Iron-labeled adipose stem cells and neovascularization in rabbit calvarial critical-sized defects.

OBJECTIVE: The aim of this study was to evaluate the presence of iron-labeled adipose stem cells at the 2-week time point and vascular changes at the 2-week and 6-week time points using two different types of scaffolds. STUDY DESIGN: This study included 22 White New Zealand adult male rabbits. In six rabbits, full-thickness calvarial critical-sized defects were filled with autogenous adipose stem cells labeled with iron oxide seeded onto two scaffolds, namely, solid bioactive glass (BAG) or porous tricalcium phosphate granules (TCP) used on reciprocal sides of the skull. Eleven rabbits were implanted with adipose stem cell-seeded scaffolds without iron labeling for analysis of vascular changes. Five defects were left empty as negative control defects. The specimens were analyzed histologically at the 2-week and 6-week time points. RESULTS: The TCP group showed significantly more vascularity compared with the BAG group. A greater number of labeled stem cells were identified in the TCP group compared with the BAG group, but the difference was not statistically significant. CONCLUSIONS: This study revealed the differences in stem cell distribution and revascularization of the calvarial defect, which may be biomaterial dependent.

Incidence of palatal fistula formation after primary palatoplasty in northern Finland.

OBJECTIVE: The purpose of this retrospective study was to determine the incidence of palatal fistulas after primary cleft palate repair. STUDY DESIGN: The study included 136 patients who were treated at the Oulu University Hospital cleft lip and palate center between 1998 and 2011. All patients were treated by the same surgeons with 1-stage palatoplasty closing the hard and soft palate concurrently. RESULTS: The overall frequency of postoperative fistula was 9.6% of patients. Patients with cleft lip and palate (20.0%) were more likely to develop postoperative palatal fistulas than patients with cleft palate (6.6%). Surgical technique and cleft severity were not significant factors for the development of palatal fistulas. CONCLUSIONS: The majority of patients undergoing primary palatal repair do not develop palatal fistulas.

Internal or in-scan validation: a method to assess CBCT and MSCT gray scales using a human cadaver.

OBJECTIVE: This study aimed to explore whether cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) can be used to quantify tissue density and to determine if the Hounsfield unit scale is applicable. STUDY DESIGN: A clinical MSCT scanner and effective energy adjusted photon beam attenuation references were used to compare the gray scale of CBCT images of the mandible region. A phantom was scanned using axial cadaver slices and 4 different homogeneous reference objects. The consistency of the references' gray values and 12 linear profile lines from both scanner data sets were compared. RESULTS: The gray values of the 2 scans showed strong correlation with quantified position-dependent differences as an outcome of the validation process. CONCLUSIONS: The introduced internal, in-scan validation is able to estimate and has a potential to compensate for the differences between MSCT and CBCT protocols. This validation serves as a guide in situations where the users can expect deviations.

Frequency of pharyngoplasty after primary repair of cleft palate in northern Finland.

OBJECTIVE: One measure of primary cleft palate repair success is the subsequent need for secondary pharyngoplasty due to velopharyngeal insufficiency. This study aimed to assess primary palatoplasty outcomes and frequency of secondary pharyngoplasty. STUDY DESIGN: A total of 138 patients underwent palatoplasty between 1998 and 2011. All patients were treated with 1-stage palatoplasty closing the hard and soft palate concurrently. RESULTS: Overall frequency of pharyngoplasty after palatoplasty was 21% of patients. The rate of secondary surgery was significantly higher for girls (27%) than for boys (13%). Patients with cleft lip and palate were more likely to require secondary pharyngoplasty (24%) than the patients with soft and hard cleft palate (20%). Surgical technique and cleft severity were significant factors for secondary surgery. Pharyngoplasty was least common in patients whose palatal clefts were treated at 9 to 12 months of age. CONCLUSIONS: The majority of patients undergoing primary palatal repair do not need secondary pharyngoplasty.

