Changes In Periodontal Ligament Research Articles

Periodontal ligament and alveolar bone remodeling during long orthodontic tooth movement analyzed by a novel user-independent 3D-methodology

The structural process of bone and periodontal ligament (PDL) remodeling during long-term orthodontic tooth movement (OTM) has not been satisfactorily described yet. Although the mechanism of bone changes in the directly affected alveolar bone has been deeply investigated, detailed knowledge about specific mechanism of PDL remodeling and its interaction with alveolar bone during OTM is missing. This work aims to provide an accurate and user-independent analysis of the alveolar bone and PDL remodeling following a prolonged OTM treatment in mice. Orthodontic forces were applied using a Ni–Ti coil-spring in a split-mouth mice model. After 5 weeks both sides of maxillae were scanned by high-resolution micro-CT. Following a precise tooth movement estimation, an extensive 3D analysis of the alveolar bone adjacent to the first molar were performed to estimate the morphological and compositional parameters. Additionally, changes of PDL were characterized by using a novel 3D model approach. Bone loss and thinning, higher connectivity as well as lower bone mineral density were found in both studied regions. Also, a non-uniformly widened PDL with increased thickness was observed. The extended and novel methodology in this study provides a comprehensive insight about the alveolar bone and PDL remodeling process after a long-duration OTM.

Remodeling of the periodontal ligament and alveolar bone during axial tooth movement in mice with type 1 diabetes.

To observe the elongation of the axial tooth movement in the unopposed rodent molar model with type 1 diabetes mellitus and explore the pathological changes of periodontal ligament and alveolar bone, and their correlation with tooth axial movement. The 80 C57BL/6J mice were randomly divided into the streptozotocin(STZ)-injected group (n = 50) and the control group (n = 30). Mice in the streptozotocin(STZ)-injected group were injected intraperitoneal with streptozotocin (STZ), and mice in the control group were given intraperitoneal injection of equal doses of sodium citrate buffer. Thirty mice were randomly selected from the successful models as the T1DM group. The right maxillary molar teeth of mice were extracted under anesthesia, and allowed mandibular molars to super-erupt. Mice were sacrificed at 0, 3, 6,9, and 12 days. Tooth elongation and bone mineral density (BMD) were evaluated by micro-CT analysis(0,and 12 days mice). Conventional HE staining, Masson staining and TRAP staining were used to observe the changes in periodontal tissue(0, 3, 6, 9, and 12 days mice). The expression differences of SPARC, FGF9, BMP4, NOGGIN, and type I collagen were analyzed by RT-qPCR. After 12 days of tooth extraction, our data showed significant super-eruption of mandibular mouse molars of the two groups. The amount of molar super-eruption in the T1DM group was 0.055mm( ± 0.014mm), and in the control group was 0.157( ± 0.017mm). The elongation of the T1DM mice was less than that of the control mice(P<0.001). It was observed that the osteoclasts and BMD increased gradually in both groups over time. Compared with the control group, the collagen arrangement was more disordered, the number of osteoclasts was higher (P<0.05), and the increase of bone mineral density was lower(2.180 ± 0.007g/cm3 vs. 2.204 ± 0.006g/cm3, P<0.001) in the T1DM group. The relative expression of SPARC, FGF9, BMP4, and type I collagen in the two groups increased with the extension of tooth extraction time while NOGGIN decreased. The relative expression of all of SPARC, FGF9, BMP4, and type I collagen in the T1DM group were significantly lower, and the expression of NOGGIN was higher than that in the control group (P<0.05). The axial tooth movement was inhibited in type 1 diabetic mice. The result may be associated with the changes of periodontal ligament osteoclastogenic effects and alveolar bone remodeling regulated by the extracellular matrix and osteogenesis-related factors.

