posterior indirect adhesive restorations: updated

204THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY

SUMMER 2017

CLINICAL RESEARCH

Posterior indirect adhesive

restorations: updated indications

and the Morphology Driven

Preparation Technique

Marco Veneziani, DDS

Private practice, Vigolzone (PC), Italy

Visiting Professor, University of Pavia, 2007–2012

Active member, Accademia Italiana di Conservativa

Active member, Italian Academy of Esthetic Dentistry

Active member, International Academy for Digital Dental Medicine

Correspondence to: Dr Marco Veneziani

Via Roma 57, 29020 Vigolzone (PC), Italy; Tel/fax: +39 0523 870362; Mobile: +39 3351 435187;

Email: [email protected]; [email protected]


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VENEZIANI

Abstract

The aim of this article is to identify the

indications for adhesively cemented

restorations and to provide a correct

step-by-step protocol for clinicians.

New cavity preparation principles are

based on morphological considerations

in terms of geometry (maximum profile

line and inclination of cusp lines), and

structure (dentin concavity and enamel

convexity). In this article, we discuss

previous preparation concepts that were

not designed purely for adhesive restor-

ations and were therefore not conserva-

tive enough or suitable for adhesive pro-

cedures. The novel cavity shape consists

of continuous inclined plane cavity mar-

gins (hollow chamfer or concave bevel)

on axial walls, whenever they are coro-

nal to the equatorial tooth line. A 1.2 mm-

thick butt-joint preparation is performed

in the interproximal box and on the axial

walls when the margins are apical to

the equatorial line. The occlusal surface

is anatomically prepared, free of slots

and angles. The author’s suggestion is

to avoid shoulder finish line preparation

around cusps, occlusal slots, and pins,

as they are less conservative, incompat-

ible with adhesive procedures, and in-

volve unnecessary dentin exposure. The

clinical advantages of this new “anatom-

ic” preparation design are 1) improving

adhesion quality (optimizing the cutting

of enamel prisms, and increasing the

available enamel surface); 2) minimiz-

ing dentin exposure; 3) maximizing hard

tissue preservation (the cavity being de-

signed for cementation with reinforced

composite resins, improvement of flow,

and removal of excess material); 4) op-

timization of esthetic integration due to

the inclined plane design, which permits

a better blending at the transition area

between tooth and restoration. These

preparation principles may be effec-

tively used for all adhesively cemented

restorations, both according to tradition-

al concepts (inlay, onlay, overlay) and

new ones (additional overlay, occlusal-

veneer, overlay-veneer, long-wrap over-

lay, adhesive crown). Thus, a balance

between restoration and prosthodontics

is created, which is characterized by a

more conservative approach.

(Int J Esthet Dent 2017;12:204–230)


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CLINICAL RESEARCH

with different techniques: direct, semi-

direct (intraoral and extraoral), and in-

direct. Decision criteria that guide clin-

icians in the choice of materials and

techniques can be divided into general

and local parameters. General param-

eters include the patient’s age, oral hy-

giene, motivation, caries risk assess-

ment, dietary habits, functional activity,

ergonomics, and financial resources;

local parameters include cavity shape,

thickness of remaining walls, position of

cervical margins, presence of cervical

lesions, presence of cracks, position of

the tooth, evaluation of the element in

preprosthetic function, and presence of

pulp disease or periodontal lesions.

Current indications for adhesive

cemented restorations

Direct techniques are traditionally indi-

cated in small- and medium-sized class

I and II restorations with cervical enam-

el.8 In these clinical situations, the first

choice is the direct technique, which

allows for high-level, predictable, and

repeatable results with a conservative

approach and excellent longevity. The

limitations of direct techniques, pointed

out in the literature of the mid-90s,5,8

have been reviewed and discussed in

many studies published in the 2000s,9-

13 from which it can be deduced that di-

rect techniques would be effective even

in cases of partial cusp coverage, ob-

taining a clinical outcome similar to indi-

rect techniques. Furthermore, the mere

lack of cervical enamel would no longer

represent an indication for the indirect

technique.

