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Biomedical subjects

H J Staehle

Publications and source records attributed to H J Staehle.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Illnesses caused by amalgam?].

BACKGROUND: As side effects of dental amalgam have been mentioned allergy, oral lichen, electro-galvanism, amalgam tattoos of gingiva or oral mucosa, and undesirable esthetics. Patients with amalgam restorations show increased mercury levels in different body fluids compared to amalgam-free controls. An intoxication due to dental amalgam fillings, however, is not to be expected-despite equivocal statements in the literature. SCIENTIFIC RESULTS: In contrast, recent studies revealed that dental amalgam contributes to mercury exposure less than assumed few years ago. Therefore, amalgam will stay an option as a restorative material in future. The removal of intact amalgam fillings in the intention of "detoxification" is not science-based. CONCLUSION: Successful caries prevention (e.g. due to the widespread use of fluoride) and the further development of esthetic restorative materials based on composite resins will limit the utilisation of amalgam. Thus, alternative materials have not been shown to have a lower rate of side effects (e.g. allergy) compared to amalgam.

Dental Amalgam↗
PubMed1998

Validity of radiographic measurement of interproximal bone loss.

The aim of the present study was to compare radiographic assessment of interproximal bone loss using a loupe with a 0.1 mm calibrated grid and a computer-assisted analysis system (LMSRT). In 35 patients suffering from untreated advanced periodontal disease, 62 standardized radiographs were taken presurgically. The horizontal and vertical angulation difference of the central beam from the orthoradial projection was calculated for each radiograph. At the time of surgery, for 115 interproximal defects, the distances from the cementoenamel junction (CEJ) to alveolar crest (AC), and CEJ to bottom of the bony defect (BD) were measured. In all radiographs, the linear distances CEJ to AC, and CEJ to BD were assessed using a loupe and LMSRT. Comparison between radiographic and intrasurgical assessments was performed using paired t-tests. A stepwise multiple linear regression analysis was used to evaluate factors that influence the discrepancy between radiographic and intrasurgical measurements. Both analyzing techniques underestimated interproximal bone loss as compared with intrasurgical measurements (CEJ-AC: loupe: 0.86 +/- 1.84 mm [p < 0.001]; LMSRT: 0.58 +/- 1.86 mm [p < 0.005]; CEJ-BD: loupe: 1.22 +/- 2.33 mm [p < 0.001]; LMSRT: 0.80 +/- 2.09 mm [p < 0.001]). LMSRT underestimated interproximal bone loss significantly less than the loupe (p < 0.001). The difference between LMSRT and intrasurgical assessments was modulated by the factors of vertical and horizontal angulation difference and defect depth (p < 0.1). Orthoradial projection reduced underestimation of radiographic assessment of bone loss. LMSRT underestimated interproximal bone loss to a lesser extent than conventional evaluation by loupe.

Alveolar Bone Loss↗
PubMed1998

Periodontal surgery of vertical bony defects with or without synthetic bioabsorbable barriers. 12-month results.

The aim of the present study was to clinically and radiographically compare guided tissue regeneration (GTR) therapy with bioabsorbable polyglactin 910 barriers and conventional periodontal surgery in intrabony defects. In 26 patients with advanced periodontitis, 29 teeth exhibiting interproximal intrabony defects were treated; 15 by conventional periodontal surgery (control) and 14 by GTR (test). Before and 12 months after surgery, clinical parameters were assessed and standardized radiographs were taken. On the radiographs the distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC), and the CEJ to the most apical extension of the bony defect (BD) were measured using a computer-assisted analyzing device (LMSRT). Twelve months after surgery, 24 patients with 27 lesions were available for examination. For both methods statistically significant (P < 0.001) probing depth (PD) reduction (mean +/- standard deviation) of -4.49 +/- 1.94 mm (n = 13, test) and -3.22 +/- 1.48 mm (n = 14, control), as well as clinical attachment gain (CAL-V) of 3.41 +/- 1.59 mm (test) and 2.07 +/- 1.10 mm (control), was observed. Radiographic changes of the distance CEJ to AC of -0.95 +/- 1.72 mm (n = 9, test), and -0.98 +/- 1.53 mm (n = 11, control) were not significant. A significant bony fill (distance CEJ-BD) of 1.05 +/- 1.22 mm was observed for the test group (P < 0.01); the 0.68 +/- 2.04 mm bony gain for the control group was not statistically significant. The PD reduction (P < 0.05) and attachment gain (P < 0.01) in the test group was statistically significantly more favorable than in the control group. Twelve months after surgery, statistically more favorable PD reduction and attachment gain was observed using polyglactin 910 barriers than compared to conventional flap surgery. Hence, the use of bioabsorbable barriers for therapy of intrabony defects may be recommended.

