Caries Flashcards
Bacterial components of dental plaque cause dental caries:
in particular Strep. mutans, Strep sobrinus, and lactobacilli0-pp
Mutacin
antibiotic peptide produced by Strep. Mutans. Class of compounds called lantibiotics
Definition of caries
refers to the dissolution of tooth enamel and dentin. It starts in the pits, fissure, and interdentinalregions of the teeth, “stagnation areas” from which bacteria are difficult to remove. The extent of caries is measured as the number of teeth diagnosed as decayed, missing, or filled due to caries-DMFT (Levine)
Refined sugar
pure sucrose
Unrefined sugar
unprocessed sweeteners, e.g., honey, agave nectar, molasses, raw sugar, maple syrup, palm sugar
Hydroxyapatite
naturally occurring mineral form of calcium phosphate {Ca5(PO4)3(OH) or stoichiometricCa10(PO4)6(OH)2}. One hydroxyl group can be substituted by carbonate, fluoride, or chloride. Hydroxyapatite is the form of mineral which is found in bone and teeth
Fluoroapatite
hydroxyapatite with a hydroxyl group substituted by fluoride atom. Because fluoride is more electronegative than hydroxyl group, it replaces the latter in the hydroxyapatite crystal structure without altering the overall structure, called an isomorphousreplacement
Secondary dentin
formed after tooth formed as a layer on the root bordering pulp tissue
Tertiary dentin
created in response to stimulus like caries or wear
Biofilm
a group of microorganisms in which cells stick to each other on a surface. Adherent cells may be embedded within a self-produced matrix of polymeric extracellular substance or slime which also includes DNA, proteins and polysaccharides. Cells within a biofilm can exhibit special phenotypic and symbiotic characteristics
Fluorosis
developmental problem also termed mottling of teeth which is caused by exposure to excessive concentrations of fluoride (>1ppm)
Remineralization
the delivery of calcium and phosphate, from outside the tooth, into the enamel lesion, the presence of fluoride favors deposition of mineral onto the demineralized enamel surface
Endocarditis
typically occurs when bacteria from another part of your body, such as your mouth, spread through your bloodstream and attach to damaged areas in your heart. Left untreated, endocarditis can damage or destroy your heart valves and can lead to life-threatening complications. Treatments for endocarditis include antibiotics and, in severe cases, surgery
Endocarditis is uncommon in people with healthy hearts. People at greatest risk of endocarditis have a damaged heart valve, an artificial heart valve or other heart defects.
Dental Abscess
region of pus within teeth or gums usually initiated as a bacterial infection
Asaccharolyticbacteria
do not metabolize glucose for energy source but use protein and amino acids instead. These bacteria contribute to the ability of advanced caries to degrade dentin collagen matrix and expand the cavity
what are caries
infectious disease
multifactorial aspects of caries (7)
biofilm bacteria time diet habits education socioeconomic factors
AAPD Policy Statement 1
Avoiding frequent consumption of liquids and/or solid foods containing sugar, in particular:
• Sugar-sweetened beverages (e.g., juices, soft drinks, sports drinks, sweetened tea) in a baby bottle or no-spill training cup.
• Ad libitum breast-feeding after the first primary tooth begins to erupt and other dietary carbohydrates are introduced.
• Baby bottle use after 12-18 months.
• Caries-conducive dietary practices appear to be established by 12 months of age and are maintained throughout early childhood
• Fruit juice should be limited to no more than 4-6 oz. per day for children one to six years old
AAPD Policy Statement 2
- Implementing oral hygiene measures no later than the time of eruption of the first primary tooth. Tooth brushing should be performed for children by a parent twice daily, using a soft toothbrush of age-appropriate size.
- In children under the age of three, a smear or rice-sized amount of fluoridated toothpaste should be used. In children ages three to six, a pea-sized amount of fluoridated toothpaste should be used.
AAPD Policy Statement 3
Providing professionally-applied fluoride varnish treatments for children at risk for ECC.
