Testing the Clinical Applicability of Resin Infiltration of Developmental Enamel Hypomineralization Lesions Using an In Vitro Model

Abstract

Aim: The aim of this study is to investigate the penetration abilities of a commercially available low-viscosity resin infiltrant into developmentally hypomineralized teeth in vitro.

Materials and methods: Four extracted third molars of a 17-year-old patient with signs of developmental enamel hypomineralization (discoloration, increased opacity, and surface roughness) were infiltrated with a low-viscosity resin mixed with a fluorescent dye, according to the manufacturer's standard protocol. Four extracted molars with sound enamel or showing only initial fissure caries were used as a control group. Specimens were embedded in polymethylmethacrylate, and grindings were prepared. High-resolution projectional radiography of the grindings was performed, and, for one specimen, quantitative micro-computed tomography was used to measure hydroxyapatite density in enamel and dentin lesions. After decalcification, the grindings were examined by reflected bright-field microscopy, wide-field fluorescence microscopy, and confocal laser scanning microscopy. Fluorescence micrographs were superimposed on the radiographs and analyzed correlatively.

Results: The pattern of hypo-/demineralization in enamel and dentin in developmentally hypomineralized teeth showed a good congruence with the pattern of resin infiltration. Cavitations and dentin tubules up to a depth of 2 mm beyond cavitations were filled by the infiltrant. In control teeth, the penetration of the infiltrant was limited to decalcified enamel areas (initial fissure caries).

Conclusions: In vitro infiltration of developmentally hypomineralized enamel was successful.

Clinical significance: Resin infiltration might be considered as a routine procedure in the treatment of developmentally hypomineralized teeth. Further investigations with higher sample sizes, different degrees of severity, different stages of lesion extension, and modified treatment protocols are necessary.

How to cite this article: Schnabl D, Dudasne-Orosz V, et al. Testing the Clinical Applicability of Resin Infiltration of Developmental Enamel Hypomineralization Lesions Using an In Vitro Model. Int J Clin Pediatr Dent 2019;12(2):126-132.

Keywords: Cheese molars; Developmental enamel hypomineralization; Laboratory research; Low-viscosity resin; Penetration depth; Resin infiltration.

Figs 1A to D

A 17-year-old patient's teeth with signs of developmental hypomineralization: (A) Enoral situation: yellowish teeth with white spot lesions. Oral hygiene in need of improvement; (B) Lower third molars not fully erupted. Occlusal surfaces of molars and premolars show signs of attrition; (C) Orthopantomogram: initial approximal and occlusal caries lesions in upper and lower posterior teeth; (D) Extracted test teeth (18, 28, 38, and 48) with signs of hypomineralization. Note the increased opacity, dull surface, and discoloration. The teeth were subsequently affected by caries, classified as codes 2–3 according to the International Caries Detection and Assessment System (ICDAS)

Figs 2A and B

Control tooth: (A) Radiograph shows demineralization in the outer half of enamel (E1); (B) Superimposition of radiography and fluorescence microscopy: there is a good congruence of demineralized and infiltrated areas

Figs 3A to F

Test tooth number 18: (A) Projectional radiograph shows enamel hypomineralization and caries with lesion extension into the intermediate third of dentin (D2); (B) Phantom-calibrated hydroxyapatite (HA) quantification visualizes enamel hypomineralization and carious decay; (C) Fluorescence microscopy reveals a consistent infiltration of hypomineralized enamel and also of decayed dentin; (D) Superimposition of images (A) and (C) points out congruence of patterns of hypo-/demineralization and fluorescent infiltration in enamel (E) and dentin (D); (E and F) Confocal imaging identifies the fluorescent signal within the dentin tubules penetrating far toward the pulpa

Figs 4A to D

Test tooth number 38: (A) Reflected bright-field micrograph of decalcified grinding with orange infiltrant and incomplete filling of cavitation; (B) Radiograph visualizes enamel hypomineralization and caries with lesion extension into the outer third of dentin (D1); (C) Superimposition of radiography and fluorescence microscopy shows a consistent infiltration of hypomineralized enamel and the incomplete filling of a deep fissure base (white arrow) and of an enamel/dentin cavitation (black arrow); (D) Confocal fluorescence microscopy confirms lacunas in fissure base (white arrow) and in infiltrant-filled cavitation (black arrow) and depicts a consistent infiltration of dentin around/beyond cavitation

Figs 5A to F

Test tooth number 48: (A) Radiograph of the whole ground section shows lesion extension into the outer third of dentin (D1); (B) Higher magnified radiograph; (C) Reflected bright-field micrograph of the decalcified grinding visualizes infiltration of hypomineralized enamel and carious enamel and dentin; (D) Superimposition of radiography and widefield fluorescence light microscopy images reveals a consistent infiltration of hypo-/demineralized enamel and dentin, even beyond the cavitated area; (E) Confocal fluorescence microscopy better visualizes infiltration depth; (F) Maximum intensity projection of a confocal image stack with 488 nm excitation, red and green emission filtered detection superimposed, showing (D) dentin; penetration of the infiltrant: vertical dentin tubules and delicate horizontal side channels (arrows) are filled with the fluorescent infiltrant; (E) Enamel