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226 Cards in this Set
- Front
- Back
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what aspects of biomechanics are factors that contribute to the fracture of endodontically treated teeth
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1. osseous support (C:R)
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which restorative concepts to minimize the adverse effects of biomechanics are all about minimizing shear forces
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1. intact arch
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occlusal stresses transmitted to roots exacerbate what
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vertical root fractures
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should anterior or posterior teeth principles (shear and compressive stresses) be applied to premolars?
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mand PMs - anterior teeth, max PMs - posterior teeth
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primary indication for prefab posts
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RETENTION of core
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prefab post retention increases with what characteristics?
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1. length (6-9mm)
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prefab post fracture potential increases w/ what characteristics?
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1. diameter
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T/F: length increases fracture potential
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F: but length DOES increase potential
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ideal post guidelines in regards to length
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1. ideal 2/3 root length
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post guidelines in regard to width
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1/3 root diameter
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how much intact chamber height is considered sufficient to retain amal core?
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4mm
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ways to increase retention of restoration in badly broken down posterior teeth
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1. counter-sinking amal to orifices
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how far do prefab posts need to be away from CDJ?
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0.5mm
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pins w/ post generally add what type of resistance
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anti-rotational resistance (esp imp for single rooted teeth)
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T/F: pins increase strength w/in the core
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F: they reduce strength in core: more pins = more stress w/in core
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why would it be bad to place a pin too peripherally
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may interfere w/ requirement for prep
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prefab post advantages over cast posts
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1. asepsis
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how would multiple posts be considered into biomechanics?
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if bridge abutment, lateral forces are distributed into roots via post = bad
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minimal necessary restoration for ant tooth w/ intact marginal ridges
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no crown, no post, fill to cervical level, double seal, and composite core
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minimal necessary restoration for broken down ant tooth needing crown
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always need post
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minimal necessary restoration for any PM you intend to crown
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always need post to add shear strength, and composite core
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minimal necessary restoration for any molar tooth
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cuspal coverage
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surface tx of tri-R post enhances what
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adhesion to cement
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advantages of using tri-R post
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1. maximum parallelism
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T/F: you always need to retx an old silver cone if post space is needed
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T
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if you have <2mm of chamber height, would you need a post?
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always
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strategic placement for posts
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1. longest straightest canal
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how many posts do you place if you are missing 1, 2, 3, and 4 cusps?
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1: 0 or 1 posts
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which restoration requires the greatest amount of peripheral tooth reduction
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full porcelain
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which control zones generally correspond to which posts
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#45: yellow tri-R
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what are the requirements for using a 3 vs 2 step tri-R post?
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>/= 21.5mm = three step
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what type of post retention is the last resort for FEW cases of needing added retention
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treaded retention
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an endodontically tx perm mand 1st molar has incipient lesions on M and D surfaces. during previous tx, minimal amt of tooth structure was removed. the appropriate tx for this tooth is:
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MOD cast gold onlay
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crown of endo tx max lat incisor is fractured near gingival margin. the coronal end of silver cone used in filling canal is visible at that level. the findings reveal that existing root canal filling meets all criteria to be judged successful. how do you obtain necessary post space?
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remove silver cone and re-treat canal using GP technique, then create needed post space
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C. to enhance the lateral force resistance
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A. to strengthen the root
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which type of xray is best for assessing the crown of the tooth
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bitewing
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how does calcificatioin affect orifices?
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calcification moves orifices centrally over the furcation
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T/F: there is a correlation between radiographic canal size to actual canal size
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FALSE
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what 2 teeth in the mouth have canals that are larger in the F-L dimension on radiograph
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max central and palatal root of max molar
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local anesthesia failures are the biggest problem in which teeth
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mand molars w/ irreversible pulpitis
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local anesthesia failure rate in normal patients
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10%, due to technical difficulty or anatomy
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local anesthesia failure rate in pts w/ irreversible pulpitis w/ single IAN and demonstrating lip numbness
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up to 81%
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explanations for local anesthetic failures
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1. anatomic (accessory innerv)
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classical view of local anesthetic action
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anesthetic effect is all or none
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thermal stimulation is used to establish diagnosis...when else is it used?
