Irisin promotes odontogenic differentiation and angiogenic potential in human dental pulp cells.

AIM: To determine whether irisin, a newly discovered myokine that links exercise-induced and metabolic homeostasis, is able to promote odontogenic differentiation and angiogenesis in human dental pulp cells (HDPCs). METHODOLOGY: Cell viability in the presence of irisin was measured. Real-time PCR and Western blot analysis were performed to evaluate the expression levels of irisin, odontogenic and angiogenic markers. The involvement of mitogen-activated protein kinase (MAPK) and the protein kinase B (Akt) signalling pathway was evaluated by Western blot. To evaluate mineralization nodule formation, alkaline phosphatase (ALP) staining and alizarin red S staining were performed. Scratch wound assays were performed to evaluate the effects of irisin on cell migration. The data were analysed using one-way analysis of variance (anova) followed by Tukey post hoc test and Student's t-test. Statistical significance was considered at P < 0.05. RESULTS: Irisin significantly promoted odontogenic differentiation as evidenced by formation of mineralized nodules, induction of ALP activity and upregulation of odontogenic and angiogenic markers (P < 0.05). Scratch wound assays revealed that irisin significantly increased migration of HDPCs (P < 0.05). Phosphorylation of both MAPK and Akt was increased by irisin. MAPK and Akt inhibitors inhibited mineralization, cell migration and the increased expression of odontogenic and angiogenic markers. CONCLUSIONS: Irisin promoted odontogenic differentiation and mineralization and has the potential for angiogenesis through activation of the MAPK and Akt signalling pathways in HDPCs.

Solvent-exposed lipid tail protrusions depend on lipid membrane composition and curvature.

The stochastic protrusion of hydrophobic lipid tails into solution, a subclass of hydrophobic membrane defects, has recently been shown to be a critical step in a number of biological processes like membrane fusion. Understanding the factors that govern the appearance of lipid tail protrusions is critical for identifying membrane features that affect the rate of fusion or other processes that depend on contact with solvent-exposed lipid tails. In this work, we utilize atomistic molecular dynamics simulations to characterize the likelihood of tail protrusions in phosphotidylcholine lipid bilayers of varying composition, curvature, and hydration. We distinguish two protrusion modes corresponding to atoms near the end of the lipid tail or near the glycerol group. Through potential of mean force calculations, we demonstrate that the thermodynamic cost for inducing a protrusion depends on tail saturation but is insensitive to other bilayer structural properties or hydration above a threshold value. Similarly, highly curved vesicles or micelles increase both the overall frequency of lipid tail protrusions as well as the preference for splay protrusions, both of which play an important role in driving membrane fusion. In multi-component bilayers, however, the incidence of protrusion events does not clearly depend on the mismatch between tail length or tail saturation of the constituent lipids. Together, these results provide significant physical insight into how system components might affect the appearance of protrusions in biological membranes, and help explain the roles of composition or curvature-modifying proteins in membrane fusion.

The sphingosine-1-phosphate receptor 1 binding molecule FTY720 inhibits osteoclast formation in rats with ligature-induced periodontitis.

