Biomedical subjects

Joachim Klimek

Publications and source records attributed to Joachim Klimek.

8 recordsLinked to original sources

PubMed2006

Retention of KOH-soluble fluoride on enamel and dentine under erosive conditions--A comparison of in vitro and in situ results.

OBJECTIVES: Aim of the study was to investigate the stability of CaF(2)-like precipitates on enamel and dentine under neutral or acidic conditions and to compare in vitro and in situ results. METHODS: Human enamel and dentine specimens were fluoridated (Elmex fluid, 5 min) and subjected to erosive demineralisation (Sprite light: 3/day each; 30 s in vitro, 2 min in situ) or stored under neutral conditions for 4 (in vitro) or 7 (in situ) days. KOH-soluble fluoride was determined using an ion selective electrode. Between the acid attacks, specimens were stored in remineralisation solution (in vitro) or retained in the oral cavity (four volunteers for enamel and dentine each). RESULTS: Initially, high amounts of KOH-soluble fluoride were gained (between 77.9+/-12.3 and 96.0+/-46.4 microg/cm2). Under neutral conditions in vitro, a significant decrease on enamel (16.2+/-5.0 microg/cm2) and dentine (18.6+/-10.5 microg/cm2) was found, which was more severe under acidic conditions (6.3+/-3.0 and 5.1+/-2.1 microg/cm2, respectively). Under in situ conditions, KOH-soluble fluoride was strikingly stable on enamel under neutral (42.3+/-12.6 microg/cm2) as well as under acidic conditions (54.1+/-17.4 microg/cm2). On dentine, the dissolution kinetics of KOH-soluble fluoride was similar to the in vitro conditions, but the loss was less severe (45.3+/-12.9 microg/cm2 under neutral and 8.8+/-6.4 microg/cm2 under acidic conditions). CONCLUSIONS: In vitro, more KOH-soluble fluoride was lost under erosive compared to neutral conditions. The intra-oral environment was considerably protective for CaF2-like precipitates especially on enamel.

Amines↗

PubMed2005

Evaluation of a profilometrical method for monitoring erosive tooth wear.

The in vivo monitoring of erosive wear is difficult because lesions mostly progress relatively slowly and reliable reference points are difficult to obtain. To date, only a few methods for clinical monitoring of erosive loss have been described, which either require extensive equipment or do not provide sufficient sensitivity. The aim of the present study was to evaluate, using study models (epoxy resin material), a procedure that permits the reliable and accurate monitoring of erosive substance loss within acceptable observation periods. The method is the profilometric measurement of erosive tissue loss using acid-resistant markers, which represent both a reference area and a structure for the defined retracing of a given erosive lesion surface. The study model magnified values slightly (2.8%; not significant), the precision was < 4 microm, and the repeatability was good (95% limits of repeatability ranging from -4.7 to 5.2 microm). The estimated detection threshold for erosive loss is 15 microm, which appears to be adequate for monitoring. The method is indicated for special dental care in cases of severe dental erosion (e.g. eating disorders) and for clinical studies.

Dental Enamel↗

PubMed2004

Quantitative analysis of the impact of the organic matrix on the fluoride effect on erosion progression in human dentine using longitudinal microradiography.

