Skip to main content
NCBI home page
The Saudi Dental Journal logoLink to The Saudi Dental Journal
. 2012 May 5;24(3-4):149–155. doi: 10.1016/j.sdentj.2012.02.001

Prevalence of apical periodontitis and quality of root canal treatment in an adult Palestinian sub-population

Raed Mukhaimer a,⁎, Emad Hussein a, Ibtesam Orafi b
PMCID: PMC3729275  PMID: 23960544

Abstract

Purpose

The aim of this study was to determine the prevalence of apical periodontitis and the technical quality of root canal fillings in a Palestinian sub-population.

Methods

The panoramic radiographs of 258 patients (142 females, 116 males) attending dental clinics in 2010 were examined to identify the presence of apical lesions associated with any remaining teeth, excluding third molars. The technical quality of root canal fillings was also evaluated by assessing apical extension from the radiographic apex. The panoramic radiographs were taken by a well-trained radiology assistant and evaluated by a radiologist and an endodontist. Statistical analysis was performed with the chi-square test with a significant level set at P < 0.05%.

Results

Of 6482 teeth examined radiographically, 978 (15.1%) had radiographic signs of apical periodontitis (AP). The prevalence of AP was 8.3% in teeth without filled roots and 59.5% (509/855) in root canal-treated teeth. The prevalence of AP and endodontic treatment increased with age and differed significantly (p < 0.05) between males and females. The majority (74.5%) of root canal fillings was performed inadequately, and most (77.2%) inadequate fillings were >2 mm short of the radiographic apex. The presence of AP was correlated significantly with poorly executed root canal fillings (p < 0.05).

Conclusions

The present study found a high prevalence and incidence of AP in association with root-filled teeth. The technical quality of many root canal treatments was unacceptable.

Keywords: Apical periodontitis, Epidemiology, Radiographic evaluation, Root canal treatment

1. Introduction

Apical periodontitis (AP) is an inflammatory disorder of periradicular tissues caused by persistent microbial infection in the root canal of the affected tooth (Kakehashi et al., 1965; Sundqvist, 1992). This inflammation is frequently asymptomatic and detected primarily on routine radiographic examination. Apical inflammation is associated with expansion of the periodontal ligament space in the infected apical area. Andreasen and Rud (1972) found that moderate to severe inflammation was likely when the periodontal ligament space was doubled in width. Early-stage apical pathology may also be indicated by radiographically visible changes in the lamina dura (Barbat and Messer, 1998; Lee and Messer, 1988).

Several cross-sectional studies have highlighted the prevalence of AP, and have reported a variety of ranges for this prevalence depending on the study population and geographical area (Table 1). The reported prevalence of AP in association with root-filled teeth has ranged from 16.8% to 64.5%, and apical lesions have been found to develop around many endodontically treated teeth. Previous studies have also revealed the low quality of endodontic treatment performed by general practitioners, despite improvements in endodontic materials, instruments, and techniques (Boucher et al., 2002; Buckley and Spangberg, 1995; De Cleen et al., 1993; Eriksen and Bjertness, 1991; Marques et al., 1998; Petersson et al., 1989; Saunders et al., 1997; Sidaravicius et al., 1999; Weiger et al., 1997).

Table 1.

Summary of some previous studies of the prevalence of apical periodontitis and root canal fillings.

Author Country No. of teeth %Total AP %RCT %RCT with AP
Frisk et al. (2008) Sweden 12,433 3.3 8.5 24.6
Touré et al. (2008) Senega 6234 4.6 2.6 56.1
Sunay et al. (2007) Turkey 8863 7.0 5.2 53.5
Loftus et al. (2005) Ireland 7424 2.6 2.0 25.0
Kabak and Abbott (2005) Belarusia 31,212 12 20 45.0
Georgopoulou et al. (2005) Greece 7664 13.6 9.2 60.0
Jiménez-Pinzón et al. (2004) Spain 4453 4.2 2.0 64.5
Lupi-Pegurier et al. (2002) France 7561 7.3 18.9 31.5
Kirkevang et al. (2001) Denmark 15,984 3.4 4.8 52
De Moor et al. (2000) Belgium 4617 6.6 6.8 40.4
Sidaravicius et al. (1999) Lithuania 3892 7.2 8.2 35.0
Marques et al. (1998) Portugal 4446 2.0 1.5 21.7
Soikkonen (1995) Finland 2355 7.1 21.5 16.8
Eriksen et al. (1995) Norway 3282 0.6 1.3 38.1
Ödesjö et al. (1990) Sweden 17,430 2.9 8.6 44.7
Petersson et al. (1989) Sweden 11,497 8.9 22.8 26.5
Open in a new tab

A search of the endodontic literature revealed no study of the frequency or success rates of root canal treatment or the frequency of AP in a Palestinian population. Although a limited amount of data was obtained, it should be useful for dental health planning. This investigation aimed to assess the prevalence of apical periodontitis and the technical quality of root canal fillings in an adult Palestinian population using panoramic radiography.

