crowns used in pediatric dentistr

CROWNS USED IN PEDIATRIC DENTISTRY

Under the guidance of

Dr Vivek RanaReader

Presented by

Dr Anish Poonia

Dept. of Pedodontics

Contents What is a crown????? Types of crowns stainless steel crown polycarbonate drown celluloid crown metal crown with resin facings artglass crown preformed plastic crowns stainless orthodontic bands acrylic crown anterior jacket crown fabricated acrylic jacket crown

Crown

Crown is an artificial replacement that restores missing tooth structure by surrounding most or all of the remaining structure with a material such as cast metal, resin, porcelain or a combination of materials. It is intended to reproduce both the form and the function of the tooth and to restore the appearance. (Dykema RW , Philips RW –Johnston’s Modern Practice in fixed prosthodontics 1986)

factors influencing the design of crown 1. crown length : Teeth must have adequate occlso

cervical crown length to achieve sufficient retention 2. crown form : Tapered crown interferes with

preparation 3.the size. number and location of carious lesions or

restorations in a tooth affect whether full or partial coverage restorations arc indicated.

4. Periodontal Health Design must he taken into account.

5. Age of the patient : Cast metal or porcelain fused metal crowns usually contraindicated in adolescents.

Preformed metal crowns/ Stainless steel crown 1st described by- Engel 1950, followed by

HumphreyIndications for use—primary molar teeth after pulp therapy (Duggal MS et al,1995, Allen

WE 1966, Fayle SA 1999) for restorations of multisurface caries and for

patients at high caries risk ((Duggal MS et al,1995, Allen WE 1966, Mink JR 1968,)

primary teeth with developmental defects (Goldberg NL 1969, Myers DR 1976,Pinkerton JR 2001)

where an amalgam is likely to fail (Goto G et al 1970, Pinkerton JR 2001)

fractured teeth (Croll TP 1999, Fayle SA 1999) teeth with extensive wear (Fayle SA 1999 ,

Fieldman BS1979) abutment for space maintainer (Brook AH

1982,Fayle SA 1999 , Fieldman BS1979) Rampant caries Severe bruxism

Stainless steel crown

Indications for use—permanent molar teeth interim restoration of a broken-down or

traumatized tooth when financial considerations are a concern,

useful as a medium-term, economical restoration teeth with developmental defects (restoring the

occlusion and reducing sensitivity caused by enamel and dentin dvsplasias in young patients;

Restoration of a permanent partially erupted molar


Objective of using SSC restoration are:

To achieve biologically compatible, masticatorily competent and clinically acceptable restoration.

To maintain the form & function of the tooth


Different types of stainless steel crowns

Untrimmed crowns ( rocky mountain) nor trimmed nor contoured Pretrimmed crown ( unitek stainless steel crown, 3M, denvo

crowns) – straight noncontoured sides, festooned but require contouring.

Precontoured crowns ( unitek SSC, 3M) festooned & contoured


Composition SSC (Austentic alloy- rocky mountain ,

unitek)

17-19% chromium

10-13% nickel

67% iron

4% minor elements

Austentic type- best corrosion resistance


Nickel –base crowns Composition

72% nickel

14% chromium

6-10% Fe

.04% carbon

.35% manganese

.2% silicon

Good formability & ductility

Good wear resistance


Steps Involved in Adaptation of thePreformed Stainless Steel Crown 1. Crown selection 2. Preoperative occlusal evaluation 3. LA administration 4. Rubber dam application 5. Placement of wedges 6. Tooth preparation . Occlusal reduction . Proximal reduction

. Buccal and lingual reduction . Finishing 7. Trial fitting, trimming and contouring the crown 8. Finishing the crown 9. Cementation 10. Post cementation instruction

Crown Selection A correctly selected crown should cover all the

tooth preparation and provide resistance to removal.

festooned crowns - superior - most accurately reproduces the tooth morphology and requires least trimming and contouring.

