Journal of orofacial orthopedics = Fortschritte der Kieferorthopadie : Organ/official journal Deutsche Gesellschaft fur Kieferorthopadie, Jan 24, 2016
Orthodontic appliances are considered to be highly biocompatible although adverse effects attribu... more Orthodontic appliances are considered to be highly biocompatible although adverse effects attributed to the release of nickel ions (Ni(2+)) have been documented. Self-ligating brackets have grown in popularity for economic reasons and supposed friction reduction. The aim of the present prospective cohort study was therefore to determine salivary Ni(2+) concentrations in patients undergoing orthodontic treatment with self-ligating fixed appliances. A group of 30 patients between 10 and 13 years of age were treated with self-ligating brackets (SmartClip™), molar bands, and nickel-titanium (NiTi) archwires. Unstimulated saliva samples were collected after different time points (before treatment, after self-ligating bracket and band placement, before archwire insertion, after archwire insertion, and finally 4 and 8 weeks afterwards) and analyzed with an ICP mass spectrometer followed by generalized estimating equation modelling with α = 5 %. The baseline median salivary Ni(2+) concentra...
The objective of this study was to investigate whether the response to periodontal treatment diff... more The objective of this study was to investigate whether the response to periodontal treatment differs among obese, overweight or normal-weight patients. Both randomized and non-randomized studies were identified from searches up to July 2013. Risk of bias was assessed with the Downs-Black checklist, the Cochrane tool and the GRADE framework. Quantitative synthesis was conducted with random-effects meta-analyses in subgroups for systemically healthy and diabetic patients. A total of 15 studies including 867 patients were included. No significant difference was found for any clinical periodontal parameter between overweight/obese and normal-weight patients. Periodontal treatment in systemically healthy overweight/obese patients was associated with higher decrease in TNFα levels (1 study) and higher decrease in HbA1c levels (1 study) compared to systemically healthy normal-weight patients. Contrary to diabetic normal-weight patients, periodontal treatment in diabetic overweight/obese pa...
American Journal of Orthodontics and Dentofacial Orthopedics, 1988
Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evalua... more Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evaluated with the scanning electron microscope (SEM). Even under in vitro conditions with the finest finishing strips, it was not possible to produce an enamel surface free of the furrows that result from the initial abrasion caused by the coarse strip. Enamel surfaces stripped gradually from coarse to superfine were left in the mouths of patients for 12 weeks and evaluated with the SEM. The edges of the furrows were found to be smoother but the furrows remained wide and deep enough to facilitate more plaque accumulations than those on untreated surfaces. The use of dental floss did not result in prevention of plaque accumulations along the bottom of the furrows.
Chronic periodontitis (CP) is a prevalent pathogen-associated inflammatory disorder characterized... more Chronic periodontitis (CP) is a prevalent pathogen-associated inflammatory disorder characterized by the destruction of tooth-supporting tissues, and linked to several systemic diseases. Both the periodontopathogen Porphyromonas gingivalis (Pg), and the genetically determined host immune response, are hypothesized to play a crucial role in this association. To identify new target genes for CP and its associated systemic diseases, we investigated the transcriptome induced by Pg in human monocytes using a genome-wide approach. Monocytes were isolated from healthy male volunteers of European origin and challenged with the Pg virulence factor LPS. Array-based gene expression analysis comprising >47,000 transcripts was performed followed by pathway analyses. Transcriptional data were validated by protein and cell surface markers. LPS Pg challenge led to the significant induction of 902 transcripts. Besides known periodontitis-associated targets, several new candidates were identified ...
The contours of the eminence and the fossa of the temporomandibular joint (TMJ) of Cercopithecus ... more The contours of the eminence and the fossa of the temporomandibular joint (TMJ) of Cercopithecus aethiops, a monkey species, are analyzed in sagittal-vertical sections. The functionally relevant contours can be approximated by catenates for both the eminence as the protrusive guidance and the fossa as the retrusive guidance. This study reveals the more general character of the contour formula y = a cosh(x/a) - a. This may be true because all these catenates are similar to one another and since they can be found in the guiding contours of the components of the stomatognatic system in man as well as in Cercopithecus aethiops.
