Department of Public Health, Department of Conservative Dentistry and Endodontics, and Department of Biomaterials, Laboratory of Dental Biomaterials and Experimental Odontology, University of Nice, Sophia, Antipolis, France.
Aim.
The aim of this study was to determine the periapical status and the quality of root-canal treatment amongst an adult population attending the dental school in Nice, France during 1998.
Conclusions.
Within the constraints of this study, the results demonstrated that adequate root fillings (no voids, obturation within 2 mm of the radiographic apex) was associated with fewer periapical lesions. Adequate root fillings were observed in only 32% of root-filled teeth.
Department of Public Health, Department of Conservative Dentistry and Endodontics, and Department of Biomaterials, Laboratory of Dental Biomaterials and Experimental Odontology, University of Nice, Sophia, Antipolis, France.
Introduction.
According to the European Society of Endodontology (1994), the assessment of endodontic treatment requires clinical as well as radiographical follow-ups at regular intervals. The radiographic evidence of a success is the presence of a normal periodontal ligament space around the root. If radiographs reveal that a lesion has remained the same or has only diminished in size, the treatment is not considered a success (European Society of Endodontology 1994). The prevalence and technical quality of root fillings are difficult to access epidemiologically (Imfeld1991), because the taking of radiographs for epidemiological reasons only is not accepted in many countries. The available studies dealing with this topic show large numbers of poorly executed root fillings, resulting in either the development, persistence or recurrence of periapical pathology. Results of these studies are shown in Table 1. Attention has been focused on the prevalence and the technical quality of root fillings through the evaluation of intraoral (Odesjoet al. 1990, Eriksen & Bjertness 1991, Imfeld 1991, Soikkonen 1995, Saunders et al. 1997,Weiger et al.1997, Sidaravicius et al.1999) or panoramic radiographs (De Cleen et al. 1993, Marques et al. 1998, De Moor et al. 2000).
Information about the prevalence and technical standard of root-canal treatment, and the occurrence of periapical lesions in France are scarce. This study was designed to determine retrospectively the periapical status, the prevalence and the quality of root-canal fillings in individuals seeking examination and treatment in a French dental school.
Table 1. Prevalence and radiographic quality of root-canal treatment and the prevalence of periapical radiolucencies according to previous studies.
Study population.
A comprehensive epidemiological survey involved each adult (>20-year-old) who attended the dental school in Nice, France for the first time in1998. Patients with nine or less remaining natural teeth and those who received dental care in the last 2 years were excluded. The teeth with a root resection or hemisection were also discarded. This resulted in a total of 344 orthopantomograms that created the basis for detection of root-filled teeth and periapical pathosis.
Radiographs.
The panoramic radiographs used in this study were taken by a trained radiology assistant using an orthopantomograph machine (PM 2002 CC Proline, Planmeca, Helsinki, Finland) and Kodak dental films (T - MATG, Kodak, NewYork, USA).All films were processed in a XR 24Novamachine (DuurDental, Bietigheim, Germany) using Duur Dental developer and fixer.
Evaluation of root fillings and periapical condition.
The viewing conditions were standardized, using a view box with fixed light intensity. The incidence of root fillings was recorded along with the periapical status of all teeth with the exception of third molars. Teeth were categorized as root filled if there was radiopaque material in the pulp chamber and/or in one or more root canals. A widening of the periodontal ligament space of twice the width of the lateral periodontal space or a radiolucency in connection with the apical part of the root was considered as a periapical lesion. The length of root filling was judged as ‘adequate’ if the root filling was 2 mm or less from the radiographic apex. When it was more than 2 mm from the apex, it was considered as an ‘under filling’ and when excess filling was beyond the radiographic apex it was categorized as an ‘over filling’. The density of root filling was judged as ‘adequate’ if the radiodensity of fill was uniform and appeared to be radiographically adapted to the root-canal walls. It was scored as ‘inadequate’ if the canal space was visible or if the radiodensity was not uniform. Because of superimposition of anatomical structures, teeth that could not be properly categorized were excluded. Multirooted teeth were scored according to the root with the most severe periapical status. If this tooth had been root filled, the quality of the corresponding root filling was assigned to the tooth. The data collected were examined by age, gender, tooth type and technical quality of root filling and compared to the frequency of radiographically visible periapical disease.
