alessandroagnini
`andreaagaiai
`
`CO—AUTHOR
`_
`.
`christianaaaaehman
`
`
`
`fllfilTflL [IENTHL
`BEVBLHTIUN
`v THE LEHRNINE CURVE
`
`
`
`Align Ex. 1014
`Align Ex. 1014
`U.S. Patent No. 9,962,244
`US. Patent No. 9,962,244
`
`0001
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`
`aieesaridroagfiiai
`andreaagriifii
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`i DIGITHLDENTHLHEVULUTIDN /
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`I
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`THE LEHHNINB EUHVE
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`v
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`'Ij‘-‘/'.;
`iViiian,Berlin,Chicago,Tokyo,London, Q
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`Paris, Barcelona, Beijing, isiaribul,
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`Moscow, New Deihi, Prague,
`Sao Paulo, Seoul, and Warsaw
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`0002
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`6
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`Copyright © 2015 by Quintessenza Edizioni S.r.l.
`Via Ciro Menotti. 65 , 20017 Rho (Ml) Italy
`Tel +39.02,93180821 .. Fax number +39.02.93186159
`
`
`Email: into@quintessenzaedizioni.it
`www.quintessenzaedizioni.com
`
`ISBN:
`
`978—8874920174
`
`All rights reserved This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted
`in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of
`the publisher.
`
`Printed in ltaly
`
`0003
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`

