CHAPTER 2

Periodontium: Anatomic Characteristics and Host Response

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ANATOMIC CHARACTERISTICSOF THE PERIODONTIUM

The periodontium is defined as the tissues that surround, support, and attach to the teeth.

These tissues include the gingiva, periodontal ligament, cementum, and alveolar bone.

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GINGIVA

Gingiva is described as coral pink, pink, or pale pink. Color is darker when melanin pigmentation is present.

Gingiva is distinguished from the oral mucosa at the mucogingival junction. This line indicates the transition from the loosely

attached oral mucosa to the gingiva, which is more firmly attached to the bone by collagen fibers.

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GINGIVA (CONT.)

Attached gingiva extends coronally from the mucogingival junction. Width varies from individual to individual and from tooth

to tooth. A thin band of attached gingiva is usually present in

the posterior regions. Palatal attached gingiva blends into the palatal

gingiva without demarcation.

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GINGIVA (CONT.)

Frenum and muscle attachments are present in the gingiva. Those located coronally in the attached gingiva are

associated with narrow widths of attached gingiva. Gingiva is keratinized or parakeratinized and is

commonly stippled. Nonstippled gingiva is also observed in healthy mouths.

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GINGIVA (CONT.)

Degree of keratinization varies throughout the mouth. Palatal gingiva is the most keratinized. Cheek mucosa is the least keratinized.

The tongue is covered with keratinized epithelium.

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GINGIVA (CONT.)

The edge of the gingiva next to the teeth, which is referred to as the margin, is 0.5 to 2 mm coronal to the cementoenamel junction of the teeth.

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GINGIVA (CONT.)

The free gingiva surrounds the tooth and creates a cuff or collar of gingiva that extends coronally approximately 1.5 mm.

The surface of the free gingiva next to the tooth forms the gingival wall of the sulcus.

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GINGIVA (CONT.)

The free gingiva is distinguished from the attached gingiva by a free gingival groove. This groove varies from tooth to tooth.

The free gingiva on buccal and lingual surfaces is described as knife edged.

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GINGIVA (CONT.)

The papillae, also called interdental gingivae, are gingivae that fill the embrasures. Embrasures are the proximal spaces below the contact

areas of the teeth. When the papilla is broad, often between posterior

teeth, a nonkeratinized area called the col is present. The col is not usually present between anterior teeth.

When adjacent teeth do not contact each other, the papillae and col are absent.

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GINGIVA (CONT.)

The gingival epithelium is joined to the underlying connective tissue by a basal lamina.

The fibrils join the basal lamina to the connective tissue.

The connection between the free and attached gingiva and the underlying connective tissue occurs in ridges of epithelium called rete pegs.

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EPITHELIUM

The surface tissue of the oral cavity is made up of stratified squamous epithelium. The function of the epithelium is to protect the

underlying structures. The epithelium consists mainly of keratinocytes

cells, but it also contains islets of Langerhans, Merkel cells, and melanocytes.

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EPITHELIUM (CONT.)

Keratinization occurs as the keratinocyte cells migrate from the basal layer to the surface. The cells flatten, develop keratohyalin granules, and

produce a superficial layer in which no cell nuclei are present.

When epithelium shows signs of being keratinized, but the cells retain their nuclei, the epithelium is called parakeratinized epithelium.

If no signs of keratinization are present in the epithelial surface, then the epithelium is considered nonkeratinized.

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EPITHELIUM (CONT.)

Islets of Langerhans, Merkel cells, and Melanocytes Islets of Langerhans are part of the phagocytic

system. Merkel cells contain nerve endings and are

associated with tactile sensitivity. Melanocytes are located in the basal layers of the

epithelium and contain substances that convert to melanin.

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EPITHELIUM (CONT.)

Melanin is phagocytized and remains in the cells of the epithelium, giving a pigmented appearance to the epithelium.

The following figure demonstrates an example of normal gingiva with extensive melanin pigmentation.

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ORAL OR OUTER EPITHELIUM

Oral Epithelium, also called the outer gingival epithelium, is made up of the attached gingiva, the papillae, and the outer surface of the free gingiva. The outer gingival epithelium covers the crest of the gingiva,

the free gingiva, and the attached gingiva.

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ORAL OR OUTER EPITHELIUM (CONT.)

Rete pegs project into the connective tissue below. The function of rete pegs is protective, and the

epithelium is typically parakeratinized.

