ORIGINAL Oginni ARTICLE et al
Root Canal Treatment and Prevalence of Apical Periodontitis in a Nigerian Adult Subpopulation: A Radiographic Study Adeleke O. Oginnia/Adeyinka A. Adelekeb/Nicholas P. Chandlerc
Purpose: To evaluate the frequency, distribution and quality of root canal treatment in an adult Nigerian subpopulation and to determine the prevalence of apical periodontitis. Materials and Methods: The periapical status and length of root fillings of 756 patients attending Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria for the first time were evaluated using full mouth periapical radiographs. The length of the root canal filling was considered ‘adequate’ if it was ≤ 2 mm from the radiographic apex, ‘underfilled’ if it was > 2 mm short of the apex, and ‘overfilled’ if filling material extended beyond the radiographic apex. Periapical status was assessed using the periapical index (PAI) with teeth classified as having apical periodontitis if the score was over 2. Results: Overall, 61.2% of the patients had root-filled teeth and 67.2% featured apical periodontitis. Of the 21,468 teeth examined, 12.2% had been root filled, and of these 41% exhibited apical periodontitis. The prevalence of rootfilled teeth was higher in the younger patients, while the prevalence of apical periodontitis in root-filled teeth was similar between age groups. Root-treated teeth that were overfilled or were mandibular incisors had the highest prevalence of apical disease. Overfilled teeth were more prone to developing an apical radiolucency than were underfilled teeth (P < 0.001 and P < 0.05, respectively). Conclusions: The prevalences of endodontically treated teeth and apical periodontitis were within the range reported for other countries; however, a very large number of patients required treatment or retreatment. Key words: apical periodontitis, root canal treatment Oral Health Prev Dent 2015;13:85-90 doi: 10.3290/j.ohpd.a31661
A
pical periodontitis is an inflammation of the periodontium at the portals of entry of the root canal system. Lesions are typically located at the root apex but may develop laterally and at furcations (Huumonen and Ørstavik, 2002). Apical periodontitis is considered to be a sequela of caries and its treatment or dental trauma (Aleksejuniene a
Associate Professor, Department of Restorative Dentistry, Faculty of Dentistry, Obafemi Awolowo University, Ile-Ife, Nigeria.
b
Hospital Consultant, Department of Dental Surgery, Ekiti State University Teaching Hospital, Ado-Ekiti, Nigeria.
c
Associate Professor, Department of Oral Rehabilitation, University of Otago School of Dentistry, Dunedin, New Zealand.
Correspondence: Adeleke O. Oginni, Department of Restorative Dentistry, Faculty of Dentistry, Obafemi Awolowo University, Ile-Ife, 220005, Nigeria. Tel: +234-80-6445-9618. Email: adelekeoginni@ yahoo.co.uk or
[email protected]
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Submitted for publication: 28.03.12; accepted for publication: 14.05.13
et al, 2000). It is usually chronic in nature and often develops without any subjective symptoms for the patient, so that dental radiography plays an important role in diagnosis. Studies report a high prevalence of apical periodontitis in many Western societies. Prevalence values ranging from 30% to 70% have been reported from Scandinavian (Eriksen et al, 1995), European (Imfeld 1991; De Cleen et al, 1993) and North American populations (Buckley and Spangberg 1995). The prevalence increases with age (Eriksen et al, 1993; Buckley and Spangberg 1995). It may be concluded that apical periodontitis is endemic in many Western societies and constitutes a dental health problem affecting large parts of different populations (Eriksen 1991; Kirkevang and Wenzel 2003).
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In Western population groups with regular dental care habits and a restorative attitude among dentists and patients, the majority of apical lesions are found related to root-filled teeth (Eriksen et al, 1988; Odesjö et al, 1990). A slightly lower prevalence of apical periodontitis was reported in a population group where only a minority seeks regular dental care, with less than 20% of apical lesions found in connection with root-filled teeth (Marques et al, 1998). Endodontic epidemiology is, however, important to gain a complete picture of diseases, their treatment and treatment outcome in different population groups. Information about endodontic conditions from African countries is very limited. Healthcare systems are likely to influence endodontic treatment and the prevalence of apical periodontitis within the community (Eriksen et al, 2002). In Nigeria, a national health insurance scheme was inaugurated in 2006/2007, but endodontic treatment is not covered. There are about 5,000 registered dentists in the country and 50 endodontists. The specialists have been trained overseas or in local residency programmes. Many practices are limited to major cities and university teaching hospitals. Most endodontic treatment is performed by general dentists, and with more people retaining their teeth, the number of root-filled teeth is increasing. The purpose of this study was to determine the prevalence and quality of root-canal treated teeth and the prevalence of teeth with radiographically detectable periapical lesions in a Nigerian adult subpopulation.
