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Objectives To compare oral health-related quality of life (OHRQoL) in patients with either molar replacement by partial removable dental prostheses (PRDP) or with restored shortened dental arches (SDA) over a period of 10 years. Methods In this multi-center RCT, a consecutive sample of 215 patients with bilateral molar loss in at least one jaw was initially recruited in 14 prosthodontic departments. Of those patients, 150 could be randomly allocated to the treatment groups (SDA: n = 71; PRDP: n = 79), received the allocated treatment, and were available for follow-up assessments. OHRQoL was assessed using the 49-item version of the Oral Health Impact Profile (OHIP) before treatment (baseline) and at follow-ups after treatment (4–8 weeks and 6, 12, 24, 36, 48, 60, 96, and 120 months). To investigate the course of OHRQoL over time, we longitudinally modelled treatment and time effects using mixed-effects models. Results OHRQoL substantially improved from baseline to first follow-up in both groups indicated by a mean decrease in OHIP scores of 20.0 points (95%-CI: 12.5–27.5). When compared to the SDA group, OHRQoL in the PRDP group was not significantly different (−0.6 OHIP points; 95%-CI: −7.1 to 5.9) during the study period when assuming a constant time effect. OHRQoL remained stable over the 10 years with a statistically insignificant time effect (p = 0.848). Conclusions For patients requesting prosthodontic treatment for their lost molars, treatments with SDA or PRDP improve clinically relevantly OHRQoL and maintain it over a period of 10 years with no option being superior to the other. Clinical significance Since there was no significant difference between the two treatment options over the observation period of 10 years, and since results have stayed stable over time, patients can be informed that both treatment concepts are equivalent concerning OHRQoL.

Objective This study aimed to investigate the effects of long-term use on the retention force and wear behavior of double crown systems. Methods Based on a common double crown design sixty pairs of telescopic crowns were fabricated and divided into six groups, each consisting ten samples: “Gold standard” cast gold alloy primary and secondary crown (GG) and cast non-precious alloy (NN), computer-aided design (CAD)/computer-aided manufacturing (CAM)-milled zirconia primary crown and galvanoformed secondary crown (ZG), CAD/CAM-milled non-precious alloy primary and secondary crown (CC NN), CAD/CAM-milled zirconia primary crown and non-precious alloy secondary crown (CC ZN) and CAD/CAM-milled zirconia primary crown and polyetheretherketone (PEEK) secondary crown (CC ZP). In the constant presence of artificial saliva, all samples were subjected to 10,000 joining-separation cycles at a velocity of 120 mm/min. Wear was analyzed by reflected light microscopy and confocal microscopy before and after artificial aging. Results Retention force losses were observed in each group after long-term use, with significant losses in the groups ZG and CC ZP (pZG = 0.01, pCC ZP = 0.049). During artificial aging, no significant differences in pull-off force were recorded for groups GG, NN and CC ZN. Regarding wear, merely the Y-TZP primary crowns of the CC ZP group displayed no surface changes. Significance All tested production methods and material combinations seem to be suitable for clinical practice. CAD/CAM technology allows similarly predictable results to be achieved as the gold standard. Confocal microscopy is recommended for surface examinations of double crowns.

Journal of prosthodontic research 64(4), 498-505 (2020). doi:10.1016/j.jpor.2020.01.005, Published by Elsevier, Amsterdam [u.a.]

ZusammenfassungIn einer Welt, in der Ästhetik und äußeres Aussehen immer bedeutender werden, spielt insbesondere die Schönheit der Zähne in den Vorstellungen der Patienten eine dominante Rolle, was sich als Leistungsangebot und auch wesentlicher Bestandteil der meisten Praxishomepages widerspiegelt. Gutes Aussehen steht in direktem Zusammenhang mit einem attraktiven Lächeln und schönen Zähnen und damit einer gesteigerten Lebensqualität.

Purpose This study aimed to compare the long-term outcomes of two different nonimplant treatments in the bilateral shortened dental arch (SDA). Materials and methods In a multicenter randomized controlled clinical trial, patients with complete molar loss in one arch were assigned to one of two different nonimplant treatments. In the partial removable dental prosthesis (PRDP) group, patients were provided with a distal-extension prosthesis retained with precision attachments. In the SDA group, patients were treated according to the SDA concept by preserving or restoring a premolar occlusion. Results Of the 152 treated patients, 82 reached the 10-year examination independent of their dental or prosthetic status. In the intention-to-treat analysis, the survival rates for tooth loss at 10 years were 0.44 (95% confidence interval [CI]: 0.30 to 0.56) in the PRDP group and 0.52 (95% CI: 0.37 to 0.65) in the SDA group. For tooth loss in the study arch, the survival rates were 0.67 (95% CI: 0.52 to 0.78) in the PRDP group and 0.60 (95% CI: 0.45 to 0.73) in the SDA group. The number of teeth lost was higher than expected. In a multivariate analysis using a multiple Cox regression model, the covariates age (unit: 1 year, Hazard Ratio [HR]: 1.033, P = .03) and DMFT value (unit: 1 tooth, HR: 1.121, P = .03) were significant for time to first tooth loss in the study arch. Conclusion The results suggest an overestimation of the influence of the prosthetic management of the bilateral SDA. In treatment decisions, patient preferences should be considered with appropriate weight.

