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Dental Materials 1
Dental Materials Test 1
| Question | Answer |
|---|---|
| Coe pack will remain workable for approximately how long? | 15 minutes |
| zinc oxide eugenol powder components: | zinc oxide: antiseptic rosin: filer and adds strength tannic acid: hemostasis |
| zinc oxide eugenol liquid components: | eugenol, mineral oil, rosin |
| advantages of zinc oxide eugenol: | easy to manipulate, slow setting reaction, can be mixed in large quantities and stored |
| disadvantages of zinc oxide eugenol: | bad taste, tissue irritation, sharp edges after setting, difficult to remove, use more pressure to adapt dressing |
| zinc oxide non eugenol: base components | zinc oxide, magnesium oxide, mineral oil, rosin oil |
| zinc oxide non eugenol: catalyst components | rosin, petrolatum, fatty acid |
| advantages of zinc oxide non eugenol | pliable, pleasant taste, easy to remove, ideal for fragile tissue, |
| disadvantages of zinc oxide non eugenol | slight tissue reaction, some people are allergic |
| how long should probing be delayed for dressing removal | 3-4 weeks |
| what is absorbable gut? | digested by the body tissue fluids and enzymes or hydrolysis |
| what are the disadvantages of surgical gut? | difficult to tie, poor knot and expensive |
| what is the absorption time for plain gut | 7-10 days |
| what is the absorption time for chromic gut? | 10-14 days |
| surgical gut is broken down by... | phagocytosis |
| synthetic sutures are broken down by... | hydrolysis |
| surgical silk must be removed no later than... | 10 day after surgery |
| what is surgical silk coated with? | beeswax or silicone |
| what created less tissue inflammation than silk? | synthetic nylon polyester sutures |
| what is a monofilament? | one thread or filament that is more resistant to harboring microorganisms but knots don't stay tied as well |
| what is a multifilament | several filaments are braided or twisted together, see a wicking effect but handles and ties easier with better retention |
| size of suture material | the higher the number, the finer the suture |
| what is a swaged end? | eyeless, suture material and needle are continuous and cut as one unit |
| how can you tell if the knot was tied too tight in a suture | tissue grown over the suture |
| how can you tell if the knot was tied too loose in a suture | abraded tissue |
| how should knots be tied in a suture | tie knots on the facial aspect, leave 2-3 mm suture tail to assist in locating at time of removal |
| what is a interrupted suture? | pierce once through the tissue on one side, pull to the other and pierce once on that side, loop back around to the first pierced tissue and tie |
| what is an interdental suture? | pierce twice through the tissue on one side, pull to the other tissue and pierce it twice, loop back around and tie where the first piercings were made |
| what is a sling or suspension suture? | pierce once on the tissue, loop around the back of the tooth and pierce on the other side of the tissue, loop around the tooth again and tie |
| what is a continuous suture? | series of suture that are tied similar to a sling but only tied at the ends |
| what should be done before suture removal? | clean sutures with cotton tip applicator dipped in chlorehexidine |
| how are single interrupted sutures removed? | locate knot, grasp the suture knot with cotton pliers, draw suture up about 2 mm and hold with tension, cut the sutra between the knot and tissue and gently pull |
| what should not be done with continuous suture removal? | do not attempt to remove continuous suture by cutting it once and withdrawing the entire length |
| how do you mix zinc oxide non eugenol periodontal dressings? | measure equal lengths of paste on wax mixing pad, mix together until uniform color, place vaseline on gloves before handling, when it is putty consistency, roll into a log |
| how do you mix zinc oxide eugenol periodontal dressings? | place powder and liquid on mixing pad, using a wooden tongue depressor gradually incorporate powder into liquid, mix until thick putty, divide mixture into log rolls |
| dycal is the... | cavity liner |
| vitrebond is the... | base |
| what is the hybrid layer? | the layer that is formed by the dentin bonding resin, the collagen fibrils and the etched dentins surface bond that links the dentin with the restorative material |
| what is special about the self etching bonding system? | etch and the primer are combined |
| what is micro mechanical bonding? | bonding using surface irregularities smaller than can be seen with naked eye or felt with a dental exolorer |
