Biomedical subjects

A Welk

Publications and source records attributed to A Welk.

13 recordsLinked to original sources

PubMed2007

The peritoneal explant test for evaluating tissue tolerance to mouthrinses.

The tissue cultures of explants of neonatal rat peritoneum have been demonstrated to be a sensitive test for tissue compatibility with wound antiseptics. The present study investigated the suitability of this method to assess the relative toxicity of mouthrinses to tissue. Mouthrinses containing 0.1% chlorhexidine (Chlorhexamed Fluid 0.1%) (A), 0.3% triclosan (Colgate) (B), essential oil in ethanolic solution (Listerine) (C), and amine/stannous fluoride (Meridol) (D) were tested at use concentration and in dilutions of 10, 1, and 0.1% with exposure times of 1, 10, and 30 min, respectively. The mouthrinses (test) and Ringer's solutions (control) were applied to opened rat peritoneum. After thorough irrigation with Ringer's solution, a piece of peritoneum was removed and 1 x 1 mm explants were cut. The explants were cultivated with a bovine serum culture medium in 24-well plates at 37 degrees C in a CO2 incubator (95% air, 5% CO2). After 10 days, the tissue proliferation for the explants was assessed by a stereo microscope at 10x magnification after ethanol fixing and hemalaun staining. With 24 grafts per test, the proliferation rate was calculated relative to a control, which was run for each mouthrinse and concentration/time combination. Data were analyzed using ANOVA (SPSS 11.0) and post-hoc paired t test. Statistical significance of all correlations was tested by setting the significance level at p < 0.05. At most concentrations, D caused significantly less tissue damage than A or B. There was no difference between C and A or C and B at 100%. However, the toxicity of C was significantly less than A or B at 10, 1, and 0.1%. C and D behaved similarly except for the 10% (30 min) and the 1% (10 min) solutions in which C was significantly less toxic. We concluded that the rat peritoneum explant test was demonstrated to be a sensitive test to assess the relative toxicity of mouthrinses to tissue.

Amines↗

PubMed2006

German dental faculty attitudes towards computer-assisted simulation systems correlated with personal and professional profiles.

BACKGROUND: Computer technology is increasingly used in practical training at universities. However, in spite of their potential, computer-assisted simulation (CAS) systems still appear to be underutilised. OBJECTIVES: To investigate the practical usage of CAS/computer-assisted learning (CAL) systems, the familiarity and level of use of CAS systems, as well as the acceptance of approved learning content and English as the language of instruction in CAS/CAL systems. METHODS: A survey was conducted in the Departments of Conservative Dentistry and Prosthetic Dentistry of all 32 dental schools in Germany. Besides investigating the usefulness of, familiarity with and level of current usage of CAS systems, the questionnaire also contained questions regarding each respondent's gender, age, academic rank, experience in academia and computer skills, all of which correlated with the responses. RESULTS: The response rate was 90% (112 out of 125). The use of CAS/CAL systems was considered 'partly' to 'very' useful for evaluating the acquisition of knowledge (83.9%), qualitative issues (73.2%) and processes (72.3%) of dental preparation exercises and complex treatment strategies. However, only about half the respondents reported that they knew of, and even fewer used, the following systems in preclinical or clinical training: EDUnet (KaVo, Germany) (46.3%/0.9 %), PREPassistant (KaVo, Germany) (50%/0.9%), or the DentSim system (DenX, Israel) (52.8%/1.9%). The virtual simulation system VRDTS-CP (Novint, USA), used by none of the respondents, was known to only 16.5%. Responders agreed at least partly to accept approved learning content (74.9%) and English as the language of instruction (82.1%) as the standards for CAS systems. CONCLUSION: The survey indicates a distinct discrepancy between a generally positive attitude towards the usefulness of computer technology for dental education, the level of familiarity with current computer systems and their actual use. However, two prerequisites for ultimately decreasing the cost and increasing the usage of CAS systems--the acceptance of approved learning content and English as the language of instruction in CAS systems--seem to be generally accepted by respondents.

Adult↗

PubMed2006

Computer-assisted learning and simulation systems in dentistry--a challenge to society.

