Direct aesthetic restorative materials


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Applied Dental Material
Second Year

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  • Siloranes
    These are composites whose oligomers undergo open ring polymerization
    Therefore they undergo expantion rather than contraction
  • It refers to the amount of filler in the matrix.
  • Direct aesthetic restorative materials

    1. 1. ‫يِ َدْ يِ يِ َّ َدْ يِ ر يِ يِ‬ ‫بسم حاهلل حالرحنمل ن حال َّحميم‬ ‫}وحاحلل عقدة مل ن لسنان ي‬ ‫ِناَ َدْقُ َدْ قُ َدْ ِناَ م ً ِّ ِّ ِناَ يِ‬ ‫}يفقهوحا قول ي }82‬ ‫ِناَ َدْ ِناَ قُ ِناَ َدْيِ‬ ‫}72‬ ‫حالﻌﻅيم صدق حاهلل‬
    2. 2. Aesthetic Restorative Materials
    3. 3. Types of aesthetic restorative materials: Silicate cements. Glass Ionomer. Unfilled Resin.  Filled Resin.  Ceramics
    5. 5. Composition: Powder PMM  Initiator (benzoyl peroxide)  Pigments  Setting reaction: Addition polymerization Liquid Methyl methacrylate together  Chemical activator (dimethyl para toluidine)  An inhibitor (hydroquinone) to prevent polymerization on storage. 
    6. 6.       Disadvantages: Residual monomer Heat evolution Polymerization shrinkage Water sorption Large mismatching in coefficient of thermal expansion &contraction between the filling &the tooth leading to marginal percolation.
    7. 7. Disadvantages:      Aesthetics: Initially excellent aesthetics can be achieved, however, over a period of time, staining is evident at the cavity margins. No adhesive bond between the filling & tooth High volatility Weak mechanical properties Radiolucent
    8. 8. Advantages: It matches the tooth in color, refractive index & translucency. Very limited solubility.
    9. 9. Filled Resin Composite filling material
    10. 10.  A composite is a combination of two or more chemically different materials with a distinct interface separating the components and having properties which could not be achieved by any of the components alone.
    11. 11. Composition 1. 2. 3. 4. 5. Organic matrix phase.(polymeric phase) Inorganic filler phase.(inert phase) Coupling agent which binds the inorganic fillers to the organic matrix Initiator activator systems for organic phase. Other components for organic phase • • • Inhibitors . Ultraviolet stabilizers. Pigments.
    12. 12. Composition: N.B.: For a composite resin material with successful properties,there should be Not less than 50 weight% inorganic filler in the organic matrix. Chemical bond between the inorganic filler&the organic matrix
    13. 13. I. a   Organic matrix phase MW monomer(oligomer) Properties of oligomer: It has the same disadvantages of MMA monomer BUT TO LESSER EXTENT. It produces stronger & stiffer matrix
    14. 14. Type of oligomer: Bisphenol A- glycidyl methacrylate (BIS-GMA) which is called Bowen’s resin. or Urethane dimethacrylates (UDMA). In some products mixture of the two oligomers is present.
    15. 15. The main disadvantage of the oligomer is the high viscosity. Therefore it should be mixed with lower MW monomer(diluent) in ratio of 75% oligomer to 25% monomer.
    16. 16.  b-Low M.W. monomer (diluent)     Reduce the viscosity of the oligomer in order to facilitate Blending with inorganic filler Clinical manipulation Crosslinking between the polymer chains
    17. 17. Recently Ormocer: They are materials polymeric inorganic-organic hybride Inorganic polysiloxane polymer network has been selectively modified by chemically bonded organic methacrylate group.
    18. 18. Advantage:  Less polymerization shrinkage compared to other oligomer.
    19. 19. Other modification Siloranes These are composites whose oligomers undergo ring opening polymerization Therefore they undergo expansion rather than contraction during polymerization
    20. 20. Role of organic matrix: The organic matrix is the soft moldable phase which undergoes addition poly_ merization to form a crosslinked polymer holding the inorganic filler particles together and bonding to tooth structure.
