CAM mock-ups

CLINICAL RESEARCH

Advanced smile diagnostics using CAD/CAM mock-ups Manuel Sancho-Puchades, DDS Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich

Vincent Fehmer, MDT Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich Department of Oral and Functional Rehabilitation, University of Geneva

Irena Sailer, Prof Dr med dent Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich Department of Oral and Functional Rehabilitation, University of Geneva

Correspondence to: Manual Sancho-Puchades, DDS Plattenstrasse 11, CH 8032 Zurich, Switzerland; E-mail: [email protected]

2 THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY VOLUME 10 • NUMBER 3 • AUTUMN 2015

SANCHO-PUCHADES ET AL

Abstract

autopolymerizing resin to obtain the pa-

Diagnostics are essential for predict-

procedure only produces a single ver-

able restorative dentistry. Both patient

sion of the possible treatment outcome,

and clinician must agree on a treatment

which can be unsatisfactory for both the

goal before the final restorations are de-

patient and the restorative team. Con-

livered to avoid future disappointments.

temporary digital technologies may pro-

However, fully understanding the pa-

vide advantageous features to aid in this

tient’s desires is difficult. A useful tool to

diagnostic treatment step. This article

overcome this problem is the diagnostic

reviews opportunities digital technolo-

wax-up and mock-up. A potential treat-

gies offer in the diagnostic phase, and

ment outcome is modeled in wax prior

presents clinical cases to illustrate the

to treatment and transferred into the pa-

procedures.

tient’s mouth using silicon indexes and

(Int J Esthet Dent 2015;10:XXX–XXX)

tient’s approval. Yet, this time-consuming


CLINICAL RESEARCH

Introduction

of reconstructive materials. A detailed esthetic analysis is necessary to im-

Patients asking for an esthetic improve-

prove the understanding of the patient’s

ment of their smile often have a desired

needs.5 However, considering the com-

goal in mind. The image of this dreamed

plex and subjective nature of esthetics,

appearance can vary greatly between

an objective materialization of all these

individuals, which makes the develop-

parameters is indispensable to ensur-

ment of a treatment goal challenging

ing that all points of view have been cor-

for the restorative team. It is the task of

rectly interpreted.1,3

the team comprising the dental techni-

A diagnostic wax-up is a useful tool to

cian, dentist, and patient to determine

achieve the goal of an objective material-

the desired outcome before the restora-

ization.3,6,7 It improves the communica-

tive treatment is performed. This diag-

tion between patient, clinician, and tech-

nostic phase, which aims to understand

nician, and gives a three-dimensional

the patient’s needs and to agree on the

representation of the tentative treatment

appearance of the final restoration, is

outcome.1,3,8 Usually, the dental techni-

key to obtaining satisfactory results in

cian models a possible dental configu-

comprehensive restorative dentistry.1-4

ration in wax using as references clinical

Moreover, foreseeing the final outcome

photographs and anatomical landmarks

allows for the early identification of spe-

on the diagnostic cast (existing occlusal

cific complementary treatments, such

plane and length and position of the re-

as crown lengthening procedures or or-

maining teeth). This process requires a

thodontic movements. It also guides the

significant amount of time and energy,

tooth preparations, since the restorative

since the technician must integrate all

space needed can be accurately as-

the esthetic guidelines and adapt them

sessed with the help of silicon keys.

to each individual case. The wax-up is

The diagnostic outcome can be as-

later tried in the patient’s mouth using

sessed at three time points. The first

silicone matrices and autopolymeriz-

and ideal time point is before any inva-

able resin to evaluate its integration into

sive treatment is performed. Once the

the patient’s smile and face, on what is

patient has entered the dental office in

called a diagnostic mock-up.1

pursuit of assistance, and a thorough

However, this procedure proves to be

medical and dental anamnesis and

impossible in certain clinical situations.

examination has been performed, a di-

It will only be effective when an addi-

agnosis must be executed. The restora-

tive reconstructive attempt is intended.

tive team will gather all the information

In other words, since the mock-up lies

registered at the first appointment and

over the unprepared teeth, only con-

will start the intellectual process of di-

tours placed more buccally, or larger

agnosing periodontal, endodontic, cari-

volumes, will be feasible. In cases where

ologic or functional pathologies. Addi-

subtractive procedures are necessary,

tionally, other equally relevant issues

the intraoral transfer of the wax-up will

have to be identified, such as the pa-

need to be performed in a later treat-

tient’s esthetic concerns and the choice

ment stage.



