Host Defense Mechanisms

Objectives

 List the four host defense mechanisms operational in the oral cavity.

 Describe how the epithelium functions as a microbial barrier in the mouth.

 Describe how an ideal dentition functions as a defense mechanism.

 Describe the cycle of enamel demineralization and remineralizationand assess its presence in patients.

 Evaluate caries treatment plans to include a medical model of disease prevention and nonsurgical treatment.

 Identify early and late colonizers in bacterial plaque, and discuss their roles in the disease process.

 Incorporate systemic assessments of host defense mechanisms into periodontal therapy.

 Explain the significance of plaque pH.

 Differentiate between cellular and humoral immunity.

 Describe the role of granulocytes in host defense.

 List the major salivary glands and functions of saliva.

 Prescribe appropriate therapies for a patient with compromised salivary function.

 Discuss the functions of the immunoglobulins.

 Integrate concepts of host defense mechanisms into patient treatment plans.

Four defensive systems in the oral cavity

1) anatomic barriers

2) normal oral flora

3) saliva

4) immune system

Ideal dentition is naturally resistant to infection (true/false)

true

28 teeth

Class I occlusion

Healthy interdental papillae

Epithelium

oral epithelium is always wet

typically keratinized (resistant to water)

Junctional epithelium-bottom of pocket (sulcus); lacks keratinization and is most susceptible to bacterial invasion

Three main connective tissue/lamina propria:

lining, masticatory, specialized

Which part of the oral epithelium is most susceptible to bacterial invasion

junctional epithelium

Masticatory mucosa

-keratinized stratified squamous epithelium

-on the dorsum of the tongue, hard palate and attached gingiva.

Lining mucosa

nonkeratinized stratified squamous epithelium

found almost everywhere else in the oral cavity, including the:

• Buccal mucosa- inside lining of the cheeks and floor of the mouth

• Labial mucosa-inside lining of the lips and is

• Alveolar mucosa- lining between the buccal and labial mucosae. It is a brighter red, smooth and shiny with many blood vessels, and is not connected to underlying tissue by rete pegs

Mucosal epithelium:

• Highly vascularized

• Injury to area is met with immediate blood components

• Due to this healing occurs faster

Specialized mucosa

the taste buds on lingual papillae on the dorsal surface of the tongue that contains nerve endings for general sensory reception and taste perception

Normal oral flora

not all bacteria are bad

Factors determining whether disease occurs

Bacteria varieties

Metabolic characteristics

Interrelationship of bacteria

“The most variable factor in the pathogenicity of plaque colonies is

the makeup of the microbial population.”

 some species discourage the attachment of other more pathogenic species

 some species serve as a bridge to attach pathogenic bacteria to the cells

Which bacteria are responsible for caries formation?

S. mutans

Lactobacillus

Early colonizers are

S. mitis

S. sanguis

Acquired pellicle

acellular protein layer of saliva; forms a biofilm

Streptococcus organisms

Periodontal organisms

Early and late colonizers

Goal of preventive dentistry

selective encouragement of the right mix of bacteria

Saliva’s role

 Homeostasis-ability to remain in balance and successfully resistant to challenges by chemical and bacterial agents

 Salivary flow during sleep, and during food ingestion

 The total amount of saliva secreted varies considerably between and within individuals

Saliva objectives

 List the major salivary glands and functions of saliva.

 Prescribe appropriate therapies for a patient with compromised salivary function.

 Discuss the functions of the immunoglobulins.

 Integrate concepts of host defense mechanisms into patient treatment plans.

Major salivary glands

parotid glands

submandibular glands

sublingual glands

Types of secretion

mucous and serous

Mucous

digestive and respiratory systems

protection

Serous

watery with lots of enzymes

protection

Parotid glands

 Secretes serous water fluid that contains electrolytes

 Low in organic substances

 Secretes the majority of the sodium bicarbonate

 Secretes majority of the amylase

Submandibular glands

secretes mixed serious and mucous fluid

Sublingual glands

secretes higher proportion of mucous

Minor salivary glands

 Includes the following glands:

 Palatal

 Lingual

 Buccal

 Labial

 Secrete mucous

 Lubricate surfaces for improved mastication and function

 Contribute fluoride to enhance caries resistance

(Major/minor) glands lubricate surfaces for improved mastication and function and contribute to fluoride to enhance caries resistance

minor glands

5 functions of saliva

chemical

lubrication

flushing/rinsing

antimicrobial

maintenance of supersaturation of calcium and phosphate ions

Which function is the most important in Saliva?

lubrication

Organic components of saliva

 Amylase

 Mucins

 Phosphoproteins

 Glycoproteins

 Immunoglobulins

Composition and function

Unstimulated (Always present):

 2/3 from submandibular

 ¼ parotid

 1/20 sublingual

 1/10 minor salivary glands

Moderate stimulation:

 Submandibular and parotid secrete equal

Full stimulation:

 Parotid has greatest output (1-2 mL per minute)

Functions at its best: when eating:

 Cold weather

 standing

Functions at its worst: sleeping:

 Warm weather

 sitting

Which salivary gland produces the most during unstimulated flow?

submandibular

Submandibular and parotid secrete equally during ____ stimulation

moderate

Which salivary gland secretes the most during full stimulation

parotid

Salivary flow functions at best during

eating

cold weather

standing

Salivary flow functions at its worst

sleeping

warm weather

sitting

Stimulated saliva occurs during

mastication

Unstimulated saliva occurs

when not eating