A new rationale for preservation of the mandibular third molar in orthognathic patients with missing molars

Controversies exist regarding the need for prophylactic extraction of mandibular third molars in patients who plan to undergo orthognathic surgery. An 18-year-old male patient was diagnosed with mandibular prognathism and maxillary retrognathism with mild facial asymmetry. He had a severely damaged mandibular first molar and a horizontally impacted third molar. After extraction of the first molar, the second molar was protracted into the first molar space, and the third molar erupted into the posterior line of occlusion. The orthognathic surgery involved clockwise rotation of the maxillomandibular complex as well as angle shaving and chin border trimming. Patients who are missing or have damaged mandibular molars should be monitored for eruption of third molars to replace the missing posterior tooth regardless of the timing of orthognathic surgery.

NELL-1 Increased the Osteogenic Differentiation and mRNA Expression of Spheroids Composed of Stem Cells

Background and objectives: NELL-1 is a competent growth factor and it reported to target cells committed to the osteochondral lineage. The secreted, osteoinductive glycoproteins are reported to rheostatically control skeletal ossification. This study was performed to determine the effects of NELL-1 on spheroid morphology and cell viability and the promotion of osteogenic differentiation of stem cell spheroids. Materials and Methods: Cultures of stem cell spheroids of gingiva-derived stem cells were grown in the presence of NELL-1 at concentrations of 1, 10, 100, and 500 ng/mL. Evaluations of cell morphology were performed using a microscope, and cell viability was assessed using a two-color assay and Cell Counting Kit-8. Evaluation of the activity of alkaline phosphatase and calcium deposition assays involved anthraquinone dye assay to determine the level of osteogenic differentiation of cell spheroids treated with NELL-1. Real-time quantitative polymerase chain reaction (qPCR) was used to evaluate the expressions of RUNX2, BSP, OCN, COL1A1, and β-actin mRNAs. Results: The applied stem cells produced well-formed spheroids, and the addition of NELL-1 at tested concentrations did not show any apparent changes in spheroid shape. There were no significant changes in diameter with addition of NELL-1 at 0, 1, 10, 100, and 500 ng/mL concentrations. The quantitative cell viability results derived on Days 1, 3, and 7 did not show significant disparities among groups (p > 0.05). There was statistically higher alkaline phosphatase activity in the 10 ng/mL group compared with the unloaded control on Day 7 (p < 0.05). A significant increase in anthraquinone dye staining was observed with the addition of NELL-1, and the highest value was noted at 10 ng/mL (p < 0.05). qPCR results demonstrated that the mRNA expression levels of RUNX2 and BSP were significantly increased when NELL-1 was added to the culture. Conclusions: Based on these findings, we conclude that NELL-1 can be applied for increased osteogenic differentiation of stem cell spheroids.

Vertical eruption patterns of impacted mandibular third molars after the mesialization of second molars using miniscrews

Objective: 

To investigate (1) whether vertical eruption of impacted third molars improves after mesialization of second molars and (2) what factors affect the vertical eruption of impacted third molars when space caused by missing molars is successfully closed by mesialization of the second molar using miniscrews.

Materials and Methods: 

The treatment group (Group 1) included 52 patients who had (1) missing mandibular first molars (ML-6) or missing deciduous mandibular second molars (ML-E), (2) initially impacted mandibular third molars, and (3) successful space closure of the edentulous area with orthodontics. Panoramic radiographs at start of treatment (T1) and at time of space closure (T2) were collected. The control group (Group 2) included 46 nonedentulous patients with impacted mandibular third molars without molar protraction treatment. Panoramic radiographs with similar T1/T2 treatment times were selected. Nine measurements were obtained regarding horizontal available space, vertical eruption, and third molar angulation.

Results: 

Third molars erupted vertically an average of 2.54 mm in Group 1 compared with 0.41 mm in Group 2. Age, gender, Nolla stage, and angle of the third molars did not show significant correlations with the vertical change of the impacted third molars, whereas the depth of third molar impaction and available space showed significant correlations.

Conclusions: 

Impacted mandibular third molars vertically erupt as a result of uprighting with mesialization of the second molar, and vertical eruption is affected by the initial vertical location of impacted third molars and available space.

