A clinical and histologic observation of enamel hypoplasia in a case of epidermolysis bullosa hereditaria

A clinical and histologic observation of enamel hypoplasia in a case of epidermolysis bullosa hereditaria Hiroaki DEPARTMENT SCHOOL

Koshiba, OF

Okio Kimura, PEDODONTICS,

and Minciru Nakata, TOKYO

MEDICAL

AND

Tokyo, Japan DENTAL

UNIVERSITY,

OF DENTISTRY

The nature of the enamel defects in a patient with epidermolysis bullosa hereditaria dystrophica was observed by light microscopy, microradiography, and scanning electron microscopy (SEM) so that by these means more detailed information could be obtained. The random distribution of the round shape of the hypoplastic defects of enamel with hypomineralisation, in which there is a continuity of the incremental lines, suggested the possibility that some ameloblasts maintained hypoaetivity of their secretory function during their total life span.

E

pidermolysis bullosa hereditaria is characterized by a marked development. of vesicles in ectodermal tissues. The vesicles may appear spontaneously or as a consequence of trauma. Three types of this disease are recognized at present: letalis, dystrophica, and a simplex form. Involvement of the dental hard tissues has been observed in only epidermolysis bullosa hereditaria letalis and dystrophica. In both types, the enamel surfaces of the teeth have, clinically, a pitted hypoplastic appearance.lb3 Histologic examination of the teeth shows that the enamel is very thin and has an uneven surface. Observation of the tooth germs reveals the presence of many globular inclusions in the enamel organ.4-7 The histologic reports in these cases were based on conventional light microscopy. In the present study of the nature of the enamel defects in a patient with epidermolysis bullosa hereditaria dystrophica, we thought that more detailed information might be obtained by the use of scanning electron microscopy (SEM) as an additional method of examination. CASE REPORT The patient, a boy, was 10 years old when first given a dental examination. He was the third son of healthy parents who were consanguineous first cousins. No other member of the family had shown symptoms of epidermolysis bullosa hereditaria dystrophica. No abnormality was detected either during the mother’s pregnancy or at the time of her delivery. The boy’s birfh weight was 3,250 grams.

585

586

Koshiba,

Kimwm,

Fig. 1. The permanent enamel hypoplasia, except

Fig.

d. Maxillary

mad Nakatcl

for

and deciduous the maxillary

premolar

teeth have a conical left deciduous teeth.

immediately

after

Vesicles and erosions appeared first on the skin and the lesions gradually extended and covered large toenails were normal at birth but exfoliated after bullosa hereditaria dystrophica. Present

showing

and

globular

all are

Burg. 19i7

pitted,

with

surface

enamel.

under the lower lip 1 month after birth, portions of the body. The flngernails and 1 year. The diagnosis was epidermolysis

condition

At 10 years of age the patient weighed proximately the mean weight and height of which had been induced by trauma, that is, and soles of the feet. His facial appearance nature of the sparse hair on the head. Most scarred “nail-like” residues present. Oral

eruption,

shape

Oral April,

26 kilograms and was 131 cm. tall. These are apJapanese children at 9 years of age. Some bullae, by scratching, were scattered on the face, hands, was normal, except for some scars and the bristly fingernails and toenails were missing, with only

examination

The palate had a relatively high vault. A moderate inflammatory reaction was observed in the gingival papillae, and a large amount of dental plaque was present on the erupted teeth (Fig. 1). Some bullae were seen in the muscosa of the lower lip. Although the yellow enamel surfaces of the left maxillary deciduous central and lateral incisors were smooth from abrasion, the other teeth had numerous small pits on the labial and lingual surfaces; however, the occlusal surfaces of the latter teeth were smooth (Fig. 1). The enamel surfaces of the permanent teeth immediately after eruption, such as the left maxillary first and second premolars, had a globular configuration (Fig. 2). Intraoral roentgenograms (Fig. 3) showed that on both the deciduous and permanent teeth

