In vivo imaging in the oral cavity by endoscopic optical coherence tomography

The common way to diagnose hard and soft tissue irregularities in the oral cavity is initially the visual inspection by an experienced dentist followed by further medical examinations, such as radiological imaging and/or histopathological investigation. For the diagnosis of oral hard and soft tissues, the detection of early transformations is mostly hampered by poor visual access, low specificity of the diagnosis techniques, and/or limited feasibility of frequent screenings. Therefore, optical noninvasive diagnosis of oral tissue is promising to improve the accuracy of oral screening. Considering this demand, a rigid handheld endoscopic scanner was developed for optical coherence tomography (OCT). The novelty is the usage of a commercially near-infrared endoscope with fitting optics in combination with an established spectral-domain OCT system of our workgroup. By reaching a high spatial resolution, in vivo images of anterior and especially posterior dental and mucosal tissues were obtained from the oral cavity of two volunteers. The convincing image quality of the endoscopic OCT device is particularly obvious for the imaging of different regions of the human soft palate with highly scattering fibrous layer and capillary network within the lamina propria.

Identification of New Compounds from Sage Flowers (Salvia officinalis L.) as Markers for Quality Control and the Influence of the Manufacturing Technology on the Chemical Composition and Antibacterial Activity of Sage Flower Extracts

Parts of Salvia species such as its flowers and leaves are currently used as a culinary herb and for some medicinal applications. To distinguish the different sage extracts it is necessary to analyze their individual chemical compositions. Their characteristic compounds might be established as markers to differentiate between sage flowers and leaf extracts or to determine the manufacturing technology and storage conditions. Tri-p-coumaroylspermidine can be detected only in flowers and has been described here for Salvia and Lavandula species for the first time. Markers for oxidation processes are the novel compounds salviquinone A and B, which were generated from carnosol by exposure to oxygen. Caffeic acid ethyl ester was established as an indirect marker for the usage of ethanol as extraction solvent. The compounds were identified by LC-QTOF-HRESIMS, LC-MS, NMR, IR, and single-crystal X-ray diffraction after isolation by semipreparative HPLC. Furthermore, sage flower resin showed interesting antibacterial in vitro activities against Gram-positive and Gram-negative bacteria.

Detection of carious lesions utilizing depolarization imaging by polarization sensitive optical coherence tomography

As dental caries is one of the most common diseases, the early and noninvasive detection of carious lesions plays an important role in public health care. Optical coherence tomography (OCT) with its ability of depth-resolved, high-resolution, noninvasive, fast imaging has been previously recognized as a promising tool in dentistry. Additionally, polarization sensitive imaging provides quantitative measures on the birefringent tissue properties and can be utilized for imaging dental tissue, especially enamel and dentin. By imaging three exemplary tooth samples ex vivo with proximal white spot, brown spot, and cavity, we show that the combination of polarization sensitive OCT and the degree of polarization uniformity (DOPU) algorithm is a promising approach for the detection of proximal carious lesions due to the depolarization contrast of demineralized tissue. Furthermore, we investigate different sizes of the DOPU evaluation kernel on the resulting contrast and conclude a suitable value for this application. We propose that DOPU provides an easy to interpret image representation and appropriate contrast for possible future screening applications in early caries diagnostics.

Odontoblast-like differentiation and mineral formation of pulpsphere derived cells on human root canal dentin in vitro

BACKGROUND

The revitalization or regeneration of the dental pulp is a preferable goal in current endodontic research. In this study, human dental pulp cell (DPC) spheres were applied to human root canal samples to evaluate their potential adoption for physiological tissue-like regeneration of the dental root canal by odontoblastic differentiation as well as cell-induced mineral formation.

METHODS

DPC were cultivated into three-dimensional cell spheres and seeded on human root canal specimens. The evaluation of sphere formation, tissue-like behavior and differentiation as well as mineral formation of the cells was carried out with the aid of optical light microscopy, immunohistochemical staining and scanning electron microscopy (SEM).

RESULTS

Spheres and cells migrated out of the spheres showed an intense cell-cell- and cell-dentin-contact with the formation of extra cellular matrix. In addition, the ingrowth of cell processes into dentinal tubules and the interaction of cell processes with the tubule walls were detected by SEM-imaging. Immunohistochemical staining of the odontoblast specific matrix proteins, dentin matrix protein-1, and dentin sialoprotein revealed an odontoblast-like cell differentiation in contact with the dentin surface. This differentiation was confirmed by SEM-imaging of cells with an odontoblast specific phenotype and cell induced mineral formation.

CONCLUSIONS

The results of the present study reveal the high potential of pulp cells organized in spheres for dental tissue engineering. The odontoblast-like differentiation and the cell induced mineral formation display the possibility of a complete or partial "dentinal filling" of the root canal and the opportunity to combine this method with other current strategies.

In vivo imaging of human oral hard and soft tissues by polarization-sensitive optical coherence tomography

Since optical coherence tomography (OCT) provides three-dimensional high-resolution images of biological tissue, the benefit of polarization contrast in the field of dentistry is highlighted in this study. Polarization-sensitive OCT (PS OCT) with phase-sensitive recording is used for imaging dental and mucosal tissues in the human oral cavity in vivo. An enhanced polarization contrast of oral structures is reached by analyzing the signals of the co- and crosspolarized channels of the swept source PS OCT system quantitatively with respect to reflectivity, retardation, optic axis orientation, and depolarization. The calculation of these polarization parameters enables a high tissue-specific contrast imaging for the detailed physical interpretation of human oral hard and soft tissues. For the proof-of-principle, imaging of composite restorations and mineralization defects at premolars as well as gingival, lingual, and labial oral mucosa was performed in vivo within the anterior oral cavity. The achieved contrast-enhanced results of the investigated human oral tissues by means of polarization-sensitive imaging are evaluated by the comparison with conventional intensity-based OCT.

Impact of customary fluoride rinsing solutions on the pellicle's protective properties and bioadhesion in situ

This study investigated the impact of customary fluoride based mouthrinses on the ultrastructure and the functional properties of the in situ pellicle, considering the prevention of erosion (8 volunteers) and initial biofilm formation (12 volunteers). Bovine enamel slabs were carried intraorally. After 1 min of pellicle formation, the subjects rinsed with elmex Kariesschutz (A), Dontodent Med Care (B), meridol (C) or elmex Zahnschmelzschutz Professional (D) for 1 min. In situ pellicle formation was continued up to 30 min/8 h before processing the slabs in vitro. Erosion was simulated by incubating the specimens in HCl (pH 3.0, 2.3, 2.0) for 120 s, measuring the kinetics of calcium/phosphate release photometrically; representative samples were evaluated by TEM and EDX. Bacterial adhesion was visualized fluorescence microscopically (DAPI/BacLight). Native enamel slabs or physiological pellicle samples served as controls. All investigated mouthrinses enhanced the erosion preventive pellicle effect in dependence of the pH-value. A significant decrease of Ca/P release at all pH values was achieved after rinsing with D; TEM/EDX confirmed ultrastructural pellicle modifications. All mouthrinses tendentially reduced bacterial adherence, however not significantly. The mouthrinse containing NaF/AmF/SnCl₂ (D) offers an effective oral hygiene supplement to prevent caries and erosion.

Effect of Sonic Application of Self-etch Adhesives on Bonding Fiber Posts to Root Canal Dentin

PURPOSE

To evaluate the effect of sonic application of 5 different self-etch adhesives on the push-out bond strength of fiber posts in root canals.

MATERIALS AND METHODS

In a preliminary test, 24 teeth were treated with manual and sonically assisted bonding, then a composite cylinder was built up to test the shear bond strength as a proof of principle. In the main test, 120 root canals were endodontically prepared and divided into 10 groups: 5 self-etch adhesives (Futurabond DC, Futurabond M, Futurabond U, Optibond XTR, Universalbond), each applied under manual and sonic application modes. After insertion of the fiber posts using the specific adhesive and a dual-curing composite, the teeth were sectioned and the push-out test was performed. The specimens were analyzed by light and scanning electron microscopy. Statistical analysis was performed using the Shapiro-Wilk test, one-way ANOVA and the Tamhane test.

RESULTS

Sonic application of self-etch adhesive systems did not increase the bond strength of fiber posts in root canals. In general, the bond strength decreased from the coronal to the apical part of the root canal, irrespective of the applied method. The best post retention was achieved with Futurabond U and Optibond XTR.

CONCLUSION

Sonic application of self-etch adhesives did not improve the fiber post retention in the root canal and can therefore not be recommended. Nevertheless, sonic application of etch-and-rinse adhesives can increase the bond strength to coronal dentin.

Is it really penetration? Locomotion of devitalized Enterococcus faecalis cells within dentinal tubules of bovine teeth

OBJECTIVE

The aim of the present study was to evaluate the penetration characteristics of devitalized and vital E. faecalis cells into root dentinal tubules.

DESIGN

Thirteen root canals were incubated with devitalized (4days, 7days, 14days, 28days) and vital (28days) E. faecalis strains (streptomycin-resistant strains) after root canal enlargement (size 80, taper 0.02) with 3 % NaOCl solution. The smear layer was intentionally removed with 20 % EDTA before inoculation. Samples were processed for analysis by scanning electron microscopy (SEM) and DAPI (4',6-diamidino-2-phenylindole) staining. DAPI was conducted for fluorescence microscopic visualization of the bacterial penetration into dentinal tubules. The penetration depth was calculated with the measurement tool of the Axio Vision program (Zeiss, Jena, Germany).

RESULTS

Devitalized E. faecalis strains were able to penetrate into dentinal tubules of the root canal. Apikal penetration depths of the devitalized cells were 100.67μm±26.54μm after 7days, 230.67μm±111.5μm after 14days and 266.5μm±92.63μm after 28days of incubation. The total number and penetration depth of E. faecalis cells was lower compared to a vital suspension of E. faecalis (1002.45μm) after 28days. It was noted that bacterial penetration was not common to all of the dentinal tubules in the vital E. faecalis control and especially in the devitalized control.

CONCLUSIONS

Increased exposure times of devitalized bacteria into root canals lead to an increased number of penetrated dentinal tubules as well as to a deeper penetration.

Initial microbial colonization of enamel in children with different levels of caries activity: An in situ study

PURPOSE

To investigate patterns of overnight in situ microbial colonization of enamel in children.

METHODS

Overall, 29 children (aged 5-9 years) participated in the study. Nine were caries-free with no decayed, missing, or filled teeth (DMFT), 11 were caries-rehabilitated (DMFT ≥ 2, no active carious lesions), and nine were caries-active (DMFT ≥ 2, at least two carious lesions). Bovine enamel samples were fixed on individual upper jaw splints stored overnight in situ. 4',6-diamidino-2-phenylindole (DAPI) combined with Concanavalin A staining was applied for fluorescence microscopic visualization of total adherent bacteria and glucans. Fluorescence in situ hybridization (FISH) was used for distinction of eubacteria, streptococci, and Candida albicans. Salivary samples were investigated for Streptococcus mutans (S. mutans) by using CRT bacteria test and yeasts with Calcofluor white (CFW) staining.

RESULTS

With all fluorescence methods, bacteria but not Candida albicans were detected on enamel samples. No statistically significant differences were observed in distribution patterns of the adherent bacteria between the groups. CFW staining indicated fungal structures in saliva samples of all participants. Based on CRT test results, the lowest amount of S. mutans were observed in caries-free children. Thus, initial microbial colonization patterns of enamel in children are not influenced by caries activity.

CLINICAL SIGNIFICANCE

Caries activity in children may influence the process of initial bioadhesion and thus distribution patterns of bacterial attachment to the enamel surface. Investigation of in situ biofilm formation might provide valuable insights regarding the varying caries susceptibility in children.

The Bleeding on Brushing Index: a novel index in preventive dentistry

BACKGROUND

The aim of this study was to evaluate the suitability of a dichotomous index, based on a special interdental brushing tool, to detect initial pathological processes in interproximal areas. Furthermore, different techniques of interdental hygiene were compared.

METHODS

Participants (n = 108) were instructed to clean their teeth using the Bass technique and were randomly assigned to three groups according to the type of interdental cleaning used: group A, use of interdental brushes; group B, no interdental hygiene (the control group); and group C, use of dental floss. Approximal Plaque Index (API), Plaque Index (PI), modified Sulcus Bleeding Index (mSBI) and the Bleeding on Brushing Index (BOB) were measured at baseline, and after 2 (t1) and 4 (t2) weeks. Statistical analysis was performed using the Wilcoxon test and the Mann-Whitney U-test.

RESULTS

One-hundred and six participants completed the study. The BOB decreased significantly in all groups (P < 0.001) with the most pronounced reduction being recorded for group A (baseline: 49.3 ± 23.0%; 4 weeks: 5.1 ± 6.9%). Also, the mSBI (P < 0.001) decreased significantly in all groups during the study. The API appeared to be less affected by the oral hygiene than other indices. The highest correlation was observed between BOB and mSBI (r = 0.785, P < 0.001).

CONCLUSION

The BOB is a valuable complement for the existing array of indices in preventive dentistry, and is able to detect potential pathological processes in interproximal spaces. Additionally, this study suggests that interdental hygiene with individually selected brushes is superior to flossing.

CLINICAL RELEVANCE

With the BOB, gingival inflammation can be demonstrated to patients, which could increase compliance.

Enzymology and Ultrastructure of the in situ Pellicle in Caries-Active and Caries-Inactive Patients

Aim: The present study aimed to evaluate the impact of caries activity on the key enzymes and the ultrastructure of the in situ pellicle. Methods: Pellicle formation was performed on bovine enamel slabs. Intraoral exposure (3, 30, and 120 min) was accomplished by 14 caries-active (DMFS: 22.7 ± 12.1) and 13 caries-inactive (DMFS: 1.5 ± 1.8) individuals. The enzyme activities (lysozyme, peroxidase, α-amylase, glycosyltransferase [GTF]) in the in situ pellicle and resting saliva of all participants were analyzed directly after oral exposure. In addition, a simultaneous visualization of these enzymes, extracellular glucans, and adherent bacteria was carried out. Fluorescent patterns were analyzed with fluorescence labeling and 4′,6-diamidino-2-phenylindole/concanavalin A staining. In addition, the distribution of GTF B, C, and D and the ultrastructure of the pellicle were examined by gold immunolabeling and transmission electron microscopy with selected samples. Results: Enzyme activities of amylase, peroxidase, lysozyme, and GTF were detected on all enamel slabs in an active conformation. Neither exposure time nor caries activity had an impact on the enzyme activities. Gold immunolabeling indicated that the pellicle of caries-active subjects tends to more GTF D molecules. The pellicles of caries-inactive and -active individuals revealed a similar ultrastructural pattern. Conclusion: The enzyme activities as well as the pellicle's ultrastructure are of high similarity in caries-active and -inactive subjects. Thereby, oral exposure time has no significant influence. This reflects a high uniformity during the initial phase of bioadhesion (3-120 min) concerning enzymatic functions. However, there is a tendency towards more GTF D in caries-active individuals.

Comparison of two cone-beam computed tomography systems in the visualization of endodontic structures

An important part of endodontic diagnosis and treatment is the adequate visualization of root canal anatomy. The objective of the present study was to compare two different three-dimensional cone-beam computed tomography (CBCT) systems, Scanora 3D and 3D Accuitomo 170, with respect to their visualization of endodontic canal systems and potential pathological alterations. Seventy extracted human teeth were investigated with regard to the radiographic detection of number of root canals, lateral canals, root canal fillings and posts, vertical root fractures, and the occurrence of image artifacts. For each evaluation parameter under investigation the radiographic diagnoses obtained by the two different CBCT systems under investigation were similarly accurate, without statistically significant differences. The evaluation of teeth containing highdensity foreign materials was impaired for both CBCT systems because of image artifacts. However, a difference between the CBCT systems was not observed. In conclusion, both CBCT systems were found to be similarly suitable for the visualization of endodontic structures in vitro.

Effect of Tannic Acid on the Protective Properties of the in situ Formed Pellicle

OBJECTIVES

In the present in situ/ex vivo study the impact of tannic acid on the erosion-protective properties of the enamel pellicle was tested. Additionally, the antiadherent and antibacterial effects of tannic acid were evaluated.

METHODS

The pellicle was formed in situ on bovine enamel samples fixed on individual splints worn by 6 subjects. Following 1 min of pellicle formation the volunteers rinsed for 10 min with tannic acid. After further oral exposure for 19 min, 109 min, and 8 h overnight, respectively, slabs were incubated in HCl ex vivo (pH 2.0, 2.3, 3.0) over 120 s. Subsequently, kinetics of calcium and phosphate release were measured photometrically. Samples after a 1-min fluoride mouth rinse as well as enamel samples with and without a 30-min in situ pellicle served as controls. Antiadherent effects were evaluated after a 1-min rinse with tannic acid and oral exposure of the slabs overnight. DAPI (4',6-diamidino-2-phenylindole) combined with concanavalin A staining and live/dead staining was used for fluorescence microscopic visualization and quantification of adherent bacteria and glucans. Modification of the pellicle's ultrastructure by tannic acid was evaluated by transmission electron microscopy (TEM).

RESULTS

Tannic acid significantly improved the erosion-protective properties of the pellicle in a pH-dependent manner. Bacterial adherence and glucan formation on enamel were significantly reduced after rinses with tannic acid as investigated by fluorescence microscopy. TEM imaging indicated that rinsing with tannic acid yielded a sustainable modification of the pellicle; it was distinctly more electron dense.

CONCLUSION

Tannic acid offers an effective and sustainable approach for the prevention of caries and erosion.

Decision criteria for replacement of fillings: a retrospective study

The exchange of restorations goes along with the loss of healthy tooth structure. Therefore, it is important to investigate helpful decision criteria for the replacement of fillings. Five hundred forty-four filling replacements were evaluated retrospectively. Thereby, different clinical parameters were correlated with the clinical finding of caries directly after removal of the existing filling. The parameters checked for correlations were amalgam and composite, age, and size of the filling, morphology, condition of the filling, type of caries, oral hygiene, anamnesis of the respective tooth, and the decisive factor to replace the restoration. Statistical evaluation was performed by chi-squared-test (P < 0,05) and by regression analysis (Power: 80%). A percentage of 69.8% of all cavities showed softened dentin if exploring with the probe after the removal of the restoration, 7.6% were stainable with caries detector, and 22.6% of the cavities were caries free. Significant indicators for a carious lesion were high age of restoration, imperfections at the margin of the filling, a positive pain sensation in correlation with composite fillings, and multi-surface amalgam fillings. On suspicion of caries, the following decision criteria should encourage the dentist to remove a filling: High age of the filling, imperfections at the margin of the filling, especially fillings with marginal cracks, visible secondary caries, a positive pain sensation in composite filled teeth, and multi-surface amalgam fillings. Filling removals only performed due to the patient's desire for removal should be critically regarded, as most of these fillings are caries free.

Oral Health and Quality of Life in Old Age: A Cross-Sectional Pilot Project in Germany and Poland

BACKGROUND

The process of ageing influences all dimensions of social life and personal well-being, but the influence of health on different dimensions of quality of life (QoL) among the elderly is rarely examined.

OBJECTIVES

The aim of the pilot study is to test the feasibility of a comprehensive study design to evaluate general and dental health as well as QoL in a bi-national sample. In addition, this pilot study should allow for the exploration of potential interactions between QoL, socioeconomic, health and oral health variables.

MATERIAL AND METHODS

Individuals aged 64 years and older (n = 100) from university dental clinics of the Wroclaw Medical University, Poland (n = 50) and of the University Hospital in Dresden, Germany (n = 50) were examined. The oral health status of participants was assessed by clinical examination. Socio-demographic, environmental and general health status were evaluated during the medical interview. General quality of life (GQoL) was assessed by an overall question with a visual analogue scale (VAS) from -5 (worst) to +5 (best). Health-related quality of life (HRQoL) and oral health-related quality of life (OHRQoL) were measured with the EQ-5D and OHIP-14 questionnaires. Statistical analyses comprised Pearson's c2 test, Wilcoxon test, linear regression model for statistical analysis and different multivariate linear regression analyses.

RESULTS

For the GQoL-VAS-Score the results for QoL measurements were 1.22 ± 2.62 (x± SD), for EQ-5D-Score 7.45 ± 2.25 (x± SD), and for OHIP-14-ADD-Score 11.04 ± 13.56 (x± SD). Differences between Polish and German populations were observed.

CONCLUSIONS

The study design proved to be feasible for a senior population. The overall GQoL question, EQ-5D and OHIP-14 were regarded as appropriate instruments. Subjective and objective (oral) health measures showed differences between Germany and Poland. For methodological reasons, these differences are not generalizable, but of value for study hypotheses in larger samples.

Does diet influence salivary enzyme activities in elephant species?

Asian elephants (Elephas maximus) and African elephants (Loxodonta africana) are herbivore generalists; however, Asian elephants might ingest a higher proportion of grasses than Africans. Although some studies have investigated nutrition-specific morphological adaptations of the two species, broader studies on salivary enzymes in both elephant species are lacking. This study focuses on the comparison of salivary enzymes activity profiles in the two elephant species; these enzymes are relevant for protective and digestive functions in humans. We aimed to determine whether salivary amylase (sAA), lysozyme (sLYS), and peroxidase (sPOD) activities have changed in a species-specific pattern during evolutionary separation of the elephant genera. Saliva samples of 14 Asian and eight African elephants were collected in three German zoos. Results show that sAA and sLYS are salivary components of both elephant species in an active conformation. In contrast, little to no sPOD activity was determined in any elephant sample. Furthermore, sAA activity was significantly higher in Asian compared with African elephants. sLYS and sPOD showed no species-specific differences. The time of food provision until sample collection affected only sAA activity. In summary, the results suggest several possible factors modulating the activity of the mammal-typical enzymes, such as sAA, sLYS, and sPOD, e.g., nutrition and sampling procedure, which have to be considered when analyzing differences in saliva composition of animal species.

The Polyphenolic Composition of Cistus incanus Herbal Tea and Its Antibacterial and Anti-adherent Activity against Streptococcus mutans

The Mediterranean plant Cistus incanus is rich in polyphenols and has shown several pharmacological activities, mainly antibacterial effects. Furthermore, in situ studies revealed that a C. incanus infusion reduces the initial bacterial adhesion in the oral cavity due to the polyphenols, an indication that C. incanus might reduce the risk of caries disease. In the present study, the polyphenols from four different commercial C. incanus herbal teas were extracted by standardized accelerated solvent extraction for in vitro tests and by an infusion for in situ tests. Both extracts were characterized qualitatively and quantitatively by high-performance liquid chromatography and only the polyphenol content differed slightly. By means of diode array detection and mass spectrometry, 29 polyphenols, including ellagitannins, flavanols, and glycosylated flavonols, were identified. Thereby, only quantitative but no qualitative differences between the four samples were detected. Furthermore, the in vitro antibacterial activity of the C. incanus accelerated solvent extracts against Streptococcus mutans, one of the primary cariogenic bacterial species, was examined using a live/dead assay (BacLight®). With this approach, C. incanus yielded antibacterial properties. Additional in situ experiments indicated that rinses with a C. incanus infusion reduced the initial bacterial colonization of enamel samples exposed to oral fluids for over eight hours. Furthermore, it was shown by transmission electron microscopy that the application of a C. incanus infusion modifies the ultrastructure of the acquired enamel pellicle, yielding a more electron-dense morphology. It can be assumed that the polyphenols are responsible for the observed effects.

Application of Plant Extracts for the Prevention of Dental Erosion: An in situ/in vitro Study

OBJECTIVES

Antiadherent and antibacterial effects of certain plant extracts have been proven to be beneficial in preventive dentistry. In the present in situ/in vitro crossover study, the impact of plant extracts rich in polyphenols on the erosion-protective properties of the in situ pellicle was evaluated.

METHODS

Individual splints were prepared for 12 subjects for intraoral exposure of bovine enamel specimens. Following formation of a 1-min pellicle, watery plant extracts (leaves of the wild form of Ribes nigrum, the wild form of Origanum as well as a combination of both) were administered for 10 min in situ. Alternatively, a mouth rinse with fluorides (Elmex Kariesschutz) was performed for 1 min. After further oral exposure for 19/28 min, respectively, slabs were removed and incubated with HCl in vitro over 120 s (pH 2, 2.3, 3). The resulting calcium and phosphate release was quantified photometrically. Slabs with and without a 30-min in situ pellicle served as controls. The modification of pellicle ultrastructure was evaluated by transmission electron microscopy (TEM).

RESULTS

Plant extracts modulated the erosion-protective properties of the native in situ pellicle in all test groups in a pH-dependent manner. The combination of R. nigrum leaves and Origanum enhanced the protective properties of the pellicle at all pH values; the administration of this preparation was comparable, yet superior, to the effect of the fluoridated mouth rinse. TEM images indicated that rinsing with R. nigrum leaves/Origanum yielded a distinctly thicker and more electron-dense pellicle.

CONCLUSION

The combination of certain plant extracts offers a novel approach to the complementary prevention of dental erosion.

Migrants' and professionals' views on culturally sensitive pre-hospital emergency care

This study was designed to explore the views of migrants and professionals on culturally sensitive pre-hospital emergency care in order to adapt such care to migrants' needs. Interviews were conducted with 41 migrants who had received direct (as a patient) or indirect (as a significant other) pre-hospital emergency care. Furthermore, 20 professionals in the field of pre-hospital emergency care were interviewed. The content analysis showed five distinguishable categories based on the statements by the migrants and six categories based on the statements by the professionals. While migrants gave priority to basic proficiencies of first responders such as 'social/emotional competencies' and 'communication skills', the professionals considered '(basic) cultural knowledge', 'awareness' and 'attitude' the most important. Furthermore, migrants provided practical indications, e.g. regarding areas of cultural knowledge, whereas professionals seemed to view the issue of culturally pre-hospital emergency care from a more theoretical perspective. The issues of the culturally sensitive pre-hospital emergency care itself, as well as the varying points of view of the two groups interviewed, resulted in eight recommendations for culturally sensitive pre-hospital emergency care.

Salivary amylase - The enzyme of unspecialized euryphagous animals

INTRODUCTION

Alpha-amylase (EC 3.2.1.1) is the most abundant enzyme in the saliva of man and of several vertebrates. In humans, salivary amylase is mainly formed in the parotid gland; its activity is of high inter-individual and intra-individual variability. The physiological functions of α-amylase have not yet been explored completely. It is well known that the enzyme cleaves the α-(1,4)-glycosidic bonds of polysaccharides. Furthermore it plays an important role in initial bioadhesion in man, facilitating carbohydrate metabolism and bacterial adherence at the tooth surface and therewith caries initiation. Nevertheless, it is still a matter of interest why humans have such high amounts of salivary amylase.

OBJECTIVE

The review presents an evolutionary approach by considering salivary amylase in the animal kingdom with special focus on mammalians divided into the three main nutritional types carnivores, herbivores, and omnivores; it was postulated that for most mammalian animals salivary α-amylase is essential.

RESULTS

The enzyme has been detected in saliva of some herbivores and many omnivorous animals, but not in pure carnivores. Focusing on ruminants, negligible levels or an absence of α-amylase was determined. Presence and activity probably differ depending on the species-specific diet. Animals feeding on unripe fruits, seeds, roots and bulbs exhibit higher activity of salivary α-amylase than species consuming ripe fruits, insects, and vertebrates.

CONCLUSION

In contrast to carnivores and most herbivores, omnivores have considerable amounts of amylase in their saliva. Though, the starch-digesting enzyme has been investigated well, the physiological function of amylase in saliva has not yet been explored completely. It can be hypothesized that nutritional habits affect expression of enzymes in the saliva of animals. It has to be verified, whether α-amylase is genetically or epigenetically determined. As a consequence of the development of agriculture, and following dietary changes, amylase can be recognized as a nutritional and evolutionary marker. Interdisciplinary evolutionary research might offer new perspectives for preventive dentistry.

Possibilities and limits of imaging endodontic structures with CBCT

An adequate portrayal of the root canal anatomy by diagnostic imaging is a prerequisite for a successful diagnosis and therapy in endodontics. The introduction of dental cone beam computed tomography (CBCT) has considerably expanded the scope of imaging diagnostics. The aim of the following study was to evaluate the imaging of endodontic structures with CBCT. One hundred and twenty teeth were examined with a CBCT device (ProMax 3D). Subsequently, the findings of the three-dimensional images were evaluated and compared to those of dental radiographs and tangential section preparations of the examined teeth. Results with high prevalence, such as existing roots and root canals, as well as results with low prevalence, e.g., extremely fine anatomical structures of the endodontic tissue, could be visualized precisely by dental CBCT; side canals, ramifications, communications, pulp stones, and obliterations could also be detected. Additionally, the length of curved root canals could be determined accurately. Likewise, root fractures were visualized reliably with CBCT. However, carious lesions could not be diagnosed adequately, and the evaluation of fillings and prosthetic restorations was complicated due to scattered X-ray artifacts. CBCT datasets qualify to visualize and diagnose small anatomical structures of the endodontic tissue.

Does human saliva decrease the antimicrobial activity of chlorhexidine against oral bacteria?

Background

Several studies have shown the antibacterial effectiveness of 0.2% chlorhexidine (CHX) in both in vitro and in vivo studies. In this way, CHX comes directly in contact with saliva. This in vitro study aimed at investigating the possible neutralizing effect of saliva on CHX.