`

`
`
`
`
`' TABLE or CONTENTS
`
`
`
`EHHPTEH
`
`EHHPTEH
`
`. New Technologies ...2
`
`A
`
`Introduction ...3
`
`Tradition vs innovation:
`
`What has changed? ...6
`
`Traditional protocol work flow ...7
`
`Technical work flow with
`
`CAD/CAM technology ...8
`
`Material selection and treatment plan
`sequencing ...12
`
`Zirconia ...20
`
`Zirconia literature review ...22
`
`Mechanical properties of zirconia
`ceramics ...23
`
`CAD/CAM technology for fabrication of zirconia
`abutments and frameworks for crowns and fixed
`
`dental prostheses ...23
`
`Considerations for using zirconia as a restorative
`material ...24
`
`Considerations for fixed implant restoration
`designs ...32
`
`erconia abutments _..33
`
`Recommended clinical protocols ...34
`
`References ...36
`
`Diagnosis
`and Communication ...40
`
`Smile analysis and esthetlc designs ...42
`
`initiating smile analysis: Evaluating facial and
`orofacial esthetics ...43
`
`Evaluating oral esthetics ...44
`
`Dentogingival esthetics ...44
`
`Digital Smile Design approach ...45
`
`DSD protocol:
`
`- Esthetic diagnosis ...47
`— Communication ...47
`- Feedback ...48
`
`- Patient management ...48
`- Education ...49
`
`DSD work flow ...49
`
`DSD concept goals ...53
`
`Smile design test drive ...57
`
`DSD Connect ...83
`
`The four DSD views “.84
`
`Conclusion ...85
`
`References ...87
`
`XIV
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`
`
`TABLE or CONTENTS '
`
`EHHPTEH
`
`EHHPTEH
`
`vThe Digital ImpreSSIon ...88‘ The Learning Curve ...120
`
`Digital impressions in the literature ”97
`
`The digital work flow .._100
`
`The fo intraoral scanner ...101
`
`Learning curve “.122
`
`Knife—edge preparation: A possibility with new
`materials? ...132
`
`Highlights of the system ...102
`
`Zirconia and new technologies ...134
`
`Important areas ..i107
`
`Areas of less importance ...107
`
`STEP I . Target area definition .. .107
`
`STEP 2‘ General scan ...107
`
`STEP 3. Checking and finishing phase ...107
`
`Conclusion ...114
`
`References ...116
`
`New customized abutment design: Zirconia inside
`laminate (ZIL) ...138
`
`Is it possible to apply ZIL in the anterior
`dentition? ...142
`
`Soft tissue displacement: Indications, purpose,
`and techniques ...151
`
`Impression objectives ...155
`
`Implants and digital impressions ".155
`
`Surgical procedure ...158
`
`Tooth extraction ...159
`
`Implant placement ...160
`
`Trabecular Metal Material “.160
`
`Gap management ...161
`
`Provisional restoration fabrication ...162
`
`Connective tissue graft augmentation ...163
`
`Bone graft augmentation ...165
`
`Digital impression taking ...167
`
`Technical work flow ...167
`
`Protocol for overbuilding
`of the socket site ...174
`
`CAD/CAM implant abutments:
`The true advantage ...186
`
`Titanium or Zirconia abutments:
`What is the rationale? ...188
`
`References ”.193
`
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`
` ' TABLE or CONTENTS
`
`
`
`EHHPTEH
`
`EHHPTEH
`
`
`
`Treating Complex Cases
`with New Technologies and
`Materials ...198
`
`'The New Digital
`
`Possibilities ...254
`
`Treatment planning in complex cases ...205
`
`Patient complaint and history .. .207
`
`Preliminary tests and treatment ...207
`
`Diagnosis and treatment plan ...208
`
`Monolithic zirconia: Why and when ...259
`
`fo Zirconium Effect 2.0 Multilayer ...262
`
`Combining clinical experience: Monolithic
`
`zirconia crowns and digital impressions fora
`predictable restorative alternative ...263
`
`Surgical phase ...210
`
`Preliminary healing time ..266
`
`Monolithic zirconia and intraoral scanner:
`Predictable for complex rehabilitations’? ...270
`
`Cementation: Finalization of the prosthetic
`rehabilitation ...286
`
`New implant materials ...287
`
`Trabecular Metal implant rationale ...292
`
`Definitive prosthetic phase ..296
`
`References ...302
`
`Immediate provisional restoration ...211
`
`Definitive restoration work flow ...212
`
`Advantages of three-dimensional
`dental imaging ...220
`
`Surgical phase ...224
`
`Prosthetic phase ...227
`
`Definitive restoration: The role of digital
`dentistry ...229
`
`Scanning strategy:
`A critical step for success ...234
`
`Passive fit ”.248
`
`References ...250
`
`XVI
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`TABLE or CONTENTS I
`
`EHHPTEH
`
`EHHPTEH
`
`‘ Lithium Disilicate ...306 .
`
`Lithium disilicate: Literature review ...307
`
`The Immediate Digital
`Future ...344
`
`Digital systems ..308
`
`Clinical applications ...310
`
`Cementatlon operational protocol ...316
`
`Implant abutment: Selection criteria ...323
`
`References ...342
`
`The future of digital dentistry: New technology
`and dental team: Partners in success ”.345
`
`The digital challenge: Saving the patient’s time
`without losing quality in the definitive
`restoration ...347
`
`Digital and implant dentistry: Standard of
`patient care ...355
`
`The three—step protocol:
`- Appointment 1 : Implant surgery
`and scanning ...356
`
`- Appointment 2: Re-entry “.356
`
`- Appointment 3: Delivery ..358
`
`Fully digital restorative work flow ...370
`
`The digital articulator ”.376
`
`Digital provisional restoration ...379
`
`Future is now: The importance of keeping the
`dental team up—to—date W387
`
`PMMA: A new restorative solution ...396
`
`Conclusions: Anticipating the future ._.396
`
`References ...398
`
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`f
`
`
`THE DlGlTAL IMPRESSION I
`
`I CHAPTER 3
`
`
`
`
`
`for fabrication of
`technology (DDT)
`Digital dental
`dental
`restorations,
`including computer—aided de-
`
`(CAD/CAM),
`sign/computer—assisted manufacture
`has been in development since the 1980s.1 its
`
`rapid expansion and incorporation into the field of
`dentistry has been documented since the beginning
`of 1990s.“2
`
`Currently present on the market are several diag-
`nostic digital software programs, for example, the
`Digital Smile Design (DSD) created and designed
`by Christian Coachman and lei0 Yoshinaga, digital
`tools to check functional parameters and define tooth
`shades, which in this era of esthetics are becoming
`more important every day; digital articulators and
`digital customized abutments; and computer—guided
`surgery that can be combined with a three-dimen-
`sional (3D) computed tomography (CD evaluation to
`provide a wealth of information to the surgeon before
`and after procedures. In the last few years, several
`software programs for digital impressions have been
`developed, playing an important role in the transi-
`tion from conventional fixed prosthodontics to DDT
`
`because they represent one of the very last steps to-
`ward fully digital prosthetic fabrication, which is the
`goal of modern dentistry. The intraoral impression,
`indeed, is the first means of communication between
`clinician and technician.3
`
`impression devices have been intro-
`Digital dental
`duced to the profession, potentially eliminating the
`need for taking conventional impressions for crowns
`and fixed prostheses, The direct acquisition systems,
`which have been continually improved, are less in-
`vasive, quicker, and more precise than conventional
`methods. Moreover,
`traditional protocols
`require
`
`many critical steps that can be skipped when taking
`a digital impression.
`In fact,
`this technique can reduce chair time for
`
`procedures such as tray selection, cast setting time,
`disinfection, and transportation to the laboratory.
`in
`addition,
`the digital
`images can be easily stored.
`These emerging new digital concepts are creating
`
`a growing interest among dentists, causing them to
`think about the possibility of changing their impres—
`sion techniques“!5
`
`89
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`

