Composite Restoration Materials Lecture 4 PDF

History of resinous material (Unfilled Acrylic Resin) Self-curing (chemically activated) acrylic resin for anterior...

History of resinous material (Unfilled Acrylic Resin) Self-curing (chemically activated) acrylic resin for anterior restorations was developed in Germany in the 1930s. Early acrylic materials were disappointing due to: 1. Poor activator systems. Composite Restoration(1) 2. High Polymerization shrinkage. 3. High coefficient of thermal expansion. 4. High wear. By: Dr. Rehab Alwakeb Operative Dentistry Division Introduction (Acrylic resin) A current, although limited, use of acrylic resin is: which resulted in: for making temporary restorations in operative 1. Marginal leakage. and fixed prosthodontic “indirect restoration 2. Pulp injury. procedures fabrication” requiring two or more appointments. 3. Recurrent caries. 4. Color changes. In an effort to improve the physical characteristics 5. Loss of contour and contacts. of unfilled acrylic resins, a polymeric dental restorative material reinforced with inorganic So, are they still being used?? particles was introduced in 1962 (by Bowen). This filled resin material became the basis for the restorations that are termed composites. I. definition: Dental Composite material 1. Definition. 2. Components. Composite is a material made from two or more 3. Classification: constituents with significantly different physical or chemical properties that, when combined, produce a a. According to filler (size, amount and material with characteristics different from the individual composition). components. b. According to Handling characteristics II. Components: III. classification: Matrix Initiators and Filler Accelerators Coupling Agent Pigments a. According to filler size Macrofil Microfil Hybrid Nanofilled  1. Macrofilled or Conventional Composites They are no longer used in clinical practice Contains approximately 75-80% inorganic filler by weight. The average particle size of this composites was approximately 8 μm. as it suffers of rough surface texture. causes the restoration to be more susceptible to discoloration from extrinsic staining 2. Microfilled composite: Properties: Some of their physical and mechanical Microfill composites were introduced in the characteristics are inferior. late 1970s. These materials were designed to replace the Clinically highly wear resistant. rough surface characteristic of conventional Low modulus of elasticity may allow microfill composites with a smooth, lustrous surface composite restorations to flex during tooth flexure, similar to tooth enamel less susceptible to better protecting the bonding interface. plaque retention and discoloration. Filler particle size: colloidal silica particles whose average diameter is 0.01 to 0.04 μm. This makes micro-fill composites an appropriate Filler content: approximately 35% to 60% by choice for restoring Class V cervical lesions or weight. defects in which cervical flexure can be significant (e.g., bruxism, clenching, stressful occlusion). 3. Hybrid composite: Hybrid composites were developed in an effort to combine the favorable physical and mechanical properties characteristic of macrofill composites with the smooth surface of the microfill composites. Filler size: mixture of microfiller and small filler particles that results in a considerably smaller average particle size (0.4–1 μm) than that of conventional. Filler content: 75-85% by weight Properties: Because of the relatively high content of inorganic fillers, the physical and mechanical characteristics are generally superior to those of conventional composites. Classic versions of hybrid materials exhibit a smooth “patina-like” surface texture in the finished restoration. Nanohybrid composites: these are newer versions of hybrid composites contain ultra-small nanofillers, resulting in superior characteristics.  4. Nanofill composites Filler particles size are extremely small Nanofill and Nanohybrid composites are the most (0.005–0.01 μm). popular composite restorative materials in use. Consequently, high filler levels can be These composites have almost universal clinical generated in the restorative material, which applicability results in: 1. Good physical properties 2. Improved esthetics. 3. The small primary particle size also makes nanofills highly polishable Wear Comparison: III. Classification (cont.) Porous friable nanoclusters Lightly sintered b. According to handling ccc Flowable Packable Hybrid-wear True Nano wear 1.Packable composite 2. Flowable composite Their development is an attempt to accomplish Easier restoration of a proximal contours and contacts and Generally, have lower filler content and consequently inferior physical properties such as: Because of the increased viscosity, it is typically more difficult to attain optimal marginal adaptation. 1. lower wear resistance. 2. Lower strength. 3. They also exhibit much higher polymerization shrinkage. WHY? Due to decreased filler loading thus Decrease viscosity Decrease mechanical properties Increased polymerization shrinkage.  Uses: IV. Properties: 1. Pit-and-fissure sealants, 2. Marginal repair materials. 1. Linear Coefficient of Thermal 3. First increment placed as a stress-breaking liner Expansion. under posterior composites. 2. Water sorption. 4. First small increments in the proximal box of 3. Wear Resistance. Class II restoration in an effort to improve marginal adaptation. 4. Surface Texture. 5. Radiopacity. 6. Modulus of Elasticity 7. Polymerization. 