SKA Week 7:

Salivary Glands

Salivary gland structure:

• acini produce saliva

• secreted into ducts within fleshy part of gland (parenchyma)

3 Major Salivary Glands:

1. Parotid gland = stensen’s duct

   • stenson’s duct opens opposite of the second upper molar

2. Submandibular gland = wharton’s ducts

   • wharton’s duct runs above the mylohyoid muscle and opens under the tongue

   • mixed saliva (serous + mucous) (7:3)

3. Sublingual gland = rivinus duct

   • rivinus ducts sits between the mucosa and mylohyoid muscle

Functions of Salivary Glands

Salivary glands play a crucial role in maintaining oral and overall health. Their primary functions include:

1.   Lubrication & Protection

• Mucous secretion keeps the oral mucosa moist, preventing dryness and irritation.

• Forms a protective barrier against mechanical injury, pathogens, and toxins.

2.  Digestion

• Amylase begins carbohydrate digestion by breaking down starch into maltose.

• Lipase helps in the digestion of lipids.

3.  Antimicrobial Action

• Lysozyme, lactoferrin, and IgA (antibodies) help inhibit bacterial growth and maintain oral microbiome balance.

• Helps prevent infections like dental caries and periodontal disease.

4.  Buffering & pH Regulation

• Bicarbonate in saliva maintains an optimal pH (6.2-7.6), preventing acid erosion and dental caries.

5.  Taste Perception

• Saliva dissolves food particles, enabling taste buds to detect flavours.

6.  Tooth Remineralization

• Calcium and phosphate in saliva help remineralise enamel, reducing the risk of cavities.

7.   Wound Healing

• Growth factors in saliva aid in tissue repair and healing of minor oral wounds.

Topic 3: Maxillary Sinus

4 pairs of sinuses (paranasal sinuses)

Functions:

• lessen the weight of skull (like cheese)

• protect the brain from frontal trauma

• offer resonance to the voice

Paranasal Sinuses:

1. frontal sinus

2. sphenoid sinus

3. ethmoid sinus

4. maxillary sinus

Topic 4: Tooth Development and Shedding

Eruption Steps Steps:

1. Pre-eruptive Phase:

   • tooth forms inside the jaw

2. Eruptive Phase:

   • tooth pushes through the bone and gum

   • root grows

   • bone reshapes

3. Post-eruptive Phase:

   • tooth settles in

   • adjusts as jaw grows and chewing wears it down

Exfoliation Steps:

1. Root resorption

   • as permanent tooth develops, it puts pressure on the root of deciduous tooth

   • cells called odontoclasts break down the dentin + cementum of deciduous tooth root (root shortens)

2. Loss of support

   • periodontal ligament weakens

   • deciduous tooth loosens

3. Final exfoliation

   • once root is completely resorbed crown of deciduous tooth falls out

Factors that impact exfoliation:

• genetics

• tooth spacing

• internal factors (ankylosis, hypodontia, etc.)

Odontoclasts:

• specialized cells that break down roots of baby teeth

• latch onto root surface and create howship’s lacunae (holes)

• release enzymes and acids to dissolve dentin + cementum

Bone remodelling:

• osteoclasts resorb alveolar bone to give space to permanent teeth

• osteoclasts deposit new bone as permanent tooth moves into position

Periodontal ligament changes:

• pdl fibres break down (makes baby tooth loose)

• pdl undergoes inflammation + apoptosis (programmed cell death)

Pulp Degeneration:

• pulp of deciduous tooth shrinks due to loss of blood supply

• fibrosis (formation of fibrous tissue) and apoptosis lead to pulp necrosis