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`
`
`
`I CHAPTER 3
`
`Fig 1. The digital dental
`revolution. The goal of modern
`dentistry is to create a completely
`digital work flow.
`
`r
`
`Some clinicians face the dilemma of wanting to keep
`
`up with the technologic advances in the profession
`while feeling unsure about embracing the digital im-
`pression technique and the related in—office milling
`of restorations (Fig 1).
`Benefits of the digital
`sented as:
`
`impression have been pre-
`
`Improved patient acceptance
`1.
`2. Reduced distortion of impression materials
`3.
`3D preview of the preparation
`4. Potential cost reduction and time effectiveness4
`
`Digital impressions for implant rehabilitations (Fig 2)
`would allow for:
`
`1. Virtual assessment of the implant prosthetic
`space
`
`2. Evaluation of depth of restorative margin
`3. Configuration of the emergence profile before
`
`proceeding with laboratory steps6
`Digital
`impressions have been used successfully
`for a number of years in orthodontics with soft-
`
`ware such as iOC/OrthoCAD (Cadent), OrthoPlex
`(Dentsply), SureSmile (Orametrix), and RapidForm
`(EMS). The introduction of the first digital
`intraoral
`scanner for restorative dentistry was in the 19803
`by a Swiss dentist, Dr Werner Mormann, and an
`Italian electrical engineer, Marco Brandestini, who
`developed the concept for what would be introduced
`
`
`
` a‘b
`
`
`
`
`0010
`
`in 1987 as Cerec (Sirona), the first commercial CAD/
`CAM system for dental restorations?7
`Since that time, research and development sectors
`at many companies have improved their technology
`and created in-office intraoral scanners that are in-
`
`creasingly user—friendly and produce preciselyfitting
`dental restorations. These systems are capable of
`capturing 3D virtual images of tooth preparations;
`from such images, restorations may be directly fab-
`ricated (using CAD/CAM systems), or they can be
`used to create accurate master casts for fabrication
`
`laboratory.1 Today
`of the restorations in a dental
`there are 11 intraoral scanning devices for restor-
`ative dentistry available worldwide; four are made
`in the United States; two in Israel; two in Germany;
`and one each in ltaly, Switzerland; and Denmark.
`Generally speaking, such scanners try to overcome
`the problems and disadvantages of the traditional
`impression fabrication process, such as instability of
`the impression, pouring of plaster, laceration of the
`margins, and geometric and dimensional discrepan-
`cy between the cast and the impression.
`The main benefits of the use of these devices are
`
`precise casts/models, creation of 3D archives
`and surgery simulation, and a simplified process.
`Existing devices are driven by several noncontact
`optical technologies, such as confocal microscopy,
`optical coherence tomography, photogrammetry,
`active and passive stereovision and triangulation,
`interferometry, and phase—shift principles. Basically,
`all of these devices combine some of the cited im-
`
`aging techniques to minimize the sources of disturu
`bance related to scanning inside an oral cavity, eg,
`optical features of the target surfaces (translucency
`and the different reflectivity of the target materials
`such as teeth, gingiva, preparations. and com—
`posites), moisture, and random movements. Also,
`several types of structured light sources and optical
`components are used.8
`
`Commercially available digital systems for the den-
`
`tal office are commonly divided into two categories:
`digital impression systems and chairside CAD/CAM
`
`systems. Both types must be able to accurately re-
`cord the intraoral condition on a computer data file
`with a scanner or camera.
`
`0010
`
`

