Alain Hoornaert

Correlating implant stability to bone structure

OBJECTIVES The aim of this study was to demonstrate a possible correlation between bone microarchitecture and primary implant stability. MATERIAL AND METHODS Twenty-two implants (Ankylos((R)) and Straumann((R))) were inserted into the maxillae and mandibles of human cadavers. Bone structure was determined by computed tomography in three specimens (male, age 53; female, 67; female, 80). A strict clinical protocol was used for implantation. Primary implant stability was measured by resonance frequency analysis (Osstell Mentor). The bone structure was analyzed by micro-computed tomography (CT). Bone histomorphometrical parameters were calculated and correlated to primary implant stability. RESULTS Implant stability quotients (ISQ) ranged from 50 to 70% depending on the specimens and sites. Histomorphometry indicated differences in the bone microstructures of the specimens. However, ISQ values were not related to trabecular bone histomorphometrical parameters. The sole correlation was found between ISQ values and cortical bone thickness. CONCLUSION This study confirms the relevance for primary stability of cortical thickness around implants. The thickness of cortical bone can be assessed using a standard clinical CT.

Enhanced osseointegration of titanium implants with nanostructured surfaces: an experimental study in rabbits.

Titanium and its alloys are commonly used for dental implants because of their good mechanical properties and biocompatibility. The surface properties of titanium implants are key factors for rapid and stable bone tissue integration. Micro-rough surfaces are commonly prepared by grit-blasting and acid-etching. However, proteins and cells interact with implant surfaces in the nanometer range. The aim of this study was to compare the osseointegration of machined (MA), standard alumina grit-blasted and acid-etched (MICRO) and nanostructured (NANO) implants in rabbit femurs. The MICRO surface exhibited typical random cavities with an average roughness of 1.5 μm, while the NANO surface consisted of a regular array of titanium oxide nanotubes 37±11 nm in diameter and 160 nm thick. The MA and NANO surfaces had a similar average roughness of 0.5 μm. The three groups of implants were inserted into the femoral condyles of New Zealand White rabbits. After 4 weeks, the pull-out test gave higher values for the NANO than for the other groups. Histology corroborated a direct apposition of bone tissue on to the NANO surface. Both the bone-to-implant contact and bone growth values were higher for the NANO than for the other implant surfaces. Overall, this study shows that the nanostructured surface improved the osseointegration of titanium implants and may be an alternative to conventional grit-blasted and acid-etched surface treatments.

Cell differentiation and osseointegration influenced by nanoscale anodized titanium surfaces.

AIMS We aimed to study the interactions between human mesenchymal stem cells and the bone integration of nanostructured titanium implants. MATERIALS & METHODS Nanopores of 20, 30 and 50 nm were prepared by anodization of titanium at 5, 10 and 20 V in a mixture of fluorhydric and acetic acid. Ti 30 and 50 nanostructures promoted early osteoblastic gene differentiation of the human mesenchymal stem cells without osteogenic supplements. The osseointegration of nanostructured and control titanium implants was compared by implantation in rat tibias for 1 and 3 weeks. RESULTS The nanostructures significantly accelerated bone apposition and bone bonding strength in vivo in correlation with in vitro results. CONCLUSION These findings demonstrate that specific nanostructures controlled the differentiation of cells and, thus, the integration of implants in tissues. These nanoporous titanium surfaces may be of considerable interest for dental and orthopedic implants.

Comparative bone tissue integration of nanostructured and microroughened dental implants

AIM The aim was to compare osteointegration of nanostructured implants to a microsurface widely used for titanium dental implants. MATERIALS & METHODS Commercial titanium dental implants with smooth or microroughened surfaces were nanostructured. Implants were inserted into the femoral condyles of rabbits. After 2 and 4 weeks, histomorphometry calculation was performed. RESULTS Nanotubes measuring 60 nm in diameter were observed on both S-NANO (roughness: 0.05 μm) and R-NANO (roughness: 0.40 μm) surfaces. The MICRO surface exhibited typical random cavities (roughness: 2.09 μm). At 4 weeks, bone-to-implant contact values were significantly higher for the R-NANO than for the MICRO surface while no differences were observed at 2 weeks. CONCLUSION Overall, this study shows that the nanostructured surfaces improved osteointegration similar or higher than the MICRO.

Clinical Performance of Narrow-Diameter Titanium-Zirconium Implants: A Systematic Review

Purpose: Implant-supported prosthetic rehabilitations are in constant augmentation in everyday dental practice. This is largely due to increasing demand from patients for fixed or implant-stabilized prosthesis, although they are frequently reticent to complex preimplant bone augmentation surgeries, whenever bone volume is lacking. Narrow-diameter implants (NDI; ⩽3.5 mm) have been developed to offer relatively simple implant solutions in challenging bone-deficient sites. However, concerns regarding their mechanical properties have been raised. Special titanium-zirconium material (Ti-Zr), with superior mechanical resistance, compared with pure titanium alloys has been introduced into the market. The purpose of this systematic review was to determine the available data on clinical performance of Ti-Zr NDI. Materials and Methods: A literature search of all available clinical articles dealing with Ti-Zr NDI has been carried out. After including only prospective clinical trials, 14 papers were retrieved for thorough reviewing. Conclusion: Short-term results from preliminary clinical reports are quite promising, although the number of published studies and the follow-up periods are still insufficient to determine the real benefit of this hybrid material compared with titanium, especially when using NDI.