Primary molar with deep interproximal caries extending sub gingivally - use non-festooned crown to encompass the margins of the preparation.

The factors to be considered during crown selection: a. Mesiodistal width of the tooth: Preoperative MD width

is measured with the callipers and matched with the SSC.

A crown that provides resistance to removal or that requires pressure to place initially -too small

impossible to contour - a grossly over sized crown. Over contoured or oversized crowns on 2nd deciduous

molar can prevent normal eruption of the 1st permanent molars.

The factors to be considered during crown selection………. b. Occlusal anatomy: Deep occlusal fissures

and high cusps - greater reduction of the occlusal surface required.

Such crowns without adequate reduction may not reach the correct gingival level and will rock.

c. Height of the crown: should be same as that of the uncut tooth with cervical margin not more than 1mm below and parallel to the gingival margin

The factors to be considered during crown selection:…………….. d. Primate space: Preoperative assessment

should be done, when 1st deciduous molar is crowned.

Impingement of this space may prevent early mesial shift of the 1st permanent molar.

e. Gingival marginal contour: differs from the 1st to 2nd molar as well from buccal to lingual to proximal aspect.

Three forms of gingival margin contour ‘-Smile', 'Stretched S' and 'frown

Preoperative Occlusal Evaluation A probe when placed on the operating tooth sh

extend and touch the lingual cusps of the two adjacent teeth. This helps in later evaluation of the reduction and crown fit.

Local Anesthesia Administration LA reduces the discomfort to the patient during

tooth reduction and crown manipulation.

Rubber Dam Application prevents slipping of crown into the throat

accidentally and isolation

Placement of Wedges placed in the interproximal space which

acts as tooth separators and also protects the underlying soft tissues.

Tooth Preparation According to Troutman (1976) occlusal

reduction should be done first followed by proximal. But Kennedy suggests proximal reduction should be followed by occlusal reduction

Occlusal Reduction Large round bur, tapered fissure or flame shaped

diamond bur The occlusal reduction of 1.5-2.0 mm follows the

anatomy of the occlusal surface. Initial placement of 1mm depth grooves in the occlusal

surface followed by removal of remaining portion according to cuspal inclines

Sharp line angles should be rounded.

Proximal Reduction The tapered fissure bur moved in bucolingual direction

starting at the occlusal surface 1-2 mm away from the adjacent tooth,

until the contact area clears gingivally and buccolingually.

Buccal and Lingual ReductionMinimal but adequate reduction necessary. The buccal and lingual cervical bulges can be left uncut if they do not interfere in the placement of the crown

FinishingAll the line angles must be rounded.

Figs 13.2A to C: Pliers used for fabrication of stainless steelcrown. A: 417 Crimping pliers, B: 114 Johnson ball and socketplier, used to get a bell shaped contouring, C: 137 Gordon, used for general contouring & shaping


Trial Fitting, Trimming and Contouring The Crown purpose of crown trimming - to leave the crown

margins in the gingival sulcus contouring -to reproduce the tooth's

morphology.

Seating of a crown on a mandibular molar done by first fitting the lingual side and then rotating it buccally.

In the upper arch fit the buccal side first. The position of the gingival margin is

marked subgingivally.

The excess material is cut with curved scissors The crown is then contoured and crimped using

plier resulting in a smooth flowing outline on the margin of the crown.

The crown should snap into place when refitted. Care should be taken to see that there is no gingival blanching and no occlusal interference

Finishing the Crown Final finishing is done with stone and

rubber wheel to remove scratches and obtain shine.

Cementation Cements used are ZnOE, ZnP04, polycarboxylate,

Glass ionomer. Debris –removed The tooth is isolated with cotton. All exposed dentin protected with varnish. The crown is 1/2-2/3 filled with cement mixed to luting

consistency. The crown is seated on the tooth along the pre-determined path of insertion.

The cotton rolls are removed and patient requested to bite gently on the crown to ensure it's being forced to place.

the occlusion is rechecked and excess cement is removed using scaler. from the buccal and lingual aspects and floss can be used for proximal surface.

