Despite the extensive use of oral splints in the treatment of temporomandibular disorders (TMD) and bruxism, their mechanisms of action remain controversial Various hypotheses have been proposed to explain their apparent efficacy (i.e., true therapeutic value), including the repositioning of condyle and/or the articular disc, reduction in the electromyographic activity of the masticatory muscles, modification of the patient's "harmful" oral behavior, and changes in the patient's occlusion. Following a comprehensive review of the literature, it is concluded that any of these theories is either poor or inconsistent, while the issue of true efficacy for oral splints remains unsettled. However, the results of a controlled clinical trial lend support to the effectiveness (i.e., the patient's appreciation of the positive changes which are perceived to have occurred during the trial) of the stabilizing splint in the control of myofascial pain. In light of the data supporting their effectiveness but not their efficacy, oral splints should be used as an adjunct for pain management rather than a definitive treatment. For sleep bruxism, it is prudent to limit their use as a habit management aid and to prevent/limit dental damage potentially induced by the disorder. Future research should study the natural history and etiologies of TMD and bruxism, so that specific treatments for these disorders can be developed.

Oral Splints: the Crutches for Temporomandibular Disorders and Bruxism?:

Various types of oral appliances (OAs) have been used for over half a century to treat temporomandibular disorders (TMDs), but there has been considerable debate about how OAs should be designed, how they should be used, and what they actually do therapeutically. However, there is enough information in the scientific literature at this time to reach some evidence-based conclusions about these issues. The main focus of this review is on the materials and designs of various OAs in terms of their proposed mechanisms of action and their claimed clinical objectives. Based on current scientific evidence, an analysis is presented regarding the role that OAs can or cannot play in the management of TMDs. Finally, the concept that OAs may be an effective treatment modality for some TMDs owing to their potential for acting as an elaborate placebo rather than any specific therapeutic mechanism is considered.

Oral appliances in the management of temporomandibular disorders

An investigative study of the effects of hard and soft occlusal splints on nighttime bruxism is presented. Occlusal splints are commonly used for the treatment of nocturnal bruxism. This study investigated the effects of hard and soft occlusal splints on nighttime muscle activity. The nocturnal muscle activity of ten participants was recorded while wearing a hard and then a soft occlusal splint. The hard occlusal splint significantly reduced muscle activity in eight of the ten participants. The soft occlusal splint significantly reduced muscle activity in only one participant while causing a statistically significant increase in muscle activity in five of the ten participants.

The effects of hard and soft occlusal splints on nocturnal bruxism

The relationship between the dental occlusion and temporomandibular disorders (TMDs) has been one of the most controversial topics in the dental community. In a large epidemiological cross-sectional survey - the Study of Health in Pomerania (Germany) - associations between 15 occlusion-related variables and TMD signs or symptoms were found. In other investigations, additional occlusal variables were identified. However, statistical associations do not prove causality. By using Hill's nine criteria of causation, it becomes apparent that the evidence of a causal relationship is weak. Only bruxism, loss of posterior support and unilateral posterior crossbite show some consistency across studies. On the other hand, several reported occlusal features appear to be the consequence of TMDs, not their cause. Above all, however, biological plausibility for an occlusal aetiology is often difficult to establish, because TMDs are much more common among women than men. Symptom improvement after insertion of an oral splint or after occlusal adjustment does not prove an occlusal aetiology either, because the amelioration may be due to the change of the appliance-induced intermaxillary relationship. In addition, symptoms often abate even in the absence of therapy. Although patients with a TMD history might have a specific risk for developing TMD signs, it appears more rewarding to focus on non-occlusal features that are known to have a potential for the predisposition, initiation or perpetuation of TMDs.

The dental occlusion as a suspected cause for TMDs: epidemiological and etiological considerations

Introduction: Bruxism is an oral parafunction prevalent in all age groups which is characterized by the involuntary teeth grinding and/or clenching that may occur at any time of the day. It has a multifactorial etiology associated with occlusal and psychological factors and / or habits that can compromise the orthognatic system that may bring negative consequences. Objective: To make a revision article from the existing literature on the etiological factors, clinical manifestations and treatment of bruxism. Materials and methods: Data search was accomplished using Pubmed and ScienceDirect databases applying the keywords “bruxism”, “etiology and symptoms”, “attrition injuries”, “teeth grinding”, “muscular-articular disorders”, “TMJ dysfunction”. From the 102 articles, after analysis of all the abstracts, 34 articles and 4 textbooks were included. Results: The main consequences of bruxism are muscle fatigue, pain, use of incisal edges and occlusal surfaces of the teeth, and in more severe cases teeth loss, headache, periodontal lesions and temporomandibular joint disorders (TMJ disorders). These clinical manifestations may increase the difficulty of oral rehabilitation of edentulous areas and teeth restoration. They may also cause vertical dimension loss and the decrease of patients’ quality of life. Early diagnosis and identification of the etiologic factors are important to prevent the progression of lesions in the orofacial structures such as pain relief of the craniofacial muscles, restoration of the lost structures and reestablishment of vertical dimension. Conclusion: Bruxism presents a high frequency in all age groups and has become an important oral health issue. This parafunctional habit consists in an important change in the oral sensory-motor system, requiring a multidisciplinary approach, in order to reduce injuries in osteodental structures. Lately, its prevalence has increased and is associated with several factors such as stress, drugs, anxiety and sleep disorders, among others. The dentist should be aware of the signs and symptoms in order to prescribe the best treatment, providing the patients a better quality of life.

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D.C. Berry

Papers

Occlusal changes following use of soft occlusal splints.