Purpose: Evaluating the impact of the prosthetic material on implant- and prosthetic survival of implant-supported fixed complete dentures.

Study selection: Electronic and hand searches were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to identify clinical studies including at least 10 patients restored with implant-supported dentures. The primary outcome was to evaluate the implant survival rate according to the applied restorative materials. The prosthetic survival rate was evaluated as secondary outcomes.

Results: Forty-one of 2254 studies were finally selected. A statistically significant difference (p = 0.0337) was found between implant survival rates in the main restorative groups (metal-ceramic:97% (95%CI [0.96;0.98]), all-ceramic:99% (95%CI [0.98;1.00]), metal-resin:97% (95%CI [0.96;0.98])). Prosthetic survival rates were: (metal-ceramic:95% (95%CI [0.89;0.97]), all-ceramic:97% (95%CI [0.92;0.99]), metal-resin:97% (95%CI [0.95;0.98]), with no statistically significant difference (p = 0.3796) between the groups. Chipping incidence rates were as follows: metal-ceramic:8% (95%CI[0.03;0.20]), all-ceramic:15% (95%CI [0.06;0.32]), and metal-resin:22% (95%CI [0.13;0.33]).

Five types of exact restorative materials were identified (porcelain-fused-to-non-precious alloy, porcelain-fused-to-zirconia, precious-metal-acrylic-resin, non-precious-metal-acrylic resin, and PMMA). Again, implant survival rates were statistically significantly influenced by the applied restorative materials (p = 0.0126), whereas, no significant differences were reported regarding prosthetic survival rate.

Conclusions: Prosthetic material selection seems to have no clinically relevant influence on implant- and prosthetic survival rate in implant-supported fixed complete dentures. Due to the high chipping rate, quantifying prosthetic survival alone does not seem to be a reliable tool for evaluating the outcome of the restorations and providing recommendations. These results, along with the obvious lack of evidence, suggest that clinicians must exercise caution whenever porcelain-fused-to-zirconia or metal-resin restorations are considered.

Purpose: Titanium and titanium alloys are one of the main metallic materials in the medical and dental fields because of their biocompatibility. In this review, the application of titanium and its alloys as the substitute materials for Ag–Pd–Au alloy in the casting of fixed dental prostheses was examined.

Study selection: A reference search was performed through PubMed based on the keywords titanium, titanium alloy, and dental casting. Other relevant references were obtained from the citation in the articles.

Results: The dental casting technology for titanium has already been developed for clinical use, which enables the use of appropriate casting machines and investment materials for titanium and its alloys available commercially. The mechanical properties, castability, and corrosion resistance of titanium and titanium alloys were reported to be comparable or superior to the conventional dental alloys. Clinical researches reported that titanium and Ti-6Al-7Nb alloy casings showed suitable quality for clinical application.

Conclusion: Titanium and its alloys can be the substitute materials for Ag–Pd–Au alloy, and should be considered worthy of qualifying for the dental insurance coverage.

Purpose: This study was observed the effect of cleansing agents and adhesive resins on shear bond strength (SBS), surface morphology and phase transformation of saliva and silicone disclosing medium contaminated zirconia.

Methods: The 110 zirconia specimens size 5 × 5 × 1 mm were fabricated and randomly divided into 5 surface treated groups: Non-contaminated (PC) Saliva and silicone disclosing medium contaminated without cleansing (NC) Surface contaminated and cleansing with Phosphoric acid (PO) Ivoclean (IC) or Hydrofluoric acid (HF). The twenty of each surface treated specimens were selected and bonded with Panavia F2.0 (P) and Superbond C&B (S) for SBS test (n = 10). The data was analyzed by Kruskal–Wallis H and Mann–Whitney U test. The remaining specimens of each surface treated groups were examined by SEM and XRD.

Results: The saliva and silicone disclosing medium contaminated zirconia without cleansing group (PNC) had the lowest SBS when Panavia F2.0 was used for cementation (p < 0.05). The SBS of surface cleansing groups (PPO, PIC and PHF) were not different from the non-contaminated group (PPC) (p > 0.05). However, there were no difference in SBS among groups when cementation with Superbond C&B (SPC, SNC, SPO, SIC and SHF) (p > 0.05). There was no morphologic changing that could be observed by SEM. The XRD showed little phase transformation when surfaces were contaminated and cleaned.