INTRODUCTION: Computer technology is increasingly used in practical training at universities. However, in spite of their potential, computer-assisted learning (CAL) and computer-assisted simulation (CAS) systems still appear to be underutilized in dental education. MATERIALS AND METHODS: Advantages, challenges, problems, and solutions of computer-assisted learning and simulation in dentistry are discussed by means of MEDLINE, open Internet platform searches, and key results of a study among German dental schools. RESULTS: The advantages of computer-assisted learning are seen for example in self-paced and self-directed learning and increased motivation. It is useful for both objective theoretical and practical tests and for training students to handle complex cases. CAL can lead to more structured learning and can support training in evidence-based decision-making. The reasons for the still relatively rare implementation of CAL/CAS systems in dental education include an inability to finance, lack of studies of CAL/CAS, and too much effort required to integrate CAL/CAS systems into the curriculum. CONCLUSION: To overcome the reasons for the relative low degree of computer technology use, we should strive for multicenter research and development projects monitored by the appropriate national and international scientific societies, so that the potential of computer technology can be fully realized in graduate, postgraduate, and continuing dental education.

Computer Simulation↗

PubMed2005

The effect of a polyhexamethylene biguanide mouthrinse compared with a triclosan rinse and a chlorhexidine rinse on bacterial counts and 4-day plaque re-growth.

OBJECTIVES: For various clinical applications, polyhexamethylene biguanide hydrochloride (PHMB) has been used for many years as an antiseptic in medicine. Recently, a 0.04% and a 0.12% PHMB mouthwash were shown to inhibit plaque re-growth and to reduce oral bacterial counts. In this study, a 0.2% PHMB mouthrinse (A) was compared with a positive control 0.12% aqueous chlorhexidine solution (B), a commercially available 0.3% triclosan/2.0% polyvinyl methyl ether maleic acid copolymer mouthrinse (Colgate Total Plax) (C), and a negative control placebo rinse (10% ethanol, flavour) (D). MATERIALS AND METHODS: The controlled clinical study was a double blind, randomized, four replicate cross - over design. Plaque re-growth was assessed with the Turesky et al. (1970) modification of the Quigley & Hein (1962) plaque index. The antibacterial effect was assessed by taking bacterial counts on the tooth surface (smears from the buccal surface of 16/26) and mucosa (smears from the buccal mucosa in opposite of area 16/26) after the professional prophylaxis and after the first rinse with the preparations on day 1 and prior to the clinical examination on day 5. Sixteen volunteers participated and, on day 1 of each study period were rendered plaque-free, ceased toothcleaning, and rinsed twice daily with the allocated mouthrinse. On day 5, plaque was scored and smears were collected according to the protocol. A 10-day wash-out period was carried out between each rinse evaluation. Data were analysed using ancova with Bonferroni HSD adjustment for multiple comparisons (colony forming units per sample) with a significance level alpha=0.05. RESULTS: The 0.2% PHMB mouthrinse (A) was significantly better at inhibiting plaque than the placebo (D), but significant less effective than the 0.12% aqueous chlorhexidine solution (B). There is no significant difference between A and the 0.3% triclosan/2.0% copolymer mouthrinse (C). Bacterial count reductions (tooth surface and mucosa) with PHMB (A) were significantly greater compared with the placebo (D) and triclosan (C), but significantly lower compared with chlorhexidine (B) (tooth surface) and equally effective compared with chlorhexidine (B) (mucosa). CONCLUSION: Consistent with previous studies, a PHMB mouthrinse was shown to inhibit plaque re-growth and to reduce oral bacterial counts, indicating that PHMB could be an alternative to established mouthrinses in preventive applications.

Adult↗

PubMed2005

German dental faculty attitudes towards computer-assisted learning and their correlation with personal and professional profiles.

