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Pedia dental materials

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Pediatric Dentistry I …

Pediatric Dentistry I
Forth Year


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  • 1. • No truly adhesive dental material. No restorative dental material exactly duplicates the physical properties of tooth structure. • Gap between the walls of the prepared cavity and the restoration interrupt acid, food debris, and microorganisms. • Microleakage may be the precursor of secondary caries, marginal deterioration, postoperative sensitivity, and pulp pathology. Dental materials
  • 2. • Microleakage is problem in the pediatric patient because the floor of the cavity preparation may be close to the pulp • Insult to the pulp caused by the seepage of irritants that penetrate around the restoration and through the thin layer of dentin, or a microscopic pulpal exposure, may produce irreversible pulp damage. Dental materials
  • 3. • For true adhesion • Bonding chemical adhesion • Materials are the polycarboxylate and glass ionomer cements. • No need for the typical cavity preparation because adhesion eliminate the need for mechanical retention by the cavity preparation. No need for auxiliary aids, as cavity varnishes and etching techniques, to minimize the microleakage around direct filling restorations. Dental materials
  • 4. • the surface energy of most restorative materials, metallic ones, is higher than of normal intact tooth structure. Therefore, debris accumulates on the surface of restorations more than on the adjoining enamel high incidence of secondary caries associated with most restorative materials, except for those that release fluoride ion. Dental materials
  • 5. Dental materials • For disinfection procedures. Most materials are now packaged for unit-dose delivery at chair side, which makes infection control much easier. • Safety handling any hazardous materials • Environmental safety for all waste discharged from the dental office. Disposal of hazardous materials.
  • 6. Dental Material Properties WettabilitySolubilityGalvanismCorrosion ViscosityRetentionFlow Biting forces Thermal expansionMicroleakageElasticityAdhesion ThermalHardness Dimensional changeAcidity
  • 7. Biting Forces
  • 8. Materials Preparing for Restoration Liner BasesVarnish Cements Bonding agents
  • 9. Dental Cements Varnish Sedative Base Liner Luting Cements
  • 10. Cavity varnish • When varnish is painted onto the cavity preparation, the solvent evaporates and leaves a thin resin film. • The varnish reduce microleakage
  • 11. Copalite Varnish
  • 12. • CEMENTS BASE • LUTING CEMENTS – ZINC PHOSPHATE CEMENT setting time, fluidity, moderate degree of intraoral solubility and film thickness. – It does not have an anticariogenic effect, does not adhere to tooth structure & irritant to the pulp. • POLYCARBOXYLATE CEMENT – a chemical bond is formed between the cement liquid and the calcium in the hydroxyapatite in enamel and dentin. – To remove smear layer cleaning the surface is a 10- to 15-second swabbing with 10% polyacrylic acid. – the mix should be completed within 30 seconds. – If the mix is too thick, insufficient acid is present to produce bonding to the tooth. – If excess liquid is used, the intraoral solubility increases significantly. CEMENTS
  • 13. CEMENTS • GLASS IONOMER CEMENT • restorative material (type II) , as a luting agent (type I), and as a base and liner material (type III). • The powder is a fluoro-aluminosilicate glass with maleic acid, • luting agent for cast restorations, GIC has been employed for bonding orthodontic brackets to acid-etched enamel • RESIN-MODIFIED GLASS IONOMER CEMENTS • a comonomer of acrylic acid and a methacrylate such as hydroxyethyl methacrylate in the same manner as light- activated restorative resin composites.
  • 14. CEMENT BASES • Zinc phosphate, hard-setting calcium hydroxide, zinc oxide—eugenol, and glass ionomer cements have sufficient strength to serve effectively
  • 15. CEMENT BASES • The function of the cement base is to promote recovery of the injured pulp and to protect it against further insult. • The base serves as a thermal insulator an replaces missing dentin when it is used under the metallic restoration. • A base must be able to support the condensation of the restorative material placed over it.
  • 16. Cement base • A minimum thickness of cement to promote recovery of the injured pulp and to protect it against further insult approximately 0.5 mm • able to support the condensation of the restorative material placed over it.
  • 17. Luting Cements • Permanent • Temporary • Intermediate Compomer Resin Glass Ionomer Polycarboxylate Zinc Oxide Eugenol Zinc Phosphate Luting
  • 18. Temporary & Permanent Restorations • Biologic characteristics, have minimal solubility, and be rigid, strong, and resistant to abrasion. – zinc oxide-eugenol cement mixture with polymers – Type II glass ionomer cements or the newer resinmodified GICs
  • 19. Resin based composites (RBC) • Resin matrix (Bis-GMA) with inorganic filler particles. 1. Filler content- • Filled vs Unfilled • Flowable vs packable • Anterior vs posterior composite 2. Particle size macro, microfilled and hybrids
