Characteristics of bone defect replacement methods and controlled bone regeneration: a comparative study

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Poltava State Medical University (Poltava, Ukraine)

Characteristics of bone defect replacement methods and controlled bone regeneration: a comparative study

Khattou V. V.

The search for methods of influence on reparative osteogenesis is an urgent issue today in modern dentistry. Over the past decade, significant progress has been made in solving this problem in scientific research and clinical practice. The goal of our study was to find effective osteoregenerative drugs for the elimination of jaw defects. A search and analysis of professional publications on the specified issue were carried out in library sources and search engines, particularly PubMed and Google Scholar. The aesthetic appearance of a modern person's smile has now become a necessary aspect of social adaptation in society, which determines the importance of such a problem today as secondary adentia, which is formed as a result of tooth extraction. Timely replacement of defects in such patients has a lot of advantages for a person, and dental implantation has become a modern alternative to other types of removable and non-removable prosthetics, which determines the normalization of the chewing and digestive process and optimization of aesthetics. But the vertical and horizontal atrophy of the alveolar process, which occurs after tooth extraction, can create negative prerequisites for the surgical stage of dental implantation and requires additional surgical interventions. Summarizing the scientific literature data, it can be stated that the use of innovative technologies for filling bone defects with osteoplastic materials capable of managing the restoration of the structure and function of bone tissue ensures stable dental rehabilitation of patients.

Key words: osteoregeneration, bone defect of jaws, adentia, replacement of bone defects.

Connection of the publication with planned research works

The work was performed within the framework of the Department of Surgical Stomatology and Maxillofacial Surgery of the Poltava State Medical University on the topic: «Diagnostics, surgical and medical treatment of patients with injuries, defects and deformations of tissues, inflammatory processes of the maxillofacial area» (state registration number 0119U102862).

Introduction

Even though tooth extraction is the most common intervention in the outpatient practice of surgical dentistry until now, the issue of preventing post-extraction complications and finding ways to preserve an adequate amount of bone tissue in the alveolar process does not lose relevance. In addition, the problem of atrophy of the jaws, which occurs after a tooth's loss, is becoming increasingly urgent due to the widespread introduction of dental implants into clinical practice. To date, dental implantation has become the «golden» standard for rehabilitating patients with adentia, the success of which depends on the optimal amount of bone tissue in the alveolar process. Therefore, the search for effective osteoregenerative drugs to eliminate jaw defects is significant at the current stage of the development of surgical dentistry [1, 2, 3, 4].

The aim of the study.

To conduct an in-depth analysis of modern professional literature devoted to modern methods of replacing bone defects and directed bone regeneration formed after tooth extraction against inflammatory diseases.

Object and research methods.

In the funds of the scientific library of the Poltava State Medical University and scientometric information databases (PubMed, Google Scholar,) a search, review, analysis and systematization of professional publications devoted to the problem of applying modern methods of replacing bone defects and directed bone regeneration in a comparative aspect was carried out.

Research results and their discussion

The analysis and generalization of a relatively large array of scientific publications, both foreign and domestic publications, devoted to the study of reparative osteogenesis allows us to conclude that targeted stimulation and regulation of reparative processes in bone tissue, as well as a direct influence on cells of bone regeneration, is carried out with the help of such methods: (1) autogenous and allogeneic bone tissue transplantation; (2) xenotransplantation; use of (3) phytogenic, (4) synthetic, and (5) composite bone substitutes; (6) directed bone regeneration; (7) tissue engineering.

The method of autotransplantation of bone tissue is one of the most common in maxillofacial surgery. It is considered the «gold standard» [5, 6] for the treatment of several diseases due to the possibility of obtaining a predictable reparative and clinical result [7].

Autografts are usually obtained from intraoral and extraoral donor sites [8], for example, mandibular symphysis, mandibular ramus, external oblique crest, iliac crest, proximal ulna, or distal radius, which are the source of cortical and cancellous bone tissue [ 9, 10].

Cancellous bone is most often used for autotransplantation because it contains osteoblasts and progenitor cells with significant osteogenic potential. In addition, they have relatively large trabecular surfaces that facilitate the creation of an osteoinductive environment by stimulating revascularization processes. Cortical bone, in contrast, does not contain osteoblasts and osteogenic cells, providing structural and mechanical integrity and promoting bone healing through osteo- conduction. Furthermore, cortical grafts integrate more slowly than cancellous grafts because of their limited revascularization potential. Thus, to maximize the productivity of bone remodelling, a combination of cancellous and cortical bone tissue [3] or vascularized bone autografts [11] is used.

However, despite the favourable properties of autologous bone tissue (complete histocompatibility, lack of immunogenicity, ability to quickly revascularize, etc.), its use in clinical practice has several disadvantages, including the need to create an additional operating area and a limited amount of donor material [12, 13].

