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CONTACTS AND

CONTOURS

Contacts and Contours

Dr.Ruchir Kapur

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Definition

Contact area : Contact areas are the places on the proximal surfaces of tooth crowns where a tooth touches the tooth adjacent to it in the same arch when the teeth are in proper alignment.

Contours : Convexity on facial and

lingual surfaces that affords protection and stimulation of supporting tissues during mastication.

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Contact point : refers to the occlusal cusp of a tooth that touches the occlusal portion of another tooth in the opposing arch.

Embrasures : (spillways)• “V” shaped spaces that originate at the proximal

contact areas between adjacent teeth and are named for direction towards which they radiate.

• Incisal • Occlusal• Gingival

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Proximal contact areas and contours

Proximal contact area : Area of proximal height of contour of mesial or distal surfaces of a tooth that touches or contacts its adjacent tooth in the same arch.

Location :

In anterior teeth : Located closer to the incisal surface of the teeth.

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In posterior teeth : Located near the junction of incisal and middle thirds or in the middle third.

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According to their general shape

Tapering teeth

Ovoid teeth.Square teeth

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Tapering teeth : Incisors :• Inciso apically- starts near incisal

edges.• Labio lingually- slightly labial to

incisal edges.

Canines : Very angular• Mesial contact- close to incisal

edges • Distal contact- center of the distal

surface.

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Premolar : Angular.• Crowns constricted cervically with long cusps.• Taper lingually , contact area occur bucally-at

buccal axial angle.• Contacts begin 1 mm gingivally from crest of

marginal ridges.• At junction of occlusal and middle 3rd of crown.

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Molar : Mesial contacts :• Bucco-lingually : mesio-buccal axial angle of the

tooth.• Occluso-gingivally : at distance 1/3rd to ½ from

the occlusal surface to C.E.J.• Distal contacts : • Bucco-lingually : shift lingually to the middle

third.• Occluso-gingivally : at middle third.

Lingual shifting of contacts - prominent in mandibular molars.

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Embrasures :Anterior : • Incisal and labial - negligible.• Gingival and lingual - largest and widest.

Posterior :• Buccal – small.• Occlusal - wide and deeper.• Gingival & lingual - wide and broad.

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Proximal contour :

Common feature : • Starting at CEJ, surface presents concavity to

contact areas , and convex from there to crest of marginal ridges.

• Concavities are pronounced on mesial surface.• Most frequently- teeth with buccal and lingual

roots.• Most pronounced on mesial of maxillary 1st

premolar.

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Square teeth : Bulky & angular, little cervical constriction & proximal surfaces devoid of curves.

Incisors : • Incisally – at incisal ridge.• Labio lingually – in a line with incisal

edge.

Canines :• Incisally – close to incisal ridge.• Labio lingually – in a line.

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Premolar : broad contacts , short cusps.• Bucally : towards buccal axial angle (buccal 3rd).• Occlusally : at occlusal 3rd.

Molar : • Mesial contact : Crowns tapered lingually.• Bucco-lingually : buccally -buccal axial angle.• Occluso-gingivally : From a mere line contact to half

the height of crown.• Distal contact : • Bucco-lingually : midline of crown.• Occluso-gingivally : occlusal third.

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Embrasures :• Incisal, labial, occlusal - Nil.• Gingival embrasure - barely noticeable, or may

extent 1/3rd height of crown.• Buccal embrasure -when present, very narrow &

flat.• Lingual embrasure - Narrow or wide.

Proximal contour :• Plane instead of curved.• Bucco-lingual concavities : may be on mesial

surface of max. 1st premolars, 1st & 2nd molars, mesial surface of mand. 1st molar.

• Distal surfaces are flat or slightly convex.

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Ovoid teeth : Transitional type, surfaces primarily convex.

Incisors :• Labio-lingually : lingual to incisal

ridge.• Mesial contacts : start at 1/4th of

crown (Inciso gingivally).

• Distal contacts : start at 1/3rd – ½ of crown.

Canines : • Incisally close to incisal ridges.

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Premolar : • Short cusps.• Convexity of marginal ridge carries the contacts

almost to the middle third.

Molars : • Mesial contacts – at junction of buccal and middle

third of the crown.• Distal contact – in line with central groove on the

occlusal surface.

