Archives of Oral Biology

Editorial Board

2012-02-01

Dentine as a bioactive extracellular matrix

2012-02-01

Abstract: As a mineralised connective tissue, dentine is well adapted to its functional role as a major structural component of the tooth. Although similar in composition to bone, dentine matrix is not remodelled physiologically and traditionally, has been regarded as a rather inert tissue. Nevertheless, dentine–pulp demonstrates strong regenerative potential which allows it to respond to disease and traumatic injury. Such responses are strongly influenced by cell–matrix interactions and modified by disease processes, including infection and inflammation. The identification of many bioactive molecules bound within dentine matrix has allowed their potential involvement in regenerative and other tissue responses to be better understood and new opportunities to be recognised for novel clinical therapies.

Timing and sequence of emergence of permanent teeth in the Jordanian population

Ashraf I. Shaweesh — 2012-02-01

Abstract: Objectives: Population-specific standards of tooth emergence are essential resources for various fields of clinical and forensic dentistry. To date, such standards have not been provided for the Jordanian population. This study aimed at providing the timing and sequence of emergence of the permanent dentition in the Jordanian population.Methods and results: Using multistage clustered sampling, 1240 males and 1432 females aged 4–16 years from kindergartens and primary schools in the northern, middle and southern regions of Jordan were examined for emergence of permanent teeth. The subjects were classified into 1-year age groups. For a given tooth, “present” teeth were counted and expressed as a frequency relative to the total of subjects within a given age group. Using Probit regression (SPSS version 16), the median emergence age per tooth was calculated for the total sample and for both genders. No statistically significant differences were detected between sides. In addition, mandibular teeth were generally found to emerge earlier than the corresponding maxillary teeth. However, the difference in mandibular precedence was not statistically significant in all corresponding inter-maxillary tooth pairs. Furthermore, permanent teeth were found to emerge sooner in females than in males although the inter-gender differences were non-statistically significant for first molars and central incisors.Conclusions: The first standards of timing and sequence of permanent tooth emergence specific to the Jordanian population were provided and found to be consistent with those of Caucasian populations. These standards aid managing patients in paediatric dentistry, planning orthodontic therapy and forensic age estimation.

Mechanical and biological characterization of resin-modified glass-ionomer cement containing doxycycline hyclate

2012-02-01

Abstract: Objectives: To characterize the mechanical and biological properties of a resin-modified glass ionomer cement (RMGIC) containing doxycycline hyclate.Methods: The antibacterial effect of RMGIC containing 1.5, 3.0 and 4.5% doxycycline hyclate was assessed using two experiments – agar diffusion test for 24h and biofilm assay for 24h and 7 days – against some cariogenic bacteria. Briefly, base layers of BHI agar and 300μL of each inoculum were prepared in Petri dishes with 6 wells that were completely filled with materials. After 24h incubation, zones of bacterial growth inhibition were measured using a digital caliper. Biofilm assays were conducted using RMGIC specimens immersed in 24-well plates containing the inoculum in BHI broth. After 24h and 7 days, each specimen were removed, vortexed and the suspension diluted and inoculated in BHI plates for subsequent bacterial counting. Cytotoxicity tests used 50 specimens made in sterilized metal molds, including Vitrebond as positive control. Extracts from every specimen were applied on the MDPC-23 odontoblast-like cells for 24h. The MTT assay and SEM evaluation determined cell metabolism and morphology, respectively. 80 cylindrical specimens were made from the previously cited groups, and were submitted to testing with a universal testing machine (Instron 4411) using a crosshead speed of 1.0mm/min for compressive strength and 0.5mm/min for diametral tensile strength, respectively. Data from antibacterial and cytotoxic effects, and mechanical properties were submitted to appropriated statistical tests.Results: All tested groups showed growth inhibition of all tested strains (p<0.05) in 24h for both microbiological tests, but only 4.5% doxycycline have antibacterial effect after 7 days. None of doxycycline concentrations caused toxic effect to the MDPC-23 cells or presenting alterations to mechanical properties.Conclusion: The incorporation of up to 4.5% doxycycline hyclate into RMGIC inhibits important oral microorganisms, without modifying biological and mechanical characteristics of the dental material, suggesting a new alternative for the treatment of dental caries.

