Su-Young Lee

Comparison of two different PCR amplification products (the 18-kDa protein gene vs. RLEP repetitive sequence) in the diagnosis of Mycobacterium leprae.

Summary To determine the best molecular method for diagnosing leprosy, two sets of Mycobacterium leprae‐specific primers were compared. Fresh biopsies and slit skin smear samples were obtained from 67 leprosy patients and examined by touchdown (TD) PCR using primers amplifying either a 129‐bp fragment of the RLEP repetitive sequence or a 360‐bp fragment of the 18‐kDa protein gene of M.u2003leprae. Seventeen of 30 (56.7%) biopsy specimens and four of 37 (10.8%) slit skin smear specimens were positive using the primer for the 18‐kDa protein gene, whereas 24 of 30 (80%) biopsy and 27 of 37 (73%) slit skin smear samples showed detectable PCR products in the RLEP repetitive sequence. Twenty‐one of 31 cases (67.7%) with a bacterial index of zero were PCR positive for the primer RLEP repetitive sequence. These results demonstrate that detection of M.u2003leprae using PCR with primers to a RLEP sequence is more sensitive and specific than PCR with the 18‐kDa protein gene primers and also slit smears with acid fast staining. PCR of RLEP repetitive sequences is therefore a useful means of detecting M.u2003leprae DNA even when it is present at very low levels.

The effect of abutment screw length on screw loosening in dental implants with external abutment connections after thermocycling

PURPOSEnThe aim of this study was to investigate the effects of abutment screw length on screw loosening after thermocycling.nnnMATERIALS AND METHODSnTwenty-one grade 5 titanium (Ti) abutments were connected to grade 4 Ti implants with grade 5 Ti abutment screws. These implant/abutment screw/abutment assemblies were divided into seven groups according to the length of the abutment screw; each group included three assemblies. The screws were tightened to 30 Ncm and subjected to 2,000 thermocycles in water baths at 4°C and 60°C, with 60 seconds of immersion at each temperature. Removal torque values (RTVs) were measured before and after thermocycling, and differences in RTVs according to abutment screw length pre- and post-thermocycling were analyzed statistically.nnnRESULTSnMean RTVs before and after thermocycling were as follows: 23.0±4.4 Ncm and 25.5±0.9 Ncm for 1.4-mm-long abutment screws, 26.7±2.5 and 24.5±2.6 Ncm for 1.8-mm screws, 26.0±1.3 and 25.0±1.8 for 2.2-mm screws, 25.0±2.0 and 25.3±0.8 for 2.6-mm screws, 22.5±4.4 and 22.5±0.5 for 3.0-mm screws, 26.5±2.3 and 25.2±1.3 for 3.4-mm screws, and 25.5±4.8 and 23.2±0.8 for 3.8-mm screws, respectively. As the screw length increased, no statistically significant differences were found in the mean RTVs among the groups before or after thermocycling. Additionally, none of the groups showed significant changes in RTVs after cyclic thermal stress.nnnCONCLUSIONnAbutment screw length had no significant effect on screw loosening under thermal stress. From the results of this study, daily temperature changes in the oral cavity may have no negative influence on the integrity of an implant-abutment joint when a minimum of three and a half threads of an abutment screw are engaged.

A Long-Term Prospective Evaluation of Marginal Bone Level Change Around Different Implant Systems.

PURPOSEnThe purpose of this prospective study was to assess the change of marginal bone level around three different types of external-hex implants after 5 years using radiography.nnnMATERIALS AND METHODSnIncluded in this study were 54 patients randomly put into three different groups; rough-surface implants (Brånemark), machined coronal aspect implants (Restore), and microthreaded coronal aspect implants (Hexplant). Clinical and radiographic assessments were performed contemporaneously with implant loading (baseline) and at 1, 3, and 5 years post-functional loading. A mixed-model analysis was employed to examine mean marginal bone change significance in the three treatment groups.nnnRESULTSnIn a total of 31 out of 54 patients, 81 of 135 implants remained to the end of the study. At 5 years, the microthreaded coronal aspect implants had 0.61 ± 0.32 mm mean crestal bone loss; the rough-surface implants without microthread, 0.99 ± 0.38 mm; and the machined coronal aspect implants, 1.06 ± 0.39 mm. The rough-surface implants and the machined coronal aspect implants did not exhibit statistically significantly different marginal bone loss, whereas the microthreaded coronal aspect implants exhibited significantly less marginal bone loss (P = .0015).nnnCONCLUSIONnIn this research, rough-surface implants with microthreads showed positive long-term effects in preserving peri-implant bone level against functional loads when compared with implants lacking these aspects at the coronal part. Most of the bone loss was shown within 1 year of loading, and all types of implants stabilized after 1 year.

