• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.653-664
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• 2007

Statement of problem: The screw detorque value is a measure of the preload remaining in the screw just before detorquing. Purpose: This study evaluated the effect of different screw tightening sequences and tightening methods on detorque values for a well-fitting implant superstructure. Material and method: An implant superstructure that connected directly to four implants (Astra Tech) was fabricated on a fully edentulous mandibular acrylic resin model. Six well-fitting dental stone casts were made with a pickup impression of the superstructure from the acrylic resin model. To evaluate the effect of three screw tightening sequences (1-2-3-4, 2-4-3-1, and 2-3-1-4) and two tightening methods (2-step and 1-step) on the stability of screw joint, the detorque values for a well-fitting implant superstructure were measured twice after screw tightening using 20 Ncm. Detorque values were analyzed using multi-way analysis of variance and two-way analysis of variance at a .05 level of significance. Results: 1. The mean detorque values for three screw tightening sequences were 12.3 Ncm, 12.6 Ncm, and 12.0 Ncm, respectively. 2. The mean detorque values for two screw tightening methods were 12.0 Ncm, and 12.2 Ncm, respectively. 3. The mean of mimimum detorque values for three screw tightening sequences and for two tightening methods were 10.6 Ncm, 11.1 Ncm, 10.5 Ncm, and 9.8 Ncm, respectively. 4. No statistically significant differences among the variables of screw tightening sequence and tightening method were found (p>.05) for detorque values and for mimimum detorque values. Conclusion: Within the limitations of this study, the screw tightening sequence and tightening method did not have a significant effect on the detorque values for a well-fitting implant superstructure.

• Journal of Periodontal and Implant Science
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• v.43 no.2
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• pp.58-63
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• 2013

Purpose: The aim of this study was to measure the peri-implant bone length surrounding implants that penetrate the sinus membrane at the posterior maxilla and to evaluate the survival rate of these implants. Methods: Treatment records and orthopantomographs of 39 patients were reviewed and analyzed. The patients had partial edentulism at the posterior maxilla and limited vertical bone height below the maxillary sinus. Implants were inserted into the posterior maxilla, penetrating the sinus membrane. Four months after implant insertion, provisional resin restorations were temporarily cemented to the abutments and used for one month. Then, a final impression was taken at the abutment level, and final cement-retained restorations were delivered with mutually protected occlusion. The complications from the implant surgery were examined, the number of failed implants was counted, and the survival rate was calculated. The periimplant bone lengths were measured using radiographs. The changes in initial and final peri-implant bone lengths were statistically analyzed. Results: Nasal bleeding occurred after implant surgery in three patients. No other complications were found. There were no failures of the investigated implants, resulting in a survival rate of 100%. Significantly more bone gain around the implants (estimated difference=-0.6 mm, P=0.025) occurred when the initial residual bone height was less than 5 mm compared to the >5 mm groups. No significant change in peri-implant bone length was detected when the initial residual bone height was 5 mm or larger. Conclusions: This study suggests that implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height may be safe and functional.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.273-281
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• 2001

Digital subtraction radiography may be one of the most precise and noninvasive methods for assessing subtle density changes in peri-implant bone, providing additional diagnostic information on implant tissue integration in overall maintenance. The aims of this study were to evaluate density changes after first, second surgery of dental implant and to measure the amount of marginal bone loss 9 months after second surgery using digital subtraction radiography. Bone change around 30 screw-shaped implants in 16 patients were assessed on radiographs. 17 Branemark implants of 3.75mm in diameter(Nobel Biocare, Goteborg, Sweden), 2 Branemark implants of 5.0mm in diameter, 11 $Replace^{TM}$ implants of 4.3mm in diameter(Nobel Biocare, Goteborg, Sweden) were used. To standardize the projection geometry of serial radiographs of implants, customized bite block was fabricated using XCP film holder(Rinn Corporation, Elgin, IL.) with polyether impression material of Impregum(ESPE, Germany) and direct digital image was obtained. Qualitative and quantitative changes on radiographs were measured with Emago software(The Oral Diagnostic System, Amsterdam, Netherlands). The results were as follows: 1. The peri-implant bone density of 69.2% implants did not change and the peri-implant bone density of 30.8% implants decreased after 3 months following first surgery. 2. The crestal bone density of 53.9% implants decreased first 3 months after second surgery. The crestal bone density of 58.8% implants increased 9 months after second surgery. No density change was observed around the midportion of the implants after second surgery, 3. The amount of marginal bone loss between different kinds of implants showed no statistically significant differences (p>0.05). 4. More than 90% of total marginal bone loss recorded in a 9-month period occurred during the first 3 months.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.50 no.2
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• pp.70-79
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• 2024

