Hard and soft tissue healing around teeth prepared with the biologically oriented preparation technique and restored with provisional crowns: An in vivo experimental investigation.

AIM: To evaluate the hard and soft tissues healing around teeth prepared with the biologically oriented preparation technique (BOPT) versus the chamfer technique versus non-prepared teeth. MATERIALS AND METHODS: Thirty-two teeth in eight beagle dogs were randomly prepared with the BOPT (test = 16) or chamfer (control = 16) techniques and covered with polymethylmethacrylate crowns as provisional restorations. Sixteen negative controls (non-prepared teeth) were also used for comparison. Histological description and histomorphometrical measurements of the periodontal tissues were collected at 4 and 12 weeks in 7 out of 8 dogs, including the soft tissue height and thickness, and the horizontal and vertical bone dimensions. RESULTS: When compared with negative controls, test and control preparation techniques exhibited a more apical location of the free gingival margin with respect to the cement-enamel junction (∆ = 1.1 mm for both groups at 4 weeks (p < .05), 0.99 mm for the test group (p = .043) and 0.20 mm for control group (p = 1.000) at 12 weeks). There were no significant differences between test and control groups with respect to vertical and horizontal histometric measurements. CONCLUSIONS: The BOPT and chamfer tooth preparation protocols induced similar qualitative and quantitative changes in the healing of the supra-crestal soft tissue complex, when compared with non-prepared teeth. Despite the limited amount of power, it appeared that differences between the tested preparation techniques were not statistically significant.

In Vitro Monitoring of Magnesium-Based Implants Degradation by Surface Analysis and Optical Spectroscopy.

Magnesium (Mg)-based degradable alloys have attracted substantial attention for tissue engineering applications due to their biodegradability and potential for avoiding secondary removal surgeries. However, insufficient data in the existing literature regarding Mg's corrosion and gas formation after implantation have delayed its wide clinical application. Since the surface properties of degradable materials constantly change after contact with body fluid, monitoring the behaviour of Mg in phantoms or buffer solutions could provide some information about its physicochemical surface changes over time. Through surface analysis and spectroscopic analysis, we aimed to investigate the structural and functional properties of degradable disks. Since bubble formation may lead to inflammation and change pH, monitoring components related to acidosis near the cells is essential. To study the bubble formation in cell culture media, we used a newly developed Mg alloy (based on Mg, zinc, and calcium), pure Mg, and commercially available grade 2 Titanium (Ti) disks in Dulbecco's Modified Eagle Medium (DMEM) solution to observe their behaviour over ten days of immersion. Using surface analysis and the information from near-infrared spectroscopy (NIRS), we concluded on the conditions associated with the medical risks of Mg alloy disintegration. NIRS is used to investigate the degradation behaviour of Mg-based disks in the cell culture media, which is correlated with the surface analysis where possible.

Hard and soft tissue healing around implants with a modified implant neck configuration: An experimental in vivo preclinical investigation.

OBJECTIVES: Evaluate the dimensions and morphology of peri-implant tissues around a modified dental implant designed with tissue level connection and a convergent transmucosal neck, when compared with a conventional bone level implant connected to a cylindrical machined titanium abutment. MATERIAL AND METHODS: Eight experimental animals were used for this in vivo investigation, in whom 16 test and 16 control implants were placed following a random allocation sequence. The following histological outcomes at 4 and 12 weeks were evaluated: morphology of peri-implant tissues, the soft tissue height and thickness, the horizontal and vertical bone remodeling, and the bone to implant contact (BIC). RESULTS: In both early (4 weeks) and late (12 weeks) healing times, there were no statistically significant differences between test and control implants, with respect to the overall height and thickness of the peri-implant hard and soft tissues. There was a tendency toward a more coronal free gingival margin (I-FGM) at the buccal aspect of test when compared to control implants (at 4 weeks, difference of 0.97 mm (p = .572) and 0.30 mm (p = 1.000) at 12 weeks). Similarly, there was a tendency toward a more coronal position of the first bone to implant contact (I-B) at the buccal aspect of test as compared to control implants (1.08 mm (p = 0.174) at 4 weeks and 0.83 mm (p = 0.724) at 12 weeks). CONCLUSIONS: Hard and soft tissue healing occurred at both implant types with no statistically significant differences. Test implants tended to present a more coronal gingival margin (FGM) and first bone to implant contact (B).

Biological responses to physicochemical properties of biomaterial surface.