    21. 21. II. Inorganic fillers ( reinforcing fillers) Role: a. • Improvement in mechanical properties such as compressive strength, modulus of elasticity and hardness. • Reduction expansion. • Reduction in the polymerization shrinkage. Less heat evolved in polymerization. • in coefficient of thermal
    22. 22. • • • • • Less water sorption. Less residual monomer. Filler is able to reflect the color of the tooth. The refractive index of the filler matches that of that of the matrix The filler imparts radioopacity.
    23. 23. b) Type of inorganic filler  Quartz: strong,very hard,chemically stable in oral environment,radiolucent.  Fused silica: softer material,easier to grind.  Heavy metal containing glasses: softer material,some types are not stable in oral environment,easier to grind,radioopaque.
    24. 24. c)Filler particle loading and size:
    25. 25. Filler loading: It refers to the amount of filler in the matrix.It can be expressed as volume or weight%. As a guide,the volume % is less than the weight% by 10 -15% ,since the filler is of high density. The filler loading determines the properties of the composite.
    26. 26. For best achievment,we should maximize the filler percentage,keeping in mind that all the filler particles should be wetted by the resin matrix and aiso proper consistency for clinical manipulation should be obtained.
    27. 27. The particle size:  The particle size of the filler and its distribution is important because:  It determines the amount of the filler that can be added without increasing the consistency ;as the smaller the filler,the thicker the consistency i.e.we can not maximize the small filler ,because it will increase the consistency making the clinical manipulation difficult.  It determines the surface finish of the restoration;as the smaller the filler,the smoother the surface finish.
    29. 29. The particle size:  Conventional composite resin: It is a historical type. Particle size:10 -25microns( large particle) Filler loading:70 weight% Comment: Improvement in all properties Poor surface quality due to wear of the resin matrix and protrusion of the filler leading to rough surface,plaque accumulation and discoloration.
    30. 30. The particle size:  Fine composite resin: Both new softer filler type and recent grinding technology allow for the introduction of this and the following types. Particle size:0.4_3 microns Filler loading:75weight% Comment: Improvement in all properties with better surface quality and optical properties.
    31. 31.  Microfine filler : Particle size:0.04_0.2µm(high surface area) Filler loading:only 30weight% without increasing the clinical consistency of the mix Comment: No improvement. What is the solution?
    32. 32. Particle size:0.04_0.2 microns(30%)  + Agglomerated microfine or prepolymerized particles 10_20µm(30%) Filler loading:60 weight% Comment: Best surface finish with less improvement in other properties.
    33. 33.  Hybrid composite:  Particle size:It is a blend of filler sizes to obtain the properties of fine &microfine composites, containing mostly fine particles with 5-15% microfine particles.  This distribution permits more efficient packing, where the smaller particles fill the spaces between the larger particles.  Filler loading: 85 weight%  Comment:  Best properties among all composites.
    34. 34. Recently nanotechnology has been used to produce composite resin with 2-20 nm silica nanoparticles& 0.6µm zirconia_silica nanoclusters.
    35. 35. 3- Coupling agent Force
    36. 36. Type of coupling agent: Silanes Role: It binds the inorganic filler with the organic matrix chemically to enable stresses to be transferred from particle to adjacent particles through the organic matrix i.e.all act as one unit. But this bond degrades, when water is absorbed by the composite intraorally.