Plaster casts can be digitized with desktop scanners, intraoral scanners, and recently also with cone beam computed tomography (CBCT). The aim of this study was to investigate the accuracy of five different CBCT devices digitizing a plaster cast. A study cast serving as a patient was made using the double mix impression technique, and the impression was poured out with plaster. On the resulting plaster cast, arch length (AL), intermolar width (IMW), and intercanine width (ICW) were measured by a coordinate measuring machine (CMM) (Zeiss O-Inspect 422). The patient cast was then scanned by five CBCT devices - CS 9300, CS 9300 Select, CS 8100 3D (all Carestream), Promax 3D Mid (Planmeca), and Whitefox (Acteon) - in eight scan modes. For each CBCT device, 37 scans were performed. The resulting DICOM data were exported as stereolithographic (STL) data and linearly measured using Convince Premium 2012 (3Shape) software. All measurements were compared to the reference master values of the patient cast. The accuracy measurements showed significant differences among the CBCT devices. The highest accuracy was achieved by Whitefox (IMW: mean ± standard deviation (SD): 5.5 ± 5.7 µm) and CS 9300 (IMW: -15 ± 7.4 µm). Comparable results with less accuracy were shown by CS 8100 3D (IMW: -81.2 ± 7.4 µm) and CS 300 Select (IMW: -82.2 ± 6.6 µm). Significantly lower accuracy was shown by Promax 3D Mid (IMW: -126.1 ± 4.8 µm). Some CBCT devices are suitable for the digitization of plaster casts and show very good clinical accuracy. Dental offices equipped with CBCT devices could digitize plaster casts without the need for additional devices.

The aim of this study was to compare the accuracy of six intraoral scanners as regards clinically relevant distances using a new method of evaluation. An additional objective was to compare intraoral scanners with the indirect digitization of model scanners. A resin master model was created by 3D printing and drilled in five places to reflect the following distances: intermolar width (IMW), intercanine width (ICW), and arch length (AL). To determine a gold standard, the distances were measured with a coordinate measuring instrument (Zeiss O-Inspect 422). The master model was scanned 37 times with the following intraoral scanners: Apollo DI (Sirona), CS 3500 (Carestream Dental), iTero (Cadent), PlanScan (Planmeca), Trios (3Shape), and True Definition (3M Espe), and indirectly digitized with the OrthoX Scan (Dentaurum). The digital models were then measured, and deviations from the gold standard calculated. Significant differences were found between the devices. Among the intraoral scanners, Trios and iTero showed the most accurate results, although CS 3500, True Definition, and Apollo DI achieved comparable results. PlanScan demonstrated the highest deviations from the gold standard, and presented a high standard deviation (SD). Direct digitization revealed comparable (and, in fact, slightly higher) accuracy than indirect digitization. Both indirect digitization and most of the intraoral scanners were therefore demonstrated to be suitable for use in the orthodontic office, with the exception of PlanScan, which did not meet the demands of individual orthodontic treatment.

Summary In a multicentre randomised trial (German Research Association, grants DFG WA 831/2-1 to 2-6, WO 677/2-1.1 to 2-2.1.; controlled-trials.com ISRCTN97265367), patients with complete molar loss in one jaw received either a partial removable dental prosthesis (PRDP) with precision attachments or treatment according to the SDA concept aiming at pre-molar occlusion. The objective of this current analysis was to evaluate the influence of different treatments on periodontal health. Linear mixed regression models were fitted to quantify the differences between the treatment groups. The assessment at 5 years encompassed 59 patients (PRDP group) and 46 patients (SDA group). For the distal measuring sites of the posterior-most teeth of the study jaw, significant differences were found for the plaque index according to Silness and Loe, vertical clinical attachment loss (CAL-V), probing pocket depth (PPD) and bleeding on probing. These differences were small and showed a slightly more unfavourable course in the PRDP group. With CAL-V and PPD, significant differences were also found for the study jaw as a whole. For CAL-V, the estimated group differences over 5 years amounted to 0·27 mm (95% CI 0·05; 0·48; P = 0·016) for the study jaw and 0·25 mm (95% CI 0·05; 0·45; P = 0·014) for the distal sites of the posterior-most teeth. The respective values for PPD were 0·22 mm (95% CI 0·03; 0·41; P = 0·023) and 0·32 mm (95% CI 0·13; 0·5; P = 0·001). It can be concluded that even in a well-maintained patient group statistically significant although minor detrimental effects of PRDPs on periodontal health are measurable.

To investigate the nursing home inhabitants’ perceptions towards oral health care and to determine the actual level of treatment needs. All 114 nursing homes in the Federal State of Saarland, Germany were requested to participate in the study. A standardized questionnaire was utilized to assess patient attitudes and satisfaction with their oral health. The state of oral health and dental treatment needs were evaluated in a clinical examination. Facility response rate was 10.5 %. 170 inhabitants from 12 nursing homes (mean age 81.8 years; 71.8 % women) were involved in the study. The mean decayed/missing/filled teeth (DMFT) index was 24.2; the mean number of missing teeth was 22.96. Most of the subjects (80.1 %) had removable dentures, 48.8 % were edentulous. Over 70 % had not been examined by a dentist during the last year. Only about one third of the senior citizens reported problems with their natural teeth (13 %) or dentures (23.8 %), although the caries morbidity among the dentulous was high (87.6 %) and about half of the dentures (50.1 %) were rated as insufficient. Periodontal treatment was necessary in 65.1 % of the cases. Denture-related stomatitis affected 27 %. Unhygienic dentures were worn by 64.1 % of the subjects; dental hygiene was bad in 63.2 % of the cases. The results of this study revealed a large discrepancy between perceived and actual treatment needs among institutionalized elderly people in Saarland. There is an urgent need for the development of a systematic dental care program for elderly people in the Federal State of Saarland.

