Evidence of chemical bonding to hydroxyapatite by phosphoric acid esters.

Phosphoric acid esters (PAEs) have been used as a self-etching primer for composite-to-enamel bonding in adhesive dentistry. However, the chemical mechanism of their interactions with hydroxyapatite (HA) is not clear. In the present study, HA particles were mixed with Resulcin AquaPrime (Merz Co.

Enzymes in the acquired enamel pellicle.

The acquired pellicle is a biofilm, free of bacteria, covering oral hard and soft tissues. It is composed of mucins, glycoproteins and proteins, among which are several enzymes. This review summarizes the present state of research on enzymes and their functions in the dental pellicle.

Cytochemical differences in bacterial glycocalyx.

To examine new cytochemical aspects of the bacterial adhesion, a strain 41452/01 of the oral commensal Streptococcus sanguis and a wild strain of Staphylococcus aureus were grown with and without sucrose supplementation for 6 days. Osmiumtetraoxyde (OsO4), uranyl acetate (UA), ruthenium red (RR), cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs), and the tannic acid-metal salt technique (TAMST) were applied for electron microscopy. Cytochemically, only RR-positive fimbriae in S.

Assessment of enamel erosion and protective effect of salivary pellicle by surface roughness analysis and scanning electron microscopy.

Purpose: To assess dental erosion caused by 0.1% and 1.0% citric acid in vitro and to estimate the protective influence of experimentally formed salivary pellicle.

Do different implant surfaces exposed in the oral cavity of humans show different biofilm compositions and activities?

Osseointegrated dental implants play an important role in restorative dentistry. However, plaque accumulation may cause inflammatory reactions around the implants, sometimes leading to implant failure. In this in vivo study the influence of two physical hard coatings on bacterial adhesion was examined in comparison with a pure titanium surface.

Electron microscopic detection of salivary alpha-amylase in the pellicle formed in situ.

Immunological and biochemical analyses have shown that alpha-amylase is an essential component of the acquired pellicle. After adsorption, this enzyme might act as a receptor for bacterial adherence. However, data indicating that amylase is bound to the pellicle surface in vivo and thus available for adhering bacteria are rare.

Initial salivary pellicle formation on solid substrates studied by AFM.

Organic layers of salivary biopolymers adsorbed on soft and hard oral tissues, referred to also as salivary pellicle, play a critical role with respect to all surface phenomena taking place in the oral cavity. The initial stages of pellicle formation are of great interest since they determine the ensuing processes of salivary biopolymer adsorption and subsequent adherence of bacteria. In spite of the important physiological role of the pellicle in protecting the enamel surface against short-term acidic attacks, the composition and ultrastructure of the pellicle layer are not yet understood and resolved in detail.

Transmission electron microscopy comparison of methods for collecting in situ formed enamel pellicle.

The in vivo formed salivary pellicle is composed of an outer globular and a densely structured basal layer. This study developed a method for selective recovering of these pellicle layers from the enamel surface. Two-hour in situ pellicles were formed by intraoral exposure of enamel specimens in two adults.

Protective effect of the in situ formed short-term salivary pellicle.

Salivary pellicle, as previously investigated, protects the enamel surface after certain processes of maturation against the influence of acidic agents. The aim of the present study was to investigate the protective effect of the short-term salivary pellicle formed in situ over periods of 3, 60 and 120 min. Six human volunteers used intraoral acrylic splints with bovine enamel samples fixed at the buccal and palatal sites of the maxillary first molars and second premolars.

Evidence of chemisorption of maleic acid to enamel and hydroxyapatite.

Maleic acid has been used as an etchant or non-rinse conditioner in adhesive dentistry. However, the inherent mechanisms of the interaction of maleic acid with hydroxyapatite/enamel have never been fully elucidated. The purpose of this study was to provide evidence for the chemisorption of maleic acid onto hydroxyapatite/enamel, and to identify the reaction products obtained following the interaction of maleic acid with hydroxyapatite.

Supramolecular pellicle precursors.

Saliva contacting with solid surfaces in the oral cavity forms a coat termed the pellicle. However, its formation is not fully understood. Although indications for the existence of supramolecular pellicle precursors have been reported, the possible relationship between them and pellicle formation is unclear.

Immobilisation and activity of human alpha-amylase in the acquired enamel pellicle.

Unlabelled: Amylase is an important salivary component and structural element of the acquired enamel pellicle. Aim of the study was to establish a method for precise and direct determination of pellicle bound amylase activity in order to analyse kinetics and activity of the immobilised enzyme. Six bovine enamel slabs (5mm diameter) were fixed on individual maxillary trays and worn by five subjects for different times (3, 30 and 120 min) on buccal and palatal sites on different days.

Microleakage and SEM evaluation of fissure sealants placed by use of self-etching priming agents.

Objectives: This study evaluated the microleakage and internal seal of fissure sealants placed by use of self-etching priming agents in comparison to phosphoric acid etching of enamel.

Methods: Seventy-two caries-free extracted human molars were divided into six groups with 12 teeth each. Occlusal surfaces were cleansed by either pumicing (Groups I, III, V) or by 15-s air-abrasion treatment with 25 microm aluminum oxide particles (Groups II, IV, VI).

Influence of salivary pellicle formation time on enamel demineralization--an in situ pilot study.