| what is macro mechanical bonding? | bonding using surface irregularities larger than can be seen with naked eye or felt with a dental explorer |
| what is percolation? | when coefficient of thermal expansion of a restorative material does not match that of tooth structure, uneven expansion and contraction occurs which causes gaps and microleakages |
| greater the surface area does what for the bonding? | greater the surface area--> the better the bonding |
| etching needs what kind of viscosity? | high viscosity so it will stay |
| adhesion needs what kind of viscosity? | low viscosity so it will flow into surfaces better |
| what is a smear layer? | a layer of debris of ground dentin created by dental instrument or bur |
| thinner layers of adhesive yields... | stronger bonding |
| chemically adhesive cements have the ability to | bond dentin and enamel, tooth structure or metal surfaces |
| what are the advantages of self etching bonding system? | reduces error of over or under etching which contribute to post op sensitivity, eliminates prate steps of etching rinsing and drying |
| what are the disadvantages of self etching boding system? | do not adequately etch uncut enamel |
| how long do you etch the tooth? | 20-30 seconds permanent dentition 60 seconds for primary dentition |
| what is primary consistency? | mix resulting in a thin consistency |
| what is secondary consistency? | thick putty like mix |
| what is cementing? | luting agent, hold and retain the restoration of appliance to teeth |
| dental cements as cavity varnish | protective barrier |
| dental cements as base/liner | protects the dental pulp in deep cavities from chemical, mechanical and thermal irritation or serves pulp therapeutically placed under restorations and is not directly exposed to oral fluids DOES NOT GIVE PROTECTION AGAINST THERMAL INSULATION |
| dental cements as buildup | stronger and thicker than a base liner, provides thermal insulation, supports the restorative materials when an excessive amount of tooth structure is missing |
| increase in powder to liquid ratio in dental cements does what? | increased strength |
| Zinc phosphate cements | used chilled glass slab to lengthen setting time by reducing the mixing temperature, higher temperature faster setting and lower strength |
| lower powder to liquid ratio for dental cements causes causes them to be... | luting |
| higher powder to liquid ratio for dental cements causes them to be... | base |
| zinc polycarboxylate cement composition | powder: zinc oxide liquid:polyacrylic acid copolymer |
| Zinc phosphate cement composition | powder: zinc oxide sometimes fluoride liquid: phosphoric acid and water |
| zinc polycarboxylate cement | slightly more acidic than zinc phosphate cement when first mixed, neutralized in 48 hours but causes sensitivity can chemically bond to the calcium tooth structure |
| zinc polycarboxylate cement mixing | mix powder and liquid with a plastic spatula on the paper mixing pad 30-60 seconds until creamy shorter working time |
| zinc oxide eugenol (ZOE) cement mixing procedure | mix powder and liquid with a stainless steel spatula on a paper mixing pad |
| zinc oxide eugenol (ZOE) cement | neutral, not irritating to the pulp, sedative effect on dental pulp but do not place directly on exposed vital pulp, not compatible with composites |
| glass ionomer cement composition | fine glass powder, liquid when powder and acid are mixed the polyacrylic acid attacks the glass particles to release fluoride ions |
| glass ionomer mixing procedure | mix on powder and liquid with a plastic spatula on a paper mixing pad do not use stainless steel spatula- glass powder abrades a stainless steel spatula and tarnish |
| resin modified glass ionomer cement advantages | increases strength, faster setting, less water soluble compared to conventional GIC, fluoride release |
| resin modified glass ionomer cement disadvantages | expansion with water absorption, all ceramic fracture risk |
| what are the applications for cavity liners and varnishes | barrier to seal tooth structure against the leakage of irritants present in saliva or restorative materials provide protective cap to the pulp in deep cavities do not have mechanical strength and provide no thermal insulation |
| what are calcium hydroxide cement used for? | liner, direct an indirect pulp capping |
| calcium hydroxide cements properties | bacteriostatic, high pH stimulates dentin self repair, low strength, does not interfere with the composite restorations |