Osteogenic potential of adult stem cells from human maxillary sinus membrane by Simvastatin in vitro: preliminary report

Objectives

The objective of this study is to determine the adequate concentration and to evaluate the osteogenic potential of simvastatin in human maxillary sinus membrane-derived stem cells (hSMSC).

Materials and Methods

Mesenchymal stem cells derived from the human maxillary sinus membrane were treated with various concentrations of simvastatin. The adequate concentration of simvastatin for osteogenic induction was determined using bone morphogenetic protein (BMP-2). The efficacy of osteogenic differentiation of simavastatin was verified using osteocalcin mRNA, and the mineralization efficacy of hSMSCs and simvastatin treatment was compared with alkaline phosphatase and von Kossa staining.

Results

Expression of BMP-2 mRNA and protein was observed after three days and was dependent on the concentration of simvastatin. Expression of osteocalcin mRNA was observed after three days in the 1.0 µM simvastatin-treated group. Mineralization was observed after three days in the simvastatin-treated group.

Conclusion

These results suggest that simvastatin induces the osteogenic potential of mesenchymal stem cells derived from the human maxillary sinus membrane mucosa.

Adult stem cells derived from human maxillary sinus membrane and their osteogenic differentiation

PURPOSE

To investigate the method and conditions of isolation and proliferation of multipotent mesenchymal stem cells (MSCs) from human maxillary sinus membrane in vitro and to induce osteogenic differentiation directly for identification.

MATERIALS AND METHODS

A human maxillary sinus membrane specimen was collected in aseptic conditions from an orthognathic surgery patient and cultured. The cells at passage three were sorted by flow cytometry and treated with osteogenic differentiation media. To determine the osteogenic potential of these cells, the authors analyzed alkaline phosphatase (ALP) expression, mineralization of extracellular matrix, and osteocalcin expression; staining with alizarin red and von Kossa and reverse-transcriptase polymerase chain reaction were also performed.

RESULTS

Maxillary sinus membrane-derived cells were positive for STRO-1 and CD105 and negative for CD34. After 7 days, ALP began to be expressed. After 21 and 28 days, most cells showed expression of ALP. Mineralization of the extracellular matrix was observed and, after 21 and 28 days, most of the cells showed mineralization. After 7 days, the osteocalcin gene was expressed; this expression was strongest on the 28th day.

CONCLUSIONS

The results suggest that there are MSCs in human maxillary sinus membrane tissue, which can be differentiated into osteoblasts under osteogenic induction. This indicates that maxillary sinus membrane may be a useful source of MSCs for cell therapy.

Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy

OBJECTIVE

The aim of this study was to evaluate condylar displacement in 3 dimensions by means of computed tomography after mandibular setback by sagittal split ramus osteotomy with rigid fixation and to compare these results with those from patients with mandibular advancement.

STUDY DESIGN

Thirty Korean subjects with skeletal class III malocclusion who had undergone mandibular setback by sagittal split ramus osteotomy had computed tomographs taken. Tomographs were taken to evaluate the temporomandibular joint 1 month before and approximately 1 month after surgery. The position and angulation of the condyle were measured on axial or sagittal views. These measurements were analyzed to determine any correlations between the amount of mandibular movement and condylar displacement.

RESULTS

The results of this study show that the condyle tends to move inferiorly and rotate inward on the axial view and backward on the sagittal view by a statistically significant amount.

CONCLUSION

The positional change of the condyle after sagittal split ramus osteotomy was not correlated with the amount of the setback.

Classification of Angle Class III malocclusion and its treatment modalities

To obtain the best results in the treatment of patients with Angle Class III malocclusion, the etiologies of the malocclusion should first be clarified, and then an appropriate treatment modality should be decided. Angle Class III malocclusions in 120 subjects who had orthognathic surgery were analyzed with cephalometrics and facial photos and classified into 3 categories based on the abnormalities of the maxilla. Type A is true mandibular prognathism, which means that the maxilla is normal but the mandible is overgrown. Type B is characteristic of the overgrown maxilla and mandible with anterior crossbite. Type C indicates a hypoplastic maxilla with anterior crossbite. Treatment modalities should be differentially decided according to this new classification of Angle Class III malocclusions.

