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ZusammenfassungDigitale Prozessketten sind heute fester Bestandteil moderner Zahnmedizin und können bei komplexen Versorgungen mit konventionellen Abläufen zu teildigitalen Workflows kombiniert werden. Durchbissregistrate eignen sich dabei für die Modellzuordnung im Artikulator. Ziel dieser Studie war es, ein scanbares Bissnahmesilikon (Registrado Scan [RS], VOCO GmbH) und Vergleichsmaterialien (Registrado Xtra [RX] und Registrado Clear [RC], VOCO GmbH) hinsichtlich der Genauigkeit zu untersuchen. Dafür wurden bei insgesamt 40 Proband*innen Registrate durchgeführt, und mittels farbsensitivem Intraoralscan wurden intraorale angefärbte Kontakte als Referenz dokumentiert. Ober- und Unterkiefermodelle der Proband*innen wurden im Artikulator in Okklusion gebracht und digitalisiert. Die Abweichung der sich ergebenden Kontaktpunkte auf den Modellen zur intraoral erhobenen Referenz wurde in einer 3-D-Software vermessen.Es konnte gezeigt werden, dass sich die Werte in den Gruppen RS (0,52 ± 0,56 mm), RX (0,55 ± 0,53 mm) und RC (0,58 ± 0,53 mm) nicht signifikant voneinander unterscheiden (p ≥ 0,136). Das scanbare Material kann demnach sowohl in volldigitalen, in teildigitalen und auch in konventionellen Workflows angewendet werden.

A defined surface roughness is important for the adhesive bonding of veneering ceramic to zirconia frameworks. Thus, we investigated the effects that sandblasting has upon the surface roughness and residual stress of zirconia. So as to achieve well-defined blasting parameters and also generate highly reproducible results; a custom-made, automated sandblasting machine was constructed (based on a 3D-printer construction kit). Thirty-two samples (measuring 30 mm × 35 mm × 0.2 mm) were cut from densely sintered 3Y-TZP blanks and then ground with a 45 µm grinding disc. After undergoing regeneration firing, the samples were sandblasted with varying working parameters: blasting angle (45°, 60° and 90°); blasting pressure (2 bar, 4 bar and 6 bar); and working distance (0.5 cm, 1.0 cm and 1.5 cm). The sandblasting path was chosen so as to create samples with an even surface roughness. Changes in blasting pressure resulted in the greatest changes in the surface roughness, the highest surface roughness values were achieved with sandblastings perpendicular to the sample surface. Furthermore, a correlation was found between the mean surface roughness and the residual stress.

Objectives: The purpose of this in vitro study was to compare the abrasion behaviour of different charcoal toothpastes when brushing with electric toothbrushes on human enamel. Materials and Methods: A self-designed brushing machine was built using six commercially available electric toothbrushes in abrasion chambers. Each chamber was constantly supplied with a toothpaste–water mix. Pieces of human enamel, which were embedded in PMMA, were brushed for 4 h. Before and after brushing, profilometer measurements were performed in order to determine the substance loss due to brushing. Results: The following calculated mean removal values (mean ± SD) were found: (4.6 ± 0.6) µm (Group C: Splat Blackwood), (3.2 ± 0.9) µm (Group D: Curaprox Black is White), (2.3 ± 0.7) µm (Group B: Sensodyne Pro Schmelz), (1.7 ± 0.6) µm (Group A: Water), (1.4 ± 0.6) µm (Group E: Prokudent Black Brilliant). A post hoc Tukey HSD test (p = 0.05) showed that the results for Group A/B/E, Group B/D and Group C each lie within subsets that differ statistically significantly from the other subsets. Conclusions: Within the limitations of this in vitro study, it can be stated that some charcoal toothpastes lead to significantly higher abrasion on human enamel, when brushing with electric brushes. Clinical Relevance: As low-abrasion toothpaste is generally advisable, and some charcoal toothpastes should be viewed critically with regard to their abrasive properties.

