The decision-making process in interdisciplinary treatment ...

212 | The International Journal of Esthetic Dentistry | Volume 14 | Number 2 | Summer 2019

SCIENTIFIC SESSION

The decision-making process

in interdisciplinary treatment:

digital versus conventional approach.

A case presentation

Nikolaos Perakis, DDS

Private Practice, Bologna, Italy

Renato Cocconi, MD, DDS, MS

Director, Face Ortho Surgical Center, Parma, Italy

Correspondence to: Dr Nikolaos Perakis

Via Albertoni 4, 40138 Bologna, Italy; Tel: Landline +39 051 6360616, Mobile +39 347 6438148;

Email: [email protected]

PERAKIS/COCCONI

213The International Journal of Esthetic Dentistry | Volume 14 | Number 2 | Summer 2019 |

Abstract

The digital technology can be a GPS in designing a

multidisciplinary treatment that involves orthodontics

and restorative dentistry. A proper hierarchy of deci-

sions and responsibilities need to be defined. Form is

everything but position and size.

For this reason the orthodontist first needs to set up

the proper occlusion deciding the position and the

available size that will be necessary for the restorative

dentist to obtain the proper form with a minimally in-

vasive preparation.

This case report illustrates with a step-by-step ap-

proach all the clinical issues of the treatment, from

diagnosis to orthodontic guided position of Tads, ma-

terials of choice and laminate veneers realization

passing through all the interactions between the den-

tal team members explaining who does what and

when and proposing a clear hierarchy of decision. A

review of digital and classical possibilities for the real-

ization of laminate veneers is proposed with its pros

and cons.

(Int J Esthet Dent 2019;14:212–224)


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Introduction

The development of new technologies and restorative

techniques has led to significant improvement in pa-

tient treatment modalities and also to the specializa-

tion of dentists. A multidisciplinary approach is often

necessary in order to take advantage of such innova-

tions and improve clinical outcomes by reducing the

invasiveness of treatments. A minimally invasive ap-

proach should be preferred to more invasive tech-

niques; in fact, tooth structure preservation is of para-

mount importance in order to respect biology and

guarantee the best biomechanical situation for dental

restorations.1-4

Furthermore, it has been observed that dentin ex-

posure during teeth preparation for laminate veneers

can affect the long-term result.5,6 To optimize the re-

sults, all the team members should take part in defin-

ing the steps of the workflow. It is essential to establish

the role that each professional should play in the dif-

ferent treatment stages: each single phase should be

supervised by a team leader who makes decisions

with the support of the other team members.

A digital workflow helps the team members to in-

teract and verify each step without the need to actual-

ly see the patient.

The aim of this article is to describe our interdisci-

plinary workflow and to show how digital technolo-

gies can obtain very precise results and save time. The

article also aims to demonstrate how combining digi-

tal technologies with traditional laboratory procedures

allows for a wide range of options of currently avail-

able restorative ceramic materials.

Case presentation

The patient was a 27-year-old female with a missing

maxillary left lateral incisor and a small lateral on the

Fig 1 Extraoral examination: an asymmetrical dental arrangement

of maxillary teeth affects the patient’s smile.

Fig 2 Extraoral examination: a mild skeletal class II and a biretrusion

are present.

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other side, together with an impacted maxillary left ca-

nine. The patient’s main reason for seeking treatment

was to improve her dental esthetics and smile without

considering the option of orthognathic surgical inter-

vention (Fig 1). The extraoral examination showed a

mild skeletal class II with a biretrusion and a projected

long nose (Fig 2). The patient did not want any change

to her face.

Intraorally, the patient had significant crowding in

the mandible and an asymmetrical dental arrange-

ment in the maxillary anterior area due to a diminutive

maxillary right lateral incisor and two mobile primary

teeth still present in place of an agenetic maxillary left

lateral and an impacted maxillary left canine (Fig 3).

In order to select the best treatment strategy for

the patient, we needed to follow a specific sequence

in the decision-making process (Schema 1).

