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Biomedical subjects

Reinhard Hickel

Publications and source records attributed to Reinhard Hickel.

At least 37 records · Page 2Linked to original sources
PubMed2004

The effectiveness of InGaAsP diode laser radiation to detect subgingival calculus as compared to an explorer.

BACKGROUND: The aim of the present study was to compare the ability of the diode laser to detect residual calculus with that of an explorer. METHODS: The root surface of 40 extracted human teeth, each partially covered with subgingival calculus, was instrumented with curets under simulated clinical conditions in a manikin. The samples were randomly assigned to two study groups. In group A, the root surface was treated with an explorer until it appeared free of mineralized deposits upon examination. The samples in group B were instrumented until the relative intensity of fluorescence as induced with diode laser radiation was below a threshold value of 5. The root surface of each sample was then examined for residual calculus using standardized digital images. The statistical analysis was performed with a non-paired t test at a level of significance of 5% (P < 0.05). RESULTS: The root surface of single-rooted teeth showed residual calculus on 0.19 +/- 0.37 x 10(7) microm2 in the laser group and on 0.11 +/- 0.26 x 10(7) microm2 in the explorer group (P = 0.19). For multirooted teeth, the mean calculus-covered area was 0.50 +/- 0.48 x 10(7) microm2 for the teeth evaluated with an explorer and 0.27 +/- 0.43 x 10(7) microm2 for the diode laser group (P = 0.02). CONCLUSION: The present findings indicate that the detection of subgingival calculus is significantly improved using 655 nm diode laser radiation compared to an explorer for molars but not for single-rooted teeth.

Arsenic↗
PubMed2004

Influence of parameters on root surface roughness following treatment with a magnetostrictive ultrasonic scaler: an in vitro study.

BACKGROUND: This in vitro study aimed to evaluate the influence of different parameters, i.e., lateral force, instrument power setting, and the shape of the working tip, on the roughness of root surfaces following treatment with a magnetostrictive ultrasonic scaling device. METHODS: The study sample comprised a total of 102 extracted human molars, premolars, canines, and incisors. The samples were randomly divided into 10 equal units of 10 each for treatment with the ultrasonic device at a lateral force of 0.5 N and 2.0 N, a low and high instrument power setting, and with a straight and angulated shaped working tip. Twenty samples were treated manually using curets at a lateral force of 0.5 N and 2.0 N. Two samples were left untreated as controls. The mean (Ra) and maximum (Rmax) surface roughness of each sample was recorded. The statistical analysis was performed using analysis of variance (three-way ANOVA) at a level of significance of 5% (P < 0.05). RESULTS: The mean surface roughness (+/-SD) using different parameters ranged from 0.6 +/- 0.1 microm to 1.8 +/- 0.3 microm. The maximum surface roughness (+/-SD) was between 4.8 +/- 1.3 microm and 17.2 +/- 4.3 microm. The mean surface roughness (+/-SD) for samples treated with curets at a lateral force of 0.5 N was 0.5 +/- 0.0 microm and 0.4 +/- 0.1 microm at 2.0 N. The maximum surface roughness (+/-SD) was 3.7 +/- 0.8 microm at 0.5 N and 3.9 +/- 1.4 microm at 2.0 N. CONCLUSIONS: The findings of the present study indicate that the shape of the working tip and the lateral force significantly influence the mean and maximum surface roughness of root surfaces treated with a magnetostrictive ultrasonic scaling device. At any specific parameter, the surface roughness was significantly higher for the ultrasonic scaling device as compared to the hand curet.

Analysis of Variance↗
PubMed2004

Influence of the pretreatment of occlusal pits and fissures on the retention of a fissure sealant.

