Purpose: Titanium based implant systems, though considered as the gold standard for rehabilitation of edentulous spaces, have been criticized for many inherent flaws. The onset of hypersensitivity reactions, biocompatibility issues, and an unaesthetic gray hue have raised demands for more aesthetic and tissue compatible material for implant fabrication. Zirconia is emerging as a promising alternative to conventional Titanium based implant systems for oral rehabilitation with superior biological, aesthetics, mechanical and optical properties. This review aims to critically analyze and review the credibility of Zirconia implants as an alternative to Titanium for prosthetic rehabilitation.

Study selection: The literature search for articles written in the English language in PubMed and Cochrane Library database from 1990 till December 2016. The following search terms were utilized for data search: "zirconia implants" NOT "abutment", "zirconia implants" AND "titanium implants" AND "osseointegra- tion", "zirconia implants" AND compatibility.

Results: The number of potential relevant articles selected were 47. All the human in vivo clinical, in vitro, animals' studies were included and discussed under the following subheadings: Chemical composition, structure and phases; Physical and mechanical properties; Aesthetic and optical properties; Osseointegration and biocompatibility; Surface modifications; Peri-implant tissue compatibility, inflammation and soft tissue healing, and long-term prognosis.

Conclusions: Zirconia implants are a promising alternative to titanium with a superior soft-tissue response, biocompatibility, and aesthetics with comparable osseointegration. However, further longterm longitudinal and comparative clinical trials are required to validate zirconia as a viable alternative to the titanium implant.

Purpose: The purpose of this review was to analyze existing literature on the relationship between tooth count and mortality by evaluating the findings in the context of methodological variations. We aimed at addressing the question of whether preserving natural teeth can impact mortality.

Study selection: PubMed, Web of Science and CINAHL databases were systematically searched using various combinations of related and synonymous keywords for "tooth count" and "mortality". The references of included articles were also evaluated for inclusion. Overall 49 studies found to be eligible were critically evaluated and their key findings were summarized.

Results: Studies were conducted in various continents and differed substantially in regards to their sample size, population, methodology, the definition of the tooth count variable, the confounders as well as the mediators accounted for in the analysis. Follow-up period ranged from 1 to 56 years.

Conclusions: Although high variability in the studies precludes a definite conclusion about the relationship between number of teeth and mortality, the overall finding from this review is that reduced tooth count is associated with higher mortality. However the impact of factors such as smoking, healthcare access, baseline co-morbidity and risk profile, dental and periodontal health, the presence of dental prosthesis as well as socio-economic status, in mediating whole or part of the association cannot be overlooked and needs further investigation using more standard methodologies. Any differences in males vs. females, as well as among different age groups, will also need further consideration in the future studies.

Purpose: Alveolar ridge augmentation is essential for success in implant therapy and depends on the biological performance of bone graft materials. This literature review aims to comprehensively explain the clinically relevant capabilities and limitations of currently available bone substitutes for bone augmentation in light of biomaterial science.

Study selection: The biological performance of calcium phosphate-based bone substitutes was categorized according to space-making capability, biocompatibility, bioabsorption, and volume maintenance over time. Each category was reviewed based on clinical studies, preclinical animal studies, and in vitro studies.

Results: Currently available bone substitutes provide only osteoconduction as a scaffold but not osteoinduction. Particle size, sensitivity to enzymatic or chemical dissolution, and mechanical properties affect the space-making capability of bone substitutes. The nature of collagen fibers, particulate size, and release of calcium ions influence the biocompatibility of bone substitutes. Bioabsorption of bone substitutes is determined by water solubility (chemical composition) and acid resistance (integrity of apatite structure). Bioabsorption of remnant bone substitute material and volume maintenance of the augmented bone are inversely related.

Conclusion: It is necessary to improve the biocompatibility of currently available bone substitutes and to strike an appropriate balance between bioabsorption and volume maintenance to achieve ideal bone remodeling.

Purpose: The Japan Prosthodontic Society developed a multi-axis assessment protocol to evaluate the complex variations in patients who need prosthodontic care, and to classify the level of treatment difficulty. A previous report found the protocol to be sufficiently reliable. The purpose of this multi-center cohort study was to evaluate the validity of this multi-axis assessment protocol.

