Contacts & Contours

Dr. Nithin Mathew – Contacts & Contours

Contents

• Introduction• Contacts• Contours• Proximal Contact Area• Embrasures• Marginal Ridges

• Procedures for formulation of proper contacts and contours:

• Tooth movement• Rapid• Slow

3


• Matricing• Classification• Types

• Recent Advances• Conclusion• References

4

Dr. Nithin Mathew – Contacts & Contours5

• Presence of proper contacts & contour is important to maintain stability &occlusal harmony.

• A thorough knowledge of the contacts & contours of various teeth ismandatory for understanding:

• Predisposing factors of proximal caries like faulty interrelationships.

• Significance of marginal ridges, embrasures for re-establishing theform and function of restored teeth.

• Periodontal aspect & health of the tooth to be restored.


• Benefits of an ideal contact & contour:

1. Conserves the health of peridontium

2. Prevents food impaction

3. Makes area self cleansable

4. Improves longevity of proximal restorations

5. Maintains normal mesiodistal relationship of the teeth in the dental

arch


• Role of a dentist is to establish the ideal extension so as to performoptimal functions, maintaining the integrity and longevity of individualtooth.


Food we consume moves in 3 different directions:

• Occlusal surfaces

• Contact & Gingival embrasures

• Facial & Lingual sulcus


• Any decay occurring on the proximal surface is mainly due to faultyinterrelationship between

• Contact Areas

• Marginal Ridges

• Embrasures

• Gingiva.


• Time of eruption: only contact point

• Proximal Contact Point Proximal Contact Area


Proximal Contact Area

11

• Area of proximal height of contour of the mesial or distal surface of atooth that touches the adjacent tooth in the same arch.

• According to their general shape, 3 types:

1. Tapering teeth : Wide crowns & narrow cervical region2. Square type : Bulky, angular with little rounded contour3. Ovoid type : A transitional type between tapering & square types

: Surfaces are convex but infrequently they may be concave

12

CONTACT TAPERING SQUARE OVOID

BetweenIncisors

Contacts starts at incisalridge & labial, labiolingually

Starts at incisal ridge & inclinewith it labiolingually

Slightly lingual to incisal ridge

Mesial contact start at 1/4th ofcrown incisogingivally

Distal contact start 1/3rd to ½of crown incisogingivally

Canine Mesial: incisal ridgeDistal: middle thirdVery angular

Close to incisal ridge incisally Close to incisal ridge incisally

Bicuspids Buccal periphery is almost atbucco-axial angle

Buccal periphery more towardsbucco-axial angle

Buccal periphery at junctionof buccal & middle third

Occlusal periphery atjunction of occlusal & middle3rd of crown

Occlusal periphery at occlusalthird

Contact deviated buccally Short cusps

13

CONTACT TAPERING SQUARE OVOID

Molars(mesial contact)

Buccal periphery almost at bucco-axial angle of tooth

Same as premolars Same as premolars

Occlusal periphery at junction of occlusal & middle third of crownLarge cusps

Molars(distal contact)

Buccal periphery at middle third

More lingually deviated thanmesial

Buccal periphery in line with central groove

Embrassures Wide variationsIncisal & labial are negligible

Incisal, lingual, occlusal & buccalembrasures are NIL

Incisal, labial, buccal & occlusal embrasures are wider & deeper

Gingival & lingual embrasures between anterior teeth are the widest & longest in the mouth

Gingival embrasures are almost not noticeable

Gingival & lingual are short & broad

- Buccal embrasures are small, lingual are long


Contours

14

• Convexities on the facial & lingual surfaces of tooth that affordsprotection & stimulation of the supporting tissues during mastication.

Functions of contour:

1. Deflecting food2. Maintenance of periodontal tissues3. Maintain contact with adjacent tooth


Height of Contour

15

• Area of greatest circumference on the facial and lingual surface of theteeth.

• Protects the gingival tissue by preventing food impaction.

