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Biomedical subjects

P G Jost-Brinkmann

Publications and source records attributed to P G Jost-Brinkmann.

At least 19 recordsLinked to original sources
PubMed2003

Clinical measurement of force systems upon activation of transpalatal arch in the treatment of unilateral crossbite.

OBJECTIVES: in this study, forces and moments acting on the molars were theoretically determined by means of small-deflection analysis when an asymmetric third-order activation of the TPA was carried out. MATERIALS AND METHODS: the transpalatal arch (TPA) is used to correct unilateral crossbites through the application of buccal root torque to the anchorage molar and lingual root torque to the contralateral molar in crossbite, combined with expansion. Unfortunately, the complex force systems created at the molars upon activation of the TPA cannot be easily estimated. RESULTS: our computations revealed that the vertical forces developed on the molars when both ends of the TPA are inserted into the lingual sheaths (two-couple system) is four-times greater than those when only one end is tied to the lingual sheath as a single-point contact (one-couple system). CONCLUSIONS: we propose a method of clinical estimation of the force system in a two-couple system by directly measuring the vertical force produced by the one-couple system.

Algorithms↗
PubMed2001

Experimental evaluation of initial tooth displacement, center of resistance, and center of rotation under the influence of an orthodontic force.

The purpose of this study was to determine the location of the center of resistance and the center of rotation of the maxillary central incisors under the influence of a single simple force and to investigate related geometric parameters of the teeth and the surrounding periodontal tissues. By measuring the initial displacement of the central incisors with a magnetic sensing system, the location of the center of resistance and the centers of rotation associated with various forces were determined in 3 human subjects. The results show that the location of the center of resistance of the maxillary central incisor depends on the palatal bone level and is at approximately two-thirds of the palatal alveolar bone height, measured from the root apex. A greater moment-to-force ratio is needed for any controlled movement of the maxillary incisors during retraction in patients with reduced palatal alveolar bone height. This study suggests a method for estimating the location of the center of resistance of a tooth.

Alveolar Bone Loss↗
PubMed2000

Clinical evaluation of a new technique for interdental enamel reduction.

In orthodontics, reduction of tooth-size by grinding interproximal surfaces (stripping) of teeth is a common procedure. In order to achieve perfectly smooth surfaces, clinicians have carefully tested various methods and progressively improved this therapeutic procedure. In this in-vivo study we used scanning electron microscopy (SEM) to evaluate the morphologic effect of a 3-step technique using an oscillating perforated diamond-coated disc for enamel reduction and 2 Sof-Lex XT discs for polishing. This technique was applied in 32 patients with an average age of 15.5 years. A total of 296 interproximal surfaces was treated and replicas were produced for scanning electron microscopy evaluation. The scanning electron microscopy investigations demonstrated that more than 90% of the reproximated surfaces were very well or well polished, resulting in polished enamel surfaces smoother than untreated enamel. This technique proved to be clinically expedient as it finished each interproximal surface within about 2.2 minutes. At the same time, it was demonstrated to be safe and comfortable for the patient, eliminating the need for lip or cheek protectors and making injuries unlikely.

Adolescent↗
PubMed2000

Ultrasonographic measurement of tongue movement during swallowing.

Previous ultrasonographic studies on tongue functions were limited by the possibility of artifacts caused by movement of the submental area during function. Consequently, tongue movements were misinterpreted. A dynamic tongue imaging technique, the cushion-scanning technique, was used to overcome this problem. Later, swallowing was investigated and divided into five phases using cushion-scanning technique-aided M-mode ultrasonograms. In this study, cushion-scanning technique in combination with the B-mode and M-mode ultrasonography was applied to investigate and measure the tongue movement during swallowing in 55 normal persons. The average duration, range of motion and speed of swallowing were found to be 2.43 s, 24.06 mm, and 10.34 mm/s, respectively. The computer-aided B-mode plus M-mode ultrasonography in combination with the cushion-scanning technique is a valuable tool for study of tongue functions.

