Osteogenic evaluation of collagen membrane containing drug-loaded polymeric microparticles in a rat calvarial defect model

The aim of this study was to develop a functional collagen membrane that is treated with poly (lactic-co-glycolic acid) (PLGA) nanoparticles loaded with dexamethasone (DEX) as a bioactive molecule for guided bone regeneration (GBR). The DEX-loaded PLGA microparticles prepared using water-in-oil standard emulsion method were precoated with positively charged polyethylenimine molecules and later immobilized onto the surface of the collagen membrane; the microparticles were physically immobilized using counter charges of positively charged PLGA microparticles and the negatively charged collagen membrane surface. The release profile of DEX over a 4-week immersion study indicated an initial burst release followed by a sustained release. The performance of this system was investigated using rats with calvarial bone defects. The in vivo evaluation of the defects filled with membrane containing DEX-loaded PLGA microparticles indicated enhanced volume and quality of new bone formation compared with defects that were either unfilled or filled with membrane alone. This innovative platform for bioactive molecule delivery more potently induced osteogenesis, which may be exploited in implantable membranes for stem cell therapy or improved in vivo performance. In conclusion, this newly developed collagen membrane treated with drug-loaded PLGA microparticles might be applicable as a promising bone graft substitute for GBR.

A comparative analysis of patients with mesiodenses: a clinical and radiological study

Objectives

A mesiodens appears most commonly as a supernumerary tooth impacted in the anterior maxilla. The purpose of this study is analyze mesiodens clinically.

Materials and Methods

Gender, crown form, direction of impaction, relation to permanent incisors, and chief complaints of patients with extracted mesiodens were analyzed.

Results

Patients were analyzed for motivation to visit the hospital; 85.4% of the patients were referred from other hospitals. Mesiodens was more common in males than in females (3.7:1), and 70.1% of patients had only one mesiodens, while 29.6% had two mesiodenses. Of the mesiodenses, 61.4% were of the aconical form, and the most common direction was upward (62.4%), followed by the normal position (26.0%) and the horizontal position (11.6%). The mesiodenses caused orthodontic problems with the permanent incisors in 46.3% of cases. Mesiodens associated with dentigerous cyst was rarely observed in our patient group.

Conclusion

Mesiodens is more common in males than in females and often affects the permanent incisors. Thus, careful clinical and radiological evaluations of mesiodenses are important.

A Comparative Study of Stability After the Installation of 2 Different Surface Types of Implants in the Maxillae of Dogs

PURPOSE

This study was performed to investigate the histologic and histomorphometric findings of 2 different types of implant.

MATERIALS AND METHODS

Resorbable blasting media (RBM) and sandblasted with larger grit and acid etched (SLA) surfaced implants (24 fixtures in each group) were installed in posterior maxilla of dogs. The initial stability was measured using Periotest (Periotest value [PTV]). After 6 or 12 weeks, fixtures with surrounding bone were harvested.

RESULTS

The average initial stability of the SLA group (-1.71 ± 2.9) was higher than that of the RBM group (-1.25 ± 3.21), but there was no significant difference. The mean PTV of the RBM surface was higher than the SLA surface at 12 weeks. The average bone-implant contacts were 67.6% ± 16.0% at 6 weeks and 82.7% ± 8.6% at 12 weeks in the SLA group and 69.9% ± 17.6% at 6 weeks and 78.3% ± 9.2% at 12 weeks in the RBM group.

CONCLUSION

The SLA and resorbable blasting media (RBM) surface implants demonstrated good stabilities and healing processes of the surrounding bone in the posterior maxilla. Therefore, the two domestic implants could provide predictable clinical results.

