Patient anxiety and surgical difficulty in impacted lower third molar extractions: a prospective cohort study


Encountering patients who are fearful and anxious is common in dental practice and these factors can increase the complexity of dental procedures. A prospective cohort study was performed to assess whether patient anxiety influences the difficulty of impacted lower third molar extraction and to identify other predictive factors of surgical difficulty; 102 extractions done under local anaesthesia were assessed. Several preoperative variables were recorded (demographic, anatomical, and surgical) and patient anxiety was assessed through the use of various questionnaires. Extraction difficulty was measured using the operation time (OT) and a 100-mm visual analogue scale (difficulty VAS) completed by the surgeon. Patients with deep impacted third molars that required bone removal and tooth sectioning showed higher levels of preoperative anxiety. Significant correlations were found between questionnaire scores and the surgical difficulty (OT and difficulty VAS). OT was also related to age, depth of impaction, third molar angulations, proximity of the third molar roots to the mandibular canal, hard and soft tissue coverage, and the need to perform an ostectomy and tooth sectioning. Impacted lower third molar extraction is significantly more difficult in anxious patients. Other demographic, radiological, and surgical factors were also found to be significantly related to the surgical difficulty.

Encountering patients who are fearful and anxious is common in dental practice and these factors can increase the complexity of dental procedures. Dental anxiety is usually higher in tooth extractions, in procedures involving dental anaesthesia, and/or when rotary instruments are needed. For these reasons, the surgical extraction of impacted lower third molars is a procedure that will almost certainly involve some degree of anxiety in the patient.

Several preoperative variables have been identified that are significantly related to the surgical difficulty. Traditionally, oral surgeons have based this assessment mainly on the position of the third molar on panoramic radiographs. More recent studies have shown that patient demographic features such as age, gender, and race are also related to the surgical difficulty. However, these studies did not analyse patient anxiety, and in our opinion, this can be a very important variable with regard to lower third molar extraction difficulty, especially when local anaesthesia is used. The purposes of this study were to assess whether patient anxiety is related to the difficulty of extraction in impacted lower third molar removal and secondarily to identify other predictors of surgical difficulty.

Patients and methods

A prospective cohort study of 120 consecutively selected patients, who attended a university dental clinic for the extraction of an impacted lower third molar, was performed.

Inclusion criteria were (1) patient age between 18 and 45 years, and (2) no relevant systemic diseases (American Society of Anesthesiologists classification ASA I and ASA II). Patients who had undergone a previous third molar extraction, those who had a history of an unpleasant dental experience, and those taking anxiolytic medication or antidepressants were excluded from the study. The study protocol complied with the guidelines of the Declaration of Helsinki and was approved by the research ethics committee of the dental clinic. All patients signed an informed consent form agreeing to participate in the study. The STROBE guidelines for cohort studies were taken into consideration.

Variables and data measurement

A single researcher (LAA) collected the following variables: age, gender, body mass index (BMI), facial pattern, mouth opening, operated side, previous history of symptoms associated with third molar, Nolla stage, distal space and depth of impaction using the Pell and Gregory classification, position of the lower third molar according to the Winter classification, and degree of soft tissue and bone coverage. Additionally, the relationship of the third molar to the mandibular canal, following the radiological signs described by Rood and Shehab, was also recorded.

Two variables were used to measure the extraction difficulty: the operation time and a 100-mm difficulty visual analogue scale (VAS) completed by the surgeon after the surgical procedure. To rate anxiety, the patients were asked to complete several questionnaires (State–Trait Anxiety Inventory (STAI), Modified Dental Anxiety Scale (MDAS), Kleinknecht’s Dental Fear Survey (DFS), and Interval Scale of Anxiety Response (ISAR)) and the surgeon completed 10 VAS to assess the intraoperative behaviour of the patient ( Fig. 1 ).

Fig. 1
Assessment of intraoperative behaviour.

The STAI questionnaire consists of 40 questions divided into two groups, which assess anxiety as a transient state (state anxiety) and latent trait (trait anxiety). State anxiety is considered a transitory emotional state, characterized by subjective feelings, apprehension, and autonomic nervous system hyperactivity. Trait anxiety identifies relatively stable individuals with a tendency to perceive situations as threatening. In this study, the Spanish version published in 1982 was used.

