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Biomedical subjects

P Städtler

Publications and source records attributed to P Städtler.

At least 19 recordsLinked to original sources
PubMed1999

Five-year follow-up of internal bleaching.

A 5-year clinical follow-up study was conducted to determine the longevity of originally acceptable results for internal bleaching. The "walking internal bleaching" method is an acceptable technique of lightening discolored anterior teeth to provide an esthetically pleasing match with adjacent teeth. This follow-up study revealed a success rate of 79% for all indications after 5 years. If the indication is limited to one palatal endodontic opening, the total success rate can reach 91%. However, a 98% success rate is common when subjective evaluation of patients is considered. The results clearly indicated that internal bleaching provides long-term success for treatment of discolored nonvital anterior teeth over a period of years and does not have any detrimental effect on dental hard tissue. In ideal cases, if the procedure is performed precisely, the success rate can exceed 90% after five years.

Adolescent↗
PubMed1998

Intrapulpal temperature during preparation with the Er:YAG laser compared to the conventional burr: an in vitro study.

OBJECTIVE: The authors explored whether the preparation with the Er:YAG laser showed a difference in increase of intrapulpal temperature in comparison to the conventional burr. SUMMARY BACKGROUND DATA: The effect of preparation with the Er:YAG laser on the temperature in the pulp is probably the biggest problem in using the laser for preparation of dental hard tissue. METHODS: The effect on the temperature in the pulp was studied on extracted human incisors and canines in vitro in palatinal class I cavities. The temperature during preparation with the Er:YAG laser was compared to that recorded during conventional tactile preparation with a diamond burr. The study was designed so that the pulpal cavity and the measuring probe were kept at a constant temperature of 37 degrees C from the root upward while the crown, which was thermally isolated, was exposed to preparation and cooling agents. RESULTS: During preparation with the laser, there was a temperature drop after a few seconds from 37 degrees C to 25 degrees C to 30 degrees C due to cooling with water and air. Even with trepanation, there was only an increase in temperature in the pulp when the temperature measuring probe was hit directly by the laser beam. With conventional preparation in comparison, even before trepanation there was a rise in temperature to more than 60 degrees C. CONCLUSIONS: The reduction in pain with clinical use of the Er:YAG laser for class V cavities has already been mentioned in publications and could, in addition to the nontactile preparation, be due to the lesser increase in intrapulpal temperature during the laser preparation in comparison to the conventional burr.

Body Temperature↗
PubMed1996

The effect of sodium trimetaphosphate on caries: a 3-year clinical toothpaste trial.

The objective of this study was to assess the anticaries efficacy of a toothpaste containing 3% sodium trimetaphosphate (TMP; test) relative to a toothpaste containing no caries-preventive agent (control). The study was designed as a 3-year double-blind caries incidence study involving about 2,500 subjects aged 11 years at baseline. After a clinical examination, subjects were stratified by sex, presence of supragingival calculus and caries status and randomly assigned to either the control or the test group. Clinical examinations then took place at annual intervals. At baseline and at the final examination bite-wing radiographs were taken of subjects not radiographed within the previous 6 months. The change in caries between baseline and the 3-year examination was calculated as DMFS increments. The results showed a statistically significant difference of 8% between the test and control groups (p < 0.05). In subjects brushing twice daily the difference between the test and control group was 11% (p < 0.01). It is concluded that, when used regularly, a toothpaste containing 3% TMP will be effective against caries.

Analysis of Variance↗
PubMed1995

Splints made of wire and composite: an investigation of lateral tooth mobility in vivo.

In 103 posttraumatic splints, later tooth mobility was measured with Periotest immediately before and after the routine splint removal. The splints were made of composite resin and an 0.017 X 0.025" orthodontic steel wire. 481 teeth were measured. A statistic evaluation revealed that the immobilisation effect did not exceed normal tooth firmness. Fixation to one neighbouring tooth had less effect than fixation to two. Adjacent tooth gaps reduced the effect. Splint extensions had no influence. With the use of the Periotest device, more than 50% of all teeth with a true mobility of 20 Periotest-units or more were detectable as mobile in spite of the fixed splint.

