An evidence-based assessment of occlusal adjustment as a treatment for temporomandibular disorders

Sleep bruxism: The past, the present, and the future-evolution of a concept

BACKGROUND

The concept of sleep bruxism (SB) has evolved exponentially over the past several decades. Many theories and hypotheses have been proposed as to the definition, pathophysiology, and management of SB, from the early 1960s through the present. The role of peripheral factors, such as dental occlusion, in the pathogenesis of SB has been discarded.

TYPES OF STUDIES REVIEWED

The authors searched several electronic databases (ie, PubMed, Google Scholar, Web of Science, Embase, and Ovid MEDLINE) for studies on bruxism. The search was conducted from January 1961 through May 2023 and yielded 4,612 articles, of which 312 were selected for comprehensive review after eliminating duplicates and nonfocused articles.

RESULTS

There has been an evident progressive shift from the role of peripheral factors, such as dental occlusion, to more central factors, such as the involvement of a central pattern generator as well as the autonomic nervous system, in the genesis of bruxing movements. There is continued robust interest in the dental community to elucidate the contributing factors involved in SB.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The neurophysiology of SB appears to be leaning more toward central rather than peripheral factors. There is increasing evidence of the role of the autonomic nervous system, genetics, and comorbidities in the genesis of SB. The scientific literature seems to refute the role of dental occlusion in the causation of bruxing movements. As per the literature, there has been a paradigm shift in the definition and genesis of SB and its possible dental implications and management, which also highlights the need for succinct scientific studies in this regard.

Pharmacological therapy in the management of temporomandibular disorders and orofacial pain: a systematic review and meta-analysis

BACKGROUND

Temporomandibular disorders (TMD) are manifested by soreness in the jaw joint area and jaw muscles, clicks or creaks when opening or closing the mouth. All these symptoms can be disabling and occur during chewing and when the patient yawns or speaks. Several classes of drugs are used to treat symptoms. This review aims to assess which drug suits the different signs.

METHODS

Pubmed, Web of Science and Lilacs were systematically searched until 01/02/2023. Clinical trials were selected that dealt with drugs used in temporomandibular dysfunction RESULTS: Out of 830 papers, eight studies were included. The Meta-Analysis with Continuous Outcomes with Pre-Calculated Effect Sizes resulted in the rejection that there is intergroup variability (p.0.74).

CONCLUSIONS

Treatment of orofacial pain is still a significant challenge for dentistry. We can conclude that there is no drug of first choice in the treatment of temporomandibular pain. However, the clinician must distinguish the type of pain and the aetioloic cause of the pain so that the patient can be treated and managed pharmacologically.

Does increasing vertical dimension of occlusion in centric relation affect muscular activity? An electromyographic study

OBJECTIVE

In many esthetic treatments, clinicians may consider the option to modify the maxillo mandibular position. A raise of the vertical dimension of occlusion (VDO) may help restore esthetics, increase the space for dental materials, and reduce the invasiveness of dental procedures. Traditionally, VDO increases are done by using the centric relation (CR) position. Despite a long history of use, the neuromuscular effects of different maxillo mandibular relations are not fully studied. The aim of this study was to investigate the effect of alterations of maxillo-mandibular relation from maximal intercuspal position (MIP) to a raised VDO CR position on jaw-elevator muscle activity.

MATERIALS AND METHODS

Fifteen healthy individuals were asked to carry out maximal voluntary clenching (MVC) in MIP and in CR on individual splints. Electromyographic (EMG) activity of the masseter and anterior temporalis muscles was assessed in μV as the root mean square of the amplitude. Specific indexes and ratios were also computed. Data analyzed in MIP and CR were compared by paired student's t-tests.

RESULTS

MVC levels were not negatively affected by a VDO increase in CR position. On the contrary masseter muscles showed a statistically significant increase (p < 0.005). No significant effect on the anterior temporalis was observed.

CONCLUSION

These results suggest that no immediate negative effect on maximum voluntary clenching was induced by a VDO increase in CR position. A slight increase observed in EMG clenching levels could be explained by the increase in VDO when clenching on the splint.

CLINICAL IMPLICATIONS

The results of this study support the use of CR position as a pragmatic reference position due to the absence of relevant or negative changes in neuromuscular function.