2. Materials and methods

2.1. Study sample

The study sample consisted of patients from all provinces of Palestine who attended clinics at the Dental School of Arab American University for the first time in 2010. The Ministry of Health Ethics Committee approved the study. All participants provided informed consent prior to inclusion in the study.

The age of the 258 participants ranged from 17 to 62 (mean, 39) years. Subjects were divided into age groups of about 9-year intervals. Patients younger than 17 years and those with fewer than 10 remaining teeth were excluded from the study. The final sample comprised 258 panoramic radiographs of 258 patients on which apical status and root fillings were assessed.

All teeth were classified according to the Fédération Dentaire International (FDI) nomenclature. The following data were recorded on a structured form for each subject: age and sex, teeth present (excluding third molars), number and location of non-root-filled teeth with apical lesions, number and location of root-filled teeth with and without AP, and technical quality of root canal fillings (length of root filling from the radiographic apex).

2.2. Radiographs

As full-mouth apical radiographs are not used routinely in our dental school, the present study relied on panoramic radiography, which allowed the collection of a large volume of patient data in university clinics without exposing study participants to excessive radiation.

A well-trained radiology assistant took all conventional panoramic radiographs used in this study (OP 100 orthopantomograph; Instrumentarium Imaging, Tuusula Finland). All radiographs included in the analysis were of high quality, enabling the assessment of the apex, apical area, and extent of root filling of all teeth. Poor-quality panoramic radiographs, including under- or overexposed images, those with blurred anterior regions, and those obviously affected by patient movement, were excluded from the analysis. All radiographs were examined systematically in a darkened room using an illuminated viewer box with magnification (2.5×).

2.3. Examiners

One endodontist and one radiologist, both members of the conservative dentistry and endodontics department and instructors of undergraduate dental school students, served as examiners in this study. Before conducting the study, the two observers were calibrated by scoring 30 images not included in the main study. Inter-examiner agreement with regard to the detection of apical radiolucency and the apical extent of root canal filling was determined by computing Cohen’s kappa (κ = 0.82). In case of disagreement, the two observers reached a consensus. A re-evaluation performed 6 months after the original examination showed high intra-examiner agreement (κ = 0.86).

2.4. Evaluation criteria

The following radiographic scoring criteria (De Moor et al., 2000) were used to examine teeth.

2.4.1. Root canal-treated tooth

Tooth with radiopaque material in pulp chamber and/or root canal(s).

Technical quality of root canal fillings: adequate (filling 0–2 mm short of radiographic apex) or inadequate (filling >2 mm short of radiographic apex, extruding beyond radiographic apex, or limited to pulp chamber).

2.4.2. Apical status

Healthy periodontal ligament (intact, no sign of apical pathosis) or AP [widening of periodontal ligament (apical portion not exceeding 2× width of lateral periodontal ligament space) or apical radiolucency (radiolucency at root apex exceeding 2× width of lateral periodontal ligament)].

2.5. Statistical methods

All statistical analyses were performed using the SPSS software (ver. 15; SPPS, Inc., Chicago, IL, USA). The chi-square test was used to determine the relationship between the technical quality of root canal filling and the apical status and for the evaluation of teeth subgroups for the different parameters studied. P < 0.05 was considered statistically significant.

3. Results

3.1. Examined teeth

A total of 6591 teeth were examined on 258 orthopantomographs, of which 109 (1.7%) were excluded because of poor radiographic technical quality, leaving 6482 teeth available for evaluation. A mean of 25.2 (range, 15–28) teeth were examined per subject. Females comprised 55% of the population and had significantly more natural remaining teeth than males (p < 0.05). The mandibular first molars were absent most frequently (19.1%), followed by the maxillary second premolars (14.2%; Table 2).The number of missing teeth increased significantly with age (p < 0.05; Table 4).

