Longitudinal effects of estrogen on mandibular growth and changes in cartilage during the growth period in rats.

Estrogen is a steroid hormone that induces skeletal growth and affects endochondral ossification of the long tubular bone growth plate during the growth period. However, the effects of estrogen on endochondral ossification of the mandibular condylar cartilage are unclear. In this study, ovariectomized Wistar/ST rats were used to investigate the longitudinal effects of estrogen on mandibular growth. The rats were administered different doses of estrogen. Longitudinal micro-computed tomographic scanning, histological staining and ELISA on plasma growth hormone were performed to examine the effects of estrogen on mandibular growth. The results showed that mandibular growth was suppressed throughout the growth period by estrogen in a dose-dependent manner. In addition, long-term administration of a high dose of estrogen to the rats resulted in significant increase in growth hormone throughout the growth period, significant circularization of cell nuclei in the proliferative layer, intensely staining cartilage matrix in the subchondral bone, and significant suppression of estrogen receptor (ER) alpha and beta expression in the mandibular cartilage. However, regardless of estrogen concentration, in the posterior part of the mandibular cartilage, ER expression extended to both the hypertrophic and proliferative layers. These results indicate that estrogen suppresses mandibular growth throughout the growth period. Additionally, it influences endochondral ossification via its effect on ERs.

Effect of CD146+ SHED on bone regeneration in a mouse calvaria defect model.

OBJECTIVE: Stem cells from human exfoliated deciduous teeth (SHED) have bone regeneration ability and potential therapeutic applications. CD146, a cell adhesion protein expressed by vascular endothelial cells, is involved in osteoblastic differentiation of stem cells. The effect of CD146 on SHED-mediated bone regeneration in vivo remains unknown. We aimed to establish efficient conditions for SHED transplantation. MATERIALS AND METHODS: SHED were isolated from the pulp of an extracted deciduous tooth and cultured; CD146-positive (CD146+ ) and CD146-negative (CD146- ) populations were sorted. Heterogeneous populations of SHED and CD146+ and CD146- cells were transplanted into bone defects generated in the skulls of immunodeficient mice. Micro-computed tomography was performed immediately and 4 and 8 weeks later. Histological and immunohistochemical assessments were performed 8 weeks later. RESULTS: Bone regeneration was observed upon transplantation with CD146+ and heterogeneous populations of SHED, with significantly higher bone regeneration observed with CD146+ cells. Bone regeneration was higher in the CD146- group than in the control group, but significantly lower than that in the other transplant groups at 4 and 8 weeks. Histological and immunohistochemical assessments revealed that CD146+ cells promoted bone regeneration and angiogenesis. CONCLUSION: Transplantation of CD146+ SHED into bone defects may be useful for bone regeneration.

High-frequency near-infrared semiconductor laser irradiation suppressed experimental tooth movement-induced inflammatory pain markers in the periodontal ligament tissues of rats.

High-frequency near-infrared (NIR) semiconductor laser-irradiation has an unclear effect on nociception in the compressed lateral periodontal ligament region, a peripheral nerve region. This study aimed to investigate the effects of NIR semiconductor laser irradiation, with a power of 120 J, on inflammatory pain markers and neuropeptides induced in the compressed lateral periodontal ligament area during ETM. A NIR semiconductor laser [910 nm wavelength, 45 W maximum output power, 300 mW average output power, 30 kHz frequency, and 200 ns pulse width (Lumix 2; Fisioline, Verduno, Italy)] was used. A nickel-titanium closed coil that generated a 50-g force was applied to the maxillary left-side first molars and incisors in 7-week-old Sprague-Dawley (280-300 g) rats to induce experimental tooth movement (ETM) for 24 h. Ten rats were divided into two groups (ETM + laser, n = 5; ETM, n = 5). The right side of the ETM group (i.e., the side without induced ETM) was evaluated as the untreated group. We performed immunofluorescent histochemistry analysis to quantify the interleukin (IL)-1ß, cyclooxygenase-2 (COX2), prostaglandin E2 (PGE2), and neuropeptide [calcitonin gene-related peptide (CGRP)] expression in the compressed region of the periodontal tissue. Post-hoc Tukey-Kramer tests were used to compare the groups. Compared with the ETM group, the ETM + laser group showed significant suppression in IL-1ß (176.2 ± 12.3 vs. 310.8 ± 29.5; P < 0.01), PGE2 (104.4 ± 14.34 vs. 329.6 ± 36.52; P < 0.01), and CGRP (36.8 ± 4.88 vs. 78.0 ± 7.13; P < 0.01) expression. High-frequency NIR semiconductor laser irradiation exerts significant effects on ETM-induced inflammation. High-frequency NIR semiconductor laser irradiation can reduce periodontal inflammation during orthodontic tooth movement.