PURPOSE: To evaluate different regimens of enamel conditioning on the retention of a pit and fissure sealant. METHODS: 100 extracted human molars were randomized into 10 experimental groups (n = 10). Conditioning of occlusal pits and fissures was performed with either 37% H3PO4, diamond bur and 37% H3PO4, Er:YAG laser, Er:YAG laser and 37% H3PO4, air abrasion (3 different settings), air abrasion (3 different settings) and subsequent acid etching with 37% H3PO4. 24 hours after placing a compomer-based sealant, the specimens were artificially aged by thermocycling (5/55 degrees C; x1000) and immersed in basic fuchsin dye for another 24 hours. After sectioning, dye penetration along the enamel-resin-interface was determined (% of the fissure depth). Data were statistically analyzed with Kruskal-Wallis H test and Mann-Whitney U test. For qualitative investigations, two further specimens of each group were analyzed in the SEM. RESULTS: Conventional acid etching resulted in significantly superior sealant retention than conditioning with either the Er:YAG laser or air abrasion (irrespective of particle size or air pressure). If mechanical conditioning of the laser or air abrasion was followed by acid-etching, results were statistically equal to the acid-etch only group.

Air Abrasion, Dental↗
PubMed2004

4-year clinical performance and survival analysis of Class I and II compomer restorations in permanent teeth.

PURPOSE: To evaluate the 4-year clinical performance of the compomer Hytac in Class I and II cavities of permanent posterior teeth. METHODS: 53 compomer restorations were placed using the self-conditioning adhesive Hytac OSB (total bonding) without additional phosphoric acid-etching according to manufacturer's instructions. Restorations were rated (modified USPHS criteria) at baseline, after 6, 12, 18, 36 and 48 months in relation to tooth type (molar, premolar), size and class of cavities, isolation type (rubber dam, cotton rolls) and use of a calcium hydroxide liner. After 4 years, 39 restorations (73.6%) were available for examination. Statistical analysis was performed using Kaplan-Meier survival analysis with the logrank test and Fisher's exact test for the failure analysis. RESULTS: After 4 years, the success rate was 84.6%, six restorations failed (15.4%). The average annual failure rate was therefore 3.85%. Loss of marginal integrity was the main cause of restoration failure. The probability that a restoration would remain clinically acceptable after 4 years was calculated to be 89% (Kaplan-Meier). No significant performance differences could be found between any of the restoration groups.

Adhesives↗
PubMed2004

Stabilization effects of CAD/CAM ceramic restorations in extended MOD cavities.

PURPOSE: Using extended, standardized MOD preparations, it was the aim of this in vitro study to examine the performance of CAD/CAM ceramic inlays in comparison to composite inlays after mechanical and thermal fatigue loading in terms of marginal quality and stabilization of the remaining tooth structure. MATERIALS AND METHODS: Standardized cavities with different wall thicknesses were prepared in 90 extracted premolars; 10 additional premolars remained untreated. Composite inlays (Tetric) and CAD/CAM restorations (Cerec II; Vita Mark II) were adhesively placed in the cavities. After loading in a chewing simulator, quantitative and qualitative marginal gap examinations were conducted and fracture resistance determined. RESULTS: The results show that ceramic inlays provide significantly greater stabilization and better marginal quality than do composite inlays. CONCLUSION: Chairside-fabricated ceramic inlays inserted using adhesive technology are able to stabilize weakened cusps. In the case of very thin remaining walls (about 1.3 mm), however, the marginal quality and the cusp-stabilizing effect are also reduced.

Bicuspid↗
PubMed2003

Safety and efficiency of novel sonic scaler tips in vitro.

BACKGROUND: The aim of the study was to evaluate a novel sonic scaler tip for subgingival root surface instrumentation combining high efficiency in calculus removal with minimized risk of root damage through subgingival debridement. METHODS: A metal sonic scaler tip with a paddle-like working end covered with spheroid convexities of 0.8 mm diameter and 0.3 mm height was designed from the aspect of optimized adaptation to the root anatomy (tip-end dimension: 3.0 x 1.5 x 0.6 mm). Using a customary sonic scaler tip as control, instrument efficiency was quantified by measuring the time needed to completely remove calculus on extracted teeth (n=52) under standardized conditions. To quantify the amount of calculus removed, the mean calculus area per tooth was measured on photographs taken before instrumentation. The tips safety was evaluated instrumenting calculus-free root surfaces in vitro (n=18, lateral forces 0.5, 1, 2 N, 20 s instrumentation time, tip angulation 0 degrees ) with subsequent laser-optical determination of resulting root substance loss. RESULTS: Debridement efficiency was significantly higher for the novel tip (0.78+/-0.81 mm2/s completely debrided) than for the conventional tip (0.42+/-0.33 mm2) (Mann-Whitney test, p<0.05). Concerning instrument safety, the novel tip caused significantly less root substance loss than the conventional tip. CONCLUSION: The novel scaler tip appears to be significantly more efficient in calculus removal and less damaging to the root surface than the assessed conventional tip.

