CURRENT CONCEPTS IN CLASSIFICATION,

INDICATION, PRINCIPLES AND PROCEDURES OF

CAVITY PREPARATION WITH RESPECT TO ADHESIVE

RESTORATIONS

Introduction

Macrodentistry is the density that has been practiced for

centuries with the conventional concept of “Extension for

prevention” or cutting for immunity. A patient who has been

assessed as having a high caries risk is immediately worked on

and preventive restorations have been given.

Microdentistry

In the past few years the emerging techniques of

operative density dedicated to minimal invasion and minimal

sacrifice of sound tooth structure have been explored and

documented and they have become part of the mainstream

dentistry. As new techniques emerge and are adapted into

dental disciplines, the usual intent and purpose of the original

technology often change in the course of adaptation.

Microdentistry, the dental science of diagnosing,

intercepting and treating dental decay on the microscopic level

is now emerging as an operative tool in science-based

microdentistry. The ultimate goal is prevention of extension

and restriction with conviction.

Historical aspects

1. Historical aspects of G.V. Blacks – Concept of cavity

preparation

a. Introduction

When Black defined the parameters for his classification,

the cavity designs were controlled by a number of factors,

many of which no longer apply. Caries was rampant and the

significance of fluoride was not understood. There were

limitations in the available instruments for cavity preparation

as well as in the selection of restorative materials. The five

categories of carious lesion were related to the site of the

lesion and to the nature of the intended restoration, but they

did not take into account the increasing dimensions of a cavity

nor the complexity of the method of restoration.

b. G. V. Black’s classification

Class I

All pit and fissure restorations are class I and they are

assigned to the three groups as follows

1. Restorations on occlusal surface of premolars and molars.

2. Restorations on occlusal two thirds of facial and lingual

surfaces of molars.

3. Restorations on lingual surface of maxillary incisions.

Class II

Restorations on proximal surfaces of posterior teeth

Class III

Restorations on proximal surface of class III which do

not involve the incision angle

Class IV

Restorations on proximal surface of anterior teeth which

involve incisal edge

Class V

Restorations on gingival third of the facial or lingual

surfaces of all teeth

Class VI

Restorations on the incisal edge of anterior teeth or the

occlusal cusp heights of posterior teeth

c. Materials

Amalgam, Direct filling gold, Cast metal

d. Principles

To remove tooth structure to gain access and visibility.

To remove all trace of affected dentine from the floor of

the cavity.

To make room for the insertion of the restorative material

itself.

To provide mechanical interlocking retentive designs.

To extend the cavity to self-cleansing areas to avoid

recurrent caries.

The result was that, by today’s standards, all such

restorations were large. In his designs, Black showed

commendable respect for remaining tooth structure as well as

occlusal and proximal anatomy but it was necessary to

sacrifice relatively extensive areas of enamel to achieve his

goals.

e. Earlier concepts of conservation

1. Occlusal convergence

It aids in retention as well as conversation of occlusal

tooth structure. This design of cavity preparation exposes

minimal amount of restorative material to occlusal loading.

2. Reverse curve

3. Double pulpal floor

Here one level of pulpal floor is at ideal depth (1.5mm

for amalgam) and others will be at a deeper level as dictated by

the pulpal extent of decay. The deeper part of pulpal floor is

called ledge. It can be circumferential, interrupted or opposing.

iv. Preservation of oblique ridge

Oblique ridge is included in cavity preparation only when

(i) undermined by caries, (ii) directly affected by caries and

(iii) when less than 0.5mm.

v. Enameloplasty

If less than one third of enamel depth is involved by

carried the fissure may be removed by enamel plaster without

extending the tooth preparation. Enamel is reshaped into a

saucer form so that the area becomes cleanable, finishable and

allows conservative placement of preparation margins.

vi. Prophylactic odontotomy

Proposed by Hyart in 1924. It is characterized by

minimally preparing and filling with amalgam, developmental,

structural, imperfections of the enamel, such as pits and

fissures, to prevent caries originating in these sites.

The demineralization and remineralization cycle

Demineralization

The mineral component of enamel, dentine and cementum

is hydroxyapatite, Ca 10(PO4)6(OH)4 in a neutral

environment, hydroxyapatite is in equilibrium with the

local aqueous environment, which is saturated with Ca 2+

and PO43 ions.

Hydroxyapatite is reactive to hydrogen ions at pH 5.5

(the critical pH for hydroxyapatite) and below. Hydrogen

preferentially with the phosphate groups in the aqueous

environment immediately adjacent to the crystal surface.

The process can be thought of as conversion of PO 43 to

HPO42 by the addition of hydrogen and the hydrogen

being buffered at the same time.

The HPO42 ions is then not able to contribute to the

normal hydroxyapatite equilibrium because it contains

PO4, not HPO4 and the hydroxyapatite crystal therefore

dissolves. This is termed demineralization.

Remineralization

The demineralization process can be severed if the pH is

neutral and there are sufficient Ca 2+ and PO43 ions in the

immediate environment.

Either the apatite dissolution products can reach

neutrality by buffering or the Ca 2+ and PO43 ions in

saliva can inhibit the process of dissolution through the

common ion effect.

This enables rebuilding of partly dissolved apatite

crystals and is termed remineralization.

This interaction can be greatly enhanced by the presence

of fluoride ion at the reaction site.

