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Objectives: To investigate the survival rates and fracture resistance of dentures made from different teeth (milled, 3D-printed, fabricated), bases (milled, 3D-printed, pressed) and bonding combinations., Materials and Methods: Specimens (11 groups, n = 8 per group) were fabricated from combinations with a denture tooth (anterior tooth 21) and a denture base material. The groups consisted of combinations of teeth (6x), denture base materials (5x) and adhesive bonding options (4x). The teeth were printed, milled or prefabricated. The denture base was produced conventionally or was milled or 3D-printed. Two dentures were milled from one industrially produced block. The dentures were subjected to thermal and mechanical loading (TCML) and subsequent fracture test., Statistics: ANOVA, Bonferroni-test, Kaplan-Meier survival, Pearson correlation; α = 0.05., Results: Mean loading cycles varied between 221,869 (8), 367,610 (11), 513,616 (6) 875,371 (3) and 9,000,030 (4). ANOVA revealed significant (p ≤ 0.001) different surviving cycles. Log Rank test showed significantly (p < 0.001) different loading cycles. Fracture force after TCML varied between 129.8 +/- 97.1 N (3) and 780.8 +/- 62.5 N (9). ANOVA comparison revealed significant (p < 0.001) different fracture loadings between the individual systems. Correlation was found between fracture force and loading cycles (0.587, p < 0.001)., Conclusions: Different survival rates and fracture forces were found for dentures made of different teeth (milled, 3D-printed, prefabricated), bases (milled, 3D-printed, pressed) and bonding combinations. Milled, pressed and prefabricated systems provided longer survival and fracture force than the other tested systems., Clinical Relevance:  Optimal tooth-base combinations can help to produce a denture that is stable and resistant during clinical application., Competing Interests: Declarations. Ethical approval: Not Applicable. Informed consent: Not Applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Objectives: This study investigated the influence of prophylactic treatments and thermocycling on the marginal and internal veneering interface (tooth-veneer) as well as on the surface texture of ceramic veneers., Materials and Methods: A total of 32 extracted human premolars were restored with veneers made of lithium disilicate (LDS) or zirconia-reinforced lithium silicate (ZLS). An artificial aging of the specimens was conducted via five cycles of both thermocycling (5/55°C) and prophylactic treatment (powder air polishing or ultrasonic scaling). Changes in the marginal interface and in the surface texture were examined using confocal laser scanning microscopy. The internal interface and the microstructure were investigated using micro X-ray computed tomography., Results: Artificial aging resulted in a deepening of the marginal interface across all groups (mean height: 4.51-15.74 μm, maximum height: 10.42-22.71 μm, cross-section: 256.68-1525.84 μm², regardless of the veneer material or prophylaxis method. No change in surface texture was observed. The internal interface exhibited defects for all groups after artificial aging. ZLS showed cracks in five out of eight veneers after exposure to ultrasonic scaling and thermocycling., Conclusion: Ceramic veneers exhibited a high resistance to prophylactic measures in terms of surface durability, but a deepening of the marginal interface should be taken into account. With regard to the formation of cracks within the material, the use of ultrasonic scaling is not recommended for ZLS veneers., Clinical Relevance: The influence of artificial aging, including prophylactic treatments, plays a critical role in assessing longevity for veneers in defect-oriented and esthetic dentistry., Competing Interests: Declarations. Ethical approval: This study was approved by the institutional Ethics Committee at the Medical Faculty of the Leipzig University (286/18-ek). Informed consent: Not Applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Objectives: To evaluate three temporary luting cements in terms of their restoration loss rates, biological interactions, esthetic properties, and handling characteristics., Materials and Methods: 75 adults requiring fixed prosthodontics voluntarily participated in a single-blind, randomized controlled trial. After preparation, temporary restorations were luted with a randomly selected temporary luting cement (either Provicol QM Plus (PQP), Bifix Temp (BT), or Provicol QM Aesthetic (PQA)). Clinical examinations were performed one to two weeks after cementation. The following criteria were evaluated: tooth vitality, percussion, hypersensitivity, gingival bleeding, odor formation, esthetics, cement handling, removability, cleanability, and retention loss. Antagonistic teeth served as controls. Statistical analysis was performed using the paired t-test, one-way ANOVA, Pearson's chi-square and Fisher's exact test, where appropriate., Results: The overall loss rate of temporary restorations was 16.0%, showing no cement-specific differences. Postoperative hypersensitivity occurred in 8% of cases regardless of cement type. Esthetic impairment was reported by 31% of the PQP-fixed restorations, compared with 4.0% and 4.2% of the BT and PQA-bonded restorations. Cement application was reported to be easy in 100% of cases, excess removal in 88-96%, depending on the cement used., Conclusions: The choice of luting material affects the esthetic appearance of a temporary restoration and should be considered, particularly in restorations in esthetically demanding areas. No significant differences between the cements were identified regarding biocompatibility, handling, and loss rate., Clinical Relevance: Translucent cements can help to reduce color interferences, resulting in a more appealing appearance of the temporary restoration., (© 2024. The Author(s).)

