Antimicrobial efficiency and cytocompatibility of different decontamination methods on titanium and zirconium surfaces.

OBJECTIVES: The purpose of this study was to investigate the efficiency of different implant-decontamination methods regarding biofilm modification and potential cytotoxic effects. Therefore, the amount of biofilm reduction, cytocompatibility, and elementary surface alterations were evaluated after decontamination of titanium and zirconium surfaces. MATERIAL AND METHODS: Titanium and zirconium disks were contaminated with a newly developed high-adherence biofilm consisting of six microbial species. Decontaminations were performed using titanium curette, stainless steel ultrasonic scaler (US), glycine (GPAP) and erythritol (EPAP) powder air-polishing, Er:YAG laser, 1% chlorhexidine (CHX), 10% povidone-iodine (PVI), 14% doxycycline (doxy), and 0.95% NaOCl solution. Microbiologic analysis was done using real-time qPCR. For assessment of cytocompatibility, a multiplex assay for the detection of cytotoxicity, viability, and apoptosis on human gingival fibroblasts was performed. X-ray photoelectron spectroscopy (XPS) was used to evaluate chemical alterations on implant surfaces. RESULTS: Compared with untreated control disks, only GPAP, EPAP, US, and Er:YAG laser significantly reduced rRNA counts (activity) on titanium and zirconium (p < .01), whereas NaOCl decreased rRNA count on titanium (p < .01). Genome count (bacterial presence) was significantly reduced by GPAP, EPAP, and US on zirconium only (p < .05). X-ray photoelectron spectroscopy analyses revealed relevant re-exposure of implant surface elements after GPAP, EPAP, and US treatment on both materials, however, not after Er:YAG laser application. Cytocompatibility was impaired by CHX, PVI, doxy, and NaOCl. CHX and PVI resulted in the lowest viability and doxy in the highest apoptosis. CONCLUSIONS: Within the limits of this in vitro study, air-polishing methods and ultrasonic device resulted in effective biofilm inactivation with surface re-exposure and favorable cytocompatibility on titanium and zirconium. Chemical agents, when applied on implant surfaces, may cause potential cytotoxic effects.

Impact of Three Nonsurgical, Full-Mouth Periodontal Treatments on Total Bacterial Load and Selected Pathobionts.

For the treatment of periodontitis stage III/IV, a quadrant/week-wise debridement (Q-SRP) was compared with three full-mouth approaches: full-mouth scaling (FMS, accelerated Q-SRP within 24 h), full-mouth scaling with chlorhexidine-based disinfection (FMD), and FMD with adjuvant erythritol air polishing (FMDAP). The objective of this prospective, randomized study (a substudy of ClinicalTrials.gov, identifier: NCT03509233) was to compare the clinical and microbiological effects of the treatments. In total, 105 patients were randomized to one of the four aforementioned treatment groups, with n = 25, 28, 27, and 25 patients allocated to each group, respectively. At baseline and 3 and 6 months after treatment, the clinical parameters, including the pocket probing depths, clinical attachment level, and bleeding on probing, were recorded, and the prevalence of the total bacteria and four periodontal pathobionts (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia) was determined using real-time quantitative PCR. Concerning the clinical outcomes, all the treatment modalities were effective, but the full-mouth approaches, especially FMDAP, were slightly superior to Q-SRP. Using the FMD approach, the reduction in the bacterial load and the number of pathobionts was significantly greater than for FMS, followed by Q-SRP. FMDAP was the least effective protocol for microbial reduction. However, after a temporary increase 3 months after therapy using FMDAP, a significant decrease in the key pathogen, P. gingivalis, was observed. These findings were not consistent with the clinical results from the FMDAP group. In conclusion, the dynamics of bacterial colonization do not necessarily correlate with clinical outcomes after full-mouth treatments for periodontitis stage III/IV.

Comparison of three full-mouth concepts for the non-surgical treatment of stage III and IV periodontitis: A randomized controlled trial.

AIM: To evaluate the clinical efficacy of full-mouth scaling (FMS), full-mouth disinfection (FMD), and FMD with adjuvant erythritol air-polishing (FMDAP) compared to quadrant-wise debridement (Q-SRP) in patients with periodontitis stage III/IV. METHODS: In this four-arm parallel, prospective, randomized, controlled multi-centre study, changes of pocket probing depths (PPDs), clinical attachment level (CAL), bleeding on probing (BOP), and proportion of closed pockets (PPD ≤4 mm without BOP) were evaluated at baseline and after 3 and 6 months. RESULTS: From 190 randomly participating patients, 172 were included in the final analysis. All groups showed significant (p < .05) improvements in all clinical parameters over 3 and 6 months. During the study period, FMDAP showed significantly higher reductions of mean PPD in teeth with moderate (PPD 4-6 mm) and deep (PPD > 6 mm) pockets and significantly increased proportions of pocket closure than Q-SRP. Patients treated with FMD had significantly greater PPD reduction in deep pockets and a higher percentage of pocket closure after 3 months but not after 6 months compared to Q-SRP. CAL and BOP changes did not significantly differ among all groups. Efficiency of treatment (time effort to gain one closed pocket) was significantly higher for FMDAP, FMD, and FMS compared to Q-SRP (6.3, 8.5, 9.5 vs. 17.8 min per closed pocket; p < .05). CONCLUSIONS: All treatment modalities were effective, without significant differences between full-mouth approaches. FMDAP showed improved clinical outcomes over Q-SRP for moderate and deep pockets after 6 months. Full-mouth protocols were more time-efficient than conventional Q-SRP. CLINICAL SIGNIFICANCE: The trial was registered in a clinical trial database (ClinicalTrials.gov: NCT03509233).

