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Keratinization of radicular cyst epithelial lining or occurrence of odontogenic keratocyst in the periapical region?
Int. J. Oral Maxillofac. Surg. 1987: 16:593-595 (Key words:
keratocyst, odontogenie)
Keratinization of radicular cyst epithelial lining or occurrence of odontogenic keratocyst in the periapical region? ZORAN STAJCI(~ AND ANDRIJA PALJM*
Oral Surgery Clinic & Department of Oral Pathology*, Faculty of Stomatology, University of Beograd, Yugoslavia
ABSTRACT-- Sections of 565 radicular cysts were examined for keratinization of epithelium. 4 cysts showed keratinization, 2 of ortho and 2 of para type. Due to other histological features typical for odontogenic keratocysts, it was concluded that these cysts were odontogenic keratocysts that occurred in the periapical region of the involved teeth.
(Accepted for publication 30 Defember 1986)
It has been reported that the epithelial lining o f radicular cysts m a y become keratinized by metaplasiag; however, the incidence o f such an occurrence is not known. Similarly, odontogenic keratocysts m a y present as isolated periapical lesions ~,H. The aim o f this study was to determine the incidence of keratinization o f radicular cyst a n d / o r the prevalence o f odontogenic keratocysts o f the periapical region.
Material and methods Histological (H & E) section~ of 565 consecutive radicular cysts removed from patients attending the Oral Surgery Clinic were examined for keratinization of the epithelium. The classification of radicular cyst was based on clinical and radiographical examination. Only periapical cysts of non-vital teeth which were
either endodontically treated or extracted during the operation were used for this study. In cysts with keratinization of the epithelium, histologically the type of keratinization, the thickness of the epithelium (in cell numbers), the presence of epithelial islands/daughter cysts as well as the inflammation in the connective tissue wall were noted.
Results Histological examination revealed 4 clinically diagnosed radicular cysts with keratinization o f the epithelial lining. 2 cysts were found in the maxilla a r o u n d the roots o f the lateral incisor and second p r e m o l a r and other 2 in the m a n d i b l e a r o u n d the roots o f the second m o l a r and first premolars. 2 cysts were lined by ortho- (Fig. 1) and other 2 by parakeratinized stratified squamous
594
STAJ(~I(2 AND PALJM
Fig. 1. Photomicrograph of orthokeratinized keratocyst (periapical), H & E × 200.
Fig. 2. Photomicrograph of parakeratinized keratocyst (periapical), H & E x 200.
epithelium (Fig. 2). In all cases, the epithelium was thin, consisting of 3 7 cell layers and without the rete pegs. Basal cell layers were well-defined. Separation of the stroma from the basal layer was noted in 3 samples. Inflammation in the connective tissue wall was observed only in 1 case and was confined to a small region.
seen in radicular cysts. Thus, these cysts are odontogenic keratocysts that occurred in the periapical region of the involved teeth and not radicular cysts with epithelial lining keratinized by metaplasia. This means that the incidence of keratinization in our material is zero, which is in accordance with previously reported studies 5,6. It can be concluded that it is more likely that odontogenic keratocysts occur in the periapical region. Our study shows that the incidence of odontogenic keratocysts in the periapical region of teeth with non-vital pulp is 0.7% of all clinically and radiographically verified radicular cysts. These results are very similar to those reported by BRANNON2 and BUSCH3. The former found that 0.5% of histologically verified odontogenic keratocysts were clinically and radiographically diagnosed as apical periodontal cysts. The latter found 4 radicular keratocysts (0.5%) among a mixed series of 820 odontogenic cysts. More recently, CHUONG et al. 4 reported an even higher incidence of odontogenic keratocysts in the periapical region, since they found that out of 28 odontogenic keratocysts, 2 were of the radicular type (7%). With respect to the clinical behaviour of odontogenic keratocysts, the present find-
Discussion When the term odontogenic keratocyst was introduced in the literature, it was initially applied to cysts of odontogenic origin having a keratinized epithelial lining. P I ~ BORG & HANSEN8 pointed out the high recurrence rate of keratoeysts and therefore it was believed that the presence of keratin was responsible for their clinical behaviour. HJORTING-HANSEN et al. 6 showed that keratocysts in the jaws were of non-inflammatory origin. There is now a great deal of evidence that the odontogenic keratocyst is a distinct entity of developmental origin 7,~°. With regard to the histological patterns of the 4 radicular cysts which were found to show keratinized epithelium in this study, they had other characteristics (thin epithelium without rete pegs, absence of inflammation in the wall etc.) which are rarely
KERATOCYSTS ings indicate that regardless of its clinical appearance, every radicular cyst should be examined histologically, since 0.5% or more may prove to be true odontogenic keratocyst. Acknowledgement - The authors would like to express their sincere gratitude to Dr. Vlastimir Petrovi6 as well as to undergraduate students of Stomatology Aleksandar Todorovi6 and Neboj~a Avram for their valuable assistance.