Mesenchymal dental pulp cells attenuate dentin resorption in homeostasis

Dentin in permanent teeth rarely undergoes resorption in development, homeostasis, or aging, in contrast to bone that undergoes periodic resorption/remodeling. The authors hypothesized that cells in the mesenchymal compartment of dental pulp attenuate osteoclastogenesis. Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells [DPCs]) and alveolar bone (alveolar bone cells [ABCs]) were isolated and separately cocultured with primary rat splenocytes. Primary splenocytes readily aggregated and formed osteoclast-like cells in chemically defined osteoclastogenesis medium with 20 ng/mL of macrophage colony-stimulating factor (M-CSF) and 50 ng/mL of receptor activator of nuclear factor κB ligand (RANKL). Strikingly, DPCs attenuated osteoclastogenesis when cocultured with primary splenocytes, whereas ABCs slightly but significantly promoted osteoclastogenesis. DPCs yielded ~20-fold lower RANKL expression but >2-fold higher osteoprotegerin (OPG) expression than donor-matched ABCs, yielding a RANKL/OPG ratio of 41:1 (ABCs:DPCs). Vitamin D3 significantly promoted RANKL expression in ABCs and OPG in DPCs. In vivo, rat maxillary incisors were atraumatically extracted (without any tooth fractures), followed by retrograde pulpectomy to remove DPCs and immediate replantation into the extraction sockets to allow repopulation of the surgically treated root canal with periodontal and alveolar bone-derived cells. After 8 wk, multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resoprtion alternating with areas of osteodentin formation in root dentin surface in the observed 8 wk. These findings suggest that DPCs of the mesenchymal compartment have an innate ability to attenuate osteoclastogenesis and that this innate ability may be responsible for the absence of dentin resorption in homeostasis. Mesenchymal attenuation of dentin resorption may have implications in internal resorption in the root canal, pulp/dentin regeneration, and root resorption in orthodontic tooth movement.

Relationship between mandibular condyle and angle fractures and the presence of mandibular third molars

OBJECTIVES

We retrospectively evaluated the impact of mandibular third molars on the occurrence of angle and condyle fractures.

MATERIALS AND METHODS

This was a retrospective investigation using patient records and radiographs. The sample set consisted of 440 patients with mandibular fractures. Eruption space, depth and angulation of the third molar were measured.

RESULTS

Of the 144 angle fracture patients, 130 patients had third molars and 14 patients did not. The ratio of angle fractures when a third molar was present (1.26 : 1) was greater than when no third molar was present (0.19 : 1; odds ratio, 6.58; P<0.001). Of the 141 condyle fractures patients, the third molar was present in 84 patients and absent in 57 patients. The ratio of condyle fractures when a third molar was present (0.56 : 1) was lower than when no third molar was present (1.90 : 1; odds ratio, 0.30; P<0.001).

CONCLUSION

The increased ratio of angle fractures with third molars and the ratio of condyle fractures without a third molar were statistically significant. The occurrence of angle and condyle fractures was more affected by the continuity of the cortical bone at the angle than by the depth of a third molar. These results demonstrate that a third molar can be a determining factor in angle and condyle fractures.

Evaluation of bone formation after grafting with deproteinized bovine bone and mineralized allogenic bone

PURPOSE

The purpose of this study was to evaluate the ability of new bone formation of deproteinized bovine bone (Bio-Oss) and mineralized allogenic bone (Tutoplast).

MATERIALS AND METHODS

Sixty rats were divided into control and experimental groups (groups 1 and 2): control group, unfilled control; group 1, Bio-Oss; group 2, Tutoplast, respectively. The animals were killed after 6 and 12 weeks, and newly formed bone was analyzed histomorphometrically.

RESULTS

In the control group, some new bone formed in the rim of the defect area. In the group 1, newly formed bone was thinner than the adjacent normal bone, and Bio-Oss particles were observed. In the group 2, showed a pattern of gradual fusion with adjacent bone, as well as particles in some areas, similar to the Bio-Oss-treated group. In the 12-week groups, the amount of new bone formation was significantly higher in the experimental groups than in the control group, and it was significantly higher in group 2 than in group 1.

CONCLUSION

Although Tutoplast and Bio-Oss graft materials seem to be useful for bone grafts, Tutoplast showed more active new bone formation than Bio-Oss.

Berberine induces FasL-related apoptosis through p38 activation in KB human oral cancer cells