Adolescent↗
PubMed1999

In-vitro study of resin-modified glass ionomer cements for cementation of orthodontic bands. Isolation, surplus removal and humidity as factors influencing the bond strength between enamel, cement and metal.

The aim of this in vitro study was to investigate different light-cured and chemically cured resin-modified glass ionomer cements used for the cementation of orthodontic bands and to analyze various factors influencing the adhesive strength between enamel, cement and stainless steel. Four resin-modified glass ionomers (Fuji Ortho LC/GC, Fuji Duet/GC, Unitek Multi-Cure Glass Ionomer Orthodontic Band Cement/3M Unitek, Vitremer/3M) and 1 compomer (Band-Lok/Reliance) were examined. Flattened and polished bovine teeth embedded in polyurethane resin were used as enamel specimens. Before cementation, 50% of the specimens were moistened with the aerosol of an inhalation device, while the rest were dried with compressed air. Stainless steel cylinders (CrNi 18 10) were perpendicularly bonded onto the polished enamel using a custom-made cementation device and immediately topped with a pressure of 0.25 MPa. The cement was isolated with either Ketac Glaze/ESPE, Fuji Coat/GC, Cacao Butter/GC, Dryfoil/Jalenko or Final Varnish/VOCO, or was left uncoated. Eight minutes after the beginning of mixing, either the surplus cement was removed with a scalpel or surplus removal was simulated with ultrasound. After 24 hours storage in a water bath at 37 degrees C and 1,000 thermocycles the shear bond strength was determined. Significant differences with respect to the shear bond strength were found among the following cements, ranking from highest to lowest: Fuji Duet, Unitek cement > Fuji Ortho LC > Vitremer > Band-Lok. The application of a barrier coating significantly increased the shear bond strength of all cements except Fuji Ortho LC. The light-cured resin Ketac Glaze proved to be the most effective barrier coating. A dry enamel surface increased the bond strength of all investigated cements except Unitek cement. The use of ultrasound led to no significant reduction in shear bond strength in comparison with surplus removal with a scalpel.

Animals↗
PubMed1999

Shear bond strengths attained in vitro with light-cured glass ionomers vs composite adhesives in bonding ceramic brackets to metal or porcelain.

PURPOSE: The aim of this in vitro study was to evaluate whether light-cured resin-modified glass ionomers provide sufficient bond strength for bonding ceramic brackets to metal and porcelain. In addition, the effect of mechanically retentive vs. silanized bracket bases on shear bond strength was investigated. MATERIALS AND METHODS: Flat specimens made from amalgam, a precious metal alloy, or ceramic were air-abraded with Al2O3 for 3 s and subsequently bonded with either Transcend 6000 or Fascination ceramic brackets. Alternatively, 20 porcelain specimens were treated with 9.6% HF for 2 min. Fuji Ortho LC and Photac Bond (light-cured glass ionomer cements [GIC]) served as adhesives. Two composite adhesives (Concise orthodontic and Transbond) in combination with various conditioners formed the control groups. After water storage for 24 hours, the shear bond strengths of all specimens were determined. RESULTS: Taking 10 MPa as a clinically sufficient bond strength, both resin-modified GICs produced a reliable retention of Transcend 6000 brackets on ceramic and amalgam, while the silanized Fascination brackets yielded a lower shear bond strength. On the precious metal alloy, only Fuji Ortho LC showed adequate strength. Various composite-conditioner combinations produced higher maximum bond strengths than the GICs. The location of bond failure varied considerably, and with most adhesives, bracket fractures occurred occasionally under shear stress. CONCLUSION: The investigated light-cured GICs provide sufficient strength for bonding ceramic brackets, but in terms of bond failure site and bracket fracture, they provide no advantage over composite adhesives.

Ceramics↗
PubMed1998

The influence of air polishers on tooth enamel. An in-vitro study.

