Engrafting periodontal fibroblasts with new 3-dimensional polylactide foams.

In clinical periodontics, "tissue engineering" techniques have been developed to guide the regenerative process following periodontal disease. We explored a new shaped biomaterial in order to promote cellular adhesion, proliferation and migration of periodontal cells. Granules of poly-D, L-lactide were foamed in specially designed moulds by a controlled gas-loading process. Explant cultures of periodontal tissue were seeded at different densities on the 3-dimensional scaffolds following analysis of cytotoxicity, cell proliferation and differentiation. The moulding procedure led to porous structures with predetermined tubes for cellular locomotion. Cells adhered to and populated the material's surface and inner cavities while retaining fibroblastic phenotype. An optimal ratio between cellular proliferation and mortality rate was achieved at a seeding density of > 10 6 cells/cm 3 scaffold. We designed modified polylactide scaffolds capable of acting as a stent and a cell carrier matrix. The foaming process is easy, cheap and suitable for commercial production.

Calcium solubility of dental enamel following sub-ablative Er:YAG and Er:YSGG laser irradiation in vitro.

BACKGROUND AND OBJECTIVE: The objective of the present study was to investigate the effect of sub-ablative Er:YAG (lambda = 2.94 microm) and Er:YSGG (lambda = 2.79 microm) laser radiation on the acid solubility of dental enamel. The influence of fluoride application prior to laser irradiation was additionally evaluated. STUDY DESIGN/MATERIALS AND METHODS: To this end, 294 enamel specimens were prepared from bovine teeth and divided into 14 groups of 21 specimens each. The enamel samples were irradiated in their groups with the Er:YAG and the Er:YSGG laser, using energy densities of 4, 6, and 8 J/cm(2) in each case. Irradiation was additionally repeated in the same way on specimens, which had previously been immersed in 1% sodium fluoride solution for 15 minutes. One group was left untreated and served as a control group. A further group was not irradiated, but only immersed in the 1% fluoride solution for 15 minutes. The enamel specimens were demineralised for 24 hours in an acetate buffer solution. The calcium content in the demineralisation solution was subsequently determined with the aid of atomic absorption spectrometry. RESULTS: The results indicate a decline in calcium solubility after laser irradiation. Compared to the control group, a 20% lower calcium content was detected in the demineralisation solution after irradiation with the Er:YSGG laser at 8 J/cm(2). The difference between the laser-irradiated groups and the untreated control group was, however, not statistically significant. A significantly lower calcium content was found in the demineralisation solution after fluoridation of the specimens. Additional laser radiation had no further effect on this result. CONCLUSIONS: In summary, it can be stated that, although the erbium laser wavelengths apparently have the potential to increase acid resistance, their application solely for caries prevention would not appear to be sensible under the prevailing conditions.

Monoclonal antibodies against integrin subunits alpha6 and beta1 inhibit migration of gingival epithelium in organ culture.

BACKGROUND: The main problem in the posterior instrumental treatment of periodontitis is the re-epithelization of the periodontal defects, leading to the formation of an unphysiological, long junctional epithelium inhibiting the regeneration of periodontal attachment. A precondition for the re-epithelization is the interaction between epithelial cells and their extracellular matrix mediated by integrins. Integrins are cellular adhesion molecules (CAM), binding to different structures of the extracellular matrix, e.g., collagen, laminin, or fibronectin. METHODS: Biopsy specimens of marginal gingiva, composed of epithelium and subepithelial connective tissue, were cultivated on microporous membranes in tissue culture plates. The culture medium was supplemented with monoclonal antibodies directed against human integrin subunits. The period of cultivation was 6 days and the medium was replaced daily. After cultivation, the tissue development was analyzed by histological and immunohistochemical methods. RESULTS: We found that the combination of antibodies directed against the integrin subunits alpha6 and beta1 inhibited the migration of epithelium completely in 9 out of 10 cultures, whereas control cultures containing none or only irrelevant antibodies demonstrated connective tissues completely covered by epithelium. CONCLUSIONS: Influencing the regeneration of periodontal tissue on a molecular basis by using antibodies directed against integrin subunits may be of future interest in postsurgical treatment of periodontal diseases.

Role of interactions between integrins and extracellular matrix components in healthy epithelial tissue and establishment of a long junctional epithelium during periodontal wound healing: a review.

