The in vivo effect of P-15 coating on early osseointegration

Addressing Antimicrobial Properties in Guided Tissue/Bone Regeneration Membrane: Enhancing Effectiveness in Periodontitis Treatment

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are the two surgical techniques generally used for periodontitis disease treatment. These techniques are based on a barrier membrane to direct the growth of new bone and gingival tissue at sites with insufficient volumes or dimensions of bone or gingiva for proper function, esthetics, or prosthetic restoration. Numerous studies have highlighted biocompatibility, space-creation, cell-blocking, bioactivity, and proper handling as essential characteristics of a membrane's performance. Given that bacterial infection is the primary cause of periodontitis, we strongly believe that addressing the antimicrobial properties of these membranes is of utmost importance. Indeed, the absence of effective inhibition of periodontal pathogens has been recognized as a primary factor contributing to the failure of GTR/GBR membranes. Therefore, we suggest considering antimicrobial properties as one of the key factors in the design of GTR/GBR membranes. Antibiotics are potent medications frequently administered systemically to combat microbes and mitigate bacterial infections. Nevertheless, the excessive use of antibiotics has resulted in a surge in bacterial resistance. To overcome this challenge, alternative antibacterial substances have been developed. In this review, we explore the utilization of alternative substances with antimicrobial properties for topical application in membranes. The use of antibacterial nanoparticles, phytochemical compounds, and antimicrobial peptides in this context was investigated. By carefully selecting and integrating antimicrobial agents into GTR/GBR membranes, we can significantly enhance their effectiveness in combating periodontitis. These antibacterial substances not only act as barriers against pathogenic bacteria but also promote the process of periodontal healing.

Osseointegration of implant surfaces in metabolic syndrome and type-2 diabetes mellitus

This in vivo study evaluated the bone healing response around endosteal implants with varying surface topography/chemistry in a preclinical, large transitional model induced with metabolic syndrome (MS) and type-2 diabetes mellitus (T2DM). Fifteen Göttingen minipigs were randomly distributed into two groups: (i) control (normal diet, n = 5) and (ii) O/MS (cafeteria diet for obesity induction, n = 10). Following obesity induction, five minipigs from the obese/metabolic syndrome (O/MS) group were further allocated, randomly, into the third experimental group: (iii) T2DM (cafeteria diet + streptozotocin). Implants with different surface topography/chemistry: (i) dual acid-etched (DAE) and (ii) nano-hydroxyapatite coating over the DAE surface (NANO), were placed into the right ilium of the subjects and allowed to heal for 4 weeks. Histomorphometric evaluation of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO) within implant threads were performed using histomicrographs. Implants with NANO surface presented significantly higher %BIC (~26%) and %BAFO (~35%) relative to implants with DAE surface (%BIC = ~14% and %BAFO = ~28%, p < .025). Data as a function of systemic condition presented significantly higher %BIC (~28%) and %BAFO (~42%) in the control group compared with the metabolically compromised groups (O/MS: %BIC = 14.35% and %BAFO = 26.24%, p < .021; T2DM: %BIC = 17.91% and %BAFO = 26.12%, p < .021) with no significant difference between O/MS and T2DM (p > .05). Statistical evaluation considering both factors demonstrated significantly higher %BIC and %BAFO for the NANO surface relative to DAE implant, independent of systemic condition (p < .05). The gain increase of %BIC and %BAFO for the NANO compared with DAE was more pronounced in O/MS and T2DM subjects. Osseointegration parameters were significantly reduced in metabolically compromised subjects compared with healthy subjects. Nanostructured hydroxyapatite-coated surfaces improved osseointegration relative to DAE, regardless of systemic condition.

Bone healing around implants placed in subjects with metabolically compromised systemic conditions

The aim of this study was to evaluate the bone healing of tight-fit implants placed in the maxilla and mandible of subjects compromised with metabolic syndrome (MS) and type-2 Diabetes Mellitus (T2DM). Eighteen Göttingen minipigs were randomly distributed into three groups: (i) control (normal diet), (ii) MS (cafeteria diet for obesity induction), (iii) T2DM (cafeteria diet for obesity induction + Streptozotocin for T2DM induction). Maxillary and mandibular premolars and molar were extracted. After 8 weeks of healing, implants with progressive small buttress threads were placed, and allowed to integrate for 6 weeks after which the implant/bone blocks were retrieved for histological processing. Qualitative and quantitative histomorphometric analyses (percentage of bone-to-implant contact, %BIC, and bone area fraction occupancy within implant threads, %BAFO) were performed. The bone healing process around the implant occurred predominantly through interfacial remodeling with subsequent bone apposition. Data as a function of systemic condition yielded significantly higher %BIC and %BAFO values for healthy and MS relative to T2DM. Data as a function of maxilla and mandible did not yield significant differences for either %BIC and %BAFO. When considering both factors, healthy and MS subjects had %BIC and %BAFO trend towards higher values in the mandible relative to maxilla, whereas T2DM yielded higher %BIC and %BAFO in the maxilla relative to mandible. All systemic conditions presented comparable levels of %BIC and %BAFO in the maxilla; healthy and MS presented significantly higher %BIC and %BAFO relative to T2DM in the mandible. T2DM presented lower amounts of bone formation around implants relative to MS and healthy. Implants placed in the maxilla and in the mandible showed comparable amounts of bone in proximity to implants.

