Luting Cements & Cementation Procedures PDF

# Luting Cements & Cementation Procedures By: Prof. Dr. Lamia Dawood ## Luting Cements * Cement: Is a plastic mass of fine powder & liquid that when harden * Retains the restoration * Occupies marginal voids * A diagram is shown representing a tooth and crown with the cement between the...

# Luting Cements & Cementation Procedures By: Prof. Dr. Lamia Dawood ## Luting Cements * Cement: Is a plastic mass of fine powder & liquid that when harden * Retains the restoration * Occupies marginal voids * A diagram is shown representing a tooth and crown with the cement between them * The arrow of fluid flow represents the cement ## Cementation * A procedure which allows full seating of a crown with no damage to tooth * Pulp irritation * Restoration (porcelain fracture) ## Cement Microstructure * An image depicts a ceramic powder particle in a yellow square next to an inorganic or organic liquid in a yellow square * Cement hardens as a result of the reaction from a basic powder and an acidic liquid * An image depicts a residual powder particle in a pink square next to acid-base salt in a pink square * The powder reinforces and enhances the set cement matrix ## Requirements of an Ideal Luting Cement 1. Adhesion to tooth structure and restoration. 2. Biologic compatibility with the pulp 3. High mechanical properties 4. Insolubility in the oral cavity 5. Anticariogenic property 6. Long working time 7. Low film thickness 8. Low viscosity and easy flow 9. Translucency 10. Easy removal of excess cement 11. Radiopacity ### Good Adhesion * To abutment preparation * Enamel * Dentin * Core material (amalgam / GI / Composite resin) * To restorative material * Metallic (precious / non-precious) * Non-metallic (all-ceramic) ### Mechanism of Adhesion * **Mechanical bond**: Interlocking into the surface roughness present on the tooth and the fitting surface of the restoration * **Chemical bond**: Occurs due to a chemical reaction between the cement and the surface to which it is bonded * A diagram shows a pink representation of the cement mechanically secured to the tooth * A diagram shows a pink representation of the cement chemically bonded to the tooth ## Types of Dental Cements 1. **Zinc oxide and eugenol**: * Conventional * Reinforced 2. **Zinc phosphate** 3. **Zinc polycarboxylate** 4. **Glass ionomer and its modifications** 5. **Composite Resin Cement** ## Zinc Oxide Eugenol Cement * **Type I (conventional ZnO/E)**: * Used for temporary restoration * ZnO/Eugenol free is used for acrylic resin temporary restoration * Eugenol softens the acrylic resin * Eugenol inhibits setting of resin cement * **Type II (reinforced ZnO/E):** * Used for final cementation * Reinforced by addition of * Alumina + resin to the powder * EBA (ethoxy benzoic acid) to eugenol * A diagram shows the ZnO/E setting reaction * The ZnO and eugenol (Eug) mix together into a zinc eugenolate chelate ### Manipulation: * Rapid incorporation of powder into liquid, followed by spatulation for 60 sec. ### Properties: 1. **Adhesion**: Only mechanical 2. **Biological compatibility**: Good * Has palliative/sedative effect on pulp 3. **Mechanical properties**: Low mechanical properties 4. **Solubility**: Soluble due to elution of eugenol 5. **Anti-cariogenic properties**: None. 6. **Working time**: Short working time 7. **Film thickness**: Thick 50μm 8. **Viscosity & flow**: Good flow 9. **Translucency**: Opaque 10. **Removal of excess cement**: Difficult ### Uses of Reinforced ZnO/E * Used in cases where it is difficult to control saliva (allow to set in a wet field) * Used in cases of sensitivity ## Zinc Phosphate Cement * **Composition:** * Powder: 90%ZnO +10% MgO * Liquid: Phosphoric acid 30-40% + water * A diagram shows the ZnO mixing with the liquid to form tertiary zinc phosphate ### Manipulation * An image shows the steps for mixing zinc phosphate cement on a slab * **A**: Powder is divided into 6 equal parts * **B**: Powder is incorporated into the liquid in increments * **C**: Mix over a large area (60% of the slab) for 15-20 sec * **D**: Total mixing time 90 seconds * **E**: The cement is of proper consistency when pulled to 20 mm thread length before snapping back to the slab * **F**: It is a white cement ### Properties: 1. **Adhesion**: Only mechanical. 2. **Biological compatibility**: Irritant to the pulp due to initial acidity * Use varnish before cementation to minimize irritation * Frozen slab use increases pH from 1 to 3 3. **Mechanical properties**: High, especially compressive strength * Frozen slab allows incorporation of more powder which increases mechanical properties 4. **Solubility**: Soluble * Frozen slab increases resistance to solubility 5. **Anti-cariogenic property**: None 6. **Working time**: 5 minutes * Setting time slowed by decreasing the rate of addition of powder to the liquid. 