Effect of mechanical loading on the metabolic activity of cells in the temporomandibular joint: a systematic review

Clin Oral Investig. 2018 Jan;22(1):57-67. Date Added: June 12, 2018

By: Betti BF, Everts V, Ket JCF, Tabeian H, Bakker AD, Langenbach GE, and Lobbezoo F.

The purpose of this systematic review was to elucidate how different modalities and intensities of mechanical loading affect the metabolic activity of cells within the fibro-cartilage of the temporomandibular joint (TMJ).

A systematic review was conducted according to PRISMA guidelines using PubMed, Embase, and Web of Science databases. The articles were selected following a priori formulated inclusion criteria (viz., in vivo and in vitro studies, mechanical loading experiments on TMJ, and the response of the TMJ). A total of 254 records were identified. After removal of duplicates, 234 records were screened by assessing eligibility criteria for inclusion. Forty-nine articles were selected for full-text assessment. Of those, 23 were excluded because they presented high risk of bias or were reviews. Twenty-six experimental studies were included in this systematic review: 15 in vivo studies and 11 in vitro ones.

The studies showed that dynamic mechanical loading is an important stimulus for mandibular growth and for the homeostasis of TMJ cartilage. When this loading is applied at a low intensity, it prevents breakdown of inflamed cartilage. Yet, frequent overloading at excessive levels induces accelerated cell death and an increased cartilage degradation.

Knowledge about the way temporomandibular joint (TMJ) fibrocartilage responds to different types and intensities of mechanical loading is important to improve existing treatment protocols of degenerative joint disease of the TMJ, and also to better understand the regenerative pathway of this particular type of cartilage.

Does Snoring Time Always Reflect the Severity of Obstructive Sleep Apnea?

Ann Otol Rhinol Laryngol. 2017 Oct;126(10):693-696 | Date Added: June 12, 2018

By: Hong SN, Yoo J, Song IS, Joo JW, Yoo JH, Kim TH, Lee HM, Lee SH and Lee SH.

Although it is commonly believed that the degree of snoring reflects the severity of obstructive sleep apnea (OSA), there is often a mismatch between the improvement in OSA and the decrease of snoring time following OSA treatment. The aim of this study was to determine the relationship between OSA severity and snoring time.

A total of 280 subjects who complained of snoring were divided by apnea-hypopnea index (AHI) into 5 groups. The snoring rate (the amount of sleep time spent snoring divided by the total sleep time) and the clinical data including polysomnographic findings were compared and analyzed.

There was no significant correlation between AHI and snoring rate (r = -0.038, P = .524). The snoring rate in the control group was significantly lower than that in the moderate ( P < .001) and severe ( P = .003) groups. The snoring rate in the very severe group was significantly lower than those in the mild ( P < .001), moderate ( P < .001), and severe ( P < .001) groups. However, there was no significant difference between snoring rates in the control group and the very severe group ( P = .832).

The change in snoring rate according to the severity of AHI showed an inverted U-shaped pattern, with a peak in the moderate OSA group.

Archived Articles

Chronic orofacial pain

Oral Dis. 2017 Jul;23(5):566-571. | Date Added: June 12, 2018

By: Renton T.

The issues specific to trigeminal pain include the complexity of the region, the problematic impact on daily function and significant psychological impact (J Dent, 43, 2015, 1203). By nature of the geography of the pain (affecting the face, eyes, scalp, nose, mouth), it may interfere with just about every social function we take for granted and enjoy (J Orofac Pain, 25, 2011, 333). The trigeminal nerve is the largest sensory nerve in the body, protecting the essential organs that underpin our very existence (brain, eyes, nose, mouth). It is no wonder that pain within the trigeminal system in the face is often overwhelming and inescapable for the affected individual.

Temporomandibular disorders and dental occlusion

J Oral Rehabil. 2017 Nov;44(11):908-923 | Date Added: June 12, 2018

By: Manfredini D, Lombardo L, and Siciliani G.

To answer a clinical research question: 'is there any association between features of dental occlusion and temporomandibular disorders (TMD)?' A systematic literature review was performed. Inclusion was based on: (i) the type of study, viz., clinical studies on adults assessing the association between TMD (e.g., signs, symptoms, specific diagnoses) and features of dental occlusion by means of single or multiple variable analysis, and (ii) their internal validity, viz., use of clinical assessment approaches to TMD diagnosis. The search accounted for 25 papers included in the review, 10 of which with multiple variable analysis. Quality assessment showed some possible shortcomings, mainly related with the unspecified representativeness of study populations. Seventeen (N = 17) articles compared TMD patients with non-TMD individuals, whilst eight papers compared the features of dental occlusion in individuals with TMD signs/symptoms and healthy subjects in non-patient populations. Findings are quite consistent towards a lack of clinically relevant association between TMD and dental occlusion. Only two (i.e., centric relation [CR]-maximum intercuspation [MI] slide and mediotrusive interferences) of the almost forty occlusion features evaluated in the various studies were associated with TMD in the majority (e.g., at least 50%) of single variable analyses in patient populations. Only mediotrusive interferences are associated with TMD in the majority of multiple variable analyses. Such association does not imply a causal relationship and may even have opposite implications than commonly believed (i.e., interferences being the result, and not the cause, of TMD). Findings support the absence of a disease-specific association. Based on that, there seems to lack ground to further hypothesise a role for dental occlusion in the pathophysiology of TMD. Clinicians are encouraged to abandon the old gnathological paradigm in TMD practice.

Current Articles on Orofacial Pain & Related Topics

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