Establishing the correct tooth positions

The orthodontist had the responsibility of defining the

appropriate maxillary and mandibular incisors’ position

and inclination. This affects the final decision of open-

ing or closing spaces for maxillary laterals, considering

the space requirement in both arches.

We used a three-dimensional (3D) virtual rendering

to define the proper position of the anterior and pos-

terior occlusal segments (Fig 4). After setting the oc-

clusion, we predefined the available spaces for the

volumes of the anterior maxillary teeth to maximize

the esthetic outcome (Fig 5). At the beginning of the

Hierarchy of decision: position Hierarchy of decision: form

ORTHODONTIST

ORTHODONTIST

ORTHO + RESTORATIVE

RESTORATIVE + ORTHO

RESTORATIVE/LAB

RESTORATIVE/LAB

RESTORATIVE/LAB

RESTORATIVE + LAB TECHNICIAN

RESTORATIVE + LAB TECHNICIAN

1st step: Mandibular & maxillary incisors’ inclination

Extractions/anchorage

Curve of Spee/Wilson

2nd step: Class 1 occlusion

3rd step: Volumes available for restorations

4th step: Final position of teeth for restorative

Step I: Ideal maxillary central incisors’ volume/MIP

Step II: Ideal maxillary lateral incisors’ position & volume

Step III: Ideal maxillary canine position & volume/MIP

5th step: Analog/digital workflow

6th step: Minimally invasive preparation

Schema 1 Sequence in the decision-making process

Fig 3 Frontal view at the beginning of the orthodontic phase. Two

primary teeth in place of an agenetic left lateral incisor and

significant crowding in the mandible is present.

Fig 4 Digital setup of the expected tooth position at the end of the

orthodontic treatment.

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treatment, we wanted to visualize and approximately

define how to position these teeth at the end of the

orthodontic treatment so as to facilitate the minimally

invasive restorative procedures to be performed at a

later stage. The orthodontist was responsible for de-

ciding whether to extract the two mandibular first bi-

cuspids due to lack of space. As a result, we decided

to extract the diminutive right lateral incisor (12) and

the two maxillary left primary teeth (62 and 63), to

substitute the maxillary laterals with maxillary canines,

and the maxillary canines with maxillary first bicuspids.

Fig 5 Digital wax-up to evaluate tooth shapes according to the

new dental position.

Fig 6 Cone beam computed tomography (CBCT)-guided position

of palatal implants.

After space closure, the restorative dentist indicated

the final orthodontic position of these teeth to opti-

mize a maximal intercuspation position and to set the

space for minimally invasive laminate veneers.

A fully digital orthodontic approach was used for

the palatal implants positioning and to obtain an ade-

quate orthodontic supporting appliance. This was

used to support a provisional, to disclude the impact-

ed canine (23), to mesialize the canines and posterior

buccal segments, and to maintain the maxillary mid-

line position (Figs 6 and 7).

Interaction between position and tooth shape

As previously mentioned, when the tooth position was

almost achieved, the restorative dentist directed the

finishing orthodontic stage and defined the correct

tooth shape. This step was essential for a minimally

invasive approach with thin laminate veneers. At the

first clinical restorative check, the tooth positions were

very close to what had been defined at baseline in the

digital wax-up. Only a few modifications were required.

The positions of teeth 14 and 13 were correct, and

their axes were compatible with a minimal tooth prep-

aration approach.

The gingival margins of the central incisors had to

be aligned and their axes tilted. Tooth 23 had to be dis-

talized to give more room to the interdental papilla and

to better distribute the volume of the final restorations.

Tooth 24 had to be torqued and intruded to reduce the

invasiveness of tooth preparation (Figs 8 and 9).

Fig 7 Orthodontic supporting appliance anchored to palatal

implants.

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Fig 8 First restorative check: the axes of the anterior teeth should

be corrected and the gingival margins aligned.

Fig 9 The maxillary left canine should be distalized to give room to

the papilla.

