• Journal of Periodontal and Implant Science
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• v.38 no.3
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• pp.551-556
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• 2008

Purpose: Cemental tear is an uncommon form of root fracture that can lead to rapid localized attachment loss. When it is exposed in the periodontal pocket, it should be removed to prevent accumulation of dental plaque and calculus. Material and Methods: 2 patients were diagnosed as a cemental tear and they were treated with conventional flap operation and subgingival curettage. Additional treatments such as bone graft or guided tissue regeneration were not performed. Result: Symptoms subsided after the treatment. Periodontal pocket has been reduced but no gain of clinical attachment was observed. Remnant of cemental fragment remained after curettage. However, periodontal pocket was stably maintained and there was no recurrence. Conclusion: Periodontal attachment loss associated with cemental tear can be successfully treated with conventional periodontal surgical and nonsurgical procedures.

• Restorative Dentistry and Endodontics
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• v.26 no.1
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• pp.64-76
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• 2001

Despite the improvements in bond strengths of dentin adhesives and resin-modified glass ionomers, the marginal seal of cervical restorations remains a concern. Microleakage at poorly sealed margins can result in staining, post-operative sensitivity, pulpal irritation, and recurrent caries. The objective of this study was to evaluate the effect of surface penetrating sealant(SPS) on the microleakage of cervical restorations. 45 extracted human teeth were selected, and Class V preparations were prepared on the both buccal and lingual surface of the teeth to the following dimensions : 1.5mm axially, 3mm mesiodistally, and 3mm incisogingivally. After cervical restoration with composite resin, compomer, glass ionomer each restoration was treated as three methods: No Tx., Scotchbond Multipurpose Adhesive$^{\circledR}$, Fortify$^{\circledR}$. The sections were examined with a stereomicroscope to determine the extent of microleakage at enamel and dentin margins. The results of this study were as follows. 1. All groups showed some microleakage. 2. Gingival cavity wall with cementum margin showed significantly higher leakage value than occlusal cavity wall with enamel margin. 3. The group treated with SPS showed significantly lower leakage value than no treated group(p<0.05). But there is no difference between Fortify$^{\circledR}$ and Scotchbond Multipurpose adhesive$^{\circledR}$. The results of this study suggest that SPS are effective in reducing microleakage of class V restorations. But it is certain that some microleakage still occurred despite the application of SPS.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.296-303
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• 1998

The purpose of this study was to assess the effects of cavity designs on the marginal leakage of class 5 glass ionomer restorations. The five cavity designs were as follows ; notch shape(A group), notch shape with groove(B group), combined lesion(C group), combined lesion with groove and deep chamfer margin(D group) and combined lesion with groove and shoulder(E group), and each design had 10 cavities. After the cavities were restored with GIC, they were immersed in 0.5% basic fuchsin solution for 6 hours. The specimens were washed thoroughly and sectioned longitudinally in a buccolingual direction through the center of the restorations. The degree of marginal leakage was measured as the extent of dye penetration under the stereoscope. The results of this study were as follows 1. The enamel margins of all groups showed lesser leakage than dentin/cementum margins(p<0.05). 2. The combined lesion(C group) showed more leakage than notch shape(A group), but there was no siginificant difference(p>0.05). 3. In the notch shape, there was no influence on the marginal leakage by the groove preparation. 4. In the combined lesion, marginal leakage was decreased by the groove preparation and marginal modification.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.159-169
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• 2000

The purpose of this study was to examine the tissue response to experimental furcation perforations immediately treated with Super EBA, Ketac Silver, MTA and Emdogain using surgical microscope. Forty experimental furcation perforations were created in the mandibular and maxillary premolars and molars of 4 adult dogs and immediately repaired with experimental materials. The animals were sacrificed after 16 weeks and radiographic and histologic results were evaluated. The results were as follows. 1 All materials tested in this experiment revealed a certain degree of extrusion of the filling materials and infiltration of inflammatory cells into the periodontal space. Except MTA group, epithelial down-growth of the surrounding gingiva was found in all experimental groups. 2. Both Ketac Silver and Emdogain group showed the greatest degree of inflammatory reaction and bone resorption. 3. Super EBA group showed moderate inflammation and newly bone formation under the perforation area. 4. MTA group showed minor inflammation, new bone regeneration toward restorative materials and partially cementum growth onto the surface of the material. This group demonstrated a favorable prognosis.

