Yoko Hasegawa a b, Naoya Kakimoto c 1, Seiki Tomita c, Masanori Fujiwara a, Reichi Ishikura d, Hiromitsu Kishimoto a, Kosuke Honda a
Abstract
Purpose
This study aimed to evaluate the relationship between displacement of the mandibular condyle/disc due to occlusal splint insertion with splint therapy and changes in discomfort of the temporomandibular joint (TMJ), and to clarify the relationships between the outcomes over time of temporomandibular discomfort and TMJ magnetic resonance imaging (MRI) findings at the initiation of splint therapy.
Materials and methods
A total of 75 patients admitted to hospital with discomfort around the TMJ were evaluated. A visual analogue scale for TMJ discomfort was administered during visits for approximately 3 months following the initiation of splint therapy. At the start of splint therapy, magnetic resonance imaging (MRI) was performed with and without splint insertion, and condyle and disc movements were evaluated. Disc balance, disc position and function, disc configuration, joint effusion, osteoarthritis, and bone marrow were evaluated. Linear regression and multiple regression analyses were used to clarify relationships between changes in discomfort and the factors evaluated.
Results
There was no significant correlation between TMJ discomfort and condyle/disc movement with splint insertion. TMJ discomfort was significantly relieved by splint therapy regardless of temporomandibular MRI findings. Unilateral anterior disc displacement and marked or extensive joint effusion fluid were significantly improved with splint therapy.
Conclusion
Discomfort tended to remit with splint therapy regardless of temporomandibular MRI findings. Improvement of TMJ discomfort appears more likely to occur in patients with unilateral anterior disc displacement and with an apparent organic disorder, such as a joint effusion.
Introduction
An occlusal splint (splint) is known to be an effective treatment for many temporomandibular disorders (TMDs) (Dao and Lavigne, 1998, Dao et al., 1994, Wenneberg et al., 1988). Splint therapy is a reversible nonsurgical option for management of TMD (Dylina, 2001) and can reduce pathologic symptoms around the temporomandibular joint (TMJ) caused by excessive occlusal pressure on the TMJ by external forces. In this manner, the splint restores blood circulation to the TMJ by maintaining a wide gap between the mandibular condyle (condyle) and the mandibular fossa (Ettlin et al., 2008, Moncayo, 1994). We previously evaluated deviation of the condyle position and articular disc (disc) on magnetic resonance imaging (MRI) performed at initiation of splint therapy, and we found that the condyle deviates anteroinferiorly and rotates counterclockwise with splint insertion. Additionally, such a pattern of joint movement in wearing the splint has been associated with relief of joint pain (Hasegawa et al., 2011). This study showed that splint therapy might be an effective treatment for TMJ disc derangement manifesting as joint pain.
However, it cannot be confirmed that splint therapy reduces symptoms of joint discomfort other than pain, such as a catching sensation with condyle movement or functional limitation due to TMJ disc derangement. TMJ discomfort, which is subjective, is associated with joint pain, joint sounds with functional movements, restricted range of motion, and/or changes in the movement pattern of the mandible, hypertonus of jaw muscles, and so on (Manfredini et al., 2011). Factors that cause discomfort are intertwined in a complex manner, and clinicians may be puzzled over the appropriate therapy for patients with TMJ discomfort. The possibility exists that the development of joint pain accompanied with some TMJ discomfort cannot be prevented by splint therapy, because patients who continue to experience TMJ symptoms are most likely suffering from an associated dysfunction in autonomic activity (Maixner et al., 2011). Namely, manifestations of TMJ discomfort vary, depending on many subjective symptoms (Dao et al., 1994). However, the fact is that splint therapies are overwhelmingly selected for various forms of TMJ discomfort, as well as TMJ pain. We previously reported that splint-related anterior movement of the condyle was associated with TMJ pain, and that splint therapy was not likely to be successful for any kind of TMJ abnormalities (bone marrow abnormalities and biconvex disc) (Hasegawa et al., 2017). On the other hand, the target symptoms did not involve joint discomfort in that study.
The present study was carried out to evaluate the role of splint therapy in the treatment of TMJ symptoms accompanied by discomfort. To put it more concretely, the objectives of the present study were to clarify: 1) the relationship between displacement of the condyle/disc due to occlusal splint insertion and changes in TMJ discomfort with splint therapy; and 2) the relationship between the long-term prognosis of discomfort around the TMJ and MRI findings at the start of splint therapy.
Section snippets
Subjects
Patients with a history of clicking, catching, or restricted mouth opening and unilateral or bilateral joint pain, and complaints of some subjective symptoms around the TMJ who had been referred to Osaka University Dental Hospital and Hyogo College of Medicine Hospital from February 2009 to January 2013 and who provided informed consent were enrolled. The subjects of this study are the same as those of our previous report (Hasegawa et al., 2017). The present study was performed with the
Patient outcomes
The mean RCdiscomfort of all patients was −53.6 (confidence interval: −63.6 to −43.6; P < 0.001).
Table 1 shows the values for condyle/disc movement and age, and the correlation coefficients between these variables and RCdiscomfort. There was no significant correlation between RCdiscomfort and condyle/disc movement with splint insertion.
Table 2 shows the results of a generalized linear model analysis related to RCdiscomfort. Unilateral ADD and marked or extensive joint effusion were
Discussion
Many patients with TMDs are treated with stabilization splints, which provide relief of masticatory myalgia and pathologic symptoms of TMJ (Dao et al., 1994, Ekberg et al., 1998). We previously reported a cross-sectional study that examined the relationship between the displacement of the temporomandibular condyle/disc by splint insertion and temporomandibular joint pain (Hasegawa et al., 2011). Although such discomfort is expressed ambiguously and involves many factors (such as pain, noise,
Conclusions
The conclusions of the present study are as follows: 1) movement of the condyle and disc with splint insertion had no relationship to the relief of TMJ discomfort; 2) discomfort tended to remit with splint therapy regardless of any temporomandibular MRI findings; and 3) improvement of TMJ discomfort would be easy in patients with unilateral ADD and with an apparent organic disorder, such as a joint effusion.
Funding
This study was supported by a grant from the Ministry of Education, Science and Culture of Japan (grant numbers 25463043 and 15K20464).
Conflicts of interest
None.
Acknowledgements
The authors would like to express their sincere appreciation to K. Yoshikiyo, M. Shiramizu, and K. Yasukawa for their tremendous support.
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