• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.359-371
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• 2007

Recently, many studies were reported accurate analysis of facemask effect due to the development of the personal computers and computer programs. The aim of this study is appropriate protraction direction of facemask using finite element study with computer aided design and computer aided measurement. The construction of the three dimensional FEM was based on the computer tomography(CT) scans of 13.5 year-old male subject. Protraction force of 500 mg was applied at 0, 30, 60 and 90 degrees downwards to the Frankfort horizontal plane, and maxillary displacement and stress distribution were measured. When 60 degree force was applied, it showed forward movement of premolar roots area and downward movement of anterior nasomaxillary area, and others showed clockwise rotation movement of the nasomaxillary complex. Finally, we can produce the protraction of maxillary bone without rotation of maxilla about 60 degrees.

• Imaging Science in Dentistry
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• v.33 no.1
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• pp.15-20
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• 2003

Purpose : To investigate the reproducibility of the conventional and digital radiographs to determine the depth of approximal root cavities. Materials and Methods : A total of 80 artificial root cavities were prepared in the approximal surfaces of premolars, maxillary and mandibular molars. Standardized radiographs were taken at the baseline (0° horizontal and 0° vertical) and at a horizontal angulation of 10° in both mesial and distal directions. Radiographic cavity depths were measured by both conventional and digital radiographs. Results: At 0° horizontal angulation, no statistically significant differences could be determined between the results of conventionally and digitally determined radiographic depths with respect to the actual cavity depths in all premolar, maxillary, and mandibular molar groups. All conventional and digital radiographic depths at both 10° mesial and distal angulations showed statistically significant increases in depth compared to the actual cavity depths (p < 0.05), with the exception of digital radiographic depth at 10° mesial angulation for premolars. There were no statistically significant differences between conventional and digital radiographic depths for all groups. Conclusion: The present study suggests that both conventional and digital radiographs provide reproducible assessment of the depth of the approximal root cavity. But horizontal X-ray beam movements are likely to result in increase in radiographic cavity depth.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.51-60
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• 2006

Gingival recession is clinically manifested by an apical displacement of the gingival tissue and dentin hypersensitivity is often used to describe a painful condition in which exposed dentin is unduly sensitive to intraoral stimuli. The objects of this study were primarily to investigate the prevalence and distribution of gingival recession and hypersensitivity and secondarily to determine whether a relationship exists between gingival recession and hypersensitivity. The study population was 195 patients (102 males, 93 females) who were attended the department of periodontology, Pusan National University Hospital. 189 patients exhibited gingival recession at least more than 1 tooth, the prevalence was 96.9%. The maxillary and mandibular first premolar and mandibular incisors had the highest prevalence. The majority of patients (139 patients, 71.3%) were diagnosed as having dentin hypersensitivity. Dentin hypersensitivity was determined to 3 seconds application of cold air to the exposed root surface after isolating the test tooth and was commonest in maxillary and mandibular first premolars and mandibular incisors. Relationship between recession and hypersensitivity was analyzed using chi-square test (p=0.05), significant relation (p=0.000) was existed. Gingival recession was more severe, the prevalence of hypersensitivity was higher.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.3
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• pp.544-556
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• 1997

All ceramic restorations except In-Ceram Alumina system gave a good esthetics and an exellent marginal fidelity. The flexural strength of them had about 150MPa, so the indication is only single crown. By using In-ceram Alumina System(450Mpa), it is thought to be possible to construct bridge for its high flexural strength. But the prognosis is unclear, The purposes of this study are to clear short term prognosis of In-Ceram bridge restorations, to elucidate its clinical significance. Among 22 In-Ceram Bridge restored in our department, 11 In-Ceram bridges with follow up were used. The period of placement is from 1 to 18 months. The results were as follows : 1. Among follow up 11 bridges, 2 bridges were fractured. One is 4 unit in maxillary lateral incisors, the other is 3 unit bridge in maxillary canine and premolar. Including 11 bridge without follow up, failure rate is very low(2/22). 2. The fracture sites are connector areas between abutment and pontic. To maintain In-Ceram bridge for long term period, it is needed to remove the nonphysiologic occlusal force and to have sufficient thickness of alumina core. For estabilishing clinical use of In-Ceram bridges, it is thought to need clinical research during long term period.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.687-698
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• 2000

