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Operative/Restorativ
Vet Dentistry
Question | Answer |
---|---|
What types of procedures are encompassed in operative & restorative dentistry? | operations to restore dental tissues as necessitated by resorption, caries, traumatic injury, impaired fxn, or esthetic preference |
What is an ABUTMENT? | A tooth, crown, or portion of an implant used to support, stabilize, or anchor a fixed or removable dental prosthesis such as a bridge |
What is a BRIDGE? | a dental prosthesis that replaces the crown of one or more missing teeth |
What is a CORE? | Substructure for a crown (may be part of a post and core system) |
What is a CAP/CROWN? | a restorative that covers part or all of the clinical crown |
What is FLASHING? | A restorative that extends beyond the preparation outline |
What is an INLAY? | A restoration made to fit into a tooth |
What is an ONLAY? | a restoration made to fit over a tooth to cover the incisal edge or occlusal cusp either partially or completely |
What is an OVERHANG? | an excess of restoration projecting beyond the parameters of a preparation margin resulting in a projection or shoulder |
What is a PONTIC? | The portion of a bridge that replaces a missing tooth |
What system is used to classify carious lesions? | G.V. Black classification |
What tooth surface(s) is involved in a simple caries? compound? complex? | simple: single tooth surface compound: 2 tooth surfaces when prepared complex: 3+ tooth surfaces when prepared |
What tooth surface is involved with a GV black class I caries? | beginning in structural defects (i.e. pit, fissure, developmental groove. commonly on occlussal surface) on any tooth (I, PM, M) |
What tooth surface is involved with a GV Black class II caries? | proximal (can also involve occlussal surface) on PM or M |
What tooth surface is involved with a GV Black class III caries? | proximal on I or C (incisal angle NOT included) |
What tooth surface is involved with a GV Black class IV caries? | proximal on I or C w/inclusion of incisal angle |
What tooth surface is involved with a GV Black class V caries? | gingival 1/3 of the facial or lingual surface of any tooth (I, C, PM, M) |
What tooth surface is involved with a GV Black class VI caries? | defect of incisal edge or cusp |
What is a STAGE 1 tooth injury? | simple fracture of enamel |
What is a STAGE 2 tooth injury? | fracture extends through enamel into the dentin |
What is a STAGE 3 tooth injury? | fracture extends into the pulp chamber, vital pulp |
What is a STAGE 4 tooth injury? | fracture extends into the pulp chamber, pulp non-vital |
What is a STAGE 5 tooth injury? | tooth is displaced |
What is a STAGE 6 tooth injury? | tooth is avulsed |
What is a STAGE 7 tooth injury? | root fracture, no coronal involvement, tooth stable |
What is a STAGE 8 tooth injury? | root fx combined with stage 1-2 coronal fx, tooth stable |
What is a STAGE 9 tooth injury? | root fx combined with stage 3 coronal fx, tooth stable |
What is a STAGE 10 tooth injury? | root fx combined with stage 1-4, unstable tooth |
What is a STAGE 1 TR lesion? | into enamel only |
What is a STAGE 2 TR lesion? | into dentin |
What is a STAGE 3 TR lesion? | into the pulp |
What is a STAGE 4 TR lesion? | extensive structural damage |
What is a STAGE 5 TR lesion? | crown is lost, only roots remain |
What is Basrani's staging system used for? | Alternate classification of tooth injury |
What is a Basrani stage A? A1? A2a? A2b? | crown fracture: A1: enamel only A2a: enamel, dentin A2b: enamel, dentin, pulp |
What is Basrani stage B? | root fracture |
What is Basrani Stage C | crown and root fracture |
What is the sequence of the successful dentinal defense mechanism? | 1) pain (sensible dentin) 2) pulpitis (reversible) 3) blockage of tubule by dentinal fluid or odontoblast 4) mineralization of material at exposed dentinal tubule surface and apertures 5) formation of sclerotic or tertiary dentin at the site |
What is SENSIBLE DENTIN? | capable of perceiving/transmitting pain, can provoke pulpitis |
What is INSENSIBLE DENTIN? | generally suggests a non-vital tooth |
How far into the dentinal tubules do odontoblastic processes typically extend? | 0.2-1.5 mm |
How far into dentinal tubules do nerve fibers typically extend? | 0.1-0.4 mm |
What type of nerve fibers in the dentinal tubules create the sensation of sharp pain? | A-delta |
What type of nerve fibers in the dentinal tubules create the sensation of dull pain? | C-delta |
What does the remainder of the dentinal tubule contain in addition to the odontoblastic process and nerve fibers? | fluid = hydrodynamic organ |