• Imaging Science in Dentistry
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• v.51 no.4
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• pp.447-454
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• 2021

A 16-year-old male presented with pain in the right posterior mandible on chewing that had lasted for several months. The radiographic features of the lesion included a radiolucent-radiopaque mixed-density mass with a radiolucent rim attached to the root of the mandibular right first molar. The preliminary radiographic diagnosis was benign cementoblastoma, which was confirmed by histopathological examination following surgical excision. The lesion recurred 3 years after treatment; radiographically, it consisted of 3 round foci with mixed radiopacity, each with a radiolucent rim near the root of the mandibular right second premolar and the edentulous postoperative region. The lesion was diagnosed as recurrent benign cementoblastoma and a second surgery was scheduled. This report presented an unusual case of recurrent benign cementoblastoma following surgical excision and extraction of the involved tooth, along with a literature review on reported cases of recurrent benign cementoblastoma with a focus on its clinical features and the best treatment options.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.535-563
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• 1993

New techniques for regenerating the destructed periodontal tissue have been studied for many years. Current acceptable methods of promoting periodontal regeneration alre basis of removal of diseased soft tissue, root treatment, guided tissue regeneration, graft materials, biological mediators. Platelet-derived growth factor (PDGF) is one of polypeptide growth factor. PDGF have been reported as a biological mediator which regulate activities of wound healing progress including cell proliferation, migration, and metabolism. The purposes of this study is to evaluate the possibility of using the PDGF as a regeneration promoting agent for furcation involvement defect. Eight adult mongrel dogs were used in this experiment. The dogs were anesthetized with Pentobarbital Sodium (25-30 mg/kg of body weight, Tokyo chemical Co., Japan) and conventional periodontal prophylaxis were performed with ultrasonic scaler. With intrasulcular and crestal incision, mucoperiosteal flap was elevated. Following decortication with 1/2 high speed round bur, degree III furcation defect was made on mandibular second(P2) and fourth(P4) premolar. For the basic treatment of root surface, fully saturated citric acid was applied on the exposed root surface for 3 minutes. On the right P4 20ug of human recombinant PDGF-BB dissolved in acetic acid was applied with polypropylene autopipette. On the left P2 and right P2 PDGF-BB was applied after insertion of ${\beta}-Tricalcium$ phosphate(TCP) and collagen (Collatape) respectively. Left mandibular P4 was used as control. Systemic antibiotics (Penicillin-G benzathine and penicillin-G procaine, 1 ml per 10-25 1bs body weight) were administrated intramuscular for 2 weeks after surgery. Irrigation with 0.1% Chlorhexidine Gluconate around operated sites was performed during the whole experimental period except one day immediate after surgery. Soft diets were fed through the whole experiment period. After 2, 4, 8, 12 weeks, the animals were sacrificed by perfusion technique. Tissue block was excised including the tooth and prepared for light microscope with H-E staining. At 2 weeks after surgery, therer were rapid osteogenesis phenomenon on the defected area of the PDGF only treated group and early trabeculation pattern was made with new osteoid tissue produced by activated osteoblast. Bone formation was almost completed to the fornix of furcation by 8 weeks after surgery. New cementum fromation was observed from 2 weeks after surgery, and the thickness was increased until 8 weeks with typical Sharpey’s fibers reembedded into new bone and cementum. In both PDGF-BB with TCP group and PDGF-BB with Collagen group, regeneration process including new bone and new cementum formation and the group especially in the early weeks. It might be thought that the migration of actively proliferating cells was prohibited by the graft materials. In conclusion, platelet-derived growth factor can promote rapid osteogenesis during early stage of periodontal tissue regeneration.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.367-373
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• 1992

The author observed a 35-year-old male patient who came to the Dental Infirmary of Kyungpook National University Hospital who had complained of gradual swelling on both side of the mandible for 15 years. As a result of careful analysis of clinical, radiological and histopathological findings, the authors diagnosed it as cementifying fibroma and obtained the results as follows: 1. In clinical examination, main clinical symptom was facial deformity due to gradual swelling on both side of the mandible. 2. In radiographic examination, radiolucent lesions with central radiopaque foci were seen on both mandibular body areas bilaterally, and cortical thinning and expansion of the mandibular body were seen buccolingually. And loss of lamina dura and root resortption of adjacent teeth were also seen. In histopathological examination, this lesion was composed of delicate interlacing collagen fibers interspersed by the fibroblasts and cementoblasts. And round or oval shaped basophilic masses of cementum-like tissue were observed in the connective tissue.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.41-48
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• 1986