Root canal fillings present and the periapical status of all teeth were recorded, except for the third molars. Teeth were categorised as root treated if they had radiopaque material in the pulp chamber and/or in 1 or more root canals. The length of the root canal filling was considered ‘adequate’ if it was ≤ 2 mm from the radiographic apex. If radiopaque material was > 2 mm short of the apex, the root canal filling was classified as ‘underfilled’. When filling material extended beyond the radiographic apex, it was categorised as ‘overfilled’. The periapical status was assessed using the Periapical Index (PAI), which involves an ordinal scale of 1–5 with descriptors ranging from ‘healthy’ to ‘severe periodontitis with exacerbating features’. A tooth was classified as periapically healthy if the assigned score was 1 or 2, and as having apical periodontitis if the PAI score was 3, 4 or 5. Multirooted teeth were scored according to the root with the most severe periapical status, and if root-filled, only the length of the filling in the root with the most advanced lesion was assessed. A single observer (AOO) was calibrated before evaluating the radiographs. Intra-observer agreement for the PAI scores was assessed by calculating Cohen’s kappa after re-examining a random sample of 20 of the radiographs one month later. Data collected were analysed using SPSS for Windows version 11.0 (SPSS; Chicago, IL, USA). Results were expressed as percentages and, where applicable, subjected to the chi-square test, with a P-value ≤ 0.05 set as significant.
MATERIALS AND METHODS
RESULTS
The study sample involved 756 patients attending the Oral Diagnosis Unit of the Dental Hospital, Obafemi Awolowo University Teaching Hospital Complex at Ile-Ife, Nigeria for the first time between January 2009 and June 2011. Patients younger than 20 years and those that did not have fullmouth periapical radiographs were excluded. All gave their informed consent. A Uni-Grip 360 film holder/beam alignment device was used to assist with the long-cone paralleling radiography technique (Dentsply Rinn; Elgin, IL, USA). Radiographs were taken using a Best-X-DC unit (New Life Radiology; Grugliaso, Italy) on RDX-58 E films (Primax; Berlin, Germany) which were processed automatically. They were assessed on an X-ray viewer in a darkened room using a 2X magnifying lens and a metal endodontic ruler.
Of the 756 patients that participated, 414 were male (48 ± 10.7 years) and 342 female (45 ± 12.6 years). The mean number of natural teeth remaining per subject was 28.4 ± 3.4 and the mean number of root-filled teeth was 3.5 ± 2.3 (Table 1). The mean number of remaining natural teeth and of root-filled teeth decreased with age. The intra-observer score yielded a kappa value of 0.85, i.e. very good agreement (Landis and Koch 1977). Four hundred sixty-three patients (61.2%) had root-filled teeth and 508 patients (67.2%) exhibited apical periodontitis on one or more teeth. The total number of teeth examined was 21,468, of which 2,625 (12.2%) were root filled. Forty-one percent (1068) of the treated teeth had apical periodontitis. The number of teeth without root canal fillings but with apical periodontitis was 2015 (10.7%) (Table 2).
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Table 1 Mean number of teeth present and root-filled teeth according to age group No. of patients Age group
Male
Female
Total
Mean no. of teeth present*
Mean no. of root-filled teeth*
20–29
103
64
167
29.6 ± 2.6
5.8 ± 2.6
30–39
125
80
205
29.3 ± 1.2
5.2 ± 2.3
40–49
65
73
138
28.4 ± 3.1
4.3 ± 1.5
50–59
89
64
153
25.5 ± 4.3
3.6 ± 2.4
≥60
32
61
93
21.7 ± 5.2
2.8 ± 3.6
Total
414
342
756
28.4 ± 3.4
3.5 ± 2.3
*Mean ± SD
Table 2 Prevalence of apical radiolucency in non root-filled and root-filled teeth by age group No. of non root-filled teeth
No. of root-filled teeth †
Total
20–29
3,795
483 (12.7)
728 (16.1)
325 (44.6)
30–39
3,846
457 (11.9)
673 (14.9)
278 (41.3)
40–49
3,960
428 (10.8)
525 (11.7)
207 (39.4)
50–59
4,269
328 (7.7)
413 (8.8)
159 (38.5)
≥60
2,973
319 (10.7)
286 (8.8)
99 (34.6)
Total
18,843
2015 (10.7)
2625 (12.2)
1068 (40.7)
Apical periodontitis
†
Numbers in parenthesis are percentages of total number of non root-filled teeth. root-filled teeth.