| varnishes are what? | solution of natural or synthetic resins in a solvent, should not be used under a liner, used to coat the cavity prep prior to placement of amalgam |
| which dental cement is mixed on a glass slab? | zinc phosphate, 90 seconds |
| what is the order of a cavity prep | dycal, vitrebond, |
| what are thermoplastic polymers? | polyethylene materials (long linear chains) can e heated/ melted molded or shaped after polymerization reaction |
| what are thermoset polymers? | polymers with a cross link instead of a linear structure, can NOT be heated/melted, stronger and tougher |
| what are common polymers? | polyethylene, plastic, plexiglass are made by addition polymerization such as plastic bottles for milk and soda |
| what is polymerization? | chemical reaction that links monomers together to produce a polymer (macromolecule) |
| additional polymerization: | one monomer at a time is added to the polymer chain as the reaction proceeds |
| what are the three stages of additional polymerization | induction, propagation and termination |
| in dentistry what type of polymerization is seen most often in restorative material? | addition polymerization |
| what happens during initiation? | formation of a free radical activation: an initiator molecule becomes activated or changed to a free radical by heat, light or chemical reaction initiation: reaction of a free radical with a C=C of the monomer |
| what happens during propagation? | growth or lengthening of the chain, polymerization continues as long as monomers are available to react with the free radical at the end of the growing chain |
| what happens during termination? | two free radicals at the end of two growing chains react and will from a carbon carbon bond, no free radicals are left to continue growth of the chain |
| what chemical process does impression material use? | condensation polymerization |
| heat and chemical activated polymerization initiator... | benzyl peroxide (BPO) as the initiator |
| head activated system used for | heat serves as an activator, co2 and free radical molecules, powder liquid system, complete and partial denture |
| chemical activation system used for | powder liquid system, temporary crowns, impression trays, orthodontic retainers and other dental appliances |
| what are the advantages of the light activated dental materials | longer working time, short curing time, no mixing |
| what are the disadvantages of light activated dental materials | depends on light source, under curing in deep restorations, cannot use for cementation of metal crowns |
| dual cure activation is what | materials with both chemical and light activated capabilities, good for cementation for porcelain crowns, NO METAL FRAME WORKS |
| what does an inhibitor do during polymerization? | reacts with and destroys the first free radicals that are produced during initiation process but will become used up |
| what does adding filler do to dental resins? | increases strength, decrease polymerization shrinkage and decreases thermal expansion to nearer that of the tooth structure |
| what are the components of resin composites? | resin matrix, fillers, coupling agent, others |
| what is the resin matrix of resin composites made out of | bis GMA or dimethacrylates it is the weakest and least wear resistant, easily absorbs water stain and discolor |
| what is the filler in resin composites | inorganic compounds coated with a silence coupling agent to form a paste. The size of the filler determines the surface smoothness |
| what is macrofill | larger size particles results in restorations that feel rougher to the explorer and eye excessive wear and limited use, except bonding orthodontic bracket |
| what is microfill? | particle size smaller than macro filled, polish ver smooth and lustrous and surface appearance similar to enamel, flexes with the tooth |
| what has the best polish ability when it comes to particle size? | microfills is best due to smaller filler particle size |
| what has the most stiffness when it comes to particle size? | microhybrids |
| what has the best strength when it comes to particle size? | microhydrids |
| what is the coupling agent found in resin restorations? | silane, provides bond between inorganic fillers and the matrix |
| what conducts temperature when it comes to composites and metal restorations? | composites conduct temperature less than metals so they are good thermal insulators |
| radiopacity of the composite aids in... | detection and in the detection of recurrent decay |
| what is depth of cure? | thickness of composite that is cured by a light source, can vary with time of light exposure, composite product |
