Changes in heart rate during third molar surgery


Anxiety is an undesirable psychological phenomenon. Patients are usually anxious when subjected to third molar surgery, but the pattern of anxiety is unknown. The aim of this study was to assess the intensity and course of anxiety during third molar surgery. This study included 48 consecutive patients (mean age 25 ± 6 years) who had a third molar removed surgically under local anaesthesia. The heart rate was monitored continuously during treatment as a measure of anxiety. Preoperative anxiety was scored with the Modified Dental Anxiety Scale. Each patient’s anxiety level was assessed when in the waiting room, sitting down in the dental chair, during the application of local anaesthesia, application of surgical drapes, time-out procedure, incision, alveolotomy, removal of the third molar, and suturing, and at the end of the procedure. The lowest heart rates were recorded in the waiting room, in the dental chair, during anaesthesia, when applying surgical drapes, during suturing, and at the end of the procedure. The highest values were obtained during the time-out procedure, incision, and alveolotomy ( P < 0.005). In conclusion, the intensity and course of anxiety has a specific pattern during third molar surgery, with the lowest levels of anxiety prior to surgery and directly postoperative and the highest during the time-out procedure and the actual surgery.

Moderately to highly anxious patients experience more intense and prolonged postoperative pain and higher psychological co-morbidity when subjected to surgery. Amongst the many variables that affect the threshold for pain, anticipation and anxiety have been reported to be the most important.

Numerous procedures have been shown to provoke anxiety, such as sigmoidoscopy, colposcopy, percutaneous coronary interventions, and cardiac surgery. Anxiety most often peaks prior to the procedure and decreases immediately after the procedure. Whether this pattern also applies to oral surgery, e.g., removal of a third molar, is not yet known, although it has been reported that oral surgery is linked to specific and intensive fear. Furthermore, about 50% of patients are anxious about dental treatment. A visit to the dental clinic provokes feelings of anxiety, and increases blood pressure and heart rate.

Anxiety assessments have indicated a higher level of treatment anxiety for oral and maxillofacial surgery than for dental treatment. Therefore, the results of dental studies cannot be translated directly to oral and maxillofacial practice. The course of anxiety throughout the process of third molar removal has not been evaluated thoroughly. Therefore, the aim of this study was to assess the intensity and course of anxiety during oral and maxillofacial surgery treatments. This was done by measuring real-time heart rate changes before, during, and after the surgical removal of a third molar, as well as measuring the accompanying fear with the Modified Dental Anxiety Scale (MDAS). Detailed knowledge of the level and course of anxiety accompanying surgical third molar removal may help in identifying anxiety-reducing interventions.

Materials and methods


All consecutive patients seen during a 6-week period who were scheduled for the removal of a third molar under local anaesthesia and who were eligible when assessed against the study inclusion and exclusion criteria, were asked to join the study. Inclusion criteria encompassed patients with an indication for the removal of a lower third molar under local anaesthesia, aged between 18 and 40 years, and who were fluent in the Dutch language (to be able to complete the questionnaire). Exclusion criteria were a third molar removal or other oral or maxillofacial procedure within the past 6 months, medical conditions and the use of medications that may induce alterations in heart rate, and patients with an implanted pacemaker or implantable cardioverter defibrillator (ICD).

Study design

Ten minutes before surgery, the preoperative dental anxiety level (situation-specific trait anxiety) was estimated using the validated Dutch version of the MDAS. The MDAS consists of five questions, each with a five-category rating scale ranging from ‘not anxious’ to ‘extremely anxious’. Patients rated their emotional reaction during the anticipation of an appointment at the dental clinic, when in the waiting room, and in anticipation of drilling, scaling, and local anaesthetic injection. Responses were scored from 1 to 5, providing total scores ranging from 5 (not anxious at all) to 25 (extremely anxious). Dental anxiety scores of 19 or higher were considered as indicative of high dental trait anxiety.

After completing the questionnaire, the patient’s heart rate was recorded continuously until the end of the procedure using a Mio Alpha watch (Mio Alpha; Mio Global Physical Enterprises Inc., Vancouver, British Columbia, Canada), a watch with an accuracy comparable to the accuracy of an electrocardiogram (ECG). The real-time heart rate data were transmitted to a Bluetooth Smart Android operated pad. The electronics of the Alpha Mio watch are integrated into the back plate of the wristband and include an accelerometer enabling electro-optical cells to detect the pulsing volume of blood flow (photoplethysmography).

The study was approved by the hospital medical ethics commission. Informed consent was obtained from all patients prior to the study.

Pre-surgical procedure

All consecutive patients who were eligible after application of the inclusion/exclusion criteria were asked to participate when they were scheduled for surgery. After obtaining informed consent, each patient had to complete the MDAS questionnaire, and demographic data were recorded (age, sex, medical history, use of medication, etc.). Next, the patient’s heart rate was measured using the continuous heart rate monitor. A Bluetooth link was established with an android tablet using the Bluetooth Low Energy heart rate monitor application (BLE Heart Rate Monitor; Pribble Software LLC, Germantown, Maryland, USA). This monitored and recorded the heart rate every second. The application recorded how much time had elapsed since the start of the heart rate measurements. The time elapsed was also scored on a form and was kept during the various stages of the surgical procedure. These stages were the moment the patient took a seat in the waiting room, when sitting down in the dental chair, the moment of application of local anaesthesia, application of the surgical drapes over the patient’s face, time-out procedure, moment of incision, alveolotomy, removal of the third molar, suturing, and the end of the procedure ( Table 1 ). After the patient had been connected to the heart rate monitor, the patient returned to his/her seat in the waiting room where they had to wait for at least 5 min. Subsequently, the patient was accompanied to the operating room and settled in the dental chair. The patient received routine verbal information and reassurance from the operating surgeon.

