Bond strengths of porcelain laminate veneers to tooth surfac

[Glenn van As]

Neat study…….of course it was in enamel but my big big question.

What were the settings.

Glenn

[Anonymous]

Glenn,
With the hydrokinetics it doesn’t matter what settings you use 😉

Actually, I emailed the author and will let you know if I get a response.

Happy New Year!

[Glenn van As]

Oh darn it all ROn ……….now you tell me HK really does exist and I didnt include it in the text chapter…….

Oh man guess I better go revise it.

JUST KIDDING

Glenn

[Anonymous]

Glenn, Dr. Usumez was kind enough to send the whole study.

Bond strengths of porcelain laminate veneers to tooth surfaces prepared
with acid and Er,Cr:YSGG laser etching
Aslihan Usumez, DDS, PHD,a and Filiz Aykent, DDS, PHDb
Faculty of Dentistry, Selcuk University, Konya, Turkey
Statement of problem. The erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) hydrokinetic
laser system has been successful in the ablation of dental tissues. It has been reported that this system is also
useful for preparing tooth surfaces for adhesion, but results to date have been controversial.
Purpose. This in vitro study evaluated the bond strengths of porcelain laminate veneers to tooth surfaces after
etching with acid and Er,Cr:YSGG laser conditioning.
Material and method. Forty extracted caries- and restoration-free human maxillary central incisors were used.
The teeth were sectioned 2 mm below the cementoenamel junction. The crowns were embedded in autopolymerizing
acrylic resin with the labial surfaces facing up. The labial surfaces were prepared with .05 mm reduction
to receive porcelain veneers. The teeth were divided into 4 groups of 10 specimens. Thirty specimens received 1
of the following surface treatments before the bonding of IPS Empress 2 laminate veneers: (1) laser radiation
from an Er,Cr:YSGG laser unit; (2) 37% orthophosphoric acid; and (3) 10% maleic acid. Ten specimens received
no surface treatment and served as the control group. The veneers were bonded with dual-polymerizing resin,
Variolink II. One microtensile specimen from each of the cervical and incisal thirds measuring 1.2 1.2 mm was
prepared with a slow-speed diamond saw sectioning machine with a diamond-rim blade. These specimens were
attached to opposing arms of the microtensile testing device with cyanoacrylate adhesive and fractured under
tension at a crosshead speed of 1 mm/min, and the maximum load at fracture (Kg) was recorded. The data were
analyzed with a 2-way analysis of variance and Tukey HSD tests (.05).
Results. No statistically significant differences were found among the bond strengths of veneers bonded to
tooth surfaces etched with Er,Cr:YSGG laser (12.1 4.4 MPa), 37% orthophosphoric acid (13 6.5 MPa), and
10% maleic acid (10.6 5.6 MPa). The control group demonstrated the lowest bond strength values in all test
groups. Statistically significant differences were found between the bond strengths of cervical and incisal sections
(P.001).
Conclusion. In vitro microtensile bond strengths of porcelain laminate veneers bonded to tooth surfaces that
were laser-etched showed results similar to orthophosphoric acid or maleic acid etched tooth surfaces.
(J Prosthet Dent 2003;90:24-30.)
CLINICAL IMPLICATIONS
This in vitro study reported no difference in microtensile bond strengths of porcelain veneers
bonded to tooth surfaces that were etched with an Er,Cr:YSGG laser, 37% orthophosphoric acid,
or 10% maleic acid.
Patient demand for the treatment of unesthetic anterior
teeth has grown. For many years the most predictable
and durable esthetic correction of anterior teeth has
been achieved by the preparation of complete crowns.1
However, this approach is undoubtedly the most invasive
with the removal of substantial amounts of sound
tooth substance with possible adverse effects on adjacent
pulp and periodontal tissues.2,3
Calamia4 described the clinical and laboratory procedures
for bonding porcelain laminate veneers to acid
etched enamel. The popularity of porcelain laminate veneers
has increased since their introduction because
tooth preparation is conservative and the restorations
are esthetic.5 However, an in vitro study has described
some disadvantages such as marginal adaptation and related
bonding problems.6
Traditionally, etching the enamel surface with orthophosphoric
acid, a concept first proposed by Buonocore,
7 has been commonly used to increase the bond
strength between the composite and enamel. The technique
of etching with orthophosphoric acid is used to create
an irregular surface of enamel. This allows an increase in
the prepared surface area available for the retention of the
composite and an improvement in the marginal adaptation
of laminate veneers.8 The retentive characteristics of acidconditioned
enamel surfaces depend on the type of acid,
