Periodontal tissue regeneration by recombinant human collagen peptide granules applied with β-tricalcium phosphate fine particles

ObjectivesRecombinant human collagen peptide (RCP) is a recombinantly created xeno-free biomaterial enriched in arginine-glycine-aspartic acid sequences with good processability whose use for regenerative medicine applications is under investigation. The biocompatibility and osteogenic ability of RCP granules combined with β-tricalcium phosphate (TCP) submicron particles (β-TCP/RCP) were recently demonstrated. In the present study, β-TCP/RCP was implanted into experimental periodontal tissue defects created in beagles to investigate its regenerative effects.MethodsAn RCP solution was lyophilized, granulated, and thermally cross-linked into particles approximately 1 mm in diameter. β-TCP dispersion (1 wt%; 500 μL) was added to 100 mg of RCP granules to form β-TCP/RCP. A three-walled intrabony defect (5 mm × 3 mm × 4 mm) was created on the mesial side of the mandibular first molar and filled with β-TCP/RCP.ResultsA micro-computed tomography image analysis performed at 8 weeks postoperative showed a significantly greater amount of new bone after β-TCP/RCP grafting (2.2-fold, P < 0.05) than after no grafting. Histological findings showed that the transplanted β-TCP/RCP induced active bone-like tissue formation including tartaric acid-resistant acid phosphatase– and OCN-positive cells as well as bioabsorbability. Ankylosis did not occur, and periostin-positive periodontal ligament-like tissue formation was observed. Histological measurements performed at 8 weeks postoperative revealed that β-TCP/RCP implantation formed 1.7-fold more bone-like tissue and 2.1-fold more periodontal ligament-like tissue than the control condition and significantly suppressed gingival recession and epithelial downgrowth (P < 0.05).Conclusionsβ-TCP/RCP implantation promoted bone-like and periodontal ligament–like tissue formation, suggesting its efficacy as a periodontal tissue regenerative material.     

Effects of vitamin D deficiency on the rate of orthodontic tooth movement: An animal study

Bone remodeling and orthodontic tooth movement (OTM) are controlled by certain essential molecules, one of which is vitamin D. Increased levels of vitamin D have been associated with increased rates of OTM. The purpose of this study was to determine the effect of vitamin D deficiency on the rate of OTM, and to determine their association after applying orthodontic forces.Materials and MethodsWistar rats were divided into two groups: control group with average vitamin D levels and experimental group with induced vitamin D deficiency. Orthodontic appliances were fixed to initiate tooth movement. Distance between the reference teeth were measured in millimeters on day zero, and repeated every 7 days, till day 21.ResultsA significant difference within the experimental group was found; as well as within the control group, there was also no significant interaction between time and the type of group.ConclusionThe rate of Orthodontic tooth movement was not affected by induced vitamin D deficiency in rats.     

Tooth-level predictors of tooth loss and exposed bone after radiation therapy for head and neck cancer

BackgroundThe objective of this study was to identify tooth-level risk factors for use during preradiation dental care management to predict risk of tooth failure (tooth lost or declared hopeless) and exposed bone after radiation therapy (RT) for head and neck cancer (HNC).MethodsThe authors conducted a prospective observational multicenter cohort study of 572 patients receiving RT for HNC. Participants were examined by calibrated examiners before RT and then every 6 months until 2 years after RT. Analyses considered time to tooth failure and chance of exposed bone at a tooth location.ResultsThe following pre-RT characteristics predicted tooth failure within 2 years after RT: hopeless teeth not extracted pre-RT (hazard ratio [HR], 17.1; P < .0001), untreated caries (HR, 5.0; P < .0001), periodontal pocket 6 mm or greater (HR, 3.4; P = .001) or equaling 5 mm (HR, 2.2; P = .006), recession over 2 mm (HR, 2.8; P = .002), furcation score of 2 (HR, 3.3; P = .003), and any mobility (HR, 2.2; P = .008). The following pre-RT characteristics predicted occurrence of exposed bone at a tooth location: hopeless teeth not extracted before RT (risk ratio [RR], 18.7; P = .0002) and pocket depth 6 mm or greater (RR, 5.4; P = .003) or equaling 5 mm (RR, 4.7; P = .016). Participants with exposed bone at the site of a pre-RT dental extraction averaged 19.6 days between extraction and start of RT compared with 26.2 days for participants without exposed bone (P = .21).ConclusionsIndividual teeth with the risk factors identified in this study should be considered for extraction before RT for HNC, with adequate healing time before start of RT.Practical ImplicationsThe findings of this trial will facilitate evidence-based dental management of the care of patients receiving RT for HNC. This clinical trial was registered at Clinicaltrials.gov. The registration number is NCT02057510.     

