Dentin matrix protein 1 (DMP1) is essential to odontogenesis. Its mutations in human subjects lead to dental problems such as dental deformities, hypomineralization and periodontal impairment. Primarily, DMP1 is considered as an extracellular matrix protein that promotes hydroxyapatite formation and activates intracellular signaling pathway via interacting with avb3 integrin. Recent in vitro studies suggested that DMP1 might also act as a transcription factor. In this study, we examined whether full-length DMP1 could function as a transcription factor in the nucleus and regulate odontogenesis in vivo. We first demonstrated that a patient with the DMP1 M1V mutation, which presumably causes a loss of the secretory DMP1 but does not affect the nuclear translocation of DMP1, shows a typical rachitic tooth defect. Furthermore, we generated transgenic mice expressing NLSDMP1, in which the endoplasmic reticulum (ER) entry signal sequence of DMP1 was replaced by a nuclear localization signal (NLS) sequence, under the control of a 3.6 kb rat type I collagen promoter plus a 1.6 kb intron 1. We then crossbred the NLSDMP1 transgenic mice with Dmp1 null mice to express the NLSDMP1 in Dmp1-deficient genetic background. Although immunohistochemistry demonstrated that NLSDMP1 was localized in the nuclei of the preodontoblasts and odontoblasts, the histological, morphological and biochemical analyses showed that it failed to rescue the dental and periodontal defects as well as the delayed tooth eruption in Dmp1 null mice. These data suggest that the full-length DMP1 plays no apparent role in the nucleus during odontogenesis.

作者： 刊期： 2014年第03期

The fibrous epulis, a common tumor-like lesion of the gingiva, appears in the interdental papilla as a result of local irritation. Lesions are asymptomatic and have a variable growth rate. A 75-year-old woman was referred for the evaluation of a large painless gingival mass. It had started 10 years back and has been increasing in size the last year. No bone involvement was noted. The tumor was totally removed by excision with surgical scalpel under local anesthesia without teeth extraction. The microscopic findings were suggestive of a fibrous epulis. Differential diagnosis, clinical considerations and factors to prevent recurrence are discussed.

作者： 刊期： 2014年第03期

Spindle cell lipoma (SCL) is a benign lipomatous neoplasm typically located in the posterior neck and back of older males. It presents as a well-circumscribed mass in the buccal mucosa, tongue, floor of the mouth or hard palate. There are only two case reports of SCL in the gingiva and alveolar ridge. Here, we report a case of SCL in the mandibular mucogingival junction of a 68-year-old male. Clinical, histopathological and immunohistochemical findings are presented. Although oral SCL is rare, it should be considered in the differential diagnosis of spindle cell neoplasms occurring in the oral cavity.

作者： 刊期： 2014年第03期

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin (PA) for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin-dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2%chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.

作者： 刊期： 2014年第03期

The mucosal immune system defends against a vast array of pathogens, yet it exhibits limited responses to commensal microorganisms under healthy conditions. The oral-pharyngeal cavity, the gateway for both the gastrointestinal and respiratory tracts, is composed of complex anatomical structures and is constantly challenged by antigens from air and food. The mucosal immune system of the oral-pharyngeal cavity must prevent pathogen entry while maintaining immune homeostasis, which is achieved via a range of mechanisms that are similar or different to those utilized by the gastrointestinal immune system. In this review, we summarize the features of the mucosal immune system, focusing on T cell subsets and their functions. We also discuss our current understanding of the oral-pharyngeal mucosal immune system.

作者： 刊期： 2014年第03期

All-trans retinoic acid (ATRA) inhibits matrix metalloproteinase (MMP)-2 and MMP-9 in synovial fibroblasts, skin fibroblasts, bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells (HDPCs). The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and-9 in HDPCs. The productions and messenger RNA (mRNA) expressions of MMP-2 and-9 were accessed by gelatin zymography and real-time polymerase chain reaction (PCR), respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 mmol?L21 ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs, which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

作者： 刊期： 2014年第03期

We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First, angulation of the upper first molar varied significantly with age and tipped most distally in cases aged ,12 years and least distally in cases aged .16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.

作者： 刊期： 2014年第03期

Xerostomia is a severe side effect of radiation therapy in head and neck cancer patients. To date, no satisfactory treatment option has been established. Because mesenchymal stem cells (MSCs) have been identified as a potential treatment modality, we aimed to evaluate stem cell distribution following intravenous and intraglandular injections using a surgical model of salivary gland damage and to analyse the effects of MSC injections on the recruitment of immune cells. The submandibular gland ducts of rats were surgically ligated. Syngeneic adult MSCs were isolated, immortalised by simian virus 40 (SV40) large T antigen and characterized by flow cytometry. MSCs were injected intravenously and intraglandularly. After 1, 3 and 7 days, the organs of interest were analysed for stem cell recruitment. Inflammation was analysed by immunohistochemical staining. We were able to demonstrate that, after intravenous injection, MSCs were recruited to normal and damaged submandibular glands on days 1, 3 and 7. Unexpectedly, stem cells were recruited to ligated and non-ligated glands in a comparable manner. After intraglandular injection of MSCs into ligated glands, the presence of MSCs, leucocytes and macrophages was enhanced, compared to intravenous injection of stem cells. Our data suggest that injected MSCs were retained within the inflamed glands, could become activated and subsequently recruited leucocytes to the sites of tissue damage.

作者： 刊期： 2014年第03期