Objectives: To investigate the clinical performance of chairside fabricated tooth-supported posterior single crowns from lithium disilicate ceramic., Materials and Methods: Thirty-four crowns (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein) were inserted between 2006 and 2007 and again evaluated after 15 years. Survival and success rates were calculated according to Kaplan-Meier, and the quality of the crowns was evaluated by using modified United States Public Health (USPHS) criteria., Results: Twenty-two crowns were available for recall; six patients were defined as dropouts. The mean observation period was 15.2 years (± 0.2). Six failures occurred (1 technical/5 biological) resulting in a survival rate of 80.1%. The success rate was 64.2%. The roughness of the crowns increased (p = 0.021) and the majority of adhesive gaps were discolored (p = 0.001) in comparison to baseline. The color, tooth, and crown integrity remained stable over the follow-up period (p ≥ 0.317)., Conclusion: The fabrication of tooth-supported lithium disilicate crowns using a chairside approach yielded acceptable long-term survival and success rates. Due to discoloration, the long-term use of dual-cure self-adhesive resin cements might result in unpleasing esthetic results., Clinical Relevance: The performance of posterior lithium disilicate single crowns revealed excellent to good clinical quality and an acceptable number of events after 15 years of clinical service., (© 2023. The Author(s).)

Objectives: The aim of this study was to investigate the influence of dental prophylaxis cleaning procedures and artificial aging on veneers in human teeth. The external marginal and internal tooth veneer as well as the restoration surfaces were examined., Material and Methods: Thirty-two extracted premolars were restored with resin-based composite (RBC) and polymer-infiltrated ceramic network (PICN) veneers. Artificial aging by alternating thermocycling and subsequent prophylaxis procedure (glycine-based powder air polishing or ultrasonic scaling) was conducted for five consecutive cycles. The external marginal interface was examined by height profile measurements and the internal interface was investigated using micro X-ray computed tomography. In addition, the surface texture of the veneer surface was analyzed using confocal laser scanning microscopy., Results: The application of both prophylaxis procedures resulted in a deepening of the marginal interface (10 µm ± 8 µm) for materials. Furthermore, the internal interface of PICN restorations showed marginal gaps after both treatments and artificial aging (16 µm ± 3 µm). In contrast to the RBC specimens, a significant increase in surface roughness was identified for PICN veneers after ultrasonic scaling., Conclusions: The marginal and internal interface regions in veneers fabricated from PICN and RBC were affected by prophylaxis procedures. Furthermore, it may result in increased veneer surface roughness, especially in PICN and after ultrasonic scaling, which might affect bioadhesion and longevity., Clinical Relevance: After dental prophylaxis procedures, examination of the marginal and the internal interface as well as the veneer surface provides a precise insight into damage mechanisms and offers an assessment of longevity., (© 2022. The Author(s).)

