• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.18-29
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• 2008

The purpose of this study was to compare the polymerization shrinkage of several filling methods using strain gauges. In this study, a light-emitting diode(LED) curing unit(Elipar Freeligh2, 3M EPSE, USA) and plasma arc lamp(PAL) curing unit(Flipo, LOKKI, France) were used for curing, Filtek $Z350^{TM}$(3M EPSE, USA) composite resin was used for the cavity filling. Sixty permanent bicuspid teeth, that were extracted for orthodontic treatment, were studied. The cavities were prepared on the occlusal surface and were filled using the following methods : 1) bulk filling, 2) parallel filling, 3) oblique filling The strain was recorded on the buccal, lingual, mesial and distal surfaces and the strain values were computed into stress values. The shear bond strength of each filling method was tested using a Micro Universal Testing machine. The results can be summarized as follows: 1. In the strain changes, all LED and PAL curing groups showed an increase on the buccal surface and a slow decrease as time elapsed. 2. In the strain changes of the mesial and distal surfaces, the decreases and increases were shown repeatedly and reduced as time elapsed. 3. There were no significant statistical strain changes among filling methods in the LED or PAL curing groups. 4. There were significant statistical strain changes between the LED and PAL curing groups on the buccal surface(p<0.05). 5. From the shear bond strength results, in the LED curing group, filling method 3 showed lower surface stress than filling method 1 and 2(p<0.05). In the PAL curing group, there were no significant statistical strain changes between each filling method. 6. The surface stress of each group was lower than the shear bond strength.

• Journal of Korean society of Dental Hygiene
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• v.15 no.4
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• pp.705-711
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• 2015

Objectives: The purpose of the study is to evaluate the effect of continuing dental care program by elementary school dental clinic in Gimcheon from 2008 to 2013. Methods: The subjects were experimental group of 152 students from three elementary schools having dental clinics and control group of 136 students from three elementary schools of no dental clinics. The six dentists in Gimcheon community health center carried out the regular dental checkups in the elementary schools and four dental hygienists recorded the dental examination results. After receiving WHO dental survey guideline education, the examiners used dental mirror and dental probe under the natural light. The contents of the survey included dental caries in the deciduous and permanent teeth, malocclusion, remaining ratio of sealant, treatment, and follow up. Results: DFT index by grade showed that 3.71 in experimental group and 4.56 in control group and it was remarkable in the 3rd grade. Thus. DFT index in the experimental group was lower than that of control group (p<0.05). DT index by grade was 0.63 in experimental group and 1.28 in control group marked in the 6th grade. DT index in the control group was higher than that of the experimental group (p<0,001). DFT index and DMFT Index by grade showed no significant difference between the control group and the experimental group. DFT and DMFT Index of the control group in the 3rd and 6th grade were lower score than those of experimental group. DFT and DMFT index in the third and 6th grade showed no significant difference between the control group and the experimental group. The remaining ratio of the sealant was 4.89 experimental group in the 6th grade. The remaining ratio of the sealant in the experimental group was higher than that in the control group. Conclusions: The continuing dental care program in the elementary school is very effective method in the treatment of oral disease in the elementary school children. The oral health care and prevention for the elementary school children should be implemented and carried out continuously.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.8 no.2
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• pp.113-117
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• 2012

Axenfeld-Rieger syndrome (ARS) is a rare disorder with variable morphology characterized by malformations of the anterior segment of the eye such as iris hypoplasia, iridocorneal adhesions, corectopia and polycoria. Craniofacial and dental anomalies are also regularly reported in connection with ARS. Dental features include hypodontia in primary and permanent dentition, microdontia, short roots and abnormally shaped teeth. The patient in this case is a 14-year-old girl who has visited Seoul National Dental Hospital in 2002 for the first time. A panorama was taken on the day of her first visit, and total absence of maxillary anterior dentition and mandibular premolars were observed. The patient was on a treatment schedule by the department of ophthalmology at Seoul National Hospital for a morphological dyplasia of the pupil and she was diagnosed with ARS. Periodic panoramic observations were performed followingly, and she was finally diagnosed of congenital missing of maxillary anteriors and mandibular second premolars. In 2009, composite resin build-ups of maxillary primary central incisors were performed, and she has been on her regular follow-ups until now.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.344-350
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• 2000

