• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.35.1-35.9
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• 2022

Although the success rates of microsurgery and micro-resurgery are very high, the influence of a recurrent perforation combined with radicular cyst remains unclear. A 21-year-old white female patient had a history of root perforation in a previously treated right maxillary lateral incisor. Analysis using cone-beam computed tomography (CBCT) revealed an extensive and well-defined periapical radiolucency, involving the buccal and palatal bone plate. The perforation was sealed with bioceramic material (Biodentine) in the pre-surgical phase. In the surgical phase, guided tissue regeneration (GTR) was performed by combining xenograft (lyophilized bovine bone) and autologous platelet-rich fibrin applied to the bone defect. The root-end preparation was done using an ultrasonic tip. The retrograde filling was performed using a bioceramic material (Biodentine). Histopathological analysis confirmed a radicular cyst. The patient returned to her referring practitioner to continue the restorative procedures. CBCT analysis after 1-year recall revealed another perforation in the same place as the first intervention, ultimately treated by micro-resurgery using the same protocol with GTR, and a bioceramic material (MTA Angelus). The 2-year recall showed healing and bone neoformation. In conclusion, endodontic micro-resurgery with GTR showed long-term favorable results when a radicular cyst and a recurrent perforation compromised the success.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.320-327
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• 2009

Statement of Problem: Although many efforts have been continually made to estimate long term prognosis of removable partial dentures, the complication of removable partial dentures was still found because of inaccurate fabrication procedure and improper maintenance care. Purpose: The purpose of this study was to evaluate the clinical status of removable partial dentures. Material and methods: A total of 112 individuals with 153 removable partial dentures (35 - 87 years, 64 women and 48 men) were examined by intra-oral examination, diagnostic cast and radiographic examination. Results and conclusion: The results of this study were as follows: 1. Length of service of removable partial dentures was $5.3{\pm}4.3$ years (mean), 4.0 years (median). 2. A total of 45 removable partial dentures were considered failures. The loss of 18 abutments of 369 was founded. 3. Type of arch, Kennedy classification and type of opposite dentition were found to have no influence on longevity and success rate of removable partial dentures (P > .05). 4. Most common major connector was the palatal plate in maxilla and the number of lingual bar and linguoplate designed in mandible were similar. 5. The circumferential type retainer was the most commonly used retainer. 6. Sixty-three percent of the class I and II removable partial dentures incorporated indirect retention into the design. 7. Approximately 81% of the removable partial dentures had at least one defect. Excessive wear of posterior teeth (27.9%), lack of integrity (23.2%), lack of stability (22.6%) were frequent defects of removable partial dentures.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.464-474
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• 2009

To distalize the maxillary molars, the traditional techniques such as extra-oral traction, Wilson distalizing arches, removable spring appliances and Schwarz plate-type appliances have been used. But, these need considerable patient cooperation. For minimal patient compliance, many practitioners use the pendulum appliances. Several clinical studies demonstrated pendulum is effective molar distalization appliance in the growing patient(using the premolars and the palate as anchorage). But unfortunately, maxillary anterior teeth also shift mesially as the molar moves distally. As a result anchorage loss is occurred. To overcome these disadvantages, we used bone-supported pendulum, combined the conventional pendulum with Skeletal Anchorage System(SAS). The miniscrew was implanted in the anterior paramedian region of the median palatal suture, which has comparatively sufficient bone thickness and is low risk to damage on the dental follicles. We report three cases, using bone-supported pendulum for the maxillary molar distalization in children. After treatment, we find out anchorage stability, minimal unfavorable anterior tooth movement and sufficient molar distalization.

• Journal of Periodontal and Implant Science
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• v.49 no.5
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• pp.299-309
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• 2019

