A COMPARATIVE STUDY TO EVALUATE THE EFFECTIVENESS
OF TWO DIFFERENT SURFACE TREATMENTS ON THE RETENTION OF
ZIRCONIUM COPINGS – AN IN VITRO STUDY
Dissertation submitted to
THE TAMILNADU Dr. M.G.R. MEDICAL UNIVERSITY
In partial fulfillment for the degree of
MASTER OF DENTAL SURGERY
BRANCH I
CERTIFICATE
This is to certify that this dissertation titled “A COMPARATIVE STUDY TO
EVALUATE THE EFFECTIVENESS OF TWO DIFFERENT SURFACE
TREATMENTS ON THE RETENTION OF ZIRCONIUM COPINGS” – AN IN VITRO STUDY” is a bonafide record of work done by Dr. B.DEEPAK KUMAR
under my guidance and to my satisfaction during his postgraduate study period of
2016-2019.
This dissertation is submitted to THE TAMILNADU Dr. M.G.R MEDICAL
UNIVERSITY, in partial fulfilment for the degree of MASTER OF DENTAL
SURGERY in PROSTHODONTICS INCLUDING CROWN AND BRIDGE AND
IMPLANTOLOGY. It has not been submitted (partially or fully) for the award of
any other degree or diploma.
Guide:
Dr.ANJANA KURIEN M.D.S., PROFESSOR,
DEPARTMENT OF PROSTHODONTICS INCLUDING CROWN AND BRIDGE AND
IMPLANTOLOGY. Dr.G.R.RAHUL M.D.S.,
PROFESSOR & HEAD OF THE DEPARTMENT DEPARTMENT OF PROSTHODONTICS INCLUDING CROWN AND BRIDGE AND
IMPLANTOLOGY.
Dr.V.PRABHAKAR M.D.S., PRINCIPAL,
SRI RAMAKRISHNA DENTAL COLLEGE AND HOSPITAL.
DECLARATION
TITLE OF DISSERTATION
A COMPARATIVE STUDY TO EVALUATE THE EFFECTIVENESS OF TWO DIFFERENT SURFACE
TREATMENTS ON THE RETENTION OF ZIRCONIUM COPINGS – AN IN VITRO STUDY
PLACE OF STUDY
SRI RAMAKRISHNA DENTAL COLLEGE AND HOSPITAL, COIMBATORE – 641006
DURATION OF THE COURSE 3 YEARS
HEAD OF THE DEPARTMENT Dr.G.R.RAHUL
NAME OF THE GUIDE DR. ANJANA KURIEN
I hereby declare that no part of the dissertation will be utilized for gaining financial
assistance/ any promotion without obtaining prior permission of the Principal, Sri
Ramakrishna Dental College and Hospital, Coimbatore. In addition, I declare that no part of
this work will be published either in print or in electronic media without the permission of the
guide who has been actively involved to dissertation. The author has the right to reserve for publish of work solely with the prior permission of the Principal, Sri Ramakrishna Dental
College and Hospital, Coimbatore.
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CERTIFICATE II
This is to certify that this dissertation work titled A COMPARATIVE STUDY TO
EVALUATE THE EFFECTIVENESS OF TWO DIFFERENT SURFACE
TREATMENTS ON THE RETENTION OF ZIRCONIUM COPINGS – AN IN VITRO
STUDY of the candidate Dr. DEEPAK KUMAR.B with registration Number
of 241611351 for the award of Masters of Dental Surgery in the branch of Prosthodontics
including Crown and Bridge and Implantology. I personally verified the urkund.com
website for the purpose of plagiarism Check. I found that the uploaded thesis file contains
from introduction to conclusion pages and result shows 0 percentage of plagiarism in the
dissertation.
Head of the Department :
Guide & Supervisor sign with Seal Dr.G.R.RAHUL M.D.S.,
PROFESSOR & HEAD OF THE DEPARTMENT DEPARTMENT OF PROSTHODONTICS INCLUDING CROWN AND BRIDGE AND
IMPLANTOLOGY.
Guide:
Dr.ANJANA KURIEN M.D.S., PROFESSOR,
DEPARTMENT OF PROSTHODONTICS INCLUDING CROWN AND BRIDGE AND
ACKNOWLEDGEMENT
My heartfelt thanks to Dr.Premila Suganthan for her suggestions and supporting me for
my study on hard tissue Lasers.
I owe my thanks and gratitude to Dr.G.R.Rahul , Head of the department.
I would also like to Thank Prof. Dr.V. Prabhakar, Principal, Sri Ramakrishna Dental
College for his guidance and support.
It is my privilege to thank, my teacher Dr.Anjana Kurien Professor, Department of
Prosthodontics. For always taking time, in supporting me, and providing
encouragement whenever needed.