It is known that radiation therapy is a kind of treatment choices of the maxillofacial tumors. This study is designed to investigate the irradiation effects on rat's periodontal tissues as functional tissues which relate to tooth-support, hard tissue formation and destruction. 20 rats (Sprague-Dowley branch, male) were devided into control group of 4 and experimental groupe of 16. Experimental group was singly exposed to Co-60 irradiation with 10 Gy in the head and neck region. Animals were sacrificed on 2 days, 1 week, 2 weeks and 3 weeks after the irradiation. The specimens were observed by histopathological examination employing H-E stain, van-Gieson stain and PA-ACH fluorescent stain. The results were as follows: 1. Cementoblasts and osteoblasts were gradually lost and rearranged along the external surfaces of the cementum and alveolar bone, but osteoclasts were almost not affected. 2. The cell numbers of the periodontal ligament were decreased due to the cellular atrophy and degeneration, but recovered almost normally on the 3rd week after irradiation. 3. The collagen fibers within the periodontal ligament were irregularly oriented, became finer and decreased in number. 4. The vessels of the periodontal ligament were decreased at the initial stage but increased again on the 2nd week after irradiation, and the hemorrhagic appearances, occurred within the tissues, due to the arterial destruction, were lasted until 3 weeks after irradiation. 5. The glycogen within the periodontal ligament was gradually increased and stored in the matrices of the cemental side on the 1st week after irradiation, but recovered almost normally on the 3rd week after irradiation.

• Restorative Dentistry and Endodontics
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• v.38 no.1
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• pp.26-30
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• 2013

Objectives: The aim of this study was to investigate the relationship between the apical foramen morphology and the length of merged canal at the apex in type II root canal system. Materials and Methods: This study included intact extracted maxillary and mandibular human premolars (n = 20) with fully formed roots without any visible signs of external resorption. The root segments were obtained by removing the crown 1 mm beneath the cementum-enamel junction (CEJ) using a rotary diamond disk. The distance between the file tip and merged point of joining two canals was defined as Lj. The roots were carefully sectioned at 1 mm from the apex by a slow-speed water-cooled diamond saw. All cross sections were examined under the microscope at ${\times}50$ magnification and photographed to estimate the shape of the apical foramen. The longest and the shortest diameter of apical foramen was measured using ImageJ program (1.44p, National Institutes of Health). Correlation coefficient was calculated to identify the link between Lj and the apical foramen shape by Pearson's correlation. Results: The average value of Lj was 3.74 mm. The average of proportion (P), estimated by dividing the longest diameter into the shortest diameter of the apical foramen, was 3.64. This study showed a significant negative correlation between P and Lj (p < 0.05). Conclusions: As Lj gets longer, the apical foramen becomes more ovally shaped. Likewise, as it gets shorter, the apical foramen becomes more flat shaped.

• Journal of Oral Medicine and Pain
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• v.41 no.3
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• pp.85-90
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• 2016

Purpose: The aim of this study was to develop an automated software to extract tooth and pulpal area from sectional cone-beam computed tomography (CBCT) images, which can guarantee more reproducible, objective and time-saving way to measure pulp/tooth volume ratio. Methods: The software program was developed using MATLAB (MathWorks). To determine the optimal threshold for the region of interest (ROI) extraction, user interface to adjust the threshold for extraction algorithm was added. Default threshold was determined after several trials to make the outline of extracted ROI fitting to the tooth and pulpal outlines. To test the effect of starting point location selected initially in the pulpal area on the final result, pulp/tooth volume ratio was calculated 5 times with different 5 starting points. Results: Navigation interface is composed of image loading, zoom-in, zoom-out, and move tool. ROI extraction process can be shown by check in the option box. Default threshold is adjusted for the extracted tooth area to cover whole tooth including dentin, cementum, and enamel. Of course, the result can be corrected, if necessary, by the examiner as well as by changing the threshold of density of hard tissue. Extracted tooth and pulp area are reconstructed three-dimensional (3D) and pulp/tooth volume ratio is calculated by voxel counting on reconstructed model. The difference between the pulp/tooth volume ratio results from the 5 different extraction starting points was not significant. Conclusions: In further studies based on a large-scale sample, the most proper threshold to present the most significant relationship between age and pulp/tooth volume ratio and the tooth correlated with age the most will be explored. If the software can be improved to use whole CBCT data set rather than just sectional images and to detect pulp canal in the original 3D images generated by CBCT software itself, it will be more promising in practical uses.