Amalgam repair

Amalgam repair

Boondarick Niyatiwatchanchai

Tuesday, August 13, 13

Replacement of
restoration


Replacement of
restoration
• secondary caries
• marginal defect
• cusp fracture


Replace or repair


Replace or repair
•
•
•
•
•
•

loss of dental tissue
increasing preparation/restoration size
cost
time consuming
technically difﬁcult
Potentially damage to pulp

Beneﬁt of repair
• more conservative of tissue
• reduce risk of iatrogenic damage
• reduce need for the use of local anesthesia
• oppotunity to enhanced patient experience
• saving in time and resources
•

esthetic


Resin composite as repair
material

• interfacial bond between amalgam and resin
composite

• strengthening of the tooth-material
interface

• veneering of amalgam for esthetic


Development in adhesive
technology

• Improve sealing quality of amalgam repair


Still controversy
• still in wide range of result attributed to

various factors ex time , interface , effect of
roughening , type of alloy


Aim of the study
• to assessed the repair quality of amalgam

restorations at the amalgam-resin and resin
tooth interfaces

• using different
• 1) surface ﬁnishing methods
• 2) adhesive systems

Methods and materials
• 55 caries-free intact human molars
• stored in distilled water
• clean and polished with pumice and rubber
cup for 10 sec

• occlusal cavity preparation using high speed
hand piece with air/water spray


•

Average facio-lingual width of cavies was approximately
one-third of intercuspal width and 3 mm depth

•

restored with high copper , microfine lathe-cut
amalgam(Cavex Avalloy)

•
•
•
•

stored in distilled water for 24 hrs

•

divided into 5 groups( n=10/group) to receive the
following adhesive system


thermo cycling in deionized water
remove mesial and distal parts of the cavities
one side was finished with a coarse diamond bur while
the other was finished with fine diamond bur

•

Group 1: All Bond 3 (BISCO, Inc, Schaumburg, IL, USA)
(dual cure, etch&rinse adhesive system)

•

Group 2: Clearﬁl SE Bond+Alloy Primer (Kuraray,
Okayama, Japan) (self-etch adhesive system with alloy
primer)

•

Group 3: Kuraray DC Bond (Kuraray) (dual-cure, selfetch adhesive system)

•

Group 4: Xeno V (Dentsply DeTrey, Konstanz, Germany)
(one-step, self-etch adhesive system)

•

Group 5: XP Bond (Dentsply DeTrey) (etch&rinse, selfpriming adhesive system)

All of the cavities were restored with resin composite (TPH
Spectrum, Dentsply DeTrey) and light polymerized with a
halogen light of 500 mW/cm2 intensity

•
•
•
•
•

Thermocycled again

•
•

digitally photographed


immersed in 0.5 basic fuchsin soluion 24 hr
rinsing with distilled water
embedded in epoxy resin
sectioned mesiodistally with a slow speed diamond
saw
data analyzed with one-way ANOVA and poist hoc
Tukey test

Result
• All the groups exhibited microleakage

between the amalgam-resin interface and
the tooth-resin interface


Result
•

there was no difference among each region when
using all bond 3

•

no statistical difference between the microleakage
values of surfaces with either course or ﬁne
ﬁnish(p>0.05)

•

amalgam-resin surfaces exhibited statistically more
microleakage than tooth-resin surfaces for the
other adhesive systems


DISCUSSION
• Amalgam comprises about 40% of the

restoration being replaced with a median
age of 12-15 years

• A successful technique for the repair
would be advantageous conservative


Alternative options for defective
amalgam restoration

• Rapairing
• Sealing
• Refurbishing


DISCUSSION
• Replacing ditched amalgam restorations

with other similar restorations resulted in
signiﬁcant dental structure loss

• Previous studies report on 40%-70% bond
strength archieved from amalgam-toamalgam repair

• The trend of minimally invasive dentistry

DISCUSSION
• In Vivo studies related to the repair of

amalgam indicate a signiﬁcant impact on the
improvement of clinical performance of
amalgam restoration with minimal
intervention


Important factor
• Interfacial bond between the joined
surfaces

• clean surfaces , roughening amalgam ,
adhesive for metallic


Microleakage test
• useful methods for evaluating sealing
performance of adhesive systems

