Takako Kawasaki

In Vivo Comparison of the Bone Regeneration Capability of Human Bone Marrow Concentrates vs. Platelet-Rich Plasma

Background Bone marrow aspirate concentrate (BMAC) including high densities of stem cells and progenitor cells may possess a stronger bone regenerative capability compared with Platelet-rich plasma (PRP), which contains enriched growth factors. The objective of this study was to evaluate the effects of human BMAC and PRP in combination with β-tricalcium phosphate (β-TCP) on promoting initial bone augmentation in an immunodeficient mouse model. Methodology/Principal Findings BMAC and PRP were concentrated with an automated blood separator from the bone marrow and peripheral blood aspirates. β-TCP particles were employed as a scaffold to carry cells. After cell counting and FACS characterization, three groups of nude mice (BMAC+TCP, PRP+TCP, and a TCP control) were implanted with graft materials for onlay placement on the cranium. Samples were harvested after 4 weeks, and serial sections were prepared. We observed the new bone on light microscopy and performed histomorphometric analysis. After centrifugation, the concentrations of nucleated cells and platelets in BMAC were increased by factors of 2.8±0.8 and 5.3±2.4, respectively, whereas leucocytes and platelets in PRP were increased by factors of 4.1±1.8 and 4.4±1.9, respectively. The concentrations of CD34-, CD271-, CD90-, CD105-, and CD146-positive cells were markedly increased in both BMAC and PRP. The percentage of new bone in the BMAC group (7.6±3.9%) and the PRP group (7.2±3.8%) were significantly higher than that of TCP group (2.7±1.4%). Significantly more bone cells in the new bone occurred in sites transplanted with BMAC (552±257) and PRP (491±211) compared to TCP alone (187±94). But the difference between the treatment groups was not significant. Conclusions/Significance Both human BMACs and PRP may provide therapeutic benefits in bone tissue engineering applications. These fractions possess a similar ability to enhance early-phase bone regeneration.

Assessment of skeletal stability of intraoral vertical ramus osteotomy with one-day maxillary-mandibular fixation followed by early jaw exercise.

PURPOSE Intraoral vertical ramus osteotomy (IVRO) is an effective surgical technique for cases of mandibular setback, is simpler and has a lower incidence of mental paraesthesia when compared to sagittal split ramus osteotomy (SSRO). However, IVRO has a disadvantage in the prolonged duration of postoperative maxillary-mandibular fixation (MMF) required due to the absence of rigid bone fixation. To avoid an extended MMF period, we developed a postoperative management protocol for our IVRO patients, using jaw exercises with elastic bands starting on the second day after surgery. METHODS We evaluated the cephalometric skeletal and dental stabilities of 16 IVRO patients as they followed our protocol. RESULTS The stabilities were confirmed and were similar to those of previous reports. CONCLUSION One-day MMF and early initiation of jaw exercise after IVRO did not affect the jaw position stability. Moreover, our findings suggest that starting jaw exercise earlier after IVRO surgery is beneficial, as it allows patients to avoid a long period of rigid MMF so that they can resume their normal daily activities sooner.

Administration of teriparatide improves the symptoms of advanced bisphosphonate-related osteonecrosis of the jaw: preliminary findings.

Teriparatide is a synthetic polypeptide hormone that contains the 1-34 amino acid fragment of the recombinant human parathyroid hormone that stimulates bone formation. Currently, it is approved only for the treatment of osteoporosis. The outcomes of daily teriparatide injections for the treatment of bisphosphonate-related osteonecrosis of the jaw in 10 patients are reported here. Two of the 10 cases dropped out due to adverse events. Of the remaining eight cases, seven exhibited clinical improvement of the jaw-related symptoms of osteonecrosis and progression of the sequestration, while one case did not show improvement of the symptoms. Administration of teriparatide in patients with osteonecrosis of the jaw promotes bone formation and subsequent sequestration over a short period of time. These results suggest that adjunctive teriparatide therapy is a viable and effective option for treating osteonecrosis of the jaw.

