Читать книгу Shear's Cysts of the Oral and Maxillofacial Regions - Paul M. Speight - Страница 65

	Paradental cyst	Mandibular buccal bifurcation cyst
Site	Mandibular third molar	Mandibular first or second molar
% of ICCa	61%	36%
% of OCb	4%	0.2%
Location	Distal or disto‐buccal	Buccal
Proportion in males	70%	55%
Proportion bilateral	4%	25%
Clinical features	History of pericoronitis on a partially erupted tooth. Cyst is continuous with the pericoronal pocket	Swelling, painful. May be signs of infection and suppuration. Tooth tipped buccally, deep pockets in continuity with cyst lumen
Radiology	Well‐demarcated disto‐buccal radiolucency, superimposed over roots. Distal follicular space preserved	Well‐demarcated radiolucency over buccal aspect of roots, buccal expansion with corticated outline

^a Frequency as a proportion of inflammatory collateral cysts.

^b Frequency as a proportion of all odontogenic cysts.

Table 4.1 Selected papers, with a wide geographical distribution, showing the frequency of inflammatory collateral cysts as a proportion of total odontogenic cysts. Based on Philipsen et al. (2004).

	Country	n	ICC (%)
Data from references in Table 1.3
Meningaud et al. (2006 )	France	695	0
Tortorici et al. (2008 )	Italy (Sicily)	1273	0
Ali (2011 )	Kuwait	196	0
Ramachandra et al. (2011 )	India	252	0
Manor et al. (2012 )	Israel	285	0
Bhat et al. (2019 )	India	125	0
Soluk Tekkeşin et al. (2012b )	Turkey	5003	0.2
Daley et al. (1994 )	Canada	6847	0.5
Grossmann et al. (2007 )	Brazil	2812	0.7
Tamiolakis et al. (2019 )	Greece	5165	1.1
Mosqueda‐Taylor et al. (2002 )	Mexico	856	1.4
Aquilanti et al. (2021 )	Italy	2150	1.5
Sharifian and Khalili (2011 )	Iran	1227	1.8
Ochsenius et al. (2007 )	Chile	2944	3.8
Jones et al. (2006 )	UK	7121	5.6
Kammer et al. (2020 )	Brazil	406	13.6
Data from references in Table 4.2
Ackermann et al. (1989)	South Africa	1852	3.0
Craig (1976 )	UK	1051	4.7
De Sousa et al. (2001 )	Brazil	1256	4.3

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	83.0	2.1
Ackermann et al. (1987 )	50	3rd decade	17–62	70.0	6.0
Vedtofte and Praetorius (1989 )	15	24.4	18–34	60.0	0.0
de Sousa et al. (2001 )	54b	3rd decade	13–47	39.0	NR
Colgan et al. (2002 )	15	27.4	18–43	46.6	6.6
Jones et al. (2006 )	376	29.6	17–74	57.3	NR
Philipsen et al. (2004 )	11	29.9	18–46	63.6	18.0
Tamiolakis et al. (2019 )	53	29.3	18–56	52.8	NR
Mohammed et al. (2019 )	23	30.2	11–51	69.5	NR
Philipsen et al. (2004 )	222c	27.6	18–47	70.6	4.1

n, number of patients; NR, not reported.

^a In some reports, the mean age is not given, so the peak decade is included.

^b Includes three cases on first or second molars.

^c Total cases reviewed, n for each parameter varies.

Table 4.3 Mandibular buccal bifurcation cysts. Age, sex, and site distribution from selected reports, and from the review of 110 cases by Philipsen et al. (2004 ) (see text for discussion).

References				First molars	Second molars
	n	% Male	% Bilateral	n	Mean age	Age range	n	Mean age	Age range
Vedtofte and Praetorius (1989 )	12	33.3	16.6	5	8.0	7–9	7	13.3	11–15
Wolf and Hietanen (1990 )	6	16.6	NR	3	7.3	6–9	3	13.0	12–14
Thurnwald et al. (1994 )	10	70.0	40.0	10	7.7	5–9	–	–	–
Pompura et al. (1997 )	32	43.7	37.5	32	7.5	5–11	–	–	–
Philipsen et al. (2004 )	110a	55.2	23.9	36	8.7	5–47	13	17.4	10–40

n = number of patients; NR, not reported.

^a Total cases reviewed, n for each parameter varies.

These data cannot be taken to represent the true prevalence of paradental cysts because many studies were based in surgical units, the criteria for diagnosis are not given, and although most report ‘impacted’ teeth, it is rarely stated whether the tooth is fully unerupted or partially erupted. These studies do, however, suggest that many clinicians may not recognise or diagnose paradental cysts.

There is some evidence that many clinicians and pathologists in the United States may not recognise the paradental cyst as an entity, but rather regard it as a variant of dentigerous cyst. One of the best and most widely used textbooks on oral and maxillofacial pathology (Neville et al. 2016 ) recognises the buccal bifurcation cyst in children, but is uncertain about the paradental cyst. Its authors agree that the features may be due to chronic pericoronitis, but suggest that most are probably diagnosed as examples of inflamed dentigerous cysts. Two other excellent and widely used textbooks take a similar stance and suggest that the paradental cyst is an inflamed dentigerous cyst that has become buccally or distally displaced, presumably as a result of eruption of the tooth (Woo 2016 ; Regezi et al. 2017 ).

In a study from the United States of 2646 pericoronal lesions associated with impacted teeth, Curran et al. (2002 ) did not identify a single case of paradental cyst. They reported that 67% (1776 lesions) were diagnosed as normal follicular tissue and of the remaining pathologically significant lesions (n = 872), 86.6% (n = 752) were diagnosed as dentigerous cysts. This suggests that in this centre, paradental cysts were not recognised as an entity and were probably diagnosed as dentigerous cysts. The paper was challenged on this issue by Slater (2003 ), who suggested in correspondence that some of the dentigerous cysts diagnosed by Curran et al. (2002 ) may in fact be paradental cysts. It is not stated, however, how many of their impacted teeth were unerupted or partially erupted.

These discrepancies in frequency or prevalence are almost certainly due to uncertainty about the criteria for diagnosis and the fact that pericoronal radiolucencies associated with partially erupted third molars are often given a clinical or radiological diagnosis of ‘dentigerous cyst’, ‘pericoronitis’, or ‘hyperplastic follicle’. The pathologist may receive only fragments of inflamed tissue that may be consistent with any of these diagnoses, and paradental cyst may not be considered. The differential diagnosis of the paradental cyst and criteria for diagnosis will be discussed later in this chapter.