Winfried Harzer

Profile and competences for the graduating European dentist – update 2009

This paper presents the profile and competences for the European Dentist as approved by the General Assembly of the Association for Dental Education in Europe at its annual meeting held in Helsinki in August 2009. A new taskforce was convened to update the previous document published in 2005. The updated document was then sent to all European Dental Schools, ministries of health, national dental associations and dental specialty associations or societies in Europe. The feedback received was used to improve the document. European dental schools are expected to adhere to the profile and the 17 major competences but the supporting competences may vary in detail between schools. The document will be reviewed once again in 5 years time. Feedback to the newly published document is welcomed and all dental educators are encouraged to draw upon the content of the paper to assist them in harmonising the curriculum throughout Europe with the aim of improving the quality of the dental curriculum.

Sensitivity of Titanium Brackets to the Corrosive Influence of Fluoride-Containing Toothpaste and Tea

Titanium brackets are used in orthodontic patients with an allergy to nickel and other specific substances. In recent studies, the corrosive properties of fluoride-containing toothpastes with different pH values were investigated. The present in vivo study tested how the surfaces of titanium brackets react to the corrosive influence of acidic fluoride-containing toothpaste during orthodontic treatment. Molar bands were placed on 18 orthodontic patients. In these same patients, titanium brackets were bonded on the left quadrants and stainless steel brackets on the right quadrants of the upper and lower arches. Fifteen patients used Gel Kam containing soluble tin fluoride (pH 3.2), whereas 3 used fluoride-free toothpaste. The brackets were removed for evaluation by light microscopy and scanning microscopy 5.5 to 7.0 months and 7.5 to 17 months after bonding. The quality and quantity of elements present were measured by scanning microscopy. Macroscopic evaluation showed the matte gray color of titanium brackets dominating over the silver gleam of the steel brackets. The plaque accumulation on titanium brackets is high because of the very rough surface. Pitting and crevices were observed in only 3 of the 165 brackets tested. The present in vivo investigation confirms the results of in vitro studies, but the changes are so minor that titanium brackets can safely be used for up to 18 months. Wing surfaces should be improved by modifying the manufacturing process.

Rapid maxillary expansion with palatal anchorage of the hyrax expansion screw--pilot study with case presentation.