The different irradiation parameters of carbon dioxide laser effects on periodontal ligament cells

Background/purpose: Photobiostimulation (PBS) can affect cellular functions. The objective of the present study was to evaluate the cellular changes in periodontal ligament (PDL) cells that received different carbon dioxide (CO2) laser irradiation parameters under negative pressure culture. Materials and methodsThe negative pressure-cultured PDL cells on normal medium and differentiation medium were subjected to continuous irradiation with a CO2 laser at an energy density of 5 J/cm2 or 10 J/cm2. The irradiated PDL cells were harvested at Days 1, 5 and 7, and their viability was analyzed by the Presto Blue assay and the biologic markers alkaline phosphatase (ALP), bone sialopoietin (BSP), osteopontin (OPN), osteocalcin (OC), matrix metalloproteinase-3 (MMP-3) collagen I (Col I) and cyclooxygenase-2 (COX-2) expression by reverse transcription-polymerase chain reaction (RT–PCR). ResultsThe PDL cell viability showed that the differentiation medium groups were higher than the normal culture groups. The cell morphologies were all expressed as spindle type. The inflammatory markers in the laser-irradiated groups were higher on the first day and decreased on the seventh day (P < 0.05). Osteogenesis markers were highly expressed at different time periods (P < 0.05). The Col I and OPN genes were highly expressed on the first day, and the Col I high expression lasted until the seventh day. The OC gene was highly expressed on the seventh day. The effects of PDL cultured in differential medium and normal medium were the same in the present study. ConclusionA low-dose CO2 laser continuously irradiating cultured PDL cells can induce osteogenesis and reduce cell inflammatory expression.

BBS7-SHH Signaling Activity Regulates Primary Cilia for Periodontal Homeostasis.

Objectives: Mechanical stimuli are essential for the maintenance of periodontal ligament (PDL) homeostasis. Although there are several studies on atrophic changes in PDL due to occlusal hypofunction, the underlying mechanism is still unknown. Here, we aimed to explore the changes of gene expression in occlusal hypofunctional PDL and elucidate the related role in maintaining the PDL homeostasis. Methods: To investigate the transcriptomic difference between control and hypofunctional PDL tissue from patients, RNA sequencing was performed on 34 human teeth. The atrophic changes in PDL were evaluated by histological analysis. The effect of the Bardet-Biedl syndrome 7 (BBS7) knockdown was evaluated by the RT-qPCR, Western blot, wound healing, and tubule formation assay. Results: We detected that the expression of BBS7 was downregulated in occlusal hypofunctional PDL through RNA sequencing. Dynamic changes, including the number of periodontal ligament cells, alignment of collagen fibers, diameter of blood vessels, appearance of primary cilia, and torturous oxytalan fibers, were observed following occlusal hypofunction. Furthermore, Sonic hedgehog signaling (Shh) activity was closely associated with BBS7 expression in PDL cells. In addition, the cell migration and angiogenesis were also suppressed by BBS7 knockdown in vitro. Conclusion: We suggest that BBS7 plays an essential role in maintaining Shh signaling activity for PDL homeostasis.

Non-invasive evaluation of periodontal ligament stiffness during orthodontic tooth movement.

To evaluate the longitudinal changes in periodontal ligament (PDL) stiffness during orthodontic tooth movement using the Advanced System for Implant Stability Testing (ASIST). ASIST measurements of maxillary canines that were actively retracted into an extraction space were collected approximately once per month for 12 adolescent female patients. The ASIST Stability Coefficient (ASC) values, which are directly related to PDL stiffness, were determined for each visit to examine longitudinal changes for individual canines as they were exposed to different forces (approximately 80 and 150 g) during retraction. The pattern of longitudinal changes in ASC was similar for both canines (regardless of the two force levels applied) in individual patients and across patients. All patients showed some decrease in ASC, with an average maximum reduction in stiffness of 73.4 ± 7.7%. Some recovery was observed for most patients; however, none of the patients had the PDL stiffness return to the pre-treatment value at the final measurement appointment which was some time close after space closure was completed. On average, the ASC value at the final measured visit was 48.1 ± 12.2% of the initial value. No measurements are available after removal of orthodontic appliances and during retention. The ASIST was able to detect changes in PDL stiffness during orthodontic treatment, providing some insight into the mechanical changes that occur at the tooth root interface.

