• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.255-268
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• 2004

The purpose of the research is to compare the distribution of Black-pigmented Bacteroides between Chronic Periodontitis and Aggressive Periodontitis. P. gingivalis, P. intermedia and P. nigrescens were examined in order to evaluate their distribution in patients with Chronic Periodontitis(CP) and Aggressive Periodontitis(AP). PCR and dot-blots hybridization of 16s rRNA gene were used to compare bacterial distribution of two groups - CP group and AP group, which were divided into two subgroups. Subgingival plaque taken from the diseased sites(pocket $depth{\geq}6$ mm) and healthy sites(pocket $depth{\leq}3$ mm) were grouped into the experimental group and the control group. The result are as follows ; 1. The distribution of P. gingivalis was 98.33% for chronic Periodotitis(CP), 94.17% for Aggressive Periodontitis(AP), the distribution of P. intermedia was 77.50% for CP, 64.17% for AP, and the distribution of P. nigrescens was 35.00%, 29.17%. In all 3 types of bacteria, CP group showed higher distribution compared to AP group, but only P. intermedia showed statistically significant difference. 2. In the case of CP, every type of bacteria showed higher distribution in the experimental group with statistically significant difference. 3. In the case of AP, every type of bacteria also showed higher distribution in the experimental group, but P. gingivalis and p..intermedia showed the result with statistically significant difference, and the other did not 4. In 3 all bacteria type, N-AP showed higher distribution than N-CP without statistically significant difference These results suggest that the comparison of the distribution of Bacteroides between Chronic Periodontitis and Aggressive Periodontitis has no statistically significant difference, except P. intermedia.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.1
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• pp.69-78
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• 2007

This study was performed to compare the stress distribution pattern in the crestal cortical bone and cancellous bone using 3-dimensional finite element stress analysis when 2 different Young's modulus(high modulus, model 1; low modulus, model 2) of cancellous bone was assumed. For the analysis, a finite element model was designed to have two square-threaded implants fused together and located at first and second molar area. Stress distribution was observed when vertical load of 200N was applied at several points on the occlusal surfaces of the implants, including central fossa, points 1.5mm, 2mm, 3mm and 3.5mm buccally away from central fossa. The results were as follows; 1. In both model, the maximum Von-Mises stress in the crestal cortical bone was greater when the load was applied at the central point, points 1.5mm and 2mm buccally away from central fossa than other cases. 2. In the cortical bone around first and second molar, model 2 showed greater Von-Mises stress than model 1. It is concluded that when the occlusal contact is afforded, the distribution of stress varies depending on the density of cancellous bone and the location of loading. More favorable stress distribution is expected when the contact load is applied within the diameter of fixtures.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.3
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• pp.186-195
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• 2018

Purpose: We performed quantitative and qualitative analysis of typical periodontal bacteria using real time PCR method to investigate the microbiological difference according to the severity of peri-implant disease in Koreans. Materials and Methods: Total of 60 implants were divided into three groups (healthy group, peri-implant mucositis group, peri-implantitis group) through periapical radiographs and clinical indices. The evaluated clinical parameters were pocket depth, plaque index, suppuration and bleeding on probing. Using a sterilized curette instrument, microbial samples were collected from the subgingival plaque and real-time PCR was performed on five periodontal bacteria. The relative expression levels of microorganisms were compared by comparative delta-CT method. Results: The relative expression levels of E. corrodens and T. denticola were significantly higher in the peri-implantitis group (P < 0.017). On the other hand, the relative expression level of F. nucleatum and P. gingivalis was relatively high in the healthy implant group regardless of the severity of disease. P. intermedia was significantly lower in the healthy implant group (P < 0.017). Conclusion: Periodontal bacteria were detected in Koreans with peri-implant diseases, but there was no microbiological distribution similar to periodontitis.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.4
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• pp.249-256
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• 2022

The implant prosthesis of anterior maxilla requires careful consideration in planning. In order to satisfy both esthetic and functional needs of a patient, fusion of intra-oral scan in Cone-beam computed tomography (CBCT) and facial scan can be considered. Bony structures and soft tissues captured in CBCT and occlusal surfaces of intra oral scan were incorporated into personal characteristics from facial scan. The patient had insufficient buccal bone on maxillary anterior area. The maxillary implants could not be placed on the most ideal position. However, the "top down" approach completed by computer-generated arranging of teeth in implant planning and surgery with surgical guide resulted in esthetically and functionally satisfying result regardless of the limitation. Careful diagnosis with digital technique and the usage of surgical guide resulted in successful surgery and esthetic restoration. The temporary fixed prostheses were designed, restored and evaluated. The patient was not satisfied with the first design of temporary prosthesis, which showed uneven space distribution between teeth due to the position of maxillary implant. The design was modified by changing proximal emergence contours and line angle to alter the perceived since of incisors. The patient was satisfied with the new design of provisional restoration. A digital occlusion analyzer (Arcus Digma II, KaVo, Leutkirch, Germany) was used to measure inherent condylar guidance and anterior guidance of a patient to provide a definitive prosthesis.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.259-266
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• 2016

