ICC, inflammatory collateral cysts; n, total number of odontogenic cysts in each study.
Few studies have determined separately the frequencies of paradental cysts and mandibular buccal bifurcation cysts. Tamiolakis et al. (2019 ) reviewed 5165 odontogenic cysts and found only 57 (1.1%) inflammatory collateral cysts. Of these, 53 were paradental cysts on third molars and only 4 were mandibular buccal bifurcation cysts in children, suggesting frequencies of 1.0% and 0.1%, respectively. Jones et al. (2006 ) used the term paradental cyst to encompass both types of inflammatory collateral cyst, but found only 15 cases in their paediatric population (patients ≤16 years), representing 2.7% of odontogenic cysts in children (n = 553) and only 0.2% of all odontogenic cysts (n = 7121). Paradental cysts in adults comprised 376 cases, representing 5.2% of odontogenic cysts. These data suggest that paradental cysts are about 10–20 times more common than mandibular buccal bifurcation cysts.
Overall, the data from these studies (Table 4.1) suggest that inflammatory collateral cysts represent about 4% of odontogenic cysts. It is probable, however, that they are under‐reported, because many cases received within pathology departments may have insufficient clinical or radiological information to establish the diagnosis and many may have been diagnosed as inflamed dentigerous cysts, pericoronitis, or inflamed follicles. In departments where the diagnosis is made on a regular basis, the paradental cyst appears to be a common lesion. In the series of Colgan et al. (2002 ), paradental cysts comprised 15 of 60 (25%) cystic lesions associated with lower third molars. This was the second most common diagnosis after dentigerous cyst (30%).
In an analysis of pericoronal tissues from extracted third molars, Costa et al. (2014 ) found that 73.5% (83 of 113) showed pathological changes and of these, 55 (66.2%) were diagnosed as paradental cysts and 21 (25.3%) as dentigerous cysts. It should be noted, however, that the majority of lesions were associated with erupted or partially erupted teeth (85.5%), and only seven teeth were unerupted, suggesting that a number of dentigerous cysts were diagnosed in association with partially erupted impacted third molars. Mohammed et al. (2019 ) undertook a similar study and examined 407 tissue specimens associated with impacted teeth from 390 patients. The most common diagnosis was dentigerous cyst (56.5% of lesions; n = 230), followed by odontogenic keratocyst (6.1%) and then paradental cyst (5.7%; n = 23).
It is interesting that these figures contrast starkly with data from other studies that have shown that paradental cysts are exceedingly rare or are not diagnosed at all. Six of the studies shown in Table 4.1 did not record any inflammatory collateral cysts. Costa et al. (2014 ) also reviewed 11 studies that reported histological findings associated with third molars in 8464 patients. The most common finding was of normal dental follicle (76%), but the most common lesions were dentigerous cysts, found in 410 cases (11%). Only one paper (Al‐Khateeb and Bataineb 2006 ) reported finding any paradental cysts and there were only 2, suggesting an overall prevalence of 0.05%. In a systematic review of the prevalence of odontogenic cysts and tumours associated with impacted third molars, Mello et al. (2019 ) reviewed 16 studies reporting histological diagnoses associated with more than 50 000 teeth. There were 1371 cysts, of which 783 (57.1%) were dentigerous cysts, 400 (29.2%) radicular cysts, and 150 (10.9%) odontogenic keratocysts. These authors also found the same single study (Al‐Khateeb and Bataineb 2006 ) that had reported only 2 paradental cysts. These data are similar to other studies that have examined tissues associated with impacted third molars and have not reported a single paradental cyst (e.g. Curran et al. 2002 [USA]; Stathopoulos et al. 2011 [Greece]; Patil et al. 2014 [India]).
Table 4.2 Paradental cysts. Age, sex, and site distribution from selected reports, and from the review of 222 cases by Philipsen et al. (2004 ).
| References | n | Mean agea | Age range | Male (%) | % Bilateral |
|---|---|---|---|---|---|
| Craig (1976 ) | 48 | 3rd decade | NR |
|