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to confirm profound pulpal anesthesia
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adjunctive anesthetic techniques in maxilla/mandible/universal
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maxilla - periosteal infiltration
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last resort to complete pulpectomy
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intra-pulpal injection
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indications for intra-pulpal injection
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1. pt experiences pain w/ chamber exposure
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T/F: intra-pulpal injection provides no periapical (osseous) relief
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T
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key to successful anesthesia w/ intra-pulpal injection
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back pressure
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radius of canal curvatures differentiates between what
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sweeping curvatures and dilacerated root curvatures
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which canal curvature can be altered by orifice movement
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the most coronal
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orifice movement is critical for which teeth
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posterior teeth
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straight line access requires the reduction of what
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primary canal curvature
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what is essential for correct rotary
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entry angle
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do what file motions to assist the file in and out of the canal
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use continuous passive watch-winding motion
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to reduce cervical binding of file, create room by
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anti-curvature filing (forces file against orifice wall)
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final step in orifice movement
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#6GG
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requirements for #6 GG
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1. must be able to place pilot tip easily into orifice
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function of #6 and #5 GG
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access refinement and orifice movement
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pre-requisite to #4 GG - NiTi rotaries
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upright files/ long axis refinement (verification of straight line access)
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what happens when a novice over instruments curved canals apically w/ files during balanced force
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transportation and apical mishaps
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T/F: both transportation and breakage are curvature related
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T
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opposing forces of balanced force concept
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1. dentinal force
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cutting resistance force
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dentinal force
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only force present in straight canals
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dentinal force
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derived from hardness of dentin
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dentinal force
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file tendency to straighten
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restoring force
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restoring force is derived from what
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instrument size and mass, radius and angle of curvature, tip to curvature distance
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in balanced forces, what keeps the file centered in the canal
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3 point contact
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when does effectiveness of balanced forces stop?
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when file does not 'feed' into canal
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file motion for canal enlargement
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balanced force
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what may be the most significant factor adversely affecting your clinic productivity
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inability to take quality working length xrays
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what is required to use EAL
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apical patency
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T/F: rubber dam is never removed
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T
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when taking xray, do you remove RD frame or position tube head first?
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position tube head 1st
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place the xray cone perpendicular to what
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files protruding from tooth
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2 major drawbacks w/ endo-ray technique
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1. may need to clamp more posterior tooth
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do buccal or lingual objects move with the head?
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lingual objects move with head
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opalescent dentin with 'obliterated' pulp spaces/chambers is found in what
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dentinogenisis imperfecta
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blunted roots, PA lesion w/o etiology, brown or blue tinge teeth that affect primary more than perm teeth is found in
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dentin dysplasia
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diff b/w type I and II dentin dysplasia
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type I-prim and perm teeth affected w/ opalescent dentin
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red or brownish discoloration from deposition of porphyrins into enamel and dentin during development is found in
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porphyria
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hypocalcification, defective and porous enamel, porosity readily discolors and readily recurs
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enamel hypoplasia
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isolated hypoplasia (brown spots)
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turner tooth
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tx for enamel hypoplasia
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micro-abrasion
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what degree of tetracycline staining does banding appear
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3rd degree
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what does tetracycline bind to
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calcium (of hydroxyapatite mainly of dentin)
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do anterior or post teeth discolor first in tetracycline staining
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anterior (by exposure)
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internal (nonvital) bleaching is reserved for what cases
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1. single tooth discoloration after RCT
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external (vital) bleaching reserved for
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1. multiple teeth or arch discoloration
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home bleaching uses what type of bleach
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10-20% carbamide peroxide
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T/F: home bleaching can bleach out dentin related stains
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T
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office bleaching uses what type of bleach
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light activated 35% hydrogen peroxide
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vital arch bleaching can be beneficial for what color of aged dentition
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uniform yellow/gray discoloration of aged dentition
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internal bleaching prognosis for traumatized tooth
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fair/poor
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what tooth related causes are easily bleached
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1. pulp necrosis
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pink blush teeth which soon turns red then gray requires what tx
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RCT due to disrupted blood vasculature
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first rule for tooth discoloration
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correct the cause
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what are some endodontically related causes of tooth discoloration
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1. obturating materials (poor coronal management)
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T/F: metallic staining is easy to successfully bleach
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F: difficult to bleach
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recurrrent decay too can lead to what color discoloration
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gray discoloration
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mech of action of bleaching
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bleaching agents are oxiders, which act primarily on organic structure (proteins) of dental hard tissue
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why is hydrogen peroxide used
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bc it is unstable and oxidizes rapidly
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bleaching matl that is caustic and burns tissue on contact, is unstable and requires refrigeration
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hydrogen peroxide
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what bleaching material slowly liberates equivalent of ~3.5% H2O2
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10% carbamide peroxide
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bleaching material that is stable until exposed to moisture and decomposes to H2O2, O2 and sodium metaborate
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sodium perborate
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how long does external bleaching last?