The interpretation of radiographs was performed independently by two examiners. Prior to this study, 20 panoramic radiographs not included in the survey were used to calibrate the two examiners. The examiner variability was determined by calculating Kappa (k) values for detecting a periapical radiolucency and for evaluating the density and periapical extension of the rootcanal filling. In case of disagreement, the two observers came to a consensus. Intraexaminer agreement was determined by rescoring 20 radiographs at least 3 months after the original examination anova, Fisher’s PLSD and Chi-square tests were used for statistical evaluation of the results. A P < 0.05was considered statistically significant.
Of the 344 patients, 164 were male (48 _14 years old) and 180 female (47 _14 years old). Of the 7840 teeth, 279 were excluded because of inadequate technical quality of the radiographs, leaving 7561 teeth available for periapical evaluation (Table 2). Males had fewer natural remaining teeth than females (22.26 _ 4.42 vs. 23.25 _3.99) (P < 0.03). Similarly, the average number of root-filled teeth was lower for men (3.59 _3.09 vs. 4.68 _3.84) (P < 0.01).
The total number of root-filled teeth was1429 (18.9%). Table 3 shows the prevalence of previous root-canal treatment according to tooth type. Teeth in the maxilla were more frequently root filled (61.9%) than teeth in the mandible (38.1%) (P < 0.0001). The teeth with the highest incidence of root-canal treatment were maxillary premolars (22.2%), followed by maxillary and mandibular molars; the mandibular incisors were the least root filled (2.5%).
Only 31.2% of the root-canal treatments were ‘adequate’. Adequate density of the canal filling was observed in58.9%of cases and the length of root filling was correct in 38.7% of teeth (Table 4).
The distribution of periapical radiolucencies is presented in Tables 5 and 6. In total, 553 teeth with periradicular lesions were observed, corresponding to an overall prevalence of 7.3%.Arranged by tooth type, maxillary (14.8%) and mandibular molars (13.5%) had the highest incidence of periapical disease (P < 0.0001). Teeth without root fillings in the maxilla had more periradicular lesions than similar teeth in the mandible, whatever the age group (P < 0.0001). Radiographically observed periapical pathology was found significantly more often in root-filled teeth (31.5% vs. 1.7%) (P < 0.0001). Amongst root-filled teeth, lesions were observed most often in maxillary molars (41.4%) and in mandibular incisors (40%) (P < 0.0001). Overall 45.3% of the poor quality root fillings had periapical lesions; the frequency of periapical bone destruction ranged from 12.7% (under filling - adequate density) to 66.7% (over filling - inadequate density). For good root fillings, the association with periapical lesions decreased to 3.8%.
Table 2. Missing, eliminated and observed teeth according to tooth type.
Table 3. Distribution of examined and root-filled teeth by sex and tooth type.
Table 4. Radiographic quality of root fillings.
Table 5. Teeth with periapical radiolucencies by age and sex distribution.
Table 6. Frequency of periapical radiolucencies by tooth type.
Patients with nine or fewer remaining teeth were excluded (De Cleen et al. 1993) because they often had periodontal disease and it was impossible to determine the role played by the endodontic treatment in the occurrence of a periapical radiolucency.
Radiographs provide only a static image of a dynamic process; a periapical lesion may be either increasing in size or healing. To limit this bias, patients who received dental treatment during the previous 2 years were excluded. Little is known about the absolute diagnostic value of a single periapical view of a root-filled tooth (Seltzer 1988). However, Petersson et al. (1991) showed that the number of endodontically treated teeth with periapical lesions that healed was comparable with the number of root-filled teeth that developed a periapical lesion during the same period. Thus, cross-sectional studies can provide reliable information on the long-term success rate of root-canal treatment within a given population. Moreover, apart from waiting to evaluate its therapeutic effect, the only way of judging the quality of a root-canal filling is to assess its radiographic appearance. Therefore, this study can only establish the association between previous endodontic treatment and the observation of periapical pathology.
Panoramic radiographs are often used in epidemiological studies. The fact that all teeth can be seen on one radiograph, the relatively low patient radiation dose and the convenience and speed with which these kind of radiographs can be exposed, are advantageous when compared with full-mouth sets of periapical radiographs. Previous studies have also used panoramic radiographs (De Cleen et al. 1993, Marques et al. 1998, De Moor et al. 2000). Moreover, several studies have examined the sensitivity of panoramic radiographs compared with full-mouth surveys (FMS) using intraoral periapical radiographs. Ahlqwist et al.1986) found that the panoramic radiograph, when used for the detection of osteolytic lesions, had a sensitivity of 76% compared with the FMS in the case of single-rooted teeth and a sensitivity of 90% in the case of multirooted teeth. Another study showed that interobserver variability was greater when looking at panoramic radiographs than when looking at the FMS (Grondahl et al. 1970). Muhammed et al. (1982) found no statistically significant difference between the panoramic radiograph and the FMS in the detection of periapical lesions. Besides, improvements in radiographic images could account for the increase in detection of periapical lesions, despite the frequent blurring of the anterior teeth. Therefore, the panoramic radiograph could be considered as an acceptable diagnosis tool for the detection of periapical lesions (Molander et al.1993).
