• The Journal of Advanced Prosthodontics
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• 제9권1호
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• pp.14-21
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• 2017

PURPOSE. The aim of this study was to compare the retention of mini implant overdenture by the number, the type of magnetic attachment, and the directions of applied dislodging force. MATERIALS AND METHODS. The experimental groups were designed by the number and type of magnetic attachment. Twenty samples were tested with Magden implants. Each attachment was composed of the magnet assembly in overdenture sample and the abutment keeper in a mandibular model. Dislodging forces were applied to the overdenture samples (50.0 mm/min) in 3 directions. The loading was repeated 10 times in each direction. The values of dislodging force were analyzed statistically using SPSS at 95% level of confidence. RESULTS. The retentive force of group 2 was greater than that of group 1 in both types of attachment in every direction (P < .05). Oblique retentive force of flat type magnetic attachment was higher than that of cushion type attachment in both groups (P < .05). In group 1, oblique retentive force showed the highest and anterior-posterior retentive force showed the lowest value in both attachment types (P < .05). In group 2, both types of attachment showed the lowest retentive force with anterior-posterior direction of dislodging force (P <.05). CONCLUSION. Proper retentive properties for implant overdenture were obtained, regardless of the number and type of magnetic attachment. In both types of magnetic attachment, the greater retentive force was attained with more implants. Oblique retentive force of flat type magnetic attachment was greater than that of cushion type. Among all subgroups, anterior-posterior retentive force was the lowest among three different directions of dislodging force.

• Journal of Periodontal and Implant Science
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• 제50권2호
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• pp.97-105
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• 2020

Purpose: The present retrospective clinical study aimed to evaluate and compare the clinical and radiographic parameters, complications, and satisfaction in patients who received fixed prostheses supported by narrow-diameter implants (NDIs) in the anterior and posterior jaw. Methods: Patients aged ≥30 years who had NDI-supported fixed prostheses in the anterior or posterior region of either jaw for at least 2 years were included. Complications such as chipping of the crown; loosening or fracture of the screw, crown abutment, or implant; and loss of retention were recorded. Clinical peri-implant outcomes and crestal bone loss (CBL) were measured. A questionnaire was used to record responses regarding the aesthetics and function of the fixed restorations. Analysis of variance was used to assess the significance of between-group mean comparisons. The log-rank test was performed to analyze the influence of location and prosthesis type on technical complications. Results: Seventy-one patients (mean age: 39.6 years) provided informed consent with a mean follow-up duration of 53 months. Only bleeding on probing showed a statistically significant difference between NDIs in the anterior and posterior regions. The complication rate for NDIs in the posterior region was significantly higher than that for NDIs in the anterior region (P=0.041). For NDIs, CBL was significantly higher around splinted crowns than single crowns (P=0.022). Overall mean patient satisfaction was 10.34±3.65 on a visual analogue scale. Conclusions: NDIs in the anterior and posterior jaws functioned equally well in terms of periimplant soft and hard tissue health and offered acceptable patient satisfaction and reasonable complication rates.

• 대한치과보철학회지
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• 제35권4호
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• pp.793-800
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• 1997