Conclusions: The saliva and silicone disclosing medium contaminated zirconia should be cleaned with Phosphoric acid, Ivoclean or Hydrofluoric acid for 20 s prior to cementation with Panavia F2.0. However, the surface cleansing was not necessary when cementation with Superbond C&B.

Purpose: To investigate if sleep bruxism (SB) influences training-induced cortical plasticity and performance in terms of accuracy and precision of a tooth-clenching task (TCT).

Methods: Thirty-eight participants were allocated into SB group (N = 19) and control group (N = 19) according to presence of SB based on a 2-week screening. The participants were instructed to perform a standardized TCT for 58 min at three different force levels (10%, 20% and 40% of maximum voluntary contraction; MVC) in three series (first and third without visual-feedback and second with visual-feedback). Accuracy and precision of the TCT were calculated from actual bite force values. Transcranial magnetic stimulation was applied to elicit motor evoked potentials (MEPs) from the masseter and first dorsal interosseous muscle (FDI) before the TCT (pre-TCT-session) and 5-min after the TCT (post-TCT-session).

Results: Accuracy was significantly dependent on the series and target force level (P < 0.001), however, there was a significant decrease only in the control group at 10% MVC from first to third session (P < 0.001). No significant differences between groups were observed for the precision of the TCT. Masseter MEPs in the SB group in the pre-TCT-session at 120% and 160% motor threshold were significantly lower than in the control group (P < 0.05). Masseter MEPs of the control group in the post-TCT-session were significantly higher than the pre-TCT-session (P < 0.05) but not SB. FDI MEPs were only dependent on stimulus intensity (P < 0.001).

Conclusions: SB is associated with significant changes not only in excitability of corticomotor control but also motor learning of jaw movements and force control.

Purpose: Animal experiments have shown that the loss of occlusal support causes impairments in spatial cognition. Many reports have focused on the memory encoding process, and only few studies have investigated the effect on memory retrieval. This study aimed to examine the effects of both the loss and reconstruction of occlusal support on the memory retrieval process and on the number of hippocampal pyramidal cells.

Methods: The experimental animals were divided into a molarless group, in which molars were extracted, a denture-wearing molarless group with experimental dentures inserted after molar extraction, and a control group. Radial maze trials were performed for 20 consecutive days (acquisition phase). The rats were tested on long-term memory retention following the acquisition phase in eight trials every five days, and in an additional trial 20 days later (probe phase).

Results: The denture-wearing molarless group showed higher levels of spatial learning and memory than the molarless group. There were no significant differences in memory retrieval during the probe phase between the denture-wearing molarless and the control group. The molarless group showed significantly worse spatial learning and memory and had fewer neurons in the hippocampus than the control group.

Conclusions: Our results suggest that the loss of occlusal support decreases the number of pyramidal cells in the hippocampus and impairs memory decoding and retrieval. However, this effect is suppressed by the reconstruction of occlusal support.

Purpose: Providing appropriate dental prostheses and dietary interventions may improve food and nutrient intake in elderly edentulous patients, but evidence to support their use is scarce. In this trial, we aimed to clarify the combined effect, on the nutritional statuses of edentulous elderly patients, of dentists providing complete dentures with dietary advice.

Methods: A randomized-controlled trial was performed on a healthy elderly population who required new complete dentures. All participants had new complete dentures fabricated and were randomly divided into an intervention or a control group. The intervention group received simple dietary advice through standardized patient information leaflets and the control group received advice on denture care only. Nutritional status was assessed using the Mini Nutritional Assessment short-form (MNA-SF) before and at 3 and 6 months after treatment. At each assessment point, the MNA-SF scores were compared using the Mann–Whitney U test. The within-group differences in the MNA-SF scores were analyzed using the Wilcoxon signed-rank test with Bonferroni correction.

Results: In total, 59 participants completed all trial steps. At 6 months after treatment, the MNA-SF score in the intervention group was significantly higher than that in the control group (p = 0.01). Comparing the within-group changes in the MNA-SF score revealed that the score increased significantly from 3 to 6 months in the intervention group (p = 0.001, Bonferroni correction).

