Cavity preparation

1. CAVITY
PREPARATION IN
PRIMARY TEETH
Dr. Masar Mohammed

2.  INTRODUCTION
 BASIC PRINCIPLES IN THE
PREPARATION OF CAVITIES IN
PRIMARY TEETH
 CLASS I CAVITIES
 CLASS II CAVITIES
 CLASS III CAVITIES
 CLASS IV CAVITIES
 CLASS V CAVITIES
 RECENT CONCEPTS IN RESTORATIVE
DENTISTRY

3. Operative dentistry:
Is the art and science of the diagnosis,
treatment and prognosis of defects of teeth
that do not require full coverage restorations
for correction.
The aim of pediatric operative dentistry is to
maintain the tooth in the dental arch in a
healthy state, so as to prevent its loss and
the subsequent problems that will result.

4. Main reasons to control caries in primary
Dentition
 Prevent pain and discomfort.
 Prevent local infections.
 Prevent general infections
 Prevent negative attitudes and promote
keeping good oral health
 Maintenance good mastication, aesthetic
and overall well-being
 Prevent caries in permanent teeth
 Prevent malocclusion.

5. ANATOMIC CONSIDERATIONS OF
PRIMARY TEETH
1. Shorter crown.
2. Thinner enamel and dentin.
3. Larger pulp and higher
pulp horns.
4. Enamel rods in cervical
area directed occlusally.
5. Greater cervical constriction.
6. Broad, flat proximal contacts.
7. Narrow occlusal table.
8. Lighter in color.

6.  Prevention is the cornerstone of good
management of dental caries in children
 History taking is fundamental to the
execution of restorative care in the primary
and mixed dentition.
 Communication skills are essential in
obtaining a child’s co-operation in
completing treatment.

7. In the restoration of primary teeth, we
should consider the following
factors:
 The child: age, physical condition, and
cooperation among others.
 Caries degree.
 Degree of radicular reabsorption of the
tooth.
 Condition of the bone support.
 Dental material

8. BASIC PRINCIPLES IN THE
PREPARATION OF CAVITIES IN
PRIMARY TEETH.
The steps in the preparation of a cavity in a
primary tooth are not difficult but do
require precise operator control

9. Many authorities advocate the use of
small, rounded-end carbide burs in the
high-speed handpiece for establishing the
cavity outline and performing the gross
preparation.
they are designed to cut efficiently and yet
allow conservative cavity preparations
with rounded line angles and point angles.

10.  The Black’s principles with some
modification are basic principles in
the preparation of the cavities in the
primary teeth. There are three
operative steps with the use of the
high-speed handpiece:

11.  Opening and conformation of the cavity
with the use of the high-speed handpiece.
 Eliminating the caries of the buccal, lingual,
mesial and distal walls with the use of the
high-speed handpiece. Eliminate the caries
of the pulpal wall with the use of the lower-
speed handpiece.
 The third step will include dentine
sterilization and the cement base.

12. CLASS I CAVITIES
 Incipient carious lesion in child under 2
years old should be eliminated. Small cavity
preparation may be made with a No.329 or
No. 330 pear-shaped bur. We should
open the decayed area and extend the
cavosurface margin only to the extent of the
carious lesion. The preparation can be
completed in a few seconds.

13.  The outline form should include all pits,
fissures and grooves into which a sharp
explorer can penetrate.

14.  The pulpal floor should be flat or slightly
concave throughout to allow for greater
depth of the filling material, for better
distribution of stress in the restoration and
to avoid endangering the high pulpal
horns.
 The depth of pulpal floor should be
established just beneath the
dentinoenamel junction (0.5 mm) to avoid
pulp exposure.

15.  All the internal line angles should be
rounded.
 The side walls should slightly converge
towards occlusal so that the preparation
will follow the outer form of the crown.
 Beside the regular class I cavity
preparations done in primary molars,
occlusal spot preparations have been
recommended.

16. In such preparations only the carious pits or
groove is prepared and the tooth is
restored in the usual manner. These
preparations are applicable in any of the
primary molars with exception of the lower
second primary molars in which extension
for prevention including all deep pits and
fissures is recommended above all, if the
child has high caries index

17.  cavity should be covered with calcium
hydroxide . A base of polycarboxlate, glass
ionomer or rapid-setting zinc-oxide-eugenol
cement may then be placed over the
calcium hydroxide material to provide
adequate thermal pulp protection.

18.  Do not cross the oblique ridge in the upper
second primary or first permanent molars
and the transverse ridge of the lower first
primary molar unless they are undermined
with caries. These heavy ridges add
support to the tooth.

19. CLASS II CAVITIES.
 These preparations include an occlusal, an
isthmus and proximal portion. The outline
form of the occlusal step
should be dovetail-shaped
including all carious pits,
fissures, and developmental
grooves.

20.  The side walls of the occlusal step should
converge from the pulpal wall to the
occlusal surface.
 The pulpal floor should be established just
beneath the dentinoenamel junction.