Recent advances in design and applications of biomimetic self-assembled peptide hydrogels for hard tissue regeneration

Abstract

The development of natural biomaterials applied for hard tissue repair and regeneration is of great importance, especially in societies with a large elderly population. Self-assembled peptide hydrogels are a new generation of biomaterials that provide excellent biocompatibility, tunable mechanical stability, injectability, trigger capability, lack of immunogenic reactions, and the ability to load cells and active pharmaceutical agents for tissue regeneration. Peptide-based hydrogels are ideal templates for the deposition of hydroxyapatite crystals, which can mimic the extracellular matrix. Thus, peptide-based hydrogels enhance hard tissue repair and regeneration compared to conventional methods. This review presents three major self-assembled peptide hydrogels with potential application for bone and dental tissue regeneration, including ionic self-complementary peptides, amphiphilic (surfactant-like) peptides, and triple-helix (collagen-like) peptides. Special attention is given to the main bioactive peptides, the role and importance of self-assembled peptide hydrogels, and a brief overview on molecular simulation of self-assembled peptide hydrogels applied for bone and dental tissue engineering and regeneration.

Graphic abstract

The multifaceted roles of antimicrobial peptides in oral diseases

Antimicrobial peptides are naturally occurring protein molecules with antibacterial, antiviral and/or antifungal activity. Some antimicrobial peptides kill microorganisms through direct binding with negatively charged microbial surfaces. This action disrupts the cytoplasmic membrane and leads to the leakage of the cytoplasm. In addition, they are involved in the innate immune response. Antimicrobial peptides play an important role in oral health, as natural antimicrobial peptides are the first line of host defence in response to microbial infection. The level of natural antimicrobial peptides increases during severe disease conditions and play a role in promoting the healing of oral tissues. However, they are insufficient for eliminating pathogenic micro-organisms. The variability of the oral environment can markedly reduce the effect of natural antimicrobial peptides. Thus, researchers are developing synthetic antimicrobial peptides with promising stability and biocompatibility. Synthetic antimicrobial peptides are a potential alternative to traditional antimicrobial therapy. Pertinent to oral diseases, the deregulation of antimicrobial peptides is involved in the pathogenesis of dental caries, periodontal disease, mucosal disease and oral cancer, where they can kill pathogenic microorganisms, promote tissue healing, serve as biomarkers and inhibit tumor cells. This narrative review provides an overview of the multifaceted roles of antimicrobial peptides in oral diseases.

Histological and Nanomechanical Properties of a New Nanometric Hydroxiapatite Implant Surface. An In Vivo Study in Diabetic Rats

Implant therapy is a predictable treatment to replace missing teeth. However, the osseointegration process may be negatively influenced by systemic conditions, such as diabetes mellitus (DM). Microtopography and implant surface developments are strategies associated to better bone repair. This study aimed to evaluate, in healthy and diabetic rats, histomorphometric (bone to implant contact = %BIC; and bone area fraction occupancy = %BAFO) and nanomechanical (elastic modulus = EM; and hardness = H) bone parameters, in response to a nanometric hydroxyapatite implant surface. Mini implants (machined = MAC; double acid etched = DAE, and with addition of nano-hydroxyapatite = NANO) were installed in tibias of healthy and diabetic rats. The animals were euthanized at 7 and 30 days. NANO surface presented higher %BIC and %BAFO when compared to MAC and DAE (data evaluated as a function of implant surface). NANO surface presented higher %BIC and %BAFO, with statistically significant differences (data as a function of time and implant surface). NANO surface depicted higher EM and H values, when compared to machined and DAE surfaces (data as a function of time and implant surface). Nano-hydroxyapatite coated implants presented promising biomechanical results and could be an important tool to compensate impaired bone healing reported in diabetics.