Being a secondary outcome in a multicenter randomized controlled trial, the present analysis focused on interdental spacing in the shortened dental arch (SDA). The aim was to evaluate changes in interdental spacing in dependence of two different treatments after an observation period of up to 5 years.Patients were either treated with a partial removable dental prosthesis (PRDP) for molar replacement (PRDP group) or according to the SDA concept aiming at a premolar occlusion (SDA group) in a randomized manner. Interdental spacing in the anterior region was measured with gauges and categorized as "0" (0.1 mm), "1" (0.5 mm), "2" (0.5-1 mm), and "3" (1 mm). The statistical analysis was performed with analysis of variance models followed by linear contrast.Ninety-one patients (SDA n = 41, PRDP n = 50) were included. Changes of interdental spacing were detected in 70.7 % of all cases. A significant difference between the mean score changes was found in the mandible comparing the PRDP group and the SDA group. The respective mean score changes from baseline to 5 years were 0.23 (SD 0.49) for the PRDP group and 0.02 (SD 0.30) for the SDA group (p = 0.023).Major interdental spacing could be observed in neither of the groups. The SDA concept resulted in a slightly better outcome.When deciding whether to replace missing molars, the present results give further support to the SDA concept.

The aim of this in vitro study was to evaluate the influence of different finishing procedures on the wear behavior of zirconia against natural enamel.64 quadratic specimens (10 mm × 10 mm × 2 mm) were cut from a commercial hipped dental Y-TZP ceramic. Four different groups with 16 specimens each were formed according to the following finishing procedures: PZ (polished), RR (fine-grit diamond), GR (coarse-grit diamond), GZ (glazed). Polished specimens of a leucite-reinforced glass ceramic (Empress CAD) were used as a control (GC). The materials were subjected to the Ivoclar wear method (Willytec chewing simulator, 120,000 cycles, 5kg weight) with 80 natural caries-free cusps of first upper molars as antagonists. Wear was analyzed for both the enamel cusps and test specimens by measurement of the vertical substance loss with a laser scanner. Surface roughness was measured by means of a white-light interferometer.The surface roughness was significantly different among the polished, diamond-finished, and glazed ceramic specimens (ANOVA, post hoc Bonferroni p0.05). The results of the one-way ANOVA indicated that the finishing technique significantly affected enamel wear (p0.05). The post hoc test indicated that the specimens finished with the coarse diamond caused significantly higher antagonist wear than the polished ones. Polished zirconia showed the lowest wear of the antagonist enamel, with a mean value of 171.74 (SD = 121.68), and resulted in enamel wear that was not significantly different from that of the glass ceramic control group. No significant linear correlation could be found between pre-testing surface roughness and abrasive wear.If zirconia is used without veneering material for crowns and fixed dental prostheses (FDPs), the surface must be well-polished if occlusal adjustments with coarse diamonds are performed. The polishing step reduces the wear of the opposing enamel.

Objectives The aim of this study was to evaluate the mechanical properties and the subcritical crack growth behavior of a presintered dental Y-TZP (Kavo Everest ZS) and a hot isostatic pressed Y-TZP (Kavo Everest ZH) and to perform life data analysis. Methods For each material 150 bending bars were produced. The initial fracture strength was determined in a four-point bending test. The subcritical crack growth parameters n and A were determined in a dynamic fatigue method at four decreasing loading rates from 110 MPa/s to 0.11 MPa/s in distilled water at 38 °C. For each loading rate Weibull statistics were performed and the Weibull moduli m and characteristic strengths σ 0 were calculated. Using these data, strength–fracture probability–life time (SPT) predictions were derived for 1 day, 1 year, 5 years and 10 years, based on a static crack growth mechanism. Results The “hipped” Y-TZP ceramic exhibited a higher initial strength ( σ c = 1618.18), characteristic strength ( σ 0 = 837.15) and fracture toughness ( K IC = 4.52 MPa/m 1/2 ) than the pre-sintered ceramic ( σ c = 1431, σ 0 = 745.46 and K IC = 3.17 MPa/m 1/2 , respectively). Fatigue parameters, n and A , were 28.5 and 7.97 × 10 −24 for Everest ZH and 30.15 and 5.47 × 10 −20 for Everest ZS. The predicted fracture stress at 5% failure probability for a lifetime of 10 years was 259.34 MPa for Everest ZH and 263.2 MPa for Everest ZS. Conclusions Although the “hipped” Y-TZP showed favorable initial mechanical properties, no significant difference could be found in the susceptibility of both ceramics to subcritical crack growth and their long-term strength.

doi: 10.1111/j.1741-2358.2010.00409.x Dental care and treatment needs of elderly in nursing homes in Saarland: perceptions of the homes managers Objective: To investigate nursing home managers’ perceptions and attitudes towards oral health care and access to dental services for aged care facility residents. Method: Questionnaires containing 28 closed-ended questions were mailed to all 114 nursing homes in Saarland, Germany. Descriptive statistics were calculated for response items. Results: Facility response rate was 39%. None of the nursing homes in this study offered systematic dental health care. Initial dental screening was carried out only in one facility. In 81%, dental examinations only took place if required. Although stationary dental equipment was available only in one home, dental treatment was carried out in 71% of the cases by a dentist in the nursing home. Eighty-four per cent of the homes’ managements rated the state of the dentition of the inhabitants as satisfying. Over half of the managers indicated satisfaction with the know-how of their nursing staff concerning oral hygiene procedures. The most significant barriers to provision of dental care in the facilities according to their managers were staff shortage, lack of interest of the inhabitants and financial concerns. Conclusions: The results of this study showed an urgent need for estimating a programme for systematic dental care for institutionalised elder people in the federal state of Saarland.