BACKGROUND AND OBJECTIVE: Osteoclast precursors (OPs) re-migrate from the bone surface into blood vessels through sphingosine-1-phosphate receptor 1 (S1PR1) expression. T cells also express S1PR1, mediating their migration from the lymph nodes into blood vessels. OP and T-cell migration are one of the sequential steps related to osteoclast formation. To characterize the role of S1PR1 in osteoclast formation induced by periodontitis, we investigated the effect of S1PR1-binding molecule FTY720 (FTY) on the number of OPs and T cells in periodontal tissue and peripheral blood of rats with ligature-induced periodontitis. MATERIAL AND METHODS: Rats were divided into four groups; control (Con), FTY, periodontitis (Peri), and periodontitis+FTY (Peri+FTY) groups. Ligatures were placed around the first molars in the left and right mandibles. The rats were intraperitoneally injected with vehicle or 3 mg/kg FTY daily until they were killed. The number of osteoclasts and cluster of differentiation (CD)11b, CD3 and receptor activator of NF-κB ligand (RANKL)-positive cells in first molar furcation were counted by tartrate-resistant acid phosphatase or immunohistochemistry staining. The number of CD11b- and CD3-positive cells in peripheral blood was estimated by flow cytometry. RESULTS: The number of osteoclasts in the Peri group was higher than Con, Peri+FTY and FTY groups (p < 0.05) and CD11b, CD3 and RANKL-positive cells were also higher in the Peri group than other groups in furcation (p < 0.05). While CD11b-positive cells in furcation of the Peri+FTY group were lower than the Peri group (p < 0.05), they were higher in peripheral blood (p < 0.05). Dissimilar to CD11b-positive cells, CD3-positive cells in the Peri+FTY group were lower in peripheral blood as well as furcation than the Peri group (p < 0.05). RANKL-positive cells in furcation of the Peri+FTY group were also lower than Peri group (p < 0.05). CONCLUSION: These results indicate that FTY may facilitate re-migration of OPs from the alveolar bone surface into blood vessels, blocking T-cell migration from the lymph nodes into blood vessels and subsequently reducing osteoclast formation induced by periodontitis. This suggests that S1PR1-S1P binding may play a role in osteoclast formation of periodontitis by modulating OP and T-cell migration.

Changes in psychological health, subjective food intake ability and oral health-related quality of life during orthodontic treatment.

Assessing changes in patient's psychological health and oral health-related quality of life (OHRQoL) over time during orthodontic treatment may help clinicians to treat patients more carefully. To evaluate changes in mental health, self-reported masticatory ability and OHRQoL during orthodontic treatment in adults, this prospective study included 66 adults (30 men, 36 women; mean age, 24·2 ± 5·2 years). Each patient completed the Korean versions of the State-Trait Anxiety Inventory, Zung Self-Rating Depression Scale, Rosenberg self-esteem scale, key subjective food intake ability (KFIA) test for five key foods and Oral Health Impact Profile-14 (OHIP-14K) at baseline (T0), 12 months after treatment initiation (T1) and debonding (T2). All variables changed with time. Self-esteem and the total OHIP-14K score significantly decreased and increased, respectively, at T1, with a particular increase in the psychological and social disabilities scores. There were no significant differences in any questionnaire scores before and after treatment. The total OHIP-14K score was positively correlated with trait anxiety and depression, and negatively correlated with self-esteem and KFIA at T0, regardless of the treatment duration. Older patients showed a significant increase in the total OHIP-14K score at T1 and T2. OHRQoL worsened with an increase in the treatment duration. Our results suggest that OHRQoL temporarily deteriorates, with the development of psychological and social disabilities, during orthodontic treatment. This is related to the baseline age, psychological health and self-reported masticatory function. However, patients recover once the treatment is complete.

Periodontal healing with a preameloblast-conditioned medium in dogs.

