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Die Studie untersucht in einem In-vitro-Modell die Qualität von Wurzelkanalfüllungen in Abhängigkeit von der Abfülltechnik an extrahierten humanen Schneidezähnen mit drei verschiedenen Techniken: Laterale Kompaktion, kalte Single-Cone-Technik und thermoplastische Single-Cone-Technik mit Trägerstiften. Das Abdichtvermögen wird in einem Bacterial-Leakage-Modell untersucht. Anschließend werden in einem Micro-CT dreidimensional die Fehlstellen ermittelt. Abschließend wird im REM die Spaltbildung zwischen Wurzelkanalwand und Wurzelkanalfüllung an Wurzelscheiben überprüft. Statistisch signifikante Einflüsse der untersuchten Füllmethoden auf die Qualität der Wurzelkanalfüllungen werden im Kruskal-Wallis-Test identifiziert.

In dieser Untersuchung wurden die Bakterien- und Farbstoffdurchlässigkeit des Interfaces zwischen präendodontischem Kompositaufbau und postendodontischer Verschlussfüllung in vitro untersucht. Zudem wurde die Spaltbildung am Interface im Rasterelektronenmikroskop (REM) evaluiert. Dafür wurden 6 mm hohe präendodontische Kompositaufbauten (Natural elegance Komposit, Henry Schein) hergestellt, für 28 Tage wassergelagert, trepaniert und mit verschiedenen Vorbehandlungen und Adhäsiv/Komposit-Kombinationen (Restaurationssysteme) gefüllt. Das erste Restaurationssystem bestand aus einem Drei-Schritt-Etch-and-Rinse-System (OptiBond FL, Kerr; OFL) und einem nanomodifizierten Microhybridkomposit (CeramX Mono+, Dentsply DeTrey; CX). Als vereinfachtes Restaurationssystem wurde ein Universaladhäsiv (Clearfil Universal Bond, Kuraray; CU) in Verbindung mit einem Bulk-Fill-Komposit (Tetric EvoCeram Bulk Fill, Ivoclar vivadent; TB) untersucht. Als maximal vereinfachtes Restaurationssystem wurde dasselbe Universaladhäsiv in Verbindung mit einem dualhärtenden Komposit (Clearfil DC Core Plus, Kuraray; CDC) in die Studie einbezogen. Um den möglichen Einfluss einer mechanischen Aufrauhung auf den Verbund zwischen prä- und postendodontischem Komposit zu überprüfen, wurde bei jeweils der Hälfte der Proben der präendodontische Aufbau durch Abstrahlen mit Aluminiumoxidpulver (Al2O3)-Pulver aufgeraut. Der zeitliche Aufwand für die jeweilige Verschlussfüllung wurde dokumentiert. Die Negativkontrollen (NK, N=12) wurden ohne einen Trepanationsschacht hergestellt. Als Positivkontrollen (PK1, N=12) dienten Proben, bei denen kleine Matrizenabschnitte in die Trepanationsöffnungen gelegt wurden, um künstliche Spalten zu erzeugen. Zusätzlich wurden weitere Positivkontrollen (PK2; N=12) hergestellt, bei denen die Trepanationsschächte (wie bei PK1) ohne Vorbehandlung mit Natural elegance Komposit gefüllt wurden, allerdings ohne die Matrizenabschnitte. Zur künstlichen Alterung wurden alle Proben 2.000 Zyklen Thermocycling, 50.000 Zyklen mechanischer Kaubelastung und 28 Tage Wasserlagerung ausgesetzt. Dann wurden die Proben sterilisiert, und die bakterielle Penetration (BL) mittels Enterococcus faecalis wurde innerhalb einer Dauer von 122 Tagen überprüft. Dabei wurden sowohl die Anzahl der bakterienundichten Proben als auch die Dauer bis zur vollständigen Penetration erfasst. Danach wurden die Proben erneut sterilisiert und einer Farbstoffpenetrations-Untersuchung in 1 %iger Fuchsin-Lösung unterzogen, bei der die Proben in zwei Hälften längs gesägt wurden und die Tiefe der Penetration mittels eines Auflichtmikroskops und einer Messsoftware evaluiert wurden. Anschließend erfolgte ein Replizieren der gesägten Proben mit Kunstharz und ein weiteres Quersägen der Proben mit nochmaliger Kunstharzreplikation. Diese Replikas wurden im REM auf Spalten am Interface untersucht. Die Häufigkeiten der BL-positiven und BL-negativen Proben in den einzelnen Versuchsgruppen unterschieden sich nicht signifikant (chi2-Test: p=0,500). Signifikante Unterschiede zwischen den postendodontischen Verschlussmaterialien in Bezug auf die Penetrationsdauer waren zwischen den Gruppen Al2O3-/CU/CDC mit Al2O3-/CU/TB bei p=0,000, Al2O3-/CU/CDC mit PK2 bei p=0,001 und Al2O3-/CU/CDC mit Al2O3+/CU/TB bei p=0,006. Die Farbleakage-Analyse ergab bei allen Proben keine Farbstoffpenetration. Aus diesem Grund wurde dieser Test bei der Auswertung nicht weiter berücksichtigt. Nur bei einem geringen Anteil der Proben waren Randspalten zwischen den prä- und postendodontischen Restaurationen im REM sichtbar (13,7% im Längsschnitt und 15,8% im Querschnitt) unabhängig davon, wie ausgedehnt diese Spalten waren. Der Anteil an sichtbaren Randspalten am Interface war nur sehr gering (Median = 0% bei allen Versuchsgruppen). Dadurch resultierte keine auswertbare Signifikanz, weder in den Längs- noch den Querschnitten der Proben. Aus der Methodik dieser Untersuchung ging hervor, dass Farbleakage- und Bacterial Leakage-Untersuchungen keine Korrelation aufwiesen. Das gleiche galt für die Übereinstimmung zwischen Spaltanalyse und der bakteriellen Penetration. Es gab in dieser Untersuchung keine Restaurationssystem-Vorbehandlung-Kombination, die die bakterielle Penetration innerhalb der 122 Tage vollständig verhindern konnte. Das Anrauen des präendodontischen Aufbaus mittels Al2O3-Pulver vor einer postendodontischen Kompositversorgung brachte in Bezug auf die Bacterial Leakage keinen Vorteil. Die Kombination aus einem Universaladhäsiv (CU) und einem dualhärtenden Aufbaukomposit CDC) schnitt in den Bacterial-Leakage-Tests am schlechtesten ab. Als günstigstes Verfahren in Bezug auf Zeitbedarf, Aufwand und Verzögerung der bakteriellen Penetration stellte sich die Kombination aus einem All-in-One Adhäsiv (CU) und einem Bulk-Fill-Komposit (TB) ohne vorheriges Sandstrahlen des Aufbaus mit Al2O3-Pulver dar.

