate in the study.
• Patients classified as ASA physical status III or IV.
• Patients with diseases affecting cardiac inotropy, chronotropy, or dromotropy.
• Patients using medications influencing cardiac inotropy, chronotropy, or dromotropy.
• Patients with cardiac pacemakers.
• Patients with cardiac arrhythmias.
• Patients with neurological disorders affecting the trigeminocardiac reflex pathway (inhibition or activation).

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Group 1. Pediatric Patients; Patients aged 0 to 18 years undergoing dental procedures under general anesthesia. No intervention beyond routine clinical care; observational monitoring of trigeminocardiac reflex and hemodynamic parameters.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hemodynamic Changes Associated with Lingual Retraction	To quantify acute intraoperative alterations in heart rate and blood pressure related to lingual retraction during dental procedures performed under general anesthesia. Sudden decreases of ≥10-20% in these parameters will be defined and recorded as trigeminocardiac reflex (TCR) events.	During the dental procedure (up to 4 hours)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence and Characteristics of TCR Events	To determine the overall incidence of lingual retraction-related TCR events and to characterize their severity and duration, including the magnitude of hemodynamic change and the need for pharmacologic or mechanical interventions.	During the dental procedure (up to 4 hours)
Association of TCR Events With Procedural and Anatomic Factors	To evaluate the relationship between TCR occurrence and (a) the type of dental procedure (e.g., filling, root canal treatment, extraction, cyst surgery), (b) the method of lingual retraction, and (c) the treated tooth location (anterior/posterior; maxillary/mandibular).	During the dental procedure (up to 4 hours)
Influence of Patient Characteristics on TCR Occurrence	To investigate the association between patient-specific factors-such as age, sex, and tongue size-and the likelihood of developing TCR during lingual retraction under general anesthesia.	During the dental procedure (up to 4 hours)

Collaborators and Investigators

• Sponsor: Kırıkkale University

Publications and helpful links

General Publications

• Huang JI, Chang HH, Lin CP, Liao WC, Kao CT, Huang TH. Trigeminocardiac reflex during non-surgical root canal treatment of teeth with irreversible pulpitis. J Formos Med Assoc. 2018 Jun;117(6):512-517. doi: 10.1016/j.jfma.2017.05.010. Epub 2017 Jul 17.

Study record dates

Study Major Dates

• Study Start (Actual): October 13, 2025
• Primary Completion (Actual): March 27, 2026
• Study Completion (Actual): March 27, 2026

Study Registration Dates

• First Submitted: November 14, 2025
• First Submitted That Met QC Criteria: November 18, 2025
• First Posted (Actual): November 21, 2025

Study Record Updates

• Last Update Posted (Actual): April 9, 2026
• Last Update Submitted That Met QC Criteria: April 3, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: General Anesthesia; Hemodynamic Changes; Trigeminocardiac Reflex; Lingual Retraction; Dental Procedures
• Additional Relevant MeSH Terms: Mouth Diseases; Stomatognathic Diseases; Tongue Diseases; Glossoptosis
• Other Study ID Numbers: KU-ERKAN-003

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be publicly available but may be shared upon reasonable request with qualified researchers, subject to approval by the study team and compliance with ethical and confidentiality guidelines.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No