University of Iowa

Iowa Research Online Theses and Dissertations

Summer 2013

An in vitro evaluation of the marginal integrity of CAD/CAM interim crowns compared to conventional interim resin crowns Kwang Yong Kelvin Khng University of Iowa

Copyright 2013 kwang yong kelvin Khng This thesis is available at Iowa Research Online: http://ir.uiowa.edu/etd/4863 Recommended Citation Khng, Kwang Yong Kelvin. "An in vitro evaluation of the marginal integrity of CAD/CAM interim crowns compared to conventional interim resin crowns." MS (Master of Science) thesis, University of Iowa, 2013. http://ir.uiowa.edu/etd/4863.

Follow this and additional works at: http://ir.uiowa.edu/etd Part of the Oral Biology and Oral Pathology Commons

AN IN VITRO EVALUATION OF THE MARGINAL INTEGRITY OF CAD/CAM INTERIM CROWNS COMPARED TO CONVENTIONAL INTERIM RESIN CROWNS

by Kwang Yong Kelvin Khng

A thesis submitted in partial fulfillment of the requirements for the Master of Science degree in Oral Science in the Graduate College of The University of Iowa

August 2013

Thesis Supervisor: Professor Ronald L. Ettinger ! ! ! ! ! ! ! !

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Copyright by KWANG YONG KELVIN KHNG 2013 All Rights Reserved

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Graduate College The University of Iowa Iowa City, Iowa ! ! CERTIFICATE OF APPROVAL ___________________________ ! ! ! MASTER’S THESIS

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Measure Not the Work Until the Day Is Out and the Labor Done

Elizabeth Barrett Browning, Aurora Leigh

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ACKNOWLEDGMENTS I wish to express my sincere appreciation to Dr Ronald L, Ettinger, Thesis Committee Chairman and to Committee Members, Dr Steven R Armstrong, Dr David G, Gratton, Dr Terry Lindquist and Dr Fang Qian for their time and support. I will like to thank Delta Dental, Dr Shashikant Singha from Ivoclar Vivadent and Adam Quade from Patterson Dental for their financial, materials, equipment and technical support. This research would not have been possible without their help. Lastly, I will also like to acknowledge the following people for their valuable expert guidance. Research specialist Ms Maggie Hogan for helping me with the set up of the research, research manager Mr Jeffery Harless for his laboratory support and Specialist librarian Ms Christine White for her patience and encouragement. ! ! ! ! ! ! ! !

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Assessment of Reliability of the Marginal Discrepancy Measurements...... 53 Histological Evaluation of Samples ............................................................ 53 Question Number 1 ...................................................................................... 56 Question Number 2 ...................................................................................... 58 Question Number 3 ...................................................................................... 66 Question Number 4 ...................................................................................... 67 7!

5. DISCUSSION .............................................................................................. 70 Sample Size .................................................................................................. 71 Experimental Design .................................................................................... 71 Time Taken for Fabrication of Interim Crowns ........................................... 77 Strength of Study.......................................................................................... 77 Limitations of the Study ............................................................................... 78 Suggestions for Future Study ....................................................................... 79 6. CONCLUSION............................................................................................ 80 REFERENCES ............................................................................................................... 82 APPENDIX .................................................................................................................... 90

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LIST OF TABLES

! Table 1. Table of Materials .................................................................................................. 49 2. Mean Vertical Component of the Combined Facial and Lingual Marginal Discrepancies between CAD/CAM and Conventional Interim Crowns................ 56 3. Mean Horizontal Component of the Combined Facial and Lingual Marginal Discrepancies Between CAD/CAM and Conventional Interim Crowns............... 57 4. Mean Vertical Component of Marginal Discrepancy at the Facial Surface for the Different Types of Crowns ........................................................................ 58 5. Mean Horizontal Component of the Marginal Discrepancy at the Facial Surface for the Different Types of Crowns ........................................................................ 59 6. Mean Vertical Component of Marginal Discrepancy at Lingual Surface for the Different Types of Crowns.................................................................................... 60 7. Mean Horizontal Component of Marginal Discrepancy at the Lingual Surface for the Different Types of Crowns ....................................................................... 61 8. Difference Between the Mean Vertical Component of the Marginal Discrepancies at the Facial and Lingual Surfaces for the Different Types of Crowns ................. 62 9. Difference Between the Mean Horizontal Component of the Marginal Discrepancies at the Facial and Lingual Surfaces for the Different Types of Crowns.............................................................................................................. 63 10.Mean Depths of Penetration of Acid Fuschin After Thermocycling as a Percentage of the Crown for the Different Types of Crowns .................................................. 66 11.Correlation Between Dye Penetration and the Vertical Component of the Facial and Lingual Marginal Discrepancies ......................................................... 67 12.Correlation Between Dye Penetration and Horizontal Component of the Marginal Discrepancies at the Facial and Lingual Surfaces ................................. 69 A1. Results of Marginal Discrepancies and Dye Penetration for Cerec®/ Telio® Interim Crowns ...................................................................................................... 90 A2. Results of Marginal Discrepancies and Dye Penetration for E4D®/ Paradigm® MZ100 Interim Crowns ........................................................................................ 91 A3. Results of Marginal Discrepancies and Dye Penetration for Caulk® Resin Interim Crowns..................................................................................................................... 92 !

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A4. Results of Marginal Discrepancies and Dye Penetration for Jet® Resin Interim Crowns ..................................................................................................................... 93 A5. Re-measurement of Marginal Discrepancies in 12 Selected Interim Crowns ........ 94

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LIST OF FIGURES

1. Image of Lava® Scan ST (3M® ESPE) .............................................................. 4 2. Image of Everest® Scan Pro (Kavo®) ................................................................ 5 3. Image of Es1 (Etkon®) ..................................................................................... 5 4. Image of Procera® Forte (Nobel Biocare) ........................................................ 6 5. Cerec® In Lab (Sirona®) MC XL CAD/CAM Milling Machine ..................... 7 6. Image of Lava® CNC 500 (3M® ESPE) Milling Machine................................ 8 7. Image of Cercon® Brain (Degudent®) Milling Unit.......................................... 8 8. Image E4D® (D4D Technologies) Milling Unit .............................................. 9 9. Image of Digital Dental 4 – Axis (Creative Dental Laboratory) Milling Unit ....................................................................................................... 9 10. Image of Kavo® ARCTICA Engine ................................................................ 10 11. Image of HSC 20 Linear Milling Unit ............................................................FF 12. Image of the Prepared Dentoform® Model and a Silicone Putty. .................. 43 13. Stereolithic Cast of Dentoform®...................................................................... 44 14. Cerec® 3 System with the Cerec® Milling Unit ............................................ 50 15. E4D® System with the E4D® Milling Unit ..................................................... 50 16. Interim Crown Cemented with Tempgrip® Under a Four Pound Load ......... 51 17. 60 Cemented Interim Crowns and Dies .......................................................... 51 18. Thermocycler Used to Age the Interim Crowns ............................................. 52 19.Interim Crowns Placed in 0.5% Acid Fuchin for 24 Hours ............................. 52 DEH>+(&&!A*)'%(3!(,!A*)'%(3*:!>*+*)®Z!#*6%(®!>CM!S3'*+%=!>+(23!.'!D[! /.43%,%).'%(3 .................................................................................................. 54 21./.43%,%*:!W%*2!(,!'$*!O.)%.6!/.+4%3!(,!'$*!A*)'%(3*:!M%* HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH \\! !