ANTERIOR POSTERIOR

Cervical 3rd on facial & lingual surface

Gingival 3rd on facial surfaceMiddle 3rd on lingual surface


Types of contour

16

OVERCONTOUR

• Deflects food away from gingiva• Understimulation of supporting tissues• Plaque accumulation

UNDERCONTOUR

• Irritation to soft tissues

ADEQUATE CONTOUR

• Stimulation of supporting tissues• Healthy peridontium


Embrasures (spillways)

17

• V-shaped spaces between the teeth thatoriginate at the proximal contact areasbetween adjacent teeth.

• Curvature formed by two adjacent teeth in anarch form a spillway space that is called anembrasure.

• Serves 2 purposes:• Provides a spillway for passage for food during mastication• Prevents food from being forced into the contact area

18

• Named for the direction towards which they radicate:facial, lingual, incisal/occlusal, gingival

Lingual/Palatal

Facial/BuccalIncisal/Occlusal

Gingival


• Gingival embrasures filled with papilla – prevents food being trapped inthis region

• Anterior : papilla is triangular• Posterior : tent shaped (col)

• Correct relationship of embrasures, cusps, sulci, marginal ridges & groovesof adjacent and opposing tooth provide escape of food from the occlusalsurface during mastication


• Embrassure is reduced: additional stress is created in teeth & supportingstructures.

• Embrassures is large: less protection to supporting structures

• Lingual embrasure is greater than buccal, since tongue can displace foodocclusally.


Marginal Ridges

21

• Rounded borders of enamel that forms the mesial &distal margins of occlusal surfaces of molars &premolars and the mesial and distal margins oflingual surfaces of incisors and canine.

• Always formed in 2 planes: buccolingually meetingat a very obtuse angle

• This feature is essential when an opposing functional cusp occludes withthe marginal ridge.


• Functions:• Helps in prevention of food impaction proximally• Mastication• Protection of peridontium

• Marginal ridges of adjacent posterior teeth should be at the same height tohave a proper contact and embrasure forms.

23

• Marginal ridges with normal occlusal


• Marginal ridges with exaggerated occlusal embrasures causes drifting oftooth which leads to wedging of food


• Adjacent marginal ridges are not compatible in height - drives the debrisinterproximally.


• Marginal ridges with no triangular fossa, the vertical forces will impactfood interproximally.


• Thin marginal ridges will be susceptible to fracture or deformation


• Marginal ridges with no occlusal embrasures, the 2 adjacent marginalridges will act like a pair of tweezers grasping the food substance passingover it.


Procedures of proper contacts & contours

29

• Intraoral procedures:

• Tooth movement• Matricing


Tooth movement

30

• Act of separating the involved teeth from each other, bringing themcloser to each other or changing their spatial position in one or moredimensions.


Objectives:

• To bring drifted, tilted or rotated teeth to their indicatedphysiological positions

• To close space between teeth not amenable to closure byrestoration

• To move teeth to another location

• To move the teeth occlusally or apically to make them restorable.

• To move teeth from a non-functional or traumatically functionallocation to a physiologically functional one.


• To move teeth to a position so that when restored, they will be in amost esthetically pleasing situation.

• To move teeth in a direction and to a location to increase thedimensions of available structure for resistance and retention form.

• To create sufficient space for thickness of matrix band.


Tooth Movement

Rapid / Immediate Slow / Delayed


Rapid/ Immediate movement

34

• Mechanical type of separation

• Creates either proximal separation at the point of separator’s introductionand/or improved closeness of proximal surface of opposite side.

Indications:• As preparatory to slow movement• To maintain the space gained by slow movement

• Separation shouldn’t exceed the thickness of the involved tooth’speriodontal ligament thickness. ie: 0.2 – 0.5 mm


Methods

35

1. Wedge method

• By insertion of a pointed wedge shaped device between the teeth

• The more the wedge moves facially or lingualy, greater is the separation.


Elliots separator

• Indicated for short duration separation that does not necessitatestabilization

• Useful in examining proximal surfaces in final polishing of restoredcontacts.


Wood/ Plastic Wedges

• Used in both tooth separation for preparation and restoration

• Triangular shaped wedges (wood/synthetic resin)

• Cross-section base of triangle will be in contactwith interdental papillae.