Clinical, histological, and nanomechanical parameters of implants placed in healthy and metabolically compromised patients

OBJECTIVES

To evaluate the clinical outcomes, histological parameters, and bone nanomechanical properties around implants retrieved from healthy and metabolic syndrome (MS) patients.

METHODS

Twenty-four patients with edentulous mandibles (12/condition), received four implants between the mental foramina. An additional implant prototype was placed for retrieval histology. The following clinical outcomes were evaluated: insertion torque (IT), implant stability quotient (ISQ) values at baseline and after 60 days of healing, and implant survival. The prototype was retrieved after the healing and histologically processed for bone morphometric evaluation of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO), and bone nanoindentation to determine the elastic modulus (Em) and hardness (H). Descriptive statistical procedures and survival tests were used to analyze the data.

RESULTS

The final study population was comprised of 10 women and 11 men (∼64 years). A total of 105 implants were placed, 21 retrieved for histology. Implant survival rates were similar between groups (>99 %). Similarly, IT and ISQ analyses showed no significant association with systemic condition (p > 0.216). Histological micrographs depicted similar bone morphology, woven bone, for both conditions. While MS (33 ± 5.3 %) and healthy (39 ± 6.5 %) individuals showed no significant difference for %BIC (p = 0.116), significantly higher %BAFO was observed for healthy (45 ± 4.6 %) relative to MS (30 ± 3.8 %) (p < 0.001). No significant differences on bone nanomechanical properties was observed (p > 0.804).

CONCLUSIONS

Although no significant influence on clinical parameters and bone nanomechanical properties was observed, MS significantly reduced bone formation in the peri-implant area in the short-term.

CLINICAL SIGNIFICANCE

A lower amount of bone formation in the peri-implant area was observed in comparison to healthy patients, although the other short-term clinical outcomes were not significantly different. Considering the escalating prevalence of MS patients in need for implant treatment, it becomes crucial to understand bone-to-implant response to determine the ideal loading time in this population.

A collagen telopeptide binding peptide shows potential in aiding collagen bundle formation and fibril orientation

A double-armed CTBP-PEG-CTBP derivative of a collagen telopeptide binding peptide (CTBP), shows potential in aiding collagen bundle formation and fibril orientation by interacting with fibrils.

Peptides for bone tissue engineering

Molecular signals in the form of growth factors are the main modulators of cell behavior. However, the use of growth factors in tissue engineering has several drawbacks, including their costs, difficult production, immunogenicity and short half-life. Furthermore, many of them are pleiotropic and, since a single growth factor can have different active domains, their effect is not always fully controllable. A very interesting alternative that has recently emerged is the use of biomimetic peptides. Sequences derived from the active domains of soluble or extracellular matrix proteins can be used to functionalize the biomaterials used as scaffolds for new tissue growth to either direct the attachment of cells or to be released as soluble ligands. Since these short peptides can be easily designed and cost-effectively synthesized in vitro, their use has opened up a world of new opportunities to obtain cheaper and more effective implants for regenerative medicine strategies. In this extensive review we will go through many of the most important peptides with potential interest for bone tissue engineering, not limiting to those that only mediate cell adhesion or induce the osteogenic differentiation of progenitor cells, but also focusing on those that direct angiogenesis because of its close relation with bone formation.

Microrobotized blasting improves the bone-to-textured implant response. A preclinical in vivo biomechanical study

This study evaluated the effect of microrobotized blasting of titanium endosteal implants relative to their manually blasted counterparts. Two different implant systems were utilized presenting two different implant surfaces. Control surfaces (Manual) were fabricated by manually grit blasting the implant surfaces while experimental surfaces (Microblasted) were fabricated through a microrobotized system that provided a one pass grit blasting routine. Both surfaces were created with the same ~50µm average particle size alumina powder at ~310KPa. Surfaces were then etched with 37% HCl for 20min, washed, and packaged through standard industry procedures. The surfaces were characterized through scanning electron microscopy (SEM) and optical interferometry, and were then placed in a beagle dog radius model remaining in vivo for 3 and 6 weeks. The implant removal torque was recorded and statistical analysis evaluated implant system and surface type torque levels as a function of time in vivo. Histologic sections were qualitatively evaluated for tissue response. Electron microscopy depicted textured surfaces for both manual and microblasted surfaces. Optical interferometry showed significantly higher Sa, Sq, values for the microblasted surface and no significant difference for Sds and Sdr values between surfaces. In vivo results depicted that statistically significant gains in biomechanical fixation were obtained for both implant systems tested at 6 weeks in vivo, while only one system presented significant biomechanical gain at 3 weeks. Histologic sections showed qualitative higher amounts of new bone forming around microblasted implants relative to the manually blasted group. Microrobotized blasting resulted in higher biomechanical fixation of endosteal dental implants and should be considered as an alternative for impant surface manufacturing.

