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9MEDICAL SCIENCES
PLANNING THE FIXATION OF PARTIAL REMOVABLE DENTURES FOR SUBTOTAL DEFECTS
IN THE DENTITION
Guseynova Ch.
Doctor of Philosophy in Medicine, assistant Azerbaijan Medical University, Department of Orthopedic Dentistry
Baku, Azerbaijan Zeynalova Zh.
Doctor of Philosophy in Medicine, assistant Azerbaijan Medical University, Department of Therapeuticc Dentistry
Baku, Azerbaijan Zeynalov H.
Doctor of Philosophy in Medicine, assistant Azerbaijan Medical University, Department of Therapeutic Dentistry
Baku, Azerbaijan DOI: 10.5281/zenodo.7340790
Abstract
The work is devoted to the clinical problem of planning the design of partial removable dentures in cases of subtotal defects in the dentition and the preservation of single teeth on the jaws. The method of fixation is important not only for holding a removable prosthesis in the oral cavity during function, but also affects the condition of periodontal tissues, and, accordingly, the period of preservation of abutment teeth. There are different types of mechanical fasteners for removable dentures, but clasp fixation remains the most common. An alternative method of prosthetics in the presence of single teeth is the integumentary structures of removable dentures, based on the alveolar processes and roots of the teeth.
Keywords: overdentures, abutment teeth, periodontal tissues, clasp fixation, spherical attachments.
Despite the development of modern dental technologies, tooth loss remains a medical and social problem, which causes a significant need for removable prosthetics among the adult population, which, according to various authors, ranges from 26.9 to 77.3% [1]. Epidemiological studies indicate a significant prevalence of complicated caries and periodontal diseases, which are the main causes of tooth extraction [2]. Some authors explain the significant need for removable prosthetics with the aging of the population and an increase in the proportion of elderly people. It is noted that in the age group over 60 years, this need can reach 96%; the proportion of persons with large defects in the dentition of a size or more of teeth is 78.65-82.55% [3]. As a result of generalized forms of periodontal pathology, dentition defects of considerable length are formed, while severe atrophy of the alveolar processes of the jaws leads to extremely difficult conditions for orthopedic treatment [4]. The design of prostheses for subtotal defects, when only a few teeth remain on the jaws, is a complex clinical problem. Mounting on single supports does not provide reliable fixation and stabilization of prostheses and leads to a significant functional overload of periodontal tissues [7]. The most rational way to replace such defects is the use of orthopedic structures based on intraosseous implants, the installation of which makes it possible to create an effective one [5]. In many elderly people, implantation is impossible due to unfavorable clinical conditions in the oral cavity, in particular, due to significant atrophy of the bone tissue of the alveolar processes of the jaws [6]. Therefore, partial removable dentures remain the most common type of orthopedic structures used to replace distally unlimited and large included defects in
the dentition. The most commonly used design is a partial removable lamellar denture with retaining clasps. It has been proven that point clasp fixation on single teeth leads to a significant overload of their periodontium due to the action of non-physiological transversal forces in the direction [8]. The most difficult planning of the design of partial removable dentures are patients with subtotal defects of the dentition, formed as a result of generalized periodontitis, and the preservation of single teeth in the jaws. In these cases, extremely unsatisfactory conditions of anatomical retention are observed in the oral cavity, because due to previous inflammatory and degenerative processes in the bone tissue, atrophy of the alveolar processes reaches a significant degree, Ih leads to a decrease In the area of the prosthetic bed and the lack of reliable resistance to horizontal displacement. In teeth still preserved in the oral cavity, as a rule, there is atrophy of the walls of the alveoli, as a result of which the endurance of their periodontium is reduced, which leads to their rapid loss if used as a support under the clasp [9]. This problem is most critical in cases of prosthetics in the lower jaw, where the prosthetic bed is small in area and surrounded by powerful mobile tissues, which lead to significant excursions of the prosthesis during the function of speech and chewing. In the process of using mandibular prostheses with traditional clasp fixation, complications arise due to overload of the teeth due to the mobility of removable orthopedic structures. Overloading of supporting teeth leads to their destruction, rocking or removal, which further worsens the conditions for fixing removable dentures [9]. Teeth and alveolar processes present on the jaw from the vestibular and oral sides.
