RETENTION OF CAD/CAM CROWNS LUTED WITH RESIN CEMENTS AND
RMGI
by
SHRUTI SUSHILKUMAR SONAVANE
DR. JOHN O. BURGESS (COMMITTEE CHAIR)
DR. AMJAD JAVED
DR. JACK E. LEMONS
DR. LANCE RAMP
DR. NATHANIEL C. LAWSON
A THESIS
Submitted to the graduate faculty of The University of Alabama at Birmingham,
in partial fulfillment of the requirements for the degree of
MS in Clinical Dentistry
BIRMINGHAM, ALABAMA
2015
i
Copyright by
Shruti Sushilkumar Sonavane
2015
RETENTION OF CAD/CAM CROWNS LUTED WITH RESIN CEMENTS AND
RMGI
SHRUTI SUSHILKUMAR SONAVANE
MS IN CLINICAL DENTISTRY
ABSTRACT
Objectives: To measure retention of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) and zirconia reinforced lithium disilicate (CELTRA™ DUO, Dentsply) copings
luted using resin cements and resin-modified glass ionomer cement.
Methods: 110 Extracted human, non-carious mandibular 2nd premolars (n=10) were
embedded in PVC cylinders with acrylic resin and placed into a lathe to produce a uniform crown preparation (22°-convergence & 3mm-height). Following the orientation
groove placement (69L bur), preparations were scanned and milled using a CEREC
3D/Sirona machine to produce e.max and CELTRA™ DUO crowns. Preparations were
imaged with a digital microscope (Keyence/VHX-600-20X) and the surface area of each
crown was calculated. IPS e.max crowns and CELTRA™ DUO crowns were cemented
using the cements as in Tables 1 & 2. Specimens were stored (distilled water/37°C/24h)
and thermocycled (10,000cycles/5-50°C/30secs) before debonding in tension at crosshead speed-5mm/min (INSTRON Model/5565). The bond strength was calculated by
dividing the failure load with preparation surface area. The CELTRA™ DUO and e.max
data were compared separately with 1-way ANOVA and Tukey post-hoc analysis (alpha=0.05).
Results: The simulated crown strength test results for e.max were: Calibra=4.89±2.35a;
ExpE(TE)=3.70±2.08a,b; ExpSE=3.18±2.03a,b RelyXLP=3.11±1.99a,b; ExpE(SelfEtch)=2.74±1.23a,b; Multilink=2.66±1.72a,b; RelyXU=2.65±1.46a,b; Reiii
lyXLP/HF=1.91±0.70b. For CELTRA™: Exp/S=4.73±2.45a; Exp/S/E=4.40±1.76a,b; RelyXLP/HF=3.34±1.65a,b, c; Exp=1.79±0.70b,c; and RelyXLP=0.95±0.58c. The ANOVA
showed some significant differences between groups (p=0.01) where the same letter denotes similar groups.
Conclusions: The Calibra material resulted in significantly higher retention with the than
RelyXLP/HF for the coping fabricated from e.max. The experimental resin cement with
silane when compared to Exp and RelyXLP resulted in significantly higher test retention
strength for the CELTRA™ DUO.
KEYWORDS: Adhesion, CAD/CAM, Biomaterials, Cements, Ceramics.
iv
DEDICATION
This thesis is dedicated to my husband, Sushil and my son, Dhruv for their continuous
support throughout my masters program.
This thesis is also dedicated to my parents for teaching me the value of knowledge, persistence and hard work, without which I would have never been where I am today.
v
ACKNOWLEDGMENTS
This project would not have been possible without the support of many people. I would
like to thank my mentor, Dr. John Burgess, for his outstanding guidance, patience, support and trust that he put in me throughout my masters.
I would also like to thank Dr. Lemons for making me think about the details and made
me realize that “Devil lies in the details”
I would like to thank Dr. Nathaniel Lawson for his smart ideas. I really appreciate him for
being good at everything he does.
I thank Dr. Lance C. Ramp for providing his statistical expertise and his timely
Responses.
I thank Dr. Amjad Javed, for their invaluable student friendly advices over the
period of my masters.
I would like to thank Mr. Preston Beck for his patience and his readiness to help everyone around him. His expertise in engineering has saved my day many times.
A special thanks to Ms. Rhonda Scott, for helping in all the paper work since my admission process till date.
vi
I would like to thank Kanchan Sawlani, Chinkai Lin, Latara Rogers, Rashmi Radhakrishanan, Ritika Bansal and Nan Xiang for wonderful company.
I would like to thank my husband, Sushil for constant encouragement, patience and support he has shown since we met. Special thanks to my son, Dhruv for willingly or unwillingly supporting me.
Special thanks to my family and my in-laws for their blessings and having faith in me
that I can balance family life with studies.
vii
TABLE OF CONTENTS
Page
Abstract...............................................................................................................................iii
Dedication............................................................................................................................ v
Acknowledgments .............................................................................................................. vi
List of Tables ....................................................................................................................... x
List of Figures..................................................................................................................... xi
List of Abbreviations ........................................................................................................xiii
INTRODUCTION ............................................................................................................... 1
Ceramics .............................................................................................................................. 3
Luting Agent ........................................................................................................................ 3
Various methods of bond strength testing ........................................................................... 4
Previous Crown-Tensile testing .......................................................................................... 5
OBJECTIVES AND HYPOTHESIS .................................................................................. 7
MATERIALS AND METHODS ........................................................................................ 8
Teeth Selection .................................................................................................................. 15
Teeth Mounting ................................................................................................................. 15
Standardized Tooth Preparation ........................................................................................ 18
Total Bonding Surface area Calculation............................................................................ 19
viii
Designing, Milling and Crystallization of Copings ........................................................... 21
Cementation of Copings .................................................................................................... 25
Storage, Thermocycle and Tensile Testing ....................................................................... 30
Statistical Analysis ............................................................................................................ 33
RESULTS .......................................................................................................................... 34
DISCUSSION.................................................................................................................... 38
LIMITATIONS ................................................................................................................. 44
CONCLUSIONS ............................................................................................................... 45
FUTURE DIRECTIONS ................................................................................................... 46
REFERENCES .................................................................................................................. 47
APPENDICES
A. IRB Approval .......................................................................................................... 51
ix
LIST OF TABLES
Table
Page
1. Materials
8
2. Groups for e.max
9
3. Groups for Celtra
12
4. Parameters for CAD/CAM Design and Milling Crystallization
22
5. Directions for Use of Resin Cement
25
6. Mode of failure
31
7. e.max Retention in MPa
34
8. Celtra Retention in MPa
35
9. SEM of Celtra
43
x
LIST OF FIGURES
Figure
Page
1. Flattening the cusps on model trimmer
15
2. Slow-speed handpiece with abrasive disc
16
3. Notching the roots with abrasive disc
16
4. Mandibular 1st Premolar with flattened and notched roots
16