etching time, and chemical composition of enamel.9
aAssistant Professor, Department of Prosthodontics.
bAssociate Professor, Department of Prosthodontics.
24 THE JOURNAL OF PROSTHETIC DENTISTRY VOLUME 90 NUMBER 1
Three types of etching patterns have been described
by Silverstone et al10 after exposure of the enamel prisms
to etching solutions: type I, preferential removal of
prism core material, leaving the periphery intact; type II,
preferential removal of periphery core material, leaving
the prism core relatively unaffected; and type III, a more
random etching pattern in which adjacent areas of the
tooth surface correspond to types I and II, mixed with
regions in which the pattern could not be related to
prism structure. Morphologic information obtained by
scanning electron microscopy indicated that the surface
structure resulting from etching with 35% orthophosphoric
acid and 10% maleic acid is similar.11,12
Laser devices have been used in dentistry for soft
tissue surgery, root end sealing and sterilization, and for
altering enamel and dentin surfaces to increase resistance
to decay or to facilitate the bonding of composites.13,14
Laser etching may be an alternative to acid etching of
enamel and dentin. Laser etching is painless and does
not involve either vibration or heat, making this treatment
attractive.15 Furthermore, laser etching of enamel
or dentin has been reported to yield an anfractuous surface
(fractured and uneven) and open dentin tubules,
both apparently ideal for adhesion.15 The surface produced
by laser etching is also acid-resistant because laser
radiation of dental hard tissues modifies the calcium-tophosphorus
ratio, reduces the carbonate-to-phosphate
ratio, and leads to the formation of more stable and less
acid-soluble compounds, thus reducing susceptibility to
acid attack and caries.16
The ability of erbium:yttrium aluminum garnet (Er:
YAG) lasers to cut dental biocalcified tissue effectively
has been demonstrated.15 Furthermore, the cutting ef-
ficacy is improved when the tooth surfaces are flooded
with a water layer.15,17,18 The Er,Cr:YSGG pulsed-wave
laser, when used with an air-water spray, has been shown
to cut enamel, dentin, cementum, and bone efficiently
and cleanly.19,20 The Er,Cr:YSGG laser produces microexplosions
during tissue ablation, resulting in macroscopic
and microscopic irregularities.21 The Er,Cr:
YSGG laser initially causes vaporization of water and
other hydrated organic components of the tissue.21 On
vaporization, the internal pressure builds within the tissue
until the explosive destruction of inorganic substance
occurs before the melting point is reached.21
The quality of the bond obtained by laser etching of
enamel relates to the energy densities of the device.22
With low energy densities, the surface is largely unaffected
by laser pulses and retention is poor. At intermediate
exposures surface roughening occurs.22 At high
energy densities, the enamel is fused and this thin layer
of fused enamel becomes the weakest link in the chain of
adhesion.22
Laser-induced physical changes include melting and
recrystallization with the formation of numerous pores
and small, bubble-like inclusions. These profiles have
been shown by some studies in CO2 laser23 and Nd:
YAG laser.24,25 In contrast, no melting or recrystallization
was observed with Er,Cr:YSGG hydrokinetic system.
19,26
The purpose of this study was to determine the microtensile
bond strengths of porcelain laminate veneers
to acid-etched and Er,Cr:YSGG laser treated enamel,
with an unetched group serving as the control. The
enamel morphologic structure after laser etching and
acid etching was also investigated with scanning electron
microscopy (SEM). The hypothesis tested was that the
microtensile bond strength obtained after Er,Cr:YSGG
laser etching of enamel is similar to that obtained after
acid etching.
MATERIAL AND METHODS
Forty extracted human maxillary central incisors with
10 mm anatomic crown length and 8 mm mesiodistal
width were selected. Each tooth was free of dental caries
and restoration. The teeth were cleaned and stored in
saline solution at room temperature immediately after
extraction.
The teeth were sectioned 2 mm below the cementoenamel
junction with a slow-speed diamond saw sectioning
machine (Isomet; Buehler Ltd, Lake Bluff, Ill), and
the crowns were embedded in autopolymerizing acrylic
resin (Meliodent; Bayer Dental Ltd, Newbury, UK)
with the labial surfaces facing up.
Tooth preparation
The facial surfaces of the teeth were prepared to accommodate
veneers of equal thickness. A 0.5-mm facial
reduction was performed with a chamfered cervical finish
line and incisal bevel preparation. Self-limiting
depth-cutting disks of 0.5 mm (834-31-021; Gebr.
Brasseler, Lemgo, Germany) were used to define the
Fig. 1. Completed veneer preparation.
USUMEZ AND AYKENT THE JOURNAL OF PROSTHETIC DENTISTRY
