• Journal of Periodontal and Implant Science
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• v.47 no.1
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• pp.41-50
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• 2017

Purpose: The aims of the present study were to compare the image quality and visibility of tooth cracks between conventional methods and swept-source optical coherence tomography (SS-OCT) and to develop an automatic detection technique for tooth cracks by SS-OCT imaging. Methods: We evaluated SS-OCT with a near-infrared wavelength centered at 1,310 nm over a spectral bandwidth of 100 nm at a rate of 50 kHz as a new diagnostic tool for the detection of tooth cracks. The reliability of the SS-OCT images was verified by comparing the crack lines with those detected using conventional methods. After performing preprocessing of the obtained SS-OCT images to emphasize cracks, an algorithm was developed and verified to detect tooth cracks automatically. Results: The detection capability of SS-OCT was superior or comparable to that of trans-illumination, which did not discriminate among the cracks according to depth. Other conventional methods for the detection of tooth cracks did not sense initial cracks with a width of less than $100{\mu}m$. However, SS-OCT detected cracks of all sizes, ranging from craze lines to split teeth, and the crack lines were automatically detected in images using the Hough transform. Conclusions: We were able to distinguish structural cracks, craze lines, and split lines in tooth cracks using SS-OCT images, and to automatically detect the position of various cracks in the OCT images. Therefore, the detection capability of SS-OCT images provides a useful diagnostic tool for cracked tooth syndrome.

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.585-595
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• 1997

Removal of subgingival calculus is essential for the success in periodontal treatment. Subgingival instrumentation is used for the removal of all bacterial plaque and calculus. In this study, two types of anterior curet were used on ant. teeth to conduct subgingival scaling and root planing. The remaining amount of calculus was evaluated according to type of instrument, depth of pocket, and tooth surface. 24 teeth extracted from patients being treated at Dan Kook University dept. Perio. were used. 4 surfaces per tooth a total of 96 areas were evaluated. 12 teeth treated with Gracey No. 1-2 was used as the control group and 12 teeth treated with Mini-five curet No. 1-2 was the experimental group. The 4 surfaces of the teeth {buccal, mesial, lingual or palatal, distal) were observed under a stereomicroscope and the images were captured 3 times per surfaced with a CCD. The image were observed on the monitor using a $10{\times]10$ grid produced with the Microsoft power point. The amount of calculus remaining was evaluated 3 times per surface. The results were as follows. 1. There was no significant difference in remaining calculus according to the pre-treatment pocket depth, and tooth position{Mx. or Mn). 2. The Mini-five curet showed better results than the Gracey curet but there was no statistically significant difference. 3. In both Gracey curet group and Mini-five curet group the lingual(or palatal) surface showed significant difference compared to the other surfaces(p<0.05). From the results above, it is thought that when treating ant. teeth consideration of the tooth surface is more important than the choice of instrument.

• Archives of Craniofacial Surgery
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• v.18 no.4
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• pp.249-254
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• 2017

Background: Lower eyelid incisions are widely used for the orbital approach in periorbital trauma and aesthetic surgery. In general, the subciliary approach is known to cause disposition of the lower eyelid by scarring the anterior lamella in some cases. On the other hand, many surgeons believe that a transconjunctival approach usually does not result in such complications and is a reliable method. We measured positional changes in the lower eyelid in blowout fracture repair since entropion is one of the most serious complications of the transconjunctival orbital approach. Methods: To measure the positional changes in the lower eyelids, we analyzed preoperative and postoperative photographs over various time intervals. In the analysis of the photographs, marginal reflex distance 2 ($MRD_2$) and eyelash angle were used as an index of eyelid position. Statistical analyses were performed to identify the significance in the positional changes. All patients underwent orbital reconstruction through a transconjunctival incision by a single plastic surgeon. Results: In 42 blowout fracture patients, there was no statistical significant difference in the MRD2 and eyelash angle. Furthermore, there were no clinical complications, such as infection, hematoma, bleeding, or implant protrusion, during the follow-up periods. Conclusion: The advantages of the transconjunctival approach for orbital access include minimal scarring and a lower risk of eyelid displacement compared with other approaches. Based on these results, we recommend the transconjunctival approach for orbital exposure as a safe and reliable method.

