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This month's On The Chair is a very interesting case presentation of a fractured tooth being rebuilt with a composite based post & core. Dr.Mona Kakar highlights a procedure to ensure good retention and final aesthetics. Post & Core Fabrication with Resin based materials and Reinforcing FibresFractured teeth have always presented a challenge to the dentist as far as reconstruction is concerned. The predictability of Root Canal Therapy as it is today, can retain almost indefinitely, even very badly broken teeth. The success of a dentist, however, lies in being able to restore the tooth in question, to maximum biting efficiency. Any treatment short of that is a failure according to the demanding standards of dentistry today. One of the widely accepted techniques involving restoration of extensively carious or badly fractured teeth is the fabrication of a post and core, utilizing the root canal space for anchorage. Thus far, the only materials that have been available to the dentist for this procedure, have been a variety of metallic alloys. Hard and unyielding, these metals have to be cast in the precise shape of the prepared canals and cemented into place. If too tight, they wedge the root and if too loose, they come off. Several intermediate steps in their fabrication (impression, poured cast, wax pattern, casting, finishing), are extremely conducive to errors being committed. Today, materials are available which eliminate all the intermediate steps, and control is rendered in the hands of the dentist, to fabricate on the chair, a resilient, aesthetic and bonded post-cum-core. One such material is the RIBBOND Bondable Reinforcement Ribbon combined with any dual cured composite based resin which in this case was Variolink..
A post and core was to be fabricated, followed by a metal free Jacket Crown. The post-cum-core was fabricated using RIBBOND and the jacket crown was fabricated with SCULPTURE, a metal free material for single crowns and reinforced bridges. RIBBOND is a leno woven ribbon made from a high modulus, high molecular weight polyethylene fibre, available in a variety of widths. The ribbon is virtually memory free and is thus pliable. The surface is specially treated so as to bond to, and become a part of any resin system.
This "monobloc" of tooth and reinforced composite resin, was then prepared in the usual fashion to receive a metal free crown. Crown margins were kept at the gingival margins since enough natural tooth structure was available to create a ferrule effect. A Jacket Crown was fabricated with the appropriate shades of the Fiberkor-Sculpture System from Jeneric Pentron. Utilization of opaquers was kept to a bare minimum since no metal was there to mask.
After cementation of the crown, neither the patient, nor his family could tell the previously damaged tooth from the normal. A satisfied patient and a satisfied dentist went to their homes that day. |
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A 15 year old boy came in
one week after he had a fall, sustaining injuries on his
chin and upper lip and fracturing his upper right central
incisor at the gingival one-third level with frank pulp
exposure. Radiographic examination revealed no fracture
of the root or the alveolar process. The tooth presented
without any mobility. The pulp was vital. The patient and
his family had high expectations concerning the
restoration of the tooth so as not to be distinguishable
from the adjacent, normal tooth. Root Canal Therapy was
performed.
Gutta percha
and sealer was removed from the root of the incisor for
12 mm from the incisal surface of the remaining coronal
structure. RIBBOND of 3 mm width was cut in two pieces,
one measuring 30 mm and the other, 28 mm in length. Each
piece was folded over to half it's length. Variolink dual
cured composite resin base and catalyst lengths were
dispensed. The entire length of prepared canal and the
incisal edge of the remaining stub was acid etched with
phosphoric acid (37%) for 15 seconds, rinsed and excess
water blown away. The bonding agent applied to the etched
surfaces was Prime & Bond 2.0 from Dentsply. After
curing of the bonding agent with the curing light, the
dual cured cement was mixed and loaded into a needle tip
of the Centrix Syringe System. Some mix was retained and
the ribbon strips were well soaked in the resin mix.
The canal space was
filled with the resin mix. The soaked, folded ribbon
strips were carried to, and inserted into the canal space
one after the other with the folded end draped over a
straight, blunt ended instrument. The longer strip was
inserted first and then the shorter strip was inserted.
This resulted in the entire canal space being occupied
with a bulk of RIBBOND material soaked and surrounded by
composite resin. Jutting out of the orifice end of the
tooth, were four 3 mm stub ends of RIBBOND individually
soaked in composite resin and surrounded by the back flow
from the excess in the canal space which had been filled
prior to RIBBOND insertion. These four protruding ends of
the RIBBOND strips formed the reinforcement for the core
build up to replace the lost coronal portion of the
tooth. 
The remaining resin mix
from the Centrix Syringe was extruded onto this framework
to create a core resembling the shape of a prepared
central incisor for a crown. It was ensured that the
space between the protruding ribbon ends was filled with
resin so as not to leave any voids. Composite resin was
also placed so as to cover the ribbon ends completely and
leave none of them exposed on the outer surface of the
core. All the material was thoroughly light cured to
create an external set surface. The material was left in
the mouth for a couple of hours to ensure complete set of
the self curing component of the resin mix.
What emerged from this procedure was a
post-cum-core (single piece), which was bonded onto the
root, creating a solid structure without any wedging
effect on the root. Moreover, the resin conforming to the
inside shape of the canal space ensured no voids and
eliminated "fitting" problems normally
associated with cast post and cores. The bands of RIBBOND
reinforced the resin material and made it extremely
strong and durable. Bonding of the entire entity also
created a monobloc, which is the essence sought for
favourable occlusal force transmission and for resistance
against debonding of the entire unit. Best of all, there
was no metal to mask with the crown since the base shade
of the composite was a close enough match to the tooth
and was translucent. The RIBBOND strips, though opaque,
were white in colour and after being completely encased
in the composite, were not visible anyway. However, they
did not contribute to the colour of the core in any
adverse way.
The result was a crown
with all the requisite translucency and shade matching
with the adjacent central incisor. This crown was
cemented to the tooth with the same dual cured composite
resin system, i.e., Variolink.