• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.313-326
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• 2007

With rising prevalency of mouth breathing children caused by developing civilization and increasing pollution, there are many maxillary transverse discrepancy patients with undergrowth of maxilla. For improving this, maxillary mid-palatal suture splitting was often performed. The purpose of this study was to analyse the stress distribution on the craniofacial suture and cranium after rapid maxillary expansion by finite element model. The boy(13Y6M) was chosen for taking computed-tomography for finite element model. Three-dimensional model of maxilla, first premolar, first molar, buccal and lingual part of rapid maxillary expansion were constructed. 1. The alveolar bone adjacent to the first molar and the first premolar that was affected directly by rapid maxillary expansion was displaced laterally approximately 4.04mm at maximum. The force decreased toward anterior region and frontal alveolar bone displaced laterally about 3.18mm. 2. A forward maximum displacement was exhibited at zygomatic process middle region. 3. At maximum, maxillary median part experienced 0.973mm downward repositioning and 0.65mm upward repositioning at lateral alveolar bone. 4. Von mises stress was observed the largest stress distribution around teeth and zygomatic buttress. 5. The largest tensile force was observed around alveolar bone of teeth, while compression force was observed at zygomatic buttress.

• The korean journal of orthodontics
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• v.48 no.3
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• pp.153-162
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• 2018

Objective: The aim of this trial was to compare the alignment efficiency and intermaxillary arch dimension changes of nickel-titanium (NiTi) or copper-nickel-titanium (CuNiTi) round archwires with increasing diameters applied sequentially to the mandibular arch. Methods: The initial alignment phase of fixed orthodontic treatment with NiTi or CuNiTi round archwires was studied in a randomly allocated sample of 66 patients. The NiTi group comprised 26 women, 10 men, and the CuNiTi ($27^{\circ}C$) group comprised 20 women, 10 men. The eligibility criteria were as follows: anterior mandibular crowding of minimum 6 mm according to Little's Irregularity Index (LII), treatment requiring no extraction of premolars, 12 to 18 years of age, permanent dentition, skeletal and dental Class I malocclusion. The main outcome measure was the alignment of the mandibular anterior dentition; the secondary outcome measure was the change in mandibular dental arch dimensions during 12 weeks. Simple randomization (allocation ratio 1:1) was used in this single-blind study. LII and mandibular arch dimensions were measured on three-dimensional digital dental models at 2-week intervals. Results: No statistically significant difference was observed between NiTi and CuNiTi according to LII (p > 0.05). Intercanine and intermolar arch perimeters increased in the CuNiTi group (p < 0.001). Inter-first premolar width showed a statistically significant interaction in week ${\times}$ diameter ${\times}$ application (p < 0.05). Conclusions: The effects of NiTi and CuNiTi round archwires were similar in terms of their alignment efficiency. However, the intercanine and intermolar arch perimeters, and the inter-first premolar width changes differed between groups.

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.55-61
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• 2010

Tooth restoration with implant placement have been interested in modern veterinary dentistry. It is important to reduce the interval between the tooth extraction and the insertion of the implants, to determine the restoration time after implant placement in dogs The aim of the this study was to compare the bone mineral apposition rate of immediately loaded implants with an unloaded control during the early healing state in the artificial extraction mandible. In four Beagles, two premolar sockets (PM2 and PM3) of the both sides of the mandible were installed with a one stage titanium mini-implant with a length of 11 mm and a diameter of 3.37 mm immediately after tooth extraction. Provisional restroration was given to implants, 3 weeks after implant placement in the left side (immediate loading) and 12 weeks in the right side (delayed loading), respectively. Radiographic and histologic examinations were performed. Radiographic evaluation revealed no significant difference between two groups. Bone-implant contact was $47.1{\pm}8.9$ in immediate loading and $50.2{\pm}8.2$ in delayed loading, interthread bone density was $78.7{\pm}10.9$ in immediate loading and $73.1{\pm}15.5$ in delayed loading, and peri-implant bone density was $95.4{\pm}7.1$ in immediate loading and $95.0{\pm}5.2$ in delayed loading, respectively. Three histologic analyses showed no significant difference between delayed and immediate loading. Followed by this study, the immediate loading of implants insterted into fresh extraction sockets after tooth extraction could be considered in veterinary dentistry.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.280-289
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• 2016