5. Surveyor for mounting teeth
17
6. Centering the tooth using caliper
17
7. Centered tooth embedded in auto-polymerizing clear acrylic resin
17
8. Tooth preparation on lathe
18
9. Keyence- to calculate the total bonding surface area of the prepared tooth
19
10. Measurement of radii ‘r’ of top circle & ‘R’ of base circle
19
11. Measurement of areas of irregular shaped whole base
20
12. Truncated Cone
21
13. Spraying the prepared tooth with titanium dioxide powder for scanning
22
14. Cerec 3
23
15. e.max block inserted in Cerec 3
23
16. Inserting object fix putty in milled coping to stabilize the coping on the firing
stand
23
17. Programmat CS
24
18. Firing e.max copings
24
19. Etching with 5% HF
28
20. Application of bonding agent
29
xi
21. Silane application
29
22. Insertion of mixed cement
29
23. Cemented specimen under load of 2.5Kgs
30
24. Fixture for holding the specimen for testing
31
25. Specimen placed in fixture wrapped in rubber dam sheet
32
26. Specimen during tensile testing in Instron
32
27. e.max Retention
34
28. Celtra Retention
35
29. Failure Mode (%) for e.max
36
30. Failure Mode (%) for Celtra
37
31. Fractured Celtra crown during testing
42
xii
LIST OF ABBREVIATIONS
CAD/CAM
Computer Assisted Designing/ Computer Assisted Machining
Celtra
Celtra™ Duo
e.max
IPS e.max (CAD)
HF
Hydrofluoric acid
RMGI
Resin Modified Glass Ionomer Cement
ZLS
Zirconia Reinforced Lithium Silicate
xiii
INTRODUCTION
Recent advancements in dentistry have been driven by a demand for esthetic and natural
appearing restorations. Improvements in the formulation and fabrication of dental ceramics have resulted in escalated applications of these esthetic materials.1, 2 During the same
time, demand for metal-ceramic restorations has dropped significantly, due to esthetic
limitations and reactions or sensitivity to various metals.3-5These drawbacks, along with
the high material and labor costs associated with metal substrate fabrication (particularly
noble metals), have prompted the development of new ceramic systems with a high
strength, precision fit and superior esthetic and optical properties not found for metalceramics systems.6-8
One of the most prolific dental ceramics is IPS e.max CAD, a lithium disilicate material
that exhibits superior esthetics and durability, combined with clinically satisfactory physical properties. When fabricated to full-contour, the monolithic structure is one of the
most robust ceramic systems tested to-date.7 The opalescence, translucency and light diffusion properties of IPS e.max were all designed to replicate natural tooth structure for
beauty and undetectable restorations. Massive casting on a continuous manufacturing
process (based on glass technology) is used to produce the blocks. This new technology
uses optimized processing parameters, which prevent the formation of defects (pores,
1
accumulation of pigments, etc.) in the bulk of the ingot.9 Partial crystallization ensures
that the blocks can be processed in a crystalline intermediate phase, which enables fast
machining with CAD/CAM systems (blue, translucent state).10 The partial crystallization
process leads to a formation of lithium metasilicate crystals Li2 SiO3, which are responsible for the material's processing properties, relatively high strength and edge stability.
Following the milling procedure, the restorations are tempered and thus reach the fully
crystallized state. In the course of this process, lithium disilicate crystals (Li 2Si2O5) are
formed, which impart the ceramic restoration with the desired high strength9.
The crystallization process of IPS e.max CAD, however, requires about 21-30 minutes.
Due to a demand for reduced chair-side time without compromising esthetics, Caulk
Dentsply patented a zirconia reinforced lithium silicate (ZLS)-based ceramic
(CELTRA™ Duo). Unlike IPS e.max CAD, this material possesses sufficient strength to
withstand intra-oral forces and acceptable esthetics without heat treatment.
Ceramic restorations also benefit from technologies that automate aspects of their fabrication11. In other words, these materials are fabricated by machines rather than relying on
the hand-layered fabrication method used for dental porcelain. Automation allows less
reliance on the skill of the individual ceramist as well as greater homogeneity and lower
probability of defects within the material itself.12 In addition, ceramic restorations
demonstrate optical properties superior to metal-ceramic restorations.13 Ceramic materials are also the major type of material used with in-office digital dentistry. The evolution
of
digital
technology
and
computer-aided
2
design/computer-aided
manufacture
(CAD/CAM) systems now offer the opportunity to avoid traditional, analog impressions,
including the time, expense, and handling limitations associated with them.14 Intraoral
scanners have the potential to offer excellent accuracy with a more comfortable experience for the patient and more efficient workflow for the office.15
Ceramics
In dentistry, ceramics are widely used due to their ability to imitate the optical characteristics of enamel and dentin and their biocompatibility and chemical durability.16 There
are three main types of dental ceramics: (1) predominantly glassy materials, (2) particlefilled glasses, and (3) polycrystalline ceramics.16 Highly esthetic dental ceramics are predominantly glassy, and higher strength substructure ceramics are generally crystalline.
Hybrid combinations have also been developed. The history of development of substructure ceramics involves an increase in crystalline content to fully polycrystalline. IPS
e.max CAD is a type of particle-filled glass, while CELTRA™ Duo is a hybrid zirconiareinforced lithium silicate.
Luting Agents
The luting agents used for indirect restorations mainly have to fulfill three requirements:
(1) to fill the space between the indirect material and the prepared tooth; (2) to keep the
restoration in place (retention) and prevent dislodging; and (3) to provide adequate aesthetical conditions for the indirect restoration.17 Bonding of ceramic to dental tissue is
3
based on the adhesion of luting cement to the ceramic substrate, together with the adhesion of luting cement to enamel and/or dentin. Adhesive cementation is recommended for
ceramic restorations
18, 19
particularly for over-tapered or short preparations. It has been
reported that a long-term durable bond to the ceramics is imperative for a long-term successful restoration.20, 21 For bonding to silica-based ceramics, hydrofluoric acid has been
used to etch the restoration and silane applied to serve as a chemical link between the
ceramic and the resin cement.22, 23 Methods for bonding to zirconia, on the other hand,
include the use of phosphate monomer-containing (MDP) composite resins, or silica coating and silane application24. Inokoshi et al
25
recommended techniques which combine
mechanical and chemical surface pre-treatments for zirconia. The introduction of Celtra
Duo presented a unique bonding challenge. An effective method of bonding to novel
zirconia reinforced- lithium silicate needs to be established.
Various Methods Of Bond Strength Testing
Bond strength testing methods used in dentistry can be broadly classified as shear and
micro-tensile testing. A disadvantage reported for shear and micro-tensile bond strength
tests is that they do not take into account the complex geometry of a tooth preparation as
the luting agent is only bonded to flat surfaces. The ratio of bonded to non-bonded surfaces (Configuration factor or C-factor)26 is much higher in crowns luted onto abutments
or dies than in composite or ceramic cylinders luted onto flat surfaces. A laboratory study
has shown that the C-factor influences the bond strength of the adhesive significantly27.
4
This might explain why bond strength data of 1–10 MPa are found in crown retention
strength investigations compared to 20–40 MPa in shear bond strength tests.28
Previous Crown-Tensile testing
Influence of tooth preparation characteristics
Retention of the single-unit crowns is influenced by the taper angle-–the angle of convergence between the opposing axial walls. The retention of bonded crowns has been shown
to depend on the taper angle: the lower the taper angle, the higher the retention29-33. The
maximum retention is obtained between 60 and 120 taper29. In practice, ideal axial wall
convergence may not be routinely obtained. Studies have reported mean taper angles
ranging from 30 to 260 34.
