Long-term Stability Over 2 Years After Isolated Maxillary Orthognathic Surgery Combined With Mandibular Autorotation in Risk Patients for Condylar Resorption.

OBJECTIVE: Counterclockwise rotation of mandible can cause condylar resorption and condylar displacement posteroinferiorly after maxillary orthognathic surgery with mandibular in patients with high-angle mandibular retrognathism. This study was aimed to evaluate long-term stability >2 years and postoperative changes of condylar displacement. MATERIALS AND METHODS: In 15 patients who underwent Le Fort I osteotomy with mandibular autorotation, postoperative stability was cephalometrically investigated until 2 years. Condylar changes were analyzed with transcranial temporomandibular joint projection. Correlation between condylar displacement and surgical movement was analyzed. RESULTS: Significant clockwise relapse of mandible ( P <0.01 for SNB reduction and backward movement of point B) was observed between 6 months and >2 years after surgery, even though the values were small (0.5±0.1 degrees and 1.14±0.13 mm, respectively). The condyle was displaced posteroinferiorly immediately after surgery; however, it achieved a stable position at postoperative 6 weeks. The amount of vertical condylar displacement was significantly correlated with surgical change in mandibular posterior border sagittal angle, palatal plane angle, facial height ratio, and point B in the horizontal dimension. Greater mandibular rotation prompted more vertical condylar displacement. CONCLUSIONS: Small mandibular relapse in long term should be considered after maxillary orthognathic surgery with mandibular autorotation, although it is regarded as a surgical maneuver to minimize mandibular instability in patients susceptible to postoperative condylar resorption.

Effects of 17ß-Estradiol Deficiency and Mechanical Overload on Osseous Changes in the Rat Temporomandibular Joint.

PURPOSE: To deduce the contributing factors to idiopathic condylar resorption in young female patients, we hypothesized that 17ß-estradiol (E2) deficiency would cause arthritic changes in the mandibular condyle under mechanical overloading in a rat model. We also hypothesized that osseous changes in the microstructure by the combination of E2 deficiency and mechanical overloading would be different depending on the region of the condyle. MATERIALS AND METHODS: The mandibular condyles of female Sprague-Dawley rats were mechanically overloaded (50g) 8 weeks after an ovariectomy (OVX). Changes in the condyles were analyzed with micro-computed tomography and histochemical and immunohistochemical staining. RESULTS: The size of the mandibular condyle decreased significantly with OVX or mechanical loading. The incidence of arthritic changes, including osteophyte formation, bone erosion, and flattening, was significantly different between the sham and OVX groups. The posterior parts of the condyles showed poor bone quality before OVX, and their condition significantly worsened with reduced bone mineral density and bone volume/tissue volume, as well as a sparse trabecular pattern. CONCLUSIONS: E2 deficiency and mechanical overloading of the temporomandibular joint cause morphologic changes in the mandibular condyle and changes in the osseous microstructure, which are more apparent in areas of poor bone quality.

Quantitative Augmented Reality-Assisted Free-Hand Orthognathic Surgery Using Electromagnetic Tracking and Skin-Attached Dynamic Reference.

The purpose of this study was to develop a quantitative AR-assisted free-hand orthognathic surgery method using electromagnetic (EM) tracking and skin-attached dynamic reference. The authors proposed a novel, simplified, and convenient workflow for augmented reality (AR)-assisted orthognathic surgery based on optical marker-less tracking, a comfortable display, and a non-invasive, skin-attached dynamic reference frame. The 2 registrations between the physical (EM tracking) and CT image spaces and between the physical and AR camera spaces, essential processes in AR-assisted surgery, were pre-operatively performed using the registration body complex and 3D depth camera. The intraoperative model of the maxillary bone segment (MBS) was superimposed on the real patient image with the simulated goal model on a flat-panel display, and the MBS was freely handled for repositioning with respect to the skin-attached dynamic reference tool (SRT) with quantitative visualization of landmarks of interest using only EM tracking. To evaluate the accuracy of AR-assisted Le Fort I surgery, the MBS of the phantom was simulated and repositioned by 6 translational and three rotational movements. The mean absolute deviations (MADs) between the simulation and post-operative positions of MBS landmarks by the SRT were 0.20, 0.34, 0.29, and 0.55 mm in x- (left lateral, right lateral), y- (setback, advance), and z- (impaction, elongation) directions, and RMS, respectively, while those by the BRT were 0.23, 0.37, 0.30, and 0.60 mm. There were no significant differences between the translation and rotation surgeries or among surgeries in the x-, y-, and z-axes for the SRT. The MADs in the x-, y-, and z-axes exhibited no significant differences between the SRT and BRT. The developed method showed high accuracy and reliability in free-hand orthognathic surgery using EM tracking and skin-attached dynamic reference.

