Dental prosthetics (fabrication of artificial teeth) is performed when teeth are missing or treatment with fillings is no longer sufficient to restore chewing, aesthetics and clear pronunciation of sounds (phonetics) acceptable to the patient. Dental prostheses are manufactured from alloys of noble and base metals, various types of ceramics (porcelain), medical plastic.

Prosthetics is a final stage in dental treatment performed after surgical, periodontological, therapeutic or orthodontic treatment ensuring the stability and longevity of the results of the treatment performed. It is one of the most complicated areas in dentistry requiring a detailed preparatory treatment: planning of other professionals’ work, careful selection of teeth for prosthetics and most importantly a far-sighted forecast, i.e. how long will it last?

Types of dental protheses

Kiekvienam pacientui protezai parenkami individualiai, pagal esamą burnos būklę ir pageidavimus bei Dental prostheses are selected individually for each patient, depending on the current oral health condition, wishes and possibilities. Two major groups of dental protheses are distinguished based on whether they are removed from the mouth or not:

• Fixed dental protheses (laminates, inlays, onlays, crowns, bridge dentures);

• Removable dental protheses (dentures with metal framework aka “bugels” and veneers).

Removable dental protheses have to be constantly taken out from the mouth in order to clean food from them. They are most difficult to get used to due to a larger size, lack of stability in the mouth, a distinct feeling of a foreign body, increased secretion of saliva, likely nausea and disturbed pronunciation of sounds. It is difficult to chew food with removable dental protheses because they press gums. These dental protheses are the most inconvenient, yet they are fabricated faster and are most economical.

Fixed dental protheses are cemented on teeth with special cement. Patients do not feel any discomfort and inconveniences differently from removable dental protheses because there is no need to take them out. Their fabrication takes longer and is more complicated; therefore, they are more expensive.

The material which will be used for fabricating these dental protheses depends on the type of prothesis, the desired aesthetic result and financial means. Temporary crowns (used until permanent crowns are fabricated), removable dental protheses (full, partial veneers and dentures with metal framework) are made of medical-grade plastic.

Major advantages of this material: aesthetic enough, easy to repair, economical. Its disadvantages: fragility, i.e., it breaks, wears off faster than natural teeth, changeability, i.e., change in colour, accumulates more plague and bad odours, irritation, i.e., may cause gingival inflammation or even allergy.

Individual crowns and bridge dentures can be fabricated from pure metal. Alloys of noble metals (gold, platinum, palladium) or base metals (chromium and cobalt, chromium and nickel, titanium) can be used for this purpose. All-metal dental protheses have been seldom fabricated recently because they do not look good. Yet they have several advantages: the tooth is subjected to little shaving, the prothesis is the firmest and the most long-lasting, the prothesis is more economical than porcelain-fused-to-metal dental protheses. Normally, porcelain-fused-to-metal crowns or bridge dentures are used. Ceramics (porcelain) is ‘baked’ on a cast metal frame (alloys of noble and base metals can be used) in a special furnace. Dental protheses manufactured in this way are aesthetical and firm enough.

Disadvantages: cracking. i.e., ceramic finish may fracture, price, i.e., more expensive.

Pure ceramics is used for fabrication of crowns, inlays, onlays, and laminates. All-ceramic crowns can be used for both incisors and lateral teeth.

Advantages: the highest degree of aesthetics obtained, great compatibility with natural teeth, very strong adherence to dental tissues by using special cements. Disadvantages: occasional cracks of ceramics, restorations are most expensive.

Fixed dental protheses

Dental laminates

Where only the front surface is affected, teeth may be restored by means of laminates (veneers). They are thin all-ceramic shells which are bonded on the front surface of teeth by means of special cements. It is a highly aesthetical and minimally invasive method of treatment. As all ceramic dental protheses, laminates must be used properly because they may fracture or come off.

Dental inlays and onlays

Where much of dental tissue is lost due to decay or other causes, it may be restored by means of large fillings. It is a fast and economical method. However, a higher-quality and longer-lasting solution is the use of micro prostheses, i.e. inlays and onlays. Inlays and onlays are firm fillings made of alloys of ceramics or gold in the laboratories fabricating dental protheses.

Insufficient oral care, poor diet and other causes lead to teeth wear and sometimes even their loss. Dental prosthetics can be the remedy in such cases. Dental prosthetics is the restoration of lost teeth and tooth tissues using special materials. Teeth can be replaced with micro- or fixed prostheses. It is a misconception that prosthetics involves shaving the teeth and placing a crown. Such drastic methods are outdated and no longer used in modern dentistry.

Micro-prosthetics is a treatment method that alters the shape, colour and anatomical structure of a tooth without shaving the healthy tooth tissues and adjacent teeth. Compared to large fillings, micro-prostheses wear less, which makes them a longer-lasting solution.