What different types of stimulus cause pain in sensible dentin? how? | by affecting the hemodynamics (expansion/contraction of dentinal fluid stimulates mechanoreceptor nerve fibers) temperature also stimulates fibers, and contributes to fluid contraction/expansion surface dehydration, friction, air, sugar, |
What is the cell layer closed to the dentinal tubules? | primary cell layer AKA odontoblastic cell layer |
what layer is adjacent to the odontoblastic cell layer | cell free zone |
Where is the cell rich zone of the pulp? What kind of cells are present? | adjacent, deep to the cell free zone undifferentiated mesenchymal cells |
What characteristics of a mature tooth/pulp make it less resilient to insult? | Decreased pulp chamber size-->less blood vessels, fewer undifferentiated mesenchymal cells remain in the cell rich zone |
What ideally happens when dentinal tubules are opened on the surface? | material accumulates at the surface aperture and mineralizes (similar to mineralization of plaque to form calculus) |
What is SCLEROTIC DENTIN? | more highly mineralized as a result of the tubule's obliteration as it is filled with additional mineralization (requires dead tract to form) |
What is a DEAD TRACT? | an empty dentinal tubule b/c the odontoblastic process is gone |
How is tertiary/repairative dentin formed? | by differentiated mesenchymal cells that migrate from the cell rich zone to fill dead tracts at the access |
How is tertiary dentin different from primary and secondary dentin? | less permeable, may be atubular |
What is the function of tertiary dentin? | Seals the pulp cavity to protect it from invasion by toxins/bacteria |
What are negative effects of the formation of tertiary dentin? | results in insensible dentin, lack of stimulation of pulp inflammation so pulp doesn't know when to mount immune response to insult AND can result in abnormal pulp cavity that is difficult to instrument during endo tx |
What are the 6 rules of Restoration? | 1. conservation 2. estehtics 3. contours & contacts 4. extension for prevention 5. cavity preparation 6. identification and resolution of cause |
In addition to retaining strength, why should tooth structure be conserved | the more surface area that is removed, the more odontoblastic processes are disturbed, the more the pulp will be inflamed |
Why should the contact areas, marginal form, and buccal/lingual contours be properly designed regarding restorations? | To reduce food impaction during mastication |
What is the definition of a LINE ANGLE? | Where 2 walls meet |
What is a POINT ANGLE? | Where 3 walls meet |
what is a CAVOSURFACE angle? | line angle where the wall of a cavity preparation meets the wall of unprepared tooth surface |
What is another term for the CAVOSURFACE angle? | preparation margin |
What is the CAVITY OUTLINE? What is another term for it? | the combined peripheral extent of all the cavosurfaces. AKA preparation outline |
What is the RESTORATIVE MARGIN? | the restorative surface that abuts the cavosurface angle or prep margin |
What factors are affected by the design of the cavosurface angle? | restoration retention resistance to marginal leakage physiologic contour reactions gingival health resistance to attrition, abrasion, and fraction of the restoration/tooth |
What factors are considered in choosing the design of the cavosurface angle? | 1. type of restoration 2. restorative materials to be used 3. degree of anticipated stress demand on the restoration 4. length/direction of enamel prisms |
What are 5 basic types of marginal finish for crowns, onlays, and inlays on any tooth surface except gingival? | 1. slight bevel 2. short bevel 3. long bevel 4. full bevel (chisel) 5. no bevel (butt) |
In addition to the marginal finishes for tooth surfaces, what are 5 more types used on gingival cavosurfaces? | 1. shoulder 2. chamfer 3. deep chamfer 4. feather (knife edge 5. occult (feathered restorative margin, but no cavosurface prep) |
What types of cavosurface preparations are used with bonded restorations/inlays/onlays made from composite, metal, porcelain, porcelain fused to metal, and glass ionomer? | beveled butt joints shoulder joints chamfers |
When are knife edge/feather and occult finish lines used? | metal onlays |
What is the result of using an occult finish line? | oversized restoration that can only be used where occlusal space allows and esthetics are not of concern |
What are the 7 steps of cavity preparation outlined by GV Black? | Outline form Resistance form Retention form Convenience form Pathology removal form Wall form Preparation cleansing form |
What is macromechanical retention? | involves undercuts in dentin. Used with nonbonded amalgams and self or auto-curing composites |
What is micromechanical retention? | use of bonding agents that microscopically interlock in enamel porosities, dentinal tubules, or other microscopic anatomy |
