The Simultaneous Modeling Technique: closing gaps in ...

58THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY

CLINICAL RESEARCH

Correspondence to: Gaetano Paolone, DDS

Viale dei Quattro Venti, 233, 00152 Rome, Italy; Email: [email protected]

The Simultaneous Modeling

Technique: closing gaps in posteriors

Salvatore Scolavino, DDS

Private Practice, Nola, Naples, Italy

Gaetano Paolone, DDS

Private practice, Rome, Italy

Adjunct Professor, Restorative Dentistry, Dental School, Vita-Salute San Raffaele University,

Milan, Italy

Giovanna Orsini, DDS, PhD

Associate Professor, Restorative Dentistry, School of Dentistry,

Polytechnic University of Marche, Ancona, Italy

Walter Devoto, DDS

Private and Referral Practice, Sestri Levante, Italy

Lecturer, Master of Endodontics and Restorative Dentistry, University of Siena, Italy

Visiting Professor, University of Marseille, France, and International University of Catalonia,

Barcelona, Spain

Angelo Putignano, MD, DDS

Professor, Restorative Dentistry, Head of Department of Endodontics and Operative Dentistry,

School of Dentistry, Polytechnic University of Marche, Ancona, Italy


SCOLAVINO ET AL

Abstract

Direct posterior restorations represent

a widespread procedure in daily prac-

tice. Occlusal layering is often con-

sidered a complex task, generally not

predictable and often requiring several

occlusal adjustments. Moreover, direct

posterior restorations are time consum-

ing, as many small increments must be

applied and cured individually to con-

trol shrinkage stress. Several authors

have proposed different material layer-

ing techniques for posteriors.1-8 The au-

thors of this article propose a simplified

approach, which primarily aims to help

the clinician perform quick, simple, pre-

dictable, and natural-looking occlusal

modeling, reducing the need for oc-

clusal adjustments.

(Int J Esthet Dent 2016;11:58–81)



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Introduction

Occlusal anatomy is very variable; it can

be steep, flat, smooth or very irregular

(Fig 1). All these surface characteris-

tics are unique, and the clinician should

avoid trying to replicate identical mor-

phology for every restoration.

When part of the occlusal anatomy

is missing, due either to caries or an

unsuitable filling, an accurate analysis

of the anatomical information of the re-

maining occlusal tissue is very useful.

Information taken from the residual oc-

clusal table tissue such as steepness of

the ridges, position of primary and sec-

ondary ridges, grooves, etc, allows for

the creation of a custom modeling rather

than a standardized one.

The technique proposed in this article

is based on the following points:

Multiple, simultaneous yet segmented

(not in contact) composite increments

to define occlusal anatomy.

Occlusal modeling always starts from

a standardized cavity depth.

Use of the following anatomical in-

formation: a) from the tooth before

its preparation; b) from the residual

healthy tooth tissue after preparation;

c) from the adjacent teeth; and d) from

the contralateral.

The advantages of this technique are:

1. Time saving: simultaneous compos-

ite increments reduce the number of

curing cycles.

2. Easier modeling: the centripetal pro-

jection of the peripheral sound tissue

means fewer occlusal adjustments.

3. Occlusal preview: preview, verify,

and modify the position, extent, and

orientation of the simultaneous ridg-

es before light curing.

4. Shrinkage management: due to the

non-contact of multiple increments,

shrinkage stress can be controlled.

5. Standardized procedure: a standard-

ized cavity depth as a starting point

for the occlusal layer makes the pro-

cedures repeatable.

The limits of this technique are that the

peripheral sound tissue, from which the

central projection starts, can be discon-

tinued by the loss of one or both marginal

Fig 1 (From left to right): Variability in occlusal surface anatomy morphology.


SCOLAVINO ET AL

ridges, or one or more cusps. Clinicians

can face two different situations with two

different outcomes:

1. Marginal ridges: these can be re-

stored in a predictable way using

proven techniques.9

2. Cusps: freehand modeling of a cusp

(height, thickness, and tip position) is

difficult, arbitrary, and unpredictable,

mainly due to the lack of references.

Due to rubber dam isolation, it is im-

possible to verify the interocclusal

relationship. Indirect restorations can

provide a more practical and predict-

able solution for the clinician in these

situations.

