This document defines and describes the clinical characteristics and principles of cavity preparation for class V cavities. Key points include: - Class V cavities are located on the gingival third of facial/lingual tooth surfaces. They have marked sensitivity and tend to spread mesially/distally near the axial angles. - The outline form is typically a rounded trapezoid in the gingival 1/3. Extensions are to the height of contour/lesion extent occlusally and subgingivally near the CEJ gingivally. - A minimum depth of 0.5mm in dentin is required for retention and uniform amalgam bulk. Internal line angles are squared except for rounded corners

3. DEFINITIO
N
Smooth surface lesions located
on the gingival third of labial,
buccal and more rarely the
lingual surfaces of all teeth.

4. Limitations:
Always simple lesions as it involves one
surface of a tooth.

5. These lesions have the
following clinical
characteristics:
11.. Caries is not only the reason ooff ccaavviittaattiioonn,,
aabbrraassiioonn aanndd eerroossiioonn mmaayy aallssoo rreessppoonnssiibbllee ffoorr
tthheeiirr ccaauussaattiioonn..

6. 2. The carious lesion usually
starts as a white or chalky line or
area near the center of the
gingival 1/3 of the labial or
buccal surfaces of teeth. If it
occurs on the lingual surface, it
is usually associated with
denture clasps.

7. 33.. MMaarrkkeedd sseennssiittiivviittyy..
44.. TTeennddeennccyy ttoo sspprreeaadd mmeessiiaallllyy aanndd ddiissttaallllyy
nneeaarr tthhee aaxxiiaall aanngglleess ooff tteeeetthh,, iitt mmaayy
ppaassss tthhee aaxxiiaall aannggllee ooff tthhee ttooootthh aanndd
uunniittee wwiitthh aa CCllaassss IIII,, IIIIII oorr IIVV
ccaavviittyy..

8. 5. Bell-crowned teeth, and
teeth with markedly convex
surfaces, are more
susceptible to this type of
caries.

9. 66.. It occurs less frequently tthhaann tthhee ootthheerr
ttyyppeess ooff ccaarriieess..

10. 7. It is usually affects multiple teeth. This
indicates that the patient has a high caries
susceptibility and requires careful extensions of
cavity outline.

11. 8-It is more frequent among old-aged patients
and is called senile caries, yet it is not
uncommon in childhood and adolescence and is
often associated with improper oral hygiene
and presence of bacterial plaque. In case of
old aged individuals, caries may be found to
extend gingivally and affect the cementum of
the root. Sensitivity will increase and the
caries may tend to recur around the margins
in cementum.

12. Application of
Principles:
The Outline Form:

13. A. General shape:
“Ferrier design, conventional or typical “
This is the most recent and accepted now.
Generally the classical Class V cavity usually
describe a trapezoidal outline with straight
margins and round corners, with the short
arm being the gingival.

14. Principles Rationale
I. OUTLINE FORM -
rounded trapezoid in
gingival 1/3.
Conforms to the tooth
shape, typical caries
location, and site of
plaque accumulation.

15. BB.. LLooccaattiioonn ooff
mmaarrggiinnss
OOcccclluussaallllyy:: IItt hhaass ttoo bbee aatt,, bbuutt nnoott
iinncclluuddiinngg tthhee hheeiigghhtt oorr jjuusstt ppaasstt tthhee
hheeiigghhtt ooff ccoonnttoouurr ooff tthhee ttooootthh oorr jjuusstt
iinncclluuddee tthhee ddeeffeeccttiivvee aarreeaa ooff tthhee ttooootthh..

16. Principles Rationale
A. Occlusal /incisal outline
is straight and parallel to
the occlusal plane .
More esthetic and
harmonious.

17. Proximally: Far enough mesially
and distally to include only the
defective and/or the decalcified
tooth tissues, yet not
encroaching on the axial angles of
the tooth, and placed just
opposite the axial angles of the
tooth.

18. Gingivally: At or ideally in
the occlusal portion of the
gingival sulcus space. In
cases of gingival recession,
the gingival margin should be
located supragingivally.

19. Resistance aanndd RReetteennttiioonn
FFoorrmmss::
a. Resistance Form:
NNoo rreessiissttaannccee ffoorrmm nneecceessssaarryy ffoorr tthheessee
pprreeppaarraattiioonn bbeeccaauussee tthheeyy aarree nnoott
ssuubbjjeecctteedd ttoo aa ddiirreecctt ffuunnccttiioonnaall llooaaddiinngg..
AA mmiinniimmuumm ddeepptt ooff 00..55 mmmm iinn ddeennttiinn iiss
rreeqquuiirreedd ffoorr aa uunniiffoorrmm bbuullkk ooff aammaallggaamm
ffoorr ssttrreennggtthh ooff tthhee mmaatteerriiaall..