The aim of this prospective clinical study was to assess the long-term clinical survival rate and the technical and biological complication rates of zirconia-based posterior FDPs.Forty-five patients in need of one or more posterior FDPs received 57 three- to five-unit zirconia-based FDPs. The frameworks were fabricated by means of a prototype computer-aided manufacturing (CAM) system (direct ceramic machining, DCM), first processing zirconia in the white stage. The frameworks were veneered with a prototype veneering ceramic.The FDPs were adhesively placed. At baseline, 6 months, and 1,2, 3, 5, 8 and 10 years of function, the FDPs were examined for technical and/or biological complications. Furthermore, the periodontal health of the abutment teeth (test) and untreated control teeth was analyzed. Statistical analysis was performed applying descriptive statistics, Kaplan-Meier survival and multiple mixed effects regression tests.Twenty-one patients with 26 FDPs were examined at a mean observation time of 10.7 +/- 1.3 years. A total of 16 FDPs were lost to follow-up. Fifteen FDPs had to be replaced due to technical/biological complications; hence, the 10-year survival rate of the FDPs was 67%. Three framework fractures occurred, resulting in a 10-year survival rate for the zirconia frameworks of 91.5%. Chipping/fracture of the veneering ceramic was detected in 16 FDPs over 10 years (complication rate 32%). A significant correlation of the span of the FDPs and the incidence of chipping was observed: 4- and 5-unit FDPs had a 4.9 times higher probability for chipping than 3-unit FDPs. Marginal discrepancy/degradation was found in 90.7% of the FDPs over 10 years. At 11 of the FDPs (complication rate 27%), secondary caries occurred. No difference of the periodontal health was found around test and control teeth.The zirconia frameworks exhibited very good long-term stability. However, the zirconia-based FDPs frequently exhibited problems such as marginal deficiency or chipping of the veneering ceramic. Both problems may be associated with the prototype status of the system.