AAPD Policy Statement 4
- Establishing a dental home within six months of eruption of the first tooth and no later than 12 months of age to conduct a caries risk assessment and provide parental education including anticipatory guidance for prevention of oral diseases.
- Preventive interventions within the first year of life are critical
AAPD Policy Statement 5
• Working with medical providers to ensure all infants and toddlers have access to dental screenings, counseling, and preventive procedures.
AAPD Policy Statement 6
• Educating legislators, policy makers, and third partypayorsregarding the consequences of and preventive strategies for ECC.
dental caries
decay and crumbling of tooth
bacteria in dental plaque eat — from our diet
carbohydrates
bacteria secrete
acids
acids lower
oral pH
enamel demineralizes at pH of
5.5 or below
enamel demineralization results in
carious lesions
location of caries (2)
pit and tissue
smooth surface
new lesion
attacking a previous intact surface
recurrent lesion
occurs around margins of restoration
residual caries
caries left behind before a filling is placed
visualization of caries
clinical: dark shading under enamel
radiographs
tactile diagnosis of caries
no longer the primary method of caries detection
may gently run tip of explorer over area of tooth (leathery feel nay denote caries)
ADA caries classification system
initial caries
moderate caries
severe caries
caries is a — disease (3)
infectious
manageable
preventable
primary microbes in bacterial disease
strep mutans, lactobacillus, actinomyces
requirements for caries (4)
susceptible host
bacteria
food source
time
major difference in dental caries in two populations of American Indians who lived near each other but were either hunter gatherers or with devoted to agriculture. Much higher incidence of caries associated with the
high carbohydrate diet (agricultural) versus high protein diet of the hunter gatherers
remineralization
- Saliva rinses away carbohydrates, buffers acids
- Minerals in saliva (calcium, phosphate) re-enter tooth
- Good oral hygiene
- destroys biofilm so bacteria can’t attach
A carious lesion (cavity) occurs when
demineralization is greater than remineralization over time
saliva functions (4)
- Raises pH to non-demineralizing levels
- Flushes away floating microbes
- Antibacterial properties
- Calcium and phosphate ions to enter tooth
home care
- Removes bacterial habitat
* Bacteria can’t stick= bacteria can’t causedemineralization
diet
- Avoid frequent sugar consumption (Strep mutans’ favorite!)
* “starve” bacteria
fluoride
- Makes teeth less susceptible to acid
* “stronger” enamel
common concerns of fluoride (3)
- Lowers IQ
- Poison added to water supply
- Fluorosis
enamel (5)
- Outerlayer
- 96% calcium hydroxyapatite crystals
- 4% organic materials and water
- Enamel is the most highly mineralized tissue in the body
- Amelogenesis (enamel formation) ends at tooth eruption, there is no secondary or post-natal production of enamel
dentin (4)
- 45% hydroxyapatite crystals
- 33% organicmaterial(collagen, etc)
- 22% water
- Dentin can be produced post-natallyas when secondary dentin or tertiary dentin is formed
dental enamel junction (DEJ)
Formed during development, the DEJ is a product of odontoblasts and ameloblastsand it bridges these two dissimilar mineral phases.
how does the DEJ act as a barrier?
- must be penetrated in order fordecay to progress to the dentin and ultimately to the pulpal chamber.
- Decay process for dissolution of enamel primarily requires acid to dissolve the mineral hydroxyapatite. In contrast, dissolution of the dentin requires both specific collagenase and likely other proteases to breakdown collagenous matrix and alsoacid to dissolve the mineral crystals present.
