• Journal of Korean Neurosurgical Society
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• v.55 no.2
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• pp.73-77
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• 2014

Objective : The purpose of this study was to evaluate the efficacy of implant removal of percutaneous short segment fixation after vertebral fracture consolidation in terms of motion preservation. Methods : Between May 2007 and January 2011, 44 patients underwent percutaneous short segment screw fixation due to a thoracolumbar burst fracture. Sixteen of these patients, who underwent implant removal 12 months after screw fixation, were enrolled in this study. Motor power was intact in all patients, despite significant vertebral height loss and canal compromise. The patients were divided into two groups by degree of osteoporosis : Group A (n=8), the non-osteoporotic group, and Group B (n=8), the osteoporotic group. Imaging and clinical findings including vertebral height loss, kyphotic angle, range of motion (ROM), and complications were analyzed. Results : Significant pain relief was achieved in both groups at final follow-up versus preoperative values. In terms of vertebral height loss, both groups showed significant improvement at 12 months after screw fixation and restored vertebral height was maintained to final follow-up in spite of some correction loss. ROM (measured using Cobb's method) in flexion and extension in Group A was $10.5^{\circ}$ ($19.5/9.0^{\circ}$) at last follow-up, and in Group B was $10.2^{\circ}$ ($18.8/8.6^{\circ}$) at last follow-up. Both groups showed marked improvement in ROM as compared with the screw fixation state, which was considered motionless. Conclusion : Removal of percutaneous implants after vertebral fracture consolidation can be an effective treatment to preserve motion regardless of osteoporosis for thoracolumbar burst fractures.

• 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.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.494-503
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• 2016

PURPOSE. The aim of this study was to compare the efficacies of two-implant splinting (2-IS) and single-implant restoration (1-IR) in the first and second molar regions over a mean functional loading period (FLP) of 40 months, and to propose the appropriate clinical considerations for the splinting technique. MATERIALS AND METHODS. The following clinical factors were examined in the 1-IR and 2-IS groups based on the total hospital records of the patients: sex, mean age, implant location, FLP, bone grafting, clinical crown-implant ratio, crown height space, and horizontal distance. The mechanical complications [i.e., screw loosening (SL), screw fracture, crown fracture, and repeated SL] and biological complications [i.e., peri-implant mucositis (PM) and peri-implantitis (PI)] were also evaluated for each patient. In analysis of two groups, the chi-square test and Student's t-test were used to identify the relationship between clinical factors and complication rates. The optimal cutoff value for the FLP based on complications was evaluated using receiver operating characteristics analysis. RESULTS. In total, 234 patients with 408 implants that had been placed during 2005 - 2014 were investigated. The incident rates of SL (P<.001), PM (P=.002), and PI (P=.046) differed significantly between the 1-IR and 2-IS groups. The FLP was the only meaningful clinical factor for mechanical and biological complication rates in 2-IS. CONCLUSION. The mechanical complication rates were lower for 2-IS than for 1-IR, while the biological complication rates were higher for 2-IS. FLP of 39.80 and 46.57 months were the reference follow-up periods for preventing biological and mechanical complications, respectively.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.4
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• pp.329-340
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• 2006

Statement of problem: Damping of the peak force transmitted to implants has been reported by in vitro studies using impact forces on resin-veneered superstructures. Theoretical assumptions suggest that use of acrylic resin for the occlusal surfaces of a prosthesis would protect the connection between implant and bone. Therefore, the relationship between prosthesis materials and the force transmitted through the implant system also needs to be investigated under conditions that resemble the intraoral mechanical environment. Purpose: The purpose of this study was to analyze the fracture strength and modes of temporary prosthesis when a flange or occlusally extended structure were connected on the top of the abutment. Material and method: Modified abutments of winged and bulk design were made by casting the desired wax pattern which is made on the UCLA type plastic cylinder. Temporary crowns were made using templates on the modified abutments, and its fracture toughness and strain were compared to the traditional temporary prosthesis. To evaluate the effect of aging, 5.000 times of thermocycling were performed, and their result was compared to the 24hours specimen result. Results: The following conclusions were drawn from this study: 1. In the fracture toughness test, temporary crown's fracture line located next to the screw hole while modified designs with metal support showed fracture line on the metal and its propagation along the metal-resin interface. 2. Wing and bulk structure didn't show significant difference in the fracture toughness (p>0.05), but wing structure showed stress concentration on the screw hole area compared to bulk structure which showed even stress distribution. 3. In the fracture toughness test after thermocycling, wing and bulk structure showed increased or similar results in metal supported area while off-metal area and temporary crown showed decreased results. 4. In the strain measurement after thermocycling, its value increased in the temporary and bulk structure. However, wing structure showed decreased value in the loading point while increased value in the screw hole area. Conclusion: Wing type design showed compatible result to the bulk type that its application with composite resin prosthesis to the implant dentistry is considered promising.