In the third part of this review of laboratory testing, methods of testing adhesive systems are evaluated. Test set-ups that are used to analyze the restorative material in combination with the adhesive system are presented. Currently, there is no standardized protocol available for the evaluation of adhesives. This complicates any direct comparisons of values between different testing institutes. Therefore, the statistically evaluated ranking of the different adhesives is more important than mean values. Depending on the testing institute, a correlation between bond strength measurements and clinical outcomes may exist. Qualitative analysis of adhesive/tooth interaction can help explain the functioning of a system, but the depth of penetration of the adhesive cannot predict bond strength. Indirect bond measurements or analyses of the interactions of adhesive and composite materials, such as dye penetration or marginal analysis, do not correlate or correlate only partially with clinical findings. Adhesive systems should be tested in vitro and compared to a well-known standard adhesive before they are used in the clinic. Water storage of specimens for several months before testing increases the predictability of the bonding performance of the tested adhesive.

Epiphany/Resilon and GuttaFlow are newly developed methods for obturation of the root canal system. Epiphany/Resilon is a thermoplastic, synthetic polymer-based root canal filling material which enables the bonding to the dentin root canal wall during root canal obturation. GuttaFlow is a cold flowable filling system for the obturation of root canals, combining sealer and gutta-percha in one product. The purpose of this study was to assess the leakage of the Epiphany/Resilon or GuttaFlow root canal filling compared with lateral condensation of gutta-percha. For this study were used 45 human extracted teeth, chemo mechanically prepared, divided into three groups and obturated with gutta-percha/AH Plus, Epiphany/Resilon and GuttaFlow. For dye penetration all teeth were centrifuged for three minutes at 30 g in 2% methylene blue and dissolved in 65% nitric acid for 3 days. The extracted methylene blue was determined with Photometer. Root Canal fillings with Epiphany/Resilon showed less dye penetration than lateral condensation of gutta-percha and GuttaFlow. Epiphany/Resilon is ideally suited as a root canal filling material.

One of the main treatments in dental practice is the exchange of restorations due to secondary or residual caries. Thereby, only restorations indeed infected with secondary or residual caries should be renewed. The aim of the study was to check the validity of different criteria for the replacement of fillings. Three hundred seventeen replacements of dental restorations were evaluated retrospectively by using an examination form. Different clinical parameters were correlated with the finding of caries after removal of the old restoration. Clinical findings were differentiated between caries soft to probing, caries only stainable with caries detector and caries-free cavities. Sixty-seven percent of the cavities showed caries that could be probed, 16.1% were just stainable with caries detector and 17% were caries-free. In general, results of previous replacements of fillings were a valid criterion. Other indicators for caries-free cavities were properly placed fillings with a correctly reconstructed morphology, fillings without marginal defects, a low age of the filling and a positive impression of the patients' general hygiene. Indicators for cavities with secondary caries were marginal gaps, pain within the respective section of the jaw, a high number of filled surfaces and a bad impression of the general hygiene. Systematic diagnostic criteria should be adopted in decision making on replacement of fillings in order to avoid new restorations of caries-free cavities.

