Periodontal-type measurements associated with hydroxyapatite-coated and non-HA-coated implants: uncovering to 36 months

Fitting pieces into the puzzle: The impact of titanium-based dental implant surface modifications on bacterial accumulation and polymicrobial infections

Polymicrobial infection is the main cause of dental implant failure. Although numerous studies have reported the ability of titanium (Ti) surface modifications to inhibit microbial adhesion and biofilm accumulation, the majority of solutions for the utilization of Ti antibacterial surfaces have been testedin in vitro and animal models, with only a few developed surfaces progressing into clinical research. Motivated by this huge gap, we critically reviewed the scientific literature on the existing antibacterial Ti surfaces to help understand these surfaces' impact on the "puzzle" of undesirable dental implant-related infections. This manuscript comprises three main sections: (i) a narrative review on topics related to oral biofilm formation, bacterial-implant surface interactions, and on how implant-surface modifications can influence microbial accumulation; (ii) a critical evidence-based review to summarize pre-clinical and clinical studies in an attempt to "fit pieces into the puzzle" to unveil the best way to reduce microbial loads and control polymicrobial infection around dental implants showed by the current in vivo evidence; and (iii) discussion and recommendations for future research testing emerging antibacterial implant surfaces, connecting basic science and the requirements for future clinical translation. The findings of the present review suggest no consensus regarding the best available Ti surface to reduce bacterial colonization on dental implants. Smart release or on-demand activation surface coatings are a "new piece of the puzzle", which may be the most effective alternative for reducing microbial colonization on Ti surfaces, and future studies should focus on these technologies.

Immediate and early loading of hydrothermally treated, hydroxyapatite-coated dental implants: a 7-year prospective randomized clinical study

Background

Existing research on marginal bone stability around hydroxyapatite (HA)-coated implants often lacks adequate long-term follow-up. The purpose of this randomized prospective study was to evaluate the 7-year outcome of patients with immediate and early loaded single-tooth restorations supported by implants with plasma-sprayed, partially HA-coated surfaces. Forty-two patients in need of 50 single implants were treated in in the Postgraduate Periodontics Clinic of Louisiana State University School of Dentistry. Implants were randomly divided into 2 groups: Group A was immediately loaded, and Group B was early loaded. Continuous follow-up with periodic maintenance care and radiographic evaluations was performed. The primary outcome of interest was implant survival, characterized using the Kaplan–Meier method. Secondary study outcome consisted of peri-implant crestal bone level changes. Data on age, sex, bone quality, implant location, length and diameter, and prior augmentation of the site were collected. Multiple regression analyses were conducted to determine whether the independent variables were associated with bone loss.

Results

One implant failed to maintain stability and was removed at 3 weeks. Thirty-four patients (14 males, 20 females with a total of 42 implants) completed the 7-year follow-up visit. Average age of evaluable patients was 52 in Group A and 55 in Group B. No significant difference was observed regarding sex and age distribution between the 2 groups. No significant difference was detected in the distribution of implant locations, types of bone, implant length, implant diameter, and augmentation status of the bone between the 2 groups. After 7 years of functioning for the 42 implants examined, implant survival rate was 100% for Group A and 95.5% for Group B. The results from this study of 50 implants showed that HA-coated Zimmer Tapered Screw-Vent Implants were clinically effective, with an overall cumulative 7-year survival rate of 98.0%. When comparing radiographic bone levels between 2-year and 7-year follow-ups, no significant differences in bone loss were found between Group A and Group B.

Conclusions

After 7 years in function, implants partially coated with plasma-sprayed and hydrothermally treated HA were clinically predictable when restored in occlusion immediately after or 3 weeks after implant placement.

Customized Therapeutic Surface Coatings for Dental Implants

Dental implants are frequently used to support fixed or removable dental prostheses to replace missing teeth. The clinical success of titanium dental implants is owed to the exceptional biocompatibility and osseointegration with the bone. Therefore, the enhanced therapeutic effectiveness of dental implants had always been preferred. Several concepts for implant coating and local drug delivery had been developed during the last decades. A drug is generally released by diffusion-controlled, solvent-controlled, and chemical controlled methods. Although a range of surface modifications and coatings (antimicrobial, bioactive, therapeutic drugs) have been explored for dental implants, it is still a long way from designing sophisticated therapeutic implant surfaces to achieve the specific needs of dental patients. The present article reviews various interdisciplinary aspects of surface coatings on dental implants from the perspectives of biomaterials, coatings, drug release, and related therapeutic effects. Additionally, the various types of implant coatings, localized drug release from coatings, and how released agents influence the bone–implant surface interface characteristics are discussed. This paper also highlights several strategies for local drug delivery and their limitations in dental implant coatings as some of these concepts are yet to be applied in clinical settings due to the specific requirements of individual patients.

