Fundamentals of cavity preparation /certified fixed orthodontic courses by Indian dental academy

FUNDAMENTALS OF CAVITY
PREPARATION

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.com

CONTENTS
INTRODUCTION
CAVITY PREPARATION-
DEFINITION
HISTORY
OBJECTIVES OF CAVITY
PREPARATION
FACTORS AFFECTING CAVITY
PREPARATION


CLASSIFICATION
G V BLACK
MODIFICATIONS OF G V BLACK
GRAHAM J MOUNT
VIMAL K SIKRI
OPERATING SITE
STAGES OF CAVITY PREPARATION
INITIAL STAGE
STEP:1 OUTLINE FORM AND INITIAL
DEPTH
STEP:2 PRIMARY RESISTANCE FORM
STEP:3 PRIMARY RETENTION FORM
STEP:4 CONVENIENCE FORM

FINAL STAGE
STEP:5 REMOVAL OF REMAINING ENAMEL
OR INFECTED DENTIN

STEP:6 PULP PROTECTION

STEP:7 SECONDARY RESISTANCE AND
RETENTION FORM

STEP:8 FINISHING EXTERNAL WALLS OF
CAVITY PREPARATION

STEP:9 CLEANING INSPECTING VARNISHING
AND CONDITIONING


CAVITY PREPARTION- MOUNT’S
CLASSIFICATION

SITE 1- SIZE 1, 2, 3, 4
SITE 2- SIZE 1, 2, 3, 4
SITE 3- SIZE 1, 2, 3, 4

RELATIONSHIP BETWEEN
BLACK’S & MOUNT’S
CLASSIFICATION
CONCLUSION
REFERENCES

INTRODUCTION

CAVITY: Refers to a defect in enamel, or
enamel & dentin, resulting from pathologic
process- DENTAL CARIES
Once caries process invaded-Frank
cavitation
Effective treatment for preventing further
progress - complete removal of affected
area

Cavity preparation accomplished in an
orderly sequence

meant to serve as a guide

not as hard-&-fast list of directives

rationale for development of cavity
preparation

inter-related steps & mutual support

CAVITY PREPARATION
defined as the mechanical alteration of a
defective injured or diseased tooth in
order to best receive a restorative
material which will re-establish a healthy
state for the tooth including esthetic
corrections, along with normal form and
function.


Performance of dental surgical
procedures, require to expose carious
lesion, permit removal of affected dentin
& enamel as to contribute to biologically
& mechanically sound restoration

Mechanical preparation &/or chemical
treatment of remaining tooth structure,
which enables to accommodate
restorative material, without incurring
mechanical or biological failure

HISTORY
Archaeological evidence of dental
treatment from 5000 BC
1800 early drills by hand
1955 Page-chayes handpiece-first belt
driven angle handpiece
1957 Borden airotor handpiece-first
clinical air-turbine handpiece
airmotor, electric micromotor, straight
handpiece, right-angled handpiece
air abrasion, lasers - latest

9th century cavities prepared for inlays
cavity preparation techniques known for
centuries
19th century Hamelton Jameson first
emphasized the organized cavity
preparation
removal of soft & infected dentin-hand
instruments
sterilize dentinal surface
retention form- dentinal buttons
Charles E Woodbury- labial margin
preparation in harmony with lines of
refraction of labial surface

Henry A Time - slant technique

Extension for Prevention - Marshall Ebb &
G V Black

Charles E Woodbury, E K Wedelstaedt,
Walton I Ferrier , George Hollenback

1930 G V Black- systemic approach to cavity
preparation

Simon -6th classification

1998 G J Mount classification

OBJECTIVES OF CAVITY
PREPARATION
remove all defects-protection to pulp
locate margins of restorations as
conservative as possible
form cavity- withstand under force of
mastication tooth/restoration
allow esthetic & functional placement
of restoration


repair a tooth after destruction from a carious
lesion

replacement and repair of restoration with
serious defects

restore form & function
• fractured teeth, congenital malformation, esthetic
purpose


FACTORS AFFECTING CAVITY
PREPARATION
 GENERAL FACTORS  PATIENTS FACTOR

diagnosis economic status
prevention age
interception choice of material
preservation
restoration