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SULCULAR EPITHELIUM

Sulcular epithelium is the nonkeratinized, or parakeratinized, epithelium that extends from the outer epithelium into the gingival sulcus. Sulcular epithelium may be parakeratinized near the

opening to the oral cavity.

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SULCULAR EPITHELIUM (CONT.)

Sulcular epithelium is found from the height of the gingiva along the inner surface of the sulcus, extending to the junctional epithelium. It forms the gingival wall

of the sulcus.

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SULCULAR EPITHELIUM (CONT.)

Healthy sulcus epithelium is smooth and intact with no rete pegs projecting into the connective tissue.

Gingival crevicular fluid, which is made up of the components of the serum and other cells, is secreted through the sulcular epithelium into the sulcus.

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SULCULAR EPITHELIUM (CONT.)

A healthy sulcus is generally 1 to 3 mm deep. Measuring with a periodontal probe determines the

depth. Probe measurements are subject to variation

including: Probe insertion pressure Ability of the probe tip to penetrate tissue Accuracy of the clinician reading the probe

measurements

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SULCULAR EPITHELIUM (CONT.)

Gingival crevicular fluid, also referred to as sulcular fluid or gingival fluid, flows from the underlying connective tissue into the sulcus.

Gingival fluid: Cleanses the sulcus. Improves epithelial cell adherence to the tooth surface. Has antimicrobial and immune properties.

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JUNCTIONAL EPITHELIUM

Junctional epithelium separates the periodontal ligament from the oral environment. It is made up of nonkeratinized stratified squamous

epithelial cells that adhere to the tooth structure. Its function is to protect the attachment of the tooth to

the surrounding tissues.

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JUNCTIONAL EPITHELIUM (CONT.)

Junctional epithelium forms a layer that is 15 or 20 cells thick at the coronal end and narrowing to a few cells at the apical termination. Length in a healthy state ranges from 0.25 to

1.35 mm. Fibers from the connective tissue aid the

attachment of the junctional epithelium to the root surface. This attachment is called the dentogingival unit.

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GINGIVAL CONNECTIVE TISSUE

The connective tissue beneath the gingiva is called the lamina propria. The lamina propria is made up of two layers:

1. Papillary layer, which is beneath the epithelium• Consists of papillary projections between

the rete pegs.

2. Reticular layer, which extends to the periosteum

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GINGIVAL CONNECTIVE TISSUE (CONT.)

Approximately 60% of the lamina propria is made up of connective tissue that is composed of collagen fibrils that form fiber bundles. Other elements of the lamina propria include cells such

as fibroblasts, undifferentiated mesenchymal cells, mast cells, and macrophages, as well as blood vessels and nerves.

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GINGIVAL CONNECTIVE TISSUE (CONT.)

The fiber bundles are known as the gingival ligament.

Five principal fiber groups and six minor fiber groups make up the gingival ligament.

The gingival fiber bundles provide the most coronal connective tissue attachment for the teeth.

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PERIODONTAL LIGAMENT

The periodontal ligament provides a cushion in the space between the surface of the tooth and the bone. The periodontal ligament is a connective tissue primarily

filled with fiber bundles and cells. The cells in the ligament generate a pericementum

(periodontal membrane) on the cemental surface of the root and a periosteum (membrane) on the bone.

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PERIODONTAL LIGAMENT (CONT.)

Unusual formations of cementum, called cementicles, can also occur in the periodontal ligament. These develop from

calcified material in the periodontal ligament or from displaced bits of cementum or bone.

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PERIODONTAL LIGAMENT (CONT.)

Functions of the periodontal ligament include: Tooth anchorage Fibrous tissue development and maintenance Calcified tissue development and maintenance Nutritive and metabolite transport Sensory functions, including touch, pressure, pain, and

proprioception (displacement sensitivity)

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FIBER BUNDLES

Fiber bundles in the periodontal ligament are made up of collagen and spread throughout the periodontal ligament.

Fiber bundle functions include: Attaching the tooth to the bone Transmitting occlusal forces to the bone Resisting occlusal forces (“shock absorber”) Protecting the vessels and nerves from injury

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FIBER BUNDLES (CONT.)

The five principal fiber bundles are: Dentogingival Alveologingival Dentoperiosteal Circular Transseptal

The fiber bundles are attached to the cementum with brushlike fibers called Sharpey’s fibers.