The prevalence of root-filled teeth was higher in the younger than in the older age groups. 16.1% of teeth in the age group 20–29 had been root treated compared to 8.8% each in the 50–59 and ≥ 60 age group (Table 2). The prevalence of apical periodontitis in root-filled teeth was similar between age groups. Teeth in the maxilla were significantly more frequently root-filled (14.2%) than those in the mandible (10.0%; Table 3) (P < 0.001, OR = 1.49, 95% CI = 1.37–1.62). In the maxilla, the most frequently root-filled tooth was the central incisor (405, 26.5%) followed by the lateral incisor (281, 16.0%) and the first molar (206, 12.6%). In the mandible, the first molar (301, 25.0%) was the most frequently rootfilled tooth, followed by the first (209, 13.7%) and second premolars (195, 15.7%). As seen in Table 3, the mandibular canines and incisors were less frequently filled than any other tooth type. Although many of the root-filled maxillary central incisors 180 (44.4%), lateral incisors 146 (52.0%) and mandibular first molars 135 (44.7%) had apical
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Total
Apical Periodontitis‡
Age group
‡
Numbers in parenthesis are percentages of total number of
periodontitis, the mandibular lateral incisors had the highest percentage of root-filled teeth with apical periodontitis (56.6%), followed by the mandibular central incisors (53.9%, Table 3). As shown in Table 4, the number of teeth that were adequately filled was 1575 (60.0%), 216 (8.2%) were underfilled and 834 (31.8%) overfilled. An apical radiolucency was observed most often in overfilled teeth (61.5%), followed by underfilled teeth (38.4%) and then adequately filled teeth (30.0%). Overfilled teeth were more prone to developing an apical radiolucency than underfilled teeth (P < 0.001 and P < 0.05, respectively).
DISCUSSION The prevalence of root-filled teeth in the Nigerian subpopulation in this study (61.2%) falls within the range (34%–84%) previously reported for populations in other countries (Sidaravicius et al, 1999;
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Table 3 Prevalence of root filling and apical periodontitis according to tooth type No. of non root-filled teeth Tooth type
No. of root-filled teeth †
Total (%)*
Apical periodontitis (%)
Total (%)*
Apical periodontitis (%)‡
Maxilla Central incisors
1,204 (5.6)
326 (27.1)
405 (25.2)
180 (44.4)
Lateral incisors
1,471 (6.8)
487 (33.1)
281 (16.0)
146 (52.0)
Canines
1,534 (7.1)
76 (5.0)
138 (8.3)
58 (42.0)
First premolars
1,232 (5.7)
54 (4.4)
184 (13.0)
70 (38.0)
Second premolars
1,481 (6.9)
48 (3.2)
207 (12.3)
75 (36.2)
First molars
1,434 (6.7)
232 (16.3)
206 (12.6)
78 (37.9)
Second molars
1,328 (6.2)
51 (3.8)
153 (10.3)
59 (38.6)
9,684 (45.1)
1,274 (13.2)
1,604 (14.2)
666 (41.5)
Central incisors
1,559 (7.3)
73 (4.6)
65 (4.0)
35 (53.9)
Lateral incisors
1,710 (8.0)
35 (2.1)
53 (3.0)
30 (56.6)
Canines
1,560 (7.3)
30 (1.9)
34 (2.1)
10 (29.4)
First premolars
1,310 (6.1)
154 (11.8)
209 (13.7)
90 (43.1)
Second premolars
1,058 (4.9)
168 (15.9)
195 (15.7)
52 (26.7)
904 (4.2)
185 (20.5)
301 (25.0)
135 (44.9)
Second molars
1,058 (4.9)
96 (9.1)
164 (13.4)
50 (30.5)
Subtotal
9,159 (42.7)
741 (8.1)
1,021 (10.0)
402 (39.4)
Subtotal Mandible
First molars
*Percentage of number of teeth examined. †Percentage of total number of non-root-filled teeth. ‡Percentage of total number of root filled teeth.