Influence of type of cement
Several factors have been shown to influence the retention of metal-ceramic restorations,
including the preparation convergence and height, and the type of cement. A recent study
confirmed that neither the surface conditioning type, nor the taper angle affected the retentive strength of IPS e.max Press single-unit crowns when bonded adhesively35. Metalceramic crowns cemented with resin cements, showed higher retention than conventional
cements.3, 36-43 Dental adhesives and cements are a complex mixture of ingredients designed to provide retention for a variety of materials to tooth structure. These materials
must interact with enamel, dentin, and the restorative material. The development of 4META system has led to a wide variety of adhesives and cements over the past dec-
5
ades—all of which have consisted of the same essential ingredients and have provided
outstanding consistency and predictability of bonding to dentin44, 45
6
OBJECTIVES AND HYPOTHESIS
The objectives of this dissertation are
1. To measure retention of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) copings luted using resin cements and resin-modified glass ionomer cement with various
surface treatments.
2. To measure retention of zirconia reinforced lithium disilicate (CELTRA™ DUO,
Dentsply) copings luted using resin cements and resin-modified glass ionomer cement with various surface treatments.
The null hypotheses of the study are:
1. Retention of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) copings is not influenced by the type of cement and various surface treatments.
2. Retention of copings of zirconia reinforced lithium disilicate (CELTRA™ DUO,
Dentsply) is not influenced by the type of cement and various surface treatments.
7
MATERIALS AND METHODS
The materials, groups and methods for this study are summarized in the following Tables
and associated descriptions.
Table 1: Materials
Material
Manufacturer
e.max
Ivoclar
Celtra Duo
Caulk Dentsply
Adhesive resin cement
experimental
Caulk Dentsply
130916
03/2014
Prime & Bond Elect
Caulk Dentsply
130811
08/2016
Calibra Resin cement
Caulk Dentsply
130417
10/2014
Caulk Dentsply
130603
06/2015
Caulk Dentsply
Adhesive -121031
Activator – 130805
08/2014
08/2015
Scotchbond Universal
3M ESPE
521198
06/2015
RelyX Ultimate
3M ESPE
521894
09/2014
Monobond Plus
Ivoclar
626221
04/2015
Multilink Automix
Ivoclar
Primer – S02167
Adhesive – S06441
07/2014
08/2014
RelyX Luting Plus
Ivoclar
N484102
01/2015
Calibra Silane coupling
agent
XP Bond/Self-cure Activator
Lot No
8
S37918, S33811,
S53671
TWA#61, TWA#58,
18016483
Expiration
2028
Table 2: Groups for e.max
Group
Intaglio Surface
Etch
Multilink
Silane
5%HF
Tooth Treatment
Bond
Monobond Plus
Multilink Primer A/B
(Self-Etch)
RelyXU
5%HF
Scotch Bond Universal
Scotch Bond Universal
(Self-Etch)
Calibra
5%HF
Silane
XP Bond/ Self Cure acti-
XP Bond/Self Cure acti-
vator
vator (Total-Etch)
ExpSE
5%HF
ExpE
5%HF
P&B Elect (Self-Etch)
ExpE (TE)
5%HF
P&B Elect (Total-Etch)
RelyXLP/Etch
5%HF RelyXLP
Multilink:
Silane
P&B Elect (Self-Etch)
a. Tooth preparation. Apply Multilink Primer A/B for 20 seconds. Air
dry.
b. Etch e.max coping with 5% HF for 20 seconds, rinse and ultrasonically clean. Air dry. Apply Monobond Plus for 60 seconds and air
dry. Deliver Multilink Automix to e.max coping. Allow to self-cure
under seating force of 2.5Kgs. Debond after thermocycling for 10,000
times, between 5° C and 50°C with 30 seconds dwell time.
9
RelyXU:
a. Tooth preparation. Apply Scotchbond Universal, agitate for 20
seconds. Air dry.
b. Etch e. max coping with 5% HF for 20 seconds, rinse and ultrasonically clean. Air dry. Apply Scotchbond Universal for 20 seconds agitate and air dry. Deliver RelyX Ultimate to e. max coping. Allow to
self-cure under seating force of 2.5Kgs. Debond after thermocycling
for 10000 cycles (between 5° C and 50° C with 30 seconds dwell
time).
Calibra:
a. Tooth preparation. Etch with Caulk Etching Gel for 15 seconds.
Rinse well and blot dry. Apply XP Bond/Self-cure Activator (1:1) for
20 seconds. Air dry.
b. Etch e.max coping with 5% HF for 20 seconds, rinse and ultrasonically clean. Air dry. Apply Caulk Silane coupling agent for 60 seconds. Air dry. Apply XP Bond/Self-cure Activator (1:1) for 20 seconds. Air dry. Insert mixed Calibra resin cement into e.max coping.
Allow to self-cure under seating force of 2.5Kgs. Debond after thermocycling for 10,000 cycles (between 5° C and 50°C with a 30 seconds dwell time)
ExpSE:
a. Tooth prep. Apply Prime & Bond Elect and agitate for 20 seconds.
Air dry for 5 seconds. Light cure for 20 seconds with 3M ESPE Elipar S10 with output of 878.5mW/cm2.
10
b. Etch e.max coping with 5% HF for 20 seconds, rinse and ultrasonically clean in distilled water. Air dry. Apply Caulk Silane coupling
agent for 60 seconds. Air dry. Insert mixed Experimental Adhesive
Resin Cement R1096 to e.max coping. Allow to self-cure under seating force of 2.5Kgs. Debond after thermocycling for 10000 times (between 5° C and 50° C with 30 seconds dwell time)
ExpE:
a. Tooth Preparation: Apply Prim & Bond Elect and agitate for 20
seconds, air dry for 5 seconds and light cure for 20 seconds with 3M
ESPE Elipar S10 with output of 878.5mW/cm2.
b. Etch e.max coping with 5% HF for 20 seconds, rinse and ultrasonically clean in distilled water. Air dry. Deliver Experimental Adhesive
Resin Cement R1096 to e.max coping. Allow to self-cure under seating force of 2.5Kgs. Debond after thermocycling for 10000 times (between 5° C and 50° C with 30 seconds dwell time)
ExpE(TE)
a. Tooth preparation. Etch with Caulk Etching Gel for 15 seconds
with agitation. Rinse well and blot dry. Apply Prime & Bond Elect;
agitate for 20 seconds and air dry for 5 seconds. Light cure 20 seconds with 3M ESPE Elipar S10 with output of 878.5mW/cm2.
b. Etch e. max coping with 5% HF for 20 seconds, rinse and ultrasonically clean in distilled water. Air dry, insert mixed (Experimental
Adhesive Resin Cement R1096) to e. Max coping. Allow the cement
to self-cure under a seating force of 2.5Kgs and debond after thermo-
11
cycling for 10,000 cycles (between 5° C and 50° C with 30 seconds
dwell time)
RelyXLP/Etch:
a. Tooth preparation. Dry the tooth surface while keeping it moist.
b. Etch e.max coping with 5% HF for 20 seconds, rinse and ultrasonically clean in distilled water for 10 mins. Air dry. Deliver mixed RelyX luting plus to e.max coping. Allow to self-cure under seating
force of 2.5Kgs. Debond after thermocycling for 10000 times (between 5° C and 50° C with 30 seconds dwell time)
RelyXLP:
a. Tooth preparation. Dry the tooth surface while keeping it moist.
b. Air dry e.max copings. Deliver mixed RelyX luting plus to e.max
coping. Allow to self-cure under seating force of 2.5Kgs. Debond after thermocycling for 10000 times (between 5° C and 50° C with 30
seconds dwell time)
Table 3: Groups for Celtra
Group
Intaglio Surface
Etch
Silane
Tooth Treatment
Bond
Exp
5%HF
ExpS
5%HF
Silane
ExpSE
5%HF
Silane
P&B Elect
P&B Elect (Self-Etch)
RelyXLP/Etch
5%HF RelyXLP
P&B Elect (Self-Etch)
P&B Elect (Self-Etch)
12
Exp:
a. Tooth prep. Apply Prime & Bond Elect and agitate for 20 seconds.