Table 2.

Distribution of examined teeth, root-filled teeth, root-filled teeth with AP and non-root-filled teeth with AP according to tooth type.

Tooth type Examined teeth No. (%) Root-filled teeth No. (%) Root-filled teeth with AP No. (%) Non-root-filled teeth with AP No. (%)
Maxillary
 Anteriors 1477 (22.8) 184 (21.5) 92 (18.1) 104 (22.2)
 Premolars 848 (13.1) 189 (22.2) 114 (22.4) 102 (21.7)
 Molars 870 (13.5) 149 (17.4) 95 (18.7) 75 (16.0)



Mandibular
 Anteriors 1543 (23.7) 31 (3.6) 15 (3) 36 (7.7)
 Premolars 937 (14.4) 144 (16.8) 76 (15) 48 (10.2)
 Molars 807 (12.5) 158 (18.5) 117 (22.8) 104 (22.2)



Total 6482 (100) 855 (100) 509 (100) 469 (100)
Open in a new tab

Table 4.

Number and percentage of present teeth, root-filled teeth and teeth with AP according to age groups.

Age group Present teeth
 Root-filled teeth
 Root-filled teeth with AP
 Non- root-filled teeth with AP
No. % No. %a No. %a No. %a
17–24 years 1376 (21.2) 79 (5.7) 48 (61%) 67 (5.2)
25–34 years 2060 (31.8) 244 (11.9) 149 (61%) 129 (7.1)
35–44 years 1882 (29.0) 301 (16.0) 175 (58%) 135 (8.5)
45–54 years 814 (12.6) 159 (19.5) 99 (62%) 93 (14.2)
0ver 55 years 350 (5.4) 72 (20.5) 38 (53%) 45 (16.1)
Total 6482 (100) 855 (13.2) 509 (59.5%) 469 (8.3)
Open in a new tab
a

Based on teeth in age group.

3.2. Root canal treatment

Most (212/258; 82.2%) subjects had at least one endodontically treated tooth. The total number of root-filled teeth was 855 (13.2%). Females had significantly more root-filled teeth than males (484 vs. 371; p < 0.05). Previous root canal treatment was present most frequently in the maxillary first premolars (11.9%), followed by the maxillary and mandibular first molars (11.5% each; Table 2). The mandibular central incisors were treated least commonly (0.6%). Significantly more maxillary (15.9%) than mandibular (10.4%) teeth were endodontically treated (p < 0.05; Table 2). Within age groups, the incidence of root canal filling increased from one age group to the next (Table 4).

3.3. Apical status

Table 3 demonstrates the distribution of the teeth examined according to the presence of root fillings and apical radiolucencies. Intotal, 978 teeth with periradicular lesions were observed, corresponding to an overall prevalence of 15.1%. AP was more prevalent in the maxilla (18.2%) than in the mandible (12.1%). Mandibular molars (27.4%) and maxillary premolars (25.5%) had the highest incidence of apical disease, and the mandibular anterior dentition had the lowest incidence (3.3%; Table 2).

Table 3.

Distribution of examined teeth according to the apical status.

Apical status of teeth Non-root-filled teeth No. (%) Root-filled teeth No. (%) Total
With apical periodontitis 469 (8.3) 509 (59.5) 978 (15.1)
Without apical periodontitis 5158 (91.7) 346 (40.5) 5504 (84.9)



Total 5627 (100) 855 (100) 6482 (100)
Open in a new tab

AP was observed in 469 (8.3%) non-root-filled teeth (Table 3); significantly more of these teeth belonged to female subjects than male subjects (p < 0.05). Among non-filled teeth, AP was present most frequently in association with the maxillary first premolars and mandibular first molars (12.4% each), and least commonly with the mandibular canines (2.1%). In both jaws, the incidence of AP was significantly higher in posterior than in anterior teeth (p < 0.05). The prevalence of AP associated with non-root-filled teeth increased with age (Table 4).

Radiographic signs of AP were observed in 509 (59.5%) root-filled teeth. Apical lesions were associated most frequently with the mandibular first molars (14.6%) and maxillary first premolars (13.4%). AP was significantly more likely to be associated with root-filled teeth than with non-treated teeth (χ2 = 3513.11; p < 0.05).

