[Analyzing the relevant factors affecting the clinical outcome of periodontal regeneration surgery].

Periodontitis can lead to periodontal tissue defect, tooth mobility and loss, which seriously affects the quality of life. Periodontal regeneration surgery is an important treatment method for repairing periodontal defects, and it is also the hotspot of current periodontal clinical and basic research. A comprehensive understanding of the factors affecting the efficacy of periodontal regenerative surgery can improve clinicians' periodontal treatment concepts, increases the predictability of treatment results, and enhances the level of clinical diagnosis and periodontal treatment. In order to instruct the clinicians, this article will explain the basic principles of periodontal regeneration and the key points of periodontal wound healing, and analyze the elements of periodontal regeneration surgery, which including the patient-related factors, local factors, surgical factors and regenerative material selection.

[Association between periodontitis and mild cognitive impairment: a clinical pilot study].

Objective: To evaluate the association between periodontitis and mild cognitive impairment (MCI), and explore the potential local oral risk factors for MCI. Methods: The study included 70 middle-aged and elderly subjects (44 females and 26 males) with periodontal disease who were first diagnosed by the Department of Periodontology or referred by the Department of Geriatrics in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from January 2021 to January 2022. In this study, the control group consisted of periodontal disease patients without cognitive impairment, and the case group (MCI group) consisted of those diagnosed with MCI referred by the geriatrics specialists. Full-mouth periodontal examinations of all subjects were performed and periodontal indicators were recorded by periodontists, while digital panoramic radiographs were taken. The severity of periodontitis was defined according to the 1999 classification, and the staging and grading of periodontitis were defined according to the 2018 American Academy of Periodontology and European Federation of Periodontology classification. The mini-mental state examination scale was chosen by geriatricians to evaluate the cognitive function of the included subjects. The cubital venous blood was drawn to detect the expression levels of inflammatory factors such as hypersensitive C-reactive protein (hs-CRP), interleukin (IL)-1ß, IL-6 and tumor necrosis factor-α(TNF-α) in serum. Independent-samples t test and chi-square test were used to analyze the differences in population factors, periodontal-related indexes and serum inflammatory factors between the two groups (α=0.05). Odds ratios (OR) for MCI according to the severity of periodontitis and main periodontal clinical indexes were calculated by binary Logistic analysis. Results: Thirty-nine subjects were included in the control group and thirty-one in the MCI group. The age of the study population was (58.3±6.2) years (range: 45-70 years). The comparison between two groups showed that the control group was with higher educational background (χ²=9.45, P=0.024) and 2.6 years younger than the MCI group [(57.1±6.0) years vs. (59.7±6.3) years, t=-1.24, P=0.082]. The number and proportion of moderate to severe periodontitis in control group were significantly lower compared to those in MCI group (17 cases with 43.6% vs. 23 cases with 74.2%, χ²=6.61, P=0.010), and the OR of moderate to severe periodontitis adjusted by age and educational background was 3.00 (95%CI: 1.01-8.86, P=0.048). Compared with the grading (χ²=5.56, P=0.062) of periodontitis, staging had a greater impact on MCI (χ²=7.69, P=0.041), moreover the proportion of MCI in stage Ⅰ grade A periodontitis was significantly lower than any other type of periodontitis (χ²=13.86, P=0.036). In addition, less presence of deep periodontal pockets [probing depth (PD)≥6 mm] (17.9% vs. 41.9%, χ²=4.87, P=0.027), fewer number of PD≥4 mm (6.48±6.70 vs. 11.03±8.91, t=-2.44, P=0.017), lower plaque index (1.42±0.56 vs. 1.68±0.57, t=-1.91, P=0.059) and gingival index (1.68±0.29 vs. 1.96±0.30, t=-3.93, P<0.001) were in the control group than in the MCI group. However, there were no significant differences between the two groups in the levels of serum inflammatory factors, such as hs-CRP, IL-1ß, IL-6 and TNF-α (P>0.05). Conclusions: It appears a strong correlation between moderate to severe periodontitis and the incidence of MCI in middle-aged and elderly people. Moreover, deep and increased number of periodontal pockets, poor oral hygiene, and severe gingival inflammation can be potentially associated risk factors for MCI.

