Research Spotlight

Bai, Q., Cao, J., Dong, T. and Tao, F. (2020). “Transcriptome Analysis of Dorsal Root Ganglion in Rats with Knee Joint Inflammation.” J Pain Res 13: 2709-2720.

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BACKGROUND: Rheumatoid arthritis (RA) leads to pain through alteration of gene expression. Although gene expression alteration in knee cartilage or peripheral blood from RA patients has been identified using microarray, it remains unclear whether long non-coding RNA (lncRNA)-mediated gene regulation occurs in primary sensory neurons of dorsal root ganglia (DRG) during RA-like joint inflammation. In the present study, we aimed to analyze lncRNA and related mRNA profiles in the DRG in a knee joint inflammation rat model. METHODS: Complete Freund’s adjuvant (CFA) was injected in the rat knee joint for preparing the joint inflammation model. A lncRNA-mRNA microarray of rat DRG was employed for transcriptome analysis. Functional roles of differentially expressed lncRNAs and their related mRNAs in the injured DRG were delineated by bioinformatic analysis. RESULTS: We observed that expression levels of 9000 lncRNAs were altered on day 7 post-CFA, of which 45.17% were up-regulated and 54.83% were down-regulated. Specifically, 69 lncRNAs (42 up and 27 down) were significantly regulated. We also observed that expression levels of 13,744 mRNAs were altered on day 7 post-CFA, of which 49.67% were up-regulated and 50.33% were down-regulated. Specifically, 102 mRNAs (51 up and 51 down) were significantly regulated. Using quantitative real-time PCR, we verified the changes in differentially expressed lncRNAs in the injured DRG. CONCLUSION: These results suggest that microarray-based RNA sequencing can be used to identify altered lncRNAs and relevant mRNAs in the DRG of rats with knee joint inflammation.

Revilla-León, M., Subramanian, S.G., Att, W. and Krishnamurthy, V.R. (2020). “Analysis of Different Illuminance of the Room Lighting Condition on the Accuracy (Trueness and Precision) of An Intraoral Scanner.” J Prosthodont. Oct 23. [Epub ahead of print.].

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PURPOSE: To measure the influence of illuminance of the ambient light between 1000 lux (room light) and 10 000 lux (chair light) on the accuracy of an intraoral scanner (IOS). MATERIAL AND METHODS: A typodont was digitized using an extraoral scanner to obtain a reference standard tessellation language (STL) file. Ten groups were created based on the different illuminance of the ambient light conditions tested starting from 1000 lux (no chair light) to 10000 lux (chair light) in increments of 1000 lux by increasing the distance between the chair light and the mannequin, with the room light turned on. Ten digital scans per group were obtained (n = 10) using an IOS (Trios 3; 3Shape). The accuracy of the digital scans was evaluated with respect to the reference mesh of the typodont using a 3D mesh processing software. Kruskal-Wallis and pair-wise comparison tests were used to analyze the data (α = 0.05). RESULTS: Significant difference for trueness and precision values were found among the groups (p < 0.001). The 1000-lux group exhibited the lowest discrepancy values with a median of 26.33 μm and an interquartile range (IQR) of 40.04 μm (11.97-52.00) (p < 0.001); while the 5000-lux group obtained the highest discrepancy values with a median of 46.38 μm and an IQR of 99.94 μm (19.05-118.98) (p < 0.001). The pair-wise multi-comparison showed no difference between the 8000- and 4000-lux groups (p = 0.287). In all groups, the IQR was higher than the mean errors from the control mesh, suggesting that the relative precision was low. CONCLUSIONS: A 1000-lux illumination lighting condition is recommended to maximize the scanning accuracy of the IOS tested; the chair light should be avoided. Furthermore, the scanning accuracy response under the illuminance range tested presented a lack of monotonicity.