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"! CHAPTER 1 INTRODUCTION The term CAD/CAM technology refers to computer aided design/computer aided

manufacturing. 1 It is equivalent to CAD/NC (Numerical Control) in some other industries. 2 Before it was developed, the manufacturing process in industries were controlled by hole punched paper which were fed into the controller machine that was wired to the machining tools. When CAD/NC technology became commercially available in the late 1960’s, it revolutionized the machining industry. The ability of doing work with minimal control and high precision raised manufacturing to a different level. 2 CAD/CAM was developed soon after and was also used by large companies in the aerospace and automotive world to help in graphic design. Some companies that first used this system included Boeing (Washington, United States), Renault (Boulogne, France) and General Motors (Michigan, United States). The advancement of this technology with the lowering of the cost of using CAD/CAM applications has resulted in its wider use. Today, CAD/CAM is seen in many engineering and electronic industries helping to design as well as to manufacture products. In the 1970s, Duret et al 3 were the first to venture into the use of CAD/CAM in dentistry. They built a digital scanner which was able to make an optical impression of an abutment which then used the data on a computer to design a contoured crown which was milled using a numerically controlled machine. They subsequently invented the commercially available Sopha system which some say might have been too advanced for its time. 3 Notable names like John Young and Bruce Altchuler in USA, Werner

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Mormann and Marco Brandestini in Switzerland also made initial advancements in CAD/CAM in the late 1970s.4 In the 1980’s, CAD/CAM revolutionalized the way dentistry was practiced. The initial CAD/CAM technology (Cerec® (Sirona®) Bensheim, Germany) allowed inlays to be delivered in a single visit reducing chair side and laboratory time. 5 However, this system could only fabricate inlays and was unable to produce correct occlusal contours with anatomical morphology.6 Because of the difficulties of making an optical impression intra-orally, the second generation of CAD/CAM required a conventional impression of the abutment followed by digitizing the data using an optical scanner of the stone model before milling the crown. 3 More sophisticated instruments were later developed and used to scan the cast like the contact probe and laser beam. 3 The second generation of CAD/CAM machines could fabricate both metal and ceramic restorations. 3 The third generation of CAD/CAM machines required scanning the casts in office and having networked processing for milling the crowns. 3 It is now possible using CAD/CAM technology, to digitally mill removable partial denture frameworks (Sensible® ) and maxillofacial prosthesis. CAD/CAM is a key to dental treatment of the future. 7 Currently, the use of CAD/CAM machines can mill zirconia frameworks in the laboratory. Frameworks can either be milled in its green stage or after being sintered. Both systems have problems as shrinkage happens after the zirconia material is sintered and sophisticated calculations have to be incorporated to take into consideration the amount of shrinkage during milling. If zirconia blocks are milled after sintering, high wear of the drill bits has been observed.3

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$! CAD/CAM technology also has advanced into fabricating complete dentures. 8

The technique requires the dentist to reform an old denture of a patient with the aid of a reline and a clinical remount. This is followed by a cone beam computed tomograph being made with the dentures in place intra-orally at maximum intercuspation. With this 3D information of the mucosal surface of the reformed denture, the computer designs the morphology of the denture together with the information of conventionally available denture teeth. The denture base is then milled and teeth bonded onto it before it is finished. These denture bases have the advantage of minimal shrinkage as the base does not have to be heat processed. 8 Other ways of interpreting these 3D data include rapid prototyping, stereolithography and 3D printing. With the use of CAD/CAM, it is possible to fabricate surgical guides which makes surgical implant placement more accurate. Companies like Simplant® (Materialise Dental,Leuven, Belgium) and Nobel biocare® (Zurich, Switzerland) have developed systems using cone beam computer tomography (CBCT) to fabricate surgical guides. This system eliminates the guess work in planning implant surgery. A surgical guide made this way is very precise and is capable of reducing the time required for presurgical planning. CAD/CAM milling procedures include converting the object into data with the help of a scanner, the data is then read and interpreted by a computer software and the software initiates a milling machine to create the final product. These products can be manufactured chairside, in the laboratory or in a distant centralized laboratory.3 The chairside production involves having a milling machine close to the clinic in order to reduce total treatment time. The conventional laboratory way of manufacturing

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involves making a PVS impression and sending the impression to a laboratory where a cast is poured in dental stone. The laboratory then uses the CAD/CAM instruments to manufacture the product by scanning the master cast. 3 A centralized production centre involves having satellite scanners in a laboratory which is connected to the milling units of the production scanner. This reduces the cost of production as the laboratory need not purchase the milling unit. 3 Any CAD/CAM system consist of 3 components. The scanner, the design software and the milling unit. 3 Two kinds of scanners currently exist, the optical scanner and the mechanical scanner. The optical scanner involves having a white light or laser light source reflected on the preparation which is captured by the computer. Examples of the optical scanner systems are: - Lava® scan ST (3M® ESPE) Minnesota, United States (Figure 1) - Everest® scan (Kavo®) Wiesbaden, Germany (Figure 2) - Es1 (Etkon®) Texas, United States (Figure 3)

Figure 1. Image of Lava® Scan ST (3M® ESPE) http://solutions.3m.com/wps/portal/3M/en_US/WW3/Country/

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Figure 2. Image of Everest® Scan Pro (Kavo®) http://www.kavo-cadcam.com/Everest-System/Everest-scan-pro.aspx

Figure 3. Image of Es1 (Etkon®) http://dlkdentallab.com/products/etkon.php

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'! The mechanical scanner involves having the master cast being scanned line by

line by a ruby ball which then sends the data to the computer. An example of this type of scanner would be: - Procera® (Nobel Biocare®) Zurich, Switzerland. (Figure 4)

Figure 4. Image of Procera® Forte (Nobel Biocare) http://www.nobelbiocare.com/en_us/splash/

Different manufacturers have developed different software systems which are designed for their own scanners and milling machines. The interfaces differ from each other which provide variations in handling the manufacturing process. The milling devices differ in the number of milling axis. They come with three, four and five milling axis. The three axis systems mill the products in X, Y and Z axis and are cheaper and easy to use. 9 Examples of three axis milling systems include:

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- Cerec® In Lab (Sirona®) Bensheim, Germany (Figure 5) - Lava® scan ST (3M® ESPE) Minnesota, United States (Figure 6) - Cercon® Brain (Degudent®) Hanau-Wolfgang, Germany (Figure 7) - E4D® (D4D Technologies) Texas, United States (Figure 8)

Figure 5. Cerec® In Lab (Sirona®) MC XL CAD/CAM Milling Machine http://www.cereconline.com/cerec/milling.html

The four axis milling systems allow adjustment of the tension bridge on top of the three axis of milling. Example of four axis milling system include: - Creative Dental Laboratory (Scottsdale, Arizona, United States) (Figure 9)

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Figure 6. Image of Lava® CNC 500 (3M® ESPE) Milling Machine Machinhttp://proto3000.com/3m-lava-cnc-500-milling-machine-overview.php

Figure 7. Image of Cercon® Brain (Degudent®) Milling Unit http://prosthetics.dentsply.com/

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Figure 8. Image E4D® (D4D Technologies) Milling Unit http://www.e4d.com/

Figure 9. Image of Digital Dental 4 – Axis (Creative Dental Laboratory) Milling Unit http://creativedentalaz.com

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"+! The five axis milling systems involve being able to adjust the tension bridge as

well as being able to rotate the milling spindle on top of the three dimensions of milling. This allows the system to mill FPDs as well as more complicated super structures. Examples of five axis milling systems include: - ARCTICA Engine ( Kavo®) Wiesbaden, Germany (Figure 10) - HSC milling device (Etkon®) Texas, United States (Figure 11)

Figure 10. Image of Kavo ARCTICA Engine !

http://www.kavo.com

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Figure 11. Image of HSC 20 Linear Milling Unit _____________________________________________________________________ http://www.dmgmoriseikiusa.com/hsc-series/hsc-20-linear

The Cerec® technology which was derived from the term “Computer Assisted Ceramic Reconstruction” 7 was created by Mörmann and Brandestini 7 at the University of Zurich in 1980 and was the first commercial CAD/CAM system in dentistry. It started with Mörmann developing an idea of wanting to create inlays fast while the patient was in the dental chair. He then discussed this with his friend Dr.Brandestini who was an electrical engineer. The optical components of the Cerec® optical scanner had to be first purchased from the makers of military equipment. The process of making an optical impression then was created which was done by the operator. Dr.Alain Ferru, a French software engineer was hired to create the Cerec® 1 operating system. To ease the process, the occlusal anatomy was created by having straight lines and it was up to the dentist to create the occlusal morphology. CAD/CAM technology then became more sophisticated with the introduction of Cerec® 1 which allowed production of single and dual surfaces inlays. 10 The Siemens CEREC® Team

