STATEMENT OF PROBLEM Interim dental restorations can be fabricated by using additive manufacturing (AM) technologies. Although dental restoration contours can be easily and accurately fabricated by using computer-aided design (CAD) procedures, protocols for creating predictable color dimensions of AM interim restorations are lacking. PURPOSE The purpose of this in vitro study was to measure and compare color dimensions of different AM and conventional interim restorative materials. MATERIAL AND METHODS Disks (N=420) were fabricated by using either conventionally (CNV group) or additively manufactured (AM group) materials. The CNV group was further divided into the subgroups CNV-1 (Protemp 4; 3M ESPE) and CNV-2 (Anaxdent new outline dentin; Anaxdent). AM subgroups included AM-1 (FreePrint temp; Detax), AM-2 (E-Dent 400; Envisiontec), AM-3 (NextDent CB; NextDent), AM-4 (NextDent CB MFH; NextDent), and AM-5 (Med620 VEROGlaze; Stratasys). Color measurements in the CIELab coordinates were made by using a spectrophotometer (VITA EasyShade Advance 4.0; VITA) with a standardized photography gray card as a background under room light conditions (1003 lux). Color difference (ΔE*) values were calculated by using the CIE76 and CIEDE2000 formulas. The data were analyzed by using the Kruskal-Wallis test with nonparametric pairwise comparisons. RESULTS Owing to a software error, the spectrophotometer was unable to measure the color of any specimens in the AM-5 subgroup, which was consequently excluded from further analysis. Significant differences (P=.001) between 2 manufacturing groups were found based on the L* variable. All subgroups were significantly different from each other for all 3 variables (P<.001). Pairwise comparisons revealed that all groups were significantly different from each other, except for the AM-1 and AM-2 subgroups, compared with the CNV-1 subgroup for the L* color dimension. The ΔE* values calculated by using the CIE76 formula varied from 6.63 to 23.1 and by using the CIEDE2000 formula from 3.43 to 10.21, suggesting a perceptible and unacceptable color mismatch between the CNV and AM groups. CONCLUSIONS None of the additively manufactured interim materials tested matched the conventional interim materials in all 3 CIELab color dimensions.

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Pain can vary over the estrous cycle as a result of changes in estradiol concentration but the mechanism causing this variation is unclear. Because the thalamus is important in pain control, gene expression in the lateral thalamus (ventral posteromedial, ventral posterolateral, reticular thalamic nuclei) was screened at different phases of the estrous cycle. Gene expression changes in Sprague-Dawley rats were further analyzed by real-time PCR and ELISA and plasma estradiol levels were measured by RIAs at different phases of the estrous cycle. Our results indicated that both the RNA and protein expression of glutamate decarboxylase 1 and 2 (GAD1, GAD2), GABA(A) receptor-associated protein like 1 (GABARAPL1) and vesicular GABA transporter (VGAT) significantly increased in the lateral thalamus when plasma estradiol levels were elevated. Estradiol levels were elevated during the proestrus and estrus phases of the estrous cycle. Estrogen receptor α (ERα) was observed to be co-localized in thalamic cells and thalamic infusion of an ERα antagonist significantly reduced GAD1 and VGAT transcript. GAD1, GAD2 GABARAPL1 and VGAT have been shown to effect neuronal responses suggesting that modulation of pain during the estrous cycle can be dependent, in part, through estradiol induced changes in thalamic gene expression.

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