Evaluation of radiomorphometric indices and bone findings on panoramic images in patients with scleroderma

The aim of this study was to make radiomorphometric measurements on panoramic images and evaluate the radiologic findings of bones and teeth in patients with scleroderma. Panoramic images of 49 patients with scleroderma and 51 healthy controls were assessed. Mandibular radiomorphometric indices, including mandibular cortical index (MCI), mental index (MI), panoramic mandibular index (PMI), gonial index (GI), and antegonial index (AI), were determined. Furthermore, mandibular osteolysis, changes of periodontal ligament (PDL) space and changes in the lamina dura were recorded for the scleroderma group. Statistically significant differences were found for MCI (P = .003), MI (P = .001), and PMI (P < .001) between the scleroderma and control groups, but not for GI or AI (P > .05). Widening of the PDL space (79.6%), thickening of the lamina dura (44.9%), limited mouth opening (71.4%), and osseous resorption of the mandible (8%) were detected in the scleroderma group. The radiomorphometric indices determined in the present study can be used on panoramic images to identify the existence of a porous structure in the mandibular cortical bone in patients with scleroderma. The most common prevalent oral radiographic manifestations of scleroderma were widening of the PDL space and of the lamina dura.

Micro-anatomical responses in periodontal complexes of mice to calibrated orthodontic forces on the crown.

Correlating mechanical forces with quantifiable physical changes in the dentoalveolar complex. Male 6-week C57BL/6 mice (N=3), micro X-ray-computed tomography; post-analysis software to extract physical changes in periodontal ligament (PDL)-space. Silicone-elastic bands were placed between maxillary molars for 1week, with the contralateral side as internal control. Average displacements between crowns and roots, and changes in PDL-spaces were evaluated by registering X-ray tomograms of experimental and control hemi-maxillae. Histology illustrated mineral formation and resorption-related events within narrowed and widened volumes of the PDL-space. 3D maps of changes in PDL-space between molars illustrated coronal and root displacements of 640μm and 180μm, respectively, compared to 70μm in controls. Orthodontic tooth movement (OTM) specimens exhibited an average net change of -20μm in narrowed and +30μm in widened PDL-spaces. Bone and cementum were affected by the force on molars, and primary cementum was more affected than secondary cementum. This novel approach illustrates the importance of 3D-imaging and analysing 3D alveolar socket subjected to OTM otherwise omitted by 2D micrographs.A measured force on the crown elicits a response related to narrowed and widened regions in the 3D complex. OTM that exceeds PDL-space can illicit biological responses that attempt to restore physiologic PDL-space via remodelling of the periodontium. Regenerated weaker bone due to aseptic inflammation caused by orthodontics could leave patients at a higher risk of bone loss or root resorption if they later develop periodontitis, a form of septic inflammation.

The influence of orthodontic treatment on dental pulp and periapical tissues

The pathogenesis of pulpal and periapical diseases is related with not only bacterial infection but also physicochemical irritations such as trauma and thermal changes. During orthodontic therapy, the application of orthodontic forces on teeth may produce a series of changes in periodontal ligament, alveolar bone and pulpo-dentinal complex. This article reviewed the influences of orthodontic therapy on dental pulp and periapical tissues.

Mechanical Loading Stimulates Expression of Collagen Cross-Linking Associated Enzymes in Periodontal Ligament.

Type I collagen, a major extracellular component of the periodontal ligament (PDL), is post-translationally modified by a series of specific enzymes. Among the collagen-modifying enzymes, lysyl oxidase (LOX) is essential to initiate collagen cross-linking and lysyl hydroxylases (LHs) to regulate the cross-linking pathways that are important for tissue specific mechanical properties. The purpose of this study was to investigate the effects of mechanical loading on the expression of collagen-modifying enzymes and subsequent tissue changes in PDL. Primary human PDL cells were subjected to mechanical loading in a 3D collagen gel, and gene expression and collagen component were analyzed. Wistar rats were subjected to excessive occlusal loading with or without intra-peritoneal injection of a LOX inhibitor, β-aminopropionitrile (BAPN). Upon mechanical loading, gene expression of LH2 and LOX was significantly elevated, while that of COL1A2 was not affected on hPDL-derived cells. The mechanical loading also elevated formation of collagen α-chain dimers in 3D culture. The numbers of LH2 and LOX positive cells in PDL were significantly increased in an excessive occlusal loading model. Notably, an increase of LH2-positive cells was observed only at the bone-side of PDL. Intensity of picrosirius red staining was increased by excessive occlusal loading, but significantly diminished by BAPN treatment. These results demonstrated that mechanical loading induced collagen maturation in PDL by up-regulating collagen-modifying enzymes and subsequent collagen cross-linking which are important for PDL tissue maintenance. J. Cell. Physiol. 231: 926-933, 2016. © 2015 Wiley Periodicals, Inc.

