Bücher und Digitale Medien

Aim: To evaluate the fracture load and the type of failure of two different monolithic restorative materials bonded to standardized titanium bases and fabricated by two different procedures regarding the bonding-interface. Materials-Methods: All screw-retained implant-crown specimens (n=40), subjected to fatigue by thermomechanical loading, differed in the restorative material (lithium disilicate-LDS or polymer infiltrated ceramic network (PICN), referred to as “hybrid ceramic”-HYC) and the interface type between the restorative material and the titanium base abutment (prefabricated ex-factory or produced during the CAM-milling procedure). This resulted in the following groups (n=10/group): (1) LDS-M: lithium disilicate crown with a CAM-milled interface, (2) LDS-P: lithium disilicate crown with a prefabricated interface, (3) HYC-M: PICN crown with a CAM-milled interface and (4) HYC-P: PICN crown with a prefabricated interface. Aged specimens underwent static fracture load testing. The load (N) at which the initial crack occurred was denoted as Finitial, and the maximal load (N) at which the restorations fractured as Fmax. All specimens were examined under a stereomicroscope to determine the failure mode. Results: The median Finitial values were 180 N for LDS-M, 343 N for LDS-P, 340 N for HYC-M and 190 N for HYC-P. The median Fmax values were1822 N for LDS-M, 2039 N for LDS-P, 1454 N for HYC-M and 1581 N for HYC-P. The intergroup differences were significant for Finitial (KW: p = 0.0024) and for Fmax (KW: p = 0.0010). The failure types also showed differences between the restorative groups. Conclusion: The choice of restorative material had a stronger influence on the fracture load than the abutment interface workflow. Lithium disilicate showed the highest load for initial crack appearance (Finitial) and for complete fracture of the restoration (Fmax). Schlagwörter: abutment interface, dental materials, failure mode, fracture load, lithium disilicate, polymer infiltrated ceramic network, prosthetic dentistry, restorative material, thermomechanical aging

Purpose: To assess the clinical, technical, and esthetic outcomes of directly veneered zirconia abutments cemented onto nonoriginal titanium bases over a 3-year follow-up. Materials and Methods: A total of 24 healthy patients with a single missing tooth in the maxilla or mandible (incisors, canines, or premolars) received a two-piece implant with a screw-retained veneered zirconia restoration extraorally cemented onto a titanium base abutment. Baseline measurements and follow-up examinations were performed at 6 months, 1 year, and 3 years following loading. Radiographic, clinical, technical, and esthetic parameters were assessed. Wilcoxon signed rank test was used to analyze the data. Results: Mean marginal bone levels measured 0.54 ± 0.39 mm (median: 0.47 mm, range: 0.07 to 1.75 mm) at baseline and 0.52 ± 0.39 mm (median: 0.39 mm, range: 0.06 to 1.33 mm) at 3 years. Mean probing depth around the implants increased from 3.0 ± 0.6 mm at baseline to 3.8 ± 0.8 mm at 3 years (P = .001). Bleeding on probing changed from 27.1% ± 20.7% at baseline to 51.5% ± 26.1% at 3 years (P = .001). The mean plaque control record amounted to 11.1% ± 21.2% at baseline and 14.4% ± 13.89% at 3 years (P = .261). Two implants were lost at 3.5 and 30 months postloading due to periimplantitis, resulting in a 91.7% implant survival rate. Patient satisfaction was high at 3 years. Conclusion: Zirconia restorations cemented onto the tested nonoriginal titanium bases should not be recommended for daily clinical use, as they were associated with significant increases in BOP and PD values and varying marginal bone levels 3 years after placement.

