Glass fibre reinforced bridges overcome

the problems of traditional metal frameworks

Traditional metal reinforced, resin bonded, fixed partial dentures (bridges) are characterized by certain basic disadvantages. These disadvantages culminate in the bonding and aesthetic problems of metal frameworks. Fortunately these problems can now be overcome by the use of fibre reinforced composites (FRC). FRCs offer a viable alternative for the preparation of resin bonded bridges (Vallittu J Prosthod 5 (1996) pp. 270-276, Goldberg and Burstone Dent Mater 8 (1992) pp. 197-202 and Giordano General Dent May/June (2000) pp. 244-249). The existing clinical data from direct and indirect use confirms the feasability of FRC in the preparation of resin bonded bridges.

Requiring better bonding....

One of the major problems associated with metal frameworks for bridges is debonding from the composite luting cement applied (Edeldorff et al. Quintessence Int 32 (2001) pp. 269-281). This problem is non-existent when using fibre reinforced composites. In fact, the bond strength obtained when using fibre reinforced Stick® products (Stick Tech Ltd., Turku, Finland) is 50 -100 % higher than the bond strength achieved with other materials and techniques (Kallio et al. Dental Materials 17 (2001) pp. 80-86.).

The bonding of the FRC material to the composite luting cement is based on the formation of an interpenetrating polymer network (IPN), which exists in StickTM and everStick® dental FRC materials (Stick Tech Ltd., Turku, Finland). StickTM and everStick® materials incorporate a multiphase polymer matrix containing both thermoplastic and thermosetting polymer resins. This allows the formation of an IPN layer between the composite luting cement and FRC material.

Metal frameworks may have adverse effects on surrounding soft tissue due to plaque accumulation and lack of biocompatibility. Also the aesthetic appearance, darkish appearance created by metal on the abutment teeth, is considered to be unattractive. In FRC restorations the fibres are translucent and covered with composites, creating aesthetic restorations, which do not increase plaque accumulation (Tanner et al. Biomaterials 22 (2001) pp. 1613-1618 and Waltimo et al. Int J Prosthodont 14 (2001) 457-460) and do not change colour long-term.

FRC materials can be used in direct (chairside) and indirect (laboratory) techniques. In the following text we have reported the experiences of some users; first using the direct technique, then the indirect technique.

CLINICAL DATA:
35 - 40 chairside bridges with
100% functional survival rate

Dr. Kari Pihlman (DDS, Restorative Dentistry) - together with his fellow workers in a Private Clinic, Läkkitori Dental Clinic (Espoo, Finland) - has used everStick products at the chairside since 2001. Dr. Pihlman, himself, has prepared 35 to 40 everStickC&B bridges chairside. All of these bridges are still functioning, which gives a total functional survival rate of 100%. All-in-all, Läkkitori Dental Clinic has prepared around 120 individual bridges.

Below, Dr Pihlman describes a case involving constructing fibre reinforced bridges for upper and lower arches using the direct technique. The work was done four years ago.

The patient was suffering from degenerative arthritis. She also had temporomandibular joint problems caused partly by her general illness and partly by an incomplete occlusion. It was decided that a glass-fibre reinforced bridge was to be constructed for both upper and lower jaws. Both of the bridges were made during the same appointment using the direct technique and impregnated everStick fibre reinforcements as the reinforcing material.

After 4.3 years the bridges are still functioning.

(See the clinical case)

LABORATORY DATA:
2703 laboratory restorations with 99.4% functional survival rate

The dental laboratory Dentrio in Tampere, Finland has been working with fibre reinforcements since 1998, keeping accurate statistics all the time.

"Since autumn 1998 we have made a total of 1225 fibre crowns, 787 pontics, 1306 adhesive bridges (e.q. surface retained, inlay and onlay bridges) and 172 veneers using Stick® fibre reinforcements. This is a total of 2703 crowns/bridges /veneers bonded to teeth", says Managing Director of Dentrio, Master Dental Technician Hannu Leppäkorpi. The laboratory’s experience with Stick® fibres is more than encouring, both due to the strength and the aesthetics of this fibre reinforcement material.

"By the end of December 2004, according to our knowledge, two pontics have fractured and 14 adhesive bridges fractured and debonded. This is under 0.6 % of all the cases we have done", Leppäkorpi concludes.