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FIBER BUNDLES (CONT.)

Secondary gingival fiber groups include: Periostogingival Interpapillary Transgingival Intercircular Semicircular Intergingival

These fiber bundles are small collagen fibers that run in all directions in the periodontal ligament.

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PHYSIOLOGIC MESIAL MIGRATIONOR DRIFT

Physiologic mesial migration is normal tooth movement. It allows the dentition to retain balance.

The cells of the periodontal ligament mediate the changes needed in the bone and cementum to permit movement.

Gradual remodeling of the alveolar bone includes: Bone resorption by osteoclasts in response to pressure

(push) along the mesial surfaces Bone deposition by osteoblasts in areas of tension (pull)

along the distal surfaces34

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CEMENTUM

Cementum is a calcified structure that covers the root surfaces of the teeth. Cementoblasts form cementum. Cementoblasts encased in cementum are called

cementocytes. Cementum is thinner at the cementoenamel

junction and thickens as it progresses to the apex. Functions of cementum include anchoring the teeth,

maintaining occlusal relationships, and providing a seal for the dentinal tubules.

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CEMENTUM (CONT.)

Cementum contains Sharpey’s fibers. Sharpey’s fibers are the embedded portions of the fiber

bundles that attach to the roots of the teeth.

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CEMENTUM (CONT.)

Five types of cementum include: 1. Acellular afibrillar cementum with no cementocytes and no

fibers

2. Acellular extrinsic fiber cementum with no cementocytes but with bundles of Sharpey’s fibers

3. Cellular mixed stratified cementum containing intrinsic fibers and possibly cells

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CEMENTUM (CONT.)

Five types of cementum include: (Cont.)4. Cellular intrinsic fiber cementum that contains cells but no

extrinsic fibers

5. Intermediate cementum made up of cellular remnants in a calcified matrix

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CEMENTUM (CONT.)

Hydroxyapatite makes up approximately 50% of the inorganic components of cementum.

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ALVEOLAR PROCESS

The alveolar process is an extension of the bone of the body of the mandible and maxilla.

The lamina dura lines the sockets of the teeth. The socket walls may also be referred to as the

cribriform plate.

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ALVEOLAR PROCESS (CONT.)

Radiographically, the lamina dura appears as a radio-opaque line around the roots of the teeth.

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ALVEOLAR PROCESS (CONT.)

The alveolar process is composed of: Alveolar bone, which makes up the cribriform plate

encompassing the alveoli and adjacent cancellous bone Compact bone, which makes up the facial and lingual

cortical plates of bone Trabecular and cancellous bone between the cortical

plates and surrounding the alveoli

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ALVEOLAR PROCESS (CONT.)

The crest of the alveolar process follows the cementoenamel junction of the teeth. It is 2 to 3 mm apical to the cementoenamel junction

and 0.5 to 1.5 mm apical to the epithelial attachment to the tooth in the state of periodontal health.

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ALVEOLI

The alveoli are the tooth sockets. They are lined by the cribriform plate, which has

thousands of pores through which the tooth and the periodontal ligament are supplied with nerves and blood vessels.

The bone lining the alveoli contains Sharpey’s fibers.

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COMPACT BONE

Compact bone makes up the cortical plates on the facial and lingual sides of the jaws.

The alignment of the teeth, angulation of the roots to the bone, and occlusal forces determine the height and thickness of the compact bone.

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CANCELLOUS BONE

Cancellous bone lies between the cortical plates and the alveolar bone, connecting them. It is also known as spongiosum.

Less cancellous bone is found in the mandible than in the maxilla.

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VARIATIONS IN NORMAL STRUCTURE

Three variations of the normal bone structure that are nonpathologic and are of importance to periodontal health include:

1. Dehiscence Resorbed area of bone over the facial surface of the

root

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VARIATIONS IN NORMAL STRUCTURE (CONT.)

2. Fenestration An opening, or window, in

the bone covering the facial surface of a root or a boneless window between two adjacent roots that almost touch

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VARIATIONS IN NORMAL STRUCTURE (CONT.)

3. Root proximity Occurs when:

Teeth erupt with roots that are very close together.

Teeth are poorly aligned. Multirooted teeth are unusually and widely

spread out.

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ATTACHMENT APPARATUS

The periodontal ligament, cementum, and alveolar bone are referred to as the attachment apparatus.

