Use of micro-computed tomography and scanning electron microscopy with energy-dispersive spectroscopy to distinguish natural white spot enamel lesions from sound enamel in human premolars.

PURPOSE: The aim of the present study was to develop a novel method for distinguishing white spot lesions (WSLs) from sound enamel in human premolars using micro-computed tomography (micro-CT) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and to examine differences in surface morphology, chemical composition, and mineral density (MD) between these two areas. METHODS: Fourteen premolars with natural WSLs on the enamel surface of the crowns were examined. After sectioning the teeth, each specimen containing WSLs adjacent to intact enamel was examined for MD, surface morphology, and atomic percentages (At%) of chemical components using micro-CT and SEM/EDS, respectively. Differences between these areas of the same specimen were analyzed statistically using paired t-test. RESULTS: SEM images highlighted increased roughness and irregularity in the lesion area. EDS analysis revealed significant reductions in calcium (Ca), phosphorus (P), fluorine (F), chlorine (Cl), and sodium (Na) levels at the lesion surface in comparison to intact enamel (P < 0.05). The decreases in the MD of the lesions were statistically significant in comparison to sound enamel (P < 0.05). CONCLUSION: These findings provide standard measurements for evaluating the essential characteristics of WSLs and intact enamel, being vital for assessment of treatment outcomes and development of innovative biomaterials for management of hypo-mineralized enamel lesions.

Orthodontic management of a horizontally impacted maxillary incisor in an adolescent patient.

Horizontal maxillary incisor impaction is not common, but it affects facial esthetics, phonetics, and the patient's self-esteem. Therefore, it is necessary to manage this problem as early as possible. This case report presents a patient with an unerupted maxillary left central incisor combined with anterior and left posterior crossbite, edge-to-edge overbite on the right and left anterior open bite, low smile line, and mild skeletal Class III discrepancy. The treatment consisted of 3 stages: (1) maxillary expansion and sufficient space creation for the impacted tooth; (2) surgical exposure by closed-eruption technique; and (3) induced eruption of impaction. The treatment outcome was highly favorable. Maxillary impaction erupted in the proper position with a normal clinical crown height and consonant gingival line with the adjacent teeth. Maxillary and mandibular teeth had normal and stable occlusion. The 3-year follow-up demonstrated an esthetically functional outcome after orthodontically induced tooth eruption. This treatment required a good treatment plan by the orthodontist to obtain satisfactory results.