This study compares the effect of 4 different air-powder abrasive devices (PWS) (Air-Flow-S1, Clean-Jet, Prophy-Jet 30, Prophy-Unit) on tooth enamel. Freshly extracted bovine teeth were partially embedded in polyurethane, the labial surface ground flat and highly polished. Subsequently the teeth were subjected to the spray from the air-powder abrasive device for 60 s or polished with a prophylactic paste (CCS 170, CCS 250 or Cleanic) for the same length of time. The effects of the different air-powder abrasive systems were tested under multiple adjustments of powder/air and water. In addition the effects of air-powder abrasive systems and prophylactic pastes on several dentin surfaces were measured. The resulting surface textures of the teeth were examined using laser optic profilometry. In this process multiple measurements of roughness as well as tooth erosion were determined. The Clean-Jet led to significantly rougher surfaces than the 3 prophylactic pastes at every setting. The Air-Flow-S1, Prophy-Jet 30 and Prophy-Unit resulted in enamel abrasion that was either less than that caused by the prophylactic pastes or not significantly different at every examined setting. The 3 polishing pastes removed 3.6 microns to 7.2 microns of enamel in 60 s. The Clean-Jet removed significantly more enamel at every setting per unit of time than the prophylactic pastes (up to 0.1 mm/min); therefore routine application of this device is not advised. Enamel abrasion by the Air-Flow-S1, Prophy-Jet 30 and Prophy-Unit was either less than that measured with the prophylactic pastes or not significantly different. However, the Air-Flow-S1 was more abrasive than Cleanic paste at maximum water adjustment. The Air-Flow-S1 removed 641.2 microns/min of dentin compared to 339.6 microns/min by the Prophy-Jet 30.

Air↗
PubMed1998

Effect of air polishing on the fluoride release of (resin-modified) glass ionomer cements and of a polyacid-modified composite resin.

Eight different conventional and resin-modified glass ionomers as well as a polyacid-modified composite were air polished and their fluoride release was determined in comparison to untreated controls. The air polishing was done with two different devices at medium and maximum setting for powder and water. Ninety discs of 1.5 mm thickness and 7.0 mm diameter were produced from each cement. These discs were stored in 5 ml deionized water at 37 degrees C. After 1 day and 1, 4, 8, 12, and 16 weeks, the specimens were transferred into new vials with fresh deionized water. From the 4th week onward, the specimens (except for the untreated controls) were air polished on half of their upper and lower surfaces for 2 s each before being put into a new vial. After 20 weeks the fluoride released during the previous 4 weeks was determined with a fluoride ion-sensitive electrode. With the exception of Ketac-Cem, all cements released significantly more fluoride ions after air polishing, irrespective of the devices' settings. The differences in the amount of fluoride released among the investigated materials were greater than the changes in fluoride release patterns caused by air polishing. Air polishing increased the fluoride release by 20-60% in most of the materials investigated.

Cariostatic Agents↗
PubMed1998

An experimental evaluation of effects and side effects of asymmetric face-bows in the light of in vivo measurements of initial tooth movements.

By using a magnetic sensing system, the translational and rotational molar movements under the application of various asymmetric face-bows were measured two-dimensionally in human subjects to evaluate their primary effects and side effects. The asymmetric face-bow designs tested were three types of power arm face-bows, swivel offset face-bow, and internal hinge face-bow. Although all face-bow designs were considered to be effective in achieving asymmetric distalizations of the molars, they generated lateral displacements that may lead to an undesirable crossbite. The swivel offset face-bow may produce unexpected results and its fabrication is complicated. The internal hinge face-bow is remarkably effective for asymmetric molar distalizations. Unfortunately, it causes a strong crossbite tendency on the molar to be more distalized. Therefore the use of the power arm face-bow is thought to be relatively recommendable because it showed an acceptable asymmetric effect and is easily fabricated from a commercially available face-bow. It is concluded that all asymmetric face-bows generate lateral forces as side effects as long as the force delivery system with a combination of an asymmetric face-bow and a neck strap or head cap is applied. The current study suggests a method whereby the side effect of asymmetric face-bows can be eliminated.

