Case report
Continuing root formation following apexification treatment Yang S-F, Yang Z-P, Chang K-W. Continuing root formation following apexification treatment. Endod Dent Traumatol 1990; 6: 232-235. Abstract -^ A case report is presented in which continuing root formation occurred in an immature mandibular second premolar after calcium hydroxide apexification treatment. An apical hard tissue barrier was accompanied by a separate disto-apically growing root 18 months posttreatment. Histologic evaluation of the root revealed immature hard tissue mixed with calcium hydroxide, connective tissue and bone, apically in the original root canal. In the separate new formed part of the root, pulp tissue, odontoblasts, predentin, cementum and an apical foraman could be identified.
In immature teeth in which the pulps are necrotic or are severely infiamed, apexification procedures are used for inducing root end closure, and calcium hydroxide is the preferred medicament used in these procedures. The nature of the root end closure barrier suggested in histologic studies may be consistent with cementum (1-5), bone (6), dentin (7), or osteodentin (8). Compared with apical hard barrier formation, continued root formation after apexification is rare. Some cases have been reported by Stewart (9), Heithersay (7) and Andreasen (10), but few of them were documented histologically. This paper is a clinical and histological report of an immature mandibular second premolar which not only had the formation of an apical hard tissue barrier but continued root formation after apexification.
Shue-Fen Yang, Zu-Pyn Yang and Kuo-Wei Chang School of Dentistry, National Yang-Ming Medical College, Veterans General Hospital, Taipei, Taiwan, R.O.C.
Key words: endodontic therapy; calcium hydroxide; apexigenesis; root formation. Dr. Shue-Fen Yang, Dental Department, Veterans General Hospital, Taipei, Taiwan, 11217, R.O.C. Accepted for publication April 9, 1990.
apex and a poor crown-root ratio (Fig. 1). The diagnosis was symptomatic apical periodontitis. Anesthesia of the left mandibular posterior quadrant was obtained with lidocaine and 1/100,000 epinephrine and access to the pulpal lumen prepared. Blood and a small amount of purulent fluid
Case report An 8-year-old boy who had suffered spontaneous pain for two days was referred to our department for evaluation and possible endodontic treatment of his lower left second premolar. Clinical evaluation disclosed that the patient was wearing a lingual holding arch appliance and his newly erupted lower left second premolar with a fractured central cusp was hyperreactive to percussion. A radiograph revealed that the tooh had a thin root dentin with an incompletely developed 232
Fig. 1. Radiograph of painful mandibular second premolar. The patient was wearing lingual holding arch appliance. Notice the thin root dentin, a large pulp cavity, an incompletely developed apex and the poor crown-root ratio.
Root formation following apexification
Fig. 2. Radiograph of the tooth taken one month following beginning of apexification treatment. The canal space is filled with calcium hydroxide. No new root tip is seen at this time.
Fig. 4. Pre-extraction radiograph of the tooth taken 18 months following beginning of the apexification treatment. An apical tissue barrier (white arrow) has formed in the root canal. A new root tip (black arrows) has developed about 2 mm disto-apically to the original root end.
flooded the opened pulp space. After completing the chemomechanical preparation, the canal was filled with calcium hydroxide-distilled water paste and the access opening was closed with an intermediate restorative material. The patient was recalled every 3 months for evaluation and when necessary to change calcium hydroxide (Figs. 2, 3). At the 18 month recall, the patient reported that the tooth had fractured one week previously. Radio-
Fig. 3. Radiograph of the tooth taken 12 months following beginning of apexification treatment. The calcium hydroxide in the canal space is washed out. Radiopaque tissue (arrow) has formed apically to the original root end.
Fig. 5. Histologic section cut longitudinally through the root tip specimen. There is a mixture of immature hard tissue, calcium hydroxide and bone in the original root canal above the two arrows. The new rot tip is seen in the apical part below the two arrows. The blank space (S) seen between the two portions is due to tearing during the histologic preparation ( H & E stain; original magnification x 25).
