SEMINAR ON

CONTACTS AND

CONTOURSPresented By

Sahal Abu

Final Year BDS

• Introduction

• Contours

• Contours of the facial and lingual surface

• Problems of over or under contouring of the facial and lingual surface

• Contours on the proximal surface

• Proximal contact

• Importance of contact

• Size of contact

• Embrasures

• Procedures for developing correct contact and contour

INTRODUCTION

A healthy dentition comprises of fully erupted teeth withproper occlusal and proximal contacts that help to stabilizeand maintain the integrity of the arch . All the teeth havetendency toward mesial drift ,which is primarily resisted bycontact point of adjacent teeth. Decay in the proximalsurface occurs mainly due to faulty inter-relationship betweencontact area ,marginal ridges, embrasures, and gingiva. Aclinicians role is to re-establish the original or correct thefaulty contact to form physiologically stable contact &inabilty to restore this relationship disrupts harmony andcan result in deleterious consequences like food impaction,caries,drifting ,tilting or rotation of teeth.

CONTOURS

All teeth have some specific convexity on the facial ,lingual , proximal and occlusal surface of teeth that afford the protection and stimulation of the supporting tissues during mastication. This convexity are called contours.

TYPES

Faciolingual contour

Proximal contour

Occlusal contour

Contours on the facial and lingual surface

• Facial surface - cervical one third of all teeth

• Lingual surface - cervical one third of incisor and canines

-Middle one third of the premolar and molar

Problems of over or under contouring of

the facial and lingual surface

Over contoured restoration They deflect food from the gingiva causing poor gingival stimulation. The gingiva become flabby ,red and chronically inflamed due to increased plaque retention

Under contoured restoration This result in irritation and trauma to the attachment apparatus.

Contours on the proximal

surfaceTeeth show convexities on the distal and mesialsurface. The area with maximum convexity on the proximal surface is called the proximal height of contour. Proximal height of contour responsible for the creation of the

a)Proximal contact b)Embrasure space

Proximal contact

• Proximal convexity of the teeth create area of contact between adjacent teeth with in the same arch. These are called proximal contact area. Initially as teeth erupt the teeth contact each other at a point(point contact). With the passage of time, physiologic tooth movement causes frictional wear enlarging the contact point to contact area.

Importance of contact

Preserves the stability and integrity of the arch by maintaining normal mesio distal relation ship of teeth.

Prevent food impaction interdentally

Protect the soft tissue from periodontal disease

conserve the teeth from proximal caries

Premature restorative failure does not occur if stable proximal contact is present.

Size of contact

• Anteriorly- contact point

• Posteriorly –contact area about 1.5-2mm

• LOCATION OF CONTACT

Anterior teeth – incisal one third

Posteriorly - junction of incisal and middle one third

Embrasures

• Embrasures are v shaped spaces present interproximally around the proximal contact existing between the adjacent teeth. Types

1.Buccal embrasure 2.Lingual embrasure 3.Incisal/occlusal

embrasure 4.Gingival embrasure

Functions of Embrasures

1)Serve as spillways for the escape of food during mastication

2) Prevent trapping of food in to the contact area

3)Protect the underlying supporting tissue during mastication

Improper contact size

Too broad contact

• It will change the tooth anatomy • It will change the interdental ‘col’ by

broadening it. The delicate non keratinized epithelium may get damaged increasing the chance of periodontal tissue.

• With too broad contact the interdental area is difficult to clean increase the risk of future decay.

Problems associated with faulty

reproduction of contacts in restoration

Too Narrow contact• It will change the tooth

anatomy

• The embrasure size will increase leading to impaction of food vertically and horizontally, thereby damaging periodontal tissue.

Improper contact location

If Contact are placed :

• Too occlusally -It will cause flattening of marginal -

ridges, resulting in too shallow

occlusal embrasure

• Too buccally/lingually- will encroach upon the

respective embrasure

• Too gingivally - will reduce the size of gingival embrasure

and encroach upon interdental gingiva

Open contact

Open contacts would create the problem ready inflow of food causing accumulation of debris , plaque and damage to the periodontal disease

Procedures for developing

correct contact and contour

• To create proper contact and contour with any restorative material, the teeth have to be first separated and then a temporary wall created to support the restorative material in plastic stage.

• Tooth separation to create space between adjoining teeth.

• Matrix application on the prepared proximal side.

RAPID SEPARATION

This is immediate type of separation . This type of tooth movement involves separation of teeth proximally at the point of insertion of separator. The amount of separation produced should not exceed 0.2-0.5mm. Rapid separation can be done by two method

a) Wedge method

b) Traction method

Wedge method of separation

In this method space is created by inserting wedge shaped device between the teeth.

