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Biomedical subjects

Thomas Imfeld

Publications and source records attributed to Thomas Imfeld.

13 recordsLinked to original sources
PubMed2006

Chlorhexidine-containing chewing gum. Clinical documentation.

A clinical documentation on chlorhexidine containing chewing gum is presented on the occasion of the launch of CHewX, a chewing gum containing 5 mg of chlorhexidine diacetate in Switzerland. Following an overview on functional chewing gum, the mechanism of action of chlorhexidine (CHX), its toxicity and safety are summarized and a review of clinical studies performed with CHX-containing chewing gum given. Indication, dosage, precautions and benefits of CHX chewing gum are described.

Adult↗
PubMed2006

[In vitro tests of internal tooth whitening agents on colored solutions do not replace tests on teeth].

Two in vitro tests for the assessment of whitening agents were evaluated. A simple, reproducible and cost-effective model using coloured solutions was compared to a tooth model. The following bleaching agents were investigated: 1) Sodium perborate tetrahydrate/30% H2O2, 2) sodium perborate tetrahydrate/3% H2O2, 3) thermocatalytic procedure with 30% H2O2 and 4) Opal-escence Endo. In the model using coloured solutions, the light absorption of the solutions was assessed one and 24 hours after application of the whitening agents. In discoloured teeth, whitening agents were placed in a simulated access cavity. In groups 1, 2, and 4, the agents were left in the cavity for three days, whereas in group 3 the substance was applied three times for 30 seconds. Bleaching processes were repeated three times. All bleaching agents proved effective in the model with coloured solutions, as well as in the tooth model. The effect was most pronounced after the first bleaching step. The results showed, however, that the simplified experiment with coloured solutions cannot replace the tooth model.

Analysis of Variance↗
PubMed2005

[Eating disorders (I)--medical and psychiatric aspects].

Adolescent, predominantly female patients suffering from eating disorders usually reveal characteristic personality traits which should be taken into account during the treatment of such cases. Some patients deny their illness, others again feel ashamed of it. At any rate, we ought to respect the patients' integrity and their sense of self-worth. Such disorders tend to result from the stress of being unable to cope with the multiple demands made by the biological and social changes of the patients' development into full maturity. Additional predisposing factors should be noted. Eating disorders are often accompanied by specific psychic and somatic symptoms in terms of comorbidity. These symptoms have to be anamnestically accounted for since they may later result in oral symptoms. A considerable number of these patients suffering from eating disorders either do not completely recover or else tend to relapse.

Adolescent↗
PubMed2005

[Eating disorders (II)--dental aspects].

Patients suffering from eating disorders exhibit oral symptoms indicative to the otherwise concealed illness. The most striking features are the intrinsic erosions due to the regular surreptitious vomiting. They occur in very typical locations within the dental arches and have been termed "perimolysis". Dental professionals are often the first to discover and diagnose eating disorders by detecting perimolysis and consequently face the difficult task to motivate the patients--who often deny their illness--to seek psychiatric help and dental care. Such motivation must be done while respecting the patients' integrity and sense of self-worth. The primary goal of dental care is to preserve the remaining teeth and to prevent further erosive loss of dental hard tissue. The key elements of a dental preventive programme based on pathophysiologic grounds are to enhance local defence mechanisms, to offer chemical and mechanical protection and to diminish abrasive and erosive challenges. Dental restorative therapy must be part of a combined medical and dental treatment plan and should not be started before the eating disorder has been treated and the patients are considered to have stable prognosis. In view of the young age of the patients, the large extension of the erosive lesions and in order to avoid endodontological treatment of mostly sound pulps, non-invasive restorative concepts using adhesive technology should be preferably used. Prophylactic measures and restorative treatment are covered by health insurance (KGV; KLV 18c, 7) if the patients undergo psychiatric or similar adequate treatment.

Adolescent↗
PubMed2004

Influence of drinking method on tooth-surface pH in relation to dental erosion.

The aim of this investigation was to study the intraoral pH response on tooth surfaces in relation to dental erosion during and after drinking a sugar-free cola-type soft drink. Six different methods of drinking were tested in a randomized order: holding; short-sipping; long-sipping; gulping; nipping; and sucking. Two methods of pH measurement were used in two series of individuals. In the first series, pH was measured by using the microtouch method in 12 healthy adults at three dental erosion-prone sites: 11 palatally; 11 buccally; and at the mesiobuccal cusp tip of 16. In the second series, pH was measured by using the telemetric method in 6 healthy individuals, producing continuous recordings of pH by means of a glass electrode in a specified approximal area. The two series showed similar results, although the telemetric method generally recorded larger pH falls. Holding the drink in the mouth before swallowing led to the most pronounced pH drop, followed by the long-sipping method. Gulping resulted in only a small decrease of pH. No differences among the three intraoral sites were found when analyzed by using the microtouch method. The conclusion from this study is that the drinking method strongly affects tooth-surface pH and thereby the risk for dental erosion. It therefore seems appropriate to include advice on the method of drinking in dietary counseling related to dental erosion.