Conclusions: Nutritional statuses of healthy edentulous elderly population might be improved by fabricating new complete dentures and providing simple dietary advice.

Purpose: To examine the effect of mandibular ridge form and denture quality on oral health-related quality of life (OHRQoL) in complete denture wearers by using structural equation modeling (SEM) analysis of data before and after new complete denture insertion.

Methods: Four hundred thirty-two edentulous patients who visited the Dental Hospital of Tokyo Medical and Dental University for new complete dentures were recruited. An intervention study design was conducted, including complete denture fabrication with SEM analysis. Mandibular ridge form, mandibular denture stability, accuracy of jaw relation record, and the Oral Health Impact Profile for edentulous subjects (OHIP-EDENT-J) total score before and after new complete denture insertion were used in the hypothesized model.

Results: Two hundred and thirty-seven participants completed the research. SEM analysis demonstrated adequate model fit. Path coefficients of mandibular ridge form to OHIP-EDENT-J before and after insertion, and mandibular denture stability to OHIP-EDENT-J before insertion, were significant.

Conclusions: This study demonstrated that mandibular denture stability and mandibular ridge form are important to ensure successful complete denture therapy.

Purpose: This study aimed to investigate whether the mandible is more receptive to external stimuli than the maxilla in patients with complete dentures by comparing regional current perception thresholds (CPTs) and pain threshold (PTs).

Methods: A single operator obtained measurements from maxillae at the incisor foramen and the left side of the greater palatine foramen region and the mandible at the left side of the mental foramen region, using the Neurometer CPT/C device, CPT and PT values from the oral mucosa of 20 edentulous individuals wearing complete dentures were analyzed. Participant characteristics such as mucosal thickness, occlusal force, age, and sex. Mucosal thickness over target regions and occlusal force were measured by the same operator using Krupp SDM and Occlusal Force-Meter GM10s devices. Differences in CPT and PT among the three measurement regions were tested with an analysis of covariance, and post hoc t-tests with the Bonferroni correction.

Results: There were no significant differences between the mental foramen, incisor papilla, and greater palatine regions CPT values. PTs obtained at all current frequencies (2000 Hz, 250 Hz, and 5 Hz) were lowest in the mental foramen region and highest in the greater palatine region. Covariates including sex, mucosal thickness, and occlusal force had no significant influence on CPT or PT values at all frequencies.

Conclusions: The mandible exhibits higher receptivity to external pain stimuli than the maxilla.

Purpose: The purpose of this study was to determine the effect of block-out preparation, used to eliminate the undercut area, on the retentive force and stress distribution of resin clasps.

Methods: A total of 72 polyester and polyamide resin clasps were fabricated on a premolar abutment crown following six block-out preparations. A combination of two types of vertical block-outs and three types of horizontal block-outs (on the missing side) was used on the abutment tooth. Each clasp was subjected to an in vitro removal test using a universal testing machine. The retentive force and traces of the clasp on the abutment tooth were recorded and analyzed with one-way analysis of variance and post hoc comparisons (α = 0.05). Non-linear finite element analysis was performed to assess the stress distributions of the resin clasps.

Results: Resin clasps with a vertical block-out of 0.75 mm undercut showed significantly higher retentive force than those with the 0.5 mm undercut. Resin clasps with horizontal block-out showed significantly lower retentive force than those without horizontal block-out. There was no significant difference between the two thermoplastic resins. The maximum first principal stress of the resin clasp was concentrated under the shoulder of the clasp and strongly influenced by the width of horizontal block-out in the finite element analysis.

Conclusions: This in vitro experiment suggested that a horizontal block-out is necessary even for a 0.5-mm undercut. The design of the resin clasp should be considered from two aspects: retentive force and deformation risk.

Purpose: To assess the current status of patients with dental metal allergies in Japan.

Methods: This study analyzed dental metal allergy in 1225 patients (1:3 male to female ratio; average age 53.0 ± 16.5 years), including 300 who were scheduled to undergo dental implant surgery, between 2006 and 2016. For diagnosis of metal allergy, patch tests using metal allergens were performed. Additionally, when necessary, metal element analysis of dental alloys was performed in the mouths of some patients using an X-ray fluorescence analyzer for those who exhibited positive reactions.

