Fixed Prosthesis

Monolithic Layered Zirconia

Over the years, restorative dentistry has witnessed significant advancements in materials used for full-coverage restorations, whether for a single unit or the classic roundhouse. The preferred choice for decades has overwhelmingly been the porcelain-fused-to-metal crown (PFM) in situations requiring full coverage. Monolithic Zirconia has emerged as a noteworthy alternative.
Zirconia, or zirconium dioxide (ZrO2), is a ceramic material derived from zirconium silicate (ZrSiO4). It exhibits mechanical properties similar to stainless steel, standing out as the most robust among ceramics in dentistry. Monolithic zirconia restorations at Indent Dental Laboratory, exclusively manufactured by CAD/CAM technology, have several advantages:

1. High flexural strength.
2. Requires a more conservative dental preparation, preserving natural tooth structure.
3. Great optical adaptability.
4. Minimizes wear on opposing teeth.
5. Exhibits satisfactory aesthetics.
6. Requires less laboratory time and fewer dental sessions.
7. Being monolithic, it avoids the complication of chipping.

Until a few years ago, the primary drawback was the low aesthetic performance due to the challenge of achieving satisfactory transparency. Recent modifications in composition, structure, and fabrication methods have yielded monolithic zirconia ceramics with superior translucency. However, this enhancement has come at the cost of reduced strength. Notably, the strength of monolithic zirconia restorations is inversely proportional to their translucency—the more translucent, the lower the strength.
It’s crucial to note that monolithic zirconia is a relatively new material, and scientific understanding regarding its properties, limitations, aesthetic evolution over time, resistance to low-temperature degradation, and overall clinical survival is still limited.

DID YOU KNOW?

Zircon Oxide was initially developed for space travel due to its high loading properties. However, its excellent mechanical properties and tooth-like colour have led to its adoption in dentistry.

MultiCOM Polymer Composite

MultiCOM Polymer Composite is a two-stage process where an aesthetic prosthesis is fixed over a polymer-based framework. This material is indicated for use in the mouth for a period of 2 to 5 years only.

What is SAPTeeth?

One of the most advanced material groups for these artificial teeth are called SAPTeethTM. These are a group of highly advanced polymers which are specially constructed to protect the bone, the implants and the natural tooth under the prosthesis. Based on research, it is concluded that ceramic, porcelain, Ni-Cr (metal) and titanium teeth exert stresses on the bone that are about 24 to 149 times more than the forces exerted by SAPTeethTM. This difference is largely down to the shock-absorbing ability of these polymers. Therefore, in patients with a weak bone structure or brittle bone, SAPTeethTM are recommended over conventional prostheses.

What makes SAPTeeth the best choice?

In case of breakage due to any reason including trauma, the repair of these composites is quite easy, and can be performed in the mouth itself. In cases of repeated breakage, only 10mm of either side of the breakage is remade. This ensures that the original strength is regained. In case of infection in the underlying tooth or implant, the whole bridge does not need to be removed, but instead, only the relevant part may be treated and consequently refurbished in a brief period of time at chairside itself. When there are habits like pan chewing, supari chewing, heavy bite or bruxism, the eating surface may wear off, but the re-layering can be done at only a fraction of the price and in very little time.

Advantages of MultiCOM:

1. Metal-Free with shock absorbability up to 30% of the normal load.
2. Two-stage technique, ensuring better and more stable repairs.
3. Superior in aesthetics and function when compared to other polymers.
4. Economical when compared to more advanced polymers.

Indications:
These Fixed Prostheses exhibit lower wear and tear compared to Resin, while still retaining the distinct advantage of reducing the load on underlying structures. They can be used as intermediate Fixed Prostheses under conditions such as heavy bite force, paan-supari habits, bruxism, clenching, etc. These Fixed Prostheses can be repaired, replaced, or upgraded as needed. The repair of such Fixed Prostheses is superior, as the framework provides protection to the inner structures.