The advantages of integumentary structures over conventional clasps include reliable fixation due to both mechanical fasteners and functional suction, uniform distribution of masticatory pressure on the tissues of the prosthetic bed and a more physiological vertical load direction of the supporting teeth, aesthetic appearance in the absence of visible fastening elements. The development of high-precision technologies makes it possible to improve the quality of removable prosthet-ics through the use of modern types of mechanical fasteners in cover prostheses, in particular lock, bar and telescopic fixation systems in patients with subtotal defects in the dentition and the preservation of single teeth in the jaws. To conduct a comparative clinical assessment of the dynamics of atrophic changes in the periodontium of the abutment teeth in patients using removable dentures with clasp fixation and removable cover dentures with fixation on intracoronary spherical locks
Materials and methods
Examination and orthopedic treatment of 26 people aged 65-80 years with large defects in the dentition and preservation of single (1-3) teeth on the jaws with atrophy of the bone tissue of the walls of the alveoli, not exceeding the first degree, or without atrophy, was carried out. General clinical examination methods were used, as well as targeted dental radiography and computed tomography to assess the state of the bone tissue in the area of the abutment teeth. Patients were divided into two clinical groups: 12 people who were made integumentary prostheses with fixation on spherical attacks made up the main group; 14 people who had clasp-retained prostheses made were included in the control group. Patients were under dispensary observation for three years after the manufacture of removable dentures. After a comprehensive clinical examination and assessment of the condition of the periodontium of the abutment teeth, in patients of the control group, partial removable lamellar dentures were made with a fused combined base and cast retaining clasps to replace defects in the dentition.
The manufacture of prostheses was carried out according to generally accepted technologies. Patients of the main clinical group were made integumentary pros-theses with a plastic base and fixation using spherical semi-labile locks located intracoronary on pin tabs.
The supporting teeth were subject to endodontic treatment and were shortened to a level of 2 mm above the gingival margin. Root canals were prepared for solid pin inserts according to generally accepted requirements. Received anatomical prints for the manufacture of occlusal rollers and rigid individual spoons. After determining the central ratio of the jaws, individual trays were adjusted using Herbst functional tests, as in complete adentia. On the working model, modeling of pin tabs with males of spherical attachments of a removable prosthesis with matrix fastening parts in the basis was carried out. Intra-root liners were used to install the male part of the locking fastener, which was placed in the girdle part in the projection of the root center. The matrix part of the lock was installed in the base of the fixed prosthesis (Fig. 1b-c); The rigidity of the silicone matrix for fixation was chosen depending on the compliance of the mucous membrane: with a
moderate degree of compliance, yellow matrices of medium hardness were used; with a significant degree of compliance, soft red matrices were used. The formation of a marginal closing valve around the edge of the base of the prosthesis. Volumetric modeling of the edges of the basis and taking into account the functional excursions of the transitional fold provides a tight coverage of the edges of the prosthesis of the mucous valve zone. This prevents air from getting under the prosthesis, which during operation is held on the jaw due to the pressure difference between the external environment and in the space under the basis.
Research results and discussion
In the main group, 5 (41.66%) persons had a defect in the upper, 7 (58.34%) - in the lower jaw; of them with the preservation of three teeth on the jaw - 2 (14.29%), two teeth - 9 (64.29%), one tooth - 3 (21.43%) people. In the area of 15 (55.56%) abutment teeth, atrophy of the cellular walls was not detected, in 12 (44.44%) cases there was atrophy of the first degree. In the control group, 7 (43.75%) individuals had a defect in the upper, 9 (56.25%) - in the lower jaw; of these, the preservation of three teeth on the jaw - in 2 (12.5%), two - in 9 (56.25%), one - in 5 (31.25%) people. Of the total number of abutment teeth, 18 (62.07%) did not have atrophy of the cellular walls, 11 (37.93%) atrophy of the first degree was detected in the area. At the time of the start of prosthetics, there were no clinical manifestations of periodontal tissue inflammation in both groups. Clinical assessment of the results of orthopedic treatment was carried out after 6 months, 1, 2 and
3 years according to the same parameters as the presence of inflammation of the tissues of the marginal per-iodontium, the dynamics of bone tissue atrophy in the area of the abutment teeth and their loss throughout the entire period of use of prostheses.
