Effect of Orthognathic Surgery on Temporomandibular Disorders: A Prospective Study

Abstract

Purpose

The relationship of orthognathic surgery and temporomandibular disorders (TMD) has always been a topic of debate. The results have varied from mild/moderate improvement to actual worsening in some cases. The purpose of this study was to evaluate the effects of orthognathic surgery on TMD in patients with dentofacial deformities.

Method

An observational study was conducted on 56 patients (112 condyles) of patients with dentofacial deformities with age range of 19–35 years who underwent orthognathic surgery. TMD was evaluated using seven types of disorders in diagnostic criteria for TMD (DC/TMD, 2010) pre-operatively and after 6-month follow-up.

Results

There was minimal decrease in unassisted mouth opening without pain, maximum unassisted mouth opening and maximum assisted mouth opening after surgery. There was significant improvement in joint sounds and headache in 18 patients. Overall, there was improvement in 29 cases (33.93%), worsening in 8 cases (14.29%) and no change in 19 cases (33.93%).

Conclusion

There was high prevalence of TMDs in dentofacial deformity patients. Most of the patients with pre-operative TMD improved with orthognathic surgery, whereas a small percentage of patients who were asymptomatic pre-operatively developed TMD after surgery and in some patients TMD worsened. The risk of developing TMD and worsening of severity conditions is low.

Introduction

Temporomandibular disorders (TMD) are major cause for non-dental origin pain in the maxillofacial region. TMDs are thought to be multifactorial in origin with malocclusion being a potential risk factor. Based on a review of relevant literature, it has been estimated that the contribution of occlusal factors to the development of TMD is approximately 10–20% [1] with other factors being trauma to the masticatory apparatus, metabolic conditions and psychosocial factors [2].

The purpose of orthognathic surgery is to correct facial deformity and malocclusion and to obtain normal orofacial function. There are changes in the position of the mandibular condyles. There are reports of various degree of improvement in TMD because of improved occlusal stability and reduced emotional stress, whereas few studies have reported deterioration or no change in TMD after orthognathic surgery [3–11]. Therefore, the definite result regarding the effect of orthognathic surgery on TMD is still controversial. The present study was designed to know the effect of orthognathic surgery on TMD.

Methodology

This observational study was designed as a single centre, prospective and single arm after obtaining ethical clearance from the Institutional Ethical Committee. Fifty-six young adults with dentofacial deformities who were planned for orthognathic surgery in the form of Lefort I osteotomy and bilateral sagittal split osteotomy (BSSO) either alone or in combination from 1st July, 2013 to 30th June, 2018 were included in the study after taking written informed consent. All patients with syndromes, clefts, post-traumatic deformity, history of condylar pathology and distraction osteogenesis were excluded from the study. Preformed acrylic splint was used intraoperatively for guiding of occlusion. Manual repositioning of condyle in the glenoid fossa was done. Semi-rigid fixation with miniplates was performed followed by light maxillomandibular training elastics for about two to three weeks.

Clinical Examination and Assessment

Patients were assessed pre-operatively and six months post-operatively on the basis of clinical parameters like (i) mouth opening; (ii) lateral and (iii) protrusive movements, (iv) joint pain and (v) sounds. They were also evaluated on the basis of DC-TMD [12]. The Research Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) specifies a dual-axis diagnostic system for temporomandibular disorders (TMD) supported by a well-operationalised history and examination protocol. They were divided into seven subtypes:

• Subtype I–Myalgia.

• Subtype II–Disc displacements with or without reduction.

• Subtype III–Arthralgia.

• Subtype IV–Combination of Type I, II.

• Subtype V–Combination of Type I, III.

• Subtype VI–Combination of Type II, III.

• Subtype VII–Combination of I, II, III.

Statistical Analysis

The data collected were entered into Microsoft excel worksheet and analysed using Statistical Package for Social Sciences, version 18.0 (SPSS Inc., Chicago, IL, USA). Descriptive statistics including mean, standard deviation and proportions were computed. The normality of data was analysed by the Shapiro–Wilk test, and appropriate parametric tests were used to check differences in mean. Paired t test was used to compare mean scores before and after treatment. Chi-square statistics or Fischer’s exact test was employed to check association of categorical variables. A p value of < 0.05 was considered as significant for all statistical inferences.

Results

A total of 56 patients with age range 19–35 years were included in the study with equal number of males and females, i.e. 28 males and 28 females. Sixteen patients underwent Lefort I maxillary advancement, 16 patients underwent BSSO mandibular advancement, and 24 patients underwent Bijaw surgery of Maxillary advancement at Lefort 1 level and BSSO mandibular setback.

Clinical Parameters (Tables 1, 2)

Mouth Opening, Lateral Excursions and Protrusion (in mm)

There was minimal decrease in unassisted mouth opening without pain, maximum unassisted mouth opening, and maximum assisted mouth opening after surgery. Lateral excursions and protrusion were also decreased minimally. Changes in protrusion, maximum unassisted and assisted mouth opening are statistically significant.

