Low-level laser therapy affects osseointegration in titanium implants: resonance frequency, removal torque, and histomorphometric analysis in rabbits.

OBJECTIVES: The purpose of this study was to investigate the effects of low-level laser therapy (LLLT) with a diode gallium-aluminum-arsenide (Ga-Al-As) low-level laser device on the healing and attachment of titanium implants in bone. MATERIALS AND METHODS: Thirteen New Zealand white male rabbits weighing 3.0±0.5 kg were used for this study. Dental titanium implants (3.75 mm in diameter and 8.5 mm in length, US II RBM plus fixture; Osstem, Seoul, Korea) were implanted into both femurs of each rabbit. The rabbits were randomly divided into a LLLT group and a control group. The LLLT was initiated immediately after surgery and then repeated daily for 7 consecutive days in the LLLT group. Six weeks and 12 weeks after implantation, we evaluated and compared the osseointegration of the LLLT group and control group, using histomorphometric analysis, removal torque testing, and resonance frequency analysis (RFA). The results were statistically significant when the level of probability was 0.05 or less based on a non-parametric Mann-Whitney U-test. RESULTS: The implant survival rate was about 96%. Histologically and histomorphometrically, we observed that the titanium implants were more strongly attached in LLLT group than in control group. However, there was no significant difference between the LLLT group and control group in removal torque or RFA. CONCLUSION: Histologically, LLLT might promote cell-level osseointegration of titanium implants, but there was no statistically significant effects.

Stability of Le Fort I Osteotomy With Propeller Graft for Canting Correction in Facial Asymmetry.

The aim of this study was to evaluate the maxillary stability in patients who had undergone Le Fort I osteotomy with propeller graft and mandibular sagittal split ramus osteotomy for correction of maxillary asymmetry. This was a retrospective study on 15 facial asymmetry patients (7 men, 8 women: 22.2 years) requiring surgical correction at the preoperative (T0), immediately postoperative (T1) and 6 months after surgery (T2) stages. To evaluate the skeletal stability, computed tomography (CT) superimposition was used, and skeletal landmarks were measured and compared from the superimposed images according to an x, y, z coordinate system. The skeletal changes at each stage (ΔT1-T0 and ΔT2-T1) were compared by paired t-test (P<0.05). The obtained data on the skeletal changes immediately postoperatively to 6-month follow-up (ΔT2-T1) showed that the Le Fort I osteotomy with propeller graft had effected stable maxillary skeletal stability at the maxillary measurement points (posterior nasal spine (PNS ), nasopalatine canal, U3 crown tip, U3 root apex, and U6 furcation). These results suggested that in cases of facial asymmetry where the upper tooth exposure is proper and anterior-posterior movement of the maxilla is not much required, Le Fort I osteotomy with propeller graft is an effective method for stable canting correction.

Stability of unilateral sagittal split ramus osteotomy for correction of facial asymmetry: long-term case series and literature review.

Bilateral sagittal split ramus osteotomy is considered a standard technique in mandibular orthognathic surgeries to reduce unexpected bilateral stress in the temporomandibular joints. Unilateral sagittal split ramus osteotomy (USSO) was recently introduced to correct facial asymmetry caused by asymmetric mandibular prognathism and has shown favorable outcomes. If unilateral surgery could guarantee long-term postoperative stability as well as favorable results, operation time and the incidence of postoperative complications could be reduced compared to those in bilateral surgery. This report highlights three consecutive cases with long-term follow-up in which USSO was used to correct asymmetric mandibular prognathism. Long-term postoperative changes in the condylar contour and ramus and condylar head length were analyzed using routine radiography and computed tomography. In addition, prior USSO studies were reviewed to outline clear criteria for applying this technique. In conclusion, patients showing functional-type asymmetry with predicted unilateral mandibular movement of less than 7 mm can be considered suitable candidates for USSO-based correction of asymmetric mandibular prognathism with or without maxillary arch surgeries.

Human umbilical cord blood-derived CD34-positive endothelial progenitor cells stimulate osteoblastic differentiation of cultured human periosteal-derived osteoblasts.