Extensive Surgical Procedures Result in Better Treatment Outcomes for Bisphosphonate-Related Osteonecrosis of the Jaw in Patients With Osteoporosis.

PURPOSE: To identify the risk factors associated with relapse or treatment failure after surgery for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in patients with osteoporosis. PATIENTS AND METHODS: We performed a retrospective cohort study of BRONJ in patients with osteoporosis who had undergone surgical procedures from 2004 to 2016 at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The predictor variables were a set of heterogeneous variables, including demographic (age, gender), anatomic (maxilla or mandible, or both, affected location), clinical (disease stage, etiology, comorbidities, history of intravenous bisphosphonate intake), time (conservative treatment before surgery, bisphosphonate treatment before the development of BRONJ, discontinuation of the drug before surgery, interval to final follow-up, interval to reoperation in the case of relapse or treatment failure), and perioperative variables (type of anesthesia, type of surgical procedures). The primary outcome variable was relapse after surgery that required reoperation (yes vs no). The descriptive and bivariate statistics were computed to assess the relationships between the study variables and the outcome. To determine the risk factors, we conducted a survival analysis using the Cox model. RESULTS: The final sample included 325 subjects with a median age of 75 years, and 97% were women. After surgery, 30% of patients did not completely recuperate and underwent repeat surgery. The interval from the first surgery to reoperation ranged from 10 days to 5.6 years. Relapse or treatment failure most often occurred immediately after surgery. The type of surgical procedure and mode of anesthesia were the most important factors in the treatment outcome. A drug holiday did not appear to influence the likelihood of relapse after surgery. CONCLUSIONS: Treatment of BRONJ in patients with osteoporosis might benefit from more careful and extensive surgical procedures rather than curettage performed with the patient under local anesthesia.

Maxillary Expansion and Mandibular Setback Surgery With and Without Mandibular Anterior Segment Osteotomy to Correct Mandibular Prognathism With Obstructive Sleep Apnea.

Mandibular prognathism is usually treated with mandibular setback surgery. However, this approach reduces the pharyngeal airway space, and can aggravate obstructive phenomena in patients with obstructive sleep apnea (OSA). While maxillary expansion is known to lead to an increase in the pharyngeal airway volume (PAS), its effect on the PAS in mandibular setback surgery has not yet been reported. The authors report a surgical approach with maxillary expansion in 2 patients with mandibular prognathism that was accompanied by OSA: maxillary midsagittal expansion with minimum maxillary advancement and minor mandibular setback without mandibular anterior segmental osteotomy (ASO) or major mandibular setback with mandibular ASO. Preoperative and postoperative computed tomography and polysomnography indicated that OSA was improved and pharyngeal airway space was increased or sustained, and the prognathic profile could be corrected to an acceptable facial esthetic profile. In summary, maxillary transversal expansion and mandibular setback with or without mandibular ASO can be successfully applied to treat mandibular prognathism with OSA.

Repositioning of the Maxillomandibular Complex Using Maxillary Template Adjusted Only by Maxillary Surface Configuration Without an Intermediate Splint in Orthognathic Surgery.

