MTA-induced Notch activation enhances the proliferation of human dental pulp cells by inhibiting autophagic flux.

AIM: To determine the roles of autophagy and Notch signalling in mineral trioxide aggregate (MTA)-mediated proliferation and differentiation of human dental pulp cells (hDPCs). METHODOLOGY: hDPCs were separated from human healthy molar teeth using collagenase I/dispase II digestion and then cultured in α-MEM medium with 15% foetal bovine serum. hDPCs were seeded in 96-well plates, and cell counting kit assays were carried out to test their viability. Real-time quantitative polymerase chain reaction (qPCR) was used to evaluate ALP, Runx2, Notch1, Hes1 and Hey1 mRNA levels. Notch1, hes1, LC3 and p62 protein levels were quantified by Western blotting. Colocalization of LC3 and Notch1 was measured by immunofluorescence. Two-tailed Student's t-tests were used for statistical analysis. RESULTS: Autophagic flux was significantly (P < 0.05) inhibited by MTA extracts, causing Notch degradation arrest. This resulted in the promotion of cell proliferation and inhibition of differentiation during the logarithmic phase of cell growth. CONCLUSION: MTA extract promoted the proliferation of hDPCs in part by activating Notch signalling through inhibition of autophagic flux during the early stage and, thus, might potentially induce rapid restoration of injured pulps.

Chinese expert group consensus on diagnosis and clinical management of osteoradionecrosis of the mandible.

Osteoradionecrosis of the mandible (MORN) is one of the most devastating complications caused by radiation therapy in the head and neck region. It is characterized by infection and chronic necrosis of the mandible as the main manifestation. Clinically, MORN-related symptoms include swelling, pain, dysphagia, trismus, masticatory or speech disorders, refractory orocutaneous fistula, bone exposure, and even pathological fracture. MORN has become a challenging clinical problem for oral and maxillofacial surgeons to deal with, but thus far, this problem has not been solved due to the lack of widely accepted treatment algorithms or guidelines. Because of the nonexistence of standardized treatment criteria, most clinical treatment against MORN nowadays is largely based on controversial empirical understandings, while recommendations on post-therapeutic evaluations are scarce. Therefore, to further unify and standardize the diagnosis and treatment of MORN, to decrease the huge waste of medical resources, and ultimately, to improve the wellbeing of the patients, the Chinese Society of Oral and Maxillofacial Surgery (CSOMS) convened an expert panel specialized in MORN from 16 domestic medical colleges and affiliated hospitals to discuss the spectrum of diagnosis and and formulate treatment. In addition, consensus recommendations were also revised with a comprehensive literature review of the previous treatment experiences and research pearls. This 'expert consensus statement on diagnosis and clinical management of MORN' is for clinical reference.

An Adiponectin Receptor Agonist Reduces Type 2 Diabetic Periodontitis.

Periodontitis is twice as prevalent in diabetics as in nondiabetics, and type 2 diabetes (T2D)-associated periodontitis is severe in many cases due to the altered and aberrant functions of bone cells in hyperglycemic conditions. Therefore, developing an effective method to halt the disease process, as well as restore and regenerate lost alveolar bone to reserve the natural teeth in diabetics, is critically important. In the current study, we applied a newly discovered adiponectin receptor agonist AdipoRon (APR) in experimental periodontitis in diabetic animal models and demonstrated the underlying molecular mechanisms. We found that when APR systemically quenched the blood sugar level in diet-induced obesity (DIO) diabetic mice, it reduced osteoclast numbers and alveolar bone loss significantly due to APR's inhibition on osteoclast differentiation shown in our in vitro studies. APR also decreased the production of proinflammatory molecules CC chemokine ligand 2 and interleukin 6 in diseased gingival tissues. On the other hand, APR promoted alveolar bone regeneration through enhancing osteogenic differentiation and decreasing stromal cell-derived factor 1 in the bone marrow that facilitates stem cell migration. Same results were achieved by APR treatment of periodontitis induced in adiponectin (APN) knockout mice, indicating the ability of APR to activate the endogenous APN receptors to exert osteoanabolic effects. In summary, our study supports the notion that APR could be used as an effective multipronged approach to target T2D-associated periodontitis.

d-Alanine metabolism is essential for growth and biofilm formation of Streptococcus mutans.

