Crown and post-free adhesive restorations for ...opment of the adhesive philosophy in dentistry and...

CLINICAL RESEARCH

154THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY

VOLUME 8 • NUMBER 2 • SUMMER 2013

Correspondence to: Giovanni Tommaso Rocca

Department of Cariology and Endodontics, School of Dentistry, 19 Rue, Barthélémy Menn, 1205 Geneva, Switzerland;

E-mail: [email protected]; Tel: 022.3794100; Fax: 022.3794102

Crown and post-free adhesive

restorations for endodontically

treated posterior teeth: from direct

composite to endocrowns

Giovanni Tommaso Rocca, DMD

Senior Assistant, Division of Cariology and Endodontology,

School of Dentistry, University of Geneva, Geneva, Switzerland

Ivo Krejci, Prof. DMD

Chairman, Division of Cariology and Endodontology,

School of Dentistry, University of Geneva, Geneva, Switzerland

ROCCA/KREJCI



Abstract

Coronal rehabilitation of endodontically

treated posterior teeth is still a controver-

sial issue. Although the classical crown

supported by radicular metal posts re-

mains widely spread in dentistry, its in-

vasiveness has been largely criticized.

New materials and therapeutic options

based entirely on adhesion are now-

adays available. They allow perform-

ing a more conservative, faster and less

expensive dental treatment. All clinical

cases presented in this paper are solved

by using these modern techniques, from

direct composite restorations to indirect

endocrowns.

(Eur J Esthet Dent 2013;8:154–177)



CLINICAL RESEARCH



Introduction

Endodontically treated teeth (ETT) are

more prone to fracture.1 One of the key

reasons for this increased weakness is

the lack of tooth substance following the

pathological process and endodontic

treatment of the tooth in question. This

biomechanical alteration inflicts a nega-

tive impact on the long-term prognosis

of the tooth.2,3 Therefore, when con-

sidering the restoration of devitalized

teeth, dental materials should be able

to replace the loss of tooth substance in

order to ensure mechanical and func-

tional properties, esthetics and coronal

seal.

Traditionally this function is fulfilled

by a porcelain fused to metal (PFM) or

a full-ceramic crown, which is usually

cemented onto a core fixed to the root

by an endodontic post. Although some

long-term retrospective studies have

demonstrated its good reliability,4,5 this

kind of approach may be invasive both

in the crown and in the root. In case of

failure, the invasive nature of such pro-

cedures often excludes the possibility of

a re-intervention due to the poor quantity

of the remaining dental tissues; in addi-

tion, it exposes the tooth to a higher risk

of irreversible fractures.

Moreover, the fabrication of a crown

may involve many technical steps

(crown lengthening, post cementation,

core fabrication and temporary crown),

which increase the time and cost of treat-

ment. All these intermediary stages may

also favor bacterial infiltration and cause

endodontic re-infection. However, in the

past, crowning of devitalized teeth was

considered a must to protect the remain-

ing tooth substance. Tooth-destructive

fricative elements such as prefabricat-

ed metallic posts have been widely and

wrongly suggested in presence of an ex-

tensive tissue loss, not only to retain the

crown but also to recover the stiffness of

the tooth. Contrary to this preconceived

idea, it is largely proved today that these

elements do not reinforce the tooth but

contribute to its weakness.6

During the last 30 years, the devel-

opment of the adhesive philosophy in

dentistry and the high bonding perfor-

mances achieved by modern adhesive

systems have gradually changed the

dogma “devitalized tooth = crowned

tooth” and many classical indications for

a crown restoration are nowadays ques-

tioned.7 Modern clinical procedures to

restore ETT are rather based on the prin-

ciples of the minimally invasive dentis-

try, which attempts to conserve sound

tissues. This kind of conservative den-

tistry is accomplished by using adhe-

sive techniques, as adhesion ensures

sufficient material retention without the

need of aggressive macroretentive tech-

niques. Consequently, restoration of de-

vitalized teeth follows in many cases the

same principles as the restoration of vi-

tal teeth.

The aim of this article is to show a

modern therapeutic approach based

entirely on adhesive dentistry. The fab-

rication of direct and indirect adhesive

restorations on ETT is illustrated in some

representative clinical cases. A new ra-

tionale is also presented to help the op-

erator in choosing the correct adhesive

restoration according to the tooth cav-

ity configuration and the tooth’s esthetic

needs.