Absorbable Implants↗
PubMed1998

Influence of different etching times on hybrid layer formation and tensile bond strength.

PURPOSE: To correlate the thickness of the dentin/resin hybrid layer and the influence of different etching times to the composite resin tensile bond strength. MATERIALS AND METHODS: 775 human molars were prepared by removing the occlusal cusps to expose middle dentin using a microtome saw. Five commercially available dentin bonding agents were applied according to the manufacturers' instructions. Only the etching times were varied. For confocal laser scanning microscopy (CLSM) measurements, 325 teeth were used and the etching times were varied (not etched, 15, 30, 60 or 120 seconds). The primer components or self-priming adhesive, respectively, were fluorescence-labeled by rhodamine B isothiocyanate. In each case, the prepared surfaces were then covered by a layer of composite resin, sectioned and examined using a CLSM in fluorescent mode. The extension of hybrid layers was quantified by measuring the distances between the dentin-composite junction to a visible boundary. For the tensile bond strength measurements (Zwick testing machine), 450 molars were prepared, using different dentin etching times (not etched, 15, 30, 60, 120 and 180 seconds). RESULTS: A hybrid layer was found in all etched teeth. The CLSM data gave evidence for an exponent-function relationship between the periods of etching and the thickness of the hybrid layer. The highest tensile bond strengths were achieved after 15 s of etching, followed by 30 s and 60 s. Under these etching conditions and irrespective of the bonding agent, bond strengths were significantly higher (P < or = 0.05) than without etching or after 120 and 180 s of etching. There was no linear correlation between the thickness of the hybrid layer and the bond strength.

Acid Etching, Dental↗
PubMed1997

Clinical evaluation of Helioseal F fissure sealant.

Unfilled resins are commonly in use as sealant material. In addition, there are filled sealants available. Helioseal F is a newly developed filled material with fluoride release. In this clinical trial, Helioseal F has been evaluated in one lower molar versus Delton opaque as an unfilled control in lower molars. After 12 months there were no significant differences in retention, porosities, and the number of clinically unacceptable margins between the materials. The complete retention was 30 out of 31 examined teeth for Delton and 28 out of 31 for Helioseal F. After 1 year of clinical testing, these results indicate that a sealant containing fluoride-releasing particles did not show a significant difference in retention rate compared to an unfilled conventional sealant. However, long-term results concerning marginal adaptation should be evaluated.

Adolescent↗
PubMed1997

Caries prevalence and treatment needs of 7- to 10-year-old schoolchildren in southwestern Germany.

The caries status of 1784 children aged 7 to 10 years was examined in a cross-sectional, epidemiological study in the Rhine-Neckar-District. Results showed that 30.5% of the children had caries-free primary and 65.2% had caries-free permanent teeth. The d(m)ft index was 2.68, and the D(M)FT averaged 0.76. As in previous studies, a high risk caries group was found, with 10% of all children showing more than 50% of all carious and filled teeth in the permanent dentition. Overall, 45.6% of the children's primary teeth and 16.3% of their permanent teeth needed treatment. As indicated by higher dt:ft (DT:FT) ratios in younger age groups, dentists preferred treating older children. Apart from a higher caries prevalence in primary teeth in males, no significant sex differences were found. Children of rural origin had a higher caries experience. The results confirm previous data showing considerable improvements with a declining caries experience in the young population. But the caries status of German pre-teenage children is still moderately high according to WHO criteria. For further improvements, considerable efforts have to be made with special emphasis on prevention in high risk caries groups.