Postcementation Instruction The patient should be instructed to avoid heavy

chewing with the crown for 24 hours. Instructions for maintaining oral hygiene and

should be recalled once every 6 months

Modifications of Stainless SteelCrowna. When more than one stainless steel crown has to be prepared additional factors to be remembered are i.Occlusal reduction of one tooth should be done completely

before starting the second tooth. If done together there is a tendency to over reduce.

ii. Contact point between adjacent teeth should be broken producing 1.5mmspace at the gingival level.

iii. Both crowns should be trimmed, contoured and prepared for cementation simultaneously.

Cementation of the distal tooth is done first and should be the same as during trial fitting.

b. Drifting of tooth and space loss: The crown required to fit a tilted tooth B-L will be too wide M-D and

crown selected to fit M-D Will be too small B-L. In such a case larger crown is taken and M-D width is adjusted by using Howe plier.

Alternate method when there is space loss is by using the crown of diagonally opposite arch.

c. Undersized crown A vertical cut is made on the buccal surface of the

crown. The margins are pulled apart and an additional piece of

steel band material is spot welded to the buccal surface increasing the dimensions of the crown.

After contouring, the crown is soldered, polished and cemented.

d. Over sized crown : The crown is cut vertically along the buccal wall. The free crown margin are approximated and overlapped over each other spot welded to reduce the crowns dimension. After contouring, the cut and relocated area is soldered and polished.

e. Deep subgingival caries in the interproximal surface

managed by 2 methods a) unfestooned crown b) modified prefestooned crown. A normal prefestooned crown can be used by spot welding

an additional band piece thus increasing the length of the crown wherever required.

f. Open contact (except the primate space): It can be corrected by using larger crown,

Localized addition of solder is also recommended.

g. Anterior teeth: Due to its strength and stability SSC -preferred in grossly destroyed anterior teeth.

Poor esthetics of stainless steel crowns can be improved by removing a portion of the labial surface of the crown or replacing it with a layer of composite resin.

These crowns are also used in the correction of anterior cross bite,

In bruxism: the thickness of the metal on the occlusal surface is increased by addition of a layer of solder from the impression surface of the crown. - Croll's technique.

Complications that mayDevelop during Stainless SteelFabricationa. Formation of interproximal ledge- Leads to inability to

seat the crown.b. Ingestion of crown- overcome by using a square piece

of gauze as throat screen or by using rubber dam. Should this happen PA chest radiograph is mandatory

and patient is referred to the physician. If not found in the radiograph it is assumed to pass

uneventfully through the alimentary tract within 5-10 days

If not found abdominal X-ray is necessary to locate the crown.

c. Failure results from poor and inadequate preparation and improper gingival adaptation.

Not considered to be long term restoration for permanent teeth for they tend to cause periodontal problem.

Cast crown are preferred for children over the age of 15 years. --

Recurrent caries (seldom) occurs around open margins. Children with tooth grinding habit may exhibit wear through

existing SSC. - Lack of accessible tooth surface for future pulp testing. Crown fitting is time consuming and difficult.

Tooth preparation & fit of a SSC


Final placement of SSCStainless steel crown

Open Face (Chair side Veneered) Steel-Crown, Introduced by Helpin(1983).~SSC provides the

strongest and mpst durable restoration for primary anterior teeth.

Advantage

(1) Tooth structure accessible for pulp testing.

(2) Esthetics improved.

Disadvantage It takes long time to place a crown because of two step

procedure. -Crown placement

-Composite placement

Esthetically they are poor, improvement by cutting a window. on labial side, create

mechanical undercuts laterally and incisally and placing composite resin -facing.

The window extends just short of the incisal edge- gingivally, to the. height of 'the gingival crest and MD to the line angles.

