• Title/Summary/Keyword: Cam Design

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THE EFFECT OF NITI ROTARY INSTRUMENTATION ON THE CONFIGURATION OF APICAL ROOT CANAL (NiTi Rotary Instruments에 의한 근관형성이 치근단부 근관형태에 미치는 영향)

  • Oh, Hyun-Jung;Hong, Chan-Ui;Cho, Yong-Bum
    • Restorative Dentistry and Endodontics
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    • v.22 no.1
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    • pp.244-253
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    • 1997
  • During preparation of narrow curved canals, procedural accidents such as, ledge, zipping, and transportation are frequently encountered and may lead to failure of endodontic therapy. To reduce these procedural errors and efficiently manage curved canals, various modifications in instrumentation technique and the design and flexibility of instruments have been advocated. This study compared the maintenance of the original canal curvature, cross sectional canal shape, and preparation time during instrumentation with stainless steel hand (K-Flexo) file, and nickel-titanium rotary files (Profile and Lightspeed). Thirty resin blocks with simulated curved canals of 20~25 degrees were used and divided into three groups of 10 each. In group 1, canals were instrumented using a quarter turn/pull technique with K-Flexofiles. Group 2 canals were prepared with rotary NiTi Profiles. Group 3 was prepared with rotary NiTi Lightspeed instrument. Before and after instrumentation, all canals were scanned using stereo microcope, FlexCam camera, and Photoshop 3.0 computer program. The results were as follows : 1. All groups showed some loss of canal curvature after instrumentation. Average loss of canal curvature was 8.6 degrees for K-Flexofile, 7.7 degrees for Profile, and 5.8 degrees for Lightspeed. Lightspeed exhibited significantly less curvature loss than K-Flexofile (p<0.05). 2. At the apical 1-mm level, Profile produced significantly rounder canals than Lightspeed (p<0.05). At the 3-mm level, Profile and Lightspeed exhibited significantly rounder canals than K-Flexofile (p<0.05). 3. Preparation with Lightspeed was significantly faster than Profile and K-Flexofile, and Profile was faster than K-Flexofile (p<0.05). 4. There was no significant difference in incidence of zipping between the hand K-Flexofile and rotary NiTi (Profile and Lightspeed) instruments. Most of apical canals were slightly widened near the apical foramen. As a results of this study, rotary NiTi instruments are superior to the K-Flexofile in regard to the maintenance of original canal curvature, cross-sectional shape and preparation time. But more investigations and studies should be needed to evaluate the ideal canal instrumentation.

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Effect of coloring agent on the color of zirconia (Coloring agent가 지르코니아 색조 재현성에 미치는 영향)

  • Kim, Kwanghyun;Noh, Kwantae;Pae, Ahran;Woo, Yi-Hyung;Kim, Hyeong-Seob
    • The Journal of Korean Academy of Prosthodontics
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    • v.55 no.1
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    • pp.18-25
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    • 2017
  • Purpose: The aim of this study was to evaluate the effect of two types of coloring agents and the number of application on the color of zirconia. Materials and methods: Monolithic zirconia specimens ($15.7mm{\times}15.7mm{\times}2.0mm$) (n = 33) was prepared and divided into 11 groups. Each experimental group was coded as a1-a5, w1-w5 according to the type of coloring agent and number of application. Specimens with no coloring agent applied were set as control group. The color difference of specimen was measured by using double-beam spectrophotometer, and calculated color difference (${{\Delta}E^*}_{ab}$), translucency parameter (TP). All data was analyzed with two-way ANOVA, multiple comparison $Sch{\acute{e}}ffe$ test, Pearson correlation and linear regression analysis. Results: As the number of application increased, values of $CIE\;L^*$ was decreased, but values of $CIE\;b^*$ was increased in both coloring agents. However, there was no significant difference on values of translucency parameter. The color difference range of each group was ${0.87{\Delta}E^*}_{ab}$ to ${9.43{\Delta}E^*}_{ab}$. Conclusion: In this study, type of coloring agent and the number of application did not affect the color difference of zirconia.

