CONTACTS AND CONTOURS

By: zool khader shabana

IDEAL CONTACT & CONTOUR

• Conserve the health of the periodontium.

• Prevents food impaction.

• Makes the area self cleansable.

• Improve the longevity of proximal restorations.

• Maintain the position of the tooth in the dental arch.

Tapering teeth Square teeth Ovoid teeth

EMBRASURES

Embrasures are V-shaped spaces that originate at the

proximal contact areas between adjacent teeth and are

named for the direction toward which they radiate.

These embrasures are: (1) facial, (2) lingual,

(3) incisal or occlusal, and (4) gingival

FUNCTIONS

• Makes spillway for escape of food during mastication, thus decrease forces brought to bear upon the teeth during the reduction of

any material that offers resistance.

• Prevents food from being forced through contact area, thus keep food from being packed between the teeth.

• Reduce the forces of occlusal trauma brought to bear at the teeth thus dissipate and reduces occlusal forces.

• Permit slight amount of stimulation to the gingiva by frictional massage of food, thus protecting gingiva from undue trauma .

HAZARDS OF FAULTY EMBRASURES

• Decrease or absent : Additional stress created in the teeth and supporting structures during mastication

• Too large : Little protection to the supporting structures as food is forced into the interproximal surface by an opposing cusp .

CONTOURS

The facial and lingual surfaces possess

some degree of convexity that affords protection and

stimulation of the supporting tissues during mastication

Arrows show pathways of food passing over facial surface of mandibular

molar during mastication.

A, Overcontour deflects food from gingiva and results in understimulation of

supporting tissues.

B, Undercontour of tooth may result in irritation of soft tissues.

C, Correct contour permits adequate stimulation for supporting tissues, resulting in

healthy condition.

MARGINAL RIDGES • It should always be formed in two planes

buccolingually, meeting at very obtuse angle.

• Functions :

Balance of teeth in the arch .

Prevention of food impaction proximally.

Protection of periodontium .

Helps in efficient mastication .

Some marginal ridges function as working occluding cuspal

elements .

CLINICAL SEQUELAE OF FAULTY

CONTACTS & CONTOURS

•Food impaction / retention

•Gingival recession

•Gingival inflammation

•Fractured restoration

•Faculty occlusion

•Gingival irritation

•Periodontal complication - acute abscess or bone loss.

•Shifting of teeth (mesial drift).

Procedures for formulation of proper contacts and contours. Intra oral procedures Extra oral procedures Tooth movement matricing wax pattern

cast adjustment Rapid or immediate slow or delayed

Separating wires Wedge method Wood or plastic Ferrier double bow separator

Traction principle Over sized temporaries Elliot separator Orthodontic appliances

INTRA ORAL PROCEDURES

Tooth movement

• It is the act of either separating the involved teeth from each

other, bringing them closer to each other and / or changing their

spatial position in one or more dimensions.

• Objectives

Rapid or immediate tooth movement

Wedge method

Wood or plastic Elliot separator

Traction principle Non interfering true separator Ferrier double bow separator

Elliot separator

Wedge method

Non interfering true separator

1 2 3

Ferrier double bow separator

Slow or delayed tooth movement

•Separating wires

•Oversized temporaries

•Orthodontic appliances

MATRICING

• Matrix system - Matrix band, Retainer & Wedges.

• It is the procedure where by a temporary wall is created opposite to axial walls & surrounding areas of tooth structure that were lost during preparation.

Ideal requirements of a matrix band

Ease of application

Removability

Rigidity

Versatility

Height

Proximal contours

Positive proximal pressure

Should not react / adhere to the restorative material.

Functions Of Matrix Band Act as a temporary wall.

Re-establishment of contact.

Restrict extrusion of the restorative material and prevents overhangs.

Provide physiologic contour for proximal surface of restoration.

Assist in holding back gingiva & rubber dam during restoration.

Maintain the form of restoration during hardening.

