Jun-Beom Park

Effects of titanium brush on machined and sand‐blasted/acid‐etched titanium disc using confocal microscopy and contact profilometry

OBJECTIVE Mechanical techniques, including scaling with metal, plastic, or ultrasonic instruments, rubber cup polishing, air-powder abrasive system and brushing with a conventional or a rotating brush, have been used for the debridement of dental implants. Recently, rotating brushes with titanium bristles (titanium brush) have been introduced for the debridement of implant surface when peri-implant osseous defects occur. The purpose of this study was to evaluate the effects of a titanium brush on machined (MA) and sand-blasted and acid-etched (SA) titanium surfaces using scanning electron microscopy, confocal microscopy and profilometry. Moreover, correlations between the two quantitative evaluation methods (confocal microscopy and contact profilometry) were assessed. MATERIALS AND METHODS Both MA and SA discs were treated with rotating titanium brush at 300 rpm under irrigation for a total of 40 s. Roughness measurements were taken with confocal microscopy and surface profilometry. Then, the MA and SA surfaces were evaluated using scanning electron microscopy to determine the changes of the surface properties. RESULTS Untreated MA surface demonstrated uniform roughness with circumferential machining marks, and scratch lines over the original surfaces were observed after treatment with the titanium brush. Similarly, the titanium brush produced noticeable changes on the SA titanium surfaces. However, this treatment with titanium brush did not significantly change the roughness parameters, including the arithmetic mean height of the surface (Sa) and the maximum height of the surface (Sz), in both MA and SA surfaces. Correlations between two evaluation methods showed a Pearson correlation coefficient of 0.98 with linear regression R(2) of 0.96. CONCLUSION This study showed that the treatment with the titanium brush did not significantly change the roughness parameters, including Sa and Sz, in both MA and SA surfaces. Correlations between confocal microscopy and surface profilometry showed high correlation with a Pearson correlation coefficient of 0.98.

Effects of Asiasari radix on the morphology and viability of mesenchymal stem cells derived from the gingiva

Medicinal herbs used in traditional Oriental medicine, which have been in use clinically for thousands of years, are attractive sources of novel therapeutics or preventatives. Asiasari radix (A. radix) has been suggested for use in the treatment of dental diseases, including toothache and aphthous stomatitis. The aim of this study was to evaluate the effects of A. radix extracts on the morphology and viability of human stem cells derived from the gingiva. An Asiasarum heterotropoides extract was centrifuged and freeze-dried in a lyophilizer. Stem cells derived from the gingiva were grown in the presence of A. radix at concentrations ranging between 0.1 µg/ml and 1 mg/ml (0, 0.1, 1, 10, 100 and 1,000 µg/ml). Cell morphology was evaluated with an optical microscope and the viability of the cells was quantitatively analyzed with a cell counting kit-8 (CCK-8) assay for up to seven days. The untreated control group exhibited normal fibroblast morphology. The shapes of the cells following 0.1, 1, 10 and 100 µg/ml A. radix treatments were similar to those of the control group. However, a significant change was noted in the 1,000 µg/ml group on day 1, when compared with the untreated group. Furthermore, on day 7, the shapes of the cells following 100 and 1,000 µg/ml A. radix treatments were rounder and fewer cells were present, when compared with those of the control group. The cultures that grew in the presence of A. radix did not exhibit any changes in the CCK‑8 assay on day 2; however, significant reductions in cell viability were noticed following 100 and 1,000 µg/ml A. radix treatment on days 5 and 7. Within the limits of this study, A. radix influenced the viability of the stem cells derived from the gingiva. Thus, the direct application of A. radix to oral tissues may produce adverse effects at high doses. Therefore, the concentration and application time of A. radix requires meticulous control to obtain optimal results. These effects require consideration, if the use of A. radix is planned for the treatment of dental diseases.

