• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.280-289
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• 2008

STATEMENT OF THE PROBLEM: Recent data regarding the effects the cement type and abutment heights on the retentive force of a prosthetic crown are inconsistent and unable to suggest clinical guidelines. PURPOSE OF THE STUDY: This study evaluated the effects of different types of temporary cements and abutment heights on the retentive strength of cement-retained implant-supported prostheses. MATERIALS AND METHODS: Prefabricated implant abutments, 4 mm in diameter, $8^{\circ}$taper per side, and light chamfer margins, were used. The abutment heights of the implants were 4 mm, 5.5 mm and 7 mm. Seven specimens of a single crown similar to a first premolar were fabricated. Six commercially available temporary cements, TempBond, TempBond NE, Cavitec, Procem, Dycal, and IRM, were used in this study. Twenty-four hours after cementation, the retentive strengths were measured using a universal testing machine with a crosshead speed of 0.5 mm/min. The cementation procedures were repeated 3 times. The data was analyzed using two-way analysis of variance and a Tukey test (${\alpha}$=0.05). RESULTS: The tensile bond strength ranged from 1.76 kg to 19.98 kg. The lowest tensile strengths were similar in the TempBond and Cavitec agents. Dycal showed the highest tensile bond strength (P<0.01). More force was required to remove the crowns cemented to the long abutments (P<0.05). CONCLUSION: TempBond and Cavitec agents showed the lowest mean tensile bond strength. The Dycal agent showed more than double the tensile bond strength of the TempBond agent.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.177-193
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• 2004

Several experimental studies showed that the application of small amounts of electric current to bone stimulated osteogenesis at the site of the cathode and suggested that electrical currents promote osseointegration around dental implants. The purpose of this study was to determine the effect of direct microcurrent to endosseous titanium implants placed in bone defects. The right and left 2nd, 3rd and 4th mandibular premolars in ten mongrel dogs (15Kg of weight) were extracted. One monthe later, Ti-machined screw type implants(3.8 mm diameter x 8.5 mm length, $AVANA^{(R)}$, Ostem) were placed in surgically created circumferential defect area(width 5mm, depth 4mm). The implants were divided into three groups according to the treatment modalities: Control group- implants without electrical stimulation; Experimental group I- implants with allogenic demineralized freeze dried bone grafting; and Experimental group II-implants allogenic demineralized freeze dried bone grafting and electric stimulation. The animals were sacrificed in the 4th and 8th week after implant placement and un-decalcified specimens were prepared for histological and histometrical evaluation of bone-implant contact ratio (BIC) and bone formation area ratio (BFA) in defect area. Some specimens at 8 weeks after implantation were used for removal torque testing. Histologically, there was connective tissue infiltration in the coronal part of defect area in control and the experimental group I, whereas direct bone contact was found in the experimental group II without connective tissue invasion. Average BIC ratios at 4 weeks of healing were 60.1% in the experimental group II, 47.4% in the experimental group I and 42.7% in the control. Average BIC ratios at 8 weeks after implantation were 67.6% in the experimental group II, 55.9% in the experimental group I and 54.6% in the control. The average BFA ratio was 84.0% in the experimental group II, 71.8% in the experimental group I and 58.8% in the control at 4 weeks, and the BFA ratios were 89.6% in the experimental group II, 81.4% in the experimental group I and 70.5% in the control at 8 weeks after implantation. The experimental group II showed also significantly greater BIC and BFA ratios compared to the control and the experimental group I (p<0.05). The removal torque values at 8 weeks after implantation were 56 Ncm in the experimental group II, 49 Ncm in the experimental group I and 43 Ncm in the control. There was a statistically significant difference among 3 groups (p<0.05). These results suggest that electrical stimulation improve and accelerate bone healing around endosseous titanium implants in bone defect.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.349-360
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• 2009