Abstract.Background:Rapid maxillary expansion (RME) with the appliance fixed at the crowns of the first premolars and molars leads not only to transversal expansion but also to tipping of the anchorage teeth and a risk of increased tooth mobility as well as of root and bone resorptions. These disadvantages were to be avoided by fixing the transversal screw directly to the hard palate.Material and Method:Following preliminary experimental work to determine the extent to which the hard palate could be loaded with orthodontic implants, two female patients were treated for extreme transverse maxillary deficiency using a Hyrax expansion screw fixed on one side with an implant with the following dimensions: length 4.0 mm, diameter 3.5 mm, abutment diameter 5.00 mm (EO implant, Straumann, Freiburg i. Br., Germany), and on the other side with a bone screw between the roots of the second premolars and the first molars. Presurgical osteotomy according to Glassmann was followed immediately by loading, i. e. by expansion through activation of the screw several times per day. Additional anterior guidance of the right and left maxilla was provided by crossed segmented archwires and a tension coil spring for space opening in the incisor region. After adequate expansion by 8.0 mm and correction of the position of the buccal teeth, the Hyrax expansion screw and the osteosynthesis screw were removed. The implant served as orthodontic anchorage for a molar-to-molar transpalatal bar aimed at preventing relapse.Results and Conclusions:The tooth axis inclination measured on cut sections of the plaster casts made at the beginning and end of treatment was largely without transversal discrepancies. Direct fixing of the transversal screw in the palatal arch prevents buccal tipping of the posterior teeth, especially in patients with a small apical base. Compared with other direct procedures involving osteosynthesis plates, this technique offers adequate guiding stability and is minimally invasive.Zusammenfassung.Hintergrund:Die forcierte Gaumennahterweiterung mit Fixierung der Apparatur an den Kronen der ersten Prämolaren und Molaren führt neben der transversalen Expansion zur Kippung der Verankerungszähne. Außerdem besteht das Risiko der Zahnlockerung, der Wurzel- und Knochenresorption. Mit der direkten Fixierung der Transversalschraube am knöchernen Gaumen sollen diese Nachteile vermieden werden.Material und Methode:Nach experimenteller Vorarbeit hinsichtlich der Belastungsfähigkeit des knöchernen Gaumens durch orthodontische Implantate wurde bei zwei Patientinnen zur Korrektur eines extremen Schmalkiefers die Hyraxschraube einerseits mit einem Implantat mit 4,0 mm Länge, 3,5 mm Durchmesser und Auflage (5,0 mm) (EO-Implantat, Straumann, Freiburg i. Br., Deutschland) und andererseits mit einer Knochenschraube zwischen den Wurzeln der zweiten Prämolaren und ersten Molaren befestigt. Nach kortikaler Knochenschwächung (Methode nach Glassmann) erfolgte eine sofortige Belastung bzw. Dehnung durch mehrmalige Aktivierung der Schraube pro Tag. Mittels überkreuzter Teilbögen und einer Zugfeder zur Lückenöffnung im Schneidezahnbereich erfolgte eine zusätzliche anteriore Führung der beiden Kiefersegmente. Nach ausreichender Weitung von 8,0 mm und Überstellung der Seitenzähne wurden die Hyraxschraube und die Knochenschraube entfernt. Das Implantat diente als orthodontische Verankerung für einen Transpalatinalbogen, der von den Molaren ausging und zur Retention der erzielten Weitung diente.Ergebnisse und Schlussfolgerungen:Die an Sägeschnitten der Anfangs- und Endmodelle gemessene Zahnachsenneigung blieb weitestgehend parallel. Mit der direkten Fixierung der Transversalschraube im Gaumenbogen kann vor allem bei kleiner apikaler Basis eine Bukkalkippung der Seitenzähne vermieden werden. Gegenüber anderen direkten Verfahren, mit breiter Anlagerung der Osteosyntheseplatten, ist das Verfahren bei ausreichender Führungsstabilität minimal invasiv.

