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Formation of Dental Caries Cheat Sheet by

dentistry

Tooth Decay:

Active process of tooth damage resulting from intera­ctions between bacteria, teeth and food
Primary Factors for Caries to Occur:
>Host
>Time
>Su­bstrate
>Mi­cro­-or­ganisms

Host Factors:

-Tooth
-Age
-Fluoride
-Morph­ology
-Carbo­hydrate leve
-Nutrition
Position of tooth:
- Upper>­Lower, due to salivary action
- Post>A­nte­rior, due to pits and fissures
Morp­hol­ogy:
- Teeth with stagnation area (ie. Malposed teeth, Crowded teeth)
Smooth Surfac­es:
- Interp­roximal area at contact
- Buccal at cervical third
- Lingual at cervical half

Host Factors (Part 2):

Stru­cture of Tooth:
> Pits and fissures increase propensity for caries formation
> So does depth features
Fluo­ride:
>Acts by reducing enamel solubility
> Inhibits tooth demine­ral­ization
> Enhances remine­ral­ization
Gene­tics
Age:
- 60-90% of school going children
- 100% of adults (65-75­years) have missing teeth
- As people age, caries rates and cavity severity increases
Carb­ohy­drate (CHO) level:
-Type of CHO
-Amount of CHO
-Frequency of CHO
-Local effect of CHO
-Consi­stency and refinement of CHO

Host Factors (Part 2):

Stru­cture of Tooth:
> Pits and fissures increase propensity for caries formation
> So does depth features
Fluo­ride:
>Acts by reducing enamel solubility
> Inhibits tooth demine­ral­ization
> Enhances remine­ral­ization
Gene­tics
Age:
- 60-90% of school going children
- 100% of adults (65-75­years) have missing teeth
- As people age, caries rates and cavity severity increases
Carb­ohy­drate (CHO) level:
-Type of CHO
-Amount of CHO
-Frequency of CHO
-Local effect of CHO
-Consi­stency and refinement of CHO
 

Salivary Flow:

Salivary glycop­roteins
Washing effect of saliva
Buffering effect
SIga
Antiba­cterial non-im­mun­olo­gical enzymes
CHO accumulate in poorly rinsed area

Caries Factors

Prot­ective Factors:
Path­olo­gical Factors:
-Saliva
-Bacterias
-Antim­icr­obials
-Absence of saliva
-Fluoride
-Dietary habits
-Effective diet

Bacterial Role in Caries

Germ free animals do not develop caries
Antibi­otics fed to animals are effective in reducing incidence and severity of caries
Unerupted teeth do not develop caries
Oral bacteria can demine­ralise enamel and dentin in vitro and produce caries­-like lesions
Bacteria can be isolated from carious lesions
Enamel invasion demons­trates micros­cop­ically

Charac­ter­istics of Non-Ca­rio­genic Biofilm:

Lower levels of S.mutans and lactob­acilli
Higher levels of Actio­nmyces, S.sang­uin­is,­Vei­llo­nella
Lower concen­tra­tions of lactic acid and higher concen­tra­tions of acetic and propionic acids

Charac­ter­istics of Cariogenic Bacteria:

Rate of sucrose consum­ption is higher
Rate of lactic acid formation
Synthesis more interc­ellular glycog­entype -type polysa­cch­arides
Intra- and extrac­ellular -polys­acc­harides enhance lactic acid production and coloni­sation

Aetiology of Caries

Strep­toc­occus mutans: primary agent
S.sob­rinus
Seco­ndary Invade­rs:
After initial weakening of enamel
>La­cto­bacilli
>A­cti­nom­yces

Strep­toc­occus mutans:

Faculative anaerobes
Gram positive
Does not colonize teeth uniformly
Weak ability to absorb to teeth
Low salivary concen­tra­tions available for attachment
Antago­nises growth of S.san­gui­nis:
-Acid production
-bacte­riocins

Secondary Invaders:

Divided into 2 main groups:
1. Homo­fer­men­tat­ive:
Fermen­tation of glucose produces lactic acid (eg. L.casei, L.acid­oph­ilus)
2. Hete­rof­erm­ent­ati­ve:
Fermen­tation produces lactic acids plus acetate, ethanol, carbon dioxide (eg L.fer­men­tum)
Rarely isolated in initial caries but predom­inate in deep cavities

Actino­myces:

Gram positive non-sp­oring bacillus
Microa­ero­philic
Normal microflora of the oral cavity
Acidogenic
Several species implicated but mostly: A.nae­slundi, A viscosus
 

Insoluble Glucans

Gram positive Cocci
Gram negative Cocci**
S. mutans
A.vis­cosus
S.san­guinis
A.nae­slundi
>­Caries free adults:
-Stre­pto­coccus sanguinis predom­inates over Strep.mu­tans
>High Caries adults:
-Stre­p.m­utans prevail over Strep.sa­ngu­inis

>S­tre­p.s­ang­uinis from caries free indivi­duals showed higher H2O2 production than high caries adults

Role of Strep.m­utans:

Several different species:
*S.mutans, S.sobr­inus, S.
S.mutan serotypes c,e,f and S.sob­rinus serotypes d and g are species most commonly found in humans.
>Se­rotype c most prevalant followed by d and e

