PRESENTATION BY:SAGAR HIWALEMDS 1ST YEAR

DEPARTMENT OF CONSERVATIVE AND ENDODONTICSJAIPUR DENTAL COLLEGE AND HOSPITAL

PRESENTED ON :4oct 2013

STRUCTURE OF ENAMEL- CLINICAL IMPORTANCE CLINICAL CONSIDERATIONS ENAMEL DEFECTS Carious defects 1. Incipient caries2. Arrested caries Non carious defects1. Developmental defects: 2. Systemic conditions affecting enamel3. Regressive defects: Discolorations Age changes and clinical consideration CLINICAL IMPLICATIONS Fluoridation Acid etching Enamel microabrasion Enamel macroabrasion CONCLUSION REFRENCES

MINERAL CONTENT Enamel is the hardest tissue in the

human body. Its mineral portion is approximately 96% of its weight,the rest is organic components and water.

The mineral elements include hydroxyapatite

crystals, approximately 0.03μm to 0.2 μm, surrounded by a thin film of firmly bound water.

CLINICAL SIGNIFICANCE:- Poorly mineralized enamel –more white More mineralized –more translucent.

DIRECTION OF RODS• The rods are oriented at right angles to the dentin

surface.• In the cervical & central parts of the crown of a

permanent teeth, they are approximately horizontal.

• Near the incisal edge or tip of cusps they change gradually to an increasingly oblique direction until they are almost vertical in the region of the edge or tip of the cusps.

• CLINICAL SIGNIFICANCE:-• Follow the direction of enamel RODS during

cavity preparation so that enamel margins are supported.

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DIRECTION OF RODS

• If the discs are cut in an oblique plane, the bundles of rods seem to interwine more irregularly.

• Its optical appearance of enamel is called gnarled

enamel.

• CLINICAL SIGNIFICANCE:-

• This enamel is not subject to cleavage as regular enamel.

• This enamel does not yield readily to pressure of hand cutting instruments.

HUNTER-SHREGAR BANDS Site: Anterior tooth- Incisal surface Posterior tooth- Cervical region Importance: Distribute and dissipate impact

forces.

ENAMEL TUFTS

These projections arise in Dentine and extend into enamel in the direction of long axis of crown, hence may play a role in spread of caries.

ENAMEL LAMELLAE

Contains mostly organic material which is WEAK AREA, therefore predisposes tooth to entry of bacteria ,hence dental caries..

Perikymata :- Transverse wave like grooves appear Transverse wave like grooves appear

to be the external manifestations of to be the external manifestations of striae of retziusstriae of retzius..

Continuous around the tooth and Continuous around the tooth and parallel to each other and to the CEJ.parallel to each other and to the CEJ.

Seen in freshly erupted teeth or in Seen in freshly erupted teeth or in tooth which is not subjected to tooth which is not subjected to abrasive forces.abrasive forces.

Average of Average of 30 perikymata/mm30 perikymata/mm in in cervical region and cervical region and 10/mm10/mm in occlusal in occlusal region.region.

These may contribute to adherance of plaque material which results in caries.

Perikymata

NASMYTH’S MEMBRANE Covers newly erupted tooth. Membrane replaced by pellicle. Microbes invade pellicle to form

plaque.

ENAMEL PEARLS Occasionally found on root

surface towards cervical margin. Importance: Predisposed to

plaque accumulation following gingival recession.

They – act as bacterial/ food traps

thickness of enamel

predispose tooth to caries.

Fissure

CLINICAL CONSIDERATION

Dental caries

Definition: dental caries is defined as a multifactorial ,

transmissible ,infectious oral disease caused primarily by the complex interaction of cariogenic oral flora with fermentable dietary carbohydrates on the tooth surface over time.

Sturdevant 6th edition

Demineralization occurs as follows

Definition White opaque chalky spots observed when

the tooth surface is desiccated are termed as incipient caries Sturdevant 4th edition

Radiographically seen as faint radiolucency

Chalky white spot

Definition: Caries which becomes static or stationary and

doesn't show any tendency for further progression

Clinically intact ,discolored ( black or brown spots )

ARRESTED CARIES

Translucent zone

Dark zone

Body of the lesion

Surface zone

For an ideal enamel wall , following are the Noy’s structural requirements-

1) The enamel wall must rest on sound dentine and all carious dentine must be removed

2)Enamel which forms cavosurface angle must have their inner ends resting on sound dentin

3) The rods which form cavosurface angle must be supported on sound dentine and their outer ends must be covered by restorative material (possibly by giving a bevel)

4) Cavosurface angle must be beveled so that the margins will not be exposed to injury in condensing restorative material against it.

