Novel Approach for Predictably Matching a Veneer to an Implant Crown QUINTESSENCE OF DENTAL TECHNOLOGY 2019

Digital technology should be expanded beyond methods of fabrication of single-unit crowns to include minimally invasive adhesive restorations inlays, onlays, veneers, digitally guided im

institutions Of all the dental laboratory technology programs in the United States that are accredited by CODA (Commission on Dental Accreditation), only a few currently include dedicated courses in digital technology as an integral part of their programs Similarly, dental schools have yet to fully embrace digital technologies as an integral part of their curriculum It is clear that the logistics of implementation is challenging the eagerness for its application.

Fortunately, several positive attempts have been made to introduce digital ogy to the dental curriculum Just a few weeks ago, the American Dental Education Association (ADEA) organized a conference where deans and invited leadership of all American and Canadian dental schools gathered to discuss digital technologies in dental education and in health care The American College of Prosthodontists (ACP) has also worked very hard to promote a digital curriculum for dental schools CODA recognizes the importance of digital technology and has recently included standards focusing on new technologies with which educational institutions must comply For Dental Laboratory Technology programs, CODA emphasizes that students need to

technol-be exposed to as many new technologies as possible—including digital scanning and digital design (Dental Laboratory Technology CODA Standards 2-19 and 2-20) For Predoctoral Dental Education programs, CODA accreditation standards require that students must be able to evalu-ate, assess, and apply current and emerging science and technology (CODA Standard 2-24); dental schools must show evidence of the use of technology in didactic and clinical components of the curriculum (CODA Standard 3-2); and that patient care must be evidence-based, and dental schools should use evidence to evaluate new technology and products

as well as to guide diagnosis and treatment decisions (CODA Standard 5-2)

Our experience with the Digital Technology Curriculum at the University of Southern California has been amazingly positive Students’ engagement and eagerness to learn has increased, as has the overall quality of their work, since digital technology allows students to become more critical of their own work Digital technology should be expanded beyond methods of fabrication of single-unit crowns to include minimally invasive adhesive restorations (inlays, onlays, veneers), digitally guided implant-supported treatment (treatment planning, surgical guides, and restorations), removable prosth-odontics (digital design and 3D printing), and, of course, crown and bridge restorations

It is time to fully embrace digital technologies in education Implementation of digital technology into dental curricula should be made as early as possible in the student’s education, and not as a “selective” or isolated course at the end of a student’s educational program The next generation of practitioners (dentists and dental technicians) should be exposed

to all the possibilities, advantages, as well as limitations that digital technology brings to the field The way in which ative dentistry has been practiced is changing rapidly Education should follow a similar path by making preservation of dental tissues through minimally invasive adhesive dentistry and digital technology a priority in future dental technicians’ and dentists’ curricula

restor-Please join me in appreciating the collection of superb clinical and scientific works in this edition of Quintessence of Dental Technology, where the fusion of digital technology, adhesion, dental materials, artistry, and implant therapy are chal-lenged to promote esthetic and functional outcomes

Sillas Duarte, Jr, DDS, MS, PhD

In recent years, single anterior implants have become a

predictable treatment option when a tooth is missing

or in need for extraction The situation becomes more challenging when a veneer restoration has to be fabricated next to an anterior implant crown Blending the color and especially the translucency of a veneer restoration with an adjacent crown is always difficult To match both restora-tions in a simple manner, a screw-retained implant crown is the restoration of choice to allow shade matching of the zirconia abutment to the color of the prepared veneer abut-ment tooth When the shade of the zirconia abutment is the same as the shade of the abutment tooth, the dental tech-nician can build up both restorations in the same manner and create an optimal result Key details are explained and depicted with two select clinical cases

1 Adjunct Professor, Department of Preventive and Restorative Sciences,

University of Pennsylvania School of Dental Medicine, Philadelphia,

Pennsylvania, USA; and Private Practice, San Sebastián, Spain.

2 Private Practice, San Sebastián, Spain.

3 Professor of Restorative Dentistry and Chairman, Department of

Pre-ventive and Restorative Sciences, University of Pennsylvania School of

Dental Medicine, Philadelphia, Pennsylvania, USA.

Correspondence to: Dr Iñaki Gamborena, C/ resurrección M Azkue

#6 -4, 20018 San Sebastián, Guipúzcoa, Spain

Email: Gambmila@telefonica.net, www.Drgamborena.com

Yoshihiro Sasaki, CDT2

Markus B Blatz, DMD, PhD3

• Final result 3 years after delivery of a single-tooth screw-retained implant restoration A 3.0-mm NobelActive implant (Nobel Biocare) was placed in the area of the maxillary right central incisor and a feldspathic veneer on the left central incisor.

• Initial situation reveals a vertical and horizontal ridge defect in the area of the right central incisor

• Implant placement with a Slim healing abutment in a one-stage surgery.

• Subepithelial connective tissue graft (CTG) was harvested from the tuberosity and sutured crestally on the ridge to minimize the tissue defect.

3 years postoperative

Preoperative

Provisional implant restoration with a flat

tissue scallop allows for shaping of the

ideal scallop with gingivectomy

Zirconia abutment selection and shade communication. Final implant impression was made to design and fabricate the zirconia implant

abutment before the veneer preparation.

Gingival recontouring through

gingivec-tomy to recreate ideal gingival scallop and

align gingival levels

Intracrevicular margin location for optimal tissue volume support and scallop. Try-in of the zirconia abutment: Light-cure stain was applied to accurately communi-

cate abutment shade to the technician.

Abutment shade was reproduced in the

laboratory with corresponding chroma and

value.

Second try-in of the zirconia abutment to verify base shade of preparations before final delivery of the restorations.

The two veneers were layered and completed at the same time and in the exact same manner.

The veneer on the natural tooth was tried

in before cementation with glycerin gel to

assess shade, value, and color match of

the two restorations.

The feldspathic veneer was then acid etched, silanated, and bonded to the abutment tooth.

Bonding only one veneer next to the implant restoration decreases bonding difficulty.

The zirconia abutment was bonded to a titanium post with resin

cement due to the lack of metal connection for the NobelActive

2 years

Initial

Provisional restoration on maxillary left

central incisor and composite resin

restoration on right central incisor were

made to adequately support the soft

Final impression was made with a

customized impression coping to support

emergence profile in the same manner as

the provisional restoration.

Design and fabrication of the retained final zirconia abutment restoration with angulated screw channel (ASC, Nobel Biocare).

screw-Veneer preparation and ASC zirconia abutment in situ.

Shade communication of the zirconia on

day of veneer preparation with light curing

(Optiglaze, GC).

Base color abutment is fired on top of the zirconia to match the shade of the natural abutment tooth.

Second try-in of the zirconia abutment is necessary after adjustment to verify color match of both abutments.

Porcelain veneering is completed in the

same manner for both restorations. Laminate veneer on the natural tooth is bonded first to ensure accurate

adapta-tion, followed by the screw-retained implant restoration to control interproximal contact areas.

Final restorations on the master cast with the same veneer layering.

Restorations: Screw-retained implant restoration to replace maxillary left central incisor and porcelain laminate veneer

restoration on the right central incisor

Materials used: Maxillary left central incisor—white color ZR NobelProcera, with ASC abutment, 20-degree angulation

Maxillary right central incisor—feldspathic veneer cemented with translucent resin cement G-CEM LinkAce (GC) Creation

ZI-CT porcelain used for both restorations.

