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Biomedical subjects

F Lutz

Publications and source records attributed to F Lutz.

At least 91 records · Page 5Linked to original sources
PubMed1994

Mesio-occlusodistal amalgam restorations: quantitative in vivo data up to 4 years. A data base for the development of amalgam substitutes.

Wear and marginal quality of 14 mesio-occlusodistal amalgam restorations (Dispersalloy) were quantitatively analyzed in this in vivo study. Wear rates, measured as maximum vertical loss of substance in the occlusal contact area, were 41, 50, 57, 79, 82, 123, 165, and 215 microns after 1, 2, 3, 6, 9, 24, 36, and 48 months, respectively. In the contact-free occlusal area an expansion of 2 to 9 microns was recorded. The micromorphology of the tooth-amalgam interface significantly changed within the first 9 months after restoration placement. The percentages of marginal opening increased from 91% to 100%, marginal restoration fracture from 49% to 89% and underfilled margin from 50% to 78%. Amalgam restorations have clinically proved successful despite their poor marginal adaptation and their inferior wear resistance compared to enamel. Thus, the wear resistance of amalgam substitutes, preferably metal-free, tooth-colored restorative materials, would not necessarily have to exceed that of amalgam to replace it. The wear data generated may serve as guiding figures in the development of amalgam substitutes.

Adult↗
PubMed1994

Wear of CAD/CAM ceramic inlays: restorations, opposing cusps, and luting cements.

Six standard mesio-occlusodistal restorations in extracted mandibular human molars and six opposing palatal cusps from maxillary human first molars were prepared per group. The occlusal contact areas of the restorations and of the opposing enamel cusps were digitized with a three-dimensional scanner. The specimens were exposed to a clinically correlated long-term in vitro wear test. Dicor MGC, Cerec Vita Mk I porcelain, Cerec Vita Mk II V7R porcelain, and Cerec Mk II Vita V7K porcelain were tested. The mean wear of these ceramic materials at the end of the long-term test ranged from 24.3 +/- 10.3 microns (Cerec Vita Mk II V7R) to 88.0 +/- 37.3 microns (Dicor MGC). The mean wear of the opposing human enamel cusps ranged from 93.5 +/- 30.8 microns (Cerec Vita Mk II V7R) to 224.3 +/- 117.4 microns (Cerec Vita Mk I). All ceramic materials except Dicor MGC wore less than did previously measured standards, such as natural human enamel and amalgam. However, because the wear of opposing enamel cusps was high with Dicor MGC and with Cerec Vita Mk I the total wear of these two materials--the sum of the restoration's and the opposing tooth's wear--was higher than that of the standards. Only the new fine porcelain Cerec Vita Mk II V7R showed a total wear comparable to that of enamel, because of its moderate abrasivity against opposing enamel. The wear of the two luting composite resins was measured at the end of the test. Both luting composite resins wore more than did the ceramic inlays and surrounding enamel, leaving a shallow ditch around the restorations.

Ceramics↗
PubMed1994

[Composite polymers--an amalgam substitute for deciduous tooth cavities?].

In this prospective clinical study, 29 class II restorations in deciduous teeth were placed in 17 patients using the recently developed compomer Dyract. The restorations were clinically and macrophotographically evaluated immediately after placement and after 6 months in situ. In addition, marginal adaptation and loss of substance were quantitated using replicas. Clinical and macrophotographical findings were excellent. Quantitative marginal analysis scored 92.5% "continuous margin" immediately after placement of the restorations and 95.4% after 6 months. Mean loss of substance at the margins of the restorations was 20.8 microns with a standard deviation of 64.6 microns. Providing that the positive results of this short term study are confirmed by long term data, Dyract may replace amalgam in deciduous teeth.

Child↗
PubMed1994

Release of preventive agents from pacifiers in vitro. An introduction to a novel preventive measure.

Clinical data show that the later primary teeth are colonized by mutans streptococci (MS), the less caries will develop, if at all. Since up to 90% of teething children develop a sucking habit, pacifiers were designed to release preventive agents into the mouth. Simultaneous use of sodium fluoride and xylitol increases the enamel fluoride content. Xylitol affects specifically growth and metabolism of mutans streptococci. The aim of this study was to determine the release of fluoride, xylitol and sorbitol from pacifiers in vitro. A disintegration apparatus was designed to test the dissolution of tablets containing NaF resp. 0.25 mg F, 160 mg xylitol and 150 mg sorbitol from the pacifiers. Six pacifiers were agitated simultaneously with a standardised pump movement, 30 strokes/min, in 15 ml normal saline at +37 degrees C for 2, 5, 10, 20, 40, 60 and 90 min. The released fluoride was determined in 1 ml samples of saline to which 1 ml Tisab was added using a combined F-ion electrode. Xylitol and sorbitol were analyzed by using an ion chromatograph with a pulsed-amperometric detector. A linear slow release of fluoride, xylitol and sorbitol from the pacifiers could be observed up to 90 min. After 2700 strokes the residual saline in the suction chambers (vol. approximately 0.4 ml) was equally analyzed, where all 3 ingredients could still be detected.

