Search

Purpose: Prevention and control of healthcare-associated infection (HCAI) are important within and beyond Europe. However, it is unclear which areas are considered important by HCAI prevention and control professionals. This study assesses the priorities in the prevention and control of HCAI as judged by experts in the field., Methods: A survey was conducted by the European Society of Clinical Microbiology and Infectious Diseases focussing on seven topics using SurveyMonkey ® . Through a newsletter distributed by email, about 5000 individuals were targeted throughout the world in February and March 2013. Participants were asked to rate the importance of particular topics from one (low importance) to ten (extraordinary importance), and there was no restriction on giving equal importance to more than one topic., Results: A total of 589 experts from 86 countries participated including 462 from Europe (response rate: 11.8 %). Physicians accounted for 60 % of participants, and 57 % had ten or more years' experience in this area. Microbial epidemiology/resistance achieved the highest priority scoring with 8.9, followed by surveillance 8.2, and decolonisation/disinfection/antiseptics with 7.9. Under epidemiology/resistance, highly resistant Gram-negative bacilli scored highest (9.0-9.2). The provision of computerised healthcare information systems for the early detection of outbreaks was accorded the top priority under surveillance. The prevention of surgical site and central line infections ranked highest under the category of specific HCAI and HCAI in certain settings. Differences between regions are described., Conclusion: These findings reflect the concerns of experts in HCAI prevention and control. The results from this survey should inform national and international agencies on future action and research priorities.

Background: When patients are admitted to an intensive care unit (ICU) their risk of getting an infection will be highly depend on the length of stay at-risk in the ICU. In addition, risk of infection is likely to vary over calendar time as a result of fluctuations in the prevalence of the pathogen on the ward. Hence risk of infection is expected to depend on two time scales (time in ICU and calendar time) as well as competing events (discharge or death) and their spatial location. The purpose of this paper is to develop and apply appropriate statistical models for the risk of ICU-acquired infection accounting for multiple time scales, competing risks and the spatial clustering of the data., Methods: A multi-center data base from a Spanish surveillance network was used to study the occurrence of an infection due to Methicillin-resistant Staphylococcus aureus (MRSA). The analysis included 84,843 patient admissions between January 2006 and December 2011 from 81 ICUs. Stratified Cox models were used to study multiple time scales while accounting for spatial clustering of the data (patients within ICUs) and for death or discharge as competing events for MRSA infection., Results: Both time scales, time in ICU and calendar time, are highly associated with the MRSA hazard rate and cumulative risk. When using only one basic time scale, the interpretation and magnitude of several patient-individual risk factors differed. Risk factors concerning the severity of illness were more pronounced when using only calendar time. These differences disappeared when using both time scales simultaneously., Conclusions: The time-dependent dynamics of infections is complex and should be studied with models allowing for multiple time scales. For patient individual risk-factors we recommend stratified Cox regression models for competing events with ICU time as the basic time scale and calendar time as a covariate. The inclusion of calendar time and stratification by ICU allow to indirectly account for ICU-level effects such as local outbreaks or prevention interventions.

Background: Observational studies claimed reducing effects of neuraminidase inhibitors (NI) on hospital mortality in patients with H1N1 influenza A. It has been criticized that such findings are prone to common and serious survival biases., Methods: With observational data from the FLU-CIN study group, multi-state and dynamic prediction models have been used to avoid such biases. The data included 1391 patients with confirmed pandemic influenza A/H1N1 infection collected during 2009-2010 in the UK. Due to their close relationship, the main outcome measures were hospital death and length of hospital stay., Findings: There is no direct effect of NI on the hospital death rate; the hazard ratio (HR) of NI was 1.03 (95%-CI: 0.64-1.66). The discharge rate is increased for NI patients (HR = 1.89 (95%-CI: 1.65-2.16)) indicating that NI-treated patients stay shorter in hospital than NI-untreated patients, on average 3.10 days (95%-CI: 2.07-4.14). We also showed that the initiation timing of NI treatment (≤ 2 days versus > 2 days after onset) made no difference on the effects on the hospital death and discharge hazards. The hazard ratios remain stable after adjusting for potential confounders measured at admission (such as comorbidities and influenza-related clinical symptoms)., Conclusions: The potential beneficial effect of NI on hospitalized patients in the UK is rather a reduction of the length of hospital stay than a reduction of the mortality rate. There seems to be no confounding by indication and no differences if NI is given early or late. Different effects could be present in other populations (such as non-hospitalized individuals) or countries. Careful interpretation of the effect on length of hospital stay is needed due to potentially different discharge policies of NI-treated and NI-untreated patients., Competing Interests: All authors have completed the Unified Competing Interest form and declare that MW and MS are academic partners in the European Union’s Innovative Medicines Initiative (IMI) funded COMBACTE (Combatting Bacterial Resistance in Europe) project (grant No 115523) which cooperates with partners from the European Federation of Pharmaceutical Industries and Associations. MW and MS have not received any support from industrial companies for the submitted work and have neither financial nor non-financial interests that may be relevant to the submitted work. This does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