[Periodontally accelerated osteogenic orthodontics in clinical treatment].

Orthodontic tooth movement inevitably affects adjacent periodontal tissue. The labiobuccal alveolar bone is generally thin, and patients with dental crowding often present alveolar dehiscence and fenestration. These may lead to prolonged treatment time, even gingival atrophy, tooth loosening and other complications in the orthodontic tooth movement. Periodontally accelerated osteogenic orthodontics (PAOO) could accelerate the orthodontic tooth movement and promote the formation of new bone by using corticotomy and bone grafting. This article, starting from the influence of orthodontic treatment on periodontal hard tissue, describes the application of PAOO in orthodontic treatment.

Initial comparison of proteomic profiles of whole unstimulated saliva obtained from generalized aggressive periodontitis patients and healthy control subjects.

BACKGROUND AND OBJECTIVE: Salivary proteomics technology can be used to evaluate the disease progression of periodontitis and the systemic screening of proteomes of saliva from subjects with aggressive periodontitis has not been available. The objective of this preliminary study was to compare the proteomic profile of whole unstimulated saliva of subjects with generalized aggressive periodontitis (GAgP) with that of healthy volunteers to identify proteins, the levels of which were significantly altered between the two groups. MATERIAL AND METHODS: Whole unstimulated saliva was obtained from five subjects with GAgP and five healthy subjects, and proteins were separated using two-dimensional gel electrophoresis. Proteins, the levels of which were significantly different between the two groups, were identified by computer image analyses and subsequent electrospray ionization tandem mass spectrometry. RESULTS: Eleven proteins that exhibited a different level in the GAgP group vs. the control group were identified. Compared with whole saliva of healthy control subjects, the levels of serum albumin, immunoglobulin (Ig) gamma2 chain C region, Ig alpha2 chain C region, vitamin D-binding protein, salivary alpha-amylase and zinc-alpha2 glycoprotein were increased in whole unstimulated saliva of GAgP subjects, while those of lactotransferrin, elongation factor 2, 14-3-3 sigma, short palate, lung and nasal epithelium carcinoma-associated protein 2 precursor and carbonic anhydrase 6 were decreased. CONCLUSION: Comparison of the proteomic profile of whole unstimulated saliva of GAgP subjects with that of healthy control subjects revealed at least 11 differential proteins. The approach applied herein might be helpful to aid understanding of the etiology of GAgP.

[Expression profile of long non-coding RNA in gingival tissues from the patients with aggressive periodontitis].

Objective: To detect and analyze the differential expression profile of long non-coding RNA (lncRNA) in aggressive periodontitis (AgP) and healthy gingival tissues, in order to explore the role of lncRNA in AgP. Methods: After the informed consents were obtained, gingival tissues from AgP patients (n=40) and healthy volunteers (n=40) were collected in Department of Periodontology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine (from Mar. 2012 to Aug. 2012) and Department of Periodontology, Hospital of Stomatology, Tianjin Medical University (from Oct. 2016 to Apr. 2017). The differential expression of lncRNA of tissues from AgP patients (n=20) and healthy volunteers (n=20) were examined via microarray assay. Bioinformatics was applied to analyze the expression data of lncRNA and correlative mRNA. Two lncRNAs (lncRNA-TNFRSF13C and lncRNA-API5) were chosen to verify the microarray results by using real time quantitative polymerase chain reaction (PCR) in the other gingival tissues. Results: Compared with the result of healthy gingival tissues, totally 8 632 lncRNAs were differentially expressed in tissues from AgP patients. From these data, 1 986 lncRNAs were significantly upregulated while 6 646 lncRNAs were downregulated, amongst which 48 lncRNAs were upregulated (>10 times) (P<0.05), 14 lncRNAs were downregulated (>10 times) (P<0.05). Furthermore, totally 5 519 correlative mRNAs were differentially expressed, amongst which 1 676 mRNAs were upregulated (≥2 times, P<0.05) and 3 843 mRNAs were downregulated≤0.5 (P<0.05). The selected lncRNA-TNFRSF13C and lncRNA-API5 were up-regulated in AgP (P<0.05), which confirmed the results of microarray. From bioinformatics, differential expression lncRNAs were in association with many signal pathways including toll-like receptor signaling pathway, cell cycle and apoptosis pathway, and tumor necrosis factor receptor superfamily pathway. Conclusions: LncRNA may be involved in the pathogenesis of AgP through various pathways, which need to be further explored.