Age Factors↗
PubMed1997

Comparative in vitro investigation of different methods for temporary root canal filling with aqueous suspensions of calcium hydroxide.

Three methods for temporarily filling root canals with calcium hydroxide pastes were compared. Each of 20 root canals of extracted, human, single-rooted teeth was shaped with hand instruments under standardized conditions up to ISO size 50 and filled using a syringe system, a lentulo spiral or an endodontic reamer. Quality of fillings was assessed radiographically and by inspecting ground preparations. Ridit (relative to an identified distribution) analysis was employed to confirm differences in frequencies of certain quality criteria obtained with various application methods. With regard to degree of obturation and occurrence of porosities, application of temporary fillings with a lentulo spiral or syringe system revealed significantly better results than application with hand instruments (reamer). No differences with regard to degree of obturation were detected when comparing results obtained with syringe or lentulo. Fewer porosities in the apical part of the root canal were seen, both on radiographs and ground sections, with the syringe system compared with the lentulo spiral. In the presence of some contradictory reports found in the literature, the present study suggests that, after straight or slightly curved root canals have been shaped up to at least ISO size 50, high quality temporary root canal fillings may be obtained by application of an aqueous suspension of calcium hydroxide with a syringe system.

Calcium Hydroxide↗
PubMed1997

Applications of confocal laser scanning microscopy to dental bonding.

The introduction of confocal laser scanning microscopy (CLSM) has provided a valuable new technique for the visualization of bonding structures such as a hybrid layer in dentin (Watson, 1989, 1991). In the case of seven commercially-available dentin bonding systems, it could be demonstrated that the CLSM renders considerably more detailed information than the SEM because of its non-destructive nature and because of the possibility of a distinction between components of bonding agents. With most of the bonding systems, measurements of the thickness of the hybrid layer could be carried out when the primer component was labeled with rhodamine B. It was found that this thickness is significantly increased by increases in etching time and only slightly decreased by increases in the drying time of the dentin and of the primer. When rhodamine B was used for dye penetration tests on four different dentin bonding systems, a leakage within the demineralized zone in the dentin was found in each of the specimens. This structure appears similar to that which Sano et al. (1995) called "nanoleakage". The amount of nanoleakage could not be measured by this method. In the case of enamel or ceramic bonding, a penetration zone was found which corresponded to the etching patterns found in enamel and ceramics, respectively. We conclude that CLSM can offer a wealth of new information about bonding morphology and, therefore, should be used in addition to conventional methods so that the maximum information can be obtained.

Acid Etching, Dental↗
PubMed1997

Dentinal adhesion and histomorphology of two dentinal bonding agents under the influence of eugenol.

This study examined the influence of eugenol on the dentinal adhesion of an enamel-dentin bonding agent that removes the smear layer (total-etch technique) and a system that partially dissolves the smear layer (self-conditioning adhesive system). The tensile bond strength was measured on flat, dentinal surfaces after application and removal of pure eugenol for 15 minutes and a eugenol-containing temporary luting agent for 24 hours. In addition, the resin-dentin interface was evaluated with confocal laser scanning microscopy. Dentinal adhesion was found to be significantly reduced after the application of eugenol when a dentin bonding agent that dissolves the smear layer was used. Under confocal laser scanning microscopy, the resin-dentin interdiffusion zone of both adhesive was found to be changed, not only after application of eugenol but also after application of a eugenol-containing temporary luting agent.

Adhesiveness↗
PubMed1996

The reproducibility and validity of furcation measurements using a pressure-calibrated probe.