• Journal of Periodontal and Implant Science
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• v.52 no.2
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• pp.91-115
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• 2022

Purpose: This systematic review aimed to compare the efficacy, defined in terms of the mean percentage of root coverage (mRC), of surgical treatment approaches combined with adhesive restorations of non-carious cervical lesions (NCCLs) to that of root coverage alone in patients with a single gingival recession (GR) and NCCL. Methods: A literature search was conducted to identify longitudinal studies reporting the mRC following treatment for the correction of GR defects associated with NCCLs using a combination of surgical and restorative techniques in systemically and periodontally healthy patients. Results: The search resulted in the retrieval of 12,409 records. Seven publications met the inclusion criteria for the qualitative synthesis of data. The mRCs ranged from 69% to 97%. In the medium term, the gingival margin position was more stable when a connective tissue graft (CTG) was used, independently of whether restoration of teeth with NCCLs was performed. Conclusions: The strength of the evidence was limited by methodological heterogeneity in terms of study design as well as the unit and period of analysis, which precluded a metaanalysis. Although no definitive conclusion could be drawn due to the lack of sufficient evidence to estimate the effectiveness of the interventions, CTG-based procedures contributed to gingival margin stability regardless of the performance of restoration to treat NCCLs.

• Clinics in Shoulder and Elbow
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• v.26 no.2
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• pp.117-125
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• 2023

Background: Preoperative traditional software planning (TSP) is a method used to assist surgeons with implant selection and glenoid guide-pin insertion in shoulder arthroplasty. Mixed reality (MR) is a new technology that uses digital holograms of the preoperative plan and guide-pin trajectory projected into the operative field. The purpose of this study was to compare TSP to MR in a simulated surgical environment involving insertion of guide-pins into models of severely deformed glenoids. Methods: Eight surgeons inserted guide-pins into eight randomized three-dimensional-printed severely eroded glenoid models in a simulated surgical environment using either TSP or MR. In total, 128 glenoid models were used and statistically compared. The outcomes compared between techniques included procedural time, difference in guide-pin start point, difference in version and inclination, and surgeon confidence via a confidence rating scale. Results: When comparing traditional preoperative software planning to MR visualization as techniques to assist surgeons in glenoid guide pin insertion, there were no statistically significant differences in terms of mean procedure time (P=0.634), glenoid start-point (TSP=2.2±0.2 mm, MR=2.1±0.1 mm; P=0.760), guide-pin orientation (P=0.586), or confidence rating score (P=0.850). Conclusions: The results demonstrate that there were no significant differences between traditional preoperative software planning and MR visualization for guide-pin placement into models of eroded glenoids. A perceived benefit of MR is the real-time intraoperative visibility of the surgical plan and the patient's anatomy; however, this did not translate into decreased procedural time or improved guide-pin position.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.3
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• pp.146-157
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• 2023

The bite collapses due to posterior teeth loss or wear results in inadequate space for restoration and esthetic concerns. Increasing the occlusal vertical dimension to improve space deficiency rotates the mandible posteriorly, creating a gap between the maxillary and mandibular anterior teeth, leading to loss of anterior guidance. To solve this problem, the prosthodontics or orthodontics treatments are the commonly used methods for proper anterior guidance. However, it is reasonable to assume that the anterior teeth can naturally relapse to their original position when the occlusal force is eliminated. Therefore, this case report aimed to test whether natural relapse could recover the lost anterior guidance to develop a less invasive and more convenient treatment method. Digital superimposition was used to evaluate the changes in anterior teeth alignment to confirm the change of the recovered anterior guidance. The appropriate indications for this new treatment method were defined and applied clinically.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.519-531
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• 2003

