10-Year Clinical Comparative Study of Ceramic and Composite Veneered Metal Crowns.

The rejection of composite veneerings in fixed partial dentures is primarily caused by the inadequacy of the bonds between the metal framework and the composite veneering. The development of improved veneering composites necessitates an investigation of their clinical suitability compared with ceramic materials. Nineteen patients with at least two suitable, adjacent natural teeth for crowning were treated with 64 high noble alloy crowns. The adjacent crowns were veneered with ceramic (IPS inline) and composite materials (SR Adoro). Seven follow-up examinations were carried out over a period of 10 years. The crowns were investigated for mechanical defects, periodontal parameters, and discolorations. The survival rates of the ceramic veneered metal crowns (CeMCs) and composite veneered metal crowns (CoMCs) at the 10-year follow-up were 87.1 and 87.9%, respectively. The success rates of the crowns after 10 years were 83.9% for CeMCs and 51.5% for CoMCs (log-rank test, p = 0.009). No significant differences between the groups were found in the periodontal parameters (Kruskal-Wallis one-way analysis of variance, ANOVA p ⟩ 0.05). After 10 years, discoloration patterns of the two materials differed significantly (Mann-Whitney-U-test, p = 0.017). Thus, despite the improvements associated with CoMCs, CeMCs remain the gold standard for veneered metal crowns.

Retentive characteristics of individual and prefabricated polyvinylsiloxane overdenture attachments: alternative treatment options for geriatric patients.

OBJECTIVES: Stud attachments are often too adhesive and too susceptible to damage for use in geriatric patients, especially when implants are angulated. This study aimed to evaluate alternative anchoring systems comprising individual and prefabricated polyvinylsiloxane (PVS) attachments. MATERIALS AND METHODS: A total of 182 specimens with individual PVS (IPVS) attachments (Shore hardness [SH] 25, SH50, SH65], prefabricated PVS (PPVS) attachments (SM green, yellow, and red), and Locator attachments (LR blue) were fabricated (n = 7 per group). Retention force was measured using the following parameters: insertion/removal (100, 200, 500, 1000, and 5000 cycles), thermal undulation (10,000 cycles at 5-55 °C; one implant per specimen), implant angulation (0°, 5°, and 10° convergence and divergence; two implants per specimen), and artificial saliva. RESULTS: Insertion/removal and thermal undulation caused no changes in retention force in SM green and IPVS subgroups; conversely, LR blue, SM red, and SM yellow attachments exhibited significant decreases in retention force of up to 66% (all P ≤ 0.001). Implant angulation produced relevant changes in retention force only in LR blue attachments. Artificial saliva caused a general decrease in retention force. CONCLUSIONS: Retention force of low-retentive PVS attachments proved to be comparatively immune to dislocation and thermal undulation, as well as to implant angulation up to 10°. CLINICAL RELEVANCE: Low-retentive PVS attachments could be a treatment option if reduced denture retention is required and/or if angulated implants are in place. Clinical studies are necessary to evaluate the materials' durability under oral conditions.

Axonal Injury with Persistent Neuropathy following Popliteal Nerve Block for Cheilectomy Surgery.

Peripheral nerve blocks are often used for foot and ankle surgery. The occurrence of persistent neurological symptoms thereafter is very rare. Preventive strategies pose no guarantee and uncovering true etiology is often complicated. We discuss a case in which a young, healthy patient developed nerve damage after an uneventful popliteal block and cheilectomy. Nerve conduction studies revealed axonal injury in the distribution area of the sciatic nerve. The neurological symptoms persisted for more than 12 months, emotionally affecting the patient greatly. Patients will primarily report to the orthopedic surgeon, for whom cooperation with anaesthesia and neurology is of importance. Anesthetic involvement probably improves patient satisfaction during complication management.

Overbite and overjet are not related to self-report of temporomandibular disorder symptoms.

Overbite and overjet, especially high or low values, have been found in some studies to be associated with temporomandibular disorders (TMD). This study evaluates the relationship between overbite/overjet and three TMD self-report measures (pain, joint noises, limited mouth-opening). Subjects were from two population-based cross-sectional studies (3033 subjects). After adjustment for age and gender, high or low values of overbite were not associated with an increased risk of self-reported TMD pain as compared with a reference category of a normal overbite of 2 to 3 mm (-8 to -1 mm, odds ratio = 0.36, 95% confidence interval = 0.05-2.76; 6 to 15 mm, odds ratio = 1.08, 95% confidence interval = 0.68-1.72). Similar non-significant results were found for overjet and TMD pain, and for the association of overjet/overbite and joint noises or limited mouth-opening. This study provides the strongest evidence to date that there is no association between overbite or overjet and self-reported TMD.

Complete dentures fixed on dental implants: chewing patterns and implant stress.

