Mineralization at the interface of implants

Comprehensive Overview of Interface Strategies in Implant Osseointegration

With the improvement of implant design and the expansion of application scenarios, orthopedic implants have become a common surgical option for treating fractures and end‐stage osteoarthritis. Their common goal is rapidly forming and long‐term stable osseointegration. However, this fixation effect is limited by implant surface characteristics and peri‐implant bone tissue activity. Therefore, this review summarizes the strategies of interface engineering (osteogenic peptides, growth factors, and metal ions) and treatment methods (porous nanotubes, hydrogel embedding, and other load‐release systems) through research on its biological mechanism, paving the way to achieve the adaptation of both and coordination between different strategies. With the transition of the osseointegration stage, interface engineering strategies have demonstrated varying therapeutic effects. Especially, the activity of osteoblasts runs almost through the entire process of osseointegration, and their physiological activities play a dominant role in bone formation. Furthermore, diseases impacting bone metabolism exacerbate the difficulty of achieving osseointegration. This review aims to assist future research on osseointegration engineering strategies to improve implant‐bone fixation, promote fracture healing, and enhance post‐implantation recovery.

Effect of controlled surface roughness and biomimetic coating on titanium implants adhesion to the bone: An experiment animal study

Introduction

Laser micromachining of titanium and its alloys can create micro-grooves with sizes similar to cell diameter of about 10 μm. Its coating with arginine-glycine-aspartic acid (RGD) may enhance cellular spreading and adhesion. This study aimed to evaluate the effect of laser micro-grooving and laser micro-grooving combined with RGD coating on the strength of the dental implants/bone interface using destructive mechanical pullout testing in experimental animals.

Materials and methods

In this study, the test groups consisted of 1.5-mm diameter, 5-mm long laser-grooved and laser-grooved/RGD coated titanium alloy (Ti-6Al-4 V) rods, and the control group included plain titanium alloy (Ti-6Al-4 V) rods. These rods were implanted in the mandibles of New Zealand white rabbits for 2, 4, and 6 weeks. After sacrifice, the test and control specimens were retrieved for mechanical pullout testing. The DMA 7-e was used to pull the titanium rods out of the bone, the probe position was plotted versus time graph to monitor the test progression, and the static modulus versus time graph was viewed; such graphs was then transformed into tables. The results were analyzed using the Mann-Whitney test.

Results

The laser-grooved/RGD coated rods had significantly higher pull-out strength than the laser-grooved and control rods. Additionally, the laser-grooved rods had significantly higher pull-out strength than control rods.

Conclusion

Two novel surface treatments were used: laser micro-grooving and tri peptide RGD coating, both of which had different effects on the dental implant interface. Laser grooving improved peri-implant bone healing, whereas RGD coating facilitated earlier bone-implant adhesion and better mineralization.

What Does Bone Corticalization around Dental Implants Mean in Light of Ten Years of Follow-Up?

The phenomenon of peri-implant bone corticalization after functional loading does not yet have a definite clinical significance and impact on prognosis. An attempt was made to assess the clinical significance of this phenomenon. This prospective study included 554 patients. Standardized intraoral radiographs documenting the jawbone environment of 1556 implants were collected. The follow-up period was 10 years of functional loading. Marginal alveolar bone loss (MBL) and radiographic bone structure (bone index, BI) were evaluated in relation to intraosseous implant design features and prosthetic work performed. After five years, bone structure abnormalities expressed by a reduction of BI to 0.47 ± 0.21 and MBL = 0.88 ± 1.27 mm were observed. Both values had an inverse relationship with each other (p < 0.0001). Reference cancellous bone showed BI = 0.85 ± 0.18. The same relationship was observed after ten years of functional loading: BI = 0.48 ± 0.21, MBL = 1.49 ± 1.94 mm, and again an inverse relationship (p < 0.0001). Increasing corticalization (lower BI) is strongly associated with increasing marginal bone loss and increasing corticalization precedes future marginal bone loss. Marginal bone loss will increase as corticalization progresses.