• Two sides of the triangle should coincide withthe corresponding 2 sides of the gingivalembrasure.

• Apex must coincide with the gingival start of thecontact area.


Functions:

• Hold the matrix band in position

• Slight separation of the tooth

• Provides space for placing matrix band

• Prevent gingival overhang

• Stabilizes matrix and retainer

• Assure close adaptability of matrix band to the tooth

• Protect interproximal gingiva from unexpected trauma


• Types:• Wooden• Plastic• Elastic• Transparent• Medicated wedges

• Shape:• Triangular• Round• Trapezoidal


Wedging method:

• Location : Gingival embrasure just beneath the contact area.

• Selection : Depending upon the clinical situation.: Wooden wedges can be trimmed using a knife or scalpel blade

to produce a custom fit.

• Placement : From the lingual embrasure which is normally larger in size.: But if it interferes with the tongue it may be placed from the

buccal side.

• Length : ½” or 1.3cm so that it does not irritate the tongue or thecheek.

• After placement the wedge should be firm and stable.


Wedging techniques

1. Single wedge technique

• Single wedge is placed in the gingivalembrasure

2. Piggyback wedging

• A second wedge is placed on top of the firstwedge to wedge adequately the matrix againstthe margin

• Indicated for patients whose interproximaltissue level has receded.


3. Double wedging technique

• Here, 2 wedges, one from the facial embrasure and the other from thelingual embrasure are used.

• Used when proximal box is wide faciolingually.

• Should be used only if the middle 2/3rd of theproximal margins can be adequately wedged.


4. Wedge wedging technique

• Used in cases when there is a gingival concavity as in the case of afluted root.

• Inorder to wedge a matrix band tightly against such a margin, a secondwedge is inserted between the first wedge and the band.


• Rounded toothpick wedge is usually the wedge of choice with conservativepremolar boxes.

• Triangular wooden wedges are more recommended since:

• Easy to trim and adapt well to tooth surface

• When properly shaped, they remain stable during condensation

• Absorb moisture and swell to provide adequate stabilisation

• Wooden wedges can be cut from toothpicks


Light Transmitting Wedges

• Plastic wedges which are transparent and have a light reflecting core.

• Used with transparent matrices

• Can transmit 90 – 95% of the incident light : drawing the curing light tothe gingival margins of the restoration

• Provides better marginal adaptation at the cervical area of the class IIcomposite resin restorations


Prewedging

• The procedure of inserting a wedge between the interproximal surfaces oftwo adjacent teeth prior to cutting a cavity involving a proximal wall.

Purpose is to achieve some tooth separation such that, after restoration, theteeth will return to their original position and a more positive tooth contactarea will be achieved.


Error’s with wedge placement

• If wedge is placed more occlusal to the gingivalmargin, creates abnormal concavity in the proximalsurface of the restoration.

• If wedge is for apical to gingival margin, band will notbe held tightly against the gingival margin & createsgingival overhangs in the restorations.

• Tightness of the wedge is tested by pressing the tip of an explorer firmlyseveral points along the middle 2/3rd of the gingival margin against thematrix band.


2. Traction method

• Done with mechanical devices which engage the proximal surfaces of theteeth to be separated by means of holding arms.

• Non-Interfering true separator• Ferrier double-bow separator


Non-Interfering true separator

• Indicated when continuous stabilized separation is required.

• Advantage:• Separation can be increased or decreased after stabilization• Device is non-interfering


Procedure:• Apply the jaws closest to the bow against the tooth to be operated

upon.

• Apply a piece of softened compound to teeth under separator.

• A wrench used to move the jaws over the approximating tooth.

• The Nut on the facial side moved first until the jaw touches thesurface needed, then that of lingual side.

• Repeat the adjustment until desired amount obtained.


Ferrier double-bow separator

• Separation is stabilized throughout the dental operation.

• Advantage :• Separation is shared by the contacting teeth and not at the

expense of one tooth


Procedure:• Four arms are adjusted so each will hold a corner of proximal

surface of contacting teeth.

• Arms will be gingival to contact area.

