Evaluation of pH changes in inflammation of the subcutaneous air pouch lining in the rat, induced by carrageenan, dextran and staphylococcus aureus

The lowering of tissue pH in inflammation is generally accepted as the important mechanism for the failure of local anaesthesia in inflamed tissues. However, studies relating to pH changes in inflammation are scant in the literature and more importantly the findings are inconsistent. The purpose of this study is therefore to re-evaluate the pH changes using more reliable models of inflammation and pH measurement techniques. Wistar rats were used in the study. The inflammatory model used was based on the air pouch granuloma technique. Carrageenan, dextran and staphylococcus aureus were used as irritants and the pH measurements were made with a miniaturised glass tissue pH electrode designed by Roche. Results showed only a small lowering of pH in inflammation, of the order of about 0.5 pH unit. It may be possible that even such a small pH reduction would affect the buffer capacity of the tissues rendering the local anaesthetics less effective, but this needs to be confirmed with further studies.     

A retrieval study on morphological and chemical changes of titanium osteosynthesis plates and adjacent tissues.

AIM: To examine (a) morphological and chemical changes of retrieved titanium osteosynthesis plates, (b) findings in adjacent soft tissues during plate removal and to evaluate possible correlations among the above-mentioned issues. MATERIAL AND METHODS: Ninety-four osteosynthesis plates were retrieved, of which 60 were studied and evaluated (including the adjacent soft tissue) in more details, 4-36 months following osteosynthesis in 26 trauma cases, 12 orthognathic and 6 maxillofacial reconstructive cases. Selected clinical parameters during plate removal, were studied. Specialized laboratory methods including light and electron microscopy as well as spectrometry and X-ray microanalysis were used to analyse the retrieved material. RESULTS: Plates showed major mechanical changes (scratches, scraping and deformation) without corrosion. Soft tissue inflammation-mainly mild and chronic-was found in 53 of 94 plates removed, a statistically significant percentage. Pigmented deposits in the soft tissues manifested only traces of titanium when analysed elementally. There was no statistically significant correlation between the laboratory findings of plates and tissues, or between plate morphology and clinical findings recorded. CONCLUSIONS: According to the findings of this study, inflammation in tissues adjacent to osteosynthesis plates should not be attributed to mechanical changes in the plates. Pigmented tissue deposits were neither found to be titanium to the extent previously reported, nor were they correlated with tissue inflammation. These findings lead to the assumption that titanium plates do not have to be removed to avoid local inflammatory problems.     

Characterization of fibroblast clones from periodontal granulation tissue in vitro.

Connective tissues are known to be composed of heterogeneous fibroblast subpopulations. The significance of this heterogeneity in different physiological and pathological conditions is poorly understood. Granulation tissue is formed in connective tissue during wound healing, chronic inflammation, and certain pathological conditions. In this study, heterogeneity of fibroblasts from granulation tissue was investigated by cell-cloning techniques. Granulation-tissue fibroblasts (GTFs) from both chronically inflamed periodontal lesions and healing wound granulation tissue behaved similarly. GTFs showed a more pronounced decrease in proliferative capacity with increasing cumulative population doubling levels (CPDLs) and 30-40% lower cloning efficiency compared with normal gingival fibroblasts (HGFs). Morphologically, cells in GTF cultures were mainly large, whereas HGFs were mainly small in size. Both cell-line types showed heterogeneity in cell morphology. Clones composed of large stellate-like cells predominated in GTF cultures, whereas clones composed of small spindle-shaped or epithelioid cells predominated in HGF cultures. In both cell-line type the proportion of clones composed of large cells increased without increasing CPDL. These findings show that the properties of the fibroblasts changed during their in vitro life spans. The finding that normal connective tissue and granulation tissues contain morphologically distinct fibroblast clones in different proportions suggests that local factors could stimulate local fibroblasts to differentiate into GTFs. Alternatively, local factors could select some fibroblast subpopulations to overgrow the others to form granulation tissue.     

Immunity and inflammation as synergistic mechanisms in the pathogenesis of periodontal disease

The local immune response to challenge antigen injection in sensitized mice was investigated. Challenge injection was administered through the maxillary labial mucosa.
The influence of non-specific inflammation on the challenge response was studied when both were present simultaneously in a local oral tissue site. The results indicate that inflamed tissues react more violently to the presence of horse ferritin-anti horse ferritin complexes than do non-inflamed tissues. Although the challenge reaction in non-inflamed tissues incited an acute inflammatory lesion, this same reaction occurring in inflamed tissue induced an Arthus reaction.     