Reversible, non‐plaque‐induced marginal bone loss around an osseointegrated implant: A case report

This case report documents a non‐plaque‐induced marginal bone loss around an osseointegrated implant. The loss of osseointegration, most likely caused by overload and/or suboptimal distribution of occlusal loading, may be reversed when the loading is reduced by optimally transmitting stress forces to the implant‐to‐bone interface and surrounding bone.

Limited crestal bone width and a history of ridge augmentation may make peri‐implant supporting bone vulnerable to occlusal overload. In such cases, the prosthetic restoration should be planned with particular focus on reducing and optimizing the occlusal load.

A Parametric Study on a Dental Implant Geometry Influence on Bone Remodelling through a Numerical Algorithm

To ensure the long-term success of a dental implant, it is imperative to understand how chewing loads are transferred through the implant prosthetic components to the surrounding bone tissue. The stress distribution depends on several factors, such as load type, bone–implant interface, shape and materials of the fixture and quality and quantity of the bone. These aspects are of fundamental importance to ensure implant stability and to evaluate the remodelling capacity of the bone tissue to adapt to its biomechanical environment. A bone remodelling algorithm was formulated by the authors and implemented by means of finite element simulations on four different implants with several design characteristics. Internal bone microstructure and density, apposition/resorption of tissue and implant stability were evaluated over a period of 12 months, showing the influence of the geometry on bone tissue evolution over time. Bone remodelling algorithms may be a useful aid for clinicians to prevent possible implant failures and define an adequate implant prosthetic rehabilitation for each patient. In this work, for the first time, external bone remodelling was numerically predicted over time.

Photobiomodulation using LLLT and LED of cells involved in osseointegration and peri-implant soft tissue healing

This study evaluated the influence of photobiomodulation (PBM) using low-level laser therapy (PBM/LLLT) or light-emitting diode (PBM/LED) therapy on peri-implant tissue healing. A laboratory model was used to assess the adhesion and metabolism of osteoblasts (SaOs-2), human gingival fibroblasts (HGF), and normal oral keratinocytes (NOK) seeded on a titanium (Ti) surface. After seeding the cells on disks of Ti placed in wells of 24-well plates, three irradiations were performed every 24 h at energy density of 3 J/cm². For PBM/LLLT, a LaserTABLE device was used with a wavelength of 780 nm and 25 mW, while for PBM/LED irradiation, a LEDTABLE device was used at 810 nm, 20 mW, at a density of 3 J/cm². After irradiations, the number of cells (NC) attached and spread on the Ti surface, cell viability (CV), total protein (TP), and collagen (Col) synthesis were assessed. Alkaline phosphate activity (ALP) was evaluated only for SaOs-2. Data were submitted to ANOVA complemented by Turkey statistical tests at a 5% significance level. PBM significantly increased adherence of NOK to the Ti surface, while no significant effect was observed for SaOs-2 and HGF. PBM positively affected CV, as well as Col and TP synthesis, in distinct patterns according to the cell line. Increased ALP activity was observed only in those cells exposed to PBM/LLLT. Considering cell specificity, this investigation reports that photobiomodulation with low-power laser and LED at determined parameters enhances cellular functions related to peri-implant tissue healing in a laboratory model.

Implant functionalization with mesoporous silica: A promising antibacterial strategy, but does such an implant osseointegrate?

Objectives

New strategies for implant surface functionalization in the prevention of peri‐implantitis while not compromising osseointegration are currently explored. The aim of this in vivo study was to assess the osseointegration of a titanium‐silica composite implant, previously shown to enable controlled release of therapeutic concentrations of chlorhexidine, in the Göttingen mini‐pig oral model.

