Download Dental Plaque: Biofilm

Primary Preventive Dentistry
Seventh Edition
Chapter 2
Dental Plaque
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Introduction
• Dental caries and periodontal diseases are
two of the most widespread of all human
maladies, resulting from the accumulation
of many different species of bacteria
• Dental plaque is a naturally acquired, multispecies biofilm
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–1
A 13-year-old female with dental caries on the facial surface of the incisors in the maxilla
and swollen, discolored gingival tissues around the mandibular incisors, which is
characteristic of chronic gingivitis. (Courtesy of Dr. W. K. Grigsby, University of Iowa
College of Dentistry, Iowa City.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–2
The dental plaque on these teeth has been stained with a discoloring solution and rinsed.
Note the presence of plaque interproximally and adjacent to the gingiva, but relatively
absent closer to the incis. (Courtesy of Dr. W. K. Grigsby, University of Iowa College of
Dentistry, Iowa City.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Plaque: Microbial Biofilm
• Dental plaque is a multi-species biofilm
– Some bacterial species may be of greater
relevance in the development of caries and
periodontal diseases
• Historical aspect:
Most natural surfaces
have their own coating of microoganisms
or biofilm
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Historical Aspect
• One of the first known examples of life is
mineralized bacteria or algae attached to
rocks from the Precambrian Era
(approximately 3800 million years ago)
• Calculus is a hard calcified deposit of
plaque that has become mineralized
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Plaque: Biofilm
• Not all microorganisms within the biofilm
population react uniformly to antimicrobial
treatment at a given time
• It is important to include mechanical oral
hygiene practices in addition to using
antimicrobial therapy to disturb the
attached biofilm
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Bacterial Colonization of the Mouth
• Bacteria are acquired from:
– Atmosphere
– Food
– Human contact
– Contact from animals, such as pets
• Bacteria subsequently form colonies
between saliva and oral soft and hard
tissues
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Tooth Eruption
• Prior to eruption the external surface of
tooth enamel is lined by remnants of the
enamel-forming organ
• These tissue remnants are the reduced
enamel epithelium and the basal lamina
• This subsurface organic material is called
subsurface pellicle
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–3
This transmission electron micrograph demonstrates remnants of the subsurface pellicle
(SSP) and the acquired pellicle (AP) between the enamel (ES) surface and the
bacterial cells (B) of the dental plaque. (Courtesy of Dr. M. A. Listgarten, University of
Pennsylvania School of Dental Medicine, Philadelphia.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–4
Junction of reduced enamel epithelium and enamel. The reduced ameloblasts (RA) are
attached to the enamel by hemidesmosomes (HD) and a basal lamina (BL). EM,
enamel matrix remnants form a subsurface pellicle; ES, enamel space. Original
magnification × 45,000. (Courtesy of Dr. M. A Listgarten, University of Pennsylvania
School of Dental Medicine, Philadelphia.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Tooth Eruption (Continued)
• An erupted tooth immediately becomes
covered by a thin, microscopic coating of
saliva materials
• It is acquired after tooth eruption and is
exogenous in nature
• Referred to as acquired pellicle
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
The Acquired Pellicle
• Acellular
• Consists primarily of glycoproteins derived
•
•
from saliva
Occupies million of microscopic voids in
the erupted tooth caused by chemical and
mechanical interactions of the tooth
surface with the oral environment
If the pellicle is displaced by a prophylaxis
it begins to reform immediately
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
The Acquired Pellicle (Continued)
• Also forms on dental restorations
• Interestingly, there is competition for
binding sites on the pellicles, not only by
receptors on bacteria but also from host
proteins, including immunoglobulins
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Plaque Formation
• Mechanical displacement
• Stagnation
• Availability of nutrients
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–5
Scanning electron micrograph of dome formation in the plaque.
(From Brady, J. M. (1973). J Periodontol, 44:416–28.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Molecular Mechanisms of Bacterial
Adhesion
• The initial bacterial attachment to the
acquired pellicile is thought to involve
physicochemical interactions between
molecules or portions of molecules
• Bacteria have external cell-surface
proteins termed adhesions
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–6
This diagram illustrates some of the possible molecular mechanisms that mediate attachment of bacteria to
teeth during dental plaque formation. A. A side chain of a phenylalanine component of a bacterial protein
interacts via hydrophobic bonding with a side chain of a leucine component of a salivary glycoprotein in
the acquired pellicle. B. The negatively charged carboxyl group of a bacterial protein is attracted to a
positively charged calcium ion (i.e., electrostatic attraction), which in turn is attracted to a negatively
charged phosphate group of a salivary phosphoprotein in the acquired pellicle. C. The host’s dietary
sucrose is converted by the bacterial enzyme, glucosyltransferase, to the extracellular polysaccharide,
glucan, which has many hydrophobic groups and can interact with amino acid side-chain groups, such as
serine, tyrosine, and threonine. D. The fimbrial surface appendage extends from the bacterial cell to
permit the terminal adhesin portion to bind to a sugar component of a salivary glycoprotein in the
acquired pellicle.