The aim of this study was to examine the effects of human umbilical cord blood-derived CD34-positive endothelial progenitor cells (CD34+ EPCs) on osteoblastic differentiation of cultured human periosteal-derived osteoblasts (POs). CD34+ cells from human umbilical cord blood were sorted to purify more EPCs in characterization. These sorted cells showed CD31, VE-cadherin, and KDR expression as well as CD34 expression and formed typical tubes in Matrigel. These sorted cells were referred to as human cord blood-derived CD34+ EPCs. In in vivo bone formation using a miniature pig model, the newly formed bone was clearly examined in defects filled with polydioxanone/pluronic F127 (PDO/Pluronic F127) scaffolds containing either human umbilical cord blood-derived CD34+ EPCs and POs or human umbilical vein endothelial cells (HUVEC) and POs; however, the new bone had the greatest density in the defect treated with CD34+ EPCs and POs. Osteoblastic phenotypes of cultured human POs using ALP activity and von Kossa staining were also more clearly found in CD34+ EPC-conditioned medium than CD34-negative (CD34-) cell-conditioned medium, whereas HUVEC-conditioned medium had an intermediate effect. PCR array for common cytokines and growth factors showed that the secretion of interleukin (IL)-1ß was significantly higher in CD34+ EPCs than in HUVEC, followed by level in CD34- cells. In addition, IL-1ß also potently and dose dependently increased ALP activity and mineralization of POs in culture. These results suggest that human umbilical cord blood-derived CD34+ EPCs stimulates osteoblastic differentiation of cultured human POs. The functional role of human umbilical cord blood-derived CD34+ EPCs in increasing the osteogenic phenotypes of cultured human POs may depend on IL-1ß secreted from human umbilical cord blood-derived CD34+ EPCs.

JNK signaling plays an important role in the effects of TNF-α and IL-1ß on in vitro osteoblastic differentiation of cultured human periosteal-derived cells.

The purpose of this study was to examine the effects of TNF-α and IL-1ß on in vitro osteoblastic differentiation of cultured human periosteal-derived cells. To examine the effects of TNF-α and IL-1ß on in vitro osteoblastic differentiation of cultured human periosteal-derived cells, the cells cultured in the osteogenic induction medium were treated with 0.1-10 ng/ml TNF-α and 0.01-1 ng/ml IL-1ß. TNF-α and IL-1ß enhanced the alkaline phosphatase (ALP) activity and alizarin red S staining in cultured human periosteal-derived cells. However, these cytokines did not stimulate the Runt-related transcription factor (Runx) 2 activity and osteocalcin secretion. The ALP activity was decreased in the periosteal-derived cells pretreated with mitogen activated protein kinase (MAPK) inhibitors and then treated with TNF-α or IL-1ß. Among the periosteal-derived cells pretreated with MAPK inhibitors, the ALP activity was markedly decreased in the cells pretreated with SP 600125, the specific inhibitor of C-Jun N-terminal kinase (JNK). The periosteal-derived cells treated with TNF-α and IL-1ß showed an increase in extracellular signal-regulated kinase (ERK) and JNK phosphorylation. Among the ERK and JNK phosphorylation, JNK phosphorylation was strongly observed in the cells. These results suggest that TNF-α and IL-1ß increased the in vitro osteoblastic differentiation of cultured human periosteal-derived cells by enhancing the ALP activity and mineralization process, but not by Runx2 activation. The functional role of TNF-α and IL-1ß in increasing the ALP activity and mineralization of periosteal-derived cells primarily depends on the JNK signaling among the MAPK pathways.

Generation of osteogenic construct using periosteal-derived osteoblasts and polydioxanone/pluronic F127 scaffold with periosteal-derived CD146 positive endothelial-like cells.