Incidence of crown-root fracture due to traumatic injury, have been reported 3% in the permanent dentiton, 2% in the deciduous dentition. There are two treatment methods for crown-root fractured teeth with pulp exposure, when the fracture line was located under the alveolar crest. One way is the extrusion by orthodontic force the other way is intra-alveolar transplantation which occlusally repositioning of apical fragment in the alveolar socket. Since intra-alveolar transplantation has introduced in 1970s, it was practiced as alternative to orthodontic extrusion. As the result, this method may thoughted that had a good prognosis. As a result of trauma, completely crown-root fracture was occured in the maxillary right central incisor in this case. We couldn't reposition the deepest fracture line above the alveolar crest by the conventional surgical extrusion, because apical fragment was too short. Thus, after extraction of apical fragment, we repositioned it to the socket following demineralized freezed dried bone graft, which possible to support the apical fragment. At the 15-month recall examination, the root still showed normal mobility and there was not observed any in flammatory or replacement root resorption in the periapical radiograph.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.305-312
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• 2008

Crown-root fractures occur throughout both crown and root, and are defined as fractures involving enamel, dentin and cementum. The fractures may be grouped according to pulpal involvement into complicated and uncomplicated one. Crown-root fractures often occur on maxillary anterior teeth and comprise 5% of injuries affecting the permanent dentition and 2% in the primary dentition. To restore crown-root fractured tooth, biologic width must be maintained. For maintaining biologic width, such methods as gingivectomy following osteoplasty or orthodontic extrusion or surgical extrusion are available. Surgical extrusion is a method that extracts the tooth and replants the fractured tooth supragingivally. It is indicated when the length of the crown fragment is less than half the length of the clinical root. In these cases, root canal treatment and crown restoration using light-cured composite resin were performed after surgical extrusion. In following periodic examinations, favorable outcome was observed.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.313-318
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• 2008

Dens invaginatus is a rare malformation resulting from invagination of the enamel before calcification has occurred. It is mostly found in permanent maxillary lateral incisors and mandibular teeth are rarely affected by this anomaly. The malformation is estimated to affect between 0.04 % and 10 % of people and has been associated with other abnormalities such as taurodontism, microdontia, gemination and dentinogenesis imperfecta. Dens invaginatus is classified in three types with respect to the depth of invaginatus and has a broad spectrum of morphologic variations. Invagination frequently allows the entry of irritants and microorganism, which usually lead to caries, pulp infection and pulp necrosis. Root canal treatment on such invaginatus tooth may present severe problems because of its complex anatomy of the tooth. Therefore, the early diagnosis of such malformation is crucial and preventive approach is strongly recommended.

• Imaging Science in Dentistry
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• v.37 no.3
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• pp.165-170
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• 2007

Purpose: To estimate the shape of root and pulp canal using a dental cone beam computed tomography (CBCT) and to evaluate the accuracy of imaging reformation. Materials and Methods: CBCT images were obtained with incisors, premolars, and molars as the destination by using PSR $9000N^{TM}$ Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) and i-CAT (Imaging Sciences International, Inc, USA) cone beam CT unit that have different kind of detector and field of view, and compared these with the shape and the size of actual root and root canal. Results: When the measuring value of cone beam computed tomography concerning to each root's bucco-lingual diameter and mesio-distal diameter was compared with the value of the actual root, it reveals an error range $-0.49{\sim}+0.63$ mm at PSR900N and $-0.97{\sim}+1.14$ mm at i-CAT (P>0.05). It was possible to identify and measure PSR$9000N^{TM}$ Dental CT system to the limit $0.48{\pm}0.06mm$ (P>0.05) and i-CAT CBCT to the limit $0.86{\pm}0.09mm$ (P<0.05) on estimating the size and the shape of root canal. Two kinds of CBCT images revealed the useful reproducibility to estimate the shape of root, but there was the difference to estimate the shape of root according to apparatus. The reproducibility of root shape in the image of three-dimensions at PSR 900N is low such as 0.65 mm in a case of minute root canal. Conclusions: CBCT images revealed higher accuracy of the imaging reformation for root and pulp and clinically CBCT is a useful diagnostic tool for the assessment of root and canal. However, there are different qualities of imaging reformation according to CBCT apparatus and limitation of reproducibility for minute root canals.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.149-157
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• 2005