20. b. Retention Form
For retention, however, as the
mandible moves in lateral excursion,
the lingual slopes of the buccal and
lingual cusps of maxillary teeth load
the buccal slopes of the buccal and
lingual cusps of mandibular teeth.

21.  Assume that we have a facial Class
V restoration in the lower molar tooth,
as illustrated in the diagram, and so
the tooth is firmly seated in bone, the
tooth structure of the crown can move
from position (1) to position (2),
making a v-shape opening at the margin
(usually the occlusal one), together
with a facial component of force
driving the restoration facially. So,
retention will be placed in the occlusal
(or incisal) and gingival walls in the
form of grooves or retentive holes.

22. If the occlusal margins approximate
the facial or lingual cusps or marginal
ridges, it is advisable to make the
occlusal walls devoid of any occlusal
grooves as this may:
i. undermine the structure of these
cusps or marginal ridges.
ii. display the restorative through the
enamel and, therefore, causes
objectionable esthetics.

23.  Although these locations are not
mandatory in premolars and in prominent,
easily cleansable molar tooth surfaces,
locating the margins apical to the height of
contour should be decided upon only after
carefully considering the cleansing ability and
plaque control technique of the patient as
well as the natural pattern of cleansing these
teeth.

24. Internal anatomy:
1. In a mesio - distal cross
section:
i. The axial wall will be smooth and
slightly curved mesiodistally, following
the curvature of the facial or lingual
surface. This is to provide resistance
to the forces of condensation and to
provide a maximal pulp protection.

25. iiii.. MMeessiiaall aanndd ddiissttaall wwaallllss,, wwiillll
aappppeeaarr ddiivveerrggeenntt oorr ffllaarree mmeessiiaallllyy
aanndd ddiissttaallllyy rreessppeeccttiivveellyy,, ggooiinngg
wwiitthh tthhee ddiirreeccttiioonn ooff eennaammeell rrooddss
ttoo ffoorrmm 9900°° ccaavvoo--ssuurrffaaccee aannggllee..
TThhiiss iiss ttoo pprroovviiddee ssttrreennggtthh ffoorr
tthhee ttooootthh aanndd tthhee aammaallggaamm
mmaarrggiinnss aanndd ttoo pprreevveenntt
uunnddeerrmmiinneedd tthhee eennaammeell wwaallllss..

26. 2. In an occluso -
gingival longitudinal
section:
i. The axial wall:
Will be seen as flat to slightly
convex occluso-gingivally depending
on the extent of the preparation
occluso-gingivally. This will provide
maximal pulp protection, while
maintaining a uniform minimum dept
of 0.5m in dentine.

27. ii. Occlusal or incisal wall:
It can appear in one of two ways:
a. Smooth and straight forming a 90°
cavo-surface angle following the
direction of enamel rods. This is to
facilitates condensation and the
adaptation of the amalgam
restoration and at the same time it
prevents undermining of enamel rods.

28. b. If the occlusal margins is located
at,the middle third of the facial or
lingual surfaces, it will be formed of
two planes; a grooved internal plane,
and is made of dentin, and an outer
amelo-dentinal plane going with the
direction of enamel rods. This will
provide a mechanical retention lock in
occlusal wall without undermining the
enamel rods.

29. iii. Gingival wall:
Also it can vary in appearance,
depending on its location, if it is
located on enamel, it requires a small
cavo-surface bevel. This will protect
the very short gingival enamel rods
from fracture during condensation
and, at the same time, it terminates
the gingival wall with its enamel wall
going with the direction of the enamel
rods, thus, eliminates the unsupported
rods.

30. In such a manner it appears with
two planes; an internal grooved
plane made of dentinand an outer
flat plane made of enamel.

31. If the gingival wall is located on
cementum of the root, it also appears
with two planes, an internal grooved
plane made of dentin and an outer
flat plane made of dentin and
cementum.

32.  All internal line aanngglleess iinn ddeennttiinnee
mmuusstt bbee ssqquuaarreedd uupp eexxcceepptt tthhoossee oonn
tthhee ccoorrnneerrss,, tthheeyy mmuusstt bbee rroouunnddeedd..
AAllssoo,, aallll ppooiinntt aanngglleess mmuusstt bbee
rroouunnddeedd.. TThhiiss iiss ttoo ffaacciilliittaattee
ccoonnddeennssaattiioonn ooff aammaallggaamm..

