Dental Cements - Weeks 11 & 12 PDF

DENTAL CEMENTS MDA Chapter 45 Learning Objectives Lesson 45.1: Dental Cements 1. Pr o n o u n c e, d ef in e, a n d s p e l l t h e ke y t e r m s. 2. G i ve t h e c l a s s i f ic a t ion o f d e n t a l c e m e n t s , w h i c h i n c l u d es : Th r e e t y p e s o f l u t in g...

DENTAL CEMENTS MDA Chapter 45 Learning Objectives Lesson 45.1: Dental Cements 1. Pr o n o u n c e, d ef in e, a n d s p e l l t h e ke y t e r m s. 2. G i ve t h e c l a s s i f ic a t ion o f d e n t a l c e m e n t s , w h i c h i n c l u d es : Th r e e t y p e s o f l u t in g c e m e n t s. Pe r m a n en t a n d t e m p o ra r y c e m e n t s. 3. D i s c u s s t h e va r i a bles t h a t i n f lu en c e f in a l c e m e n t a tion. 4. L i s t t h e f i ve c e m e n t s d i s c u s s e d i n t h i s c h a p t e r a n d i d e n t ify t h e i r s i m ila ritie s a n d d i f fe re nc e s. 5. D i s c u s s t h e s t e p s i n c e m e n t r e m ova l. Dental Cements As a cavity liner for pulpal protection As a base for the sedative and insulation protection For insulation Pulp capping Pulpectomy Temporary restoration Restorations for deciduous teeth, cervical cavities, and anterior proximal in adults Temporary cementation for provisional coverage Permanent cementation for fixed restorations Root canal sealing Resin bonding for orthodontics brackets, Maryland bridges, and veneers Cementation in prosthodontics and pediatric dentistry Classification of Dental Cements Dental materials that May be classified into are routinely used three types according when working with to properties and indirect restorations intended use: Type I: Luting Type III: Liners or Type II: Restorative agents, which include bases placed within materials, such as permanent and the cavity glass ionomers temporary cements preparation Permanent Cements Used for the long-term cementation of cast restorations such as inlays, crowns, bridges, laminate veneers, and orthodontic fixed appliances Casting ready to be cemented. Once prepared in the laboratory, cast restorations are delivered to the dentist for the cementation appointment Figure 45-01. (A) Prepared tooth to receive indirect restoration. (B) Depending on the luting agent, it should either line or fill the entire A luting agent must have qualities that do not surface. (C) There is space for excess cement to expel when interfere with a proper fit seating restoration. (From Shen C, et al. Phillips’ Science of Dental Materials. 13th ed. St. Louis: Saunders; 2022.) Inlay/Onlay/Crown Full Crown Various Full Crowns ¾ Crown 3 Unit Bridge Maryland Bridge Veneers Orthodontic Brackets and Bands  Temporary Cements Temporar y cementation of an indirect restoration may be considered if: Dentist needs to remove the restoration at a later date Tooth is sensitive or is exhibiting other symptoms that might require removal of the cast restoration Temporar y cementation of provisional coverage is required while the patient Provisional Bridge waits until the laborator y technician completes the cast restoration Variables Affecting Final Cementation Powder /liquid and premixed capsules Self-curing, light-curing, or both A number of factors can influence the actual cementation of a luting cement Cementing errors can be the result of: Improper mixing technique and time Humidity Incorrect temperature of the glass slab Incorrect cement spatula Moisture Contamination Mixing Time Follow the manufacturer’s directions regarding a material’s exact mixing time working time delivery time Any delay between completion of the mix and seating of the cast restoration will result in the initial setting process, which could cause the casting not to seat properly