Acid reaction with apatite at the tooth surface

Following eruption there is a process of continuing

mineralization of enamel from salivary calcium and

phosphate.

Initially, enamel apatite contains many carbonate and

magnesium ions, which are highly soluble in even mild

acidic conditions. However, there is a rapid and extensive

exchange of hydroxyl and fluoride ions as the magnesium

and carbonate are dissolved, leading to a more mature

enamel with a greater resistance to acid ion challenge.

This level of maturity or acid resistance can be greatly

enhanced by the presence of fluoride.

As the pH decreases the acid ions react, principally with

the phosphates in saliva and plaque (or calculus) until the

critical pH for dissolution of hydroxyapatite is reached at

approximately pH 5.5 – 5.2.

Further decrease in pH results in progressive interaction

of the acid ions with the phosphate groups of

hydroxyapatite, causing partial or full dissolution the

surface crystallite.

Stored fluoride released in this process reacts with the

Ca2+ and HPO42 ion breakdown products, forming

fluorapatite or fluoride – enriched apatite.

If the pH decreases further below 4.5, which is critical

pH for fluorapatite dissolution even fluorapatite will then

dissolve.

If acid ions are neutralized and the Ca 2+ and HPO42 ions

are retained the reverse process of remineralization

occur.

Factors contributing to maintenance of de- and

remineralization

Saliva with its buffering capacity

Ca2+ and PO4 levels

Fluoride application

Oral clearance of proteins &

Glycoproteins

Buffering and

Remineralization potential

Diet + plaque acids

Decreased salivary flow Decreased buffering

capacity and oral

clearance rate

Acidic saliva erosive acids

Protective factors

Destabilizing factors

To detect accurately the prime cause of an imbalance in a

particular patient. It is essential to be familiar with the precise

nature of each of the factors and the activity that occurs on the

tooth surface.

The various factors are:

1. Bacterial flora – Streptococcus mutans

2. Plaque retention – contact areas, overhangs, over

contours, pits and fissures, sticky foods.

3. Thickness of plaque

4. Salivary buffers

5. Fluorides

6. Frequency of carbohydrate intake

Effect of plaque on pH of saliva

Fermentable carbohydrate entering the oral environment

go into solution in saliva and become available to plaque

microbes 2 – 4 point drop in pH at tooth surface. Amount of

pH drop depends on plaque thickness, number and type of

plaque bacteria, efficiency of salivary buffering.

Recovery to normal resting pH takes from 20 minutes

average to several hours for those with increased caries

susceptibility.

Acids from carbohydrate fermentation are weak organic

acids and will cause only chronic low grade caries.

Other sources of acids are from

Carbonated drinks

Citrous fruits

Gastric reflux

Protective factors

Natural factors – role of saliva

Diet factors

- Increased fat in diet decreased plaque attachment

- Milk products like cheese

- Fibrous foods increased chewing increased

flow of saliva

Saliva and its protective factors

Saliva plays an important role in protecting teeth against

acid challenge. Normal salivary flow = 3ml/min, in xerostomia

– it is 0.3ml/min increased caries risk.

Factors decreasing salivary flow

Physiologic

- age – decreased secretory cells

- sleep

Xerostomia

- Sjogren’s syndrome

Radiation therapy

- Xerostomia

- Cervical caries due to decreased salivary flow

Medications

- Anticholinergics

- Antihypertensives

- Antidepressants

Unstimulated saliva contains little bicarbonate buffer

with fewer calcium ions and more phosphate ions.

Reflex stimulation of saliva by chewing or through the

presence of acidic foods can increase the flow by a factor of

more than 10. Bicarbonate buffer concentration increased 60

times upon stimulation. Calcium ions increased but PO 4 ions

do not increased in proportion to flow rate reduction of

maximum salivary flow to less than 0.7ml/min increased

caries risk.

Salivary protective factors

1. Ca and PO4 ions

It is usually the saliva is supersasturated when the enamel

apatite is at neutral pH. PO 4 ions also provides a significant

buffering capacity at resting pH and in early stage of acidic

challenge.

2. Pellicle

Origin from saliva. Protects against acid challenge. Acts

as a barrier to diffusion of acid ions into the tooth. Also may

inhibit mineralization of apatite to form supersaturated levels

of Ca and PO 4 in saliva.

3. In stimulated saliva

Good HCO3 buffering system

4. Salivary flow and oral clearance rate

Influence removal of food debris and microorganisms

5. Fluoride content of saliva is low

0.03 ppm or 1.6 mol/litre but still contribute to

protection and repair of tooth minimal.

Effect of fluoride on enamel

In acidic environment, fluoride ion reacts with free Ca ++

and HPO42 ions forming fluorapatite crystals. Fluoride

replaced hydroxyl ions since the ionic radii of fluoride

(1.36A0) and OH (1.4A0) are similar. Fluorapatite is less

soluble because of better submit stacking. It gets dissolved at

pH of 4.5. In tooth structure, its concentration is as high as

2500 – 4000 ppm. Daily consumption of water contain fluoride

at 1mg/lit increased caries resistance.

Fluoride

Fluorapatite (less soluble)

Inhibits bacterial metabolism

Decreased demineralization

Increased remineralization

Decreased plaque formation

Decreased wettability of tooth structure

Increased concentration of fluorides stored as CaF 2

around apatite crystals heavy remineralization at surface

lesions.

