Periodontal tissue, especially the alveolar bone, are closely associated with the progress and efficacy of orthodontic treatment. Prior to and during orthodontic treatment, dentists should fully evaluate the status of periodontal hard tissues to prevent clinical problems. This article aims to discuss bone issues associated with orthodontic treatment, including gingival papilla absence, alveolar bone insufficiency, excessive cortical resistance, and altered passive eruption, etc. The mechanism and prevention methods of these problems are also described.
Gingiva ; Periodontium

OBJECTIVE: Calprotectin, the heterdimer of S100A8 and S100A9, is the major cytoplasmic protein of neutrophils, which is also expressed or induced in gingival epithelial cells, activated mononuclear macrophages and vascular endothelial cells. Calprotectin is intimately associated with the initiation and progression of periodontitis, but the in vivo expression patterns of calprotectin in healthy and inflamed periodontal tissue are not fully understood. To observe the expression, distribution and cellular localization of calprotectin in the samples of healthy periodontal tissues and experimental periodontitis tissues of Beagles and to explore their relationship with periodontal inflammation and possible effect. METHODS: Experimental periodontitis model was established by ligation around the mandibular second molar of the Beagle dogs, while the contralateral teeth were healthy controls. Induction duration was 12 weeks, before the dogs were executed. Tissue specimens were demineralized and serial sections were made conventionally. The in vivo expression of calprotectin in the healthy and inflamed periodontal tissues were examined by immunohistochemistry. The in vitro expression of calprotectin in human primary gingival fibroblasts (GFs) and periodontal ligament (PDL) cells were detected by immunocytochemistry. RESULTS: Immunohistochemistry analysis indicated that calprotectin was expressed in gingival epithelial cells and infiltrated neutrophils in the healthy periodontium within the gingival epithelium, S100A8/A9 was most strongly expressed in the junctional epithelium, followed by surface epithelium, and least expressed in the sulcular epithelium. The S100A8/A9 expression levels were sharply defined at the junction between the junctional epithelium and the sulcular epithelium. In periodontal inflammatory lesions, the expression level of calprotectin in sulcular epithelium and junctional epithelium was up-regulated than that in the healthy gingival epithelium. Calprotectin was inducibly expressed in fibroblast-like cells in gingival connective tissue and periodontal ligament tissue, microvascular endothelial cells (ECs) and bone marrow fibroblasts under inflammatory conditions. Additionally, the expression of calprotectin in primary human GFs and PDL cells was confirmed by immunnocytochemistry staining. CONCLUSION Constitutively expressed in neutrophils and gingival epithelial cells, and calprotectin might maintain the homeostasis and integrity of periodontium. Inflammation-induced expression of calprotectin in GFs, PDL cells, microvascular ECs and bone marrow fibroblasts might process anti-microbial function and promote leukocytes transmigration to defend the host against the microorganisms.
Animals ; Dogs ; Endothelial Cells ; Epithelial Attachment ; Gingiva ; Humans ; Leukocyte L1 Antigen Complex ; Periodontium

The goal of periodontal treatment is regeneration of the periodontium. Bone graft and absorbable PLA/PGA membrane have been used for this purpose. In this study, 4x4mm 1-wall intrabony defects were surgically created bilaterally in the mandible of five male beagles. The control group went through a conventional flap operation, while the experimental group I was treated with absorbable PLA/PGA membranes only, group II was treated with absorbable membrane and calcium phosphate. The results are the following : 1. The defect height was 4.82+/-0.45mm in the control group, 4.93+/-0.79mm in the experimental I group, and 4.92+/-0.62mm in the experimental II group. There was no statistically significant difference among 3 groups(P<0.05). 2. The amount of junctional epithelium migration was 30.90+/-9.92% of the defect height in the control group, 39.16+/-7.51% in the experimental I group, and 38.68+/-12.22% in the experimental II group. There was no statistically significant difference among 3 groups(P<0.05). 3. The amount of connective tissue adhesion was 36.38+/-9.03% in the control group, 14.73+/-3.93% in experimental I group, and 27.87+/-9.70% experimental II group. Experimental group I was a statistically significantly different from control group(P<0.05). 4. The amount of new cementum regeneration was 32.92+/-10.51%, 50.04+/-7.61%, and 39.62+/-12.14% for the control, experimental I, and experimental II group respectively. Experimental group I was a statistically significantly different from control group(P<0.05). 5. The amount of new alveolar bone regeneration was 27.24+/-7.49%, 40.75+/-8.03%, and 36.47+/-15.11% for the control, experimental I, and experimental II group respectively. Experimental group I was a statistically significantly different from control group(P<0.05). The results suggest that the use of PLA/PGA membrane in 1-wall intrabony defect of beagle dogs may promote periodontal regeneration. Further studies are required to determine their regeneration effects.
Animals ; Bone Regeneration ; Calcium ; Connective Tissue ; Dental Cementum ; Dogs* ; Epithelial Attachment ; Humans ; Male ; Mandible ; Membranes* ; Periodontium ; Regeneration ; Transplants