CLASSIFICATION

G V Black’s classification

Modifications of G V Black’s classification

Graham J Mount

Vimal K Sikri

G V BLACKS CLASSIFICATION
 Firstclassification
 universally accepted
 based on type of treatment & areas
involved
 controlled by number of factors
• to gain access & visibility
• removal of affected dentin from floor
• room for restorative material
• extension for prevention
• mech. Interlocking retentive designs
• cavosurface margins self cleaning areas

G V BLACK’S CLASSIFICATION
CLASS I

pit & fissure

occlusal surfaces - premolars & molars

lingual surfaces of maxillary incisors


CLASS II

proximal surfaces of posterior
teeth


CLASS III

proximal surfaces of anterior
teeth do not involve the incisal
edge


CLASS IV

proximal surfaces of anterior teeth
involve incisal edge


CLASS V

gingival third of facial or lingual
surfaces


CLASS VI

 incisal edge of anterior / occlusal
cusps heights of posterior teeth

 Simon - later added


 Concepts of Black controversial &
debatable

 with new adhesive restorative materials


G J MOUNT CLASSIFICATION

 Designed to simplify identification of
lesions


site size
Minimum Moderate Enlarged Extensive
1 2 3 4

Pit/fissure
1
1.1 1.2 1.3 1.4
Contact area
2
2.1 2.2 2.3 2.4
Cervical
3
3.1 3.2 3.3 3.4


VIMAL K SIKRI CLASSIFICATION
 class I
div 1 - pits & fissures of occlusal surfaces
div 2 - B & L pits of postr & antr

 class II
div 1- one proximal surface of postr
div 2 - both proximal surfaces of postr

 class III
div 1 - one proximal surface of antr
div 2 - both proximal surfaces of antr

Class IV

div 1 - cervical one-third of labial & lingual
div 2 - labial & lingual line angles of all teeth

 class V
div 1 - labial of antr than cervical one-third
div 2 - lingual of antr than pits & cervical 1/3

 class VI
div 1 - incisal tips
div 2 - occlusal cusp tips

OPERATING SITE

moist- free environment

isolation

protecting soft tissues

margins limited to
supragingival sulcus


STAGES OF CAVITY PREPARATION

 INITIAL STAGE

 FINAL STAGE


INITIAL CAVITY PREPARATION

 mechanical alterations of tooth extended to sound
tooth structure, in all directions, while adhering to
specific, limited pulpal depth

 cavity walls designed to retain restoration &
resist fracture.


INITIAL CAVITY PFREPARATION

 exacavation of remaining, infected dentin

 removal of old restorative materials

 pulp protection

 additional cavity designs - minimize fracture

 finishing preparation walls

 cleaning, inspecting varnishing

INITIAL STAGE
 STEPS INVOLVED

STEP:1 outline form and initial depth

STEP:2 primary resistance form

STEP:3 primary retention form

STEP:4 convenience form


 FINAL STAGE

STEP:5 removal of remaining enamel or infected
dentin

STEP:6 pulp protection

STEP:7 secondary resistance and retention
form

STEP:8 finishing external walls of cavity preparation

STEP:9 cleaning inspecting varnishing and
conditioning

INITIAL CAVITY PREPARATION

extension & initial design of external walls
of preparation at a specific limited depth,
provide access to cavity/ defect reach sound
tooth structure, resist fracture of restoration/
tooth,forces directed in long axis of tooth &
retain restoration

no deeper than 0.2mm into dentin - pit &
fissure

0.2mm - 0.8mm - smooth
www.indiandentalacademy.com suface

OUTLINE FORM & INITIAL DEPTH

placing cavity margins in positions will
occupy in final preparations except
enamel walls & margins

preparing initial depth of 0.2 - 0.8mm
pulpally of DEJ


Is the locations that the peripheries of
completed tooth prepn.will occupy on tooth
surfaces

is the perimeter of tooth prepn.in width,
length & depth of dimension


PRINCIPLES

friable / weakened enamel removed
all faults included
margins placed in position- good finishing
of margins of restoration
extension for prevention
sufficient enamel & dentin to locate the
pulpal & axial walls or prepn.surfaces
within 0.5mm from DEJ

