www.swissbiomat.ch
A Personal Website on Biomaterials and Related Sciences

Sections
Home
Editorial
Main Article
Questions to...
A Company Profile
"Pearl of the Web"
Glossary
Resources
Index of Issues


Main Article
Collection of links
Company Profile
Degradable Solutions AG
"Pearl of the Web"
Biomat.net

The Glossary

Issue 101

Angiogenic - which promotes or develops blood vessels; which promotes an increase in vascularization (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Biodegradable Polymer - a polymer that breaks down when placed in a biologic environment (adapted from http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Bone Substitute - Synthetic or natural materials for the replacement of bones or bone tissue. They include hard tissue replacement polymers , natural coral, hydroxyapatite, beta-tricalcium phosphate, and various other biomaterials. The bone substitutes as inert materials can be incorporated into surrounding tissue or gradually replaced by original tissue (http://medical.webends.com/kw/Bone+Substitutes)

CAD / CAM - The utilization of computer technology in the design, management, control, and operations of the manufacturing facility through either direct or indirect computer interface with the physical and human resources of the company or organization. True CAD/CAM systems strive to integrate both the design and manufacture processes into a workable whole through shared databases in computer memory (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Chemotactic - Chemotactic factor: A compound that produces positive directed migration of one or more kinds of leukocytes. The cells follow a chemical gradient. Chemotactic factors are of three general sources: bacterial (N-formylated peptides, which are unique to the initiation of bacterial protein), plasma proteins (e.g., C5a , one of the activated products of either the classical or alternative pathways of complement activation ), and cells (e.g., the cytokine , TGF-beta). (http://www.kumc.edu/instruction/medicine/pathology/ed/keywords/kw_chemotac.html)

Comb Polymer - A polymer composed of comb macromolecules. Comb macromolecules: A macromolecule comprising a main chain with multiple trifunctional branch points from each of which a linear side-chain emanates. Notes: 1. If the subchains between the branch points of the main chain and the terminal subchains of the main chain are identical with respect to constitution and degree of polymerization, and the side chains are identical with respect to constitution and degree of polymerization, the macromolecule is termed a regular comb macromolecule .2. If at least some of the branch points are of functionality greater than three, the macromolecule may be termed a brush macromolecule . (http://www.iupac.org/reports/1996/6812jenkins/substances.html)

Dental amalgam - Amalgam is the most common material used for fillings. Also known as silver filling it is a mixture of mercury and an alloy of silver, tin and copper. Mercury makes up about 45-50 percent of the compound and is used to bind the metals together and to provide a strong, hard, durable filling. After years of research, mercury has been found to be the only element that will bind these metals together in such a way that can be easily manipulated into a tooth cavity (http://www.dentalfind.com/glossary).

Dental implant - A dental implant is an artificial tooth root surgically placed directly into the jawbone where a tooth is missing. Once the implant has healed, a bridge, or replacement tooth, will be attached to the artificial root. Implants provide a good alternative to crowns and bridges due to the fact they are in no way attached to neighboring teeth and thus look and feel like natural teeth.
Dental implants are generally made of titanium, a surgical metal that bonds well to bone. The cylindrical implant is designed to integrate into the structure of your jawbone, forming an anchor for your replacement tooth. Implanting the artificial root requires surgery, usually under a local anesthetic. During surgery, an incision is made in the gum to expose the jawbone, the bone is prepared, and the implant is inserted into the prepared site. Usually this area is left undisturbed for 4-6 months to ensure proper healing. Once the site has healed, a second procedure is required to clear the gum away from the implant and fasten a post, which will attach to the replacement tooth. (http://www.dentalfind.com/glossary/dental_implant.html)

Extra cellular matrix - An intricate network of macromolecules occupying the spaces between the cells of multicellular animals. It is particularly important in the reinforcement of support tissues. Under the light microscope, it appears as a structureless mass of ground substance with embedded connective tissue fibers. The ground substance consists primarily of proteoglycans and glycoproteins, whereas the fibers consist mainly of fibrous proteins such as collagen. Depending on the relative quantities and type of its constituent macromolecules, the e.m. can display a number of forms, ranging from the calcified hard structures of bone and teeth to the transparent matrix of the cornea (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Fixed prosthodontics - The three main types of prosthesis are removable dentures , tooth supported fixed bridge , and dental implant supported bridge . Removable dentures are the least expensive of the three options and initially are esthetically pleasing. Due to physical health and/or economic conditions, removable dentures are the only options available for patients. However, in most cases they are simply a good interim solution for patients undergoing osseointegration (dental implant treatment.) Of the other main types of prosthesis, tooth supported fixed bridges are a better option than removable dentures. The main benefit is that they are removable only by a dental specialist and not by the patient. They are also generally more esthetically pleasing than removable dentures and also offer better chewing ability. The best option for prosthesis is the dental implant support bridge. Dental implants provide a solid anchor for teeth and actually stimulate bone growth. Additionally, adjacent teeth are not impacted. They are also the most esthetically pleasing. However, dental implants are the most initially expensive of the three main options of prosthesis. They also require the presence of adequate bone in order for it to be placed. If adequate bone is absent, a bone graft procedure may be required (http://www.dentalfind.com/glossary).