Skeletally-anchored Rapid Maxillary Expansion using the Dresden Distractor

Introduction:It was the aim of this study to carry out a 3-D analysis of the teeth, alveolar and skeletal structures during bone-borne, surgically-assisted rapid maxillary expansion (RME) with the Dresden Distractor (DD). We aimed to determine whether a translatory and skeletal movement of the segments would be possible while reducing the dento-alveolar side effects associated with tooth-borne RME.Materials and Methods:Standardized axial computed tomography (CT) was performed on twelve patients averaging 25.3 years of age prior to and after RME with the DD. Reference planes and the triple-0-ELSA were defined bilaterally referring to the following anatomic points: the foramina spinosa, external auditory meati and the anterior margin of the foramen magnum. We measured the amount of movement that occurred before and after RME with the DD against ELSA.Results:A screw activation of 6.0 mm led to a transverse expansion of 5.55 mm in the alveolar process in the premolar region, and of 4.87 mm in the molar region, with 8° to 9.8° of buccal tipping and an increase in width of 6.07 mm and 5.71 mm, respectively, occurred in conjunction with only slight buccal tipping of the premolars (3.1°–4.6°) and molars (1,1°–2.6°). These data signify, beyond the considerable skeletal efficacy, an uprighting of the teeth due to the multibracket appliances torque effect, and a direct transfer of the expansion forces onto the bone. Autorotation of the mandible in forward and upward directions was possible due to the considerably less dental tipping resulting from RME with the DD in comparison to tooth-borne RME. This fact demonstrated that the DD is also well-suited for patients with vertical growth pattern.Conclusion:The bone-borne DD is an effective therapeutic method that spares the patient the negative side effects associated with tooth-borne RME such as root resorption, bone dehis- cence, bite opening and excessive buccal tipping of the teeth. The prerequisites for stable occlusion are brought about by the fact that the expansion is skeletal in nature, with minimal dental tipping.ZusammenfassungZiel:Ziel der Studie war die 3-D-Analyse von Zähnen, alveolären und skelettalen Strukturen bei der knochenverankerten, chirurgisch unterstützten Gaumennahterweiterung (GNE) mit dem Dresden Distraktor (DD). Es sollte überprüft werden, ob eine körperliche und skelettale Bewegung der Segmente mit einer Reduktion der bei der zahngetragenen Gaumennahterweiterung auftretenden dentoalveolären Nebenwirkungen erreicht werden kann.Material und Methodik:Bei zwölf Patienten, Durchschnittsalter 25,3 Jahre, wurden vor und 6,8 Monate nach der GNE mit dem DD standardisierte axiale Computertomogramme (CTs) erstellt. Mittels der anatomischen Referenzpunkte Foramina spinosa und Pori acustici externi beidseits sowie dem Vorderrand des Foramen magnum wurden Referenzebenen und der Tripel-Nullpunkt ELSA definiert. Bewegungen der Messpunkte vor und nach GNE wurden gegen ELSA vermessen.Ergebnisse:Die Schraubenerweiterung von 6,00 mm führte am Alveolarfortsatz in der Prämolarenregion zu 5,55 mm und in der Molarenregion zu 4,87 mm transversaler Erweiterung mit 8°–9,8° Bukkalkippung. Die geringere Bukkalkippung der Prämolaren von 3,1°–4,6° und der Molaren von 1,1°–2,6° bei einer Breitenzunahme von 6,07 mm bzw. 5,71 mm verdeutlichte neben der großen skelettalen Effektivität eine Aufrichtung der Zähne durch den Torqueeffekt der Multibracketapparatur und die direkte Einleitung der Expansionskräfte auf den Knochen. Die im Gegensatz zur zahngetragenen GNE geringe Zahnkippung der GNE mit dem DD erlaubte eine Autorotation der Mandibula nach ventral und kranial, so dass der DD auch bei vertikalem Wachstum gut geeignet war.Schlussfolgerung:Der knochenverankerte DD ist eine effektive Therapiemethode, welche vor unerwünschten Nebenwirkungen zahngetragener GNE wie Wurzelresorptionen, Knochendehiszenzen, Bissöffnung und exzessiver Bukkalkippung der Zähne schützt. Die vorwiegend skelettale Expansion bei geringer Zahnkippung schafft die Voraussetzung für eine stabile Okklusion.

Orthodontic Space Opening in Patients with Congenitally Missing Lateral Incisors

OBJECTIVE To determine the best time to begin orthodontic treatment for patients scheduled for implants to replace congenitally missing upper lateral incisors. The aim of timing is to maximize the amount of bone available for implant insertion and to improve incisors inclination. MATERIALS AND METHODS Seventy-three plaster casts of 14 patients with 26 missing lateral incisors were cross sectioned in the center of the planned insertion of the implant, and the implant profile was projected into the area at three different times: T1--beginning of orthodontic treatment, T2-- end of orthodontic treatment, and T3--implant insertion. Deficiency of alveolar ridge volume needed for implantation was determined by Leica Quin analySIS software. RESULTS An increase of ridge-volume deficiency from 0.26 mm(2) at T1 to 3.77 mm(2) at T3 was found. During orthodontic treatment the incisors protruded about 9.4 degrees (differing from the O1-NA standard of 7.5 degrees ). To ensure optimal esthetic and functional implantation results, time management concerning orthodontic treatment has to be done carefully. CONCLUSIONS To avoid a high degree of alveolar bone atrophy and the risk of relapse and retreatment, orthodontic treatment involving tooth movement should not be initiated before the age of 13 years. Furthermore, it is important to maintain anchorage of the upper incisors because high incisor proclination causes extra-axial stress on the implant. An interdisciplinary approach is essential to provide the best treatment outcome.

