Management of deep carious lesions seminar/ dental implant courses by Indian dental academy

1

MANAGEMENT OF DEEP CARIOUS LESIONS

Seminar By

Dr. S. HIMAGIRI Postgraduate Student

DEPARTMENT OF CONSERVATIVE DENTISTRY & ENDODONTICS SRI RAMACHANDRA DENTAL COLLEGE AND HOSPITAL CHENNAI

2

CONTENTS

•

Introduction

1

•

Clinical and histological characteristics of dental caries

3

•

Types and layers of dentinal carious lesions

6

•

Effect of caries on the pulp-dentin organ

10

•

Diagnosis and prognosis of deep carious lesions

13

•

Instrumentation for removal of deep carious lesions

18

•

Chemo chemical caries removal

19

•

Materials used in pulp production

22

•

Indirect pulp therapy

29

•

Direct Pulp capping

36

•

Caries activity tests

39

•

Conclusion

43

3 INTRODUCTION One of the basic steps in a restorative procedure is the removal of carious dentin. Unfortunately, this procedure is still empirical, resulting in a great deal of inconsistency.

It is well-documented fact that

recurrence of decay under and around restorations is primarily caused by the mishandling of carious tooth structure at the time of tooth restoration (M.A Marzouk).

The term “caries control� treatment refers to an operative procedure in which multiple teeth with acute threatening caries are treated quickly by (1) removing the infected tooth structure (2) medicating the teeth (3) restoring the defects with a temporary restorative material, with this technique, most of the infecting organisms are removed, limiting further spread of caries through out the mouth (Theodore. M. Roberson) Many of the deep carious lesions appear radiographically to be dangerously close to the pulp (or) to actually involve the dental pulp.

Approximately 75% of the teeth with deep caries have been found from clinical observations to have pulpal exposures.

[Diamaggio & Hawes,

1974].

When dealing with a deep cavity, the dentist can probably be assured that he has invaded a reparative dentin. Therefore, the dentist should take every precaution to minimize the trauma of the operative procedure. Otherwise the pulp can lead to irreparable changes.

4 CLINICAL AND HISTOLOGICAL CHARACTERISTICS OF DENTINAL CARIES - “Reparative responses�

Progression of caries in dentin is different from progression in the overlying enamel. There is much more organic material in dentin, and it possesses the microscopic tubule that provide a freeway for the ingress of acids and egress of mineral. The dentino-enamel junction has the least resistance to caries attack and allows rapid lateral spreading once cares has penetrated the enamel.

Because of these characteristics, dental

caries is v- shaped in cross section with a wide base at the dentino-enamel junction, and the apex directed pulpally. response

in

remineralization.

dentin,

including

Caries produces a variety of

pain,

demineralization,

and

The pulp- dentin complex reacts to caries attacks by

tempting to initiate remineralization and blocking off the open tubules.

These reactions results from odontoblastic activity as well as the physical process of demineralization and remineralization.

Cross section of dentinal caries

5 Three levels of dentinal reaction to caries can be recognized 1. Reaction to a long-term, low-level acid demineralization, associated with a slowly advancing lesion.

2. Reaction to a moderate – intensity attack.

3. Reaction to severe, rapidly advancing caries.

In slowly advancing caries, a vital pulp can repair demineralized dentin and by apposition of peri-tubular dentin. Early stages of caries or mild caries attacks produce long-term, low-level acid demineralization of dentin. Dentin responds to the stimulus of its first caries demineralization episode by deposition of crystalline material in both lumen of the tubules and the intertubular dentin of affected dentin in front of the advancing infected dentin portion of the lesion.

Hyper mineralized areas may be

seen on radiographs (often S-shaped following the course of the tubules) ahead of the advancing, infected portion of the lesion. This repair only occurs if the tooth pulp is vital. Dentin that has more mineral content than normal dentin is termed “sclerotic dentin�.

Sclerotic dentin

formation occurs ahead of the demineralization front of a slowly advancing lesion and may be seen under an old restoration.

Sclerotic dentin is

usually shiny and darkly colored but feel hard to the explorer tip.

Apparent function of sclerotic dentin is to wall off a lesion by blocking (sealing) the tubules.

The permeability of sclerotic dentin is greatly

reduced in comparison to normal dentin because of the decrease in the tubule lumen diameter (Pashley 1991).

The second level of dentinal response is to moderate intensity (or) intermediate irritant. invasion of the dentin.

More intense caries activity results in bacterial The infected dentin contains a wide variety of

pathogenic materials or irritants, including high acid levels, hydrolytic

6 enzymes, bacteria and bacterial cellular debris.

These materials can

cause the degeneration and death of the odontoblasts and their tubular extensions below the lesion, as well as a mild inflammation of the pulp.

Groups of these dead, empty tubules are termed “dead tracts�.

The pulp may be irritated sufficiently from high acid levels or bacterial enzyme production to cause the formation of replacement odontoblasts (secondary odontoblasts).

These cells produce reparative

dentin (reactionary dentin) on the affected portion of pulp chamber wall.

The structure of reparative dentin can vary from well - organized tubular dentin to very irregular a tubular dentin, depending on the severity of the stimulus.

Reparative dentin is a very effective barrier to diffusion of

material through the tubules and is an important step in the repair of dentin.

The success of dentinal reparative responses depends on either by remineralization of intertubular dentin and opposition of peri-tubular dentin. Reparative dentin formation depends on the severity of the caries attack and the ability of the pulp to respond. The pulpal blood supply may be the most important limiting factor to the pulpal responses.

The third level of dentinal response is to severe irritation. Acute, rapidly advancing caries with very high levels of acid production overpowers dentinal defenses and results in infection, abscess, and death of the pulp.

