principles of cavity preparation 1

Question 1

List the classifications of cavities :

Answer 1

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

Question 2

what are simple , compound and complex cavities ?

Answer 2

simple :1 surface
compound : 2 surfaces
complex : 3 surfaces

Question 3

what kind of alteration is tooth preparation?

Answer 3

mechanical alteration of defective injured or diseases tooth in order to best receive a restoration

Question 4

what are the internal walls of a prepared cavity ?

Answer 4

pulpal and axial walls

Question 5

what is the Cavo-surface angle ?

Answer 5

junction between a prepared tooth surface wall and external surface of the tooth

Question 6

what’s the difference between an external and an internal wall ?

Answer 6

an external wall is a wall in the prepared tooth that extends to the external tooth surface while an internal wall does not .

Question 7

plural walls can be both vertical and perpendicular to the long axis of the tooth

Question 8

examples of floors:

Answer 8

plural and gingival walls

Question 9

what is a seat ?

Answer 9

part of prepared tooth cavity composed of the axial wall and the plural floor

Question 10

part of prepared cavity composed of the plural floor , axial wall , and gingival floor :

Answer 10

step

Question 11

least susceptible area to caries:

Answer 11

areas in relation to gingival sulcus . because of the presence of alkaline gingival fluid which neutralizes the acidity needed for the process of caries

Question 12

tooth preparation includes:

Answer 12

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

Question 13

cavity form should be under force of mastication. true or false?

Answer 13

false

Question 14

what are the biologic principles of cavity preparation\?

Answer 14

-protection of pulp from mechanical , thermal , bacterial , and chemical factors

-prevention of caries recurrence
-aseptic conditions
-protection of gingival and periodontal tissue

Question 15

what is the thermal tolerance zone of dentin ?

Answer 15

85-132 F

Question 16

temperature of coolant should be:

Answer 16

37C

lower temperature will create fogging and disturb vision and may even irritate pulp

Question 17

removal of all undermined enamel is done to:

Answer 17

prevent caries recurrence

proper cavosurface angle is also inclined to be suitable for the type of restoration for the same reason

Question 18

procedures done to protect gingival and periodontal tissue :

Answer 18

-avoid overhanded gingival margins of the restorations

-proper morticing during restoration of compound cavities

-proper wedging of matrix

Question 19

what is meant by maintaining the mechanical principles of the cavity ?

Answer 19

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

Question 20

what are the objectives of having a cavity design ?

Answer 20

-adequate retention of the restoration
-resistence against fracture to booth the tooth and the restoration
-conservation of maximum amount of tooth structure

Question 21

proper CSA for amalgam and for cast gold restorations :

Answer 21

-90 for amalgam
-obtuse for gold

Question 22

two cavities on the same tooth should be connected when the distance between them is less than :

Answer 22

0.5mm

Question 23

curves of outline form :

Answer 23

sweeping curves, in order to prevent recurrent caries , avoid stress concentration areas and for better esthetics

Question 24

depth of penetration into enamel should be ____ for pit and fissure and ___ for smooth surface

Answer 24

0.2-0.5 pit and fissure
0.2-0.8 smooth surface

Question 25

when should cusp capping be considered?

Answer 25

if extension of primary groove includes > or equal to half to he cusp incline

Question 26

what is the minimum thickness of marginal ridge that should be present for the structural integrity to remain adequate ?

Answer 26

premolar : >1.6mm
molar: >2mm

Question 27

faciolingual extension of class 1 cavity should be____ wide

Answer 27

1-1.5mm. to prevent weakened cusps

Question 28

what is enameloplasty ?

Answer 28

-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

Question 29

shape of outline for upper and lower premolar :

Answer 29

upper ;: dumbbell shapped

lower : confined to pits but if entire occlusal surface is involves then they resemble the upper premolar

Question 30

in upper molars, if cavity involves all the occlusal surfaces then the preparation is___

Answer 30

elongated mesa-distally

Question 31

if oblique ridge is not involved then the mesial preparation will have a ____ shape and the distal will have a ___ Shape

Answer 31

kidney

heart

Question 32

how is the gingival margin placed in class 2 cavities ?

Answer 32

it should extend apically of proximal contact area of adjacent tooth (0.5mm clearance)

Question 33

narrowest connection between the occlusal and proximal portion of class II compound/complex cavity :

Answer 33

embrasure wall (isthmus)

Question 34

isthmus outline in class 2 cavities is dependent on :

Answer 34

location , dimensions and tightness of contact area

Question 35

ingerhams lines in class 2 cavities:

Answer 35

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

Question 36

adverse effects of extension for prevention :

Answer 36

-weakening of sound tooth structure
-irritation of pulp
-increased liability for gingival and periodontal problems in compound cavity
-increased liability to recurrent carries