Purpose: As the esthetic demands of dental implant patients are increased, the demands of zirconia as implant abutment material are also increased. It has non-metalic color, good biocompatibility, high strength and high toughness. Even thought the advatage of zirconia abutment, there are a few studies about mechanical properties of zirconia abutment. This study evaluated the mecanical strength with compressive bending strength and endurance limit of implant-zirconia abutment assembly. Materials and Methods: Static and cyclic loading of implant-Zirconia abutment assembly were simulated under worst case condition according to ISO. Test groups were implants of external butt joint with straight regular diameter and angled regular diameter zirconia abutment, implant of external butt joint with narrow straight diameter zirconia abutment and implant of internal conical joint with straight narrow diameter zirconia abutment. All test group were evaluated the mecanical strength with compressive bending strength and endurance limit. After fatique testing, fracture surface were examined by SEM. Results: The compressive bending strengths exceed 927N. Regular diameter zirconia abutment were stronger than narrow diameter zirconia abutment(P<.05). The endurance limits ranged from 503N to 868N. Conclusion: Within the limitation of this study, zirconia implant abutment exceeded the estabilished values for maximum incisal biting forces reported in the literature.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.64-71
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• 2024

Purpose: The purpose of this study is to evaluate Ti-base abutment's three different heights and three different cement types on the pull-off force of zirconia-based restorations. Materials and Methods: A total of 90 fixture lab analogs were embedded in auto polymerizing resin bloack. 90 Ti-base abutments heights of 3 mm, 5 mm, 7 mm were scanned and zirconia restoration were prepared from scanned files. Zirconia restoration were cemented with three different types of cements (temporary, semi-permanent, permanent) following manufacturer's instructions. All 90 specimens were placed and tested in a universal testing machine for pull-out testing. Retention was measured by recording the force at load drop. Statistical analysis was performed using Kruskal-Wallis test for detecting whether there are any statistical significance along cement types or abutment heights. After that, Mann-Whitney test was used for figuring out differences regarding abutment height and the comparison between 3 cements. Results: Temp bond showed significantly lower pull-off force compared to Fujicem regardless of any abutment height. However, there were significant differences between Cem-implant and Fujicem in abutment height of 3 mm and 7 mm, but there was no significant difference in 5 mm. Temp bond and Cem-implant had significant differences only in abutment height of 5 mm. Conclusion: Although Ti-base abutment height did not influenced zirconia restorations' retentiveness, cement types showed significant differences.

• The Journal of the Korean dental association
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• v.49 no.3
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• pp.159-169
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• 2011

The author have been conducting research on the development of biomaterials using human teeth since 1993, and we recently reported the results of several of our advanced studies. Based on previous studies, new bone graft material using autogenous tooth(AutoBT) was developed. The author performed implant placement combined with GBR and sinus bone graft using AutoBT during the period of June 2009 to September 2009. During the postsurgical healing period, clinical and radiological evaluations were performed. For patients who consented to histological testing, tissue samples were obtained and histological examination was performed two months and four months after GBR and four months after sinus bone graft. Serious complications pertinent to bone graft materials were not observed, and it was shown that the level of the crestal bone in the vicinity of implants was relatively well maintained. In histologic examination after two months and four months, favorable new bone formation was observed.

• Journal of dental hygiene science
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• v.16 no.1
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• pp.93-100
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• 2016

The purpose of this study was to compare the changes of retentive force in different stud attachment systems for implant retained overdenture. Two commercially available attachments with different retentive forces were investigated: Kerator (pink, blue, red) and O-ring (orange, red). Two implant fixtures were vertically embedded in base mountings. Five pairs of each attachment were evaluated. A universal testing machine was used to evaluate the retentive force of two attachments during wear simulation. Surface characteristics of each attachment system were evaluated with scanning electron microscopy. Five pairs of each attachment were evaluated. Kerator pink showed the highest initial retention. After 2,500 cycles of wear-simulation, Kerator pink noted the largest decrease in retention. According to results of surface analysis, Worn surfaces were obtained in matrices and patrices. Heavy wears were observed in matrices. After 2 year-wear simulation, most attachments exhibited retention loss. Attachments using different kind of material exhibited dissimilar surface alterations.