The advantages of minimally invasive dentistry are well established, especially for direct restorations. However, when it comes to indirect restorations traditional tooth preparation designs are still advised by most manufacturers. The purpose of this in vitro study was to investigate the ability of a CAD/CAM machine (Cerec) to produce minimal preparation designs and identify limiting parameters. Crown preparations based on the proposed minimal design were made using phantom teeth. Gauged burs (Intensiv SA; Meissinger, Germany) and a paralleling device were used to standardize preparations. Cerec Scan/Cerec 3D was used for scanning and designing. The materials tested were a resin composite (Paradigm MZ100, 3M ESPE) and two ceramic materials (ProCAD, Ivoclar Vivadent, and VITA Mark II, Vita). The morphology, marginal integrity, and materials' integrity were examined. The design was subjected to an interactive process as material property limitations and constraints imposed by the system became apparent. SEM, optical microscopy, and transillumination were used for the qualitative control of the crowns. The results of this study showed that only the composite material produced acceptable crowns with intact margins for the minimal design initially proposed. The ceramic materials required a wider preparation design in order to produce acceptable crowns. Within the limitations of this study, the null hypothesis was partially rejected as it was found that only the composite material could produce acceptable crowns based on the proposed minimal design. It was also found that the materials' properties, the milling mode, and cutting instruments are determining factors in establishing the extent of the minimal preparation.

It was the aim of this prospective clinical splitmouth investigation to evaluate the survival rate and long-term behavior of all-ceramic partial coverage restorations (PCR) on molars. Pressed ceramic (IPS e.max Press) and CAD/CAM made (ProCAD) PCR were compared. 80 vital molars of 25 patients were restored with all-ceramic PCR (40 IPS e.max Press* and 40 ProCAD*). All PCR were adhesively luted with a light-polymerizing composite (Syntac*/Tetric*) (*Ivoclar-Vivadent AG, Schaan, Liechtenstein). The ProCAD PCR were produced with Cerec 3 and Cerec Inlab CAD/CAM system (Sirona Dental Systems, Bensheim, Germany). IPS e.max Press PCR were heat-pressed following the lost-wax IPS-Empress method. Clinical recall was arranged in average 8, 14, 20 and 28 months after cementation of the restoration. PCR were classified by USPHS criteria. The prospective survival rate of ProCAD PCR was 97% and 100% for IPS e.max Press PCR after an observation period of 24 months. After fracture, one ProCAD restoration had to be replaced after nine months. The clinical accuracy of the marginal fit of ProCAD PCR and IPS e.max Press PCR was recorded "Alfa". Limitations were recognized with respect to the color matching of both types of PCR ("Bravo").Within the limits of the present clinical results, the tested all-ceramic materials IPS e.max Press und ProCAD seem to be indicated for partial coverage restorations on molars.

The present in vitro study investigated the sealing of retrograde fillings compounded of two different cements in consideration of cracking after root-end preparation of resected dental roots using diamond-coated ultrasonic retrotips. Root-end cavities were prepared in 32 resected roots using diamond-coated ultrasonic retrotips. The samples were divided into two groups. The first group was filled using zinc-oxide cement (Super-EBA-Cement), the second with mineral-trioxide-aggregate (Pro Root MTA). After resection, root-end preparation and retrograde filling, the samples were analysed using macro-zoom photography and scanning electron microscopy. The sealing quality of the filling materials was detected through dye penetration test. The average degree of penetration of the samples filled with Super-EBA-Cement was 2.19 and of the samples filled with Pro Root MTA 0.44 respectively. Accordingly the sealing of Pro Root MTA in vitro is superior to the sealing of Super-EBA-Cement. Retrograde conditioning of resected roots with ultrasonic retrotips represents an efficient and sparing alternative to conventional root-end preparation techniques.