Treatments for enhancing the biocompatibility of titanium implants

Titanium surface treatment is a crucial process for achieving sufficient osseointegration of an implant into the bone. If the implant does not heal sufficiently, serious complications may occur, e.g. infection, inflammation, aseptic loosening of the implant, or the stress-shielding effect, as a result of which the implant may need to be reoperated. After a titanium graft has been implanted, several interactions are crucial in order to create a strong bone-implant connection. It is essential that cells adhere to the surface of the implant. Surface roughness has a significant influence on cell adhesion, and also on improving and accelerating osseointegration. Other highly important factors are biocompatibility and resistance to bacterial contamination. Bio-inertness of titanium is ensured by the protective film of titanium oxides that forms spontaneously on its surface. This film prevents the penetration of metal compounds, and it is well-adhesive for calcium and phosphate ions, which are necessary for the formation of the mineralized bone structure. Since the presence of the film alone is not sufficient for the biocompatibility of titanium, a suitable surface finish is required to create a firm bone-implant connection. In this review, we explain and compare the most widely-used methods for modulating the surface roughness of titanium implants in order to enhance cell adhesion on the surface of the implant, e.g. plasma spraying, sandblasting, acid etching, laser treatment, sol-gel etc., The methods are divided into three overlapping groups, according to the type of modification.

Achievements in the Topographic Design of Commercial Titanium Dental Implants: Towards Anti-Peri-Implantitis Surfaces

Titanium and its alloys constitute the gold standard materials for oral implantology in which their performance is mainly conditioned by their osseointegration capacity in the host's bone. We aim to provide an overview of the advances in surface modification of commercial dental implants analyzing and comparing the osseointegration capacity and the clinical outcome exhibited by different surfaces. Besides, the development of peri-implantitis constitutes one of the most common causes of implant loss due to bacteria colonization. Thus, a synergic response from industry and materials scientists is needed to provide reliable technical and commercial solutions to this issue. The second part of the review focuses on an update of the recent findings toward the development of new materials with osteogenic and antibacterial capacity that are most likely to be marketed, and their correlation with implant geometry, biomechanical behavior, biomaterials features, and clinical outcomes.

Osteogenesis-Related Gene Expression and Guided Bone Regeneration of a Strontium-Doped Calcium-Phosphate-Coated Titanium Mesh

Guided bone regeneration using a perforated titanium membrane is actively used in oral and orthopedic surgeries to provide space for the subsequent filling of a new bone in the case of bone defects and to achieve proper bone augmentation and reconstruction. The surface modification of a titanium membrane using a strontium-substituted calcium phosphate coating has become a popular trend to provide better bioactivity and biocompatibility on the membrane for improving the bone regeneration because strontium can stimulate not only the differentiation of osteoblasts but also inhibit the differentiation of osteoclasts. The strontium-doped calcium phosphate coating on the titanium mesh was formed by the cyclic precalcification method, and its effects on bone regeneration were evaluated by in vitro analysis of osteogenesis-related gene expression and in vivo evaluation of osteogenesis of the titanium mesh using the rat calvarial defect model in this study. It was identified that the strontium-doped calcium phosphate-treated mesh showed a higher expression of all genes related to osteogenesis in the osteoblast cells and resulted in new bone formation with better osseointegration with the mesh in the rat calvarial defect, in comparison with the results of untreated and calcium phosphate-treated meshes.

A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants

The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the outcome variables were (a) percentage annual complication rate (ACR) and (b) cumulative success rate (CSR), as presented in the selected articles. The electronic search yielded 645 titles. On the basis of the inclusion criteria, 8 studies were finally included. The percentage of implants in function after the first year was estimated to be 98.4 % in the maxilla and 99.2 % in the mandible. The estimates of the weighted mean ACR-percentage increased over the years up to 2.6 (SE 0.7) during the fifth year of function for the maxilla and to 9.4 (SE 8.4) for the mandible in the tenth year of function. After 10 years, the mean percentage of successful implants was estimated to be 71.1 % in the maxilla and 72.2 % in the mandible. The estimates seem to confirm the proposed, long-term progressive bone loss pattern of CaP-ceramic-coated dental implants. Within the limits of this meta-analytic approach to the literature, we conclude that: (1) published long-term success data for calcium phosphate plasma-spray-coated dental implants are limited, (2) comparison of the data is difficult due to differences in success criteria among the studies, and (3) long-term CSRs demonstrate very weak evidence for progressive complications around calcium phosphate plasma-spray-coated dental implants.

Immediate and Early Loading of Hydrothermally Treated, Hydroxyapatite-Coated Dental Implants: 2-Year Results from a Prospective Clinical Study