Informationen aus Orthodontie & Kieferorthopädie
Biomechanical analysis of the stomatognathic system yields that the linkage between posterior and... more Biomechanical analysis of the stomatognathic system yields that the linkage between posterior and anterior guidance can be modelled by a link quadrangle (throttle crank) with closed linkage. Within this gear system the biochemical ideal position of the couple-line (functional length of the mandible) possesses a special meaning in centric occlusion: Along this line the gear system can be stretched without altering its essential mechanical properties. Interindividual comparison of the arrangement of mandibulary and maxillary structures related to the ideal initial position of the couple-line presents interindividual constants of arrangement and of growth. It is possible to define an individual, non-orthogonal system of coordinates. Its origin represents the individual center of growth. During growth special skeletally defined points run along radius vectors of this center. The rate of growth can depend on the angle between radius vector and couple-line.
ABSTRACT Die inhaltlichen Zusammenhänge zwischen den Fächern Kieferorthopädie und Parodontologie ... more ABSTRACT Die inhaltlichen Zusammenhänge zwischen den Fächern Kieferorthopädie und Parodontologie sind mannigfaltig. Zum einen werden die Auswirkungen einer kieferorthopädischen Bewegung von Zähnen sowohl im Sinne einer möglichen Schädigung, aber auch im Sinne einer Verbesserung bezüglich der langfristigen Gesundheit der Parodontalgewebe diskutiert. Andererseits ist die kieferorthopädische Behandlung von erwachsenen Patienten auch bei einer Vorschädigung der parodontalen Gewebe heutzutage eine klinische Routinemaßnahme. In Anbetracht der schnellen Entwicklung beider Fächer stellt sich jedoch regelmäßig die Frage nach aktuellen evidenzbasierte Konzepten für diesen interdisziplinären Bereich. Ziel dieser Arbeit ist es, aktuelle Aspekte in der interdisziplinären Therapie zu diskutieren und den derzeitigen Stand der Forschung wiederzugeben. Weiterhin wird ein Therapieschema vorgestellt, welches die Koordination einer kieferorthopädischen Therapie parodontal erkrankter Patienten erleichtern soll.
In the present study we examined the long term influence of orthodontic mandibular arch expansion... more In the present study we examined the long term influence of orthodontic mandibular arch expansion therapy on the periodontal condition of the posterior teeth. 11 years after the end of treatment 31 former patients of our clinic were compared with a control group of matched age and sex distribution. Although we found some additional loss of periodontal attachment for the treated group this differences were not considered to be of clinical significance. Within the treated group the stability of the orthodontic treatment result seemed to be correlated with more favourable periodontal conditions.
Objectives: Hypoxia is an important cellular stress factor in the periodontium, which is related ... more Objectives: Hypoxia is an important cellular stress factor in the periodontium, which is related to smoking, systemic diseases or mechanical loading. Hypoxia inducible factors (HIFs), like HIF-1α, mediate adaptive responses to reduced oxygen availability and, by nuclear translocation and protein stabilization, regulate different HIF-responsive genes, e.g. for angiogenesis, growth and proliferation. The occurrence and probable function of HIF-1α in the periodontal ligament (PDL) under hypoxic and mechanical stress was investigated. Methods: Human PDL cells from healthy premolars were cultured under 3% O2 at 37C for 24 and 48 h and 3 weeks. After harvesting, expression of HIF-1α, proliferating cell nuclear antigen (PCNA) and Vascular Endothelial Growth Factor (VEGF) were detected by RT-PCR, and HIF-1α immunofluorescence staining was done. In a rat model of experimentally induced orthodontic tooth movement of the first maxillary molar after loading different constant and intermittent f...