Short lingual osteotomy without fixation: a new strategy for mandibular osteotomy known as “physiological positioning”

We describe the strategy of physiological positioning, which we regard as a new alternative treatment to conventional orthognathic operations, and treated 18 patients with skeletal mandibular prognathism using it. The positions of SNB, FMA, and Me were measured postoperatively to assess skeletal stability, changes in the angle and perpendicular length of the upper and lower central incisors were measured to assess dental stability, and we confirmed that both skeletal and dental stability were excellent. The width to which the jaw could be opened recovered early, and we saw only one case of disorder of the temporomandibular joint. Short lingual osteotomy with physiological positioning is an effective new approach to the treatment of deformities of the mandible.

The skeletal stability after maxillo-mandibular osteotomy with a “physiological positioning strategy”

The aim of this study was to estimate skeletal and dental stability after maxillomandibular osteotomy with physiological positioning. Ten patients (7 men and 3 women) with skeletal mandibular prognathism were treated by conventional Le Fort I osteotomy for the maxilla and unfixed short lingual osteotomy for the mandible together with physiological positioning. We used cephalometric analysis to evaluate the skeletal and dental stability preoperatively, immediately after maxillomandibular osteotomy, and more than 1 year later. The immediately postoperative measurements for the SNA and the SN-palatal planes were 0.15° (p=0.67) and 1.0° (p=0.17), respectively. The positions of the anterior nasal spine, posterior nasal spine, and A point showed minimal changes 1 year postoperatively. The postoperative difference for SNB was 0.76° (p=0.04). Dental stability was apparent postoperatively. We conclude that reliable stability of both the maxilla and the mandible was achieved after maxillomandibular osteotomy with physiological positioning in patients with mandibular prognathism.

A Simplified and Systematic Method to Isolate, Culture, and Characterize Multiple Types of Human Dental Stem Cells from a Single Tooth

This chapter describes a simplified method that allows the systematic isolation of multiple types of dental stem cells such as dental pulp stem cells (DPSC), periodontal ligament stem cells (PDLSC), and stem cells of the apical papilla (SCAP) from a single tooth. Of specific interest is the modified laboratory approach to harvest/retrieve the dental pulp tissue by minimizing trauma to DPSC by continuous irrigation, reduction of frictional heat from the bur rotation, and reduction of the bur contact time with the dentin. Also, the use of a chisel and a mallet will maximize the number of live DPSC for culture. Steps demonstrating the potential for multiple cell differentiation lineages of each type of dental stem cell into either osteocytes, adipocytes, or chondrocytes are described. Flow cytometry, with a detailed strategy for cell gating and analysis, is described to verify characteristic markers of human mesenchymal multipotent stromal cells (MSC) from DPSC, PDLSC, or SCAP for subsequent experiments in cell therapy and in tissue engineering. Overall, this method can be adapted to any laboratory with a general setup for cell culture experiments.

Oral Rehabilitation With Orthognathic Surgery After Dental Implant Placement for Class Iii Malocclusion With Skeletal Asymmetry and Posterior Bite Collapse.

Increasing numbers of older patients are seeking orthognathic surgery to treat jaw deformity. However, orthodontic and orthognathic surgical treatment is difficult in cases without occlusal vertical stop. A 55-year-old man presented with Class III malocclusion and mandibular protrusion including esthetic problems and posterior bite collapse. He underwent dental implant treatment to reconstruct an occlusal vertical stop before orthognathic surgery. His occlusal function and esthetic problems improved after surgery, and his skeletal and occlusal stability has been maintained for 6 years. Dental implant placement at appropriate positions could help to determine the position of the proximal segment at orthognathic surgery and could shorten the time required to restore esthetic and occlusal function. This case demonstrates how skeletal and dental stability can be maintained long after surgery in a patient with jaw deformity and posterior bite collapse.