Part of the d-alanine (d-Ala) metabolic pathway in bacteria involves the conversion of l-alanine to d-Ala by alanine racemase and the formation of d-alanyl-d-alanine by d-alanine-d-alanine ligase, the product of which is involved in cell wall peptidoglycan synthesis. At present, drugs that target the metabolic pathway of d-Ala are already in clinical use - e.g. d-cycloserine (DCS) is used as an antibiotic against Mycobacterium tuberculosis. Streptococcus mutans is the main cariogenic bacterium in the oral cavity. Its d-Ala metabolism-associated enzymes alanine racemase and d-alanine-d-alanine ligase are encoded by the genes smu.1834 and smu.599, respectively, which may be potential targets for inhibitors. In this study, the addition of DCS blocked the d-Ala metabolic pathway in S. mutans, leading to bacterial cell wall defects, significant inhibition of bacterial growth and biofilm formation, and reductions in extracellular polysaccharide production and bacterial adhesion. However, the exogenous addition of d-Ala could reverse the inhibitory effect of DCS. Through the means of drug regulation, our study demonstrated, for the first time, the importance of d-Ala metabolism in the survival and biofilm formation of S. mutans. If the growth of S. mutans can be specifically inhibited by designing drugs that target d-Ala metabolism, then this may serve as a potential new treatment for dental caries.

Retrospective analysis of osteoradionecrosis of the mandible: proposing a novel clinical classification and staging system.

Osteoradionecrosis of the jaw is a common radiation-induced complication that may be observed in oral cancer patients. Several classifications and staging systems have been proposed for osteoradionecrosis of the mandible based on clinical symptoms, radiological findings, and/or the response to diverse treatments. However, none has been universally accepted because of their individual deficiencies. The aim of this study was to introduce a new clinical classification that can be applied to the treatment of osteoradionecrosis in an easier and more acceptable way, through a retrospective analysis of patients with osteoradionecrosis of the mandible. A review was conducted of 99 patients diagnosed with osteoradionecrosis of the mandible in the study institution between 2000 and 2013. A novel classification was established on the basis of bone necrosis and soft tissue defects. A new staging system with four different stages (stage 0, stage I, stage II, and stage III) is proposed. We believe that this new classification and staging system is easier and more acceptable for clinical evaluation than previous ones.

Combinatorial effects of arginine and fluoride on oral bacteria.

Dental caries is closely associated with the microbial disequilibrium between acidogenic/aciduric pathogens and alkali-generating commensal residents within the dental plaque. Fluoride is a widely used anticaries agent, which promotes tooth hard-tissue remineralization and suppresses bacterial activities. Recent clinical trials have shown that oral hygiene products containing both fluoride and arginine possess a greater anticaries effect compared with those containing fluoride alone, indicating synergy between fluoride and arginine in caries management. Here, we hypothesize that arginine may augment the ecological benefit of fluoride by enriching alkali-generating bacteria in the plaque biofilm and thus synergizes with fluoride in controlling dental caries. Specifically, we assessed the combinatory effects of NaF/arginine on planktonic and biofilm cultures of Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis with checkerboard microdilution assays. The optimal NaF/arginine combinations were selected, and their combinatory effects on microbial composition were further examined in single-, dual-, and 3-species biofilm using bacterial species-specific fluorescence in situ hybridization and quantitative polymerase chain reaction. We found that arginine synergized with fluoride in suppressing acidogenic S. mutans in both planktonic and biofilm cultures. In addition, the NaF/arginine combination synergistically reduced S. mutans but enriched S. sanguinis within the multispecies biofilms. More importantly, the optimal combination of NaF/arginine maintained a "streptococcal pressure" against the potential growth of oral anaerobe P. gingivalis within the alkalized biofilm. Taken together, we conclude that the combinatory application of fluoride and arginine has a potential synergistic effect in maintaining a healthy oral microbial equilibrium and thus represents a promising ecological approach to caries management.

Treatment of cleft lip and cleft palate.

The first case of cheiloplasty recorded was in China at about 200 BC. The technique of course has been vastly improved over the centuries. Cleft lip and/or cleft palate are among the most common congenital anomalies in China and the world. There is controversy over some of the surgical techniques used and age for operation, especially in cleft palate, but the condition requires surgery. Unilateral cleft lip is operated on at 3-6 month of age and bilateral cleft lip at 6-12 month of age. Views on palatoplasty are: 1. Cleft palate should be repaired at an early age; 2. Supplementary orthodontic treatment to expand the upper arch postoperatively is necessary, and orthognathic surgery is performed if needed when the patient has matured. This is the best choice at present.