Inflammatory nerve responses in the dental pulp

Tooth pulp has a dense innervation and a rich vascular supply to maintain homeostasis and to preserve the integrity of the tissue. Function, trauma, and antigenic challenges make teeth and supporting tissues susceptible to tissue injury and inflammation, partially due to the lack of collateral blood and nerve supply and to their low compliance. This review focuses on dental nerve functions and adaptive changes in the pulpal nerve supply following inflammation and peripheral injury. Overviews of dental innervation and its development and of the peptidergic innervation of oral tissues are presented, followed by a discussion of peripheral and central changes after local insults to teeth and peripheral nerve injuries. The functional implications of these adaptive changes are considered.
Received 13 February 2009; accepted 3 September 2009.     

Effect of inflammation on the delivery of drugs to dental pulp

Although numerous studies have evaluated the effects of drugs on inflammation, comparatively few studies have evaluated the effects of inflammation on drugs. In this study, we have evaluated whether pulpal inflammation alters the delivery of flurbiprofen or Evan's blue, two agents that bind with high affinity to plasma proteins. The results indicate that pulpal inflammation alters the delivery of these agents to inflamed molars, that activation of capsaicin-sensitive nerves increases pulpal content of protein-bound agents, and that reduced pH increases free drug concentrations of flurbiprofen. Thus, alterations in both plasma extravasation and tissue pH seem to be relevant factors regulating the delivery and bioavailability of this nonsteroidal anti-inflammatory drug to dental pulp. Because many drugs used in endodontics (e.g. nonsteroidal anti-inflammatory drugs, clindamycin, bupivacaine, etc.) are heavily bound to plasma proteins, it is likely that the status of pulpal inflammation is a contributing factor in modifying the pharmacological efficacy of these agents.     

Effects of different retraction medicaments on gingival tissue.

OBJECTIVE: Exposure of the gingival sulcus and control of hemorrhage are prerequisites to the treatment of cervical lesions and improving the quality of impressions prior to fabricating indirect restorations. Gingival retraction cords saturated with different medicaments are widely used for this purpose. However, the long-term effects of the chemicals in gingival tissues are not clear. The purpose of this study was to compare the histopathologic effects of 2 different retraction solutions in gingival tissue. METHODS AND MATERIALS: In this in vivo study, a solution of 10% aluminum chloride and a solution of 15.5% ferric sulfate were used as retraction medicament in dogs. The saturated cords were allowed to remain in the gingival sulcus of the dogs for 3 minutes. After the removal of the cords, gingival biopsies were taken at 30 minutes, 24 hours, 7 days, and 12 days. For all specimens, histologic evaluation was performed by light microscopy to determine the degree of epithelial loss, alteration of the connective tissue, and inflammation. RESULTS: Histopathologic examination of gingival tissue revealed that the ferric sulfate solution caused significant changes in gingival tissues at the beginning. However, the tissue returned to its normal histologic appearance at the end of day 12. CONCLUSION: The results of this study revealed that the biologic effects of ferric sulfate solution are more satisfactory than aluminum chloride solution. However, both medicaments are reliable and can be used in gingival retraction.     

The influence of bacteria and irritation in the initiation of periodontal disease in germfree and conventional rats

Within the conditions of the experimental design, this study has provided laboratory evidence that microorganisms were necessary for the occurrence of inflammatory periodontal disease. Furthermore, this investigation has shown that the presence of both local irritation and microorganisms was necessary to produce periodontal inflammation. However, neither factor alone was capable of producing the inflammation. The results of this study have shown that a type of dental calculus may be formed in the absence of microorganisms. However, the same results have demonstrated that the presence of microorganisms greatly facilitates the formation of calculus. The presence of polymorphonuclear leukocytes in the gingival crevices and tissues could not be explained on the basis of bacteria and/or irritation. It was postulated that these cells are a normal component of the gingival tissues of these animals and that their presence does not constitute a pathologic process. The findings of the present study were considered with those of other studies. From this comparison it was suggested that differences in animal species and strains should be considered when evaluations and extrapolations of experimental results are made.     

