principles of cavity preparation 1 Flashcards
List the classifications of cavities :
class 1: pit and tissue
class 2: proximal of posterior teeth
class 3: proximal of anterior without involving the incised angle
class 4 : proximal of anterior + includes incised angle
class 5 : gingival 1/3 of lingual/palatal or labial/buccal of any tooth
class 6 is not included in GV blacks classifications but it is incase edge or cap tips
what are simple , compound and complex cavities ?
simple :1 surface
compound : 2 surfaces
complex : 3 surfaces
what kind of alteration is tooth preparation?
mechanical alteration of defective injured or diseases tooth in order to best receive a restoration
what are the internal walls of a prepared cavity ?
pulpal and axial walls
what is the Cavo-surface angle ?
junction between a prepared tooth surface wall and external surface of the tooth
what’s the difference between an external and an internal wall ?
an external wall is a wall in the prepared tooth that extends to the external tooth surface while an internal wall does not .
plural walls can be both vertical and perpendicular to the long axis of the tooth
examples of floors:
plural and gingival walls
what is a seat ?
part of prepared tooth cavity composed of the axial wall and the plural floor
part of prepared cavity composed of the plural floor , axial wall , and gingival floor :
step
least susceptible area to caries:
areas in relation to gingival sulcus . because of the presence of alkaline gingival fluid which neutralizes the acidity needed for the process of caries
tooth preparation includes:
all mechanical procedures preformed to remove all infected an affected tissues to give proper design to remaining hard dental enamel so that a mechanically and biologically sound restoration can stay in the prepared tooth
cavity form should be under force of mastication. true or false?
false
what are the biologic principles of cavity preparation\?
-protection of pulp from mechanical , thermal , bacterial , and chemical factors
-prevention of caries recurrence
-aseptic conditions
-protection of gingival and periodontal tissue
what is the thermal tolerance zone of dentin ?
85-132 F
temperature of coolant should be:
37C
lower temperature will create fogging and disturb vision and may even irritate pulp
removal of all undermined enamel is done to:
prevent caries recurrence
proper cavosurface angle is also inclined to be suitable for the type of restoration for the same reason
procedures done to protect gingival and periodontal tissue :
-avoid overhanded gingival margins of the restorations
-proper morticing during restoration of compound cavities
-proper wedging of matrix
what is meant by maintaining the mechanical principles of the cavity ?
following steps during cavity preparation for preservation of structural integrity of both the tooth and the restoration by decreasing tensile stresses to be within the physical tolerance of these structures
what are the objectives of having a cavity design ?
-adequate retention of the restoration
-resistence against fracture to booth the tooth and the restoration
-conservation of maximum amount of tooth structure
proper CSA for amalgam and for cast gold restorations :
-90 for amalgam
-obtuse for gold
two cavities on the same tooth should be connected when the distance between them is less than :
0.5mm
curves of outline form :
sweeping curves, in order to prevent recurrent caries , avoid stress concentration areas and for better esthetics
depth of penetration into enamel should be ____ for pit and fissure and ___ for smooth surface
0.2-0.5 pit and fissure
0.2-0.8 smooth surface
when should cusp capping be considered?
if extension of primary groove includes > or equal to half to he cusp incline
what is the minimum thickness of marginal ridge that should be present for the structural integrity to remain adequate ?
premolar : >1.6mm
molar: >2mm
faciolingual extension of class 1 cavity should be____ wide
1-1.5mm. to prevent weakened cusps
what is enameloplasty ?
-reshaping the enamel surface by making it rounded so that the area becomes self cleansing and food stagnation is no longer possible — indicated when remaining tissue is not greater than 1/3rd of enamel thickness
shape of outline for upper and lower premolar :
upper ;: dumbbell shapped
lower : confined to pits but if entire occlusal surface is involves then they resemble the upper premolar
in upper molars, if cavity involves all the occlusal surfaces then the preparation is___
elongated mesa-distally
if oblique ridge is not involved then the mesial preparation will have a ____ shape and the distal will have a ___ Shape
kidney
heart
how is the gingival margin placed in class 2 cavities ?
it should extend apically of proximal contact area of adjacent tooth (0.5mm clearance)
narrowest connection between the occlusal and proximal portion of class II compound/complex cavity :
embrasure wall (isthmus)
isthmus outline in class 2 cavities is dependent on :
location , dimensions and tightness of contact area
ingerhams lines in class 2 cavities:
straight- in case of open contact between teeth
uniform or universal - in case of touch or plus contact between teeth
reverse curve - in case of tight and broad contact between teeth(preserves triangular ridge of cusp, facilitates formation of 90 angle between proximal and the tan___ of proximal surface
adverse effects of extension for prevention :
-weakening of sound tooth structure
-irritation of pulp
-increased liability for gingival and periodontal problems in compound cavity
-increased liability to recurrent carries
