Paul-Georg Jost-Brinkmann

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.

Periodontal disease in patients with ankylosing spondylitis

Objective: Ankylosing spondylitis (AS) and periodontal disease (PD) are characterised by dysregulation of the host inflammatory response, resulting in soft and hard connective tissue destruction. AS has been related to other inflammatory diseases, however, there is a paucity of data on whether AS is associated with inflammatory PD. Methods: The association between AS and PD was examined in 48 patients with AS and 48 healthy controls, matched for age and gender. AS was diagnosed according to the modified New York criteria. Periodontal examination included probing pocket depth (PPD), clinical attachment loss (CAL), plaque index (PI) and bleeding on probing (BOP). Potential risk factors of PD such as smoking, low education, alcohol consumption, body mass index (BMI), as well as chronic diseases associated with PD and AS were assessed through questionnaires. Results: In stepwise logistic regression, including AS status, age, gender, education, smoking, alcohol consumption and BMI, only AS status, age and education remained significant predictors of PD. Patients with AS had significant 6.81-fold increased odds (95% CI 1.96 to 23.67) of PD (defined as mean attachment loss >3 mm) compared to controls. The strength of the association was attenuated but remained statistically significant after further adjustment for plaque accumulation (odds ratio (OR) 5.48, 95% CI 1.37 to 22.00). Conclusions: The present study shows that patients with AS have a significantly higher risk of PD, strongly suggesting the need for close collaboration between rheumatologists, periodontists and dental hygienists when treating patients with AS.

Histologic investigation of the human pulp after thermodebonding of metal and ceramic brackets.

Twenty-five human permanent teeth scheduled for extraction for orthodontic reasons were used to study the effect of thermodebonding on the pulp tissue. One week before brackets were removed the teeth were bonded with either metal or ceramic brackets, with two alternative adhesives. For debonding, three different techniques were used: (1) debonding of ceramic brackets warmed up indirectly by resistance heating of a metallic bow applied to the bracket slot, (2) debonding of metal brackets warmed up directly by inductive heating of the bracket itself, and (3) debonding of ceramic brackets warmed up indirectly by inductive heating of metallic plier tips, applied to the mesial and distal bracket surfaces. Teeth with metal brackets removed without heat by squeezing the wings together served as a control group. The teeth were extracted 24 hours after debonding and subjected to a light microscopic study after histologic preparation and staining. In addition, the location of adhesive remnants was evaluated. While the thermodebonding of metal brackets worked properly and without any obvious pulp damage, there were problems related to the thermodebonding of ceramic brackets: (1) if more than one heating cycle was necessary, several teeth showed localized damage of the pulp with slight infiltration of inflammatory cells, (2) bracket fractures occurred frequently, and enamel damage could be shown, and (3) often with Transbond (Unitek/3M, Monrovia, Calif.) as the adhesive, more than one heating cycle was necessary for bracket removal, and thus patients complained about pain.

Effect of Light-tip Distance on the Shear Bond Strengths of Composite Resin

The purpose of this study was to assess the effect of light-tip distance on the shear bond strength and failure site of brackets cured with three different light curing units: a high-intensity halogen (Astralis 10, 10-second curing), a light-emitting diode (LED, e-Light, six-second curing), and a plasma arc (PAC System, four-second curing). One hundred and thirty-five bovine permanent mandibular incisors were randomly allocated to nine groups of 15 specimens each. Stainless steel brackets were bonded with a composite resin to the teeth, and each curing light was tested at zero, three, and six mm from the bracket. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. When the three light curing units were compared at a light-tip distance of zero mm, the three lights showed no significantly different shear bond strengths. At light-tip distances of three and six mm, no significant differences were found between the halogen and plasma arc lights, but both lights showed significantly higher shear bond strengths than the LED light. When evaluating the effect of the light-tip distance on each light curing unit, the halogen light showed no significant differences between the three distances. However, the LED light produced significantly lower shear bond strengths at a greater light-tip distance, and the plasma arc lamp showed significantly higher shear bond strengths at a greater light-tip distance. In hard-to-reach areas, the use of PAC system is suggested, whereas the LED evaluated in this study is not recommended.