  • 20. Restorative Resins •CONVENTIONAL COMPOSITES matrix is bisphenol A-glycidyldimethacrylate (bis- GMA) or urethane dimethacrylate resin. Triethylene glycol dimethacrylate, a lower-viscosity resin 70-80% macro fillers are ground particles of fused silica, crystalline quartz, and soft glasses such as barium, strontium, and zirconium silicate glass (reduces the coefficient of thermal expansion & polymerization shrinkage and increases the hardness). •MICROFILLED COMPOSITES –small silica filler particle, 0.02 to 0.04 μm, microfine, microfilled, or polishable resins •SMALL-PARTICLE AND HYBRID COMPOSITES –radiopaque glass particles with an average size of 0.6 to 1.0 pm in addition to 10%-20% colloidal silica. The total filler level, 70% to 80%,
  • 21. • LIGHT-CURED COMPOSITES • POSTERIOR COMPOSITE RESTORATION • The improved strength, hardness, and modulus of elasticity of some of the newer composite resins, with their low thermal conductivity and superior esthetics, indicate that they may serve as alternatives for amalgam in the restoration of occlusal and proximal surfaces in posterior teeth clinical wear of less than 20 μm per year over a 5-year period. Restorative Resins
  • 22. Resin Restorations Steps: Etch, wash, dry or dessicate? Enamel and Dentin adhesives Composite selection and placement Curing tools and techniques Disadvantages: 1. Polymerization shrinkage 2. Technique sensitive 3. Performance of posterior composites in large, stress bearing preparations is questionable
  • 23. Dentin/Enamel adhesives in Pediatric Dentistry Dentin bonding agents or Primers: Smear layer Etch Hydrophillic and hydrophobic component (HEMA) Enamel adhesives or bonding agents: Hydrophobic resin such as Bis-GMA Hybrid layer copolymerized Layer of primer, bonding resin and collagen 1. 3-step total etch 2. Total etch using prime and bond 3. Self etch primers with bonding agent 4. All-in-one adhesives e.g.- prompt Lpops
  • 24. Acid-Etching Technique • The enamel is etched with a solution of phosphoric acid (35%) for 15 to 20 seconds or gel. • Rinse to remove the debris produced during etching. A minimum wash time of 30 seconds • The etched surface must then be dried for at least 15 seconds. • If the surface is accidentally contaminated by saliva. Rather, the surface should be re- etched for 10 seconds, washed, and dried. • Resin bond strengths to etched enamel range from 16 to 22 MPa.
  • 25. Bonding Agents •bis-GMA resin matrix material diluted with a low-viscosity methacrylate monomer.
  • 26. Amalgam No polymerization shrinkage Moisture forgiving Excellent mechanical properties Mercury toxicity Esthetics
  • 27. Amalgam • SELECTION OF THE ALLOY – Lathe-cut alloys – Spherical alloys. amalgamate very readily with smaller amounts of mercury & gains strength more rapidly • HIGH-COPPER ALLOYS – The original dental amalgam alloys were alloys of silver and tin with a maximum of 6% copper. – High-copper amalgam alloys have (11% to 30%) copper have low creep. – Creep is the tendency of a material to deform continuously under a constant applied stress. This associated with the marginal breakdown (ditching). – Dental amalgam permits a maxi-mum of 3% creep, a modern high-copper amalgam alloy should not exceed 1% creep.
  • 28. • MERCURY/ALLOY RATIO – Pre-filled, disposable mixing capsules containing the proper amounts of alloy and mercury. • The alloy/mercury ratio is accurately preproportioned. • The need for disinfection procedures is minimized (capsule is discarded after use). • Exposure of dental personnel and environmental contamination by mercury vapor is minimized. • TRITURATION – Depend on the composition of the alloy, the mercury/alloy ratio, the size of mix, – Undertriturated mix appears dry and sandy and does not cohere into a single mass. • Set too rapidly, • Results in a high residual mercury content, reduced strength, and • The increased of fracture or marginal breakdown. Amalgam manipulation to control of mercury
  • 29. Amalgam • MECHANICAL AMALGAMATORS • Trituration speed, time, significantly influences the rate at which some amalgams • CONDENSATION • to adapt the amalgam to the walls of the cavity preparation, • to minimize the formation of internal voids, & • to express excess mercury from the amalgam. • MOISTURE – If zinc is present in the alloy, react with water, and hydrogen gas will be formed lead to delayed expansion – zinc-free, high-copper alloy should be used where moisture control is difficult. • MARGINAL BREAKDOWN AND BULK FRACTURE
  • 30. Amalgam • BONDED AMALGAM RESTORATIONS • MERCURY TOXICITY • Dental personnel potentially are exposed daily to mercury through skin or by ingestion, the primary risk is from inhalation • The maximum level considered safe for occupational exposure is 50 p.g of mercury per cubic meter of air averaged over a standard 8-hour workday. • The dental operatory should be well ventilated. • All mercury waste and amalgam scrap removed during placement or removal of amalgam restorations should be collected and stored in well-sealed containers. • When amalgam is cut, water spray and high-speed evacuation should be used.
  • 31. Preventive Materials 1. Fluoride gels, foam and varnish: Used for remineralization of decalcified enamel and incipient caries. 2. Sealants: Indicated for preventing and arresting incipient lesions. Available as clear or white, filled or unfilled, containing Fluoride or not.
  • 32. SSC- Primary and Permanent • Full coverage, metallic, definative restorations • Available as: pretrimmed (Unitek ), precontoured and festooned (Ni- ChroION crowns) • Durable and costeffective
  • 33. Summery • Primary teeth are a temporary dentition with known life expectancies of each tooth. By matching the ‘right’ restoration with the expected lifespan of the tooth, we can succeed in providing a ‘permanent’ restoration that will never have to be replaced.”