This investigation was undertaken to determine if multithreaded implants partially coated with plasma-sprayed hydroxyapatite (HA) could be effectively loaded earlier than 3-6 months after placement. Forty-eight patients (22 men, 26 women) were enrolled in the study and received 48 implants. The population was divided into 2 groups: A implants (n = 23) were loaded immediately on the day of surgery and group B implants (n = 19) were loaded 3 weeks after surgery. Cone beam computerized tomography (CBCT) scans were taken preoperatively to aid in treatment planning. Bone density was evaluated by tactile feedback during surgery. Insertion torque was recorded at time of implant placement. Resonance frequency analysis, performed on the day of surgery, at the time of loading, and at 6, 12, and 24 months, was used to record implant stability according to the unit's implant stability quotient (Osstell ISQ). Standardized radiographs were taken at time of implant placement and at 6, 12, and 24 months to measure crestal bone stability. Bone level changes were measured by software (Image J). Bone quality was judged as either type 1 (n = 1), 2 (n = 31), 3 (n = 15), or 4 (n = 1). There were no failures in the group A (survival = 100%, n = 23/23) and 1 failure in group B (survival = 94.7%, n = 18/19). After 2 years in function, cumulative mean radiographic bone loss was 0.75 ± 0.50mm (maxillae: 0.92 ± 0.49 mm, n = 14; mandibles: 0.67 ± 0.49 mm, n = 28). No differences in bone levels were noted between implants placed in previously augmented and nonaugmented sites, and there were no periodontal or soft tissue complications. After 2 years in function, implants partially coated with plasma-sprayed and hydrothermally treated HA were clinically predictable when restored in occlusion immediately after or within 3 weeks of implant placement.

Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

The present work is a revision of the processes occurring in osseointegration of titanium dental implants according to different types of surfaces -namely, polished surfaces, rough surfaces obtained from subtraction methods, as well as the new hydroxyapatite biomimetic surfaces obtained from thermochemical processes. Hydroxyapatite’s high plasma-projection temperatures have proven to prevent the formation of crystalline apatite on the titanium dental implant, but lead to the formation of amorphous calcium phosphate (i.e., with no crystal structure) instead. This layer produce some osseointegration yet the calcium phosphate layer will eventually dissolve and leave a gap between the bone and the dental implant, thus leading to osseointegration failure due to bacterial colonization. A new surface -recently obtained by thermochemical processes- produces, by crystallization, a layer of apatite with the same mineral content as human bone that is chemically bonded to the titanium surface. Osseointegration speed was tested by means of minipigs, showing bone formation after 3 to 4 weeks, with the security that a dental implant can be loaded. This surface can be an excellent candidate for immediate or early loading procedures.

Key words:Dental implants, implants surfaces, osseointegration, biomimetics surfaces.

A Critical Review of Dental Implant Materials with an Emphasis on Titanium versus Zirconia

The goal of the current publication is to provide a comprehensive literature review on the topic of dental implant materials. The following paper focuses on conventional titanium implants and more recently introduced and increasingly popular zirconia implants. Major subtopics include the material science and the clinical considerations involving both implant materials and the influence of their physical properties on the treatment outcome. Titanium remains the gold standard for the fabrication of oral implants, even though sensitivity does occur, though its clinical relevance is not yet clear. Zirconia implants may prove to be promising in the future; however, further in vitro and well-designed in vivo clinical studies are needed before such a recommendation can be made. Special considerations and technical experience are needed when dealing with zirconia implants to minimize the incidence of mechanical failure.

A review paper on biomimetic calcium phosphate coatings

Biomimetic calcium phosphate coatings have been developed for bone regeneration and repair because of their biocompatibility, osteoconductivity, and easy preparation. They can be rendered osteoinductive by incorporating an osteogenic agent, such as bone morphogenetic protein 2 (BMP-2), into the crystalline lattice work in physiological situations. The biomimetic calcium phosphate coating enables a controlled, slow and local release of BMP-2 when it undergoes cell mediated coating degradation induced by multinuclear cells, such as osteoclasts and foreign body giant cells, which mimics a physiologically similar release mode, to achieve sustained ectopic or orthotopic bone formation. Therefore, biomimetic calcium phosphate coatings are considered to be a promising delivery vehicle for osteogenic agents. In this review, we present an overview of biomimetic calcium phosphate coatings including their preparation techniques, physico-chemical properties, potential as drug carrier, and their pre-clinical application both in ectopic and orthotopic animal models. We briefly review some features of hydroxyapatite coatings and their clinical applications to gain insight into the clinical applications of biomimetic calcium phosphate coatings in the near future.

Characterization of hydroxyapatite containing a titania layer formed by anodization coupled with blasting

OBJECTIVES

The modification of dental implant surface by increasing the surface roughness or/and altering chemical composition have been attempted. Among them, hydroxyapatite (HA) coatings are typically bioactive. On the other hand, titania coatings have good corrosion resistance and biocompatibility. Therefore, the objective of this study was to fabricate HA containing a titania layer using an HA blasting and anodization method to benefit from the advantages of both, followed by surface characterization and biocompatibility.

MATERIALS AND METHODS

HA blasting was performed followed by microarc oxidation (MAO) using various applied voltages (100, 150, 200, 250 V). For surface characterization, the microstructure of the surface, surface phase and surface roughness were observed. Bonding strength was measured using a universal testing machine and potentiodynamic corrosion testing was performed. Biocompatibility was evaluated based on bioactivity and cell proliferation test.

RESULTS

The porous titanium oxide-containing HA was formed at 150 and 200 V. These surfaces were a lower corrosion current compared to the titanium treated only with HA blasting. In addition, composite treated titanium showed a rougher surface and tighter bonding strength compared to the titanium treated only with MAO. Biocompatibility demonstrated that HA/Titania composite layer on titanium showed a rapid HA precipitation and also enhanced cell proliferation.