Biochemical and X-ray micro-computed tomographic analyses of critical size bone defects grafted with autogenous bone and mercerized bacterial cellulose membranes salified with alendronate

ObjectivesThis study aimed to evaluate the repair of critical-sized bone defects grafted with autogenous bone and mercerized bacterial cellulose membranes (BCm) salified with alendronate (ALN).MethodsForty-eight male Wistar rats underwent surgery to create a 5 mm-diameter bone defect in the calvarium. The removed bone was particularized, regrafted into the defect, and covered by a BCm according to the group: control group (CG), simply mercerized BCm; group 1 (G1), negatively charged BCm (BCm-CM^-) salified with ALN; and group 2 (G2), positively charged BCm (BCm-DEAE⁺) salified with ALN. Serum samples were collected preoperatively and before euthanasia to analyze osteoprotegerin (OPG), parathyroid hormone (PTH), sclerostin (SOST), and fibroblast growth factor 23 (FGF23) levels. The animals were euthanized after 15 or 60 d. Calvaria were analyzed using quantitative microtomography (μCT).ResultsThere was an increased level of PTH in the CG compared to the G2 group, at day 60 (p = 0.019). When analyzing the same group over time, G1 presented an increased FGF23 level on days 15 and 60 (p < 0.05). CG presented an increase in PTH (p = 0.037) at day 60. The μCT analysis detected increased trabecular separation on day 15 in G2 compared to G1 (p = 0.040).ConclusionsSalification of ionized BCm with ALN had no direct effect on bone repair; however, BCm-CM^- increased the levels of FGF23 over time. BCm-DEAE⁺ decreased PTH levels compared to mercerized BCm. BCm-CM-salified with ALN-induced superior bone quality, with respect to trabecular separation, compared to BCm-DEAE⁺.     

Histological,immunohistochemical and radiographic evaluation of Amitriptyline administration on the periodontium of albino rats (An experimental study)

BackgroundAmitriptyline is a tricyclic antidepressant drug accustomed to treat depressive disorders. It recorded many side effects on different tissues.ObjectiveTo investigate reaction of Albino rats’ periodontium after oral administration of Amitriptyline histologically and radiographically.MethodsFourteen adult male albino rats (150–200 g) were divided into two groups, control and experimental. Rats of experimental group received 10 mg?kg?day of Amitriptyline hydrochloride by oral gavage for four weeks. Mandibles were prepared for hematoxylin and eosin (H&E) and anti-osteopontin (Anti-OPN) immunohistochemistry staining. Bone mineral density was measured in mandibular alveolar bone. Statistical analysis for Anti-OPN and relative Hounsfield unit value (HU value) was performed using independent-samples t-test.ResultsGingiva of experimental group showed epithelial degeneration with pyknotic nuclei and disintegration in lamina propria. Areas of separation in alveolar bone and degeneration of some regions in cementum were seen with apparent increase in periodontal ligament (PDL) thickness and its detachment from bone and cementum at some regions. Immunohistochemical examination of experimental group showed apparently increased immunopositivity in gingiva, cementocytes, osteocytes, cementum, bone matrices, fibroblasts and PDL fibers when compared to control group. Statistical analysis revealed insignificant difference of Anti-OPN area% in gingiva between both studied groups. While there was statistical significant increase of Anti-OPN area% in the other periodontium tissues and high statistical significant decrease of relative HU value in experimental group when compared to control.ConclusionsAmitriptyline has destructive effect on periodontal tissues and statistically increases the expression of Anti-OPN in all periodontal tissues except gingiva and decreases bone mineral density.     