Guidelines for Mixing Dental Cements Before mixing, follow the manufacturer ’s directions Determine the use of the cement; then measure out the powder and liquid according to the manufacturer ’s instructions Mix dental cements on a treated paper pad for easy cleanup Place the powder toward one end of the glass slab or paper pad and liquid toward the opposite end (the space between allows room for mixing) Divide the powder into increments Incorporate each powder increment into the liquid; then mix thoroughly Mixing time per increment will var y according to the type of material and its use Automix System Supplied in a car tridge in which they are automatically mixed as they are expressed onto the pad or directly onto the tooth sur face Provides an exact measurement of material, easy mix and application, and easy cleanup Humidity Premature exposure to warm temperatures or humidity can result in a loss of water from the liquid or addition of moisture to the powder Always dispense the powder first, then the liquid, to minimize the loss of water from evaporation Wait until it is time to mix the material before placing it on the pad Do not set it out at the beginning of the procedure  Powder-to-Liquid Ratio I n c o r p o ra ti ng t o o m u c h o r t o o l i t tle p o w d e r w i l l a l t e r t h e c o n s i s t e nc y o f t h e cement Fluff the powder in the bottle before d i s p e n s i n g t h e p o w d e r i n t h e m e a s u ri ng scoop A l wa y s h o l d t h e b o t t l e o r v i a l u p r i g ht t o Fig 45.2 Hold the bottle upright e n s u r e d r o p s o f c o n s i s t e nt s i z e w h e n when dispensing the liquid of a d i s p e n s i n g t h e l i q ui d cement. Temperature Specific types of material will have a chemical reaction during the setting stage Zinc phosphate cement generates heat (an exothermic reaction) It may be beneficial to cool a glass slab in the refrigerator before mixing the cement Make sure to thoroughly wipe the slab dry before dispensing the material so as not to incorporate any moisture condensation into the material Types of Cement Selection of cement for a specific procedure requires knowledge of the chemical and physical properties of each particular type of cement Glass ionomer cement Releases fluoride Composite resin cement Very strong Used to cement porcelain veneers Zinc oxide–eugenol cement (ZOE) Soothes pulp/decreases pain Polycarboxylate cement Kind to the pulp Zinc phosphate cement Oldest cement Very strong Mixing procedure is complicated Glass Ionomer Cement (Slide 1 of 2) One of the most versatile types of cement used in dentistry A hybrid of silicate and polycarboxylate cements Chemical bonding adhesive Adheres to enamel, dentin, and metallic materials Glass Ionomer Cement (Slide 2 of 2) Supplied in special formulations according to their use Ty p e I : L u t i n g c e m e n t u s e d f o r c e m e n t a t i o n o f i n d i r e c t r e s t o r a t i o n s ( m e t a l r e s t o r a t i o n s a n d d i r e c t - bonded orthodontic brackets) Ty p e I I : D e s i g n e d f o r r e s t o r i n g a r e a s o f e r o s i o n i n c l a s s V Ty p e I I I : L i n e r s a n d b a s e s Ty p e I V: P i t a n d f i s s u r e s e a l a n t s Ty p e V: C e m e n t a t i o n o f o r t h o d o n t i c b a n d s a n d b r a c k e t s Ty p e V I : C o r e b u i l d u p o f r e s t o r a t i o n Ty p e V I I : H i g h f l u o r i d e r e l e a s i n g l i g h t - c u r e d G I C Ty p e V I I I : G I C f o r a t r a u m a t i c r e s t o r a t i v e t r e a t m e n t ( A R T ) Ty p e I X : G I C f o r p e d i a t r i c a n d g e r i a t r i c r e s t o r a t i o n s ; r a d i o p a q u e p o s t e r i o r G I C Advantages of Glass Ionomer