3.4. Technical quality of root canal treatment

Table 5 shows the correlation between the radiographic technical quality of root canal fillings and radiographic signs of AP. Root-filled teeth classified as adequately filled represented only 3% of the 508 cases associated with a apical lesion. The majority (74.5%) of root canal fillings were poorly executed and most (77.2%) of these fillings were >2 mm short of the radiographic apex. The presence of AP was correlated significantly with inadequate root canal fillings (p < 0.05).

Table 5.

Correlation between radiographic quality of root canal fillings and radiographic signs of AP.

Length of the root filling RCT with AP RCT without AP No. (%) Total (%)
Adequate
(0–2 mm from the radiological apex) 16 (3) 202 (58) 218 (25.5)



Inadequate
>2 mm from the radiological apex 369 (73) 123 (36) 492 (57.5)
Extrusion of material through the apex 26 (5) 4 (1) 30 (3.5)
Material only in the pulp chamber 97 (19) 18 (5) 115 (13.5)



Total 508 (100) 347 (100) 855 (100)
Open in a new tab

4. Discussion

The prevalence of AP and technical quality of root canal treatment have been examined in patient populations selected using a variety of approaches. The sample examined in this study consisted of patients who visited the Dental School at Arab American University in Palestine for the first time to obtain routine dental care. Several other studies screened dental school patients on the same basis (De Moor et al., 2000; Jiménez-Pinzón et al., 2004; Lupi-Pegurier et al., 2002; Sunay et al., 2007; Touré et al., 2008). However, because our subjects did not represent a random sample of the Palestinian population, but instead consisted of individuals seeking very inexpensive dental treatment, the extrapolation of our results to the general population must be done with caution.

Like that of Lupi-Pegurier et al. (2002), our study sample included more female than male subjects, which may reflect a gender difference in the interest in obtaining dental care.

Several epidemiological studies have been conducted in different countries using apical and/or panoramic radiographs (Table 1) as the method of choice for evaluating AP and the technical quality of endodontic treatment. We used panoramic radiographs in this study because of their availability, as full-mouth apical radiographs were not routinely taken in our dental school. Lupi-Pegurier et al. (2002, p.6) reported that “the fact that all teeth can be seen and interpreted on a single radiograph, the speed and convenience with which these radiographs are taken and processed and the relatively reduced patient radiation dose are advantageous when compared with full-mouth apical radiographs.” Studies have also found no significant difference between the sensitivities of panoramic and full-mouth apical radiographs in the detection of periapical lesions (Ahlqwist et al., 1986; Muhammed and Manson-Hing, 1982). In addition, modern panoramic machines produce better-quality radiographic images, even in the anterior region. Therefore, panoramic radiographs are an acceptable diagnostic tool for the evaluation of apical lesions in epidemiological studies of dental care (Ahlqwist et al., 1986; Molander et al., 1993).

The high levels of inter- and intra-observer agreement achieved in the present study were probably due to the calibration of examiners before the study and the use of strict criteria in the examination of radiographs. All radiographs evaluated in this investigation were judged to be of high quality and were examined under optimal light conditions with magnification. Several authors have supported the use of magnification and ideal light conditions in radiographic interpretation to enable better visualization of detailed radiographic information (Arnold, 1987; Patel et al., 2000).

Similar to previous epidemiological studies (De Moor et al., 2000; Georgopoulou et al., 2005; Lupi-Pegurier et al., 2002), this study examined an average of 25 teeth per subject. This high number may be due to the tendency for patients to retain their natural teeth longer or to selection bias, as more than half (51%) of examined teeth belonged to young patients (17–34 years old). Such a young population sample might also have influenced the results of this investigation, as AP and root canal fillings are more common in elderly patients. Overall, 10.3% of teeth were missing, although we did not gather information about the reasons for tooth loss. The extent to which the number of missing teeth might affect the prevalence of AP or root-filled teeth is unknown.

The present study found that 13.2% of teeth were endodontically treated, which falls within the range reported by comparable studies (2.0–22.8%; Table 1). Most root-filled teeth were mandibular and maxillary first molars. As the first permanent teeth to erupt, these molars are more prone to caries, operative procedures, and pulpal disease, and consequently are subjected more often to endodontic treatment.