My family members were a great support and encouraged me in my entire endeavour, I
CONTENTS
TITLE PAGE NO
1. INTRODUCTION 1
2. AIM AND OBJECTIVES 3
3. REVIEW OF LITERATURE 4
4. MATERIALS AND METHODS 11
5. RESULTS 38
6. DISCUSSION 46
7. SUMMARY & CONCLUSION 51
8. BIBLIOGRAPHY 53
1
INTRODUCTION
Success of an all ceramic restorations is highly dependent on achieving a bond
of the luting agent with the underlying tooth structure as well as with the restoration. Bonding is required for improving the retention, marginal adaptation, fracture resistance
and bond strength of restorations. It also increases surface energy, surface area for
bonding and wettability. During the fabrication or milling of the ceramic, sufficient
bond strength values are not generated, therefore it requires surface pre-treatment. Bond
strength can be improved by the presence of micromechanical retention, as the creation
of roughened ceramic surfaces may allow resin cement to penetrate and flow into such
micro pores, thereby creating a stronger micromechanical interlock.
There are several tests for assessment of bond strength of resin-based materials
to dental ceramics namely shear, tensile, and microtensile tests. These test methods are
based on the application of a load in order to generate stress at the adhesive joints until
failure occurs. There are various surface treatment methods namely grinding, abrasion with diamond rotary instruments, airborne particle abrasion, silicate coating, acid
etching, coupling with silane and combinations of any of these methods. Airborne
particle abrasion with aluminium oxide abrasive particles has been identified as an
effective means of achieving a stable, durable bond for Zirconia ceramics1,2.
Recently, due to advances in Laser techniques, some studies have suggested
application of Lasers such as Carbon dioxide(CO2), Erbium-Doped Yttrium Aluminium
Garnet Laser (Er:YAG) and Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) to bring about changes on Zirconia ceramics to improve their bond to tooth structures.
Some studies have shown that use of CO2 and Er:YAG Lasers improves the bond
2
Use of resin cements improves retention, fracture resistance and the marginal
adaptation of the restoration to the tooth structures. The resin cement contains MDP (10-methacryloyloxyidecyl-dihydrogenphosphate) which is filler that will chemically
react with Zirconium dioxide, promoting a water-resistant bond to densely sintered
Zirconia ceramic. It has been reported that use of adhesive resin cements containing
phosphate monomers may contribute to bonding with Zirconia restorations to tooth
structures6.
The aim of this present study was to evaluate and compare the effects of sand
blasting with alumina 110 µm and Er:YAG Lasers on the tensile bond strength of resin
3
AIM AND OBJECTIVES
AIM:
The aim of the study is to compare the effectiveness of two different surface treatments on the retention of Zirconia copings (NexxZr ,USA) using dual cure resin
cement (Panavia F 2.0 , Japan).
OBJECTIVES :
To determine the tensile strength of sand blasted Zirconia coping (Al2O3
-110µm).
To determine the tensile strength of Laser treated Zirconia coping (Er:YAG).
To compare the tensile strength of sand blasted Zirconia coping with Laser
treated Zirconia copings.
The first null hypothesis for the present study is the various types of surface
treatment does not increases the tensile bond strength of Zirconia to the tooth structure.
The second null hypothesis is the Er:YAG Laser does not have an effective
4
REVIEW OF LITERATURE:
The effect of dry and wet grinding and sandblasting with alumina (110µm) on
the microstructure, biaxial flexural strength and reliability of two yttria stabilized
tetragonal Zirconia (Y-TZP) ceramics was evaluated by Kosmac7 in 1999. He
concluded that sandblasting with alumina (110µm) gives more surface roughness when
compared to dry and wet grinding surface treatments.
Sandblasting is a commonly used surface treatment technique for dental crowns
to improve the adhesion of the mating parts of a restoration. Ravi Kiran Chintapalli8 in
2013 did a study on effect of different sandblasting conditions on the mechanical
properties of yttria stabilized tetragonal Zirconia(Y-TZP).The specimens were
sandblasted considering two different particle sizes(110,250 μm).He concluded that
Sandblasting with particles sizes equal or less than 110 μm and pressures less than 4bar
increase the bi-axial strength of the Zirconia ceramics
In a study did by Naichuan Su9 in 2015 to measure the short-term bond strength
between an indirect composite resin (ICR) and Zirconia ceramic after various
sandblasting processes. Zirconia bars sandblasted with different pressures of 0.1, 0.2,
0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds,and alumina powder sizes of 50 and 110 μm. The control group did not receive sandblasting.He concluded that
sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 μm had improve the bond strength of Zirconia ceramic.