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BLOOD SUPPLY

Branches of the inferior and superior alveolar arteries provide blood supply to the periodontium. Superior alveolar artery supplies the maxilla. Inferior alveolar artery supplies the mandible.

Branches of these vessels extend into the central alveolar bone, over the periosteum, and terminate in the periodontal ligament.

Other branches lay along the surface of the alveolar bone, terminating in capillary loops in the gingival connective tissue next to the epithelium.

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NERVE SUPPLY

Nerve supply is from the trigeminal nerve. Branches of the nerves terminate in the periodontal

ligament, the connective tissue, and on the surface of the alveolar bone.

Nerve endings receive stimuli for pain (nociceptors) and position and pressure (proprioceptors).

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CLINICAL CONDITIONOF THE PERIODONTAL TISSUES

Assessing gingival structures determines the clinical signs of health or disease of periodontal tissues.

Descriptions include the color, size, shape (or contour), texture, and consistency of the gingiva.

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COLOR

Healthy gingiva is light pink or coral pink. The vascular supply, the thickness and degree of

keratinization, and the presence of melanin produce variations in color.

The mucogingival junction should be a clearly demarcated line.

The alveolar mucosa should be bright red and shiny. It should blend without demarcation into the vestibule or

floor of the mouth.

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COLOR (CONT.)

Melanin is the product of melanocytes in the gingiva. Melanin is observed

more often in Black and Asian individuals than in people of Caucasian descent.

Melanin pigmentation is a normal variation in the color of the gingiva.

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TEXTURE

Healthy free gingiva should be smooth. Attached gingiva should be stippled, resembling an

orange peel. Stippled gingiva should have a matte appearance when

dried.

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TEXTURE (CONT.)

Stippling reflects protuberances of connective tissue into the epithelium, called rete pegs. Both stippled and nonstippled gingiva are keratinized.

Stippling varies with age. Stippling appears in children at approximately 5 years of

age, increases in adulthood, and becomes less pronounced in the older adult.

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SIZE

The presence or absence of swelling or other enlargement determines the gingival size.

Inflamed gingiva swells and appears shiny, and stippling is lost.

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SHAPE OR CONTOUR

Marginal gingiva follows a scalloped line around the crowns of the teeth and lies flat to the tooth. Is referred to as knife edged.

Papillae should fill the interdental spaces. The shape, size, and position of the teeth and the

relationship of the tooth contact areas influence the contour.

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CONSISTENCY

Consistency, or tone, of healthy attached gingiva is firm and resilient when gently touched with the back of an instrument.

Free gingiva should also be firm in texture, not soft or spongy.

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SULCUS DEPTH

Normal sulcus depth, when measured by a periodontal probe, is 1 to 3 mm.

The sulcular epithelium is intact in the healthy state, not ulcerated, and should not bleed on gentle probing.

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AGING AND THE HEALTHY PERIODONTIUM

Age-related changes that occur in the periodontium include: Thinning gingiva Decreased keratinization of the epithelium Flattening of the rete pegs More dense connective tissue Periodontal ligament with a more irregular structure Thickened cementum Alveolar bone with a less regular surface Less orderly insertion of collagen fiber

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HOST RESPONSE

The immune system is responsible for the body’s reaction, which is called the host response. Immunology is the study of the immune system and

the host response. Development of disease in the periodontium

depends on two factors:1. Microbial assault from dental plaque biofilms

2. Host response

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HOST RESPONSE (CONT.)

When microbes assault, the cells in the host form an inflammatory reaction.

Inflammation is protective in that it leads to the destruction of bacteria; however, it can also lead to tissue alteration and destruction in the host periodontal tissues. Inflammation may lead to irreversible changes in the

periodontium, which is known as periodontal disease.

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HOST RESPONSE (CONT.) The inflammatory response includes:

Inflammatory cells Antibody reactions Antigen reactions Complement reactions Hypersensitivity (allergic) reactions

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INFLAMMATORY CELLS

Inflammatory cells migrate to areas of the body when signaled by stimuli such as microbial influences. This process is called chemotaxis.

In periodontal diseases, the inflammatory cells are attracted to the gingiva, connective tissue, periodontal ligament, and bone.

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INFLAMMATORY CELLS (CONT.)