Micro-Raman spectroscopy for monitoring changes in periodontal ligaments and gingival crevicular fluid.

Micro-Raman Spectroscopy is an efficient method for analyzing biological specimens due to its sensitivity to subtle chemical and structural changes. The aim of this study was to use micro-Raman spectroscopy to analyze chemical and structural changes in periodontal ligament after orthodontic force application and in gingival crevicular fluid in presence of periodontal disease. The biopsy of periodontal ligament samples of premolars extracted for orthodontic reasons and the gingival crevicular fluid samples collected by using absorbent paper cones; were analyzed by micro-Raman spectroscopy. Changes of the secondary protein structure related to different times of orthodontic force application were reported; whereas an increase of carotene was revealed in patients affected by periodontal inflammation.

Florid Cemento-osseous Dysplasia: Report of Three Unusual Cases

ABSTRACT Florid cemento-osseous dysplasia (FLCOD) is a reactive process that involves tooth-bearing areas of the jaws. Reactive or dysplastic changes in periodontal ligament have been suggested as an etiologic factor. It usually affects females and is less frequently seen in Caucasians and Asians groups. Multiple sclerotic masses involving more than one quadrant are it is radiographic appearance. Because of its benign nature periodic recall is all things to do but in symptomatic cases surgical intervention may be required. How to cite this article Bagheri F, Taheri JB, Azimi S, Elmi Z. Florid Cemento-osseous Dysplasia: Report of Three Unusual Cases. Int J Experiment Dent Sci 2014;3(2):103-105.

Modificações no periodonto de ratos diabéticos após a movimentação ortodôntica

OBJETIVOS: o objetivo deste trabalho foi avaliar as modificações do ligamento periodontal de incisivos de ratos diabéticos submetidos a forças ortodônticas. MÉTODOS: vinte ratos machos Wistar (Rattus norvegicus) com 105 dias de idade foram empregados. Os ratos foram divididos em quatro grupos: C - animais normoglicêmicos não submetidos à movimentação dentária; CAO - animais normoglicêmicos submetidos à movimentação dentária; D - animais diabéticos não submetidos à movimentação dentária; DAO - animais diabéticos submetidos à movimentação dentária. Os animais permaneceram com o dispositivo de movimentação dentária por 5 dias. Foram avaliados o número de vasos sangüíneos e a espessura do ligamento periodontal nos terços cervical, médio e apical dos cortes histológicos. RESULTADOS E CONCLUSÕES: no lado de tensão, a movimentação dentária nos animais do grupo CAO resultou em um ligamento periodontal mais espesso (17,64% no terço apical, 39,28% no terço médio e 51,35% na região cervical), quando comparado ao grupo C (p &lt; 0,05 para os terços médio e cervical). No grupo DAO, o aumento da espessura do ligamento periodontal foi 50,55% (terço apical), 48,14% (terço médio) e 50% (terço cervical) maior que nos animais do grupo D (p &lt; 0,05). O número de vasos sanguíneos encontrados no ligamento periodontal não apresentou diferenças estatisticamente significantes quando todos os grupos foram comparados (p &gt; 0,05). Ainda no lado de tensão, foram observadas lacunas de reabsorção nos animais dos grupos CAO, D e DAO. O lado de pressão não foi examinado nesta fase do estudo.