BACKGROUND: Compared with its potential, computer technology use is still lacking in medical/dental education. OBJECTIVES: To investigate the primary advantages of computer-assisted learning (CAL) systems in German dental education, as well as the reasons for their relatively low degree of use correlated with personal and professional profiles of respondents. METHOD: A questionnaire was mailed to heads in the departments of conservative dentistry and prosthetic dentistry in all dental schools in Germany. Besides investigating the advantages and barriers to the use of computer technology, the questionnaire also contained questions regarding each respondent's gender, age, academic rank, experience in academia and computer skills. RESULTS: The response rate to the questionnaire was 90% (112 of 125). The results indicated a distinct discrepancy between the desire for and actual occurrence of lectures, seminars, etc. to instruct students in ways to search for and acquire knowledge, especially using computer technology. The highest-ranked advantages of CAL systems in order, as seen by respondents, were the possibilities for individual learning, increased motivation, and both objective theoretical tests and practical tests. The highest-ranked reasons for the low degree of usage of CAL systems in order were the inability to finance, followed equally by a lack of studies of CAL and poor cost-advantage ratio, and too much effort required to integrate CAL into the curriculum. Moreover, the higher the computer skills of the respondents, the more they noted insufficient quality of CAL systems (r = 0.200, P = 0.035) and content differences from their own dental faculty's expert opinions (r = 0.228, P = 0.016) as reasons for low use. CONCLUSION: The correlations of the attitudes towards CAL with the personal and professional profiles showed not only statistical significant reinforcements of, but also interesting deviations from, the average responses.

Adult↗

PubMed2004

DentSim - a future teaching option for dentists.

Apart from a requirement to acquire more and more academic knowledge, during their training, dental students need to acquire a full range of highly precise manual and technical skills, including excellent hand/eye coordination, to enable them to visualize and understand how to prepare cavities, prior to placing restorations. Furthermore, unlike medical students, dental students are in the position of administering treatment to patients very early in their training. The increasing academic workload means that these skills have to be mastered in a short space of time. This you will gain in the future only through the use of effective methods of the educations - for example by the use of the computer-assisted dental simulators (DentSim/DenX), which serves the visual-, audio- and practical learning channel simultaneously. Unlike the conventional phantom heads, the DentSim-unit has the following advantages - the acquisition of knowledge takes place in a multimedia learning environment with a high audio-visual content and degree of interaction and complexity, - problem-oriented learning takes place through clinically relevant work, - individual students can work to personalized programs through the digital tutor function, - two-dimensional knowledge is transferred into three-dimensional spatial work, - three-dimensional preparations can be easily analysed by two-dimensional error analysis, - all preparation exercises are recorded for error and effectiveness analysis. Apart from student training, the computer-assisted simulators can also be used for the evaluation of the effectiveness or the quality control of various teaching methods in the context of Evidence Based Dental Education.

Computer Simulation↗

PubMed2002

The effect of a polyhexamethylene biguanide mouthrinse compared to an essential oil rinse and a chlorhexidine rinse on bacterial counts and 4-day plaque regrowth.

OBJECTIVES: For various clinical applications, polyhexamethylene biguanide hydrochloride (PHMB) has been used for many years as an antiseptic in medicine. Recently, a 0.04% PHMB mouthwash was shown to inhibit plaque regrowth and to reduce oral bacterial counts. In this study, a 0.12% PHMB mouthrinse (A) was compared with a negative control placebo rinse (10% ethanol, flavour) (B), a positive control 0.12% chlorhexidine rinse (C), and a commercially available mouthrinse containing essential oils (Listerine) (D). MATERIALS AND METHODS: The study was a double-blind, randomised 4-replicate 4 x 4 Latin square cross-over design in which plaque regrowth was measured. The in vivo antibacterial effect was assessed by taking bacterial counts from the tooth surface and mucosa 4 h after the first rinse with the preparations on day 1 and prior to the clinical examination on day 5. 16 volunteers participated and, on day 1 of each study period, were rendered plaque-free, ceased toothcleaning, and rinsed 2x daily with the allocated mouthrinse. On day 5, plaque was scored and smears were collected according to the protocol. Washout periods were 9 days. Data were analysed using ANOVA with Bonferroni HSD adjustment for multiple comparisons (significance level alpha=0.05). RESULTS: The 0.12% PHMB mouthrinse (A) was significantly more effective in inhibiting plaque than the placebo (B) but no significant differences could be observed between A and 0.12% chlorhexidine (C), or between A and Listerine (D). Bacterial count reductions on the tooth surface with PHMB (A) were significantly greater compared to the placebo (B) after 4 h and significantly greater compared to B and D after 5 days. Chlorhexidine (C) was more effective than A after 5 days. On the mucosa, chlorhexidine (C) was significantly more effective in reducing bacterial counts than the other 3 treatments at both time points investigated. PHMB (A) was significantly more effective in reducing bacterial counts than the placebo (B) after 4 h and after 5 days, and than D after 4 h. CONCLUSION: Consistent with a previous study, a PHMB mouthrinse was shown to inhibit plaque recolonisation and to reduce oral bacterial counts, indicating that PHMB may find applications in the prevention of plaque-associated diseases.