This study assessed the protective potential of salivary pellicles formed in situ over periods ranging from 2 to 24 h. Pellicles were produced on enamel slabs mounted on the palatal aspect of removable acrylic splints and exposed to the oral environment in three subjects for 2, 6, 12 and 24 h. Enamel specimens with and without pellicles were immersed in citric acid (1%) for 60 s, and the amount of dissolved calcium was measured by atomic absorption spectroscopy.

Glycocalyx morphology of Candida albicans.

In this study, we examine new cytochemical aspects of the fimbria-mediated adhesion of the oral facultative pathogen Candida albicans. A wild-type strain of the yeast was grown with and without sucrose supplementation for 8 days. Osmium tetroxide, uranyl acetate (UA), ruthenium red (RR), and cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs) and tannic acid-metal salt technique (TAMST) were applied to specimens separately or in combination for transmission electron microscopy (TEM) examination.

Effect of different luting materials on the marginal adaptation of Class I ceramic inlay restorations in vitro.

Objectives: The aim of this in vitro study was to assess the marginal adaptation of prefabricated Class I ceramic inlay restorations placed with various luting materials.

Methods: Forty-two standardized occlusal cavities were prepared in extracted human molars with diamond burs exactly corresponding to the dimensions of prefabricated glass ceramic inlays. The prepared teeth were randomly assigned to seven groups of six teeth each and restored using (1).

[Effect of self-etching primers on microleakage of resin composites in class V restorations].

OBJECTIVE: To evaluate in vitro microleakage of class V restorations using two self-etching primers with a flowable resin or hybrid resins. METHODS: Forty human molars were divided into 3 groups according to axial surfaces. Each group was randomly assigned to 2 subgroups (n=20) with either butt-joint or the beveled preparations.

Candida-induced stomatopyrosis and its relation to diabetes mellitus.

Background: Glycaemic disorders and oral candidosis can be accompanied by burning mouth sensations. However, no clear relation between all three disorders is known.

Methods: Seventy-two native Upper-Austrians with burning mouth sensations were examined and smears for Candida estimation were taken from the spots where the sensations were felt.

Inter-crystallite nanoretention of self-etching adhesives at enamel imaged by transmission electron microscopy.

The purpose of this in vitro study was to analyse the mode of action of self-etching adhesive systems when applied for resin-to-enamel bonding. Transmission electron microscopy was used to investigate the enamel-resin interface after application of non-rinsing self-etching adhesive systems based on phosphoric acid estered methacrylates (Clearfil Liner Bond 2, Clearfil SE Bond, Etch & Prime 3.0 and Resulcin AquaPrime) compared with conventional phosphoric acid etching and bonding (Heliobond).

[Effectiveness of various whitening techniques and their effects on the enamel surface].

The objective of this in vitro study was to compare three different bleaching techniques with respect to the bleaching times required to achieve six grades of whitening in human teeth, i.e. from shade A4 to A3 of the VITAPAN classical shade guide.

Bacterial adhesion to sulcular epithelium in periodontitis.

The purpose of this study was to investigate, by electron microscopy, the type of bacterial attachment to the sulcular epithelium in periodontitis. Gingiva biopsies were observed in a transmission electron microscope using cytochemical staining with ruthenium red for glycocalyx visualisation. In addition, subgingival plaque samples and biopsies from the sulcular epithelium in periodontitis from the patients were estimated microbiologically.

Candida attachment to oral epithelium.

Inflamed oral mucosa biopsies from patients with thrush and high candidal density were observed in a transmission electron microscope (TEM) using ultra-histochemical staining with ruthenium red for glycocalyx visualization. Fimbriae comprising the glycocalyx and enabling yeast adhesion to epithelial cells were clearly visualized by ruthenium red. All internalized portions of the yeast walls were devoid of glycocalyx, indicating that the growing tips of the hyphae mechanically penetrated the host cells.

Effect of air abrasion and resin composite on microleakage of Class V restorations bonded with self-etching primers.

Purpose: The purpose of this in vitro study was to determine the effect of air-abrasion pretreatment on microleakage of Class V resin composite restorations bonded with self-etching primers.

Materials And Methods: A total of 54 Class V cavities prepared either with diamond burs or air abrasion (KCP 1000) was restored with resin composites using adhesive systems with self-etching priming agents (Clearfil Liner Bond 2 or Resulcin AquaPrime + Monobond) and thermocycled 2,500 times. The degree of dye penetration (0.

Fimbria-mediated bacterial adhesion to human oral epithelium.

Oral mucosa biopsies and saliva samples from 12 individuals were processed for transmission (TEM) and scanning (SEM) electron microscopy with and without ruthenium red staining. Additionally performed microbiological estimations indicated in all bacteriological samples a facultative pathogenic flora. SEM and TEM investigation showed a diverse bacterial flora attached to the mucosal surface.

In vitro study of enamel and dentin marginal integrity of composite and compomer restorations placed in primary teeth after diamond or Er:YAG laser cavity preparation.

Purpose: The aim of this in vitro study was to evaluate the effect of laser vs diamond instruments on Class II and Class V cavity margins in primary teeth with SEM after restoration with composite and compomer materials and subsequent thermocycling.

Materials And Methods: Class V cavities with margins completely located in enamel were prepared in 36 extracted primary teeth to examine the restoration-enamel interface. Eighteen cavities were prepared with an Er:YAG laser operated at 3 Hz, 300 mJ/pulse, and 18 with a spherical fine diamond bur.