Comparison of Flexural Strength of Three-Dimensional Printed Three-Unit Provisional Fixed Dental Prostheses according to Build Directions

  • Park, Sang-Mo;Park, Ji-Man;Kim, Seong-Kyun;Heo, Seong-Joo;Koak, Jai-Young
    • Journal of Korean Dental Science
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    • v.12 no.1
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    • pp.13-19
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    • 2019
  • Purpose: The aim of this study was to compare the flexural strength of provisional fixed dental prostheses which was three-dimensional (3D) printed by several build directions. Materials and Methods: A metal jig with two abutment teeth and pontic space in the middle was fabricated. This jig was scanned with a desktop scanner and provisional restoration was designed on dental computer-aided design program. On the preprocessing software, the build angles of the restorations were arranged at $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ and support was added and resultant structure was sliced to a thickness of $100{\mu}m$. Processed restorations were printed with digital light processing type 3D printer using poly methyl meta acrylate-based resin. After washing and post-curing, compressive loading was applied at a speed of 1 mm/min on a metal jig fixed to a universal testing machine. The maximum pressure at which fracture occurred was measured. For the statistical analysis, build direction was set as the independent variable and fracture strength as the dependent variable. One-way analysis of variance and Tukey's post hoc analysis was conducted to compare fracture strength among groups (${\alpha}=0.05$). Result: The mean flexural strength of provisional restoration 3D printed with the build direction of $0^{\circ}$ was $1,053{\pm}168N$; it was $1,183{\pm}188N$ at $30^{\circ}$, $1,178{\pm}81N$ at $45^{\circ}$, $1,166{\pm}133N$ at $60^{\circ}$, and $949{\pm}170N$ at $90^{\circ}$. The group with a build direction of $90^{\circ}$ showed significantly lower flexural strength than other groups (P<0.05). The flexural strength was significantly higher when the build direction was $30^{\circ}$ than when it was $90^{\circ}$ (P<0.01). Conclusion: Among the build directions $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ set for 3D printing of fixed dental prosthesis, an orientation of $30^{\circ}$ is recommended as an effective build direction for 3D printing.

Precision Evaluation of Scanning the Digital Dental Abutment Impression and Dental Gypsum Model according to 3-dimensional Superimposing Different Skills (3차원 중첩 기술 차이에 따른 디지털 치과용 지대치 인상체 및 경석고 모형의 스캐닝 정밀도 평가)

  • Jeon, Jin-Hun
    • The Journal of the Korea Contents Association
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    • v.18 no.12
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    • pp.639-645
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    • 2018
  • The objective of this research was to compare the precision of scanning the digital abutment impression and gypsum model according to 3-dimensional superimposing different skills. There were made with the abutment impression and gypsum model of a maxillary 1st premolar, blue light scanner scanned to obtain the stereolithography (STL) file. After the same process was performed 10 more times without moving them on the scanner table about the abutment impression and gypsum model, respectively (n=11, per types). By superimposing the date of scanning the abutment impression and gypsum model used with no control and best-fit-alignment skills, 10 color-difference maps and root mean square (RMS) data were obtained. The independent t-test was performed to compare RMS data between the each other groups (${\alpha}=0.05$). In the scanning abutment impressions, $RMS{\pm}SD$ of no control, best-fit-alignment showed $6.86{\pm}0.94$, $5.04{\pm}0.24$. in the scanning gypsum model, $4.98{\pm}1.16$, $3.39{\pm}0.07$, all groups showed a significant difference (P<0.001). Trough the this study's result, not only best-fit-alignment but no control is used with digital dental computer-aided design/computer-aided manufacturing (CAD/CAM) research and clinical part.

