Andreas Braun

Short‐term clinical effects of adjunctive antimicrobial photodynamic therapy in periodontal treatment: a randomized clinical trial

OBJECTIVE The aim of this study was to assess the effect of adjunctive antimicrobial photodynamic therapy (aPDT) in chronic periodontitis. MATERIAL AND METHODS Twenty patients with untreated chronic periodontitis were included. All teeth received periodontal treatment comprising scaling and root planing. Using a split-mouth design, two quadrants (test group) were additionally treated with aPDT. Sulcus fluid flow rate (SFFR) and bleeding on probing (BOP) were assessed at baseline, 1 week and 3 months after treatment. Relative attachment level (RAL), probing depths (PDs) and gingival recession (GR) were evaluated at baseline and 3 months after treatment. RESULTS Baseline median values for PD, GR and RAL were not different in the test group and control group. Values for RAL, PD, SFFR and BOP decreased significantly 3 months after treatment in the control group (median delta RAL: -0.35 mm, inter-quartile range: 0.21 mm), with a higher impact on the sites treated with adjunctive aPDT (median delta RAL: -0.67 mm, inter-quartile range: 0.36 mm, p<0.05). GR increased 3 months after treatment with and without adjunctive aPDT (p<0.05), with no difference between the groups (p>0.05). CONCLUSIONS In patients with chronic periodontitis, clinical outcomes of conventional subgingival debridement can be improved by adjunctive aPDT.

The possibility of detecting subgingival calculus by laser-fluorescence in vitro

Abstract The aim of the present study was to investigate laser-fluorescence effects on the root surface. The possibility of detecting subgingival calculus should be evaluated to control complete calculus removal after scaling and root planing. Twenty freshly extracted human teeth, partially covered with calculus on the root surface, were fixed on a translation stage. The specimens were irradiated by light from a laser source (diode laser, <1 mW) with a wavelength of 655 nm using the Diagnodent™-system. To simulate the conditions in a periodontal pocket during the measurement procedure, the teeth were covered by a layer of physiological saline solution or blood in order to determine the influence of different inflammatory fluids. The root surface was scanned on a line of about 1 cm in steps of 0.5 mm. The start and end was marked by a notch. The results of the laser-fluorescence detection were compared to clinical and histological findings. Clinically apparent calculus on the root surface was always accompanied with a statistically significant increase of laser-fluorescence values (p < 0.05). These values were not influenced by the different fluids (p < 0.05). The laser-fluorescence values were reproducible (p > 0.05). After scaling, when no debris remained at the root surface, laser-fluorescence values decreased significantly (p < 0.05). The histological findings supported the clinical results. In conclusion, the present study indicates that laser-fluorescence values on the root surface are strongly correlated to the presence of calculus. This fluorescence effect can basically be used to develop a new detecting system for subgingival calculus in periodontal pockets.

Evaluation of selective caries removal by a fluorescence feedback-controlled Er:YAG laser in vitro

Aim: To establish a fluorescence threshold level that could guide a therapeutic Er:YAG laser through a caries lesion to determine a therapeutic endpoint of caries removal. Materials and Methods: A total of 65 extracted human teeth, 35 with dentine caries and 30 healthy, were used for this study. An Er:YAG laser system that emitted at a wavelength of 2.94 µm was used. The laser was equipped with a laser fluorescence feedback system, excitation wavelength 655 nm, to control the irradiation by the Er:YAG laser. The evaluated threshold levels of the fluorescence feedback system were 3, 7, 8, 10, 12, 15 and 20. After treatment the teeth were prepared for histological staining according to the method of Brown and Brenn for the identification of bacteria. The specimens were subjected to a quantitative evaluation of residual bacteria on the treated dentine surface. In addition, the internal fluorescence of dentine and potential fluorescence changes of dentine after laser irradiation were evaluated. Results: About 80% of the irradiated dentine surface showed residual bacteria with threshold levels of 20, 15, 12, and 10. Residual bacteria were not found with threshold levels of 7 and 3. The study revealed a significant increase in dentine fluorescence after laser irradiation. Conclusion: The results of the present in vitro study indicate that a fluorescence threshold level of 7 or 8 units can guide an Er:YAG laser to a complete removal of carious dentine.