Temporomandibular Disorders: Implications in Restorative Dentistry and Orthodontics

Over the past several decades, the science of restorative/reconstructive dentistry and orthodontics has evolved tremendously, following sound principles passed down from robust literature and scientific rationale. These principles have been solid and instrumental in enhancing dentistry, from a single tooth restoration to complex full-mouth rehabilitations. However, it must be noted that some of the principles and philosophies followed over these decades have been questioned based on the advances in science, technology, and evidence-based medicine. The scenario became complex when clinicians were faced with the question of guidance for optimum joint and muscle health as related to restorative dentistry and orthodontics.

Aspects of Dental Occlusion Assessed with the T-Scan System among a Group of Romanian Dental Students in a Cross-Sectional Study

This study evaluated the occlusal relationships in students with bruxism, using the T-Scan III system, and their correlation with the activity of the masticatory muscles assessed through surface electromyography (sEMG). The study group was divided into two subgroups (based on self-reporting): 20 participants with possible bruxism and 20 participants without possible bruxism; all participants underwent the following evaluations: sEMG recordings using the dia-BRUXO device for masticatory muscles assessment, as well as static and dynamic occlusion using the T-SCAN III system. The analysis of the maximum intercuspidal (MI) position revealed a positive moderate association between the values of the occlusal forces in MI distributed along the two hemiarches, and the number of grinding events during daytime, which was statistically significant (p < 0.05). The analysis of protrusion movements reflected statistically significant differences between the non-working interferences and sEMG parameters specific to bruxism (p < 0.05). The analysis of laterotrusion movements indicated that participants with anterolateral guidance presented higher values of awake bruxism indexes and higher values of clenching events during nighttime. For all three mandibular movements, their duration was higher for the study group compared to the control group. Therefore, this study confirmed the utility of sEMG recordings in the bruxism diagnosis process, as well as the association between dental occlusion and bruxism.

[Bruxism: Classification, Diagnostics and Treatment]

Bruxism: Classification, Diagnostics and Treatment Abstract. Bruxism, the grinding or clenching of teeth, is common in the population. Stress, anxiety syndromes and genetic disposition seem to be dominant factors that lead to increased muscle tension. A distinction is made between two circadian manifestations, sleep and wake bruxism. Bruxism is a major risk factor for tooth structure and dentures. The diagnosis is based on a targeted medical history and examination. Sleep bruxism can be demonstrated by electromyography and video recording in the sleep laboratory. The treatment aims to protect the hard tooth substance and preserve the denture using occlusal splints. Relaxation exercises can improve bruxism. Specialized physiotherapy can improve tension, pain and restricted movement. Botulinum toxin treatment reduces the subjective complaints during the period of action.

Occlusion and Temporomandibular Disorders: A Long-Standing Controversy in Dentistry

The relationship between temporomandibular disorders (TMDs) and occlusion remains controversial. Some authors believe that occlusion is the primary factor in the onset of TMD symptoms, whereas others feel that occlusion has no role in this at all. The majority of reasoning behind causation is based upon anecdotal rather than scientific evidence. Existing evidence in the literature supports the absence of a disease-specific association. This article describes this controversy and provides the reader with findings from contemporary literature.

The Bruxoff Device as a Screening Method for Sleep Bruxism in Dental Practice

Sleep bruxism (SB) is a masticatory muscle activity during sleep and a common phenomenon. Severe SB can have a serious impact on the success of dental treatment. Reliable methods of screening and diagnosing patients with SB are crucial. Therefore, in this study, a Bruxoff device as a potential screening and diagnostic method for sleep bruxism was evaluated. A total of 60 adults participated in this study: 35 patients with symptoms of bruxism (study group) and 25 asymptomatic patients (control group). Data were recorded using Bruxoff. All symptomatic patients participating in the study turned out to be bruxers, while not all asymptomatic patients turned out to be non-bruxers according to the Bruxoff device. Bruxoff is a simple screening device that can be safely used to evaluate masseter muscle activity during sleep. Since the device does not have a built-in microphone and/or video camera and, therefore, cannot record grinding sounds, the objective capabilities of Bruxoff as a single diagnostic device for sleep bruxism are limited.

A Device Improves Signs and Symptoms of TMD

Background

Temporomandibular joint dysfunction (TMD) therapy remains an open challenge for modern dentistry. Herein, we propose a new neuromuscular lingual device able to reduce signs and symptoms of TMD in female patients with chronic orofacial pain.

