Mulder MJHL; Spierings ELH

Research Article

J Dent & Oral Disord. 2017; 3(5): 1075.

Treatments of Orofacial Muscle Pain: A Review of Current Literature

Mulder MJHL¹* and Spierings ELH²

¹Department of Neurology, Erasmus Medical Center, Rotterdam, Netherlands

²Division of Craniofacial Pain, Department of Diagnostic Sciences, Tufts University School of Dental Medicine; Headache & Face Pain Program, Department of Neurology, Tufts Medical Center and Tufts University School of Medicine, USA

*Corresponding author: Maxim J.H.L. Mulder, Department of Neurology, Erasmus University Medical Center, Rotterdam, Netherlands

Received: September 12, 2017; Accepted: October 16, 2017; Published: October 23, 2017

Abstract

Background: There are a large number of treatment options for Orofacial Muscle Pain (OMP). It remains uncertain which treatments are the most effective when it comes to reducing spontaneous pain resulting from OMP.

Objective: The purpose of the present paper is to review the controlled medical/dental studies related to the treatment of OMP.

Methods: For an inventory of the treatments, we researched the literature without time limit and with PubMed® as the search engine, using the term OMP as well as the numerous synonyms encountered while reviewing the papers generated. We focused on effects of treatment on spontaneous pain. We divided the treatment studies into negative-controlled and non-controlled studies and analyzed them separately.

Results: The literature search generated 58 studies on 18 different treatment options, each including 9 to 90 patients. Of 13 treatments the effect on spontaneous pain was studied compared to a negative-controlled group. The treatments that showed benefit in randomized, blinded, negative-controlled studies were: myofascial therapy, laser, botulinum toxin, ping on ointment, melatonin, and gabapentin.

Conclusions: A number of studies lacked a negative control and were underpowered as to the number of subjects included. The reviewed studies suggest efficacy for6 different treatments: myofascial therapy, laser, botulinum toxin, ping on ointment, melatonin, and gabapentin.

Keywords: Face pain; Orofacial muscle pain; Temporomandibular disorder; Masseter myalgia; Spontaneous pain

Introduction

Chronic orofacial pain is relatively common and affects an estimated 7% of the general Western population [1]. It is commonly caused by Orofacial Muscle Pain (OMP), with pain located peripherally in the face or in the jaw(s), non-neuropathic in nature, and generally continuously present [2]. The pain of OMP originates from the muscles of mastication, particularly the masseter muscles. The cause is a dysfunction of those muscles, resulting in myalgia [3]. In the most recent classification for temporomandibular disorders, myalgia is a subcategory within muscle pain of the masticatory muscles and it assembles: local myalgia, myofascial pain and myofascial pain with referral. It should be distinguished from tendonitis, spasm and myositis [4].

In the literature, OMP is described under a great variety of terms as listed (Table 1). There is a wide range of treatment options available for OMP with the primary purpose of reducing spontaneous pain in these patients. Despite the fact that orofacial pain caused by OMP is a commonly encountered problem, it remains uncertain which treatments are most effective. This results in large practice variety, suboptimal treatment, and prolonged disability. Therefore, we aimed to review the current literature on the treatments of OMP.

Methods

Using the terms listed in Table 1, we conducted extensive research of the literature on the medical/dental treatments of OMP. We used PubMed® as the search engine and applied no time limit. We performed the search in November 2016. Only studies in English that reported spontaneous pain scores in humans as an outcome measure were included and studies that reported surrogate endpoints only, such as pressure pain threshold or un-assisted mouth opening, were not included. The treatment should have been performed in patients with OMP only and not in mixed patient populations (i.e., patients with other temporomandibular disorders). Case reports, i.e., series of less than five patients, were excluded. The studies were analyzed in two sections: negative-controlled studies (placebo-, sham-, and waiting list-controlled) and non-controlled studies. Comparative studies without a negative control were analyzed under the section of non-controlled studies, separately for the treatments compared.

Table 1: Myofascial Temporomandibular Disorder (TMD): synonymous terminology.