Final tooth shape definition and communication with the patient

At the second restorative check, once the ideal dental

position had been achieved and the incisal margins of

teeth 13, 12, and 23 had been reshaped, the next stage

of treatment could be planned. Tooth 24 could not be

intruded more due to the root position with respect to

the cortical buccal bone (Fig 10). The major restorative

issue of this case was to transform the maxillary ca-

nines to lateral incisors, and the first bicuspids to ca-

nines, ending up with good esthetics and a functional

canine guidance.7

Overall, there were three clinical possibilities for

evaluating the final shape of the anterior teeth:

■ The first possibility was completely digital, with a

digital smile design and virtual wax-up, as was done

Fig 10 Frontal view at the end of the orthodontic treatment. Two

maxillary canines are positioned in place of the lateral incisors, and

two premolars in place of the canines.

Fig 11 Composite mock-up performed directly in the patient’s

mouth.

at the beginning of treatment. This digital simula-

tion would then need to be tested in the patient’s

mouth before tooth preparation. A mock-up would

then need to be prepared in a second appoint-

ment, once the new shape of the anterior teeth

had been accepted by the patient.8,9

■ The second possibility was to send a series of ex-

planatory notes to the laboratory for a classical

wax-up, and from this fabricate a mock-up. Both

these possibilities do not allow the clinician to eval-

uate all the esthetic and functional parameters

from the beginning. This can only be done after the

realization of the mock-up.

■ The third possibility was a composite mock-up car-

ried out directly in the patient’s mouth (Fig 11).

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The final option was chosen because it involved the

patient in the process of improving her smile. The

composite was applied without adhesive and was

polymerized for 2 to 3 s, so that it was easy to remove

it at the end of the consultation. This rapid simulation

allowed the clinician not only to evaluate esthetics,10

phonetics,11 and function (guidance, overbite, overjet,

relationship to lips and tongue), but also to get imme-

diate feedback from the patient, and to make any re-

quired changes and adjustments (Fig 12). Once the

shape had been approved, some simple photos, an

impression, and a facebow registration for the spatial

orientation of the casts were taken. This 3D and func-

tional information could be transferred to the labora-

tory for the wax-up, with the aim of improving and

refining what was constructed in the mouth. In this

case, the wax-up would be performed using the trad-

itional technique, and the technician was able to man-

age the esthetic details with greater ease. At the third

restorative appointment, a silicone index of the fully

additive wax-up was prepared (Fig 13), and a resin

mock-up was pressed onto the teeth to enable the

patient to see the new appearance of her smile (Fig 14).

Minimally invasive tooth preparation

The mock-up was also used as a guide for dental re-

duction12 (Fig 15). The teeth were prepared in the most

conservative way, allowing for the maximum preser-

vation of enamel (Fig 16) and an adequate thickness of

Fig 12 The patient’s smile improved after the composite mock-up

realization.

Fig 13 Silicone index of the fully additive wax-up.

Fig 14 Intraoral view of the mock-up: esthetics, phonetics, and dynamics are carefully evaluated.

PERAKIS/COCCONI


the ceramic veneers (Fig 17). After the teeth had been

prepared, an impression was taken.

Eight ceramic laminate veneers were needed to

improve the patient’s smile.

Provisionals were fabricated using the same sili-

cone index that had already been used to place the

mock-up, so that the occlusal design could be dupli-

cated and the patient could retain the same level of

comfort. Provisional restorations could be pressed

and cemented simultaneously using the spot-etch

technique.13 This procedure allowed the teeth to be

stabilized during the provisional phase.

Laminate veneers realization: classical versus digital approach

All laboratory steps have been documented in a paral-

lel sequence in order to describe and compare the

classical and digital approaches. The materials used

most frequently to fabricate porcelain veneers are

feldspathic ceramics baked on refractory dies and

heat-pressed lithium disilicate ceramics. Both tech-

niques need a physical cast to be realized. Computer-

aided design/computer-aided manufacturing (CAD/

CAM) procedures can also be used with these mater-

ials. Nevertheless, a physical cast is always necessary

to finish the ceramic as well as for final checks before

delivery.

In the present clinical case, eight feldspathic ce-

ramic laminate veneers (Noritake EX-3; Kuraray Norita-

ke Dental) were used to restore the patient’s smile.

Fig 15 The mock-up can be used as a guide for a minimally

invasive tooth preparation.