In a study done by Mutlu Ozcana in 200310 he evaluated the effect of three
various surface conditioning methods on the bond strength of a Bis-GMA based luting
cement to 6 commercial dental ceramics. The specimens in each group were randomly
5
Airborne particle abrasion, (3) Tribochemical silica coating.The shear bond strength of
luting cement to ceramics was calculated in a universal testing machine (1 mm/min). He
concluded the tribochemical silica coating and air abrasion with alumina 110µm shows more bond strengths of the resin composite luting cement tested on the dental ceramics
after surface conditioning.
Gilberto Antonio Borges11 in 2003 assessed the surface topography of 6
different Zirconia ceramics after treatment with either hydrofluoric acid etching or
airborne aluminum oxide particle abrasion 50 µm. Each specimen was longitudinally
sectioned into 4 equal parts by a diamond disk. He concluded that Hydrofluoric acid
etching and airborne particle abrasion with 50- µm aluminum oxide increased the
irregularities on the surface of Zirconia ceramics.
The durability of bond strength between a resin cement and aluminous ceramic
submitted to three surface conditioning method(sandblasting,salinization,Tribochemical
silica coating) was evaiuated by Borges in 200312 with glass-infiltrated Zirconia–
alumina ceramics. Each specimen was fixated with cyanoacrylate gel. He stated that
silica coating groups showed higher bond strength values compared to the group air abraded with alumina (110µm) and the topographic patterns of the specimen surfaces
after three treatment methods appeared to be similar with sand particles.
The effect of three surface conditioning methods on the microtensile bond
strength of resin cement to a glass-infiltrated Zirconia and alumina-based core ceramic
was evaluated by Regina Amaral in 200613. The specimens were polished and alligned
to one of the following three treatment conditions (1) Airborne particle abrasion with
6
particles (CoJet, 3M ESPE) C silanization. The ceramic-composite blocks were
cemented with the resin cement (Panavia F). She concluded that Silica coating with
silanization using 110 mm SiO2 or 30 mm SiO2 particles increased the bond strength of the resin cement to the Zirconia-based ceramic significantly compared to airborne
particle abrasion with alumina .
Ana Maria Spohr in 2008 11 evaluated the effect of various surface treatments
on bond strength between Ceram Zirconia ceramic and Panavia Fluoro Cement.
In-Ceram Zirconia blocks received 3 different surface treatments alumina sandblasting
(110µm) , alumina sandblasting Rocatec Plus silane; and combination of alumina
sandblasting , Nd:YAG Laser . Resin cement was applied and light-cured, followed by
the application of composite resin.. Microtensile bond strength (TBS) was recorded
using a universal testing machine at a cross-head speed of 0.5 mm/min. He concluded
that Nd:YAG Laser irradiation is an effective surface treatment for bonding between
In-Ceram Zirconia and Panavia Fluoro cement.
In a study done by Moustafa N. Aboushelib in 200814 evaluated the
microtensile bond strength of resin-to-Zirconia bond strength using selective infiltration etching and novel silane-based Zirconia primers using Zirconia discs (Procera Zirconia)
received selective infiltration etching surface treatment and bonded to the treated
surface using an MDP-containing resin-composite (Panavia F 2.0). The bilayered
specimens were cut into microbars and the microtensile bond strength (MTBS) was
evaluated. He concluded that selective infiltration etching surface treatment resulted in
a nano-retentive surface where shows more microtensile bond strength .
7
The influence of hydrofluoric acid-etched treatment on the surface topography
of the Zirconia veneering ceramic was evaluated by Yada Chaiyabutr in 200815, to test
the bond strength of Zirconia veneering ceramic to enamel, and to evaluate the flexural strength and the elemental composition of ceramic veneers. Ten specimens from each
group of materials were examined with a profilometer, and a sample of this group was
selected for quantitative evaluation using a scanning electron microscope
(SEM).Another 10 acid-etched specimens from each group of materials were treated
with silane prior to cementing with resin cement (Variolink II) on enamel surfaces.
These luted specimens were loaded to failure in a universal testing machine in the shear
mode with a crosshead speed of 0.05 mm/min. He concluded that Effective ceramic
interface management, such as acid etching and enamel bonding, is essential for
successful ceramic laminate veneer restorations. Not all Zirconia veneering ceramics
display the same quality of surface roughness after hydrofluoric acid etching and the
same bond strength to enamel when used as laminate veneer.
In a report by Jin-Ho Phark in 200917 evaluated the shear bond strength (SBS)
of composite resin cylinders to a modified Zirconia surface using different luting
techniques after thermal cycling.. Three different adhesive luting cements (Panavia
F2.0, RelyX ARC, RelyX Unicem) in combination with and without airborne-particle
abrasion (50-μm and 110-μm Alumina) were used. Shear bond strength was tested in
a universal testing machine. He concluded that Shear bond strength to the modified
Zirconia surface is higher than to airborne-particle-abraded, machined Zirconia.