1. Linear Coefficient of Thermal Expansion 2. Water sorption: the rate of dimensional change of a material per unit Water sorption is the amount of water that a change in temperature. material absorbs over time per unit of surface The LCTE of modern composites is approximately area or volume. three times that of tooth structure. Materials with higher filler contents exhibit Bonding a composite to etched tooth structure reduces lower water absorption values than materials negative effects due to difference between the LCTE with lower filler content. of the tooth structure and that of the material Incompletely cured composites exhibit higher water absorption values causing bulk discoloration. 3. Wear Resistance 4. Surface Texture Wear resistance refers to a material’s ability to resist surface loss as a result of abrasive contact Surface texture is the smoothness of the with opposing tooth structure, restorative surface of the restorative material. material, food bolus, and such items as Nanohybrid and Nanofill composites also toothbrush bristles and toothpicks. provide surface textures that are polishable, Wear resistance of contemporary composite esthetically satisfying, and compatible with materials is generally good. soft tissues. So, esthetical and biocompatible. 5. Radiopacity 6. Modulus of Elasticity Esthetic restorative materials must be sufficiently is the stiffness of a material. A material having a higher modulus is more rigid; conversely, a material with a radiopaque so that the radiolucent image of recurrent lower modulus is more flexible. caries around or under a restoration can be seen more easily in a radiograph. Clinical application: This is particularly true for Class V restorations in teeth Most composites contain radiopaque fillers such as experiencing heavy occlusal forces, where stress barium glass to make the material radiopaque. concentrations exist in the cervical area. Such stress can cause tooth flexure that can disrupt the bonding interface. Using a more flexible material such as a microfill composite allows the restorations to bend with the tooth, better protecting the bonding interface  A 17-year-old girl presents to the Dental Clinic Abfraction complaining of black spot on facial surface of upper front tooth. Clinical examination reveals small size cervical caries in teeth # 22. Class V composite restoration is the treatment of choice. Which composite is the best used? Nanofilled/Nanohybrid Light curing 7. polymerization: Diketone initiators such as camphoroquinone photo-initiator. It is activated by wavelengths in the range of 370-500 nm with the peak It is a chemical reaction where low molecular weight monomer at 468 nm (blue region of the visible spectrum). It dissociate into molecules are converted to high molecular weight polymer radicals upon irradiation. chains. The two polymerization methods are (1)the self-cured method (2)the light-cured method using visible light. Curing devices Quartz, tungsten halogen light-curing systems ccc by decreased efficiency with time. Plasma arc curing systems provide high-intensity and high-speed curing compared with the quartz, tungsten systems. However, they also significantly increase the stresses from heat generation and polymerization shrinkage. Light-emitting diodes (LEDs) are predominantly used today. Blue LED light-curing units are more efficient, portable, and more durable than the systems noted previously. 8. Polymerization Shrinkage (C-factor) Composite materials shrink while polymerizing. This is referred to as The C-factor is the ratio of bonded surfaces to the unbonded, or free, polymerization shrinkage.(volume change) surfaces in a tooth preparation. Associated with a material pulling away from the preparation walls that may The higher the C-factor, the greater is the potential for bond disruption cause a gap at tooth restoration interface IF from polymerization effects. Polymerization shrinkage of the composite ˃ bond strength of the A Class IV restoration (one bonded surface and four unbonded composite to the dentin surfaces) with a C-factor of 0.25 is at low risk for adverse This can be controlled through: polymerization shrinkage effects. 1. Appropriate use of adhesive. A Class I restoration with a C-factor of 5 (five bonded surfaces, one 2. The amount of inserted composite (increment thickness). unbonded surface) is at much higher risk of bond disruption associated with polymerization shrinkage, particularly along the pulpal floor 3. Increment configuration (direction of insretion).  Internal stresses can be reduced in restorations subject to potentially high disruptive shrinkage forces (e.g., Class I preparations with a high C-factor) by using: (1)Oblique incremental additions to reduce the effects of polymerization shrinkage. (2)Use stress-breaking liner such as a filled dentinal adhesive, flowable composite, or RMGI. V. Advantages/ Disadvantages Advantages: Disadvantages: compared with amalgam restorations. Composite restorations are: According to potential gap formation and procedural difficulties. 1. Bonded to tooth structure, resulting in good retention, relatively 1. May have a gap formation, usually occurring on root surfaces low microleakage, minimal interfacial staining, and increased when strength of remaining tooth structure (resistance).  the forces of polymerization shrinkage of the composite material ˃ 2. Esthetic. the initial early bond strength of the material to dentin or 3. Conservative in tooth structure removal (less extension, uniform  from improper insertion of the composite by the clinician. depth not necessary, mechanical retention usually not necessary). 2. Technique sensitive compared with amalgam restorations as they 4. Insulating; having low thermal conductivity. are more difficult, time-consuming, and costly. 5. Used almost universally. 6. Repairable ( accepts addition). 3. Are more technique-sensitive because the operating site must be appropriately isolated, and proper bonding technique is mandatory on the tooth structure (enamel and dentin). 4. May exhibit greater occlusal wear in areas of high occlusal stress or when all of the tooth’s occlusal contacts are on the composite VI. Indications/ Contraindications material.  