Selection of Restoration PDF

SELECTION OF A SUITABLE RESTORATIVE MATERIAL By/ Amira Samy ◦The practice of clinical dentistry depends not only on a complete understanding of the various clinical techniques but also on an appreciation of the fundamental biological, chemical and physical principles that support the c...

SELECTION OF A SUITABLE RESTORATIVE MATERIAL By/ Amira Samy ◦The practice of clinical dentistry depends not only on a complete understanding of the various clinical techniques but also on an appreciation of the fundamental biological, chemical and physical principles that support the clinical applications. ◦Successful results in operative dentistry cannot be achieved without using proper restorative materials. ◦The final restoration will never be better than the properties of the material selected for its fabrication Requirements for an ideal restoration: 1. Adaptability to cavity walls and margins 2. Great strength properties (sustain the normal physiologic occlusal load). 3. Dimensional stability in the cavity 4. Biologic compatibility with the adjacent structures and pulp (Protect and maintain pulp vitality). 5. Insolubility in the fluids of the mouth 6. Harmonious color (Restore normal esthetics). 7. Low thermal conductivity and thermal changes 8. Convenience of manipulation. 9. Stop the progress of the lesion. 10. Restore normal function. 11. Restore any speech defects. 12. Restore and maintain the integrity of the dental arch. 1- Adaptability To Cavity Walls And Margins: This refers to the degree of proximity to cavity walls and margins that the restorative material will be able to attain and maintain under oral conditions. 2- Great Strength Properties The restorative material must have adequate strength against all the types of functional stresses including tensile, compressive, shear and impact, whether these be static or dynamic. 3- Dimensional stability in the cavity: The restoration must exhibit no dimensional changes in the form of EXPANSION or CONTRACTION after being placed in the cavity whether during setting or due to thermal changes in the mouth. ◦If it expands, it may overhang producing premature contact, which may fracture due to stress concentration. ◦On the other hand, contraction or shrinkage of the restoration inside its cavity may cause marginal leakage with subsequent troubles or it may lead to its looseness and displacement. 4-Biologic Compatibility With the Adjacent Structures and Pulp: Biocompatibility: refers to how well the material coexists with the biological equilibrium of the tooth. Restorative material must be free from noxious effects on the gingival tissues and the pulp. Factors that affect the biologic reaction of the restoration: Pulp condition. Thickness of dentin bridge. Reparative power of the pulp. Chemical make up of the R.M.. Restorative technique. Behavior of the restoration inside the oral cavity. 5-Insolubility In The Fluids Of The Mouth: The restorative material must be perfectly insoluble and indestructible in the fluids of the mouth irrespective of its type and pH fluctuations. 6-Harmonious Color: To stimulate the color of the tooth, the restorative material is required to have the combined color of enamel and dentin. 7- No conductivity to thermal changes: The restoration may be subjected, even temporarily, to wide ranges of temperature changes. Therefore, it should be non-conductor of heat. 8- Convenience of manipulation: The restorative material must be easy to fabricate without detailed procedures or expensive special equipment. The restorative material should not be sensitive to the human variables of the operator. 9-Stop the progress of the lesion: It should stop further progress of the present lesion such as caries, erosion, abrasion, attrition or fracture. If the restoration doesn't maintain a proper seal, it will not stop further progress of the lesion. 10-Restore normal function: The restored tooth must be functioning normally. 11. Restore any speech defects: It should restore any speech defects due to missing parts of the hard tooth structures (diastema or chipping). 12. Restore and maintain the integrity of the dental arch and periodontium: Proper restorations must have proper anatomy, contact and contouring. With no overhanging. According to the previously enumerated requirements, still none of the available restorative material is ideal. For this reason, we have to compromise and select the most suitable material for a particular case.  