Romanian Journal of Medical and Dental Education Vol. 8, No. 10, October 2019 TYPES OF BARRIER-MEMBRANE IN PERIODONTAL THERAPY OF GUIDED TISSUE REGENERATION Diana Anton1, Irina-Georgeta Sufaru2*, Maria-Alexandra Martu2*, Georgeta Laza Demirbuken1, Raluca Mocanu1, Silvia Martu2 1Phd Student ”Grigore T. Popa” University of Medicine and Pharmacy, Iaşi, Romania, 2”Grigore T. Popa” University of Medicine and Pharmacy, Faculty of Dental Medecine, 16 Universitatii Str., 700115, Iasi, Romania. Coressponding author: Sufaru Irina Georgeta: [email protected] Martu Maria-Alexandra: [email protected] Abstract The present resorbable and non-absorbable membranes act as a physical barrier to prevent the fall of the connective and epithelial tissue in defect, favouring the regeneration of periodontal tissues. These conventional membranes have many structural, mechanical and biofunctional limitations. It is clear that the "ideal" membrane for use in periodontal regenerative therapy has not yet been developed. Based on a biomaterial-based approach, it was assumed that a biologically designed and functionally sized nanofibre material closely mimicking native ECM could succeed as the next generation of GTR / GBR membranes for periodontal tissue engineering. Keywords: guided tissue regeneration, barrier-membrane, periodontal surgery The strategy of isolating a high-density polytetrafluoroethylene, periodontal defect with a material PTFE (for example, Cytoplast® TXT-200, (resorbable or non-resorbable) which will Osteogenics Biomedical, Lubbock, TX, function as a physical barrier to prevent US) and (2) high density gingival cell invasion led to the creation of polytetrafluoroethylene reinforced with GTR / GBR membranes [1]. These titanium (for example, Cytoplast® Ti-250, membranes must have: (1) Osteogenics Biomedical, Lubbock, TX, biocompatibility to allow integration with USA). host tissues without giving inflammatory PTFE membranes are inert and responses, (2) adequate resorption profile biocompatible, act as a cellular barrier, to match the new tissue formation, (3) provide space for tissue regeneration and appropriate mechanical and physical allow tissue integration. It has been properties to allow for in vivo placement suggested that there is a favourable and sufficient resistance to be able to help correlation between the level of bone prevent membrane collapse and to fulfil regeneration and the protection of space the barrier function [2]. [3]. Studies have shown that titanium The RTG / ROG membranes are reinforcement of high density PTFE divided into two groups, non-resorbable membranes results in a higher regenerative and resorbable, depending on their capacity compared to traditional extended degradation characteristics. PTFE membranes, mainly due to the additional mechanical support provided by Stability / degradation characteristics of the titanium frame to the compression GTR / GBR membranes forces exerted by the superimposed soft The so-called non-resorbable tissue. One of the disadvantages of non- membranes (Table 1) for the RTG / ROG resorbable membranes is the need for procedures currently on the market are (1) additional surgery to remove them, which 6 Romanian Journal of Medical and Dental Education Vol. 8, No. 10, October 2019 involves not only additional pain and leached, usually an inorganic salt (for discomfort, but also an economic burden. example, sodium chloride or organic To eliminate the second surgical sugars) of the desired particle size, is procedure, resorbable barrier membranes combined with a polymer solution in a have been developed [4]. Processing matrix. After evaporation of the solvent, techniques based on either melting (ie, the salt or sugar crystals are dissolved in polymer heated above melting temperature water, which leaves a porous polymeric or melting temperature of glass) or solvent structure [6]. In this technique, the pore casting were used to manufacture polymer size and the porosity level of the based membranes for GTR / GBR membrane / scaffold can be adjusted by applications. Solvent formation / particle adjusting the particle size and salt or sugar leaching and phase inversion [5] are / polymer ratio respectively. common methods of fabricating porous, Unfortunately, the organic solvents three-dimensional, and / or membranous commonly used in this technique can schemes for tissue engineering. In the adversely affect the response of cells and solvent / particulate-lyophilization tissue after implantation. molding method, a porogen which can be Table 1. List of available membranes Resorption Commercial Composition Mechanical Degradation Biologic degree name resistance rate property Non- Cytoplast High-density N/A Non- Biocompatible resorbable TXT-200 polytetrafluoroethylene