Table 4 Correlation between quality of endodontic treatment and periapical status Periapical status Number of teeth (%)
Adequate [A]
1,575 (60.0)
1,103 (70.0)
472 (30.0)
834 (31.8)
321 (38.5)
513 (61.5)
< 0.001
216 (8.2)
133 (61.6)
83 (38.4)
< 0.05
2,625 (100.0)
1,557 (59.3)
1,068 (40.7)
Inadequate (overfilling) [B] Inadequate (underfilling) [C] Total 2
Normal periapical tissue
Apical periodontitis
P-value
Quality of endodontic treatment
2
A vs B, r = 224.5; d.f. = 2; P < 0.001. A vs C, r = 6.4; d.f. = 2; P < 0.05.
Kirkevang et al, 2001a; Dugas et al, 2003). The difference may be a result of different healthcare systems. In countries where individuals are covered by some form of insurance, such as Japan, the prevalence of root canal treatment was reported to be high, i.e. 87% (Midori et al, 2005). The cost of root canal treatment may also affect the prevalence of root-filled teeth. Until recently, tooth extraction was
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more popular than root canal treatment in Nigeria, but this trend is changing. There are still many challenges; the recently introduced national health insurance scheme for federal government employees does not cover endodontic treatment. Endodontic treatment is carried out mostly at university teaching hospitals, some state specialist hospitals and some private hospitals located in major cities. The
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cost is about 3 and 5 times more than tooth extraction in teaching hospitals and private hospitals, respectively. Root canal treatment of a molar costs 2 or 3 times more than that of a central incisor. In this study, the prevalence of root-filled teeth was higher in younger patients. This is contrary to the findings of previous studies, where the increased frequency of root-filled teeth in the older age group was attributed to a longer exposure to caries, attrition and operative procedures (Hugoson et al, 1986; Bergstrom et al, 1987; Odesjö et al, 1990). In this study, more root canal fillings were carried out on anterior teeth following traumatic injuries, which are more common in younger age groups (Moule and Moule, 2007). It may also be that younger patients seek dental treatment more frequently than older individuals; irrespective of financial factors, they care more about their teeth. When comparing the results of epidemiological studies, the variability of the evaluation criteria for apical periodontitis should be considered. Some studies (De Cleen et al, 1993; Buckley and Spangberg 1995) recorded apical periodontitis when the apical periodontal ligament space was widened or the lamina dura was lost. These criteria are prone to subjectivity and bias, affecting the results. The PAI system provides measurable criteria which are mutually exclusive, meaningful and reproducible (Ørstavik et al, 1986). In the present study, as in others, the PAI system was used and scores of 3–5 were considered as ‘diseased’ or having apical periodontitis (Eriksen et al, 1995; Marques et al, 1998; Sidaravicius et al, 1999). A potential limitation of the study is that a very small number of teeth exhibited radiographic evidence of a pulpotomy or the operator’s best efforts at accessing root canal orifices; these had to be scored as root canal fillings. Also, as a radiographic study without clinical examination of the patients, the potential for endodonticperiodontic lesions could not be explored. A true combined endodontic-periodontal lesion may occur when an endodontically induced periapical lesion exist at a tooth that is also affected by marginal periodontitis. These two lesions can either merge or exist separately. Merged lesions form by ongoing marginal attachment loss or by exacerbations of apical periodontitis (Zehnder et al, 2002). The prevalence of apical radiolucencies in root filled teeth (41%) in the present study is within the range of 16%–65% reported by other countries (De Cleen et al, 1993; Weiger et al, 1997; Sidaravicius et al, 1999; Jimenez-Pinzon et al, 2004; Midori et al, 2005). This may suggest that root-filled teeth in
