Sistema miofuncional orofacial e trauma de face : revisão crítica da literatura Changes in the orofacial myofunctional system after treatment for facial trauma : a critical review of the literature

Introduction: This qualitative literature review aims to highlight international scientific publications selected from the PubMed database that describe the changes in the function of the orofacial myofunctional system after facial trauma and the associated treatment outcomes. Methods: Studies published in English between 2005 and 2011 . r . ir. l t. 1 ; (1):1 1-8 DOI: 10.5935/2177-1235.2014RBCP0025


INTRODUCTION
Facial trauma involves injuries to the facial soft tissues and bones, and, in cases of extensive trauma, the brain, eyes, sinuses, and teeth.The epidemiology of this form of trauma is diverse and varies with type, severity, and cause of the injury 1 .
The primary cause of maxillofacial fractures is road accidents 2,3 .However, increased interpersonal violence 1 and the use of firearm bullets also lead to an increased incidence of facial trauma.
The effects of facial trauma may be reversible or irreversible and may lead to emotional, functional, and esthetic impairments.The incidence of facial fractures is higher in men than in women.However, over the past few decades, the incidence has increased in women aged below 40 years [5][6][7] , with a lower incidence in children and individuals older than 40 years 8,9 .
Changes in the organs of articulation after facial trauma are a topic of great interest in the field of speech and language therapy.Such changes interfere with stomatognathic functions such as breathing, speaking, chewing, and swallowing.Speech therapy based the changes in the function of the orofacial myofunctional system after facial trauma is an important complementary treatment because it helps in restoring normal oral functions and decreases the risk of hypomobility and prevents the progression of possible sequelae [10][11][12][13][14][15] .
In the abovementioned context, this literature review was performed to analyze scientific publications describing changes in the function of the orofacial myofunctional system after facial trauma, specifically in the maxilla and mandible, and the associated treatment outcomes.

METHODS
This qualitative literature review included articles selected from the PubMed database using the following keywords: "facial injuries and oral muscle," "facial injuries and oral structure," "facial injuries and speech," "facial injuries and voice," "facial injuries and chewing," "facial injuries and mastication," "facial injuries and deglutition," "facial injuries and swallowing," "facial injuries and breathing," "facial injuries and myofunctional system," and "facial injuries and oral function."All studies published in English between 2005 and 2011 and including all age groups were included.
To establish the principles of the research method employed, the precepts of the Cochrane Handbook 16 were followed with regard to formulation of the question, location, study selection, and critical evaluation.
For appropriate study selection, it was first necessary to achieve compatibility among the researchers.The articles were independently searched in the database by the authors, with the aim to minimize possible citation loss.Studies published in languages other than English were excluded.Studies without full text access (obtained from the CAPES Journal Portal); those appearing multiple times because of overlapping keywords; full articles submitted as case studies, literature reviews, or letters to the editor; and studies that were not directly related to the subject (studies related to surgical technique, fractures in regions of the face other than the maxilla and/or mandible, or changes in sensitivity and animal studies) were also excluded.All phases of the study were independently conducted by the researchers.In case of disagreement, stud-ies were included on the basis of a final consensus.This study was not a simple blind search.
The study selection flowchart is illustrated in Figure 1.

Figure 1. Study selection flowchart
After the bibliographic survey and study selection, the manuscripts were analyzed with regard to the aims, number, and gender of the participants, age groups, evaluated parameters, treatment controls, and results.This analysis is described in subsequent session.

RESULTS
The results of the literature search used in this study are briefly described in Table 1.

DISCUSSION
The findings of this literature review indicated that most of the studies aimed at the evaluation of mandibular function 17,18,21,24,25,27,[28][29][30] and the analysis of treatment outcomes 19,22,23,26  The bite force of the patients significantly decreased in the first week after surgery compared with that in the control group and became equivalent to that in the control group after 6 weeks.