Methods: The treatment difficulty was evaluated using the multi-axis assessment protocol before starting prosthodontic treatment. The time required for active prosthodontic treatment, medical resources such as treatment cost, and changes in the oral health-related QOL before and after treatment, were evaluated after treatment completion. The construct validity of this protocol was assessed by the correlation between the dentist's pre-operative subjective assessment of the treatment difficulty, and the level of difficulty determined by this protocol. The predictive validity was assessed estimating the correlations between a "comprehensive level of treatment difficulty" based on the four axes of this protocol and total treatment cost, total treatment time, and changes in the oral health-related QOL before and after treatment.

Results: The construct validity of this protocol was well documented except for psychological assessment. Regarding the predictive validity, the comprehensive level of treatment difficulty assessed before treatment was significantly correlated with the three surrogate endpoints known to be related to the treatment difficulty (total treatment cost, treatment time, and improvement in the oral health-related QOL). To further clarify the validity of the protocol according to patients' oral condition, a subgroup analysis by defects was performed. Analyses revealed that treatment difficulty assessment before treatment was significantly related to one or two surrogate endpoints in the fully edentulous patients and the partially edentulous patients. No significant relationship was observed in the patients with mixture of full/partial edentulism and the patients with teeth problems, possibly due to the small sample size in these groups.

Conclusion: This study revealed that the multi-axis assessment protocol was sufficiently valid to predict the level of treatment difficulty in prosthodontic care in patients with fully edentulous defects and with partially edentulous defects.

Purpose: The aim of the study was to compare strength of the anterior teeth restored with ceramic endocrowns versus custom-made post and core.

Methods: The investigation used the finite element analysis. Three 3-D models of maxillary central incisor were created: model A—tooth restored with metal post and core with ceramic crown; model B—tooth with leucite ceramic endocrown; model C—tooth with lithium disilicate ceramic endocrown. Each model was subjected to a 100N force applied at a distance of 5 mm from the incisal edge, at the angle of 130° to the long axis of the tooth. The modified von Mises failure criterion was used to evaluate the strength of the dentin, ceramic and resin cement, and Huber–Mises–Hencky failure criterion for cast alloy. Contact stresses in the cement-tissue adhesive interface were calculated.

Results: The lowest stresses occurred in the anterior tooth restored with custom post and core (model A). The mvM stress of 47.5 MPa concentrated in leucite ceramic endocrown (model B) and its value was close to the tensile strength of this material. The maximal mvM stresses in the lithium disilicate ceramic endocrown (model C) were 4 times lower than tensile strength of this material. In all cases contact stresses in the adhesive interface under restorations did not exceed the resin cement bond strength to dentin.

Conclusions: Leucite ceramic endocrowns in incisors may fracture during physiological loading. Endocrowns made of lithium disilicate ceramic are resistant to failure. Posts and prosthetic crowns are still recommended for anterior teeth restorations.

Purpose: The present study aimed to elucidate how saliva contamination affects microtensile bond strength of resin cement to CAD/CAM resin blocks and identify a decontamination method that can restore original bond strength.

Methods: The KATANA AVENCIA block (Kuraray Noritake Dental) was sandblasted on the adherend surface (P-Co group). Then, the block was contaminated with artificial saliva (Saliveht Aerosol, Teijin). Air dry (N-Co), sandblasting (Sb) and phosphate acid cleaning (AT) groups were prepared. After silane treatment, PANAVIA V5 (Kuraray Noritake Dental) was built up and microtensile bond strength (mTBS) was measured after immersion in water (n = 24 per group). Scanning electron microscopy (SEM) analysis, surface roughness and contact angle measurement of each surface were performed.

Results: The P-Co group showed the highest mTBS value, and bond strength was significantly lower in the N-Co group than the other groups (P < 0.001). In all groups, decreased bond strength resulted from longterm water storage. In the N-Co group, a contaminated layer was observed on the surface by SEM and the contact angle was significantly smaller than the other groups (P < 0.001). In Sb and AT groups, mTBS values that were reduced by artificial saliva contamination significantly increased but did not recover to P-Co group values (P < 0.001). SEM showed no morphological difference between P-Co, Sb and AT groups. The Sb group showed increased surface roughness.

