Prevalence of Distolingual Roots in the Permanent Mandibular Molars in a Chinese Population

Objective: The purpose of this study was to detect the prevalence of distolingual(DL) roots in the permanent mandibular molars in a Chinese population by using cone-beam computed tomography(CBCT).Methods : A total of 500Chinese patients'CBCT images were examined.The incidences and bilateral concurrence rates of DL roots were determined for the permanent mandibular first,second and third molars.The differences between sexes and sides were tested by using Chi-square tests.The antimeric correlations for occurrence of the trait were analyzed with the Spearman's rank order correlation test.Results : The prevalence of 3-rooted mandibular first molars was 31.98%(134 / 419individuals) calculated by individuals,and 25.89%(217 / 838teeth) calculated by teeth.The bilateral concurrence rate was 61.94%.A significant right-side predilection was found in the female group(P=0.025) as well as for both sexes combined(P=0.009).The Spearman's correlations coefficient between antimeres was 0.77(P=0.000).The prevalence of DL roots in the mandibular second and third molars were 2.02%(8 / 396individuals) and 12.10%(19 / 157individuals),respectively.The corresponding bilateral concurrence rate was 12.50% and 35.83%,and the bilateral correlation coefficient was 0.22(P=0.000) and 0.50(P=0.000),respectively.Conclusion : Clinicians should be aware of the high prevalence of the DL roots in the Chinese population.Understanding the pattern of occurrence would be useful for dental treatment.

Polydopamine functionalized mesoporous silica as ROS-sensitive drug delivery vehicles for periodontitis treatment by modulating macrophage polarization

Periodontitis is recognized as the major cause of tooth loss in adults, posing an adverse impact on systemic health. In periodontitis, excessive production of reactive oxygen species (ROS) at the inflamed site culminates in periodontal destruction. In this study, a novel ROS-responsive drug delivery system based on polydopamine (PDA) functionalized mesoporous silica nanoparticles was developed for delivering minocycline hydrochloride (MH) to treat periodontitis. The outer PDA layer and the inner MH of the nanoparticles acted as ROS scavengers and anti-inflammatory agents, respectively. Under the synergistic action of PDA and MH, macrophages were polarized from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. The in vitro experiments provided convincing evidence that PDA could scavenge ROS effectively, and the expression of pro-inflammatory cytokines was attenuated and the secretion of anti-inflammatory cytokines was enhanced through M1 to M2 polarization of macrophages with the cooperation of MH. In addition, the results obtained from the periodontitis rat models demonstrated that the synergetic effect of PDA and MH prevented alveolar bone loss without causing any adverse effect. Taken together, the results from the present investigation provide a new strategy to remodel the inflammatory microenvironment by inducing the polarization of macrophages from M1 toward M2 state for the treatment of periodontitis.