• 치과방사선
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• 제20권1호
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• pp.103-112
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• 1990

The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-2l0 Head & Neck Section/sup R/, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70Kvp and 15mA, 1/4 second (8 inch cone) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

• 대한치과교정학회지
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• 제22권4호
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• pp.869-880
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• 1992

The purpose of this study was to evaluate the difference and relationship between the slope of articular eminence and the inclination of upper and lower incisor teeth, which are related to the functional stability of occlusion in mandibular protrusion, according to Ricketts' facial types, by the use of lateral cephalogram and SAM2 articulator in 68-adult normal occlusion without tooth missing, orthodontic treatment and occlusal equilibration. The results of this study were as follows : 1 . The angle of articular eminence slope to occlusal plane in brachyfacial type was steeper than that in dolichofacial type, but the angle of articular eminence slope to SN plane and FH plane was not different between facial types. 2. The upper incisor axis in dolichofacial type was steeper than that in brachyfacial type, but lingual surface slope of upper incisor was not different between facial types. 3. In all samples there was a positive correlation between the angle of articular eminence slope and the lingual surface slope of upper incisor to SN plane and FH plane, and in mesofacial type there was a positive correlation between the angle of articular eminence slope and the lingual surface slope of upper incisor to SN plane, FH plane and occlusal plane, and in brachyfacial type there was a positive correlation between the angle of articular eminence slope and the lingual surface slope of upper incisor to occlusal plane. 4. In all samples there was a positive correlation between the angle of articular eminence slope and the angle of Dc-Gn to SN plane, and in mesofacial type there was a positive correlation between the angle of articular eminence slope and the angle of Dc-Gn to occlusal plane, and in brachyfacial type there was a positive correlation between the angle of articular eminence slope and the angle of Dc-Gn to SN plane and FH plane. 5. In all samples there was a positive correlation between the angle of Dc-Gn and the lingual surface slope of upper incisor to SN plane and FH plane, and in mesofacial type there was a positive correlation between the angle of Dc-Gn and the lingual surface slope of upper incisor to SN plane. 6. In all samples and facial types there was a negative correlation between MP to 1 axis and condylar incisal angle.

• 대한치과보철학회지
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• 제36권1호
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• pp.81-103
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• 1998

The purpose of this study was to compare and evaluate the differences in masticatory performance, muscle activity, and patterns of occlusal contact between persons with natural dentition and removable partial denture wearers. Twenty healthy adult subjects with more than 28 teeth and thirteen removable partial denture wearers that classified Kennedy classification I was selected. The degree of pulverized rice and peanut was measured and analyzed by means of sieving method to compare the masticatory performance. For the muscle activity, EMG was recorded in selected muscles(Temporalis and masseter muscle) during mastication and resting state. The occlusal record in maximal intercuspation was taken with a silicone occlusal bite registration material for analysis of the patterns of occlusal contact. The obtained results were as follows: 1. When chewed peanuts, masticatory performance ratio at 10-sieve size was 81.31% in natural dentition group. In removable partial denture wearer, 27.01% without RPD and 69.09% with RPD. When chewed rice, 42.04%, 11.87%, and 21.58%, respectively. The differences of masticatory performance ratio between groups were statistically significant at the 0.05 level. 2. The mean EMG value in resting state was $1.06{\mu}V$ on temporal muscle, $0.98{\mu}V$ on masseter muscle in natural dentition group. In removable partial denture wearers, $1.13{\mu}V$ on temporal muscle, $1.05{\mu}V$ on masseter muscle without RPD and $1.11{\mu}V$ on temporal muscle, $1.04{\mu}V$ on masseter muscle with RPD. 3. The mean EMG value during mastication was $45.64{\mu}V$ in natural dentition group, and in removable partial denture wearers, $22.06{\mu}V$ without RPD and $31.01{\mu}V$ with RPD when chewed peanuts. When chewed rice, $45.24{\mu}V,\;25.53{\mu}V\;and\;32.14{\mu}V$, respectively. The differences of mean masticatory EMG value between groups were statistically significant at the 0.05 level. 4. The number of posterior occlusal contact point was 20.15 in natural dentition group and 11.92 in removable partial denture wearers. The area of perforated surface was $16.50mm^2$ in natural dentition group and $6.06mm^2$ in removable partial denture wearers. The area of contact surface was $78.93mm^2,\;51.52mm^2$, respectively. 5. The area of contact surface was effective to masticatory performance ratio in natural dentition group and removable partial denture wearers (p<0.05). From these results, it is concluded that in partially edentulous patient, masticatory efficiency can be improved by removable partial denture wearing, and for efficient mastication, tight occlusal contact surface shoud be maintained by maximum support that is provided from mucosa.