• The korean journal of orthodontics
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• v.41 no.4
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• pp.268-279
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• 2011

Objective: The purpose of this study was to compare self-drilling orthodontic mini-implants of different surfaces, namely, machined (untreated), etched (acid-etched), RBM (treated with resorbable blasting media) and hybrid (RBM + machined), with respect to the following criteria: physical appearance of the surface, measurement of surface roughness, and insertion pattern. Methods: Self-drilling orthodontic mini-implants (Osstem implant, Seoul, Korea) with the abovementioned surfaces were obtained. Surface roughness was measured by using a scanning electron microscope and surface-roughness-testing machine, and torque patterns and vertical loadings were measured during continuous insertion of mini-implants into artificial bone (polyurethane foam) by using a torque tester of the driving-motor type (speed, 12 rpm). Results: The mini-implants with the RBM, hybrid, and acid-etched surfaces had slightly increased maximum insertion torque at the final stage ($p$ < 0.05). Implants with the RBM surface had the highest vertical load for insertion ($p$ < 0.05). Testing for surface roughness revealed that the implants with the RBM and hybrid surfaces had higher Ra values than the others ($p$ < 0.05). Scanning electron microscopy showed that the implants with the RBM surface had the roughest surface. Conclusions: Surface-treated, self-drilling orthodontic mini-implants may be clinically acceptable, if controlled appropriately.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.13.1-13.7
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• 2015

Background: This study evaluated Somatosensory evoked potentials (SEP), Quantitative sensory testing (QST), and thermography as diagnostic methods for nerve injury. Methods: From 2006 through 2011, 17 patients (mean age: 50.1 years) from ${\bigcirc}{\bigcirc}{\bigcirc}{\bigcirc}$ Hospital who sought care for altered sensation after dental implant treatment were identified. The mean time of objective assessment was 15.2 months after onset. Results: SEP of Inferior alveolar nerve(IAN) was $15.87{\pm}0.87ms$ on the normal side and $16.18{\pm}0.73ms$ on the abnormal side. There was delayed N20 latency on the abnormal side, but the difference was not statistically significant. In QST, the abnormal side showed significantly higher scores of the current perception threshold at 2 KHz, 250 Hz, and 5 Hz. The absolute temperature difference was $0.55^{\circ}C$ without statistically significance. Conclusion: These results indicate that QST is valuable as an objective method for assessment of nerve injury.

• Korean Journal of Veterinary Research
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• v.50 no.4
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• pp.311-317
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• 2010

Recently the micropig has been developed as human disease model. The dental and orofacial region of micropig is similar to that of humans, so it has been used for testing implant materials and techniques. The purpose of this study is on dental image at each age using radiography and computed tomography. Total twenty-two male micropigs, two or three animals of each 1, 3, 5, 7, 9, 12, 18 and 24 months old, were given radiographic examinations. After general anesthesia, extra- and intra-oral radiographic technique and computed tomographic scans were performed to assess the dental characterization of micropigs. The total deciduous dental formula comprised 28 teeth and was depicted as Di 3/3, Dc 1/1, Dp 3/3. The total permanent dental formula comprised 44 teeth and was depicted as I 3/3, C 1/1, P 4/4, M 3/3. Hypodontia of the first premolars was common in the micropig. The permanent teeth erupted from 3 to 24 month after birth. The sequence of eruption of the permanent teeth was M1, P1, I3, C, M2, I1 + P3 + P4, P2, I2, M3. Dental imaging enables visualization of the unerupted teeth and gives more information about the development of the teeth. The growth pattern of the teeth obtained through radiographic and computed tomographic examination provides basic data in the micropig as animal model for dental research.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.677-692
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• 1998

In order to study the effects of cigarette smoking on periodontal tissue, gingival fibroblast from the smoking and nonsmoking groups were cultured and each group were treated with nicotine(50ng/ml,100ng/ml) and NNK(50ng/ml, 100ng/ml) to test their attachment ability at time intervals of 30minutes, 60minutes, 90minutes, 120minutes, and 240minutes. Using the same method, the growth each group treated with nicotine and NNK in order to compare their attachment ability and growth rate was done. The Results are as follows. 1. In comparing the attachment ability and growth rate between the smoking and non-smoking group were significantly higher in all time intervals. 2. When the attachment ability was com-pared among these two groups after treatment with nicotine and NNK, the non-smoking group showed decrease in attachment ability while the smoking group was not affected. 3. The growth rate of these two groups were compared after treating with nicotine and NNK. The growth rate of fibroblast from the non-smoking group decreased while fibroblast from the smoking group was not affected. These results suggest that fibroblast from the non-smoking group showed higher attachment ability, growth rate, and sensitivity to nicotine and NNK. This implies that fibroblast from the non-smoking group is a more reliable source in testing the cytotoxicity of nicotine and NNK. Also it could be reasonable to think that nicotine and NNK is a probable cause for problems in attachment and repair mechanism.