The function of the inflammatory cells is to: Ingest and neutralize bacteria, which is called

phagocytize. Secrete products that affect the permeability of blood

vessels. Cause cell disintegration, which is referred to as lysis. Cause destruction of alveolar bone by inducing

osteoclastic activity. Divide to increase their numbers in a process called

blastogenesis.

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LYMPHOCYTES

Lymphocytes recognize and react to foreign molecules. Foreign molecules are termed antigens.

Macrophages gather up antigens and present them to the lymphocytes for their destruction.

Lymphocytes retain a memory of a specific antigen and will recognize it months or years later.

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LYMPHOCYTES (CONT.)

Three types of lymphocytic cells are:1. T lymphocytes (T cells)

Are derived from the thymus. Are active in immune responses. Helper T cells assist B lymphocytes (B cells) in

the production of antibodies, which are proteins that bind and disable the antigen.

Cytotoxic T cells stimulate cytotoxic activity (cell-killing action) in other cells such as macrophages.

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LYMPHOCYTES (CONT.)

2. B lymphocytes (B cells) Are derived from the liver, spleen, and bone marrow. Serve as receptor sites for antigens. Differentiate into plasma cells, producing antibodies. Stimulate T cells to enable the immune response to

grow.

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LYMPHOCYTES (CONT.)

3. Killer or natural killer (NK) cells Antigen processing by macrophages leads to the

development of NK cells. NK cells produce antibodies and a variety of products to

stimulate the immune response. NK cells are effective against viruses and tumor cells.

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POLYMORPHONUCLEAR LEUKOCYTES

Polymorphonuclear leukocytes (PMNs), also called neutrophils, are attracted to periodontal lesions, particularly acute lesions, through chemotaxis. PMNs make up approximately 70% of the leukocytes.

PMNs phagocytize (digest) microorganisms, and they contain destructive substances that are extremely important in periodontal infections.

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POLYMORPHONUCLEAR LEUKOCYTES (CONT.)

PMNs contain granules that are filled with enzymes such as collagenase or elastase.

These enzymes are released and cause tissue destruction when the PMN cells degranulate.

Abnormalities in PMNs can lead to more severe periodontal disease if the cells are unable to perform their functions or lack specific granules.

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MAST CELLS

Mast cells mediate the inflammatory response. Their stimulation results in increased vascular

permeability, which advances the inflammatory response.

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MACROPHAGES

Macrophages are scavenger cells. They engulf and digest bacteria.

Macrophages produce enzymes and other substances that play a significant role in collagen destruction, which leads to the loss of periodontal tissues.

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AUXILIARY CELLS

Many auxiliary cells, such as basophils, eosinophils, and platelets, become involved in the immune response. They react to cytokines, which are released by the

lymphoid cells and phagocytes. Basophils contain histamine.

Histamine mediates hypersensitivity (allergic) reactions but may also enhance collagen destruction and bone resorption.

Eosinophils and platelets also produce a variety of mediating substances.

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EFFECTOR MOLECULES

The human body responds to tumor cells, bacteria, or their products by producing antibodies, which are also called immunoglobulins.

The process involves the following:1. Antigens are recognized.

2. Effector molecules are stimulated. Many effector molecules are present in the

immune system.

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ANTIBODY

Antibody production involves the following: 1. Macrophages process the antigen.

2. Macrophages then present the fragments to T cells, which interact with B cells.

3. B cells differentiate into plasma cells, which produce the antibodies.

Antibodies are found in the blood, tissue fluids such as gingival fluid, and secretions.

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ANTIBODY (CONT.)

Human (antibodies) immunoglobulins (Ig) are divided into nine distinct classes on the basis of structural differences: IgG1, IgG2, IgG3, IgG4G, IgM, IgE, IgD, IgA1, and IgA2.

The structural differences are responsible for variations in effects.

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ANTIBODY (CONT.)

Antibody responses play an important role in periodontal diseases.

The extent of the antibody response is positively related to the severity of the disease. The antibody response diminishes when the disease is

treated.

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COMPLEMENT

Complement is made up of proteins and glycoproteins whose functions include bacteriolysis (destruction of bacteria) and promotion of the immune response.

Complement reacts with IgG and IgM, causing lysis and alteration of cell walls, which encourage phagocytosis.

Complement also causes the release of histamine, increasing permeability of small blood vessels. Increased permeability permits migration of PMNs and

increased phagocytic activity in the area. The reaction can also result in destruction of periodontal

tissues.81

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CYTOKINES

Cytokines are substances produced by stimulated immune cells.

