Prostheses applied in dentistry are used to reconstruct losses occurring in the mouth, such as missing teeth, missing parts of teeth, and missing soft or hard structures in the jaw and palate. Prosthodontics is the dental specialty concerned with dental prostheses. Such prostheses are used to improve mastication, aesthetics, and assist with speech.
Dentures are fixed to teeth or dental implants with the help of dental adhesive or screws. Dentures used in partial or completely edentulous mouths are applied by utilizing friction against the parallel hard surfaces and undercuts of the teeth or dental implants, the formation of a vacuum utilizing mucus secretion, and using the surrounding muscles and the anatomical contours of the jaw to passively hold them in place.
Who is Prosthetic Dental Treatment Applied To?
Dental prostheses, can be applied to patients of all ages for functional, phonatory, and aesthetic purposes in individuals who have tissue loss in their teeth, or partial or total tooth loss in their mouth. At the same time, they are frequently used to replace the soft and hard tissues surrounding the teeth.
Prostheses made to replace teeth can be held in place by attaching them to teeth or dental implants, or passively retained via vacuum and by the surrounding muscles. Like other types of prostheses in the body, they can be permanently fixed or removable; fixed prostheses and removable prostheses are made in many variations.
What are the Prostheses Used in Prosthetic Dental Treatment?
In prosthetic dental treatment, 2 main methods are generally applied: "removable prosthesis" and "fixed prosthesis". Of these, the removable prosthesis is also divided into 2 sub-groups. We can list them as follows;
Fixed Prostheses: Particularly significant substance loss in teeth or partial tooth loss can be replaced with fixed prostheses.
Inlays and Onlays: These are restorations prepared on a model in a laboratory environment using materials such as composite or porcelain to replace substance loss in teeth, and bonded to the patient's teeth. They are often an alternative to direct dental fillings applied inside the mouth. While inlays do not include the upper parts of the teeth called cusps, cusps are included in the restoration in onlays. Since they are prepared in a laboratory environment, their contacts with adjacent teeth are very good, their durability is high, and they are aesthetic.
Porcelain laminate veneers (PLVs): The primary use of PLVs is to improve anterior aesthetics by altering tooth morphology and color. PLVs are the least invasive of dental restorations, typically involving the buccal surfaces of anterior teeth. If the underlying tooth color is acceptable, only minimal tooth reduction is sufficient to improve shape and color with a thin porcelain laminate produced in a dental laboratory. PLVs are the most commonly prescribed type of restoration.
However, it should be remembered that it is controversial to prepare vital healthy teeth for PLVs with very little aesthetic improvement purely for cosmetic reasons, especially if similar results can be achieved with less invasive protocols such as bleaching or composite resin fillings.
Crowns: This is a method used for extensive tooth loss. After the loss of substance in the tooth is replaced with a suitable method such as a filling, the teeth are circumferentially reduced just enough to create space for the crown material to be placed to protect the teeth. Crowns are prepared in a laboratory environment using a material suitable for the patient and cemented onto these reduced teeth. Crowns can also be applied for different reasons such as discoloration, fractures in teeth, and alignment of teeth located outside the dental arch. Different crown materials are used for these purposes. The most commonly used ones include feldspathic porcelain varieties, reinforced porcelains such as E-max, zirconium, metal-ceramics where metal and porcelain are used together, and reinforced composites.
Bridges: If there are a sufficient number of strong teeth that can be used as support in front of and behind the tooth gaps, bridge restorations can then be used to complete the missing tooth or teeth. By using the teeth located in front of and behind the gap, the prosthesis replacing the missing tooth can be suspended over this gap. Single tooth loss or multiple tooth loss can be completed with these bridges. It is a method that requires the root and surrounding tissue of the supporting teeth to be healthy.