Adult↗
PubMed1998

Shear bond strengths of ceramic brackets bonded with different light-cured glass ionomer cements: an in vitro study.

The purpose of this study was to evaluate the shear bond strengths of four light-cured glass ionomer cements used for direct bonding of ceramic brackets, and to compare the results with a two-paste chemically-cured composite resin. Two commercially available polycrystalline ceramic brackets, with either chemically or mechanically retentive bracket bases, were evaluated. The brackets were bonded to 100 freshly extracted bovine incisors, and, after storage in tap water at room temperature for 24 hours, they were subsequently tested in a shear mode using a universal testing machine. The maximum bond strength and the site of bond failure were recorded. With the mechanically retentive base, Fuji Ortho LC produced the highest bond strength (18.50 MPa), which was not significantly different from the values achieved with Concise (14.88 MPa) (P > 0.1) and Photac Bond (13.86 Mpa) (P = 0.1). The lowest bond strength was provided by locomp A20 (5.23 MPa). With the chemically retentive base, the highest bond strength was measured with Concise (29.27 MPa), which was significantly (P < 0.01) higher than the values for Photac Bond (16.27 MPa) and Fuji Ortho LC (13.48 MPa). Again locomp A20 produced the lowest bond strength (3.21 MPa). Three cements (Dyract Ortho, locomp A20 and Fuji Ortho LC) provided higher shear bond strengths with the mechanical retention system, whereas Concise and Photac Bond gave higher strengths with the silane-treated bracket bases. However, the strengths were statistically significantly different only for locomp A20 (P = 0.001) and Concise (P = 0.001). With the mechanically retentive base, Dyract Ortho and locomp A20 failed at the enamel-adhesive interface, whereas Photac Bond and Concise debonded at the bracket-adhesive interface. Fuji Ortho LC failed at both, the bracket-adhesive (40 per cent) and the adhesive-enamel (60 per cent) interface. With the chemically retentive base, all the adhesives failed at the enamel-adhesive interface. Only one bracket fracture occurred in this study, and no enamel damage was detected.

Acrylic Resins↗
PubMed1998

Effects of saliva and water contamination on the enamel shear bond strength of a light-cured glass ionomer cement.

The purpose of this study was to evaluate the shear bond strengths of Fuji Ortho LC (GC Corp., Tokyo, Japan), a light-cured resin-reinforced glass ionomer, used for direct bonding of stainless steel and ceramic brackets under four different enamel surface conditions: (A) nonconditioned and dry, (B) conditioned with polyacrylic acid and moistened with saliva, (C) conditioned with polyacrylic acid and moistened with water, (D) nonconditioned and wet. Stainless steel lingual buttons and two types of polycrystalline ceramic brackets, with either mechanically or chemically retentive bracket bases, were evaluated. The brackets were bonded to 120 freshly extracted bovine incisors; after storage in tap water at room temperature for 24 hours, they were subsequently tested in a shear mode with a universal testing machine. The maximum bond strength and the site of bond failure were recorded. With stainless steel brackets, subgroup B produced the highest bond strength (23.8 MPa), which was significantly (p < 0.05) higher than all the other enamel conditions tested. With ceramic brackets, the highest bond strengths (20.9 MPa and 25.4 MPa, respectively) were measured with subgroup C. Bond failure analysis revealed that each bracket type failed predominantly at the enamel-adhesive interface, except for Transcend 6000. The results indicate that the shear bond strength of Fuji Ortho LC is significantly enhanced by contaminating the enamel surface with either saliva or water after conditioning, depending on bracket type used. Even water contamination of nonconditioned enamel surfaces does not seem to preclude clinically acceptable bond strengths of both stainless steel and ceramic brackets, allowing, at the same time, a safe debonding without enamel damage.

Acid Etching, Dental↗
PubMed1997

Light-cured glass ionomer cement as a bracket adhesive with different types of enamel conditioners.