Volume Number

Enamel

43 4

Fig. 9. Panoramic permanent teeth. The teeth is also seen.

hypoplasia

in epidermolysis

radiograph showing quite thin enamel globular surface structure of the enamel

bullosa

587

for both the deciduous and of the unerupted permanent

Pig. 4. A longitudinal ground section of a mandibular left lateral incisor showing the wavy enamel surface which decreases in thickness toward the top of the cusp (+). Dentin is normal. (Original magnification, x40.) Fig. 5 Microradiograph of the same section shown in Fig. 4, revealing hypomineralization of the area corresponding to the hypoplastic enamel. the enamel was quite thin peared to have the surface because of the deposition Histologic

observation

The specimens, incisor,

or absent. The crowns of the unerupted permanent teeth also apcovered by small globules. The coronal pulp was narrow, probably of secondary dentin resulting from the marked attrition.

four

maxillary

which

consisted of six exfoliated teeth deciduous molars, and a mandibular

(maxillary left deciduous left lateral incisor), all

central showed

6. SEM of the enamel surface from t,he other half of the specimen illustrate d in 4 and 5, showing the round defects randomly distributed. Fig. 7. SEM of the cut surface of the specimen shown in Fig. 6, showing the 3 wavy en; amel surf ace. Fig.

Figs.

typically r pitted defects neutrali aed with calcium halves, cme of which was used for . examination by polished with y-aluminum cent hyd lrochlorie acid for

of the enamel. The specimens were !ixed in 10 per cent forn ralin carbonate. The teeth were sliced longitudinally mesiodir stally into two prepared for ground section and microradiography and the other was scanning electron microscopy (SEM). The cut surface was care: fully abrasive powder. The specimens were etched with a sob rtion of 5 per30 seconds in order to enhance topographic contrast an d then wa

Volume Number

43 4

Fig. 8. High incremental lines

Enamel

magnification of the border of the enamel.

hypoplasia

of the typically

in epidermolysis

pitted

enamel

bullosa

showing

589

the curved

in tap water. The specimens were then dried, glued on to specimen stubs, and coated with carbon and gold for examination by SEM. The polished ground sections, approximately 50 c in thickness, were prepared for contact microradiography and optical microscopy. Histologic examination revealed that the yellow-colored tooth surfaces had many pits. Careful examination of the ground sections confirmed the presence of a thin layer of enamel, about 6 c in thickness, at the lower border of the pits. This formed the minimum thickness of the enamel layer; the maximum thickness of the enamel was 30 c at the cervical region. The thickness of the enamel at the tip of the cusp was thinner than that of the cervical region (Figs. 4 and 7). At the base of the pitted areas, the enamel appeared to be layered in a lamellar fashion near the enamel-dentin junction and to be amorphous closer to the outer surface (Fig. 4). The orientation of enamel rods was quite interesting in that they were directed toward the border of the pits, similar to the orientation of the enamel rods in the occlusal grooves of normal teeth (Fig. 8). The incremental lines of the enamel became narrower in the superficial layer of enamel at the bottom of the pit. The enamel in the region of the pit was confirmed mieroradiographically to be hypomineralized. Radiolucent areas contained lamellar radiopaque striae near the enamel-dentin junction, and these were curved near the surface of enamel (Fig. 5). SEM indicated that there was organic matrix in the depth of some of the pits, and so-called prism ends of the enamel in other pits. The pits were round in shape (Fig. 6). The dentin appeared to have a normal structure, and the enamel-dentin junction was relatively smooth.