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then evolved the software with Cerec® 2. The Cerec® 2 marketed in 1994 was equipped with an additional cylinder diamond which could mill inlay, onlays, crowns and veneers. Cerec® 3 which is a two bur system developed in 2000 was a windows based CAD-CAM system. 10 In 2006, the step bur was created to increase the precision and durability of the Cerec® 3. Cerec® has been gaining popularity as it allows dentists both within the USA and globally to deliver crowns in a single visit. With the revolution of implant dentistry, the Cerec® system can also be used to manufacture polymethyl metharcylate (PMMA) interim crowns (Telio®, Ivoclar vivadent, Liechtenstein, Germany ) Founded in 2003 by Mark and Henley Quadling, D4D technologies, Texas, United States was developed and produced in Dallas, Texas, USA. The company uses expert in-house teams of electrical, mechanical, optical, firmware and software engineers to design and develop the most innovative and patented technologies for healthcare performance. The duo got involved in CAD/CAM in 1998 and started a business which operated 3D scanners and software. This developed into another business related to 3D imaging in 2000 before starting up the D3D and then D4D technologies in 2003 with the help of other investors. In collaboration with Henry Schein (New York, United States), E4D® Dentist (D4D technologies, Richardson, Texas) was launched in 2008 and made commercially available to the dental industry. They were at most international dental meetings introducing their product. Today, E4D® Dentist is found not only in private dental clinics, but also in dental schools throughout the United States of America. D4D technologies have grown into other markets including military equipment and government installations in the United States as well as the region. 11 Although

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CAD/CAM technology has become more popular in clinical dentistry, 12 little research has been done towards investigating the accuracy of its use to make interim crowns. Purpose of Study This study investigated the accuracy of interim crowns fabricated using CAD/CAM technology compared to interim crowns fabricated from polymethyl methacrylate (PMMA) materials such as Jet® and Caulk® resin. The cemented crowns were evaluated by measuring marginal discrepancies and dye penetration. Research Hypothesis Null hypothesis #1: There is no statistical significant difference in the vertical and/or horizontal component of the marginal fit of the polymethyl metharylate or resin based composite interim crowns manufactured by CAD/CAM when compared to crowns made conventionally with PMMA such as Caulk® and Jet® resins. Alternative hypothesis #1: There is a statistical significant difference in the vertical and/or horizontal component of the marginal fit of the polymethyl metharylate or resin based composite interim crowns manufactured by CAD/CAM when compared to crowns made conventionally with PMMA such as Caulk® and Jet® resins. Null hypothesis #2: There is no statistically significant relationship between the size of the vertical and/or horizontal component of the marginal gap and the penetration of dye after thermocycling. Alternative hypothesis #2: There is a statistically significant relationship between the size of the vertical and/or horizontal component of the marginal gap and the penetration of dye after thermocycling

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"%! CHAPTER 2 REVIEW OF LITERATURE Evaluation of the Accuracy of CAD/CAM Systems Although CAD/CAM systems have been on the market since the invention of the

Cerec® (Bensheim, Germany) system 27 years ago, only a moderate amount of research had been reported on their accuracy and the survival rates of inlays and crowns produced with this technology. The following studies discuss the accuracy of the products and their clinical survival rates. A 10 year retrospective clinical study was conducted by Zimmer at al13 in a private practice in Germany. They examined the restorations and marked them as failure if they had secondary caries, any kind of loss of the restoration, fracture of the restoration, tooth fracture or marginal gap reaching dentin or base material. Out of 308 restorations that were initially identified, they examined a total of 226 Cerec®1 all ceramic restorations which included 39 class I inlays, 84 class II inlays and 103 with 3 or more surfaces inlay restorations after ten years. They reported that they had a five years survival rate of 94.7% and a ten years survival rate of 85.7%. The remaining 82 restorations that were not accounted for belonged to patients who had either relocated (15), died (two) or had other personal problems (four) so that they could not return for follow up. They were not included in the statistical analysis. The restorations in this study were mainly class I, class II and one and two cusps restorations. Cerec®1 was not able to fabricate crowns when this study began. A systemic review by Wittneben et al14 reported that the success rate of CAD/CAM crowns over 5 years was 91.6%. The team did an online search for related

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articles and discovered a total of 14 prospective articles and two retrospective articles. A total of 1,957 CAD/CAM crowns were evaluated and 98% of them were on posterior teeth. These crowns had an average exposure time of 7.9 years intra-orally. The team found that a total of 170 crowns had failed. The review was only on Cerec®1, Cerec® 2 and Celay® crowns. This study may not be a good representation of the success rates of CAD/CAM crowns because other systems are now available. An evaluation of the results found that the authors did not differentiate between anterior teeth and posterior teeth. The actual success rate for anterior teeth might be higher. No randomized clinical trials are available that have evaluated the success of CAD/CAM crowns. Internal Adaptation of Crowns and Marginal Discrepancies The intaglio surface of a crown is critical for the retention and resistance form of the crown. 15 Having a better adapted crown will increase the success and longevity of the crown. 16 An irregular integlio surface might also prevent the crown from completely seating and so resulting in an open margin.

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A study carried out by Nakamura and Dei18

evaluated the marginal and internal fit of Cerec® 3 crowns. They examined 3 different angles of convergence, four, eight and 12 degrees and three different luting spaces ten, 30 and 50 micrometers. A total of 45 crowns were fabricated with nine different variations. They assessed the marginal discrepancies by measuring the marginal gap and the thickness with Fit checker (GC America, Illinois, United States) between the die and the !

crown to determine the internal gap. The marginal gap was measured from the outer most part of the crown margin to the shoulder margin of the tooth. The surface area of the abutment was determined by using a non contact contour measuring device. The internal gap was then calculated with the basis of surface area of the abutment, the weight

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and density of the fit checker within the crown. They found that the marginal discrepancy was not affected by the occlusal convergence angle when the luting space was 30 to 50 microns. They also reported that the marginal discrepancy was between 53 to 108 microns which was below the clinically acceptable range advocated by Mclean and von Fraunhofer19 of 120 microns. This study however did not fatigue test the crowns and hence may not be an accurate gauge of the marginal discrepancy of the crowns over time. Another study20 investigated the marginal and internal fit of all ceramic crowns fabricated with Procera® (Nobel Biocare, Zurich, Switzerland) and Cerec 3D on Dentoform (Columbia Dentoform, New York, United States) teeth. A mandibular 2nd !

premolar was prepared with a 1.00 mm margin. An impression was made with PVS and a resin model of the tooth was made to fabricate ten dies in metal. These ten dies were used to fabricate Procera® (Nobel Biocare, Zurich, Switzerland) copings and Cerec® crowns. Porcelain was subsequently added to the Procera® copings. These copings and crowns were evaluated on the metal dies for marginal discrepancy. Using a silicone paste to mimic cement and a load of 20Ncm pressure to mimic finger pressure, the internal gap was evaluated by measuring the thickness of the silicone remaining inside the crown with the silicone’s overall weight and density. Thickness = weight / (surface area ! density) They found that there was no statistically significant difference in the internal gap between the double layered Procera® crown and Cerec® crown. The marginal discrepancies of Procera® crowns were statistically larger after porcelain placement. There was a statistically significant difference between the internal gap of the Procera®

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and Cerec® systems. The Procera® system had a smaller internal gap. Both CAD/CAM crowns were found to have satisfactory results within the clinical acceptable limit of 123 to 154 micron range of marginal discrepancy. The authors in this article discussed the existence of the larger marginal discrepancy which they explained could have been due to the bigger bur size which was used to mill the specimens. This could be a limiting factor of CAD/CAM technology until more accurate milling devices are developed. A study by Beuer et al21 evaluated the marginal and internal fit of frameworks milled from semi-sintered zirconia blocks that were designed and machined with two CAD/CAM systems namely the Etkon (Texas, United States) and Cerec® In Lab and one !

CAM system Cercon® (Hanau-Wolfgang, Germany). Ten frameworks were made, cemented, embedded and sectioned. The margins and internal fit were measured using a microscope with 50x magnification and an evaluation of the results showed a marginal gap size of 21µm for premolars using the Etkon®, for Cerec inLab® it was 46.7 µm and for Cercon® it was 82.4 µm. For molars the marginal gap sizes were bigger for all groups. The Etkon® system produced the best marginal fit. The limitations of this study was that the laboratory technician was the one in charge of evaluating the retainers in the study, the retainers were placed on definitive dies hence the clinical and laboratory errors were excluded and only one cementation technique was tested. Another study by Reich22 evaluated the marginal and internal fit of three different all-ceramic 4-unit CAD/CAM units which fabricated fixed partial dentures (FPD) in comparison to metal-ceramic FPDs made for a previous study. The Cerec®, Lava® (3M® ESPE, Minnesota, United States) and Digident® (Girrbach Dental GmbH, Pforzheim, Germany) systems were used to make eight samples each of the three unit FPD

