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Impacto da radioterapia de cabeça e pescoço nos tecidos dentários: alterações estruturais e efeito de dentifrícios fluoretados

Wed, 15 Jul 2026 00:00:00 GMT

Title: Impacto da radioterapia de cabeça e pescoço nos tecidos dentários: alterações estruturais e efeito de dentifrícios fluoretados Abstract: Radiotherapy is one of the main therapeutic modalities used in the treatment of head and neck cancer. However, it may lead to complex oral complications. Radiation-related caries (RRC) is characterized by a more rapid and aggressive progression than conventional dental caries, typically initiating with enamel cracking and delamination, followed by dentin exposure to the oral environment. The direct effects of ionizing radiation on dental tissues include changes in microhardness, disruption of the collagen network, and obliteration of dentinal tubules, making the management of this condition particularly challenging and highlighting the importance of preventive strategies. Although the efficacy of fluoride is well established, evidence regarding the effects of different fluoride concentrations on irradiated dental substrates remains limited. The aim of this thesis was to evaluate the structural alterations induced by radiotherapy in dental tissues and to investigate the effects of toothpastes containing different fluoride concentrations on irradiated tissues through complementary studies, encompassing structural and crystallographic changes as well as the response of dental tissues to fluoride-based preventive strategies. To achieve this, three in vitro laboratory studies were conducted, presented as Chapters 1, 2, and 3. Chapter 1 aimed to correlate the mechanical and solubility properties of enamel with radiation-induced crystallographic changes, considering the proximity to the dentino-enamel junction (DEJ). The methodologies included two-dimensional synchrotron radiation X-ray microdiffraction (SR-µXRD), Vickers microhardness, fracture toughness, and citric and lactic acid solubility tests. The irradiated enamel exhibited lower microhardness values and greater acid solubility than the non-irradiated enamel. Furthermore, SR-µXRD revealed changes in the crystallographic parameters and texture of irradiated hydroxyapatite. Chapter 2 investigated the effects of radiation on the surface properties of demineralized human dentin following pH cycling and toothpaste treatment. Knoop microhardness, Atomic Force Microscopy (AFM), and Scanning Electron Microscopy (SEM) were employed. Under the in vitro conditions of this study, irradiated and non-irradiated dentin showed similar behavior regarding microhardness and surface roughness after being subjected to the same pH-cycling protocol and treatment with fluoride toothpastes. Chapter 3 evaluated the effects of toothpastes containing different fluoride concentrations on the mechanical and surface properties of irradiated and non-irradiated dentin after pH cycling. The same methodologies described in Chapter 2 were used. The results demonstrated that different fluoride concentrations produced distinct responses in irradiated dentin. The toothpaste containing 5,000 ppm fluoride resulted in higher microhardness values and lower surface roughness than the fluoride-free toothpaste and the 1,450 ppm fluoride toothpaste. In conclusion, head and neck radiotherapy promotes significant structural changes in dental tissues, as evidenced by crystallographic alterations in enamel hydroxyapatite. Furthermore, fluoride toothpastes demonstrated the potential to mitigate the deleterious effects of ionizing radiation on dentin.

Evolução da terapia com Fibrina Rica em Plaquetas (PRF) na prática odontológica: tubos plásticos sem aditivos como alternativa na produção de PRF, biofuncionalização de hidroxiapatita sintética com Protocolo Progressivo PRO-PRF e uma série de casos

Fri, 16 Jan 2026 00:00:00 GMT

Title: Evolução da terapia com Fibrina Rica em Plaquetas (PRF) na prática odontológica: tubos plásticos sem aditivos como alternativa na produção de PRF, biofuncionalização de hidroxiapatita sintética com Protocolo Progressivo PRO-PRF e uma série de casos Abstract: Platelet-Rich Fibrin (PRF) has emerged as a promising autologous biomaterial in tissue engineering and the biofunctionalization of synthetic materials, particularly in regenerative bone procedures. This thesis aimed to investigate key aspects related to the preparation, characterization, and clinical application of PRF, with emphasis on the use of plastic tubes without additives and the biofunctionalization of synthetic hydroxyapatite (HA) using the third-generation Progressive PRF (PRO-PRF) protocol. In Chapter 1, the density of the fibrin network, platelet aggregates, and cellular morphology of three PRF protocols obtained in glass or plastic tubes, with or without silica coating, were evaluated. Eight volunteers (n = 8) participated in the study, from whom nine blood samples were collected per individual. The samples were divided into three groups according to tube material and centrifuged using the following protocols: Leukocyte- and Platelet-Rich Fibrin (L-PRF – 700 g/12 min), Advanced Platelet-Rich Fibrin (A-PRF – 200 g/14 min), and Advanced Platelet-Rich Fibrin Plus (A-PRF+ – 200 g/8 min). The membranes were analyzed by light microscopy (LM) to assess fibrin and platelet density and by transmission electron microscopy (TEM) for qualitative evaluation of cellular morphology. Membranes obtained from plastic tubes without additives exhibited significantly lower fibrin network density in the L-PRF (p < 0.019) and A-PRF (p < 0.001) protocols. A significantly higher percentage of platelets was observed in membranes produced in plastic tubes without additives, regardless of the protocol used (p < 0.005). Ultrastructural morphology and cellular integrity were preserved in all groups. In Chapter 2, the distribution pattern of HA biofunctionalized with three protocols was investigated: L-PRF, GM350, and PRO-PRF. The study included eight participants (n = 8), with approximately 48 mL of blood collected in six plastic tubes without additives at three different time points. The tubes were divided into three groups according to the centrifugation protocol: L-PRF, GM350 (350 g/15 min), and PRO-PRF (60 g/5 min, 200 g/5 min, and 700 g/5 min). The fluid material was aspirated and transferred to glass containers (5 mL) containing 0.25 g of HA. After polymerization, the clots were compressed to form blocks. Density analysis by micro-computed tomography revealed no significant differences among L-PRF (37.95 ± 0.40), GM350 (39.13 ± 2.29), and PRO-PRF (34.62 ± 4.05; p = 0.132). The PRF/HA ratio, assessed by LM, was significantly lower in PRO-PRF compared with L-PRF (55.14 ± 1.65; p = 0.033) and GM350 (57.10 ± 4.66; p = 0.014). Scanning electron microscopy (SEM) revealed a dense three-dimensional fibrin network integrated with HA. Chapter 3 described a series of four clinical cases involving the application of HA biofunctionalized with PRO-PRF in maxillary sinus floor elevation procedures. Preliminary clinical and tomographic outcomes demonstrated significant vertical bone gain after 120 days (mean: 8.07 mm), and no postoperative complications observed, suggesting that HA biofunctionalization with PRO-PRF represents a safe and promising strategy to enhance tissue repair.