The provisional phase represents the

As previously mentioned, significant

second time point at which the esthetic

efforts are made to identify and mimic

and functional outcome of the prospec-

the desired esthetic outcome before

tive reconstruction can be evaluated.

the technician begins producing the

Eggshell indirect provisionals are pre-

final restoration. Despite the time and

ferred when a new smile configuration

energy invested to come up with a di-

is

intended.9

Patients who do not have

agnostic draft, the obtained result may

sufficient restorations or whose dental

neither match the patient’s physiognomy

appearance is unsatisfactory profit sig-

or personality nor represent the desired

nificantly from this provisionalization ap-

result expected by the patient and the

proach, since the esthetic improvement

restorative team. In these cases, small

is perceived immediately after the initial

changes can be attempted to modify

teeth preparation.

this initial draft. However, the range of

The third and last time point to de-

modifications is limited, and often a new

termine the desired restoration design

diagnostic version is necessary. The in-

corresponds with the wax-up try-in. Af-

ability to achieve the expected esthetic

ter the final impression is performed,

result with a try-in leads to patient dis-

and before the framework is produced,

satisfaction and, worse, the frustration

a new tentative configuration is made

of the restorative team, and involves in-

over the prepared abutments on the fi-

creased time and economic expenses,

nal cast. This step takes into account

since it means further diagnostic steps

the patient’s and restorative team’s

are necessary.

previ-

New computerized technology pro-

ous two diagnostic steps (diagnostic

cedures may be helpful to overcome

mock-up and provisional phase). Us-

these limitations. Computer technology

ing tooth-colored wax, the technician

is increasingly transforming the way

produces a wax try-in that will simulate

dentistry is being performed. Comput-

the color and contour of the final res-

er assisted design/computer assisted

toration. When the case involves eden-

manufacturing (CAD/CAM) processes

tulous spans or multiple units, the wax

are transforming what were previously

structure can require a metal or resin

manual tasks into easier, faster, cheaper,

framework to improve its strength. An

and more predictable mechanized meth-

advantage of this diagnostic maneuver

ods.10 Current industrial product devel-

lies in the plasticity of the wax, which

opment would be impossible without

allows immediate modifications of pos-

CAD technologies. Today, no engineer

sible imperfections discussed during

would consider designing a prototype by

the try-in appointment. Once the pa-

layering or carving a structure manually;

tient and restorative team have agreed

instead, a virtual environment is used,

on the optimum restorative outline, the

where different versions can be tried-in

wax try-in will be used as a reference

without significantly increasing the time

to determine the shape and thickness

invested and with no impact on the costs

of the framework and the veneering of

involved. Carving shapes manually has

the final reconstruction.

