Class i cavity prep1

Preliminary Considerations in Operative Dentistry
By
DR.SELVA

Operator positions
Direct vision
In-Direct vision

Maxillary Dentition working position
Mandibular Dentition working position

Working Position for Phantom Head Exercises

Removal of Single Typhodont tooth
Attachment of Single Typhodont tooth

Attachment of Articulator on the Jaw

Attachment of Gingival simulator on the articulator
Removal of Gingival simulator
on the articulator

The restorative materials available differ as to their
performance characteristics, cost, ease of use, aesthetic appeal,
long-term effectiveness and safety.
As a result, their suitability for the different types of clinical
situations varies. No single restorative is ideal for all indications.

Amalgam Class I restorations:
Factors to be considered:
a. Extent of pit and fissure caries.
b. Incidence of proximal surface caries.
c. Esthetics.
d. Economics.
e. Preventive procedures.
Occlusion:
use of articulating paper to register centric holding
cusps and excursive contacts so that these areas can either be
excluded or properly restored.
Local anesthesia:
given both to reduce pain and also reduction of
salivation.

Conservative cavity preparation:
is recommended to preserve the integrity of pulp and
also strength of the tooth.
Isolation of operating site:
rubber dam application is mandatory for isolation and
salivary control.
Initial cavity preparation:
Outline form, Resistance form, Retention form:
include all pits and fissures and sharp marginal outline
form is avoided.
marginal outline form for a maxillary premolar is butterfly
shape.

General principles:
a. going around the cusps to conserve the tooth structure
b. not extending the facial and lingual margins more than
half-way between central groove and cusp tips.
c. extending the outline to include fissures thereby
placing the margins on relatively smooth sound tooth structure.
d. minimal extension into the marginal ridges.
e. joining two faults when less than 0.5mm apart.
f. establishing ideal conservative depth of cavity.

Preparation sequence:
No. 245 bur with a head length of 3mm and a diameter of
0.8mm is used to prepare the class I cavity preparation.
No. 330 bur (pear shaped) is used for conservative cavity
preparation.
beginning of cavity preparation is done by performing a
punch cut over the deepest involved pit or the distal pit.
the bur should be rotating when it enters and should not
stop until its removed from tooth.
as the bur enters the tooth the depth should be kept as
1.5-2mm (1/2 – 2/3rd
the length of cutting portion of bur)
distal extension into the marginal ridge to include a
fissure or caries sometimes indicates a slight tilting of the bur
distally to prevent undermining of the marginal ridge.
premolars – distance from margin of cavity to proximal
surface must not be less than 1.6mm
molars – this distance be minimum of 2mm.

169L bur can be used for extension from pits and fissures
facially and lingually.
in larger teeth with steep cuspal inclines floor of the cavity
can follow the rise of cusps.
ideally the isthmus width be width of the bur.
minimal faciolingual width of the outline and minimal
occlusal convergence is desired.
an ideal conservative class I cavity should have a
faciolingual width of no more than 1 - 1.5mm and a depth of 1.5 -
2mm.

Final cavity preparation:
includes Removal from pulpal wall of any remaining
defective enamel, Pulp protection, Procedure for finishing
external walls, Cleaning and inspection of cavities.
Removal of any defective enamel:
No 245 bur can be used to deepen the floor of cavity to
remove caries.
a small round carbide bur or spoon excavator can be
used to remove small caries lesions.
atleast three seats of sound dentin be there periphery
to the excavated areas.
removal caries be stopped once we feel the excavated
dentin hardness is same as that of surrounding dentin.
Pulp protection:
in cavities of ideal depth no liners or bases is required.
in regions where cavity depth is of moderate zinc oxide
eugenol liner or base is preferred.
Finishing enamel walls:
its finished during the earlier steps itself so no special
steps are required.

