Biomedical subjects

Christine Bettina Staudt

Publications and source records attributed to Christine Bettina Staudt.

3 recordsLinked to original sources

PubMed2006

Bracket bond strength dependence on light power density.

OBJECTIVES: In order to reduce curing time for bracket bonding with light-cured composites, manufacturers increase the power density (PD) of light sources. The present study aims at investigating the relationship between PD and shear bond strength (SBS) at short exposure time. METHODS: Stainless steel brackets were bonded to bovine incisors using light-cured adhesive. Six groups of 20 incisors each were exposed to 4s of halogen light with different PD increasing from 500 to 3000 mW/cm(2) in steps of 500 mW/cm(2). Two more groups were exposed to a PD of 3000 mW/cm(2) for 6s (n=15) and 8s (n=19), thus simulating non-available PD of 4500 and 6000 mW/cm(2) for 4s. A halogen lamp with a PD of 1000 mW/cm(2) was used for 40s in the control group (n=15). After storage for 24h at 37 degrees C in water, SBS and adhesive remnant index (ARI) were recorded. RESULTS: SBS was significantly different among groups (ANOVA, p<0.001). SBS comparable to the control group could only be achieved with a PD of at least 3000 mW/cm(2). An exponential model described the relationship between SBS and PD. The best-fit curve based on this model reached 85% of the highest possible SBS at approximately 4000 mW/cm(2). ARI scores showed that higher PD was associated with better adhesion at the bracket/adhesive interface. CONCLUSIONS: Our findings show the SBS dependence on PD, and thus provide a valuable tool for the development of light-curing systems. An exponential model suggests that SBS enters a region of saturation and cannot be improved significantly by further increasing PD.

Adhesiveness↗

PubMed2005

Light-curing time reduction with a new high-power halogen lamp.

INTRODUCTION: Orthodontic brackets are routinely bonded with light-cured adhesives. Conventional halogen lights used in bonding have the disadvantage of a long curing time, and the available alternatives (laser and plasma lights) are expensive. Our aim was to investigate the minimum time necessary to bond brackets with a new, relatively low-priced, high-power halogen light. METHODS: Five groups of 15 deciduous bovine incisors were bonded with stainless steel brackets (Mini Diamond Twin, Ormco, Orange, Calif) by using different lamps and curing times. Three of the groups were bonded by using a high-power halogen light (Swiss Master Light, Electro Medical Systems, Nyon, Switzerland) for 2, 3, and 6 seconds, respectively. The fourth group, bonded with a fast halogen light (Optilux 501, Sybron Dental Specialties, Danbury, Conn) for 40 seconds, served as the positive control group. The fifth group, the comparison group, was bonded with a plasma light (Remecure, Remedent, Deurle, Belgium) for 4 seconds. After storage for 24 hours in the dark at 37 degrees C in water, shear bond strength was measured with a universal testing machine. RESULTS: A curing time of 2 seconds with the high-power halogen light negatively affected the bond strength and the probability of bond survival. The adhesive remnant index scores were not significantly different among the groups. Most failures (> 60%) occurred at the bracket base/adhesive interface. CONCLUSIONS: The high-power halogen light seems to be a cost-effective solution to reducing curing time. The recommended curing times to bond stainless steel brackets are 6 seconds and, with caution, even 3 seconds.

Analysis of Variance↗

PubMed2004

White spot lesions around brackets: in vitro detection by laser fluorescence.

Demineralization around orthodontic brackets is one of the side-effects of orthodontic treatment. However, simple methods for its early detection, quantification and monitoring are lacking. Therefore, the aim of this investigation was to evaluate red laser-light induced fluorescence for measurement of demineralization around brackets in vitro, and whether an interference by the brackets should be expected. The site of measurement was standardized on 30 extracted human molars with natural demineralization on smooth surfaces. Fluorescence was measured (Diagnodent) on prebonded, etched, bonded with stainless steel brackets, and debonded enamel. We found no statistically significant difference in fluorescence after etching. After bonding, the fluorescence decreased by a median value of 0.5 compared to the prebonded and etched enamel. After debonding, the fluorescence increased by a median value of 0.5 and 1 compared with the prebonded and bonded conditions, respectively. The lack of agreement between prebonded and bonded enamel values (limits +12.4/-12.6) was possibly due to the difficulty in finding the same spot without the bracket (coefficient of repeatability = 9.1-10.8). In vitro, demineralization around brackets can be measured by laser fluorescence, but clinical studies are necessary.

Analysis of Variance↗