The present study reports on the long-term drug release and mechanical properties of bioactive dental filling materials based on chlorhexidine diacetate (CHX) or octinidine (di)hydrochloride (ODH) incorporated in a composite based on dimethacrylates or an ormocer. CHX or ODH were added to a nano-hybrid ormocer (O) and a nano-hybrid composite (C) with the amount of 2 wt% to achieve four matrix-drug combinations: O-CHX, O-ODH, C-CHX, and C-ODH. Drug extraction and release were measured using high-performance liquid chromatography with diode-array detection (HPLC-DAD), while drug distribution was assessed by using energy dispersive X-ray spectroscopy (EDX). Drug release in water at 37°C was observed over 87 d. To determine the material properties, the water absorption, water solubility, flexural strength and hardness were measured and compared to the reference materials. Persistent drug release over 87 d was observed for both ODH-based systems and both ormocer-systems, with the longest duration of activity seen for the O-ODH combination. Persistent drug release was achieved via the loosening of the polymer network indicated via decreasing polymerization enthalpies, enhanced water absorption, and water solubility. As a consequence, the flexural strengths of the materials were reduced. However, surface hardness was hardly reduced. ODH seems to be more adequate than CHX for the design of bioactive dental filling materials based on nano-hybrid ormocer and composites.

With the aim to design bioactive dental restorative material, the present study investigated the influence of the antimicrobial agents chlorhexidine diacetate (CHX) and octinidine (di)hydrochloride (ODH) when incorporated in two different materials. Selected parameters were polymerization enthalpy, short-term drug release, and the effect on Streptococcus mutans as well as human gingival fibroblasts. Samples were made by mixing a nano-hybrid ormocer (O) and a methacrylate-based nano-hybrid composite (C), each with a mass fraction of 2% CHX or ODH. Release profiles and concentrations of active agents from the resins were assessed, and the cell proliferation of human gingival fibroblasts as well as Streptococcus mutans cultured with the eluates were evaluated. The influence on polymerization was assessed by means of differential scanning calorimetry. Both drugs, especially ODH, showed a decreasing effect on polymerization enthalpies associated with a lowered crosslinking degree. At the same time ODH appeared to be released more persistently than CHX. Moreover, ODH was more efficient with regard to bacteria growth inhibition but also more cytotoxic in terms of reduction of cell viability. ODH is deemed more appropriate for application in a dental resin-based drug delivery system, because of the more persistent drug release than seen for CHX.

Implant restoration is one of the basic treatments in dentistry today, yet implant loss from occlusal overload is still a problem. Complex biomechanical problems such as occlusal overload are often analyzed by means of the finite element method. This numerical method makes it possible to analyze in detail the influence that different loading situations have upon implants and tissues, which is a key element in optimizing these dental procedures. This study was designed to investigate the stress distribution in peri-implant bone of a single-tooth implant crown using the finite element method. The load was applied indirectly via an occluding tooth through a three and five contact setup into the implant crown. The friction coefficient values between the crown and antagonist were varied between 0.1 and 1.0. Additionally, three crowns with cusp inclinations of 20°, 30° and 40° were modeled. Non-linear contact computations indicated that an increase in friction changed the direction and magnitude of contact forces, which also led to reduced stresses in the bone. Furthermore, the stress magnitudes were higher when cusps of a greater inclination were used. The intensity of stress alterations was strongly dependent on the distribution and number of contacts, and the contact force vector. In maximum intercuspation, a resulting axial load due to well-distributed contacts prevented high stresses in bone even with high cusp inclinations and low friction. Therefore for long-term clinical success, particular attention should be paid to occlusal adjustment so as to prevent oblique loading onto dental implant restorations.