233
S-F Yang et al. graphic examination showed a subgingival horizontal root fracture and formation of a hard tissue barrier apically at the original root end. Radiopaque tissue appeared in a 2 mm disto-apical position to the original root. It was about 4 mm in length and similar in shape to a root tip (Fig. 4). During extraction, the coronal part of the root was abandoned because it fractured into several small pieces. The apical part was recovered, fixed, sectioned longitudinally and stained with hematoxylin and eosin for histologic evaluation. The microscopic examination showed that a new root tip had formed (Figs. 5, 6). Apically in the original root canal, there was immature hard tissue mixed with calcium hydroxide, connective tissue and bone (Figs. 5, 7). The blank space seen in the specimen was due to tearing during the histologic preparation (Fig. 5). In the new root tip formed separately from the root, pulp tissue, an odontoblastic layer, predentin, dentin, cementum and an apical foramen could be identified (Figs. 6, 8).
Discussion Four types of apical development after successful apexification have been described by Frank (11). In
Fig. 7. A, coronal part of the specimen. B, enlargement of the area near the arrow seen in A. Notice the immature hard tissue (I) mixed with calcium hydroxide (small dark zone C), and connective tissue (CT) ( H & E stain; original magnification x250).
Fig. 6. A, apical part of the specimen. B, enlargement of the area near the arrow seen in A. The cemento-dentinal junction including cementum (C) and dentin (D) may be identified (H & E stain; original magnification x 100).
234
our histologic sections, the immature hard tissue consisted partly of a hard apical barrier of the original root appearing like osteodentin, immature cementum, or immature bone. This is in agreement with other reports (1-6, 8). An unusual finding with our patient was that a new root tip had formed disto-apically to the original root end following apexification. The new root tip was composed of normal pulp, predentin, dentin, and cementum. Normally Hertwig's epithelial root sheath determines the number, size and shape of the roots. It is believed that the apex may develop in a normal manner if Hertwig's root sheath has not been damaged after apexification procedures (12). The patient's tooth with the infiamed pulp tissues evident upon the emergency opening of the chamber might have preserved the vitality of Hertwig's root sheath throughout the apexification treatment. A strong tendency of the teeth to drift mesially even before they appear in the oral cavity is a common finding. This phenomenon may explain why the new root tip was located distoapically to the original root.
Root formation following apexification an additional new root tip developed after long term treatment with calcium hydroxide including elimination of the root canal infection. The vitality of the Hertwig's root sheath and proper treatment may play important roles in such an occurrence.
References 1.
2.
3.
4.
5. 6.
7.
8. Fig. 8. A, section from the apical part of the root tip specimen. B, enlargement of the area near the arrow seen in A. Observe pulp tissue (PT), odontoblast layer (O), predentin (P) and dentin (D) ( H & E stain; original magnification x400).
9. 10.
11.
We have shown that in an immature mandibular premolar an apical hard tissue barrier formed and
12.
JC, VAN HASSEL HJ. Experimental root apexification in primates. Oral Surg Oral Med Oral Pathol 1971; 31: 409-15. HAM JW, PATTERSON SS, MITCHELL DF. Induced apical closure of immature pulpless teeth in monkeys. Orat Surg Oral Med Oral Pathol 1972; 33: 438-49. CVEK M , SUNDSTROM B. Treatment of nonvdtal permanent incisors with calcium hydroxide. V. Histologic appearance of roentgenographically demonstrable apical closure of immature roots. Odontol Revy 1974; 25: 379-92. KLEIN SH, LEVY BA. Histologic evaluation of induced apical closure of a human pulpless tooth. Oral Surg Oral Med Orat Pathol 1974, 38: 954-9. PiEKOFF MD, TROTT JR. Apexification: Report of a case. J Endod 1976; 2: 182-5. ToRNECK CD, SMITH J, GRINDALL P. Biologic effects of endodontic procedures on developing incisor teeth. H. Effect of pulp injury and oral contamination. Oral Surg Oral Med Orat Pathol 1973; 35: 378-88. HEITHERSAY G . Stimulation of root formation in incompletely developed pulpless teeth. Oral Surg Oral Med Orat Pathol 1970; 29: 620-30. DYLEWSKIJJ. Apical closure of nonvital teeth. Oral Surg Orat Med Oral Pathol 1971; 52; 82-9. STEWART G G . Dent Clin North Am 1967; / / ; 711-22. ANDREASEN J O . Traumatic injuries of the teeth. 2nd ed. Copenhagen: Munksgaard International publishers, 1988: 348. FRANK AL. Therapy for the divergent pulpless tooth by continued apical formation. J Am Dent Assoc 1966; 72: 82-6. SELTZER S. Endodontology. 2nd ed. Philadelphia: Lea & Febiger, 1988: 5. STEINER
235
Continuing root formation following apexification treatment Yang S-F, Yang Z-P, Chang K-W. Continuing root formation following apexification treatment. Endod Dent Traumatol 1990; 6: 232-235. Abstract -^ A case report is presented in which continuing root formation occurred in an immature mandibular second premolar after calcium hydroxide apexification treatment. An apical hard tissue barrier was accompanied by a separate disto-apically growing root 18 months posttreatment. Histologic evaluation of the root revealed immature hard tissue mixed with calcium hydroxide, connective tissue and bone, apically in the original root canal. In the separate new formed part of the root, pulp tissue, odontoblasts, predentin, cementum and an apical foraman could be identified.