When do chemical crystal formations occur? | with glass ionomers, they form a crystal between the ionomer and the minerals within the enamel/dentin |
What component of amalgam is cause for concern? | mercury |
What characteristic of amalgam is improved with increased levels of mercury? | plasticity, ease with which it can be compacted to acceptable cavity and marginal adaptation before it sets |
What characteristic of amalgam is degraded with increased levels of mercury? | tensile strength |
What factors affect the deterioration of the surface and margin by corrosion and tarnishing? | alloy combination proper trituration effective compaction freedom from moisture during placement smoothness of final finish oral hygiene level |
How can marginal corrosion benefit a restoration? | in limited amounts, it improves the marginal seal |
What affects the dimensional stability of amalgam | The presence of moisture during mixing or placement results in expansion |
What is CREEP? | SLOW FLOW OR CHANGE IN SHAPE OF AMALGAMS DUE TO CHRONIC PREsSURES |
What size defects are amalgam restorations good for? | small to medium, must be supported by sound tooth structure |
What properties of amalgam are of concern? | low edge tensile strength creep/distortion under physical stress inability to materially bond to dental structure high thermal conductivity |
What is the most common cause for failure of amalgam restoration | improper cavity preparation |
What GV Black classes of lesions are suitable to use amalgam restoration? | Class 1, 2, 3, & 5 |
What are adverse effects of under trituration? | increased expansion high susceptibility to corrosion and tarnish decrease in strength increased failure rate of restoration |
What are adverse results of over trituration? | contraction of amalgam poor flow difficulty in complete filling |
What thickness of cavity liners be when used for indirect pulp cap under a restoration? | 0.5 mm (as thin as possible to minimize the void left under the restoration after the body absorbs the CaOH) |
What thickness of cavity liners be when used for direct pulp cap under a restoration? | 0.5 - 2 mm (minimum depth necessary) |
Why are cavity varnishes or bonding agents used under amalgam restorations? | to reduce marginal leakage and sensitivity |
What is WORKING TIME of a dental material? | The time from completion of mixing until the setting reaction begins |
How do you know the working time of a glass ionomer has ended? | when the surface sheen is gone from the mix |
What should be done as soon as the ionomer working time ends to prevent dehydration? | apply a moisture barrier (oil, varnish, or resin) |
Why are light cure ionomers better? | they have a resin incorporated within them that is set during curing which eliminates the need for separate application of a barrier |
When is glass ionomer sensitive to the effects of moisture? | during working, setting, and maturation |
How is adhesion of glass ionomer affected if the tooth surface is dessicated? | greatly reduced |
What happens if there is moisture contamination during glass ionomer placement? | restorative easily dissolves and can be washed out of the prepared site |
What happens if there is moisture contamination during Glass ionomer setting? | cloudy spots appear as a result of microcracks |
What beneficial component leaches from glass ionomer during setting? | flouride |
How does the bond form between glass ionomer and tooth? | the material is attracted to the calcium of the tooth and the silicate of the glass |
Why does glass ionomer bond more strongly to enamel than dentin? | higher calcium content |
What are the 4 classes of glass ionomers? | I luting cements II esthetic restorative III bases/liners IV admixtures |
What are type I luting cement ionomers used for? | cementation or orthodontic bands and crowns |
What are type II glass ionomers used for? | restorations when fluoride release is desired but esthetics and strength are not as critical (i.e. TR lesions in cats) |
What are type III glass ionomers good for? | use in deep cavity preps (incl. feline TR) b/c they have enhanced pulp compatibility (still need appropriate CaOH liners when indicated) |
How are type IV glass ionomers different? | contain a substantial metallic component (gold, silver, or amalgam alloy) |
What are type IV glass ionomers used for? | buildups and cores but due to weak nature, contraindicated in stress bearing areas |
What is COMPOSITE? | resin which is a reaction product of bisphenol A and a glycidyl methacrylate (bisGMA) |
What activator is most commonly used in chemical cure composites? | benzoyl peroxide |
