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Biomedical subjects

E Hellwig

Publications and source records attributed to E Hellwig.

At least 19 recordsLinked to original sources
PubMed2006

Two-year evaluation of a new nano-ceramic restorative material.

The purpose of this prospective study was to evaluate the clinical performance of a new restorative material (Ceram.X) in combination with a new primer-adhesive (K-0127). One operator placed two Class I or II restorations in molars of 43 patients. One molar was restored with Ceram.X/K-0127, the other one with Tetric Ceram/Syntac Classic. At baseline, after 1 and 2 years, the restorations were evaluated by one evaluator using modified Ryge's criteria. After 2 years, 31 patients were examined. One Ceram.X-restoration had to be removed for root canal treatment due to pulpitis. Thus, failure rate of Ceram.X was 3.2% and of Tetric Ceram, 0%. In both groups, no sensitivity, no recurrent caries, and no changes in surface texture were recorded after 2 years. One restoration in each group showed slight changes in color stability (score B). Marginal discoloration (score B) was found concerning three Ceram.X-restorations (10.0%) and two Tetric Ceram-restoration (6.5%). Marginal integrity was score B for four Ceram.X-restorations (13.3%) and for four Tetric Ceram-restorations (12.9%). No statistically significant differences were found (p>0.05). After 2 years of clinical service, 96.8% of Ceram.X/K-0127 and 100% of Tetric Ceram/Syntac Classic restorations were in place and performed clinically well.

Ceramics↗
PubMed2006

Performance of a new laser fluorescence device for the detection of occlusal caries in vitro.

UNLABELLED: The new device DIAGNOdent pen based on red laser light induced fluorescence was introduced for the detection of approximal and occlusal caries. The aim of this study was to test its performance on occlusal surfaces. The new device comes with two different sapphire fibre tips: a cylindrical tip and a conical tip. The two new sapphire fibre tips were used and compared with the tip currently available with DIAGNOdent (DD). METHODS: The teeth were selected from a pool of extracted permanent human molars, which were stored frozen at -20 degrees C, until use. Prior to being measured the teeth were defrosted and cleaned. One hundred and nineteen teeth were selected and measured with the old tip and with the two new tips of the new device by two independent assessments. The teeth were histologically prepared and assessed for caries extension. RESULTS: Specificity values for D(1), D(2) and D(3) ranged between 0.69 and 0.89, sensitivity between 0.78 and 0.96. There were no statistically significant differences obtained between the two tips of the new and the one tip of the old device (p>0.05). Intra-examiner reliability with kappa values of >0.83 was high. CONCLUSIONS: In this study, the new laser fluorescence device performed on occlusal surfaces as well as the available device.

Adult↗
PubMed2006

Detectability of residual Epiphany and gutta-percha after root canal retreatment using a dental operating microscope and radiographs--an ex vivo study.

AIM: To compare the detectability of residual Epiphany and gutta-percha after root canal retreatment using a dental operating microscope and radiographic examination with the residual area measured after rendering the roots transparent. METHODOLOGY: Sixty extracted single-rooted maxillary central incisor teeth were enlarged to apical size 40. Thirty canals were filled using vertically compacted Epiphany, the remainder were filled with vertically compacted gutta-percha and AH Plus sealer. After re-instrumentation to apical size 50, radiographs of the roots were taken in buccolingual and mesiodistal direction. Residual filling material was categorized by three observers using the radiographs and a dental operating microscope. The area of remaining material that was made visible by radiographs was measured with the aid of a computer image analysis programme. After clearing the roots, areas of residual filling material on the root canal wall were measured using a microscope. RESULTS: Computer image analysis of the radiographs showed significantly smaller areas of remaining gutta-percha and Epiphany compared with the analysis of the transparent teeth that revealed only one absolutely clean root (Epiphany). Especially in the gutta-percha group, the scores determined by the observers using radiographic examination gave an over-optimistic impression of cleanliness compared with the scores determined by the visualization through the microscope. CONCLUSION: Especially for remaining gutta-percha, the operating microscopes provided better detection of residual root filling material in retreated maxillary incisor teeth.

Dental Pulp Cavity↗
PubMed2006

Effects of irradiation on in situ remineralization of human and bovine enamel demineralized in vitro.