7. **Film thickness**: Thin 25μ 8. **Viscosity & flow**: Good flow. * Dilatants. I.e. viscosity increases when mixing rate increases 9. **Translucency**: Opaque 10. **Removal of excess cement**: Easy because it's brittle ### Preparation for Final Cementation * An image shows how the restoration and tooth surface are prepared for final cementation * The tooth is prepared using a dental bur and a polishing tool ### Cementation with Zinc phosphate * An image shows a dentist using a mirror and spatula to mix, apply and seat zinc phosphate cement ### Seating the Final Restoration * An image shows how bite sticks are being used for seating the final restoration ### Uses of Zinc Phosphate * Cement PFM restorations on conservatively prepared teeth * Cement cast post and core (metallic posts) ## Zinc Polycarboxylate Cement * **Composition** * Powder: ZnO + MgO * Polyacrylic acid 40% in H2O. * Water settable Zn polycarboxylate, acid is dried and incorporated into the powder, then the powder is mixed with H2O. * A diagram shows the ZnO mixing with the polyacrylic acid (PAA) to form a zinc polyacrylate gel ### Manipulation * **Image**: A dentist is using a spatula to mix the cement on a glass slab * Proper powder/liquid ratio on a cool, dry, clean glass slab. * All powder is mixed to the liquid. Spatulate for 30 seconds. ### Properties: 1. **Adhesion**: Chemical & mechanical * Adheres to enamel > dentin due to its higher calcium content. 2. **Biological compatibility**: Excellent * Post-operative hyper-sensitivity minimized * **Because:** * Rapid rise of pH * Large molecular size * Low toxicity of polyacrylic acid * Complex with protein, limits diffusion through dentinal tubules 3. **Mechanical properties**: * Lower compressive strength * Lower modulus of elasticity, compared to Zn phosphate cement. * Higher tensile strength 4. **Solubility**: Soluble. * Frozen slab increases resistance to solubility 5. **Anti-cariogenic property**: None 6. **Working time**: Very short (2.5 minutes). 7. **Film thickness**: Thin (25μm). 8. **Viscosity & flow**: Pseudo-plastic (viscosity decreases when mixing rate is high). 9. **Translucency**: Opaque. 10. **Removal of excess cement**: Difficult during setting. * Excess cement should not be removed while the cement is in a rubbery state. ### Indications: * Zinc polycarboxylate is recommended for retentive preparations when minimal pulp irritation is important (i.e. children with large pulp chambers) ## Glass Ionomer Cement * **I. Conventional glass ionomer:** * **Powder**: Calcium-fluoro-alumino silicate glass * **Liquid**: Polyacrylic or polymaleic * Water settable glass ionomer are available. * **II. Resin modified glass ionomer:** * **Powder**: Same as before (Calcium-fluoro-alumino silicate glass) * + Resin * **Liquid**: Water - HEMA mixture * The final set cement has 4.5-6 % resin ### Manipulation: * The powder is divided into 2 equal parts * The first is mixed with liquid for 10 seconds * The second is mixed with liquid for another 10 seconds * Proper consistency is tested as before ### Properties: 1. **Adhesion**: Similar to Zinc-polycarboxylate * Bonds well with glass ionomer core * Bonding is due to chemical similarity 2. **Biologic biocompatibility**: Non-irritant * May cause post-operative sensitivity * **To reduce sensitivity:** * Place varnish on the margin after removal of excess cement * Slightly hydrate tooth surface with a drop of H2O, blow it off before placing the restoration * Allow it to set for one minute before removal of excess 3. **Mechanical properties**: * Higher compressive strength * Higher tensile strength * Lower modulus of elasticity * Not recommended for all-ceramic, due to slow strength development * Resin-modified glass Ionomer has a higher strength value, similar to resin luting agents 4. **Solubility**: Soluble * Varnish is applied to the restoration margin to reduce the initial solubility * Resin-modified GI increases resistance to initial solubility 5. **Anti-cariogenic properties**: * Has anti-cariogenic properties due to fluoride release 6. **Working time**: 3.5 minutes * Water settable cement increases working time, due to the H2O release of the active molecule from the incorporated acid then the powder reacts * Resin-modified GI increases working time 7. **Film thickness**: Thin 20μm 8. **Viscosity**: * Excellent flow * Initial slow rise in viscosity, then rapidly increases 9. **Translucency**: Translucent * Resin-modified GI decreases translucency 10. **Removal of excess cement**: Difficult during setting * The cement goes through a rubbery state, excess cement should not be removed or it will be pulled out ### Uses: * **Glass Ionomer**: * Cementation of sandblasted metallic restorations (PFM/ cast post) * Bond to Cu/Cr/ and Al containing