CONCLUSIONS

These results suggested that HA containing titania layer on titanium had not only excellent physicochemical, mechanical and electrochemical properties, but also improved bioactivity and biological properties that could be applied as material for a dental implant system.

The effect of APH treatment on surface bonding and osseointegration of Ti-6Al-7Nb implants: an in vitro and in vivo study

This study investigated the effects of anodization-cyclic precalcification-heat (APH) treatment on the bonding ability of Ca-P coating to the parent metal and osseointegration of Ti-6Al-7Nb implants. Eighteen Ti-6Al-7Nb discs, 9 untreated and 9 APH-treated, were cultured with osteoblast cells in vitro, and the cellular differentiation ability was assayed at 1, 2, and 3 weeks. For in vivo testing, 28 Ti-6Al-7Nb implants (14 implants of each group) were inserted to rat tibias, and after each 4 and 6 weeks of implantation, bone bonding, and osseointegration were evaluated through removal torque and histological analysis. Osteoblast-culturing showed twice as much of the alkaline phosphatase activity on the treated surface at 3 weeks than on the untreated surface (p < 0.05). The treated implants exhibited higher removal torque values than the untreated ones (15.5 vs. 1.8 Ncm at 4 weeks and 19.7 vs. 2.6 Ncm at 6 weeks, p < 0.05). Moreover, the excellent bonding quality of coats was confirmed by the existence of cohesive fractures on the surface of removed APH implants (field emission scanning electron microscopy and histological observation). Within the limits of this study, it can be concluded that the APH treatment significantly enhanced osseointegration of the Ti-6Al-7Nb implant, with the stable bonding between the coating and the implant surface.

Evaluation of osseointegration of titanium alloyed implants modified by plasma polymerization

By means of plasma polymerization, positively charged, nanometre-thin coatings can be applied to implant surfaces. The aim of the present study was to quantify the adhesion of human bone cells in vitro and to evaluate the bone ongrowth in vivo, on titanium surfaces modified by plasma polymer coatings. Different implant surface configurations were examined: titanium alloy (Ti6Al4V) coated with plasma-polymerized allylamine (PPAAm) and plasma-polymerized ethylenediamine (PPEDA) versus uncoated. Shear stress on human osteoblast-like MG-63 cells was investigated in vitro using a spinning disc device. Furthermore, bone-to-implant contact (BIC) was evaluated in vivo. Custom-made conical titanium implants were inserted at the medial tibia of female Sprague-Dawley rats. After a follow-up of six weeks, the BIC was determined by means of histomorphometry. The quantification of cell adhesion showed a significantly higher shear stress for MG-63 cells on PPAAm and PPEDA compared to uncoated Ti6Al4V. Uncoated titanium alloyed implants showed the lowest BIC (40.4%). Implants with PPAAm coating revealed a clear but not significant increase of the BIC (58.5%) and implants with PPEDA a significantly increased BIC (63.7%). In conclusion, plasma polymer coatings demonstrate enhanced cell adhesion and bone ongrowth compared to uncoated titanium surfaces.

Calcium orthophosphates in dentistry

Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.

Bone regeneration related to calcium phosphate-coated implants in osteoporotic animal models: a meta-analysis

BACKGROUND

Osteoporosis is a frequent human metabolic bone disorder. Prospectively, global ageing of populations will lead to a major increase of subjects being diagnosed with osteoporosis and in need for dental rehabilitation. However, as local osteoporosis of the jaws affects bone quantity and quality of edentulous regions, osseointegration of dental implants might be hampered. Consequently, calcium phosphate ceramic-coated implants have been suggested to compensate for low bone quantity/density and for impaired bone healing in osteoporosis. Nonetheless, up to now no meta-analytical assessment of the relevant preclinical literature to quantify such a possible positive effect has been undertaken.

MATERIALS AND METHODS

PubMed search, limited to animal models, to identify a possible positive effect of calcium phosphate-coated implants on bone regeneration, was carried out. Further, the reference lists of related review articles and publications selected for inclusion in this review were systematically screened. The primary outcome variables were bone-to-implant contact percentage as assessed histomorphometrically and mechanical stability testing.

RESULTS

The electronic search in the database of the National Library of Medicine resulted in the identification of 2704 titles. These titles were initially screened by the two independent reviewers for possible inclusion, resulting in further consideration of 51 publications. Screening the abstracts led to 22 full-text articles. From these articles, 16 reports were excluded. Finally, six of these original research reports could be selected for evaluation. Additionally, eight publications were identified by manual search. Thus, a total of 14 articles were included for analysis.

CONCLUSIONS

It was concluded that (1) in osteoporotic animal models calcium phosphate ceramic-coated implants are associated with improved bone-to-implant healing as compared to noncoated implants. Moreover, (2) essentially due to quality characteristics of the analyzed original research articles a negative impact of osteoporosis on bone-to-implant healing could not be confirmed. Besides, (3) the established positive bone-to-implant healing effect of calcium phosphate ceramic coatings does not differ between osteoporotic and nonosteoporotic, healthy animal models.