Zusammenfassung Einführung Ziel dieser Studie war es, bei 5 verschiedenen Implantatsystemen mit Innen- oder Außenverbindung die Mikrospaltgröße zwischen Implantat und Abutment vor und nach mechanischer Belastung im Mikro-CT zu untersuchen. Material und Methode Die Probekörper wurden in einer zylindrischen Form in Polyurethan eingebettet. Die entsprechenden Abutments wurden im Anschluss mit Drehmoment laut Herstellerangaben fixiert. Die Probekörper wurden mit 1 × 106 Zyklen im Kausimulator mit einer Kraft von 200 N mechanisch belastet. Von jedem Implantat wurden vor und nach der Belastung Aufnahmen im Mikro-CT bei einer Auflösung von 2 µm angefertigt und hinsichtlich einer Veränderung der Mikrospaltgröße an der Fügefläche untersucht. Ergebnisse Unter den Belastungsbedingungen von 200 N konnte bei einem der Implantatsysteme mit Außenverbindung eine Veränderung der Fügestelle zwischen Implantat und Abutment beobachtet werden, keine Veränderung wurde bei den Implantatsystemen mit Innenverbindung sowie mit der zweiten untersuchten Außenverbindung festgestellt. Schlussfolgerung Mechanische Belastungen können die Mikrospaltgröße zwischen Implantat und Abutment beeinflussen. Der Verbindungstyp der Komponenten scheint dabei einen entscheidenden Einfluss auf die Größe des Fügespalts zu haben.

Objectives This single-blinded randomized clinical trial evaluated the effect of adjuvant oral irrigation in addition to self-administered oral care on prevalence and severity of peri-implant mucositis. Material & methods After randomization, patients suffering from peri-implant mucositis were assigned to the following: Group 1 (control) received oral hygiene instruction following a standardized protocol, including a sub- and supramucosal mechanical debridement. Group 2 and 3 additionally were instructed to use an oral irrigator with either water or 0.06% CHX solution. One implant per patient was considered for examination. Clinical examinations included Probing Depth, Bleeding on Probing (BOP-positive sites), and Modified Plaque and Gingival Index. A surrogate variable (mucositis severity score) was applied measuring severity of disease. Statistical analysis included linear regression models and sensitivity analysis. Results Sixty periodontally healthy patients were examined for presence and severity of peri-implant mucositis. 70% of all patients reached complete resolution of disease after 12 weeks. The prevalence of peri-implant mucositis after 12 weeks was 50% in group 1, 35% in group 2, and 5% in group 3. Average BOP-positive sites were reduced in all groups after 12 weeks (mean change from baseline: group 1: -1.5; group 2: -1.8; group 3: -2.3). Conclusion Within the limits of the study, adjuvant use of an oral irrigator with 0.06% CHX in addition to mechanical biofilm removal and oral hygiene instruction can reduce the presence and severity of peri-implant mucositis after 12 weeks.

Camphorquinone (CQ) is by far the most widely used visible-light photoinitiator in biomedical applications. Despite the fact that CQ is well established and has a good clinical acceptance, photoinitiating systems based on CQ have some drawbacks in particular poor water solubility and low photoreactivity. Here the synthesis and testing of a new camphorquinone derivative are described. Carboxylated-camphorquinone (CQCOOH) was synthesized using ketopinic acid as the starting material. The chemical structure of CQCOOH was verified by 1 H-NMR, 1 H– 13 C-COSY-NMR, FT-IR, mass spectroscopy, and UV–visible spectrophotometry. CQCOOH was used with an amine coinitiator and diphenyliodonium chloride (DPIC) accelerator as a visible light induced photoinitiating system for the preparation of hydrogels. CQCOOH exhibits a significantly higher photoreactivity compared to CQ with the same amine-DPIC system. Already after 5 s exposure time, the polymer crosslinked with the CQCOOH-amine-DPIC system to form a hydrogel. Furthermore, higher crosslink density and better mechanical properties are observed compared to those hydrogels prepared with the CQ-amine-DPIC system. Experiments measuring the activity or integrity of cells (MTT and LDH assay, respectively) were performed to investigate the compatibility of the photoinitiating system components with human gingival fibroblast (HGF). According to these experiments neither CQCOOH, l -arginine nor N-phenylglycine as amine coinitiators have toxic effects even in high concentrations. In contrast, HGF cell viability is considerably decreased at DPIC-concentrations higher than 0.25%.