Objectives: We provide a case-cohort approach and show that a full competing risk analysis is feasible even in a reduced data set. Competing events for hospital-acquired infections are death or discharge from the hospital because they preclude the observation of such infections., Study Design and Setting: Using surveillance data of 6,568 patient admissions (full cohort) from two Spanish intensive care units, we propose a case-cohort approach which uses only data from a random sample of the full cohort and all infected patients (the cases). We combine established methodology to study following measures: event-specific as well as subdistribution hazard ratios for all three events (infection, death, and discharge), cumulative hazards as well as incidence functions by risk factor, and also for all three events., Results: Compared with the values from the full cohort, all measures are well approximated with the case-cohort design. For the event of interest (infection), event-specific and subdistribution hazards can be estimated with the full efficiency of the case-cohort design. So, standard errors are only slightly increased, whereas the precision of estimated hazards of the competing events is inflated according to the size of the subcohort., Conclusion: The case-cohort design provides an appropriate sampling design for studying hospital-acquired infections in a reduced data set. Potential effects of risk factors on the competing events (death and discharge) can be evaluated., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Purpose: To evaluate the potential of two bone substitute materials and the influence of different healing periods in guided bone regeneration therapy of osseous defects around implants., Materials and Methods: Twenty-four edentulous patients received implants in the region of the lost lower incisors. Around two standardized osseous defects were created, treated either with a 50:50 mixture of PepGen P-15® and OsteoGraf®/N-700 (test group) or with BioOss® (control group), and covered with titanium membranes. After healing periods of 2, 4, 6, or 9 months, the implants were removed together with the surrounding bone and subsequently prepared for histological evaluations., Results: Defect depths in both groups showed a clinical reduction after intervention. The histologically measured distance from the implant shoulder to the first point of bone-implant contact (BIC) after treatment did not differ between the two groups. The healing time influenced the level of the first point of BIC, with a longer healing period producing a more coronal first point of BIC. A greater percentage BIC and a higher fraction of mineralized bone were found in the pristine bone area compared with the augmented defect area., Conclusion: It can be concluded that in the treatment of osseous defects around oral implants, both materials were equally effective bone substitute materials when used in combination with guided bone regeneration., (© 2014 Wiley Periodicals, Inc.)

Objective: The aim of the study was to evaluate the thermomechanical behavior of alumina-toughened zirconia (ATZ) oral implants in the artificial mouth and the fracture resistance (fracture load and bending moment) in a subsequent static fracture load test. The effects of abutment modification and different cyclic loadings were evaluated., Methods: A total of 48 implants were used. 24 implants were left as machined (Group A), and 24 implants were shape modified at the abutment (Group B). Groups were divided into three subgroups composed of 8 samples each (A1/B1: no cyclic loading; A2/B2: 1.2 million cycles; A3/B3: 5 million cycles). Subsequently, all implants were statically loaded to the point of fracture., Results: The implants showed the following survival rates after the artificial mouth: A2 and B2 100%; A3 and B3 87.5%. The following average fracture resistance values were found (fracture load [N]/bending moment [Nmm]): A1 (583/2907), B1 (516/2825), A2 (618/2737), B2 (550/3150), A3 (802/3784) and B3 (722/3809). After 5 million loading cycles a significant increase in fracture load and bending moment was found. Modification of the abutment significantly decreased the fracture load of implants without foregoing dynamic loading. However, the shape modification altered the lever arm. For that reason, a smaller load resulted in the same bending moment. Therefore, abutment modification had no significant influence on the fracture resistance of ATZ., Significance: Neither thermomechanical cycling in an aqueous environment nor modification of the abutment had a negative effect on the fracture resistance of ATZ., (Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

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.

Introduction: Zirconia posts can be used as an esthetic alternative to metal posts. Despite their advantages, there is a lack of information about the long-term performance of zirconia posts., Objectives: This retrospective clinical study examined the survival probability, clinical performance, and reasons for failure of teeth restored with zirconia posts after an observation period of up to 10 years., Materials and Methods: After a mean observation period of 10 years, clinical and radiographic examinations were carried out for a total of 64 posts in 45 patients. The posts received mainly either ceramic or direct composite buildups. All posts were adhesively cemented, after air abrasion with alumina particles or silica coating and silanization. The majority of the reconstructed teeth were used as abutments for metal ceramic or ceramic fixed dental prostheses. Kaplan-Meier analysis was employed to compute the survival probability of teeth restored with zirconia posts. Cox regression analysis was used to assess the risk of failure and to identify possible covariates., Results: During the follow-up period, a drop-out rate of 49.4 % was recorded. The survival probability for teeth with zirconia posts was 81.3 % after 10 years., Conclusion: Within the limits of this study, zirconia posts can be used for abutments that will be restored with ceramic restorations. However, due to the high patient drop-out rate, careful interpretation of the current results is suggested., Clinical Relevance: The present paper is the first 10-year clinical study on teeth restored with zirconia posts and could serve as a reference for future research. In addition, it provides long-term data about restorations already implemented by dental practitioners.

Background: To analyse whether the availability of written standards for management of mechanically ventilated patients and/or the existence of a surveillance system for cases of ventilation-associated pneumonia (VAP) are positively associated with compliance with 6 well-established VAP prevention measures., Methods: Ecological study based on responses to an online-questionnaire completed by 1730 critical care physicians. Replies were received from 77 different countries, of which the majority, i.e. 1351, came from 36 European countries., Results: On a cross-country level, compliance with VAP prevention measures is higher in countries with a large number of prevention standards and/or VAP surveillance systems in place at ICU level., Likewise, implementation of standards and VAP surveillance systems has a significant impact on self-reported total compliance with VAP prevention measures (both p < 0.001). Moreover, predictions of overall prevention measure compliance show the effect size of the availability of written standards and existence of surveillance system. For instance, a female physician with 10 years of experience in critical care working in a 15-bed ICU in France has a predicted baseline level of VAP prevention measure compliance of 63 per cent. This baseline level increases by 9.5 percentage points (p < 0.001) if a written clinical VAP prevention standard is available in the ICU, and by another 4 percentage points (p < 0.001) if complemented by a VAP surveillance system., Conclusions: The existence of written standards for management of mechanically ventilated patients in an ICU and the availability of VAP surveillance systems have shown to be positively associated with compliance with VAP prevention measures and should be fostered on a policy level.