The Physiological Function of Deglutition and Swallowing in Patients With Maxillary Protrusion After Mandibular Advancement.

The objective of this study was to determine the tongue-palatal contact changes in patients with skeletal maxillary protrusion after sagittal split ramus osteotomy (SSRO) during swallowing. In this study, 15 patients with maxillary protrusion and 10 normal subjects participated. Before and 3 months after surgery, tongue-palatal contact patterns during swallowing of patients with maxillary protrusion as well as controls were evaluated by electropalatography. The electrode contact number in the alveolar, palatal, and velar parts was examined. The swallowing duration of each phase was also evaluated. In the lateral area of the velar part, incomplete electrode contact was shown at 0.3 seconds in patients with maxillary protrusion. The electrode contact number in the velar part at 0.3 seconds before tongue-palatal complete contact was significantly less in the preoperative patients compared with the controls ( P < 0.05). A small increase in the electrode contact number of the velar part was shown in the postoperative patients at 0.3 and 0.2 seconds before tongue-palatal complete contact ( P < 0.05). The pharyngeal phase duration was significantly larger in the patients with maxillary protrusion before SSRO compared with the controls ( P < 0.05). After SSRO, the pharyngeal phase duration was significantly shortened. It was shown that the tongue-palatal contact pattern during swallowing in patients with maxillary protrusion improved after orthognathic surgery, and the pharyngeal phase duration was also shortened. It is suggested that the changes in the mesiodistal mandibular position by orthognathic surgery can improve tongue posture and movement during swallowing.

Bone Differentiation Ability of CD146-Positive Stem Cells from Human Exfoliated Deciduous Teeth.

Regenerative therapy for tissues by mesenchymal stem cell (MSCs) transplantation has received much attention. The cluster of differentiation (CD)146 marker, a surface-antigen of stem cells, is crucial for angiogenic and osseous differentiation abilities. Bone regeneration is accelerated by the transplantation of CD146-positive deciduous dental pulp-derived mesenchymal stem cells contained in stem cells from human exfoliated deciduous teeth (SHED) into a living donor. However, the role of CD146 in SHED remains unclear. This study aimed to compare the effects of CD146 on cell proliferative and substrate metabolic abilities in a population of SHED. SHED was isolated from deciduous teeth, and flow cytometry was used to analyze the expression of MSCs markers. Cell sorting was performed to recover the CD146-positive cell population (CD146+) and CD146-negative cell population (CD146-). CD146 + SHED without cell sorting and CD146-SHED were examined and compared among three groups. To investigate the effect of CD146 on cell proliferation ability, an analysis of cell proliferation ability was performed using BrdU assay and MTS assay. The bone differentiation ability was evaluated using an alkaline phosphatase (ALP) stain after inducing bone differentiation, and the quality of ALP protein expressed was examined. We also performed Alizarin red staining and evaluated the calcified deposits. The gene expression of ALP, bone morphogenetic protein-2 (BMP-2), and osteocalcin (OCN) was analyzed using a real-time polymerase chain reaction. There was no significant difference in cell proliferation among the three groups. The expression of ALP stain, Alizarin red stain, ALP, BMP-2, and OCN was the highest in the CD146+ group. CD146 + SHED had higher osteogenic differentiation potential compared with SHED and CD146-SHED. CD146 contained in SHED may be a valuable population of cells for bone regeneration therapy.