degradable (d-PTFE) Cytoplast PTFE reinforced with N/A Non- Biocompatible Ti-250 titanium degradable Synthetic Resolut LT Poly-DL-lactic-co- 11.7 MpA 5-6 months Biocompatible resorbable gliyolic Vicryl Polyglactin 910 N/A 9 months Biocompatible Collagen- Atrisorb Lactid poly-DL and N/A 6-12 months Biocompatible based solvent resorbable AlloDerm Collagen type I from 9.4-21.5 16 weeks Biocompatible human cadaver MPa Bio-Gide Collagen type I from 7.75MPa 24 weeks Biocompatible pig tegument BioMend Collagen type I from 3.5- 18 weeks Biocompatible Extend bovine tendon 22.5MPa Cytoplast Collagen type I from N/A 26-38 weeks Biocompatible RTM bovine tendon Most synthetic polymer resorbable Their resorption rate is important because membranes for periodontal regeneration these membranes must function for at least on the market are based on either 4-6 weeks to allow successful regeneration polyesters (for example, poly (glycolic) of the periodontal system. In general, acid (PGA), poly (lactic acid) (PLA), poly biodegradation of these polyesters (caprolactone) and their copolymers or involves the non-enzymatic cleavage of collagen derived from tissue [7]. PGA and PLA into the bypassed acids and, Polyester-based membranes (Table 1) are respectively, lactic acids, which are biocompatible, biodegradable, and common end products of digestion. clinically manageable compared to PTFE carbohydrates. membranes and allow tissue integration. 7 Romanian Journal of Medical and Dental Education Vol. 8, No. 10, October 2019 Milella et al. [8] evaluated the response limits their use in GTR / GBR morphological and mechanical applications. characteristics of polyester based Collagen is a major component of membranes available on the market (for the natural extracellular matrix (ECM). example, Resolut® LT and Biofix®). Collagen-based membranes derived from Although the membranes initially showed tissues of human skin (Alloderm®, high resistance (~ 12-14 MPa), they LifeCell, Branchburg, NJ, USA), bovine completely lost their structural and tendon (Cytoplast® RTM Collagen, City, mechanical properties within 4 weeks of State, USA) or porcine skin (Bio-, incubation in culture medium. The Osteohealth, Shirley, NY, USA) are maximum resistance after 14 days of important alternatives for synthetic exposure decreased significantly (below 1 polymers in GTR / GBR procedures due to MPa). In a study by Li et al. [9], their excellent cell affinity and performed on nano-hydroxyapatite / biocompatibility [10]. However, type I polyamide-66-processed membranes with collagen may have limitations in its use, a porosity gradient, it was suggested that due to the high cost and poor definition of the addition of n-HAp guarantees a its commercial sources, which makes it membrane with good tensile strength (2-3 difficult to control the degradation and MPa). In addition, the reported cellular mechanical properties. Fig. 1 - (A) AlloDerm® (AD) Macrophotography. AD is a minimally treated, non-cross-linked, freeze- dried dermal matrix collagen-based graft. (B) The SEM image shows the fibrous nature and morphology of the highly porous graft. (C and D) SEM images of the Cytoplast® RTM membrane. (C) general structure of collagen membrane and (D) 3D microstructure of bovine tendon collagen, composed of micro and nano collagen fibres. AlloDerm® is a lyophilized The biomechanical properties and acellular dermal matrix graft (Figure 1) stability of the collagen matrix can be composed mainly of type I collagen improved by physical / chemical cross- derived from human cadaveric skin. linking, ultraviolet (UV), genipine (Gp), According to its manufacturer, this process glutaraldehyde, 1-ethyl-3- itself does not cause the destruction of the (3dimethylaminopropyl) carbodimide biochemical structural cues necessary to (EDC) hydrochloride. Exogenous cross- maintain tissue regenerative properties and linking agents, such as Gp, have been leaves behind an extracellular collagen reported to not only significantly enhance matrix that provides the basis for tissue the stability of collagen-based tissues, but structure and guides cellular functions also reduce its antigenicity. The formation [11]. of additional inter- or intramolecular crosslinks in collagen fibres enhances the 8 Romanian Journal of Medical and Dental Education Vol. 8, No. 10, October 2019 mechanical properties of biological tissues using film casting, dynamic filtration and [12]. Bottino et al. [7] investigated the synthetic e-spinning (eg PCL) and addition of a natural cross-linking agent, collagen, chitosan [9]. The membranes genipin (Gp), to the AlloDerm® were prepared with or without therapeutic rehydration protocol, demonstrating that it drugs, growth factors and / or calcium affects the mechanical properties and