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Treatment plan

The choice of the therapeutic option

when restoring a devitalized tooth is

based on several factors. Certain factors

such as the geometry of the tooth cavity,

the tooth localization in the mouth, as

well as esthetics, are essential in estab-

lishing objective and simple guidelines.

Others, like the presence of parafunc-

tions in the occlusal context, the age of

the tooth and its endodontic/periodontal

prognosis, and the financial aspects are

important factors but should be consid-

ered separately as special single cases.

Loss of substance (tooth cavity configuration)

The major changes in the biomechan-

ics of an ETT are caused by the loss

of tissue due to the previous pathology

(caries, fracture, cavity excavation), to

the endodontic treatment (access cav-

ity, root canal shaping) and to some

invasive restorative procedures (post

placement, crown fabrication).8 All

these factors may contribute to a con-

sistent removal of coronal and radicular

tissues, which enhances the weakness

and the risk of fracture of an EET. In the

coronal part of the tooth, a few partic-

ular cavity configurations seem to be

more at risk. Several in vitro studies9-12

show that the conservation of the mar-

ginal ridges is a fundamental factor in

limiting abnormal cuspal deflection and

breakdown. Thus, an occlusal (O) cav-

ity and a mesial-occlusal-distal (MOD)

cavity are on the opposite side of a hy-

pothetical safety scale (Fig 1). Further-

more, the loss of the parapulpal dentin

– the dentin above and near the pulp

chamber – as a natural consequence

of an endodontic treatment is another

major weakening factor.10,11 As a con-

sequence, the deepest MOD cavities

on an ETT should be considered as the

worst cavities in terms of fracture risk. In

those cases, scientific literature agrees

that a cuspal coverage of the tooth has

to be planned in order to avoid extreme

flexure of the cusps and balance the oc-

clusal forces (Figs 2a and 2b).

Fig 1 The risk of fracture of an endodontically treated tooth is directly related to the quantity of tissues

lost and to the specific cavity configuration.



CLINICAL RESEARCH

When considering sound coronal tis-

sues available for adhesion in a devi-

talized tooth, remaining walls must be

sound, free of fissures and at least 1 mm

wide to be considered as safe (Fig 3).

That estimation should be done during

the preliminary steps of the endodontic

phase when the cavity is first cleaned

and the pulpal tissue is removed. Fis-

sured and thin cavity walls should be

detected before the build-up of the pre-

endodontic composite resin reconstruc-

tion, as a part of this resin is often left in

place later as a base for the definitive

restoration.

The tooth type (molars vs premolars)

The anatomical and physiological dif-

ferences between molars and premo-

lars may be crucial when choosing the

therapeutic option. First, molars are

larger than premolars and they have a

larger pulp chamber. Therefore, they

have more surface available for adhe-

sive procedures than premolars. When

a considerable amount of tissue is lost,

this feature is of high importance. More-

over, molars and premolars are usually

submitted to a different set of loads. In a

normal occlusal context – class I molar,

canine lateral guidance, incisors anter-

ior guidance – posterior teeth (molars

and premolars) are more subjected to

axial forces while anterior teeth (canines

and incisors) are more exposed to shear

forces. Despite this ideal situation, more

often canine lateral guidance is replaced

by a group function where premolars

participate in lateral movements. There-

fore, premolars’ cusps are subjected

to a more complex set of forces that is

formed by either axial and shear loads

and that could be potentially harmful.

Thus, in most cases molars can be re-

stored by relying solely on adhesion while

premolars could ask for a post place-

ment in case of scarce residual tooth

structure. Practical guidelines derived

from clinical experience for the evalua-

tion of the remaining sound tissues and

indications for a post placement have

been mentioned previously.3,10

The esthetic factor

Esthetic needs of ETT are critical for the

cavity preparation and for the material

selection. Those needs are established

imperatively at the beginning of the first

appointment. The buccal visibility of the

treated tooth inside the “smile space”

(the virtual space between the upper and

lower lips during full smiling of the pa-

tient) implies high esthetic needs (Fig 4).

Whenever the restoration margins invade

this space, in case of cuspal coverage

for example, a homogeneous transition

between the restoration and the tooth

could present a hard esthetic challenge.