[Long-term effectiveness of arthroscopic subsynovial sclerotherapy and suturing on recurrent dislocation of the temporomandibular joint].

OBJECTIVE: To evaluate long-term effect of arthroscopic surgery on recurrent mandibular dislocation. METHODS: 30 patients with 34 involved temporomandibular joints (TMJs) (26 unilateral, 4 bilateral) were treated by arthroscopic subsynovial sclerotherapy with or without a discal traction suture. Of them, four patients with 4 TMJs were undergone repeat arthroscopic operations. In total, 38 operations were performed in 34 TMJs. After arthroscopic lysis, lavage, and manipulation, the subsynovial sclerotherapy was performed with 5% sodium morrhuate and was located at retrodiscal lamina. Suturings were taken simultaneously in 19 cases, others (n = 19) were not sutured. The total amount of 5% sodium morrhuate was from 0.4 to 1.2 ml, and the numbers of injection points were from 2 to 5, and the subsynovial depth of injection was not more than 5 mm. The follow-up was from 1 mon to 8 years. RESULTS: The total success rate was 97% (33/34). There were 21 patients with 22 involved TMJs whose follow-ups were more than 2 years. The mean follow-up was 4 years (2-8 years). The long-term success rate was 95% (21/22). There were no serious complications. CONCLUSION: The long-term effectiveness of arthroscopic sclerotherapy and suturing on recurrent mandibular dislocation is stable.

[Experimental study on the osteoradionerosis of jaw model of dogs with vascular corrosion casting].

OBJECTIVE: To study pathologic alterations of mandibular microvascular system in osteoradionecrosis of jaws (ORNJ) in order to disclose its pathologic mechanism. METHODS: The right maxillofacial regions of 10 dogs were exposed to cobalt-60 radiation with a total dose of 60-80 Gy and dental extraction were performed at 3, 6 months after radiation. The ORNJ was diagnosed by gross observation, X-ray film and histopathologic examination. Then, the vascular corrosion castings of jaws were implemented and investigated. RESULTS: At 12 months after radiation, 7 cases of ORNJ occured. It was discovered on the casting specimen that the continuity of inferior alveolar arteries remained intact except one case where the artery was obliterated due to lesion involvement. There were defects of vascular networks in the necrotic area with irregular capillaries proliferating in the periphery of lesions and around the inferior alveolar arteries, where x-ray examination showed new bone formation. CONCLUSION: Based on the experimental evidences, a new concept of pathogenesis of ORNJ is put forward: following the formation of "3-hypo" structures, local trauma-repairing process might induce capillary proliferation which bring about a large amount of mitotic death of endotheliocytes, the microcirculation failure takes place leading to ORNJ eventually.

[Experimental study of radiation effects on the mandibular microvasculature of the guinea-pigs].

In the experiment, both 180 kV X-ray and cobalt-60 radiation were delivered to right mandibles of 128 guinea-pigs with different dose (1000 cGy x 4, 800 cGy x 4, 600 cGy x 4, 400 cGy x 4 within 1 week). Dental extractions were conducted 1, 3, 5 months after radiation and the irradiated animals were examined by using microvascular corrosion castings of mandibles. It was found that the number of capillaries reduced and microvascular networks broke off after radiation with small veins shrinking subsequently while the alterations of arteries were slight. This result indicated that capillary was the most vulnerable part to the damage of radiation in the vascular system. In addition the defects of vascular networks around the non-healing tooth extraction sites were also discovered with irregularly capillary proliferation in the periphery of the lesion. The phenomena suggested that microcirculation failure induced by trauma-repairing process lead to occurRence of osteoradionecrosis of jaws.

[Arthroscopic sclerotherapy and suturing for disc displacement of the TMJ].