What activator is most commonly used in UV light cure composites? | benzoin methyl ether |
What activator is most commonly used in visible light cure composites? | camphoroquinone |
What are the 3 basic components or PHASES of composite resins? | matrix phase (resins) dispersed phase (filler particles) coupling phase (coating of filler particles) |
Why shouldn't the occlussal cavosurface of class I and II restorations be beveled? | it enlarges the surface area of the composite in the occlusion (less strong, wears faster than enamel) & thinned areas of composite along the margins are more prone to fracture from occlusal stress-->marginal leakage |
What dental tissue does composite bond most strongly to? | enamel |
Should the margin of a class V restoration be beveled near the cementoenamel junction? | not if it will remove the enamel portion of the margin to which the composite will bond |
What type of bur can be used for beveling the cavosurface to enhance bond strength? | coarse diamond (but be careful to avoid trapping air bubbles in the groves created in the tooth surface (impairs bonding) |
What is acid etching used for? | to selectively dissolve dental or restorative surfaces-->microporosities to enhance micromechanical interlock |
What are the 2 most common acid etchants? | nitric and phosphoric acids |
How is nitric acid effective? | must be continuously rubbed |
What concentration of phosphoric acid is used to etch enamel? dentin? | 35-38% for enamel 10-38% for dentin |
What type of polishing paste should be used after cleaning the tooth, before etching? | completely water soluble, flouride free |
How long should enamel be etched? dentin? | 30-40 seconds for enamel 10-15 seconds for dentin |
What is the result of prolonged etching? | creates an insoluble calcium precipitate on the surface which reduces bond strength |
How long should the tooth be rinsed after etching? | 10-20 seconds |
What happens if the tooth is rinsed for too long after etching? | damages the etched surface which reduces bond srength |
Where is enamel bonding the weakest? why? | along cavosurface margins in the cervical enamel b/c of the anatomic makeup of enamel in that site |
What is the purpose of using enamel bonding agents? | improved retention and decreased marginal leakage |
Why do materials bond more strongly to enamel than dentin? | Higher inorganic composition of enamel (96% compared to 70%) and interference of smear layer that forms on dentin, blocking tubules |
What is the typical bond strength of resins to enamel? | 210-250 kg/squared cm |
what depth should composite increments be placed to ensure adequate light curing? | 2 mm |
within what time frame can additional layers of composite be added to achieve strength similar to that if they were placed all at once | 5 minutes |
What is dental CRAZING? | the formation of microscopic cracks induced by stress |
When are self threading and friction retained pins best utilized? | in vital teeth w/adequate elasticity |
When are drilled holes and cemented posts or pins best utilized? | in non-vital teeth or those of advanced maturity b/c decreased elasticity makes them prone to crazing and fracture |
What different mechanisms of retention are used for pins? | threaded, cemented, or friction-retained |
What is the most versatile pin type regarding which teeth it can be used in w/causing crazing? | cemented |
Which type of pin provides greater retention strength? | self-threading |
What change in size increases retention strength of pins? | increased diameter |
At what depth of insertion do self-threaded pins achieve optimal retention? | 2 mm |
At what clinically practical depth of insertion do cemented pins achieve reasonable retention? | 3 mm |
What DO pins do when used with a restoration? What DONT they do? | increase retention DONT increase strength |
At what depth into the restoration does a pin provide optimal retention, beyond which it just further weakens it? | 2 mm |
What are the rules for pin placement? | do not place closer than 0.5 mm to DEJ avoid injury to vital pulp tissues avoid injury to periodontal tissues when 2+ pins are used, place as far apart as possible (minimum 1-2 mm apart) |
What benefits do pins provide? | enhance resistance form and retention form |
What is the LINE OF DRAW? | the direction that a restoration must follow to be correctly placed on a tooth without binding |
How far into the root canal should an endodontic dowel extend for proper retentive and resistance form? | a distance equal to the height of the eventual restoration (usually 2X as much post in the canal as is exposed prior to restoration) |
What are 2 things that can cause discoloration of enamel in dogs? | tetracycline ingestion during enamel development and fluorosis |