• The korean journal of orthodontics
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• v.41 no.6
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• pp.423-430
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• 2011

Objective: To evaluate the extent and aspect of stress to the cortical bone after application of a lateral force to a two-component orthodontic mini-implant (OMI, mini-implant) by using three-dimensional finite element analysis (FEA). Methods: The 3D-finite element models consisted of the maxilla, maxillary first molars, second premolars, and OMIs. The screw part of the OMI had a diameter of 1.8 mm and length of 8.5 mm and was placed between the roots of the upper second premolar and the first molar. The cortical bone thickness was set to 1 mm. The head part of the OMI was available in 3 sizes: 1 mm, 2 mm, and 3 mm. After a 2 N lateral force was applied to the center of the head part, the stress distribution and magnitude were analyzed using FEA. Results: When the head part of the OMI was friction fitted (tapped into place) into the inserted screw part, the stress was uniformly distributed over the surface where the head part was inserted. The extent of the minimum principal stress suggested that the length of the head part was proportionate with the amount of stress to the cortical bone; the stress varied between 10.84 and 15.33 MPa. Conclusions: These results suggest that the stress level at the cortical bone around the OMI does not have a detrimental influence on physiologic bone remodeling.

• Journal of Oral Medicine and Pain
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• v.35 no.2
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• pp.119-122
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• 2010

Carbondioxide($CO_2$) laser is one of the most widely employed lasers in oral soft tissue surgery because of its excellent affinity for water based soft tissues. It has some inherent advantages such as hemostasis, less postoperative swelling, reduction of bacterial population at surgical site, less need for suturing, less scarring, and less postoperative pain compared to conventional surgical therapies including the use of scalpel, diathermy, cryotherapy and electrosurgery. A 30-years-old male was presented with gingival swelling. Clinical examination revealed a well?defined pedunculated fibrotic mass on the buccal gingiva near right maxillary 1st molar. In radiographic examination, no remarkable abnormality was seen. Excisional biopsy was performed with $CO_2$ laser (continuous wave mode, 4.0W). Histological diagnosis was "Irritation fibroma". $CO_2$ laser has advantages those are suitable for surgical treatment of intraoral lesion. If appropriate training and experience are provided, the dentist would be able to manage intraoral lesions more efficiently and successfully with the use of the $CO_2$ laser.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.577-577
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• 2001

The lastest concepts in bonding are "total etch", in which both enamel and dentin are etched with an acid to remove the smear layers, and "wet dentin" in which the dentin is not blown dry but left moist before application of the bonding primer. Ideally, the application of a bonding agent to tooth structure should be insensitive to minor contamination from oral fluids. Clinically contaminations such as saliva, gingival fluid, blood and handpiece lubricant are often encountered by dentists during preparation of a restoration. The aim of this study was to evaluate the effect of contamination by hem-ostatic agents on shear bond strength of compomer restorations. One hundred and ten extracted human maxillary and mandibular molar teeth were collected. The teeth were cleaned from soft tissue remnant and debris and stored in physiologic solution until they were used. Small flat area on dentin of the buccal surface were wet ground serially with 400, 800 and 1200 abrasive paper on automatic polishing machine. The teeth were randomly divided into 11 groups. Each group was conditioned as follows: Group 1 : Dentin surface was not etched and not contaminated by hemostatic agents. Group2 : Dentin surface was not etched but was contaminated by Astringedent (Ultradent product Inc., Utah, U.S.A.). Group3 : Dentin surface was not etched but was contaminated by Bosmin (Jeil Phann, Korea.). Group4 : Dentin surface was not etched but was contaminated by Epri-dent (Epr Industries, NJ, U.S.A.). Group5: Dentin surface was etched and not contaminated by hemostatic agents. Group 6 : Dentin surface was etched and contaminated by Astringedent. Group7 : Dentin surface was etched and contaminated by Bosmin. Group8 : Dentin surface was etched and contaminated by Epri-dent. Group9 : Dentin surface was contaminated by Astringedent. The contaminated surface was rinsed by water and dried by compressed air. Group10 : Dentin surface was contaminated by Bosmin. The contaminated surface was rinsed by water aud dried by compresfed air. Group 11 : Dentin surface was contaminated by Epri-dent. The contaminated surface was rinsed by water and dried by compresfed air. After surface conditioning, F2000 was applicated on the conditoned dentin surface. The teeth were thermocycled in distilled water at $5^{\circ}C\;and\;55^{\circ}C$ for 1000 cycles. The samples were placed on the binder with the bonded compomer-dentin interface parallel to the lmife-edge shearing rod of the Universal testing machine(Zwick 020, Germany) running at a cross head speed of 1.0mmimin. There were no significant differences in shear bond strength between groups 1 and group 3 and 4, but group 2 showed significant decrease in shear bond strength compared with group 1. There were no significant differences in shear bond strength between group 5 and group 7 and 8, but group 6 showed significant decrease in shear bond strength compared with group 5. There were no significant differences in shear bond strength between group 5 and group 9, 10 and 11.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.245-257
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• 1998