BACKGROUND AND OBJECTIVE: The predictability of conventional periodontal treatments for damaged periodontal tissue is limited, particularly on the regeneration of new cementum. As signaling molecules, a range of growth factors has been used to promote periodontal regeneration on periodontal ligament (PDL) and cementum defects. A preameloblast-conditioned medium (PA-CM) was prepared from cultured murine apical bud cells, which can differentiate into ameloblasts. We examined the effect of PA-CM on PDL cells and cementoblasts in vitro and evaluated histologically the effects of PA-CM on the regeneration of experimentally induced periodontal defects in vivo. MATERIAL AND METHODS: In vitro, the effects of PA-CM on the migration of human PDL cells were examined using a scratch wound healing assay and a transwell assay. The differentiation and mineralization potential of PA-CM-treated human PDL cells and murine cementoblastic OCCM-30 cells was examined by real-time polymerase chain reaction and Alizarin red-S staining. In vivo, six mongrel dogs (12-16 kg; 6-8 mo old) were used. Twenty-four roots were replanted with either, (i) only periodontal defects (n = 12; control group), or (ii) periodontal defects and PA-CM treatment (n = 12; experimental group). In the experimental group, the PDL and cementum between notches was removed using a Gracey curette and soaked in 0.08 mL water containing 80 µg of a PA-CM for 2 min. The dogs were killed at 4 and 8 wk post-surgery. RESULTS: The in vitro results showed that PA-CM stimulated the migration of PDL cells and promoted the differentiation and mineralization of PDL cells and cementoblasts. Real-time polymerase chain reaction analysis revealed stronger expression of Runx2, Osx, OC, Bsp and Cap mRNAs in the PA-CM-treated PDL cells and cementoblasts than those in the control cells. In vivo, newly formed PDL-like tissue and cementum-like tissue were observed partially between the root surfaces and newly formed bone in the experimental group. The regenerated PDL-like tissue in the experimental group was significantly higher than that in the control group at 8 wk (p < 0.05). The replacement resorption on the experimental group was significantly lower than that in the control group at 8 wk (p < 0.05). In addition, the amount of newly formed cementum-like tissue in the experimental group was significantly higher than that in the control group at 4 and 8 wk (p < 0.05). CONCLUSION: These results suggest that PA-CM has the potential to regenerate periodontal tissues in PDL and cementum defects.

Periodontitis mainly increases osteoclast formation via enhancing the differentiation of quiescent osteoclast precursors into osteoclasts.

BACKGROUND AND OBJECTIVES: Tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts are formed in sequential steps: proliferation and differentiation of hematopoietic progenitors into quiescent osteoclast precursors (QOPs), followed by fusion of QOPs. In this study, we investigated whether enhancement of osteoclast formation by periodontitis is derived from the stimulation of proliferation of hematopoietic progenitors or the differentiation of QOPs into osteoclasts. MATERIAL AND METHODS: Ligatures were placed around the first molars in the left mandibles of Fischer 344 inbred rats. The rats received drinking water containing bromodeoxyuridine (BrdU) (which can be incorporated into dividing nuclei) after ligation during the experimental period. The number of inflammatory cells in the distal area was counted. Alveolar bone loss was histologically estimated by measuring the distance from the cementoenamel junction to the alveolar bone crest in the distal area and determining the percentage of periodontal ligament area in the furcation. The number of osteoclasts and percentage of BrdU(+) nuclei in total osteoclasts nuclei were counted after TRAP and BrdU double labeling. RESULTS: The number of polymorphonuclear cells increased on day 1 and then rapidly decreased. The number of mononuclear cells increased in a time-dependent manner up to day 5 and remained the same until day 10. Alveolar bone loss of ligatured teeth increased in a time-dependent manner. The number of osteoclasts peaked on day 3 then gradually decreased. At peak, the percentage of BrdU(+) nuclei in total osteoclasts nuclei in the distal and furcation areas were 7.9% and 4.1%, respectively. CONCLUSION: These results indicate that most of the osteoclasts formed after periodontitis induction are derived from preformed QOPs, suggesting that enhancement of osteoclast formation by periodontitis might be mainly caused by stimulating the differentiation of QOPs into osteoclasts.

Postoperative hypoalbuminemia as a risk factor for surgical site infection after oral cancer surgery.

OBJECTIVES: Postoperative surgical site infection (SSI) is a frequent postoperative complication in patients with oral cancer and significantly affects patient recovery and medical expenses. The aim of this study was to examine the predictors of SSI in patients undergoing major surgery for oral or oropharyngeal squamous cell carcinoma (OSCC) and to determine the relationship between perioperative albumin and the development of SSI. SUBJECTS AND METHODS: In 337 consecutive patients who underwent clean-contaminated surgery for OSCC, serum albumin, glucose, and hemoglobin levels were perioperatively measured. Differences between the groups were examined using Fisher's exact test, Mann-Whitney U-test, and multiple logistic regression analysis. RESULTS: Surgical site infection was detected in 88 (26.1%) patients with median time to development of 10 (2-25) days. Multiple logistic regression analysis showed that only postoperative serum albumin < 2.5 g dl(-1) was an independent variable predictive of SSI (P = 0.003). The duration of hospital stay was negatively correlated with postoperative albumin (R(2) = -0.302, P < 0.001). CONCLUSION: Early postoperative hypoalbuminemia <2.5 g dl(-1) is an independent risk factor for the development of SSI in patients undergoing oral cancer surgery. Clinicians should be aware of the implications of postoperative hypoalbuminemia and consider more intensive postoperative care in these patients.