Zahnmedizin und Zahntechnik zeichnen sich durch ein vielfaltiges Tatigkeits- und demzufolge heterogenes Expositions-Spektrum der Beschaftigten aus. Mogliche Gesundheitsrisiken sind neben einem dermalen Kontakt zu den unterschiedlichsten Arbeitsstoffen und Sekundarprodukten vor allem durch die Inhalation von Aerosolen, ultrafeinen Stauben bzw. Nanopartikeln gegeben. Eine orientierende Analyse der Partikelanzahlkonzentrationen in den Behandlungsraumen und dem Dentallabor der Universitats-Zahnklinik erfolgte mit dem tragbaren Kondensationspartikelzahler (CPC 3007, TSI), der die Gesamtpartikelanzahl in einem Grosenbereich von 10 bis 1 000 nm in einem Konzentrationsbereich von bis zu 105 pt/cm3 bestimmt. Bei zahnarztlichen Routine-Tatigkeiten zeigten sich im Allgemeinen keine signifikanten Spitzenkonzentrationen. Demgegenuber fanden sich kurzzeitige, uber Sekunden anhaltende Maxima bei der Anwendung von Propan- und Butanhaltigem Kaltespray zur Sensibilitatsprufung, bei intraoraler Applikation von Druckluft oder im Rahmen von Wurzelkanalbehandlungen, bei denen am Behandlungsstuhl offene Flammen Verwendung fanden. Konzentrationen > 400 000 pt/cm3 wurden bei der Bearbeitung von PMMA-haltigen Materialien z.B. im Rahmen der prothetischen Versorgung dokumentiert, die durch eine lokale Absaugung auf 1/20 der initialen Konzentration reduziert werden konnten. Eine gleichzeitige Flussigkeitskuhlung fuhrte ebenfalls zu einer signifikanten Verminderung der Partikelspitzenkonzentration von 167 000 auf 5 700 pt/cm3 beim Frasen von Glaskeramik bzw. von 45 000 auf 7 000 pt/cm3 bei der Verarbeitung von Zirkoniumdioxid-Keramik. Wahrend reprasentativer Tatigkeiten wurden gleichzeitig Partikelproben aus der Raumluft gewonnen, die durch moderne Bildgebungsverfahren (REM) einschlieslich gekoppelter Elementanalyse (EDX) visualisiert und u.a. als Zirkonium-, Gold- und Titanium-Partikel im Nanomasstab verifiziert wurden. Die lediglich bei speziellen und verhaltnismasig selten ausgefuhrten Tatigkeitsablaufen in Zahnklinik und Dentallabor dokumentierten signifikanten Partikelspitzenkonzentrationen bedurfen — insbesondere vor dem Hintergrund eines toxischen Potentials einiger Arbeitsstoffe wie Zirkonium und (Poly-)Methylmethacrylate — adaquater organisatorischer, technischer und personenbezogener Schutzmasnahmen am Arbeitsplatz zur Pravention berufsbedingter Erkrankungen der Atemwege und der Haut.

The aim of the study was to evaluate the influence of fatigue and cementation mode on the fracture behaviour of endodontically treated bovine incisors restored with fiber-reinforced-composite (FRC) posts and crowns. Forty-eight endodontically treated incisors were restored with FRC posts, composite build-ups, and cast crowns. In 16 teeth, each of the posts were cemented conventionally with KetacCem (3M Espe) or adhesively with Panavia F (Kuraray) or RelyXUniCem (3M Espe). One-half of the specimens in each group were subjected to thermal cycling with 10,000 cycles at 5-55°C and mechanical aging, loading the specimens in 1,200,000 cycles with 50 N. Fracture resistance was determined by loading the specimens until fracture at an angle of 45°. The loading test showed that cementation mode and fatigue testing had an influence on the load bearing capability. Before fatigue testing no statistically significant differences between the different cementation modes could be detected. After fatigue testing, conventionally cemented FRC posts lead to statistically significant higher fracture loads compared to adhesively luted posts. Most specimens fractured in a favourable way, independent from the type of cementation.

The objective of this study was to compare the shear bond strength to zirconium oxide ceramic of adhesive-phosphate-monomer-containing (APM) and non-APM-containing (nAPM) luting cements after different surface treatments. nAPM cements: Bifix QM, Dual Cement, Duo Cement Plus, Multilink Automix, ParaCem Universal DC, PermaCem Smartmix, RelyX ARC, Variolink Ultra, and Variolink II; APM cements: Panavia EX, Panavia F2.0, and RelyX UniCem. Groups of ten test specimens were each prepared by layering luting cement, using cylindrical Teflon molds, onto differently treated zirconium dioxide discs. The surface treatments were airborne-particle abrasion with 110 mum alumina particles, silica coating (SC) using 30 mum alumina particles modified by silica (Rocatec System) or SC and silanization. Bifix QM and Multilink Automix were used in combination with an additional bonding/priming agent recommended by the manufacturers. After 48 h of water storage, each specimen was subjected to a shear test. Combinations involving APM-containing cements (14.41-23.88 MPa) generally exhibited higher shear bond strength than those without APM (4.29-17.34 MPa). Exceptions were Bifix QM (14.20-25.11 MPa) and Multilink Automix (19.14-23.09 MPa) in combination with system-specific silane or priming agent, which were on the upper end of shear bond strength values. With the use of the Rocatec system, a partially significant increase in shear bond strength could be achieved in nAPM cement. Modified surface treatment modalities increased the bond strength to zirconium oxide, although the most important factor in achieving a strong bond was the selection of a suitable cement. System-specific priming or bonding agents lead to further improvement.

