Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism

Inspired by the international consensus on defining and grading of bruxism (Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ et al. J Oral Rehabil. 2013;40:2), this commentary examines its contribution and underlying assumptions for defining sleep bruxism (SB). The consensus’ parsimonious redefinition of bruxism as a behaviour is an advance, but we explore an implied question: might SB be more than behaviour? Behaviours do not inherently require clinical treatment, making the consensus‐proposed ‘diagnostic grading system’ inappropriate. However, diagnostic grading might be useful, if SB were considered a disorder. Therefore, to fully appreciate the contribution of the consensus statement, we first consider standards and evidence for determining whether SB is a disorder characterised by harmful dysfunction or a risk factor increasing probability of a disorder. Second, the strengths and weaknesses of the consensus statement's proposed ‘diagnostic grading system’ are examined. The strongest evidence‐to‐date does not support SB as disorder as implied by ‘diagnosis’. Behaviour alone is not diagnosed; disorders are. Considered even as a grading system of behaviour, the proposed system is weakened by poor sensitivity of self‐report for direct polysomnographic (PSG)‐classified SB and poor associations between clinical judgments of SB and portable PSG; reliance on dichotomised reports; and failure to consider SB behaviour on a continuum, measurable and definable through valid behavioural observation. To date, evidence for validity of self‐report or clinician report in placing SB behaviour on a continuum is lacking, raising concerns about their potential utility in any bruxism behavioural grading system, and handicapping future study of whether SB may be a useful risk factor for, or itself a disorder requiring treatment.     

Is sleep bruxism related to the levels of enzymes involved in the serotonin synthesis pathway?

Clinical Oral Investigations - This exploratory research aimed to evaluate the levels of tryptophan hydroxylase 1 (TPH1) and aromatic l-amino acid decarboxylase (DDC), which play an important role...     

Are bruxism and the bite causally related?

In the dental profession, the belief that bruxism and dental (mal-)occlusion ('the bite') are causally related is widespread. The aim of this review was to critically assess the available literature on this topic. A PubMed search of the English-language literature, using the query 'Bruxism [Majr] AND (Dental Occlusion [Majr] OR Malocclusion [Majr])', yielded 93 articles, of which 46 papers were finally included in the present review*. Part of the included publications dealt with the possible associations between bruxism and aspects of occlusion, from which it was concluded that neither for occlusal interferences nor for factors related to the anatomy of the oro-facial skeleton, there is any evidence available that they are involved in the aetiology of bruxism. Instead, there is a growing awareness of other factors (viz. psychosocial and behavioural ones) being important in the aetiology of bruxism. Another part of the included papers assessed the possible mediating role of occlusion between bruxism and its purported consequences (e.g. tooth wear, loss of periodontal tissues, and temporomandibular pain and dysfunction). Even though most dentists agree that bruxism may have several adverse effects on the masticatory system, for none of these purported adverse effects, evidence for a mediating role of occlusion and articulation has been found to date. Hence, based on this review, it should be concluded that to date, there is no evidence whatsoever for a causal relationship between bruxism and the bite.     

What is the cause of failure of local anesthesia?

Local anesthesia fails in 10% of cases of inferior alveolar nerve block and 7% of all cases of local anesthesia in general practice. Possible causes of failure are infection, wrong selection of local anesthetic solution, technical mistakes, anatomical variations with accessory innervation and anxiety of the patient. In this publication we discuss reasons for frequent failure in case of infection and in inferior alveolar nerve block. Understanding the mechanism of failure in local anesthesia, makes it possible to formulate guidelines to guarantee success. These measures are discussed in detail.     

The microbiology of oral lichen planus: Is microbial infection the cause of oral lichen planus?

Oral lichen planus (OLP) is a variant of lichen planus (LP), a common chronic mucocutaneous inflammatory disease. Cutaneous lesions of LP are self‐limiting, but OLP lesions are non‐remissive, alternating periods of exacerbation and quiescence, and only symptomatic treatments exist for OLP. The precise etiology and pathogenesis of OLP are hardly understood, which is a major obstacle to the development of new therapeutics for this disease. OLP is considered a T‐cell‐mediated inflammatory disease. Although various antigens have been considered, what actually triggers the inflammatory response of T cells is unknown. Suggested predisposing factors include genetic factors, stress, trauma, and infection. The aim of this review was to determine whether microbial infection can cause OLP. We first reviewed the association between OLP and microbial factors, including viral, fungal, and bacterial infections. In addition, each microbial factor associated with OLP was assessed by modified guidelines of Fredricks and Relman to determine whether it establishes a causal relationship. In conclusion, no microbial factor yet fulfills the guidelines to establish the causality of OLP. By focusing on the unclarified issues, however, the potential roles of microbial factors in the pathogenesis of OLP will be soon elucidated.     

Is bruxism severity a predictor of oral splint efficacy in patients with myofascial face pain?

