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Calcium hydroxide cements
Calcium hydroxide cements were introduced by Hermann in 1920 as an alternative to viewing exposed pulps as "doomed organs." Calcium hydroxide cements promote healing in clinical situations by creating an alkaline environment. They are formed through a reaction of calcium oxide with water to create calcium hydroxide. Typical calcium hydroxide cements are composed of calcium hydroxide, zinc oxide, zinc stearate, and ethyl toluene sulphonamide. They set through exothermic chemical reactions, have biocompatibility that can destroy bacteria and initiate reparative dentin formation, but have low strength and solubility in moisture.
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Calcium hydroxide cements
- 1. 4/19/2020 1 Calcium HydroxideCements Professor DR. Tahir Ali Khan
- 2. 4/19/2020 2 Rebel summarizedhis thoughts in the expression “the exposed pulp is a doomed organ” Once pulp exposed Consider it a lost organ
- 3. 4/19/2020 3 Hermann’s (1920)introduced Calcium hydroxide formulation The emphasis has shifted from “Doomed Organ” concept of an exposed pulp To one of hope and recovery
- 4. Calcium hydroxide Limestone: Anatural rock Composed of calcium carbonate (CaCO3) The combustion of limestone between 900ºC and 1200ºC causes the following chemical reaction: CaCO3 → CaO + CO2 4/19/2020 4
- 5. How Calcium hydroxideformed CaO + H2O → Ca(OH)2 Strong alkali White odorless powder Formula: Ca(OH)2 Molecular weight: 74.08 4/19/2020 5
- 6. 4/19/2020 6 History Introduction todentistry by Hermann Indicated to promote healing in many clinical situations. Initially Nygren (1838) used it for the treatment of the `fistula dentalis', Codman (1851) was the first to attempt to preserve the involved dental pulp.
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- 8. 4/19/2020 8 Calcium hydroxidecements Presentation Powder Powder / Liquid Paste / Paste Single paste
- 9. Classification Based on thesetting time Fast setting Controlled setting Slow setting No setting 4/19/2020 9
- 10. Based on mechanismof setting Self curing Light curing . 4/19/2020 10
- 11. Based on vehicleused Aqueous vehicle Water, saline, dental anesthetic, ringers solution, aqueous suspension of methylcellulose Viscous vehicle Glycerine, polyethylene glycol and propylene glycol. • Oily vehicles – Olive oil, oleic acid, linoleic 4/19/2020 11
- 12. Composition 1. Suspension ofCalcium hydroxide in water 2. Calcium hydroxide + water + methyl cellulose 3. Calcium hydroxide + synthetic resin + chloroform 4/19/2020 12
- 13. 4/19/2020 13 Composition oftypical Calcium Hydroxide Cement Paste 1 Calcium hydroxide 50 % Function: Primary reactive ingredient Zinc oxide 10 % Function: Primary reactive ingredient Zinc Stearate 0.5 % Function: Accelerator Ethyl Toluene Sulphonamide 39.5 % Function: Oil compound acts as carrier
- 14. 4/19/2020 14 Composition oftypical Calcium hydroxide cement Paste 2 Glycol Salicylate 40 % Function: Primary reactive ingredient Titanium dioxide Calcium Sulphate Calcium Tungstate Function: Inert fillers, pigments and radio pacifiers
- 15. Composition of lightactivated Calcium hydroxide cement Calcium hydroxide Bis GMA HEMA Activator 4/19/2020 15
- 16. 4/19/2020 16 Properties Manipulative properties Themixed material have very low viscosity Setting can be relatively slow for some products Moisture has a dramatic effect on the rate of setting however, material can set within few seconds of being placed in cavity
- 17. 4/19/2020 17 Setting oflight cured material is under the operator control During setting Temperature rises due to Heating effect of light source Reaction is Exothermic
- 18. 4/19/2020 18 Mechanical properties Weakcement Compressive strength is 20 MPa
- 19. 4/19/2020 19 At 7minutes The compressive strength : 6 MPa The tensile strength :1.5 MPa At 1 hour The compressive strength :10 MPa The tensile strength:1.5 MPa (200 psi) At 24 hours The compressive strength :14 to 20 MPa The tensile strength :1.7 to 2 MPa Thin films become resistant to 8 Mpa penetration force in 90 seconds At 37 deree celciuos plastic flow without fracture occurs
- 20. 4/19/2020 20 Biocompatibility It issufficiently biocompatible To be placed adjacent to the pulp and capable of destroying any remaining bacteria
- 21. 4/19/2020 21 The materialis bioactive Irritation of the pulp tissues Mediated by the activation of a cellular growth factor (TGFβ) Initiate Calcification and formation of Tertiary dentin
- 22. 4/19/2020 22 Solubility Set materialshave relatively high solubility in aqueous media Resin based Calcium hydroxide cement are less soluble than conventional products but still Calcium hydroxide release remain great enough
- 23. 4/19/2020 23 Application As liningand base agent As a pulp capping agent Therapeutic root canal sealer
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- 29. 4/19/2020 29 Advantages Easy manipulation, Rapidhardening in thin layers, Good sealing characteristics, and Beneficial effects on carious dentin and exposed pulp.
- 30. 4/19/2020 30 Disadvantages Show lowstrength even when fully set, Exhibit plastic deformation, Are weakened by exposure to moisture, and Will dissolve under acidic conditions and if marginal leakage occurs
Editor's Notes
- #5 Limestone: A natural rock mainly composed of calcium carbonate (CaCO3) which forms when the calcium carbonate solution existing in mountain and sea water becomes crystallized The combustion of limestone between 900ºC and 1200ºC causes the following chemical reaction: CaCO3 → CaO + CO2
- #6 Can be formed by the reaction of calcium oxide The calcium oxide (CaO) (quicklime) contacts water, the following reaction occurs Calcium hydroxide is a white odorless powde
- #7 the initial reference to its use has been attributed to Nygren (1838) for the treatment of the `fistula dentalis',
- #12 Aqueous vehicle Water, saline, dental anesthetic, ringers solution, aqueous suspension of methylcellulose Viscous vehicle Glycerine, polyethylene glycol and propylene glycol. • Oily vehicles – Olive oil, oleic acid, linoleic and isosteric acid
- #16 DMAEMA
- #21 Calcium hydroxide acts as Antibacterial And got alkaline pH Calcium hydroxide is readily leached out Generating an alkaline environment in the area surrounding the cement This is thought to be responsible for the proven antibacterial properties of these materials The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes.
- #22 The material is bioactive Initiate Calcification and formation of Tertiary dentin due to Irritation of the pulp tissues by the cement, possibly mediated by the Activation of a cellular growth factor (TGFβ)