Periotest(Siemens, Germany) has been used to test mobility of the implants clinically, however the effects of target materials and connection methods on the PTVs(Periotest Values) have not been evaluated. Periotest has been regarded as a reliable and objective tool to test implant and natural teeth mobility clinically, however this instrument showed different PTVs under various test conditions. This in vitro study was designed to compare PTVs of different veneering materials and prosthodontic designs (single and bridge restorations). To compare the effects of veneering materials on PTVs, 1 mm thickness of five different testing materials (porcelain, type III gold alloy, pure titanium, composite resin, acrylic resin) were placed on the resin block. Three full length of 13 mm Mark II implant fixtures were embedded into autopolymerizing resin block to fabricate single and bridge restorations. To evaluate effects of the connection method in single restorations, PTVs of screw retained(UCLA type) and cementation type(Cera-One system) were compared. Finally, to test reliability of PTVs of the final restorations, screw retained three unit short span PFM bridges were fabricated on the standard and Estheti-Cone abutments. All testing components were tightened with torque controller and PTVs of all specimens were measured 15 times for statistical analysis with SAS program. Following conclusions were made within the limit of this in vitro study. 1. PTVs of type III gold alloy, grade II titanium, composite resin veneering materials showed no significant differences, however acrylic resin and porcelain showed significant differences (P<0.05). 2. Single tooth restorations showed consistent PTVs as long as proper torque force was applied. 3. PTVs of bridge type prostheses was inconsistent regardless of abutment types. 4. PTVs of the prostheses showed higher scores and standard deviations than those of abutments regardless types of connection (P<0.05).

• 대한치과보철학회지
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• 제37권6호
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• pp.825-834
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• 1999

Recently, various implant cylinders were supplied. especially received gold cylinders, cast cylinders produced from premade gold and plastic cylinders and plastic cylinders. This study measured and compared precise fit produced when using conventional gold and plastic cylinders. The comparative fit of lapped and non-lapped castings made from plastic pattern was examined. The implant/abutment interface fit was evaluated by scanning electron microscopy(SEM) for each of four cylinders. The following results were obtained: 1. The case of plastic cylinder showed $9.67{\pm}1.50{\mu}m$ gap when Steri-Oss fixture was connected. 2. The case of lapped casting made from plastic cylinder showed $3.01{\pm}2.81{\mu}m$ gap when Steri-Oss fixture was connected. 3 The case of gold/plastic cylinder showed $9.80{\pm}1.68{\mu}m$ gap when Steri-Oss fixture was connected. 4. The case of gold cylinder showed ${5.47{\pm}2.43\mu}m$ gap when Steri-Oss fixture was connected. 5. In case of each cylinder which was connected with Steri-Oss fixture, the size of gap was showed less in the order of the case of gold/plastic cylinder, the case of plastic cylinder, the case of gold cylinder and the case of lapped casting made from plastic cylinder As results of this study, the use of premade gold cylinder offers an advantage over plastic pat-terns in precise fit. When plastic patterns are used, polishing of implant cylinder components should provide precise fit.

• Journal of Periodontal and Implant Science
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• 제40권5호
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• pp.244-248
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• 2010

Purpose: The purpose of this study was to radiographically evaluate marginal bony changes in relation to different vertical positions of dental implants. Methods: Two hundred implants placed in 107 patients were examined. The implants were classified by the vertical positions of the fixture-abutment connection (microgap): 'bone level,' 'above bone level,' or 'below bone level.' Marginal bone levels were examined in the radiographs taken immediately after fixture insertion, immediately after second-stage surgery, 6 months after prosthesis insertion, and 1 year after prosthesis insertion. Radiographic evaluation was carried out by measuring the distance between the microgap and the most coronal bone-to-implant contact (BIC). Results: Immediately after fixture insertion, the distance between the microgap and most coronal BIC was $0.06{\pm}0.68\;mm$; at second surgery, $0.43{\pm}0.83\;mm$; 6 months after loading, $1.36{\pm}0.56\;mm$; and 1 year after loading, $1.53{\pm}0.51\;mm$ ($mean{\pm}SD$). All bony changes were statistically significant but the difference between the second surgery and the 6-month loading was greater than between other periods. In the 'below bone level' group, the marginal bony change between fixture insertion and 1 year after loading was about 2.25 mm, and in the 'bone level' group, 1.47 mm, and in 'above bone level' group, 0.89 mm. Therefore, the marginal bony change was smaller than other groups in the 'above bone level' group and larger than other groups in the 'below bone level' group. Conclusions: Our results demonstrated that marginal bony changes occur during the early phase of healing after implant placement. These changes are dependent on the vertical positions of implants.