The precondition for introducing medical products, e.g. new filling materials, in the European Union is their safety, not their clinical reliability. The latter arises from longitudinal studies and is assessed on the basis of available standards or, if not existant, on formulated quality guidelines. In the case of the specific products Ariston Liner and Ariston pHc (Vivadent, Schaan, FL), designed as an amalgam substitute, the material combination did not correspond to the Swiss standard 2 of restorative dentistry. Although after a short-term application testing on caries free premolars the pulp and dentin were free from inflammation and bacteria, the material combination clinically failed within the 18 months control period with a cumulative failure rate of 16.1% due to marginal caries. After six months of function the subjectively assessed sensitivity tended to increase. Gap formations and porous zones were detected in the composite-tooth-interface in vitro as well as in vivo. Neither the lining, designed to ensure the passage of cations and anions out of the filling material, nor the concept of an adequate caries protective effect proved successful. Marginal caries and hypersensitivity of teeth were the main reasons for the replacement of this amalgam substitute. The specific material combination was withdrawn from the market. As long as laboratory methods cannot substitute clinical evaluations, the introduction of new materials or systems into the market should be supported by short-term clinical studies and the further quality assessment should result from intermediate to long-term longitudinal studies. In this respect guidelines are valuable, such as the Swiss guidelines concerning materials as amalgam substitute.

Changes in restorative techniques and the development of new restorative materials have allowed the use of more conservative cavity preparations. Important questions are: What are the consequences of incomplete removal of caries-affected dentin? What are the bond strengths of adhesives to demineralized enamel and dentin? The non-invasive management of carious lesions with intact tooth surfaces in a manner that will bring about some remineralization offers a viable and superior alternative to conventional restorations. The bond strengths of adhesives to demineralized enamel seem to be similar to that on normal enamel. None of the modern filling technologies can guarantee the arrest of the carious process. The complete removal of the infected dentin is, however, still necessary irrespective of the restorative material used.

The objective of this study was to compare the apical leakage in root canal filled, apicectomised and retrogradely filled maxillary single rooted premolars with two canals of type II configuration. For this purpose the root canals of 51 maxillary type II premolars were shaped to size ISO #55, followed by a step-back preparation to size ISO #80. Subsequently, all teeth were obturated by means of lateral condensation and randomly divided into three groups, 17 teeth each. Group I was used as a control, whereas in group II and III an apicoectomy was performed. Retrograde glass ionomer restorations (Ketac Fil) were placed additionally in group III. The specimens were exposed to methylene blue for 24 hours, then cross-sectioned, and the deepness of dye penetration was measured. Data were analyzed and tested for significant differences between the various groups (Mann-Whitney test; alpha = 0.05). The teeth in group II showed the lowest mean dye penetration. The differences were statistically significant, if compared to group I (p0.001) and group III (p0.001). The dye penetration in group I was significantly lower than in group III (p = 0.024). In teeth with lateral canals, the mean dye penetration was higher (3,557 microns +/- 1,337 microns) than in teeth without lateral canals (3,096 microns +/- 1,931 microns). The teeth in group III showed a circular dye penetration in nearly all cases. For clinical purposes, the application of retrograde glass ionomer fillings must be considered very critically.

The removal of polymerized excess resin cement around adhesive inlays is very time consuming and often tooth-destructive. In this study we evaluated, if brushing away of the unset resin cement produced any marginal imperfections. It was found that this procedure caused underfilled margins especially in the occlusal portion of the inlay margins. For this reason the use of this method to remove excess resin cement is not recommended.

The marginal adaptation of six composites and one resin based inlay system was investigated. For all fillings maximum stress increased with time. Three days after insertion maximum stress increased up to more than 450 N for almost all fillings.

Butt joint, plain and round beveled MOD cavities were prepared in extracted human molars. Composite resin inlays (SR-Isosit) were fixed adhesively and analysed by quantitative SEM-evaluation after thermocycling and mechanical load application. The marginal adaptation of the inlays differed significantly depending on the type of cavosurface preparation. Best results with a high percentage of perfect margins not only before but also after in vitro load application were obtained with cavities prepared with rounded bevels.

Ceramic inlays have shown good marginal seal as long as the margins of the cavities are located in enamel. The purpose of this study was to investigate the marginal seal of ceramic inlays with the cervical margins situated in dentin and to determine the effectiveness of dentin bonding agents. Sintered ceramic inlays were adhesively luted either without dentin bonding agents or with the use of Gluma or Miragebond. After thermocycling and incubation in a colored dye the penetration depth of the dye was measured on sequential sections. The used dentin bonding agents did not improve marginal seal. The glass ionomer cement base was able to prevent further penetration in most of the cases when deep leakage occurred. Unless a tight marginal seal in dentin can be achieved, the indication for adhesively luted inlays must be limited to cavities with margins located in enamel.