Objectives: The objective was to describe the physical and psychosocial features of patients attending a specialized consultation hour for temporomandibular disorders (TMD). This investigation focused on those patients who did not receive a diagnosis according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)., Materials and Methods: From 2004 to 2017, patients seeking care during a TMD-specialized consultation hour were consecutively recruited. Each patient completed a TMD-related questionnaire, psychosocial questionnaires (Graded Chronic Pain Scale, Hospital Anxiety and Depression Scale, Beschwerden-Liste), and the Oral Health Impact Profile-49. The clinical examination was performed according to the RDC/TMD., Results: The mean age of the 1020 patients was 43.3 years (75.3% female). According to the RDC/TMD decision trees, 351 patients were categorized without a TMD diagnosis (NoTMDdx). The most frequent reasons for seeking care were orofacial pain/TMJ pain or headaches revealing an OR of 1.89 (for TMDdx group). A relevant proportion of patients was categorized as positive for anxiety (NoTMDdx/TMDdx 30.8/41.2%; p = 0.072), depression (20.8/23.9%; p = 0.433), non-specific physical symptoms (31.4/44.1%; p < 0.001), or dysfunctional chronic pain (11.5/18.2%; p < 0.001). In both patient groups, the oral health-related quality of life was impaired (42.9/52.7 points; p < 0.001), and the frequency of therapy measures prior to the consultation hour was high., Conclusions: Patients seeking care from TMD specialists were usually referred with TMD-associated symptoms. Of those, a relevant proportion did not receive a diagnosis according to RDC/TMD decision trees., Clinical Relevance: Psychosocial screening and the avoidance of overtreatment are recommended for patients with TMD-related symptoms., (© 2021. The Author(s).)

Objectives: This study aimed to survey dentists in Germany to identify their favored materials for the fabrication of tooth-supported single crowns (SCs) depending on the location of the abutment teeth and the preparation margin., Materials and Methods: The survey included questions regarding demographic characteristics of dentists/their dental practice and preferred restorative materials for the fabrication of SCs for abutment teeth 16, 11, 34, and 36 with either supra- or subgingival preparation margins., Results: Between August 2019 and February 2020, 721 dentists participated in the survey; responses from 33 dentists were excluded from data analysis because the dentists did not work in Germany or provided less than one fixed dental prosthesis/month. Dentists favored ceramic materials independent of the location of the abutment tooth and preparation margin (56.6-92.2%). CAD/CAM resin composites or full metals were preferred by only a few participants. A significantly higher proportion of dentists recommended porcelain fused to metal for subgingival preparation margins than for supragingival margins (p < 0.001). Characteristics of dentists/dental practices influenced a single scenario (11 subgingival) that was dependent on the dentist's time since graduation. When asked to specify the ceramic materials, numerous participants wrote a free response (5.7-7.8%) or did not answer (0.7-4.8%)., Conclusions: Dentists in Germany selected restorative materials for SCs depending on the clinical scenario. Since numerous dentists did not specify the ceramic materials, postgraduate information and education might help to extend expertise., Clinical Relevance: The results of this survey provide insight into the favored materials of dentists for the fabrication of tooth-supported SCs.

Objectives: Definition of implant success is unclear in prosthetic implant-based rehabilitation of head neck cancer patients., Materials and Methods: Fifty-two patients with 309 inserted implants were included in this prospective observational study. Implant survival (in situ and loaded) and implant success (modified Albrektsson criteria) at 2-year follow-up were evaluated under the influence of patient- and implant-specific variables., Results: Thirty-nine patients with 234 implants finished the study. Overall implant survival after 2 years was 92.3% (216/234) with an osseointegration rate of 94% (220/234). Implant success was 78.6% (184/234). Main reasons for failure were "bone resorption > 1.7mm" (n = 27, 11.5%) and "implant not in situ or not loaded" (n = 18, 7.7%). Smoking (OR 3.1, p = 0.034), bone grafts (OR 2.4, p = 0.021) and radiation dose > 60 Gy (OR 3.8, p = 0.025) revealed as significant predictors for implant failure., Conclusion: Implant survival differs significantly from implant success in head and neck cancer patients. Implant success is mainly determined by radiographic peri-implant bone resorption., Clinical Relevance: Dealing with head and neck cancer patients a higher amount of peri-implant bone resorption must be taken into account and warrants for intensified implant monitoring.