Air dry for 5 seconds. Light cure for 20 seconds with 3M ESPE Elipar S10 with output of 878.5mW/cm2.
b. Etch Celtra coping with 5% HF for 20 seconds, rinse well for 20
seconds and ultrasonically clean for 10 minutes. Air dry for 10 seconds. Insert mixed Experimental Adhesive Resin Cement R1096 to
Celtra coping. Allow to self-cure under seating force of 2.5kgs.
Debond after thermocycling between 5°C and 50°C with dwell time
of 30 seconds for 10000 cycles.
ExpS:
a. Tooth prep. Apply Prime & Bond Elect and agitate for 20 seconds.
Air dry for 5 seconds. Light cure for 20 seconds with 3M ESPE Elipar S10 with output of 878.5mW/cm2.
b. Etch Celtra coping with 5% HF for 20 seconds, rinse well for 20
seconds and ultrasonically clean for 10 minutes in distilled water. Air
dry for 10 seconds. Apply Caulk Silane coupling agent for 60 seconds and air dry for 5seconds. Insert mixed Experimental Adhesive
Resin Cement R1096 to Celtra coping. Allow to self-cure under seating force of 2.5 Kgs. Debond after thermocycling for 10000 times
(between 5° C and 50° C with 30 seconds dwell time)
ExpSE:
a. Tooth prep. Apply Prime & Bond Elect and agitate for 20 seconds.
Air dry for 5 seconds. Light cure for 20 seconds with 3M ESPE Elipar S10 with output of 878.5mW/cm2.
13
b. Etch Celtra coping with 5% HF for 20 seconds, rinse well for 20
seconds and ultrasonically clean for 10 minutes. Air dry for 10 seconds. Apply Caulk Silane coupling agent for 60 seconds. Air dry for
5seconds. Apply Prime & Bond Elect and agitate for 20 seconds. Air
dry for 10 seconds. Light cure for 20 seconds with 3M ESPE Elipar
S10 with output of 878.5mW/cm2. Deliver Experimental Adhesive
Resin Cement R1096 to Celtra coping. Allow to self-cure under seating force of 2.5 Kgs. Debond after thermocycling for 10000 times
(between 5° C and 50° C with 30 seconds dwell time)
RelyXLP/Etch:
a. Tooth preparation. Dry the tooth surface while keeping it moist.
b. Etch Celtra coping with 5% HF for 20 seconds, rinse and ultrasonically clean in distilled water for 10 mins. Air dry. Deliver mixed RelyX luting plus to e.max coping. Allow to self-cure under seating
force of 2.5Kgs. Debond after thermocycling for 10000 times (between 5° C and 50° C with 30 seconds dwell time)
RelyXLP:
a. Tooth preparation. Dry the tooth surface while keeping it moist.
b. Air dry Celtra coping. Deliver mixed RelyX luting plus to e.max
coping. Allow to self-cure under seating force of 2.5Kgs. Debond after thermocycling for 10000 times (between 5° C and 50° C with 30
seconds dwell time)
14
Teeth Selection
Mandibular second premolar teeth, freshly extracted for orthodontic reasons, were collected from the Oral and Maxillofacial Surgery Department of the UAB School of Dentistry. One hundred and ten (110) mature teeth without caries, non-carious cervical lesions and cracks were selected. Teeth were examined for cracks under 2.5X loupes.
Teeth Mounting
The roots of the selected teeth were notched with a rotating disc on a slow-speed handpiece and the occlusal surfaces were ground flat on the model trimmer. For mounting, the
teeth were centered in Teflon cylinders with the help of a surveyor and digital caliper and
then embedded in clear auto-polymerizing acrylic resin (Yates Motloid, USA). The
methods are shown in Figures 1-8.
Figure 1: Flattening the cusps on model trimmer
15
Figure 2: Slow-speed handpiece with abrasive disc
Figure 3: Notching the roots with abrasive disc
Figure 4: Mandibular 1st Premolar with flattened and notched roots
16
Figure 5: Surveyor for mounting teeth
Figure 6: Centering the tooth using caliper
Figure 7: Centered tooth embedded in auto-polymerizing clear acrylic resin
17
Standardized Tooth Preparation
After complete curing of the acrylic resin, the sample was fixed into a lathe for precise
uniform reduction with diamond cutting tools to produce a uniform coping preparation
with exact taper, diameter and fit. The teeth were prepared to uniform dimensions (22°
total taper using 846.11.025 HP medium flat end taper diamond bur (Brasseler, USA), 3
mm preparation height using X 889 diamond bur). An orientation groove was placed into
the occlusal surface of preparation by hand using a 69 L bur and high-speed handpiece.
Teeth were kept moist prior to bonding.
Figure 8: Tooth preparation on lathe
18
Total Bonding Surface Area Calculation
The bonding surface area of the prepared surface was calculated under 20X in Keyence
as shown in Figures 9-12.
Figure 9: Keyence- to calculate the total bonding surface area of the prepared tooth
Figure 10: Measurement of radii ‘r’ of top circle & ‘R’ of base circle
19
Figure 11: Measurement of areas of irregular shaped whole base
In order to calculate the bonding surface area, the lateral walls, occlusal table, and margin
width were all measured separately. The bonding area was calculated using the formula:
Bonding area = lateral surface area of truncate cone + area of top circle of truncated cone
+ (Difference between area of base and bottom circle of truncated cone)
Each of these areas were calculated as described below:
1. Lateral surface area of the truncated cone is calculated by formula= π(R + r) S sq.
units
2. The area of top circle of truncated cone was measured as πr2. This area represents the
occlusal table of the preparation.
20
3. The base of the preparation was measured with a function on the Keyance microscope.
The bottom circle of the truncated cone was measured as πR2. The difference between
these values represents the width of the preparation margin.
Figure 12: Truncated Cone
Where r=radius (of top circle) and R (of base circle), h=height and s=slant height and π=
3.14. This area represents the lateral wall of the preparation. An excel sheet was prepared
for the calculations.
Designing, Milling and Crystallization of Copings
Seventy (70) e.max and forty (40) Celtra copings were milled using the Cerec 3 (Sirona)
CAD-CAM machine as shown in Figures 15-18. The parameters for CAD/CAM design
and milling are given in Table 4.
21
Table 4: Parameters for CAD/CAM Design And Milling
Proximal contacts strength
75µm
Occlusal contacts strength
25 µm
Occlusal offset
0 µm
Margin thickness
0 µm
Minimal thickness (occlusal)
1000 µm
Minimal thickness (radial
700 µm
Minimal thickness (Veneer)
500 µm
Adhesive gap
20 µm
Spacer
0 µm
Scan step width
3 µm
Figure 13: Spraying the prepared tooth with titanium dioxide powder
For scanning
22
Figure 14: Cerec 3
Figure 15: e.max block inserted in Cerec 3
The e.max copings were crystallized using Programmat CS (Ivoclar, Vivadent, Schaan),
with the following parameters. Before crystallization the e.max copings were filled with
Object Fix putty (Ivoclar) for stabilization on the stand during crystallization. The parameters for program P1 of Programmat CS were used.