Eighty bovine incisors were ground on 320-grit silicone carbide paper and cleaned with fluoride-free prophylaxis paste. The enamel surface conditions were: 1. no conditioning; 2. salicylic acid (10%, 10s); 3. benzoic acid (10%, 10s); 4. air polishing with sodium hydrogen carbonate/Prophy-Jet; 5. Prophy-Jet, followed by polyacrylic acid (PAA, 10%, 10 s); 6. PAA, followed by saliva contamination; 7. PAA; 8. phosphoric acid (37%, 10 s). Fuji Ortho II LC (GC) was used as a bracket adhesive in groups 1 t0 7, and in group 8 Concise orthodontic (3M). Stainless steel lingual buttons were placed by hand. Polymerisation with visible light was carried out 20 s from mesial, distal, incisal and gingival. After 24 h storage in tap water at room temperature the shear bond strengths were tested in accordance with ISO specification TC 106/SC/WG16. Mean values of the groups were compared using Student's t-test. Group 7 (PAA) attained the highest mean shear strength (in comparison with control group): 28 MPa. This was both significantly different from the control group (Concise, 33 MPa) and highly significant in comparison with the other groups (< 16 MPa). The shear bond strength of Fuji Ortho II LC on PAA conditioned enamel indicates the clinical applicability of this material.

Animals↗
PubMed1997

Risk of pulp damage due to temperature increase during thermodebonding of ceramic brackets.

The purpose of this study was to perform in vitro measurements of the temperature increase at the enamel-dentine interface during electrothermal removal of ceramic brackets, and to analyse, in vivo, whether signs of pulp damage can be observed 4 weeks after the procedure. In vitro study: a total of 29 caries-free human teeth were cut into buccal and lingual halves. The buccal halves were bonded with ceramic brackets, and miniature thermocouples were placed from the pulpal side into holes drilled to the enamel-dentine interface under the centre of the bracket slot. From the onset of thermodebonding, the temperature increase relative to room temperature was recorded for a period of 43 seconds. The maximum temperature increase at the enamel-dentine interface was 6.9 degrees C. In vivo study: a total of 12 human premolars scheduled for extraction for orthodontic reasons were bonded with ceramic brackets. Electrothermal debonding was performed the following day. After 4 weeks, the teeth were extracted and prepared for histological examination. Following demineralization, sections were prepared for light microscopic examination. No signs of pulpal inflammation were observed.

Acrylic Resins↗
PubMed1996

In-vitro study of the adhesive strengths of brackets on metals, ceramic and composite. Part 1: Bonding to precious metals and amalgam.

Adult patients often have fillings, artificial crowns and/or bridges that make fitting of conventional bands difficult or even impossible. In such cases bonding rather than banding would be preferable. The present paper presents the investigation of more than 25 resin/conditioner combinations with respect to their bond strength to different metals as well as to amalgam. For that purpose stainless steel lingual buttons were bonded with the various adhesives and their shear bond strengths and types of bond failure were determined after 24 hours. All specimens were air-abraded with 50 microns Al2O3 for 2 or 4 seconds by means of a Microetcher before bonding. For comparison, buttons were also bonded to bovine enamel after air-abrasion or conventional etching with 37% H3PO4. Results show that, on all metals investigated, several materials yield bond strengths which are similar to or higher than what is achieved with the conventional acid etch technique on enamel. Maximum adhesive strength is not always desirable, however, for bonding brackets. The type of bond failure and the risk of irreversible damage to the bonded material have also to be taken into consideration. Al2O3 abrasion may cause considerable damage to enamel within 4 seconds. Since the bond strength on air-abraded enamel is about the same as on acid etched enamel, conventional etching with H3PO4 is preferable to the sandblasting of enamel.

Acid Etching, Dental↗
PubMed1996

In-vitro study of the adhesive strengths of brackets on metals, ceramic and composite. Part 2: Bonding to porcelain and composite resin.