Results: Among 925 patients (i.e., excluding those scheduled to undergo dental implant surgery [n = 300]), nearly one-half (44.0%) exhibited a positive response to any metal element in the patch test. The positivity rates were as follows: nickel (22.5%); palladium (14.8%); and zinc (11.5%). Almost one-half (42.3%) of the patients had diseases associated with metal allergy. Among patients who exhibited a positive reaction to any metal element in the patch test, more than two-thirds (67.9%) had dental alloys containing the positive metal element (s). One-half (55.6%) of the patients who underwent treatment to remove the metal experienced improvement in symptoms. In patients who underwent patch testing as an implant preoperative examination, several (2.7%) exhibited a positive reaction to titanium.

Conclusions: Dental metals, including nickel, palladium and zinc, which are indispensable to dental treatment in Japan, had high positivity rates in patch testing, and one-half of the patients improved following removal of the metal. Additionally, there were several patients with allergy to titanium.

Purpose: To set up the digital database (DDB) of various anatomical parts, skin details and retention elements in order to simplify the digital workflow of facial prostheses manufacturing; and to quantify the reproduction of skin wrinkles on the prostheses prototypes with stereolithography (SLA) and direct light processing (DLP) methods.

Methods: Two structured light scanners were used to obtain the nasal and auricle forms of 50 probands. Furthermore, the ala nasi and scapha areas were captured with the digital single lens reflex camera and saved in jpeg format. The four magnetic retention elements were remodeled in computer aided design (CAD) software. The 14 test blocks with embossed wrinkles of 0.05–0.8 mm were printed with SLA and DLP methods and afterwards analyzed by means of profilometry and confocal microscopy.

Results: The introduced DDB allows for production of customized facial prosthesis and makes it possible to consider the integration of concrete retention elements on the CAD stage, which makes the prosthesis modelling more predictable and efficient. The obtained skin structures can be applied onto the prosthesis surface for customization. The reproduction of wrinkles from 0.1 to 0.8 mm in depth may be associated with the loss of 4.5%–11% of its profile with SLA or DLP respectively. Besides, the reproduction of 0.05 mm wrinkles may be met with up to 40% profile increasement.

Conclusions: The utilization of DDB may simplify the digital workflow of facial prostheses manufacturing. The transfer of digitally applied skin wrinkles till the prostheses' prototypes may be associated with deviations from 11 to 40%.

Purpose: To evaluate the substrate masking ability of different ceramic systems used for complete crowns and assess the influence of their association with an opaque resin-based luting agent (OLA).

Methods: Eleven ceramic groups were tested (n = 10). Bilayer groups were: ZrPc — zirconia + porcelain; CAD-onHT — zirconia + high translucent lithium disilitace; CAD-onLT — zirconia + low translucent lithium disilicate; LDPc — high opaque lithium disilicate + porcelain. Monolithic groups were: TZ — high translucent zirconia; TLS — translucent, zirconia-reinforced lithium silicate; HTLS — high translucent, zirconia-reinforced lithium silicate; LTLD — low translucent lithium disilicate; HTLD — high translucent lithium disilitace; LGC — leucite-reinforced glass ceramic; FC — feldsphatic ceramic. The substrates adopted were resin composites shaded A1 (control), A3.5 and C4; coppery and silvery metals. Color differences (ΔE₀₀) and translucency parameter (TP₀₀) were assessed with the CIEDE2000 formula. ΔE₀₀ was obtained assessing the ceramic influence only and in association with OLA.

Results: Zirconia groups presented lower ΔE₀₀ and TP₀₀. CAD-on structures associated to OLA led to the lower ΔE₀₀ when tested over metals. ΔE₀₀ for LDPc were similar to zirconia when associated to OLA. Monolithic groups presented significant higher ΔE₀₀ and TP₀₀ compared to bilayers, with ΔE₀₀ below the acceptability threshold only when associated to OLA over substrate shade A3.5.

Conclusions: Ceramic type and the white-opaque resin-based luting agent presented a significant effect on the substrate masking ability. All the discolored substrates tested are adequately masked with veneered zirconia or with LDPc (preferably associated to OLA). The CAD-on technique associated with OLA improved the masking ability over metallic substrates.

