• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.137-144
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• 2009

The aim of this study was to investigate the shapes and diameters of the physiological foramen and anatomy of the root canal at 3mm from apex in mandibular first molars. Sixty mandibular first molars were randomly selected. The apical anatomy of 60 mandibular first molars was investigated by means of a stereo microscope (60x magnification). The results were as follows; 1. There was a high percentage of two physiological foramina in mesial (61.67%) and one foramen in distal(71.66%) roots of mandibular first molars. 2. There was a high frequency of accessory foramina in mesial roots with one foramen (26.07%). 3. The diameters of physiological foramen was as follows: - 0.329mm in single mesial foramen - 0.266mm in mesiobuccal foramen and 0.246mm in mesiolingual foramen - 0.375mm in single distal foramen - 0.291mm in distobuccal foramen and 0.237mm in distolingual foramen 4. The most common physiological foramen shape was oval (69.93%). 5. The incidence of isthmus in mesial root at 3mm from apex was 55%. The 3mm-sections contained a complete isthmus 31.66% and a partial isthmus 23.34%. 6. 3mm from the apex, the most common canal shape was oval (50.64%). Knowledge of the apical anatomy of mandibular first molar would be necessary for success of surgical and nonsurgical endodontic treatment.

• The korean journal of orthodontics
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• v.34 no.3 s.104
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• pp.241-251
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• 2004

Previous studies have focused on the causes of root resorption after orthodontic treatment and treatment methods to reduce this phenomenon, and have been mainly associated with developed, mature roots. As parents become increasingly interested in their children's' dentition, orthodontists are performing fixed orthodontic treatment on patients of less than 10 years and before the completion of the immature root. Thus, the author evaluated the changes of root length and root form of maxillary immature incisors after orthodontic treatment, compared with those of mature teeth, and investigated the correlation according to gender, treatment duration, and displacement of incisors. The sample consisted of an immature root group of twenty-eight persons (between 8 and 10 years old) and a mature root group of thirty-one persons (between 11 and 15 years old). The crown and root length of the maxillary four incisors were measured with a periapical radiograph, changes in root length and crown-root ratio were calculated, and root form was classified according to a scoring system. The results were as follows. 1. The development of immature roots was not affected by orthodontic treatment and mostly showed normal root length and apical form. 2. Root length of immature teeth was sustained or became shorter, partially in long treatment duration or with open bite patients. Even though the teeth reached their normal root length, they demonstrated a blunt form. 3. Most of the mature roots showed mild resorption, and the form of mature roots was more blunt than the developed form of the immature roots (p<0.05). 4. The developed form of the immature roots was statistically related to treatment duration, while the form of the mature roots was significantly related to the displacement of incisors (p<0.05). 5. In contrast, other variables such as gender, classification of malocclusion, changes in overbite, and changes of U1 to SN showed no correlation with the root resorption of both groups.

• The korean journal of orthodontics
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• v.41 no.3
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• pp.174-183
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• 2011

Objective: Orthodontically induced root resorption (OIRR) involves partial loss of cementum and dentin of teeth caused by routine orthodontic treatment. It decreases root length and influences the function of affected teeth. In this study, the treatment and patient factors causing apical root resorption in Koreans were determined. The observed factors were extraction, gender, age, displacement of root apex, total treatment period, total teeth length, and shape of the root. Methods: The records of 137 patients treated with full, fixed edgewise appliances were obtained from the Department of Orthodontics, Dankook University Dental Hospital, from November 2007 to December 2008. Periapical radiographs of the maxillary central incisors and cephalometric radiographs of each patient were used to assess apical root resorption and type of tooth movement. Results: The mean amount of resorption was $1.62{\pm}1.58mm$. The amount of resorption in the extraction and non-extraction groups was $2.10{\pm}1.64mm$ and $1.18{\pm}1.39mm$, respectively. The amount of root resorption increased with the total tooth length. Severe root resorption (> 4 mm) was related to abnormal root shape (blunt, pointed, or eroded). Conclusions: The variables significantly related to OIRR were extraction, initial tooth length, and root shape.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.4
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• pp.524-534
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• 2000

Deciduous teeth can be extracted for two reasons, one due to the physiologic resorption and the other by the inflammation at the apex after traumatic injury. Physiologic resorption may be different from pathologic resorption in timing and mechanism. Therefore we resumed the different features of physiologic and pathologic resorption root surfaces. Many previous studies showed micromorphology of resorbed surface of roots of deciduous teeth. But, few studies compared physiological and pathological root resorption surfaces. In this study, we carefully observed microscopic morphologies of those two different root surfaces by scanning electron microscope and histologic features by light microscope. The resultant differences between physiologic and pathologic resorption surfaces of deciduous teeth were as follows: 1. The morphology of pathologic resorption lacunae due to inflammation varied in size and shape with irregular boundaries compared with the physiologic areas from scanning electron microscope observations. 2. From light microscope observations, several large resorption fossae containing numerous resorption lacunae were found, whereas the resorption lacunae were irregular in shape with pathologic resorption surface. 3. Numerous multinucleated giant cells were closely attached to the physiologic resorption lacunae, whereas several kinds of mesenchymal cells with numerous inflammatory cells were found in the areas adjacent to the pathologic resorption surface. 4. Light microscope findings showed that compensating cementum formation took place along some of the areas of inflammatory dentinal resorption. In conclusion, several morphological differences were present between physiologic and pathologic root resorption surfaces of human deciduous teeth. The future studies should include cytochemistry to clarify the cellular roles in resorption process observations of pulpal surfaces of coronal and radicular dentin to and the changes that occur in each phase of human deciduous tooth resorption.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.87-92
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• 2016

