Subgingival microbiota and immune response modulation of osseointegrable implants / Modulação da microbiota subgengival e resposta imune dos implantes osseointegráveis

ABSTRACT Osseointegrable dental implants are biomaterials made of titanium or other alloys mixed with titanium, which have high biocompatibility and allow osseointegration. However, this process can be modulated by changes in the complex mechanisms between microbiota, immune response and host. The present study aims to present how the immune system-microbiota-host interaction influences the osseointegration process of titanium dental implants and its alloys. A literature review was performed through electronic and manual searches in several databases, including PubMed, LILACS, Google Scholar, SciELO and Web of Science for articles published in the last 20 years in English and Portuguese. The formation of a temporary fibrin matrix on the implants surface after implantation implies the recruitment, adhesion and activity of immune cells at this site, with the release of pro-inflammatory molecules and recruitment of neutrophils. In the second moment, monocytes and macrophages (M1) are recruited, producing, in this step, reactive oxygen species. In the later stage of inflammation, macrophages (M2) help in tissue regeneration with expression of anti-inflammatory cytokines. In addition, the implants surface provides a site for microbial colonization mediated by salivary pellicle and topographical features. Thus, in symbiosis the modulation of the immune response will be favorable to osseointegration. However, the dysbiotic process exacerbates the inflammatory progression modulating the immune response influencing abnormal tissue healing or scar and fibrosis formation, compromising osseointegration. Different conditions of the subgingival microbiota will influence different immunological cascades, generating different cellular responses and positive or negative modulation of the osseointegration process.

RESUMO Os implantes dentários osseointegráveis são biomateriais constituídos de titânio ou outras ligas misturadas com titânio, as quais possuem alta biocompatibilidade e permitem a osseointegração. Esse processo pode ser modulado por alterações nos mecanismos complexos entre microbiota, resposta-imune e hospedeiro. O presente estudo busca apresentar como a interação sistema imune-microbiota-hospedeiro influenciam no processo de osseointegração proveniente de implantes dentários de titânio. Foi realizada uma revisão de literatura através de busca eletrônica e manual em diversas bases de dados, incluindo PubMed, LILACS, Google Acadêmico, SciELO e Web of Science para artigos publicados nos últimos 20 anos em inglês e português. A formação de uma matriz provisória de fibrina na superfície dos implantes após a implantação implica no recrutamento, adesão e atividade das células imunes, com a liberação de moléculas pró-inflamatórias e recrutamento de neutrófilos. No segundo momento, monócitos e macrófagos (M1) são recrutados, produzindo espécies reativas a oxigênio. Já no estágio posterior da inflamação, macrófagos (M2) ajudam na regeneração do tecido com expressão de citocinas anti-inflamatórias. Além disso, a superfície dos implantes oferece um local para colonização microbiana mediada pela película salivar e características topográficas. Assim, em simbiose a modulação da resposta imune vai ser favorável à osseointegração. Contudo, em estado de doença periodontal, o processo disbiótico exacerba a progressão inflamatória modulando a resposta imune influindo em um processo cicatricial comprometendo a osseointegração. Diferentes condições da microbiota subgengival vão influenciar em cascatas imunológicas diferentes gerando respostas celulares diferentes e modulação positiva ou negativa do processo de osseointegração.

The peri-implant ligament: a scoping review

The peri-implant ligament is formed from the interface of bone tissue, through the anchoring of proteins and the surface of the dental implant. In this sense, it is relevant to understand the extent to which this ligament is structured and biomimics the periodontal ligament functions. Aim: The goal of this scoping review is to present and analyze the peri-implant ligament composition and compare the extent to which this ligament is structured and biomimics the periodontal ligament functions. Methods: This scoping review was performed according to the Joanna Briggs Institute methodology for scoping reviews and following the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for scoping review. Two independent researchers searched Pubmed, Cochrane, Embase, Virtual Health Library, Scielo, Scopus, Web of Science, Brazilian Bibliography of Dentistry, Latin American and Caribbean Literature in Health Sciences, Digital Library of Theses and Dissertations from the University of São Paulo and Portal Capes. Studies published in English, Portuguese and Spanish, over the last 21 years (2000-2021). Results: A total of 330 titles were identified and after applying inclusion and exclusion factors, 27 studies were included in this review. All proteins were identified regarding their tissue function and classified into 6 major protein groups. After that this new protein ligament was compared with the periodontal ligament regarding its function and composition. The main proteins associated with osseointegration, and thus, with the peri-implant ligament are recognized as belonging to the periodontal ligament. Conclusion: This scoping review results suggest evidence of the composition and function of the periimplant ligament. However, variations may still exist due to the existence of several modulants of the osseointegration process

