• 대한치과기공학회지
• /
• 제41권2호
• /
• pp.81-86
• /
• 2019

Purpose: The purpose of the present study was to compare the internal fit of two different temporary restorations fabricated by dental CAD/CAM system and to evaluate clinical effectiveness. Methods: Composite resin tooth of the maxillary first molar was prepared as occlusal reduction(2.0mm), axial reduction(1mm offset), vertical angle(6 degree) and chamfer margin for a temporary crown and duplicated epoxy die was fabricated. The epoxy dies were used to fabricate provisional restorations by CAD/CAM milling technique or 3D-printing technique. The inner data from all crowns were superimposed on the master die file in the 'best-fit alignment' method using 3D analysis software. Statistical analysis was performed using a Wilcoxon's rank sum test for differences between groups. Results: It showed that the internal RMS(Root Mean Square) values of the additive group were significantly larger than those of other group. No significant differences in internal discrepancies were observed in the temporary crowns among the 2 groups with different manufacturing method. Conclusion: All the groups had the internal fit within the clinical acceptable range (< $50{\mu}m$). The continuous research in the future to be applied clinically for the adaptation of additive manufacturing technique are needed.

• Journal of Yeungnam Medical Science
• /
• 제40권3호
• /
• pp.302-307
• /
• 2023

With recent developments in digital dentistry, research on techniques and materials for three-dimensional (3D) printing is actively underway. We report the clinical applications and outcomes of 3D printing of temporary crowns fabricated with polylactic acid (PLA) using a fused deposition modeling (FDM) printer. Five participants were recruited from among patients scheduled to be treated with a single full-coverage crown at a dental clinic in a university medical center from June to August 2022. We used 3D-printed crowns fabricated with PLA using an FDM printer as temporary crowns and were assessed for discomfort, fracture, and dislodging. The 3D-printed temporary crowns were maintained without fracture, dislodging, or discomfort until the permanent prosthesis was ready. The average time required for printing the temporary crowns was approximately 7 minutes. The 3D printing of temporary crowns with PLA using an FDM printer is a convenient process for dentists. However, these crowns have some limitations, such as rough surface texture and translucency; therefore, the 3D printing process should be improved to produce better prostheses.

• 대한소아치과학회지
• /
• 제24권2호
• /
• pp.475-483
• /
• 1997

Fracture of the crown in a permanent incisor is relatively common. When it occurs with pulp exposure, it presents both restorative and endodontic problems. In the restoration of a fractured incisor, reattachment of the original fragment or restoration with a composite resin is preferred over a temporary crown. If fractured fragment is intact, the tooth can be restored with reattachment of the fragment. An exposed pulp in a young crown-fractured incisor is usually treated with either pulp capping or pulpotomy depending on the size of an exposure and time elapsed since injury. However, in teeth showing vital and/or hyperplastic pulp tissue at the exposure, only superficial layers of the pulp and surrounding dentin should be removed : i.e. partial pulpotomy can be performed in immature as well as mature teeth. This paper reports 2 cases of crown-fractured permanent incisors with pulp exposure that had been treated by reattachment of original fragment followed by partial pulpotomy or partial pulpectomy. The following results are obtained. ; 1. Fragment reattachment is an acceptable semi-permanent restoration of crown fractured young permanent incisor. 2. Partial pulpotomy is recommended as the treatment of choice in crown-fractured permanent teeth with pulp exposure.

• 대한치과기공학회지
• /
• 제23권2호
• /
• pp.75-93
• /
• 2002

This research was preformed for the purpose of preparing the items of standard model of the national dental technician test base on the duty analysis of the dental technician. The results of the duty analysis for the dental technician follows. 1. The dental technician is a profession to make the oral function smooth through the dental supplement and equipment in a scientific method and the skilled technique. 2. The duty of the dental technician are determined as A. preparation for manufacture B. manufacture C. management of the place of the dental technology D. self-development. A. The field of "the preparation for manufacture" are determined as 1. to confirm work authorization 2. To confirm the working model, B. The field of "In manufacture" are determined as 1. to manufacture the temporary crown 2. to manufacture the inlay and crown & bridge prosthesis 3. to manufacture the porcelain fused metal crown prosthesis 4. to manufacture the all ceramic crown prosthesis 5. to manufacture the temporary denture prosthesis 6. to manufacture the partial denture prosthesis 7. to manufacture the complete denture prosthesis 8. to manufacture the attachment prosthesis 9. to manufacture implant prosthesis 10. to manufacture the removable orthodontic device, 11. to manufacture the fixed orthodontic device, 12. to manufacture the orthodontic study cast C. The field of "in management of the dental lab." are determined as 1. management 2. to control the dental lab. D. The field of "In the self-development" are determined as 1. to improve the professionalism 2. self-control. 3. The developing items selected under the duty evaluation of the dental technician are l7s in the manufacture preparation, 1,011s in the manufacture, 7s in the management for the dental technology, 5s in self-development, and in all together 1,040s

