Andrej Zentner

Surgically assisted rapid palatal expansion. An acoustic rhinometric, morphometric and sonographic investigation.

This study aimed to evaluate the effect of surgically assisted rapid palatal expansion on the skeletal structures of the midface.Ten patients (mean age 28.5 years) were investigated by means of acoustic rhinometry, study model analysis and sonography before and after the procedure of surgically assisted rapid palatal expansion.The measurements revealed that surgically assisted rapid palatal expansion not only resulted in transverse expansion of the maxilla, providing dental arch space for lining up the teeth; the procedure also caused a substantial enlargement of the maxillary apical base and of the palatal vault, providing space for the tongue for correct swallowing and thus preventing relaps. There was a distinct subjective improvement in nasal breathing associated with enlargement of the nasal valve towards normal values and with an increase of nasal volume in all compartments.The measurements showed a marked influence of surgically assisted rapid palatal expansion on the skeletal structures of the midface. The significant widening can be demonstrated by non-invasive examination. Success of the osteotomy procedure can be readily monitored by sonographic examination of the expansion and the subsequent ossification, which allows individually adjusted retention periods and avoids frequent radiation exposure.ZusammenfassungIn der vorliegenden Untersuchung sollten die Auswirkungen der chirurgisch unterstützten Gaumennahterweiterung auf dentoalveoläre, maxillär-basale und nasale Strukturen des Gesichtsschädels mit nicht invasiven Untersuchungstechniken evaluiert werden.Dazu wurden zehn erwachsene Patienten vor und nach chirurgisch unterstützter Gaumennahterweiterung mittels reflexionsakustischer Rhinometrie, Modellanalyse und Sonographie untersucht.Es zeigte sich, dass die chirurgisch unterstützte Gaumennahterweiterung auch beim erwachsenen Patienten nicht nur zu einer transversalen dentoalveolären Dehnung des Oberkiefers (Platz im Zahnbogen zur Ausrichtung der Zähne) führt, sondern auch die apikale Oberkieferbasis und das Gaumenvolumen (Platz für die Zunge beim regelrechten Schlucken und damit Rezidivprophylaxe) werden entscheidend vergrößert. Die chirurgische Gaumennahterweiterung führt darüber hinaus zu einer deutlichen Vergrößerung von Nasenvolumen und Nasenklappe mit auch subjektiver Verbesserung der Nasenatmung. Sonographisch waren die Segmentbewegung im Laufe der Dehnung ebenso nachweisbar wie die spätere Reossifizierung und vollständige Rekortikalisierung.Die Messungen belegen einen ausgeprägten Einfluss der chirurgisch unterstützten Gaumennahterweiterung auf die skelettalen Strukturen des Mittelgesichtes, deren deutliche Weitung durch nicht invasive Untersuchungsverfahren nachweisbar ist. Die sonographische Untersuchung kann den Fortschritt der transversalen Dehnung objektivieren und erlaubt eine individuelle Anpassung der Retentionszeit ohne zusätzliche Strahlenexposition.

DIRECT GRAFTING OF RGD-MOTIF-CONTAINING PEPTIDE ON THE SURFACE OF POLYCAPROLACTONE FILMS

Direct surface modification of biodegradable polycaprolactone (PCL) was performed without the necessity of synthesis of functionisable co-polymers. An easy-to-perform three-step procedure consisting of amination, reaction with hetero-bifunctional cross-linkers and conjugation of an RGD-motif-containing peptide was used to modify polymer films and improve the attachment of endothelial cells. The biological activity of modified surfaces was assessed by estimating microvascular endothelial cell attachment. Covalent coating with RGD resulted in an approximately 11-fold increase of endothelial cell attachment on modified PCL surfaces compared with untreated polymer. The specificity of the attachment enhancement was confirmed by using a control peptide. It is concluded that chemical surface modification is an appropriate method of rendering degradable polymers, such as PCL, cell-adhesive.