Accurate repositioning of the maxillary and mandibular segment is essential to improve esthetics and function in orthognathic surgery. With the improvement of three-dimensional imaging technology and computer-aided design and manufacturing techniques, various computer-aided design and manufacturing templates have been developed as alternatives to the traditional error-prone and time-consuming intermediate splint. However, the majority of previously developed templates still use an intermediate splint or the structures connected to occlusal surface and transferred the preoperative virtual plan to the real operation field indirectly.Here, the authors introduce a technical note regarding maxillary surgical templates adjusted only by the maxillary surface configuration. These templates consist of osteotomy and repositioning guide templates that provide information about the osteotomy line, bony interference, and planned position and eliminate the need for an intermediate splint. Using these templates, the maxillomandibular complex can be successfully repositioned without using an intermediate splint. Further studies are needed to determine the accuracy and stability of maxillary templates.

Bone healing of an unfixed bone fragment of the distal segment in sagittal split ramus osteotomy.

In bilateral sagittal split ramus osteotomy for the correction of asymmetry of the mandible, yawing movement of the distal segment can displace the proximal segment. This displacement can be minimized through osteotomy of the posterior part of the distal segment (ie, distal cutting). This free bone fragment is usually removed because of the difficulty of fixation. No previous studies have examined whether union of the bone fragment after distal cutting could join and consequently strengthen the thinned mandibular posterior border. This study used CT imaging to evaluate bone union of the unfixed bone fragment at 3 months postoperatively. The location of the bone fragment and the morphology of bone healing were evaluated in 2D and 3D. The amount of cancellous bone healing between the free bone segment and the proximal segment averaged 63.69%. There was no correlation between the size of the bone gap and the degree of bone union. In most cases, the free bone fragment was located between the distal and proximal segments and tended to dislocate in an anterior-superior direction. Because the postoperative follow-up period was only 3 months, a longer-term study of the changes in bone volume after remodeling is necessary.

Comparison of whole blood collection and double-unit erythrocytapheresis in preoperative autologous blood donation.

INTRODUCTION: We compared preoperative autologous blood donation (PABD) using serial manual whole blood (WB) and PABD using a single session, double-unit erythrocytapheresis in terms of the hemodynamic recovery and clinical outcomes. MATERIALS AND METHODS: This study included 56 donors in the WB PABD group and 117 donors in the double-unit erythrocytapheresis PABD group. All subjects were men with body weight >70 kg, Hb level >13.3g/dL, Hct >40%, and who were scheduled for oral and maxillofacial surgery. Three cycles of manual WB collection for PABD or a single session, double-unit erythrocytapheresis using the Alyx was performed. RESULTS: There were no significant differences in donor demographic variables including age, height, weight, Hb, Hct, or red cell mass between the 2 groups. The double-unit erythrocytapheresis was completed earlier than the last manual WB PABD (at 15.3 ± 4.7 days and 6.5 ± 3.2 days before surgery, p<0.001). Hct values before surgery were higher in the double-unit erythrocytapheresis PABD group than in the manual WB PABD group (39.7 ± 3.2 vs. 38.6 ± 2.7, p=0.024). ΔHct and %ΔHct before the first PABD and before surgery were lower in the double-unit erythrocytapheresis PABD group than in the manual WB PABD group (-5.6 ± 2.8 vs. -6.8 ± 2.7, p=0.010 and -12.3 ± 5.9 vs. -14.8 ± 5.6, p=0.008, respectively). The incidence of additional allogeneic blood transfusions during or after surgery and the post-operative Hb and Hct values were similar in the 2 groups. The length of hospital stay after surgery was significantly longer in the manual WB PABD group than in the double-unit erythrocytapheresis group (6.1 ± 2.5 vs. 5.4 ± 1.9, p=0.043). Of the 33 donors in the double-unit erythrocytapheresis PABD group, 7 (21.2%) reported discomforts related to the procedure, and 6 graded the discomforts (hypocalcemia, perioral tingling sense, paresthesia, dizziness, stuffiness, pain on the intravenous site, and muscle tension) as mild. CONCLUSION: The single session, double-unit erythrocytapheresis prolonged the time interval between PABD and surgery and led to better hemodynamic recovery than the serial manual WB PABD, and hypocalcemic symptoms were mild.

Posterior ostectomy of a mandibular distal segment for nerve bundle traction to tensionless anastomosis of an inferior alveolar nerve.