• The Journal of Advanced Prosthodontics
• /
• 제15권2호
• /
• pp.72-79
• /
• 2023

PURPOSE. The purpose of this in vitro study was to compare the accuracy of various 3D printers and a milling machine. MATERIALS AND METHODS. The die model was designed using CAD (Autodesk Inventor 2018 sp3). The 30 ㎛ cement space was given to the die and the ideal crown of the mandibular left first molar was designed using CAD (ExoCAD). The crowns were produced using the milling machine (Imes-icore 250i) and the 3D printers (Zenith U, Zenith D, W11) and they were divided into four groups. In all groups, the interior of each crown was scanned (Identica blue) and superimposed (Geomagic Control X) with the previously designed die. The difference between the die and the actual crown was measured at specific points. The Kruskal-Wallis test, the Mann-Whitney test, and Bonferroni's method were performed with a statistical analysis software (P < .008 in inter-group comparison P < .001 in intra-group comparison). RESULTS. In all groups, the center of the occlusal area and the anti-rotational dimple area showed significantly greater difference and the marginal area showed the smallest difference comparatively. The mean value of the difference in each area and the sum of the differences were higher in order of W11, Imes-icore 250i, Zenith D, and Zenith U. CONCLUSION. The digital light processing (DLP) method shows higher accuracy compared to the sereolithography (SLA) method using the same resin material.

• 구강회복응용과학지
• /
• 제36권4호
• /
• pp.254-261
• /
• 2020

목적: 본 연구의 목적은 서로 다른 제작 방법인 절삭 가공과 적층 가공 기술로 제작된 임시 보철물의 변연 및 내면 적합도를 평가하는 것이다. 연구 재료 및 방법: 상악 우측 제1대구치를 도재 수복을 위한 지대치 모형으로 준비하였다. 석고를 이용하여 총 40개의 실험 모형으로 복제하였고, 각각의 실험 모형을 구강 스캐너를 사용하여 스캔 데이터를 획득하였다. 3종의 3D 프린터(Meg-printer 2; Megagen, Zenith U; Dentis 그리고 Zenith D; Dentis) 및 1종의 밀링 장비(imes-icore 450i; imes-icore GmbH)를 사용하여 각 그룹당 10개의 임시 보철물을 제작하였다. 임시 보철물의 내면에 실리콘을 채우고 모형에 적합하여 중합이 완료된 후, 실리콘으로 내면이 복제되어 있는 실험 모형을 구강 스캐너를 사용하여 스캔 데이터를 획득하였다. 3차원 검사 소프트웨어(Geomagic control X; 3D Systems)를 이용하여 변연 간격, 절대 변연 간격, 섐퍼, 축벽, 교두, 교합 영역의 적합도를 분석하였다. 통계 분석은 제작 방법의 차이를 비교하기 위해서 Kruskal-Wallis test를 사용하여 검증하였으며, 사후 검정을 위해서 Mann-Whitney U-test and Bonferroni correction method을 사용하였다(α = 0.05). 결과: 3종의 3D 프린터와 1종의 밀링 장비에서 제작된 임시 보철물의 절대 변연 간격은 유의한 차이를 보이지 않았다(P = 0.812). 축벽, 교합 간격에서 밀링 장비와 3D 프린터 사이에 유의한 차이를 보였다(P < 0.001). 결론: 3종의 3D 프린터로 제작된 임시 보철물의 변연 적합도는 모두 임상적 허용 범위(< 120 ㎛)에 있었으므로, 적합도 측면에서 본다면 임시 보철물 제작을 위해서 충분히 사용될 수 있다.