Three solutions are offered to the oper-

ator. First, buccal margins of the restor-

ation can be placed in the cervical third

of the crown, close to the gingival line

in order to place the transition in a hid-

den zone. This “crown-like” buccal mar-

gin yields appealing esthetic results but

is invasive in nature (Fig 5d). As a more

conservative alternative – but more chal-

lenging from an esthetic point of view –

buccal margins can be left in the middle

third of the crown, at a distance of 2 to

3 mm from the occlusion plane (Fig 5c).

In that case a large amount of enamel

and dentin is saved but the esthetic in-

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Fig 2a and 2b Ra-

tionale for the choice

of the proper thera-

peutic option for ETT.

It is important to un-

derline the schemat-

ic aspect of these

guidelines: thickness

of remaining walls,

dimension of the cav-

ity and above all the

occlusal context can

influence the thera-

peutic choice.

Fig 3 A long vertical fissure in the distal marginal

ridge is clearly visible after the preparation of this

3.6. This wall has to be included in the future res-

toration as it cannot be considered as safe. The

geometry of the cavity changes from MO to MOD.

Fig 4 The “smile space”. In some cases, poster-

ior teeth should be considered like anterior ones in

terms of esthetic needs.

cavity

Class I

Class II MO/OD

cuspal coverage

no*

* In safe occlusal context

suggested restoration

Direct composite

Direct compositeIndirect restoration

endocrown

endocrown

post+core +PFM

Class II MOD

premolars molars

cavity cuspal coveragesuggested restoration

yes

CLINICAL RESEARCH



tegration of the restoration is more chal-

lenging. An attractive possibility is to

place the visible margins in the incisal

third of the buccal cusp, at just 1.5 mm

from the occlusion (Fig 5b) conserving

the buccal cusp almost entirely. The indi-

cated option, although still experimental

and tested just only on vital teeth,11,12 is

very interesting as it combines minimal

invasive dentistry and esthetics. In the

case where a part of the buccal cusp is

envisioned to be left in place, conforming

to this type of configuration, and there is

evidence of dentin discolorations, an in-

ternal coronal bleaching could be indi-

cated before the placement of the final

restoration (Fig 10c).

Clinical cases

Class I (4-walls cavity)

In this cavity configuration, the EET pre-

sents a wide and deep occlusal cavity

inserted in 4 remaining walls. If these

walls are sound and thick enough, this

cavity is considered the safest in terms

of fracture risk. In a well known study

Reeh et al9 have measured a loss of

tooth stiffness of about 20% associ-

ated to an occlusal endodontic access

cavity, compared to a 63% for a MOD

endodontic cavity. Later, other labora-

tory tests10,11,13 have confirmed this

hypothesis. Few studies exist in litera-

ture describing the clinical effective-

ness of direct composite resin for Class

I cavities in EET. The scientific opinion

is generally positive towards this kind

of restoration even if the results of the

clinical trials are frequently confounded

either with other kind of cavities inside

the wider category of direct composite

resins13,14 or with other materials like

amalgams within the group of Direct

Restorations.15

The Class I case presented is an en-

dodontically treated maxillary first molar

(Figs 6a to 6c). Once the provisional res-

Fig 5 Guidelines for full occlusal coverage. Palatal and lingual cusps can be simply reduced by 2 to

3 mm with a butt-joint (a). On the contrary, for buccal cusps there are 3 options: (b) The ultra-conservative

buccal cusp coverage (1.5 mm); (c) The conventional buccal cusp coverage (2–3 mm); (d) The full buc-

cal cusp coverage.

palatal/ lingual cusp

buccal cusp

Min 2 mm

A

B

C

D

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Fig 6a Occlusal view of the Class I cavity on the

maxillary first molar. The cavity is cleaned and iso-

lated.

Fig 6b A hybrid composite resin is gradually in-

serted into the cavity. Each layer is light-cured for

at least 40 s.

Fig 6c Final view of the direct composite restor-

ation.

toration is removed, the cavity is isolated

with a rubber dam and adhesively treat-

ed with a self-etch or an etch-and-rinse

adhesive system (Table 1). Then, small

amounts of hybrid composite resin are

directly inserted in the cavity and polym-

erized. The aim is to fill the cavity and

limit the resin polymerization shrinkage.

The highest configuration factor (C fac-

tor) of this kind of cavity imposes that

strategy. To that purpose, the composite

resin is progressively stratified into the

cavity by applying 2 to 3 mm oblique in-

crements. Each layer is polymerized for

40 seconds with the LED lamp as close

to the surface of the resin as possible.

