• Restorative Dentistry and Endodontics
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• 제46권2호
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• pp.18.1-18.13
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• 2021

Composite resins are the most commonly used dental restorative materials after minimally invasive dental procedures, and they offer an aesthetically pleasing appearance. An ideal composite restorative material should have wear properties similar to those of tooth tissues. Wear refers to the damaging, gradual loss or deformation of a material at solid surfaces. Depending on the mechanism of action, wear can be categorized as abrasive, adhesive, fatigue, or corrosive. Currently used composite resins cover a wide range of materials with diverse properties, offering dental clinicians multiple choices for anterior and posterior teeth. In order to improve the mechanical properties and the resistance to wear of composite materials, many types of monomers, silane coupling agents, and reinforcing fillers have been developed. Since resistance to wear is an important factor in determining the clinical success of composite resins, the purpose of this literature review was to define what constitutes wear. The discussion focuses on factors that contribute to the extent of wear as well as to the prevention of wear. Finally, the behavior of various types of existing composite materials such as nanohybrid, flowable, and computer-assisted design/computer-assisted manufacturing materials, was investigated, along with the factors that may cause or contribute to their wear.

• Imaging Science in Dentistry
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• 제30권3호
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• pp.183-188
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• 2000

Purpose: This study was to evaluate the beam quality of intraoral X-ray equipments used at Yonsei University Dental Hospital (YUDH) using the half value layer (HVL) and the characteristic curve of intraoral standard X-ray film. Materials and Methods : The study was done using the intraoral X -ray equipments used at each clinical department at YUDH. Aluminum filter was used to determine the HVL. Intraoral standard film was used to get the characteristic curve of each intraoral X-ray equipment. Results: Most of the HVLs of intraoral X-ray equipments were higher than the least recommended thickness, but the REX 601 model used at the operative dentistry department and the X-707 model used at the pediatric dentistry department had HVLs lower than the recommended thickness. The slopes of the characteristic curves of films taken using the PANP AS 601 model and REX 601 model at operative dentistry department, the X-70S model of prosthodontic dentistry department, and the REX 601 model at the student clinic were relatively low. Conclusion: HVL and the characteristic curve of X-ray film can be used to evaluate the beam quality of intraoral X-ray equipment. In order to get the best X-ray films with the least radiation exposure to patients and best diagnostic information in clinical dentistry, X -ray equipment should be managed in the planned and organized fashion.

• 치과방사선
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• 제12권1호
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• pp.35-42
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• 1982

Post-operative maxillary cyst may arise after the surgical intervention for maxillary sinusitis with the symptoms of swelling, pain and pus discharge in the buccal region. The author analized 66 cases clinically and radiographically which were diagnosed as post- operative maxillary cyst in SNUH during 5 years (1977. 8-1982. 7). The obtained results were as follows; 1. This cyst occurred more frequently in male than in female and the incidence is the highest in the 4th decade. 2. The right side was more frequently affected than the left side. 3. Initial radical operations of the maxillary sinueses were performed mainly between the age of 15 and 24 years. 4. The duration between the initial operation and the onset of cyst was mainly from 10 to 24 years. 5. Pain, swelling and pus discharge in the buccal region were most frequent chief complaints. 6. In panoramic radiographs, most of the post-operative maxillary cysts were monolocular type, showing distinct border, with smooth margin and without any definite sclerotic border. 7. In Waters' view, 43 cases showed radiographic changes due to cyst.

• 대한치과교정학회지
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• 제22권1호
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• pp.67-88
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• 1992

The purpose of this study was to investigate the changes of mandibular movement and muscle activity following orthognathic surgery in patients with mandibular prognathism. Lateral cephalogram, M.K.G., E.M.G. recordings were obtained immediately before surgery, and 2 months and 8 months after surgery. Among the patients who received orthognathic surgery, 19(13 men, 6 women) were selected for this study. Statistical analysis for each time interval differences were performed with the SPSS package. The results were as follows: 1. Compared with the pre-operative group (opening 349.7mm/sec, closing 313.1mm/sec), the mean values of the maximum opening and closing velocity in the skeletal Class III surgery group were significantly decreased in the 2 months post-operative (opening 232.9mm/sec, closing 206.9mm/sec), but the values tended to increase in the 8 months post-operative group (opening 280.9 mm/sec, closing 319.1mm/sec). 2. Compared with the pre-operative group (61.7 mm/sec), the maximum velocity of the terminal tooth contact increased in the 2 months (72mm/sec) and 8 months (105.7mm/sec) postoperative groups. 3. In the mean value of vertical freeway space, there was significant difference between the normal group and the pre-operative group, but not between the normal group and the 8 months post-operative group. 4. In the mean values of the maximum opening, the maximum anterio-posterior movement from centric-occlusion, and the lateral deviation from centric occlusion, there was no significant difference between the normal group and the surgery group (the pre-operative and the 8 months post-operative groups). 5. The mature swallowing pattern was 58% in the pre-operative group, but 90% in the 2 months post-operative group, and 63% in the 8 months post-operative group. 6. In the comparison of muscle activity, there was no significant difference between the normal group and the surgery group during the rest position. However, during cotton roll clenching, there was significant difference between the normal group and the pre-operative group, but not between the normal group and the 8 months post-operative group.

