None of these cysts appeared in the first (1972) edition of the WHO classification of odontogenic tumours and cysts, but they were included in the second edition (Kramer et al. 1992 ). The 1992 WHO classification used the term paradental cyst, but included inflammatory collateral cyst and mandibular infected buccal cyst as synonyms. The classification did however make a distinction between cysts arising in association with third molars and a distinctive variant arising on the buccal aspect of first molars in children.
In a review of the world literature, Philipsen et al. (2004 ) concurred with this view, but found that the literature included at least 16 names for these cysts, including marginal wisdom tooth cyst (Hofrath 1930 ), inflammatory collateral cyst (Main 1970 ), paradental cyst (Craig 1976 ), mandibular infected buccal cyst (Stoneman and Worth 1983 ), and mandibular buccal bifurcation cyst (Pompura et al. 1997 ). Slater (2003 ) had suggested eruption pocket cyst, which nicely describes the association with an erupting tooth as well the morphological feature of a pocket cyst. Nevertheless, this name was never used again in the literature. Philipsen et al. (2004 ) preferred to use the term inflammatory paradental cyst to encompass all the collateral cysts of inflammatory origin. They pointed out, however, that differences in clinical presentation and appearance justify separating the cyst into clinicopathological variants. In the literature up to 2004 they identified reports of 342 patients with 377 cysts. The most common lesions, representing 61.4% of cysts, arose in adults and were associated with a mandibular third molar. The second group, comprising 35.9% of cysts, were related to the first and second molars and arose in younger individuals with a characteristic clinical presentation. A further 10 cysts (2.7%) were described as occurring in the gobulomaxillary region between the second incisor and canine. Eight of these ten cases were reported by Vedtofte and Holmstrup (1989 ). There are also reports of four cysts arising in association with mandibular premolars (Morimoto et al. 2004 ) and one case arising on a maxillary second molar (Vedtofte and Praetorius 1989 ).
It is apparent from this discussion that all these terms refer to a similar lesion and have been used synonymously to describe an inflammatory collateral cyst that arises towards the buccal aspect of a partially, or recently, erupted tooth. It is also clear that the vast majority of cysts (about 97%) fall into two main groups – those associated with third molars and those associated with first or second molars. In the previous edition of this book we suggested that these two variants should be called paradental cyst, using the criteria of Craig (1976 ), for lesions associated with third molars and juvenile paradental cyst for lesions in younger individuals associated with mandibular first or second molars. Subsequently, however, the 2017 WHO classification (Speight and Soluk Tekkeşin 2017 ) adopted the term inflammatory collateral cysts for all cysts found towards the buccal aspect of the roots of partially or recently erupted teeth, and described the two main types as paradental cyst and mandibular buccal bifurcation cyst. This terminology has been retained in the latest edition of the WHO classification (WHO 2022a ; Speight and Soluk Tekkeşin 2022b ).
Although the paradental cyst is usually defined as arising on mandibular third molars, identical lesions have occasionally been described on second permanent molars when the third molar is absent and the second molar is the last standing tooth (Vedtofte and Praetorius 1989 ; Maruyama et al. 2015 ). Thus the definition of the paradental cyst might more appropriately refer to the ‘last standing mandibular molar tooth’. The vast majority, however, are located on third molars. The key features of the two main variants are summarised in Box 4.1 and later Tables 4.2 and 4.3.
Clinical Features
Most descriptions of inflammatory collateral cysts are to be found in single case reports or in small case series. In a review of the world literature, Philipsen et al. (2004 ) found 23 case reports and 18 case series reporting 377 cysts in 342 patients. More recently, Ramos et al. (2012 ) reviewed 16 reports (57 cases) of buccal bifurcation cyst. Selected case series, and the review of Philipsen et al. (2004 ), reporting paradental cysts and mandibular buccal bifurcation cysts are summarised in Tables 4.2 and 4.3, respectively.
Frequency
Table 4.1 summarises the reported frequencies of inflammatory collateral cysts in selected series from a wide geographical distribution. Data are taken from the same references shown in Table 1.3 (Chapter 1) and from the frequencies encountered in the larger series shown in Table 4.2. Almost without exception, the authors of the papers cited in Table 1.3 used ‘paradental cyst’ as a generic term for all inflammatory collateral cysts, so these frequencies include both paradental cysts and mandibular buccal bifurcation cysts.
The frequency ranges from 0 to 13.6% of odontogenic cysts (Table 4.1). Those authors who presented series of paradental cysts found that they comprised between 3.0 and 4.7% of odontogenic cysts encountered in their departments (Craig 1976 ; Ackermann et al. 1987 ; de Sousa et al. 2001 ).
In Shear's large series of 3496 jaw cysts from South Africa (see Table 1.1), there were 109 inflammatory collateral cysts representing 3.1% of all jaw cysts and 3.6% of odontogenic cysts. In Craig's original series (Craig 1976 ), paradental cysts comprised 4.7% of 1051 odontogenic cysts, and in a recent study from the same department (Jones et al. 2006 ), a diagnosis of paradental cyst was made on 402 occasions over a 30‐year period (1975–2004), representing 5.6% of 7121 odontogenic cysts.
Box 4.1 Key Features of the Two Main Clinical Variants of Inflammatory Collateral Cysts
| Paradental cyst | Mandibular buccal bifurcation cyst | |
|---|---|---|
| Site | Mandibular third molar | Mandibular first or second molar |
| % of ICCa | 61% | 36% |
| % of OCb | 4% |
|