Debe utilizar plataformas de acceso seguro, para realizar la limpieza de celdas hidráulicas y sedimentadores.

Many attempts have been made to achieve periodontal regeneration using a variety of natural and synthetic materials and surgical procedures (Froum and Gomez 1993; Garrett 1996).

1.3.4.1 Open flap debridement

The open flap debridement procedure is a surgical procedure in which the gingival flap is raised, the granulation tissue removed and the root surfaces are instrumented (Ramfjord and Nissle 1974). The flap is then replaced to its original position and sutured. Clinical studies have shown that this procedure leads to an arrest of the progression of the periodontal lesion, resulting in some improvements in clinical parameters (Rosling et al. 1976; Froum and Gomez 1993). However, histological studies have demonstrated that the healing response is neither structurally nor functionally identical to a healthy periodontium in certain features. For example, soft tissue adhesion to the root surface frequently occurs with the formation of a long junctional epithelium (Stahl et al. 1982). Nonetheless, the open flap debridement

procedure, also referred to as conventional flap surgery, has been widely used as the basic periodontal surgical therapy and has served as a control in many clinical trials of other procedures (Cortellini etal. 1993a; Cortellini et ai. 1993b; Kiliçefa/. 1997).

1.3.4.2 Root surface treatment

One of the important components of the periodontal healing process is the root surface which becomes exposed to the oral environment as a result of periodontal disease. This surface functions as one of the wound margins, serving as a source for the renewal of structural components and a surface for new cell attachment and fibre development. Selective alterations of the root surface have been carried out so that it does not contain cytotoxic contaminants, provides chemotactic stimulus for connective tissue cells and supports the migration and attachment of the cells involved in healing (Lowenguth and Blieden 1993).

Citric acid-induced demineralisation of the root surface is aimed at exposing collagen fibres present in cementum or dentine in order to form a barrier against epithelial migration and also allow interdigitation of collagen fibres from the healing connective tissues (Froum and Gomez 1993). Early animal studies demonstrated that topical application of citric acid on previously denuded root surfaces improved the rate of connective tissue healing compared to open flap debridement and resulted in the formation of new attachment and new cementum (Ririe et ai. 1980; Poison and Proye 1983). However, in another animal study citric acid provided little additional benefit over root planing (Nyman et al. 1980) and the procedure did not demonstrate significant clinical improvement in humans (Marks and Mehta 1986). Another agent used for the same purpose has been tetracycline MCI, which has produced similar equivocal results (Lowenguth and Blieden 1993).

Terranova and Wikesjo (1987) proposed a possible therapeutic role for ECM proteins. However, topical application of fibronectin onto root surfaces did not result in additional bone fill (Terranova et al. 1987), and the addition of laminin did not improve the response (Smith et al. 1987).

1.3.4.3 Coronally positioned flap

In order to exclude the gingival epithelium from the healing periodontal

wound or to delay the migration of the epithelial cells, mucoperiosteal flaps

were displaced in a more coronal position. Such coronally positioned flaps have been used mainly in conjunction with other approaches, such as citric acid conditioning (Froum and Gomez 1993), and histological studies in animal models have demonstrated effective results in achieving periodontal regeneration (Crigger et al. 1978). However, in humans this procedure has had some technical difficulties as placement of sutures over occlusal surfaces may result in rupture of the sutures with subsequent release of the flaps. Therefore, the interdental sutures were placed to secure the coronally positioned flaps in humans.

1.3.4.4 Grafting

Bone grafts, of natural or synthetic materials, have been widely used to fill the defects in alveolar bone destroyed by periodontal disease. These procedures have been carried out as adjuncts to open flap debridement surgery, to accelerate periodontal regeneration and obtain improvement in clinical parameters (Brunsvold and Mellonig 1993). The 3 types of grafts which are used most frequently are: i) autogenous bone grafts taken from one part of a patient’s body and transferred to another part in the same individual; ii) allografts taken from donors and transferred to a recipient host of the same species; and iii) alloplasts, synthetic and inert materials such as hydroxyapatite (Brunsvold and Mellonig 1993).

Froum et ai. (1975) reported that over 70% of intraosseous defects were filled when the autogenous bone graft was used. This procedure resulted in significant bone fill compared to the open flap debridement procedure (Froum ef al. 1976). Although several reports have supported the success of autogenous bone grafts, the problems concerning the need of a donor site, time and limited amount of donor material has led to the development of allografts. Urist (1965) showed that demineralisation and freeze-drying of cortical bone allograft material enhances its osteogenic potential. Pearson et al. (1981) noted substantial bone fill using decalcified freeze-dried bone compared to surgical debridement. Although bone grafts

were considered to be inductive to the formation of alveolar bone, it has been noted that they act as space-fillers and the procedure results in new connective tissue attachment with long junctional attachment and very limited regeneration (Wikesjo at al. 1992). Thus, more effective and more predictable procedures are required to completely restore form and function of the periodontal ligament, cementum and alveolar bone.