  
    Facial pain with masticatory hyperactivity
  
  
    Masseter muscle pain
  
  
    Masseter myalgia
  
  
    Masticatory muscle pain
  
  
    Masticatory muscle spasm
  
  
    Masticatory myofascial pain
  
  
    Myalgia of the masseter muscles
  
  
    Myalgia of the masticatory system
  
  
    Myofascial pain of the jaw muscles
  
  
    Myofascial pain of the masticatory muscles
  
  
    Myofascial pain syndrome of the masticatory muscles
  
  
    Myofascial temporomandibular pain 
  
  
    Myogenic temporomandibular disorder
  
  
    Myogenouscraniomandibular disorder
  
  
    Myogenous facial pain
  
  
    Myogenous orofacial pain
  
  
    Myogenous pain of the masticatory muscles
  
  
    Myogenous temporomandibular disorder
  
  
    Orofacial muscle pain
  
  
    Orofacial pain of muscular origin
  
  
    Pain in the masticatory muscles
  
  
    Tendomyopathy of the masticatory musculature
  
  
    Temporomandibular disorder with myofascial pain
  
  
    Temporomandibular disorder of myogenous origin
  
  
    Temporomandibular disorder with pain in the masticatory    muscles
  
  
    Temporomandibular myofascial pain



Table 1: Myofascial Temporomandibular Disorder (TMD): synonymous
terminology.

Results

Fifty eight studies met our selection criteria, each including 9 to 90 patients. Of 18 different treatments, the effect on spontaneous pain resulting from OMP was investigated (Table 2).Twenty eight studies used a negative control group, concerning 13 different treatments (73%; Table 3). Eight treatments (44%) were studied in both negative and non-negative controlled studies and 5 treatments (27%) were only studied with-out negative control (Table 4).

Table 2: Treatments of myofascial Temporomandibular Disorder (TMD) evaluated in (negative-) controlled and non-controlled studies.




  
    Treatment
    Controlled studies
    Non-controlled studies
  
  
    Self-care
    0
    3
  
  
    Myofascial therapy
    1
    4
  
  
    Chiropractic therapy
    0
    1
  
  
    Electrical stimulation
    0
    1
  
  
    Laser
    6
    3
  
  
    Dry needling
    1
    1
  
  
    Acupuncture
    3
    1
  
  
    Stabilization appliance
    4
    8
  
  
    Partial-coverage appliance
    1
    1
  
  
    TheraBite®
    0
    1
  
  
    NTI^a(-like) appliance
    0
    1
  
  
    Botulinum toxin
    4
    3
  
  
    Melatonin
    1
    0
  
  
    Gabapentin
    1
    0
  
  
    Ping on ointment
    1
    0
  
  
    Muscle relaxants
    1
    0
  
  
    Analgesics
    2
    0
  
  
    Muscle relaxants and analgesics
    2
    2
  
  
    ^aNociceptive    trigeminal inhibition



Table 2: Treatments of myofascial Temporomandibular Disorder (TMD) evaluated
in (negative-) controlled and non-controlled studies.

Table 3: Placebo-, sham-, and waiting-list-controlled studies in myofascial temporomandibular disorder.




  
    Author(s)
    Blinding
    Randomized
    Design
    Number of subjects^a
    Treatment
    Positive outcome^b
  
  
    Kalamiret al. (2012) [5] 
    Rater
    Yes
    Parallel
    61^c
    Myofascial therapy
    Yes^d
  
  
    Shiraniet al. (2009) [6] 
    Double
    Yes
    Parallel
    16
    Laser
    Yes
  
  
    Godoy� et al. (2015)    [8] 
    Single
    Yes
    Parallel
    9
    Laser
    No
  
  
    Maia� et al. (2012) [9] 
    No
    No
    unclear
    21
    Laser
    No
  
  
    Ahari et al. (2014) [11] 
    Double
    Yes
    Parallel
    20
    Laser
    No
  
  
    Conti� et al. (1997)    [10] 
    Double
    Yes
    Parallel
    10
    Laser
    No
  
  
    Salmos-Brito (2012) [7] 
    Double
    Yes
    Parallel
    58
    Laser
    Yes
  
  
    Goddard et al. (2002) [27] 
    Double
    Yes
    Parallel
    18
    Dry needling
    No
  
  
    Shen & Goddard (2007) [25] 
    Single
    Yes
    Parallel
    15
    Acupuncture
    No
  
  
    Shen et al. (2009) [24] 
    Single
    Yes
    Parallel
    28
    Acupuncture
    No
  
  
    Katsouliset al. (2010) [26] 
    No
    No
    Parallel
    11
    Acupuncture
    No
  