A noninvasive esthetic treatment of isolated microdontia using new high-translucent cubic-phase zirconia (5Y-PSZ) laminate veneers: A case report (고투명도 입방정상 지르코니아(5Y-PSZ) 라미네이트를 이용한 왜소치의 비침습적 심미 수복 증례)

  • Ahn, Min-Zin;Ahn, Do-Gwan;Pyo, Se-Wook;Kim, Hee-Kyung
    • The Journal of Korean Academy of Prosthodontics
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    • v.57 no.3
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    • pp.263-270
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    • 2019
  • Current trends in restorative dentistry focus on improving the esthetics and keeping the sound dental tissues as long as possible. The aims of this case report were to describe the successful outcome of cubic-phase zirconia laminate veneers for a patient with isolated microdontia by using a digital workflow, and to describe their clinical implications. A 15-year-old female who had isolated microdontia in combination with spacing visited Ajou University Dental Hospital for esthetic treatment. In this case, 6 maxillary anterior teeth were restored with cubic-phase zirconia laminate veneers without tooth structure removal by using a digital impression, computer-aided design (CAD) software, and computer-aided manufacturing (CAM) procedures. At 6-month follow-up, no distinct mechanical and biological complications were detected and the prostheses exhibited satisfactory esthetics and functions. Due to its favorable tissue responses and enhanced translucency, cubic-phase zirconia can be a suitable strategy for a noninvasive esthetic approach.

Application of various digital technique on full mouth rehabilitation: A case report (디지털 기술을 활용한 전악 고정성 보철 수복 증례)

  • Bae, Min-Soo;Song, Kwang-Yeob;Ahn, Seung-Geun;Park, Ju-Mi;Lee, Jung-Jin;Seo, Jae-Min
    • The Journal of Korean Academy of Prosthodontics
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    • v.59 no.1
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    • pp.43-54
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    • 2021
  • Based on rapid improvement in digital fields, many advanced digital technologies are utilized in prosthodontic treatment. Especially, intraoral scanners and 3D printing technology are commonly used, and facial scanning technology is recently being attempted to be part of these digital routines. This case report aims to introduce a digital procedure using the intraoral scanner, facial scanner, and 3D printing technology to create definitive restorations, which are esthetic and harmonious with patient's face. From thoroughly evaluated full-mouth provisional restoration which was manufactured and fitted conventionally, definitive prostheses were fabricated using various digital technique. Stable occlusion with functionally and aesthetically satisfying results were achieved.

Implant-supported fixed prostheses with high-performance polymer (PEKK) abutments in partial edentulous patients: A case report (부분 무치악 환자에서 고기능성 폴리머(PEKK) 지대주를 이용한 임플란트 고정성 보철물 수복 증례)

  • Ha, Seung-Ryong
    • The Journal of Korean Academy of Prosthodontics
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    • v.59 no.1
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    • pp.71-78
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    • 2021
  • Implant treatment, which was first attempted in fully edentulous patients, is now widely used in partially edentulous, and a single tooth missing patients. Moreover, implant treatment has become an essential treatment modality in modern dentistry. The material of fabricating implant prostheses has also become more diverse than before, one of which is the use of high-performance polymers. The frequency of using high-performance polymers, which have been used in the medical field, is also increased in the dental field compared to the past. In the first case, a PEKK abutment and a PFG crown (cement-screw-retaining type) were fabricated in the lower left second premolar, and in the second case, a PEKK abutment and a monolithic zirconia crown (cement-screw-retaining type) were fabricated in the missing upper left first molar, and in the third case two PEKK abutments and a splinted PFM crowns (cement-screw-retaining type) were fabricated and connected to the upper right first and second molar implants. Through these procedures the patients obtained esthetically and functionally satisfactory results after 4 years of follow-up.