Adult↗

PubMed2001

Effect of a polyhexamethylene biguanide mouthrinse on bacterial counts and plaque.

OBJECTIVES: For various clinical applications, polyhexamethylene biguanide (PHMB) has been used for many years as an antiseptic in medicine. Little is known, however, of its antibacterial activity in the oral cavity and its ability to inhibit plaque formation. In this study, a 0.04% PHMB mouthrinse (A) was compared with a negative control placebo rinse (10% ethanol, flavour) (B) and 2 positive control chlorhexidine rinses, one of which was a 0.12% aqueous solution (C) and the other a commercially available mouthrinse (Skinsept mucosa) diluted to a chlorhexidine concentration of 0.12% (D). MATERIAL AND METHODS: The study was a double-blind, randomised 4-replicate 4 x 4 Latin square cross-over design. Plaque regrowth was assessed with the Turesky et al. modification of the Quigley and Hein plaque index. The in vivo antibacterial effect was assessed by taking bacterial counts from the tooth surface (smears from the lingual surface of 16) and mucosa (smears from the buccal mucosa) 4 h after the 1st rinse with the preparations on day 1 and prior to the clinical examination on day 5. 16 volunteers participated, and on day 1 of each study period were rendered plaque-free, ceased toothcleaning, and rinsed 2x daily with the allocated mouthrinse. On day 5, plaque was scored and smears were collected according to the protocol. Washout periods were 9 days. Data were analysed using ANOVA with Tukey HSD adjustment for multiple comparisons (significance level alpha=0.05). RESULTS: Mouthrinses A, C, and D were significantly more effective in inhibiting plaque than the placebo (B). Mouthrinse C was significantly better than mouthrinses A and D, while mouthrinses D and A were equally effective in inhibiting plaque. Bacterial count reductions on the tooth surface with mouthrinse C were significantly greater compared to mouthrinse A and the placebo (B). The reduction of bacterial counts on the mucosa with C was significantly greater than with A and B after 4 h and significantly greater than with A, B and D after 5 days. Mouthrinse A reduced bacteria on the mucosa significantly more effectively than the placebo (B) after 4 h and 5 days, while mouthrinse D was more effective than the placebo (B) after 4 h. CONCLUSION: The results indicate that a 0.04% PHMB mouthwash inhibits plaque regrowth and reduces oral bacterial counts, and may be used in preventive applications in the oral cavity.

Adult↗

PubMed2001

The influence of surface configuration on the retention of posts designed for use with a cast-on technique.

OBJECTIVES: The combination of an individually cast core and a prefabricated metal post is one of the many techniques to restore endodontically treated teeth. The surface characteristics of commercially available posts vary considerably and likely influence retention. In this study, the surface configuration of 11 castable prefabricated post systems and their retention at the post-cement interface were investigated. METHOD AND MATERIALS: Scanning electron microscopic photos were made to assess surfaces of the posts. Etchant residues or applied surface layers were also analyzed with an electron beam microprobe. For the retention measurements, 6 posts from each system were cemented in artificial root canals with a zinc phosphate cement. Retention was measured on a universal testing machine. RESULTS: Analysis of variance and the Ryan-Einot-Gabriel-Welsch F test revealed significant differences in retention between posts; these differences were related to the microstructure of the surfaces of the posts. In general, the coarser the surfaces, the better the retention. Gold plating of the etched surface for one manufacturer resulted in less retention compared to posts of the same type and size that were not plated. CONCLUSION: The surface configuration of a post could be an important factor when selecting a prefabricated post system.

Acid Etching, Dental↗

PubMed2000

Resolution of interdental inflammation with 2 different modes of plaque control.