JULY 2003 25
depth of the cuts, and then 1.4-mm chamfer diamond
burs (6844-314-014; Gebr. Brasseler) were selected to
refine the preparation. All tooth preparations were completed
without sharp line angles (Fig 1).
Impression making and master die fabrication
Impressions of the 40 prepared teeth were made with
polyvinylsiloxane impression material (Permagum; 3M
ESPE AG, Seefeld, Germany). The impressions were
poured with a vacuum-mixed polyurethane die material
(Alpha Die MF; Schu¨ltz-Dental GmbH, Rosbach, Germany)
according to the manufacturers’ instructions with
respect to water/power ratio and mixing time. Dies
were recovered from the impressions, and 2 layers of die
spacer (Cement Spacer; Kerr Dental, Orange, Calif)
were painted 0.5 mm short of the finish lines of the
preparations.
Ceramic veneer fabrication
The veneers were waxed (Yeti Dental produkte;
GmbH, Engen, Germany), sprued, and then pressed
after investment. All procedures were performed with
IPS Empress 2 materials (Ivoclar, Schaan, Liechtenstein),
following the manufacturer’s recommendations.
After divestment, the ceramic veneers were finished with
diamond burs (863-204-016; Gebr. Brasseler) and
glazed.
Surface treatment
The 40 prepared teeth were randomly assigned to 4
groups of 10 specimens (n 10). Each of 3 groups was
subjected to a different etching technique (Table I). Ten
specimens received no surface treatment and served as
the control group.
Laser treatment
An Er,Cr:YSGG hydrokinetic dental laser (Millennium;
Biolase Technology, Inc., San Clemente, Calif) was
used for laser etching. This hard- and soft-tissue laser
creates laser-energized, atomized water droplets that act
as cutting particles. Laser energy is delivered through a
fiberoptic system to a sapphire tip terminal 6 mm long
and 600 m in diameter, bathed in an adjustable air and
water vapor. It operates at a wavelength of 2.78 m;
pulse duration of 140 microseconds with a repetition
rate of 20 Hz. Average power output can be varied from
0 to 6W, depending on the tissue to be cut. The energy
and power densities were (5.6 J/cm2) and (111 W/cm2
at 2W), respectively, and were calculated by the manufacturer
of the laser unit for the used power adjustment.
The air and water spray of the hand-piece was adjusted
to the “30” scale of the laser unit. The beam was aligned
perpendicular to the enamel at 1 mm distance and was
moved in a sweeping fashion by hand during an exposure
period of 15 seconds over the entire area. The irradiated
specimen was dried with an oil-free air source for
15 seconds.
Bonding ceramic veneers
The ceramic veneers were treated with fluoridic acid
(Ceramic Etchant; Ceramco, Burlington, NJ) for 1
minute and neutralized (Ceramic Etchant Neutralizer;
Ceramco) in accordance with the manufacturer’s instructions.
Silane (Monobond S; Ivoclar) was first applied
with a brush to the ceramic veneers for 60 seconds,
and then a bonding agent (Heliobond; Ivoclar) was applied.
After the teeth were etched, primer (Syntac Primer;
Ivoclar) was applied to the tooth surface for 15 seconds,
adhesive (Syntac Adhesive; Ivoclar) for 10
seconds, and then a bonding agent (Heliobond; Ivoclar)
with a brush.
Cement (Variolink II; Vivadent, Ivoclar), comprising
a combination of 25% Variolink yellow base, 25% Variolink
white base, and 50% catalyst was hand-mixed following
the manufacturer’s directions, and applied to
both prepared teeth and the ceramic veneers. The ceramic
veneers were placed on the prepared teeth with
light finger pressure,27 and excess cement was removed
with an explorer. Photo polymerization was performed
with the light-polymerizing unit (Hilux 350; Express
Dental Products, Toronto, Canada) at 350 mW/cm2
(with a light tip to specimen distance of 0 mm) for 40
seconds for incisal, mesial, and distal surfaces.
Specimen preparation
After cementation, specimens were stored in distilled
water for 24 hours. Acrylic resin blocks were mounted in
a slow-speed diamond saw sectioning machine (Isomet)
with a diamond-rim blade.
Two saw cuts were made parallel to the long axis of
the tooth, and subsequently 4 saw cuts were made perpendicular
to the long axis. This produced 2 I-shaped
Table I. Materials used for surface conditioning
Material Used
Time of
etching Brand Manufacturer
37% orthophosphoric acid 15 s Bisco Bisco Inc, Schaumburg, Ill
10% maleic acid 15 s Scotchbond Multi-Purpose 3M, St. Paul, Minn
Er;Cr;YSGG hydrokinetic laser system 15 s Millennium Biolase Tech Inc, San Clemente, Calif
THE JOURNAL OF PROSTHETIC DENTISTRY USUMEZ AND AYKENT
26 VOLUME 90 NUMBER 1
specimens, 1 from the incisal portion, and the other
from the cervical (Fig. 2, A). The porcelain bonded to
the facial enamel surface was divided into an array of
1.2 1.2 5-mm beams (Fig. 2, B), with the top half
consisting of porcelain and the bonding agent, and the