Cavity preparation for extensive caries:
caries is extensive if the distance between infected
dentin and the pulp is judged to be less than 1mm.
here outline, resistance, retention forms are deferred
until the excavation of infected dentin is completed followed by
insertion of base.
reason is to protect the pulp as early as possible from
insult of cavity preparation.
if pulp exposure occurs during removal of caries direct
pulp capping could be tried.
here using a non-pressure flow technique to insert a
0.5-0.75mm of calcium hydroxide cement is used to cover
exposures of pulp.

Insertion of amalgam:
use an amalgam carrier to transfer amalgam to the
cavity preparation.
use a flat faced circular or elliptical condenser to
condense amalgam over the floor.
initial condenser be small followed by larger condenser
for overpacking.
each condensing stroke should overlap each other.
each condensed increment should only fill 1/3rd
– 1/2th
cavity depth.
condensation of mix be done within 21/2 – 31/2 mins.
Otherwise crystallization of amalgam be over.
Precarve burnishing:
is a form of condensation.
cavity preparations be overfilled with amalgam.
burnisher head be large enough it will contact slopes
not the margins.
this is done to remove excess mercury and also adapt
amalgam closely to cavity margins.

Carving procedure:
carving can be done immediately
sharp discoid – cleiod instruments are selected.
all carving be done with the edge of the blade
perpendicular to margins and moved parallel to margins.
part of the edge of carving blade should rest on
unprepared tooth surface adjacent to cavity margins.
after carving the outline of amalgam restoration should
reflect the contour and location of the prepared cavosurface
margins revealing a regular outline with gentle curves.
Post carve burnishing:
is the slight rubbing of the carved surface with a
burnisher of suitable size and shape to improve smoothness and
produce a satin appearance.
with precarve burnishing and now postcarve burnishing
the polishing of amalgam becomes unnecessary.

Occlusion of restoration:
after completion of procedure patient is advised not to
bite because of danger of fracturing of restoration which is weak
at this stage.
to ensure occlusion is correct its checked using
articulating paper.
while carving its advised to establish stable centric
contacts which is perpendicular to direction of occlusal load.
Finishing and Polishing procedures:
not all amalgam restorations require these procedures
but some do,
a. to complete carving procedure
b. refine the restorations
c. enhance surface texture of restorations.
This procedure is not attempted within 24hrs.

finishing and polishing of restoration should not leave a
underfilling.
after this procedure an explorer should pass from the
tooth surface to restoration without any catch or jump.
a white fused alumina or green carborundum stone is
used to correct the discrepancy.
a flame shaped finishing burs may be used to define the
grooves and fissures.
polishing procedure is initiated by coarse rubber abrasive
point at slow speed.
a high polish may be imparted using series of medium
and fine abrasive points.
instead of rubber points rubber cups with pumice could
be used.

Occlusolingual cavity preparation and restoration:
on maxillary molars its indicated when the distal pit and
distal oblique ridge and lingual fissures are connected.
some special considerations are,
a. cavity should be no wider than necessary.
b. when indicated the cavity preparation should
be done more at the expense of oblique ridge rather than
centering over the fissure.
c. especially in smaller teeth the occlusal
portion can have slight distal tilt.
these features help in strengthening the
restoration and tooth.

Preparation procedure:
using an mouth mirror indirect vision and no 245 bur
enter the distal pit. Bur should be parallel to long axis of tooth.
to preserve distal marginal ridge it may be necessary to
cut more mesial tooth structure.
slight distal inclination of bur may be necessary to
preserve the distolingual cusp.
next is preparation of the lingual surface. Tip of the bur
should be located at the gingival end of the lingual fissure. Lingual
portion should be should have an uniform depth of 1.5mm. Axial
wall should follow contour of lingual tooth structure.
mesial and distal walls of lingual portion should converge
slightly and axiopulpal line angle be rounded.
Secondary retention and resistance form:
it can be prepared using no.1/4 bur to prepare
locks on mesio and disto-axial line angles.
locks should be of depth 0.5mm into dentin.
cutting direction is bisector of the line angle.
The depth of lock should decrease in depth as it moved towards
occlusal surface.

