• Journal of Applied Reliability
• /
• v.16 no.2
• /
• pp.104-109
• /
• 2016

Purpose: The purpose of this study is to analyze fracture behavior and failure mechanism of porous titanium for dental implant fabricated by space holder process. Method: Three porous titanium specimens with a specific volume fraction of open pore were test by 3 point bending and compression stress condition, respectively. Fracture appearance was observed by scanning electron microscope and discussed in relation with oxygen content. Results: For compression-tested specimens, two specimen showed brittle failure, while the other one showed normal failure after deformation. High oxygen content was detected in the brittle-fractured specimen. Several micro-cracks initiated at the struts propagated down to the bottom of the specimen resulting in normal failure. Conclusion: Oxygen contamination during the fabrication process can leads brittle premature failure, and hence quality problem of the porous titanium for dental implant.

• Archives of Craniofacial Surgery
• /
• v.20 no.6
• /
• pp.347-353
• /
• 2019

Most orbital surgeons believe that it's difficult to restore the primary orbital wall to its previous position and that the orbital wall is so thin that cannot be firmly its primary position. Therefore, orbital wall fractures generally have been reconstructed by replacing the bony defect with a synthetic implant. Although synthetic implants have sufficient strength to maintain their shape and position in the orbital cavity, replacement surgery has some drawbacks due to the residual permanent implants. In previous studies, the author has reported an orbital wall restoring technique in which the primary orbital wall fragment was restored to its prior position through a combination of the transorbital and transantral approaches. Simple straight and curved elevators were introduced transnasally to restore the orbital wall and to maintain temporary extraorbital support in the maxillary and ethmoid sinus. A transconjunctival approach provided sufficient space for implant insertion, while the transnasal approach enabled restoration of the herniated soft tissue back into the orbit. Fracture defect was reduced by restoring the primary orbital wall fragment to its primary position, making it possible to use relatively small size implant, furthermore, extraorbital support from both sinuses decreased the incidence of implant displacement. The author could recreate a natural shape of the orbit with the patient's own orbital bone fragments with this dual approach and effectively restored the orbital volume and shape. This procedure has the advantages for retrieving the orbital contents and restoring the primary orbital wall to its prior position.

• The Journal of Korean Academy of Prosthodontics
• /
• v.45 no.3
• /
• pp.295-302
• /
• 2007

Statement of problem. Fracture of the tooth-colored superstructure material is one of the main prosthetic complications in implant-supported prostheses. Purpose. The purpose of this in vitro study was to compare the fracture strength between the cement-retained implant-supported metal-ceramic crowns and the indirect composite resinveneered metal crowns under the vertical compressive load. Material and methods. Standard implants of external type (AVANA IFR 415 Pre-mount; Osstem Co., Busan, Korea) were embedded in stainless steel blocks perpendicular to their long axis. Customized abutments were fabricated using plastic UCLA abutments (Esthetic plastic cylinder; Osstem Co., Busan, Korea). Thirty standardized copings were cast with non-precious metal (Rexillium III, Pentron, Walling ford, Conn., USA). Copings were divided into two groups of 15 specimens each (n = 15). For Group I specimens, metal-ceramic crowns were fabricated. For Group II specimens, composite resin-veneered (Sinfony, 3M-ESPE, St. Paul, MN, USA) metal crowns (Sinfony-veneered crowns) were fabricated according to manufacturer's instructions. All crowns were temporary cemented and vertically loaded with an Instron universal testing machine (Instron 3366, Instron Corp., Norwood, MA, USA). The maximum load value (N) at the moment of complete failure was recorded and all data were statistically analyzed by independent sample t-test at the significance level of 0.05. The modes of failure were also investigated with visual analysis. Results. The fracture strength of Sinfony-veneered crowns ($2292.7{\pm}576.0N$) was significantly greater than that of metal-ceramic crowns ($1150.6{\pm}268.2N$) (P < 0.05). With regard to the failure mode, Sinfony-veneered crowns exhibited adhesive failure, while metal-ceramic crowns tended to fracture in a manner that resulted in combined failure. Conclusion. Sinfony-veneered crowns demonstrated a significantly higher fracture strength than that of metal-ceramic crowns in cement-retained implant-supported prostheses.