Adolescent↗
PubMed1995

[The stress transmission of prefabricated root canal posts].

Photoelastic stress analyses were done with nine prefabricated endodontic posts under axial and diagonal (26 degrees) burden with 5, 10, 15, 20, 25 kg. Stress presented itself in form of interference fringes, which became visible under polarized light. The tapered, grooved pins (Mooser and Unimetric) caused fringes along the shaft and apical as well. They worked at higher stress like a wedge. Cylindrical pins (Para Post Unity 5, Radix-anchor) showed relative strong fringes predominantly at the top. Cylindrically tapered pins (Tenax, CM, Pivomatic) and a conical pin with flat thread and grooves (Exatec-S) caused a more favourable stress distribution and the fringes at the top were clearly slighter.

Cementation↗
PubMed1995

The relative caries-inhibiting efficacy of amine fluoride and sodium fluoride in compatible dentifrices--results of a consensus conference.

A conference concerning the caries-inhibiting efficacy of dentifrices that contain amine and sodium fluorides compared relevant clinical studies and found that both fluoride compounds contribute to the maintenance of dental health. Because of the differing test conditions, the study results cannot, however, be compared. Thus, there is no definite scientific proof of the superiority of one fluoride compound, and no such proof will exist until dentifrices containing amine fluoride and sodium fluoride are tested in a direct clinical comparison.

Amines↗
PubMed1993

Purification and characterisation of the restriction endonuclease ItaI from Ilyobacter tartaricus recognizing 5'-GC decreases NGC-3'.

ItaI, an isoschizomer of the subclass IIW [Kessler and Manta, Gene 92 (1990) 1-248] restriction endonuclease (ENase), Fnu4HI [Leung et al., Nucleic Acids Res. 6 (1979) 17-25], has been isolated from Ilyobacter tartaricus. The ENase has the five-base palindromic recognition sequence, 5'GC decreases NGC-3'. It cleaves behind the second nucleotide and produces a one-nt 5' overhang.

Deoxyribonucleases, Type II Site-Specific↗
PubMed1993

Structure and function of proteins of the phosphotransferase system and of 6-phospho-beta-glycosidases in gram-positive bacteria.

New information about the proteins of the phosphotransferase system (PTS) and of phosphoglycosidases of homofermentative lactic acid bacteria and related species is presented. Tertiary structures were elucidated from soluble PTS components. They help to understand regulatory processes and PTS function in lactic acid bacteria. A tertiary structure of a membrane-bound enzyme II is still not available, but expression of Gram-positive genes encoding enzymes II can be achieved in Escherichia coli and enables the development of effective isolation procedures which are necessary for crystallization experiments. Considerable progress was made in analysing the functions of structural genes which are in close vicinity of the genes encoding the sugar-specific PTS components, such as the genes encoding the tagatose-6-P pathway and the 6-phospho-beta-glycosidases. These phosphoglycosidases belong to a subfamily of the beta-glycosidase family I among about 300 different glycosidases. The active site nucleophile was recently identified to be Glu 358 in Agrobacterium beta-glucosidase. This corresponds to Glu 375 in staphylococcal and lactococcal 6-phospho-beta-galactosidase. This enzyme is inactivated by mutating Glu 375 to Gln. Diffracting crystals of the lactococcal 6-P-beta-galactosidase allow the elucidation of its tertiary structure which helps to derive the structures for the entire glycosidase family 1. In addition, a fusion protein with 6-phospho-beta-galactosidase and staphylococcal protein A was constructed.

Amino Acid Sequence↗
PubMed1993

Five-year survival rate of fissure sealings and fissure restorations.

Five hundred and thirty-four sealants and fissure restorations were checked up over a period of five years. The survival rate within five to six years amounted to 94.3% and 77.2% in relation to total and partial loss, respectively. It was significantly lower with molars than with premolars. No significant difference was found between sealants and fissure restorations nor with applications in the upper and lower jaws. Sealants and fissure restorations seem to be recommendable for the prevention as well as for conservative treatment of initial defects because more substance of the tooth is preserved than with conventional filling methods.