1)Amelogenesis Imperfecta- Hereditary defect of enamel

Ectodermal disturbance

Genes causing Amelogenesis

Imperfecta:

• AMELX (5% cases)

• ENAM (most cases)

• MMP20

• KLK

o Defective matrix formation.o Enamel has not formed to full normal thickness

Hypoplastic type

Hypocalcified type

o Enamel is so soft that it can be removed by a prophylaxis instrument.

o Defective mineralization of formed matrix

Hypomaturation typeo Immature Enamel crystals

o Defective enamel can be pierced by an explorer point under firm pressure

1) Small teeth with short root

2) Open contact

General features of Amelogenesis Imperfecta

3) Discoloration ranging from yellow to dark brown.

4)Thin enamel

5)Enamel could look wrinkled

6)Delay in eruption

7)Occlusal surfaces and incisal edges severely abraded

8)Sensitivity

1. Enamel may be totally absent

2. Appear as thin layer, chiefly over the tips of the cusps and the interproximal surfaces.

3. Same radiodensity as dentin , it become difficult to differentiate between two

Radiographic features

Treatment

1)Full veneering

2)Selective odontotomy esthetically reshaping the teeth.

II)Enamel Hypoplasia

Incomplete or defective formation of the organic matrix

Causes:1.Nutritional defect2.Exanthametous diseases3.Congenital syphilis4.Ingestion of fluoride

1) Hutchinsons incisors(screw driver shaped central incisors)

2) Mulberry molars(small globular masses of enamel on occlusal surface)

Hypoplasia due to syphilis

Treatment

•Selective odontotomy and esthetic reshaping of the tooth enamel

•Metallic restorations

•Bleaching

Tetracycline Generalized type of intrinsic stain

When the tetracycline is administered during the time of enamel formation it forms a complex chelating compound with the organic and inorganic components of the enamel. The created compound is very stable.

Discoloration depends upon: Dosage Length of time over which administration occurred Form of tetracycline

According to Moffitt:

Critical period for tetracycline induced discoloration in deciduous dentition

• 4 months in utero to 3 months postpartum

(maxillary and mandibular incisors)

• 5 months in utero to 9 months postpartum (maxillary and mandibular canines)

In permanent dentition• 3-5 months postpartum to 7 yrs of age

Discoloration varies from yellow –orange to dark blue

Drugs:Chlortetracycline –grayish stains

Minocycline –grayish discoloration

Oxytetracycline –yellow stains

Treatment

Conservative methods:I. Bleaching

I. Microabrasion

II. Macroabrasion

III. Veneering

Fluorosis

Generalized intrinsic stain

Chronic ingestion of flouride ions interfers with ameloblast function during formative stage of tooth development and disturb their activity

Clinical features

1) Mild changes• White flecking or spotting of enamel

2)Moderate to severe changes

•Brown staining of surface•Pitting•Tendency of enamel to fracture

Treatment

Conservative methods:I. Bleaching

I. Microabrasion

II. Macroabrasion

III. Veneering

Discoloration:

Can occur due toExtrinsic factors: 1. Tobacco/tea stains2. Poor oral hygiene3. Food colors4. Gingival bleeding5. Existing restorations6. Chromogenic bacteria

Intrinsic factors:

1. Caries. 2. Fluorosis.3. Tetracycline and other drugs.4. Age changes.5. Non vital teeth6. Internal resorption.7. Hereditary disorders.

DISCOLORATION

EXTRINSIC DISCOLORATIONS Avoidance of the foods and beverages that cause

stains Using proper tooth brushing and flossing

techniques Professional tooth cleaning: Some extrinsic stains

may be removed with ultrasonic cleaning , enamel microabrasion, enamel macroabrasion

INTRINSIC DISCOLORATIONS Bleaching Enamel microabrasion Enamel macroabrasion Veneering

Definition: Surface tooth structure loss resulting from

direct frictional forces between contacting teeth . (Marzouk 1st edi)

Types of Attrition1.Occluding surface attrition2.Proximal surface attrition

Causes 1. Tooth to tooth contact2.Parafunctional mandibular movements

Clinical features1. Sensitivity2. Flattening of incisal and occlusal surface3. Flattening of inclined planes4. Flattening of proximal contact areas5. Facet formation6. Reverse cusp7. Loss of vertical dimension of teeth8. Decay at occluding areas9. Angular chelitis10.Cheek bite 11.Temporo mandibular problems

Flattening of incisal

Treatment1. Para functional activities should be

controlled with protecting occlusal splints.