Objectives: The aim of this study was to analyse the impact of different clinical conditioning approaches and an ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based experimental primer for intraoral luting of buccal tubes on silica-based ceramic surfaces., Materials and Methods: A total of 60 leucite-reinforced glass ceramic molar crowns were conditioned using different methods (n = 10): I-roughening, hydrofluoric acid, silane; II-roughening, silane; III-roughening, experimental coupling agent; IV-experimental coupling agent; V-roughening; VI-no treatment. A buccal tube was adhesively luted to the ceramic surface. Subsequently, water storage, thermocycling and chewing simulation were carried out. The shear bond strength (SBS) was determined, and changes in the surface were assessed., Results: All tubes of the control group (group VI) debonded after incubation. The conditioning methods using coupling agents revealed mean values for SBS of 61.56 MPa (group I), 45.53 MPa (group III), 41.65 MPa (group II), and 23.14 MPa (group IV). In groups I-III, both composite residues and cracks/tear-outs were detected., Conclusions: The conditioning of silicate ceramic surfaces with a suitable coupling agent system appears to allow sufficient adhesive luting of buccal tubes. The intraoral luting of fixed appliance elements on silicate ceramic surfaces using an ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based ceramic primer can withstand orthodontic forces., Clinical Relevance: Ammonium polyfluoride- and trimethoxysilylpropyl methacrylate-based ceramic primers revealed promising results for the intraoral adhesive luting of orthodontic devices to silica-based ceramic crowns.

Objectives: The aim of this study was to investigate the attitude, observations, and knowledge of German dentists regarding the management of dry mouth., Materials and Methods: A questionnaire including queries about attitudes, observations, and treatment options in patients with dry mouth was developed and sent to all 1251 dentist members of a regional German dental association., Results: An overall total of 284 returned questionnaires were included in the analyses, which relates to a response rate of 22.7%. Dentists infrequently encountered dry mouth in their clinical routine, yet were well aware that patients suffer from the symptoms of dry mouth; for affected patients, the majority of participating dentists provided specific dental prophylaxis measures. Drug side effects, neoplasia, and psychological disorders were regarded as the primary etiological factors for dry mouth, and caries, increased plaque formation, and rhagades as the most frequently observed clinical symptoms. While the majority of participating dentists was of the opinion that saliva substitutes are useful treatment options in patients with dry mouth, only few frequently recommended their use. Mechanical and gustatory stimulation of salivary flow as well as the advice to rinse with water were the most frequently pursued treatment options., Conclusions: Despite the high prevalence of dry mouth identified in epidemiological studies, it appears to be an infrequent observation in clinical routine., Clinical Relevance: Pre- and postgraduate education should sensitize dentists for dry mouth and its treatment options.