Introduction: Risk factor analyses for nosocomial infections (NIs) are complex. First, due to competing events for NI, the association between risk factors of NI as measured using hazard rates may not coincide with the association using cumulative probability (risk). Second, patients from the same intensive care unit (ICU) who share the same environmental exposure are likely to be more similar with regard to risk factors predisposing to a NI than patients from different ICUs. We aimed to develop an analytical approach to account for both features and to use it to evaluate associations between patient- and ICU-level characteristics with both rates of NI and competing risks and with the cumulative probability of infection., Methods: We considered a multicenter database of 159 intensive care units containing 109,216 admissions (813,739 admission-days) from the Spanish HELICS-ENVIN ICU network. We analyzed the data using two models: an etiologic model (rate based) and a predictive model (risk based). In both models, random effects (shared frailties) were introduced to assess heterogeneity. Death and discharge without NI are treated as competing events for NI., Results: There was a large heterogeneity across ICUs in NI hazard rates, which remained after accounting for multilevel risk factors, meaning that there are remaining unobserved ICU-specific factors that influence NI occurrence. Heterogeneity across ICUs in terms of cumulative probability of NI was even more pronounced. Several risk factors had markedly different associations in the rate-based and risk-based models. For some, the associations differed in magnitude. For example, high Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were associated with modest increases in the rate of nosocomial bacteremia, but large increases in the risk. Others differed in sign, for example respiratory vs cardiovascular diagnostic categories were associated with a reduced rate of nosocomial bacteremia, but an increased risk., Conclusions: A combination of competing risks and multilevel models is required to understand direct and indirect risk factors for NI and distinguish patient-level from ICU-level factors.

Objectives: The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after thermo-mechanical fatigue., Materials and Methods: Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups (n=24/group). All teeth received an onlay preparation with a mesio-occlusal-distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerising resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98 N, 1.2 million cycles; 5°C/55°C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200× magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements., Results: Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays., Conclusions: Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique., Clinical Relevance: Clinical requirements of 100 μm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays. Superior internal fit was observed with the heat-press manufacturing method. The impact of present findings on the clinical long-term behaviour of differently fabricated all-ceramic onlays warrants further investigation., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In nested case-control studies, incidence density sampling is the time-dependent matching procedure to approximate hazard ratios. The cumulative incidence function can also be estimated if information from the full cohort is used. In the presence of competing events, however, the cumulative incidence function depends on the hazard of the disease of interest and on the competing events hazard. Using hospital-acquired infection as an example (full cohort), we propose a sampling method for nested case-control studies to estimate subdistribution hazard ratios. With further information on the full cohort, the cumulative incidence function for the event of interest can then be estimated as well.

Objectives: Due to morphological differences along the root canal, serious structural damage, or extensive endodontic preparation, cement thickness of luted fibre-reinforced composite (FRC) post systems can largely vary. This study aimed at evaluating the effects of a self-etch (Multilink Automix, MLA) and various self-adhesive resin cements (G-Cem, GCM; Maxcem Elite, MXE; RelyX Unicem, RLX; SmartCem 2, SMC) on the pull-out bond strengths of FRC posts to root canal dentine, and to compare the effects of different cementation thicknesses., Methods: 100 bovine incisor roots were embedded in acrylic resin and randomly assigned to two groups. Root canals of group 1 were prepared with RelyX Fiber Post drill size one (Ø 1.3mm), whereas in group 2 drill size three (Ø 1.9mm) was used to attain different cement thicknesses (thicknesses 1 and 2). Each group was then subdivided into five subgroups (n=10). RelyX Fiber Posts size one (Ø 0.70mm) were luted with the respective resin cements. All specimens were subjected to pull-out evaluation using a universal testing machine. Post surface areas covered with cement were measured by means of stereomicroscopy., Results: RLX revealed the significantly highest pull-out bond strengths in both groups (p<0.05), while MXE exhibited the significantly lowest pull-out bond strengths in group 2 (p<0.05). Main failure modes were determined as adhesive at the cement-post surface for all examined groups (except for SMC, group 2)., Conclusions: The different resin cements influenced the pull-out bond strengths, whereas the cement thickness itself was not responsible for any differences., Clinical Significance: Self-adhesive resin cements can provide an acceptable retention of FRC posts even in case of use with wider post space conditions., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Statement of Problem: Preparation designs and ceramic thicknesses are key factors for the long-term success of minimally invasive premolar partial coverage restorations. However, only limited information is presently available on this topic., Purpose: The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of ceramic premolar partial coverage restorations with different preparation designs and ceramic thicknesses., Material and Methods: Caries-free human premolars (n=144) were divided into 9 groups. Palatal onlay preparation comprised reduction of the palatal cusp by 2 mm (Palatal Onlay Standard), 1 mm (Palatal-Onlay-Thin), or 0.5 mm (Palatal Onlay Ultrathin). Complete-coverage onlay preparation additionally included the buccal cusp (Occlusal Onlay Standard; Occlusal Onlay Thin; Occlusal Onlay Ultrathin). Labial surface preparations with chamfer reductions of 0.8 mm (Complete-Veneer-Standard), 0.6 mm (Complete-Veneer-Thin), and 0.4 mm (Complete Veneer Ultrathin) were implemented for complete veneer restorations. Restorations were fabricated from a pressable lithium disilicate ceramic (IPS-e.max-Press) and cemented adhesively (Syntac-Classic/Variolink-II). All specimens were subjected to cyclic mechanical loading (F=49 N, 1.2 million cycles) and simultaneous thermocycling (5°C to 55°C) in a mouth-motion simulator. After fatigue, restorations were exposed to single-load-to-failure. Two-way ANOVA was used to identify statistical differences. Pair-wise differences were calculated and P-values were adjusted by the Tukey-Kramer method (α=.05)., Results: All specimens survived fatigue. Mean (SD) load to failure values (N) were as follows: 837 (320/Palatal-Onlay-Standard), 1055 (369/Palatal-Onlay-Thin), 1192 (342/Palatal-Onlay-Ultrathin), 963 (405/Occlusal-Onlay-Standard), 1108 (340/Occlusal-Onlay-Thin), 997 (331/Occlusal-Onlay-Ultrathin), 1361 (333/Complete-Veneer-Standard), 1087 (251/Complete-Veneer-Thin), 883 (311/Complete-Veneer-Ultrathin). Palatal-onlay restorations revealed a significantly higher fracture resistance with ultrathin thicknesses than with standard thicknesses (P=.015). Onlay restorations were not affected by thickness variations. Fracture loads of standard complete veneers were significantly higher than thin (P=.03) and ultrathin (P<.001) restorations., Conclusions: In this in vitro study, the reduction of preparation depth to 1.00 and 0.5 mm did not impair fracture resistance of pressable lithium-disilicate ceramic onlay restorations but resulted in lower failure loads in complete veneer restorations on premolars., (Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Purpose: Classic tissue engineering consists of three components: scaffold, cells, and growth or differentiation factors. Currently, expensive bone morphogenetic proteins are the most common substance used for hard tissue regeneration. An alternative could be gamma-aminobutyric acid/lactam (GABA-lactam) analogs., Materials and Methods: The effects of gabapentin-lactam, cis- and trans-8-tertbutyl-GABA-pentinlactam (trans-TB-GBP-L), and phenyl-GABA-lactam were tested in this study on ovine mesenchymal stem cell (MSC) proliferation. MSCs were selected from bone marrow aspirate concentrate by plastic adherence and amplified. Aliquots of the cells were incubated in medium, with four different concentrations of the GABA-lactam analogs dissolved in dimethyl sulfoxide. Cells in medium with and without dimethyl sulfoxide served as controls. Cell proliferation was tested with a nonradioactive assay. Before and after GABA-lactam analog influence, the MSC character was evaluated by the ability of the cells to differentiate into osteoblasts, chondrocytes, and adipocytes., Results: Proliferation was significantly increased under the influence of the analogs, depending on their concentration. MSCs cultured in 1 nmol/L trans-TB-GBP-L showed the highest proliferation rate. The MSC character was not altered., Conclusions: GABA-lactam analogs could be suited to stimulate MSC proliferation for tissue engineering applications. Further in vivo studies are necessary to evaluate the possible clinical potential of GABA-lactam analogs for hard tissue regeneration.

