Mastication, Deglutition, & Dysphagia

Mastication, Deglutition, & Dysphagia

• Mastication is the process of chewing food, preparing it for swallowing and digestion.
• Chewing breaks down food into smaller pieces.
• Teeth, tongue, muscles of mastication, and lips all play roles in mastication.
• Teeth physically tear, rip, and grind food down.
• Tongue moves food around.
• Muscles of mastication (e.g., masseter) move the mandible to chew.
• Lips hold food in place.
• A deficiency in any of these structures potentially impacts a patient's ability to eat.
• The masticatory cycle occurs in three phases.
  • Opening phase: depressor muscles of the jaw contracts, opening the mouth.
  • Closing phase: elevator muscles of the jaw work to close the mouth.
  • Occlusal phase: contact of mandibular and maxillary teeth through the action of isometric muscles.
• Saliva containing amylase begins the digestive process.
• Food is broken down, mixed with saliva to form a bolus ready for swallowing.
• The length of time food stays in the mouth depends on its consistency.

Deglutition (The Normal Swallow)

• Deglutition is the process of swallowing.
• The action of swallowing involves 7 stages.
  • Oral phase (voluntary)
  • Pharyngeal phase (involuntary):
  • Esophageal phase (involuntary)
• The oral phase involves:
  • Lips closing.
  • Tongue pressing bolus of food.
  • Bolus moved toward the back of the mouth.
• The pharyngeal phase involves:
  • Soft palate rising to block the nasopharynx.
  • Epiglottis covering airway
  • Vocal cords closing over the trachea (breathing stops).
  • Food being pushed down the pharynx.
• The esophageal phase involves:
  • Peristaltic waves moving the bolus along the esophagus toward the stomach.
  • Cardiac sphincter opening to allow food into the stomach.
• Two types of swallowing:
  • Automatic (dry).
  • Voluntary (food and drink).
• Swallowing is initiated by tactile stimulation in the oropharynx.
• 25 skeletal muscles work together in the process of swallowing
• Multiple components working together, including arousal of appetite, saliva flow, taste buds, and food stimuli influence the process of swallowing.

Swallowing Structures

• Lips
  • Essential for creating intra-oral pressure.
• Tongue
  • Shapes and moves bolus of food.
• Soft palate
  • Blocks nasopharynx.
• Hyoid bone
  • Supports and gives origin attachment to muscles.
• Epiglottis
  • Protects airway.
• Vocal cords
  • Close the airway.
• Cricoid cartilage
  • Relax to allow food to enter the esophagus.

Phases of Swallowing

• Three phases: Oral, pharyngeal, esophageal.

Ninja Nerd Lectures & Sam Webster Video

• Ninja Nerd provides a detailed overview of swallowing stages using diagrams.
• Sam Webster's video uses anatomical models for a 3-dimensional perspective.

Swallowing Occurs in Three Phases

• Oral phase (Voluntary): initiates the process.
• Pharyngeal phase (Involuntary):
• Esophageal phase (Involuntary): Food is transported from the pharynx to the stomach.

Oral Phase (feeding stage).

• Lips close and prepare bolus mastication and drenching in saliva shaping the bolus.
• Nasal breathing continues.
• Larynx is open.
• Hypopharyngeal sphincter is closed.
• Voluntary stage can be stopped at will.
• Food positioned in the front of the mouth.

Oral Phase (Executive Phase).

• Begins when the bolus is projected past the pillars of the fauces toward the pharynx.
• The soft palate rises and blocks off the nasopharynx.
• Respiration ceases.

Pharyngeal Phase (Swallowing Phase)

• Swallow reflex is triggered by receptors.
• Breathing and nasal passage close.
• Larynx is elevated.
• Glottis closes.
• Bolus moves lower.

Oesophageal Phase

• Bolus transported down the esophagus to the stomach by peristaltic waves.

Nerve Innervation

• Nerves involved in sensation and motor control.

Dysphagia (Swallowing Difficulties)

• Difficulty swallowing, a medical disorder.
• Common causes include throat infection, inflammatory swelling, weakened muscles/nerves.
• Possible signs: food/drink going down the wrong way, coughing, feeling food stuck, still having food/drink in the mouth.

Causes of Dysphagia

• Weakening/damaging of muscles/nerves in the swallowing process.
• Stroke, cerebral palsy, parkinson's disease, cleft palate, bony outgrowths.
• Head/neck cancer, infections, dementia, medication/alcohol use, and age-related changes.

Disorders of the Pharyngeal Stage

• Delayed swallow reflex leads to material entering the pharynx before the reflex is triggered.
• Reduced pharyngeal peristalsis causes residue to be in the pharynx after the swallowing process is completed.

Disorders of the Oesophageal Stage

• Reduced peristalsis causes material to reflux leading to aspiration.
• Poor patient positioning during mealtimes is another possible risk for aspiration.

Abnormal Swallow [Associated Problems]

• Issues related to abnormal swallowing.

Infection

• Aspiration occurs if food/liquid enters the larynx.
• Food/liquid entering larynx can cause chest infection.

Dehydration

• Difficulty safely swallowing can cause inadequate fluid intake.
• Dehydration is a potential complication, leading to reduced saliva flow, susceptibility to infections, and potential mental confusion.

Malnutrition

• Inability to swallow safely can cause malnutrition due to insufficient intake.
• Fear of choking, embarrassment, and social withdrawal can negatively impact mealtimes and reduce nutrition.

Gastric Reflux and Heartburn

• Stomach contents return to the lower esophagus due to reflux peristalsis.
• Stratified squamous epithelium in the esophagus is not protective against stomach acid; this can result in inflammation and ulceration.
• Symptoms include burning pain in the epigastrium and behind the sternum.

Dental Management of Dysphagia

• Dental impacts from dysphagia: reduced oral clearance, increased plaque/calculus deposits, dry mouth, and increased caries risk.
• Considerations: patient assessment, positioning, preventative advice, treatment provision, and additional considerations.

Additional considerations

• Patient assessment: Determine if dysphagia is part of wider condition; extent of dysphagia; altered diet/oral hygiene; and day-to-day impact on patient.
• Patient positioning: Comfortable and safe position for dental treatment.
• Preventative advice: Recommend non-foaming toothpastes, avoid wetting toothbrushes, avoid mouthwashes; use aspirating toothbrushes, diet analysis and advice.
• Provision of treatment: Careful use of water with power driven scaler instruments, 3-in-1 and fast handpieces, use of good suction and rubber dam protocols, and appropriate materials for dental procedures.
• Additional considerations: Need for liquid preparations if nitrous oxide required. Care with viscosity; communication/signalling; breaks; and patient's ability to swallow saliva.

Additional Resources

• Provides resources such as leaflets, YouTube videos, and websites for further learning.

Explore the intricate processes of mastication, deglutition, and dysphagia. This quiz covers the anatomy and physiology involved in chewing, swallowing, and the potential issues that arise when any part of these processes is impaired. Test your knowledge on how food is prepared for digestion and its subsequent journey.