Silicon Nitride (Si3N4) Implants: The Future of Dental Implantology?

&NA; For decades titanium has been the preferred material for dental implant fabrication, with mechanical and biological performance resulting in high clinical success rates. These have been further enhanced by incremental development of surface modifications aimed at improving speed and degree of osseointegration and resulting in enhanced clinical treatment options and outcomes. However, increasing demand for metal‐free dental restorations has also led to the development of ceramic‐based dental implants, such as zirconia. In orthopedics, alternative biomaterials, such as polyetheretherketone or silicon nitride, have been used for implant applications. The latter is potentially of particular interest for oral use as it has been shown to have antibacterial properties. In this article we aim to shed light on this particular biomaterial as a future promising candidate for dental implantology applications, addressing basic specifications required for any dental implant material. In view of available preclinical data, silicon nitride seems to have the essential characteristics to be a candidate for dental implants material. This novel ceramic has a surface with potentially antimicrobial properties, and if this is confirmed in future research, it could be of great interest for oral use.

Bone Apposition on Nanoporous Titanium Implants

Titanium and its alloys are widely used in the biomedical field for manufacturing dental and orthopedic implants. Upon implantation in the body, the surface of these implants interacts with numerous biological entities such as proteins and cells in the nanometer range; however, most of the surfaces commercially available exhibit features in the micrometer range and thus are far not optimal for controlling the biological response. Physicochemical features in the nanometer range may ultimately control the adsorption of proteins and the adhesion and differentiation of cells. In this chapter, the different methods for producing nanotubes of titania on the surface of implants are presented. The anodization process that produces titania nanotubes is emphasized in regard to its applicability to treat complex-shaped medical devices. Then, the biomedical applications of these nanoporous surfaces in the fields of dentistry and orthopedics are presented. Future perspectives with nanometer surfaces that would ultimately direct the nature of peri-implant tissues and improve their clinical success rate are discussed.

Clinical Safety of a New Synthetic Resorbable Dental Membrane: A Case Series Study

Dental membranes are commonly used in oral and maxillofacial surgery for the regeneration of small osseous defects. A new synthetic resorbable membrane has recently demonstrated its biocompatibility and bone regeneration capacity in preclinical studies. This membrane is made of poly(D,L-lactic/glycolic acid 85/15), has a bi-layered structure with a dense film to prevent gingival epithelial cell invasion, and a microfibrous layer to support osteogenic cells and bone healing. This membrane completely degrades by hydrolysis in 4 to 6 months without signs of inflammation. Based on this research, a clinical study was conducted to evaluate the safety of the new membrane in guided tissue regeneration (GTR). In total, 26 patients (age: 50.5 ± 12.4, min-max 31-72 years; male/female 42/58%) were operated on at 7 independent private dental practices. Dental surgeons used the membrane together with various bone fillers in GTR for immediate and delayed implant placement (23 cases, 88%) and, to a lesser extent, socket preservation (2 cases, 8%) and alveolar crest augmentation (1 case, 4%). Surgeons reported an easy placement of the membrane (satisfaction index: 3.8/5). Fourteen days postsurgery, 15 patients had no pain while the others declared minimal pain (verbal rating scale: 2.2/10), and none had minor or serious complications related to the membrane. Exposure of the membrane without loosening the biomaterial granules was observed in 3 cases while mucosa healed normally over time. At 4 months postimplantation, no infection or mucosal inflammation was reported, and the overall dentist satisfaction with the clinical performance of the membrane was 4.5/5 on average. This clinical study demonstrated that the new synthetic resorbable membrane is safe for guided bone tissue regeneration in various dental surgery indications.

Chapter 5 – Impact of Nanotechnology on Dental Implants

Publisher Summary This chapter elaborates the impact of nanotechnology on dental implants. Recent studies have shown that nanometer-controlled surfaces have a great effect on early events such as the adsorption of proteins, blood clot formation, and cell behaviors occurring upon implantation of dental implants. These early events have an effective impact on the migration, adhesion, and differentiation of mesenchymal stem cells (MSCs). Studies indicate that nanostructured surfaces may control the differentiation pathways into specific lineages and ultimately direct the nature of peri-implant tissues. This chapter begins with a discussion on nanoscale surface modifications. The chapter then elaborates interactions of surface dental implants with blood. Interactions between surfaces and MSCs are also discussed. The chapter reviews the different steps of the interactions between biological fluids, cells, tissues, and surfaces of implants. Recent nanoscale surface modifications and CaP coating technologies of dental implants are discussed. The sequence of biological events in relation to surface properties is related. Mechanisms of interaction with blood, platelets, hematopoietic, and MSCs on the surface of implants are described. The chapter concludes with a discussion on tissue integration.