BACKGROUND, AIMS: The aim of the study was to assess the effect on existing plaque and gingivitis of an oral hygiene regimen which utilizes triclosan/copolymer and to compare it with a regimen which uses interdental cleaning devices to control the interdental inflammation. METHOD: For this investigation, 39 subjects were recruited. They were examined for plaque and gingivitis using the criteria of Turesky modification of the Quigley-Hein index and the papillary bleeding index. Plaque and gingivitis were only scored interdentally. Following the baseline examination, the subjects were randomly assigned into 2 groups. The control group used a dentifrice identical to the test dentifrice but without triclosan/copolymer; subjects in this group were taught to brush their teeth with the modified Bass technique and were instructed to additionally use appropriate interdental cleaning devices. The test group used a dentifrice containing triclosan/copolymer (Colgate Total). They were not instructed to use interdental cleaning devices. RESULTS: Both groups were re-examined after 4 weeks, and 4 and 7 months. In both groups, plaque and gingivitis levels were modestly reduced, more pronounced in the anterior and less in the posterior teeth. CONCLUSIONS: This investigation demonstrated that a dentifrice containing triclosan in combination with a copolymer can reduce plaque and gingival inflammation to levels comparable to regular interdental cleaning.

Adult↗

PubMed2000

Caries prevention with chlorhexidine-thymol varnish in high risk schoolchildren.

In a prospective, randomised and blinded cohort study, the acceptance and effectiveness of a 3-monthly chlorhexidine-thymol varnish application was assessed in 8- to 10-yr-old children (n=29) with high caries incidence after brushing with a 1.23% fluoride gel. The children of the control group (n=25) brushed with a fluoride gel only. The standardised interview showed good acceptance of the varnish applications in spite of the bitter taste. Caries incidence in one year was 1.2 DMFS (SD 1.5, median 1; 95% confidence interval 0-1) for the test group and 2.1 DMFS (SD 2.3, median 2; 95% confidence interval 0-3) for the control group. Due to a slightly lower reduction in caries incidence (42.3%) than in other studies and a higher standard deviation than in unselected study groups, the power of the present study was not high enough to prove this difference in caries incidence to be statistically significant in the Mann-Whitney test (P=0.11). This was also found for the difference of 0.4 initial lesions. The distribution patterns of caries incidence for tooth groups (70% in the first permanent molar) and surfaces (58% on occlusal surfaces) did not differ between the test and the control group. The reductions of caries incidence which have been found in highly caries active children of the present study should be evaluated further with a larger study sample.

Anti-Infective Agents, Local↗

PubMed1999

Morphometrical examinations of the mandibular ramus for the indication of lag screw osteosynthesis described by Eckelt in mandibular condylar fractures.

For several years, lag screw osteosynthesis as described by ECKELT has been used for the surgical treatment of condylar fractures with predominantly positive results. However anatomical variations occasionally do not permit the use of the lag screw. The aim of the present study was to re-examine the anatomical requirements for using ECKELT's lag screw osteosynthesis. Based on a detailed structural analysis of 140 isolated cadaver rami mandibulae, it can be seen that they principally meet the anatomical requirements for the treatment of mandibular condylar fractures with lag screw osteosynthesis using 2.0 mm diameter screws. Rare, extreme anatomical variants emphasize the need for a stricter preoperative determination of the indications. Using spiral computerized tomography, it is possible to exactly assess preoperatively the existing anatomical situation of the ascending mandibular ramus on the planned frontal plane of the lag screw.

Bone Screws↗

PubMedDate not supplied

Responder and nonresponder analysis for a caries prevention program.

To be able to generalize studies, it is important to know whether responders and nonresponders differ significantly. These data are usually not available. To assess whether responders and nonresponders differed significantly, 319 first and second graders in Greifswald, Germany took part in a compulsory dental school examination. Their parents completed a questionnaire on oral health topics and were asked to decide about their children's participation in a school-based caries prevention program plus anonymous scientific evaluation. The 91 children who were not allowed to participate (nonresponders) were older (mean 8.5 years) than the 228 responders (mean 8.1 years; p < 0.001), mostly because of a few older children having repeated a grade. In an age-adjusted analysis, nonresponders exhibited in 21 of 30 indices of higher caries and plaque values, less preventive measures and a lower rate of participation. The difference in caries in the permanent dentition and fluorosis reached statistical significance. This study suggests that nonresponders to caries prevention programs might comply less with preventive measures and exhibit poorer oral health than responders: a result which has to be taken into account in research and prevention programs in the community.

Age Factors↗