The MDAS questionnaire is a modification of Corah’s Dental Anxiety Scale. It comprises five questions that measure anxiety at different stages of dental treatment. The maximum score is 25 and patients with a score of ≥19 points should be considered as very anxious. In the present sample, the Spanish version developed by Coolidge et al. was employed. Dental anxiety was also evaluated using the DFS questionnaire (Spanish version by Lago-Méndez et al. ), which consists of a total of 20 questions. The total score can range from 20 (no fear) to 100 (terrified), and a score of 63 is considered to be the cut-off point between subjects with or without dental anxiety. Finally, the patients were asked to draw a horizontal line over a vertical VAS of 90 mm (ISAR Spanish version ).

The subjects completed the trait STAI questionnaire to assess general anxiety at a separate appointment before being informed about the treatment. The remaining questionnaires (STAI state, ISAR, DFS, and MDAS) were completed by the patients in the same location, in a relaxed atmosphere, just before the surgical procedure.

Finally, after tooth extraction, the surgeon completed 10 VAS measuring intraoperative patient behaviour ( Fig. 1 ) and a postoperative evaluation sheet with several variables.

Surgical technique

All surgeries were performed by second year residents of a Master’s degree programme in oral surgery and implantology using a similar surgical technique. The extraction of impacted lower third molars was performed under local anaesthesia with articaine 4% and epinephrine 1:100,000 (Artinibsa; Inibsa, Lliça de Vall, Spain) and the patients were awake. The surgical field and all the surgical materials were sterile. The surgeon raised a full-thickness flap, which was protected by a Minnesota retractor. A lingual flap retraction using a Freer periosteal elevator was only performed when the surgeon consider it to be necessary. Sterile low-speed (20,000 rpm) hand pieces and sterile saline solution were used for bone removal and tooth sectioning when necessary. To close the wound, 3-0 silk sutures (Silkam; B. Braun, Tuttlingen, Germany) were used.

Sample size and statistical analysis

The sample size was calculated using the software G*Power 3.0 (Heinrich-Heine-Universität, Düsseldorf, Germany).

A descriptive and bivariate analysis was performed using SPSS v. 15.0 for Windows software (SPSS Inc., Chicago, IL, USA). Pearson correlations between anxiety variables (MDAS, DFS, STAI, ISAR, behaviour VAS) and extraction difficulty variables (operation time, difficulty VAS) were calculated. Correlations were also assessed between the different anxiety questionnaires. In addition, the MDAS and DFS questionnaire scores were analysed as binary variables (anxious and non-anxious, using the above mentioned cut-off scores). The level of significance was set at P < 0.05.


Initially 120 participants were enrolled in the study. However, 18 patients were excluded from the analysis because they did not report the day of surgery, or they were considered extremely anxious patients who required the surgical procedure to be carried out under intravenous conscious sedation.

The main clinical features of the patients can be seen in Table 1 . Statistically significant associations were found between the operation time and the following variables: depth of impaction (Pell and Gregory A, B, C), third molar angulations (Winter classification), radiological signs of proximity between the third molar roots and the mandibular canal, hard and soft tissue coverage, and the need to perform ostectomy and tooth sectioning. When the surgeons assessed the surgical difficulty, all these variables, as well as the distal space available (Pell and Gregory I, II, III) were also significant (difficulty VAS) ( Table 1 ). Age was correlated with the operation time and difficulty VAS ( Table 2 ; P < 0.01).

