Mareike Warkentin

Section plane selection influences the results of histomorphometric studies: the example of dental implants

Abstract Objectives: This study was designed to determine and statistically analyze bone-to-implant contact (BIC) values for human specimens segmented in at least two different locations. Materials and methods: Samples of human bone with fractured osseointegrated implants were obtained from six patients. Sections were prepared, dehydrated, and resin infiltrated. Undecalcified bone sections were produced using the thin-section technique according to Donath, ultimately obtaining a section thickness of approximately 20 μm. Fifteen specimens were available for histomorphometry. The bone sections were digitized and analyzed. The bone-to-metal contact (BMC) parameter was determined histomorphometrically. The BMC was returned in terms of the visibly bone-covered implant surfaces as a percentage of the total implant surface shown. Results: The values obtained for the six implants were arranged as six maximum-distance pairs and tested for significance using the t-test for dependent samples. The mean difference in BIC was 11.69±9.79%. The two-sided test showed a significant difference (p=0.033). Conclusion: The accidental or deliberate choice of section plane for a bone-implant block has an influence on the BIC value. To make BIC values more comparable, a standardization of section planes is desirable.

Experiments on the mechanism of underwater hearing

Abstract Conclusion: The findings suggest that underwater sound perception is realized by the middle ear rather than by bone conduction, at least in shallow water conditions. Objective: To prove whether underwater sound perception is effected by bone conduction or by conduction via the middle ear. Methods: Five divers, breathing through snorkels, were tested in a swimming pool, to determine whether a sound was louder when the acoustic source placed was in front of the head in comparison with a lateral application facing the ear region. The second experiment investigated whether sound perception is influenced by ear protection plugs in underwater conditions. Also, the effect of a 5 mm thick neoprene hood was determined, with and without an additional perforation in the ear region. Results: Sounds were louder when applied from a position laterally facing the ear, louder without than with a protection plug, louder without than with a neoprene hood on, and louder when the neoprene hood had a perforation in the region of the ear than with an intact hood.

Dental implants and immediate loading: multivariate analysis of success factors.

OBJECTIVES The authors had for aim to examine factors potentially influencing the success of immediate implant placement and loading. MATERIALS AND METHODS One hundred and ninety-five consecutive patients (16.5 to 80.4 years of age) were provided with 310 prostheses supported by 896 immediately loaded implants. The mean follow-up was 27.5 months. Univariate and multivariate Cox regression was performed to analyze potential modifiers of implant success. RESULTS The overall implant success rate was 96.7%. The statistically significant modifiers of success on multivariate analysis (P<0.05) were duration of functional use (P<0.001), type of superstructure (P<0.001), implant-abutment connection (P<0.001), and maxilla versus mandible (P=0.026). None of the other investigated factors (age, gender, implant location/design/length) were statistically significant modifiers of success. DISCUSSION Our study results demonstrate high success rates for immediately loaded implants whatever types and superstructure used. Prosthetic designs and their implementation have a significant effect on the success rate of implant-supported restoration, with adjusted hazard ratios of up to 51. Maxilla versus mandible was the only significant non-external modifier when using an adjusted hazard ratio of 2.75.

Peri-implantitis cleaning instrumentation influences the integrity of photoactive nanocoatings

OBJECTIVE To determine in vitro the loss of integrity caused on photocatalytic anatase coated implant surfaces by clinical instrumentation through changes in surface topography and loss of functionality. METHODS Anatase-coated titanium discs were treated with diamond burs, polishers, plastic and metal hand instruments, air scaler and air flow devices. The pressure exerted through instrumentation was measured online. Surface topography was evaluated through scanning electron microscopy and contact profilometry, surface function through hydrophilization capacity upon UV-A activation. RESULTS Treatment with diamond burs and instruments with metal tips resulted in an increase of roughness. Use of silicone polishers led to smoothening, which was more pronounced on the anatase surface. Plastic instruments, the air abrasive system and rubber cups left the surfaces intact. Functionality was partially lost on surfaces subjected to hand instruments and completely lost upon diamond burs and silicone polishers. SIGNIFICANCE The integrity of functional nanocoatings depends on the applied instrumentation. Air flow device, rubber cup with polishing paste and plastic tipped instruments prevent damage on these nanosurfaces and may be preferably used when decontaminating anatase and other nanocoatings in a clinical setting.