Conclusion: The long-term durability of bonds between CAD/CAM resin blocks and luting agent cement was significantly reduced by artificial saliva contamination. However, sandblasting or phosphoric acid cleaning can recover bonding effectiveness by 75–85%.

Purpose: The aim has been to determine the effect of thermo-mechanical cycling on shear-bond-strength (SBS) of dental porcelain to Co–Cr and Ti-based alloys fabricated by casting, computer-numerical- controlled milling, and selective-laser-melting (SLM).

Methods: Seven groups (n = 22/group) of metal cylinders were fabricated by casting (Co–Cr and commercially pure-cpTi), milling (Co–Cr, cpTi, Ti-6Al-4V) or by SLM (Co–Cr and Ti-6Al-4V) and abraded with airborne-particles. The average surface roughness (Ra) was determined for each group. Dental porcelain was applied and each metal–ceramic combination was divided into two subgroups — stored in deionized water (24-h, 37 °C), or subjected to both thermal (6000-cycles, between 5 and 60 °C) and mechanical cycling (105-cycles, 60 N-load). SBS test-values and failure modes were recorded. Metal– ceramic interfaces were analyzed with a focused-ion-beam/scanning-electron-microscope (FIB/SEM) and energy-dispersive-spectroscopy (EDS). The elastic properties of the respective metal and ceramic materials were evaluated by instrumented-indentation-testing. The oxide thickness on intact Ti-based substrates was measured with Auger-electron-spectroscopy (AES). Data were analyzed using ANOVA, Tukey's HSD and t-tests (a = 0.05).

Results: The SBS-means differed according to the metal–ceramic combination (p < 0.0005) and to the fatigue conditions (p < 0.0005). The failure modes and interface analyses suggest better porcelain adherence to Co–Cr than to Ti-based alloys. Values of Ra were dependent on the metal substrate (p < 0.0005). Ti-based substrates were not covered with thick oxide layers following digital fabrication.

Conclusions: Ti-based alloys are more susceptible than Co–Cr to reduction of porcelain bond strength following thermo-mechanical cycling. The porcelain bond strength to Ti-based alloys is affected by the applied metal processing technology.

Purpose: The aim of this study was to assemble and verify a measuring system for 3-D movements (attitude angle) of the denture during function.

Methods: For the calibration test, the sensor was fixed at the center of the rotary table. Operation and stopping of the rotary table were repeated 8 times, and the direction of rotation was reversed in the middle. The amount of rotation was 1.2 and 2.4°. As a pilot clinical trial, the attitude angles of three upper complete dentures during tapping were measured by this system.

Results: The attitude angles calculated by this system reduced by 3–4%. Pitch and roll of Subject III were significantly larger than Subjects I and II (P < 0.001), but yaw of Subject: III was significantly smaller than Subject: II (P < 0.01) during tapping. Pitch and yaw of "good" was significantly smaller than "average" in the stability of the dentures (P < 0.001). But roll of "average" was significantly smaller than "good" (P < 0.05). Pitch and yaw of "B" was significantly smaller than "C" in the type of maxillary ridge (P < 0.001). But roll of "C" was significantly smaller than "B" (P < 0.05).

Conclusions: The measurement accuracy of this system was equivalent to that of 3-D motion capture system by four infrared TV cameras. The measuring system using the IMU is reliable and easy to analyze the attitude angle of the denture during function. It may serve a diagnostic appliance to evaluate the quality of the denture.

Purpose: To compare the displacements of CAD–CAM zirconia and titanium abutments into different internal connection systems after torquing.

Methods: OsseoSpeed EV and OsseoSpeed TX implants (n = 10) were placed in resin blocks. Zirconia and titanium abutments (n = 5) were first hand tightened and then tightened to the recommended torque (20 N cm for TX and 25 N cm for EV). Displacements of abutments between screw tightening by hand and torque driver was measured using three-dimensional digital image correlation (3D DIC) technique. Displacements were measured in U (front/back), V (into/outward), W (right/left) directions and 3- dimensionally (3D). ANOVA with restricted maximum likelihood estimation method was used to analyze the data. Bonferroni-corrected t tests was used to determine the statistical differences (α = 0.05).