In comparison to other oral tissues, the pulp is poorly

tolerant of inflammation. Small, localized infections in the pulp produce an inflammatory response involving capillary contraction, local edema, and stagnation of blood flow.

Since the pulp is contained in a sealed

7 chamber and its blood is supplied through very narrow root canal. Any stagnation of blood flow can result in local anoxia and necrosis. The local necrosis leads to more inflammation, edema, and stagnation of blood flow in the immediately adjacent to pulp tissue, which then becomes necrotic in cascading process that rapidly spreads to involve the entire pulp.

Maintenance of pulp vitality is dependent on the adequacy of pulpal blood supply. Recently erupted teeth with large pulp chambers and short, wide canals, with large apical foramina have more favorable prognosis for surviving pulpal inflammation than fully formed teeth with small pulp chambers and small apical foramina.

TYPES AND LAYERS OF DENTINAL CARIOUS LESIONS There are two types of carious processes 

Acute



Chronic

They differ in the dynamic of their creation, the reaction of tissues to them, and resultant end- products of their activity.

Any dentinal carious lesion in a vital pulp dentin organ will exhibit five layers, (or) zones, when un-decalcified tooth sections are examined under an optical microscope.

These zones are differing in their dimensions, contents, nature, and activities in the two types of carious processes. The five zones are:

8 i. Decayed zone ii. Septic zone iii. Demineralized zone iv. Transparent zone v. Opaque zone Zones of decay in acute decay

Zones of decay in chronic decay

a. Decayed zone, b. Septic zone, c. Demineralized zone, d. Transparent zone, e. Opaque zone.

DECAYED ZONE The dentin in this zone is almost completely devoid of minerals, more so in acute than in chronic lesions. The organic matrix is completely decomposed to an unrecognizable state.

Collagen fibers, if found, have

completely lost their cross striations and links.

There is a high

concentration of microorganisms in the destructed dentin mass with substantial amounts of residual plaque deposits, the only activity in this layer is microbial, its thickness will vary depending upon whether it is an opened, partly opened, or closed lesion. The maximum thickness is found in closed lesions.

The decayed zone is clinically similar in acute and

chronic lesions, with the exception that chronic lesions may be more odiferous, due to extensive lysis, and darker in color, due to the longer duration of the decay process, which allows for greater activity of chromogenic bacteria.

9 SEPTIC ZONE The highest concentration of microorganisms is found here.

Although the dentin is very well decalcified, its framework structure can still be recognized, but the collagen fibers have fewer cross band striations than normal, and intermolecular links are lost. The dentinal tubules are extremely wide-ended and cavitated. This layer may have slightly greater dimensions in chronic than in acute decay. activity is found in this layer.

And again only microbial

The colour resembles that of the decayed

zone (Ranging from light yellow to a dark reddish brown, depending upon the presence and duration of chromomeric bacterial activity).

The decayed and septic zones have the softest consistency of all the zones, and the consistency is softer in an acute lesion than in chronic lesion.

DEMINERALIZED ZONE Clinically this is the most significant zone both diagnostically and therapeutically. Here the dentin is only demineralized with the dentinal matrix still intact.

The dentinal tubules still have their normal

dimensions, although there are destructive activities in the form of decalcification, there are also repair activities in different forms of remineralization, precipitating a variety of phosphate crystals in different shapes and compositions ex. Tri calcium phosphate, (white lockite), regular apatite crystals, specially acute and chronic decay differ greatly in this zone.

10 The dimension of this zone is greater in an acute lesion than in a chronic lesion. According to Fusayama a maximum width of this layer is 1750µm in acute decay, whereas minimum of 50µ width in chronic decay.

Remineralization activities are much less pronounced in acute decay, with a

lower

percentage

of

deposition

of

new

phosphate

crystals.

Microorganisms will be confined to the superficial 1/3 - ½ of this zone in acute decay, but will be found throughout this zone in chronic decay. The color of this zone in acute decay is straw yellow, for chronic decay the color is always yellow brown (or) dark-brown.(Fusayama & Ohguushi) Consistency and hardness of the dentin in acute decay is much less (possibly more then 15 times less than in chronic decay).

TRANSPARENT ZONE This zone appears transparent in ground sections, but will definitely appear radio opaque in a radiograph.

It is the area of undisturbed

mineralization repair and zone of dentinal sclerosis and the calcific barrier. This zone is more pronounced in chronic decay.

This zone may contain a few microorganisms in a chronic lesion.

Clinically, this zone may be slightly discolored compared to the surrounding un-attacked dentin due to the remineralization of decalcified stained dentin.

OPAQUE ZONE This zone is usually found pulpally to the transparent zone. It is characterized by intertubular fatty degeneration with lipid deposits being

11 precipitated from fatty degeneration of the peripheral odontoblastic process.

This type of degeneration predisposes to the sclerosis of the

dentinal tubules. This zone is more pronounced in acute lesions and will appear radiolucent in radiographs (Miller 1969).

The process of decay advances until each of these zones, starting with the opaque zone, arrives at the pulp. The maximum resistance to pulpal penetration occurs with the arrival of the transparent and demineralized zone.

However, if the septic zone penetrates the pulp

chamber the pulp dentin organ will be unable to offer any resistance, and will suffer complete collapse.

One should bear in mind that the chronic or acute status of a lesion can be changed if there is a change in the environments encouraging one condition over the other.

EFFECT OF CARIES ON THE PULP-DENTIN ORGAN The carious process creates three distinct forms of irritants •

Biological irritants (microorganisms and their metabolites.)

•

Chemical irritants (acids)

•

Physico-mechanical irritants [the gradual diminution of the effective depth of the pulpal dentin organ due to the advancing carious process] Each of these irritants will precipitate a reaction in the pulp dentin

organ at one stage of its progress.