Can nasal decongestants improve eustachian tube function

Objective To evaluate the effect of nasal decongestants on eustachian tube (ET) opening. Study design A prospective nonrandomized study. Setting A tertiary referral center. Patients Twenty-four patients (44 ears) with intact eardrums, 39 patients (43 ears) having a noninfected eardrum defect, and six patients with an upper airway infection. Interventions Nasal or intratympanal (in perforated ears) application of a nasal decongestant (xylometazoline 0.1%). Main outcome measures Change of tube opening quality (yes or no; better or worse) measuring tube opening parameters (pressure, latency) using the Estève method and pressure equalization tests (swallowing at negative and positive external ear canal pressures). Results In most cases, nasal decongestion or intratympanal use of decongestants have no effect on ET opening. Improvement in tube opening is rather an exception and, in a minority of patients, a reduced ET function was evident. Conclusion Our acute studies revealed no improvement in eustachian ventilatory tube function with the administration of nasal decongestants.

No influence of simultaneous bone-substitute application on the success of immediately loaded dental implants: a retrospective cohort study.

Abstract Purpose: To examine the influence of bone-substitute application during implantation on the success of immediately placed and loaded dental implants. Materials and methods: A total of 147 consecutive patients (age, 16.5–80.4 years) were provided with 696 immediately loaded implants. The mean follow-up time was 34.1 months. Of these implants, 50.4% (n=351) were immediately placed into extraction sockets. A total of 119 implants were added by simultaneous bone-substitute application (NanoBone, Artoss GmbH, Rostock Germany), whereas the other implants were placed in healed bone. Univariate and multivariate analysis was performed using IBM SPSS V.20. Results: The overall implant success rate was 96.1%. Implants with simultaneous bone replacement had a hazard ratio of 0.877 (p=0.837); 95% CI, 0.253–3.04). Factors found to be statistically significant modifiers of success on multivariate analysis (p<0.05) included type of superstructure (p<0.001), implant-abutment connection (p<0.001), membrane use (p=0.010), and jaw (p=0.026). None of the other factors investigated were significant modifiers. Conclusions: The present study demonstrates high success rates for immediately loaded implants and their superstructures independent of the simultaneous application of bone substitute. The declared aim of socket preservation, the prevention avoiding bone loss, is achieved in the immediate implant placement scenario under immediate-loading conditions.

Flexible Automation System for Determination of Elemental Composition of Incrustations in Clogged Biliary Endoprostheses Using ICP-MS

Automation systems are well established in industries and life science laboratories, especially in bioscreening and high-throughput applications. An increasing demand of automation solutions can be seen in the field of analytical measurement in chemical synthesis, quality control, and medical and pharmaceutical fields, as well as research and development. In this study, an automation solution was developed and optimized for the investigation of new biliary endoprostheses (stents), which should reduce clogging after implantation in the human body. The material inside the stents (incrustations) has to be controlled regularly and under identical conditions. The elemental composition is one criterion to be monitored in stent development. The manual procedure was transferred to an automated process including sample preparation, elemental analysis using inductively coupled plasma mass spectrometry (ICP-MS), and data evaluation. Due to safety issues, microwave-assisted acid digestion was executed outside of the automation system. The performance of the automated process was determined and validated. The measurement results and the processing times were compared for both the manual and the automated procedure. Finally, real samples of stent incrustations and pig bile were analyzed using the automation system.