alloys * Not ideal for cementing ceramic restorations * **Resin-modified glass Ionomer**: * PFM restorations * Contraindicated for low-strength all-ceramic restorations * It can cause ceramic fracture due to volumetric expansion (10-15%) ## Resin Cement * **Similar to composite resins**: * Consists of a resin matrix of * Bis-GMA * UDMA * TEGDMA * Has silane-treated inorganic fillers * Silica * Glass * Colloidal silica * Requires an adhesive monomer * Dentin bonding agent * HEMA * 4-META * MDP * HEMA and MDP are in the dentin bonding agent and the resin cement * A diagram shows the resin matrix and the inorganic filler ### Conventional Resin Cement 1. Di-acrylate oligomer diluted with a low molecular weight methacrylate monomer 2. Silinated silica or glass. 3. Initiator: Peroxide amine ### Adhesive Resin Cement * **1. Curing Modalities:** * **Chemical cured**: * Used for metallic restorations * Two-component system * Mixed on a paper pad or auto-mixed * **Light cured**: * Used for veneers * Single-component system * Indication (< 1.5 mm) * **Dual cured**. * Used for post/inlays/onlays * Two-component system * Not used for restorations thicker than 2.5 mm * **2. Bonding Modalities:** * **i) Total etch or etch and rinse (3 steps)** * Variolink II/Calibra * Conventional composite resin cement * Etching with phosphoric acid, rinsing, primer, and then bonding agent * Complete removal of the smear layer * Used mainly on enamel for a strong bond * **Image:** This shows the etching, application of primer bonding agent and application of the cement * **ii) Self etch (2 steps)** * Panavia F * Adhesive resin cement * No etching with phosphoric acid * Bonding agent is applied directly to the tooth structure and cured * Resin cement is applied. * The weak acid of the primer leads to incomplete removal of the smear layer, which weakens the bond. * In old age patients, the dentinal tubules are narrow causing a dependence on chemical adhesion rather than micro-mechanical adhesion * **Image:** This shows cleaning the tooth with a brush and applying the cement * ***iii) Self-adhesive (1 step)*** * Rely X Unicem * Adhesive resin cement * No conditioning is needed * Acidic nature of the monomer allows tooth surface demineralization and the penetration of the cement. * **Image:** Shows dentist using a device to apply the cement * **3. According to Composition** * **i) 4-META based cement** * Methacryloxy ethyl trimellitate anhydride * Bonding to both the tooth structure (mechanical + chemical) * **Diagram:** This shows the bifunctional 4 META molecule containing both a methacrylate group and a trimellitate anhydride group, making it suitable to bond to both composites and metallic oxides/ porcelain * **ii) Panavia cement**: * Differ from conventional resin composite due to the addition of phosphate ester to the monomer * Contains hydrophilic + hydrophobic groups * Responsible for both chemical adhesion to tooth structure + alloys. * Sandblast with 50μ alumina for non-precious alloys, increases bond * Sandblast & tin plating (0.2-0.4μm) for precious alloy, increases bond * **Image:** This shows a chart representing the proper primers and pastes needed for bonding to each structure * **iii) Rely X Unicem (self adhesive):** * Dual cure cement * There's no need for treatment or conditioning to the surface. * The acidic nature of the monomer (phosphorylated methacrylate) allows for demineralization of the tooth surface. ### Properties: 1. **Adhesion**: * **Conventional**: Mechanical bond only. No chemical bond. * The bond to etched enamel is stronger than dentin * Dentin * Wet tissue * Contains less mineralized tissue * Contains smear layer * **Modern dentin bonding agent**: Modifies or removes the smear layer, infiltrates the exposed dentin, increasing the bond * **Image**: This shows how a bonding agent is applied to a tooth. * **Effect of acid etching on dentin** * **a) Remove the smear layer:** The smear layer is actually a coating over the dentin and enamel that is formed when the tooth is prepared with a bur * **b) Open and widen the dentin tubules (DT):** The DT are very important for the overall health of the tooth, allowing fluid to flow * **c) Demineralize the tooth surface**: Demineralization allows the bonding agents to attach (chemical adhesion) * **Priming**: Primer resin infiltrates the collagen of dentin, encapsulating and supporting collagen fibers, then resin bonding is applied and it infiltrates the demineralized substrate, creating resin microtags and then the resin-collagen hybrid layer * **b) Adhesive**: Mechanical and chemical bonding 2. **Biological compatibility**: * Irritant to the pulp 3. **Mechanical properties**: * Excellent 4. **Solubility**: * Insoluble (the only one). 5. **Anti-cariogenic properties**: * None, but recently Panavia releases fluoride. 