The aim of this study was to compare the use of odds ratio (OR), risk ratio (RR), and risk differ... more The aim of this study was to compare the use of odds ratio (OR), risk ratio (RR), and risk difference (RD) in meta-analyses of dichotomous outcomes and assess their influence on their results. Initially, we included meta-analyses from a meta-epidemiologic database and reanalyzed them with OR, RR, and RD as summary metric. The primary outcomes were the effects of metric choice on the (1) statistical significance, (2) heterogeneity, and (3) Egger's test for publication bias. Additionally, meta-analyses that originally used OR were reanalyzed using RR to assess the differences in their results. In the 235 meta-analyses (147 reviews) that were included, the conclusions in terms of significance rarely changed. On the other hand, use of OR displayed the lowest I(2) values (median 42%), followed by RR (+5.1%) and RD (+15.0%). The Egger's test was most often significant with RR (32%), followed by RD (29%) and OR (24%). Substitution of RR for OR led to a change of the observed effect...
Obesity is increasing throughout the globe and characterized by excess adipose tissue, which repr... more Obesity is increasing throughout the globe and characterized by excess adipose tissue, which represents a complex endocrine organ. Adipose tissue secrets bioactive molecules called adipokines, which act at endocrine, paracrine, and autocrine levels. Obesity has recently been shown to be associated with periodontitis, a disease characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium, and also with compromised periodontal healing. Although the underlying mechanisms for these associations are not clear yet, increased levels of proinflammatory adipokines, such as leptin, as found in obese individuals, might be a critical pathomechanistic link. The objective of this study was to examine the impact of leptin on the regenerative capacity of human periodontal ligament (PDL) cells and also to study the local leptin production by these cells. Leptin caused a significant downregulation of growth (TGFβ1, and VEGFA) and transcription (RUNX2) factors a...
American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics, 2015
Our objective was to investigate the effect of archwire cross-section increases on the levels of ... more Our objective was to investigate the effect of archwire cross-section increases on the levels of force applied to teeth during complex malalignment correction with various archwire-bracket combinations using an experimental biomechanical setup. The study comprised 3 types of orthodontic brackets: (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip, a passive self-ligating bracket [3M Unitek]; and Time3 [Rocky Mountain Orthodontics, Denver, Colo] and SPEED [Strite Industries, Cambridge, Ontario, Canada], both active self-ligating brackets), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]). All brackets had a nominal 0.022-in slot size. The brackets were combined with 0.014-in and 0.016-in titanium memory wires, Therma-Ti archwires (American Orthodontics, Sheboygan, Wis). The archwires were tied to the conventional brackets ...
Technology and health care : official journal of the European Society for Engineering and Medicine, 1994
A device for quantitative morphometric analysis of tissue alterations caused by laser or electros... more A device for quantitative morphometric analysis of tissue alterations caused by laser or electrosurgery was developed. The unit was designed for interactive evaluation of histological specimens obtained by experimental surgery. It consists of a microscope, a stepper-motor driven scanning stage, a digitizing tablet and a PC with software developed for this purpose. The depth of the incision, the width and the area of the coagulation zone can be measured independent of the microscopic magnification. Graphs and data can be exported in standard data-formats (ASCII, HPGL, DXF) for further processing. The application is demonstrated on experimental incisions with a CO2-laser in the oral mucosa of pigs; quantitative data are presented.
A knowledge of the mechanical processes triggered in the bone and periodontal ligament (PDL) by o... more A knowledge of the mechanical processes triggered in the bone and periodontal ligament (PDL) by orthodontic forces applied to a tooth is of decisive importance for an understanding of the subsequent remodelling around the tooth. To investigate these mechanical relationships, three-dimensional finite element (FE) models of the first lower molar in the rat were established. On the basis of digitized serial histological sections, these FE models were generated semi-automatically. Using various simplified geometrical variations, an appropriate FE model for the analysis of the stress and strain distributions was established. The numerical analyses were carried out under a mesially directed force of 0.1 N. Stress distributions in the bone and PDL showed a similar pattern, while strains in the bone were lower than in the PDL by a factor of 10-5. The data confirm the assumption that strain patterns in the PDL may be the key stimulus of bone remodelling.