References 1. ARWILL,T. & KAHNBERG,K. E.: Odontogenic keratocyst associated with an intramandibular chondroma. J. Oral Surg. 1977: 35: 64-67. 2. BRANNON, R. B.: The odontogenic keratocyst. A clinicopathologic study of 312 cases. Part 1. Clinical features. Oral Surg. 1976: 42: 54-72. 3. BUSCH, H. G. (1969) quoted by ARWILL & KAHNBERG1. 4. CHUONG, R., DONOFF, R. B. & GURALNICK, W.: The odontogenic keratocyst. J. Oral Maxillofac. Surg. 1982: 40: 797-802.
595
5. DONOFF, R. B., GURALNICK,W. ,~ CLAYMAN, L.: Keratocysts of the jaws. J. Oral Surg. 1972: 30: 800-804. 6. HJORTING-HANSEN, E., ANDREASEN,J. O. & ROa~NSON, L. H.: A study of odontogenic cysts, with special reference to location of keratocysts. Br. J. Oral Surg. 1969: 7: 15-23. 7. MAIN,D. M. G.: Epithelial jaw cysts: 10 years of the WHO classification. J. Oral Pathol. 1985: 14: 1-7. 8. PINDBORG, J. J. & HANSEN, J.: Studies on odontogenic cyst epithelium. 2. Clinical and roentgenological aspects of odontogenic keratocysts. Acta Path. Microbiol. Scand. 1963: 58: 283-294. 9. SHEAR, M.: Cysts of the oral region. John Wright & Sons, Bristol 1983 pp. 4-34. 10. SHEAR, M.: Cysts of the jaws. Recent advances. J. Oral Pathol. 1985: 14: 43-59. 11. WRIGHT, B. A., WYSOCKI, G. E & LADER, T. C.: Odontogenic keratocysts presenting as periapical disease. Oral Surg. 1983: 56: 425-429. Address: Zoran Staj~i~ Oral Surgery Clinic Faculty of Stomatology, FAH 506 Dr. SubotiOa 4, 11000 Beograd Yugoslavia
keratocyst, odontogenie)
Keratinization of radicular cyst epithelial lining or occurrence of odontogenic keratocyst in the periapical region? ZORAN STAJCI(~ AND ANDRIJA PALJM*
Oral Surgery Clinic & Department of Oral Pathology*, Faculty of Stomatology, University of Beograd, Yugoslavia
ABSTRACT-- Sections of 565 radicular cysts were examined for keratinization of epithelium. 4 cysts showed keratinization, 2 of ortho and 2 of para type. Due to other histological features typical for odontogenic keratocysts, it was concluded that these cysts were odontogenic keratocysts that occurred in the periapical region of the involved teeth.
(Accepted for publication 30 Defember 1986)
It has been reported that the epithelial lining o f radicular cysts m a y become keratinized by metaplasiag; however, the incidence o f such an occurrence is not known. Similarly, odontogenic keratocysts m a y present as isolated periapical lesions ~,H. The aim o f this study was to determine the incidence of keratinization o f radicular cyst a n d / o r the prevalence o f odontogenic keratocysts o f the periapical region.
Material and methods Histological (H & E) section~ of 565 consecutive radicular cysts removed from patients attending the Oral Surgery Clinic were examined for keratinization of the epithelium. The classification of radicular cyst was based on clinical and radiographical examination. Only periapical cysts of non-vital teeth which were
either endodontically treated or extracted during the operation were used for this study. In cysts with keratinization of the epithelium, histologically the type of keratinization, the thickness of the epithelium (in cell numbers), the presence of epithelial islands/daughter cysts as well as the inflammation in the connective tissue wall were noted.
Results Histological examination revealed 4 clinically diagnosed radicular cysts with keratinization o f the epithelial lining. 2 cysts were found in the maxilla a r o u n d the roots o f the lateral incisor and second p r e m o l a r and other 2 in the m a n d i b l e a r o u n d the roots o f the second m o l a r and first premolars. 2 cysts were lined by ortho- (Fig. 1) and other 2 by parakeratinized stratified squamous
594
STAJ(~I(2 AND PALJM
Fig. 1. Photomicrograph of orthokeratinized keratocyst (periapical), H & E × 200.