Purpose: Modal analysis has been used to monitor and quantify the vibration of each component of a prosthesis at its natural frequency. An understanding of the vibrational characteristics of a prosthesis can guide selection of the appropriate prosthesis configuration to prevent excessive stress. In this study, modal analysis of fixed implant-supported prostheses with 4 or 6 abutments in edentulous maxillae was performed.

Methods: Sixteen patients underwent maxillary dental implant treatment and received screw-fixed implant-supported prostheses (9 patients received 4-abutment prostheses and 7 patients received 6-abutment prostheses) in edentulous maxillae. An impact hammer was used for excitation of the prostheses, and vibration was detected on every crown of the prostheses. The modal parameters were determined in each subject. Furthermore, the modal shapes were compared at each natural frequency.

Results: The median natural frequencies of subjects with 4- and 6-abutment prostheses were 697 and 781 Hz, respectively. The mean damping ratios did not differ significantly between 4- (8.2 ± 1.7%) and 6-abutment (6.6 ± 1.7%) prostheses (p = 0.125). The mean maximum displacements of fixed prostheses were significantly lower for 6-abutment (10.3 ± 3.3 μm) than for 4- (20.3 ± 9.1 μm) prostheses (p = 0.004). The median number of vectors in antiphase was significantly lower for 6- (4) than for 4-abutment prostheses (14) (p = 0.001).

Conclusions: The current study demonstrated less adverse vibration in the 6-abutment prostheses than in the 4-abutment prostheses, suggesting that modal analysis can contribute to novel future developments in the designs of dental implant prostheses.

Purpose: The aim of this study was to prospectively compare the clinical performance of veneered zirconia cantilever fixed partial dentures (Z-CFPDs) and metal–ceramic CFPDs (MC-CFPDs) over 9 years of follow-up in terms of survival.

Methods: Twenty-one participants were assigned by simple randomization to receive either 1 Z-CFPD (n = 11) or 1 MC-CFPD (n = 10). CFPDs were retained by 2 full crowns and replaced a missing premolar or a central or lateral incisor. Modified USPHS (United States Public Health Service) criteria were used to classify material chipping, retention, marginal integrity, secondary caries, and color of the restorations. The satisfaction of the study participants with the esthetics of their restorations was surveyed; pocket probing depths (PPD), plaque index (PI), and gingival index (GI) were also measured. Study groups were compared by use of U tests (continuous variables), or by use of Fisher exact probability tests (categorical variables) with α = 0.05.

Results: Sixteen participants (n = 8 with a Z-CFPD and n = 8 with an MC-CFPD) attended the 9-year follow-up examination (response rate: 76.2%). Over the 9-year study period, survival of 50% for Z-CFPDs and 75% for MC-CFPDs was recorded (p = 0.608). No framework fractures occurred, and no statistically significant differences were observed between the groups regarding changes in PPD, PI, GI, or participant satisfaction (p > 0.05). USPHS criteria revealed statistically significantly poorer marginal quality for Z-CFPDs than for MC-CFPDs (p = 0.009).

Conclusions: Within the limitations of this study, Z and MC-CFPDs demonstrated no statistically significant difference in terms of survival.

Purpose: This study aimed to evaluate the effects of chemical conditioning and self-adhesive resins (SARs) on the bonding of mechanically conditioned high-strength composite resin block (HSCRB).

Methods: Eighteen sections of HSCRB (KZR-CAD HR 3 Gammatheta, Yamakin) were treated with alumina air abrasion and randomly divided into 3 groups according to the SARs for bonding: RelyX Unicem 2 (RXU), SA Luting Plus (SAL), and G-Cem ONE (GCO). The sections were further divided into 3 subgroups according to the chemical conditioning of the adherend surfaces: no conditioning (C), universal adhesive (UA), and a mixture of γ-MPTS and 10-MDP (MM). After the surface conditioning, the sections were cemented with the SARs. Each cemented section was cut into 40 beams. Half of the beams were thermocycled (4 °C/60 °C, 10,000 cycles). The micro-tensile bond strength (μTBS) values were measured using a universal testing machine. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), contact angles, and surface roughness measurements were performed on the adherend surfaces of each subgroup.