The aim of the present study was to evaluate the release of monomers from three bonding systems and to correlate it with their antibacterial effect. Three bonding systems (Optibond FL(®), Xeno III(®) and Clearfil™ Protect Bond) were tested after storage in ethanol 75 % and human saliva. Twenty samples (n = 10/medium) of each bonding material were prepared and polymerized according to the manufacturers' instructions. Each sample was stored in 1 ml of the respective storage medium. The medium was renewed after 24 h, 7 days, and 28 days and was analysed by LC-MS/MS for the release of substances. Additionally, the antibacterial effect of the unpolymerized components of each bonding system and their polymerized mixture was tested using agar disc-diffusion test with Streptococcus mutans. Only HEMA was found to be released. The amount of HEMA detected in the ethanol samples was significantly higher compared to the saliva samples (p < 0.0001). The release of HEMA was as follows: Clearfil™ Protect Bond < Optibond FL(®) < Xeno III(®.) According to the agar disc-diffusion test, all materials exhibited certain antibacterial activity. The release of HEMA from all tested materials even after storing in human saliva increases the concerns about their toxicity. Their antibacterial effect seems not be due to the release of substances.

Objectives: Purpose of this study was to investigate the effect of cleaning methods of glass ceramic specimens contaminated with saliva on tensile bond strength (TBS) to composite resin. Additionally, effect of water storage on bond strength was evaluated., Materials and Methods: Glass ceramic discs (IPS Empress, Ivoclar-Vivadent, FL) distributed among five groups (n = 28) were etched with hydrofluoric acid, silanized, contaminated with human saliva, and in group W rinsed with water, group WS additionally silanized, group E rinsed with water and cleaned with ethanol, and group ES additionally silanized. Group C served as a control without contamination. Plastic screws were bonded to the glass ceramic discs using Variolink II (Ivoclar-Vivadent). TBS was measured after 24 h and after 150 days of storage. Failure modes were examined. ANOVA was applied to explore group effect on TBS. Pair-wise comparisons were calculated., Results: The mean TBS [in megapascals] were for W 46 ± 14, WS 55 ± 8, E 48 ± 11, ES 52 ± 10, and C 50 ± 8 after 24 h, and W 39 ± 11, WS 53 ± 9, E 48 ± 8, ES 48 ± 11, and C 50 ± 8 after 150 days. After 150 days specimens of group W showed significantly lower TBS compared to group C (p = 0.05). Additional silanization in group WS led to a significant increase of TBS compared to specimens of group W (p = 0.003). Adhesive fractures were observed only in specimens without second application of silane., Conclusions: The cleaning of the contaminated glass ceramic surface by rinsing only did not result in a durable bond., Clinical Relevance: Pre-silanized glass ceramic restorations need to be rinsed and treated with a fresh layer of silane after saliva contamination.

The aim of this in vitro study was to evaluate the colour stability of bleaching after light activation with halogen unit, laser, LED unit or chemical activation up to 3 months after treatment. Four groups of teeth (n = 20) were bleached with Opalescence Xtra Boost (38% hydrogen peroxide) using four different methods: activation with halogen, LED, laser or chemical activation only. All teeth were bleached in one session for four times (4 × 15 min) and the colour was evaluated using a spectrophotometer at the following time points: before bleaching, immediately after bleaching, 1 day, and 1 and 3 months after the end of bleaching. Between the tested time points, the teeth were stored in 0.9% NaCl solution. Additionally, the temperature increase in the pulp chamber was measured using a measuring sensor connected to a computer. Bleaching with the halogen unit showed the highest colour change. Halogen unit, laser and chemical activation resulted in whiter teeth after 1 and 3 months compared to the colour after the end of the bleaching procedure (p ≤ 0.05). Three months after the end of bleaching, the shade changes observed were-halogen: 7.1 > chemical activation: 6.2 > LED: 5.4 > laser: 5.2. Halogen showed the highest temperature increase (17.39°C ± 1.96) followed by laser (14.06°C ± 2.55) and LED (0.41°C ± 0.66) (p < 0.0001). Chemical activation did not affect the temperature in the pulp chamber. The use of light activation did not show any advantages compared to chemical bleaching. Although halogen unit showed the higher shade's change, its use resulted also in the higher pulp temperature. According to the present findings, light activation of the bleaching agent seems not to be beneficial compared to bleaching without light activation, concerning the colour stability up to 3 months after bleaching and the pulp temperature caused during the bleaching procedure.