Objectives: The surgical guide is a static computer-assisted device used for implant surgery planning and guidance. By taking an impression and referring to the patients' three-dimensional computed tomography scan of the desired implant site, a surgical guide can be created. During surgery, the surgical guide aids in achieving the designed implant placement position and direction. We examined and evaluated the long-term clinical outcomes of implant surgery using surgical guides. Materials and Methods: This study investigated a total of 15 patients with 32 implants that were placed using surgical guides from 2009 to 2011 with a mean follow-up period extended beyond 10 years. Patient demographics and implant survival rates were recorded. We analyzed marginal bone loss (MBL) by assessing the radiographs acquired at installation, three months after installation, and one month, one, two, and five years after prosthesis delivery. Results: The mean patient age was 57.33 years at implant placement. Of the 32 implants, five implants were placed in the anterior region and 27 implants were in the posterior region. Six implants failed and three of them were replaced, resulting in an 81.25% survival rate. The mean follow-up period was 10 years and nine months. Mean MBL compared to post-installation was significantly higher than at three months after installation, and one month, one, two, and five years after prosthesis delivery. Mean MBL at three months after installation, and one month, one year, and two years were significantly higher compared to the previous visit (P<0.05). However, MBL at five years after prosthesis delivery did not differ significantly compared to at two years. Conclusion: In this study, implant rehabilitation assisted by surgical guides exhibited favorable survival rates. With the limitation of the sample amount in this study, further research and more samples are required to evaluate the long-term clinical effectiveness of surgical guides.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.1
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• pp.43-48
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• 2003

During the past several years, significant advances have occurred in the utilization of osseointegrated implants for the treatment of partially edentulous patients. One of the biggest purposes for treating of these patients is the high demand for improved esthetics, especially in the anterior region. For this esthetics, the new trend in dental implants is the immediate placement and immediate superstructure fabrication. The refined surgical technique, the skillful soft tissue management, and the proper prosthetic coordination are the main factors to achieve natural looking of implant supported prosthesis. The customized provisional restoration and the customized impression coping are recommended for the optimal peri-implant soft tissue contour. The basic concept of Frialit 2 system was the immediate replacement of a tooth with root-analog fixture after extraction. This system guarantees an ideal result in function and esthetics. The ceramic abutment system offers improved quality in the respect of esthetics, fitness, translucency, and biocompatibility. In this clinical report, the final restoration made with IPS Empress 2 crown on the CeraBase abutmen of Frialit 2 system allowed the reproduction of the natural vitality of tooth and adjacent gingiva.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.175-184
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• 2011

With a development of implant restoration technique, there are increasing use of computer-guided system for edentulous patients. It was carried out simulated operation based on CT information about patient's bone quantity, quality and anatomical landmark. However, there are some difference between the programmed implant and post-operative implant about it's position. If the deviation was severe, it could happen a failure of 'passive fit' and not suited for path of implant restoration. The aim of this presentation is to evaluate about a degree of deviations between programmed implant and post-operative implant. Five patients treated by 'NobelGuide' system (Nobel Biocare AB, G$\ddot{o}$teborg, Sweden) in Department of Prosthodontics, Inha University were included in this study. The patients were performed CT radiograph taking and intra-oral impression taking at pre-operation. Based on CT images and study model, surgical stent was produced by NobelBiocareTM. To fabricated a pre-operative study model, after connected lab analog to surgical template, accomplished a pre-operative model using type 4 dental stone. At final impression, a post-operative study model was fabricated in the conventional procedures. Each study model was performed CT radiograph taking. Based on CT images, each implant was simulated in three dimensional position using $Procera^{(R)}$ software (Procera Software Clinical Design Premium, version 1.5; Nobel Biocare AB). In 3D simulated model, length and angulation between each implant of both pre- and post-operative implants were measured and recorded about linear and angular deviation between pre-and post-operative implants. A total of 24 implants were included in this study and 58 inter-implant sites between each implant were measured about linear and angular deviations. In the linear deviation a mean deviation of 0.41 mm (range 0~1.7 mm) was reported. In the angular deviation, a mean deviation was $1.99^{\circ}$ (range $0^{\circ}{\sim}6.7^{\circ}$). It appears that the both linear and angular mean deviation value were well acceptable to application of computer-guided implant system.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.30.1-30.6
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• 2016

