• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.559-568
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• 1996

The purpose of this study was to evaluate the micro leakage of composite resin when various phosphoric acid agents were used to etch the enamel and dentin. In this study, class V cavities were prepared on the buccal surfaces of fourty extracted human molar teeth, and they were randomly assigned into 4 groups with 10 teeth. The cavities of each groups were etched with 10%, 32%, 35% and 37% phosphoric acids for 15 seconds, washed and dried and the cavities were restored with composite resin after application of the adhesive. The specimens were immersed in 2% methylene blue solution for 3 days. And then, the specimens were sectioned buccoligually. Degree of dye penetration at tooth-restoration interfaces was examined by Inverted Metallurgical Microscope at the occlusal and gingival margins. The result were as follows : 1. The degree of microleakage at occlusal and gingival margin in all group was statistically difference among 10% and 35% (P<0.01), 10% and 37% (P<0.01), 32% and 35% (P<0.05) and 32% and 37% (P<0.05) acid concentrations, but was not statistically difference between 10% and 32%, 35% and 37% acid concentrations (P>0.05). The degree of microleakage was showed to dimish with increase of acid concentration. 2. The degree of microleakage at the occlusal margin was statistically significant difference among 10% and 32%,10% and 35%, 10% and 37% acid concentrations(P<0.05). The degree of microleakage among 32% and 35%, 32% and 37% and 32% and 37% acid concentrations was not statistically significant difference. 3. In comparison of microleakage at the gingival margin, the degree of microleakage above 32% acid concentration was not showed less than 10% acid concentration (P>0.05). In comparison of 32%, 35%, 37% acid concentrations, the degree of microleakage at 35% and 37% acid concentrations was showed less than 32% acid concentration(P<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.1
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• pp.111-118
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• 2019

Post-endodontic restorations are both important and challenging for clinical success in endodontically treated posterior teeth. Several options have been proposed to restore endodontically treated molars. In pediatric dentistry, restoration using conventional single crowns, especially for partially erupted molars with insufficient retentive tooth structure, has proven to be difficult. However, the endocrown presents a conservative and esthetic restorative alternative to conventional crowns with post-and-core, as it acquires additional retention within the pulp chamber. The tooth preparation consists of a circular, equigingival, butt-joint margin and a central retention cavity in the pulp chamber that helps to construct both the crown and core as a single unit. This case report describes the esthetic and conservative endocrown restorations of erupting permanent first molars with extensive coronal destruction.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.91-99
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• 2022

Severely worn dentition causes various complications such as loss of tooth structure, discoloration, pulp complications and loss of function and aesthetics. In this case, the patient showed particularly severe attrition in the anterior teeth and lack of space for restoration. The amount of vertical dimension was determined based on the diagnostic wax up, and the patient's adaptation was evaluated by using a removable occlusal splint for 6 weeks. Thereafter, the coordination of the muscular nervous system, aesthetics, temporomandibular joint were re-evaluated for 3 months by restoring the fixed provisional restoration. Through the above treatment process, the final restoration was completed with full mouth fixed prosthesis using monolithic zirconia, and functionally and aesthetically stable results were obtained.

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.29.1-29.11
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• 2021

Objectives: This study was conducted to compare the post-fracture survival rate of endodontically treated molar endodontically treated teeth (molar ETT) restored with resin composites or crowns and to identify potential risk factors, using a retrospective cohort design. Materials and Methods: Dental records of molar ETT with crowns or composite restorations (recall period, 2015-2019) were collected based on inclusion and exclusion criteria. The incidence of unrestorable fractures was identified, and molar ETT were classified according to survival. Information on potential risk factors was collected. Survival rates and potential risk factors were analyzed using the Kaplan-Meier log-rank test and Cox regression model. Results: The overall survival rate of molar ETT was 87% (mean recall period, 31.73 ± 17.56 months). The survival rates of molar ETT restored with composites and crowns were 81.6% and 92.7%, reflecting a significant difference (p < 0.05). However, ETT restored with composites showed a 100% survival rate if only 1 surface was lost, which was comparable to the survival rate of ETT with crowns. The survival rates of ETT with composites and crowns were significantly different (97.6% vs. 83.7%) in the short-term (12-24 months), but not in the long-term (> 24 months) (87.8% vs. 79.5%). Conclusions: The survival rate from fracture was higher for molar ETT restored with crowns was higher than for ETT restored with composites, especially in the first 2 years after restoration. Molar ETT with limited tooth structure loss only on the occlusal surface could be successfully restored with composite restorations.

