• Journal of Periodontal and Implant Science
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• v.53 no.5
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• pp.376-387
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• 2023

Purpose: Peri-implantitis (PI) is an inflammatory condition associated with the destruction of bone tissue around a dental implant, and diode lasers can be used to treat this disease. In this study, we aimed to evaluate the effectiveness of a 940-nm diode laser for the nonsurgical treatment of PI. Methods: Twenty patients (8 women and 12 men) were enrolled in a split-mouth randomized controlled study. In the control group (CG), mechanical debridement with titanium curettes accompanied by airflow was performed around the implants. The test group (TG) was treated similarly, but with the use of a diode laser. Clinical measurements (plaque index, gingival index [GI], probing pocket depth [PPD], bleeding on probing [BOP], clinical attachment level, and interleukin-1β [IL-1β] in the peri-implant crevicular fluid) were evaluated and recorded at baseline and 3 months. IL-1β levels were determined using the enzyme-linked immunosorbent assay method. Results: The symptoms were alleviated in both groups at 3 months as assessed through clinical measurements. GI, BOP, and PPD were significantly lower in the TG than in the CG (P<0.05). The IL-1β level increased post-treatment in both groups, but this increase was only statistically significant (P<0.05) in the CG. Conclusions: The diode laser enabled improvements in clinical parameters in the periimplant tissue. However, it did not reduce IL-1β levels after treatment. Further studies about the use of diode lasers in the treatment of PI will be necessary to evaluate the effects of diode lasers in PI treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.4
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• pp.283-305
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• 2001

The purpose of this study was to analyze the stress distribution of condylar regions and edentulous mandible with implant-supported cantilever prostheses on the certain conditions, such as amount of load, location of load, direction of load, fixation or non-fixation on the condylar regions. Three dimensional finite element analysis was used for this study. FEM model was created by using commercial software, ANSYS(Swanson, Inc., U.S.A.). Fixed model which was fixed on the condylar regions was modeled with 74323 elements and 15387 nodes and spring model which was sprung on the condylar regions was modeled with 75020 elements and 15887 nodes. Six Br${\aa}$nemark implants with 3.75 mm diameter and 13 mm length were incorporated in the models. The placement was 4.4 mm from the midline for the first implant; the other two in each quardrant were 6.5 mm apart. The stress distribution on each model through the designed mandible was evaluated under 500N vertical load, 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. The load points were at 0 mm, 10 mm, 20 mm along the cantilever prostheses from the center of the distal fixture. The results were as follows; 1. The stress distribution of condylar regions between two models showed conspicuous differences. Fixed model showed conspicuous stress concentration on the condylar regions than spring model under vertical load only. On the other hand, spring model showed conspicuous stress concentration on the condylar regions than fixed model under 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. 2. Fixed model showed stress concentration on the posterior and mesial side of working and balancing condylar necks but spring model showed stress concentration on the posterior and mesial side of working condylar neck and the posterior and lateral side of balancing condylar neck under vertical load. 3. Fixed model showed stress concentration on the posterior and lateral side of working condylar neck and the anterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior sides of working and balancing condylar necks under horizontal load linguobuccally. 4. Fixed model showed stress concentration on the posterior side of working condylar neck and the posterior and lateral side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 20 degree oblique load. 5. Fixed model showed stress concentration on the anterior and lateral side of working condylar neck and the posterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 45 degree oblique load.. 6. The stress distribution of bone around implants between two models revealed difference slightly. In general, magnitude of Von Mises stress was the greatest at the bone around the most distal implant and the progressive decrease more and more mesially. Under vertical load, the stress values were similar between implant neck and superstructure vertically, besides the greatest on the distal side horizontally. 7. Under horizontal load linguobuccally, buccal 20 degree oblique load and buccal 45 degree oblique load, the stress values were the greatest on the implant neck vertically, and great on the labial and lingual sides horizontally. After all, it was considered that spring model was an indispensable condition for the comprehension of the stress distributions of condylar regions.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.292-298
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• 2012

Purpose: The purpose of this study is to ascertain the stability of the implant by comparing the effects of the change of implant diameter, length and design on implant stability quotient. Materials and methods: To remove the variable due to the difference of bone quality, the uniform density (0.48 g/$cm^3$) Polyuretane foam blocks (Sawbones$^{(R)}$, Pacific Research Laboratories Inc, Vashon, Washington) were used. Implants (Implantium$^{(R)}$, Dentium, Seoul, Korea) were placed with varying diameters (${\phi}3.8$, ${\phi}4.3$ and ${\phi}4.8$) and length (8 mm, 10 mm and 12 mm), to assess the effect on implant stability index (ISQ). Also the influence of the design of the submerged and the non-submerged (SimplelineII$^{(R)}$, Dentium, Seoul, Korea) on ISQ was evaluated. To exclude the influence of insertion torque, a total of 60 implants (n = 10) were placed with same torque to 35 N. Using Osstell$^{TM}$ mentor (Integration Diagnostic AB, Sweden) ISQ values were recorded after measuring the resonant frequency, one-way ANOVA and Tukey HSD test results were analyzed. (${\alpha}$=0.05). Results: 1. The change of the diameter of the implant did not affect the ISQ (P>.05), but the increase of implant length increased the ISQ(P<.001). 2. The change in implant design were correlated with the ISQ, and the ISQ of submerged design was significantly higher than that of the non-submerged design(P<.05). Conclusion: In order to increase implant stability, the longer implant is better to be selected, and on the same length of implant, submerged design is thought to be able to get a higher ISQ than the non-submerged.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.8-17
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• 2019