The use of suitable orthodontic devices producing desired defined force systems is of importance ... more The use of suitable orthodontic devices producing desired defined force systems is of importance for successful orthodontic treatment. Bending loops can be difficult and time-consuming. Computerised fabrication would enable very precise reproduction of individual loops. A bending machine has now been developed within the framework of a computer-assisted treatment concept. In this study, a prototype machine was used to fabricate U-, T- and delta loops made of stainless steel, cobalt chromium and titanium molybdenum wire. The various geometric parameters of each loop were measured to determine how precisely they had been produced. Furthermore, the force system of each loop were experimentally investigated during simulated activation in an orthodontic measurement and simulation system. The results indicate that the geometric parameters had an average error of 2.8 degrees for angles and 0.9 mm for lengths. Owing to the fabrication errors, loops of the same type produced different force ...
Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft, 2013
The periodontal ligament (PDL) is a connective tissue surrounding the tooth root and attaching it... more The periodontal ligament (PDL) is a connective tissue surrounding the tooth root and attaching it to its bony socket. Being the predominant cell type of this connective tissue, PDL fibroblasts are thought to be responsible for PDL homeostasis and regeneration. Autofluorescence is found in abundant natural substances and many cells exhibit some intrinsic level of autofluorescence depending on the cell type and function. Thus, autofluorescence often makes immunofluorescence staining and flow cytometric analysis difficult. Therefore, in the present study, we have investigated the autofluorescent characteristics of human periodontal ligament (PDL) cells and compared them to cells of epithelial and mesenchymal origin. The results of fluorescence immunostaining and flow cytometric analysis revealed that PDL cells exhibit an extremely high level of autofluorescence in the short wave length region including FITC emission spectra which exceeded those of HEK293 cells, oral keratinocytes and M...
Nickel (Ni) is one of the main metal elements in orthodontic and prosthetic devices. Different ef... more Nickel (Ni) is one of the main metal elements in orthodontic and prosthetic devices. Different effects of Ni are described ranging from an induction of local inflammation to allergy and cancerous/mutagenic properties. Inflammatory reactions are frequently observed in the oral cavity, but the interrelationship of Ni with those events is still unknown. Therefore, we focused on the impact of Ni on inflammation in vitro. In accordance to previous immersion tests of our lab, human gingival fibroblasts (HGFs) (n=6) were exposed to a pro-inflammatory environment using interleukin-1 beta (IL-1β) and additionally stimulated with different Ni(II) concentrations (400 and 4000ng/ml). At varying time points the expression of pro- and anti-inflammatory as well as matrix degeneration proteins, i.e. MMPs, were analyzed. Furthermore, proliferation assays, wound healing tests and the detection of NF-κB activation were conducted. Unstimulated HGFs served as control. Our experiments showed that low clinical average Ni(II) levels did not alter pro-inflammatory cytokines significantly compared to control (p>0.05). Instead, a 10-fold higher dose up-regulated these mediators significantly in a time-dependent manner (p<0.01). This was even more pronounced combining both Ni(II) concentrations with an inflammatory condition (p<0.001), MMP expressions were in line with our findings (p<0.001). The mRNA data were supported by proliferation and wound closure assays (p<0.001). However, the combination of both stimuli induced contradictory results. Analyzing NF-κB activation revealed that our results may be in part attributed to NF-κB. Our in vitro study implicated that Ni(II) has various modifying effects on IL-1β-induced inflammatory processes depending on the concentration.