It has been demonstrated by some

investigators that the pulp dentin organ will react to caries as early as the stage of enamel caries.

Conversely, other investigators proved that no

12 actual reaction will from until the caries is 2 mm or less from the pulp chamber. These diverse results Merely confirm that the many factors are involved in the type, extent, and destructive protective nature of the pulp dentin organ reaction toward the caries irritation. Therefore, for proper therapy, it is essential to correctly diagnose the type, extent and nature of the pulp-dentin reactions to the decay process. The following factors are guidelines for this essential information.

TYPE OF DECAY Understandingly, the more acute the decay process is, the less effective the defensive reparative mechanism will be, with a greater tendency towards a destructive reaction in the pulp dentin organ.

Chronic decay is usually accompanied by substantial repair provided it has not involved the pulp (or) root canal system.

DURATION OF THE DECAY PROCESS The longer the duration in acute decay, the more massive the destruction of tooth structure. The longer the duration in chronic decay, the greater the chances for repair, provided the pulp chamber, root canal system are not directly involved.

The carious process in chronic decay can stimulate repair. In acute lesions however, due to high diffusion of microbial irritants, the carious process can be very destructive.

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DEPTH OF INVOLVEMENT It is simple mechanics and physics that the deeper the caries is, the nearer the source of irritation to the pulp. This creates greater intensity of irritation with a greater possibility of pulpal destruction.

For peripheral involvements, we would anticipate either no pulpal reaction at all, or a reparative reaction in both acute and chronic lesions.

For moderate depth involvement, we can expect the same reaction from chronic decay as was observed in peripheral involvement, for acute lesion of moderate depth we would observe some resolved pulpal destruction.

For profound depth involvement, we can expect some repair and perhaps resolved pulpal destruction in acute decay.

For perforating lesions, we can expect pulpal destruction in both types of decay.

NUMBER AND PATHOGENECITY OF MICROORGANISMS The greater the virulence and population of microorganisms are, the greater

is the

likelihood

destruction.

TOOTH RESISTANCE

of the

pulpal reaction

ultimately being

14 This involves an infinite number of factors, ranging from the thickness of dentin through which the decay must pass to initiate a recognizable effect, the permeability of the involved dentin, the solubility of the involved dentin, the fluoride and calcium content of the involved dentin and the susceptibility of the tooth etc.

EFFECTIVE DEPTH (M.A. Marzouk) Definition: the effective depth is the area of minimum thickness of sound dentin separating the pulpal tissues from the carious lesion. This is usually found in the deepest portion of the caries activity 1) When we have an effective depth in the pulp dentin organism of 2mm (or) more. We can expect a healthy reparative reaction.

2) When the effective depth is from 0.8 – 2 mm, we can expect an unhealthy reparative reaction.

3) When the effective depth is less than a 0.3 – 0.8 mm range, we can expect pulpal destruction.

Effective depth = Effective depth in radiograph x Actual Enamel thickness ---------------------------------------------------------------------------Enamel thickness in radiograph DIAGNOSIS AND PROGNOSIS OF DEEP CARIOUS LESIONS Unfortunately, our available diagnostic tools are not sufficiently reliable to get an exact picture of the involved tissues and tooth, however, by combining the results of the following clinical tests and observations.

We can gain a good diagnostic perspective.

15

PAIN The absence of pain cannot be used as deciding criteria for the status of pulp dentin organ although the teeth with non-vital pulp dentin organ are frequently painless.

The presence of pain may serve as guiding criteria for the status of the pulp dentin organ, although this is not very reliable. For e.g. when pain at night or spontaneous pain not initiated by thermal or chemical stimulation of the pulp dentin organ could indicate possible destructive degenerative changes in the pulp dentin organ. However, pain initiated by thermal or chemical stimulation of the pulp dentin organ that disappears immediately after the removal of the stimulation is a possible indication of a much less degree of degenerative changes.

Any symptoms of pain

should be recorded in the patient’s own words RADIOGRAPHS Radiographs give a two-dimensional image of three-dimensional structures. Radiographs, especially periapical radiographs. Can be a very practical supporting tool. A radiographs can indicate: a)

The thickness of the dentinal bridge (effective depth) can be estimated. It should be emphasized that the extent of the carious lesion as shown in the radiographs will always be less than the actual size of the lesion.

16 b)

The thickening of the periodontal ligaments space with an intact laminadura,

especially

periapically

will

indicate

increased

vascularity and consequently increased activities of the pulp dentin organ, discontinuity in the laminadura may indicate more advanced activities of the pulp dentin organ, possibly destructive in nature. c)

The location of the caries cone tip relative to the anatomy of the pulp chamber and root canal system.

Caries cones proximate to

constrictions in the pulpal or root canal tissues will profoundly affect the design of the cavity preparation and the choice of an intermediary base.

The gross evaluation of mineralization, and consequently the permeability, of the involved dentin, We can radiographically identify sclerotic dentin, which will appear radio-opaque, and tertiary dentin, which will appear as a localized thickening of the dentinal bridge, pulpal to the lesion, creating irregularities in pulp chamber or root canal walls and/or roof.

This data is very important in determining the reparative

capability of the pulp dentin organ and the type of intermediary base to be used THERMAL TESTING Heat→ Gutta percha sticks Cold→ ice, cotton pellet soaked in ethylchloride, liquid nitrogen ELECTRIC PULP TESTING If the required energy is higher in the control teeth, this is an indication of possible acute changes in the pulp dentin organ of the affected tooth.

If required energy is lower in control teeth, this may

17 indicate possible progressive changes, advance repair, (or) walling off of the pulp dentin organ from the offending lesion.

DIRECT PULP EXPOSURE The direct pulp exposure usually accompanied by symptoms, which are the most indicative of the actual condition of the pulp dentin organ.