Slow release of fluoride from this powder aids in inhibiting recurrent decay Has a low solubility in the mouth Adheres to a slightly moist tooth surface Has a very thin film thickness, which is excellent for ease of seating a casting Can be formulated for use as a dentin substitute or base material Chemical Makeup of Glass Ionomer Cement Powder: Calcium Liquid: Polyacrylic fluoroaluminosilicate acid copolymer and glass with barium water glass Application of Glass Ionomer Self-curing or light-cured formula Bottles of powder and liquid, which can be mixed manually on a paper pad or a cool, dry glass slab Premeasured capsules that are triturated and expressed through a dispenser Figure 45-03. Glass ionomer permanent cement. (A) Disposable applicator. (B) Dispenser. (Courtesy 3M Company, St. Paul, MN.) Examples of Commercial Glass Ionomer Cement GC Fuji II FugiCem 2 Re l y X Pl u s A u t o mix C h e m F i l Ro c k GC Fuji IX GC Fuji IX Capsule Mixing Glass Ionomer for Permanent Cementation Procedure 45.1 Equipment and Supplies Paper mixing pad Spatula (flexible stainless steel) Glass ionomer powder and dispenser Glass ionomer liquid and dropper 2 × 2–inch gauze pads Mixing Glass Ionomer for Permanent Cementation Procedure 45.1 P r o c e d u ra l S t e p s 1. D i s p e ns e t h e m a n u f a c tu re r ' s r e c o m m e n d e d proportion of the liquid on half of the paper pad. 2. D i s p e ns e t h e m a n u f a c tu re r ' s r e c o m m e n d e d proportion of the powder on the other half of the pad; this is usually divided into two or three i n c r e m e n ts. 3. I n c o r p o ra te t h e p o w d e r i n t o t h e l i q ui d , f o l l o w i ng t h e r e c o m m e nd e d m i x i n g t i m e. T h e m a t e ri a l s h o u l d h a v e a g l o s s y a p p e a ra n ce. 4. C l e a n a n d d i s i n f e c t t h e e q u i p m e n t i m m e d i a te l y. How to Manipulate GC Fuji Luting & Lining Cement Type 1 - YouTube Resin-Modified Glass Ionomer Cement (RMGI) H y b ri d i o n o m e r S i m i la r p r o p e r ti e s a s t ra d i ti o n a l g l a s s i o n o m e r c e m e n t, w i t h t h e a d d i ti o n o f r e s i n H i g h s t r e n g th t y p e o f c e m e nt h a s a l o n g e r w o r k i n g t i m e a n d i s l e s s s e n s i ti ve t o wa t e r c o n t a m i na ti o n t h a n t ra d i ti o n a l g l a s s -i o n o m e r c e m e nt. B e n e f i ts o f u s i n g R M C I a r e : N o o r l i t tl e p o s t o p e ra ti v e s e n s i ti v ity Fo r m s a s t r o n g b o n d t o e n a m e l a n d d e n t i n C o e f f i c i e n t o f e x p a n s i o n s i m i l a r t o t o o t h s t r u c t u re Longer working time Fluoride release Easy to use Chemical makeup of RMGI L i q u id: d i s t ille d wa t e r, p o l ya c r ylic a c i d - m od if ie d m e t h a c r ylat e ( H E M A ) , d imet ha c r yla te m o n o m er, c a m p h o r oq uin on e Po w d e r : a l u m ino s ilic a te g l a s s , p i g m en ts Application of RMGI L i g h t -c u rin g a u tomix s y r i n g es , p o wd er / liqu id f o r m u la , a n d c a r t r id ge s w i t h m i xi ng t i p s E a s y t o c l e a n u p w i t h a t a c k c u r e c a p a b ility D i f fe re nt s h a de s R M G I b ra n d n a m e s i n c l u d e FugiCEM Re l y X L u t i n g Pl u s C e m e n t Resin-Based Cement L u t e o r b o n d t o i n d i re ct r e s t o ra ti o ns H i g he r w e a r r e s i s t a nc e c o m p a r e d t o t ra d i ti o na l l u t i n g c e m e n ts D i f f e re n t s h a d e s H i g h c o m p r e s s i ve , t e n s i l e s t r e n g th D e s i g ne d f o r : C e m e nt a ti o n o f c e ra m i c o r p o r c e l a i n i n l a y s , o n l a y s , v e n e e rs , c r o w n s , a n d b r i d g e s C e ra m ic v e n e e rs O