Biomedical scientists use chemistry-driven processes found in nature as an inspiration to design biomaterials as promising diagnostic tools, therapeutic solutions, or tissue substitutes. While substantial consideration is devoted to the design and validation of biomaterials, the nature of their interactions with the surrounding biological microenvironment is commonly neglected. This gap of knowledge could be owing to our poor understanding of biochemical signaling pathways, lack of reliable techniques for designing biomaterials with optimal physicochemical properties, and/or poor stability of biomaterial properties after implantation. The success of host responses to biomaterials, known as biocompatibility, depends on chemical principles as the root of both cell signaling pathways in the body and how the biomaterial surface is designed. Most of the current review papers have discussed chemical engineering and biological principles of designing biomaterials as separate topics, which has resulted in neglecting the main role of chemistry in this field. In this review, we discuss biocompatibility in the context of chemistry, what it is and how to assess it, while describing contributions from both biochemical cues and biomaterials as well as the means of harmonizing them. We address both biochemical signal-transduction pathways and engineering principles of designing a biomaterial with an emphasis on its surface physicochemistry. As we aim to show the role of chemistry in the crosstalk between the surface physicochemical properties and body responses, we concisely highlight the main biochemical signal-transduction pathways involved in the biocompatibility complex. Finally, we discuss the progress and challenges associated with the current strategies used for improving the chemical and physical interactions between cells and biomaterial surface.

Biocompatibility of alumina-based biomaterials-A review.

In today's medicine world, alumina-based biomaterials owing to their excellent biomechanical, and biocompatibility properties play a key role in biomedical engineering. However, the literature still suffers from not having a valid database regarding the protein adsorption and subsequently cell responses to these surfaces. Proteins by adsorption on biomaterials surfaces start interpreting the construction and also arranging the biomaterials surfaces into a biological language. Hence, the main concentration of this review is on the protein adsorption and subsequently cell responses to alumina's surface, which has a wide range biomedical applications, especially in dentistry and orthopedic applications. In the presented review article, the general principles of foreign body response mechanisms, and also the role of adsorbed proteins as key players in starting interactions between cells and alumina-based biomaterials will be discussed in detail. In addition, the essential physicochemical, and mechanical properties of alumina surfaces which significantly impact on proteins and cells responses as well as the recent studies that have focused on the biocompatibility of alumina will be given. An in depth understanding of how the immune system interacts with the surface of alumina could prove the pivotal importance of the biocompatibility of alumina on its success in tissue engineering after implantation in body.

Bioengineered Scaffolds for Stem Cell Applications in Tissue Engineering and Regenerative Medicine.

Stem cell-based therapies, harnessing the ability of stem cells to regenerate damaged or diseased tissues, are under wide-ranging consideration for regenerative medicine applications. However, limitations concerning poor cell persistence and engraftment upon cell transplantation still remain. During the recent years, several types of biomaterials have been investigated to control the fate of the transplanted stem cells, aiming to increase their therapeutic efficiency. In the present chapter we focus on the general properties of some of these biomaterials, which include polymers, ceramics, and nano-biomaterials. In the first part of the chapter, a brief explanation about stem cell biology, sources, and their microenvironment is provided. The second part of the chapter presents some of the most recent studies investigating different types of biomaterials and approaches that aim to mimic the stem cell microenvironment for a more precise control of the stem cell fate.

Biomaterials for Regenerative Medicine: Historical Perspectives and Current Trends.

Biomaterials are key components in tissue engineering and regenerative medicine applications, with the intended purpose of reducing the burden of disease and enhancing the quality of life of a large number of patients. The success of many regenerative medicine strategies, such as cell-based therapies, artificial organs, and engineered living tissues, is highly dependent on the ability to design or produce suitable biomaterials that can support and guide cells during tissue healing and remodelling processes. This chapter presents an overview about basic research concerning the use of different biomaterials for tissue engineering and regenerative medicine applications. Starting from a historical perspective, the chapter introduces the basic principles of designing biomaterials for tissue regeneration approaches. The main focus is set on describing the main classes of biomaterials that have been applied in regenerative medicine, including natural and synthetic polymers, bioactive ceramics, and composites. For each class of biomaterials, some of the most important physicochemical and biological properties are presented. Finally, some challenges and concerns that remain in this field are presented and discussed.

Immunohistochemical comparison of lateral bone augmentation using a synthetic TiO2 block or a xenogeneic graft in chronic alveolar defects.