Joint Sounds

There was improvement in the joint sounds in the post-operative period. Twenty-eight patients (50%) had clicking pre-operatively, whereas this number decreased to 10 (17.85%). Five patients developed clicking after surgery, whereas 5 patients had no improvement in the clicking sound.

Joint Pain

Twenty-seven (48.21%) patients had joint pain pre-operatively. The number reduced significantly to 6 (10.71%) patients post-operatively.

Myalgia

There was significant reduction in muscle pain. Nineteen (33.96%) patients had muscle pain pre-operatively, whereas it was in 7 (12.52%) patients post-operatively.

Headache

Twenty-one (37.5%) patients had headache pre-operatively that decreased significantly to 3 (5.35%) patients post-operatively.

Changes in joint pain and sounds, myalgia and headache are statistically significant.

Subtypes Assessment (Table 3)

Table 3.

Comparison of pre-operative and post-operative TMD subtypes

Type of TMD	Pre-operative TMD	Post-operative TMD	P value
None	20 35.71%	34 60.7%	0.12
Type I	1 1.7%	5 8.92%	–
Type II	4 7.14%	4 7.14%	–
Type III	3 5.35%	5 8.92%	0.5
Type IV	1 1.78%	1 1.78%	–
Type V	7 12.5%	1 1.78%	–
Type VI	3 5.35%	2 3.57%	–
Type VII	17 30.35%	4 7.14%	0.008

Table 1.

Comparison between pre-operative and post-operative clinical parameters assessed

Clinical parameters assessed (n 56)	Pre-operative	Post-operative	P value
Myalgia present	19 (33.92%)	7 (12.56%)	0.03
Joint sounds	28 (50%)	10 (17.85%)	0.01
Joint pain	27 (48.21%)	6 (10.71%)	0.001
Headache	21 (37.5%)	3 (5.35%)	< 0.001

Table 2.

Comparison between pre-operative and post-operative mouth opening, lateral excursions and protrusions (in mm)

Mouth opening	Pre-operative M.O. ± S.D	Post-operative M.O. ± S.D	P value
Unassisted mouth opening without pain	40.98 ± 6.79	39.66 ± 5.96	0.067
Maximum unassisted mouth opening	46.18 ± 6.60	43.91 ± 6.28	0.004
Maximum assisted mouth opening	50.38 ± 6.79	47.85 ± 6.40	0.002
Right lateral excursion	6.59 ± 1.88	6.24 ± 1.48	0.06
Left lateral excursion	6.52 ± 1.75	6.32 ± 1.72	0.17
Protrusion	5.99 ± 1.77	5.24 ± 1.41	< 0.001

Thirty-six out of 56 patients had TMD sign and symptoms pre-operatively, whereas this number decreased to 22 post-operatively. Overall, there was improvement in 29 cases (33.93%), worsening in 8 cases (14.29%) and no change in 19 cases (33.93%).

• Myalgia (Subtype I) was noted in 1 patient pre-operatively that increased to 5 patients post-operatively.

• Number of patients with disc displacement (Subtype II) remained 4 out of 56 patients both pre- and post-operatively.

• Arthralgia (Subtype III) was noted in 3 patients pre-operatively and increased to 5 patients post-operatively.

• Subtype IV (Combination of Type I, II) was seen in only 1 patient pre-operatively and post-operatively.

• Subtype V (Combination of Type I, III) decreased from 7 patients pre-operatively to only 1 patient post-operatively.

• Subtype VI (Combination of Type II, III) decreased marginally from 3 patients pre-operatively to 2 patients post-operatively.

• Subtype VII (Combination of I, II, III) decreased significantly from 17 patients pre-operatively to 4 patients post-operatively.

Change in subtype VII was statistically significant.

Discussion

Orthognathic surgery affects both hard and soft tissue in the maxillofacial region. The condyle position is also affected due to orthognathic surgery under the influence of various factors like patient position during operation, fixation method, surgical technique and bony interference between proximal and distal segment under the influence of general anaesthesia. If there is any change of the position of the condyle, it can result in the change of the position of the articular disc that may lead to post-operative TMD. But some studies have asserted that remodelling defined as bony apposition of posterosuperior areas of the condyle and the temporomandibular fossa can occur [13]. Condylar displacement and changes of muscle tone may influence remodelling phenomena. Mavreas and Athanasiou [14] reported that there was post-operative condylar displacement which was reduced to normal position 6 months later, and it resulted from remodelling of the condyle and articular fossa. These factors may have some role in improvement or causation of TMD.