However, the direct technique on

teeth that have suffered a significant

Introduction

In modern restorative dentistry, the de-

velopment of adhesive procedures has

led to an important cultural and method-

ological revolution. Likewise, the evolu-

tion of restorative materials and adhesive

systems has influenced the approach to

restoring posterior teeth, modifying the

treatment plan considerably.1 The need

to perform adhesive restorations of pos-

terior teeth is not only linked to esthetic

purposes, but also to bioeconomic prin-

ciples, as well as to the possible bio-

mechanical strengthening of the remain-

ing tooth structure.2

Microhybrid and nanoparticle com-

posites are the materials most often sug-

gested for all kinds of cavities in posterior

teeth.3 However, the technical problems

of composites that are not yet solved are

curing shrinkage and dentin adhesion,

and the clinical problems relate to the

clinician’s ability to manage the tooth

isolation and adhesion, as well as re-

establish the original morphology. These

issues are particularly challenging when

the restorations are wide, and the cov-

erage of one or more cusps is neces-

sary. This has led to the development of

the semidirect and indirect techniques,

which allow for the complete curing of

the composite restoration before the lut-

ing procedures.4,5

Recently, the esthetic restoration and

rehabilitation of posterior teeth and full

arches has, through necessity, created

a new paradigm and balance between

operative “restorative” dentistry and

prosthodontics.6,7

According to the Geneva School

Classification of 1994, five composite

resins could be used for posterior teeth


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loss of hard tissue presents a number

of clinical issues: mandibular wear re-

sistance; control of shrinkage stresses;

possible postoperative hypersensitivity;

predictability of dentin adhesion; diffi-

culty of morphological restoration, with

particular attention to occlusal surface,

contact points, and emergence pro-

file.5,14-17 Consequently, in large cavi-

ties with cusp coverage, it is clinically

more favorable to use an adhesively ce-

mented restoration as the first treatment

choice.5

An “adhesive indirect restoration” has

been defined as a partial crown restor-

ation made in composite or full ceramic,

which has to be seated passively, and

adhesively cemented in a cavity char-

acterized by specific attributes. The aim

of this article is to define criteria for a

new cavity design for luted restorations,

and to analyze the different kinds of res-

torations, comparing conventional and

new concept cavity shapes.

Current indications for adhesively ce-

mented restorations could then be sum-

marized as:

Wide class II cavity with cusp cover-

age (one or more).

Restoration of large occlusal surface

compromised by wear and/or bio-

corrosion.

These indications are strengthened by

some cofactors, including the presence

of cervical enamel in a small quantity

(< 1 mm height, 0.5 mm large), or even

its absence; cervical concavity; the

necessity of performing multiple res-

torations in several quadrants with the

modification of the entire occlusion; and

the need to reestablish or increase the

vertical dimension.

The advantages4,5 of adhesively ce-

mented restorations compared to a di-

rect technique consist in creating an

ideal anatomy of occlusal surfaces,

with excellent control of contact points

and emergence profiles, and the pos-

sibility of an occlusion evaluation with

an articulator. Likewise, this technique

strongly decreases the curing shrinkage

that occurs outside the cavity, improving

the marginal sealing. The only remain-

ing curing shrinkage is in the thin layer

of resin cement. Moreover, photothermal

treatment (130°C for 7 min) improves the

degree of conversion of the composite

and the physiochemical properties of

the restoration.18-20 A further benefit

is the possible use of ceramic mater-

ials such as lithium disilicate-reinforced

glass-ceramics.

Operative procedures

for the indirect technique

According to the author’s experience

(since 1994) and data in the litera-

ture,4,5,21,22 a simple and clear procedure

is suggested for indirect adhesive res-

torations. The chronological sequence of

the clinical steps is:

1. Hard silicone matrix to impress the

anatomy of involved teeth (when the

anatomy is sufficiently preserved).

2. Opening of cavities or removal of

previous restoration and carious le-

sion removal.

3. Evaluation of enamel and dentin

thickness, and consequently reduc-

tion of unsupported tissues.

4. Composite build-up with immedi-

ate dentin sealing (IDS), and, if nec-

essary, cervical margin relocation

(CMR).

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5. Preparation and finishing of the cav-

ity according to new modified prin-

ciples (morphology driven prepar-

ation technique – MDPT).

6. Definitive impression with elasto-

mers (for singular elements, even

with a dual-arch technique through

a bite check).

7. Carrying out of the final restoration

(composite or ceramic) in the la-

boratory or chairside.

8. Verification of restoration adaption

before the application of rubber

dam.

9. Application of rubber dam, and ad-

hesive cementation procedure with

heated light-curing composite.

10. Finishing, polishing, and occlusal

control.

Evaluation of remaining thickness

and adhesive build-up

Since indirect restorations are indicat-

ed in wide cavities characterized by a

significant loss of hard tissue, a critical

thickness of remaining walls influences

the decision to maintain the wall or not,

particularly as the walls are often under-

cut and need proper restoration (build-

up or block-out).

The reduction of unsupported remain-

ing tissue is the following step, but prior

to adhesive build-up, so that a better

evaluation of wall thickness is possi-

ble, and the clinician can consequently

avoid exposure of non-hybridized dentin

after the preparation.