In the present study, we examined the anticancer properties of berberine in KB oral cancer cells with a specific focus on its cellular mechanism. Berberine did not affect the cell viability of the primary human normal oral keratinocytes that were used as a control. However, the viability of KB cells was found to decrease significantly in the presence of berberine in a dose-dependent manner. Furthermore, in KB cells, berberine induced the fragmentation of genomic DNA, changes in cell morphology, and nuclear condensation. In addition, caspase-3 and -7 activation, and an increase in apoptosis were observed. Berberine was also found to upregulate significantly the expression of the death receptor ligand, FasL. In turn, this upregulation triggered the activation of pro-apoptotic factors such as caspase-8, -9 and -3 and poly(ADP-ribose) polymerase (PARP). Furthermore, pro-apoptotic factors such as Bax, Bad and Apaf-1 were also significantly upregulated by berberine. Anti-apoptotic factors such as Bcl-2 and Bcl-xL were downregulated. Z-VAD-FMK, a cell-permeable pan-caspase inhibitor, suppressed the activation of caspase-3 and PARP. These results clearly indicate that berberine-induced cell death of KB oral cancer cells was mediated by both extrinsic death receptor-dependent and intrinsic mitochondrial-dependent apoptotic signaling pathways. In addition, berberine-induced upregulation of FasL was shown to be mediated by the p38 MAPK signaling pathway. We also found that berberine-induced migration suppression was mediated by downregulation of MMP-2 and MMP-9 through phosphorylation of p38 MAPK. In summary, berberine has the potential to be used as a chemotherapeutic agent, with limited side-effects, for the management of oral cancer.

Horizontal ridge expansion and implant placement using screws: a report of two cases

Implants are typically placed after performing ridge expansion by inserting screws of gradually increasing thickness and good clinical outcomes are often obtained. We placed 11 implants in 6 patients, and one implant failed during osseointegration but it was replaced immediately after removal and successful prosthetic treatments were completed. During these surgeries, buccal cortical plate complete fractures do not occur. Inserting screws for ridge expansion is a successful and predictable technique for implant placement in narrow alveolar bone.

Comparative Study of the Early Loading of Resorbable Blasting Media and Sandblasting with Large-grit and Acid-etching Surface Implants: A Retrospective Cohort Study

Purpose:

This study compares the prognosis (the survival rate and marginal bone loss) of resorbable blasting media (RBM) surface implants and sandblasting with large-grit and acid-etching (SLA) surface implants in the early loading.

Methods:

This study targeted 123 patients treated by implants installation from January 2008 to March 2010. The loading was initiated in the maxilla within three to four months and in the mandible within one to two months. The types of restoration were single crown and fixed partial prosthesis. Those functioned over one year. The implants were classified by the surface of implants as Group 1: RBM surface (GS III; OSSTEM, Busan, Korea) and, Group 2: SLA surface (Superline; Dentium, Seoul, Korea). The groups were categorized by maxilla and mandible and compared by survival rate, marginal bone loss through clinical records evaluation, and radiographic measurements.

Results:

The marginal bone loss in the maxilla was 0.14±0.34 mm (Group 1) and 0.30±0.37 mm (Group 2), a statistically significant difference (P <0.05). In the mandible those were 0.28±0.54 mm (Group 1) and 0.20±0.33 mm (Group 2), not significant (P >0.05). There was no significant difference of marginal bone loss between maxilla and mandible by groups. During observation there was no implant failure, a survival rate of 100%.

Conclusion:

Both surfaces showed an excellent survival rate, and the marginal bone loss was not substantial.

Osteocalcin/fibronectin-functionalized collagen matrices for bone tissue engineering

Collagen is the most abundant protein found in the extracellular matrix and is widely used to build scaffolds for biomedical applications which are the result of its biocompatibility and biodegradability. In the present study, we constructed a rhOCN/FNIII9-10 fusion protein and rhOCN/FNIII9-10-functionalized collagen matrices and investigated the potential value for bone tissue engineering. In vitro studies carried out with preosteoblastic MC3T3-E1 cells showed that rhOCN/FNIII9-10 fusion protein promoted cell adhesion and the mRNA levels of osteogenic markers including osteocalcin, runt-related transcription factor 2, alkaline phosphatase (ALP), and collagen type I. In addition, rhOCN/FNIII9-10-functionalized collagen matrices showed significant induction of the ALP activity more than rhFNIII9-10-functionalized collagen matrices or collagen matrices alone. These results suggested that rhOCN/FNIII9-10-functionalized collagen matrices have potential for bone tissue engineering.

Cold testing of quasi-optical mode converters using a generator for non-rotating high-order gyrotron modes

In this paper, we test the performance of a quasi-optical, internal-gyrotron mode converter. When cold testing mode converters, a rotating higher-order mode is commonly used. However, this requires a nontrivial design and precise alignment. We thus propose a new technique for testing gyrotron mode converters by using a simple, non-rotating, higher-order mode generator. We demonstrate the feasibility of this technique for a W-band gyrotron quasi-optical mode converter by examining the excitation of a TE6,2 mode from a non-rotating mode generator. Our results demonstrate that this new cold-test scheme is an easy and efficient method for verifying the performance of quasi-optical mode converters.