Diabetic characteristics and alveolar bone loss in streptozotocin- and streptozotocin-nicotinamide-treated rats with periodontitis.

BACKGROUND AND OBJECTIVE: Experimental models showing variable diabetic status are necessary to understand the relationship between diabetes and periodontitis. The streptozotocin (STZ)-induced diabetes model allows control of diabetic status by nicotinamide (NA), which protects against STZ-induced ß-cell necrosis. Therefore, we compared diabetic characteristics and alveolar bone loss in STZ- and STZ-NA-treated rats with periodontitis. MATERIAL AND METHODS: STZ-treated rats were generated by intravenous (IV) administration of STZ (50 mg/kg). STZ-NA-treated rats were induced by intraperitoneal administration of NA (270 mg/kg) 15 min before IV administration of STZ (65 mg/kg). Periodontitis was induced by ligature around the left mandibular first molar 1 wk after injection. Blood glucose level, glucose tolerance and serum insulin levels were determined at day 0 and/or 20 after ligature. At day 20, tibia bone loss was assessed using micro-computed tomography and hematoxylin and eosin staining. Alveolar bone loss was histologically measured as the distance of the cementoenamel junction to the alveolar bone crest in distal and the percentage of periodontal ligament area in the first molar furcation, respectively. The number of inflammatory cells, receptor activator of nuclear factor kappa-B ligand (RANKL)-positive cells and the area of osteoid were determined. RESULTS: In STZ-treated rats, obvious hyperglycemia over 300 mg/dL and severe body weight loss were observed. The insulin level was approximately 14% compared to that of control rats. STZ-NA-treated rats were impaired in glucose tolerance compared to control rats; however, body weight and insulin levels were not significantly different. Tibia bone loss was increased in STZ-treated rats, but significant change was not observed in STZ-NA-treated rats compared to control rats. In ligatured teeth, alveolar bone loss was increased in both STZ- and STZ-NA-treated rats compared to control rats. Alveolar bone loss, the number of inflammatory cells and RANKL-positive cells in STZ-treated rats were greater than in STZ-NA-treated rats. The area of osteoid decreased in STZ-treated rats compared to control, but not STZ-NA-treated rats. CONCLUSION: These results indicate that STZ- and STZ-NA-treated rats exhibit diabetic characteristics similar to type 1 diabetes mellitus and a pre-diabetic state, respectively. In addition, alveolar bone loss in response to periodontitis and tibia loss depend on diabetic status. Diabetic status-dependent bone remodeling imbalance and inflammation could affect the alveolar bone loss in the two models. Both STZ- and STZ-NA-treated rats may be useful to investigate differences in periodontitis sensitivity associated with diabetic status and to develop therapeutic agents for periodontitis in patients with diabetes.

Socioeconomic disparities of periodontitis in Koreans based on the KNHANES IV.