Material and Methods

Three implant groups were designed: macroporous titanium implants (Ti‐Porous); macroporous titanium implants infiltrated with mesoporous silica (Ti‐Porous + SiO₂); and conventional titanium implants (Ti‐control). Mandibular last premolar and first molar teeth were extracted bilaterally and implants were installed. After 1 month healing, the bone in contact with the implant and the bone regeneration in the peri‐implant gap was evaluated histomorphometrically.

Results

Bone‐to‐implant contact and peri‐implant bone volume for Ti‐Porous versus Ti‐Porous + SiO₂ implants did not differ significantly, but were significantly higher in the Ti‐Control group compared with Ti‐Porous + SiO₂ implants. Functionalization of titanium implants via infiltration of a SiO₂ phase into the titanium macropores does not seem to inhibit implant osseointegration. Yet, the importance of the implant macro‐design, in particular the screw thread design in a marginal gap implant surgery set‐up, was emphasized by the outstanding results of the Ti‐Control implant.

Conclusions

Next‐generation implants made of macroporous Ti infiltrated with mesoporous SiO₂ do not seem to compromise the osseointegration process. Such implant functionalization may be promising for the prevention and treatment of peri‐implantitis given the evidenced potential of mesoporous SiO₂ for controlled drug release.

Influence of Bisphosphonates on the Behavior of Osteoblasts Seeded Onto Titanium Discs

Abstract Among other factors, types of bisphosphonates and treatment regimens seem to be strongly associated with the success or failure of installation of osseointegrated implants. This study investigated the influence of two bisphosphonates, sodium alendronate (SA) and zoledronic acid (ZA), on the metabolism of osteoblasts. Human osteoblasts (Saos-2) were seeded onto machined or acid-treated titanium discs previously placed on 24-well plates in complete culture medium. After 24 h, cells were exposed to bisphosphonates at 0.5, 1 or 5 µM for 24 h, 48 h or 7 days. The effects of SA and ZA on osteoblasts were assessed based on the adhesion of these cells to the titanium surfaces by direct fluorescence, cell viability, total protein and collagen synthesis. Alkaline phosphatase activity and mineral nodule deposition by these cells were also evaluated. Data were evaluated by ANOVA and Tukey tests (α=0.05). Decreased adhesion of cells to the titanium discs was observed when exposed to both bisphosphonates; however, this lack of cell adhesion was more evident for ZA-treated cells. In addition, the exposure of osteoblasts to ZA decreased the viability, ALP activity and mineral nodule deposition, which may be related to poor osseointegration after implant installation.

Effects of occlusal forces on the peri-implant-bone interface stability

The occlusal forces and their influence on the initiation of peri-implant bone loss or their relationship with peri-implantitis have created discussion during the past 30 years given the discrepancies observed in clinical, animal, and finite element analysis studies. Beyond these contradictions, in the case of an osseointegrated implant, the occlusal forces can influence the implant-bone interface and the cells responsible for the bone remodeling in different ways that may result in the maintenance or loss of the osseointegration. This comprehensive review focuses on the information available about the forces transmitted through the implant-crown system to the implant-bone interface and the mechano-transduction phenomena responsible for the bone cells' behavior and their interactions. Knowledge of the basic molecular biology of the peri-implant bone would help clinicians to understand the complex phenomenon of occlusal forces and their effects on the implant-bone interface, and would allow better control of the negative effects of mechanical stresses, leading to therapy with fewer risks and complications.

The determining role of nanoscale mechanical twinning on cellular functions of nanostructured materials

Considering that micromotions generated at the bone-implant interface under physiological loading introduce mechanical strain on the tissue and surface of the implant and that strain can be introduced during processing of the biomedical device, we elucidate here the interplay between mechanically-induced nanoscale twinning in austenitic stainless steel on osteoblast functions. Mechanically-induced nanoscale twinning significantly impacted cell attachment, cell-substrate interactions, proliferation, and subsequent synthesis of prominent proteins (fibronectin, actin, and vinculin). Twinning was beneficial in favorably modulating cellular activity and contributed to small differences in hydrophilicity and nanoscale roughness in relation to the untwinned surface.