Micro-prosthetics is a meticulous procedure that restores only the area that the patient has lost. This way, the natural tooth tissue is preserved. In micro-prosthetics with laminates, metal-free ceramics is used to restore extremely natural-looking teeth. Laminates are ultra-thin plates that are cemented to the tooth surface and provide excellent functional and aesthetic benefits. The surface of the restorations is smooth, which prevents plaque build-up and discolouration. Dental laminates can be used to restore ten teeth in the upper jaw and ten teeth in the lower jaw. If the teeth are very badly damaged, this treatment is not recommended.

Types of micro-protheses:

• Inlays;
• Onlays;
• Crowns;
• Laminates.

Micro-prosthetics restores:

• Worn and shortened teeth;
• Discoloured teeth;
• Crooked, chipped teeth.

Benefits of micro-prostheses:

• Durability;
• Precision;
• Fracture resistance;
• Maximum preservation of healthy tooth tissues;
• Exceptional aesthetics.

Various types of ceramics are widely used in dental prosthetics. One of them is zirconium oxide ceramics. Currently, it is the strongest white material used in dentistry which is characterised by good aesthetic properties and excellent biocompatibility.

Zirconium is a metal represented by the symbol Zr in the periodic table of elements and located next to titanium (Ti). It belongs to the titanium metal family (titanium, zirconium, hafnium). It is not found in its pure form in nature. It is extracted from the minerals zircon (ZrSiO4) and baddeleyite (ZrO8). Most of these minerals, about 80%, are mined in Australia, South Africa and the USA. It is also found in Brazil, Russia and China. Baddeleyite contains particularly high levels of zirconium oxide but is quite rare and is mainly found in Brazil and Florida (USA). Zirconium ceramics are obtained through the Kroll metallurgical process. At the end of the process, white zirconium oxide powder is obtained (which is no longer a metal, but a ceramic). Zirconium oxide is used in various fields: in the manufacture of aircraft, engines, paints, electronics, etc. In jewellery, it is used to make artificial diamonds. Various metal alloys (chromium-cobalt, nickel-chromium, gold-platinum-palladium, etc.) have long been used in the manufacture of dental prostheses.

Dental prostheses in the mouth are in constant contact with saliva and are exposed to acids and temperature changes. This leads to corrosion, i.e. the decay of metals, and the ions of these metals enter the digestive system. Once in the human body, they can form various compounds and influence biochemical processes. This is particularly emphasised in homeopathy. Therefore, when performing dental prosthetics, it is recommended to avoid using different types of metals in the mouth. Zirconium, like titanium, from which dental implants are made, is a highly biocompatible and corrosion-resistant material. Zirconium oxide ceramics are particularly suitable for people with allergies and those looking for healthier alternatives.

Complex milling machines mill dental prostheses from zirconium oxide which are then subjected to high temperatures and become very strong. Zirconium oxide products have a fracture resistance of up to 1,500 MPa and are at least three times stronger than prostheses made from other types of ceramics.

Dental prostheses can be manufactured using only zirconium oxide or by coating it with a more transparent, more aesthetic but also weaker type of ceramic (feldspar or glass ceramic).

Natural teeth are loose in the bone because they are surrounded by ligaments that act as shock absorbers. Dental implants fuse directly with the bone and are almost immobile, prostheses made of weaker ceramics (e.g. metal ceramics) are therefore more likely to break. Such complications are extremely rare with zirconium oxide crowns. Zirconium oxide ceramics are also a more practical choice for fabricating dentures when people grind their teeth due to stress.

Since no metal prosthesis framework is used (as in the case of metal-ceramic prostheses), zirconium oxide ceramics allow more light to pass through, depending on their thickness. This makes artificial teeth look much more natural. With the right thickness, zirconium oxide crowns perfectly mask even very dark teeth or metal pins.

Dental prosthetics has long changed the perception we have of it where a tooth is shaved down and a crown is placed on top. With the daily advancement of dental treatment technologies, methods of preserving and restoring teeth have changed beyond recognition. Thanks to these advances, it is now possible to create a perfect smile with minimal intervention.

According to dentist Rūta Zykutė, modern least invasive dental prosthetics techniques help to preserve as much natural tissue as possible, which means that there is no need to be concerned about pain, tooth shaving or long healing periods.

With memories of childhood visits to the dentist fresh in their minds, people are still reluctant to make an appointment. How have dental techniques changed over the past twenty years?

In the 21^st century, dentistry is all about least invasive techniques. To this end, microscopic drills and special ultrasonic instruments are used, and the dentist works with image magnification devices (microscopes, telescopic glasses). Only damaged tissue is removed preserving as much of the healthy tissue as possible. Nowadays, dental clinics can offer patients the most modern restorative materials which have replaced the old generation of fillings. By combining the latest advances in technology and materials, we can provide patients with a perfect smile through micro-prosthetics.

Should one be scared of micro-prosthetics?