2 years

Benefits of this Protocol:

• Designing a screw-retained implant restoration allows

the clinician to try in the zirconia abutment and match it

to the shade of the natural abutment tooth after veneer

preparation The angulated screw channel (ASC, Nobel

Biocare) can be angulated more than 25 degrees and

thereby increases the possibility to fabricate screw-

retained implant restorations by approximately 40%

• The bonding procedure is simplified since only one

ve-neer is bonded The screw-retained restoration veve-neer is

built up in the same manner as the laminate veneer

• There is improved accuracy and adjustment of the

ve-neer cementation as well as the interproximal contacts

between the veneer and the implant restoration The

ve-neer is bonded first to ensure optimal marginal

adapta-tion Then, the screw-retained implant restoration is torqued down and interproximal contact areas are ad-justed until ideal pressure is achieved

• The shade match between both materials is better since the veneer porcelain layering is performed in the same manner on a verified base color abutment The intention

is always to cement the veneer with a translucent ment to not interfere with the overall value of the restora-tion and match of both restorations

ce-One disadvantage of this technique is that a second try-in appointment is necessary to verify the base shade of the prepared veneer and the zirconia abutment color to achieve the results illustrated in the cases presented

In all of our patients restored with a single implant, the teeth adjacent to the implant are splinted to avoid continuous

extrusion of the teeth, especially in Class II malocclusion cases.

1 Advanced Program in Operative & Adhesive Dentistry, Division of Restorative

Sciences, Herman Ostrow School of Dentistry, University of Southern

California, Los Angeles, California, USA.

2 Private Practice, Madrid, Spain; Advanced Program in Operative & Adhesive

Dentistry, Herman Ostrow School of Dentistry, University of Southern

California, Los Angeles, California, USA.

3 Private Practice, Lisbon, Portugal; Advanced Program in Periodontics,

Herman Ostrow School of Dentistry, University of Southern California,

Los Angeles, California, USA.

4 Division of Restorative Sciences, Herman Ostrow School of Dentistry,

University of Southern California, Los Angeles, California, USA.

Correspondence to: Dr Neimar Sartori, Division of Restorative Sciences,

Herman Ostrow School of Dentistry, University of Southern California,

925 W 34th Street, DEN 4365, Los Angeles, CA 90089-0641, USA

Email: sartori@usc.edu

Complex Anterior Rehabilitations

The increased demand for high-quality, functional,

and natural-looking restorations has driven the

de-velopment of new restorative materials,

technolo-gies, and techniques Esthetic rehabilitation that combines

the advantages of implant-supported prostheses to restore

missing dentition and bonding procedures to restore

ad-jacent teeth using minimally invasive approaches allows

clinicians to significantly improve esthetics and correct

altered teeth shape ultraconservatively

In the past, the main objective of an implant treatment

was to ensure osteointegration,1 which might not always

presuppose a successful esthetic outcome.2 With the

de-velopment of bone grafting materials, guided bone

regen-eration techniques, and digital treatment planning, the

concept of implant treatment has changed to

“restoration-driven implant placement.”3 Consequently, there has been

an increased demand for esthetic and functional

restora-tions with healthy peri-implant soft tissue.4 Nowadays, one

of the biggest challenges in dentistry is to restore a single anterior tooth with an implant-supported restoration that mimics all lost structures as closely as possible to those of the contralateral or original tooth.5

The advancements in dental ceramics and adhesive technology allow ultraconservative treatments to improve esthetics and function by modifying the morphology and/

or shade of anterior teeth The main advantage of using ultrathin ceramic restorations is maximum enamel preser-vation, which ensures the long-term success of the restor-ative treatment.6 However, some situations, such as tooth discoloration and/or malposition, may require a large amount

of dentin to be exposed during tooth preparation In such situations, the clinician should be aware that the adhesive bonding protocol must be modified to create a reliable long-term resin-dentin interface

Therefore, the aim of this article is to describe

ultracon-servative procedures to restore the esthetics and function

of patients exhibiting discolored, missing, and misaligned

anterior teeth while ensuring the appropriate longevity of

the restorations

CASE PRESENTATION

Initial Diagnosis and Treatment Planning

A 34-year-old systemically healthy nonsmoking male

pre-sented to the Advanced Operative & Adhesive Dentistry

Program, Herman Ostrow School of Dentistry of University

of Southern California, for esthetic treatment of his

ante-rior teeth The patient was missing the maxillary left central

incisor due to trauma, and the right central was discolored

due to endodontic therapy

The success of esthetic and functional treatment of the anterior teeth depends on an adequate treatment plan Photographs were taken of the patient’s face with the lips

in resting position as well as smiling to evaluate the lip competence and lip line position Intraoral photographs were taken to evaluate the dental arrangement, smile line, gingiva position, occlusal planes, teeth color and shape, as well as emergence profile of the teeth (Figs 1a and 1b) A two-dimensional digital treatment planning was done using presentation software (Keynote, Apple) to facilitate inter-disciplinary communication, as well as to discuss treat ment options and limitations with the patient (Figs 2a and 2b)

Guided Bone Regeneration

Tooth extraction initiates various soft and hard tissue terations that lead to a reduced alveolar ridge contour,7

al-which is exacerbated if the tooth is traumatically removed

Figs 1a and 1b Preoperative intraoral views The patient is missing the maxillary left central incisor due to dental

trauma, and the right central is discolored due to endodontic therapy.

Fig 2a Preoperative analysis of teeth outline and inclination Note the flare of the teeth and inadequate relationship with the proposed midline

Fig 2b Digital design depicting the ideal teeth proportions (width/length ratio) and inclination toward the midline

Digital analysis was used to explain the advantages and limitations of the esthetic treatment proposed.

In order to place an implant in the correct position for a

screw-retained restoration, as well as have adequate

gingi-val architecture and esthetics, the alveolar ridge deficiency

must be corrected.8,9 Reconstruction of the alveolar bone

can be achieved through many regenerative surgical

pro-cedures, including guided bone regeneration; onlay

graft-ing; combinations of onlay, veneer, and interpositional inlay

grafting; distraction osteogenesis; ridge splitting; as well as

a multidisciplinary approach utilizing forced eruption.10

The tent screw pole technique is a safe and effective

method for augmentation of bone height and width in

se-verely resorbed ridges.10 During the healing period, the

tenting screws maintain the volume and the geometry of

the space This allows for the stabilization of the blood clot

and undisturbed healing The tenting effect facilitates

suc-cessful bone augmentation with a high predictability, low

risk of complications, and reduced healing period.10 This

helps prevent the soft tissues from contracting around the

graft material and subsequently displacing it or causing

physiologic resorption.9

A crestal incision with vertical releases was made and a full-thickness mucoperiosteal flap was elevated (Fig 3) Two 12-mm-long titanium screws (Trutent Tenting Screw, ACE Surgical Supply) were placed in the alveolar ridge de-ficiency area with approximately 4 mm of the screw ex-posed above the alveolus, maintaining space for the graft (Fig 4) Autologous bone was harvested from the retromo-lar area with a bone scraper (Fig 5) The autogenous bone chips were mixed with deproteinized bovine bone mineral (Bio-Oss, Geistlich Pharma) at a ratio of 1:1 The graft ma-terial was placed into the site until only the surface of the screws was visible (Fig 6) Then, a resorbable membrane (OsseoGuard, Zimmer Biomet) was placed over the screws and grafted site Additional stabilization of the resorbable membrane was achieved using two tacks in the apical portion (Fig 7) The surgical site was sutured using 5/0 polytetrafluoroethylene (Cytoplast PTFE suture, Biohori-zons) and 5/0 polypropylene sutures (Perma Sharp Suture, Hu-Friedy) to achieve tension-free primary closure (Fig 8)

Fig 3 Crestal incision with vertical releases and full-thickness mucoperiosteal flap elevation to expose the alveolar ridge

deficiency site.