Identification of a Salmonella typhimurium genomic region involved in invasion of HeLa and Henle-407 epithelial cells

To identify the invasion determinant, a cosmid library was constructed by cloning a genomic library of Salmonella typhimurium 82/6915 into a cosmid vector, pLA2917. A genomic region involved in invasion of cultured HeLa and Henle-407 cells was subcloned into plasmid pGEM-7Z. E. coli strain DH1 carrying pSV6235 consisting of a S. typhimurium 4.6 kb genomic region in pGEM-7Z showed invasion of cultured HeLa and Henle-407 cells. Nested sequential deletions were introduced into the 4.6 kb genomic region of pSV6235. The E. coli recombinants which contained less than 1.5 kb deletions from the 5' end (SmaI site) of the genomic region invaded the cells as effectively as DH1 (pSV6235). The invasion of the recombinants carrying over 2.0 kb deletions from the end of pSV6235 was significantly inactivated compared to DH1 (pSV6235). Restriction enzyme analysis showed that the 3.1 kb fragment from the 3' end of the 4.6 kb genomic region was distinguished from the Salmonella pathogenicity I genes of S. typhimurium such as the inv, spa, and hil regions showing invasion of the cultured eukaryotic cells.

Preparation of dendritic graft copolymer consisting of poly-(L-lysine) and arabinogalactan as a hepatocyte specific DNA carrier

The dendriTIc graft copolymers (PAX) consisting of a poly(L-lysine) (PLL) main chain and grafts of arabinogalactan (AG) were prepared as a liver cell-specific DNA carrier. The copolymers were successfully prepared by reductive amination reaction between a reductive end of AG and epsilon-amino groups of PLL using NaBH3CN as a catalyst. The fractionation of a low molecular weight fraction (Mn = 25 kDa) from a crude AG (Mn = 33 kDa) was essential for the reaction to proceed. The resulting copolymers were isolated by ultrafiltration from unreacted AG and characterized by 1H NMR and gel permeation chromatography equipped with a multiangle laser light scattering detector (GPC-MALLS). The binding and internalization of DNA to hepatoma cells, HepG2, were considerably enhanced by complexing DNA with PAX copolymers. The interactions between PAX/DNA complexes and HepG2 cells were thoroughly inhibited in the presence of a competitor to asialoglycoprotein receptors (ASGP-R), indicating high specificity of the complex to ASGP-R. Furthermore, the PAX copolymers allowed the expression of the reporter gene. Our results reveal that the PAX copolymers may provide a new research tool for cell-specific gene delivery and eventually enhance gene-therapy technology.

Comb-type copolymers for controlled DNA delivery

Various comb-type copolymer containing a polycation as a main chain was design to construct delivery systems of DNAs. The comb-type copolymers having cell-specific polysaccharides were proved to be useful to deliver DNA to the target cells in vivo. Of interest, the copolymers with abundant side chains of hydrophilic polymers are capable of stabilizing DNA triplex. Further, injectable nanoparticles for controlled releases of DNAs were fabricated from the copolymer and a biodegradable polymer.

Molecular analysis of the genes mediating Salmonella invasion

To identify invasion determinants, a genomic library of Salmonella typhimurium was cloned into a cosmid vector, pLA2917. A clone, pSI623 which was invasive for HEp-2 and Henle-407 epithelial cells, was subcloned into a plasmid vector, pGEM-7Z to define the invasion genes. The subclone, pSV6235 containing a 4.5 kbp fragment of the Salmonella genomic region, was highly invasive for HEp-2 and Henle-407 cells, compared with other subclones whose Salmonella genomic regions are 7.4, 6.3, 5.5 and 1.4 kbp, respectively. This study reflects that the invasion efficiency of the host strain, Escherichia coli to HEp-2 and Henle-407 cell lines was significantly increased by the introduction of the genomic region of the virulent S. typhimurium. Restriction enzyme analysis showed that there was a single PstI site on the 27 kbp of Salmonella genomic region of pSI623, and no PstI site was found on the 4.5 kbp of genomic region of pSV6235. This finding suggests that the invasion related genes different from the inv and spa gene clusters which were identified in S. typhimurium, may exist in genomic DNA of S. typhimurium.

Simple preparation of nanoparticles coated with carbohydrate-carrying polymers

Nanoparticles bearing carbohydrate chains on the surface can be prepared by the simple diafiltration method. The nanoparticles prepared by the present method displayed high yield, no-aggregation formation, small size, narrow size distribution, and one-step procedure. Also, the high density carbohydrate chains on the particles can be recognized by liver cells.