Head and neck cancer patients show poor oral health as compared to those with other types of cancer.

PURPOSE: Several studies have found associations between periodontitis and various types of cancer. Since the site of head and neck cancer (HNC) has contiguity or proximity to the oral cavity, it may be particularly influenced by oral inflammation. This study aimed to determine whether HNC patients have poor oral health as compared to those with other types of cancer. METHODS: This study retrospectively examined oral environmental factors including periodontal inflamed surface area (PISA), a new periodontal inflammatory parameter. A total of 1030 cancer patients were divided into the HNC (n = 142) and other cancer (n = 888) groups. Furthermore, the HNC group was divided into high (n = 71) and low (n = 71) PISA subgroups, and independent risk factors affecting a high PISA value were investigated. RESULTS: Multivariate logistic regression analysis showed that number of missing teeth (odds ratio 1.72, 95% CI 1.15-2.56, P < 0.01), PISA (odds ratio 1.06, 95% CI 1.03-1.06, P < 0.05), and oral bacterial count (odds ratio 1.02, 95% CI 1.01-1.03, P < 0.01) were independent factors related to HNC. In addition, multivariate logistic regression analysis indicated that current smoker (odds ratio 7.51, 95% CI 1.63-34.71, P < 0.01) and presence of untreated dental caries (odds ratio 3.33, 95% CI 1.23-9.00, P < 0.05) were independent risk factors affecting high PISA values in HNC patients. CONCLUSION: HNC patients have higher levels of gingival inflammation and poor oral health as compared to patients with other types of cancer, indicating that prompt oral assessment and an effective oral hygiene management plan are needed at the time of HNC diagnosis.

Correction of Severe Skeletal Class II High Angle with Mandibular Retrusion and Gummy Smile by Double-Jaw Surgery.

This report describes the treatment of severe skeletal Class II malocclusion in a young woman with a gummy smile and pronounced lower anterior facial height. Overjet and overbite were +12.0 mm and -1.0 mm, respectively. Cephalometric analysis revealed inferior positioning of the maxilla and severe mandibular retrusion with clockwise rotation. Both the upper and lower anterior teeth showed labial inclination. Based on a diagnosis of a skeletal Class II high angle with mandibular retrusion and a gummy smile, double-jaw orthognathic surgeries for upper and lower premolar extraction were chosen to gain ideal occlusion and an improvement in the esthetic facial profile. Le Fort I osteotomy was performed to move the anterior and posterior teeth upward by 4.0 mm and achieve mandibular counterclockwise rotation. Short lingual sagittal split ramus osteotomy was performed to move the mandible forward by 3.0 mm. As a result, normal overjet and overbite were achieved together with a straight profile and a good smile. After surgery, electromyographic evaluation of anterior temporal muscle activity showed an improvement in the percentage overlapping coefficient value (a symmetric index of bilateral muscle activity) from 28.1% to 63.2% compared to at pre-treatment. The pattern of jaw movement also showed an improvement. These results suggest that orthognathic surgery in skeletal Class II cases can improve not only malocclusion and the skeletal relationship of the jaws, but also masticatory function and jaw movement.

Imipramine prevents Porphyromonas gingivalis lipopolysaccharide-induced microglial neurotoxicity.

Porphyromonas gingivalis (P. gingivalis) is a Gram-negative anaerobe involved in the pathogenesis of chronic periodontitis, including local inflammation of the oral cavity. However, periodontal disease has recently been identified as a significant factor in the pathogenesis of neural diseases, including Alzheimer's disease. A virulence factor, P. gingivalis-lipopolysaccharide (LPS-PG), is involved in pro-inflammatory responses, not only in peripheral tissues but also in the brain. In this study, we examined whether P. gingivalis-induced brain inflammation could be ameliorated by pharmacotherapy, using in vivo and in vitro studies. In an animal experiment, peripheral administration of LPS-PG induced inflammation in the hippocampus via microglial activation, which was inhibited by pre-treatment with the antidepressant imipramine. Similarly, LPS-PG-induced inflammation in MG-6 cells, a mouse microglial cell line, was inhibited by pre-treatment with imipramine, which caused imipramine-induced inhibition of NF-κB signaling. Culture media obtained from LPS-PG-treated MG-6 cells induced neuronal cell death in Neuro-2A cells, a mouse neuroblastoma cell line, which was prevented by pre-treatment of MG-6 cells with imipramine. These results indicate that imipramine inhibits LPS-PG-induced inflammatory responses in microglia and ameliorates periodontal disease-related neural damage.

