• The Journal of Advanced Prosthodontics
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• 제11권3호
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• pp.187-192
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• 2019

PURPOSE. The purpose of this in vitro study was to investigate the fracture loads and modes of failure for the full range of natural teeth under simulated occlusal loading. MATERIALS AND METHODS. One hundred and forty natural teeth were taken from mandibles and maxillas of patients. There were 14 groups of teeth with 10 teeth in each group (5 males and 5 females). Each specimen was embedded in resin and mounted on a positioning jig, with the long axis of the tooth at an inclined angle of 30 degrees. A universal testing machine was used to measure the compression load at which fracture of the tooth specimen occurred; loads were applied on the incisal edge and/or functional cusp. RESULTS. The mean fracture load for the mandibular first premolar was the highest (2002 N) of all the types of teeth, while the mean fracture load for the maxillary first premolar was the lowest (525 N). Mean fracture loads for the mandibular and maxillary incisors, and the first and second maxillary premolars, had significantly lower values compared to the other types of teeth. The mean fracture load for the teeth from males was significantly greater than that for the teeth from females. There was an inverse relationship between age and mean fracture load, in which older teeth had lower fracture loads compared to younger teeth. CONCLUSION. The mean fracture loads for natural teeth were significantly different, with dependence on tooth position and the sex and age of the individual.

• Restorative Dentistry and Endodontics
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• 제13권2호
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• pp.337-348
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• 1988

The purpose of this study was to examine the fracture strength and characteristics of teeth with MOD cavity preparation. Freshly extracted sound maxillary premolars were cleaned and stored in normal saline solution $37^{\circ}C$ for 72 hours before experiments. The roots of teeth were embedded in a self-curing resin, and the exposed crown were maintained in a vertical position by a modelling wax in a brass ring. The MOD cavities were prepared with No. 57 carbide bur under high speed to a depth of 2.0mm and a width of 2.0mm(Fig.1). All the prepared teeth specimens were divided into 7 groups according to the mode of cavity form and restorative materials (Table 1, 2): Group I, unpreapred, intact teeth as control Group II, prepared cavity without restoration Group III, prepared teeth restored with amalgam Group IV, prepared teeth restored with composite resin (P-10) Group V, prepared teeth with beveled enamel margins restored with composite resin (P-10) Group VI, prepared teeth restored with light-cured composite resin (P-30) Group VII, prepard teeth with beveled enamel margins restored with light-cured composite resin (P-30) After placement of restorations, all of the specimens were stored in water at $37^{\circ}C$ for 72 hours before testing. All of the specimens were tested on the Instron Universal Testing machine (No. 6025) in order to evaluate the strength of fracture. One metal ball 5.0mm in diameter contacting the specimens parallel to the occlusal surface was used to in this study (Fig. 1). The fracture characteristics of the specimens were examined with naked eye and in the scanning electron microscope (JSM-20). The results obtained from this study were as follows: 1. The mean fracture strength was the highest in group VI and that in group II was the lowest. 2. The progress of crack of teeth propagated into the pulp cavity. 3. In case of the group of the restored teeth, the crack occurred to be accompanied with cuspal fracture. 4. The crack of restored teeth was initiated along the pulpo-axial line angle of the cavity.

• 대한치과보철학회지
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• 제42권3호
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• pp.280-293
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• 2004

Statement of problem. Glass fiber post is one of recent developments to accommodate esthetic restoration for endodontically treated teeth. This has many advantages over conventional post system in physical properties, esthetic factor, risk of root and restoration fracture, adhesion to core, radiopacity, removal and retrievabilty, biocompatibility and chemical stability. Purpose. This in vitro study was to evaluate the most suitable type of resin core for the glass fiber post through surveying the fracture modes and the maximum load that fractures the tooth. Material and methods. 50 sound maxillary premolars restored with glass fiber posts($ParaPost^{(R)}$ Fiber White) and different types of resin cores(ParaCore, $Z100^{TM}$, $Rebilda^{(R)}$ and $Admira^{(R)}$) were prepared and loaded to faiure in a universal test machine. The maximum fracture load and fracture mode were investigated in the specimens that were restored with resin and those of metal cast and core. With the data, Wilcoxon rank sum test was used to validate the significance between the test groups, and Tukey' s studentized range test was used to check if there is any significant statistical difference between each test group. Every analysis was approved with 95% reliance. Results. On measuring the maximum fracture load of teeth specimens, there was a significant difference between the maximum fracture loads of the tooth specimens. ParaCore showed the highest mean maximum fracture load followed by $Z100^{TM}$. And, the distribution of fracture mode of tooth specimens showed generally Type D, the three parted fracture of the core around the post was mostly seen(62.5%), and specifically, ParaCore showed 90% and $Z100^{TM}$ showed 100% Type D fracture. Conclusion. Referring to the values of maximum fracture load and mean compressive fracture load, ParaCore and $Z100^{TM}$ had high values and are recommended as tooth colored resin core material for glass fiber post. CLINICAL IMPLICATIONS. This study was carried out intending to be of aid in selecting the appropriate resin core for the glass fiber post. The dual cure type composite resin ParaCore and light cure type composite resin $Z100^{TM}$ have good properties and are recommended as tooth colored resin core material for glass fiber post.

• 한국기계가공학회지
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• 제7권3호
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• pp.110-114
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• 2008

In this study, to examine the friction coefficient and wear amount of dental prosthesis, pin-on-disk type wear test were at room temperature. Vickers hardness and fracture toughness measurement of dental materials were preformed. Microscopic observations on worn surfaces of specimens were conducted by SEM. The friction coefficient of dental material was investigated according to weight and slinging velocity. dental material have investigated composed to nature teeth.

