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 »  Home  »  Endodontic Articles 3  »  Radiographic evaluation of the prevalence and technical quality of root canal treatment in a French subpopulation
Radiographic evaluation of the prevalence and technical quality of root canal treatment in a French subpopulation
Discussion - References.

The sample included in this study were adult patients attending the dental service of the Hôtel Dieu for general dental treatment. The recruitment of subjects was the same as those used by others (De Cleen et al. 1993, Buckley & Spångberg 1995, Saunders et al. 1997, Weiger et al. 1997, De Moor et al. 2000). There is no information available for this patient population, which makes it difficult to extrapolate the data obtained into the population of Paris or of France. However, the dental service attracts a patient population from numerous parts of the city and its surroundings, which eliminates the risk of only including patients previously treated by a limited number of practitioners. Some patients sought care because of the expense of prosthetic treatment, which in general is less at the dental service than in the private sector. It should also be noted that there were other patients who sought care because of the reputation of the university dental service.

PAI distribution according to the different categories of teeth and roots. Intra R, intracoronal restoration
Figure 2. PAI distribution according to the different categories of teeth and roots. Intra R, intracoronal restoration; Extra R, extra-coronal restoration; R-F, root-filling.

Our sample consisted of more women (62%) than men (38%), which may constitute a recruitment bias or reflect some sociologic aspects of the French population. However, similar epidemiological studies reported that gender had no effect on the quality of root filling or the presence of periapical lesions.
Our results showed that 19.1% of the teeth had undergone root canal treatment, which is rather higher than found in studies performed on populations of comparable age (Ödesjö et al. 1990, Buckley & Spångberg 1995, Saunders et al. 1997). They resemble more closely those obtained by Imfeld (1991) on a sample of patients older than 65 years. The high percentage of root-filled teeth may reflect a selection bias with regard to the patient population of our dentistry service or to treatment habits of French dentists. Pulp extirpation for prosthetic reasons are, for example, frequent (Weiss et al. 1998). However, this high number of root-filled teeth confers a greater statistical value to the sample with regard to periapical pathologies if one compares it to other studies (De Cleen et al. 1993, Marques et al. 1998). Moreover, it should be noted that in this study, the assessment of periapical status and technical quality was determined not only by teeth but also by root.
A periapical lesion was associated with 24.4% of the root-filled roots. This figure is in the range of those found in previous studies, which vary from 18 to 61% (De Moor et al. 2000). These findings can be compared with those obtained in France by Gérard (1989), who classified 24.5% of the teeth as being pathological. However, his sample included only radiographs sent by practitioners to the CNAM, the government organization which reimburses part of the cost of the crown when the tooth involved does not present any sign of periapical pathology. These radiographs were therefore selected. It was noted that, despite the prosthetic criteria requiring no existing periapical pathology, one-quarter of the teeth had a periapical lesion. In addition, no indication of age was available in that study. Our results are also difficult to compare with the study performed in France by Hess & Mace (1994), since these authors used two series of radiographs: either radiographs which had been submitted to the CNAM with a view toward prosthetic treatment, with the same reservations as previously cited, or orthopantomograms which are less precise for assessing periapical conditions than the periapical radiographs (Muhammed & Manson-Ring 1982) and are more subject to interobserver variations (Rohlin et al. 1991).
The number of roots classified as having periapical lesions is of interest. Ørstavik et al. (1986) established a Periapical Index (PAI) in correlation with the histological work of Brynolf (1979). The PAI scoring system allows standardization of the different categories, and thus comparisons between studies. Its reliability was established by further investigations (Ørstavik 1988). However, in order to differentiate the normal from the pathologic, the authors proposed a cut-off at a score of 2, since PAI > 2 was considered to be indicative of periapical pathology. This choice was selected by some authors but is, from our point of view, debatable. It is not the purpose of this article to reconsider what can radiologically be interpreted as healthy, but a cut-off point of PAI = 1 may be more appropriate. First, a score of 2 corresponds to an image with a localized