33. Convenience form:
The trapesiodal shape with rounded
corners and the isolation of the field
of operation using the rubber dam will
provide a better conveniency for
cavity preparation and restoration.

34. Removal of carious
dentine:
As described before.

35. FFiinniisshhiinngg ooff eennaammeell
wwaallllss aanndd mmaarrggiinnss::
 EEnnaammeell mmaarrggiinnss sshhoouulldd bbee
ssmmooootthheenneedd aanndd sshhoouulldd bbee pprroovviiddeedd
wwiitthh 9900°° ccaavvoo--ssuurrffaaccee aannggllee .. TThhee
ggiinnggiivvaall bbeevveell iiss ttoo bbee ppllaacceedd oonn tthhee
ggiinnggiivvaall wwaallllss tthhaatt aarree tteerrmmiinnaatteedd bbyy
eennaammeell aanndd nnoott wwhheerree tthhee pprreeppaarraattiioonn
tteerrmmiinnaatteess iinn cceemmeennttuumm..

36. Cavity Debridement
As described before.

37. TThhiiss FFoorrmm ooff tthhee CCaavviittyy ::
11.. MMeeeettss tthhee ggeenneerraall pprriinncciipplleess ooff
ccaavviittyy pprreeppaarraattiioonn..
22.. EExxhhiibbiittss aa pplleeaassaanntt aappppeeaarraannccee,,
aanndd
33.. IIss eeaassiieerr ttoo rreessttoorree..

38. Armamentarium
1. Rubber dam , punch , clamp forceps
and clamp no. 212.
2. Burs nos. 330 , 256 , 1/2 , 1 , 35 .
3. Hand instruments : curved chisel,
mon - angle hoe , hand excavator.

39. Instrumentation Resume
for the Class V
Preparation
1. No. 256 or 335 bur for penetration and
extension of the outline .
2. Axial wall located with the same burs.
3. If required , caries is removed with a slow
- speed round bur , as dictated by
convenience .
4. Hand excavator may be advised.
5. Gingival and incisal retention placed
with no. ¼ or ½ bur.
6. Enamel is finished and beveled with a
no. 15 Wedelstaedt chisel and 7901 or
242 bur.

41. Principles Rationale
B. Gingival outline is
straight and parallel
to the occlusal
outline.
Will allow maximum
retention to be
placed in cavity
walls if occlusal
and gingival
outlines are
parallel.

42. Principles Rationale
C. Mesial and distal
outline is straight
and parallel to the
mesial and distal
tooth outline in the
gingival 1/3.
Conforms to
the shape of the
tooth.

43. II. Extensions
Conservation of tooth structure is
the basis for all cavity preparation;
therefore, extend only far enough to
remove defective tooth structure and
create sufficient access (convenience
form) for instrumentation and
insertion of restorative material. In
addition, access for finishing and
maintenance of the restoration must
be provided.

44. Principles Rationale
A. Circumscribe
1. Decay, decalcification,
and defects.
2. Enamel unsupported by
dentin.
3. Eroded, abraded areas.
4. Existing restorations
Eliminates weak or
defective tooth
structure so that
margins of the
restoration will
terminate on sound
tooth structure
(extension for
prevention).

45. Principles Rationale
BB.. OOcccclluussoo--ggiinnggiivvaall
eexxtteennssiioonnss
11.. OOcccclluussaallllyy ttoo tthhee hheeiigghhtt ooff
ccoonnttoouurr ((oorr ttoo tthhee oocccclluussaall
eexxtteenntt ooff tthhee lleessiioonn))
22.. GGiinnggiivvaallllyy ttoo tthhee ggiinnggiivvaall
eexxtteenntt ooff tthhee lleessiioonn
((ffrreeqquueennttllyy ssuubbggiinnggiivvaallllyy
nneeaarr tthhee CC..EE..JJ..))
Provides
sufficient access
for
instrumentation
and
condensation
and for
prevention.

46. Principles Rationale
C. Mesio-distal
extention is to the
line angles of the
tooth (or to the
extent of the lesion
mesially and
distally).
Extention for
prevention, more
esthetic and
harmonious.