Cariostatic Agents↗
PubMed1994

[An empirical report on fissure sealing in private practice with a duration of up to 10 years].

This study reports a follow-up on 2415 occlusal sealings performed in a dental office. After nine to ten years service time, the survival rate of all sealed surfaces dropped to 69.5% because of either occlusal or interproximal carious activities. Retention of the sealings was intact in 91.5% after one year, but dropped to 58.2% after nine years. In the control group 49.3% of the grooves showed either caries or fillings during the last check-up whereas this occurred in only 7.3% of the sealed teeth (ratio 7:1). The difference among those two groups was even bigger (45.7% vs. 5%, ratio 9:1) when excluding all two-sided fillings. The costs of restoring one tooth surface in the control group was on average two to three times higher than for the sealings group. There is no doubt about the beneficial prophylactic effect of the use of sealants, even in the context of the private dental office, and no inconvenient side-effects have been found. The results concerning the retention rate of sealing in this study from a private dental office are comparable with the average of those reported in many papers from U.S. Dental Schools, they are even slightly better for the caries incidence.

Adolescent↗
PubMed1994

[A new method for 3-dimensional wear measurement].

This study described a custom-made three-coordinate measuring system. It was based on a mechanical digital measuring device, a measuring and overlapping software and special specimen holders. The x-/y-measuring area was 100,000 x 100,000 microns and the vertical measuring range was 30,000 microns. The measurements were reproducible within the resolution of 1.0 microns over the entire measuring range. The maximum measurable tilt relative to the horizontal plane was < 59 degrees. The total accuracy of the system, which was influenced by the resolution of the measuring device, the reproducibility of the measurements, the accuracy of the test sample reposition and the measuring/overlapping software was better than 1.0 microns. For the graphic presentation of the data commercial software was adopted. Its capabilities were demonstrated on selected examples. The measuring system is an efficient device, which is extremely well adopted to the problem of quantitative wear measurement in dentistry.

Dental Materials↗
PubMed1994

[Oral health: self-care and dental care: strategies for the patient and the practice. A continuing education course of the Division for Preventive Dentistry, Periodontology and Cariology, the Dentistry Institute of the University of Zurich in cooperation with the Clinic for Periodontology and Dental Bridgework, the Dental Clinics of the University of Bern and the Study Club ARP of 29 and 30 October 1993 in Zurich-Regensdorf: A factual summary].

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Dental Care↗
PubMed1994

["Adhesive anterior tooth restorations" with the use of dentin bonding with and without a cavity liner].

In this clinical study 60 class III and class IV restorations were placed according to the rules of the "adhesive restoration". 32 were without, 28 with a light-cured glass-ionomer liner. Total bonding was established in the liner-free group using a modern dentinal adhesive (Prisma Universal Bond 3). Immediately after placement and 3, 6 and 12 months later, respectively, all restorations were clinically inspected. In addition, marginal adaptation of 29 fillings was evaluated in the scanning electron microscope using the replica technique. The results of the clinical examination and of the SEM evaluation at 12 months were not statistically different. Clinically, all restorations were rated A or B. Except for one tooth with pulpitis caused by a restoration, that was not directly involved in this study, all restored teeth were vital and free of clinical symptoms after 12 months. The percentage of "continuous margin" was about 90% in both groups initially. At 12 months-recall, more than 95% "continuous margin" were recorded. This increase was due to repeated removal of flashes at the recall intervals. Under the proviso of an efficient recall, by using a modern dentinal adhesive and a fine hybrid composite, "adhesive restorations" can successfully be placed with and without liner.

Cuspid↗
PubMed1994

Clinical and SEM study of Tetric resin composite in posterior teeth: 12-month results.

Thirty-nine conventional posterior composite fillings were placed according to the three-sited light curing technique using Tetric, a fine hybrid composite material, and Syntac, a dentin adhesive. Six and 12 months later, the restorations were clinically evaluated using macrophotographs. A quantitative marginal analysis was also done immediately after placing the restorations and at the two recall intervals using a replica technique and an SEM. Contour, secondary caries, postoperative sensitivity and bulk fractures all rated "A" at 12 months. Marginal discoloration and color match were scored as 97% "A" and 3% "B". The SEM evaluation of the marginal adaptation showed 95% "continuous margin" initially and 93% at 6 months and 89% at 12 months. No statistical difference was found between the initial findings and the 12-month recall between premolars and molars, nor between small and large restorations. The overall performance of the new composite material during the 12-month observation period was satisfactory.

