The aim of this study was to compare the clinical properties of tooth-colored computer-aided design/computer-aided manufacturing (CAD/CAM) materials for the fabrication of a 3-unit fixed dental prostheses (FDPs) in the same clinical scenario. A 53-year-old female patient was supplied with a 3-unit FDP to replace a second premolar in the upper jaw. Restorations were fabricated from 3 mol%, 4 mol%, and 5 mol% yttrium oxide zirconia, zirconia with translucency gradient, indirect composite resin, polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). Milling time, weight, and radiopacity were investigated. Esthetics were examined following the US Public Health Service criteria (USPHS). The milling time for zirconia was twice as high as for the indirect composite resin, PEEK, or PEKK. The latter materials had a weight of 2 g each, while zirconia restorations yielded 5 g. Zirconia presented intense radiopacity. PEEK and PEKK required veneering and an opaquer was applied to the PEKK framework. All FDPs showed acceptable esthetics. PEEK and PEKK restorations were featured by a grayish shimmering. A variety of CAD/CAM materials are available to fabricate 3-unit FDPs with esthetically acceptable results. In the esthetic zone, PEEK and PEKK require veneering and an opaquer might be applied. Milling time, weight, and radiopacity were relatively high for zirconia FDPs.

Denture prostheses are an ideal and extensive reservoir for microorganisms to attach to their surfaces. The aim of the study was to elucidate interactions between materials for the fabrication of denture bases and the attachment of microorganisms, focusing on respiratory pathogens and Candida species. Specimens (6 mm × 1 mm) with a standardized surface roughness (Sa = 0.1 µm) were prepared from heat-pressed polymethyl methacrylate (PMMA), CAD/CAM-processed PMMA, and CAD/CAM-processed polyether ether ketone (PEEK). The specimens were randomly placed in the vestibular areas of complete upper dentures in seven patients and were removed either after 24 h without any oral hygiene measures or after a period of four weeks. The microorganisms adherent to the surface of the specimens were cultivated and subsequently analyzed using mass spectrometry (MALDI-TOF). The means and standard deviations were calculated, and the data were analyzed using a two-way analysis of variance (ANOVA) and Tukey post-hoc test where appropriate (α = 0.05). There was a significant increase (p ≤ 0.004) in the total bacterial counts (CFU/mL) between the first (24 h) and the second (four weeks) measurements. Regarding quantitative microbiological analyses, no significant differences between the various materials were identified. Respiratory microorganisms were detected in all samples at both measurement time points, with a large variance between different patients. Only after four weeks, Candida species were identified on all materials but not in all participants. Candida species and respiratory microorganisms accumulate on various denture base resins. While no significant differences were identified between the materials, there was a tendency towards a more pronounced accumulation of microorganisms on conventionally processed PMMA.

The aim of this study was to analyze the optical properties of current CAD/CAM silicate glass-ceramics and the context of their structural properties. Different glass-ceramics (VITABLOCS Mark II, Nice, Celtra Duo, IPS e.max CAD) were prepared at the manufacturer-specific translucency level (LT/MT/HT/O2/O1) in disc form (0.5/1.0/1.5 mm thickness) and examined via a benchtop spectrophotometer (X-Rite Ci76000). TP_ab, TP₀₀ (translucency), the CR (contrast ratio), ΔE₀₀ (masking ability), OP_RT (opalescence) and FL (fluorescence) were calculated. The microstructure was analyzed via powder X-ray diffraction (XRD) with Rietveld refinement and scanning electron microscopy (SEM). With increasing sample thickness, TP_ab and TP₀₀ decreased, and the CR increased. IPS e.max CAD showed the highest (Emax_O1) and lowest (Emax_LT) translucencies. Thickness had no clear effect on ΔE₀₀, OP_RT or FL. Emax_O1/O2 generally presented very high OP_RT and FL values. All the ceramics had different phase components and glass contents. The glass content of MarkII was the highest, and that of Nice_LT/HT was the lowest. The translucency increased within a particular product line (Nice, Celtra or Emax) with increasing glass content. No correlation between the glass content and optical properties was observed between the different glass-ceramics MarkII, Nice, Celtra and Emax. Furthermore, no correlation was found between the crystallite shape/size and optical properties. To match dental restorations with the aesthetics of natural teeth, knowledge of the optical properties of glass-ceramics is important.

The aim of the study was to analyze the translucency, opalescence, and fluorescence of enamel and dentin of extracted human teeth, as well as the influence of storage time. Thirty-eight extracted human teeth were embedded in epoxy resin within 12 h post-extraction. After 48 h, 0.5 mm thick buccolingual sections were prepared and polished. Specimens were stored in 0.5 % chloramine T-hydrate solution at 6±1 °C. Reflectance measurements were performed using a spectrophotometer (Ci7600, X-Rite) with a round aperture (diameter: 3.5 mm) in SCI mode against black and white backgrounds. Translucency (TP_ab, TP₀₀), opalescence (OP_BW), and fluorescence (FL) were calculated for enamel and dentin separately at storage times of 7, 14, 21, and 28 days, and at three and six months. The following values were found for human teeth: Enamel: TP_ab: 21.5-24.2 (SD: 3.5-4.3); TP₀₀: 16.8-19.4 (SD: 3.2-4.1); OP_BW: 11.2-12.5 (SD: 1.5-2.0); FL: 3.8-5.0 (SD: 1.1-1.7); Dentin: TP_ab: 15.6-17.0 (SD: 4.2-4.6); TP₀₀: 11.5-12.6 (SD: 3.3-3.5); OP_BW: 9.3-9.6 (SD: 1.9-2.5); FL: 6.0-7.5 (SD: 1.6-2.5). Storage time only had an effect on the enamel, with a significant increase (p<0.05) in TP_ab (+2.7), TP₀₀ (+2.6), and OP_BW (+1.3) observed after six months of storage. Storage time is a significant factor for the optical properties of enamel, leading to increased translucency and opalescence after six months. In contrast, the optical properties of dentin remain largely stable. The development and assessment of aesthetic dental materials requires a quantification of the optical properties of human teeth, as well as knowledge of influencing factors during the examination.

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.