OBJECTIVES: The aim of this study was to identify the socioeconomic factors associated with the prevalence of periodontitis in Koreans. METHODS: Cross-sectional data from 12 763 subjects, 15 years old and above, who underwent periodontal examinations were obtained from the Korean National Health and Nutrition Examination Survey IV (2007-209). Multivariate linear and logistic regression analyses were applied to estimate the association between socioeconomic indicators and prevalence of periodontitis. RESULTS: A significant association was found between increasing age and periodontitis. Participants with higher income were less likely to have periodontitis (aOR = 0.9 and 95% CI = 0.78-0.98, and aOR = 0.7 and 95% CI = 0.60-0.80 in the middle and highest quintiles of monthly household income, respectively). In addition, participants living in rural areas were less likely to have periodontitis (aOR = 0.9 and 95% CI = 0.81-0.99), and current smokers were more likely to have periodontitis (aOR = 1.7 and 95% CI = 1.49-1.89). The analysis of comorbidities revealed that individuals with diabetes mellitus (DM) were significantly more likely to have periodontitis (aOR = 1.4 and 95% CI = 1.18-1.68). CONCLUSIONS: In a rapidly increasing Korean population, the lower socioeconomic groups as well as individuals with DM were significantly more likely to present with periodontitis.

The effect of orally administered epigallocatechin-3-gallate on ligature-induced periodontitis in rats.

BACKGROUND AND OBJECTIVE: Epigallocatechin-3-gallate (EGCG) is known for its beneficial properties, including anti-inflammatory and anti-oxidative activities. Recently, reports have suggested that EGCG plays a pivotal role in regulating cytokine expression and osteoclastic activity. In the present study, we investigated whether orally administered EGCG has a therapeutic effect on ligature-induced periodontitis. MATERIALS AND METHODS: Forty-eight Sprague-Dawley rats were treated with EGCG or phosphate-buffered saline. Periodontitis was induced by tying a ligature for 7 d. After removing ligation, EGCG (200 mg/kg) or phosphate-buffered saline was administered via oral gavage on a daily basis. Rats were killed after 1, 2 and 4 wk of administration. Histologic and histomorphometric analyses, tartrate resistant acid phosphatase staining and immunohistochemistry were carried out. RESULTS: In the control group, bone loss did not recover even after the causative factor of periodontitis was eliminated. On the other hand, distance from cemento-enamel junction to alveolar bone crest, long junctional epithelium and collagen destruction were reduced in the EGCG group. Decreased interleukin (IL)-6 expression was shown from the early stage of EGCG administration, followed by reduced tumor necrosis factor (TNF) expression at week 4 EGCG group. The CT area showed a higher decrease of IL-6 expression between the control and EGCG group than alveolar bone area. Downregulation of TNF and IL-6 expression led to a decrease in osteoclast number and activity, which resulted in reduced bone loss. CONCLUSIONS: Systemic administration of EGCG could have a therapeutic effect on damaged periodontal tissue. Inhibited cytokine expression, including TNF and IL-6 is responsible for the reduction in osteoclast formation, osteoclastic activity and collagen destruction.

Scintigraphic evaluation of osseointegrative response around calcium phosphate-coated titanium implants in tibia bone: effect of platelet-rich plasma on bone healing in dogs.

Differential diagnoses for canine bone disease are commonly based on radiography. However, scintigraphy is a nuclear scanning test to trace bone healing during stress fracture and osteomyelitis and thus can be used to probe the osseointegration process in vivo in the context of the dental implant. The purpose of this study was to explore the possibility of using noninvasive scintigraphy to probe the effect of platelet-rich plasma (PRP) to enhance osseointegration of the implant and to confirm the result with a parallel histological examination in adult beagle dogs. Two independent calcium phosphate-coated titanium screw implants 8 mm in length and 4 mm in diameter were inserted into each tibia in 4 dogs (4 implants/animal, total = 16). The PRP-treated group was deposited with 0.5 ml of PRP into the drill hole in the right tibia; the control group was instilled with 0.5 ml of saline into the drill hole in the left counterpart before titanium screw implantation. Radiography of the implanted tibias showed complete osseointegration but no osteomyelitis. No difference in the ossification of the peri-implant bone on the radiographs was observed between the two groups during the experimental period. However, the scintigraphic findings revealed obvious differences in bone uptake between the two groups. The higher bone uptake in the PRP-treated group significantly increased bone activity and faster bone regeneration compared to the control group (p < 0.05) at 4 weeks after implantation. The percentage of the bone-to-implant contact on histological examination in the PRP-treated group showed dense cortical bone formation in close contact with the metallic surface of the titanium implant (p < 0.05). Quantitative histological analysis correlated well with that of the scintigraphic evaluation as revealed by Pearson correlation analysis (r = 0.72, p < 0.05). Thus, scintigraphy is a sensitive and noninvasive method suitable for osseointegration of the implant in vivo.

