Lecture 5 Composite Restoration Part (2) PDF

Composite restoration (2) By: Dr. Rehab Alwakeb Operative Dentistry Division Reference: Art and science of operative dentistry 6th edition. “Introduction to Composite Restorations , chapter 8, p:216.” ILOs: I. Determine advantages, disadvantages, indications, and contraindications of...

Composite restoration (2) By: Dr. Rehab Alwakeb Operative Dentistry Division Reference: Art and science of operative dentistry 6th edition. “Introduction to Composite Restorations , chapter 8, p:216.” ILOs: I. Determine advantages, disadvantages, indications, and contraindications of composite restoration II. Determine the clinical technique of composite application. IV. Properties (continuation)  7. polymerization: It is a chemical reaction where low molecular weight monomer molecules are converted to high molecular weight polymer chains. The two polymerization methods are (1)the self-cured method (2)the light-cured method using visible light.  Lightsource Light curing specificwavelength Diketone initiators such as camphoroquinone photo-initiator. It is activated by wavelengths in the range of 370-500 nm with the peak at 468 nm (blue region of the visible spectrum). It dissociate into radicals upon irradiation. 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 Composite materials shrink while polymerizing. This is referred to as polymerization shrinkage.(volume change) Associated with a material pulling away from the preparation walls that may cause a gap at tooth restoration interface IF man Polymerization shrinkage of the composite ˃ bond strength of the than composite to the dentin Debonding This can be controlled through: 1. Appropriate use of adhesive. 2. The amount of inserted composite (increment thickness). 3. Increment configuration (direction of insretion). 4 Canbeused as a stressbearingLiner cushion  (C-factor) The C-factor is the ratio of bonded surfaces to the unbonded, or free, surfaces in a tooth preparation. mp The higher the C-factor, the greater is the potential for bond disruption from polymerization effects. A Class IV restoration (one bonded surface and four unbonded surfaces) with a C-factor of 0.25 is at low risk for adverse polymerization shrinkage effects. Bigger A Class I restoration with a C-factor of 5 (five bonded surfaces, one unbonded surface) is at much higher risk of bond disruption associated with polymerization shrinkage, particularly along the pulpal floor C factor stresses Cfactor by incrementation EEE all surfaces Q Bestconfiguration Oblique  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: imp compared with amalgam restorations. Composite restorations are: 1. Bonded to tooth structure, resulting in good retention, relatively low microleakage, minimal interfacial staining, and increased strength of remaining tooth structure (resistance). 2. Esthetic. 3. Conservative in tooth structure removal (less extension, uniform depth not necessary, mechanical retention usually not necessary). 4. Insulating; having low thermal conductivity. 5. Used almost universally. 6. Repairable ( accepts addition). Unlikeamalgam Disadvantages: According to potential gap formation and procedural difficulties. 1. May have a gap formation, usually occurring on root surfaces when  the forces of polymerization shrinkage of the composite material ˃ the initial early bond strength of the material to dentin or  from improper insertion of the composite by the clinician. 2. Technique sensitive compared with amalgam restorations as they are more difficult, time-consuming, and costly. 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 material. VI. Indications/ Contraindications Indications mostlyeverything101 1. Direct restorations: Class I, II, III, IV, V, and VI restorations 2. Foundations or core buildups 3. Sealants and preventive resin restorations PRR. 4. Esthetic enhancement procedures:  Partial veneers  Full veneers  Tooth contour modifications  Diastema closures 5. Periodontal splinting  imp Contraindications: 1. If the operating site cannot be isolated from contamination by oral fluids. 2. If all of the occlusion is on the restorative material, direct composite may not be the right choice. 3. composite restoration extensions on the root surface may exhibit gap formation at the junction of the composite and the root. So, RMGI restoration is the restoration of choice. Indirect Q whenis VII. Clinical Technique theproper time shade selection I. Local Anesthesia. II. Preparation of operating site. Apl Beforerubber Dam isolation III. Shade selection & confirmation. IV. Pre-operative assessment of occlusion. V. Isolation. be whenthe VI. Bonding. this VII. Incremental packing Dry the shade VIII. Finishing and polishing can vary 1. Local Anesthesia Profound anesthesia contributes to: 1. More comfortable procedure. 2. Uninterrupted procedure. 3. Marked reduction in salivation.  2. Preparation of the Operating Site Prior to beginning any composite restoration, it may be necessary to clean the operating site to remove plaque, pellicle, superficial stains and calculus to create a site more receptive to bonding. Prophy pastes containing flavoring agents, glycerin, or fluorides may act as contaminants and should be avoided to prevent a possible conflict with the acid-etch technique  3. Shade Selection 1. When? The shade of the tooth should be determined before teeth are subjected to any prolonged drying because dehydrated teeth become lighter in shade as a result of a decrease in translucency. If bleaching (whitening) of teeth is contemplated, it should be done before any restorations are placed (2 weeks prior to restoration). Attributes of Color Hue Chroma Value Saturation Brightness High value more natural  Tooth with high value looks More alive. While teeth with low value looks grey and non-vital. 2. Lightening Good lighting is necessary for effective color selection. Natural light is preferred for selection of shades. If no windows are present in the operatory to provide natural daylight so, Color corrected operating lights or ceiling lights should be 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. 3. Shade guide:  Most manufacturers provide shade guides for their specific materials, which usually are not interchangeable with materials from other manufacturers. Most manufacturers also cross-reference their shades with those of the Vita Classical shade guide a universally adopted shade guide. Because of the current popularity of bleaching, many manufacturers also offer composites in very light shades.  Shade Selection Hue / Chroma Chroma 1 → 4 1 →4 1 →4 2 →4 Hue → A B C D Reddish Brown Yellow Grey Grey  Shade Selection Essential Shades Common Occasional Rare Ugly Essential Shades Selection (rearrangement of shades according to value) most common  4. Different Composite Translucencies 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 incisal 49m © 3M 2004 Anterior 5. Selection technique rip 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. Small amount of material of the selected shade can be placed directly on the tooth, close to the area to be restored, and cured. This step may provide a more accurate assessment of the selected shade. 4. pre-operative assessment of the occlusion should identify not only the occlusal contacts of the tooth or teeth to be restored but also the occlusal contacts on adjacent teeth. Knowing the pre-operative location of occlusal contacts is important in planning the restoration outline form, establishing and correcting the proper occlusal contact on the restoration using articulating paper. articulate 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. O  Polishing rubber cups different shapes and abrasiveness Finishing stones different shapes Polishing diamond paste and rubber brush Thank You