The objective of this study was to evaluate the effects of irradiation and surface condition on in situ remineralization of demineralized human and bovine enamel. Specimens (n=96) obtained from 24 human molars and 24 bovine incisors were prepared. The surfaces of half of the specimens were abraded while the others remained natural. Each of the 12 human and bovine abraded and sound specimens was irradiated fractionally up to 46.5 Gy (3.1 Gy/day, 5 days/week), while the remaining samples were not irradiated. Prior to and following the demineralization (pH 5.0; 14 days) all specimens were partly covered with nail varnish (control). After in vitro demineralization 2 irradiated and 2 nonirradiated specimens were inserted into both buccal aspects of 12 intraoral appliances, which were worn by 12 persons for a period of 6 weeks. All samples were brushed twice a day with a fluoride-containing toothpaste. Mineral analyses revealed a significant influence on mineral loss (DeltaZdemin), mineral gain (DeltaDeltaZ), lesion depth (LDdemin), and lesion depth reduction (DeltaLD) of the variables 'material' and 'irradiation' (p<0.05; ANOVA). Reciprocal interactions could be observed between these two variables for DeltaZdemin, DeltaDeltaZ, and LDdemin, due to significantly reduced values found for the irradiated, abraded bovine specimens compared to the nonirradiated ones (p<0.05; Bonferroni post hoc test). It can be concluded that neither irradiation nor abrasion influenced in vitro demineralization or in situ remineralization of the human specimens, whereas abrasion hampered demineralization in irradiated, bovine specimens.

Adult↗
PubMed2006

Oral hygiene products and acidic medicines.

Acidic or EDTA-containing oral hygiene products and acidic medicines have the potential to soften dental hard tissues. The low pH of oral care products increases the chemical stability of some fluoride compounds, favors the incorporation of fluoride ions in the lattice of hydroxyapatite and the precipitation of calcium fluoride on the tooth surface. This layer has some protective effect against an erosive attack. However, when the pH is too low or when no fluoride is present these protecting effects are replaced by direct softening of the tooth surface. Xerostomia or oral dryness can occur as a consequence of medication such as tranquilizers, anti-histamines, anti-emetics and anti-parkinsonian medicaments or of salivary gland dysfunction e.g. due to radiotherapy of the oral cavity and the head and neck region. Above all, these patients should be aware of the potential demineralization effects of oral hygiene products with low pH and high titratable acids. Acetyl salicylic acid taken regularly in the form of multiple chewable tablets or in the form of headache powder as well chewing hydrochloric acids tablets for treatment of stomach disorders can cause erosion. There is most probably no direct association between asthmatic drugs and erosion on the population level. Consumers, patients and health professionals should be aware of the potential of tooth damage not only by oral hygiene products and salivary substitutes but also by chewable and effervescent tablets. Additionally, it can be assumed that patients suffering from xerostomia should be aware of the potential effects of oral hygiene products with low pH and high titratable acids.

Acids↗
PubMed2006

Risk assessment and preventive measures.

A prerequisite for preventive measures is to diagnose erosive tooth wear and to evaluate the different etiological factors in order to identify persons at risk. No diagnostic device is available for the assessment of erosive defects. Thus, they can only be detected clinically. Consequently, erosion not diagnosed in the early stage may render timely preventive measures difficult. In order to assess the risk factors, patient should record their dietary intake for a distinct period of time. Then a dentist can determine the erosive potential of the diet. Particularly, patients with more than four dietary acid intakes have a higher risk for erosion when other risk factors (such as holding the drink in the mouth) are present. Regurgitation of gastric acids (reflux, vomiting, alcohol abuse, etc.) is a further important risk factor for the development of erosion which has to be taken into account. Based on these analyses, an individually tailored preventive program may be suggested to the patients. It may comprise dietary advice, optimization of fluoride regimes, stimulation of salivary flow rate, use of buffering medicaments and particular motivation for nondestructive toothbrushing habits with a low abrasive toothpaste. The frequent use of fluoride gel and fluoride solution in addition to fluoride toothpaste offers the opportunity to reduce somewhat abrasion of tooth substance. It is also advisable to avoid abrasive tooth cleaning and whitening products, since they may remove the pellicle and may render teeth more susceptible to erosion. Since erosion, attrition and abrasion often occur simultaneously all causative components must be taken into consideration when planning preventive strategies.

Acids↗
PubMed2004

Impact of the intraoral location on the rate of biofilm growth.