Regeneration processes of alveolar bone and microvascular changes after the application of platelet-rich fibrin

ObjectivesPlatelet-rich fibrin (PRF) is a promising agent for bone regeneration (BR). Platelets contain several growth factors that promote angiogenesis and BR. In this study, we observed the morphology of alveolar BR.MethodsPRF (Advanced PRF: A-PRF) was prepared by extracting 10 mL of blood from each dog in a collection tube before tooth extraction. The samples were centrifuged at 200 × g for 8 min and incubated for 10 min to allow clotting. The alveolar socket on the dentition's right side was densely filled with PRF. The opposite side, which did not receive PRF, served as the control group. Different methods were used for specimen preparation and observation. Sections stained with hematoxylin and eosin were observed under a light microscope. Bone specimens were observed using stereoscopic microscopy. The resin cast models were examined using a scanning electron microscope. Moreover, bone formation ratio and height were measured.ResultsFourteen days postoperatively, angiogenesis and bone deposition were more advanced in the PRF group than in the control group. Thirty days postoperatively, both groups developed porous bone. In the PRF group, new bone trabeculae (BT) and a network of blood vessels were formed in the bone marrow. Ninety days postoperatively, the resin cast showed a normal bone structure with BT and bone marrow. Thick BT were observed in the PRF group.ConclusionsGrowth factors in PRF stimulate microcirculation and promote angiogenesis and bone deposition. The benefits of PRF include safety and increased bone formation.     

Time-lapse between periodontal regeneration surgery and root canal therapy in sever combined periodontal-endodontic lesions

ObjectiveThe purpose of this study was to evaluate the time-lapse of periodontal regeneration surgery of combined periodontal-endodontic lesions (PEL) after root canal therapy (RCT) to guide the clinical treatment.Methods26 patients (28 teeth) with severe combined PEL were equally divided into 4 groups (n = 7); the control group included patients who underwent periodontal regeneration surgery with no prior RCT and the remaining three experimental groups including patients who received periodontal regeneration surgery post-RCT either immediately or after 3 and 6 months. The probing depth, clinical attachment loss, and periodontal bone density were measured before or after 3, 6, and 12 months post-RCT, respectively.ResultsPeriodontal regeneration surgery could improve the PD (Probing Depth), CAL (Clinical Attachment Loss), BD (Bone Mineral Density) values irrespective of whether the RCT was performed within 12 months or not. However, obviously improved PD, CAL and BD were observed when surgery was performed post-RCT. The time lapse between RCT and periodontal regeneration surgery had no obvious effects on the periodontal index in 3 months after the surgery. Moreover, these periodontal indexes tend to stabilize in 3 to 6 months after the surgery with no significant differences.ConclusionAlthough there were no obvious impacts of time lapse between RCT and periodontal regeneration surgery on the severe PEL, an earlier periodontal surgery might contribute to the healing of periodontal lesions.     

The influence of periodontal status and serum biomarkers on salivary leptin levels in systemic lupus erythematosus patients

ObjectiveThis study aimed to investigate the influence of periodontal status, clinical data, and serum markers on salivary leptin levels in patients with systemic lupus erythematosus (SLE).MethodsA case–control study was conducted with 38 patients with SLE and 29 healthy controls. Periodontal data included periodontal probing depth (PPD), clinical attachment level (CAL), and gingival bleeding on probing (BOP). Stimulated saliva samples were collected to analyze salivary leptin levels. Clinical and serum data were collected from the SLE group. Statistical analysis included the t-test, Mann–Whitney test, Spearman correlation coefficient, and a structural equation model.ResultsThe SLE group had a lower salivary leptin level than the control group (P = 0.002). The model revealed that SLE had an inverse and independent effect on salivary leptin (standardized estimate =  ? 0.289, P = 0.023). Moreover, salivary leptin level negatively correlated with the serum levels of triglyceride, creatinine, and leukocytes, positively correlated with the serum total cholesterol, but was not significantly correlated with the periodontal status.ConclusionThese findings suggest that patients with SLE have a lower salivary leptin level. In addition, the level of salivary leptin does not appear to be related to periodontal status in patients with SLE.     