bottom half consisting of enamel and dentin.28 Each
specimen was tested individually.29
Cyanoacrylate adhesive (Zapit; Dental Ventures of
America, Corona, Calif) was used to attach the microtensile
specimens to opposing arms of the microtensile
testing device (Harvard Apparatus Co. Inc., Dover,
Mass). The mounting adhesive was applied sparingly to
the edges of each specimen. The specimen was fractured
under tension at a crosshead speed of 1 mm/min, and
the maximum load at fracture (Kg) was recorded. Preparation
of all specimens and completion of the testing
were done by the same operator.
Fracture analysis
After the specimen was tested and removed from the
testing apparatus, the fracture sites were observed with a
stereomicroscope (SZTP; Olympus, Tokyo, Japan) at
original magnification 22 to identify the mode of failure.
The fractured surface was classified according to 1
of 3 types: (1) adhesive failure between the bonding
resin and the enamel/dentin; (2) cohesive failure in the
bonding resin; and (3) cohesive failure in the enamel/
dentin.
Statistical analysis
The ultimate stress (MPa) of the porcelain-enamel/
dentin bonds were calculated as follows:30
Stress
Failure Load (Kg)
Surface area (mm2) 9.8
The results of testing were entered into a spreadsheet
(Excel; Microsoft, Seattle, Wash) for calculation of descriptive
statistics. The obtained data were analyzed by
2-way analysis of variance and then Tukey HSD tests
(SPSS/PC, Vers.10.0; SPSS, Chicago, Ill) for pairwise
comparisons among groups (.05).
RESULTS
Microtensile bond strengths
The 2-way analysis of variance test indicated that tensile
bond strength was significantly affected by position
(cervical or incisal) (P.001) and treatment (acid or
laser) (P.001), and there was no significant interaction
between the 2 factors (P.05). Because there was no
significant interaction, all data in each group were
pooled. When the cervical and incisal data were pooled
to investigate the effect of a particular surface treatment
on bond strength, no statistically significant differences
were found between the bond strength values of veneers
bonded to 37% orthophosphoric acid (group B) and
Er,Cr:YSGG laser-etched tooth surfaces (group A).
Again, no statistically significant differences were found
between the bond strengths of veneers bonded to 37%
orthophosphoric (group B) and 10% maleic acid (group
C) etched tooth surfaces. Statistically significant differences
were found between the laser etched surfaces
(group A) and the control (group D) (P.05). There
were statistically significant differences between the orthophosphoric
acid etched surfaces (group B) and the
control (group D) (P.01). Additionally, no statistically
significant differences were observed between laser
etched and maleic acid etched tooth surfaces (Table II).
Mean bond strength values for different treatment
groups were calculated together with standard deviations
(Fig. 3). The mean bond strength of group B was
higher than the laser-treated group (group A) in the
incisal sections, but in the cervical sections group A was
higher. The control group (group D) demonstrated the
lowest bond strength values in all test groups (Table
III).
Fig. 2. A, Sections on tooth for specimen preparation (shaded
area represents section prepared from tooth specimen).
B, Schematic demonstration of specimen.
Table II. Microtensile bond strengths (MPa) statistical
comparison
Groups X SD
Tukey
grouping*
Group A (Laser) 12.1 4.4 A
Group B
(Orthophosphoric acid)
13.0 6.5 A
Group C (Maleic acid) 10.6 5.6 A
Group D (Control) 7.7 3.1 B
X, Mean; SD, standard deviation.
*Groups with different letters were statistically significantly different.
USUMEZ AND AYKENT THE JOURNAL OF PROSTHETIC DENTISTRY
JULY 2003 27
Fracture patterns
In the laser-treated group (group A), most failures
(17 of 20) were adhesive in nature at the bonding resin/
enamel interface, and 2 specimens showed cohesive failure
in the bonding resin. Only 1 specimen showed cohesive
failure within the enamel. In the group etched
with orthophosphoric acid (group B), most failures (19
of 20) were adhesive in nature at the bonding resin/
enamel interface. One specimen showed cohesive failure
within the enamel. The specimens in the group etched
with maleic acid (group C) and in the control group
(group D) showed adhesive fracture at the resin/enamel
interface.
Scanning electron microscopy
SEM photographs of 37% orthophosphoric acid, 10%
maleic acid, and Er,Cr:YSGG hydrokinetic laser-treated
enamel are shown in Figure 4. The enamel surface
etched with 2 acid solutions and a laser system showed
different results according to Silverstone’s10 etching
patterns. The 37% orthophosphoric acid removed the
periphery core material but left the prism core relatively
unaffected (type II), producing a very rough enamel
surface. The 10% maleic acid treatment resulted in preferential