Following the surgical treatment of adult periodontitis, the epithelial regeneration of the periodontal attachment is non-physiological and thus unsatisfactory, if membranes or artificial bone material are not used. Re-epithelialization is based on the proliferation, migration, and differentiation of basal epithelial cells which are in contact with a wound matrix and whose molecular makeup differs from the extracellular matrix of intact regions. Interactions between basal epithelial cells and the extracellular matrix are mediated by special receptors on the cell surface which are known as integrins and belong to the family of cellular adhesion molecules (CAM). Various studies indicate that integrin-mediated interaction plays a decisive role in regulating the proliferation, migration, and differentiation of the epithelial cells. This review provides an overview of the in vivo and in vitro expression of integrins by epithelial cells and the interaction between integrins and extracellular matrix (ECM) in the case of a stationary epithelium and during wound healing. The regulation of these cell-cell and cell-matrix interactions may represent a method for inhibiting non-physiological epithelial regeneration on the molecular level.

Distribution of fluoride in the oral cavity after application of a bioadhesive fluoride-releasing tablet.

Bioadhesive fluoride tablets are fluoride-releasing devices that can be applied to the oral mucosa by the patient and release fluoride for several hours. From earlier research, it is known that a single fluoride source in the mouth can lead to an uneven distribution of fluoride in the oral cavity. In this study, fluoride concentrations were determined at different sites of the oral cavities of 13 healthy human volunteers after the application of a bioadhesive fluoride tablet containing 0.5 mg fluoride. The sites were: (1) labial surfaces of the upper central incisors, (2) lingual surfaces of the lower central incisors, (3) labial surface of the first upper left molar, and (4) labial surface of the lower right first molar. The tablet was fixed either centrally on the palate or in the lower labial sulcus in two consecutive experiments. Saliva was sampled with polyethylene sponges 5, 10, 20, 30, 60, 120, 180, and 240 minutes after tablet insertion. Fluoride was determined electrochemically. It could be shown that the area under the curve (AUC) values were significantly (p < 0.05) higher after tablet insertion in the lower labial sulcus at sampling site 1, a trend (p = 0.06) could be calculated for sampling sites 2 and 3, and no difference was found at sampling site 4. Fluoride could be detected in concentrations above 0.01 mmol.L-1 at all sampling sites after tablet insertion in the lower labial sulcus. This location seems to be a more appropriate tablet location than the palate.

Penetration of etching agents and its influence on sealer penetration into fissures in vitro.

OBJECTIVES: This study was designed to assess: 1) the ability of several commercially available and laboratory-made acid etchants to penetrate occlusal fissures when used for pit and fissure sealing, and 2) the influence of adding a surfactant to the etchant on penetration of the sealer. Viscosity, surface tension and contact angle to enamel of the etchants were determined for each treatment, and these properties were related to the etchant's ability to penetrate fissures. METHODS: Penetration was assessed in an acrylic fissure model having a deep-narrow fissure using a microscope and a chronometer. Penetration depth was expressed as percentage of total fissure depth and was measured in intervals up to 90 s. Commercially available etching agents with different viscosities and two solutions of phosphoric acid (37%), one with and one without a surfactant, were tested. The etch pattern obtained on the fissure wall enamel of extracted teeth with some of these products was evaluated using scanning electron microscopy. Eventually, the penetration depths of a composite sealer in fissures treated with a conventional etchant were compared to those after application of a surfactant-containing etchant on sections of extracted teeth. RESULTS: None of the commercially available etchants studied were able to penetrate farther than 17% of the total fissure depth in the fissure model. The surfactant-containing etchant showed complete penetration within about 1 min and had a significantly lower surface tension and contact angle than the other products tested. Only the surfactant-containing etchant could produce a retentive pattern on the entire wall enamel of the fissure with the exception of locations blocked by debris and plaque. Fissures treated with this product prior to sealing showed a significantly deeper penetration of the sealer in deep-marrow fissures. SIGNIFICANCE: Surfactant-containing etchants with a low viscosity can penetrate completely into fissures and can produce an increased retentive and wettable surface which significantly increased sealant penetration into deep fissures.

[On the clinical aspects and ultrastructure of bullous pemphigoid (parapemphigus) of the oral mucous membrane (author's transl)]. / Beitrag zur Klinik und Ultrastruktur des bullösen Pemphigoids (Parapemphigus) der Mundschleimhaut.

Bullous changes in the oral mucosa are often the first signs of a general dermatological disease. Successful diagnosis of such diseases is largely dependent upon the use of complex laboratory methods. Clinical and ultrastructural changes are described and discussed with particular reference to a case of parapemphigus. Atypical intracellular vacuolation and marked acantholysis observed in electron micrographs is interpreted as a secondary phenomenon of direct blistering.

[Differential diagnostic significance of clinical gingival changes]. / Zur differentialdiagnostischen Bedeutung klinischer Gingivaveränderungen.

By way of introduction the author discusses the significance of periodontal disease symptoms in establishing a diagnosis and evaluates the various symptoms. The most important major and minor symptoms peculiar to the basic forms of periodontal disease are explained, and examples of the substantivation of clinical changes are given.