Nutritional influences on oral infections: the oral microbiota modulation

Introduction: The oral microbiota has approximately 700 symbiotic microorganisms responsible for oral health homeostasis. However, changes in oral microbiota can generate dysbiotic processes that favor the worsening of infections such as caries and periodontal disease. These oral infections, in addition to systemic involvement, can compromise the teeth integrity as well as oral health. Thus, inadequate nutrition proves to be a risk factor influencing the prevention and treatment of these oral infections. Objective: This study aims to evidence the nutritional influence on the oral microbiota modulation affecting, in the longterm, the gut microbiota, highlighting the use of probiotics and prebiotics in the treatment of oral infections by a literature review. Synthesis of data : Supplements of certain nutrients and the intake of an adequate diet in macronutrients and micronutrients directly influence nutritional status and consequently in the maintenance of oral-systemic homeostasis. In addition, due to microbial multidrug resistance, therapies using probiotics and prebiotics have been adopted as aids to the treatment of oral infections. Conclusion: Personalized Dentistry must integrate multidisciplinary knowledge of attention for health care. This in addition to knowingwhen to refer and work together with a Nutritionist.

Introdução: A microbiota oral possui aproximadamente 700 microrganismos simbiontes responsáveis pela homeostase da saúde bucal. Contudo, alterações na microbiota oral podem gerar processos disbióticos que favorecem o agravamento de infecções como a cárie e a doença periodontal. Essas infecções orais, além do acometimento sistêmico, podem comprometer a integridade dos dentes e também da saúde bucal. Dessa forma, a alimentação inadequada mostra-se um fator de risco que influência na prevenção e no tratamento dessas infecções orais. Objetivo: Este estudo visa evidenciar a influência nutricional na modulação da microbiota oral afetando a longo prazo a microbiota intestinal, destacando o uso de probióticos e prebióticos no tratamento de infecções orais através de uma revisão de literatura. Síntese de dados: A suplementação de determinados nutrientes e a ingestão de uma dieta adequada em macronutrientes e micronutrientes influenciam diretamente no estado nutricional e consequentemente na manutenção da homeostase oral-sistêmica. Além disso, devido à multirresistência microbiana, terapias com probióticos e prebióticos têm sido adotadas como auxiliares no tratamento de infecções orais. Conclusão: A Odontologia Personalizada deve integrar conhecimentos multidisciplinares de atenção à saúde. Isso além de saber quando encaminhar e trabalhar junto com o Nutricionista.

Lithium chloride improves bone filling around implants placed in estrogen-deficient rats.

OBJECTIVE: This study evaluated the ability of lithium chloride (LiCl) to increase bone filling (BF) around threaded titanium implants inserted in estrogen-deficient rats and, thein-vitro effects of this drug on osteoblast-like cell viability, proliferation, mineralization and expression of bone-related markers. DESIGN: In vivo: Rats received sham surgery plus water (Estrogen-sufficient group), ovariectomy plus water (Estrogen-deficient group) or ovariectomy plus LiCl (150 mg/kg/every other day) (LiCl/estrogen-deficient group). On the 21st day after ovariectomy/sham surgeries, a threaded titanium implant was inserted in the rat tibia. BF and the number of TRAP + cells were assessed at 10, 20 and 30 days after implant placement. In vitro: Osteosarcoma SAOS-2 cells were exposed to 0, 0.01, 0.05, and 0.1 mM of LiCl; cell proliferation, viability, mineralization (alizarin red staining) and gene expressions of RUNX-2, OCN, OPN, BSP and ALP (Real Time PCR) were estimated in the cultures. RESULTS: In vivo: The estrogen-sufficient and LiCl/estrogen-deficient groups demonstrated higher percentages of BF, within the limits of implant threads, than the estrogen-deficient group at 20 and 30 days (p < 0.05). The number of TRAP + cells was lower in LiCl/estrogen-deficient than in the estrogen-deficient group at all experimental times (p < 0.05). In vitro: Cell cultures exposed to LiCl (0.01 or 0.05 mM) exhibited larger areas of mineralized matrix than the non-exposed cultures (p < 0.05) and demonstrated the highest expressions of the genes investigated. CONCLUSION: LiCl treatment improved BF around threaded titanium implants inserted in estrogen-deficient rats and stimulated matrix mineralization and overexpression of bone-formation markers in osteoblastic cells in culture.

Lithium chloride assuages bone loss in experimental periodontitis in estrogen-deficient rats.

