The device implants
Not so long ago, low rates of engraftment, not exceeding 60%, deterred patients from prosthetics on implants. This was due to the imperfection of the first generation systems and technical flaws. Today, the models of leading companies are entirely devoid of previous flaws and in 95% of cases guarantee osseointegration. Conceptually, the system is designed to easily change the abutment and prosthesis if necessary.
A collapsible cylindrical metal pin for installation in the jaw is made in the form of:
- a self-tapping screw;
- smooth one-piece shaft with a textured surface;
- perforated with a hole diameter of 0.5-3.0 mm.
The upper part is made in the form of a kind of cap for the abutment. The adapter acts as a mediator between the maxillary and periosteal parts.
Many types of implants have adapters in the form of hexagons with a taper in the range of 20-40 °. In critical atrophy, they are placed in the bone at an angle of 10 ° – 20 °. Manufacturers apply to two-component products:
- a dummy screw;
- shaper of gingival contours;
- related elements – tips, springs, shock absorbers in the form of rings to reduce chewing load.
In non-standard cases, when narrowing the alveolar ridge and applying protocols with immediate loading, monolithic structures are used. They consist of an intraosseous part and a neck turning into a support head.
For fixation, screw or cement fasteners using cold welding technology are used. At the installation stage, the primary stabilization of the pin is ensured by the carved profile and additional micro thread on the neck of the implant, which distribute the load. Some species have enlarged platforms that protect the adjacent bone and increase the area of contact with tissues. The secondary fixation is responsible for the surface treatment of the rod to improve osseointegration. For this, brands use:
- plasma spray technology;
- coating with microparticles of titanium oxide, hydroxyapatite;
- Method SLA with sandblasted and acid etching.
The main types
The intraosseous parts of the pins differ in shape. In the Minsk clinic, dental implants use different sizes and configurations.
Needle or implants of the Garbaccio system
Products with a diameter of up to 1.5 mm with a length of 25-40 mm resemble a cylinder with blunt and sharp ends. It is designed for fixation between cortical plates in the alveolar ridge. The system is offered to patients with thinned bone without sinus lift. In the supragingival area, a groove is provided for connection with a surgical tip.
Blade-like or lamellar
Thin and narrow products are relevant for insertion into a thinned alveolar ridge. Plates with a rough-textured surface in the form of a groove or a snake with holes are ideal for germinating bone tissue and forming the missing volume. Perforated are relevant if the installation of an implant of a root shape is impossible. The height of the gums should be 8 mm, the thickness of the buccal-lingual zone – 3 mm.
The classic solution for dental implantation is cylindrical hollow and solid screw conical pins with different thread profiles. Self-tapping collapsible analogues similar in shape to real roots. Use with a sufficient volume of bone tissue or after a preliminary sinus lift.
Unlike threaded cylindrical implants, there are no deep notches for primary stabilization. Osteointegration is facilitated by a rough coating or fine perforation, guaranteeing the rapid growth of new tissue through the pores. During bone regeneration, it is also important to prevent the pins from being unscrewed; therefore, longitudinal grooves are formed inside the gingival sections before installing the cutter.
Hybrid structures combined elements of plate and root pins. Configurations and sizes depend on the tasks of prosthetics and anatomy of the jaw. The basis is a plate with a small screw. This type includes Swiss BOI systems, which are installed with severe tissue degeneration without building up with single-phase loading.
Types of dental implants according to the method of fixation
For each case, manufacturers offer specific solutions.
- ntra mucous or intramucous mushroom forms are used for mini implantation through the mucosa of the alveolar ridge 3 cm in size. The design is attached to the base of the prosthesis. The method is often used to better fix a removable denture.
- Submucous or submucous are used to hold a complete removable denture under the mucosa. They are fixed with magnets to the buttons of opposite polarity under the transitional fold.
- Subperiosteal (subperiosteal) systems in the form of metal scaffolds with protruding supports are inserted under the mucosal-periosteal flap with pronounced tissue resorption.
- Intraosseous or endossal are intended for classical prosthetics in the spongy bone. They are in the form of a screw, cylinder and plate, where the lower part of the pin goes into the head.
- Endodonto-endossal implants are rarely used. The principle is to insert the pins into the bone tissue through the roots of the destroyed and movable teeth.
Materials for implants
For pins, solid frames in orthopaedic dentistry exploits metals and alloys. The most expensive products are obtained from pure titanium grade Grade 1-4 ASTM, ISO. The best strength characteristics have a polymorphic metal of class 4 with an increased content of oxygen and iron. The prospect of its use is determined by the physicomechanical and biological properties shown to intraosseous implants under cyclic loads.
Upon contact with air on the metal, an inert passaging oxide layer appears, which protects against corrosion that occurs under the influence of saliva enzymes. After installing the pins on the oxide film, plasma proteins are formed, titanium ions are released near the pin. They create an intermediate layer between implants and periodontal tissues and calcium phosphate apatatite, which determines biocompatibility. Other advantages include:
- combining ability with cements and porcelain;
- a light weight;
- a small coefficient of linear expansion.
In an alternative, superplastic compositions of aluminium, vanadium, and titanium –Ti-6Al − 4V are used. Microstructure, mechanical properties are not inferior to titanium. They have superplasticity and toxicological inertness.
Based on new technologies, titanium nickelize alloys with a shape memory effect based on a matrix change due to transformation of the crystal lattice in a medium below 10 ° C have been developed. When the implant is heated during installation to a temperature of 35–37 ° C, thanks to the thermomechanical memory of the alloy, reproduce the primary form.
The basis is cobalt (70%) and chromium (30%). The materials have high hardness, strength, corrosion resistance. It is used in the manufacture of subperiosteal scaffolds. Alloys made of cobalt and stainless steel do not form a physicochemical bond with the bone while stimulating the appearance of a connective tissue membrane around the pin. Because of this, there is no tight connection with the bone, which weakens its stabilization under occlusal loading.
Since 2009, manufacturers have been manufacturing dental systems from zirconia. Unlike titanium, they are closer in colour to enamel. The translucent microstructure does not show through the crowns, so they are often installed in the smile zone. In its pure form, zirconium dioxide is fragile, and aluminium and yttrium oxides are added for strength. Hot isostatic pressing and high pressure create a monolithic structure with a tetragonal crystal lattice at times increasing mechanical strength. A random microcrack due to the expansion of tetragonal particles is immediately levelled.
Due to the fragility of the material, the pins are made of stabilized zirconium or alumina – feldspar glass with aluminium oxide. For coating using the method of hot pressing of ceramic powders, reaching under pressure the optimal density and porosity. The material is characterized by corrosion resistance, hypoallergenic, biocompatibility. Mono- and polycrystalline alumina ceramics are suitable for endo-axial plate implants and cylindrical screw systems. However, due to insufficient strength, use is limited.
Reliable manufacturers of dental implants
In our dentistry operate systems of different brands. They are similar in shape, but have structural differences and different prices.