Insertion and carving procedures:
a rigid matrix is necessary to prevent land sliding of the
restoration during condensation of lingual portion.
a tofflemire retainer is used to retain a matrix band but
this does not allow intimate adaptation of matrix to lingual portion
of tooth.
an additional step here is to cut a piece of stainless
steel matrix (0.0002 inch thick, 5/16 inch wide) that will be used
to fit in space between tooth and matrix band.
break off a round tooth pick holding it in no.110 plier.
heat a green stick compound cover this with end of a
tooth pick, now insert the tooth pick with heated compound
between tooth and matrix band.
now using a burnisher the matrix band is contoured with
firm pressure.
this was suggested by Barton.
condensation of amalgam is started from the gingival
end of lingual portion.
as the condensation is finished the matrix band is
removed using no.110 plier by slightly moving it lingually and
then occlusally.

Additional Class I preparations:
Facial pit of mandibular molar:
facial surface of a mandibular molar has often a faulty
pit and not a fissure.
cavity preparation is accomplished by a no.245 bur
positioned perpendicular to the tooth surface.
when the defect is small a no.330 or no.169L burs may
be used.
cavity depth is usually 1.5mm.
Lingual pit in maxillary incisors:
usually a no.245 bur is used in direction with orientation
of the pit which is usually apical in direction.
since the lingual enamel is thinner its recommended
depth be only 1 – 1.2mm only.
sometimes anterior maxillary teeth may develop dens –
in – dente which may also require intervention and restoration.

Occlusal pits of mandibular first premolar:
mostly because of presence large facial cusp a central
fissure is absent.
a no.245 bur is used to prepare a punch cut of 1.5-2mm
depth.
orientation of bur should be parallel to long axis of the
tooth.
this orientation preserves the small lingual cusp.
sometimes if a central fissure is present its connected by
a conventional outline.
Occlusal pits and fissures in maxillary first molar:
leaving the oblique ridge can preserve the strength of the
tooth but if required the oblique fissure must be involved.
Occlusal pit and fissures in mandibular second premolar, molar.
if mandibular second premolar has two lingual cusps the
lingual development groove may be restored.
often in mandibular molars a facial fissure may involve
the occlusal surface and may require restorations.
facial extension preparation is same as that
occlusolingual preparation in maxillary molars.

Class I Upper Premolar Class I Lower First Premolar Class I Lower Second Premolar
Class I Lower Molar Class I Upper Molar
Class I Upper Incisor

Designs of class I preparation (according to Marzouk):
a. Class I design I:
Location – occlusal surface of molars and premolars.
Indications:
caries cone into dentin no more than 1mm.
patient has low caries index.
b. Class I Design 2:
Location – occlusal surfaces of premolars and molars.
Indications:
caries cone into dentin 1mm or more from DEJ.
cavity width is more than 1/4th
interproximal width.
as a preventive measure in patients with high caries
index.

c. Class I Design 3:
Location – occlusal 1/3rd of facial and lingual surfaces of
molars and lingual surfaces of upper anterior teeth.
Indications:
a pit in aforementioned location decayed.
used as a prophylactic procedure.
involved pit in this location not connected with
other surfaces of tooth.
used in dens invagintus.
d. Class I Design 4:
Location – in molars in addition to involving their
occlusal surfaces the grooved part of facial and lingual surfaces
also involved.

Class I Design 5:
Location – in molar tooth in addition to occlusal surface
involvement most of the facial or lingual surfaces are also included
in the preparation.
Indications:
facial and lingual cusps are undermined by
backward caries
outline is not conducive to retention of
restoration
foundation for cast restoration
Class I Design 6:
Location – design included for part of the occlusal surface
of molars or premolars as well as a portion of the facial, proximal
or lingual surface in the form of a table of an entire cusp.
Indications:
portion or an entire cusp undermined by caries.
marginal ridge adjacent to an occlusal
preparation is crossed by a fissure to the facial or lingual
embrasures.
foundation for future cast restorations.

