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Biomedical subjects

M Hannig

Publications and source records attributed to M Hannig.

At least 37 records · Page 2Linked to original sources
PubMed1999

In-vitro pulp chamber temperature rise during composite resin polymerization with various light-curing sources.

OBJECTIVES: The purpose of this in vitro study was to measure the pulp chamber temperature increase induced during composite resin polymerization with various visible light-curing units. METHODS: A Class II cavity was prepared in an extracted molar tooth, leaving a dentin layer 1 mm thick between pulp chamber and proximal cavity wall. A 2 mm composite resin layer was applied to the proximal box and light-cured with the selected curing units: Heliolux II (H; 320 mW/cm2), QHL 75 (Q; 505 mW/cm2), Astralis 5 (A; 515 mW/cm2), Optilux 500 (O; 670 mW/cm2), Elipar Highlight (EH; 730 mW/cm2), ADT 1000 PAC (P; 1196 mW/cm2). Light-curing took place for 40 s (H, A, Q, O, EH), 5 and 10 s (P). Measurement of pulp chamber temperature changes (starting temperature: 37.0 +/- 0.1 degrees C) during polymerization was performed with a K-type thermocouple positioned at the pulp-dentin junction. Mean values were calculated from 10 measurements with each light-curing unit. ANOVA and Dunnett t-test were used for statistical analyses. RESULTS: Maximum temperature changes varied significantly depending on the light-curing unit used: 2.9 +/- 0.3 degrees C (H), 4.7 +/- 0.5 degrees C (A), 5.4 +/- 0.3 degrees C (P, 5 s), 5.6 +/- 0.4 degrees C (Q), 6.1 +/- 0.2 degrees C (EH, 2-step mode: 100 mW/cm2 over 10 s, 730 mW/cm2 over 30 s), 6.9 +/- 0.4 degrees C (EH), 7.3 +/- 0.3 degrees C (O), 7.8 +/- 0.9 degrees C (P, 10 s). SIGNIFICANCE: It is concluded that light-polymerization with curing units characterized by high energy output (A,EH,O,P,Q) causes significantly higher pulp chamber temperature changes as compared to the conventional curing light (H). Therefore, clinicians should be aware of the potential thermal hazard to the pulp which might result from visible-light curing of composite resins.

Body Temperature↗
PubMed1999

Transmission electron microscopy of early plaque formation on dental materials in vivo.

This in vivo study describes the ultrastructural pattern of early plaque formation on various dental materials. Test pieces of amalgam, casting alloys, titanium, ceramics, glass polyalkenoate cement, composite resins, unfilled resins, and bovine enamel were attached to the buccal and lingual surfaces of the upper first molars in 3 subjects using removable intraoral splints. Specimens were exposed to the oral environment over a period of 24 h and subsequently processed for transmission electron microscopic evaluation. Only less pronounced variations could be detected in the ultrastructural appearance of the early plaque formed on the different material surfaces. However, electron microscopic observations revealed distinct differences in early biofilm formation between buccally and lingually mounted test pieces. While the bacterial colonization of specimens worn in the lingual position remained limited to the adherence of individual micro-organisms in the area of surface irregularities, a multi-layer adherence of micro-organisms was observed on all specimens carried in buccal areas. It is concluded that early plaque formation on solid surfaces is influenced predominantly by the oral environment rather than by material-dependent parameters. These findings may be ascribed to the presence of the pellicle layer, which apparently masks any difference among materials, with regard to surface properties and biocompatibility.

Adult↗
PubMed1999

Effects of air abrasion and acid etching on the microleakage of preventive Class I resin restorations: an in vitro study.