Phylogeny and life habits of Early Arthropods——Predation in the Early Cambrian Sea

Abstract We investigated two new arthropods from the Maotianshan-Shale fauna of southern China in the course of our research on life strategies, particularly predation, in Early Cambrian marine macrofaunal biota. One form clearly belongs to the so-called “great-appendage” arthropods, animals that were, most likely, active predators catching prey with their first pair of large, specialized frontoventral appendages. Based on this, we hypothesize that the new species and many others, if not all of the “great-appendage” arthropods were derivatives of the chelicerate stem lineage and not forms having branched off at different nodes along the evolutionary lineage of the Arthropoda. Rather, we consider the “great-appendage” arthropods as belonging to a monophyletic clade, which modified autapomorphically their first pair of appendages (antennae in general arthropod terminology) into raptorial organs for food capture. The second new form resembles another Maotianshan-Shale arthropod. Fuxianhuia protensa, in shari...

Calculus removal and the prevention of its formation

Periodontitis is strongly associated with the presence of dental calculus on root surfaces. Although the rough calculus surface may not in itself induce inflammation in the adjacent periodontal tissues, dental calculus serves as an ideal substrate for subgingival microbial colonization. Therefore, causerelated anti-infective therapy aims to eliminate the microbial biofilm and calcified deposits from the diseased root surfaces by means of root surface debridement. Over the past 50 years, a large number of clinical and laboratory studies have been performed to determine the efficacy of calculus removal from diseased root surfaces by various methods. These studies aimed to determine whether complete removal of subgingival calculus by root surface debridement is possible. They also evaluated the importance of operator experience in the effectiveness of calculus removal. Possible differences in efficacy between hand tools and power-driven instruments or lasers have been investigated. The impact of tooth and site characteristics, such as probing depths, tooth type, tooth surfaces and furcation areas, has also been evaluated. In addition, side-effects such as unintentional root substance removal and patient discomfort have been assessed. This review focuses on the composition and formation of calculus, its significance for the disease process, the methods available for calculus removal, and prevention of its formation.

Cyanobacterial blooms as the cause of a Pleistocene large mammal assemblage

Abstract We investigated the petrography and biochemistry of varved sediments from a Pleistocene mass occurrence of fossil vertebrates in the lake basin of Neumark-Nord (Sachsen-Anhalt, Germany). The carbonate portions of the varves appear to be cyanobacterial layers that have been decomposed by benthic bacteria. The biochemical results obtained by absorption spectroscopy and RP-HPLC with UV-detection show that pigments, and probably toxins, characteristic for cyanobacteria are preserved in the sediment. The results of this study indicate the presence in the lake of large amounts of toxic cyanobacteria that probably occurred in seasonal blooms. It seems likely that these toxic cyanobacterial blooms caused the mass death of the large mammals preserved at the Neumark-Nord locality. This model may explain comparable lithologies and vertebrate occurrences in other Tertiary lake sediments such as the Messel oil shale.

Fluorescence‐controlled Er:YAG laser for caries removal in permanent teeth: a randomized clinical trial