Methods

50 females with myofascial TMD according to RDC/TMD were randomly assigned to study (n = 25) and control groups (n = 25). At T0, both groups received sEMG/KNG and pain evaluation by the VAS scale. The study group received the ELIBA device (lingual elevator by Balercia) constructed under ULF-TENS (ultra-low-frequency transcoutaneous electrical nervous stimulation). Subjects were instructed to use ELIBA at least for 16 h/day. After 6 months (T1), both groups underwent to sEMG/KNG and VAS revaluation.

Results

T1 study group compared to controls showed a significant reduction in total (p < 0.0001) and mean (p < 0.0001) sEMG values, as well as a significant increase in both maximum vertical mouth opening (p=0.003) and maximum velocity in mouth opening (p=0.003) and closing (p < 0.0001). Interestingly, a significant reduction in pain measured by VAS (p < 0.0001) was reported.

Conclusions

After 6 months, the ELIBA device is able to significantly reduce TMD-associated myogenous pain and to promote the enhancement of sEMG/KNG values.

Practical Implications

ELIBA can be considered as a new device, potentially useful for head-neck pain relief in patients suffering from chronic TMD. In addition, its use promotes a muscles relaxation inducing freeway space increase. This characteristic makes it particularly useful for rehabilitation of patients with not enough space for construction of conventional orthotics or neuromuscular bites.

Temporomandibular Disorders and Headache

Temporomandibular disorders (TMD) and primary headaches can be perpetual and debilitating musculoskeletal and neurological disorders. The presence of both can affect up to one-sixth of the population at any one time. Initially, TMDs were thought to be predominantly musculoskeletal disorders, and migraine was thought to be solely a cerebrovascular disorder. The further understanding of their pathophysiology has helped to clarify their clinical presentation. This article focuses on the role of the trigeminal system in associating TMD and migraine. By discussing recent descriptions of prevalence, diagnosis, and treatment of headache and TMD, we will further elucidate this relationship.

Evaluation of muscle activity, bite force and salivary cortisol in children with bruxism before and after low level laser applied to acupoints: study protocol for a randomised controlled trial

BACKGROUND

Bruxism is a repetitive activity that causes tooth wear, audible sounds, and discomfort. Preventive measures have been studied for conditions that can exert a negative influence on physiological development in children. Low-level laser therapy administered over acupoints is an effective, painless, low-cost treatment option that has achieved good results. Thus, the aim of the proposed study is to evaluate changes in muscle activity, bite force and salivary cortisol in children with bruxism after the application of low-level laser to accupoints.

METHODS

The children will be randomly allocated to four groups of 19 individuals: G1 - low-level laser; G2 - occlusal splint; G3 - placebo laser; and G4 - control (without bruxism). The BTS TMJOINT electromyography will be used to determine muscle activity and a digital gnathodynamometer will be used to measure bite force. Salivary cortisol will be analysed at baseline as well as one and six months after treatment. Two-way ANOVA will be employed and complemented by Tukey's test.

DISCUSSION

Bruxism is a repetitive activity of the masticatory muscles that can have negative consequences if not treated, such as tooth wear, noises, discomfort and anxiety. Thus, control and treatment measures should be taken. Although low-level laser therapy over acupoints has been indicated for children, the effects of this treatment modality have not yet been studied.

TRIAL REGISTRATION

NCT02757261 on 8 April 2016. This study protocol received a grant from the Brazilian fostering agency São Paulo Research Foundation (FAPESP: #2015/24731-0).

A survey on the potential relationships between TMD, possible sleep bruxism, unilateral chewing, and occlusal factors in Turkish university students

OBJECTIVE

To evaluate whether there is a relationship between possible sleep bruxism (PSB), temporomandibular disorders (TMD), unilateral chewing (UC), and occlusal factors in university students recruited from Cumhuriyet University in Turkey.

METHODS

For this cross-sectional survey, 519 (223 males, mean age 21.57 ± 2.3 years, 296 females, mean age 21.02 ± 2 years) university students who admitted to the Department of Oral and Maxillofacial Radiology of the Faculty of Dentistry, Cumhuriyet University for dental care between 2012 and 2014 were selected randomly. Students were asked to complete a questionnaire form including questions about TMD, PSB and UC. Presence and direction of malocclusion were recorded during clinical examination. Chi-square test was used for statistical analysis.

RESULTS

It was found that 96.6% of the students with PSB had TMD (p < 0.05). The prevalence of severe TMD was high among students with PSB. There was a significant association between UC, PSB and TMD (p < 0.05). No statistically significant association was found between occlusal factors and PSB and TMD (p > 0.05).

