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Review Chapters 13-17
Terms in this set (81)
•Stains purple as seen under a light microscope
•Single, thick multilayered mesh-like cell wall
•Composed of sugars and amino acids (peptidoglycan)
•Lies above the cytoplasmic membrane that faces interior wall of the cell
•Stains red as seen under a light microscope
•Has two membranes
•Outer membrane faces external environment
•Composed of proteins and lipopolysaccharides
•Inner membrane faces interior of the cell
•Sandwiched between two layers is a thin cell wall composed of peptidoglycan
Free-floating bacteria form biofilms quickly:
means several species of organisms are present
•Complex and dynamic microbial community containing many types of microbial species embedded within a self-protective matrix
THEY ARE EVERYWHERE IN NATURE
Living in Harmony
mutually beneficial relationship between the host and commensal microorganisms
Living is Disharmony
Five Stages of Polymicrobial Biofilm Formation
Stage 1 Initial Attachment of Microbes to Pellicle
This is the formation of film over tooth surfaces called acquired pellicle
Stage 2 Permanent Attachment
microbes begin producing substances that stimulate other free form bacteria. Coaggreration happens at this stage
Stage 3 Maturation Phase I: Self-Protective Matrix Formation
Microbes become cocooned in the protective matrix, Protects against host-generated immune defenses, Chronic disease is established
Stage 4 Maturation Phase II: Mushroom-shaped Microcolonies
Biofilm becomes thicker by stacking one microbial species on top of another forming polymicrobial colon.
Stage 5---Dispersion: Escape from the Matrix
Microbes disperse from the colony to spread and colonize other tooth surfaces
Nonspecific Plaque Hypothesis
The amount of bacteria in a biofilm adjacent to the gingival margin leads to gingival inflammation and subsequent periodontal destruction.
Specific Plaque/Microbial Shift Hypothesis
•As periodontitis develops, the oral microbiota shifts from one consisting primarily of beneficial microbes to one consisting of pathogens.
•Microbial composition of the oral biofilm (rather than the amount) is the deciding factor in the development of periodontal disease.
•An increase in the number of specific pathogens is associated with periodontitis.
•Bacteria in the biofilm change from predominantly gram-positive aerobic community to one consisting mainly of groups of gram-negative anaerobes.
Socransky's Microbial Complexes
•Grouped microorganisms into complexes and assigned each complex a color
•Orange and red complexes were thought to be the major etiologic agents of periodontal disease
•Yellow, green, blue, and purple complexes were thought to be compatible with gingival health
Problems With Specific Plaque/Microbial Shift Hypothesis
•Red complex organisms can be found in the absence of periodontal disease---are they true pathogens?
•Periodontal microbe population is more heterogeneous and diverse than previously thought
•Many newly recognized organisms have a better association with periodontal disease than those categorized in the red complex
Ecologic Plaque Hypothesis
•Accumulation of nonspecific bacteria triggers the host inflammatory response.
•Host inflammatory response alters the local environment within the gingival sulcus.
•As the local environment changes, it becomes more conducive to the growth of specific pathogenic bacteria which leads to growing specific periodontal pathogens
Microbial Homeostasis--Host Response Hypothesis
•Plaque biofilms are the cause of initial inflammatory response leading to gingivitis
•Pathogenic bacteria are not the direct cause of periodontal tissue destruction
•Host-related factors are major factors that contribute to initiation and progression of periodontal disease
•Page and Schroeder established that gingivitis does not progress to periodontitis unless another unknown factor tips the biofilm balance toward further tissue destruction
a complex body defense system that protects the body against bacteria, viruses, fungi, toxins, and parasites
The prime purpose of the immune system is to defend the life of the individual by identifying foreign substances in the body and developing a defense against them.
Prime purpose of human response system in periodontal disease
1. sending certian types of cells to the infection site
2. producing biochemical substances to counteract the foreign invaders
white blood cells that capture microorganisms on their own
small white blood cells that reorganize and control invaders
Components of the Immune System
a complex series of proteins circulating in the blood that works to
- Facilitate phagocytosis of bacteria
- Kill bacteria directly by forming pores in bacterial cell membranes
membrane attack complex
a protein unit created by the complement system that is capable of puncturing the cell membrane
•the process whereby leukocytes
Enter the connective tissue
the process by which leukocytes engulf (surround) and digest microorganisms
Inflammation is the body's protective response to pathogens, foreign bodies, or an injury
The body focuses host defense components at the site of an infection to eliminate microorganisms and heal damaged tissue.
a subgroup of cytokines—cause additional immune cells to be attracted to the site of an infection or injury.
•A short-term, normal process that protects and heals the body.
•process is achieved by the increased movement of plasma and leukocytes from the blood into the injured tissues.
Five Classic Signs of Acute Inflammation
5. Loss of function
uses cells to provide stop signals that lead to shut down and clearance of immune cells
a long-lived, out-of-control inflammatory response that continues for more than a few weeks
•condition that can destroy healthy tissue and cause more damage than the original problem.
Chronic inflammation occurs because the body is unable to rid itself of invading organism.
The invading microorganisms are persistent and stimulate an exaggerated immune response.
Signs and symptoms of chronic inflammation may partially or completely disappear during a period of
The signs and symptoms may recur in all of their severity in a active period of disease known as
are biologically active compounds secreted by cells that activate the body's inflammatory response. Important mediators include
- IL-1, IL-6, and IL-8
the host response
The way that the body responds to periodontal pathogens
The body's defenses are employed to
save the life of the host, NOT to preserve the tooth or its supporting periodontal tissues.