The overall prevalence of AP (15.1%) was higher than those reported in other studies, but was close to the incidence reported in Greek (13.6%) and Belarusian (12%) populations (Table 2). Given that a mean of 25 teeth were examined per subject, the likelihood of detecting a apical lesion in an average patient was high. The incidence of AP in non-filled teeth was 8.3%, suggesting a considerable need for primary endodontic treatment in this population.

All previous epidemiological studies showed a much higher percentage of AP associated with root-filled teeth in comparison with non-root-filled teeth. In our study, 59.5% of root-filled teeth had apical pathology, which fell within the range reported by other studies (16.8–61%; Table 1). We found filled roots and AP in more maxillary than mandibular teeth, confirming the findings of several other investigators (Buckley and Spangberg, 1995; Georgopoulou et al., 2005; Lupi-Pegurier et al., 2002). Apical lesions were associated more frequently with maxillary first premolars and mandibular first molars, reflecting the complex anatomy of these teeth, which may explain the failure of root canal treatment. However, the presence of AP in association with a root-filled tooth does not necessarily indicate such treatment failure. Apical radiolucency scored as treatment failure may in fact represent a healing apical lesion (Ørstavik, 1996). For this reason, care should be taken when using radiographs as the sole method for evaluating the success or failure of endodontic treatment. In the absence of other clinical information, the diagnostic value of this method is limited. On the other hand, the incidence of AP may be underestimated because apical lesions with <30% loss of the mineral component of bone are often not detectable radiographically. In other words, cortical bone must be affected to induce radiographic change (Bender, 1982). At this point, it is important to emphasize that the results of our study, might have been affected by the dynamic nature of the periapical lesion whether occurrence or healing.

Endodontic success is founded on three basic principles: mechanical instrumentation, disinfection, and complete filling of the instrumented root canal(s) with a biocompatible material (Kerekes and Tronstad, 1979). Only the last parameter can be scored partially on radiographs (Weiger et al., 1997). In the current study, evaluation of the technical quality of root canal treatment on the basis of root canal filling length revealed that 74.5% of root fillings were executed inadequately (Table 5). These results were worse than those of most other published studies, which showed unacceptable root filling in about 53–69% of cases (De Moor et al., 2000; Loftus et al., 2005; Lupi-Pegurier et al., 2002; Segura-Egea et al., 2004). Although these studies used different parameters to evaluate endodontic treatment, all found that the majority of root canal fillings were executed poorly. These findings suggest that the technical quality of endodontic treatment, which is a major factor in the healing and prevention of apical pathosis, is generally inadequate (Ödesjö et al., 1990; Sjogren et al., 1990). In Palestine, general practitioners provide most endodontic treatment, which is considered to be of low quality due to the lack of rubber dam use, inadequate aseptic techniques, and poor root canal cleaning and shaping. All of these factors contribute to the introduction or persistence of microbes and their metabolic products within root canal systems, which results in the development of periradicular disease (Nair et al., 1990a,b; Saunders et al., 1997).

The results of the present study are consistent with those of previous studies (Boucher et al., 2002; De Moor et al., 2000; Loftus et al., 2005; Lupi-Pegurier et al., 2002; Segura-Egea et al., 2004) and indicate a strong correlation between the technical quality of root canal treatment and apical health. We found that only 25.5% of root fillings were of adequate length, but only 7.3% of these were associated with AP. Significantly more apical lesions were associated with inadequate root canal fillings (>2 mm from the radiographic apex, extruding from the apex, or present only in the pulp chamber). Root fillings of inadequate length risk the development of AP due to remnants of dentin or infected pulp in the apical part of the root canal, as observed in 77.2% of short fillings in our study. In a retrospective study examining the influence of apical instrumentation on treatment outcomes, Sjogren et al. (1990) showed that adequate root canal fillings (within 2 mm of the radiographic apex) were associated with lower incidence of AP and better success rate when compared to root canal filling limited to the pulp chamber or extruding from the radiographic apex. A recent meta-analysis of studies investigating optimal obturation length found that fillings extruding beyond the radiographic apex were correlated with an increased incidence of apical pathology and poor prognosis (Schaeffer et al., 2005). The overfilling of a root canal may cause tissue damage due to over-instrumentation and an inflammatory reaction due to the extrusion of filling material or infected debris into the apical area. Moreover, root canal filling materials can induce a foreign body reaction leading to the development of apical lesions, even in the absence of bacterial involvement (Nair et al., 1990a,b).