CONCLUSION

Sleep bruxism, which heavily depends on self-report, is significantly associated with TMD. Unilateral chewing seems to be a common factor for development of SB and TMD. However, further studies are needed to corroborate this finding. Additionally, this study supports the hypothesis that occlusal factors are not related to self-reported sleep bruxism.

Features of occlusal state in female Japanese patients with migraine: a case-controlled study

OBJECTIVES

The prevalence rate of migraines is 8.4%; it is mostly diagnosed in women at 20s to 40s, and is known to cause major physical and mental disruption to daily life. This study was conducted on women aged between their 20s and 40s, in order to investigate the possible differences in the features of the occlusal state between a migraine and a non-migraine (control) group.

METHODS

Age-matched female patients with migraine (n = 60) diagnosed by headache specialists and healthy controls (n = 57) were enrolled. Dental casts were used to evaluate some features.

RESULTS

The maxillary and mandibular dentition casts from the migraine group showed significantly characteristic findings in their Angle's classification, overjet, and deviation in the anterior tooth midline, compared to the control group.

DISCUSSION

The results relating occlusal state to both tension-related headaches and migraines, which have different pathogeneses, suggest the possibility of dental intervention to improve the symptoms of primary headaches.

Differences between centric relation and maximum intercuspation as possible cause for development of temporomandibular disorder analyzed with T-scan III

Objective:

To compare subjects from the group with fixed dentures, the group who present temporomandibular disorders (TMDs) and a control group considering centric relation (CR) and maximum intercuspation (MIC)/habitual occlusion (Hab. Occl.) and to analyze the related variables also compared and analyzed with electronic system T-scan III.

Materials and Methods:

A total of 54 subjects were divided into three groups; 17 subjects with fixed dentures, 14 with TMD and 23 controls-selection based on anamnesis-responded to a Fonseca questionnaire and clinical measurements analyzed with electronic system T-scan III. Occlusal force, presented by percentage (automatically by the T-scan electronic system) was analyzed in CR and in MIC.

Results:

Data were presented as mean ± standard deviation and differences in P < 0.05 were considered significant. After measurements of the differences between CR and MIC in the three groups were noticed varieties but the P > 0.05 it was not significant in all three groups.

Conclusion:

In our study, it was concluded that there are not statistically significant differences between CR and MIC in the group of individuals without any symptom or sign of TMD although there are noticed in the group with TMD and fixed dentures disharmonic relation between the arches with overload of the occlusal force on the one side.

Mandibular function after Myorelaxation Therapy in temporomandibular disorders

PURPOSE

The aim of this study was to analyze the efficacy of Myorelaxation Therapy in temporomandibular disorders on the basis of mandibular movement measurements, reported functional impairment and clinical findings.

MATERIAL/METHODS

To ascertain the mandibular movements 78 women were investigated. The first group consisted of 32 consecutive patients (23.3±4.8 years) suffering from muscle disorder and disk displacement with a reduction serving as a treated group. The second group was formed from 46 volunteers, as a healthy group (20.1±1.3 years). Jaw-tracking records (K7, Myotronics-Noromed Inc.) were performed including the measurements of opening, lateral and protrusive movement range, maximal and average velocity of opening/closing. Reported impairment and clinical data were collected. The treatment involved nocturnally applied a non-occluding sublingual relaxation splint combined with daily performed stretching exercises. Measurements were taken before treatment, after 4 weeks with no interventions (control period) and after 3 weeks, 3 and 6 months.

RESULTS

After the treatment mandibular opening range increased by 8mm (19%, p<0.05), lateral movement by 2.1mm (36%, p<0.05) while protrusive movement decreased by 0.5mm (p>0.05). Maximal and average velocity parameters significantly increased (p>0.05). These results were supported by the decrease in reported impairment and clinical pain occurrence (p<0.05). Only joint clicking change was non-significant (p>0.05).

CONCLUSIONS

Myorelaxation Therapy was effective in the treatment of our group of patients. A significant improvement in the opening and lateral movement range, as well as opening/closing velocity was obtained after 6 months of treatment. This method can be easily managed by general practitioner, especially in muscles-related TMD types.

