Surface Modification of Titanium Dental Implants Karan Gulati Editor Surface Modification of Titanium Dental Implants Editor Karan Gulati School of Dentistry The University of Queensland Herston, QLD, Australia ISBN 978-3-031-21564-3 ISBN 978-3-031-21565-0 (eBook) https://doi.org/10.1007/978-3-031-21565-0 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. 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This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Preface This book aims to present advances in the surface modification of titanium dental implants, from the macro and micro to nanoscale surface modifications, focusing on advanced bioactive and nano-engineered dental implants. Through eight chapters, the book covers a wide array of topics that provide an improved understanding of the fabrication, bioactivity, therapy, and stability of modified titanium dental implants. Overall, the book significantly contributes to the ever-changing field of dental implants. From the basics of why the surface modification is needed to the advanced state-of-the-art electrochemically anodized nanostructures fabricated on implants, the book covers the domain of dental implants from a clinical, materials science, and nano-engineering perspective. The first chapter, “Titanium: The Ideal Dental Implant Material Choice”, details the ideal characteristics of titanium that make it the most popular dental implant material choice. While modern titanium-based dental implants provide optimum treatment outcomes in healthy conditions, enhanced bioactivity and therapy are needed to ensure long-term success in compromised patient conditions. The need to modify the implant surface (especially in compromised conditions that present a significant therapeutic challenge) is thoroughly reviewed in the chapter “Titanium Dental Implants in Compromised Conditions: Need for Enhanced Bioactivity and Therapy”. Advances in dental implants have evolved from macro- to micro- to nanoscales. The chapter “Macro to Micro: Surface Modification of Titanium Dental Implants” is devoted to various macro and microscale modifications performed on titanium-based dental implants. The next generation of dental implants has con- trolled nanotopography that augments the bioactivity and therapy toward achieving timely integration and long-term success. The fourth chapter, “Nano-scale Surface Modification of Dental Implants: Fabrication”, compiles various nano-engineering tools and techniques that enable effective nanoscale surface modification of titanium dental implants, focusing on easy, scalable and cost-effective electrochemical anodization that fabricates con- trolled nanotopographies on titanium implants. Titanium dioxide (or titania) nano- tubes (like nanoscale test tubes) can be fabricated on dental implants via anodization with excellent control over their dimensions. The nanotube-modified implants offer v vi Preface various functionalities, including enhanced bioactivity and local therapy. The fifth chapter, “From Micro to Nano: Surface Modification for Enhanced Bioactivity of Titanium Dental Implants”, and the sixth chapter, “Local Therapy from Nano- engineered Titanium Dental Implants”, categorically explain the strategies employed to orchestrate implant integration and achieve tailored local therapy from anodized nanotubular dental implants, respectively. The seventh chapter, “Mechanical Stability of Anodized Nano-engineered Titanium Dental Implants”, focuses on the mechanical stability considerations of anodized dental implants. Finally, the eighth chapter, “Cytotoxicity, Corrosion and Electrochemical Stability of Titanium Dental Implants”, presents the advances and challenges associated with the cytotoxicity and corrosion of modified and nano-engineered dental implants. All chapters pres- ent clinical translation challenges and recommend future directions to advance the domain, ensuring long-term success, even in compromised patient conditions. The book is interdisciplinary and will profoundly interest a broad audience, including dentists, undergraduate/postgraduate/research students, academics, and material/biomaterial scientists. Since the book describes cutting- edge nanotechnol- ogy advances in dental implants, it will be valuable to entrepreneurs aiming to understand the next generation of nano-engineered implants. Herston, QLD, Australia Karan Gulati Contents Titanium: The Ideal Dental Implant Material Choice . . . . . . . . . . . . . . . . 1 Himanshu Arora Titanium Dental Implants in Compromised Conditions: Need for Enhanced Bioactivity and Therapy . . . . . . . . . . . . . . . . . . . . . . . . 23 Necla Asli Kocak-Oztug and Ece Irem Ravali Macro to Micro: Surface Modification of Titanium Dental Implants . . . . 