OBJECTIVE: The generation of the scar using TMJ arthroscopic sclerotheray in retrodiscal tissue needs some weeks. As the sclerotherapy can't fix disc reposited at once, we designed some new methods of discal traction suture with posterior sclerotherapy and anterior release. METHODS: 30 cases with 15 joints of disc displacement with reduction and 16 joints of disc displacement without reduction were treated with the above-mentioned techniques. RESULTS: The mean follow-up period was 27 mon (range 6-39). According to the rang of interincisal distances during maximum active opening and painful level using a standard 100 mm visual analog scale, and, analyzing an eight-item jaw pain questionnaire and jaw function using 5 item jaw function questionnaire, the total success rate was 74.2% (23/31), the success rate of disc displacement with reduction was 93.3% (14/15), and the success rate of disc displacement without reduction was 56.4% (9/16). CONCLUSION: TMJ arthroscopic disc traction suture with posterior sclerotherapy and anterior release is effective on disc displacement. Diagnosis, treatment and post-operative evaluation can be performed in the same arthroscopic procedure.

[The orthognathic treatment of developmental mandibular asymmetry].

OBJECTIVE: To explore the methods of orthognathic treatment for the developmental mandibular asymmetry to simultaneously achieve satisfactory facial appearance and oral functions and to prevent recurrence of the deformity. METHODS: 37 cases of developmental mandibular asymmetry have been treated in past seven years. The type of the deformity, the management of the cases, and the effects of therapy were summarized in this paper. RESULTS: According to the type of the asymmetric deformity, different means were used. After treatment, all the patients obtained satisfactory facial appearance and oral function. CONCLUSIONS: During the orthognathic treatment, it is important to simultaneously ameliorate facial appearance and achieve good oral function. It should be diagnosed before surgery whether the development of the deformity is steady or not. The correction of skeleton and soft tissues must be performed by stages.

[The changes of chewing ability after orthognathic therapy: electromyographic analysis]

OBJECTIVE:The maxillo-facial skeletal deformity can only be corrected through orthognathics that consists of orthodontics and operation.There are various changes in aspect of the bite relationship between upper and lower dentition after orthognathic surgery.The change feature of the chewing efficiency of oral maxillary system can be detected through comparing studying of the contracti on force of chewing muscles before and after surgical operation.METHODS:All 6 patients in this research were diagnosed to be skeletal crossbite.Electromyogram was used to test the change of activity of superficial masseter,temporalis and digastrics.The examination was carried out 1 week before operation and 3 months after the operation. RESULTS:When mandibular is in its rest status,there is no significant difference in the change of muscular activities.when it is active,there is significant difference. CONCLUSION:The chewing ability of masticatory muscles is reduced after orthognathic surgery.The result indicated that there is a negative bite relationship between the upper and lower dentition,the occlusion relationship needs accurate adjustment for gaining stability of oral maxillary system.Therefore,orthodontics after operation is of vital importance.

[A contour and mineral content comparison of vascularized and non-vascularized bone grafts]

This study made a comparison between vascularized bone graft (VBG) and non-vascularized bone graft (NVBG) in mandible of canine by using electron computer to assess the contour of grafted bone and measuring the mineral contents. On the 3rd, 5 th, 7 th, 15 th postoperative day, the contour of VBG and NVBG were similar and all of them kept the original contour. On the 30 th,60th,90th,180th postoperative day, VBG remained the original contour, but the contour of NVBG became thicker obviously than that of VBG for the remained cortical bone(most of which was resorbed) were enveloped with a lot of new bone. The kind of resorption of NVBG cortical bone in our study was characterized by extensive resorption on the surface just like nibbling of silkworm, unlike "tunnel" described in the literatures. There were no statistically differences between mineral contents of VBG and that of NVBG.

[The management of the treatment and diagnosis for the calcifying odontogenic cyst]

18 Patients with calcifying odontogenic cyst underwent surgery in our Department from 1977 to 1993 were reported.8 male and 10 female aged from 11 to 52 with medium or 33 years were included.16 cases were pathologically confirmed as primary intraosseous cyst(central),and 2 as extraosseous cyst(peripheral).There was no recurrence after the local excision for preripheral calcifying odontogenic cyst and local curettage for central one.There were 3 in 6 cases of tumor typed cyst who had recurred postoperatively,two of them had recurred repeatedly and cured by means of local radiotherapy.The authors recommend that the tumor type of intraosseous calcifying odontogenic cyst be classified as a border-line tumor and treated as well as the principles of low malignant tumor.Post-operative radiotherapy could be used for recurrent cases.