Macrochanneled bioactive ceramic scaffolds in combination with collagen hydrogel: a new tool for bone tissue engineering

New tissue-engineering tool for bone regeneration is described to facilitate homogeneous cell seeding and effective osteogenic development. Calcium phosphate (CaP) scaffolds with macrochanneled and well-defined pore structure was developed, however, a large portion of the cells seeded directly within the scaffold easily penetrates without good adhesion to the scaffold surface. To overcome this, a method was exploited to dispense cells evenly throughout the CaP scaffold using collagen hydrogel. Rat bone marrow-derived mesenchymal stem cells (MSCs) were mixed within a neutralized collagen solution, which was then infiltrated into the macrochanneled pore space and gelled to result in macrochanneled bioceramic scaffold combined with MSCs-hydrogel. MSCs contained within the hydrogel-CaP scaffolds were highly viable, with similar growth pattern to those in the collagen hydrogel. Cells seeded by this approach were initially almost double in number compared with those seeded directly onto the CaP scaffold and had an active proliferation more than 14 days. Assessments of the MSCs showed significantly higher alkaline phosphatase levels in the combined scaffold, which was accompanied by enhanced osteogenesis including the expression of genes [collagen type I, bone sialoprotein, and osteopontin (OPN)] and proteins (OPN and osteocalcin). Extracellular calcium was also elevated significantly in the combined scaffold compared to the CaP scaffold. In addition, mechanical strength of the constructs was improved significantly in the combined scaffold compared to the CaP scaffold. Based on these, the cell culturing and tissue engineering strategy within the macrochanneled bioactive ceramic scaffolds could be improved greatly by the combinatory approach of using collagen hydrogel.

Early outcome of an implant system with a resorbable adhesive calcium-phosphate coating--a prospective clinical study in partially dentate patients

This study aims to investigate the early outcome of a dental implant with bioactive calcium-phosphate (CaP) coating in the first year of usage in different clinical indications in partially edentulous patients, after early and delayed prosthetic loading. Therefore, in a prospective follow-up study, the cumulative survival and success rate of a conical, self-drilling and self-tapping implant system after 6 months and 1 year post-insertion was evaluated. A total of 311 CaP-coated implants were placed in 124 patients. Seventy-two implants in clinical high-quality bone situation were loaded after 2 weeks post-insertion with the definite restoration; the rest after 6 months. The indication for implant placement was treatment of partial dentate mandible and maxilla. One hundred sixty-three implants were placed in the posterior mandible, 117 in the posterior maxilla. In the frontal maxilla, 25 implants and in the frontal mandible, eight implants were used. In 126 cases (36%), bone augmentation procedures (guided bone regeneration and sinus lift) were performed concomitant with implant placement. The difference between primary and secondary stability (implant stability quotient (ISQ), Periotest, insertion torque), peri-implant clinical parameter as well as survival and success criteria were evaluated. In total, ISQ mean values after 6 months were higher than after implant placement. Periotest values increased in the period of the first 6 months and remained constant afterwards. After 6 months of insertion, the mean bone loss was 0.051 mm. After 12 months, a bone gain with a mean of +0.016 mm was observed; implants in the posterior maxilla showed significant less bone resorption than implants in the posterior mandible (p < 0.0001). In the most of the implants (74%), clinical normal gingival tissue could be observed. In 24%, a mild inflammation was analysed. In 35 implants, a provocation of peri-implant bleeding was possible. In the early loading group, no implant failure was seen. Altogether, one implant in D4 bone has been lost. The cumulative survival rate summed up to 99.7%. In general, implant success assessment analysis according to Albrektsson and Buser displayed success in 99.7% of the implants. With respect to the patient selection including 124 implants with minor and major augmentations as well as early loading prosthetic function, the 1-year clinical use of the studied implant system with CaP coating showed good results, comparable to that of conventional implants without a specific coating. After 1 year, neither special disadvantages nor benefits of CaP-coated implants could be evaluated. Long-term results are further needed.

Nucleation and growth of octacalcium phosphate on treated titanium by immersion in a simplified simulated body fluid

A simplified simulated body fluid solution (S-SBF) was used to study the kinetics and mechanism of nucleation and growth of octacalcium phosphate (OCP) on the surfaces of alkali and heat-treated titanium samples. After the alkali and heat treatments, the samples were soaked in S-SBF for periods varying up to 24 h. A thin layer of poorly crystallized calcium titanate was formed after 15 min of immersion, allowing for the deposition of another layer of amorphous calcium phosphate (ACP). After 2.5 h of immersion, OCP nuclei were observed on the surface of the ACP layer. After 5 h of immersion in S-SBF solution, the specimens were completely covered with a homogeneous plate-like layer of OCP. Analyses by transmission electron microscopy revealed that nucleation and growth of OCP occurred concomitantly to the crystallization of ACP in hydroxyapatite (HA). This transformation took place by solid-state diffusion, forming a needle-like HA structure underneath the OCP film.