    37. 37. Initiator Activator System Role of initiator activator system: To cause addition polymerization of the organic matrix. Types of initiator activator system:
    38. 38. Initiator Activator System a. Chemical activation: Self-,cold-,automatic cured(initiated) Aromatic tertiary amine activate benzoyl peroxide to produce free radicals. b. Light activation: Photo cured( initiated) There are 2 types: a. Ultra violet activation (not used because of health hazards&limited depth of cure)
    39. 39. b. Blue visible light activation:  ~470 nm wavelength
    40. 40. Diketone In the presence of blue visible light Excited state In the presence of aliphatic tertiary amine Free radical
    41. 41. Comparison: Chemically cured C.R. Light cured C.R.  Supplied as 2 pastes.  Proportionong.  Mixing.  Air inclusion.  Human variables.  Limited working time,as  Supplied as one paste.  No proportioning setting starts after mixing immediately  Less colour stable due to oxidation of aromatic tertiary amines  Bulk insertion  No mixing  No air inclusion  No human variables  Long working time,as setting starts upon light irradiation  More colour stable due to presence of aliphatic tertiary amines& even in less amount
    42. 42. The depth of cure : Definition: It is the thickness of C.R. completely penetrated by the visible blue light & polymerized. Factors affecting the depth of cure: 1. The intensity of the light source(normal output is 400J/cm square) 2. The exposure time( normal exposure time is 20_40 seconds) 3. The distance between the light source & the restoration(ideal is 1mm with the light source positioned 90degrees from the C.R.surface.
    43. 43. The depth of cure : 4. The type of C.R. regarding: a) The shade( lighter shade has greater depth of cure) b) The filler size & loading(the larger the filler with greater loading to certain extent,the greater depth of cure) c) The absorption coefficient of initiator activator system(light sensitivity&amount) 5. Air inhibition
    44. 44. N.B. Care should be taken to avoid unpolymerized material in the base of cavities . Composite resin which is not fully polymerized will show reduced mechanical properties, poorer colour stability and greater susceptibility to stain.
    45. 45. N.B. Not all the available carbon double bond in the organic matrix convert into single bond;~25% remain uncoverted in the bulk of the restoration. Keep in mind, the higher the degree of conversion,the better the properties of C.R.
    46. 46. A.Polymerization inhibitor: i. It extends the shelf life by preventing premature polymerization. ii. It provide suitable working time. B. Ultraviolet stabilizer: It protects against yellowish discoloration by time. C .Fluorescent agent&Pigment: To simulate the tooth
    47. 47. Classification of C.R.: According to filler size & loading According to initiation activation system According to method of application According to handling
    48. 48. a) According to filler size & loading: 1) Conventional C.R. 2) Fine C.R. 3) Microfine C.R. 4) Hybrid C.R.
    49. 49. b- According to initiation activation system: • Chemically cured composite • Light cured composite • Dual cured composite:It is applied in resin cement & indirect restoration.( combination of heat,chemical or light curing)
    50. 50. C )Restorations Direct restorations Indirect restorations
    51. 51. Composite inlay:  composite inlay systems are polymerized outside or inside the patient mouth and then removed from the prepared cavity by the help of separating medium.  The inlay is then subjected to post-curing by additional light (6minutes) or heat (about 100°C for 7 minutes).  The preparation is etched.  The inlay is then cemented to the prepared cavity with a dual cure resin and is then polished.
    52. 52.  Purpose of indirect restoration (laboratory composites) I. Increase degree of conversion of oligomer to polymer by dual curing thus increasing the mechanical properties&colour stability. 2. No weakening effect on tooth composite bond,as the polymerization shrinkage of the C.R. occurs completely outside the patient s mouth.  N.B. • Only the polymerization shrinkage of the thin film of the resin cement ,used for the cementation of the indirect restoration ,occurs inside the patient s mouth.
    53. 53. d) According to handling:Regarding the filler size,shape&loading beside resin formulation,there are2 types:  Flowable C.R.:It has very low viscosity& high flow allowing for better adaptation.It is used for cervical lesion,pediatric lesion&in combination with packable C.R. Packable C.R.:It has very high viscosity&low surface tackiness.It can be compressed against the cavity walls&margins for proper adaptation.It can be used for class one& class two. 
    54. 54. Properties of C.R.: The properties of C.R. is related tothe 1)amount of inorganic filler,as it reduces the percentage of the organic matrix & consequently its disadvantages. The inorganic filler acts as mechanical skeletal structure within the C.R. to maintain the original amount. 2)The degree of conversion of carbon double bond into single bond in the organic matrix.The higher the degree of conversion,the better the properties C.R.