The dynamic healing profile of human periodontal ligament stem cells: histological and immunohistochemical analysis using an ectopic transplantation model.

BACKGROUND AND OBJECTIVE: Human periodontal ligament stem cells (hPDLSCs) have been reported to play the pivotal role in periodontal regeneration. However, the dynamic cellular healing process initiated by hPDLSCs still remains to be elucidated. In the present study, the sequence of regeneration by hPDLSCs was assessed using histological and immunohistochemical observation in an ectopic transplantation model, which is a well-standardized assessment tool that excludes the innate healing factors from the animals. MATERIAL AND METHODS: Human periodontal ligament stem cells that were isolated and characterized from teeth (n=12) extracted for the purpose of orthodontic treatment were transplanted with carriers into ectopic subcutaneous pouches in immunocompromised mice (n=20). Animals were killed after several different healing periods: 3 d (n=4), 1 (n=4), 2 (n=4), 4 (n=4) and 8 wk (n=4). Histological analysis for regenerated tissues formed by hPDLSCs was conducted using hematoxylin and eosin, Masson's trichrome and picrosirius red staining. In addition, immunohistochemical staining was performed to observe the sequential expression of osteogenic/cementogenic and periodontal ligament tissue-specific markers associated with periodontal regeneration. RESULTS: The whole healing process by transplanted hPDLSCs could be broadly divided into four distinctive phases. In the first phase, proliferated hPDLSCs migrated evenly all over the carrier, and collagenous tissues appeared in the form of amorphous collagen matrices. In the second phase, collagen fibers were well arranged among the carriers, and cementoid-like tissues were observed. In the third phase, the formation of mature collagen fibers, resembling Sharpey's fibers, was associated with active mineralization of cementum-like tissues, and in the fourth phase, the maturation of cementum-like tissues was observed on carrier surfaces. Various osteogenic/cementogenic markers related to the regeneration processes were expressed in a well-orchestrated time order. Interestingly, well-organized cementum-like and periodontal ligament fiber-like tissues and cells with early and late osteogenic/cementogenic markers were frequently observed in the secluded area of carrier surfaces. We termed this area the cell-rich zone. CONCLUSION: The results from this study clearly demonstrated the sequential histological changes during periodontal tissue regeneration by hPDLSCs. Understanding of this process would potentially enable us to develop better cell-based treatment techniques.

Deep Learning-Based Prediction of the 3D Postorthodontic Facial Changes.

With the increase of the adult orthodontic population, there is a need for an accurate and evidence-based prediction of the posttreatment face in 3 dimensions (3D). The objectives of this study are 1) to develop a 3D postorthodontic face prediction method based on a deep learning network using the patient-specific factors and orthodontic treatment conditions and 2) to validate the accuracy and clinical usability of the proposed method. Paired sets (n = 268) of pretreatment (T1) and posttreatment (T2) cone-beam computed tomography (CBCT) of adult patients were trained with a conditional generative adversarial network to generate 3D posttreatment facial data based on the patient's gender, age, and the changes of upper (ΔU1) and lower incisor position (ΔL1) as input. The accuracy was calculated with prediction error and mean absolute distances between real T2 (T2) and predicted T2 (PT2) near 6 perioral landmark regions, as well as percentage of prediction error less than 2 mm using test sets (n = 44). For qualitative evaluation, an online survey was conducted with experienced orthodontists as panels (n = 56). Overall, PT2 indicated similar 3D changes to the T2 face, with the most apparent changes simulated in the perioral regions. The mean prediction error was 1.2 ± 1.01 mm with 80.8% accuracy. More than 50% of the experienced orthodontists were unable to distinguish between real and predicted images. In this study, we proposed a valid 3D postorthodontic face prediction method by applying a deep learning algorithm trained with CBCT data sets.