| when placing composites it is important to... | place in incremental thin layer and cure it before placing the next layer |
| what is air inhibition? | a thin air inhibited layer does not cure, when a second layer is added it excludes oxygen and the air inhibited layer and new material are chemically bonded together when the second layer is cured |
| what are unreacted c=c bonds | composite materials can be placed in layers and bonded together, a new composite can also bond to old composites |
| what are the steps to apply a resin composite? | isolation, placement of dycal, placement of mylar strip, apply acid etchant and wait 10-15 seconds, rinse tooth but not desiccate, apply primer and air dry, apply thin coat of bonding agent, add composite resin and cure, polish |
| what are the indications for finishing and polishing of composite resins | overhang or flash, high occlusion, staining, over contouring of anatomy, minor defects or chips |
| what has greater wear? amalgam or composite | composite |
| can the same bur be used on both alloy and composite? | NO, alloy particles can become embedded in the composite restoration |
| what are the sequence of the disc in the SofLex system? | black-->dark blue--> blue--> aqua most coarse to fine |
| what contributes to composite restoration greater wear? | large filler particles and lower filler content |
| finishing burrs should be used on what speed? | low speed to avoid overheating and pulpal damage |
| SofLex system works well on... | facial, incisal edges, difficult on lingual aspect of most anterior teeth |
| enhance points or cups are good on... | lingual and narrow surfaces |
| enhanced discs are good on | interproximal areas |
| flame shaped finishing burs are good on | smooth contours and margins, removing overhangs |
| finishing disks are good on | removing over contoured anatomy especially on facial and lingual surfaces |
| finishing strips are good for | remove and smooth gingival margins at the proximal contact |
| football shaped finishing burs are good for | occlusion, lingual surfaces |
| what should not be used on finished and polished composite restorations? | ultrasonic scalers or air polishing devices and prophy pastes because may damage the surface or margins of restoration |
| what should you do after you polish a composite restoration? | etch, rinse and dry then apply a thin layer of optigaurd and cure for 20 seconds |
| what time should the total polishing time not exceed? | 30 seconds on any stained surface |
| cement powder to liquid ratio is | 1 powder to 4 drops |
| base powder to liquid ratio is | 4 powder to 6 drops |
| what are the advantages of self cured sealants? | low cost, ample working time, one mix can be used on a number of teeth, excellent long term retention |
| what are the disadvantages of self cured sealants? | cannot control the setting time, mixing can create air bubbles, polymerization takes longer therefore higher rate of contamination, air inhibited layer forms |
| self cures sealants hardens in what time? | 1.5-2 minutes |
| light cured sealants hardens in what time? | 20-40 seconds |
| visible light cured sealants advantages | longer working time, less air inhibited layer formation, less chance of saliva contamination, no mixing, excellent long term retention |
| visible light cured sealants disadvantages | cost more, difficult manipulating light, need special light or glasses |
| what are the caries risk factors | diet, history of caries, salivary flow, fluoride exposure, oral hygiene |
| what are sealant contraindications? | occlusal decay that is completely though the enamel tooth with proximal decay, restoration already present, patient behavior does not permit use of dry field |
| how do you place sealants? | cleanse the tooth with pumice and water, condition the tooth with acid in a dabbing motion (do not rub) 15-30 seconds |
| what is the oxygen inhibited layer? | thin film of uncured resin that will appear shiny and wet and causes no harm |
| what is the main cause of sealant failure? | saliva contamination water in air line of air water syringe, inadequate amount of sealant or rinsing and drying |
| glass ionomer cement sealants are | can be used on partially erupted teeth, poor retention rates, releases fluoride for up to 24 months triange white for fully erupted teeth, triange pink for newly erupted molars |
| sealants with ACP | contains amorphous calcium phosphate, slowly releases calcium and phosphate ions that remineralizes tooth structures, neutralizes the acid and buffer's the pH |
Created by:
Chobchi
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