Mechanical removals in decayed teeth have been performed using drill and sharp hand instruments. These methods have some disadvantages such as pain, local anesthesia and overextended cavities Therefore chemo-mechanical excavation of dentin carious lesions has been introduced. The purpose of this study was to evaluate the efficacy of traditional mechanical methods using burs and chemo-mechanical methods (Carisolv) of caries dentin. Mechanical caries removal was carried with low speed round bur Chemo-mechanical caries excavation was performed with Carisolv (Medi-team), using the Carisolv hand instruments. The mean time to remove caries with two different methods was evaluated and the data analyzed with SPSS software (ver 11.5) by t-test (p < 0.05). For histomorphometry of caries removal were also carried with mechanical or chemo-mechanical (Carisolv) methods from 20 extracted caries permanent molars. Complete caries removal was verified with a $\#$23 sharp explorers, Caries Detector (Kuraray Co. Japan), and standard apical radiography. 1. Chemo-mechanical method was taken more times than mechanical method (1.5 fold) (p < 0.05) 2. Excavation for caries took more time for molar lesion than premolar lesion, and the least time was taken to remove the caries in incisor lesion (p < 0.05). 3. There were no significant differences to remove the caries between the maxilla and mandible (p > 0.05). 4. The remaining carious dentin was detected after the ckemo-mechanical removal of the carious dentin, and no smear layer were seen after the mechanical and chemo-mechanical removal of the carious dentin.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.670-674
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• 2005

Supernumerary tooth develops as a result of abnormal proliferation of the dental lamina during the initiation stage of dental development. It could be a sporadic occurrence or a hereditary transmission. Supernumerary tooth occurs with a frequency of 1 to 3%. Generally, there is a 2:1 preference for boys. It is usually found in the anterior portion of the maxilla and may be associated with complications such as impaction, malposition of permanent teeth, formation of diastema, cysts and eruption into nasal cavity, The position of supernumerary tooth found in the anterior portion of the maxilla is determined by the axis of the tooth. One third of supernumerary tooth in the anterior portion of the maxilla has no possibility of eruption due to its invertedly impacted position. However, as long as the coronal part of the follicle remains intact, migration of supernumerary tooth is possible. The migration may occur into the palate, the premolar region, the sinus or the nasal cavity. Also, growth of vertical dimension of maxilla could make surgical approach difficult as time goes by For this reason, we have found invertedly impacted mesiodens moved to the vault of the palate in the two cases, and extracted supernumerary tooth surgically.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.106-121
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• 2007

The purpose of this study was to examine the effects of suggested etching method on the performance of pits and fissures sealant. In the first part, seventy extracted sound human permanent third molars and premolars were used. The teeth were randomly divided and performed in three different groups as follows : conventional etching, enameloplasty, and testing group. Non-pumicing, dye-guidance vigorous brushing-start etching technique was applied on the occlusal of testing group. Then the pit and fissure sealant was applied on all of the specimens. After the thermocycling and immersing in 1% methylene blue, the resin embedded sections were made. The microleakage data on the section were then recorded under the stereoscope and statistic analysis was done. Additional experiments were also performed : direct fissure surface etched pattern experiment, replica study, and micro-shear bond strength testing observation. The second part included two groups. A paired study was designed to evaluate the influence the environment has on the performance of the sealant. After etching, half of each occlusal surface received one of the two following treatments in succession: sealing in laboratory and intraoral condition (group 1), sealing in intraoral condition with and without a single-bonding agent (group 2). The results of present study can be summarized as follows: - The microleakage of testing group was significant different with conventional method (P<.05) and was not different with the enameloplasty group (P>.05). - The quality and quantity of etched enamel were improved. - Microshear bond strength of testing group was higher than control group (p<.05). - The environmental condition was influenced on the performance of the sealant. The testing etching method modified the capacity of the etching agent to penetrate into the pits and fissures, and simultaneous enhance their efficiency in vitro condition.