Effects of high-frequency near infrared laser irradiation on experimental tooth movement-induced pain in rats.

Discomfort and dull pain are known side effects of orthodontic treatment. Pain is expected to be reduced by near-infrared (NIR) lasers; however, the mechanism underlying effects of short-pulse NIR lasers in the oral and maxillofacial area remains unclear. This study aimed to examine the effects of high-frequency NIR diode laser irradiation on pain during experimental tooth movement (ETM) on 120 J. NIR laser with 910 nm wavelength, 45 W maximum output power, 300 mW average output power, and 200 ns pulse width (Lumix 2; (Lumix 2; Fisioline, Verduno CN, Italy) was used for the experiment. A nickel-titanium-closed coil was used to apply a 50-gf force between the maxillary left-side first molar and incisor in 7-week-old Sprague-Dawley rats (280-300 g) to induce ETM. We measured facial-grooming frequency and vacuous chewing movement (VCM) period between laser-irradiation and ETM groups. We performed immunofluorescent histochemistry analysis to quantify levels of Iba-1, astrocytes, and c-fos protein-like immunoreactivity (Fos-IR) in the trigeminal spinal nucleus caudalis (Vc). Compared with the ETM group, the laser irradiation group had significantly decreased facial-grooming frequency (P = 0.0036), VCM period (P = 0.043), Fos-IR (P = 0.0028), Iba-1 levels (P = 0.0069), and glial fibrillary acidic protein (GFAP) levels (P = 0.0071). High-frequency NIR diode laser irradiation appears to have significant analgesic effects on ETM-induced pain, which involve inhibiting neuronal activity, microglia, and astrocytes, and it inhibits c-fos, Iba-1, and GFAP expression, reducing ETM-induced pain in rats. High-frequency NIR diode laser application could be applied to reduce pain during orthodontic tooth movement.

Masticatory Function Assessment of Adult Patients With Cleft Lip and Palate After Orthodontic Treatment.

OBJECTIVE: To determine whether orthodontically treated patients with cleft lip and palate (CLP) possess a different masticatory function than those of untreated patients with normal occlusion. DESIGN: Occlusal contact area, occlusal force, as well as masseter and anterior temporal muscular activity were measured during maximum voluntary clenching (MVC) tests. Mandibular left and right lateral movements during mastication were also assessed. To further elucidate the nature of masticatory function, especially to determine the rate of abnormal jaw movement patterns, a parametric error index (EI) was set. Finally, masticatory efficiency was evaluated with a glucose sensitive measuring device. PARTICIPANTS: Fifteen patients with CLP who had previously completed the orthodontic treatments required to achieve an acceptable and more harmonious occlusion accepted to volunteer in this study along with 21 untreated patients who already possessed a normal occlusion. RESULTS: Patients with CLP showed a significantly lower occlusal force, reduced occlusal contact area, and decreased masticatory efficiency as well as significantly higher EI value when compared with controls. However, there was no significant difference when analyzing muscle activity, although masticatory efficiency was significantly different between the 2 groups. Despite this result, the scores obtained by the patients with CLP in the masticatory efficiency tests were still in the normal range. CONCLUSIONS: Orthodontic treatment for adult patients with CLP provides a satisfactory result for the patients' masticatory ability albeit significantly less ideal compared with untreated patients with normal occlusion.

An Investigation of Tongue-Palatal Contact Changes in Patients With Skeletal Mandibular Lateral Deviation After Sagittal Split Ramus Osteotomy.