Fig 16 Final preparations. Due to the attentive tooth structure

reduction, no dentin is exposed and the margins are placed in a

junta-gingival position.

Fig 17 A detail of the final feldspathic ceramic veneers.

The classical workflow started from a definitive

impression recorded using a polyvinylsiloxane (PVS)

material (Express; 3M ESPE). This impression was

poured twice in the laboratory to obtain a working

cast and a solid cast (Quadro Rock; Picodent) (Fig 18).

The working cast was mounted in an articulator and

its stone dies duplicated in a refractory material to

fabricate the feldspathic ceramic laminate veneers. A

purely digital workflow is not available at present, as

the absence of a physical cast limits the material

choice to CAD/CAM monolithic ceramics and does

not allow for the checking of the final prosthesis be-

fore delivery. For this reason, we followed a partially

digital workflow that benefits from the advantages of

digital technology without having to abandon those

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Fig 18 Classical workflow: a master cast and a solid cast were obtained from a polyvinylsiloxane impression of the maxillary arch. The stone

dies were duplicated in refractory material and inserted in the alveolar cast.

MASTER CAST SOLID CAST REFRACTORY DIES

Fig 19 Digital workflow: an intraoral scan of the maxilla was taken. The STL file was then processed through model-builder software to

fabricate physical resin-printed casts.

STL FILE MODEL BUILDER

Fig 20 Digital workflow: the resin dies were duplicated in refractory material.

PERAKIS/COCCONI


clinical and laboratory procedures that until now

have obtained the best esthetic results. The STL file

derived from the intraoral scanning of the prepared

teeth (Trios; 3Shape) had been processed by the

technician using model-builder software (Fig 19).

Digital master casts can be obtained either by mill-

ing14 or 3D printing.15 In this clinical case, a precise

physical cast was obtained using two different,

high-quality 3D printers (Stratasys Object Eden 500

for the alveolar cast; DWS DigitalWax 028Jplus Jew-

elry for the removable dies). The first printer uses a

PolyJet technology, where small drops of a photopo-

lymerizing resin are deposed on a work tray and im-

mediately cured by UV light. Layers are 12-μ thin, al-

lowing the casts to be very precise.16 The second

printer uses stereolithography (SLA) technology. A

building platform moves vertically into a bath of liquid

resin that is cured by a UV laser. The laser beam is

very thin, allowing one to obtain a very smooth sur-

face, with an accuracy of 10��μ.16

The resin dies were then duplicated in refractory

material and inserted in the alveolar cast (Fig 20). In

this way, the dental technician could layer the feld-

spathic ceramic directly on the physical cast (Fig 21).

Once layered and finished on the resin and stone

master casts, the laminate veneers were respectively

checked on the stone solid cast (Fig 22) and on the

3D-printed cast (Fig 23).

Final control and adhesive cementation

Before the final luting steps, the laminate veneers were

evaluated in the patient’s mouth: a homogeneous and

thin layer of Fit Checker (GC) material was used. The

marginal precision was clinically assessed using 5x

magnification loupes and a sharp probe. The quality of

the interproximal contact area was verified with thin

dental floss. Both digital and classical workflows end-

ed up with precise laminate veneers. No adjustments

were necessary, and, clinically speaking, no difference

in precision was found.

Regarding the treatment of the restorations, feld-

spathic ceramic was etched with 9% hydrofluoric acid

for 120 s, after which the restorations were rinsed and

then placed in an ultrasound bath with alcohol for

3 min to completely eliminate etching debris.17 A thin

Fig 21 The feldspathic ceramic was layered on the refractory dies.

Fig 22 Classical workflow: the ceramic laminate veneers were

checked on the solid cast.

Fig 23 Digital workflow: the ceramic laminate veneers were

checked on the 3D-printed cast.

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layer of a silane (Monobond Plus; Ivoclar Vivadent)

was then applied and left in place for 60 s.

A light-curing resin cement (Variolink Esthetic; Ivo-

clar Vivadent) with its adhesive system (Adhese Univer-

sal; Ivoclar Vivadent) was used to bond the veneers.