Journal of orofacial orthopedics = Fortschritte der Kieferorthopadie : Organ/official journal Deutsche Gesellschaft fur Kieferorthopadie, Jan 24, 2016
Orthodontic appliances are considered to be highly biocompatible although adverse effects attribu... more Orthodontic appliances are considered to be highly biocompatible although adverse effects attributed to the release of nickel ions (Ni(2+)) have been documented. Self-ligating brackets have grown in popularity for economic reasons and supposed friction reduction. The aim of the present prospective cohort study was therefore to determine salivary Ni(2+) concentrations in patients undergoing orthodontic treatment with self-ligating fixed appliances. A group of 30 patients between 10 and 13 years of age were treated with self-ligating brackets (SmartClip™), molar bands, and nickel-titanium (NiTi) archwires. Unstimulated saliva samples were collected after different time points (before treatment, after self-ligating bracket and band placement, before archwire insertion, after archwire insertion, and finally 4 and 8 weeks afterwards) and analyzed with an ICP mass spectrometer followed by generalized estimating equation modelling with α = 5 %. The baseline median salivary Ni(2+) concentra...
The objective of this study was to investigate whether the response to periodontal treatment diff... more The objective of this study was to investigate whether the response to periodontal treatment differs among obese, overweight or normal-weight patients. Both randomized and non-randomized studies were identified from searches up to July 2013. Risk of bias was assessed with the Downs-Black checklist, the Cochrane tool and the GRADE framework. Quantitative synthesis was conducted with random-effects meta-analyses in subgroups for systemically healthy and diabetic patients. A total of 15 studies including 867 patients were included. No significant difference was found for any clinical periodontal parameter between overweight/obese and normal-weight patients. Periodontal treatment in systemically healthy overweight/obese patients was associated with higher decrease in TNFα levels (1 study) and higher decrease in HbA1c levels (1 study) compared to systemically healthy normal-weight patients. Contrary to diabetic normal-weight patients, periodontal treatment in diabetic overweight/obese pa...
American Journal of Orthodontics and Dentofacial Orthopedics, 1988
Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evalua... more Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evaluated with the scanning electron microscope (SEM). Even under in vitro conditions with the finest finishing strips, it was not possible to produce an enamel surface free of the furrows that result from the initial abrasion caused by the coarse strip. Enamel surfaces stripped gradually from coarse to superfine were left in the mouths of patients for 12 weeks and evaluated with the SEM. The edges of the furrows were found to be smoother but the furrows remained wide and deep enough to facilitate more plaque accumulations than those on untreated surfaces. The use of dental floss did not result in prevention of plaque accumulations along the bottom of the furrows.
Chronic periodontitis (CP) is a prevalent pathogen-associated inflammatory disorder characterized... more Chronic periodontitis (CP) is a prevalent pathogen-associated inflammatory disorder characterized by the destruction of tooth-supporting tissues, and linked to several systemic diseases. Both the periodontopathogen Porphyromonas gingivalis (Pg), and the genetically determined host immune response, are hypothesized to play a crucial role in this association. To identify new target genes for CP and its associated systemic diseases, we investigated the transcriptome induced by Pg in human monocytes using a genome-wide approach. Monocytes were isolated from healthy male volunteers of European origin and challenged with the Pg virulence factor LPS. Array-based gene expression analysis comprising >47,000 transcripts was performed followed by pathway analyses. Transcriptional data were validated by protein and cell surface markers. LPS Pg challenge led to the significant induction of 902 transcripts. Besides known periodontitis-associated targets, several new candidates were identified ...
The contours of the eminence and the fossa of the temporomandibular joint (TMJ) of Cercopithecus ... more The contours of the eminence and the fossa of the temporomandibular joint (TMJ) of Cercopithecus aethiops, a monkey species, are analyzed in sagittal-vertical sections. The functionally relevant contours can be approximated by catenates for both the eminence as the protrusive guidance and the fossa as the retrusive guidance. This study reveals the more general character of the contour formula y = a cosh(x/a) - a. This may be true because all these catenates are similar to one another and since they can be found in the guiding contours of the components of the stomatognatic system in man as well as in Cercopithecus aethiops.
