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Dilaceration of a mandibular permanent incisor
ORAL
PATHOLOGY
General Section .
.
.
.
.
.
DILACERATION
.
.
.
.
.
.
OF A MANDIBULAR
.
.
.
.
.
PERMANENT
.
.
.
...*
INCISOR
Report of a Case
Prunces B. Glenn, D.D.S.,” Miami, Fin., nno’ Ha,rold R. Stanley. Jr., D.D.S.. X.S., B.S.,**
Bethesda, Mid.
to the developing tooth germ is infrequent, as the tooth germs are well I protected. The deciduous teeth are insulated from trauma by the bony crypts NJURY
in which they form, and the permanent ones are protected either by crypts or by the roots of the deciduous teeth. Surgical trauma from the extraction of deciduous teeth rarely produces injury to permanent crowns, for the latter are usually completely formed before carious involvement is severe enough to IVquire extraction. More common are deformities that, result from the displacement of the partly formed tooth due to accidental fracturing of the maxilla Or mandible1 and other injuries sustained by children, particularly to the anterior part of the mouth. Glenn* has previously shown that injuries to the incisors of children most often accompany falls involving steps and sidewalks. Sauntone3 experimented wit,h cats, producing trauma at different st,ages01’ tooth development. The end result depended upon the stage of differentiation of the tooth germ at the time of injury. In early development, when ~~11 differentiation had not progressed very far, the injured area of the enamel org;n~ was replaced by undifferentiated mesenchymal cells. During later development of the tooth, at a time when dentine had been deposited, the injured part v-as repaired by the production of an osteoid substance. After the tooth tissue lmtl completely differentiated, the lost dentine and enamel were replaced by young connective tissue from the dental follicle. If a calcified tissue was nc~etlcdto restore the continuity of a tooth, osteodentine (rat,her than typical tooth sltl~ stances) was always produced. ‘Formerly D. C. **National Service, United in&on,
Resident
in Pedodontia,
Children’s
Hospital
Institute of Dental Research, National States Department of Health, Education, 1249
of the District
of Columbkt,
R’asl,-
Institutes of Health, Public He;iltl, and Welfare, Bethesda, Marylan
GLENN
AND
STANLEY
OS., U.M. & O.P. October,
1960
Displacement of the partly formed tooth is not uncommon. The calcified portion of the unerupted tooth may be forced into the developing soft part, causing telescoping or a so-called impacted dislocation. In other instances pressure exerted either by the crowding of a neighboring tooth or by orthodontic means may force the partly or completely erupted tooth into a diff’erent location If the root is not completely formed, the unthan that originally intended. calcified part will bend, twist, or sometimes angulate sharply to result in the deformity known as di1aeera.tion.l An unusual case in which injury during infancy resulted in damage to a developing permanent tooth follows. CASE REPORT At 18 months of age, patient G. W. G. (now 7 years old) fell on the sidewalk, striking the anterior section of the mandible. According to her parents, the labial alveolar plate of The available history did not the mandible was fractured and was sutured into position. indicate whether the deciduous incisors themselves mere fractured, but they were apparently retained for some time. When the permanent lower right central incisor first began to erupt, the parents noticed that the tooth was developing in a “flattened position.”
Fig. I.-An
intraoral
roentgenogram. Note the bend of the tooth and the more opaque structure within the tooth that resembles a miniature tooth.
Clinical examination showed the crown to be erupting labially and in an almost horizontal position. The incisal edge protruded into the lower lip area when the mouth was in a closed, relaxed position. Incisal contact or function with the maxillary incisors when the jaws were in centric occlusion was not possible. The patient stated that the tooth seemed to be loose periodically and also that it was sensitive to cold beverages. On several occasions, because of the abnormal location of the incisal edge, the child injured her lower lip during play. Intraoral roentgenograms suggested a bend of the tooth at the cervical area of the crown (Fig. 1). Roentgenographically, the tooth also resembled a dens in dente. Because of the extreme anterior crowding, sensitivity, lack of function, and the fact that a crown preparation could not be accomplished without an unusual root canal procedure, the tooth was removed. The direction of force of the forceps was in line with the root and not the crown. Upon extraction, the incisor was noted to be boot-shaped, the crown apparently joining the root at almost a right angle (Fig. 2). Microscopic examination revealed that the cervical point of the dentinoenamel junction extended into the center of the coronal pulp (Fig. 3). A large projection of osteodentine
Volume Number
Ii
I I)
DILACERATION
Fig. 2.-The specimen the dentinoenamel junction chamber. A large projection (Magnification, x9, reduced
OF MANDIBULAR
PERUANF,NT
TNCISOR
1251
The cervical point of is obviously boot-shaped in appearance. is located within the approximat? center of the coronal pulp of osteodentine extends apically from the point of penetration. 1/.)
