[Growth of the root and endodontic treatment of teeth during their development].
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Forty freshly single rooted teeth were selected for this study. The coronal part of teeth were decapitated and the root canals were prepared by modified step-back technique with K-flex files to size 35# at the apex, five ml of 5.25% NaOCl was used as irrigating solution. According to the dentin thickness at the mesio-distal direction of the prepared roots, roots were divided into two groups: Group (I), dentin and cementum thickness from 1.5-2 mm, and Group (II), dentin and cementum thickness 1 mm. According to the filling technique used the teeth were subdivided into four subgroups each of five teeth; Subgroup (A) single gutta-percha cone and Ketac-endo root canal sealer, Subgroup (B) lateral condensation technique with gutta-percha and Ketac-endo sealer, Subgroup (C) laterally condensed gutta-percha with Roth 801 cement and Subgroup (D) teeth left unfilled as negative controls. The prepared roots were placed into acrylic resin so that 10 mm of the root was exposed. A slowly increasing force was applied vertically using a blunt punch with 1 mm tip thickness attached to Instron testing machine. The results showed that group (I) with 1.5-2mm dentin thickness required greater force to fracture in all experimental groups, than that of group (II) with 1 mm dentin thickness. So the amount of remaining dentin thickness significantly affected the resistance to fracture of the prepared roots.
Videofluoroscopy was used as a radiographic technique to visualize a canine tooth during root canal therapy in a Siberian tiger. Videofluoroscopy was useful because the procedure was performed in a zoo setting with no access to an on-site darkroom. The fluoroscopic screen and videotape allowed for immediate viewing of the root canal system.
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Trauma to a primary mandibular central incisor resulted in a rare case of dilaceration and duplication of crown with hypercementosis of the root in the permanent successor. This tooth was extracted. This article highlights the consequences of trauma to a primary tooth for a developing permanent successor.
A case of crestal root perforation and periapical lesion in a maxillary left lateral incisor is reported. Teeth with root perforation present technical difficulties in their clinical management because of their complex defects. In the present case, surgical endodontic treatment was chosen. The apical and lateral pathology was curetted, the tooth root was resected, and a retrograde root restoration of amalgam was placed in a root-end cavity and perforation site. A 10-year follow-up clinical and radiographic examination showed an asymptomatic tooth with osseous healing proceeding.
The movement of teeth during orthodontic treatment occasionally induces undesirable root resorption. Although high collagenolytic activity has been detected in resorbing tissue of deciduous teeth, the cellular origin of collagenolytic enzymes in root-resorbing tissue caused by tooth movement has not been identified. Here, rats were subject to 7 days of experimental tooth movement to induce root resorption. In situ hybridization with digoxigenin-labelled RNA probes was performed on sections of the maxillary bone to detect the mRNAs that encode matrix metalloproteinase-1 (MMP-1) and cathepsin K in root-resorbing tissue. MMP-1 mRNA was detected in fibroblastic cells, cementoblasts and osteoblasts, but not in odontoclasts nor osteoclasts. Moreover, MMP-1 mRNA was highly expressed in some cementocytes located near odontoclasts and in many osteocytes. In contrast, cathepsin K mRNA was expressed only in odontoclasts and osteoclasts. These results suggest that MMP-1 and cathepsin K are important in root resorption during tooth movement in a mode similar to bone resorption.
This article reports the treatment of a maxillary left central incisor geminated with a supernumerary tooth. A patient having labial swelling around the maxillary incisors was referred to this hospital for diagnosis and endodontic treatment of the maxillary left central incisor. Clinical and radiographic examinations revealed a tooth having two roots and three canals. Examination of a rubber base impression of the cleaned canals showed there was neither perforation of, nor communication with, the radicular groove in the tooth.