The biomechanical aspects of reconstruction for segmental defects of the mandible: a finite element study to assess the optimisation of plate and screw factors.

A bone plate is required to restore the load-bearing capacity of the mandible following a segmental resection. A good understanding of the underlying principles is crucial for developing a reliable reconstruction. A finite element analysis (FEA) technique has been developed to study the biomechanics of the clinical scenarios managed after surgical resection of a tumour or severe trauma to assist in choosing the optimal hardware elements. A computer aided design (CAD) model of an edentulous human mandible was created. Then 4 common segmental defects were simulated. A single reconstruction plate was designed to span the defects. The hardware variations studied were: monocortical or bicortical screw fixation and non-locking or locking plate design. A standardized load was applied to mimic the human bite. The von Mises stress and strain, spatial changes at the screw-bone interfaces were analysed. In general, the locking plate and monocortical screw fixation systems were most effective. Non-locking plating systems produced larger screw "pull-out" displacements, especially at the hemimandible (up to 5% strain). Three screws on either side of the defect were adequate for all scenarios except extensive unilateral defects when additional screws and an increased screw diameter are recommended. The simplification of screw geometry may underestimate stress levels and factors such as poor adaptation of the plate or reduced bone quality are likely to be indications for bicortical locking screw fixation. The current model provides a good basis for understanding the complex biomechanics and developing future refinements in plate or scaffold design.

Enzymes, dentinogenesis and dental caries: a literature review.

OBJECTIVES: Search in PubMed with keywords "enzymes, dentinogenesis, and dental caries" revealed only 4 items, but when combined with "enzymes, osteogenesis, and osteoporosis" as high as 404 items resulted. Dental caries was associated with an order of magnitude fewer studies than the chronic bone disease, osteoporosis. This observation motivated this review. MATERIAL AND METHODS: A comprehensive review of the available literature on role of enzymes in dentinogenesis and dental caries was undertaken using MEDLINE (PubMed) and Scopus. Keywords for the search were: enzymes and odontoblasts, enzymes and different forms of dentinogenesis as well as dental caries. RESULTS: Search revealed studies which described odontoblasts harbouring numerous enzymes (hydrolases, including metalloproteinases, transaminases and dehydrogenases) during primary dentinogenesis. Alkaline phosphatase activity sharply decreased when odontoblasts turned into quiescent odontoblasts. Tertiary dentinogenesis was characterized first by reactionary dentine formation when alkaline phosphatase was highly reactivated. Then later some of these odontoblasts may die out and be replaced by other progenitor cells of pulpal origin. This tertiary dentine was called reparative dentine. Pulpal progenitor/stem cells revealed alkaline phosphatase activity in areas encircling inflamed pulp sections. Soft carious dentine revealed high hydrolase, transaminase and dehyrogenase activities that may have originated from invading microbes, saliva or were endogenous. Proteolytic activity was especially demonstrable using histochemical and biochemical means. Specifically, matrix metalloproteases may have originated partly from activated proenzymes of host origin. CONCLUSIONS: Though dental studies are scanty when compared to bone, the active role of large spectrum of enzymes in healthy and carious dentine was given support.

Late reconstruction of orbital and naso-orbital deformities.

Acute orbital fractures and naso-orbital ethmoid fractures can result in chronic orbital and naso-orbital deformities. Understanding the acute injury is the first step in reconstructing the established late deformity. The best management strategy for reconstruction of orbital hypertelorism is to avoid late complications by repairing these deformities early near the time of the original fractures. New technologies from computer-guided surgical planning and additive manufacturing technology produce passive fitting implants tailored for patient-specific needs.

Exogenously added BMP-6, BMP-7 and VEGF may not enhance the osteogenic differentiation of human adipose stem cells.