Results: 3D displacement of zirconia and titanium abutments was significantly greater in OsseoSpeed EV implant (P < 0.001). Displacement of zirconia and titanium abutments was not significantly different within implant systems, 3D (P ≥ 0.386) and in each direction (P ≥ 0.382). In U and V directions, zirconia and titanium abutments displaced significantly more towards negative in OsseoSpeed EV implant (P < 0.019). Within the OsseoSpeed TX system, abutments displaced significantly more in V direction compared to the U and W (P ≤ 0.005), and within the Osseospeed EV system, abutment displacements were significantly different amongst directions and displacements in V were the greatest (P < 0.001).

Conclusion: Abutments displaced more in the implant that required higher torque values to tighten the abutment. The amount of displacement in both systems was clinically small. Abutment material did not affect the magnitude of displacement.

Purpose: The purpose of the present study was to evaluate the effect of priming agents and artificial aging with thermocycling on shear bond strengths of two resin-based luting agents to a translucent zirconia material.

Methods: A total of 308 pairs of translucent zirconia disk specimens were divided into seven treatment groups: Alloy Primer (ALP), Clearfil Ceramic Primer Plus (CCP), Meta Fast Bonding Liner (MFB), MR. bond (MRB), Super-Bond PZ Primer Liquid B (PZB), V-Primer (VPR), and an unprimed group (UP). The specimens in each group were bonded with Panavia V5 Universal (UNI) and Opaque shade (OPA). Shear bond strengths (n = 11 each) were tested before and after 5000 thermocycles. The data were analyzed with the Kruskal–Wallis test and the Steel–Dwass test.

Results: For both 0 and 5000 thermocycles, the ALP (47.8 and 41.5 MPa, respectively) and CCP (45.8 and 42.3 MPa, respectively) groups showed significantly higher bond strengths than other groups in the UNI luting agent. For the OPA luting agent, CCP group (45.8 MPa) exhibited the highest pre-thermocycling bond strength in all groups. The ALP (32.4 MPa) and CCP (36.5 MPa) groups had significantly higher postthermocycling shear bond strengths than other groups. In several groups, the shear bond strengths of the UNI luting agent were significantly higher than those of the OPA luting agent before and after thermocycling.

Conclusions: Application of priming agents containing hydrophobic phosphate monomer (MDP) yielded the durable bond strengths of resin-based luting agents to a translucent zirconia material.

Purpose: This study evaluated the effect of surface treatment of zirconia in pre-sintered and post-sintered stages on its surface roughness, phase transformation, and biaxial flexural strength (BFS).

Methods: Zirconia ceramic discs (n = 40) having a final dimensions of 12 mm diameter and 1.2 mm thickness were milled then divided into three main groups according to the type of surface treatment performed (Group 1 (n = 16); air-abrasion using Al₂O₃ particles, Group 2 (n = 16); silica coating using Rocatec soft, and Group 3 (n = 8); a control group receiving no surface treatment). Groups 1 and 2 were divided into two subgroups each according to the stage in which the surface treatment was performed (Subgroup A; surface treatment performed in the pre-sintered stage and subgroup B; surface treatment performed in the post-sintered stage). Surface roughness, phase transformation, and biaxial flexural strength (BFS) were later assessed. Data was then analyzed using two-way ANOVA and Tukey post-hoc tests at a significance level of p ≤ 0.05.

Results: Subgroups treated in the pre-sintered stage showed higher mean Ra in μm (1.81 ± 0.36) when compared to the subgroups treated in the post-sintered (0.68 ± 0.07) stage and the control group (0.51 ± 0.10) (p ≤ 0.05). The pre-sintered treated group and the control showed no monoclinic phase while the post-sintered group showed significantly higher portions of monoclinic phase. Regarding BFS the post-sintered treated group had statistically significant higher values in MPa (1228 ± 81) when compared to the pre-sintered treated group (940 ± 101) and the control (1019 ± 82) (p ≤ 0.05).

Conclusions: Air abrasion in the pre-sintered stage might be a promising surface treatment method to produce promising surface roughness values of zirconia without subjecting it to early degradation.

PurposeTo evaluate the influence of fabrication method and finish line design on marginal and internal fit of full-coverage interim restorations.