Then, the restoration is finished and pol-

ished with silicone points and fine abra-

sive disks. A final touch of polymerization

under glycerin gel avoids any oxygen-

inhibition layers. Finally, the rubber-dam

is removed and the occlusion checked,

and adjusted if necessary.

Class II MO/OD (3-wall cavity)

In this kind of 3-wall cavity configura-

tion, the mesial or distal remaining mar-

ginal ridge protects the tooth from cata-

strophic mesio-distal fractures. In the

past, several studies have shown the

protective role performed by a sound

and tight marginal “third wall”. Reeh et

al9 found that the loss of tooth stiffness

in these kinds of cavities is about 45%

compared to a 63% of an MOD cavity.

Panitvisai et al13 found that the bucco-

lingual cuspal movement in the 3 walls of

MO cavities is about 7.5 mm instead of

16.5 mm observed in 2-wall MOD cavi-

ties. These results was also confirmed

by Gonzalez-Lopez et al11 who showed

that removal of both marginal ridges in

CLINICAL RESEARCH



Table 1 Adhesive systems

Dentin

Self-etch Etch-and-System rinse System

Enamel Composite Silica-based Ceramic

Conditioning

Self-etching

primer

(10 sec and dry)

Ortophosphoric

acid

(10 sec)

Ortophos-

phoric acid

(40 sec)

Sandblasting

with Al3O2

(27 to 50 mm)

Hydrofluoric

acid (following

manufacturer

instructions)

Priming

Primer solution

(10 sec and

dry)

Organic silane

(60 sec and

dry)

Organic silane

(60 sec and

dry)

BondingBonding resin

(10 sec and dry)

Bonding resin

(10 sec and

dry)

Bonding resin

(10 sec and

dry)

Bonding resin

(10 sec and

dry)

Bonding resin

(10 sec and

dry)

devitalized premolars led to a dramatic

increase in cuspal deflection, above all

under extreme loads (from about 10 mm

for a MO cavity to 56 mm for a MOD

cavity under 100 N load and from about

14 mm to 114 mm respectively under

150 N load). Recently, Salameh et al16

found that MO cavities in endodonti-

cally treated molars restored by direct

composite resins demonstrate a fracture

resistance superior to MOD cavities,

with and without fiber posts. However,

in another similar study on devitalized

premolars, Sorrentino et al17 found no

differences in fracture strength between

3- and 2-wall cavities. An in vitro study18

has focused on the adequate thickness

of this remaining marginal ridge. Results

of this study prove that sound marginal

walls of a thickness superior to 1 mm in

devitalized premolars restored by direct

composite resins have fracture strength

similar to that of intact teeth.

The clinical relevance of all this labora-

tory research is that under the aforemen-

tioned conditions and in the absence of

parafunctional stresses, a full occlusal

coverage in this type of cavity configu-

ration can be avoided. Hence, the pres-

ervation of the lingual and buccal cusps

ensures a more conservative and es-

thetic approach. Furthermore, frequently

3-wall cavities without cuspal coverage

can be easily restored with composite

resins using a direct technique.

Direct technique Simple 3-wall cavities in ETT can be re-

stored by direct composite resins. The

case presented in this paper is a devi-

talized maxillary first molar with a medi-

um/large MO cavity (Figs 7a to 7e). The

presence of a thick and sound distal wall

allows for the entire conservation of the

buccal and palatal cups and avoids a

further loss of substance. A radiograph-

ic examination must always confirm the

clinical diagnosis (Fig 7b). From an es-

thetic point of view, the possibility to con-

serve the buccal wall almost entirely is

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Fig 7a Initial view of the endodontically treated

first molar. The cavity is cleaned and put under rub-

ber dam isolation. The application of a liquid light-

curing rubber dam in the interproximal space helps

to isolate the operatory field.

Fig 7b On the bite-wing radiograph, the thickness

of the remaining distal wall of the 2.6 is checked.

Fig 7c After the application of the adhesive sys-

tem, the restorative hybrid composite resin is strati-

fied into the cavity, starting from the interproximal

mesial wall in order to transform the Class II cavity

into a Class I cavity. The use of a transparent shade

to fill the pulp chamber in the first 2 mm facilitates

the detection of the root canals in case of endodon-

tic re-intervention.