Occlusal tissue reduction depends

on four points:

1. Minimal thickness of material (either

composite or lithium disilicate) of at

least 1.0 to 2 mm.22

2. Enamel quantity that is not support-

ed by underlying dentin. The wall

must be reduced until there is a suf-

ficient quantity of dentin to support

the enamel.

3. Enamel thickness. Measurement of

the remaining cusp is not enough to

determine its resistance; both enam-

el and dentin thicknesses must be

considered.

4. The importance of occlusal func-

tional strain during chewing.

After occlusal reduction, the build-up

must be performed for the following rea-

sons:

To obey the fundamental principle of

IDS.23 IDS has shown an improved

microtensile bond strength compared

to delayed dentin sealing (DDS).

To fill the undercuts that inevitably

form during caries removal.

To provide a correct cavity geometry.

To produce an optimal restoration ma-

terial thickness so as to permit a cor-

rect conversion of the light-curable,

preheated composite used for adhe-

sive cementation.24,25

Furthermore, it is possible to cement

without anesthesia, because exposed

dentin has already been hybridized and

covered by a pre-layer of composite.

The first-choice material for the build-up

is hybrid highly reinforced mini particles

of composite used with the modified du-

al-bonding technique.26 When interoc-

clusal free space is poor, a mini build-up

with only a thin layer of flowable com-

posite is indicated.

In case of deep cervical margins

without biological width violation, it is

clinically convenient to move the mar-

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gins coronally, applying a layer of highly

reinforced flowable composite27-29 (1 to

1.5-mm thick). When the position of cer-

vical margins does not allow for the cor-

rect isolation with rubber dam, or there

is a biological width violation, a surgical

approach is necessary.30

Preparation principles for indirect

restoration

Conventional principles4 would suggest

a cavity with a 6- to 10-degree divergent

wall, internal rounded angles, finishing

of enamel with sharp and not beveled

margins, smooth and well-defined walls,

and a general plain design. Restoration

margins do not have to coincide with oc-

clusal contacts.

The following parameters that influ-

ence and lead the cavity design4,21,31,32

are essential:

Thickness of remaining walls (in order

to maintain them) has to be ≥ 2.0 mm

in vital teeth,4 (latest articles report

values of 1 mm22), and ≥ 3.0 mm in

endodontically treated teeth.33-35

Width of occlusal isthmus has to

be ≥ 2 mm for composite and lithium

disilicate glass-ceramic.

Presence or absence of marginal

ridges, and, consequently, presence

of interproximal box has to be evalu-

ated on three space planes.9,36

Thickness of material for cusp cov-

erage has to be ≥ 1 to 1.5 mm22,37,38

for composite and lithium disilicate

(pressed or CAD/CAM), and ≥ 2 to

2.5 mm for feldspathic ceramic and

leucite-reinforced glass-ceramic.

Interproximal overjet has to be possi-

bly ≤ 2 mm. The fracture risk of the re-

stored marginal ridge increases when

the overjet is too large.4

New cavity design (Morphology

Driven Preparation Technique)

(Figs 1 and 2)

The principles of traditional cavity design

were derived from preparations meant

for indirect non-adhesive restorations.

These were characterized by a cav-

ity design that ensured retention by the

Fig 1 New morphology driven preparation tech-

nique (MDPT) in two maxillary molars.

Fig 2 Indirect composite restorations after adhe-

sive cementation.

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placement of shoulders, occlusal slots,

and eventually pins, which could expose

sound dentin with a significant loss of

structural tissue (Fig 3). Apart from this,

conventional preparations did not con-

sider the real morphostructural and his-

toanatomical course in the tooth crown.

Moreover, no clear data are reported in

the literature about the correct level of

the shoulders on the axial walls, leaving

clinicians the task of preparing them ac-

cording to their clinical experience. Fur-

thermore, the traditional cavity design

is not completely suitable for adhesive

cementation because of the presence of

isthmuses, shoulders, and rounded an-

gles. Also, the width of the shoulders and

of the onlays themselves seems to be

excessive, and leads to an inadequate

degree of luting composite conversion.

Fig 3 Clinical examples of old, conventional adhesive preparations of maxillary and mandibular molars

and premolars.

Fig 4 Clinical examples of new MDPT for adhesive restorations of maxillary and mandibular molars and

premolars.

MAXILLARYOLD CONVENTIONAL ADHESIVE PREPARATIONSMANDIBULAR

NEW MODIFIED ADHESIVE PREPARATIONS

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The principles of MDPT (Fig 4) are

intended to achieve these improve-

ments:

To minimize as much as possible the

loss of healthy tooth tissue by reduc-

ing the areas of dentin exposure.