Description of the

technique

Knowledge of dental anatomy is cru-

cial. Although this technique presents a

workflow that allows for simplified mod-

eling in posteriors, the main aspects

of occlusal anatomy and their possible

variability should be known for every

tooth, including the average position of

grooves, pits, ridges, triangular ridges,

oblique ridges, and marginal ridges, as

well as the size ratio of ridges.

Observation

The preliminary stage of gathering in-

formation should be performed prior to

rubber dam isolation.

Analysis of the teeth to be treatedObservation plays a very important role

in the initial stage. If the teeth to be treat-

ed are not already destroyed or do not

contain incongruous extensive restor-

ations, the analysis of these teeth allows

the clinician to define the position of the

grooves and pits, as well as the orienta-

tion and steepness of the crestal slopes.

Analysis of the adjacent teethThe depth of the grooves, the inclina-

tion of the crestal slopes, and the height

of the marginal ridges (in the case of

class II) can be quickly detected from

the neighboring teeth.

Cavity requirements

Cavity floorThe technique described here is referred

to as modeling the anatomy of the oc-

clusal layer. This technique starts from a

simplified cavity floor, with no anatomic

pre-modeling and approximately 1 to

2 mm deeper than the marginal ridge

(Fig 2). The cavity floor is then flat or

slightly rounded.

A cavity depth of 1.5 to 2 mm allows

for an average depth of 3 to 3.5 mm

Fig 2 The modeling of the occlusal layer starts

from a standardized cavity depth.

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Fig 3 Grooves and pits are generally 3 to 3.5 mm from the top of the cusps.

Fig 4 A standardized cavity floor depth of about 1 to 2 mm (measured at the marginal ridge) allows for

reproducibility of the correct position and depth of pits and grooves.

Fig 5 Simultaneous increments are applied to each corresponding cusp.

SCOLAVINO ET AL


Fig 6 Increments are pushed centripetally in order to define ridges.

Diagrams 1 to 5 1 and 2: Simultaneous increments. 3: Centripetal projection of composite increments

to define ridges. 4 and 5: Excess removal following the residual anatomy.

from the top of the buccal cusp tip to the

grooves (Figs 3 and 4), as suggested by

Kano.10

The above-mentioned cavity floor

can be obtained with different materials

(flowables, bulk-fill materials, regular

composites), depending on the clinical

situation and the clinician’s choice.

Cuspal thicknessCuspal thickness is ≥ 2 mm. Structural

issues related to cuspal thickness thin-

ner than 2 to 2.5 mm have been report-

ed.11,12 Cusps thinner than this value

should be lowered and, as previously

mentioned, an indirect restoration could

be a more predictable solution.

Cuspal ridges

The first composite increments are per-

formed simultaneously, in correspond-

ence with two or more cusps (Fig 5; Dia-

grams 1 and 2) in order to better preview

1 2 3 4 5

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Fig 8 All ridge characteristics (width, length, height, etc) can be modified simultaneously before light

curing.

Fig 9 Composite is spread on the margin with brushes for margin adaptation.

Fig 7 Excesses are removed by dragging a sharpened instrument along the sound residual tissue.

SCOLAVINO ET AL


cuspal relationships. Composite is then

squeezed and pushed toward the cent-

the ridge bodies (Diagram 3). To con-

trol shrinkage stress, ridge extensions

should not be in contact with each other.

The occlusal table will be closed in the

final step, allowing further anatomy ad-

justments. Any excess composite can

be removed by dragging along a sharp-

ened instrument parallel7 to the sound

residual tissue (Fig 7; Diagrams 4 and

5). Final ridge adjustments are done be-

fore light curing (Fig 8). Margin adapta-

tion is achieved by spreading compos-

ite on the margin with a brush (Fig 9;

Diagrams 5 to 7).

In this step, we define the anatomic

sketch that outlines:

1. Main ridge orientation, location, and

volume.

2. Approximate path of the primary

and secondary grooves.

3. Approximate position of the main pits.

In this step, the clinician can check

and correct length, orientation, and

ridge volumes before light curing (Dia-

grams 8 and 9). The first increments can

be slightly undersized, both to manage

shrinkage stress and to allow appropri-

ate corrections with further increments.

Marginal ridges

The mesial and distal ridges are mod-

eled in the same way as the cuspal

ridges (Fig 10). Composite is added as

Fig 10 Definition of marginal ridges. (From left to right): simultaneous application, centripetal spreading,

excess removal. A different color has been used for teaching purposes.

