The objective of this study was to assess the anatomical changes to the condyle and articular disc following mandibular advancement surgery, the adaptation of the masticatory muscles, and the improvement or worsening of temporomandibular disorders (TMD) in patients with pre-existing disorders and those who developed them following surgery. Four databases were searched systematically: PubMed, Scopus, Embase, and Cochrane Library. Of the 544 articles initially selected, 219 were duplicates and a further 165 were excluded on the basis of their titles and abstracts. On reading the full text, 89 were excluded because they were of no interest and 43 because they did not meet the inclusion criteria. Of the remaining 28 articles, six were excluded because they were considered of low quality and 22 articles were reviewed. Mandibular advancement surgery with condyle repositioning is associated with less TMD. Condylar resorption is a physiological process with a multifactorial aetiology. It is accelerated following mandibular advancement surgery but is not a contraindication to this procedure. Despite the large number of studies on the effects of mandibular advancement surgery on the temporomandibular joint (TMJ), this surgery can neither be said to improve nor to worsen TMJ health.
Temporomandibular joint (TMJ) health is of prime importance for stable results in orthognathic surgery. If the TMJ is not in good condition, the outcome of the surgical procedure could be unsatisfactory in terms of function, aesthetics, stability, and pain. Consequently, any type of pain and/or dysfunction in the head, neck, or TMJ must be assessed before performing orthognathic surgery. The most frequent temporomandibular disorders (TMDs) are disc displacements, with or without reduction. They affect young adult women to a greater extent, and often occur in patients with mandibular retrognathia. The bilateral sagittal split osteotomy (BSSO) is the surgical procedure of choice to correct the most complex cases. Mandibular advancement surgery not only improves aesthetics and function, but also brings an improvement in the airways.
Orthognathic surgery to advance the mandible entails adaptive muscular changes, but the results are not always stable. Degenerative changes in the condyle play an important part in relapses, but the biomechanical changes that influence the length of the oral muscles following mandibular advancement are also a significant factor.
Some authors consider that changes in condyle position during surgery can increase the risk of an early relapse and encourage the development of TMDs or worsen existing ones. Opinions differ on whether repositioning the condyle prior to surgery occasions greater or lesser relapses and/or recovery times.
The greater prevalence of TMD following orthodontic and surgical treatment of retrognathic patients continues to be a subject of debate. Some have stated that patients present early discomfort following surgery but adapt within a period of between 6 months and 2 years, and that this adaptation is greater or lesser depending on the advancement attained during surgery. In contrast, others consider that the symptoms worsen, so there is a clear division of opinions, making it difficult to draw reliable conclusions.
The objective of this systematic review was to evaluate muscular and articular adaptive changes following orthognathic mandibular advancement surgery and assess the prevalence of TMD signs and symptoms before and after this surgical procedure. A further aim was to evaluate the anatomical changes in the condyle and the adaptation of the masticatory muscles following surgery.
Materials and methods
A systematic review of the literature was carried out in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations and CONSORT criteria.
Study selection criteria
The selection criteria for the articles to be included in the review encompassed articles, articles in press, and reviews of studies conducted in adults. Only the following types of study were accepted: systematic reviews and meta-analyses, randomized controlled trials (RCTs), and cohort studies and case–control studies, both prospective and retrospective. All those that investigated adaptation and muscular and anatomical changes in the TMJ following mandibular advancement surgery were accepted. Several articles comparing the effects of different surgical advancement techniques on the TMJ were also included.
Search strategy and screening of articles
To identify the relevant studies, irrespective of language, a detailed electronic search was carried out in the PubMed, Scopus, Embase, and Cochrane Library databases. All studies published between 2002 and 2014 were included. The search was updated on 1 December 2014.
The data search included a combination of nine primary terms concerning mandibular advancement surgery: “orthognathic surgery”, “maxillofacial surgery”, “jaw surgery”, “mandibular advancement surgery”, “mandibular advancement”, “mandibular retrognathism”, “BSSO”, “bilateral sagittal split osteotomies”, and “malocclusion, Angle class II”. A further six secondary terms referring to the TMJ and articular and muscular problems were also included: “temporomandibular disorders”, “TMD”, “temporomandibular effect”, “temporomandibular joint”, “TMJ”, and “muscular changes”. All the possible combinations between these words were explored.
Two reviewers independently assessed the titles and abstracts of all the articles. In the event of disagreement, discussions were held until consensus was reached; however, if the reviewers continued to disagree, a third reviewer was consulted. If the abstract did not provide sufficient information for a definite decision on inclusion or exclusion, the full article was obtained and reviewed before the final decision was made.
The variables selected for comparison between the studies were the following: demographic variables (sex and age), sample size, type of study, follow-up time, diagnostic method, and conclusions ( Table 1 ). Lastly, the articles were classified as being of high, medium, or low quality according to the CONSORT criteria, as adapted by Mattos et al.
|Authors, year||Study type||Sample size||Age (years) a and sex (M/F)||Diagnostic method||Follow-up time in months (T0 = preop.)||Conclusions||Study quality b|
|Beukes et al. (2013)||RS||Cases 25
|Cases 23, 9/16
Controls 26.6, 7/18
|Lateral teleradiology of cranium||T0 = 3–4 days preop.