The purpose of this study was to generate tissue-engineered bone using human periosteal-derived osteoblasts (PO) and polydioxanone/pluronic F127 (PDO/pluronic F127) scaffold with preseeded human periosteal-derived CD146 positive endothelial-like cells (PE). PE were purified from the periosteal cell population by cell sorting. One of the important factors to consider in generating tissue-engineered bone using osteoprecursor and endothelial cells and a specific scaffold is whether the function of osteoprecursor and endothelial cells can be maintained in originally different culture medium conditions. After human PE were preseeded into PDO/pluronic F127 scaffold and cultured in endothelial cell basal medium-2 for 7 days, human PO were seeded into the PDO/pluronic F127 scaffold with PE, and then, this cell-scaffold construct was cultured in endothelial cell basal medium-2 with osteogenic induction factors, including ascorbic acid, dexamethasone, and ß-glycerophosphate, for a further 7 days. Then, this 2-week cultured construct was grafted into the mandibular defect of miniature pig. Twelve weeks after implantation, the animal was sacrificed. Clinical examination revealed that newly formed bone was seen more clearly in the defect with human PO and PDO/pluronic F127 scaffold with preseeded human PE. The experimental results suggest that tissue-engineered bone formation using human PO and PDO/pluronic F127 scaffold with preseeded human PE can be used to restore skeletal integrity to various bony defects when used in clinics.

Tissue-engineered bone formation using periosteal-derived cells and polydioxanone/pluronic F127 scaffold with pre-seeded adipose tissue-derived CD146 positive endothelial-like cells.

The aim of this study was to generate tissue-engineered bone formation using periosteal-derived cells seeded into a polydioxanone/pluronic F127 (PDO/Pluronic F127) scaffold with adipose tissue-derived CD146 positive endothelial-like cells. Considering the hematopoietic and mesenchymal phenotypes of adipose tissue-derived cells cultured in EBM-2 medium, CD146 positive adipose tissue-derived cells was sorted to purify more endothelial cells in characterization. These sorted cells were referred to as adipose tissue-derived CD146 positive endothelial-like cells. Periosteum is a good source of osteogenic cells for tissue-engineered bone formation. Periosteal-derived cells were found to have good osteogenic capacity in a PDO/Pluronic F127 scaffold, which could provide a suitable environment for the osteoblastic differentiation of these cells. Through the investigation of capillary-like tube formation on matrigel and the cellular proliferation of adipose tissue-derived CD146 positive endothelial-like cells cultured in different media conditions, we examined these cells could be cultured in EBM-2 with osteogenic induction factors. We also observed that the osteogenic activity of periosteal-derived cells could be good in EBM-2 with osteogenic induction factors, in the early period of culture. The experimental results obtained in the miniature pig model suggest that tissue-engineered bone formation using periosteal-derived cells and PDO/Pluronic F127 scaffold with pre-seeded adipose tissue-derived CD146 positive endothelial-like cells can be used to restore the bony defects of the maxillofacial region when used in clinics.

Vascular endothelial growth factor stimulates osteoblastic differentiation of cultured human periosteal-derived cells expressing vascular endothelial growth factor receptors.

Angiogenesis plays an important role in bone development and postnatal bone fracture repair. Vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptors (VEGFRs) are primarily involved in angiogenesis. This study investigated the expression of VEGF isoforms, VEGFR-1, and VEGFR-2 during the osteoblastic differentiation of cultured human periosteal-derived cells. In addition, the effect of exogenous VEGF on the osteoblastic differentiation of cultured human periosteal-derived cells was also examined. The expression of the VEGF isoforms (VEGF(121), VEGF(165), VEGF(189), and VEGF(206)), VEGFR-1, and VEGFR-2 was observed in the periosteal-derived cells. Administration of KRN633, a VEGFR-1 and VEGFR-2 inhibitor, decreased the alkaline phosphatase (ALP) activity during the osteoblastic differentiation of cultured human periosteal-derived cells. However, the administration of VEGFR2 Kinase Inhibitor IV, a VEGFR-2 inhibitor, did not affect the ALP activity. The addition of recombinant human VEGF(165) elevated the ALP activity and increased the calcium content in the periosteal-derived cells. Treating the periosteal-derived cells with recombinant human VEGF(165) resulted in an increase in Runx2 transactivation in the periosteal-derived cells. These results suggest that exogenous VEGF stimulates the osteoblastic differentiation of cultured human periosteal-derived cells and VEGF might act as an autocrine growth factor for the osteoblastic differentiation of cultured human periosteal-derived cells.

Osteogenic differentiation of human periosteal-derived cells in a three-dimensional collagen scaffold.