Fig. 3.-A higher-power view of the specimen shown in Fig. 2. Point a originally joined Remaining enamel matrix is seen at e. The dotted line represents the division point b. between dentine formed before and after the traumatic episode. The delineation resembles a neonatal line as seen in deciduous teeth. Points r locate foci of resorption where oAont.oclnsts were found. (Magnification, X20; reduced %.)
1252
GLENN
AND
STANLEY
OS.. O.M. & O.P. Octolrer, 1961)
reached apically from this point (Figs. 2 and 3). As illustrated in Fig. 2, point a originally joined point b. The sliver at point e is all that remained of the enamel matrix after dccalcification. Except for the central projection of irregular dentine within the pulp, the remaining dentinc was primary in character. However, thcrc could be seen a division in the primary dentine of the crown (Figs. 2 and 3) which probably represented the amounts of dentine formation completed before and after the timo of injury. This delineation gives the appearance of a neonatal line, as seen in deciduous teeth. The areas at points r revealed foci of resorption due to odontoclastie activity. DISCUSSION
According to Ellis,4 the defect will appear at the junction of the crown and root or within the root of the tooth itself, depending upon the stage or age of development of the tooth at the time of the disturbance. In the case just described the almost 90 degree bend of the crown to the root gives interesting support to that premise. At the time of injury the tooth bud was bent in such a fashion that the cervical point of the dentinoenamel junction was evidently forced into the center of the pulp chamber at the cervical level. The pulp tissue, in response to the presence of this structure, laid down a large projection of osteodentine within the pulp chamber which created the illusion in the roentgenogram of a dens in dente. REFERENCES
1. Thoma,
Kurt H.: Oral Pathology, ed. 4, St. Louis, 1954, The C. V. Mosby Company, pp. 79-81. 2. Glenn, F.: Oral Injuries in Children, a Census Study, Clin. Proc. Child. Hosp., Wash. 13: 197, 1957. 3. Sauntone, P.: Cited by Thorna+ pp. 79-80. and Treatment of Injuries to the Teeth of Children, ed. 3, 4. Ellis, R.: The Classification Chicago, 1952, The Year Book Publishers, Inc., pp. 231-236.
PATHOLOGY
General Section .
.
.
.
.
.
DILACERATION
.
.
.
.
.
.
OF A MANDIBULAR
.
.
.
.
.
PERMANENT
.
.
.
...*
INCISOR
Report of a Case
Prunces B. Glenn, D.D.S.,” Miami, Fin., nno’ Ha,rold R. Stanley. Jr., D.D.S.. X.S., B.S.,**
Bethesda, Mid.
to the developing tooth germ is infrequent, as the tooth germs are well I protected. The deciduous teeth are insulated from trauma by the bony crypts NJURY
in which they form, and the permanent ones are protected either by crypts or by the roots of the deciduous teeth. Surgical trauma from the extraction of deciduous teeth rarely produces injury to permanent crowns, for the latter are usually completely formed before carious involvement is severe enough to IVquire extraction. More common are deformities that, result from the displacement of the partly formed tooth due to accidental fracturing of the maxilla Or mandible1 and other injuries sustained by children, particularly to the anterior part of the mouth. Glenn* has previously shown that injuries to the incisors of children most often accompany falls involving steps and sidewalks. Sauntone3 experimented wit,h cats, producing trauma at different st,ages01’ tooth development. The end result depended upon the stage of differentiation of the tooth germ at the time of injury. In early development, when ~~11 differentiation had not progressed very far, the injured area of the enamel org;n~ was replaced by undifferentiated mesenchymal cells. During later development of the tooth, at a time when dentine had been deposited, the injured part v-as repaired by the production of an osteoid substance. After the tooth tissue lmtl completely differentiated, the lost dentine and enamel were replaced by young connective tissue from the dental follicle. If a calcified tissue was nc~etlcdto restore the continuity of a tooth, osteodentine (rat,her than typical tooth sltl~ stances) was always produced. ‘Formerly D. C. **National Service, United in&on,
Resident
in Pedodontia,
Children’s
Hospital
Institute of Dental Research, National States Department of Health, Education, 1249
of the District
of Columbkt,
R’asl,-
Institutes of Health, Public He;iltl, and Welfare, Bethesda, Marylan
GLENN
AND
STANLEY
OS., U.M. & O.P. October,
1960
Displacement of the partly formed tooth is not uncommon. The calcified portion of the unerupted tooth may be forced into the developing soft part, causing telescoping or a so-called impacted dislocation. In other instances pressure exerted either by the crowding of a neighboring tooth or by orthodontic means may force the partly or completely erupted tooth into a diff’erent location If the root is not completely formed, the unthan that originally intended. calcified part will bend, twist, or sometimes angulate sharply to result in the deformity known as di1aeera.tion.l An unusual case in which injury during infancy resulted in damage to a developing permanent tooth follows. CASE REPORT At 18 months of age, patient G. W. G. (now 7 years old) fell on the sidewalk, striking the anterior section of the mandible. According to her parents, the labial alveolar plate of The available history did not the mandible was fractured and was sutured into position. indicate whether the deciduous incisors themselves mere fractured, but they were apparently retained for some time. When the permanent lower right central incisor first began to erupt, the parents noticed that the tooth was developing in a “flattened position.”