Relative adrenal insufficiency in chronic liver disease: its prevalence and effects on long-term mortality

BACKGROUND

The relationship between relative adrenal insufficiency (RAI) and chronic liver disease is unclear.

AIM

To determine the frequency with which RAI is observed in noncritically ill patients at various stages of chronic liver disease, and the correlation between RAI and disease severity and long-term mortality.

METHODS

In total, 71 non-critically ill patients with liver cirrhosis (n = 54) and chronic hepatitis (n = 17) were evaluated prospectively. A short stimulation test (SST) with 250 μg of corticotrophin was performed to detect RAI. RAI was defined as an increase in serum cortisol of <9 μg/dL in patients with a basal total cortisol of <35 μg/dL.

RESULTS

RAI was observed in only 13 (24.1%) of 54 patients with cirrhosis. Compared to those without RAI, cirrhotic patients with RAI had significantly higher Child-Turcotte-Pugh score (10.3 ± 1.7 vs. 7.1 ± 1.8, mean ± s.d., P < 0.001) and Model for End-Stage Liver Disease score (14.5 ± 6.6 vs. 9.4 ± 3.7, P = 0.017). The cortisol response to corticotropin was negatively correlated with the severity of cirrhosis (P < 0.05). In addition, the mortality rate was higher in cirrhotic patients with RAI (69.2%) than in those without RAI (4.9%; P < 0.001) during the follow-up period of 20.1 ± 13.5 months (range, 5.8-51.1 months). The cumulative 1-year survival rates in cirrhotic patients with and without RAI were 69.2% and 95.0%, respectively (P = 0.05), while the corresponding cumulative 3-year survival rates were 0% and 95.0% (P < 0.001).

CONCLUSIONS

Relative adrenal insufficiency is more commonly observed in those with severe cirrhosis, and is clearly associated with more advanced liver disease and a shortened long-term survival. This suggests that relative adrenal insufficiency is an independent prognostic factor in non-critically ill patients with cirrhosis.

A Clinical Study of Mandibular Angle Fracture

PURPOSE

To establish management protocol for mandibular angle fracture, we describe pertinent factors including cause, impacted third molar and recent treatment tendency.

METHODS

We examined the records of 62 patients who had unilateral mandibular angle fracture. Sixty patients who had open reduction surgery were examined at postoperative weeks 1, 4, 8, 12, and 28.

RESULTS

Left mandibular angle fracture is frequent in younger males. Presence of the mandibular third molar can increase fracture risk. Because of attached muscle, favorable fractures occurred primarily in the mandibular angle area.

CONCLUSION

Extracting the mandibular third molar can prevent angle fractures, and open reduction with only one plate adaptation is generally the proper treatment method for mandibular angle fracture.

Prognosis of closure of large sinus membrane perforations using pedicled buccal fat pads and a resorbable collagen membrane: case series study

For large membrane perforations that develop during sinus-bone grafting, we performed repairs using a pedicled buccal fat pad and a resorbable collagen membrane simultaneously with the bone graft. This study included eight patients. Postoperative maxillary sinusitis developed in two patients, which we managed with incision and drainage, and antibiotics. Ultimately, six patients received 12 implants, three of which failed (75% success). Implant replacement was performed after the removal of the failed replacement, at which point the prosthetic treatment was considered complete. In all of the six cases that we were able to follow-up with, the sinus-bone graft was healing favorably. We observed that the sinus bone height decreased gradually with time. Based on these case series, we conclude that our procedure of repairing large sinus-membrane perforations with a pedicled buccal fat pad and a collagen membrane is a reliable technique.

Osteogenic ability according to the decalcified modality of auto-tooth bone grafts in peri-implant defects in dogs

PURPOSE

The purpose of this study was to evaluate the bone generation capacity of the autotransplantation material with clinical and histological analyses after controlled acid treatment conditions.

MATERIAL AND METHODS

Bony defects were formed in the femur. Then, autotransplantation material was grafted after hydroxyapatite-coated implant placement. Experimental groups were classified according to the acid treatment method: 2% H2SO4 (group 1), 2% HCl (group 2), 2% HNO3 (group 3), or 2% ethylenediaminetetraacetic acid (EDTA) (group 4).

