Hans Jörg Staehle

Relationship between microtensile bond strength and nanoleakage at the composite-dentin interface

OBJECTIVES This study evaluated the relationship between microtensile bond strength (microTBS) and occurrence of nanoleakage at the resin-dentin interface using the same specimens. METHODS Resin-dentin-bonded micro-specimens (sticks with a size of 300 microm x 300 microm x 8mm) were prepared using one of two material combinations (group I: Syntac classic/Tetric Ceram Cavifil: n=57; group II: Prime & Bond NT/Spectrum TPH: n=52). After immersion of the micro-specimens in 0.1% rhodamine-B solution for 1h, nanoleakage was imaged nondestructively using a confocal laser scanning microscope (CLSM). Then the specimens were subjected to a microTBS test. RESULTS For the influence of nanoleakage on microTBS with the Syntac classic/Tetric Ceram Cavifil group, the nonparametric Spearman correlation was 0.033 at p=0.805. For the Prime & Bond NT/Spectrum TPH group, the nonparametric Spearman correlation was 0.077 at p=0.584. SIGNIFICANCE The degree of nanoleakage had no influence on microtensile bond strength for the Syntac classic/Tetric Ceram Cavifil or for the Prime & Bond NT/Spectrum TPH group.

Clinical evaluation of Helioseal F fissure sealant.

Abstract Unfilled resins are commonly in use as sealant material. In addition, there are filled sealants available. Helioseal F is a newly developed filled material with fluoride release. In this clinical trial, Helioseal F has been evaluated in one lower molar versus Delton opaque as an unfilled control in lower molars. After 12 months there were no significant differences in retention, porosities, and the number of clinically unacceptable margins between the materials. The complete retention was 30 out of 31 examined teeth for Delton and 28 out of 31 for Helioseal F. After 1 year of clinical testing, these results indicate that a sealant containing fluoride-releasing particles did not show a significant difference in retention rate compared to an unfilled conventional sealant. However, long-term results concerning marginal adaptation should be evaluated.

Effect of cavity preparation instruments (oscillating or rotating) on the composite–dentin interface in primary teeth

OBJECTIVES To evaluate the effect of preparation of instruments on the interfacial integrity between cavity wall and composite restoration. METHODS Two class II slot preparations were done in 10 primary teeth either with SonicSys or with a conventional bur. The cavities were filled using an adhesive system. One layer of a flowable composite and one layer of a condensable composite were applied. The specimens were analyzed by confocal laser scanning microscopy. RESULTS In the SonicSys group the mean thickness of the hybrid layer was 6.12 (0.60) microm; in the control group it was 6.04 (0.63) microm. The difference was not statistically significant. Two fractures were observed in one tooth of each group. These were located only in the enamel. The cavity margins were beveled in all specimens. SIGNIFICANCE Compared to conventional preparations, cavity preparation with SonicSys has no deleterious effect on the integrity of the interface.