2. Endodontic therapy for pulpally involved teeth

3. Occlusal equilibration, by selective grinding of tooth surfaces

4. Restorative modalities(only metallic restoration)

Abrasion

Definition: Surface loss of tooth structure resulting

from direct friction forces between teeth and external objects, or from frictional forces between contacting teeth components in the presence of an abrasive medium.

Causes1. Improper use of tooth brush2. Improper use of tooth pick and dental floss3.Habitual opening of bobby pins with teeth.4.Use of abrasive dentifrices

Marzouk 1st edition

Clinical features1. Linear in outline(following path of brush

bristles)

2. Angular peripheries

3. Notching of central incisors

4. Wedge shaped ditch on proximal exposed root surface

Treatment1. Diagnosing the cause2. Removing the causative factor(habits)3. Desensitizing exposed dentin(if tooth is

sensitive)4. Restorative treatment

Definition Loss of tooth structure resulting from

chemico-mechanical acts in the absence of specific microorganisms Marzouk 1st edition

Causes1. Ingested acid(lemon and citrus fruits)2. Chronic vomiting3. Frequent regurgitation

Rate of erosion is 1micron per day

Erosion

Clinical features

1. Shallow, broad, smooth ,highly polished, scooped out depression on the enamel surface adjacent to cementoenameljunction

2. Confined to gingival third of labial surface

Treatment1. Complete analysis of diet, chronic vomiting,

environmental factors should be performed

2. Restorative treatment (tooth colored material can be used with

minimal or no tooth preparation)

AbfractionDefinition: Strong eccentric occlusal force resulting in

microfractures at the cervical area of tooth causing wedge shaped defects

Sturdevant 6th edition

Causes Heavy force in eccentric occlusion

Clinical feature Wedge shape defect Defect has smooth surface

Treatment Restoration

Age changes & Clinical considerations

•Attrition is seen in aged people.•Wear facets are common.•Decrease in vertical dimension and flattening of proximal contours.•Color changes with age.•Permeability decreases.•Caries incidence is less in aged people.•Surface composition: more amount of fluoride and localized increase in nitrogen.

Fluoridation

It decreases the solubility of enamel It acts in the following way:I. Forms fluoroapatite which is less soluble

than hydroxyapatite

II. Inhibits demineralization

III.Enhances remineralization

IV.Inhibits bacterial metabolism

Acid etching

ACID ETCHING TECHNIQUE- Buonocore in 1955

Micromechanical bonding b/w enamel and resin based restorative material.

Mode of action-

Increases the porosity of exposed surfaces by dissolution of crystals - creates a micro porous layer from 5 to 50 µm deep

Three etching patterns predominate:-

(Preferential removal of rods)

TYPE II

TYPE III

(Junction b/w type 1 n type 2)

(Preferential dissolution of prism core)

TYPE I

Enamel etching transforms the smooth enamel surface into an irregular surface

Etched enamel has high surface energy (72 dynes\cm) allow resin to wet the tooth surface better when resin penetrates into micro porosities and polymerized to forms resin tags

Resin tags interlocked with the surface irregularities created by etching which form mechanical bond to enamel.

Bond strength:16-20Mpa

Originally recommended 60 secs using 37% phosphoric acid.

Currently,etching time for most etching gel is 15 sec

Aprismatic enamel requires double the etching time required by prismatic

Etching time

Involves the surface dissolution of enamel by acid along with the abrasiveness of the pumice to remove superficial stains or defects

Commercially developed system for enamel microabrasion. [PREMA (Premier enamel micro abrasion)

Enamel microabrasion

In 1984 Mc Closkey reported this techniqueIn1986 Croll and cavanaugh modified this technique

PREMA contains a reduced concentration of hydrochloric acid (approx 11%)+ silicon carbide particles in a water soluble gel paste.

Mode of action 1. Physical removal of stained outer enamel

layer by stripping action of acid and abrasive action of pumice

2. The etching action removes interprismatic substance and changes light refraction characteristics

3. There is oxidation of some pigments

Procedure

Removal of localized superficial white spots and other surface stains or defects is called macroabrasion

Sturdevant 6th edition

12 fluted composite finishing bur or fine grit finishing diamond in a high speed handpiece is used

Macro abrasion

Procedure

CONCLUSION

Enamel is an important structural entity of the tooth hence its protection is utmost important.

Its function is to form a resistant covering of the teeth, rendering them suitable for mastication.

Marzouk : Operative Dentistry, First Edition

Orban :Oral Histology and Embryology,Tenth Edition

Oral pathology SHAFER’S Sturdevant :Art and Science of Operative

Dentistry, Fifth and sixth Edition

Ten Cates: Oral Histology , Seventh Edition Enamel microabrasion,theodore p croll