Therefore, as an alternative to the autogenous bone, allogeneic transplant materials were proposed, which avoid the need for additional surgical trauma, shorten the duration of the reconstructive procedure, and obtain relatively accessible and inexpensive material for transplantation [14, 15]. As a rule, the allograft is obtained either from a compatible living donor or from cadaveric bone sources and is prepared in three primary forms - fresh, frozen or freeze-dried [3]. Fresh and frozen allograft materials have good osteoinductive properties but are currently rarely used due to the high probability of an immunogenic response of the recipient, limited shelf life and increased risk of transmission of such infectious diseases as HIV, hepatitis B and C [16]. These problems can be avoided to some extent by sterilization, mechanical cleaning, and ultrasonic or gamma irradiation of tissues, but the such treatment of the allograft material reduces its osteoinductive potential, structural strength and osseointegration [17, 3].

One of the forms of alloplastic materials, which is quite successfully used to restore the height and thickness of alveolar bone after tooth extraction, as well as to fill periodontal bone defects [18, 19, 20], is demineralized bone matrix [21, 17, 3, 7]. It is usually synthesized from cortical bone [22] by acid removal of the mineral mesh, exposing the trabecular bone framework rich in bone morphogenic protein and growth factors (TGF-P and FGF). The latter can stimulate the differentiation of mesenchymal stem cells into osteoblasts, providing osteoinductive properties higher than those of cancellous or cortical allografts [19, 17, 12, 23]. At the same time, despite relatively high osteoinductive characteristics, the demineralized bone matrix has poor mechanical properties, to improve which it is often combined with other allografts or composite bone substitute materials [12, 9, 24].

Even though the use of auto- and allografts allows in some cases to achieve a noticeable clinical improvement to overcome their inherent limitations (related primarily to the risk of infectious complications and immunological reactions), researchers-practitioners turn to the development of natural substitutes for bone tissue - xenografts [17]. The most common source of materials for xenografts is deproteinized bovine bone, which, due to the similarity of structural, mechanical and biochemical properties to human bone tissue, turns out to be an effective osteoconductive material for transplantation. Currently, the products OsteoGrafTM, Cerabone™ [25], and BioOss™ [26] made based on bovine bone have proven themselves well in the practice of reparative maxillofacial surgery, in particular, when augmentation of the maxillary sinus [27, 28, 29, 30].

Another common material for xenotransplantation is chitosan, a natural polymer obtained from crustacean exoskeletons consisting of glucosamine and N-acetyl- glucosamine [4]. It can stimulate bone regeneration, providing a structural framework and promoting the differentiation of mesenchymal stem cells into osteoblasts [31]; however, due to the low mechanical properties of chitosan, to obtain a stronger fibrous structure with an adhesive hydrophilic surface, it is often combined with other materials - gelatin, calcium phosphates, and bioglass [32, 33]. Recent studies have indicated the successful use of chitosan-based materials as membranes for directed bone regeneration, periodontal regeneration, and alveolar bone height restoration [34, 35].

For the production of xenografts, silk - a natural biopolymer mainly consisting of proteins, fibroin and sericin - has recently been used. After the removal of sericin, silk fibroin is commonly used in sponge, fibre, film, and hydrogel [36, 37, 38] and as a membrane for directed bone regeneration [37, 39, 40]. reparative osteogenesis jaw defect

Despite the promising prospect of clinical application of many xenograft materials described above, there are still some limitations regarding their use [13], which prompts researchers to search for new osteogenic materials of plant and synthetic origin [24, 41].

Another alternative is phytogenic bone substitute materials usually obtained from plants, corals, and seaweed [12, 24, 17, 42, 7]. For example, the dried rhizome of the perennial pteridophyte Drynaria fortune - Gu- Sui-Bu - is a phytopreparation that increases the catalytic functions of alkaline phosphatase, contributing to the processes of bone calcification and its remodelling through the regulation of the activity of osteoclasts and osteoblasts [43, 44]. Calcium carbonate and crystalline hydroxyapatite, which contain coral-based bone substitutes [12, 24, 45], promote the healing of periodontal, alveolar, and maxillary sinus bone defects by improving vascularization and mineralization processes [46, 47, 48]. Several studies have proven the clinical effect of AlgiPore™ material obtained from seaweed, which was used for maxillary sinus plastic [49, 50], as well as as a filler (in combination with other materials) of the postextraction cavity to prevent deformation of the alveolar crest [51]. At the same time, despite relatively good osteoconductive properties and low immunogenicity, it is indicated that phytogenic materials are fragile and have relatively low tensile strength and poor resorptivity [52, 24, 13, 41].

To stimulate reparative osteogenesis in the replacement of jaw defects, synthetic bone analogues that accurately imitate the biological properties of natural bone tissue are also used with variable success: calcium phosphates, polymers and metals [53, 25].

Conclusions

Summarizing the scientific literature data, it can be stated that there is no doubt that there is a need to bring tooth extraction operation to a qualitatively new level, which would create conditions for maximum preservation of bone tissue and full rehabilitation of patients. It should be noted that the use of innovative technologies for filling bone defects with osteoplastic materials, which can manage the restoration of the structure and function of bone tissue, ensure high-quality and stable dental rehabilitation of patients.

Prospects for further research.

They consist in the experimental and clinical substantiation of the use of modern osteoplastic drugs to create a stable architecture of the alveolar process after tooth extraction against the background of the inflammatory process.

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