evolved into designing volumes virtually

impression

derived

from

the


CLINICAL RESEARCH

by means of dedicated software. In re-

Until now, subtractive CAM process-

storative dentistry, the wax and modeling

es have dominated dental manufactur-

are evolving into software and mouse-

ing routines. Restorations are obtained

clicks. The restorative team can profit

by trimming a solid block of material in-

from virtual libraries from where differ-

to the desired 3D object by means of a

ent tooth morphologies can be selected

computer-controlled milling machine.13

(Exocad, 3Shape, Dental Wings, Siro-

However, these procedures present sev-

na). These software tools offer numer-

eral shortcomings, such as the waste

ous different tooth shapes categorized

of considerable amounts of material,

according to parameters such as size,

the impossibility of creating geometries

patient’s age or phenotype. Moreover,

that lie below the milling bur diameter,

real teeth can be used as a reference

and the impossibility of mass produc-

to generate tooth morphology propos-

ing components.10,14 These restrictions

als.11 These standard shapes can later

can be overcome by the introduction of

be modified and adapted to individual

additive processing routes, such as lay-

patient situations. Working time is sub-

ered fabrication.15 An example of these

stantially reduced by eliminating the

technologies is 3D printers, which allow

mechanical handwork needed for con-

for the manufacturing of several objects

ventional waxing techniques. This allows

at the same time in a precise and cost-

the technician to focus solely on shapes

efficient manner. These 3D printers work

and tooth arrangements. Furthermore,

by jetting photopolymerizable materials

certain software allows for the integration

in ultrathin layers. Each layer is cured

of photorealistic three-dimensional (3D)

by ultraviolet light immediately after it

reconstructions of the patient’s face into

is deposited, producing fully cured ob-

The face is

jects.16 The dual jetting printing proced-

integrated by means of two-dimensional

ure requires two materials: a hard fun-

(2D) digital photographs projected onto

damental material and a gel-like support

a 3D virtual skull or by means of 3D facial

material. The support material is neces-

scanners. This allows for virtual smile de-

sary to sustain complex geometries of

sign, taking into consideration important

the fundamental material during fabri-

facial reference planes such as midline

cation and is easily removed by water

verticality, smile line, or the true horizon-

jetting after printing. Micron-accurate

tal plane. A further benefit is the possibil-

shapes can be printed in different com-

ity of rapidly modifying an initial design

binations of photopolymers, producing

version in order to effortlessly try in oth-

materials with specific mechanical and

er tooth arrangements. This grants the

visual properties. Products with different

technician freedom to generate multiple

levels of strength, rigidity, color, trans-

versions of the future restoration in an

parency, heat resistance or texture can

efficient manner. Being able to offer dif-

be obtained. This production modality

ferent versions at a single appointment

has widened the indication spectrum of

streamlines the diagnostic phase and

restorative computer-assisted dentistry.

potentially better fulfills the wishes of the

The aim of this article is to illustrate the

most demanding patients and clinicians.

benefits a CAD/CAM workflow provides

the virtual design

software.12



Fig 2 Volumetric information obtained by direct intraoral optical scanning.

Fig 1 Conventional workflow vs digital diagnostic

Fig 3 Plaster model being digitalized using a la-

workflow. A time progress bar is depicted under

boratory optical scanner.

each treatment step to show the relative time/effort needed for the completion of each step.

to the diagnostic processes during a

conventional esthetic diagnostic proto-

comprehensive restorative treatment. A

col. The anatomical data acquisition of

computer-assisted diagnostic treatment

the patient’s jaws can be obtained either

sequence will be described in detail and

by directly capturing the volumetric infor-

clinical examples given to illustrate the

mation using intraoral optical scanners

possible outcome that can be obtained.

or by digitalizing a plaster model using a laboratory optical scanner (Figs 2 and 3).17 The .STL data generated is trans-

CAD/CAM mock-up workflow

ferred into a software package that allows

Figure 1 illustrates the different treat-

cific tooth shape set is chosen from the

ment steps and estimated time invest-

virtual library. The projected tooth forms

ment needed to carry out a digital and a

are manually arranged by the dental

dental restoration design. After selecting the abutment teeth to reconstruct, a spe-


CLINICAL RESEARCH

technician onto the dental arch (Fig 4). Variations on the mesiodistal, buccooral, and occlusogingival dimensions, as well as tooth axis or tooth composition can easily be performed with the design software. Once a first version has been completed and saved on the computer, new versions can be efficiently created with a couple of clicks. For example, by simply dragging a virtual point, a standard tooth arrangement can easily be individualized by intruding or rotating teeth. The chosen blueprints, saved as .STL files, are then exported to a 3D printer that will layer the restorations (Fig 5). Nowadays, biocompatible photopolymers are available to produce rigid tooth-colored restorations. However, even though they are biocompatible, manufacturers recommend the limitation of mucosal membrane contact to 24 hours (see http:// www.stratasys.com/materials/polyjet/ bio-compatible). Consequently, the material is suitable to produce diagnostic mock-ups but not to manufacture proviFig 4 Virtual design of prospective reconstruction

sionals. The ease, speed, and reduced

using digital design software.

costs derived from this diagnostic workflow, in conjunction with the accuracy of the mock-up, make the procedure highly efficient and recommendable.