Growth factors - organic compounds other than those required as carbon and energy sources which are needed by many organisms for proper growth and development, and which may include vitamins, amino acids, purines, etc.; a general term for specific peptides or proteins that are released by certain cells and bind to specific cell membrane receptor sites to influence cells to divide or remain quiescent (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Guided Bone Regeneration (GBR) - Guided Bone Regeneration (GBR) refers to procedures that attempt to regenerate bone prior to the placement of bridges or, more commonly, implants . This is accomplished using bone grafts and biocompatible membranes that keep out tissue and allow the bone to grow. (http://www.advancedperiodontics.com/bone_regeneration.htm)

Guided Tissue Regeneration (GTR) - Guided Tissue Regeneration (GTR) is a procedure that enables bone and tissue to re-grow around an endangered tooth or if the tooth is lost, to increase the amount of bone for implant placement (http://www.dentalfind.com/glossary)

Hedgehog - Hedgehogs (Hhs) are intercellular signaling molecules that regulate tissue patterning in mammalian development. Mammalian Hhs include Sonic hedgehog (Shh), Indian hedgehog (Ihh), and Desert hedgehog (Dhh). (...) ( Hedgehog Signaling Regulation of Insulin Production By Pancreatic [Beta]-Cells, Habener, Joel F., Diabetes; 12/1/2000) (http://www.medbioworld.com/ then using Hi-Beam Research with "hedgehog")

Homeobox - The homeodomain is a DNA-binding domain, and many homeobox genes have now been shown to bind to DNA and regulate the transcription of other genes. Thus homeodomain proteins are basically transcription factors, most of which play a role in development.
An overview of homeobox genes can be found in:Guidebook to the Homeobox Genes . 1994. Denis Duboule (ed.) Oxford University Press, Oxford. ISBN 0-19-859939-0 (hardcover), 0-19-859940-4 (paperback). (http://www.biosci.ki.se/groups/tbu/homeo.html "The Homeobox Page")
Denis Duboule is professor at the University of Geneva, Switzerland.
Homeobox gene - A gene containing a 180-base-pair segment (the “homeobox”) that encodes a protein domain involved in binding to (and thus regulating the expression of) DNA . This homeobox is remarkably similar in many genes with different functions. (http://www.iscid.org/encyclopedia/Homeobox_Gene)
Homeobox - A homeobox is a stretch of DNA sequence found in genes involved in the regulation of the development ( morphogenesis ) of animals , fungi and plants. Genes that have a homeobox are called homeobox genes and form the homeobox gene family . (...) (http://en.wikipedia.org/wiki/Homeobox)

Ink Jet Technology - Inkjet printing, like laser printing, is a non-impact method. Ink is emitted from nozzles as they pass over a variety of possible media, and the operation of an inkjet printer is easy to visualise: liquid ink in various colours being squirted at the paper to build up an image . A print head scans the page in horizontal strips, using a motor assembly to move it from left to right and back, as another motor assembly rolls the paper in vertical steps. A strip of the image is printed, then the paper moves on, ready for the next strip. To speed things up, the print head doesn't print just a single row of pixels in each pass, but a vertical row of pixels at a time. There are several types of inkjet technology but the most common is "drop on demand " (DOD). This works by squirting small droplets of ink onto paper, through tiny nozzles: like turning a hosepipe on and off 5,000 times a second. The amount of ink propelled onto the page is determined by the driver software that dictates which nozzles shoot droplets, and when . (...) (http://www.pctechguide.com/13inkjets.htm)