Melatonin and periodontal tissues: Molecular and clinical perspectives

Periodontal disease is a frequent chronic inflammatory pathology that implies the destruction of the tissues supporting the teeth, which represents a high sanitary cost. It usually appears associated with other systemic conditions such as diabetes, metabolic syndrome, depression and Alzheimer disease among others. The presence of melatonin and its receptors in the oral cavity supports the hypothesis that this hormone could play a role in homeostasis of periodontal tissues. In the present review we will discuss the potential role of melatonin, a circadian synchronizing hormone, with proved antiinflammatory and antioxidant profile, in the pathogenesis and treatment of periodontitis. Particular emphasis will be placed on the role of the indolamine in the treatment of periodontal disease when this oral condition is comorbid with other pathologies that would also benefit from the therapeutic potential of melatonin and its analogs through diverse mechanisms.

Immediate loading of implants in the edentulous mandible: a multicentre study

PURPOSE

The aim of this prospective study was to investigate the two-year outcomes following immediate loading of mono-cortically engaged implants.

MATERIALS AND METHODS

Thirty healthy mandible edentulous patients with an average age of 67.3 years and presenting with sufficient bony ridge at the mandible symphysis were included in the study. Four Astra Tech, Ti-Oblast^® implants were installed between the mental foramina using the mono-cortical anchorage technique. The primary stability of the implants was assessed by resonance frequency analysis (RFA). After uni-abutments were placed, a temporary bridge was constructed and fixed the same day. The definitive bridges were installed 6 weeks after implant surgery. Five of 120 placed implants were lost in four patients during the first 6 weeks and these patients were excluded from the follow-up. The changes in marginal bone level (n = 20) were evaluated in Brazilian and Swedish groups at baseline, 6 weeks, 6 months, 12 months and 24 months. The RFA (n = 30) was evaluated at baseline, 6 weeks, 6 months, 12 months and 24 months postoperatively.

RESULTS

Compared with baseline measurements, the postoperative values for marginal bone level (6 weeks, 6 months, 12 months and 24 months) were significantly reduced (p < 0.05), while no differences were observed in the RFA analysis (12 months and 24 months).

CONCLUSIONS

The immediate loading of mono-cortically engaged implants in the edentulous mandible is safe and predictable and implant stability remains excellent after 2-year follow-up.

To what extent residual alveolar ridge can be preserved by implant? A systematic review

Background

It has been reported that the load for (or to) implant-supported restoration may lead to bone remodeling as bone resorption and/or formation. While many authors supported the process of bone resorption, others elaborated bone apposition and increasing bone density close and remote to implant body (or fixture). This may suggest the role of the implant to reserve alveolar ridge from physiologic/pathologic resorption. The aim of this systematic review was to predict to how extend dental implants can preserve the residual alveolar ridge based on previous clinical investigations.

Methods

This systematic review based on the retrospective and prospective studies, randomized clinical trial, and case reports. The process of searching for proposed articles included PubMed, Ovid, and Web of Science databases, with specific inclusion and exclusion criterion.

Results

A total 2139 citations were identified. After expunging the repeated articles between databases and application of exclusion and inclusion criteria, 18 articles were found to meet the topic of this systematic review. Many of the articles reported bone preservation with implant-assisted restorations, and the rest denoted noticeable bone apposition.

Conclusion

According to the published clinical studies, the behavior of bone remodeling around implant predicts a sort of residual alveolar bone preservation.

The Effect of Root Coating with Titanium on Prevention of Root Resorption in Avulsed Teeth: An Animal Study

Introduction:

Tooth avulsion is a real dental emergency. If immediate replantation is not performed, the avulsed tooth may be lost due to inflammatory or replacement resorption. This animal study aimed to evaluate the bone response to the titanium coating of the root surface as an artificial barrier, and prevention of resorption of avulsed teeth.