6 months after prosthetics, no clinical changes in the state of periodontal tissues of supporting teeth in comparison with the state before prosthetics were detected in the main group; in the control group, the number of teeth with bone tissue atrophy of the first degree increased from 11 (37.93%) to 14 (48.28%). River of individuals of the main group, it was revealed that the number teeth with bone tissue atrophy of the first stage increased from 12 (44.44%) to 15 (55.56%). In the control group, the number of teeth with bone tissue atrophy of the first stage increased from 14 (48.28%) to 16 (55.17%), atrophy of the second stage was found in area
4 (13.79%) of the abutment teeth. Years after prosthetics in the main group revealed atrophy of the first degree in area 15 (55.56%), the second degree - in area 2 (7.41%) of the abutment teeth. In the area of 10 (37.04%) teeth, the cellular process did not experience atrophy. In the control group, during the second year of using dentures with clasps, 2 (6.90%) teeth were lost due to significant mobility. Atrophy of the alveolar walls was detected in the area of all preserved supporting teeth: in 15 (51.72%) cases - the first degree, the second degree - in 8 (27.59%) cases, the third degree -in 4 (13.79%) cases. 3 years in the main group without atrophy of the alveolar bone, 4 (14.81%) abutment teeth remained in the root area, with the first degree of atrophy - 15 (55.56%), with the second degree - 6
(22.22%), with the third degree - 2 (7.41%) teeth. Loss of abutment teeth in patients of the main group during the third year of using prostheses with locking fastening was not noted. In the control group, where patients used clasp-retained prostheses, during the third year the number of lost abutment teeth increased by another 6 (20.68%), first-degree atrophy was found in 5 (17.24%), and second-degree atrophy - in 8 (27.59%), third degree - in 8 (27.59%) teeth (Fig. 2). Based on the results of clinical observation, it was found that in the control group, who used the CPP with clasp fixation, atrophic changes in the periodontal tissues of the abutment teeth developed more quickly and had a more severe degree than in the main group, who used integumentary prostheses with fixation on attachments. During the recommended three-year period of using clasp prostheses in patients of the control group, 8 (27.59%) supporting teeth were lost; also at the end of this period, in the area of another 8 (27.59%) teeth, atrophy of the cellular walls reached the third degree, which made it impossible to use them for fixing any orthopedic structures. In persons of the main group, where spherical ataxations were used to fix prostheses, no cases of loss of abutment teeth due to loosening were found; at the end of the three-year period of using prostheses, teeth with a third degree of atrophy of the cellular walls were also found, but the number of such teeth is less than in the control group - 2 (7.41%) cases (against 8 (27.59%) cases in the control group).
This can be explained by the fact that the use of an integumentary prosthesis structure reduces the effect of the transversal component of the masticatory load on the abutment teeth. The use of attachments for fixing prostheses, located intracoronary in the projection of the roots, provides a more physiological distribution of masticatory pressure on the abutment tooth than in the case of using a clammer. Thus, the design of the integumentary prosthesis ensures the use of all possible factors of fixation - mechanical fastening, anatomical retention of the prosthetic bed, adhesion of the base to the mucous membrane and the creation of a closing valve along the periphery of the counterthesis base. Favorable results maintaining an acceptable state of periodontal tissues of supporting teeth is also achieved using spherical attachments in other designs of partial removable laminar and clasp dentures (Fig. 3). In the presence of single-located teeth roots, overlapping them with the base of the prosthesis and installing a locking mount allows you to create an additional fixation point for the prosthesis and slow down the process of atrophy of the edentulous areas of the alveolar processes.
Based on the study of changes in the state of the periodontal tissues of the abutment teeth during a three-year period of using integumentary prostheses with the support of molar teeth and fixation on spherical attachments and traditional PZP with retaining clasps, it was found that the use of the first type of prostheses with subto- and prognostically favorable for the period of preservation of the abutment teeth.
The location of the lock In the pr'ject'on to the center of the root and the overlap of the roots with the basis contributes to the physiological distribution of masticatory pressure and the reduction of transversal overload of the periodontium. The design of the base with the limits of a complete removable prosthesis improves fixation also due to functional suction, the absence of mechanical fasteners visible outside creates a more aesthetic appearance of prostheses.
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