Fig 4 Tenting titanium screws positioned strategically in the alveolar ridge deficiency to create the potential threshold for

horizontal bone gain of approximately 4 mm.

Fig 5 Autogenous bone graft harvested from the retromolar area with a bone scraper.

Fig 6 Autograft bone mixed with deproteinized bovine bone mineral applied on the alveolar ridge deficiency to cover the

screw heads.

Fig 7 Resorbable membrane placed over the screws and grafted site, stabilized by two tacks in the apical portion.

Fig 8 Surgical site sutured, achieving tension-free primary closure.

Digital Treatment Planning for Implant

Placement

After 6 months of healing (Fig 9), a cone beam computed

tomography (CBCT) scan was taken to evaluate the

augmented bone site A maxillary esthetic and functional

wax-up (Fig 10) was digitalized using CAD/CAM software

(PlanScan, Planmeca) and merged with the CBCT scan

(Fig 11) using implant planning software (coDiagnostiX, Dental Wings) The implant position and angulation were digitally determined, and a surgical guide for the implant placement was fabricated The guide was printed and a sleeve designed for the Straumann Implant System to be used was placed on the implant access hole (Fig 12) The surgical guide fit was then intraorally verified to confirm the adaptation before the surgical implant placement (Fig 13)

Fig 11 Diagnostic wax-up digitalized and combined with the patient’s maxillary impression and CBCT file to plan the implant placement position and angulation.

Fig 12 Surgical guide printed with the selected implant sleeve.

Fig 13 Intraoral evaluation of the surgical guide fit.

11

Implant Guided Surgery and Coronal

Advancement

To minimize the surgical trauma, a vestibular incision

sub-periosteal tunnel access (VISTA) was used to retrieve the

tenting screws.11 Through this incision, a subperiosteal

tunnel was created using a series of specially designed

elevators, extending toward the vestibular depth, as well as

the ridge crest (Fig 14)

After removal of the tenting screws, a sigmoidal incision

was made on the palatal side to gain access to the bone

crest (Fig 15) The drilling sequence was done according

to the digital planning using the surgical guide and the responding sleeves and drill handles (Fig 16) After the implant bed preparation, a Straumann Bone Level 4.1 × 12-mm implant was inserted subcrestally with a torque of

cor-35 Ncm (Fig 17) and a 4-mm-long RC healing abutment was placed Lastly, using the VISTA technique, a coronal advancement was done for the adjacent lateral incisor and canine using 5/0 polypropylene suture (Perma Sharp Suture, Hu-Friedy) bonded to correct the gingival level The vestibular incision was sutured with 5/0 PTFE suture (Cytoplast PTFE suture, Biohorizons) (Fig 18)

Fig 14 Vestibular incision subperiosteal tunnel access (VISTA

technique) to retrieve the tenting screws.

Fig 15 Sigmoidal incision on the palatal side to gain access to

the bone crest.

Fig 16 Drilling sequence for the implant placement according

to the digital treatment planning.

Fig 17 Implant placed subcrestally.

Fig 18 VISTA technique of coronal gingival advancement to

correct the gingival level on maxillary left side.

15 14

16

CAD/CAM Provisional Restoration

Fabrication

Adequately restoring function and esthetics for implant

restorations in the esthetic zone is a challenge.12 In

addi-tion to surgical modificaaddi-tion, soft tissue management with

provisional restoration plays a crucial role in the esthetic

outcome.1 In other words, the final esthetic results of

sin-gle implant restorations are influenced by the shape and

position of the implant, soft tissue management during the

surgery, design of the provisional restoration, type of

abut-ment, and characteristics of the definitive restoration.5

Therefore, to create a satisfactory esthetic treatment it is

important to mimic all lost structures as closely as possible

to those of the contralateral tooth.13

Four months after the implant placement (Fig 19), the

healing abutment was removed and immediately replaced

by a digital scan-post A radiograph was taken to confirm

the scan-post position, a scan-body was then placed on the

scan-post, and the maxilla was scanned using an intraoral

scanner (CEREC, Dentsply Sirona) The virtual 3D models

of the scan-post, diagnostic wax-up, mandible, and patient’s occlusion were imported into the CAD/CAM designing software to fabricate an interim implant-supported restora-tion (Fig 20)

The aim of a provisional implant-supported restoration

is to restore the masticatory function and the contour of the peri-implant soft tissue to create an optimum emergence profile for the final restoration The provisional restoration was designed, based on the morphology of the diagnostic wax-up, and milled in a block of microfiller-reinforced poly-acrylic (CAD-temp Multicolor, VITA Zahnfabrik) (Fig 21a) The screw-retained provisional restoration was polished and bonded to the titanium base (TiBase, Dentsply Sirona) using dual-cure resin cement (Fig 21b)

Direct Gingival Recontouring

The provisional implant restoration was connected to the implant and the subgingival contours were gradually re-contoured to modify the soft tissue profile around the im-

Fig 19 Clinical aspect 4 months after implant placement and coronal gingival advancement Fig 20 Virtual 3D models imported into CAD/CAM designing software to fabricate the provisional screw-retained implant restoration.

Figs 21a and 21b Interim restoration milled, polished, and connected to the titanium base.

plant (Fig 22) The direct contouring technique allows the

clinician to gradually modify the restoration while gauging

the effect on the peri-implant tissues to optimize the

es-thetic results Areas of residual gingival blanching that

were present after 15 minutes were reduced; in areas with

a lack of peri-implant tissues, pressure flowable nanofilled

composite resin (Filtek Supreme Ultra, 3M ESPE) was

added.14 The modified areas of the emergence profile of

the provisional restoration were then properly polished for

precise soft tissue management This approach allows the

tissues to gradually adapt to the pressure, without

over-stressing the elasticity of the gingival tissue,15 as well as

allows soft tissue maturation and a chance for the patient

to try the esthetics and function of the restoration before

the final inpression.16

The provisional restoration was relined and reshaped

three times, so that the soft tissue was managed and

guid-ed to achieve the desirguid-ed emergence profile (Fig 23)

Ide-ally, the modified emergence profile of the provisional

restoration should contain two specific areas: (1) a

con-cave area, about 1 mm subgingival and continuing for 360

degrees around all margins of the provisional restoration,

to provide a nonsurgical increase in tissue thickness and

long-term stability, and (2) an interproximal subgingival area

that should be convex to support the papillae (Fig 24).5

After 6 weeks, a customized impression coping was cated to transfer the emergence profile contours and posi-tion of the gingiva from the provisional restoration to the definitive prosthesis (Fig 25)

fabri-Shade Correction and Restoration Prototypes Try-in

Bleaching procedures should be performed before the tooth preparations to balance the shade among different teeth The teeth were bleached using a combination of in-office and at-home techniques,17 as well as nonvital tooth bleaching on the endodontically treated tooth Two weeks after completion of the bleaching treatment, shade match-ing was done visually and with the aid of a spectrophotom-eter (Easy Shade, Vita), and dental photographs were taken

to register the color of the hydrated teeth

The morphology of the restoration prototypes were transferred from the waxed diagnostic cast to the patient’s mouth using a polyvinyl siloxane impression filled with a chemical-cure multifunctional methacrylic ester resin (In-tegrity, Dentsply Sirona).6 After the resin polymerization,

Fig 24 Aspects of the completed interim screw-retained restoration used to modify the soft tissue profile around the implant.