Fig 5 3D printer simultaneously producing different mock-up versions of a clinical case. Virtual printing tray, where the different .STL versions are arranged before printing (left). Printer simultaneously producing multiple resin blueprints (right).



Fig 6a Preoperative photographs of the patient.

The three clinical cases that follow il-

proved inconspicuous (vital teeth with no

lustrate the previously described pro-

periodontal pathology and satisfactory

cedures.

crowns); however, further assessments were necessary to obtain an esthetic diagnosis. A diagnostic wax-up was fabri-

Clinical cases

cated over a duplicate of the initial study

Case 1

struction was intended to be shorter than

model. Since the prospective reconthe current crowns, a direct preoperative

A 35-year-old female patient attended

mock-up was unfeasible. Based on the

the Clinic for Fixed and Removable

wax-up, eggshell provisionals were fab-

Prosthodontics and Dental Material Sci-

ricated and intraorally relined after the

ence of the University of Zurich dissat-

old restorations had been removed. The

isfied with her restorations on teeth 11

patient was satisfied with the length of her

and 21. Her main complaints were the

new restorations but did not like the teeth

unsatisfactory interincisal diastema and

shapes. Therefore, further diagnostic

the excessive length of both central inci-

maneuvers were needed before the final

sors (Fig 6a). The biological examination

restoration was initiated. Since a diag-


CLINICAL RESEARCH

Fig 6c Printed mock-up versions being tried in on the patient.

Fig 6b Versions of possible treatment out-

Fig 6d Preoperative view, chosen mock-up, and final

come: rounded, square, and butterfly shapes.

restoration.

Fig 6e Preoperative view, different mock-ups, and final restoration.



nostic wax try-in over the final prepared

mock-ups were tried in, and the patient

abutments was needed, a computer-as-

and restorative team could evaluate and

sisted workflow was chosen to offer the

compare the result on the patient’s den-

patient different teeth shapes and ar-

tal and facial appearance (Fig 6c). It was

rangements. After the final preparation of

agreed that the rounded version best

the abutments was performed, a digital

matched the patient’s physiognomy and

impression was taken with an intraoral

character, and was therefore used by the

scanner (iTero, Align Technology). The

technician as a reference for the final res-

.STL data generated was transferred to

toration (Figs 6d and 6e).

virtual design software (Exocad, Exocad) and three versions of the possible treatment outcome were designed: rounded,

Case 2

square, and butterfly shaped arrange-

A 52-year-old male patient attended the

ments (Fig 6b). The three .STL files were

Clinic for Fixed and Removable Pros-

sent to a 3D printer (Objet Eden260V,

thodontics and Dental Material Science

Stratasys), which produced the try-ins in

of the University of Zurich asking for a

an A3 colored resin (production time: 28

comprehensive rehabilitation of his de-

min) (PolyJet MED610, Stratasys). The

teriorated dentition (Fig 7a). His main



CLINICAL RESEARCH

Fig 7b Versions of possible treatment outcome.

concerns were to recover masticatory

final reconstruction was designed, a di-

function and to improve the appearance

agnostic try-in appointment was sched-

of his smile. After a thorough anamnesis

uled. The conventional master models

and exploration, the biologic patholo-

were optically scanned (IScan D104,

gies and esthetic flaws were identified.