The aim of the study was to evaluate the influence of fatigue and cementation mode on the fracture behavior of endodontically treated bovine incisors restored with zirconium dioxide posts and crowns. Forty-eight endodontically treated bovine primary incisors were restored with zirconium dioxide posts (Cerapost, Brasseler), composite build-ups, and crowns cast from a chromium cobalt alloy. In 16 teeth, each of the posts was cemented conventionally with KetacCem (3M ESPE) or adhesively with Panavia F (Kuraray) or RelyX UniCem (3M ESPE). One-half of the specimens in each group were subjected to thermocycling with 10,000 cycles at 5-55 degrees C and mechanical aging, loading the specimens at an angle of 45 degrees in 1,200,000 cycles with 50 N. Fracture resistance was determined by loading the specimens until fracture at an angle of 45 degrees to the long axis of the teeth. The loading test showed that neither cementation mode nor fatigue testing had an influence on the load bearing capability. Most specimens fractured in a favorable way, independent from the type of cementation.

Purpose The aim of the study was to evaluate the influence of different posts on the fracture load and fracture mode of endodontically treated premolars with class II cavities and direct composite restorations in an ex vivo setting. Methods Forty-eight single-rooted human premolars were endodontically treated and prepared with standardized MO (mesio-occlusal) cavities. Eight teeth each received either no posts or were restored with titanium screws (BKS), glass fiber posts (DentinPost), or quartz fiber posts (DT Light SL). Sixteen teeth were restored with zirconium dioxide posts (CeraPost). BKS-screws and eight zirconium dioxide posts were cemented conventionally with glass ionomer cement; Panavia F resin cement was used for all others. The specimens were restored with direct composite restorations. Eight sound premolars served as the controls. After thermomechanical fatigue testing, the samples were loaded until fracture occurred at an angle of 45°. All specimens were evaluated for fracture lines. Results The sound teeth showed the significant highest fracture load (792.50 ± 210.01 N). The group restored with quartz fiber posts differed not significantly from the control. In the groups with fiber posts and titanium screws significant higher fracture load values occurred as in the group with direct composite restorations without posts. The groups with fiber posts did not show a more favorable fracture mode than the other groups. Clinical significance The use of an intraradicular post in premolars with class II cavities can significantly increase the resistance towards extra-axial forces.

Introduction The mechanical properties and slow crack propapagation of the all-porcelain system Empress® 2 (Ivoclar Vivadent, Schaan, Liechtenstein) with its framework compound Empress® 2 and the veneering compounds “Empress® 2 and Eris® were examined. Methods For all materials, the fracture strength, Weibull parameter and elastic moduli were experimentally determined in a four-point-bending test. For the components of the Empress® 2 system, the fracture toughness KIC was determined, and the crack propagation parameters n and A were determined in a dynamic fatigue method. Using these data, life data analysis was performed and lifetime diagrams were produced. The development of strength under static fatigue conditions was calculated for a period of 5 years. Results The newly developed veneering ceramic Eris® showed a higher fracture strength (σ0 = 66.1 MPa) at a failure probability of PF = 63.2%, and crack growth parameters (n = 12.9) compared to the veneering ceramic Empress® 2 (σ0 = 60.3 MPa). For Empress® 2 veneer the crack propagation parameter n could only be estimated (n = 9.5). This is reflected in the prognosis of long-term resistance presented in the SPT diagrams. For all materials investigated, the Weibull parameter m values (Empress® 2 framework m = 4.6; Empress® 2 veneer m = 7.9; Eris® m = 6.9) were much lower than the minimum demanded by the literature (m = 15). Significance The initial fracture strength value alone is not sufficient to characterize the mechanical resistance of ceramic materials, since their stressability is time-dependent. Knowledge about the crack propagation parameters n and A are of great importance when preclinically predicting the clinical suitability of dental ceramic materials. The use of SPT diagrams for lifetime calculation of ceramic materials is a valuable method for comparing different ceramics.

A multi-centre randomized clinical trial is under way at 14 university dental schools in Germany to compare prosthodontic treatments for the shortened dental arch (SDA). One of the aims of this pilot-study was to measure the effect of two treatment options of the SDA on oral health-related quality of life and on the Research Diagnostic Criteria (RDC) for temporomandibular disorders (TMD). Thirty-four patients participated in the pilot-study. Inclusion criteria were: all molars were missing and the presence of at least both canines and one premolar in each quadrant. Participants were randomly assigned to receive either removable partial dentures including molar replacement (RPD_group) or retain a premolar occlusion (PROC_group). The Oral Health Impact Profile (OHIP-49) and the RDC for TMD were completed by participants before treatment (pre-treatment), 6 weeks (6 wks), 6 months (6m) and 12 months (12 m) after treatment. At the 12-month follow up, data of 10 women and 11 men (mean age: 62 +/- 10 years) were available. Medians of the OHIP total-scores were as follows: RPD (n = 10), 43.5 (pre-treatment), 18.2 (6 wks), 13.3 (6m), 14.7 (12 m). PROC (n = 11): 31.8 (pre-treatment), 27.1 (6 wks), 8.8 (6m), 8.3 (12 m). Significant differences were shown for RPD_group between pre-treatment and 6m/12 m and for PROC_group between pre-treatment and 6m. There were no significant differences between treatment groups at any time. Within each group, an improvement of life-quality was observed. No significant difference could be reported between the two therapy concepts. This may be due to the low sample size within the pilot study.

