Stimulated human whole saliva (WS) was used to study the dynamics of papain hydrolysis at defined pH, ionic strength, and temperature with the view of reducing an acquired pellicle. A quartz crystal microbalance with dissipation (QCM-D) was used to monitor the changes in frequency caused by enzyme hydrolysis of WS films, and the hydrolytic parameters were calculated using an empirical model. The morphological and conformational changes of the salivary films before and after enzymatic hydrolysis were characterized by atomic force microscopy (AFM) imaging and grazing-angle Fourier transform infrared (GA-FTIR ) spectra, respectively. The characteristics of papain hydrolysis of WS films were pH-, ionic strength-, and temperature-dependent. The WS films were partially removed by the action of papain, resulting in thinner and smoother surfaces. The infrared data suggested that hydrolysis-induced deformation did not occur on the remnants of salivary films. The processes of papain hydrolysis of WS films can be controlled by properly regulating pH, ionic strength, and temperature.

Amelogenin plays a key role in the formation of the highly mineralized structure of tooth enamel. During the secretory stage, amelogenin is cleaved gradually by a protease, matrix metalloproteinase-20 (MMP-20), releasing hydrophilic C-terminal peptides. In this study, the biophysical properties of synthetic C-terminal peptides (of 28, 17, and 11 residues), mimicking native peptides, were explored in vitro. A sudden decrease was observed in the zeta (ζ)-potential upon the addition of calcium or phosphates, which was also accompanied by an increased aggregation propensity of the peptides. Under most of the experimental conditions, the particle size increased at a pH 2–3 units higher than the isoelectric point (pI) of the peptides, while the peptides existed as smaller particles (<2 nm) near their pI values and in the acidic range. They showed poor affinity for calcium and phosphates, comparable to full-length amelogenin and variants. The secondary structure determination showed that the 11-amino-acid peptide contained defined secondary structure comprising beta-sheets and turns. Atomic force microscopy analysis revealed the presence of thin, disk-like nanostructures of 54.4 nm diameter for the 28-amino-acid peptide and 54.9 nm diameter for the 11-amino acid peptide, whereas no definite structures were observed for the 17-amino-acid peptide. It is concluded that the amelogenin C-terminal peptides are capable of interacting with calcium and phosphate ions, of self-assembly into nanostructures, and may have some secondary structure, and hence may have some role in enamel synthesis.

The aim of this study was to test the microtensile bond strength (μTBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm². The μTBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student–Newman–Keuls test (α = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC–dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H₂O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in μTBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine.

Green tea is a popular drink throughout the world, and it contains various components, including the green tea polyphenol (−)-epigallocatechin gallate (EGCG). Tea interacts with saliva upon entering the mouth, so the interaction between saliva and EGCG interested us, especially with respect to EGCG–protein binding. SDS-PAGE revealed that several salivary proteins were precipitated after adding EGCG to saliva. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) peptide mass fingerprinting indicated that the major proteins precipitated by EGCG were alpha-amylase, S100, and cystatins. Surface plasmon resonance revealed that EGCG bound to alpha-amylase at dissociation constant (K_d) = 2.74 × 10⁻⁶ M, suggesting that EGCG interacts with salivary proteins with a relatively strong affinity. In addition, EGCG inhibited the activity of alpha-amylase by non-competitive inhibition, indicating that EGCG is effective at inhibiting the formation of fermentable carbohydrates involved in caries formation. Interestingly, alpha-amylase reduced the antimicrobial activity of EGCG against the periodontal bacterium Aggregatibacter actinomycetemcomitans. Therefore, we considered that EGCG–salivary protein interactions might have both protective and detrimental effects with respect to oral health.

The wingless-type MMTV integration site family (Wnt) signalling pathway plays a crucial role in craniofacial development. Recently, nucleotide variants in WNT genes have been shown to be associated with oral congenital anomalies, including facial clefts. Therefore, in the current study we decided to assay the association of nucleotide variants in selected WNT genes with the risk of non-syndromic cleft lip with or without cleft palate (NCL/P) in the Polish population. Fourteen polymorphisms in WNT3, WNT3A, WNT5A, WNT8A, WNT9B, and WNT11 were tested in a group of 210 patients with NCL/P and in a properly matched control group. The most significant results were found for the WNT3 rs3809857 variant, which, under the assumption of a recessive model, was associated with a two-fold decrease in the risk of NCL/P (OR_{TT vs. GT + GG} = 0.492, 95% CI: 0.276–0.879, P = 0.015). Moreover, haplotype analysis revealed that WNT3 is significantly correlated with NCL/P. The global P-values for haplotypes of rs12452064_rs7207916 and rs3809857_rs12452064_rs7207916 were 0.0034 and 0.0014, respectively, and these results were statistically significant, even after the permutation test correction. In conclusion, our study confirmed the involvement of polymorphisms in the WNT3 gene in NCL/P aetiology in the tested population.