After an initial demineralisation, an intensive fluoridation is capable of inhibiting the erosive mineral loss in dentine completely, which might be related to the presence of the exposed organic dentine matrix. Aim of the present study was, therefore, to evaluate whether fluoride is also effective when the organic material is removed. The study was a cyclic de- and remineralisation model over 5 days in vitro. Samples from human coronal dentine were demineralised with citric acid (pH 2.3; 6 x 10 min per day) and intermittently stored in a remineralisation solution. Groups (n = 25 each) were defined as follows: Group 1: erosion only, no fluoridation; Group 2: erosion, alternately fluoridation with toothpaste (NaF; 0.15% F-; 3 x 5 min per day), mouthrinse (Olaflur/SnF2; 0.025 F-; 3 x 5 min per day) and gel (Olaflur/NaF; 1.25% F-; at Days 1 and 3 instead of one toothpaste application); Group 3: erosion and fluoridation as Group 2, organic material was continuously removed with collagenase (from Clostridium Histolyticum type VII, 100 U/ml) added to the remineralisation solution. Mineral content was monitored daily using longitudinal microradiogaphy. After fluoridation in the presence of collagenase, a linear increase in mineral loss (73.3 +/- 17.6 microm at Day 5) was observed, which significantly (P < or = 0.001) exceeded that of the control group (45.9 +/- 14.3 microm at Day 5). After fluoridation in the absence of collagenase, mineral loss ceased after the 2nd day (12.2 +/- 10.2 microm at Day 5) and was significantly lower compared to Groups 1 and 3 (P < or = 0.001). The results indicate that the dentine matrix is essential for the effectiveness of fluoride in dental erosion.

Cariostatic Agents↗

PubMed2002

4.4 Electronic management systems.

The international development and deployment of an electronic modularized dental curriculum is central to the development of an electronic engine to be used for the effective management of dental education. This will ensure continuity in high quality of care across all boundaries, through the continuous updating of its content and linkages to contemporary resources and databases. An electronic engine to be used for the effective management of dental education in a comprehensive dental school/hospital setting is at the core of an international 'virtual' dental education institution. The issue of policy development necessary to ensure consistency, quality and management for an electronic engine is at the very centre of: a) systems management and system databases; b) records of students, patients and personnel; and c) financial records.

Computer Security↗

PubMed2002

Characteristics of tooth wear in relation to different nutritional patterns including contemporary and medieval subjects.

The present study sought to evaluate the characteristics of tooth wear in subjects with an acidic diet in relation to subjects with substantially different nutritional patterns. The evaluation included medieval skulls (group 1, n = 102, abrasive nutrition), study models of individuals living on an acidic diet (group 2, n = 100) and randomly selected subjects (group 3, n = 100, average Western diet). Wear was visually recorded on oral, vestibular and occlusal/incisal surfaces using quantitative and morphological criteria. The mean age was 42.3 +/- 15.3 yr in group 1, 40.9 +/- 11.2 yr in group 2 and 36.7 +/- 11.7 yr in group 3. Group 1 exhibited the most pronounced substance loss, followed by groups 2 and 3. On occlusal surfaces, cupping was common in group 1 followed by group 2, but was rare in group 3. An inverse relation was found for facets. On buccal surfaces, no substance loss was observed in group 1, whereas in group 2, 63% had at least one tooth with a buccal lesion compared to 8% in group 3. The occlusal substance loss observed in subjects exposed to acids may be interpreted as increased abrasion/demastication of acid-softened dental hard tissues. The occurrence of concavities on smooth surfaces appears to be significant for the diagnosis of dental erosion.

Acids↗

PubMedDate not supplied

Surface geometry of three packable and one hybrid composite after finishing.

This study compared the effects of different finishing techniques on the surface of a traditional hybrid composite and three packable composites. Four composites were used in the study (Herculite XRV/Kerr, Definite/Degussa, SureFil/Dentsply and Solitaire/Heraeus-Kulzer). Fifty specimens were made of each material, sized 7 x 7 x 4 mm. Fifteen specimens of each material were subjected to the following finishing procedures: (1) a 30 microm diamond, (2) a 30 microm and a 20 microm diamond and (3) a 30 pm diamond followed by a tungsten carbide finishing bur. As a reference, five specimens of each material were treated by Sof-Lex discs (3M). For quantitative surface evaluation, laser-stylus profilometry was used. Roughness parameters included average roughness (Ra) and profile-length-ratio (LR). Statistical analysis was performed with one- and two-way Anova and Scheffé post-hoc tests. Qualitative surface evaluation in SEM was performed at a tension of 25kV. Significant effects were found with both the composites and the finishing methods with respect to surface roughness (p < 0.001 for Ra and LR). A 30 microm diamond caused the greatest roughness on all composites, with Ra ranging from 2.015-2.079 microm (p<0.001). After finishing using methods 2 and 3, the Solitaire surfaces were significantly smoother (p < 0.001 for LR). The lowest roughness values were achieved after using disks; again, the Solitaire specimens yielded the lowest Ra and LR values (p < 0.001 except for Sure-Fil). With scanning electron microscopy, surface areas with signs of destruction were found after using a 30 microm diamond on Definite specimens.

