The purpose of this study was to find the distribution and measurement of compressive and tensile stress when intrusi- on arch wire is forced engage with upper canine and to analysis stress at each section through FEM. And we compare compressive and tensile ratio at each section. The results were as follows. 1. At FA point and cemento-enamel junction of upper canine, compressive and tensile force ratio is about the same. 2. At apex, compressive force is the four times as tensile force. ; In intrusion, we show root resorption at apex. 3. At Cemento-enamel junction, the compressive and tensile force show the maximun value except FA point.
Root Resorption

Humans ; Root Resorption

Inflammatory external root resorption (IERR) refers to the pathological process of dissolving the hard tissue on the outer surface of the tooth root by the body's own immune system under the stimulation of various physical and chemical factors such as infection, stress, trauma and orthodontic treatment. Severe IERR can lead to endodontic and periodontal diseases, and even the loss of teeth. Therefore, understanding the etiology and the pathogenic mechanism of IERR are of importance in its prevention and treatment. This article will review the etiology and the regulation mechanisms of IERR.
Dental Cementum ; Humans ; Root Resorption ; Tooth Root

Internal root resorption is a pathologic phenomenon with a characterization of the intraradicular dentin destruction due to the abnormal activities of odontoclasts. With its insidious pathology, internal root resorption can progress to a great extent before its clinical detection. The etiology and natural history of internal root resorption are uncertain and the associated key molecular pathogenesis have not been understood completely. The resorption is usually initiated by a stimulus with the loss of the protective predentin and progressed by the continuous stimuli of pulp infection. Various factors including trauma, chronic inflammation of the pulp, pulpotomy and tooth transplantation have been proposed for the occurrence of internal root resorption. The present paper reviews the etiology and pathogenesis of internal root resorption and provides guidance for the early intervention in the clinical practice.
Humans ; Pulpotomy ; Root Resorption/etiology*

Tooth resorption is an idiopathic destructive disease of dental hard tissues. The etiology and pathogenesis remain obscure. It has various manifestations and can be commonly classified as internal tooth resorption and external root resorption on the basis of the resorptive lesion sites. There have been many attempts to make further classification based upon the pathological manifestations in recent years. Radiographic examination is an effective tool to assist in the diagnosis. There are few systematic researches on tooth resorption worldwide, most of which are case reports. This review elaborates on the research progress of tooth resorption from aspects of pathogenesis and classification.
Humans ; Root Resorption/diagnostic imaging* ; Tooth Resorption/diagnostic imaging*

The purpose of this study was to investigate the root resorption pattern in incisors in dog under intrusive orthodontic loadings of various magnitude and duration. Intrusive forces were generated by closed coil springs. Force magnitudes were 15-30gm, 50-60gm and 80-110gm. Durations were continuous and intermittent. Intermittent duration was applied at intervals of 12 hours. The readjustment of the force was done every 4 days. The forces were maintained for 30 days. All specimens were decalfied, embedded in paraffin and stained with hematoxylin-eosin stain. Observations were made with light microscope. The following results were obtained; 1. The continuity of root surface was ceased in all, except intermittent forced teeth with 25gm. 2. The root resorptions, cementoclasts and cemental lacunae, were increased around periapical regions and the destructive scope of bone was deeply extended as the exerted orthodontic forces increased. 3. It was inspected that, under the same forces, root resorption and bone destruction were more deeply appeared in the continuously forced teeth than the intermittently forced ones. 4. All of the alveolar bone, showed direct and undermining bone resorptions.
Animals ; Bone Resorption ; Dogs* ; Incisor* ; Osteoclasts ; Paraffin ; Root Resorption* ; Tooth

The purpose of this study was to evaluate root resorption and alveolar bone resorption pattern by jiggling movement. adult cats were divided into 4 groups (6, 12, 18, 24 days). ln test side, mesio-distal jiggling force was applied in right maxillary 1st premolar in 3 days cycle. ln control side, mesial force was applied in left maxillary 1st premolar, Radiographic and histologic observation were formed in 6, 12, 18, 24 days after force application. The results were as follow: Alveolar bone resorption was more severe by jiggling force than by unidirectional force. Root resorption pattern was not different between jiggling force and unidirectional force. Combined pattern of bone resorption and new bone formation appeared in jiggling group. New bone formation began to appear at periapical area of jiggling group after 24 days, because alveolar bone resorption was severe and extrusion resulted.
Adult ; Animals ; Bicuspid* ; Bone Resorption* ; Cats* ; Humans ; Osteogenesis ; Root Resorption*

The purpose of this study was to obtain information on the clinical and radiographic features of the odontomas in the jaws. For this study, the authors examined and analyzed the clinical records and radiographs of 119 patients who had lesion of odontoma diagnosed by clinical and radiographic examinations. The obtained results were as follows ; 1. Odontoma occurred the most frequently in the 2nd decade(45.4%) and occurred more frequently in males(60.5%) than in females(39.5%). 2. The most common clinical symptom was the delayed eruption of the teeth(34.2%). 3. The type of lesions was mainly observed as compound odontoma(80.8%), and internal pattern of the complex odontoma was unevenly radiopaque(73.9%). 4. The compound odontoma frequently occurred in anterior portion of the maxilla(57.7%) and mandible(30.9%), and complex odontoma frequently occurred in anterior portion of maxilla(34.8%) and posterior portion of mandible(30.5%). 5. The effects on adjacent teeth were impaction of teeth(71.7%) and prolonged retention of deciduous teeth(31.7%). 6. The impaction of the teeth occurred in anterior portion of maxilla(44.2%) amd mandible(19.2%), but root resorption of the adjacent teeth were not seen. 7. The boundary to adjacent structure was well-defined, the lesions appear as radiopaque mass with radiolucent rim.
Humans ; Jaw ; Odontoma* ; Root Resorption ; Tooth

The purpose of this study was to investigate the root resorption and repair pattern of human teeth under intrusive orthodontic loadings of varying magnitude and duration. 50 gms, 100 gms, 200 gms of force applied to the 96 experimental teeth with duration of 2, 5, 7, 10 weeks, after removing the arch wire and retaining during 2 and 6 weeks, experimental teeth were extracted. Results were as follows: 1. The initial resorption site was visible in the apex within 2 weeks with 50 gms, 100 gms samples. 2. The sites of resorption increased markedly with duration of the force. 3. The 50 grams samples of the all duration reveal the shallow resorption and the 100 gms samples of the all duration except 2 weeks reveal the shallow and deep resorption sites. 4. After 7 weeks with 50 gms and 100 gms, cellular cementum repair accompanied the continuing resorption. 5. 2 and 6 weeks after removing the force with 200 gms, the same cellular cementum repair accompanied with 50 gms, 100 gms samples.
Bicuspid* ; Dental Cementum ; Humans ; Root Resorption* ; Tooth

Impaction with a severely dilacerated root is seldom reported, especially in the maxillary incisor. It is probably because of the high clinical difficulty associated with bringing the dilacerated tooth into proper position, and the high chance of failure due to ankylosis, external root resorption, and root exposure after orthodontic traction. Even the successful cases may need periodontal surgery to improve the unesthetic gingival shape. However, it has previously been reported that an impacted maxillary central incisor was successfully treated by proper crown exposure and orthodontic traction. This article presents a case of an invertedly impacted maxillary right central incisor with a developing dilacerated root, which was aligned into proper position after orthodontic traction composed of two stages of a closed eruption technique.
Ankylosis ; Crowns ; Incisor* ; Root Resorption ; Tooth ; Traction