Indication for full coronal coverage of incisor 1. Incisors with large interproximal lesions. 2. Incisors that have received pulp therapy. 3. Incisors that have been fractured and have lost an

appreciable amount of tooth structure. Incisors with multiple hypoplastic defects or developmental

disturbances (e.g.ectodermal dysplasia. Discolored incisors that are esthetically unpleasing. Incisors with small interproximal lesions that also

demonstrate large area of cervical decalcification~

There are several methods of providing coronal coverage to primary incisors.

(1) Stainless steel crown (2) Veneered or open face stainless steel crown (3) Resin crown (Strip crown) (4) Polycarbonate crown (5) Preformed plastic crown (6) Stainless orthodontic bands (7) Artglass crowns

Polycarbonate crown Heat molded acrylic resin to restore ant prim teeth

(Stewart R, Luke L, Pike A 1979)-Pediatric dent 2002 Drawbacks- do not resist occlusal fracture or

dislodgement (Nitkin D, Rosenberg H, Yaari A 1977) Pediatric dent 2002

Excess reduction of natural tooth for proper adaptation Rapid detoriation at gingival margin bruxism excessive abrasion of anterior teeth deep impinging overbite

Technique

Crown selection- MD dimension of crown sh be determined

Preparation of tooth- MD surf reduced till contacts are open, surface becomes parallel

labial & Lingual reduced .5mm finish line – Stewart et al prefer Chamfer Myer’s –no finish line

Polycarbonate crown

Incisal edge –reduced 1 -2 mm Add an undercut – increase the retentive

prop of prep Remaining caries –removed Pulp protection Crown adaptation – selected crown

adapted to prep by selective grinding of gingival margin & internal portion of crown

Polycarbonate crown

Cementation of polycarbonate crown

Drill a hole through palatal surface of crown – allows excess resin to escape

Polycarbonate crown

ARTGLASS CROWNS Artglass (Kulzer) – current material for restoring

ant primary teeth It is a crosslinked three dimensional polymer

(Yanover L 1995) Its filler material ( microglass & silica) provide-

greater durability & esthetics than composite strip crowns

Available in 1 shade & 6 sizes for prim central, lateral,& canine teeth

Updyke studied 95 Artglass crowns that he placed in a2-year period.

Of 95 crowns, 79-clinically ideal), 11-clinically acceptable), and 5 clinically unacceptable)

ratings. The vast majority of the failures were due to

bond failures.

Pediatric dentistry 2002

ARTGLASS CROWNS

STRIP (Acid etched ) composite crown / Celluloid Crown introduced by Webber (Braham LR - Text book of

pediatric dentistry 2nd ed) Eg: Unitek pedoderm crown forms 3M Health care crownSelection Criteria 1. When esthetics are a great concern. 2. Adequate tooth structure remain for bonding. 3. Child not highly trauma prone. 4. Gingival hemorrhage is controllable

STRIP CROWN/ CELLULOID CROWN

Indications :

Primary incisors with loss of mesial & distal incisal corners

Nursing bottle caries

Dental hypoplasias

Strip crown technique (Kennedy 4th ed)

Step 1. Isolation desirable, not essential, All caries removed advisable to restore all four incisors at the

same time.

Step 2. the length of the crown is reduced incisorly.

Mesial & distal slices are cut tapering to a knife edge at the gingival margins

If deep overbite - reduce the palatal bulk of the enamel. A calcium hydroxide lining material is applied to the

pulpal wall of any exposed dentine (Fig. 11.3b).Step 3. shade of composite resin is now chosen, usually a

very light shade Step 4. Celluloid strip-crown forms are selected of the right

size and trimmed using fine curved scissors (Fig 11.3c,d).

The crowns are thin and easily split if care is not taken at this stage.

Step 5. Vent holes at the incisal-edge corners of the crown form -allow air to escape when it is filled with composite resin.

crown(s) trial-fitted for length and cervical fit (Fig.

Step 6. The teeth are etched , washed and dried (Fig.

bonding agent applied and cured

Step 7. The crown form is then filled with composite resin, ensuring that resin is squeezed into all its corners.