r t h o d o n ti c b a n d s D i r e c t b o n d i n g o f o r t h o d o n ti c b ra c ke t s M e t a l -b a s e d c r o w n s a n d b r i d g e s Chemical Makeup of Composite Resin Cement These cements have physical properties comparable with those of composite resins, including: Thin film thickness Virtual insolubility in the mouth Methacrylate resins and inorganic fillers and organic silanes (adhesion) The tooth must be free of all plaque and debris and must be prepared by etching or by treatment with a bonding system before cementation Application of Resin-Based Cement Supplied: Powder and liquid mix Syringe-type applicator as a base and catalyst Versatile light-cured/dual-cured system Recommended portions of either application are dispensed onto a paper pad and mixed rapidly with a spatula Figure 45-04. Commercial Resin Cements. (A) A hand-mixing paste–paste Total-etch cement/self-etch resin/self-adhesive resin dual-cured system for temporary prostheses. (B) A single-component light- cured system for porcelain veneers. (C) A paste–paste dual-cartridge cement dispensing system that requires hand mixing. (D) A powder–liquid capsule system that is triturated. (E) Two paste–paste dual-cartridge systems that require static mixing; the top one requires a bonding agent, and the bottom one is self-adhesive. (F) A liquid–liquid system. (From Shen C, et al. Phillips’ Science of Dental Materials. 13th ed. St. Louis: Saunders; 2022.) Commercial Resin Cements Re l y X U n i c e m M a xc e m E l i t e C a l i bra C e ra m N e xu s 2 Pa n a v ia Mixing Resin for Permanent Cementation Procedure 45.2 Equipment and Supplies Basic setup E t c h i ng s y s t e m Cotton pellets A p p l i c a to r s Bonding system Re s i n c e m e nt ( s u p p l ie d i n p o w d e r / l i q ui d o r s y r i n g e t y p e ) M i x i ng p a d S p a t ul a 2 × 2–inch gauze pads Mixing Resin for Permanent Cementation Procedure 45.2 Procedural Steps 1. Apply etchant to enamel and dentin for 15 seconds; then rinse. Blot excess water with a moist cotton pellet, leaving the tooth moist. PURPOSE During this procedure, you do not want the tooth completely dry. 2. Apply a bond adhesive to enamel and dentin; then dry gently. Avoid excess adhesive on all prepared surfaces. 3. Light-cure each surface for 10 seconds. 4. Apply primer to etched porcelain or roughened metal surfaces. Dry for 5 seconds. 5. Dispense a 1 : 1 ratio onto a mixing pad; then mix for 10 seconds. Apply a thin layer of cement to the bonding surface of the restoration. 6. Once the crown is seated, margins may be light-cured for 40 seconds or allowed to self-cure for 10 minutes from the start of the mixing. NOTE For porcelain and precured composite crowns, margins must be light-cured for 40 seconds. Composite Resin vs. Glass Ionomer Cements COMPOSITE RESIN GLASS IONOMER C o m p osi te s s h o u l d b e u s e d fo r d e e p e r G l a s s i o n o m e r f i l l i n g s a re n o t t y p i ca l l y d e cay, c h i ps a n d wo r n te et h u s e d fo r ex t e n s i v e t o o t h d a m a g e. M o re d u ra bl e U s e d fo r m i n o r t e m p o ra r y d e nt a l w o r k and work needing to be done on the M o re e st h et i c ro o t s u r fa ce s b e l o w t h e g u m l i n e G o o d o p t i o n fo r p r i m a r y t e e t h b e ca u s e o f t h e i r f l ex i b i l i t y a n d t h e a d d e d b o n u s o f re l e a s i n g f l u o r i d e t o t e e t h Zinc Oxide–Eugenol (ZOE) Cement (Slide 1 of 3) Has a soothing effect on the pulp Often used on patients when postoperative sensitivity may be a concern Type I Lacks strength and long-term durability and is used for temporary cementation or provisional coverage Type II Has reinforcing agents added for the