Discussion.
Calcium hydroxide is recommended as the standard intracanal dressing in root-canal treatment (Bystrom et al. 1985, Sjogren et al. 1991). In the present study, calcium hydroxide was used by 69.7% of the respondents, which is considerably more than the 21.1% in the study of Saunders et al. (1999), the 7% in the study of Jenkins et al. (2001) in the UK or the 9% in the USA (Whitten et al.1996). Ina Dutch study (Siers et al. 2001), the percentage of respondents using calcium hydroxide was 86.2%. These differences between countries are likely to be attributed to the different policies in dental training between universities (Qualtrough et al.1999). Although there was no statistically significant difference between the different age groups in this study, a similar trend, namely a decreased use of calcium hydroxide as a function of the period since graduation of the participants (Table 1) was observed as in some of the previous studies (Saunders et al.1999, Jenkins et al.2001).About one-third of the practitioners did not use an interappointment medicament. Studies have shown that it is almost impossible to create a sterile root canal through cleaning and shaping of the root-canal system and that regrowth of bacteria occurs in an empty root canal (Bystrom & Sundqvist1981, Siqueira et al.2002).Therefore, an intracanal dressing is advocated between appointments when a tooth is treated in more than one session.
Caustic and organic root-canal disinfectants were used by 66.8% (Table 2), despite the well-established use of calcium hydroxide. These products contain organic components such as paraformaldehyde, chlorophenol, parachloromonophenol, creosote, arsenicum anhydride, iodoform. It has been argued that most of these products should be prohibited as they are highly toxic, allergenic, mutagenic and carcinogenic and are harmful to patients (Lewis1998). It has been shown that some of these products caused periodontal destruction and delayed healing of periapical tissues (Kopczyk et al. 1986, Yamasaki et al. 1994, Di Felice & Lombardi 1998), as they can escape from the root canal. In this respect, studies have documented their rapid and strong systemic distribution when used during endodontic treatment (Block et al.1983, Fager & Messer 1986).
The sealing of access cavities between appointments is a determining factor in the inhibition of bacterial leakage and hence the prognosis of root-canal treatment (Saunders & Saunders1994). Cavit1 is the product most favoured by Belgian practitioners (48.2%), with glassionomers being used by 31.3% of the respondents. Studies have shown that Cavit1 adequately sealed access cavities of endodontically treated teeth (Beach et al. 1996), although a bacterial study (Barthel et al. 1999) reported that glass-ionomer was superior to Cavit1.
Cold lateral gutta-percha condensation was the filling technique most frequently used (Table 4). Although it is common knowledge that single-cone gutta-percha fillings are not recommended (Beatty1987), it was still used by16.0% of the respondents. The results in Table 5 show that different types of warm gutta-percha filling techniques were used by all ages. This clearly shows the effort made by a number of practitioners to use other filling techniques than those taught during dental graduate training.
This study also provided information on the endodontic decision making of the participants. On one hand, re-treatment of failed root fillings was the standard choice by the majority of the respondents (Table 8). On the other hand, there was a clear trend towards more apicectomies and extractions with the increase of the size of the periapical lesion. The number of apicectomies and extractions even increased when the lesion was associated with root-filled teeth. Studies have shown that the size of the periapical lesion is not a determining factor in healing (Sjogren et al.1990). The presence of a root filling is also no reason for more radical treatments. Re-treatment should always be the first option, although a number of complicating factors require surgery (Walton & Torabinejad1996).

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