The influence of cephalometrics on orthodontic treatment planning

Since its introduction, cephalometrics, i.e. cephalometric radiography and analysis, has been used for orthodontic treatment planning. However, the effectiveness of this diagnostic method remains questionable. A randomized crossover study was designed to assess the influence of cephalometrics in orthodontic treatment planning of individual patients. Diagnostic records of 48 subjects (24 males and 24 females aged 11-14 years) were divided in two stratified groups and assigned to one of two combinations: A, dental casts only, and B, dental casts, cephalometric radiographs, and analysis. The records were presented to 10 orthodontic postgraduates and four orthodontists for formulation of orthodontic treatment plans containing a dichotomous decision regarding the use of a functional appliance (FUNC), rapid maxillary expansion (RME), and extraction (EXTR). The combination of FUNC + RME + EXTR was used as the basis of the outcome measure. Agreement on orthodontic treatment planning using all possible comparisons of diagnostic records of individual patients (AB, AA, and BB) was assessed and overall proportions of agreement (OPA) were calculated for orthodontic postgraduates and orthodontists separately. Median OPA were 0.60 (AB), 0.65 (AA), and 0.60 (BB) for orthodontic postgraduates and 0.50 (AB), 0.75 (AA), and 0.50 (BB) for orthodontists. Irrespective of the level of experience, neither consistency of orthodontic treatment planning between both combinations of diagnostic records showed a statistically significant difference (P > 0.05) using Wilcoxon signed rank test nor did consistencies and agreement of orthodontic treatment planning after the addition of cephalometrics. It appears that cephalometrics are not required for orthodontic treatment planning, as they did not influence treatment decisions.

Relationship between patient discomfort, appliance acceptance and compliance in orthodontic therapy.

Abstract: Orthodontic treatment is occasionally a discomfort to patients, due to pain or functional restrictions. In this context, several retrospectively planned studies were performed in the 1980s, but correlations between different aspects of patient discomfort were not investigated. The present study aimed at examining and structuring the psychogenic dimensions of patient discomfort. Furthermore, the impact of the patients attitude on the intensity of discomfort was to be evaluated in addition to the influences of appliance therapy.The study was performed with 67 patients from 9 to 32 years. Prior to insertion of a new appliance, psychogenic scales reflecting their attitude towards orthodontic therapy were submitted to them. They were instructed to keep a discomfort log during the first 7 days after insertion. After 6 months they were given lists for retrospective assessment of discomfort and an appliance-acceptance scale to be filled in. At the same time, the respective orthodontist assessed his patients compliance on a cooperation scale.The factor analysis revealed 3 levels of patient discomfort: feelings of tension, functional restrictions and aversion to wearing an orthodontic appliance in public. Appliance acceptance after 6 months could be predicted from the attitude towards treatment and the experienced discomfort. Patient compliance also correlated with these factors, so that causal flow diagrams of the investigated variables could be produced.Giving detailed information on any discomfort occuring and explaining how to reduce or eliminate it are vital factors in good treatment cooperation.Zusammenfassung: Die kieferorthopädische Behandlung wird vom Patienten wegen auftretender Schmerzen oder funktioneller Einschränkungen bisweilen als unangenehm empfunden. In den 80er Jahren wurden hierzu mehrere, allerdings retrospektiv angelegte Studien durchgeführt. Wechselbeziehungen zwischen verschiedenen Aspekten der Patientenbeschwerden wurden nicht untersucht. Ziel der vorliegenden Untersuchung war es daher, die psychologischen Dimensionen der Patientenbeschwerden herauszuarbeiten und zu strukturieren. Zusätzlich sollte, neben den Einflüssen der Gerätetherapie, die Rolle der Patienteneinstellung auf die Stärke der Beschwerden evaluiert werden.Die Studie wurde mit 67 Patienten im Alter von neun bis 32 Jahren durchgeführt. Vor dem Einsetzen eines neuen Gerätes wurden ihnen psychologische Skalen über die Einstellung zur kieferorthopädischen Therapie vorgelegt. In den ersten sieben Tagen nach dem Einsetzen wurden sie angewiesen, ein Beschwerdentagebuch zu führen. Nach sechs Monaten wurden den Patienten Listen zur retrospektiven Einschätzung der Beschwerden und eine Geräteakzeptanzskala zur Beantwortung überlassen. Der jeweilige kieferorthopädische Behandler schätzte zugleich die Mitarbeit seines Patienten auf einer Kooperationsskala ein.Die Faktorenanalyse ergab drei Ebenen der Patientenbeschwerden: Spannungsgefühle, funktionelle Einschränkungen und die Abneigung, ein kieferorthopädisches Gerät in der Öffentlichkeit zu tragen. Die Geräteakzeptanz nach sechs Monaten konnte anhand der Einstellung vor der Behandlung und der empfundenen Beschwerden vorhergesagt werden. Auch Patientenmitarbeit stand in Beziehung zu diesen Faktoren, sodass kausale Flussdiagramme der untersuchten Variablen erstellt werden konnten.Für eine gute Kooperation bei der Behandlung sind die ausführliche Aufklärung der Patienten über auftretende Beschwerden und das Erläutern von Möglichkeiten, diese zu beseitigen oder zu verringern, von eminenter Bedeutung.

