Clinical relevance of distolingual roots and periodontal status in mandibular first molars: a cross-sectional study employing CBCT analysis

Objectives:Distolingual root of the permanent mandibular first molar(PMFM-DLR)has been frequently reported,which may complicate the treatment of periodontitis.This study aimed to assess the morphological features of PMFM-DLR and investigate the correlation between the morphological features of PMFM-DLR and periodontal status in patients with Eastern Chinese ethnic background.Materials and methods:A total of 836 cone beam computed tomography(CBCT)images with 1497 mandibular first molars were analyzed to observe the prevalence of PMFM-DLR at the patients and tooth levels in Eastern China.Among them,complete periodontal charts were available for 69 Chinese patients with 103 teeth.Correlation and regression analyses were used to evaluate the correlation between the morphological features of DLR,bone loss,and periodontal clinical parameters,including clinical attachment loss(CAL),probing pocket depth(PPD),gingival recession(GR),and furcation involvement(FI).Results:The patient-level prevalence and tooth-level prevalence of DLR in mandibular first molars were 29.4%and 26.3%,respectively.Multiple linear regression analysis suggested that bone loss at the lingual site and CAL were negatively affected by the angle of separation between distolingual and mesial roots in the transverse section,while they were significantly influenced by age and the angle of separation between distobuccal and mesial roots in the coronal section.Conclusions:The prevalence of PMFM-DLR in Eastern China was relatively high in our cohort.The morphological features of DLR were correlated with the periodontal status of mandibular first molars.This study provides critical information on the morphological features of DLR for improved diagnosis and treatment options of mandibular molars with DLR.

Effect of 15-Deoxy-A^12,14-prostaglandin J2 Nanocapsules on Inflammation and Bone Regeneration in a Rat Bone Defect Model

Background： 15-Deoxy-^△^12、14-prostaglandin J2 （15d-PGJ2）, one of the major metabolites from prostaglandin D2 in arachidonic acid metabolic pathway, has potential anti-inflammatory properties. The objective of this study was to explore the effects of 15d-PGJ2-1oaded poly（D,L-lactide-co-glycolide） nanocapsules （15d-PGJ2-NC） on inflammatory responses and bone regeneration in local bone defect. Methods： The study was conducted on 96 Wistar rats from June 2014 to March 2016. Saline, unloaded nanoparticles, free 15d-PGJ2 or 15d-PGJ2-NC, were delivered through a collagen vehicle inside surgically created transcortical defects in rat femurs, lnterleukin-6 （IL-6）, interleukin-1 beta （IL-I~）, and tumor necrosis factor-alpha （TNF-o0 levels in the surrounding soft tissue were analyzed by Western blot and in the defect by quantitative real-time polymerase chain reaction over 14 days. Simultaneously, bone morphogenetic protein-6 （BMP-6） and platelet-derived growth factor-B （PDGF-B） messenger RNA （mRNA） in the defect were examined. New bone formation and EphrinB2 and osteoprotegerin （OPG） protein expression in the cortical defect were observed by Masson＇s Trichrome staining and immunohistochemistry over 28 days. Data were analyzed by one-way analysis of variance. Least-significant difference and Dunnett＇s T3 methods were used with a bilateral P 〈 0.05. Results： Application of 15d-PGJfNC （100μg/ml） in the local bone defect significantly decreased 1L-6, IL-Iβ, and TNF-α mRNA and protein, compared with saline-treated controls （P 〈 0.05）. 15d-PGJfNC upregulated BMP-6 and PDGF-B mRNA （P 〈 0.05）. New bone formation was observed in the cortical defect in 15d-PGJ2-NC-treated animals from 7th day onward （P 〈 0.001）. Expression of EphrinB2 and OPG presented early on day 3 and persisted through day 28 in 15d-PGJfNC group （P 〈 0.05）. Conclusion： Stable 15d-PGJz-NC complexes were prepared that could attenuate IL-6, IL-1 β, and TNF-α expression, while increasing new bone formation and growth factors related to bone regeneration.