• image analysis to obtain quantitative results


Effect of roughening
• Jessup and Vandewalle report improved
bond strengths after roughening with
carbide burs

• Hadavi and others report similar result
using carbide burs and diamond burs

• However the results of the current in vitro

study could not correlate microleakage and
surface roughness of the joined surfaces


Use of bonding agent
• Robert and others found the use of a

bonding agent did not improve the degree
of protection against microleakage

• Ozer and others found signiﬁcant

improvement in microleakage especially
amalgam-resin interface


Bonding systems
• Etch and rinse
• Self etch


Etch and rinse
• Phosphoric acid etching of enamel and
dentin

• weak zone of uninﬁltrated dentin
• hydrolytic degradation of collagen


Self etch
• increasing popularity
• reduces application time and technique
sensitivity

• prevent hydrolytic degradation of bond
• debate on efﬁcacy of bonding to enamel


In this study
• Total etch performed signiﬁcantly better
than self etch

• alloy primer did not signiﬁcantly improve
sealing in the restoration comolex


All bond 3
• Hydrophobic , radiopaque-ﬁlled bonding
resin and also HEMA-free

• less prone to water sorption
• Hydrophobic adhesives are expect to be
more durable


• Better performance of etch and rinse

systems may also be related to
micromechanical interlocking of the resin
system to acid etched surfaces

• However additional roughening with coarse
bur did not facilitate bonding both in
amalgam and tooth surface


Conclusion
• In term of preventing microleakage etch
and rinse adhesive may be preferred for
amalgam repair

• The use of coarse versus ﬁne diamond for
preparation did not impact microleakage


Primary Aim
• To evaluate the effects of different amalgam

conditioning methods on the tensile bond
strength between amalgam and a
nanohybrid resin composite restorative
material , using various intraoral restoration
repair systems

• Study the nature of interfacial bond failure ,
using electron microscope


Null Hypothesis
• There was no statistical difference in repair
bond strengths between the various repair
protocols


ion, which suggests that the fractured tooth is
restorative procedures.12 Various factors may
o cusp fracture of amalgam-restored teeth,
k of adhesion of amalgam to tooth structures,
iding no significant change in the fracture
the cusps14 or in the amount of cuspal flexure15
uivalent unrestored teeth. These factors may be
by the presence of undermined cusps, extensive
ze, parafunctional activity, impact load, fatigue
lusal disharmony.9
ional approach to the management of cusp
eth which have been restored with amalgam has
otal restoration replacement resulting in more
ect restorations, or preparation for indirect
Both of these procedures result in increased
nd restoration size.16 This approach has been
the ‘repetitive restoration cycle’17 and can result
ssive weakening of the tooth through unnecesof sound tooth tissue, detrimental effects on the
together with potential damage caused to
h.18
me amalgam restorations with adjacent cusp
bly those associated with an extensive secondon, will inevitably require replacement, it may be
t some amalgam restorations with adjacent cusp
be given extended longevity through repair
.e. cusp replacement with or without partial
of the amalgam restoration, allowing preservaortion of the restoration that presents no clinical
hic evidence of failure). This more conservative
vasive approach to the management of cusp
cent to or involving the amalgam restoration,
advantages, including:

the tensile bond strength between amalgam and a nanohybrid
resin composite restorative material, using various intra-oral
restoration repair systems. The secondary aim was to the
nature of interfacial failure, using scanning electron microscopy (SEM) and profilometry examinations of failed interfacial
surfaces. The null hypothesis tested was that there was no
statistical difference in repair bond strengths between the
various repair protocols.

Material and methods

•

2.

Materials and methods

2.1.

