cavity prep

Question 1

dental caries

Answer 1

degredative pathological process that causes defect (cavity) in enamel or in enamel adn dentin; disease that attacks tooth

Question 2

4 objectives of cavity prep

Answer 2

1. remove caries
2. meet bio reqs of tooth
3. preserve max natural tooth
4. meet mech/phys reqs of restorative material

Question 3

father of dentistry

Answer 3

GV Black

Question 4

cavity prep classification, general

Answer 4

class 1 to class 6

1. structural defect origin
2. posterior proximal surface
3. anterior proximal surface – no incisal edge
4. anterior proximal surface – yes incisal edge
5. gingival (cervical) third of F/L surface of any tooth (if M or D, not class 2)
6. incisal or occlusal edges due to wear/chewing/grinding

Question 5

class I

Answer 5

• originate in structural defects (pits in fossae, fissures in grooves)
• not just occlusal surfaces, also in lingual pits
• MD walls of this prep diverge; BL walls converge

Question 6

class II

Answer 6

• originate on proximal surfaces of PM and molars
• smooth surface caries usually – food traps/poor flossing
• box in prep; use occlusal surface for retention
• if M or D involved on a posterior tooth – it class II (except when cervical 1/3 involved and then class V)

Question 7

class III

Answer 7

• originate on proximal surfaces of anteriors
• does NOT involved loss/removal of incisal edge (that is IV)
• usually smooth surface caries

Question 8

class IV

Answer 8

• proximal surface of anteriors and DOES involve incisal edge
• can be due to trauma
• same as 3 but with incisal edge

Question 9

class V

Answer 9

• gingival/cervical third of F or L crown surface of ANY tooth
• smooth surface caries
• can extend to M or D – in this case, proximal surface caries is NOT class II
• might have to cut a class II to get to it
• might connect to cementum

Question 10

class VI

Answer 10

• incisal edge of incisors or cusp of canine/PM/molar

- forms from wear–patient chewing/grinding

Question 11

cavosurface angle vs margin

Answer 11

• cavosurface angle = angle of tooth structure formed by jxn of prepared wall and external surface of tooth
• cavosurface margin = actual jxn of the 2 walls

Question 12

line angle vs point angle

Answer 12

line angle = 2 walls meet (ex: buccal cavosurface angle or mesiopulpal angle)

point angle = corner where 3 walls meet

Question 13

7 steps in cavity prep

Answer 13

1. outline form
2. resistance form
3. retention form
4. convenience form
5. removal of caries
6. finish prep walls
7. cleanse

Question 14

strongest enamel margin

Answer 14

1. full length enamel rods

2. buttressed by progressively shorter rods whose outer ends are cur but inner ends are on sound dentin

Question 15

outline form

Answer 15

• clean DEJ, smooth, no sharp angles
• do not remove healthy tooth unless indicated
• remove unsup.enamel
• be conservative – has less of an effect on inter/intra arch relationships and esthetics and strength of tooth
• strongest enamel margin has to do with dentin supported enamel

Question 16

resistance form

Answer 16

• prevent fracture of remaining tooth and/or restoration
• round sharp angles
• wall angulation: floors are perpindicular to long axis of tooth (gingival adn pulpal walls) and walls (including axial) are parallel to long axis
• depth is just within dentin for amalgam (need bulk for resistance)
• if too wide, decrease strength
• internal line angles: slightly round to decrease stress concentration, help with uniform depth, delineate prep walls, prevent rotation of restoration (increase retention)

Question 17

depth, width, wall angles of resistance forn

Answer 17

• depth for amalgam - just within dentin, need bulk
• width can’t be too great or decrease resistance
• walls parallel to long axis, floors perpindicular

Question 18

retention form

Answer 18

prevents dislodgement of restoration.
occlusal convergence.
retentive grooves adn points

Question 19

finish cav.prep walls

Answer 19

• remove unsup.enamel

- smooth cavosurface margins (bevel)