Fig 25 Customized impression coping fabricated to transfer the emergence profile contours and position of the gingiva from the interim to the final implant-supported restoration.

the excesses were carefully removed with a surgical

scal-pel blade (Fig 26) The restoration prototype try-in allowed

the dentist and patient to evaluate whether the proposed

esthetic and functional treatment was correct or if any

ad-justments were necessary If any intraoral corrections are

made, an impression of the restoration prototype must be

taken after the adjustments to transfer those changes to

the technician or to the CAD/CAM software Moreover,

both functional movements—anterior and canine guidance—

and phonetics must be evaluated before starting tooth

preparation to ensure the final restorations will not

inter-fere with the patient’s speech nor masticatory function.18

TOOTH PREPARATION

Before tooth preparation begins, the patient must sign a

form indicating approval of the esthetics, shape, and

posi-tion of the restoraposi-tion prototypes The success of ultra-thin

bonded ceramic restorations requires maximum enamel

preservation during the tooth preparation When there is

exposed dentin, the ceramic veneer must be thicker, at

least 0.5 mm, to withstand the stresses of flexion and

compression on the resin-dentin interface Moreover, the

dentin-bonded interface is susceptible to hydrolytic and

enzymatic degradation, which can cause margin

discolora-tion, secondary caries, and veneer debonding over time.19,20

To maximize enamel preservation, the tooth preparation

must be focused on creating a path of insertion for the

ceramic restorations, with evaluation of the need of

reduc-tion of the facial surface volume, teeth alignment and

an-gulation, as well as the color of the dental substrate.6 When

the tooth shade is favorable, minimal or no tooth reduction

is necessary The tooth preparation must be done based

on the contour of the final restorations, guided by the

res-toration prototypes, as well as vertical, horizontal, and

inci-sal reduction guides (Fig 27).21 Ideally, when only a minor color change is necessary, the tooth reduction should be ultraconservative, maintaining the inner enamel through-out the entire preparation.22

When the difference between the desired final tion color and the tooth preparation color is one shade or more, such as from A2 to A1, the restoration thickness plays an important role in modifying the color of the sub-strate.23 If the desired final color is up to two shades brighter, a facial reduction of 0.6 mm is necessary In this situation, the final shade is a combination of the colors of the tooth substrate, resin cement, and the ceramic restora-tion.23 However, when a correction of three or more shades

restora-is necessary to achieve the desired color, such as from A4

to A1, the restoration must mask the discoloration of the dental substrate In this case, a facial and proximal reduc-tion of 0.9 mm is necessary, and the gingival margin must

be subgingival on the esthetic areas.23

After the teeth reduction is completed, the preparations should be polished to ensure maximum adaptation of the ceramic restoration with a reduced luting film thickness (Fig 28) Moreover, the tooth preparation stump shades must be documented using digital photography to facilitate communication with the laboratory technician

Final Impression

The location of the gingival finishing line of the preparation will determine the need for retraction cords during the final impression In cases when the finishing line is supragingi-val, the final impression should be taken without retraction cords, maintaining the gingiva in its natural position Resto-rations with cervical overcontour change the natural emer-gence profile of the teeth, promoting plaque accumulation, gingival inflammation, and, consequently, gingival reces-sion over time.24

When the tooth preparation extends subgingivally,

re-traction cords must be used for soft tissue displacement,

exposing the preparation finishing line In such situations, a

dual-cord impression technique displaces the facial and

interproximal papilla, allowing the technician to create the

new emergence profile for the bonded restorations if

nec-essary The customized impression coping was connected

to the implant and a periapical radiograph was taken to

confirm the correct position A one-step dual-cord

impres-sion technique was used for this case (Fig 29)

Provisional Restorations

The provisional implant-supported restoration was

con-nected to the implant, and chairside provisional

restora-tions were fabricated for the other prepared teeth The

tooth preparations were spot-etched with 35% phosphoric

acid, and an etch-and-rinse adhesive was applied and

light cured The impression filled with chemical-cure

multi-functional methacrylic ester resin was seated on the tooth preparations and kept in position until polymerization was complete All excesses were removed using a surgical scalpel blade and gingival embrasures opened to allow the patient to clean the interproximal spaces with dental floss connected to a floss threader.25

Restoration Fabrication

Porcelain veneers were fabricated with feldspathic

ceram-ic (Creation CC, Creation Willi Geller) The implant crown was fabricated with layered feldspathic ceramic over a zirconia implant abutment (Fig 30) The restorations were fabricated using a build-up layering technique, which al-lowed the laboratory technician to stratify different ceram-

ic shades and translucency to mask the discoloration of the right central incisor After finishing the firing cycle, a natural-looking surface morphology was created during the restoration finishing and polishing procedures (Fig 31)

Fig 27 Tooth preparation over the

restoration prototypes to ensure

maximum enamel preservation.

Fig 28 Polishing of tooth preparations

before the final impression is taken.

Fig 29 Customized impression coping

connected to the implant, and retraction

cord placed before the impression.

Fig 30 Layering of zirconia

implant-supported crown with feldspathic

ceramic.

Fig 31 Feldspathic ceramic–layered

crown and veneer restorations after

finishing and polishing.

31 30

Restoration Try-in and Implant Crown

Delivery

The provisional restorations were removed and teeth

prep-arations cleaned using a pumice-water slurry and low-speed

prophy cup to remove salivary debris and any bacterial

plaque in a gentle way to prevent gingival dilacerations

(Figs 32a and 32b) The correct seating and contact points

of the implant-supported crown and veneers were

con-firmed clinically and radiographically during the try-in

The implant-supported crown was tightened with a final

torque of 35 N (Figs 33a and 33b), and the screw-access

hole of the abutment was sealed with PTFE tape and

nano-filled composite resin (Filtek Supreme Ultra, 3M ESPE)

Ceramic Restoration Intaglio Preparation for Bonding

After the patient signed the form approving the shape and shade of the proposed treatment, the veneers were re-moved and prepared for the bonding procedures