Imetric), and three versions of the pos-

However, the diagnosis of the ideal con-

sible maxillary reconstructions were pro-

tour of the prospective reconstruction

jected utilizing virtual design software

needed further investigation. A wax-up

(Exocad). These three versions were

was fabricated and tried in as a direct

then printed in A3 colored resin (PolyJet

mock-up over the patient’s teeth. Likes

MED610) using a 3D printer (Objet Eden

and dislikes were analyzed in conjunc-

260V) (production time: 58 min) (Fig 7b).

tion with the patient, and the corre-

The digitally generated mock-ups were

sponding modifications were made to

tried-in and critically evaluated by the

the diagnostic wax-up. Based on these

patient and the restorative team (Figs 7c

corrections, eggshell provisionals were

and 7d). It was agreed that the version

made. These restorations only partially

with no diastema and converging incisal

fulfilled the patient’s initial wishes, since

borders best fit the patient’s smile and

he could eat and speak again comforta-

face. This version was then taken as a

bly. He was not, however, totally satisfied

reference for the final restoration pro-

with the appearance of his new smile.

duction (Figs 7e and 7f).

Therefore, before the framework of the



Figs

7c

and

7d Mock-up

versions of possible treatment outcome.


CLINICAL RESEARCH

Fig 7e Preoperative view, chosen mock-up, and final restoration.

Fig 7f Preoperative view, different mock-ups, and final restoration.




and were to be relined at the same ap-

Case 3

pointment that the old reconstructions A 47-year-old female patient attended

were to be removed. Since the patient’s

the Clinic for Fixed and Removable

esthetic concerns were difficult to de-

Prosthodontics

Material

termine, a digital impression was taken

Science of the University of Zurich dis-

and

Dental

intraorally (iTero), and different smile

satisfied with the result of a recently

proposals were designed virtually (Ex-

delivered dental rehabilitation (Fig 8a).

ocad) and printed in A2 colored resin

She complained about the esthetics

(PolyJet MED610) using a 3D printer

and the generalized gingivitis that had

(Objet Eden 260V) (production time: 64

developed around every crown since

min) (Fig 8b). The digitally generated

the restorations had been cemented.

mock-ups were tried in and critically

The dental examination revealed over-

evaluated by the patient and restora-

hangs and narrow interdental spaces

tive team (Fig 8c). The version that was

in nearly every crown, which required

agreed upon to be the best was taken

that the dental rehabilitation be redone.

as a reference for the final restoration

Eggshell provisionals were fabricated

production (Figs 8d and 8e).


CLINICAL RESEARCH

Figs 8b and 8c Mock-up versions of possible treatment outcome.

Fig 8d Preoperative view, chosen mock-up, and final restoration.



Fig 8e Preoperative view, different mock-ups, and final restoration.

Discussion

and agreeing on a clear treatment goal

Digital technologies offer significant im-

tory end result.3 In some cases, the pa-

provement opportunities in many dental

tient’s desires can be difficult to interpret,

and medical fields. Restorative dentistry

and conventional diagnostics involving a

has been one of the disciplines that has

single wax-up and mock-up can be insuf-

profited the most from these technologi-

ficient to determine the desired treatment

are fundamental to obtaining a satisfac-

advancements.14

Among these in-

goal. The need for further wax-ups can

novations, CAD/CAM technologies have

be both time-consuming and expensive.

greatly influenced the production of pro-

Virtual technologies can make this treat-

visional and definitive restorative com-

ment step easier and less expensive as

ponents.10,13,14

As the technology es-

they eliminate the manual work restraints

tablishes and develops further (intraoral

of the dental technician, enabling full

optical scanners, cast optical scanners,

concentration to be focused on the teeth

virtual design software, 3D printers),

shape and arrangement. When the pro-

new indications arise in other treatment

spective restoration volumes have been

phases of the restorative workflow. This

virtually designed, variations of this initial

article presents the advantages offered

sketch can be rapidly made with little ef-

by new digital technologies in the pros-

fort. Several versions can be designed

thodontic diagnostic phase.