Informationen aus Orthodontie & Kieferorthopädie
Biomechanical analysis of the stomatognathic system yields that the linkage between posterior and... more Biomechanical analysis of the stomatognathic system yields that the linkage between posterior and anterior guidance can be modelled by a link quadrangle (throttle crank) with closed linkage. Within this gear system the biochemical ideal position of the couple-line (functional length of the mandible) possesses a special meaning in centric occlusion: Along this line the gear system can be stretched without altering its essential mechanical properties. Interindividual comparison of the arrangement of mandibulary and maxillary structures related to the ideal initial position of the couple-line presents interindividual constants of arrangement and of growth. It is possible to define an individual, non-orthogonal system of coordinates. Its origin represents the individual center of growth. During growth special skeletally defined points run along radius vectors of this center. The rate of growth can depend on the angle between radius vector and couple-line.
ABSTRACT Die inhaltlichen Zusammenhänge zwischen den Fächern Kieferorthopädie und Parodontologie ... more ABSTRACT Die inhaltlichen Zusammenhänge zwischen den Fächern Kieferorthopädie und Parodontologie sind mannigfaltig. Zum einen werden die Auswirkungen einer kieferorthopädischen Bewegung von Zähnen sowohl im Sinne einer möglichen Schädigung, aber auch im Sinne einer Verbesserung bezüglich der langfristigen Gesundheit der Parodontalgewebe diskutiert. Andererseits ist die kieferorthopädische Behandlung von erwachsenen Patienten auch bei einer Vorschädigung der parodontalen Gewebe heutzutage eine klinische Routinemaßnahme. In Anbetracht der schnellen Entwicklung beider Fächer stellt sich jedoch regelmäßig die Frage nach aktuellen evidenzbasierte Konzepten für diesen interdisziplinären Bereich. Ziel dieser Arbeit ist es, aktuelle Aspekte in der interdisziplinären Therapie zu diskutieren und den derzeitigen Stand der Forschung wiederzugeben. Weiterhin wird ein Therapieschema vorgestellt, welches die Koordination einer kieferorthopädischen Therapie parodontal erkrankter Patienten erleichtern soll.
In the present study we examined the long term influence of orthodontic mandibular arch expansion... more In the present study we examined the long term influence of orthodontic mandibular arch expansion therapy on the periodontal condition of the posterior teeth. 11 years after the end of treatment 31 former patients of our clinic were compared with a control group of matched age and sex distribution. Although we found some additional loss of periodontal attachment for the treated group this differences were not considered to be of clinical significance. Within the treated group the stability of the orthodontic treatment result seemed to be correlated with more favourable periodontal conditions.
Objectives: Hypoxia is an important cellular stress factor in the periodontium, which is related ... more Objectives: Hypoxia is an important cellular stress factor in the periodontium, which is related to smoking, systemic diseases or mechanical loading. Hypoxia inducible factors (HIFs), like HIF-1α, mediate adaptive responses to reduced oxygen availability and, by nuclear translocation and protein stabilization, regulate different HIF-responsive genes, e.g. for angiogenesis, growth and proliferation. The occurrence and probable function of HIF-1α in the periodontal ligament (PDL) under hypoxic and mechanical stress was investigated. Methods: Human PDL cells from healthy premolars were cultured under 3% O2 at 37C for 24 and 48 h and 3 weeks. After harvesting, expression of HIF-1α, proliferating cell nuclear antigen (PCNA) and Vascular Endothelial Growth Factor (VEGF) were detected by RT-PCR, and HIF-1α immunofluorescence staining was done. In a rat model of experimentally induced orthodontic tooth movement of the first maxillary molar after loading different constant and intermittent f...