The aim of this multi-center, randomized controlled trial was to assess the impact of missing posterior support on the risk for temporomandibular disorder (TMD) pain by comparing patients with either shortened dental arches (SDA) or molar replacement by removable dental prostheses (RDP). A sample of 215 patients with bilateral molar loss in at least one jaw was consecutively recruited in 14 prosthodontic departments of dental schools in Germany. Of the initial sample, 152 patients (mean age: 59.7 years; 53.9 % female) received randomly allocated interventions (SDA: n = 71; RDP: n = 81). Presence of TMD pain was assessed using patients’ self-reports and was verified by physical examination and by pain intensity, as the mean of current pain, worst pain, and average pain in the last 6 months, with 10-point ordinal rating scales. Assessments were performed before treatment and at follow-ups until 60 months after treatment. Impact of interventions on TMD risk and pain intensity was computed by applying logistic and linear random-intercept models. Tooth replacement (RDP) did not significantly change the risk for self-reported (odds ratio [OR]: 1.1; confidence interval [CI]: 0.4 to 3.4) or clinically verified (OR: 0.7; CI: 0.1 to 4.3) TMD pain compared to no tooth replacement (SDA). Mean characteristic pain intensity was virtually identical in both groups (Coeff: 0.01; CI: −0.30 to 0.32). Retaining or preservation of an SDA is not a major risk factor for TMD pain over the course of 5 years when compared to molar replacement with RPDs. Seemingly, missing molars do not have to be replaced in order to prevent TMD pain.

PURPOSE The aim of this study was to evaluate the fracture resistance and fracture behavior of monolithic zirconia crowns in accordance with the preparation design and aging simulation method. MATERIALS AND METHODS An upper first molar was prepared sequentially with three different preparation designs: shoulderless preparation, 0.4 mm chamfer and 0.8 mm chamfer preparation. For each preparation design, 30 monolithic zirconia crowns were fabricated. After cementation on Cr-Co alloy dies, the following artificial aging procedures were performed: (1) thermal cycling and mechanical loading (TCML): 5000 cycles of thermal cycling 5℃–55℃ and chewing simulation (1,200,000 cycles, 50 N); (2) Low Temperature Degradation simulation (LTD): autoclave treatment at 137℃, 2 bar for 3 hours and chewing simulation; and (3) no pre-treatment (control group). After artificial aging, the crowns were loaded until fracture. RESULTS The mean values of fracture resistance varied between 3414 N (LTD; 0.8 mm chamfer preparation) and 5712 N (control group; shoulderless preparation). Two-way ANOVA analysis showed a significantly higher fracture loads for the shoulderless preparation, whereas no difference was found between the chamfer preparations. In contrast to TCML, after LTD simulation the fracture strength of monolithic zirconia crowns decreased significantly. CONCLUSION The monolithic crowns tested in this study showed generally high fracture load values. Preparation design and LTD simulation had a significant influence on the fracture strength of monolithic zirconia crowns.

To investigate nursing home managers' perceptions and attitudes towards oral health care and access to dental services for aged care facility residents.Questionnaires containing 28 closed-ended questions were mailed to all 114 nursing homes in Saarland, Germany. Descriptive statistics were calculated for response items.Facility response rate was 39%. None of the nursing homes in this study offered systematic dental health care. Initial dental screening was carried out only in one facility. In 81%, dental examinations only took place if required. Although stationary dental equipment was available only in one home, dental treatment was carried out in 71% of the cases by a dentist in the nursing home. Eighty-four per cent of the homes' managements rated the state of the dentition of the inhabitants as satisfying. Over half of the managers indicated satisfaction with the know-how of their nursing staff concerning oral hygiene procedures. The most significant barriers to provision of dental care in the facilities according to their managers were staff shortage, lack of interest of the inhabitants and financial concerns.The results of this study showed an urgent need for estimating a programme for systematic dental care for institutionalised elder people in the federal state of Saarland.

The objective of this in vitro study was to investigate the behavior of different composite restorative materials under the load of cast circumferential clasps for removable dental prostheses (RDPs). In 60 human molars, standardized mesial–occlusal–distal cavities were prepared. The cavities were restored with the following materials: Definite, Tetric Ceram, SureFil, Heliomolar RO, Ariston pHc, and Oralloy, and provided with a rest seat. The rest seats were subjected to 5,000 cycles of thermal cycling and 1,200,000 masticatory cycles in a mastication simulator via cobalt–chromium circumferential clasps cast to standardized frameworks in a laboratory model designed to simulate the biomechanics of a free-end denture base. Fracture analysis of the restorations was performed by light microscopy. Before and after loading, material wear was measured with a 3D-laser scanner, and an analysis of the marginal quality was performed in an SEM at ×200 applying the replica technique. No significant differences in the fracture behavior among the composite materials were found; the amalgam control group showed a significantly higher fracture resistance. Regarding the wear of the materials, the composites Definite and SureFil exhibited a behavior similar to that of amalgam. The other composites demonstrated higher wear rates. The initial marginal quality was significantly worse for Ariston pHc. The marginal adaptation decreased significantly after thermal and mechanical loading for Definite and Ariston pHc. In terms of the investigated aspects of mechanical performance, the tested composites seemed to be inferior to amalgam. Further clinical studies are needed to evaluate the ability of composite restorations to provide support for RDP clasps. The use of composites as direct restoration materials should be avoided in teeth, which serve as abutments for clasp-retained RDPs.

MorphoDent, a computer-assisted learning program designed to teach the anatomy of the adult dentition, was introduced into the curriculum of dentistry at the University of Saarland in Homburg, Germany. Thirty-six second-year students of the School of Dentistry were introduced to morphoDent alongside the traditional lectures of dental anatomy. Questionnaires that evaluated the students’ perceptions of virtual learning as well as aspects of the functionality of the program educational objectives were developed and distributed to the students. Online tests were performed and compared with a traditional examination. All questionnaires were returned. A wide variety of aspects dealing the pedagogic implications of e-learning were evaluated by the students, with the overall result being that students are aware of the needed hardware and technical skills and expect the quality of their studies to improve by implementation of e-learning. All sophomores except one felt that morphoDent had helped them in learning dental morphology and reported enjoying the virtual anatomical examination. One-third reported technical difficulties in operating the program. The average exam score was 2.53 (SD: 0.66) for the traditional and 2.23 (SD: 0.59) for the online dental anatomy test. Students expressed their positive attitude towards e-learning in general and indicated that the use of photorealistic 3D models of human teeth supported the process of individual learning of dental anatomy. The online test could be rated as a good option for students’ self-performance rating.