Dental Calculus↗
PubMed2003

Effects of 2.94 microm Er:YAG laser radiation on root surfaces treated in situ: a histological study.

BACKGROUND: Previous scanning electron microscopy (SEM) studies using extracted teeth have shown the potential of infrared Er:YAG laser radiation to remove subgingival calculus without causing severe thermal changes, e.g., charring or fusion, to the irradiated root surface. The purpose of the present study was to examine the morphologic changes on root surfaces following Er:YAG laser irradiation in situ using histological observation. METHODS: The periodontal pockets of 6 premolars, canines, and incisors that remained in situ in the jaws of human corpses were irradiated with Er:YAG laser radiation at 60 mJ, 100 mJ, or 180 mJ. The pockets were treated in a similar manner to normal clinical circumstances with a total amount of either 50 or 100 laser pulses. Following laser treatment, the entire tooth, marginal gingiva, and underlying alveolar bone were removed from the jaw. The sections were embedded in methyl-methacrylate, serially cross-sectioned, stained with hematoxylin and eosin or gallamine blue, and examined under a light microscope. Additionally, the extension of the thermally changed tissue areas was determined using digital images and histometry. RESULTS: The histological examination revealed two kinds of thermal changes within the laser-treated root surface. Firstly, a thin superficial layer 5 to 10 microm in width was observed. The surface of this layer showed ultrastructural irregularities. Secondly, a semicircular more deeply stained area close to the apical end of the scaling track beneath the irradiated cementum was observed. The depth of this area ranged from 255 microm to 611 microm and appeared to be independent of the radiation energy. CONCLUSION: In contrast to previous SEM studies, the histological examination indicated thermal changes within the hard tissue bordering the periodontal pocket following Er:YAG laser irradiation.

Aluminum Silicates↗
PubMed2003

Removal of bacterial endotoxin from root surface with Er:YAG laser.

PURPOSE: To determine the potential of 2.94 microm Er:YAG laser radiation to remove bacterial endotoxin from root surfaces. MATERIALS AND METHODS: 40 extracted teeth were divided into four groups of 10 samples each. A 16 mm2 area of the root surface on each sample was inoculated with an aliquot of 7 microl of a lipopolysaccharide suspension at a concentration of 50 IU/ml. LPS was derived from a non-oral Escherichia coli strain (E. coli 055:B5). Source of laser radiation was an Er:YAG laser emitting pulsed infrared radiation at a wavelength of 2.94 microm, with a pulse duration of 250 micros, and a pulse repetition rate of 15 pps. Three specimen groups were irradiated with 105 laser pulses at a radiation energy of 60 mJ, 100 mJ and 140 mJ. One specimen group was untreated (control). The LPS concentration with each sample was determined using a chromogenic, quantitative Limulus-amoebocyte-lysate assay. Statistical analysis was ANOVA and Scheffé-test. RESULTS: Mean LPS yield from the untreated control samples was 50.1 (+/- 35.9) IU/ml. Following laser irradiation the average LPS on the root surfaces was 19.86 (+/- 14.4) IU/ml at 60 mJ, 12.86 (+/- 8.1) IU/ml at 100 mJ and 8.58 (+/- 4.9) IU/ml at 140 mJ.

Decontamination↗
PubMed2003

Three-year clinical performance of a compomer in stress-bearing restorations in permanent posterior teeth.

PURPOSE: To evaluate the 3-year clinical performance of the compomer Hytac in Class I and II cavities of permanent posterior teeth. METHODS: 53 restorations were placed in 14 patients. The compomer Hytac was used with the self-etching adhesive Hytac OSB (total bonding) without additional enamel-etching with phosphoric acid according to manufacturer's instructions. Restorations were rated at baseline and 3 years according to modified USPHS criteria in relation to tooth type (molar, premolar), size and class of cavities, isolation type (rubber dam, cotton rolls) and use of a calcium hydroxide liner. After 3 years, 39 restorations (73.6%) were available for examination. Statistical analysis was performed using Mann-Whitney U test and Fisher's exact test. RESULTS: After 3 years, three restorations failed (7.7%). The success rate was therefore 92.3% with an average annual failure rate of 2.6%. There was no statistically significant difference (P < 0.05) found concerning neither of the USPHS criteria nor the failures between any of the restoration groups.