DISCUSSION Witkop and Rao3 suggested that the enamel pits in epidermolysis bullosa hereditaria had an octagonal outline and resembled the pits of a honeycomb. The present observations with SEM revealed that the pits were round. The crowns of newly erupted permanent teeth were covered by small globular enamel nodules (Fig. 2). However, the crowns of the functional deciduous teeth were smooth but covered with pits (Fig. 6). This difference in the morphology between the deciduous and permanent crown surfaces is considered to be due to abrasion, with

590

Koshiba,

Kimnru,

Oral April,

trml Nakatn

Surg. 19i7

the enamel nodules of the deciduous crowns having been worn down so as to leave only the pits. Pathologic alteration of the teeth and of the tooth germs in this disease has been investigated in detail by a number of authors”, 5, 7 who observed that the enamel was both hypoplastic and hypomineralized, and its structure was lamellarlike and almost without prisms. In the present case, the area of enamel hypoplasia corresponded with the hypomineralized area, and in these regions the incremental lines of the enamel followed a wavy course. With regard to the hypoplastic contour of the enamel surface, BoydeS noted the presence of normal ends of enamel rods even in the deepest part of hypoplastic defects in a case of “ring” enamel hypoplasia due to fever or some other major disturbance in the whole body metabolism. He suggested, therefore, that the ameloblast which was actively forming the enamel stopped its function or modified its activity quite suddenly for some reason. However, Sauk and his colleagues” suspected that the genetically determined enamel hypoplasia was induced by vascular defects of the dental organ rather than by alteration of the ameloblasts. In other words, the causal factor may be a change in the environment of the tooth germs. The random distribution of the hypoplastic defects of enamel with hypomineralization, which possess a continuity of the incremental lines, points to the possibility that some ameloblasts had reduced activity at the time of matrix formation and perhaps even at the time of calcification. That is to say, these amcloblasts maintained hypoactivity of their secretory function during their total life span. We wish to thank who read the manuscript

Prof. R. W. Fearnhead, of the London and made many valuable suggestions.

Hospital

of

Dental

Anatomy,

REFERENCES 1. Kaslick, 2. Boyer,

R. S., and Brustein, H. C.: Epidermolysis H. E., and Owens, R. H.: Epidermolysis

Bullosa, ORAL SURG. 14: 1315-133Q, 1961. Bullosa: A Rare Disease of Dental Interest,

ORAL SURG. 14: 1170-1177, 1961. 3< . Witkop,

C. J., and Rao, S.: Inherited Defects in Tooth Structure. In Bergama, D. (editor) : The Third Conference on the Clinical Delineation of Birth Defects. Part XI. Orofacial Structures. Birth Defects Oriainal Article Series. National Foundation March of Dimes, Baltimore, 1971, Williams & WTlkins Company, Vol: 7, pp. 153-184. 4. Delaire, J., Kerebel, B., and Billet, J.: Manifestations bucco-dentaires des epidermolyses, Rev. Stomatol. 61: 189-200, 1960. 5. Arwill, T., Bergenholtz, A., and Olsson, 0.: Epidermolysis Bullosa Hereditaria, ORAL SURG.

19: 723-744. 1965.

6. Brain,

E.-B., and Wigglesworth, J. S.: Developing Teeth in Epidermolysis Bullosa Hereditaria Letalis: A Histological Study, Br. Dent. J. 124: 255-260, 1968. 7. Gardner. D. G.. and Hudson. C. D.: The Disturbances in Odontoaenesis in Euidermolvsis A Bullosa ‘Hereditaria Letalis, &AL SURF. 40: 483-493, 1975. 8. Boyde, A.: The Surface of the Enamel in Human Hypoplastic Teeth, Arch. Oral Biol. 15: 897-899, 1970. 9. Sauk, J. J., Vickers, R. A., Copeland, J. S., and Lyon, H. W.: The Surface of Genetically Determined Hypoplastic Enamel in Human Teeth, ORAL SURG. 34: 60-68, 1972. Reprint

requests

to:

Dr. Hiroaki Koshiba Department of Pedodontics Tokyo Medical and Dental University Bunkyo-ku, Yushima, l-5-45 Tokyo, Japan

School

of Dentistry