This study examined the osteogenic differentiation of cultured human periosteal-derived cells grown in a three dimensional collagen-based scaffold. Periosteal explants with the appropriate dimensions were harvested from the mandible during surgical extraction of lower impacted third molar. Periosteal-derived cells were introduced into cell culture. After passage 3, the cells were divided into two groups and cultured for 28 days. In one group, the cells were cultured in two-dimensional culture dishes with osteogenic inductive medium containing dexamethasone, ascorbic acid, and ß-glycerophosphate. In the other group, the cells were seeded onto a three-dimensional collagen scaffold and cultured under the same conditions. We examined the bioactivity of alkaline phosphatase (ALP), the RT-PCR analysis for ALP and osteocalcin, and measurements of the calcium content in the periosteal-derived cells of two groups. Periosteal-derived cells were successfully differentiated into osteoblasts in the collagen-based scaffold. The ALP activity in the periosteal-derived cells was appreciably higher in the three-dimensional collagen scaffolds than in the two-dimensional culture dishes. The levels of ALP and osteocalcin mRNA in the periosteal-derived cells was also higher in the three-dimensional collagen scaffolds than in the two-dimensional culture dishes. The calcium level in the periosteal-derived cells seeded onto three-dimensional collagen scaffolds showed a 5.92-fold increase on day 7, 3.28-fold increase on day 14, 4.15-fold increase on day 21, and 2.91-fold increase on day 28, respectively, compared with that observed in two-dimensional culture dishes. These results suggest that periosteal-derived cells have good osteogenic capacity in a three-dimensional collagen scaffold, which provides a suitable environment for the osteoblastic differentiation of these cells.

Three-dimensional analysis of midfacial soft tissue changes according to maxillary superior movement after horizontal osteotomy of the maxilla.

Three-dimensional diagnostic and treatment planning is a promising means of improving orthognathic surgical results from the standpoint of facial aesthetics. In such planning, cone-beam computed tomography is a useful tool. The purpose of the present study was to evaluate three-dimensional soft tissue changes in the midfacial region, with specific reference to post-Le Fort I osteotomy maxillary superior movement. Twenty-two patients underwent both Le Fort I osteotomy superior impaction and bilateral sagittal split ramus osteotomy of the mandible (ie, double-jaw surgery). Reference planes and 27 × 10 grids were used in evaluating the midfacial soft tissue areas. The extent of soft tissue change before and after surgery was calculated and analyzed. The results showed no statistical difference between the male and female subjects (P > 0.05). For both the male and the female patients after double-jaw surgery, the soft tissue in the triangular area, which includes both the nasolabial grooves and the upper lip, moved in the anterior direction and maxillary superiorly. It is essential that clinicians concerned about the management of soft tissue and the quality of treatment outcomes understand the pattern of soft tissue change after double-jaw surgery.

In vitro osteogenic differentiation of cultured human dental papilla-derived cells.

PURPOSE: This study examined the osteogenic phenotypes and mineralization of cultured human dental papilla-derived cells. MATERIALS AND METHODS: Dental papillae were harvested from mandibles during surgical extraction of lower impacted third molars from 3 patients aged 13 to 15 years. The dental papilla-derived cells were introduced into the cell culture. After passage 3, the dental papilla-derived cells were further cultured for 42 days in an osteogenic inductive culture medium containing dexamethasone, ascorbic acid, and beta-glycerophosphate. We examined the histochemical detection of alkaline phosphatase (ALP), the reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for ALP and osteocalcin, and von Kossa staining in the dental papilla-derived cells. RESULTS: It was observed that ALP was strongly expressed in the earlier stage of osteoblastic differentiation, whereas osteocalcin was mainly expressed and secreted into the medium at the later stage. Von Kossa-positive mineralization nodules were first observed on day 14, which increased in number during the entire culture period. CONCLUSIONS: These results suggest that dental papilla-derived cell have osteogenic potential and could be used as an additional source of cells for bone tissue engineering.

Expression of receptor activator of nuclear factor -kappaB ligand, receptor activator of nuclear factor -kappaB, and osteoprotegerin, following low-level laser treatment on deproteinized bovine bone graft in rats.