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frameworks. The samples were examined using a replica technique. In the replica technique, the samples had light body silicone injected into the retainers of the FPD and then were loaded with a 20N pressure. The excess silicone was removed when the silicone was set. The FPD was removed from the abutments and the light body silicone was reinforced with heavy body silicone. These replicas were then sectioned three times in the mesio distal direction and once in the bucco lingual direction. The samples were examined under a microscope and the median marginal gaps were: 75 µm for Digient®, 65 µm for LAVA® and for Cerec® it was 54 µm for conventional FPD. The internal fit of all the ceramic FPD’s were not as accurate as conventional FPD. The results of this experiment however had to be interpreted with caution as only 8 samples of each material were used. The vertical marginal discrepancies of CAD/CAM, WAX/CAM, and WAX/CAST restorations were evaluated in an in vitro study by Cvar. 23 The WAX/CAM copings were waxed copings that were subsequently scanned and milled by the CAD/CAM machine. The WAX/CAST copings were the copings that were waxed up and cast. The study involved seating ten restorations of each group on a master die. High-resolution digital photographs of the marginal area on all four sides were made. The vertical marginal opening was then measured using a calibrated digital software program. The vertical margin discrepancies for CAD/CAM were 79.43 ± 25.46 µm and for WAX/CAM were 73.12 ± 24.15 µm and for WAX/CAST were 23.91 ± 9.80 µm. There was a statistically significant difference between the WAX/CAST group and the other two groups. There was no difference between the vertical marginal discrepancies of the CAD/CAM and WAX/CAM. The copings made from the WAX/CAST technique

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had smaller vertical marginal discrepancies when compared to either CAD/CAM or WAX/CAM. However, this study only measured the vertical and not the horizontal discrepancies. This study used a cement space of 80 microns instead of a smaller amount. It also could have used other forms of CAD/CAM copings which might have had better results instead of the titanium copings that were used. Types of Margins In determining the margin that is best for a preparation, a study by Byrne24 had three different identical preparations made with three different finish line designs. A chamfer margin, a shoulder margin and a shoulder bevel margin. Fifteen epoxy resin dies were fabricated for each finish line design. Thirty cast crowns were fabricated on their respective epoxy resin dies by making an impression of them in additional polymerization silicone and pouring the dies for casting in type IV resin impregnated gypsum stone. Fifteen of them were cemented with zinc phosphate while another fifteen were left uncemented on the resin dies. Another fifteen cast crowns were fabricated and fitted onto its stone die as a control. The specimens were embedded in clear epoxy and sectioned at the midline to determine the adaptability of the margins. The results showed that the finish line did not affect the fit of the cemented crowns. A beveled margin was not significantly superior in marginal fit upon cementation. These results were however from in in-vitro study and may not be the same when used clinically. Syu et al25 in the following year tested castings on three different margins, a shoulder, shoulder bevel and chamfer without cementing them on their respective dies. Ten castings were made for each type of finish line. The crown together with their dies were sectioned and examined. No statistically significant differences were noted with the

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marginal and axial gaps between the three finish lines. The authors made the assumption that the cementation process would not change the seating process of the crowns by increasing the marginal gap. A study by Akbar26 investigated 16 Paradigm® MZ100 crowns made from Cerec® 3. Eight crowns were fabricated with a 1.0mm Chamfer finishline while the other eight crowns were fabricated with a 1.2-1.5mm shoulder finish line. The crowns were evaluated using the United States Public Health Service (USPHS) criteria at eight predetermined sites. The marginal gaps at four axial walls were also evaluated using a scanning electron microscope. Fifteen measurements were taken at each axial wall. A total of 60 measurements were made for each crown. In this study, 100 microns was the maximum gap permitted to classify a crown as clinically acceptable. With crown acceptability being based on the eight sites needing to be below 100 microns, four out of the eight crowns with chamfer margins and three out of the eight crowns with shoulder margins had margins less than 100 microns. There was no statistically significant difference between the two different margins. Using the mean marginal discrepancy, crowns made with both the chamfer and the shoulder margins were found to be acceptable. In this study, the optical scanner was used outside the mouth away from the interference of the saliva contamination. Results might not be as accurate when the optical scanner is used intra-orally in the presence of saliva. Bindl and Mormann27 reported that of the mean marginal gap of Cerec® 1 intracoronal crowns were 63 – 228 microns while the mean marginal gap of Cerec® 2 intracoronal crowns were 56 and 121 microns. 27 These data was based on 818 Cerec® partial crowns that were placed in 496 patients. The crowns were divided into 3 groups

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differentiated by the milling softwares of Cerec® 1, Cerec® 2 with standard wall software and Cerec® 2 with wall spacing software. From these partial crowns, an average of 12 partial crowns were randomly selected from each group and using the replica technique, the samples were analyzed for marginal adaptation under a scanning electron microscope by two calibrated observers. This data were based on a total of 12 crowns which although randomly selected represented only a fraction of 818 partial crowns that were ultimately cemented. The replica technique though reliable might not be the best method for analyzing the marginal adaptation.28 Methods for Evaluation of Marginal Discrepancy The methods of evaluating marginal discrepancies of a crown can affect the accuracy of the findings. A study 29 done at The University of Iowa utilized dental students and prosthodontists to examine the marginal gap of a crown. Three extracted teeth were fitted onto a Dentoform® mounted on a supine mannequin. Crown preparations and final impressions were made of the three teeth. Crowns were made with different marginal gaps and the dental students and prosthodontists had to rate the margins using an explorer. The rating system was either clinically acceptable or unacceptable. The participants rated the crowns twice with an interval of six months between examinations. The results of the test found that crowns with greater marginal discrepancies were rated clinical unacceptable more often. This study was done in vitro and in the presence of adequate lighting and in a dry field. The results might be different if this was done intra-orally with limited light source especially for posterior teeth. The United States Public Health Service (USPHS) criteria method investigates a tooth by means of visual as well as tactile inspection using an explorer. 30 The paper

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published in 1971 explained how inter-examiner calibration can be developed as well as how a tooth or a preparation can be visually acceptable under the criteria suggested by USPHS. Digital Impressions Digital impressions are being used more often and in the near future may take over from conventional impressions made with polyvinyl siloxane material. 31 Subgingival margins will remain a challenge for clinicians using both types of impression techniques. 32 Although digital impressions will require even more isolation prior to making the impression, advantages of digital impressions include the elimination of custom trays, the elimination of the problem of impression material separating from the tray and distortion of the impression material prior to pouring. 33 Another advantage is that digital information from digital impressions can be stored and reproduced at a later time. Digital impressions may save both money and time for the clinician and become more accurate as the technology develops.31 A study by Syrek34 comparing all ceramic zirconia crowns made from a CAD/CAM (LAVA® C.O.S) impression and the two step silicone impression material found that the crowns made from the CAD/CAM impression had a better marginal fit. Fourteen molars and four premolar crowns were prepared for 18 patients. Each patient only had one crown. Both a digital impression and a two-step silicone impression were made for each tooth. All ceramic zirconia crowns were fabricated from the impressions and the crowns were seated on the tooth at the fitting appointment. Silicone material was used to mimic cement and this silicone was removed and only the marginal gap was measured. The crowns made with digital impressions had a median marginal gap of 49

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microns when compared to the median gap of 71 microns for the crowns made with the two-step silicone impression material. 34 A Mann-Whitney test was performed between the groups and a statistically significant difference was found between the groups (p
I33S

"K++VC/1:/70!6H1//2/40! Questions to Evaluate the Hypothesis in this Study

1. Is there a difference in the marginal fit of the PMMA and resin based composite crowns made by the Cerec® and E4D® systems respectively as compared to those made conventionally from PMMA? 2. If there is a difference, is it on the buccal or the lingual and in what direction? 3. Is there a difference in the dye penetration between the various crowns after thermocycling? 4. Is there a relationship between the gap sizes of the margins and the dye penetration between the various crowns?

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Table 1 – Table of Materials Interim Crowns

Manufacturer/ Country

Telio CAD !

Ivoclar vivadent, 6277722AN/ N08070 Liechtenstein, Germany)

Paradigm MZ100

3M ESPE, Minnesota, United States

Caulk Temporary Bridge Resin

Dentsply/ Caulk Pennsylvania, United States

Jet

Lang Dental, Illinois, United States

!

!

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Reference / Lot Numbers

!