61 Yifan Zhang, Shuai Li, Ye Lin, Ping Di, and Yan Liu Nano-scale Surface Modification of Dental Implants: Fabrication . . . . . . 83 Ruben del Olmo, Mateusz Czerwiński, Ana Santos-Coquillat, Vikas Dubey, Sanjay J. Dhoble, and Marta Michalska-Domańska From Micro to Nano: Surface Modification for Enhanced Bioactivity of Titanium Dental Implants . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Tianqi Guo, Sašo Ivanovski, and Karan Gulati Local Therapy from Nano-engineered Titanium Dental Implants . . . . . . . 153 Anjana Jayasree, Sašo Ivanovski, and Karan Gulati Mechanical Stability of Anodized Nano- engineered Titanium Dental Implants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Divya Chopra and Karan Gulati Cytotoxicity, Corrosion and Electrochemical Stability of Titanium Dental Implants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Tianqi Guo, Jean-Claude Scimeca, Sašo Ivanovski, Elise Verron, and Karan Gulati Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 vii Titanium: The Ideal Dental Implant Material Choice Himanshu Arora Abbreviations Å Angstrom cpTi Commercially pure titanium GPa Gigapascal HA Hydroxyapatite MPa Megapascal PEEK Polyether ether ketone Ti-6Al-4V Titanium aluminium vanadium alloy TiZr Titanium zirconium alloy ZrO Zirconium oxide 2 1 Introduction The relationship between edentulism and dentistry is as long as dentistry itself. Since then, dentists worldwide have been busy finding novel ways to limit or restore edentulism. Edentulism, whether partial or complete, has seen an increasing trend in the last few decades, with reports estimating around 120 million Americans are missing at least one tooth and approximately 35 million are completely edentulous (American College of Prosthodontists, 2022). Consequences of partial or complete edentulism range from functional, esthetic, physical, and psychological limitations affecting the overall oral health related quality of life. Various treatment options have evolved to solve this health crisis over the past few centuries with oral H. Arora (*) School of Dentistry, The University of Queensland, Herston, QLD, Australia e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 1 K. Gulati (ed.), Surface Modification of Titanium Dental Implants, https://doi.org/10.1007/978-3-031-21565-0_1 2 H. Arora implantology the latest addition to this list of options. Till date no treatment option is complete. Each treatment option must compete with the natural dentition in per- formance and long- term success. This drives the current research and advances in oral implantology to find the best performing dental implant. Dental implant is defined as a prosthetic device made of alloplastic material(s) implanted into the oral tissues beneath the mucosal and/or periosteal layer and on or within the bone to provide retention and support for a fixed or removable dental prosthesis; a substance that is placed into and/or on the jawbone to support a fixed or removable dental prosthesis (The Glossary of Prosthodontic Terms: Ninth Edition, 2017). Major advances have occurred over the last few decades in the clini- cal use of oral and maxillofacial implants. Latest statistics on the use of dental implants reveal that, in the United States alone, an estimated 5 million implants are placed annually, and a total of 15–20 million implants are placed worldwide (Misch & Misch, 2015). Dental implants are currently used to replace missing teeth, rebuild the craniofacial skeleton, provide anchorage during orthodontic treatments, and even aid in new bone formation in the process of distraction osteogenesis. In modern dentistry, the dental implant is the one of the best tooth replacement options for nearly all situations where a tooth is missing or is failing. The primary reason for this is the extremely high success rate achieved with dental implants. Saving teeth at all costs is no longer the norm because of the unpredictability of the longevity of heroic dentistry. In other words, preserving bone and tissue regenera- tion are now considered to be more important than trying to prolong tooth retention (Massa & Von Fraunhofer, 2021). One of the main reasons for the high success rate of dental implants is their abil- ity to integrate with bone in the oral environment (Misch, 2008). The goal of place- ment of endosseous dental implants is to achieve osseointegration of the bone with the implant in order to support a prosthesis (Brånemark et al., 1983; Branemark et al., 1977). The physical, chemical, and biological properties of dental implant materials along with their surface characteristics are key factors in their success (Binon, 2000; Buser et al., 1991). A wide variety of materials has been used for these implants, but only a few promote osseointegration and biointegration (Weiss & Weiss, 2001). Titanium and titanium alloys have been the most widely used of these materials. This chapter will look into the historical aspect of dental implant materials, drawing comparisons with the modern-day contemporary materials in an attempt to arrive to a conclusion ‘why titanium is the most suitable dental implant material?’