In the present study bone morphogenetic protein (BMP)-6 alone or in synergy with BMP-7 and vascular endothelial growth factor (VEGF) were tested with human adipose stem cells (hASCs) seeded on cell culture plastic or 3D bioactive glass. Osteogenic medium (OM) was used as a positive control for osteogenic differentiation. The same growth factor groups were also tested combined with OM. None of the growth factor treatments could enhance the osteogenic differentiation of hASCs in 3D- or 2D-culture compared to control or OM. In 3D-culture OM promoted significantly total collagen production, whereas in 2D-culture OM induced high total ALP activity and mineralization compared to control and growth factors groups, but also high cell proliferation. In this study, hASCs did not respond to exogenously added growth although various parameters of the study set-up may have affected these findings contradictory to the previous literature.

A finite element analysis of bone plates available for prophylactic internal fixation of the radial osteocutaneous donor site using the sheep tibia model.

INTRODUCTION: The strengthening effect of prophylactic internal fixation (PIF) with a bone plate at the radial osteocutaneous flap donor site has previously been demonstrated using the sheep tibia model of the human radius. This study investigated whether a finite element (FE) model could accurately represent this biomechanical model and whether stress or strain based failure criteria are most appropriate. METHODS: An FE model of an osteotomised sheep tibia bone was strengthened using 4 types of plates with unilocking or bicortical screw fixation. Torsion and 4-point bending simulations were performed. The maximum von Mises stresses and strain failure criteria were studied. RESULTS: The strengthening effects when applying stress failure criteria [factor 1.76-4.57 bending and 1.33-1.80 torsion] were comparable to the sheep biomechanical model [factor 1.73-2.43 bending and 1.54-2.63 torsion]. The strongest construct was the straight 3.5mm stainless steel unilocking plate. Applying strain criteria the strongest construct was the straight 3.5mm stainless DCP plate with bicortical screw fixation. CONCLUSIONS: The FE model was validated by comparison with the sheep tibia model. The complex biomechanics at the bone-screw interface require further investigation. This FE modelling technique may be applied to a model of the human radius and other sites.

Refinements in osteotomy design to improve structural integrity: a finite element analysis study.

Osteotomy cuts are typically made using a saw, and the meeting point acts as a focus for the concentration of stress and failure. We have studied the impact of different designs of osteotomy cut. Cadaver sheep tibias were scanned by computed tomography (CT) and transformed into a computer-aided design (CAD) model. A standard marginal resection defect was created and then modified, and a finite element analysis made. The relative stress concentrations at the intersection of osteotomy cuts were recorded using principal stresses S1, S3, and von Mises stress, von Mises under both 4-point bending and torsion testing. The osteotomy designs studied were: right-angled and bevelled osteotomy end cuts, overcutting, and a stop drill hole. Peak stress values for 4-point bending and torsion were 24-30% greater at the right-angled osteotomy than the bevelled end cut. Overcutting dramatically increased peak stress values caused by bending and torsion by 48% and 71%, respectively. Substantially lower concentrations of stress were noted with a stop hole using both a 90° (bending 38% and torsion 56%), and a tangential (bending 58% and torsion 60%) cut. A bevelled osteotomy has substantially lower concentrations of stress than a right-angled osteotomy. It is important to avoid creating an overcut as this causes an appreciable increase in the concentration of stress, while a stop drill hole substantially reduces the stress. The creation of a stop hole and the use of judicious bevelling techniques are modifications in the design of an osteotomy that are readily applicable to surgical practice.

Tissue engineering of bone: Clinical observations with adipose-derived stem cells, resorbable scaffolds, and growth factors.