Bicuspid↗
PubMed1993

Pseudomonas aeruginosa cytotoxin-binding protein in rabbit erythrocyte membranes. An oligomer of 28 kDa with similarity to transmembrane channel proteins.

Rabbit erythrocyte membrane glycosylated 28-kDa protein was investigated in the membrane-bound as well as in the soluble state on an example of a Pseudomonas aeruginosa cytotoxin-binding component. When membranes were treated with trypsin/N-glycosidase F, a 13.5-kDa-binding active peptide residue is obtained as revealed by a ligand-blot technique after separation by SDS/PAGE under reducing conditions and electrophoretic transfer to nitrocellulose. Target-size analysis of intact membranes by radiation inactivation using 2-450 kGy gave a value of 29, 40 and 60 kDa for the binding-protein structure. This suggests that the native form of the binding peptide is associated as an oligomer. As seen in ligand-blot technique, 125I-cytotoxin binds with high affinity to water-channel integral protein CHIP28 from human erythrocyte membranes. The 20 N-terminal amino acids of the deglycosylated rabbit cytotoxin-binding protein show high similarity to transmembrane channel-like proteins.

Amino Acid Sequence↗
PubMed1993

Nucleotide sequence of attP and cos sites of phage CTX and expression of cytotoxin in Pseudomonas aeruginosa PA158.

The gene for Pseudomonas aeruginosa cytotoxin (CTX) has been found to be part of a temperate phage with a total size of 35.5 kb. We have investigated several DNA fragments of this phage for CTX production. For phage integration, the phage genome cohesive (cos) ends covalently associate with host DNA of strain PA158. The cos ends and the CTX gene are found on a 3.4 kb EcoRI fragment B and are included in the 11 kb HindIII fragment A and the 8.5 kb BamHI fragment B of the phage DNA. The cos ends are 20 nucleotides long and are located at 338-357 nucleotides upstream of the CTX transcriptional initiation site. The phage attachment (attP) site is also present on the 3.4 kb EcoRI fragment B. The attP site consists of 34 bp and is located at 974-1007 nucleotides upstream of the CTX gene start site. Replication of the vegetative form of the phage is increased at 37 degrees C compared to that at 30 degrees C, while cytotoxin production in infected cells is similar at 30 degrees C and 37 degrees C. It can be concluded, therefore, that the integrated form of the CTX gene is responsible for CTX production. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) showed ten proteins in purified phage preparations; however, CTX could not be detected on Western blots using an enzyme-linked immunofluorescence assay.

Base Sequence↗
PubMed1993

Wear of ceramic inlays, their enamel antagonists, and luting cements.

The wear of ceramic inlay materials and antagonist enamel cups was measured in vitro. Per group, six MOD inlays were adhesively cemented in extracted molars. Castable glass ceramic, pressed glass ceramic, and feldspathic porcelain were used as inlay materials. A microfilled and a fine hybrid composite served as luting agents. The restorations were exposed to an in vitro wear test that corresponds to approximately 5 years of clinical service. The wear in the occlusal contact area was quantified during and at the end of the test with a three-dimensional scanner. Final wear measurements on the inlays (mean +/- SD) ranged from 21.8 +/- 8.8 microns for pressed glass ceramic to 59.0 +/- 37.9 microns for castable glass ceramic. The mean wear of the enamel antagonists ranged from 74.6 +/- 32.9 microns for pressed glass ceramic to 153.2 +/- 61.5 microns for feldspathic porcelain. The wear of the luting composites at the end of the test ranged from 4.9 +/- 5.1 microns for microfilled to 12.3 +/- 6.3 microns for fine hybrid.

Aluminum Silicates↗
PubMed1993

Marginal adaptation and fit of adhesive ceramic inlays.

This in vitro study compared the marginal adaptation of CAD/CAM and laboratory-made ceramic inlays before, during and after loading. Six MOD inlay preparations of standardized design with one cervical margin in dentine and the other in enamel were prepared for each inlay type: CAD/CAM fabricated MGC-glass ceramic inlays, CAD/CAM fabricated feldspathic porcelain inlays, laboratory-made glass ceramic inlays and laboratory-made feldspathic porcelain inlays. Appropriate luting composite materials were used. The restored teeth were subjected to occlusal loading, thermal cycling, toothbrush-toothpaste abrasion and chemical degradation in vitro. Marginal adaptation was quantitated along the entire length of the cavosurface margin and along selected sections of the margin using SEM, following in vitro testing corresponding to 0, 0.5, 1.0, 2.7 and 5.0 years of clinical service. In addition, marginal fit of the cemented inlays was evaluated in the SEM. The initial marginal adaptation in enamel was excellent in all groups. After in vitro testing, significant marginal discrepancies were found in all groups. A high percentage of marginal openings was recorded, notably in the cervical portions of the margins in both enamel and dentine.

