Influence of CAD/CAM zirconia for implant-abutment manufacturing on gingival fibroblasts and oral keratinocytes.

OBJECTIVES: This study investigated the influence of three CAD/CAM zirconia ceramics for implant-abutment manufacturing on cell viability, migration ability, and cytotoxicity of human gingival fibroblasts (HGF) and oral keratinocytes (HOK) in vitro. MATERIALS AND METHODS: HGF and HOK were cultured on zirconia ceramic disks (VITA In-Ceram YZ, Ivoclar IPS e.max ZirCAD, Sirona inCoris ZI) and on control disks made of tissue culture polystyrene. Cell viability was analyzed by a MTT assay. Migration ability was detected by a scratch assay. A ToxiLight assay was used to analyze the influence of the tested zirconia ceramics on adenylate kinase (ADK) release and cytotoxicity. RESULTS: At MTT assay, HGF showed an increased cell viability compared to the control after 9 and 12 days for all ceramics (p each ≤0.0002) while HOK demonstrated a decreased cell viability after 9 and 12 days for all ceramics (p each ≤0.0003). At scratch assay, HGF exhibited for all ceramics decreased relative distances of the scratch wound compared to the control from 24 to 48 h (p each <0.0001) with exception of VITA In-Ceram YZ after 48 h. HOK showed increased distances compared to the control for all ceramics after 48 h (p each <0.0001). At ToxiLight assay, a minimal cytotoxicity of the tested materials could be detected. CONCLUSIONS: Overall, significant influences of the investigated CAD/CAM zirconia ceramics on HGF and HOK could be shown. CLINICAL RELEVANCE: The analyzed zirconia ceramics could influence oral soft-tissue cells that might affect the esthetic outcome after implant placement using CAD/CAM zirconia abutments.

Interdevice agreement of eight equivalent dental color measurement devices.

OBJECTIVES: The reproducibility of electronic color-measuring devices used in dentistry refers to the consistency of measurements of a single device and also that between identical devices. This in vitro study evaluated the short-term interdevice agreement of eight equivalent dental measurement devices. METHODS: The short-term repeatability of eight identical VITA Easyshade Advance color measurement devices was evaluated. Each device was used to quantify the Commission Internationale de l'Eclairage (CIE) L*a*b* color coordinates of ceramic disks, designed in accordance with guidelines set by the VITA Toothguide 3D-Master shade tab organization. Statistical analysis involved calculating the intraclass correlation coefficients (ICCs) and color differences (ΔE*) for corresponding measurements taken by the devices. In addition, the mean color difference from the mean (MCDM) was calculated for each color. RESULTS: All devices showed high ICCs for the color coordinates (L = 0.996, a = 0.993, b = 0.999). The ΔE* by shade ranged from 0.62 to 1.67. The MCDM by color-measuring device ranged from 0.11 to 0.23. CONCLUSION: This in vitro study showed that the color-measuring devices used were suitable for determining shade with high repeatability. CLINICAL RELEVANCE: The high interdevice agreement of the VITA Easyshade Advance means that dental professionals can use this device independently, without compromising the consistency and quality of color measurements.

Influence of CAD/CAM all-ceramic materials on cell viability, migration ability and adenylate kinase release of human gingival fibroblasts and oral keratinocytes.

OBJECTIVES: The aim of this study was to analyze the influence of four CAD/CAM all-ceramic materials on cell viability, migration ability and adenylate kinase (ADK) release of human gingival fibroblasts (HGF) and oral keratinocytes (HOK). MATERIALS AND METHODS: HGF and HOK were cultured on disc-shaped CAD/CAM all-ceramic materials (e.max CAD LT, e.max CAD HT, Empress CAD and Mark II) and on discs made of tissue culture polystyrene surface (TCPS) serving as control. Cell viability was analyzed by using an MTT assay, and migration ability was investigated by a scratch assay. A ToxiLight assay has been performed to analyze the effect of all-ceramic materials on ADK release and cell apoptosis. RESULTS: At MTT assay for HGF, no significant decrease of cell viability could be detected at all points of measurement (p each > 0.05), while HOK demonstrated a significant decrease in cell viability especially on Empress CAD and Mark II at each point of measurement (p each < 0.001). Scratch assay demonstrated an increased migration ability for HGF on e.max CAD HT, Empress CAD and Mark II (p each < 0.001), whereas HOK showed a significantly decreased migration ability on all tested materials at all points of measurement (between -36 % and -71 %; p each < 0.001). At ToxiLight assay, only small cytotoxic effects of the all-ceramic materials could be investigated. CONCLUSIONS: This study disclosed significant differences in cell viability and migration ability of HGF and HOK on CAD/CAM all-ceramic materials. CLINICAL RELEVANCE: CAD/CAM all-ceramic materials can influence oral cell lines responsible for soft tissue creation which may affect the esthetic outcome.