removal of prism core material and left the periphery
intact (type I). Er,Cr:YSGG hydrokinetic lasertreated
enamel showed a more random etching pattern
in which adjacent areas of tooth surface correspond to
types I and II, mixed with regions where the pattern
could not be related to prism structure. There was no
recrystallization or melting observed.
DISCUSSION
The results obtained support the research hypothesis
of an expected similar adhesive force after laser treatment.
This result is in accordance with the study of
Usumez et al26 in which they compared these methods
for bonding orthodontic brackets to enamel surfaces.
On the other hand, the results of this study disagree with
the results from other studies.14,23-25 These differences
may be related to the different type of laser used, duration
of exposure, and energy applied to the surface.
Laser etching may have some advantages, but 1major
limitation of lasers for dental application includes cost of
laser units. They are still too expensive to be cost effective.
This study also compared the microtensile bond
strengths of specimens in the 10% maleic acid and 37%
orthophosphoric acid etched groups. The results have
indicated that there were no significant differences in
microtensile bond strengths between the 2 groups. The
results of this study are in agreement with the works of
Goes et al11 and Hermsen and Vrijhoef.12
For microtensile testing, the tensile bond strength is
dependent on the area of the bonded surface.28 In this
study, failures occurred mostly at the bonding resin/
enamel interface and did not involve the enamel or ceramic
except for the 2 specimens which showed cohesive
Fig. 3. Mean microtensile bond strength values of test groups; groups with different letters are statistically significantly different.
Table III. Microtensile bond strengths of cervical and
incisal specimens (MPa)
X SD
Group A (laser) Cervical 10.6 4.1
Incisal 13.5 4.2
Group B
(orthophosphoric) Cervical 8.3 3.7
Incisal 17.7 5.2
Group C (maleic) Cervical 7.6 3.3
Incisal 13.5 6.0
Group D (control) Cervical 5.7 2.5
Incisal 9.7 2.5
X, Mean; SD, standard deviation.
THE JOURNAL OF PROSTHETIC DENTISTRY USUMEZ AND AYKENT
28 VOLUME 90 NUMBER 1
failure within the enamel. Microtensile testing should
more closely approximate clinical applications.28 However,
microcracks and other defects can possibly occur
during the production of specimens with a slow-speed
diamond saw sectioning machine, which may cause premature
failure of the bond. Therefore the specimens
must be prepared carefully.29
Laser-treated enamel demonstrated strong bonding
to the porcelain laminate veneers. The highest microtensile
bond strength was achieved with 37% orthophosphoric
acid for the incisal sections while the highest
mean bond strength was achieved with laser treatment
for the cervical sections. It is believed that these differences
are due to exposure of the dentin layer in the
cervical portions of specimen because of decreased
thickness of enamel in this region. Visuri et al15 suggested
that the greater presence of peritubular dentin,
which has a greater mineral content than intertubular
dentin, may result in better bonding to the dentin. In
their study they obtained higher shear bond strength of
composite when it was bonded to Er:YAG laser-prepared
dentin compared with acid-etched dentin. Another
difference between acid etchant and laser actions
related to dentin is their effect on the structure of dentin
tubules. When an acid etchant is applied, the peritubular
dentin is preferentially etched, resulting in funnelshaped
openings to the tubules. This structure may contribute
with polymerization shrinkage to pull the tags
away from the walls. Laser irradiation produces no demineralization
of peritubular dentin and the dentinal tubules
remain open with no widening.21 This effect may
have contributed to microtensile bond strengths of cervical
sections where dentinal exposures were present.
Sources for the large deviations found in this study include
variations in enamel structure, storage effects, age,
condition of individual teeth, variations in enamel
depth, and nonhomogenous laser treatment of surfaces.
CONCLUSIONS
Within the limitations of this study, 37% orthophosphoric
acid (13.0 MPa)– and 10% maleic acid (10.6
MPa)–treated enamel surfaces showed statistically similar
bond strength values. Porcelain laminate veneers
demonstrated the highest bond strengths to 37% orthophosphoric
acid-etched (13.0 MPa) and
Er,Cr:YSGG hydrokinetic laser system-conditioned
tooth surfaces (12.1 MPa). The differences were not
statistically different.
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seven dentin adhesive systems. Dent Mater 2000;16:180-7.
30. O’Brien WJ, editor. Dental materials and their selection. 3rd ed. Chicago:
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[2thlaser]