Ceramics↗
PubMed1993

Periodontal repair or regeneration: structures of different types of new attachment.

The present study details the structural and ultrastructural features of healing events between the regenerated periodontal ligament and the root surface after experimental periodontal disease. Experiments were performed on dogs, and the concept of guided tissue regeneration was tested using resorbable polyurethane membranes. Light microscopy, scanning- and transmission electron microscopy were employed to determine if healing events involve regeneration (ie, process by which the architecture and the function are completely renewed) or periodontal repair (ie, healing of a wound by tissue that does not fully restore the architecture of a part). Regeneration occurred in parts of the roots only if some original cementum remained on the root surface after root planing. Repair was observed if peripheral dentin was removed by root planing as this layer was not reestablished. In areas remote from the base of the defect, new collagen fibrils, synthesized by fibroblasts and oriented perpendicular to the root surface, were spliced with severed ends of Sharpey's fiber bundles of original cementum. If circumpulpal dentin was exposed, intermingling between new fibrils with dentinal matrix fibrils occurred. In areas near the base of the defect, the first event was the formation of a cementoid by a cementoblast monolayer and subsequent formation of intrinsic fibrils oriented parallel to the root surface. Afterwards, the cementoblast monolayer disintegrated and extrinsic fiber bundles became anchored in the new cellular mixed fiber cementum. In these areas, linkage between new cementum and pre-existing tissues always occurred by interfacial intermingling of the fibrils, regardless of whether new attachment occurred at circumpulpal dentin or original cementum.

Animals↗
PubMed1993

Influence of dentinal fluid and stress on marginal adaptation of resin composites.

The influence of dentinal fluid and of a number of stress procedures on the quality of the margins of class V restorations located in both enamel and dentin was quantitatively assessed in vitro with the aid of a scanning electron microscope. The materials tested were GLUMA 2000 experimental, Prisma Universal Bond 3, and Syntac, together with the fine hybrid composites supplied by the respective manufacturers (Pekafill, AP.H, and Tetric). All materials achieved over 95% of "continuous margin" in enamel before and after stressing. In dentin, the initial values, with as well as without dentinal fluid simulation, were situated between 93.2 and 98.2%. With GLUMA 2000 experimental after stressing, a "continuous margin" occurred in only 50.2%, but with Prisma Universal Bond 3 and Syntac, the value was 79.0%. The influence of dentinal fluid simulation was dependent on the dentinal adhesive used. The effects of the various stress procedures were not significantly different.

Body Fluids↗
PubMed1993

[Fluoride gels--local application with a tray or a toothbrush?].

Fluoride gels have been used since the 1960s. Most gels are recommended for use in mouth-trays. An alternative is the application on a toothbrush. The present study compared the fluoride concentration in surface enamel and its acid resistance following the application in a tray or on a toothbrush in vitro. In a first experiment 80 halves of molar crowns were used. In group A 20 were coated with fluoride gel. In group B 20 were brushed with gel. 20 each served as water control. The surface fluoride concentration and acid resistance of all samples were assessed using an acid etch technique. In a second experiment 30 halves of molar crowns were used. 10 were mounted in a plaster socket mimicking a dental arch for which a customized miniplast-tray was made. This tray was loaded with 1 g of gel and applied for 3 min on 3 consecutive days. 10 samples were brushed for 3 min on 3 days using 1 g of gel and 10 served as water control. Enamel that had been fluoridated with gel on a toothbrush showed a superior acid resistance. The fluoride concentration in the outer 20 to 25 microns of enamel was higher after gel application on a toothbrush than after tray application.

Acid Etching, Dental↗
PubMed1993

[Scotchbond from 1983 to 1992. The history of a market setter reflected in the literature. A review of the literature].

In this critical literature review 140 [correction of 136] publications dealing with Scotchbond were chronologically compiled since 1983 when Scotchbond was introduced to the dental market. The publications dealing with dentinal bonding were analyzed. Critical statements were predominant in the in-vivo- as well as in the in-vitro-studies. The literature reviewed for a period of ten years clearly demonstrated that the expectations created by the manufacturer and some initial studies concerning dentinal bonding did not become true. Long before private practitioners realized that Scotchbond didn't live up to the standards promised by the manufacturer, independent scientists had doubted the efficiency of the product. The conflict between market orientated and objective information for the private practitioners becomes obvious in this literature review.

Composite Resins↗