Biological modification of tooth surface by laser-based apatite coating techniques

BackgroundDevelopment of new clinical regenerative procedures is needed for the reconstruction of the connective tissue attachment lost to periodontal disease. Apatite coating on the affected root surfaces could improve root surface biocompatibility and promote the reestablishment of connective tissue attachment.HighlightWe developed two novel techniques that use laser light for coating the tooth surface with apatite. In the laser-assisted biomimetic (LAB) process, a tooth substrate was placed in a supersaturated calcium phosphate solution and irradiated for 30 min with low-energy pulsed laser light. Due to the laser-assisted pseudo-biomineralization, a submicron-thick apatite film was created on the laser-irradiated tooth surface. Furthermore, we created a fluoride-incorporated apatite film on the tooth surface using the LAB process and demonstrated its antibacterial activity against Streptococcus mutans.In the laser-induced forward transfer with optical stamp (LIFTOP) process, a thin apatite film loaded with the cell-adhesion protein, fibronectin, was prepared beforehand as a raw material on the optical stamp (carbon- and polydimethylsiloxane-coated support) by a conventional biomimetic process. After irradiation with a single laser pulse, the film (microchip) was transferred onto a tooth substrate via laser ablation of the carbon sacrificial layer. The LIFTOP process requires only a short processing time and has a minimal heat effect on the film; thus, the film exhibits cell adhesion activity even after the LIFTOP process.ConclusionThe LAB and LIFTOP processes have the potential as novel tools for tooth surface modification in the treatment of periodontal disease.     

Conditioned-medium of stem cells from human exfoliated deciduous teeth prevent apoptosis of neural progenitors

PurposeThis study aimed to evaluate the neuroprotective ability of the conditioned medium of stem cells from human exfoliated deciduous teeth (CM-SHED) to prevent glutamate-induced apoptosis of neural progenitors.Materials and methodsNeural progenitors were isolated from two-day-old rat brains, and the conditioned medium was obtained from a mesenchymal stem cell SHED. Four groups were examined: neural progenitor cells cultured in neurobasal medium with (N + ) and without (N-) glutamate and glycine, and neural progenitor cells cultured in CM-SHED with (K + ) and without (K-) glutamate and glycine.ResultsThe expression of GABA A1 receptor (GABAAR1) messenger RNA (mRNA) in neural progenitor measured by real-time quantitative PCR. GABA contents were measured by enzyme-linked immunosorbent assay, whereas the apoptosis markers caspase-3 and 7-aminoactinomycin D were analysed with a Muse® cell analyzer. The viability of neural progenitor cells in the K + group (78.05 %) was higher than the control group N- (73.22 %) and lower in the N + group (68.90 %) than in the control group. The K + group showed the highest GABA content, which significantly differed from that in the other groups, whereas the lowest content was observed in the N + group. The expression level of GABAAR1 mRNA in the K + group was the highest compared to that in the other groups. CM-SHED potently protected the neural progenitors from apoptosis.ConclusionsCM-SHED may effectively prevent glutamate-induced apoptosis of neural progenitors.     

The effect of Rutin hydrate on Glucocorticoids induced osteoporosis in mandibular alveolar bone in Albino rats (Radiological,histological and histochemical study)