Nice Ron,
Here’s the latest from UCLA….

Presented at the I3180 Bond Strength of Ceramic to Er,Cr:YSGG Laser Prepared Teeth
E.M. CHUNG1, E. SUNG1, A.A. CAPUTO1, M. COLONNA2, and I. RIZOIU2, 1 UCLA School of Dentistry, Los Angeles, CA, USA, 2 Biolase Technology Inc, San Clemente, CA, USA
Objectives: A previous study has shown that composite resin bond strength to primary dentin prepared with an Er,Cr:YSGG laser was comparable or higher than to carbide bur prepared dentin. The purpose of this study was to compare the shear bond strength of bonded ceramic restorations to Er,Cr:YSGG laser prepared and conventionally prepared teeth. Methods: Ten surfaces were prepared into dentin of extracted human molars using each of the following: a) Er,Cr:YSGG hydrokinetic laser (Biolase Technology Inc), b) medium coarse parallel diamond bur (Brassler) with a high speed handpiece (Midwest). Ceramic discs (IPS Empress, Ivoiclar), 4.2 mm in diameter and 2 mm thick, were cemented onto the dentinal surfaces with composite resin cement (RelyX Unicem Aplicap, 3M EPSE). Shear bond strength tests were performed using an Instron test machine. After testing, the failure surfaces of the teeth were examined under 20X magnification. The bond strength data were examined statistically using ANOVA and t-test. Results: The mean values of the shear bond strength of the laser prepared surfaces were 8.23 ± 1.92 MPa and 4.88 ± 1.02 MPa for the conventional bur prepared surfaces. Statistical analysis revealed significant differences between the two groups (p.<0.05). Failure locations varied between the dentin-cement interface and ceramic interface. No predominant location patterns were observed between the laser and bur prepared teeth Conclusions: Higher bond strengths were seen with the laser prepared teeth. These higher values may be due to micromechanical retention or increased surface energy. There was more variability with the laser prepared teeth, indicating the need for a finishing surface treatment with the laser.