FACTORS
extent of carious lesion, defect/ faulty
restorations

esthetic considerations

occlusal relationships

adjacent tooth structure

cavosurface margin

FEATURES
preserving cuspal strength

preserving marginal ridge strength

minimizing f-l extensions

enameloplasty

connecting to close faults

restricting depth

PIT & FISSURE CAVITIES

 CONTROLLED BY THREE FACTORS

 extent of enamel carious lesion
 extensions along fissures- sound smooth
margin
 limited bur depth, pulpal depth- 1.5-
2mm & maxi depth into dentin-0.2mm


RULES
 unsupported/ weaken enamel
 avoid terminating eminences
 extension of primary groove- capping of cusp
 all fissures
 restrict pulpal depth
 as conservative as possible
 no: 245 bur- 2mm- f/l walls & depth 1.5mm


p & f less than 50% of pulpal floor-
removed in final stage
 greater than 50% of pulpal floor, deepened,
0.2mm into dentin
 actual depth varies- depends on thickness
of enamel & steepness of cuspal incline
 outline varies -depending on anatomic
form of tooth, pit & fissures on occlusal
surfaces

 butterfly type preparation

 flare & MD width of embrassures

 occlusion & masticatory forces

 caries index & oral hygiene

 age of patient

 creating more convex restorations

SMOOTH SURFACE LESIONS

 two locations

proximal surface

gingival portion of facial & lingual
surface


PROXIMAL SURFACE
unsupported/ weakened enamel

avoid terminating eminences

extend margins for sufficient access

restrict axial wall pulpal depth maxi- 0.2-0.8mm
into dentin

not remove dentin caries deeper pulpally than
0.5mm from DEJ

minimum clearance 0.5mm between gingival
margin & adjacent tooth

 Class II preparations
 placement of margins of pit & fissures
 for inlays – dovetail on the occlusal surface

 Class III Preparation
 incisal margin of sound enamel -contact area
not extended incisally


GINGIVAL PORTION OF FACIAL AND
LINGUAL AREA
 class v
 extension mesially, gingivally, distally &
occlusally (incisally) limited
 bur depth no deeper than 0.8- 1.25mm
pulpally from original tooth surface
 axial pulpal depth at occlusal wall-
provides 0.5mm into dentin


RESTRICTED & INCREASED
EXTENSIONS
RESTRICTED
 proximal contours & root proximity
 esthetic requirements
 tooth preparations for composite restorations

INCREASED
 advanced age of the patient
 need for additional retention & resistance
form
 adjust tooth contours

conventional
 removal of unsupported enamel
width-md/bl-atleast 1.5mm
pulpally & axially –atleast 1.5mm
facial & lingual margins involve entire f/l
groove –to avoid feather-edged marginal
amalgam
mortise shape –each wall & floor –flat plane,
meeting each other at definite line & point
angles
proximal portion- box type / truncated cone
isthmus- not exceed 1/3rd intercuspal distance
atleast 1.5mm
sweeping curves- proximal & occlusal walls
meet

cavity preparation for – class I amalgam
outline form


class II cavity preparation for amalgam


Class III Cavity Preparation for Amalgam:


Class V Cavity Preparation for Amalgam:


modifications
 Extension for prevention- not apply
 conservative approach
 not extend f & l more than midway between
central grooves & cusp tips
 enameloplasty on terminal ends of shallow
fissures
 proximal portion- only a unilateral inverted
truncated cone on functional side of marginal
angles
 gingival margin located occlusal to ht of
contour
 isthmus- not exceed 1/4 intercuspal distance
 sweeping curves-exaggerated

Tooth colored restorations
 Extension for prevention - not apply
 adhesive resto.mate.revolusionized the
concept of cavity design
 conserve more tooth structure
 floor routinely not placed in dentin- depends
on extend & depth of lesion
 bevel on cavosurface margin
 contact area - should be maintained
 butt joint marginal configuration - for
retention & bevelled the margin


Cast gold restorations
 Gingival to occlusal divergence of walls- 2-5
degree taper on each wall
 taper minimum in shallow cavities
 more in deeper cavities

 bevelling
 to obtain lapp joint at cavosurface margin
 20- 30 degree
 increases marginal adaptation


