A large-cohort study of 2971 cases of epulis: focusing on risk factors associated with recurrence.

BACKGROUND: To analyze the clinicopathological features of different histological subtypes of epulis, and evaluate the risk factors associated with recurrence. MATERIALS AND METHODS: A retrospective study including 2971 patients was performed. The patients' sex, age, location, size, histological subtypes, recurrence information, oral hygiene habits, periodontitis symptoms and smoking history were retrieved from the patient medical records and follow-up information. RESULTS: Among the 2971 cases, focal fibrous hyperplasia (FFH) was the most common lesion (60.92%), followed by peripheral ossifying fibroma (POF) (29.32%), pyogenic granuloma (PG) (8.08%) and peripheral giant cell granuloma (PGCG) (1.68%). The peak incidence of epulis was in the third and fourth decade of life, with a mean age of 45.55 years. Female predominance was found in all types of lesions with a female to male ratio of 1.71:1. PG had the highest recurrence rate (17.18%), followed by POF (12.98%), FFH (9.55%) and PGCG (8.82%). Histological subtypes were significantly correlated with the recurrence of epulis (P = 0.013). Regular supportive periodontal therapy (P = 0.050) had a negative correlation with recurrence, whereas symptoms of periodontitis (P < 0.001) had a positive correlation with the recurrence of epulis. CONCLUSIONS: Controlling the periodontal inflammation and regular supportive periodontal therapy might help reduce the recurrence of epulis.

A novel cone-beam CT scanning technique for measuring periodontal soft tissues in the esthetic area.

PURPOSE: This study investigated and tested a novel cone-beam computed tomography (CBCT) scanning technique capable of obtaining clear contours of soft tissues in the esthetic area. METHODS: Twenty-three periodontally healthy participants underwent this novel CBCT scanning technique. Soft tissue morphological parameters were measured on the CBCT images obtained. Intraoral clinical data were also collected at the same locations, and the accuracy of the CBCT method was tested. RESULTS: The median (interquartile range [IQR]) of the supracrestal gingival tissue thickness as 0.91 (0.73-1.13) mm, and the thickness of the central incisors was significantly greater than that of the canines (P < 0.05). The median (IQR) of keratinized tissue thickness was 0.73 (0.55-0.91) mm, which also showed a significantly greater thickness in the central incisors than in the canines (P < 0.05). Bland-Altman analysis suggested that CBCT could be accurate for measuring soft tissues in the esthetic area. CONCLUSION: The novel CBCT technique described yields clear contours of soft tissues in the esthetic area without the need for auxiliary tools. Moreover, measurements of soft tissue morphological parameters on CBCT appear to be accurate.

High expression of aryl hydrocarbon receptor (AhR) plays an important role in the formation of fibrous epulis.

OBJECTIVES: Epulis is considered to be a massive reactive lesion rather than a true neoplasia. AhR is thought to be associated with inflammation and development of neoplasms. Here, we aimed to observe the expression of AhR in fibrous epulis and explore its role and possible mechanism in the pathogenesis of epulis. MATERIALS AND METHODS: Epulis and normal gingival tissues were collected, and AhR expression was detected at the mRNA and protein levels by quantitative polymerase chain reaction (qPCR) and immunohistochemistry, respectively. The expression levels of proinflammatory cytokines and apoptosis-related factor genes in human periodontal ligament cells (hPDLCs) and human gingival fibroblasts (hGFs) transfected with AhR short interfering RNA (siRNA) or negative control siRNA, upon stimulation with lipopolysaccharide of Porphyromonas gingivalis (Pg-LPS), were then examined. Finally, the expression levels of the proinflammatory cytokines and apoptosis-related factor genes in the epulis tissues were observed by qPCR. RESULTS: AhR expression in fibrous epulis was significantly increased at both the mRNA and protein levels. The expression of proinflammatory cytokines and apoptosis-related factor genes in hPDLCs transfected with AhR siRNA was significantly decreased when stimulated with Pg-LPS. The same trends were observed for hGFs. The opposite trend was detected in the epulis tissues. CONCLUSION: AhR may be a key factor in fibrous epulis pathogenesis that acts by regulating the expression of BCL2 family genes and inflammatory factor-related genes.

Push Force Analysis of Anchor Block of the Oil and Gas Pipeline in a Single-Slope Tunnel Based on the Energy Balance Method.

In this paper, a single-slope tunnel pipeline was analysed considering the effects of vertical earth pressure, horizontal soil pressure, inner pressure, thermal expansion force and pipeline-soil friction. The concept of stagnation point for the pipeline was proposed. Considering the deformation compatibility condition of the pipeline elbow, the push force of anchor blocks of a single-slope tunnel pipeline was derived based on an energy method. Then, the theoretical formula for this force is thus generated. Using the analytical equation, the push force of the anchor block of an X80 large-diameter pipeline from the West-East Gas Transmission Project was determined. Meanwhile, to verify the results of the analytical method, and the finite element method, four categories of finite element codes were introduced to calculate the push force, including CAESARII, ANSYS, AutoPIPE and ALGOR. The results show that the analytical results agree well with the numerical results, and the maximum relative error is only 4.1%. Therefore, the results obtained with the analytical method can satisfy engineering requirements.

Influence of bone marrow-derived mesenchymal stem cells pre-implantation differentiation approach on periodontal regeneration in vivo.

AIM: The implantation of bone marrow-derived mesenchymal stem cells (MSCs) has previously been shown successful to achieve periodontal regeneration. However, the preferred pre-implantation differentiation strategy (e.g. maintenance of stemness, osteogenic or chondrogenic induction) to obtain optimal periodontal regeneration is still unknown. This in vivo study explored which differentiation approach is most suitable for periodontal regeneration. MATERIALS AND METHODS: Mesenchymal stem cells were obtained from Fischer rats and seeded onto poly(lactic-co-glycolic acid)/poly(ɛ-caprolactone) electrospun scaffolds, and then pre-cultured under different in vitro conditions: (i) retention of multilineage differentiation potential; (ii) osteogenic differentiation approach; and (iii) chondrogenic differentiation approach. Subsequently, the cell-scaffold constructs were implanted into experimental periodontal defects of Fischer rats, with empty scaffolds as controls. After 6 weeks of implantation, histomorphometrical analyses were applied to evaluate the regenerated periodontal tissues. RESULTS: The chondrogenic differentiation approach showed regeneration of alveolar bone and ligament tissues. The retention of multilineage differentiation potential supported only ligament regeneration, while the osteogenic differentiation approach boosted alveolar bone regeneration. CONCLUSION: Chondrogenic differentiation of MSCs before implantation is a useful strategy for regeneration of alveolar bone and periodontal ligament, in the currently used rat model.