Fast corroding, thin magnesium coating displays antibacterial effects and low cytotoxicity

Abstract Bacterial colonisation and biofilm formation are characteristics of implant-associated infections. In search of candidates for improved prosthetic materials, fast corroding Mg-based coatings on titanium surfaces were examined for their cytotoxic and antimicrobial properties. Human osteoblasts and Staphylococcus epidermidis were each cultured on cylindrical Ti samples coated with a thin layer of Mg/Mg45Zn5Ca, applied via magnetron sputtering. Uncoated titanium samples served as controls. S. epidermidis was quantified by counting colony forming units. The biofilm-bound fraction was isolated via ultrasonic treatment, and the planktonic fraction via centrifugation. Biofilm-bound S. epidermidis was significantly decreased by approximately four to five orders of magnitude in both Mg- and Mg45Zn5Ca-coated samples after seven days compared to the control. The osteoblast viability was within the tolerance threshold of 70% stated in DIN EN ISO 10993-5:2009-10 for Mg (~80%) but not for Mg45Zn5Ca (~25%). Accordingly, Mg-coated titanium was identified as a promising candidate for an implant material with antibacterial properties and low cytotoxicity levels. The approach of exploiting fast corrosion contrasts with existing methods, which have generally focused on reducing corrosion.

Materialographische Untersuchungen an Dentalwerkstoffen

Kurzfassung Aufgrund der demographischen Entwicklung steigt der Bedarf an geeigneten Werkstoffen und Biomaterialien für die Zahnerhaltung und auch für den Zahnersatz kontinuierlich. Im Fokus stehen hierbei Werkstoffe, die aufgrund ihrer physikochemischen, mechanischen und biologischen Eigenschaften die Qualität und Langlebigkeit in den Bereichen der minimalinvasiven Prophylaxe, Füllungstherapie, zahnärztlichen Prothetik und Implantologie signifikant verbessern. Nur durch die Kombination verschiedener mikroskopischer Untersuchungsverfahren ist es möglich, die Struktur-Eigenschaftskorrelation detailliert zu untersuchen und zu charakterisieren. Somit können die Funktionalitätsparameter der Werkstoffe optimiert werden, um dentale Werkstoffe mit optimierten Eigenschaften zu entwickeln.

In vitro aging behavior of dental composites considering the influence of filler content, storage media and incubation time

Objective Over time dental composites age due to mechanical impacts such as chewing and chemical impacts such as saliva enzymes and food ingredients. For this research, the focus was placed on chemical degradation. The objective of this study was to simulate hydrolysis by using different food simulating liquids and to assess their impact on the mechanical parameter Vickers microhardness (MHV) and the physicochemical parameter contact angle (CA). Methods Specimen of three composites (d = 6 mm, h = 2 mm; n = 435) classified with respect to their filler content (wt%), namely low-filled, medium-filled and highly-filled, were stored for 0, 14, 30, 90 and 180 days in artificial saliva (pH 7), citric acid (pH 3; pH 5), lactic acid (pH 3; pH 5) and ethanol (40%vol; 60%vol) and assessed regarding to MHV and CA. Statistics: Kruskal-Wallis test, stepwise linear regression, bivariate Spearman Rank Correlation (p < 0.05). Results While stored in artificial saliva, acid and ethanol the CA decreased especially for the low- and medium-filled composites. It was shown that rising the filler content caused less surface changes in the CA. Storage in ethanol led to a significant decrease of MHV of all composites. Regression analysis showed that the effect of in vitro aging on MHV was mainly influenced by the composite material and therefore by filler content (R2 = 0.67; p < 0.05). In contrast, the CA is more influenced by incubation time and filler content (R2 = 0.2; p < 0.05) leading to a higher risk of plaque accumulation over time. Significance: In vitro aging showed significant changes on the mechanical and physicochemical properties of dental composites which may shorten their long-term functionality. In conclusion, it can be stated, that the type of composite material, especially rising filler content seems to improve the materials’ resistance against the processes of chemical degradation.