Induction of bone formation by Escherichia coli-expressed recombinant human bone morphogenetic protein-2 using block-type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models.

BACKGROUND AND OBJECTIVE: The potential of the Escherichia coli-expressed recombinant human bone morphogenetic protein-2 (ErhBMP-2) to support new bone formation/maturation using a block-type of macroporous biphasic calcium phosphate (bMBCP) carrier was evaluated in an orthotopic and ectopic rat model. MATERIAL AND METHODS: Critical-size (Φ 8 mm) calvarial defects and subcutaneous pockets in 32 Sprague-Dawley rats received implants of rhBMP-2 (2.5 µg) in a bMBCP carrier or bMBCP alone (control). Implant sites were evaluated using histological and histometric analysis following 2- and 8-wk healing intervals (eight animals/group/interval). RESULTS: ErhBMP-2/bMBCP supported significantly greater bone formation at 2 and 8 wk (10.8% and 25.4%, respectively) than the control at 2 and 8 wk (5.3% and 14.0%, respectively) in calvarial defects (p < 0.01). Bone formation was only observed for the ErhBMP-2/bMBCP ectopic sites and was significantly greater at 8 wk (7.5%) than at 2 wk (4.5%) (p < 0.01). Appositional and endochondral bone formation was usually associated with a significant increase in fatty marrow at 8 wk. The bMBCP carrier showed no evidence of bioresorption. CONCLUSION: ErhBMP-2/bMBCP induced significant bone formation in both calvarial and ectopic sites. Further study appears to be required to evaluate the relevance of the bMBCP carrier.

Interproximal periodontal defect model in dogs: a pilot study.

OBJECTIVE: This study aimed to evaluate the validity of a surgically created interproximal periodontal defect in dogs. MATERIALS AND METHODS: Surgery was performed in the interproximal area between the maxillary second and third premolars in two beagle dogs. Following an incision and reflection of the gingival flap, a 3-mm wide and 5-mm high defect was prepared surgically at the interproximal area. A thorough root planing was performed and the flap was coronally positioned and sutured. The contra-lateral area was served as the control with no surgical intervention. After 8 weeks of healing, the animals were killed and the defect was analysed histometrically and radiographically. RESULTS: The interproximal periodontal defect resembled a naturally occurring defect and mimicked a clinical situation. After healing, the defect showed limited bone (0.89±0.02mm) and cementum regeneration (1.50± 0.48mm). CONCLUSIONS: Within the limitations of this pilot study, the interproximal periodontal defect showed limited bone and cementum regeneration. Thus, it can be considered as a standardized, reproducible defect model for testing new biomaterials.

Effect of Tack Cure on Polymerization Shrinkage of Resin-based Luting Cements.

CLINICAL RELEVANCE: Self-cure after tack cure could result in a lower polymerization shrinkage in some resin-based luting cements, which is closely related to lower degree of cure.

Liposome-complexed adenoviral gene transfer in cancer cells expressing various levels of coxsackievirus and adenovirus receptor.