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Nigerians have a similar risk of developing an apical radiolucency. The comparison is possible because the subjects in this study were first-time adult patients presenting at a university teaching hospital and their recruitment was similar to that performed in other studies (Lupi-Pegurier et al, 2002; Dugas et al, 2003; Jimenez-Pinzon et al, 2004). A radiographically detected apical lesion was associated with 10.7% of non-root-filled teeth in the present study. This figure is much higher than the 1.5%, 2.9% and 3.8% reported in Japan, Sweden and Belgium, respectively (Eckerbom et al, 1987; De Moor et al, 2000; Midori et al, 2005). This finding revealed a much greater level of unmet treatment need among the Nigerian subpopulation group studied. The prevalence of apical radiolucency in all teeth examined was 14.4%. This figure is higher than reported in similar studies – 4.1% in the United States (Buckley and Spangberg, 1995), 6.0% in the Netherlands (De Cleen et al, 1993) and 4.9% in the United Kingdom (Saunders et al, 1997) – indicating that the chance of detecting an unexpected periapical lesion in the average Nigerian patient is very high. There is a substantial treatment need in the population examined. Similar to the findings of previous studies, the rootfilled mandibular incisors had the highest percentage of apical periodontitis (Lupi-Pegurier et al, 2002; Midori et al, 2005) and this may be due to the complex anatomy of these teeth, which often have more than one root canal (Laws 1971; Kaffe et al, 1985). The length of the root canal filling was found to be adequate in 60% of the teeth. This is a little higher than the ranges of 46%–58% reported elsewhere (De Moor et al, 2000; Kirkevang et al, 2001b; Dugas et al, 2003). The present study was carried out at a university teaching hospital, where most of the treatment was done, so caution must be exercised when extrapolating this result to the general population. Root fillings extending beyond the radiographic apex were more frequently associated with an apical radiolucency, in agreement with the results of other authors (De Moor et al, 2000; Dugas et al, 2003). More underfilled teeth (38%) had an apical radiolucency than those with adequate fillings (30%), which is contrary to the result of Odesjö et al (1990). Statistical analysis revealed that overfilled teeth are significantly more prone to develop an apical radiolucency than underfilled teeth, P < 0.001 and P < 0.05, respectively. Other factors such as canal disinfection before filling, quality of filling and the coronal restoration may have influenced the development of apical periodontitis in the root-filled teeth. These factors will be examined in a future study.
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CONCLUSIONS The prevalences of endodontically treated teeth and apical periodontitis in the Nigerian subpopulation studied were within the range reported for other countries. The prevalence of root-filled teeth was higher in the younger patients, while the prevalence of apical periodontitis in root-filled teeth was similar between age groups. The data demonstrated that a very large number of patients required root canal treatment or retreatment.
REFERENCES 1. Aleksejuniene J, Eriksen HM, Sidaravicius B, Haapasalo M. Apical periodontitis and related factors in an adult Lithuanian population. Oral Surg Oral Med Oral Pathol Oral Radiol Endodont 2000;90:95–101. 2. Bergstrom J, Eliasson S, Ahlberg KF. Periapical status in subjects with regular dental care habits. Community Dent Oral Epidemiol 1987;15:236–239. 3. Buckley M, Spangberg LSW. The prevalence and technical quality of endodontic treatment in an American subpopulation. Oral Surg Oral Med Oral Pathol Oral Radiol Endodont 1995;79:92–100. 4. De Cleen MJH, Schuurs AHB, Wesselink PR, Wu M-K. Periapical status and prevalence of endodontic treatment in an adult Dutch population. Int Endodont J 1993;26: 112–119. 5. De Moor RJG, Hommez GMG, De Boever JG, Delme KIM, Martens GEI. Periapical health related to the quality of root canal treatment in a Belgian population. Int Endodont J 2002;33:113–120. 6. Dugas NN, Lawrence HP, Teplitsky PE, Pharoah MJ, Friedman S. Periapical health and treatment quality assessment of root-filled teeth in two Canadian populations. Int Endodont J 2003;36:181–192. 7. Eckerbom M, Andersson J-E, Magnusson T. Frequency and technical standard of endodontic treatment in a Swedish population. Endod Dent Traumatol 1987;3:245–248. 8. Eriksen HM. Endodontology-epidemiologic considerations. Endod Dent Traumatol 1991;7:189–195. 9. Eriksen HM, Berset GP, Hansen BF, Bjertness E. Changes in endodontic status 1973–1993 among 35-year-olds in Oslo, Norway. Int Endodont J 1995;28:129–132. 10. Eriksen HM, Bjertness E, Orstavik D. Prevalence and quality of endodontic treatment in an adult urban population in Norway. Endod Dent Traumatol 1988;4:122–126. 11. Eriksen HM, Kirkevang LL, Petersson K. Endodontic epidemiology and treatment outcome: general considerations. Endodont Topics 2002;2:1–9. 12. Hugoson A, Koch G, Bergendahl T, Hallonsten AL, Laurell L, Lundgren D, et al. Oral health of individuals aged 3–80 years in Jönköping, Sweden, in 1973 and 1983. II. A review of clinical and radiographic findings. Swed Dent J 1986;10:175–194. 13. Huumonen S, Ørstavik D. Radiological aspects of apical periodontitis. Endodont Topics 2002;1:3–25.
