• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.2
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• pp.176-183
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• 2021

This study aimed to analyze the preoperative factors of immature first molars treated with vital pulp therapy and to find out their correlation in pediatric patients. From May 2014 to January 2020, 523 patients and 1,242 immature first molars were investigated. Factors including age, sex, tooth location, Molar-incisor hypomineralization (MIH), caries cavity location, and history of previous restoration were evaluated. As a result of the study, the vital pulp therapy group had 5.56 times more MIH, 3.39 times more mesial cavities, and 8.73 times more distal cavities. In order to avoid vital pulp therapy in immature first molar, early diagnosis and active management of MIH and preventive treatment of mesial and distal caries are necessary after its immediate eruption.

• The Journal of the Korean dental association
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• v.57 no.3
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• pp.149-160
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• 2019

Atrophic alveolar ridge of maxillary anterior area is commonly observed after the extraction of teeth in patients with severely compromised periodontal disease, causing difficulties with implant placement. Successful esthetics and functional implant rehabilitation rely on sufficient bone volume, adequate bone contours, and ideal implant positioning and angulation. The present case report categorized the ridge augmentation techniques using guided bone regeneration (GBR) on the maxillary anterior site by Seibert classification. Case I patient presented for implant placement in the position of tooth #11. The alveolar ridge was considered a Seibert classification I ridge defect. Simultaneous implant placement and GBR were performed. Eight months after implantation, clinical and radiological examinations were performed. Case III patient presented with discomfort due to mobility of the upper maxillary anterior site. Due to severe destruction of alveolar bone, teeth #11 and #12 were extracted. After three months, the alveolar ridge was considered a Seibert classification III ridge defect. A GBR procedure was performed; implantation was performed 6 months later. Approximately 1-year after implantation, clinical and radiological examinations were performed. During the whole treatment period, healing was uneventful without membrane exposure, severe swelling, or infection in all cases. Radiographic and clinical examinations revealed that atrophic hard tissues and buccal bone contour were restored to the acceptable levels for implant placement and esthetic restoration. In conclusion, severely resorbed alveolar ridge of the maxillary anterior area can be reconstructed with ridge augmentation using the GBR procedure so that dental implants could be successfully placed.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.182-188
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• 2019

A proper vertical dimension and a harmonious occlusal plane are essential to satisfy a patient esthetically and functionally. A maxillomandibular occlusal vertical dimension is determined by the elevators which repeatedly contracts to a certain length, and a tooth location is determined by a maxillomandibular vertical dimension. The patient of this case came in with the incongruity of the lips and the occlusal plane. The result of clinical test showed the lack of length of the lower anterior due to the reduction of vertical dimension, the deep overbite of anterior, the excessive attrition of anterior, and the incongruity of occlusal plane. After the diagnostic wax-up, the temporary restoration was installed, and final prosthesis was installed after 6 months. As a result, the patient obtained a functionally and esthetically satisfying result.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.134-145
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• 2021

In the case of excessively worn dentition, there is often insufficient space for the prosthesis, and if physiologically acceptable, the prosthesis can be fabricated by increasing the vertical dimension of occlusion. Various methods have been introduced to determine the vertical dimension of occlusion. Clinicians have to choose a method that can comfort the patient among several methods. A removable appliance can be used as a reversible method to ensure that the determined vertical dimension of occlusion does not cause physiological problems. When making impressions of many teeth, it is often difficult to make accurate impressions at once. In this case, after making an accurate impression of the individual teeth, a transfer coping was made and a pickup impression was taken in the oral cavity to create a master cast. In this case, a fixed partial denture was fabricated and full mouth rehabilitation was performed by increasing the vertical dimension of occlusion in a patient with excessively worn dentition and lack of space for restoration. As a result of follow-up of the patient for 7 years, satisfactory results were obtained both esthetically and functionally.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.126-133
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• 2021

