Influence Of Adhesive Systems On The Bonding Of Dental
Amalgam To The Glass Ionomer
** Dr. R. Nageshwar Rao
Prof. & H.O.D
* Dr. Ravikumar K. (Post Graduate)
Two adhesive systems All-Bond II Clearfill Liner Bond II were used to
evaluate the bonding strength of amalgam to the glass ionomer. Glass ionomer
cement was mixed into a paste and applied to the retentive cavity of acrylic matrix.
Adhesives are prepared according to the manufacturer’s recommendation and
applied on to the surface glass ionomer cement and amalgam was condensed over
the adhesives with counter matrix in position. Bonded assemblies were stored in
24 hour and 30 days period in 37 degree and 100% humidity. Specimens were
loaded in tension to failure on a universal testing machine with a cross head speed
of 6mm per min. the result obtained were analysed statistically and mean tesnile
strength was compared with two adhesives and two different storage periods.
There was no significance change observed. The adhesive systems between
amalgam and glass ionomer cement in this study proved to be useful in providing
retention for amalgam restorations.
Influence Of Adhesive Systems On The Bonding Of Dental
Amalgam To The Glass Ionomer
The development of restorative bonding materials used in posterior teeth
has not met all necessary conditions to be considered an ideal dental restorative
technique. Amalgam has served effectively as a dental restorative material since
its introduction. It has many advantages, including ease of manipulation, long
clinical service, and low cost, compared with most other materials. However
amalgam has got its own set of disadvantages, such as its colour, possible mercury
toxicity. In particular, lack of adhesion to tooth structure is the short coming that
has omitted its effective use in certain situations.
With falling level of dental carious in the population and ja greater
awareness of the shortcomings of restorations in carious management. The dental
profession is becoming more aware of the need to define precise criteria for
placing or replacing restorations. At the same time cavity design and perception of
the requirements of cavity preparation continue to evolve and there appears to be a
global trend towards the teaching of increasingly conservative cavity preparations.
This relates partly to the greater use of adhesive systems for restorative procedures
involving a variety of materials.
Glass ionomers are being used increasingly as liner/bases under amalgam
restoration as they leach fluoride, bond to dentin, and have a low coefficient of
thermal diffusivity. If an adhesive bond could be formed between the amalgam
and the glass ionomer then the performance of amalgam restorations might be
improved further. The purpose of this study is to evaluate tensile bond strength of
the amalgam to the glass ionomer under the influence of two adhesive systems
All-Bond II (Bisco Dental) and Clearfill Liner-Bond II.
Materials and method
Materials use were
1. Glass ionomer cement (Fuji II)
2. ALL-Bond II adhesive (Bisco dental)
3. Clearfill Liner Bond II (Kurray Co.)
4. Zinc free high copper amalgam alloy (DPI Non-Gamma-2)
Twenty eight experimental samples were divided in to two groups:
1. All Bond II and
2. Clearfill Liner Bond II of this seven repetition of each for 24 hour and 30 days
The glass ionomer was prepared in accordance with the manufacturer’s
instructions. (The standard powder to liquid is 2.7/1.0 gm one level scoop of
powder to one drop of liquid). The mix was applied to the interior of a retentive
cavity of a clear acrylic matrix (2mm height and 5x5 mm area) Acrylic counter
matrix was adopted to the matrix to provide 1mm of overlap in the height of the
glass ionomer cement test specimen. The glass ionomer cement was cured for 20
min. The adhesive systems All-Bond II and Clearfill Line Bond II were
manipulated according to the manufacturer’s recommendations and applied on the
glass ionomer cement. Before the initial set matrices were juxtaposed and the
dental amalgam was immediately condensed. Silver amalgam alloy and mercury
were proportioned at 1:1.1 in weight in accordance with the manufacturer’s
recommendations and then mixed for 10 sec with a mechanical mixer (Degussa)
and a standard technique was used to manually condense the amalgam triturate on
to the adherent surface of the glass ionomer cement. After 24 hour and 30 day
storage period in an environment of 37 degree and 100% relative humidity. The
samples were tested in a Universal Testing Machine at cross head speed of 6mm
per minute. The test specimen was loaded in tension to failure and bond strength
was calculated from the load required to cause de-bonding divided by the area of
the adherent surface.