Analysis of Variance↗

PubMedDate not supplied

Surface geometry of three packable and one hybrid composite after polishing.

This study evaluated the surface quality of four composite materials after polishing with six different polishing techniques. Eighty specimens were made using three packable composites (Definite/Degussa, SureFil/ Dentsply and Solitaire/Heraeus-Kulzer) and one hybrid composite (Herculite XRV/Kerr). Five specimens of each material were polished using flexible Sof-Lex discs. The remaining 75 specimens of each composite were prepared using three finishing protocols: a single 30 microm diamond (n = 25), two finishing diamonds (30/20 microm; n = 25) and a 30 microm diamond followed by a tungsten carbide finishing bur (n = 25). Final polishing of each of the three finishing groups was accomplished with SuperBuff, Diafix-oral, OneGloss, Astropol and HaWe Composite Polishers (n = 5, each). Surface roughness was evaluated quantitatively by laser-stylus profilometry. Average roughness (R(a)) was calculated; statistical analysis of the data was performed with two-way ANOVA and Scheffé post-hoc tests. The polished surfaces were examined qualitatively by SEM. The results showed significant effects on surface roughness from the different composites (p = 0.011) and polishing systems (p < 0.001). After polishing, the Solitaire surfaces (R(a) = 0.72 microm) were smoother than Definite (R(a) = 0.87 microm) and SureFil (R(a) = 0.89 microm) and significantly smoother than Herculite (R(a) = 0.92 microm; p = 0.011). Three of the polishing methods (SuperBuff, Diafix-oral and Astropol) achieved lower R(a)-values than Sof-Lex discs. The polishing quality of the one-step systems SuperBuff and Diafix-oral was strongly affected by the initial finishing protocol.

Aluminum Oxide↗

PubMedDate not supplied

Polishing occlusal surfaces of direct Class II composite restorations in vivo.

This study evaluated the effects of four polishing methods on the occlusal surfaces of direct Class II composite restorations under clinical conditions. Forty premolars and 40 molars were treated with direct Class II restorations using the hybrid composite Herculite XRV (Kerr). After placement of the restorations, all of which were on occlusal surfaces, they were finished with a sequence of 30 microm diamonds and tungsten carbide instruments. Twenty restorations each, consisting of 10 premolars and 10 molars, were polished with one of the four following methods: (1) Diafix-oral (Mueller-Dental), (2) MPS gel (Premier), (3) P 403-W (Dentsply) and (4) Occlubrush (KerrHawe). Selection of the polishing methods followed a randomized protocol. Replicas of the restored teeth were fabricated and the occlusal surfaces were evaluated quantitatively for roughness with the help of profilometry. Qualitative assessment of the surfaces by SEM was done with respect to roundness of contours and surface roughness. The results were analyzed statistically by two-way ANOVA, chi-squared test for crosstables and Kruskal-Wallis test. Analysis of the quantitative data showed that there was no significant effect of the polishing methods on occlusal surface roughness (p>0.05). Localization of the restoration in premolars or molars had no effect on surface roughness (p>0.05). With respect to occlusal relief, SEM examination revealed that the use of the Occlubrush resulted in significantly more edged contours compared to the other polishing methods (p=0.008). Qualitative roughness evaluation showed that there were no significant differences among the four polishing methods (p>0.05).

Adolescent↗