Axial displacement of an implant-supported prosthesis is frequently reported in clinical and laboratory studies. However, limited information is available about the behavior of the axial displacement of implant-supported prostheses functioning in intraoral situations. The present case report evaluated the three-dimensional displacement of posterior single implant-supported prostheses in 2 different patients. Internal connection type implants were placed, and screw and cement-retained prosthesis (SCRP) type prosthesis were delivered after an appropriate healing period. Intraoral digital scans were performed using an intraoral scanner (Cerec Omnicam, Dentsply Sirona, USA) on the day of crown delivery and one week, one month, and one year after delivery. The amount of 3-dimensional displacement of the prosthesis was evaluated by using a digital inspection software (Geomagic Control X, 3D systems, USA). The axial displacement of implant-supported prosthesis occurred in both patients. Furthermore, the amount of displacement increased over time.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.31 no.2
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• pp.47-55
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• 2022

Food impaction due to proximal space opening after implant restoration is a very common phenomenon in patients who have implant prosthesis. This occurs because the movement mechanism between the implant and the tooth is different, and it occurs about 30-60% over time. Contributing factors include the arch (mandible), region (posterior teeth), adjacent teeth (non-vital teeth), and antagonist teeth (natural teeth or implants), etc. While this phenomenon cannot be prevented, efforts should be made to minimize it. In order to have an ideal proximal contact as much as possible, the concave shape or the prominent lower proximal shape should be modified to create a symmetrical proximal shape. with the buccal dentate in the upper third height should be adjusted. Other conditions should be modified so that the heights of the marginal ridges are similar. Since an irregular occlusal plane is a cause of poor prognosis, food impaction should be minimized by restoring the ideal occlusal plane by correcting the extruded antagonist and reduction of the disto-buccal cusp.

• Korean Journal of Materials Research
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• v.33 no.8
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• pp.337-343
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• 2023

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals) ceramics have excellent mechanical properties including high fracture toughness, good abrasion resistance as well as chemical and biological stability. As a result, they are widely used in mechanical and medical components such as bearings, grinding balls, and hip implants. In addition, they provide excellent light transmittance, biocompatibility, and can match tooth color when used as a dental implant. Recently, given the materials' resemblance to human teeth, these ceramics have emerged as an alternative to titanium implants. Since the introduction of CAD/CAM in the manufacture of ceramic implants, they've been increasingly used for prosthetic restoration where aesthetics and strength are required. In this study, to improve the surface roughness of zirconia implants, we modified the 3Y-TZP surface with a biocomposite of hydroxyapatite and forsterite using room temperature spray coating methods, and investigated the mixed effect of the two powders on the evolution of surface microstructure, i.e., coating thickness and roughness, and biological interaction during the in vitro test in SBF solution. We compared improvement in bioactivity by observing dissolution and re-precipitation on the specimen surface. From the results of in vitro testing in SBF solution, we confirmed improvement in the bioactivity of the 3Y-TZP substrate after surface modification with a biocomposite of hydroxyapatite and forsterite. Surface dissolution of the coating layer and the precipitation of new hydroxyapatite particles was observed on the modified surface, indicating the improvement in bioactivity of the zirconia substrate.

• Restorative Dentistry and Endodontics
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• v.48 no.2
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• pp.13.1-13.11
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• 2023

Objectives: Natural extracts have been investigated as a biomimetic strategy to mechanically strengthen the collagen network and control the biodegradation of extracellular matrix. This study evaluated the effect of epigallocatechin-3-gallate (EGCG) on abfraction lesions prior to the composite resin. Materials and Methods: The sample consisted of 30 patients (aged between 28 and 60 years) with abfraction lesions located in 2 homologous premolars. The teeth were randomly assigned according to dentin treatment: 0.02% EGCG solution or distilled water (control). After enamel acid etching, the solutions were applied immediately for 1 minute. The teeth were restored with Universal Adhesive (3M) and Filtek Z350 XT (3M). Analyzes were done by 2 independent examiners using modified USPHS (retention, secondary caries, marginal adaptation, and postoperative sensitivity) and photographic (color, marginal pigmentation, and anatomical form) criteria at baseline (7 days) and final (18 months). The data analysis used Friedman and Wilcoxon signed-rank tests (α = 0.05). Results: At baseline, all restorations were evaluated as alpha for all criteria. After 18 months, restorations were evaluated as alpha for secondary caries, color, and marginal pigmentation. There was significant difference between baseline and 18 months (p = 0.009) for marginal adaptation and postoperative sensitivity (p = 0.029), but no significant difference were verified between treatments (p = 0.433). The EGCG group had a restoration retention rate of 93.3%, while the control group had 96.7%. Conclusions: The application of EGCG solution on abfraction lesions did not significantly influence the survival of the restorations based on clinical and photographic criteria.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.209-222
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• 2011