The intaglio surface of the veneers was cleaned with a steam jet to remove the try-in paste and other debris All veneers were etched with 9% hydrofluoric acid (Porcelain Etch, Ultradent) for 90 seconds, rinsed under running wa-ter for 60 seconds, and then cleaned with 35% phosphor-

ic acid (Ultra-Etch, Ultradent) for 60 seconds to remove crystalline precipitates that accumulate in the microporosi-ties The intaglio surfaces were dried with a stream of air, a universal primer for conditioning glass-ceramic restorations (Monobond Plus, Ivoclar Vivadent) was applied for 60 sec-onds, and any remaining excess primer was dispersed with

a strong stream of air.26

Veneer Bonding

The operative field was isolated with a rubber dam to

in-hibit any contamination by gingival fluid during the bonding

procedures A special clamp (W00) was used to retract

both the rubber dam and the gingiva, exposing the

subgin-gival cervical margin of the central incisor, and adjacent

teeth were protected with PTFE tape and the tooth

prepa-ration microetched with 27-micron aluminum oxide for 10

seconds

The bonding procedure must be performed according

to the dental substrate Resin-dentin bonding has become

reliable with the introduction of hydrophilic adhesive

sys-tems The low durability of resin-dentin bonding is related

to the hydrolysis of unprotected collagen fibrils by

host-derived enzymes in the incomplete resin-infiltrated hybrid

layer.27,28 Over time, collagen fibril degradation by

metallo-proteinases (MMPs)27 and the cysteine-cathepsins29

pro-mote the hydrolytic breakdown of the bonded interface

One strategy to avoid the endogenous collagenolytic

activ-ity is the use of MMP inhibitors.20 It has been

demonstrat-ed that when chlorhexidine digluconate is applidemonstrat-ed after the

acid etching and prior to the adhesive system application,

it helps to maintain the integrity of the hybrid layer over

time.30

So, conscious of the limitation and challenges of term resin-dentin bonding, tooth preparation of the central incisor was etched with 35% phosphoric acid (Ultra-Etch, Ultradent) for 15 seconds in dentin and 30 seconds in enamel (Fig 34) After rinsing for 30 seconds, 2% chlorhex-idine digluconate solution (Cavity Cleanser, Bisco) was ap-plied to acid-etched dentin for 30 seconds and the excess was removed prior to the adhesive application (Fig 35) A universal multimode adhesive system (Adper Scotchbond Universal, 3M ESPE) was applied on the etched surface of the enamel and dentin and rubbed for 20 seconds (Fig 36) The adhesive was air dried for 15 seconds to com-pletely evaporate the solvent31 and individually light cured for 10 seconds (Figs 37a and 37b) When dentin is ex-posed on the tooth preparation, the adhesive system must

long-be independently polymerized to ensure the formation of a dependable resin-dentin hybrid layer.32 Moreover, the den-tin bonding agent selected should create a thin adhesive film thickness; otherwise, it will interfere with the restora-tion adaptation onto the tooth preparation Universal adhe-sive systems are therefore the only type of dental adhesives that can be polymerized safely before placement of resto-rations

The restoration was adhesively bonded using resin ment (Variolink Veneer, Ivoclar Vivadent) After the veneer

ce-Fig 34 Preparations etched with 35%

phosphoric acid.

Figs 37a and 37b After complete

evapo-ration of solvents, universal adhesives can

be light cured without interfering with the

seating of final restorations due to the

minimal thickness of the adhesive layer

This technique is especially important to

obtain superior sealing of exposed dentin

surfaces and to enhance bond strength.

Fig 35 Chlorhexidine digluconate 2%

solution applied to acid-etched dentin to inhibit the action of MMPs.

Fig 36 Universal adhesive system applied

on etched enamel and dentin.

was seated, the excess cement was removed using an art

brush (Fig 38) and then light cured for 20 seconds A layer

of glycerin gel was applied on the bonded interface to

pre-vent the oxygen-inhibited layer of resin cement before the

final polymerization of each surface for 60 seconds (Fig

39) After rinsing off the glycerin gel, any remaining

ce-ment was removed from the margin using a surgical

scal-pel blade (Fig 40) All the other veneers were adhesively

bonded following the same bonding protocol (Fig 41)

CONCLUSION

The success of anterior implant restoration in areas with

an inadequate amount of bone is dependent on the disciplinary treatment planning A broad understanding of the surgical and restorative procedures informs the selec-tion of the best bone regeneration/augmentation technique and soft tissue manipulation during the implant placement surgery Moreover, the use of a customized interim ana-tomical screw-retained restoration allows the soft tissues

multi-to gradually adapt multi-to the pressure and mature multi-to create an adequate emergence profile for the final restoration

Fig 38 Overflow of resin cement removed from the margins using art brushes before final polymerization.

Fig 39 Final polymerization of the bonded veneer under air block.

Fig 40 No 12 blade used to carefully remove minor excess of resin cement after polymerization.

Fig 41 Intraoral view of the final restorations.

41

amount of dentin is exposed during the tooth preparation,

the bonding protocol must be modified to ensure

long-term success of the resin-dentin interface The use of

MMP inhibitor, dentin bonding system selection, complete

evaporation of bonding agent solvent, and individual

po-lymerization of the adhesive system before seating the

restoration are crucial steps to ensure the longevity of the

resin-dentin interface

ACKNOWLEDGMENTS

Thanks to Faisal Alshehri, BDS, Advanced Program in Operative &

Ad-hesive Dentistry candidate, for assisting during the bonding procedures

of this case, and to Nick Morozov, CDT, for fabricating the ceramic

res-torations.

REFERENCES

1 Jemt T, Pettersson P A 3-year follow-up study on single implant

treatment J Dent 1993;21:203–208.

2 Buser D, Martin W, Belser UC Optimizing esthetics for implant

resto-rations in the anterior maxilla: Anatomic and surgical consideresto-rations

Int J Oral Maxillofac Implants 2004;19(suppl):s43–s61.

3 Garber DA, Belser UC Restoration-driven implant placement with

restoration-generated site development Compend Contin Educ Dent

1995;16:796–804.

4 Son MK, Jang HS Gingival recontouring by provisional implant

resto-ration for optimal emergence profile: Report of two cases J

Peri-odontal Implant Sci 2011;41:302–308.

5 Soares C, Soares LM, Duarte GF, Sartori N Maintaining the esthetics

of anterior immediate implant placement Quintessence Dent Technol

2015;38:113–125.

6 Clavijo V, Sartori N, Phark JH, Duarte S Novel guidelines for bonded

ceramic veneers: Part 1 Is tooth preparation truly necessary?

Quin-tessence Dent Technol 2016;39:7–25.

7 Jung RE, Philipp A, Annen BM, et al Radiographic evaluation of

dif-ferent techniques for ridge preservation after tooth extraction: A

ran-domized controlled clinical trial J Clin Periodontol 2013;40:90–98.

8 Tan WL, Wong TL, Wong MC, Lang NP A systematic review of

post-extractional alveolar hard and soft tissue dimensional changes in

hu-mans Clin Oral Implants Res 2012;23(suppl 5):s1–s21.

9 Deeb GR, Tran D, Carrico CK, Block E, Laskin DM, Deeb JG How

effective is the tent screw pole technique compared to other forms of

horizontal ridge augmentation? J Oral Maxillofac Surg 2017;75:

Imober-14 Kim TH, Cascione D, Knezevic A Simulated tissue using a unique pontic design: A clinical report J Prosthet Dent 2009;102:205–210.