The aims of the present study were: a) to assess the impact of the intraoral location on the rate of biofilm growth, and b) to establish an in vivo biofilm model to examine intraoral biofilm growth. Eight healthy volunteers wore acrylic splints with 15 glass slabs each in the upper and lower jaws to build up plaque. After 48 h, the specimens were removed and stained using the vital fluorescence technique. Biofilm thickness was evaluated by confocal laser scanning microscopy (CLSM). The mean plaque thickness amounted to 77.6 +/- 29.1 microm on the buccal sites of the upper jaw and 71.9 +/- 26.3 microm on the buccal sites of lower jaw. On the palatal site a biofilm of 52.1 +/- 26.2 microm thickness was grown, which was significantly less compared with the other locations evaluated (p < 0.001). The results demonstrate that the in situ biofilm thickness on the buccal sites was similar irrespective of the location in the oral cavity. The new splint system described may be a useful tool for further standardised experimental studies regarding influences on growth and structure of intraoral biofilms.

Adult↗
PubMed2004

Influence of buffering effects of dentifrices and fluoride gels on abrasion on eroded dentine.

OBJECTIVE: Evaluation of abrasion resistance of eroded and non-eroded dentine brushed with experimental dentifrices and gels of varying buffering capacities. DESIGN: One hundred and twenty human dentine specimens were distributed among six groups (A-F) according to the different buffering capacities of experimental toothpastes and gels. The dentifrices (pH: 4.5) and gels (pH: 4.5) differed in fluoride content, RDA-value and buffer capacity (given as mg KOH needed for neutralisation): (A) 0.125%F, RDA: 77, 6mg KOH; (B) 0.125%F, RDA: 125, 24mg KOH; (C) 0.125%F, RDA: 129, 12mg KOH; (D) 0%F, RDA: 81, 1.55mg KOH; (E) 1.25%F, RDA: 21, 8.5mg KOH; (F) 0.125%F, RDA: 7, 3.11mg KOH. Ten specimens were cycled through three alternating demineralisations (1% citric acid, 5min) and remineralisations (artificial saliva, 1min) including brushing abrasion in an automatic brushing machine (2 x 2000 strokes). Ten samples of each group were not eroded, but only brushed. RESULTS: After three cycles, loss of dentine was determined by profilometry (mean +/- S.D. [microm]). Eroded samples: (A) 37.12+/-4.95; (B) 48.67+/-4.77; (C) 39.88+/-3.76; (D) 32.92+/-2.67; (E) 3.65+/-1.35; (F) 6.47+/-1.31. Uneroded samples: (A) 30.78+/-6.47; (B) 37.84+/-7.75; (C) 30.07+/-3.05; (D) 26.93+/-2.30; (E) 1.76+/-0.94; (F) 0.51+/-0.18. Analysis of variance revealed significantly higher abrasion values for the eroded compared to the non-eroded samples (P<or=0.05). Dentifrices with same pH-value, fluoride content and similar RDA-values but a higher buffering capacity exhibited significantly more abrasion than toothpastes with lower buffering capacity. Highly-concentrated fluoride gel with higher buffering capacity lead to less abrasion values compared to the gel with low fluoride concentration and low buffering capacity. CONCLUSION: Toothbrushing abrasion behaviour of eroded dentine may be influenced by the fluoride content, RDA-value and buffering capacity of the applied dentifrice or gel.

Buffers↗
PubMed2004

An in vitro investigation of penetration depth of dentine bonding agents into carious dentine.

The aim of the present in vitro study was to determine the penetration depth of dentine bonding agents into carious dentine as a possible strategy in caries treatment of deep lesions. Forty-eight extracted carious teeth were used for the experiments and divided in four groups. In a split-tooth design, one half of each tooth was treated without caries excavation, and the second half after caries excavation. In group 1 the teeth were treated with Prime & Bond 2.0 without phosphoric acid etching, and in group 2 with phosphoric acid etching. In group 3, the teeth were treated with All-Bond 2 without phosphoric acid etching, and in group 4 with phosphoric acid etching. Bonding agents were marked with an orange dye prior to application. The composition of the bonding agents had no significant influence on penetration depths. The mean thickness of the outer, necrotic caries zone in unexcavated specimens was 117 microm (+/-126). Bonding agents penetrated significantly deeper into unexcavated carious dentine (mean 124 +/- 76 microm) compared with excavated dentine (11 +/- 14 microm) and sound dentine (3 +/- 4 microm). Acid etching significantly reduced the thickness of the outer caries zone, and the penetration depth of the bonding agents into unexcavated carious specimens by approximately 50%, and increased it into sound dentine. The results indicate that dentine bonding agents could completely penetrate the unexcavated outer carious dentine in 90% of specimens. Further studies are required to determine whether further caries activity is arrested after treatment with dentine bonding procedures.