The effects of CO2 Laser and conventional surface treatments on surface
roughness and shear bond strengths of glass-infiltrated alumina-ceramics to dentin was
8
were untreated (control group), sandblasted (alumina 110µm), airborne particle
abraded, etched with 9.6% hydrofluoric acid or irradiated with CO2 Laser. Scanning
electron microscope was used at 1000 magnification for qualitative examination. Shear bond strength (MPa) test was performed using a universal testing machine at a
crosshead speed of 1 mm/min. He concluded that Sandblasting(alumina 110µm) is an
effective surface treatment for roughening surfaces of In-Ceram Spinell.
In a article by Musa S¸amil Akyıl in 201119 evaluated the shear bond strength
of a resin cement to yttrium stabilized tetragonal Zirconia (Y-TZP) surfaces treated with
air abrasion (alumina 110µm), silica coating, CO2, Er:YAG, Nd:YAG Laser irradiation.
One hundred forty-one Y-TZP discs were assigned to nine groups: C,no treatment; AA,
air abrasion; CJ, silica coating; ER, Er:YAG Laser; ND, Nd:YAG Laser; CO2 Laser; air
abrasion Er:YAG Laser; air abrasion Nd:YAG Laser; air abrasion CO2 Laser. The
composite cylinders were fabricated. After the surface treatments, the specimens were
silanized and composite cylinders were cemented with the resin cement. The shear bond strength test was performed after specimens were stored in water for 24 hours .He
concluded that Er:YAG Laser was most effective irradiation when compared to air
abrasion (alumina 110µm) and silica coating.
Ahmed Attia in 201120 evaluated the influence of various surface treatment
airborne-particle abrasion (AA), silica-coating, (SC) (CoJet) and silica coating followed
by silane application (SCSI) (ESPE Sil) using composite and ceramic blocks. He
concluded that Silica coating followed by silane application together with adhesive
resin cement significantly increase the tensile bond strength.
9
was evaluated by Hakan Akın in 201221. They were cemented onto the dentin with
dual-cured resin cement (Variolink). The fractured specimens were examined under a
stereomicroscope to evaluate the fracture pattern.He concluded that Er:YAG and Nd:YAG Laser treatment increased the bond strength of Zirconia compared to
sandbasting and CO2 Laser treatment.
In an article Cagri ural in 2010 22 compare the effects of various surface
treatments and Laser irradiation on the shear bond strength of resin cement to
Zirconia-based ceramic. 40 Zirconia core specimens were made and divided as Group C is no
treatment applied (control); Group SB is considered as bonding surfaces of ceramic
disks were airborne particle-abraded with 110um alumina oxide particles; Group HF
refers bonding surfaces of ceramic disks were etched with 9.6% hydrofluoric acid; and
Group L states bonding surfaces of ceramic disks were irradiated by a CO2 Laser. A
total of 40 composite resin disks were cemented with an adhesive resin cement to the
specimen surfaces. He concluded that CO2 Laser etching is an effective method for conditioning Zirconia surfaces, enhancing micromechanical retention and improves the
bond strength of resin cement on Zirconia ceramic.
The durability of the bond of conventional dual-cured resin cements to Procera
alumina and zirconium oxide ceramics after surface treatment with air abrasion(alumina
110µm) and erbium Laser was evaluated by Richard M. Foxton in 201123. The surface
of each specimen was then primed and bonded with one of two dual-cured resin
cements and a microshear bond strength test was performed at a crosshead speed of 1 mm/min.He concluded that Er:YAG Laser treatment of the Zirconia surface improves
10
Hakan Akin in 201124 investigated the effect of Er:YAG Laser irradiation on
shear bond strength and microleakage between resin cements and yttrium stabilized
tetragonal Zirconia (Y-TZP) ceramics. Eighty disc specimens of Y-TZP ceramics were prepared. He concluded that Er:YAG Laser surface treatment of Y-TZP ceramic
resulted in higher mean tensile bond strengths than those of control specimens.
Moreover, Er:YAG Laser surface treatments were found effective for decreasing
microleakage in the adhesive-ceramic interface.
A study did by Saadet Saglam Atsu in 200629 stated the effects of
airborne-particle abrasion, silanization, tribochemical silica coating, and a combination of
bonding/silane coupling agent surface treatment methods on the bond strength of
zirconium-oxide ceramic to a resin luting agent. The composite resin cylinders were
bonded to the treated ceramic surfaces using an adhesive phosphate monomer–
containing resin luting agent (Panavia F). He concluded that Tribochemical silica
coating (CoJet System) and the application of an MDP–containing bonding/silane coupling agent mixture increased the shear bond strength between zirconium-oxide
ceramic and resin luting agent (Panavia F).