Prosthodontic management of temporomandibular disorders

Temporomandibular disorders (TMD) are examined from a biopsychosocial or illness perspective. It is considered that TMD share features with many common chronic pain conditions. Functional disturbances of the masticatory system can be as complicated as the system itself. Although numerous treatments have been advocated, the complex nature of TMD requires a multidisciplinary team. Effective treatment selection begins with a thorough understanding of the disorder & its etiology. However, the multifactorial nature of this malady places some aspects of the disease beyond the traditional education of a Prosthodontist. The management goals for the Prosthodontist as a member of a TMD team are patient comfort, occlusal stability & the complex restoration of the teeth.

Occlusal stability

Occlusion is the foundation for clinical success in fixed, removable, and implant prosthodontic treatment. Understanding those principles is critical when restoring a patient's occlusion. Many philosophies, devices, and theories of occlusion have evolved based on anecdotal clinical observations and applied geometric perceptions. The literature has reported these classic and contemporary occlusal concepts. As evidence-based dentistry emerged, it championed scrutiny of previously held beliefs, resulting in the abandonment of many pragmatic, yet beneficial occlusal procedures. The impetus toward scientific discovery, whereby factual information might be universally applied in dental education and clinical practice, has renewed interest in occlusal studies.

New approaches to dental occlusion: a literature update

Because the study of occlusion is a basic area in dentistry, its components, physiology and integration with the stomatognathic system (SS) have been the subject of interest in the scientific literature. However, the focus given to this issue has changed substantially. Currently, new approaches have been proposed in order to update concepts and to demonstrate the full integration and functionality of this system within the human body. With this approach, the authors proposed the following literature review aimed at gathering recent papers (published from 2000 to 2010) with innovative study design, methodology and/or results. The authors' intention is to show the main trends in the study of occlusion and the SS. The literature review was conducted in the PubMed database, using initially the term "dental occlusion" as a key-word. As items of interest were found, papers were grouped by categories according to their main subject matter. Forty-seven articles were selected and the main categories obtained were: 1. functional magnetic resonance imaging (fMRI); 2. brain activation; 3. masticatory/occlusal function; 4. body function and physical performance; 5. osseoperception; 6. finite element models; and 7. occlusion and pain. Observing the current literature, the authors found that recent studies present different methodologies for the study of occlusion. These studies have allowed scientists to obtain detailed information about the physiology of occlusion and the SS, as well as about its integration in the body. Research in this area should be continued in order to clarify, in detail, the role of each component of the SS and its interaction with human physiology.

Bruxismo do sono: possibilidades terapêuticas baseadas em evidências

INTRODUÇÃO: o bruxismo do sono (BS) é uma desordem de movimentos estereotipados e periódicos, associados ao ranger e/ou apertar de dentes durante o sono, decorrentes da contração rítmica dos músculos mastigatórios. Essa condição não é uma doença, porém quando exacerbada pode ocasionar desequilíbrio e alteração das estruturas orofaciais. Dessa forma, surge a necessidade de se obter terapêuticas efetivas e seguras para o controle e o manejo do paciente bruxômano. As alternativas de tratamento variam desde terapêuticas orodentais e farmacológicas até técnicas comportamentais-cognitivas. OBJETIVOS: através de uma revisão sistemática da literatura, tendo como bases de pesquisa a Medline, Cochrane, Embase, Pubmed, Lilacs e BBO, no período compreendido entre 1990 e 2008, e com enfoque em estudos clínicos randomizados e quasi-randomizados, revisões sistemáticas e meta-análises, esse trabalho teve como objetivo analisar e discutir métodos de tratamento para o BS. RESULTADOS: pela análise da literatura verifica-se que existe uma grande quantidade de opções terapêuticas para o BS, porém muitas das terapias não têm suporte científico que as sustente. Assim, a escolha terapêutica deve ser pautada em evidências científicas e no bom senso clínico, objetivando uma melhora na qualidade de vida do paciente bruxômano.

Occlusal adjustment using the bite plate-induced occlusal position as a reference position for temporomandibular disorders: a pilot study

Background

Many researchers have not accepted the use of occlusal treatments for temporomandibular disorders (TMDs). However, a recent report described a discrepancy between the habitual occlusal position (HOP) and the bite plate-induced occlusal position (BPOP) and discussed the relation of this discrepancy to TMD. Therefore, the treatment outcome of evidence-based occlusal adjustments using the bite plate-induced occlusal position (BPOP) as a muscular reference position should be evaluated in patients with TMD.