  
    Dao et al. (1994) [23] 
    Double
    Yes
    Parallel
    61
    Stabilization appliance
    No
  
  
    Ekberg et al. (2003) [22] 
    Double
    Yes
    Parallel
    60
    Stabilization appliance
    No
  
  
    Daif (2012) [19] 
    No
    Yes
    Parallel
    40
    Stabilization appliance
    Yes
  
  
    Qvintuset al. (2015) [21] 
    No
    Yes
    Parallel
    80
    Stabilization appliance
    No
  
  
    Al Quran & Kamal (2006) [20] 
    No
    No
    Parallel
    76
    Stabilization appliance
    Yes
  
  
    Al Quran & Kamal (2006) [20] 
    No
    No
    Parallel
    76
    Partial-coverage appliance
    Yes
  
  
    Kurtogluet al. (2008) [14] 
    Double
    Yes
    Parallel
    20
    Botulinum toxin
    No
  
  
    Von Lindernet al. (2003) [12] 
    Single
    Yes
    Parallel
    90
    Botulinum toxin
    Yes
  
  
    Nixdorf et al. (2002) [13] 
    Double
    Yes
    Cross-over
    10^c
    Botulinum toxin
    No^d
  
  
    Ernberget al. (2011) [15] 
    Double
    Yes
    Cross-over
    20^c
    Botulinum toxin
    No^d
  
  
    Li et al. (2009) [16] 
    Double
    Yes; 1 study
    Parallel
    45^c
    Ping On ointment
    Yes^d
  
  
    Vidor et al. (2013) [17] 
    Double
    Yes 1 study
    Parallel
    32
    Melatonin
    Yes
  
  
    Kimoset al. (2007) [18] 
    Double
    Yes 1 study
    Parallel
    44
    Gabapentin
    Yes
  
  
    Varoliet al. (2015) [29] 
    Double
    Yes
    Cross-over
    18
    Diclofenac
    No
  
  
    Panacea^e
    No
  
  
    Singer &� Dionne    (1997) [28] 
    Double
    Yes
    Parallel
    39^c
    Diazepam
    No^d
  
  
    Ibuprofen
    No
  
  
    Combination
    No
  
  
    a Total number of subjects in treatment group with controls.    When multiple treatment options were given patients of the specific treatment    in the table and control are provided.
      ^bStatistically    significant group difference (p<0.05).
      cCompleters.
      ^dCompleter analysis.
      ^ediclofenac+ carisoprodol+ acetaminophen+ caffeine



Table 3: Placebo-, sham-, and waiting-list-controlled studies in myofascial temporomandibular disorder.

Table 4: Non-controlled treatment studies in myofascial temporomandibular disorder.




  
    Author(s)
    Number    of subjects
    Treatment
    Positive
  
  
    outcome ^a
  
  
    Michelottiet    al. (2004) [36] 
    23^b
    Self-care
    No^c
  
  
    Michelottiet    al. (2012) [35] 
    23
    Self-care
    Yes
  
  
    Gavishet    al. (2006) [32] 
    10
    Self-care
    No
  
  
    Michelottiet    al. (2004) [36] 
    26^b
    Myofascial    therapy + self-care
    No^c
  
  
    Guarda-Nardiniet    al. (2012) [41] 
    15
    Myofascial    therapy
    No
  
  
    Gavishet    al. (2006) [32] 
    10
    Myofascial    therapy
    Yes
  
  
    Kraaijengaet    al. (2014) [34] 
    41
    Myofascial    therapy
    Yes^c
  
  
    DeVochtet    al. (2013) [31] 
    20
    Chiropractic    therapy
    No
  
  
    Almeida    et al. (2009) [30] 
    12
    Electrical    stimulation
    Yes
  
  
    Tullberget    al. (2003) [42] 
    12
    Laser
    No
  
  
    �zet    al. (2010) [43] 
    40^b
    Laser
    Yes^c
  
  
    Melchior    et al. (2014) [44] 
    12
    Laser
    No
  
  
    Gonzalez-Perez    et al. (2015) [45] 
    23^b
    Dry    needling
    Yes^c
  
  
    Grilloet    al. (2015) [46] 
    20
    Acupuncture
    Yes
  
  
    Naikmasuret    al. (2008) [47] 
    20
    Stabilization    appliance
    Yes
  
  
    Nilneret    al. (2008) [48] 
    33
    Stabilization    appliance
    Yes
  
  
    �zet    al. (2010) [43] 
    20^b
    Stabilization    appliance
    Yes^c
  
  
    Jokstadet    al. (2005) [33] 
    20
    Stabilization    appliance
    Yes
  
  
    Michelottiet    al. (2012) [35] 
    18^b
    Stabilization    appliance
    No^c
  