Seq #339 – Cements: Dentin and Ceramic Bonding
10:15 AM-11:30 AM, Saturday, 13 March 2004 Hawaii Convention Center Exhibit Hall 1-2
ADR meeting in Hawaii in March…

We will continue to do more studies as time permits, and Eric and I discuss this study a bit more.

Mark

[Anonymous]

QUOTE

Quote: from 2thlaser on 1:04 pm on May 6, 2004
Conclusions: Higher bond strengths were seen with the laser prepared teeth. These higher values may be due to micromechanical retention or increased surface energy. There was more variability with the laser prepared teeth, indicating the need for a finishing surface treatment with the laser.

Mark

Mark, the finishing surface treatment refers to a very defocused laser application to remove the byproducts of abaltion (like Graeme recommends), correct?

As I don’t use Relyx, were the teeth etched?

Thanks for keeping us up to date with the post,

[Glenn van As]

What settings were used……….what wattage.

What tip.

What water concentration.

What air concentration.

What was the length of time used for the laser.

How defocussed.

Was the enamel scraped afterwards.

Just other questions I had. The information out there on bonding with lasers is fraught with all kinds of mistakes. There are some studies showing way lower bond strength (particularly class V restorations) and others showing equal bond strength.

Rare has it been shown to have higher bond strength.

Neat stuff though , but be very careful suggesting that the laser will increase bond strength as there are many many variables to the equation including what I asked about above.

Glenn

[2thlaser]

QUOTE

Quote: from Glenn van As on 6:46 am on May 7, 2004
What settings were used……….what wattage.

What tip.

What water concentration.

What air concentration.

What was the length of time used for the laser.

How defocussed.

Was the enamel scraped afterwards.