Methods and Materials:

This experimental study was conducted on four male dogs. The dogs were randomly divided into two groups for assessment at two and eight weeks. Four teeth were extracted in each animal. The root surfaces of the test group were coated with a titanium layer using the Electron Beam Deposition system. After 24 h, replantation of the teeth was performed. Two animals were sacrificed after two weeks and the remaining dogs were killed after eight weeks. The presence of inflammation, inflammatory resorption, replacement resorption, periodontal regeneration, periapical granuloma and ankylosis were evaluated through histological analyses.

Results:

Inflammatory root resorption was not present in any tooth except one tooth in the coated group after eight weeks. Replacement resorption was noted just in three of the non-coated teeth after two weeks and two teeth after eight weeks. The McNemar's test revealed that the frequency of replacement resorption in the non-coated group was significantly higher than the coated group (P=0.031).

Conclusion:

Based on the results of this study, it seems that coating the root surfaces of avulsed teeth with titanium may control the replacement root resorption.

Combined microcomputed tomography, biomechanical and histomorphometric analysis of the peri-implant bone: a pilot study in minipig model

OBJECTIVES

To present a practical approach that combines biomechanical tests, microcomputed tomography (μCT) and histomorphometry, providing quantitative results on bone structure and mechanical properties in a minipig model, in order to investigate the specific response to an innovative dental biomaterial.

METHODS

Titanium implants with innovative three-dimensional scaffolds were inserted in the tibias of 4 minipigs. Primary stability and osseointegration were investigated by means of insertion torque (IT) values, resonance frequency analysis (RFA), bone-to-implant contact (BIC), bone mineral density (BMD) and stereological measures of trabecular bone.

RESULTS

A significant positive correlation was found between IT and RFA (r=0.980, p=0.0001). BMD at the implant sites was 18% less than the reference values (p=0.0156). Peri-implant Tb.Th was 50% higher, while Tb.N was 50% lower than the reference zone (p<0.003) and they were negatively correlated (r=-0.897, p=0.006).

SIGNIFICANCE

μCT increases evaluation throughput and offers the possibility for qualitative three-dimensional recording of the bone-implant system as well as for non-destructive evaluation of bone architecture and mineral density, in combination with conventional analysis methods. The proposed multimodal approach allows to improve accuracy and reproducibility for peri-implant bone measurements and could support future investigations.

Clinical and Radiographic Evaluation of Immediate Loaded Dental Implants With Local Application of Melatonin: A Preliminary Randomized Controlled Clinical Trial

Immediate loading of dental implants in situations where low bone density exist, such as the posterior maxillary region, became possible recently after the introduction of biomimetic agents. This 1-year preliminary clinical trial was carried out to clinically and radiographically evaluate immediate-loaded 1-piece implants with local application of melatonin in the osteotomy site as a biomimetic material. 14 patients with missing maxillary premolars were randomized to receive 14 implants of 1-piece type that were subjected to immediate loading after 2 weeks of initial placement. Group I included 7 implants with acid-etched surface while group II included 7 implants with acid-etched surface combined with local application of melatonin gel at the osteotomy site. Patients were recalled for follow up at 1, 3, 6, and 12 months after loading. All implants were considered successful after 12 months of follow-up. Significant difference (P &lt; 0.05) was found between both groups at 1 month of implant loading when considering the implant stability. At 1 and 3 months there were significant differences in the marginal bone level between the 2 groups. These results suggest that the local application of melatonin at the osteotomy site is associated with good stability and minimal bone resorption. However, more studies for longer follow-up periods are required to confirm the effect of melatonin hormone on osseointegration of dental implants.

Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy

The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding-diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments.