Tensionless adaptation of nerve ends is a challenging task in the repair of damaged inferior alveolar nerve (IAN). A new technique is introduced with posterior ostectomy of a mandibular distal segment after sagittal splitting for nerve bundle traction to tensionless anastomosis of nerve ends. We were able to create tensionless anastomosis of an IAN defect without autogenous or alloplastic graft using this method. This method is suitable for neurorrhaphy after neuroma removal in cases of IAN damage during dental procedures.

Treatment of anterior open bite and an ankylosed incisor by applying multiloop edgewise archwire, mini-implants, and dentoalveolar distraction.

An 18.7-year-old female patient with an anterior open bite and an ankylosed left maxillary central incisor was referred from a private orthodontic clinic. Canine relationships were Class II and molar relationships were Class I. The open bite was closed with the multiloop edgewise archwire and up-and-down elastics. The maxillary left central incisor was extruded by dentoalveolar distraction assisted with mini-implants. Active treatment took 2 years and 1 month, and the treatment result remained stable 14 months after debonding.

An Education-Counseling Program for Young Prehypertensive Adults.

In this non-equivalent control group, non-synchronized study, we assessed the effects of an education-counseling program for young prehypertensive adults. We included 40 and 47 prehypertensive individuals in the experimental and control groups, respectively. A structured questionnaire (pretest) was used to assess prehypertension-related knowledge, attitudes, health-promoting behavior, and self-efficacy. The experimental group underwent the 8-week program, while the control group received basic prehypertension and self-management education. Subsequently, blood pressure (BP) was measured, and prehypertension-related knowledge, attitudes, health-promoting behavior, and self-efficacy were evaluated using a questionnaire (posttest). There were significant intergroup differences in knowledge (t = 3.04, p = .003), attitudes (t = 6.41, p < .001), behavior (t = 11.60, p < .001), self-efficacy (t = 11.76, p < .001), and systolic BP (t = -5.49, p < .001); however, diastolic BP was not significantly different (t = -0.73, p = .473). Our findings demonstrated that the program is effective in improving knowledge, attitudes, behavior, self-efficacy, and systolic BP. Therefore, it can be used to prevent progression to hypertension.

Enhanced Bone Regeneration by Bone Morphogenetic Protein-2 after Pretreatment with Low-Intensity Pulsed Ultrasound in Distraction Osteogenesis.

BACKGROUND: Bone morphogenetic protein 2 (BMP-2) and low-intensity pulsed ultrasound (LIPUS) have been used to enhance bone healing in distraction osteogenesis (DO). The aim of this study was to assess the synergistic effect of BMP-2 and LIPUS on bone regeneration in DO and to determine the optimal treatment strategy for enhanced bone regeneration. METHODS: Rat mesenchymal stromal cells were treated with various application protocols of BMP-2 and LIPUS, and cell proliferation, alkaline phosphatase activity, and osteogenesis-related marker expression were evaluated. In vivo experiments were performed in a rabbit DO model according to the application protocols with different timings of BMP-2 and LIPUS application. RESULTS: Application of BMP-2 after LIPUS pretreatment (BMP-2 after LIPUS) showed greater cell proliferation than LIPUS treatment alone, and higher ALP activity than all other treatment protocols. BMP-2 after LIPUS also exhibited increased gene expression levels of ALP, Cbfa1, and Osterix compared with LIPUS treatment alone. In vivo experiments revealed no significant differences in bone healing based on the timing of LIPUS treatment in DO. The combination of BMP-2 and LIPUS resulted in increased bone volume and bone mineral density compared with BMP-2 or LIPUS. Regarding the timing of BMP-2 application, the application of BMP-2 after LIPUS pretreatment led to greater bone volume than the application of BMP-2 before LIPUS. CONCLUSION: The results of this study suggest that the combined treatment of BMP-2 and LIPUS can lead to enhanced bone healing in DO and that effective bone healing can be achieved through the application of LIPUS before BMP-2.

Clinical and radiographic outcomes of dental implant after maxillary sinus floor augmentation with rhBMP-2/hydroxyapatite compared to deproteinized bovine bone.