permanent cementation of cast restorations or appliances Zinc Oxide–Eugenol (ZOE) Cement (Slide 2 of 3) Type I (paste) Temp-Bond Type II (liquid/powder) Fynal Supplied as a two-paste system as Mixed on an oil-resistant paper pad temporary cement (Base & Mixing time of 30 to 60 seconds Accelerator) Setting time in the mouth of 3 to 5 Pastes dispensed in equal lengths on minutes a paper pad and mixed Figure 45-05. Temp-Bond NE, a type I temporary cement. Figure 45-06. ZOE type II cement for permanent cementation. Zinc Oxide–Eugenol (ZOE) Cement (Slide 3 of 3) Type III Indicated as a thermal base Used for placement of a temporary restoration Prepared and placed in cavity preparation Type IV Used as a cavity liner Chemical Makeup of ZOE Cement Liquid: Eugenol, water, acetic acid, zinc acetate, and calcium chloride Powder: Zinc oxide, magnesium oxide, and silica One of the least irritating of all dental cements The eugenol can have a strong odor (cloves) and may be offensive to some patients Application of ZOE Cement ZOE is mixed on an oil-resistant paper pad that will not absorb any of the liquid Take care when using a eugenol product because of its irritating qualities to the oral mucosa Try not to allow the liquid to come into direct contact with tissue When a slower set is required, a glass slab can be used The thickness of the mix is determined by the powder-to-liquid ratio, as recommended by the manufacturer Examples of Commercial ZOE Cement ZO E 2 2 0 0 Zo g e n o l Te m p - B o nd Fynal Mixing Zinc Oxide-Eugenol for Temporary Cementation Procedure 45.3 E q u i p m e nt a n d S u p p l i e s Tr e a t e d p a p e r p a d S p a t u l a ( f l e xible s t a i n les s s t e e l ) ZO E c a t a l ys t p a s t e ZO E a c c e l e ra t or p a s t e 2 × 2 – i n c h g a u ze p a d s Mixing Zinc Oxide-Eugenol for Temporary Cementation Procedure 45.3 Procedural Steps 1. Measure the pastes onto the mixing pad at equal lengths, approximately inch per unit of restoration. 2. Replace the caps immediately. 3. Incorporate the two pastes together. 4. Mix while wiping the material over an area of the mixing pad. 5. The material should be smooth and creamy and prepared within 20 to 30 seconds. 6. Immediately fill the temporary coverage with the cement. PURPOSE Because the material has weaker properties than are seen in the permanent cement, fill the provisional rather than line it. 7. Clean and disinfect the equipment immediately. Mixing Zinc Oxide-Eugenol for Permanent Cementation Procedure 45.4 E q u i p m e nt a n d S u p p l i e s Tr e a t e d p a p e r p a d o r g l a s s s l a b S p a t u l a ( f l e xible s t a i n les s s t e e l ) Z i n c oxi d e p o w d e r a n d d i s p e n s e r E u g e n o l l i q u id a n d d r o p p e r 2 × 2 – i n c h g a u ze p a d s Mixing Zinc Oxide-Eugenol for Permanent Cementation Procedure 45.4 P r o c e d u ra l S t e p s 1. M e a s u re t h e p o w d e r a n d p l a c e i t o n t o t h e m i x i n g p a d. Re p l a c e t h e c a p o n t h e p o w d e r i m m e d i a t e ly. 2. D i s p e ns e t h e l i q ui d n e a r t h e p o w d e r o n t h e m i x i ng p a d. Re p l a c e t h e c a p o n t h e l i q ui d c o n t a i ne r i m m e d i a te l y. 3. I n c o r p o ra te t h e p o w d e r i n t o t h e l i q ui d a l l a t o n c e ; s p a t u l a te f o r 3 0 s e c o n d s. 4. I n i ti a l ly, t h e m i x i s p u t t y -l i ke , b u t w i t h a d d i ti o na l mixing for 30 seconds, it will become more fluid for l o a d i n g i n t o a c a s t i ng. 5. C l e a n a n d d i s i n f e c t t h e e q u i p m e n t i m m e d i a te l y. Polycarboxylate Cement Wa s u s e d s o l e ly f o r f i n a l c e m e n t a tio n f or c a s t r e s t o ra tio ns , s t a i n les s s t e e l c r o w n s , a n d o r t h o d on tic b a n d s O r i g ina l a c i d p o l y me r wa s p o l ya c r ylic a c i d N o w t h e c e m e n t c o n t a i n s t w o o r m o r e m o n o m er s , s o i t i s t e c h n i c ally r e f e r r ed t o a s a p o l yalken oa te c e m e n t N o w u s e d f o r l o n g - ter m t em po ra r y c e m e n t F i r s t c e m e n t t h a t h a d t h e a b i lity t o c h e m i c a lly b o n d t o t o o t h s t r u c t u r e N o n i r rita ting b a s e u n d e r c o m p o s it e a n d a m a l ga m r e s t o ra tio ns a n d a s a n i n t e r me diat e o r t e m p o rar y r e s t o ra tio n N o p o s t o p e ra tive t o o t h s e n s i t ivity Chemical Makeup of Polycarboxylate Cement Liquid: Polyacrylic acid, itaconic acid, maleic acid, tartaric acid, and water Powder: Zinc oxide, magnesium oxide, aluminum oxide, and other reinforcing fillers Less irritating to the pulp than zinc phosphate cement is, and the pulpal reaction is similar to that of ZOE cement Application of Polycarboxylate Cement Available in a powder and liquid form Liquid may be measured using the plastic squeeze bottle or the calibrated syringe-type liquid dispenser supplied by the manufacturer The liquid has a limited shelf life because it will thicken as the water evaporates. Mixing is carried out on a nonabsorbent paper pad Figure 45-07. Powder and calibrated If it is necessary to increase the working syringe of polycarboxylate cement. time, a cool, dr y glass slab can be used Examples of Commercial Polycarboxylate Cement D u r e l on Po l y F Ty l o k- Plus Hy-Bond Mixing Polycarboxylate for Permanent Cementation Procedure 45.5 E q u i p m e nt a n d S u p p l i e s Tr e a t e d p a p e r p a d o r g l a s s s l a b S p a t u l a ( f l e xible s t a i n les s s t e e l ) Po l yc a rb oxy lat e p o w d e r a n d d i s p e n s er Po l yc a rb oxy lat e l i q u id ( i n p l a s tic s q u e e ze b o t t le o r c a l i b rate d s y rin ge ) 2 × 2 – i n c h g a u ze p a d s Mixing Polycarboxylate for Permanent Cementation Procedure 45.5 Procedural Steps 1. Gently shake the powder to fluff the ingredients. Measure the powder onto the mixing pad and immediately r e c a p t h e c o n t a i n e r. 2. D i s p e n s e t h e l i q u i d ; t h e n r e c a p t h e c o n t a i n e r. 3. Use the flat side of the spatula to incorporate all the powder quickly into the liquid at one time. The mix must be completed within 30 seconds. 4. A correct mix should be somewhat thick and should h a v e a s h i n y, g l o s s y s u r f a c e. NOTE If the material has lost its glossiness or exhibits a s t r i n g y “ w e b l i k e ” c o n s i s t e n c y, i t h a s b e g u n t h e s e t t i n g process and should not be used. 5. C l e a n a n d d i s i n f e c t t h e e q u i p m e n t i m m e d i a t e l y. Zinc Phosphate Cement Classif ied as two types Type I (f ine grain) Hybond Used for the permanent cementation of cast restorat ions such as crowns, inlays, onlays, and bridges Creates a ver y thin f ilm layer, which is necessar y for an accurate cementing of castings Type II (medium grain) Figure 45-08. Zinc Phosphate Cement. (From Lakshmi S. Preclinical Manual of Prosthodontics. 3rd ed. India: Elsevier; 2018.) Recommended for use as an insulating base for deep cavity preparations Chemical Makeup of Zinc Phosphate Cement Liquid: 50% phosphoric acid in water, buffered with aluminum phosphate and zinc salts to control the pH Powder: 90% zinc oxide and 10% magnesium oxide The phosphoric acid can be irritating to the pulp A liner, sealer, or desensitizer should be placed first to reduce sensitivity to the phosphoric acid Application of Zinc Phosphate Powder is divided into increments of var ying size, with each increment spatulated before the next increment is added CRITICAL: powder be added to the liquid in very small increments This method dissipates the heat of the chemical action and retards the setting of the cement Exothermic Examples of Commercial Zinc Phosphate Cement F l e c k ’s E xt ra o r d ina r y Hy-Bond Zinc F+ Figure 45-08. Zinc Phosphate Cement. (From Lakshmi S. Preclinical Manual of Prosthodontics. 