. 2 Osseointegration The godfather of modern implants was a Swedish physician and anatomical and experimental biologist named Per-Ingvar Branemark. He studied bone healing response and regeneration in the 1950s and in order to observe the functioning of bone marrow in vivo, he used titanium to make a chamber that could be inserted into Titanium: The Ideal Dental Implant Material Choice 3 Fig. 1 Radiographic image of the original titanium screw placed in rabbit tibial bone by P. I. Branemark showing the integration of the implant with bone that led to discovery of osseointegration. (Albrektsson et al., 2017) rabbit legs to allow microscopic visualization of vital processes (Fig. 1). After a few months-long series of investigations, he sought to retrieve the chamber for reuse and found to his annoyance that it could not be removed from the rabbit bone (Branemark, 1983). Branemark reportedly was not struck by the significance of this turn of events until sometime after 1960, when he accepted a professorship in the Department of Anatomy at Gothenburg University. There, using an adaptation of the titanium chamber placed in the upper arms of human volunteers, he and his team investigated the workings and structure of human blood cells under a number of conditions. This work yielded a great deal of information about the nature of blood, and it showed the researchers that the titanium serving as lens casings appeared uniquely compat- ible with the human soft tissue and skin, provoking no adverse immunological reac- tions. At this point, Branemark began to contemplate using titanium for medical applications (Albrektsson et al., 2017). As this understanding advanced, Branemark believed it necessary to coin a new term to refer to the in-growth of the bone into the threads and crevices of titanium. He finally settled upon “osseointegration,” derived from the Latin words os (bone) and integro (to renew) (Branemark et al., 1977). The first and the most important event that occurs when an implant is placed in host tissue is surface adsorption of proteins. The amount, composition, and conformational changes of the adsorbed proteins influence the entire biological response to the material, including antigenic response, attachment, and growth of cells. The host response to implants placed in bone involves a series of cell and matrix events, ideally culminating in tissue healing that is as normal as possible and that ultimately leads to intimate apposition of bone to the biomaterial, i.e. an operative definition of osseointegration. For this intimate contact to occur, gaps that initially exist between bone and implant at surgery must be filled initially by a blood clot, and bone damaged during preparation of the implant site must be repaired (Szmukler- Moncler et al., 1998). The material used to construct oral implants plays a major role in the host response and has been one of the most researched topics in the field of oral implantology. 4 H. Arora 3 Materials for Endosseous Dental Implants Today, the goal of the placement of endosseous implants is to achieve osseointegra- tion at the surface of the implant. Osseointegration, as defined by Branemark, is the direct contact of the loaded implant material with living bone (Brånemark et al., 1983) (Fig. 2). The concept of osseointegration has been developed largely from the work of Branemark and was introduced in 1982 after several decades of animal work and at least a decade of work in humans (Fenton, 1992; Albrektsson et al., 2017). This concept represented a fundamental shift away from the prevailing dogma of the time. Previously, implant materials were sought which would act as inert substances, usually eliciting a fibrous encapsulation around them (Lemons, 1990). However, by definition, osseointegration demands the absence of a fibrous layer (Meffert et al., 1992), and implies that the biological response of the bone is not one of inertness toward a foreign material but rather one of integration of the material with the bone as if it were part of the body. By today’s standards, the presence of a fibrous layer between bone and implant indicates failure of the implant (Albrektsson et al., 2017; Buser et al., 2017). In spite of these definitions, there is still controversy about what osseointegration really represents. For some, osseointegration does not represent an Fig. 2 Histological photomicrograph showing a direct contact between a titanium screw/implant (black) and bone tissue using hematoxylin-eosin staining technique. (Albrektsson et al., 2017)