OBJECTIVES: This study aimed to evaluate the clinical and radiographic outcomes of early implant placement and functional loading in maxillary sinus floor augmentation (MSFA) using recombinant human bone morphogenetic protein 2/hydroxyapatite (rhBMP-2/HA) and to compare these outcomes with those of the conventional protocol in MSFA using deproteinized bovine bone (DBB). MATERIALS AND METHODS: The rhBMP-2/HA and DBB groups consisted of 14 and 13 patients who underwent MSFA with BMP and DBB, respectively. After placement of 22 implants and 21 implants in the rhBMP-2/HA and DBB groups, respectively, abutment connections were performed 3 months after implant placement for the rhBMP-2/HA group and 6 months after implant placement for the DBB group. Changes in grafted sinus height (GSH), marginal bone loss (MBL), and implant stability were evaluated up to one year after functional loading. RESULTS: Survival rates for the rhBMP-2/HA and DBB groups after one year of functional loading were 90.9% and 90.5%, respectively. Both groups exhibited no significant time-course changes in GSH until one year of functional loading (rhBMP-2/HA, p = 0.124; DBB, p = 0.075). Although significant MBL occurred after one year of functional loading for both groups (rhBMP-2/HA, p < 0.001; DBB, p < 0.001), there were no significant differences in time-course changes in MBL between the two groups (p = 0.450). The mean implant stability quotient values in the rhBMP-2/HA and DBB groups were 75.3 and 75.4 after one year of functional loading, respectively, and there were no significant differences between the two groups (p = 0.557). CONCLUSIONS: MSFA using rhBMP-2/HA allowed implant rehabilitation with early implant placement and functional loading and led to a comparable survival rate and implant stability after 1 year of functional loading with acceptable MBL and stable maintenance of GSH compared to the MSFA using DBB with 6 months of healing after implant placement.

Preliminary approach of real-time monitoring in vitro matrix mineralization based on surface plasmon resonance detection.

Matrix mineralization is a terminal process in osteoblast differentiation, and several approaches have been introduced to characterize the process in tissues or cultured cells. However, an analytical technique that quantitates in vitro matrix mineralization of live cells without any labeling or complex treatments is still lacking. In this study, we investigate a simple and enhanced optical method based on surface plasmon resonance (SPR) detection that can monitor the surface-limited refractive index change in real-time. During monitoring MC3T3-E1 cells in vitro culture every 2 days for over 4 weeks, the SPR angle is shifted with a greater resonance change in cells cultured with osteogenic reagents than those without the reagents. In addition, the SPR results obtained have a close relevance with the tendency of conventional mineralization staining and an inductively coupled plasma-based calcium content measure. These results suggest a new approach of a real-time SPR monitoring in vitro matrix mineralization of cultured cells.

Robot-Assisted Maxillary Positioning in Orthognathic Surgery: A Feasibility and Accuracy Evaluation.

Several methods enabling independent repositioning of the maxilla have been introduced to reduce intraoperative errors inherent in the intermediate splint. However, the accuracy is still to be improved and a different approach without time-consuming laboratory process is needed, which can allow perioperative modification of unoptimized maxillary position. The purpose of this study is to assess the feasibility and accuracy of a robot arm combined with intraoperative image-guided navigation in orthognathic surgery. The experiments were performed on 12 full skull phantom models. After Le Fort I osteotomy, the maxillary segment was repositioned to a different target position using a robot arm and image-guided navigation and stabilized. Using the navigation and the postoperative computed tomography (CT) images, the achieved maxillary position was compared with the planned position. Although the maxilla showed mild displacement during the fixation, the mean absolute deviations from the target position were 0.16 mm, 0.18 mm, and 0.20 mm in medio-lateral, antero-posterior, and supero-inferior directions, respectively, in the intraoperative navigation. Compared with the target position using postoperative CT, the achieved maxillary position had a mean absolute deviation of less than 0.5 mm for all dimensions and the mean root mean square deviation was 0.79 mm. The results of this study suggest that the robot arm combined with the intraoperative image-guided navigation may have great potential for surgical plan transfer with the accurate repositioning of the maxilla in the orthognathic surgery.

Comparison of condylar displacement after sagittal split ramus osteotomy depending on the glenoid fossa depth.