Objective: The aim of this study was to analyze tooth movement and arch width changes in maxillary dentition following nonextraction treatment with orthodontic mini-implant (OMI) anchorage in Class II division 1 malocclusions. Methods: Seventeen adult patients diagnosed with Angle's Class II division 1 malocclusion were treated by nonextraction with OMIs as anchorage for distalization of whole maxillary dentition. Three-dimensional virtual maxillary models were superimposed with the best-fit method at the pretreatment and post-treatment stages. Linear, angular, and arch width variables were measured using Rapidform 2006 software, and analyzed by the paired t -test. Results: All maxillary teeth showed statistically significant movement posteriorly (p < 0.05). There were no significant changes in the vertical position of the maxillary teeth, except that the second molars were extruded (0.86 mm, p < 0.01). The maxillary first and second molars were rotated distal-in ($4.5^{\circ}$, p < 0.001; $3.0^{\circ}$, p < 0.05, respectively). The intersecond molar width increased slightly (0.1 mm, p > 0.05) and the intercanine, interfirst premolar, intersecond premolar, and interfirst molar widths increased significantly (2.2 mm, p < 0.01; 2.2 mm, p < 0.05; 1.9 mm, p < 0.01; 2.0 mm, p < 0.01; respectively). Conclusions: Nonextraction treatment with OMI anchorage for Class II division 1 malocclusions could retract the whole maxillary dentition to achieve a Class I canine and molar relationship without a change in the vertical position of the teeth; however, the second molars were significantly extruded. Simultaneously, the maxillary arch was shown to be expanded with distal-in rotation of the molars.

• Imaging Science in Dentistry
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• v.39 no.2
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• pp.81-87
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• 2009

Purpose: To evaluate the anteroposterior length and buccal angle of the anterior loop, and the size and location of the mental foramen using cone beam computed tomography (CBCT). Materials and Methods: 100 CBCT images from 87 adults (43 males and 44 females) ranging in age from 20 to 73 years (average 50 years) with edentulous ridge of the mandibular premolar region were obtained. Axial, sagittal, coronal images were reconstructed from Dental and Block Images of CBCT. The anteroposterior length, shape and buccal angle of the anterior loop, and the size and location of the mental foramen were calculated from reconstructed images of axial, sagittal and coronal CBCT. Results: The anteroposterior length and buccal angle of the mental canal was 4.0${\pm}$1.2mm, 37.8${\pm}$11.60$^{\circ}$respectively. The loop type with straight course was the most common shape of the mental canal. The location of the mental foramen below the apex of the lower second premolar (78%) was the most common. The maximum size of the mental foramen was 4.6${\pm}$1.0 mm in width and 3.0${\pm}$0.6 mm in height. The inner size of the mental canal was 2.6${\pm}$0.6 mm in width and 2.1 mm${\pm}$0.4 mm in height. Conclusion: CBCT is useful to evaluate the anterior loop and mental foramen of the mandibular canal. Safe guideline of 4 mm from the most anterior point of the mental foramen is recommended for implant and surgical treatment. (Korean J Oral Maxillofac Radiol 2009; 39: 81-7)

• Journal of Periodontal and Implant Science
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• v.31 no.3
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• pp.625-631
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• 2001

The anatomic structure around interproximal area plays an important role not only in the natural teeth, but also in the implant. The loss of papilla can lead to cosmetic deformity, phonetic problem, food impaction on the anterior dentition, and masticatory problem, food impaction and proximal caries on the posterior dentition. The purpose of this study was to evaluate the relationship between interdental papilla existence and distance from contact point to alveolar crest in Korean posteior dentition. 45 Korean adult patients(31males, 14 females) participated in this study. Measurements were carreid out total 126 interproximal areas, 18 first premolar, 31 second premolar, 40 first molar, and 37 second molar areas. Papilla index was recorded as suggested by Jemt. Distance between contact point and alveolar crest measrued by Florida $probe^{R}$, after flap elevation. Each distance was measured 10 times by every 0.1mm unit. The results showed that the mean Papilla index 1.37 and mean distance between contact point and alveolar crest was 7.44mm. The correlation between the Papilla index and distance was high negative correlation(Pearson correlation=-0.47), and it was statistically significant(P=0.000) When the distance between contact point and alveolar crest was 5mm, the loss of papilla was appeared almost in half cases. When the distance was 6mm, the papilla loss was present 95%, when 7mm, the papilla loss was 100%.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.793-803
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• 2000

Procedures for treatment of molar furcation invasion defects range from open flap debridement, apically repositioned flap surgery, hemisection, tunneling or extraction, to regenerative therapies using bone grafting or guided tissue regenerative therapy, or a combination of both. Several clinical evaluations using regenerative techniques have reported the potential for osseous repair of treated furcation invasions. Regenerative treatment of maxillary molars are more difficult due to the multiple root anatomy and multiple furcation entrances therefore, purpose of this study was to evaluated histologically self-curing glass-ionomer cement and light-curing glass-ionomer cement as a barrier in the treatment of a bi-furcated maxillary premolar. Five adult beagle dogs were used in this experiment. With intrasulcular and crestal incision, mucoperiosteal flap was elevated. Following decortication with 1/2 high speed round bur, degree II furcation defect was made on maxillary third(P3), forth(P4) and fifth(P5) premolar. 2 month later experimental group were self-curing glassionomer cement and light-curing glassionomer cement. After 4, 8 weeks, the animals were sacrificed by vascular perfusion. Tissue block was excised including the tooth and prepared for light microscope with Gomori's trichrome staining. Results were as follows. 1. In all experiment group, there were not epithelial down growth and glass ionomer cement were encapsulated connective tissue. 2. In 4 weeks experiment I group slighly infiltrated inflammatory cells but not disturb the new bone or new cementum formation. 3. In 8 weeks, experiment groups I, II were encapsulated fine connective tissue. 4. Therefore glass-ionomer cement filling to the grade III maxillary furcations with multiple root anatomy and multiple furcation entrances were possible clinical methods and this technique is useful method for Maxillary furcation involvement.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.218-231
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• 2005