Antitumor effect of the vascular-disrupting agent ZD6126 in a murine renal cell carcinoma model.

ZD6126 is a vascular-disrupting agent that affects the endothelial tubulin cytoskeleton causing selective occlusion of tumor vasculature and extensive tumor cell necrosis. The present study evaluated the antitumor and antivascular activities of ZD6126 in the clinically relevant murine renal cell carcinoma (RENCA) model and also evaluated biological response to therapy using color Doppler imaging as biomarker. Mice were implanted with RENCA tumor cells (day 0) and established tumors were treated with ZD6126 (100 mg/kg i.p.) or vehicle with repeated intermittent doses on day 10, 14 and 18. ZD6126 treatment led to a significant reduction in tumor size and was associated with extensive tumor necrosis and a reduction in tumor blood flow versus controls. MVD increased with intermittent treatment (day 10, 14 and 18). In an additional study, animals were treated at day 19 and quantitative three-dimensional microvascular corrosion casting was performed to enable detailed assessment of the tumor vascular architecture. Corrosion casting showed that tumor vessel architecture is affected by treatment, whereas pre-existing vessels in control tissues are practically not affected. Inter-vessel and inter-branch distances as well as vessel diameters are influenced by treatment. In conclusion, ZD6126 showed potent antitumor efficacy in the RENCA model and our data suggest that decrease in tumor blood flow may be a useful surrogate marker of treatment effect.

Clinical longevity of removable partial dentures retained by telescopic crowns: outcome of the double crown with clearance fit.

PURPOSE: It was the aim of this study to investigate the long-term success of a telescopic crown system that can be used for both rigid and resilient support and to evaluate by means of a literature review whether the use of resilient support may be advantageous compared to other double crown systems when the restoration is placed on only a few remaining teeth. MATERIALS AND METHODS: Patient records were used to evaluate 125 dentures (with 460 abutment teeth) based on the Marburg double crown system. The loss of abutment teeth, endodontic treatment, and fracture of the metallic framework were investigated with regard to the different types of denture support. RESULTS: The probability that a patient would have kept all abutment teeth was 84% after 5 years and 66% after 10 years. No significant differences were found for the two groups "resilient support" (< or = three abutment teeth) and "rigid support" (> or = four abutment teeth). For abutment teeth with a double crown with clearance fit, the risk of loss was 4% after 5 years and 15% after 10 years for rigid support, and 10% and 24%, respectively, for resilient support. The risk of endodontic treatment was 7% after 5 years and 9% after 10 years for rigid support, and 3% and 7%, respectively, for resilient support. None of the denture frameworks showed a fracture during the observation period. CONCLUSION: Removable partial dentures retained by double crowns with clearance fit and constructed without major or minor connectors provide good clinical longevity. The survival rates of abutment teeth were comparable to those reported in the literature for other double crown systems. There was no significant increase of the risk of abutment loss when the restoration was placed on three or fewer remaining teeth and the concept of resilient support was applied.

A telescopic crown concept for the restoration of the partially edentulous arch: the Marburg double crown system.

PURPOSE: This article describes the concept of the Marburg double crown system (MDC system) in the treatment of partially edentulous patients. Long-term success is assessed by a review of patient records. MATERIALS AND METHODS: Double crowns with clearance fit are used to retain tooth-, mucosa-, and implant-supported removable partial dentures (RPD). To achieve retention, an additional attachment, the TC-SNAP system, is used. All metal components are fabricated in a single cobalt-chromium-molybdenum alloy; the framework (including outer crowns) is cast in one piece. Because of the framework's rigidity, the RPD can be constructed without major and minor connectors. The denture base adjacent to the abutments is fabricated using a perioprotective design that is similar to fixed partial dentures. One hundred eleven dentures, of which 49 (44%) were fabricated for patients with intraoral defects, were evaluated by reviewing patient records. RESULTS: The mean age of the patients at the time of insertion was 57.5 years (+/- 12.3). The mean number of double crowns per denture was 3.5 +/- 2.1 (range, 1 to 9). The probability that a patient will have lost all abutment teeth 10 years after insertion of the denture is 4%. The probability that a patient will have kept all teeth that abut the denture 5 years after insertion is 87%; 10 years after insertion the probability is 80%. CONCLUSION: The Marburg double crown system is a versatile and successful means of achieving the long-term restoration of the partially edentulous jaw. Insertion and removal of the denture and routine oral hygiene are easy to perform, even for patients with limited manual dexterity. As a full-arch reconstruction, the MDC system enables easy adjustment, modification, and relining with low follow-up costs.