Piedra-Cascón, W., Meyer, M.J., Methani, M.M. and Revilla-León, M. (2020). “Accuracy (trueness and precision) of a dual-structured light facial scanner and interexaminer reliability.” J Prosthet Dent 124(5): 567-574

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STATEMENT OF PROBLEM: Digital waxing procedures should be guided by facial references to improve the esthetic outcome of a restoration. The development of facial scanners has allowed the digitalization of the extraoral soft tissues of the patient’s face. However, the reliability of facial digitizers is questionable. PURPOSE: The purpose of this study was to evaluate the accuracy (trueness and precision) of extraoral 3D facial reconstructions performed by using a dual-structured light facial scanner and to measure the interexaminer variability. MATERIAL AND METHODS: Ten participants were included. Six soft-tissue landmarks were determined on each participant, specifically reference (Ref), glabella (Gb), subnasal (Sn), menton (Me), chelion right (ChR), and chelion left (ChL). Interlandmark distances Ref-Sn, Sn-Gb, Ref-Gb, Sn-Me, and ChR-ChL (intercommissural) were measured by 2 different operators by using 2 different methods: directly on the participant’ face (manual group) and digitally (digital group) on the 3D facial reconstruction of the participant (n=20). For the manual group, interlandmark measurements were made by using digital calipers. For the digital group, 10 three-dimensional facial reconstructions were acquired for each participant by using a dual-structured light facial scanner (Face Camera Pro Bellus; Bellus3D). Interlandmark measurements were made by using an open-source software program (Meshlab; Meshlab). Both operators were used to note 10 measurements for each manual and digital interlandmark distance per participant. The intraclass correlation coefficient between the 2 operators was calculated. The Shapiro-Wilk test revealed that the data were not normally distributed. The data were analyzed by using the Mann-Whitney U test. RESULTS: Significant differences were found between manual and digital interlandmark measurements in all participants. The mean value of the manual and digital group discrepancy was 0.91 ±0.32 mm. The dual-structured light facial scanner tested obtained a trueness mean value of 0.91 mm and a precision mean value of 0.32 mm. Trueness values were always higher than precision mean values, indicating that precision was relatively high. The intraclass correlation coefficient between the 2 operators was 0.99. CONCLUSIONS: The facial digitizing procedure evaluated produced clinically acceptable outcomes for virtual treatment planning. The interexaminer reliability between the 2 operators was rated as excellent, suggesting that the type of facial landmark used in this study provides reproducible results among different examiners.

Azarpazhooh, A., Diogenes, A.R., Fouad, A.F., Glickman, G.N., Kishen, A., Levin, L., Roda, R.S., Sedgley, C.M., Tay, F.R. and Hargreaves, K.M. (2020). “Insights into the November 2020 issue of the JOE.” J Endod 46(11): 1537-1538.

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Welcome to the November 2020 issue of the JOE. Here, we share some of our favorite articles that are published in this issue of the Journal. We hope you look forward to reading these and other articles in the JOE. [No abstract; excerpt from Editorial.].

Ma, C., Jing, Y., Li, H., Wang, K., Wang, Z., Xu, C., Sun, X., Kaji, D., Han, X., Huang, A. and Feng, J. (2020). “Scx(Lin) cells directly form a subset of chondrocytes in temporomandibular joint that are sharply increased in Dmp1-null mice.” Bone 142: 115687.

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It has been assumed that the secondary cartilage in the temporomandibular joint (TMJ), which is the most complex and mystery joint and expands rapidly after birth, is formed by periochondrium-derived chondrocytes. The TMJ condyle has rich attachment sites of tendon, which is thought to be solely responsible for joint movement with a distinct cell lineage. Here, we used a Scx-Cre ERT2 mouse line (the tracing line for progenitor and mature tendon cells) to track the fate of tendon cells during TMJ postnatal growth. Our data showed a progressive differentiation of Scx lineage cells started at tendon and the fibrous layer, to cells at the prechondroblasts (Sox9 -/Col I +), and then to cells at the chondrocytic layer (Sox9 +/Col I -). Importantly, the Scx + chondrocytes remained as “permanent” chondrocytes to maintain cartilage mass with no further cell trandifferentiation to bone cells. This notion was substantiated in an assessment of these cells in Dmp1 -null mice (a hypophosphatemic rickets model), where there was a significant increase in the number of Scx lineage cells in response to hypophosphatemia. In addition, we showed the origin of disc, which is derived from Scx + cells. Thus, we propose Scx lineage cells play an important role in TMJ postnatal growth by forming the disc and a new subset of Scx + chondrocytes that do not undergo osteogenesis as the Scx – chondrocytes and are sensitive to the level of phosphorous.