Table 1
Main clinical features of patients, and relationships with anxiety and surgical difficulty.
Variable Total sample MDAS DFS Behaviour VAS (mean) Difficulty VAS (mean) Operation time (mean)
≥19 ( n = 12) ≤18 ( n = 90) ≥63 ( n = 12) ≤62 ( n = 90)
Gender, male/female 49/53 4/8 45/45 4/8 45/45 15.8/19.9 39.3/36.1 27.8/25.3
Age, years 26 ± 6.6 28 ± 7.3 25.8 ± 6.5 28.5 ± 7.9 25.7 ± 6.4
BMI, kg/m 2 22.2 ± 3 21.6 ± 4.1 22.2 ± 2.8 21.1 ± 1.1 22.3 ± 3.1
Facial pattern, B/M/D a 25/70/7 0/12/0* 25/58/7* 1/11/0 24/59/7 15.3/19.8/7.8 35.4/39.8/24.3 26.8/27/24.2
Mouth opening, mm 51.2 ± 5.8 49.2 ± 5.4 51.5 ± 5.8 52.3 ± 3.3 51.1 ± 6
Operated side, right/left 51/51 6/6 45/45 3/9 48/42 15.4/20.4 36/39.3 25.5/27.6
Previous infections, yes/no 77/25 12/0 * 65/25 * 12/0 * 65/25 * 20.3/10.5 * 39.3/32.5 27.3/24
Nolla stage 9.7 ± 1.1 9.9 ± 0.3 9.7 ± 1.2 10 9.7 ± 1.2
Pell and Gregory position, A/B/C 39/58/5 0/11/1 * 39/47/4 * 0/11/1 * 39/47/4 * 12.8/21.3/17.7 27.2/42.3/64.2 * 21.5/28.7/39.8 *
Pell and Gregory position, I/II/III 8/91/3 0/12/0 8/79/3 0/11/1 8/80/2 11/18.7/11.4 19.9/38.3/66.3 * 15.5/27.2/35
Winter position, MA/H/V/DA b 39/14/29/20 7/2/1/2 32/12/28/18 7/3/0/2 32/11/29/18 21/21/10/22 42/53/19/45 * 27/36/16/34 *
Signs mandibular canal, yes/no 18/84 2/10 16/74 1/10 16/74 18.8/17.7 55.6/33.8 * 33.9/24.9 *
Bone removal, yes/no 85/17 12/0 73/17 12/0 73/17 19.9/8.1 * 42.4/13.7 * 29/14 *
Tooth sectioning, crown/root/no 25/38/39 0/10/2 * 25/28/37 * 0/11/1 * 25/27/38 * 12.3/28.6/11.8 * 34.4/57.8/20.4 * 23.7/38/17.5 *
Soft tissue coverage, total/partial/no 30/64/8 6/6/0 24/58/8 9/3/0 * 21/61/8 * 26.2/14.1/16.8 * 51.4/31.9/32.3 * 32.7/24.3/21 *
Bone coverage, total/partial/no 6/56/40 1/10/1 * 5/46/39 * 1/11/0 * 5/45/40 * 18.7/23.1/10.5 * 57.2/43.6/26.4 * 35.7/30.5/19.6 *
Operation time, min 26.5 ± 14.6 41 ± 13.5 * 24.6 ± 13.7 * 40.3 ± 12.9 * 24.7 ± 13.8 *
Difficulty VAS, mm 37.6 ± 21.4 61.7 ± 19.4 * 34.4 ± 19.6 * 64.8 ± 16.3 * 34 ± 19.3 *
Behaviour VAS, mm 17.9 ± 21.2 42.4 ± 20.7 * 14.6 ± 19.1 * 53.3 ± 13.2 * 13.2 ± 17.2 *
MDAS, Modified Dental Anxiety Scale; DFS, Dental Fear Survey; VAS, visual analogue scale; BMI, body mass index.

a B, brachycephalic; M, mesocephalic; D, dolichocephalic.

b MA, mesioangular; H, horizontal; V, vertical; DA, distoangular.

* Statistically significant difference between anxious and non-anxious patients ( χ 2 test, Fisher’s exact test, t -test, or analysis of variance (ANOVA); P < 0.05).

Table 2
Pearson correlations of dental anxiety and surgical difficulty variables.
ISAR MDAS DFS STAI-state STAI-trait Behaviour VAS Difficulty VAS OT
MDAS 0.69 **
DFS 0.78 ** 0.72 **
STAI-state 0.77 ** 0.71 ** 0.74 **
STAI-trait 0.44 ** 0.44 ** 0.51 ** 0.56 **
Behaviour VAS 0.73 ** 0.66 ** 0.71 ** 0.60 ** 0.29 **
Difficulty VAS 0.48 ** 0.43 ** 0.45 ** 0.34 ** 0.38 ** 0.56 **
OT 0.49 ** 0.42 ** 0.40 ** 0.35 ** 0.40 ** 0.60 ** 0.85 **
Age 0.18 0.11 0.13 0.14 0.06 0.23 * 0.42 ** 0.36 **
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Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Patient anxiety and surgical difficulty in impacted lower third molar extractions: a prospective cohort study

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