Results: RXU showed the highest μTBS values among the 3 SARs tested, while MM application exhibited the highest μTBS values among the 3 chemical conditioning methods tested. After thermocycling, the samples in the RXU/MM, RXU/UA, and GCO/MM groups showed no significant changes in the μTBS values, whereas the others showed a significant reduction.

Conclusions: The bond strength of HSCRB was influenced by the chemical conditioning, SARs, and aging. γ-MPTS and 10-MDP application yielded higher μTBS values of mechanically treated HSCRB than the UA.

Purpose: To investigate the impact of inlay design and number of retainer wings on the failure load of all-ceramic resin-bonded inlay-retained cantilever fixed dental prostheses (IRCFDPs) made from a computer-aided design/computer-aided manufacturing (CAD/CAM) yttrium-oxide partially-stabilized zirconia framework (Y-TZP).

Methods: Sixty-four extracted human first molars were divided according to preparation design into four groups. Teeth were provided with IRCFDPs representing a premolar pontic and a retainer of variable design: (R1S) shallow inlay/one lingual retainer wing, (R2S) shallow inlay/two retainer wings (lingual/buccal), (R1D) deep inlay/one lingual retainer wing and (R2D) deep inlay/two retainer wings (lingual/buccal). All IRCFDPs were cemented using adhesive resin. Quasi-static fracture strength (QSFS) was tested for 32 specimens after 3 days in a universal testing machine (UTM). The other specimens were stored in a water bath (150 days/37°C) and thermocycled (37,500 times, 5-55°C); then exposed to dynamic loading in a chewing simulator (50 N/1,200,000 cycles).

Results: The median QSFS (N) for the different designs were: R1S:105.1, R1D:167.5, R2S:147.9, R2D:232.3. The number of retainer wings had a statistically significant influence on the fracture load of both groups, whereas the inlay design had an impact only in the double-retainer wing group. Under dynamic loading, lower failure loads within all groups were reported except for the group R2S. The number of retainer wings continued to significantly influence the failure loads of both groups, whereas no influence of inlay design could be revealed.

Conclusions: Double-retainer IRCFDPs showed promising results for replacing single premolars. The inlay design seems to have no significant influence on the fracture strength of these restorations.

Purpose: To investigated the effect of vibratory stimulus on masseter muscles during oral fine motor biting tasks.

Methods: Sixteen healthy individuals (age: 24.5 ± 2.4 years) participated in experiment I during which the participants were asked to "hold and split" half a roasted peanut placed on a force transducer with their front teeth. The participant performed ten series with ten trials of the "hold and split" behavioral task while vibratory stimulus was applied on the masseter muscle every alternate series. Further, fourteen participants participated (age: 25.2 ± 4.8 years) in experiment II during which they performed a series each of the behavioral task at baseline, an adjusted baseline without and with vibration as well as with and without visual feedback. Hold and split forces along with the variability of hold force and duration and force rate during the split were measured.

Results: The results of the study showed an increase in the magnitude of the hold force (P = 0.002), force rate during the split (P < 0.001) and a significant decrease in the duration of split (P < 0.001) due to the vibratory stimulus. However, there was no significant effect of the vibratory stimulus on the variability of hold forces (P = 0.879) or mean split force (P = 0.683) during the "hold and split" behavioral task. The results of experiment II also showed an increase in hold force due to the vibratory stimulus (P < 0.001).

Conclusions: Vibratory stimulus to the masseter muscles impairs the oral force control during a standardized biting task and provide further insight into the sensorimotor regulation of the masticatory system.

Purpose: To test three potential prosthetic material options for zirconia implants in regard to their mechanical properties, loading and retention capacity as well as to record abrasion after chewing simulation followed by thermocyclic aging.

Methods: Molar crowns (n = 96) of three different computer-aided design/computer-aided manufacturing (CAD/CAM) materials were produced and cemented on zirconia implants (ceramic.implant, Vita) with a diameter of 4.5 mm. Monolithic zirconia (Vita YZ [YZ] with RelyX Unicem 2 Automix [RUN], polymer-infiltrated ceramic (Vita Enamic [VE]) with Vita Adiva F-Cem [VAF] and acrylate polymer (CAD Temp [CT]) with RelyX Ultimate [RUL]. Fracture load and retentive force of the crowns were measured after 24 h water storage at 37 °C and after a chewing simulation followed by thermocyclic aging. Abrasion was recorded by matching stereolithography-data of the crowns obtained before and after chewing simulation. Additionally, the mechanical properties and bonding capabilities of the crown and cement materials were assessed.