Objectives: To investigate the surface roughness of CAD/CAM materials immediately after milling and after different chairside and labside polishing procedures. A two-body wear test was performed to compare the different wear characteristics of the materials and the corresponding antagonists., Materials and Methods: Specimens (n = 12 per series) from different CAD/CAM materials (three composites: Lava Ultimate, Cerasmart, BRILLIANT Crios; one hybrid ceramic: VITA Enamic; three ceramics: Celtra Duo, VITA Suprinity, IPS Emax.CAD) were polished according to the manufacturer's instructions. The effect of different polishing procedures was investigated by comparing surface roughness (R a , R max ) after labside polishing and after chairside polishing. Wear behavior (mean, volume, and maximum wear) of specimens and antagonists as well as changes in surface roughness were determined in a pin-on-block wear test. Statistical analysis was performed with a one-way analysis of variance (ANOVA)/Bonferroni multiple-comparison post hoc test and a multifactorial ANOVA/Tukey's significant difference post hoc test (α = 0.05). SEM micrographs were used for the qualitative evaluation of surfaces and wear traces., Results: After chairside high-gloss polishing, ceramics and composites exhibited R a values between 0.08 and 0.10 μm and between 0.11 and 0.13 μm, respectively. After labside high-gloss polishing, values varied between 0.02 and 0.09 μm for ceramics and between 0.06 and 0.16 μm for resin composites. No significant differences were found between labside and chairside pre- and high-gloss polishing. For the ceramics, lower mean wear depths (between - 132.2 ± 19.9 and - 137.0 ± 19.0 μm) were identified compared to the resin composites (which exhibited wear depths between - 159.1 ± 19.4 and - 176.3 ± 23.9 μm). For maximum wear depth and volume, a different ranking of the materials was found. Antagonistic wear varied between 12.0 ± 6.4% and 30.6 ± 9.9% and was higher for the ceramic materials and Lava Ultimate. For all materials, a smoothing between 0.20 and 2.70 μm (R a ) was identified after wear simulation., Conclusions: Chairside polishing is as effective as labside polishing, although surfaces were directly adjusted (roughened) only before the chairside polishing. Wear was lowest for ceramics, followed by the resin-infiltrated material and the resin composites., Clinical Relevance: Polishing after milling or adjustment is essential to guaranteeing optimal clinical performance. Chairside polishing after adjustment leads to comparably smooth surfaces as labside polishing after milling and grinding. Ceramics are expected to exhibit lower wear than resin composites under clinical conditions.

Objectives: The aim of this study was to investigate the in-vitro performance and fracture resistance of a temporary computer-aided designed and computer-aided manufactured polymethylmethacrylate (CAD/CAM-PMMA) material as implant or tooth-supported single crown with respect to the clinical procedure (permanently bonded/temporarily cemented)., Materials and Methods: Sixty-four crowns were fabricated on implants or human molar teeth simulating (a) labside procedure on prefabricated titanium-bonding base ([TiBase] implant crown bonded in laboratory, screwed chairside), (b) labside procedure ([LAB] standard abutment and implant crown bonded in laboratory, screwed chairside), (c) chairside procedure ([CHAIR] implant crown bonded to abutment), and (d) reference ([TOOTH] crowns luted on prepared human teeth). Crowns were made of a CAD/CAM-PMMA temporary material (TelioCAD, Ivoclar-Vivadent). For investigating the influence of fixation, half of the crowns were permanently (P) or temporarily (T) bonded. Combined thermal cycling and mechanical loading (TCML) was performed simulating a 5-year clinical situation. Fracture force was determined. Data were statistically analyzed (Kolmogorov-Smirnov test, one-way ANOVA; post hoc Bonferroni, α = 0.05)., Results: All restorations survived TCML without visible failures. Fracture results varied between 3034.3 (Tooth-P) and 1602.9 N (Tooth-T) [TOOTH], 1510.5 (TiBase-P) and 963.6 N (TiBase-T) [TiBase], 2691.1 (LAB-P) and 2064.5 N (LAB-T) [LAB], and 1609.4 (Chair-P) and 1253.0 N (Chair-T) [CHAIR]. Tested groups showed significantly (p < 0.001) different fracture values. Failure pattern was characterized by fractures in mesial-distal, buccal-oral, or mixed (mesial-distal/buccal-oral) directions, with differences for the individual groups., Conclusions: Temporary CAD/CAM crowns showed no different in-vitro performance but provided different fracture results that depended on cementation, screw channel, and type of abutment., Clinical Relevance: All bonded and screwed PMMA crowns were in a range where clinical application seems not restricted.