MethodsFour typodont models of maxillary central-incisor were prepared for full-coverage restorations. Four groups were defined; knife-edge (KE), chamfer (C), rounded-shoulder (RS), rounded-shoulder with bevel (RSB). All preparations were digitally scanned. A total of 80 restorations were fabricated; 20 per group (SLA/3D-printed n = 10, milled n = 10). All restorations were positioned on the master die and scanned using micro-computed tomography. The mean gaps were measured digitally (ImageJ). The results were compared using MANOVA (α =.05).

ResultsInternal and marginal gaps were significantly influenced by fabrication method (P =.000) and finish-line design (P =.000). 3D-Printed restorations showed statistically significant lower mean gap compared to milled restorations at all points (P =.000). The mean internal gap for 3D-printed restorations were 66, 149, 130, 95 μm and for milled restorations were 89, 177, 185, 154 μm for KE, C, RS, RSB respectively. The mean absolute marginal discrepancy in 3D-printed restorations were (30, 41, 30, 28 μm) and in milled restorations were (56, 54, 52, 38 μm) for KE, C, RS, RSB respectively.

ConclusionsThe fabrication methods showed more of an influence on the fit compared to the effect of the finish-line design in both milled and printed restorations. SLA-printed interim restorations exhibit lower marginal and internal gap than milled restorations. Nonetheless, for both techniques, all values were within the reported values for CAD/CAM restorations.

Significance3D-printing can offer an alternative fabrication method comparable to those of milled restorations.

Purpose: To investigate stress and strain concentrations on resin-bonded fixed dental prostheses (RBFDPs) frameworks of different design using finite element analysis.

Methods: A human dry skull was scanned and models were produced using three-dimensional printer. After abutment preparation, three frameworks, including a three-unit RBFDP, and two-unit cantilevered RBFDPs using #21 and #23 for the abutment tooth, were fabricated. Scanned data were subtracted to define boundary of each structure. Occlusal force (200 N) was loaded at 45° to long axis of the pontic. The distributions of shear stress and principal strain in the RBFDP models were measured to evaluate the risk for framework-debonding from the abutment teeth and the impact on periodontal tissue.

Results: The percentage voxels with shear stress >11 MPa in adhesive cement layer of three-unit RBFDP using #21 and #23 were 4.16% and 2.25%, respectively; in two-unit cantilevered RBFDPs, it was 19.25% using #21, and 23.4% using #23. The maximum principal strain on periodontal ligaments in two-unit cantilevered RBFDPs using #21 was the largest, and smallest in the three-unit RBFDP. The maximum principal strain in framework was largest in the two-unit cantilevered RBFDP using #23, and smallest in the three-unit RBFDP.

Conclusions: The risk for framework-debonding in three-unit RBFDPs was substantially lower than that in two-unit RBFDPs. In difficult cases with indication for three-unit RBFDPs, two-unit cantilever design using the canine would be more advantageous for preservation of periodontal tissue, while for risk of framework-debonding, the design using the central incisor would be more advantageous.

Purpose: To provide a scientific data related to the tonic activity of masseter muscle in subjects with and without history of orofacial pain during their normal daily life.

Methods: Thirty-three subjects were divided into two groups, a pain history group (PHG) and a non-pain history group (non-PHG), based on their responses to the Research Diagnostic Criteria for Temporomandibular Disorders questionnaire. After excluding four subjects with incomplete recordings, full-day masseter muscle surface EMGs of 29 subjects (10 men, 19 women; mean age 24.1 years) were analyzed. Tonic episode (TE) was defined as continuous EMG activity with a duration at least 2 s with intensities above twice the baseline noise level. TEs were classified into 6 strength categories (<7.5%, 7.5–10%, 10–15%, 15–25%, 25–40% and >40% of the maximum voluntary clenching (MVC) ). The mean duration of activity observed in the non-PHG + 2 SD was adopted as a cutoff for identifying sustained TE.

Results: During waking hours, the incidence of sustained TEs was significantly higher in the PHG than in the non-PHG (p < 0.05). The incidence and total duration of sustained TEs were significantly higher in the PHG than in the non-PHG at intensities of 7.5–10% MVC, 10–15% MVC, and 15–25% MVC (p < 0.05). No significant difference was observed during sleep.