Indications 1. Direct restorations: Class I, II, III, IV, V, and VI restorations Contraindications: 2. Foundations or core buildups 1. If the operating site cannot be isolated from contamination by 3. Sealants and preventive resin restorations PRR. oral fluids. 4. Esthetic enhancement procedures: 2. If all of the occlusion is on the restorative material, direct composite may not be the right choice.  Partial veneers 3. composite restoration extensions on the root surface may exhibit  Full veneers gap formation at the junction of the composite and the root.  Tooth contour modifications So, RMGI restoration is the restoration of choice.  Diastema closures 5. Periodontal splinting VII. Clinical Technique 1. Local Anesthesia I. Local Anesthesia. II. Preparation of operating site. Profound anesthesia contributes to: III. Shade selection & confirmation. 1. More comfortable procedure. IV. Pre-operative assessment of occlusion. 2. Uninterrupted procedure. V. Isolation. 3. Marked reduction in salivation. VI. Bonding. VII. Incremental packing VIII. Finishing and polishing 2. Preparation of the Operating Site 3. Shade Selection Prior to beginning any composite restoration, it may be necessary to clean the operating site to remove plaque, pellicle, superficial stains 1. When? and calculus to create a site more receptive to bonding. The shade of the tooth should be determined before teeth are Prophy pastes containing flavoring agents, glycerin, or fluorides subjected to any prolonged drying because dehydrated teeth become may act as contaminants and should be avoided to prevent a lighter in shade as a result of a decrease in translucency. possible conflict with the acid-etch technique If bleaching (whitening) of teeth is contemplated, it should be done before any restorations are placed (2 weeks prior to restoration). Attributes of Color Tooth with high value looks More alive. While teeth with low value looks grey and non-vital. Hue Chroma Value 2. Lightening 3. Shade guide:  Most manufacturers provide shade guides for their specific materials, Good lighting is necessary for effective color selection. which usually are not interchangeable with materials from other Natural light is preferred for selection of shades. manufacturers. If no windows are present in the operatory to provide natural Most manufacturers also cross-reference their shades with those of the Vita daylight so, Classical shade guide a universally adopted shade guide. Color corrected operating lights or ceiling lights should be Because of the current popularity of bleaching, many manufacturers also offer composites in very light shades. available to facilitate accurate shade selection. If the dental operating light is used, it should be moved away to decrease the intensity, allowing the effect of shadows to be seen. Shade Selection Shade Selection Hue / Chroma Essential Shades Chroma 1 → 4 1 →4 1 →4 2 →4 Common Occasional Rare Ugly Hue → A B C D Reddish Brown Yellow Grey Grey Essential Shades Selection (rearrangement of 4. Different Composite Translucencies shades according to value) Also, most composite materials are available in enamel and dentin shades and translucent and opaque shades. Enamel shades are more translucent and typically are indicated for restoration of translucent areas such as incisal edges. Enamel Translucent Body Dentin © 3M 2004  5. Selection technique Shade guide is held near the tooth. The selection should be made as rapidly as possible to avoid eye fatigue, as the color receptors in the eye make it increasingly difficult to distinguish between similar colors after approximately 30 seconds. If more time is needed, the operator should rest the eyes by looking at a blue or violet object for a few seconds. These are the complementary colors of orange and yellow, which are the predominant colors in teeth. This causes the color receptors in the operator’s eye revitalized and re-sensitized. 5. Confirmation of selected shade. 4. pre-operative assessment of the occlusion Small amount of material of the selected shade can be placed directly should identify not only the occlusal contacts of the tooth or teeth to on the tooth, close to the area to be restored, and cured. be restored but also the occlusal contacts on adjacent teeth. This step may provide a more accurate assessment of the selected Knowing the pre-operative location of occlusal contacts is important shade. in planning the restoration outline form, establishing and correcting the proper occlusal contact on the restoration using articulating paper. 5. Isolation of the operative field: Isolation for tooth-colored restorations can be accomplished with a rubber dam or cotton rolls, with or without a retraction cord. Regardless of the method, isolation of the area is imperative if the desired bond is to be obtained. Contamination of etched enamel or dentin by saliva results in a significantly decreased bond; likewise, Contamination of the composite material during insertion results in degradation of physical properties. Polishing rubber cups different shapes and abrasiveness Finishing stones different shapes Polishing diamond paste and rubber brush  Operative dentistry I Introduction to dental amalgam AMALGAM RESTORATION AND MANIPULATION I Dr.Luluah K. Alhagas Assistant professor in operative dentistry department 2024 1. Ease of use. 1- Non-esthetic. Defined as a metallic restorative material 2-Less conservative (more removal of tooth structure composed of a mixture of silver–tin– 2. High strength. during tooth preparation). copper alloy and mercury. 3. Excellent wear resistance. 3-Non insulating. The unset mixture is pressed 4. Favorable long-term clinical research results. 4-More difficult tooth preparation. (condensed) into a specifically prepared tooth cavity and contoured to restore the 5. Low cost. 5- Environmental concern. tooth’s form and function. 