The effect of passive or active phosphoric acid (PA) application after
hydrofluoric acid (HA) treatment on the micro shear bond strength of lithium disilicate
was evaluated by Tatiana Cardona Giraldo in 201626. He concluded that the active
application of 37% PA after 9.6% HA application increased the microshear bond
11
MATERIALS AND METHODS
The study compares the effectiveness of two different surface treated (sandblasting and Laser surface treatment) Zirconia copings. The materials and methods used in this investigation are sequentially described in this section.
[image:18.596.96.546.189.491.2]1.Materials : TABLE-1
S.NO
PROCEDURE MATERIALS
USED
BRAND,MANUFACTURER
1 Fabrication of Zirconia coping
Zirconia block Contrast spray
NexxZr,USA Ferrochem ,India 2 Fabrication of
stainless steel die Stainless steel SS blocks,India 3 Cementation Dual cure adhesive
resin cement Panavia F 2.0, Japan 4 Sandblasting Aluminium oxide
110µm
Garreco,USA
5 Laser surface treatment
12
[image:19.596.94.541.73.791.2]2.ARMAMENTARIUM: TABLE-2
S.NO PROCEDURE MATERIALS
USED
BRAND & MANUFACTURER
1
Fabrication of stainless steel die
Personal computer Lathe
Vertical milling machine
HCL
Chetak ,India
Esteam ,Taiwan 2 Scanning of the
metal dies
Personal computer and windows 10 software
EXO-CAD v8 software 3D scanner
Samsung, EXOCAD Darmstadt ,Germany.
Shining DS-X,Germany.
3 Fabrication of Zirconia copings
Milling machine
Milling burs
imes-icore® GmbH,250i-dry , Eiterfeld,Germany . imes-icore axis milling burs (size-0.6mm,0.8mm,0.12mm)
4 Sintering Burnout furnace Kejia Furnace Co., Ltd,China
5 Cementation Customized jig SS blocks, India
6 Humidification Humidifier Bioline,India
7 Customized testing zig
Stainless steel block SS blocks,India
8 Testing of Specimen
Universal testing Machine
Zwick/Roell, Leominster, UK
13
3.STUDY DESIGN:
GROUP B
Fabrication of a standardized stainless steel metal die simulating a prepared molar from vertical machining center (vmc) milling
GROUP C
Cementation of Zirconia copings with the respective dies under loading pressure using PANAVIA F 2.0 (dual cure resin cement)
0
Measurement of microtensile bond strength using universal testing machine
RESULTS
STATISTICAL ANALYSIS
Fabrication of Zirconia coping for the metal die using CAD-CAM (24 samples)
GROUP A
Fabrication of Zirconia crowns with no surface treatments(8 samples – A1toA8)
Fabrication of Zirconia crowns with sandblasting by
alumina.(8samples- B1to B8)
14
4. METHODOLOGY:
1. Fabrication of stainless steel Die 2. Fabrication of Zirconia Copings
3. Grouping
Group A – No surface treatment (control Group)
Group B – sandblasting by alumina
Group C – Laser surface treatment
4. Cementation of Zirconia coping
5. Testing of the Specimens
6. Statistical Analysis
15
1.Fabrication of stainless steel die:
A standardized stainless steel die simulating a prepared molar crown was milled
from 25 mm square block of stainless steel. The die was milled with the following
dimension with a rectangular base and a cylindrical substructure.
1. Occluso-gingival height - 5.5 mm
2. Taper - 5°
3. Minor diameter - 9mm
4. Major diameter - 10 mm
5.Chamfer finish line - 0.4 mm
6. Base height - 5 mm
7. Base diameter - 11 mm
8. Substructure height - 8 mm
9. Substructure length - 20 mm
16
2.Fabrication of the specimens:
Twenty four stainless steel dies were designed initially using an Auto CAD
software according to the specified dimensions. These designs were projected as 3D
models and transferred to SolidWorks software that converted these designs into a
CAM software that could be accepted by the Esteam Vertical Machining Centre-Model
S33 (Esteam Milling Machine Co Ltd, Taiwan). By using this machinable datas the
proposed design was milled in 25mm square block in the vertical milling machine.
3.Fabrication of Zirconia copings
a. Designing of the Zirconia copings
A single metal die was used for scanning. The metal die was sprayed with the
contrast spray. The die was then placed in the 3D scanner(shining DS-X ) for scanning.
First 2D image was formed which was then converted to 3D image by the software .The software used for designing was EXOCAD Software. The 3D image was used for
designing and fabricating the Zirconia copings. The designing was done by the lab
professional. The designed image was saved in STL (StereoLithiography) format.
b. Milling of the Zirconia copings
The desired Zirconia copings were milled by using milling burs
(0.6mm,0.8mm,0.12mm) in the NeXXZr Zirconia blank (98.2mm×14 mm). Each blank
yielded 22 samples of Zirconia copings for the desired dimension. A new blank was placed in the imes-icore (5X) machine at the beginning of the milling. The time taken to
17
c. Sintering of the FPD copings
After the Zirconia copings were milled, they were placed in kejiu furnace
machine for 8 hours at a temperature of 14500c for sintering (According to the manufacturer’s recommendation).