Bicuspid↗
PubMed2002

Direct posterior restorations: clinical results and new developments.

The longevity of dental restorations is dependent on many different factors, including those related to materials, the dentist, and the patient. The main reasons for restoration failure are secondary caries, fracture of the bulk of the restoration or of the tooth, and marginal deficiencies and wear. The importance of direct-placement, aesthetic, tooth-colored restorative materials is still increasing. Amalgam restorations are being replaced because of alleged adverse health effects and inferior aesthetic appearance. All alternative restorative materials and procedures, however, have certain limitations. Direct composite restorations require a time-consuming and more costly treatment procedure and are actually only indicated for patients with excellent oral hygiene. Glass ionomers can be considered only as long-term provisional restorations in stress-bearing posterior cavities. Future treatment regimens that are made possible by the development of sophisticated preparation techniques, improved dentin bonding agents, and resin-based restorative materials will result in the therapy of more small-sized lesions rather than large restorations. The importance of indirect inlay techniques will shift more and more toward the direct restoratives. As the cavities become smaller, it is to be expected that the use of improved direct restorative materials will provide excellent longevity even in stress-bearing situations.

Bicuspid↗
PubMed2002

Uptake, clearance and metabolism of TEGDMA in guinea pigs.

OBJECTIVE: The resin monomer triethyleneglycoldimethacrylate (TEGDMA) is used as a diluent in many resin-based bonding, cementing and direct tooth filling materials. METHODS: In the present study the uptake and the clearance of 14C-TEGDMA applied via different routes were examined in vivo in guinea pigs. TEGDMA (0.02 mmol/kg by weight labeled with a tracer dose 14C-TEGDMA 0.7Bq/g by weight) was administered by gastric tube or by subcutaneous injection. Urine, feces, and exhaled carbon dioxide were collected for 24h after administration. The animals were killed 24h after the beginning of the experiment and various organs removed and 14C-radioactivity measured. RESULTS: It was apparent that 14C-TEGDMA was taken up rapidly from the stomach and small intestine after gastric administration and was widely distributed in the body following administration by each of the routes. Clearance from most tissues following gastric and intradermal administration was essentially complete within one day. Low fecal 14C-levels (<1% of the administered dose) and urinary levels of about 15% after 24h were noted with each route of administration. Direct measurement of exhaled carbon dioxide showed that 60-65% of the administered dose of 14C left the body via the lungs during 24h. It is likely that 14C-pyruvate is formed in vivo resulting possibly in the formation of toxic 14C-TEGDMA-intermediates. SIGNIFICANCE: Despite using a high administered dose, the peak TEGDMA levels in all tissues examined after 24h were at least 100,000-fold less than known toxic levels.

Analysis of Variance↗
PubMed2002

Antimicrobial effects of 2.94 microm Er:YAG laser radiation on root surfaces: an in vitro study.

OBJECTIVES: This in vitro study investigated the antimicrobial effects of 2.94 microm Er:YAG laser radiation on root surfaces. MATERIALS AND METHODS: The study used 125 extracted teeth which were divided into 2 groups (A, B) of 40 teeth and 3 groups of 15 teeth (C, D, E). A defined and similarly-sized area of the root surface was inoculated with an aliquot of 7 microl of a bacterial suspension of Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Actinobacillus actinomycetemcomitans (ATCC 43719), Eikenella corrodens (ATCC 51724), or Peptostreptococcus micros (ATCC 33270). Subsequently, the samples from each group were further divided into subgroups which have been irradiated either with 55, 75, and 105 (group A, B) or 55 and 75 (group C, D, E) laser pulses. 1 subgroup of each group was left untreated as control. The source of laser radiation was an Er:YAG laser emitting pulsed infrared radiation at a wavelength of 2.94 microm. The number of bacteria was determined using the surface spread plate technique. The statistical analysis was performed using ANOVA followed by the Scheffé-test. RESULTS: Depending on the number of laser pulses the bacterial load in the E. coli group was reduced by the Er:YAG laser radiation after exposure to 105 laser pulses to 5.5% of the initial count and that in the Staph. aureus group to 15.1%. The number of bacteria in case of A. actinomytemcomitans was reduced to 8.3%, in case of E. corrodens to 3.0% and in case of P. micros to 22.0% after application of 75 laser pulses. CONCLUSION: Besides the selective removal of plaque and calculus, the 2.94 microm Er:YAG laser radiation causes reduction in bacteria on root surfaces.