The adaptive response of jaw muscles to varying functional demands

Jaw muscles are versatile entities that are able to adapt their anatomical characteristics, such as size, cross-sectional area, and fibre properties, to altered functional demands. The dynamic nature of muscle fibres allows them to change their phenotype to optimize the required contractile function while minimizing energy use. Changes in these anatomical parameters are associated with changes in neuromuscular activity as the pattern of muscle activation by the central nervous system plays an important role in the modulation of muscle properties. This review summarizes the adaptive response of jaw muscles to various stimuli or perturbations in the orofacial system and addresses general changes in muscles as they adapt, specific adaptive changes in jaw muscles under various physiologic and pathologic conditions, and their adaptive response to non-surgical and surgical therapeutic interventions. Although the jaw muscles are used concertedly in the masticatory system, their adaptive changes are not always uniform and vary with the nature, intensity, and duration of the stimulus. In general, stretch, increases neuromuscular activity, and resistance training result in hypertrophy, elicits increases in mitochondrial content and cross-sectional area of the fibres, and may change the fibre-type composition of the muscle towards a larger percentage of slow-type fibres. In contrast, changes in the opposite direction occur when neuromuscular activity is reduced, the muscle is immobilized in a shortened position, or paralysed. The broad range of stimuli that affect the properties of jaw muscles might help explain the large variability in the anatomical and physiological characteristics found among individuals, muscles, and muscle portions.

Structural changes of acid etched enamel examined under confocal laser scanning microscope

ZusammenfassungZiel der vorliegenden Studie war es, mit konfokaler Laser-Scanning-Mikroskopie (CLSM) Strukturveränderungen in säuregeätztem und unter remineralisierenden Bedingungen behandeltem Schmelz mit einer neuen mikroskopisch-tomographischen Technik sichtbar zu machen. Schmelzblöcke wurden mit 37% Phosphorsäure geätzt und drei Wochen dem Mundmilieu ausgesetzt. Danach wurden mit CLSM mikroskopische Tomogramme der Schmelzstückchen aufgenommen und mit Kontrollproben verglichen. CLSM erwies sich dabei als zuverlässige und einfache Methode, strukturelle Veränderungen in Schmelzbereichen bis etwa 100 Μm Tiefe reproduzierbar sichtbar zu machen. Säurebehandlung führte zu bleibenden Strukturveränderungen bis 100 Μm unter der Oberfläche, die auch nach Verweilen der Probekörper im Mund unter der Oberfläche beobachtet werden konnten. Veränderungen gegenüber unbehandelten Kontrollproben manifestierten sich durch unterschiedliche Lichtreflexion, speziell durch eine hyperreflexible Zone, die sich in Form eines 10 bis 15 Μm breiten Bandes unter der geätzten Oberfläche ausbreitete. Dieser Befund spricht dafür, daß auf und unmittelbar unterhalb der geätzten Schmelzoberfläche im Mundmilieu aus dem Speichel Ablagerungen gebildet werden. Sobald die qualitativen CLSM-Befunde mit quantitativen Ergebnissen korreliert werden, kann der Einsatz dieser Methode größere Remineralisationsstudien erheblich erleichtern.SummaryThe aim of the present investigation was to elucidate structural alterations in enamel subjected to acid etch technique and treatment under remineralizing conditions by means of a new microscopy technique known as confocal laser scanning microscopy (CLSM). Blocks of enamel were treated with 37% phosphoric acid and exposed for 3 weeks to an oral environment. Tomographic CLSM images were subsequently obtained and compared with controls. CLSM proved to be a reliable, highly reproducible and simple method of qualitative assessment of structural changes occurring on the surface of enamel and in areas below the surface as deep as 100 Μm or more. Structural alterations associated with acid application were observed to occur up to 100 Μm below the surface; these largely remained after exposure to an oral environment. Changes manifested as differential light reflection were detected in experimental samples in the form of a hyperreflexible zone extending as a 10 to 15 Μm wide band below the etched surface. This finding indicates that deposition of salivary material occurs on and below the surface of etched enamel exposed to an oral environment. Once qualitative results of CLSM are correlated with quantitative measurements, this technique may facilitate large scale remineralization studies.The aim of the present investigation was to elucidate structural alternations in enamel subjected to acid etch technique and treatment under remineralizing conditions by means of a new microscopy technique known as confocal laser scanning microscopy (CLSM). Blocks of enamel were treated with 37% phosphoric acid and exposed for 3 weeks to an oral environment. Tomographic CLSM images were subsequently obtained and compared with controls. CLSM proved to be a reliable, highly reproducible and simple method of qualitative assessment of structural changes occurring on the surface of enamel and in areas below the surface as deep as 100 microns or more. Structural alterations associated with acid application were observed to occur up to 100 microns below the surface; these largely remained after exposure to an oral environment. Changes manifested as differential light reflection were detected in experimental samples in the form of a hyper-reflexible zone extending as a 10 to 15 microns wide band below the etched surface. This finding indicates that deposition of salivary material occurs on and below the surface of etched enamel exposed to an oral environment. Once qualitative results of CLSM are correlated with quantitative measurements, this technique may facilitate large scale remineralization studies.