A study of enamel matrix proteins on differentiation of porcine bone marrow stromal cells into cementoblasts.

OBJECTIVE: To further explore the role of enamel matrix proteins (EMPs) in periodontal regeneration, we have used porcine bone marrow-derived stromal cells (BMSCs) to observe whether the EMPs could have an effect on their differentiation into cementoblasts. MATERIALS AND METHODS: In this study, EMPs were extracted from porcine tooth germs by the use of acetic acid. BMSCs obtained from porcine iliac marrow aspiration were inoculated onto the surface of autologous root slices treated with or without EMPs. Following 7-day co-culture, all the BMSC-seeded root slices, with their respective non-cell-inoculated control specimens, were pocketed with expanded polytetrafluoroethylene membrane and were transplanted subcutaneously into 11 nude mice. The animals were sacrificed after 3 and 8 weeks, and the new specimens were processed for haematoxylin and eosin staining. RESULTS: Histological analysis demonstrated new cellular cementum-like tissue formed along EMP-treated root slices. CONCLUSION: Our work has indicated for the first time, differentiation of BMSCs into cementoblasts using an EMP-based protocol.

Central sensitization in thalamic nociceptive neurons induced by mustard oil application to rat molar tooth pulp.

We have recently demonstrated that application of mustard oil (MO), a small-fiber excitant and inflammatory irritant, to the rat maxillary molar tooth pulp induces central sensitization that is reflected in changes in spontaneous activity, mechanoreceptive field (RF) size, mechanical activation threshold, and responses to graded mechanical stimuli applied to the neuronal RF in trigeminal brainstem subnucleus caudalis and subnucleus oralis. The aim of this study was to test whether central sensitization can be induced in nociceptive neurons of the posterior thalamus by MO application to the pulp. Single unit neuronal activity was recorded in the ventroposterior medial nucleus (VPM) or posterior nuclear group (PO) of the thalamus in anesthetized rats, and nociceptive neurons were classified as wide dynamic range (WDR) or nociceptive-specific (NS). MO application to the pulp was studied in 47 thalamic nociceptive neurons and found to excite over 50% of the 35 VPM neurons tested and to produce significant long-lasting (over 40 min) increases in spontaneous activity, cutaneous pinch RF size and responses to graded mechanical stimuli, and a decrease in threshold in the 29 NS neurons tested; a smaller but statistically significant increase in mean spontaneous firing rate and decrease in activation threshold occurred following MO in the six WDR neurons tested. Vehicle application to the pulp did not produce any significant changes in six VPM NS neurons tested. MO application to the pulp produced pronounced increases in spontaneous activity, pinch RF size, and responses to mechanical stimuli, and a decrease in threshold in three of the six PO neurons. In conclusion, application of the inflammatory irritant MO to the tooth pulp results in central sensitization of thalamic nociceptive neurons and this neuronal hyperexcitability likely contributes to the behavioral consequences of peripheral inflammation manifesting as pain referral, hyperalgesia and allodynia.

Central α-adrenoceptors contribute to mustard oil-induced central sensitization in the rat medullary dorsal horn.