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Bacteria in the Dental Plaque
• Supragingival
• Subgingival
• Primary colonizers
• Secondary colonizers
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Plaque Matrix
• Dental plaque consists of different species
of bacteria that are not uniformly distributed
• The bacterial cells in the biofilm are
surrounded by an intercellular plaque
matrix which is composed of both organic
and inorganic components
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–7
An electron micrograph showing palisades (P) of bacteria perpendicular to the enamel
surface (ES), bacterial cells that are probably secondary colonizers (SC), the
intercellular plaque matrix (IPM), and the acquired pellicle (AP). (Courtesy of Dr. M. A
Listgarten, University of Pennsylvania School of Dental Medicine, Philadelphia.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–8
A. Cross section of “corn cob” from 2-month-old plaque. A coarse fibrillar material
attaches the cocci (C) to the central filament (CF). Original magnification × 22,500. (From
Listgarten, M. A., Mayo, H. E., & Tremblay, R. (1975). J Periodontol, 46:10–26.)
B. Coarse “test-tube brush” formations consisting of central filament (CF) surrounded by
large, filamentous bacteria with flagella uniformly distributed over its body (LF).
Background consists of a spirochete-rich microbiota (S). Original magnification × 4,300.
(From Listgarten, M. A. (1976). J Periodontol, 47: 1–18.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Plaque Metabolism
• A source of energy is required for
metabolism to occur
• Once exposed to sucrose, microorganisms
produce:
–Acid
–Intracellular polysaccharides
–Extracellular polysaccharides
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Calculus
• The term calculus is derived from the Latin
word meaning pebble or stone
• Calculus itself is not harmful and cannot be
removed by brushing or flossing
• It needs to be removed because its
presence makes routine oral hygiene
difficult
• May be affected by behavioral factors and
systemic conditions
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–9
Radiograph demonstrating a “spur”- shaped deposit of calculus (C) on the distal side of
the left first molar in the maxilla. The calculus is apical to the overhanging metallic
restoration (R). The arrow (G) marks the coronal level of the gingival tissues, which
indicates that this is a subgingival deposit of calculus. (Courtesy of Dr. W. K. Grigsby,
University of Iowa College of Dentistry, Iowa City.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Calculus (Continued)
• Crystals in calculus include:
– Hydroxyapatite
– Brushits
– Whitlockite
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–10
Deposits of supragingival calculus on the lingual surface of incisors and canines that
could not be removed by brushing. (Courtesy of Dr. W. K. Grigsby, University of Iowa
College of Dentistry, Iowa City.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Calculus (Continued)
• The two types of calculus may differ in
color:
– Supragingival calculus usually appears as a
yellow to white mass with a chalky consistency
– Subgingical calculus appears gray to black in
color and has a flint-like consistency
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–11
Typical pattern of dental plaque mineralization in which the initial mineralization occurs in
the inter-bacterial plaque matrix (M), with bacterial cells (B) becoming mineralized
secondarily. Original magnification × 40,000. (Courtesy of Dr. M. A. Listgarten,
University of Pennsylvania School of Dental Medicine, Philadelphia.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
FIGURE 2–12
Atypical pattern of dental plaque mineralization in which bacterial cells (B) act as foci of
initial mineralization, with the matrix (NM), becoming mineralized secondarily. Original
magnification × 25,000. (Courtesy of Dr. M. A. Listgarten, University of Pennsylvania
School of Dental Medicine, Philadelphia.)
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Dental Calculus (Continued)
• Attachment of calculus to the teeth
• Inhibition of calculus formation
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Summary
• Microbial film
• Bacterial colonization
• Acquired pellicle
• Dental plaque formation
• Molecular mechanisms
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Summary (Continued)
• Bacteria in the dental plaque
• Dental plaque matrix
• Dental plaque metabolism
• Dental calculus
Primary Preventive Dentistry, Seventh Edition
Norman O. Harris, Franklin García-Godoy, and Christine N. Nathe
Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.