Crowns & Bridges

Overview

Crowns and bridges are among the most frequently performed restorations in prosthodontics, and for good reason: they solve a wide variety of clinical problems with predictable, long-lasting results. A crown restores a single damaged tooth. A bridge replaces one or more missing teeth by spanning the gap and anchoring to the teeth on either side. Both are cemented permanently in place and function like natural teeth.

Dr. Rasmussen approaches every crown and bridge case with the same rigor he applies to complex reconstructions. Margins are placed precisely, impressions capture every detail of the preparation, and the final restoration is evaluated against strict criteria for fit, contour, occlusion, and aesthetics before it is cemented. The difference between a crown that lasts five years and one that lasts twenty often comes down to how carefully these details are managed.

Dental Crowns

A dental crown is a full-coverage restoration that encases the entire visible portion of a tooth above the gum line. Crowns are indicated when a tooth has lost so much structure to decay, fracture, or previous dental work that a filling or onlay can no longer provide adequate strength. They are also placed over teeth that have undergone root canal therapy, which removes the nerve and blood supply and leaves the tooth more brittle and susceptible to fracture.

The tooth is reshaped to create a uniform reduction of one to two millimeters on all surfaces, creating space for the crown material while preserving as much healthy tooth structure as possible. A digital scan or conventional impression captures the prepared tooth and the surrounding teeth, and the data is sent to the dental laboratory where the crown is fabricated. A provisional crown protects the tooth during the fabrication period, which typically runs ten to fourteen business days.

At the delivery appointment, the provisional is removed and the permanent crown is tried in. Dr. Rasmussen checks the marginal fit under magnification, verifies that the contacts with adjacent teeth are appropriate, and adjusts the bite so that forces are distributed evenly. The crown is then cemented with a permanent dental cement.

Crown Materials

Zirconia. A high-strength ceramic that has become the workhorse material for posterior crowns. Modern multilayer zirconia blanks offer a gradient of translucency from the cervical area to the incisal edge, producing a natural appearance without sacrificing strength. Zirconia is milled from a solid block using CAD/CAM technology and sintered at high temperature to reach its full density. It is extremely fracture-resistant and well-tolerated by gum tissue.

Lithium disilicate (e.max). A glass ceramic with exceptional translucency, favored for anterior crowns where aesthetics are paramount. It is not as strong as zirconia under heavy occlusal loads, so its use on molars depends on the patient's bite forces and habits. Lithium disilicate can be pressed or milled and is easily customized with surface staining and glazing.

Porcelain-fused-to-metal (PFM). A metal substructure veneered with layered porcelain. PFMs were the standard for decades and still have a role in certain clinical situations, particularly long-span bridges where the rigidity of a metal framework is beneficial. The trade-off is a slightly less translucent appearance and the possibility of a dark line at the gum margin if the tissue recedes over time.

Full gold. Gold alloy crowns remain the most conservative preparation and the most forgiving material in terms of fit. They are rarely used in visible areas, but for second molars and teeth that are not seen when smiling, a gold crown can provide decades of trouble-free service with minimal tooth reduction.

Dental Bridges

A dental bridge fills the space left by one or more missing teeth. The classic fixed bridge consists of crowns on the teeth adjacent to the gap (called abutment teeth) connected to one or more artificial teeth (called pontics) that fill the space. The entire unit is fabricated as a single piece and cemented onto the abutment teeth.

A three-unit bridge -- two abutments and one pontic -- is the most common configuration, used when a single tooth is missing. Longer-span bridges replacing two or three consecutive teeth are feasible when the abutment teeth are structurally sound and well-supported by bone. Dr. Rasmussen evaluates the periodontal health, root length, and bone support of the abutment teeth before recommending a bridge, because these teeth will carry the additional load of the missing tooth or teeth.

Types of Bridges

Traditional fixed bridge. The most common type, with full crowns on both abutment teeth connected to one or more pontics. This design provides maximum stability and is suitable for areas that bear significant chewing forces.

Cantilever bridge. Supported by an abutment on only one side of the gap. This design is used in specific situations where only one adjacent tooth is available or suitable for preparation, and where the forces on the pontic will be manageable. It is most often used in the anterior region where bite forces are lower.

Maryland bridge (resin-bonded bridge). A pontic with thin metal or ceramic wings that are bonded to the back surfaces of the adjacent teeth. This design requires minimal or no tooth preparation, making it the most conservative bridge option. It is typically used as a long-term provisional or in situations where the adjacent teeth are healthy and the patient wants to avoid preparing them for full crowns.

Bridge vs. Implant

In situations where a traditional bridge would require cutting into healthy, unrestored teeth, a dental implant is often a better alternative. An implant stands independently in bone and does not involve the adjacent teeth at all. Dr. Rasmussen will discuss both options with you and explain the trade-offs in terms of longevity, cost, and tooth conservation so you can make an informed decision.

The Process

Treatment begins with a clinical examination and radiographs to assess the health of the tooth and its supporting structures. At the preparation appointment, the tooth is anesthetized and reshaped. Any decay or defective filling material is removed first, and if the remaining tooth structure is insufficient to support a crown on its own, a core build-up is placed using a bonded composite material to recreate the missing anatomy.

A digital impression is taken using an intraoral scanner, eliminating the need for conventional impression trays and materials in most cases. The scan data, along with a shade prescription and photographs, is transmitted electronically to the laboratory. A provisional crown or bridge is fabricated chairside and cemented with temporary cement to protect the teeth during the waiting period.

The final crown or bridge is delivered at the next appointment. After a thorough evaluation of fit, function, and appearance, it is permanently cemented. Dr. Rasmussen will review home care instructions specific to your restoration, including how to floss under a bridge pontic using a floss threader or interdental brush.

When You Might Need a Crown or Bridge

A tooth that has fractured below the cusp tip usually cannot be restored with a filling alone -- the remaining walls are too thin and will flex under chewing forces, eventually cracking further. A crown binds the tooth together and distributes forces evenly.

Teeth with large, aging amalgam or composite fillings are another frequent indication. Over time, these fillings can develop microleakage at the margins, allowing bacteria to penetrate and cause recurrent decay underneath. If the filling occupies more than half the width of the tooth, a crown provides better long-term protection than replacing the filling with a larger one.

After root canal therapy, the treated tooth loses its internal moisture and becomes more brittle. A crown placed over a root-canal-treated molar or premolar significantly reduces the risk of a catastrophic vertical root fracture.

Missing teeth that are not replaced allow the adjacent teeth to drift and tilt into the empty space, and the opposing tooth may over-erupt. These shifts create bite interferences, food traps, and periodontal problems. A bridge or implant-supported crown restores the space and keeps the surrounding teeth in their proper positions.