BACKGROUND: Periodontitis is a destructive inflammatory disorder of the periodontium caused by the destruction of periodontal tissues namely the PDL, cementum, alveolar bone, and gingiva. Once these tissues are lost, the foremost goal of periodontal therapy is to regenerate the diseased tissues if possible to their original form, architecture, and function. Various regenerative procedures were employed and still a gap was found in achieving the goal. As stem cells are characterized by their ability to self-renew and differentiate to produce specialized cells, there could be a possibility of using them for regenerative therapy. Recently, dental tissues such as the PDL, the dental pulp and the tooth follicle have been recognized as readily available sources of adult stem cells. AIM: The aim was to identify the various sources and methodologies in isolation of stem cells from human oral cavity and its differentiation into various lineages using markers. MATERIALS AND METHODS: The electronic databases PUBMED, GOOGLE SCHOLAR, SCIENCE DIRECT, COCHRANE LIBRARY along with a complimentary manual search of all periodontics journal till the year 2016. Thirteen articles were selected on the basis of the inclusion criteria. Isolation of stem cells from oral cavity through various methods has been evaluated and similarly characterization to different lineages were tabulated as variables of interest. They included human in-vitro and ex-vivo studies. RESULTS: The results showed that PDLSC's and pulpal stem cells are the most common source from where stem cells were isolated. Each source has used different methodology in isolating the stem cells and it was found that STRO-1 was the commonly used marker in all the studies mentioned. CONCLUSIONS: The studies showed that there is no standard protocol existed in isolating the stem cells from different sources of oral cavity. Moreover, there was no standard marker or methodology used in characterization.
Adult Stem Cells ; Dental Cementum ; Dental Pulp ; Gingiva ; Humans ; Methods* ; Mouth* ; Periodontics ; Periodontitis ; Periodontium ; Stem Cells* ; Tooth

The periodontium is a topographically complex organ consisting of epithelial tissue, soft and mineralized tissues. Structures comprising the periodontium include the gingiva, periodontal ligament (PDL), cementum and the alveolar bone. The molecular mechanism of differentiation in PDL fibroblast cells remain unclear. Amino acid transporters play an important role in supplying nutrition to normal and cancer cells and for cell proliferation. Amino acid transport system L is a major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The system L is divided into two major subgroups, the L-type amino acid transporter 1 (LAT1) and the L-type amino acid transporter 2 (LAT2). In this study, the expression pattern of amino acid transport system L was, therefore, investigated in the differentiation of PDL fibroblast cells. To determine the expression level of amino acid transport system L participating in intracellular transport of amino acids in the differentiation of PDL fibroblast cells, it was examined by RT-PCR, observation of cell morphology, Alizaline red-S staining and uptake analysis after inducing experimental differentiation in PDL fibroblast cells isolated from mouse molar teeth. The results are as follows. 1. The LAT1 mRNA was expressed in the early stage of PDL fibroblast cell differentiation. This expression level was gradually reduced by differentiation-inducing time and it was not observed after the late stage. 2. The expression level of LAT2 mRNA was increased in time-dependent manner during differentiation induction of PDL fibroblast cells. 3. There was no changes in the expression level of 4F2hc mRNA, the cofactor of LAT1 and LAT2, during differentiation of PDL fibroblast cells. 4. The expression level of ALP mRNA was gradually increased and the expression level of Col I mRNA was decreased during differentiation of PDL fibroblast cells. 5. The L-leucine transport was reduced by time from the early stage to the late stage in PDL fibroblast cell differentiation. As the results, it is considered that among neutral amino acid transport system L in differentiation of PDL fibroblast cells, the LAT1 has a key role in cell proliferation in the early stage of cell differentiation and the LAT2 has an important role in the late stage of cell differentiation for providing cells with neutral amino acids including several essential amino acids.
Amino Acid Transport System L* ; Amino Acid Transport Systems ; Amino Acids ; Amino Acids, Essential ; Amino Acids, Neutral ; Animals ; Cell Differentiation ; Cell Proliferation ; Dental Cementum ; Fibroblasts* ; Gingiva ; Leucine ; Mice ; Molar ; Periodontal Ligament* ; Periodontium ; RNA, Messenger ; Tooth