The furcation involvement of 100 molars in 25 patients suffering from moderate to advanced periodontitis was investigated. The horizontal probing attachment level (PAL-H) within the furcations was assessed 2x within 2 weeks using the pressure-calibrated (0.25 N) flexible plastic universal explorer version of the TPS probe (TPS). To determine the measurement error of PAL-H assessments, the standard deviation of single measurements was calculated. The measurements were repeated using a colour-coded Nabers probe and compared to the TPS assessments. 253 furcations were evaluated (100 buccal, 47 lingual, 53 mesiolingual and 53 distolingual, respectively). For buccal, lingual, mesiolingual and distolingual furcations, the standard deviations were 0.486 mm, 0.598 mm, 0.846 mm, 1.039 mm, respectively. Measurement error was less in buccal and lingual furcations than in mesiolingual and distolingual sites (p < 0.005). The agreement of replicate measurements of furcation degrees was excellent for buccal and lingual furcations (weighted kappa [standard error] 0.824 [0.076] and 0.779 [0.107], respectively), but only moderate for mesiolingual and distolingual furcations (weighted kappa 0.688 [0.096] and 0.544 [0.101], respectively). Only in distolingual sites there was a significant (p < 0.025; paired t-test) underestimation of PAL-H by the TPS as compared to the Nabers probe. At all locations the TPS underestimated furcation degrees significantly (p < 0.1; Stuart-Maxwell's chi 2) as compared to Nabers probe. Measurement error of mesiolingual and distolingual furcations was significantly higher than of buccal or lingual sites. The reproducibility of PAL-H measurements in furcations using TPS is comparable to data published for scorings with colour-coded Nabers probes. Through and through furcations are likely to be underestimated by using the flexible plastic version of the TPS probe. Hence, it seems to be unsuitable for a proper assessment of the degree of furcation involvement.

Adult↗
PubMed1996

Radiographic evaluation of bone regeneration following periodontal surgery with or without expanded polytetrafluoroethylene barriers.

In 16 patients with advanced periodontitis, 23 teeth exhibiting interproximal intrabony defects were treated by conventional periodontal surgery (n = 10, control) or guided tissue regeneration (GTR) technique using expanded polytetrafluoroethylene (ePTFE) barriers (n = 13, test), respectively. Clinical parameters were assessed before and 6 months after surgery. Presurgically and 3 and 6 months postsurgically standardized bite-wing radiographs were taken. Using a loupe and a computer-assisted system, respectively, the distances from the cemento-enamel junction (CEJ) to alveolar crest (AC) and CEJ to the most apical extension of bony defect (BD) were measured. The average gain of attachment was assessed 2.33 mm in the control group and 3.17 mm in the test group. The bony fill was measured 0.97 mm and 0.97 mm in the control group and 0.93 mm and 1.68 mm in the test group after 3 and 6 months, respectively, using a loupe. Using a computer-assisted system 0.83 mm and 1.82 mm of bone fill could be measured (control) and 0.76 mm and 1.79 mm (test) after 3 and 6 months, respectively. Compared to the gold standard of surgical measurements, the computer-assisted analysis of radiographs underestimated bone loss significantly less than evaluation with a loupe (P < 0.002). Compared to conventional periodontal surgery, the GTR technique resulted in higher attachment gain and bony fill. However, the high variation of surgical results in the test group prevented the calculation of a statistically significant difference.

Adult↗
PubMed1996

Experimental investigation of the shear strengths of teeth in the region of the dentinoenamel junction.

The shear strengths of human incisors, canines, premolars, and molars and bovine incisors in the region of the dentinoenamel junction were tested. The median shear strength of all human teeth, 38.99 MPa, was not significantly different from that of bovine teeth, 37.40 MPa. Among the groups of human teeth, the highest median shear strength was obtained from mandibular premolars (46.15 MPa), and the lowest from mandibular canines (32.63 MPa). Physical treatments (cooling or drying) led to a significant reduction in shear strengths. A similar effect was found after exposure to amino butyrate (a caries-removing agent) but not after exposure to sodium hypochlorite (used in endodontic treatment). In all investigated groups of teeth, the fracture areas were mainly in dentin and never exactly at the dentinoenamel junction; indicating that the cohesion of dentin, not the adhesion between dentin and enamel, is the limiting factor in the shear strength.

Aminobutyrates↗
PubMed1995

Effect of root canal filling materials containing calcium hydroxide on the alkalinity of root dentin.

