Читать книгу Shear's Cysts of the Oral and Maxillofacial Regions - Paul M. Speight - Страница 25

Frequency statistics differ from incidence studies in that they are not standardised against known population data, such as age, sex, and ethnicity. For data to be comparable between populations and internationally, age‐standardised incidence rates per 100 000 are compared with a standard world population. Incidence data are a requirement for all national cancer registries, but most benign lesions, including cysts, are not registered and thus incidence data is not available for the odontogenic cysts. Epidemiological data are therefore presented as the relative frequency of each cyst type as a proportion of the total number of cysts encountered within a population, or of the total number of specimens received. This gives clinicians an estimate of the likelihood of encountering these lesions in everyday practice.

Frequency studies are rarely based on the general population, but are usually derived from archival records of diagnoses made in a hospital department, usually pathology departments. While these provide useful data on the behaviour and treatment of different diseases, they are of limited use in international comparative studies. Table 1.3 shows the wide variation in the frequency of the three most common odontogenic cysts in different parts of the world. Almost without exception, these data are derived from retrospective analyses of pathology records and the frequency of each cyst type may depend on local protocols for patient referral and management, or even on individual pathologists' criteria for diagnosis. For example, a high frequency of radicular cysts may reflect a high caries rate in the local population, or a high rate of referral of periapical lesions. Conversely, a low frequency of radicular cysts may arise if the local practice is not to submit periapical lesions for histological analysis. In Chapter 4 we discuss the very low frequency of paradental cysts in some countries, where the lesion does not seem to be recognised as an entity and is therefore not diagnosed.

Tables 1.1 and 1.2 present our experience of the frequencies of jaw cysts in South Africa and the United Kingdom. Although the actual frequencies vary, the relative frequencies and the rank order of the lesions are very similar. In these studies, and in all studies worldwide (Table 1.3), the most common odontogenic cyst is the radicular cyst, followed by dentigerous cyst and then odontogenic keratocyst. The nasopalatine duct cyst is the most common non‐odontogenic cyst and in some studies has a similar frequency among all jaw cysts to the odontogenic keratocyst (Table 1.1). All the other cyst types are relatively rare.

These data show the relative frequency of each cyst as a proportion of all cyst types, but do not allow a clinician to determine how likely it is that they will encounter a cyst in everyday practice. Jones and Franklin (2006a ) reviewed over 44 000 histologically diagnosed oral and maxillofacial lesions in adults over a 30‐year period. Their data show that all the cyst types described in this book represent about 20% of all biopsies received (n = 8354). Odontogenic cysts were by far the most commonly encountered (n = 6052) and the overall most common cyst type in the maxillofacial regions was the radicular cyst. They found 3793 radicular cysts (including residual cyst), representing 8.6% of all biopsy specimens received. Dentigerous cysts represented 2.5% (n = 1081) of all biopsies, and odontogenic keratocyst was 1.3% (n = 591). By comparing these data to other commonly encountered lesions, a clinician can estimate the likelihood of encountering a cyst. Common diagnoses included 6458 cases of fibrous hyperplasia (14.7%), 2973 cases of lichen planus (6.8%), and 1901 epulides (4.3%; fibrous epulis, pyogenic granuloma, or giant cell epulis). During the same period, there were 3547 periapical granulomas, showing that the frequency of periapical granulomas (8.1%) and radicular cysts (8.6%) is similar. This was also suggested by Koivisto et al. (2012 ), who reviewed 9723 radiolucent lesions associated with the teeth (dentigerous cysts and lesions in the ramus were excluded) and found that 73% were periapical granulomas or cysts. There were 3215 (33.1%) radicular cysts and 3931 (40.4%) periapical granulomas. The next most common lesion was the odontogenic keratocyst (8.8%; n = 857).

Table 1.1 Distribution of 3481 jaw cysts according to diagnosis.