Methods

The BPOP was defined as the position at which a patient voluntarily closed his or her mouth while sitting in an upright posture after wearing an anterior flat bite plate for 5 minutes and then removing the plate. Twenty-one patients with TMDs underwent occlusal adjustment using the BPOP. The occlusal adjustments were continued until bilateral occlusal contacts were obtained in the BPOP. The treatment outcomes were evaluated using the subjective dysfunction index (SDI) and the Helkimo Clinical Dysfunction Index (CDI) before and after the occlusal adjustments; the changes in these two indices between the first examination and a one-year follow-up examination were then analyzed. In addition, the difference between the HOP and the BPOP was three-dimensionally measured before and after the treatment.

Results

The percentage of symptom-free patients after treatment was 86% according to the SDI and 76% according to the CDI. The changes in the two indices after treatment were significant (p < 0.001). The changes in the mean HOP-BPOP differences on the x-axis (mediolateral) and the y-axis (anteroposterior) were significant (p < 0.05), whereas the change on the z-axis (superoinferior) was not significant (p > 0.1).

Conclusion

Although the results of the present study should be confirmed in other studies, a randomized clinical trial examining occlusal adjustments using the BPOP as a reference position appears to be warranted.

[Can orthodontic treatment generate temporomandibular disorders and pain? A review]

While considered for years to play the primary role in the etiology of temporo-mandibular joint disturbances (TMD), occlusal discrepancies are now considered to be just one causative factor among many. Recent studies, literature reviews or meta-analyses, and longitudinal studies with follow-up of children treated for many years all conclude that there is no risk of orthodontic treatment giving rise to episodes of temporo-mandibular disorders. The signs of TMD appearing during the course of orthodontic treatment should be considered in the context of the epidemiology of the disorder, which is characterized by a strong increase in its occurrence during adolescence. In conclusion, it should be stated that if orthodontic treatment can no longer be considered as one of the etiopathogenic factors in the TMD complex, there are no scientific arguments to justify the converse, that there are indications for orthodontic treatment whose sole goal would be the treatment of TMD.

A survey on German dentists regarding the management of craniomandibular disorders

The purpose of the present investigation was to identify the most frequent therapies and, in particular, the prescription patterns for occlusal splints for the management of craniomandibular disorders (CMDs) used by German general dentists and specialists. Additionally, the knowledge and opinion of the practising dentists were examined. All active members of the statutory dental insurance providers of the German North Rhine (n = 5,500) and the Westphalia-Lippe area (n = 4,984) were surveyed with a questionnaire by mail. Results indicated that occlusal splints were the first-choice therapy followed by physiotherapy and occlusal equilibration. In the preceding year, both general dentists and specialists made 30 occlusal splints on average. With regard to high-quality evidence-based recommendations, some statistically significant discrepancies between general dentists and specialists were detected. On the basis of the present data, it seems useful to consider intensifying the topic of CMDs and orofacial pain in future undergraduate dental curricula and in postgraduate training.

Bruxism physiology and pathology: an overview for clinicians

Awake bruxism is defined as the awareness of jaw clenching. Its prevalence is reported to be 20% among the adult population. Awake bruxism is mainly associated with nervous tic and reactions to stress. The physiology and pathology of awake bruxism is unknown, although stress and anxiety are considered to be risk factors. During sleep, awareness of tooth grinding (as noted by sleep partner or family members) is reported by 8% of the population. Sleep bruxism is a behaviour that was recently classified as a 'sleep-related movement disorder'. There is limited evidence to support the role of occlusal factors in the aetiology of sleep bruxism. Recent publications suggest that sleep bruxism is secondary to sleep-related micro-arousals (defined by a rise in autonomic cardiac and respiratory activity that tends to be repeated 8-14 times per hour of sleep). The putative roles of hereditary (genetic) factors and of upper airway resistance in the genesis of rhythmic masticatory muscle activity and of sleep bruxism are under investigation. Moreover, rhythmic masticatory muscle activity in sleep bruxism peaks in the minutes before rapid eye movement sleep, which suggests that some mechanism related to sleep stage transitions exerts an influence on the motor neurons that facilitate the onset of sleep bruxism. Finally, it remains to be clarified when bruxism, as a behaviour found in an otherwise healthy population, becomes a disorder, i.e. associated with consequences (e.g. tooth damage, pain and social/marital conflict) requires intervention by a clinician.

Efficacy of low-level laser therapy in the treatment of temporomandibular disorder

AIMS

To evaluate the effectiveness of low-level laser therapy (LLLT) in patients presenting with temporomandibular disorder (TMD) in a random and placebo-controlled research design.