47. III. RESISTANCE/RETENTION FORM
Principles Rationale
A. Depth
1. 0.5 mm in dentin
2. 1-1.25 mm (may vary
slightly depending on
size of tooth,
thickness of enamel
and extensions);
occlusally 1.5 – 1.75
mm depth may be
required to achieve
0.5 mm in dentin.
A minimum depth is
required to provide
retention and uniform
bulk of amalgam for
strength of material –
further tooth reduction
is unnecessary and may
result in pulpal
encroachment or
sensitivity.

48. Principles Rationale
B. Axial Wall
1. Smooth
2. Slightly curved
mesiodistally.
3. Straight or slightly curved
occlusogingivally depending
on the extent of the
preparation
occlusogingivally.
Easier to adapt
amalgam to smooth
walls provides
resistance to forces
of condensation and
provides maximumal
pulpal protection
while maintaining
uniform minimum
depth (0.5 mm in
dentin).

49. Principles Rationale
C. MMeessiiaall aanndd ddiissttaall
wwaallllss
11.. SSmmooootthh aanndd ssttrraaiigghhtt
oocccclluussooggiinnggiivvaallllyy..
Facilitates
condensation,
adaption.

50. Principles Rationale
2. Flare mesially
and distally
respectively to
form 900 metal
margins).
provides strength for
the tooth and
amalgam margins
(prevents
undermined enamel
and provides a 700 -
900 amalgam margin)
– Resistance form.

51. Principles Rationale
D. Occlusal or incisal
wall
1. Smoothly and
straight mesiodistally.
Facilitates
condensation,
adaption.

52. Principles Rationale
2. Forms a 900
cavosurface angle
(occlusal wall is
parallel to the
enamel rods – 900 to
a tangent to the
external surface).
Prevents
undermining of
enamel rods,
assists in providing
retention by
opposing the
gingival wall which
forms an acute
gingivocavosurface
angle.

53. Principles Rationale
3. Occlusal retention
– two undercuts .5
mm deep in the
dentin of the
occlusal wall at the
occluso-axial line
angle (one mesially
and one distally)
Provides
retention – a
mechanical lock
in occlusal wall
without
undermining
enamel rods.

54. Principles Rationale
E. Gingival wall
1. Smooth and
straight
mesiodistally.
Facilitates
condensation,
adaption.

55. Principles Rationale
2. Gingival
retention – an
acute axio-gingival
angle
(700).
Provides
mechanical lock
to retain the
amalgam (primary
retention).

56. Principles Rationale
3. If terminated on
enamel requires a
small cavosurface
bevel.
A small enamel
bevel protects the
very short gingival
enamel rods from
fracture during
condensation, and
eliminates
unsupported
rods.

57. Principles Rationale
IV. CAVITY FINISH
AA.. LLiinnee AAnngglleess
11.. AAxxiiaall lliinnee aanngglleess
aarree wweellll ddeeffiinneedd
aanndd ccoonnffoorrmm ttoo tthhee
ccoonnffiigguurraattiioonn ooff
tthhee ccaavvoossuurrffaaccee
oouuttlliinnee ffoorrmm
((iinntteerrnnaall oouuttlliinnee))..
Increase
retention

58. Principles Rationale
2. Mesio – occlusal,
mesio-gingival, disto-occlusal,
and disto-gingival
walls form
rounded line angles.
Facilitates
condensatio
n.

59. Principles Rationale
B. Point angles are
rounded
Facilitates
condensation

60. Principles Rationale
CC.. CCaavvoossuurrffaaccee
mmaarrggiinnss
11.. WWeellll ddeeffiinneedd
22.. SSttrroonngg ((ssoouunndd))
Well defined, sound
cavosurfaces are
required to resist
condensation forces
and produce a well
adapted, durable tooth
restoration margin
which will resist
plaqueaccumulation
and prevent recurrent
caries.

61. Principles Rationale
D. Cleanliness
- the cavity must
be free of
moisture and
debris.
a clean, dry cavity
preparation will allow
more intimate
adaptation of
amalgam to the cavity
walls. An amalgam
which is placed in a
dry environment will
have superior
physical properties
to one placed in a
moist environment.

62. Principles Rationale
V. TISSUE/DAM PRESERVATION
A. The rubber
dam is
intact.
damage of the
dam will cause
leakage and loss
of isolation
(moisture
contamination).

63. Principles Rationale
B. Surrounding
enamel, dentin,
and cementum are
preserved
undamaged.
conserves
natural tooth
structure
eliminates post-operative
pain
inflammation.

64. Principles Rationale
C. Soft tissue undamaged.