Several single nucleotide polymorphisms in survivin gene promoters, notably -31G/C, have been shown to modulate the expression and activity of the survivin protein. Consequently, the -31G/C polymorphism has been identified as a risk factor for the development of several types of tumors. The aim of this study was to investigate a possible association between the -31G/C polymorphism and the risk for keratocystic odontogenic tumor (KCOT) development. DNA from 52 biopsy specimens of KCOTs and from 82 buccal swabs of healthy individuals was subjected to PCR restriction fragment length polymorphism analysis to identify individual genotypes. The distribution of genotypes in KCOT and control groups, respectively, was: GG: 30 (57.7%) vs. 26 (31.7%); CG: 17 (32.7%) vs. 45 (54.9%); and CC: 5 (9.6%) vs. 11 (13.4%), respectively. These differences were statistically significant. The G allele was more common in the KCOT group than in the control group: 76 (74%) vs. 96 (59%), respectively. Logistic regression analysis showed that GC heterozygotes had a considerably decreased susceptibility for KCOTs compared with GG homozygotes. The same was true for GC+CC vs. GG. The GG genotype of the -31G/C polymorphism might be a risk factor for KCOT development.

Epigenetic modifications of DNA and its associated proteins influence gene expression. The -1087 interleukin-10 (IL10) gene polymorphism is associated with differences in IL10 expression. The objectives of this study were to analyze the effect of DNA methylation and histone modifications on IL10 gene expression, the differences in epigenetic modifications between GG and AA genotypes of the -1087 IL10 gene polymorphism, and the methylation pattern in the region close to the -1087 position. Using B cells obtained from subjects with GG and AA genotypes we demonstrated that treatment with histone deacetylase inhibitors and 5-aza-2-deoxycytidine resulted in an increase in the production of IL10 mRNA. The chromatin immunoprecipitation assay revealed that stimulation with lipopolysaccharide resulted in a higher fold increase in the acetylation of histone H4 and in the methylation of histone H3 for GG genotype cells than for AA genotype cells. The increase in acetylation of histone H3 was larger for AA genotype cells than for GG genotype cells. For unstimulated cells the acetylation and methylation of histone H3 were higher for GG genotype cells than for AA genotype cells, while AA genotype cells had a higher increase in acetylation of histone H4. DNA methylation assays revealed that the three CpG sites distal to the -1087 site were methylated in blood cells and gingival tissues.

In this study we determined whether craniofacial development in rats could be influenced by an early temporary (3 d) nasal obstruction associated with forced oral breathing. The rats were killed at specific time points after surgery. Plasma samples were taken for biochemical analyses, and cephalometric measurements were performed. Shortly after nasal obstruction, the vertical nasomaxillary complex and the longitudinal skull base proved to be smaller in both sexes of test rats compared with controls. This was maintained in male rats but not in female rats. In female rats, only the longitudinal skull base remained somewhat shorter as the animals grew older. Reversible nasal obstruction was further associated with reduced dimensions of the olfactory bulbs lasting into adulthood and an initial decrease in lung weight. One day after implementing nasal obstruction, basal corticosterone levels had increased (by over 1,000%) and stayed at a high level in female rats. In male rats, however, the corticosterone level seemed to return to normal by day 90. Oral breathing was also associated with a lower level of thyroid hormone, especially at the shorter term intervals in both sexes. We conclude that a 3-d nasal obstruction period in young rats leads to long-term hormonal changes and to craniofacial structural adaptation.

Hertwig’s epithelial root sheath (HERS), epithelial rests of Malassez (ERM) cells, and reduced ameloblasts undergo apoptosis during tooth development. This study examined the effects of dental follicle cells and cementoblasts on the apoptosis of ameloblast-lineage and HERS/ERM cells derived from the enamel organ. We also elucidated the induction pathways and identified the apoptotic pathway involved in this process. Here, we showed terminal deoxynucleotidyl transferase-mediated biotin–dUTP nick-end labeling (TUNEL)-positive HERS cells and reduced ameloblasts near dental follicle cells during tooth development. Co-culturing ameloblast-lineage cell line (ALC) ameloblasts and HERS/ERM cells with either dental follicle cells or OCCM-30 cementoblasts markedly enhanced the apoptosis of ameloblasts and HERS/ERM cells compared with cells cultured alone. However, dental follicle cells and cementoblasts did not modulate the apoptotic responses of co-cultured non-odontogenic MCF10A or KB cells. When ameloblasts + HERS and cementoblasts + dental follicle cells were co-cultured, the expression of Fas ligand (FasL) increased in cementoblasts + dental follicle cells, while the expression of Fas increased in ameloblasts + HERS. Interestingly, recombinant FasL induced ameloblast apoptosis while the cementoblast-induced ameloblast apoptosis was suppressed by the Fas/FasL antagonist Kp7-6. These results suggest that during tooth development, dental follicle cells and cementoblasts induce apoptosis of ameloblast-lineage and HERS/ERM cells through the Fas–FasL pathway, but do not induce the apoptosis of non-odontogenic epithelial cells.