Class I Design 7:
Location – design usually involves occlusal, facial lingual
surfaces of molars and premolars.
Class I Design 8:
Location – used in molars, premolars and incisors.
Indication:
designed specifically for endodontically treated
tooth

Composite Restorations:
Introduction:
search still continues for a tooth colored material to
withstand high occlusal stresses.
newer formulation have these general features,
a. Radiopaque fillers.
b. Smaller filler particles.
c. increased amount of fillers.
d, greater strength.
e. reduced porosity
f. reduced water sorption
g. polymerization with visible light.
Advantages:
a. esthetics.
b. conservation of tooth structure.
c. improved resistance to microleakage.
d. strengthening remaining tooth structure.
e. low thermal conductivity
f. completion in one appointment.
g. economics.
h. no corrosion.

Disadv:
very technique sensitivity
higher coefficient of thermal expansion
low modulus of elasticity
biocompatability issue.
limited wear resistance.
Indications:
Class I cavities that can be properly isolated.
with minimal centric holding involvement.
Contraindications:
operating site cannot be isolated.
all occlusal contacts will be on the composite.
heavy occlusal stresses.
deep subgingival areas that are difficult to restore.
Shade matching in posterior teeth is not critical a slight shade
mismatch can aid in revaluation of the restoration.

Basic preparation designs:
a. Conventional design
b. Beveled conventional design.
c. Modified design.
Conventional design:
these are box like cavities have slightly converging
walls, flat floors, undercuts in dentin (if required).
usually this designed is not employed because it do not
strengthen the tooth structure, its employed only when an
amalgam restoration is already present or the cavity extends onto
the root surface.
Beveled conventional preparation design:
bevel is prepared using flame shaped diamonds of
approx 0.5mm width and at an angle of 45deg to external
surface.
this design is preferred when there is a requirement for
increased resistance form.
this is the preferred design for class II preparation.

More extensive preparations require reverse bevels,
skirts, bracings to enhance retention and resistance forms.
Modified design is recommended for class I preparation
where ultraconservative preparation be made.
Modified preparation:
emphasis here is more on the conserving tooth structure.
characterized by,
a. conservative removal of tooth structure.
b. establishment of beveled margins on all
cavosurface margins

Class I cavity preparation:
when restoring small pits and fissures a ultraconservative
modified preparation is recommended.
ultraconservative preparation is done using no.1/2 bur
and bevel by flame shaped diamonds.
depth of cavity is done till the caries has been removed.
for deep cavities CaOH liner and light cure GIC base is
recommended.
no.245 bur and beveled conventional preparation may be
employed when extensive preparation is entitled or a large faulty
restoration is present.
an undermined marginal ridge (enamel) can be left in
extensive preparation and can be strengthened by composite
bonding.

Conventional preparation
Beveled Conventional preparation
Modified preparation

Glass Ionomer Restorations:
early GIC lacked physical strength and wear resistance
to be utilized in occlusal restorations. Newer more heavily filled
GIC and resin modified GIC have improved strength to be utilized
with certain precautions.
they are utilized in,
a. in small to medium sized restorations protected from
occlusal forces.
b. for patients in perceived need of fluoride release.
c. for longer provisional tooth colored restorations.
d. for patients in whom restorative procedures cannot be
prolonged.
e. atraumatic restorative procedures is to performed.
f. when margins of large load bearing restorations needs
to be repaired.
Preparation outline be carefully planned to leave out margins from
occlusal contacts and not to bevel the cavosurface margins as it
may leave a thin flash of material with insufficient strength.

Minimal Invasive Dentistry (MI):
is a conservative opportunity to identify early caries risk
followed by preventive procedures designed to heal early lesions
whilst eliminating the bacterial disease.
when lesions have advanced and healing is not possible
then a minimal invasive surgical approach should control and
eliminate surface cavitation and stimulate remineralization using
a biomimetic restorative material.
the philosophy of Minimal Intervention Dentistry
combines the current knowledge of prevention, remineralization
and ion exchange adhesion.