Just other questions I had.  The information out there on bonding with lasers is fraught with all kinds of mistakes.  There are some studies showing way lower bond strength (particularly class V restorations) and others showing equal bond strength.

Rare has it been shown to have higher bond strength.

Neat stuff though , but be very careful suggesting that the laser will increase bond strength as there are many many variables to the equation including what I asked about above.

Glenn

Glenn,
I can appreciate where you are coming from however, until you understand how a crown is prepared with the laser, it’s hard to describe. No contact is made on the tooth. The power settings were my normal settings of 5.5W, 60/30 air/water, and a G-4 tip. The time it took was about 4-6 minutes per tooth to preapare with the laser, mostly in a defocussed mode approximately 3mm from the tooth. When I prepare a tooth for a crown, it’s NOT perpendicular to the tooth, rather more parallel to the surface I am preparing. I prepared all the specimens myself, both with the laser and the high speed specimens. All UCLA, and Eric did was to test the shear strength, and the conclusions you have read. There may be many variables as you stated, but I think you ought to be careful in suggesting that the data might suggest otherwise. This was a VERY controlled study, mainly due to my inquisitive nature on how strong a surface I am creating with the laser for cementation vs. a drilled prepared surface. Now, not being a scientist, but a inquisitive dentist, I tried to take the variables out as much as I could. Oh, and to answer your last question, the surface was not “scraped”. Just a pure lasered surface for cementation, and then shear strength testing. Hope that helps you. I appreciate your questions….!

Mark

[jetsfan]

Mark .

For all of those old amalgams we remove with burs and finish off with the laser, perhaps you can quantify the benefit of actually using the laser, i.e, is the shear bond strength greater on a tooth that is just finished off with the laser in a defocused mode, than the tooth bonded without the laser treatment.

Robert

[Anonymous]

Mark, I think what Glenn and I were trying to get at with the questions is that if more details were available then your study could be compared ‘apples to apples’ with some of the other studies. Hopefully it could be discovered what was or wasn’t done in some of the other studies that showed less than stellar results.

I take it no scraping because you felt all the byproducts of ablation were removed by using the defocused mode, correct?

[2thlaser]

Correct.

[Glenn van As]

Hey Mark…….dont get me wrong. I admire your tenacity for the crown prep and also for doing these studies.

Kudos to you.

I am just being the devils advocate and telling you that even in Hibst review of hard tissue lasers he mentions that there are some diagramatically opposed viewpoints on the lasers effect on bond strength. I can give you quotes from my soon to be finished chapter (finally) but suffice it to say that if you look in the research , some of the bonding studies show lasers to be pretty abysmal with respect to bond strength.

I have seen some fascinating stuff on bone where there is an “ablation “layer in the SEM when using the laser in bone.

THis leaves a layer which even 18 months after the intial cuts in Rats (Aoki is the author) there still was the ablation layer visible in the histology on rats.

What does this have to do with bonding?

Well I sincerely believe that in many of the studies that a “ablation layer” was left behind particularly if there was no etch or Milicich scraping of the enamel after the laser was used.

You know how I feel about the cutting effects of the Er,Cr:YSGG vs the Er:YAG and the similarities.

I am proud of you for doing the research and am glad to see an article showing higher bond strengths.

All I was saying is to be careful when you evaluate the other studies that have been done on hard tissue lasers and bonding or microleakage (Class V) as there are alot of studies showing worse bond strengths or greater leakage with the laser…….

What did they do differently?

Interesting debate isnt it?

I still believe that with the proper technique, settings (not to high), scraping the enamel, and also etching that our bond strengths will be higher……..

I willl post one case before I turn in for the night…….

check out what the scope showed.

Grin

Glenn

PS I have the utmost respect for what you are doing, I am on your side full bore…….I think you have done more for my education in lasers than anyone perhaps except for Bob Gregg.

Just keep that in mind……….ok!!

Grin

Glenn

[Author]

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