The performance of biomaterials is often compromised by bacterial infections and subsequent inflammation. So far, the conventional analysis of inflammatory processes in vivo involves time-consuming histology and biochemical assays. The present study employed a mouse model where interferon beta (IFN-&beta, ) is monitored as a marker for non-invasive rapid detection of inflammation in implant-related infections. The mouse model comprises subcutaneous implantation of morphologically modified titanium, followed by experimental infections with four taxonomically diverse oral bacteria: Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Treponema denticola (as mono culture or selected mixed-culture). IFN-&beta, expression increased upon infections depending on the type of pathogen and was prolonged by the presence of the implant. IFN-&beta, expression kinetics reduced with two mixed species infections when compared with the single species. Histological and confocal microscopy confirmed pathogen-specific infiltration of inflammatory cells at the implant-tissue interface. This was observed mainly in the vicinity of infected implants and was, in contrast to interferon expression, higher in infections with dual species. In summary, this non-invasive mouse model can be used to quantify longitudinally host inflammation in real time and suggests that the polymicrobial character of infection, highly relevant to clinical situations, has complex effects on host immunity.

PURPOSE Fractures, occlusal adjustments, or marginal corrections after removing excess composite cements result in rough surfaces of all-ceramic FPDs. These have to be polished to prevent damage of the surrounding tissues. The aim of this study was to evaluate the roughness of zirconia, silicate-ceramic, and composite after polish with different systems for intraoral use. MATERIALS AND METHODS Each set of 50 plates was made of zirconia, silicate-ceramic, and composite. All plates were ground automatically and were divided into 15 groups according to the treatment. Groups Zgrit, Sgrit, and Cgrit received no further treatment. Groups Zlab and Slab received glaze-baking, and group Clab was polished with a polishing device. In the experimental groups Zv, Sv, Cv, Zk, Sk, Ck, Zb, Sb, and Cb, the specimens were polished with ceramic-polishing systems "v", "k", and "b" for intraoral use. Roughness was measured using profilometry. Statistical analysis was performed with ANOVA and Scheffe-procedure with the level of significance set at P=.05. RESULTS All systems reduced the roughness of zirconia, but the differences from the controls Zgrit and Zlab were not statistically significant (P>.907). Roughness of silicate ceramic was reduced only in group Sv, but it did not differ significantly from both controls (P>.580). Groups Cv, Ck, and Cb had a significantly rougher surface than that of group Clab (P

Korrekturen der Kieferrelation bei vollbezahnten Patienten stellen oft eine Herausforderung dar. Dieser Beitrag beschreibt mogliche Ursachen fur fehlerhafte Kieferrelationen bei vollbezahnten Patienten und erlautert anhand von Fallbeispielen Herangehensweisen und Behandlungsmoglichkeiten in solchen Situationen.

Die vorliegende Studie beschaftigt sich mit der Oberflachenqualitat von Glas- und Zirkoniumdioxidkeramik nach Politur mit diamantversetzten Silikonpolierern. Dafur wurden Messungen im Profilometer durchgefuhrt und es wurden rasterelektronenmikroskopische Aufnahmen erstellt. Es konnte gezeigt werden, dass durch die Polituren klinisch vertretbare Oberflachenqualitaten erreicht werden konnen, deren Rauigkeit im Bereich naturlichen Zahnschmelzes liegt.

Peri-implant infections from bacterial biofilms on artificial surfaces are a common threat to all medical implants. They are a handicap for the patient and can lead to implant failure or even life-threatening complications. New implant surfaces have to be developed to reduce biofilm formation and to improve the long-term prognosis of medical implants. The aim of this study was (1) to develop a new method to test the antibacterial efficacy of implant surfaces by direct surface contact and (2) to elucidate whether an innovative antimicrobial copolymer coating of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate (VP:DMMEP 30:70) on titanium is able to reduce the attachment of bacteria prevalent in peri-implant infections. With a new in vitro model with semi-coated titanium discs, we were able to show a dramatic reduction in the adhesion of various pathogenic bacteria (Streptococcus sanguinis, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis), completely independently of effects caused by soluble materials. In contrast, soft tissue cells (human gingival or dermis fibroblasts) were less affected by the same coating, despite a moderate reduction in initial adhesion of gingival fibroblasts. These data confirm the hypothesis that VP:DMMEP 30:70 is a promising antibacterial copolymer that may be of use in several clinical applications.