Effect on established lesions

1. Contribute to remineralization of incipient enamel caries.

2. Partly remineralize carious dentin and therefore slows

down assets carious process in the cavitated lesion.

3. Remineralize root surface lesions to the extent that they

may not need a restoration.

Topical fluoride is more effective in inhibiting smooth

surface caries and in aiding remineralization of enamel, dentin

and cementum. Less effective in fissures. Daily application of

topical fluoride to demineralzie root surfaces over a period of

2 – 4 months leads to significant hardening of exposed

dentin. Deep and extensive root caries can be hardened with in

the same period of time but required a higher concentration of

fluoride.

Level of remineralization

Enamel

Till actual cavitation has not occurred.

Only if some crystal structure is present.

Dentin

Early stages of development of lesion.

Till the collagen matrix has not collapsed.

Breakdown within dentin can be divided into two

identifiable zones.

1. Infected dentine

Surface layer closest to oral environment.

Heavily infected with bacteria.

Collagen matrix collapsed.

Stain red with basic Fuschindye.

Dark brown / black in color

Soft consistency can be readily removed with sharp

excavator.

Not remineralizable.

2. Affected dentine

In the advancing front of caries following course of

dentinal tubules.

Colorless, relatively soft

Basic structure of collagen matrix present and intact

Sterile with very few pioneer bacteria

Can be remineralized to some degree

Regarded as precarious, not removed and left to be healed

Also not removed entirely as pulp immediately subjacent

to approaching caries will be initiated and inflamed by

presence of bacterial toxins and mechanical exposure will

lead to pulpal death.

Potential for remineralization

Once the cavitation has occurred, the infected layer is

removed and the lesion is completely isolated from the oral

environment with an adhesive restoration, which will prevent

microleakage. Remaining pioneer bacteria left in the affected

dentin will become dormant and pulpal irritation will cease.

The deep affected layer that had been demineralized will

be subject to remineralization because collagen matrix is still

intact.

In the past zinc oxide and eugenol paste was used as a

sealant because of its antibacterial properties, but now glass

ionomer is preferred as it completely seals cavity and releases

fluoride, Ca++, phosphate ions thus encouraging

remineralization and healing of dentin.

Demineralized enamel and dentin can be remineralized

but not cavitated lesions.

White spot lesions on the visible surfaces of tooth can be

remineralized.

Radiographic assessment

Minimal depth of detectable lesion on the radiograph is

about 500m.

60% of teeth with proximal radiographic lesion on the

outer half of dentin are non-cavitated and hence should

be remineralized than restored.

Classification of approximal radiolucencies assessing

caries based on radiographs.

E1 - outer half of enamel

E2 - inner half of enamel

D1 - outer third of dentin

D2 - middle third of dentin

D3 - inner third of dentin

E0 - no carious lesion

Dentin is divided into three zones, as it enables more

conservation criteria to be established.

Using this minimally invasive technique, restorations are

not indicated until lesion has extended to D 2 region.

Disadvantages

overlapping proximal contacts

lengthening of image wrong idea on depth of lesion

2-D image

superficial remineralization not seen

fracture of one lingual cusp is seen as radiolucency of

proximal cavity.

1. In case of incipient or minimal lesion involving limited

pit and fissures preventive resin restoration (sealant

alone / sealant and filled resin).

2. Decalcified appearance of pits and fissures indicative of

incipient / minimal caries Sandwich preventive resin

restoration (Glass ionomer liner, filler resin and sealant).

3. Involvement of adjacent pit and fissure enamel with

possible minimal involvement of underlying enamel and

dentin glass ionomer PRR (GIC liner, GIC restorative

and sealant)

4. No minimal undermining isolated pits and fissured. No

radiographic / clinical evidence of interproximal caries

but possible radiographic evidence of occlusal caries

sealant amalgam PRR (Amalgam in isolated pits and

fissures without extension for prevention and sealant).

New cavity classification

The understanding of the effect of fluoride on the

demineralization – remineralization cycle as well as the advent

of true long term, adhesion with restorative materials, has

made it possible to reconsider the classification of carious

lesions and cavity designs first rationalized by G.V. Black.

Mount’s classification

The three sites of carious lesions

Site 1

Pits, fissures and enamel defects on occlusal surfaces of

posterior teeth or other smooth surfaces

Site 2

Approximal enamel immediately below areas in contact

with adjacent teeth

Site 3

The cervical one-third of the crown or following gingival

recession, the exposed root

The four sizes of carious lesions

Regardless of site or origin of lesion

Size 1

Minimal involvement of dentin just beyond treatment by

remineralization alone

Size 2

Moderate involvement of dentin. Following cavity

preparation, remaining enamel is sound, well supported by

dentin and not likely to fail under normal occlusal load

Size 3

The cavity is enlarged beyond moderate involvement.

Remaining tooth structure is weakened to the extent that cusps

or incisal edges are split or are likely to fail if exposed to

occlusal load. The cavity needs to be 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.

Minimal Moderate Enlarged Extensive

Size 1 2 3 4

Site

Pit/fissure 1.1 1.2 1.3 1.4

1

Contact area 2.1 2.2 2.3 2.4

2

Cervical 3.1 3.2 3.3 3.4

3

Black’s classification did not allow for size 1 lesion in

either site 1 or site 2 because of absence of adhesive

restorative materials.