15 Paul SJ, Jovanovic SA Anterior implant-supported reconstructions: A prosthetic challenge Pract Periodontics Aesthet Dent 1999;11:585– 590.

16 Alani A, Corson M Soft tissue manipulation for single implant rations Br Dent J 2011;211:411–416.

resto-17 Bernardon JK, Sartori N, Ballarin A, Perdigão J, Lopes GC, Baratieri

LN Clinical performance of vital bleaching techniques Oper Dent 2010;35:3–10.

18 Fradeani M (ed) Esthetic Rehabilitation in Fixed Prosthodontics Vol 1: Esthetic Analysis: A Systematic Approach to Prosthetic Treatment Chicago: Quintessence Publishing, 2004.

19 Sartori N, Peruchi LD, Phark JH, Duarte S Jr The influence of sic water permeation on different dentin bonded interfaces forma- tion J Dent 2016;48:46–54.

intrin-20 Mazzoni A, Angeloni V, Sartori N, et al Substantivity of carbodiimide inhibition on dentinal enzyme activity over time J Dent Res 2017; 96:902–908.

21 Gürel G Predictable, precise, and repeatable tooth preparation for celain laminate veneers Pract Proced Aesthet Dent 2003;15:17–24.

por-22 Sartori N, Alsamman R, Bocabella L, et al The adhesive restorative complex (ARC) concept Quintessence Dent Technol 2017;40:48–65.

23 Sulikowski AV, Yoshida A Clinical and laboratory protocol for porcelain laminate restorations on anterior teeth Quintessence Dent Technol 2001;24:8–22.

24 Ferencz JL Maintaining and enhancing gingival architecture in fixed prosthodontics J Prosthet Dent 1991;65:650–657.

25 Vailati F, Belser UC Full-mouth adhesive rehabilitation of a severely eroded dentition: The three-step technique Part 2 Eur J Esthet Dent 2008;3:128–146.

26 Tian T, Tsoi JK, Matinlinna JP, Burrow MF Aspects of bonding tween resin luting cements and glass ceramic materials Dent Mater 2014;30:e147–e162.

be-27 Breschi L, Mazzoni A, Ruggeri A, Cadenaro M, Di Lenarda R, De Stefano Dorigo E Dental adhesion review: Aging and stability of the bonded interface Dent Mater 2008;24:90–101.

28 Pashley DH, Tay FR, Yiu C, et al Collagen degradation by host-derived enzymes during aging J Dent Res 2004;83:216–221.

29 Nascimento FD, Minciotti CL, Geraldeli S, et al Cysteine cathepsins

in human carious dentin J Dent Res 2011;90:506–511.

30 Carrilho MR, Geraldeli S, Tay F, et al In vivo preservation of the hybrid layer by chlorhexidine J Dent Res 2007;86:529–533.

31 Fu J, Saikaew P, Kawano S, et al Effect of air-blowing duration on the bond strength of current one-step adhesives to dentin Dent Mater 2017;33:895–903.

32 Lührs AK, Pongprueksa P, De Munck J, Geurtsen W, Van Meerbeek

B Curing mode affects bond strength of adhesively luted composite CAD/CAM restorations to dentin Dent Mater 2014;30:281–291.

D E L I C AT E Incorporating elements into the smile design that

visu-ally translate each patient’s personal identity may help dentists provide restorations that correspond to the esthetic as well as the psychological features of the cre-ated image This can positively affect patients’ emotions, behavior, and confidence, and thus their reaction to the definitive treatment outcome

The purpose of this article is to show that in addition to the esthetic rules established throughout time, the emo-tional expression of the treatment, represented by the shapes and lines that constitute a smile, should also be taken into consideration during the treatment planning Symbols of the “visual language” together with 3D soft-ware that immediately coverts this data into a 3D wax-up STL file for personalized smile design could be a powerful tool for planning such new smile designs

Visual Identity of the Smile (VIS)

1 Private Practice, Istanbul, Turkey; Visiting Professor, New York University, New York, New York, USA.

2 Private Practice, Barbacena, Brazil.

3 Assistant Professor, Department of Prosthetic Dental Medicine, FDM, MU-Sofia, Bulgaria.

MU-Sofia, Bulgaria.

5 Dental Technician, Well Lab, São Paulo, Brazil.

Correspondence to: Dr Galip Gürel, Tesvikiye cad Bayer apt 63/6,

Nisantasi, Istanbul, Turkey Email: galipgurel@galipgurel.com

ticularly useful in targeting adaptive behavior.1,2

Research in the areas of neuroscience and cognitive

psychology suggests that facial traits are unconsciously

noticed by the observer and generate sensations that

in-fluence the way a person is perceived A quick observation

of any human face creates a remarkable first impression.3,4

Esthetic outcomes in dental treatment have become

more important to patients Regardless of the complexity of

the treatment, patients are seeking better-looking smiles.5

However, often the final esthetic results may fail to meet

the patient’s expectations due to disharmony between the

smile design and the patient’s identity The patient may feel

that the restored teeth do not really “belong” to him or her

Without the proper knowledge, the origin of this

dishar-mony can be difficult to identify.6 The massive and

some-times inadequate use of the term esthetics, especially

when it is limited to techniques and materials, misleads

professionals who seek to provide or give back to their

pa-tients the so-desired beauty Despite being the highest

goal of esthetic dentistry, the attainment of real beauty is

more complex than it seems

Esthetics is defined as the comprehension of the visual

principles and parameters that generate a pleasant image

It is therefore a rational, logical, analytical study of beauty.7

Beauty, on the other hand, is the emotional, complex

per-ception of the whole; which at the same time includes, and

sometimes excludes, the esthetic principles, but above all

else it is grounded on identity

Beauty is the product of human perception through its

many senses (visual, olfactory, tactile, hearing, and

gusta-tory) It can be rationally evaluated, but its perception

in-volves an emotional, unconscious, and fulminant process

The gift of perceiving beauty is an innate characteristic of

the human being The dental practice, as well as any other

disciplines that treat the human being, should be

con-cerned about the harmonization of its results with the whole

After all, beauty in dentistry reveals itself through smiles

that express much more information than symmetry,

pro-portion, and alignment Known as “the science of beauty in

nature and art,” esthetics is responsible for the scientific

investigation of the physiology and psychology of

percep-tion and for establishing visual organizapercep-tional foundapercep-tions

smiles, but some studies demonstrate that if applied

strict-ly, its effect becomes one of artificiality, leading to ness and the loss of attraction.8

plain-Esthetic parameters generally represent average acteristics presented in a given population varying accord-ing to gender and age They are important references for the diagnosis and treatment plan but may be insufficient for the total satisfaction of some patients when applied rigorously Their use must be relativized, taking into account physical preoperative characteristics, personality, and per-sonal preferences

char-In order to understand the relationship between the smile design and its emotional acceptance, the authors have been researching the concept of Visagism and its application to dentistry and smile designs since 2007.9

VISAGISM

Derived from the French word for face, visage, “Visagism” describes the study of the face in terms of its constituent traits, the esthetic relation among its elements, and its vi-sual expression The Visagism concept was defined by the plastic artist Philip Hallawell as the art of creating a cus-tomized personal image that expresses a person’s sense

of identity.10,11 The main focus of his work was on painting human figures, and he studied the visual language of the face to create paintings with more realistic expressions