Surface modification of a Ti-7.5Mo alloy using NaOH treatment and Bioglass coating

The objective of this study was to propose a surface modification for a low-modulus Ti-7.5Mo alloy to initiate the formation of hydroxyapatite (HA) during in vitro bioactivity tests in simulated body fluid (SBF). Specimens of commercially pure titanium (c.p. Ti) and Ti-7.5Mo were initially immersed in a 15 M NaOH solution at 60 degrees C for 24 h, resulting in the formation of a porous network structure composed of sodium titanate (Na(2)Ti(5)O(11)). Afterwards, bioactive Bioglass particles were deposited on the surface of NaOH-treated c.p. Ti and Ti-7.5Mo. The specimens were then immersed in SBF at 37 degrees C for 1, 7 and 28 days, respectively. The apatite-forming ability of the NaOH-treated and Bioglass-coated Ti-7.5Mo was higher than that of the c.p. Ti under the same condition. The X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) results indicated that the deposited amounts of calcium phosphate were much greater for the surface-treated Ti-7.5Mo than for the c.p. Ti, a finding attributable to or correlated with the higher pH value of the SBF containing surface-treated Ti-7.5Mo. Moreover, in the surface-treated Ti-7.5Mo, the pH value of the SBF approached a peak of 7.66 on the first day. A combination of NaOH treatment and subsequent Bioglass coating was successfully used to initiate in vitro HA formation in the surface of the Ti-7.5Mo alloy.

Effects of implant surface coatings and composition on bone integration: a systematic review

OBJECTIVE

The aim of the present review was to evaluate the bone integration efficacy of recently developed and marketed oral implants as well as experimental surface alterations.

MATERIALS AND METHODS

A PubMed search was performed for animal studies, human reports and studies presenting bone-to-implant contact percentage or data regarding mechanical testing.

RESULTS

For recently developed and marketed oral implants, 29 publications and for experimental surface alterations 51 publications fulfilled the inclusion criteria for this review.

CONCLUSIONS

As demonstrated in the available literature dealing with recently developed and marketed oral implants, surface-roughening procedures also affect the surface chemical composition of oral implants. There is sufficient proof that surface roughening induces a safe and predictable implant-to-bone response, but it is not clear whether this effect is due to the surface roughness or to the related change in the surface composition. The review of the experimental surface alterations revealed that thin calcium phosphate (CaP) coating technology can solve the problems associated with thick CaP coatings, while they still improve implant bone integration compared with non-coated titanium implants. Nevertheless, there is a lack of human studies in which the success rate of thin CaP-coated oral implants is compared with just roughened oral implants. No unequivocal evidence is available that suggests a positive effect on the implant bone integration of peptide sequences or growth factors coated on titanium oral implants. In contrast, the available literature suggests that bone morphogenetic protein-2 coatings might even impede the magnitude of implant-to-bone response.

Randomized clinical trials in implant therapy: relationships among methodological, statistical, clinical, paratextual features and number of citations

OBJECTIVES

The aim of the present study was to investigate the relationships among reported methodological, statistical, clinical and paratextual variables of randomized clinical trials (RCTs) in implant therapy, and their influence on subsequent research.

MATERIALS AND METHODS

The material consisted of the RCTs in implant therapy published through the end of the year 2000. Methodological, statistical, clinical and paratextual features of the articles were assessed and recorded. The perceived clinical relevance was subjectively evaluated by an experienced clinician on anonymous abstracts. The impact on research was measured by the number of citations found in the Science Citation Index. A new statistical technique (Structural learning of Bayesian Networks) was used to assess the relationships among the considered variables.

RESULTS

Descriptive statistics revealed that the reported methodology and statistics of RCTs in implant therapy were defective. Follow-up of the studies was generally short. The perceived clinical relevance appeared to be associated with the objectives of the studies and with the number of published images in the original articles. The impact on research was related to the nationality of the involved institutions and to the number of published images.

CONCLUSIONS

RCTs in implant therapy (until 2000) show important methodological and statistical flaws and may not be appropriate for guiding clinicians in their practice. The methodological and statistical quality of the studies did not appear to affect their impact on practice and research. Bayesian Networks suggest new and unexpected relationships among the methodological, statistical, clinical and paratextual features of RCTs.

Surface treatments of titanium dental implants for rapid osseointegration

The osseointegration rate of titanium dental implants is related to their composition and surface roughness. Rough-surfaced implants favor both bone anchoring and biomechanical stability. Osteoconductive calcium phosphate coatings promote bone healing and apposition, leading to the rapid biological fixation of implants. The different methods used for increasing surface roughness or applying osteoconductive coatings to titanium dental implants are reviewed. Surface treatments, such as titanium plasma-spraying, grit-blasting, acid-etching, anodization or calcium phosphate coatings, and their corresponding surface morphologies and properties are described. Most of these surfaces are commercially available and have proven clinical efficacy (>95% over 5 years). The precise role of surface chemistry and topography on the early events in dental implant osseointegration remain poorly understood. In addition, comparative clinical studies with different implant surfaces are rarely performed. The future of dental implantology should aim to develop surfaces with controlled and standardized topography or chemistry. This approach will be the only way to understand the interactions between proteins, cells and tissues, and implant surfaces. The local release of bone stimulating or resorptive drugs in the peri-implant region may also respond to difficult clinical situations with poor bone quality and quantity. These therapeutic strategies should ultimately enhance the osseointegration process of dental implants for their immediate loading and long-term success.