The resin should be hollowed out in the centre to reduce the amount of excess (Fig. 11.3g).

Step 8. The crown formes) with composite resin are firmly seated on to the prepared teeth (Fig. 11.3h). If more than one incisor is being restored the crowns should be seated together.

Care should be taken to remove excess resin with a probe ()r small Hollenback carver

Excess pressure can result in the crown form splitting so the amount of pressure required is that to seat the crown only

Step 9. composite resin cured for I min, cure thoroughly both labially and palatally.

Step 10. An excavator or probe is inserted beneath the edge of the celluloid and the crown formes stripped off (Fig.).

Reduction of the incisal length may be neededFinal Step. The cured crown is smoothed and

polished, The finished crown(s) restore the aesthetics

ADVANTAGE: Strip crown technique is quick & simple method for restoration of primary incisors

encourages an interest in dental health for both parents and child.

Very good esthetic.

Drawbacks: Strip crown are difficult to place because of the

complexities of tooth preparation, pulp protection, moisture control (especially that

of marginal bleeding when caries is subgingival) the need for a perfect bonding technique.

resin composite placement

Pediatric dentistry 2002 Celluloid Crown

Preformed plastic crowns serve as the best esthetic replacements of

gross caries affecting primary anteriors. enamel of the incisor is cut away with a

tapered fissure bur. preformed plastic crown is fitted cemented to place with a zinc phosphate

cement.

Stainless Orthodontic Bands used to restore badly decayed anterior teeth. Remove all caries from the teeth and apply a Ca(OH) sub

base if necessary. Fit the commercially available stainless orthodontic bands to

each tooth. Trim away the labial portion of the band so only a narrow

portion (1 ½ to 2 mm) of the band remains gingivally. Cement the band in place. Use the brush technique to apply restorative acrylic, result is esthetically pleasing for the patient and child and

economically feasible

Metal crowns with resin facings/ preveneered SSC a new type of crown form for anterior primary

teeth Its aim is to combine the ease of fit and strength

of the preformed SSC with the aesthetics of the strip crown.

These crowns, marketed as Kinder Crowns (Mayclin Studio Inc., Minneapolis, MN), may be used in place of the strip crown, but they are much more expensIve.

reduce incisor teeth for resin faced crowns to provide sufficient space for the steel crown,

remove the caries, and leave sufficient tooth for retention of the crown.

Mesial and distal slices - to clear the interproximal contacts. The gingival margin should have no ledge or Incisal reduction -to prevent unnecessary elongation of the tooth.

Tooth reduction should not destroy undercuts for mechanical retention;

Lingual reduction - necessary when the overbite is complete,

If incomplete overbite or open bite exists- no indications of closing, the lingual surface need not be reduced;

tooth reduction on labial surface -to remove caries

A pulp-protecting base placed Crown selection and contouring same as for

posterior crowns. Finished crowns provide an aesthetic

restoration with the strength of metal crown.

Acrylic Jacket CrownTechnique: Reduce incisal edge by 2-3 mm. Slice mesial and distal surfaces - walls of the preparation

converge from the cervical margin to the. incisal edge. no shoulder at the cervical margin. Reduce labial and palatal surfaces. Remove only enough labial enamel to eliminate the natural

contouring of the labial surface. palatal reduction depends on the occlusion. Smooth the preparation. Take an impression with a silicon type impression material. Make a temporary crown.

The Patient's Next Visit: Before cementing the laboratory made acrylic crown select the proper shade of cement by mixing cement powder with water and placing it in the crown

For a child a minimal shoulderderless tooth preparation recommended to avoid damaging the pulp.

Acrylic Jacket Crown

Fabricated Acrylic Jacket Crown Sherman and coworke~ have described an acrylic

jacket crown for fractured primary incisor which can be fabricated in one appointment.

Acrylic jacket crown is contraindicated in following situation:

(I) Insufficient tooth structure to ensure adequate retention.

