Valerie Ronay

Current Status and Perspectives of Mucogingival Soft Tissue Measurement Methods

UNLABELLED The morphologic and metric assessment of mucogingival soft tissue dimensions is of great multidisciplinary clinical and academic interest, in order to quantify and monitor gingival changes while in treatment, e.g., during periodontal, restorative, prosthetic, orthodontic, or implant therapy. Pink esthetics play an increasingly important role in the overall treatment success, and therefore have to be monitored throughout therapy. The purpose of this article was to identify and summarize methods, which aim at quantifying gingival dimensions in terms of morphology, thickness, and volume, with respect to their accuracy and practicability. The introduced measurement methods should further facilitate personalized treatment planning and monitoring. CLINICAL SIGNIFICANCE Mucogingival esthetics play an increasingly important role whenever treatment results are evaluated. Several qualitative and (semi)quantitative methods for measuring soft tissue dimensions are available. New methods like CAD/CAM (computer-aided design and computer-aided manufacturing) technologies are emerging and allow practitioners to reliably monitor their patients soft tissues throughout therapy. Future improvements may help to develop better treatment strategies in terms of optimized preservation and creation of gingival morphology, especially in the esthetic zone.

In vitro cleaning potential of three different implant debridement methods

OBJECTIVES To assess the cleaning potential of three different instrumentation methods commonly used for implant surface decontamination in vitro, using a bone defect-simulating model. MATERIALS AND METHODS Dental implants were stained with indelible ink and mounted in resin models, which represented standardized peri-implantitis defects with different bone defect angulations (30, 60 and 90°). Cleaning procedures were performed by either an experienced dental hygienist or a 2nd-year postgraduate student. The treatment was repeated 20 times for each instrumentation, that is, with a Gracey curette, an ultrasonic device and an air powder abrasive device (PAD) with glycine powder. After each run, implants were removed and images were taken to detect color remnants in order to measure planimetrically the cumulative uncleaned surface area. SEM images were taken to assess micromorphologic surface changes (magnification 10,000 ×). Results were tested for statistical differences using two-way ANOVA and Bonferroni correction. RESULTS The areas of uncleaned surfaces (%, mean ± standard deviations) for curettes, ultrasonic tips, and airflow accounted for 24.1 ± 4.8%, 18.5 ± 3.8%, and 11.3 ± 5.4%, respectively. These results were statistically significantly different (P < 0.0001). The cleaning potential of the airflow device increased with wider defects. SEM evaluation displayed distinct surface alterations after instrumentation with steel tips, whereas glycine powder instrumentation had only a minute effect on the surface topography. CONCLUSION Within the limitations of the present in vitro model, airflow devices using glycine powders seem to constitute an efficient therapeutic option for the debridement of implants in peri-implantitis defects. Still, some uncleaned areas remained. In wide defects, differences between instruments are more accentuated.

Three-Dimensional Defect Evaluation of Air Polishing on Extracted Human Roots

BACKGROUND Root surfaces experience continuous abrasive instrumentation during lifelong periodontal maintenance. Periodontists need both effective and minimally abrasive debridement techniques. Air polishing devices might, therefore, constitute a good alternative to mechanical instrumentation. Because little is known of the three-dimensional shape and volume of the abrasion caused by different powders, it is the aim of the study to investigate the three-dimensional extent of these defects. METHODS Cementum-covered roots of 20 extracted human premolars were coated with resin caps, leaving four areas with identical diameter open for instrumentation using bicarbonate powder and glycine powder. Treatment times were 5 and 10 seconds in a first interval and 10 seconds in a second interval. Maximum settings were chosen for power and lavage. The teeth were scanned using microcomputed tomography initially and after every treatment interval. Differences in volume and defect depths were calculated by superimposition of the scans and tested for significance (Wilcoxon test, P <0.001). RESULTS Defect volumes (in mm(3)) presented in medians (interquartile ranges) for the bicarbonate powder after 5, 10, 15, and 20 seconds, respectively, were 0.16 (0.11), 0.28 (0.16), 0.32 (0.18), and 0.41 (0.28), and for glycine powder, 0.00 (0.02), 0.01 (0.05), 0.03 (0.11), and 0.06 (0.1). For each time period, abrasion caused by glycine was significantly lower (five- to 20-fold) compared to defects caused by bicarbonate. CONCLUSIONS In patients with exposed root surfaces, cleaning with bicarbonate powder cannot be recommended. Less abrasive glycine powder, however, demonstrated non-critical substance loss.

Expression of embryonic stem cell markers and osteogenic differentiation potential in cells derived from periodontal granulation tissue.