In this study class I cavities were prepared in extracted human molar teeth. The cavities were treated with composite restorations or metal inlay restorations. After thermal and occlusal stress, the marginal seal was tested using a dye-penetration-test. The results were evaluated as follows: Grade 0-Grade 1 = sealed or almost sealed restoration; Grade 2-Grade 3 = evident or clearly distinct loss of marginal adaptation. The study showed following results: 1 Composite restorations (Heliomolar) proved seven out of ten cases to be sealed or almost sealed (Grade 0 or Grade 1). Three out of ten cases showed a dye penetration at Grade 3. 2 Metal inlays (Degulor M) that were cemented with zinc phosphate cement, were rated in none of the cases as sealed. They showed in nine out of ten cases a dye penetration at Grade 2 or 3. With dye-penetration-tests conclusions can be made regarding the marginal seal of restorations. However, clinical application of a restorative material should not be made dependent on this criteria alone.

This in vitro study assessed the marginal behavior of the "Kulzer"-inlay using two different resin luting agents (Adhesive cement resp. Tulux-Cem). SEM-evaluation after combined mechanical and thermal loading revealed significant differences in the marginal seal of the inlays depending on the luting composite resin used. "Kulzer"-inlays luted with Adhesive cement showed of rate a excellent margins of more than 90% even after in vitro load application, while the rate of perfect margins were less than 80% for "Kulzer"-inlays inserted with Tulux-Cem.

The marginal situation of class I restorations is determined by the intensity of the light used for curing. In all composites the use of an intensive light-source (Osram HBO 100) leads to marginal gaps. This effect was demonstrated in three composites cured with light sources that are commonly used in practice.

Esthetic restorations for class V lesions extending into root dentin often show marginal discoloration after some time. In this clinical study the long term quality of glass ionomer cement and "sandwich" restorations was compared with each other. In 19 patients 83 class V lesions with the apical margin in dentin were restored with glassionomer cement (I: Fuji II/G-C Dental; II: Ketac Fil/ESPE) or with a glass ionomer liner (III: Lining Cement/G-C Dental; IV: Ketac Bond/ESPE) and laminated with a composite. Where necessary the margins were prepared apically with a butt joint. The observation period between placement and last follow-up check varied between 18 and 44 months. Modified Ryge criteria were used for the clinical assessment of 77 restorations. Marginal quality was assessed in the SEM using replicas. 15.8% of the "sandwich" type and 5% of the glass ionomer cement restorations were lost. All restored teeth remained vital. Clinically the best marginal quality was found with a glass ionomer cement (II) whereas only two thirds of the sandwich restorations and the other glassionomer cement (I) had perfect margins. In the SEM the glassionomer cements had significantly less marginal openings than one of the sandwich restorations (III).

It was the objective of this in-vitro field study to evaluate the marginal fit of the In-Ceram system (Vita). All the materials applied in this system were compared with each other under the aspect of their dimensional behavior to determine the influence of this factor on die adaptation. The mean value of the marginal fit of the In-Ceram restorations on the master models was 12 (+/- 10) microns. The PFM bridges showed marginal openings of 9 (+/- 10) microns. The values on the patient models were 38 (+/- 12) microns for In-Ceram, and 44 (+/- 19) microns for PFM. This increase had been anticipated because of the grain size of the Harvard Cement. The dimensional changes of the materials involved were in great harmony. At least one coat of die spacer is necessary to compensate for the contraction of the ceramic and the expansion of the special plaster. Two paints are recommended for crowns and three for bridges. Careful shoulder or chamber preparation is required to create smooth surfaces.