• Wrench applied to labial and lingual to make desired separation.


Slow/ Delayed tooth movement

53

Indications:

• When teeth have drifted and/or tilted considerably, rapid movement ofthe teeth to proper position will endanger the periodontal ligaments.

• Therefore slow tooth movement over weeks will allow properrepositioning of teeth in physiological manner.

Methods:• Separating wires• Oversized temporaries• Orthodontic appliances


Separating wires

• Thin pieces of wire are introduced into the gingival contact area

• It is then wrapped around the contact area.

• The 2 ends are then twisted together to create separation not to exceed0.5mm

• Wires are tightened periodically to increase the separation.


Oversized temporaries

• Resin temporaries are oversized mesio-distally to achieve slowseparation

• Resin added periodically to increase the amount of separation not toexceed 0.5mm


Orthodontic appliances

• Fixed appliances – most effective and predictable method

• Removable appliances can also be used – requires longer treatment


Matricing

57

Procedure where a temporary wall is created opposite to the axialwalls, surrounding areas of tooth structure that were lost duringpreparation.


Matricing

58

The matrix should:

• Displace the gingiva and rubber dam away from the cavity margins

• Assure dryness and non-contamination of the cavity

• Provide shape for the restoration during setting of the restorativematerial

• Maintain its shape during hardening of the material

• Confine the restorative material within the cavity


Matrix

Matrix is a device that is applied to a prepared tooth before theinsertion of the restorative material to assist in the development of theappropriate axial tooth contours and inorder to confine the restorativematerial excess.

Primary function of a matrix is to restore the anatomic contours andcontact areas.


Parts of a Matrix system involves:• Band • Retainer

Matrix Band

• Supplied as strips of various dimensions

• Thickness of 0.001” or 0.002”

• Width may be ¼”, 3/8”, 5/16” or 1/8”

• Depending on the height of the proximal surface, suitable size isselected.


Retainer

• Device by which a band can be maintained in its designated positionand shape.

• Can be a mechanical device, dental floss, a metal ring or an impressioncompound.


Qualities of a good matrix includes:

1. Rigidity

2. Establishment of proper contour

3. Prevention of gingival excess

4. Convenient application

5. Ease of removal

6. Inexpensive


Classification of matrices:

1. Based on mode of retention:i. With retainer (Tofflemire matrix)ii. Without retainer (Automatrix)

2. Based on type of bandi. Metallic non transparentii. Nonmetallic transparent

3. Based on type of cavity for which it is usedi. Class I cavity

a. Double banded Tofflemire (barton’s matrix)


ii. Class II cavitya. Single banded Tofflemireb. Ivory matrix No. 1c. Ivory matrix No. 8d. Copper band matrixe. Automatrix

iii. Class III cavitya. Mylar stripb. S-shaped

iv. Class IV cavitya. Mylar stripb. Transparent crown form

matrixc. Modified S-shaped

v. Class Va. Window matrixb. Cervical matrix


Universal Matrix (Tofflemire matrix)

• Designed by BR. Tofflemire

• Ideally indicated for 3 surface posterior tooth

• Commonly used for class II restorations

• 2 types:• Straight• Contra-angled


Parts of a Retainer:


Advantages:

• Can be placed facially/lingually

• Retainer and band are stable when in place

• Retainer is separated easily from the band

• Retainer helps to hold the cotton roll (for isolation) in place


Matrix bands:

1. Uncontoured bands• Available in 2 thickness : 0.002” and 0.0015”

• Burnishing the thinner band to contour is more difficult and lesslikely to retain contours

2. Precontoured bands• Needs little or no adjustment• Expensive• Difference in cost justified by lesser chair time.


Clinical Technique:

Shaping the Matrix

• Matrix band - shaped to achieve proper contour and contact

• Band is burnished before assemblingmatrix system

• No. 26 – 28 burnisher - recommended

• Band is placed on a resilient paper(contouring cannot occur on hard surfaces)


• Small round burnisher used with firmpressure in back-forth motion until the bandis deformed occlusogingivally.

• After the band is deformed, larger egg shapedend is used to smoothen the burnished band.