70-20105339-7/ N342150

Material

Fabrication Method

PMMA (99.5%) Pigments less than 1.0%

CAD/CAM

Matrix: Bis-GMA, TEGDMA Filler: 85wt % Zirconia-Silica

CAD/CAM

PMMA + MMA

Conventional Direct Method

PMMA + MMA

Conventional Direct Method

WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW! PMMA= polymethyl metharcylate Bis-GMA= bisphenol A diglycidyl ether dimethacrylate TEGDMA tri-ethylene glycol dimethacrylate MMA= methyl methacrylate

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Figure 14. Cerec® 3 System with the Cerec® Milling Unit ______________________________________________________________________ Source: http://www.cereconline.com/cerec/

Figure 15. E4D® System with the E4D® Milling Unit ______________________________________________________________________ Source: http://www.e4d.com

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Figure 16. Interim Crown Cemented with Tempgrip® Under a Four Pound Load.

Figure 17. 60 Cemented Interim Crowns and Dies

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!

Figure 18. Thermocycler Used to Age the Interim Crowns

Figure 19. Interim Crowns Placed in 0.5% Acid Fuchin for 24 Hours.

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&$! CHAPTER 4 RESULTS Of the 60 samples examined, one sample from the Paradigm® MZ100 group

dislodged during the thermocyling process and was removed from the study. The data for the remaining 59 interim crowns were used to answer the research questions. Assessment of Reliability of the Marginal Discrepancy Measurements Re-measurements were made on 16 randomly selected interim crowns (four from each group). The results of the intra-class correlation showed that there was a very strong evidence that intra-class correlation differed from zero (p=0.0005), and the correlation coefficients of 0.86 indicated a strong agreement between the two measurements made by the same observer. Moreover, no significant difference existed between the two measurements made by the same observer (mean difference between the two measurements: 0.01(±0.04); p=0.3117 (a paired-sample t-test). Histological Evaluation of Samples X3H81/!#+! !

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,/G3-®!Q?Z!340/132!71-;4!6:0/1!L/34H! !

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7-2C80/1!L9!05/!P26H/!b1-® Plus software version 5.1. !?G
surface of the crowns was also evaluated. An evaluation of the results of the one-way ANOVA revealed that there was a statistically significant difference between the crowns for the mean horizontal component of the marginal discrepancy at the lingual surface (F(3,55)=6.58; p=0.0007) . The post-hoc Tukey-Kramer test indicated that the mean horizontal component of marginal discrepancies at the lingual surface for Caulk and Jet !

were significantly greater than those observed for Telio® CAD and Paradigm® MZ100. There was no statistically significant difference found between Caulk and Jet or !

!

between Telio® and Paradigm® MZ100 as shown in Table 7.

Table 7 – Mean Horizontal Component of Marginal Discrepancy at the Lingual Surface for the Different Types of Crowns

Types of Crown

N

Mean Horizontal Component of Marginal Discrepancy at the Lingual Surface / (SD) in mm

Caulk®

15

0.16 (0.18)

A

Jet®

14

0.13 (0.09)

A

Cerec®/ Telio® CAD

15

0.03 (0.05)

B

E4D®/ Paradigm® MZ100

15

0.02 (0.03)

B

Group Comparisons**

**Means with the same letter are not significantly different using the post-hoc TukeyKramer test (P>.05).

!

!

'#! To determine if there was a difference between the mean vertical component of

the facial and lingual marginal discrepancies among four types of crowns, a one-way ANOVA was used and it showed that there was a statistically significant difference between the mean vertical components of the facial and lingual marginal discrepancies (F(3,55)=3.76; p=0.0158). An evaluation of the post-hoc Tukey-Kramer test indicated that the mean difference between vertical component of the facial and lingual surfaces for the Caulk® crowns were statistically significantly larger than those observed for the Jet® and E4D® / Paradigm® MZ100 interim crowns. However, there was no significant differences found between the Caulk interim crowns and Cerec® / Telio® CAD resin !

interim crowns and among Cerec® / Telio® CAD, E4D® / Paradigm® MZ100 and Jet interim crowns as shown in Table 8.

Table 8 - Difference Between the Mean Vertical Component of the Marginal Discrepancies at the Facial and Lingual Surfaces for the Different Types of Crowns Mean Difference Between the Vertical Component of the Group Facial and Lingual Marginal Comparisons** Discrepancies / (SD) in mm

Types of Crowns

N

Caulk®

15

0.17 (0.12)

Cerec® / Telio®CAD

15

0.10 (0.08)

Jet®

15

0.08 (0.07)

B

E4D® / Paradigm® MZ100

14

0.07 (0.06)

B

A A

B

**Means with the same letter are not significantly different using the post-hoc TukeyKramer test (P>.05).

!

'$! To assess if there was a difference between the mean horizontal component of the

facial and lingual marginal discrepancies, a one-way ANOVA revealed that there was no statistically significant difference between these crowns. (F(3,55)=0.87; p.05).

!

'%! To determine if there was a difference between the mean vertical component of

marginal discrepancies at the facial and lingual surfaces within each type of crown, a paired t-test was used. There was a statistically significant difference found between the vertical component of the marginal discrepancies between the facial and lingual surfaces for Cerec®/ Telio® CAD interim crowns (p=0.0005). An evaluation of the data showed that vertical component of the marginal discrepancies at the facial surface were significantly larger than that of the lingual surface for the Cerec®/ Telio® CAD (0.18mm vs. 0.09mm) crowns. Also, there was also a significant difference for the mean vertical component of the marginal discrepancies at the facial and lingual surfaces for E4D®/ Paradigm® MZ100 interim crowns (p=0.0003). An evaluation the data showed that the vertical component of the marginal discrepancies at the facial surface were significantly greater than that at the lingual surface for E4D®/ Paradigm® MZ100 interim crowns (0.13mm vs. 0.09mm). There also was a significant difference for the mean vertical component of the marginal discrepancies at the facial and lingual surfaces for Caulk® interim crowns (p=0.0001). An evaluation of the data showed that the vertical component of the marginal discrepancies at the facial surface were significantly larger than that of the lingual surface for Caulk® interim crowns (0.29mm vs. 0.13mm). A similar relationship was found for the Jet® interim crowns as there was a significant difference for the mean vertical component of the marginal discrepancies (p=0.0006). An evaluation of the data showed that the vertical component of the marginal discrepancies for the facial surface were significantly larger than that of the lingual surface for the Jet® interim crowns (0.15mm vs. 0.11mm).

!

'&! To evaluate if there were any differences between mean horizontal component of

the marginal discrepancies at the facial and lingual surfaces for each type of crowns, a paired –sample t-test was used. There was a significant difference between the horizontal component of the marginal discrepancies for Cerec®/ Telio® CAD crowns (p0.05), except for two groups of interim crowns. There was a significant relationship between the percentage of dye penetration and the horizontal component of the facial marginal discrepancy for Jet® interim crowns. Pearson correlation coefficient of 0.74 indicated a moderate positive relationship between the two variables. In addition, there was also a significant relationship between percentage of dye penetration and the marginal discrepancy on the lingual surface for Caulk® resin interim crowns. The Pearson correlation coefficient of 0.67 indicated a moderate positive relationship between the two variables.

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Table 12 - Correlation Between Dye Penetration and Horizontal Component of the Marginal Discrepancies at the Facial and Lingual Surfaces

Types of Crowns

Horizontal Component of Facial Marginal Discrepancy

Horizontal Component of Lingual Marginal Discrepancy

Correlation* Coefficient

P – Value

Correlation* Coefficient

P – Value

Cerec® / Telio® CAD

- 0.24

0.39

-0.01

0.96

E4D®/ Paradigm® MZ100

- 0.18

0.54

0.04

0.89

Caulk®

0.07

0.80

0.67


!

!