ABSTRACT: This study aimed to investigate the changes in tongue-palatal contact patterns in patients with mandibular lateral deviation by electropalatography (EPG) before and after sagittal split ramus osteotomy (SSRO). Ten mandibular asymmetry patients who underwent SSRO participated in the study. Tongue-palatal contact patterns for the production of /t/ and /s/ sounds were observed using EPG before surgery and 3 months after surgery, and the changes in EPG pattern were examined. The number of electrode contacts in the 2 vertical columns of the EPG plate was calculated both in the mandibular deviation side and the nondeviation side. The EPG patterns for /t/ and /s/ showed asymmetry before surgery but became normal after surgery. Before surgery, the number of electrode contacts in the 2 vertical columns in the mandibular deviation side was significantly lower than that in the nondeviation side and the normal participants during /t/ and /s/ articulation. However, the number of electrode contacts in the deviation side significantly increased after surgery. This study demonstrated that the tongue-palatal contact patterns for /t/ and /s/ articulation shifted to the direction of mandibular deviation and improved after SSRO.

Stem cell-derived conditioned media from human exfoliated deciduous teeth promote bone regeneration.

OBJECTIVES: Cleft lip and palate (CL/P) are common congenital orofacial anomalies. Autogenous iliac bone grafting closes alveolar cleft defects but requires surgical intervention. Mesenchymal stem cell culture supernatant can regenerate tissues via paracrine activity. However, little is known about the bone-regenerative effects of stem cells from human exfoliated deciduous teeth (SHED) and conditioned media (CM). Our aim was to address this. MATERIALS AND METHODS: Stem cells were isolated from primary tooth pulp and cultured. Defects were made in calvariae of immunodeficient mice and implanted with stem cell- or CM-containing atelocollagen. Regenerated bone was analysed by microcomputed tomography, haematoxylin-eosin and Masson's trichrome staining. Vascular endothelial growth factor, CD31 and CD34 expression were confirmed by immunohistochemistry, and the presence of several proteins and growth factors was verified in SHED-CM. RESULTS: Bone regeneration was enhanced in defects treated with stem cells and CM compared to that in controls 8 weeks after transplantation. Mature bone formation and angiogenesis were confirmed with CM but not with stem cells or in controls. Secretome analysis using multiple cytokine assays revealed that SHED-CM contained tissue-regenerating factors with roles in angiogenesis and osteogenesis. CONCLUSION: CM non-invasively regenerate bone and might be effective to reconstruct alveolar clefts in CL/P patients.

Examination of the effect of combined use of Er:YAG laser irradiation and mechanical force loading on bone metabolism using primary human gingival fibroblasts.

Prolonged treatment and painful tooth movement are major problems for patients undergoing orthodontic treatment. Accelerating the movement of teeth leads to shortening of the treatment period, so various studies on the movement of teeth have been conducted in the field of orthodontics. In previous studies, we performed a fiber incision-like fiberotomy using an Er:YAG laser in rats and confirmed acceleration of tooth movement. Therefore, in this study, the effect of Er:YAG laser irradiation on human gingival fibroblasts was investigated in vitro. Human gingival fibroblasts (2.0 × 105 cells) were seeded in a 6-well plate and reached 80% confluence 24 h later. A control group not undergoing any irradiation and 3 groups undergoing laser irradiation at 0.6 W, 1.0 W, and 1.2 W were investigated. Laser irradiation was performed 24 h after cell seeding. The cells were then recovered 24 h later, and the cyclooxygenase-2 (COX-2), interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), bone morphogenetic protein-2 (BMP-2), and BMP-4 genes were confirmed by PCR. In addition, a control group not undergoing any procedures, a group undergoing only Er:YAG laser irradiation, a group undergoing only centrifugal loading, and a group undergoing both Er:YAG laser irradiation and centrifugal force loading were investigated. After 24 h, cells were collected and PCR was performed. Twenty-four hours after laser irradiation, gene expressions were examined by quantitative RT-PCR, which showed that the gene expressions of COX-2, IL-1ß, TNF-α, BMP-2, and BMP-4 increased depending on the amount of irradiation energy, with the largest value at 1.2 W. Gene expressions of COX-2, IL-1ß, TNF-α, BMP-2, and BMP-4 were significantly higher in the laser with centrifugal load group than in the load group. These results suggest that genes related to bone metabolism are activated in human gingival fibroblasts when mechanical stimulation and laser irradiation are combined. This helps to elucidate the effects of Er:YAG laser irradiation during tooth movement.

