Bridge (dentistry)
[3] Resin-bonded bridge: A dental prostheses where the pontic is connected to the surface of natural teeth which are either unprepared or minimally prepared.
In these types of bridges, the abutment teeth require preparation and reduction to support the prosthesis.
Conventional bridges are named depending on the way the pontic (false teeth) is attached to the retainer.
A resin-bonded bridge utilises retainer "wings" on the sides of the pontic which attach it to the etched enamel of the abutment teeth.
Subsequently, a diagnostic wax-up can be provided to help the patient visualise the final prosthesis and to construct a silicone index.
Endodontically treated teeth have lost a large amount of tooth structure, weakening them and making them less able to tolerate additional occlusal loading.
[3] For resin bonded bridges abutment teeth should ideally be unrestored and have enough enamel to support the metal wing retainer.
It is advised to replace old composite restorations prior to cementation to provide optimum bond strength via the oxide layer.
Once stable periodontally compromised teeth may be used as abutments, depending on the crown to root ratio described below.
Roots that curve apically provide increased support compared to those which have a fixed taper.
[4] The number of abutments required depends on both the position of the tooth to be replaced and the length of the span.
Choosing pontics with increased occlusogingival dimension and using high yield strength alloys to construct the prosthesis will help reduce deflection.
Due to the poor aesthetics of this design it is most commonly employed to replace mandibular molars.
To minimise coverage of the soft tissues the lingual/palatal portion of the pontic is reduced to improve accessibility for maintaining good oral hygiene.
[3] The ovate pontic comes into contact with the underlying soft tissue and hides the defects of the edentulous ridge with applying light pressure.
[15] It is commonly used in provisional bridges following extraction of teeth to improve the emergence profile and helps in shaping the gingiva around the future fixed prosthesis.
[17] Provisional restorations are designed to be used for a few weeks to months, they can be fabricated directly (by chair side), or indirectly ( in the dental laboratory).
It is usually tried in a few times to check if it fits properly and if its margins are well adapting on the teeth surface and gingiva, it may need relining or a few adjustments.
Also, commonly used resins include the BisGMA based dimethacrylate, and the visible light urethane di-methylacrylate.
[18][19] Dimethacrylate-based materials were found to be better than monomethacrylates for temporary restorations in terms of flexural strength and hardness.
[20][21] Acrylic resin was the first veneering material used to help restore the aesthetics of crown and bridges.
The aim was to maintain a similar colour to natural teeth by attaching it on the labial surface of metal crown / bridges; however, resin-veneered dental prosthetics lacked stability and abrasion resistance.
IPs Emax ceramics offer high aesthetic properties, which is why its use has been increasingly popular.
[28][29] Reports found that the 3×3 mm designed connectors in zirconia bridges increased the strength to resist fracture by 20%.
[30][31] Although the use of ceramic based fixed prosthesis have been popular as it achieves a lifelike, highly esthetic appearance, a Cochrane Review found insufficient evidence to support or refute the effectiveness of ceramic materials for fixed prosthodontic treatment over metal-ceramic.
[32] As with single-unit crowns, bridges may be fabricated using the lost-wax technique if the restoration is to be either a multiple-unit FGC or PFM.
They can usually be completed in only two dental appointments, restore the tooth back to full chewing function, require no periodic removal for cleaning, have a long life-expectancy and are aesthetically pleasing.
