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

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

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 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

Etiologies of the molar teeth impaction are cyst, supernumerary teeth, ankylosis by replacement by replacement resorption, abnormal eruptive path. improper orthodontic treatment, etc. If the impacted teeth were untreated, the sequallae was as follows : loss of occlusal function, loss of permanent tooth, extrusion of opposite tooth, root resorption of adjacent teeth. The most important factor solution of impacted teeth is treatment timing & proper application of orthodontic forces.
Ankylosis ; Molar* ; Root Resorption ; Tooth* ; Tooth, Impacted ; Tooth, Supernumerary

OBJECTIVETo investigate the relationship between apical root resorption and orthodontic tooth movement in growing subjects.

METHODS58 growing subjects were collected randomly into the study sample and another 40 non-treated cases were used as control. The apical resoption of the upper central incisors was measured on periapical film and the incisor displacement was measured on lateral cephalogram. Using multiple linear regression analysis to examine the relationship between root resoption and the displacement of the upper incisor apex in each of four direction (retraction, advancement, intrusion and extrusion).

RESULTSThe statistically significant negative association were found between resorption and both intrusion (P < 0.001) and extrusion (P < 0.05), but no significant association was found between resorption and both retraction and advancement. The regression analysis implied an average of 2.29 mm resorption in the absence of apical displacement.

CONCLUSIONSThe likelihood that the magnitude of displacement of the incisor root is positively associated with root resoption in the population of treated growing subjects is very small.

This experiment was performed to study the effect of prostaglandin E2 on tooth movement and root resorption in orthodontically treated cats. Twenty five cats were divided into five groups and closed coil springs delivered 80gm were stretched between upper canine and 3rd premolar. 10microgram of PGE2 was injected locally in the submucosal area of the upper right canine, while the left side served as a control and was injected saline 0.1ml. The distance between canine tip and central cusp tip of the 3rd premolar was measured. Scanning electron photomicrographs were made of the coronal half of the distal root surface of canines and cemental craterings were observed and quantified using point-counting volumetry. Data were analyzed by 2-way ANOVA and paired t-test. The results were as follows: 1. The rate of tooth movement of the PGE2 side was increased, particularly at 1 day, compared with the control side. 2. The rate of tooth movement was minimum from 7 days to 10 days. 3. The resorption of root surface of the PGE2 side was decreased from 4 days to 10 days, compared with the control side.
Animals ; Bicuspid ; Cats* ; Dinoprostone* ; Root Resorption* ; Tooth Movement* ; Tooth*

Treatment mechanics should be individualized to be suitable for each patient`s personal teeth and anatomic environment to get a best treatment result with the least harmful effects to teeth and surrounding tissues. Especially, the change of biomechanical reaction associated with that of the centers of resistance of teeth should be considered when crown-to-root ratio changed due to problematic root resorption and/or periodontal disease during adult orthodontic treatment. At the present study in order to investigate patterns of initial displacements of anterior teeth under certain orthodontic force when crown-to-root ratio changed in not only normal periodontal condition but also abnormal periodontal and/or teeth condition, the changes of the centers of resistance for maxillary and mandibular 6 anterior teeth as a segment were studied using the laser reflection technique, the lever&pulley force applicator and the photodetector with these quantified variables reducing alveolar bone 2mm by 2mm for each of maxillary 6 anterior teeth until the total amount of 8mm and root 2mm for each of mandibular 6 anterior ones until the total amount of 6mm. The results were as follows: 1. Under unreduced condition, the center of resistance during initial displacement of maxillary 6 anterior teeth was located at the point of about 42.4% apically from cemento-enamel junction(CEJ) of the averaged tooth of them and kept shifting to about 76.7% with alveolar bone reduction. 2. The distance from the averaged alveolar crest level of maxillary 6 anterior teeth to the center of resistance for the averaged tooth of them kept decreasing with alveolar bone reduction, but the ratio to length of the averaged root embedded in the alveolar bone was stable at around 33% regardless of that. 3. Under unreduced condition, the center of resistance during initial displacement of mandibular 6 anterior teeth was located at the point of about 43% apically from CEJ of the averaged tooth of them and this ratio kept increasing tc about 54% with root reduction. Bur the distance from CEJ to the center of resistance decreased from around 5.3mm to around 3.3mm, that is to say, the center of resistance kept shifting toward CEJ with the shortening of root length. 4. A unit reduction of alveolar bone had greater effects on the change of the centers of resistance than that of root did during initial phase of each reduction. But both of them had similar effects at the middle region of whole length of the averaged root.
Adult ; Humans ; Mechanics ; Periodontal Diseases ; Root Resorption ; Tooth Cervix ; Tooth*