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Embrasures : • Labial, incisal & buccal embrasure -larger.• Gingival & lingual embrasure -shorter &

broad.

Proximal contour : • Convex from incisal angle to cervix.• Premolar : bell shaped.• Molars : mesial surface is convex.

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Marginal Ridges

Elevated rounded ridges located on mesial and distal edges of occlusal surface of tooth.

Should be formed in two planes bucco-lingually, meeting at very obtuse angle.

This specification is essential for : The balance of the teeth in the arch. Prevention of food impaction proximally. Protection of the periodontium. Prevention of recurrent and contact decay. For helping in efficient mastication.

With age marginal ridges and occlusal embrasures are reduced, due to vertical occlusal attrition and proximal flattening of contact areas.

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Facial and lingual contours

Cervical ridge. Extend not more than 1mm beyond cervical line. On labial, buccal & lingual of maxillary teeth &

buccal of mandibular posterior - uniform. Average curvature about 0.5mm or less. The canines have more curvature than central

and lateral incisors. Mandibular anterior - <0.5mm. Mandibular posterior (lingually) - 1mm with crest

of curvature at middle 3rd instead of cervical 3rd.

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In molars since there are more than one cusp the convexities are interrupted by concavities at occlusal ½ - 2/3rd of the crown.

Upper anterior teeth concavities determinant for mandibular movement.

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Hazards of faulty reproduction of features of

teeth in restorationsContact size : Creating a contact area

i.e. too broad, bucco-lingually or occluso-gingivally.

• Produces an interdental area that is less cleanable.

Creating a contact area i.e. too narrow, bucco-lingually or occluso-gingivally.

• Food is impacted vertically and horizontally on col area.

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Open (loose) contact.• Creates continuity of the

embrasures with each other and with the interdental col.

All of these defects will allow food impaction

and accumulation of bacterial

plaques, with accompanying

periodontal problems and

caries.

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Contact configuration : Contact area i.e. flat (deficient convexity) can

make it broad bucally, lingually, Occlusally, and /or gingivally.

Contact with excessive convexity will diminish the extent of contact area.

Concave contact area in a restoration.• Occurs restoring adjacent teeth simultaneously.• Adjacent restoration with convex proximal surface

. • Interlocking between the concavity and convexity

can immobilize the contacting teeth.

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Contour :

Facial and lingual convexities :• More danger in overconvex facial and lingual

surface.• Can create undisturbed environment for

accumulation and growth of cariogenic and plaque ingredients at gingival margin.

• No apparent hazards from underconvex curvatures.

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Facial and lingual concavities :

• Concacavities occlusal to height of contour- involved in occlusal static and dynamic relations.

• Deficient or mislocated concavities- premature contacts, that inhibit physiological capabilities of mandibular movements.

• Concavities apical to height of contour - essential for maintenance of accompanying new components of adjacent periodontium.

• Deficient concavities lead to overhanging restoration.

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Marginal ridges : Absence of a marginal ridge in the restoration.

Marginal ridge with an exaggerated occlusal embrasure.

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Adjacent marginal ridge not compatible in height.

Marginal ridge with no occlusal embrasure.

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A marginal ridge with no triangular fossa.

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A one-planed marginal ridge in the bucco-lingual direction:

• Creates premature contacts during functional and static occlusion.

• Increases depth of adjacent triangular fossa magnifying stresses in this area.

• Increase height of marginal ridge in center, making it amenable to adverse effects of horizontal components of force.

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A thin marginal ridge in its mesio-distal bulk.

Marginal ridges not compatible in dimension or location with the rest of the occluding surface.

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Procedures for formulations of proper contacts and contours

I. Tooth movements. II. Matricing.

I .Tooth movements :• Act of either separating the involved teeth from

each other, bringing them close to each other or changing their spatial position in one or more dimension.

Objectives. Bring drifted, tilted or rotated teeth to their

indicated physiological positions.

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Close space between teeth not amenable to closure by contemplated restoration.

Move teeth to another location, so when restored will be in position most acceptable by periodontium.

Move teeth Occlusally or apically.

Move teeth from non-functional or traumatically functional location to a physiologically functional one.

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Move teeth so that when restored, they may be in most esthetically pleasing position.

Move the teeth in location to increase dimensions of available tooth structure for resistance and retention forms.

Create space sufficient for matrix band interproximally.

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Two principle methods of tooth movements / separation.