Applications for Direct Composite Restorations in Orthodontics

Abstract.Background and Aim:Besides prosthetic and indirect, laboratory-produced restorations, the focus of dental therapy is increasingly on restorative measures and direct restorations as minimally invasive treatment concepts. Thus, the use of direct composite restorations with modern restorative materials for the shaping and recontouring of teeth in combination with orthodontic treatment offers a diversified, extensive sphere of application. The aim of the study was to demonstrate applications for direct composite restorations with reference to selected cases.Material and Methods:The composites used were hybrid composites, which offer increased abrasion resistance and color stability and are applied incrementally. Special attention was paid to the shape, color and structure of the tooth.Case Reports:The case reports present patients in whom relatively narrow or peg-shaped teeth were built up with composite to correct various tooth size discrepancies or cuspids were recontoured by means of direct composite restorations following orthodontic space closure in cases with missing lateral incisors. Similarly, space closure was achieved using orthodontically repositioned lateral incisors recontoured to resemble central incisors after traumatic loss of upper central incisors. Finally, direct composite restorations were used for retention following completion of orthodontic treatment.Conclusions:Observations over recent years confirm the stability of composites in both form and color, as well as their ability to maintain gingival health. Our case reports demonstrate that, subject to a corresponding indication, recontouring single teeth using direct composite restorations can optimize orthodontic treatment results.Zusammenfassung.Hintergrund und Ziel:Neben Zahnersatz und indirekten Laborverfahren treten zunehmend zahnerhaltende Maßnahmen und direkte Restaurationen als minimalinvasive Behandlungskonzepte in den Vordergrund der zahnärztlichen Therapie. Daher bieten der Aufbau und die Umformung von Zähnen mit den heute zur Verfügung stehenden Kompositen im Sinne einer Formkorrektur in Kombination mit kieferorthopädischen Maßnahmen ein vielfältiges und umfangreiches Einsatzgebiet. Ziel dieser Arbeit ist es, die unterschiedlichen Einsatzmöglichkeiten moderner Komposite anhand ausgewählter Behandlungsbeispiele zu veranschaulichen.Material und Methodik:Verwendet wurden Hybridkomposite, die sich durch erhöhte Abrasionsfestigkeit und Farbbeständigkeit auszeichnen und in so genannter Mehrschichttechnik aufgetragen werden. Ästhetische Aspekte bezüglich Form, Farbe sowie Struktur des Zahnes wurden in besonderem Maß berücksichtigt.Fallbeispiele:Unsere Behandlungsbeispiele zeigen Patienten, bei denen bei Zahnbreitendiskrepanzen die relativ zu schmalen Zähne aufgebaut wurden oder bei denen nach kieferorthopädischem Lückenschluss bei Nichtanlage seitlicher Schneidezähne die Eckzähne der Form der fehlenden seitlichen Schneidezähne angeglichen wurden. Ebenso konnten nach traumatischem Verlust von Frontzähnen und anschließendem kieferorthopädischen Lückenschluss die eingeordneten Zähne entsprechend der Stellung im Zahnbogen mit Komposit umgestaltet werden. Schließlich wurden Komposite auch zur Stabilisierung von Zahnstellungen und von kieferorthopädischen Behandlungsergebnissen eingesetzt.Schlussfolgerungen:Mehrjährige Fallbeobachtungen bestätigen die Beständigkeit der Komposite in Form und Farbe sowie die Stabilität der parodontalen Situation. Unsere Behandlungsbeispiele zeigen, dass sich durch die Umgestaltung einzelner Zähne mit Kompositmaterialien das kieferorthopädische Behandlungsergebnis bei entsprechender Indikation optimieren lässt.

Cyclosporine‐induced gingival overgrowth correlates with NFAT‐regulated gene expression: a pilot study

OBJECTIVE To determine whether incidence and severity of cyclosporine A (CsA)-induced gingival overgrowth (GO) is related to expression nuclear factor of activated T cells-regulated genes (NFAT-regulated genes). MATERIAL AND METHODS Expression of NFAT-regulated genes was determined in 36 transplant patients medicated with CsA by real-time PCR before and 2 h after drug intake and residual NFAT activity was estimated as ratio of both measurements. Demographic, periodontal and pharmacologic parameters were recorded and GO assessed from models. Subjects were divided into two groups according to the degree of GO (responders: GO score≥10%). Groups were compared using parametric and non-parametric tests. The association of various CsA-specific and periodontal parameters on incidence and extent of GO were determined using regression analysis. RESULTS Responders had a more than twofold lower residual NFAT activity than non-responders (7.9% and 18.1%, respectively; p<0.001). Multiple regression analysis revealed gingival inflammation, salivary CsA concentration, and residual NFAT activity to be significant factors influencing the expression of GO. Seventy-seven percent of the variability of GO could be explained by these parameters. CONCLUSIONS This study showed that pharmacodynamic parameters such as residual NFAT activity may be promising prognostic indicators to identify patients with increased risk for GO.

Localized alveolar ridge augmentation before orthodontic treatment. A case report

Extraction spaces are usually characterized by narrow, atrophic alveolar ridges, which make it difficult to move teeth orthodontically within these areas. Guided tissue regeneration is often used for alveolar ridge augmentation in implantology. In the case presented, localized alveolar ridge augmentation was performed as a preliminary procedure before orthodontic closure of an edentulous space. Guided tissue regeneration enhances the possibilities of orthodontic treatment in adult patients.

