• 구강회복응용과학지
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• 제18권4호
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• pp.313-320
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• 2002

The purpose of the present study was to evaluate the marginal discrepancy and topography of artificial crown on teeth extracted due to severe periodontal disease. Twenty specimens were invested into metamethylacrylate resin and cutted into vertical slices along with the long axis of tooth. The selected marginal discrepancy between the outer edge of the crown and the finishing line of abutment was examined by stereo- microscope(Olympus, PM-VSP-3, Japan) at magnification of up to 10, and the topography of finishing margin on crown was observed by stereomicroscopeat magnification of up to $70{\times}$. The results were as follows. (1) The mean marginal discrepancy between extracted tooth and artificial crown were $50.82{\mu}m$. (2) There was a considerable difference in the microstructure of finishing margins among specimens. Microscopic Structure on finishing margin showed indefinite line, poor fit (open, underextended and overextended), distorted margin, and surface roughness. This study suggested that there could be necessary to consider the response of periodontium to the emergence profile of natural tooth and precision of marginal geometry while establishing treatment planning for the reconsruction of the artificial crown.

• Restorative Dentistry and Endodontics
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• 제49권1호
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• pp.6.1-6.16
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• 2024

Objectives: This study aimed to investigate the elemental analysis and microhardness of a bioactive material (Activa) and marginal tooth structure after storage in different media. Materials and Methods: Fifteen teeth received cervical restorations with occlusal enamel and gingival dentin margins using the tested material bonded with a universal adhesive, 5 of them on the 4 axial surfaces and the other 10 on only the 2 proximal surfaces. The first 5 teeth were sectioned into 4 restorations each, then stored in 4 different media; deionized water, Dulbecco's phosphate buffered saline (DPBS), Tris buffer, and saliva. The storage period for deionized water was 24 hours while it was 3 months for the other media. Each part was analyzed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis for different substrates/distances and the wt% of calcium, phosphorus, silica, and fluoride were calculated. The other 10 teeth were sectioned across the restoration, stored in either Tris buffer or saliva for 24 hours or 3 months, and were evaluated for microhardness of different substrates/areas. Data were analyzed using analysis of variance and Tukey's post hoc test. Results: Enamel and dentin interfaces in the DPBS group exhibited a significant increase in calcium and phosphorus wt%. Both silica and fluoride significantly increased in tooth structure up to a distance of 75 ㎛ in the 3-month-media groups than the immediate group. Storage media did not affect the microhardness values. Conclusions: SEM-EDS analysis suggests an ion movement between Activa and tooth structure through a universal adhesive while stored in DPBS.

• Restorative Dentistry and Endodontics
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• 제13권1호
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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.

• 대한소아치과학회지
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• 제28권3호
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• pp.530-534
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• 2001

많은 치과 임상가들은 아말감을 치질에 접착시키기 위해서 여러 접착재료를 이용해왔다. 이 런 술식의 장점으로는 미세누출의 감소로 인한 술후과민증의 감소, 변연파절의 감소, 삭제 후 치질의 강화, 적은 유지형태에서의 수복물의 유지등이 제시되어 왔다. 실제로 임상적 상황에서 이러한 술식의 장점을 확인할 필요가 있다. 이런 접착제가 임상적 환경에서 어떠한 잇점을 보이지 않는다면 시간과 비용을 낭비하는 이런 술식을 정당화하지 못할 것이다. 본 연구에서는 73개의 치아를 대상으로 하여 I급 와동과 II급 와동에 접착형과 비접착형 아말감으로 수복하였다. 접착제로는 Fuji I Glass Ionomer luting cement를 이용하였다. 평균 2년 후에 변연적합성을 평가하였으나 접착형 아말감과 비접착형 아말감 사이에 유의한 차이는 없었다.

• ALGAE
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• 제23권3호
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• pp.187-199
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• 2008

A study on the fine structure of the marine diatom Thalassiosira has been carried out during the periods from January 2007 to March 2008 in Korean coastal waters. As the third series of the Thalassiosira species, a fine structure, description, distribution and taxonomic remarks of the six Thalassiosira species were observed by means of light microscope and scanning electron microscope. The critical features of Thalassiosira species were a shape of external tubes of marginal strutted processes and labiate process. Six species showed each different shape of external tubes, marginal strutted processes and labiate process. The shape of external tube was divided into five types: T shape of Thalassiosira curviseriata, small-rounded shape of T. lundiana, double-layer form and flame shape of T. nordenskioeldii, tulip shape of T. punctigera and tooth-shape of T. tenera. This external character may be able to key character for positive identification of the Thalassiosira species. Of these Thalassiosira lundiana, T. minuscula and T. tenera were new records for Korean coastal waters.