In addition to part 1 of the study, the present paper investigated more than 25 resin/conditioner combinations with respect to their bond strengths to porcelain and composite resin. For that purpose stainless steel lingual buttons were bonded with the various adhesives and their shear bond strengths and types of bond failure were determined after 24 hours. All specimens were air-abraded with 50 microns Al2O3 for 2 or 4 seconds by means of a Microetcher before bonding. Results show that, on the porcelain, and composite under investigation, several materials yield bond strengths which are similar to or higher than what is achieved with the conventional acid etch technique on enamel. Maximum adhesive strength is not always desirable, however, for bonding brackets. The type of bond failure and the risk of irreversible damage to the bonded material have also to be taken into consideration.

Acid Etching, Dental↗
PubMed1996

Effectiveness of three different types of electric toothbrushes compared with a manual technique in orthodontic patients.

Patients undergoing orthodontic treatment with fixed appliances are at risk of developing carious white spot lesions and gingival inflammation because of the challenge of oral hygiene. The purpose of this study was to evaluate under home conditions the effectiveness of three different types of electric toothbrushes during active appliance therapy: Interplak (Bausch & Lomb, Berlin, Germany), Rota-dent (Rota-dent, Kusnacht, Switzerland), and Braun Oral-B Plaque Remover (Braun/Oral-B, Kronberg, Germany). A manual technique, which included normal toothbrush, interdental brush, and dental floss, served as reference. The study was structured as a single-blind "Latin square design" study. Thirty-eight orthodontic patients were randomly allocated to groups who, within the test period, alternately used the toothbrushes. Before getting a new toothbrush that was to be used for a period of 4 weeks, each patient received video and written instructions. For another 4 weeks, the patient returned to the usual oral hygiene procedures before receiving the next new toothbrush. Oral hygiene was evaluated at the start of a new test period and after 2 and 4 weeks. Clinical scores included a modified O'Leary Plaque Index and Ainamo Gingival Bleeding Index. Wilcoxon rank testing for aggregated surfaces revealed statistically significantly lower plaque scores for Rota-dent than for the manual technique (p < 0.01). For all other toothbrushes, no differences were found in comparison to the manual technique. For Plaque Indices of specific sites, statistical analysis revealed all electric toothbrushes to be equal to the manual technique. No differences in Gingival Bleeding Indices were found after 4 weeks with either toothbrush. Patients with poor oral hygiene who used Rota-dent and Braun Oral-B Plaque Remover OD5 had statistically significantly lower plaque scores compared with the manual technique (p < 0.01; p < 0.05); for patients with good oral hygiene, these differences were neutralized. It may be concluded that electric toothbrushes of the new generation are a real alternative to the often laborious manual tooth cleaning procedures used during active appliance therapy. Patients with poor oral hygiene may benefit from them especially because plaque removal can be achieved easier and faster.

Adolescent↗
PubMed1996

The cushion scanning technique: a method of dynamic tongue sonography and its comparison with the transducer-skin coupling scanning technique during swallowing.

RATIONALE AND OBJECTIVES: We describe the cushion scanning technique (CST), which solves common difficulties encountered during ultrasound investigations of swallowing. These problems arise when the transducer is held in direct contact with the submental area. Some of these problems include movements of the ultrasound transducer during swallowing and compression of the submental region, which causes abnormal swallowing patterns. METHODS: To compare ultrasound images produced with the conventional hand-held transducer-skin coupling scanning technique with the CST, we studied five participants with no clinical signs of tongue dysfunction. All tongue movements were recorded by real-time B+M-mode sonography. RESULTS: Images produced with the hand-held transducer were found to be unstable because the transducer moved during swallowing, thereby changing the scanning section. By contrast, the transducer and the participant's head remained in a constant position throughout the CST trial. There was no obvious compression of the submental muscles. CONCLUSION: The CST allows for a better intraindividual reproducibility of the swallowing pattern and for a more standardized and objective ultrasound examination than the hand-held transducer-skin coupling scanning technique.

Adult↗