OBJECTIVES: To evaluate osteogenic markers and alveolar ridge profile changes in guided bone regeneration (GBR) of chronic noncontained bone defects using a nonresorbable TiO2 block. MATERIALS AND METHODS: Three buccal bone defects were created in each hemimandible of eight beagle dogs and allowed to heal for 8 weeks before GBR. Treatment was assigned by block randomization: TiO2 block: TiO2 -scaffold and a collagen membrane, DBBM particulates: Deproteinized bovine bone mineral (DBBM) and a collagen membrane, Empty control: Only collagen membrane. Bone regeneration was assessed on two different healing timepoints: early (4 weeks) and late healing (12 weeks) using several immunohistochemistry markers including alpha-smooth muscle actin (α-SMA), osteopontin, osteocalcin, tartrate-resistant acid phosphatase, and collagen type I. Histomorphometry was performed on Movat Pentachrome-stained and Von Kossa/Van Gieson-stained sections. Stereolithographic (STL) models were used to compare alveolar profile changes. RESULTS: The percentage of α-SMA and osteopontin increased in TiO2 group after 12 weeks of healing at the bone-scaffold interface, while collagen type I increased in the empty control group. In the defect area, α-SMA decreased in the empty control group, while collagen type I increased in the DBBM group. All groups maintained alveolar profile from 4 to 12 weeks, but TiO2 group demonstrated the widest soft tissue contour profile. CONCLUSIONS: The present findings suggested contact osteogenesis when GBR is performed with a TiO2 block or DBBM particulates. The increase in osteopontin indicated a potential for bone formation beyond 12 weeks. The alveolar profile data indicated a sustained lateral increase in lateral bone augmentation using a TiO2 block and a collagen membrane, as compared with DBBM and a collagen membrane or a collagen membrane alone.

Selective Contribution of Bioactive Glasses to Molecular and Cellular Pathways.

Over the past few decades, biomedical scientists and surgeons have given substantial attention to bioactive glasses as promising, long-lasting biomaterials that can make chemical connections with the neighboring hard and soft tissues. Several studies have examined the cellular and molecular responses to bioactive glasses to determine if they are suitable biomaterials for tissue engineering and regenerative medicine. In this regard, different ions and additives have been used recently to induce specific characteristics for selective cellular and molecular responses. This Review briefly describes foreign-body response mechanisms and the role of adsorbed proteins as the key players in starting interactions between cells and biomaterials. It then explains the physicochemical properties of the most common bioactive glasses, which have a significant impact on their cellular and molecular responses. It is expected that, with the development of novel strategies, the physiochemical properties of bioactive glasses can be engineered to precisely control proteins' adsorption and cellular functions after implantation.

Coating doxycycline on titanium-based implants: Two in vivo studies.

Regardless of the substantial progress in designing titanium-based dental implants and aseptic techniques, infection remains as the most common complication after implantation surgeries. Although, having a weakened immune system or systematic diseases is not seen as contraindicated for dental implants anymore, controlling the immune system is required to avoid surgical site infections after implantation. These patients have to control the surgical site infections by taking a high daily dose of oral antibiotics after dental implantation. The antibiotics oral administration has many side effects such as gastrointestinal symptoms, skin rashes and thrush. Coating antibiotics on the biomaterials surface could be a promising solution to reduce these disadvantages through locally releasing antibiotics in a controlled manner. The aim of this study was to investigate the effects of doxycycline coating layer on titanium-zirconium alloy surfaces in vitro and in vivo. In our previous studies, we demonstrated the chemical presence of doxycycline layer in vitro. In this study, we examined its physical presence using field emission scanning electron microscope and confocal microscope. We also analyzed its controlled released manner using Nano-Drop UV Vis spectrometer. After in vitro characterization of the coating layer, we evaluated its effects on the implant osseointegration in dogs and rabbits. The histological and histomorphometrical results exhibited no significant difference between doxycycline coated and uncoated groups regarding the implants osseointegration and biocompatibility for dental applications. Therefore, coating a doxycycline layer on TiZr implants could be favorable for reducing or removing the antibiotics oral administration after the implantation surgery.

Emerging Biomedical Applications of Algal Polysaccharides.

BACKGROUND: Over the past two decades, there have been substantial progress and a growing body of research on using natural polymeric biomaterials in emerging biomedical applications. Among different natural biopolymers, polysaccharides have gained considerable attraction among biomedical scientists and surgeons due to their biocompatibility, biodegradability, anti-inflammatory, and antimicrobial properties. In recent years, algalbased polysaccharides including agar, alginate, and carrageenan, have been broadly suggested for different biomedical applications. METHODS: The aim of this paper is discussing various possible applications of algal-based polysaccharides in biomedical engineering particularly in controlled drug delivery systems. The main properties of each algal polysaccharide will be discussed, and particular drug delivery applications will be presented. RESULTS: Algal polysaccharides can be detected in a group of photosynthetic unite as their key biomass constituents. They provide a range of variety in their size, shape, liquefaction, chemical stability, and crosslinking ability. In addition, algal polysaccharides have shown exceptional gelling properties including stimuli-responsive behavior, softness, and swelling properties. CONCLUSION: All the mentioned properties of alga polysaccharides lead to their successful usage in biomedical applications specially targeted and controlled drug delivery systems such as particles, capsules, and gels.