The aim of this study was to compare the use of odds ratio (OR), risk ratio (RR), and risk differ... more The aim of this study was to compare the use of odds ratio (OR), risk ratio (RR), and risk difference (RD) in meta-analyses of dichotomous outcomes and assess their influence on their results. Initially, we included meta-analyses from a meta-epidemiologic database and reanalyzed them with OR, RR, and RD as summary metric. The primary outcomes were the effects of metric choice on the (1) statistical significance, (2) heterogeneity, and (3) Egger's test for publication bias. Additionally, meta-analyses that originally used OR were reanalyzed using RR to assess the differences in their results. In the 235 meta-analyses (147 reviews) that were included, the conclusions in terms of significance rarely changed. On the other hand, use of OR displayed the lowest I(2) values (median 42%), followed by RR (+5.1%) and RD (+15.0%). The Egger's test was most often significant with RR (32%), followed by RD (29%) and OR (24%). Substitution of RR for OR led to a change of the observed effect...
Obesity is increasing throughout the globe and characterized by excess adipose tissue, which repr... more Obesity is increasing throughout the globe and characterized by excess adipose tissue, which represents a complex endocrine organ. Adipose tissue secrets bioactive molecules called adipokines, which act at endocrine, paracrine, and autocrine levels. Obesity has recently been shown to be associated with periodontitis, a disease characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium, and also with compromised periodontal healing. Although the underlying mechanisms for these associations are not clear yet, increased levels of proinflammatory adipokines, such as leptin, as found in obese individuals, might be a critical pathomechanistic link. The objective of this study was to examine the impact of leptin on the regenerative capacity of human periodontal ligament (PDL) cells and also to study the local leptin production by these cells. Leptin caused a significant downregulation of growth (TGFβ1, and VEGFA) and transcription (RUNX2) factors a...
American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics, 2015
Our objective was to investigate the effect of archwire cross-section increases on the levels of ... more Our objective was to investigate the effect of archwire cross-section increases on the levels of force applied to teeth during complex malalignment correction with various archwire-bracket combinations using an experimental biomechanical setup. The study comprised 3 types of orthodontic brackets: (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif] and Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo]), (2) self-ligating brackets (SmartClip, a passive self-ligating bracket [3M Unitek]; and Time3 [Rocky Mountain Orthodontics, Denver, Colo] and SPEED [Strite Industries, Cambridge, Ontario, Canada], both active self-ligating brackets), and (3) a conventional low-friction bracket (Synergy [Rocky Mountain Orthodontics]). All brackets had a nominal 0.022-in slot size. The brackets were combined with 0.014-in and 0.016-in titanium memory wires, Therma-Ti archwires (American Orthodontics, Sheboygan, Wis). The archwires were tied to the conventional brackets ...
Technology and health care : official journal of the European Society for Engineering and Medicine, 1994
A device for quantitative morphometric analysis of tissue alterations caused by laser or electros... more A device for quantitative morphometric analysis of tissue alterations caused by laser or electrosurgery was developed. The unit was designed for interactive evaluation of histological specimens obtained by experimental surgery. It consists of a microscope, a stepper-motor driven scanning stage, a digitizing tablet and a PC with software developed for this purpose. The depth of the incision, the width and the area of the coagulation zone can be measured independent of the microscopic magnification. Graphs and data can be exported in standard data-formats (ASCII, HPGL, DXF) for further processing. The application is demonstrated on experimental incisions with a CO2-laser in the oral mucosa of pigs; quantitative data are presented.
A knowledge of the mechanical processes triggered in the bone and periodontal ligament (PDL) by o... more A knowledge of the mechanical processes triggered in the bone and periodontal ligament (PDL) by orthodontic forces applied to a tooth is of decisive importance for an understanding of the subsequent remodelling around the tooth. To investigate these mechanical relationships, three-dimensional finite element (FE) models of the first lower molar in the rat were established. On the basis of digitized serial histological sections, these FE models were generated semi-automatically. Using various simplified geometrical variations, an appropriate FE model for the analysis of the stress and strain distributions was established. The numerical analyses were carried out under a mesially directed force of 0.1 N. Stress distributions in the bone and PDL showed a similar pattern, while strains in the bone were lower than in the PDL by a factor of 10-5. The data confirm the assumption that strain patterns in the PDL may be the key stimulus of bone remodelling.