The resin cement excesses were carefully removed,

and each surface was light cured for 60 s using a LED

curing unit (Elipar S10; 3M ESPE). All margins were

then covered with a glycerin gel and light cured for a

further 20 s.

The rubber dam was then removed and the occlu-

sion finally checked.

After 1 week (Fig 24), and again after 1 year (Fig 25),

the restorations appeared very well integrated. The pa-

tient was satisfied with the esthetics and function.

Discussion

In interdisciplinary cases, the exact control of the clin-

ical steps is of paramount importance. For this reason,

the treatment planning and sequence should be care-

fully assessed, and one should define when and how

the dental team should intervene with clinical checks

and suggestions. Modern digital technology allows

one to visualize the final tooth position and form as

well as standardize and plan all these steps. This can

help the communication between the members of

the team and with the patient. It can also reduce time

and redundant steps. Only two clinical checks by the

restorative dentist were necessary during the ortho-

dontic phase.

The fully digital positioning of orthodontic palatal

implants and supporting structures helped greatly to

achieve the final orthodontic position, and for patient

communication and cooperation.

The finishing orthodontic stage aimed to produce

the small changes that the restorative dentist needed

so as to maximize the esthetic outcome with a mini-

mally invasive procedure.

A fully digital restorative workflow implies the use

of face scanners, optical impressions, and virtual

articulators in which the patient’s movements are

recorded during function. Unfortunately, it is not

easy to utilize this solution because most digital

inter faces are not available at present, and these

tools are not linked in one integrated digital work-

flow.18 The absence of a physical cast limits the

choice of material to monolithic ceramics only when

realized with CAD/CAM technology. There is also no

possibility of checking and finishing the prosthesis

before fitting, which implies long and complicated

clinical checks before cementation, especially in dif-

ficult cases.

Therefore, when choosing the restorative strategy,

the following factors need to be taken into consider-

ation:

1. The most-used materials for porcelain veneers are

feldspathic and lithium disilicate ceramic.

2. These materials can be produced following the

classical techniques (baked-on refractory dies and

heat pressed, respectively) as well as with the digi-

tal method using CAD/CAM technology.

Fig 24 Intraoral view of the final restorations. Fig 25 Intraoral view of the restorations at the 1-year follow-up.

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3. A precise physical cast is necessary to layer and

finish the ceramic laminate veneers as well as to

control the precision and quality of the final restor-

ations.

Starting from these requirements, one can examine

the possible treatment options. The completely ana-

log workflow has been used in prosthetics for decades

and allows for good clinical results. Nevertheless, nu-

merous laboratory steps can be reduced and im-

proved upon using digital technologies.19 The mixed

workflow proposed in this article allows one to take

the most from current digital possibilities and obtain a

high standard of work.

The direct intraoral scanning of the prepared teeth

has several advantages. The impression process is

more pleasant for the patient and avoids the impreci-

sion associated with the use of classical clinical and

laboratory materials (impression materials and stone

plaster). The quality of the impression can be immedi-

ately checked at high magnification on a monitor.

The space available with respect to the opposing

teeth can be easily verified. The STL file of such a dig-

ital impression can be reutilized by the laboratory at

any time, which seems to be more accurate than an

impression obtained by the laboratory scanning of

the stone casts20,21 when a CAM method is chosen.

Furthermore, digital impressions allow one to obtain

precise 3D-printed physical casts that can be mount-

ed in an articulator to manage both static and dynam-

ic occlusion, and can be used to produce laminate

veneers.

Conclusion

New digital technologies have significantly improved

patient treatment modalities, especially in interdisci-

plinary cases. A digital workflow helps the team mem-

bers to plan the clinical case, to interact during the

treatment, and to verify every clinical step effectively.

Nevertheless, a fully digital approach in the restorative

phase is not available at present. Combining digital

technologies and traditional laboratory procedures

may be the solution for maintaining a wide range of

options of currently available restorative materials.

Acknowledgments

We express our gratitude to Mr Gianluca Dallatana and

Mr Giuseppe Mignani for their precious collaboration,

and Dr Francesca Zicari for her help with editing the

manuscript.

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