`

` THE DlGlTAL wreaessrorfl
`
`it is what the system accomplishes after recording
`the data file that distinguishes them:
`
`0
`
`impression systems are designed to
`Digital
`electronically transmit the recorded data file to
`the dental laboratory for restoration fabrication.
`Once dental laboratories have downloaded the
`
`tile, they can have casts processed from it. Any
`conventional
`laboratory process can be used
`to fabricate the restoration once the laboratory
`
`receives the processed casts. Alternatively. the
`dental laboratory can use the transmitted data
`file in a CAD program to create a tull~contour
`restoration or coping that can be refined on the
`
`processed casts. Some of the most common
`examples of digital impression systems are the
`Lava Chalrside Oral Scanner (00.8.; 3M Espe),
`
`the iTero system (Cadent), the fo system (fo),
`and TRlOS (3Shape). This expedites the overall
`work flow, resulting in delivery of the definitive
`restoration in a shorter time span compared
`with the traditional approach (Figs 3 to 5).
`
`The Cerec Acquisition Center (AC; Sirona) and
`E4D Dentist system (E4D Technologies) are the
`
`
`
`Fly 2. Detail of the position of the lens of
`the intraoral scanner during scanning for a
`provisional restoration.g
`
`Figs 3 in 5. Lava, iTero, and TRlOS are
`some of the most common examples of
`digital impression systems.
`
`Fig 6. Cerec AC is one of the two available
`chairside CAD/CAM systems.
`
`s...‘
`
`two available chairside CAD/CAM systems.They
`
`can complete all three steps of the imaging.
`design, and milling process in the dental office
`to fabricate tullrcontour restorations within the
`
`time span of a single appointment. Both of them
`have manufacturer-specific software programs
`
`that permit the production of single-tooth ce-
`ramic or composite inlays, onlays, veneers, and
`crowns. They also offer the option to be used as
`
`purely digital impression systems. The choice to
`adopt one method or the other depends on the
`organization of the dental office and the type of
`initial investment that is intended.
`
`
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`0011
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`

`
`
`
`I CHAPTER 3
`
`
`
`
`
`Figs 7 and 8. Taking a good
`impression is one of the most
`crucial steps of the clinical
`work flow.
`
`7"
`
`in fixed prosthodontics, an accurate and precise
`
`impression is one of the main requirements for
`obtaining a proper and long—lasting restoration.IO
`When discussing digital
`impression taking com-
`pared with the conventional approach, an argu-
`ment is always made that the latter is more precise
`and that there is a mandatory and time—consuming
`
`learning curve involved in learning to use the new
`digital tools.
`However,
`it is important to note that the conven-
`tional technique also presents many difficulties and
`involves a learning curve to avoid all the pitfalls.H
`In fact, a recent literature survey conducted in the
`UK showed that many impressions judged to be
`“acceptable" by dental laboratory technicians are
`not; according to Storey and Coward, 44.2% of
`the intraoral recordings would not be satisfactory
`due to the presence of imperfections at the level
`of the prosthetic preparations.12 Careful evaluation
`of the traditional impression work flow reveals that
`the many steps involved are sources of possible
`inaccuracies and how it is, once again, critical to
`
`have a protocol to follow step by step in order to
`help the operator reduce mistakes13 (Figs 7 and 8);
`The clinician should ensure that the impression
`
`includes all the necessary information, is clearly
`
`is
`readable, provides details of the preparation,
`free of bubbles and tears, and covers all of the
`elements involved.
`
`In a study by Samet et al,14 an assessment was
`made of 193 impressions sent to 11 different
`laboratories. Factors such as the material, the
`
`technique, the type of impression tray, and the
`number of elements prepared were recorded,
`and then the quality of the impression technique
`for the construction of
`fixed prostheses was
`assessed, describing the frequency of clinical
`errors and analyzing the correlations between
`the factors involved (Tables 1 and 2).
`The results can be summarized as follows:
`
`Lack of precision
`0
`- Removal of material from the tray
`
`Putty exposure in two-stage impressions
`-
`Taking an impression is,
`in fact, probably the
`most critical step in the process of creating res—
`torations that fit.
`
`A perfect impression should:
`0
`Provide an exact duplication of the clinical
`situation
`
`-
`
`0
`
`Include a complete, void—free, and accurate
`reproduction of the margins
`Be correct on the first attempt
`
`92
`
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`

