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73 Cards in this Set
- Front
- Back
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What are the benefits of polishing dental restorations?
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- Good oral health
- Oral Function - Aesthetics |
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How is good oral health a benefit of polishing dental restorations?
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- Resist accumulation of food and bacteria
- Reduction in surface area and roughness - Minimize potential corrosion sites - Minimize wear rates and contract stresses soft tissue adaptation and acceptance |
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What is Abrasion?
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A grinding action produced by an aggregate of particles of greater hardness than the material being removed, which results in the formation of grooves on the surface of the material
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What is an abrasive?
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A material composed of particles of sufficient hardness and sharpness that are capable of cutting or scratching a softer material (substrate) when drawn across its surface
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What is Surface Roughness?
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(Ra): A measure of the irregularity of a finished/polished surface, reported in micrometers. Smoother surfaces have a lower Ra value, rougher surfaces have a higher Ra value
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What is the definition of Finishing?
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Mechanical process where gross irregularities are reduced, by which desired contours on a restoration or tooth preparation are developed, and by which overhanging restoration margins are corrected
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What is the definition of Polishing?
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Mechanical, chemical or electrolytic process by which the height of irregularities on the surface of a material can be reduced to create a smooth, glossy surface.
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What are the two types of Polishing?
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Mechanical Polishing
Chemical Polishing |
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How is Mechanical polishing done?
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Performed by using successively finer abrasives until a polished surface is achieved
(Most commonly used in clinical dental practice) |
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How is chemical polishing done?
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Achieved by direct attack of surface irregularities by chemicals, in order to obtain a smooth surface
(Not used in clinical dental practice) |
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How do abrasive particles act as cutting tools?
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- Particles have many edges that cut grooves in the material being abraded
- Causes plastic deformation in the surface of the material to a depth of 10 micrometers - Cutting action increases the surface hardness of the material |
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What is the size relationship of abrasive particles?
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Particle size is inversely proportionate to smoothness of the surface.
--> larger particle size = less smooth surface |
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How is finishing and polishing done?
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In sequence from course to fine abrasive particle size to minimize time required to produce a smooth, contoured surface
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How do you minimize injury to the tooth during finishing/polishing?
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- Heat generated by the frictional forces should be reduced
- This extends the life of the tool - Reduces damage to heat sensitive restorative materials - Minimizes patient discomfort |
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how do you minimize heat buildup during finishing/polishing?
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- By using liquid or air coolant
- If no coolant indicated then use abrasives intermittently |
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Movement of a bur in direction _____ of its rotation results in a smooth abrasive action.
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Opposite
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How is abrasive hardness a factor affecting rate of abrasion?
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Harder abrasives cut faster
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How is abrasive particle shape a factor affecting rate of abrasion?
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Sharp edges cut faster than round edges
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How is abrasive particle size a factor affecting rate of abrasion?
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"Grit" is a measure of the average size of abrasive particles
- Larger particles, which are more abrasive, have a smaller grit number |
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How is the brittleness of abrasive particles a factor affecting rate of abrasion?
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Fracture of brittle particles exposes more edges
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How is substrate brittleness a factor affecting rate of abrasion?
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Brittle metals abrade rapidly, ductile metals clog tool
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How is amount of force applied a factor affecting rate of abrasion?
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Increased in force --> increased abrasion rate --> more heat generated
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How is rotational speed of the instrument a factor affecting rate of abrasion?
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Higher speed --> Increased abrasion rate--> Less pressure required
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What are the factors affecting the rate of abrasion?
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- Abrasive hardness
- Abrasive particle shape - Abrasive particle size "Grit" - Brittleness of abrasive particles - Substrate brittleness - Amount of Force Applied - Rotational Speed of the Instrument |
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What are the different types of abrasive instruments?
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- Bonded Abrasives: Sintered, vitreous-bonded, resin-bonded, rubber bonded
- Coated Abrasives: Disks, Strips - Truing Procedure - Dressing Procedure - Abrasive Blinding |
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What are the abrasives used in dentistry?
