Luting Agents PDF

Lu#ng Agents Adhesion: The force that binds two dissimilar materials together, when they are brought into in9mate contact • Solid + Solid = Poor Adhesion • Liquid + Solid = Good Adhesion • Types of Adhesion: Mechanical, Physical, Chemical • Mechanical o Adhesion is simplest o Mechanical interlocking...

Lu#ng Agents Adhesion: The force that binds two dissimilar materials together, when they are brought into in9mate contact • Solid + Solid = Poor Adhesion • Liquid + Solid = Good Adhesion • Types of Adhesion: Mechanical, Physical, Chemical • Mechanical o Adhesion is simplest o Mechanical interlocking of components o May result from presence of surface irregulari9es o Adhesive must penetrate into surface irregulari9es • Physical o Two surfaces in close proximity o Secondary forces of aErac9on arise through dipole-dipole interac9on between polar molecules o This type of bonding is rapid, reversible, and not suitable for a permanent bond • Chemical is a strong bond o Molecules dissociate aGer adsorp9on onto the surface, and cons9tuent components then bond themselves separately by covalent or ionic forces o Sharing of electrons between the two atoms in the chemical bond dis9nguishes it from physical adhesion Adhesion Promotors • Coupling Agents: An intermediary substance that is able to bond to both materials involved (ex. Silane) • Primers: Modifies surface characteris9cs of one of the two materials involved so a bond can be created (ex. Rely-X Ceramic Primer) Defini9ons • Lu@ng Agent: A material that fills the gap between the tooth and the indirect restora9on to holds them together. • Working @me: The period of 9me, measured from the start of mixing, during which it is possible to manipulate a dental material without an adverse effect on its proper9es. • Mixing @me: Part of the working 9me specified or required in order to obtain a sa9sfactory mix of the components of the dental material. • SeDng @me: The period of 9me, measured from the start of mixing un@l the cement has set, according to criteria and condi9ons prescribed for each par9cular material. Desired Proper9es • Good working & seSng proper9es (long working 9me, short seDng 9me) • Adheres well to tooth structure & the indirect restora9on • Provides a good seal • Biocompa9ble (non-toxic to the pulp, non-irrita9ng) • Adequate strength proper9es (good tensile & shear strength) • Compressible (can produce a thin layer) • Low film thickness (25 microns or less) • Low viscosity • Low solubility (will not dissolve) Important Proper@es & Components to Consider When Selec@ng Lu@ng Agent • Radiopacity: able to differen@ate between a cement line or recurrent caries • Consistency: affects ability to seat restora9on • Handling: easiness to load into restora9on and clean up • Film Thickness: higher thickness could hinder complete sea9ng • Strength and Wear Resistance • Working 9me and SeSng 9mes • Shades: Opacity/Translucency • Thickness of restora9on Addi9onal desired Proper9es • Low thermal conduc9vity • Easy clean up • An9bacterial • Radiopaque • Releases fluoride Types of Cements (Provisional/Temporary and Permanent Cements) Provisional: Used for a period between the prepara9on and sea9ng of the defini9ve restora9on Goal: to seal, preven9ng marginal leakage → preven9ng pulpal irrita@on • Zinc oxide-based: self cure (ex. Tempbond, Tempbond NE, TempoCem, Tempocem Non-Eugenol) o Tempbond/Tempbond NE • Paste/Paste: Base and Catalyst • Place equal amount on mixing pad • Mix and place in temp • SeSng 9me 3-4 mins • Tempbond available in unidose o Tempbond VS. Tempbond NE • NE = NO EUGENOL • Residual eugenol may inhibit the polymeriza9on of resin materials (such as resin cements) • Eugenol provides a “seda@ve” effect on the pulp • Obtundent: an agent that diminishes pain percep9on and/or touch • May be used to provisionally cement defini9ve restora9on-BE CAREFUL • Lightly Vaseline exterior surface of provisional just prior to cementa9on, allows for easier clean up • Have pa9ent bite on wet gauze, water will accelerate set, facilitate clean up • White color NOT indicated for anterior translucent provisionals • Resin based: dual cure (Ex. Tempbond Clear, Provilink) o Tempbond Clear – Provilink (resin based-dual cure) • Color is the main reason for use (comes in many shades) • Easy to remove from provisional and tooth • Will not retain on poor reten9on crown (if too much taper is present on your prep) Polycarboxylate o Zinc oxide (plus magnesium oxide, stannic oxide, and other salts) + polyacrylic acid → Zinc polyacrylate o Introduced in 1968 o MT: 30 secs WT: 2.5 mins (1.75-2.5 mins) ST: 10 mins (6-9 mins) o Film thickness: <25 microns • Advantage • Adheres to tooth structure • Adhere to stainless steel • LiSle pulpal irrita9on – large molecular size of polyacrylic acid can’t penetrate den9n tubules Disadvantage • Greater solubility • Essen9al to follow manufacturers