Evaluation of new endodontic tooth models in clinical education from the perspective of students and demonstrators.

BACKGROUND: The quality of root canal treatments performed by undergraduate students is often unsatisfactory questioning the current methods of teaching. Based on treatment errors made by students participating the endodontic courses at RWTH Aachen University (Germany), new radiopaque artificial root canal treatment models (DRSK RCT; incisor, premolar, molar) were designed and developed. The aim of the study was to evaluate these models by groups of students and demonstrators. METHODS: A total number of 60 students and seven demonstrators from a single institution (RWTH Aachen) participated in this study. They performed endodontic treatments on either initial versions of the DRSK RCT or modified versions. The initial versions were evaluated by students (n = 25) and demonstrators (n = 7). The obtained questionnaire was conducted as 7-point Likert-Scale covering the topics material properties, feeling while performing exercises and perception of its closeness to reality via 19 items (students) and 21 items (demonstrators). According to the evaluations several alterations were applied to the DRSK RCT, the whole study was repeated and evaluated by different students (n = 35) and the same demonstrators (n = 7). Additionally, the demonstrators blindly evaluated the quality of root canal treatments performed by the students (n = 35) on the modified DRSK RCT. Comparisons between the initial versions and the modified versions were calculated using Chi-squared tests. RESULTS: Students as well as demonstrators positively evaluated both variants of the DRSK RCT with especially high ratings in the overall evaluation. Students' rating of the pulp anatomy significantly increased from 5.4 ± 1.1 (mean ± SD) to 5.9 ± 0.9 (mean ± SD; p < 0.05) for the modified model. Likewise, students felt that the ability to flare root canals improved after alterations have been applied. Ratings significantly increased from 4.8 ± 1.6 (mean ± SD) to 5.6 ± 1.0 (mean ± SD; p < 0.05). CONCLUSION: The results indicate that the DRSK RCT is a promising candidate to be used as an alternative to extracted teeth or as an additional tool for improving dental education. However, some limitations of our analysis have to be considered.

Pilot study of a newly developed eLearning tool to teach CT and PET/CT in radiology and nuclear medicine.

AIM: To test the usability and user experience of a newly self-developed eLearning tool to teach PET/CT and CT to undergraduate medical students. METHODS: The eLearning tool permits to display PET and CT DICOM images web-based. It contains a healthy subject with anatomical annotations and a clinical case study. The usability and user experience of the eLearning tool was evaluated in undergraduate medical students of the medical faculty of the RWTH Aachen. We applied a survey based on different already existing and validated questionnaires such as System Usability Scale (SUS) and User Experience Questionnaire (UEQ-S) as well as specific questions regarding the eLearning tool. RESULTS: 38 volunteers (9 males) participated in our study. Applying the SUS resulted in a mean of 82.24, and a median of 83.75. This positive evaluation is supported by the results of the UEQ-S that were 2.2 with regard to the pragmatic quality, 2.3 with regard to hedonic quality and 2.3 for overall quality indicating a very positive evaluation. In the free-text answers, students emphasised easy and intuitive use of the eLearning tool that was additionally described as interesting and exciting. The students also positively mentioned the case study and the possibility of practice-based learning. Negative aspects were mainly problems with synchronisation of the PET and CT images. CONCLUSION: The positive evaluation is encouraging and form a foundation for further development of the eLearning module. It may be the basis for the implementation of a sustainable blended learning concept in the nuclear medicine curriculum.

O-(2-18F-fluoroethyl)-L-tyrosine PET for evaluation of brain metastasis recurrence after radiotherapy: an effectiveness and cost-effectiveness analysis.

BACKGROUND: Conventional MRI is the standard method to diagnose recurrence of brain metastases after radiation. However, following radiation therapy, reactive transient blood-brain barrier alterations with consecutive contrast enhancement can mimic brain metastasis recurrence. Recent studies have suggested that O-(2-18F-fluoroethyl)-L-tyrosine (FET) PET improves the correct differentiation of brain metastasis recurrence from radiation injury. Based on published evidence and clinical expert opinion, we analyzed effectiveness and cost-effectiveness of the use of FET PET in addition to MRI compared with MRI alone for the diagnosis of recurrent brain metastases. METHODS: A decision-tree model was designed to compare the 2 diagnostic strategies from the perspective of the German Statutory Health Insurance (SHI) system. Effectiveness was defined as correct diagnosis of recurrent brain metastasis and was compared between FET PET with MRI and MRI alone. Costs were calculated for a baseline scenario and for a more expensive scenario. Robustness of the results was tested using sensitivity analyses. RESULTS: Compared with MRI alone, FET PET in combination with MRI increases the rate of correct diagnoses by 42% (number needed to diagnose of 3) with an incremental cost-effectiveness ratio of €2821 (baseline scenario) and €4014 (more expensive scenario) per correct diagnosis. The sensitivity analyses confirmed the robustness of the results. CONCLUSIONS: The model suggests that the additional use of FET PET with conventional MRI for the diagnosis of recurrent brain metastases may be cost-effective. Integration of FET PET has the potential to avoid overtreatment with corresponding costs as well as unnecessary side effects.