The following is the data that can be collected from observation of a direct pulp exposure and its clinical significance: A)

A pinpoint exposure having sound dentin at a periphery of the exposure, with no hemorrhage, in a vital pulp dentin organ, is an indication of either no pulpal inflammation or a mild degree of pulpal inflammation restricted to the exposure site.

This can be

successfully repaired, if properly treated.

B)

A pinpoint exposure having sound dentin at its periphery, but accompanied by a drop of blood that coagulates immediately on the cavity floor in the form of a button is also an indication of healthy reparable pulp dentin organ.

C)

An exposure having decayed or infected carious dentin at its periphery would indicate considerable inflammation in pulp tissue.

The reparability of this type of exposure is doubtful.

D)

An exposure accompanied by profuse hemorrhage could be an indication of great involvement (usually mechanical) of the pulpal tissue. This type of exposure is usually beyond repair.

PERCUSSION SENSITIVITY

18 Tenderness to percussion is of little value in determining the degree of inflammation in the pulpal and root canal tissues. It determines the pathology in periapex, therefore percussion Merely demonstrates the likelihood of some type of pathology in the pulp dentin organ.

TYPE OF DENTIN Visual examination and tactile evaluation by use of an explorer can give us an idea of the type of dentin present in the preparation walls and floors.

The presence of calcific barrier or sclerotic dentin closer to the

pulp indicates reparative activity. Generalized discoloration of the dentin, not arising from a previous amalgam restoration, and which ranges from grayish pink to grayish brown, may indicate a devitalized or dying p-d organ that has lost all reparative capacity.

Use of dyes to differentiate between reparable and irreparable dentin: •

Suggested method to guide an operator as to where to stop in excavating dentin from cavity walls and floors is to apply a solution of 0.5% basic fuchsin in propylene glycol to the dentin for 10 seconds, then thoroughly wash the preparation with water.

The irreparable

areas of dentin will distinctly stain red. Fusayama and his coworkers have shown that the banding between reparable and irreparable areas will be very clear to the unaided dye. They claim that the nature of the collagen fiber constitutes the difference in the stainability in the two layers of dentin.

The reparable attacked dentin will have intact

collagen fibers oriented for remineralization and will not stain with the fuchsin solution. However, the irreparably attacked dentin will have its

19 collagen fibers denatured to the extent of being non-receptive to remineralization and can be stained red by the fuchsin solution.

Another dye, which creates the same effect, is a 1% acid red solution in propylene glycol.

INSTRUMENTATION FOR REMOVAL OF DEEP CARIOUS LESIONS The removal of the harder, heavily discolored dentin, can be achieved by either methods 1)

Use of spoon excavators

2)

Round stainless steel burs at very low speed

3)

Round carbide burs rotating at high speed.

Spoon excavators are designed specially for the removal of carious dentin. They are frequently used in conjunction with rotary instruments.

The extent of the lesion should determine the size of the spoon excavator to be used.

Sharp excavators are effective and will reduce the force

required for carious removal. A carious mass can often be “peeled� out in sizable portions. Large increments should be removed only early in the process. The forces of removal are directed laterally, that is paralleling the outline of the pulp chamber.

Rotating instruments used at slow speed are well suited to the removal of carious dentin. Steel burs are more advantageous then carbide burs because A) Steel bur has a greater number of flutes than does the carbide bur B) A smoother cutting action is achieved using this bur

20 Discrimination between carious and normal dentin must be made by operator, a light force is applied to the bur. A wiping motion being used.

CONSIDERATIONS IN THE REMOVAL OF DEEP CARIOUS LESION Primary concern is for the pulp, pulpal damage may result from the creation of frictional heat with the use of bur. Forcing microorganisms into the dentinal tubules through excessive pressure with a bur or spoon excavator may infect the pulp.

The pulp may expose when either

instrument is used [bur, excavator]. Thus ideal method of removing this material would be one in which minimal pressure is exerted, frictional heat is minimized, and complete control of the instrument is available.

Considerations of above factors usually favors the use of a round carbide bur, in a high-speed hand piece, with air coolant and slow speed.

Examination of the area with an explorer following the removal of infected dentin is advisable, but should be done judiciously to avoid perforation in to the pulp.

REMOVAL OF REMAINING OLD RESTORATIVE MATERIAL Is accomplished with use of a round carbide bur, at slow speed with water coolant.

Along with high – volume evacuation is used when

removing old amalgam material to reduce the amount of mercury vapor.

21 CHAMICO MECHANICAL CARIES REMOVAL Dentin consists of mineral (70 wt %), water (10 wt %) and an organic matrix (20 wt %) of this organic matrix 18% collagen and 2% condition sulphate, proteogelycans phospholipids.

Collagen is an unusual protein, which contains large amounts of proline and one third of amino acid content, is glycine.

CARISOLV Composition (GEL) Solution I

-

0.5% Sodium hypo chloride

Solution II

-

0.1 M Glutamic acid / Leucine / Licine Sodium chloride / Sodium hydroxide Erythrocin

CARIDEX COMPOSITION (SOLUTION) Solution I

-

1% Sodium hypo chloride

Solution II

-

0.1 M Amino butyric acid / Glycin 0.1 M Sodium hydroxide 0.1 M Sodium chloride

When solution I and II mixed, there will be a chlorination reaction and forms “N-Monochlorobutyric acid�, this N-Monochlorobutyric acid removes glycine from the polypeptide chains of collagen by oxidation

22 reaction.

This causes disruption of the collagen fibrils, which become

more friable and can be removed easily (Yip and Goldman 1989).