The purpose of this study was to evaluate the changes of skeletodental patterns during Class II treatment and its retention period. Forty two patients of Class II malocclusion, which was treated with nonextraction or first premolar-extraction were selected and their lateral cephalograms were examined in this study. Various skeletodental changes in lateral cephalograms of pre-treatment, post-treatment and retention were measured by superimposition in reference to the cranial base for jaws, the palatal plane for maxillary teeth, and mandibular plane for mandibular teeth. The data were analyzed by paired t-test. In this study, occlusal plane showed the significant anterior downward steepening after active treatment, and remained during retention period. In the nonextraction group, maxillary incisors were retracted and extruded during treatment. Maxillary molars were extended, and mandibular molar were uprighted, with no mesial movement. In the extraction group, both maxillary and mandibular incisors were retracted and extruded. Maxillary molars were extruded and moved mesially, and mandibular molars were extruded and moved mesially with no mesial tilting. During retention period in both groups, there were tendencies of labial tipping of maxillary incisor, and mesial tipping of maxillary and mandibular molar. But the changes were not significant and most of teeth showed no change in vortical and horizontal direction.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.1
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• pp.60-69
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• 2005

Orthopedic rapid maxillary expansion(RME) has been a common treatment modality used to widen narrow maxillae in young children. However, since more skeletally matured adolescents or adults has closed midpalatal suture, the result of RME was undesirable because of dental tipping with little or no basal skeletal movement and resulted to many other complications. After such treatment, complications often occurred such as alveolar bending, compression of periodontal ligament, extrusion, buccal tipping, and severe relapse. Thus, surgically assisted rapid maxillary expansion(SA-RME) is required, especially for patients over 14 years old, to skeletally release maxillary expansion. We used two methods of maxillary expansion surgery. Surgically assisted rapid maxillary expansion(SA-RME) & surgically assisted posterior segmental expansion(SA-PSE) were used for narrow maxilla. The study was divided into two groups(SA-RME group and SA-PSE group). SA-RME group was consisted of 2 males and 4 females, and the ages of materials ranged from 15 years to 25 years with a mean of 20.2 years. SA-PSE group was consisted of 1 male and 5 females, and the ages ranged from 13 years to 23 years with a mean of 18.7 years. Dental study models were fabricated before starting the expansion and immediately after the expansion was completed. It was fabricated again 1 month later, 3 months later when the expansion device was removed, and 6 months later after the expansion was completed. A repeated measures analysis of variance(ANOVA) test was applied to assess changes between each groups over time. The amount of expansion and the amount of tipping movement each in both groups were compared by using paired t-test and it was also compared between each subjects within the group by using independent t-test. Both SA-RME and SA-PSE group showed stable results, but SA-PSE group showed statical significance in tipping movement of second premolar. We compared 6 patients who recieved SA-RME with 6 patients who received SA-PSE, and appraised the clinical usefulness.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.3
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• pp.153-159
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• 2019

Purpose: Aims to analyze the occlusal wear patterns in maxillary posterior teeth with palatal side abfractions and study the association between occlusal force and abfractions. Materials and Methods: This study was conducted in a total of 308 teeth from 148 patients with palatal side abfractions in maxillary posterior teeth. The occlusal wears in maxillary premolars and molars with palatal side abfractions were classified and recorded. The classification was done by type of teeth, age, and gender, and in order to evaluate the statistical significance between groups, chi-square test was conducted (${\alpha}=0.05$). Results: Palatal side abfractions in maxillary posterior teeth were observed at the highest frequency in the 1st molars, and in all teeth with palatal side abfractions, more than one occlusal wear was observed. In classification by type of teeth, by age, and by gender, the occlusal wears in teeth with palatal side abfractions were observed at high frequency in cuspal inclined plane, central fossa, and marginal ridge, and there was a statistical significance (P < 0.05). Conclusion: Palatal side abfractions were observed at the highest frequency in maxillary 1st molars, and in all maxillary posterior teeth where palatal side abfractions were found, the occlusal wears were observed. And the occlusal wears were observed at high frequency in cuspal inclined plane, central fossa and marginal ridge. Such results show that abfraction is associated with occlusal force.