An in vitro comparison of dentifrice formulations in three distinct oral microbiotas

Ruth G. Ledder, Andrew J. McBain — 2012-02-01

Abstract: Objectives: In vitro biofilm models, representative of some aspects of nascent, supra-gingival plaques (Hydroxyapatite Disc Biofilm Models), developed supra-gingival plaques (Modified Drip-flow Biofilm Reactors) and sub-gingival plaques (Multiple Sorbarod Devices) were used to compare the antimicrobial effects of a triclosan-containing dentifrice with a stannous fluoride and zinc lactate combination.Design: Triplicate salivary biofilm microcosms were maintained for 2d (hydroxyapatite discs), 5d (Sorbarods) or up to 6d (drip flow reactors). Dentifrice slurries (10%, w/v) were added once to the discs and repeatedly to the Drip Flow Reactors and Sorbarods. Plaques were analysed by differential culture and gravimetrically.Results: Whilst both dentifrices were comparably effective at reducing viability and plaque accumulation in mature supragingival plaques, the triclosan dentifrice produced comparatively larger reductions in total streptococci and anaerobes in nascent plaques (p<0.05) and greater reductions in Gram-negative anaerobes and streptococci in subgingival plaques.Conclusions: We have used a multi-model approach to determine the effectiveness and specificity of dentifrices against compositionally distinct plaques. Whilst both formations reduced bacterial viability and plaque accumulation, their effects could be differentiated in nascent and deep plaques where the triclosan dentifrice caused larger viability reductions.

Low virulent oral Candida albicans strains isolated from smokers

2012-02-01

Abstract: It is widely accepted that tabagism is a predisposing factor to oral candidosis and cumulate data suggest that cigarette compounds may increase candidal virulence. To verify if enhanced virulence occurs in Candida albicans from chronic smokers, a cohort of 42 non-smokers and other of 58 smokers (all with excellent oral conditions and without signs of candidosis) were swabbed on tong dorsum and jugal mucosa. Results showed that oral candidal loads do not differ between smoker and non-smokers. Activities of secreted aspartyl-protease (Sap), phospholipase, chondroitinase, esterase–lipase, and haemolysin secretions were screened for thirty-two C. albicans isolates. There were detected significant increments in phospholipasic and chondroitinasic activities in isolates from non-smokers. For other virulence factors, no differences between both cohorts were achieved.

Oral ecosystem alterations in celiac children: A follow-up study

Silvia Mina, Carolina Riga, Ana Isabel Azcurra, Mabel Brunotto — 2012-02-01

Abstract: Objective: The aims of this work were (1) to assess the oral health status of children with celiac disease (CD) with or without compliance with a gluten-free diet and in non-celiac children in a follow-up study and (2) to identify oral ecosystem changes that could be used as non-invasive monitoring methods for CD patients. Study design: An 18-month follow-up study in children of both genders, who were 4–12 years old during the study period, was performed. Decayed-missing-filled in temporary (dmft) and permanent teeth (DMFT), enamel alterations, oral hygiene, and gingival index were measured. Oral smears were collected by brushing. Flow rate, calcium, phosphate, pH, buffer capacity, fluoride, and Ca/P ratio were measured in saliva. Salivary protein profiles were performed. Results: Most CD patients (80%) presented typical symptoms between 12 and 24 months old. Children with CD had a significantly low frequency of enamel alterations (30%) (p=0.0001). A high percentage of patients (63.15%) reported having had aphthous ulcers at several times. The celiac group showed significantly more polymorphonuclear neutrophils (PMNs) in smears (20% PMNs per area, p=0.0459) than the control group (0% PMNs per area) at baseline. In CD children, 90% of the samples that showed PMNs at baseline did not present them after 18 months. However, 10% of the smears of CD patients presented PMNs at the end of this study. Compliance with the gluten-free diet was controlled to detect the maintenance or worsening of signs and symptoms during the medical controls. Conclusions: The main differences amongst CD children who did or did not comply with a gluten-free diet and control children are the presence of PMNs in oral mucosa and protein salivary patterns; these findings could be considered as markers for CD, in conjunction with other signs and symptoms.

The expression of antioxidant enzymes in the gingivae of type 2 diabetics with chronic periodontitis

2012-02-01

Abstract: Objectives: There is controversial evidence regarding the levels of antioxidant molecules in type 2 diabetes periodontitis patients. Thus, the aim of the present study was to evaluate the gene expression of antioxidant enzymes in the gingival tissue of poorly and well-controlled type 2 diabetic subjects with chronic periodontitis (CP).Design: Gingival biopsies were harvested from systemically and periodontally healthy subjects (n=12), systemically healthy subjects with CP (n=15), well-controlled (n=8) and poorly controlled (n=14) diabetic subjects with CP. The messenger RNA (mRNA) levels of peroxiredoxin (PRDX) 1 and 2, catalase (CAT), glutathione peroxidase (GPX1) and superoxide dismutase (SOD) 1 and 2 were measured by quantitative polymerase chain reaction (qPCR).Results: The results showed that PRDX1 and GPX1 were up-regulated by periodontitis (p<0.05), independently of the glycaemic status, whilst PRDX2 and SOD2 genes were slightly influenced by periodontitis, but significantly induced when periodontitis was associated with DM, especially under a poor glycaemic control (p<0.05). Moreover, CAT and SOD1 expressions were not significantly influenced by any of these inflammatory disorders (p>0.05).Conclusion: In conclusion, both PRDX1 and GPX1 were overexpressed in CP whilst PRDX2 and SOD2 were up-regulated especially in the poorly controlled diabetic group with CP.

