Some “sealants” seal—A scanning electron microscopy (SEM) investigation

• Published in: American journal of orthodontics and dentofacial orthopedics Vol. 105; no. 4; pp. 362 - 368
• Main Authors: Joseph, V.P., Rossouw, P.E., Basson, N.J.
• Format: Journal Article
• Language: English
• Published: United States Mosby, Inc 01.04.1994
• Subjects: Bisphenol A-Glycidyl Methacrylate; Dental Bonding - instrumentation; Dental Bonding - methods; Dental Cements - chemistry; Dental Enamel - ultrastructure; Dentin - ultrastructure; Dentistry; Humans; In Vitro Techniques; Microscopy, Electron, Scanning; Orthodontic Brackets - adverse effects; Pit and Fissure Sealants - chemistry; Polymethacrylic Acids; Surface Properties; Tooth Demineralization - etiology; Tooth Demineralization - prevention & control
• ISSN: 0889-5406; 1097-6752
• DOI: 10.1016/S0889-5406(94)70130-X

White spot lesions of enamel around orthodontic brackets as a result of demineralization have been well documented in the orthodontic literature. Various methods of treatment have been attempted to reduce or eliminate this danger. The purpose of this study was to evaluate, by means of scanning electron microscopy, the polymerization of the sealant layer around orthodontic brackets with direct and indirect methods of bonding. Twenty-four sound human lateral maxillary incisor teeth were collected, cleaned, divided equally into four groups A through D, and stored in 70% ethyl alcohol. Their buccal surfaces were pumiced, etched with 37% phosphoric acid for 1 minute, and washed under running water for 30 seconds. Metal brackets were bonded with the chemically cured BIS-GMA resin, Ortho Concise, as follows: group A, indirectly bonded with coping; group B, indirectly bonded without coping; and group C, directly bonded; light activated Transbond was used in group D, directly bonded brackets. After washing in alcohol for 20 seconds, all teeth were dried, and sectioned longitudinally, through the middle of the bracket. All were subjected to 5% hydrochloric acid for 30 seconds and then washed under running water for 30 seconds. After drying and sputter coating, the teeth were viewed under scanning electron microscopy. Groups A and D showed a sealant layer surrounding the brackets and covering the buccal enamel. Groups B and C showed total absence of a cured sealant layer around the brackets or surrounding enamel. It can be concluded that some bonding methods (indirect) promote sealant polymerization around the brackets (groups A and D), whereas other methods (direct) may not attain this benefit (groups B and C).