  
    Grilloet    al. (2015) [46] 
    20
    Stabilization    appliance
    Yes
  
  
    Vilanovaet    al. (2014) [49] 
    50^b
    Stabilization    appliance
    Yes
  
  
    DeVochtet    al. (2013) [31] 
    20
    Stabilization    appliance
    No
  
  
    Nilneret    al. (2008) [48] 
    32
    Partial-coverage    appliance
    Yes
  
  
    Jokstadet    al. (2012) [33] 
    18^b
    NTI(-like)    appliance^d
    Yes^c
  
  
    Kraaijengaet    al. (2014) [34] 
    38
    TheraBite�
    Yes^c
  
  
    Guarda-Nardiniet    al. (2012) [41] 
    15
    Botulinum    toxin
    No
  
  
    Pihutet    al. (2016) [50]
    42
    Botulinum    toxin
    Yes
  
  
    Sidebottom et al. (2013) [51]
    62
    Botulinum    toxin
    Yes
  
  
    Naikmasuret    al. (2008) [47] 
    20
    Muscle    relaxants and analgesics
    Yes
  
  
    Gonzalez-Perez    et al. (2015) [45] 
    16^b
    Muscle    relaxants and analgesics
    No^c



Table 4: Non-controlled treatment studies in myofascial temporomandibular disorder.

The treatments that showed benefit in randomized, blinded, negative-controlled studies were: myofascial therapy, laser, botulinum toxin, ping on ointment, melatonin, and gabapentin (Table 3). Myofascial therapy showed effect on spontaneous pain in one rater-blinded, randomized study (61 patients) [5]. Laser was effective in two double-blinded, randomized studies (16-58 patients). [6,7]. Four other studies, of which 3 were single or double blinded and 3 were randomized, showed no effect of laser (9-21 patients) [8- 11]. Botulinum toxin was effective in one single-blinded, randomized study (90 patients) [12]. In the other three double-blinded, randomized studies, no effect was shown (10-20 patients) [13-15]. Ping on ointment, melatonin, and gabapentin were all effective in single, double-blinded, randomized studies [16-18]. Treatment with stabilization appliance was effective in two non-blinded studies, of which one was randomized (40 and 76 patients, respectively) [19,20]. Three other studies, of which two were double-blinded and randomized, showed no effect [21-23]. Partial coverage appliance was effective in one non-blinded, non-randomized study [20]. Acupuncture was not effective in three studies [24-26]. Dry needling showed no effect in one study [27]. NSAIDs, muscle relaxants, alone or in combination, were not effective either [28,29]. Self-care, chiropractic therapy, electrical stimulation, NTI (-like) appliance, and TheraBite® were only studied in small non-negative-controlled studies (10-38 patients).

Discussion

In this review, we gathered all published studies that investigated treatments of OMP and their effect on spontaneous pain. Fifty eight studies met our selection criteria, investigating the effect of 18 different treatments. The studies that were blinded randomized and compared treatment effect to negative controls showed effect for: myofascial therapy, laser, botulinum toxin, ping on ointment, melatonin, and gabapentin.

We considered negative-controlled studies that were blinded and randomized as best available evidence. Six treatments showed to be effective in spontaneous pain reduction in this study design: myofascial therapy, laser, botulinum toxin, ping on ointment, melatonin, and gabapentin. Myofascial therapy, ping on ointment, melatonin, and gabapentin showed effect in one study each [5,16- 18]. For these modalities, there were no other studies to confirm this effect. Laser was effective in 2 out of 6 negative-controlled studies. Of the two positive studies, one was clearly larger than the rest (58 versus = 21 patients) [6-11]. Botulinum toxin was effective in one out of 4, which was also clearly the largest study (90 versus = 20 patients) [12-15].