PURPOSE: To evaluate the effects of air abrasion, acid etching, and the combination of both procedures on the microleakage of preventive Class I resin restorations. MATERIALS AND METHODS: Eighty-four extracted human molar teeth were randomly assigned to seven groups with 12 teeth each. Occlusal fissures were opened with a diamond bur and etched with phosphoric acid (groups I and VI); prepared with a diamond bur without etching (group VII); air abraded with the KCP 1000, using 50-micron aluminum oxide particles without etching (group II), and with phosphoric acid etching (group III); or air abraded with 27-micron aluminum oxide particles without etching (group IV), and with phosphoric acid etching (group V). Preparations were filled with a low-viscosity resin composite (Liquicoat, groups I to V) or with a low-viscosity polyacid-modified resin composite (PrimaFlow, groups VI and VII). Six teeth in each group were thermocycled (5 degrees-55 degrees C, 2500 cycles). Dye penetration (methylene blue) was evaluated in ordinal scale. RESULTS: The number of non-thermocycled and thermocycled specimens revealing no microleakage was as follows: group I, 6 and 1; group II, 2 and 2; group III, 4 and 3; group IV, 0 and 0; group V, 1 and 0; group VI, 3 and 2; and group VII, 0 and 0, respectively. No significant differences existed between the thermocycled specimens and non-thermocycled specimens, except within group I. CLINICAL SIGNIFICANCE: Results indicated that (1) air-abrasion treatment with 27-micron particles is less effective in preventing microleakage compared to 50-micron particles, (2) air abrasion should be combined with acid etching to reduce microleakage of preventive Class I resin restorations, and (3) acid etching significantly reduces microleakage of the low-viscosity polyacid-modified resin composite in preventive Class I restorations.

Acid Etching, Dental↗
PubMed1997

Analytical and ultrastructural studies of pellicle on primary teeth.

The pellicle on permanent enamel has been thoroughly studied. The aims of this study were to compare the chemical composition, rate of formation, and ultrastructural appearance of pellicle formed on deciduous enamel in children with those on permanent teeth. This was done by amino acid analyses, Auger analyses, and transmission electron microscopy. The amino acid composition of 2-h pellicle on deciduous and permanent enamel had an overall similar pattern, but the contents of serine, glycine, and tyrosine were statistically significantly different. An initially slower pellicle formation and a thinner 2-h pellicle without a globular structured second layer was observed on deciduous enamel. The results indicated therefore distinct differences in chemical composition, rate of formation, and ultrastructural appearance between pellicle on primary teeth and that on permanent teeth.

Amino Acids↗
PubMed1997

Transmission electron microscopic study of in vivo pellicle formation on dental restorative materials.

This electron microscopic investigation was performed to examine the ultrastructure of the in vivo formed salivary pellicle on 15 different dental materials. Test pieces of amalgam alloys, casting alloys, titanium, ceramics, resins, composite resins, glass polyalkenoate cement, and bovine enamel were attached to the buccal and lingual surfaces of the upper first molars in three adults using removable intraoral splints. The splints were carried over periods of 2 and 6 h. Pellicle-like structures could be identified on all tested material surfaces by transmission electron microscopic analysis. The pellicle layer showed a high degree of similarity on different kinds of surfaces with regard to the ultrastructural appearance. However, distinct differences could be detected in the ultrastructural pattern and thickness of the pellicle layer formed on buccally and lingually mounted specimens. Pellicles adsorbed on buccally carried test pieces were characterized by a heterogeneous, globular appearance and a thickness ranging from 500 to 1,000 nm after 6 h. In contrast, all lingually mounted test pieces were covered by a granular pellicle of about 100 nm thickness after 6 h. It is concluded that the ultrastructural pattern and extent of salivary pellicle formation are influenced by locally available salivary biopolymers and locally effective shearing forces rather than by material-dependent parameters.

Adsorption↗
PubMed1997

Esthetic posterior restorations utilizing the double-inlay technique: a novel approach in esthetic dentistry.

The employment of adhesively bonded porcelain or resin composite inlays is considered problematic in Class II cavities extending into the dentin and cannot be recommended as a routine procedure for current clinical practice. A two-part restoration in the form of a double inlay provides an alternative to the clinically established gold inlay restoration. The double inlay is composed of a conventionally cemented metal base and an adhesively bonded porcelain inlay. After the metal substructure is coated with silica or a microretentive opaque glaze is fired, the porcelain inlay can be luted to the metallic base with a bonding resin composite. This procedure incorporates the advantages of cast restorations at the critical cervicoproximal cavity margin and the esthetic and stabilizing properties of the adhesively bonded restoration technique in visible areas.

Bicuspid↗
PubMed1992

Influence of buffered and unbuffered acetylsalicylic acid on dental enamel and dentine in human teeth: an in vitro pilot study.