The restoration of muscles in the soft palate of patients with cleft lip and/or palate is accompanied by fibrosis, which leads to speech and feeding problems. Treatment strategies that improve muscle regeneration have only been tested in limb muscles. Therefore, in the present study the myogenic potential of muscle progenitor cells (MPCs) isolated from head muscles was compared with that of limb muscles. Muscle progenitor cells were isolated from the head muscles and limb muscles of rats and cultured. The proliferation of MPCs was analysed by DNA quantification. The differentiation capacity was analysed by quantifying the numbers of fused cells, and by measuring the mRNA levels of differentiation markers. Muscle progenitor cells were stained to quantify the expression of paired box protein Pax 7 (Pax-7), myoblast determination protein 1 (MyoD), and myogenin. Proliferation was similar in the head MPCs and the limb MPCs. Differentiating head and limb MPCs showed a comparable number of fused cells and mRNA expression levels of myosin-1 (Myh1), myosin-3 (Myh3), and myosin-4 (Myh4). During proliferation and differentiation, the number of Pax-7⁺, MyoD⁺, and myogenin⁺ cells in head and limb MPCs was equal. It was concluded that head and limb MPCs show similar myogenic capacities in vitro. Therefore, in vivo myogenic differences between those muscles might rely on the local microenvironment. Thus, regenerative strategies for limb muscles might also be used for head muscles.

Relearning of motor skills is important in neurorehabilitation. We investigated the improvement of training success during simple tongue protrusion (two force levels) and a more complex tongue-training paradigm using the Tongue Drive System (TDS). We also compared subject-based reports of fun, pain, fatigue, and motivation between paradigms. Three randomized sessions and one control experiment were performed. Sixteen healthy subjects completed two different 1-h sessions of simple tongue training with 1 N and 3 N, respectively, and one TDS session. After 1 wk, six out of 16 subjects participated as experienced subjects with six naive subjects in a control experiment with 2 × 5-min TDS training separated by a 30-min rest. Performance improved during training in all sessions. The mean ± SEM relative increase in success was 80 ± 12% (1 N), 52 ± 11% (3 N), and 285 ± 45% (TDS). In the control experiment the experienced group performed equal to the last 5 min of their first TDS session and neither group improved during rest. Training with the TDS was rated as more fun, less painful, less fatiguing, and more motivating compared with simple tongue training. In conclusion, force level and complexity of tongue training influences behavioral aspects of tongue motor learning.

The aim of this study was to assess oral health-related behaviours among dentate adults. As part of the comprehensive Finnish Health 2000 Survey, this study included dentate subjects, 30–64 yr of age (n = 4,417). Based on interview and questionnaire data, information on nine oral health-related habits was elicited. On average, study subjects reported 4.4 (SD = 1.5) oral health-promoting behaviours among the nine behaviours investigated, the mean number differing according to subjects’ gender, educational level, marital status, and employment status. Older age, higher level of education, cohabiting, and being employed were indications of higher numbers of oral health-promoting habits than were younger age, lower levels of education, being single, or being unemployed. Oral health-promotion activities should be tailored and targeted in terms of adults’ socio-economic and demographic characteristics, and directed especially towards men, those with lower education, and those who are single or unemployed.

The aim was to compare the oral health status of patients with eating disorders (EDs), with sex- and age-matched controls, with a view to identify self-reported and clinical parameters that might alert the dental healthcare professional to the possibility of EDs. All patients who entered outpatient treatment in an ED clinic during a 12-month period were invited to participate. Of 65 ED patients who started psychiatric/medical treatment, 54 agreed to participate. Eating disorder patients and controls answered a questionnaire and underwent dental clinical examinations. Multivariate analysis identified significantly higher ORs for ED patients to present dental problems (OR = 4.1), burning tongue (OR = 14.2), dry/cracked lips (OR = 9.6), dental erosion (OR = 8.5), and less gingival bleeding (OR = 1.1) compared with healthy controls. Sensitivity and specificity for the correct classification of ED patients and controls using the five variables was 83% and 79%, respectively. The ED patients with vomiting/binge eating behaviors reported worse perceived oral health (OR = 6.0) and had more dental erosion (OR = 5.5) than those without such behavior. In ED patients with longer duration of the disease, dental erosion was significantly more common. In conclusion, oral health problems frequently affect ED patients, and this needs to be considered in patient assessment and treatment decisions.