Adolescent↗
PubMed1992

A 3-year clinical study of a hybrid composite resin as fissure sealant and as restorative material for Class I restorations.

After 3 years, 78.0% of 64 reexamined fissure restorations (extended sealants) and small occlusal restorations were clinically acceptable or excellent, and 21.9% had to be repaired or replaced because they had fractured (6.3%) or were no longer clinically acceptable by some other criterion (15.6%). The conservative preventive resin restoration seems to be an effective treatment for small occlusal defects. Meticulous dental hygiene by the patient and regular examinations by the dentist are mandatory.

Composite Resins↗
PubMed1992

Toothpastes.

It is well known that plaque is the main cause of caries and parodontopathies, which puts the role of toothpastes as an important means of prevention of odontopathies to the foreground. Toothpastes can be more or less oriented towards having a particular effect, such as cleaning, anticaries effect, antimicrobial effect or inhibition of the formation of tartar. Toothpastes contain substances which promote dental health, such as abrasives (silicium dioxide, brushite, calcite, calcite and aragonite, gibbsite etc.), active components (fluorides, triclosan, metal ions, sanguinarine and surface-active substances), substances which motivate the use of toothpaste (sweetening agents, aromatic oil, colours) and components which are necessary for technical reasons, such as moisturizing agents, binders and opacifiers.

Alkaloids↗
PubMed1991

[Caries prevalence, periodontal status, traumatised anterior teeth and sealant in 11-14-year olds in Styria].

The average caries prevalence for first year pupils in secondary schools (Hauptschulen and Gymnasien) was 3.2 DMFT and 5.8 DMFS. The corresponding values for fourth year pupils were 6.4 DMFT and 12.4 DMFS. The proportion of children with at least one extracted first molar was 9.2%. Significant differences were observed between the two schooltypes. The periodontal assessment showed pocket depth greater than 3 mm in at least one molar in 42% of the fourth year children. Only 3-4% of those examined had sealed fissures. Carles prevalence in Styrian children is considerably higher than reported for other countries. It therefore appears necessary to intensify dental health in this age group.

Adolescent↗
PubMed1991

[Cariogenic potential of in-between-meals--results of oral plaque-pH-telemetry].

Using oral plaque-pH-telemetry the cariogenic potential of a sucrose-solution (10%), a sorbitol-solution (10%), of a roll with honey, a roll with jam together with sweetened coffee and the "Milchschnitte" has been examined. All sugar containing products cause a deep pH-drop in dental plaque. The duration of demineralization (time of plaque-pH below 5.5)-amounts to 75 min. after mouthrinsing with sucrose-solution, 80 min. after consuming a half roll with honey, 140 min. after eating a roll with jam and drinking sweetened coffee and 82 min. after consuming a "Milchschnitte". All these products shouldn't be used as in-between-meals or snacks without a consequent oral hygiene afterwards.

Dental Caries↗
PubMed1991

[Preparation of root canals with the Excalibur in comparison with manual instrumentation, Endocursor and Intra-Endokopf].

64 curved root canals of acrylic models were instrumented from two experienced operators with Endocursor, Excalibur, Intra-Endokopf 3LDSY and by manual. A significant influence on the form of the root canal preparation had the factors instrument type, operator and the interferences between operator and instrument. The time of root canal preparation had a significant influence in the middle and coronal third of the root only. The best results are achieved by ideal combination of operator and instrument. With the Excalibur it is possible, to make a sparing and careful instrumentation. The excellent calibration guide is very helpful.

Dental Cavity Preparation↗
PubMed1991

[Chemical degradation of 15 composites--an SEM study].

SEM-micrographs of 15 untreated composites that were laid in 96% ethanol were investigated. The surface of untreated samples show different fissures and cracks. Under the influence of alcohol the fissures become wider, the bond between fillers and unfilled resin enlarges, and the filling particles become prominent or fall out. Fine-grained hybrid composites with an unfilled resin densely compacted with microfillers, are least prone to degradation.

Composite Resins↗