The evidence concerning the management of shortened dental arch (SDA) cases is sparse. This multi-center study was aimed at generating data on outcomes and survival rates for two common treatments, removable dental prostheses (RDP) for molar replacement or no replacement (SDA). The hypothesis was that the treatments lead to different incidences of tooth loss. We included 215 patients with complete molar loss in one jaw. Molars were either replaced by RDP or not replaced, according to the SDA concept. First tooth loss after treatment was the primary outcome measure. This event occurred in 13 patients in the RDP group and nine patients in the SDA group. The respective Kaplan-Meier survival rates at 38 months were 0.83 (95% CI: 0.74-0.91) in the RDP group and 0.86 (95% CI: 0.78-0.95) in the SDA group, the difference being non-significant.

AIM In the present study, prefabricated abutments made of zirconium dioxide Y-TZP (tetragonal zirconia polycrystals) were inserted into the posterior region under controlled clinical conditions. The aim was to test whether abutments made of zirconium dioxide are suitable for this indication. Investigation parameters included reactions of peri-implant tissue and the structural integrity of the all-ceramic superstructures on the implants. Results after 12 months in function are reported in this article. MATERIAL AND METHODS Forty implants of the XiVE S plus screw-type implants (DENTSPLY Friadent) were inserted into the posterior region of 24 patients. After the healing period, the implants were provided with all-ceramic abutments made of zirconium dioxide Y-TZP (FRIADENT CERCON Abutment; DENTSPLY Friadent). All-ceramic crowns (CERCON smart ceramics; DENTSPLY DeguDent) were used as superstructures and cemented using the conventional method. The following parameters were used to document the state of soft tissue: modified plaque index (mPI), sulcus fluid flow rate (SFFR, Periotron; Oraflow Inc), modified sulcus bleeding index (mSBI) and pocket depth (ST). Mesial and distal bone levels were determined on radiographs during the prosthetic treatment and at the 12-month recall. The Periotest (Medizintechnik Gulden) was used to determine implant stability. RESULTS All implants could be followed up after 12 months in function. In the presence of good oral hygiene (mPI: 0.5), the parameters SFFR (18) and mSBI (0.5) were indicative of stable and healthy soft tissue. ST was highest at the distal points of measurement (2.3 mm) and was generally at a low level. Compared with the baseline situation, proximal bone defects were reduced from -1.1 to -1 mm during the 12-month period of functioning. The mean Periost values at the 12-month recall were -1.9 in the maxilla and -3.8 in the mandible. Neither implant loss nor crown fractures occurred. Chipping of parts of the veneering ceramic was registered in four cases (10%). CONCLUSION After 12 months of wear, no mechanical failure was registered in any of the all-ceramic abutments. On clinical investigation, the peri-implant hard and soft tissues were largely healthy and devoid of inflammation.

Background Various treatment options for the prosthetic treatment of jaws where all molars are lost are under discussion. Besides the placement of implants, two main treatment types can be distinguished: replacement of the missing molars with removable dental prostheses and non-replacement of the molars, i.e. preservation of the shortened dental arch. Evidence is lacking regarding the long-term outcome and the clinical performance of these approaches. High treatment costs and the long time required for the treatment impede respective clinical trials. Methods/design This 14-center randomized controlled investigator-initiated trial is ongoing. Last patient out will be in 2010. Patients over 35 years of age with all molars missing in one jaw and with at least both canines and one premolar left on each side were eligible. One group received a treatment with removable dental prostheses for molar replacement (treatment A). The other group received a treatment limited to the replacement of all missing anterior and premolar teeth using fixed bridges (treatment B). A pilot trial with 32 patients was carried out. Two hundred and fifteen patients were enrolled in the main trial where 109 patients were randomized for treatment A and 106 for treatment B. The primary outcome measure is further tooth loss during the 5-year follow-up. The secondary outcome measures encompassed clinical, technical and subjective variables. The study is funded by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG WA 831/2-1, 2-2, 2-3, 2-4, 2-5). Discussion The particular value of this trial is the adaptation of common design components to the very specific features of complex dental prosthetic treatments. The pilot trial proved to be indispensable because it led to a number of adjustments in the study protocol that considerably improved the practicability. The expected results are of high clinical relevance and will show the efficacy of two common treatment approaches in terms of oral health. An array of secondary outcome measures will deliver valuable supplementary information. If the results can be implemented in the clinical practice, the daily dental care should strongly profit thereof. Trial registration The trial is registered at ClinicalTrials.gov under ISRCTN68590603 (pilot trial) and ISRCTN97265367 (main trial).

Prefabricated implant abutments made of zirconium dioxide (yttria-stabilized polycrystalline tetragonal zirconia; Y-TZP) have proved to be useful in the esthetically demanding anterior region and may also be useful for premolar and molar replacement because of their obvious positive impact on the health of peri-implant soft tissues.Forty screw implants were inserted in the posterior region of 24 patients and provided with prefabricated all-ceramic abutments made of zirconium dioxide Y-TZP. Zirconia-based crowns were used as superstructures. The following parameters were used to document the state of soft tissue: the modified plaque index (mPI), sulcus fluid flow rate (SFFR), modified sulcus bleeding index (mSBI), and probing depth (PD). Additionally, implant stability was measured using an electronic mobility testing device.All implants (N = 40) followed up after 6 months in function were osseointegrated and showed good stability. In the presence of good oral hygiene (mPI: 0.3), the parameters SFFR (16) and mSBI (0.7) were indicative of stable and healthy soft tissue. The mean PD was highest at the distal points of measurement (2.4 mm) and was generally at a low level. Neither implant loss nor crown fractures occurred. Chipping of parts of the veneering ceramic was registered in three cases (7.5%).After 6 months in function, no mechanical failure was registered in any of the all-ceramic abutments. On clinical investigation, the peri-implant soft tissues were largely healthy and devoid of inflammation.