• The korean journal of orthodontics
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• v.49 no.2
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• pp.124-136
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• 2019

Orthodontic treatment is more complicated when both soft and hard tissues must be considered because an impacted maxillary canine has important effects on function and esthetics. Compared with extraction of impacted maxillary canines, exposure followed by orthodontic traction can improve esthetics and better protect the patient's teeth and alveolar bone. Therefore, in order to achieve desirable tooth movement with minimal unexpected complications, a precise diagnosis is indispensable to establish an effective and efficient force system. In this report, we describe the case of a 31-year-old patient who had a labio-palatal horizontally impacted maxillary left canine with a severe occlusal alveolar bone defect and a missing maxillary left first premolar. Herein, with the aid of three-dimensional imaging, sequential traction was performed with a three-directional force device that finally achieved acceptable occlusion by bringing the horizontally impacted maxillary left canine into alignment. The maxillary left canine had normal gingival contours and was surrounded by a substantial amount of regenerated alveolar bone. The 1-year follow-up stability assessment demonstrated that the esthetic and functional outcomes were successful.

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.451-458
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• 2005

Cephalometric superimposition is unable to evaluate tooth movement along the occlusal plane and the errors of photographing and superimposition of the occlusogram is also inevitable. The purpose of the present study was to evaluate the rotational movements of the maxillary posterior teeth following space closure after extraction of maxillary first premolars. using 3D dental images. In 19 adult females. analysis of rotational movements of the maxillary posterior teeth was performed between the initial and final 3D dental images superimposed on the maxillary hard palate. The results showed a diversity of rotational movements of posterior teeth. The causes of various rotational movements may be different rotation of molars in each case at the beginning of treatment. individual characters of the dental arch and tooth morphology. The results of the study indicate that accurate evaluation of rotational movements of posterior teeth following space closure after extraction of premolars using 3D dental images can be obtained through the subdivision of tooth movement during the initial aligning, space closure and finishing stages.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.147-154
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• 2006

Surgical intervention in the posterior maxillary region requires detailed knowledge of maxillary sinus anatomy and the possible anatomical variations. This study evaluated the incidence, location of maxillary sinus septa by using radiographic (panoramic radiography and computed tomography) findings and comparison of panoramic radography with CT in antral anatomical variation. This study was based on data from 70 sinuses in partial dentate maxilla. The sample consisted of 61 patients(25 women and 36 men, with ages ranging between 19 and 77 years and a mean age of $49.4{\pm}11.3$ years) who were being treatment-planned to receive implant-supported restorations. First, the panoramic images were examined for the presence of antral septa by radiologist and examiner who don't know about CT findings. And incidence of antral septa was evaluated using an axial plane of CT image. The incidence of septa was compared between panoramic radiography and CT. The accuracy of the incidence was compared between radiologists and dentists. A total of 20 septa were found in 70 sinuses on CT image and the prevalence of one or more septa per sinus was found to be 28.6%. The assumed incidence of septa on panoramic radiography was $27.6%{\pm}2.2%$ in radiologist and $31.9%{\pm}5.8%$ in dentists. Erroneous diagnosis rate was 11.42% in radiologist and 15.96% in dentists. 40% of antral septa were located in the anterior(premolar) region, 30% of septa were located in the middle(first molar) and posterior(second molar) region separately. Prior to implant placement, it seems appropriate to consider panoramic radiography as a standard radiographic examination and periapical radiographs may be used to complete the findings in regions not sharply depicted in the panoramic radiograph. And cross-sectional imaging should be used in sites with severe bone loss and close proximity of the maxillary sinus.