TUBULITEC
PRIMER/TUBULITEC
LINER
TUBULITEC PRIMER
consists of shellac (a natural resin) dissolved in alcohol with i.a. benzalkonium
chloride. The microthin layer (ca. 1/1000 mm) is not affected by the ethyl
acetate solvent in the liner.
Tubulitec Primer is hydrophilic, penetrates dried dentin, spreads out
into a thin layer and is easy to applied.
TUBULITEC LINER
Contains i.a. polystyrene and copaiba balsam dissolved in ethyl acetate
and is applied over the primer. It is most important that the liner covers
all the cavity walls and particulary the entire cervical margin. The risk
for leakage is greatest here because the dentinal tubules (ca. 20 000
per mm2) are crosscut and patent all the way to the pulp (sensitive dentin).
Furthermore there is frequently no enamel at the cervical margin.
The cervical contraction gap around large composite fillings can initially
be as large as 10-30 µm and may occasionally persist. But even much
smaller gaps can cause sensitivity and be just as dangerous to the pulp.
Most "bonding" systems do not bond adequately to the cervical
and the pulpal dentinal walls. A contraction gap filled with fluid is
formed and this can lead to complications: hypersensitivity to cold, pulpal
damage and possibly secondary caries.
TUBULITEC PRIMER and LINER can be used as
insulation under all conventional restorative materials. Several experimental
investigations have shown them to be excellent as "liners" under
composite materials and should be durable, provided resin impregnation
is used to eliminate a possible cervical contraction gap between the composite
and the insulation (see below). In experiments a gap has been observed
nearest the dentin in a few cases only.
TUBULITEC PRIMER and LINER do not preclude
the placement of retention grooves cervically; this should reduce the
risk of gap formation due to occlusal loading, flexibility of the material
or various kinds of stress. Retention grooves improve retention, reduce
leakage and reduce risk of fracture. Effective retention grooves may be
made with a notched chisel (see Fig. 1)
Comments on the latest research findings
It is clear that thick insulating liners such as calcium hydroxide pastes
no longer meet the requirements for effective insulation. They cannot
be used to insulate the cervical wall; the use of retention grooves is
precluded and retention of the restoration is reduced. They are partially
leached out. They do not prevent hypersensitivity and secondary caries,
etc.
Many of these disadvantages also apply to glass ionomer cement as a liner
under composite resin restoration. This cement is too acidic, it can open
the dentinal tubules and endanger the pulp. The composite can bond too
firmly to the "liner" and during setting contraction pull the
cement off the cavity walls. These phenomena have been observed in a number
of experimental investigations involving different types of GIC-cements,
including light-cured material. Some other varnish could be pulled of
the cavity walls when the composite contracts.
Note
For etching of ground, bevelled enamel walls with acid gel, 15 seconds
is adequate. An etched bevel further reduces the risk of leakage and markedly
improves the retention.
Enamel treated with fluoride does not reduce the effect of acid etching.
Tubulitec Primer and Liner are not effected by possible contamination
with acid gel.
The technique developed by Dr. Bengt Mattsson and which should be combined
with the ingenious Swedish idea of resin impregnation is simple and quick.
There are many indications that this method in combination with retention
grooves (see Fig. 1) and with some hygroscopic expansion of the composite
can greatly reduce an important biological disadvantage of Class II composite
fillings in premorals, namely hypersensitivity to cold, pupal damage and
secondary caries.
Treatment technique according to Mattsson:
The cavity and the surrounding tooth structure are cleaned with Tubulicid.
A foam pellet is then used to coat the cavity surface and the surrounding
enamel with Tubulitec Primer + Liner. Each application is dried carefully
with air.
The enamel is bevelled with a diamond point, at low speed and without
water spray; liner is removed only from the enamel which is to be acid
etched; the intact enamel is not exposed to the risk of contamination
by acid.
Acid, preferably in gel form, is applied to the enamel walls for 15 seconds,
and then rinsed with water, followed by air drying, then filling. Excess
resin, separated from the intact enamel by a layer of liner, is readily
removed.
Resin
impregnation of the gap
After setting contraction is almost completed, there is a gap filled with
air around the filling, especially at the cervical margins. A resin applied
to the surface will rapidly penetrate the gap by capillary attraction.
A thin excess of resin can usually be removed with a hand instrument because
the liner separates the composite from the tooth surface. If excess material
must be removed with a burr, it has been shown that a 12-bladed finishing
burr can be used without coolant; the gap at the surface is not blocked
by debris and it is still possible to impregnate the gap.
Contamination of the opening of the gap with fluid should be avoided;
fluid will be drawn into the gap and prevent resin impregnation. However,
it has been shown that even if saliva or water contaminate the opening
of the gap for a few seconds, application of a blast of air parallel to
the cervical gap for 20 seconds will clear the gap for resin impregantion.
A resin of low viscosity such as Enamel Bond (3M) is used and is applied
from one end of the cervical margin to the other. This should be continued
right around the cavity margins, because cracks may occur even near etched
enamel margins.
Penetration is rapid and excess plastic may be removed with a wet cotton
pellet or dental floss before it has set.
For light-cured composites, impregnation may begin as soon as the excess
composite filling material has been removed. For self-curing materials,
six to ten minutes should be allowed for most of the setting contraction
occur.
REFERENCES:
Brännström, M., Nordenwall K.-J., Torstensson, B., Hedström
K. G. & Wåhlstrand, H: Protective effect of polystyrene liners
for composite resin restorations. J. Prosthet dent No. 3, 1983.
Torstensson, B., Brännström, M., Mattsson, B.: A new method
for sealing composite resin contraction gaps in lined cavities. J. Dent
Res 64, 450-3, 1985.
Torstensson, B., & Brännström, M.: Composite contraction
gaps measured with fluorescent resin technique. Dent. Mater 4, 238-242,
1988.
Brännström, M., Mattsson, B. & Torstensson, B.: Unterfüllung
bei Kompositrestaurationen: Eine kritische Beuteilung. Quintessenz Seite
1-3, Februar 1988.
Brännström, M., Mattsson, B. & Torstensson, B.: Materials
techniques for lining composite resin restorations: a critical approach.
J. Den 19:71-79, 1991.
Blixt, M. & Coli, P.: The influence of lining techiques on the marginal
seal of class II composite resin restorations. In press.