Murakami et al., 2009 18
To analyze the mandibular movement and the occlusal condition of patients who underwent conservative treatment for unilateral condylar fractures Fourteen men and four women were divided in two groups: 1) Twelve underwent maxillomandibular fixation + physical therapy

2) Six underwent physical therapy alone
Average age, 38 years

Control group
The participants were evaluated 3 and 6 months after treatment initiation.

Evaluated parameters: mandibular movement
After 6 months, the maximum mouth opening was normal in the patient groups, although the range was lower than that in the control group Recovery of lateralization and protrusion movements was observed.Mandibular deviation was observed on mouth opening, although the values were lower than those before treatment.
After 6 months of treatment, a decrease in the bite force and level of asymmetry in the occlusal contact area was observed.Totally, 56% patients exhibited some form of symptoms and 72% showed signs of objective TMJ dysfunction.
It was found that conservative treatment may be indicated for patients below 15 years old.

Evaluated by a blinded surgeon
There was no significant difference between groups in any of the evaluated parameters assessed at the different time points. 24 investigate the functional outcome of patients who undergo conservative treatment of condylar fractures

Anamnesis
Clinical examination: functionality was scored using the Helkimo index.

Radiological examination
The clinical dysfunction index revealed serious symptoms in 11% patients, moderate symptoms in 39%, mild symptoms in 39%, and the absence of symptoms in 11%.In addition, there were severe alterations in occlusion in 21% patients, moderate alterations in 61%, and the absence of alterations in 11%.Anamnesis revealed the absence of symptoms in 89% patients.According to the established criteria, the conservative treatment of condylar fractures was satisfactory only in 46% patients.The total duration of chewing cycles and the phases of mouth opening and jaw closing were significantly lesser in the control group than in the treated patients, regardless of the chewing side, type of treatment, and evaluation time It was found that unilateral condylar fractures can alter the chewing cycle in adults for several years, particularly on the opposite side of the fracture.Evaluated parameters: free mouth opening evaluated by three-dimensions analysis and division of movement into rotational and translational components and SEMS findings for the masseter, anterior temporal, and sternocleidomastoid muscles during maximum dental intercuspation Moment: between the 6 th and 36 th month of treatment (average of 18 months) Patients presented with a significantly lower range of mouth opening compared with controls, with a greater decrease in the vertical displacement component.
During maximum dental intercuspation, patients showed higher asymmetry and significant higher torque and contraction values for the sternocleidomastoid muscle.
Total recovery of opening movements could be achieved, although the rotational and translational components of this movement were altered.Evaluation: mandibular movements during mastication and computational analysis of the same Evaluation time: 6 weeks, 6 months, and 1 and 2 years after fracture

Evaluated parameters: chewing cycle duration and maximum mandibular excursion during the chewing cycle, with three-dimensional analysis of the latter movement
There was no significant difference between groups in the duration of the chewing cycle and the maximum mandibular excursion.Surgical correction of unilateral condylar fractures was found to have little effect on mandibular movements the chewing pattern.Minor occlusal adjustments were necessary in six patients.
No significant difference was found in the maximum bite force and maximum pain threshold between the fractured side and the normal side in patients with unilateral fractures and between the operated side and nonoperated side in patients with bilateral fractures.
Open reduction and rigid internal fixation of condylar fractures using the intraoral approach requires expertise and was found to be associated with a high risk of postoperative complications.
For better discussion and characterization of the findings and conclusions related to orofacial myofunctional characteristics found in the articles that were fundamental for this study, specific aspects of greater relevance were addressed separately and were divided for didactic purposes into aspects related to the bite force and occlusal contact area, aspects related to static and dynamic occlusion and jaw mobility, and aspects related to pain.
With regard to the bite force and occlusal contact area, three studies showed that the bite force 17,18,26 improved after treatment and over time, two showed an improved occlusal con-tact area 18,26 , and three 18,21,27 reported the presence of asymmetry in these parameters after fracture correction.
With regard to dynamic occlusion, the maximum mouth opening returned to normal in some studies 18,24,27,30 .However, some of these studies 18,27,30 reported a lower range of mouth opening in patients than in controls.In one study 20 , the maximum mouth opening was not restored to normal.
With regard to jaw mobility, one study 18 observed a limited recovery in jaw mobility.In four studies [20][21][22]30 , alterations in jaw mobility persisted in the long term.
The persistence of pain despite treatment was reported in several studies 20,22,29 , and only one study 19 reported a decrease in pain.
In several studies 22,25,27,28,30 , jaw function improved when facial fractures were treated in combination with orofacial myofunctional therapy, and even after surgical and/or conservative treatment, changes in asymmetry and jaw mobility were still observed.The combination of a myofunctional approach with surgery and/or conservative treatment for jaw fractures can improve the overall jaw function.

