Australasian Dentist Magazine Sept-Oct 2021

Category Australasian Dentist 103 zone using 3 micro layers of A2 Tetric Evoflow (Ivoclar Vivadent) (Figure 6). The area of hypomineralization on both teeth were addressed with the next, thin A2 Dentin layer, which aimed to harmonise body value and chroma and create incisal reaching irregularities typical of internal dentin anatomy. Greater definition and correction of the halo effect value was desired and achieved using a custom mixture of Empress Color White : Ochre in a 9:1 ratio. This was delivered to the halo using a custom fissure sculpting instrument (TNTAM1, Hu-Friedy Corp, IL) (Figure 7). A degree of opalescence was desired between the incisal fingerlings, and thus applied using shade Opal Trans (Empress Direct, Ivoclar Vivadent) using an Optrasculpt instrument (Ivoclar). Of note, use of the Optrasculpt instrument obviates or minimises the clinical need to use dipping resin, which has the ability to weaken or alter the physical properties of composite if used in excessive quantities. Often, singular or multiple fine opaque connections to the dentin are seen from halo to dentin body internally. This was accomplished by using Empress Direct White and in this case is placed superficial to the cured Opal Trans layer (Figure 8). The final A1 enamel layer was sculpted in place (Empress Direct, Ivoclar Vivadent) using the Optrasculpt instrument, and primary anatomy shaped and defined (Figure 9). Secondary anatomy was mapped and sculpted using a series of needle point and thin chamfer fine diamond burs (Mani) (Figure 10) before final finishing and polishing using abrasive discs and the Optragloss two-step polishing system, which nicely highlighted the secondary and tertiary anatomy (Figure 11). Post-operative analysis indicates successful visual elimination of the areas of concern, recreation of incisal maverick and translucency features, and offers a smooth, bio-anatomical surface that should rectify any concerns the patient has relative to smiling confidence for many years to come (Figure 12). Discussion: Incisor hypomineralization is a subset of molar-incisor hypomineralization, a condition which is aesthetically and often functionally debilitating in affected individuals. It features a multifactorial etiology affecting approximately 16% of the Northern European population (Weerheijm, 2003) in low or under- fluoridated communities. The period of susceptibility is from 32 weeks in utero to 5.5 years of age and results in an enamel lesion defect that initiates from the level of the dentinoenamel junction (DEJ) and extends superficially. Fluorosis lesions in contrast are due to the presence of excessive systemic levels of fluoride and feature extension from the surface towards the DEJ. The defect of MIH or incisal hypomineralization is noted in the post-secretory stage of amelogenesis, which leaves a surface which is weak and susceptible to rapid post-eruptive breakdown from masticatory and environmental forces, increasing the risk of secondary decay. This resulting surface is defined as more irregular, porous with hydroxyapatite crystals unorganized, visually indistinct and deficient in volume. Crombie et al (2013) determined the inorganic content of affected enamel lesions as 58.8% (vol%) relative to unaffected enamel at 86%. Strategies are graded from non- invasive to progressively more invasive depending on the desires of patient and guardian if applicable. Both hydrogen and carbamide peroxide-based whitening protocols have been used successfully with or without resin infiltration strategies, the latter having widely varying success in the literature (Kumar, 2017). The patient in this case with the support of hismother decided that bothpre- prosthetic whitening and resin infiltration were to have a limited cost:benefit ratio as other teeth yet to be erupted intraorally may feature a darker chroma or value and require subsequent whitening. As there was already a deficient volume of enamel due to trauma, paired with the prominent chromatic hypomineralized lesion in 11, the decision was made to proceed with a reductive approach alone. This allows simultaneous reduction in substrate high in organic content and increases the mineral density of the resulting substrate, simultaneously providing space for corrective resin layering with a more predictable adhesive shear bond strength (Fayle, 2003). Empress Direct was chosen as a direct restorative material as it exhibits extremely tight tolerances with respect to translucency, opacity and fluorescence relative to nature. Barium glass diameters of 0.7 microns for dentin and 0.4 microns for enamel ensure clinical performance relative to strength and wear resistance as pertains to each layer. Polymerization shrinkage is controlled in the dentin layer which is often applied in a more generous application using pre-polymers, which simultaneously increase its strength. Radiopacity is boosted using ytterbium trifluoride, which also has fluoride release as an adjunct. It is a material designed to perform optically, clinically and functionally as optimally as possible using a resin composite enamel-dentin substitute and remains a gold standard in modern direct restorative armamentaria. u For a full list of references contact gapmagazines@optusnet.com.au clinical Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12