Bone regenerative medicine is an important dental implant treatment for cases with severe ridge resorption. We have been attempting to use autogeneous periosteum as a biomaterial for bone regeneration. In the present study, we evaluated the effects of intermittent injection of human parathyroid hormone (hPTH) prior to harvesting the periosteum, on the proliferation and differentiation of osteoblasts.
Using male Wistar rats, hPTH (1-34) (100 μg/kg) in physiological saline and physiological saline were intraperitoneally injected three times a week to the experimental and control groups, respectively. Then, circular pieces of pericranium 4 mm in diameter were harvested from the top of the cranium bone. The harvested periosteum pieces were cultured for 14 days and compared between the experimental and control groups.
Compared with the control group, the experimental group had a significantly greater increase in cell numbers and alkaline phosphatase (ALP) densely positive area. In the experimental group, on 7 days and 14 days proliferating cell nuclear antigen (PCNA)-positive and runt-related transcription factor 2 (RUNX2)-positive cells were observed. In addition, real-time PCR showed significant increases in bone morphogenetic protein 2 (BMP2), type I collagen (Col-I), ALP, osteonectin (ON), osteopontin (OPN), and osteocalcin (OC).
These results indicate that increased proliferation and differentiation of osteoblasts in the periosteum harvested from rats with intermittent injection of hPTH were observed in a short period of time in a culture system. We conclude that this type of periosteum can be used clinically for bone regenerative treatment as an autogeneous biomaterial.
It was previously reported that when hydroxyapatite (HAP) synthesized with an increased Ca/P molar ratio was heated to precipitate CaO on the HAP matrix, the HAP remained alkaline even when immersed in physiological saline. Alkaline HAP may cause cell toxicity, so heated HAP with a high molar ratio should be neutralized after being immersed in distilled water.
In this study, spherical HAP (average size of 35 μm) with a Ca/P molar ratio of 1.70 was prepared. The HAP samples were heated at 900℃ for 180 min. The heated HAP was soaked in distilled water for one week and the soak tests were repeated four times. The dissolution of Ca and pH value in distilled water were measured each week.
The X-ray diffraction pattern of HAP and the strength of fibronectin adsorption of 1.70-90 (HAP of molar ratio 1.70 heated at 900℃) and 1.70-90 W (HAP of molar ratio 1.70 heated at 900℃ and soaked four times) were measured, and the following results were obtained.
The pH value and the amount of dissolved Ca of 1.70-90 were highest, but they decreased as the frequency of soaked times increased. The results of X-ray diffraction analysis confirmed precipitated CaO on the surface of 1.70-90, but 1.70-90 W and other HAP were not confirmed. The pH of 1.70-90 W was 7.85. 1.70-90 W showed a higher strength of fibronectin adsorption than 1.70-90. The biological reaction will be researched in the future.
The purpose of this study was to create biomaterials from anatase-type titanium dioxide (TiO2). TiO2 is known for photocatalysis and osteogenesis. In order to apply this function to orthodontic brackets and coating materials for implants, the relationship between sintered temperature and cell proliferation was examined.
In addition, sintered temperature, crystal structure and the surface properties of sintering bodies were investigated.
Experimental Method: We began by pressure-molding anatase-type TiO2 powder and sintering it at temperatures of 700, 800, 900, 1,000, 1,100, 1,200 and 1,300℃ to produce sintered bodies for use as samples. We then used surface roughness, x-ray diffraction and scanning electron microscopy to observe the surface properties and texture. Moreover, we seeded the samples produced at each of the sintering temperatures with L929 mouse fibroblast cells in order to evaluate the cytocompatibility in terms of cell proliferation.
Results: For the samples sintered at 700℃, only the crystalline phase of anatase-type TiO2 was confirmed, but for the samples sintered at 800℃ or 900℃ the crystalline phase of anatase-type TiO2 and in some cases rutile-type TiO2 crystalline phases were confirmed. At sintering temperatures of 1,000℃ or higher, all samples were transformed into rutile-type TiO2.
In the test of cytocompatibility, the samples of anatase-type TiO2 sintered at 700℃ were found to have reduced cell counts after 24 to 96 hours of incubation compared to those immediately after being placed in the incubator (0 hour). However, the samples sintered at 800℃ or higher than 900℃ whereby the samples were transformed to rutile-type TiO2 showed remarkable cell proliferation even after time had passed.
