Annotation
Selection of supporting teeth for clamping fixation
The supporting teeth for the arch prosthesis must meet the following requirements. First, they must be stable, have a well-defined anatomical shape and a sufficiently high clinical crown. When choosing supporting teeth, you need to carefully learn occlusal relationships. With close occlusal contact, it is very difficult, and sometimes impossible, to place a clamping support element in the figure - an occlusal patch - without disturbing the occlusal relationship. A similar situation may be the reason for using another tooth to place the supporting element, to create a special bed or cover this tooth with an artificial crown. The supporting teeth can have pathological mobility. In this case, they need to be splinted with a number of more durable teeth. When detecting chronic peri-vertebral foci of inflammation, they can be used to support only after filling the root canals.
Constructive features of an arch prosthesis on the upper and lower jaw at the І-ІІ classes according to Kennedy
With the I class by Kennedy. The clinical picture for defects of a given localization is characterized by its size, type of occlusion and the condition of the periodontium of the remaining teeth. With an increase in the defect due to loss of molar and premolar, the clinical picture becomes more complicated, which in the future will lead to an overload of the frontal group of teeth and, provided that healthy periodontal tissues are present, will lead to the erasure of the cutting surface. Therefore, this situation is an absolute indication for prosthetics. Consider the problem of an end saddle. It includes the study of biomechanics, reactive changes in the tissues of the prosthetic bed, finding opportunities to weaken the indirect action of the terminal saddle on the tissues of the prosthetic bed and the periodontitis of the remaining teeth. First, we need to characterize the forces under which the prosthesis is located. These are the forces that arise during the contraction of the masticatory muscles, and their magnitude is determined by the consistency of food, the size and shape of the chewing surface of the antagonizing artificial teeth, and the state of the mucous membrane covering the alveolar process. In addition to the magnitude, the above forces are characterized by a direction with respect to the occlusal plane. During the masticatory movements, with well preserved alveolar processes, the pressure is transferred vertically to the terminal saddle and due to well-developed rays the lateral displacements of the prosthesis are neutralized, unlike the condition when there is atrophy of the alveolar crests, which will lead to loosening of the supporting teeth. Transversal excursions of the saddle have an adverse effect on the alveolar process, accelerating the atrophy of its lateral surfaces. They can be neutralized by introducing a continuous clamper. Due to different degrees of mucosal compliance: closer to the supporting tooth - a smaller degree, and the distal - the more. The mucous membrane is unevenly compressed and atrophy increases in the distal parts of the alveolar process, the greater the pressure is on the supporting tooth, which leads to loosening of the latter. To reduce this phenomenon is possible due to the rational distribution of the load between the supporting teeth and the alveolar bone as well as the reduction of the vertical load by moving the occlusal lining to the medial part of the longitudinal groove of the tooth. It is also advisable to use a labile type of connection of a clamp with a terminal seat (load crushers); An increase in the number of supporting teeth and their combination into groups by different sewing structures; The use of shock
absorbers for chewing pressure, an increase in the area of the basis of the prosthesis. Reducing vertical pressure on the mucous membrane is also achieved by reducing the width of the artificial teeth, their number at the maximum value of the basis of the end saddle. With the weakness of the clasps, poor anatomical retention, the overturning of the end saddle can be expressed in the visible displacement of the prosthesis, which reduces its functional value. To prevent overturning, i.e. rotation of the prosthesis around the clam- meric line, the latter are provided with indirect fixators (a continuous clamp, occlusal lining, different branchings of the carcass, base sprouts, cypresses, etc.). At low clinical crowns, it is better to use fixation on telescopic crowns. In order to prevent sagging of the prosthesis, a continuous clasp should be inserted into the prosthesis construction, which will give the prosthesis greater stability during lateral movements (especially in the upper jaw). On the lower jaw, a continuous clasp, which is located on the lingual side of the teeth, serves as a support for them, strengthening their resistance to the pressure of antagonists in the anteroposterior direction. The arc here acts not only as a fixing element, but also as a splinting device. The arch of the upper jaw prosthesis is a cast metal strip with rounded edges 5-8 mm wide, 1.0-1.5 mm thick. The arc originates near the molar, repeating the shape of the sky, not reaching the distal sections to the blind palatine fossa by 1011 mm. The arc should be in relation to the mucosa at a distance of 0.5 mm. At present, instead of the classical arc, the palatal plate is used - there is no hard functional overload of the supporting teeth and the occurrence of decubitus in the sky. Its thickness is on average 0.6 mm and the wider it is, the thinner it is. Contraindication is a pronounced palatine torus. In this case, simulate a bugelite prosthesis with a window in the middle of the sky. On the lower jaw, an arc in the form of a metal strip 2-3 mm wide, 1.5-2.0 mm thick. It is located between the necks of natural teeth and a transitional fold. Be sure to consider the location of the frenum of the tongue. The distance of the arc on the lower jaw depends on the shape of the lingual sting of the alveolar bone: if it is of a vertical shape, the arch can touch the mucosa without injuring it during chewing; Sloping - to stand on 0,5 mm; Skate with a canopy - touch it in the most convex part. In the second grade by Kennedy. It is possible to use small saddle dentures with a telescopic fixation system to prevent deformations of the dentition, but it is not advisable, as with time, there is an increase in atrophy on the side of the prosthesis, as well as loosening and dislocation of supporting teeth.
It is necessary to give the advantage to increase the number of supporting teeth, use a multi-link clamp, which will prevent the tilting of the clasp prosthesis. Good fixation is created by increasing the fixing elements: the use of flip-flops. With the III and IV classes by Kennedy. In these Kennedy classes there is a problem of loss of a minimum number of teeth and with the development of secondary deformations of the dentition. It is recommended mandatory prosthetics to prevent the development of complications. Along with non-removable replacement prosthetics, these types of defects are possible with the use of small saddle-shaped prostheses. The advantage is that it is possible to not dissect the supporting teeth. But it is possible to use in the absence of no more than two teeth on the upper jaw and three on the lower jaw. And also the possible use of bugelite prostheses with flip-up clasps.