Types of restorative materials Restorative materials Permanent Temporary Non- Metallic Metallic  Direct Restorations Restorative materials that are applied to the tooth while the material is pliable and able to carve and finish. Example: Amalgam Composite resins Glass ionomer Intermediate restorative materials  Amalgam Is an affordable and durable material that is used predominantly to restore premolars and molars. ◦ Issues Concerning Amalgam: * Harm to patients: Essentially harmless, the exception is with patients who have many amalgam restorations, or a high sensitivity to metals. * Harm to Dental Personnel: Health concerns with high exposure to mercury, not amalgam. (Tremors, Kidney dysfunction, Depression, Nervous system disorders). Due to the known toxicity of the element mercury and environmental pollution, plus the availability of alternative materials , there is some controversy about the use of amalgam.  Advantages 1- Superior adaptation to cavity walls, which uniquely improves on aging. ↓↓↓ micro leakage → ↓ Postoperative hypersensitivity and Recurrent caries. 2- High compressive strength. → sustain occlusal forces without fracture 3- Adequate form stability due to : a. Insolubility b. High wear resistance c. Low creep value (in modern amalgam alloys). → The restoration maintain surface polish, occlusal anatomy and interproximal contact. 4- Low coefficient of thermal expansion → decreases the marginal leakage by reducing the marginal percolation. 5- Ease of manipulation:→ easy technique for general practitioner to obtain a successful and lasting restoration. 6- Relative low cost due to the relatively short time for the construction of the restorations.→ the most popular restoration  Disadvantages Bad esthetics Requires mechanical retention in the cavity (Not adhesive). Environmental and occupational hazards Amalgam restorations conduct thermal and galvanic shocks to the pulp lead to pulp irritation. Permanent discoloration of both tooth and gingiva will be the expected failures after restoration of large cavity with amalgam. Indications for Using Amalgam: In individuals of all ages. Small and medium sized class I & II cavities where amalgam is not subjected to tensile loads. In stress-bearing areas of the mouth. As a foundation. When personal oral hygiene is poor. When moisture control is problematic. When cost is an overriding patient concern. Contraindications for using Amalgam: when esthetics is an important issue. Patient has a history of allergy to mercury or other amalgam components. Extensive lesions especially those including undermined cusps where cast gold serves better. Rampant caries where glass ionomer can act as a control restoration. Presence of opposing gold restorations to avoid galvanic activity There are some requirements for placing amalgam restoration: 90-degree cavo-surface angle (butt joint). Adequate depth. Adequate mechanical retention (Macro-mechanical). It can restore: Simple, compound and complex class I cavities. Simple, compound and complex class II cavities. Class III (distal surface of caniene). Class V. Failure of amalgam restoration: Very large carious tooth involving multiple surfaces. Improper cavity preparation which affects resistance and retention of amalgam. Delayed expansion in zinc containing amalgam. Inadequate pulp protection. Inadequate matrix application. Improper manipulation of material. Improper carved amalgam. Failure to polish decreases corrosion resistance Composite Resin (Bowen 1963): Composites composed of two phases: Matrix and Filler bound together by coupling agents. Advantages: Adhesive Esthetic Reasonable wear properties Micromechanical bond to enamel Minimal tooth preparation required Easily shaped to the anatomy of a tooth. Repairable Command set Issues Concerning resin composites: ✓ The volumetric contraction of polymeric resin and the relatively high- coefficient of thermal expansion can create leakage space at the restoration-tooth structure interface and stimulate bacterial irritation for the pulp. ✓ In addition to its monomer contents and the heat produced during polymerization that lead to chemical and thermal irritation to the pulp.  Disadvantages: Technique sensitive Expensive Time consuming Post-operative sensitivity Polymerization shrinkage (Marginal leakage). Hydrolytic instability. Questionable biocompatibility. Limited wear-resistance in high stress areas. More difficult, time consuming and costly (compared to amalgam). INDICATIONS OF COMPOSITES: ◦ Classes I , II ,III ,IV ,V ,VI restorations. ◦ Core build up. ◦ Sealant and conservative restorations. ◦ Esthetic enhancement procedures: ◦ Partial veneers. ◦ Full veneers. ◦ Tooth contour modifications. ◦ Diastma closures. Cavity preparation (Adhesive Cavity designs): ◦ it's characterized by having:- 1) Conservative outline with minimal extensions: Preservation of the tooth structure: The outline of the cavity is restricted to the extension of caries. The cavity includes the defective lesion only. 2) Rounded rather than squared lines and point angles: This is to conform to the wettability of the material. Resin composites are viscous in nature so require rounded walls to facilitate their adaptation. 