•all the mechanisms that enable biofilm bacteria to colonize and damage tissues
Factors Affecting Host Immune Response
is the first line of defense against microbial invasion
Chronic inflammation occurs if
the host is unable to stop recruitment of PMNs, which has pathologic effects on the host
biologically active compounds secreted by the immune cells that activate the body's inflammatory response
•Powerful mediators produced by immune cells
•Influence the behavior of other cells
•Signal to the immune system to send more phagocytes to site of infection
Functions of Cytokines
•Recruit PMNs and macrophages to infection site
•Increase vascular permeability that increases movement of immune cells into the tissues
•Can initiate tissue destruction and bone loss in chronic infections, such as periodontal disease
Prostaglandins of the E series (PGE)
initiate most of the alveolar bone destruction in periodontitis.
Overproduction of MMPs results in
breakdown of connective tissue of the periodontium.
Current Theory of Pathogenesis
•Microbial infection activates the host response
•Genetic and environmental factors modify the inflammatory response
•Mediators are produced by cells of the inflammatory response
is coordinated by interactions of osteoclasts and osteoblasts
breakdown existing bone matrix
synthesize collagen and other bone proteins
Bone Remodeling Cycle
•Resorption Phase---osteoclasts create erosion cavities in bone
•Reversal Phase---osteogenic signals stimulate osteoclasts to cease action
-Mononuclear cells adhere to erosion cavities and send signals to attract osteoblasts
•Formation Phase---osteoblasts line erosion cavity and form matrix to replace resorbed bone
•Resting Phase---interval between cessation of bone resorption and bone remodeling
Systemic risk factors
are conditions or diseases that increase an individual's susceptibility to periodontal infection by modifying or amplifying the host response to microbial infection.
Examples of Systemic Risk Factors
• Diabetes mellitus
• Metabolic Syndrome
• Hormonal variations
• Down syndrome
• Medication side effects
Three types of diabetes
•5% to 10% of type I is caused by damage to pancreas.
•90% to 95% of type II develops when the body does not make enough insulin.
•Gestational occurs during pregnancy.
•Individuals with poorly controlled diabetes are 3x more likely to develop periodontitis
•Individuals with diabetes and who smoke are 20x more likely than nondiabetics to experience severe periodontitis
Individuals with well-controlled diabetes
diabetes have no more periodontal disease than persons without
a reduction in bone mass making the woman more prone to bone fractures
•a condition in which there is a lower than average bone density but not necessarily an increase in risk or incidence of bone fracture
Closely related metabolic disturbances that occur together, increasing risk of heart disease, stroke and diabetes:
-Increased blood pressure
-High blood sugar
-Excess body fat around the waist
-Abnormal cholesterol or triglyceride levels
-Increased tendency toward thrombosis
•Characterized by abnormally few numbers of neutrophils in blood
•Leads to increased susceptibility for infection
Characteristic Facial Features of Down Syndrome
•Underdeveloped midfacial region
•Palate may appear highly vaulted and narrow due to unusual thickness of sides of palate
•Lips may be large and thick with decreased muscle tone causing drooling
•Tongue may appear cracked with fissures
•Malocclusion due to delayed eruption
•Signs in the gingiva
-Swollen, glazed, spongy tissues
-Red to deep purple in color
Gingival enlargement is occasionally seen
Drug-influenced gingival enlargement
an overgrowth of the gingiva that is a side effect associated with certain medications.
About 20 medications have the potential to enlarge the gingiva.
What are the Three major classes
Calcium channel blockers
Local contributing factors
are intraoral conditions or habits that increase an individual's susceptibility to periodontal infection or that can damage the periodontium in specific sites within the dentition
What is a Disease Site?
individual tooth or specific surfaces of a tooth that are experiencing periodontal disease
•Mineralized bacterial plaque biofilm
•Covered on external surface with nonmineralized, living bacterial plaque biofilm
•Mineralization of plaque biofilm begins from 48 hours up to 2 weeks after plaque biofilm formation
•70--90% of overall composition
•Primarily calcium phosphate with smaller portions of calcium carbonate and magnesium phosphate
•High content allows calculus to be visible on radiographs
-Not 100% accurate; lingual and facial deposits not visible
•10--30% of overall composition
•Includes materials from plaque biofilm, dead epithelial cells, dead white blood cells
•May also include living bacteria within calculus deposits
Newly formed calculus deposit
octocalcium phosphate calculus
Mature but less than 6 months old
Older than 6 months old
Treatment that results in inadvertent, adverse outcome
the space on the tooth surface occupied by the junctional epithelium and the connective tissue fibers.
Causes of Direct Damage to the Periodontium
•Improper use of plaque biofilm control aids
•Oral jewelry and body piercings
•Trauma from occlusal forces
•Parafunctional occlusal forces
Functional occlusal forces
normal forces produced during the act of chewing food
Parafunctional occlusal forces
result from tooth-to-tooth contact when not in the act of eating
Trauma from occlusion
excessive occlusal forces that cause damage to the periodontium
Signs of Trauma from Occlusion
•Sensitivity to pressure
•Migration of teeth
•Enlarged, funnel-shaped PDL space
•Alveolar bone resorption
Primary occlusal trauma
injury to the periodontium resulting from excessive occlusal forces
Secondary occlusal trauma
injury to the periodontium from normal occlusal forces applied to a periodontium previously damaged by periodontitis
Secondary occlusal trauma may result in rapid bone loss and pocket formation
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