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4+ yrs w/ touchups
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indications for nonvital internal bleaching
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1. single tooth discoloration or teeth that have or need RCT
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contra-indications for NV internal bleaching
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1. superficial enamel stains
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worst stains for NV internal bleaching
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long duration, dark, metallic discolorations
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successful NV internal bleaching is dependent upon
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duration, degree and cause of stains along w/ pt's age
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thermocatalytic
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heat w/ hydrogen peroxide
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walking bleach
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sodium perborate sealed in
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power bleaching refers to what
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heat or light activation
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why is sodium perborate referred to as walking bleach
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b/c material is sealed in the tooth
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most common complication to internal bleaching
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apical periodontits
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what happens when the s-shaped dentinal tubules are not accounted for when bleaching
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leaves a gray cervical band
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the worst complication to internal bleaching
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cervical resorption
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cervical 'bleaching' resorption is treated w/ what to reduce acidity
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Ca(OH)2
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advantages of walking bleach internal bleaching technique
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1. less chair time, but slower
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superoxol should be reserved for what type of teeth
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mature teeth
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T/F: cavit as a temp is indicated in walking bleach used as internal bleaching technique
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F: cavit is CONTRAINDICATED
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adv of using hydrogen peroxide as vital bleaching material over carbamide peroxide
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higher activity, 3.3x stronger
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adv of using carbamide peroxide over H2O2 for vital bleaching
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longer activity, >90 min
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what has been accepted as being safe to all oral tissues
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only 10% carbamide peroxide
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when is prognosis made
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at time of completion of tx
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diagnosis of apical periodontitis lowers healing rate by how much
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10-25%
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what is the only preoperative factor to consistently decrease tx results
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presence of PA lesion
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what is the most important intra-operative factor
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rubber dam isolation
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there is a 95% success rate if GP is filled how far from the radiographic apex
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0-2mm
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if fill is shorter than 2mm then the success rate drops to what
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68%
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inflammatory insult to periapical tissues during cleaning and shaping, that results in exacerbation of pain 2-5 days afterward
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endodontic flare-up
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flare-up symptoms mimic what
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acute (painful) abscess
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which pts are more prone to endodontic flare-ups
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pts w/ seasonal allergies
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T/F: inter-appt pain has no affect on prognosis
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T
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OUCOD recall intervals
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6 mos from completion of tx and 6 mos b/w successive recalls
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what factor of RCT is the most preventable, most common and most detrimental
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coronal seal and restoration
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excellent prognosis projected success rate
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90-95%
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fair prognosis projected succcess rate
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70-80%
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T/F: all RCT procedures cause periapical inflammation
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T
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when is best MINIMAL time to evaluate long-term radiographic healing, for evidence of 'meaningful change'
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1 year recall
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what % of teeth that eventually heal demonstrate signs of healing? what % are healed?
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90% demonstrate signs of healing, 50% are healed
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what period of time should lapse after tx of teeth WITH PA lesion at time of tx to eliminate uncertainty
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2 years
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functional asymptomatic teeth with no or minimal radiographic pariradicular pathosis
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healed
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non-funcitonal symptomatic teeth with or w/o radiographic periradicular pathosis
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non-healed (diaseased)
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% success of endodontically tx teeth initially treated
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90-95%
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% success from vital, non-vital or pulpless w/o PA lesion teeth
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95%
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% success from tx of non-vital teeth w/ PA lesion
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80-85%
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% success from retreatments w/ PA lesion
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74-80%
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teeth with (diminished) periradicular pathosis which are asymptomatic and functional
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healing
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teeth w/o radiographic periradicular pathosis which are symptomatic but whose intended function is not altered
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healing
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T/F: being asymptomatic is quantification of disease resolution
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F
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a treated tooth or root that is serving its intended purpose in the dentition
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functional
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T/F: only 18-24% of RCT teth w/ PA lesions are symptomatic
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T
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presence of clinical symptoms means the tooth is not what?
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functional
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a tooth that is healing and further observation is desirable would show what characteristics
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acceptable lesion changes (reduced size &/or w/ increased density), functional, asymptomatic
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a tooth that is functional and must re-eval for outcome would show what characteristics
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no change in lesion, questionable, asymptomatic
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a non-healed tooth that is unacceptable and tx is advised would show what characteristics
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radiographically &/or clinically worsening
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endodontic therapy is completed on a tooth w/ a periapical RL. a marked reduction in size of RL can be expected in approx how long?
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1 year
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PA lesion may take as long as ____ to completely heal
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2 years
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A new pt had RCT perormed 7mo ago in another country. No historical radiographs are available. The root canal filling appears to be satisfactory, tooth is asymptomatic, and no associated sinus tract. However, a small periapical RL is evident. What tx is indicated?