3rd ed. India: Elsevier; 2018.) Mixing Zinc Phosphate for Permanent Cementation Procedure 45.6 Equipment and Supplies Glass slab (cool) Spatula (flexible stainless steel) Zinc phosphate powder and dispenser Zinc phosphate liquid and dropper 2 × 2–inch gauze pads Mixing Zinc Phosphate for Permanent Cementation Procedure 45.6 Procedural Steps Preparing the Mix 1. Dispense the powder toward one end of the slab and the liquid toward the opposite end. 2. Re c a p t h e c o n t a i n e r s. PURPOSE These materials can be affected by prolonged exposure to t h e h u m i d i t y. 3. Divide the powder into small increments as directed by the m a n u f a c t u r e r. 4. I n c o r p o ra t e e a c h p o w d e r i n c r e m e n t i n t o t h e l i q u i d. N OT E W h e n i n c r e m e n t s i z e s va r y, s m a l l e r i n c r e m e n t s a r e u s e d f i r s t. M i x i n g t i m e p e r i n c r e m e n t a l s o va r i e s ; t h e t i m e i s a p p r o x i m a t e l y 1 5 to 20 seconds. Mixing Zinc Phosphate for Permanent Cementation Procedure 45.6 5. S p a t u la te t h e m i x t h o r o u gh ly, u s i n g b r o a d s t r o ke s o r a f i g u re - 8 m ove m e nt ove r a l a r g e a r e a o f t h e s l a b. PU R PO S E Th is a i d s i n d i s s i p a t ing t h e h e a t g e n e ra te d d u rin g m i x i n g. 6. Te s t m a t e r ia l f or a p p r o p ria te c e m e n t atio n c o n s i s t e nc y. Th e c e m e n t s h o u l d s t r i n g u p a n d b r e a k a b o u t 1 i n c h f r o m t h e s l a b. To t a l m i x i ng t i m e i s a p p r oxim at ely 1 t o 2 m i n u t es. Mixing Zinc Phosphate for Permanent Cementation Procedure 45.6 Placing Cement in the Casting 7. In addition to preparing and mixing the material, the assistant will have the important responsibility of placing the cement in the casting. 8. Hold the casting with the inner portion facing upward. 9. Retrieve the cement onto the spatula. Scrape the edge of the spatula along the margin to cause the cement to flow from the spatula into the casting. 10. Place the tip of the spatula or a black spoon into the bulk of the cement; move the material so that it covers all internal walls with a thin lining of cement. 11. Turn the casting over in your palm and transfer it to the dentist. PURPOSE By having the outer portion of the casting facing up, the dentist can rotate it safely to attain a better grasp for seating it. 12. Transfer a cotton roll so that the patient can bite down on it to help seat the crown and displace the excess cement. 13. Clean and disinfect the equipment immediately. Cement Removal Once the dentist has completed the cementation procedure of an indirect restoration, the patient is asked to bite down for a few minutes on a cotton roll for the initial setting process Cement Removal Excess cement is removed from around the margins, interproximal spaces, and adjacent areas covered with excess cement If excess cement is not removed from in and around the gingival margin and sulcus of the tooth, the cement could irritate the area and cause inflammation and discomfort Figure 45-09. Cement removal with the use of an explorer to remove excess cement and to probe the sulcus gently for remnants, the proximal contact areas and sulcus are cleaned with dental floss (a knot will help remove excess cement), followed by irrigation with the air-water syringe. (From Rosenstiel SF, Land MF. Contemporary Fixed Prosthodontics. 