Fabrication of removable partial denture on scleroderma patient using 3-dimensional intraoral scanner (전신성 피부경화증 환자에서의 3차원 구강스캐너를 이용한 가철성 국소의치 제작 증례)

  • Kim, Ung-Gyu;Han, Jung-Suk;Yoon, Hyung-In;Yeo, In-Sung Luke
    • The Journal of Korean Academy of Prosthodontics
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    • v.59 no.1
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    • pp.116-125
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    • 2021
  • A three-dimensional (3D) intraoral scanner, which is one of the major developments in digital dentistry, is widely used in fixed prosthodontics. The application of intraoral scanner is now increasing in removable prosthodontics. Sclerotic change induced by scleroderma causes the limitation of mouth opening and multiple loss of the teeth. Conventional prosthodontic procedures are challenging for patients with this disease. This study showed a case of digital approach to the removable prosthodontic treatment of a patient who had the scleroderma and the consequent microstomia. At the provisional stage, the optical impression of patient's oral structures was digitally obtained. Using a 3D printer, the provisional dentures were fabricated. After extraction of hopeless tooth, the definitive digital impression was taken and the metal frameworks were fabricated, based on the data acquired from the impression. The definitive removable partial dentures were completed and delivered to the patient, who was satisfied with the prostheses.

Full mouth rehabilitation through re-establishment of occlusal plane in partially edentulous patient with reduced vertical dimension accompanied by loss of posterior occlusal support (구치부 교합지지 상실과 수직고경 감소를 동반한 부분 무치악 환자에서 교합평면 회복을 통한 완전구강회복 증례)

  • Cho, Young Eun;Leesungbok, Richard;Lee, Suk Won;Choi, Joseph June Sirk
    • The Journal of Korean Academy of Prosthodontics
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    • v.60 no.3
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    • pp.263-275
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    • 2022
  • The loss of posterior occlusal support leads to further complications such as collapsed occlusal plane and reduced vertical dimension, and it may cause problems such as facial appearance change, reduced chewing efficiency, and temporomandibular joint disorders. In such case, it is necessary to re-establish occlusal plane and vertical dimension properly through accurate diagnosis and predictable treatment plan. This case report presents a 71-year-old female, whose occlusal plane was collapsed and posterior restorative space was insufficient. To perform a patient-friendly full mouth rehabilitation, proper vertical dimension and occlusal plane were decided by evaluation of interocclusal space at her physiologic mandibular rest position, swallowing, pronunciation, facial appearance, and the average length of anterior teeth. And then, the fixed provisional restorations were fabricated with the new occlusal position, and evaluated for 5 months with checking adaptation of masticatory muscles and any kind of clinical symptoms occurs or not. After confirmation of functional stability and esthetic satisfaction with the newly established occlusion, final definitive restorations were fabricated and inserted in the mouth. Through the above process, the treatment result was functionally and aesthetically satisfactory.

Full mouth rehabilitation with fixed implant-supported prosthesis using temporary denture and double digital scanning technique: a case report (임시 의치와 이중 디지털 스캐닝 기법을 활용한 전악 고정성 임플란트 수복 증례)

  • Seok-Hyun Shin;Chan-Ik Park;Se-Ha Kang;Ji-Eun Moon;Min-Seok Oh;Chul-Min Park;Woo-Jin Jeon;Seong-Gu Han;Sun-Jae Kim;Su-Jin Choi
    • The Journal of Korean Academy of Prosthodontics
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    • v.61 no.3
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    • pp.245-256
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    • 2023
  • When restoring with a dental digital system for implant-supported prosthesis, a double digital scanning technique is required: an intraoral scan of the three-dimensional implant location and intraoral scan after placement of temporary denture or provisional prosthesis. During the intraoral scan, the use of scan body as a stable landmark can improve the accuracy of digital impression and simplify laboratory process. In this case, a full-digital system was used to plan and fabricate a custom abutment, provisional prosthesis, and definitive prosthesis. After implant placement, the scan area of the intraoral scan body connected with implant and the intraoral scan body marked on the inside of temporary denture were superimposed. Out of the superimposed files, a custom abutment and provisional prosthesis were fabricated which match the vertical dimension of temporary denture, and definitive prosthesis was fabricated based on provisional prosthesis. We report this case because result has been functionally and esthetically satisfactory by using vertical dimension and central relation set during the fabrication of temporary denture to the definitive prosthesis.