Dental Crowns and Bridges

When a tooth is significantly damaged or crooked, but the root is good and no inflammation is detected, it can be preserved and covered with a crown. The crown protects the tooth and addresses functional and aesthetic issues. Crowns and bridges can perfectly mimic real teeth, making it difficult even for trained eyes to distinguish between original and artificial teeth. Crowns and bridges are mainly made from metal-fused ceramics or zirconium.

In case of tooth loss, following implantation, the crown is fixed to the implant using a passing screw. This is known as an implant crown.

A bridge is used to replace one or more missing teeth instead of implants. A bridge always consists of at least three parts and spans the gap by being fixed to the adjacent teeth, which act as pillars, or similarly to two or more implants. In this case, it is referred to as an implant-supported bridge.

The elements of the bridge are also crowns, and almost all crowns and bridges are made of metal with ceramic lining, full ceramics, or zirconium.

Metal-Ceramic Crown

The frame of metal-ceramic crowns is made from hypoallergenic, nickel-free metal, covered with ceramic. Characteristics:

• Good price
• Very strong and durable, but not ideal for molars due to extreme chewing pressure
• Less aesthetic due to greyish gum margins

Laser-Sintered Metal-Ceramic Crown

An advanced version of the classic metal-ceramic crown, differing in its manufacturing method. Traditional metal casting methods have been replaced by laser sintering. A digital machine builds the bridge frame layer by layer using a laser beam, reducing or nearly eliminating the possibility of errors. Characteristics:

• Cost-effective
• More precise and higher quality compared to traditional metal-ceramic crowns

Zirconium Crown

Made from zirconium oxide, these crowns have a completely metal-free frame. Characteristics:

• Natural appearance, perfectly mimicking real teeth
• Chemically resistant and high bending strength, making them stronger than metal-ceramic frames, leading to a longer lifespan as they don't break or crack
• The gum can grow around it, reducing the risk of gum recession or inflammation over time
• Hypoallergenic
• Made using CAD/CAM computer design and milling technology for greater precision
• Ideal for both front and molar teeth
• High cost-to-value ratio

Pressed Ceramic Crown

A metal-free, full ceramic version known as the pressed ceramic crown. Characteristics:

• No frame, made entirely from ceramic, offering superior aesthetics and translucency, hence mainly used for front teeth
• Light easily passes through the porcelain layers, providing a very natural look
• Perfectly replicates the color of natural teeth
• Precise fit thanks to CAD/CAM computer technology
• Metal-free and tissue-friendly
• Mainly used for single crowns and front regions, not suitable for long bridges and molars

Steps in Making Crowns and Bridges

Steps for Making a Crown:

1. The dentist applies local anesthesia around the tooth that will hold the crown.
2. The tooth is then precisely shaped by grinding, ensuring the ground tooth and crown fit exactly.
3. An impression is taken of the surrounding teeth and the prepared tooth stump.
4. A temporary crown is placed until the final crown is ready.
5. A framework trial is conducted, followed by a raw trial to check the color, shape, and fit.
6. After a few days, the final crown is made based on the previous impression.
7. The dentist fixes the final crown onto the ground tooth with special dental cement.

Combined Dental Prosthesis

Removable prostheses are necessary when there aren't enough pillars to anchor a fixed prosthesis (bridge). The pillar can be a tooth, a root with a post, or an implant (artificial root). Although the need for removable prostheses has decreased with the advancement of implants, economic reasons or bone resorption in old age without surgical intervention often make such prostheses the only option. Unfortunately, these always involve some movement during use. The degree of movement depends on anatomical conditions, jaw relationships, remaining teeth's shape and location, anchoring method, potential pathological changes, usage, bad habits, and the condition of the opposing teeth. Factors reducing stability include excessive chewing force and certain diseases (e.g., xerostomia, epilepsy, Parkinson's disease, psychological and neurological disorders, medications affecting saliva production). Partial removable prostheses always contain a metal framework, typically a special dental alloy, so it’s important to inform your doctor about any metal or acrylate allergies.

Removable prostheses can be full dentures without anchoring or partially removable prostheses connected to teeth or implants, further classified based on the anchoring method.

Clasp Retention:

The simplest and cheapest method, where the clasp arm encircles a tooth or a crown made for clasp holding. This puts stress on natural teeth, risking wear and breakage, but placing clasp-holding crowns can mitigate this risk. The advantage is that if a tooth is lost, it can be replaced without making a new prosthesis.

Slide and Ball Retention:

Used when the front teeth are present but the back teeth are missing. A fixed bridge is made for the front teeth, with a slide or ball at each end for the removable part to attach to, providing more stability than clasps. However, this requires grinding down the remaining teeth and joining them into at least pairs, making it unsuitable for weak, filled, root-treated, or capped teeth beyond a certain stage of periodontal disease. Consequently, costs are higher, but the hidden retention provides stability without visible attachments.

Full Denture (Prosthesis)

Thanks to preventive measures, fewer people are completely toothless today, though full dentures are still used, sometimes temporarily. It's essential to know that a good denture relies on the patient's active cooperation, willingness, adjustment process, and following medical instructions, which can take weeks or months. Dentures are held in place by friction and adhesion.

Problems:

• Initially, a slightly loose denture will adapt over time as facial and tongue muscles and the mucous membrane help hold it in place.
• Even well-made full dentures can lift off the mucous membrane unexpectedly, like during a sneeze.
• Frequent breakage of a removable prosthesis can occur if the denture strains and breaks over bony areas. Strong chewers might need a thin metal-based prosthesis to prevent breakage.
• Difficulty in adjusting to a full removable prosthesis or adverse conditions (abnormal lip movement, biting issues, unfavorable anatomy) can lead to instability, for which denture adhesives can be used, especially for public figures.
• Mild mucosal irritation and increased saliva production are common initially but should subside with time.
• Persistent issues may require multiple adjustments, which are performed free of charge.
• Initially, finely chopped foods should be consumed, ensuring to chew on both sides to prevent the denture from tipping and injuring the gum. This becomes automatic over time.
• Especially after recent extractions, bone and gum resorption may require denture relining to restore stability.
• For upper dentures, covering most of the palate can make adjustment difficult and affect thermal and taste sensations.

Using a Denture

Contrary to popular belief, dentures do not need to be removed at night. This was necessary only with old rubber or poorly polymerized plastic dentures. Modern dentures should be worn continuously and removed only for cleaning. Proper cleaning is essential for your health and the prosthesis’s condition, and all new denture wearers receive a guide with supplementary oral and written information. Continuous wear aids adjustment, while intermittent removal can reduce suction and reset the adaptation process.