Adolescent↗
PubMed2004

Penetration of a bonding agent into De- and remineralized enamel in vitro.

PURPOSE: To evaluate bonding penetration into different enamel substrates. MATERIALS AND METHODS: Ten extracted human molars were mesiodistally sectioned. Buccal and lingual enamel surfaces were divided into four equal areas using sticky wax. The central two areas of each tooth (n = 20) were demineralized for 12 weeks using an acidic gel (pH 4.8). The lateral areas served as controls. After demineralization, ten specimens were remineralized in a saliva substitute for three weeks. An amine fluoride solution (Elmex Fluid) was applied on one half of each specimen before acid etching. After etching for 120 s, an enamel-bonding agent (Heliobond) containing 0.1% rhodamine was applied onto test and control areas, and was light cured for 60 s. Subsequently, the specimens were sectioned and tag length was determined using a confocal laser scanning microscope (CLSM). Results were statistically compared with ANOVA followed by Scheffe's and Bonferroni/Dunn post hoc tests. RESULTS: With a mean penetration depth of 68 +/- 22 microm, tags in demineralized enamel were significantly longer than in other groups (p < or = 0.01). Penetration decreased significantly in remineralized areas or when fluoride was used (p < or = 0.01), but was still significantly deeper than in control sites (p < or = 0.01). CONCLUSION: Penetration of an unfilled resin into enamel was considerably influenced by the degree of dental hard tissue mineralization. Penetration was increased in demineralized enamel; however, remineralized enamel also allowed good penetration of the bonding agent.

Acid Etching, Dental↗
PubMed2003

[Caries prevalence among students in 16 Zurich districts in the years 1992 to 2000].

Standardized dental examinations of schoolchildren were regularly carried out since 1964 in 16 rural communities of the Canton of Zurich. In 1964, there were no 14-year-old schoolchildren free from caries; in the Nineties about half of the 14-year-olds had a caries-free permanent dentition (DMFT = 0). From the year 1992 to 2000, the caries prevalence (DMFT) of 14-year-olds decreased once again, by 31%. The pit and fissure caries prevalence (DFS) of 12- and 14-year-olds decreased by 28% and 37%, respectively. In 2000, the mean DMFT-value of the 12- and 14-year-old schoolchildren was 0.90 and 1.27 respectively. In 1964, only few 7-year-old schoolchildren were caries-free; in the Nineties about half of the 7-year-olds had a primary dentition without caries. From the year 1992 to 2000, caries prevalence (dmft) in 7-, 8- and 9-year-olds increased by 64%, 22% and 31%. In 2000, the mean dmft-value of all 7-year-old schoolchildren was 2.45. The Swiss schoolchildren had 1.79 dmft; the schoolchildren from former Yugoslavia and from Albania had 6.89 dmft and those of other nations had 3.37 dmft. Possible reasons for the continuous caries decrease in the permanent dentition and the increase in the primary dentition are discussed. Additional measures in order to improve the situation in the primary dentition are proposed.

Adolescent↗
PubMed2003

[An in vitro model for the simulation of approximal wear].

Several methods have been developed to evaluate attritional wear of restorative materials. A distinction was made between attritional wear in occlusal contact areas (OCA) and wear in contact-free occlusal areas (CFOA). Only limited data dealing with approximal wear in vitro are available. Using a new configuration of the computer-controlled masticator, approximal wear of two composites (P-50, 3M and Tetric Ceram, Ivoclar-Vivadent) was assessed in a two-body wear test after thermo-mechanical loading. Wear was quantified using a profilometer. In addition, micromorphology was assessed by SEM. Wear showed a non-linear pattern, which was comparable to occlusal abrasion. After the first loading cycle, wear increased significantly (p < or = 0.05), and subsequently decreased. After a 5-year-equivalent, the mean substance loss for composite specimens was 20.3 +/- 15.6 microns for P-50 und 17.5 +/- 3.1 microns for Tetric Ceram. Approximal wear between enamel surfaces was 3.9 +/- 4.3 microns. In another experiment, the influence of the approximal wear on an enamel bonding agent was assessed. After thermo-mechanical loading, specimens were immersed in a demineralisation gel. The protective potential of the sealant was assessed under a polarized light microscope. The results suggested that partial sealant loss could lead to caries-like demineralisation in the affected areas.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2003

[Caries prevalence among students in the city of Winterthur: comparison with the city of Zurich and 16 communities in the canton of Zurich].