The influence of air polishers on tooth enamel

SummaryThis 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 μm to 7.2 μm 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 μm/min of dentin compared to 339,6 μm/min by the Prophy-Jet® 30.ZusammenfassungDie vorliegende Arbeit vergleicht die Wirkungen vier verschiedener Pulver-Wasser-Strahlgeräte (PWS) (Air-Flow®-S1, Clean-Jet®, Prophy-Jet® 30, Prophy-Unit®) auf Zahnschmelz. Frisch extrahierte Rinderzähne wurden partiell in Kunststoff eingebettet, die Labialflächen plan geschliffen sowie hochglanzpoliert. Anschließend wurden die Zähne mit einem Pulver-Wasser-Strahlgerät für 60 s bestrahlt oder ebensolange mit einer Prophylaxepaste (CCS® 170, CCS® 250 oder Cleanic®) poliert. Die Wirkung der Pulver-Wasser-Strahlgeräte wurde bei einer Vielzahl unterschiedlicher Pulver/Luft- und Wasser-Einstellungen geprüft. Zusätzlich wurde die Wirkung von Pulver-Wasser-Strahlgeräten und Prophylaxepasten auf einige Dentinflächen gemessen. Die bearbeiteten Zahnoberflächen wurden laseroptisch profilometrisch untersucht. Dabei wurde neben mehreren Rauheitskenngrößen auch der Materialabtrag bestimmt. Das Clean-Jet®-Gerät führte bei allen Einstellungen zu signifikant rauheren Oberflächen als die drei Prophylaxepasten. Bei allen untersuchten Einstellungen erzeugten Air-Flow®-S1, Prophy-Jet® 30 und Prophy-Unit® Schmelzrauhigkeiten, die entweder geringer waren als nach Prophylaxepaste-Anwendung oder sich von deren Ergebnis nicht unterschieden. Die drei Polierpasten trugen binnen 60 s 3,6 μm bis 7,2 μm Schmelz ab. Das Clean-Jet®-Gerät trug in allen Einstellungen pro Zeiteinheit signifikant mehr Schmelz ab als die Prophylaxepasten (bis zu 0,1 mm/min), so daß von einer routinemäßigen Anwendung dieses Gerätes abzuraten ist. Der Schmelzverlust durch Air-Flow®-S1, Prophy-Jet® 30 und Prophy-Unit® war entweder geringer als mit den Prophylaxepasten gemessen oder unterschied sich von deren Ergebnis nicht. Das Air-Flow®-S1-Gerät war bei maximaler Wasser-Einstellung jedoch abrasiver als die Cleanic®-Paste. Auf Dentin trug das Air-Flow®-S1-Gerät in einer Minute 641,2 μm ab und das Prophy-Jet® 30-Gerät 339,6 μm.

Microbiologic changes in subgingival plaque before and during the early period of orthodontic treatment

OBJECTIVE To evaluate changes in subgingival microbiota before and during the leveling and alignment orthodontic stage using the polymerase chain reaction (PCR) method. MATERIALS AND METHODS Thirty orthodontic patients (17 females and 13 males; aged 16.7 ± 6.5 y) were included in this study. Subgingival microbial samples were taken from the disto-buccal gingival crevice of the left upper central incisors, the left lower central incisors, the mesio-buccal gingival crevice of the left upper first molars, and the left lower first molars, at four different times: at baseline, before placement of orthodontic appliances (T1), and 1 week (T2), 3 months (T3), and 6 months after placement of orthodontic appliances (T4). DNA was extracted from the samples, and the 16S rRNA-based PCR detection method was used to determine the prevalence of Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Campylobactor rectus, Eikenella corrodens, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola, which are considered as putative periodontopathogens. RESULTS The frequency of T forsythia, C rectus, and P nigrescens significantly increased after placement of orthodontic appliances. For the other species, the frequency tended to increase but no statistically significant difference was noted. The frequency of the change, representing microorganisms not existing at T1 but newly developing at T2, T3, and T4, was higher at the molars than at the incisors. CONCLUSION The placement of orthodontic appliances affects the subgingival microbial composition even during the early period of orthodontic treatment, increasing the prevalence of periodontopathogens, especially in the molar region.

Maxillary protraction with miniplates providing skeletal anchorage in a growing Class III patient

Maxillary protraction headgear has been used in the treatment of Class III malocclusion with maxillary deficiency. However, loss of dental anchorage has been reported with tooth-borne anchorage such as lingual arches and expansion devices. This side effect can be minimized with skeletal anchorage devices such as implants, onplants, mini-implants, and miniplates. The use of miniplates for maxillary protraction in the mixed dentition has not been reported in the literature. This case report describes the treatment of an 8-year-old girl with a Class III malocclusion and maxillary deficiency. Miniplates were used as skeletal anchorage for maxillary protraction followed by phase 2 orthodontic treatment with fixed appliances. Skeletal, dental, and facial changes in response to orthopedic and orthodontic treatment are reported to illustrate the esthetics, function, and stability of treatment with this new technique.

