Chapter 17 Flashcards
a community of microorganisms in micro colonies that grows on surfaces within the mouth, which is a primary risk factor for gingivitis, inflammatory periodontal diseases, and dental caries.
Dental biofilm
During clinical examination of the teeth and surrounding soft tissues, soft and hard deposits are assessed. The presence of dental biofilm is a primary risk factor for
gingivitis, inflammatory periodontal diseases, and dental caries.
What deposits are considered soft deposits?
acquired pellicle
dental biofilm
materia alba
food debris.
What is acquired pellicle?
a thin, acellular, tenacious film formed of proteins, carbohydrates and lipids uniquely positioned at the interface between the tooth surfaces and the oral environment. It forms over exposed enamel, dentin, mucosa, and restorative materials.
What are the types of Acquired Pellicle?
Acquired enamel pellicle and acquired dentin pellicle
What are the functions of pellicle?
- Regulation of mineral homeostasis as the pellicle structure may serve as a scaffold for remineralization so it protects against acid-induced enamel demineralization and erosion.
- Host defense and microbial colonization
About 8% of the proteins in the pellicle have antimicrobial functions. - Lubrication: Pellicle keeps surfaces moist and prevents drying, which in turn enhances the efficiency of speech and mastication.
How can a pellicle be removed?
At home, oral self-care regimen can easily remove and interfere with pellicle formation. Intake of acidic foods and drinks can also interfere with formation of
What is an oral microbiome?
The complex community of microbes composed of bacteria, fungi and so on and their genetic makeup inhabiting the different environments in the oral cavity
the only nonshedding surface in the body that serves as a unique environment for biofilm formation and maturation.
The permanent teeth
Dental biofilm is a
dynamic, structured community of microorganisms, encapsulated in a self-produced extracellular polymeric substance (EPS) forming a matrix around microcolonies.
____ Adheres to the pellicle coating on all hard and soft oral structures, including teeth, existing calculus, and fixed and removable restorations.
Dental biofilm
The potential for the development of dental caries and/or gingivitis increases with _______in dental biofilm
more pathogenic microorganisms
In the distribution of oral biofilm, what are the locations of biofilm?
• Supragingival biofilm: Coronal to the gingival margin.
• Gingival biofilm: Forms on the external surfaces of the oral epithelium and attached gingiva.
• Subgingival biofilm: Located between the epithelial attachment and the gingival margin, within the sulcus or pocket.
• Fissure biofilm: Develops in pits and fissures of the teeth.
What are the factors that may increase accumulation of biofilm?
crowded teeth
Rough surfaces
Malocclusion
Removal of Biofilm
____are the most universal daily mechanical disruption methods.
Toothbrushing and interdental cleaning
What can be used for detection of oral biofilm?
A. Direct Vision
B. Use of Explorer or Probe
C. Use of Disclosing Agent
D. Clinical Record
Biofilm plays a major role in the initiation and progression of___, caused by____
dental caries and periodontal diseases; pathogenic microorganisms found in oral biofilms.
Biofilm is significant in the formation of dental calculus, which is essentially
mineralized dental biofilm.
Dental caries is a disease of the
dental calcified structures (enamel, dentin, and cementum) characterized by demineralization of the mineral components and dissolution of the organic matrix.
The sequence of events leading to demineralization and dental caries is
Cariogenic foodstuff leads to fermentable carbohydrates taken into biofilm
Ph of biofilm drops as the bacteria consume the carbohydrates
Acid is formed
Frequent exposure of tooth surface to acid leads to demineralization
Demineralization appears as a white lesion and is the start of caries
Eventually cavitated lesion develops
Describe the microbiome of when a patient presents with caries
reduced diversity of microorganisms in microbiome to favor caries initiation.
Acid tolerant or acidogenic bacteria like S. mutans and S. sobrinus, and lactobacilli may be present. Possibly in some cases Actinomyces
Explain the ph of biofilm
Critical pH for enamel demineralization averages 5.5.
The critical pH for root surface demineralization may be higher because of the lower mineral content of dentin and cementum.
The critical pH for demineralization of dentin is approximately 6.7, which is particularly relevant for patients with multiple areas of recession and xerostomia.
What are the effects of diet on biofilm?
In a diet high in fermentable carbohydrates and cariogenic foods, biofilm
communities shift to bacteria with higher pH-lowering ability.
What is materia alba?
a soft, whitish tooth deposit that is unorganized accumulation of living and dead bacteria, desquamated epithelial cells, disintegrating leukocytes, salivary proteins, and food debris. It is clinically visible without application of a disclosing agent. It may have a cottage cheese-like texture and appearance.
Prevention of Materia alba
can be removed with the basic mechanical oral self-care
procedures.
After food consumption, food remnants may collect in areas of the cervical third and proximal embrasures of the teeth.
Food Debris
____ results during mastication as food is forced into open contact areas (loss of proximal contact), dental diastemas, poorly contoured restorations, or occlusal irregularities such as plunger cusps.