An in vitro study was conducted to investigate the erosive effect of buffered and unbuffered acetylsalicylic acid (ASA) on dental enamel and dentine in human teeth by scanning electron microscopy. In order to standardize the specimens and to improve comparability the dental enamel and dentine were superficially abraded. The enamel and dentine specimens were therefore particularly sensitive to the influences of acid agents. Concentrated solution of buffered chewable ASA tablets (500 mg ASA and 300 mg calcium carbonate in 5 ml water) showed no changes in the enamel surface structure after exposure times of 1 min, 5 min and 60 min. In contrast, minimal corrosive effects were already seen after exposure of the enamel surface to the unbuffered ASA solutions for 1 min. After exposure times of 5 min and 60 min erosion of the enamel was more pronounced. Immersion in the unbuffered ASA solution led to clearly visible micromorphological changes on the dentine surfaces even after exposure for 1 min. Exposure of the dentine specimens to the buffered ASA solutions led to only very slight changes in the surface morphology. Therefore, the scanning electron micrograph after exposure to buffered ASA is comparable to the picture of untreated dentine.

Aspirin↗
PubMed1991

[SEM study on the finishing of glass ionomer cement filling surfaces].

The surfaces produced by different finishing techniques at two different time intervals following placement of three glass ionomer cements are compared by SEM-evaluation. All finishing procedures impaired the surface texture obtained under a matrix strip. Finishing of glass-ionomer cement restorations is best performed with flexible discs at 24 hours after placement. Initial finishing after 15 minutes using water spray is detrimental to the glass-ionomer cement surface. A useful procedure is to apply a lubricant during finishing of the cement.

Cermet Cements↗
PubMed1991

[The effect of modified forms of preparation on the quality of SR Isosit composite inlay margins].

Butt joint, plain and round beveled MOD cavities were prepared in extracted human molars. Composite resin inlays (SR-Isosit) were fixed adhesively and analysed by quantitative SEM-evaluation after thermocycling and mechanical load application. The marginal adaptation of the inlays differed significantly depending on the type of cavosurface preparation. Best results with a high percentage of perfect margins not only before but also after in vitro load application were obtained with cavities prepared with rounded bevels.

Acrylic Resins↗
PubMed1991

[Marginal behavior of "Kulzer" composite inlays under simultaneous mechanical and thermal loading].

This in vitro study assessed the marginal behavior of the "Kulzer"-inlay using two different resin luting agents (Adhesive cement resp. Tulux-Cem). SEM-evaluation after combined mechanical and thermal loading revealed significant differences in the marginal seal of the inlays depending on the luting composite resin used. "Kulzer"-inlays luted with Adhesive cement showed of rate a excellent margins of more than 90% even after in vitro load application, while the rate of perfect margins were less than 80% for "Kulzer"-inlays inserted with Tulux-Cem.

Composite Resins↗
PubMed1991

[Marginal adaptation of SR-Isosit composite inlays. In vivo results after 12 months].

The present in vivo study assessed the marginal behaviour of in total 43 "SR-Isosit" composite inlays. SEM-analysis of replica models indicated a continuous loss of marginal adaptation within the one year period of clinical use. Cavomarginal degradation predominantly took place on the contact surface between composite resin inlay and resin luting agent by (micro-)fractures of thin and instable inlay margins.

Acrylic Resins↗
PubMed1991

[Optimizing accuracy of Isosit IO composite restorations].

Using a modified technique for producing composite inlays from Isosit IO resin material resulted in an optimized accuracy of inlays primary fit. SEM evaluation of MOD composite resin inlays manufactured by this technique and inserted on extracted teeth showed that the mean thickness of the luting composite space measured less than 50 microns.

Acrylic Resins↗
PubMed1990

[Accuracy of fit and margins of laboratory-finished SR-Isosit composite inlays].

30 inlays were produced exactly by manufactures instruction using the SR-Isosit composite. Before cementation the marginal gaps of the inlays extended to 280 microns occlusal resp. to 350 microns gingivoproximal. After insertion the thickness of the luting composite ranged from 40 to 400 microns occlusal resp. from 40 to 470 microns gingivoproximal. Dye penetration test indicated that only 43.7% of the inlays had a good marginal behaviour after storage in water over a six month period. Particularly remarkable was the insufficient junction between the luting composite and the highly polymerized inlay.

Acrylic Resins↗