• 대한치과의사협회지
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• 제15권12호
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• pp.963-968
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• 1977

1. The purpose of this study is to determine the antibacterial effect of the remedies commonly used in operative dentistry. 2. Experiment were performed against staphylococcus albus which were isolated from different root canals. 3. Isolated bacteria were inoculated on nutrient agar and disk which has been saturated antiseptics were placed on it, then this plate was incubated for 48 hours at 37℃. 4. Inhibition zone were measured around antiseptic disks. 5. The results of 45 cases of experiments showed as follows. Average diameter of inhibition zone around phenol disk was 2.99 mm, camphorated phenol, 0.74 mm, formocresol, 13.46mm, formocresol (Korea), 12.7 mm, eugenol, 4.74mm, thymol, 16.46 mm.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제35권4호
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• pp.248-255
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• 2013

Reconstruction techniques of orofacial defects caused by wide excision of the intraoral malignant lesions are various. Although radial forearm free flap is a common donor site on reconstruction of soft tissue defect, anterolateral thigh (ALT) free flap also has an established site in orofacial soft tissue reconstruction as the favored donor flap with recent progress of the microsurgical technique. A 59-year-old female complained of hyperplastic mass on the right retromolar and buccal cheek, which was diagnosed as a squamous cell carcinoma (SCC) by an incisional biopsy. Before the operation, we planned a wide excision of the SCC lesion, supraomohyoid neck dissection, reconstruction with radial forearm free flap (RFFF), and split thickness skin graft. We accidentally found an arterial variation of the forearm area during elevation of RFFF, and changed the plan of reconstruction operation to reconstruction with ALT free flap. Operative sites was healed well during the post-operative period, and we referred to the department of radiation oncology for post-operative radiotherapy.

• Restorative Dentistry and Endodontics
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• 제8권1호
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• pp.31-44
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• 1982

Streptococcus mutans strains were isolated from dental plaques of carious lesions of 53 patients on mitis-salivarius-bacitracin (MSB) and mitis-salivarius(MS) medium as a supplement. The epidemiological investigation was carried out to determine the biotypes and serotypes of S. mutans isolates. For the serotyping, autoclaved extract antigens from the isolates and serotype-specific antisera against seven known serotypes of S. mutans were prepared. The serotypes of the isolates were demonstrated in immunodiffusion test. In addtition, the prevalence of ${\beta}$-hemolysis on 5% sheep blood agar plate in restricted anaerobic condition and yellow pigment production on 5% sucrose agar plate in less anaerobic condition among the isolates were investigated. The results were as follows: 1. Forty-eight S. mutans strains were isolated from dental plaque samples of 33 patients (62.3%) among 53 patients. 2. Of the isolates, some strains were not grown on MSB medium. 3. Serotype c S. mutans was found in 60.6%, serotype d was found in 30.3% of the patients who were known to harbor S. mutans. 4. Of. the isolates, serotype c isolates were most prevalent (43.8%), serotype d isolates were 25.0%, and serotype b, e, f and g isolates were also found but in lower frequencies. Serotype a S. mutans were not detected. 5. The correlation between serotype and biotype of the isolates was found in 78.6% of the typing cases. 6. Strains revealed ${\beta}$-hemolysis were in 52.1% of the isolates, strains produced yellow pigment were in 47.9% of the isolates, and with one exception, all the strains were belong to serotype c, e and f. 7. The majority of the isolates which revealed ${\beta}$-hemolysis appeared to be yellow pigmented, these isolates were belong to serotype c, e and f.