)#! REFERENCES

1. Beuer, F.; Schweiger, J.; Edelhoff, D. Digital dentistry: an overview of recent developments for CAD/CAM generated restorations. Br. Dent. J. 2008, 204, 505511. 2. Harvard University Graduate School of Design http://internal.gsd.harvard.edu/inside/cadcam/whatis.html. 3. Miyazaki, T.; Hotta, Y. CAD/CAM systems available for the fabrication of crown and bridge restorations. Aust. Dent. J. 2011, 56 Suppl 1, 97-106. 4. Young, J. M.; Altschuler, B. R. Laser holography in dentistry. J. Prosthet. Dent. 1977, 38, 216-225. 5. Mormann, W. H. The origin of the Cerec method: a personal review of the first 5 years. Int. J. Comput. Dent. 2004, 7, 11-24. 6. Mormann, W. H.; Brandestini, M.; Lutz, F.; Barbakow, F. Chairside computer-aided direct ceramic inlays. Quintessence Int. 1989, 20, 329-339. 7. Mormann, W. H. The evolution of the CEREC system. J. Am. Dent. Assoc. 2006, 137 Suppl, 7S-13S. 8. Kanazawa, M.; Inokoshi, M.; Minakuchi, S.; Ohbayashi, N. Trial of a CAD/CAM system for fabricating complete dentures. Dent. Mater. J. 2011, 30, 93-96. 9. Mehl, A.; Gloger, W.; Kunzelmann, K. H.; Hickel, R. A new optical 3-D device for the detection of wear. J. Dent. Res. 1997, 76, 1799-1807. 10. Poticny, D. J.; Klim, J. CAD/CAM in-office technology: innovations after 25 years for predictable, esthetic outcomes. J. Am. Dent. Assoc. 2010, 141 Suppl 2, 5S-9S. 11. D4D Technologies http://www.e4d4u.com/474306/2012/06/15/history-of-d4dtechnologies.html. 12. Galhano, G. A.; Pellizzer, E. P.; Mazaro, J. V. Optical impression systems for CADCAM restorations. J. Craniofac. Surg. 2012, 23, e575-9. 13. Zimmer, S.; Gohlich, O.; Ruttermann, S.; Lang, H.; Raab, W. H.; Barthel, C. R. Long-term survival of Cerec restorations: a 10-year study. Oper. Dent. 2008, 33, 484-487. 14. Wittneben, J. G.; Wright, R. F.; Weber, H. P.; Gallucci, G. O. A systematic review of the clinical performance of CAD/CAM single-tooth restorations. Int. J. Prosthodont. 2009, 22, 466-471.

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15. Rosenstiel, L.,Fujimoto In Principles of Tooth preperation; Contemporary Fixed Prosthodontics; Elsevier: 2008; pp 238-239. 16. Yuksel, E.; Zaimoglu, A. Influence of marginal fit and cement types on microleakage of all-ceramic crown systems. Braz Oral Res. 2011, 25, 261-266. 17. Cruz, M. A.; Sorenson, J. A.; Johnson, W. K. Effect of venting and seating techniques on the cementation of complete coverage restorations. Oper. Dent. 2008, 33, 690695. 18. Nakamura, T.; Dei, N.; Kojima, T.; Wakabayashi, K. Marginal and internal fit of Cerec 3 CAD/CAM all-ceramic crowns. Int. J. Prosthodont. 2003, 16, 244-248. 19. McLean, J. W.; von Fraunhofer, J. A. The estimation of cement film thickness by an in vivo technique. Br. Dent. J. 1971, 131, 107-111. 20. Lee, K. B.; Park, C. W.; Kim, K. H.; Kwon, T. Y. Marginal and internal fit of allceramic crowns fabricated with two different CAD/CAM systems. Dent. Mater. J. 2008, 27, 422-426. 21. Beuer, F.; Aggstaller, H.; Edelhoff, D.; Gernet, W.; Sorensen, J. Marginal and internal fits of fixed dental prostheses zirconia retainers. Dent. Mater. 2009, 25, 94102. 22. Reich, S.; Kappe, K.; Teschner, H.; Schmitt, J. Clinical fit of four-unit zirconia posterior fixed dental prostheses. Eur. J. Oral Sci. 2008, 116, 579-584. 23. Tan, P. L.; Gratton, D. G.; Diaz-Arnold, A. M.; Holmes, D. C. An in vitro comparison of vertical marginal gaps of CAD/CAM titanium and conventional cast restorations. J. Prosthodont. 2008, 17, 378-383. 24. Byrne, G. Influence of finish-line form on crown cementation. Int. J. Prosthodont. 1992, 5, 137-144. 25. Syu, J. Z.; Byrne, G.; Laub, L. W.; Land, M. F. Influence of finish-line geometry on the fit of crowns. Int. J. Prosthodont. 1993, 6, 25-30. 26. Akbar, J. H.; Petrie, C. S.; Walker, M. P.; Williams, K.; Eick, J. D. Marginal adaptation of Cerec 3 CAD/CAM composite crowns using two different finish line preparation designs. J. Prosthodont. 2006, 15, 155-163. 27. Bindl, A.; Mormann, W. H. Clinical and SEM evaluation of all-ceramic chair-side CAD/CAM-generated partial crowns. Eur. J. Oral Sci. 2003, 111, 163-169.

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28. Wolfart, S.; Wegner, S. M.; Al-Halabi, A.; Kern, M. Clinical evaluation of marginal fit of a new experimental all-ceramic system before and after cementation. Int. J. Prosthodont. 2003, 16, 587-592. 29. Bronson, M. R.; Lindquist, T. J.; Dawson, D. V. Clinical acceptability of crown margins versus marginal gaps as determined by pre-doctoral students and prosthodontists. J. Prosthodont. 2005, 14, 226-232. 30. Cvar, J. F. R.,G. Criteria For The Clinical Evaluation of Dental Restorative Materials. San Francisco Government Printing Office 1971. 31. Kurbad, A. Impression-free production techniques. Int. J. Comput. Dent. 2011, 14, 59-66. 32. Christensen, G. J. Will digital impressions eliminate the current problems with conventional impressions? J. Am. Dent. Assoc. 2008, 139, 761-763. 33. Cho, G. C.; Chee, W. W. Distortion of disposable plastic stock trays when used with putty vinyl polysiloxane impression materials. J. Prosthet. Dent. 2004, 92, 354-358. 34. Syrek, A.; Reich, G.; Ranftl, D.; Klein, C.; Cerny, B.; Brodesser, J. Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling. J. Dent. 2010, 38, 553-559. 35. Gegauff, A. G. H.,J. In Interim Fixed Restorations; Rosensteil, S., Land, M. and Fujimoto, J., Eds.; Contemporary Fixed Prosthodontics; pp 466-478. 36. Federick, D. R. The provisional fixed partial denture. J. Prosthet. Dent. 1975, 34, 520526. 37. Krug, R. S. Temporary resin crowns and bridges. Dent. Clin. North Am. 1975, 19, 313-320. 38. Poyser, N.; Porter, R.; Briggs, P.; Kelleher, M. Demolition experts: management of the parafunctional patient: 2. Restorative management strategies. Dent. Update 2007, 34, 262-4, 266-8. 39. Hernandez, E. P.; Oshida, Y.; Platt, J. A.; Andres, C. J.; Barco, M. T.; Brown, D. T. Mechanical properties of four methylmethacrylate-based resins for provisional fixed restorations. Biomed. Mater. Eng. 2004, 14, 107-122. 40. Amet, E. M.; Phinney, T. L. Fixed provisional restorations for extended prosthodontic treatment. J. Oral Implantol. 1995, 21, 201-206.

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41. Hochwald, D. A. Surgical template impression during stage I surgery for fabrication of a provisional restoration to be placed at stage II surgery. J. Prosthet. Dent. 1991, 66, 796-798. 42. Krennmair, G.; Krainhofner, M.; Weinlander, M.; Piehslinger, E. Provisional implants for immediate restoration of partially edentulous jaws: a clinical study. Int. J. Oral Maxillofac. Implants 2008, 23, 717-725. 43. Ehrenberg, D.; Weiner, G. I.; Weiner, S. Long-term effects of storage and thermal cycling on the marginal adaptation of provisional resin crowns: a pilot study. J. Prosthet. Dent. 2006, 95, 230-236. 44. Alt, V.; Hannig, M.; Wostmann, B.; Balkenhol, M. Fracture strength of temporary fixed partial dentures: CAD/CAM versus directly fabricated restorations. Dent. Mater. 2011, 27, 339-347. 45. Kaiser, D. A. Accurate arcylic resin temporary restorations. J. Prosthet. Dent. 1978, 39, 158-161. 46. Tsitrou, E. A.; Northeast, S. E.; van Noort, R. Evaluation of the marginal fit of three margin designs of resin composite crowns using CAD/CAM. J. Dent. 2007, 35, 6873. 47. Akbar, J. H.; Petrie, C. S.; Walker, M. P.; Williams, K.; Eick, J. D. Marginal adaptation of Cerec 3 CAD/CAM composite crowns using two different finish line preparation designs. J. Prosthodont. 2006, 15, 155-163. 48. Gougaloff, R.; Stalley, F. C. Immediate placement and provisionalization of a dental implant utilizing the CEREC 3 CAD/CAM Protocol: a clinical case report. J. Calif. Dent. Assoc. 2010, 38, 170-3, 176-7. 49. Vahidi, F. The provisional restoration. Dent. Clin. North Am. 1987, 31, 363-381. 50. Rohmhass History of Plexiglas. http://www.rohmhaas.com/history/ourstory/innovation_plexiglastriumphs.htm. 51. Rueggeberg, F. A. From vulcanite to vinyl, a history of resins in restorative dentistry. J. Prosthet. Dent. 2002, 87, 364-379. 52. Devlin, H. Acrylic monomer--friend or foe? Quintessence Dent. Technol. 1984, 8, 511-512. 53. Burns, D. R.; Beck, D. A.; Nelson, S. K.; Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics A review of selected dental literature on contemporary provisional fixed prosthodontic treatment: report of the

!