Periodontal healing by periodontal ligament cell sheets in a teeth replantation model

Yefang Zhou, Yusheng Li, Ling Mao, Hao Peng — 2012-02-01

Abstract: Objective: Successful transplantation of avulsed teeth is to restore the attachment and regenerate the periodontal support. Different strategies have been applied in treatment from modification of teeth storage, antibiotic usage to peridontium tissue replacement. We developed a novel periodontal ligament cell-sheet delivery system to apply on delayed replanted teeth in promoting periodontal healing in a canine model.Design: Autologous periodontal ligament (PDL) fibroblasts were isolated from extracted premolars of beagle dog. The cell-sheets were fabricated using normal culture dish after stimulation of extracellular matrix formation. Teeth were surgically extracted and attached soft tissues were removed. After root canal treatment, the root of teeth were wrapped by the PDL cell-sheets and replanted back to prior socket accordingly whilst teeth without cell sheets as a control. Eight weeks after surgery, the animals were sacrificed and decalcified specimens were prepared. Regeneration of periodontal tissue was evaluated through histology assay.Results: Multi-layered PDL cell-sheet could be attached on tooth root and most cells on sheet-tooth constructs were viable before replantation. Minimum clinical signs of inflammation were observed in experiment. PDL cell-sheets group show significant higher occurrence of favourable healing (88.4%) than control group with low healing (5.3%). Periodontal ligament and cememtum tissue regeneration was observed in the experimental group, and the regenerated tissues showed high collagen type III, type I and fibronectin expression.Conclusion: The periodontal ligament cell-sheets fabricated through normal cell culture dish has a potential for regeneration of periodontal ligament and may become a novel therapy for avulsed teeth replantation.

Effects of biglycan on physico-chemical properties of ligament-mineralized tissue attachment sites

R. Chiu, W. Li, R.P. Herber, S.J. Marshall, M. Young, S.P. Ho — 2012-02-01

Abstract: Matrix proteoglycans define matrix structure, mineralization, and resulting biomechanics of tissues and their attachment sites.Objective: We therefore investigated physical and (bio)chemical differences in enamel and periodontal tissues/attachment sites from mice that lack a specific nanoscale small leucine-rich proteoglycan (SLRPs) named biglycan (BGN).Design: Experimental groups consisted of N=4, biglycan knockout (BGNKO) and N=5 wildtype (WT) 8-week-old, male C3H mice. Morphology, histochemical and mechanical analyses were performed through micro X-ray computed tomography (Micro XCT™), immunohistochemistry, and microindentation. Unless mentioned otherwise, all differences between BGNKO and WT were demonstrated to be statistically significant through Student's t-tests with a 95% confidence interval (P≤0.05).Results: Histomorphometry performed by using Micro XCT™ images indicated significantly higher BGNKO-enamel (0.46±0.03mm3) and BGNKO-root (1.81±0.10mm3) volumes compared to WT-enamel (0.37±0.02mm3) and WT-root (1.65±0.07mm3). BGNKO tooth size was relatively larger than WT mice, with no significant difference between skull sizes. Immunohistochemistry indicated BGN expression in the periodontal ligament (PDL), alveolar bone (AB), at the bone–PDL and cementum–PDL attachment sites in WT mice. Deeper AB resorption pits within interdental region of BGNKO specimens compared to WT resulting in significant differences in PDL-space of BGNKO (93±13μm) and WT (74±11μm) were observed. Microhardness of BGNKO-enamel (2.46±0.60GPa) and BGNKO-AB (0.52±0.10GPa) was significantly lower than WT-enamel (2.67±0.60GPa) and WT-AB (0.54±0.10GPa).Conclusion: Results indicate that BGNKO-mice exhibit significant differences in tissue properties compared to WT-mice.