In almost all finite element (FE) studies in dentistry, virtual forces are applied directly to dentures. The purpose of this study was to develop a FE model with non-linear contact simulation using an antagonist as force transmitter and to compare this with a similar model that uses direct force transmission. Furthermore, five contact situations were created in order to examine their influence on the peri-implant bone stresses, which are relevant to the survival rate of implants. It was found that the peri-implant bone stresses were strongly influenced by the kind of force transmission and contact number.

The aim of the study was to compare the WHO-Five Well-Being Index (WHO-5) with the Oral Health Impact Profile-49 (OHIP-49) questionnaire as screening tools to detect psychological comorbidity in TMDs.A TMD group (92 patients, 42.8 ± 17.1 yrs) and a control group (90 patients of the Department of Prosthetic Dentistry, 38.9 ± 10.1 yrs) completed the WHO-5 and the OHIP-49 questionnaire.The patients with TMD reported significantly greater OHIP-49 sum scores than controls (47.5 ± 34.7 vs. 7.7 ± 12.1; p 0.001). The mean raw score of the WHO-5 was significantly less, with 45.6 ± 20.6 points for patients with TMD than the 73.2 ± 15.6 points found for controls (p 0.001). The OHIP sum score and the WHO-5 raw score were significantly associated (r = 0.705, p 0.001). Both instruments exhibited excellent internal consistency (Cronbach's α = 0.967 and 0.883, respectively).WHO-5 proved to be an effective and economic screening instrument to detect psychological comorbidity in TMDs. Implementing WHO-5 in standard care could contribute to more individualized interdisciplinary psychotherapy and/or functional therapy.

Diese In-vitro-Studie vergleicht in 2 Versuchsreihen die manuelle Herstellung von Kompositinlays mit der CAD / CAM-Herstellung. In beiden Versuchsreihen wurden jeweils 10 Inlays hergestellt und in eine metallische MOD-Urkavitat eingepasst. Die Passungsgenauigkeit wurde anhand mikroskopischer Fotografien von Silikonrepliken der Zementfuge ermittelt. Es wurden signifikant bessere Passungsgenauigkeiten bei manuell hergestellten Inlays (p

In dieser In-vitro-Studie wurde der Einfluss kunstlicher Alterung auf die Verbundstabilitat zwischen ZrO 2 -Keramik und Komposit nach Konditionierung mit einem ZrO 2 -Primer untersucht. Zum Vergleich wurden Proben durch Silanisieren, Anrauhen oder Kombinationen beider Vorgange behandelt. Alle Proben wurden im Wasserbad gealtert und Thermowechselbelastungen unterzogen. Es zeigte sich eine signifikant hohere Stabilitat nach Anwendung des ZrO 2 -Primers als nach den anderen Oberflachenvorbehandlungen.

PURPOSE Temperature increase of 5.5 ℃ can cause damage or necrosis of the pulp. Increasing temperature can be caused not only by mechanical factors, e.g. grinding, but also by exothermic polymerization reactions of resin materials. The aim of this study was to evaluate influences of the form material on the intrapulpal temperature during the polymerization of different self-curing resin materials for temporary restorations. MATERIALS AND METHODS 30 provisonal bridges were made of 5 resin materials: Prevision Temp (Pre), Protemp 4 (Pro), Luxatemp Star (Lux), Structure 3 (Str) and an experimental material (Exp). Moulds made of alginate (A) and of silicone (S) and vacuum formed moulds (V) were used to build 10 bridges each on a special experimental setup. The intrapulpal temperatures of three abutment teeth (a canine, a premolar, and a molar,) were measured during the polymerization every second under isothermal conditions. Comparisons of the maximum temperature (TMax) and the time until the maximum temperature (tTMax) were performed using ANOVA and Tukey Test. RESULTS Using alginate as the mould material resulted in a cooling effect for every resin material. Using the vacuum formed mould, TMax increased significantly compared to alginate (P