3) Beveled cavo - surface angles: - It's performed to a 45° for a width of 0.5-1 mm in thickness provided it's not located in stress - bearing sites to avoid marginal chipping of resin composite. - It should not also be done in gingival seats, which end in dentin, cementum or thin enamel. Instead, a glass- ionomer liner is placed to enhance adaptation of the restoration. 4-Axial walls may be composed partially or completely of enamel, because no extension for retention in dentin is required. Failure in composite restorations: Incomplete removal of caries. Incomplete etching or removal of acid etch. Excess application of bonding agent. Lack of moisture control. Excessive dryness of dentin. Contamination of composite. Bulk placement. Improper polymerization method. Incomplete finishing and polishing. Failure with time Postoperative hypersensitivity. Discoloration. Fracture of margin. Loss of contact after period Glass ionomer cement: Developed in early 1970’s by Wilson and Kent who combined technology of zinc polycarboxylate and silicate cements. Earlier these were called as ‘alumino silicate polyacrylate’ (ASPA). Glass ionomer restorations are the best regarding biologic compatibility. This can be attributed to their chemical bond with the adjacent tooth structures, to their high molecular size of its acid contents, fluoride release, minimal setting expansion and preservative tooth preparation. Issues Concerning Glass-ionomer: ◦ Chemical adhesion with the surrounding hard tooth tissues or at least, it should maintain intimate adaptation with the surrounding cavity walls at the restoration- tooth structure interface (provide marginal sealing to prevent micro- leakage). ◦ First truly adhesive restorative materials. ◦ Release fluoride over time. ◦ Biomimetic- resembles dentin. Advantages: Chemical bonding to tooth structure. Biocompatible. Anti-cariogenic (Fluoride leaching). Less technique sensitive. Conservation of tooth structure (Minimal cavity preparation). Good marginal seal. Less dimensional changes compared to the other restorations. Modifications available for every specific purpose. Act as fluoride reservoir. Resin Modified Glass Ionomer Advantages: - Adhesive - Aesthetic - Command set - Simple to handle - Fluoride release.  Disadvantages: Brittle Susceptible to erosion and wear Low fracture resistance. Low wear resistance. Questionable esthetics due to opacity. Require moisture control during manipulation and placement. Reduced compressive strength. Water sorption (RMGI). Indications of GI: Restoration of permanent teeth: Class V, III and small class I. Root caries. Abrasion and erosion. Restoration of deciduous teeth. Luting cement. Preventive restoration: Tunnel preparation. Pits & fissure sealants. Material of choice for restoration of primary posteriors Small occlusal and inter proximal cavities in permanent teeth  Liner under composite. Core build up. Repair of external root resorption. Repair of perforation. ART. Sandwich technique. Metal modified as core build up. Contraindications: In stress bearing areas. In cuspal replacement cases. In cases which require aesthetics.  Factors influencing selection of the restorative materials I- Factors concerning the available restorative materials. II- Factors concerning the patient: a- Factors related to the general condition of the patient. b- Factors related to the oral cavity. c- Factors concerning the tooth to be restored. d- Factors related-to the cavity to be restored. III- Factors related to the operator. II- Factors concerning the patient: a. Patient’s age: 1. Young patients: * Cannot stand prolonged procedures * Cannot follow instructions * Prefer esthetic restoratives 2. Middle aged patient: * Prefers ideal restorations 3. Old patients: * Cannot withstand long operations * Prefer strong permanent restorations b. Patient’s gender: 1. Male patients: prefer strong permanent restorations. 2. Female patients: advocate esthetics. c. Patient’s occupation: 1. Regular patients: ask for restoration of reasonable price and prefer ideal restoration if possible. 2. Public personalities: like esthetic restorations as politicians, professors, teachers, movie stars, and artists. 3. Few technicians, butchers, fruit sellers, shoemakers and mechanics advocate gold color in esthetic areas.  d. Physical condition of the patient: 1. Fit patients: Stay on dental chair for the required time 2. Debilitated patients: Cannot tolerate long procedures. Prefer cast restorations. 3. Handicapped patients: Prefer short term restorations. e. Educational and social conditions of the patient: 1. Educated patient: the most suitable restoration 2. Less educated persons: prefer esthetic restoratives 3. Uneducated patients: agree with operator selection f. Mental condition of the patient: 1. Normal persons can easily be satisfied with the most suitable restoration according to the knowledge introduced by the dentist. 2. Psychic patients cannot withstand treatment for long time and prefer esthetic restorations. g. Patient's habits: 1. Patients with smoking habit suffer from stains and acidic saliva. 