title: Theories on possible temporal relationships between sleep bruxism and obstructive sleep apnea events. An expert opinion.
abstract: BACKGROUND
  Sleep bruxism (SB) is a term covering different motor phenomena with various risk and etiological factors and potentially different clinical relevance, especially as far as its possible protective role against obstructive sleep apnea (OSA) is concerned. The present expert opinion discusses the possible temporal relationships between the two phenomena.
  
  
  METHODS
  Four hypothetical scenarios for a temporal relationship may be identified: (1) the two phenomena are unrelated; (2) the onset of the OSA event precedes the onset of the SB event within a limited time span, with SB having a potential OSA-protective role; (3) the onset of the SB event precedes the onset of the OSA event within a limited time span, with SB having an OSA-inducing effect; and (4) the onset of the OSA and SB event occurs at the same moment.
  
  
  RESULTS
  Literature findings on the SB-OSA temporal relationship are inconclusive. The most plausible hypothesis is that the above scenarios are all actually possible and that the relative predominance of one specific sequence of events varies at the individual level. SB activity may be protective against OSA by protruding the mandible and restoring airway patency in those subjects who benefit from mandibular advancement strategies or may even be related to OSA induction, as a consequence of airways' mucosae swelling resulting from a SB-induced trigeminal cardiac reflex.
  
  
  CONCLUSIONS
  Clinicians should keep in mind that the SB-OSA relationship is complex and that interindividual differences may explain the possible different SB-OSA relationships, with particular regard to the anatomical site of obstruction.
authors: Temporomandibular Disorders Clinic, Department of Maxillofacial Surgery, University of Padova, Padova, Italy. daniele.manfredini@tin.it.
authors: Daniele
authors: D
authors: Manfredini
authors: Temporomandibular Disorders Clinic, Department of Maxillofacial Surgery, University of Padova, Padova, Italy.
authors: Luca
authors: L
authors: Guarda-Nardini
authors: Institute of Otolaryngology, Department of Neurosciences, University of Padova, Padova, Italy.
authors: Rosario
authors: R
authors: Marchese-Ragona
authors: Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.
authors: Frank
authors: F
authors: Lobbezoo
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D009129:Muscle Tonus / Q000502:physiology; D017286:Polysomnography; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D020186:Sleep Bruxism / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D013223:Statistics as Topic; D013997:Time Factors
keywords: Bruxism; Obstructive sleep apnea; Relationship; Sleep bruxism