In the past, most restorative treatment was due to carries

(dacay) and the term cavity was used to describe a carious

lesion in a tooth that had progressed to the point that part of

the tooth structure had been destroyed. Therefore, when the

affected tooth was repaired the cutting or preparation of

remaining tooth structure was referred to as a cavity

preparation.

Nowadays many indications for treatment for teeth are

not due to caries and therefore the preparation of the tooth is

no longer referred to as cavity preparation but as tooth

preparation.

Tooth preparation is defined as the mechanical alteration

of defective, injured or diseased tooth to best receive a

restorative material that will reestablish a healthy state for the

tooth, including esthetic corrections where indicated, along

with normal form and function.

Earlier Black advocated the principle of extension for

prevention i.e. in tooth preparations for smooth-surface caries,

the restoration should be extended to areas that are normally

self-cleansing to prevent reoccurrence of caries and to include

full length of enamel fissures in pit and fissure cavities.

This extension for prevention has been reduced to

restriction with conviction by treatments that conserve tooth

structure, therefore restored teeth are stronger and more

resistant to fracture. Such treatments are enameloplasty, pit

and fissure sealants, preventive resins and conservative

composite restoration.

Earlier preventive measures included prophylactic

odontonomy i.e. developmental, structural imperfections of

enamel, such as pits and fissures were minimally prepared and

filled with amalgam to prevent caries originating in these sites.

Guiding principles of adhesive cavities

Black’s concept of extension for prevention is no longer

valid. The current paradigm is rather prevention of

extension.

Cavity outline form cavity outline internal and

external, is only dictated by the extent of the carried.

Once caries dentin is removed, no further removal of

tooth substance is required.

Resistance

Resistance of both tooth and restorative material to resist

fracture.

Loose and fragile enamel rods should be moved, but

unsupported tooth structure may conserved and weakened

tooth may be reforced by the bonded restoration.

90-degree cavosurface angles are given for GIC.

Long level design for composite.

If the margin is under functional loading the margin in

that area might have a cavosurface angle that approaches

60 to 80 degrees.

Occlusal bevels should not be utilized for posterior

composite preparations.

After caries removal, the internal cavity features rounded

characteristics, straight internal walls and defined line

angles are no longer required for adhesive materials.

Retention

Macroretentive interlocking designs have changed to

retention by means of micromechanical (interlocking of

resin tags into the retentive pattern of erched tooth

tissues), submicromechanical (hybrid layer, horizontal

branching between dentin tubules, surface roughness of

tubules) and chemical adhesion (ion-exchange layer of

glass ionomers).

Placement of a bevel increase by the potential surface

area for retention by a more transverse cut of enamel

prisms (enhanced etch pattern) and by extending the

surface area of the preparation available for bending.

Cervical margins should only be beveled if the margin is

well above the cementoenamel junction.

Convenience

The concept of convenience continues to apply, as the

clinician should have access to the work area for efficient

execution of techniques and manipulation of the

materials.

The concept of self cleansing areas has been discarded

and removal of all affected dentine from the axial wall of

the cavity is strictly contra-indicated because of the

potential for remineralization and healing.

Cavity preparations

Site 1 lesions

Fissures on occlusal surface of posterior teeth.

Pits on lingual of upper anterior teeth

Pits on buccal surface of lower molars

Pits on lingual extension of distal occlusal groove of

upper molars

Size 1

Small defect in one section of a pit or fissure, it is of ten

combined with placement of a fissure seal on remainder of the

fissure system.

Size 2

Moderate size lesion with most fissures involved or

replacement of an existing Black class 1 restoration.

Size 3

Larger lesion requiring incorporation of protection for

one or more cusps in the design.

Size 4

Extensive lesion with one or more cusps already missing

Size 1 and size 2

No equivalent in G.V. Black classification

Preparation

Extent limited, most of fissure system free of caries.

Other sections of fissures deep and convoluted and subject to

later attack require protection through sealing at this time.

Fine tapered diamond point

Enter fissure till the extent of lesion

Small round burs

It is used to clean walls of infected enamel and dentin. It

is unnecessary to remove the affected, demineralized dentin on

the floor of the cavity, but it is essential the walls are

completely clean and free of caries. Enamel margins should be

sound and free of microcracks and loose enamel rods.

Restoration – advantages

GIC

Adhesion fluoride release

Use strongest cement

High powder liquid ration to ensure optimal physical

properties

Condition cavity will 10% polyacrylic acid to ensure

optimal adhesion

Placement of cement with a syringe is desirable to ensure

positive adaptation into the depths of cavity.

Autocure cement Resin modified glass ionomer

cement

Apply positive pressure using lightly

lubricated gloved finger as matrix.

After seating, seal the cement with

resin sealant to maintain water balance

Trim occlusion with round steel bur at

low speed with no air water spray

Seal again

No matrix required. No need to seal

as long as it has been light

activated for 40 secs.

Restoration polished immediately

after light activation at

intermediate high speed under air-

water spray

Erosion, abrasion lesions on occlusal surface of

posteriors and incisal edges of anteriors not instruments as free

of caries and smooth.