Cylindrical Dental Implants With Hydroxyapatite- and Titanium Plasma Spray–coated Surfaces: 5-year Results

Clinical follow-up was conducted on 127 cylindrical implants placed in 21 patients after 5 years of function: 75 implants were coated with titanium plasma spray (TPS) and 52 implants were coated with hydroxyapatite (HA). The aim of the study was to assess possible differences in clinical function and success rates for each implant type. Clinical and radiographic evaluations were conducted, and the periodontal indices of gingival bleeding, plaque, and calculus were measured. Cumulative data were analyzed for differences by implant type and jaw location. No significant differences were found between the 2 implant systems according to the periodontal parameters studied; however, 5-year success rates were 86.7% for TPS-coated implants and 94.3% for HA-coated implants. The periodontal probe index presented abnormal values in the patients with systemic disease and those who were provisionally restored with single-tooth restorations, complete screw-retained dentures, and fixed partial dentures. There were no differences regarding implant placement when mandibles and maxillae were compared. Long-term success rates were outstanding for HA-coated implants and acceptable for TPS-coated implants after 5 years of function. No significant differences were found between the 2 surfaces.

The influence of implant surface properties on cell adhesion and proliferation

Interactions of the foreign material of implant and the living tissue on the cell level can cause prolonged healing or, worse, loss of the implant. The cell response to the presence of some implant materials was studied under in vitro conditions. The influence of physicochemical surface parameters on the response of the cells in the immediate vicinity of implants, namely on adhesion, proliferation and synthetic activity of fibroblasts, and on the blood coagulation were compared. The direct contact of tested materials (titanium and Ti6Al4V alloy with various surface treatments, Cr Co Mo alloy, hydroxyapatite-coated titanium, zirconium oxide ceramics, polyethylene and carbon composite) on cell spreading was monitored and the presence of TNF-alpha and IL-8 was evaluated in the cultivation medium. The formation of blood clots was investigated on samples immersed in a well with freshly drawn whole rabbit blood using a scanning electron microscope. The surface free energy was estimated using the measurement of static contact angle. Both the advancing and receding contact angles were measured by the dynamic Wilhemy plate method. Two main groups with extremes in cell viability were established. In the first group the increased polar component of surface free energy, the highest cell density, the lowest inflammatory cytokine production, but no fibres in the clotting blood were found. On the contrary, the second group of materials with a very low polar component of the surface free energy showed distinctly higher expression of inflammatory mediators, low cell proliferation, but faster formation of fibres in the blood coagulum.

Histomorphometric evaluation of six dental implant surfaces after early loading in augmented human sinuses

This study investigated the bone-to-implant contact (BIC) and osteoconductive capacity (OC) of 6 different implant surfaces after early loading in humans. Two implants with different surfaces were placed side-by-side in the grafted (n= 5) and nongrafted (n = 1) sinuses of 3 volunteers. Single-tooth restorations were delivered 60 days later. After 6 months of full occlusal loading, implants were retrieved in block sections for histomorphometric analysis. One implant (acid etched) placed in grafted bone failed when loaded. There were no other complications. In grafted bone, the microtextured surface achieved the highest BIC value (94.08%), followed by the oxidized (77.32%), hydroxyapatite (HA) (74.51%), sandblasted and acid-etched (51.85%), and titanium plasma-sprayed (TPS) (41.48%) surfaces. In native bone, the acid-etched surface achieved a higher BIC value (69.03%) than the HA surface (59.03%). The highest OC value in grafted bone was exhibited by the microtextured surface (34.31%), followed by the HA (28.62%), sandblasted and acid-etched (25.08%), oxidized (17.55%), and TPS (-20.47%) surfaces. The HA surface exhibited a higher OC value (30.39%) in native bone compared with the acid-etched surface (24.0%). As a whole, highest BIC and OC values were exhibited by the microtextured surface, and lowest values were exhibited by the TPS surface. All other surfaces demonstrated excellent BIC (>50%) but varied in OC (range = 17.55%-28.62%). These findings are tempered by the limited scope and sample size of the study and should be considered preliminary. More research is needed to determine the impact of implant surface texture on BIC and OC.

Implant surfaces

Available in many shapes, sizes, and lengths, dental implants are also crafted from different materials with different surface proper-ties. Among the most desired characteristics of an implant are those that ensure that the tissue-implant interface will be established quickly and then will be firmly maintained. Because many variables affect oral implants, it is sometimes difficult to reliably predict the likelihood of an implant's success. It is especially difficult to assess whether the various modifications in the latest implants deliver improved performance. This article focuses primarily on important surface characteristics and their potential effects on the performance of dental implants.

A distinguishable observation between survival and success rate outcome of hydroxyapatite-coated implants in 5-10 years in function

PURPOSE

To differentiate between the survival and success definitions of functional hydroxyapatite (HA)-coated implant prosthesis.