Optical approach for monitoring the periodontal ligament changes induced by orthodontic forces around maxillary anterior teeth of white rats

Structural variations of the periodontal ligament (PDL) induced by orthodontic forces have been evaluated by optical coherence tomography (OCT) and compared to images obtained by conventional radiography. Here, two specially designed orthodontic appliances were installed on the maxillary anterior teeth of white rats for applying different magnitudes of orthodontic forces. Constant distraction force magnitudes of 0, 5, 10, and 30 gf were given to four respective rats over a period of 5 days. At the end of the treatment period, the rats were sacrificed and the maxillaries were extracted for X-ray and OCT imaging. The PDL variations, proportional to the force magnitude, were clearly indicated in the OCT measurements. The OCT images further showed that the ligament was torn for a constant orthodontic force of 30 gf. These results support the clinical dental application of OCT for monitoring the ligament changes during orthodontic procedures. The real-time imaging capability of OCT, together with its high resolution, has the potential to help dentists with in vivo orthodontic treatments in human subjects as well.

Neutrophil elastase is involved in the initial destruction of human periodontal ligament

It has been reported that noncollagenous proteins may provide mechanical strength to the periodontal ligament. Several proteolytic activities, including that of neutrophil elastase, are reported to increase significantly in periodontal disease. The aim of this study was to investigate the function of neutrophil elastase in the initial destruction of periodontal ligament at early stages of periodontal disease. The detection and identification of proteinases in chronic periodontitis and healthy periodontal ligament were examined by zymographic and zymo-Western analysis. The morphological changes of periodontal ligament, digested with or without authentic proteinases, were observed using scanning electron microscopy. Increases in neutrophil elastase, plasminogen, and matrix metalloproteinase-9 were detected in periodontal ligament from chronic periodontitis, compared with healthy periodontal ligament. Among these proteinases, only neutrophil elastase digested the intact noncollagenous proteins of periodontium. When human healthy periodontal ligament was directly digested by neutrophil elastase in an in vitro system, the morphological features were quite similar to that of the periodontal ligament in chronic periodontitis . In healthy periodontal ligament, the collagen fibrils are covered with noncollagenous proteins containing 110 kDa acidic glycoprotein, which was degraded initially by the neutrophil elastase. It was concluded that neutrophil elastase is involved in the degradation of noncollagenous protein-covered collagen fibrils in the early destructive stages of periodontal disease.

Morphologic Changes of Periodontal Ligament Induced by an Altered Diet ‐ Experimental Study

The periodontal ligament, a connective tissue attaches teeth to the surrounding alveolar bone with an important role in resisting to masticator oclusal dental forces and response to noxious stimuli. We used two groups of twenty Wistar male rats, four weeks old. The control group was maintained with no manipulation. The test was submitted to the administration of a diet very rich sucrose during four weeks. After this time the animals were sacrificed and the infra-coronal pulp of the first molar was observed under light microscopy. The areas of periodontal ligament (PL) and hard tissue (HT) was calculated and presented as a ratio (R): HT/PL. We found the following groups in the control group: median R, high R, low R, very low R and very high R. The percentage R cases in group I were: 0%VL; 10.00%L; 50.00%M; 20.00%H and 15.00%VH. The distribution in the group II was: 2.00 %VL; 22.00%L; 32.00%M; 32.00%H and 10.00%VH. We observed a large account of osteoclastic cells on periodontal ligament surrounding bony tissues. These findings suggest a role of diet on periodontal ligament’s health. It is also important to evaluate the impact of the diet composition in changes related to the inflammatory process.

Periodontal ligament changes in patients with progressive systemic sclerosis

Progressive systemic sclerosis (PSS) is a generalized collagen disease which has oral manifestations, including widening of the periodontal ligament (PDL) space. The purpose of this study was to measure the extent of thickening of the PDL space in a group of 26 patients with PSS and in a similar group of age and sex-matched control patients. The width of the PDL was measured from periapical radiographs at four sites around seven selected teeth for every patient. The mean PDL width was found to be larger in all the patients with PSS than in the control patients, around both anterior and posterior teeth. One third of the teeth of patients with PSS had PDL widths thicker than the range observed in the control patients. When average thickness of PDL widths for each patient is compared, at least 65% of the patients with PSS have mean PDL widths which are greater than the range for control patients. The increased thickness of the PDL space associated with PSS is more pronounced in posterior teeth than in anterior teeth.