Clinical evaluation of anodized surface implants submitted to a counter torque of 25 ncm after 60 days of osseointegration: study in humans

INTRODUCTION

Decreasing the time needed for osseointegration has always been a big challenge for modern implantodontics. The main factor which helps to decrease the time needed for osseointegration is the newly developed surfaces being used, as well as their microstructures, in relation to their osseoinductive properties. The aim of this work is to clinically evaluate the osseointegration of the implants when using The anodized surfaces in humans, following a 60 days-period of osseointegration.

METHODOLOGY

Forty-Five implants were placed in different kinds of bones, according to the technique recommended by the manufacturer. Those implants were opened after 60 days of osseointegration. The success of evaluation was made through assessing the counter torque resistance of 25 Ncm. The implants which could withstand the applied torque were considered osseointegrated.

RESULTS

Of the forty-five implants made in different kinds of bones, only one failed to present osseointegration, resulting in a success rate of 97.7 %.

CONCLUSIONS

With this methodology it was possible to conclude that anodized surface implants present primary osseointegration after 60 days of healing, after which they can function normally.

Atomically resolved tissue integration

In the field of biomedical technology, a critical aspect is the ability to control and understand the integration of an implantable device in living tissue. Despite the technical advances in the development of biomaterials, the elaborate interplay encompassing materials science and biology on the atomic level is not very well understood. Within implantology, anchoring a biomaterial device into bone tissue is termed osseointegration. In the most accepted theory, osseointegration is defined as an interfacial bonding between implant and bone; however, there is lack of experimental evidence to confirm this. Here we show that atom probe tomography can be used to study the implant-tissue interaction, allowing for three-dimensional atomic mapping of the interface region. Interestingly, our analyses demonstrated that direct contact between Ca atoms and the implanted titanium oxide surface is formed without the presence of a protein interlayer, which means that a pure inorganic interface is created, hence giving experimental support to the current theory of osseointegration. We foresee that this result will be of importance in the development of future biomaterials as well as in the design of in vitro evaluation techniques.

Heat and radiofrequency plasma glow discharge pretreatment of a titanium alloy: evidence [corrected] for enhanced osteoinductive properties

It is believed that orthopedic and implant longevity can be improved by optimizing fixation, or direct bone-implant contact, through the stimulation of new bone formation around the implant. The purpose of this study was to determine whether heat (600°C) or radiofrequency plasma glow discharge (RFGD) pretreatment of Ti6Al4V stimulated calcium-phosphate mineral formation in cultures of attached MC3T3 osteoprogenitor cells with or without a fibronectin coating. Calcium-phosphate mineral was analyzed by flame atomic absorption spectrophotometry, scanning electron microscopy (SEM)/electron dispersive X-ray microanalysis (EDAX) and Fourier transformed infrared spectroscopy (FTIR). RFGD and heat pretreatments produced a general pattern of increased total soluble calcium levels, although the effect of heat pretreatment was greater than that of RFGD. SEM/EDAX showed the presence of calcium-and phosphorus-containing particles on untreated and treated disks that were more numerous on fibronectin-coated disks. These particles were observed earliest (1 week) on RFGD-pretreated surfaces. FTIR analyses showed that the heat pretreatment produced a general pattern of increased levels of apatite mineral at 2-4 weeks; a greater effect was observed for fibronectin-coated disks compared to uncoated disks. The observed findings suggest that heat pretreatment of Ti6Al4V increased the total mass of the mineral formed in MC3T3 osteoprogenitor cell cultures more than RFGD while the latter pretreatment hastened the early deposition of mineral. These findings help to support the hypothesis that the pretreatments enhance the osteoinductive properties of the alloy.

Melatonin effects on hard tissues: bone and tooth

Melatonin is an endogenous hormone rhythmically produced in the pineal gland under the control of the suprachiasmatic nucleus (SCN) and the light/dark cycle. This indole plays an important role in many physiological processes including circadian entrainment, blood pressure regulation, seasonal reproduction, ovarian physiology, immune function, etc. Recently, the investigation and applications of melatonin in the hard tissues bone and tooth have received great attention. Melatonin has been investigated relative to bone remolding, osteoporosis, osseointegration of dental implants and dentine formation. In the present review, we discuss the large body of published evidence and review data of melatonin effects on hard tissues, specifically, bone and tooth.