Conclusions: Within the limitations of this study, it would be concluded that sustained TEs may have a correlation with orofacial pain and the intensity range of 7.5–25% MVC would be an important range for future clenching studies

Purpose: Many patients with oromandibular dystonia, which is characterized by involuntary masticatory, lower facial, and/or tongue muscle contractions, experience relief of symptoms through sensory tricks such as eating chewing gum or candy. The aim of this study was to identify the factors influencing the effects of splints in patients with oromandibular dystonia.

Methods: Occlusal splints were inserted in 128 patients (89 women, 39 men) with oromandibular dystonia (102 with jaw closing dystonia, 20 with lingual dystonia, 5 with jaw deviation dystonia, 4 with jaw opening dystonia, 3 with lip dystonia, and 2 with jaw protrusion dystonia). Patients who showed improvement with the use of splints and continued to wear them for at least 3 months were defined as responders. In contrast, patients who showed little or no effect and/or were unable to insert splints were defined as non-responders. Differences in demographic and clinical data were statistically compared between responders and non-responders.

Results: Ninety-eight patients (76.6%) were responders (subjective improvement: 30.5%). Thirty patients (23.4%) were non-responders (subjective improvement: 7.2%). The responders were significantly older than the non-responders (53.8 years vs 47.0 years; p < 0.05). Patients with jaw closing dystonia showed the most favorable results. The proportion of patients with sensory tricks was significantly higher in responders than in non-responders (66.3% vs 26.7%; p < 0.05).

Conclusions: The sensory trick splint is especially helpful for patients with jaw closing dystonia. It is useful, although partially effective, as an alternative therapy in patients for whom other therapies have been unsatisfactory.

Purpose: An accurate impression is required for implant treatment. The aim of this in-vitro study was to determine the effect size of the impression material/method, implant system and implant angulation on impression transfer precision.

Methods: An upper jaw model with three BEGO and three Straumann implants (angulations 0°, 15°, 20°) in the left and right maxilla was used as a reference model. One polyether (Impregum Penta) and two polyvinyl siloxanes (Flexitime Monophase/Aquasil Ultra Monophase) were examined with two impression techniques (open and closed tray). A total of 60 impressions were made. A coordinate measurement machine was used to measure the target variables for 3D-shift, implant axis inclination and implant axis rotation. All the data were subjected to a four-way ANOVA. The effect size (partial etasquared [η²_P]) was reported.

Results: The impression material had a significant influence on the 3D shift and the implant axis inclination deviation (p-values =.000), and both factors had very large effect sizes (3D-shift [η²_P] =.599; implant axis inclination [η²_P] =.298). Impressions made with polyvinyl siloxane exhibited the highest transfer precision. When the angulation of the implants was larger, more deviations occurred for the implant axis rotational deviation. The implant systems and impression methods showed partially significant variations (p-values =.001–.639) but only very small effect sizes (η²_P =.001–.031).

Conclusions: The impression material had the greatest effect size on accuracy in terms of the 3D shift and the implant axis inclination. For multiunit restorations with disparallel implants, polyvinyl siloxane materials should be considered. In addition, the effect size of a multivariate investigation should be reported.

Purpose: High wear resistance of denture teeth preserves good occlusal relationship and sufficient parafunctional stability. This in-vitro investigation aimed to determine and compare the wear performance of different artificial denture teeth.

Methods: Denture teeth of fifteen commercial products (n = 8/group) were loaded in a pin-on-block design using steatite antagonists (d = 3 mm). Cyclic loading (50 N) was applied for 120,000 loadings (ƒ = 1.2 Hz) with simultaneous thermal cycling (distilled water, 5 °C/55 °C, 2 min/cycle). A loading cycle consisted of a vertical 1 mm impact and a subsequent lateral 1 mm sliding movement. Worn areas were digitalized (3-D-laser-scanning-microscope). Maximum and mean wear depth and surface roughness were determined and statistically compared (one-way Anova, Tukey-HSD test, a = 0.05). Worn surfaces and cut specimens were investigated with scanning electron microscopy (SEM).