Ameloblasts form individual enamel rods via their
Tome’s processes
Mutansstreptococci participate in formation of
biofilms on tooth surfaces
PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake which uses
phosphoenolpyruvate as an energy and phosphate source
It is a multicomponent system that always involves enzymes of the
plasma membrane and those in the cytoplasm
The phosphotransferase system is involved in transporting many sugars into bacteria, including (5)
glucose, mannose, maltose, fructose and cellobiose
PTS sugars can differ between bacterial groups, mirroring the
most suitable carbon sources available in the environment every group evolved
fructose as a source of bacterial lactic acid
sucrose s transported as fructose-6-phosphate where it is phosphorylated to fructose-1,6-bisphosphate and metabolized to lactic acid by glycolysis. Lactic acid is excreted but trapped at the tooth surface by the glucancapsule.
salivary amylase as a source of bacterial lactic acid
attaches bacteria to teeth surfaces. Following a carbohydrate-rich meal, amylase digests these carbohydrates (starches) to maltose, which is transported into the cytosol similar tofructose-6-P. Within the bacteria, maltose is digested into to two molecules of glucose-6-phosphate and then metabolized to lactic acid.
other bacteria as a source of bacterial lactic acid
besides Strep. mutanscan contribute to the production of lactic acid. Actinomycesspp. and viridansspecies of streptococci are common in the oral cavity and can bind to teeth surfaces via salivary proteins in the absence of sucrose. Can make glucansand fructanswhich enhance adherence of Strep. mutansand acid production. S. mutansmakes glucanbinding proteins which facilitate adherence to these other bacterial glucansand help stabilize the capsule
Structure of mutansis resistant to digestion with bacterial enzymes (2)
dextranase and fructanase
development during advanced caries
- As the region becomes more acidic, the developing cavity promotes greater colonization by S. mutans and even more acid resistant bacteria, e.g., Lactobacillus ssp.
- The latter expand the cavity deeper into dentin.
- Asaccharolyticbacteria of the oral microbiota induce inflammation and abcesseswithin the pulp and periapical regions of a tooth affected with untreated late stagedental caries.
Production of bicarbonate from carbon dioxide is catalyzed by — — enzyme which is present in saliva and salivary glands
carbonic anhydrase
Saliva flow over the teeth and its bicarbonate content are a major resistance towards
caries
The — and — of teeth also affect saliva access and thus indirectly affect development of caries, e.g., orthodontic treatment.
shape and spacing
Dr. McKay and Deans findings
- Studies by Frederick Summer McKay led to identification of fluoride as cause of fluorosis (mottled teeth)
- McKay outlined the geographic boundaries of areas where mottled enamel was found , determined the % of afflicted individuals and compiled evidence that pointed to water supply as a cause.
- Further work led to identification of fluoride as agent associated with mottled teeth•Dr. Dean advanced McKay’s findings
- Subsequent larger studies showed an inverse relationship between tooth decay and ingestion of fluoride
- Decay increased also when water supplies were changed to unfluoridatedsources.
Fluoride may become ineffective below a pH of
4.5
Analysis of clinical and mechanistic data suggests that topically applied fluoride is more effective at preventing the
establishment of early lesions than their progression
fluoride protection against caries has identified three mechanisms by which it operates (3)
- Inhibition of demineralization
- Enhancement of remineralization
- Inhibition of bacterial enolase activity inhibiting lactase production from ingested carbohydrates
The mineral phase of bones and teeth is
carbonated hydroxylapatite
Dentin and enamel are composite materials of
collagen and mineral
Hydoxyapatiteis soluble in acid, e.g., at pH values less than
5.5
Severity of caries is related to the pH produced in dental biofilms (plaques) after
ingestion of sucrose and other sugars
Caries related to consumption of high carbohydrate diet which are metabolized by plaque, generating lactic acid due to fermentation which
demineralizes enamel and exposes underlying dentin
Prevalence of dental caries greatly increased with introduction diets high in
processed sugar
dental carries occur in areas of the tooth, crevices and regions of limited
salivary flow, which favor formation of a biofilm
Biofilms are resistant to destruction, particularly
mutans polysaccharide
Biofilms facilitate sequestered spaces which retain acids secreted by bacteria, which results in
demineralization of enamel hydroxyapatite of teeth
advanced caries leads to
destruction of the dentin by protein metabolizing bacteria
Fluoride is an excellent therapeutic treatment for prevention of
caries
— and its bicarbonate component play an important preventive role against caries
Saliva