• The Journal of the Korean dental association
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• v.49 no.7
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• pp.389-397
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• 2011

Bisphosphonate inhibits the function of osteoclast, so they are widely used for multiple myeloma, Paget's disease, metastatic malignant bone disease, and severe osteoporosis. This drug is very effective for preventing severe complication of osteoporosis, some unpredictable complication occurred such as esophageal malignancy, atypical fracture of femur, and osteonecrosis of the jaw. Bisphosphonate related osteonecrosis of the jaw (BRONJ) is closely related with invasive, open bone surgery like tooth extraction. BRONJ associated with dental implant is rare, however, as the use of bisphosphonate increase, BRONJ cases with dental implant are increasing. In this article, we will describe the considerations during dental implant treatment for patient under bisphosphonate therapy.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.209-216
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• 2004

The purpose of this study is to introduce how to make implant supported over denture with Oring. Many kinds of attachments have used to dental restorations. The application of attachment has widely increased implant fixed prosthesis and implant supported over denture. In order that implant supported over denture have properly retention, generally used O-ring, magnetic, bar attachment. O-ring give us an advantage that is required more minimum vertical dimension than bar-type and easily replace with new part. When we make these prosthesis using O-ring, Bar, Ball attachment, we should following procedures. Strong occlusion force leads to fracture of over denture because part of functional mechanism as implant abutment or attachment is spaced. Clips are regularly activated. O-ring and springs are changed every year. The pattern of resorption should be carefully monitored and compensated for by relining procedures. If the over denture appears to rest on the bar or the ball attachments, relining should be performed and clips/caps should be changed.

• The Journal of the Korean dental association
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• v.54 no.3
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• pp.198-205
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• 2016

The purpose of this paper was to investigate the significance of splinted and non-splinted implant-supported restorations with an internal connection for multiple consecutively missing teeth. Upon examination of the effects of fixture-abutment connection, the distribution of occlusal load was favorable in splinted implant-prosthesis with an external connection, but effect of strain distribution was not significant in splinted implant-prosthesis with an internal connection. In splinted implant-prostheses for short implants, strain distribution was not affected by the method of retention. For cement-retained prostheses, the effect of strain distribution due to splinting was not significant. In clinical studies, non-splinted prostheses with an internal connection for multiple consecutively missing teeth showed high survival rate, mild marginal bone loss, and stable periodontal condition. However, failure to achieve optimal proximal contact between single-unit prostheses may lead to food impaction, and veneer fracture may be inevitable when the framework provides inadequate support in the proximal region. In conclusion, splinted implant-prosthesis is not an indication in all cases, and clinical consideration of its use should be based on the patient's oral condition, such as location and number of implants, formation of proximal contact, canine guidance, existence of parafunctional habit, and oral hygiene, when multiple consecutively missing teeth are replaced by internal connection type implant.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.239-245
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• 2016