Objectives: To display and discuss the reasons and consequences of length and time-dependent bias. They might occur in presence of a time-dependent study entry or a time-dependent exposure which might change from unexposed to exposed., Study Design and Setting: Recalling the popular study of Oscar nominees and using a real-data example from hospital epidemiology, we give innovative and easy-to-understand graphical presentations of how these biases corrupt the analyses via distorted time-at-risk. Cumulative hazard plots and Cox proportional hazards models were used. We are building bridges to medical disciplines such as critical care medicine, hepatology, pharmaco-epidemiology, transplantation medicine, neurology, gynecology and cardiology., Results: In presence of time-dependent bias, the hazard ratio (comparing exposed with unexposed) is artificially underestimated. The length bias leads to an artificial underestimation of the overall hazard. When both biases coexist it can lead to different directions of biased hazard ratios., Conclusion: Since length and time-dependent bias might occur in several medical disciplines, we conclude that understanding and awareness are the best prevention of survival bias., (Copyright © 2012 Elsevier Inc. All rights reserved.)

In this study, we evaluate the accuracy and reproducibility of human tooth shade selection using a digital spectrophotometer. Variability among examiners and illumination conditions were tested for possible influence on measurement reproducibility. Fifteen intact anterior teeth of 15 subjects were evaluated for their shade using a digital spectrophotometer (Crystaleye, Olympus, Tokyo, Japan) by two examiners under the same light conditions representing a dental laboratory situation. Each examiner performed the measurement ten times on the labial surface of each tooth containing three evaluation sides (cervical, body, incisal). Commission International on Illumination color space values for L* (lightness), a* (red/green), and b* (yellow/blue) were obtained from each evaluated side. Examiner 2 repeated the measurements of the same subjects under different light conditions (i.e., a dental unit with a chairside lamp). To describe measurement precision, the mean color difference from the mean metric was used. The computed confidence interval (CI) value 5.228 (4.6598-5.8615) reflected (represented) the validity of the measurements. Least square mean analysis of the values obtained by examiners 1 and 2 or under different illumination conditions revealed no statistically significant differences (CI = 95%). Within the limits of the present study, the accuracy and reproducibility of dental shade selection using the tested spectrophotometer with respect to examiner and illumination conditions reflected the reliability of this device. This study suggests that the tested spectrophotometer can be recommended for the clinical application of shade selection.

Enterococcus faecalis (E. faecalis) is a Gram-positive bacterium, mostly recovered from root-filled teeth with persistent periapical lesions. Bacterial contamination of root canals inevitably results in interaction between E. faecalis and periapical tissues during the dynamic process of periapical inflammation. This study investigated the impact of heat-inactivated endodontic E. faecalis on the proliferation and the differentiation of ovine osteoblast-like cells, in an attempt to elucidate its putative enhanced pathogenicity mechanisms. Therefore, two different concentrations of a heat-inactivated endodontic E. faecalis isolate (2 × 10(6) or 2 × 10(8) CFU/ml) were incubated with ovine osteoblast-like cells for 7 and 14 days, respectively. Cells without antigen served as control. The effects of antigen on cell growth were evaluated by a proliferation assay (EZ4U). Furthermore, the assessment of alkaline phosphatase (ALP) activity, calcium deposition, and osteocalcin (OCN) gene expression through quantitative real-time PCR determined the degree of osteogenic cell differentiation. Scanning electron microscopy (SEM) was also performed to detect alterations in cell morphology. Interestingly, although highly concentrated E. faecalis increased cellular reproduction after 14 days, ALP activity and OCN gene expression decreased in an antigen concentration-dependent and incubation time-independent way. SEM images revealed E. faecalis adhesion on cells, a fact that might contribute to its virulence. These results suggest that E. faecalis stimulated cell multiplication, whereas it likely restrained cell differentiation of ovine osteoblast-like cells. In conclusion, the presence of E. faecalis in root canals may negatively affect periapical new bone formation, and thus, the healing of periapical lesions.

Background: Studies about the effect of grinding procedures as well as material thickness on the resistance of zirconia implant abutments are in short supply., Purpose: This study evaluated the effect of wall thickness as well as preparation on the resistance of zirconia implant abutments., Materials and Method: Sixty-four implants received titanium (group Ti) and zirconia abutments (groups Zr-8, Zr-18, and Zr-1). The abutments of group Zr-8 had a 0.8-mm wall thickness, whereas the wall thickness of group Zr-18 was reduced by preparation from 1 mm to 0.8 mm. The abutments of group Zr-1 had a wall thickness of 1 mm. Standardized maxillary central incisor metal crowns were cemented on all abutments. All specimens were then tested in a universal testing machine for their resistance to fracture before and after masticatory simulation (n = 8)., Results: The median resistance to fracture values (N) before and after aging were, respectively: group Ti: 500-504; group Zr-8: 487-491; group Zr-18: 490-451; and group Zr-1: 519-480. No significant effects of group, aging, or combinations were found (p > .05)., Conclusion: All tested abutments have the potential to withstand physiologic occlusal forces in the anterior region (> 200 N). The applicability of the results to other implant systems should be verified., (© 2011 Wiley Periodicals, Inc.)

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.

