This randomized clinical trial was designed to compare three different reduction methods for anterior temporomandibular joint (TMJ) dislocation. The three methods evaluated were the conventional method, wrist pivot method, and extraoral method. The study sample comprised 90 consecutive patients suffering from anterior dislocation of the TMJ, who were allocated randomly to one of the three groups. This study found success rates of 86.7% for the conventional method, 96.7% for the wrist pivot method, and 66.7% for the extraoral method. The extraoral method was more difficult for the physician and the patient than the other two methods. For the patients, the wrist pivot method was easier than the other methods. For the doctors, the extraoral method was significantly more difficult than the other methods. In conclusion, due to the absence of a biting risk with the extraoral method and the lack of a significant difference in success between this method and the conventional method, the extraoral method could be considered the appropriate first-line treatment where there is a risk of the patient biting the surgeon’s hand. Given the overall benefits of the wrist pivot method, this method could be considered the first-line and gold standard treatment modality in other cases.
Temporomandibular joint (TMJ) dislocation can occur in any direction, but the most common is acute anterior dislocation. This usually occurs spontaneously and may be caused by yawning, laughing, seizures, or intraoral procedures such as tooth extractions.
Several methods have been proposed for jaw reduction. With the conventional method, which is now used widely, the physician stands in front of the patient and puts his/her thumbs on the patient’s lower molars and other fingers on the mandibular body and angle. The physician then applies continuous force in the lower and posterior direction. However, due to masseter muscle spasm and the patient pulling their head backwards throughout the reduction procedure, this method of reduction may be difficult for the physician. There is also a risk of biting and the transmission of infectious diseases such as hepatitis and HIV with this procedure. Because of these disadvantages, researchers continue to look for alternative methods.
One such alternative is the wrist pivot method, which was introduced in recent years. With this method, the doctor puts his/her thumbs in the submental area of the patient and places the other fingers over the lower molars. The doctor then makes an ulnar deviation and small flexion of the wrist. To date, there is no evidence-based data on the advantages and disadvantages of this method.
Several extraoral methods to eliminate the risk of biting have been proposed to date. Among these, the method of Chen et al. is of note, although its efficacy has been shown to be less than that of the conventional method in some studies. With this method, the doctor puts his/her thumb on the dislocated coronoid process and places the other fingers of that hand behind the mastoid process. On the opposite side, the thumb of the other hand is put on the malar eminence and the other fingers on the mandibular angle area. The coronoid is then pushed back on the dislocated side by the thumb.
The present study was performed to systematically assess these methods of TMJ reduction so that the most appropriate method can be chosen for each patient. A clinical trial design was used for this study.
Materials and methods
Study design and patients
This was a randomized clinical trial study (Iranian Registry of Clinical Trials number IRCT201304249039N2). The study was conducted at a tertiary referral centre for otorhinolaryngology in the city of Tehran. The purpose of the study was to perform a comprehensive assessment of the different TMJ reduction methods in patients with acute anterior dislocation of the mandible. After obtaining informed consent, the patients were allocated to one of three groups by simple randomization. Their jaw reduction was then done by one of the three different methods. Based on a sample size calculation, 30 cases were assigned to each group. The power of the study was assumed to be 80%. Patients were recruited over a 2-year period (2012–2014).
The inclusion criterion was the presence of anterior mandibular dislocation, and the exclusion criteria were posterior dislocation, dislocation associated with fracture, and traumatic dislocation. There was no patient loss during enrolment, allocation, or analysis.
After admission and diagnosis of the pathology, the patient was assigned to group A, B, or C by simple randomization. They were given an opaque envelope by a nurse, in which the group type was written. Patients in group A were approached using the conventional method, those in group B with the extraoral method, and those in group C with the wrist pivot method ( Figs. 1 and 2 ).
In all groups, the reduction was done by two otolaryngology residents who had been trained in all reduction methods and had passed the required learning curve before starting the study. Following the reduction procedure and when the patient’s condition was stable, a questionnaire that had been designed for the study was used to gather the necessary information from the patient and physician; the information was recorded on special forms that were given to the patient and to his/her physician.
If the jaw reduction procedure was proving unsuccessful after 2 min, the method was considered to have failed, and another method was selected for reduction by the physician. To prevent patient crossover among the groups, the information from the second reduction was not included in the analysis.
The patient outcomes were evaluated as follows: (1) the success rate of the reduction was calculated for each group; (2) the degree of difficulty of the reduction for the surgeon was scored from 1 to 10 on a verbal numeric scale (VNS), with 1 being very easy and 10 being very difficult; and (3) the degree of difficulty of the reduction for the patient was scored from 1 to 10 on a VNS, with 1 being very easy and 10 being very difficult.
Various parameters for statistical analysis were recorded using the questionnaire, including patient age, patient sex, unilateral or bilateral dislocation, recurrent or primary dislocation, time delay before seeing the doctor, the need for a muscle relaxant, the duration of the reduction in seconds, the success or failure of the reduction, the degree of difficulty for the surgeon and for the patient (on a VNS), and any history of seizures, dementia, or an infectious viral disease in the patient.