I would like to point out that the word “prosthesis” originates from Greek (pro(s)thesis: addition, connection; micro: small) and means replacing lost tissue or a part of it with some kind of artificial material that repairs functional and cosmetic defects. Many people believe that prosthodontists should only be consulted when a tooth is lost or when only the root remains, i.e. when the crown of the tooth is completely broken. However, any restoration in your mouth is called a prosthesis or micro-prosthesis depending on its size. A filling is therefore also a prosthesis which is usually made of a composite material. It has long been thought that in the course of prosthetics, the dentist shaves off a lot of tooth tissue and covers it with a crown. This belief is wrong, and the word “prosthesis” should not be feared because, with the rapid advancement in dentistry and modern technologies, dentists are able to restore damaged tooth tissue using least invasive methods.

This is an excellent alternative to dental crowns and a more reliable option than aesthetic fillings, as glass-ceramic laminates bond perfectly with healthy tooth tissue, do not accumulate plaque, which reduces the development of secondary decay, and are less prone to wear.

When should one choose this method of tooth restoration?

If a tooth is decayed, chipped, worn down or a large or medium-sized filling has fallen out and there is little healthy hard tooth tissue left, we can restore the lost function and anatomy with the help of micro-prosthetics by making onlays, inlays or laminates. All of these structures are cemented onto the surface of the tooth with minimal shaving. This type of restoration is a new approach to tooth restoration and longevity.

With age, teeth wear down and their surfaces erode, causing changes in the bite, which becomes irregular and sunken, and this further promotes tooth wear as the enamel layer erodes and the sensitive dentine is exposed. When replacing molars with micro-prostheses, the entire anatomical structure of the tooth is restored, including the grooves and cusps, which are very important for high-quality chewing and proper bite. This treatment method allows the lost tooth structure to be restored without damaging the remaining healthy tooth tissue or affecting the adjacent teeth. These restorations, i.e. micro-prostheses, are fabricated in a laboratory from aesthetic and extremely strong glass ceramics. Their resistance is 400 MPa.

When should one choose inlays/onlays, and when should one choose laminates?

Inlays and onlays are tooth restorations designed to restore the surface or part of a side tooth and protect the remaining weak structures of the tooth from possible decay. Laminates are used to restore defects in the front teeth. These are micro-prostheses that are used to precisely restore the shape, colour and anatomical structure of the tooth.

Can laminates be used to create a beautiful smile?

With laminates, it is definitely possible to create a perfect smile. By individually selecting the colour and shape of the teeth, it is possible to restore all the natural structures of the teeth. For patients who are dissatisfied with the shape or position of their teeth, who want to improve or restore their own teeth that have changed colour or started to decay, or who are unhappy with wide gaps between their teeth, or who want to remove the effects of dental trauma, to repair cracks, renew old restorations, or simply want a “Hollywood” smile, tooth-friendly, least invasive, aesthetic prosthetics with laminates can help achieve the desired result.

Does restoration with laminates require extensive shaving of the natural tooth structure?

Laminates are extremely thin (0.3 to 0.5 mm thick) glass-ceramic plates that absorb, reflect and transmit light in the same way as natural teeth. This method of tooth restoration is extremely gentle on tooth tissue. If a tooth is damaged by decay or an old infected filling, only the decayed tissue or old filling is removed, and sometimes the tooth does not even need to be prepared with a drill.

This is an excellent alternative to dental crowns and a more reliable option than aesthetic fillings as glass-ceramic laminates bond perfectly with healthy tooth tissue, do not accumulate plaque, which reduces the development of secondary decay, and are less prone to wear. Their composition is very similar to real tooth enamel, so neither their shine nor colour changes. These laminates are well tolerated by the body, and soft tissues, gums and papillae, adhere perfectly to the surface of the natural tooth.

Is tooth restoration with laminates a painful treatment?

Both the preparation of the tooth and the application of the laminates can be performed under local anaesthesia. There is no need to feel anxious, instead, focus on the excellent results and the desire to smile again.

If a tooth is decayed, chipped, worn down, or has a large or medium-sized filling and there is little healthy hard tissue left, we can restore the lost function and anatomy with micro-prosthetics by making onlays, inlays or laminates.

Is it possible to restore front teeth with glass-ceramic micro-prostheses if they were previously covered with old metal-ceramic prostheses?

Only after removing the old restorations can the dentist assess the colour and condition of the tooth tissue underneath. Sometimes, after certain treatments, such as intra-canal tooth root bleaching, it is possible to restore these teeth with metal-free ceramic micro-prostheses.

How many teeth can be restored during one appointment?

Depending on individual wishes and needs, micro-prosthetics can be used to restore a single tooth or all upper or lower teeth, and the duration of treatment depends on each individual case.

Is micro-prosthetics with laminates, onlays and inlays expensive?

These high-quality micro-prostheses require a lot of consistent preparation and meticulous work, it is therefore very important to discuss the cost of treatment and your expectations with your dentist before starting treatment. In any case, this is not a low-cost service but rather an investment in your beauty and health for many years to come.