Dental Caries↗
PubMed2003

Effect of mineral supplements to citric acid on enamel erosion.

The aim of this study was to evaluate the effect of mineral supplements to citric acid (1%; pH 2.21) on enamel erosion under controlled conditions in an artificial mouth. From each of 156 bovine incisors one polished enamel sample was prepared. The samples were divided among 13 experimental groups (n=12). In group 1 citric acid only was used (control). In groups 2-10 either calcium, phosphate or fluoride in various low concentrations was admixed to the citric acid. In groups 11-13 the citric acid was supplemented with a mixture of calcium, phosphate and fluoride. For demineralisation the specimens were rinsed with the respective solution for 1 min, immediately followed by a remineralisation period with artificial saliva (1 min). The specimens were cycled through this alternating procedure five times followed by rinsing for 8 h with artificial saliva. The de- and remineralisation cycle was repeated three times for each specimen interrupted by the 8 h-remineralisation periods. Before and after the experiments, the specimens were examined using microhardness testing (Knoop hardness) and laser profilometry. Hardness loss and enamel dissolution was significantly higher for the controls as compared to the remaining groups. Significantly lowest hardness loss for all groups was recorded for group 12 with admixture of calcium, phosphate and fluoride to citric acid. The significantly highest enamel loss was recorded for the controls compared to all other samples. Groups 3 and 4 revealed significantly lower and higher tissue loss compared to the remaining groups (2-13), respectively. The other groups did not differ significantly from each other. Modification of citric acid with calcium, phosphate and fluoride exerts a significant protective potential with respect to dental erosion. However, with the low concentrations applied enamel dissolution could not be completely prevented.

Animals↗
PubMed2002

Fluoride uptake, retention, and remineralization efficacy of a highly concentrated fluoride solution on enamel lesions in situ.

Repeated topical application of concentrated fluorides is known to reduce caries. Little is known about fluoride retention and remineralization in incipient caries lesions following a single application. We investigated fluoride and the remineralization kinetics of a single application of elmex fluid (GABA International AG, Münchenstein, Switzerland; 10,000 ppm F) in initial enamel lesions. In this double-blind, placebo-controlled, randomized, crossover in situ study that conformed to good clinical practice, volunteers received intra-oral removable appliances carrying demineralized enamel samples after application of elmex fluid or placebo. After 5 min, 1, 2, 3, and 4 weeks in situ, KOH-soluble fluoride (KOHF), structurally bound fluoride (SBF), mineral gain, and lesion depth reduction were measured. Elmex fluid promoted higher KOHF and SBF at all times, decreased KOHF with time, increased SBF up to 3 weeks, and registered a higher mineral gain than placebo. Volunteers with higher stimulated salivary flow rates had lower fluoride uptake, but higher mineral gain. In conclusion, a single application of highly concentrated fluoride solution increases remineralization.

Adolescent↗
PubMed2001

Chemomechanical caries removal: a comprehensive review of the literature.

Compared to the past, caries removal has become more efficient, however inherent fundamental drawbacks of the drilling approach have remained: unpleasantness to patients, need for local anesthesia, and potential adverse effects to the pulp due to heat and pressure. Chemomechanical caries removal, introduced almost three decades ago, was claimed to be a non-invasive alternative for the removal of carious dentine. In essence, the technique involved applying a solution onto the decayed dentinal tissue, allowing it to soften it, and, finally, scraping it off with blunt hand instruments. The partially degraded collagen in carious dentine was chlorinated by chemomechanical caries removal solutions. This chlorination affected the secondary and/or quaternary structure of collagen, by disrupting hydrogen bonding. Carious material removal was thus facilitated. The purpose of this paper is to perform a comprehensive review of the literature regarding chemomechanical caries removal, including the most recently available product, the initial reports on which warrant renewed interest in the approach.

Aminobutyrates↗
PubMed2001

Influence of resin cement viscosity on microleakage of ceramic inlays.