Effect of lowering the pH of sodium hypochlorite on dissolving tissue in vitro

Sodium hypochlorite (NaOCl), a common antimicrobial and tissue-dissolving irrigant, comes from the manufacturer at pH 12. When the pH is lowered, NaOCl becomes more antimicrobial. The aim of this study was to examine what effect lowering the pH has on the property of tissue dissolution. Seven groups were tested for dissolving porcine muscle tissue at varying pH, concentrations, and times. When groups were examined solely by pH, there was no significant difference between the pH 12 and 9 groups, but a statistically significant level was found between pH 12 and 9 versus the pH 6 groups (P < .05). Higher concentrations and greater time periods all led to greater amounts of tissue dissolution.     

口腔黏膜下纤维性变的病因、致病机理、诊断与治疗

口腔黏膜下纤维性变是一种能形成瘢痕、组织纤维化的慢性疾病。流行病学研究显示,咀嚼槟榔是导致口腔黏膜下纤维性变的危险因素。在中国的口腔黏膜下纤维性变患者均有咀嚼槟榔的习惯。研究证实,嚼槟榔、吸烤烟和饮白酒可增加口腔黏膜下纤维性变的风险。口腔黏膜下纤维性变被广泛认为是一种口腔癌前病变,病理表现为慢性炎症、结缔组织内广泛的胶原纤维沉积、上皮固有层或其下结缔组织内的局部炎症改变。口腔黏膜下纤维性变的癌变发生率为7%~30%。口腔黏膜下纤维性变的治疗主要采用曲安奈德和丹参酮注射液行黏膜下局部注射,对改善患者的张口度及口腔黏膜的烧灼痛效果良好,其治疗总有效率可达93%。本文就口腔黏膜下纤维性变的病因、致病机理、诊断与治疗进行阐述,以供同道们临床参考之用。     

Hemomicrocirculation in oral mucosa of alveolar dental crests in cases of their considerable atrophy as determined by Doppler flowmetry

Doppler ultrasonography was used to study hemodynamic indices of blood circulation in gingival tissues in normal conditions and in cases of parodontal diseases. Such hemodynamic parameters as linear and volumetric blood speed were determined. It was shown that hemodynamic changes in tissue blood circulation in cases of initial inflammatory diseases had moderate intensity (decrease of linear and volumetric blood speed by 22-40%). As the severity of inflammation process in parodontal tissues increased (parodontitis of medium and severe degree) and in cases of parodontosis hemodynamic changes in tissue blood circulation acquired more pronounced nature (decrease of blood speed by 56-80%).     

Study of the chronic apical periodontitis influence upon the patient's organism status

During clinical-immunological study of the patients with chronic apical periodontitis (CAP) some differences were found between the following categories--CAP involving not more than 2 teeth and plural CAP. There were found the changes of both general immunity indices and its local components. Chronic inflammation course in periodontal tissues led to imbalance between cellular and humoral local immune reactions. It was shown that the presence of protracted multiple infectious focuses in periodontal tissues led to organism sensitizing and secondary immune deficiency.     

The collagenolytic activity in the mixed saliva, gingival fluid and gingival tissues of patients with periodontal inflammation]

Collagenolytic activity of mixed saliva, gingival fluid and tissue was radioimmunoassayed in 39 patients with periodontal inflammations. The findings evidence a significant elevation of this activity, correlating with the inflammation severity. Gingival fluid was found the most informative of the three studied biologic media for the assessment of the inflammatory destructive changes in periodontal tissues. Therefore it is preferred to use the gingival fluid in the biochemical studies for the early diagnosis of periodontal diseases.     

Changes in the cytoskeleton of cells within the periodontal ligament and dental pulp of the rat first molar tooth during ageing

The periodontal ligament and dental pulp connective tissues are foetal-like, and their process of ageing may therefore differ from other tissues of mesenchymal origin. Several studies have already highlighted the lack of age changes in the extracellular matrix (ECM), but more needs to be known about cellular changes. For this study, tissues from the first molar teeth of Wistar rats aged 12 wk and 104 wk were compared by immunolocalisation of cytoskeletal components. Tissues from the first molar were immunostained, employing a panel of 16 monoclonal antibodies against cytokeratins, vimentin, F-actin and tubulin. Within the pulp, labelling for vimentin in both odontoblasts and pulpal fibroblasts and F-actin in the cell processes of odontoblasts was detected at both ages but with marked reduction in labelling in the older tissue. Within the periodontal ligament, vimentin labelling was weaker in the aged tissue, especially nearer the cementum. More significantly, the fibroblasts of the aged periodontal ligament expressed cytokeratin 19. In contrast to reports of little age change to the ECM, the cells of the pulp, and particularly the periodontal ligament, show marked changes to their cytoskeletal components.     