The aim of this study was to evaluate the effect of four different storage media on the elution of monomers from two composite materials. Samples (n = 10, diameter: 4.5 mm, thickness: 2 mm) of two different composite materials (Ceram X™ & Filtek™ Supreme XT) were stored after polymerization in four different media (NaCl, saliva, ethanol 75% & acetone) for 24 h, 7 days, and 28 days. From the storage medium of each tested time period, samples were prepared and analyzed by LC-MS/MS, for the elution of BisGMA, TEGDMA, HEMA, Bisphenol A, and two types of UDMA. No monomers were detected in the samples of Ceram X™, independently of the storage medium used. In the samples of Filtek™ Supreme XT, no Bisphenol A, HEMA, and UDMA 1 were found. BisGMA was detected only in the ethanol and acetone samples. The amount of BisGMA eluted in acetone was significant higher compared with ethanol 75% (p < 0.0001). TEGDMA was the only monomer that could be detected in all tested storage media. Storage in acetone resulted in higher release of TEGDMA when compared with other media. The amount of TEGDMA released in saliva was similar to the one released in ethanol 75%. It can be concluded that acetone is not a suitable medium for elution experiments and although ethanol 75% can simulate saliva concerning the elution of TEGDMA, it does not represent a laboratory substitute of saliva with respect to the elution of monomers like BisGMA., (Copyright © 2011 Wiley Periodicals, Inc.)

Objective: To test the "27 club" hypothesis that famous musicians are at an increased risk of death at age 27. Design Cohort study using survival analysis with age as a time dependent exposure. Comparison was primarily made within musicians, and secondarily relative to the general UK population., Setting: The popular music scene from a UK perspective., Participants: Musicians (solo artists and band members) who had a number one album in the UK between 1956 and 2007 (n = 1046 musicians, with 71 deaths, 7%)., Main Outcome Measures: Risk of death by age of musician, accounting for time dependent study entry and the number of musicians at risk. Risk was estimated using a flexible spline which would allow a bump at age 27 to appear., Results: We identified three deaths at age 27 amongst 522 musicians at risk, giving a rate of 0.57 deaths per 100 musician years. Similar death rates were observed at ages 25 (rate = 0.56) and 32 (0.54). There was no peak in risk around age 27, but the risk of death for famous musicians throughout their 20s and 30s was two to three times higher than the general UK population., Conclusions: The 27 club is unlikely to be a real phenomenon. Fame may increase the risk of death among musicians, but this risk is not limited to age 27.

Mathematical modelling of infectious diseases has gained growing attention in epidemiology during the last decades. The major benefits of simulating compartmental models are the prediction of the consequences of potential interventions, a deeper understanding of epidemic dynamics and clinical decision support. The main limitation is however that several parameters are based on uncertain expert guesses (default values) and are not estimated from the study data. In this paper we build a bridge between an extension of the well-known deterministic S-I-R (Susceptible-Infectious-Removed) model which can be described with differential equations and the stochastic counterpart which can be used for statistical inference if outbreak data on an individual level are available. The possibly time-dependent transmission rate as well as the (basic) reproduction number are the main epidemiological parameters of interest. Furthermore, one important type of heterogeneity is considered: individuals may vary due to their susceptibility, i.e., risk factors for infection may be investigated. A SAS computer program is provided to simulate outbreak data for this type of setting. The statistical analysis and typical challenges with epidemic data are discussed. Given data on an individual level, the Cox-Aalen survival model that is based on a multiplicative-additive hazard structure turned out to be a suitable tool for that purpose. The results give valuable information for epidemiologists, statisticians and public health researchers., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To evaluate the release of monomers from four different composite materials (Ceram X, Filtek Supreme XT, Tetric Flow, Tetric EvoCeram), polymerized using either halogen or LED unit., Methods: Ten specimens were made for each material/unit combination. Each specimen was stored in 1 ml 75% ethanol. The storage medium was renewed after 1, 7 and 28 days. Aliquots of this medium were analyzed by LC-MS/MS., Results: The effect of the curing unit on monomers' release differed significantly among the materials (P < 0.0001). The amount of BisGMA and TEGDMA released from Ceram X was not influenced by the unit used (P > 0.05). Curing with LED reduced the amount of Bisphenol A released from Ceram X compared to halogen. For Filtek Supreme XT, the type of unit exerted a significant effect on the elution of BisGMA (P < or = 0.05). LED curing resulted in a higher release of TEGDMA and UDMA compared to halogen (P < or = 0.05). For Tetric Flow, LED curing resulted in lower monomer release (P < 0.0001). For Tetric EvoCeram, the amounts of BisGMA, UDMA and Bisphenol A were higher when polymerizing with LED compared to halogen. The release of substances was more material dependent and less influenced by the curing unit used.

The aim of the study was to investigate changes in the micromorphologyl and microhardness of the enamel surface after bleaching with two different concentrations of hydrogen peroxide (HP) and carbamide peroxide (CP). Bovine enamel samples were embedded in resin blocks, and polished. Specimens in the experimental groups (n = 10) were treated with bleaching gels containing 10% CP, 35% CP, 3.6% HP, and 10% HP, respectively, for 2 h every second day over a period of 2 weeks. The gels had the identical composition and pH and differed only in their HP or CP content. The roughness and morphology of the enamel surface were analyzed using laser profilometry and SEM. Microhardness was measured using a Knoop hardness tester. The data were evaluated statistically. Specimens in the 10% HP group showed significantly higher roughness after bleaching compared to the control group (ΔRa, p = 0.01). Bleaching with 35% CP showed only a tendency to increase roughness (ΔRa, p = 0.06). Application of 10% CP or 3.6% HP had no significant influence on Ra. Enamel microhardness was significantly higher after application of 10% HP compared to the control (ΔMic = 8 KHN, p = 0.0002) and 35% CP (ΔMic = 20KHN, p = 0.01) groups. In summary, application of CP and HP showed only small quantitative and qualitative differences. In addition, the influence of bleaching procedure on the morphology and hardness of the enamel surface depended on the concentration of the active ingredients.