General principles of cavity design:
until recent times cavities were designed along surgical
lines without an understanding of the action of fluoride ion and for
placement of restorative materials that were difficult to handle,
were subject to microleakage, and were often not esthetic.
also in absence of adhesion it was necessary to remove
undermined enamel defeating the purpose of preservation of
remaining tooth structure.
with better understanding of fluoride properties and
adhesion developments its possible to place restorations in
limited size cavities retaining much of tooth structure.
by today’s standard cavity design proposed by
G.V.Black is large and it was necessary to remove additional
tooth structure for ‘extension for prevention’.

New cavity classification:
prime objective here is to retain as much as natural tooth
structure as possible. Given by G.J.Mount and Hume
Three sites of carious lesion:
site 1 – pits, fissures, and enamel defects on occlusal
surface of posterior teeth and other smooth surfaces. {Class I}
site 2 – approximal enamel immediately below areas in
contact with adjacent tooth. {Class II, III, IV}
site 3 - cervical one third of crown following gingival
recession in root. {Class V}
Four sizes of carious lesions:
size 1 – minimal involvement of dentine just beyond
treatment by remineralization alone.
size 2 – moderate involvement of dentine. Following
cavity preparation, remaining enamel is sound, well supported by
dentine and not likely to fail under normal occlusal load.
size 3 – cavity is enlarged beyond moderate
involvement. Remaining tooth structure is weakened to the extent
that cusps or incisal edges are split if exposed to occlusal load.
Cavity needs to further enlarged so that the restoration can be
designed to provide support to remaining tooth structure.
size 4 – extensive caries and bulk loss of tooth structure
has already occurred.

Size 1 lesion is most commonly will be a new lesion ideal for
adhesive restorations
Size 2, 3,4 lesions may be lesions progressed to considerable
extent or may be breakdown of a earlier restoration.
Use of composite is limited by its polymerization shrinkage.
Amalgam limitation is its poor esthetic quality
GIC has excellent adhesion but lacks strength to be utilized in
marginal ridges and incisal edge.
Cavity design and preparation:
when dealing with new lesion cavity design be very
conservative, because margins can be remineralized, and cavity
extent is determined only by the extent of caries cavitaion.
on the other hand replacement of failed restoration
cavity outline will be already defined and often will be extensive.
And here most of Black’s principles hold good.

Site I , Size I, [1.1]:
usually the extent is limited and most of the fissure
system should be free of caries.
using very finest tapered diamond point (#200) enter the
fissure in region of caries attack, open the enamel to determine
the full extent of caries.
its unnecessary to remove the affected demineralized
dentin on floor of cavity but walls of cavity be free of caries.
remaining fissure system are also opened to determine
the presence of caries.
small round burs (#008 or #012) can be used to clean
walls of infected enamel.
generally there is no need to penetrate the full depth of
enamel.
Restoration:
Glass ionomer is material of choice because of fluoride
release and adhesion.
use strongest GIC available either autocure or self cure.
condition the cavity with 10% polyacrylic acid.
placement of cement in a syringe is desirable.
when using an autocure cement positive pressure with
gloved finger may be required followed by protection with a resin
sealant to prevent contamination with moisture.

when using light cure resin mosified GIC there’s no
need for finger pressure and restoration can be immediately
finished and no resin sealant required.
if the occlusal load is heavy may be lamination with
composite (sandwich restoration) can be performed.

Site I, Size 2 [ 1.2 ]:
G.V.Black classification – Class I
Preparation:
it may be a new cavity or repairing or replacement of an
old restoration.
tungsten carbide bur (#140TC) can be used to remove
old restoration, a tapered diamond or straight diamond (#160 Dia
or #156 Dia) is then used to explore the lesion.
small round burs can be used to clean the walls of the
cavity.
Restoration:
GIC is the best choice of material.
also lamination technique with composite can be
considered.