INTRODUCTION: Tissue engineering offers a simple, nonallergenic, and viable solution for the reconstruction of human tissues such as bone. With deeper understanding of the stem cell's pathobiology, the unique properties of these tissues can be effectively harnessed for the benefit of the patients. A primary source of mesenchymal stem cells (MSCs) for bone regeneration is from adipose tissue to provide adipose-derived stem cells (ASCs). The interdependency between adipogenesis and osteogenesis has been well established. The objective of this article is to present the preliminary clinical observation with reconstruction of craniofacial osseous defects larger than critical size with ASC. MATERIALS AND METHODS: Patients with large craniofacial osseous defects only were included in this study. Autogenous fat from the anterior abdominal wall of the patients was harvested from 23 patients, taken to a central tissue banking laboratory and prepared. All patients were reconstructed with ASCs, resorbable scaffolds, and growth factor as required. Vascularized soft tissue beds were prepared for ectopic bone formation and later microvascular translocation as indicated. RESULTS: 23 ASC seeded resorbable scaffolds have been combined with rhBMP-2 and successfully implanted into humans to reconstruct their jaws except for three failures. The failures included one infection and two cases of inadequate bone formation. DISCUSSION: The technique of ASC-aided reconstruction of large defects still remains extremely sensitive as it takes longer duration and is costlier than the conventional standard immediate reconstruction. Preliminary results and clinical observations of these cases are extremely encouraging. In future, probably with evolving technological advances, ASC-aided reconstruction will be regularly used in clinical practise.

Beta-tricalcium phosphate/type I collagen cones with or without a barrier membrane in human extraction socket healing: clinical, histologic, histomorphometric, and immunohistochemical evaluation.

The aim of this study was to investigate the healing of human extraction sockets filled with ß-tricalcium phosphate and type I collagen (ß-TCP/Clg) cones with or without a barrier membrane. Twenty patients were divided in two groups: (A) ß-TCP/Clg non-membrane and (B) ß-TCP/Clg + barrier membrane. Clinical examination and biopsies from the grafted sites were collected 9 months later. Bone samples were analyzed using histomorphometry and immunohistochemistry. The horizontal dimension of the alveolar ridge was significantly reduced 9 months after socket preservation in the non-membrane group. There was bone formation with no significant differences between the two groups in the areas occupied by new bone (A = 42.4%; B = 45.3%), marrow (A = 42.7%; B = 35.7%), or residual graft (A = 9.7%; B = 12.5%). Immunohistochemistry revealed osteonectin expression in both groups. Both groups demonstrated sufficient amounts of vital bone and socket morphology to support dental implant placement after the 9-month healing period. A future trial to evaluate the alveolar outcomes at an earlier 6-month time point rather than the 9 months used in this study would be of interest.

Bimaxillary advancement as the initial treatment of obstructive sleep apnea: five years follow-up of the pori experience.

OBJECTIVES: Bimaxillary advancement surgery has proven to be effective treatment of obstructive sleep apnea syndrome. According to the Stanford protocol upper airway soft tissue surgery or advancement of tongue by chin plastic surgery is first carried out and if obstructive sleep apnea persists, then bimaxillary advancement is done. This study describes the 5 year outcome of 13 obstructive sleep apnea patients in whom the Stanford protocol was omitted and bimaxillary advancement was carried out as initial surgical treatment. MATERIAL AND METHODS: Patients were divided in two groups. Group A comprised patients with obstructive sleep apnea (OSAS) confirmed by polysomnography in whom ODI-4 (oxygen desaturation index) was 5 or more. Group B consisted of patients with occlusal problems needing orthognathic surgery and with OSAS symptoms but no clear disease on polysomnography, where the ODI-4 index was less than 5. Both groups were treated with bimaxillary advancement surgery (BAS) as initial therapy. RESULTS: In the group A mean ODI-4 was 17.8 (SD 12) before treatment and 3.5 (SD 3.4) at 5-year follow-up (P = 0.018 in paired differences t-test). In group B the ODI-4 remained below 5. In group A mean saturation improved from 94.3% (SD 1.6) to 96.3% (SD 2), P = 0.115 and in group B from 96.3% (SD 1.2) to 97.8% (SD 1.7), P = 0.056 (in paired differences t-test). The static charge sensitive bed evaluation showed improvement in all patients except one. CONCLUSIONS: Bimaxillary advancement surgery is safe and reliable as an initial surgical treatment of obstructive sleep apnea syndrome.