Nitric oxide(NO) has been reported to be one of the mediators relating to bone remodelling. Nitric oxide is synthesized from L-arguinine by nitric oxide synthetase(NOS), which is largely divided into two groups. One group which is composed of NOS1 and NOS3, is dependent of calcium or calmodulin. The other consisted of NOS2, which is independent of calcium or calmodulin. NOS is thought to be a possible intermediate affecting in the course of tooth movement. This study was designed to evaluate the expression of nitrous oxide synthetase(NOS) in periodontal tissue during the experimental movement of rat incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for NOS2 and NOS3. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats), and 6 experimental groups(24 rats), to which 75g of force was applied, with helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 12 hours, 1, 4, 7, 14 and 28 days after force application, respectively. After that, the tissues of the control group and experimental groups were studied immunohistochemically. The results were as follows: 1. In control group, the expression of NOS3 was rare in gingiva, dentin, periodontal ligament and alveolar bone, and was mild in the capillaries of pulp and intermaxillary suture. And the expression of NOS2 showed similar pattern to that of NOS3. 2. There were no differences in the expression of NOS2 or NOS3 in dentin, gingiva, cementum, cementoblast and odontoblast, between control and experimental groups, regardless of the duration of the force application. 3. The expression of NOS3 began to increase at 4 days and showed to the highest degree at 7 days after force application, in the apical region of pressure side of periodontal ligament in experimental groups. 4. The expression of NOS3 in alveolar bone was rare until 7 days, after which it increased to mild degree at 14 days through 28 days in experimental group. But there was no difference between pressure and tension side of periodontal ligament. 5. The expression of NOS2 in periodontal ligament was mild from 7 days after force application, regardless of the side of periodontium, which was generally more evident than that of NOS3 . 6. The expression of NOS2 in alveolar bone increased to mild degree at 14 days after force application, and it was evident in osteoblasts, osteoclasts and osteocytes. And the expression of NOS2 was little more stronger in the tension side than that of pressure side of alveolar bone.
Animals ; Calcium ; Calmodulin ; Capillaries ; Dental Cementum ; Dentin ; Gingiva ; Incisor ; Nitric Oxide Synthase* ; Nitric Oxide* ; Nitrous Oxide ; Odontoblasts ; Osteoblasts ; Osteoclasts ; Osteocytes ; Periodontal Ligament ; Periodontium ; Rats* ; Rats, Sprague-Dawley ; Streptavidin ; Sutures ; Tooth Movement* ; Tooth*

The aim of this study was to understand the roles of Sonic Hedgehog (SHH) signaling during tooth root and periodontium formation. In this study, we generated the dental mesenchyme-specific Smoothened (Smo) activated/inactivated mice with the activity of Cre recombinase under the control of osteocalcin promoter.In the Smo activated mutant molar sections at the postnatal 28 days, we found extremely thin root dentin and widened pulp chamber. Picrosirius red staining showed loosely arranged fibers in the periodontal space and decreased cellular cementum with some root resorption. Immunohistochemical staining showed less localization of matrix proteins such as Bsp, Dmp1, Pstn, and Ank in the cementum, periodontal ligament, and/or cementoblast.In the Smo inactivated mutant mouse, there was not any remarkable differences in the localization of these matrix proteins compared with the wild type. These findings suggest that adequate suppressing regulation of SHH signaling is required in the development of tooth root and periodontium.
Animals ; Dental Cementum ; Dental Pulp Cavity ; Dentin ; Hedgehogs ; Mice ; Molar ; Osteocalcin ; Periodontal Ligament ; Periodontium ; Recombinases ; Root Resorption ; Tooth Root ; Tooth

OBJECTIVETo fabricate the bio-implant supported by regenerated periodontal tissue utilizing periodontal ligament cells (PDLC)-bone marrow stromal cells (BMSC) sheet and natural root.