Dentures or any other foreign material must be taken out of the mouth. If a muscle relaxant is needed, patient monitoring, an intravenous line, and oxygenation should be established. The physician must wear gloves and protect their thumbs by wrapping gauze or placing a plastic splint around them.
The physician stands in front of the patient and puts his/her thumbs on the patient’s lower molars. The patient must sit on a chair so that his/her mandibular level is not above the doctor’s elbow; this will allow the physician to apply the most effective force. The physician’s other fingers are placed on the mandibular body and angle. The physician then applies continuous force in the lower and posterior direction. When the masseter muscle is relaxed, the mandible moves downwards and backwards. At the same time, additional force can be applied upwards on the mentum with the third and fourth fingers. This will help mandibular rotation. With this movement, the mandible moves more towards the back and downwards, the condyle slips into the glenoid fossa, and thus the reduction is achieved. For bilateral dislocation, both sides can be reduced at the same time; however, it is easier to first reduce one side and then the other ( Fig. 1 A).
With this method, the doctor puts his/her thumb on the dislocated coronoid process and places the other fingers of that hand behind the mastoid process. On the opposite side, the other thumb is placed on the malar eminence and the other fingers on the mandibular angle area. For the reduction, the fingers against the angle of the mandible apply force towards the front, and the coronoid is pushed back on the other side by the thumb. The fingers behind the mastoid also apply extra force. Thus, the mandible turns and the condyle is reduced ( Fig. 2 ).
Wrist pivot method
The patient sits in front of the doctor. The doctor puts his/her thumbs in the submental area of the patient and places the other fingers over the lower molars. The doctor then makes an ulnar deviation and small flexion of the wrist. Thus, the patient’s mandible rotates and the condyle goes downwards and backwards, entering the glenoid fossa. In this way, both sides should be reduced at the same time. This is unlike the conventional and extraoral methods, in which each side can be reduced individually or together ( Fig. 1 B).
Data obtained using the questionnaires were analyzed using IBM SPSS Statistics version 21.0 software (IBM Corp., Armonk, NY, USA), through analysis of variance (ANOVA), t -test, and Fisher’s exact test. Significance was set at a P -value of less than 0.01.
The total sample comprised 90 patients; 42 (46.7%) were male and 48 (53.3%) were female. The patients ranged in age from 15 to 90 years, with an average age of 47.46 ± 21 years. The average delay before arrival at the hospital was 3 ± 4 h (range 10 min to 29 h). The dislocation was a recurrence for 66 patients (73.3%); there was no previous history of dislocation for the other 24 patients (26.7%). Table 1 shows the comparison of these variables between the study groups. The percentages of recurrent cases and of bilateral dislocations did not differ significantly between the three groups ( P = 0.32 and P = 0.73, respectively).
|Conventional ( n = 30)||Extraoral ( n = 30)||Wrist pivot method ( n = 30)||P -value|
|Age, years, mean (min–max)||47.1 (15–87)||47.9 (18–90)||47.4 (18–85)||0.99|
|Recurrent disease, yes/no||20/10||21/9||25/5||0.32|
|Duration of dislocation before visit, hours, mean (min–max)||3.6 (0.2–29)||2.8 (0.5–21)||2.7 (0.5–15)||0.65|
Using ANOVA and post hoc tests (Bonferroni), it was found that there was a significant difference between the three methods in terms of difficulty for the doctors ( P = 0.00). For the doctors, the extraoral method was significantly more difficult than both the conventional ( P = 0.003) and wrist pivot ( P = 0.000) methods (Bonferroni test). However, there was no significant difference in difficulty between the conventional and wrist pivot methods ( P = 0.36).
There was a significant difference between the three methods in terms of difficulty for the patients ( P = 0.00). According to the patients, the wrist pivot method was easier than the other methods ( P = 0.007 vs. conventional method and P = 0.000 vs. extraoral method). The average difficulty reported by the patients (VNS) for the conventional method was lower than that for the extraoral method (4.8 compared to 5.6), but this difference was not statistically significant ( P = 0.64).
Comparing the duration of the reduction between the three groups, the P -value was 0.01 ( P < 0.01 considered significant). With regard to the duration of the reduction, there was a significant difference only between the extraoral and wrist pivot methods ( P = 0.007); the average duration of the reduction was 28.1 s for the extraoral method and 11.65 s for the wrist pivot method. No significant difference was seen for the other comparisons.
The comparisons of the study parameters are shown in Tables 2–4 .
|Difficulty for physician
VNS 1–10, mean (min–max)
|3.9 ± 3.08 (1–10)||6.4 ± 3.1 (1–10)||0.003|
|Difficulty for patient
VNS 1–10, mean (min–max)
|4.8 ± 2.54 (1–10)||5.6 ± 2.73 (1–10)||0.64|
|Duration of reduction, seconds, mean (min–max)||17.38 ± 16.05 (3–60)||28.1 ± 26.67 (2–110)||0.14|