T1 = 0.25 and 6 months postop.
|Patients whose medial pterygoid muscle and stylomandibular ligament were stripped during surgery showed greater long-term stability||M|
|Franco et al. (2013)||PS||27||26.7 ± 13.2, 9/18||CBCT||T1 = 12 and 36 months postop.||The mandibular advancement surgery was stable, however after 1–3 years, 20% presented changes in condyle position||M|
|Kobayashi et al. (2012)||RS||6||21, 1/5||CT, lateral teleradiology of cranium||T0 = 0.25 months preop.
T1 = 0.25 and 12 months postop.
|Condylar resorption following surgery was observed and caused relapse. It is essential for the condyles to be stable before surgery||H|
|Maal et al. (2012)||PS||18||32 (17–55), 6/12||CBCT, 3D photography||T0 = 1 month preop.
T1 = 12 months postop.
|The use of 3D techniques is essential for precise, objective documentation of surgical changes||H|
|Näpänkangas et al. (2013)||RS||15||51.1, 9/6||Clinical examination||T0 = 1 month preop.
T1 = 1, 3, 6 and 24 months postop.
|In the long-term, TMD did not increase following surgery||M|
|Carvalho et al. (2010)||PS||27||30.04 ± 13.08, 9/18||CT, CBCT||T1 = 0.25, 0.5, 12 months postop.||Following advancement, postero-superior displacement of both condyles and resorption occurred. 3D assessment showed great individual variability in bone stability||H|
|Abrahamsson et al. (2009)||RS||Cases 121
|Cases 22.5 ± 7.4, 51/70
Controls 23.4 ± 7.4, 23/33
|Questionnaire, clinical examination, lateral teleradiology||T0 = preop. (not stated)
T1 = postop. (not stated)
|Following surgery, myofascial pain without limited opening increased and DDR and arthralgia were observed, as well as other general signs and symptoms of TMD||M|
|Dervis and Tuncer (2002)||PS||Cases 50
|Cases 29.3, 21/29
Controls 29.8, 22/28
|Clinical examination, TMJ dysfunction indices||T0 = 0.25 months preop.
T1 = 0.25, 12 and 24 months postop.
|Significant reduction in TMD 2 years after surgery. TMJ functional status can be improved with orthognathic surgery||M|
|Di Palma et al. (2009)||RS||19||17–34, 9/10||CT, electromyography||T0 = preop. (not stated)
T1 = 6–8 months
|Improvement in TMD signs and symptoms. Electromyography showed this was due to greater occlusal stability||M|
|Gonçalves et al. (2008)||RS||72||30, 13/59||Lateral teleradiology of cranium, clinical examination, MRI||T0 = preop.
T1 = 0.2 months
T2 = 24 months
|Maxillomandibular advancement is a stable procedure for patients with healthy TMJs and for patients undergoing simultaneous TMJ disc repositioning. Patients with preoperative TMJ articular disc displacement who underwent double-jaw surgery and no TMJ intervention experienced significant relapse||M|
|Dicker et al. (2008)||RS||18||28, 7/11||Lateral teleradiology of cranium, MRI||T0 = 1 month preop.
T1 = 27 months postop.
|The volume of the medial pterygoid muscle increased in the brachyfacial patients who underwent surgery, but decreased in the dolichofacial cases||H|
|Rezende Frey et al. (2008)||PS||127||30, 103/24||Lateral teleradiology of cranium||T0 = 0.5 months preop.
T1 = 0.25, 1.5, 6, 12, 24, and 60 months postop.
|Anti-clockwise rotation is related to an increase in muscular symptoms following BSSO. The distance advanced should not be considered a risk factor for TMD development||M|
|Dicker et al. (2007)||RS||12||31, 5/7||MRI||T0 = 1 month preop.
T1 = 18 months postop.
|Reduction in size of mandibular opening and closing muscles following advancement||H|
|Van den Braber et al. (2006)||RS||12||–||Study of masticatory performance||T1 = 12 and 60 months postop.||Mandibular advancement had a positive effect on oral function||H|
|Van Lierde et al. (2006)||RS||8||26.1, 3/5||Clinical study and occlusal examination||T0 = 0.25 months preop.
T1 = 3 months postop.
|After surgery, the patients showed the same joint pattern (normal or disturbed) as before the operation||M|
|Saka et al. (2004)||RS||Cases 14
|–||MRI||T0 = 1 month preop.
T1 = 9.3 months postop.
|Fixing the condylar process in the articular fossa prior to surgery is a risk prevention factor. Without repositioning, the postoperative period was longer||M|
|Yamada et al. (2004)||RS||Cases 27
|22 ± 5||Questionnaire, CT||T0 = preop. (not stated)
T1 = postop. (not stated)
|After advancement surgery in patients with TMD, flattening of the articular eminence may occur as a result of erosion, favouring the appearance of disc displacement without reduction||M|
|Wolford et al. (2003)||RS||25||49 ± 2, 2/23||CT, lateral teleradiology of cranium||T0 = preop. (not stated)
T1 = 12 months postop.
|The condition of patients suffering from TMD may worsen after this surgery; 24% ( n = 6) developed condylar resorption||H|