Einfluß der physiologischen Zahnbeweglichkeit auf die Friktion zwischen Bracket und Bogen

ZusammenfassungEs wird eine Apparatur zur Friktionsmessung zwischen Bracket und Bogen vorgestellt, die Messungen in vitro und in vivo erlaubt. Durch den Vergleich der Friktionskräfte, die entstehen, wenn die Brackets auf menschliche Oberkiefer-Inzisivi oder einen unbeweglichen Kunststoffkörper geklebt sind, werden Rückschlüsse auf die Beeinflussung der Friktion durch die physiologische Zahnbeweglichkeit möglich. Es zeigt sich, daß die gemessenen Reibungskräfte, die an okklusal unbelasteten Zähnen in vivo gemessen werden, sich nich signifikant von den bei geometrisch gleichen Verhältnissen in vitro gemessenen unterscheiden. Allerdings wird nachgewiesen, daß durch willkürliche okklusale Belastung der beklebten Zähne die Friktionskräfte deutlich reduziert werden. Dabei ist zu berücksichtigen, daß die in vivo beklebten Zähne parodontal gesund und fest waren. Es ist deshalb zu erwarten, daß durch die erhöhte Zahnbeweglichkeit im Rahmen einer Multibandbehandlung und zusätzliche Kräfte auf die Bögen beim Essen die bei einer festsitzenden Behandlung auftretenden Friktionskräfte noch geringer sind als hier gemessen.SummaryThis study compared frictional forces which occurred in vivo and in vitro. A testing device was used which allowed reproduction of friction measurements carried out on upper central incisors of volunteers under laboratory conditions with the bracket fixed immovable. By this means changes of friction due to physiological tooth mobility and occlusal load of the bonded teeth could be investigated. While the friction measured in vitro with immovable brackets and in vivo without occlusal load did not differ significantly, additional tooth movement by occlusal load resulted in significant reduction of friction magnitude. It should be kep in mind that the mobility of those teeth investigated was absolutely normal, while it is usually increased during orthodontic treatment. Due to this effect and influences resulting from chewing various kinds of food, it can be estimated that the frictional forces occurring with orthodontic treatment are even smaller in comparison to in vitro experiments with immovable brackets.

Clinical evaluation of a new technique for interdental enamel reduction.

Abstract: 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.Zusammenfassung: Zahngrößenreduktion durch Beschleifen der Approximalflächen (Strippen) ist ein in der Kieferorthopädie gebräuchliches Verfahren. In dem Bemühen, perfekt glatte Schmelzoberflächen zu erzielen, wurden bereits etliche Methoden gründlich untersucht und immer wieder verbessert.In der vorliegenden In-vivo-Studie wurde mittels Rasterelektronenmikroskopie (REM) das morphologische Ergebnis eines Verfahrens untersucht, bei dem die Schmelzreduktion mit einer oszillierenden perforierten Diamantscheibe erfolgte und die nachfolgende Politur mit zwei Sof-Lex-XT-Scheiben geschah. Diese Technik wurde bei 32 Patienten mit einem Durchschnittsalter von 15,5 Jahren angewendet. Insgesamt wurden 296 Approximalflächen behandelt und anschließend Replikas für die rasterelektronenmikroskopische Untersuchung angefertigt. Die rasterelektronenmikroskopischen Befunde zeigten, dass mehr als 90 % der bearbeiteten Approximalflächen gut oder sehr gut poliert waren; der polierte Schmelz war somit glatter als unbehandelte Zahnoberflächen. Das untersuchte Verfahren erforderte pro Approximalfläche einen Zeitaufwand von 2,2 Minuten und erwies sich somit als klinisch praktikabel. Gleichzeitig war es sicher und komfortabel für den Patienten, indem es Lippenretraktoren überflüssig machte und das Verletzungsrisiko trotzdem sehr klein war.

Validity of palatal superimposition of 3-dimensional digital models in cases treated with rapid maxillary expansion and maxillary protraction headgear.

Objective The purpose of this study was to evaluate the validity of the 3-dimensional (3D) superimposition method of digital models in patients who received treatment with rapid maxillary expansion (RME) and maxillary protraction headgear. Methods The material consisted of pre- and post-treatment maxillary dental casts and lateral cephalograms of 30 patients, who underwent RME and maxillary protraction headgear treatment. Digital models were superimposed using the palate as a reference area. The movement of the maxillary central incisor and the first molar was measured on superimposed cephalograms and 3D digital models. To determine whether any difference existed between the 2 measuring techniques, intra-class correlation (ICC) and Bland-Altman plots were analyzed. Results The measurements on the 3D digital models and cephalograms showed a very high correlation in the antero-posterior direction (ICC, 0.956 for central incisor and 0.941 for first molar) and a moderate correlation in the vertical direction (ICC, 0.748 for central incisor and 0.717 for first molar). Conclusions The 3D model superimposition method using the palate as a reference area is as clinically reliable for assessing antero-posterior tooth movement as cephalometric superimposition, even in cases treated with orthopedic appliances, such as RME and maxillary protraction headgear.