Specimen preparation

Specimen preparation

One hundred and sixty poly(methymethacrylate) (PMMA)
retention bases (Mould 1) (VisionTek Systems Ltd., Chester,
UK) were prepared containing a central recess (width 5 mm,
height 5 mm, depth 4 mm). A cavity of 2 mm diameter and
2 mm depth was prepared at the base of this central recess, to
facilitate mechanical retention of the amalgam (Fig. 1). The
amalgam (non-gamma 2, lathe-cut, high-copper alloy with
43% Ag, 25.4% Cu) (ANA 2000 Duet, Nordiska Dental AB,
Angelholm, Sweden) was triturated according to the manufacturer’s instructions and then condensed with a hand
instrument into the recess within the PMMA base. Specimens

•

160 PMMA retention bases were prepare containing a central
recess(width 5mm , height 5mm , depth 4mm)

•

cavity of 2mm diameter and 2mm depth was prepared at the base

rvative of tooth tissue,
k of iatrogenic damage,
ed for the use of local anaesthesia,
y for enhanced patient experience,
ime and resources.

t to amalgam repair procedures using bonded
e use of resin composite as a repair material


Fig. 1 – Custom made retention base (Mould 1).

•
•

Triturated amalgam(non gamma2 , lathe-cut, high copper)

•
•

Allow to set for 24 h

•
•

Air-dried for 24 h


condensed with a hand instrument into the recess within the
PMMA base

polished with a wet 1200-grit silicon carbide disc at 300 rpm
for 30s and cleaned for 10 min in ultrasonic bath

stored in artiﬁcial saliva for 2 weeks to present an aging
process

Surface conditioning method

• Divided into 8 groups , each containing 20
specimen


1 Group 1: Air-borne particle abrasion with 50 mm Al2O3 (Korox R, Bego, Bremen,
Germany) using an intraoral sandblaster (Dento-PrepTM, RØNVIG A/S, Daugaard,
Denmark) from a distance of 10 mm at a pressure of 2.5 bar for 4 s followed by
application of Alloy primer (Kuraray, Japan) and Panavia 21 (Kuraray, Japan).
2 Group 2: Air-borne particle abrasion as for group 1 followed by application of
Amalgambond Plus (Parkell, USA).
3 Group 3: Air-borne particle abrasion as for group 1 followed by application of ALLBOND 3 (Bisco, USA).
4 Group 4: Surface roughening with a diamond bur (Classic Diamond #521M, Dental
Directory, Essex, UK) for 10 s and application of Alloy primer (Kuraray, Japan) and
Panavia 21 (Kuraray, Japan).
5 Group 5: Diamond bur roughening as for group 4 followed by application of
Amalgambond Plus (Parkell, USA). Group
6 6: Diamond bur roughening as for group 4 followed by application of ALL-BOND 3
(Bisco, USA)
7 Group 7: Silica coating with 30 mm SiO2 particles using an intra-oral sandblaster
(3M ESPE, Germany) from a distance of 10 mm at a pressure of 2.5 bar for 4 s
followed by application of the corresponding silane and bonding agents (ESPE-Sil and
Visio-bond) of the CoJet System (3M ESPE, Germany)
8 Group 8 (control group): No surface conditioning and no adhesive system was used.

17

journal of dentistry 40 (2012) 15–21

Table 1 – Description, composition and manufacturers of the intra-oral adhesive repair systems and composite resin
material used in this study.
Material

Material description

Alloy Primer +
Panavia 21

Metal conditioning primer
+ dual-cure adhesive system

Amalgambond Plus

Self-cure etch and rinse
adhesive system

ALL-BOND 3

Dual-cure etch and rinse universal
adhesive system

CoJet-Sand

Sand for coating substrate surface

ESPE-Sil

Silane coupling agent

Visio-bond

Adhesive bonding agent

NANOSITTM

Nano-hybrid composite resin
restorative material

Chemical composition
Primer: 6-[(4-vinylbenzyl)propylamino]-l,
3,5-itriazine-2,4-dithione (VBATDT),
10-methacryloyloxydecyl dihydrogen
phosphate (MDP adhesive monomer)
Adhesive system: 10-methacryloyloxydecyl
dihydrogen phosphate, dimethacrylate,
silica ﬁller
META (4-methacryloxyethyl trimellitate
anhydride), bisphenol-A-dimethyacrylate,
HEMA (hydroxyethyl methacrylate),
ethylene glycol methacrylate
BisGMA (bisphenol-A-dimethyacrlate),
urethane dimethacrylate, triethylene
glycol dimethacrylate, silica ﬁller
Aluminium trioxide particles coated
with silica, particles size: 30 mm
3-Methacryloxypropyltrimethoxysilane,
ethanol
Bisacrylate, aminodiol methacrylate,
camphor-quinone, benzyl dimethyl
ketale, stabilisers
BisGMA (bisphenol-A-dimethyacrylate),
HEMA (hydroethyl dimethacrylate),
inorganic glass particles (57 vol%; 74 wt%),
particle size: 2.0–0.2 mm