TREATMENT OF ACUTE DECAY Acute decay can be treated in the following sequence; all possible information regarding the status of the pulp dentin organ should be collected. All undermined or unwanted enamel in the preparation should be removed. If it is safe to remove all softened dentin without creating an exposure, this should be done using a spoon excavator. The reparability of the remaining dentin should be verified using basic fuchsin or acid red dye solutions. Any, non-reparable dentin should be removed.

If there is imminent danger of creating a pulp exposure by removing all softened dentin, the deepest layer should be left, provided; 1)

The pulp dentin organ has been established as being healthy.

2)

The

remaining

dentin

has

been

established

as

being

reparable.

3)

The softened dentin that is to remain should be located in the deepest part of the pulpal and or axial wall. The surrounding walls and at least a portion of the pulpal and axial walls should be in hard sound dentin.

If there is any doubt about above 1 and 2 factors treat the lesion by pulp capping procedure (or) root canal treatment.

TREATMENT OF CHRONIC DECAY

23 Should

be

treated in

the

following sequence. Evaluate the

physiologic status of the pulp dentin organ, all undermined or unwanted enamel in the preparation should be removed, all softened dentin should be removed using either spoon excavator or large sound stainless steel bur in a slow speed hand piece. If removal of softened dentin leads to an exposure of the pulpal or root canal tissues, proceed either with the appropriate pulp capping procedure or with endodontic therapy.

MATERIALS USED IN PULP PROTECTION Cavity Varnishes The typical cavity varnish is principally a natural gum (such as copalrosin, (or) a synthetic resin dissolved in an organic solvent such as acetone, chloroform, and ether. Varnish produces a positive effect on the reduction of pulpal irritation.

This suggests that the effect may be

attributed to the reduced infiltration of irritating fluids through marginal areas.

Varnish also prevents penetration of corrosion products of amalgam into the dentinal tubules, and it thereby reduces the unsightly tooth discoloration often associated with amalgam restorations.

Conventional cavity varnishes should not be employed under composite restoration, because the solvent in the varnish may soften the resin and the coating prevents proper wetting of the prepared cavity by the bonding agents. However, if sufficient time is allowed for evaporation of

24 the organic solvent, such degradation of subsequent composite may not occur (Anusavice).

CAVITY LINERS AND BASES The main difference between a liner and a base is the thickness and strength.

The term liner is used for “thin wash” a base is a relatively

thick material strong enough to provide resistance form and to become a intrinsic part of the ultimate restoration.

A base can be regarded as a

dentin substitute.

CAVITY LINERS Traditionally, it is formulated by dispersing calcium hydroxide in aqueous or resin carrier solutions to facilitate application to the walls of a cavity preparation.

The carrier evaporates and leaves a thin layer of

calcium hydroxide on the cavity walls.

Instead of using suspension formulation, several other hard – setting materials are available.

They include calcium hydroxide, low

viscosity zincoxide eugenol (type – iv), and glass ionomer liner.

These

materials are placed in a thin layer on the pulpal floor.

CEMENT BASES The function of bases, which are thicker protective layers of cement that are placed under restorations, is to encourage recovery of the numerous types of insult to which it may be subjected.

These insults

include, thermal shock, and chemical irritation, etc, the base essentially

25 serves as replacement or substitute for the protective dentin that has been destroyed by caries, cavity preparation, or both.

There are a variety of materials that have been used as bases. Such as, zinc phosphate, poly-carboxylate, glass ionomer, etc.

THERMAL PROPERTIES Thermal conductivity values of zinc phosphate zincoxide eugenol cement are similar to those of recognized insulators, such as cork, and asbestos.

THERMAL CONDUCTIVITY OF VARIOUS CEMENT BASE MATERIALS Materials

Thermal Conductivity [(c°/ cm-1) ] x 10-4

Zinc phosphate

3.11

Zinc oxide eugenol

3.98

Asbestos

1.90

Cork

7.00 Clinical experience has shown that temperature changes in the

mouth have a more acute effect on the pulp when a base does not insulate the amalgam restoration (Anusavice).

Heat transfer through a material is dependent not only n the coefficient of thermal conductivity and diffusibility of the substance but also on its thickness. calcium

hydroxide

Studies shown that thermal insulation ability of

base

and

zincoxide

eugenol

cement

decreases

substantially when the thickness of the base is reduced to 0.15 mm. The

26 minimal thickness required for adequate thermal insulation is estimated to be 0.75 mm (Anusavice).

PERFECTION AGAINST CHEMICAL INSULT Cements provide effective barriers against the penetration of irritating constituents from restorative materials.

Bases such as hard setting calcium hydroxide zincoxide eugenol, carboxylate cements, glass ionomer cements can be used as chemical barrier.

CLINICAL CONSIDERATIONS The selection of a base is governed by the design of the cavity preparation, the type of direct restorative material used, and the proximity of the pulp in relation to the cavity wall. With amalgam, restorations one of the hard – setting calcium hydroxide material or zincoxide eugenol usually serve effectively as the sole base. In other situations, such as with direct – filling gold, it may be necessary to use a stronger material for the base, such as zinc phosphate, poly-carboxylate or glass ionomer.

With

resin restorations in deep caries calcium hydroxide is the material of choice as a thin base over the composite restoration. Where as zincoxide eugenol is contraindicated because it interfere with polymerization of composite material (AUJ Yap et al).

In summary, cavity varnishes and cement bases generally serve somewhat different functions. In deep cavity, where maximum protection against all types of insult is required, both a varnish, and a base may be needed.

27

ZINC PHOSPHATE CEMENT Zinc phosphate has limited value us a lining cement.

This cement

has been used for many decades as an insulating base material beneath metallic restorations and also as a luting agent. Despite its acid nature, it is well tolerated by the pulp if placed on intact dentin, presumably because of buffering of the unreacted acid by hydroxyapatite. There may be immediate and short-term pain if it is placed on the dentin of an unanesthetized tooth.