CONCLUSIONS
Although the number of studies on facial trauma is increasing, few studies address the use and benefits of orofacial myofunctional therapy in this field.Although an increasing number of studies in international databases are emphasizing on the use of orofacial myofunctional therapy in combination with surgery and/or conservative treatment for facial trauma, these are inadequate and provide little scientific evidence.More specific studies are required to demonstrate the benefits of this therapy and define the methodologies that should be applied by skilled professionals.The average lateralization to the side of fracture was 8.4 mm, while that to the contralateral side was 7.8 mm Conservative treatment of condylar fractures in growing individuals was found to result in satisfactory functional outcomes and condylar remodeling.Functional treatment after intermaxillary fixation for 12 to 17 days proved to be acceptable.

1 )
compare the results of open and closed treatments for intracapsular fractures Forty-three patients were divided into two groups: 1) Fourteen (15 fractures) with an average age of 31 years were treated by open reduction with internal fixation 2) Twenty-nine (34 fractures) with an average age of 28 years were treated by closed reduction Clinical examination Radiological examination Axiography Patients treated by internal fixation showed better radiological outcomes Both groups showed signs of persistent dysfunction, although lesser impairment was observed in the group treated with internal fixation Axiography revealed significant limitations in condylar movements in both groups, although TMJ irregularities were significantly less frequent in the open treatment group.It was found that in cases of complex reconstruction of the mandibular condyle, open reduction and internal fixation improve the prognosis of bone anatomy and recovery of soft tissues when combined with therapeutic exercises after surgery.Kaplan et al, 2001 23 To compare the results of open reduction and internal fixation between patients with displaced mandibular fractures who underwent immediate mobilization and those who did not.Twenty-nine patients older than 16 years who underwent open reduction and internal fixation were divided into two groups: Sixteen underwent immediate mobilization 2) Thirteen underwent maxillomandibular fixation for 2 weeks Evaluation time points: six weeks and 3 and 6 months after surgery.Evaluated parameters: pain, fracture healing, occlusal condition, trismus, inferior alveolar nerve condition, weight loss, and wound infection Twenty-eight patients (25 men and three women) with condylar fractures Average age: 30 years .Average time of fracture: 3 years.
longterm outcomes of open reduction and internal fixation for condylar fractures using the intraoral approach Nine men and six women Average age: 42 years A total of 24 condylar fractures Evaluation time points: before and after surgery (average of 23 months) Evaluation: clinical examination, radiological examination, assessment of the psychological status, measurement of maximum bite force in maximal occlusion, pain thresholds in TMJ and chewing muscles measured using a pressure algometer Two patients were diagnosed with impaired TMJ movements Fracture healing was considered satisfactory in 12 joints Mini-plate fracture occurred in three patients and severe bone resorption of the condyle in one.
fixation for 12 to 17 days, liquid diet for 15 days after fixation, and functional treatment (mouth opening exercises) Follow-up: three to 6 years, with an average of 4.7 years Evaluation: palpation and auscultation of TMJs, evaluation of the interincisal distance, and measurement of the maximum lateral excursion of the jaw The maximum interincisal distance during mouth opening varied from 34 to 43 mm (slight deviation to the side of fracture in four patients)