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8/7/2019 Journal Club1

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Journal ClubPresented by

Dr. Manjeeev GuragainPG Resident

Department of prosthodontics and maxillofacialprosthesis

Peoples Dental college and Hospital

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The effect of post, core, crown type,and ferrule presence on the

biomechanical behavior of

endodontically treated bovine

anterior teeth.Natrcia Rezende da Silva et al

(J Prosthet Dent 2010;104:306-317)

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Introduction Endodontically treated teeth undergo changes in

mechanical properties

fracture strength

(loss of tooth structure degradation in structural

integrity)

modulus of elasticity

proportional limit

strength and brittleness 3


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Options

Definitive restorations

metal ceramic crowns

alumina-reinforced ceramic crowns

Remaining tooth structure: not sufficient

cast post and core

glass fiber post with composite resin core

glass fiber post with fiber-reinforced core

(With ferrule/without ferrule)

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Two mm crown ferrule surrounding remaining toothstructure enhanced fracture resistance of anterior

teeth which were restored with a cast post and core

and metal ceramic crowns.

Height of the ferrule: resistance form of the tooth

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Purpose

To evaluate the effect of post, core, crown

type, and ferrule presence on the

deformation, fracture resistance, and fracture

mode of endodontically treated bovine

incisors

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Material and methods. Specimen preparation

Restoration fabrication

Strain measurement tests

Fracture tests

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Specimen preparation 180 bovine 12 treatment groups (n=15).

Treatment variations were: with or without

ferrule, restored with cast post and core, glassfiber post with composite resin core, or glassfiber post with fiber-reinforced core, andmetal- or alumina-reinforced ceramic crown

(n=15).

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Selected incisors: similar dimensions (coronal volume within 10% of the

average)

roots without curvature

free of cracks or defects

stored for no longer than 3 months

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External debris removed with a hand scaler Teeth were stored in 0.2% thymol solution (Isofar,

Duque de Caxias, Brazil).

Anatomic crowns of all teeth: sectioned perpendicular

to the long axis water-cooled diamond disk (no. 7020;

KG Sorensen, Barueri, Brazil)

Specimens with ferrule15.0 mm from the apical limit

Specimens without ferrule 13.0 mm from the apical limit

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Root canal treatment was done

Specimens with ferrules: prepared with cylindrical

diamond rotary cutting instrument

Post space obtained initially with a heated

instrument Gates-Glidden

Post space: 8.0 mm for the groups without ferrule

10.0 mm for the groups with ferrule

( preserving 5.0 mm of guttapercha at the apex)

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Roots:Embedded in polystyrene resin (AM 190 resin;AeroJet, Santo Amaro, Brazil)

Roots with no ferrule: 2.0 mm below cervical limits

Roots with ferrule: 4.0 mm below cervical limits

Periodontal ligament simulated: polyetherimpression material (Impregum Soft; 3M ESPE, St.

Paul, Minn).

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Restoration fabrication

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Without ferrule(90)Ferrule(90)

cast

Post &

core (Cpc)

glass fiber

post with

composite

resin core

(Gfr)

glass fiber post

with fiber-

reinforced

core (Gfc)

glass fiber

post with

fiber-

reinforced

core (Gfc)

glass fiber post

with composite

resin core (Gfr)cast

Post & core

(Cpc)

metal crowns (Mc)/alumina-reinforced ceramic crowns (Cc)


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1) FCpcMc, root with ferru restored with cast post and coreandmetal crown

2) NfCpcMc, rootwithout ferrule, restored with castpost and core

and metal crown;

3) FcpCc, root with ferrule, restored with cast post and core and

ceramic crown

4) fCpcCc, root without ferrule, restored with cast post andcore

and ceramic crown

5) FGfrMc, root with ferrule, restored with glass fiber post,

composite resin core,metal crown

6) NfGfrMc, root without ferrule, restored with glass fiber

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(7) FGfrCc, root with ferrule, restored with glass fiber post,

composit resin core, and ceramic crown;(8) NfGfrCc, root without ferrule, restored with glass fiber

post, composite resin core, and ceramic crown

(9)FGfcMc, root with ferrule, restored with glass fiber post,fiber-reinforced core, and metal crown

(10) NfGfcMc, root without ferrule, restored with glass fiberpost, fiber-reinforced core, and metal crown

(11) FGfcCc,root with ferrule, restored with glass fiber post,fiber-reinforced core, and ceramic crown

(12) NfGfcCc, root without ferrule, restored with glass fiberpost, fiber-reinforced core, and ceramic crown

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Results Buccal strains

Proximal strains

Fracture resistance and mode

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Proximal strains Groups with metal crowns (Mc) were significantly higher

(P=.005) than forgroups with alumina-reinforced ceramiccrowns (Cc), irrespective of core or ferrule presence

Groups without ferrule (Nf) showed significantly higher(P=.017) than the groups with ferrule (F), irrespective ofcore or post type

Glass fiber posts produced significantly higher (P=.023)than the cast post and core in the groups with a metalcrown but no ferrule

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Fracture resistance and mode Within the ferrule and no ferrule groups (F and Nf):

not significantly affected by post type, core, or crown

type

However, without a ferrule, incisors restored with a

metal crown presented significantly lower (P=.013)

values, irrespective of core or post type

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Results: Ferrule presence did not significantly influence the

buccal strain and fracture resistance for the ceramiccrown groups, irrespective of core and crown type.

Ferrule presence resulted in lower strains and higherfracture resistance in the metal crown groups,irrespective of core

The cast post and core showed lower strain values thangroups with glass fiber posts when restored with metalcrowns.

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To have comparable conditions between the test

specimens, this study used bovine incisors of animals

of similar age instead of human incisors

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The incisors in this study were

loaded statically in nondestructive

and destructive tests. During oral

function, teeth are subjected to dynamic

masticatory and thermal loading

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The results of the present study

confirmed that the presence of a 2.0-

mm ferrule increased the fracture resistance

of the endodontically treated

incisors, irrespective of crown, core,

or post type

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Although most studies agree that

ferrules improve fracture strength,

sufficient coronal structure is often

absent in clinical situations.10 Groups

without a ferrule restored with ceramic

crowns showed higher fracture

resistance and lower strains than

those restored with metal crowns

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The results of the present

study did not prove the efficacy of this

product, perhaps because the integration

between the fiber-reinforced core and the post coronal portion

was determined by the properties of

the resin cement layer

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In summary, it was demonstrated that strain gaugemeasurements could detect subtle differences in

mechanical response even when fracture resistance

results could not.

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Conclusion:1) The presence of a ferrule is a determining factor in

the strain distribution and fracture resistance of

endodontically treated incisors restored with metalcrowns, irrespective of the core type.

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2. For metal crown restorations with no ferrule, cast

post and cores showed better biomechanical

performance than glass fiber posts

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3. With respect to biomechanical behavior, alumina-reinforced ceramic crown restorations were not

influenced by the core type

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T

he restored incisors were loaded at a 135-degreeangle, and the deformation was measured using strain

gauges placed on the buccal and proximal root

surfaces.

Specimens were subsequently loaded to the point offracture.

Strain and fracture resistance results were analyzed by

3-way ANOVA and Tukey HSD tests (=.05).

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Critical analysis Subjects

m/m

Resuts

conclusion

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subjects

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- . -

2010;104:379-388)

Both long and short fiber posts provided root

fracture resistance comparable to that of SS

posts. For metal posts, extending the post

length does not effectively prevent root

fracture in restored teeth.

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