In our study, inter- and intraexaminer agreements were high, probably because of prior calibration. All radiographs interpreted in this study were judged to be of high quality, even if some distortion may have occurred. Also, the risk of false-negative readings in the assessment of voids in the fillings does exist. Therefore, as in the study of De Cleen et al. (1993), some teeth (279) were excluded because they could not be categorized owing to difficulties in radiographic interpretation. This could have affected the results because the eliminated teeth were mainly maxillary molars, premolars and mandibular incisors; the frequency of root fillings in these teeth might have been underestimated even if the proportion of eliminated teeth (3.5%) remained acceptable.
The current investigation provides data that could be compared to those obtained from several other European studies (Petersson et al. 1986, Odesjoet al. 1990, Imfeld 1991, De Cleen et al. 1993, Saunders et al. 1997,Weiger et al.1997). The total percentage of root-filled teeth (18.9%) was high compared to some of the figures found in other countries (Table 1). This phenomenon can be explained by the fact that firstly, the survey population was not representative of the whole country. The patients who consult the dental school usually come from low socio-economic backgrounds and generally have poorer oral health (Bourgeois et al. 1997). Secondly, the differences in health care services in the various countries could account for these discrepancies. In Northern European countries, dental care is free for everyone or at least for those whose income is under the level fixed by the Public Health Insurance (Chen et al. 1997). In France, health insurance is compulsory for everyone, whatever their income. It reimburses 70% of dental care at a fixed basic rate for each treatment and the remaining 30% must be paid for by the patients, unless they have complementary insurance. Treatment carried out by the few available endodontic specialists in France is expensive and is only reimbursed at the basic rate. Lastly, the variations in age stratification of the patient samples in the various studies is likely to contribute to these differences. Older patients usually have more root-filled teeth (Eriksen1991), probably because of the longer exposure to caries and subsequent operative procedures may lead to an increased need for root-canal treatment. Our patients were older than those in a Portuguese survey which revealed only 1.5% of root-filled teeth (Marques et al. 1998), or in the Dutch study (De Cleen et al. 1993). Indeed, our findings were closer to the results of Imfeld (1991) which were obtained from an elderly population. Likewise, our study showed rather higher frequencies of periapical lesions compared with other studies (Odesjo et al. 1990, Eriksen 1991, De Cleen et al. 1993, Weiger et al. 1997, Marques et al.1998).
The percentage of periapical lesions associated with nonroot-filled teeth is comparable with those of other countries (Eriksen1991, Weiger et al.1997, Marques et al. 1998, Sidaravicius et al. 1999). These other studies showed that technically satisfactory endodontic treatment was performed in only 30-40% of the cases. Our results corroborate these findings because using both the apical extent and the density of the root-canal filling as a criterion for evaluating the quality of the root-canal treatment, 68.8% of the root fillings were found to be poorly executed.
All epidemiological surveys have shown a significantly higher frequency of periapical lesions in root-filled teeth (Odesjo et al.1990, Eriksen 1991, Imfeld et al. 1991, De Cleen et al. 1993, Buckley & Spangberg 1995, Soikkonen 1995, Saunders et al. 1997,Weiger et al. 1997, Marques et al. 1998, Sidaravicius et al. 1999, De Moor et al. 2000). In numerous surveys, more than half of the root-filled teeth were judged as inadequately filled (Odesjo et al. 1990, Imfeld et al. 1991, Soikkonen et al. 1995, Weiger et al. 1997, Sidaravicius et al. 1999). Allard & Palmquist (1986) found no difference between the maxilla and the mandible in the average percentage of teeth with periapical lesions, yet the percentage of root-filled maxillary teeth was twice that of root-filled mandibular teeth. In our study, maxillary teeth were also root filled more frequently than mandibular teeth. However, the maxilla was found to have almost twice as many periapical lesions as the mandible (Buckley et al. 1995). Periapical lesions were most frequently associated with molars and mandibular incisors. This could be explained by the complex anatomy of these teeth. Our finding that mandibular root-filled incisors had a higher prevalence of periapical lesions than posterior root-filled teeth is supported by findings of other studies (Strindberg 1956, Grahnen & Hansson 1961).
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