Purpose: To analyze the ridge profile of the anterior maxilla using cone-beam computed tomography and to assess the clinical significance of the ridge profile by performing virtual implant placement. Methods: Thirty-two cone-beam computed tomography scans of anterior maxillae were included. For each tooth, a vertical line was made along the longitudinal axis, and 3 horizontal lines at 1-, 3-, and 5-mm levels below the labial bone crest were drawn perpendicularly to the vertical reference. At these levels, the thickness of the alveolar ridge (RT), and the labial (LT) and palatal bone plate (PT) were measured. Then, virtual implant placement using standard and tapered implants was performed. A generalized linear mixed model was used for statistical analysis. Results: The teeth were located labially based on the proportion of LT and PT with respect to RT. At the 1-mm level, the value of LT was between $1.0{\pm}0.4mm$ for central incisors and $1.3{\pm}0.6mm$ for canines. A large number of teeth had area(s) with less than 1-mm-thick labial bone between the 1- and 5-mm levels below the crest. The mean PT was generally thicker than the LT in all tooth types. The greatest mean value of labial concavity was observed for canines, compared to other tooth types. Men had a greater RT than did women, but had a comparable LT. Less apical fenestration was observed when tapered implants were used. Conclusions: Most teeth in the anterior maxilla had a thin labial bone plate, with no significant difference between sexes. Tapered implants may be advantageous for the anterior maxilla.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.88-94
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• 2020

Purpose: The purpose of this study was to analyze the sagittal root position of maxillary anterior teeth and report the frequency of each classification in Korean for immediate implant placement. Materials and Methods: A retrospective review of cone-beam computed tomography (cone-beam CT) images was conducted on 120 patients (60 male and 60 female) who fulfilled the inclusion criteria. After reorientation of the axis, cone-beam CT images were evaluated and the relationship of the sagittal root position (SRP) of the maxillary anterior teeth to its associated osseous housing was recorded. Class I, II, and III were classified respectively when the root was positioned on the labial, central, and palatal aspect of the alveolar bone. Class IV was the position that at least two thirds of the root is engaging both the labial and palatal cortical plates. Then, the angulation of the root axis and the alveolar bone axis was measured. Descriptive statistics and Kruskal-Wallis test were used to compare the angulation according to the root position and SRP class. Results: The frequency distribution of sagittal root position of maxillary anterior teeth indicated that 81.1%, 10.3%, 1.9%, and 6.7% were classified as Class I, II, III, and IV, respectively. The sagittal angulation at approximately 77.5% of central incisor, lateral incisor, and canine was < 20 degrees, but the angle at more than 42.7% of canine was ≥ 20 degrees. Within the class, the angulation was statistically significantly greater in Class I (16.19) compared to Class II (8.72) and Class III (9.93), and smaller in Class IV (3.79). Conclusion: Within the limitation of this study, a majority of the maxillary anterior roots were positioned close to the buccal cortical plate. However, some roots have very thin alveolar bone and sagittal angulation larger than 30 degrees. Therefore, cone-beam CT analyses of the sagittal root position and the sagittal angulation are recommended for the selection of the appropriate dental implant treatment approach.

• The korean journal of orthodontics
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• v.14 no.2
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• pp.203-215
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• 1984

This experiment was performed to explore the effect of electric currents and orthodontic forces on bone $PGE_2$ content and orthodontic tooth movement on cats. Stainless steel electrodes were connected a power pack consisting of five miniature batteries, a transistor, and a resistor. The current $(10{\pm}2{\mu}A)$ was provided by a constant source encased in a palatal acrylic plate. In first experiment, the cathode was placed mesial to the right maxillary canine tooth and the anode was positioned distal to the tooth, Sham electrodes were placed new the left cuspid, to serve as control. Nine cats were divided into three groups evenly. Groups of three animals were treated with electric currents only-for 1, 3 and 7 days, respectively. In second experiment, electric currents and the orthodontic forces of about 80 gm were applied to the right maxillary canine, and the orthodontic forces only were applied to the left maxillary canine. 3 groups of three cats each were treated in this experiment-for 1, 3 and 7 days, respectively. Alveolar bone samples were obtained from sites of tension and compression as well as from contralateral sites. Bone samples were extracted by homogenization in $40\%$ ethanal. The supernatant partitioned twice with 2 volumes of petroleum ether to remove neutral lipids and the aqueous supernatant partitioned in ethyl acetate. After drying the solvent, $PGE_2$ was measured by radioimmunoassay technique. The obtained results were as follows. 1. Teeth treated with combined force and electricity moved faster than those treated with force alone. 2. Alveolar bone $PGE_2$ content of electric stimulation was increased at both electrodes. 3. Alveolar bone $PGE_2$ content of mechanical stimulation at compression sites was gradually increased at all time period. At tension site, $PGE_2$ content increased after 1 day of mechanical stimulation remained elevated at all time period. 4. Alveolar bone $PGE_2$ content of compression sites was increased more than that of tension sites from mechanical stimulation as well as electrical stimulation.

• 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.