• 대한치과보철학회지
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• 제35권2호
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• pp.308-329
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• 1997

A lot of the research paper was reported about the result of influence of IMC (Intra-mobile connector) in the IMZ implant placed solely in the alveolar bone, but reports about the effect of IMC on functional load at state of connecting with natural teeth ere rare. The major propose of this study was find the mechanical character of IMC itself by using the finite element analysis program after simulated variance of condition connected with the natural teeth and implant on funcional load. When first and second premolar was lost, IMZ implant was placed with a diameter of 3.3mm and a length of 13mm with IMC in second premolar area. Rigid connection was done and the non-figid connention was located on the female part of the canine abutment and the implant respectively and then both the infraocclusion of $30{\mu}m$ and the non-infraocclusion under the load of 40kg applied to the portion of the natural teeth, the pontic and the implant. The displacement and the stress of it was estimated and analyzed IMC itself of the rigid connection and the non-rigid connection was grouped. The following result were obtained. 1. In all groups, the displacement of Y-axis was greater than that of X-axis and the aspect of displacement showed that IMC was displaced downward and to the center. 2. There was no differences in the displacement of IMC regardless of the connection type. 3. In the displacement of IMC, I 4 was the least, I 1 and I 3 are similar and I 2 was the greatest. 4. There was no differences in the peak value of maximal stress of IMC regardless of the connection type. 5. In the peak value of maximal stress of IMC, I 4 was the least, I 1 and I 3 were similar, and I 2 was the largest.

• 대한치과보철학회지
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• 제44권4호
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• pp.421-431
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• 2006

Statement of problem : Accurate impression is essential to success of implant prostheses. But there have been few studies about the accuracy of fixture-level impression technique in internal connection implant system. Purpose: This study evaluated the accuracy of splinted fixture-level impression technique using clinical methods and the effect of internal hex on fit of superstructure in internal connection implant system (Astra Tech). Material and method : Two metal master frameworks made from two abutments (Cast-to Abutment ST) each for parallel and divergent conditions and a corresponding. passively fitting, dental stone master cast with four future replicas (Fixture Replica ST) were fabricated. Ten dental stone casts were made with vinyl polysiloxane impressions from the master cast by acrylic resin splinted fixture-level impression technique. To evaluate the accuracy of impression technique, the fit of master frameworks for test models was evaluated using screw resistance test (SRT) and one-screw test. The results of SRT were recorded as SRT values from grade 1 to grade 5 by 1/4 turn. And to evaluate the effect of hex on fit of superstructure, the same tests were performed after removing hexes of master frameworks. Results: 1. There was only one case (2.5%) showing SRT value of test model below ade 2 in total before and after removing hexes of master frameworks. And, by removing hexes. SRT values decreased in only one test model (5%) and did not change in 17 test models (85%). 2. SRT values of the 1$^{st}$ screws were grade 2 in 80% of cases before, and grade 1 in 80% of cases after removing hexes. And, by removing hexes, SRT values decreased in 72.5% of cases. 3. SRT values of the 2$^{nd}$ screws were grade 3 in 85% of cases before, and grade 3 in 95% of cases after removing hexes. And, by removing hexes, SRT values did not change in 85% of cases. 4. There were only 2 cases regarded as acceptable fit by one-screw test, and SRT values of 2$^{nd}$ screws of both cases were grade 2. Conclusion. Within the limitations of this study, future-level impression of internal connection implant system is considered to obtain inaccurate working cast, even using acrylic resin splinted impression technique. And, it is considered to be unable improve the fit to remove the hexes of implant restoration.