2. Alcoholics always suffer from solubility of dental cements. 3. Persons with bruxism need strong restorations with high surface hardness. i-Economic condition of the patient: 1. Wealthy persons: select the best restoration whatever it costs. 2. Ordinary people: should be informed about the expenses first. 3. Poor patients: prefer amalgam in posterior teeth composite for esthetic restoration.  Factors related to the condition of the oral cavity a. Oral hygiene: 1. Patients with good oral hygiene should be instructed to maintain this condition. Any restoration can be used. 2. Patients with poor oral hygiene should improve and maintain their mouths clean before the restorative procedures to decrease the acidity of saliva which may affect the success of the restoration. b. Caries incidence: 1. Patients with high caries incidence need full coverage restorations, otherwise, short-term regular check up is imp. to discover any progress of caries to be treated early. 2. Teeth with rampant caries are better to be treated with temporary restorations until the condition subside. C. Condition of occlusion: 1. Normal occlusion has no troubles in the selection of the suitable restorations. 2. Conditions of malocclusion such as cross bite, sever overlap, plunger cusp and tilted teeth need restorations of high strength. d. Presence of metallic restoration: 1. The present metallic restoration is leading for the selection of the future metallic restoratives. 2. Presence of different metallic restorations may cause tarnish and corrosion and/ or may cause pain due to galvanic shocks. 3. Non metallic restoration can be used with any type of metallic restoratives without any side effect. e. Position of the tooth: ◦ Anterior teeth: restored with esthetic R.M. such as castable ceramics, or resin composite. ◦ Smiling teeth: restored with esthetic materials few patients prefer gold color. ◦ Abutment teeth: restored with amalgam or composite restorations. However, those used with removable partial denture should be restored with cast gold restoration. ◦ Wisdom teeth: restored with zinc free amalgam or cast restorations. f. Form of the tooth: ◦ Hutchinson teeth or peg-shaped lateral incisors may be restored with full coverage restorations / composite restoration. ◦ Mulberry molars should be corrected occlusally with cast gold restorations or full coverage restorations. ◦ Normal teeth should be restored with the suitable restorative material. g. Condition of calcification: ◦ Hypocalcified tooth or teeth with friable enamel should be restored with strong restoration to protect their cavity margins (bioactive nano-filled composites). ◦ Posterior teeth indicate the use of cast metal (gold) restorations and contraindicate application of gold foil restorative material. d. Size and condition of the remaining coronal portion: ◦ In regular condition the remaining tooth structures of the crown can confine the restoration. ◦ If the remaining coronal portion cannot confine the restoration. …………………………………………………………………… e. Vitality of the pulp: 1- Teeth with hyperemia: should be restored with a suitable temporary R.M. until the irritational condition is relieved and then restored permanently with a suitable restoration. 2- In deep cavities: apply base in deep areas to protect the pulp from thermal, chemical or traumatic irritation of the restorative material or its technique. 3- Non vital teeth: according to the remaining tooth structure. f. Size of the cavity: ◦Small cavities can be restored with gold foil, amalgam, composite, or glass ionomer R. M. ◦Medium size cavities are better restored with amalgam, cast gold, composite or glass ionomer R.M. ◦Large cavities should be restored with cast gold, ceramics, amalgam or full coverage restorations. g. Location of the cavity: Anterior teeth: - Mesial cavities: restored with esthetic restoratives. - Distal cavities of cuspids: restored with amalgam or R.C. - Cervical cavities: restored with resin composite. Posterior teeth: - Occlusal cavities: restored with metallic or esthetic R.M (composite is preferred). - Cervical cavities: restored with amalgam, R.C. or RMGI. C. Accessibility to the cavity: ◦Wide mouth opening provides sufficient accessibility. ◦However, small mouth opening creates difficult in cavity preparation and restoration. ◦Anterior teeth, premolars and first molars are more accessible than second and third molars.  Factors concerning the operator ◦ He should have sufficient information about available restorative materials. ◦ He should have sufficient skill for manipulation and handling of restoratives. ◦ He should use the material within its indications. ◦ He should provide patient with sufficient post- restorative instructions. ◦ Successful dentist should satisfy his patients. Success and Failure of Restoration Depends upon: Material Contamination during restoration Technical expertise Oral hygiene Dietary habits