Diagrams 5 to 9 5 to 7: Once excess is removed, composite is spread on the margin with a brush.

8 and 9: All the increments are light cured at once.

5 6 7 8 9

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Diagrams 10 to 13 First increments should be applied and cured simultaneously. When grooves and

pits need to be defined, increments should be cured one by one.

Diagrams 14 to 17 A natural-looking groove is obtained by pushing a drop of composite towards a

cured one.

Fig 11 Composite is spread on the margin.

small drops, and spread with a sharp-

ened instrument. Excesses are removed

by pushing a sharpened probe into the

sound tissue. Sometimes, they are split

into two or more ridges, and this can be

detected on the residual marginal crest.

Triangular ridge extension merges into

the distal or mesial triangular pit. Mar-

ginal ridge composite adaptation is

obtained through the use of brushes

(Fig 11).

10 11 12 13

14 15 16 17

SCOLAVINO ET AL


Closing the occlusal table

The central gap, derived from the in-

complete modeling of the vertexes of the

ridges, is closed by adding small drops

of composite and squeezing them to es-

tablish the correct final relationship that

defines grooves and pits (Diagrams 10

to 13).

In this step, composite increments are

pushed towards an already cured incre-

ment. To obtain a natural-looking groove,

composite should be pushed downwards

with instruments or brushes to meet the

opposite cured cusp (Diagrams 14 to

17). Increments are then smoothed with a

brush (Diagram 18). A sharpened instru-

ment can be used to redefine pits and

grooves (Diagram 19), and final light cur-

ing is performed (Diagrams 20 and 21).

Closing the occlusal table can be

achieved in the following ways:

1. Extending the vertex of a ridge with

a small drop of composite (Fig 12).

2. Extending the marginal ridges

(Fig 13).

3. Adding the oblique ridge in the

maxillary molars (Fig 14). In this

step, every little increment is added,

then modeled and cured.

4. Adding or extending secondary

ridges (Fig 15).

Diagrams 18 to 21 18: Composite is spread following the anatomic profile. 19: A sharpened instrument

can be used to redefine pits and grooves if they disappear during modeling. 20 to 21: Final light curing of

the increment.

Fig 12 The vertex of a ridge can be lengthened with a little increment.

18 19 20 21

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Fig 15 Secondary ridges, detected on the peripheral ridge, are added with a small drop of composite

and modeled with a sharpened instrument.

Fig 13 A centripetal extension of the marginal ridge is another way to close the occlusal table.

Fig 14 The oblique ridge can be modeled in one increment, and its central groove is generally not deep.

SCOLAVINO ET AL


Fig 16 Small cavities: one ridge is modeled and cured at a time.

Fig 17 A natural-looking groove can be obtained by pushing a small drop of composite towards a well-

defined cured one.

Small cavities

The technique presented here is applica-

ble not only to large cavities, where many

ridges have to be restored, but also to

small cavities. When the clinician has to

deal with small cavities, the steps shown

in Diagrams 1 to 9 can be skipped, and

those shown in Diagrams 9 to 21 should

be followed, relative to closing the oc-

clusal table. To give pits and grooves

a natural aspect, increments should be

Materials and shades

While this article describes a modeling

technique for occlusal anatomy, it is

not dependent on the type and shade

of composite used. The authors do not

ascribe much importance to color in

posterior direct restorations, but believe

that a correct anatomical modeling rep-

resents the best mimesis, independently

of the shades used.

CLINICAL RESEARCH


Shrinkage in the occlusal layer

Although none of the layering tech-

niques can avoid the effects of poly-

merization shrinkage,13 many studies

have shown that an incremental layer-

ing technique results in better perfor-

mance than does bulk placement.14-17

Shrinkage stress seems to relate more

to the volume of the restoration than to

its ‘C’ factor.18,19

In a multi-layered restoration, if the fi-

nal occlusal increment is cured all at

the same time, it produces the highest

cuspal deflection.20

The shrinkage direction of compos-

ite increments is affected by both the

bonded surfaces and the free ones.21

The simultaneous split incremental pro-

cedure proposed here is based on re-

specting all the above-mentioned issues

aimed to reduce polymerization shrink-

age stress. In particular, among all the

composite ridges, the final connection

(closing the occlusal table) is achieved

with only a little increment that fills the

small residual occlusal gap in the least

stressful way.