The aim of the present survey was to assess the caries prevalence in schoolchildren of the city of Winterthur in the year 2002. A simple random sample of 1000 schoolchildren was drawn. 65% of the children participated in the standardized investigation. The mean DMFT-value (permanent dentition) in 12-year-olds was 1.0 and was on a low level in a European comparison. The mean dmft-value (deciduous dentition) in 7-year-olds was 2.0. From 1971 to 2002, DMFT-values decreased by about 80% in Winterthur. The dmft-values decreased by about 60%. The splitting by nationality revealed a high caries prevalence in schoolchildren from the former Yugoslavia and Albania. A multivariate analysis showed no significant differences in caries prevalence between the schoolchildren of the city of Winterthur and other communities of the canton of Zurich.

Adolescent↗
PubMed2002

Advances in abrasive technology--prophylaxis pastes.

A newly developed prophylaxis paste that contains perlite as an abrasive medium was compared to conventional prophylaxis pastes with regard to relative dentin and enamel abrasion, cleaning ability, and polishing power. Rubber cups and nylon brushes were used as paste carriers. Water, flour of pumice, and a dentin polishing paste served as controls. The Prophylaxis Paste Index was created to assess the clinical potential of the various prophylaxis pastes more accurately. The index was computed for dentin as cleaning ability divided by relative dentin abrasion x surface roughness (in Ra) x 10, and for enamel as cleaning ability divided by relative enamel abrasion x surface abrasion (in Ra). On dentin and enamel, the perlite-based prophylaxis paste consistently yielded low relative dentin and enamel abrasion values, a good cleaning ability, and low surface roughness scores with both rubber cups and nylon brushes. Of all tested prophylaxis pastes, the perlite-based prophylaxis paste excelled in the Prophylaxis Paste Index on dentin and enamel and with both rubber cup and nylon brush applications. Therefore, a perlite-containing prophylaxis paste may have broad professional therapeutic indications and may be used universally as a single paste to clean and polish both dentin and enamel.

Aluminum Oxide↗
PubMed2002

[In vitro evaluation of the mechanical effects of sensitive toothpastes of the Swiss market].

"Sensitive pastes" are advertised for use by patients suffering from dentin hypersensitivity. Their market share is growing. Their potential of adverse mechanical side effects on dentin are consequently of concern. The aim of this study was to assess the cleaning efficiency, the relative dentin abrasion and the surface roughness induced by ten sensitive toothpastes of the Swiss market. Cleaning efficiency was assessed planimetrically, the relative dentin abrasion was measured using a radio tracer method and the surface roughness was established using a surface scanning method. Four out of the ten tested sensitive toothpastes produced only low abrasion and surface roughening on dentin, and are consequently suitable for the use by patients with dentin hypersensitivity. The remaining six pastes are too aggressive to warrant unlimited use on exposed dentin surfaces. The pain relieving effect of active ingredients of the toothpastes was not assessed.

Dentin Sensitivity↗
PubMed2002

[Dental health of adults in the Zurich Canton].

In 1992 and 1999, dental health in 20- to 79-year-old adults from the canton of Zurich was assessed with a standardized method (WHO). The aim was to establish the current state and changes of dental health. Roughly half of the 852 approached adults selected by chance did take part. In 1992 and 1999, the mean number of unfilled, decayed teeth (DT) was on a low level in all age classes (0.2 to 1.8 depending on age class and examination year). The number of missing teeth (MT) in older adults (60-79) was on a high level (8.8 to 13.4). The number of filled teeth (FT) was highest (14.8 to 16.2) in middle-aged adults (40-59). Total loss of teeth was found only in older adults (60-79). Lack of a "functional" own dentition (5 teeth present in each quadrant) was found in roughly half of the 60- to 69-year-olds and two thirds of the 70- to 79-year-olds. In 1999, the state of the roots and loss of attachment was assessed. Wedge-shaped defects were found in more than half of the middle-aged adults (40-59). Carious roots were found in more than half of the 70- to 79-year-olds. Nearly half of the 70- to 79-year-old participants showed "severe" loss of attachment (> or = 6 mm). In the short period from 1992 to 1999, a significant decrease of 3.7 DMFT was found in 20- to 49-year-old adults. The decrease of 0.9 MT and 2.1 FT means also a decrease in treatment need in this age segment. In contrast, in the 50- to 79-year-olds no change in dental health could be established.

Adult↗