1- used in posterior teeth 1- not used in esthetic areas (anterior teeth). restorations. 2- not used for mercury sensitive Dental amalgam classification 2- used in large cavities. patients. 3-used in areas with limited 3-not used in small cavities. moisture control. 4- not used if composite restoration will 4- core build up for crowns. offer a better conservative restoration. Requires less condensation. Amalgam classification Spherical Easy in carving. Gives improper proximal contact. alloy Used in class I cavity. Lathe-cut Requires more condensation. Difficult in carving. According to According to According to alloy Gives proper proximal contact. Used in class II cavity. particle shape copper content zinc content Admix alloy Has the advantages of spherical and lathe-cut alloy.  Low copper alloy Zinc containing alloy Less than 6% Cu More than 0.01% Zn High copper alloy Zinc free alloy More than 12% Cu 0.01% or less Zn Silver ( Ag) Increase strength and expansion Increase tarnish and corrosion resistance Dental amalgam composition Tin ( Sn) Decrease strength and expansion Increase flow and creep Copper ( Cu) Increase strength Increase tarnish and corrosion resistance Zinc ( Zn) Prevent oxidization of other metal in the alloy Increase strength, and creep resistance Dental amalgam setting reaction Low copper amalgam ( conventional ) High copper amalgam AgSn + Hg  AgSn + AgHg + SnHg AgSn + Ag-Cu + Hg  AgSg + AgHg + SnHg + Ag-Cu   1 2  eutectic  1 2 eutectic silver-tin silver-tin silver-mercury tin-mercury silver-tin Silver-copper silver-tin silver-mercury tin-mercury Silver-copper Ag-Cu + SnHg  AgHg + CuSn  Unreacted gammma  Unreacted gamma eutectic 2 1  1 Gamma 1 ( strongest phase) 1 Gamma 1 ( strongest phase) 2 Gamma 2 ( weakest phase) Silver-copper tin-mercury silver-mercury Copper-tin Eutectic 2 Gamma 2 ( weakest phase)  Eta  Dental amalgam properties Dental amalgam properties Creep Tarnish Compressive Tensile Modulus of Dimensional & & strength strength elasticity changes flow corrosion Dental amalgam properties Dental amalgam properties 1- Compressive strength: 2- Tensile strength: Is the ability of the material to withstand force lateral Is the ability of material that can to an object. ( stretching) withstand force loaded toward an object. ( compression) Amalgam has low tensile strength range between 48- 60 Mpa after 7 days, it depends on the amalgam type. Amalgam has high compressive strength range between 300-500 Mpa after 7 days, Low copper amalgam has lowest tensile strength. it depends on the amalgam type. High early tensile strength within the first 15 minuts Low copper amalgam has lowest can resist the fracture. compressive strength. High copper amalgam has the highest early tensile Amalgam is weak under tensile and shear strength. force. Factors affecting the amalgam strength: Factors affecting the amalgam strength: 3-Trituration: 1- Temperature: Effect of trituration on strength, depends on: Amalgam loses 15% of its strength when temperature raises from root - Type of amalgam alloy. temperature to mouth temperature. - Trituration time. Amalgam loses 50% of its strength when temperature raises inside the - Speed of the amalgametor. mouth up to 60%. Ex: drinking hot beverage. * under- trituration or over-trituration will affect the amalgam strength even with high or low copper amalgam. 2- mercury content: High mercury content will decrease the strength up to 50% 4-condensation: Low mercury alloy is recommended. - lathe-cut alloy needs more condensation for higher compressive *if mercury is too low it will produce rough and pitted surface. strength. - Spherical alloy needs light condensation for higher compressive strength. Dental amalgam properties Dental amalgam properties 3- Modulus of elasticity: Dentin= 4- Creep & Flow: Its time dependant plastic deformation of a Defined as measurment of material 15-20 Gpa material under static load. elastic stiffness. Composite= Flow measured during amalgam setting. Creep measured after amalgam setting. Amalgam has modulus of elasticity 17-22 Gpa Creep will lead amalgam to flow to the margin and range between 20-50 Gpa. Amalgam = make it protruded out of the margin. High copper amalgam is stiffer than low copper amalgam 20-50 Gpa This amalgam maybe weakened by corrosion and causing ditching around the amalgam margin. Enamel= stiff High copper amalgam has lower creep than low copper amalgam. 50-80 Gpa  Factors affecting the amalgam creep: Dental amalgam properties 1- Amalgam composition: 5- Dimensional changes: Presence of 2 in low copper amalgam will It’s a property of a material that can changes its increase the creep. original shape and dimentions easily, under heat or chemical reaction. 2- Amalgam manipulation: Amalgam has high dimensional changes and In high copper amalgam, proper the Amalgam should not high coeffiecent of thermal expansion. condensation pressure and trituration time expand or contract will decrease the creep. The greatest dimentional changes in low copper more than 20 m/cm amalgam 19.7 m/cm. at 37 ℃ Which is equal to 0.1- 0.4 % Dental amalgam properties Dental amalgam properties Mechanism of Dimensional changes: Delayed expansion : When mercury is combined with If zinc containing alloy contaminated with moistur amalgam alloy during its manipulation in a cavity prepration. It will undergo 3 dimensional changes. Will lead to gradual expansion of the amalgam after 1- initial contraction 3-5 days of setting and continue for months. Occurs for 20 minutes And will reduce amalgam strength. Contraction is up to 4.5 m/cm. This issue will cause: 2- expansion post operative sensitivty 3- limited delayed contraction occlusal interference Expansion over margin This expansion may reach to 400 m/cm Factors affecting the amalgam Dental amalgam properties dimensional changes : 6- Tarnish & Corrosion: 1- Mercury content: Tarnish: High mercury will give high expantion of amalgam restoration. Is the process by which a metal surface is discolored due to reaction to other 2- Trituration: chemicals ( sulfide, oxide, chloride,…), or Under-trituration, will lead to amalgam expansion. poor oral hygiene, or acidic food. Over-trituration, will lead to amalgam contraction. Amalgam surface appear dull or loss its 3- Condensation: luster Less condensation pressure, will lead to amalgam If tarnish continued, it will produce expansion. corrossion. Dental amalgam properties Excessive corrosion can lead to: 6- Tarnish & Corrosion: Increase porosity Corrosion: Is the chemical or electrochemical process by which a metal surface is partially or Reduce marginal integrity completely dissoluted due to environmental attack. Loss of strength Amalgam surface appear deteriorated If corrosion continued, it will produce Release metalic producets mechanical failure. in the oral environment Does amalgam have self sealing ability ? Dental amalgam properties Summary High copper alloy Low copper alloy Compressive strength High compressive strength Low compressive strength Tensile strength Low tensile strength Lowest tensile strength Modulus of elasticity Stiff Less stiff Creep & Flow Less creep & Flow More Creep & Flow Dimentional changes Low dimentional changes High dimentional changes ( more dimentional stability) ( Less dimentional stability) Tarnish & Corrosion Less Tarnish & Corrosion More Tarnish & Corrosion Medical/ dental history Dental amalgam cavity preparation Taking Pre- Chief radiographs operative complaint of the ( OPG,BW,..) patient Assessment Dental screening  General requirements: Cavity principles: 1- remove defects ( caries, defective restoration,… ). 2- prepration extension on sound enamel. 1-Initial 3- establish 90º cavosurface margin. 3- 4-Primary 5-Primary 6- tooth 2-Outline Cavosurface retention resistance Convenience preparation form. margin. form. form. form. depth. 4- minimum thickness 1.5-2 mm. 5- prepare undercut form. 6- incorporates any additional preparation features (grooves, slots, pins, cove) 1-Initial tooth preparation depth: 1-Initial tooth preparation depth: pulpal floor depth Axial wall depth Central grove DEJ 2-Outline form/ Cavosurface margin: 3- Retention form: It Prevents dislodgment of restoration along the path of insertion. primary 3- Retention form: 4- Resistance form: secondary It Prevents dislodgment of restoration if force applied in apical or oblique direction. Auxiliary means: Lock. Primary: Coves. 1- preserving cusps and marginal ridges. 2-having pulpal and gingival walls prepared perpendicular to Pins. the occlusal forces. Slots 3-having rounded internal preparation angles. 4-removing unsupported or weakened tooth structure.  4- Resistance form: 5- Convenience form: secondary Described as features that make the procedure Auxiliary means: easier or the area more accessible. Lock. Coves. Extension of outline form for caries removal, Pins. matrix placement, amalgam insertion,… Slots Extension of proximal margin to provide clearance from adjacent tooth. Alloy selection Finishing/ Proportion Dental amalgam manipulation polishing of the restoration of alloy Carving of Trituration the restoration of alloy Burnishing Condensation of the of amalgam restoration mix Alloy selection: Alloy proportion: The amount of mercury needed to coat all alloy It depends on the case particles, to produce homogenous amalgam mixture. Ratio of Alloy/Mercury equel to 1:1 1- particles shape. 2- copper content. 3- zinc content. Less mercury Some uncoated particles Dry/friable amalgam mix More Pitting/rough surface Excess mercury Excess 2 Less strength More creep & flow Trituration proportion: Under-trituration Over-trituration under mixing, leading the mixure over mixing, leading the mixure Mixing of mercury and alloy particles to produce to leave some particle uncoated to have high early strength, and coherent, plastic and and homogenous mass of by mercury. fast setting. condensable amalgam. mixture will look dull,and fraible. mixure will look shiny, and hard.  Amalgam carrier Condensation of amalgam mix: 1- Increase adaptation. 2- Allow excess mercury to reach the surface. 3- Increase amalgam density. 4- Increase final strength. Why we need to overfill the cavity 1 mm? Burnishing of amalgam restoration: Carving of amalgam restoration: 1- remove mercurry excess from the surface. 1- restore normal anatomy and contour. 2- guidline for amalgam carving. 2-increase adaptation at restoration margin. 3-increase adaptation at restoration margin. What is the direction of burnishing? What is the direction of carving? Checking occlusion Checking margin A- FLASH MARGIN: explorer tip catch from tooth to amalgam. B- SUBMARGIN/DITCH: explorer tip catch from amalgam to tooth. C- OPEN MARGIN: explorer tip catch in both directions. Finishing/Polishing of amalgam restoration: 1- reduce plaque retention. 2-reduce tarnish and corrosion. Is it necessary to use coolant with handpiece during finishing? Dental amalgam safety precaution Glass Ionomer Restoration (1) By: Dr. Rehab Alwakeb Operative Dentistry Division A water based material which is formed as a product of an acid-base reaction between the basic calcium-fluoro-aluomino-silicate glass powder and an aqueous solution of polyacid.  The set cement is thus formed of un- reacted glass particles surrounded by silica hydrogel dispersed in an amorphous matrix of hydrated Ca and Al polysalts. This results in: 1. Decrease strength & Weakened restoration 2. Loss of translucency & Increased opacity (poor esthetics and liability to staining) 3. Leakage.  Metal Reinforced GICs: Disadvantages: 1- More shrinkage during setting (added polymerization ) than conventional GIC 2- Less F release. 