The configuration of the root of a prospective abutment tooth has a significant influence on its potential load-bearing capacity. Dilaceration is an angulation in the root or crown. This abnormality may also affect the stability and longevity of an abutment. Finite element stress analysis was used to investigate the effect of a root dilaceration on stress distribution to the tooth and its supporting structures. A normal and a dilacerated single-rooted tooth under three loads (axial, distooblique, and mesio-oblique) were analyzed and compared. The results indicated that a dilaceration concentrates the stresses in the supporting structures and may be taken into consideration as a risk factor in abutment selection.
This study compares the image accuracy of computerized tomography (CT) with that of plain film radiography (PFR) in analyzing the 3-dimensional shape of impacted teeth suspected of being malformed. Eighteen patients with 22 malformed teeth were studied by PFR and CT. Crown shape, root shape, crown/root relationship, and tooth inclination and structure were assessed by PFR and CT. CT was found to be superior to PFR in showing the multiplanar shape of tooth crown and root, crown/root relationship, and tooth inclination (P <.001). No difference was found in the representation of tooth structures. The findings demonstrate that CT imaging is useful to diagnose and plan treatment for patients with unerupted and malformed teeth.
In the permanent tooth, physiological root resorption does not occur, but inflammatory resorption occurs due to the orthodontic force, ectopic eruption of neighboring tooth and others. In this study, the morphological and histological investigation of the root resorption of the upper permanent incisors caused by the ectopic eruption of the canine was carried out. The left central incisor and lateral incisor from a 12-year-old female were examined. The roots were resorbed almost completely, and in part the resorption extended into the enamel. The results were as follows: 1. In the resorbed dentine, two types of resorption lacuna were observed. One was in direct contact with resorption tissue and the other was repaired with cementum-like tissue. 2. In the resorption lacuna, no odontoclast was recognized. 3. The pulp tissue was normal and the internal resorption was not seen. 4. On the wall of the root canal connected with root resorption, a large amount of hard tissue was formed, and on the external surface of the root, secondary cementum was formed on the primary cementum. 5. Under the scanning electron microscope, the clear dentine tubules in the resorption lacuna, the shallow, unclear resorption lacuna with deposition of the hard tissue and the various steps between them were observed.
OBJECTIVES: To introduce a method for assessment of root growth on panoramic radiographs exemplified by a case report on an autotransplanted lower third molar. MATERIAL AND METHODS: A lower left third molar (T) with incomplete root formation was transplanted for replacement of the lower left first molar in an 18-year-old woman. T was monitored clinically and, together with its neighboring lower second molar (37) with constant root length, also radiographically by means of two panoramic radiographs (OPGs) produced 12 days and 20 months postoperatively. A method for calculation of the root length as a multiple of the crown length is introduced, using accurately reproducible landmarks defining the coronal and apical endpoints of the examined tooth in all OPGs of the series. This method minimizes error due to different magnifications within the set of radiographs. RESULTS: Using the method introduced, the root length of the constant tooth 37 varied at 2.7% within the set of OPGs, whereas it revealed a 5.6% variation when the evaluation was based on direct measurement. Based on the described method, T revealed a postoperative root growth of approximately one-third of its final length and showed clinically no pathological findings during the observation period. CONCLUSIONS: Our results indicate that with the described method root growth assessment on panoramic radiographs is more accurate than with direct measurement.
Granulation tissue which is responsible for root resorption of deciduous tooth lies between root of the deciduous tooth and its permanent tooth germ. This tissue is called "root-resorbing tissue". Its bone-resorbing activity was investigated in vitro. Bovine root-resorbing tissue was cultured in close contact with 45Ca-labeled dead calvaria of rats. Bone-resorbing activity was determined by measuring 45Ca released from labeled calvaria during culture. It was found that only the root-resorbing tissue which was rich in odontoclasts and had a good blood supply in its surface layer had bone-resorbing ability, and that bone resorption occurred only when it was placed in close contact with calvarium. The root-resorbing tissue which was poor in odontoclasts and blood vessels failed to stimulate by 25-hydroxy-vitaim D3 or heparin, but not by larger amounts of parathyroid hormone, vitamin D3, and dihydrotachysterol when added to the culture.