A dental bridge is a fixed prosthetic device used to replace one or more missing teeth, restoring function and appearance. It bridges the gap created by lost teeth by joining an artificial tooth to adjacent natural teeth or implants. This restoration is permanently cemented into place and cannot be removed by the patient. The materials used determine its strength, appearance, and expected lifespan.
The traditional fixed bridge design consists of two main structural parts. The replacement tooth, or teeth, is known as the pontic, which fills the space left by the missing natural tooth. On either side of the pontic are the abutments, which are the supporting structures that anchor the entire prosthetic.
The abutments are typically crowns placed over the natural teeth adjacent to the gap. The abutments and the pontic are fabricated as a single, continuous unit. While the entire bridge functions as one piece, the material composition may vary between the substructure and the visible exterior surface.
Defining the Components of a Dental Bridge
The pontic is the artificial tooth suspended between the abutment teeth. This component is designed to replicate the size, shape, and color of the missing tooth for both aesthetic and functional purposes. The pontic transfers the biting forces normally handled by the natural tooth root.
The abutments are the anchors, typically requiring the adjacent natural teeth to be reduced in size to accommodate the receiving crowns. These supporting crowns bear the load of the entire bridge structure, making their connection to the natural tooth structure critical for longevity. In some designs, such as a Maryland bridge, the abutment may be metal or ceramic wings bonded to the back surface of the adjacent teeth rather than full crowns.
Material Categories and Composition
Dental bridges are manufactured using three primary material categories: metal alloys, ceramics, and composite resins. Metal alloys are chosen for their strength and resistance to fracture. These alloys may contain noble metals like gold and palladium, or be composed of base metals such as nickel and chromium.
Ceramic materials are favored for their ability to closely mimic the appearance and translucency of natural tooth enamel. Traditional options include feldspathic porcelain. Newer, high-strength ceramics include Zirconia and Alumina.
Composite resins, which are a mixture of plastic and fine glass or silica particles, are also used in bridge construction. These materials offer an affordable option that can be easily matched to existing tooth color. However, composite resins are less durable than metal or advanced ceramics and are more commonly used for temporary bridges or in less stress-bearing areas.
Performance and Placement of Bridge Materials
All-metal bridges, typically using gold or base metal alloys, offer the highest fracture resistance and are highly resistant to wear. Because they lack a natural tooth color, these restorations are usually reserved for posterior teeth where appearance is less of a concern.
Porcelain-Fused-to-Metal (PFM) bridges combine the strength of a metal substructure with a porcelain layer for a tooth-colored exterior. This combination provides structural support and acceptable aesthetics. A potential drawback of PFM is the possibility of a gray line becoming visible at the gumline over time as the gum tissue recedes, revealing the underlying metal margin.
All-ceramic bridges, particularly those made from Zirconia or lithium disilicate (E-max), are selected when aesthetics are the priority, such as for front teeth. Zirconia is a strong ceramic that can rival the durability of metal, making it suitable for both anterior and posterior applications. Other all-ceramic options achieve the highest level of natural appearance because they allow light to pass through them like natural enamel.
Longevity and Care Based on Material
The expected lifespan of a dental bridge is influenced by the chosen material and the patient’s habits. Metal bridges are known for their durability, often lasting two decades or more, but their hardness can lead to increased wear on opposing natural teeth. Ceramic bridges, while aesthetic, may be more susceptible to chipping or fracture if exposed to excessive biting forces or hard foods.
All-ceramic materials like porcelain are more prone to wear compared to PFM or all-metal restorations. Regular care is necessary regardless of the material to ensure long-term stability. This care includes using specialized tools, such as floss threaders or superfloss, to clean the space beneath the pontic, where plaque and debris accumulate.
Maintaining the health of the abutment teeth is important, as decay in these anchor teeth is a common cause of bridge failure. Patients with durable materials like Zirconia or metal may be advised to wear a night guard if they grind their teeth, protecting the opposing teeth and the restoration from undue stress.