• Restorative Dentistry and Endodontics
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• 제26권4호
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• pp.316-325
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• 2001

The purpose of this study was to evaluate the effect of adhesive curing timing on the direction of polymerization shrinkage of light-curing composite resin. In this study, the curing times of adhesive and composite resin were measured by differential scanning calorimeter(DSC). 28 extracted human molars were embedded in clear resin and box-type cavities were prepared. Based on DSC data, the experimental teeth were divided into 4 groups. Group 1: no bond; Group 2: late curing; Group 3: Intermediate curing; Group 4: Early curing. After treating with adhesive, the buccal cavities were filled with Z-100 hybrid composite resin and the lingual ones were filled with AEliteflo flowable composite resin. The depressions at the surface were measured by surface profilometer, then the specimens were embedded in clear resin and sectioned. Impressions were obtained and used to get epoxy resin replicas. The epoxy replicas were gold-coated and observed under SEM. Average Maximum Gap(AMG), Gap Proportion(GP), Average Marginal Index(AMI) were used to compare the shrinkage gap of each group. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA, Student-Newman-Keuls method. The results of this study were as follows. 1. Average Maximum Gap, Gap Proportion, Average Marginal Index and depression at the surface or Z-100 hybride composite resin were smaller than those of AEliteflo flowable composite resin(P<0.05). 2. When the bonding between composite resin and tooth structure was strong, the shrinkage gap was small, and depression at the surface was deep(P<0.05). 3. In the well-bonded group, light-curing composite resin shrank toward bonded cavity wall, not toward light source. The result suggested that the direction of polymerization shrinkage was affected by the quality of bonding in the dentin-resin interface. The strong was the bonding between composite resin and tooth structure, the smaller was the gap and the deeper was the depression at the surface. Then the flow to compensate the polymerization shrinkage proceeded from surface to bonded cavity wall.

• 대한치과보철학회지
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• 제26권1호
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• pp.51-61
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• 1988

The recently introduced castable glass ceramics incorporate properties characteristic of natural teeth and they are regarded as an ideal material to restore lost tooth structure. The purpose of this study was to compare the marginal fit of castable ceramic crown with that of the metal-ceramic crown in the process of heat treatment. Two master dies for castable ceramic crowns and metal-ceramic crowns were fabricated from being cast with the base metal. Each master die was duplicated with addition silicone and hard stone. Ten castable ceramic crowns were made on each hard stone die and their marginal openings were measured three times first, after casting; second, after ceramming; third, after shading. The other ten metal-ceramic crowns were made on each hard stone die and their marginal openings were measured three times : first, after casting; second, after degassing; third, after porcelain veneering. Each crown was seated on its master die with the constant force delivered by loading jig. And then, marginal openings were measured on four locations by optical projector at X50 magnification. The results were as follows: 1. The mean marginal openings of castable ceramic crowns were $31.1{\pm}12.7{\mu}m$ after casting; $44.6{\pm}12.8{\mu}m$ after ceramming; $51.2{\pm}16.8{\mu}m$ after shading. 2. The mean marginal openings of the metal-ceramic crowns were $26.2{\pm}13.8{\mu}m$ after casting; $29.8{\pm}10.3{\mu}m$ after degassing; $38.0{\pm}14.5{\mu}m$ after porcelain veneering. 3. There was significant increase in the marginal opening of castable ceramic crowns after ceramming, while metal-ceramic crowns sho(wed significant increase after porcelain veneering (p<0.05). 4. Marginal fit of metal-ceramic crown was better than that of castable ceramic crown (p<0.01).