Clinical cases

The following clinical cases have been

restored using the technique described

in this article.

Case 1

Fig 18 Fig 19 Isolation. Fig 20 Cavity preparation.

SCOLAVINO ET AL


Fig 21 After adhesion and flowable composite on the bottom of the cavity, simultaneous increments

are placed to restore DL and MB ridges. Fig 22 Ridges are driven centripetally. Residual anatomy on

sound tissue is important to understand a ridge’s orientation and steepness. Margin adaptation is achieved

through the use of brushes. Fig 23 Simultaneous increments on ML and DB.

Fig 24 Closing the occlusal table: a drop of composite is placed on the apex of DB to extend it. Fig 25 The

ridge tip of DB is extended centripetally. Fig 26 DB ridge extended. To achieve a natural-looking anatomical

modeling in mandibular molars, the vertices of ridges do not generally merge in the same pit.

Fig 27 Distal marginal ridge is added, as well as secondary ridges on the cusps of ML and DL. A small

increment is added on the ridge tip of DL to define the distal groove. Fig 28 Staining is placed to outline

anatomy and to give a better three-dimensional aspect. Fig 29 Final result.

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Case 2

Fig 30 Initial situation and isolation.

Fig 31 Cavities prepared.

Fig 32 After adhesion, a flowable base is placed

at the bottom of the cavities, and the buccal surface

Fig 33 Simultaneous placement of ridges and

centripetal projection in accordance with residual

anatomical information.

SCOLAVINO ET AL


Fig 34 Final result before and after dental dam

removal.

Fig 35

Fig 38 Final result. Fig 39 Final result after dental dam removal.

Case 3

Fig 36 Initial situation, isolation, and cavity prep-

aration.

Fig 37 A base is placed at the bottom of the cav-

ity, after which simultaneous increments are placed

to define MB, DB, and MP ridges. Marginal ridges

and secondary ridges are added to complete the

occlusal table.

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Fig 40 -

suitable restorations.

Fig 41 On 4.5, class II is transformed to class I.9

Fig 42 A small amount of flowable material is

placed to level the bottom of the cavities.

Fig 43 Simultaneous increments are placed in-

side the opposite cusps of the first molar.

Fig 44 but the extensions of the ridges are not in contact.

After having defined the length and orientation of

the ridges, composite is spread on the margin of

the restoration with a brush for better marginal ad-

aptation and to make it anatomically consistent with

the residual tooth structure. On 4.7, increments are

placed for ML and DB ridges.

Case 4

SCOLAVINO ET AL


Fig 45 On 4.7, ridges are pushed centripetally

and the margin is smoothed with a brush, as de-

placed for all the three ridges.

Fig 46 4.5: projections of ridges pushed centrip-

increments for MB and DL ridges.

Fig 47 -

ments on the tip of the ridges to close the occlusal

table.

Fig 48 Stains have been placed to enhance the

three-dimensional aspect of the restoration.

Fig 49 Final result after dental dam removal. Fig 50

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Fig 52

Fig 53 Two sectional matrixes are placed in order

to restore marginal ridges. DP cusp is missing. As it

is quite small, it will be restored directly.

Fig 54 The occlusal perimeter restored.

Case 5

Fig 51 Final radiograph.

SCOLAVINO ET AL


Fig 55 Increments for DB and MP ridges. Fig 56 Increments for MB and DP ridges.

Fig 57 MB and DP ridges pushed to the center,

and margin smoothed with a brush.

Fig 58 Increments for the mesial marginal ridge

and the oblique ridge.

Fig 59 Increments for the distal marginal ridges

and for a DB secondary ridge.

Fig 60 Occlusal anatomy finished.

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Fig 62 Final result after dental dam removal.

Sound tissue is dehydrated.

Fig 63

Fig 64 Final radiograph.

Fig 61 Staining.

SCOLAVINO ET AL


Fig 65 Fig 66 After isolation, cavities are prepared.

Fig 67 Self-etching adhesive system with enamel

pre-etching has been performed.

Fig 68 A small amount of flowable composite has

been placed on the floor cavities.

Fig 69 (Left): Contemporary increments of disto-

buccal and mesiolingual cusps. (Right): Mesiolin-

gual and distobuccal.

