Caries PDF

ESSAM GABALLAH CARIES 1 Epidemiology 90% of schoolchildren worldwide and most adults have experienced caries, with the disease being most prevalent n Asian and Latin American countries and least...

ESSAM GABALLAH CARIES 1 Epidemiology 90% of schoolchildren worldwide and most adults have experienced caries, with the disease being most prevalent n Asian and Latin American countries and least prevalent African countries. the United States, dental caries is the most n common chronic childhood disease CC Scroll for details D 1:51 / 39:57  hygiene practIces and preventive measures such as fluoride treatmnent. Some countries, such as Australia, Nepal, and Sweden,have a low incidence of cases of dental caries among children, whereas cases are more numerous in Costa Rica and Slovakia. DOLL  Definition Microbical disease of thetooth characterized by destruction of hardtooth substance Chroug demineralization ofthe inorganic part of the tooth and dissolution of the organic part of the tooth by the action of bacteria unhealing irreversible affect all races in teeth bearing age (from months till Extraction) LAH CARIES 1 ELIOIOgy Acidogenic theory (Miller'schemíco-parasitic theory). Proteolytictheory Proteolysis chelation theory ABALLAH CARIES1 Acidogenic theory I- 1ry stage: Micro organisms+ + acids which cause carbohydrates demineralization of enamel II- 2rystage: Dissolution of the organic part of the tooth  According to acidogenic theory caries Drocess isaffected by three factors: Carbohydrates Micro-organisms. Acids. Carbohydrates 1-mechanism of 2- type 3- Factors action Polysaccharides Easily fermented by plaque bacteria Physical fom Disaccharide Glucosyl transferase Frequency mono saccharides extracellular glucans (dextran). Chenical form lactic acid Easily converted into intracellular storage, polysaccharides (ISP Foute Decalcification Food compag  b- Role ofmicro-organisms: About 22 type of bacteria were isolated from the carious teeth Produce acid (acidigenic). Produce ISP (glycogen). Produce extracellular glucans (dextran). Can live in acid (acidophilic). start of caries e.g strept. Mutans progress of caries e.g lactobacilli  NRole of acids: Lactica Butyric a Byruvic a Acids produced in the oral cavity are neutralized and diluted with salivary bufferes ,thusto be effective in caries production it must be: a- protected from salivary bufferes. b-localized on Tooth surface  This is done by the dental plaque (bacterial plaque) Def Gelatinous insoluble colorless transparent membrane which is semipermeable adherent to the tooth surface Eotituents ofdental plaque 1- Microorganisms: a- Fillamentous type forming a network. b- Streptococci which fill the meshes of the network done by filamentous bacteria.  2-The microorganismsare suspended in opoumatrix derived from: a- salivary glycoproteins from saliva. b- extracellular glucans formed by bacteria (dextran). 3- Desquamated epithelial cellis 4- Mucin from saliva. 5- Food depris and carbohydrates, lipids. 6- Inorganic components Ca, Ph, Mg, Na, fluoride.  Formation of dental plaque: Withinseconds after meal the enamel surface becomes covered with a layer of salivary Glycoproteins (called pellicle) which can be removed. Within 2 hours. bacteria are adsorbed on the pellicle After 24-48 hours Cannot be removed because of bacteria sticked with dextran plaque.  Mechanism of action of dental plaques 1. The PH of the plaque may or according to the oral environments (i.e sugar intake PH and vice versa). 2.At critical PH (about 5.5) mineral ions are libarated from the layer of superficial hydroxy appetite crystals and diffuse into the plaque. > then from plaque to saliva this process is repeated demineralization. (so chate bet. Meals is important to carie Around neutral PH the plaque is supersaturated with mineral ions,some of which may rediposite on the enamel suface again (remineralization). Bacteria inthe plaque store chate as "intracellulcar glycogen like polysaccharides" (1SP intracellulcar storapolysaccharides) (amnylopectin). when chates are abscent from the mouth these ISP. Are utilized by bacteria to produce acids. Also bacteria the plaque can synthesize extracellular in glucans from dietary sugers (by glucosyle-transferase enz.). The extracellular glucans (dextran)is important in  It is able to adhereto the tooth surface thus the bulk of plaque by formation of more then one layer of bacterial plaque which: diffusion of salivary bufferes into the plaque. 1 diffusion of acids outside the plaque. Dextranase enzyme can prevent the formation of dexta thus caries Fluoride may also be present in the plaque which helps to: Deposition of fluoride in the form of fluoro appetite Crystals inthe enamel. These crystals has more resistance to the acids than hydroxyappatite. Inhibit bacterial metabolism. So acidogenic theory explains the initiation of cari sbut has no explanation for penetrating caries.  Proteolytic theory: It was found that caries can occur without the PH of dental plaque e.g.: Caries of impacted and unerupted teeth Caries under perfectly seated restorations So it was sugested that the microorganisms attack 1st the organicmaterial feeding on it producing acid which causes demeneralization of the inorganic part of the tooth Organic substance gm -ve decalcification of bacilli sulfuric acid (mucoproteins ) sulfutase enz. Inorganicsubstances This theory explain penetrating caries.  Proteolysis chelation theory: Def of chelation is a processof complexing of a metallic ion into a Complex substance through a highly stable bond e.g. * Haemoglobin is linked to iorn in the blood. *chlorphyl is linked to Mg. both organic and inorganic portions of the tooth are attacked at the same time as following Keratinolytic bacteriacauses break down of proteins in the enamel especially (keratin) resulting in the formation of a substance which forms insoluble chelates vith the inorganic part of the tooth decalcification, desruction of the enamel. This process is independent of the PH of the medium i.e can occurat alkaline or neutral PH. There are some factors which may render this theory unreasonable which are: caries incidence with sugar consumption. lactobacillus counts with caries activity, caries incidence following to systemic or local administration of fluoride, These factors can be explained by:  Chate intake, may be due to the action tcaries with of chate in: Stimulation of proteolysis 1Ca ++chelation. Rendering enamel proteins less stable. caries with lactobacillouscounts may be due to that the micro-organisms are the result and not the cause of caries process.  caries with administration of FI. May be due to the formation of fluroappetite crystals which strengths the bond bet. Inorganic and organicphases of enamel thus preventing or the processof protealysis of chelation. it has been suggested that the proteolysis chelation theory works bet. Meals where the reaction of PH is neutral or alkaline where as during meals the acidogenic theory takes plae