Micromotions and combined damages at the dental implant/bone interface

Micromotion and fretting damages at the dental implant/bone interface are neglected for the limitation of check methods, but it is particularly important for the initial success of osseointegration and the life time of dental implant. This review article describes the scientific documentation of micromotion and fretting damages on the dental implant/bone interface. The fretting amplitude is less than 30 µm in vitro and the damage in the interface is acceptable. While in vivo, the micromotion's effect is the combination of damage in tissue level and the real biological reaction.

Engineering of bone using porous calcium phosphate cement and bone marrow stromal cells for maxillary sinus augmentation with simultaneous implant placement in goats

The aim of this study was to explore the effects of maxillary sinus floor elevation and simultaneous dental implantation with a tissue-engineered bone complex of calcium phosphate cement (CPC) scaffolds combined with bone marrow stromal cells (BMSCs). A large animal goat model is used with the tissue engineering method. Eighteen bilateral maxillary sinus of nine goats were randomly allocated into three groups; the CPC/BMSC complex (n=6) was used to elevate maxillary sinus floor with a simultaneous implant placement; the effects were compared with those treated with CPC alone (n=6) or autogenous bone (n=6). After a healing period of 3 months, sequential triad-color fluorescence labeling, micro-CT, as well as histological and histomorphometric analyses indicated that the tissue-engineered BMSC/CPC complex could promote earlier bone formation and mineralization, and maximally maintain the volume and height of the augmented maxillary sinus. By comparison, CPC-alone or autogenous bone achieved less bone formation and later mineralization. Besides, the average bone-implant contact value reflecting the osseointegration was 35.63%±9.42% in the BMSCs/CPC group, significantly higher than 22.47%±4.28% in the CPC-alone group or 28.26%±8.03% in the autogenous bone group. In conclusion, CPC serves as a potential substrate for BMSCs for the maxillary sinus floor augmentation and simultaneous implantation. The tissue-engineered bone might enhance the stability of implants and thus be of great significance to achieve improved quality to restore the oral function in clinic.

A finite element method approach for the mechanobiological modeling of the osseointegration of a dental implant

The aim of this paper is to introduce a new mathematical model using a mechanobiological approach describing the process of osseointegration at the bone-dental implant interface in terms of biological and mechanical factors and the implant surface. The model has been computationally implemented by using the finite element method. The results show the spatial-temporal patterns distribution at the bone-dental implant interface and demonstrate the ability of the model to reproduce features of the wound healing process such as blood clotting, osteogenic cell migration, granulation tissue formation, collagen-like matrix displacements and new osteoid formation. The model might be used as a methodological basis for designing a dental tool useful to predict the degree of osseointegration of dental implants and subsequent formulation of mathematical models associated with different types of bone injuries and different types of implantable devices.

Gene expression dynamics during bone healing and osseointegration

BACKGROUND

Understanding the molecular features of bone repair and osseointegration may aid in the development of therapeutics to improve implant outcomes. The purpose of this investigation is to determine the gene expression dynamics during alveolar bone repair and implant osseointegration.

METHODS

An implant osseointegration preclinical animal model was used whereby maxillary defects were created at the time of oral implant placement, while a tooth extraction socket healing model was established on the contralateral side of each animal. The surrounding tissues in the zone of the healing defects were harvested during regeneration for temporal evaluation using histology, immunohistochemistry, laser capture microdissection, and quantitative reverse transcription-polymerase chain reaction for the identification of a panel of 17 putative genes associated with wound repair.