To guide tissue reduction of the oc-

clusal surface with depth cuts or, bet-

ter still, with a silicone index for thick-

ness control.

To reduce the width of the margins

prepared as a shoulder, where indi-

cated.

To define a margin design that could

improve the quality of the adhesion,

optimizing the cutting of the enamel

prisms and creating a greater surface

of enamel.

To improve the smooth insertion of the

restoration during cementation.

To improve the esthetics of the transi-

tion zone between the tooth and the

restoration. In chronological order,

the preparation sequence is the prep-

aration of the interproximal box, the

anatomical reduction of the occlusal

surface, and the definition of the mar-

gins on the axial walls. The margin

definitions differ in maxillary and man-

dibular teeth. The design of the axial

margins varies according to the resid-

ual sound tissue, the margin position,

the inclination and slope morphology

of the cusp, and the maximum tooth

contour line (equator). The prepar-

ation is ultimately guided by the ana-

tomical and structural morphology of

the teeth.

Principles of the MDPT for premolars

and molars (Figs 5 to 9)

-

terproximal box (ideal thickness: 1 to

Fig 5 Maxillary bicuspid, endodontically treated

with a deep MOD cavity. There is a need for a com-

plete cuspal coverage to preserve it from fracture.

Fig 6 New MDPT for indirect adhesive overlay

restoration.

1.2 mm, max 1.5 mm) and rounded in-

side angles, obtained with a truncated

conical medium-grit diamond bur (diam-

eter 14) for the preparation, and fine-grit

diamond burs for finishing. The need to

define a box of reduced depth is intend-

ed to obtain an indirect restoration of a

regular thickness so as to guarantee the

resistance and at the same time allow

for the adequate conversion of the light-

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Fig 7 Scheme of new MDPT for maxillary bicuspid and molars.

Fig 8 New MDPT for indirect adhesive onlay and

overlay restorations.

curing adhesive and composite resin

material used for luting.24

2) Interior walls diverging 6 to 10 de-

grees, with sharp margins with rounded

inside angles. The residual axial walls

require a sharp preparation of the oc-

clusal margin, as the creation of inlays

beveled to occlusal would themselves

be susceptible to the risk of margin frac-

ture.

3) Occlusal anatomy reduction follow-

ing fissure direction and the resulting

proportion of the cusps, with diamond

conical truncated burs (diameters 14

and 18). The extent of the reduction is

a function of the strength parameters

of the restorative material, thus 1.0 to

2.0 mm is recommended. Occlusal slots

are not necessary; indeed, they should

MAXILLARY bicuspid and molars

Interproximal box: always

Axial walls: apically to

maximum contour line

Anatomical reduction

of the occlusal surface

Divergent walls

(6–10 degrees)

Inclined planes M–D, V–P

(chamfer)

Axial walls, coronal to


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Fig 9 Scheme of MDPT for mandibular molars and premolars.

be avoided. It is desirable to perform the

occlusal reduction guided by the depth

of cuts or, when possible, by properly

cut silicone indices detected on the

tooth before preparation.

4a) Preparation of axial walls with in-

clined plane (hollow chamfer). In the

mesiodistal and buccopalatal direc-

tions, a “hollow chamfer” or concave

bevel must be drawn with cylindrical

chamfer burs, using only the tip of the

bur. This design is indicated in cuspal

covering areas on axial walls coronal to

the line of maximum contour of the tooth.

For geometrical and structural reasons,

this occurrence is more frequent at the

level of the buccal and palatal walls of

maxillary molars and premolars, and the

buccal walls of mandibular molars and

premolars. This preparation of the mar-

gins allows for:

maximum preservation of sound re-

sidual tissue;

a geometrically induced increase of

the usable area of enamel for adhe-

sive procedures without exposure of

dentin areas;

margin configuration more favorable

for adhesion through cutting enamel

prisms almost perpendicular to their

longitudinal axis39,40 (unlike the draw-

ing of sharp margins, which would

cause a cut of prisms parallel to their

long axis) (Fig 10);

apical displacement of the finish line

(along the inclined plane), with a re-

duction of level differences between

cuspal vertices to be covered and the

MANDIBULAR molars and premolars

Interproximal box: always

Axial walls: apically to


Anatomical reduction

of the occlusal surface

Divergent walls

(6–10 degrees)

Inclined planes M–D, V–P

(chamfer)

Axial walls, coronal to


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bottom of the box, through the crea-

tion of “slip roads” curved without cor-

ners. Starting from the cervical margin

of the interproximal box, a curved line

that continues on the axial wall must

be created, which descends back to

then link with the opposite interproxi-

mal box;

a more gradual transition between the

preparation margins and the restor-

ation to obtain better mimicry, esthet-

ics, and transitional color blending of

the restoration.