This study was performed to measure the changes of the mandibular movement and the masticatory muscular activities - anterior temporal and masseter muscle of both side - reflected by intentional increase of anterior guidance angie. For this study, 5 volunteers (3 males and 2 females with average age of 24.0) were selected. Each volunteer had Angle's classification I and did not have any missing tooth except third molar and any extensive restorations. Metallic guide plate was made at volunteer's working model fabricated by improved dental stone and cemented to the palatal surface of maxillary central incisor using resin cement(Panavia $21^{(R)}$) and then adjusted not to give any occlusal interferences at intercuspal position. The activity of masticatory muscles and the changes of mandibular movement were recorded by EMG and Sirognathograph in Biopak analysing system(Bioresearch Inc., Milwaukee, Wisconsin, USA). Measurement was done at before experiment, immediatley after placement, 1 week after placement, immediately after removal, and 1 week after removal. The results were as follows: 1. Moderate phonetic disturbance and mild headache were occured to 3 volunteers for 2 days after setting and 1 volunteer had positive reaction to percussion and slight midline diastema. But all of these clinical signs were diappeared 1 week after removal and the other volunteer did not have any special clinical sign. 2. In the EMG of the mandibular rest position, the mean value of anterior tempotal muscle was increased immediately after placement(p<0.01) and then decreased 1 week after placement(p<0.05) and increased 1 week after removal(p<0.05) but not recovered as before experiment. The mean value of masseter muscle was decreased during the experiment period. 3. In the EMG during mandibular protrusive movement, all muscular activity was decreased during the experiment period. Reduced activity was not recovered 1 week after removal(p<0.03). 4. During the habitual opening, anteroposterior movement of mandible was decreased immediately after placement(p<0.05) and then increased 1 week after placement but not statistically significant(p>0.1). Vertical movement was not shown significant difference during the experiment period(p>0.1). Lateral movement was decreased immediately after placement(p<0.05) and then increased 1 week after placement but not recovered as before experiment. The opening and closing velocity of mandible was shown minor changes but not statistically significant. 5. During the habitual opening, anteroposterior movement of mandible was decreased 1 week after placement(p<0.05) and then increased immediately after removal and recovered 1 week after removal as before experiment. Vertical movement was not shown significant changes. Lateral displacement of mandible was increased continuously and recovered 1 week after removal. Opening velocity was temporarily increased immediately after removal but recovered and closing velocity was not shown significant changes. 6. During the right side chewing, anteroposterior movement of mandible was increased immediately after removal but recovered and vertical movement was not shown statistically significant results. Lateral displacement and velocity of mandible were not shown significant results. 7. During the left side chewing, the changes of mandibular movement pattern were not shown statistically significant results.

• Journal of Veterinary Clinics
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• v.22 no.1
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• pp.31-35
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• 2005

This study was performed to investigate of dental plaque, calculus and gingival inflammation in Beagle dogs. Forty adults Beagle dogs (28 male and 12 female) were used in this study. The dogs weighed 9.5 kg and were in good oral and systemic health as determined by physical examination, and all dogs had full and normal dentition. The dogs were given a commercial pellet feed during 2 years period. For all examination procedures, the dogs were premedicated with a subcutaneous injection of atropine sulfate (0.04 mg/kg). Anesthesia was induced and maintained by intravenous administration of ketamine (8 mg/kg) and xylazine (2 mg/kg). Dental plaque, calculus and gingival inflammation were assessed by Logan and Boyce clinical plaque index. Calculi covering the maxillary carnassial and first molar teeth were extensive and were accompanied by severe gingival inflammation and pocket formation. Calculi, accompanied by gingival inflammation, were clearly evident on buccal surfaces of other teeth. Calculi didn't showed on the lingual surfaces, but linguogingival inflammation formed in premolar teeth. Although the general pattern was clear, there was considerable variation among dogs in the rate of deposition of calculus and extend of gingival inflammation. This investigation suggest that feeding of the commercial dry food without dental hygiene increase plaque accumulation and may be a contributing factor in calculi formation and periodontal disease.

• Journal of Periodontal and Implant Science
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• v.31 no.4
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• pp.669-687
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• 2001

On the basis of the evidence that electrical stimulation could promote healing and regeneration of bone, this study was performed to investigate the effects of electrical stimulation on rat extraction socket, and to evaluate the potential of clinical application of electrical stimulation. Forty rats were used and divided into control groups(l0)and the experimental groups(30) in this study. The maxillary 1st molar were extracted in both groups. In experimental group, electrical stimulation was given at the current intensity of lmA(Test-1), l0mA(Test-2), 25mA(Test-3) each day. At 1,3,5,7 days after the tooth extraction, rats in both groups were serially sacrificed. And the specimens were prepared with Hematoxylin-Eosin stain for the light microscopic evaluation. The results of this study were as follows; 1. At 1 day after the extraction, the periodontal ligament was found in the extraction socket wall. The formation of blood clot with dense infiltration of inflammatory cells in control group and there were less inflammatory cells in test group. 2. At 3 day after the extraction, the cells and collagen of the periodontal ligament were so actively proliferated and synthesized that invaded into the connective tissue of the extraction sockets in the control group. There were the formation of new bone in the basal & lateral portion of socket wall in test -2 and -3. 3. At 5 days after the extraction, there were no formation of new bone in control group. But the more electrical stimulation was applied, the more formation of new bone in test group. 4. At 7 days after the extraction, the extraction sockets were almost filled with trabecular bone in each group. Bone maturarity was remarkable in test-3. 5. The electrical stimulation at l0mA and 25mA was more effective in the bone formation at 5 and 7 days after the extraction. From the above results, electrical stimulation could promote the extraction socket wound healing, and be utilized in the clinical application of the residual ridge expansion.

• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.1-7
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• 2014

PURPOSE. The accuracy of a gypsum model (GM), which was taken using a conventional silicone impression technique, was compared with that of a polyurethane model (PM), which was taken using an iTero$^{TM}$ digital impression system. MATERIALS AND METHODS. The maxillary first molar artificial tooth was selected as the reference tooth. The GMs were fabricated through a silicone impression of a reference tooth, and PMs were fabricated by a digital impression (n=9, in each group). The reference tooth and experimental models were scanned using a 3 shape convince$^{TM}$ scan system. Each GM and PM image was superimposed on the registered reference model (RM) and 2D images were obtained. The discrepancies of the points registered on the superimposed images were measured and defined as GM-RM group and PM-RM group. Statistical analysis was performed using a Student's T-test (${\alpha}=0.05$). RESULTS. A comparison of the absolute value of the discrepancy revealed a significant difference between the two groups only at the occlusal surface. The GM group showed a smaller mean discrepancy than the PM group. Significant differences in the GM-RM group and PM-RM group were observed in the margins (point a and f), mesial mid-axial wall (point b) and occlusal surfaces (point c and d). CONCLUSION. Under the conditions examined, the digitally fabricated polyurethane model showed a tendency for a reduced size in the margin than the reference tooth. The conventional gypsum model showed a smaller discrepancy on the occlusal surface than the polyurethane model.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.1-8
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• 2017

Purpose: The purpose of this study is to compare the accuracy of the CT guided implant template that was produced by using an intraoral scanner according to the edentulous distance. Materials and methods: Five maxillary casts were fabricated using radiopaque acrylic resin with the second premolars, first molars, and second molars missing. Then a virtual cast was acquired by scanning each resin cast. Implant treatment was planned on the missing sites by superimposing the presurgical CT DICOM file and the virtual cast. Then the implants were placed using a surgical template followed by postsurgical CT scan. The distance and angle of the platform and apex between the presurgical implant and postsurgical implant were measured using the X, Y, and Z axis of the superimposed presurgical CT and postsurgical CT via software followed by statistical analysis using Kruskall-Wallis test and Mann-Whitney test. Results: The implant placement angle error increased towards the second molars but there was no statistically significant difference. The implant placement distance error at the platform and apex also increased towards the second molars and there was a statistically significant error at the second molars. Conclusion: Although the placement angle had no statistically significant difference between the presurgical implant and postsurgical implant, the placement distance at the platform and apex showed a larger error and a statistically significant difference at the second molar implant.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.256-261
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• 2005

Scleroderma is a connective tissue disease of unknown etiology, but known as a kind of auto-immune disease. It is most common in women especially in $30{\sim}50$ years, and very rare in childhood. It can be classified into two main classes : localized scleroderma & systemic sclerosis. Localized type has better prognosis, and usually involves skin only, or in some cases, the muscle below, except inner organs. Systemic type involves skin, oral mucosa and major internal organs. Involving facial skin, we can see small and sharp nose, expressionless stare and narrow oral aperture. Usually they have Raynaud's phenomenon, and in progress, show mouth opening limitation and sclerosis of tongue and gingiva. It is called CREST syndrome showing calcinosis cutis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, and telangioectasia. Treatment of scleroderma is systemic and localized steroid therapy, use of collagen-link inhibitor (D-penicillamine), immune depressor and etc. Mouth opening limitation can be improved by mouth stretching exercise. We report a 6 years old boy, diagnosed with localized scleroderma who had mouth opening limitation. We could get additional mouth opening, and have done successful restorative treatment of mandibular and maxillary 1st and 2nd deciduous molar under deep sedation with nitrous oxide and enflurane.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.4
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• pp.376-382
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• 2011

In clinical dentistry, it is not difficult to meet the permanent first molars with severe coronal caries lesions in children or adolescents. The circumstances surrounding the first molars of children and adolescents are so immature and imperfect compared with those of adults. So we thought it significant to understand the status of these teeth at the moment of endodontic treatment and immediate cause of it. 106 patients with 135 permanent molars necessitating endodontic treatment in childhood and adolescence were included in this study, and the dental records and radiographs were examined. 1. The mean age was 11.9 year (male 11.5, female 12.5) and the result shows significant difference between gender(p<0.05). The mandibular teeth took more than half percentage than maxillary teeth. 2. Of 135 teeth, 45.2 percent of teeth had history of dental treatment previously and 16.3 percent of teeth showed necessity of re-endodontic treatment. 3. Of 73 teeth, 22 teeth had mesial-wall cavity causing endodontic treatment, 39 had occlusal cavity, and 12 had distal cavity.