Table 1
Description of the heart rate measurement time periods.
Period Measurement time point
1 In the waiting room
2 In the dental chair
3 During local anaesthesia
4 During the application of surgical drapes
5 During the time-out procedure
6 During incision
7 During alveolotomy
8 During removal of the third molar
9 During suturing
10 At the end of the procedure
Pain During pain
Additional anaesthetics During the administration of additional anaesthesia

Surgical procedure

The two senior oral and maxillofacial surgeons were familiar with the aim of this study. The surgical procedure was standardized. In short, the surgical field was anaesthetized by mucosal infiltration and blocking of the inferior alveolar nerve with two to three carpules of local anaesthetic (40 mg articaine hydrochloride per millilitre (4%), with 0.01 mg epinephrine; 1.7 ml per carpule). After local anaesthesia, the surgical field was isolated with sterile drapes, leaving the patient’s nose and mouth exposed. The time-out protocol followed, which consisted of the verification of the patient’s identity and the aim of the procedure. This time-out procedure is a ‘second time’ time-out procedure. In the study clinic, the patient’s data are checked as soon as the patient is called in from the waiting room. After checking the anaesthetic state of the mucosa, the surgeon made an incision and created a mucoperiosteal flap. After alveolectomy, when necessary, the third molar was removed and the flap was repositioned and sutured. After surgery, routine postoperative instructions, including the use of ibuprofen, were provided to the patient. Subsequently, the Mio Alpha watch was disconnected.

Statistical analysis

A power analysis with a power of 90% and a two-sided significance level of 0.005 was used (with 10 tests as the primary outcome, for the 10 time periods; see Table 1 ). The significance level of 0.005 was used because the Bonferroni correction was necessary, as 10 tests were used as the primary outcome. Calculations of the sample size were based on paired-samples t -tests, in which a non-parametric analysis was taken into account by adding 10% to the total sample size. Sample size calculations were performed using SamplePower 2.0 (SPSS Inc., Chicago, IL, USA).

A significant change in heart rate of 10 beats per minute (bpm), with a standard deviation of the paired difference of 10.7 (based on a standard deviation of 12 bpm and a correlation between the paired observations of r = 0.6), resulted in a minimum calculated sample size of 25. By adding 10% for the possibility of non-parametric testing, the sample size required was 27.5. Another 10% was added for the attrition rate. This resulted in a minimum sample size of 31 patients to be collected during the 6-week patient inclusion period.

The data were processed in two different ways. The first approach consisted of selecting 15 s of heart rate measurements before and 15 s after the moment of onset of an event. This approach was used in order to investigate the impact of an individual event on the heart rate of a participant. An interval of 30 s around a specific event was estimated to be representative. The second approach was limited to an interval of 15 s of heart rate measurements after the onset of an event. This time-period directly after the onset of an event was considered as representative of the heart rate during that event. This approach was chosen to compare the different events to each other and to determine whether any differences in heart rate occurred between the events during the whole treatment process.

Data were analyzed using IBM SPSS Statistics version 22.0 (IBM Corp., Armonk, NY, USA). The Shapiro–Wilk test, Kolmogorov–Smirnov test, and graphical interpretation of normal Q–Q plots were used to determine the distribution of the data. If the data did not appear to be normally distributed, transformation was applied in order to obtain a normal distribution. Where applicable, paired- or independent-samples t -tests, Wilcoxon signed-rank tests, Friedman tests with post hoc testing, and Mann–Whitney U -tests were applied. With the Bonferroni correction taken into account, each individual hypothesis was tested at α = 0.005.


Within the recruitment period of 6 weeks, 53 participants were eligible to join the study. All patients were willing to participate. Of these 53 patients, two had to be excluded from the final analysis due to an alternative treatment, one patient because of a vasovagal collapse during treatment, one anxious patient because she persisted in removing the sterile drapes from her face, and one patient because of an extremely high heart rate (209 bpm). In this latter case, surgery was temporarily stopped to assess the stability of the patient. The remaining 48 patients, ranging in age from 18 to 40 years (mean 25 ± 6 years), were included in the data analysis; 20 were men (mean age 25 ± 7 years) and 28 were women (mean age 24 ± 5 years). Thirty-six (75%) of the participating patients had a mandibular third molar removed and 12 (25%) had a combination of maxillary and mandibular third molar removals on one side. Of the 48 participants, eight had pain complaints during treatment and needed additional anaesthetics. An alveolotomy was needed to remove the third molar in 31 out of the 48 participants.

Changes in heart rate during the course of third molar removal

All data, except data from the period ‘pain’ and the period ‘additional anaesthetics’, were not normally distributed. As transformation of the data did not result in a normal distribution, the Wilcoxon signed-rank test was used for the analysis of these data. The periods ‘pain’ and ‘additional anaesthetics’ were evaluated using paired samples t -tests.

A significant and sudden increase in heart rate occurred when the patient sat down in the dental chair (period ‘during dental chair’) and when the surgical drapes were put on the patient (period ‘during surgical drapes’, Fig. 1 ).

Dec 15, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Changes in heart rate during third molar surgery

VIDEdental - Online dental courses

Get VIDEdental app for watching clinical videos