Preparing the retainer to receive the band

1. Larger knurled nut is turned counterclockwiseuntil the locking vise is 6mm from the end ofretainer.

2. Holding the larger nut, smaller nut is turnedcounterclockwise until the pointed spindle isfree of the slot in the locking vise.


3. Matrix band is folded end to end forming aloop.

4. Band is positioned in the retainer so thatthe slotted side of the retainer is directedgingivally.The band is placed through theappropriate guide channel depending onthe location of the tooth.


5. Two ends of band are placed in the lockingvise, smaller nut is turned clockwise totighten the pointed spindle against the band.

Placing the band with retainer on prepared tooth

1. Matrix band is fitted around the tooth ( 1mm apical to the gingivalmargin)

2. Larger knurled nut is rotated clockwise to tighten the band slightly.After checking gingival margins and band positioned correctly, band issecurely tightened.

3. All aspects are checked and wedges are placed.


Removal of the band with retainer

1. Retainer is removed from the band. Matrix is removed only afterensuring hardening of the amalgam.

2. Index finger is placed on occlusal surface to stabilize the band as retaineris removed.

3. No.110 pliers are used to tease the band freefrom one contact point at a time.A straight occlusal direction should be avoidedduring matrix removal to prevent breaking of themarginal ridges.

4. Wedge is left in place to provide separation of teeth while matrix band isremoved. After that it is removed.


Clinical Application:

• Damaging gingival attachment should be avoided

• One deeper proximal margin – band is modified (prevent damage togingiva or attachment on shallow side)

• Band may be trimmed for shallow gingival margin

• Positioned 1mm apical to gingival margin or deep enough to be engagedby the wedge and 1-2mm above the adjacent marginal ridge.


Ivory Matrix No.1

• Band encircles the posterior proximal surfaces so it is indicated inunilateral class II cavities.

• Band is attached to the retainer via a wedge shaped projection.

• Adjusting screw at the end of the retainer adapts theband to the proximal contour of the prepared tooth.

• As adjusting screw is rotated clockwise, the wedgeshaped projections engage tooth at the embrasures of theunprepared proximal surface.


Ivory Matrix No. 8

• Consists of band that encircles the entire crown of thetooth.

• Indicated for bilateral class II cavities.

• Circumference of the band can be adjusted by adjustingthe screw present in the retainer.


Black’s matrices

1. For simple cases recommended for majority of small & medium sizecavities

• Metallic band is cut so that it will extend only slightly over buccal &lingual extensions of cavity

• Held in place by a wire or a dental floss.


2. Blacks matrix with gingival extension

• To cover gingival margin of a subgingival cavity

• Corners are rounded to prevent wounding the soft tissues.

• Held in place by a wire or a dental floss


Copper Band Matrix / Soldered Band

• Indicated for badly broken down teeth such as those receiving pinretained amalgam restorations & in complex class II restorations withbuccal or lingual extensions

• Cylindrical in shape

• Band with appropriate dimensions of crown are taken and the 2 ends aresoldered.


• With curved scissors, the band is festooned in the cervical region to fit thegingival contour of the tooth.

• Then with the contouring pliers, the band is contoured to reproduce theproper shape of the contact areas.


Anatomical Matrix

• Most efficient means of reproducing contacts & contours

• Hand-made and contoured especially for individual teeth.

Procedure:

• Stainless steel band (0.001” – 0.002” in thickness) and 1/8 “ in width isdrawn between the handle of a pair of festooning scissors.

• Band is cut to appropriate length.


• Must extend beyond the cavity margins

• Wedge is placed.

• Small cones of compound material are warmed and thenforced into the buccal and lingual embrasures.

• Pressure is maintained until compound has evenlyflowed into the buccal and lingual surfaces of adjacentteeth

• Staple is heated and forced into the compound in thebuccal and lingual embrasures.

• Restoration is then placed


Roll in band matrix ( Automatrix)

• Retainerless matrix system with 4 types of bands that are designed to fit allteeth regardless of circumference and height.