Purpose: The purpose of this study was to identify clinical complications in removable partial denture (RPD) with implant-supported surveyed prostheses, and to analyze the factors associated with the complications such as location of the implant, splinting adjacent prostheses, the type of retentive clasps, Kennedy classification, and opposing dentition. Materials and Methods: A retrospective clinical study was carried out for 11 patients (7 male, 4 female), mean age of 67.5, who received RPD with Implant-supported surveyed prostheses between 2000 and 2016. The mechanical complications of 11 RPDs and 37 supporting implant prostheses and the state of natural teeth and peripheral soft tissue were examined. Then the factors associated with the complications were analyzed. Results: The average of 3.4 implant-supported prostheses were used for each RPD. Complications found during the follow-up period of an average of 42.1 months were in order of dislodgement of temporary cement-retained prostheses, opposing tooth fracture/mobility, screw fracture/loosening, clasp loosening, veneer porcelain fracture, marginal bone resorption and mobility of implant, artificial tooth fracture. Complications occurred more frequently in anterior region compared to posterior region, non-splinted prostheses compared to splinted prostheses, surveyed prostheses applied by wrought wire clasp compared to other clasps, and natural dentition compared to other removable prostheses as opposing dentition. There were no significant differences in complications according to the Kennedy classification. Conclusion: All implant-assisted RPD functioned successfully throughout the follow-up. However, further clinical studies are necessary because the clinical evidences are still not enough to guarantee the satisfactory prognosis of implant-assisted RPD for long-term result.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.23 no.1
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• pp.34-40
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• 2014

There are several treatment options for rehabilitation of partial edentulism including the use of conventional or implant-retained fixed prostheses. However, such prosthetic options cannot always be possible because of compromised general and oral health (i.e. loss of supporting tissues, medical reasons, extensive surgical protocol and osseointegration failure of dental implant) as well as the affordability of patients. In some cases, removable partial denture provides easier access for oral hygiene procedures and the ability to correct discrepancies in dental arch relationships than implant fixed prosthesis. Recently, Implant Supported Removable Partial Denture (ISRPD) where to place dental implant in strategic position has been suggested to improve the limitation and shortcomings of conventional RPD. ISPRD can overcome mechanical limition of conventional RPD by placing implant in a favorable position and can be cost-effective, prosthetic solution for partially edentulous patients who are not immediate candidates for extensive, fixed implant supported restorations. Incorporation of dental implants to improve the RPD support and retention and to enhance patient acceptance should be considered when treatment planning for RPD. In this case, 59 years old male patient who received dental treatment of implant fixed prosthesis on both side of the upper jaw and implant overdenture on lower jaw showed implant abutment screw fracture on #15i and osseointegration failure on multiple number of implants. After removing failed implants, we planned ISRPD using #15i,24i,25i,26i and #23 natural tooth for RPD abutment. We fabricated #23 surveyed crown,#24i=25i=26i surveyed bridge and #15i gold coping for support,retention and stability for RPD. Periodic follow up check for 2years has been performed since the ISRPD delivery to the patient. No sign of screw loosening, fracture or bone resorption around abutment implants were detected.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.2
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• pp.121-143
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• 2010

To investigate the effect of implant types and bone resorption on the fracture characteristics. 4 types of Osstem$^{(R)}$Implant were chosen and classified into external parallel, internal parallel, external taper, internal taper groups. Finite elements analysis was conducted with ANSYS Multi Physics software. Fatigue fracture test was performed by connecting the mold to the dynamic load fatigue testing machine with maximum load of 600N and minimum load of 60N. The entire fatigue test was performed with frequency of 14Hz and fractured specimens were observed with Hitachi S-3000 H scanning electron microscope. The results were as follows: 1. In the fatigue test of 2 mm exposed implants group, Tapered type and external connected type had higher fatigue life. 2. In the fatigue test of 4 mm exposed implants group, Parallel type and external connected types had higher fatigue life. 3. The fracture patterns of all 4 mm exposed implant system appeared transversely near the dead space of the fixture. With a exposing level of 2 mm, all internally connected implant systems were fractured transversely at the platform of fixture facing the abutment. but externally connected ones were fractured at the fillet of abutment body and hexa of fixture or near the dead space of the fixture. 4. Many fatigue striations were observed near the crack initiation and propagation sites. The cleavage with facet or dimple fractures appeared at the final fracture sites. 5. Effective stress of buccal site with compressive stress is higher than that of lingual site with tensile stress, and effective stress acting on the fixture is higher than that of the abutment screw. Also, maximum effective stress acting on the parallel type fixtures is higher. It is careful to use the internal type implant system in posterior area.