Missing anterior teeth can be replaced using any of a number of methods. Patients may choose to replace missing teeth with a prosthesis that is either removable, fixed, or retained with implants. For patients faced with financial, anatomical, and/or esthetic limitations, the edentulous region can be restored successfully and esthetically with a properly designed and fabricated rotational path RPD. The rotational path RPD is a partial removable dental prosthesis that incorporates a curved, arcuate, or variable path of placement allowing one or more of the rigid components of the framework to gain access to and engage an undercut area. The rigid retainer must gain access to the infrabulge portion of the tooth by rotating into place. Either a minor connector or proximal plate provides retention through its intimate contact with a proximal tooth surface. A specially designed dovetails or asymmetric rest seats provides support and embracing effects. Correctly designed and fabricated rotational path RPD can provide improved esthetics, cleanliness, and retention. But rotational path RPDs are technique sensitive since the rotational path RPD has little margin of laboratory error that rigid retainers cannot be adjusted like conventional clasps can, RPD framework must be remade once the retention is lost. The sufficient understanding of the concept for the rotational path RPD is required for clinically successful treatment. This clinical report describes in detail the theoretical, laboratory considerations and the treatment of a patient with an anterior maxillary edentulous area treated by an AP path rotational RPD that had a difficulty in long term maintenance and describes another clinical case in which more reasonable treatment procedures were approached after analyzing the former case.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.249-257
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• 2007

State of problem : The use of zirconium oxide all-ceramic material provides several advantages, including a high flexural strength(>1000MPa) and desirable optical properties, such as shading adaptation to the basic shades and a reduction in the layer thickness. Along with the strength of the materials, the cementation technique is also important to the clinical success of a restoration. Nevertheless, little information is available on the effect of different surface treatments on the bonding of zirconium high-crystalline ceramics and resin luting agents. Purpose : The aim of this study was to test the effects of surface treatments of zirconium on shear bond strengths between bovine teeth and a zirconia ceramic and evaluate differences among cements Material and methods : 54 sound bovine teeth extracted within a 1 months, were used. They were frozen in distilled water. These were rinsed by tap water to confirm that no granulation tissues have left. These were kept refrigerated at $4^{\circ}C$ until tested. Each tooth was placed horizontally at a plastic cylinder (diameter 20mm), and embedded in epoxy resin. Teeth were sectioned with diamond burs to expose dentin and grinded with #600 silicon carbide paper. To make sure there was no enamel left, each was observed under an optical microscope. 54 prefabricated zirconium oxide ceramic copings(Lava, 3M ESPE, USA) were assigned into 3 groups ; control, airborne-abraded with $110{\mu}m$ $Al_2O_3$ and scratched with diamond burs at 4 directions. They were cemented with a seating force of 10 ㎏ per tooth, using resin luting cement(Panavia $F^{(R)}$), resin cement(Superbond $C&B^{(R)}$), and resin modified GI cement(Rely X $Luting^{(R)}$). Those were thermocycled at $5^{\circ}C$ and $55^{\circ}C$ for 5000 cycles with a 30 second dwell time, and then shear bond strength was determined in a universal test machine(Model 4200, Instron Co., Canton, USA). The crosshead speed was 1 mm/min. The result was analyzed with one-way analysis of variance(ANOVA) and the Tukey test at a significance level of P<0.05. Results : Superbond $C&B^{(R)}$ at scratching with diamond burs showed the highest shear bond strength than others (p<.05). For Panavia $F^{(R)}$, groups of scratching and sandblasting showed significantly higher shear bond strength than control group(p<.05). For Rely X $Luting^{(R)}$, only between scratching & control group, significantly different shear bond strength was observed(p<.05). Conclusion : Within the limitation of this study, Superbond $C&B^{(R)}$ showed clinically acceptable shear bond between bovine teeth & zirconia ceramics regardless of surface treatments. For the surface treatment, scratching increased shear bond strength. Increase of shear bond strength by sandblasting with $110{\mu}m$ $Al_2O_3$ was not statistically different.