METHODSPremolars of 2 beagle dogs were extracted to prepare the implanted area. Autologous tooth roots were carved into cylinders. PDLC and BMSC separated from beagle dogs were cultured into cell sheets in medium. Tooth roots were wrapped by one type of cell sheets or both to fabricate bio-implant and divided into four groups, tooth roots were wrapped by PDLC sheets and BMSC sheets successively (2 samples each dog), tooth roots were wrapped by PDLC sheets alone (2 samples each dog), tooth roots were wrapped by BMSC sheet alone (2 samples each dog), tooth roots without cell sheet (1 sample each dog). The implants were implanted into the mandibles. The mandibles were dissected 12 weeks later, sliced and stained by HE and Masson dyes for histological examination.

RESULTSIn the PDLC cell sheet/root implants, histological examination revealed that new periodontal-like tissue including cementum, periodontium and alveolar bone was regenerated.In the BMSC implants, tooth ankylosis was observed.

CONCLUSIONSPDLC sheet and natural root can be used to fabricate bio-implant. PDLC sheet could promote periodontal regeneration.

Animals ; Bicuspid ; Dental Cementum ; Dogs ; Guided Tissue Regeneration, Periodontal ; Mesenchymal Stromal Cells ; Periodontal Ligament ; cytology ; Periodontium ; Regeneration ; Tooth Root

PURPOSE: The purpose of this animal study was to perform a histological and histomorphometric analysis in order to elucidate the effect of fibroblast growth factor-2 (FGF-2) on injured periodontal ligament (PDL) and cementum after tooth replantation in dogs. METHODS: The roots of 36 mandibular premolars from six mongrel dogs were used in this study. The roots were randomly divided into three groups: (1) a positive control group (n=12), in which the PDL was retained; (2) a negative control group (n=12), in which the PDL and the cementum between the notches were removed; and (3) an experimental group (n=12), in which the PDL and the cementum between the notches were removed and the roots were soaked in an FGF-2 solution (30 microg/0.1 mL). After treating the root surfaces, the extracted roots were replanted into extraction sockets. The animals were sacrificed four and eight weeks after surgery for histologic and histomorphometric evaluation. RESULTS: At four and eight weeks, normal PDLs covered the roots in the positive control group. In the negative control group, most replanted roots showed signs of replacement resorption. In the experimental group, new PDL-like tissue and cementum-like tissue were observed to partially occupy the region between the root surfaces and the newly formed bone. Histomorphometric analysis showed that the mean length of the newly formed cementum-like tissue on the roots treated with FGF-2 was significantly greater than that of the tissue on the roots in the negative control group (four weeks, P=0.008; eight weeks, P=0.042). However, no significant differences were observed between the roots treated with FGF-2 and the negative control roots with respect to newly formed PDL-like tissue. CONCLUSIONS: The results of this study suggest that use of FGF-2 on injured root surfaces promotes cementogenesis after tooth replacement in dogs.
Animals ; Bicuspid ; Cementogenesis ; Dental Cementum* ; Dogs* ; Fibroblast Growth Factor 2 ; Fibroblast Growth Factors* ; Periodontal Ligament* ; Periodontium ; Regeneration ; Tooth ; Tooth Replantation*

OBJECTIVE: Periodontal ligament fibroblasts have an ectomesenchymal origin and are thought to play a crucial role for not only homeostasis of periodontal tissues but also bone remodeling, wound healing and regeneration of tissues. Recently, it has been reported that UNC-50 is not expressed in gingival fibroblasts but in PDL fibroblasts. The purpose of this study was to examine the expression of UNC-50 and osteocalcin in the periodontium after application of intermittent force. METHODS: Twelve rats had 40 grams of mesially-directed force applied at the upper molar for 1 hour/day. Four rats were sacrificed at 1, 3 and 5 days. Immunohistochemical localization of UNC-50 and osteocalcin antibody was carried out. The results showed apposition of new cellular cementum and a slight increase in periodontal space at the tension side. RESULTS: Strong UNC-50 expression was observed in the differentiating cementoblasts close to PDL fibroblasts in the tension side whereas it was barely expressed at the compression side. Expression was strong at day 3, and decreased at day 5. Osteocalcin immunoreactivity expression was strong in differentiating cementoblasts at the tension side. CONCLUSION: It can be suggested that UNC-50 is related to the differentiation of cementoblasts, and may be responsible for the molecular event in PDL cells under mechanical stress.
Animals ; Bone Remodeling ; Dental Cementum ; DNA* ; Fibroblasts ; Homeostasis ; Molar ; Osteocalcin ; Periodontal Ligament ; Periodontium ; Rats* ; Regeneration ; Stress, Mechanical ; Wound Healing