Fig 70 Last increments for small cavities and

definition of grooves.

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Fig 71 An oblique view before dental dam removal.

Fig 72 Final result after dental dam removal.


SCOLAVINO ET AL

Conclusion

Direct posterior restorations are a com-

mon task in daily practice. This article

describes a simplified approach, based

on the simultaneous increments for mod-

eling the occlusal table according to the

peripheral residual anatomy. This helps

clinicians to perform simpler, quicker

restorations that need fewer occlusal

adjustments.

Acknowledgments

The authors would like to thank Dr Gurvinder Bhirth

and Dr Ronan O’Donoghue for their valuable sug-

gestions and their help with proofreading this article.

References

1. Tjan AH, Bergh BH, Lidner

C. Effect of various incre-

mental techniques on the

marginal adaptation of class

II composite restorations. J

2. Deliperi S, Bardwell DN. An

alternative method to reduce

polymerization shrinkage

in direct posterior compos-

ite restorations. J Am Dent

3. Lopes GC, Vieira LC, Araujo

E. Direct composite restor-

ations: a review of some clin-

ical procedures to achieve

predictable results in pos-

terior teeth. J Esthet Restor

-

sion 32.

4. Boer WM. Simple guidelines

for aesthetic success with

restorations. Pract Proced

247;quiz 248.

5. Schlichting LH, Monteiro S Jr,

Baratieri LN. A new proposal

to optimize the occlusal

margin in direct resin com-

posite restorations of poster-

ior teeth. Eur J Esthet Dent

-

tal and stratified layering

techniques to produce an

esthetic posterior composite

restoration with a predictable

prognosis. J Esthet Restor

7. Dietschi D, Spreafico R.

Adhesive metal-free restor-

in the aesthetic treatment of

posterior teeth. Berlin: Quin-

tessence, 1997.

8. Baratieri LN, Monteiro Júnior

S, Correa M, Ritter AV.

Posterior resin composite

restorations: a new tech-

nique. Quintessence Int

9. Bichacho N. The centripetal

build-up for composite resin

posterior restorations. Pract

Periodontics Aesthet Dent

10. Kano P. Challenging Nature:

Wax-up Techniques in Aes-

thetics and Functional Occlu-

sion. Quintessence, 2011.

11. Krifka S, Anthofer T, Fritzsch

M, Hiller KA, Schmalz G,

Federlin M. Ceramic inlays

and partial ceramic crowns:

influence of remaining cusp

wall thickness on the margin-

al integrity and enamel crack

formation in vitro. Oper Dent

12. Fichera G, Re C. Restauri

estetico-adesivi indiretti:

modello per diagnosi di con-

figurazione cavitaria. Den-

13. Loguercio AD, Reis A,

Schroeder M, Balducci I,

Versluis A, Ballester RY.

Polymerization shrinkage:

effects of boundary condi-

tions and filling technique of

resin composite restorations.

14. Wilson EG, Mandradjieff M,

Brindock T. Controversies

in posterior composite resin

restorations. Dent Clin North

15. Soares CJ, Bicalho AA, Tant-

birojn D, Versluis A. Polymer-

ization shrinkage stresses

in a premolar restored with

different composite resins

and different incremental

techniques. J Adhes Dent

Effect of layering methods,

composite type, and flow-

able liner on the polymer-

ization shrinkage stress of

light cured composites. Dent

17. Park J, Chang J, Ferracane

J, Lee IB. How should com-

posite be layered to reduce

shrinkage stress: incremental

or bulk filling? Dent Mater

18. Braga RR, Boaro LC, Kuroe

T, Azevedo CL, Singer JM.

Influence of cavity dimen-

sions and their derivatives

(volume and ‘C’ factor) on

shrinkage stress develop-

ment and microleakage of

composite restorations. Dent

19. Rodrigues FP, Silikas N,

Watts DC, Ballester RY. Finite

element analysis of bonded

model Class I ‘restorations’

after shrinkage. Dent Mater

20. González-López S, Lucena-

Martín C, de Haro-Gasquet

F, Vilchez-Díaz MA, de

Haro-Muñoz C. Influence of

different composite restor-

ation techniques on cuspal

deflection: an in vitro study.

21. Versluis A, Tantbirojn D,

Douglas WH. Do dental

composites always shrink

toward the light? J Dent Res

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