Pellegen® is a bioactive inorganic chemical in the class of silicon substituted phosphates (SSPs). Aiding in the the regeneration of in vivo tissue that it is in contact with, it is biologically inductive. Acting by modulating multiple cellular growth and differentiation factors, it also has been shown to affect gene expression. Because of its mechanism of action at the cellular biochemical level, it must be administered or applied in the fluid surrounding cells making its ionic content available for cellular regulation. Whether on oral mucosa, broken skin, i.e. ulcers, etc., or placed surgically, the various formulations of this class can assist the repair of the range of musculoskeletal tissue types. The composition of Pellegen® has been shown over a long history to have a significant effect on tissue regeneration across the widest range of tissue types.

In the early 1970s, the successful use of SSPs of the composition of Pellegen® was demonstrated clinically. Used in orthopaedics, it statistically reduces the incidence of non-union fractures in trauma. Additionally, the inherent antimicrobial activity of SSPs makes them particularly useful in orthopaedics. Also, in other bone applications, it is clinically used as filling material in benign tumor surgery, for reconstruction of defects in facial bones, for treatment of periodontal bone defects, in repairing orbital “blowout” fractures, in spinal fusion, and for reconstruction of the iliac crest defect after bone graft harvesting, among a few of the FDA approved applications.

Perhaps, the widest successful use of SSPs has been in dental medicine. Here, the ability of SSPs to successfully reconstitute bone / tissue interfaces was proven in periodontal disease adding to all the other bone uses. This soft tissue to bone connectivity was further confirmed by the ENT use in tympano-ossicle reconstruction. Anchoring dental implants in the high-load, contaminated, alveolar ridge has led researchers to prosthetic fixation success in orthopaedics preventing loosening.

With many other FDA approved dental applications exposing SSPs to oral ingestion, the safety profile of SSPs is confirmed without exception since first being used in the 1970s. Now manufactured by the ton for FDA approved dental medicine, safety without allergenic response is magnified by the voluminous exposure over the extended time. There have been no adverse events reported due to the chemical composition of SSPs.

In tissue engineering, some of the most challenging problems include delivery of cellular mediators of growth and differentiation factors to sites for repair and regeneration, controlled release of factors, persistence of factor activity at the site of delivery allowing continuation of healing, and perhaps most limiting is cost. Most in-vivo normal mechanisms of cellular repair and maintenance depend on a time dependent, quantitative, and qualitative sequence supplying a constant delivery of thousands of interrelated factors produced by a renewable responsive complex of intracellular chemical pathways. The half-life of many of the multitudes of these chemicals is often measured in seconds. For example, the half-life of rhBMP is ~20-30 seconds. With a cost of thousands of dollars, kick starting one segment of a complex metabolic pathway is, to say the least, very risky.

SSPs address many of these problems and limitations. They are easily placed directly on tissues such as open skin or the oral mucosa or applied in surgical procedures, mixed with carriers, or incorporated in or on devices, etc. Adding SSPs to resorbable fixation plates and screws, etc. with various compositions such as polylactic /polyglycolic acid formulations imparts benefits to the devices such as preventing granulation and increasing rate of substitution by normal healed tissue. Used as in dental implants, they fix the prosthesis to bone. All of these attributes are made possible by a persistence of the SSP where placed without it interfering with normal metabolism. Controlled release is made possible by forming the glass matrix at 1350℃. Elution of the ionic dissolution products (e.g. calcium, phosphorus, silicon, and sodium) in the SiO2-CaO-Na2O-P2O5 system continues for months culminating in complete absorption. This material when used to implant a total joint costs less than $100 while preventing all the consequences and complications associated with particulate loosening.

Treatment / Application

Ease of use is a hallmark of SSPs. For diabetic ulcers, the wound must be debrided using the roughness of a gauze 4 X 4 pad, and cleansed with an aqueous, water miscible solution such as hydrogen peroxide. Pellegen® is applied in a single granular layer and covered with a gauze pad[s]. As long as the wound remains free of necrotic material, fibrin, etc., and there is Pellegen® visible, it is not necessary to either add more Pellegen® or redebride the wound. It is difficult to use either too much or too little Pellegen®. Preferably, there is a single layer of the granular matrix, and not an excess retaining tissue fluid. Too much material, also, does not allow the wound to “breathe”.

Infection in the surrounding tissue should be appropriately topically, orally, parenterally treated with the lowest generation antibiotic to which the cultured pathogen is susceptible. As SSPs are inherently antimicrobial, it is not necessary to use any antibiotic directly on the wound. Water miscible products such as 1-2% acetic acid on burns to prevent Pseudomonas may be used in place of peroxide or normal saline, etc.

Adverse reactions / Complications

In the decades of use of SSPs, there have been no adverse reactions to the chemical composition of Pellegen®. Like sand, there is potential for mechanical irritation, which is simply treated by removal from the site. SSPs are non-allergenic. Particles may be inhaled, but are cleared by coughing, and are ultimately completely absorbed.

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