BackgroundAn in vitro model for peri-implantitis treatment was used to identify areas that are clinically difficult to clean by analyzing the pattern of residual stain after debridement with commonly employed instruments.MethodsOriginal data from two previous publications, which simulated surgical (SA) and non-surgical (NSA) implant debridement on two different implant systems respectively, were reanalyzed regarding the localization pattern of residual stains after instrumentation. Two blinded examiners evaluated standardized photographs of 360 initially ink-stained dental implants, which were cleaned at variable defect angulations (30, 60, or 90°), using different instrument types (Gracey curette, ultrasonic scaler or air powder abrasive device) and treatment approaches (SA or NSA). Predefined implant surface areas were graded for residual stain using scores ranging from one (stain-covered) to six (clean). Score differences between respective implant areas were tested for significance by pairwise comparisons using Wilcoxon-rank-sum-tests with a significance level α = 5%.ResultsBest scores were found at the machined surface areas (SA: 5.58 ± 0.43, NSA: 4.76 ± 1.09), followed by the tips of the threads (SA: 4.29 ± 0.44, NSA: 4.43 ± 0.61), and areas between threads (SA: 3.79 ± 0.89, NSA: 2.42 ± 1.11). Apically facing threads were most difficult to clean (SA: 1.70 ± 0.92, NSA: 2.42 ± 1.11). Here, air powder abrasives provided the best results.ConclusionMachined surfaces at the implant shoulder were well accessible and showed least amounts of residual stain. Apically facing thread surfaces constituted the area with most residual stain regardless of treatment approach.

Objective To test the accuracy of measurement of interproximal peri‐implant bone defects at titanium (Ti) and zirconium dioxide (ZrO2) implants by digital periapical radiography (PR) and cone beam computed tomography (CBCT). Material and methods A total of 18 models, each containing one Ti and one ZrO2 implant, were cast in dental stone. Six models each were allocated to following defect groups: A—no peri‐implant defect, B—1 mm width defect, C—1.5 mm width defect. The defect width was measured with a digital sliding caliper. Subsequently, the models were scanned by means of PR and CBCT. Three examiners assessed the defect width on PR and CBCT. Wilcoxon signed‐rank test and Wilcoxon rank sum test were applied to detect differences between imaging techniques and implant types. Results For PR, the deviation of the defect width measurement (mm) for groups A, B, and C amounted to 0.01 ± 0.03, −0.02 ± 0.06, and −0.00 ± 0.04 at Ti and 0.05 ± 0.02, 0.01 ± 0.03, and 0.09 ± 0.03 at ZrO2 implants. The corresponding values (mm) for CBCT reached 0.10 ± 0.11, 0.26 ± 0.05, and 0.24 ± 0.08 at Ti and 1.07 ± 0.06, 0.64 ± 0.37, and 0.54 ± 0.17 at ZrO2 implants. Except for Ti with defect A, measurements in PR were significantly more accurate in comparison to CBCT (p ≤ 0.05). Both methods generally yielded more accurate measurements for Ti than for ZrO2. Conclusions The assessment of interproximal peri‐implant defect width at Ti and ZrO2 implants was more accurate in PR in comparison to CBCT. Measurements in CBCT always led to an overestimation of the defect width, reaching clinical relevance for ZrO2 implants.

Periodontitis, an inflammatory disease, is caused by biofilms with a mixed microbial etiology and involves the progressive destruction of the tooth-supporting tissues. A rising number of studies investigate the clinical potential of photodynamic therapy (PDT) as an adjunct during active therapy. The aim of the present review was to evaluate the available literature for the in vitro antimicrobial efficacy of photodynamic therapy focusing on the periodontopathogenic bacteria Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. The focused question was: “Is it possible to decrease (at least 3 log steps or 99.9%) or even eliminate bacterial growth by photodynamic therapy in vitro when compared to untreated control groups or control groups treated by placebo?” In general, PDT resulted in a substantial reduction of surviving bacteria. However, not all studies showed the desired reduction or elimination. The ranges of log10-reduction were 0.38 (58%) to a complete eradication (100%) for P. gingivalis, 0.21 (39%) to 100% for A. actinomycetemcomitans and 0.3 (50%) to 100% for F. nucleatum. In conclusion, further and particularly more comparable studies are needed to evaluate if PDT can be clinically successful as an adjuvant in periodontal therapy.

OBJECTIVE Aim of this in vitro study was to investigate erosive tooth loss in dependence of the enamel surface structure and presence of an acquired pellicle. METHODS Enamel specimens from 19 bovine incisors (4 specimens/incisor) were allocated to four experimental groups (n = 19). The surfaces of half of the specimens were polished (two groups), while the other half was left native (two groups). Specimens of one polished and one native group were placed in pooled human saliva (30 min) for the formation of an acquired pellicle. Thereafter, all specimens were demineralized by superfusion with hydrochloric acid (17 min, pH 2.3) with collection of the superfluent. Erosive substance loss was determined by measuring the dissolved calcium content using a colorimetric assay with Arsenazo III reagent. Differences in erosive substance loss were statistically analyzed with respect to enamel surface and pellicle. A linear mixed effects model was fitted to the data and pairwise differences between groups were evaluated (significance level = 0.05). RESULTS Enamel surface structure (p < 0.001) and presence of pellicle (p = 0.01) had a significant effect on erosive substance loss. Polished surfaces with pellicle showed the lowest cumulative calcium release [nmol Ca/mm 2 ] (means ± standard deviation: 48+/-5), followed by polished specimens without (51+/-9) and native specimens with pellicle (54+/-10). No significant differences were found between these groups. Highest cumulative calcium release was found for native specimens without pellicle (61+/-9; p < 0.05). CONCLUSIONS Both enamel surface structure and the acquired pellicle are important determinants of the susceptibility to erosive tooth loss.

For some erosive beverages it can be recommended to keep the consummation temperature as low as possible to decrease the risk of erosive tooth substance loss.