Incidence, Frequency, and Prevalence

Study
Country
Radiograph
Sample
PrevalenceRF (%)
PrevalenceAP (%)
FrequencyAP total (%)
FrequencyAP RF (%)
Bergenholtz et al. [34]
Sweden
Apical/FMR
Patient
57
6.1
30.5
 
Boltacz-Rzepkowska [35]
Poland
Apical/FMR
Patient
25
     
Boucher et al. [36]
France
Apical/FMR
Patient
62
7.4
29.7
 
Buckley and Spångberg [37]
USA
Apical/FMR
Patient
4.1
31.3
   
Chen et al. [38]
USA
Panoramic
Population
38.8
45.6
5.1
35.5
Da Silva et al. [39]
Australia
Panoramic
Patient
21.4
     
De Cleen et al. [40]
Netherlands
Panoramic
Patient
44.6
6.0
39.2
 
De Moor et al. [41]
Belgium
Panoramic
Patient
63.1
6.6
40.4
 
Dugas et al. [42]
Canada
Apical/FMR
Patient
34.3
3.1
45.4
 
Dutta et al. [6]
Scotland
CBCT
Patient
39.2
5.8
47.4
 
Eckerbom et al. [43]
Sweden
Apical/FMR
Patient
83.5
63
5.2
26.4
Eriksen and Bjertness [45]
Norway
Apical/FMR
Population
56
3.5
36.5
 
Eriksen et al. [46]
Norway
Apical/FMR
Population
24
14
0.6
38.1
Estrela et al. [47]
Brazil
Apical/FMR
Patient
38
     
Georgopoulou et al. [48]
Greece
Apical/FMR
Patient
65.6
85.5
13.6
60
Gulsahi et al. [49]
Turkey
Panoramic
Patient
23.8
1.4
18.2
 
Hollanda et al. [50]
Brazil
Panoramic
Patient
21.4
     
Hommez et al. [51]
Belgium
Apical/FMR
Patient
32.5
     
Huumonen et al. [52]
Finland
Panoramic
Population
61
     
Ilić et al. [53]
Serbia
Panoramic
Patient
85
93.8
51.8
 
Jersa and Kundzina [54]
Latvia
Panoramic
Patient
87
72
7
31
Jimenez-Pinzon et al. [55]
Spain
Apical/FMR
Patient
40.6
61.1
4.2
64.5
Kabak and Abbott [56]
Belarus
Panoramic
Patient
80
12
45
 
Kalender et al. [57]
Cyprus
Panoramic
Patient
64
68
7
62
Kamberi et al. [58]
Kosovo
Panoramic
Patient
12.3
46.3
   
Kirkevang et al. [59]
Denmark
Apical/FMR
Population
52
42.3
3.4
52.2
Kim [60]
South Korea
Panoramic
Patient
22.8
     
Loftus et al. [61]
Ireland
Panoramic
Patient
31.8
33.1
2.0
25.0
Lupi-Pegurier et al. [62]
France
Panoramic
Patient
7.3
31.5
   
Marques et al. [63]
Portugal
Panoramic
Population
22
26
2
21.7
Matijevic et al. [64]
Croatia
Panoramic
Patient
75.9
8.5
   
Moreno et al. [65]
Colombia
Apical/FMR
Patient
49
     
Paes da Silva et al. [5]
Brazil
CBCT
Patient
51.4
3.4
35.4
 
Peciuliene et al. [66]
Lithuania
Apical/FMR
Patient
43.1
     
Persic et al. [67]
Croatia/Austria
Panoramic
Patient
47.3/62.1
     
Peters et al. [68]
Netherlands
Panoramic
Patient
2.5
24.1
   
Petersson et al. [69]
Sweden
Apical/FMR
Patient
93
77
8.7
26.5
Saunders et al. [71]
Scotland
Apical/FMR
Patient
54
67.7
4.9
58.1
Sunay et al. [72]
Turkey
Panoramic
Patient
47
4.2
53.5
 
Skudutyte-Rysstad et al. [73]
Norway
Apical/FMR
Population
23
16
1.1
43
Sidaravicius et al. [74]
Lithuania
Apical/FMR
Population
72
70
7.2
35
Tavares et al. [12]
France
Apical/FMR
Patient
33
     
Touré et al. [75]
Senegal
Apical/FMR
Patient
35.5
59.6
4.6
56.1 (roots)
Tercas et al. [76]
Brazil
Apical/FMR
Patient
67.5
5.9
42.5
 
Tolias et al. [77]
Greece
Panoramic
Population
62.3
     
Tsuneishi et al. [78]
Japan
Apical/FMR
Patient
86.5
69.8
40
 
Weiger et al. [79]
Germany
Panoramic/Apical
Patient
3.0
61
   
Ödesjö et al. [80]
Sweden
Apical/FMR
Population
43.2
2.9
24.5
 
Özbaş et al. [81]
Turkey
Apical/FMR
Patient
1.6
38
   

2.3.2 Longitudinal Studies

These studies follow a number of subjects over a period of time. A synonymous term is cohort study. In the context of population surveys, no intervention is done—all subjects go about their ordinary life and treatments as usual. The condition to be studied needs to be frequent enough in order to provide a sufficient number of cases to be compared with non-cases. A “case” is an individual, or a tooth, with the condition under study, for example apical periodontitis. Also, the length of time between baseline and follow-up needs to be adjusted in relation to what is intended to be investigated. It needs to be long enough for the event under study to take place and short enough to be registered before the event is impossible to identify. Apical periodontitis is prevalent enough to produce a sufficient number of cases. However, a healthy tooth may develop apical periodontitis and be root canal treated and even extracted between baseline and follow-up if the time span is too long. Under such circumstances a lot of information is lost and should warrant shorter follow-up periods.
Longitudinal studies measuring the incidence of apical periodontitis are scarce. They are expensive to conduct and difficult to manage. A major problem is loss to follow-up. If too many participants are prevented from participating, or choose not to, it should be questioned as to whether the remaining sample is representative for the population.

