Functional Significance Of The Mouth

31.3.06

The oral cavity
Tissues
• Bone.
• Joint(s).
• Epithelia.

Borders
• Lips.
• Palatoglossal fold.
• Palate.
• Cheeks.
• Floor of mouth.

Lips
• Muscular structures.
• Non-keratinised oral mucous membrane.
• Angle of mouth.

Cheeks
• Muscular structures.
• Non-keratinised oral mucous membrane.
• Buccinator muscle.

Tongue
• Dorsum.
• Ventral (inferior) surface.
• Lateral borders.

Dorsum of tongue
• Anterior two-thirds - sensory (V), taste (VII).
• Posterior one-third - IX.

Tongue muscles
• Extrinsic - genioglossus, hyoglossus, palatoglossus.
• Intrinsic - superior longitudinal, inferior longitudinal, vertical, transverse.

Functions
• Mastication.
• Speech.
• Taste.
• Oral hygiene.
• Communication (gestures).
• Sensory (infant).

Hard palate
• Maxilla and palatine bones.
• Thick keratinised epithelium.

Soft palate

Salivary glands
• Minor salivary glands - everywhere.
• Major salivary glands.
-Parotid (25% - mainly serous).
-Submandibular (70% - mixed saliva).
-Sublingual (5% - mainly mucous).

Muscles of mastication
• Temporalis.
• Masseter.
• Medial pterygoid.
• Lateral pterygoid.
• Accessory muscles of mastication.

Temporomandibular joint
• TMJ = synovial joint with intervening disc.
• Disc divides joint ccavity into 2.

Nerve supply to muscles of mastication
• All V apart from buccinator (VII).

Nerve supply to oral cavity
• V (trigeminal).
-Ophthalmic branch.
-Maxillary branch.
-Mandibular branch.

Blood supply to oral cavity = internal carotid and its branches.

Saliva
Protective functions
• Lubrication - mucins, glycoproteins, water.
• Antimicrobial.
-Amylase - breaks up starch.
-Complement.
-Lysozyme.
-Secretory IgA.
• Contains growth factors - healing.
• Maintains mucosal integrity.
• Lavage/cleansing/clearance of sugars and acids.
• Buffering.
• Remineralisation.

Food- and speech-related functions
• Food preparation - water, mucins.
• Digestions - amylases.
• Taste.
• Speech.

Considerable volume produced each day: 0.5-0.75l.

Salivary gland anatomy

Secretory unit
• Acini.
• Ducts.

Parotid gland
• VII branches divide gland into superficial and deep lobes, while moving from stylomastoid foramen to muscles of facial expression.

Salivary constituents
• Ions - Na+, K+, Ca2+, PO4-, Fl-, Cl-.
• Miscellaneous.
-Blood and blood-derivative compounds.

Factors contributing to saliva content
• Normal human variability.
• Unstimulated versus stimulated saliva.
• Ageing (not per se, but medications of ageing do).
• Medications - 500 that cause dry mouth (xerostomia).
• Disease.
• Circadian rhythms.

Factors affecting salivary production
• Local diseases.
• Systemic diseases.
• Medication.

Salivary dysfunction and oral sequelae
• Dental caries.
• Mucositis.
• Oral ulceration.
• Taste.
• Swallowing.
• Dentures - loose and painful.
• Infections.

Dental anatomy
Human dentition
• 32 permanent, 20 primary.

Incisors
• Straight edges.
• Designed to cut through food.

Canines
• Function: pierce and hold food.
• Located at corners of mouth.

Premolars
• Some characteristics of both canines and molars.
• Located between canines and molars.

Molars
• Crush and grind food.
• Located at back of mouth.
• First, second and third molars.

Tooth surfaces
• Proximal.
• Lingual.
• Facial.
• Incisal/buccal.

Enamel
• Covers crown.
• Hardest substance in human body.
• Highly mineralised.
• Brittle.
• After initial completion, new enamel cannot be formed.

Dentine
• Largest component of tooth.
• Contributes to tooth colour.
• Can form throughout life - reparative dentine.
• Structure: dentinal tubules.

Cementum
• Covers root.
• Formed continuously throughout life.

Dental pulp
• Soft tissue.

Supporting structures (periodontium)
• Cementum, periodontal ligament, gingivae, alveolar bone.

Dental x-rays
1. Bitewing - check for dental caries in back teeth.
2. Periapical - whole-tooth radiograph.
Panaramic view (orthopantomogram - OPG) - plan view of all teeth - MOST IMPORTANT.

Formation of teeth
• Entire primary dentition begins at 6-8 weeks in utero.
• Successional secondary dentition begins at ≈20 weeks in utero.
• Stages of crown development.
• Dental lamina/tooth bud.
-Extends in from lamina.
-Enamel organ formation - will mineralise.
-Cap stage.
• Initial amelo- and dentinogenesis.
• Ameloblasts and odontoblasts.

Tooth eruption dates

And bytheway, I have complete faith in Paul Collingwood.