The aim of this study was to investigate by immunohistochemistry the effects of low-level laser (LLL) irradiation on the expression of the receptor activator of nuclear factor -kappaB ligand (RANKL), osteoprotegerin (OPG), and the receptor activator of nuclear factor -kappaB (RANK) in deproteinized bovine bone grafts in rats. Twenty-four male Sprague-Dawley rats aged 15 weeks were allocated to either an experimental group that underwent LLL irradiation during bone healing at the bone graft sites of the rats' calvarial bone defects or a control group. In the experimental group, gallium-aluminum-arsenide (Ga-Al-As) diode LLL (wavelength 808 nm; output 96 mW) was used to irradiate three areas on and around bone defects. The radiation was administered by the contact method for 10 s at 8.3 J/cm(2), once a day for 7 days. The total dose over the complete schedule was 40.32 J. The animals were killed on days 7, 14 or 21. The results of immunohistochemical analysis showed that the expression of RANKL (P = 0.199), OPG (P = 0.035), and RANK (P = 0.020) in the experimental group significantly increased from day 7, with a more even distribution than in the control group, and that this difference prevailed until the end of the experiment. Bone density of the experimental group after trichrome staining was also higher than in the control group. These results suggest that LLL irradiation facilitates bone metabolism during bone healing at the sites of deproteinized bovine bone grafts in rats.

Vascular endothelial growth factor expression in cultured periosteal-derived cells.

The purpose of this study was to examine the expression of vascular endothelial growth factor (VEGF) during osteoblastic differentiation of cultured human periosteal-derived cells. Periosteal tissues were obtained from mandible during surgical extraction of lower impacted third molars. Periosteal-derived cells were introduced into cell culture. After passage 3, the periosteal-derived cells were further cultured for 42 days in an osteogenic-inductive culture medium containing dexamethasone, ascorbic acid, and beta-glycerophosphate. The alkaline phosphatase activity in the cultured periosteal-derived cells increased rapidly up to day 14, followed by decrease in activity. The Runx2 protein was expressed at day 7 and day 14, and its expression was not observed thereafter. Both VEGF(165) and VEGF(121) were expressed strongly at days 35 and 42 of culture, particularly during the later stages of differentiation. Alizarin red S-positive nodules were first observed on day 14 and then increased in number during the entire culture period. Osteocalcin and VEGF were first detected in the culture medium on day 14, and their levels increased thereafter in a time-dependent manner. These results suggest that VEGF secretion from cultured human periosteal-derived cells increases along with the mineralization process of the extracellular matrix.

Comparison of treatment outcome and stability between distraction osteogenesis and LeFort I osteotomy in cleft patients with maxillary hypoplasia.

The purpose of this study was to compare treatment outcome and relapse between maxillary advancement surgery with LeFort I osteotomy and maxillary distraction osteogenesis in patients with cleft lip and palate with maxillary hypoplasia. The sample consisted of a maxillary advancement surgery with LeFort I osteotomy group (group 1, N= 14, mean age, 21.7 years) and a maxillary distraction osteogenesis group (group 2, N = 11, mean age, 16.3 years). Lateral cephalograms were taken and traced at presurgery (T0), postsurgery (T1), and postretention (T2). Nine hard and four soft tissue cephalometric variables were measured. Differences in measurements at each stage, treatment outcome (T1-T0), and relapse (T2-T1) were compared between groups with independent t test. Because the amount of surgical movement could affect the amount of relapse, a difference in relapse between two groups was compared by analysis of covariance with the amount of surgical movement as a covariant. Although the amounts of forward movements of A point (P < 0.01), upper incisor (P < 0.001), and upper lip (P < 0.001) during T1-T0 were greater in group 2, there were no significant differences in the amounts of relapse (T2-T1) between the two groups. During T1-T0, counterclockwise rotation of the palatal plane was observed in group 2 as a result of downward movement of posterior nasal spine (PNS) at T1, whereas group 1 had clockwise rotation of palatal plane at T1 because of downward movement of anterior nasal spine (ANS). The amounts of relapse (T2-T1) in vertical movements of PNS and upper incisor were significantly different between the two groups (P < 0.05). The amount of required maxillary advancement, vector control of palatal plane, and vertical position of upper incisor would be important factors when planning a surgical treatment in patients with cleft lip and palate with midface hypoplasia.