Associations between the number of natural teeth in postmenopausal women and duration of lactation: The 2010–2012 Korea National Health and Nutrition Examination Survey

OBJECTIVES Lactation is reported to be associated with changes in maternal calcium homeostasis. The relationship between lactation and long-term oral health remains to be revealed. This study was aimed to evaluate the relationship between lactation and the number of natural teeth in postmenopausal women using nationally representative data. METHODS The data from the Korea National Health and Nutrition Examination Survey between 2010 and 2012 were used, and the analysis in this study was confined to 4211 respondents over 19 years old who had gone through menopause and had no missing values for the reproductive factors and outcome variables. The total number of natural teeth was then calculated after excluding third molars. Multiple logistic regression analyses were used to assess the associations of the number of natural teeth and lactation. RESULTS As the duration of total lactation increased, the number of natural teeth decreased. Average duration of lactation per child showed similar trends. The association between the total duration of lactation and the number of natural teeth showed an inverse relationship with a beta value of -0.0181 per day after adjustment, and the beta value of the average duration of lactation per child was -0.0287 after the adjustment. The odds ratios of the percentage of individuals with the number of teeth ≤ 27 tended to increase with increased duration of lactation. Adjusted odds ratios and 95% confidence intervals were 1.830 (1.009, 3.320); 1.142 (0.765, 1.704); 1.159 (0.807, 1.664); and 0.857 (0.563, 1.306) for lactation period of ≥ 25 months, 13-24 months, 7-12 months, ≤ 6 months, and no lactation, respectively. CONCLUSIONS This study investigated the relationship between the number of teeth and the total duration of lactation or an average duration of lactation per child using nationally representative data. Total duration of lactation and average duration of lactation per child were inversely related to the number of natural teeth. Lactation may be considered to be an independent risk indicator for tooth loss in Korean postmenopausal women.

Low dose of doxycyline promotes early differentiation of preosteoblasts by partially regulating the expression of estrogen receptors

BACKGROUND The tetracycline (TC) family, including minocycline and doxycycline (DC), has long been used in the medical field owing to its well-characterized antimicrobial properties. Moreover, TCs have been reported to have effects on bone formation and bone metabolism. Results have shown that more new bone formation is achieved when TCs have been applied in combination with bone graft material. METHODS In the present study, the effects of TCs (TC, minocycline, and DC) on osteoprecursor cells were evaluated. The cell viability was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Differentiation and mineralization were evaluated using an alkaline phosphatase activity test and alizarin red-S staining. In addition, the expression of proteins related to bone formation, such as estrogen receptor (ER)-α, bone morphogenetic protein receptor-IA, bone morphogenetic protein-2, and phospho-Smad1/5, were evaluated by using Western blot analysis. RESULTS The morphology of the cells seemed normal, and their viability was not affected in the treated groups compared with the control. Alkaline phosphatase activity significantly increased in cultures grown in the presence of 0.1 and 1.0 μM of DC. No statistically significant increase in the mineralization was seen the treated groups. The results of the Western blot analysis revealed that the addition of DC upregulated ER-α, bone morphogenetic protein-2, and phospho-Smad1/5 expression with a statistically significant difference in ER-α expression. CONCLUSIONS From our findings, it was concluded that a low dose of DC could produce positive effects on the differentiation of osteoprecursor cells at an early stage. Our results also suggested that DC has osteoinductive effects that were achieved mainly through the ER pathway by enhancing the expression of ER-α.

Effects of ultrasonic scaler tips and toothbrush on titanium disc surfaces evaluated with confocal microscopy.

Purpose Instrumentation to remove plaque from dental implants may cause damage to the implant surface, and previous studies that have evaluated the effects of the ultrasonic scalers and brushing in experimental settings reported that substantial changes were seen on implant surfaces after mechanical plaque removal. There is limited information on changes of the surface profile and roughness of sandblasted acid-etched (SLA) and machined titanium surfaces after treatment with different instruments in simulated clinical situations. The purpose of this study was to evaluate the effects of oral hygiene instruments including various types of ultrasonic tips in simulated clinical settings and brushing with dentifrice on machined and SLA titanium surface with confocal microscopy. Methods Both SLA and machined discs were treated with various ultrasonic scaler tips and brushing. Discs were either instrumented with 4 different ultrasonic scaler tips or brushed with dentifrice. The entire top surface of the discs was instrumented for a total of 40 seconds (20 seconds, 2 cycles). Brushing with dentifrice was done for 40 seconds. Roughness measurements were performed using a confocal microscope. Results The change of surface structure after different treatment modalities could be observed with the naked eye when compared with the untreated surface (SLA and machined groups). In case of SLA surfaces, the 2 metal tips produced greater changes on the titanium surfaces when compared with the plastic ultrasonic tips and brushing. On the machined discs, scratch lines over the original surfaces could be observed from all ultrasonic metal and plastic tips, but 2 metal tips produced significant and definite scratches on the original disc surfaces. Conclusions This study showed the effects of different types of ultrasonic tips and brushing with dentifrice on both SLA and machined titanium surfaces in simulated clinical setting. Within the limits of our study, we suggest that metal or plastic ultrasonic scaler tips may be applied as usual to treat the SLA surface of dental abutment or fixture surfaces without increasing the irregularities on the titanium surfaces. However, in case of machined surfaces, ultrasonic metal tips cannot be recommended because the surface becomes rougher after treatment. In addition, brushing of titanium, regardless of surface treatment (SLA and machined surfaces), resulted in reduction of surface roughness. Meticulous oral hygiene with brushing must be reinforced for the patients with dental implants to maintain the exposed implant surface clean. Brushing with dentifrice may facilitate maintaining the exposed fixture surface clean by smoothening the surface.