PRIMARY RESISTANCE FORM

defined as the shape & placement of the
cavity walls best enables both restorations
& the tooth to withstand, without fracture ,
masticatory forces delivered in long axis of
tooth
architectural form given to a tooth , which
enables both restoration & remaining tooth
to resist structural failure from occlusal
loading stresses

PRINCIPLES
 utilize box shape with a flat floor
 restrict extension of external walls
 slight rounding of internal line angles - reduce
stress
 cap weak cusps & envelope / include enough
weakened tooth
 provide enough thickness of restorative material
- prevent fracture
 major principle is that restoration should
rest on flat sound tooth structure,
perpendicular to occlusal forces directed
parallel to the long axis of tooth

FEATURES
 relatively flat floors
 box shape
 includes weakened tooth structures
 preservation of cusps & marginal ridges
 rounded internal line angles
 adequative thickness of restorative materials
 seats on sound dentin peripheral to excavation of
infected dentin
 reduction of cusps for capping


 Stress patterns of teeth
 use floors at right angles to direction of
loading- to avoid shear stress
 walls parallel
 box / cone / inverted truncated cone
 definite line & point angles
 Amalgam & cast gold - approx.1.5mm
 porcelain - 2mm for inlays
1.5mm for crowns
composite no criteria for resistance form


 class I
flat floor large resto.depth increased with
increase in diameter
 class II
pulpal line angle more rounded- MOD
 class III
cavity extended lingually as close to incisal edge
as possible
 class V
functn. Cusp & fossa reln.dictates stress patterns
 grooves provide resistance to certain degree


PRIMARY RENTENTION FORM
 shape / form of prepared cavity that resists
displacement / removal of restoration from
tipping/ lifting forces
 defined as a form given to tooth
prepn.,especially its detailed anatomy &
general shape, which enables the restoration,
that will accommodate, to avoid being lodged
by masticatory loading
 intra coronal-
inside a cavity prepn,within the tooth
 extra coronal
on prepn.surface, replacing reduced
ext.tooth surface

PRINCIPLES
 related to restorative materials used
 retention form vary from material
 higher degree of parallelism bet.opposing
walls
 inverted truncated cones or undercuts
 dovetail
 elastic deformation of dentin


CONVENIENCE FORM
shape/ form of cavity that provide adequate
observation & accessibility
ease of operation in preparing & restoring
the cavity
• modifications in tooth prepn.
Flaring
lingual / labial access
• instrument modifications
contra-angling
bayoneting
• separation
wedging of teeth

 Cavosuface angles

• amalgam -90 degree
• inlay beveled- 20-40 degree
• margins located on self-cleansing areas
• smooth curves


FINAL CAVITY PREPARATION
Removal of any remaining enamel pit / fissure
&/ or infected dentin & / old restorative
material, if indicated.

 it is elimination of any infected carious
tooth structure / faulty restoration within
the tooth after initial cavity preparation


 caries left in pulpal / axial floor excavated

 0.75-1mm of dentin cover the pulp

 when affects esthetically

 weakened tooth- given retention

 secondary caries , if present

 periphery of old resto.mate. not intact


PULP PROTECTION
 pulpal injury, due to
heat generated while cutting
resto.mat.with good thermal conductivity
chemicals from resto.mate.
Galvanic currents
microleakage
 placement of cavity liners / bases/varnish–
not a step
 it is the step in adapting the preparation for
receiving the final restorative material
 mechanical, chemical & thermal protection
of pulp

SECONDARY RESISTANCE & RETENTION
FORM

 TWO TYPES

MECHANICAL FEATURES

CAVITY WALL CONDITIONING


 Mechanical features
retention locks
grooves & coves
skirts
beveled enamel margins
pins amalgapins
slots
 Cavity wall conditioning features
enamel, dentinal wall conditioning
for bonded restorations


Grooves-indicated in cast resto., prepared in wall of
proximal box in DEJ
depth equal to width
placed at AB & AL line angles
parallel or slightly divergent

etching- micromechanical retention
slots- prepared in dentin
increase surface area
more convergent walls
1-1.5mm deep box type

locks-in proximal box of class II
amalgam restorations
0.2-0.3mm wide & 0.5mm deep into dentin

skirts-in cast restorations
extensions of proximal box
margins beveled

Amalgam- retention enhanced
parallel walls & flat pulpal floor / gingival floors
occlusal convergence of walls [class II]
occlusal convergence & dovetail
slots in gingival floor
proximal retention- AF & AL locks

cast gold restorations
axial retention in form of locking & friction in
micro-irregularities
parallelism / 2-5 degreedivergence
occlusal extension- increase in area
lateral retention - dovetail / pinholes & pot holes