CLASSIFICATION OF MATRIX SYSTEMS

Based on the material Based on the material

Non metallic matrix Metallic matrixNon metallic matrix Metallic matrix

Ex Mylar strip Ex Mylar strip

Haweno’s plastic Haweno’s plastic

Cervical matrixCervical matrix

cellulose acetatecellulose acetate

(cellophane)(cellophane)

cellulose nitratecellulose nitrate

(celluloid) (celluloid)

With retainerWith retainer

(mechanical) (mechanical)

Ex Ivory no 1& 8Ex Ivory no 1& 8

Tofflemire matrix band Tofflemire matrix band

With out retainerWith out retainer

(anatomical)(anatomical)

Auto matrix ,T-band,Auto matrix ,T-band,

S –band ,Soldered band,S –band ,Soldered band,

Compound supported Compound supported

matrix, Blacks matrix,matrix, Blacks matrix,

Copper band , AnatomicCopper band , Anatomic

matrixmatrix

• Based on anatomic contour

Anatomic matrix

Non anatomic matrix

• Based on material used

Metal

Copper

Brass

Celluloid

• Based on the support

Compound supported

Non compound supported

• Based on the dentition Deciduous Permanent

• Based on the retainer Automatrix Matrix with retainer

• Based on shape or design Straight Contra angled.

• Based on the position Circumferential Unilateral

Matrices for individual cavity preparation

Matrices for class -I cavity designs 4,5,6,7,& 8 preparation

- Double banded Tofflemire matrix

Matrices for class –II

1 Single banded Tofflemire [design 1,2,3,6,7,&8]

2 Ivory matrix No 1 [unilateral class -2]

3 Ivory matrix No 8 [Designs 1,2, & 3]

4 Black’s matrices [Designs 1,2 &3]

5 Soldered band (or) seam less copper band matrix

[Design 6,7,&8]

6 The anatomical matrix [Design 1,2,3,6,7 & 8]

7 Roll –in band matrix [Auto matrix]

8 S – shaped matrix band [Design 4,5,&7]

9 T-shaped matrix band

3) Matrices for amalgam restoration on the distal of the cuspid

a) S- shaped matrix

b) Tofflemire matrix

4) Matrices for class III –direct tooth colored restorations

a) For silicate cements – celluloid strips ,mylar strips .

b) For resins – cellophane strips , mylar strips

c) T – shaped matrix band

5) Matrices for class –IV direct tooth colored restorations

a) Plastic strip for inciso –proximal cavities

b) Aluminium foil incisal corner matrix

c) Transparent crown form matrices

d) Anatomic matrix

e) Modified S – shaped band

6) Matrices for class -V amalgam restorations

a) window matrix

b) S –shaped matrix

7) Matrices for class- V direct tooth colored restorations

a) Anatomic matrix for non – light cured materials.

b) Aluminum (or) copper collars for non – light cured materials .

c) Anatomic matrix for light & non- light cured materials

Materials used as matrices

• Stainless steel

• Platinum plate

• Brass

• Copper

• Tin

• Cellulose acetate (cellophane)

• Cellulose nitrate (celluloid)

• Polymer materials

Matrices are commonly supplied as

• Width - 1/4 ",3/8 ",5/16 " (or) 1/8".

• Thickness - 0.002 inch (0.05mm) &

0.0015 inch (0.038 mm)

Height should be :

occlusally – 1-2 mm above the marginal ridge

gingivally – 1mm below the gingival margin.

Tofflemire matrix/ universal matrix

Large Knurled nut

Small knurled nutHead

Locking vise

Slots Pointed Spindle

– Always be sure that the slotted end of the vise is facing gingivally.

– Ideally, the retainer should be parallel and adjacent to the facial surfaces of the quadrants of teeth being operated on.

Two techniques : - Single banded - Double banded

MATRIX BURNISHING

With band on pad ,use small burnisher to deform band

Use large burnisher to smooth band contour

The convex side of a spoon excavator is used to impart a convex contour to the matrix band

TOFFLEMIRE MATRIX SYSTEM REMOVAL

Removal of the handle stabilizing the band with the fingers while releasing the knob insures against fracture of the soft amalgam

Removal of band in angular direction

IVORY MATRIX NO.1

IVORY MATRIX NO. 8

Anatomical matrix

ROLL –IN BAND MATRIX (AUTOMATRIX)

Matrices For Tooth colored restoration

WEDGES

Natural eg: woodNatural eg: wood PreformedPreformed

Synthetic eg: plasticSynthetic eg: plastic Custom madeCustom made

MedicatedMedicated RoundRound

Non medicatedNon medicated TriangularTriangular

It is a wooden or plastic device placed interproximally which approximates the band on to the tooth and prevents gingival overhang of restoration.