In immature teeth in which the pulps are necrotic or are severely infiamed, apexification procedures are used for inducing root end closure, and calcium hydroxide is the preferred medicament used in these procedures. The nature of the root end closure barrier suggested in histologic studies may be consistent with cementum (1-5), bone (6), dentin (7), or osteodentin (8). Compared with apical hard barrier formation, continued root formation after apexification is rare. Some cases have been reported by Stewart (9), Heithersay (7) and Andreasen (10), but few of them were documented histologically. This paper is a clinical and histological report of an immature mandibular second premolar which not only had the formation of an apical hard tissue barrier but continued root formation after apexification.
Shue-Fen Yang, Zu-Pyn Yang and Kuo-Wei Chang School of Dentistry, National Yang-Ming Medical College, Veterans General Hospital, Taipei, Taiwan, R.O.C.
Key words: endodontic therapy; calcium hydroxide; apexigenesis; root formation. Dr. Shue-Fen Yang, Dental Department, Veterans General Hospital, Taipei, Taiwan, 11217, R.O.C. Accepted for publication April 9, 1990.
apex and a poor crown-root ratio (Fig. 1). The diagnosis was symptomatic apical periodontitis. Anesthesia of the left mandibular posterior quadrant was obtained with lidocaine and 1/100,000 epinephrine and access to the pulpal lumen prepared. Blood and a small amount of purulent fluid
Case report An 8-year-old boy who had suffered spontaneous pain for two days was referred to our department for evaluation and possible endodontic treatment of his lower left second premolar. Clinical evaluation disclosed that the patient was wearing a lingual holding arch appliance and his newly erupted lower left second premolar with a fractured central cusp was hyperreactive to percussion. A radiograph revealed that the tooh had a thin root dentin with an incompletely developed 232
Fig. 1. Radiograph of painful mandibular second premolar. The patient was wearing lingual holding arch appliance. Notice the thin root dentin, a large pulp cavity, an incompletely developed apex and the poor crown-root ratio.
Root formation following apexification
Fig. 2. Radiograph of the tooth taken one month following beginning of apexification treatment. The canal space is filled with calcium hydroxide. No new root tip is seen at this time.
Fig. 4. Pre-extraction radiograph of the tooth taken 18 months following beginning of the apexification treatment. An apical tissue barrier (white arrow) has formed in the root canal. A new root tip (black arrows) has developed about 2 mm disto-apically to the original root end.
flooded the opened pulp space. After completing the chemomechanical preparation, the canal was filled with calcium hydroxide-distilled water paste and the access opening was closed with an intermediate restorative material. The patient was recalled every 3 months for evaluation and when necessary to change calcium hydroxide (Figs. 2, 3). At the 18 month recall, the patient reported that the tooth had fractured one week previously. Radio-
Fig. 3. Radiograph of the tooth taken 12 months following beginning of apexification treatment. The calcium hydroxide in the canal space is washed out. Radiopaque tissue (arrow) has formed apically to the original root end.
Fig. 5. Histologic section cut longitudinally through the root tip specimen. There is a mixture of immature hard tissue, calcium hydroxide and bone in the original root canal above the two arrows. The new rot tip is seen in the apical part below the two arrows. The blank space (S) seen between the two portions is due to tearing during the histologic preparation ( H & E stain; original magnification x 25).