• Types:• 3/16” (4.8mm), 0.002” thickness• 1/4” (6.35mm), 0.002” & 0.0015” thickness• 5/16” (7.79mm), 0.002” thickness


• Advantages:

• Convenience• Improved visibility because of absence of retainer• Ability to place the autolock loop on facial/lingual surface

• Disadvantages:• Band is flat, difficult to burnish• Sometimes unstable even with the use of wedges• Development of proximal contour is difficult.


S-shaped Matrix Band

• For class III, class II and with facial/lingual extensions ofclass V

• Matrix band of 0.001” – 0.002” is used

• Mirror handle is used to produce the S-shape in the strip

• Strip is contoured in its middle part with contouring pliersto create desired form for the restoration

• Compound material is used to hold the band in position inthe facial and lingual aspect and also in the gingival aspect.


T-shaped matrix

• Premade T-shaped brass/ stainless steel matrixbands

• Longer arms of the matrix is bent to encompass thetooth circumferentially and to overlap the shorthorizontal arm of ‘T’

• This section is then bent over the long arm, loosely holding it in place.

• Wedges can be used to stabilize the matrix.


Indications:• Class II cavities involving 1 or both proximal surfaces of a posterior

tooth

Advantages:• Simple• Inexpensive• Rapid• Easy to apply

Disadvantages:• Flimsy in structure and not stable


Mylar Strips

• For composite restorations in Class III and Class IV cavities.

Procedure

• Mylar strip is burnished with the end of aninstrument handle to produce a belly.

• This produces a normal contour of theproximal surface of the teeth.


• Strip is then cut to place the belly where thecontact is desired.

• A wedge is trimmed and applied to hold thestrip in place.


• Lingual aspect of strip is secured with indexfinger

• Facial portion is reflected away for access.

• Following insertion of composite, matrixstrip is closed and material is cured throughstrip.


Aluminium Foil Incisal Corner Matrix

• Stock metallic matrices shaped according to proximo-incisal corner andsurfaces of anterior teeth.

• Cannot be used for light cured resin materials.


Procedure:

• A corner matrix closest in size and shape of teeth is selected.

• Trimmed gingivally to coincide with gingival architecture and coversgingival margin of preparation.

• It is shaped with fingers until it fits mesio-distal and labio-lingualdimensions of tooth.

• Wedge is placed

• Apply the restorative material

• Tighten the wedge and wipe off excess material.


Transparent Crown Form Matrix

• Stock plastic crowns• Can be used for light cured resin material• For Class III and Class IV

Procedure:• Appropriate size is selected that matches closely with the inciso-

gingival dimension of the tooth to be restored.

• Trim the crown gingivally to match with the gingival architecture.


• Should be perforated at the incisal angle.

• The prepared tooth is partially filled with therestorative material while the matrix is completelyfilled.

• Placed over the prepared tooth surface.

• Wedge is tightened

• Excess material is wiped off, held under the fingerpressure.


• Indications:• Large bilateral/unilateral class IV cavity• Oblique fractures of anterior teeth

• Advantages:• Easy to use• Good contours can be established

• Disadvantages:• Time consuming• Expensive


Window Matrix

• For class V cavities• Formed using either a Tofflemire matrix or copper band.

Procedure:

• A window is cut slightly smaller than theoutline of the cavity.

• Wedges are placed, mesially & distally tostabilize the band.


Preformed Transparent Cervical Matrix

• For use with light cured resin material or RMGIC• Matrix must be held in place while the restoration

is setting

• Indications:• Class V restorations with composite or RMGIC

• Advantages:• Provides good contour for restorations

• Disadvantages:• Expensive


Contact Forming Instruments

100

• These are special instruments designed to create good contacts withposterior composites.

• They push the matrix toward the contact area during light curing.

Eg:• Contact Pro• Optra contact


Contact Rings

101

• Work by providing slight separation of the contacting teeth.

• Spring action applies equal and opposite forces against the teeth thusproviding optimum separation.

• After separation, the composite is incrementally built and cured in a passivemanner.

• Finally, the ring is removed andthe teeth are brought back into contact.