(2) Patient with a deep overbite and small overjet (3) bruxism

Procedure A celluloid crown form of the same MD width - trimmed

approx I to 2 mm longer than the normal clinical length of the crown.

incisal edge of the tooth - reduced by approximately I mm.

A shoulder is extended below the free gingival margin on the labial, mesial and distal surfaces, but only 0.5 mm on the lingual.

The M and D surfaces should be nearly parallel prepared tooth lubricated with petroleum jelly- crown form is filled with the appropriate shade of acrylic.

The crown form is held for about 1 minute until the surface "frosts" and then it is seated firmly on the lubricated tooth

Fabricated Acrylic Jacket Crown

crown is held stationary for 2 to 3min with firm finger pressure and then carefully removed from the tooth.

crown is placed in a glass of warm water for 10 to 1 5 minutes.

When removed the acrylic will be hard, all margin should be trimmed back,

After proper gingival margin have been established the celluloid crown form is removed using a scalpel blade and the margins are carefully buffed with the fine pumice

The acrylic crown is cemented into place using the appropriate shade of ZnP04 cement

Fabricated Acrylic Jacket Crown

Factors to be considered Correctly selected crown – sh cover all tooth prep

& provide resistance to removal Preop M-D width of tooth sh be measured &

matched with an approp SSC Consider the presence or absence of primate

spaces for 1st prim molar- impingement upon primate space by

oversized crown may prevent mesial migration of mand 1st perm molar from cusp to cusp occ into angle cl I relationship.


Overcontoured and oversized crowns –on II prim molar- prevent normal eruption of 1st perm molar


Tooth Preparation

1. Clean tooth with prophylaxis paste. 2. Check the shade of the restoration required. 3. Reduce tooth surfaces and incisal length to

allow crown form to fit over tooth. Consider preparing a circumferential retention

groove in cervical third 4. Remove remaining caries 5. Maintain a dry field 6. Protect pulp with appropriate material.

Celluloid Crown

Crown Preparation Select appropriate crown and trim margins

with scissors. 2. Try the crown over the tooth to check

contour and margins. make a small hole in the palatal side

(excess material to flow out)

Celluloid Crown

Procedure Etch the enamel with etching solution or gel (40%phosphoric

acid -15 to 30 sec.) wash the tooth for 30 see with the water dry it with the air syringe check for chalky white enamel Apply adhesive Fill the crown form with restorative material, avoiding air bubbles. Place the filled crown in the prepared tooth. Quickly remove any excess material with a probe.

(Interproximal areas)

Celluloid Crown

When the material has hardened cut through the crown form with a probe starting at the cervical margin and strip it off leaving a smooth surface.

Check the cervical margins and the occlusion carefully and make any necessary adjustment before dismissing the patient.

Celluloid Crown

Pre-veneered Stainless Steel Crowns New preveneered SSC for primary incisors and

canine are now available (e.g. Kinder Krowns. Whiter Bite -crowns, Nu smile primary crown):-

Preparation identical to the preparation for open face crown.

The advantages -short operating time and the durability of the steel crown is maintained.

less sensitive to moisture Disadvantage - crimping is limited to the lingual

surface

Prefabricated metal crowns Div into – permanent & temp crowns for

primary teeth (Braham LR Restorative dentistry .text book of pediatric dentistry)

Permanent – stainless steel or nickel base alloy

Temporary- aluminium or tin base alloy

The factors to be considered during crown selection:…………. "Smile": The outline of the buccal gingiva of the second

deciduous molar and the lingual gingiva of both the deciduous molars resemble a smile.

"Stretched S": Owing to the mesiobuccal cervical bulge, the gingival margin dips down in the buccal aspect of 1st deciduous molar as it continues from distal to mesial giving the configuration of a'S' that has been stretched on one side.

"Frown": Due to short occlusocervical height at the mid point on the proximal aspect the gingiva dips down on either side of this midpoint giving a frown line.

crowns used in pediatric dentistr

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