The aim of this randomized clinical study was to compare the efficacy of a fluorescence-controlled erbium-loaded yttrium aluminum garnet (Er:YAG) laser with conventional bur treatment for caries therapy in adults. Twenty-six patients with 102 carious lesions were treated using either the Er:YAG laser, at threshold levels of 7, 8, 9, and 10 [U], or rotary burs. Both techniques were applied to each lesion at separate locations. After treatment, dentine samples were obtained using a carbide bur. The viable counts of Streptococcus mutans (SM) and lactobacilli (LB) [expressed as colony-forming units (log10 CFUs)], treatment time, pain, vibration, and sound intensity were determined. The median numbers of CFUs for SM and LB were not statistically different between laser and bur treatment at threshold levels 7 and 8 [U]. At threshold levels 9 and 10 [U], the median number of CFUs for LB [1.11 (range: 0.00-2.04)] were significantly higher following laser treatment than following bur treatment [0.30 (range: 0.00-0.60)]. The results indicate that treatment with a fluorescence-controlled Er:YAG laser at threshold levels of 7 and 8 removed caries to a level similar to that achieved using conventional bur treatment, with clinically irrelevant amounts of remaining bacteria. Although more time consuming, laser treatment provided higher patient comfort than bur treatment.

The Influence of the Calibration Mode of a Laser Fluorescence Device on Caries Detection

The aim of the present study was to assess the influence of the calibration mode of a laser fluorescence measurement device on caries detection. While positioning the probe on an occlusal carious lesion or stained fissure using a clamp, the occlusal surface of each of 62 teeth was covered with a light-body silicone impression material to facilitate a reproducible probe position. Then, measurements of the occlusal lesions were performed after standard and individual calibration at four non-carious areas on the buccal surface of each tooth. Mean laser fluorescence values of the occlusal reading point following standard calibration were about 4–5 units higher compared to values measured after individual calibration. After 1 week, readings after both standard and individual calibration were not different from baseline values (p > 0.05). During individual calibration, a mean range of about 2 units could be observed when comparing the readings of the occlusal reading point with respect to the four different areas of each buccal surface. The present study indicates that laser fluorescence readings are dependent on the mode of calibration. Moreover, for individual calibration, the probe position has to be recorded carefully. It is suggested that the same mode of calibration should always be used, when employing laser fluorescence measurements for longitudinal caries monitoring.

Laser fluorescence measurements compared to electrical resistance of residual dentine in excavated cavities in vivo.

It has been suggested that laser fluorescence close to the dental pulp shows higher values than more distant measurements. The aim of this study was to assess fluorescence on the cavity floor and to correlate these measurements with electrical resistance as a measure of residual dentine thickness. Thirty carious lesions were excavated with a bur. The endpoint of caries removal was determined by visual, tactile and auditory means. Fluorescence was measured with the Diagnodent device and with the fluorescence feedback system of a therapeutic Er:YAG laser. Electrical resistance of the residual dentine (Prepometer units, PU) was measured with a proprietary device. Significant differences were observed between the fluorescence systems (p < 0.05). For Diagnodent, a decrease of electrical resistance of the residual dentine resulted in an increase of the fluorescence values of 2.99 units/PU (95% CI = 2.00–3.97) and an increase of 0.30 units/PU (95% CI = 0.19–0.40) for the fluorescence feedback system. For zero electrical resistance, a predicted maximum value of 51.5 units (95% CI = 41.3–61.7) was calculated for the Diagnodent and 5.1 units (95% CI = 4.1–6.2) for the feedback system. The study indicates that using the suggested detection cut-off with the Diagnodent device may be not suited to assess the endpoint of caries removal close to the dental pulp. Employing the Key Laser III, values up to 6 units might be caused solely by close proximity to the pulp, which should be considered when caries removal by laser is controlled by laser fluorescence feedback.

First Early Cambrian Radiolaria

Abstract Radiolarian skeletons are known from a limestone concretion collected from a black shale succession and from black cherts of the Yangtze Platform, China. Both occurrences are of earliest Cambrian age. The findings, reported in this paper, represent the oldest known fossil Radiolaria. Their spherical skeletons display a morphology typical of spherical radiolarians from Ordovician and younger faunas. This occurrence of radiolarians with radial symmetry and, most probably, a planktonic lifestyle can now be traced back into the earliest Cambrian. Thus, radiolarians have been part of the early oceanic plankton and likely played a significant role in the silica cycle of the oceans along with siliceous sponges.