4.Sandblasting by Alumina (Group B samples):
Each sample is Sandblasted (Ideal Blaster, Kingston) with aluminum oxide with
particle (110-μm) .The applied pressure was 2.5 psi at 10 mm distance from the inner
surface of copings for 10s. They were then ultrasonically cleaned in ethanol solution for
20 mins and air-dried.
5.Laser surface treatment(Group C samples):
The internal surfaces of Zirconia copings were coated with graphite powder to
increase Laser energy absorption and irradiated with Er:YAG Laser (Biolase
18
TABLE - 3
Wavelength 2780nm
pulse duration 60µs
output power 2W
pulse repetition 10Hz
Energy density 200 J/cm2
Tip Size 900µm micro tip
Water :Air spray ratio 4:4
Angle of exposure Perpendicular
The operator under complete safety steps for Laser with Laser eyewear ,Latex
gloves and face mask. The micro tip was adjusted manually at an approximate distance
of 0.5 mm, the entire inner surface of Zirconia coping (0.68 cm2), was irradiated at a
rate of 2 mm/s for 30 seconds using horizontal surface scanning mode.
6.Grouping:
The specimens were divided into 3 groups of 8 each:
Group A – No surface treatment (control group)
Group B – sandblasting by Alumina
[image:25.596.167.477.107.402.2]19
7.Cementation of Zirconia copings:
The surface treated Zirconia copings were cemented using resin modified glass ionomer cement (panavia F2.0) onto their corresponding stainless steel die according to the manufacturer’s instruction. The cement was applied to the internal surface of the
coping and slowly seated over the die. Cement was allowed to set for 5 mins under a
constant load of 5 kg using cementation jig. The excess flash was removed with an
explorer and cemented coping was removed from the jig.
8.Humidification:
All the samples were placed in a humidifier (Bioline, India) for 24 hours to simulate the oral conditions before subjected for tensile testing.
9.Testing samples under universal testing machine
All the samples were tested in the universal testing machine (Zwick/Roell,UK)
within 24 hours after placing in the humidifier. The cemented copings were oriented on
the universal testing machine using a customized jig.
In universal testing machine the tensile force were applied to Zirconia coping
with a cross head speed of 1mm/min, until the crown dislodged from the die.
Dislodgment of crowns due to cement failure was defined as a sharp fall in the force/movement curve of the testing machine or formation of any visible gap between
the crown and the metal die.The force recorded by the machine at the first peak of the
curve was recorded as the maximum amount of force required to dislodge the crown of
20
10. Statistical analysis
All the values were recorded as N/mm2.
Statistical analysis were performed in Statistical Package for Social Sciences
software (SPSS version 17, USA) using a personal computer. Data comparison was
done by applying specific statistical tests to find out the statistical significance of the
obtained results. The normality of the data was checked using Kolmogrov Smirnov test
and Shapiro-wilk’s test. Based on the normality, data between three groups and within
[Control ,sandblasting and Laser treatment] were compared using kruskal walli’s test
21
Fabrication of metal die :
[image:28.596.225.398.130.261.2]
Figure 1.Projection of designs as 3D models
[image:28.596.242.438.446.761.2]22
[image:29.596.219.429.413.660.2]Fabrication of Zirconia copings:
Figure 3..Milled stainless steel die
23
Figure 5. 3D image of the die in STL format
24
[image:31.596.221.412.70.341.2]
Figure 7. Final CAD desiging of Zirconia coping
25
Figure 9.. imes-icore milling unit
[image:32.596.194.431.500.674.2]26
[image:33.596.204.420.130.295.2]Figure 11. imes-icore milling of NexxZr blank
[image:33.596.221.404.445.684.2]27
Figure 13. Inner surface of the Zirconia coping after sintering
[image:34.596.188.435.517.729.2]Figure 14. outer surface of the Zirconia coping after sintering
28
Sandblasting by alumina:
[image:35.596.191.421.513.718.2]29
Figure 18.GROUP B-sandblasted Zirconia copings
[image:36.596.213.410.449.597.2]30
Laser surface treatment:
[image:37.596.226.413.431.782.2]
Figure 21.Graphite coated Zirconia copings
Figure 22 programmed Er;yag Biolase Laser
31
Figure 23.Laser irradiation on coping
32
Cementation of Zirconia coping:
[image:39.596.216.413.158.336.2]Figure 25.Armamentarium used for cementation
Figure 27 .Mixing cement for 20seconds
[image:39.596.332.529.433.627.2]33
[image:40.596.216.416.127.263.2]Figure 29.Application of constant load Fig
34
[image:41.596.217.417.155.291.2]Figure 30.Removal of excess cement
35
[image:42.596.160.470.72.264.2]36
Humidification :
[image:43.596.97.512.145.470.2]
37
Testing of the specimen:
[image:44.596.348.485.166.386.2]
38
RESULTS
The present study was designed with the objective of determining the tensile strength
of the zirconia copings under two different surface treatment using dual cure resin cement.