Our previous studies have demonstrated that application of the inflammatory irritant mustard oil (MO) to the tooth pulp produces trigeminal central sensitization that includes increases in mechanoreceptive field size and responses to noxious stimuli and decrease in activation threshold in brainstem nociceptive neurons of trigeminal subnucleus caudalis (the medullary dorsal horn, MDH). The aim of the present study was to test if central noradrenergic processes are involved in the central sensitization of MDH neurons and if α1-adrenoceptors or α2-adrenoceptors or both are involved. In urethane/α-chloralose-anesthetized rats, the activity of extracellularly recorded and functionally identified single nociceptive neurons in the MDH was studied. Continuous intrathecal (i.t.) superfusion of the adrenergic modulator guanethidine and α-adrenoceptor blocker phentolamine or selective α1-adrenoceptor antagonist prazosin over the medulla strongly attenuated all three MO-induced parameters of central sensitization in the MDH nociceptive neurons, compared to phosphate-buffered saline (as vehicle control). In contrast, i.t. superfusion of the selective α2-adrenoceptor antagonist yohimbine had little effect on the mechanoreceptive field expansion and the decreased mechanical activation threshold, and indeed facilitated responses to noxious stimuli of sensitized nociceptive neurons. Superfusion of each of the four chemicals alone did not affect baseline nociceptive neuronal properties. These findings provide the first documentation of the involvement of central noradrenergic processes in MDH in the development of the central sensitization, and that α1- and α2-adrenoceptors may be differentially involved.

Effects of enamel matrix proteins on proliferation, differentiation and attachment of human alveolar osteoblasts.

OBJECTIVES: Enamel matrix proteins (EMPs) have been demonstrated to promote periodontal regeneration. However, effects of EMPs on human alveolar osteoblasts (hAOBs), up to now, have still been unclear. The purpose of this study was to investigate influence of EMPs on proliferation, differentiation and attachment of hAOBs in vitro. MATERIALS AND METHODS: EMPs were extracted using the acetic acid method, hAOBs were obtained and cultured in vitro. Cell proliferation, alkaline phosphatase (ALP) activity, mRNA expression of osteogenic markers and cell attachment were measured in the absence and in the presence of EMPs (50, 100 and 200 µg/ml). RESULTS: EMPs increased proliferation of hAOBs; however, they inhibited ALP activity and mRNA expression of osteogenic markers (collagen I, ALP, runt-related protein 2, osteocalcin, bone sialoprotein and osteopontin). Meanwhile, EMPs hindered hAOBs' attachment. These effects occurred in EMPs concentration-dependent manner. CONCLUSIONS: These results indicate that EMPs may inhibit osteoblastic differentiation and attachment to prevent ankylosis and allow other cell types to regenerate periodontal tissues.

Age-related changes in biological characteristics of human alveolar osteoblasts.

OBJECTIVES: Age-related changes are common in many tissues and organs. However, cell-related causes in human alveolar bone remain unclear. This study has been carried out to explore the possibility that advancing age might change the biological characteristics of alveolar osteoblasts (AOBs) in women. MATERIALS AND METHODS: Alveolar osteoblasts from women donors (five women aged 33-38 years and five women aged 62-68 years) were cultured in vitro. The cells were serially passaged and maximal lifespan evaluated. Cell viability, ultramicrostructure and osteogenic differentiation ability were determined respectively, using MTT assay, transmission electron microscopy, alkaline phosphatase (ALP) activity assay and von Kossa staining assay. These parameters of the two groups of AOBs were evaluated. RESULTS: When compared with cells from young adult donors, AOBs from elderly women exhibited lower maximal lifespan (P < 0.05). Mean rate of population doubling was lower in elderly donor cells compared to those from young adult cells (P < 0.05). Organelles from AOBs of elderly donors were much fewer than those from young donors. MTT value of elderly donor cells was significantly lower than those of young adult donors from day 2 (P < 0.05). Relative ratio of ALP activity in elderly donor cells was significantly lower than those of the young womens' cells at 8, 12, 16 and 20 days (P < 0.05). Calcium nodules of young adult donors' specimens were significantly more numerous and larger than those from elderly donors. CONCLUSIONS: Comparison of biological characteristics of AOBs from young adult women with those from elderly women in vitro revealed differences in proliferative capacity and bone formation functions, which decreased with aging. These data indicate that aging may play an important role in pathogenesis of human AOBs loss.