`
`
`THE DIGITAL IMPRESSION l
`
`'Type oi void
`
`Causes
`
`Solutions
`
`Underuse 0t light—body material and appearance
`of a gap.
`
`Place an adequate quantity of material in critical areas.
`
`Localized on the lingual
`and buccal surfaces
`Store the product at the indicated temperatures to
`High environment temperature and premature
`preserve the viscosity and hardening characteristics.
`light curing.
`Use an individual tray.
`
`Localized on the mesial
`Low hydraulic pressure for the flow and adaptation
`and distal surfaces
`Use a combination putty/lightebody technique or a
`of the material to the proximal surfaces.
`two—phase technique.
`incorrect manual mixing of the material with air
`trapping.
`
`Repeat manual mixing.
`
`Maintenance of the dispenser tips or syringes
`dispensed in.
`
`
`
`
`impression materials to increase the working time.
`
`Multiple, randomly
`distributed
`
`Localized on the
`preparation margins
`
`Incorrect automatic dispensing (tip not in the
`material).
`Contamination by moisture. chemicals, or
`crevicular fluids.
`
`Use the double-cord technique to improve the
`Localized in the
`displacement and absorption of moisture.
`suicular area
`Rinse thoroughly and dry.
`inadequate hemostasis.
`incorrect technical delivery of the light—body
`material: the start and end points of the material do
`not meet.
`
`Complete delivery of the light-body material 360
`degrees around the abutment.
`
`Error in setting times: lack of integration of light—
`body material in some areas.
`
`Use slow-setting materials in complex cases; cool
`
`
`
`Table 1. Causes and so utlons for common defects (voids) that could be found during conventional impression taking
`
`Solutions
`
`
`
`Prevent movement of the tray during the impression.
`Increase the separation ot the material before relining
`the impression.
`Use an custom tray or carefully select a standard tray.
`Try in the tray and determine how to correctly insert it
`before proceeding with the impression.
`Ask the patient to keep the mouth open during the
`
`Protrusion/projection of
`material (from the surface ‘
`oi the impression to the
`hollow areas contact
`between the Impression
`tray and dental elements/
`preparations,
`
`Movement/sliding of the tray before complete
`hardening of the material.
`Incorrect repositioning of the tray during relinlng
`in the putty wash of the twophase technique or
`inappropriate size or shape of the selected tray.
`Inaccurate insertion of or excessive thrust on the tray.
`Patient grinding with the tray between the arches.
`
`
`impression. Lacerations/tears
`
`
`
`Removal of the material before complete
`hardening.
`Accentuated undercuts.
`
`Use a custom tray.
`Use a combination putty/Iight—body or two-phase
`technique.
`With silicone impressions, do not directly touch the
`Inadequate displacement of the gingivai margin
`material with the gloves
`(intrasulcuiar area too tight).
`Contamination
`Use a high-tear—strength material.
`Correctly displace the soft tissue.
`Use of a material with low tear resistance.
`
`Delaminations
`
`Lack of coordination of the curing time between
`the high and low-viscosity materials.
`Contamination between the delaminated layers.
`High ambient temperature.
`
`Follow the recommendations of the manufacturer
`regarding processing times.
`Perform maneuvers for control of hemostasis and
`retraction; prevent contamination between heavy-
`and lightebody layers.
`Cool the impression material.
`
`Table 2. Causes and solutions for other common detects found in conventional impressions
`
`93
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`

