Use of polymer meshes in guided bone regeneration in the maxillary. Summary of the doctoral thesis in medical sciences/dentistry: 323.01 - Dentistry

Abstract

Introduction. The issue of alveolar ridge resorption and restoration remains a pressing concern in dentistry and has recently become the focus of intensive research. Various techniques and methods for restoring bone tissue have been developed to enhance the availability of suitable bone for dental implant insertion. These techniques include autologous bone blocks harvested from intraoral and extraoral donor sites, autologous bone lamellae using the Khoury method, guided bone expansion, osteogenesis through guided bone elongation, and guided bone regeneration (GBR). According to D. Buser, approximately 50% of implantation sites require a surgical procedure for bone restoration to ensure sufficient bone volume for dental implant insertion [3, p.17]. Presently, guided bone regeneration is the preferred technique for rehabilitating defects in the alveolar process to achieve the necessary bone volume for dental implantation [3]. Retzepi M. (2010) emphasized the importance of using a membrane to separate tissues, thereby enhancing the efficiency of guided bone regeneration techniques. The membranes employed in guided bone regeneration must meet several requirements: they should be biocompatible, non-toxic, and non-allergenic while maintaining adequate three-dimensional mechanical space for bone tissue formation. The first non-resorbable membranes used to augment bone supply were constructed from PTFE (polytetrafluoroethylene). They were improved by incorporating titanium strips to enhance their hardness and plasticity (Buser D 1993). The main advantage of these membranes is their ability to provide excellent mechanical stability and effectively separate the graft from the surrounding gingival soft tissues. However, PTFE and titanium membranes have several disadvantages including the extra surgical steps required for their removal, which can impact wound healing. Additionally, their rigid nature often leads to wound dehiscence when exposed, increasing the risk of infection. To mitigate the risks associated with PTFE and titanium membranes, collagen membranes and resorbable synthetic biopolymers have been introduced. These membranes, made of collagen, have limited utility due to their rapid resorption and fragile structure. Poly-4-hydroxybutyrate (P4HB) is a long-term resorbable polyester known for not creating an acidic during degradation [9]. It received clinical approval from the Food and Drug Administration (FDA) in 2007, followed by the approval of the resorbable P4HB mesh later that year. To address the limitations of existing methods, such as those made from PTFE and titanium requiring additional surgeries for removal and collagen with its short resorption time, we propose researching and developing a novel technique for guided bone regeneration of pre-implant alveolar ridges. This technique involves using resorbable polymeric surgical meshes made from poly-4-hydroxybutyrate (P4HB), which serve as both a barrier and a maintenance solution. Purpose: To evaluate the treatment of jawbone insufficiency through guided bone regeneration interventions using Poly-4-hydroxybutyrate mesh. Objectives: 1. Examining the principles and properties of membranes used in guided bone regeneration. 2. Assessing the effectiveness by comparing the use of resorbable poly-4-hydroxybutyrate meshes with titanium meshes in guided bone regeneration. 3. Investigating and establishing the histo-morphological relationships between gingival soft tissues, resorbable meshes, and newly formed bone tissue. 4. Conducting statistical analyses and interpreting the data obtained. 5. Creating an algorithm for utilizing P4HB meshes in guided bone regeneration. Research hypothesis The following theories were formulated as research hypotheses: Null hypothesis I0: The polymeric mesh, due to its prolonged resorbable character, allows for the generation of newly regenerated bone tissue similar to that obtained through titanium meshes; however, it separately induces the volumetric development of the gingival biotype, an essential factor in implant-prosthetic treatment and the prevention of complications. Alternative hypothesis IA: The polymeric mesh does not contribute to the formation of bone tissue and does not influence the gingival biotype. Scientific research methodology To achieve the aforementioned goals and objectives, we conducted a clinical cohort study involving 70 patients who underwent guided bone regeneration in the jaw, using the resorbable P4HB synthetic polymer mesh and a perforated titanium membrane. According to the research methodology, the study was developed over five years and involved two groups of 35 patients between 20 and 60. The research examined the effectiveness of the synthetic absorbable P4HB mesh in guided bone regeneration of the jaws, identified its advantages and disadvantages compared to conventional bone regeneration techniques, and established a treatment plan outlining the surgical stages of treatment with this mesh. Based on clinical and paraclinical examinations, contemporary radiological and computed tomography analysis programs were utilized, and control and surveillance measurements were conducted at 1 to 8 months, with the obtained data recorded and subsequently analyzed. The study was conducted according to the ethical principles of the Declaration of Helsinki and approved by the Ethics Committee of USMF "Nicolae Testemițanu" on 10.06.2020, with No. 43 dated 13.02.2020. This multicenter research was carried out from 2019 to 2024 within the Department of Oral-Maxillofacial Surgery and Oral Implantology "Arsenie Guțan" at the clinical facilities of Î.M.CSMC —Chișinău Municipal Dental Center and the university clinical base SRL "MASTERDENT." Main scientific results 1. 225 specialized literature sources were reviewed, highlighting the importance of separating and supporting membranes in guided bone regeneration. 2. The key requirements and principles for a separation and support membrane in guided bone regeneration were defined. 3. Seventy bone regeneration surgeries were conducted, utilizing P4HB resorbable meshes and perforated titanium membranes; patient outcomes were monitored, recorded, analyzed, and statistically interpreted, leading to formulated conclusions. 4. The study resulted in the development and proposal of a treatment algorithm for maxillary bone atrophy involving P4HB resorbable polymer in guided bone regeneration. Practical relevance The study's practical importance is that we aimed to reduce some of the shortcomings of existing guided bone regeneration methods, such as the use of PTFE and titanium meshes that need additional intervention for their removal and collagenous ones, which have a short resorption time. That's why we proposed the study and development of a new technique for guided bone regeneration