Aggregatibacter actinomycetemcomitans↗
PubMed2002

Root surface roughness following Er:YAG laser irradiation at different radiation energies and working tip angulations.

OBJECTIVES: The determination of roughness of root surfaces following treatment with 2.94 micro m Er:YAG laser radiation at different radiation energies and working tip angulations. MATERIALS AND METHODS: The study sample comprised 85 extracted human molars, premolars, canines and incisors (n = 85). The source of laser radiation was an Er:YAG laser device (KAVO-Key II, System Aesculap Meditec) emitting pulsed infrared radiation at a wavelength of 2.94 micro m, with a pulse duration of 250 micro s, and a pulse repetition rate of 10 pps. The samples were randomly divided into three experimental units, for treatment with a constant amount of 380 laser pulses at a radiation energy of 60 mJ, 100 mJ, and 180 mJ. Each experimental unit was divided into five subgroups of five samples, which were irradiated at a working tip angulations of 15 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees. Five samples were treated mechanically using curettes. Five samples were left untreated as control. The mean (Ra) and maximum (Rmax) surface roughness of each sample was measured using a profilometer. The statistical analysis was undertaken using anova and Scheffé-test at a level of significance of 5% (p < 0.05). RESULTS: Er:YAG laser radiation led to an Ra which ranged from 0.52 micro m (+/- 0.10) to 0.81 micro m (+/- 0.26) and to an Rmax between 3.4 micro m (+/- 0.48) and 9.26 micro m (+/- 3.08). The Ra and Rmax for samples treated with curettes was 0.51 micro m (+/- 0.11) and 5.08 micro m (+/- 4.98), respectively. That for the untreated control samples were 0.53 micro m (+/- 0.15) and 7.07 micro m (+/- 5.48), respectively. CONCLUSIONS: The mean and maximum surface roughness of root surfaces following irradiation with Er:YAG laser was not significantly different to that obtained on samples treated with conventional hand instruments or left untreated. Furthermore, the surface roughness does not depend on the radiation energy and the angulation of the working tip.

Aluminum Silicates↗
PubMed2002

Antibacterial effects of pulsed Nd:YAG laser radiation at different energy settings in root canals.

The in vitro study aimed at the determination of the bacterial reduction in root canals used pulsed Nd:YAG laser radiation without a photosensitizing dye. In addition the temperature change in the root canals was determined during laser irradiation. The study sample was 114 root canals of extracted single-rooted human teeth that have been enlarged mechanically, sterilized, and randomly assigned to two experimental units. The source of radiation was a Nd:YAG laser device emitting pulsed infrared radiation at a wavelength of 1.064 microm, a pulse duration of 100 micros, and a pulse repetition rate of 20 pps. Samples of each experimental unit were inoculated with Escherichia coli (ATCC 25922) or Staphylococcus aureus (ATCC 25923), respectively, and divided into subgroups of 13 teeth each for irradiation for 20 s at 100 mJ or 200 mJ. One subgroup was left untreated as positive control and one subgroup was rinsed with 0.5 ml of sodium hypochloride. After laser treatment or rinsing with sodium hypochloride the number of bacteria in each root canal was determined using the surface spread plate technique. Statistical analysis of the results was performed with ANOVA and Scheffé test at a level of significance of 5% (p < 0.05). In case of E. coli the number of bacteria was reduced from 8.67 x 10(6) (+/-4.11 x 10(5)) colony-forming units (CFU)/ml to 4.39 x 10(4) (+/-1.72 x 10(4)) CFU/ml after laser radiation at 200 mJ. Regarding S. aureus the number of bacteria decreased from 1.44 x 10(6) (+/-1.59 x 10(5)) CFU/ml to 3.8 x 10(4) (+/-1.06 x 10(4)) CFU/ml at a radiation energy of 200 mJ. Rinsing with sodium hypochloride reduced the number of bacteria to 1.03 x 10(3) (+/-4.02 x 10(2)) CFU/ml regarding E. coli and to 1.84 x 10(3) (+/-7.4 x 10(2)) CFU/ml in case of S. aureus. The temperature increase at 100 mJ was 24.3 degrees C (+/-3.9) and that at 200 mJ was 61.8 degrees C (+/-4.2). The Nd:YAG laser radiation has antimicrobial effects in root canals even in the absence of photosensitizing dyes but also causes considerable temperature increase.