5. Conclusion

This study provides epidemiological data about AP and the technical quality of root canal treatment in Palestine. The results indicate a high prevalence of AP and a very high frequency of poorly executed root canal treatments compared with similar studies conducted in other countries. The incidence of AP was higher in root-filled than in untreated teeth, demonstrating a strong correlation between the quality of root canal filling and the prevalence of AP.

These findings indicate the great need for improvement of endodontic treatment in Palestine through emphasis on undergraduate endodontic teaching, more training of general practitioners and the great need for endodontic specialists.

Footnotes

Peer review under responsibility of King Saud University.

graphic file with name fx1.jpg

Open in a new tab

References

  1. Ahlqwist M., Halling A., Hollender L. Rotational panoramic radiography in epidemiological studies of dental health. Swedish Dental Journal. 1986;10:79–84. [PubMed] [Google Scholar]
  2. Andreasen J.O., Rud J. Correlation between histology and radiography in the assessment of healing after endodontic surgery. International Journal of Oral Surgery. 1972;1:161–173. doi: 10.1016/s0300-9785(72)80006-1. [DOI] [PubMed] [Google Scholar]
  3. Arnold L.V. The radiographic detection of initial carious lesions on the proximal surfaces of teeth. Part II. The influence of viewing conditions. Oral Surgery, Oral Medicine, and Oral Pathology. 1987;64:232–240. doi: 10.1016/0030-4220(87)90096-x. [DOI] [PubMed] [Google Scholar]
  4. Barbat J., Messer H.H. Detectability of artificial periapical lesions using direct digital and conventional radiography. Journal of Endodontics. 1998;24:837–842. doi: 10.1016/S0099-2399(98)80014-9. [DOI] [PubMed] [Google Scholar]
  5. Bender I.B. Factors influencing the radiographic appearance of bony lesions. Journal of Endodontics. 1982;8:161–170. doi: 10.1016/S0099-2399(82)80212-4. [DOI] [PubMed] [Google Scholar]
  6. Boucher Y., Matossian L., Rilliard F., Machtou P. Radiographic evaluation of the prevalence and technical quality of root canal treatment in a French subpopulation. International Endodontic Journal. 2002;35:229–238. doi: 10.1046/j.1365-2591.2002.00469.x. [DOI] [PubMed] [Google Scholar]
  7. Buckley M., Spangberg L.S.W. The prevalence and technical quality of endodontic treatment in an American subpopulation. Oral Surgery, Oral Medicine and Oral Pathology. 1995;79:92–100. doi: 10.1016/s1079-2104(05)80081-2. [DOI] [PubMed] [Google Scholar]
  8. De Cleen M.J., Schuurs A.H., Wesselink P.R., Wu M.K. Periapical status and prevalence of endodontic treatment in an adult Dutch population. International Endodontic Journal. 1993;26:112–119. doi: 10.1111/j.1365-2591.1993.tb00552.x. [DOI] [PubMed] [Google Scholar]
  9. De Moor R.J., Hommez G.M., De Boever J.G., Delme K.I., Martens G.E.I. Periapical health related to the quality of root canal treatment in a Belgian population. International Endodontic Journal. 2000;33:113–120. doi: 10.1046/j.1365-2591.2000.00295.x. [DOI] [PubMed] [Google Scholar]
  10. Eriksen H.M., Berset G.P., Hansen B.F., Bjertness E. Changes in endodontic status 1973–1993 among 35-year-olds in Oslo, Norway. International Endodontic Journal. 1995;28:129–132. doi: 10.1111/j.1365-2591.1995.tb00286.x. [DOI] [PubMed] [Google Scholar]
  11. Eriksen H.M., Bjertness E. Prevalence of apical periodontitis and results of endodontic treatment in middle-aged adults in Norway. Endodontics and DentalTraumatology. 1991;7:1–4. doi: 10.1111/j.1600-9657.1991.tb00174.x. [DOI] [PubMed] [Google Scholar]
  12. Frisk F., Hugoson A., Hakeberg M. Technical quality of root fillings and periapical status in root filled teeth in Jönköping, Sweden. International Endodontic Journal. 2008;41(11):958–968. doi: 10.1111/j.1365-2591.2008.01457.x. [DOI] [PubMed] [Google Scholar]
