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Figure 3.1 Age distribution of 948 South African patients with radicular cysts.
Figure 3.2 Age distribution of 1970 patients with radicular cysts from Sheffield, England, 1990–2004 (n = 1970).
Source: Based on Jones et al. (2006 ).
Residual cysts are very unusual in the first, second, or third decades and peak at a slightly older age, usually in the fifth decade. Lo Muzio et al. (2017 ) found a mean age of 49.4 years (n = 218; range: 17–90) and, in their large Greek series, Tamiolakis et al. (2019 ) found a mean age of 50.5 years (n = 749; range 11–93) for residual cysts.
Box 3.1 Radicular Cyst: Epidemiology – Key Facts
Radicular cysts are the most common cystic lesion of the jaws
They comprise about 60% of all odontogenic cysts
Residual cysts account for 10–20% of radicular cysts
Overall radicular cysts are the most common cause of bony swellings
They are slightly more common in males (M : F = 1.4 : 1)
Peak age is the third and fourth decades (20–40 years)
Rare in children
Very rare on deciduous teeth
Sex
Almost all studies show that all odontogenic cysts are slightly more common in males than in females (Table 1.3). With regard to radicular cysts in the South African series, 555 (58.5%) were in males and 393 (41.5%) in females (M : F 1.41 : 1), a statistically significant difference (P < 0.002). In the Sheffield study, 1914 (51.5%) were in males and 1801 (48.5%) in females (M : F 1.06 : 1; Jones et al. 2006 ), but this difference was not significant.
Site
Figure 3.3 shows that radicular cysts may arise at any site in the jaws, but are more common in the maxilla (60%) than the mandible, with a particularly high frequency in the anterior maxilla, with about 40–50% of all cases occurring in this region. There are a number of possible reasons for this. First, in addition to the hazard posed by dental caries, maxillary incisors have in the past, perhaps more frequently than other teeth, had silicate restorations placed in them, with consequent high risk to their pulps. If this were the cause, then the prevalence of cysts at this site might reduce in future generations. Second, there is a high prevalence of palatal invaginations in the maxillary lateral incisors and a high frequency in which pulp death supervenes in these teeth. Third, maxillary anterior teeth are probably more prone than others to traumatic injuries, which may lead to pulp death.
Figure 3.3 Site distribution of radicular cysts. A comparison of 1111 cases from South Africa (Johannesburg) and 1974 cases from England (Sheffield).
Recent studies, however, show that this site distribution is seen across the world and has not changed in the last two decades, suggesting that trauma and susceptibility to caries may be the main reasons. The proportion of radicular cysts associated with the maxillary incisors has been reported to be 54.4% in India (Ramachandra et al. 2011 ), 52.8% in England (Jones et al. 2006 ), 47.8% in Turkey (Soluk Tekkeşin et al. 2012b ), 37.3% in Iran (Sharifian and Khalili 2011 ), 36.4% in Sicily (Tortorici et al. 2008), and 43% in Brazil (Tavares et al. 2017 ). Most studies agree that the mandibular molar area is the next most common site.
Clinical Presentation
Radicular Cyst
An essential criterion for the diagnosis of a radicular cyst is that it is always associated with a tooth with a non‐vital pulp, usually as a result of dental caries.
Many radicular cysts are small and symptomless and are discovered by chance during radiological examination of caries or non‐vital teeth. Overall, however, radicular cysts are probably the most common cause of swelling of the jaws and a slowly enlarging swelling is a common presenting complaint. At first the enlargement is bony hard, but as the cyst increases in size, the cortical plate is resorbed and only a thin layer of subperiosteal new bone covers the lesion. The swelling then exhibits ‘springiness’ or ‘egg‐shell crackling’. Only when the cyst has completely eroded the bone, often due to secondary infection, will the lesion be fluctuant. In the maxilla there may be buccal or palatal enlargement, whereas in the mandible it is usually labial or buccal and only rarely lingual.
Radicular cysts may occasionally be associated with pain, but this is usually pulpal in origin, or is due to secondary infection, when there may be a sinus leading from the cyst cavity to the oral mucosa. However, even infected lesions may be symptomless. In a histological examination of 25 radicular cysts, Vier and Figueiredo (2002 ) showed that 21 contained abscess cavities that disrupted the epithelial lining. This suggests that although secondary infection may be quite common, it is not often a cause of pain. Conversely, some patients complain of pain, although no evidence of infection is found clinically and no evidence of acute inflammation is seen histologically after the cyst has been removed.
Quite often, a patient may have multiple radicular cysts. Usually this is clearly associated with dental caries in multiple teeth, but the fact remains that radicular cysts are relatively rare in relation to the vast numbers of grossly carious teeth with dead pulps. This has led a number of authors to believe that there are cyst‐prone individuals who show a particular susceptibility to developing radicular cysts (Oehlers 1970 ). It is possible that in most people periapical infections are suppressed and cyst formation is inhibited, but that cyst‐prone subjects have a defective immunological surveillance and suppression mechanism. Multiple radicular cysts may also be seen in patients with hereditary dental defects (e.g. multiple dens‐in‐dente or dentinogenesis imperfecta), but in these cases this is because of morphological defects resulting in increased caries or early exposure and death of the pulp.
Radicular cysts arising from deciduous teeth appear to be very rare. Shear found that of 1300 radicular cysts recorded in his department at the University of the Witwatersrand over a 25‐year period, only 7 were associated with deciduous teeth (0.5%). In an extensive review of the literature from 1898 to 1985, only 28 cases were found (Lustmann and Shear 1985 ). Subsequent reviews have recorded 112 cases up to 2004 (Nagata et al. 2008 ) and a total of 122 up to 2010 (Shetty et al. 2010 ).
The frequency is probably higher than these figures would suggest, because many lesions may not be diagnosed before the deciduous teeth are extracted or exfoliate, and lesions may not be submitted for histological examination. Nevertheless, the frequency is substantially lower than of radicular cysts associated with permanent teeth