Source: Data courtesy of Prof. M. Shear, University of Witwatersrand.

	n	% of group	% of all cysts
Odontogenic cysts
Radicular/residual cyst	1825	60.6	52.4
Dentigerous cyst	599	19.9	17.2
Eruption cyst	27	0.9	0.8
Odontogenic keratocyst (including orthokeratinised odontogenic cysts)	355	11.8	10.2
Inflammatory collateral cysts	109	3.6	3.1
Calcifying odontogenic cyst	28	0.9	0.8
Lateral periodontal cyst	24	0.8	0.7
Gingival cyst of adults	21	0.7	0.6
Unclassified	18	0.6	0.5
Glandular odontogenic cyst	6	0.2	0.2
	3012	100.0
Non‐odontogenic cysts
Nasopalatine duct cyst	404	86.1	11.6
Simple bone cyst	35	7.5	1.0
Nasolabial cyst	21	4.5	0.6
Surgical ciliated cyst	5	1.1	0.1
Mucosal cyst of maxillary antrum	4	0.9	0.1
	469	100.0
Total	3481		100.0

Table 1.2 Distribution of 7121 odontogenic cysts in a United Kingdom population.

Source: Data from Jones et al. (2006 ).

Cysts	n	%
Radicular cyst	3724	52.3
Residual cyst	573	8.0
Dentigerous cyst	1292	18.1
Eruption cyst	15	0.2
Odontogenic keratocyst (including orthokeratinised odontogenic cysts)	828	11.6
Inflammatory collateral cysts	402	5.6
Unclassified odontogenic cysts	210	2.9
Lateral periodontal cyst	28	0.4
Calcifying odontogenic cyst	21	0.3
Gingival cyst of adults	16	0.2
Glandular odontogenic cyst	11	0.2
Gingival cyst of infants	1	0.0
Total	7121	100.00

Table 1.3 Frequency (%) of the three most common odontogenic cysts in selected case series with a wide geographical distribution.

References	Country	N	Radicular cyst a	Dentigerous cyst b	Odontogenic keratocyst	Other	Males (%)
Daley et al. (1994 )	Canada	6847	65.2	24.1	4.9	5.8	NR
Mosqueda‐Taylor et al. (2002 )	Mexico	856	42.1	33.0	21.5	3.4	53.1
Meningaud et al. (2006 )	France	695	58.2	22.3	19.1	0.5	65.0
Jones et al. (2006 )	UK	7121	60.3	18.4	11.6	8.1	55.9
Ochsenius et al. (2007 )	Chile	2944	61.9	18.5	14.3	5.3	52.8
Grossmann et al. (2007 )	Brazil	2812	63.0	26.1	7.4	3.5	50.0
Tortorici et al. (2008 )	Italy (Sicily)	1273	84.5	11.4	1.3	2.8	53.9
Ali (2011 )	Kuwait	196	52.6	26.0	15.3	6.1	57.6
Sharifian and Khalili (2011 )	Iran	1227	45.8	24.7	19.4	10.1	57.1
Ramachandra et al. (2011 )	India	252	50.3	22.4	27.4	NI	61.2
Manor et al. (2012 )	Israel	285	56.1	28.8	8.0	7.0	59.7
Soluk Tekkesin et al. (2012b )	Turkey	5003	65.6	10.6	20.9	2.9	57.6
Tamiolakis et al. (2019 )	Greece	5165	73.2	14.8	8.4	3.6	61.5
Bhat et al. (2019 )	India	125	60.8	22.4	13.6	3.2	67.9
Kammer et al. (2020 )	Brazil	406	53.4	14.0	15.0	17.5	56.7
Aquilanti et al. (2021 )	Italy	2150	57.0	23.5	13.0	6.5	63.3

N, total number of odontogenic cysts – frequencies are proportions of odontogenic cysts only; NI, not included – proportions only given for the three main cyst types; NR, not reported.

^a Data for radicular cyst includes residual cysts.

^b Data for dentigerous cyst includes eruption cysts.

Among other cyst types, Jones and Franklin (2006a ) found that the most common were mucoceles (3.9%; n = 1720), while all other cysts were rare (less than 1.0%).

These data show that cysts are relatively common and that the most commonly encountered are the radicular cyst, dentigerous cyst, and mucoceles. They also suggest that when a periapical radiolucency is seen, about 50% will be a radicular cyst and 50% will be a periapical granuloma. Details of the frequency and incidence of each cyst type are illustrated and discussed in the following chapters.