• Restorative Dentistry and Endodontics
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• 제5권1호
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• pp.41-46
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• 1979

Silver amalgam has superior mechanical and physical properties, therefore it has been widely used in dental clinics. But we have found the silver amalgam failures frequently, its important reasons are fracture, fallen-out, tarnish, corosion and secondary caries etc. The author studied the compressive strength of silver amalgam. The author made the standardized specimen, prepared the Black's Class II cavity on chromecobalt alloy, and placed the three types of Unitek$^{(R)}$ pin (Type of pins are straight type, "ㄱ" bent type, "$\sqcap$" bent type pin. The compressive strength was measured by (Dynamic Strain Meter Shinko Co. Japan). The author took the following results by comparing with the control group, not used pin. 1) Compressive force of silver amalgam in straight type pin was $187.11{\pm}39.00kg$, $252.98{\pm}31.91kg$ in "ㄱ" type bent pin, $189.00{\pm}37.46Kg$ in "$\sqcap$" type bent pin, $172.33{\pm}28.07Kg$ in the control group. 2) The statistic significance of the compressive strnegth between each group showed that "ㄱ" type, bent pin is stronger than the control group or straight type pin. 3) There were no difference of significances between the control group and straight type pin, control group and "ㄱ" type bent pin and "$\sqap$" type bent pin, "ㄱ" type' bent pin "$\sqcap$" and type bent pin.

• 대한심미치과학회지
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• 제9권1호
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• pp.38-41
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• 2000

매일의 임상에서 흔히 접하게 되면서도 항상 갈등을 야기하는 증례들이 있다. 그러나 많은 경우에 있어서 그 어려움 들은 우리가 치과 학문의 여러 분야들을 종합적으로 활용하지 못하고 단편적으로 접근을 하기 때문에 반복적으로 경험하는 것일 수도 있다. 현대의 치의학은 어느 특정한 한 분야를 선도적으로 주도해나가는 치과의사뿐 아니라, Super GP 로서 치의학의 모든 분야를 종합적으로 활용해 나갈 줄 이는 치과의사를 요구한다. Super GP를 추구하는 많은 치과의사들이 치주, 보존, 보철 등의 여러 전문적인 분야의 Interdisciplinary Approach를 통해 훌륭한 결과를 얻어내고 있지만 교정은 그중에서도 심미치료를 지향하는 치과의사들에게는 결코 빼놓을 수 없는 분야 중 하나일 것이다. 다음의 증례들은 치주, 보존, 보철 등의 분야와 함께 교정의 도움이 없이는 결코 얻을 수 없는 심미적인 결과였기에 함께 나누고자 한다.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.135-147
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• 1994

This study was conducted to evaluate whether the fatigue toughness of visible light cured composite resins could be improved and how much percentage of polymerzation shrinkage could be affected by additional heat treatment. 7 materials were investigated for this study: P-50, Lite-fil CR inlay, Pekafil, Clearfil CR inlay, Clearfil photo posterior, Z -100 and Progress. Diametral tensile strengths and linear shrinkages of composite resins were taken under visible light cured and additional post-cure heated condition and compared each other. A fatigue toughness of above materials was evaluated by measuring diametral tensile strength after they were repeatedly loaded with 120kgf/$cm^2$ up to 3000 cycles. The results obtained were as follows : 1. When composite resins were cured just by visible light, Lite fil CR inlay, Z -100 and Progress showed respectively higher diametral tensile strength than the other materials. Clearfil CR inlay, Clearfil photo posterior and Progress exhibited strong fatigue toughness compared to P-50 and Pekafil. 2. Post-cure heat treated composite resins had higher diametral tensile strengths than visible light cured composite resins at fatigue toughness test as well as no fatigue toughness test. 3. When Composite resins were additionally polymerized by post-cure heat treatment, P-50 showed weak fatigue toughness, on the contrary, Clearfil CR inlay, Z-100, Progress showed strong one. 4. When composite resins were cured just by visible light, percentage of polymerization linear shrinkage was the lowerest in Clearfil CR inlay, followed by, in ascending order, Clearfil photo posterior, Lite-fil CR inlay, Progress, Pekafil, P-50, and Z-100. In the case of post- cure heat treated composite resins, percentage of linear shrinkage was the lowest in Clearfil photo posterior, followed by, in ascending order, Lite-til CR inlay, Clearfil CR inlay, Progress, P-50, Pekafil and Z-100. 5. Percentage of polymerization linear shrinkage was greater in the post-cure heat treated composite resins than in the visible light cured composite resins and linear shrinkage increased significantly in Pekafil, Clearfil CR inlay, and Clearfil photo posterior between at the visible light cured and at the post-cure heat treated condition. The above results is saying that additional post-cure heat treatment on the composite resins for posterior restoration is able to affect on improvement of strength and fatigue toughness and lead to increase polymerization of composite resins.