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Dental Materials 4
Ortho Debonding to prophy jet
| Question | Answer |
|---|---|
| what is debonding? | complete removal of composite material from enamel surfaces after orthodontic treatment |
| what are the objectives to debonding? | to return enamel surface to its pre treatment or natural appearance to return the enamel surfaces to its pre treatment texture |
| what are the problems with debonding? | enamel loss, gouges in enamel, scratches, tissue irritants, time consuming |
| what is the one instrument you can use for debonding? | tungsten carbide burr with a slow speed hand piece |
| what type of cement is on the bands of ortho? | zinc polycarboxylate cement on bands can use cavitron tip on the cement that is placed on the metal band that is placed on the molars |
| what type of cement is on the brackets on premolars and anterior during ortho? | resin |
| what is the debunking procedure? | bracket and band removal, identification of composite resin adhesive, removal of resin bulk, final finish and polishing, evaluation of criteria |
| how do you identify composite resin adhesive on patient's teeth? | patient report, stain on tooth (disclosing solution), drying tooth, exploring the tooth |
| how do you remove resin bulk? | use a scaler one time, slow speed hand piece and tapered tungsten carbide finishing bur, brush stroke in one direction |
| what is the procedure for final finishing and polishing? | aluminum oxide points aluminum oxide cups polish with tin oxide and rubber cup polish with brown polishing cup final polish with green polishing cup |
| how many patients have white spot lesions during ortho? | 30-50% |
| if patient have generalized significant white spot lesions... | the enamel is too soft to debond so put florid varnish or ACP paste on their teeth and let patient use that for 3 months |
| what would be a low risk for white spot lesion? | no previous WSL, good oral hygiene, low dietary sugar exposure, short treatment time, controlled etching, lingual appliances |
| what would be a high risk for white spot lesions? | existing WSL, poor oral hygiene, high dietary sugar exposure, long treatment time, excessive etching, labial appliances |
| are acrylic resins thermoplastic or thermoset in dentistry? | thermoset |
| what is a co-polymer? | two or more different types of monomers join together |
| what is a homo-polymer? | same type of monomers join to form the chain |
| what is the chemical reaction which occurs to form a polymer from any monomer? | polymerization |
| what does MMA stand for? | Methyl methacrylate |
| what does PMMA stand for? | polymethyl methacrylate |
| what happens when spatial structures are heated? | physics bonds break and the chains can slide past one another resulting in a soft material |
| what happens when spatial structures are cooled? | bonds reform and the material hardens |
| what is addition polymerization? | monomer molecules are added one to another sequentially as reactive group on one molecule initiates bonding with adjacent monomer molecule and it frees a free radical to repeat the process |
| when the side chains of adjacent polymers are joined by weak bonds... | polymers are easily manipulated |
| when the adjacent polymers are joined by highly charged side chains... | bond is stronger and the cross linked polymers are stronger and stiffer |
| when you increase the number of monomers to form the polymer (DP) what do you increase? | strength, stiffness, stability and compatibility |
| what are important composition in the powder for cold cure or chemically cured acrylic? | cross linking agent glycol dimethacrylate inhibitor hydroquinone |
| what is used to minimize porosity in acrylic resins? | temperature and pressure |
| what happens if monomers evaporate during handling process? | the acrylic becomes porus |
| what does glycol dimethacrylate do to MMA in cold cure acrylic resins? | increases toughness and decreases birttleness |
| what does hydroquinone do to MMA in cold cure acrylic resins? | destroys free radicals and creates working time |
| what is the physical change during polymerization? | sandy, stringy, doughy, rubbery, set doughy stage working time rubbery stage you can trim |
| what is different in the heat cured acrylic resins that is not present in the cold cure? | no chemical activator present in the liquid less inhibitor (hydroquinone) in the liquid |
| what is in the liquid of cold or chemically cure resins? | methyl methacrylate, hydroquinone, ethylene glycol, teritary amine |
| what is in the powder of cold or chemically cured resins? | acrylic resin powder benzoyl peroxide fibers and colorants |
| what is in the liquid of heat cured resins? | methyl methacrylate, hydroquinone, ethylene glycol |
| what is in the powder of heat cured resins? | acrylic resin powder, benzoyl peroxide, fibers and colorants |
| how do we pour acrylic resins? | liquid into powder |
| which acrylic resin is better for accuracy and dimensional change? | cold cure |
| which acrylic resin is better for completeness for cure? | heat cured, heat bath allows for it to cure |
| what are stock trays used for? | preliminary impressions to create study models, diagnostic casts NOT detail oriented |
| what are custom trays used for? | used to take final impression for full or partial dentures, inlays/onlays/crowns, bridges, porcelain veneers |
| how do light cured impression trays work? | sheet of preformed material is adapted over the cast, trimmed and then put under the light curing unit doesn't generate heat during polymerization |
| how are chemically cured impression trays done? | involved with mixing powder of pre polymerized beads with liquid monomer releases heat during curing process |
| how are chemically activated acrylics different that heat cured? | monomer component contains a chemical activator (amine no heat) |