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of preimplant alveolar ridges, which consists in the use of resorbable polymeric surgical sutures with a barrier and maintenance function made of poly-4-hydroxybutyrate (P4HB). Implementation of scientific results The results of the scientific research were implemented in the research and clinical activity of the Department of Oral and Maxillofacial Surgery and Oral Implantology, "Arsenie Gutan," of the USMF "Nicolae Testemitanu." Approval of scientific results The research was discussed and presented at various national and international scientific forums: the Annual Scientific Conference at USMF "Nicolae Testemițanu" in Chișinău, from October 20-22, 2021; and the Scientific Conference commemorating the distinguished scientist Valentin Topalo, also at USMF "Nicolae Testemițanu" in Chișinău, on April 28, 2023. Participation included poster presentations at several international scientific forums: the AIT World Symposium from May 9-11, 2024, in Singapore; the European Association for Osseointegration Congress from September 26 to October 1, 2022, in Geneva, Switzerland; the 14 th edition of the EUROINVENT European Exhibition of Creativity and Innovation from May 26-28, 2022, in Iași, Romania; the 13 th edition of EUROINVENT from May 20- 22, 2021, in Iași, Romania; the International Exhibition of Scientific Research, Innovation, and Inventions PRO INVENT, 19 th Edition, in Cluj- Napoca, Romania, from October 20-22, 2021; the online International Exhibition of Inventions and Innovations “Traian Vuia,” 7 th Edition, in Timișoara, Romania, from October 6-8, 2021; and the 6 th Edition of the International Exhibition of Inventions and Innovations “Traian Vuia” in Timișoara, Romania, on October 15, 2020. The International Student Innovation and Scientific Research Exhibition – “Cadet Inova' 19” – hosted by the “Nicolae Bălcescu” Land Forces Academy in Sibiu, occurred from April 11-13, 2019, and the 11 th edition of EUROINVENT in Iași, Romania, took place from May 16-18, 2019. Based on the research project, the following honors were received: Government Excellence Scholarship and Scientific Field Scholarship for PhD students for 2022, as per DECISION No. HG 6/2022 dated 12. 01. 2022. The approval of the thesis topic occurred during the following meetings: the Meeting of the Department of Oral- Maxillofacial Surgery and Oral Implantology "Arsenie Guțan" (Minutes No. 4 of 17. 01. 2020); the Ethics Committee' s Opinion at USMF "N. Testemițanu" (No. 43 of 13. 02. 2020); and Scientific Seminar 323 in Dentistry (Minutes No. 5 of 11. 11. 2021). Publications related to the thesis topic include 13 scientific papers, 2 oral communications, 9 posters, 2 patents, 2 implementation documents, and 6 participations in various international invention forums, resulting in the following accolades: 3 gold medals, 1 silver, 1 bronze, and a diploma of excellence, along with the Government of the Republic of Moldova' s excellence scholarship and a scientific field scholarship for doctoral students for the year 2022.