`

`
`
`
`
`‘ CHAPTER 3
`
`
`
`
`compliance with guidelines are not understood.i6
`
`
`Figs 9 to 11. Problems
`can occur and sometimes
`cannot be resolved, such
`as incomplete hardening
`of the material, exposure
`of the tray, an improper
`mixture of light- and
`heavy—body material, or
`absolute inaccuracy of
`details.
`
`Figs 12 to 14. Poor bond
`between the tray and wash
`material, lack of impression
`details, and inappropriate
`methods of storing and
`transporting are causes of
`lack of accuracy in the final
`conventional impression.
`
`The various clinical decisions made during the
`protocol are essential for the accuracy of the
`impression, such as:
`
`9 The choice of tray and adhesive in relation to
`the material used helps to prevent detach-
`ment of the material from the tray;
`in fact,
`even removal from the oral cavity may cause
`problems of deformation.
`
`0
`
`0
`
`The quality of the impression material cho—
`sen can greatly affect the surface of the
`hardened plaster.
`
`Prior to casting, it is necessary to eliminate
`the anatomical undercuts, allowing easy de-
`tachment of the cast without deformation of
`the impression.15
`
`__
`
`The most common clinical errors can be identi-
`'7 fied as incomplete reproduction of the intraoral
`situation, voids and tearing at the preparation
`margins, wash material displaced 0r washed
`
`0014
`
`away from the preparation area, distortions, de-
`fects caused by blood or saliva, exposure of the
`tray, incomplete setting of impression material,
`poor bond between the tray and wash material,
`and discrepancies on the cast (Figs 9 to 11).
`Also, what is done after a conventional impression
`is taken might be a cause of inaccuracies; inade-
`quate disinfection may affect surface quality, detail
`reproduction, and dimensional
`stability.
`in fact,
`before casting and/or providing the impression to
`the dental
`technician, the office must have spe-
`cific protocols for disinfection. The manufacturer's
`instructions should be consulted to determine
`which disinfection products will not damage the
`impression. Unfortunately,
`studies have found
`that the percentage of clinicians who perform this
`procedure with care is low. in some countries, this
`figure is as low as 57%, butthe factors that prevent
`
`I
`
`0014
`
`

`

`THE DlGilTAL IMPRESSION ‘
`
`room temperature
`Storing the impression at
`avoids deformations. A low storage temperature,
`
`for example, prolongs the setting reactions and
`changes the viscosity of the material, affecting
`the surface quality (detail reproduction) and di—
`mensional stability.
`
`it is always recommended to rinse the polyether
`impressions with water and dry them before
`sending them to the laboratory, avoid putting
`them in a bag along with alginate impressions,
`and store them away from direct sunlight to pre-
`vent a reduction in the impression quality.
`
`
`
`
`Transporting the impression to a commercial
`dental laboratory subjects an impression to sig—
`nificant variations in temperature. A temperature
`variation from 4°C to 40°C has been shown to
`result in a i— to iB—mm dimensional change.17
`
`Moreover. during the time between securing an
`impression and the pouring stone cast, the am—
`bient temperature, the surface wettability, and
`disinfection procedures may result in additional
`distortionmiig
`
`Cast production is another step that might lead
`to uncontrolled expansion of the cast, bubbles,
`and fractures. It
`is obvious that if these imper—
`fections were located on critical areas, such as
`
`the preparation margins and the axial and oc-
`clusal surfaces of the abutments, the restoration
`
`would not fit properly. There are, in the tradition—
`al approach, different
`impression techniques
`
`classified according to the timing with which the
`materials are used and the consistency of the
`materials themselves.
`
`It is important that the dentist has an in—depth
`and detailed Knowledge of the various tech-
`niques order to move toward the most suitable
`one for the clinical situation at hand (Figs 16
`
`and 17).
`
`Figs 15 and 16. Examples of
`inaccuracies in the production of
`the plaster cast include voids in the
`plaster cast, giving the appearance
`of a golf ball, and voids at the finish
`line and on the incisal edges of the
`abutment.
`
`
`
`0015
`
`0015
`
`