The clinical relevance of the dimensional behavior of six different gamma-2-free silver amalgam products was examined in comparative in vitro and in vivo trials. Dye penetration tests, roughness measurements, and inspection of the marginal fit using a scanner electron microscope all showed that the results of the in vivo and the in vitro trials were in good agreement and that there was no significant difference between the various products tested, despite the fact that they differed both in morphology and in composition. Copalite exerts a favorable influence on the marginal fit of amalgam restorations, not only in laboratory trials, but also clinically. The results obtained show that the behavior of an amalgam with respect to changes in volume is not the sole criterion by which its quality is to be judged. Amalgams with a pronounced contraction tendency will seal the marginal gap with their corrosion products (SnCl). Here copalite serves as a temporary stand-in. There was no leakage of metal ions from the restoration into the dentin for any of the products tested, including those with a high copper content.

In a study of the influence of the proximal box shape on the marginal fit of Cerec inlays, MOD cavities were prepared in 10 extracted teeth. One box was prepared with sharp edges as recommended by Mörmann (1989), the other was conventionally U-shaped. The width of the marginal gap was measured with a microscope at five different points. The results showed with high significance that the marginal gap of the U-shaped box preparation is smaller. It is recommended to use conventional U-shaped proximal box preparations for Cerec-inlays, too.

Direct and indirect composite and ceramic inlays exhibit a space between inlay and tooth, which is filled with a luting composite resin. The aim of the present study was to evaluate the influence of the width of this space upon the quality of the marginal seal of the inlay system. The marginal quality of class II-inlays with small (0.2 mm) and large (0.4 mm) spaces was examined using quantitative SEM analysis and dye penetration. Regular class-II composite fillings served as controls. After thermal and mechanical loading the composite inlays with the wider composite layer showed more marginal gaps than both groups of ceramic inlays. The ceramic inlays did not show a significant deterioration of the margins. The least amount of dye penetration was observed in ceramic inlays with a wider composite layer at the interproximal cavity wall. Composite fillings showed more dye penetration than inlays.

In an in vitro study 32 ceramic restorations were constructed using the Cerec system and adhesively fixed in cavities prepared in extracted teeth with Dual Cement according to the supplier's instructions. The restored teeth were then histologically prepared and the joints between cement and inlay morphometrically evaluated at eight defined sites. The measurements showed average values of 118 microns with a standard deviation of 53 microns. It is particularly interesting to note the extremely great range of variation between the lowest and the highest value. The measured widths of the joints must be considered as a weakness of the system, because clinically they may result in wash-outs and material collapses in the long run. So far, no long-term studies have been conducted yet to investigate this effect.

Three different types of ceramic inlay materials (Dicor, Biodent-Inlay-Keramik, Cerec) were evaluated for precision of reproduction and dimensional fit. The findings of this study revealed that laboratory-made restorations displayed satisfactory characteristics of reproduction except for the edges. Furthermore the initial fit of these materials was comparable to the fit of gold restorations. The Cerec-inlay system by contrast displayed insufficient reproduction characteristics especially at lines, angles and edges. The average marginal gap of Cerec inlays measured was 154 microns. General guidelines for cavity preparations based on the present findings are discussed.

The advantages of air vents in the production of extensive cast gold inlays and partial crowns were examined in an in vitro study aimed at reducing the occurrence of open margins in the proximal surfaces. The results of this study with a total of 44 casts showed that a closer marginal fit is achieved by the use of additional air vents.

Inlays and partial crowns made with a new titanium casting system were studied for open margins. The rather heterogeneous results do not satisfactorily stand comparison with conventional methods and thus the clinical application of this system does not seem to make sense.

16 butt joint (Group A) and 16 beveled (Group B) class I cavities were prepared in extracted molars and filled with two hybrid composite resin materials using the enamel etching technique. Replicas were obtained before and after thermocycling (TC) and a computerized quantitative margin analysis was carried out in the SEM. Statistical analysis revealed significant differences (p less than 0.01) between the two groups only after TC. Group B showed significantly less marginal openings than Group A (A: 50.7%, B: 8.4%) after TC. Class I cavities for hybrid composite resin materials should be beveled.

The disadvantage of conventional metal ceramic restorations seems to be the loss of transluszenz and transparency in thin ceramic layers, on behalf of Aumatic-foil an improved aesthetic image is possible. Foil-technique enables the production of metal ceramic crowns with a compressive and shearing forces allowing the appliance to single crown in clinic use. In vitro measurement of the marginal leakage show a sufficient adaptation.

