haneen

1
Definition Pit and fissure cavities that
involves  1- Occlusal surface of molars and
premolars.  2- Occlusal 2/3 of buccal and lingual
surface of molars.  3- Palatal pits in maxillary
anterior teeth. 
2

• 1st Outline form
• There are 2 important guidelines
• (1) carious tooth structure should be eliminated
• (2) margins should be placed on sound tooth
  structure. Any enamel that has been undermined by
  the removal of carious dentin should be removed (
  the fissure should not extended , instead it
  would be sealed after the amalgam has been
  placed).
• External 
• 1- Sweeping curves. 
• 2- In upper premolar, buccal wall (convex
  curved), lingual (Semi- straight). 
• 3- Buccal pit cavity in lower molars -
  triangular. 
• 4- Buccal pit cavity in upper molars- round. 
• 5- Lingual pit in upper anterior - oval

3

• Internal 
• 1- lingual and buccal wall should be parallel to
  the respective tooth surface or converge
  occlusally). 
• 2- Mesial and distal walls should be diverging
  from pulpal floor to prevent undermining the
  marginal ridges. 
• 3- pulpal floor should be perpendicular to long
  axis of the tooth except in lower first premolar,
  and parallel to occlusal plane in order to 
• A- to bring force perpendicular to floor. 
• B-Susceptibility to pulp exposure. 
• 4- Preparation should be widened only to obtain
  enamel margins supported by sound dentin.
• 5- No sharp angle ( although that , sound tooth
  structure should not removed so easily for that).
• 6- Dentine ledge is an option to prevent rotation

4

• 2nd  Resistance form 
• 1- Cavosurface angle should be 90 (To have
  sufficient bulk to prevent fracture of amalgam). 
• Notes If
• Angel gt90 - amalgam fracture or restoration
  fracture. 
• Angellt90o - enamel fracture or tooth fracture. 
• Both will form Ditch v-shaped space in the
  margin of restoration due to fracture of the
  undermined enamel of amalgam margin.
• 2- Pulpal floor parallel to occlusal plane. 
• 3- Dentin walls at right angel to pulpal floor. 
• 4- Line angels and point angels should be
  slightly rounded to prevent stress concentration
  of forces at sharp area to prevent fracture of
  tooth. 
• 5- mesial and distal wall are diverge occlusally
  following enamel rods.
• 6- faciolingual width is one third the distance
  between the tips of cusps , unless they are
  unable to withstand the forces it should be
  included.
• 7- depth should bulky as 1.5 mm or 0.5 mm apical
  to DEJ to resist fracture during function.
• 8- If there is direct occlusal contact between
  the opposing tooth and the weakened marginal
  ridge, the marginal ridge should be removed and
  restored with amalgam.
• 9- Extending around the cusps to conserve tooth
  structure and prevent the internal line angles
  from approaching the pulp horns too closely.
• 10- Keeping the facial and lingual margin
  extension minimal as possible between the central
  groove the cusp tips.
• 11- Minimally extending into the marginal ridges
  (only enough to include the defect) without
  removing dentinal support.
• 12- Eliminating a weak wall of enamel by joining
  outlines that come close together (i.e., less
  than 0.5 mm apart

5

• 3rd  Retention form 
• 1- If the cavity provides effective retention no
  special retentive features are required. 
• 2- Pulpal floor shouldnt be rounded to prevent
  movement of restoration and leads to tooth
  structure fracture. 
• 3- Convergence occiusally from buccal and lingual
  walls in order to 
• A- Parallel to enamel rods. 
• B- 90 degree of cavosurface angel to prevent
  undermining of enamel rods. 
• C- Parallel to corresponding surface. 
• 4- Prevent undermining of marginal ridges. 

6

• 4th planning of enamel walls (Noys principles)
• A- Enamel walls finished from any short or
  undermined enamel. 
• B- Enamel walls meet tooth surface at right
  cavosurface angel. 
• C- All sharp corners in enamel must be rounded. 
•  
•  
• Buccal, lingual, and palatal cavities 
• 1- A triangle with its base forming gingival wall
  and its side forming the mesial and distal
  walls. 
• 2- The gingival wall is placed at or slightly
  occlusal to the height of contour of the teeth. 
• 3- All walls extended just to eliminate defective
  enamel and dentin. 
• 4- Enamel walls are placed in the direction of
  enamel rods 
• perpendicular to axial wall. 
• 5- In buccal cavities - triangular in shape. 
• 6- In palatal cavities-) oval or rounded in
  shape. 
• Buccal, lingual, and palatal extension
• 1- Mesial and distal walls of buccal extension
  should be parallel to each other, parallel to
  long axis, perpendicular to gingival wall,
  perpendicular to buccal surface. 
• 2- If the caries still gingival to pulpal floor,
  a step is indicated. 

7

• Definition
• Smooth surface cavity occurring in gingival third
  of buccal and lingual surface of all teeth,
  except the palatal pits of upper anterior teeth.
• Cavity preparation
• 1- The preparation should be extended only enough
  to provide removal of caries and unsupported
  enamel.
• 2- There is no need to make sharp internal line
  angles, nor to remove sound dentin for actual
  depth greater than 1-1.25 mm. ( 0.5 mm to DEJ and
  075 mm in cementum).
• 3- The cavosurface margins should be as close to
  90 degrees as possible. 
• 4- Cavosurface bevels are contraindicated with
  amalgam because of its low edge strength. 
• 5- With this design, the walls of the Class 5
  preparation often diverge facially from mesial
  and distal sides because of the curvature of the
  tooth surface which result in no retention so,
  retentive we introduce retentive grooves.
• 6- Grooves should be placed in the dentin of both
  the occlusal and gingival walls to help retain
  the amalgam(0.25 mm).
• 7- All the external are perpendicular to the
  external tooth surface and parallel to enamel
  rods.
• 8- The axial wall is convex in both directions.
• 9- The axial wall should be deeper at the incisal
  wall