PURPOSE To evaluate the load at fracture and influence of artificial aging of posterior teeth occlusal veneers ("table tops") made of two different ceramics. MATERIALS AND METHODS A total of 80 table tops were produced from feldspathic ceramic (VM) and zirconia-reinforced lithium silicate ceramic (CD) using computer-aided design/computer-assisted manufacturing (CAD/CAM). Half of the specimens from each ceramic were aged prior to the load test. RESULTS Mean ± standard deviation (SD) load at fracture was significantly higher for CD (1,571.1 N ± 297.0 N) than for VM (573.6 N ± 86.4 N) (P < .001). After aging, load at fracture increased significantly to 1,819.0 N (± 310.6 N) for CD and to 745.2 N (± 168.3 N) for VM. CONCLUSION The use of zirconia-reinforced lithium silicate ceramic for molar nonprep table tops should be uncomplicated according to the high load-at-fracture values. Mechanical stability of either ceramic is not compromised by aging.

Zirkoniumdioxidgeruste fur Vollkeramikbrucken wurden mithilfe von Kopierfrasverfahren hergestellt und verblendet. Zusatzlich wurden Geruste aus einer CoCr-Legierung gegossen und keramisch verblendet. Im Belastungstest versagten die Vollkeramikbrucken vorrangig durch Gerustbruch und die Metallkeramikbrucken in erster Linie durch Frakturen der Verblendkeramik. Hinsichtlich der klinischen Belastbarkeit unterschieden sich die Vollkeramikbrucken und die Metallkeramikbrucken nicht voneinander.

Background: Biofilm formation on trans-gingival implant surfaces is a common reason for local inflammation of the peri-implantary tissue and can lead to implant loss. The aim of the current in situ study was to evaluate biofilm formation on titanium, gold alloy and zirconia abutment materials directly in the trans-gingival region. Materials and Methods: Specimens were attached to implant healing abutments and were inserted in 8 patients for 14 days. Confocal laser scanning microscopy was used to measure biofilm height and surface coverage. Results: Titanium showed a mean biofilm height of 10.8 μm and a surface coverage of 26.5%. For gold alloy, a height of 14.6 μm and coverage of 27.3% was found. Zirconia had a biofilm height of 2.7 μm and coverage of 10.5%. No statistically significant difference between the three materials was found. However, zirconia tended to form less biofilm than the other materials. Conclusion: All three materials seem to be suitable for the use as abutment material. Zirconia appeared to have the most favourable biological and aesthetic properties.

In the current in vitro study, the fracture stability of anterior crowns with zirconia cores of different designs was investigated after applying different veneering techniques. Four groups of zirconia cores (n = 10 in each group) were produced using a computer-aided design/computer-aided manufacturing (CAD/CAM) process. Cores with a standard cervical design were veneered using the layering technique (CCL) or the press-over technique (CCP). Further cores were designed with a porcelain shoulder, where the cervical margin of the zirconia core was reduced by 1 mm. These cores were also veneered using the layering technique (PSL) or the press-over technique (PSP). All crowns were cemented onto metal teeth and loaded until fracture in a universal testing machine. Chipping or fracture of the core was found to occur for CCL at 919±265 N (mean ±SD), for CCP at 798±226 N, for PSL at 739±184 N, and for PSP at 734±209 N. anova did not show significant differences between the four groups. For CCL and CCP, fracture lines ran in a mesio-distal orientation. For PSL and PSP, fracture lines ran into the porcelain shoulder. In summary, the use of a porcelain shoulder can be recommended with zirconia crowns in combination with either the layering or the press-over veneering technique.

Purpose Plasma activation of hydrophobic zirconia surfaces might be suitable to improve the bond strength of luting materials. The aim of this study was to analyze the influence of nonthermal argon-plasma on the shear bond strength (SBS) between zirconia and different combinations of 10-MDP adhesive systems and luting composites after artificial aging. Materials and methods Two hundred forty Y-TZP specimens were ground automatically with 165 µm grit and water cooling. Half of the specimens received surface activation with nonthermal argon-plasma. The specimens were evenly distributed into three groups according to the adhesive systems ([Futurabond U, Futurabond M, Futurabond M + DCA], VOCO GmbH, Germany, Cuxhaven) and into further two subgroups according to the luting materials ([Bifix SE, Bifix QM], VOCO GmbH). Each specimen underwent artificial aging by thermocycling and water storage. SBS was measured in a universal testing machine. Statistical analysis was performed using ANOVA and Scheffe procedure with the level of significance set to 0.05. Results Surface activation with nonthermal plasma did not improve the bond strength between zirconia and the tested combinations of adhesive systems and luting materials. The plasma-activation trended to reveal higher bond strength if the self-etch luting material (Bifix SE) was used, irrespective of the adhesive system. Conclusion Plasma-activation seems to be suitable to improve bond strength between zirconia and self-etch resin materials. However, further research is necessary to identify the influence of varying plasma-parameters.