Little is known about the well-being of oral and maxillofacial surgeons. The aim of this study was to measure the levels of burnout risk and the demanding work aspects of Dutch oral and maxillofacial surgeons, as well as the levels of positive work engagement and stimulating aspects of the work environment. The Maslach Burnout Inventory, Dutch version (UBOS), and inventories on positive engagement, work demands, and stimulating aspects of work, were sent to all 179 Dutch oral and maxillofacial surgeons currently in clinical practices. With a 70% response, UBOS mean scores on Emotional Exhaustion and Depersonalization appeared lower, and on Personal Accomplishment appeared higher, when compared with relevant reference scores. Engagement scores appeared to be relatively high. Mean scores on the work demands subscales were all well below the scale midpoint, whereas work resources were all well above. Dutch oral and maxillofacial surgeons showed relatively favorable burnout and engagement levels. The aspects of the work environment that best explain differences in burnout are ‘Practice demands and organization’ and ‘Lack of variation and perspective in work’. Differences in engagement are best explained by ‘Variety in work’ and ‘Positive effect upon patients’. It is remarkable that all work demands show relatively low levels and all stimulating work aspects show relatively high levels.

Cognitive elements play a key role in dental anxiety. Nevertheless, relatively little is known about how dental treatments and frequency of visits to the dentist are related to dental fear and its cognitive antecedents. This study aimed to explore the relationships between dental visits, past treatment experiences, expectations on the aversiveness/probability of negative dental events, and dental fear in children. The participants were 147 children (60% female; mean age = 12.0 yr) who completed a questionnaire comprising measures of dental treatment-related experience (attendance, fillings, and extractions), perceived aversiveness and probability of dental events, and dental anxiety. Bivariate correlations and multiple linear regression analyses were used to analyze the data. A higher frequency of dental visits was associated with less dental fear and a decreased belief in the probability of negative events occurring during treatment. The type of treatments received was not directly linked to dental fear. However, having received fillings was significantly associated with the perceived probability of negative dental events, whereas extractions were positively associated with these expectations but negatively associated with the perceived aversiveness of possible dental events. Regular dental visits, as well as dental treatments, can influence, in different ways, cognitive elements associated with dental anxiety in children.

Although previous research has successfully tested the usefulness of cognitive and non-cognitive factors to predict dental anxiety, they have rarely been jointly analysed. This study therefore aimed to compare the relative predictive power of a set of cognitive and non-cognitive factors in accounting for dental anxiety scores. A sample of 167 Spanish undergraduate students (81.4% women; mean age 21.2 yr) completed a questionnaire comprising measures of dental anxiety, non-cognitive antecedents of dental anxiety (i.e. past aversive dental experiences, exposure to dentally fearful relatives, and trait-based negative mood), and cognitive variables (i.e. dental-related cognitive vulnerability, probability/aversiveness expectancies, and dental cognitions and beliefs). In multiple linear regression analyses, cognitions were found to significantly increase the proportion of variance accounted for in dental fear scores (ΔR² = 0.15, maximum ΔR² = 0.35). Cognitive factors were found to be the best individual predictors of dental fear (β-values ranging from 0.23–0.66). Furthermore, scores for past aversive treatment experiences and negative mood were not significant predictors of scores for dental anxiety when cognitive variables were included in the models. The analysis of cognitive mechanisms involved in dental anxiety is revealed as a potentially important point in better understanding this problem.

Resin-based dental restorative materials contain allergenic methacrylate monomers, which may be released into saliva after restorative treatment. Monomers from resin-based composite materials have been demonstrated in saliva in vitro; however, studies analyzing saliva after restorative therapy are scarce. The aim of this study was to quantify methacrylate monomers in saliva after treatment with a resin-based composite filling material. Saliva was collected from 10 patients at four start points – before treatment, and 10 min, 24 h, and 7 d after treatment – and analysed by combined chromatography/mass spectrometry. The monomers bisphenol-A diglycidyl methacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), and urethane dimethacrylate (UDMA) were detected and quantified in the samples collected shortly (10 min) after treatment. The amounts detected ranged from 0.028 to 9.65 μg ml⁻¹ for Bis-GMA, from 0.015 to 0.19 μg ml⁻¹ for HEMA, and from 0.004 to 1.2 μg ml⁻¹ for UDMA. Triethyleneglycol dimethacrylate (TEGDMA) was detected in four of the samples. Ethoxylated bisphenol-A dimethacrylate (Bis-EMA) was not detected. Monomers were not detected in saliva samples collected before treatment, or 24 h or 7 d after treatment, with the exception of one sample, 24 h after treatment, in which HEMA was detected. In conclusion, monomers from the investigated resin-based composite and adhesive system were present in saliva shortly after treatment. One week after treatment, no monomers could be detected in patients’ saliva samples.