Fig 7d Once removed the metal matrix the enam-

el composite layer can be sculpted easily.

a great advantage. Despite large cavity

dimensions, a direct composite resin is

chosen to restore this molar instead of

an indirect solution. This choice is above

all dictated by a simple clinical/practical

feasibility more than future restoration’s

dimensions. Once the adhesive system is

applied, composite resin is stratified into

the cavity by applying 2 to 3 mm oblique

increments, starting from the interproxi-

mal mesial wall in order to transform the

Class II cavity in a Class I cavity. Details

CLINICAL RESEARCH



concerning the technical procedures for

direct composite have been already de-

scribed previously for Class I (Fig 6).

Indirect techniqueIndirect restorations are a good alterna-

tive to direct composite resins in the case

of large 3 wall cavities, especially in situ-

ations when clinical feasibility becomes

too complex for a direct technique. Such

a case is illustrated in Figs 8a to 8o,

where a maxillary second premolar pre-

sents with a large occlusal-distal-palatal

cavity including sub-gingival distal mar-

gins. During the first appointment, the

indirect technique allows the relocation

of the intracrevicular margins, and the

ideal interproximal and occlusal anato-

my is achieved later with the lab-made

restoration.

Fig 7e Final view of the direct composite restoration.

By programming two appointments,

a conventional indirect composite

technique is thus accomplished. Dur-

ing the first appointment,19 the cavity

is cut under local anesthesia. Once the

cavity is properly isolated an adhesive

system is applied on whole dentin and

on the distal thin subgingival portions of

enamel margins and light cured. Next

a thin composite resin layer is applied

on dentin and light cured. The goal is

to fill the pulp chamber, cover all the

dentin and to arrive at an ideal geom-

etry of the cavity: correct taper, minimal

undercuts, cervical margins relocated

supragingivally and adequate interoc-

clusal space. For that purpose, a low

shrinking hybrid composite resin is

suitable. Finishing the enamel margins

with fine diamonds instruments is the

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last step before impression. The prep-

aration of a small pit in the middle of the

pulp chamber composite and/or flat

distal margins will help the positioning

of the restoration during luting (Fig 8d).

After the impressions, a soft compos-

ite resin temporary material (eg, Fer-

mit, IvoclarVivadent) is inserted into

the cavity and light cured without ce-

mentation. Then, the composite resin

workpiece is fabricated in-lab on a cast

model (Fig 8e). During the second clin-

ical session the workpiece is tried in the

mouth. The anatomy, esthetic integra-

tion, interproximal surface contact and

fit of the margins are verified. Next the

internal surface of the indirect compos-

ite resin restoration is adhesively treat-

ed and then left under light protection

(Table 1) (Figs 8f to 8h). The next step

is the adhesive treatment of the cavity

(Table 1) (Figs 8i to 8l). The procedure

is simplified by the presence of enamel

and composite resin only, as there is

no exposed dentin20. A conventional

photopolymerizable hybrid composite

resin is used as luting cement. Before

the insertion into the cavity, this com-

posite resin should be heated up to a

temperature of about 50°C to decrease

its viscosity. Immediately thereafter,

the restoration is inserted into the cav-

ity and is first forced in place manually

and then with the help of ultrasonic en-

ergy. The use of a metallic plugger is

contraindicated when the thickness of

the restoration is thin because it may

introduce fractures. Excess of luting

composite resin at the margins are re-

moved with a probe and interproximal

floss. A first light polymerization is per-

formed with a high power LED unit 5 s

per surface, which serves to fix the sur-

Fig 8a Palatal view of the upper second premolar

after removal of the provisional restoration. If cavity

margins are largely subgingival, a crown-lengthen-

ing procedure must be planned.

Fig 8c Composite build-up. Whole dentin and thin

subgingival enamel are systematically covered.

please

reduce

figure

legend

Fig 8b Placing rubber dam is mandatory to fa-

cilitate adhesive techniques. In case of subgingival

margins, the placement of a metallic matrix and in-

terproximal wedges will displace rubber dam from

deeper margins, making its application easier.

CLINICAL RESEARCH



Fig 8d Before impression enamel is finished. A

flat distal margin will help the positioning of the res-

toration during luting.

Fig 8f Adhesive preparation of the workpiece: the

inner surface is sandblasted with 27–50 microns

Al3O2 particles at a distance of about 5 mm.