)'! Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics. J. Prosthet. Dent. 2003, 90, 474-497.

54. Gratton, D. G.; Aquilino, S. A. Interim restorations. Dent. Clin. North Am. 2004, 48, vii, 487-97. 55. Perry, R. D.; Magnuson, B. Provisional materials: key components of interim fixed restorations. Compend. Contin. Educ. Dent. 2012, 33, 59-60, 62. 56. Ivoclar Vivadent Telio Instruction Manual. 2010. 57. 3M ESPE Paradigm MZ100 technical product profile. http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UF6EVsSyXTtOxM _5xF6EVtQEVs6EVs6EVs6E666666--2000). 58. Schmid-Schwap, M.; Graf, A.; Preinerstorfer, A.; Watts, D. C.; Piehslinger, E.; Schedle, A. Microleakage after thermocycling of cemented crowns--a meta-analysis. Dent. Mater. 2011, 27, 855-869. 59. Yoshida, K.; Sawase, T.; Watanabe, I.; Atsuta, M. Shear bond strengths of four resin cements to cobalt-chromium alloy. Am. J. Dent. 1995, 8, 285-288. 60. Diaz-Arnold, A. M.; Mertz, J. M.; Aquilino, S. A.; Ryther, J. S.; Keller, J. C. A comparison of the tensile strength of four prosthodontic adhesives. J. Prosthodont. 1993, 2, 215-219. 61. Gale, M. S.; Darvell, B. W. Thermal cycling procedures for laboratory testing of dental restorations. J. Dent. 1999, 27, 89-99. 62. Harashima, I.; Uzawa, T.; Hirasawa, T. A new method for assessment of marginal sealability of dental restorations. Dent. Mater. J. 1992, 11, 150-156. 63. Kim, J. Y.; Takahashi, Y.; Kito, M.; Morimoto, Y.; Hasegawa, J. Semi-quantitative analysis of early microleakage around amalgam restorations by fluorescent spectrum method: a laboratory study. Dent. Mater. J. 1992, 11, 45-58. 64. Momoi, Y.; Iwase, H.; Nakano, Y.; Kohno, A.; Asanuma, A.; Yanagisawa, K. Gradual increases in marginal leakage of resin composite restorations with thermal stress. J. Dent. Res. 1990, 69, 1659-1663. 65. Chan, M. F.; Jones, J. C. A comparison of four in vitro marginal leakage tests applied to root surface restorations. J. Dent. 1992, 20, 287-293. 66. Arcoria, C. J.; Fisher, M. A.; Wagner, M. J. Microleakage in alloy-glass ionomer lined amalgam restorations after thermocycling. J. Oral Rehabil. 1991, 18, 9-14.

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)(!

67. Crim, G. A.; Garcia-Godoy, F. Microleakage: the effect of storage and cycling duration. J. Prosthet. Dent. 1987, 57, 574-576. 68. Prati, C.; Tao, L.; Simpson, M.; Pashley, D. H. Permeability and microleakage of Class II resin composite restorations. J. Dent. 1994, 22, 49-56. 69. Kidd, E. A.; Harrington, E.; Grieve, A. R. The cavity sealing ability of composite restorations subjected to thermal stress. J. Oral Rehabil. 1978, 5, 279-286. 70. Palmer, D. S.; Barco, M. T.; Billy, E. J. Temperature extremes produced orally by hot and cold liquids. J. Prosthet. Dent. 1992, 67, 325-327. 71. Spierings, T. A.; Peters, M. C.; Bosman, F.; Plasschaert, A. J. Verification of theoretical modeling of heat transmission in teeth by in vivo experiments. J. Dent. Res. 1987, 66, 1336-1339. 72. Peterson, E. A.,2nd; Phillips, R. W.; Swartz, M. L. A comparison of the physical properties of four restorative resins. J. Am. Dent. Assoc. 1966, 73, 1324-1336. 73. Plant, C. G.; Jones, D. W.; Darvell, B. W. The heat evolved and temperatures attained during setting of restorative materials. Br. Dent. J. 1974, 137, 233-238. 74. Brown, W. S.; Jacobs, H. R.; Thompson, R. E. Thermal fatigue in teeth. J. Dent. Res. 1972, 51, 461-467. 75. Lloyd, B. A.; McGinley, M. B.; Brown, W. S. Thermal stress in teeth. J. Dent. Res. 1978, 57, 571-582. 76. Blum, J.; Weiner, S.; Berendsen, P. Effects of thermocycling on the margins of transitional acrylic resin crowns. J. Prosthet. Dent. 1991, 65, 642-646. 77. Hung, C. M.; Weiner, S.; Dastane, A.; Vaidyanathan, T. K. Effects of thermocycling and occlusal force on the margins of provisional acrylic resin crowns. J. Prosthet. Dent. 1993, 69, 573-577. 78. Ehrenberg, D. S.; Weiner, S. Changes in marginal gap size of provisional resin crowns after occlusal loading and thermal cycling. J. Prosthet. Dent. 2000, 84, 139148. 79. Kidd, E. A. Microleakage: a review. J. Dent. 1976, 4, 199-206. 80. ARMSTRONG, W. D.; SIMON, W. J. Penetration of radiocalcium at the margins of filling materials: a preliminary report. J. Am. Dent. Assoc. 1951, 43, 684-686. 81. PICKARD, H. M.; GAYFORD, J. J. Leakage at the Margins of Amalgam Restorations. Br. Dent. J. 1965, 119, 69-77.

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))!

82. MORTENSEN, D. W.; BOUCHER, N. E.,Jr; RYGE, G. A Method of Testing for Marginal Leakage of Dental Restorations with Bacteria. J. Dent. Res. 1965, 44, 5863. 83. Going, R. E. Microleakage around dental restorations: a summarizing review. J. Am. Dent. Assoc. 1972, 84, 1349-1357. 84. Trajtenberg, C. P.; Caram, S. J.; Kiat-amnuay, S. Microleakage of all-ceramic crowns using self-etching resin luting agents. Oper. Dent. 2008, 33, 392-399. 85. Lewinstein, I.; Chweidan, H.; Matalon, S.; Pilo, R. Retention and marginal leakage of provisional crowns cemented with provisional cements enriched with chlorhexidine diacetate. J. Prosthet. Dent. 2007, 98, 373-378. 86. Tjan, A. H.; Chiu, J. Microleakage of core materials for complete cast gold crowns. J. Prosthet. Dent. 1989, 61, 659-664. 87. Kutulakos, K. S.,E. A Theory of Specular and Refractive Shape By Light Path Triangulation. Microsoft Research Technology 2005. 88. Rohaly United states Patent 7,272,642, 2006. 89. 3M ESPE LAVA chairside oral scanner C.O.S 3M ESPE Technical Datasheet. 2009. 90. E4D official webpage http://www.e4dsky.com. 91. Christensen, G. J.; Child, P. L.,Jr Fixed prosthodontics: time to change the status quo? Dent. Today 2011, 30, 66, 68, 70-3. 92. Quadling,H.Quadling,M.Blair,A. United States Patent 0060900 A1, 2010. 93. Goodacre, C. J.; Garbacea, A.; Naylor, W. P.; Daher, T.; Marchack, C. B.; Lowry, J. CAD/CAM fabricated complete dentures: concepts and clinical methods of obtaining required morphological data. J. Prosthet. Dent. 2012, 107, 34-46. 94. Ishijima, T.; Caputo, A. A.; Mito, R. Adhesion of resin to casting alloys. J. Prosthet. Dent. 1992, 67, 445-449. 95. Ettinger, R. L.; Kambhu, P. P.; Asmussen, C. M.; Damiano, P. C. An in vitro evaluation of the integrity of stainless steel crown margins cemented with different luting agents. Spec. Care Dentist. 1998, 18, 78-83. 96. Baldissara, P.; Comin, G.; Martone, F.; Scotti, R. Comparative study of the marginal microleakage of six cements in fixed provisional crowns. J. Prosthet. Dent. 1998, 80, 417-422.