Results: Fracture load values were significantly highest for YZ > VE = CT. Retention force values did not differ significantly between the materials. The aging procedure did not affect the fracture load values nor the retention force significantly. Abrasion depth of the crowns was lowest for YZ followed by VE and CT. On unpolished crowns, abrasion of YZ and VE tended to be higher than on polished specimens.

Conclusions: Based on the obtained in-vitro results, all tested materials can be recommended for the use on zirconia implants, although CT is only approved for temporary crowns. The loading and retention capacity of the materials were not significantly affected by aging.

Purpose: To analyse fatigue damage of monolithic computer-aided-designed/computer-aided-manufactured (CAD/CAM)-materials after loading with high masticatory forces in standardized posterior crowns in a mouth-motion-simulator.

Methods: For manufacturing of test specimens (5 groups, 16 specimens each), two corresponding Standard-Tessellation-Language-(STL)-data-sets (one for the teeth and one for the crowns) were designed. The teeth were CAD/CAM-milled of human third molars and the crowns of three different CAD/CAM composite blocks (Lava Ultimate, 'LU'; Brilliant Crios 'BC'; Cerasmart, 'CS'), one polymer-infiltrated-ceramic network (Vita Enamic, 'VE') and a control group of lithium disilicate ceramics (IPS e.max CAD, 'EM'). Crowns were adhesively cemented with their corresponding luting system on the human teeth. Half of the specimens were light-cured ('LC') and the others were chemical-cured ('CC'). A mouth-motion-simulator (WL-tec, 2 Hz, 37 °C) applied dynamic cyclic loading between 50–500 N for a period of 1 million cycles. Afterwards, a dye penetration test (aqueous basic-fuchsine) revealed damage of test specimens. Each specimen was sectioned into four equidistant slices and the area without damage was measured with a digital microscope (Zeiss) and radial cracks at the cementation surface were assessed. Data were subjected to Tukey's test.

Results: All specimens showed fatigue damage in the occlusal contact area. LU, BC and CS exhibited a significant greater area without damage compared to VE and EM (p <.05). EM and VE showed additional radial cracks at the cementation interface in both curing modes, whereas LU, BC and CS showed only radial cracks with chemical-cured luting cement.

Conclusions: Monolithic CAD/CAM composite crowns showed significantly lower fatigue damage, particular if the luting system was light-cured.

Purpose: We clarified cumulative survival and event-free rates of resin-bonded fixed dental prostheses (RBFDPs) and compared them to those of fixed dental prostheses (FDPs) to refine risk factors for non-survival/event and use of tooth extraction after the period of non-survival/event.

Methods: Study subjects were selected among all patients who consecutively attended the Fixed Prosthodontic Clinic of Okayama University Hospital. Eligible patients were those who received 3-unit metal-framed 2-retainer (wing–wing) RBFDPs or conventional full-coverage FDPs (RBFDPs/FDPs: 129/177 prostheses). Data were analyzed by Kaplan–Meier analysis with the log-rank test, Mann–Whitney test, chi-square test, and Cox proportional hazards analysis.

Results: The 15-year cumulative survival rates were 66.5% for the RBFDP group and 61.6% for the FDP group, which were not significantly different (p = 0.59). The 15-year cumulative event-free rates were 53.4% for the RBFDP group and 59.2% for the FDP group, which were not significantly different (p = 0.52). No significant risk factors related to non-survival and event-free of RBFDPs/FDPs were identified in the analysis model using treatment method, sex, age, number of remaining teeth, and treatment site as explanatory variables. The number of cases in which RBFDPs/FDPs resulted in non-survival due to abutment tooth extraction was significantly lower in RBFDPs (p < 0.01). Further, the abutment tooth as a non-vital tooth was identified as a risk factor for RBFDPs/FDPs resulting in non-survival due to abutment tooth extraction.

Conclusions: The present study is the first to indicate RBFDP as a prosthetic treatment option which should be selected for patients with slight or no abutment tooth decay.