There are two types of separator

1)Wooden / Plastic wedges

2)Elliot separator

Classification of Wedges

1) On the basis of method of fabrication

a) Custom made wedges

b) Pre fabricated wedges

2) On the basis of material used for fabrication

a) Wooden wedges

b) Plastic or synthetic resin wedges

Custom made wedges

• These are made by trimming wood or plastic material in triangular shape to mach that of embrasure. Trimming can be done by scalpel , gold knife or diamond stone.

Wooden wedges

These wedges are made from wood. It may be soft and resilient or hard .they are easy to trim and shape. They absorb water interiorly and swell up ,which causes them to press more press against the matrix there by improving their retention. They are available in two shape.

Triangular shape

Round shape

Triangular Shape Wedges

• These are most commonly used.

• Indicated in cavities with deep gingival margin

• The apex lies below the contact area

• The side of the triangle should be match with mesial and distal embrasure

• Used to depress the rubber dam

• They are preferred in ideal class II cavities preparation as wedging action close to the gingival margin

Round shape wedges

Prefabricated wedges

• They are in triangular in shape and supplied in different size. Their shape should modified by trimming to exactly meet that of the gingival embrasure.

Light transmitting wedges

• These are transparent plastic wedges ,which are available in with built in light reflecting property.

• Indication

Class II composite restoration : These light transmitting wedges help to assist in directing light into inter proximal

areas during initial stages of class II composite curing .

Synthetic Resin/ Plastic Wedges

• They are commonly available different color and size . They have to be trimmed or plastically molded and bent according to the shape of the inter dental col.

Technique of wedge insertion

• Select appropriate wedge, modify its shape according to the shape of the embrasure

• Length of the wedge should half of an inch.

• Grasp the wedges with help of pliers and insert pointed tip from facial or lingual embrasure whichever is larger.

• Wedge should come to lie slightly gingival to the gingival margin of the proximal cavity, pressing the band tightly against the tooth. Once placed it should be firm and stable.

• Test tightness of the wedge with an explorer. the explorer is pressed against the matrix to the margin.

Piggy- Back Wedging

• Useful in cases with gingival recession of inter-proximal tissue . In such cases when the wedge lies in the apical margin of proximal cavity another wedge smaller in size is piggy backed on the first one to fill the space and press the matrix band against the margin.

Double wedging

• This method used in case of wide faciolingual proximal box. In such cases two wedges are inserted, one from facial and other from lingual embrasure.

Wedge Wedging

• Used in maxillary surface of first premolar where a concavity may be present on the proximal surface of the contact and extending to the root as groove . In such case to wedge a matrix band tight against the tooth, a second wedge may inserted between first and band.

Functions of wedges

• They create space between teeth to compensate the thickness of matrix band.

• Immobilize the matrix band.

• Closely press the matrix band against the tooth in the gingival area of the preparation preventing any restorative material escaping below the band.

• Maintaining the health of interdental gingiva by preventing material from impinging.

• Protect the gingiva from unexpected truma.

Elliot separator

• It is also called crab claw separator. It is mainly used for short duration separation such as

1) Examination of proximal surface

2) Final polishing of already restored proximal surface.

Traction Method• It is a method of rapid separation in which the teeth are

mechanically moved apart. The mechanical devices which are used for the purpose are engaged on the proximal surfaces of teeth by means of holding arm and the teeth are clamped. Teeth are physically separated as the nut is turned by the wrench .

Example: Ferrier double bow separator.

Matricing

• Is a procedure by which a temporary wall is created opposite to axial wall that surrounds the area of the tooth structure, which was lost during tooth preparation.

Matrix

• Is a device which used to confine and give shape to the restorative material during its introduction and hardening. the matrix assembly consist of two parts.

Matrix band

Matrix retainer

Matrix band

• It is a false wall in the form of thin piece of metal or other material ,replacing the missing wall in cavity preparation. it may be of different material such as stainless steel ,(toffelemire,ivory bands ),copper(copper bands),celluloid(transparent strips).

• The height of the band should be such that it extend 2mm above the marginal ridge and 1mm below gingival margin of the preparation.

• Matrix retainer : it is an instrument used to hold matrix band in position.

Ideal requirements of Matrix

• It should be simple in design.

• It should be easily applied and readily removed

• It should be rigid enough to withstand condensation pressure preventing the restorative material bulging out.

• It should be able to adapt with the shape and position of different types of tooth. It should be non reactive to the tissue and restorative material.

• It should be inexpensive and readily available.

• It should be easy to sterilize.

Functions of Matrix

• It act as a temporary supporting wall

• It confines the restorative material and allow it to acquire proper shape and form as it harden.

• It retracts the gingiva and rubber dam as the restorative material packed in the cavity.

• It helps to establish the proper contact and contours.