• The korean journal of orthodontics
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• v.53 no.4
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• pp.254-263
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• 2023

Objective: The evidence on the accuracy of bite registration using intraoral scanners is sparse. This study aimed to develop a new method for evaluating bite registration accuracy using intraoral scanners. Methods: Two different types of models were used; 10 stone models and 10 with acrylic resin teeth. A triangular frame with cylindrical posts at each apex (one anterior and two posteriors) was digitally designed and manufactured using three-dimensional (3D) printing. Such a structure was fitted in the lingual space of each maxillary and mandibular model so that, in occlusion, the posts would contact their opposing counterparts, enforcing a small interocclusal gap between the two arches. This ensured no tooth interference and full contact between opposing posts. Bite registration accuracy was evaluated by measuring the distance between opposing posts, with small values indicating high-accuracy. Three intraoral scanners were used: Medit i500, Primescan, and Trios 4. Viewbox software was used to measure the distance between opposing posts and compute roll and pitch. Results: The average maximum error in interocclusal registration exceeded 50 ㎛. Roll and pitch orientation errors ranged above 0.1 degrees, implying an additional interocclusal error of around 40 ㎛ or more. The models with acrylic teeth exhibited higher errors. Conclusions: A method that avoids the need for reference hardware and the imprecision of locating reference points on tooth surfaces, and offers simplicity in the assessment of bite registration with an intraoral scanner, was developed. These results suggest that intraoral scanners may exhibit clinically significant errors in reproducing the interocclusal relationships.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.32 no.2
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• pp.36-45
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• 2023

The aesthetic appearance of the incisors is essential for a natural and healthy smile, and it is also an important factor for confidence in interpersonal relationships. If there is crowding or protrusion of the anterior teeth, root canal treatment and excessive tooth removal are often required to resolve it in a short period of time. However, it is difficult to achieve sustainable aesthetic results. In this case, orthodontic treatment will be necessary to preserve the remaining tooth structure as much as possible. Middle-aged and elderly patients are often aware of the need for orthodontic treatment, but they are hesitant to use the traditional orthodontic treatment method using brackets because of the social gaze. In this case, clear aligners can be a good option. So, in this article, a case in which aesthetic needs were resolved with clear aligners alone and another case in which satisfactory results were obtained through restorative treatment following clear aligners application are reported.

• The korean journal of orthodontics
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• v.54 no.5
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• pp.284-302
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• 2024

Objective: External apical root resorption (EARR) is characterized by permanent loss of dental structure at the root apex. This study aimed to systematically review gene polymorphisms associated with EARR in orthodontic patients. Methods: Electronic database searches were performed across several databases. Results: This systematic review included 21 studies. Outcome measures were based on tooth dimensions observed on radiographs obtained before and after treatment. Polymorphisms in the following genes were genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis: purinergic-receptor-P2X, ligand-gated ion channel 7 (P2RX7), caspase-1/interleukin-converting enzyme (CASP1/ICE), caspase-5 (CASP5), IL-1beta (IL1B), IL-1alpha (IL1A), interleukin-1 receptor antagonist gene (IL1RN), tissue non-specific alkaline phosphatase (TNSALP), tumor necrosis factor-alpha (TNFα), tumor necrosis factor receptor superfamily gene member 11a (TNFRSF11A), secreted phosphoprotein 1 (SPP1), tumor necrosis factor receptor superfamily gene member 11b (TNFRSF11B), interleukin 17A (IL17), interleukin 6 (IL6), receptor activator of nuclear factor-kappa B (RANK), osteoprotegerin (OPG), stromal antigen 2 (STAG2), vitamin D receptor (VDR), cytochrome P450 family 24 subfamily A member 1 (CYP24A1), cytochrome P450 family 27 subfamily B (CYP27B1), group-specific component (GC), and interleukin-1 receptor-associated kinases 1 (IRAK1). Conclusions: Almost all studies suggested that IL1 gene is associated with EARR. Additionally, P2RX7 may be an important factor contributing to the etiopathogenesis of EARR. TNFRSF11A, SPP1, IL1RN, IL6, TNFRSF11B, STAG2, VDR, IRAK1, IL-17, CASP1/ICE and CASP5 have been identified in isolated studies. Further observational studies are needed to better explain the association between these genes and EARR.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.8 no.1
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• pp.76-82
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• 1999

Zinc phosphate cement has long been the material of choice for permanent luting of cast restorations, and through many years of use has been considered effective to retain castings. However, cast restorations cemented with this material have been susceptible to secondary caries. Glass ionomer luting agents become available in the late 1970s. These material s, through release of fluoride, show considerable promise as a means of reducing secondary caries. Other favorable traits include significantly less disintegration in vivo than zinc phosphate cements, a film thickness comparable to that of zinc phosphate cement, and adhesion to tooth structure. Compomer materials were created in 1993 as a filling material for deciduous teeth, cervical lesions, and class III cavities. In the meantime, compomer have been developed as chemical hardening cements for cast gold restorations. The aim of this paper is to review the articles on luting cements to help the choice of dental cements.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.139-150
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• 1988

The purpose of this study was to evaluate the marginal adaptation of Class V resin restorations by the filling techniques. The cavities were filled with Heliosit$^{(R)}$ light curing composite resin system in accordance with the following three filling techniques - bulk-pack placement technique, apical to occlusal layering placement technique, and buccolingual layering placement technique. And the interface between the restoration and the tooth structure was observed with scanning electron microscope. The following results were obtained. 1. Marginal adaptation of enamel showed excellent irrespective of the filling techniques. 2. Marginal leakage of dentin was observed irrespective of the filling techniques. 3. No difference of marginal adaptation according to the filling techniques was observed in light curing composite resin.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.271-276
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• 2010

High-speed air turbine handpieces have been used as a denture cutting tool in clinical dentistry for over 50 years. The denture high-speed air turbine handpiece is currently used as the main means of cutting tooth structure and restorative materials in a wide range of denture manufacturing. But little study has been reported on their performance analysis. This research would show the performance characteristics of denture air turbine handpiece by using CFD.