Discolored teeth are often the result of root canal treatment. Although porcelain fused to metal restorations can cover discolored tooth, the metal coping causes gray line along the margin too show up. This is because the metal coping does not allow light to pass through the tooth tissue.

Theses dark rims are eliminated in all porcelain restorations especially lithium disilicate ceramic restorations. IPS e.max lithium disilicate ceramics have both high strength and excellent esthetics. The translucency of this porcelain allows the light pass through the restoration to the tooth, thus gingival black margin (which is common among metal ceramic restorations) is avoided.

IPS e.max lithium disilicate results in life like esthetic results. The type of material used can be selected in an optimum degree of opacity and transluscency inline with the shade of the remaining tooth tissue. Lithium disilicate ceramics offers convenient combination of press and layering materials.

Familiarity to basic principles of natural oral esthetics is needed to create beautiful restorations.

Examine the bone density at the fixture sites and monitor marginal bone loss. With a good parallel radiograph, the marginal bone loss is measured using the fixture threads as reference.

The marginal bone loss can range from 1.0 to 1.5 mm vertically in the first year. The fit between the abutment and fixture is also checked. Fixture fractures should also be checked. After the first year, estimated bone loss per year is less than 0.05 – 0.1 mm and offers a predictable long term prognosis.

Radiographs are made at the time of abutment connection and restoration insertion. Follow up radiographs are made at 1, 3, 5, 7, 10, 15 and 20 year recall. After 20 year recall the radiographs are made every 5 years.

A radiograph showing three dental implants.

Indications for use of screws in Prosthetic Dentistry:
1. The main indications are the connections of abutments and the construction of functional dental prosthesis.
2. Where a conventional fixed dental prosthesis cannot be constructed, screws can be employed to connect parts of the denture to in the mouth, thereby forming a functional fixed dental prosthesis.
3. Screw assemblies may be used to allow the prosthesis to be removed by the dentist. This can be useful in planning ahead.
4. Because dentist can remove the dental prosthesis, it is possible for him to examine the area underneath the pontics to prevent inflammation. Repairs are also simplified.

Upper lateral incisor joined to implant via Screwed Joint.

It is common to see patients with loose or dislodged jacket crowns or fixed dentures. The results of a crown becoming loose could be problematic, including the danger of ingestion and inhalation.

Patients with mobile jacket crowns usually feel dental hypersensitivity, adverse appearance as well as the worry of sudden dislodgement and ingestion of the loose dental crown. Other patients will also have gingivitis and periodontal problems.

There is also a possible loss of positional stability of the abutment tooth, potentially leading to over eruption of the said tooth or the opposing tooth.

A strong resin cement like Panavia should be considered in the case of a non retentive preparation on the tooth is discovered. Thorough examination of the occlusion should be done.

Strong resin cement like Panavia should be used in the case of a non retentive tooth preparation.

Types of ceramic dental crowns that are commonly available:
1. Metal ceramic
2. High-strength cores
3. Pressed-glass ceramics
4. Milled porcelain
5. Cappilary technique
6. CAD CAM

Metal ceramic crowns are the conventional and most commonly used technique. It utilizes the bond between porcelain and metal that is achieved at high temperatures. Enough space is needed from tooth prep for the opaque porcelain, dentin and enamel porcelain to create the appearance.

High strength core crown consists of 2 layers. The dental crown’s strength is derived from the inner core made from Inceram, and overlaid with conventional porcelains to improve the esthetics. Inceram is a glass and alumina material.

Fine alumina powder is applied to an absorbent refractory die and any residual pores are filled with molten glass to produce a dense, crystalline core structure. The core has high strength and elastic modulud. The high content of alumina makes it resistant to acids making adhesive bonding difficult.

Conventional metal ceramic dental crowns