`

`l
`
`1 CHAPTER 3
`
`
`
`
`Ensure uniform and homogenous mixing of
`material (ie, using automatic mixers).
`Fill tray sufficiently with impression material
`without trapping air bubbles.
`
`Use gloves that do not inhibit the setting of
`the impression material.
`
`figsI1to19.Hnm
`polyether impression to
`restore a case with ceramic
`veneers.
`
`V
`
`the impression is
`the main roles of
`One of
`to record the details of
`the preparations and
`neighboring structures in their entirety. eg, over-
`preparation in case of shoulder finish lines and
`
`to record the architecture of the gingival tissues
`(Figs 17 to 21). That is why taking an accurate
`and detailed final impression is a crucial step in
`creating a successful prosthetic rehabilitation.
`Having a protocol for taking impressions is man-
`
`datory and should consider the following:
`1. Ensure healthy soft tissue at the level of the
`prosthetic abutment.
`
`2. Ensure adequate retraction of the marginal
`soft tissue with mechanical and/0r chemical
`
`if chemical agents are used,
`procedures.
`rinse and dry thoroughly.
`3. Choose an appropriate tray and viscosity of
`wash materials as well as proper working
`times (regular or quick) according to the im-
`pression technique and indications.
`
`4. Use a properly fitting, rigid, and sturdy im-
`pression tray.
`
`5. Thoroughly apply tray adhesive and let it dry
`appropriately (for at least 15 minutes) before
`taking the impression.
`
`10.
`
`11.
`
`12.
`
`13.
`
`14.
`
`96
`
`0016
`
`Have separate timers to check the working
`time (2 to 2.5 minutes) and the hardening
`time (5 to 6 minutes).
`Avoid air ent'apment during intraoral syring—
`‘ng of the wash material by immersing the tip
`'n the material.
`
`Apply contro led vertical pressure upon seat—
`'ng the tray to avoid contact between teeth/
`tissue and the bottom of the tray with a verti-
`cal movemert.
`
`
`
`
`
`Vlove the ligrt-body material into the gingival
`sulcus with a puff of air and cover all of the
`
`abutments w‘th the light-body material, start-
`'ng with the nonvital tooth preparations and
`implant abutments.
`Avoid any movements that could shift the
`position of the tray and lead to distortions.
`
`Stay within the working time of the tray and
`wash materials.
`
`0016
`
`

`

`
`
`THE DlGITAL |MPRESS|ON I
`
`
`
`
`
`Figs 20 and 21 . Final
`polyether impression for a
`complex periodontal case
`involving prepared teeth
`and implants.
`
`Fig 22. Digital
`impressions are as
`sensitive to blood and
`moisture as traditional
`impressions; therefore, soft
`tissues must be healthy.
`
`15.
`
`16.
`
`17.
`
`18.
`
`19.
`
`20.
`
`21.
`
`22.
`
`Use the correct protocol to remove the tray
`from the mouth, depending on where the
`abutments are located.
`
`When removing the tray from the mouth,
`avoid unilateral rotation.
`
`Verify that, on all surfaces, the tray does not
`show through the impression material, which
`would indicate that the tray came in contact
`with the hard or soft tissues and there will be
`
`an inaccuracy in that area.
`Make sure that the tray is not exposed, which
`would mean that the tray is in contact with
`the tooth structures or soft tissues and the
`information recorded would not be accurate.
`
`Check for proper blending between the tray
`and wash materials as well as a proper bond
`
`to the tray.
`Disinfect
`the impression according to the
`manufacturer’s instructions for use.
`
`After disinfection, rinse the impression with
`water and dry it before sending it to the lab.
`Exact brand of impression material and dis-
`infection protocol must be communicated to
`the dental laboratory.
`
`Digital impressions in the
`literature
`
`All digital impression systems and chairside CAD/
`CAM systems rely on the ability to accurately re-
`cord the intraoral data file, and there are a couple
`
`of principles that are common to all the cameras
`that significantly influence the outcome:
`1. Digital impressions are as sensitive to mois-
`ture contamination as traditional impression
`
`mm'mrfiqgmm—v—WW
`
`materials. Blood and saliva obscure the sur=
`
`face of the tooth and dentogingival margins
`from the camera and prevent an accurate
`
`the camera records
`recording. At best,
`the moisture as a false surface contour; at
`
`worst, no data is recorded where moisture
`has collected. in either situation, an accurate
`restoration cannot be fabricated.
`
`. A second principle is that inadequate man-
`
`agement and retraction of soft tissues may
`prevent visualization of the marginal areas,
`resulting in an inaccurate recording with the
`camera. As desirable as it may be to scan
`
`through soft tissues, this is not possible with
`current systems. Digital cameras can only re—
`cord data that is directly visible to the camera
`lens”20 (Fig 22).
`
`
`
`9%
`
`0017
`
`0017
`
`