Objectives: The aim of this study is to investigate the performance and fracture resistance of different CAD/CAM ceramic and composite materials as implant- or tooth-supported single crowns with respect to the clinical procedure (screwed/bonded restoration)., Materials and Methods: One hundred twenty crowns were fabricated on implants or human molar teeth simulating (a) chairside procedure ([CHAIR] implant crown bonded to abutment), (b) labside procedure ([LAB] abutment and implant crown bonded in laboratory, screwed chairside), and (c) reference ([TOOTH] crowns luted on human teeth). Four materials were investigated: ZLS (zirconia-reinforced lithium silicate ceramic; Celtra Duo, Degudent: polished (P)/crystallized (C)), RB (resin-based composite; Cerasmart, GC), and RIC (resin-infiltrated ceramic; Enamic, Vita-Zahnfabrik). LiS (lithiumdisilicate; Emax CAD, Ivoclar-Vivadent) served as reference. Combined thermal cycling and mechanical loading (TCML) was performed simulating a 5-year clinical situation. Fracture force was determined. Data were statistically analyzed (Kolmogorov-Smirnov test, one-way ANOVA; post hoc Bonferroni, α = 0.05)., Results: One crown of ZLS&#95;C[LAB] (1,200,000 cycles) and RB[CHAIR] (890 cycles) failed during TCML. Fracture values varied between 977.7 N(RB) and 3070.4 N(LiS)[CHAIR], 1130.6 N(RB) and 2998.1 N(LiS)[LAB], and 1802.4 N(ZLS) and 2664.3 N(LiS)[TOOTH]. Significantly (p < 0.003) different forces were found between the materials in all three groups. ZLS&#95;C, RIC, and RB showed significantly (p < 0.014) different values for the individual groups., Conclusions: Partly ceramic and resin-based materials performed differently on implant or tooth abutments. The insertion of a screw channel reduced the stability for individual crown materials. Insertion of the screw channel should be performed carefully., Clinical Relevance: All restorations were in a range where clinical application seems not restricted, but insertion of a screw channel might reduce stability of individual materials.

Objectives: This in vitro study evaluated the marginal quality of Lava Ultimate inlays in deep proximal cavities with and without proximal box elevation (PBE) before and after thermomechanical loading (TML)., Materials and Methods: Mesio-occluso-distal cavities with proximal boxes beneath the cementoenamel junction (CEJ) were prepared in 24 human molars. Then, one of the proximal boxes was elevated with Filtek Supreme above the CEJ. The specimens were divided into three groups (n = 8). The inlays of group A were adhesively luted to the cavities with Scotchbond Universal and Rely X Ultimate, the inlays of group B with Monobond Plus, Syntac, and Variolink II, and the inlays of group C with Clearfil Ceramic Primer and Panavia SA Cement. Epoxy resin replicas were taken before and after thermomechanical loading (1,200,000 cycles, 55 °C/5 °C, max. load 50 N). Marginal integrity at the different interfaces tooth/PBE, tooth/dentine, inlay/PBE, inlay/dentine was evaluated with scanning electron microscopy (×200). The percentage of continuous margin (% of total proximal margin length) was compared between the groups before and after TML., Statistics: Mann-Whitney U test (p = 0.05)., Results: No significant differences (p > 0.05) before and after TML were found between the three groups for bonding the inlay to dentine or to PBE composite., Conclusions: The marginal integrities of bonding inlays directly to dentine are not different from bonding inlays to a proximal box, which has been elevated by a composite filling material. For deep proximal cavities, the PBE technique could be an alternative technique to conventional methods. Clinical research is needed to confirm.