Tissue reactions to biodegradable and non-degradable membranes placed transcutaneously in rats, observed longitudinally over a period of 4 weeks

summary The aim of this study was to observe the tissue responses to a number of membrane materials processed for use in guided tissue regeneration at different time periods. Non-degradable Gore-Tex° PTFE membrane and degradable polylactic acid (PLA) membranes were placed transcutaneously in surgical incisions made in the dorsum of rats. The tissue responses to these materials were observed histologically at 3 days, 1 week and 4 weeks after placement. A wide variation in the tissue responses to both materials was evident at each time period. These variations could not be attributed to different rates of healing over time, but rather to more complex factors. These factors may include differences in host responses between different animals, local factors pertaining to specific site variations, physical characteristics of the materials like surface texture, and contamination from the wound surface. Neither membrane material was found to be totally satisfactory. The PLA membranes were well tolerated by the tissues but they were unevenly absorbed within 2 weeks of placement. The Gore-Tex PTFE membranes, however, were associated with prolonged acute inflammatory infiltrate throughout the duration of the study, indicating that they were less well tolerated by the tissues than the PLA materials. As the healing characteristics of tissues are complex and highly variable, and as neither the non-degradable PTFE or degradable PLA membranes demonstrated ideal tissue responses, it is concluded that variations in clinical responses to these materials used in regeneration techniques must be anticipated.     

Interleukin-1beta,clinical parameters and matched cellular-histopathologic changes of biopsied gingival tissue from periodontitis patients

OBJECTIVE: The aim of the present study was to investigate whether interleukin (IL)-1beta in diseased tissues adjacent to periodontal pockets can reflect the degree of inflammation and destruction of these tissues pathologically. BACKGROUND: IL-1beta-dependent mechanisms have been strongly implicated in contributing to inflammation and destruction of bone and attachment loss, which are characteristic features of periodontal disease. This biochemical mediator released during pro-inflammatory processes has not been objectively integrated with clinical and histopathologic features of periodontal disease. METHODS: Periodontitis-affected inflamed tissue and clinically nonaffected healthy gingivae were harvested from 14 periodontal patients, respectively. The severity of tissue inflammation was illustrated by clinical parameters and cellular histologic changes and quantified by histometric assessments. IL-1beta in these extracted specimens was measured with an enzyme-linked immunosorbent assay (ELISA) technique. Pathogenic roles that IL-1beta plays in gingival inflammation and pathologic tissue changes in tissue sections were analyzed statistically. RESULTS: The overall total tissue IL-1beta, tissue concentration of IL-1beta, and percentage of inflammatory cell infiltration (PICI) determined from diseased gingivae were obviously higher than those of controls from both healthy sites of periodontitis and non-periodontitis subjects. With increasing gingival index (GI), plaque index (PlI), and probing depth (PD), there was a marked elevation in total tissue IL-1beta. Total tissue IL-1beta was significantly correlated with GI, PlI, the PICI, and tissue alterations. Polymorphonuclear leukocytes (PMNs) and monocyte-macrophage cells seemed to predominate in heavily infiltrated areas of diseased gingiva. These cell types were confirmed by immunocytochemical localization with either monoclonal mouse antihuman neutrophil elastase antibody or monoclonal mouse antihuman macrophage (CD68) antibody, respectively. Total tissue IL-1beta and the PICI were also elevated in diseased gingivae near deeper PD, while neither total IL-1beta nor tissue concentration was statistically correlated with PD. Thus, correlation analysis indicates that IL-1beta level in inflamed periodontal tissues correlates highly with clinical parameters (GI and PlI) and PICI (the degree of inflammation). CONCLUSIONS: These observations suggest that IL-1beta plays a significant role in the pathogenic mechanisms of periodontal tissue destruction, and that measurement of tissue IL-1beta would be a valuable aid and useful for diagnostic markers of periodontal diseases.     