3- the lower water and carboxylic acid contents reduces the ability of the cement to wet tooth substrate (less bonding) 4- HEMA monomer can cause pulpal inflammation. Clinical Application: 5- The temperature associated with polymerization is a draw 1- fissure sealant. back. 2- base (sandwich technique). 3- restoration. 6- Water uptake by HEMA can cause fracture of all- ceramic crowns when hybrid ionomer are used as core build up or luting cement.  Introduction "The day is shortly coming when we will engage in practicing preventive rather than reparative dentistry, when we will understand the etiology Dental Cariology and pathology of dental caries that will be able to compete its destruction effect by systemic medications" Dr.Doaa Alhelais GV BLACK Because all criteria of infectious disease can be applied: There is source of infection "bacteria". Host resistance plays a role. What is caries? Can be transmitted by media (saliva). multifactorial, transmissible, infectious oral disease of It is an infectious the teeth that result in localized dissolution & destruction of the calcified tissue. disease..Why?? If not treated well it will reoccur. Depend on virulence of the microorganism (threshold dose). There is incubation period for the microorganism. Can cause tissue damage. Etiology of Dental Caries: Cariogenic bacteria in the biofilm metabolize refined carbohydrates for energy and produce organic acid byproducts. Cariogenic These organic acids, if present in the biofilm ecosystem for extended periods, can bacteria lower the pH in the biofilm to below a critical level (5.5 for enamel, 6.2 for dentin). The low pH drives calcium and phosphate from the tooth to the biofilm in an PH PH Carbohydra attempt to reach equilibrium, hence resulting in a net loss of minerals by the tooth te and Demineralization. sugar pH in the biofilm returns to neutral and the concentration of soluble calcium and phosphate is supersaturated relative to that in the tooth, mineral can then be added back to partially demineralized enamel, in a process called Remineralization. The balance between demineralization and remineralization has been illustrated in terms of pathologic factors (factors for demineralization) and protective factors (factors for reminarlization) Understanding the balance between demineralization and remineralization is key to It is essential to understand that caries lesions, or cavitations in teeth, are signs of an underlying condition, an imbalance between protective caries management. and pathologic factors favoring the latter. What are these factors???  What makes this disease complicated that there are multiple factors that play a role in causing of the disease. Although symptomatic treatment is important, failure to identify and treat the underlying causative factors allows the disease to continue  Ecologic Factors of Dental Caries 1-The Role of the Biofilm Dental plaque is a term historically used to describe the soft, tenacious film accumulating on the surface of teeth. dental Dental plaque plaque used is a term historically hastobeen describemore the soft,recently referred tenacious film toonastheasurface accumulating plaque biofilm, of teeth. or simply biofilm. Biofilm is composed mostly of bacteria, their by-products, extracellular matrix, and water The accumulation of biofilm on teeth is a highly organized and ordered sequence of events. Free-floating organisms are cleared rapidly from the mouth by salivary flow and frequent swallowing. Many of the organisms found in the mouth are not found elsewhere Only a few specialized organisms, primarily streptococci, are able in nature. Free-floating organisms are cleared rapidly from the mouth by salivary flow and frequent swallowing. Only a few specialized Dental plaque is a term historically used to describe the soft, tenacious film accumulating on the surface of teeth. to primarily organisms, adhere to oralaresurfaces streptococci, such able to adhere to oralas thesuch surfaces mucosa andandtooth as the mucosa structure. tooth structure. Survival of microorganisms in the oral environment depends on their ability to adhere to oral surfaces such as the mucosa and tooth structure. The pits and fissures on the crown may harbor a relatively simple Ecologic Basis of Dental Caries population of streptococci, the root surface in the gingival sulcus may harbor a complex community dominated by filamentous and spiral 2-Tooth Habitats for Cariogenic Biofilm bacteria. Tooth habitats favorable for harboring pathogenic biofilm include (1)pits and fissures. (2)The smooth enamel surfaces immediately gingival to the proximal contacts. Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease (3)The Professional gingival tooth cleaningthird of the is intended facialbiofilm to control and lingual surfaces (plaque) and prevent of the clinical crown. disease (4)Root surfaces, particularly near the cervical line; and subgingival areas These sites correspond to the locations where caries lesions are most frequently found. Ecologic Basis of Dental Caries Ecologic Basis of Dental Caries Tooth Habitats for Cariogenic Biofilm 3-Saliva: Nature’s Anticaries Agent Saliva plays a key role as a natural anticaries agent : Salivary flow rate, salivary Buffering capacity. Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease Salivary protective mechanisms that maintain the normal oral flora Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease and tooth surface integrity include : 1. Bacterial clearance 2. Direct antibacterial activity 3. Buffers. 4. Remineralization  1. Bacterial clearance : 3. Buffers: The flushing effect of this salivary flow is, by itself, adequate to The buffering capacity of saliva is determined primarily by the remove virtually all microorganisms not adherent to an oral surface concentration of bicarbonate ion. The benefit of the buffering is to reduce the potential for acid formation. 