Osteoinductivity of partially purified bovine, ostrich and emu bone morphogenetic proteins in vitro.

The aim of this study was to observe the osteogenic activity of native bone morphogenetic proteins (BMPs) obtained from different species including bovine, ostrich and emu sources in order to compare mammalian and avian BMPs. Rat mesenchymal progenitor marrow stromal cells and pre-osteoblastic C2C12 cell cultures, were exposed to the native BMPs and alkaline phosphatase (ALP) and creatine kinase (CK) levels were determined by assay. The results showed that the ALP activity in C2C12 cultures was elevated by bovine BMP by 2- to 10-fold (p < 0.05-0.001) from day 3 during 14 days. There were no significant differences in avian BMP related elevations of ALP activity except with ostrich BMPs at day 14 (p < 0.05). However, exposure of MSCs cultures to BMPs derived from bovine, ostrich or emu sources resulted in elevated ALP from day 3 (p < 0.05). Bovine BMP resulted in more ALP elevation than with either of the avian BMPs. All of BMPs elevated Creatine kinase (CK) activity from day 1 and climbed until peaking at day 7. Compared with control cultures, CK was elevated more with exposure to emu BMP and was more elevated with greater statistical significance than with bovine and ostrich BMP before day 5. These higher levels remained until day 14 (p < 0.05). The results of this study suggest that both bovine and avian BMPs are able to stimulate osteogenesis in mature osteoblasts in vitro. The strongest synergistic effect on osteogenesis was detected in cells stimulated with bovine BMP. Avian BMPs had lower effects on ALP and CK activity, emu BMP being more effective than ostrich BMP.

The effects of vibration loading on adipose stem cell number, viability and differentiation towards bone-forming cells.

Mechanical stimulation is an essential factor affecting the metabolism of bone cells and their precursors. We hypothesized that vibration loading would stimulate differentiation of human adipose stem cells (hASCs) towards bone-forming cells and simultaneously inhibit differentiation towards fat tissue. We developed a vibration-loading device that produces 3g peak acceleration at frequencies of 50 and 100 Hz to cells cultured on well plates. hASCs were cultured using either basal medium (BM), osteogenic medium (OM) or adipogenic medium (AM), and subjected to vibration loading for 3 h d(-1) for 1, 7 and 14 day. Osteogenesis, i.e. differentiation of hASCs towards bone-forming cells, was analysed using markers such as alkaline phosphatase (ALP) activity, collagen production and mineralization. Both 50 and 100 Hz vibration frequencies induced significantly increased ALP activity and collagen production of hASCs compared with the static control at 14 day in OM. A similar trend was detected for mineralization, but the increase was not statistically significant. Furthermore, vibration loading inhibited adipocyte differentiation of hASCs. Vibration did not affect cell number or viability. These findings suggest that osteogenic culture conditions amplify the stimulatory effect of vibration loading on differentiation of hASCs towards bone-forming cells.

Bisphosphonate-associated osteonecrosis of the jaw in Ontario: a survey of oral and maxillofacial surgeons.