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Arkansas stone
Chalk Chorundum Natural Diamond Synthetic Diamond Emery Garnet Pumice Quartz Sand Tripoli Zirconium Silicate Cuttle Kieselguhr Silicon carbide Aluminum Oxide Rouge Tin Oxide Abrasive Pastes |
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What are the 2 types of wear?
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- Abrasive wear:
--> two body wear --> three body wear - Erosive wear: --> mechanical erosion --> chemical erosion |
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What do dentrifices do and what types are there?
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- Clean and polish toothbrush-accessible surfaces of teeth
- Enhance esthetics - Reduce incidence of dental caries - Maintain gingival health and reduce intensity of mouth odors (halitosis) - Types: toothpastes, gels, powders |
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What is a detergent?
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Lowers surface tension of dentrifice and removes debris from tooth surface
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What is Humectant?
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Prevents dehydration, eg. sorbitol, glycerine, propylene glycol
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What is a binder in a dentrifice?
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Controls consistency, keeps abrasives in suspension, eg. sodium alginate
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What do sweetening and flavoring agents do for a dentrifice?
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Acceptable taste and flavor, eg. saccharine, mannitol, sorbitol
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What do abrasives do for a dentrifice?
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Removes exogenous stains but not tooth structure
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What are the commonly used dentrifice abrasives?
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Calcium Carbonate
Dicalcium Phosphate Dihydrate Anhydrous Dicalcium Phosphate Tricalcium Phosphate Calcium Pyrophosphate Sodium Metaphosphate Hydrated Alumina Silica |
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(True/False)
Dibasic calcium phosphate can activate the fluoride ion |
False it inactivates it
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What are the therapeutic agents in a dentrifice?
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Fluorides, antibacterials (xylitol, triclosan)
Desensitizers (Potassium Nitrate) |
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What are some factors in choosing dental dentrifices?
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- Degree of staining
- Toothbrushing habit (method, force, stiffness of the brush) - Amount of exposed Cementum and Dentin - Soft restorative materials that are susceptible to abrasion from use of dentrifice with toothbrush (eg polymeric resin materials silicate and GI cements) |
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What are the extraoral factors affecting dentifice abrasivity?
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- Abrasive type, size, and quantity in the dentifrice
- Amount of dentifrice used - Toothbrush type - Toothbrushing method, force applied when brushing, frequency and duration of brushing - Patient's coordination ability |
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What are the intraoral factors affecting dentifrice abrasivity?
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- Saliva consistency and quantity
- Exposure of dental roots - Xerostomia induced by drugs, salivary gland pathology, and radiation therapy - Presence, quantity and quality of existing dental deposits (pellicle, plaque, calculus) - Presence of restorative materials, dental prostheses and orthodontic appliances |
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What are prophylaxis pastes used for?
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The removal of exogenous stains, pellicle, materia alba and oral debrise from tooth surface
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What are the ideal characteristics of prophylaxis pastes?
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- Cleansing agent with no undue abrasion of the tooth structure
- Polishing agent - Anti-cariogenic agent (NaF, SnF) - Able to reduce enamel solubility |
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What should Prophylaxis pastes precede in an appointment?
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Fluoride
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What are the common abrasives used in prophylaxis pastes?
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- Zirconium Silicate
- Pumice - Quartz - Montmorillonite - Anatase - Kaolinite - SiO2 - NaF - Stannous Fluoride - Aluminum Hydroxide - Talc |
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What are the better prophylaxis cleaners?
What is their downside? |
Pumice and quartz clean the best but are also more abrasive
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What should you avoid when using prophylaxis pastes?
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Excessive abrasion of
- Denture based resins - Artificial tooth resins - Acrylic veneer - Restorative resins (These are all suseptible to wear) |
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How are soft deposits removed from dentures?
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Brushing followed by a rinse
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How are hard deposits removed from dentures?
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Professional re-polishing of the denture
Soaking and or brushing the denture daily using a denture cleaner and a denture brush |
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What denture cleaner decomposes in water to release peroxide and oxygen?