23
Figure 16: Inserting object fix putty in milled coping to stabilize the coping on the firing
stand
Figure 17: Programmat CS
Figure 18: Firing e.max copings
24
Cementation of Copings
The e.max and Celtra copings were then individually tried on the tooth preparations and
an explorer was used to ensure there were no marginal defects. The copings were cemented with the appropriate primers and cements as was listed inTable1. The cements
were mixed following the manufacturers’ directions listed in Table 6 for the groups listed
in Tables 2 and 3. A 2.5Kgs weight placed on the cemented coping until the cement set.
Table 5: Directions for Use of Resin Cement
3M ESPE RelyX™ Ulti- Clean the interior surface of the coping with 5% hydroflumate
oric acid for 20secs, rinse thoroughly with water for
15secs and air dry. Apply Scotchbond Universal Adhesive; allow it to react for 20secs, air dry for 5secs. Attach
the mixing tip, squeeze out and discard a peppercorn-size
quantity of RelyX Ultimate until evenly mixed paste in a
homogeneous color flows out of the tip. Wet the entire
internal surface of restoration evenly with RelyX Ultimate. Seat the restoration and stabilize long enough for
the cement to fully set. Remove excess.
Ivoclar Vivadent
tilink® Automix
Mul- Etch the interior surface of coping with 5% hydrofluoric
acid for 20 seconds. Thoroughly rinse the restoration with
water spray and dry with oil-free air. Apply Monobond-S
to the surfaces with a microbrush and let react for 60 se-
25
conds. Disperse it with a strong stream of air. Mix the two
Multilink Primer liquids A and B in a 1:1 mixing ratio.
The mixed Primer A/B is solely self-curing and does not
need to be protected against light, but it must be applied
within 10 minutes. Apply the mixed Multilink Primer A/B
to the prepared tooth surface using a microbrush – starting
from the enamel and scrubbing with slight pressure for 15
seconds. A reaction time of 30 seconds is recommended
on the enamel and 15 seconds on the dentin. The applied
primer is subsequently dried with water- and oil-free air.
As the Primer is solely self-curing, no light curing is necessary. Place a new automix tip on the syringe. Dispense
Multilink from the automix syringe and apply Multilink
Automix directly to the inner surface of the restoration.
Seat the restoration in place and fix/hold. Remove the
excess material.
Experimental
adhesive Clean the internal surface of the restoration with Caulk®
resin cement R1096
34% Tooth Conditioner Gel (34% phosphoric acid) for 30
seconds, rinse thoroughly with water for 20 seconds and
air-dry. Directly apply the silane to the clean internal surface of the coping and air-dry. Remove syringe cap. Dispense and discard a small amount of material from the
dual-barreled syringe. Be sure material is flowing freely
26
from both ports. Holding syringe vertically, carefully wipe
away excess so base and catalyst do not cross contaminate
and cause obstruction of the ports. Save syringe cap for
replacement following use. Install a mixing tip on the cartridge by lining up the v-shaped notch on the outside of
the mixing tip with the V-shape notch on the syringe
flange. Turn colored mixing tip cap 90 degrees in a
clockwise direction to lock in place on syringe. Gently
depress syringe plungers to begin the flow of material.
DO NOT USE EXCESSIVE FORCE. Dispense a small
amount through the mixing tip onto a mixing pad and discard. Apply a uniform layer of cement on the entire internal surface of the restoration directly from the mixing tip.
At room temperature, R1096 Esthetic Resin Cement, in
either viscosity, offers a minimum work time of 2
minutes. A gentle rocking or vibratory motion was used to
insure optimal seating. Protect restoration from contamination and movement until the final set of the cement (till
completion of light curing). Remove excess cement.
Dentsply Caulk Calibra® Microetching (sandblasting) with 50µ alumina (or hyEsthetic Resin Cement
drofluoric acid chemical etching of the internal surfaces of
a ceramic restoration) is recommended. Clean the internal
surface of the restoration with Caulk® 34% Tooth Condi-
27
tioner Gel (34% phosphoric acid). Apply for 30 seconds,
rinse thoroughly with water for 20 seconds and air-dry.
Clean the prepared tooth surface with water and apply
adhesive, light cure. Attach supplied needle tip to end of
the Calibra® Silane Coupler syringe. Silane agent should
express easily, one drop at a time. Apply the silane to the
etched, clean internal surface of the restoration and airdry. Dispense Calibra® Esthetic Resin Cement base paste
from the syringe onto a clean mixing pad. Dispense an
equal amount of the desired viscosity of catalyst paste;
mix the cement for 20-30 seconds. Apply a uniform layer
of cement on the entire internal surface of the restoration.
Seat the restoration with gradual pressure. Remove excess
cement.
The procedures for cementation are shown in Figures 19-23.
Figure 19: Etching with 5% HF
28
Figure 20: Application of bonding agent
Figure 21: Silane application
Figure 22: Insertion of mixed cement
29
Figure 23: Cemented specimen under load of 2.5Kgs
Storage, Thermocycle And Tensile Testing
Excess cement was carefully removed and the copings stored in a moist zip lock bag for
24 hours at 37°C, thermocycled for 10,000 cycles between 5-500C with dwell time of 30
seconds before debonding. The specimens were placed in a special fixture (INSTRON
Model no: 5565) and loaded in tension at a crosshead speed of 5 mm/min until debonding. The force (N) of debonding was recorded. The retention force was calculated in MPa
by the formula:
Retention (MPa)=
Debonding Force (N)
Total Bonding Surface area of Preparation (mm2)
Note—Pascal= N/m2
Examination of the failure site was made optically with Keyance at 100 X and categorized according to 41Table 7. The test apparatus is shown in Figures 24-26.
30
Table 6: Mode of failure
Category
Description
Category 1
Cement mainly on prepared tooth (over 75%)
Category 2
Cement on both crown and tooth (between 25 and 75%)
Category 3
Cement mainly on crown (over 75%)
Category 4
Fracture of tooth without crown separation
Category 5
Fracture of Crown
Figure 24: Fixture for holding the specimen for testing
31
Figure 25:Specimen placed in fixture wrapped in rubber dam sheet
Figure 26: Specimen during tensile testing in Instron
32
Statistical Analysis
A Levine’s test of homogeneity was used to determine that all groups demonstrated a
normal distribution of variance. A 1-way ANOVA performed to compare differences
between bonding procedures for e.max was significant. A Tukey HSD post-hoc analysis
was used to compare groups. A separate 1-way ANOVA performed to compare differences between bonding procedures for Celtra was also significant. A Tukey HSD posthoc analysis was used to compare groups.
33
RESULTS
The test results for the simulated crown removal tests are summarized in Tables 8 and 9
and Figures 27 and 28. The mean values of crown retention ranged from 0.95 (RelyXLP
with Celtra) to 4.89 MPa (Calibra with e.max) 10000 thermal cycles (5°C and 50°C). The
IPS e.max when cemented with Calibra showed the highest bond strength, however it
was not significantly different from other groups except for RelyX Luting without etchant. CELTRA™ Duo showed highest bond strength when used with Experimental Resin
cement with silane, however it was not significantly different from other groups except
for RelyX Luting with etchant or when using Experimental resin cement alone.