Fig. I.-An
intraoral
roentgenogram. Note the bend of the tooth and the more opaque structure within the tooth that resembles a miniature tooth.
Clinical examination showed the crown to be erupting labially and in an almost horizontal position. The incisal edge protruded into the lower lip area when the mouth was in a closed, relaxed position. Incisal contact or function with the maxillary incisors when the jaws were in centric occlusion was not possible. The patient stated that the tooth seemed to be loose periodically and also that it was sensitive to cold beverages. On several occasions, because of the abnormal location of the incisal edge, the child injured her lower lip during play. Intraoral roentgenograms suggested a bend of the tooth at the cervical area of the crown (Fig. 1). Roentgenographically, the tooth also resembled a dens in dente. Because of the extreme anterior crowding, sensitivity, lack of function, and the fact that a crown preparation could not be accomplished without an unusual root canal procedure, the tooth was removed. The direction of force of the forceps was in line with the root and not the crown. Upon extraction, the incisor was noted to be boot-shaped, the crown apparently joining the root at almost a right angle (Fig. 2). Microscopic examination revealed that the cervical point of the dentinoenamel junction extended into the center of the coronal pulp (Fig. 3). A large projection of osteodentine
Volume Number
Ii
I I)
DILACERATION
Fig. 2.-The specimen the dentinoenamel junction chamber. A large projection (Magnification, x9, reduced
OF MANDIBULAR
PERUANF,NT
TNCISOR
1251
The cervical point of is obviously boot-shaped in appearance. is located within the approximat? center of the coronal pulp of osteodentine extends apically from the point of penetration. 1/.)
Fig. 3.-A higher-power view of the specimen shown in Fig. 2. Point a originally joined Remaining enamel matrix is seen at e. The dotted line represents the division point b. between dentine formed before and after the traumatic episode. The delineation resembles a neonatal line as seen in deciduous teeth. Points r locate foci of resorption where oAont.oclnsts were found. (Magnification, X20; reduced %.)
1252
GLENN
AND
STANLEY
OS.. O.M. & O.P. Octolrer, 1961)
reached apically from this point (Figs. 2 and 3). As illustrated in Fig. 2, point a originally joined point b. The sliver at point e is all that remained of the enamel matrix after dccalcification. Except for the central projection of irregular dentine within the pulp, the remaining dentinc was primary in character. However, thcrc could be seen a division in the primary dentine of the crown (Figs. 2 and 3) which probably represented the amounts of dentine formation completed before and after the timo of injury. This delineation gives the appearance of a neonatal line, as seen in deciduous teeth. The areas at points r revealed foci of resorption due to odontoclastie activity. DISCUSSION
According to Ellis,4 the defect will appear at the junction of the crown and root or within the root of the tooth itself, depending upon the stage or age of development of the tooth at the time of the disturbance. In the case just described the almost 90 degree bend of the crown to the root gives interesting support to that premise. At the time of injury the tooth bud was bent in such a fashion that the cervical point of the dentinoenamel junction was evidently forced into the center of the pulp chamber at the cervical level. The pulp tissue, in response to the presence of this structure, laid down a large projection of osteodentine within the pulp chamber which created the illusion in the roentgenogram of a dens in dente. REFERENCES
1. Thoma,
Kurt H.: Oral Pathology, ed. 4, St. Louis, 1954, The C. V. Mosby Company, pp. 79-81. 2. Glenn, F.: Oral Injuries in Children, a Census Study, Clin. Proc. Child. Hosp., Wash. 13: 197, 1957. 3. Sauntone, P.: Cited by Thorna+ pp. 79-80. and Treatment of Injuries to the Teeth of Children, ed. 3, 4. Ellis, R.: The Classification Chicago, 1952, The Year Book Publishers, Inc., pp. 231-236.