TMD was evaluated on the basis of DC-TMD [12] instead of Helkimo anamnestic index, [4, 15, 16] which consist of three parts, i.e. anamnestic dysfunction index, clinical dysfunction index and occlusal index. The demerits of Helkimo are: it is unreliable in nature [17] and different types of TMD cannot be diagnosed with its parameters [18]. DC/TMD includes a specific diagnostic criterion which covers every aspect of TMD, its psychological component and its related disability. DC assesses the extent to which a person with TMD may be impaired cognitively, emotionally and behaviourally and how these factors may contribute to the development or maintenance of disorder. Besides, both of the DC/TMD components are supported as reliable, valid and clinically useful.

Kutilla et al. [19] reported that 5–35% of adults had subjective symptoms of TMD, while clinical signs are estimated to be twice as common as symptoms. According to Ghai et al. [20], the prevalence of TMD is thought to be greater than 5% of the population. In our study, prevalence of TMD was 64.29% in patients with dentofacial deformity which is higher than normal population. The possible explanations for high prevalence are: 1) psychosocial factors like stress, depression and the presence of multiple somatic symptoms in dentofacial deformity patients. 2) Functional impairments between TMJ, muscles and occlusion are more in dentofacial deformity patients. 3) Behavioural factors such as tooth clenching or grinding are commonly found in dentofacial deformity patients.

In the present study, patients had more signs and symptoms of TMD before surgery. Dujoncquoy et al. [7] reported high (80.0%) incidence of TMJ dysfunction in their study and so did Schinder et al. [21] (80%), Link et al. [22] (97%) and Panula et al. [23] (73.3%) in their respective studies. These results corroborated with the present study. Other studies reported that patients presenting for surgical correction of dentofacial deformity had lower prevalence: Karabouta and Martis [24] reported 40.8%, White and Dolwick reported 49.3% of pre-operative TMJ dysfunction [3], and Upton et al. [16] (53.0%), Onizawa et al. [10] (66.7%), Devris et al. [3] (60%), Krestens et al. [25] (16.2%) and De Clercq and Abeloos [26] had 26.5% symptoms of dysfunction pre-operatively in their sample. This wide disparity might be explained by differences in age, race and evaluation methods used.

There was significant improvement in Subtype VII TMD (Combination of subtype I. II and III). Our results were in agreement to the result of Dujoncquoy et al. [7], Abrahamson et al. [8] and Togashi et al. The possible explanations for improvement of TMD after surgery are:

1. There is increase in neuromuscular coordination and decrease in functional impairment between TMJ, muscle and occlusion.

2. Decrease in abnormal loading and stress of TMJ complex due to reduced parafunctional activities.

3. Decrease in degenerative changes in TMJ due to decrease in synovial and articular disc inflammation.

4. Increase in condyle–disc relationship.

5. Improvement in psychological status of the patients due to improvement in their mastication, expression and appearance.

6. There is good intercuspation of teeth after surgery.

The possible reasons for worsening of TMD after surgery may be due to discrepancy in centric relation and centric occlusion. Mostly, the surgeons rely on manual repositioning the condyle in condylar fossa after osteotomy and before fixation. The ideal post-operative position should be the position where the remodelling volume of the TMJ induced by post-operative biomechanical stress would be the smallest and degenerative change is not induced; however, it is still difficult to predict post-operative stress on the TMJ, including disc tissues. If condyles are not placed properly then there are chances of developing signs and symptoms of TMD, but after few days when adaptation occurs to new position, the signs and symptoms may decrease with time. By using condylar repositioning devices, this might be avoided; in the present study, condylar repositioning devices were not used. Currently, there is no evidence that condylar repositioning devices help in reduction of TMD. Other reasons could be muscular degeneration or fibrosis or unstable occlusion.

Orthognathic surgery can lead to condylar resorption, and there may be increase in the signs and symptoms of TMD. Surgical risk factors that contribute to post-operative condylar resorption are controversial. In the present study, we did not use imaging techniques to see condylar resorption. But clinically, we did not see any signs or symptoms of condylar resorption in our patients.

Therefore, it further vindicated the findings of the present study that orthognathic correction of dentofacial deformity leads to improvement of TMD signs and symptoms. However, after surgical correction of the dentofacial deformity, changes in TMD signs and symptoms do not always show improvement. In some patients TMD symptoms and signs may change for the worse, or in symptom-free patients TMD symptoms may develop after orthognathic surgery. Our results coincided with meta-analysis of Al–Moraissi et al. [27].

Conclusion

There is high prevalence of TMDs disorders in dysgnathic/dentofacial deformity patients. Most of the patients with pre-operative TMD improved with orthognathic surgery, whereas a small percentage of patients who were asymptomatic pre-operatively developed TMD after surgery and in some patients TMD worsened. There is need of long-term studies with large sample along with the radiographic evaluation of the condyle to comment upon the condylar change.

Funding

No funding has been received for this study.

Declarations

Conflict of interest

The authors have no conflict of interest to declare.