were allowed to set for 24 h at 23.0 Æ 1.0 8C and were
subsequently polished with a wet 1200-grit silicon carbide
disc (Struers RotoPol 11, Struers A/S, Rodovre, Denmark) at
300 rpm for 30 s and cleaned for 10 min in an ultrasonic bath
(Quantrex 90 WT, L&R Manufacturing Inc., Kearny, NJ, USA)
Tuesday, August 13, 13 deionised water to eliminate possible contamicontaining

Manufacturer
Kuraray, Okayama, Japan

Parkell, Farmingdale, NY, USA

Bisco, Inc. Schaumburg, IL, USA

3M ESPE AG, Seefeld, Germany

Nordiska Dental AB, Angelholm,
Sweden

Group 6: Diamond bur roughening as for group 4 followed by
application of ALL-BOND 3 (Bisco, USA).
Group 7: Silica coating with 30 mm SiO2 particles using an
intra-oral sandblaster (3M ESPE, Germany) from a distance
of 10 mm at a pressure of 2.5 bar for 4 s followed by
application of the corresponding silane and bonding agents

Repair resin composite application

•

An additional 160 PMMA retention base were
prepared and use for the resin composite
application procedure

•

Mould 2 was placed onto the surface of
conditioned amalgam specimen

•

Pack nanohybrid composite against the amalgam in
2 mm increment

•

Polymerized with light for 40 s



Fig. 2 – Custom made retention base (Mould 2) positioned
over Mould 1 containing the surface conditioned amalgam
specimen surface conditioned amalgam specimen.

2.4.


Tensile testing

The PMMA moulds retaining the amalgam–resin composite
specimens were mounted on a universal testing machine
(Lloyd Instruments Ltd. Model LR5K, Hampshire, UK) fitted
with a 1 kN load cell, travelling at a crosshead speed
of 0.5 mm/min. A tensile force was applied until failure
occurred. The data were subjected to statistical analysis
using a Resin composite packed into Mould 2 and packed
Fig. 3 – one-way analysis of variance and post hoc Tukey’s
test.
against surface conditioned amalgam specimen in

Fig. 3 – Resin composit
against surface conditi
underlying Mould 1. Am
Mould 1.

was defined as a fractu
and cohesive failures.
The failed surfaces
specimens from each te
dimensional profilomet
profiles at the failed su
value (Ra-value) of amalg
following failure was d
profilometry (ProScan-20
UK). Scanning was con

• store for 24 hrs at room temperature
• tensile stress testing using universal testing

machine(Lloyd instruments Ltd.) ﬁtted with
a 1 kN load cell , travelling at a crosshead
speed of 0.5 mm/min

• Apply force until failure occurred
• Data analysis using one-way analysis of
variance and post hoc Tukey’s test


Failure analysis
• The surfaces of three randomly specimen
from each group were examined under
SEM

• Investigate the surface morphology of the
failed surfaces

• Failures were classiﬁed as adhesives ,
cohesives or mixes


Failure analysis
•

Adhesive failure a complete debonding of the
adhesive system from the treated amalgam surface

•

Cohesive failure was deﬁned as a fracture that
occurred in the resin composite and showed
remnants of bonding agent or resin composite on
both sides

•

Mixed failure deﬁned as a fracture that showed
evidence of adhesive and cohesive failure


Result
• Bond strength
• control group = 0 (no adhesion)
• Sandblasting and alloy primer and Panavia
21 resulted in signiﬁcantly higher bond
strength values than other


bonding agent or resin composite on both sides. Mixed failure

use of Alloy primer and Panavia 21 resulted in significantly

Table 2 – Comparison of mean tensile bond strengths (TBS) and surface roughness values between repair protocols.
Surface conditioning method

