Dendritic cells (DCs) play a crucial role in linking innate and adaptive immunity. Thus, DCs have been regarded as a major target of immunosuppressants for the control of harmful immune responses. In this study, we examined the effect of quercetin, a natural flavonoid found in many vegetables and fruits, on the activation and function of mouse DCs. Quercetin effectively inhibited LPS-induced DC activation by reducing the production of proinflammatory cytokines/chemokines and the expression levels of MHC class II and costimulatory molecules. In addition, quercetin uniquely blocked endocytosis by DCs and the LPS-induced DC migration was diminished by quercetin treatment. Furthermore, quercetin abrogated the ability of LPS-stimulated DCs to induce Ag-specific T cell activation, both in vitro and in vivo. Remarkably, coadministration of quercetin with 2,4-dinitro-1-fluorobenzene prevented 2,4-dinitro-1-fluorobenzene–induced contact hypersensitivity, indicating the potential of quercetin for treating delayed-type hypersensitive diseases. Blockage of LPS-induced ERK, JNK, Akt, and NF-κB activation contributed to the inhibitory effect of quercetin on DCs. These results strongly suggest that quercetin may be a potent immunosuppressive agent and could be used in the prevention and therapy of chronic inflammation, autoimmunity, and transplantation via the abolishment of DC activation and function.

Background: Extraction and treatment of third molars have been cited as causing periodontal problems. To evaluate the long‐term effects of third molar extraction on the periodontal health of the mandibular second molar, a comparison of the periodontal status was performed around 2 groups of mandibular second molars, with and without third molar extraction.Methods: A total of 312 sites in 57 adult periodontitis patients were examined and the buccal and lingual locations of the mesial and distal root surfaces around the second molars were recorded. Two‐hundred and thirty‐two sites were experimental teeth; i.e., third molars had been surgically removed more than 5 years ago, 80 sites served as control molars; i.e., congenitally missing third molars. Clinical periodontal parameters including probing depth, attachment loss, and gingival recession and radiographic intrabony level were measured. The effects of the surgery and the examination (buccal or lingual) locations on the measurements were statistically analyzed.Results: Neither extraction history nor examination location affected the probing depth on mesial surfaces. However, significant effects of the surgical history on the probing depth were observed on the distal surfaces. Similar results of greater attachment loss and radiographic alveolar bone loss were observed only at the distal sites of the experimental group. In addition, the increased radiographic bone loss was only found at the distal sites (adjacent to the surgical location) and not at the mesial sites (distant from the surgical location) on the experimental group.Conclusions: In this study, greater periodontal breakdown, including probing depth, attachment loss, and radiographic alveolar bone loss, was found at the distal sites, but not at the mesial sites, of the experimental molars where the third molar was surgically extracted compared with the control teeth (no surgery). In the experimental molars, more radiographic bone loss was found at the sites adjacent to the surgical location than at the sites distant to the surgical location. Therefore, we suggest that the surgical removal of the mandibular third molar may lead to a periodontal breakdown on the distal surface of the second molar. Periodontal re‐evaluation after the initial healing of third molar extraction is indicated. J Periodontol 2001;72:1647‐1651.

Chang-Kai Chen, DDS/Da-Yo Yuh, DDS/Ren-Yeong Huang, PhD/Earl Fu, DScD/Cheng-Feng Tsai, MS/Cheng-Yang Chiang, MS: Purpose: Computer-aided surgery under navigation system guidance is widely applied in dental implant procedures. However, the accuracy of drilling with such navigation systems has not been comparatively evaluated alongside those of laboratory guide?based and freehand drilling. Therefore, this study aimed to compare the accuracies of these three drilling systems. Materials and Methods: A navigation system, a laboratory guide, and freehand drilling were used to drill 150 holes on 30 cast models. Two master models?one each for the maxilla and mandible?were prepared with the idea of placing five implants per cast. After drilling five holes on each cast, postoperative cone beam computed tomography images were acquired to measure the magnitude of errors. Results: The navigation system and laboratory guide were more accurate than freehand placement with respect to total errors at the entry and apex, lateral error at the apex, and angular error. The navigation system was more accurate than the laboratory guide with respect to angular error. Laboratory guide?based drilling was more accurate than freehand drilling in terms of lateral error at entry. Conclusion: In comparison with the laboratory guide and freehand placement, the navigation system exhibited lower angular and axial errors. Despite its higher accuracy, the navigation system requires the operator to pay greater attention.