This in vitro study investigated the fracture behaviour of implant–implant-supported and implant–tooth-supported all-ceramic fixed dental prostheses (FDP) using zirconium dioxide implant abutments (FRIADENT® CERCON® abutments, DENTSPLY Friadent). Six different test groups (n = 8) were prepared. Groups 1, 2, 4, and 5 represented an implant–implant-supported FDP condition, whereas groups 3 and 6 simulated an implant–tooth-supported FDP condition. The second right premolar of the mandible was replaced with a pontic tooth. In groups 2 and 5, implant abutments were individualised by circumferential preparation. XiVe® S plus screw implants (DENTSPLY Friadent) that were 4.5 mm (first molar) and 3.8 mm (first premolar) in diameter and 11 mm in length and metal tooth analogues with simulated periodontal mobility, representing the first right premolar, were mounted in a polymethyl methacrylate block. The FDPs were cemented with KetacCem (3 M Espe GmbH, Germany). Groups 4, 5, and 6 were thermomechanically loaded (thermal and mechanical cycling (TCML) = 1.2 × 106; 10,000 × 5°/55°) and subjected to static loading until failure. Statistical analysis of data obtained for the force at fracture was performed using non-parametric tests. All samples tested survived TCML. In the implant–implant-supported groups, circumferential abutment preparation resulted in a tendency to lower fracture forces compared to groups with unprepared abutments (group 1, 472.75 ± 24.71 N; group 2, 423.75 ± 48.48 N; group 4, 647.13 ± 39.10 N; group 5, 555.86 ± 30.34 N). The implant–tooth-supported restorations exhibited higher fracture loads (group 3, 736.25 ± 82.23 N; group 6, 720.75 ± 48.99 N) than the implant–implant-supported restorations which did not possess circumferentially individualised abutments. Statistically significant differences were found when comparing the non-artificially aged groups. Implant–tooth-supported FDP restorations did exhibit an increased fracture load compared to implant–implant-supported FDP restorations.

The aim of the study was to evaluate the influence of artificial aging on the fracture behavior of straight and angulated zirconia implant abutments (ZirDesign™; Astra Tech, Molndal, Sweden) supporting anterior single crowns (SCs). Four different test groups (n = 8) representing anterior SCs were prepared. Groups 1 and 2 simulated a clinical situation with an ideal implant position (left central incisor) from a prosthetic point of view, which allows for the use of a straight, prefabricated zirconia abutment. Groups 3 and 4 simulated a situation with a compromised implant position, requiring an angulated (20°) abutment. OsseoSpeed™ implants (Astra Tech) 4.5 mm in diameter and 13 mm in length were used to support the abutments. The SCs (chromium cobalt alloy) were cemented with glass ionomer cement. Groups 2 and 4 were thermomechanically loaded (TCML = 1.2 × 106; 10,000 × 5°/55°) and subjected to static loading until failure. Statistical analysis of force data at the fracture site was performed using nonparametric tests. All samples tested survived TCML. Artificial aging did not lead to a significant decrease in load-bearing capacity in either the groups with straight abutments or the groups with angulated abutments. The restorations that utilized angulated abutments exhibited higher fracture loads than the restorations with straight abutments (group 1, 280.25 ± 30.45 N; group 2, 268.88 ± 38.00 N; group 3, 355.00 ± 24.71 N; group 4, 320.71 ± 78.08 N). This difference in load-bearing performance between straight and angulated abutments was statistically significant (p = 0.000) only when no artificial aging was employed. The vast majority of the abutments fractured below the implant shoulder.

Statement of problem Adhesive resin cements are commonly used to lute all-ceramic posts despite limited scientific data on the clinical effectiveness of using bonding agents within prepared root canals. Purpose The purpose of this study was to retrospectively evaluate the clinical performance of conventionally cemented zirconia posts. Loss of retention, fracture of posts, and fracture of teeth were evaluated. Material and methods Thirty pulpless teeth in 22 patients were treated with zirconia posts. With the exception of 3 situations in which posts were inserted directly and the access openings were closed with composite resin, teeth were restored with indirectly fabricated post-and-core foundations made from zirconia posts (Cerapost or Cosmopost) combined with heat-pressed ceramic cores (IPS Empress Cosmo) and ceramic crowns (IPS Empress II). Restorations (posts and crowns) were cemented with glass-ionomer cement (KetacCem) or resin-modified glass-ionomer cement (ProTec Cem) and reevaluated, retrospectively, for failures such as loss of retention or fractures. Data were reported using descriptive statistics. Results The mean observation period was 29 months (range 8-44 months). No loss of retention or fracture of any restoration was observed. Conclusion Although this study involved a relatively short observation period, there were no signs of failure of conventionally cemented zirconia posts with ceramic crowns.

Despite the wide variety of all-ceramic systems available today, the majority of dental practitioners hesitate to recommend and insert all-ceramic crowns. This article regards the nature of the ceramic materials, the principles of bonding and adhesion, and the clinical problems of the acid-etch technique for crowns. Advantages and disadvantages are discussed, and the influences of different factors on the strength of all-ceramic crowns are presented. Finally, the conclusion is drawn that conventional cementing of all-ceramic crowns is possible when the specific properties of the ceramics are taken into consideration.