4b) Preparation of axial walls, butt-joint

type. In some cases, when the cavity

margin is apical or at the equator line

as a result of substantial tissue loss that

involves the cervical third of the cusp, it

is convenient to prepare a sharp margin

(with the characteristics mentioned in

step 1) that coincides in the apicocoro-

nal direction with the level of the cutting

cusp. This occurrence is most frequent

at the lingual surfaces of mandibular

molars and premolars due to a different

geometry of the surfaces themselves

(Figs 8 and 9).

Rationale of the new modified cavity

design

The rationale of the cavity design de-

scribed above is the morphological

analysis of posterior teeth, with some

differences between maxillary and man-

dibular teeth, and with geometrical and

structural considerations justifying its use.

Maxillary molars and premolars (Fig 11)

Geometric considerations: the graphi-

cal representations drawn from Marseil-

lier41,42 (Fig 12) show that the maxillary

elements have buccal and palatal axial

walls definitely inclined and converging

in the coronal direction, with the maxi-

mum contour line (or dental equator)

positioned at the cervical third of the re-

spective walls. When the tooth requires

cusp covering, a sharp cut would cer-

tainly produce an oblique sectioning of

Fig 10 Margin configurations (hollow chamfer) more favorable for adhesion through the cut of enamel

prisms perpendicular to their longitudinal axis.

Sharp margin preparation Hollow chamfer preparation

Parallel to long axis enamel prisms Perpendicular to long axis enamel prisms

Cavity-surface angle

< 90 degrees

Cavity-surface angle

≥ 90 degrees

180 degrees 90 degrees

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Fig 11 Scheme of preparation with MDPT for maxillary molars and premolars.

the enamel prisms and an inadequate

acute margin restoration, while cusp

coverage with butt-joint preparation

would result in a substantial loss of

sound tissue associated with dentinal

exposure. It is evident that, whenev-

er the margin design is coronal to the

equator, an enamel cut with concave

profile (chamfer) is indicated because

it fits well with the inclination of the axial

walls from either a geometrical or bio-

logical (enamel prisms cut transversely

to their long axis) point of view.

At the interproximal level, the walls

converge apically, and the maximum

contour line is positioned in the occlusal

Fig 12 Geometric considerations (for maxillary molars and bicuspids) that underlie the MDPT. [Original

images from: Marseillier E. Les Dents Humaines Morphologie. Gauthier-Villars, 1967.]

MDPT: MAXILLARY molars and premolars PREPARATION

Inclined plane

(hollow chamfer)

“Slip roads”

Anatomical

reduction of the

occlusal surface

1–1.2 mm

Inclined plane

(hollow chamfer)

Inclined plane

(hollow chamfer)

Maximum contour line

(apical third of the tooth)

≥ 1.5 mm

≥ 1.5 mm

Inclined plane

(hollow chamfer)



Palatal

MORPHOLOGYGEOMETRIC CONSIDERATIONS

MAXILLARY molars and bicuspids

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third. Thus, the margin design can only

be a rounded shoulder with sharp mar-

gins. Any inclined or beveled plane is

contraindicated because it would shift

the margin apically, thereby reducing

the cervical enamel thickness.

Fig 13 Structural considerations (for maxillary molars and bicuspids) that underlie the MDPT.

Fig 14 MDPT: Different configuration of the buccal (inclined plane) and lingual (butt-joint) margins of the

mandibular molar, according to the tooth maximum contour line.

Structural considerations (Fig 13):

from a three-dimensional structural

analysis of human teeth43 it can be ob-

served that the contours of the convex

surface of enamel match concave pro-

files and sharp body dentin (sigmoid

MDPT: MANDIBULAR molars and premolars PREPARATION

Inner preparation line

Outer preparation line

Inclined plane

(hollow chamfer)



≥ 1.5 mm

≥ 1.0 mm



Lingual

≥ 1.5 mm

MORPHOLOGYSTRUCTURAL CONSIDERATIONS

MAXILLARY molars and bicuspids

structural analysis. Eur J Esthet Dent 2011;6:8–19.

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curve). The concavity of the dentin sur-

face is particularly evident and topo-

graphically located in the middle third,

and coronal to the equator. Consequent-

ly, it is obvious that, focusing on buccal

and oral surfaces, the gold standard for

cavity design constitutes a margin de-

sign with a beveled concave inclined

plane that cuts the enamel convexity,

following the dentin concavity without

exposing it.

Mandibular molars and premolars

(Fig 14)

Similar considerations should be ap-

plied to the mandibular posterior teeth.