Padronização do diagnóstico em disfunções temporomandibulares: uma análise da aplicação do DC/TMD em contextos acadêmicos, clínicos e desenvolvimento tecnológico.

Wed, 10 Dec 2025 00:00:00 GMT

Title: Padronização do diagnóstico em disfunções temporomandibulares: uma análise da aplicação do DC/TMD em contextos acadêmicos, clínicos e desenvolvimento tecnológico. Abstract: This thesis comprises three interconnected studies with a shared objective: to make the application of the DC/TMD protocol more objective, accessible, and reproducible in dental clinical practice. The overarching aim is to enhance the diagnosis of temporomandibular disorders (TMD) through standardization, technological integration, and professional training. The first study investigated the prevalence of TMD in patients with Parkinson’s Disease and highlighted substantial limitations in applying the DC/TMD in this population. The need for prior administration of the Mini-Mental State Examination (MMSE), along with the requirement for trained professionals, restricts the reproducibility of the protocol in individuals with even mild cognitive impairment. This underscores the need for diagnostic approaches that are both adaptable and straightforward in neurologically affected populations. The second study evaluated the knowledge and confidence of dental students regarding TMD diagnosis and management. Although most students demonstrated solid theoretical knowledge, they reported low confidence in clinical decision-making. A key barrier identified was the limited exposure to structured diagnostic tools like DC/TMD, revealing a disconnect between academic instruction and clinical readiness. Addressing these challenges, the third study developed and validated a diagnostic software based on DC/TMD. Applied to 154 patients, the digital tool showed high agreement with manual diagnoses (Kappa > 0.8), supporting its reliability as a clinical and educational aid. The software proved capable of minimizing diagnostic variability and broadening the reach of standardized protocols, even for users still in training. General conclusion: These studies converge in their pursuit of strategies that promote more accurate, efficient, and consistent use of the DC/TMD protocol. The integration of scientific evidence, clinical education, and technological innovation emerges as a powerful path toward improving TMD diagnosis and ensuring higher quality and equity in dental care.

Efeito do protocolo de cimentação e uso de protetor bucal no desempenho biomecânico de laminados cerâmicos e facetas diretas em resina composta

Mon, 24 Jul 2023 00:00:00 GMT

Title: Efeito do protocolo de cimentação e uso de protetor bucal no desempenho biomecânico de laminados cerâmicos e facetas diretas em resina composta Abstract: Ceramic laminate veneers and direct composite veneers became more popular nowadays, therefore clarifying some topics about the light curing protocol and the interaction between light curing units and luting agents is very important, as well as clarifying aspects about protection of these restorations using mouthguards with and without modifications. The first objective was to evaluate the effect of moving the mono or multiwave light curing units and different exposure times on the degree of conversion and Knoop microhardness of light-cured resin cements with different photoinitiators. The results showed that localized exposure for 40 s resulted in better mechanical properties of the resin cements, unlike the moving LCU protocol and different photoinitiators were not affected by mono or multiwave LCU. The second objective evaluate the presence and thickness of ceramic laminate veneer and the protection with mouthguards with and without antagonist tooth contact by finite element analysis. It was concluded that 4 mm mouthguard generated similar behavior in 0.3 and 1 mm similar to healthy teeth, and the contact with antagonist tooth improved the stress distribution. The third objective evaluated the modification of a mouthguard with hard insert and air-space on the protection of direct composite veneers. Results showed that with the use of mouthguard the strain decreased and the conventional mouthguard presented higher shock absorption, similar to the air-space, on the other side, mouthguard with hard insert presented the lowest shock absorption. The fourth objective was to condense the results of the first three papers and to disclose with a clinical focus for publication in a national journal. The paper resulted on the condensation of the results and generated some guidelines to facilitate clinical application by dentists.