• According to their evolution, categorized as• First generation systems• Second-generation systems

First generation systems

• Introduced in the late 1990sInclude :-

• Palodent Bitine• Contact matrix• Composi-Tight

Palodent Bitine

Composi-Tight


Palodent BiTine I and BiTine II

• First system that was available.• Rings have rectangular tines which are

parallel.• Provide optimum separation (0.55 kg/mm).• Lack retentive design because of the parallel

tines but are easy to place on widepreparations.

• BiTine II is an elongated ring to allowstacking over the main ring in case of MODpreparations.


Contact matrix

• These rings have rectangular tines which are converging and henceare more retentive.

• Provide optimum separation (0.38 kg/mm).

• A reverse ring is available for MOD preparations.


Composi-Tight matrix

• Two separate rings are available for premolar and molar teeth.

• The rings have converging tines with retentive balls at the end forfirmer grip on the teeth.

• Omnidirectional.

Drawback:• Contacts produced are not so tight (0.27 kg/mm).

• Large diameter of the rings can lead to their collapse if used in widecavities.


Precontoured sectional matrix bands

• All these systems rely on precontoured sectional dead soft metalmatrices

• Available in various shapes, thicknesses and sizes.


Benefits with the Sectional Matrices and Contact Rings

• Ease of use and good visibility.

• Anatomic contour of the bands ensures optimal contact areas andembrasures.

• Less tension on the teeth and greater comfort for the patient

• No need for pre-wedging.

• Contact dimensions are adequate and in the correct anatomic location.

• Gingival adaptation of the restoration is good.


Problems with early contact rings

• Ring collapse or displacement in case of wide proximal boxes.

• Ring stacking that is, placing one ring over the other in case of MODrestoration is a problem.

• Most importantly, since the contact rings are made of stainless steel,repeated usage and sterilization effects make them lose theirspringiness over time.


Second - Generation Rings

Eg:-

• Composi-Tight 3D soft face ring system

• V3 ring system.


Composi-tight 3D Soft Face Ring System

The orange Soft Face 3D-Ring• Used in most circumstances• Ease of placement• Ability to adapt to a wide variety of tooth

anatomies while reducing flash and restoringproper contour.

The gray thin tine G-Ring• Burnished tine ends• Used where the shape of the dentition makes ring

retention more problematic


V3 Ring System

• Developed by Dr. Simon McDonald in 2008

• System has two types of rings for bicuspid and molar teeth

• Precontoured matrix bands

• Special wedge called the ''wave wedge'' to provide optimum gingivaladaptation of the matrix band.


It has two major innovations

• Fully made of Nickel-Titanium ;imparts more springiness and longevitythan stainless steel.

• V-shaped plastic tines to accommodate the wedge.

• The tines have extra width that enables the ring to contact more toothstructure buccally and lingually.


Fender Wedges

113

• For protection and separation during toothpreparation.

• Combination of a steel plate and a plastic wedge.

• Inserted into the inter dental space it provides aprotector for the tissue and separates the teeth,simplifying the following application of a matrix.

• Can be applied buccally or lingually for optimal accessand vision.


• Available in four color coded sizes

• Should be inserted with firm pressure providing a tight stable fitthroughout preparation.


Conclusion

115

• Proper restoration of the anatomical landmarks is important forenhancing the longevity of restorations as well as to maintain the occlusalhealth and harmony.

• Matricing is a vital step during the placement of different restorations.• Selection of the matrix should be based on its ease of use and efficiency to

provide the optimum contacts and contours..

• The dentist should select the right method according to the needs ofindividual case.


References

116

1. Operative Dentistry – MA Marzouk

2. Art & science of operative Dentistry – Sturdevants (5th edition)

3. Art & Science of Operative Dentistry – Sturdevants (South Asian Edition)

4. Textbook Of Operative Dentistry – Vimal K Sikri (1st Edition)

5. Dental Anatomy, Physiology & Occlusion – Wheeler’s (9th Edition)

6. Optimizing tooth form with direct posterior composite restorationsJCD Oct-Dec 2011 | Vol 14 | Issue 4

Contacts & Contours

Education

Transcript of Contacts & Contours