`

`I l l l l l l l
`
`
`
`a digital impression demonstrated better internal fit
`compared with those fabricated from a conventional
`impression.
`
`More specifically, reviewing each retainer face, the
`digital impression showed better marginal and inter-
`nal fit at the premolar mesiai and molar distal faces.
`
`As for the efficiency, accuracy, and clin'cal viability
`of digital impressions for implant restorations, there
`have not been any standardized and andomized
`clinical studies. In this specific context, validation of
`DDT is paramount to understanding the impact of
`this new technology in terms of modifying well—es—
`tablished traditional protocols.
`
`implant dentis ry has be-
`During the last decades,
`come fully integrated into prosthetic patient treat—
`ment and dental reconstruction. The dertal implant
`'ndustry has started to develop tools that facilitate the
`
`
`
`use of intraoral scanners to make digital impressions
`of dental implants.
`
`Despite the deformation of impression materials‘3
`and the cast,”28 the work flow for conventional im~
`
`pression taking for implant restorations has proven
`‘tself in clinical practice?9
`
`The introduction of scannable impression copings,
`towever, now enables the use of intraoral scanners
`
`as an alternative to conventional impression taking.
`)el Corso et al30 showed in an in vitro study that
`'ntraoral scans could be a valid alternative to ana-
`
`
`
`
`
`' CHAPTER 3
`
`
`
`Fig 23. Clinical situation of
`central and lateral incisor
`preparations immediately
`before digital impression
`taking. Note the presence
`of fine powder on the scan
`area to bring uniformity to
`the differing reflectivity of the
`surfaces.
`
`Figs 24 and 25. Scannable
`impression coping in place
`on the study cast (Fig 24) and
`virtual model (Fig 25) from
`a digital impression (iTero).
`Reprinted from Lee and
`Gallucci24 with permission.
`
`Several studies investigated the efficiency and accu-
`racy of the digital impression in tooth-supported fixed
`prosthesesfil22 Recently more standardized and
`
`randomized studies have been published, for exam—
`ple, one by Syrek et al23 evaluating ceramic crowns
`produced from a totally digital process, which re-
`vealed that the crowns from intraoral scans featured
`
`significantly improved marginal fit and interproximal
`contact area compared with crowns fabricated from
`
`a silicone impression, while both groups performed
`equally well with regard to occlusion.
`
`at Bologna
`in 2011, Monaco and colleagues
`University25 performed clinical trials to test the ac-
`curacy of single all-ceramic zirconia crowns result»
`
`impression with active
`intraoral
`ing from a digital
`wavefront sampling technology by measuring the
`marginal and internal fits of the crowns and found
`
`that the single crowns obtained from the digital work
`flow presented enough accuracy to be used as an
`alternative to the traditional one.
`
`In 2013, Almeida e Silva et al26 published a compar—
`ative analysis of four-unit zirconia fixed dental pros-
`theses based on digital and conventional techniques,
`revealing that while both groups showed clinically
`acceptable marginal fit, frameworks fabricated from
`
`
`
`logue impression taking. A recent clinical study by
`Karl et al31 showed that the intraoral digitization of
`dental
`implants appears to be at least as precise
`as conventional impression taking and master cast
`fabrication using prefabricated transfer components
`and laboratory analogs.
`In their 2013 publication, Lee and Gallucci24 evaluat-
`
`ed the efficiency, difficulty. and operator’s preference
`
`
`
`
`
`98
`
`0018
`
`0018
`
`

`

`
`
`
`
`
`
`THE DIGITAL IMPRESSION I
`
`impressions compared with conventional
`impressions for single implant restorations. An in-
`teresting aspect of this study was that participants
`were dental students with no previous exposure to
`
`impression taking.
`implant
`conventional or digital
`This homogenous group allowed investigation of
`the efficiency of these impression techniques in an
`objective and nonbiased manner.
`This is of particular importance since results f