Purpose: The study analyzed the prevalence of peri-implantitis and factors which may have affected the disease. Materials and methods: This study based on medical records and radiographs of 422 patients (853 implant cases) who visited Ewha Womans University Mokdong Hospital Dental Center from January 1, 2012 to December 31, 2016. Generalized estimation equations (GEE) was utilized to determine the statistical relationship between peri-implantitis and each element, and the cumulative prevalence of peri-implantitis during the observation period was obtained by using the Kaplan Meier Method. Results: The prevalence rate of peri-implantitis at the patient level resulted in 7.3% (31 patients out of a total of 422 patients), and at the implant level 5.5% (47 implants out of a total of 853 implants). Sex, GBR, guided bone regeneration (GBR) and functional loading periods had statistical significance with the occurrence of peri-implantitis. Upon analysis of the cumulative prevalence of peri-implantitis in terms of implant follow-up period, the first case of peri-implantitis occurred at 9 months after the placement of an implant, and the prevalence of peri-implantitis showed a non-linear rise over time without a hint of a critical point. Conclusion: The prevalence of peri-implantitis at the patient level and the implant were 7.3% and 5.5%, respectively. Male, implant installed with GBR and longer Functional Loading Periods were related with the risk of peri-implantitis.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.157-168
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• 2008

Statement of problem: Over the past two decades, implant supported fixed prosthesis have been widely used. However, there are few studies conducted systematically and intensively on the splinting effect of implant systems in mandible. Purpose: The purpose of this study was to investigate the changes in stress distributions in the mandibular implants with splinting or non-splinting crowns by performing finite element analysis. Materials and methods: Cortical and cancellous bone were modeled as homogeneous, transversely isotropic, linearly elastic. Perfect bonding was assumed at all interfaces. Implant models were classified as follows. Group 1: $Br{{\aa}}nemark$ length 8.5mm 13mm splinting type Group 2: $Br{{\aa}}nemark$ length 8.5mm 13mm Non-splinting type Group 3: ITI length 8.5mm 13mm splinting type Group 4: ITI length 8.5mm 13mm Non-splinting type An load of 100N was applied vertically and horizontally. Stress levels were calculated using von Mises stresses values. Results: 1. The stress distribution and maximum von Mises stress of two-length implants (8.5mm, 13mm) was similar. 2. The stress of vertical load concentrated on mesial side of implant while the stress of horizontal load was distributed on both side of implant. 3. Stress of internal connection type was spreading through abutment screw but the stress of external connection type was concentrated on cortical bone level. 4. Degree of stress reduction was higher in the external connection type than in the internal connection type.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.271-300
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• 1993

The purpose of this study was to analyze the stress distribution at supporting bone according to the types of connection modality between implant and tooth in the superstrcture. This investigation evaluated the stress patterns in a photoelastic model produced by three different types of dental implants such as Branemark, Steri-Oss, IMZ and resin tooth using the techniques of quasi three dimensional photoelasticity. The teeth-supported bridge had a first molar pontic supported by second premolar and second molar as a control group. The implant and toothsupported bridge had a first molar pontic supported by second premolar and implant posterior retainer as an experimental group. Prostheses were mechanically connected to an adjacent second premolar by the rigid of nonrigid connection, Nonrigid connection used an attachment placed between the tooth-supported and fixture-supported component. The female(keyway) of attachment was placed on the distal end of the retainer supported by the tooth ; the male(Key) of attachment connected to the osseointegrated bridge was engaged into the keyway. All prostheses were casted in the same nonprecious alloy and were cemented and screwed on their respective abutments and implants. 16㎏ of vertical loads on central fossae of second premolar, first molar pontic, implant of second molar were applied respectively and 6.5㎏ of inclined load on middle buccal surface of first molar pontic was applied. The results were as follows : 1. Under the vertical load on the central fossa of first mloar pontic, the stress developed at the apex of tooth of implat was more uniformly distributed in the case of nonrigid connection than in the case of rigid connection. 2. Under the vertical load on the central fossa of first molar pontic, the stress developed around the cervical area of tooth of implant was larger in the case of rigid connection than in the case of nonrigid connection because the bending moment was more occured in the case of rigid connection than in the case of nonrigid connection. 3. Stress was more restricted to the loaded side of nonrigid connection than to that of rigid connection 4. Under the inclined load. The set screw loosening of implant was more easily occured in the case of nonrigid connection than in the case of rigid connection due to torque moment. 5. In the case of Branemark implant, the stress concentration in second premolar was larger and the stress developed around the cervical area of implant was lower than any other cases under the vertical load, because Branemark implant with the flexible gold screw was showed in incline toward second premolar by a bending moment. 6. The stress developed around the apex of tooth or implant was more uniformly distributed in the case of Steri-Oss implant with stiff screw than in the case of Branemark implant under the vertical load. But, the stress developed around the cervical area of the Steri-Oss implant was larger than that of any other implants because bending moment was occured by vertical migration of second premolar. 7. The stress distribution in the case of IMZ implant was similar to the case of natural teeth under small vertical load. But, the residual stress around the implant was showed to occurdue to deformation of IMC and sinking of screw under larger vertical load.