Classification of wedgesClassification of wedges

BASED ON MATERIALBASED ON MATERIAL

PLASTIC WOODENPLASTIC WOODEN

BASED ON SHAPE BASED ON SHAPE

ROUND TRIANGULAR ROUND TRIANGULAR

BASED ON BASED ON MODIFICATIONMODIFICATION

Modified UnmodifiedModified Unmodified

METALMETAL

1 They assure close adaptability of matrix band to the tooth, gingival to the gingival margin of preparation. This will prevent gingival overhangs of the restorative material.

2. Protects the interdental col by preventing restoration impingement.

3. Defines the gingival, facial & lingual extent of the contact area.

4. Creates some separation to compensate for the thickness of matrix band .

FUNCTIONS OF WEDGES

5. Establishes a traumatic retraction of the rubber dam and the

gingiva, there by producing a temporary hemostasis and

minimizing moisture by adsorption

6. Assure immobilization of matrix band during restoration

placement.

7 The wedges can be impregnated with haemostatic solutions to

obtain hemostasis during restorations.

Advantages of wooden wedges• Easily cut & Trimmed .

• Absorb moisture intra orally to swell and expand slightly, thus improving proximal retention of band.

• Relatively flexible .

• Economical.

- Example : Orangewood, Hemowedges Maplewood, pine(soft) Oak (hard)

Plastic /Resin wedges- Opaque / Transparent

• Can be plastically molded and bent to correspond with the configuration of interdental col.

• Transparent plastic Wedges can transmit light through, suitable for light cured restorations.

• Relatively rigid hence tooth separation occurs easily

• example Luci wedges

Round wedge

• Preferred in conservative Preferred in conservative Class II preparations.Class II preparations.

Triangular wedgeTriangular wedge

• Preferred with class II Preferred with class II preparations preparations with deep gingival with deep gingival margins because of margins because of greatest width at its basegreatest width at its base

Criteria to be followed for

wedge selection

Not all cavities need to be wedged .

A gingival floor placed on a convex proximal surface example -lower 2nd bicuspid, does not need a

wedge.

Milder or flatter convexity - should be braced with a wedge

Flat and concave surface - require wedging

Wedges must not restrict the band from bulging outward to develop a good contact point.

• Wedge placed high - large gingival embrasure. Interfere with the development of a physiologic contact point.

• Wedges must be fitted and customized.

There is no universal wedge, and each one must be fitted for its individually intended space. Trimming can be accomplished by as scalpel, a gold knife or a diamond stone.

Rationale for tooth separation by wedge placement

• Based on tooth movement which utilizes the elasticity of the periodontal ligament when separated by an interdental wedge. This will also compensate for the width (Thickness) of the matrix band, so that after removal of the wedge and matrix, the separated teeth returns to its original position creating a perfect contact relation.

• Provides adaptation of matrix band in the cervical region.

• Protection from moisture and prevention of excess restorative material which could cause periodontal damage.

Types and techniques of wedge placement

• Single wedge

length -½ inch

• Double wedging techniques

* Double wedge technique

* Piggy back wedging technique

* Wedge wedging technique

Single wedge

• Depending on the location of contact, embrasure size and shape, a single wedge may be placed on lingual or buccal side

Double wedging

Indications:

- Wide faciolingual embrasures.

- When the proximal box is wide faciolingually .

Piggy-Back wedging

when wedge is significantly apical to the gingival margin, a

second wedge usually, smaller is piggy backed on the first.

Indication : when proximal box is shallow gingivally or inter Indication : when proximal box is shallow gingivally or inter proximal tissue level has receded or bothproximal tissue level has receded or both

Wedge wedging

When concavity is present on the proximal surface gingivally of the contact and extending as a fluting on to the root (mesial aspect of maxillary first premolars).