Table 7: e.max Retention in MPa
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Av
SD
Multilink
RelyXU
Calibra
ExpSE
ExpE
ExpE(TE)
RelyXLP/
Etch
RelyXLP
0.98
2.30
1.26
4.78
4.34
5.04
0.50
4.49
2.17
0.79
2.66
1.72
4.28
2.57
4.42
3.03
0.64
3.00
0.80
1.34
4.85
1.60
2.65
1.46
7.88
6.59
3.94
4.60
7.08
2.11
8.57
2.95
3.59
1.59
4.89
2.35
5.08
7.49
1.78
1.80
4.54
0.83
3.63
4.02
1.27
1.38
3.18
2.03
4.62
2.05
2.10
4.49
4.26
2.84
1.20
2.03
1.21
2.63
2.74
1.23
1.49
1.86
3.89
4.18
7.05
6.80
5.08
4.01
0.82
1.84
3.70
2.08
2.75
0.98
1.72
1.65
2.46
1.86
5.49
4.83
2.63
0.76
1.91
0.70
3.11
1.99
34
e.max Retention
8.00
7.00
6.00
4.89
MPa
5.00
3.70
4.00
3.00
3.18
2.66
3.11
2.74
2.65
1.91
2.00
1.00
0.00
Figure 27: e.max Retention
Table 8: Celtra Retention in MPa
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Av
SD
Exp
ExpS
ExpSE
RelyXLP/Etch
RelyXLP
0.99
1.07
1.71
0.91
2.31
1.54
1.92
3.21
2.56
1.66
1.79
0.70
3.87
6.67
1.38
8.64
5.77
1.40
2.00
4.26
5.65
7.65
4.73
2.45
4.93
7.21
5.62
2.25
6.77
2.62
2.02
3.29
3.98
5.35
4.40
1.76
3.77
3.79
1.08
5.52
2.53
1.21
0.82
1.48
1.24
0.00
3.34
1.65
0.95
0.58
35
Celtra Retention
8.00
7.00
6.00
4.73
MPa
5.00
4.40
4.00
3.00
2.00
3.34
1.79
0.95
1.00
0.00
Exp
ExpS
ExpSE
RelyXLP/Etch
RelyXLP
Figure 28: Celtra Retention
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Multilink
1-on tooth
RelyXU
2-Mixed
Calibra
ExpSE
3-on Coping
ExpE
ExpE(TE) RelyXLP/Etch
4-Tooth Fracture
Figure 30: Failure Mode (%) for e.max
36
RElyXLP
5-Coping Fracture
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Exp
1-on tooth
ExpS
2-Mixed
ExpSE
3-on Coping
RelyXLP/Etch
4-Tooth Fracture
Figure 31: Failure Mode (%) for Celtra
37
RElyXLP
5-Coping Fracture
DISCUSSION
Crown retention is known to be influenced by a number of different parameters: the
abutment size and surface roughness46, 47, the total convergence angle of the walls of the
abutment33, and the cements33 used for luting contribute significantly to the performance
of the restorations.47 As new cements and ceramic materials develop, it is important to
measure and compare the crown retention produced by these cements compared to other
more clinically established materials.
The most common laboratory tests which assess the adhesive properties of a luting agent
are shear, tensile, microtensile or push-out 28 bond strength tests. The advantages of bond
strength tests are reproducibility and ease of conducting the test. The drawbacks is that
the bond strength testing does not reflect the clinical situation where the thixotropic cement applied under pressure during crown insertion exhibits flow and lower viscosity
permitting it to bond differently than a passive bonding test to a flat prepared tooth.
Therefore, crown tensile testing procedures were developed to more closely simulate the
clinical procedure.28
Dental luting cements play a vital role in the success of indirect restorations. The primary
function of the luting cement is to fill the space between the prepared tooth and indirect
restoration, in addition to mechanically or chemically bonding the restoration to the preparation to prevent dislodgement during function. A final property is to enhance the color
38
of the esthetic all ceramic restoration 17, 48, 49. Resin cements have gained popularity in the
dental market during recent years due to high compressive and tensile strengths, low solubility and favorable esthetic qualities. In addition, in vitro and in vivo studies suggest
that resin bonding helps diffuse stress and limit crack propagation on the internal aspect
of porcelain restorations20. However, they are expensive and have the disadvantages of
being technique sensitive, easily contaminated during multiple step application procedures and difficult and time consuming during clean-up50. They can be categorized based
on the bonding process as: (a) Total etch adhesive resin cements (b) Self-etch adhesive
resin cements and (c) Self-adhesive resin cements.
Restoration retention has been shown to depend on many factors. Macromechanical retention is mainly determined by the configuration of the crown preparation: (1) convergence angle; (2) surface area; (3) apical-coronal height; (4) and auxiliary retention devices such as pinhole, grooves or notches17, 32. In addition, some properties of the luting
agents which may prevent restoration dislodgement are: higher flexural strength51; lower
shrinkage, increased water uptake and cement expansion can improve retention52-54
In the present study, the influence of different surface treatments and luting agents were
studied. The mean values of crown retention ranged from 0.95 MPa (RelyXLP with
Celtra) to 4.89 MPa (Calibra with e.max) after 10,000 thermal cycles (5°C and 50°C).
39
The groups can be arranged in descending order as below
For e.max:
Calibraa=4.89±2.35>ExpE(TE)=3.70±2.08>ExpSE=3.18±2.03>RelyXLP=3.11±1.99
>ExpE=2.74±1.23>Multilink=2.66±1.72>RelyXU=2.65±1.46>RelyXLP/Etchb=
1.91±0.70.
For Celtra:
ExpSa=4.73±2.45>ExpSE=4.40±1.76>RelyXLP/Etch=3.34±1.65>
c
Expb,
=1.79±0.70>RelyXLPc=0.95±0.58.
The retention values in this study are in agreement with those of other studies on cement
luting and zirconia ceramic.33, 55
Retention strength in the present study had lower values than the previous studies.43, 56-58
The use of a different ceramic, the treatment of the ceramic crown intaglio surface, the
aging conditions, the degree of convergence, the surface area measurement, and the type
of cement were all different from previous studies. Palacios
43
et al and Ernst
56, 57
et al
used a lower degree of total occlusal convergence (5 and 10 degrees) than the 22 degrees
in the present study. As the pull-off test of crowns is supposed to be a clinically relevant
test, clinically relevant preparation parameters should be chosen. A convergence angle
that reflects the clinical situation should be chosen. Studies, which evaluated the convergence angle of casts produced of clinical cases, concluded that the mean angle was about
20◦59.
40
The lower angle of draw may increase the retention resistance, regardless of the type of
cement.60 The current study, with a greater angle of prepared total occlusal convergence,
may better assess the contribution of the cement and surface treatment to the retention of
crowns.41, 42 Also, zirconia was used in the previous studies, while in present study lithium disilicate and zirconia reinforced lithium silicate were used; this may have contributed to differences in retention. The ceramic composition and intaglio surfaces are specific
for each ceramic; thus, conclusions drawn for one ceramic type may not apply to others.