Fig. 2. Photomicrograph of parakeratinized keratocyst (periapical), H & E x 200.
epithelium (Fig. 2). In all cases, the epithelium was thin, consisting of 3 7 cell layers and without the rete pegs. Basal cell layers were well-defined. Separation of the stroma from the basal layer was noted in 3 samples. Inflammation in the connective tissue wall was observed only in 1 case and was confined to a small region.
seen in radicular cysts. Thus, these cysts are odontogenic keratocysts that occurred in the periapical region of the involved teeth and not radicular cysts with epithelial lining keratinized by metaplasia. This means that the incidence of keratinization in our material is zero, which is in accordance with previously reported studies 5,6. It can be concluded that it is more likely that odontogenic keratocysts occur in the periapical region. Our study shows that the incidence of odontogenic keratocysts in the periapical region of teeth with non-vital pulp is 0.7% of all clinically and radiographically verified radicular cysts. These results are very similar to those reported by BRANNON2 and BUSCH3. The former found that 0.5% of histologically verified odontogenic keratocysts were clinically and radiographically diagnosed as apical periodontal cysts. The latter found 4 radicular keratocysts (0.5%) among a mixed series of 820 odontogenic cysts. More recently, CHUONG et al. 4 reported an even higher incidence of odontogenic keratocysts in the periapical region, since they found that out of 28 odontogenic keratocysts, 2 were of the radicular type (7%). With respect to the clinical behaviour of odontogenic keratocysts, the present find-
Discussion When the term odontogenic keratocyst was introduced in the literature, it was initially applied to cysts of odontogenic origin having a keratinized epithelial lining. P I ~ BORG & HANSEN8 pointed out the high recurrence rate of keratoeysts and therefore it was believed that the presence of keratin was responsible for their clinical behaviour. HJORTING-HANSEN et al. 6 showed that keratocysts in the jaws were of non-inflammatory origin. There is now a great deal of evidence that the odontogenic keratocyst is a distinct entity of developmental origin 7,~°. With regard to the histological patterns of the 4 radicular cysts which were found to show keratinized epithelium in this study, they had other characteristics (thin epithelium without rete pegs, absence of inflammation in the wall etc.) which are rarely
KERATOCYSTS ings indicate that regardless of its clinical appearance, every radicular cyst should be examined histologically, since 0.5% or more may prove to be true odontogenic keratocyst. Acknowledgement - The authors would like to express their sincere gratitude to Dr. Vlastimir Petrovi6 as well as to undergraduate students of Stomatology Aleksandar Todorovi6 and Neboj~a Avram for their valuable assistance.
References 1. ARWILL,T. & KAHNBERG,K. E.: Odontogenic keratocyst associated with an intramandibular chondroma. J. Oral Surg. 1977: 35: 64-67. 2. BRANNON, R. B.: The odontogenic keratocyst. A clinicopathologic study of 312 cases. Part 1. Clinical features. Oral Surg. 1976: 42: 54-72. 3. BUSCH, H. G. (1969) quoted by ARWILL & KAHNBERG1. 4. CHUONG, R., DONOFF, R. B. & GURALNICK, W.: The odontogenic keratocyst. J. Oral Maxillofac. Surg. 1982: 40: 797-802.
595
5. DONOFF, R. B., GURALNICK,W. ,~ CLAYMAN, L.: Keratocysts of the jaws. J. Oral Surg. 1972: 30: 800-804. 6. HJORTING-HANSEN, E., ANDREASEN,J. O. & ROa~NSON, L. H.: A study of odontogenic cysts, with special reference to location of keratocysts. Br. J. Oral Surg. 1969: 7: 15-23. 7. MAIN,D. M. G.: Epithelial jaw cysts: 10 years of the WHO classification. J. Oral Pathol. 1985: 14: 1-7. 8. PINDBORG, J. J. & HANSEN, J.: Studies on odontogenic cyst epithelium. 2. Clinical and roentgenological aspects of odontogenic keratocysts. Acta Path. Microbiol. Scand. 1963: 58: 283-294. 9. SHEAR, M.: Cysts of the oral region. John Wright & Sons, Bristol 1983 pp. 4-34. 10. SHEAR, M.: Cysts of the jaws. Recent advances. J. Oral Pathol. 1985: 14: 43-59. 11. WRIGHT, B. A., WYSOCKI, G. E & LADER, T. C.: Odontogenic keratocysts presenting as periapical disease. Oral Surg. 1983: 56: 425-429. Address: Zoran Staj~i~ Oral Surgery Clinic Faculty of Stomatology, FAH 506 Dr. SubotiOa 4, 11000 Beograd Yugoslavia