A clinical evaluation of a glass ionomer cement as an orthodontic bonding adhesive compared with an acrylic resin. A comparative clinical trial of a compomer and a resin adhesive for orthodontic bonding.
Glass ionomer cement (GIC) has been suggested as an alternative to acrylic resin in bracket bonding because of its fluoride release. The aim of this clinical trial was to evaluate further the suitability of GIC as a bonding adhesive compared with an acrylic resin with regard to frequency of bracket failure, fracture modes and clean-up time after debonding. Two commercially available brackets were tested, one with a meshed foil base and the other with an integral base. A total of 60 patients, with a mean age of 13 years 7 months (range 10 years 8 months to 19 years 1 month) were consecutively selected. Brackets were bonded with a GIC (AquaCem, De Trey) and a no-mix diacrylate (Unite, Unitek Corp.) according to random assignment for each jaw. One group of patients (n = 30) was bonded with metal brackets with machine cut grooves in the base (DynaLock, Unitek). In the second group (n = 30) brackets with a meshed foil base (Unitwin, Unitek) were used. Bracket failure location during treatment was recorded as were fracture modes and time required for the clean-up of enamel surfaces at debonding. The frequency of failed brackets was higher with GIC (36 per cent) than with the diacrylate (15 per cent). Bracket failures for the cut groove base type occurred in 50 per cent with GIC and 23 per cent with the acrylic, meshed foil bases failed in 22 per cent GIC and in 7 per cent with the acrylic, respectively. The differences in failure between bracket types were significant at P < 0.001 for both bonding materials. Analysis of the fracture modes showed a small but noticeable difference in the strength of adhesion to the enamel surface, favouring GIC. Time required for the clean-up of enamel surfaces showed a significantly shorter debonding time for GIC. It is concluded that the use of a GIC for orthodontic bonding purposes considerably increases the risk of bond failures during treatment, especially in combination with a cut groove base type. One noticeable advantage with GIC bonding, however, is the shorter clean-up time for the enamel surfaces. The study aimed to compare the survival time and cariostatic potential of a compomer to that of a resin adhesive when used to bond stainless steel orthodontic brackets to labial segment teeth only. The effect of the patients' sex, age at the start of treatment and presenting malocclusion on bracket survival time was assessed also. Forty-five consecutive patients who attended for fixed appliance therapy were randomly selected. Four hundred twenty-six brackets were bonded (213 with compomer and 213 with resin adhesive) with a split mouth design; the right or left side allocation of compomer in either arch was alternated. Color transparencies of the maxillary incisors, mandibular incisors, or both, and transparencies of the canines, were taken before treatment. At the debond stage, the transparencies were projected (20x) and assessed by an experienced examiner, who used a caries index. The survival time distributions for brackets bonded with each bonding agent were not significantly different (P = .74, paired Prentice-Wilcoxon test; P = .75, Akritas test), with bracket failure rates of 17% and 20% recorded for compomer and resin adhesive, respectively. Neither the patients' sex (P = .85) nor malocclusion (P = .26) appear to affect significantly bracket survival, but patient age was identified as a useful prognostic indicator of bracket survival (P < .001). On average, there was more decalcification related to brackets bonded with resin adhesive than with compomer (P = .0075). Survival time distributions of brackets bonded with compomer or resin adhesive appear comparable, but decalcification was reduced significantly by bonding with compomer.