Classification of Matrix Band

A)Depending upon the composition of band material .

i) Stainless steal e.g:Toffelemire.ivory no.1

and no.8

ii) Copper: eg : Copper band

iii) Cellulose acetate : eg:cellophanetransparent strips.

B) Depending upon the method of retention

• i) Using retainers: Toffelemeire ,Ivory no.1and8 bands

• ii) Retainer less band: Copper band ,automatrix

C) Depending upon the preparation

• i) Mechanical matrix e.g:toffelemire retainer ,ivory no.1and8

• ii) Custom made /anatomic matrix e.g compound sectional metal strips.

Toffelemire retainer

• It is a versatile type of matrix retainer. It is also referred to as universal matrix .it was designed by BR Toffelemire .

• Advantages Its main advantage is that it can be placed on the buccal or lingual side of tooth as per requirement It is very stable when in position.

Indication

• It is ideally indicated for MOD cavities

• Class II cavities

• Class I cavities with buccal and lingual extensions

Parts of Toffelemire retainer

• HEAD- This part accommodate the matrix band. It is U shaped with two slots. The open side of the band should be held facing upward when the band is inserted and while positioning the band around the tooth the slot in the head should be directed gingivally. The head maybe straight or angulated with respected to rest of retainer. Accordingly there are two types

Straight toffelemire retainer Contra angled toffelemire

retainer

Locking vice

• This has a diagonal slot. The locking vice is positioned near the head, for the placing the band in the retainer and positioning it around the tooth.

• Pointed spindle

This is used to adjust the distance between the head and locking vice and also adjust the size of matrix band.

Small knurled nut• Turning this nut clockwise tightens the pointed

spindle against the band and thus secure the band in the retainer. The reverse motion release the pointed spindle from locking vise thus releasing the band from the retainer.

Large knurled nut.

• This is used to adjust the size of the loop of the matrix band either to adapt or to loosen from the tooth.

Ivory no.1 matrix

• The matrix consist of a stainless steel band which encircles the proximal surface of posterior tooth. This is attached to the retainer via a wedge shaped projection. An adjusting screw at the end of the retainer adapts the band to the proximal contours of the prepared tooth.

• Indication For restoring U/L ClassII cavity when the contact on the unprepared side is very tight

Ivory No .8

• This matrix consist of a band that encircle the entire crown of the tooth . The circumference of the band can be adjusted by the adjusting screw present in the retainer.

• Indications

For restoring Class II cavities on one or both proximal surface of posterior teeth.

Copper band matrix

• They are cylindrical in shape and can be selected according to the diameter of the tooth to be restored. the band are softened by heating in flame and quenching in water.

• For badly broken down teeth especially those receiving pin amalgam restoration.

• For complex situation like ClassII cavities with large buccal or lingual extension.

• Advantages • Provide excellent contour • Disadvantages • Time consuming

Pre-contoured metal matrix strips with metal rings

This consist of small precontoured soft metal matrices ready for application of the tooth. They are selected according to the tooth to be restored &wedged to adapt to the gingival contour. This metal band held in place by metal ring called BiTine Ring

INDICATION for small class 11 cavities

involving proximal surfaces in posterior tooth.

>for both amalgam & composite restoration.

• Advantages>ease of application.>metal ring also afford slight tooth sepration.>provide better proximal contour for posterior composite restoration than traditional matrices.

Disadvantage>expensive>matrix band become bended easily especially if the contact area of the adjuscent tooth is too close preventing easy insertion of the band.

T –BAND MATRIX

• This is a preformed stainless steel matrix band without retainer

INDICATION

For class 1 cavities involving one or both proximal surface of posteriors

ADVANTAGES

>simple & inexpensive matrix band system

>rapid & easy to apply

AUTOMATRIX

Is a retainer less matrix system designed for any tooth regardless of its circumference and height .

Components1 Auto matrix band:

available in three widths> 3/16th inch>1/4th inch>5/16th inch

2 Automate 11 tightening device- Adjust loop of band according to circumference of the tooth to be

restored.3 Shielded nippers- Used to cut auto lock loop ,so that band can be separated & remove from

the tooth.

Indication> Complex amalgam restoration especially when one or

more cusp are to be replaced.

Advantages> Convenient to be use .> Improved visibility due to lack of interference from a

retainer.> Rapid application.Disadvantage

> Band are flat ,so difficult to burnish> Cannot develop proper proximal contact & contour.

> Expensive

Preformed transparent cervical matrix

These are commercially available in various contour for use in anterior & posterior tooth

INDICATION

For class v restoration with composite resin

For resin modified glass ionomer restoration

ADVANTAGES

Provide good contour for the restoration

DISADVANTAGES

Expensive

Conclusion

It is essential to have adequate knowledge about the anatomical and functional aspects of contacts and contours so as to reproduce them with ideal restorative material which will help o maintain the oral cavity in sound health.