Statement of problem. In the partially edentulous patients, removable partial dentures have been working as a important treatment modality. Clasps, a kind of direct retainers, received some amount of stresses during the insertion and removal of partial denture on the abutment tooth. Purpose. The study is to investigate stresses of the different clasps. Material and methods. In order to investigate the degree of stresses, maxillary partial edentulism (Kennedy Class II modification I) was assumed and removable partial dentures were designed on it with three kinds of metallic materials; cobalt-chromium alloy, type IV gold alloy and commercially pure (c.p.) titanium. Aker's clasp was applied on the left second molar. RPA (mesial rest-proximal plate-Aker's) clasp was on the left first premolar and wrought wire clasp was on the right first premolar. Three dimensional, non-linear, dynamic finite element analysis method was run to solve this process. Results. 1. Cobalt-chromium alloy had the highest von Mises stress value and c.p. titanium had the lowest one irrespective of the types of clasps. 2. In the Aker's clasps, stress on the retentive tips was shown shortly after the appearance of stresses of the middle and minor connector areas. These time lag was much shorter in the RPA clasps than in the Aker's clasp. 3. In general. retentive tips of wrought wire clasps had much less amount of stress than other clasps. Conclusion. The amount of stress was the highest in the RPA clasp and the lowest in the wrought wire clasp, in general.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.15 no.1
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• pp.75-83
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• 1985

Bitewing and periapical radiographic techniques are used in clinical and epidemiological studies to assess crestal alveolar bone levels. The purpose of the present study investigated relationships between these techniques by assessing alveolar crest location at the same site. Bitewing and periapical radiographs were available from posterior quadrants of 120 subjects. The distance from cemento-enamel junction to the alveolar crest (CEJ -CR) was measured for each proximal surface from the distal of the cuspid to the distal of the second molar. Data were arranged according to the proximal surface examined, and bitewing and periapical measurements were compared using paired tests. The obtained results were as follows; 1. In maxilla, a significant t ratio with a P value of 0.05 or less was reached for 78% and in mandible reached for 39%. 2. Pearson correlations were calculated 32 surfaces (89%) had values below 0.70 and so, data obtained by these techniques can not be used interchangeably on an individual or group basis. 3. In situations where the periapical measure was greater than the bitewing, it ranged up to 20.7% greater with a mean 9.8%. Where the bitewing was greater than periapical, it ranged up to 51. 9% greater, with a mean 18.2%. 4. The percentage difference was greater in maxillary posterior areas than in mandibular molar, premolar areas. A lower prevalence of significant differences was attributed to relatively more simple root and favorable radiographic conditions in mandibular molar and premolar areas. 5. The anatomical limitations imposed on periapical radiographic technique, most often result in somewhat foreshortened radiographic images. This situation would tend to be accentuated by the anatomical restrictions of the hard palate. 6. Consequently, since the significant differences frequently exist between measurements obtained from bitewing and periapical techniques, it is important to define which technique is used.

• Journal of Periodontal and Implant Science
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• v.39 no.1
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• pp.17-26
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• 2009

Purpose: The non-carious cervical lesion(NCCL) is a loss of tooth structure at the neck of affected teeth that is unrelated to tooth caries. The reported prevalence of NCCL varies from 5% to 85%. Prevalence and severity of lesions have been found to increase with age. They are becoming more significant as people live longer and become more aware of the importance of oral health. The purposes of this study were first, to examine the periodontal conditions associated with NCCL, and second, to investigate the clinical effects of class V restorations of NCCL on periodontal tissues. Materials and methods: The sample size was 982 teeth of 50 subjects(25 male, mean age $52{\pm}7$) who were seen at the Department of Periodontology, Pusan National University Hospital. At the baseline examination, clinical periodontal parameters were measured. After the initial examination, 24 patients who were absent from hypersensitivity were selected. The teeth with NCCL were randomly divided into the test and control groups. The teeth in the test group were restored with flowable resin; the control teeth were not restored. Six months later, the clinical examinations were repeated. The data were analyzed using the SPSS program. Results: The results were as follows: 1) NCCL occurred on 45.8% of examined teeth. The percentage of affected teeth was higher in maxillary and premolar teeth. 2) The shallow saucer type was the most common. 3) Teeth with NCCL had more gingival recession, lower attachment level, and higher incidences of bleeding on probing(BOP) and plaque than NCCL-free teeth. 4) Six months later, gingival recession, attachment level, the percentages of BOP and plaque in the test group were lower than in the control group(p<0.05). Conclusion: NCCLs were more found in maxillary teeth, especially in premolar teeth. The results suggest that the restoration of NCCL could affect some periodontal parameters favorably.