Australasian Dentist Magazine Sept-Oct 2021

Category 102 Australasian Dentist Background: A healthy 11 year old male presented on referral to the practice with a chief concern of unstable and irregular composite restorations affecting his maxillary central incisors. The teeth were initially described in a classic molar-incisor hypomineralization pattern with an uncavitated, brown hypomineralization lesion localized to tooth 11 and tooth 21MI status post uncomplicated enamel fracture secondary to impact with a metal drink bottle (Figure 1). The patient was described as being in a mid-mixed dentition state. Aesthetic treatment options were outlined including the possibility of pre- prosthetic whitening, which was refused by the parents after learning that further whitening procedures would need to likely be completed in the future as the remaining secondary teeth erupted intraorally, with the risk of color variance with the bleached teeth. Whitening acts to decrease the chromatic aspects of the hypomineralized lesions and simultaneously lifts the value of the background shade, decreasing the visual contrast between lesion and tooth. Resin infiltration is always an option for uncavitated hypomineralized lesions, however, with residual composite covering the teeth, structural deficits from trauma and the presence of chromatic regions within the area of organic rich hypomineraization, a conservative reduct­ ive approach was elected, both to increase the predictability of bonding in the region and to visually eliminate the lesion of interest. Treatment: Shade selection was completed prior to the application of an 18% benzocaine/2% tetracaine-based topical anesthetic (Zap, Germiphene, Brantford, ON, Canada). It is known that dehydration decreases the water content, which increases the proportionate amount of air in a tooth, decreasing the refractive index from 1.33 (water) to 1.00 (air) thereby increasing the reflective index and thus the visual value and opacity (Figure 2). Empress Direct (Ivoclar Vivadent, Schaan) composite shade buttons were selected and placed overlapping the incisal region of tooth 22, which functioned as the color reference tooth. Corresponding dentin shades were placed cervically, where the enamel was thinnest and the dentin hue most appreciable. A marked halo and sub halo translucency was noted as part of the color map. An enamel shade of A1 and a dentin shade of A2 was selected for the case (Figure 3). Following topical anaesthesia application for 90 seconds and application of 1.4 carpules of a 2% Lignocaine with 1:100,000 epinephrine solution (Septodont) via buccal infiltration, the region was isolated with a split rubber dam with clamp anchors on the upper E’s (Figure 4). The old restorative material was removed, and the hypomineralized region conservatively reduced to expose an improved amount of inorganic substrate for bonding. It was noted that there were hypomineralized regions in both the middle and incisal thirds of both 11 and 21. A partial thickness oblique fracture was noted in the enamel but did not penetrate to the palatal surface. It was decided to leave this area and reinforce it with bonded restorative material in the spirit of minimal invasion (Figure 5). The surface was isolated for a total etch adhesive approach, and the first thin lingual shelf region sculpted and defined with shade A2 Enamel with a halo of A2 Dentin (Empress Direct, Ivoclar Vivadent). This area was finessed as thin as possible in order to allow room for subsequent layers which would define the desired translucency in this zone. Resin coating was achieved in the hypomineralized Aesthetic camouflage and correction of trauma-Involved Incisor Hypomineralization Dr Clarence Tam clinical By Dr. Clarence P. Tam, HBSc, DDS, AAACD, FIADFE Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6