Objectives: Zirconia is a potential material for the fabrication of oral implants. The aim of this study was to evaluate the effects of cyclic loading and preparation on the fracture strength of a zirconia implant system., Materials and Methods: Forty-eight one-piece implants were divided into two groups of 24 implants: group A (without modification) and group B (1 mm chamfer preparation). Groups A and B were divided into three subgroups of eight implants each (1 = no artificial load, 2 = artificial load [98 N; 1.2 million loading cycles], and 3 = artificial load [98 N; 5 million loading cycles]). After completion of the loading, the fracture strength of each implant was determined in a universal testing machine. A two-way analysis of variance was used, the continuous response variable (fracture strength in Newtons) is modeled as a function of preparation, cycles, and the corresponding interaction as explanatory variables., Results: The mean fracture strength values obtained for the groups were: A1 (no preparation, no load) = 1928.73 N, A2 (no preparation, 1.2 million cycles) = 2044.84 N, A3 (no preparation, 5 million cycles) = 1364.50 N, B1 (preparation, no load) = 1221.66 N, B2 (preparation, 1.2 million cycles) = 967.11 N, and B3 (preparation, 5 million cycles) = 884.89 N. Fracture values were significantly different between subgroups A1 vs. A3 and B1 vs. B3. There was no significant difference between subgroups A1 vs. A2 and B1 vs. B2., Conclusions: Preparation as well as cyclic loading can decrease the fracture strength resistance of zirconia implants. Nevertheless, even the lowest values of mean fracture strength of the implants used in our study seem to withstand average occlusal forces even after an extended interval of artificial loading., (© 2011 John Wiley & Sons A/S.)

Antimicrobial resistance is threatening the successful management of nosocomial infections worldwide. Despite the therapeutic limitations imposed by methicillin-resistant Staphylococcus aureus (MRSA), its clinical impact is still debated. The objective of this study was to estimate the excess mortality and length of hospital stay (LOS) associated with MRSA bloodstream infections (BSI) in European hospitals. Between July 2007 and June 2008, a multicenter, prospective, parallel matched-cohort study was carried out in 13 tertiary care hospitals in as many European countries. Cohort I consisted of patients with MRSA BSI and cohort II of patients with methicillin-susceptible S. aureus (MSSA) BSI. The patients in both cohorts were matched for LOS prior to the onset of BSI with patients free of the respective BSI. Cohort I consisted of 248 MRSA patients and 453 controls and cohort II of 618 MSSA patients and 1,170 controls. Compared to the controls, MRSA patients had higher 30-day mortality (adjusted odds ratio [aOR] = 4.4) and higher hospital mortality (adjusted hazard ratio [aHR] = 3.5). Their excess LOS was 9.2 days. MSSA patients also had higher 30-day (aOR = 2.4) and hospital (aHR = 3.1) mortality and an excess LOS of 8.6 days. When the outcomes from the two cohorts were compared, an effect attributable to methicillin resistance was found for 30-day mortality (OR = 1.8; P = 0.04), but not for hospital mortality (HR = 1.1; P = 0.63) or LOS (difference = 0.6 days; P = 0.96). Irrespective of methicillin susceptibility, S. aureus BSI has a significant impact on morbidity and mortality. In addition, MRSA BSI leads to a fatal outcome more frequently than MSSA BSI. Infection control efforts in hospitals should aim to contain infections caused by both resistant and susceptible S. aureus.

Survival analysis has established itself as a major statistical technique in medical research. Applications in hospital epidemiology, however, are only beginning to emerge. One reason for this delay is that usually complete follow-up of patients in hospital is feasible. This overview discusses where survival techniques provide additional insight into hospital epidemiology, and where they are, in fact, needed even in the absence of right-censoring., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Objectives: Many studies disregard the time dependence of nosocomial infection when examining length of hospital stay and the associated financial costs. This leads to the "time-dependent bias," which biases multiplicative hazard ratios. We demonstrate the time-dependent bias on the additive scale of extra length of stay., Methods: To estimate the extra length of stay due to infection, we used a multistate model that accounted for the time of infection. For comparison we used a generalized linear model assuming a gamma distribution, a commonly used model that ignores the time of infection. We applied these two methods to a large prospective cohort of hospital admissions from Argentina, and compared the methods' performance using a simulation study., Results: For the Argentina data the extra length of stay due to nosocomial infection was 11.23 days when ignoring time dependence and only 1.35 days after accounting for the time of infection. The simulations showed that ignoring time dependence consistently overestimated the extra length of stay. This overestimation was similar for different rates of infection and even when an infection prolonged or shortened stay. We show examples where the time-dependent bias remains unchanged for the true discharge hazard ratios, but the bias for the extra length of stay is doubled because length of stay depends on the infection hazard., Conclusions: Ignoring the timing of nosocomial infection gives estimates that greatly overestimate its effect on the extra length of hospital stay., (Copyright © 2011 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.)

Objectives: The main objective was to study the impact of in-hospital bacteraemia caused by Staphylococcus aureus on mortality within 90 days after admission. We compared methicillin-resistant S. aureus (MRSA) with methicillin-susceptible S. aureus (MSSA)., Patients and Methods: The study population consisted of adult residents of Tayside, Scotland, UK, from 1 January 2005 to 30 September 2006 who had a new admission to Ninewells Hospital between 1 July 2005 and 30 June 2006. All patients (n = 3132) in the same wards as the patients infected with S. aureus were included. We addressed key weaknesses in previous studies by using a cohort design and applying a multistate model, which addressed the temporal dynamics. Critically, the model recognized that death and discharge from the hospital are competing events and that delay in discharge independently increases the risk of death., Results: The cohort included 3132 patients, of whom 494 died within 90 days after admission, 34 developed MRSA bacteraemia and 26 MSSA bacteraemia in the hospital. In comparison with patients without S. aureus bacteraemia, the death hazard was 5.6 times greater with MRSA [95% confidence interval (CI) 3.36-9.41] and 2.7 times greater with MSSA bacteraemia (95% CI 1.33-5.39). After adjustment for co-morbidity, hospitalization, age and sex, the death hazard was 2.9 times greater with MRSA (95% CI 1.70-4.88) and 1.7 times greater with MSSA bacteraemia (95% CI 0.84-3.47)., Conclusions: Time-dependent models such as the proposed multistate model are necessary to address the temporal dynamics of admission, infection, discharge and death. The impact of S. aureus bacteraemia on mortality should be considered on two levels: the burden of disease, i.e. nosocomial infection with S. aureus bacteraemia, and the burden of resistance to methicillin.