PURPOSE: Loss of coxsackievirus and adenovirus receptor (CAR) is frequently observed in malignant cancer, hampering adenoviral gene therapy approaches. Complexing adenovirus with cationic liposomes can increase adenoviral transgene expression, particularly in cells with CAR-deficiency. We investigated whether other factors such as lipid composition might be involved in determining the efficiency of liposome-complexed adenoviral gene transfer in cancer cells. MATERIAL AND METHODS: Human cancer cell lines with different expression levels of CAR were infected with a GFP transgene. The efficiency of transgene expression was assessed by determining GFP expression using FACS analysis. RESULTS: The efficiency of liposome-complexed adenoviral gene transfer was dependent on the lipid composition constituting liposomes. Polyethylene glycol (PEG)-containing liposomes were most effective in increasing liposome-complexed adenoviral gene transfer. In CAR-deficient cells, use of PEG-containing liposomes enhanced adenoviral gene transfer, whereas in CAR-expressing cells enhancement varied depending on cell type. In some CAR-expressing cells, the effect of liposome complexing was even comparable to that in CAR-deficient cells. Increased adenoviral transgene expression following complexing with PEG-containing liposomes correlated with liposome uptake in cancer cells. CONCLUSIONS: Liposome-complexed adenoviral gene transfer appears to depend on lipid composition and the level of liposome uptake by cancer cells, in addition to CAR levels. Our study suggest that these multiple factors should be considered in designing liposome-complexed adenoviral vectors to improve outcomes of current adenoviral cancer gene therapies.

Protein release microparticles based on the blend of poly(D,L-lactic-co-glycolic acid) and oligo-ethylene glycol grafted poly(L-lactide).

Bovine serum albumin (BSA), a model protein drug, was encapsulated with a microparticle based on the blend of poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(L-lactide)-g-oligo(ethylene glycol) (PLLA-g-oligoEG). Effects of PLLA-g-oligoEG in the blend on degradation, characteristic properties, and release behavior of the microparticle were studied. Drug loading efficiency increased with increase in the graft frequency of oligoEG in the graft copolymer in the blend. The release of BSA was found to be more efficient for microparticles based on the blend than on the PLGA, which is due to the faster protein diffusion through the swollen phase of the hydrogel-like structure. The microparticles based on the blend showed a slower degradation and a lower pH shift compared to that of PLGA.

Cationic liposome-enhanced adenoviral gene transfer in a murine head and neck cancer model.

The effect of combining adenoviral vector and cationic liposomes on the efficiency of gene transfer to head and neck tumor cells was investigated. Two human and two murine cell lines were used for the screening of gene transfer efficiency using an adenoviral vector. Cationic liposome-enhanced gene transfer was checked using a murine squamous carcinoma cell line, SCCVII/SF. A considerable difference in the efficiency of gene transduction was observed among the cell lines. The combination of DOSPER and adenoviral vector containing human alkaline phosphatase showed a remarkable enhancing effect in gene transfer in vitro and in vivo, compared to the adenovirus alone or control groups. With an improvement in the efficiency of gene transfer, it may be possible not only to enhance the expression of transduced genes, but also to deliver a smaller amount of virus, as a result, reducing toxicity and the immune response against adenovirus.

Bone probing measurement as a reliable evaluation of the bone level in periodontal defects.

BACKGROUND: Evaluation of periodontal regeneration is usually made by clinical measurements despite their limitations in determining the precise nature of the healing response. In the present study, the possibility of using bone probing measurements under local anesthesia to determine bone level changes without a re-entry procedure was investigated. METHODS: Thirty-eight (38) first molars in 28 patients with chronic periodontitis who were scheduled to have periodontal surgery were included in this study. A custom-made acrylic resin stent was used for proper orientation of the probe for the bone probing depth measurement as well as probing depth measurements and surgical and radiographic bone level evaluations. The mesial, distal, and middle sites in the buccal aspect of each tooth were used. The sites were divided into 2 groups according to probing depth: those with a probing depth < 4 mm and those with a probing depth > or = 4 mm. RESULTS: The probing depth was not significant in the difference between actual bone level (SBL) and bone probing depth (BP) (P >0.05). The greatest correlation to SBL was found with BP (gamma = 0.92), followed by radiographic bone level (RBL) (gamma = 0.69). The morphology of the defects had no significant effect on the difference between SBL and other measurements, while tooth surface and probing depth had significant effects on the difference between RBL and SBL. CONCLUSIONS: The results of this study suggest that, regardless of probing depth, probing surface, and the presence of intrabony defects, there is a minimal difference between the BP and SBL. Determining the bone probing depth measurement is a kind of reliable method to estimate the regenerated bone level following periodontal treatment.