Precious Alloys: Crown and Bridge

Precious metal alloys (or high noble alloys) are alloys that are predominantly comprising high noble metals such as gold, platinum, osmium, iridium, palladium, ruthenium, rhodium and silver. High Noble Alloys strictly maintain more than 40 wt% of gold (Au) and more than 60 wt% of noble metals in general. The majority of precious metal alloys in dentistry are used for indirect restorations such as inlays, onlays, crowns and bridges.

‘Full metal’ prosthetics is a common dental term describing restorations that are done without veneering porcelain for ceramic bonding. A ‘full gold’ crown implies a full metal crown with a high content of gold. Full gold restorations have been used in dentistry for a very long time, taking advantage of the excellent properties of alloys, and in turn have become the standard by which most other restorative systems are judged.

High noble alloys can be divided into three groups:
– Au-Pt – commonly used for both, full metal and ceramo-metal applications.
– Au-Pd – widely used as a high noble dental casting alloy for ceramo-metal restorations.
– Au-Ag-Cu – not typically used for ceramo-metal bonding as the temperature of the solidus is too low for porcelain fusion. Therefore, these alloys have been used since many years for full metal applications.

Mechanical Properties:

Advantages:

1. Superior Strength – Due to their 100% metal construction, there’s no type of crown that’s stronger than an all-metal one. Failure of the restoration due to breaking is an extremely rare occurrence.
2. Great longevity – Due to its single-component construction along with the great strength and durability characteristics it possesses, no other type of dental restoration provides a more lasting service than an all-metal one.
3. They offer good biocompatibility.
4. Cause minimal wear to opposing teeth.
5. Allergies due to high noble alloys are rare.
6. Because of being very pliant and workable, high noble alloys provide a superior fit.

Provisional Fixed Restorations

A provisional fixed prosthesis, as defined, is designed to enhance aesthetics, stabilization, and/or function for a limited period, after which it requires replacement with a definitive prosthesis. Often used to assess the therapeutic effectiveness of a specific treatment plan, these prostheses must fulfil biological, mechanical, and aesthetic requirements, aiming to mimic the properties of natural teeth and surrounding structures. The significance of interim treatment with provisional restorations becomes crucial in full mouth reconstruction cases, where multiple teeth are prepared. Provisional restorations are typically used for relatively extended periods (6-12 weeks) to monitor patient comfort and satisfaction and facilitate necessary adjustments.

Provisional material selection is based on how their mechanical, physical, and handling properties meet specific requirements for a clinical case. Factors such as biocompatibility and complications from intraoral use, such as chemical injury from monomer residue or thermal injury from exothermic polymerization reactions, also need consideration.

Uses of Provisional Fixed Restorations include:

1. Protecting pulpal and periodontal health.
2. Promoting guided tissue healing for an acceptable emergence profile.
3. Evaluating hygiene procedures.
4. Preventing migration of abutment teeth.
5. Providing an adequate occlusal scheme.
6. Evaluating maxilla-mandibular relationships.
7. Protecting and resetting joint function.
8. Cost-effectiveness.

Provisional Fixed Restorations come in three main types:

1. Preformed Custom Crowns (tooth-shaped shells of plastic, cellulose acetate, or metal).
2. Customized Resin Restorations.
3. Acrylic Resins (available as powder and liquid).

Techniques Used:

1. Indirect Technique (fabricating the restoration outside the patient’s mouth, typically in the laboratory).
2. Indirect-Direct Technique (preforming the bulk external surface while custom preparing the internal tissue surface inside the patient’s mouth; the laboratory provides the wax up and impression for temporary creation).
3. Direct Technique (preparing the entire restoration and its soft tissue features inside the patient’s mouth).

Precise knowledge of available materials and techniques enables clinicians to reline, modify, or repair these restorations as needed. At Indent Dental Laboratory, we serve patients and dentists by providing excellent, aesthetic provisional for temporary to intermediate restorations.