Thus seems to be few indications for its use as a

lining or base material. When using zinc phosphate cements as a base, the consistency should be very thick like putty.

Cavity varnish applied prior to cements base serves as an adherent to hold the cement securely against the dentin and also as a barrier against irritation from the unset cement.

Effect of zinc phosphate cement at different effective depth 1)

At an effective depth of 2.5 mm and more, zinc phosphate cement will usually create a healthy reparative reaction.

2)

At effective depth 1.3 to 2.5mm, we can anticipate an unhealthy reparative reaction.

3)

At effective depth less than 1.5mm, there will always be destruction in pulpal tissues.

Ph of zinc phosphate cement is 3 – 4 in the first hour, within 48

hours it becomes neutralize.

28 ZINCOXIDE EUGENOL PROPERTIES Anti – inflammatory Anti – bacterial Mildly anesthetic Good seal to cavity wall Therefore, if should be used as a short – term temporary indirect pulp cap, zincoxide eugenol is a useful part of pulp therapy in the management of deep, active carious lesions and has also been used as a lining and base material.

It provides an effective anti bacterial seal

probably because any gap between the cement and dentin will contain a high concentration of eugenol, which is strongly bactericidal (Jung et al).

Any available eugenol may also inhibit bacterial metabolism within dentin, and if the material is placed on intact dentin it is unlikely to harm pulp cells.

It is also possible for it to promote local anesthetic and anti –

inflammatory reactions in adjacent pulp tissue.

Indications for the use of zincoxide eugenol are limited to those situations where the dentin is intact and some form of indirect pulp therapy or caries therapy is required.

EFFECTIVE DEPTH Zincoxide eugenol can have irritating actions on the pulp dentin organ up to an effective depth of 1 mm.

POLY CARBOXYLATE CEMENT

29 pH of the setting cement is in the range of 1.5 for the first day. It is less irritating to pulp dentin organ compared to zinc phosphate cement.

Because of giant dimensions of poly acrylic acid macromolecules and their attachment to the main bulk of the cement mass.

The acid has low

diffusion mobility into the underlying dentin due to its immediate complexing with dentinal fluoride, calcium, and some proteinacious components; the complexed product will prevent further penetration of the acid.

EFFECT

OF

POLY

CARBOXYLATE

AT

DIFFERENT

EFFECTIVE

DEPTHS: •

Whenever pulp dentin organ has a 1mm, effective depth or greater, a healthy reparative reaction can be expected.

•

Whenever effective depth is less than 1 mm, we can expect either unhealthy reparative reaction, or more frequently, destruction.

•

Whenever the material comes in contact with the pulp or root canal tissue, destruction reaction will definitely be initiated.

GLASS IONOMER CEMENT PROPERTIES Excellent Dentin Substitute Because •

Ion-exchange layer seals dentinal tubule

•

It is mildly antibacterial

• It has adequate physical properties

30 When glass ionomer is placed on intact dentin, posses no chemical risk to the pulp and, with the development of the ion- exchange layer, it creates an effective antibacterial seal. It shows a very low solubility, and therefore appears to be the material of choice for use as a base, or dentin substitute.

Glass ionomer used as a long-term temporary restoration in the treatment of active caries. Following removal of infected dentin, a strong mix of glass ionomer placed in the cavity over the remaining affected dentin and allowed to set, in the presence of dentinal fluid from the affected dentin there is likely to be a reasonable release of fluoride as well as calcium and phosphate ions from the cement and these will be useful in remaining tooth structure through ion – exchange mechanism and, in addition, it is apparently mildly antibacterial because of fluoride release.

INDIRECT PULP THERAPY DEFINITION When caries is close to the pulp, excavation of caries can be stopped at stained but firm dentin calcium hydroxide lining is applied over the pulpal dentin prior to placement of the definitive restoration this is classically referred to as the indirect pulp cap.

INFECTED LAYER The superficial surface of carious lesion, adjacent to the oral cavity is heavily infected by microorganisms and consists largely of denatured and unstructured enamel and dentine debris.

31 AFFECTED LAYER Beneath the infected layer a zone of demineralized dentin that retains the basic structure but relatively free of bacteria except possibly for a few pioneer bacteria.

Under magnification, the original dentinal

tubules are apparent, supported mainly by the collagen matrix and this may, under normal circumstances, be demineralized (McDonald).

The removal of the superficial infected dentin is a major component of the surgical treatment of an advancing carious lesion, and this is relatively simple to accomplish. The affected zone is not always easy to define because it is relatively soft, generally colorless and its complete disclosing solutions are reasonably reliable in as much as they will define the infected layer and leave the affected dentin unstained. However caries control in an extensive lesion should be carried out in two stages.

1)

Perform limited debridement to remove the infected dentin only and to clean the walls around the periphery of the lesion. Now place a temporary restoration, using a material, which is capable of providing a complete marginal seal leave in place for at least 3 weeks.

2)

Remove the temporary and complete the debridement before finalizing cavity design and placing a definitive restoration The first stage allows time for the inflammation to subside and for

the pulp to lay down reparative dentin in those areas close to exposure, if the pulp survives the inflammation and retains its vitality; there will be a degree of remineralstion in the affected demineralized zone.

Secondary

dentin formation will follow with in the pulp chamber because the tissue fluid in the pulp is naturally supersaturated with calcium and phosphate ions.

32 TEMPORARY RESTORATION Main function of temporary restoration is to provide a complete seal so that any remaining bacteria will be deprived of nutrition and will not able to produce sufficient acid for demineralization to continue. Another INDIRECT PULP CAPPING TECHNIQUE advantages are antiseptic or antibacterial effect on the remaining microorganisms. It helps stimulate remineralization.

a

c

e

b

d

f

a. Isolate the tooth with a rubber dam, b. Extend the preparation with a No.33o bur, c. Remove the carious dentin with a slow speed bur, d.