• Restorative Dentistry and Endodontics
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• 제30권5호
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• pp.355-362
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• 2005

본 연구는 복합레진을 광조사하기 전과 광조사한 후에 표면 전색제인 Biscover를 적용하여 이들에 대한 변연 미세누출을 평가하고, 또한 표면 전색제를 적용하지 않는 복합레진 수복물과의 미세누출 차이를 비교하기 위하여 시행하였다. 30개의 발거된 대구치의 협면 치경부에 5급 와동을 형성하여 다음과 같이 3개의 군으로 분류하였다; 대조군은 복합레진 표면에 Biscover를 적용하지 않은 군, 1군은 복합레진을 광조사하고 마무리한 후 Biscover를 적용한 군, 2군은 복합레진을 광조사하지 않고 Biscover를 적용한 군. 각 군의 시편은 실온의 증류수에 48시간 동안 보관한 후 $5^{\circ}C$와 $55^{\circ}C$에서 1,000회의 열 순환을 시행하고 2% methylene blue용액에 4시간 동안 침적시켰다. 20배율의 광학 입체현미경 하에서 각 군의 교합면측과 치은측 변연의 색소침투 정도를 관찰하여 미세누출 점수를 얻은후, 각군 간의 유의성을 검정하여 다음과 같은 결과를 얻었다. 1. 2군은 1군보다 교합면측과 치은측 변연 모두에서 높은 미세누출을 보였으나 통계학적으로 유의한 차이는 없었다 (p > 0.05). 2. 대조군은 교합면측 변연에서 1군과 2군보다 약간 높은 미세누출을 보였으며 , 치은측 변연에서 1군보다 약간 높게 그리고 2군과 비슷한 미세누출을 보였다 (p > 0.05). 3. 대조군과 2군은 교합면측 보다 치은측 변연에서 통계학적으로 높은 미세누출을 보였으며 (p < 0.05), 1군은 교합면측과 치은측의 변연 미세누출 간에 통계학적인 차이를 나타내지 않았다 (p > 0.05). 본 연구를 종합하면, Biscover는 중합된 복합레진 표면에 적용할 경우 치은측 변연의 미세누출을 감소시키는데 효과적이었다.

• 대한치과기공학회지
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• 제5권1호
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• pp.19-26
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• 1983

I got a conclusion as a result of that in case of constructing a full denture using acrylic resin teeth, porcelain teeth, and forming posterior occlusal surface of the artificial teeth by Type III Gold and Nickel crome alloy thus construdting a full denture and therefore comparing the above case with abrasion of Natural teeth. The result were as follows : 1. The abrasion of Natural teeth and the abrasion of full denture constructed by Type III gold has a close resemblance. 2. The one that has the hightest degree of abrasion is full denture that's using, with acrylic resin teeth, maxillary and mandibular And the lowest abrasion is natural teeth-natural teeth. 3. In case of single denture, that's opposing to natural teeth, the one that has the hightest degree of abrasion is a full denture that's using Acrylic resin teeth and the lowest abrasion is a full denture that's forming occlusal surface by Type III gold. 4. The single denture, which is opposing to type III gold teeth, was abraded above everything by full denture which is constructed by porcelain teeth. 5. In the same teeth, the abrasion of mandibular teeth was greater than that of mandibular teeth was greater than that of maxillary teeth. 6. The abrasion degree of Acrylic resin teeth has no direct mutual connection with material hardness which is opposing to.

