Enamel surface after debracketing of orthodontic brackets bonded with flowable orthodontic composite. A comparison with a traditional orthodontic composite resin.

ABSTRACT

AIM: Flowable composites showed acceptable shear bond strength for bonding orthodontic brackets, but it still lacks evidence if the routine clean-up of this type of composites from enamel surface after debracketing is susceptible of more difficult procedure, due to their fluidity, and, consequently, more enamel lesions, compared with traditional orthodontic composites. Thus, this in vitro study investigated this point. METHODS: Stainless steel brackets were bonded to 60 extracted human premolars using 1) a new flowable composite (Denfil Flow) (group I; N=20); 2) a traditional flowable composite (Dyract Flow) (group II; N20); 3) Transbond XT adhesive (group III; N=20). Twenty untreated teeth were the control group. After a routine debonding procedure, the adhesive remnant index (ARI) was calculated in each tooth. After the following clean-up procedure, enamel cracks (measurements about their frequency, their position in the tooth crown and their direction) were evaluated using fiber-optic transillumination. Finally, enamel surfaces were analyzed with scanning electron microscope to quantify enamel lesions RESULTS: A significantly higher frequency of enamel cracks, (from 65% to 80%), mostly in the cervical third of tooth crown (from 65% to 80%) and vertical (from 75% to 80%), were observed in the three study groups, compared with the control group (P<0.05), without difference among the three study groups. The index of enamel lesions was significantly higher in the three study groups, compared with control group (P<0.05), without significant differences among the three study groups. CONCLUSION: Flowable composites seem to show no relevant differences in terms of enamel lesions and cracks compared with traditional composites.