The aim of this study was to evaluate the clinical retention force of implant magnetic dentures. Dental implants for a demonstration were implanted into a model of an edentulous jaw, and a maxillary roofless denture, on which a magnetic attachment was placed, was made. The magnetic attachments were placed at the positions corresponding to 17, 14, 12, 22, 24, and 27 in the FDI dental formula. Three types of magnetic attachment, i. e., flat-type, cushion-type and dome-type, were used. A tensile load was applied at one of two positions to remove the denture from the model: one was the center of both maxillary center incisors (front center), and the other was the barycenter of the positions of 6 magnetic attachments (barycenter). The effects of the locations of magnetic attachments, types of attachment, and positions of applying tensile load on the retention force were investigated, and the following conclusions were drawn.
1. The maximum retention force increased with the number of magnetic attachments, regardless of the tensile load application position, and the effect of the type of magnetic attachment in descending order was flat-type, cushion-type and dome-type.
2. The two-factor interaction between magnetic attachment location and type on retention force indicated that the difference among magnetic attachment types was small if the number of magnetic attachments was small, but the difference between the flat-type or the cushion-type and the dome-type became significantly large as the number of magnetic attachments increased. This tendency was more pronounced when the number of magnetic attachments was greater than four.
3. The two-factor interaction between magnetic attachment location and tensile load application position indicated that the retention force of the barycenter was greater than that of the front center in general, but the difference between the retention force of the two positions became significantly large as the number of magnetic attachments increased.
4. The two-factor interaction between the type of magnetic attachment and tensile load application position indicated that the retention force decreased in descending order of flat-type, cushion-type and dome-type, and the difference became large when the tensile load application position was the barycenter.
5. The retention force was strongly positively correlated with the area surrounded by magnetic attachments when the tensile load was applied to the barycenter, and increased with an increase of the area, although the correlation was poor when the tensile load application position was the front center.
Mandibular reconstruction using particulate cancellous bone and marrow (PCBM) is widely applied recently. Although titanium trays are the most popular material for this method, they have some disadvantages such as difficulty of making a suitable counter for a defect and the requirement of removal when dental implants are considered. Raw particulate hydroxylapatite/poly-L-lactide composite (HA/PLLA) is a resorbable material that has greater strength than pure PLLA and induces bone formation more rapidly.
We present the clinical course of implants in a case of reconstructed mandible using a custom-made HA/PLLA mesh tray with PCBM and platelet-rich plasma (PRP). We also evaluate the bone quality and structures of the reconstructed mandible around the implants.
The patient was a 66-year-old man who was diagnosed with a recurrent keratinized odontogenic tumor of the right molar region of the mandible. A mesh sheet type HA/PLLA was customized using the rapid prototyping method based on CT data. Resection of the tumor was carried out and PCBM was harvested from bilateral posterior iliac crests. PCBM and PRP were transferred to the tray, and the tray was rigidly fixed by HA/PLLA screws. Two dental implants were inserted in the molar area 10 months after the reconstruction with a two-stage procedure. The implants accomplished proper osseointegration, and successfully functioned without any abnormal symptom or bone resorption for 4 years of loading. Although the reconstructed bone showed a uniform structure immediately after reconstruction, CT evaluation clearly showed compact and cancellous bone structures 4 years after loading.
This case showed that the custom-made HA/PLLA tray system contributed to the implant treatment.
The aim of the present study was to evaluate the color and morphological changes of titanium dental implants after Er:YAG laser irradiation. Four different manufactured dental implants, ANKYLOS® with sand-blasted surface, Straumann®, CAMLOG® and SPI® with sandblasted and acid-etched surface, were exposed to Er:YAG laser irradiation with water spray at an energy density of 6.4～17.9 J/cm2. After Er:YAG laser irradiation, the surfaces of the implants were examined by stereomicroscope and scanning electron microscope. In the irradiated surface of each implant, brown discoloration after low energy density irradiation and blue discoloration after high energy density irradiation were observed. Melting of titanium was seen in the blue discolored area. Color alteration was detected at 6.4 J/cm2 on the surface of CAMLOG® or Straumann®, 8.5 J/cm2 on the surface of ANKYLOS®, and 13.5 J/cm2 on the surface of SPI®. Melting was observed at 12.4 J/cm2 on the surface of CAMLOG®, 13.5 J/cm2 on the surface of Straumann® or ANKYLOS®, and 17.9 J/cm2 on the surface of SPI®. The color and morphological changes occurred in the microstructured surface of the titanium implant with sand-blasted and acid etched surface with low energy density irradiation except SPI® products. These findings suggested that the surface changes of an implant induced by Er:YAG laser irradiation differed for each product, even in the case of implants with similar morphological surface.