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.291-316
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• 1993

Restorative procedures can lead to tooth fracture due to the relatively small amount of the remaining tooth structure. It is essential to prevent fractures by having a clear concept of the designs for cavity preparations. Among the several parameters in cavity designs, profound understanding of isthmus width factor would facilitate selection of the appropriate cavity preparation for a specific clinical situation. In this study, MO amalgam cavity were prepared on maxillary first premolar and filled with amalgam. Three dimensional, model with 1365 8-node brick elements was made by serial photographic method. In this model, isthmus was varied in width at 1/4, 1/3, 1/2 and 2/3 of intercuspal width and material properties were given for three element groups, i.e., enamel, dentin and amalgam. A load of 500 N was applied vertically on amalgam and enamel. In case of enamel loading, 2 model (with and without amalgam) was compared to consider the possibility of play at the interface between tooth material and amalgam. These models were analyzed with three dimensional finite element method. The results were as follows: 1. The stress was concentrated on the facio-pulpal line angle and distal marginal ridge of the cavity. 2. With the increase of the isthmus width, the stress spread around the facio-pulpal line angle and the area of stress concentration moved toward the proximal box. 3. In case of narrow isthmus width, the initiation point of crack would be in the area of isthmus corner of the cavity, and with the increase of the isthmus width, it would move toward the proximal box and at the same time the possibility of crack increase at the distal marginal ridge. 4. The direction of crack progressed outward and downward from the facio-pulpal line angle, and with the increase of the isthmus width, it approximated vertical direction. At the marginal ridge, it occurred in vertical direction. 5. It would be favorable to make the isthmus width narrower than a third of the intercuspal width, and to cover the cusp if isthmus width were wider than half of the intercuspal width. 6. It is necessary to apply the possibility of play to the finite element analysis.

• 한국패류학회지
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• 제31권1호
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• pp.49-59
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• 2015

우리나라를 비롯한 아시아, 유럽, 호주 등에서 채집한 쇠우렁이 과 패류 8종 (Bithynia striatula, B. tentaculata, B. siamensis, B. leachi, B. kiusiuensis, B. misella, Bithynia sp., Gabbia australis) 을 대상으로 주사전자현미경 (SEM) 을 이용하여 치설을 관찰한 바 다음과 같은 결과를 얻었다. 치설열의 수는 B. siamensis와 B. leachi의 경우 60-70개로 다른 종들의 치설열의 수 40-50개보다 많았다. 관찰한 8종의 패류의 치설 구조는 좌우대칭으로 한 치설열에 7개의 치아가 있었다. 즉 1개의 중치를 중심으로 좌우에 각각 1개의 측치와 2개의 외연치가 분포하였다. 따라서 기본 치설식은 2:1:1:1:2로 표시할 수 있었다. 소첨두의 수와 모양은 개체별, 종별로 차이가 있었으며 중치에만 기저돌기가 분포하였다. 중치의 중앙돌기의 구조는 B. striatula, B. tentaculata, B. siamensis 및 Bithynia sp.의 구조가 다른 종들과 차이가 있었다.

• 대한치과기공학회지
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• 제41권1호
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• pp.21-27
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• 2019

Purpose: To evaluate 2D and 3D of occulsal, mesial-occlusal and mesial-occlusal-distal cavity of composite resin inlay. Methods: Abutment tooth 16, 36 of FDI system was selected for the study. Inlay prostheses classified as occlusal cavity (OC group), mesial-occlusal (MOC) and mesial-occlusal-distal cavity (MODC) were prepared using composite resin. Composite resin was injected with composite resin in prepared tooth cavity and then photopolymerized with UV light. Additional thermal polymerization was performed. Marginal gap of composite resin inlays were measured by digital microscope(x160) with silicone replica technique. The data was analyzed from statistical software for Kruskal-Wallis test (${\alpha}=0.05$). 3-dimensional analysis was analyzed through superimposition method. Results: The smallest 2D marginal fit measure of the three groups was $47.0{\pm}21.6{\mu}m$ in the MOC group. The largest 2D marginal was $69.1{\pm}33.8{\mu}m$ in the MODC group. In the trueness of the three groups, the most accurate figure was $14.4{\pm}2.3{\mu}m$ for the MODC group. In Precision, the most accurate figure was $14.5{\pm}4.3{\mu}m$ for the MODC group. Conclusion : In this study, 2D marginal fit of OC, MOC, and MODC cavities fabricated with composite resin was applicable to all clinical applications. In the 3D inner surface accuracy evaluation, the MODC group showed the accuracy results.