Die Diagnostik ist entscheidend für den vorhersagbaren Erfolg einer restaurativen Therapie. Hierbei müssen sich Patient und Zahnarzt vor der Anfertigung der definitiven Restauration auf ein gemeinsames Behandlungsziel einigen, um später Enttäuschungen zu vermeiden. Allerdings kann es schwierig sein, die Patientenwünsche vollständig zu erfassen. Ein nützliches Hilfsmittel zur Lösung dieses Problems sind das diagnostische Wax-up und Mock-up. Mit diesem zeitaufwendigen Verfahren wird jedoch nur eine einzige Variante des möglichen Behandlungsergebnisses visualisiert. Die moderne Digitaltechnik bietet nützliche Funktionen, die bei diesem diagnostischen Schritt zu einer Entscheidungsfindung beitragen können. Im vorliegende Beitrag werden die Möglichkeiten der Digitaltechnik für die prothetische Diagnostik erörtert und die Verfahren anhand von Patientenfällen beschrieben.

Purpose: To measure the effect of simulated aging on stained resin-ceramic CAD/CAM materials regarding the durability of color and gloss. Materials and Methods: Test specimens (n = 15 per material) were prepared out of CAD/CAM ingots from two resin nanoceramics (Lava Ultimate [LVU], Cerasmart [CER]) and a polymerinfiltrated ceramic (ENA, VITA Enamic) stained with the manufacturer’s recommended staining kit using photopolymerization. Control specimens were made of feldspathic ceramic (VITA Mark II [VM2]) and stained by means of ceramic firing. Negative control specimens (n = 15) (no staining) were prepared for each group. Color and gloss measurements were performed before and after each aging cycle by means of mechanical abrasion with a toothbrush. Groups were compared using Kruskal-Wallis test and paired post hoc Conover test. Changes within a group were calculated using Wilcoxon signed-rank test (α = .05). Results: The color difference (ΔE) was statistically significant for all stained CAD/CAM materials after simulated aging: CER (P < .001, 95% CI: 2.96 to 3.69), LVU (P = .004, 95% CI: 1.09 to 1.46), ENA (P = .004, 95% CI: 0.20 to 0.42), and VM2 (P < .001, 95% CI: 0.29 to 1.08). Aging resulted in a statistically significant increase in gloss in the LVU group (P < 0.001, 95% CI: 13.78 to 17.29), whereas in the ENA (P < .001, 95% CI: 7.83 to 12.72), CER (P < .001, 95% CI: 2.69 to 8.44), and VM2 (P = .014, 95% CI: 0.22 to 1.87) groups, a significant decrease in gloss was noted. Conclusion: Color and gloss of stained resin-ceramic CAD/CAM materials changed significantly after aging by means of toothbrush abrasion in vitro.

Purpose: To investigate the effect of aging on the morphology of the interface between monolithic implant crowns and standardized titanium base abutments. Materials and Methods: Four groups of hybrid abutment crowns differing in restorative material (lithium disilicate [LD] or polymer-infiltrated ceramic network [PICN]) and in fabrication procedure of the interfacial zone for luting to a titanium abutment (milled during CAD/ CAM procedure [M] or prefabricated [P]) were formed: LDS-M, LDS-P, PICN-M, and PICN-P (n = 10 each). The morphology of the crown-abutment interface was examined before and after artificial aging using scanning electron microscopy. The total gap length per specimen was measured at both time points, and intergroup (Kruskal-Wallis [KW]) plus pairwise (Wilcoxon Mann-Whitney [WMW]) comparisons were performed (α = .05). Results: Before aging, statistically significant differences in gap length were identified among groups (KW: P = .0369) for PICN-P > LDS-P (WMW: P = .0496) and LDS-M > LDS-P (WMW: P = .0060). The effect of aging among the groups, expressed as an increment of total gap length, was 50% in LDS-M, 30% in LDS-P, 20% in PICN-M, and 30% in PICN-P. After aging, the statistically significant differences in gap length identified among groups (KW: P = .0048) were for PICN-P > LDS-P (WMW: P = .0134); LDS-M > PICN-M (WMW: P = .0204); PICN-P > PICN-M (WMW: P = .0486); and LDS-M > LDS-P (P = .0022). However, comparison of the difference in gap length from before to after aging among the groups was not statistically significant (KW: P = .3549). Conclusion: The cementation interfaces of CAD/CAM crowns on standardized titanium base abutments demonstrated a high percentage of gaps before and after thermomechanical loading. The composition of the restorative material and the nature of the interface influenced the interfacial gap dimension.