widening of the ligament and/or associated signs of bone modifications which may be interpreted as either an ongoing healing process, an established state of irritation, or an evolution toward a pathological state. Since peak incidence of healing or emerging chronic apical periodontitis is at 1 year (Ørstavik 1996), the risks of a questionable image developing a more advanced lesion are increased. Secondly, periapical lesions are in general radiographically underestimated, since the cortical bone must have a 30–50% mineral bone loss to be detectable (Bender 1982). Moreover, as the PAI system was established for maxillary anterior incisors, where the cortical bone is thin, the risk of underestimation of lesions with a PAI > 2 is increased. Thirdly, other authors who did not use the PAI scoring system (Petersson et al. 1986, Hess & Mace 1994, Buckley & Spångberg 1995, Saunders et al. 1997,Weiger et al. 1997, De Moor et al. 2000) considered a localized increase of the periodontal space as a sign of apical periodontitis if bone changes were present. Finally, interobserver agreement is greater for teeth considered to be healthy than it is for grading a pathological state (Reit 1987). It is clear that the choice of cut-off is of primary importance because the number of roots classified as pathologic is approximately doubled if one chooses a limit at grade 2 or 3 (Tables 1–6).
This study also poses the problem of absent teeth, some of which may have been extracted for periapical pathological reasons. The most root-treated teeth were mandibular molars, which were also the most frequently missing, excluding third molars. It is reasonable to suppose that some of these teeth were extracted because of periapical pathology, with or without endodontic treatment. Root-filled teeth that were most frequently associated with pathology are, respectively, the single-rooted teeth > premolars > molars. In this study, if the mandibular incisors are excluded because of low numbers, the teeth that were most often associated with periapical pathology were the maxillary lateral incisors. Another interesting result of the present study concerns the quality of root canal treatment. Only 20.8% of the roots fulfilled the criteria for an acceptable root canal filling, i.e. a radiographically dense filling with its end located between 0 and 2 mm from the apex (European Society of Endodontology 1994). These results are worse than those of most of the other published studies, which show an acceptable root canal filling rate in 30–40% of roots (Petersson et al. 1986, Allard & Palmqvist 1986, Eckerbom et al. 1987, Eriksen et al. 1991, Ödesjö et al. 1990, Imfeld 1991, Buckley & Spångberg 1995, Saunders et al. 1997, Weiger et al. 1997, De Moor et al. 2000). These results therefore indicate that the majority of root canal fillings were performed poorly, despite the fact that the technical quality of care is a key factor in the healing or prevention of periapical pathologies (Strindberg 1956, Sjögren et al. 1990, ANDEM 1996). In addition, these observations only take into account the radiographic image of the treatment. It is therefore impossible to take into account the working conditions and especially disinfection of the root canal prior to filling, which is a major factor in terms of the outcome (Sjögren et al. 1997).
On the other hand, the poor technical quality must be balanced by the fact that 73.3% of the teeth with unacceptable root canal fillings did not present with radiographic signs of pathology. These root fillings may have been completed recently with insufficient time having elapsed for lesions to develop. Poorly sealed root-fillings are likely to become reinfected due to leakage, and thus represent a high risk for future periapical inflammation. At the same time, the filling criteria are not the only factors affecting the outcome and many studies have underlined the role of bacteria in the initiation of pulpal and periapical diseases (Bergenholtz et al. 1982, Ray & Trope 1995, Katebzadeh et al. 1999, Trope et al. 1999). It is therefore necessary to consider whether other factors (tooth isolation, use of disinfecting medications such as formalin derivates, etc.) may explain the success rate, despite the poor quality of the fillings. However, almost one-quarter of the root-filled roots had apical pathology, which translates into an important health risk. The quality of the seal performed with the coronal restoration is one of the factors which is significantly associated with failure of endodontic treatment (Ray & Trope 1995). Our study confirms these results, since 33.3% of the root-filled roots without coronal restoration showed significantly more periapical pathology (P < 0.001, 2) compared to those with restorations. Overall, 28.6% of the roots having a post were associated with periapical disease (P < 0.001, 2). These findings are in the range of other studies (Kvist et al. 1989: 16%; Buckley & Spångberg 1995: 26.9%; Saunders et al. 1997: 77%).


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