Restoration lamination technique

Conditioning

Autocure GIC on dentin as base

Both enamel resin build up

Conditioning

Resin modified GIC

Only enamel etching

Chemical union between GIC and composite

Site 1 site 2

Preparation

New cavity or replace old restoration

Tapered or parallel sided diamond bur to explore

extent

Round burs to remove caries from walls

Affected dentin on floor left

Occlusal enamel retained, even though it is unsupported,

so long the margin are sound and there are no microcraks.

Restoration

GIC as it can reinforce undermined enamel and it can be

laminated as required with composite resin if occlusal

load is excessive.

Composite resin should not be used alone because of its

shrinkage on curing with the consequent risk of micro-

leakage. Lamination over GIC provides a combination of

two materials sufficient to restore the physical properties

of tooth very close to original conditions.

Site 1 site 3

Preparation

Do not remove all affected dentin from floor of cavity to

avoid problems arising from pulp exposure. Indirect pulp

capping may be required, seal with GIC for 12 weeks and then

reassess.

Temporary restoration

Old New

On affected layer give ZnOE GIC

Advantages

Provide adequate seal.

Eugenol kill residual

bacteria and diffuse through

dentin into pulp space to

inhibit inflammation and

pain.

Advantages

Relatively insoluble

Sufficiently strong to

withstand occlusal load

Easily placed and easy to

remove

Release fluoride which has

potential to kill bacteria in

dentin and promotes

remineralization of adjacent

hard tissues with exchange

of Ca, PO 4 and fluoride ions

between GIC and

demineralized dentin.

Disadvantages

Limited mechanical strength

Limited durability for longer

term as it degrades through

hydrolyses

Advocated by Masster 40 years

ago used ZnOE as provisional

restoration. It was antibacterial

and isolated lesion from

bacterial invasion, pulp

recovered from inflammation but

remineralization did not occur.

GIC adheres to enamel and

dentin through an ion

exchange mechanism, thus

eliminating microleakage.

It adheres to collagen of

demineralized dentin on

cavity floor through either

hydrogen bonding or

metallic-ion bridging. In

absence of bacterial activity

the pulpal inflammation

subsided.

In the presence of water

from the positive dentinal

fluid flow that follows, there

will be Ca, PO 4 and fluoride

ion exchanged between glass

ionomer and demineralized

dentin. Further ions will be

available from pulpal fluid

and dentin will remineralize.

GIC has relatively low

fracture resistance, therefore

provide a layer of 3mm if

soft demineralized dentin

remains on floor.

Reinspected after 3 months

(12 weeks) and laminated

with another material like

composite which as high

strength, satisfactory wear

resistance and adhesion to

sound well supported

enamel.

Next, check the remaining cusps

1. If a cusp has a column of sound dentine providing

adequate support for enamel and there is more than one

half of medially facing cuspal incline still present, it can

remain standing without protection.

2. If a cusp is undermined and medial incline is subject to

occlusal load, it requires protection otherwise it will

develop a split at the base.

Therefore retentive elements such as grooves and ditches

are placed in remaining sound dentin to ensure that a

restoration is soundly locked in.

Restoration

Plastic material – amalgam

Advantages

Easier to build and cause occlusal anatomy

Wear factor similar to natural tooth

Superior resistance to flexure and is better able to

provide positive protection to weakened tooth structure

Make more satisfactory base for crown which will be

required at later stage.

GIC liner 0.5mm thick to minimize thermal exchange

greater thickness of base will reduce bulk of restorative mat.

Carefully modify the length of opposing working cusp to

minimize the depth of intercupation between two teeth and

reducing splitting stresses on restored tooth and eliminating

undesirable contacts during lateral excursions.

Site 1 site 4

Preparation

Extensive on molar. Complete loss of one or more cusps.

Restorative material amalgam. Later full or three quarter

crown will be required. Preparation same as 1:3 and indirect

pulp capping may be required.

Restoration

If amalgam used mechanical interlocks like ditches

and grooves placed in gingival area.

GIC base 0.5mm thick as thermal barrier.

Place matrix to compensate for missing enamel wall.

Build up.

Site 2 lesions

Proximal surface of anterior or posterior teeth beginning

immediately below contact area

Size 1

Minimum dentin involvement which has reached a point

beyond healing through remineralization identified by

radiography or transillumination.

Size 2

More extensive involvement of dentin with marginal

ridge weakened or broken down but still sufficient tooth

structure remaining to support the restoration

Size 3

On posterior tooth considerable involvement of

dentin with split at the base of cusp or at least the potential for

split – need to protect one or more cuspal inclines from

occlusal load.

On anterior tooth extensive proximal caries with loss

of support for incisal corner which will be deeply undermined.

Size 4

Complete loss of at least one cusp from a posterior teeth

or loss of part of incisal edge of an anterior tooth as a result of

either caries or trauma

Site 2 size 1

No equivalent in G.V. Black classification

Lesion commences in enamel

Extends facially and lingually in elliptical shape

controlled by extent of contact area

Does not involve contact area

Does not undermine marginal ridge or incisal corner

If prism structure of enamel has not collapsed it can be

remineralized

a. Internal occlusal fossa (Tunnel) – 1 s t approach

When enamel lesion is at least 2.5mm apical to crest of

marginal ridge

Entry through the occlusal fossa just medial to marginal

ridge

Preparation

Posterior teeth

Enter occlusal fossa just medial to marginal ridge aiming

towards expected carious lesion

Lean bur facially and lingually to form funnel shaped

access cavity. Triangular in outline with apex towards

central occlusal fossa and base along medial aspect of

marginal ridge.

