Abstract
Marginal periodontal healing following both invasive and non-invasive therapies is influenced by a large number of systemic and local factors. In order to optimize healing, a lot of effort is put into minimizing possible sources of infection both in performing different periodontal therapies as well as during the healing period. Mechanical root surface debridement inevitably produces an infected smear layer which covers the exposed mineralized root surface. The overall aim of the studies on which the present thesis is based, was to characterize how the nature of the root surface may modify the quality of periodontal healing tissues.
The general working hypothesis was that a smear-free dentin surface in which collagen has been exposed provides a more biocompatible surface for periodontal healing compared to a mineralized and smear covered root surface. This thesis is based on experimental in vitro (I-V,X), in vivo (II,VI-VIII) and in situ (IX,X) studies. Pre-clinical confirmation of the efficacy of EDTA in removing both smear and exposing collagen on a root surface was obtained before the beneficial effect of the procedure was established in vivo as well as its clinical utility. Similarly, previously recommended etching procedures were studied and their low pH appeared to impair healing as seen both in the initial cellular event in colonization of denuded root surfaces (II) and in a necrotizing effect on healthy periodontal tissue in the vicinity of an experimental periodontal wound (VI). Marginal periodontal healing after several weeks appeared also to suffer from etching at low pH while etching at neutral pH appeared not to interfere with spontaneous healing (VII,VTII). The results from the in situ studies indicate that the different root surface debridement and etching procedures functioned along the same principles as observed in vitro with some modifications probably due to influence from the surrounding tissues, blood and the nature of the periodontitis affected root surfaces (IX,X).
Two principally different areas of clinical use for EDTA etching are evident: Firstly, in conventional non-surgical and surgical periodontal therapy to remove smear in order to minimize post-surgical infection. Secondly, in regenerative procedures to expose an intact collagenous matrix which may provide for retention of implants of biologically active substances such as growth factors in addition to serving as a biocompatible surface for periodontal ligament cell colonization.