Rapid or Immediate tooth movement / Separation.

Slow or Delayed tooth movement / Separation.

Rapid or Immediate tooth movement / Separation.

• Mechanical type of separation that creates, either proximal separation at point of separators introduction and / or improved closeness of proximal surface opposite the point of separators introduction.

• Can be used preparatory to slow movement or maintain space gained by it.

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• Should not exceed 0.2 – 0.5 mm.

Achieved by two principles :

Wedge method

Traction method

Wedge method :• Separation is achieved by placing pointed wedge

shaped device between the teeth and slowly inducing pressure in order to create space at the contact area.

• Ex : Elliot separator, wedges.

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Elliot separator/ crab claw separator /

Single bow separators :

Indications:• Short duration separation that does not

necessitate stabilization.• Examining proximal surfaces or in final polishing

of restored contacts. Procedure:• Adjust the two opposing wedges of the separator

interproximally gingival to the contact area. • Move the knob clockwise so that the wedges

moves towards each other establishing desired separation.

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Wooden or plastic wedges

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Wooden wedges :

• Easily cut & Trimmed • Absorb moisture intra orally to swell and expand

slightly, thus improve proximal retention of band .• Relatively flexible .• Economical. • Example : Orangewood, Hemowedges

Maplewood, pine (soft) ,Oak (hard)

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Plastic / Resin Wedges :

• Opaque/ Transparent• Can be plastically molded and bent to correspond

with the configuration of interdental col.• Can transmit light , suitable for light cured

restorations.• Relatively rigid hence easy tooth separation.

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Functions :

Assure close adaptability of matrix band to tooth, gingival to the gingival margin of preparation.

Occupy space designated to be the gingival embrasure.

Create some separation to compensate for thickness of matrix band.

Assure immobilization of the matrix band.

Protect interproximal gingiva from trauma.

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Wedging techniques

Piggy back wedging : Indications –

• Gingival recession.• Shallow proximal box.

Small wedge “piggy back” is used over the first wedge to ensure proper contour.

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Double wedging :

Indication :• Spacing between the adjacent teeth.• Wide proximal box in buccolingual dimensions

• Two wedges, one from buccal aspect and one from lingual aspect.

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Wedge wedging :

Indication :• Concavity present on proximal surface.

• Second wedge is inserted between first wedge and band so that opening is eliminated and the matrix band is well adapted to the gingival margin of the prepared cavity.

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Slow or Delayed tooth movement / Separation.

Indication - tilted and/or drifted teeth. Methods : Separating wires. Orthodontic appliances.

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Matrices

Defination : Device that is applied to a prepared tooth before the insertion of the restorative material to assist in development of appropriate tooth contours and in order to confine the restorative material excess.

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Ideal requirements :

Should replace the missing wall temporarily .

Should be easily inserted and removed .

Should be sufficiently rigid to retain contour given to it.

Should not react or adhere to the restorative material .

Should resist the condensation pressure.

Should be comfortable for the patient .

Should be small and handy so that access and visibility is not affected.

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Objectives :

To act as a temporary wall of resistance during insertion and hardening of the material.

To displace or retract gingiva and rubber dam.

To achieve dryness and non-contamination of operating field.

To resist and compensate for dimensional changes that occur during setting.

To maintain natural contact and contours .

To promote health of inter dental gingiva by preventing overhanging restorations.

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Classification of matrices : Based on mode of retention :

Mechanical retained matrices :

• Ex : Tofflemire, Ivory no.1 and 8.

Self retained matrices :

• Ex : Black’s matrix and copper band supported

by impression compound.

• 1

• 2.

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Gillmore’s classification : Custom made : • Prepared by dentist or assistant suitable size

matrix is cut and impression compound placed in the place of wedge.

Mechanical :• Tofflemire, Ivory no. 1 and 8.

Miscellaneous : • T-Band, soldered band, seamless copper band,

orthodontic band, blacks matrix.

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Types of matrices

Ivory No. 1

• Band encircles one of posterior proximal surfaces, indicated in unilateral Class II cavities.

• Band is attached to retainer through wedge shaped projections which engage tooth through embrasures of unprepared surface.

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Ivory No. 8 :

• Band encircles entire crown.

• Indicated for bilateral class II cavities.

• Circumference of band can be adjusted by adjusting screw.