The effect of root canal filling pastes containing calcium oxide resp. calcium hydroxide on the alkalinity of extracted human teeth was investigated using a colour indicator (cresol red). An aqueous suspension of calcium hydroxide (Pulpdent), which is normally used for temporary root canal filling, most consistently produced alkalinity. Removal of the smear layer following instrumentation of the root canal led to increased proportion of alkaline-positive spots in dentinal locations distant from the canal. A clearly smaller effect was found with a calcium salicylate cement (Sealapex) and an oil-paste (Gangraena Merz), both of which are available for definite root canal fillings. Following removal of the smear layer, these hard-setting preparations caused moderate alkalinity in dentin adjacent to the canal but no effect was observed in locations more distant from the canal. Neither at locations adjacent to nor distant from the root canal was alkalinity found when another calcium salicylate cement (Apexit) was used. Apparently the release of hydroxyl ions into root dentin from calcium hydroxide containing root canal filling materials is not solely influenced by the absolute amount of calcium hydroxide, but also depends on other ingredients which variably inhibit the release of these ions.

Binomial Distribution↗
PubMed1994

Localized alveolar ridge augmentation before orthodontic treatment. A case report.

Extraction spaces are usually characterized by narrow, atrophic alveolar ridges, which make it difficult to move teeth orthodontically within these areas. Guided tissue regeneration is often used for alveolar ridge augmentation in implantology. In the case presented, localized alveolar ridge augmentation was performed as a preliminary procedure before orthodontic closure of an edentulous space. Guided tissue regeneration enhances the possibilities of orthodontic treatment in adult patients.

Adult↗
PubMed1994

The reliability of furcation measurements.

The furcation involvement of 100 molars in 25 patients suffering from moderate to advanced periodontitis was investigated. Presurgically, the horizontal probing attachment level (PAL-H) within the furcations was assessed 2 x within 14 days. To determine the measurement error of PAL-H, the standard deviation of single measurements was calculated. The measurements were repeated intrasurgically and compared with presurgical assessments of furcation degrees. The overall standard deviation of single measurements was 0.739 mm. For buccal, lingual, mesiolingual and distolingual furcations, the standard deviations were 0.602 mm, 0.559 mm, 0.759 mm, 1.099 mm, respectively; measurement error was less in buccal and lingual furcations than in distolingual furcations (p < 0.001). The agreement of replicate measurements of furcation degrees was excellent for buccal, lingual and mesiolingual furcations (weighted k - coefficients between 0.776 and 0.944), but only moderate for distolingual furcations (kw = 0.706). Multiple linear regression analysis revealed significant influence of furcation depth, width and furcation location on differences of PAL-H (p < 0.05). There was no significant difference between furcation degree as assessed presurgically and intrasurgically.

Adult↗
PubMed1993

[Microscopic studies of the structures of different dental floss types].

26 different dental flosses, made from silk, polyamide (Nylon) or Teflon, were analyzed with respect to their surface structure and their cross-section. Principally, two different types of manufacturing could be distinguished. The dental flosses either consisted of a large number of individual fibers, or a single, falted membrane. Even flosses that were manufactured in the same manner revealed considerable differences. Apart from the chemical composition, the structure of dental flosses is decisive for their use and this is why an exact classification would be desirable. In this study the requirements for classifying dental flosses are provided.

Dental Devices, Home Care↗
PubMed1993

[The effect of ultrasonic condensation on gold condenser fillings and on the abutting dental hard tissue].

A prototype ultrasonic condensation device was applied to condense two class V mat-gold fillings in each of 10 extracted molars (group A). For 10 other molars a conventional electric device was used (group B). In five molars of each group the nib face of the condenser was not brought into direct contact with the cavity margins (AI/BI); in the other five molars of the sample this was done intentionally (AII/BII). Only one of the two fillings in each tooth was polished. Replicas of the fillings were examined for marginal adaptation by means of scanning electron microscopy (SEM). After dye penetration for 24 h, ground sections of the teeth were examined by light microscopy and SEM. Enamel cracks and cementum injuries were predominantly observed in unpolished fillings of group AII and BII. The marginal adaptation in group AI was significantly better than in group AII, BI, BII, respectively. The polished fillings demonstrated a significantly lower incidence of dye penetration than unpolished restorations. Our results indicate that only direct treatment of the cavity margins with the ultrasonic device causes enamel cracking and cementum injuries. Avoidance of direct treatment of the cavity margins seems to result in better marginal adaptation. In addition to that, polishing seems to lead to lower rates of microleakage.

Dental Abutments↗