Perception of occlusion, psychological impact of dental esthetics, history of orthodontic treatment and their relation to oral health in naval recruits

OBJECTIVE To investigate whether the oral health of young male adults was related to (1) the degree of self-perceived malocclusion, (2) the degree of experienced negative psychosocial impact of dental esthetics, and (3) the history of orthodontic treatment and its duration. MATERIALS AND METHODS The study subjects were 470 male naval recruits undergoing a routine dental health checkup. They answered the Perception of Occlusion Scale (POS) and Negative Impact of Dental Aesthetics Scale (NIDAS). The Approximal Plaque Index (API), the Sulcus Bleeding Index (SBI), and the number of decayed teeth (DT) and missing teeth (MT) were examined by a staff dentist. Statistical procedures were one-way analyses of variance in the API and SBI and nonparametric Kruskal-Wallis, Mann-Whitney, and chi(2) tests in DT and MT as dependent variables. RESULTS (1) The subjects ranging within the upper POS quartile scored higher on the SBI (contrast: P = .003) and DT (P = .002) than did those in the lower POS quartiles. (2) In contrast to the subjects reporting minor negative impacts in the NIDAS, those with strong impacts had higher scores on the API and MT (each P < .001). (3) In the subjects with a history of orthodontic treatment lasting 30 months and longer, lower API (P < .05), SBI and DT (each P = .002), and MT (P = .007) scores were found than in the subjects without previous orthodontic treatment. CONCLUSION The results suggest that self-perceived dental irregularity and negative impact of dental esthetics might affect oral health, whereas previous extensive orthodontic treatment may have favorable effects by improving dental health compliance.