He gave a great boost to the development of Visagism with the association of visual expression of facial traits, given by lines, shapes, and colors, to the archetype theory coined by Carl Jung.12 Such association suggests that fa-cial traits generate sensations that influence the way a person is perceived, or that a quick observation of a face creates a remarkable first impression.13

Archetypal Symbols

The last years of Jung’s life were dedicated to research of different cultures and civilizations worldwide and establish-

ing links between occidental rationalism and oriental

mys-ticism He observed that certain symbols and images have

been used in all cultures with the same meaning Jung

coined the term “archetypal symbols” to define these

im-ages.His amazing book, Man and His Symbols,12

introduc-es some universal symbols in all culturintroduc-es, from all timintroduc-es,

regardless of background, ethnicity, religion, and

geo-graphic location Consider the universal meaning of the

lines represented in Fig 1

In his work, Hallawell10,11 considers that facial types, with their specific geometric configurations, represent arche-typal symbols that are automatically recognized by the observer’s brain, generating striking emotional impressions

of the observed individual Thus, according to Hallawell, visual expression of the face, from its geometric typology, would be intrinsically related to the sense of personal iden-tity (Figs 2a and 2b)

1

2b

Fig 1 Universal visual language: Vertical lines represent strength, power; inclined lines represent dynamism;

rounded lines represent suavity, delicacy; and horizontal lines represent stability and calmness.

Fig 2a The artwork of Philip Hallawell Visual expression of the face, from its geometric typology, would be

intrinsically related to the sense of personal identity

Fig 2b Four basic facial types ( left to right: strong, dynamic, delicate, calm) according to the theory of archetypal

and personal expression.

2a

considered the father of Western medicine, each human

being is an odd mixture of characteristics of four distinct

temperament types—choleric, sanguine, melancholic, and

phlegmatic—and each person can identify with one or two

more dominant temperaments Below are the main

behav-ioral psychological characteristics of each temperament:

• Choleric: dominant, determined, objective, explosive,

in-tense, leader, passionate

• Sanguine: extroverted, communicative, enthusiastic,

dy-namic, expansive

• Melancholic: introverted, organized, perfectionist, artistic,

abstractive, timid

• Phlegmatic: diplomatic, pacifist, mystic, spiritual,

con-formist, discreet, tending to submission

The present authors decided to rename these

tempera-ments using their own nomenclature to represent the

es-sence of each Thus the term “choleric” was replaced by

strong, “sanguine” by dynamic, “melancholic” by delicate,

and “phlegmatic” by calm.8

Such an approach has facilitated communication with

patients, since terms such as “choleric” or “melancholic”

were usually not well accepted or understood by them The

new terms also establish a direct association with the smile

design types described below

Visual Language

Each type of color, line, or shape has a specific emotional

meaning Primary colors and lines represent the most

ba-sic elements of visual language The latter can be divided

into straight lines and curves, the straight lines being

subdivided into vertical, horizontal, and inclined lines The

emotional expression of those lines depends on their

rela-tionship to the law of gravity.14 Horizontal lines, because

they conform to gravity, express stability, passivity, and

calmness, while vertical lines represent the movement of

the point against gravity, expressing strength and power,

just as inclined lines arouse the sensation of instability,

es dynamism, the oval expresses delicacy, and the square expresses stability and immobility by the balance between its vertical and horizontal elements (Fig 3) These basic shapes can be observed in the facial contour, as well as in the shapes of the central incisors and three-dimensional configuration of the dental arrangement—thus the incisal silhouette (Fig 4)

For Hallawell, through their own emotional meaning, lines and forms can be associated with temperaments, so that rectangular shapes as well as straight vertical lines have expression compatible with the characteristics of the choleric (strong) temperament, since the inclined lines and triangular shapes relate to the sanguine (dynamic), round-

ed lines and ovoid forms to the melancholic (delicate) type, and horizontal lines and circular forms to the phlegmatic (calm) temperament

VISUAL IDENTITY OF THE SMILE (VIS)

The visual language knowledge applied to the main pressive elements of smile design, such as dental shapes, incisal edge, interdental ratio or dominance, and 3D posi-tioning of the teeth in the arch, determined four smile de-sign types with primary expression (Fig 5):

ex-• Strong: composed mainly of rectangular dental shapes, strong dominance of centrals and canines on lateral inci-sors (radial symmetry), as well as plane incisal edge and rectilinear 3D dental positioning on the arch in occlusal view

• Dynamic: triangular or trapezoidal dental shapes, standard dominance, inclined incisal edge, and angled 3D dental positioning on the arch

• Delicate: oval dental shapes, medium dominance, curved incisal edge, and standard 3D dental positioning

• Calm or Stable: smoothly rounded square dental shapes, weak dominance (current symmetry), horizontal incisal edge, and 3D rectilinear or standard dental positioning

on the arch

4

5

Fig 3 The combination of lines generates the most basic forms, transferring to them their own expressions.

Fig 4 These basic shapes can be observed in the facial contours of the natural dentition, especially the shape of

the incisors.

Fig 5 Such drawings, from their primary expression, are visual representations of the four temperamental types

From top to bottom: strong, dynamic, delicate, calm

6b

6c

Sciences such as cognitive psychology, biology, and neuroscience have uncovered the influence of facial traits and temperament on the constitution of identity, consider-ing them as distinct elements that interact synergistically and constantly during the life of each person, defining their uniqueness For a better integration in the individual con-text of each dental patient, esthetic rehabilitations must go beyond the established esthetic rules, including informa-tion coherent with the facial typology and personality The facial configurations of each individual present themselves

as a unique combination of distinct traits

Through the large number of smile design elements (such as incisal edge, dominance, and dental axis), as well

as shapes as sub-elements (such as morphological details

of each tooth), it was necessary to establish, based on the dental scientific literature, which should be determined by the facial typology and which could visually represent the unique personality of each patient, beyond their personal preferences and expressions (Figs 6a to 6e)

For standard practice, reproducible and accessible to all professionals, a concept for smile design customization was elaborated by Paolucci et al.9 Called “Visual Identity of the Smile” (VIS), it developed from the association of differ-ent knowledge bases, such as esthetic and functional den-tal fundamentals, artistic visual language, facial recognition, and still personality typology For the objective application of this concept, the Rebel software program was developed

Visualizing the Final Result at the Beginning

Prior to initiating any treatment, it is necessary to visualize the desired outcomes It then becomes possible to formu-late the steps required to achieve this result.15 This visual-

and tooth axis (red) In order to create the individualized smile, the combination of the above lines, line angles, and curves must

be meticulously chosen, and will significantly differ from patient

to patient The algorithms of the Rebel software select the ideal setup out of these endless possibilities, based on the facial perception and personality of the individual patient.