Aluminum Silicates↗
PubMed2002

Direct restorative material use of selected practitioners in the United Kingdom.

PURPOSE OF THE INVESTIGATION: To investigate, by questionnaire, the direct restorative materials used by a sample of practitioners from the United Kingdom. BASIC PROCEDURES: A postal questionnaire was distributed to a group of self-selected practitioners, who volunteered to participate in the study. In all 110 practitioners participated in the study. MAIN FINDINGS: The most used material for the restoration of occlusal (Class I) and approximal (Class II) lesions was amalgam with 61% and 73% of practitioners indicating that they used amalgam in this situation. Adhesive tooth-coloured materials, specifically composites and compomers, were preferred by the majority of practitioners for anterior approximal (Class III) and incisal (Class IV) restorations with compomer preferred for Class V restorations including non-carious cervical lesions and for the restoration of primary teeth. PRINCIPAL CONCLUSIONS: It is concluded that the general practitioners surveyed in this study tend to use amalgam for the restoration of Class I and II lesions as opposed to resin composite. The majority of practitioners in this study used compomers, a relatively new group of restorative materials, with little evidence of traditional glass-ionomer cements being used routinely.

Adult↗
PubMed2002

Clinical management of hypohidrotic ectodermal dysplasia with anodontia: case report.

Ectodermal dysplasia is a rare hereditary disorder with a characteristic physiognomy. The case of a 5-year-old child with hypohidrotic ectodermal dysplasia and complete anodontia is presented. Because of the anodontia and the need for treatment at an early age, the prosthetic management of such a young child can be difficult. Complete dentures were provided to encourage a normal psychological development and to improve the function of the stomatognathic system.

Anodontia↗
PubMed2002

Subgingival calculus detection with fluorescence induced by 655 nm InGaAsP diode laser radiation.

BACKGROUND: It has been suggested that the 655 nm InGaAsP diode laser radiation can induce considerably higher amounts of fluorescence in subgingival calculus than in cementum. This in vitro study evaluated the use of fluorescence induced by the diode laser radiation for the detection of subgingival calculus. METHODS: The study sample consisted of 30 extracted molars, premolars, canines, and incisors. The root surface of each sample was partially covered with subgingival calculus. The source of laser radiation was an InGaAsP diode laser emitting visible radiation at a wavelength of 655 nm. The fluorescent radiation reflected from the cementum and calculus was detected by a photoelectric cell integrated within the diagnostic system. The samples were randomly assigned to 3 experimental groups of 10 teeth each for detection of calculus in various media. Specifically, the fluorescence was determined in air (group A), in electrolytic salt solution (group B), and in blood (group C). For each sample, the intensity of the fluorescent light was evaluated separately for cementum and calculus in triplicate measurements. The statistical analysis was performed using a t test at a level of significance of 5% (P<0.05). RESULTS: The intensities of fluorescence radiation emitted by cementum were 0.4 (+/-0.51) in air, 0.4 (+/-0.51) in electrolytic solution, and 2.13 (+/-0.59) in blood. For calculus, the relative intensities of fluorescence radiation were 54.1 (+/-29.09) in air, 60.77 (+/-28.35) in electrolytic salt solution, and 39.63 (+/-29.79) in blood. The differences in fluorescence between cementum and calculus within each experimental unit were significant (group A: P= 0.0002, group B: P= 0.0001, group C: P= 0.031). The intensity of fluorescence in calculus was also significantly different between the 3 experimental groups. CONCLUSION: The present study indicates that subgingival calculus can be reliably detected on extracted teeth using laser fluorescence induced by the 655 nm diode-laser radiation. In vivo studies are necessary to evaluate the clinical utility of this procedure.

Dental Calculus↗