The three layer of carious dentin (A) necrotic tissue, (B) Leathery, and (C) The 1mm to remain, e. Place calcium hydroxide over the carious dentin, f. Placed ZOE material over the calcium hydroxide.

33

CLINICAL PROCEDURE FOR INDIRECT PULP THE RAPY Damle in 1961 stated that the purpose of indirect pulp capping was the use of “reconstructed” dentin to prevent pulp exposure.

INDICATIONS HISTORY •

Tolerable dull mild discomfort associated with eating

•

Negative history of spontaneous extreme pain

CLINICAL EXAMINATION •

Large carious lesion

•

Normal mobility

•

Normal appearance of adjacent gingiva

•

Normal color of tooth

34

RADIOGRAPHIC EXAMINATION •

Large carious lesion with close proximity to the pulp

•

Normal laminadura

•

Normal periodontal ligament space

•

No radiolucency in the bone (apical region)

CONTRA INDICATION HISTORY •

Sharp penetrating pulpalgia, indicating acute pulpal inflammation.

•

Prolonged night pain.

CLINICAL EXAMINATION •

Mobility of the tooth

•

Negative response to electric pulp test

RADIOGRAPHIC EXAMINATION •

Large carious lesion producing definite pulp exposure

•

Interrupted or broken laminadura

•

Widended periodontal ligament space

•

Periapical radiolucency

PROCEDURE (Eidelman 1965) FIRST VISIT •

Local anesthesia and isolation (if necessary)

•

Cavity outline using high-speed hand piece

35 •

Removal of superficial debris and most of soft necrotic dentin with slow speed hand piece using large round bur or excavator.

Care

taken to eliminate all caries at dentino-enamel junction, care taken not to expose pulp.

•

Flush saline and dried with cotton pellet.

•

Placement of calcium hydroxide or zincoxide eugenol in the base of cavity.

•

Reinforced zincoxide eugenol filled in remainder cavity.

•

Do not disturb this sealed cavity for six to eight weeks.

NOTE: Keep in mind as you progress to wards pulp A)

Outer most layer of dentin will be necrotic (Mushy) tissue.

B)

Next will be leathery but firmer

C)

Last 1mm, is left in cavity

SECOND VISIT

36 •

The radiographic evidence of sclerotic dentin formation is evident after 10 to 12 weeks only, though re-hardening occurs in 6 to 8 weeks. The rate of reparative dentin formation decreases markedly after 48 days (Stanley H.R 1966) Reparative dentin formation is 1.4 µm/day.

•

Isolation of the tooth

•

Tooth re-entered and calcium hydroxide and remaining caries removed. The color of caries will have changed from deep red rose to light gray or brown. The texture changes from spongy and wet to hard, the area around the potential exposure will appear whitish and soft, this is the pre dentin, which should not be disturbed.

•

The entire floor is covered with calcium hydroxide, base is built with reinforced zincoxide eugenol (or) glass ionomer cement and then final restoration is placed.

Controversy exists concerning the basing material.

One group

supports that calcium hydroxide must be in contact with pulpal tissue to form reparative dentin.

Another group says that calcium hydroxide is

soluble and hence is transmitted by the fluid in the dentinal tubules to the pulp and form reparative dentin.

The difficulties with the indirect pulp cap technique is •

Knowing how rapid the carious process haw been?

•

How much tertiary dentin is formed?

•

Knowing exactly when to stop excavating to avoid pulp exposure?

Using a step wise approach to caries removal above parameters can be regulated with a predictable outcome.

STEP WISE EXCAVATION

37 Introduced by Bjorndal et al (1997). In this technique caries removal was staged over two separate appointments 6-12 months apart.

At the first appointment, access to the caries was gained and the periphery of the cavity made completely caries free. Soft, wet and pale colored dentin was left pulpally, which has previously been shown to be heavily infected.

The cavity was lined with calcium hydroxide and

restored with glass ionomer and left for 6-12 months.

After this period, cavities were re-entered and the dentine in all teeth was found to be darker in color, harder and drier in consistency.

These findings would imply that by removing some of the carious biomass and sealing the remaining caries from extrinsic substrate and oral bacteria, the caries left behind after the first excavation had become less active this allows time for pulp-dentin complex reactions to take place so that at the second excavation visit, there is less likelihood of pulpal exposure.

It has also been suggested that by changing the cavity

environment from an active lesion in to the condition of more slowly progressing lesion, this will be accompanied by more regular tubular tertiary dentin formation.

WHY RE-ENTER? 1)

The success of pulp cap technique is dependent upon the integrity of the restoration and its seal, so the regular recall would identify any lost restoration at an early stage.

2)

Following sealing caries in to the tooth the carious dentin becomes dry, harder and darker in color, as a result there is shrinkage of the tissue leaving avoid beneath the restoration.

38 THE DIRECT PULP CAP A direct pulp cap usually involves the placement of a calcium hydroxide preparation directly in contact with an exposed pulp.

For a direct pulp cap to be successful a number of factors have to be met. These are as follows.

HISTORY •

No recurring or spontaneous pain

•

No swelling

PREOPERATIVE ASSESSMENT •

Normal vitality tests

•

No tender to percussion.

•

No radiographic evidence of periradicular pathology.

•

Young patients.

•

Radiographically obvious pulp chamber and root canal.

CLINICAL FINDINGS •

Pink pulp

•

Bleed if touched but not excessively.