Site 1 Size 3 [ 1.3]:
when cavity reaches this size there will be extensive
undermining of atleast one cusp. It may be a new lesion of old
restoration that may be recurrent.
Preparation:
tungsten carbide burs (#140) should be used to remove
any remaining old restorations.
a small diamond straight fissure (#156) is used to
explore the lesion.
Round burs (#012 or 016) can be used to remove
infected dentin from walls of the cavity.
if it’s a new active caries it may be necessary to place
an indirect pulp capping agent then review after minimum of 12
weeks.
if cuspal strength is adequate a conventional restoration
be attempted.
if cuspal strength is weakened grooves may be placed in
cusps to strengthen the cusp with restorations.
Restoration:
of plastic direct filling materials amalgam is the choice.
most of the time teeth affected will be going in for crown.
lamination technique with resins could also be done.

Site I Size 4 [1.4] :
this is an extensive cavitated lesion there will be one or
more loss of cusps full restoration with direct restoration is
difficult.
preparation is same as for size 3 lesion.
amalgam as a restorative material could be used with
mechanical interlocks.
a full crown is the most ideal restoration.

Direct Gold Restorations:
principles of direct gold restorations must be followed
diligently for proper gold restorations.
sharp internal line angles are established for proper
starting convenient form.
Indications and contraindications:
small pits and fissures in posterior teeth and lingual
surfaces of anterior teeth.
small class V restorations.
small class III restorations.
small class II lesions in tooth not subjected to heavy
occlusal forces.
class VI lesions.
repairing of acceptable cast gold restorations.
Contraindications:
teeth with large pulp chamber.
severely periodontally weakened tooth.
handicapped patients not willing to sit for longer periods
of time.
root canal treated tooth.

Class I tooth preparation and restoration:
Design:
outline is extended to include the lesion on the
tooth and also the fissured enamel.
preparation margins are placed beyond the
pits and fissures of the tooth.
outline is kept as small as possible with
acceptance for condensation and manipulation of restorative
material.
pulpal wall is of uniform depth and established
at 0.5mm into the dentin.
small undercuts are placed in pulpal floor to
aid in beginning of condensation of gold.
a very slight cavosurface bevel is placed
about a) 30 – 40 deg of marginal metal to aid in ease of finishing
of gold.
b) to remove rough remaining enamel.
this bevel is not more than 0.2mm in width.

General shape:
outline form is similar to class I cavity preparation for
amalgam with three modifications,
a. instead of round corners here its angular corners.
b. extensions in facial and lingual grooves will end in
spear shaped form.
c. whole outline form will look more angular than
amalgam preparations.

Instrumentation:
for description a mandibular premolar is selected.
no 330 or 329 bur is used for establishing outline form
and initial depth.
a small hoe can be used to establish desired
smoothness in pulpal floor.
using a 33½ inverted bur or angle former chisel an
undercut may be given in the pulpal floor.
round burs may be used to remove any remaining
caries.
angle former or finishing bur (7802) or flame shaped
stone may be used to finish the cavosurface margins.

Restoration:
The restorative phase begins with insertion
of a pellet of E-Z Gold or gold foil.
The gold is first degassed in the alcohol flame, cooled
momentarily in air, and inserted into the preparation.
The gold is pressed to place with the nib of
a small round condenser.
Next, compaction of the gold begins with a line of
force directed against the pulpal wall.
Hand pressure is used for E-Z Gold; malleting is used
for gold foil.
the line of force is changed to a 45-degree angle to the
pulpal and respective external walls (to best compact the gold
against the internal walls).
If E-Z Gold is to be the final restoration surface,
compaction is continued until the restoration is slightly overfilled.
If gold foil is selected to veneer this restoration, then
pellets of suitable size are selected.
The pellet is degassed and carried to the preparation.
First, hand pressure compaction is used to secure the pellet
against the compacted E-Z Gold and spread it over the surface;
then mallet compaction is used.

The first step in the finishing procedure is to burnish the gold.
A flat beaver-tail burnisher is used with heavy hand
pressure to harden the surface gold.
A cleoid-discoid carver is used to continue the burnishing
process and remove excess gold on the cavosurface
margin.
After use of the cleoiddiscoid, a small round finishing bur
(No. 9004) is used to begin polishing.
It is followed by the application of flour of pumice and tin
oxide or white rouge.

Class i cavity prep1

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