Fig 8h Application of a hydrophobic light-curing

bonding resin. The restoration is then put under light

protection.

Fig 8e The indirect composite restoration on the

cast model.

Fig 8g The conditioned surface is successively

“primed’ with an organic silane.

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Fig 8i Adhesive preparation of the cavity. The

composite layer is sandblasted.

Fig 8j Orthophosphoric acid etching of enamel

margins.

Fig 8l A light-curing bonding resin is applied onto

the entire cavity surface and spread in a very thin

layer with a gentle air jet, without being pre-cured.

Fig 8k Application of silane coupling agent on

composite resin. The accidental application of si-

lane on conditioned enamel does not have any

negative effect on enamel adhesion.

Fig 8m The restoration is inserted into the cavity.

A restorative hybrid composite resin is used as lut-

ing cement.

Fig 8n Full polymerization is achieved by light

curing for at least 90 s per surface.

please

reduce

figure

legend

CLINICAL RESEARCH



Fig 8o The luted indirect composite resin restoration.

face of the luting composite resin. Then

full polymerization in contact with the

irradiated surface is achieved by light

curing for at least 90 s per surface. Any

composite resin excess is subsequent-

ly removed with fine diamonds and re-

polished with flexible discs or silicone

points with slight pressure. A layer of

glycerine gel is finally applied over the

entire surface of the restored tooth and

the luting composite resin is cured for

5 s per surface through this gel to elimi-

nate the oxygen inhibition layer on the

surface of the luting composite resin,

if still not polished and removed. Fi-

nally, the rubber dam is removed and

the occlusion is checked. Any abnor-

mal contact in occlusion and during

lateral movements on the restoration is

removed.

Class II MOD (2-wall cavity)

Covering all the cusps by at least 2 to

3 mm is mandatory when 2 or 1 walls

remain in the cavity of an ETT. As stated

before, large and deep MOD cavities

are placed in a hypothetical safety scale

at the “border line” (Fig 1) from which

the danger of severe failures increases

drastically.

Bonded restorations with full occlus-

al coverage or “overlays” are proved

to have a beneficial effect on fracture

strength of ETT compared to simple

MOD restorations.14,22,21 The main rea-

son is that bonded overlays show a

more homogeneous distribution of biting

forces during function. Also, they have

a better cavity configuration in terms of

C factor, which allows lower polymeriza-

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tion shrinkage stresses on marginal ad-

hesive interfaces. Moreover, some stud-

ies show a certain protective effect of

these restorations against irreversible

fractures.22 However, these results are

in contrast with other in vitro tests where

the occlusal coverage configuration

has no influence on fracture strength

of ETT.21,23 With regard to materials, in

some recent studies14,25 a certain em-

phasis has been made to the fact that

composite resin overlays, due to their

lower Young modulus display better per-

formances versus ceramic, absorbing

and minimizing internal stresses.

EndocrownsWithin all bonded indirect restorations,

“overlay restorations on ETT” or “endo-

crowns” represent a particular category.

Fig 9a The esthetic prominence of the devitalized

tooth – the maxillary first premolar – must be primar-

ily checked.

Fig 9c The provisional restoration and the mesio-

distal composite are removed.

Fig 9b Initial view of the treated tooth.

Fig 9d The cuspal coverage during cavity prep-

aration: the palatal cusp is firstly reduced with a

diamond-coated bur.

CLINICAL RESEARCH



Fig 9e The buccal cusp is reduced to 0.5 to 1 mm

over the gingival level (see also Fig 5d). An over-

gingival margin facilitates rubber dam application

during adhesive procedures.

Fig 9f The lab-made glass-ceramic endocrown

(IPS e.max Press, IvoclarVivadent).

Fig 9g Adhesive preparation of the ceramic res-

toration: the inner surface is conditioned with hy-

drofluoric acid following manufacturer instructions.

Then, acid is first aspired trough high speed aspira-

tion and restoration is abundantly rinsed with water

spray.

Fig 9h Complete cleaning of the conditioned sur-

face is achieved by a post-etching cleaning using

orthophosphoric acid with a brushing motion fol-

lowed by immersion in an ultrasonic bath of distilled

water for 5 min. Then restoration is gently dried with

compressed air.