In this in vitro study the wear resistance and abrasiveness against opposing enamel cusps, marginal adaptation and radiopacity of two experimental composite resin materials were tested. The results indicated that in particular the fine particles hybrid showed low wear. The radiopacity of both materials tested was just acceptable. Marginal adaptation was insufficient in both cases, the reason being most probably the low viscous bonding agent and the polymerization shrinkage. Therefore both test materials are not suitable for use as direct posterior composite fillings.

30 inlays were produced exactly by manufactures instruction using the SR-Isosit composite. Before cementation the marginal gaps of the inlays extended to 280 microns occlusal resp. to 350 microns gingivoproximal. After insertion the thickness of the luting composite ranged from 40 to 400 microns occlusal resp. from 40 to 470 microns gingivoproximal. Dye penetration test indicated that only 43.7% of the inlays had a good marginal behaviour after storage in water over a six month period. Particularly remarkable was the insufficient junction between the luting composite and the highly polymerized inlay.

The marginal quality of a crown or a filling is of great importance for the success or failure of any restoration. Secondary caries and a marginal periodontal disease are the result of defects in this very critical area. This should be mainly caused by a plaque accumulation, which is determined by the adaptation, the contour, the placement and the quality of the surface of the restoration margin. With respect to the irritation of the marginal periodontium specific cytotoxic effects of each material might be a cofactor too.

Six acrylic tooth stumps were prepared for an evaluation of the marginal quality of crowns produced by spark erosion. Four different methods were used for preparation of the crown margins. Each stump had two different margin preparations. The crowns were fabricated with the aid of spark erosion. Serrated sections were then made for an analysis of marginal defects. The results have shown that the mean size of marginal openings is highly dependent on the preparation method used.

Cervical lesions in 38 patients were restored using composite resins (n = 57), the "sandwich-technique" (n = 64) or glassionomercement (n = 66). Immediately following insertion and 4, 8, and 12 months later, the restorations were examined clinically and in the SEM. Two composite fillings and one filling each of the two other types of restoration were lost. After one year the quality of the dentinal margins of the composite restorations was statistically (p less than 0.05) inferior to the two other methods. Margin quality in enamel was rated superior (p less than 0.05) with glassionomercement as against the other materials. Clinically, the composite filling yielded poorer results regarding marginal integrity and discoloration, although in general they showed superior esthetics. In restoring cervical lesions the use of glassionomercements or the "sandwich-technique" has definite advantages over composite fillings. For the evaluation of new restorative materials and techniques, SEM should be used in addition to clinical examinations.

When cemented, directly and indirectly fabricated posts and cores should have good retentive properties and passive fit. Both features require adequate accuracy of fit. The results published in this paper demonstrate that, when using the NPM alloy Dentitan, this is requirement is met only by the direct fabrication method. Without subsequent fine adaptation the mean width of the marginal openings was 87 microns as against 248 microns in indirectly fabricated posts. The interactions in the area of the real interfaces between stump and posts and their effects on the cervical margin are discussed.

The quality of the occlusal margins of 58 computer-machined ceramic inlays (Cerec) was examined by SEM. The adhesion of the luting composite to enamel and to the inlay appeared more of less stable. However, the wear of the composites was substantial and more pronounced in Brilliant and in Microfill pontic C than it was in Heliomolar.

The marginal adaptation of partial crowns with different types of finish line preparations was determined by means of dye penetration tests. The best marginal sealing was found for the featheredge-like preparation, followed by the shoulder preparation and the chamfer preparation with or without bevel. The scanning electron microscopic evaluation revealed that a finishing of the restoration margins during the setting of the luting material resulted in a better marginal sealing than a finishing after the cementation.

Investigations to the corrosive behavior in artificial saliva, to shear-bond-strengths and to the formation of gaps in composite-alloy-compounds produced by using the SILICOATING-PROCEDURE show the better properties of the alloy GISADENT NCS1 respectively to NCA. The clinical results are in agreement with these facts, but it is necessary to pay attention to the small changes in the technological process.