OBJECTIVE: Osteonecrosis of the jaw (ONJ) in association with use of bisphosphonate (BP) has been described primarily in cancer patients receiving high-dose intravenous BP. The frequency of the condition in patients with osteoporosis appears to be low. We evaluated the frequency of BP-associated ONJ in Ontario in the cancer population and in those receiving BP for osteoporosis and metabolic bone disease. METHODS: A survey developed by representatives of the Ontario Society of Oral and Maxillofacial Surgeons was mailed to Ontario oral and maxillofacial surgeons (OMFS) in December 2006, asking oral surgeons to provide information on cases of ONJ seen in the previous 3 calendar years (2004 to 2006). OMFS were subsequently contacted by telephone if they had not responded or if they had reported cases of ONJ. The frequency of ONJ in association with BP use was estimated from the number of patients with filled prescriptions for BP in Ontario between 2004 and 2006. The cumulative incidence of ONJ was calculated separately for patients using intravenous (IV) BP for cancer treatment and for patients using oral or IV BP for osteoporosis or other metabolic bone disease. RESULTS: Between 2004 and 2006, 32 ONJ cases were identified. Nineteen patients received IV BP for cancer treatment and 13 patients received oral or IV BP for osteoporosis or metabolic bone disease. Over a 3-year period the cumulative incidence of BP-associated ONJ was 0.442% of cancer patient observations (442 per 100,000) and 0.001% of osteoporosis or other metabolic bone disease observations (1.04 per 100,000). The relative risk of low dose IV/oral BP-associated ONJ was 0.002 (95% CI 0.001, 0.005) compared to high-dose IV BP. Other risk factors for ONJ were present in all cases in whom detailed assessment was available. The median duration of exposure to BP was 42 months (range 36 to 120 mo) and 42 months (range 11 to 79 mo) in osteoporosis patients and cancer patients, respectively. CONCLUSION: Over a 3-year period, the cumulative incidence for BP-associated ONJ was 0.442% of cancer patient observations (442 per 100,000) and 0.001% of osteoporosis or metabolic bone disease observations (1.04 per 100,000). This study provides an approximate frequency of BP-associated ONJ in Canada. These data need to be quantified prospectively with accurate assessment of coexisting risk factors.

Posterior cranial vault distraction osteogenesis in craniosynostosis: estimated increases in intracranial volume.

PURPOSE: To study distraction osteogenesis of the posterior cranial vault in children requiring increased intracranial volume. MATERIALS AND METHODS: Ten patients were treated with cranial distractors. Five children had previously been operated for scaphocephaly and one child for Saether-Chotzen syndrome. Two patients had bilateral coronal suture synostosis with Muenke syndrome and two patients had Apert syndrome. At surgery, the cranial bones were mobilized, the head was widened during surgery, and the segments fixed to each other with distractors. Further expansion at a rate of 1 mm/day was performed over 2-4 weeks. The cranium was distracted posteriorly from 20 to 30 mm. RESULTS: The patients all tolerated surgery and distraction well. In all cases, the parents were able to perform the distraction at home. There were no technical problems with the distraction devices. Two cases had minor cutaneous problems, where the distractor penetrated the skin. These cases responded to gentle local wound care measures. At the time of distractor removal, ossification had occurred sufficiently in one of these two cases. In the other case, the device was removed and replaced with a resorbable plate, without any harmful effect on the result. In all cases, sufficient expansion was achieved without causing more cosmetic deformity. Ossification occurred in all cases. This method seems effective, as the calculated increase in intracranial volume was a mean of 20.2% (range 10.2-28.5%). CONCLUSIONS: This preliminary series shows that cranial bone distraction is a useful method for cranial expansion with low morbidity in children with craniosynostosis.

Augmentation of the maxillary sinus: comparison of bioimplants containing bone morphogenetic protein and autogenous bone in a rabbit model.

OBJECTIVE: To evaluate the effectiveness of various bioimplants used for augmentation of the maxillary sinus floor by means of a rabbit model. MATERIALS AND METHODS: Bone was harvested from the posterior iliac crest of 40 adult New Zealand white rabbits to allow bilateral augmentation of the floor of the maxillary sinus with autogenous bone or other materials. One of the following was grafted to the maxillary sinus of each rabbit: particulated autogenous bone, demineralized bone matrix (DBM), DBM combined with purified bone morphogenetic protein (BMP-DBM bioimplants) and bioimplants consisting of a poloxamer gel with BMP in 1 of 2 different doses. Animals were sacrificed at 2 or 8 weeks. Histologic examination was used to assess biologic healing in the various samples. Histomorphometry was used to demonstrate and quantify bone formation. RESULTS: After 2 weeks, the BMP-containing bioimplants had produced more new bone than any of the other materials. Particulated autogenous bone grafts produced less new bone initially (after 2 weeks), but the amount of bone produced by these grafts gradually increased, to levels comparable to the BMP-containing bioimplants by 8 weeks. For groups in which the poloxamer gel was used as a carrier for BMP or where BMP was used in combination with DBM, the amount of bone generated by 8 weeks was similar to that produced by autogenous bone. CONCLUSION: The rabbit maxillary sinus model allowed evaluation of multiple types of bioimplants that could be suitable for peri-implant maxillary reconstruction. BMP-containing bioimplants demonstrated promise as alternatives to autogenous bone grafts for sinus-augmentation procedures. These bioimplants had more rapid initial bone production than all other materials, including autogenous bone. In the future, such biomaterials may enable earlier placement of dental implants into augmented maxillary sinuses.