    55. 55. 1) Biological properties: C.R. is irritant to the pulp because of heat evolution,shrinkage&residual monomer during polymerization reaction. Therefore C.R. should be lined by calcium hydroxide. The irritation ranking is as follows: microfilled>conventional>fine>hybrid.
    56. 56. 2) Solubility&water sorption:      Composites have a very low solubility. But it absorb water due to its polarity. The ranking of water sorption is a follows:microfilled>conventional>fine>hybrid N.B. UDMA shows less water sorption Some inorganic filler are more liable to hydrolyti degradation than others, e.g.barium,strontium containing glasses.
    57. 57. 3)Dimensional changes on setting:  C.R. undergo polymerization shrinkage,,due to closer spacing in the polymer when compared to that in the oligomer.  The ranking of polymerization shrinkage is as follows: microfilled>conventional>fine>hybrid.  The consequences of polymerization shrinkage are : - Weakening of tooth composite bond - Marginal leakage - Discoloration - Recurrent caries  These can be reduced by: 1)Incremental filling(light cured) 2)Indirect restoration 3)Curing mode (light intensity is delivered at
    58. 58. 3)Dimensional changes on setting: slow rate to allow for the flow of C.R.relieving the polymerization stresses. 4)Water sorption 5)Use of elastic wall concept by the application of intermediate lining of lower elastic modulus. 6)Use of ormocer or silorane 7)Establish strong bond between the tooth&C.R.
    59. 59. 4) Thermal properties: Thermal conductivity: The thermal conductivity values are lower than those for metallic restorations . It is related to the higher conductivity of the inorganic fillers compared with the organic matrix. The ranking is as follows: Hybrid>fine>conventional>microfilled. However it does not present a clinical problem.
    60. 60. 4)Thermal properties: Coefficient of thermal expansion: It is~double than that of tooth structure. The ranking is as follows: Microfilled>conventional>fine>hybrid This mismatch leads to the same consequences as in polymerization shrinkage
    61. 61. 6- Mechanical properties: C.R is a brittle material,i.e. stronger in compression than in tension.  Polymerization may continue for 24 hours after clinical curing,thereby improving in mechanical properties  The ranking is as follows: Hybrid>fine>conventional>microfilled 
    62. 62. 7) Aesthetic and optical properties:    Aesthetic is initially excellent;but by time there will be discoloration because of the following: Oxidation of aromatic tertiary amine in self cured C.R. The polymer matrix wears more rapidly than the inorganic filler leading to rough surface&accumulation of plaque&stains
    63. 63. Water sorption of C.R. leads to partial debonding of the inorganic filler&stress cracks in the polymer matrix decreasing the translucency of the material. Polymerization shrinkage leading to marginal ieakage. Mismatching in coefficient of thermal expantion &contraction between the tooth &C.R.leading to marginal leakage.
    64. 64. Only theC.R. with heavy metal containing glasses e.g.barium,boron,strontium,zirconium,oryetribium are radioopaque to detect defective filling&recurrent caries. The ranking of best surface finish against the plastic matrix is as follows: Hybrid>microfilled>fine>conventional
    65. 65. 8) Bonding and retention to tooth structure: Bonding to enamel: It is a micromechanical attachment with the following steps:  Acid etching to produce surface irregularities  Bonding agent to enable penetration of the C.R.&bonding to it. 
    66. 66. Bonding to dentin: It is a micromechanical attachment with the following steps: Etching to produce surface irregulrities &to remove smear layer Application of primer to wet the dentin & to bind to the bonding agent Application of bonding agent
    67. 67. 9)Shelf life: All C.R. have a limited shelf life~2years. Therefore C.R. should be stored under refrigeration & allowed to come to room temperature for ~1hour before use. Light cured C.R.should be stored away from ambient light. C.R. contain volatile components. Therefore C.R.should be dispensed immediately before use &resealed also immediately.
    68. 68. Applications of composites:       Direct anterior restorations. Direct posterior restorations Core build up materials Provisional restorations Lower viscosity C.R. used as pit & fissure sealant,luting &bonding agents Laboratory C.R. for indirect restoration These may contain fibres instead of particles.
    69. 69. Setting reaction: