Direct and indirect effects of different dentifrices on the initial bacterial colonization of enamel in situ overnight.

OBJECTIVE: The aim of this study was to investigate the direct and indirect influence of fluoridated toothpastes and fluoride-free toothpaste with hydroxyapatite (HAP) as active ingredient on initial bacterial colonization on enamel in situ. METHODS: For this clinical-experimental pilot study, eight subjects were instructed to brush their teeth with three different toothpastes (Elmex® : 1400 ppm AmF, Meridol® : 1400 ppm AmF +SnF2, Karex® : HAP), using each for two consecutive days. As a control, brushing without toothpaste was performed. To evaluate bacterial colonization, subject wore splints with buccally placed bovine enamel platelets overnight. Two modes were tested. In a first pass (regimen A), the splints were inserted after toothbrushing to examine the indirect effects of the dentifrices. In order to investigate the direct effects, the specimens were brushed in situ in a second pass (regimen B). Biofilm formation was visualized and quantified using fluorescence microscopy (DAPI and BacLight) and transmission electron microscopy (TEM). RESULTS: For brushing regimen A (indirect effect of dentifrices), no statistical differences were detected between any of the tested dentifrices or the control. Likewise, no statistically significant differences were recorded for brushing regimen B (direct effect of dentifrices). Furthermore, no differences between the different brushing techniques were determined with regard to the ultrastructure of the overnight biofilm. CONCLUSION: Within the limitations of the present pilot study, it can be concluded that in patients with good oral hygiene, dentifrices and their chemical composition have no statistically significant effect on the initial bacterial colonization of enamel platelets in situ, irrespectively of the mode of application.

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.

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.

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.

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.