The three-dimensional assessment of dynamic changes of the proximal segments after intraoral vertical ramus osteotomy

Objectives: The aim of this study was to assess the positional changes of the proximal segments after intraoral vertical ramus osteotomy (IVRO). Method: Fifteen patients underwent IVRO and were followed according to the authors’ unique postoperative management regimen. The analyses of the positions and angles of the proximal segments were performed on frontal and lateral cephalograms, which were taken before surgery (T1) and within 3 days (T2), at 4 weeks (T3), and later than 6 months after surgery (T4). The three-dimensional positions of the condylar heads were also assessed by CT images, which were taken before and 1 year after surgery. Results: The proximal segments temporarily swung posteriorly and laterally with a center on the condylar head as a fulcrum point at T2 and T3, compared with T1, and they repositioned at T4. The condylar heads moved inferior approximately 2 mm with lateral rotation one year after surgery, as seen in the CT. Discussion: The condylar heads changed their positions physiologically for newly established jaw movement after IVRO with the authors’ post-operative management regimen because the post-operative skeletal stability and the jaw function were good and stable using this method.

Transient Exposure to Hypoxic and Anoxic Oxygen Concentrations Promotes Either Osteogenic or Ligamentogenic Characteristics of PDL Cells.

Abstract The periodontal ligament (PDL) has a reservoir of mesenchymal stem cells (MSCs) and this tissue is easily available following teeth removal procedures. However, PDL-derived cells (PDLCs) availability for tissue engineering is limited because they are heterogeneous cells at various differentiation and lineage commitments. Therefore, efficient culture conditions to increase MSCs number are needed to use PDLCs in tissue engineering. Recent reports indicate that low-oxygen conditions amplified stem/progenitor cell numbers and inhibited cell differentiation. Our aim was to establish which low-oxygen culture conditions favored bone or tendon/ligament regeneration in cultured PDLCs. Human PDLCs were cultured and exposed to either hypoxic (O2≤5%) or anoxic (O2<0.1%) oxygen conditions in low-glucose/serum-free media for 24 hours. After 24 h, as expected, cell survival was significantly less in PDLCs exposed to anoxic conditions as compared with cells under normal or hypoxic conditions. PDLCs exposed to hypoxic conditions had the highest percentages for MSC markers (CD105, CD166, Stro-1). For both hypoxic and anoxic conditions, stem cell marker genes (oct4, sox2, p75) were upregulated after 6 h. At 24 h, these stem cell markers were maintained in PDLCs under hypoxic condition. Interestingly under anoxic conditions, expression of scleraxis gene (a key transcription factor for tendo/ligamentogenesis) was upregulated markedly. When hypoxic PDLCs were subcultured into osteogenic medium, in vitro calcification and prominent in vivo bone formation in mice calvaria were observed. When anoxic PDLCs were subcultured into tendo/ligamentogenic medium, expression of aggrecan (a mature tenogenic gene) increased remarkably. No obvious differences were detectable on chondrogenic and adipogenic inducibilities. We propose that transient exposure to low-oxygen during the culture enhanced MSC population in PDL. In addition, different low-oxygen concentrations favored osteogenic or tendo/ligamentogenic inducibilities of cultured PDLCs.

A Patient With Severe Maxillary Gingival Exposure Treated With Combined Compression Osteogenesis of the Anterior Alveolar Bone and Conventional Le Fort I Osteotomy

Abstract Excessive gingival exposure at the maxillary anterior region during not only smiling (a gummy face) but also at rest creates both functional and aesthetic problems for patients. We herein introduce a unique treatment procedure for mandibular retrognathia with a gummy face. This procedure combines conventional Le Fort I osteotomy and following corticotomy at the anterior region of the maxilla. Subsequently, the anterior segment is continuously compressed (compression osteogenesis) in a posterior-superior direction until it reaches an ideal position. This procedure appears to safely and adequately resolve both the aesthetic and functional complaints associated with patients with a gummy face.