Remove carious dentin with round burs

Removal of all affected dentin on axial wall is

unnecessary, if there is risk of exposing pulp

If enamel demineralized and not cavitated – it is left

alone to be supported and remineralized through cement

If enamel cavitated and needs to be broken down, short

length of metal matrix placed interproximally and

wedged. Small round burs and hand instruments used to

complete cavity.

Anterior teeth

Access through labial or lingual (esthetic) side

Labial approach only if crowding and overlapping present

Enter medial to marginal ridge

Restoration

GIC both anterior and posterior

Lamination with composite if the load bearing area of

restoration involves occlusal support against the opposing

tooth.

If using type II resin modified GIC should be

radioopaque mixed at high P.L ratio use mylar strip as

matrix for good proximal contour.

Place cement in 2 increments using a syringe.

Tamp the first increment into the depths of the cavity

using a small dry plastic sponge.

If enamel cavitated, some excess cement should be

extruded between matrix and tooth.

Add the second increment and tamp again to ensure firm

adaptation to entire cavity wall.

Light activate the cement from several directions for to

see.

Trim restoration apply surface glase to seal

If autocure used

It should be sealed to maintain water balanced as soon as

the matrix is removed because these cements remain

susceptible to water loss and water uptake for several hours

after placement. Cover restoration with low viscosity, single

component, light activated resin bond.

Adjust occlusion with a round bur at slow spread with no

air-water spray. Add further resin bond to ensure adequate

isolation of the cement form oral environment, finally light

activate the resin.

If lamination with composite required

Remove GIC to a thickness of 2mm

Expose entire enamel wall.

Bevel the enamel as required

Acid etch for 15 seconds both enamel and autocure GIC

Wash, apply enamel bonding agent and build composite.

Site 2 size 1 (slot cavity) – 2 nd approach

When carious lesion commence high on the proximal

surface of posterior teeth leaving less than 2.5mm of the

marginal ridge occluso-gingivlly or its may be cracked or

otherwise very seek.

Preparation

Lesion approached from marginal ridge and small box

shaped cavity prepared not extending beyond

demineralized enamel.

Contact may be maintained on adjacent tooth on facial,

lingual margin or both.

Do not extend medially more than half-way through the

marginal ridge.

Restoration

Resin modified GIC or lamination with composite mylar

strip used as matrix.

Size 2 size 1 (Proximal approach) – 3 rd approach

When preparation of a larger site 2 size 3 or 4 cavity will

allow good access and visibility to the proximal surface of an

adjacent tooth with a site 2, size 1 lesion no need to involve

marginal ridge.

Preparation

Entry by small tapered diamond cylinder bur. Access

to lesion and entry angle will be dictated and controlled

to some degree by the cavity in the adjacent tooth but as

the caries is progressing into the dentine in an apical

direction and normally doesn’t undermine marginal ridge

at this size, there is no problem removing all infected

layer without involving marginal ridge.

Round bur is used to clean along circumference of walls.

Restoration

Restorative material should be radiopaque. Restoration

not under load and esthetics not a problem, type II to autocure

cement is used. With resin modified GIC, there may be

problems with access for activating light.

Site 2, size 2 – G. V. Black – Class II (posterior), Class III

(anterior)

Marginal ridge and proximal surface broken down.

Sound enamel, particularly fro the gingival floor, is not

removed just because it is undermined following removal

of caries. The enamel at the gingival is not under occlusal

load and can be retained, thus keeping the restoration

margin out of gingival crevice.

No need for dovetail retentive element final proximal

outline form will often be curved rather than dovetail and

generation of sharp line and point angles is

contraindicated because the angles complicate the

placement of restorative material and lead to stress

concentration.

Weekend enamel around the proximal box, particularly

along the gingival floor, can be supported and reinforced

with GIC, but facial and lingual enamel must be soundly

based on dentine if it is to be a significant factor in

retention and prevention of microleakage when placing a

composite resin restoration.

In anterior teeth, if no fissure involved, prepare a slot.

Do not remove entire contact area.

Unsupported enamel will be maintained through adhesion

with restoration.

Preparation

Begin just medial to marginal ridge using very fine

diamond point (# 200). Remove caries with small round bur

(008 to 012).

Leave affected dentin on axial wall to be remineralized.

Walls need no be free of contact with adjacent tooth.

Retain as much gingival enamel as possible even if it is

undermined and weekend. Because this enamel is not

subjected to occlusal load, it can be supported and

reinforced through adhesion with GIC.

Weekend and unsupported enamel should not be involved

in adhesion using composite resin with the etching

technique because it is likely to fail under setting

contraction of resin.

If amalgam is used for restoration, prepare retentive

features and involve occlusal fissures.

Restoration

If with amalgam

a. Base of GIV 0.5mm thick as thermal insulators.

b. Cavity and lining covered by a single, application of

copal varnish which will wash out over a short period of

time and this will allow deposition of corrosion products

to seal interface.

c. Resin or GI amalgam bonding agent over lining and

cavity which will provide some degree of adhesion

between amalgam and tooth structure.

If GIC restoration - used alone or laminated with

composite resin in posterior teeth where occlusal load is too

great for GIC to remain without support.

Site 2, size 3 – Black’s class III and II

For anterior teeth

Extensive proximal caries with loss of support for incisal

corner which will be deeply undermined.