ization already creates a lot of advantages A “direct

mock-up” is the ideal way of communicating with the

pa-tient regarding the final result However, instead of trying

many different design options while working with the

mock-up, which is currently being done intuitively, the dentist

will already have an imaginary frame with which to work

The Rebel Software

The Rebel software is able to perform facial reading and

personality assessment, evaluate a patient’s personal

pref-erences, and convert that information into mathematical

language Through preprogrammed algorithms, initially a

two-dimensional smile design is created The software is

capable of automatically transforming this 2D smile design

into a 3D customized model The model generation is

per-formed by a custom 3D library, developed specifically for

Rebel Simplicity Every model is personalized according to

the proposed teeth configuration.16

The Rebel system is actually a virtual lab that converts

the 2D design into 3D and creates a digital wax-up

imme-diately The 2D is created by relating the facial perception

and the personality of the patient to the smile design, by

applying algorithms for computing the optimal combination

of the incisal silhouette, tooth axis, dominance of the

cen-trals, and the combination of individual tooth shapes out of

thousands of possibilities It may sound complicated;

how-ever, it is the simplest way of getting one of the best 3D

digital wax-ups possible In other words, Rebel is a very

sophisticated artificial intelligence–based software;

how-ever, it provides great simplicity to the end users—dentists

and dental technicians

CASE PRESENTATION:

REBEL WORKFLOW

The patient in this case was not comfortable with the look

of her smile Her chief complaint was the spaces between her teeth and secondarily her gummy smile A negative smile line and somewhat narrow buccal corridors were also visible (Figs 7 and 8)

After completing the following three simple steps, all the necessary information is transferred to the Rebel digi-tal laboratory:

1 Digital scanning of single mock-up on a central incisor

2 Full-face photography protocol

3 Simple questionnaire

Single Central Mock-up and Intraoral Digital Scanning

Single Central Mock-up

A composite mock-up is first created on one (or two) of the central incisors in order to identify the incisal edge position vertically and the position of the facial surface buccolin-gually This is no different than making any direct mock-up;

Fig 7 Patient is uncomfortable with the look of her smile Her chief

complaint is the appearance and the small spaces between her

teeth She also has narrow buccal corridors.

however, the design of this mock-up for Rebel does not

require the usual detail, meaning that the dentist does not

need to choose the shape of the teeth (square, triangular,

rounded, etc), the angulation of their axis, surface texture,

etc The Rebel artificial intelligence–based software will

provide the details of the new smile design according to the facial perception and personality of the patient This will allow any dentist at any level to start working with mock-ups and end up with high-level wax-ups (Fig 9)

Stable bite

Fig 8 When analyzed carefully, a negative smile line can be observed, with the central incisors being shorter in length than the

canines.

Fig 9 Treatment of every

esthetic case should start by

defining the incisal edge

position of the maxillary

central incisors A composite

mock-up on one (or two) of

the central incisors identifies

the incisal edge position

(vertically) and the position

of the facial surface

(bucco-lingually) This simple

mock-up is digitally 3D

scanned together with the

full maxillary arch.

Rebel

Intraoral Digital Scanning

Once completed, the mock-up on the central(s) is digitally

scanned with any intraoral scanner that can create an STL

file Most intraoral scanners already automatically convert

the 3D scanning to an STL file

If the dentist does not have an intraoral scanner in the

dental practice, an analog impression of the maxilla

(pref-erably with the direct mock-up done on the centrals) can

be made and sent to the nearest dental lab (any lab that

has a CAD/CAM machine will have a digital scanner) The

dental technician can digitalize this impression for the

den-tist and upload the STL file into Rebel to complete your

order using the provided link

The Full-Face Photography Protocol

The software needs to have five specific full-face

photo-graphs for facial recognition of the patient and to relate the

3D intraoral digital scan to the facial features These five

photographs, shown in Fig 10, are described below

Full-Face Rest Position

This photograph is for the automatic facial recognition part

of the software, and part of the new Rebel smile design will

be based on this facial perception of the patient

Techni-cally it is very important that the forehead and the ears of

the patient are visible If the patient has long hair, it needs

to be away from the face The patient’s head must be

up-right (not tilted to the up-right, left, or up/down), the eyes

pref-erably positioned parallel to the horizon, and the lips apart

The software automatically checks the required full-face

image and, if it is not acceptable, the dentist will receive an

immediate message to replace it

Full-Face Smiling

Keep the patient in the same position, with the eyes open

and parallel to the horizon, and the head upright This

time ask the patient to keep the lips apart with a soft

and the displayed arch position to the lower lip line The first, and the easy choice, is to keep the patient in the same position and ask him/her to bend the face forward 45 degrees while maintaining a full smile Or the dentist can have the patient lie on the dental chair in a supine position, move to 12 o’clock position, and maintain a full smile; the dentist can then take the photograph from 45 degrees

Full-Face Open Bite

The patient should be asked to hold the full-mouth tors, again positioning the eyes parallel to the horizon, holding the head upright, and keeping the teeth (maxillary and mandibular) separated and the occlusal plane parallel

retrac-to the horizon

Full-Face Retracted Occlusion

The same protocol above should be repeated; however, this time the teeth should be closed

Questionnaire

The interview, which will indicate the character and ality of the patient, is completed in less than a minute through a questionnaire in the software It provides the pri-mary and complimentary character of the patient Because the temperamental type of each individual is defined by a unique combination of characteristics of the four main temperaments and a precise and practical evaluation of it,

person-it is necessary to apply a specific questionnaire

The optimal tooth shape is determined with the help of the interview The questionnaire is based on popular psy-chological tests for personal self-assessment The first question is an adapted test by Dellinger17 and the other three questions concern personality traits based on the theory and questionnaire by Eysenck and Eysenck.18 The questionnaire is checked by a computer algorithm to clas-sify the patient’s personality Based on the data from the interview, a software algorithm automatically calculates the temperament, as perceived by the patient The tempera-ment is a combination of strong, dynamic, delicate, and

calm After this procedure, the dentist and/or technician

will have the full idea of the facial perception and

personal-ity of the patient (Fig 11)

As the dentist is about to send the three mandatory files

to the Rebel digital laboratory, he/she will also be asked to

describe any specific designs regarding the clinical case,

such as the buccal corridors, imperfections, intensity of the

surface texture, etc, or to choose some of the optional

fea-tures provided if needed (Fig 12)

Rebel Digital Laboratory

Once all this information is sent to the Rebel digital

labora-tory, the software will immediately create the new Rebel

smile design by first converting it to 2D format and into the

3D design While doing this, the Rebel software will decide

on the main elements of the new smile design, such as the

incisal silhouette, dominance of the centrals, tooth axis,

and arch form, as well as choose the ideal individual tooth

shape that would be the most natural relative to the tient’s facial perception and the personality the patient wanted to be perceived

pa-Rebel has a very large digital tooth library, composed of the ideal forms of natural teeth and wax-up designs of top dental technicians In addition, the software selects the two main shapes (ie, from rectangular, triangular, ovoid, square) that match with patient’s facial perception and personality, and depending on the percentages, it blends and molds the selected two main shapes into the ideal forms For ex-ample, if the overall perception of the face and personality

is a combination of 70% dynamic and 30% delicate, it lects the ideal triangular and ovoid shapes and blends them into each other with a combination of these percent-ages, the main silhouette of the teeth being triangular but with the saddle appearance of ovoid as well

se-Once this design is automatically placed over the tally scanned original maxilla of the patient and rendered,

digi-an immediate STL file of this new Rebel digital wax-up is formed (Figs 13a and 13b)

Fig 10 The full-face photography protocol Five photos need to be taken: (1) lips at rest, (2) smiling, (3) 12 o’clock position, (4)

retracted open, (5) retracted closed.