Purpose In literature, many studies compare survival rates of different types of FPDs. Most of them compared restorations, which originated from one university, but from different clinicians. Data about restoration survival rates by only one experienced dentist are very rare. The aim of this study was to evaluate the survival rate of allceramic FPDs without the blurring effects of different clinicians. Materials and methods 153 veneeredzirconia FPDs were observed for follow-up. 22 patients received 131 single crowns and 22 bridges. Because of the different bridge lengths, one unit was defined as a restored or replaced tooth. In total, 201 units were included. Only the restorations performed by the same clinician and produced in the same dental laboratory from 2011 to 2016 were included. Considered factors were defined as "type of unit", "type of abutment", "intraoral region", and "vitality". Modified UHPHS criteria were used for evaluation. Statistical analysis was performed using cox-regression. Results 189 units (94.0%) showed no kind of failure. 5 chippings (2.4%) could be corrected by intraoral polishing. 4 units (1.9%) exhibited spontaneous decementation. These polishable and recementable restorations are still in clinical use. Chippings or decementations, which lead to total failure, did not occur. One unit was completely fractured (0.5 %). Biological failures (caries, periodontitis or periimplantitis) did not occur. The statistical analysis of the factors did not reveal any significant differences. Conclusion Modern all-ceramic FPDs seem to be an appropriate therapy not only for single restorations but for complex occlusal rehabilitations.

Objectives Erosive attack on enamel leads to a bulk material loss and a partial demineralisation at the lesion body. This zone of softened enamel has a reduced physical stability and large interprismatic porosities. The aim of the current study was to measure the degree of demineralisation with respect to the content of calcium and inorganic phosphorus in softened enamel using ultrasonication and chemical analysis. The erosive demineralisation was to be compared with demineralisation in caries. Methods Erosion of 10 polished human enamel samples was performed in 0.3% citric acid adjusted to pH 3.2 at 35 °C in a slowly stirred solution, each in a volume of 15 ml. After erosion the softened enamel was removed by ultrasonication in 2 ml of deionised water and enamel crystals were dissolved by adding 220 μl of 1 M HCl. Substance loss was measured profilometricaly after erosion and after ultrasonication. Surface size of eroded enamel was measured thus volume loss could be calculated. Calcium and phosphate ion concentration in the solutions were measured after ultrasonication. Results Citric acid erosion caused a mean substance loss of 16.0 μm (SD 2.5 μm) and further enamel softening of 2.4 μm (SD 1.5 μm). The degree of demineralisation of softened enamel, in comparison the original mineral content, was 62% for calcium and 64% for inorganic phosphorus was calculated. Conclusion The high degree of demineralisation shown in the current study explains the instability of softened enamel even against mild physical impact.

The aim of the current study was to access the prevalence of depression among patients with Temporomandibular Joint Disorder (TMD) compared to patients with no current TMD.Patients (92) and controls (90) answered questionnaires on subjective pain, severity of chronic pain, jaw disability, emotional well-being and depression, and a clinical examination was performed.Temporomandibular Joint Disorder patients reported higher disability of jaw function, compared to controls (p0.001). The myoarthopathy subgroup (67.4%) had slightly more jaw disability than the myopathy subgroup (p0.05). While 51% of TMD patients reported poor emotional well-being, only 7.8% of controls were affected (p0.001). Clinical symptoms of depression were reported by 16% of TMD patients and not in the controls (p0.001). Among TMD patients, a higher prevalence of depression was observed in the myopathy subgroup.A regular screening for psychological problems, using standardized questionnaires, should be integrated in clinical examination of TMD patients.