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14. Imfeld TN. Prevalence and quality of endodontic treatment in an elderly, urban population of Switzerland. J Endodont 1991;17: 604–607. 15. Jimenez-Pinzon A, Segura-Egea JJ, Poyato-Ferrera M, Velasco-Ortega E, Rios-Santos JV. Prevalence of apical periodontitis and frequency of root-filled teeth in an adult Spanish population. Int Endodont J 2004;37:167–173. 16. Kaffe I, Kaufman A, Littner MM, Lazarson A. Radiographic study of the root canal system of mandibular anterior teeth. Int Endodont J 1985;18:253–259. 17. Kirkevang L-L, Wenzel A. Risk indicators for apical periodontitis. Community Dent Oral Epidemiol 2003;31:59–67. 18. Kirkevang L-L, Hörsted-Bindslev P, Ørstavik D, Wenzel A. Frequency and distribution of endodontically treated teeth and apical periodontitis in an urban Danish population. Int Endodont J 2001a;34:198–205. 19. Kirkevang L-L, Hörsted-Bindslev P, Ørstavik D, Wenzel A. A comparison of the quality of root canal treatment in two Danish subpopulations examined 1974–75 and 1997–98. Int Endodont J 2001b;34:607–612. 20. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–174. 21. Laws AJ. Prevalence of canal irregularities in mandibular incisors: a radiographic study. New Zealand Dental J 1971;67:181–186. 22. Lupi-Pegurier L, Bertrand MF, Muller-Bolla M, Rocca JP, Bolla M. Periapical status, prevalence and quality of endodontic treatment in an adult French population. Int Endodont J 2002;35: 690–697. 23. Marques MD, Moreira B, Eriksen HM. Prevalence of apical periodontitis and results of endodontic treatment in an adult, Portuguese population. Int Endodont J 1998;31:161–165. 24. Midori T, Tatsuo Y, Reiko Y, Naofumi T, Tomonori S, Kohzoh T, et al. Radiographic evaluation of periapical status and prevalence of endodontic treatment in an adult Japanese population. Oral Surg Oral Med Oral Pathol Oral Radiol Endodont 2005;100:631–635. 25. Moule AJ, Moule CA. The endodontic management of traumatized permanent anterior teeth: a review. Austral Dent J 2007;1(suppl):S122–137. 26. Odesjö B, Hellden L, Salonen L, Langeland K. Prevalence of previous endodontic treatment, technical standard and occurrence of periapical lesions in a randomly selected adult, general population. Endod Dent Traumatol 1990; 6:265–272. 27. Ørstavik D, Kerekes K, Eriksen HM. The periapical index: a scoring system for radiographic assessment of apical periodontitis. Endod Dent Traumatol 1986;2:20–34. 28. Saunders WP, Saunders EM, Sadiq J, Cruickshank E. Technical standard of root canal treatment in an adult Scottish population. Brit Dent J 1997;182:382–386. 29. Sidaravicius B, Aleksejuniene J, Eriksen HM. Endodontic treatment and prevalence of apical periodontitis in an adult population of Vilnius, Lithuania. Endod Dent Traumatol 1999;15:210–215. 30. Weiger R, Hitzler S, Hermle G, Lost C. Periapical status, quality of root canal fillings and estimated endodontic treatment needs in an urban German population. Endod Dent Traumatol 1997;13:69–74. 31. Zehnder M, Gold SI, Hasselgren G. Pathologic interactions in pulpal and periodontal tissues. J Clin Periodontol 2002;29:663–671.
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