An experimental study of the esthetic effect of facial profiles

In this study good-looking “male” and “female” as well as ugly facial profiles were shaped by 104 lay persons using an especially constructed device according to specific instructions. These profiles were photographed and subsequently evaluated using a series of parameters from soft tissue profile analyses. Although some significant mean value differences were found between the good-looking and ugly profile variants, they were not substantial. In contrast, markedly significant differences were revealed between the variances of all variables. In some instances the variance of the ugly profiles was more than 3 to 4 times higher than that of the good-looking profiles. These findings were convicingly confirmed when statistical distribution of the data was established and compared. This implies that perception of beauty is associated with regularity of facial features and is conveyed by measurement values which are located close to the mean. Ugliness is associated with extreme deviations from the latter in either direction. Apart from the facial proportions, the degree of convexity or concavity of facial profile and their sequence seem to be important for the esthetic effects. “Male” profiles in contrast to “female” profiles exhibited more conspicuous facial features such as pronounced convexity and concavity.ZusammenfassungIn der vorliegenden Studie wurden von 104 Laien mit einem zu diesem Zweck konstruierten Profildarstellungsgerät nach festgelegten Anweisungen Profile gestaltet, und zwar ein schönes “männliches”, ein schönes “weibliches” und ein häßliches Gesichtsprofil. Die Darstellungen wurden fotografiert und mit einer Reihe von Parametern aus Weichteilprofilanalysen ausgewertet. Zwischen den schönen Profilvarianten und den häßlichen Profilen gab es zwar einige signifikante Mittelwertsunterschiede, diese waren jedoch nicht sehr groß. Dagegen zeigten sich große signifikante Unterschiede in den Varianzen aller Variablen. Die Varianz der häßlichen Profile war zum Teil mehr als drei- bis vierfach so groß wie die Varianz der schönen Profile. Der Vergleich der Verteilungen zeigt diesen Sachverhalt ebenfalls in eindrucksvoller Weise. Das bedeutet, daß Schönheit im Sinne von Regelmäßigkeit durch Merkmalsausprägungen zum Ausdruck gebracht wird, die sich eng um einen Zentralwert scharen. Häßlichkeit wird in Abweichung davon durch Extremausprägungen in beide Richtungen dargestellt. Neben den Gesichtsproportionen scheinen die Ausprägungen der Konvexitäten und Konkavitäten des Gesichtsprofils und deren Abfolge eine Bedeutung für die ästhetische Wirkung zu haben. “Männliche” Profile unterschieden sich von “weiblichen” durch markantere Gesichtszüge (stärkere Konvexität und Konkavität).

Determination of the relationship between collagen cross-links and the bone–tissue stiffness in the porcine mandibular condyle

Although bone-tissue stiffness is closely related to the degree to which bone has been mineralized, other determinants are yet to be identified. We, therefore, examined the extent to which the mineralization degree, collagen, and its cross-links are related to bone-tissue stiffness. A total of 50 cancellous and cortical bone samples were derived from the right mandibular condyles of five young and five adult female pigs. The degree of mineralization of bone (DMB) was assessed using micro-computed tomography. Using high-performance liquid chromatography, we quantified the collagen content and the number of cross-links per collagen molecule of two enzymatic cross-links: hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP), and one non-enzymatic cross-link: pentosidine (Pen). Nanoindentation was used to assess bone-tissue stiffness in three directions, and multiple linear regressions were used to calculate the correlation between collagen properties and bone-tissue stiffness, with the DMB as first predictor. Whereas the bone-tissue stiffness of cancellous bone did not differ between the three directions of nanoindentation, or between the two age groups, cortical bone-tissue stiffness was higher in the adult tissue. After correction for DMB, the cross-links studied did not increase the explained variance. In the young group, however, LP significantly improved the explained variance in bone-tissue stiffness. Approximately half of the variation in bone-tissue stiffness in cancellous and cortical bone was explained by the DMB and the LP cross-links and thus they cannot be considered the sole determinants of the bone-tissue stiffness.

The masticatory system under varying functional load. Part 2: effect of reduced masticatory load on the degree and distribution of mineralization in the rabbit mandible

A reduction in mechanical loading of the mandible brought about by mastication of soft food is assumed to decrease the remodelling rate of bone, which, in turn, might increase the degree of bone mineralization. The effect of a reduction in masticatory functional load on the degree and distribution of mineralization of mandibular bone was investigated in male juvenile New Zealand White rabbits. The experimental animals (n=8) had been raised on a diet of soft pellets from 8 to 20 weeks of age, while the controls (n=8) had been fed pellets of normal hardness. The degree of mineralization of bone (DMB) was assessed at the attachment sites of various jaw muscles, the condylar head, and the alveolar process. Differences between groups and among sites were tested for statistical significance using a Students t-test and one-way analysis of variance, respectively. The DMB did not differ significantly between the experimental and control animals at any of the sites assessed. However, in the rabbits that had been fed soft pellets, both cortical bone at the attachment sites of the temporalis and digastric muscles and cortical bone in the alveolar process had a significantly higher DMB than cortical bone at the attachment site of the masseter muscle, while there were no significant differences among these sites in the control animals. The results suggest that a moderate reduction in masticatory functional load does not significantly affect the remodelling rate and the DMB in areas of the mandible that are loaded during mastication but might induce a more heterogeneous mineral distribution.