• 대한치과보철학회지
• /
• 제46권3호
• /
• pp.280-289
• /
• 2008

STATEMENT OF THE PROBLEM: Recent data regarding the effects the cement type and abutment heights on the retentive force of a prosthetic crown are inconsistent and unable to suggest clinical guidelines. PURPOSE OF THE STUDY: This study evaluated the effects of different types of temporary cements and abutment heights on the retentive strength of cement-retained implant-supported prostheses. MATERIALS AND METHODS: Prefabricated implant abutments, 4 mm in diameter, $8^{\circ}$taper per side, and light chamfer margins, were used. The abutment heights of the implants were 4 mm, 5.5 mm and 7 mm. Seven specimens of a single crown similar to a first premolar were fabricated. Six commercially available temporary cements, TempBond, TempBond NE, Cavitec, Procem, Dycal, and IRM, were used in this study. Twenty-four hours after cementation, the retentive strengths were measured using a universal testing machine with a crosshead speed of 0.5 mm/min. The cementation procedures were repeated 3 times. The data was analyzed using two-way analysis of variance and a Tukey test (${\alpha}$=0.05). RESULTS: The tensile bond strength ranged from 1.76 kg to 19.98 kg. The lowest tensile strengths were similar in the TempBond and Cavitec agents. Dycal showed the highest tensile bond strength (P<0.01). More force was required to remove the crowns cemented to the long abutments (P<0.05). CONCLUSION: TempBond and Cavitec agents showed the lowest mean tensile bond strength. The Dycal agent showed more than double the tensile bond strength of the TempBond agent.

• 대한소아치과학회지
• /
• 제23권4호
• /
• pp.818-839
• /
• 1996

The strain gage, holographic and photoelastic analysis etc. have been used for stress analysis of prosthesis, orthodontic or orthopedic appliances and filling materials. But these methods has some limitation in analyzing the internal stress. The Finite Element Analysis has been proved to compensate this defect and widely used in this area. The purpose of this study was to compare the stress distributions of the various temporary filling methods being used in pulpotomy procedure. Three different models were designed according to temporary filling material and method: amalgam filling with ZOE base(Model I), amalgam filling with ZPC sub-base and ZOE(Model II), IRM filling only(Model III). The results of the experiment were as follows: 1. In model I under the load case 6 and 1, the significant stress was shown to be concentrated on the buccal portion of crown. 2. Model II showed the similar pattern of stress distribution to Model I. 3. In model III under load case 2, the stress was mainly distributed on the buccal cusp tip and buccal margin of filling material. In same model under the load case 3, the stress was distributed on the lingual cusp tip. 4. Based on the above data, IRM can be assumed to have advantage over the other tested materials in reducing the incidence of crown fracture by localized the stress within the filling materials.

• The Journal of Advanced Prosthodontics
• /
• 제7권1호
• /
• pp.27-31
• /
• 2015

PURPOSE. The purpose of this report was to evaluate the effect of the fabrication method and material type on the fracture strength of provisional crowns. MATERIALS AND METHODS. A master model with one crown (maxillary left second premolar) was manufactured from Cr-Co alloy. The master model was scanned, and the data set was transferred to a CAD/CAM unit (Yenamak D50, Yenadent Ltd, Istanbul, Turkey) for the Cercon Base group. For the other groups, temporary crowns were produced by direct fabrication methods (Imident, Temdent, Structur Premium, Takilon, Systemp c&b II, and Acrytemp). The specimens were subjected to water storage at $37^{\circ}C$ for 24 hours, and then they were thermocycled (TC, $5000{\times}$, $5-55^{\circ}C$) (n=10). The maximum force at fracture (Fmax) was measured in a universal test machine at 1 mm/min. Data was analyzed by non-parametric statistics (${\alpha}$=.05). RESULTS. Fmax values varied between 711.09-1392.1 N. In the PMMA groups, Takilon showed the lowest values (711.09 N), and Cercon Base showed the highest values (959.59 N). In the composite groups, Structur Premium showed the highest values (1392.1 N), and Acrytemp showed the lowest values (910.05 N). The composite groups showed significantly higher values than the PMMA groups (P=.01). CONCLUSION. Composite-based materials showed significantly higher fracture strengths than PMMA-based materials. The CADCAM technique offers more advantages than the direct technique.

• 대한치과보철학회지
• /
• 제61권1호
• /
• pp.26-32
• /
• 2023

활동이 많은 소아 청소년 시기에는 치아의 외상이 흔하게 발생한다. 그 중 탈구로 인해 유착이 일어날 경우 임상검사를 통한 진단이 중요하며 성인이 된 후 심미적인 보철 수복을 위해서는 진단에 따른 치료가 중요하다. 본 증례는 외상으로 인해 유착된 치아를 치관절제술과 임플란트 식립을 통한 상악 전치부 심미 보철 수복 증례이다. 치관절제술 후 치관을 이용하여 보철 수복을 위한 공간 유지를 시행하였다. 성인이 된 후 guide surgery를 이용하여 정교한 임플란트 식립과 심미적인 보철 수복을 가능하게 하였으며, 상악 전치부임을 고려하여 원발성 안정성(primary stability) 확인 후 즉시 부하(immediate loading)를 시행하였다. 연조직 지지를 위해 임시치아의 윤곽 변화를 주며 임시치아를 교체하였고 digital wax-up 하여 최종 보철물을 수복하였다.