Electrognathographic measurements on 18 patients with implant-attached mandibular complete dentures showed larger and more stable chewing patterns compared to their former dentures without implants. Strain gauge measurements revealed mechanical stress acting on the implants even during the fixation of the bar. In addition to simulating the periodontal ligament, the intramobile element (IME) of the IMZ system compensated minor, clinically undetectable mismatches inherent with technical procedures (casting, soldering). Although the implants are loaded with tensile and compressive stress, tensile stress dominated during the chewing process. The implants were also loaded during swallowing. This load reached half of the value of the chewing loads.

[The antimicrobial effect of an alginate with an antiseptic admixture]. / Untersuchungen zur antimikrobiellen Wirkung eines Alginates mit antiseptischem Zusatz.

Attempts to simplify impression disinfection lead to the production of an aseptic alginate impression material (Blueprint asept, De Trey/Dentsply, Konstanz, Germany). This study describes the aseptic properties of this new type of impression material. The in-vitro part of the experiments showed a reduction of Staphylococcus aureus by 6 and of Pseudomonas aeruginosa by 4 log steps after 60 min, and of Candida albicans by at least 3 log steps after 15 min of exposure. Under in-vivo conditions oral bacteria residing on the impression surfaces were reduced by nearly 4 log steps. Although the aseptic properties of the material were demonstrated, the biological acceptance, dimensional stability and compatibility with gypsum have to be tested in further studies.

[Tensile strength of short-fiber-reinforced temporary plastics]. / Biegefestigkeit kurzfaserverstärkter Provisorienkunststoffe.

Glass fibers added to temporary crown and bridge material (Proviso-Blend, Blendax) by 5% to the weight increased the tensile strength of the acrylic resin by 38%. The increase was even greater when carbon fibers were added (50%), but the resin discoloured to a greyish shade. The results were less spectacular with Dentalon Plus (Kulzer), and the experiment did not work with Protemp (Espe). The amount of improvement in tensile strength depended on the type and geometry of the fiber and of the fiber concentration. Neither the properties of the polished surface of a fiber-reinforced acrylic nor adverse effects of such fibers possibly swallowed by the patient are investigated as yet.

EEG findings in an eleven-year-old girl with mercury intoxication.

An 11-year-old female was seen at our outpatient clinic with a broad variety of symptoms that were due to elemental mercury intoxication. Electromyography and sequential electroencephalography findings obtained at days 2, 36, 88 and 148 are described. The patient was treated with chelation therapy during which she clinically improved considerably. A profound decrease in urinary mercury concentration occurred as well as normalization of the electroencephalogram.

Gingival reaction on crowns with cast and sintered metal margins: a progressive report.

Sintered metals have been developed recently for the construction of metal ceramic crowns (Degusint U). An unbalanced, randomized double-blind study was conducted to compare the gingival response to artificial crowns with sintered noble metal margins and cast noble metal margins (Degudent U) by measuring the sulcus-fluid-flow rate (SFFR) in highly motivated patients. In a prior study marginal opening of 20 microns were recorded for cast metal crowns, whereas two sintered metal crowns had marginal openings of 40 microns. Three metal ceramic crowns (Renaissance, Degusint U, and Degudent U for the copings and VMK 68 porcelain) with subgingival margins were prepared and fabricated for 12 intact natural teeth. The SFFR was measured for teeth with artificial crowns and adjacent natural teeth after provisional insertion of each crown. Significantly elevated SFFRs were recorded for all artificial crowns compared with the adjacent natural teeth, but there were no variations recorded for the different types of crown margins.

[Disinfection of dental impressions]. / Abdruckdesinfektion.

The need for disinfection of dental impressions is generally postulated. While many disinfectants for elastomeric impression materials have been recommended for at least ten years, several authors recently described suitable disinfectants for alginate impressions. Disinfectants for reversible hydrocolloid materials are in the phase of practical testing, and show promising first results. Under practical and scientific aspects further investigations are necessary to evaluate standards and standardized testing procedures.

[Radiosterilization of impressions]. / Strahlensterilisation von Abformungen.

Dimensional stability and mechanical properties of addition-silicone impression materials were tested after sterilisation with gamma rays. There were no clinically relevant changes to not sterilized materials.

Disinfection of pumice.

Pumice is a potential source of infection for the dental technician and of cross-contamination between different dentures and patients. In this study, the number of microorganisms in two different combinations of pumice and disinfectant was compared with a conventional mixture of pumice and water. The results revealed that under practical conditions the mix of Steribim (pumice containing benzoic acid added by the manufacturer) with water reduced the number of bacteria by 99% compared with a mix of a conventional pumice and water. The addition of an antiseptic product that contained octenidine as active agent to conventional pumice reduced the number of microorganisms by 99.999%.