RESULTS

In both models, three distinct expression patterns were displayed: 1) genes that are slowly increased during the healing process, such as bone morphogenetic protein 4, runt-related transcription factor 2, and osteocalcin; 2) genes that are upregulated at the early stage of healing and then downregulated at later stages, such as interleukin and chemokine (C-X-C motif) ligands 2 and 5; and 3) genes that are constitutively expressed over time, such as scleraxis. Although some similarities between osseointegration and tooth extraction socket were seen, distinct features developed and triggered a characteristic coordinated expression and orchestration of transcription factors, growth factors, extracellular matrix molecules, and chemokines.

CONCLUSIONS

Characterization of these events contributes to a better understanding of cooperative molecular dynamics in alveolar bone healing, and highlights potential pathways that could be further explored for the enhancement of osseous regenerative strategies.

Evaluation of functional dynamics during osseointegration and regeneration associated with oral implants

OBJECTIVES

The aim of this paper is to review current investigations on functional assessments of osseointegration and assess correlations to the peri-implant structure.

MATERIAL AND METHODS

The literature was electronically searched for studies of promoting dental implant osseointegration, functional assessments of implant stability, and finite element (FE) analyses in the field of implant dentistry, and any references regarding biological events during osseointegration were also cited as background information.

RESULTS

Osseointegration involves a cascade of protein and cell apposition, vascular invasion, de novo bone formation and maturation to achieve the primary and secondary dental implant stability. This process may be accelerated by alteration of the implant surface roughness, developing a biomimetric interface, or local delivery of growth-promoting factors. The current available pre-clinical and clinical biomechanical assessments demonstrated a variety of correlations to the peri-implant structural parameters, and functionally integrated peri-implant structure through FE optimization can offer strong correlation to the interfacial biomechanics.

CONCLUSIONS

The progression of osseointegration may be accelerated by alteration of the implant interface as well as growth factor applications, and functional integration of peri-implant structure may be feasible to predict the implant function during osseointegration. More research in this field is still needed.

Porous bioactive nanostructured scaffolds for bone regeneration: a sol-gel solution

Considerable advances have been seen in materials with tailored nanostructures in recent years, owing, in part, to increased demands placed on material properties in fields, such as tissue regeneration and wound healing. This review focuses on the developments made in nanoporous bioactive glasses, their novel nanocomposites and their application to bone regeneration. Bioactive glasses have the ability to stimulate new bone growth as they dissolve in the body. Sol-gel bioactive glasses have a nanoporosity that provides sites for cell attachment and tailorable degradation rates. Importantly, the glasses can be made into interconnected porous structures that can be used as 3D templates for bone growth, although, because they are glasses, they cannot be implanted directly into sites that are under cyclic loading. Composites provide a partial solution to this problem, although their bioactive and degradation properties are not ideal, therefore novel nanocomposites are needed. The route to these potentially ideal materials is described.

Estimation of the specific surface area of apatites in human mineralized tissues using 31P MAS NMR

Specific surface areas of apatites in whole human mineralized tissues were estimated from (31)P MAS NMR linewidths: 77 m(2)g(-1) for enamel and 94 m(2)g(-1) for dentin, dental cementum and cortical bone.

New paradigm in implant osseointegration

During the last years, implant dentistry has seen an dramatic increase as a treatment option in oral rehabilitation. This is based to a large extent on scientific advances and clinical improvements in implantology. The extension of indications has broadened the opprtunities to rehabilitate patients that were formerly considered to posess restricted indications to place implants. Additionally, patient desires (high aesthetic demands, fast prosthetic rehabilitation) were placed more in focus, resulting in new approaches in implant dentistry. As a result, the scientific and clinical community has reached high standards and at the same time has founded the basis for new opportunities in implantology. The advances are mirrored by a high number of high quality scientific papers, published in conventional and open-access journals. A major shift has thereby been observed in the understanding of implant healing, leading the basis for new implant systems that allow fast rehabilitation protocols. The term ossseointegration needs a new understanding since an immediate osseointegration state can be present under distinct conditions.