Preparation

Retain all possible enamel even though unsupported by

dentin.

Don’t remove affected dentin from axial wall.

Remove friable enamel rods.

No dovetail preparation

Bevel as required to enhance retention with composite

resin.

Undermined enamel should be supported with GIC and it

will then provide degree of retention to composite resin.

If composite resin alone to be used enamel must be well

supported with sound dentin around the full

circumferences.

Pins contraindicated as

1. Difficult to disguise under esthetic restoration, shadow

casted through restoration.

2. Lead to microleakage in future.

Restoration

If there is satisfactory enamel margin around full

circumference of the cavity, it will be sufficient to cover

and protect the exposed dentine with GIC as dentin

substitute. The microchemical attachment of composite

resin to enamel through acid etching will then retain

restoration.

Cavity extensive and gingival enamel is insufficient or

too week, begin restoration with GIC as dentin substitute

(strongest GIC with high powder liquid ratio).

As soon as cement is set, cut back to expose enamel

margins and make room for composite resin. Rebuild the

contact area in composite but leave gingival extension of

proximal box in GIC.

For posterior teeth

Considerable involvement of dentin with split at base of

cusp or at least potential for splitting.

Split

Generally the result of frequent loading on sharp angled,

medially facing cusp inclines, often through working side

contacts in lateral excursions. Patient will report pain on

pressure or possibly following release of pressure.

If 2.2 cavity, there was sufficient strength in both buccal

and lingual walls to support the restoration, whereas in 2.3 it is

necessary to rely on the restoration to protect the remaining

tooth structure.

Preparation

Material of choice for this type is amalgam due to large

size of cavity. Both tooth structure and most restorative

materials, apart from gold are relatively brittle. They are

strong enough in bulk to withstand masticatory stress but in

their section will fail easily. Therefore modification to cavity

design should aim at

1. Provision of restorative material in bulk to provide

protection for the tooth structure which is now regarded

as weak.

2. Remove weakened tooth structure from undue occlusal

load.

The combined effect can be developed by leaving the

facial and lingual walls out from the gingival floor, in a

straight line to or just beyond the tip of the cusp.

Eliminate the medially facing inclines form the occlusal

end of the cusp and at the same time retaining as much as

possible of the original cusp height.

A non working cusp does not require great deal of

support so it is sufficient to provide approximately

0.5mm of coverage.

Working cusp will be subject to heavy load and therefore

required up to 2.01mm of coverage depending on type of

occlusion.

By turning the walls outwards in this fashion restorative

material can be built over the cusp with a cavosar face

margin close to 90 0 without compromising strength of the

cusp at gingival end.

Use # 168 diamond bur for this preparation.

Retentive grooves and ditches can be prepared for

amalgam.

Restoration

Amalgam material of choice with a lining of GIC (low

powder content) for thermal protection shape buccal and

lingual contour before carving occlusal surface. Correct

occlusion.

If GIC used it is laminated with composite normally not

used as GIC is too brittle; composite resin is flexible and the

enamel to which it would gain adhesion is unsupported and

brittle.

Site 2 size 4 for anterior teeth – G.V. Black’s class IV

Incisal half of the crown lost

Occlusal load not heavy

Preparation

Access achieved by # 168 or #156 bur unsupported

enamel can be supported to some degree with GIC, so trim the

margins to a smooth finish. Remove caries around wall only

and leave affected dentin on the axial wall.

In traumatic fracture protect expose dentin with GIC.

Bevel enamel margins and place composite restoration.

Restoration

GIC laminated with composite.

GIC high powder content reinforced or resin modified.

If gingival margin has no enamel left or is too weak to

allow retention with composite resin, let it be covered by

GIC.

Bevel the enamel.

Begin with hybrid resin on the lingual for optimum

strength and laminate with microfilm resin on the labial

to enhance esthetics.

In posterior teeth

Entire cusp has failed, either from extensive carious

attack or as a result of a split and it generally leaves at

least one margin close to the epithelial attachment.

Preparation

The cusps are undermined or split they should be

protected as in the design for a #2.3 cavity. Retention must be

developed in the gingival floor wherever possible using ditches

and grooves.

Restoration

Amalgam is the material of choice. GIC is not used as it

requires support from the remaining tooth structure. Composite

not used as sound enamel for adhesion is not available.

For bicuspids lamination technique can be used as

occlusal load is not excessive.

Site 3 size 1

Occurring in the gingival one-third of the crown or on the

exposed root surface of any tooth.

G. V. Black classification – Class V

Preparation

Remove the carious dentine only, using small round burs

(# 008 or #012).

Do not remove demineralized enamel

If GIC to be used the state of enamel is not important

because the continuing fluoride release will encourage

remineralization. If the cavity is to be restored with

composite resin, the outline will need to be extended to

reach sound, fully mineralized enamel which can be

safely etched to provide microchemical attachment.

No instrumentation is required for the restoration of an

erosion lesion.

Control of gingival seepage and haemorrhage with an

application of trichcoroacetic acid.

Gingival retraction cord.

Restoration

The material of choice is a type II.1 restorative aesthetic

glass-ionomer, either autocure or resin modified and a

gingival margin in dentine can be laminated with

composite resin.

Clean cavity with a brief scrub of pumice and water on a

small rubber up to remove the pellicle.