Methods

Saliva samples (12 ml) were collected from twenty healthy volunteers. The aerobic and anaerobic bacterial counts in saliva were determined on Colombia blood agar (CBA) and yeast cysteine agar (HCB), respectively. Saliva from each subject was divided among 4 experimental groups (3 ml/group). Samples were centrifuged at 4000 g for 10 min. The centrifuged salivary bacteria were incubated with the following solutions: 0.2% CHX in saliva, CHX in saliva with 7% ethanol, CHX in 0.9% NaCl, CHX in 0.9% NaCl with 7% ethanol. After exposure for 1 min or 3 min to these CHX solutions, the CHX was neutralized and the bacteria were cultivated, after which the number of colony forming units (aerobic and anaerobic) was determined.

Results

CHX reduced the CFU in all groups significantly (p = 0.0001). Therefore, CHX had a similar effect on both aerobic and anaerobic microorganisms. Significantly more bacteria survived the effect of CHX when kept in salivary solution. This effect from saliva could be compensated by the addition of ethanol. In the absence of saliva there was no significant difference observed in the effectiveness of CHX with respect to ethanol. Prolonging the exposure time to 3 min enhanced the effectiveness of CHX.

Conclusions

The effect of saliva on the antimicrobial activity of CHX was weak albeit statistically significant. However, addition of 7% ethanol compensates this effect. The impact of saliva on the reduction of the antimicrobial efficacy of mouthrinses such as CHX needs to be taken into consideration with regard to improving their antibacterial properties.

[The concept of culture from the perspective of emergency victims with migration background and experts in the context of emergency care]

OBJECTIVES

In the field of emergency care there is a lack of conceptual foundations of Intercultural Competence. This study aims to elaborate a practice relevant definition of the term culture in order to develop a qualification training.

METHOD

Interviews were conducted with 43 emergency victims and 20 experts. The analysis was performed based on the statements concerning the individual interpretation of the term culture according to the principles of the qualitative content analysis.

RESULTS

The content analysis showed 11 distinguishable categories. Socialisation was a factor frequently mentioned by all persons interviewed. Moreover, emergency victims often linked culture to the fields of behaviour and way of life whilst experts gave priority to functional aspects of culture.

CONCLUSION

A single definition would not be suitable for a common understanding. Rather, several key aspects commonly associated with the term culture should be considered by taking into account complex life environments.

Dentin-like tissue formation and biomineralization by multicellular human pulp cell spheres in vitro

Introduction

Maintaining or regenerating a vital pulp is a preferable goal in current endodontic research. In this study, human dental pulp cell aggregates (spheres) were applied onto bovine and human root canal models to evaluate their potential use as pre-differentiated tissue units for dental pulp tissue regeneration.

Methods

Human dental pulp cells (DPC) were derived from wisdom teeth, cultivated into three-dimensional cell spheres and seeded onto bovine and into human root canals. Sphere formation, tissue-like and mineralization properties as well as growth behavior of cells on dentin structure were evaluated by light microscopy (LM), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).

Results

Spheres and outgrown cells showed tissue-like properties, the ability to merge with other cell spheres and extra cellular matrix formation; CLSM investigation revealed a dense network of actin and focal adhesion contacts (FAC) inside the spheres and a pronounced actin structure of cells outgrown from the spheres. A dentin-structure-orientated migration of the cells was shown by SEM investigation. Besides the direct extension of the cells into dentinal tubules, the coverage of the tubular walls with cell matrix was detected. Moreover, an emulation of dentin-like structures with tubuli-like and biomineral formation was detected by SEM- and EDX-investigation.

Conclusions

The results of the present study show tissue-like behavior, the replication of tubular structures and the mineralization of human dental pulp spheres when colonized on root dentin. The application of cells in form of pulp spheres on root dentin reveals their beneficial potential for dental tissue regeneration.

Three-year prospective clinical performance of a one-step self-etch adhesive and a nanofiller hybrid resin composite in Class V lesions

PURPOSE

This 3-year prospective clinical study evaluated the clinical performance of a one-step self-etching adhesive (Futurabond NR) in combination with a nanohybrid composite (Grandio) for the treatment of different Class V cavities.

METHODS

122 restorations were placed in 42 patients (mean age of 54 +/- 13.2 years) evaluated according to modified Ryge-criteria at baseline, 6 months, 1, 2 and 3 years. The lesions comprised 91 Class V non-caries cervical lesions (NCCL) and 31 Class V cavities due to caries or restoration replacement. While carious lesions as well as restoration replacement required preparation of dentin, it was not roughened in case of NCCL. Macro-mechanical retention with undercuts was not used. The statistical analysis was carried out based on Bonferroni adjusted McNemar test (global alpha = 0.05) including the criteria marginal adaptation, color match, surface texture, anatomical form, retention and clinical acceptance and pain. The occurrence of secondary caries, preoperative and postoperative sensitivity was also examined.

RESULTS

After 3 years of clinical service the restorations showed a significant deterioration of all studied parameters. After 3 years, 65% of the restorations were rated as excellent or acceptable in terms of clinical acceptance, 9% appeared tolerable and 26% were rated as not acceptable which mainly resulted from restoration losses. Within the observed timeframe the retention rate decreased to 75%, which means that 30 out of the 122 restorations were partially or completely lost. There was a difference in the 3-year retention rate of NCCL (71%) and the caries/restoration replacement group (87%) but it was not statistically significant.

Fear of dental treatment--an underrecognized symptom in people with impaired mental health

BACKGROUND

In industrialized countries, about 5% to 15% of all adults have a pathologically severe fear of dental treatment, and some 3% avoid going to the dentist altogether. The affected persons may, in turn, suffer from severe dental diseases and their psychosocial effects. Many people with dental phobia have other mental disorders as well. These facts motivated us to study the prevalence of fear of dental treatment in a group of patients being treated by our psychosomatic service.

METHOD

212 patients of our psychosomatic service and 95 healthy controls were studied with the Hierarchical Anxiety Questionnaire (HAQ) to determine the intensity of their fear of dental treatment. Mental disorders were diagnosed with structured clinical interviews according to DSM-IV.

