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Almaaqal University Medical Chemistry Collage of Dentistry Lipids and Teeth Diseases Dr/ Wael Sobhy Darwish 1ST stage&2024  Introduction to lipids Definition: Lipids...

Almaaqal University Medical Chemistry Collage of Dentistry Lipids and Teeth Diseases Dr/ Wael Sobhy Darwish 1ST stage&2024  Introduction to lipids Definition: Lipids are hydrophobic small molecules, formed from alcohol and fatty acids combined together by ester bond. Including fats, waxes, sterols, fat-soluble vitamins, and phospholipids. Lipds are insoluble in water but soluble in organic solvents i.e. ether, benzene, acetone & chloroform.  Lipids ARE LIPIDS BAD? DO THEY HAVE ANY FUNCTION?  Biomedical Importance of Lipids 1. Source of energy: (Lipids have a high energy value). 2. Structural components of cell membranes (phospholipids and cholesterol). 3. Metabolic regulators (e.g. steroid hormones). 4. Help in absorption of fat-soluble vitamins (A, D, E and K). 5. Protect internal organs by providing a cushioning effect (pads of fat). 6. Provide insulation against changes in external temperature (subcutaneous fat). Classification of lipids  Simple lipid ❖ Definition: Are esters of fatty acids with various alcohols. (Ester bond = -COO-). They are either fats or waxes Fatty acids are water-insoluble “long chain hydrocarbons” Fatty acids may be Saturated: or Unsaturated: - Fatty acids may be Essential: cannot be synthesized in the body or Nonessential: can be synthesized in the body.  Saturated & Unsaturated fatty acids i. Saturated fatty acids - Have no double bonds in the chain. - Their general formula is CH3- (CH2) n -COOH where (n) equals the number of methylene (-CH2) groups between the methyl and carboxylic groups. -  Unsaturated fatty acids: Contain one or more double bond - Unsaturated fatty acids are either monounsaturated or polyunsaturated. ❖ Monounsaturated fatty acids i.e. contain one double bond e.g. palmitoleic acid Polyunsaturated fatty acids Containing more than one double bond - PUFA are classified according to the position of the 1st double bond in relation to ω carbon into ω3, ω6, ω7 & ω9 F.A. ▪ ω3 PUFA: PUFA having the 1st double bond at carbon 3 in relation to ω carbon Contains one double Contains bond more than one double bond Functions OF PUFA : 1.Useful to prevent atherosclerosis. 2.Prostaglandin & eicosanoids are synthesized 3.They participate in structure of all cellular and subcellular membranes and the transporting plasma phospholipids. 4.Essential for skin integrity, normal growth and reproduction. 5.Important role in blood clotting. 6.Important in preventing and treating fatty liver. 7.Important role in health of the retina and vision. 8.They can be oxidized for energy production. Rancidity Definition: - It is a physico-chemical change in the natural properties of the fat leading to the development of unpleasant odour or taste or abnormal color after exposure to atmospheric oxygen, light, moisture, bacterial or fungal contamination and/or heat. Types and causes of Rancidity: 1.Hydrolytic rancidity 2.Oxidative rancidity 3.Ketonic rancidity 1-Hydrolytic rancidity: Due to hydrolysis of the fat by lipase from bacterial contamination at high temperature and moisture. 2-Oxidative Rancidity: Due to exposure to oxygen, light and/or heat producing peroxide derivatives that are toxic and have bad odor. 3-Ketonic Rancidity: due to contamination with fungi.  Prevention of rancidity is achieved by: 1.Avoidance of the causes (exposure to light, oxygen, moisture, high temperature and bacteria or fungal contamination). 2.By keeping fats or oils in well-closed containers in cold, dark and dry place. 3.Addition of anti-oxidants. The most common natural antioxidant is vitamin E. Hazards of Rancid Fats: 1.The products of rancidity are toxic, i.e., causes food poisoning and cancer. 2.Rancidity destroys the fat-soluble vitamins (vitamins A, D, K and E). 3.Rancidity destroys the polyunsaturated essential fatty acids. 4.Rancidity causes economical loss because rancid fat is inedible (Unfit to eat).  Simple Lipds They are called simple because they are formed only from alcohols and Fatty acids. There are two classes of simple lipids (according to the type of alcohol): Acylglycerols & Waxes - Acylglycerols are esters of one, two or three fatty acids with glycerol - Waxes: combination of fatty acids +Long chain alcohol They are not digested by lipase enzyme. They are solids at room temperature.  Compound lipids Compound lipids contain in addition to esters of fatty acids with alcohols, other groups. According to the type of the group attached, they are classified into: Compound Lipids Phospholipids Glycolipids Sulfolipids Lipoproteins  Derived Lipids Derived lipids: When both simple and compound lipids combine and undergo the process of hydrolysis, the produced chemical is known as the derived lipids. Derived lipids include cholesterol, carotenes, steroids and prostaglandins, ketone bodies, and Fat soluble vitamins (Vit. K, E, D & A)  The role of lipids in teeth diseases The total lipid fraction of saliva is predominantly neutral lipids, Lipids in saliva include: free fatty acids, cholesterol, cholesterol esters, monoglycerides, diglycerides, and triglycerides. This composition can influence the interactions of lipids with the initial oral biofilm and the pellicle layer, affecting the overall oral health. Salivary lipids have been linked to certain oral diseases caused by the oral environment and bacteria during dental caries or dental calculus.  Lipids and Dental Calculus: The main ingredient of dental calculus is minerals, but it also contains organic components like proteins and lipids. Teeth lipids contain high amounts of free fatty acids and less triglycerides, glycolipids, and phospholipids. People with more calculus have a higher lipid rate in their saliva than those with less calculus. Lipids and Early Childhood Caries Lipids can increase glucoseyltransferase enzyme activity, enhancing the cariogenic potential of oral microorganisms. The total lipid and triglyceride levels in the saliva of children with caries are higher compared to children without caries.