Differential expression of myosin heavy-chain mRNA in muscles of mastication during functional advancement of the mandible in pigs

Surgical and orthodontic treatment of retrognathia aims to improve orofacial function by adaptation and training of muscle capacity, which is connected with a change in muscle fibre-type proportions. The aim here was to analyse the proportion of myosin-heavy chain (MyHC) gene expression in type I (slow twitch/ST) and type IIb (fast twitch/FT) fibres during sagittal advancement of the mandible by reverse transcriptase-polymerase chain reaction (RT-PCR). The experiments were carried out on 10-week-old pigs (six test animals, six controls) over a 28-day period. Six pigs were fitted with acrylic bite blocks for sagittal advancement of the mandible. Tissue was taken from seven different regions of the masseter, temporal, medial pterygoid, and geniohyoid muscles. The 84 samples were used for histological fibre differentiation with ATPase staining and for isolation of total RNA. To measure the two MyHC isoforms, RT-PCR (in a single tube reaction with MyHC I, MyHC IIb, and GAPDH primers) was used. A significant increase was registered in the percentage of ST fibres and in mRNA from MyHC I in the anterior region of the masseter and in the posterior region of the temporal muscle of the treated animals. The proportion of ST fibres to FT fibres was increased by up to 12% after functional advancement of the mandible. The histological findings corresponded with the data for fibre mRNA generated by RT-PCR.

Die kieferorthopädische Einordnung retinierter Eckzähne unter besonderer Berücksichtigung des Behandlungsalters, der Angulation und der dynamischen Okklusion

ZusammenfassungDie chirurgisch-kieferorthopädische Einordnung wird von den meisten Autoren als optimale Therapievariante bei Eckzahnretention angesehen. Trotzdem kommt es häufig zu langen Behandlungszeiten und funktionellen Dysharmonien nach Abschluß der Behandlung. Dies war Anlß zu einer Erfolgsbewertung des Verfahrens unter besonderer Berücksichtigung des Behandlungsalters, der Angulation und der dynamischen Okklusion. Die Nachuntersuchungen bis zu fünf Jahren nach Behandlungsschluß bei 66 Patienten ergaben primär eine Korrelation zwischen Behandlungserfolg und dem Alter zu Beginn der Behandlung. Des weiteren konnten Patienten mit Deckbiß und Zahnzahlanomalien als Risikogruppe identifiziert werden. Als Okklusionstyp herrscht die Gruppenführung vor. Bei einem Behandlungsbeginn vor dem dritten Dezennium gehen die maximalen Behandlungszeiten nicht über 3,5 Jahre hinaus.SummaryThe literature regards the surgical-orthodontic treatment of ectopic canine as being the optimal therapy. This treatment, however, often takes a long time and disturbances in the functional occlusion often occur after treatment is ended. For this reason it was decided to evaluate the treatments success taking into consideration age at time of treatment, angulation, and functional occlusion. The post-treatment examinations of 66 patients up to five years after treatment reveal above all a correlation between treatment success and age at the time treatment begins. In addition patients with class II/2 and tooth aplasia were identified as constituting a risk group. These malocclusions therefore, are a sign that there is a risk of ectopic canines. The occlusion type in laterotrusion movement provides group guidance. Beginning treatment after age 25 years should be critically evaluated, because the treatment period is prolonged.The literature regards the surgical-orthodontic treatment of ectopic canine as being the optimal therapy. This treatment, however, often takes a long time and disturbances in the functional occlusion often occur after treatment is ended. For this reason it was decided to evaluate the treatments success taking into consideration age at time of treatment, angulation, and functional occlusion. The post-treatment examinations of 66 patients up to five years after treatment reveal above all a correlation between treatment success and age at the time treatment begins. In addition patients with class II/2 and tooth aplasia were identified as constituting a risk group. These malocclusions, therefore, are a sign that there is a risk of ectopic canines. The occlusion type in laterotrusion movement provides group guidance. Beginning treatment after age 25 years should be critically evaluated, because the treatment period is prolonged.

Comparative study of excitation patterns in the masseter muscle before and after orthognathic surgery

This study was designed to inquire into changes occurring in the electromyographic activity throughout the masseter muscle after orthognathic surgical treatment of various bite anomalies. A total of 32 adult patients showing distinct class II (n = 15) or class III malocclusions (n = 17) were entered into the investigation. All patients had monopolar surface electromyograms of the masseter muscle taken prior to presurgical orthodontic treatment and after removal of their orthodontic appliances after surgery. Twenty eugnathic adult patients served as controls. Unlike bipolar lead readings, simultaneous sampling from 16 electrodes permits the registration of the overall excitation pattern in the entire muscle. Recordings were taken during clenching, chewing and protrusion of the lower jaw against a defined force. Comparison with preoperative EMGs proved postsurgical distribution of excitation in class 11 patients to approximate the excitation pattern of eugnathic patients. By contrast, correction in class III malocclusions produced a shift in excitation maxima in the sense of a cranial advance. Harmonization, as evident in class II patients, did not occur. The postoperative discords in masseter excitation patterns, as observed after correction of class III anomalies, are indicative of the risk of relapse and the prolonged phase of retention associated with these conditions.