They assist in the development and regulation of immune effector cells, such as increasing the number of T cells to multiply their effects; they cause cell-to-cell communication and are, themselves, effector molecules.

Cytokines have effects on all cells of the immune system and play a major role in both the pathogenesis of disease and healing.

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CYTOKINES (CONT.)

Interleukins (IL) are cytokines that owe their names to their communication function between leukocytes. ILs are referred to by number: IL-1, IL-2, and so forth.

Other cytokines are named for their specific function, such as lymphotoxin or interferon. Interferon has antiviral properties.

Cytokines, specifically lymphotoxin, are found in large amounts in response to plaque bacteria. Lymphotoxin can stimulate bone and cartilage

resorption, leading to the destructive changes observed in periodontal diseases.

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CYTOKINES (CONT.)

A diagrammatic scheme of the interrelationships among the components of the host response in the periodontal pocket affecting the epithelium, the connective tissue, and the alveolar bone are demonstrated in the following figure.

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HYPERSENSITIVITY (ALLERGIC) REACTIONS

Hypersensitivity (allergic) reactions are responses to foreign bacteria, viruses, or other substances.

Four types of hypersensitivity reactions are: 1. Type I—anaphylactic

2. Type II—cytotoxic

3. Type III—immune complex-mediated

4. Type IV—cell-mediated (delayed)

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HYPERSENSITIVITY (ALLERGIC) REACTIONS (CONT.)

Types I, II, and III are immediate reactions and occur within minutes or hours. Types I, II, and III are the more likely hypersensitivity

reactions that affect the periodontal tissues. Type IV reactions are delayed and can occur days

later or beyond.

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ANAPHYLACTIC REACTION—TYPE I

In type I (anaphylactic) reactions, histamine is released.

The response can be generalized or localized. Generalized reaction can be life threatening (e.g., food

or drug allergies). Localized reaction can result in increased tissue

destruction (e.g., the periodontium). Histamine is found in higher concentrations in

chronically inflamed gingiva.

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CYTOTOXIC REACTION—TYPE II

In type II (cytotoxic) reactions, antibodies react directly to antigens. Type II reactions result in the breakdown of tissue or

blood cells. Cytotoxic reactions are not observed in gingival or

periodontal diseases, but these reactions may be observed in areas where antibodies react directly with epithelial cell membranes, such as in pemphigus.

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IMMUNE COMPLEX-MEDIATED (ARTHUS) REACTION—TYPE III

In type III (immune complex-mediated) (Arthus) reactions, high levels of antigen persist in an area without being eliminated.

This type of reaction occurs around small blood vessels, activates complement, and can cause extensive localized tissue damage.

An example of a type III reaction is the response observed in skin tests for tuberculosis.

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CELL-MEDIATED OR DELAYED REACTION—TYPE IV

In type IV (cell-mediated) reactions, the reaction of antigens with the surface of T lymphocytes are related to this type of hypersensitivity.

Once sensitized to an antigen, these lymphocytes can undergo blastogenesis (transformation), resulting in mitotic division and greatly increasing the number of immunocompetent (reactive) cells sensitized to the specific antigen.

These reactions explain why, on a second exposure to an allergic agent such as a beesting, the reaction can be greatly increased and possibly become life threatening. 90

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OTHER PROTECTIVE RESPONSESIN THE ORAL ENVIRONMENT

Oral epithelium acts as a barrier to mechanical and microbial assault.

The presence and amount of gingival fluid and saliva affect the interface between the surface of the tissues and the host.

Oral epithelium and saliva play a protective role in the host.

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GINGIVAL OR SULCULAR FLUID

Gingival or sulcular fluid increases with normal physiologic functions, such as mastication of foods, toothbrushing, increases in female sex hormones, and smoking, as well as after periodontal surgery.

Sulcular epithelium permits the migration of molecules into the gingival sulcus, resulting in fluid containing enzymes, cellular elements, electrolytes, and compounds such as glucose.

Leukocytes, white blood cells (primarily PMNs), make up approximately 92% of the cellular content of the fluid.

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SALIVA

Saliva provides protective influences that include: Lubrication Physical protection Cleansing Buffering Remineralization of teeth Antibacterial actions

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SALIVA (CONT.)

An increased incidence of both caries and periodontal diseases is also observed in individuals who have xerostomia (reduced salivary function).

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