Partial Prostheses: If the areas with tooth deficiency are numerous, the lengths of the tooth gaps are large, or if the tooth gaps are not bounded by any tooth, partial prostheses are utilized to eliminate these tooth deficiencies. These prostheses consist of a main framework placed on the teeth and components used to provide the retention of the prosthesis. Prosthesis retention can be provided by clasps called hooks placed on the teeth, as well as precision attachment parts that usually fit the key-lock system. The main framework extends over the edentulous spaces to provide maximum tissue support. The prosthesis is attached to some of the existing teeth with the aid of intermediary parts. In this type of prosthesis, some or all of the existing teeth are covered with a crown prosthesis. Patients can remove this prosthesis with very little force and clean it.
Complete Prostheses: In cases where all teeth are lost, teeth are placed on a base and the base is extended over the largest area compatible with the mouth anatomy. In this way, it is aimed to ensure the retention of the prosthesis by providing maximum contact between the base and the patient's gingiva. Many factors such as mouth anatomy, time of tooth loss, the amount of remaining bone and soft tissue, saliva, and support of surrounding muscles are effective in the success of such prostheses.
Implant-Supported Prostheses: Implants are titanium screws in the shape of a tooth root. These prostheses can be fixed or removable. They can be used instead of a single tooth, in partial tooth deficiencies, or in total edentulism cases. They can be completely implant-supported or supported by both implants and tissue. Their connection to implants can be made with the help of adhesive, screws, or abutments. Generally, by placing 4-8 implants in a single jaw, fixed implant-supported prostheses can be made, while tissue- and implant-supported prostheses over at least two implants can be made. Durable materials such as metal, porcelain, and zirconium are utilized in implant-supported prostheses.
Metal-Ceramics: Since porcelains are not very strong on their own, they are supported by a substructure. Metal has been used for this purpose for many years. It is quite durable. It is easily used for long bridges. To cover the gray color of the metal, a white substance called opaque is applied between it and the porcelain. Aesthetically satisfying results are achieved. The possibility of the gray color of the metal reflecting from the gingiva may cause aesthetic discomfort. It is not used in patients with metal allergies. The chipping or detachment of porcelain over the metal can lead to aesthetic problems.
Porcelain: Its main structure consists of clay. They are obtained by firing under vacuum at various degrees. They can be used for aesthetic purposes on substructures such as metal, zirconium, or E-max in crown and bridge making, or they can be used alone as crown, laminate, inlay-onlay materials. Porcelains are hard glass structures that give a lifelike appearance and do not discolor. They are also manufactured to be used as artificial teeth in removable prostheses.
E-Max: The areas where porcelains can be used alone are limited. E-maxes are porcelain structures reinforced with various methods. They are used in the making of crowns, short bridges, laminates, and inlays-onlays. Since they can be produced without a substructure, they are extremely aesthetic materials. Their gingival adaptation is very good. They adapt aesthetically very well to the natural teeth present in the patients' mouths. They are bonded with special adhesives. Color options are quite numerous.
Zirconium: Zirconium is actually the oxide form of the metal zirconium, which is also found in the periodic table. It is a white-colored material. This eliminates the problem of metal reflection from the gingiva, which can cause aesthetic problems in metal-ceramics. The biocompatibility of zirconium with body tissue is very good. They are used as a substructure material by applying porcelain on them. In recent years, since sufficient translucency has been achieved with additional substances added into them, they can be easily used alone as crown and bridge materials. Being a white material, it allows less reduction from the tooth structure. In patients with bruxism, they can be used alone since the risk of porcelain chipping is eliminated. It is also used as a substructure material in fixed prostheses on implants.
What are Maxillofacial Prostheses?
Jaw and facial defects are deficiencies occurring in the jaw and/or facial region either congenitally or due to later-developed causes such as trauma and cancer. They are classified as upper jaw defects (maxillary defects), lower jaw defects (mandibular defects), and facial defects. Defects seen in regions such as the eyes, nose, ears, and cheeks fall under facial defects. These defects can be in a single region or can be observed in multiple regions.
The treatment of jaw and facial defects can be performed both surgically and prosthetically. Both treatment methods have certain advantages and disadvantages compared to each other. The shape, size, and etiology of the defects are the main factors in deciding the treatment method. Surgical methods are generally preferred for small facial defects.