instruc9ons for powder/liquid ra9o • Need to work fast (30 secs), sudden rapid increase in viscosity – use before it loses it’s sheen • More difficult to remove than zinc phosphate • Not recommended as a permanent lu9ng agent, but makes good provisional cement Permanent Cements: Categorized according to matrix forming species (bonding mechanism) o Phosphate ** o Phenolate ** ** = acid-base reac9on (acid + metal oxide base → salt + water) o Polyacrylate ** o Resin • Comes in powder/liquid and paste/paste form • Mixing o By hand o Mechanically: Capsule in an Amalgamator Zinc Phosphate • [90% zinc oxide, 10% magnesium oxide] + 67% phosphoric acid → Amorphous zinc phosphate • One of the oldest cements being used-1878 • MT = 2 mins (longest) WT = 3 ½ mins (1 ½-5 mins) ST = 5-14 mins (longest) • Film thickness: < 25 microns Advantage • Long track record • Acceptable film thickness (25 microns) • Acceptable sea9ng strength • Acceptable solubility • Easy to clean off excess Disadvantage • Does not bond to tooth • Soluble in oral fluids • Opaque color • Very low pH Glass Ionomner • Aluminosilicate, other glass powders, some with fluoride + aqueous solu9ons of polymers and copolymers of acrylic, itaconic, tartaric, maleic acid → glass par9cles surrounded by silca gel in a matrix of cross linked polyacrylic acid • Introduced in Europe – 1975 • Introduced in the U.S. - 1977 • Mixing o MT: 10–30 secs WT : 2–3.5 mins ST: 6-9 mins o Film thickness: <25 microns o Mixing – Incorporate powder into liquid in bulk as quickly as possible o Essen9al tooth is isolated and undisturbed for the en9re seSng 9me, sensi9ve early moisture contamina9on (5+ minutes), protect with resin coat Advantages: Wide range of desirable proper9es including: • strength • fluoride release • low solubility (will not dissolve) • translucency • radiopacity • low film thickness • good sea9ng • substan9ally decrease micro leakage • Adheres to enamel and den9n • Contains inhibitory effect on growth and adherence of cariogenic oral bacteria Disadvantages • Ini9al slow seSng • Moisture sensi9vity • Post-cementa9on sensi@vity • Contamina9on of unset cement with water • Hydraulic pressure forcing acid into den9nal tubules • Desicca9on of den9n prior to cementa9on (dry, but not too dry) • Incorrect powder/liquid ra9o or mixing technique Resin-Modified Glass Ionomer (powder/liquid and paste/paste) • Acid/Base reac9on of tradi9onal glass ionomer with self cure amine-peroxide polymeriza9on reac9on cross linkage between the two matrices (some do have methacrylate polymers for dual cure capabili9es) • Combines the desirable proper9es of glass ionomer cements with the strength and low solubility of resins • Introduced in the 1990’s • WT=2 ½ - 3 ½ mins ST=3 - 7mins • Film Thickness: 3-25 microns (good for crowns that do not have much thickness) Advantages Disadvantages • Adheres to tooth structure • Affected by expansion due to water exposure • Less suscep9ble to early moisture exposure • NOT recommended for ceramic restora9ons and • Releases fluoride (less than conven9on GI) posts – possible fracture • Low irrita@on to pulp • Resin Cements VERY TECHNIQUE SENSITIVE — Rely X-VC (Light-Cure) — Nexus (Dual-Cure) — Panavia 21 (Self-Cure) o o o o Must be used with a bonding system Ability to reduce microleakage and increase reten@on Must be aware of working 9mes Must be aware of different film thickness • Light cure - 5-22 microns • Dual cure - 13-48 microns • Self cure - 19-50 microns Types of Resin cements and uses • Light Cure Only: • Metal free restora9ons < 1.5mm in thickness • Metal free orthodon9c retainers • Metal free periodontal splints • Dual cure • Metal-free inlays • Metal-free onlays • Metal-free crowns • Metal-free bridges • Any applica*on that a curing light might reach, but you want some added assurance that the cement will cure • Self cure • Metal-based inlays • Metal-based onlays • Ceramometal crowns and bridges • Full metal crowns and bridges • Endodon9c posts • Metal-based resin-bonded bridges • Bonded amalgams Cementa9on steps • Following try-in, wash the restora9on with water • Clean with alcohol to remove contaminates sandblast internal por9on of restora9on to insure max reten9on. • Isolate quadrant containing tooth being restored • Use coEon rolls, “Dry Tips”, suc9on devices, rubber dam when possible • Retrac9on cord may also be required to control gingival fluids. o • • • • Clean Prepara9on o Remove residual temporary cement o Pumice à Rinse à Dry o Do not desiccate (over dry) Mix cement and place in restora9on o Mechanical mix and place o Use small instrument or brush Seat crown o Have pa9ent bite on a resilient plas@c s9ck or orange wood s@ck Final Steps • Remove excess cement with explorer and/or scaler • May run knoSed floss through interproximal to remove cement • Some cements may need protec@ve coa@ng along margins • Verify occlusion and proximal contacts