RESULTS

The new bone formation area and bone-implant contact (BIC) of the autotransplantation materials were measured after 8 weeks. The new bone formation area in experimental groups 2, 3, and 4 were greater than that in the control group (no graft) and in experimental group 1 at 8 weeks, and the BIC of experimental group 4 was greater than that in the control group and in experimental group 1; these differences showed statistical significance (P < 0.05).

CONCLUSION

Auto-tooth bone treated with EDTA resulted in more effective bone formation in dogs' femurs than bone treated with other solutions.

Resorption of bone graft after maxillary sinus grafting and simultaneous implant placement

OBJECTIVES

The purpose of this study was to evaluate the sinus bone graft resorption over 3 years after two-stage implant placement.

MATERIALS AND METHODS

The subjects for this study included 30 patients whose maxillary posterior ridges were too atrophic for implants. Bone-added osteotome sinus floor elevation was used in 15 maxillary sinuses, while the bone graft by lateral approach technique was used in 25 maxillary sinuses. The height from the top of the fixture to the sinus floor was estimated immediately after implant placement and the follow-up period was over 3 years. The surgery was classified with two groups: sinus bone grafting with and without autogenous bone. All implants were placed simultaneously.

RESULTS

The mean vertical bone loss was 3.15±2.95 mm. The survival rate of implants was 94.7%.

CONCLUSION

The amount of bone resorption was not significantly associated with the surgical methods, the type of bone graft materials used, or sinus perforation during surgery.

The seven-year cumulative survival rate of Osstem implants

OBJECTIVES

This study was performed to analyze the cumulative survival rate of Osstem implants (Osstem Implant Co., Ltd.) over a seven-year period.

MATERIALS AND METHODS

A total of 105 patients who had 467 Osstem implants that were placed at the Section of Dentistry, Seoul National University Bundang Hospital (Seongnam, Korea) from June 2003 through December 2005 were analyzed. The life table method and a cross-tabulation analysis were performed to evaluate the cumulative survival rate. The log rank test was used to evaluate the survival curve. The influence that the prognostic factors had on the survival rate was determined with a Cox proportional hazard model based on logistic regression analysis [corrected].

RESULTS

The seven-year cumulative survival rate of Osstem implants was 95.37%. The Cox proportional hazard model revealed that the following factors had a significant influence on survival rate; increased diameter, reduced prosthetic loading period and performance of bone grafting.

CONCLUSION

The osstem implants showed satisfactory results over the seven-year study period.

The treatment of malocclusion after open reduction of maxillofacial fracture: a report of three cases

The posttraumatic complications of jaw fractures related to jaw function and facial deformity include nonunion, malunion, malocclusion, temporomandibular joint dysfunction and facial asymmetry. This report presents cases referred to our department for revision of malunion and malocclusion following inadequate reduction of jaw fractures. Three patients with posttraumatic malocclusions caused by malunion were treated with a LeFort I osteotomy in one case and re-fracture in two cases. All of the patients exhibited stable results without further complications (e.g., malunion or malocclusion). Accurate preoperative diagnosis and proper anatomical reduction of the fracture segments are essential to preventing post-surgical malunion and malocclusion.

Downregulation of adenomatous polyposis coli by microRNA-663 promotes odontogenic differentiation through activation of Wnt/beta-catenin signaling

MicroRNAs (miRNAs) regulate cell differentiation by inhibiting mRNA translation or by inducing its degradation. However, the role of miRNAs in odontogenic differentiation is largely unknown. In this present study, we observed that the expression of miR-663 increased significantly during differentiation of MDPC-23 cells to odontoblasts. Furthermore, up-regulation of miR-663 expression promoted odontogenic differentiation and accelerated mineralization without proliferation in MDPC-23 cells. In addition, target gene prediction for miR-663 revealed that the mRNA of the adenomatous polyposis coli (APC) gene, which is associated with the Wnt/β-catenin signaling pathway, has a miR-663 binding site in its 3'-untranslated region (3'UTR). Furthermore, APC expressional was suppressed significantly by miR-663, and this down-regulation of APC expression triggered activation of Wnt/β-catenin signaling through accumulation of β-catenin in the nucleus. Taken together, these findings suggest that miR-663 promotes differentiation of MDPC-23 cells to odontoblasts by targeting APC-mediated activation of Wnt/β-catenin signaling. Therefore, miR-663 can be considered a critical regulator of odontoblast differentiation and can be utilized for developing miRNA-based therapeutic agents.