Geometric considerations (Fig 15):

The buccal surfaces are inclined with

occlusal convergence, with a maximum

contour line located at the cervical third.

The lingual surfaces, however, are more

vertical, with the equator lines localized

to the occlusal third. For this reason, the

buccal margin is frequently represented

by a concave chamfer, with the excep-

Fig 15 Geometric and structural considerations (for mandibular molars and premolars) that underlie

the MDPT. [Original images from: Marseillier E. Les Dents Humaines Morphologie. Gauthier-Villars, 1967.]

tion of cases where a significant tissue

loss has undermined the wall up to the

cervical third. The margins on the lingual

side are more often represented by a

shoulder, because a loss of tissue that

induces a cusp cover often involves the

occlusal and middle third of the cusp,

with margins positioned under the equa-

tor line.

Structural considerations (Fig 15):

Even from a structural point of view, an

enamel convexity with a strong dentin

concavity in the middle and occlusal

thirds of the buccal walls is highlighted.

On the lingual side, a slightly convex

morphology of the enamel (on aver-

age) corresponds with a more recti linear

dentin surface. Consequently, based

on these considerations, the choice of

sharp shoulder margins is justified on the

lingual side. A concave margin can only

be prepared and finished in cases where

structural deficits constitute an indication

for a sharp cut in the coronal third of the

lingual cusp at the equatorial level.

MORPHOLOGYGEOMETRIC CONSIDERATIONS STRUCTURAL CONSIDERATIONS

structural analysis. Eur J Esthet Dent 2011;6:8–19.

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Adhesive restorations (conven-

tional and newly developed)

The new principles of preparation listed

above can be applied effectively to all

types of traditional adhesive restorations

(inlay, onlay, overlay) and help to define

a set of newly developed restorations

(additional overlay, occlusal-veneer,

overlay-veneer, long-wrap overlay, ad-

hesive crown).

Conventional indirect restorations

In inlay, onlay and overlay, the adhesive-

ly cemented restorations are traditionally

classified according to their type.

Inlays (Figs 16 to 18) are restorations

without cusp coverage, and would be

indicated in teeth with preserved vitality

in medium to large class II cavities (MO/

OD, MOD), with well-preserved buccal

and oral walls. Composite is the ideal ma-

terial. Currently, this type of restoration is

often performed with a direct technique,

thus obtaining equal predictability with a


Onlays (Figs 19 to 21) are restorations

that partially cover cusps, but not the en-

tire occlusal surface. They are indicated

in class II cavities of large dimensions

with lateral walls partially supported

without dentin cracks. In the case of en-

dodontically treated teeth, the presence

of at least one marginal ridge, and two

well-supported axial walls in continu-

ity with the marginal ridge itself, are re-

be used.44,45

Overlays are total cusp-coverage res-

torations, indicated in class II cavities of

large dimensions with unsupported ax-

ial walls and the absence of both mar-

ginal ridges. The presence of cracks in

Fig 16 Inadequate amalgam and composite res-

torations with evidence of recurrent decay.

Fig 17 Medium class II MO/OD cavities restored

with composite inlays without cuspal coverage.

Fig 18 11-year clinical follow-up, which shows

good morphological functional and esthetic main-

tenance.

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Fig 19 Inappropriate pre-existent restoration with

fracture of the material and noticeable marginal in-

filtration.

Fig 20 Onlay cavity preparation with partial cus-

pid coverage after thorough cleansing of the decay

and adhesive build-up.

Fig 21 8-year follow-up with excellent preserva-

tion of the morphology, function, esthetics, and mar-

ginal integrity.

Fig 22 Wide inadequate amalgam restoration

with residual and recurrent caries. The tooth was

asymptomatic.

Fig 24 Adhesive build-up and overlay prepar-

ation with circumferential butt joint (the cavity mar-

gins are all under the maximum contour line).

Fig 23 Thorough caries cleansing with vitality

maintenance of the tooth without pulp exposure.

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Fig 26 (a) First maxillary molar with tooth crack syndrome, previously restored with silver amalgam. The

wall thickness is good but there are enamel-dentin cracks. (b) Overall buccal and palatal cusps cut. Cracks

at the base of cusps are noticeable.

Fig 27 Cavity design definition (after adhesive

build-up) for overlay, with inclined planes of the axial

walls and connection on ramp with box (MDPT).

Direct composite restoration on tooth 15.