Enamel erosion and softening are based on chemical processes which could be influenced by many factors including temperature and acid flow rate. Knowledge of the influence of these variables could have relevance to research experiments and clinical outcomes. Both parameters were investigated using an ultrasonication and profilometry method to assess erosion depth and surface softening of enamel. The influence of temperature was studied by eroding polished human enamel samples at 4, 20, 35 or 50 degrees C for 2 h. Secondly, different liquid flow conditions were established by varying acid agitation. Additionally, a slow laminar flow and a jet of citric acid, to simulate drinking through a straw, were applied to specimens. Erosion depth increased significantly with acid temperature from 11.0 microm at 4 degrees C to 35.8 microm at 50 degrees C. Surface softening increased much more slowly and plateaued at 2.9 microm to 3.5 microm after 35 degrees C. A strong dependence of erosion on liquid flow was revealed. In unstirred conditions only 8.6 microm erosion occurred, which increased to 22.2 microm with slow stirring and 40.9 microm with fast stirring. Surface softening did not increase correspondingly with its largest extent at slow stirring at 3.4 microm.The implication of these data are: first, the conditions for erosion experiments in vitro or in situ need to be specified for reliable comparisons between studies. Secondly, erosion of teeth by soft drinks are likely to be influenced both by the temperature of the drink and individual drinking habits.

In axial computed tomography it is possible to measure the intercondylar angle at the intersection of the longitudinal axes of the condyles. Published values range from 131 to 165 degrees. This angle was determined here in two groups of patients with (n = 22) and without (n = 12) temporomandibular joint dysfunction. A third group of children (n = 12) aged 4-9 years was included to investigate any age-related change in the angle. In the group of healthy individuals, a range of 105 to 165 degrees was found, with a mean intercondylar angle of 139 degrees. In the group with temporomandibular joint dysfunction the mean angle was 143 degrees with a range from 85 to 170 degrees. No statistically significant relation could be shown between intercondylar angle and joint dysfunction. In the group of children the mean angle was 138 degrees with values ranging from 90 to 180 degrees. No significant differences could be demonstrated among the groups. The absolute value of the intercondylar angle seems to be independent of factors such as sex, age and functional disorders of the joint.

Underdimensioning may adversely affect the clinical use of a crown or bridge. Insufficient dimensions may be due to inadequate modelling or deficiencies caused by the casting process. The dimensions of cast objects are measured mechanically using a calliper. This method has often proved to be insufficient in detecting areas of too small dimensions. This paper presents a non-destructive method of inspecting dental castings using radiography. The occlusal thickness of a random sample of 150 crowns made during regular clinical treatment in our department was inspected mechanically and radiographically. We found that 19% of the crowns were only 0.1 mm thick or less at the thinnest spot, 18% were between 0.1 and 0.2 mm and 9% were between 0.2 and 0.3 mm. In comparison to mechanical examination, radiographic inspection usually showed smaller values.

In the current in vitro study, the fracture stability of anterior crowns with zirconia cores of different designs was investigated after applying different veneering techniques. Four groups of zirconia cores (n = 10 in each group) were produced using a computer-aided design/computer-aided manufacturing (CAD/CAM) process. Cores with a standard cervical design were veneered using the layering technique (CCL) or the press-over technique (CCP). Further cores were designed with a porcelain shoulder, where the cervical margin of the zirconia core was reduced by 1 mm. These cores were also veneered using the layering technique (PSL) or the press-over technique (PSP). All crowns were cemented onto metal teeth and loaded until fracture in a universal testing machine. Chipping or fracture of the core was found to occur for CCL at 919±265 N (mean ±SD), for CCP at 798±226 N, for PSL at 739±184 N, and for PSP at 734±209 N. anova did not show significant differences between the four groups. For CCL and CCP, fracture lines ran in a mesio-distal orientation. For PSL and PSP, fracture lines ran into the porcelain shoulder. In summary, the use of a porcelain shoulder can be recommended with zirconia crowns in combination with either the layering or the press-over veneering technique.