• Journal of Oral Medicine and Pain
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• 제35권1호
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• pp.75-81
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• 2010

측두하악장애 치료를 위해 사용되는 야간 이갈이 교합장치의 착용 여건을 in vitro 실험으로 재현함으로써, 수분 침윤 및 건조 주기 반복 처리가 교합장치용 레진의 표면경도와 굴곡강도에 미치는 영향을 알아보고자 하였다. 폴리메틸메타크릴레이트를 주성분으로 하는 교합장치용 레진을 사용하여 막대형의 시편을 제작하였다. 대조군 1로 사용되는 레진 시편은 $37^{\circ}C$에서 7일간 수분에 침윤시킨 후, 그리고 대조군 2의 레진 시편은 상온에서 7일간 건조한 상태로 유지한 후 각각 시편의 표면경도와 굴곡강도를 측정하였다. 실험군으로 사용되는 레진 시편을 $37^{\circ}C$에서 7일간 수분에 침윤 시킨 후, 하루 8시간 동안 침수를 시키고 16시간 동안은 상온에서 건조를 시키는 수분 침윤 및 건조 주기 처리를 30일 동안 계속 하였다. 이러한 주기적 처리 1일째, 7일째, 30일째에 시편의 표면경도와 굴곡강도를 측정하였다. 대조군과 실험군의 표면경도와 굴곡강도의 차이에 대해 통계분석을 하여 다음과 같은 결과를 얻었다. 1. 실험군과 대조군의 교합장치용 레진의 표면경도는 수분 침윤 및 건조 주기의 반복 처리에도 유의한 차이를 보이지 않았다. 2. 교합장치용 레진의 굴곡강도는 수분 침윤 및 건조 주기를 30일간 처리한 실험군이 1일째의 실험군 및 제1대조군에 비해 더 컸다. 이러한 결과를 측두하악장애 환자들에서 교합장치를 사용하고 보관하는 방법에 고려할 수 있을 것으로 사료된다.

• Restorative Dentistry and Endodontics
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• 제14권2호
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• pp.1-4
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• 1989

To determine the thickness of coronal hard structure the minimal distance between pupal surface and outer surface of crown was measured by means of Bowley gauge on extracted first molars. Upper(28 teeth) and lower(24 teeth) were carefully collected from 30-39 years of age and male. The teeth were split mesio-distally through central pit. On the split surface various part which are deeply related in cavity preparation were measured (schematic drawing). The results were as follows: A : Distance from mesio-cervical enamel to pulp chamber surface. upper $2.63{\pm}0.19$(mm) Lower $2.18{\pm}0.27$(um) B : Distance from mesial chamber ceiling to mesial surface upper $2.75{\pm}0.34$ Lower $2.62{\pm}0.31$ C : Distance from mesial chamber ceiling to occlusal surface upper $3.82{\pm}0.51$ Lower $3.49{\pm}0.50$ D : Distance from distal chamber ceiling to occlusal surface upper $4.28{\pm}0.69$ Lower $3.90{\pm}0.52$ E : Distance from distal chamber ceiling to distal surface upper $2.79{\pm}0.45$ Lower $2.41{\pm}0.40$ F : Distance from disto cervical enamel to pulp chamber surface upper $2.49{\pm}0.24$ Lower $2.39{\pm}0.25$.