Fig 28 Monolithic, heat-pressed, painted lithium

disilicate (IPS e.max Press, Ivoclar Vivadent) over-

lay after adhesive cementation in isolated field with

rubber dam. Total cusp coverage with porcelain

significantly stiffens the crown and increases cusp

stabilization.

a b

Fig 25 Final restoration after finishing and polish-

ing, with adequate morphological and esthetic inte-

gration. The choice of composite as restoration ma-

terial makes a possible future re-intervention easier

(eg, for endodontic reasons).

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Fig 29 Restoration in oral cavity with excellent

morphological functional and esthetic integration,

and complete symptoms remission associated with

dentinal cracks.

Fig 30 Skeletal and dental deep bite. Implant-

prosthetic replacement of the maxillary right molar

after sinus lift. The opposing molars are extruded

and require occlusal plan remodeling.

Fig 31 To make the rehabilitation of sectors 1 and

4 easier, and to partially offset the deep bite, the

vertical dimension was increased with the execution

of additional overlays on the posterior teeth, and ad-

ditional palatal veneer on the anterior teeth.

enamel and dentin (in vital teeth), and

the absence of a marginal ridge in en-

dodontically treated teeth, requires to-

tal coverage, even in the presence of

residual walls of adequate thickness.

Composite (Figs 22 to 25) or ceramic

can be used. Ceramic (lithium disilicate

glass-ceramic) is the first-choice mater-

ial in the case of multiple restorations

with wide coverage. Furthermore, due

to its greater strength and ability to stabi-

lize the cusp, ceramic is the first choice

for teeth affected by cracked tooth syn-

drome, using it with a total cusps cover-

ing21,46-48 (Figs 26 to 29).

Newly developed indirect restorations

This new group of restorations is able to

meet the criteria of maximum preserva-

tion of healthy tissue and esthetics, and

helps to establish new boundaries be-

tween conservative practices and pros-

thetics, with substantial changes in the

treatment plan of the posterior region.

These restorations can be classified as

follows:

Additional overlay (Figs 30 to 35): This

is a partial or, more frequently, complete

coverage restoration performed without

any tooth preparation. It is indicated in

cases of anatomic restoration of teeth

with loss of tissue due to erosion/abrasion

or in cases of occlusal vertical dimension

increase. The gold standard material is

ceramic (lithium disilicate), although it is

also possible to use composite.

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Fig 33 Adhesive cementation of the all-indirect

additional restorations.

Fig 34 A detail of teeth 26 and 27 with an excel-

lent morphological functional esthetic integration.

Fig 35 The maxillary arch after the rehabilitation.

Fig 32 The teeth without any preparation before

the adhesive cementation.

Occlusal-veneer (or “table-top”): This

is a thin (1 to 1.2 mm) bonded posterior

occlusal partial-coverage preparation

with a non-retentive design. It is indicat-

ed, above all, in advance erosion of the

occlusal surface or in clinical restora-

tive cases where the vertical dimension

needs to be increased6,7 (Figs 36 to 43).

An in vitro fatigue study37,38 concluded

that CAD/CAM superthin (0.6 mm) com-

posite resin occlusal veneers had sig-

nificantly higher fatigue resistance when

compared to ceramic occlusal veneers.

Overlay-veneer (or “veneerlay”)

(Figs 44 to 49): This is used in the case

of a restoration that involves the oc-

clusal surface that extends to the entire

buccal surface due to either esthetic

or functional considerations. It is indi-

cated in teeth positioned in esthetic ar-

eas (typically maxillary premolars) with

significant loss of hard tissue, heavily

discolored, and resistant to bleaching.

The gold standard material is ceramic

(lithium disilicate).

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Figs 36 and 37 Maxillary and mandibular arches before treatment. There is a clear need to completely

rehabilitate the arches because of inadequate restorations, abrasions, wear, and tooth discoloration.

Fig 38 Diagnostic wax-up of the maxillary and

mandibular arches. Thereafter, a direct adhesive

mock-up will be performed in the mandibular arch,

increasing the vertical dimension.

Fig 39 First phase of rehabilitation of the mandib-

ular arch on the lateral-posterior side with occlusal

veneer of teeth 34, 35, 44, 45, and 46. Tooth 36 is a

metal-free crown on an implant.

Fig 40 Detail of minimally invasive preparations. Fig 41 The ultra-thin lithium disilicate pressed oc-

clusal veneer (IPS e.max Press) of quadrant 4 after

adhesive cementation.

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Fig 42 The mandibular arch after the complete

adhesive rehabilitation, with ceramic occlusal ve-

neer on all the posterior and anterior teeth. Two

lithium disilicate crowns on teeth 36 and 37.

Fig 43 The maxillary arch after complete ad-

hesive rehabilitation, with partial and full-pressed

ceramic restorations on the posterior and anterior

teeth.