The Effect of Surface Treatment of Titanium with Sand-Blasting/Acid-Etching or Hydroxyapatite-Coating and Application of Bone Morphogenetic Protein-2 on Attachment, Proliferation, and Differentiation of Stem Cells Derived from Buccal Fat Pad

This study was performed to evaluate the effect of surface treatment of titanium, including: machined (MA), sand-blasted and acid-etched (SA), and hydroxyapatite-coated (HA) surfaces, and application of bone morphogenetic protein-2 (BMP-2) on attachment, proliferation, and differentiation of stem derived from buccal fat pad. Stem cells were isolated from buccal fat pad. Stem cells were cultured on MA, SA, and HA titanium discs with and without BMP-2. Cellular attachment and alkaline phosphatase (ALP) activity were evaluated at day 3, 7, and 14. Osteocalcin expression was performed using immunofluorescent assay. The cells grown on MA surface demonstrated good attachment with spindle-like morphology, and cells grown on SA and HA surfaces demonstrated more stellate-like morphology. An increase of ALP activity was seen in the rough surface (SA and HA groups) and a statistically significant increase was seen in the HA group (p < 0.05). The addition of BMP-2 made an expression of osteocalcin, and the highest expression of osteocalcin was noted in the HA group. Within the limits of this study, surface modification of titanium surfaces by sand-blasting/acid-etching or hydroxyapatite-coating was not able to allow the stem cells to differentiate into osteoblasts without exogenous soluble factors. The addition of BMP-2 showed osteogenic differentiation of stem cells and HA-coated surfaces demonstrated the highest ALP and osteocalcin expression.

Comparison of stem cells derived from periosteum and bone marrow of jaw bone and long bone in rabbit models

There is increasing interest in the therapeutic potential of stem cells because stem cells are promising candidates for the regeneration of tissue and treatment of diseases. Increasing evidence supports, multipotent stem cells may be obtained postnatally in different organs and tissues including bone marrow, synovium, adipose tissue, muscle and dental pulp. To determine a suitable cell source, the stem cells derived from periosteum and bone marrow of jaw bone(mandible) and long bone(tibia) were compared using rabbit models (JPO: periosteum from jaw-bone, JBM: bone marrow from jaw-bone, LPO: periosteum from long-bone, and LBM: bone marrow from long-bone). This study evaluated the proliferation and multilineage differentiation of the cells and clearly showed that expansion ability of JPO was higher than that of bone marrow derived cells. Comparisons of four different stem cells indicated that JPO group is the highest osteogenic potential. Moreover, this study has demonstrated that JPO, JBM and LBM are superior in terms of osteogensis and JPO, LPO and LBM are superior in terms of chondrogensis. Collectively, stem cells derived from jaw bone periosteium revealed highest osteogenic properties with relatively low morbidity with higher availability. Thus, it can be suggested that that periosteum from the jaw bone may be considered as optimal candidate for source of pluripotent stem cells with multi-germline potential with highest expansion ability and osteogenicity.