Bone Regeneration in a Canine Model of Artificial Jaw Cleft Using Bone Marrow-Derived Mesenchymal Stem Cells and Carbonate Hydroxyapatite Carrier.

OBJECTIVE: Cleft lip and palate (CLP) is a common anomaly of the orofacial region. Mesenchymal stem cell (MSC) transplantation has been a focus of regenerative medicine, and its application to the repair of bone defects in patients with CLP is highly anticipated. This study investigated the potential for using MSCs to regenerate bone in a jaw cleft as well as the survival of transplanted MSCs using a canine model of CLP. DESIGN: Mesenchymal stem cells collected from the bone marrow of beagle dogs were transplanted along with carbonate hydroxyapatite into jaw clefts in beagle dogs. Mesenchymal stem cells labeled with fluorescent silica nanoparticles were also transplanted, and a histological analysis was performed 3 months later to evaluate MSC survival. RESULTS: Carbonate hydroxyapatite regeneration into bone was enhanced by cotransplantation of MSCs. The survival rate of MSCs transplanted after 3 months was 5.7%. CONCLUSIONS: Transplanted MSCs promote bone regeneration, although their survival rate is low.

Comparative characterization of stem cells from human exfoliated deciduous teeth, dental pulp, and bone marrow-derived mesenchymal stem cells.

OBJECTIVES: Mesenchymal stem cells (MSCs) are used clinically in tissue engineering and regenerative medicine. The proliferation and osteogenic differentiation potential of MSCs vary according to factors such as tissue source and cell population heterogeneity. Dental tissue has received attention as an easily accessible source of high-quality stem cells. In this study, we compared the in vitro characteristics of dental pulp stem cells from deciduous teeth (SHED), human dental pulp stem cells (hDPSCs), and human bone marrow mesenchymal stem cells (hBMSCs). MATERIALS AND METHODS: SEHD and hDPSCs were isolated from dental pulp and analyzed in comparison with human bone marrow (hBM)MSCs. Proliferative capacity of cultured cells was analyzed using a bromodeoxyuridine immunoassay and cell counting. Alkaline phosphatase (ALP) levels were monitored to assess osteogenic differentiation. Mineralization was evaluated by alizarin red staining. Levels of bone marker mRNA were examined by real-time PCR analysis. RESULTS: SHED were highly proliferative compared with hDPSCs and hBMSCs. SHED, hDPSCs, and hBMSCs exhibited dark alizarin red staining on day 21 after induction of osteogenic differentiation, and staining of hBMSCs was significantly higher than that of SHED and hDPSCs by spectrophotometry. ALP staining was stronger in hBMSCs compared with SHED and hDPSCs, and ALP activity was significantly higher in hBMSCs compared with SHED or hDPSCs. SHED showed significantly higher expression of the Runx2 and ALP genes compared with hBMSCs, based on real-time PCR analysis. In bFGF, SHED showed significantly higher expression of the basic fibroblast growth factor (bFGF) gene compared with hDPSCs and hBMSCs. CONCLUSION: SHED exhibited higher proliferative activity and levels of bFGF and BMP-2 gene expression compared with BMMSCs and DPSCs. The ease of harvesting cells and ability to avoid invasive surgical procedures suggest that SHED may be a useful cell source for application in bone regeneration treatments.

Comparison of the bone regeneration ability between stem cells from human exfoliated deciduous teeth, human dental pulp stem cells and human bone marrow mesenchymal stem cells.