39 PROCEDURE Local anesthesia and isolation.

Importance of rubber dam isolation as it prevents pulp contamination by saliva Preparation of the cavity Cavity is prepared before removing deep caries so that tooth can be quickly restored after pulp treatment thus reducing the risk of contamination Excavate deep carious avoid infected dentin chips being pushed in to exposed pulp Wash the exposure site gently with non-irritating solution (Sterile water or Local anesthesia) and is kept most Apply the basing material over the exposure site

Permanent restoration

40 TWO METHODS EMPLOYED FOR DIRECT PULP CAP TECHNIQUE (Lawrence W. Stockton)

PULP EXPOSURE

Calcium hydroxide Technique

Total Etched Technique

Hemostasis

Hemostasis

Disinfect cavity (Cavity Cleanser)

Disinfect cavity (Cavity Cleanser)

Calcium hydroxide

Calcium hydroxide

Resin modified glass ionomer

Etching Primer

Intermediate restorative material

Dentin bonding system

Restoration

Adhesive Resin modified glass ionomer Restoration

41 CARIES ACTIVITY TESTS Caries activity test also called as caries susceptibility test main aim of use is as motivational tooth for patient education and to develop habits such as regular brushing, mouth rinsing etc.

1) SNYDER’S TEST Basis of this test is that the amount of acid produced is proportionate to the number of acid producing lactobacilli present.

PROCEDURE 1ml of stimulated saliva of the patient is added to glucose agar containing bromocresol green and incubated for 72 hours at 37°C. The color change is examined after 24 hours till 72 hours.

The sooner the

color changes from green to yellow the greater is the caries activity, if color dose not change in 72 hours then the patient is limited caries susceptible.

2) LACTOBACILLUS COUNT TESTS •

If the count is 1000 for ml → caries immune

•

Count for ml <10,000 → high caries susceptible

3) ALBAN TEST (MODIFIED SNYDER’S TEST) PROCEDURE 5 ml of semisolid agar tube is taken, and asks the patient to expoctarte un-stimulated salvia in agar tube, tube is incubated for 4 days and daily observed for the color change. The change of color is scored from 0 to 4. Score is based on the amount of color change from top to bottom in the tube from green to yellow.

42 INTERPRETATION â&#x20AC;˘

If full length is yellow caries susceptibility is high

â&#x20AC;˘

If full length is green patient is immune to caries

Media used for Snyder and Alban test contains Bactopeptone

20grams

Dextrose

20grams

Sodium chloride

5grams

Agar

16gr

Bromocresol green

0.02grams

43 JOURNAL REFERENCES J. A Beeley et al “Chemochemical caries removal: a review of the techniques and latest developments” British Dental Journal 188 (8) 2000.

Reviewed about chemo mechanical caries removal technique and latest developments.

Chemo mechanical caries removal involves the chemical

softening of carious dentin followed by its removal by gentle excavation.

The reagent involved is generated by mixing amino acids with sodium hypo chloride, N-monochloroamino acids are formed which selectively degrade demineralized collagen in carious dentin. The procedures require 5 to 15 minutes.

This system was originally marketed in the USA in

1980’s as Caridex, but disadvantage is large volume (100 to 500 ml) of solution and a special applicator system was required.

A new system

introduced in the market as Carisolv. This comes as a gel requires volume of 0.2 to 1 ml and accompanied by specially designed instrument.

C.A. De Souza et al “ Response of human pulps capped with a selfetching adhesive system” Dental Materials 17, 2001, 230-240.

Evaluated

the human pulp response following direct pulp capping with a Clearfil Liner Bond – 2 and calcium hydroxide. 38 human premolars had their pulp tissue mechanically exposed.

The pulps were cap with test

materials, and cavities filed with Z-100 composite. After 5, 30 and 120 to 300 days the teeth were extracted processed for microscopic examination and they found at short-term, Clearfil Liner Bond-2 elicted a mild to moderate inflammatory pulp response adjacent to exposure site, with time macrophages, giant cells, globules of resin particulates were observed with in the pulp space.

However, calcium hydroxide exhibited an initial

organization of pulp cells underneath coagulation necrosis and dentin bridge formation was observed at long-term evaluation.

44

Lina Maria et al “Pulpal response to different pulp capping methods after pulp exposure by air abrasion” J Clin Pediatr Dent 26(3): 269274,2002. Assessed the pulpal response after pulpal exposure by air abrasion and to evaluate the healing potential after using calcium hydroxide medicament or liner bond II 216 teeth from mixed bred dogs were divided into 4 groups, in group I and II pulp exposure done by air abrasion method and liner bond II, calcium hydroxide used as a pulp capping agents respectively, group III and IV pulpal exposure done by high speed and liner bond II, calcium hydroxide used as a pulp capping agents respectively. The animals were scarified after 7 14 30, and 60 days for histopathological evaluation. And they found 1) pulpal response was not statistically different after pulpal exposure by air-abrasion or high speed the main difference in pulpal healing was dentin bridge formation which was statistically delayed for air abrasion groups, however when liner bond II was used as a capping agent, the formation of dentinal bridge was significantly delayed.

Mustafa Demirci et al “Pulp reaction to a tri-cure resin-modified glass ionomer” Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998; 85:712-19. Evaluated the pulp response to a tri-cure resin-modified glass ionomer compared with zinc oxide-eugenol and silicate cement. premolars in orthodontic patients selected.

60

Class V cavity prepared,

restored with test materials. After 5, 30 and 90 days teeth were extracted for histological evaluation they found tri-cure resin-modified glass ionomer elicited a slightly greater adverse pulp response than zinc oxide-eugenol and silicate cement.

45 CONCLUSION In view of the direct relationship between caries depth and pulpal pathosis, early excavation of what might appear to be superficial caries in the dentin is advocated as sound preventive treatment to minimize pulpal exposure.

If pulpal exposure discovered at the time of the early caries

excavation could be routinely treated with consistently good results, a major problem in dentistry would be solved; thus care must be taken to prevent pulp exposure during the removal of deep caries.