Apoptosis

RE V IE W

Apoptosis: an introduction for the endodontist

P. G. Satchell1, J. L. Gutmann2 & D. E. Witherspoon3
1 Private Practice Limited to Endodontics, Houston, 2Private Practice Limited to Endodontics, Dallas, and 3Private Practice Limited to Endodontics, Plano,Texas, USA

Abstract
Satchell PG, Gutmann JL, Witherspoon DE. Apoptosis:
an introduction for the endodontist. InternationalEndodontic Journal, 36, 237^245, 2003.

Apoptosis plays an important role in many aspects of endodontics, yet there is a paucity of information in this regard in the endodontic literature. Apoptosis is a single deletion of scattered cells by fragmentation into membrane-bound particles that are phagocytosed by other cells. It is a key process inthe embryological development of the tooth,periodontal ligament and supporting oral tissue in the progression of oral disease, bone resorption,

immunological response and in£ammation, and in wound healing and certain pharmacological e¡ects. The understanding of the ability of clinical materials to induce or inhibit apoptosis and the investigation of apoptosis as it relates to the pathogenesis of pulpal and periradicular pathology may eventuallylead to new treatment approaches for the endodontist. The purpose of this review is to familiarize the clinical endodontist with current knowledge on apoptosis as it relates to the pulp and periradicular tissues. Keywords: apoptosis.
Received 21May 2001; accepted 2 January 2003

Introduction
Apoptosis is essentiallycell suicide,andwas¢rstdescribed in the British Journal of Cancer in 1972(Kerr et al. 1972). According to these authors, at the appropriate time and under certain conditions, cells self-destruct without damaging adjacent cells. This process is occurring constantly and can happen to seemingly healthy cells. Whilst it is unique to animals and is studied classically in the nematode worm Caenorhabditis elegans, it has been increasingly studied in vitro and in higher organisms.There has been an explosion in the number of articles on the subject of apoptosis. A conservative estimate places the number at nearly 45 000. Whilst apoptosis has been a topic of extensive research in the scienti¢c community for some time, it has received little attention in the endodontic literature. The purpose of this article is to familiarise the endodontist with apoptosis and to discusssome of the potential implications of apoptosis to endodontics.

Why and how is apoptosis important to endodontics? Apoptosis plays a ubiquitous role in the body. Amongst other things, apoptosis is a key process in oral development (Vaahtokari et al. 1996, Harada et al. 1998, Cerri et al. 2000), the progression of oral disease (Polverini & Nor 1999), periradicular lesion development (Onishi et al.1997), resorption (Hughes & Boyce 1997), immunological response and in£ammation (Onishi et al. 1997), wound healing (Fanning et al.1999) and in certain pharmacological e¡ects (Hughes et al.1995). The understanding of the ability of clinical materials to selectively induce or inhibit apoptosis is leading to new treatment modalities (Bamford et al. 2000). An understanding of the mechanisms ofapoptosis may lead to adjunctive treatments for pulpal and periradicular diseases through yet unexplored pathways. What is the apoptotic process? The entire process of apoptosis takes about 1 h from initiation (Figs 1and 2). The initiating triggers are many and varied, and are grouped broadly as physiological or nonphysiological. These include, but are not limited to,

Correspondence: Dr James L.Gutmann, 1416 Spenwick Terrace, Dallas, Texas,TX 75204-5529, USA (Tel.: þ1 214 827 5378; fax: þ1 214 827 4848; e-mail: jlgutmann@earthlink.net).

ß 2003 Blackwell Publishing Ltd

International Endodontic Journal, 36, 237^245, 2003

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Apoptosis Satchell et al.

Figure 1 The major stages of apoptosis include the initiating trigger (1) that leads to the activation of the intracellular...