The purpose of this clinical report was to show anatomical variations in permanent maxillary second molar using computed tomography (CT). This case report describes the application of CT to detect the unusual root anatomy of maxillary second molar with 2 separate palatal roots for successful endodontic treatment procedures. The use of cone beam computed tomography (CBCT) can overcome the limitation of the periapical standard radiography caused by the overlap of buccal and secondary palatal roots.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.172-179
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• 2015

The developmental mechanism of root formation is a complex process. Hereditary and environmental factors may affect the morphology of the developing root. A total of 12 cases was presented with permanent first molars with abberant root morphology. Clinically, these teeth appeared as a normal crown. However, radiographically, the root was slender, twisted and characterized by irregular lengths. In addition, root trunk length was shorter and pulp chamber was obliterated. In these cases, periapical radiolucency and loss of lamina dura were often observed. In 6 cases, an abnormal root of the primary second molars were also present, as well as root malformation of permanent first molars. In 3 cases, permanent central incisors also had a dysmorphic crown. These cases almost all had medical history, such as premature birth, brain infection or congenital heart disease in infants. The present paper describes cases of permanent first molars with an abnormal root that are rarely reported in literature. This case may intensify the variation in the permanent first molar and is intended to reinforce the clinician's awareness of rare morphology of the roots.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.4
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• pp.437-448
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• 2021

The purpose of this study is to analyze morphological characteristics of maxillary primary molar's root and root canal. 268 children aged 3 - 7 years (175 boys, 93 girls) who had CBCT (152 children) and 3D CT (116 children) taken in Seoul National University Dental Hospital from January 2006 to April 2020 were included. The number of roots and root canals were analyzed in 1002 teeth without any root resorption or periapical pathologies. Curvature, angulation, length of root and root canal, as well as cross-sectional shapes of the root canal were analyzed in 218 teeth. By using Mimics and 3-Matics software, volume, surface area, and volume ratio of root canal was analyzed in 48 teeth. More than half of maxillary primary molars have 3 roots and 3 root canals. The degree of symmetry of root canal type was about 0.63 (Cohen's kappa coefficient). The most frequent shape of roots and canals was linear in 1^st primary molars and curved in 2^nd primary molars. Angulation, length of root and root canals was the largest on palatal roots. Most teeth showed ovoid or round shapes at apex. The largest root canal volume, surface area, volume ratio was found in the palatal roots.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.25-35
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• 2020

The purpose of this study is to evaluate the morphological characteristics of the roots and roots canals of primary molar teeth using Cone-Beam Computed Tomography (CBCT). A total of 68 CBCT images of children aged 4 - 5 years was used for this study. A total of 160 molar teeth were analyzed. Various parameters such as the number of roots and canals, length of root and root canal, and the angulation and shape of the roots were analyzed. All maxillary primary molars had 3 roots. The presence of 2 root canals in 1 root was only observed in the mesiobuccal root of maxillary primary second molars. Most mandibular primary molars had 2 roots, and most mesial roots had 2 root canals. Concerning the length of the roots, the palatal root of the maxillary primary molar was found to be longest whereas the distobuccal root was shortest. In mandibular primary molars, the mesial root was longer than the distal root. In maxillary primary molars, the palatal root had the greatest angulation whereas the distal root has the greatest in mandibular molars. The root and root canals of maxillary primary molars were more curved in shape whereas mandibular primary molars were straight.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.1
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• pp.121-130
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• 2022

Molar-incisor malformation (MIM) is a newly reported dental anomaly with molar root deformity and incisor crown defects. MIM-affected teeth may cause severe pain with no apparent tooth caries. Since the affected molars clinically appear normal, radiographs are recommended for accurate diagnosis on the first visit. Since MIM-affected patients are in mixed dentition, timely and appropriate interventions are needed to avoid unnecessary pain and complicated clinical issues. This report was written to describe two patients who had MIM in early mixed dentition and report their 2-year follow-ups.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.2
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• pp.104-111
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• 2015

Purpose: The aim of this retrospective study was to investigate the prevalence rate and types of C-shaped roots and C-shaped canal in maxillary molars by analyzing cone-beam computed tomography (CBCT) in a Korean population. Materials and Methods: Total of 357 CBCT images of maxillary molars (186 first molar, 171 second molar) were evaluated by two Endodontic specialists. Results: Eight types of C-shaped roots and 5 types of C-shaped canals were founded, the prevalence rate of C-shaped roots and canals were 21.0% and 5.3% respectively. Conclusion: These anatomical variations were more frequent in second molars than the first molars. Clinicians should have anatomical knowledge about various types of C-shaped root and root canal for successful root canal therapy.