Involvement of glia in central sensitization in trigeminal subnucleus caudalis (medullary dorsal horn).

Central sensitization is a crucial mechanism underlying the increased excitability of nociceptive pathways following peripheral tissue injury and inflammation. We have previously demonstrated that the small-fiber excitant and inflammatory irritant mustard oil (MO) applied to the tooth pulp produces glutamatergic- and purinergic-dependent central sensitization in brainstem nociceptive neurons of trigeminal subnucleus caudalis (Vc). Recent studies have implicated both astrocytes and microglia in spinal nociceptive mechanisms, showing, for example, that inhibition of spinal astroglial metabolism or spinal microglial p38MAPK activation can attenuate hyperalgesia in inflammatory pain models but have not tested effects of glial inhibitors on central sensitization in functionally identified spinal nociceptive neurons. The aim of the present study was to determine whether glial cells are involved in the MO-induced central sensitization in Vc nociceptive neurons, by examining the effects of intrathecally applied SB203580 (SB), an inhibitor of p38MAPK, and fluoroacetate (FA), an inhibitor of the astroglial metabolic enzyme aconitase. During continuous superfusion of phosphate-buffered saline over Vc, MO application to the pulp-induced central sensitization in Vc nociceptive neurons reflected in significant increases in cutaneous mechanoreceptive field (RF) size and responses to noxious mechanical stimuli and a decrease in mechanical activation threshold. The i.t. application of SB or FA markedly attenuated the MO-induced increases in pinch RF size and responses to noxious stimuli and the decrease in activation threshold. Neither SB nor FA application significantly affected the baseline (i.e., pre-MO application) RF and response properties. These results suggest that glial metabolic processes are important in the development of Vc central sensitization.

Endogenous ATP involvement in mustard-oil-induced central sensitization in trigeminal subnucleus caudalis (medullary dorsal horn).

Central sensitization represents a sustained hypersensitive state of dorsal horn nociceptive neurons that can be evoked by peripheral inflammation or injury to nerves and tissues. It reflects neuroplastic changes such as increases in neuronal spontaneous activity, receptive field size, and responses to suprathreshold stimuli and a decrease in activation threshold. We recently demonstrated that purinergic receptor mechanisms in trigeminal subnucleus caudalis (Vc; medullary dorsal horn) are also involved in the initiation and maintenance of central sensitization in brain stem nociceptive neurons of trigeminal subnucleus oralis. The aim of the present study was to investigate whether endogenous ATP is involved in the development of central sensitization in Vc itself. The experiments were carried out on urethan/alpha-chloralose anesthetized and immobilized rats. Single neurons were recorded and identified as nociceptive-specific (NS) in the deep laminae of Vc. During continuous saline superfusion (0.6 ml/h it) over the caudal medulla, Vc neuronal central sensitization was readily induced by mustard oil application to the tooth pulp. However, this mustard-oil-induced central sensitization could be completely blocked by continuous intrathecal superfusion of the wide-spectrum P2X receptor antagonist pyridoxal-phosphate-6-azophenyl-2, 4-disulphonic acid tetra-sodium (33-100 microM) and by apyrase (an ectonucleotidase enzyme, 30 units/ml). Superfusion of the selective P2X1, P2X3 and P2X(2/3) receptor antagonist 2',3'-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate (6-638 microM) partially blocked the Vc central sensitization. The two P2X receptor antagonists did not significantly affect the baseline nociceptive properties of the Vc neurons. These findings implicate endogenous ATP as an important mediator contributing to the development of central sensitization in nociceptive neurons of the deep laminae of the dorsal horn.