2.3.3 Methodology

2.3.3.1 Selection

When reviewing studies in the field of endodontic epidemiology, it is apparent that the most common individual studied is the one who seek dental care at a dental school and have been examined with full-mouth radiographs and/or panoramic x-rays. This is a convenient approach since researchers do not have to make an effort to invite individuals to the examination. Also, if individuals examined are exposed to radiation in the context of seeking dental care, there will be a lesser ethical dilemma as to whether the radiological examination was justified or not. However, it is reasonable to assume that individuals seeking dental care are not representative for the whole population. This assumption may be especially true for patients seeking dental care at a dental school. These patients may have more extensive treatment needs and may have smaller financial resources than the population as a whole. Thus, in order to render samples representative for the population, researchers should consider other approaches such as studying a randomized sample of individuals. If large enough, the randomized sample may be regarded as representative for the population from which it was sampled. Studies using randomized samples are in minority in endodontic epidemiology. Despite the methodological considerations discussed, the number of studies using convenience sampling is still in majority.

2.3.3.2 Radiographic Examination

Does the periapical destruction always represent apical periodontitis ? In a clinical context non-root-filled teeth with a periapical destruction may be examined with regard to pulpal sensitivity to confirm the diagnosis. In an epidemiological study exclusively based on radiographs, this information is lacking but it is usually considered uncontroversial since the most probable diagnosis is apical periodontitis [3]. Older studies investigating root-filled teeth and apical periodontitis, more often than today, used apical radiographs. During recent decades panoramic radiographs have emerged as a simpler and more economical technique. Also, and more important, it exposes the individual with a lower radiation dose compared to a full mouth examination using apical radiographs. In the context of epidemiological studies, the panoramic radiograph has been demonstrated as reasonably effective as the apical radiograph when apical periodontitis is studied [4]. It performs worse than the apical radiograph when root filling quality is studied. Cone beam CT (CBCT) is a rather new technique which has shown to be promising as an adjunct in endodontic diagnostics. However, it has not been used in endodontic epidemiology other than in a few studies [5, 6]. It may be viewed as doubtful if it is justifiable to expose healthy individuals with a much larger radiation dose (compared to a full mouth examination) when studying the prevalence and frequency of apical periodontitis. Apical periodontitis is a prevalent condition and not life-threatening other than for selected patients. It may thus be argued that CBCT is not suited for screening. Others claim that it is justifiable and advocate the use of CBCT in epidemiological studies, highlighting the drawbacks with two-dimensional techniques [5].
It is acknowledged that when studying apical periodontitis or root filling quality, researchers have to consider a variation both between observers and also within observers over time [7]. This is often referred to as inter- and intraobserver variation, respectively. In order to cope with the problem, two different strategies have been developed to reduce observer variation when studying apical periodontitis.
Reit and Gröndahl [8] suggested that observer variation may be reduced if the number of false-positive findings is kept to a minimum by instructing the observers to only register a periapical destruction when certain, introducing a five-scale index where score 1 = “periapical destruction of bone definitely not present” and 5 = “periapical destruction of bone definitely present.” This index is also called the PRI-index (probability index). Reit [9] found that calibration of observers had only limited benefits in reducing observer variation.
Örstavik et al. [10] presented the periapical index (PAI) . In contrast to Reit [9] it is proposed that observers should be calibrated, and in contrast to Reit and Gröndahl [8] there is no overall strategy to reduce false-positive findings. PAI works as follows: observers are presented with a five-graded scale with radiographs with different periapical expressions ranging from periapical health (score 1) to an aggravating periapical condition (score 2–5) (Fig. 2.1). The periapical expressions on the radiographs have been validated with the histological periapical expression in a previous study using biopsies from an autopsy material [3]. For the purpose of calibration of observers to PAI, observers are instructed to use the scale when observing 100 radiographs. When in doubt, observers are instructed to assign a higher score. The reason for this is findings from Brynolf [3] where the histological periapical expression always was more severe than the radiological periapical expression. The registrations are then compared to a “golden standard” constructed by a panel of observers who have assigned “true” scores to all 100 teeth. If the observer variation is low enough compared to the “golden standard,” observers may use PAI in their study.

A332473_1_En_2_Fig1_HTML.gif
Fig. 2.1

PAI-Reference scale with scores 1–5 and corresponding radiological and histological periapical expressions [10]
An alternative to PAI, when defining a healthy and diseased periapex, modified Strindberg criteria may be used [7, 11]. There is only a text reference to describe the periapical expression (Table 2.2).

Table 2.2

Text reference for the periapical expression according to modified Strindberg criteria as adopted by Reit and Hollender [7]
0 = Normal periapical condition
1 = Increased width of the periodontal membrane space. Lamina dura continuous
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Oct 24, 2018 | Posted by in Periodontics | Comments Off on Incidence, Frequency, and Prevalence
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