2. Direct antibacterial activity : Salivary glands produce an impressive array of antimicrobial Products. Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease 4. Remineralization : Lysozyme, lactoperoxidase, lactoferrin, and agglutinins possess Saliva and biofilm fluid are supersaturated with calcium and phosphate antibacterial activity. ions. These protective proteins are present continuously at relatively This supersaturated state of the saliva provides a constant opportunity for uniform levels, have a broad spectrum of activity. remineralizing enamel Ecologic Basis of Dental Caries Ecologic Basis of Dental Caries 4-Oral Hygiene and Its Role in the Caries Process Individuals with decreased salivary production (owing to illness, Oral hygiene including proper tooth brushing and flossing, is medication, or irradiation) may have significantly higher caries another ecologic determinant of caries onset and activity. susceptibility Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease The cleaning process does not destroy most of the oral bacteria Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease but merely removes them from the surfaces of teeth. Careful mechanical cleaning of teeth disrupts the biofilm and leaves a clean enamel surface. Ecologic Basis of Dental Caries Ecologic Basis of Dental Caries 4- Diet and caries 4- Diet and caries High-frequency exposure of fermentable carbohydrates such as sucrose may be the most important factor in producing cariogenic biofilm. Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease when ingestion of fermentable carbohydrates is severely restricted or absent, biofilm growth typically does not lead to caries. Ecologic Basis of Dental Caries Ecologic Basis of Dental Caries Professional tooth cleaning is intended to control biofilm (plaque) and prevent disease  Ecologic Basis of Dental Caries Clinical charactrestics of carious lesion The caries lesion is the product of disequilibrium between the demineralization and every time you eat something, the pH drops below the critical point of 5.5. remineralization processes discussed previously. It takes 30-40 minutes for your saliva to get you back to the safe zone. When the tooth surface becomes cavitated, a more retentive surface area becomes available The longer you snack for, the longer you are at risk and the longer it takes for your mouth to recover. to the biofilm community. This situation results in a rapid and progressive destruction of the tooth structure. When enamel caries penetrates to the dentinoenamel junction (DEJ), rapid lateral expansion of the caries lesion occurs because dentin is much less resistant to acid demineralization. This sheltered, highly acidic, and anaerobic environment provides an ideal niche for cariogenic bacteria. A) Pits and fissures of enamel: Clinical Sites for Caries Initiation Bacteria rapidly colonize the pits and fissures of newly erupted teeth. There are three distinctly different clinical sites for caries initiation with different S. sanguis, are found in the pits and fissures of newly erupted teeth, whereas large numbers of Mutanus Streptocci usually are found in carious pits and fissures. shapes of lesion: The shape of the pits and fissures contributes to their high susceptibility to caries: A) Pits and fissures of enamel (most susceptible area) The long, narrow fissure prevents adequate biofilm removal B) Smooth enamel surfaces that shelter cariogenic biofilm; C) The root surface A) Pits and fissures of enamel: A) Pits and fissures of enamel: Pit-and-fissure caries expands as it penetrates into the enamel. Pit-and-fissure caries expands as it penetrates into the enamel. The entry site may appear much smaller than the actual lesion, making clinical diagnosis difficult. The entry site may appear much smaller than the actual lesion, making clinical diagnosis difficult. A) Pits and fissures of enamel: B) smooth enamel surfaces In cross-section, the gross appearance of a pit-and-fissure lesion is A conical lesion with the base towards the DEJ. The smooth enamel surfaces of teeth present a less favorable site for cariogenic biofilm It is an inverted “V” with a narrow entrance and a progressively wider area of attachment. involvement closer to the DEJ. Cariogenic biofilm usually develops only on the smooth surfaces that are near the gingiva or are under proximal contacts.  C) Root surface caries: B) smooth enamel surfaces The root surface is rougher than enamel and readily allows cariogenic biofilm formation A cross-section of the enamel portion of a smooth-surface lesion shows a V-shape, with in the absence of good oral hygiene. a wide area of origin and the apex of the V directed toward the DEJ. The cementum covering the root surface is extremely thin and provides little resistance A conical lesion with the apex towards the DEJ. to caries attack. Root caries lesions have less well-defined margins, tend to be U-shaped in cross- section, and progress more rapidly because of the lack of protection from an enamel covering. Progression of Enamel caries Progression of Enamel caries The time for progression from non-cavitated enamel caries to clinical caries (cavitation) on smooth surfaces is estimated to be 18 months ± 6 months. A more advanced lesion develops a rough surface that is softer than the unaffected, normal enamel. Softened chalky enamel that can be chipped away with an explorer is a sign of active caries. Progression of Enamel caries The supersaturation of saliva with calcium and phosphate ions with The presence of trace amounts D) Progression of Enamel caries of fluoride ions serves as the driving force for the remineralization process. These discolored, remineralized, arrested caries areas are intact and Remineralized (arrested caries) lesions can be observed clinically as are more resistant to subsequent caries attack. intact, but discolored,usually brown or black, spots. They should not be restored unless they are esthetically unacceptable. These discolored, remineralized, arrested caries areas are intact and are more resistant to subsequent caries attack. They should not be restored unless they are esthetically unacceptable. Classification of Dental Caries 1- Enamel Caries: On clean, dry teeth, the earliest evidence of caries on the smooth enamel surface of a crown is a white spot.