Changes in nasal volume after surgically assisted bone-borne rapid maxillary expansion

INTRODUCTION The purposes of this study were to detect, locate, and examine the changes in transverse nasal width, area, and volume from bone-borne, surgically assisted rapid maxillary expansion (SARME) with the Dresden distractor by using computer tomography (CT). METHODS Sixteen patients (average age, 28.7 years) underwent axial CT scanning before and 6 months after SARME. They also underwent CT fusion on specific bony structures. The nasal bone width was examined in the coronal plane. The cross-sectional images of the nasal cavity were taken of the area surrounding the apertura piriformis, the choanae, and in between. We calculated cross-sectional areas and nasal volume according to these data. RESULTS All but 2 patients had an increase in nasal volume of at least 5.1% (SD, 4.6%). The largest value of 35.3% (SD, 45.8%) was measured anteriorly on the nasal floor, decreasing cranially and posteriorly. This correlated with the V-shaped opening of the sutura palatina. There was no significant correlation between increase in nasal volume and transversal expansion. CONCLUSIONS Because most of the air we breathe passes over the lower nasal floor, SARME is likely to improve nasal breathing.

CT Analysis of Nasal Volume Changes after Surgically-assisted Rapid Maxillary Expansion

Objective:Aim of this study was to detect the changes in nasal volume due to bone-borne, surgically-assisted rapid palatal expansion (RPE) with the Dresden Distractor using computed tomography (CT).Materials and Methods:17 patients (mean age 28.8) underwent axial CT scanning before and 6 months after RPE. The nasal bone width was examined in the coronal plane. Cross-sectional images of the nasal cavity were taken of the area surrounding the piriform aperture, choanae and in between. Bony nasal volume was computed by connecting the three cross-sectional areas.Results:All but two patients showed a 4.8% increase in nasal volume (SD 4.6%). The highest value, 33.3% (SD 45.1%), was measured anteriorly at the level of the nasal floor. This correlated with the midpalatal suture’s V-shaped opening. There was no significant correlation between an increase in nasal volume and transverse dental arch expansion.Conclusion:As most of the air we breathe passes the lower nasal floor, an improvement in nasal breathing is likely.ZusammenfassungZiel:Ziel der Studie war die Messung der Vergrößerung des Nasenvolumens nach chirurgisch unterstützter, implantatgestützter forcierter Gaumennahterweiterung (RPE) mit dem Dresden Distraktor (DD) unter Verwendung der Computertomographie (CT).Material und Methodik:17 Patienten mit einem Durchschnittsalter von 28,8 Jahren wurden in die Auswertung der prächirurgischen und postoperativen (6 Monate) CT-Aufnahmen nach RPE einbezogen. Die transversale Expansion wurde in der Koronalebene vermessen. Die Querschnitte wurden auf der Höhe der Apertura piriformis, der Choanen und mittig dazu kalkuliert. Das Volumen wurde durch Verbindung der drei Querschnittsflächen berechnet.Ergebnisse:Alle Patienten mit Ausnahme von zwei zeigten eine Zunahme des Nasenvolumens um durchschnittlich 4,8% (SD 4,6%). Der größte Wert von 33,3% (SD 45,1%) wurde anterior am Nasenboden gemessen. Dies entspricht einer V-förmigen Öffnung der Sutura palatina mediana. Es bestand keine Korrelation zwischen der Zunahme des Nasenvolumens und der transversalen Expansion im Zahnbogen.Schlussfolgerung:Da die größte Menge der Atemluft den Nasenboden passiert und dort die größte Erweiterung zu verzeichnen war, ist mit einer allgemeinen Verbesserung der Nasenatmung bei den meisten Patienten zu rechnen.