Cleft lip and palate is the most common congenital anomaly in the orofacial region. Autogenous iliac bone graft, in general, has been employed for closing the bone defect at the alveolar cleft. However, such iliac bone graft provides patients with substantial surgical and psychological invasions. Consequently, development of a less invasive method has been highly anticipated. Stem cells from human exfoliated deciduous teeth (SHED) are a major candidate for playing a significant role in tissue engineering and regenerative medicine. The aim of this study was to elucidate the nature of bone regeneration by SHED as compared to that of human dental pulp stem cells (hDPSCs) and bone marrow mesenchymal stem cells (hBMSCs). The stems cells derived from pulp tissues and bone marrow were transplanted with a polylactic-coglycolic acid barrier membrane as a scaffold, for use in bone regeneration in an artificial bone defect of 4 mm in diameter in the calvaria of immunodeficient mice. Three-dimensional analysis using micro CT and histological evaluation were performed. Degree of bone regeneration with SHED relative to the bone defect was almost equivalent to that with hDPSCs and hBMSCs 12 weeks after transplantation. The ratio of new bone formation relative to the pre-created bone defect was not significantly different among groups with SHED, hDPSCs and hBMSCs. In addition, as a result of histological evaluation, SHED produced the largest osteoid and widely distributed collagen fibers compared to hDPSCs and hBMSCs groups. Thus, SHED transplantation exerted bone regeneration ability sufficient for the repair of bone defect. The present study has demonstrated that SHED is one of the best candidate as a cell source for the reconstruction of alveolar cleft due to the bone regeneration ability with less surgical invasion.

Effect of high-frequency near-infrared diode laser irradiation on periodontal tissues during experimental tooth movement in rats.

BACKGROUND AND OBJECTIVES: Tooth movement during orthodontic treatment is associated with bone neoplasticity and bone resorption on the tension and pressure sides. Previous clinical studies have suggested that low-power laser irradiation can accelerate tooth movement during orthodontic treatment, although the underlying mechanism remains unclear. In this study, we used a high-frequency near-infrared diode laser that generates less heat and examined the histologic changes in periodontal tissue during experimental tooth movement with laser irradiation. METHODS: A nickel-titanium closed coil was mounted between the maxillary left side first molar and incisor of rats to model experimental tooth movement. The laser-irradiation and the control groups were set, and the amount of movement of the first molar on 7th and 14th days after the start of pulling of the first molar tooth on the maxillary left was measured by three-dimensional analysis of µCT. After tooth movement, tissue samples from the mesial and tension sides were collected, and successive horizontal sections were prepared and examined using hematoxylin-eosin and TRAP staining and immunohistochemical staining for RANKL, OPG, ALP, and proliferating cell nuclear antigen (PCNA). Changes in tissue temperature following laser irradiation were also examined. RESULTS: Laser irradiation significantly increased tooth movement compared with non-irradiated controls. Histologic staining of the pressure-side mesial root in laser-irradiated rats revealed enhanced RANKL expression and increased numbers of TRAP-positive cells compared with controls. By contrast, on the tension side, laser irradiation led to increased expression of ALP and PCNA. These data indicate that high-frequency near-infrared diode laser irradiation on the pressure side upregulates RANKL expression and accelerates osteoclast differentiation, facilitating bone resorption, whereas bone formation is induced on the tension side. CONCLUSION: This study demonstrates that high-frequency near-infrared diode laser irradiation of periodontal tissue leads to metabolic activation, which ultimately increases the rate of tooth movement. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

Accuracy of a three-dimensional dentition model digitized from an interocclusal record using a non-contact surface scanner.

OBJECTIVES: For orthodontic treatment, it is important to assess the dental morphology, as well as the position and inclination of teeth. The aim of this article was to develop an efficient and accurate method for the three-dimensional (3D) imaging of the maxillary and mandibular dental morphology by measuring interocclusal records using an optical scanner. MATERIALS AND METHODS: The occlusal and incisal morphology of participants was registered in the intercuspal position using a hydrophilic vinyl polysiloxane and digitized into 3D models using an optical scanner. Impressions were made of the maxilla and mandible in alginate materials in order to fabricate plaster models and created into 3D models using the optical scanner based on the principal triangulation method. The occlusal and incisal areas of the interocclusal records were retained. The buccal and lingual areas were added to these regions entirely by the 3D model of the plaster model. The accuracy of this method was evaluated for each tooth, with the dental cast 3D models used as controls. RESULTS: The 3D model created from the interocclusal record and the plaster model of the dental morphology was analysed in 3D software. The difference between the controls and the 3D models digitized from the interocclusal records was 0.068±0.048mm, demonstrating the accuracy of this method. LIMITATIONS: The presence of severe crowding may compromise the ability to separate each tooth and digitize the dental morphology. CONCLUSIONS: The digitization method in this study provides sufficient accuracy to visualize the dental morphology, as well as the position and inclination of these teeth.