METHODS

The sample consisted of 40 patients, divided into an experimental group (G1) and a placebo group (G2). The treatment was done with an infrared laser (830nm, 500mW, 20s, 4J/point) at the painful points, once a week for four consecutive weeks. The patients were evaluated before and after the treatment through a Visual Analogue Scale (VAS) and the Craniomandibular Index (CMI).

RESULTS

The baseline and posttherapy values of VAS and CMI were compared by the paired T-test, separately for the placebo and laser groups. A significant difference was observed between initial and final values (p < 0.05) in both groups. Baseline and post-therapy values of pain and CMI were compared in the therapy groups by the two-sample T-test, yet no significant differences were observed regarding VAS and CMI (p > 0.05).

CONCLUSION

After either placebo or laser therapy, pain and temporomandibular symptoms were significantly lower, although there was no significant difference between groups. The low-level laser therapy was not effective in the treatment of TMD, when compared to the placebo.

TMD and occlusion part II. Damned if we don't? Functional occlusal problems: TMD epidemiology in a wider context

OBJECTIVES

To review studies investigating how functional occlusion may relate to TMD and how bruxism may relate to TMD; to review the epidemiology of TMD and relate this to the context of clinical occlusal studies and other aetiological factors. Deficiencies in study design are highlighted and suggestions made to improve future study designs in order to provide an evidence-base for clinical practice.

DESIGN

Review article.

METHODS

Electronic databases (MEDLINE and the Cochrane Database of Systematic Reviews) were used to select relevant and frequently cited studies (mean: 40 citations). Citation rate was confirmed using the Web of Science. Study designs are reviewed and weaknesses and implications discussed.

RESULTS

Evidence is lacking to suggest functional occlusal factors cause TMD. Investigation of other aetiological factors has been relatively neglected.

CONCLUSIONS

Neither static nor dynamic occlusal factors (including orthodontics) can be said to 'cause' TMD. However, other potential aetiological factors exist which would benefit from more investigation. This, together with improved study designs, would help provide a stronger evidence-base for clinical practice in the future.

Subjective reactions to intervention with artificial interferences in subjects with and without a history of temporomandibular disorders

In a previous double-blind randomized controlled study, subjects with a history of temporomandibular disorder (TMD) reacted to artificial interference with more signs of TMD than did subjects with no TMD history. In the present study, we analysed the subjective reactions of these individuals on several symptom scales. Every day during the 2-week follow-up period, the subjects rated the intensity of their symptoms on 9 VAS scales (occlusal discomfort, chewing difficulties, tender teeth, fatigue in the jaws, headache, facial pain, opening difficulty, bruxism, ear symptoms). Subjects with a history of TMD and true interferences reported stronger symptoms than subjects with no TMD history and placebo interferences. The most prominent symptoms were occlusal discomfort and chewing difficulties. The difference in outcome between the groups with and without a TMD history suggests that there are individual differences in vulnerability to occlusal interferences. It is likely that the etiological role of occlusal interferences in TMD has not been correctly addressed in previous studies on artificial interferences.

Quantification of the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system

STATEMENT OF PROBLEM

There is no consensus on the association between occlusion and temporomandibular disorders (TMD).

PURPOSE

The purpose of this study was to quantify the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system.

MATERIAL AND METHODS

Eight occlusal features: retruded contact position (RCP) to maximum intercuspation (MI) slide length, vertical overlap, horizontal overlap, unilateral posterior reverse articulation, anterior open occlusal relationship, incisor dental midline discrepancy, mediotrusive interferences, and laterotrusive interferences, were clinically assessed by the same trained operator. The sample consisted of 81 women with a Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis I diagnosis of muscle disorder, for example myofascial pain, with or without limited opening, and 48 healthy women (control group). A stepwise multiple logistic regression was used to identify the significant associations between occlusal features and disease.

RESULTS

A slide from the retruded contact position to maximum intercuspation > or =2 mm and mediotrusive interferences were the only 2 occlusal features significantly associated with the presence of myofascial pain according to the RDC/TMD criterion symptoms. The odds ratio for myofascial pain was 2.57 for a slide from RCP to MI > or =2 mm and 2.45 for mediotrusive interferences. The percentage of the total log likelihood for myofascial pain explained by the significant occlusal factors amounted to 10.8% (Nagelkerke's R2=0.108). The multifactorial model, including the 2 significant occlusal factors, showed an acuracy to predict disease of 66.7% (sensitivity 71.6%; specificity 58.3%).