[Changes in the physical properties of Gingivamoll flexible gingival epithesis]. / Veränderungen physikalischer Eigenschaften von Gingivaepithesen aus Gingivamoll.

It was the purpose of this study to investigate variations in weight, volume, hardness, material density, adjustment and colour of Gingivamoll flexible gingival masks during a period of twelve months. Additionally, patients were inspected for potential infections of Candida albicans. Thirty-three gingival masks of nine patients were selected for the study. One third was placed into patients' mouths, one third was placed on stone models under room conditions and a third group was submerged under water. At baseline all gingival masks were examined and measured. For the first half of the year, measurements were recorded monthly and in the second half of the year at two months' intervals. Results showed a constant Shore-A hardness, volume and density. Gingival masks submerged under water kept their weight. The other masks, i. e. those placed into patients' mouths and those placed on plaster models, lost weight. Adjustment deteriorated at distal sites. Colour stability was not satisfactory. Tests for Candida albicans remained negative. It can be concluded that Gingivamoll flexible gingival masks can be used without serious problems for a period of twelve months.

[The bonding strength of metal-enamel bonds under tensile and torsion loading]. / Verbundfestigkeit von Metall-Schmelz-Klebungen bei Zug- und Torsionsbelastungen.

The tensile strength as well as the torsion shear strength of six bonding systems were tested for the bonding of bovine enamel to Ni-Cr alloy Wiron 88 after cyclic thermal shock. The tested systems were: first sandblasting and thereafter A) silicoating and Microfill pontic, B) Microfill pontic, C) electrolytic etching and Microfill pontic, D) an experimental material which was developed of Sebond MKV, E) Estiseal/Microfill pontic, F) electrolytic etching or Estiseal/Microfill pontic BO/KII. Compared to the other methods sandblasting and silicoating (A) significantly showed the best results (p less than 0.05).

[Periodontal and caries prevention in patients with open maxillary defects following tumor surgery]. / Parodontal- und Kariesprophylaxe bei Patienten mit offenen Oberkieferdefekten nach Tumoroperation.

Patients with jaw defects resulting from tumors often have partially edentulous dentitions, because of the tumor surgery and, in most cases, advanced age. This dentition, however, can be preserved for many years and utilized in prosthodontic treatment if the principles of caries and periodontal prevention are carefully observed throughout therapy. Premature loss of teeth can only be avoided, if the prosthodontist sees the patient before surgery and before irradiation, so that the necessary measures can be taken in time.

[Relation of the activation force and deflection in various orthodontic springs (closing-loops)]. / Untersuchung über die Beziehung zwischen Aktivierungskraft und Auslenkung bei verschiedenen Zahnzugfedern (Closing-Loops).

For ten different forms of orthodontic springs, comprising three commercially available preformed types, the relationship between load (force) and the resulting deflection was determined experimentally. The experimental set-up consisted of a micrometric microscope containing a scale which could be calibrated and an optical bench so the springs could be fixed and activated by means of a force gauge in increments of 12.5 p up to 200 p. Ten springs of each of the ten forms were measured once. The results can be summarized as follows: The load-deflection rate of orthodontic springs depends on the modules of elasticity of the utilized alloy and the geometric configuration of the spring. For a given loop configuration the load-deflection rate is proportional to the modulus of elasticity. The more wire length used for shaping the spring elements (loops), the lower the load-deflection rate. With the exception of the Ladanyi retractor and the Bull loop all the springs examined showed a linear relationship between load and deflection. Because of the higher accuracy of force application and the relative force constancy during tooth movement, it is usually preferable to choose springs with a low load-deflection rate of about 50 p/mm.