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re-eval in 6mo
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flexure of dentin is transmitted to pulp via
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hydrodynamics
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when considering strength for anterior and posterior teeth, you want to have shear strength and compressive strength against what forces
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shear against lateral forces and compressive against vertical forces
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how much weakening of the tooth occurs from endo access
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only ~10%
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which forces increase with a deep overbite
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lateral/shear forces increase
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when preparing a single rooted tooth for a crown, how much cervical tooth loss occurs including cleaning and shaping
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50% (10% from C&S and 40% from minimal crown prep)
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for anterior teeth, what are 1. positives and 2. negative effects of placing a post
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1. post provides retention for core and resistance to shear fracture
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root protection requires adequate what?
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ferrule
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ideally, what length of sound cervical tooth structure
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2mm
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the ferrule effect protects the root from what
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lateral occlusal forces acting on the post
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what are the only ways to change ferrule placement
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1. crown lengthening
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you need 2mm of ferrule at least how far above the crest?
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4mm
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wedging effects are worsened by what?
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1. deep cusp-fossa relationships
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definition of working length is a distance from what to what
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from a CORONAL REFERENCE POINT to a point at which CANAL PREP AND OBTURATION should terminate
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WL varies w/ what?
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apical management philosophy
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3 criteria for an ideal reference point
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1. vertical position
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where would reference point be for anterior tooth
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at incisal edge
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diff b/w file placement in molars before and after orifice modification
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before: crossed
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orifice modification for posterior reference points facilitates what
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reproducibility
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usual reference pts for max molars
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MB cusp tip used for MB and DB
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part of the canal w/ the narrowest diameter is called
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apical constriction or minor diameter
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width of apical constriction/minor diameter
|
.25-.35mm
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opening to the exterior of the root where the nerves and vessels enter/exit root canal system is the
|
apical foramen = major apical diameter = major apical foramen = foramen
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major apical foramen is offset from true apex from what length
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.5-3mm
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the space b/w the apical constriction and apical foramen is what shape
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funnel-shape
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mean distance b/w major and minor diameters is
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.5-.67mm
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what delineates the theoretical distinction b/w the PULP and the PDL
|
CDJ
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primary advantages of EALs
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1. improve accuracy of file placement for initial WL before first xray is taken
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1st generation EAL
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1. resistance type
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2nd generation EALs
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1. impedence type
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where do 3rd generation EALs become consistent
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at apical constriction/foramen
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T/F: 3rd gen EALs are frequency dependent
|
T
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1st multi-frequency EAL
|
endex by osada
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endex measures the difference between what
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2 impedence values at 2 diff frequencies - 1 and 5 kHz
|
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calibration for endex?
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needs to be reset or calibrated for each canal
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accuracy and battery for endex?
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85-95% accurate
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how is WL measured w/ the RootZX
|
from simultaneous measurement of the impedence of 2 diff frequencies (.4kHz and 8kHz) that are used to calculate the quotient of the impedences
|
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calibration of RootZX?
|
calibrates itself upon start up - BEFORE probe is attached
|
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accuracy and battery of RootZX
|
75-100% accurate
|
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diff b/w RootZX II and RootZX
|
II added handpiece, rechargeable battery
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calibration of PAL?
|
self-calibrating
|
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how does PAL work?
|
filters irrelevant signals, selects best possible combinations of frequency
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primary components of impedence
|
resistance and capacitance
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how do 4th generation EALs eliminate erroneous readings?
|
break impedence down into primary components and measures them independently
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indications for using EALs
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all endo tx
|
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examples when EALs are indespensible
|
extra canals, perfs, objects or anatomy superimpose over apex
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what is the ONLY EAL that you turn on to allow calibration before attaching probe
|
Endo ZX II
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for Endo ZX II to work, it is essential that it has good contact to what
|
moist mucous membrane
|
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when using PAL, do you attach probe first or turn on machine first?
|
turn on machine
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when using PAL, what should you do before taking WL xray
|
remove lip clip
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when can an EAL not be used?
|
1. files cannot touch metal restoration
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most EALs are more accurate when files are in what position?
|
overextended, then re-positioned to flush
|
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most EALs are more accurate when canals are how moist?
|
damp, not wet
|
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how should the file fit the canal to improve accuracy of EAL
|
snugly
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what could cause erratic readings
|
fluid or using too small a file or touching metal
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what is a CRITICAL starting point for using an EAL
|
trial/estimated canal length
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T/F: use of EALs is contraindicated in pts w/ pacemakers
|
T
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preferred file position for WL xray
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at PDL or slightly short of PDL
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what should you do if cone fit is >1mm short or long
|
verify EAL WL before taking a new xray w/ files
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what could it mean if there is an unstable rapid/wild wondering (wide swings in dial w/ slight file movement)
|
cervical leakage
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what could it mean if there is an immediate apex sign when inserted
|
severe bleeding or exudate, moisture in chamber or contacting metal, too much electrolyte
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what could it mean if there's a sharp drop of signal at apical foramen
|
too small of file size or canal too dry
|