CONCLUSION

Occlusal features showed a low predictive value to detect muscle disorders of the stomatognathic system. Multifactorial complex pathologies, such as TMD, should be studied using multivariate statistical analyses, as univariate models may overestimate some resulting associations.

[Chronic temporomandibular disorders]

According to the 3rd German Oral Health Study (1999), the prevalence of painful temporomandibular disorders (TMDs) is about 5%. Although limited information about the magnitude of utilization of health care services and expenses for health care in temporomandibular pain patients is available, the financial burden of affected individuals may be considerable. The etiology and pathophysiology of chronic TMDs is still obscure. However, certain (patho)physiological mechanisms may be associated with the genesis and perpetuation of these musculoskeletal facial pains (e. g. disturbances in central nervous system processing; psychosocial factors; hormonal influences). Strong scientific evidence from the dental/medical literature is currently available for the following forms of TMD treatment and management: occlusal appliances (stabilization appliance), clonazepam, diazepam, meprobamate, EMG biofeedback, multimodal approaches (somatic and psychological pain management).

Efficacy of stabilization splints for the management of patients with masticatory muscle pain: a qualitative systematic review

This study aimed at providing an answer to two clinical questions related to patients with masticatory muscle pain: 1) Does the use of a full-coverage hard acrylic occlusal appliance (stabilization splint) lead to a significant decrease of symptoms? and 2) Is the treatment success achieved with a stabilization splint more pronounced than the success attained with other forms of treatment (including placebo treatment) or no treatment? A systematic search was carried out in different electronic databases, supplemented by handsearch in four selected dental journals and by examination of the bibliographies of the retrieved articles. Thirteen publications, representing nine controlled clinical studies, could be identified. Reporting quality of most studies as assessed with the Jadad score ranged from 1 to 5. Based on the currently best available evidence it appears that most patients with masticatory muscle pain are helped by the incorporation of a stabilization splint. Nevertheless, evidence is equivocal if improvement of pain symptoms after incorporation of the intraoral appliance is caused by a specific effect of the appliance. A stabilization splint does not appear to yield a better clinical outcome than a soft splint, a non-occluding palatal splint, physical therapy, or body acupuncture. The scarcity of current external evidence emphasizes the need for more and better clinical research.

Occlusal adjustment for treating and preventing temporomandibular joint disorders

To assess the effectiveness of occlusal adjustment (OA) for treating temporomandibular disorders (TMD) in adults and preventing TMD. The Cochrane Controlled Trials Register, MEDLINE and EMBASE were comprehensively searched using the Cochrane methods. Reports and review articles were retrieved. Unpublished reports or abstracts were considered from the SIGLE database. All randomized or quasi-randomized controlled trials comparing OA with placebo, reassurance or no treatment in adults with TMD. The outcomes were global measures of symptoms, pain, headache and limitation of movement. Data collection and analysis followed the Cochrane Oral Health Group's statistical guidelines. Results showed no difference between OA and control group in symptom-based outcomes for treatment or incidence of symptoms for prevention. There is no evidence that OA treats or prevents TMD. OA cannot be recommended for the management or prevention of TMD. Future trials should use standardized diagnostic criteria and outcome measures when evaluating TMD.

Effect of artificial occlusal interferences depends on previous experience of temporomandibular disorders

Studies on artificial interferences in subjects with no temporomandibular (TMD) history have shown adaptation to the interference within a fairly short period of time. The role of occlusal factors in the etiology of TMD has therefore been questioned. The results might have been different, however, if subjects with a prior TMD history had been included in the study groups. To test this assumption in a randomized double-blind clinical set-up, we included healthy women without (n = 26) as well as with (n = 21) an earlier TMD history. Both groups were randomly divided into true and placebo interference groups. Artificial interferences were introduced in the true interference groups and simulated in the placebo groups. The subjects were followed for 2 weeks, after which the interferences were removed. The subjects without a TMD history showed fairly good adaptation to the interferences, but the subjects with a TMD history and true interferences showed a significant increase in clinical signs compared to the other groups. We suggest that the etiological role of occlusal interferences in TMD may not have been correctly addressed in previous studies with artificial interferences and allow no conclusions as regards TMD etiology.

Occlusion and temporomandibular disorders (TMD): still unsolved question?

The rejection of the occlusal hypothesis cannot be justified with the present empirical evidence.