Double-blind Study on Materials Testing with Applied Kinesiology

Applied Kinesiology (AK) is a scientifically unproven method used in complementary medicine to recognize the (in)tolerance of dental materials. Test-retest reliability of AK was examined. The working hypothesis was the assumption that the reliability of AK would not exceed random chance. Two dentists qualified in AK examined 112 volunteers to determine individual (in)tolerance toward two dental composite materials. After the first examination, 31 subjects were excluded from further testing. At the end of the open test phase, 34 of 81 participants had been classified as “tolerant”, and seven as “intolerant” to both materials. The remaining 40 individuals showed a combination of either tolerant (to material I)/intolerant (to material II), or the reverse (n = 20 each). Retrieval rate was tested under blind conditions. In 14 cases, the results of the open and blinded tests matched, whereas in 26 cases they did not (95% confidence interval, 21%-52%; p = 0.98). This outcome confirmed our working hypothesis.

Three-year randomized study of manual and power toothbrush effects on pre-existing gingival recession.

Abstract Aim To compare long‐term effects of brushing with an oscillating–rotating power toothbrush or an ADA reference manual toothbrush on pre‐existing gingival recession. Materials and Methods In this controlled, prospective, single‐blind, parallel‐group study, healthy subjects with pre‐existing recession were randomized and brushed with a power toothbrush (n = 55) or an ADA reference manual toothbrush (n = 54) for a 3‐year study period. Subjects were required to brush their teeth twice daily for 2 min. using a standard fluoride toothpaste. During the study, subjects were assessed for clinical attachment loss and probing pocket depths to the nearest mm at six sites per tooth by the same calibrated examiner. Gingival recession was calculated at pre‐existing sites as the difference between clinical attachment loss and probing pocket depths. Hard and soft oral tissues were examined to assess safety. Results After 35 ± 2 months, mean gingival recession did not differ significantly between groups, but was significantly reduced from baseline (p < 0.001), from 2.35 ± 0.35 mm to 1.90 ± 0.58 mm in the power and from 2.26 ± 0.31 mm to 1.81 ± 0.66 mm in the manual group. Conclusions Gingival recession in subjects with pre‐existing recession was significantly reduced after 3 years of brushing with either a power or manual toothbrush.

Influence of Fluoridated Salt on Urinary Fluoride Excretion of Adults

After the introduction of fluoridated table salt in the staff cafeteria (VZM) of the Heidelberg University Medical and Dental School, the opportunity was taken to determine urinary fluoride excretion of those eating their main daily meals there. Subjects collected 24-hour urine in three fractions (mornings, afternoons, evenings/nights) before fluoridated table salt was introduced in the VZM, and at 6, 12 and 24 months afterwards. The fluoride concentration in the urine was determined. After 24 months, 127 of the original 200 test persons (study group) and 33 of the 60 persons in the control group could be examined. During this period, each participant in the study group took an average of 3.1 of the main meals each week at noon in the VZM. After fluoridated table salt was introduced at the VZM, fluoride excretion increased only in the afternoon urine of the test group; in this respect, the baseline examination disclosed an average of 33.98 ± 21.18 µg/h, while the follow-up examinations revealed averages of between 39.72 ± 22.58 and 42.44 ± 26.16 µg/h. This difference was statistically significant (Kruskal-Wallis test, p < 0.05). It is recommended that in studies of similar questions, fractions of urine should be collected over 24-hour periods.

Biological evaluation of subgingivally placed direct resin composite materials

Placement of composite resin restorations in deep subgingival cavities can damage surrounding soft tissues. In addition, commonly used resin-based composites (RBCs) might interfere with wound healing and periodontal health. To clarify cellular interactions with RBCs, we used an MTT assay to investigate adhesion of primary human gingival fibroblasts and human osteoblasts (hFOB 1.19) on five RBC materials with and without surface modifications (alumina blasting with 50- or 110-μm Al2O3). In addition, high-performance liquid chromatography (HPLC) was used to determine release of resin monomers from RBCs after 1 h, 1 day, and 7 days. As compared with tissue culture plastics (the control), cellular adhesion was significantly lower (P < 0.001) for human gingival fibroblasts and osteoblasts. Only minor, nonsignificant differences between individual RBCs were identified. HPLC analyses identified the release of three bifunctional methacrylates bisphenol A glycerolate dimethacrylate, triethylene glycol dimethacrylate, and diurethane dimethacrylate from RBCs and showed that monomer release increased between 1 h and 1 day but remained low. The present findings suggest that surface adhesion in the subgingival area is limited for the tested RBCs. Although residual monomer release was low for all tested RBCs, it might be sufficient to adversely affect cell adhesion.