• Tribology and Lubricants
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• 제24권1호
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• pp.44-48
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• 2008

The wear characteristics of the gold alloy dental prosthesis have been investigated. The wear tests were performed by using a pin-on-disk wear tester at room temperature. Vickers hardness and fracture toughness measurement of dental materials were preformed. Microscopic observations on worn surfaces of specimens were conducted by microscope. The friction coefficient of the gold alloy dental prosthesis was investigated according to weight and slinging velocity. The hardness of the gold alloy dental prosthesis were similar and a half of the enamel of natural teeth.

• 대한수의학회지
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• 제50권4호
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• pp.303-310
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• 2010

Demand on specialized feline dentistry has increased over the years, partly due to growing feline population in Korea. Despite the notable increase in the population, not much researches has been conducted on oral disease for stray cats. Thus this research was conducted on 81 adult stray cats from Gwangju in Korea (42 males and 39 females) with average weight of 3.4 kg and also focused on occurrence of periodontal disease (plaque and calculus), feline odontoclastic resorptive lesion (FORL), stomatitis and tooth anomaly. Formation of dental plaque and calculus were abundant on maxilla than mandible, especially distributed much on 4th premolar teeth and 1st molar teeth. After thorough examination of oral cavity, 33 stray cats (40.7%) were found to have oral disease. Eighteen stray cats (22.2%) had tooth fracture which was evident on cuspid and missing teeth were present on 2nd premolar tooth of maxilla and 2nd incisor of mandible amongst 20 stray cats (24.7%). FORL was present on cuspids and 2nd premolar tooth of maxilla among 10 stray cats (12.3%). Stomatitis was involved with FORL, missing tooth, and tooth fracture. Therefore, it was determined that stomatitis, FORL, and periodontal disease were closely associated.

• Tribology and Lubricants
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• 제23권6호
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• pp.318-322
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• 2007

The wear characteristics in supre-A dental material have been investigated. The wear tests were performed by using pin-on-disk wear tester at room temperature. Vickers hardness and fracture toughness measurement of dental materials were preformed. Microscopic observations on worn surfaces of specimens were conducted by SEM. The friction coefficient of supper-A material was investigated according to weight and slinging velocity. The hardness of supper-A material was a half of the enamel of natural teeth.

• 대한치과의사협회지
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• 제57권7호
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• pp.403-411
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• 2019

A cracked tooth is defined as an incomplete fracture initiated from the crown and extending subgingivally and usually directed mesiodistally. Cracked teeth were most frequently involved in mandibular and maxillary molars at the age of 50s. Cracks occurred mainly in nonbonded restorations such as gold and amalgam, and majority of cracks were found in intact teeth. A pulpal and periapical diagnosis is dependent on the extent of the crack and duration of the symptom. The pulp of a cracked tooth might become inflamed because of microleakage, which induces thermal sensitivity. Once the crack has extended and exposed the pulp, severe pulp and periapical pathosis will likely be present. In addition, the extended crack can cause a bony dehiscence with a resulting narrow and deep periodontal pocket. Therefore, early diagnosis of the cracked tooth and proper treatment planning are important for clinician.

• 대한심미치과학회지
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• 제32권1호
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• pp.4-7
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• 2023

1990년대 말부터 치과보철 수복에 응용된 초창기 지르코니아는 코핑 형태로 사용되었다. 이렇게 만들어진 보철 수복물은 기존의 다른 심미 금속 수복물의 구조물이나 프레임 역할을 하는 금속이 없어서 자연스러움이 필요한 전치부에 성공적으로 사용되었으나 구치부에서는 기능중에 상부 비니어링 포세린의 파절로 그 사용에 한계가 있었다. 그후 여기에 대한 해결 방안으로 강한 코핑 재료를 전체 보철물의 형태로 제작하는 단일구조 지르코니아 수복물이 제안되었다. 이것은 강한 힘에 대한 저항은 뛰어나지만 매우 희고 불투명한 지르코니아의 특성상 조금은 비심미적인 결과를 나타내었다. 그러나, 현재는 지르코니아의 투명도를 높이는 기술적인 진보로 구치부뿐만 아니라 전치부에서 강하면서도 심미적인 지르코니아 수복물 제작이 가능하게 되었다. 이 논문에서는 지금까지 개발된 여러 종류의 지르코니아 재료의 구조적 특징을 알고 실제로 사용하고 있는 지르코니아 제품이 어디에 속하는지 설명한다.

• 한국치위생학회지
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• 제13권5호
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• pp.819-826
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• 2013

Objectives : The purpose of this study was to analyze the types of dental emergencies. This study was carried out for dental trauma patients visiting the emergency room in H hospital from 2005 to 2006. Methods : Subjects were 252 patients. Demographic characteristics consisted of age, gender, dentition, and dental related injury. Results : Male patients had 1.65 times higher tooth injury than female. Teenagers had higher prevalence of tooth injury. Main cause of dental injury was falling down. Young children accounted for 41.7% of the injuries. Late evening was the highest outbreak time of injury. The most commonly affected teeth were central incisor and lateral incisor. The damage of oral soft tissue was more common than the that of alveolar bone. Main area of primary tooth loss was gingiva(10.7%), tongue or soft palate(7.5%), and frenulum(6.0%). Subluxation(28.6%) and luxation(28.6%) were main cause for the primary teeth. Tooth fracture(50.0%) were the most common injury. Conclusions : Thus, to understand the incidence, causes and patterns of dental trauma is to help preserving natural teeth. The results of this study could provide the clinical guidelines on the treatment of dental emergency patients.