Experimental Tooth Movement Into New Bone Area Regenerated by Use of Bone Marrow-Derived Mesenchymal Stem Cells.

OBJECTIVE: The aim of this study was to examine experimental tooth movement into regenerated bone in alveolar cleft with mesenchymal stem cells and a granulated carbonated hydroxyapatite scaffold. DESIGN: An artificial bone defect was created bilaterally in upper incisor regions of beagle dogs to simulate alveolar clefts in patients with cleft palate. The mesenchymal stem cells derived from the iliac bone marrow were cultured and transplanted with carbonated hydroxyapatite into the bone defect area. Carbonated hydroxyapatite alone was transplanted on the control side. Six months after the transplantation, multi-bracket appliances were attached to the lateral incisors and canines on both sides of the maxilla to exert an orthodontic force of 100 × g using an elastic chain. The distance between lateral incisor and canine was measured, and standardized x-ray images were taken every month. The tissue after tooth movement was evaluated by histological observation. RESULTS: The experimental tooth movement, accompanied by resorption of regenerated bone and new bone formation, was achieved on the experimental and control sides. Although there was no difference in the amount of tooth movement obtained on the experimental and control sides during the 6-month experimental period, the rate of tooth movement varied on the control side; whereas, the rate was consistent on the experimental side. Root resorption of the tooth was observed on the control side in one dog. CONCLUSION: It is suggested that mesenchymal/carbonated hydroxyapatite transplantation therapy has great potential as a new treatment modality for bone regeneration in patients with cleft palate.

Orthodontic Treatment of a Patient With Non-Syndromic Oligodontia and a Skeletal Class â ¢ Relationship: A Case Report and Six Years' Follow-Up.

Partial edentulism, characterized by the congenital absence of six or more permanent teeth (oligodontia), excluding the third molars, manifests with variable maxillofacial skeletal morphologies and occlusions, depending on the site and number of missing teeth, complicating treatment planning for occlusion and gain of function. Herein, we describe the case of a patient with seven non-syndromic congenitally missing permanent teeth (four in the maxillary and three in the mandibular dentition, excluding the third molars), who underwent orthodontic treatment, restorative procedures, and long-term follow-up for six years. The patient was an 18-year-old man presenting with a chief complaint of congenital absence of some permanent teeth and dental malalignment on the first visit. The mandibular right central incisor, bilateral mandibular second premolars, bilateral maxillary lateral incisors, and bilateral maxillary canines were congenitally absent, while the deciduous maxillary lateral incisors, maxillary canines, and mandibular second molars were over-retained bilaterally. Since the persisting deciduous teeth were remarkably well preserved, the patient was willing to retain them as far as possible; thus, we chose orthodontic and restorative treatment to preserve the deciduous teeth. Occlusion was established after the initiation of dynamic orthodontic treatment; restorative treatment with resin-based materials was performed for the bilateral maxillary deciduous incisors, bilateral maxillary deciduous canines, and bilateral mandibular second primary molars after bracket removal, and the retention phase of orthodontic treatment was initiated. At present, six years after establishing retention, the patient exhibits a good occlusal relationship. It is difficult to achieve complete space closure using orthodontic treatment alone in cases with six or more congenitally missing permanent teeth. In addition to considerations for age, esthetic issues due to missing permanent teeth, and maxillofacial skeletal morphology, it is necessary to preserve the deciduous teeth as much as possible and ensure multidisciplinary medical cooperation, including the transition to prosthodontic treatment during long-term follow-up.