• Journal of Korean Neurosurgical Society
• /
• v.51 no.4
• /
• pp.203-207
• /
• 2012

Objective: The purpose of this prospective study was to evaluate the efficacy and safety of screw fixation without bone fusion for unstable thoracolumbar and lumbar burst fracture. Methods: Nine patients younger than 40 years underwent screw fixation without bone fusion, following postural reduction using a soft roll at the involved vertebra, in cases of burst fracture. Their motor power was intact in spite of severe canal compromise. The surgical procedure included postural reduction for 3 days and screw fixations at one level above, one level below and at the fractured level itself. The patients underwent removal of implants 12 months after the initial operation, due to possibility of implant failure. Imaging and clinical findings, including canal encroachment, vertebral height, clinical outcome, and complications were analyzed. Results: Prior to surgery, the mean pain score (visual analogue scale) was 8.2, which decreased to 2.2 at 12 months after screw fixation. None of the patients complained of worsening of pain during 6 months after implant removal. All patients were graded as having excellent or good outcomes at 6 months after implant removal. The proportion of canal compromise at the fractured level improved from 55% to 35% at 12 months after surgery. The mean preoperative vertebral height loss was 45.3%, which improved to 20.6% at 6 months after implant removal. There were no neurological deficits related to neural injury. The improved vertebral height and canal compromise were maintained at 6 months after implant removal. Conclusion: Short segment pedicle screw fixation, including fractured level itself, without bone fusion following postural reduction can be an effective and safe operative technique in the management of selected young patients suffering from unstable burst fracture.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.33 no.2
• /
• pp.173-180
• /
• 2007

According to the increase in use of implants in clinical dentistry, new kinds of complications happen. Complications that can happen during implant placement are bleeding, nerve injury, jaw fracture, fenestration of maxillary sinus or nasal cavity, dehiscence, fenestration, injury of adjacent tooth. And complications that can happen after implant operation are infection, bleeding, hematoma, chronic sinusitis, peri-implantitis. Problems that are confronted during implant placement happen by inadequate preoperative treatment plan, inadequate consideration about individual anatomic difference, inadequate operation process and lack of experience of clinician. It is important that clinicians consider possible complications in advance and make a comprehensive treatment plan. We report the patient who was happened ramus fracture during block bone harvesting from ramus of severely atrophic mandible, the patient who came to emergency ward due to postoperative swelling and bleeding and the patient whose implant was migrated to maxillary sinus with a review of literature.

• The Journal of Advanced Prosthodontics
• /
• v.7 no.6
• /
• pp.423-430
• /
• 2015

PURPOSE. To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth $Ankylos^{(R)}$ implants. MATERIALS AND METHODS. This was a retrospective clinical study that analyzed 450 single $Ankylos^{(R)}$ implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position. RESULTS. The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all P<.05). CONCLUSION. The $Ankylos^{(R)}$ implant is suitable for single-tooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.

• Archives of Craniofacial Surgery
• /
• v.10 no.1
• /
• pp.29-32
• /
• 2009

Purpose: Alloplastic implants, such as $Silastic^{(R)}$, $Supramid^{(R)}$, Porous polyethylene, $Teflon^{(R)}$ have been used to prevent reherniation of orbital tissue and are known to be inert for many years, though complications are infrequently reported many years after their insertion. Complications associated with implants are infrequent, but infection, orbital hemorrhage, implant extrusion, motility restriction, migration of implant causing dacryocystitis, cystic formation have been described. The latter was known as a rare late complication of blow-out fracture repair. Methods: We report the case of a discovery of a intraorbital hemorrhagic cyst which developed after silicon implant insertion. This patient developed diplopia, unilateral proptosis, exophthalmos, vertical dystopia, ectropion 10 years after repair of blow-out fracture. In this case, orbital CT scan revealed intraorbital cyst surrounding the orbital implant. At surgery, a fibrous capsule surrounded the silicon implant and was filled with mucin pools. Results: Proptosis, diplopia, exophthalmos, ectropion, vertical dystopia were resolved after surgical removal of the cyst and implant. Conclusion: This case illustrate that it is important for us to be aware of the complication of cyst formation around the silicon implants.