The expression of bone matrix proteins induced by different bioimplants in a rabbit sinus lift model.

This study aimed to analyze the expression of bone matrix proteins and CD31 by immunohistochemistry after maxillary sinus grafting with different bioimplants in a rabbit model. Rabbit demineralized bone matrix (DBM), partially purified bovine bone morphogenetic proteins (BMP), a mixture of BMP with DBM (BMP/DBM), or particulated autogenous bone was grafted into the maxillary sinuses of 42 rabbits. Animals were sacrificed at 2 and 8 weeks. Immunohistochemistry was used to investigate the expression of type 1 collagen (COL1), osteonectin (ON), osteocalcin (OC), bone sialoprotein (BSP), osteopontin (OPN), and CD31. Sinuses grafted with BMP were filled with trabeculae of woven bone that was strongly immunoreactive for COL1, OC, ON, and BSP. BMP/DBM showed strongly positive immunoreactivity for these proteins within the newly formed bone, but weak immunoreactivity in the DBM particles. Immunoreactivity for COL1, OC, ON, and BSP in DBM sinuses was only seen in the osteoblasts rimming the grafted bone particles. The staining of autogenous bone graft sinuses was similar to those grafted with DBM. OPN staining was detected in autogenous bone graft, BMP/DBM, and BMP bioimplants. CD31 staining was strongest in BMP and BMP/noncollagenous matrix proteins sinuses. These results suggest that exogenous BMP enhances not only osteogenesis but also angiogenesis, an important part of bone repair.

Vitamin D(3) metabolites induce osteogenic differentiation in human dental pulp and human dental follicle cells.

Vitamin D(3) metabolites regulate the bone metabolism and 1α,25-dihydroxyvitamin D(3) (1α,25(OH)(2)D(3)) is known to play an important role in teeth mineralization. However, little is known about the potential of vitamin D as an osteogenic inducer in human dental pulp (hDPCs) and dental follicle cells (hDFCs) in vitro. Therefore, we investigated the effects of vitamin D(3) metabolites 1α,25(OH)(2)D(3) and 25-hydroxyvitamin D(3) (25OHD(3)) on proliferation and osteogenic differentiation of hDPCs and hDFCs in vitro. We also examined whether vitamin D(3) metabolic enzymes were regulated in hDFCs and hDPCs. Cell proliferation was decreased by both metabolites in hDPCs and hDFCs. Vitamin D(3) metabolites increased ALP activity and induced mineralization when osteogenic supplements (OS; l-ascorbic acid-2-phosphate+ß-glycerophosphate) were added, though the expression of osteocalcin (OC) and osteopontin (OPN) were regulated without the addition of OS. CYP24 and CYP27B1 expressions were upregulated by vitamin D(3) metabolites and 25OHD(3) was converted into 1α,25(OH)(2)D(3) in the culture medium. These results confirm that 1α,25(OH)(2)D(3) (10 and 100 nM) and 25OHD(3) (500 nM) can be used as osteogenic inducers synergistically with osteogenic supplements for differentiation of hDPCs and hDFCs. Furthermore, our findings strengthen our knowledge about the role of hDPCs and hDFCs as vitamin D(3) target cells.