In edentulous mandible, implant supported overdenture was considered as a first treatment option. Konus type attachment supplies rigid support and cross arch stabilization so that more favorable force transmission and distribution can be attained. In the dentistry, computer aided design-computer aided manufacturing (CAD-CAM) system makes it possible to fabricate restorations with high precision and effectiveness. Recently, Palladium-silver (Pd-Ag) alloy which is millable has been developed. This article presents that application of CAD-CAM Konus type attachment can be provide satisfactory stability and function on four-implant supported mandibular overdenture.

• Journal of Applied Reliability
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• v.17 no.1
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• pp.50-57
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• 2017

Purpose : This paper is a comparative analysis results of the fatigue test for dental implants and accelerated life test by using a static type loading device commonly used in Korea and a dynamic type loading device (universal-joint) recommended by FDA. Methods : Fatigue tests of dental implant is based on ISO 14801 and classified into static load test and dynamic load test. The tests were carried out on three test specimens by four load stress steps under each loading device. For analysis on failure mode such as crack, fracture and permanent deformation of test specimens, we used X-ray three-dimensional computed tomography on test specimens before and after the fatigue tests. The design of the accelerated life test was based on the analysis results of the fatigue life data obtained from the dynamic load test and the statistical analysis software (Minitab ver.15) was used to analyze the appropriate life distribution. Results : As a result of the fatigue tests and the accelerated life tests at same acceleration condition under each test method, the fatigue life under the dynamic type loading device (universal-joint) was shorter than when static type loading device was applied. Conclusion : This paper can be used as a reference when the universal-joint type loading device for implants fatigue test is applied as ISO 14801.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.1
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• pp.37-53
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• 2006

Purpose: The purpose of this study was to investigate the influences of the jaw dimension on the bone stress. Materials and Methods: Root analogue implant of Frialit-2 Synchro model in the jaw bone of various thickness from 8mm to 13mm were modelled axisymmetrically for a series of finite element analyses. As load conditions, non-axisymmetric lateral load of 20N and an oblique load of 50N, as well as an axisymmetric vertical load of 50N were taken into consideration. Results: The cervical area of implant under the axisymmetric load and the base cortical bone under the non axisymmetric load condition were the areas of main concern where the higher level of stress were likely to be obtained. Conclusion: The results indicated that at the two concerned areas drastically different stress distribution could take place as a function of the load conditions. Under the vertical load, the lower level of stress was observed for the narrow jaw bone at the cervical cortical bone whereas stress at the base cortical bone remained virtually unchanged. Under the non axisymmetric load condition, however, the stress at the base cortical bone increased very rapidly as the jaw bone width increased without inducing any significant change in the stress level at the cervical area.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.127-140
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• 2013

The Locator attachment is used widely for implant retained overdenture. It can be used solitary and needs small vertical space. Locator can be applicable for parallel implants and divergent implants. Nylon male cap allow personalized retention for each case. In this literature review, initial retention force and changes in retention force of various attachments were evaluated. Rotation freedom and stress distribution around the attachment were reviewed. Moreover, patient satisfaction and maintenance care of Locator attachment were described. From all of the researches, it was drawn that Locator attachment can be used successfully and widely in several clinical situations.

• The Journal of Advanced Prosthodontics
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• v.7 no.2
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• pp.160-165
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• 2015

PURPOSE. In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS. Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous$^{(R)}$; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at $30^{\circ}$ in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov-Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student's t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS. Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION. Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants.

• Korean Journal of Audiology
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• v.24 no.2
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• pp.71-78
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• 2020

Background and Objectives: Currently limited information is available on speech stimuli processing at the subcortical level in the recipients of cochlear implant (CI). Speech processing in the brainstem level is measured using speech-auditory brainstem response (S-ABR). The purpose of the present study was to measure the S-ABR components in the sound-field presentation in CI recipients, and compare with normal hearing (NH) children. Subjects and Methods: In this descriptive-analytical study, participants were divided in two groups: patients with CIs; and NH group. The CI group consisted of 20 prelingual hearing impairment children (mean age=8.90±0.79 years), with ipsilateral CIs (right side). The control group consisted of 20 healthy NH children, with comparable age and sex distribution. The S-ABR was evoked by the 40-ms synthesized /da/ syllable stimulus that was indicated in the sound-field presentation. Results: Sound-field S-ABR measured in the CI recipients indicated statistically significant delayed latencies, than in the NH group. In addition, these results demonstrated that the frequency following response peak amplitude was significantly higher in CI recipients, than in the NH counterparts (p<0.05). Finally, the neural phase locking were significantly lower in CI recipients (p<0.05). Conclusions: The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech process in CI recipients.