METHODS

A total of 248 implants (62 patients), 5-10 years in function, were evaluated. The implant distribution length was 8 mm (6.5%), 10 mm (29.4%), 13 mm (30.2%) and 15 mm (33.9%). The diameter was 3.25 mm (60.1%) and 4 mm (39.9%). Probing depth (PD), gingival index (GI), height of keratinized mucosa (KM) and recession (REC) were measured. Periapical radiographs were taken to estimate the amount of crestal bone resorption (BL), mesially and distally, with the aid of a millimetric-scaled magnifying glass (x 8). Only implants that fulfilled the success rate criteria were considered as successful. All other functional implants were assigned to the non-successful group. All functional implant prostheses were defined as survival ones.

RESULTS

The accumulative survival rate after 5 and 10 years was 94.4% and 92.8%, respectively. Accumulative success rates were 89.9% and 54%, respectively. Implants 13 and 15 mm in length (97.9% and 96.4%, respectively) had the highest survival rate, which was higher over implants 8 and 10 mm in length (75%, P<0.01 and 88.2%, respectively). The survival rate of 4 mm diameter implants compared with 3.25 mm was 96.5% and 90.3%, respectively (P=0.019). The average BL was 1.7, 0.92 and 2.79 mm for the survival, successful and non-successful defined implant groups. PD was 3.26, 2.79 and 4 mm and GI was 0.96, 0.75 and 1.57, respectively. These measurements were statistically different between implant groups. KM and REC measurements showed similar scoring for all groups. A correlation was shown between successful and non-successful implants on the score of GI and PD (P<0.001 in both).

CONCLUSION

A distinguishable observation between survival and success rate was noted particularly in long-term observations. Implant length and diameter have an influence on the survival rate. Clinical parameter scores expressed an influence on the defined implant status.

Influence of alcohol and tobacco habits on peri-implant marginal bone loss: a prospective study

A prospective clinical study was conducted to explore the possible link between peri-implant bone loss and the widespread habits of tobacco smoking and alcohol consumption. One hundred and eighty-five patients who received 514 implants were followed up for 3 years. Peri-implant marginal bone loss was evaluated by digital panoramic radiography and image analysis techniques. Multivariate analysis showed that peri-implant marginal bone loss was significantly related to a daily consumption of >10 g of alcohol, tobacco use and increased plaque levels and gingival inflammation. The present results indicate that daily alcohol consumption and tobacco use may have a negative influence on predictable long-term implant treatment outcomes, producing peri-implant bone loss and compromising restorative treatment with implant-supported prostheses.

Overview of the SwissPlus Implant System

Although many improvements have been made to implant dentistry during the last quarter of a century, clinical challenges still remain. For the surgeon, achieving implant stability in low-density bone can be difficult. For the restorative dentist, incompatibility between implant systems and the increasing complexity of esthetic restorative options frequently require special training in the selection and use of prosthetic components. This article presents an overview of a 1-stage implant system with a textured surface and osteocompressive surgical protocol designed to achieve stability in soft bone. Self-tapping, double lead threads and a separate surgical protocol also enable the implant to be placed in high-density bone. The implant is packaged on a fixture mount that also functions as a transfer and transitional or definitive abutment for cemented restorations. This implant is designed to help simplify restorative procedures by eliminating many ancillary restorative components. For multiple-unit, screw-retained restorations, the prosthesis can be splinted directly to the top of the implant without an intermediate abutment. Overdenture attachments and straight, angled, screw-receiving, and custom-cast abutments complete the restorative system.

Histological evidence of osseointegration in human retrieved fractured hydroxyapatite-coated screw-type implants: a case report

Histological evidence of clinically successful dental implants is very rare. This case report presents histological evidence of osseointegration in human implants retrieved because of fractures at the connected portion between the abutments and fixtures due to a car accident. The duration of functional loading of the implants was 18 months. Two hydroxyapatite (HA)-coated screw-type implants were removed with part of the healthy bone from the mandibular left molar region. A block was prepared using cutting and grinding equipment to obtain a central section approximately 50 microm thick, which was stained with basic fuchsin and methylene blue. Histological examination revealed that the bone was dense and in close relation with the HA coating of the implants. The interspaces of each thread of the implant were filled with mineralized bone. Peri-implant soft tissue was not observed in the section. A high degree of osseointegration was noted, with a bone-to-implant contact of 87.5% (implant corresponding to tooth 36) and 97.4% (implant corresponding to tooth 37). The connection between the 30 and 50 microm HA coating and the metal was uniformly tight and constant. In conclusion, the histological evidence showed a high degree of osseointegration in two HA-coated screw-type dental implants retrieved after functional loading for 18 months.

SwissPlus Implant System, Part 1: Surgical aspects and intersystem comparisons

Implant survival in poor-quality bone continues to pose a significant clinical challenge to dentists. The SwissPlus System comprises one-piece, straight and tapered implant designs with self-tapping, apical threads, and a microtextured surface on the intraosseous portion of the implant bodies. Although both designs are indicated for all ranges of bone density, Tapered SwissPlus features double-lead threads and a soft-bone surgical protocol designed to enhance initial mechanical stability at the time of placement. This paper presents an overview of the SwissPlus System with emphasis on the surgical aspects. Presented test data also illustrate intersystem compatibility and differences between the straight SwissPlus and ITI synOcta implants.