(chalky white, opaque areas ) These lesions usually are observed on the facial and lingual surfaces of teeth. Revealed only when the tooth surface is desiccated or dried. They termed non cavitated enamel caries lesions. These areas of enamel lose their translucency because of the extensive subsurface porosity caused by demineralization  Microscopic Features of Non cavitated Enamel s: Microscopic Features of Non cavitated Enamel : there are 4 zones identified pre-cavitation. These are: 1.Translucent zone – the advancing edge of the lesion 2.Dark zone 3.Body of the lesion 4.Surface zone Microscopic Features of Non cavitated Enamel 2- Dentin Caries: 1) Translucent Zone This is the advancing edge of the enamel lesion. Dentin contains much less mineral and possesses microscopic tubules that provide a pathway for the It is only present in 50% of lesions. ingress of bacteria and egress of mineral 2) Dark Zone Once bacteria penetrate enamel, they spread laterally along DEJ and attack dentin over a wide area. Lies adjacent and superficial to the translucent zone. Present in up to 95% of lesions. (Called positive zone as it is always present) Dentinal caries is V-shaped in cross-section with a wide base at the DEJ and the apex directed pulpally. 3) Body of the lesion Caries advances more rapidly in dentin than in enamel because dentin provides The largest part of the lesion and lies between the surface zone and dark zone. much less resistance to acid attack owing to less mineralized content. Area of greatest demineralization The infected lesion of dentin is helped in its course by the 4) Surface Zone presence of tubules within dentin which provide an easy pathway This zone appears almost unaffected in the superficial layers to the bacteria. Minimal demineralisation also REMAINS MORE HEAVILY MINERALIZED because of Ca , P and Floride. Microscopic Features of Non cavitated Dentin : Microscopic Features of Non cavitated Dentin : Three different zones have been described in carious dentin.The zones are most clearly distinguished in slowly advancing lesions. ZONE 1: NORMAL DENTIN The deepest area is normal dentin, which has tubules with odontoblastic processes that are smooth No bacteria are present in the tubules Microscopic Features of Non cavitated Dentin : Three different zones have been described in carious dentin.The zones are most clearly ZONE 3: INFECTED DENTIN distinguished in slowly advancing lesions. Also called outer carious dentin, this is the outermost carious layer, the layer that the clinician would encounter first when opening a lesion. ZONE 2: AFFECTED DENTIN The infected dentin is the zone of bacterial invasion and is marked by widening and Also called inner carious dentin, affected dentin is a zone of demineralization of intertubular distortion of the dentinal tubules, which are filled with bacteria dentin Can be remineralizes affected dentin zone can also be subclassified to 3 subzones: (1) subtransparent dentin (2) transparent dentin (3) turbid dentin.  2- Dentin Caries: How to discriminate between different dentine layers? The pulp–dentin complex reacts to caries attacks by attempting to initiate remineralization and blocking off the open tubules. Clinical Infected Affected Sound method Three levels of dentinal reaction to caries can be recognized: Visual Paler light Yellowish/ inspection Dark brown brown white (1) Reaction to a long-term, low-level acid demineralization associated with a slowly advancing lesion. Tissue Wet/ soft Sticky/ Hard (2) Reaction to a moderate-intensity attack. hardness scratchy (3) Reaction to severe, rapidly advancing caries characterized by very high acid levels. Caries Dark Red Pale red Pink disclosing dyes 2- Dentin Caries: 2- Dentin Caries: In slowly advancing caries: In slowly advancing caries: Dentin can react defensively (by repair) to low-intensity and moderate-intensity caries attacks as long as the pulp remains vital and has an adequate blood circulation. Dentin that has more mineral content than normal dentin is termed sclerotic dentin Sclerotic dentin is usually shiny and darker in color but feels hard to the explorer tip. This repair occurs only if the tooth pulp is vital. The apparent function of sclerotic dentin is to wall off a lesion by blocking (sealing) the tubules. The permeability of sclerotic dentin is greatly reduced compared with In slowly advancing caries, a vital pulp can repair demineralized dentin by remineralization of the intertubular dentin and by apposition of peritubular dentin. normal dentin because of the decrease in the tubule lumen diameter 2- Dentin Caries: 2- Dentin Caries: More intense caries activity results in bacterial invasion of dentin. Infected dentin contains a wide variety of pathogenic materials or irritants, including high acid levels, hydrolytic enzymes, bacteria, and bacterial cellular debris. These materials can cause the degeneration and death of odontoblasts and their tubular The third level of dentinal response is to severe irritation, Acute, rapidly extensions below the lesion and a mild inflammation of the pulp happen. advancing caries with high levels of acid production overpowers dentinal defenses and results in infection, abscess, and death of the pulp. The pulp may be irritated sufficiently from high acid levels or bacterial enzyme production to cause the formation (from undifferentiated mesenchymal cells) of replacement odontoblasts (secondary od