Role of Strep.m­utans in Caries:

Cariogenic and initiate caries on smooth tooth surfaces
Char­act­eri­stics of S.mut­ans:
> Potent acidogenic
>Highly aciduric
>Sy­nth­esize extrac­ellular polysa­cch­arides: Glucan and Levan
> Synthesize and store interc­ellular glycog­en-like polysa­cch­arides known as amylop­ectins

Glucan vs. Levan

Gluc­an:
Levan:
Extrac­ellular polysa­cch­aride
Extrac­ellular polysa­cch­aride
Glucose polymer
Fructose Polymer
Water insoluble
Water soluble
Adhesive
Less adhesive
Glucan Binding Protein:
>S.m­utans secretes 3 distinct proteins w/glucan binding activity (GBP-A­,GBP-B and GBP-C)
>Helps in binding of glucan to S.mutans

Dext­ran­ases:
>im­portant consti­tuent of dental plaque
>enzyme produced by strp.m­utans
>de­stroy and thus bacteria can invade dextra­n-rich early plaque
>when used as an antige­n,can prevent coloni­zation of organism in early dental plaque

Glucose Degraded by Bacteria:

Embden­-My­erhof Pathway

Molecular Pathog­enesis: S.mutans

Mutans strept­ococci partic­ipate in the formation of biofilms on tooth surfaces. These biofilms are known as dental plaque(s). Sucrose is required for the accumu­lation of mutans strept­ococci. Also required for this accumu­lation are the enzymes glucos­ylt­ran­sfe­rases (GTFs), which are consti­tut­ively synthe­sized by all mutans strept­ococci.
a | Initial attachment of mutans strept­ococci to tooth surfaces. This attachment is thought to be the first event in the formation of dental plaque. The mutans strept­ococcal adhesin (known as antigen I/II) interacts with α-gala­cto­sides in the saliva­-de­rived glycop­rotein consti­tuents of the tooth pellicle. Other moieties at the surface of mutans strept­ococci include glucan­-bi­nding protein (GBP), serotype carboh­ydrate and GTFs.

Molecular Pathog­ensis: S.mutans

b | Accumu­lation of mutans strept­ococci on tooth surfaces in the presence of sucrose. In the presence of sucrose, GTFs synthesize extrac­ellular glucans from glucose (after the breakdown of sucrose into glucose and fructose), and this is thought to be the second event in the formation of dental plaque. The mutans strept­ococcal protein GBP is a recept­or-like protein that is distinct from GTFs, and it specif­ically binds glucans. GTFs themselves also have a glucan­-bi­nding domain and can therefore also function as receptors for glucans. So, mutans strept­ococci bind pre-formed glucans through GBP and GTFs, and this gives rise to aggregates of mutans strept­ococci.
 

Stages of Caries Develo­pment:

1. Enamel becomes decalc­ified
2. Small white spot appear
3. Discol­our­ation becomes pronounced
4. Tooth surface softens and decay penetrates through enamel into dentine
5. Caries spreads laterally and in depth
6. Cavitation occurs

Smooth Surface Caries:

Rarely on buccal and lingual surfaces
Mostly on approximal tooth surfaces just below contact points
S.mutans found mostly on white spots
S.sob­rinus found on caries active sites

Pit or Fissure Caries

Most caries prone sites: molars, premolars and lingual surface of maxillary incisors
S.mut­ans: -strongest associ­ation
S.sob­rinus - more frequently on molars than anterior teeth
S.sal­iva­rius, S.sang­uinis, L.acid­oph­ilus, L.casei, Actiom­yces also found
Recu­rrent Caries:
> Associated with existing restor­ation
>S. mutans and lactob­acilli

Root Surface Caries:

Seen on cementum and/or dentine when the root is exposed to oral enviro­nment
Mostly middle­-aged and older adults affected
Prevalent in primitive commun­ities
Associated bacteria: Actino­myces, Rothia dentoc­ariosa, S. mutans, lactob­acilli
Deeper caries: Propio­nib­act­erium, Bifido­bac­teria, Eubacteria
Rampant Caries:
Risk Groups:
>Xe­ros­tomic patients (S. mutans, lactob­acilli)
>“n­ursing bottle” (S. mutans, L. fermentum, L. plantarum )

Caries preven­tion:

1. Healthy Diet
2. Plaque control
3. Teeth brushing
4. Applic­ation of fluoride on tooth surfaces
5.Appl­ica­tions of sealants on tooth surfaces
Fluoride in Saliva:
Speeds up crystal precip­ita­tion, forming a fluora­pat­ite­-like coating more resistant to caries than original tooth structure

Food W/ Antica­rio­genic Effect:

Milk
Contains lactose
Cheese
Casien Phosph­atase
Fibrous Foods
Raw veg and grains
Sugar substi­tutes
xylitol, mannitol, sorbitol
Tea
green and black tea

Vitamin D

Reduces risk of cavities by producing cath­eli­cidin and denf­ens­isn.
> These proteins have antiba­cterial effects to fight bacteria that causes caries

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