OBJECTIVES: Evidence shows that lithium, a medication commonly used for bipolar disorder treatment, presents bone anabolic activity. This study evaluated the effects of lithium chloride on periodontitis-induced bone loss (BL) and on intact alveolar bone during estrogen sufficiency and deficiency. MATERIALS AND METHODS: Rats (24/group) received sham surgery plus water (estrogen-sufficient group), ovariectomy plus water (estrogen-deficient group), sham surgery plus lithium chloride (150 mg/kg/every other day) (lithium/estrogen-sufficient group), or ovariectomy plus lithium chloride (lithium/estrogen-deficient group). One first mandibular molar received ligature, while the contralateral molar was left unligated. BL and trabecular bone area (TBA) were assessed in the furcation bone at 10, 20, and 30 days after ligature placement. Histochemical staining for TRAP and immunohistochemical staining for osteocalcin, osteopontin, osteoprotegerin, and RANKL were evaluated at 30 days after ligature placement. RESULTS: At 10 days, the estrogen-deficient group presented the highest BL (0.115 ± 0.026), while the lithium/estrogen-deficient group (0.048 ± 0.024) presented the lowest BL in the ligated teeth (p < 0.05). At 20 and 30 days, the estrogen-deficient group exhibited significantly higher BL than all the other groups (p < 0.05). The ligated teeth of the lithium/estrogen-sufficient group presented the highest TBA while those of the estrogen-deficient group presented the lowest TBA at 10 and 30 days (p < 0.05). Unligated teeth of lithium-treated groups had stronger staining for osteocalcin and osteopontin than the estrogen-deficient group (p < 0.05). Ligated and unligated teeth of the estrogen-deficient group exhibited lower expression of osteoprotegerin than the other groups (p < 0.05). Lithium-treated groups exhibited generally higher staining of RANKL than the untreated groups (p < 0.05). Unligated teeth in both estrogen-sufficient groups presented lower TRAP expression than both estrogen-deficient groups (p < 0.05). CONCLUSIONS: Lithium chloride reduced ligature-induced BL in estrogen-deficient rats and yielded an overall greater trabecular area and overexpression of bone markers in alveolar bone under normal and deficient estrogen states. CLINICAL RELEVANCE: Lithium chloride may be a promising agent to assuage alveolar bone loss related to periodontitis, especially in osteoporotic conditions.

Análise in vitro da estabilidade de próteses totais superiores implantossuportadas e implantorretidas / Analisys of the stability of maxillary overdentures

Os sistemas de retenção utilizados em próteses totais sobre implante (sobredentaduras) tem sido discutidos ao longo das últimas décadas a fim de se obter uma padronização a respeito do tratamento clínico desses pacientes. Considerando o importante papel da estabilidade das próteses para a eficiência mastigatória, bem como para elaboração do plano de tratamento adequado, o objetivo deste estudo foi avaliar a estabilidade das próteses implantossuportadas e/ou implantorretidas, utilizando para isso um estudo in vitro que simulou a força de mordida. Materiais e Métodos: Foram testadas quatro tipo diferentes de próteses totais: 1) G1 – Prótese Total Removível Convencional; 2) G2 - Próteses Total Removível sobre Implantes (Overdenture), retida pelo sistema ERA®; 3) G3 – Prótese Total Removível sobre Implantes (Overdenture), retida pelo sistema de Barra com clipes e Encaixes - ORCE; e 4) G4 - Prótese Total Fixa sobre Implantes, seguindo o protocolo Brånemark e utilizando o sistema de barras-distais da marca Neodent®. Cada grupo foi submetido ao carregamento em pontos específicos, localizados sobre os elementos 16 (F=300N), 26 (F=300N) e na região anterior 11/21(F=100N). A aferição da estabilidade foi feita através da mensuração do deslocamento vertical da prótese durante o a aplicação da força e a distância do local do carregamento, sobre os elementos 16, 26 e na região anterior, nos elementos 11 e 21. Os dados passaram no teste de normalidade de Shapiro-Wilk e foram submetidos à análise de variância ANOVA e à comparação múltipla através do teste de Bonferroni (p<0.05) Resultados: O tipo de sistema utilizado influenciou na movimentação vertical da prótese na região posterior contralateral à aplicação de força, sendo a movimentação vertical G1 > G2 > G3 ≥ G4. Na movimentação vertical da prótese nos dentes anteriores, quando a força foi aplicada nos dentes posteriores (rotação para posterior), a movimentação vertical ...

The retain systems used by the complete dentures have been discussed over the past decades in order to achieve a standardization regarding to the clinical treatment of the patients. Considering the important meaning of the stability of dentures for chewing efficiency and for planning appropriate treatment, the aim of this study was to evaluate the stability of the implant-supported and implant-retained prosthesis, using an in vitro study that simulated the bite force. Materials and Methods: Four different types of dentures were tested: 1) G1 - Conventional Denture; 2) G2 – Overdenture retained by the ERA ® system ; 3) G3 - Overdenture retained by bar system using clipes and fittings; and 4) G4 - Total implant-supported Prosthesis, following the Brånemark protocol and using Neodent®`s distal bar. Each group was subjected to loading at specific points, located on the elements 16, 26 (F = 300Ncm) and at the anterior region 11/21 (F = 100Ncm). The measurement of vertical displacement during the test was taken out-lying from the loading area and at the elements 16, 26 and in the anterior region, at the element 11/21. Results: The data was analyzed by Shapiro -Wilk normality Test and than by ANOVA and multiple comparisons using the Bonferroni test. Conclusions: The retention system have influenced the vertical movement of the prosthesis in the posterior region contralateral to force application point, with the vertical movement as G1 > G2 > G3 > G4. In the vertical movement of the prosthesis at anterior point, when the force was applied to the posterior teeth, the vertical movement was G1 > G2 > G3 > G4. When the load was applied to the anterior teeth and movement was measured ate the posterior teeth, the behavior was G1 > G2 > G3 > G4. In two of the three situations simulated, there was no statistical difference between the vertical ...