• Journal of Periodontal and Implant Science
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• 제40권4호
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• pp.194-200
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• 2010

Purpose: There is no consensus regarding the relationship between the width of keratinized mucosa and the health of periimplant tissues, but clinicians prefer to provide enough keratinized mucosa around dental implants for long-term implant maintenance. An apically positioned flap during second stage implant surgery is the chosen method of widening the keratinized zone in simple procedures. However, the routine suture techniques used with this method tend to apply tension over the provisional abutments and decrease pre-existing keratinized mucosa. To overcome this shortcoming, a pre-fabricated implant-retained stent was designed to apply vertical pressure on the labial flap and stabilize it in a bucco-apical direction to create a wide keratinized mucous zone. Methods: During second stage implant surgery, an apically displaced, partial thickness flap with a lingualized incision was retracted. A pre-fabricated stent was clipped over the abutments after connecting to the provisional abutment. Vertical pressure was applied to displace the labial flap. No suture was required and the stent was removed after 10 days. Results: A clinically relevant amount of keratinized mucosa was achieved around the dental implants. Buccally displaced keratinized mucosa was firmly attached to the underlying periosteum. A slight shrinkage of the keratinized zone was noted after the healing period in one patient, but no discomfort during oral hygiene was reported. Clinically healthy gingiva with enough keratinized mucosa was achieved in both patients. Conclusions: The proposed technique is a simple and time-effective technique for preserving and providing keratinized tissue around dental implants.

• 구강회복응용과학지
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• 제29권3호
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• pp.259-271
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• 2013

임플란트 고정체-지대주 결합구조체의 형태에 따른 교합부하의 반응이 다양하여 본 연구에서는 하중위치 및 결합구조체 접촉 비율에 따라 3단 계단형 결합구조체와 경사형에서 어떠한 차이가 있는 지를 3차원 유한요소분석을 시행하였다. 2종의 임플란트-지대주 결합 구조체에 연결된 상부 치관을 제작하여 각 치관에 설정된 하중위치에 200 N의 하중을 부여하였다. 임플란트 중심 부위에서 하중조건이 멀어질수록 피질골정에 가해지는 응력이 증가되기에 하중조건은 응력발생에 영향을 미치는 주요 요소이며 다음으로 결합구조형태에도 영향을 받았다. 또한 수직 하중에 비해 빗금 경사 하중이 부여된 경우 계단형은 경사형에 비해 유리한 응력 분포를 보였다. 그리고 지대주 결합구조체가 고정체의 내벽에 대해 접촉이 많아 질수록 골질에 대한 응력분산이 유리한 것으로 나타났다. 결론적으로 고정체 폭경에서 벗어난 빗김 수직 및 경사 하중은 결합구조체의 종류와 관계없이 피질골정에 응력을 집중시키므로 저작기능시 교합접촉면을 고정체의 폭경 내에 위치하도록 하는 것이 생체역학적으로 바람직 할 것으로 사료되었다.

• 대한치과보철학회지
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• 제60권2호
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• pp.168-174
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• 2022

상악 전치부의 임플란트 식립 시 치은 퇴축이나 골 결손 문제를 동반하는 경우에는 심미적인 임상 결과를 얻기가 쉽지 않다. 본 증례에서는 상악 우측 중절치에서 순측 치조골판의 소실이 진단되어 발치 후 연조직을 확보한 후에 골 이식을 동반하는 임플란트 식립을 계획하였다. 또한 이상적인 임플란트 식립 위치를 위해 디지털 가이드 수술을 시행하였고, 치조골 결손부가 광범위하기 때문에 하악지에서 자가골 채취 후 이종골과 함께 골유도재생술을 동반하였다. 충분한 임플란트의 골 유착 기간을 거친 뒤 2차 수술 및 인상 채득을 통한 임시 보철물을 제작하였고, 주기적인 외형 조정을 통해 연조직의 형태를 개선하였다. 최종 보철물 제작시에는 양극 처리를 시행한 맞춤형 지대주를 사용하여 자연 치아의 색조를 유도하였고, 구강 스캔을 통하여 임시 보철물의 형태를 재현해 줌으로써 심미적이고 기능적인 지르코니아 보철물을 장착해 주었다.