RESULTS

Nearly one patient in three (30.5%, n = 64) suffered from pathologically severe fear of dental treatment; 24 of them (38.5%) had avoided visiting a dentist for longer than one year. Only 4 (4.2%) of the healthy controls were greatly afraid of dental treatment. Certain types of mental disorder were especially highly associated with fear of dental treatment: in particular, anxiety disorders (relative risk [RR] 7.44, 95% confidence interval [CI] 2.68-20.70) and depressive disorders (RR 4.92, 95% CI 1.73-14.05). Patients with post-traumatic stress disorder were affected most commonly: 34 (42%) of these patients were greatly afraid of dental treatment (RR 9.97, 95% CI 3.69-26.90). 75 of the 134 study participants who were afraid of dental treatment (56%) had cancelled a dental appointment, or failed to appear for a scheduled appointment, because of their fears.

CONCLUSION

Fear of dental treatment commonly accompanies certain types of mental disorder. Patients at high risk should be asked about such fears so that the problem can be recognized early and appropriately treated.

In vivo study of the initial bacterial adhesion on different implant materials

OBJECTIVE

Biofilm formation on implant materials plays a major role in the aetiology of periimplantitis. The aim of this study was to examine in vivo the initial bacterial adhesion on six different implant materials.

METHODS

The implant materials Ti-m, TiUnite®, ZiUnite®, ATZ-m, ATZ-s, TZP-A-m were tested using bovine enamel slabs as controls. All materials, fixed on splint systems, were examined after 30 min and 120 min of oral exposure. DAPI staining was used for quantitative analysis of the initially adherent microorganisms. Initial adherent microorganisms were visualised by fluorescence In situ-hybridisation (FISH) and quantified by confocal laser scanning microscopy (CLSM). The targets of the oligonucleotide probes were Eubacteria, Veillonella spp., Fusobacterium nucleatum, Actinomyces naeslundii and Streptococcus spp.

RESULTS

DAPI analysis showed that increasing the time of oral exposure resulted in an increasing amount of initial adherent bacteria. The highest level of colonisation was on ZiUnite®, with the lowest occurring on the bovine enamel, followed by Ti-m. This early colonisation correlated significantly with the surface roughnesses of the materials. FISH and CLSM showed no significant differences relating to total bacterial composition. However, Streptococcus spp. was shown to be the main colonisers on each of the investigated materials.

CONCLUSION

it could be shown that within an oral exposure time of 30 min and 120 min, despite the salivary acquired pellicle initial biofilm formation is mainly influenced directly or indirect by the material surface topography. Highly polished surfaces should minimise the risk of biofilm formation, plaque accumulation and possibly periimplantitis.

Nanotechnology and Its Role in Caries Therapy

The purpose of this review is to highlight recent nanotechnological developments for remineralization of incipient caries lesions as well as biomimetic strategies for enamel synthesis based on the application of nanotechnology. Analysis of in vitro data indicates that apatite nanoparticles might be effective in reversing lesion progression in the outer but not in the deeper part of early caries lesions. To control caries-induced demineralization, investigators have developed calcium and phosphate or fluoride ion-releasing nanofillers, enabling resin composites to release ions, if the pH decreases under in vitro conditions. Extensive in vitro investigations of apatite crystallization have been performed to mimic the hierarchical topology of natural enamel. Strategies for formation of highly organized biomineralized structures include oriented aggregation of nanocrystallites or the assembly of apatite nanoparticles mediated by organic scaffolds. Despite all these promising in vitro experiments, the effectiveness of such strategies for the control of demineralization processes as well as for caries therapy still needs validation by clinical studies.

A comprehensive method for determination of fatty acids in the initial oral biofilm (pellicle)

The acquired pellicle is a tenacious organic layer covering the surface of teeth, protecting the underlying dental hard tissues. Lipids account for about one quarter of the pellicle's dry weight and are assumed to be of considerable importance for their protective properties. Nevertheless, only preliminary information is available about the nature of lipids in the pellicle. Gas chromatography coupled with electron impact ionization mass spectrometry was used to establish a convenient analytical protocol in order to obtain a qualitative and quantitative characterization of a wide range of FAs (C(12)-C(22)). In situ biofilm formation was performed on bovine enamel slabs mounted on individual splints carried by 10 subjects. A modified Folch extraction procedure was adopted to extract the lipids from the detached pellicle, followed by transesterification to fatty acid methyl esters using methanol and concentrated hydrochloric acid. Tridecanoic and nonadecanoic acid were used as internal standards suitable and reliable for robust, precise and accurate measurements. The present study demonstrates, for the first time, a procedure based on a combination of innovative specimen generation and convenient sample preparation with sensitive GC-MS analysis for the determination of the fatty acid profile of the initial oral biofilm.

Potential association of paraoxonase-1, type 2 diabetes mellitus, and periodontitis

BACKGROUND

The association between periodontitis and systemic diseases, including cardiovascular diseases and diabetes mellitus (DM), has been recognized repeatedly. Paraoxonase-1 (PON-1) is involved in the prevention of atherosclerosis, and decreased enzyme activity in patients with DM has been shown. The aim of this study is to investigate a possible correlation between decreased PON-1 activity and the association between impaired glucose metabolism or DM and periodontitis.

METHODS

PON-1 phenotype distribution and enzyme activities were characterized by measuring the hydrolysis of phenylacetate and paraoxon in serum samples of 87 patients with type 2 DM and 46 patients with pre-DM showing impaired fasting plasma glucose and/or impaired oral glucose tolerance. The control group comprised 64 individuals with normal fasting plasma glucose and normal glucose tolerance. Altogether, 154 study participants were available for complete clinical periodontal examination.

RESULTS

No difference in periodontitis prevalence existed between the study groups. However, patients with DM had an increased risk of suffering from generalized periodontitis (adjusted odds ratio = 4.05; 95% confidence interval = 1.24 to 13.18; P = 0.02), and their PON-1 activity was reduced compared to controls. In contrast, patients with pre-DM showed neither an increased periodontitis risk nor an impaired paraoxonase status. PON-1 was not associated directly with periodontitis. Nevertheless, concerning patients with DM, poor oral hygiene, male sex, and PON-1 phenotype were found to be significant predictors for periodontitis extent.

CONCLUSIONS

Type 2 DM, but not a prediabetic state, increases the risk of generalized periodontitis. PON-1 status in patients with type 2 DM may contribute to this association.

Do edible oils reduce bacterial colonization of enamel in situ?

OBJECTIVE

Edible oils are an empiric approach for the prevention of oral diseases. The present in situ study investigated the effect of edible oils on initial bacterial colonization of enamel surfaces.

METHODS AND MATERIALS

Initial biofilm formation was performed on enamel specimens mounted on maxillary splints and carried by eight subjects. After 1 min of pellicle formation, rinses with safflower oil, olive oil and linseed oil were performed for 10 min. Application of chlorhexidine for 1 min served as positive control. Afterwards, the slabs were carried for 8 h overnight. Samples carried for 8 h without any rinse served as negative controls. The amount of adherent bacteria was determined by DAPI staining (4',6-diamidino-2-phenylindole) and live-dead staining (BacLight). Additionally, determination of colony forming units was performed after desorption of the bacteria. TEM evaluation was carried out after application of the rinses.

RESULTS

The number of adherent bacteria on control samples was 6.1 ± 8.1 × 10(5)/cm(2) after 8 h (DAPI). Fluorescence microscopic data from DAPI staining and live-dead staining as well as from the determination of CFU revealed no significant effects of rinsing with oils on the amount of adherent bacteria compared to the non-rinsed control samples. However, with chlorhexidine a significant reduction in the number of bacteria by more than 85 % was achieved (DAPI, chlorhexidine: 8.2 ± 17.1 × 10(4)/cm(2)). The ratio of viable to dead bacteria was almost equal (1:1) irrespective of the rinse adopted as recorded with BacLight. TEM indicated accumulation of oil micelles at the pellicle's surface and modification of its ultrastructure.

CONCLUSION

Rinses with edible oils have no significant impact on the initial pattern and amount of bacterial colonization on enamel over 8 h.

CLINICAL RELEVANCE

Rinses with edible oils cannot be recommended for efficient reduction of oral biofilm formation.

Microhardness of composite materials with different organic phases in deep class II cavities: an in vitro study

OBJECTIVE

This study compared the microhardness of three composite resins with different organic matrices in deep class II cavities.

MATERIALS AND METHOD

A total of 36 extracted molars were randomly assigned to six groups and standardized class II cavities were prepared. The cavity design comprised three steps in a mesiodistal direction with an increasing depth (2, 4, and 6 mm). Twelve cavities each were restored using Filtek Supreme (FS), Quixfil (QF), and Filtek Silorane (SI). The materials were applied in incremental layers of 2 mm and cured either with Halogen Translux Energy (HTE) (n=18) or LED Bluephase C8 (LED) (n=18). Subsequently, the specimens were cross-sectioned, and microhardness was determined in various depths and at two different distances from the matrix.

RESULTS

QF yielded the highest KHN microhardness values (92.67 ± 12.77), followed by FS (65.53 ± 19.52) and SI (57.67 ± 8.33). Composites cured with LED achieved higher KHN values. All materials showed the highest microhardness values within the superficial increments and at a distance of 1000 μm from the matrix.

Human saliva exposure modulates bone cell performance in vitro

Various situations encountered by a clinician during the daily routine including surgical periodontitis therapy, dental implant insertion, or tooth extraction involve the contact of saliva with the jaw bone. However, there are only sparse data concerning the influence of saliva on bone cells. Saliva specimens were incorporated within culture medium and administered to murine MC3T3 osteoblasts, of which the morphology (REM), proliferation (EZ4U), and differentiation (qRT-PCR, alkaline phosphatase activity, extracellular matrix calcification) were assessed. Simultaneously, the composition of saliva media was analyzed with respect to the content of lactoferrin, activities of classical salivary enzymes, and the ability to provoke inflammatory cytokine production (enzyme-linked immunosorbent assay) in MC3T3 osteoblasts. The morphology, proliferation, and expression of differentiation-associated genes were seriously handicapped by saliva contact. Saliva-touched cells exhibited less alkaline phosphatase but normal levels of extracellular matrix mineralization. Saliva-containing culture media featured physiological activities of salivary enzymes and considerable amounts of lactoferrin but almost completely lacked salivary alkaline phosphatase and unspecific proteases. Upon saliva incubation, MC3T3 osteoblasts did not release noteworthy levels of interleukin-1 beta or tumor necrosis factor alpha. Although saliva is generally considered to vitalize oral tissues, this study reveals that it harms osteoblast-like cells more due to the presence of salivary enzymes than by triggering of inflammation. This issue is clinically relevant because it broadens the understanding of the bone cell fate within the rather complex cosmos of the oral cavity thereby providing a basis for clinical decision making and treatment guidelines. It seems to be reasonable to restrict the contact period between saliva and bone.

Bone formation and neovascularization mediated by mesenchymal stem cells and endothelial cells in critical-sized calvarial defects

Bone represents a highly dynamic tissue whose development is strongly dependent on vasculogenic and angiogenic processes. Neovascularization also plays an important role in fracture healing and in tissue engineering applications aiming at restoring bone function. We have previously shown in a heterotopic subcutaneous implantation model of severe combined immunodeficiency (SCID) mice that implanted human umbilical vein endothelial cells (HUVECs) gave rise to the formation of a complex functional human neovasculature. In this study, we investigated the effect of HUVEC coimplantation on mesenchymal stem cell (MSC)-mediated bone regeneration in an orthotopic calvarial bone defect model in immunocompromised mice. For this purpose, human fibrin/Matrigel-immobilized HUVECs and MSCs were seeded alone or in combination into scaffolds consisting of decalcified processed bovine cancellous bone (Tutobone) and implanted into calvarial critical-sized defects. Our results show that implanted HUVECs formed complex three-dimensional networks of perfused human neovessels that were stabilized by recruiting perivascular cells. Neovessel formation was considerably higher in the coimplantation group, suggesting that implanted MSCs supported HUVEC-triggered neovascularization. In addition, implanted MSCs effectively supported bone formation in calvarial defects. However, the HUVEC-derived neovasculature did not improve MSC-triggered bone regeneration in this orthotopic critical-sized defect model.