Both the efficacy and mechanism of any effect of oral splint therapy for patients with temporomandibular disorders (TMDs) are a matter of controversy. To address these issues, this study tested the hypothesis that oral splints produce the most marked pain relief for those TMD patients with myofascial face pain (MFP) who also brux (i.e. grind or clench) more than other MFP patients. In a 6-week randomized controlled clinical trial, 52 women with MFP were randomly assigned to receive either a full-coverage hard acrylic splint or a palatal-only splint. Bruxism was assessed both by self-report and by an objective assessment of molar microwear changes over a 2-week period prior to the start of the trial. Tested across multiple outcome measures, results indicated that those receiving the full-coverage splint had marginally better improvement on some pain-related measures than those receiving the palatal splint, but severity of bruxism did not moderate the therapeutic effect of the full-coverage splint. These findings strongly argue against the belief that oral splints reduce MFP by reducing bruxism and raise questions about the importance of bruxism in the maintenance of MFP.     

Is the consumption of fruit cariogenic?

Aim: The aim of this study was to investigate possible risk factors for dental caries in primary school children. Methods: Children aged 10–12 years (n = 257) residing in Lithgow, a non‐fluoridated community in New South Wales, Australia, were examined for caries experience in the permanent dentition. Information on dental practices, diet, residential movements, and socioeconomic status were obtained from self‐completed questionnaires. Results: Caries risk in the permanent teeth was associated with social disadvantage and diet. Among the dietary factors, the frequency of fruit consumption was associated with higher odds of caries experience (odds ratio: 1.52, 95% confidence intervals: 1.05, 2.21). Conclusions: Exposure to a high level of fruit consumption was suggestive of increased caries risk. Longitudinal studies are required to investigate the relationship between fruit consumption and dental caries.     

Hyperaeration of the sphenoid sinus: cause for concern?

A case of exuberant pneumatization of the left sphenoid sinus into the pterygoid process and floor of the middle cranial fossa is presented. The fact that pneumatization of the sphenoid sinus is frequently atypical is of clinical import because there is an intimate relationship between the contents of a hyperaerated sinus and adjacent vital facial and cranial structures. It is imperative that clinicians determine the location and extent of the walls of the sphenoid sinus and its relationship to adjacent vital structures whenever endoscopic sinus surgery is contemplated to avoid morbid consequences during surgery.     

Review article. Are bruxism and the bite causally related?

There is an increasing 'acceptance of a multicausal, non-occlusion-oriented aetiology of bruxism.'     

Is arthrocentesis plus hyaluronic acid superior to arthrocentesis alone in the treatment of disc displacement without reduction in patients with bruxism?

PurposeThis study was designed to investigate the efficacy of arthrocentesis with and without intra-articular injection of hyaluronic acid (HA) in the treatment of disc displacement without reduction (DDwoR) in patients with bruxism.Materials and methodsA retrospective cohort study was conducted using the files of patients with DDwoR, limited mouth opening, and bruxism. Patients were divided into two groups according to the treatment method: arthrocentesis alone (group 1) and arthrocentesis plus intra-articular HA injection (group 2). To evaluate the clinical outcomes for the groups, maximum mouth opening (MMO) and visual analog scale (VAS) values before treatment, immediately after the operation, and at 1, 3, 6, 9, and 12 months postoperatively were analyzed.ResultsThe study consisted of 40 patients (34 female and 6 male, mean age 36.0 ± 11.95 years). MMO values increased and VAS scores decreased in both groups at all follow-ups after the treatment compared with pretreatment values (p < 0.001). The increase in MMO in group 2 was greater than in group 1 only at 3 and 6 months postoperatively (p = 0.013 and 0.009, respectively).ConclusionsIntra-articular HA injection is not a relevant addition when arthrocentesis is performed and a stabilizing splint is used.     

Is segmental osteotomy of the jaws outdated?

In earlier days segmental osteotomies had a broad field of indications. In the era of combined surgical-orthodontic treatments, they are pushed far into the background. This article shows that this development is unjust. If carefully indicated, segmental osteotomies still have a well-defined place in our armory of surgical interventions. With their elegance and the compulsion to respect detail they are not only of marked didactic value, but they also fill a gap, especially in the treatment options for the lower jaw. Far from being obsolete, they should still belong to the routine options when orthognathic surgery is considered.     

Can cystic lesions of the jaws be considered as the cause of mandibular asymmetry?

Background The aim of this study is to investigate the presence of condylar and ramal asymmetry in patients with a cyst larger than 10 mm in the maxilla or mandible.Material and Methods Condylar and ramal asymmetry index measurements of 47 patients (mean age: 28.85 ± 15.348) in the study group and 40 patients in the control group (mean age: 33.73 ± 13.095) were performed using panoramic radiographs. The study group consists of patients with cysts larger than 10 mm in diameter in the maxilla or mandible. The control group consisted of patients with no radiolucent lesions and no history of trauma. The possible statistical difference between the groups was evaluated by the Mann-Whitney U test.Results No statistically significant difference was observed in asymmetry indices according to gender and the jaw (maxilla or mandible) in which the cyst was located. However, it was determined that CAI and RAI values were statistically significantly different between the study and control groups (p = 0.047 and p = 0.016, respectively).Conclusions The presence of intraosseous cysts larger than 10 mm in the jaws was found to be associated with condylar and ramal asymmetry. Key words:Condylar asymmetry, ramal asymmetry, odontogenic cysts