The table no. 1 and 2 represents the mean tensile strength value of the two
different adhesive systems. According to the storage period of bonded assembly.
To compare between the two adhesives and storage period student t-test was
applied to test significance difference between two material and storage periods. It
has showed that there is no significance difference between 24 hour and 30 days
storage period on two adhesives separately at 5% level significance (p>0.05) and
also between adhesives on 24 hour and 30 days showing statistically non
significant difference at same level of significance (p>0.05) as shown in the table.
Table No. 1: Comparison of means of tensile strength between 24 hour and
30 days by two adhesive materials separately (In Kilograms / Square cm.)
Material Days Mean S.D. t-value p-value Significance
All Bond II 24 hrs 33.3586 2.0893 1.6277 >0.05 NS
30 days 34.9529 1.5329
Clearfil Liner Bond II 24 hrs 32.9227 1.6617 1.2537 >0.05 NS
30 days 34.3214 2.4393
Table No. 2: Comparsion of means of tensile bond strength between two
adhesives by 24 hours and 30 days period (In Kilograms / Square cm.)
Days Material Days Mean SD t-value p-value Significance
24 All Bond II 24 hrs 33.5386 2.0893 0.4318 >0.05 NS
Clearfil Liner Bond II 30 days 32.9227 1.6617
30 All Bond II 24 hrs 34.9529 1.5329 0.5799 >0.05 NS
Clearfil Liner Bond II 30 days 34.3214 2.4393
In case of deep carious lesion which are to be restored with dental amalgam
restorations cement base are provided to act as thermal insulations. There are
various types of materials are used as base for amalgam restorations. Presently
glass ionomer cements are being used as a base. By using glass ionomer we can
achive some retention for amalgam. Recently as the adhesive systems are findings
more applications in the dental restorative procedure, like in case of large carious
lesions which are to be restored with amalgam restorations. Removal of carious
will not always result in a cavity preparation with enough resistance and retention
form to hold the amalgam effectively in the cavity. A procedure that All Bond II
and Clearfill Liner Bond II adhesive to promote silver amalgam bonding to the
tooth has recently been used and results demonstrated a bonding strength similar
to those obtained from composites. There are studies conducted by Mauro A. De.
Arrodo. Nobillo and Y.E.Y. Aboush., R.J. Elderton on bonding amalgam to the
glass ionomer using adhesives. In evaluating influence of adhesives in bonding
amalgam to glass ionomer our study showed no significant difference between
All-Bond II adhesive and Clearfill Liner Bond II adhesive and also no significant
difference obtained in comparing these adhesives with 24 hour storage period and
30 days storage period. It has been reported by Stainec M. Holt M. that the
bonding mechanism of adhesives to metallic structures consists of mechanical
retention and chemical interaction through hydrogen bridges and same mechanism
of bonding reported with bonding dental amalgam. This can be explained through
the development of large cement tag formation with the amalgam structures. When
it is condensed in the cavity while the adhesive cement is still plastic demonstrates
that mechanical interlocking occurs. Ideally these adhesives are developed in
accordance with heterogeneous tooth structures consisting of organic and in-
organic material where as glass ionomer presents homogenous surface for these
adhesives when different adhesives systems are used. It may be due to this factor
that there was no significant difference obtained in the tensile strength between the
two adhesive systems when used between amalgam and glass ionomer. When the
glass ionomer powder and liquid are mixed to form paste calcium aluminium
sodium and fluoride ions are leached into the aqueous medium. The polyacrylic
chains are cross linked by the calcium ions and forms a solid mass within 24 hours
a new phase forms in which aluminium ions become bound within the cement
mix. This leads to a more rigid set cement. During this maturing process if
adhesives are applied, water that is being used as the medium may slowly hydrates
both cross linked matrix and part of the adhesives simultaneously there by
increasing the adhesive strength between glass ionomer and adhesives.
Bond can be achieved with the help of adhesive systems which may
enhance the retentive ability of amalgam restorations thus in near feature it might
be possible to recommend even more conservative cavity designs using glass
ionomer and amalgam in combination with adhesives to achieve better results.
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curing glass-ionomer liner/base. Br. Dent. J., 1991; 170-219.
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