A total of 24 samples were used in this study. It is divided into 8 samples in each
group according to the surface treatments (sandblasted,Laser surface treated), Following
cementation of the fabricated zirconia copings over their respective stainless steel dies,they
were subjected to loading in a universal testing machine to apply a tensile force.
The testing machine would indicate dislodgement of crowns due to cement failure.
The force recorded by the machine at the first peak of the curve was recorded as the
maximum amount of force required to dislodge the crown of each specimen with a cross-head
speed of 1mm/min. A sharp fall in the force/ movement curve of this readings were noted in each load level for all the samples, further the mean of each sample was calculated and the
results were subjected to statistical analysis.
The test process involves placing the test specimen in the testing machine and slowly
extending it until it decemented. During this process, the elongation of the gauge section is
recorded against the applied force. The elongation measurement is used to calculate
the engineering strain, ε, using the following equation.
where ΔL is the change in gauge length, L0 is the initial gauge length, and L is
the final length. where F is the tensile force and A is the nominal cross-section of the specimen The force measurement is used to calculate the engineering stress, σ, using the
following equation.
39
TABLE – 4 INDIVIDUAL VALUES OF TESTED SAMPLES
TABLE- 5 COMPARISON BETWEEN THE MEAN TENSILE STRENGTH OF THREE GROUPS
Sample no
Group A P value Sample no Group B P value
Sample no P value
Group C
A1 157.9 0.001 B1 536.7 0.001 C1 0.001 741.3
A2 231.3 0.001 B2 674.2 0.003 C2 0.001 736.3
A3 139.9 0.002 B3 607.5 0.001 C3 0.002 870.2
A4 139.3 0.001 B4 581.3 0.002 C4 0.001 810.2
A5 225.5 0.001 B5 593.9 0.001 C5 0.001 796.8
A6 121.3 0.003 B6 623.3 0.001 C6 0.001 889.3
A7 189.6 0.001 B7 610.1 0.002 C7 0.003 746.8
A8 193.7 0.002 B8 593.2 0.001 C8 0.001 850.9
Mean 174.75 0.003 Mean 602.5 0.001 Mean 0.002 805.25
[image:46.596.68.533.476.712.2]40
STATISTICAL ANALYSIS
KRUSKAL WALLIS TEST:
The Data was quantitative in nature, and as the number of samples were less than 30,
Non parametric tests were used as the test of significance. Kruskal Walli’s test was selected
as it satisfied the parameters (Quantitative data, N<30). The mean that was computed for each group and the standard error and range determined through statistical analysis was
subjected to Kruskal Walli's test to identify whether the difference among the groups was
significant enough for a comparative study among different groups.
TABLE 6 - COMPARING GROUP A, GROUP B AND GROUP C, USING
KRUSKAL WALLIS TEST:
GROUP N MINIMUM MAXI MEAN STD.DEVIA P
VALUE
A
VALUE MEAN8
121
231
174.75
41.438
0.001
0.001
0.002
B
VALUE MEAN8
537
674
602.50
38.792
[image:47.596.68.515.403.718.2]41 .0000 100.0000 200.0000 300.0000 400.0000 500.0000 600.0000 700.0000 800.0000 900.0000
MEAN VALID N (LISTWISE)
MEAN VALID N (LISTWISE)
MEAN VALID N (LISTWISE)
1 2 3
A xi s Ti tl e
1 2 3
mean Valid N
(listwise) mean
Valid N
(listwise) mean
Valid N (listwise)
Descriptive Statistics 121.0000 537.0000 737.0000
Descriptive Statistics 231.0000 674.0000 890.0000
Descriptive Statistics 174.750000 602.500000 805.250000 Descriptive Statistics 41.4380000 38.7920000 60.6580000
Mean comparing the value of group A,B and C shows that the mean rank of group
A is 4.50 and group B 12.50 and Group C is 20.50. Sum of the rank is higher in Group C.
TABLE 7- MEAN DIFFERENCE AMONG A, B, C GROUP
P VALUE is .001 , obtained value is significant , P value < 0.05 is significant
MEAN
GROU
P
N
MEAN
RANK
A
8
4.50
B
8
12.50
[image:48.596.63.511.100.437.2]42
STATISTICAL INFERENCE:
From the table 7 ,since p value <0.001 ,it is inferred that there is highly significant
difference existing between three groups. This table shows Group-C Laser treated zirconia copings have more tensile strength when compared to other two groups.