233
S-F Yang et al. graphic examination showed a subgingival horizontal root fracture and formation of a hard tissue barrier apically at the original root end. Radiopaque tissue appeared in a 2 mm disto-apical position to the original root. It was about 4 mm in length and similar in shape to a root tip (Fig. 4). During extraction, the coronal part of the root was abandoned because it fractured into several small pieces. The apical part was recovered, fixed, sectioned longitudinally and stained with hematoxylin and eosin for histologic evaluation. The microscopic examination showed that a new root tip had formed (Figs. 5, 6). Apically in the original root canal, there was immature hard tissue mixed with calcium hydroxide, connective tissue and bone (Figs. 5, 7). The blank space seen in the specimen was due to tearing during the histologic preparation (Fig. 5). In the new root tip formed separately from the root, pulp tissue, an odontoblastic layer, predentin, dentin, cementum and an apical foramen could be identified (Figs. 6, 8).
Discussion Four types of apical development after successful apexification have been described by Frank (11). In
Fig. 7. A, coronal part of the specimen. B, enlargement of the area near the arrow seen in A. Notice the immature hard tissue (I) mixed with calcium hydroxide (small dark zone C), and connective tissue (CT) ( H & E stain; original magnification x250).
Fig. 6. A, apical part of the specimen. B, enlargement of the area near the arrow seen in A. The cemento-dentinal junction including cementum (C) and dentin (D) may be identified (H & E stain; original magnification x 100).
234
our histologic sections, the immature hard tissue consisted partly of a hard apical barrier of the original root appearing like osteodentin, immature cementum, or immature bone. This is in agreement with other reports (1-6, 8). An unusual finding with our patient was that a new root tip had formed disto-apically to the original root end following apexification. The new root tip was composed of normal pulp, predentin, dentin, and cementum. Normally Hertwig's epithelial root sheath determines the number, size and shape of the roots. It is believed that the apex may develop in a normal manner if Hertwig's root sheath has not been damaged after apexification procedures (12). The patient's tooth with the infiamed pulp tissues evident upon the emergency opening of the chamber might have preserved the vitality of Hertwig's root sheath throughout the apexification treatment. A strong tendency of the teeth to drift mesially even before they appear in the oral cavity is a common finding. This phenomenon may explain why the new root tip was located distoapically to the original root.
Root formation following apexification an additional new root tip developed after long term treatment with calcium hydroxide including elimination of the root canal infection. The vitality of the Hertwig's root sheath and proper treatment may play important roles in such an occurrence.
References 1.
2.
3.
4.
5. 6.
7.
8. Fig. 8. A, section from the apical part of the root tip specimen. B, enlargement of the area near the arrow seen in A. Observe pulp tissue (PT), odontoblast layer (O), predentin (P) and dentin (D) ( H & E stain; original magnification x400).
9. 10.
11.
We have shown that in an immature mandibular premolar an apical hard tissue barrier formed and
12.
JC, VAN HASSEL HJ. Experimental root apexification in primates. Oral Surg Oral Med Oral Pathol 1971; 31: 409-15. HAM JW, PATTERSON SS, MITCHELL DF. Induced apical closure of immature pulpless teeth in monkeys. Orat Surg Oral Med Oral Pathol 1972; 33: 438-49. CVEK M , SUNDSTROM B. Treatment of nonvdtal permanent incisors with calcium hydroxide. V. Histologic appearance of roentgenographically demonstrable apical closure of immature roots. Odontol Revy 1974; 25: 379-92. KLEIN SH, LEVY BA. Histologic evaluation of induced apical closure of a human pulpless tooth. Oral Surg Oral Med Orat Pathol 1974, 38: 954-9. PiEKOFF MD, TROTT JR. Apexification: Report of a case. J Endod 1976; 2: 182-5. ToRNECK CD, SMITH J, GRINDALL P. Biologic effects of endodontic procedures on developing incisor teeth. H. Effect of pulp injury and oral contamination. Oral Surg Oral Med Orat Pathol 1973; 35: 378-88. HEITHERSAY G . Stimulation of root formation in incompletely developed pulpless teeth. Oral Surg Oral Med Orat Pathol 1970; 29: 620-30. DYLEWSKIJJ. Apical closure of nonvital teeth. Oral Surg Orat Med Oral Pathol 1971; 52; 82-9. STEWART G G . Dent Clin North Am 1967; / / ; 711-22. ANDREASEN J O . Traumatic injuries of the teeth. 2nd ed. Copenhagen: Munksgaard International publishers, 1988: 348. FRANK AL. Therapy for the divergent pulpless tooth by continued apical formation. J Am Dent Assoc 1966; 72: 82-6. SELTZER S. Endodontology. 2nd ed. Philadelphia: Lea & Febiger, 1988: 5. STEINER
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