OBJECTIVES: The aim of the present investigation was to evaluate the effect of the different viscosities of two resin luting cements on microleakage of ceramic inlays at dentinal margins. The effect of the width of the space between inlay and tooth, on the quality of the marginal seal was also investigated. METHODS: Mesial and distal class V cavities were prepared in 48 extracted third molars. The incisal margins of the cavities were in enamel and the cervical margins in dentin. Subsequently, Empress inlays with different cervical margin gap dimensions were fabricated. The mean cervical gap dimensions in the respective groups were as follows: group 1 (27 microm); group 2 (232 microm); group 3 (406 microm). Half the inlays in each group (16) were cemented with a low viscous resin luting cement, and half (16) with a highly viscous resin luting cement. The teeth were subjected to occlusal loading with synchronized thermal cycling in a masticatory simulator. Then, the specimens were immersed in basic fuchsin solution, and dye penetration along the cavity walls was measured. In addition, marginal adaptation was analyzed in the SEM at baseline and after loading, using a replica technique. RESULTS: With regard to dye penetration at dentinal margins, the highly viscous cement performed statistically significantly better at dentin/composite margins than the low viscous cement (p=0.0158). These findings are supported by SEM analysis. SIGNIFICANCE: It is assumed that polymerization stress within the luting cement could not be completely compensated for by larger luting spaces. Highly viscous luting cements are recommended for cementing class V inlays in larger luting spaces.

Aluminum Silicates↗
PubMed2001

Erosive potential of oral care products.

Seven oral care products and orange juice as a positive control were tested for the erosive potential by immersing each enamel specimen (10 per group) into solutions of the various products for 10 and 20 min. Before and after the experiment Knoop surface hardness (SMH) was measured. The enamel microstructure before and after immersion was assessed by scanning electron microscopy and confocal laser scanning microscopy. Orange juice produced the most marked losses of hardness after 10 and 20 min. Among the dental hygiene products only the fluoride-free toothpaste produced a significant reduction of hardness after 10 as well as after 20 min. With the exception of Elmex gel, all tested oral care products led to a significant (p < 0.05) increase of enamel hardness. The results of the hardness measurements corresponded with the microstructure findings. It may, therefore, be concluded that the tested fluoride-containing oral care products do not exhibit any erosive potential, which could be picked up with the methodologies under study.

Amines↗
PubMed2001

What is the optimum fluoride concentration needed for the remineralization process?

In vitro experiments could demonstrate that only negligible amounts of fluoride are necessary to promote remineralization of incipient caries lesions. From the clinical point of view, there is evidence that only under certain circumstances is a stabilization of the surface zone of an incipient caries lesion the true mechanism of action of topically applied fluorides. However, an optimum universally valid fluoride concentration needed for this process cannot be defined.

Cariostatic Agents↗
PubMed2000

Effects of additional teaching of final-year dental students on their radiographic diagnosis of caries.

The aim of this study was to evaluate whether the skills of final-year dental students in the diagnostic interpretation of bitewing radiographs could be improved by additional didactic instruction. 6 consecutive classes of students in the same stage of education (last semester in the Department of Operative Dentistry) took part in the investigation from 1995 to 1998. At the beginning of each semester, the same in vivo made bitewing radiograph was demonstrated in a separate radiology revision lecture and interpreted with the students. The intensification of the training in the diagnosis of bitewing radiographs was made when the 4th class of students started. At the end of each semester, each student of the 6 consecutive classes was asked to evaluate the same bitewing radiograph, which had been demonstrated at the start of the semester. The students were not told that they had already diagnosed from this radiograph before. The results of the radiographic diagnosis were then analyzed using an evaluation system paying special attention to the treatment decision. True positive and true negative diagnoses were scored as correct and false positives and false negatives as incorrect. There was no significant difference (ANOVA) in the ability to diagnose from bitewing radiographs between the groups of students who received, and those who did not receive, additional training. The benefits of this type of additional instruction in the last semester in the Department of Operative Dentistry seem only to be important in some individual cases.

Analysis of Variance↗
PubMed2000

Effect of different luting procedures on the seating of ceramic inlays.

This in vitro study evaluated the effect of different luting procedures on the proper seating of ceramic inlays and on the marginal seal through microleakage testing. Sixty mesial-, occlusal-, distal- (MOD) cavities were prepared in third molars, and distributed among four groups. In the control group 1, the cavity surface was treated with dentin and enamel bonding agents; ceramic inlays were placed into the cavity and light cured. In group 2, the dentin and enamel bonding agents were cured prior to the placing of the inlays, and following the insertion. In group 3, the inlays were luted without enamel bonding. In group 4, the inlays were cemented using a one-bottle bonding and two times light curing. The groups with only one time light curing at the end of the luting process exhibited the smallest luting space following cementation. The smallest dye penetration values were obtained for the two groups with separate light curing of the dentin bonding agent. Reducing the film thickness of polymerized dentin bonding agents, i.e. by changing the composition of the bonding agents, could facilitate proper seating of ceramic inlays together with a better marginal seal.

Acid Etching, Dental↗