5th ed. St. Louis: Mosby; 2016.) Removing Cement From Permanent or Temporary Cementation Procedure 45.7 Equipment and Supplies Basic setup (mouth mirror and explorer) Spoon excavator Dental floss 2 × 2–inch gauze Removing Cement From Permanent or Temporary Cementation Procedure 45.7 Procedural Steps 1. After the cement has completed its initial setting, remove the cotton rolls from the area. 2. U s i n g y o u r e x p l o r e r, e x a m i n e t h e m a t e r i a l t o e n s u r e t h e p r o p e r s e t. 3. With a firm fulcrum, take the edge of the explorer and carefully move the instrument in a horizontal direction, pulling the excess material away from the tooth. PURPOSE Pulling the material down away from the casting will stretch or weaken the material directly under the margins. 4. W i t h t h e t i p o f t h e i n s t r u m e n t a t t h e g i n g i va l e d g e o f t h e c r o w n , use overlapping strokes to remove the bulk of the cement. 5. Fo l l o w a l o n g t h e m a r g i n t o r e m o v e s m a l l p i e c e s t h a t a r e s t i l l adhering to the surface. Removing Cement From Permanent or Temporary Cementation Procedure 45.7 6. Ti e a k n o t i n t h e m i d d le o f t h e d e n t a l f l o s s , a n d p a s s i t t h r o u g h t h e c o n t a c t o n b o t h s i d e s t o r e m ove e xc e s s c e m e n t f r o m t h e i n t e rp roximal a r e a. PU R PO S E Th e k no t a d d s e x t ra m a s s f o r r e m ov ing t h e cement from this space. 7. A f t e r t h e e xc e s s c e m e n t h a s b e e n r e m ove d, t h o r o u g hly r i n s e a n d d r y t h e a r e a f o r e va l ua tion o f t h e p r o c e d u r e. What does the future hold regarding dental cements? A p p r oxima tely 9 0 % o f i n d ir ec t r e s t o ra tio ns t o d ay a r e a l l - c era mic 7 % a r e p o r c e l a in -fu s ed - to -m etal ( PF M ) 2% are full cast N o t o n e c e m e n t i s a p p l ic a ble f o r a l l d e n t a l p r o c e d u r es F U T U RE: b i o g e ne tic r e s e a r c h i n t o h u m a n t i s s u e m a d e f r o m d e n t i n a n d e n a m e l s t e m c e l l s M a t e r ials w i ll b e d e s i g n ed t o b e s o s i m ila r t o a c t u a l t o o t h s t r u c t u r e t h a t w h e n t h e y a r e a p p l ied t o a n i n d i r ec t r e s tora tion , t h e t o o t h a n d t h e r e s t o ra tion w i l l b e c o m e o n e ove r t i m e IMPORTANT INFORMATION TO KEEP IN MIND Pr e p a r e a n d m i x t h e c e m e n t e xa c t l y a s p e r t h e m a n u f a c tu re r ’s i n s t r u c tio n s s o t h a t t h e r e s t o ra tio n i s s e a t e d p r o p e r ly Re m i n d yo u r p a t i e n ts t h e i m p o r ta nc e o f ke e p in g t h e i r m o u t h o p e n a n d n o t g e t t i ng t h e area wet O n c e t h e r e s t o ra tio n i s c e m e n t e d, t h e p a t i e nt w i l l b e a s ke d h o w t h e i n d i r ec t r e s tora tion f e e l s t o h i s o r h e r “ b i t e ,” a s w e l l a s t h e ove ra ll f e e l ing w i t h in t h e m o u t h E xp l a in t o t h e p a t i en t t h a t a c e m e n t r e q u i r es 2 4 h o u r s t o c o m p l e te it s f i n al s e t t i n g A d v is e t h e p a t i en t t o t a ke c a r e w h e n c h e w i n g s t ic ky o r h a r d f o o d s o n t h e s i d e o f t h e r e s t o ra tio n d u r i n g t h i s p e r i o d Pr o p e r h o m e c a r e b y t h e p a t i e nt a n d r e g u la r m on itor ing a t r e c a l l v i s i ts , a p r o s t h es is c a n l a s t f o r t h e d u ra t io n o f a p a t i en t ’s l i fe time (our final one for Dental Materials this semester)