Comparative effects of chlorhexidine and essential oils containing mouth rinse on stem cells cultured on a titanium surface

Chlorhexidine (CHX) and Listerine (LIS), an essential oil compound, are the two commonly used adjunctive agents for mechanical debridement, for reducing the bacterial load in the treatment of peri-implant inflammation. However, antimicrobial agents have been reported to be cytotoxic to the alveolar bone cells and gingival epithelial cells. The present study was performed to examine the effects of antiseptics CHX and LIS, on the morphology and proliferation of stem cells. Stem cells derived from the buccal fat pad were grown on machined titanium discs. Each disc was immersed in CHX or LIS for 30 sec, 1.5 min or 4.5 min. Cell morphology was evaluated with a confocal laser microscope and the viability of the cells was quantitatively analyzed with the cell counting kit-8 (CCK-8). The untreated cells attached to the titanium discs demonstrated well-organized actin cytoskeletons. No marked alterations in the cytoskeletal organization were observed in any of the treated groups. The treatment with CHX and LIS of the titanium discs decreased the viability of the cells grown on the treated discs (P<0.05). The stem cells derived from the buccal fat pad were sensitive to CHX and LIS, and a reduction in cellular viability was observed when these agents were applied to the discs for 30 sec. Further studies are required to determine the optimal application time and concentration of this antimicrobial agent for maximizing the reduction of the bacterial load and minimizing the cytotoxicity to the surrounding cells.

Establishment of the chronic bone defect model in experimental model mandible and evaluation of the efficacy of the mesenchymal stem cells in enhancing bone regeneration

Stem cells can be isolated postnatally in different tissues including bone marrow, adipose tissue, muscle, and periosteum. Research has been performed using stem cell combined with scaffold to regenerate bony defect. The aim of this study was (1) to establish the chronic bone defect model for studying bone regeneration in alveolar process of rabbit mandible and (2) to evaluate the efficacy of the mesenchymal stem cell (MSC) derived from the mandible in enhancing bone regeneration. The defects measuring 6 (mesio-distal) × 4 (buscco-lingual) × 3 mm (apicocoronal) was prepared between the canine and the premolar area in New Zealand White rabbits. The defects were left untreated for 5 weeks to achieve chronic defect. The defect area was grafted with MSC loaded with deproteinized bovine bone (DBB) in test group. The positive control group was grafted with DBB only. No grafted group served as negative control. The average percentage of new bone formation at the test and control sites was determined at 4 weeks. Newly formed bone seemed to be integrated well with grafted particle. Test group (DBB+MSC) showed significant increase of bone when compared with positive control group (DBB) (p < 0.05). Within the limits of this study, it could suggest that the MSC from mandible may be considered as a treatment option in enhancing bone regeneration.

Treatment with various ultrasonic scaler tips affects efficiency of brushing of SLA titanium discs.

PurposeThe dental implant surface will be colonized by bacteria once it is exposed to the oral cavity. It is necessary to keep the titanium surface clean to prevent peri-implant diseases. Mechanical instrumentation is widely used, but this may cause damage to the implant surfaces. There is limited information whether surface change resulting from instrumentation influences the adherence of bacteria to the implant surface or influences the ease of removal of bacteria from the titanium surface by daily brushing. Therefore, this in vitro study was performed (1) to evaluate removal of Porphyromonas gingivalis from sand-blasted and acid-etched (SLA) titanium discs after the discs were instrumented by various ultrasonic scaler tips or brushed with a toothbrush with dentifrice using crystal violet assay and scanning electron microscopy (SEM), and (2) to assess the change of surface roughness after the treated discs were brushed with a toothbrush with dentifrice. Materials and MethodsSLA discs were treated with various ultrasonic scaler tips and a toothbrush. The titanium discs were incubated with P. gingivalis for 2 days after treatment (ultrasonic scales tips and brush) and then the disc surfaces were brushed for total of 40 seconds (20 seconds, two cycles) with a toothbrush with dentifrice. Differences in adhering bacteria were evaluated using crystal violet assay and SEM. Surface roughness of the treated discs after brushing with dentifrice was measured using confocal microscopy. ResultsThe change of surface structure was observed after different treatment modalities. Removal of bacteria was increased with the longer time of brushing, and the ultrasonic metal tip group displayed a significantly lower number of bacteria after brushing when compared to other groups. ConclusionsWithin the limits of this study, it may be suggested that when SLA surface is exposed to the oral cavity, it should firstly be treated with metal tips to smoothen the rough surface and thereby reduce attachment of bacteria and facilitate the removal of bacteria by daily oral hygiene procedures.