Dental implant surface modifications and osteointegration

Osteointegration can be defined as the direct contact between the living bone and the implant surface without interposed soft tissue at the microscope level and it is a critical process to guarantee implant stability and consequent short and long term clinical success. Several factors are known to influence the efficiency of the osteointegration: bone status; loading conditions; implant design and material; implant surface and surgical technique. Surface conditions are particularly important as they play a major role in the osteointegration process. Several characteristics among implant surface, such as surface composition, physic-chemical properties, surface wettability and roughness influence the rate and quality of osteointegration. Over the past three decades, the use of dental implants raised exponentially and widely expanded among the dental manufactures. The growing interest in improving the dental implant/bone interface has been addressed through the use of several techniques available for the modification of the surfaces dental implants in order to induce bioactivity. Different surface properties can induce different gene and protein expression in the osteogenic cells and also different structural and biomechanical properties to the surrounding mineralized tissue. This can result in different speed, quantity and quality of peri-implant bone formation. Nowadays, a growing aspect of endosseous implant surface research is focused on further enhancing the activity of bone forming cells at the tissue implant interface through the understanding of the fundamental processes at the interface between implant surfaces and surrounding living tissues. The goal of this study is to review the contemporary knowledge about the influencing factors affecting the osteointegration process of dental implants, analyze the currently available techniques for implant surface modification and their limitations, and also discuss the future trends in surface bioengineering and nanotechnology for improving the osteointegration and consequently enhance their biological performance.A osteointegração, definida como sendo o contato direto estabelecido entre o tecido ósseo e a superfície de um implante com carga funcional, desconsiderando a interposição dos tecidos moles, é considerada como sendo uma fator crítico na manutenção da estabilidade do implante e, consequentemente, do seu sucesso clínico a curto e longo prazo. Vários são os fatores que influenciam a eficácia da osteointegração: o status do osso, as condições de carga, a anatomia e material do implante, as propriedades da sua superfície e a técnica cirúrgica utilizada. As propriedades da superfície do implante são um fator relevante no processo de osteointegração, na medida em que são várias as características das superfícies que afetam a quantidade, qualidade e a rapidez de concretização deste fenómeno. Sejam elas, a constituição da superfície, as propriedades físico-químicas, a molhabilidade e a rugosidade. A utilização de implantes dentários tem vindo a aumentar exponencialmente nas últimas três décadas, o que deu origem a uma rápida expansão do seu mercado. O crescente interesse em melhorar a qualidade da sua interface com o tecido ósseo, tem levado a desenvolver várias técnicas de modificação das superfícies implantares, procurando desta forma, induzir a sua bioatividade. Diferenças nas propriedades da superfície dos implantes revelam ter influência na expressão génica e na ação proteica ao nível das células osteoblásticas resultando, desta forma, em diferenças qualitativas e quantitativas na formação do tecido ósseo peri-implantar. Atualmente, os avanços na investigação de superfície de implantes endo-ósseos visam melhorar a atividade de células osteoblásticas na interface osso-implante. O objetivo do presente estudo consiste numa revisão do conhecimento atual sobre os fatores que influenciam o fenómeno da osteointegração, na análise das técnicas de modificação de superfície mais utilizadas, bem como das suas limitações. Pretende também discutir novas orientações em áreas como a nanotecnologia e bioengenharia de superfícies, avaliando de que forma podem estas áreas melhorar o seu desempenho clínico

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research