In vivo evaluation of biofunctionalized implant surfaces with a synthetic peptide (P-15) and its impact on osseointegration. A preclinical animal study

OBJECTIVES

The overall aim of the study was to investigate a biofunctionalized implant surface with electrochemically deposition of hydroxyapatite and the synthetic peptide (P-15) and its effect on osseointegration.

MATERIAL AND METHODS

Three modified implant types of ANKYLOS^® C/X implants were used; (1) machined implants used as negative control (M, n = 20), (2) implants with the FRIADENT^® plus surface (grit blasted and acid-etched) used as positive control (P, n = 20), and (3) implants with a biomimetic surface consisting of hydroxyapatite and the synthetic 15 aminoacids containing peptide P-15 (BP, n = 40). The implants were randomly inserted in the mandibles of 10 beagle dogs following 4 months after tooth extraction (P1-P4). Three animals were sacrificed 2 and 7 days after implant insertion, respectively, and four animals were sacrificed 6 months post implant insertion. Bone-to-implant contacts (BICs) were analyzed via histomorphometrical analyses at five different region of interests (ROIs); two at the middle part on either side of the implant (ROI 1/4), two at the apical part of the implant at each side (ROI 2/3), and one at the tip of the implant (ROI 5).

RESULTS

All implant surfaces showed a high level of osseointegration and osteoconductivity. The cumulative implant survival rate (CSR) was 93.8%, 100% in the M, 85% in the P, and 95% in the BP group. No statistical difference in BICs at ROI 1/4, 2/3, and 5 could be shown between implant types following 2 and 7 days of healing. BIC values increased in all groups over time. After 6 months of healing the BP group showed superiority in BIC in ROI 2/3 (73.2 ± 15.6%) compared to the P (48.3 ± 10.6%) and M group (66.3 ± 30.2%) with a significant difference between BP and P (P = 0.002).

CONCLUSION

It is hypothesized, that the surface biofunctionalization improves peri-implant bone formation and remodeling, leading to an increased bone-to implant contact. However, within the limitations of the study set-up no benefit in the early phase of osseointegration could be established for dental implants with P-15 containing surface in this study.

Calcium phosphate nanocoatings and nanocomposites, part I: recent developments and advancements in tissue engineering and bioimaging

A number of materials have been applied as implant coatings and as tissue regeneration materials. Calcium phosphate holds a special consideration, due to its chemical similarity to human bone and, most importantly, its dissolution characteristics, which allow for bone growth and regeneration. The applications of molecular and nanoscale-based biological materials have been and will continue to play an ever increasing role in enhancing and improving the osseointegration of dental and orthopedic implants. More recently, extensive research efforts have been focused on the development and applications of fluorescent nanoparticles and nanocoatings for in vivo imaging and diagnostics as well as devising methods of adding luminescent or fluorescent capabilities to enhance the in vivo functionality of calcium phosphate-based biomedical materials.

Osseointegration: hierarchical designing encompassing the macrometer, micrometer, and nanometer length scales

OBJECTIVE

Osseointegration has been a proven concept in implant dentistry and orthopedics for decades. Substantial efforts for engineering implants for reduced treatment time frames have focused on micrometer and most recently on nanometer length scale alterations with negligible attention devoted to the effect of both macrometer design alterations and surgical instrumentation on osseointegration. This manuscript revisits osseointegration addressing the individual and combined role of alterations on the macrometer, micrometer, and nanometer length scales on the basis of cell culture, preclinical in vivo studies, and clinical evidence.

METHODS

A critical appraisal of the literature was performed regarding the impact of dental implant designing on osseointegration. Results from studies with different methodological approaches and the commonly observed inconsistencies are discussed.

RESULTS

It is a consensus that implant surface topographical and chemical alterations can hasten osseointegration. However, the tailored combination between multiple length scale design parameters that provides maximal host response is yet to be determined.

SIGNIFICANCE

In spite of the overabundant literature on osseointegration, a proportional inconsistency in findings hitherto encountered warrants a call for appropriate multivariable study designing to ensure that adequate data collection will enable osseointegration maximization and/or optimization, which will possibly lead to the engineering of endosteal implant designs that can be immediately placed/loaded regardless of patient dependent conditions.