Maxillofacial Surgery - maxillofacial surgery treats conditions, defects, injuries, and esthetic aspects of the mouth, teeth, jaws, and face and performs a wide range of surgical procedures on the bones and soft tissues of the face, mouth and neck. It includes a wide range of procedures:
- Cosmetic surgery--birth defects, trauma, injury, disease or age can upset the appearance of the face. Cosmetic maxillofacial surgery can restore features to a more aesthetically pleasing form.
- Orthognathic surgery (correcting misaligned jaws)--misaligned jaws can create problems with chewing and swallowing, as well as psychological concerns over aesthetic appearance.
- Cancer surgery of the face and neck--maxillofacial surgeons can monitor, diagnose and treat potentially cancerous lesions in these areas.
- Dental implant surgery--the loss of even one tooth can affect chewing and digesting, and pose the risk of jawbone resorption (loss). Maxillofacial surgeons can create and apply dental implants, artificial tooth roots, to sit in the place of the lost tooth. Artificial crowns can sit upon these implants and function just as a natural tooth would.
- Monitoring Facial Pain--often, facial pain comes from the temporomandibular joint (TMJ), the joint that opens and closes the mouth.
- Treating facial trauma-- treating broken facial bones, stictch deep cuts or wounds, and using wires and splints to hold injured bones or muscles together (http://www.dentalfind.com/glossary).

Membrane - In Guided Bone Regeneration, a membrane is a barrier placed over a periodontal defect to prevent the in-growth of cells from the gingival connective tissue, epithelium and the periodontal ligament. GBR membrane materials must maintain their barrier function long enough to allow osteoblasts to migrate into the wound. Resorbable and non-resorbable membranes have been used as a GBR barrier (http://www.thejcdp.com/issue018/aslan/02aslan.htm).
Membranes have four purposes in bone regeneration:
1. space creating
2. protection of blood clot and granulation tissue
3. exclusion of competing non-osteogenic cells
4. local accumulation of growth factors and bone promoting substances. (http://www.spallek.com/periodont/peris23.html)

Mitogen - (or mitogenic) An agent that stimulates DNA production and cell division (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Omentum - A sheet of fat that is covered by peritoneum. The greater omentum is attached to the bottom edge of the stomach, and hangs down in front of the intestines. Its other edge is attached to the transverse colon. The lesser omentum is attached to the top edge of the stomach, and extends to the undersurface of the liver (http://www.medterms.com/script/main/art.asp?articlekey=4632 )

Orthodontics - Orthodontics is the branch of dentistry devoted to correcting tooth alignment and bite problems. Orthodontists, dentists trained in orthodontics, straighten teeth and correct over or underbites. A perfect smile should consist of straight teeth, be gap and overlap-free, and align top teeth with the bottom. Mouth injuries, prolonged pacifier use in infancy, thumb-sucking in early childhood, and supernumary or impacted teeth can all cause misalignment. In some cases, a gap left by a knocked-out tooth creates a space for other teeth to shift into. Most often, though, orthodontic problems occur simply because the teeth and mouth are growing at different speeds (http://www.dentalfind.com/glossary)

Osseoconduction - a physical effect by which the matrix of the graft forms a scaffold on which cells in the recipient are able to form new bone (http://www.lifesteps.com/gm/Atoz/ency/bone_grafting_pr.jsp)

Osseoinduction - a chemical process in which molecules contained within the graft (bone morphogenetic proteins) convert the patient's cells into cells that are capable of forming bone (http://www.lifesteps.com/gm/Atoz/ency/bone_grafting_pr.jsp)

PDGF = Platelet derived growth factor - glycoprotein growth factor that stimulates cell proliferation and chemotaxis in cartilage, bone, and many other cell types after being produced by mesenchymal cells or released by platelets during clotting (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

PRF = Platelet Rich Fibrin - preparations in which blood is drawn from the patient and then centrifuged at high speeds to create platelet-rich plasma. The platelet-rich plasma is activated with various reagents to convert fibrinogen to fibrin, creating a gel like substance, which in turn is applied immediately to the wound (http://www.healthlink.com/provider/medpolicy/policies/pharmacology/platelet_growth_factors.html)

Rapid prototyping - Rapid prototyping is the name given to a host of related technologies that are used to fabricate physical objects directly from CAD data sources. These methods are unique in that they add and bond materials in layers to form objects. Such systems are also known by the general names solid freeform fabrication and layered manufacturing and offer advantages in many applications compared to classical subtractive fabrication methods such as milling or turning:
- Objects can be formed with any geometric complexity or intricacy without the need for elaborate machine setup or final assembly;
- Objects can be made from multiple materials, or as composites, or materials can even be varied in a controlled fashion at any location in an object;
- Solid freeform fabrication systems reduce the construction of complex objects to a manageable, straightforward, and relatively fast process.
(http://home.att.net/~castleisland/home.htm The Worldwide Guide to Rapid Prototyping )