  13. Georgopoulou M.K., Spanaki-Voreadi A.P., Pantazis N., Kontakiotis E.G. Frequency and distribution of root filled teeth and apical periodontitis in a Greek population. International Endodontic Journal. 2005;38:105–111. doi: 10.1111/j.1365-2591.2004.00907.x. [DOI] [PubMed] [Google Scholar]
  14. Jiménez-Pinzón A., Segura-Egea J.J., Poyato-Ferrera M., Velasco- Ortega E., Rıós-Santos J.V. Prevalence of apical periodontitis and frequency of root-filled teeth in an adult Spanish population. International Endodontic Journal. 2004;37:167–173. doi: 10.1111/j.0143-2885.2004.00759.x. [DOI] [PubMed] [Google Scholar]
  15. Kabak Y., Abbott P.V. Prevalence of apical periodontitis and quality of endodontic treatment in an adult Belarusian population. International Endodontic Journal. 2005;38:238–245. doi: 10.1111/j.1365-2591.2005.00942.x. [DOI] [PubMed] [Google Scholar]
  16. Kakehashi S., Stanley H.R., Fitzgerald R.J. The effects of surgical exposures of dental pulps in germ-free and conventional laboratory rats. Oral Surgery, Oral Medicine, and Oral Pathology. 1965;20:340–349. doi: 10.1016/0030-4220(65)90166-0. [DOI] [PubMed] [Google Scholar]
  17. Kerekes K., Tronstad L. Long term results of endodontic treatment performed with standardized technique. Journal of Endodontics. 1979;5:83–90. doi: 10.1016/S0099-2399(79)80154-5. [DOI] [PubMed] [Google Scholar]
  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. International Endodontic Journal. 2001;34:198–205. doi: 10.1046/j.1365-2591.2001.00370.x. [DOI] [PubMed] [Google Scholar]
  19. Lee S., Messer H. Radiographic appearance of artificially prepared periapical lesions confined to cancellous bone. International Endodontic Journal. 1988;19:64–72. [Google Scholar]
  20. Loftus J.J., Keating A.P., McCartan B.E. Periapical status and quality of endodontic treatment in an adult Irish population. International Endodontic Journal. 2005;38:81–86. doi: 10.1111/j.1365-2591.2004.00902.x. [DOI] [PubMed] [Google Scholar]
  21. Lupi-Pegurier L., Bertrand M.F., Muller-Bolla M., Rocca J.P., Bolla M. Periapical status, prevalence and quality of endodontic treatment in an adult French population. International Endodontic Journal. 2002;35:690–697. doi: 10.1046/j.1365-2591.2002.00547.x. [DOI] [PubMed] [Google Scholar]
  22. Marques M.D., Moreira B., Eriksen H.M. Prevalence of apical periodontitis and results of endodontic treatment in an adult Portuguese population. International Endodontic Journal. 1998;31:161–165. doi: 10.1046/j.1365-2591.1998.00136.x. [DOI] [PubMed] [Google Scholar]
  23. Molander B., Ahlqwist M., Grondahl H.G., Hollender L. Comparison of panoramic and intraoral radiography for the diagnosis of caries and periapical pathology. Dentomaxillofacial Radiology. 1993;22:28–32. doi: 10.1259/dmfr.22.1.8508938. [DOI] [PubMed] [Google Scholar]
  24. Muhammed A.H., Manson-Hing L.R. A comparison of panoramic and intraoral radiographic surveys in evaluating adental clinic population. Oral Surgery, Oral Medicine and Oral Pathology. 1982;54:108–117. doi: 10.1016/0030-4220(82)90425-x. [DOI] [PubMed] [Google Scholar]
  25. Nair P.N.R., Sjogren U., Krey G., Sundqvist G. Therapy-resistant foreign body giant cell granuloma at the periapex of a root-filled human tooth. Journal of Endodontics. 1990;16:589–595. doi: 10.1016/S0099-2399(07)80202-0. [DOI] [PubMed] [Google Scholar]
  26. Nair P., Sjogren U., Krey G., Kahnberg K., Sundqvist G. Intraradicular bacteria and fungi in root-filled, asymptomatic human teeth with therapy-resistant periapical lesions: a long term light and electron microscope follow-up study. Journal of Endodontology. 1990;16:580–588. doi: 10.1016/S0099-2399(07)80201-9. [DOI] [PubMed] [Google Scholar]