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Tofflemire

• Universal matrix.• Designed by B.R.Tofflemire.• Indicated -3 surfaces of posterior tooth have

been prepared.• Commonly used for two surfaces class II

restorations.• Bands are available in 2 thickness :• 0.05 mm• 0.038 mm

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Advantages : Can be used both from facial / lingual side. Economical. Provides good contacts and contours. Can be easily removed.

Types :• Straight .• Contra angle.

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Procedure

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Black matrix

By Dr. G.V.Black. “Ligated matrix band”.• One of earliest custom-

made matrices.• Thin metal plate (copper,

brass, German silver, or stainless steel) used as a matrix.

• Band must encircle about ½ of tooth.

• Ligature wrapped 2 or 3 times around the tooth, including matrix band and tied.

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Automatrix

Retainerless matrix system. Types of bands :• 3/16 inch (4.8 mm) wide, 0.002 inch thick.• ¼ inch (6.35 mm) wide, 0.002 inch &

0.0015 inch thick.• 5/16 inch (7.79 mm) wide, 0.002 inch

thick.

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Indications

• Complex amalgam restorations-one or more cusps to be replaced.

Advantages

• Convenient.• Improved

visibility due to lack of a retainer.

• Autolock loop can be positioned facially or lingually.

• Rapid application.

Disadvantages

• Bands are flat-difficult to burnish.

• Cannot develop proper contacts and contours.

• Expensive.

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Copper band matrix

• Assorted sizes make excellent matrices.

• Cylindrical shape.• Bands are heated to redness

in flame & quenched alcohol.• With contouring pliers band is

contoured.• Festooned with scissors so,

gingival periphery of it corresponds to gingival curvature & CEJ.

• To stabilize, wedges are placed.

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Indications•Badly broken teeth.•Class II cavities with large

buccal or lingual extensions.

Advantages•Provide excellent contour.

Disadvantage•Time consuming.

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Plastic matrix strips

• Transparent plastic strips.• Celluloid strips(cellulose nitrate) –

silicate cements.• Cellophane (cellulose acetate) –

resins.• Mylar strips for composite and

silicate restorations.• Band should extend at least 1mm

beyond gingival & incisal margins of cavity, can be stabilized by wedge.

• After inserting composite resin material the matrix is pulled tightly around tooth following which light curing is done.

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• Once restoration is completed, wedge can be removed & matrix strip slid out of the proximal surfaces of the contacting teeth.

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T band matrix

• Preformed T shaped stainless steel matrix band without retainer.

• Long arm of ‘T’ is bent to surround tooth circumferentially.

• Overlaps short horizontal arm of ‘T’ which is bent over long arm and helps to retain shape.

Indication :• Class II cavities. Advantages :• Simple and inexpensive.• Rapid and easy to apply Disadvantages :• Flimsy in structure, not very stable.

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Compound supported matrix

Custom made matrix / Anatomic matrix. 5/16th inch wide, 0.002 inch thick stainless steel

band used. Contoured with an egg-shaped burnisher. Band is stabilized by softened impression

compound.

Indication : For restoring class II cavities involving one or

both proximal surface. For complex situations like pin-amalgam

restoration.

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Advantages :

Highly rigid and stable. Provides good access and visibility Most efficient means of reproducing contact

and contour.

Disadvantages :

Time consuming.

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Precontoured sectional matrix strips

• Small, Precontoured dead soft metal matrices ready for application.

• Selected according to tooth to be restored.

• Band held by a flexible metal ring -Bitine ring.

• E.g. Palodent matrix system (by Dentsply) , Triodent matrix system.

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Indication :• Class II cavities.• Amalgam and composite restorations.

Advantages :• Ease of application.• Provide better proximal contours for posterior

composite restorations.

Disadvantages :• Expensive.

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Conclusion

“ We as a clinician or a restorative dentist should have an adequate knowledge of the anatomical & functional aspects of contacts & contours so as to reproduce them with ideal restorative material, which in turn will help to maintain the oral cavity in sound health”…….

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References

Sturdevant’s Art and Science of Operative Dentistry : 5th edition, South Asian edition.

Operative dentistry : Modern theory and practice , Mohamed A Marzouk.

Text book of operative dentistry, Nisha Garg, Amit Garg.

Wheeler’s Dental Anatomy, physiology, and occlusion : 8th edition.

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