Stabilization appliance was only effective in two non-blinded studies [19,20] and not in three other studies of which two were double-blinded and randomized [21-23]. Partial coverage appliance was only effective in one non-blinded, non-randomized study [20]. Therefore and based on the available evidence, we consider the stabilization and partial coverage appliances ineffective. Negative controlled studies showed that the following treatments were not effective in reducing spontaneous pain: dry needling, acupuncture, NSAIDs, muscle relaxants, and NSAIDS combined with muscle relaxants. For the treatments that were only studied in small, nonnegative controlled studies (self-care, chiropractic therapy, electrical stimulation, NTI(-like) appliance, and TheraBite®) the effect on spontaneous pain remains unsure [30-36].

Considering the muscular mechanism of the pain in OMP, it is not surprising that myofascial therapy, laser, and botulinum toxin are potentially beneficial. Ping on ointment has been used as soothing massage balmas the oils they contain are considered to be antiinflammatory and have peripheral analgesic effects [16]. The effect of melatonin is suggested to result from improved sleep, which is usually disturbed in OMP [17]. The possible effect of gabapentin, which is generally considered a medication effective in neuropathic pain. The authors suggested myofascial TMD to be a problem of central pain perception rather than of local (muscle) tissue injury [18]. They base their assumption on a study, where it was shown that patients with masticatory muscle pain have increased sensitivity to pressure stimulation of masseter- and temporalis-muscle sites only and not of peripheral non-painful finger sites, compared to controls [37]. Also in fibromyalgia, gabapentin may possibly provide therapeutic benefit [38,39].

Overall, the quality of the studies was not very high, with many studies lacking a negative control. Fur-thermore, all studies included limited numbers of patients (9-90), resulting in them being underpowered. Also, only a few of the studies that showed treatment effects were replicated. Therefore, no hard conclusions can be drawn on what the best treatment is for reducing spontaneous pain from OMP.

Given the limitations of this review, the best available evidence for treatments to be used in clinical practice based on our findings are: myofascial therapy, laser, botulinum toxin, and ping on ointment, melatonin, and gabapentin. We suggest that the ultimate choice of treatment is made with this evidence in mind, on a personalized basis. When a patient presents with OMP and there is sleep problems involved, a combination of myofascial therapy, laser or ping on ointment with melatonin is reasonable to consider. If these treatment modalities fail, botulinum toxin or gabapentin may be considered as next step, despite their side effects. Botulinum toxin may be considered better in OMP treatment when spasm occurs concurrently or when there is evidence of very tight muscles. Gabapentin may be considered when the muscles are not that tense at all, and the cause of orofacial pain is considered to be primarily a pain perception problem. Furthermore patient preference for one of these treatments should be considered carefully. In randomized, controlled trials for diseases were multiple treatment options are available, patients with a treatment preference are usually excluded, which often leads to underestimation of the treatment benefit [40]. When the patient treatment preference is taken into account (shared decision making), the probability of treatment success will improve regardless of the choice of treatment.

More research in the form of randomized, double-blinded, negative-controlled studies is imperative, with special attention paid to the number of subjects included and, hence, the power of the studies, especially to confirm (myofascial therapy, laser, botulinum toxin, ping on ointment, melatonin, and gabapentin) or test (dry needling, acupuncture, and the treatments studied without negative control) the effects of the studies reviewed.

Conclusion

While OMP as a cause of face pain and its clinical presentation seems well established, its medical/dental treatment in the various modalities has not been well researched. Based on the current literature, 6 out of 18 studied treatment modalities may be beneficial in reducing spontaneous pain in these patients.

References

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Citation:Mulder MJHL and Spierings ELH. Treatments of Orofacial Muscle Pain: A Review of Current Literature. J Dent & Oral Disord. 2017; 3(5): 1075. ISSN:2572-7710

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*Treatment*	*Controlled studies*	*Non-controlled studies*
Self-care	0	3
Myofascial therapy	1	4
Chiropractic therapy	0	1
Electrical stimulation	0	1
Laser	6	3
Dry needling	1	1
Acupuncture	3	1
Stabilization appliance	4	8
Partial-coverage appliance	1	1
TheraBite®	0	1
NTI^a(-like) appliance	0	1
Botulinum toxin	4	3
Melatonin	1	0
Gabapentin	1	0
Ping on ointment	1	0
Muscle relaxants	1	0
Analgesics	2	0
Muscle relaxants and analgesics	2	2
^aNociceptive trigeminal inhibition