Background: The prognosis of wide implants tends to be controversial. While wider implants were initially expected to result in a larger osseointegration area and have higher levels of primary stability, they were reported to have a relatively high rate of failure. The clinical outcome of ultrawide implants of more than 6 mm in diameter was evaluated through a retrospective study. Methods: The investigation was conducted on patients who had received ultrawide implant (${\geq}6mm$ diameter) placements in Seoul National University Bundang Hospital from January 2008 to December 2013. Complications were investigated during the maintenance period, and marginal bone loss was measured using periapical radiography. Primary stability immediately after the implant placement and second stability after second surgery or during impression were measured using $Osstell^{(R)}$ Mentor (Osstell, Sweden) as an implant stability quotient (ISQ). Results: Fifty-eight implants were placed in 53 patients (30 male, 23 female), and they were observed for an average of $50.06{\pm}23.49$ months. The average ISQ value increased from $71.22{\pm}10.26$ to $77.48{\pm}8.98$ (P < 0.005). The primary and secondary stability shows significantly higher at the mandible than at the maxilla (P < 0.001). However, mean survival rate shows 98.28 %. Average marginal bone loss of 0.018 and 0.045 mm were measured at 12 and 24 months after the loading and 0.14 mm at final follow-up date (mean 46.25 months), respectively. Also in this study, the bone loss amount was noticeably small compared to regular implants reported in previous studies. Conclusions: The excellent clinical outcome of ultrawide implants was confirmed. It was determined that an ultrawide implant can be used as an alternative when the bone quality in the posterior teeth is relatively low or when a previous implant has failed.

• Journal of Technologic Dentistry
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• v.43 no.4
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• pp.202-209
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• 2021

By classifying temporary denture production for surgical guides, digital guide-based surgery, and final prosthesis production, the problems of each process were assessed in advance and the factors that could be improved were confirmed in this study. The manufacturing process of fusion dental prosthesis uses virtual programs and computed tomography images to manufacture devices using the latest technologies of computer-aided design/computer-aided manufacturing and three-dimensional printing, which enables implants to be placed in the desired location in advance. Moreover, implant placement is not dependent on the skill and condition of the dentist, and because it uses a computer system, it can always be performed at a constant and optimal position. This can reduce the remanufacturing rate compared with the general method, shorten the treatment period, and eliminate patient discomfort. Unlike the traditional method of using impression materials and plaster models, digital fusion dental prostheses would be evaluated as a technology for producing prosthesis through professional design technology and communication.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.459-468
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• 2021

In patients with myasthenia gravis, it is difficult to manufacture and maintain dentures because the muscles and nervous system in the oral cavity are not properly adjusted. In addition, excessively extended or thick dentures may cause muscle weakness by stimulating the muscles, so dentures should be manufactured in consideration of this. In this case, a denture was fabricated using the closed mouth technique in a patient with myasthenia gravis with mouth opening limitation. Using the closed mouth technique, the patient's masticatory pressure and muscle movements were reproduced and denture with good retention were manufactured.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.298-305
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• 2016

The maxillary anteriors play an important role in esthetics. Therefore after extraction, it is crucial to preserve the hard tissue and soft tissue in order to promote esthetics of restoration. There are several challenges when restoring the maxillary anteriors via implant. Some of the challenges are be maintaining consistency with neighboring teeth in terms of shade, form, and texture : as well as having harmonious emergency with the gingival margin. In this case, a traumatized patient with crown-root fracture of the maxillary central and lateral incisors is presented. The cracked teeth were extracted, and implants were inserted with bone grafts to compensate the volume of damaged area of the maxillary anterior. Cantilever implant prosthetics were planned while precise adjustments to the gingival area were made using customized impression coping to perform the esthetic restorations. The final outcome of the treatment was satisfying in both esthetic and utilitarian perspective.