• 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.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.70-79
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• 2020

Purpose: The purpose of this study was to evaluate the effect of attachments and palatal coverage on stress distribution in maxillary implant overdenture using finite element analysis. Materials and Methods: Four maxillary overdenture 3-D models with four implants placed in the anterior region were fabricated with computer-aided design. 1) Ball-F: Non-splinted ball attachment and full palatal coverage, 2) Ball-P: Non-splinted ball attachment and U-shaped partial palatal coverage, 3) Bar-F: Splinted milled bar attachment and full palatal coverage, 4) Bar-P: Splinted milled bar attachment and U-shaped partial palatal coverage. Stress distribution analysis was performed with ANSYS workbench 14. 100 N vertical load was applied at the right first molar unilaterally and maximum stress was calculated at the implant, peri-implant bone and mucosa. Results: The use of the ball attachment showed lower maximum stress on implant and peri-implant bone than the use of the milled bar attachment. But it showed contrary tendency in the mucosa. Regardless of attachment, full palatal coverage showed lower maximum stress on implant, peri-implant bone and mucosa. Conclusion: Within the limitation of this study, ball attachment improved stress distribution on implant and peri-implant bone rather than milled bar attachment in maxillary implant overdenture. Also, full palatal coverage is more favorable in stress distribution.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.254-262
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• 2011

Purpose: This study aims to evaluate and prospect for current research trend and developmental perspectives via analyzing recent biomaterial coated-implants study. Materials and methods: To investigate each subject respectively, several biomaterials that are using for implant surface coating were set as 'keywords'. By these keywords, major research groups in each subject were chosen, and research trend of them was analyzed. Trend of In vivo studies that examined selected biomaterials were analyzed to evaluate commercial potential. Results: The collagen research accounted for 40% of total implant study, which was the highest, and fibronectin, BMPs (bone morphogenetic proteins) and RGD (Arg-Gly-Asp) peptides followed, which were ranked in descending order. Furthermore, figures of all four research subjects were also increased with time, especially a sharp increase in RGD research. According to the results of major research group, collagen that was combined with other organic and inorganic biomaterials was mostly examined, rather than using collagen only. Major research groups investigating BMPs mostly focused on rhBMP-2. In animal studies, collagen was used as resorbable membrane in guided bone regeneration (GBR) or drug carrier, while BMPs were used with bone graft materials or coating material for titanium implant surface. Conclusion: There is not consistency of results even in identical subjects research field. Many studies are ongoing to optimize combination between mechanical surface treatment and biomaterials such as extracellular matrix component and growth factors.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.29-37
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• 2011

Purpose: In cases when implant supported overdenture is made by using standard size implant, additional procedure such as bone surgery and bone grafting can be required. And it gives burden to doctor and patient in terms of cost. Therefore, it is necessary to find the implant therapy for the edentulous patients in making denture with accordable cost and simple procedure. Materials and methods: Edentulous patients with upper and lower dentures participated in this study. Before the operation, survey about patient's satisfaction to the existing dentures was carried out. Surgical procedures included four small diameter implants installation anterior area and immediate loading. One and three month after the procedure, the same survey about patient's satisfaction was carried out, and radiography was taken. Results: We are doing research to the nine patients. Survival rate is 97.2 percent. The comparison of patient's satisfaction before and after surgery is performed based on oral health impact profile 49. We analyze mainly with masticatory discomfort, retention, aesthetics, social problem, psychological discomfort problems. As a result, satisfaction level is increased at all factors. Retention is the most increased satisfactory factor followed by mastication difficulty, pronunciation, psychological discomfort, social discomfort, aesthetics in order. Marginal bone loss is 0.21 mm at 12 weeks after implant placement. Conclusion: This research reveals that the denture supported by mini dental implant increases patient's satisfaction. This study will be continued with more patients for a long time and we are scheduled for taking additional radiography to check whether peri-implant bone resorption occurs or not.