Group
Group
Group
Group
Group
Group
Group

1
2
3
4
5
6
7

Alumina sandblasting + Alloy Primer + Panavia 21
Alumina sandblasting + Amalgambond Plus
Alumina sandblasting + All Bond 3
Diamond bur + Alloy Primer + Panavia 21
Diamond bur + Amalgambond Plus
Diamond bur + All Bond 3
Silica coating (CoJet-system)

TBS (SD) [MPa]

5.13
2.51
2.42
3.42
3.40
1.34
3.72

(0.96)
(2.73)
(0.76)
(0.82)
(1.68)
(0.71)
(1.00)

95%
confidence
intervals (MPa)
5.71–4.58
3.72–1.27
2.87–1.99
3.78–3.09
4.06–2.75
1.60–1.10
4.24–3.22

Statistical
groupings
d
c
a,b
b,c
b,c
a
b,c

Ra-value
(mm)
4.76
3.58
2.35
16.56
16.03
13.46
1.95

Lower case letters indicate statistically homogeneous groups. If two data sets share the same letter, they do not differ to a statistically
significant degree.

All bond3 present lower bond strength compared to
other conditioning methods where aluminar sand
blasting was used
No significant difference between the bond strength
values of Cojet system , diamond-panavia system or
diamond bur-amalgabond plus


Failure analysis
• All specimen failed adhesively
• The roughness of the specimen prepared

by alumina sandblast was less than the
diamond bur , Cojet silicatization produced
the lowest surface roughness


Failure analysis


Fig. 4 – SEM images of amalgam surfaces treated mechanically with (a) alumina sandblasting, (b) diamond bur and (c)

19

Discussion
• Repairing an amalgam restored tooth

exhibiting signs of single or multiple cusps
fracture can result in extend longevity of
the existing restoration

• In the case of cusp fracture it is often

aesthetically favourable to veneer the
amalgam with tooth-coloured material


•

Important factor in the quality of amalgam repair is
the interfacial bond between the joined surfaces

•

Previous studies suggested that shear bond
strength testing has limitation

•

The basic selection of the adhesive repair system
used in the current study was their demonstrated
ability to bond to metal

•

In contrast to previous study , the finding of
current study indicated that surface roughness of
the amalgam substrate appears to have significant
influence on its repair bond strength


• Alumina sandblasting and silicatization
cause micro retention feature

• Diamond bur yields “macro” and “micro”
retentive features

• Without use of adhesive , greater repair

strength may be anticipated from the
substrates yielding macro retentive feature


•
•

due to better inﬁltration and improved physical
interlocking

•

Alumina sandblasting and silicatization remove
large surface asperities and provide a more
homogenous surface with major defects and stress
concentration removed

•


With the use of adhesive , a better surface wetting
was found occur with the micro-retentive
amalgam surface

high degree of roughening(13.5-16.6um) induced
by tx with diamond bur is likely to induce surface
defect and area of concentration , deep asperities
which adhesive may not fully inﬁltrate

•

Previous studies have highlighted higher interfacial
bond strengths between amalgam and resin
composite where low surface roughness values
were induced

•

In this study a lower surface roughness induced by
alumina sandblasting in combination with Panavia
21 adhesive system resulted in a signiﬁcantly higher
tensile bond strength compared with the Panavia
21 but prepared with a diamond bur

•

This may suggest that improved surface
homogenity implicit in the removal of large surface
defects associated with alumina sandblasting
improved adhesive bond to formed between 2
surfaces


Conclusion
•
•

2. The combination of alumina sandblasting of the
amalgam surface followed by the application of the
Panavia 21 adhesive system exhibited signiﬁcantly
higher tensile bond strengths than other repair
protocols tested

•

1. The tensile bond strengths of resin composite to
amalgam varied with the degree of amalgam
surface roughness and the type of conditioning
technique employed.

3. Interfacial failure between amalgam and resin
composite was of adhesive nature, irrespective of
the repair protocol employed.

• ขอบพระคุณ อาจารย์ชัยศรี ธัญพิทยากุล

Amalgam repair

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