By definition, endocrowns are partial

crowns made out of ceramic or com-

posite resin that are bonded by resin

cements to the devitalized tooth. They

offer a full occlusal coverage and they

take advantage of the pulp chamber

to increase the available adhesive sur-

face. Different materials can be used to

fabricate an endocrown feldsphatic and

glass-ceramic, hybrid composite resin

and the newest computer aided design/

computer aided manufacturing (CAD/

CAM) ceramic and composite resin

blocks. Scientific literature is still uncer-

tain about which material is best indi-

cated for such restorations. The authors

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Fig 9i A silane coupling agent is applied for 60

s and dried. A thin layer of bonding resin is subse-

quently applied over the silanized surface, without

being pre-cured. Note the typical shiny aspect of

the inner surface after the bonding resin application.

Fig 9j Adhesive preparation of the premolar cav-

ity is achieved following the same procedure de-

scribed from Figs 8i to 8l.

Fig 9k The light-curing luting composite is inserted into the cavity and spread. High viscosity of conven-

tional hybrid composites can be reduced by pre-heating them outside of the cavity in special ovens and

eventually applying ultrasonic energy directly into the composite luting layer.

CLINICAL RESEARCH



Fig 9l Restoration is initially pushed in place man-

ually and then completely seated with ultrasonic en-

ergy.

Fig 9m Buccal and occlusal view of the glass-

ceramic endocrown.

prefer micro-hybrid composite resins

– lab-made or in the form of CAD/CAM

blocks – due to their stress-absorbing

properties and their practical benefits

like the possibility to modify and repair

the surface easily.26 Reinforced glass-

ceramics (eg, IPS e.max Press and

CAD, Ivoclar, may be alternatives to this

concept.

Several in vitro studies have proven

the validity of bonded endocrowns for

molars and premolars7,26-28,30 however,

only few in vivo trials29,30 have been

conducted and they report a good clin-

ical performances for molars. However,

classical treatments like post, core and

crowns must be still kept in considera-

tion for severely damaged premolars,

until further clinical tests could prove

the possibility to restore them solely by

endocrowns.

The first case of endocrown present-

ed is a maxillary first premolar with es-

thetic needs (Figs 9a to 9m). Once re-

moved the provisional restoration and

cleaned the tooth, the deep and wide

MOD cavity configuration supports the

full occlusal coverage of this tooth. The

palatal cusp is simply reduced by 2 to

3 mm with a butt-margin (Fig 9d). From

an esthetic point of view, the buccal

margin is placed in the cervical third, 0.5

to 1 mm over the gingival level (Figs 9e

and 5d). The cavity is then isolated and

prepared for an indirect restoration fol-

lowing the same procedures described

before for the case of Fig 8. Regarding

materials, a lithium disilicate reinforced

glass-ceramic (IPS e.max Press, Ivoclar

Vivadent) is chosen in this case for es-

thetic reasons. It is important to note that

the cavity preparation during the first

appointment and the adhesive surface

treatment of the cavity during the luting

appointment follow the same principles

and procedures for both ceramic and

composite endocrowns. The only differ-

ence is the adhesive treatment of the in-

taglio surface of the workpiece (Table 1

and Figs 9f to 9i) during luting.

The second case of an endocrown

presented is a mandibular first molar

ROCCA/KREJCI



Fig 10a Initial view of the endodontic treated

mandibular first molar. Old and leaked composite

restoration is removed and an endodontic retreat-

ment is programmed.

Fig 10b Image of the wide MOD cavity during the

pre-endodontic composite build-up. The quantity

and quality of remaining sound tissues available for

the definitive restoration is often evaluated during

this preliminary phase.

Fig 10c After the endodontic retreatment and

before the definitive restoration, one/two internal

bleaching sessions can be performed.

with lower esthetic needs than the pre-

vious maxillary case (Figs 10a to 10g).

That allows a more conservative design

of the endocrown above all in the buc-

cal “esthetic” side, meaning that buccal

cusps like lingual ones can be reduced

just a few millimeters from occlusion

(Figs 10e and 5c). In general, reduc-

tions by at least 2 to 3 mm are recom-

Fig 10d The first molar some weeks after the

bleaching. The tooth is ready to be prepared for the

endocrown restoration.

mended for ceramic and composite

resin restorations. Before the prepar-

ation of the cavity for the endocrown,

one/two sessions of internal bleaching

(sodium perborate and distilled wa-

ter or 3% hydrogen peroxide) may be

planned, in order to reduce the heavy

dental dyschromia, which is clearly vis-

ible on the buccal side.