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)*!

97. Rosenstiel, S. F.; Gegauff, A. G. Improving the cementation of complete cast crowns: a comparison of static and dynamic seating methods. J. Am. Dent. Assoc. 1988, 117, 845-848. 98. Eames, W. B.; O'Neal, S. J.; Monteiro, J.; Miller, C.; Roan, J. D.,Jr; Cohen, K. S. Techniques to improve the seating of castings. J. Am. Dent. Assoc. 1978, 96, 432437. 99. Eliasson, S. T.; Lund, M. R. Improving marginal fit through finishing procedures. J. Indiana State Dent. Assoc. 1974, 53, 13-17. 100. Fusayama,T.Ide,K.Hosada,H Relief of Resistance of Cement of Full Cast Crowns. J Prosthet Dent 1964, 14, 95. 101. Ogawa, T.; Aizawa, S.; Tanaka, M.; Matsuya, S.; Hasegawa, A.; Koyano, K. Effect of water temperature on the fit of provisional crown margins during polymerization. J. Prosthet. Dent. 1999, 82, 658-661. 102. Lepe, X.; Bales, D. J.; Johnson, G. H. Retention of provisional crowns fabricated from two materials with the use of four temporary cements. J. Prosthet. Dent. 1999, 81, 469-475. 103. Ramkumar, V.; Sangeetha, A.; Kumar, V. Effect of water temperature on the fit of provisional crown margins during polymerization: An in vitro study. J. Pharm. Bioallied Sci. 2012, 4, S376-83. 104. Ivoclar Vivadent E-max Clinical Manual. 2008, Describes the material as well as the requirements of the preperation for the product. 105. L'Estrange, P. R.; Karlsson, S. L.; Odman, P.; Stegersjo, G.; Engstrom, B. Clinical evaluation of restoration margins by an endoscopic microscope. Aust. Dent. J. 1991, 36, 415-420. 106. Black, S.; Amoore, J. N. Measurement of forces applied during the clinical cementation of dental crowns. Physiol. Meas. 1993, 14, 387-392. 107. Christensen, G. J. Clinical and research advancements in cast-gold restorations. J. Prosthet. Dent. 1971, 25, 62-68. 108. Wendt, S. L.; McInnes, P. M.; Dickinson, G. L. The effect of thermocycling in microleakage analysis. Dent. Mater. 1992, 8, 181-184.

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*+! APPENDIX

Table A1 – Results of Marginal Discrepancies and Dye Penetration for Cerec®/ Telio® Interim Crowns

Vertical Horizontal Vertical Horizontal Component Component Component Component Crown Dye of Facial of Facial of Lingual of Lingual Identification Penetration Marginal Marginal Marginal Marginal Number /% Discrepancy Discrepancy Discrepancy Discrepancy / mm / mm / mm / mm

1

0.133

0.144

0.124

0.00

47.2

2

0.135

0.242

0.0997

0.0437

21.7

3

0.118

0.155

0.0721

000

49.6

4

0.295

0.144

0.124

0.00

28.9

5

0.111

0.174

0.0755

0.00618

23.8

6

0.215

0.203

0.00

0.00

27.8

7

0.180

0.191

0.0927

0.00

33.1

8

0.139

0.133

0.136

0.00

31.6

9

0.186

0.260

0.0968

0.0747

35.8

10

0.297

0.0989

0.127

0.0913

26.4

11

0.155

0.117

0.102

0.00

34.7

12

0.112

0.142

0.0498

0.00

33.9

13

0.143

0.199

0.0587

0.00

43.7

14

0.347

0.231

0.0450

0.178

37.2

15

0.174

0.243

0.0867

0.00

15.1

!

*"!

Table A2 – Results of Marginal Discrepancies and Dye Penetration for E4D®/ Paradigm® MZ100 Interim Crowns

Vertical Horizontal Vertical Horizontal Component Component Component Component Crown Dye of Facial of Facial of Lingual of Lingual Identification Penetration Marginal Marginal Marginal Marginal Number /% Discrepancy Discrepancy Discrepancy Discrepancy / mm / mm / mm / mm

16

-

-

-

-

-

17

0.968

0.127

0.118

0.00

59.5

18

0.141

0.145

0.0874

0.00

81.1

19

0.162

0.00

0.105

0.0556

79.4

20

0.556

0.00

0.121

0.0705

89.23

21

0.0433

0.0742

0.0989

0.0185

40.9

22

0.0683

0.0927

0.0752

0.00

69.5

23

0.137

0.111

0.0396

0.00

94.7

24

0.068

0.118

0.0841

0.045

89.8

25

0.186

0.143

0.0138

0.00

85.8

26

0.193

0.193

0.045

0.039

53.4

27

0.132

0.147

0.111

0.00

70.3

28

0.266

0.0866

0.112

0.0437

53.9

29

0.189

0.110

0.0630

0.00

75.0

30

0.135

0.108

0.175

0.00

70.9

!

*#!

Table A3 – Results of Marginal Discrepancies and Dye Penetration for Caulk® Resin Interim Crowns

Vertical Horizontal Vertical Horizontal Component Component Component Component Crown Dye of Facial of Facial of Lingual of Lingual Identification Penetration Marginal Marginal Marginal Marginal Number /% Discrepancy Discrepancy Discrepancy Discrepancy / mm / mm / mm / mm

31

0.297

0.0587

0.0376

0.00

13.15

32

0.136

0.117

0.0567

0.00

21.53

33

0.324

0.112

0.0941

0.461

76.1

34

0.451

0.259

0.180

0.144

36.1

35

0.391

0.144

0.149

0.105

30.0

36

0.174

0.137

0.156

0.228

38.3

37

0.403

0.167

0.0999

0.448

49.9

38

0.415

0.00

0.180

0.00

13.0

39

0.181

0.00

0.126

0.00

40.5

40

0.503

0.0371

0.133

0.208

30.3

41

0.364

0.114

0.0892

0.00

27.1

42

0.231

0.00

0.0859

0.486

33.9

43

0.346

0.236

0.295

0.149

11.5

44

0.00

0.00

0.00

0.00

29.6

45

0.200

0.113

0.198

0.111

22.0

!

*$!

Table A4 – Results of Marginal Discrepancies and Dye Penetration for Jet® Resin Interim Crowns Vertical Horizontal Vertical Horizontal Component Component Component Component Crown Dye of Facial of Facial of Lingual of Lingual Identification Penetration Marginal Marginal Marginal Marginal Number /% Discrepancy Discrepancy Discrepancy Discrepancy / mm / mm / mm / mm 46

0.0989

0.00

0.113

0.227

14.2

47

0.127

0.00

0.0691

0.00

12.1

48

0.150

0.00

0.158

0.116

7.91

49

0.125

0.0255

0.254

0.0927

16.6

50

0.131

0.00

0.122

0.0724

11.1

51

0.0874

0.00

0.130

0.360

9.89

52

0.188

0.00

0.0528

0.114

19.0

53

0.100

0.0825

0.0645

0.0691

14.1

54

0.230

0.00

0.106

0.127

14.6

55

0.129

0.00

0.110

0.00

17.1

56

0.209

0.00

0.0360

0.136

29.5

57

0.291

0.130

0.0637

0.176

62.7

58

0.120

0.0946

0.105

0.186

27.0

59

0.031

0.00

0.173

0.130

16.3

60

0.186

0.00

0.135

0.125

12.1

!

*%!

Table A5 – Re-measurement of Marginal Discrepancies in 12 Selected Interim Crowns.

Crown Identification Number

Vertical Component of Facial Marginal Discrepancy / mm

Horizontal Component of Facial Marginal Discrepancy / mm

Vertical Component of Lingual Marginal Discrepancy / mm

Horizontal Component of Lingual Marginal Discrepancy / mm

2

0.143

0.250

0.116

0.00

5

0.148

0.117

0.0961

0.00

13

0.138

0.193

0.0955

0.00

18

0.144

0.154

0.162

0.00

23

0.0677

0.169

0.0778

0.00

29

0.199

0.195

0.0914

0.00

32

0.130

0.136

0.148

0.00

36

0.202

0.129

0.185

0.190

41

0.284

0.0925

0.0413

0.00

47

0.137

0.00

0.0802

0.00

55

0.129

0.00

0.0748

0.0195

58

0.101

0.0963

0.0881

0.257