  27. Ödesjö B., Helldén L., Salonen L., Langeland K. Prevalence of previous endodontic treatment, technical standard and occurrence of periapical lesions in a randomly selected adult, general population. Endodontics and Dental Traumatology. 1990;6:265–272. doi: 10.1111/j.1600-9657.1990.tb00430.x. [DOI] [PubMed] [Google Scholar]
  28. Ørstavik D. Time-course and risk analyses of the development and healing of chronic apical periodontitis in man. International Endodontic Journal. 1996;29:150–155. doi: 10.1111/j.1365-2591.1996.tb01361.x. [DOI] [PubMed] [Google Scholar]
  29. Patel N., Rushton V.E., Macfarlane T.V., Horner K. The influence of viewing conditions on radiological diagnosis of periapical inflammation. British Dental Journal. 2000;189:40–42. doi: 10.1038/sj.bdj.4800596. [DOI] [PubMed] [Google Scholar]
  30. Petersson K., Lewin B., Ha kansson J., Olsson B., Wennberg A. Endodontic status and suggested treatment in a population requiring substantial dental care. Endodontics and Dental Traumatology. 1989;5:153–158. doi: 10.1111/j.1600-9657.1989.tb00352.x. [DOI] [PubMed] [Google Scholar]
  31. Saunders W.P., Saunders E.M., Sadiq J., Cruickshank E. Technical standard of root canal treatment in an adult Scottish sub-population. British Dental Journal. 1997;182:382–386. doi: 10.1038/sj.bdj.4809394. [DOI] [PubMed] [Google Scholar]
  32. Schaeffer M.A., White R.R., Walton R.E. Determining the optimal obturation length: a meta-analysis of literature. Journal of Endodontics. 2005;31:271–274. doi: 10.1097/01.don.0000140585.52178.78. [DOI] [PubMed] [Google Scholar]
  33. Segura-Egea J.J., Jiménez-Pinzoón A., Poyato-Ferrera M., Velasco-Ortega E., Rís-Santos J.V. Periapical status and quality of root fillings and coronal restorations in an adult Spanish population. International Endodontic Journal. 2004;37:525–530. doi: 10.1111/j.1365-2591.2004.00826.x. [DOI] [PubMed] [Google Scholar]
  34. Sidaravicius B., Aleksejuniene J., Eriksen H.M. Endodontic treatment and prevalence of apical periodontitis in an adult population of Vilnius, Lithuania. Endodontics and Dental Traumatology. 1999;15:210–215. doi: 10.1111/j.1600-9657.1999.tb00776.x. [DOI] [PubMed] [Google Scholar]
  35. Sjogren U., HaÈgglund B., Sundqvist G., Wing K. Factors affecting the long-term results of endodontic treatment. Journal of Endodontics. 1990;16:498–504. doi: 10.1016/S0099-2399(07)80180-4. [DOI] [PubMed] [Google Scholar]
  36. Soikkonen K.T. Endodontically treated teeth and periapical findings in the elderly. International Endodontic Journal. 1995;28:200–203. doi: 10.1111/j.1365-2591.1995.tb00300.x. [DOI] [PubMed] [Google Scholar]
  37. Sunay H., Tanalp J., Dikbas I., Bayirli G. Cross-sectional evaluation of the periapical status and quality of root canal treatment in a selected population of urban Turkish adults. International Endodontic Journal. 2007;40:139–145. doi: 10.1111/j.1365-2591.2007.01217.x. [DOI] [PubMed] [Google Scholar]
  38. Sundqvist G. Associations between microbial species in dental root canal infections. Oral Microbiology and Immunology. 1992;7:257–262. doi: 10.1111/j.1399-302x.1992.tb00584.x. [DOI] [PubMed] [Google Scholar]
  39. Touré B., Kane A.W., Sarr M., Ngom C.T.H., Boucher Y. Prevalence and technical quality of root fillings in Dakar, Senegal. International Endodontic Journal. 2008;41:41–49. doi: 10.1111/j.1365-2591.2007.01305.x. [DOI] [PubMed] [Google Scholar]
  40. Weiger R., Hitzler S., Hermle G., Löst C. Periapical status, quality of root canal fillings and estimated endodontic treatment needs in an urban German population. Endodontics and Dental Traumatology. 1997;13:69–74. doi: 10.1111/j.1600-9657.1997.tb00013.x. [DOI] [PubMed] [Google Scholar]

Articles from The Saudi Dental Journal are provided here courtesy of Elsevier

RESOURCES