Fig 44 Maxillary bicuspid with previous compos-

ite restoration and signs of occlusal wear.

Fig 45 Vestibular side with inadequate esthetic

integration.

Fig 46 Partial prepa-

ration with coverage of

occlusal and buccal as-

pect in insulated field.

Fig 47 Lithium disili-

cate pressed overlay ve-

neer (IPS e.max Press).

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Fig 48 Restoration after adhesive cementation

with esthetic restoration of the buccal appearance.

Fig 49 Restoration with morphological and func-

tional occlusal reconditioning.

Long-wrap overlay: This restoration in-

volves the complete occlusal surface. It

extends to either the buccal and/or pala-

tal-lingual axial walls, depending on hard

tissue loss and regardless of soft tissue

profile. It is indicated in teeth that require

complete cuspal coverage extended to

axial walls for the presence of extensive

carious lesions, abrasions, biocorrosions

or fractures involving the external sur-

faces. The material of choice is ceramic

(lithium disilicate), although composite

can be indicated only as a less-expen-

sive compromise (Figs 50 to 52).

Fig 50 Long-wrap overlay preparation according

-

cal reduction of the tooth after root canal treatment

and build-up is apparent.

Fig 51 Anatomical preparation of the occlusal

surface.

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Adhesive-crown49,50 (Figs 53 to 59):

This restoration completely covers the

tooth, with supragingival margins that

follow the contour of the marginal soft tis-

sue, and which is adhesively cemented

after rubber dam isolation. It is indicated

in teeth with a major loss of tissue requir-

ing a total preparation. The adhesive ap-

proach allows the clinician to be more

conservative on the poor residual dental

Fig 52 The indirect composite restoration after adhesive cementation with good esthetic, morphological,

and functional integration.

tissue and periodontal tissue than with a

conventional complete crown. With this

restoration, surgical crown lengthening

is usually avoidable because it is not

necessary to gain resistance and retain

form, which is fundamental when con-

ventional prosthetic restorations are per-

formed. The material of choice is lithium

disilicate.

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Fig 53 Maxillary bicuspid endodontically treated

with a significant loss of dental tissue.

Fig 54 Preprosthetic adhesive reconstruction

made of composite with a fiber post.

Fig 55 The buccal aspect shows minimum inter-

occlusal thickness that would require an apical po-

sitional flap in the case of a traditional crown.

Fig 56 Preparation for the adhesive crown. (a) Occlusal view. (b)margin allows for the insulation of the field with rubber dam.

a b

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Conclusions

Modern restorative dentistry is substan-

tially adhesive. The conservative spirit

should pervade all procedures. Preserv-

ing healthy tissue (not only dental, but

also pulpal and periodontal) has be-

come the priority. With this approach,

indirect adhesive restorations are indi-

cated in large cavities associated with

cuspal coverage with absent or reduced

amounts of cervical enamel.

The rationale of this study was to re-

vise cavity design concepts borrowed

from old patterns for non-adhesive res-

torations, which are outdated, not con-

servative, and unsuitable for adhesive

procedures. This new cavity design al-

lows for the following clinical advantag-

es:

Definition of a margin design which

acts to improve adhesion quality

through the optimization of the enam-

el cutting and the creation of a greater

surface of enamel provided.

Minimal dentin exposure, avoiding

wide shoulders, occlusal slots, and

wells.

Maximum preservation of healthy

residual tissue, adapting the cavity

design to adhesive cementation pro-

cedures with composite resins, and

improving the flow of excess material.

Optimization of the esthetic perfor-

mance, which allows for better blend-

ing in the transition zones.

The new principles of preparation dis-

cussed in this article can be applied ef-

fectively to all types of traditional adhe-

sive restorations (inlay, onlay, overlay),

and help to define a set of newly de-

veloped restorations (additional overlay,

Fig 57 Lithium disilicate pressed adhesive crown

(IPS e.max Press) on galvanized stone model.

Fig 58 Adhesive cementation with preheated

composite material.

Fig 59 cementation with good esthetic and functional in-

tegration.


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occlusal-veneer, overlay-veneer, long-

wrap overlay, and adhesive crown). The

different types of restorations constitute

a significant proportion of treatment

options available for the rehabilitation

of the posterior teeth, and allow us to

define a new line between conservative

and prosthetic treatments, in favor of a


Acknowledgments

Dr F. De Fulvio (Moricone, Roma, Italy) for his invalu-

able assistance in drafting the article; Dr N. Scotti

(TO, Italy) for the translation and review; the dental

technicians for their excellent work: A. Pozzi (PR,

Italy), F. Pozzi, A. Quintavalla (PR, Italy), and M.

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