The aim of this study was to identify if cells obtained from periodontal granulation tissue possess embryonic stem cell properties and osteogenic capacities in vitro. Periodontal granulation tissue was removed from one furcation and one infrabony defect (FGTC/IGTC‐furcation/infrabony defect derived granulation tissue cells) of six patients. The extracted tissues were treated with collagenase/dispase solution, cultured and passaged twice, while a fraction of them was bacteriologically analyzed. Upon reaching confluence, total RNA was extracted, followed by cDNA synthesis and real‐time PCR analysis. Gene expression levels of collagen type I, alkaline phosphatase (ALP), and the embryonic stem cell markers Nanog, Oct‐4, Rex‐1 and Sox‐2 were measured, calibrated against the housekeeping gene GAPDH. Further, osteogenic differentiation was induced. Mineralized matrix formation was confirmed by von Kossa staining, and ALP activity was measured colorimetrically. The total bacterial load amounted to 9.4 ± 14.6 × 106 counts/mg of tissue for IGTC, and 11.1 ± 6.1 × 106 counts/of tissue for FGTC. Among the embryonic stem cell markers (FGTC/IGTC), Nanog was most highly expressed (3.48 ± 1.2/5.85 ± 5.7), followed by Oct‐4 (1.79 ± 0.69/2.85 ± 2.5), Sox‐2 (0.66 ± 0.3/1.26 ± 1.4) and Rex‐1 (0.06 ± 0.0/0.04 ± 0.0). The osteogenic differentiation process was positive in both FGTC and IGTC, judged by increased von Kossa staining, and elevated ALP activity and gene expression. This study provides evidence that infected periodontal granulation tissue harbors cells expressing embryonic stem cell markers, and exhibiting osteogenic capacities when in culture in vitro.

Clearance of topically-applied PVP-iodine as a solution or gel in periodontal pockets in men

Abstract Objectives. The aim of the study was to investigate the clearance of PVP-iodine applied as a gel or solution in periodontal pockets. Methods. Teeth of 12 subjects with at least eight periodontal pockets of ≥5 mm probing depth were isolated with a rubber dam to allow contamination-free access to the pockets. In each subject, three pockets were filled with PVP-iodine gel (10%) and three with PVP-iodine solution (10%). One pocket of each subject without iodine application served as a negative control. The treatment allocation was assigned randomly. Any excess material was removed subsequently. After 1, 5 and 15 min, a paper point was used to collect the sulcus liquid and the concentration of PVP-iodine was chemically determined. In addition, PVP-iodine gel was administered into 12 periodontal pockets immediately after sub-gingival ultrasound debridement and the concentration of PVP-iodine was determined after 1 min. Results. Descending concentrations of PVP-iodine were determined at 1, 5 and 15 min after the application. No PVP-iodine was found in the pockets serving as negative controls. The mean concentrations of the gel and solution were 6.14 μg/ml and 4.44 μg/ml (1 min; p ≥ 0.028), 3.20 μg/ml and 1.44 μg/ml (5 min; p ≥ 0.126), 0.69 μg/ml and 0.23 μg/ml (15 min; p ≤ 0.019), respectively. In the pockets with previous debridement the mean concentration was 1.68 ± 1.97 μg/ml. Conclusion. The application of PVP-iodine gel in periodontal pockets allows a prolonged remnant effect as compared to that of the solution formula.

In vitro evaluation of the oxidation efficacy of transgingival photodynamic therapy

Abstract Objective. To evaluate the capability of soft laser light to penetrate blood, serum, gingival connective tissue and pure collagen type I. Materials and methods. A 1:1 mixture of methylene blue (MB) and diphenylisobenzofuran (DPBF) was irradiated for 60 s with a diode laser (670 nm, 0.3 W) through blood, serum, gingival connective tissue and collagen type I (2 mm transillumination thickness). The oxidation of DPBF by MB was determined spectrophotometrically by measuring the optical density (oD) at 410 nm. The absorption spectra of DPBF/MB irradiated through MB (1%) and strawberry red solution (3%) served as control. Results. The mean oD of non-irradiated DPBF/MB was 1.98 ± 0.04. Irradiation through MB showed no oxidation of DPBF (1.98 ± 0.02; p > 0.05), while interposition of strawberry red and serum resulted in almost complete oxidation of DPBF (0.13 ± 0.09, 0.06 ± 0.03; p ≤ 0.0001). Irradiation through gingiva and collagen reduced the oxidation of DPBF significantly (1.0 ± 0.04, 0.7 ± 0.04; p ≤ 0.0001), accounting for 50% to 35% of the non-irradiated DPBF/MB solution. Conclusion. Red light from a diode laser can penetrate blood and gingival tissues. However, light absorption for collagen and connective tissue can hamper the oxidation process.