This study aimed to evaluate the relationship between postoperative condylar displacement (PCD) after sagittal split ramus osteotomy (SSRO) and the glenoid fossa depth. A total of 29 patients who underwent computed tomography (CT) before surgery (T0), immediately after (T1), and 6 months after (T2) surgery were studied. The fossa depth was measured, and the amount of displaced condylar center and axis were evaluated on CT at T0, T1, and T2 using three-dimensional analysis software. PCD and the fossa depth relationship was investigated by Pearson's correlation analysis. The fossa depth varied from 3.9 mm to 12.0 mm, and the mean value was 8.15 ± 1.60 mm. The condylar center was displaced by 1.12 ± 0.66 mm at T1 compared with it at T0. The amount of displaced condylar center negatively correlated with the fossa depth (r = -0.424, p = 0.001). The displacement of the condylar center between T0 and T2 was 0.85 ± 0.51 mm. The amount of condylar center displacement between T0 and T1 showed a positive correlation with it between T0 and T2 (r = 0.481, p < 0.001). In conclusion, more attention is needed in patients with small fossa depth during condylar repositioning after SSRO and postoperative management to minimize complications.

Efficacy and safety of rhBMP/ß-TCP in alveolar ridge preservation: a multicenter, randomized, open-label, comparative, investigator-blinded clinical trial.

BACKGROUND: The aim of this multicenter, randomized, open-label, comparative, investigator-blinded study was to investigate the efficacy and safety of recombinant human bone morphogenetic protein 2 (rhBMP-2) combined with ß-TCP (rhBMP-2/ß-TCP) in alveolar ridge preservation. MATERIALS AND METHODS: Eighty-four subjects from three centers were enrolled in this clinical trial. After tooth extraction, rhBMP-2/ß-TCP (n = 41, test group) or ß-TCP (n = 43, control group) were grafted to the extraction socket with an absorbable barrier membrane for alveolar ridge preservation. Using computed tomography images obtained immediately after and 12 weeks after surgery, changes in the alveolar bone height and width were analyzed for each group and compared between the two groups. RESULTS: Both the test and control groups showed a significant decrease in alveolar bone height in the 12 weeks after surgery (both groups, p < 0.0001). However, the test group exhibited a significantly lower decrease in alveolar bone height than the control group (p = 0.0004). Alveolar bone width also showed significantly less resorption in the test group than in the control group for all extraction socket levels (ESL) (p = 0.0152 for 75% ESL; p < 0.0001 for 50% ESL; p < 0.0001 for 25% ESL). There were no statistically significant differences in the incidence of adverse events between the two groups. No severe adverse events occurred in either group. CONCLUSIONS: The results of this study suggest that rhBMP-2/ß-TCP is a safe graft material that provides a high alveolar bone preservation effect in patients receiving dental extraction. TRIAL REGISTRATION: Clinicaltrials.gov , NCT02714829 , Registered 22 March 2016.

A Complete Digital Workflow for Planning, Simulation, and Evaluation in Orthognathic Surgery.

The purpose of this study was to develop a complete digital workflow for planning, simulation, and evaluation for orthognathic surgery based on 3D digital natural head position reproduction, a cloud-based collaboration platform, and 3D landmark-based evaluation. We included 24 patients who underwent bimaxillary orthognathic surgery. Surgeons and engineers could share the massive image data immediately and conveniently and collaborate closely in surgical planning and simulation using a cloud-based platform. The digital surgical splint could be optimized for a specific patient before or after the physical fabrication of 3D printing splints through close collaboration. The surgical accuracy was evaluated comprehensively via the translational (linear) and rotational (angular) discrepancies between identical 3D landmarks on the simulation and postoperative computed tomography (CT) models. The means of the absolute linear discrepancy at eight tooth landmarks were 0.61 ± 0.55, 0.86 ± 0.68, and 1.00 ± 0.79 mm in left-right, advance-setback, and impaction-elongation directions, respectively, and 1.67 mm in the root mean square direction. The linear discrepancy in the left-right direction was significantly different from the other two directions as shown by analysis of variance (ANOVA, p < 0.05). The means of the absolute angular discrepancies were 1.43 ± 1.06°, 0.50 ± 0.31°, and 0.58 ± 0.41° in the pitch, roll, and yaw orientations, respectively. The angular discrepancy in the pitch orientation was significantly different from the other two orientations (ANOVA, p < 0.05). The complete digital workflow that we developed for orthognathic patients provides efficient and streamlined procedures for orthognathic surgery and shows high surgical accuracy with efficient image data sharing and close collaboration.