• Archives of Plastic Surgery
• /
• v.35 no.5
• /
• pp.597-602
• /
• 2008

Purpose: Presently, silicone rubber is chosen most frequently for nasal augmentation. However, there is a possibility of extrusion with this material. Sometimes, noses are prone to be traumatized, and then silicone rubber has a possibility of deformity or deviation resulting in trauma. We experienced cases with complications and traumatic deformities after the augmentation rhinoplasty. Methods: A retrospective review was performed to determine the characteristics of the implanted nasal silicone prosthesis after trauma. The patients' data such as deviation of implant, shape of fracture, age and sex of the patient, time of treatment, operative methods were reviewed. From March 2001 to March 2008, this study was performed in 30 patients. The patients were 25 females and 5 males, from 24 to 60 years of age, with an average of 42. All patients had previous augmentation rhinoplasty with silicone implant. Results: All of the 30 patients were confirmed as deviation of silicone and nasal bone fractures in the facial bone CT scan. The most common cause of fracture was traffic accident. The classification of nasal trauma after augmentation was done by facial bone CT. Class I: Deviation of silicone without nasal bone fracture without extrusion(12 cases, 40%), Class II: Deviation of silicone without nasal bone fracture and with extrusion(4 cases, 13%), Class III: Deviation of silicone with nasal bone fracture and without extrusion(8 cases, 27%), Class IV: Deviation of silicone with nasal bone fracture and with extrusion(3 cases, 10%), Class V: Mild deviation of silicone with nasal bone fracture(3cases, 3%). Specially, the comminuted or trapezoid nasal fracture was confirmed in 11 cases(Class III, IV). Conclusion: The problems of silicone implant have generally been related to foreign body reactions, rigidity of the material, encapsulation, infections, and extrusion. We experienced 11 cases of comminuted or comminuted trapezoid shaped fracture below nasal implant. So, we think this phenomenon could be used in late problem of silicone implant.

• Imaging Science in Dentistry
• /
• v.51 no.3
• /
• pp.251-260
• /
• 2021

Purpose: Dental implants are widely used for the rehabilitation of edentulous sites. This study investigated the occurrence of dental implant malpositioning as shown on post-implantation cone-beam computed tomography (CBCT) and to identify related factors. Materials and Methods: Samples with at least 1 malpositioned dental implant were collected from a central radiology clinic in Tehran, Iran from January 2017 to January 2019. Variables such as demographic characteristics, length and diameter of implants, type of implant, sites of implant insertion, different types of implant malpositioning problems (cortical plate perforation, interference with anatomical structures), angulation of the implant, and the severity of malpositioning were assessed. In addition, the incidence of implant fracture and over-drilling was evaluated. Data were statistically analyzed using the chi-square test, 1-sample t-test, and Spearman correlation coefficients. Results: In total, 252 patients referred for implant postoperative CBCT evaluations were assessed. The cases of implant malpositioning included perforation of the buccal cortical plate (19.4%), perforation of the lingual cortical plate (14.3%), implant proximity to an adjacent implant (19.0%), implant proximity to an adjacent tooth (3.2%), interference with anatomical structures(maxillary sinus: 18.3%, mandibular canal: 11.1%, nasal cavity: 6.3%, mental foramen: 5.6%, and incisive canal: 0.4%). Implant fracture and over-drilling were found in 1.6% and 0.8% of cases, respectively. Severity was categorized as mild (9.5%), moderate (35.7%), severe (37.7%), and extreme (17.1%), and 52.4% of implants had inappropriate angulation. Conclusion: CBCT imaging is recommended for detecting dental implant malpositioning. The most common and severe type of malpositioning was buccal cortex perforation.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.3
• /
• pp.425-432
• /
• 2012

This paper investigates shape design processes of two implant systems for bone fracture treatment ; Bone plate and Interlocking nail system. These systems can directly fix fractured human bones by surgical operations. The bone plates consist of various shaped plates and implant screws for fixation of fractured human bones with various manual instruments allowing to handle them. The material corresponds to titanium alloy Ti6Al4V because it is harmless material for human body as well as significantly rigid. This system has to be suitably rigid as well as manually bended in orthopedic surgery operations. The Interlocking nail system is a kind of nail implanted inside fractured human bones. The shapes of these systems have to be suitably designed in order to endure various loads as well as avoid any damages. If various shaped prototypes would be fabricated and tested to design the optimal shapes, optimal shapes could be obtained but very long time and expensive costs must be required. In this paper finite element method was applied into these systems. Under various boundary conditions a series of structural analysis was conducted by using ANSYS. Finally important shape factors could be determined on the basis of the analysis results.