Objectives: Flowable bulk-fill resin bonded composites (RBCs) are supposed to show improved abrasion resistance and fracture toughness in comparison to flowable conventional RBCs., Materials and Methods: Specimens of eight flowable RBCs (5× flowable conventional, 3× flowable bulk-fill) were fabricated for testing relative fracture toughness (SENB), relative three-body wear, the Vickers hardness, glass transition Tg (differential scanning calorimetry; DSC) and filler mass fraction (thermal gravimetric analysis; TGA). A laboratory veneering composite was used as a reference. Fracture toughness and wear values were related to this reference. Scanning electron microscope images were evaluated for fraktographical and microstructural investigations. Statistical analyses were performed using one-way Anova, the Bonferroni post hoc test and the Pearson correlation test (α =0.05)., Results: Relative fracture toughness varied between 0.64 and 1.34 (1.00 = 1.69 MPam½) and relative wear rates between 1.24 and 0.55 (1.00 = 134 μm). The Vickers hardness ranged between 14.4 and 57.2 HV. TGA showed filler fractions between 55 and 77 wt.%. Tg values varied between -67.8 and -40.9 °C. None of the tests identified clear differences between flowable bulk-fills or conventional flowable RBCs. The Pearson correlation coefficient (cc) showed significant correlations (cc > 0.583; p < 0.001) between relative fracture toughness and hardness or filler content. There was a significant correlation (cc = 0.757; p = 0.005) between relative wear and glass transition temperature or between filler fraction and the Vickers hardness (cc > 0.702; p < 0.001). For all filler sizes breakdown was found, where clusters and pre-polymerized particles were partly disintegrated., Conclusions: Flowable bulk-fill RBCs showed no improved abrasion resistance and fracture toughness in comparison to flowable conventional RBCs., Clinical Relevance: Differences in the properties were higher between the individual materials than between the material groups. Therefore the appropriate material selection may be essential for a clinical success.

Objectives: Removable dentures with different denture teeth may provide different performance and resistance in implant and gingival situations, or anterior and posterior applications., Materials and Methods: Two situations of removable dentures were investigated: gingiva (flexible) and implant (rigid) bearing. For simulating the gingiva/jaw situation, the dentures were supported with flexible lining material. For the implant situation, implants (d = 4.1 mm) were screwed into polymethylenmethacrylate (PMMA) resin. Two commercial (Vita-Physiodens MRP, SR Vivodent/Orthotyp DCL) and two experimental materials (EXP1, EXP2) were investigated in anterior (A) and posterior (P) tooth locations. Chewing simulation was performed, and failures were analyzed (microscopy, SEM). Fracture strength of surviving dentures was determined., Results: Only EXP1 revealed failures during chewing simulation. Failures varied between anterior and posterior locations, and between implant (P:4x; A:7x) or gingiva (P:1x; A:2x) situations. Kaplan-Meier log-rank test revealed significant differences for implant situations (p < 0.002), but not for gingiva bearing (p > 0.093). Fracture testing in the implant situation provided significantly highest values for EXP2 (1476.4 ± 532.2 N) in posterior location, and for DCL (1575.4 ± 264.4 N) and EXP2 (1797.0 ± 604.2 N) in anterior location. For gingival bearing, significantly highest values were found for DCL/P (2148.3 ± 836.3 N), and significantly lowest results for EXP1/A (308.2 ± 115.6 N). For EXP1 + EXP2 + Vita/P and for EXP1/A no significant differences were found between implant- or gingiva-supported situations., Conclusions: Anterior and posterior teeth showed different material-dependent in vitro performance, further influenced by implant/gingiva bearing. While an implant in anterior application increased fracture strength of two materials, it decreased fracture values of 3/4 of the materials in posterior application., Clinical Relevance: Survival of denture teeth may be influenced by material, oral position, and bearing situation.