Background: Patients admitted to intensive-care units are at high risk of health-care-associated infections, and many are caused by antimicrobial-resistant pathogens. We aimed to assess excess mortality and length of stay in intensive-care units from bloodstream infections and pneumonia., Methods: We analysed data collected prospectively from intensive-care units that reported according to the European standard protocol for surveillance of health-care-associated infections. We focused on the most frequent causative microorganisms. Resistance was defined as resistance to ceftazidime (Acinetobacter baumannii or Pseudomonas aeruginosa), third-generation cephalosporins (Escherichia coli), and oxacillin (Staphylococcus aureus). We defined 20 different exposures according to infection site, microorganism, and resistance status. For every exposure, we compared outcomes between patients exposed and unexposed by use of time-dependent regression modelling. We adjusted results for patients' characteristics and time-dependency of the exposure., Findings: We obtained data for 119 699 patients who were admitted for more than 2 days to 537 intensive-care units in ten countries between Jan 1, 2005, and Dec 31, 2008. Excess risk of death (hazard ratio) for pneumonia in the fully adjusted model ranged from 1·7 (95% CI 1·4-1·9) for drug-sensitive S aureus to 3·5 (2·9-4·2) for drug-resistant P aeruginosa. For bloodstream infections, the excess risk ranged from 2·1 (1·6-2·6) for drug-sensitive S aureus to 4·0 (2·7-5·8) for drug-resistant P aeruginosa. Risk of death associated with antimicrobial resistance (ie, additional risk of death to that of the infection) was 1·2 (1·1-1·4) for pneumonia and 1·2 (0·9-1·5) for bloodstream infections for a combination of all four microorganisms, and was highest for S aureus (pneumonia 1·3 [1·0-1·6], bloodstream infections 1·6 [1·1-2·3]). Antimicrobial resistance did not significantly increase length of stay; the hazard ratio for discharge, dead or alive, for sensitive microorganisms compared with resistant microorganisms (all four combined) was 1·05 (0·97-1·13) for pneumonia and 1·02 (0·98-1·17) for bloodstream infections. P aeruginosa had the highest burden of health-care-acquired infections because of its high prevalence and pathogenicity of both its drug-sensitive and drug-resistant strains., Interpretation: Health-care-associated bloodstream infections and pneumonia greatly increase mortality and pneumonia increase length of stay in intensive-care units; the additional effect of the most common antimicrobial resistance patterns is comparatively low., Funding: European Commission (DG Sanco)., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: Alumina-toughened zirconia (ATZ) is a possible alternative material to titanium for oral implants. No data are available on the fracture strength of ATZ oral implants., Purpose: The purpose of this study was to examine one-piece implants made of ATZ ceramic under artificial loading conditions and to compare the fracture strength of these implants with implants fabricated from tetragonal zirconium dioxide poylcrystal (TZP)-A., Materials and Methods: A total of 72 implants, 48 ATZ implants (groups A and B) and 24 TZP-A implants (group C), were investigated. A chamfer preparation at the implant heads was performed on all implants of groups B and C. Eight implants of each group underwent 1.2 or five million thermomechanical loading cycles in the chewing simulator (load value: 98 N). Further eight implants of each group were not cyclic loaded. Finally, the fracture strength of all implants was determined using a universal testing machine., Results: No implant fractured during loading in the chewing simulator. All implants were placed in the universal testing machine to evaluate fracture strength. The mean fracture strength values±standard deviations for the implants without artificial loading were 1734±165 N (ATZ, no preparation), 1220±85 N (ATZ, with preparation), and 578±49 N (TZP-A, with preparation); 1489±190 N (ATZ, no preparation), 1064±121 N (ATZ, with preparation), and 607±57 N (TZP-A, with preparation) with 1.2 million loading cycles; and 1358±187 N (ATZ, no preparation), 1098±97 N (ATZ, with preparation), and 516±45 N (TZP-A, with preparation) with five million cycles. The ATZ implants showed significantly higher mean fracture strengths compared with the TZP-A implants. Modification of the implant head using diamond burs and increased loading time also led to a significant decrease in fracture strength., Conclusions: The ATZ implants showed an increased mechanical stability compared with the TZP-A. Modification of the implant head resulted in a decrease in fracture strength. However, within the limits of this in vitro investigation it can be concluded that ATZ implants will withstand functional loading over an estimated period of 20 years., (© 2010 John Wiley & Sons A/S.)

The aim of the study was to monitor changes in oral health and oral biofilm composition in vivo during an experiment simulating prehistoric lifestyle and diet and poor oral hygiene. Thirteen subjects lived for a period of 8 weeks under Neolithic conditions. The following clinical parameters were recorded before and after the project: gingival and plaque index (Löe and Silness, Acta Odontol Scand 21:533, 1963; Silness and Löe, Acta Odontol Scand 22:121-135, 1964), probing pocket depth, and bleeding upon probing. In addition, supragingival plaque samples were collected both before and after the project and were analysed quantitatively using multiplex fluorescence in situ hybridization and confocal laser scanning microscopy. The following plaque bacteria were evaluated: Streptococcus spp., Veillonella spp., Fusobacterium nucleatum, and Actinomyces naeslundii. The plaque index increased significantly from 1.12 up to 1.55 over the 8-week period (gingival index before, 0.46; after, 0.93; p < 0.05). A strong correlation of both indices was recorded before (r = 0.77) and after (r = 0.83) participation in the study. Each of the children in the study showed a progression of carious lesions and/or new areas of demineralisation. The probing pocket depth and bleeding upon probing were not affected. All subjects yielded an intra-individual shift in biofilm composition. The proportion of F. nucleatum decreased across all subjects. The proportion of Veillonella spp. increased among the children. Poor oral hygiene and change of diet lead to an increase in oral plaque and gingival inflammation. The inter-individual comparison indicated a shift in bacterial composition.