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Sodium Perborate
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What denture cleaner contains a known allergen that has been linked to allergic responses?
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Potassium Monopersulfate (FDA 2008)
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What are the less commonly used denture cleaners?
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Calcium Carbonate, Hydrated Silica, Citric Acid, Isopropyl alcohol
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What are the requirements for denture cleaners?
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- Non-toxic and easy to remove
- No irritants left behind - Removes organic and inorganic deposits from denture surface - Harmless to denture materials and liners - Harmless to cloths skin and eyes if spilled - Stable on storage - Preferably bactericidal and fungicidal |
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How should you store dentures?
Why? |
- Room temp. water NOT hot
- Dry dentures can undergo 5% volumetric contraction causing improper fit - Lightly brushing is ok but not with hard bristtles |
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Tooth powders and creams for dentures are very _____.
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Abrasive
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What kinds of solvents should you avoid for denture cleaning?
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Organic Solvents:
- Alkaline Peroxides, perborates and chloroform areharmful to soft liners - Alkaline hypochlorites cause bleaching and corrosion of alloys and leave odor/taste behind - Dilute acids corrode alloys |
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What is required to remove calculus and stain from dentures?
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Professional repolishing
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What are the two In-office bleaching solutions?
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Hydrogen peroxide (30-50%)
Carbamide Peroxide (34-44%) |
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What are the characteristics of the Carbamide peroxide in-office bleaching system?
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- 30 min per treatment in a custom fabricated tray.
- Can be done before starting daily home bleaching - Several Visits are necessary |
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What are the characteristics of the Hydrogen peroxide in-office bleaching system?
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- Power Bleaching
- Activated with a halogen lamp, laser or heat source - One treatment followed by home maintenance - Gel contains silica for further consistency - Refrigerator storage needed |
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What should be used for protection during an in-office bleaching appointment?
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- Rubber dam and eyewear for the patient
- Constant monitoring of the patients treatment |
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What is the bleaching solution used in at home bleaching treatments?
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- Carbamide peroxide (10-22%)
- H2O2 (1.5-6%) - Non-peroxide whitening gel - pH ranges from 4.3-6.6 |
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What is required before at home bleaching is done?
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Plaque removal
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What is the length of an at home treatment?
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2-4 hours during the day or the night in a custom fabricated tray made by the dentist
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How long does at home bleaching take to get noticeable results?
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3-6 weeks and periodic follow ups with the dentist is recommended
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What are the characteristics of over-the-counter at home bleaching systems?
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- Heat softened trays
- Lower concentrations of peroxide - No professional supervision |
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What is bleaching effectiveness related too?
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Number of hours used
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When is In-office bleaching recommended for use?
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For Fluorosis, tetracycline stains, and acquired superficial discoloration
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What do bleaching products not affect?
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Gold Alloys
Amalgam Porcelain Microfilled Composite Resins |
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What materials are roughened by bleaching products?
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Hybrid and microhybrid composite resins
Hybrid ionomer and glass ionomer cements |
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What happens when you bleach mixed dentition?
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A Mismatched appearance after the child is in permanent dentition
- Use caution when bleaching primary dentition |
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Can you bleach enamel or dentin or both?
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Enamel only
Peroxide bleaching agents easily diffuse through 0.5 mm dentin to produce cytotoxicity |
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Peroxide bleaches are cytotoxic in _____ to their concentration.
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Direct proportion
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How should you handle anesthesia with tooth whitening?
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Do not use anesthesia prior to tooth whitening because it can mask irritation of the pulp
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What are the side effects of bleaching?
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- Tooth sensitivity
- Temporomandibular joint problems caused by tray - Sore throat and Nausea (from swallowing bleach) - Soft tissue lesions caused by ill-fitting trays - Increased marginal leakage around existing restorations - Oxygen released can interfere with polymerization of resin containing dental materials such as bonding agents - Light source for power bleaching is harmful to a patients eyes, so protective eyewear is necessary |