Tooth colored restorations
acid conditioning
retentive cavity preparation
physico-chemical retention
Posts

direct gold
class III- undercut at point angles
class IV grooves along gingivopulpal &
incisal pulpal


FINISHING THE EXTERNAL WALLS OF
CAVITY PREPARATION
 further development when indicated, of a
specific cavosurface design & degree of
smoothness that produces maximum
effectiveness of restorative material being use
 to create best marginal seal bet.resto.mate.&
tooth
 to afford smooth marginal jn
 provide maxi.strength of both tooth & resto.


Features

design of cavosurface margin

degree of smoothness of wall


Cleaning, inspecting, varnishing &
conditioning.

Removing debris, chips

dry the cavity


G J MOUNT’S CLASSIFICATION
3 SITES
SITE 1: pit fissure & enamel defects on
occlusal of postr or other smooth surface

SITE 2: approximal enamel immede. below
areas in contact with adjacent teeth

SITE 3: cervical 1/3 of crown / following
gingival recession, exposed root

4 SIZES

SIZE 1: minimal involvement of dentin-
just beyond treatment by
remineralization

SIZE 2: moderate involvement of dentin

SIZE 3: cavity enlarged beyond
moderate

SIZE 4: unnecessary to remove affected,
dentin-floor but walls clean

Site 1 lesion:
commences in fissure on occlusal surface
of postr
pits on lingual upper antr
buccal surface of lower molar
lingual extension of DO groove of upper
molars
erosion / attrition on occlusal surface of
postr
incisal edges of antr


size 1: small defect in one section of pit &
fissure
often with placement of fissure on the
reminder of fissure system
size 2: moderate with most fissures
involved / replacement of an existing
black class I restoration
size 3: larger requires protection for one
or more cusps in design
size 4: extensive with one or more cusps
already missing


1.1
 lesion on occlusal surface of postr
 limited, other sections free from caries
 other fissures may be deep / convoluted-
subjected to later attack

 unnecessary to remove affected,
demineralised dentin-floor but walls
clean

 margins should be sound & free of
microcracks & loose enamel rods

1.2
G V Black I
care not to extend the cavity

 unnecessary to remove affected dentin-
floor but walls clean

 occlusal
enamel should be retained, thro’
unsupported, margins are sound

 no microcracks
 remaining fissure explored

1.3
G V Black class I
 larger requires protection for one or
more cusps in design
 extensive undermining or breakdown of
atleast one cusp with possibility of split
developing at the base
 care not to remove affected dentin-floor
but walls clean
 indirect pulp capping
 all remaining cusps- need protection
from occlusal load

1.4
G V Black class II

 extensiveloss of one or more cusps
 mostly molars


SITE 2
proximal surface of antr / postr immediately
below contact area

 size 1: minimal involvement of dentin-
healing by remineralization

 size 2: extensive involvement of dentin
with marginal ridge weakened /
breakdown, still remaining tooth structure
to support restoration


 size3: postr tooth- involvment of dentin
with a split at the base of a cusp
need to protect one / more cuspal inclines
from occlusal load
antr proximal caries with loss ofsupport for
incisal corner

 size4: complete loss atleast one cusp from
postr / incisal edge


2.1
no equivalent in G V Black
classification minimal involvement of
dentin- healing by remineralization

3 different approaches- position in reln
to marginal ridge / lesion in adj.tooth
internal occlusal fossa / tunnel approach
slot cavity
proximal


Internal Occlusal Fossa / Tunnel
Preparation
 enamel lesion atleast 2.5mm apical to
crest of marginal ridge
 thro’ occlusal fossa just medial to
marginal ridge
 create funnel shape access cavity
 No specific retentive designs
 marginal ridge cracked- removal of MR -
cavity becomes 2.2