Vertical food impaction
Left unattended, the accumulation of ____adds to a general unsanitary condition of the mouth and may contribute to the initiation of dental caries and oral malodor.
food debris
Dental calculus is
dental biofilm mineralized by crystals of calcium phosphate mineral salts between previously living microorganisms that forms on the clinical crowns of natural teeth, dental implants, dentures, and other dental prostheses.
Calculus is covered with a layer of____
nonmineralized dental biofilm containing live bacteria
Dental calculus is classified by its location on a tooth surface as related to the adjacent free gingival margin, that is_______
supragingival and subgingival calculus
This type of calculus forms on clinical crowns coronal to the margin of the gingiva, implants, complete and partial dentures.
Supragingival calculus
Where are the most frequent sites of supragingival calculus?
On the lingual surfaces of mandibular anterior teeth and the facial surfaces of maxillary first and second molars
On the crowns of teeth out of occlusion, nonfunctioning teeth, or teeth that are neglected during daily biofilm removal (toothbrushing or interdental care).
On surfaces of dentures, dental prostheses, and oral piercings.
Calculus that forms apical to the margin of the gingiva and extending toward the clinical attachment on the root surface.
Forms on dental implants.
Subgingival calculus
Where are the most frequent sights of subgingival calculus?
The calculus typically will form at the cementoenamel junction as recession and pocket formation continue. May be generalized or localized and heaviest in areas most difficult for the patient to access during personal oral biofilm removal procedures.
The color of subgingival calculus comes from exposure to the
products of blood, blood breakdown products and also bacteria formed in calculus can contribute to the pigment
Calculus is composed of
inorganic and organic components and water.
How does calculus form?
Dead microorganisms breakdown and the initial calcium phosphate crystals (typically brushite) of calculus start to form by binding with the phospholipids in the cell walls (cell membrane) of bacteria. Eventually mineralization of calculus will progress to include the other types of calcium phosphate crystals octacalcium phosphate, whitlockite, and finally to a stable hydroxyapatite phase that occurs around 8 months after initial formation.
What are the factors in rate of calculus formation?
Genetic and individual variation in saliva composition and flow.
Diet
Individual variations in bacterial load.
Age, race, and gender.
More severe periodontal disease.
Malposition and crowding of teeth.
Lower levels of S. mutans.
Presence of inhibitors of calculus formation
Types of Calculus Deposits
• Crusty, spiny, or nodular deposits.
• Ledge or ring formation.
• Thin, smooth veneers.
• Finger- and fern-like formations.
• Individual calculus islands or spots.
How does calculus attach to a tooth?
1.by Means of an Acquired Pellicle
- to Minute Irregularities in the Tooth Surface
- by Direct Contact with the Tooth Surface
by interlocking of inorganic apatite crystals of the enamel and cementum with the calcium phosphate crystals of the calculus.
The extent of demineralization of a tooth depends on what factors?
the length of time and frequency the pH is below critical level, biofilm composition, pH-lowering ability of the microorganisms, and action of saliva
Dental calculus contains what four types of calcium phosphate crystals?
• Brushite
• Octocalcium phosphate
• Hydroxyapatitie
• Whitlockite
The formation time of calculus depends on
individual factors like homecare
What is the color of supragingival calculus?
White, creamy yellow, or gray. May be stained by tobacco, food, tea, or coffee
Slight deposits may be invisible until dried with compressed air
What is the color of subgingival calculus?
Light to dark brown, dark green, or black due to gingival crevicular fluid, blood and blood breakdown products
What is the shape of supragingival calculus?
Amorphous, bulky
Gross deposits may:
• Form interproximal bridge between adjacent teeth.
• Extend over the margin of the gingiva
• Form based on the anatomy of the teeth; contour of gingival margin; and pressure of the tongue, lips, cheeks
What is the shape of subgingival calculus?
Conforms to the root surface due to constraints of the pocket wall
Calculus formations occur in the following forms:
• Crusty, spiny, or nodular
• Ledge or ringlike
• Thin, smooth veneers
• Finger- and fern-like
• Individual calculus islands
What is the distribution of calculus on an individual tooth supragingivally?
Coronal to margin of gingiva
What is the distribution of calculus on an individual tooth subgingivally?
Apical to margin of gingiva
Extends to bottom of the pocket and follows contour of soft-tissue attachment
What is the distribution of calculus on
teeth supragingivally?
Symmetrical arrangement on teeth, except when influenced by:
• Malpositioned teeth
• Unilateral hypofunction
• Inconsistent personal oral self-care
Location related to openings of the salivary gland ducts
What is the distribution of calculus on
teeth subgingivally?
Heaviest on proximal surfaces, lightest on facial surfaces
Occurs with or without associated supragingival deposits
How do we do a supragingival examination for calculus?
A. Direct Examination (use mouth mirror for indirect)
B. Use of Compressed Air and light for invisible deposits
How do we do a subgingival examination for calculus?
A. Visual Examination: (Dark edges of calculus may be seen at or just beneath the gingival margin.
B. Gingival Tissue Color Change for dark calculus
C. Tactile Examination
D. Radiographic Examination
E. The use of a dental endoscope
Risk factors related to calculus formation are similar to those for dental biofilm formation and relate to the patient’s___
daily biofilm removal regime