Matrix metalloproteinase 8 (MMP8) gene polymorphisms in chronic periodontitis

L. Izakovicova Holla, B. Hrdlickova, J. Vokurka, A. Fassmann — 2012-02-01

Abstract: Objective: Previous studies have suggested that some functional polymorphisms in the matrix metalloproteinase (MMPs) genes are associated with the risk of periodontal disease. However, to date no study has investigated MMP8 gene variants in relation to chronic periodontitis (CP). The aim of this study was to analyse polymorphisms in the MMP8 gene and their associations with microbial composition and clinical manifestation of CP.Design: A total of 619 unrelated Czech subjects were included in the present study. Two polymorphisms [−799C/T (rs11225395) and +17C/G (rs2155052)] in the MMP8 gene were studied in 341 patients with CP and 278 unrelated non-periodontitis controls. Both polymorphisms were detected using the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) methods. Subgingival bacterial colonisation (occurrence of bacteria in subgingival pockets and gingival sulci) was investigated by a commercial semiquantitative kit in selected subjects (N=169).Results: Our results showed no differences in the allele and genotype frequencies of the MMP8 −799C/T and +17C/G polymorphisms between patients with CP and controls (p>0.05). Nevertheless, the haplotype T(−799)/C(+17) was significantly more frequent in patients with CP than in controls [43.7% vs. 37.6%, p<0.05, OR=1.273 (95% CI: 1.013–1.601)]. Despite significant differences determined in the occurrence of periodontal bacteria between patients with CP and non-periodontitis controls (from p<0.000001 to p<0.05), no significant relationships between periodontal pathogens, MMP8 polymorphisms and CP were found (p>0.05).Conclusions: Although none of the investigated SNPs in the MMP8 gene was individually associated with periodontitis, specific haplotype showed association with clinical manifestation of chronic periodontitis in a Czech population.

Quantitation of SPLUNC1 in saliva with an xMAP particle-based antibody capture and detection immunoassay

2012-02-01

Abstract: The short palate lung and nasal epithelial clone 1 (SPLUNC1) protein may be differentially expressed in oral infections, oral inflammatory disorders, or oral malignancies and may be involved in innate immune responses in the oral cavity. However, the actual concentration of SPLUNC1 in saliva has not previously been determined. In this study, we determined the concentrations of SPLUNC1 in saliva using a particle-based antibody capture and detection immunoassay. A commercial goat anti-rhSPLUNC1 polyclonal antibody (AF1897) was linked to fluorescent polystyrene microspheres and used as the capture antibody. A commercial mouse IgG2b anti-rhSPLUNC1 monoclonal antibody (MAB1897) was biotinylated and used as the detection antibody. Western blot and 2-dimensional fluorescence difference gel electrophoresis (2-D DIGE) analysis of immunoprecipitated rhSPLUNC1 and SPLUNC1 from saliva were used to show that the capture AF1897 and detection MAB1897 antibodies both recognized SPLUNC1. Protein concentrations in saliva from 20 subjects ranged from 0.9 to 23.9mg/ml; SPLUNC1 concentrations ranged from 34.7ng/ml to 13.8μg/ml; and SPLUNC concentrations normalized per mg of total salivary protein ranged from 4.7ng/ml to 5.3μg/ml. These results show that SPLUNC1 is detected in saliva in a variety of concentrations. This immunoassay may prove to be useful in determining the concentration of SPLUNC1 in saliva for assessing its role in the pathogenesis of oral infections, oral inflammatory disorders, or oral malignancies.

Distinguishing patients with glossopyrosis from those with oropyrosis based upon clinical differences and differences in saliva and erythrocyte magnesium

Robert I. Henkin, Vasily Gouliouk, April Fordyce — 2012-02-01

Abstract: Objective: Burning mouth syndrome (BMS) is a complex of clinical symptoms defined by burning sensations in the oral cavity without observed oral pathology. Clinically two patient groups within BMS were distinguished, one with burning limited to the anterior tongue (glossopyrosis) and the other with burning in multiple mouth regions, including tongue, lips, palate, gums and cheeks (oropyrosis). Biochemical differences between these two groups could assist in distinguishing them.Design: Eighty-three patients with BMS, 47 with oropyrosis and 31 with glossopyrosis were studied. Measurements of zinc, copper, magnesium and calcium in blood plasma, erythrocytes and parotid saliva were obtained in patients and in normal subjects and mean levels were compared.Results: Clinical history differentiated patients into categories of oropyrosis and glossopyrosis. Erythrocyte and saliva levels of magnesium were significantly lower in patients with glossopyrosis than in patients with oropyrosis or in normal volunteers whereas levels of zinc and calcium were similar.Conclusions: These data suggest that patients with glossopyrosis not only differ clinically from those with oropyrosis but also exhibit magnesium deficiency as manifested by lower than normal magnesium levels in saliva and erythrocytes. Lingual burning in patients with glossopyrosis is consistent with hyperalgesia and neurogenic inflammation observed in patients and animals with magnesium deficiency and in magnesium deficient tissues. These results suggest a possible biochemical mechanism for pyrosis in patients with glossopyrosis.