Slot cavity
 closeto MR
 too weak to be maintained
 access gained thro’ MR
 more in antr

 lesinthro’ MR - small box form cavity-
not extended beyond demineralised
enamel
 maintain contact with adj.tooth


Proximal approach
if adj.tooth already in site 2- size 3/4
prepared in it with missing proximal box

direct access thro’ proximal
good access & visibility
occlusal remains intact
MR maintained


2.2
G V Black classII [postr], class III [antr]

 if amalgam

 if composite


2.3
G V Black class III [antr], class II
[postr]
 antr- bevels to enhance retention
 in postr identify- split at the base of a
cusp
 cusp that is split- modify cavity outline
 support for one-half of cusp / single cusp
 but all 4 cusps protected
 maintainence of full ht - atleast one cusp
indicate original occlusal ht

2.4
G V Black class IV [antr], class II [postr]
 antr-loss of major section of incisal half
of crown
 unsupported enamel supported

 margins trimmed to smooth finish
 postr- retain cusps based on sound dentin


Site 3
 gingival 1/3 of crown or exposed root
surface
 on open surfaces[f/l] in reln to contours
of gingi.tissue / interproximally, below
contact area
 caries enamel margin around full
circumference- occlusal margin in
enamel & gingi.margin in dentin
 root surface caries
 gingival recession


3.1
G V Black class V

 caries found in gingi. Margin
 high caries risk
 poor oral hygiene
 no instrumentation for erosion


3.2
G V Black class V

 more extensive


3.3
G V Black class V

 rootsurface caries
 gingival recession


3.4
G V Black class V

 two / more caries around cervical marginof
any tooth


RELATIONSHIP BETWEEN BLACK’S &
MOUNT’S CLASSIFICATION
Site 1- size 1, 2, 3, & 4
 pit fissure caries
 on occlusal postr/ any simple enamel defect/
smooth surface of any tooth
 black class I- size 1 - could not carried, no
suitable resto. Material
 blacks begins with site 1, size 2 [1.2]


Site 2, size 1, 2, 3 & 4
 approximal lesions [contact area]
 antr / postr- immediately below contact
area
 black class II
 no equivalent of size 1
begins with 2.2
 blackclass III
 no equivalent site 1
begins 2.2
 black class IV
classified as 2.4

Site 3, size 1, 2, 3, 4
 gingival 1/3 of crown
 black class V
 erosion / abrasion
3.1, 3.2, 3.3, 3.4


CONCLUSION
Better understanding of caries process
improved knowledge of function of fluoride
limit size of cavity

retaining atleast some demineralised enamel
& dentin
heal thro’ remineralization
retain more natural tooth structure


REFERENCES
 Sturdevant’s Art & Science Of Operative Dentistry;
Theodore M Roberson, Harald O Heyman, Edward J
Swift Jr – 4TH Edition, Mosby Publications

 Operative Dentistry, Modern Theory & Practice; M A
Marzouk, A L Simonton, R D Gross – 1st Edition,
IshiyakuEuroamerica, Inc. Publishers, Tokyo, St. Louis,
All India Publishers & Distributors, Chennai

 Textbook of Operative Dentistry; Vimal K Sikri – 1st
Edition, CBS Publishers & Distributors

 Principle & Practice of Operative Dentistry; Charbeneau
– 2nd Edition, KM Varghese Company

 Fundamentals of Operative Dentistry: A Contemporary
Approach; James A Summit, J William Robbins,
Richard S Schwartz, Jose Dos Santor – 2nd edition,
Quintessence Publishing co.Inc.

 Operative Dentistry; Gilmore, Lund, Bales, Vernetti – 4th
Edition, B I Publications Pvt.Ltd

 Operative Dentistry; McGehee, True, Inskippp – 4th
Edition, M C Books, Inc.

 Textbook of Operative Dentistry; Lloyd Baum, Ralph W
Phillips, Melvin R Lund – 3rd Edition, B Saunders
Company

 Hampson’s Textbook of Operative Dentistry; E L
Hampson – 4th Edition

 Preservation & Restoration Of Tooth Structure, G J
Mount, w R Hume 1st Edition, Mosby Publications


Fundamentals of cavity preparation /certified fixed orthodontic courses by Indian dental academy

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