Creating a crown or bridge is a multi-step process that requires careful planning and execution. Before a dentist can send cases to the lab for fabrication, they first need to prepare the teeth that will receive the restoration. This process involves removing a certain amount of tooth structure and shaping it in a specific way to ensure proper fit and function of the final restoration, as well as taking imprints for the lab to use as a guide.
How well a dentist prepares a tooth for a crown or bridge can greatly impact the success and longevity of the final restoration. In this detailed overview, we cover what dentists need to know to achieve optimal results in crown and bridge preparations.
To prepare a tooth for a crown, there are a few steps a dentist needs to follow. By following these steps, the dentist can make sure the final crown fits properly and functions well within the patient's mouth.
You should start by removing sufficient tooth structure to accommodate the crown while preserving as much of the healthy tooth structure as possible. This usually involves reducing the tooth’s height and width to create space for the crown material.
The type of crown determines the amount of reduction needed, but generally, there should be a minimum thickness of 1.5–2mm for adequate strength and retention. It’s important to note that not all teeth require the same amount of reduction. Anterior teeth may only need minimal preparation, while posterior teeth may require more extensive preparation due to their function in chewing and grinding food.
You'll also need to create a margin or "finish line" for the crown to sit on. The margin of a crown refers to the edge or border that connects the prepared tooth to the crown material. This area needs to be properly shaped and positioned to ensure a good fit and seal between the tooth and the crown and prevent bacteria from entering.
This margin should be smooth and even, with no undercuts or sharp edges that could cause irritation to the soft tissue. The type of margin used will depend on the material and design of the crown, as well as the location and condition of the tooth.
After preparing the tooth, take an accurate impression of it to serve as a guide for the lab in creating the final restoration. Use impression materials like alginate or polyvinyl siloxane (PVS) to capture the exact shape and size of the prepared tooth, as well as its surrounding teeth and gums. Make sure the impression is free of any bubbles or distortions that could affect the fit and accuracy of the final restoration.
In place of a traditional analog impression, some dentists now use digital scanners to take a virtual 3D image of the prepared tooth and its surrounding structures. This method offers more accuracy and efficiency in capturing the needed information and eliminating the need for messy impression materials. Digital impressions provide a 3D model of the preparation and can be quickly sent to the lab.
Preparing a tooth for a bridge involves many of the same steps as crown preparation, with a few additional considerations. Because a bridge is a multi-unit restoration, the preparation process may vary depending on the number of teeth involved and their location in the mouth. Be prepared for a slightly more time- and labor-intensive process compared to preparing for a crown restoration.
Begin by preparing the abutment teeth (the teeth adjacent to the gap) by reducing their height and width to allow space for the bridge. Ensure the preparations are parallel to each other to ensure proper fit and function.
In some cases, a dentist may need to reshape the abutment teeth if they're not strong enough to support the bridge. This may involve adding a core buildup or placing a post to provide additional support.
Next, take precise impressions of the prepared abutments and the edentulous space. You can use the traditional analog method for this and send the impressions to the lab, or use digital scanning technology for a more accurate and efficient process.
While waiting for the lab to fabricate the final bridge, you should provide a temporary bridge to maintain aesthetics and protect the prepared teeth.
You should provide detailed instructions and clear impressions or digital files to the dental lab. Specify the type of crown or bridge material, shade, and any special requirements. This will help the lab create a restoration that closely matches the natural teeth in shape, size, and color.
The lab will use the impressions or digital images to fabricate the bridge using either traditional hand waxing techniques or computer-aided design/computer-aided manufacturing (CAD/CAM) technology.
Once the crown or bridge has been fabricated by the lab, it’s time for placement. Before cementing or bonding the final restoration, you should ensure proper fit, occlusion (how the teeth come together), and aesthetics. Make any necessary adjustments before permanently placing the crown or bridge onto the prepared teeth.
It’s important to provide patients with post-operative care instructions and schedule follow-up appointments to monitor the success of the restoration and address any concerns. But assuming you’ve followed the proper steps for preparing and placing the crown or bridge, the outcome should be a functional, long-lasting restoration that restores the health and appearance of your patient’s mouth.
Knowing how to prepare for a crown or bridge placement is just one part of ensuring successful restorative treatment. Dentists should also take care to choose a lab partner that uses high-quality materials and skilled technicians to create custom-made, accurate restorations.
DDS Lab fabricates ceramic crown and bridge with precision and consistent quality to help dentists provide superior restorative care to their patients. If you want to learn more about our services, contact us today. And once you feel confident that we’re the right lab for your practice, you can submit a case for us to work on through our online lab portal.