6. **Working time**: * **Conventional**: Short working time * **Adhesive**: Controlled working time. * Unique anaerobic setting properties * The cement does not polymerize until it comes in contact with oxygen. * The oxy-guard is applied to the margin (polyethylene glycol). 7. **Film thickness**: * **Conventional**: Thick. * **Adhesive resin**: Thin (19μm). 8. **Viscosity & flow**: Viscosity increases rapidly. 9. **Translucency**: * Translucent. 10. **Removal of excess cement**: * **Conventional**: Difficult. * Remove excess immediately * **Adhesive**: Easy * Remove excess before applying the oxy-guard. ## Luting Agent Comparison Table | **Luting Agent Type** | **Chief Advantages** | **Chief Concerns** | **Precautions** | |---|---|---|---| | Adhesive resin | Adhesive, low solubility | Film thickness. History of use | Moisture control | | Self-etch adhesive resin | Low solubility, ease of use. Bonding to Dentin | Film thickness | Moisture control | | Glass Ionomer | Translucency | Solubility, leakage | Avoid early moisture exposure | | Reinforced ZOE | Biocompatible | Low strength | Only for very retentive restorations | | Resin Ionomer | Low solubility. Low microleakage | Water sorption | Avoid with ceramic restorations | | Zinc Phosphate | History of use | Solubility. Leakage | Use for traditional (cast restorations) | | Zinc Polycarboxylate | Biocompatible | Low strength. Solubility | Do not reduce powder to liquid ratio | ## Proper Selection of Luting Cements ### Cementation of Long Span Bridge: * **Cement requirements**: * ↑ Working time * ↑ Mechanical properties * Adhesive * **Cement of choice**: * G.I * Adhesive resin cement * Zn Phosphate * Zinc polycarboxylate should not be used, it has a decreased working time. * Reinforced ZnO/E should not be used, it has decreased working time and decreased mechanical properties ### Caries Active Patients (↑ caries index) * **Cement Requirements**: * Fluoride Release * **Cement of choice**: * G.I * Adhesive resin (Panavia) cement ### Deep Preparation: * **Cement Requirements**: * Non irritant * Palliative * **Cement of choice**: * Reinforced ZnO/E * Zinc polycarboxylate ### Cementation of All Ceramic Restoration & Laminate Veneers * **Cement Requirements**: * Translucency * ↑ Mechanical properties * Adhesive * **Cement of choice**: Adhesive resin cement * Glass Ionomer is not used. * It develops mechanical properties slowly, which leads to an elastic deformation of the underlying cement. ###Cementation to Core Materials: * **Cement Requirements**: * Adhesion to core material * **Cement of choice**: * **a) Amalgam core**: All cements can be used. * If it's Cu amalgam core (with high tin concentration) use Zinc polycarboxylate cement. * **b) Composite resin core**: Composite resin cement is used, due to the chemical similarity of composition. * **c) Glass Ionomer core**: Glass Ionomer cement is used, due to the chemical similarity of composition. * **d) Cast core**: * **Precious**: All cements do not provide good bonding. * Zinc polycarboxylate shows four times the greater bond than Zn Phosphate, which is directly proportional to the Cu content. * **Non-precious**: * Adhesive resin cement * Glass Ionomer * Zinc polycarboxylate (provides good adhesion) ### Cementation of Post Crown * **Cement requirements**: * ↑ Flow * ↑ Mechanical properties * Adhesive * **Cement of choice**: * Adhesive resin cement, especially for Fiber and Zirconia posts. * Glass Ionomer * Zn Phosphate ### Conditioning of Post Space * **Image**: Shows conditioning of post space with a drill * **10**: Etch the canal, coronal dentin and enamel areas with Total Etch, 5 seconds * **11**: Thoroughly rinse with sterile solution to remove etching gel * **12**: Dry the canal with paper points * **13**: Apply dual cure bonding agent, 10 seconds * **14**: Remove excess with paper points * **15**: Clean post surface with medical alcohol and dry * Composite posts do not require etching * **Image**: Shows a dentist cleaning the surface with a drill * **16**: Condition the surface with Monobond S for 60 seconds, 50 seconds * **17**: Dry with blown air free of oil and water * **18**: Dispense Variolink II in a 1:1 ratio * **Image**: Shows mixing and placing the cement * **19**: Mix Variolink II base and catalyst * **20**: Apply the cement to FRC Postec * **21**: Place the post and fully seat it, remove excess ### Cementation to a Questionable Preparation (short/overconvergence) * **Cement Requirements**: * Adhesion * ↑ Mechanical properties * Insoluble * **Cement of choice**: * Adhesive resin cement * Provides pulp protection over deep dentinal areas ### Cementation of Resin-Bonded Retainers: * **Cement Requirements**: * Adhesive to the treated metal surface * ↑ Mechanical properties * Insoluble * **Cement of choice**: * Adhesive resin cement