• The Journal of Advanced Prosthodontics
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• 제11권3호
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• pp.169-178
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• 2019

PURPOSE. While dental implants have displayed high success rates, poor mechanical fixation is a common complication, and their biomechanical response to occlusal loading remains poorly understood. This study aimed to develop and validate a computational model of a natural first premolar and a dental implant with matching crown morphology, and quantify their mechanical response to loading at the occlusal surface. MATERIALS AND METHODS. A finite-element model of the stomatognathic system comprising the mandible, first premolar and periodontal ligament (PDL) was developed based on a natural human tooth, and a model of a dental implant of identical occlusal geometry was also created. Occlusal loading was simulated using point forces applied at seven landmarks on each crown. Model predictions were validated using strain gauge measurements acquired during loading of matched physical models of the tooth and implant assemblies. RESULTS. For the natural tooth, the maximum vonMises stress (6.4 MPa) and maximal principal strains at the mandible ($1.8m{\varepsilon}$, $-1.7m{\varepsilon}$) were lower than those observed at the prosthetic tooth (12.5 MPa, $3.2m{\varepsilon}$, and $-4.4m{\varepsilon}$, respectively). As occlusal load was applied more bucally relative to the tooth central axis, stress and strain magnitudes increased. CONCLUSION. Occlusal loading of the natural tooth results in lower stress-strain magnitudes in the underlying alveolar bone than those associated with a dental implant of matched occlusal anatomy. The PDL may function to mitigate axial and bending stress intensities resulting from off-centered occlusal loads. The findings may be useful in dental implant design, restoration material selection, and surgical planning.

• Restorative Dentistry and Endodontics
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• 제42권4호
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• pp.253-263
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• 2017

Objectives: The aim of the study was to evaluate the 5-year clinical performance of occlusal carious restorations using nanofill and microhybrid composites, in combination with 3-step etch-and-rinse adhesives, in patients who were going to commence orthodontic treatment. Materials and Methods: A total of 118 restorations for occlusal caries were conducted prior to orthodontic treatment. Occlusal restorations were performed both with Filtek Supreme XT (3M ESPE) and Filtek Z250 (3M ESPE) before beginning orthodontic treatment with fixed orthodontic bands. Restorations were clinically evaluated at baseline and at 1, 2, 3, 4, and 5-year recalls. Results: None of the microhybrid (Filtek Z250) and nanofill (Filtek Supreme XT) composite restorations was clinically unacceptable with respect to color match, marginal discoloration, wear or loss of anatomical form, recurrent caries, marginal adaptation, or surface texture. A 100% success rate was recorded for both composite materials. There were no statistically significant differences in any of the clinical evaluation criteria between Filtek Z250 and Filtek Supreme XT restorations for each evaluation period. Conclusions: The composite restorations showed promising clinical results relating to color matching, marginal discoloration, wear or loss of anatomical form, recurrent caries, marginal adaptation, and surface texture at the end of the 5-year evaluation period.

• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.444-450
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• 2014

PURPOSE. To compare the accuracy of marginal and internal adaptation of zirconia (Zr) copings fabricated on anatomic (A), semi-anatomic (SA) and non-anatomic (NA) occlusal surface preparations. MATERIALS AND METHODS. 45 extracted bicuspid teeth were prepared for receiving zirconia crowns, with different occlusal preparation designs A=15, SA=15 & NA=15. The Zr copings were fabricated by using CAD4DENT, CAD/CAM. The copings were adjusted, cemented and were cross sectioned centrally from buccal cusp tip to lingual cusp tip into mesial and distal halves. The copings were examined under electron microscope at ${\times}200$ magnification and the measurements were recorded at 9 predetermined areas in micrometers. RESULTS. Overall mean gap values for the three groups was found to be $155.93{\pm}33.98{\mu}m$ with Anatomical Occlusal preparation design having the least gap value of $139.23{\pm}30.85{\mu}m$ showing the best adaptation among the groups. Post Hoc Tukey's test showed a statistically significant difference (P=.007) between the means of gap for A & NA preparation designs. Measurements recorded at 9 predetermined points showed variations for the three groups. CONCLUSION. Anatomical occlusal preparation designs resulted in better marginal and internal adaptation of Zr copings. There is a considerable variation between the measured marginal and internal gap values for the Zr copings fabricated by the (CAD4DENT-CAD/CAM). This variation may be associated with the lack of standardization of the preparation of teeth, computerized designing of the coping for each tooth, cement used, uniform pressure application during the cementation of the copings, sectioning of the copings and the microscopic measurements.