In addition, in the previously mentioned studies,43, 56, 57 the axial walls were used to calculate the surface area, and the occlusal surface was excluded because of different surface
roughness. However, in this study, the surface area of the occlusal and axial walls was
measured as surface area because they were both prepared with a medium-grit diamond
rotary cutting instrument and had similar roughness. Therefore, the higher angle of total
occlusal convergence, different ceramics, and a larger surface area may have contributed
to the lower crown retention values observed in the present study. Furthermore, the physical properties of the cement may influence the retentive qualities.
In the present study, although there was no difference in surface area and axial wall
height of the preparations between tested groups, standard deviations were rather high for
crown retention. Previous studies56-58also show high standard deviation, which may be
due to the variability inherent with using natural teeth. Studies based on tooth structure
show that dentinal bonding may be influenced by dentinal depth preparation, tubule orientation, and age of tooth and proximity of dentin to pulp tissue. It is very important to
control dentin depth because the adhesive strength is 1.6 to 10.7 times greater in the superficial layer than in the deep layer61 Other important factors which influence the dentin
41
bonding is tooth age, location and sclerosis. The factors affecting the bonding of resin to
tooth structure cannot be completely controlled due to use of natural teeth. In order to
control these variables, an in-vitro prefabricated artificial tooth can be used.
In this study, data shows failure mode of
Category 1.
27.27%- Cement mainly on prepared tooth
Category 2.
10%- Cement on both crown and tooth
Category 3.
20.9%- Cement mainly on crown (over 75%)
Category 4.
30.90%-Fracture of tooth root without crown separation
Category 5.
10%- Fracture of Crown
The 10% of crown fracture (category 5) was noticed only with Celtra. Some of the Celtra
coping fractured during testing, as shown in Figure 29 and to evaluate the cause of fracture SEM of Celtra disc was performed, SEM pictures are presented in Table 10..
Figure 29: Fractured Celtra crown during testing
42
Table 9: SEM of Celtra
HF
Polished
Fired
3000
No
Yes
Yes
No
Yes
Yes
Unfired
30,000
3000
Back
Scattered
No
No
Back
Scattered
43
30,000
LIMITATIONS
1. This in–vitro study may not completely simulate in-vivo performance for example
crowns were luted at room temperature.
2. All the cements were allowed to self-cure, studies have shown that light activation
of the resin cements improved their shear bond strengths. 62
3. Fracture of 34 teeth and fracture of 11 crowns out 110 also might have some confounding effect on the result.
44
CONCLUSION
Within the limits of this study, when e.max is used for restoration of single tooth dual
cure resin cement shows a good retention strength. When luting e.max with RMGI, hydrofluoric etching is not necessary as it lowers the retention.
When Celtra is bonded with the Experimental resin cement, etching the intaglio with
5%HF for 20 secs and application of Silane seems to improve the bond strength, while
the use of Prime & Bond Elect is optional. However, when Celtra is luted with RMGI,
etching the intaglio with 5% HF is advisable to improve its retention
45
FUTURE DIRECTIONS
1. Polishing or firing the Celtra copings.
2. Incorporating fatigue testing.
46
REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Donovan TE. Factors essential for successful all-ceramic restorations. J Am Dent
Assoc 2008;139 Suppl:14s-18s.
Devigus A. [All-ceramic restorations in the esthetic zone--the problem of choice].
Schweiz Monatsschr Zahnmed 2011;121(6):549-59.
Uy JN, Lian JN, Nicholls JI, Tan KB. Load-fatigue performance of gold crowns
luted with resin cements. J Prosthet Dent 2006;95(4):315-22.
Thyssen JP, Menne T, Moller P, Jellesen MS, Johansen JD. A cobalt spot test was
useful in the diagnostic work-up of a cobalt allergic patient suffering from oral
hypersensitivity to cobalt. J Am Acad Dermatol. United States; 2011. p. 659-60.
Song H, Yin W, Ma Q. Allergic palmoplantar pustulosis caused by cobalt in cast
dental crowns: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
2011;111(6):e8-10.
Barao VA, Gennari-Filho H, Goiato MC, dos Santos DM, Pesqueira AA. Factors
to achieve aesthetics in all-ceramic restorations. J Craniofac Surg
2010;21(6):2007-12.
Conrad HJ, Seong WJ, Pesun IJ. Current ceramic materials and systems with
clinical recommendations: a systematic review. J Prosthet Dent 2007;98(5):389404.
Bidra AS, Chapokas AR. Treatment planning challenges in the maxillary anterior
region consequent to severe loss of buccal bone. J Esthet Restor Dent
2011;23(6):354-60.
Fasbinder DJ, Dennison JB, Heys D, Neiva G. A clinical evaluation of chairside
lithium disilicate CAD/CAM crowns: a two-year report. J Am Dent Assoc
2010;141 Suppl 2:10s-4s.
Mormann WH. The evolution of the CEREC system. J Am Dent Assoc 2006;137
Suppl:7s-13s.
Pieper R. Digital impressions--easier than ever. Int J Comput Dent 2009;12(1):4752.
Henkel GL. A comparison of fixed prostheses generated from conventional vs
digitally scanned dental impressions. Compend Contin Educ Dent
2007;28(8):422-4, 26-8, 30-1.
Shiraishi T, Wood DJ, Shinozaki N, van Noort R. Optical properties of base
dentin ceramics for all-ceramic restorations. Dent Mater 2011;27(2):165-72.
Syrek A, Reich G, Ranftl D, et al. Clinical evaluation of all-ceramic crowns
fabricated from intraoral digital impressions based on the principle of active
wavefront sampling. J Dent 2010;38(7):553-9.
Beuer F, Schweiger J, Edelhoff D. Digital dentistry: an overview of recent
developments for CAD/CAM generated restorations. Br Dent J 2008;204(9):50511.
Kelly JR. Dental ceramics: current thinking and trends. Dent Clin North Am
2004;48(2):viii, 513-30.
47
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
Edelhoff D, Ozcan M. To what extent does the longevity of fixed dental
prostheses depend on the function of the cement? Working Group 4 materials:
cementation. Clin Oral Implants Res 2007;18 Suppl 3:193-204.
Suttor D, Bunke K, Hoescheler S, Hauptmann H, Hertlein G. LAVA--the system
for all-ceramic ZrO2 crown and bridge frameworks. Int J Comput Dent
2001;4(3):195-206.
Suttor D. Lava zirconia crowns and bridges. Int J Comput Dent 2004;7(1):67-76.
Burke FJ, Fleming GJ, Nathanson D, Marquis PM. Are adhesive technologies
needed to support ceramics? An assessment of the current evidence. J Adhes Dent
2002;4(1):7-22.
Manso AP, Silva NR, Bonfante EA, et al. Cements and adhesives for all-ceramic
restorations. Dent Clin North Am 2011;55(2):311-32, ix.
Wegner SM, Kern M. Long-term resin bond strength to zirconia ceramic. J Adhes
Dent 2000;2(2):139-47.
Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. J
Prosthet Dent 2003;89(3):268-74.
Atsu SS, Kilicarslan MA, Kucukesmen HC, Aka PS. Effect of zirconium-oxide
ceramic surface treatments on the bond strength to adhesive resin. J Prosthet Dent
2006;95(6):430-6.
