Importance Of Occlusion And Physiological Significance Of Sleep Bruxism Shouichi Miyawaki. Episode 59. IOC 2020

Relationship between occlusion and digestive tract

• Mastication supresses initial gastric emptying Takada 2012
• Malocclusion reduces masticatory function, reduces gastric emptying rate, as it takes longer to eat Koike 2018
• Gastroesophageal reflux (GERD) in class 3 malocclusion was greater than normal subjects, and reduce bite force Togawa 1991
• GERD caused by transient lower esophageal sphincter relaxation
  • GERD can lead to heartburn and cancer
  • Common in elderly population
  • Erosive wear to the teeth

Sleep Bruxism SB

• Results in tooth wear
  • 40% of non-bruxists also have signs of tooth wear
• Abfraction lesions
• Broken prosthesis
• Gingival recession
• Headaches 65% of bruxists
• Bruxism is associated with TMD Systematic review Jimenez-Silva 2017
• Bruxism increase risk of TMD by 4-8 times due to anterior disk displacement Huang 2003
• Hypoertrophy of masseter muscle

Risk of SB

• Associated factors of SB
  • OSA
  • Micro arousal 90%
  • Phycological stress

Causes of sleep bruxism

• Was considered to be malocclusion – peripheral theory discredited – Greene 1982, Rugh 1985
• Sensing by the periodontal membrane = modify muscle activity Lavigne 2000
  • = CNS cause of bruxism
  • But unclear mechanism so considered multifactorial model
• SB greater swallowing Miyawaki 2003
  • Increase in swallowing = increase in GER Miyawaki 2004

Theory of GER and SB and malocclusion

• GER = microarousal = bruxism = increase swallowing = worsen GER
  • 73% of GERD patients had SB Mengatto 2013
  • SB strong association with GERD (OR 4.3), systematic review Castroflorio 2017
• Theory = malocclusion – GERD
• Bruxism is a mechanism of the body to protect itself from GER – by increasing saliva and swallowing. Miyawaki