Cellular Response of Anodized Titanium Surface by Poly(Lactide-co-Glycolide)/Bone Morphogenic Protein-2

Background:The purpose of this study is to examine physical characteristics of and initial biological properties to anodized titanium treated with poly(d,l-lactide-co-glycolide) (PLG) mixed with recombinant human bone morphogenic protein-2 (rhBMP-2).Methods:Titanium specimens were prepared in groups of four as follows: group NC was anodized under 300xa0V as control; group PC was anodized then dropped and dried with solution 0.02xa0ml PLG; group D was anodized then dropped and dried with solution 0.02xa0ml PLG/rhBMP-2 (3.75xa0μg per disc); and group E was anodized then coated with 0.02xa0ml PLG/rhBMP-2 (3.75xa0μg per disc) by electrospray. Human osteoblastic-like sarcoma cells were cultured. Cell proliferation and alkaline phosphatase (ALP) activity test were carried out. Runx-2 gene was investigated by the reverse transcription-polymerase chain reaction. Immunofluorescence outcome of osteogenic proteins was observed.Results:After 3xa0days, there were significantly higher proliferations compared rhBMP-2 loaded titanium discs with rhBMP-2 unloaded discs. The ALPase activity on rhBMP-2 loaded titanium discs was significantly higher than in rhBMP-2 unloaded discs. The expression level of Runx2 mRNA presented the highest on the PLG/rhBMP-2-coated surface.Conclusion:PLG polymers mixed with rhBMP-2 might improve proliferation, differentiation and osteogenic protein formation of cells on the anodized titanium.

Osteoclastic Response on Titanium Surfaces in Modified Simulated Body Fluid

PURPOSEnIt was hypothesized that calcium phosphate (CaP) deposition onto Ti surfaces using biomimetic deposition contributed to not only improving osteogenesis but also suppressing osteoclastogenesis in terms of high surface hydrophilicity.nnnMATERIALS AND METHODSnTi discs with two different surfaces were prepared: machined and anodic oxidized surfaces. The specimens of two different surfaces were soaked in modified simulated body fluid solution for 14 days at physiologic condition. Murine RAW 264.7 cells were utilized as osteoclast precursor cells. To evaluate osteoclast differentiation activity on Ti surfaces, tartrate-resistant acid phosphatase activity assay was conducted, and cells on Ti discs were investigated with a field emission-scanning electron microscope (FE-SEM). The expression of nuclear factor of activated T cells 1 (NFATc1) and c-Fos, two critical transcriptional factors involved in osteoclastogenesis, were also assessed in terms of mRNA and protein levels by real-time reverse transcriptase-polymerase chain reaction and western blot, respectively.nnnRESULTSnTartrate-resistant acid phosphatase activities on both machined and anodic oxidized Ti surfaces soaked in modified simulated body fluid were significantly lower compared with nonimmersed ones. FE-SEM observation showed that the number of differentiated osteoclasts was lower on anodic oxidized surfaces immersed in modified simulated body fluid compared with nonimmersed Ti surfaces. Protein and mRNA expression of NFATc1 and c-Fos were significantly decreased on anodic oxidized Ti surfaces immersed in modified simulated body fluid compared with those on nonimmersed ones. The effects of immersion of Ti discs in modified simulated body fluid on osteoclastogenesis were higher on anodic oxidized surfaces than on machined surfaces.nnnCONCLUSIONnIt can be concluded that osteoclastogenesis was inhibited by biomimetic deposition using modified simulated body fluid, especially on anodic oxidized Ti surfaces.