Immunohistochemical localization of type IV collagen and laminin (α1) in denture stomatitis

Chronic clinical irritation of the palatal mucosa by dentures involves a series of histological changes in epithelial and connective tissues, inflammatory cells and the vasculature. No single change is pathognomic of this inflammatory process. The rupture of basement membrane associated with the development of denture stomatitis often marks an important stage. This study investigated modifications in basement membrane organisation, especially the distribution of type IV collagen and a specific laminin chain (alpha1), during denture stomatitis. Biopsies of palatal mucosa were obtained from 12 patients (8 with denture stomatitis and 4 with clinically healthy mucosa) who had worn removable dentures for more than 3 years. Immunohistochemical studies performed with specific antibodies to type IV collagen and a laminin (alpha1) revealed strong expression in the basement membrane of healthy palatal mucosa. In denture stomatitis, some discontinuities or disruptions in basement membrane were observed at the interface between connective tissue and epithelial cells. These findings suggest a relationship between the expression of laminin (alpha1) and type IV collagen and the development of denture stomatitis, a disorder involving modification of soft tissues in which initial inflammation of the palatal mucosa results from stress under the denture. These changes in basement membrane can be detected by histological studies.     

Maintenance and the clinical evaluation of periodontal patients in Konus-Telescope denture

In order to assess by periodontal evaluation the changes that might occur with time in the abutment teeth and periodontal tissues when Konus-Telescope dentures are used as that final treatment of periodontal disease, the dentures (15 units) were placed in 13 patients with missing tooth and periodontal disease and findings at the time of denture placement and 30 months after the placement were compared. The number of cases that exhibited significant changes in hygiene level, tissue inflammation and periodontal pocket depth of the abutment teeth after 30 months was very small, while as many as 85.2% of the abutment teeth showed decrease in tooth mobility. Increase in tooth mobility was not detected in any of the cases. In addition, X-ray examination revealed tendencies toward improvement of the periodontal ligament and remission of alveolar bone resorption in many of the cases. These results suggest that Konus-Telescope denture is highly offers protection of the residual periodontal tissues through its secondary splint action.     

Effect of pregnancy on periodontal and dental health

Clinical studies have shown that oral tissues can be affected by pregnancy. Pregnancy-related changes are most frequent and most marked in gingival tissue. Pregnancy does not cause gingivitis, but may aggravate pre-existing disease. The most marked changes are seen in gingival vasculature. Characteristic of pregnancy gingivitis is that the gingiva is dark red, swollen, smooth and bleeds easily. Women with pregnancy gingivitis may sometimes develop localized gingival enlargements. The gingival changes usually resolve within a few months of delivery if local irritants are eliminated. The inflammatory changes are usually restricted to the gingiva and probably do not cause permanent changes in periodontal tissues more often than those in the non-pregnant state. Although it is widely believed that pregnancy is harmful to the teeth, the effect of pregnancy on the initiation or progression of caries is not clear. Previous studies, however, indicate that the teeth do not soften, i.e. no significant withdrawal of calcium or other minerals occurs in the teeth. It is mainly the environment of the tooth that is affected. The number of certain salivary cariogenic microorganisms may increase in pregnancy, concurrently with a decrease in salivary pH and buffer effect. Changes in salivary composition in late pregnancy and during lactation may temporarily predispose to dental caries and erosion. Although their underlying mechanisms of action are not fully understood, pregnancy-related changes in the oral environment may have some untoward temporary or permanent effects on oral health. Most of these effects could be avoided by practising good oral hygiene.     

Effect of pregnancy on periodontal and dental health

Clinical studies have shown that oral tissues can be affected by pregnancy. Pregnancy-related changes are most frequent and most marked in gingival tissue. Pregnancy does not cause gingivitis, but may aggravate pre-existing disease. The most marked changes are seen in gingival vasculature. Characteristic of pregnancy gingivitis is that the gingiva is dark red, swollen, smooth and bleeds easily. Women with pregnancy gingivitis may sometimes develop localized gingival enlargements. The gingival changes usually resolve within a few months of delivery if local irritants are eliminated. The inflammatory changes are usually restricted to the gingiva and probably do not cause permanent changes in periodontal tissues more often than those in the non-pregnant state. Although it is widely believed that pregnancy is harmful to the teeth, the effect of pregnancy on the initiation or progression of caries is not clear. Previous studies, however, indicate that the teeth do not soften, i.e. no significant withdrawal of calcium or other minerals occurs in the teeth. It is mainly the environment of the tooth that is affected. The number of certain salivary cariogenic microorganisms may increase in pregnancy, concurrently with a decrease in salivary pH and buffer effect. Changes in salivary composition in late pregnancy and during lactation may temporarily predispose to dental caries and erosion. Although their underlying mechanisms of action are not fully understood, pregnancy-related changes in the oral environment may have some untoward temporary or permanent effects on oral health. Most of these effects could be avoided by practising good oral hygiene.