21.  Angles between the side walls and the
pulpal floor should be gently rounded.
 The width of the isthmus should be
approximately one-third of the intercuspal
dimension of the tooth.

22.  The axio-pulpal line angle should be
beveled to reduce the concentration of
stresses and provide grater bulk of material
in the isthmus area, which is liable to
fracture

23.  The greater constriction of primary teeth
increases the danger of damaging the
interproximal soft tissues during cavity
preparation.
 Extreme care must be taken when
breaking through the marginal ridge to
prevent damage to the adjacent proximal
surface, especially when the bur is
revolving at high speed.

24.  The proximal box line angles and walls
should converge towards the occlusal.
When viewed from the occlusal aspect
the resulting axial wall should follow the
outline of the original proximal surface.

25.  An axiobuccal and axiolingual retentive
groove may be included in the preparation.

26.  The bur is used in a pendulum-swinging
fashion to undermine the marginal ridge
and at the same time to establish the
gingival depth.
 The gingival seat should be of sufficient
depth to break contact with the adjacent
tooth.
 A liner or intermediate base should be
placed before the insertion of the silver
amalgam.

27.  The amalgam restoration in the Class II
cavity needs the use of a matrix retainer.
The matrix should be rigid enough to allow
adequate packing pressure, ensuring a
well-condensed restoration free from an
excess of residual mercury.

28.  If the primary molars have an extensive
carious lesions, especially first primary
molars, should be used a stainless steel
crowns, above all, in the first primary molar
of a 3 years old child

29. Indications for use Stainless Steel
Crown
 Restoration of primary molars requiring
large multisurface restoration.
 Restorations in disabled persons or
others in whom oral hygienic is extremely
poor and failure of other materials is
likely.

30.  Restorations of teeth in children with
rampant caries.

31.  Restoration of teeth after pulp therapy

32.  Restoration of teeth with developmental
defects

33.  Restoration of fructured primary molar

34.  As abutment for space maintainer

35.  In children with bruxism

36.  Restoration of hypoplastic young
permanent molars

37. Steps of preparation and placement of
Stainless Steel Crown.
 Evaluate the preoperative occlusion.
 Administer appropriate anesthesia.
 Establish access.
 Reduction of the occlusal surface.

39.  Proximal reduction.

40.  Round all line angles

41.  Selection of the crown

42.  Contour the crown.
 Place the crown and check the occlusion.

43.  Smooth and polish the crown margin.

44.  Rinse and dry the crown.
 Dry the tooth and seat the crown
completely.

45.  Remove cement excess and rinse oral
cavity.
 Check occlusion

46. CLASS III CAVITIES
 Carious lesions on the proximal surfaces of
anterior primary teeth sometimes occur in
children whose teeth are in contact and in
those children who have evidence of arch
inadequacy or crowding.
 If caries is not extensive, disking by sand
paper disc is performed to remove the
decay, and then fluoride is applied topically

47.  If the carious lesion not involves the incisal
angle, a small conventional Class III cavity
may be prepared and the tooth may be
restored with glass ionomer or composite
resin.

48. The same basic principles for permanent
anterior teeth should be considered in a
primary teeth, modified, of course, by the
size of the pulp and the relative thinness
of the enamel. If it is necessary we modify
the Class III cavities with the use of
dovetail on the lingual or occasionally on
the labial surface of the tooth.

49. Because of the narrow labiolingual width of
the primary incisor teeth, the Class III
preparation is very difficult to perform and
often needs a labial or lingual dovetail to
gain access and aid in retention of the
restoration.

50. The distal surface of the primary canine
is a frequent site of caries attack

51. CLASS IV CAVITIES
 In these cavities caries involves the incisal
proximal angle of the anterior teeth. The
principles in the cavity preparation are the
same of the cavity preparation in
permanent teeth

52.  In regular class IV cavity preparations,
composite resin material can be used for
restoration.

53. CLASS V CAVITIES
 The Class V cavities are realized more
frequently in buccal surface of the primary
canines.
 The principles in the cavity preparation are
the same of the cavity preparation in
permanent teeth, although the depth is not
carried more than 1.5 mm.

54.  Walls of preparation converge toward
buccal surface of tooth for retention of
restoration.
 When a necessary, retentive groove can be
placed along the gingivoaxial and
occlusoaxial line angles. Use a No. 1/2
round bur at slow speed.
 Glass ionomer cement could be used
effectively for restoring these cavities.

55. Pit and fissure sealant
is a thin, plastic coating painted on the
chewing surfaces of teeth -- usually the
back teeth (the premolars and molars) --
to prevent tooth decay. The sealant
quickly bonds into the depressions and
grooves of the teeth forming a protective
shield over the enamel of each tooth.

56. Indicaations of sealant placement:
1. Deep retintive pits and fissures.
2. Stained pits and fissures with minmum
decalcification.
3. No radiographic evidence of proximal
caries.
4. Factores associated with increased caries
incidence.

57. 5. Caries free.
6. Possibility of adequate isolation.
How Are Sealants Applied?