POST-HOC ANALYSIS- MANN WHITNEY TEST:
Now that the Kruskal Walli’s test has revealed the statistical significance of the
comparison, Mann-Whitney test was done to compare the significance of difference between
individual groups.
TABLE 8 - COMPARING THE MEAN VALUE OF TWO GROUPS - GROUP A
AND GROUP B
MEAN
GROUP N MEAN
RANK
SUM OF
RANKS
P value
.001
A 8 4.50 36.00B 8 12.50 100.00
TOTAL 16
[image:49.596.83.503.347.492.2]43
.00 20.00 40.00 60.00 80.00 100.00 120.00
Mea n Ra nk Sum of Ra nks
MEAN VALUE OF GROUP A AND B
mean mean mean
Mean comparing the value of group A and B shows that the mean rank of group A is 4.50 and
group B is 12.50. Sum of the rank is higher in Group A (100.00).
TABLE 9-COMPARING THE MEAN VALUE OF GROUP B AND C
MEAN
GROUP N MEAN RANK SUM OF
RANKS
P value
.001
B 8 12.50 100.00C 8 20.50 177.00
TOTAL 16
P VALUE is .001 , obtained value is significant
44
Mean comparing the value of group B and C shows that the mean rank of group B is 12.50 and group C 20.50. Sum of the rank is higher in Group C (177.000)
TABLE 10- COMPARING THE MEAN VALUE OF GROUP A AND C
P VALUE is .001 , obtained value is significant
P value < 0.05 is significant
mean mean
mean
Mean Rank Sum of Ranks
12.50
100.00
20.50
177.00
mean mean mean
MEAN
GROUP N MEAN
RANK
SUM OF
RANKS
P value
.002
A 8 4.50 36.00C 8 20.50 177.00
45 .00
20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00
MEAN RANK SUM OF RANKS
mean mean mean
Mean comparing the value of group A and C shows that the mean rank of group A is
4.50 and group C 20.50.Sum of the rank is higher in Group C (177.00).
STATISTICAL INFERENCE:
From the table 8,9,10,since p value <0.001, it is inferred that there is highly significant difference existing between three groups. Table 8 shows Group-B sandblasted
zirconia copings have more tensile strength when compared to Group A no surface treated.
Table 9 shows moderate significant difference between group C Laser treated when
compared to group B sand blasted zirconia copings. Table 10 shows more significant
[image:52.596.110.470.95.315.2]51
SUMMARY
This in-vitro study evaluated the influence of surface treatments on the bond
strength of resin cements to a yttrium-stabilized tetragonal Zirconia (Y-TZP). Die
models were fabricated by CMC milling machine in a standard molar Zirconia
prepation ,this was further scanned and Zirconia copings were fabricated by CAD-CAM,totally twenty four Zirconia copings were assigned to 3 groups (n=8) according
to the surface treatment (none, air abrasion with Al2O3 particles (110µm), Er:YAG
Laser irradiation.
These samples were cemented with die models by using dual resin
cement(Panavia F2.0) according to manufacturer’s instructions. The samples were
placed in a humidifier for 24 hours to simulate the oral conditions. The samples were
tested in universal testing machine. The tensile force were applied to Zirconia coping
with a cross head speed of 1mm/min, until the crown dislodged from the die.
Dislodgment of crowns due to cement failure was defined as a sharp fall in the force/movement curve of the testing machine or formation of any visible gap between
the crown and the metal die. All the values were recorded as N/mm2.
To know the statistical significance of the obtained results the normality of the
data was checked using Kolmogrov Smirnov test and Shapiro-wilk’s test between three
groups [Control,sandblasting and Laser treatment].
The results of this study revealed that Er;YAg Laser irradiated Zirconia copings
have higher bond strength with the dual cure resin cement (Panavia F2.0) when
52
CONCLUSION
The present study was undertaken to evaluate the tensile bond strength of two different
surface treatments on the retention of zirconium copings.
Within the limitations of the present study,
The tensile Bond strength of Er:YAG Laser surface treated showed greater bond
strength when compared to sandblasted (Al2O3 -110µm) Zirconia copings and
53
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GLOSSARY
LIST OF ABBREVIATIONS
CAD/CAM Computer Aided Design / Computer Aided Manufacturing (or Milling)
CNC Computerized Numerical Control
FDP Fixed Dental Prosthesis FPD Fixed Partial Denture GIC Glass Ionomer Cement PFM Porcelain Fused to Metal
MDP Methacryloyloxydecyl dihydrogen phosphate STL StereoLithography
Y-TZP Yttrium Tetragonal Zirconia Polycrystal