The aim of this in vitro study was to investigate the two-body wear of different ceramics. Two-body wear tests were performed in a chewing simulator with steatite and enamel antagonists, respectively. Specimens were loaded in a pin-on-block design with a vertical load of 50 N for 1.2 × 10(5) cycles; (f = 1.6 Hz; lateral movement, 1 mm; mouth opening: 2 mm). Human enamel was used as a reference. Three zirconia ceramics, three veneering porcelains, two glass-infiltrated and one lithium disilicate ceramic were investigated. Veneering and lithium disilicate ceramics were glazed before testing. Surface roughness Ra (SP6, Perthen-Feinprüf, G) and wear depth were determined using a 3D scanner (Laserscan 3D, Willytec, G). SEM (Quanta FEG 400, FEI, USA) pictures of the worn specimens and antagonists were made for evaluating wear performance. Veneering porcelain provided wear traces between 71.2 and 124.1 μm (enamel antagonist) and 117.4 and 274.1 μm (steatite). Wear of the steatite antagonists varied between 0.618 and 2.85 mm². No wear was found for zirconia and glass-infiltrated substructure ceramics. Also, no wear was found for the corresponding antagonists. Wear of specimens and antagonists was strongly material dependent. No visible wear was found on zirconia and glass-infiltrated ceramics. Porcelain and lithium disilicate ceramic showed a comparable or lower wear than the enamel reference. Antagonist wear was found to be lower when specimens were made of substructure oxide ceramics instead of veneering porcelain. From the point of wear testing, zirconia may be used for the fabrication of fixed dental prosthesis without veneering.

The aim of the present study was the quantification of Streptococcus mutans adhesion on ten widely used pit and fissure sealant materials and the correlation of these findings to surface roughness (R(a)) and surface free energy (SFE). Additionally, changes in streptococcal adhesion and surface parameters after water immersion and artificial aging have been investigated. Circular specimens of ten fissure sealants (seven resin-based composites, two glass ionomers, and one compomer) were made and polished. Surface roughness was determined by perthometer and SFE by goniometer measurements. Sealant materials were incubated with S. mutans suspension (2.5 h, 37 degrees C), and adhering bacteria were quantified by using a biofluorescence assay in combination with an automated plate reader. Surface properties and S. mutans adhesion were measured prior to and after water immersion after 1 and 6 months and after additional thermocycling (5,000 cycles; 5 degrees C/55 degrees C). The tested sealants showed significant differences in S. mutans adhesion prior to and after the applied aging procedures. Aging resulted in slight increases (mostly <0.2 microm) in surface roughness, as well as in significant decreases in SFE and in significantly lower quantities of adhering bacteria. Ketac Bond and UltraSeal XT plus revealed the lowest adhesion potential after artificial aging. In general, the amount of adhering S. mutans was reduced after aging, which may be related to the decline in SFEs.

The adhesion of Candida albicans to dental restorative materials in the human oral cavity may promote the occurrence of oral candidosis. This study aimed to compare the susceptibility of 14 commonly used composite resin materials (two compomers, one ormocer, one novel silorane, and ten conventional hybrid composites) to adhere Candida albicans. Differences in the amount of adhering fungi should be related to surface roughness, hydrophobicity, and the type of matrix. Cylindrical specimens of each material were made according to the manufacturers' instructions. Surface roughness R (a) was assessed by perthometer measurements and the degree of hydrophobicity by computerized contact angle analysis. Specimens were incubated with a reference strain of C. albicans (DMSZ 1386), and adhering fungi were quantified by using a bioluminometric assay in combination with an automated plate reader. Statistical differences were analyzed by the Kruskal-Wallis test and Mann-Whitney U test. Spearman's rank correlation coefficients were calculated to assess correlations. Median R (a) of the tested composite resin materials ranged between 0.04 and 0.23 microm, median contact angles between 69.2 degrees and 86.9 degrees . The two compomers and the ormocer showed lower luminescence intensities indicating less adhesion of fungi than all tested conventional hybrid composites. No conclusive correlation was found between surface roughness, hydrophobicity, and the amount of adhering C. albicans.