| where do you place the stops on the custom tray? | 5 mm square on the buccal cusp of first premolar and mesiobuccal cusp of second molar on unprepared teeth |
| when did the NCAA mandate the use of mouth guards for football players? | 1973 |
| what is a mouthgaurd? | a resilient device or appliance placed inside the mouth (or outside) to reduce mouth injuries, particularly to the teeth and surrounding tissue |
| what are the functions of a mouth guard? | protect soft tissue, teeth, supporting structure and mandible from fracture and prevent tempormandibular joint injury |
| what are considerations when picking a mouth guard? | occlusion, dental anatomy, orthodontic status, sport, level of play and equipment |
| what is a stock mouth guard? | not fitted to teeth of alveolus, teeth must be clenched to keep in, hampers speech and breathing, generally not easily comfortably worn |
| what is mouth formed mouth guard? | cost effective but difficult to achieve a good fit, difficult to speak and breathe and adapt orthodontic appliances |
| what is vacuum formed custom mouth guard? | sheet of ethylene vinyl acetate pulled with vacuum over a cast of theme's teeth |
| what is heat pressure laminate custom mouth guard? | special machine to push EVA onto the cast, enhances the ability to laminate multiple laters of material |
| what is value? | represents the brightness of a color independent of its hue |
| what is chroma? | intensity or saturation of a color |
| what is hue? | the actual color like red, yellow, green or blue |
| what are rods and how many are there in the human eye? | 120 million light receptors respond to light and dark only |
| what are cones and how many are there in the human eye? | 6 million color receptors located in the fovea |
| when do we want to select a shade for a tooth? | before anesthesia, two weeks after bleaching treatment, before preparation of a tooth |
| what is the proper distance to select a shade from? | 6-8 inches |
| what is the proper lighting to select a shade in? | 5500 degrees Kelvin |
| what is the proper time to look at a shade selection? | 3-5 seconds, rods are exhausted after this so you need to let them rest and look at gray or blue |
| what are the causes of pulp vitality loss? | dental caries, periodontal disease, trauma, cavity prep too close to the pulp, rapid orthodontic movement, age and wear |
| what will you see extra orally if a patient has a pulpal problem? | swelling or tenderness, look at the patient's lymph nodes |
| what will you see intramurally if a patient has a pulpal problem? | tooth discoloration, fractured tooth (cracks), dental caries of large size that do not hurt, swelling at the apex of the tooth |
| what might you see on the radiographs if a patient has pulpal problem? | periapical radiolucency, widening periodontal ligament space, dental caries, fractured tooth |
| what is the rule of thumb when looking at radiographs to determine pulpal health? | radiographs alone will not determine pulpal health expose at least 2 films at two different angles |
| where do you place electric pulp tester on single rooted tooth? | middle 1/3 of crown |
| where do you place electric pulp tester on multi rooted tooth? | middle 1/3 of the crown over each root |
| what are the contraindications for electric pulp tester? | patient with cardiac pace makers teeth with crowns or large restorations |
| what does the electric pulp tester advantages and disadvantages? | suggests that the pulp may or may not be vital doesn't give the clinician information of vascular health technique sensitive (28% reliable) |
| what is a false positive? | pulp tester says the tooth is vital tooth is not vital |
| what is a false negative? | pulp tester says it is not vital it actually is vital |
| what can cause a false positive? | moisture on tooth, contact with gingiva or larger restoration, patient anxiety, fluid or exudate within the pulp |
| what can cause a false negative? | multi-rooted, poor contact, defective pulp detector, heavily medicated patient, excessive calcification, recently traumatized tooth, immature root formation |
| if the pain lasts less than 30 seconds when doing a pulp test what could it be? | dentinal hypersensitivity or reversible pulpitis |
| where should you tap during percussion test? | first tap on occlusal or insical surface then tap on the buccal or lingual aspects of the teeth |
| what tooth usually is cracked during cracked tooth syndrome? | mandibular 1st molar |
| what are the two classifications of non aqueous elastomers? | condensation: by product is released addition reaction: by product is not released |
| what is light body polyvinyl siloxanes? | syringe material, reproduces fine detail, exhibits less resistance to flow and takes longer to set |
| what is heavy body polyvinyl siloxanes? | provides less detail but exhibits excellent dimensional stability |
| how long should you wait to paint tray adhesive before taking the impression? | 5 minutes |
| how long should you wait before pouring up the impression? | 15 minutes because hydrogen gas is emitted during polymerization and cast may become pitted |
| what is the Moh's hardness of sodium bicarbonate? | 2.5 |
| what is the um of sodium bicarbonate? | 74-250 um |
| what is the um of aluminum trihydroxide? | 80-325 um |
| what is the mohs hardness of aluminum trihydroxide? | 2.5-3.5 |
| what is the um of amino acid glycine salt | 2 um to 20 um |
| what is the mohs hardness of amino acid glycine salt | 2.0 |
| what is the um of novamin calcium sodium phosphosilicate? | 25-120 um |
| what is the mohs hardness of novamin | 6.0 |
| what is the air pressure? | 50-60 psi |
| what is the water pressure? | 10-50 psi warmed to 95 degrees |
| anterior teeth angulation of prophy jet | 60 degree angle |
| posterior teeth angulation of prophy jet | 80 degree angle |
| occlusal surface angulation of prophy jet | 90 degree angle |
Created by:
Chobchi
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