Comparison of a synthetic bone substitute composed of carbonated apatite with an anorganic bovine xenograft in particulate forms in a canine maxillary augmentation model.

OBJECTIVE: To evaluate the effect of a porous geometry in particulate bone on new bone formation by comparison of anorganic bovine carbonate apatite (ABCA) with synthetic carbonated apatite (SCA), which have similar properties but different micro-structures. MATERIAL AND METHODS: Porous structures and anorganic components of ABCA and SCA were evaluated using scanning electron microscope and Fourier transform infrared. They were implanted in maxillary augmentation models with the mouth split design in a total of 15 Beagle dogs. The animals were sacrificed 4, 8 and 16 weeks after surgery, and the histomorphometrical results were statistically analyzed for the material's geometrical relationship and new bone formation in relation to the available space and contact surface for osteoconduction. RESULTS: Both materials showed a typical infrared pattern of CO(3)(2-) -substituted hydroxyapatite (HA). Porous structures and a bridging effect of osteoconductive bone material were relatively better observed in SCA. The ratio of the material area to the total area was higher (P<0.01) for ABCA (28.03±6.09) than for SCA (20.26±4.23). The ratio of the number of particles possessing a pore structure to the total number and the interparticular space was greater (P<0.001 and 0.01) for SCA (18.12±9.44 and 79.74±4.23) compared with ABCA (1.45±1.74 and 71.63±5.85). The new bone areas and the bone-material contact lengths were greater in SCA than in ABCA (P<0.05). CONCLUSIONS: The present study showed that porous structures may have an influence on new bone formation in osteoconductive bone substitutes.

High power-pulsed Nd:YAG laser as a new stimulus to induce BMP-2 expression in MC3T3-E1 osteoblasts.

BACKGROUND AND OBJECTIVE: High-power laser has recently become a physical stimulus for bone regeneration. Little is known about how high-power laser irradiation affects osteoblast differentiation. This study investigated osteoblast responses to high-power laser and combined irradiation with BMP-2 treatment. STUDY DESIGN/MATERIALS AND METHODS: MC3T3-E1 pre-osteoblasts were exposed to laser irradiation, 100 ng/ml BMP-2 or both. Cells were irradiated with a Q-switched, pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, with a 1,064 nm wavelength and 0.75 W output power under 1.5, 3, or 5 J/cm(2) energy densities. Cell proliferation was evaluated using tetrazolium salt, WST-8. To determine the effect of these treatments on in vitro osteogenesis, we examined alkaline phosphatase (ALP) activity, mineral deposition, and expression of genes associated with osteogenesis. Quantitative real time PCR or ELISA was used to examine cytokine expression. In each experiment, either non-irradiated or BMP-2 (100 ng/ml)-treated cells were used as controls. RESULTS: High-power, low-level, Nd:YAG laser irradiation significantly increased ALP activity, when combined with BMP-2 or not. Cell proliferation declined in the irradiation and combined irradiation/BMP-2 groups. Interestingly, Nd:YAG laser stimulation resulted in significant induction of endogenous BMP-2 protein and gene expression. The increased expression of upstream regulators cbfa1 by Nd:YAG laser alone was comparable to exogenous BMP-2 treatment (100 ng/ml). Combined laser/BMP-2 treatment was synergistic in the expression of some genes (IGF-1, cbfa1) and ALP activity, compared to both BMP-2 treatment and laser irradiation alone. In vitro matrix mineralization was significantly accelerated by laser stimulation compared to that of the control, more so than with the combined laser/BMP-2 treatment. CONCLUSIONS: The present in vitro findings demonstrate that high-power, low-level Nd:YAG laser increased osteoblast activity, very efficiently accelerating mineral deposition. Osteoinductive effect of laser is likely mediated by activation of BMP-2-related signaling pathway.