The use of suitable orthodontic devices producing desired defined force systems is of importance ... more The use of suitable orthodontic devices producing desired defined force systems is of importance for successful orthodontic treatment. Bending loops can be difficult and time-consuming. Computerised fabrication would enable very precise reproduction of individual loops. A bending machine has now been developed within the framework of a computer-assisted treatment concept. In this study, a prototype machine was used to fabricate U-, T- and delta loops made of stainless steel, cobalt chromium and titanium molybdenum wire. The various geometric parameters of each loop were measured to determine how precisely they had been produced. Furthermore, the force system of each loop were experimentally investigated during simulated activation in an orthodontic measurement and simulation system. The results indicate that the geometric parameters had an average error of 2.8 degrees for angles and 0.9 mm for lengths. Owing to the fabrication errors, loops of the same type produced different force ...
Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft, 2013
The periodontal ligament (PDL) is a connective tissue surrounding the tooth root and attaching it... more The periodontal ligament (PDL) is a connective tissue surrounding the tooth root and attaching it to its bony socket. Being the predominant cell type of this connective tissue, PDL fibroblasts are thought to be responsible for PDL homeostasis and regeneration. Autofluorescence is found in abundant natural substances and many cells exhibit some intrinsic level of autofluorescence depending on the cell type and function. Thus, autofluorescence often makes immunofluorescence staining and flow cytometric analysis difficult. Therefore, in the present study, we have investigated the autofluorescent characteristics of human periodontal ligament (PDL) cells and compared them to cells of epithelial and mesenchymal origin. The results of fluorescence immunostaining and flow cytometric analysis revealed that PDL cells exhibit an extremely high level of autofluorescence in the short wave length region including FITC emission spectra which exceeded those of HEK293 cells, oral keratinocytes and M...
Nickel (Ni) is one of the main metal elements in orthodontic and prosthetic devices. Different ef... more Nickel (Ni) is one of the main metal elements in orthodontic and prosthetic devices. Different effects of Ni are described ranging from an induction of local inflammation to allergy and cancerous/mutagenic properties. Inflammatory reactions are frequently observed in the oral cavity, but the interrelationship of Ni with those events is still unknown. Therefore, we focused on the impact of Ni on inflammation in vitro. In accordance to previous immersion tests of our lab, human gingival fibroblasts (HGFs) (n=6) were exposed to a pro-inflammatory environment using interleukin-1 beta (IL-1β) and additionally stimulated with different Ni(II) concentrations (400 and 4000ng/ml). At varying time points the expression of pro- and anti-inflammatory as well as matrix degeneration proteins, i.e. MMPs, were analyzed. Furthermore, proliferation assays, wound healing tests and the detection of NF-κB activation were conducted. Unstimulated HGFs served as control. Our experiments showed that low clinical average Ni(II) levels did not alter pro-inflammatory cytokines significantly compared to control (p>0.05). Instead, a 10-fold higher dose up-regulated these mediators significantly in a time-dependent manner (p<0.01). This was even more pronounced combining both Ni(II) concentrations with an inflammatory condition (p<0.001), MMP expressions were in line with our findings (p<0.001). The mRNA data were supported by proliferation and wound closure assays (p<0.001). However, the combination of both stimuli induced contradictory results. Analyzing NF-κB activation revealed that our results may be in part attributed to NF-κB. Our in vitro study implicated that Ni(II) has various modifying effects on IL-1β-induced inflammatory processes depending on the concentration.
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Papers by Prof. Dr. Andreas Jäger