Then condition with 10% polyacrylic acid for 10 seconds,

washed thoroughly and dry lightly when using light

activated resin modified cement, contour and polish

immediately with a very fine diamonds under an air-water

spray. Apply a thin coat of the appropriate glaze to seal

any remaining surface porosities and scratches.

When using an autocure glass-ionomer with a high

powder: liquid ratio, cover the cement with a layer of a

single component, very low viscosity resin enamel bond

to stabilize the cement and avoid water uptake or water

loss. Complete the contour and polish after 1 week, if

after a few days, the aesthetics of the glass-ionomer is

unsatisfactory laminate with a composite resin.

Site 3, size 2

More extensive than 3.1, treatment same

Site 3, size 3

Approximal lesions that have developed either as primary

root surface caries after gingival recession or recurrent caries

at the gingival margin of an existing restoration.

Treatment same.

Site 3, size 4

Combination of two or more cavities around the cervical

margin of any tooth. Example lone-standing lower canine

where a labial # 3.2 lesion is joined by another # 3.3 lesion on

the distal side possibly even another # 3.2 on the lingual side.

Restoration

The greatest problem will be to construct suitable matrix

to facilitate placement of the cement. One technique is to

cut a soft tin matrix to shape and then cut a small hole in

an appropriate to syringe the cement.

An alternative technique is to use a resin-modified

cement and build the restoration incrementally with

carefully light curing at each stage.

Pit and fissure sealants

Definition

Pit and fissure sealants are cements or resin materials

which are introduced into unprepared occlusal pit and fissures

of caries susceptible teeth forming a mechanical and physical

protective layer against the action of acid producing bacteria

and their substrate.

Mode of action

1. Mechanical sealing of pits and fissures with acid resistant

material.

2. Annulling the preferring habitat of streptococcus mutants

and lactobacillus.

3. Allowing better cleaning of pits and fissures.

Selection of patient

Child with extensive caries on primary teeth is indicated

for sealing all the 1 s t permanent molars. Medically

compromised, physically / mentally retarded children fall

under special category for sealant placement.

Tooth selection

Child with occlusal caries on one of the 1 s t permanent

molars – seal the rest of the 1 s t permanent molars.

Child with more than one carious first permanent molar –

seal the 2nd permanent molars as soon as they erupt.

Diagnosis – it is important to know which tooth is sealed.

Visual and tactile – they still play an important role

despite an improvement in technology.

Drawbacks

Cavitations can be diagnosed by binding of explorer.

Mechanical binding of explorer in pits and fissures may be due

to non-carious causes like

Shape of fissure

Sharpness of probe

Force of application

Injudicious exploring causes cavitations

Probing may vary from one operator to other

Detecting fissure caries by probing is only 24% efficient

(Penning).

Criteria for diagnosis

Softening at the base of fissure

Opacity surrounding the fissure

Softened enamel that may flake away during probing

Treatment plan based on exploring

I. Caries free surface (no explorer wedging)

Well coalesced self cleansing

- Observe and recall 6 months

Stained fissure

- Observe and recall

Stained minimal opacity

- Sealant placement

II. Caries free (explorer wedging) sealant placement

Materials

1. Resins

The 1 s t use of sealant was an unfilled resin BIS-GMA but

because of its viscous nature it was discontinued. Later

diluents like methylmethacrylate made resin effective aw

sealants. Two types of polymerization – chemical and light

cured.

Differences

Light cured Chemical cure

1. Working time – 10-20

seconds

2. No mixing is needed, no

voids formation

3. Polymerization starts until

light activated

1. 1 – 2 minutes

2. Voids can be incorporated

3. Starts immediately after

mixing

Sealants differ from restorative resins by the amount of

filler added which increase the wear resistance.

Examples

Filled - Kerr sealants

Unfilled - Contact seal

Chemically - Concise white (3M) Delton

Light cured - Prisma shield Helio seal

Light cure resin show better retention rates in comparison

to unfilled / filled chemically cure sealants.

Laser curing of sealants was introduced by Powell in

1989.

Laser curing of visible light activated sealant shows

increased tensile bond strength of resin material and

increased resistance to caries.

Sealants with fluorides

It was perceived that addition of fluorides to sealants

may improve caries resistance. But no study documented the

beneficial effect with fluoride sealants.

Fluoridated sealants release fluoride to the greatest extent

in the 1 s t 24 hours after mixing and the release falls

sharply on the 2 nd day and slowly decreased later (Garcia

Goday) caries reduction of both fluoridated and non-

fluoridated sealant are not statistically significant (Koch

1997).

Caries reduction of sealants is mainly due to mechanical

sealing of fissures and blocking nutrients for bacteria

from oral environment.

Glass ionomer sealants

because of its fluoride releasing ability, considered to be

effective in reducing caries. So this cement was tried as

sealant, but conventional GIC has very less wear resistance and

in a comparative study between GIC and resin as sealants the

latter showed better caries reduction than GIC.

Resin modified GIC compomer

are also used as sealants nowadays as they have better

wear resistance than conventional GIC.

Ionosit seal compomer pit and fissure sealant

Contains an ionomer glass in polymerizable polycarbonic

acid.

Opaque appearance, fluoride releasing. Releases zinc ions

after set and thus produce antibacterial effect.

Available with fine long tipped nozzles which allows

precise application (BDJ 2003).