Inokoshi M, De Munck J, Minakuchi S, Van Meerbeek B. Meta-analysis of
bonding effectiveness to zirconia ceramics. J Dent Res 2014;93(4):329-34.
Feilzer AJ, De Gee AJ, Davidson CL. Setting stress in composite resin in relation
to configuration of the restoration. J Dent Res 1987;66(11):1636-9.
Nikolaenko SA, Lohbauer U, Roggendorf M, et al. Influence of c-factor and
layering technique on microtensile bond strength to dentin. Dent Mater
2004;20(6):579-85.
Heintze SD. Crown pull-off test (crown retention test) to evaluate the bonding
effectiveness of luting agents. Dent Mater 2010;26(3):193-206.
Zidan O, Ferguson GC. The retention of complete crowns prepared with three
different tapers and luted with four different cements. J Prosthet Dent
2003;89(6):565-71.
Gundler A, Lockowandt P, Erhardson S. Crown retention and cyclic loading (in
vitro). Scand J Dent Res 1993;101(4):252-6.
Wiskott HW, Nicholls JI, Belser UC. The relationship between abutment taper
and resistance of cemented crowns to dynamic loading. Int J Prosthodont
1996;9(2):117-39.
Cameron SM, Morris WJ, Keesee SM, Barsky TB, Parker MH. The effect of
preparation taper on the retention of cemented cast crowns under lateral fatigue
loading. J Prosthet Dent 2006;95(6):456-61.
Ali AO, Kelly JR, Zandparsa R. The influence of different convergence angles
and resin cements on the retention of zirconia copings. J Prosthodont
2012;21(8):614-21.
Dodge WW, Weed RM, Baez RJ, Buchanan RN. The effect of convergence angle
on retention and resistance form. Quintessence Int 1985;16(3):191-4.
48
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
Madina MM, Ozcan M, Badawi MF. Effect of surface conditioning and taper
angle on the retention of IPS e.max Press crowns. J Prosthodont 2010;19(3):2004.
Ayad MF, Rosenstiel SF, Salama M. Influence of tooth surface roughness and
type of cement on retention of complete cast crowns. J Prosthet Dent
1997;77(2):116-21.
Ayad MF, Rosenstiel SF, Woelfel JB. The effect of recementation on crown
retention. Int J Prosthodont 1998;11(2):177-82.
Yim NH, Rueggeberg FA, Caughman WF, Gardner FM, Pashley DH. Effect of
dentin desensitizers and cementing agents on retention of full crowns using
standardized crown preparations. J Prosthet Dent 2000;83(4):459-65.
Mitchell CA, Abbariki M, Orr JF. The influence of luting cement on the
probabilities of survival and modes of failure of cast full-coverage crowns. Dent
Mater 2000;16(3):198-206.
Wolfart S, Linnemann J, Kern M. Crown retention with use of different sealing
systems on prepared dentine. J Oral Rehabil 2003;30(11):1053-61.
Johnson GH, Lepe X, Bales DJ. Crown retention with use of a 5% glutaraldehyde
sealer on prepared dentin. J Prosthet Dent 1998;79(6):671-6.
Johnson GH, Hazelton LR, Bales DJ, Lepe X. The effect of a resin-based sealer
on crown retention for three types of cement. J Prosthet Dent 2004;91(5):428-35.
Palacios RP, Johnson GH, Phillips KM, Raigrodski AJ. Retention of zirconium
oxide ceramic crowns with three types of cement. J Prosthet Dent
2006;96(2):104-14.
Soeno K, Taira Y, Jimbo R, Sawase T. Surface treatment with ascorbic acid and
ferric chloride improves the micro-tensile bond strength of 4-META/MMA-TBB
resin to dentin. J Dent 2008;36(11):940-4.
Chang JC, Hurst TL, Hart DA, Estey AW. 4-META use in dentistry: a literature
review. J Prosthet Dent 2002;87(2):216-24.
Stawarczyk B, Basler T, Ender A, et al. Effect of surface conditioning with
airborne-particle abrasion on the tensile strength of polymeric CAD/CAM crowns
luted with self-adhesive and conventional resin cements. J Prosthet Dent
2012;107(2):94-101.
Cano-Batalla J, Soliva-Garriga J, Campillo-Funollet M, Munoz-Viveros CA,
Giner-Tarrida L. Influence of abutment height and surface roughness on in vitro
retention of three luting agents. Int J Oral Maxillofac Implants 2012;27(1):36-41.
Rosenstiel SF, Land MF, Crispin BJ. Dental luting agents: A review of the current
literature. J Prosthet Dent 1998;80(3):280-301.
Kramer N, Lohbauer U, Frankenberger R. Adhesive luting of indirect restorations.
Am J Dent 2000;13(Spec No):60D-76D.
Hill EE. Dental cements for definitive luting: a review and practical clinical
considerations. Dent Clin North Am 2007;51(3):643-58, vi.
Pace LL, Hummel SK, Marker VA, Bolouri A. Comparison of the flexural
strength of five adhesive resin cements. J Prosthodont 2007;16(1):18-24.
Lee IB, An W, Chang J, Um CM. Influence of ceramic thickness and curing mode
on the polymerization shrinkage kinetics of dual-cured resin cements. Dent Mater
2008;24(8):1141-7.
49
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
Cattani-Lorente MA, Dupuis V, Payan J, Moya F, Meyer JM. Effect of water on
the physical properties of resin-modified glass ionomer cements. Dent Mater
1999;15(1):71-8.
Cury AH, Goracci C, de Lima Navarro MF, et al. Effect of hygroscopic expansion
on the push-out resistance of glass ionomer-based cements used for the luting of
glass fiber posts. J Endod 2006;32(6):537-40.
Karimipour-Saryazdi M, Sadid-Zadeh R, Givan D, et al. Influence of surface
treatment of yttrium-stabilized tetragonal zirconium oxides and cement type on
crown retention after artificial aging. J Prosthet Dent 2014;111(5):395-403.
Ernst CP, Cohnen U, Stender E, Willershausen B. In vitro retentive strength of
zirconium oxide ceramic crowns using different luting agents. J Prosthet Dent
2005;93(6):551-8.
Ernst CP, Aksoy E, Stender E, Willershausen B. Influence of different luting
concepts on long term retentive strength of zirconia crowns. Am J Dent
2009;22(2):122-8.
Shahin R, Kern M. Effect of air-abrasion on the retention of zirconia ceramic
crowns luted with different cements before and after artificial aging. Dent Mater
2010;26(9):922-8.
Rafeek RN, Marchan SM, Seymour KG, Zou LF, Samarawickrama DY.
Abutment taper of full cast crown preparations by dental students in the UWI
School of Dentistry. Eur J Prosthodont Restor Dent 2006;14(2):63-6.
Jorgensen KD. The relationship between retention and convergence angle in
cemented veneer crowns. Acta Odontol Scand 1955;13(1):35-40.
Nakamichi I, Iwaku M, Fusayama T. Bovine teeth as possible substitutes in the
adhesion test. J Dent Res 1983;62(10):1076-81.
Aguiar TR, Di Francescantonio M, Arrais CA, et al. Influence of curing mode and
time on degree of conversion of one conventional and two self-adhesive resin
cements. Oper Dent 2010;35(3):295-9.
50
APPENDIX A
INSTIUTIONAL REVIEW BOARD APPROVAL
51
52