Bacterial Microleakage of Cemented Orthodontic Bands

Abstract

The sealing properties of cemented orthodontic bands to bacteria was studied in this investigation. Bands were constructed for 90 mandibular incisors. A hole was made from the facial surface of the tooth, beneath the band, to the pulp chamber. The band was cemented on the tooth which was then sealed in a plastic tube with epoxy resin. The banded tooth encased within the plastic tube was sterilized in ethylene oxide gas and then inserted in a glass centrifuge tube containing sterile broth. A broth culture of Serratia marcescens was placed in the plastic tube and microleakage was determined by a reddish turbidity in the centrifuge tube. The cemented bands were tested with and without temperature cycling.

All of the cements tested exhibited varying degrees of microleakage. At the .05 level of significance, the zinc phosphate cement (thin consistency) was found to differ from zinc phosphate (standard consistency), Hydrophosphate and Silico-Phosphate cement.

Temperature cycling had a minimal effect on the thin mix of Zinc Phosphate, Zinc Oxide-Eugenol, and Silico-Phosphate cement.

All assemblies which exhibited microleakage were retested after their roots were sealed with epoxy resin. None showed growth in the centrifuge tube indicating that the path of bacterial penetration was via the opening beneath the cemented band.