Osteogenic phenotypes and mineralization of cultured human periosteal-derived cells.

Stem cells or osteogenic precursor cells isolated from bone marrow, trabecular tissues in bone, cartilage, muscle, and fat are the most suitable source for bone tissue engineering. In this study, we investigated the osteogenic phenotypes and mineralization of cultured human periosteal-derived cells obtained from mandibular periosteums. These periosteal-derived cells were positive for CD44, CD90, and CD166 antigens. They are successfully differentiated into osteoblasts in the medium containing dexamethasone, ascorbic acid, and beta-glycerophosphate. We observed that alkaline phosphatase (ALP) was largely expressed in the earlier stage of osteoblastic differentiation according to histochemical staining and RT-PCR analysis, whereas osteocalcin was dominantly expressed and secreted into the medium at the later stage. In addition, mineralized nodule formation has been observed by von Kossa staining in a time-dependent manner. These results suggest that periosteal-derived cell has the potential osteogenic activity and could be a good candidate for tissue engineering to restore the bony defects of the maxillofacial region.

Effect of low-level laser treatment after installation of dental titanium implant-immunohistochemical study of RANKL, RANK, OPG: an experimental study in rats.

BACKGROUND AND OBJECTIVES: This experiment using an animal experimental model was conducted in order to investigate the effect of low-level laser therapy (LLLT) on the healing of the dental titanium implant. STUDY DESIGN/MATERIALS AND METHODS: The experimental group received LLLT for a week and the control group did not. Each group consisted of 10 rats. Two rats from the groups were euthenized on the days 1, 3, 7, 14, and 21 of the experiment. The expression of receptor activator of nuclear factor kB ligand (RANKL), osteoprotegerin (OPG), and receptor activator of nuclear factor kB (RANK) were investigated. RESULTS: The expression of RANKL was observed from the initial stage of the installation of the implant for both the experimental and control groups. However, the degree of expression was higher in the experimental group. The degree of expression of OPG increased remarkably in the experimental group, while in the control group the degree of expression increased only slightly. In the experimental group, the expression of RANK was observed from the first day, but in the control group, it was weakly observed after day 3. The overall expression within the bone was slight on day 7 in the control group, while an active expression was observed in the experimental group. Bone density after installation of dental titanium implant during osseointegration in the experimental group was higher than the control group. The surface and structure of the titanium implant was not damaged by low-level laser (LLL). CONCLUSIONS: From the above results, the expression of OPG, RANKL, and RANK during the osseointegration of the dental titanium implant was observed within bone tissue. The application of the LLL influenced the expression of OPG, RANKL, and RANK, and resulted in the expansion of metabolic bone activity and increased the activity of bone tissue cells.

A retrospective analysis of 20 surgically corrected bimaxillary protrusion patients.

This paper presents a retrospective review and analysis of 20 bimaxillary protrusion patients who visited the authors' hospital between 1986 and 1998 following surgical correction. The lateral cephalometric radiographs of each patient were taken preoperatively (T0), within 1 week after surgery (T1), and at least 1 postoperative year later (T2). Hard and soft tissue analysis was performed on each cephalometric radiograph. The matched pair t test was employed for T0-T1, T1-T2, and T0-T2 periods. The sample consisted of 20 Korean adult patients with bimaxillary protrusion (18 women and 2 men), aged 21 to 33 years. The first premolars were removed in 18 of the 20 cases. The Wunderer method was selected in 18 of the 20 maxillary cases, and the anterior subapical osteotomy was selected in all mandibular cases. Augmentation genioplasty was combined in 3 cases, and reduction glossoplasty was combined in 2 cases. Orthodontic treatment was accompanied in 8 cases. The statistical analysis of all the variables revealed that, except for overbites, there were significant differences between T1-T2 and between T0-T2 periods (P < .01). This suggests that most of the bimaxillary patients want instant esthetic facial results and that their soft tissue profiles were improved significantly. However, the postoperative course should be cautiously observed.