The aim of present investigation was to clinically measure the thickness of palatal masticatory mucosa in the hard palate as potential donor site for mucogingival surgery, to determine the relation to shape of palatal vault, form of tooth, gender, and to serve the clinical criteria t o choose the proper surgical technique. 84(mean age:25yrs) systemically and periodontally healthy volunteers participated in this study and 18 standard measurement points were defined in the hard palate, located on 3 lies which ran at different distances parallel to the gingival margin. 6 positions were designated on each of these 3 lines between the level of canine and 2nd molar and a bone sounding technique using a periodontal probe with minimal local anesthesia was utilized to assess the thickness of palatal masticatory mucosa. Student t-test was used to determine the difference in mucosal thickness between 2 groups gender, shape of palatal vault (high palatal vault vs. low palatal vault), tooth form (short-wide vs. long narrow) The result of this study were as follows: 1. Soft tissue thickness progressively increased in sites further away from the gingival margin (p<0.01). 2. Depending on position, in line a and line c the masticatory mucosal thickness increased from Ca to M2(p<0.01), but in line b the thickness increased from Ca to P2, and decreased to M1 and increased again to M2. 3. Gender did not influence the thickness of masticatory mucosa. 4. Palatal vault shape was associated with the thickness of masticatory mucosa. Thickness of low palatal vault group was thicker than high palatal group between P2 and M2 position. 5. Form of tooth did not influence the thickness of masticatory mucosa. In conclusion, palatal vault shape was associated with the thickness of masticatory mucosa. So, mucogingival surgery can be considered as a treatment modality in high palatal vault group. But, Gender and tooth form did not influence the thickness of masticatory mucosa.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.108-115
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• 2017

Numerous therapeutic approaches are available for impacted teeth, including orthodontic retraction, implantation, and autogenous tooth transplantation. Autotransplantation is a promising method, especially for juvenile patients, as it enables preservation of the function of the periodontal tissues, as well as continued alveolar bone growth. This report describes autotransplantation in two cases in which the tooth was fully-ectopically impacted. With case 1, an ectopically impacted premolar was extracted and transplanted in an upright position, and regenerative endodontic treatment was performed using a platelet-rich fibrin clot and mineral trioxide aggregate (MTA). With case 2, a calcifying odontogenic cyst with an impacted left mandibular second molar was treated by enucleation. The tooth was transplanted into the proper position 3 months after enucleation, and endodontic treatment was performed using MTA. In both cases, autotransplantation appeared to provide a simple and rapid treatment option for patients with ectopically impacted teeth. These cases demonstrate that autotransplantation of ectopically impacted teeth is a viable treatment option rather than implant placement or prosthesis, especially in juvenile patients.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.252-266
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• 2004

This study analyzes the influence of the construction of a high-speed railroad on territorial organization in France. After development of a new transportation network, the French territorial organization has been largely modified. Many economic urban areas are modified by their position in the territorial hierarchy according to their condition of connection with the TGV network. At first, spatial convergence is the most important effect of the TGV network construction. Second, the development of a transportation network concentrated in the Paris area has influence as an intensified factor on metropolitan areas and as a weakening factor on middle- and small-sized cities. Thus, this system has risk in increasing territorial imbalance in France. Third, to implant an economic activity zone around new TGV stations, a new town or a new economic center starts to develop. This is going to grow into a second core outside of the old city center so that regional spatial organization is transformed from a mono-polarized(mono-centric) organization to a multi-polarized(polycentric) one. Lastly, the integration of the EU railroad system enhances the concentration of economic activity in European metropolitan areas as each metropolitan area tries to develop more competitive space for its rising position in the global urban hierarchical system.

• Journal of Yeungnam Medical Science
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• v.7 no.1
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• pp.81-93
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• 1990

The author fractographically analyized the cause of metal failure(the first time this procedure has been used for this metal failure)and also analyized it clinically. In this study, I selected eight cases which have been analyized fractographically. In all these cases, the analysis was done after treatment of metal failure of implants internally fixed to femur shaft fractures at the Department of Orthopedic Surgery, Yeung-Nam University Hospital during the six year period from May 1983 to September 1989. 1. Metal failure occured in five dynamic-compression plates, one Jewett nail, one screw in Rowe plate, and one interlocking nail. 2. The clinical cause of metal failure was deficiency of medial butress in five cases, incorrect position of implant in one case, and incorrect selection of implant in two cases. 3. The time interval between internal fixation and metal failure was four months in one case, between five months to twelve months in six cases, three years in one case. 4. The fractographically analytical cause of metal failure was ; first, impact failure, one case, second, fatigue failure, six cases, machining mark(stress liser), four cases type : low consistent cyclic fatigue failure irregular cyclic fatigue failure third, stress corrosion crack, one case. 5. 316L Stainless Steel has good resistance to corrosion. However, when its peculiar surface film is destroyed by fretting, it shows pitting corrosion. This is, perhaps, the main cause of metal failure. 6. It is possible that mechanical injury occured in implants during the manufacturing of implants or that making a screw hole is the main cause of metal failure.