Scaffold - A three-dimensional biocompatible construct (may be seeded with cells) that serves as a temporary implantable tissue; generally fated to biodegrade and be replaced by natural tissue (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Signal molecules - the biological molecules responsibles for signal transduction.
Signal transduction - In biology , signal transduction is any process by which a cell converts one kind of signal or stimulus into another. Processes referred to as signal transduction often involve a sequence of biochemical reactions inside the cell, which are carried out by enzymes and linked through second messengers . Such processes take place in as little time as a millisecond or as long as a few seconds. Slower processes are rarely referred to as signal transduction.
In many transduction processes, an increasing number of enzymes and other molecules become engaged in the events that proceed from the initial stimulus. In such cases the chain of steps is referred to as a " cascade " and the result is that a small stimulus elicits a large response
(... see very complete description of Signal transduction in: http://en.wikipedia.org/wiki/Signal_transduction)

Stem Cells - Undifferentiated cell in embryo or adult which can undergo unlimited division and give rise to one or several different cell types. In adults, an undifferentiated cell from which some renewable tissues (blood, skin, etc.) are formed (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Stereophotolithography - one of the methods of rapid prototyping, which achieves construction of 3D objects using monomers or particles, bound together by chemical or physical processes conducted through driving softwares developed from computer aided designs. See Rapid prototyping.

Telemanufacturing - Telemanufacturing permits centralized manufacturing with decentralized design teams. Telemanufacturing through the Internet allows designers to create a part model, transfer it to a manufacturing facility, and there produce a physical model through rapid prototyping (RP) techniques. Information security should be inherent to file transfers. In this project, we focus on incorporating the Internet in RP production and on the manufacturability and dimensional stability of physical RP parts. We have found eperimentally that components produced by fused deposition have dimensions that compared favorably with design specifications, except when corrupted by the security and file transfer processes. (http://prism.asu.edu/research_projectarchives.asp)

TGF a and b = Transforming growth factors - Transforming growth factor alpha (TGF alpha) is a small 50 amino acid residue long mitogenic protein that contains three disulfide bridges. TGF alphas are secreted by human cancer cells and retrovirus-transformed fibroblasts. TGF alpha acts alongside other growth factors such as type-beta transforming growth factor (TGF beta) to activate phenotypic cellular changes in certain cell lines.
(http://www-nmr.cabm.rutgers.edu/photogallery/structures/html/page4.html)
TGF-beta exists in at least five isoforms, known as TGF-beta-1 , TGF-beta-2 , TGF-beta-3 , TGF-beta-4 , TGF-beta-5 , that are not related to TGF-alpha. (...) The biological activities of TGF-beta are not species-specific. The various TGF-beta isotypes share many biological activities and their actions on cells are qualitatively similar in most cases although there are a few examples of distinct activities (...) The most pronounced differences in the TGF-beta isoforms is their spatially and temporally distinct expression of both the mRNAs and proteins in developing tissues, regenerating tissues, and in pathologic responses.
(http://www.grt.kyushu-u.ac.jp/spad/account/ligand/tgf-beta.html)

Tissue Engineering - The application of the principles of life sciences and engineering to develop biological substitutes for the restoration or replacement of tissue or organ function (http://www.ptei.org/ Pittsburgh Tissue Engineering Initiative)

Tissue Regeneration - Process which, using signalling molecules, growth factors, scaffolds and/or cells, tries to regenerate in situ damaged or partly destroyed tissues.

WNT - Wnt proteins form a family of highly conserved secreted signaling molecules that regulate cell-to-cell interactions during embryogenesis. Wnt genes and Wnt signaling are also implicated in cancer. As currently understood, Wnt proteins bind to receptors of the Frizzled family on the cell surface. Through several cytoplasmic relay components, the signal is transduced to beta-catenin, which then enters the nucleus and forms a complex with TCF to activate transcription of Wnt target genes. These pages contain some diagrams of the pathway. Wnt signaling has been discussed in several reviews (...) (http://www.stanford.edu/~rnusse/wntwindow.html)

General

How It Works

The Glossary offers a collection of definitions for some unusual words used in the Issue.

Definitions will be completed for each subsequent issue, and arranged by alphabetical order for easier retrieval.

However, the definitions pertaining to the current issue will be displayed first, in a separate section, and also repeated in the general alphabetical collection.