[A preliminary cephalometric study on characters of facial soft tissue in mandibular asymmetry cases]

OBJECTIVE: To study the alterations of facial soft tissue in mandibular asymmetry cases.METHODS:The asymmetric rates of the bone were compared with that of soft tissue by cephalometric analysis in 20 mandibular asymmetry cases by study on the thickness of the soft tissue in special position.RESULTS:It showed that the soft tissue is more symmetric than the bones.CONCLUSION:It can be concluded that the facial soft tissue is not as asymmetric as the bone.This suggests that the reconstrction of the bony deformities and the soft tissue deformities should not be performed at same time.

Evaluation of the treatment for micromandibular deformity by distraction osteogenesis with submerged intraoral device.

OBJECTIVE: To evaluate the results of distraction osteogenesis for correcting the micromandible with an intraoral device. MATERIALS AND METHODS: Eight cases of micromandible resulting from temporomandibular joint (TMJ) ankylosis and first and second branchial arch syndrome received treatment by distraction osteogenesis. Subjects included 5 females and 3 males, ranging in age from 10 to 43 years (avg 20.25). Five micromandibles were associated with obvious mandibular asymmetry. An osteotomy was performed on bilateral mandibular bodies by intraoral approach. Elongation was started on the 5th or 6th day postoperation at a rate of 0.8 to 1 mm per day. The distractors were removed after a consolidation period from 71 to 139 days. RESULTS: The distractions were fulfilled with a range of 8.5 to 24.4 mm. Pain appeared in osteotomy region when the 1 mm distraction was carried out once a day and disappeared when it was divided into twice a day. Mandibular lengthening was successful. Micromandible and facial asymmetries were corrected satisfactorily. The follow-up period ranged from a minimum of 1 month to a maximum of 10 months. There was no recurrence. One case of soft tissue infection and one case of lower lip numbness were reported. There were no cases of infection or other disturbance of wound healing or pseudarthrosis. CONCLUSIONS: Because of its advantage in little injury, avoiding bone grafting, and few complications, intraoral distraction osteogenesis is a valuable approach to correct mandibular agenesis. However, in the management of mandibular deformities, distraction osteogenesis achieves better results when combined with other orthognathic operations. How to control the direction of distraction is a problem that needs further study.

Experimental study of radiation effect on the mandibular microvasculature of the guinea pig.

OBJECTIVE: This experimental study was performed to explore the intraosseous microvascular alterations in the irradiated mandible and to increase understanding of the pathogenesis of osteoradionecrosis. METHODS: One hundred twenty-eight guinea pigs were grouped according to different radiation sources and dosages. Fractioned radiation was delivered to the right mandibles. Dental extractions were conducted at 1, 3, and 5 months respectively, after radiation. One month later, the animals were examined by means of gross observation, histopathology, and microvascular corrosion castings. RESULTS: Histologic evaluation showed bone absorption within 2 months following radiation. Four months later, the number of osteocytes decreased and pyknosis and empty lacunae were commonly seen. The casting specimens revealed under scanning electron microscopy that capillary disconnection and obliteration with subsequent vein shrinkage aggravated over time. In the nonhealing dental extraction site, a large-scale vascular network defect presented with focal capillary proliferation around. CONCLUSIONS: The capillary is the part most vulnerable to the damage caused by radiation in the vascular system of the mandible. On the basis of "hypovascular, hypoxic, hypocellular" structure, local microcirculation failure induced by the trauma-repairing process leads to occurrence of osteoradionecrosis of jaws.

[A comparison of the effects of 180kv X-ray radiation and cobalt-60 radiation on the jaws of the guinea pigs]

OBJECTIVE: Study of the effects of 180kv x-ray and cobalt-60 radiation on jaws and enhance the understanding of pathology of osteroradionecrosis of jaws(ORNJ).METHODS: 128 guinea pigs were grouped according to different irradiation sources and doses.Fractioned radiation from both sources was delivered in right mandible.The teeth extractions were conducted one week prior to radiation and 1,3,5 months after radiation respectively.Following radiation,the guinea pigs were examined by gross observation, x-ray film and histopathological examination at regular interval. RESULTS: Bone resorption occured within 1 month after irradiation as result of osteoblast inhibition and osteoclast activation.From 2 to 4 month afterwards,the number of osteocytes reduced and pyknosis, empty lacunae as well as obliteration of small vessels in periodontal membrane were commonly seen.The teeth extractions conducted at 3 months,5 months after radiation lead to ORNJ in 7 amimals (14.6%).CONCLUSION: 180kv x-ray radiation was far more damaging to jaws than cobalt-60 radiation.The dental extraction is an important factor inducint the development of ORNJ.