[Wettability and accuracy of reproduction of impression materials]. / Benetzbarkeit und Wiedergabegenauigkeit von Abformmassen.

Traditional elastomeric impression materials, four recently developed "hydrophilic" silicones and a hydrocolloid have been tested for their accuracy of reproduction by use of indirect measurements via plaster dies and for their wettability by means of the sessile drop method. The new silicones are reproducing the original model as exactly as the traditional elastomers. The impression techniques have a stronger influence on the results than the impression materials. Although the new silicones are more hydrophilic than the traditional elastomers, they do not reach the wettability of a hydrocolloid. The results of the indirect measurements and the results of the contact angle measurements are corresponding to the results of other investigations and to literature data of bubble counts of plaster dies made of different impression materials.

In vivo color stability of resin-veneered telescopic dentures: a double blind pilot study.

STATEMENT OF PROBLEM: Discoloration is a major disadvantage of resin veneers on telescopic dentures. In vitro color measurements with large and flat samples of resin veneer composites have been published, but no in vivo data are available. PURPOSE: This study describes the discoloration of resin veneers in vivo by use of spectrophotometry and the L*a*b* system of the Commission Internationale de L'Eclairage (CIE). METHODS: In a clinical evaluation of this technique, two composite veneer materials were compared in 18 patients. RESULTS: Both brands discolored significantly after 1 year. While L* and a* were not changed significantly, b* and the total color difference delta E increased by approximately 2 units each year. No statistically significant differences were found between the materials.

The marginal fit of cemented galvanoceramic crowns.

Galvanoceramic restorations were constructed for five extracted teeth. Following cementation, the margins were photographed (magnification X 33) and the prints mounted to produce a continuous image of the entire margin. Cement film thickness measurements were made at 0.1-mm intervals. The five cemented restorations were then embedded in resin, sectioned longitudinally, and examined under a microscope (X 125). The mean gap at the restoration margin, as measured by each technique, was 18 microns and 19 microns, respectively. These results were consistent with the clinical impressions of cemented galvanoceramic restorations completed at the University of Tübingen.

[Color stability of light curing composites]. / Farbbeständigkeit lichtpolymerisierender Komposite.

Eight commercial and two experimental light cured composite have been tested for color stability after experimental aging. Color differences were measured by computer-controlled spectrophotometry and expressed in terms of L*A*B* color coordinates (CIELAB). Although three composites with a high content of anorganic filler showed the best color stability and the material with the lowest anorganic filler content showed the greatest discoloration, there was no strong correlation between the amount of anorganic filler on the one hand and color stability after experimental aging on the other.

[Properties of a measuring system for digital occlusion diagnosis]. / Messeigenschaftenr eines Systems zur digitalen Okklusionsdiagnostik.

The properties of a new digital technique of demonstrating and quantifying occlusal contacts (T-scan) were tested in vitro the sensor foil used was 95 microns in thickness and had approx. 1350 measuring points. When a given force was applied at the same point on one foil several times in sequence, the readings were highly reproducible. Applying the same force at different points on the same foil and at points on different foils, however, failed to bring about reproducible results. The reasons for this lack of reproducibility and possible modifications are discussed.

Effects of attachment type on the mobility of implant-stabilized overdentures--an in vitro study.

PURPOSE: To stabilize overdentures, a wide range of attachments to implants is suggested. Although there is evidence that denture stability is an important factor for patient satisfaction, there are no data on how these attachments may reduce denture mobility. It was the purpose of this study to compare the effects of different types of attachments on the mobility of implant-stabilized overdentures in vitro, designing a measurement device that could also be used in vivo. MATERIALS AND METHODS: On an acrylic model with 2 implants in the canine areas, magnets were fixed to one of the implant abutments. Four Hall-effect devices were attached to the denture opposite the magnet, which allowed contact-free measurements of denture movements. RESULTS: In vitro experiments loading an overdenture showed very small, largely insignificant differences in denture mobility when different bar or ball attachments were used. Geometric aspects of load application were more important than the choice of attachment. CONCLUSION: The measurements gave no guide to the choice of an attachment. The similarity of the attachments must be confirmed by in vivo measurements.

[Effects of caries-preventive fluoride gels on dental ceramics]. / Der Einfluss von Fluorid-Prophylaxe-Gelen auf Dentalkeramiken.

The effects of several fluoride gels on ceramic surfaces (Dicor, Optec, Biodent ceramic and Vita VMK) were tested by SEM and by means of an electrical stylus instrument. After 10 min exposure time an acidulated gel (Oral-B Fluoride-Gel) showed a significant effect, whereas the effect of two non-acidulated gels (Elmex-Gelee, Blend-a-med Fluoride Gel) was not significant. After 24 h exposure time, Elmex and Blend-a-med gel showed an effect, too.