Purpose: The aim of the present study was to assess the perceptibility and acceptability threshold values for color differentiation at the restoration and mucosa levels. Materials and Methods: One restored single-tooth implant and the contralateral reference tooth were spectrophotometrically assessed in 20 patients. Perceptibility and acceptability were evaluated by dentists, dental technicians, and laypeople. Results: Dental technicians had the highest sensitivity in the perception of tooth color differences (ΔE = 2.7), followed by dentists (ΔE = 3.3) and laypeople (ΔE = 4.4). Acceptability threshold values were generally higher than perceptibility threshold in all groups. Dental technicians exhibited the highest sensitivity in the perception of mucosa color differences (50% perceptibility at ΔE = 2.65), followed by dentists (ΔE > 3.7) and laypeople (ΔE > 6). Conclusion: Color differences were tolerated with varying degrees among the three groups. Laypeople accepted higher color differences at the mucosa level.

Purpose: To assess the clinical outcomes of single-retainer resin-bonded fixed dental prostheses (RBFDPs) and the profilometric changes of pontic sites after a mean of 10 years in function. Materials and Methods: Ten patients (mean age 32.4 years) who had received an RBFDP replacing a single anterior tooth were recalled after 10 years. Five patients had received a subepithelial connective tissue graft (SCTG) at the pontic site. The clinical assessment comprised the following parameters: probing depth, bleeding on probing, modified plaque control record, gingival recession, measurement of the width of keratinized mucosa, and intraoral photographs and radiographs. The modified criteria of the United States Public Health Services evaluation system were applied. Additionally, patient satisfaction was recorded. Data were analyzed descriptively, and the 10-year RBFDP survival rates were calculated using Kaplan-Meier analysis. Results: The RBFDP survival rate after a mean follow-up of 10.0 years (range 7.4 to 13.3 years) was 100%. Neither technical failures nor biologic complications were observed. All abutment teeth remained vital, and no secondary caries were detected. Between baseline and follow-up examinations, the profilometric changes at the pontic sites were minimal, exhibiting a loss of –0.03 ± 0.10 mm (no SCTG) and 0.00 ± 0.37 mm (SCTG). Conclusion: The present study exhibited high survival rates and low complication rates of the restorations, as well as excellent profilometric stability of the pontic sites over 10 years. The use of an RBFDP is a viable long-term treatment option for replacing a single anterior tooth.

Die Diagnostik ist entscheidend für den vorhersagbaren Erfolg einer restaurativen Therapie. Hierbei müssen sich Patient und Zahnarzt vor der Anfertigung der definitiven Restauration auf ein gemeinsames Behandlungsziel einigen, um später Enttäuschungen zu vermeiden. Allerdings kann es schwierig sein, die Patientenwünsche vollständig zu erfassen. Ein nützliches Hilfsmittel zur Lösung dieses Problems sind das diagnostische Wax-up und Mock-up. Mit diesem zeitaufwendigen Verfahren wird jedoch nur eine einzige Variante des möglichen Behandlungsergebnisses visualisiert. Die moderne Digitaltechnik bietet nützliche Funktionen, die bei diesem diagnostischen Schritt zu einer Entscheidungsfindung beitragen können. Im vorliegende Beitrag werden die Möglichkeiten der Digitaltechnik für die prothetische Diagnostik erörtert und die Verfahren anhand von Patientenfällen beschrieben. Schlagwörter: CAD/CAM, Mock-up, Visualisierung, additive Fertigung, 3-D-Druck