and fabricated simultaneously during

cal

Diagnostics are essential for a predict-

the same 3D print without increasing the

able treatment outcome in esthetic den-

costs. Moreover, the printing material is

tistry. Understanding the patient’s needs

inexpensive, which makes the protocol


CLINICAL RESEARCH

affordable (estimated material cost per

CAM workflows using a subtractive ap-

mock-up set print: 12 CHF). The oppor-

proach are able to produce provisionals

tunity to choose among a range of blue-

and definitive restorations with the de-

prints improves patient–dentist–techni-

sired CAD form.18,19 Even though they

cian communication and satisfaction, and

are effective, these workflows present

facilitates the decision-making process.

some limitations, such as color/shade

Nevertheless, some relative limita-

restrictions,

waste

of

considerable

tions exist when producing mock-ups

amounts of material, the impossibility of

using this additive process. Besides the

creating geometries that lie below the

noteworthy initial economic investment

milling bur diameter, and the impossibil-

needed to purchase the hardware (opti-

ity of allowing for the simultaneous mul-

cal scanner, 3D printer), difficulties arise

tiple production of restorations.10,14

when attempting to achieve morphologic

Additive processing routes that would

details digitally. Mastering and becoming

allow polychromatic polymer printing or,

efficient with the design software requires

even more interesting, ceramic layering,

time and learning on the part of the dental

would be extremely valuable. Currently,

technician. Even so, final fine-tuning ad-

some 3D printing companies offer the

justments (incisal edge characterization,

possibility of printing non-dental ceram-

interincisal embrasures, surface texture,

ics effortlessly (Shapeways, Materialise).

etc) must be done manually to achieve a

The printing procedure involves a roller

high-end result. Besides this, the printer

that places a thin layer of ceramic pow-

is incapable of producing structures with

der on a printing platform, and a printing

a thickness of less than 0.3 mm, which

head that deposits organic binder at cer-

could be a limitation when thin buccal

tain desired locations. Thin layers of the

shells are needed to avoid a bulky ap-

ceramic model are overlapped as the

pearance of the mock-up.

platform lowers and the roller spreads

Moreover, the available materials for

new layers of powder. Once the model is

3D printing with the presented protocol

completed, it is then placed in a drying

unfortunately are not biologically and

oven to increase the strength of the ce-

mechanically stable enough to be used

ramic powder structure before it can be

as provisional or definitive restorations.

conventionally fired in a ceramic oven

The 3D printing digital workflow is in-

(Materialise – http://i.materialise.com/

terrupted when the final reconstruction

materials/ceramics). Since the techni-

must be produced. In other words, a di-

cal procedures are already available, it

rect transfer of the diagnostic blueprint

seems reasonable to expect that these

into the definitive restoration is not yet

advances will soon be available in the

achievable through computer-assisted

dental field. Nevertheless, even though

additive procedures. The manual ce-

CAM ceramic printing is feasible, there

ramic layering and contouring of the fi-

is at present no CAD software to cap-

nal restoration performed by the dental

ture tooth color and design the polychro-

technician introduces slight differences

matic, ceramic powder 3D layout in the

to the diagnostic sketches, as was ap-

model. However, this shortcoming is on-

preciated in the cases presented. Other

ly a technical one, and it is only a matter



of effort being invested by the industry in

nician communication without increas-

this field to develop a solution.

ing treatment costs. This improves the

Despite the initial economic invest-

predictability of the treatment outcome,

ment needed to enter the digital work-

an aim that is crucial in contemporary

flow (software, scanners, printers), the

restorative dentistry.

current technical limitations of these young technologies, and the learning curve required to master the virtual tools this pathway offers, dental digitalization

Acknowledgements The authors would like to thank Dr Philipp Grohmann for the courtesy of the third case, and his col-

is an unstoppable phenomenon that

laboration during the development of the presented

will surely push dental standards even

concept. The authors would also like to thank Urs

higher. The incorporation of these technologies into the prosthetic diagnostic phase enhances patient–clinician–tech-

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