CLINICAL RESEARCH



Fig 10f The lab-made composite endocrown.

Fig 10e Details of the cavity preparation. In this

case both buccal and lingual cusps were simply

reduced by 2 to 3 mm (see also Fig 5c).

Fig 10g Final view of the restored molar.

The third case of an endocrown is a

maxillary second premolar with a large

cavity including the mesio-distal inter-

proximal walls and the palatal cusp

(Figs 11a to 11e).31 In this kind of large

MODP cavity on premolars, a full occlus-

al coverage is currently recommended.

Consequently, the buccal cusp is entire-

ly reduced and classical post, core and

crown are usually programmed. In that

specific case, a new and experimental

design of endocrown was indeed real-

ized in which the cuspal coverage was

obtained with a minimal invasive reduc-

tion of the thick and sound buccal cusp.

Some modern studies have recently

pointed out that composite resin resto-

rations show enough resistance, even in

a thin layer.16,17 Thus, the buccal cusp is

slightly reduced and restoration margins

are placed in the incisal third at a 1.5 mm

distance from the occlusal plane and

lateral contacts (Figs 11b and 5b). On

the contrary, the pre-endodontic com-

posite resin is abundantly reduced in

the palatal side as well in the interproxi-

mal regions. This “modified” restoration

design (Fig 11d) for endocrowns is par-

ticularly interesting as a good esthetic

can be achieved with a minimal invasive

intervention.

Conclusion

This article illustrates how the principles

of minimally invasive dentistry can be

applied not only to primary restorations,

but to the field of re-dentistry as well,

in particular on non-vital teeth. Weak-

ened endodontically treated posterior

teeth can be restored functionally and

esthetically by direct and indirect adhe-

ROCCA/KREJCI



Fig 11a Initial view of the maxillary second pre-

molar with a large MODP provisional composite res-

toration.

Fig 11c Details of the cavity. A big portion of the

pre-endodontic restoration is conserved. A special

care was put in all the preliminary adhesive proce-

dures to fabricate this resin composite. The fabrica-

tion of a central box into the pulp chamber compos-

ite is essential for a good stability of the restoration

during adhesive cementation.

Fig 11b The ultra conservative reduction of the

buccal cusp is checked in occlusion and during

lateral movements (see also Fig 5b).

Fig 11d Distal view of the lab-made composite

endocrown. Buccal (V) and palatal (P) cusps.

sive techniques, thus avoiding a further

sacrifice of sound tissues for fricative

and macroretentive elements. By rely-

ing on adhesion, radicular posts are no

longer necessary on devitalized molars,

and at the present moment it is difficult

to decide if posts are necessary on pre-

molars and front teeth. If yes, they may

only be considered in the case of ex-

treme coronal destruction, without hav-

ing clear scientific evidence on their

necessity and exact indication. If used,

adhesive posts in a minimally invasive

restorative concept do not represent a

macromechanically retentive element.

They serve much more as a glass fiber

V

P



CLINICAL RESEARCH

reinforcement of a short radicular inlay

that searches to increase adhesive sur-

face within the root canal to increase ad-

hesive retention. Finally, it is important to

note that accurate case selection and

rigorous execution of adhesive proce-

dures are essential for the accomplish-

ment of this full adhesive strategy.

Acknowledgments

The authors would like to thank Dr Nicolas Riz-

calla for the precious help in clinical procedures,

Dominique Vinci (www.vinci.ch), and Marcus Rou-

bain (LDC Lausanne) for the laboratory works and

Izabella Nerushay for the English revision.

Photos copyright

Photos 8a, 8b, and 8o with the coutesy of

Bouillaguet S, Rocca GT. Restaurations

coronaries et corono-radiculaires des

dents dépulpées (in: Simon S, Machtou

P, Pertot WJ (eds.). Endodontie. Paris:

Editions CdP, Wolters Kluwer France,

2012).

Photos 11a to 11f with the courtesy of

Rocca GT, Krejci I. Restaurations adhé-

sives pour dent dépulpée. L’alternative

au tout couronne. Réalités Cliniques

2011;25–31.

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Fig 11f Final view of the composite endocrown.



ROCCA/KREJCI

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