BackgroundGlucocorticoids are used in different conditions such as autoimmune disorders and organ transplantation and their administration is the most common cause of secondary osteoporosis. Rutin is a flavonoid found in many plants. Flavonoids are natural products with various therapeutic and biological effects.ObjectiveIs to investigate the effect of Rutin Hydrate as a form of Rutin on glucocorticoid induced osteoporosis in mandibular alveolar bone radiologically, histologically and histochemically.MethodsTwenty-one adult male Albino rats were randomly divided into three groups. Group I (control), group II (osteoporotic) and group III (Rutin Hydrate treated). In both group II and III rats received 21 mg/kg of methylprednisolone daily for four weeks. Then group III received 50 mg/kg of rutin hydrate in distilled water daily for another four weeks. At the end of the experiment, mandibles were dissected for radiographic assessment, then processed for histological and histochemical examination and statistical analysis.ResultsRadiologically, administration of Rutin Hydrate was able to enhance bone density than osteoporotic group. Histological examination revealed preserved cortical bone thickness that had been statistically proved. Apparently normal sized marrow cavities, some plump osteoblasts and normal osteocytes were seen in group III. Histochemical examination showed statistical increase in the area percentage of newly formed collagen in group III than group II.ConclusionsRutin Hydrate was able to modify the radiological and histological picture of osteoporotic alveolar bone. This was achieved by the ability of Rutin Hydrate to increase bone density, preserve cortical plates thickness and enhance new collagen formation that was proved histochemically.     

Characterization and evaluation of ascorbic acid-induced cell sheet formation in human periodontal ligament stem cells: An in vitro study

ObjectivesPeriodontal ligament-derived stem cells (PDLSCs) are regarded as a viable option for periodontal regeneration using cell sheet technology. The objective of the present in vitro study was to characterize human PDLSCs based on their phenotypic and biological properties and to evaluate the ascorbic acid (AA or vitamin C)-induced cell sheet by analyzing the molecular markers.MethodsPDLSCs were established from premolars, and their morphology, viability, proliferation, phenotypic marker expression, and ability to differentiate into osteocytes and adipocytes were analyzed. PDLSCs were then induced to form cell sheets using 100 μM AA, and gene expression was examined by real-time polymerase chain reaction.ResultsPDLSCs showed fibroblastic morphology with >95% viability. The cells were highly proliferative and positive for surface antigens CD29, CD73, and CD90 but negative for CD34 and CD45. They were capable of differentiating into osteocytes and adipocytes. Induction with 100 μM AA transformed PDLSCs into two-to three-layered cell sheets. There was no significant upregulation in ALP and RUNX2 expression in the AA-induced cell sheet. However, the expression levels of late osteoblast differentiation marker (bone gamma-carboxy glutamate protein); cementogenic markers (cementum attachment protein and CP23), and genes encoding extracellular matrix (ECM) proteins [collagen type 1 alpha 1 and integrin beta 1) were higher in AA-induced cell sheets by PDLSCs.ConclusionsThe stimulating effect of AA on cell sheet formation by PDLSCs was confirmed by the expression of typical markers involved in osteogenesis/cementogenesis and ECM secretion, which makes this procedure a prospective option for periodontal tissue regeneration applications.     

Effect of the duration of a conditioned stimulus on component recognition in binary taste mixtures in rats

ObjectivesThe aim of this behavioral study was to investigate the duration of a conditioned stimulus (CS-duration) necessary for rats to recognize the components of a binary taste mixture in a conditioned taste aversion (CTA) paradigm as well as the relationship between CS-duration and their spontaneous recovery.MethodsThe experimental rats were categorized under conditioned and control groups and further divided into three groups according to the CS-duration: 10, 30, and 60 s. As the test stimuli, a mixture of 100 mM sucrose (S) + 30 μM quinine hydrochloride (Q) and its components were used.ResultsOn day 1 of the CTA test, the number of licks (NL) for S + Q and S in all conditioned groups was significantly lower than that of the control group presented with CS for 60 s (CON-60), which was the representative control group determined by the initial CTA test. For Q, there was no significant difference between NL of the CTA group presented with CS for 10 s and that of CON-60; however, NL in the other two CTA groups, i.e., CTA-30 and CTA-60, was significantly lower than that of CON-60. When the rats were presented with a shorter CS-duration, they showed spontaneous recovery earlier depending on the CS-duration.ConclusionsThese results suggest that rats can recognize a binary taste mixture and its components using a CS-duration of more than 30 s and that spontaneous recovery from CTA learning depends on the CS- duration.