Results: Maximum wear varied between 475.1 μm and 1232.2 μm. Mean wear was between 241.1 μm and 753.6 μm with significant differences (p < 0.001) between individual materials. Mean and maximum wear showed a significant correlation (Pearson's correlation coefficient: 0.942). Surface roughness increased between unworn to worn surface by 1.2 mm (Ra, p = 0.387) and by 41.7 μm (Rz, p = 0.000). All materials provided round or drop-shaped wear traces. Superficial analysis showed no cracks, chipping or fractures in the worn areas. Detailed evaluation of cut specimens with SEM exposed cracks on the bottom of the wear traces.

Conclusions: Denture teeth showed significantly different in-vitro wear performance and increased roughness in the wear trace. Differences may be attributed to the composition of the materials, regarding both filler and polymer structure. The selection of teeth might contribute to enhanced in-vivo performance of the denture.

Purpose: The aims were to analyze stiffness, ultimate force, and failure modes of a 2-piece zirconium dioxide (ZrO2) implant system.

Methods: Eleven 2-piece ZrO₂ implants, each mounted with ZrO₂ abutments plus bonded monolithic lithium disilicate (LS₂) restorations, were grouped for 3.3 mm (A) and 4.1 mm (B) diameter samples. Quasi-static load was monotonically applied under a standardized test set-up (loading configuration according to DIN ISO 14801). The ultimate force was defined as the maximum force that implants are able to carry out until fracture; stiffness was measured as the maximum slope during loading. An unpaired ttest was performed between group A and B for ultimate force and stiffness (p < 0.05).

Results: Force-displacement curves revealed statistically homogenous inner-group results for all samples. Failure modes showed characteristic fractures at the neck configuration of the implants independent of the diameter. Mean stiffness was 1099 N/mm (± 192) for group A, and significantly lower compared to group B with 1630 N/mm (± 274) (p < 0.01); whereas mean ultimate force was 348 N (± 53) for group A, and significantly increased for group B with 684 N (± 29) (p < 0.0001).

Conclusions: The examined 2-piece ZrO₂ implant system mounted to LS₂-restorations seems to be a stable unit under in-vitro conditions with mechanical properties compared to loading capacity of physiological force. The metal-free implant reconstructions demonstrated high stiffness and ultimate force under quasi-static load for single tooth replacement under consideration of the dental indication of narrow and standard diameter implants.

Purpose: The goal of this work is to describe an implant-prosthetic protocol for rehabilitation of edentulous mandible, by using a fixed prosthesis made of fiber-reinforced composite material (FRC). The protocol contemplates a minimal invasive surgery and ensures predictable and safe results, with good aesthetic and performance combined to cost savings.

Methods: FRC material is used to build the substructure of a prosthetic framework supported by four short implants (5 mm long and 4 mm wide). The prosthesis substructure is made of Trinia immersed in a matrix of epoxy resin (FRC). It is supplied in milling blocks (pre-cured) for the CAD/CAM (computer-aided design/computer-aided manufacturing) technique.

Implants are placed in lower edentulous jaw in position of first molar and canine, each side. Four month after, a resin bar is build based on a stone model, denture teeth are placed and the occlusion is checked. The resin bar and the stone model with milled abutments are scanned and a FRC bar is achieved with the CAD/CAM technique. The teeth are mounted to the substructure trough denture resin. Temporary cementation of framework is achieved on the abutments connected to the implants.

Conclusion: A protocol for a fixed mandibular implant-prosthetic rehabilitation is described. The protocol contemplates a minimal invasive surgery and ensures predictable and safe results, with good aesthetic and performance combined to cost savings. In addition, this technique allows performing basic surgery also in presence of atrophy.

Patients: High or excessive parafunctional jaw muscle activity is a frequent complication of acquired braininjury (ABI) and may have some similarities to bruxism. Bruxism has been associated with increased tooth wear, masseter hypertrophy and headaches. The aim of this observational study was to identify the levels of jaw muscle activity from fourteen ABI patients having different functional and cognitive levels in their early phase of neurological rehabilitation (according to their Ranchos Los Amigos Scale (RLAS) score). Nine patients were severely cognitive impairement (RLAS score 1–3): with no or little response to any external stimuli due to low arousal and five patients were with RLAS score 4–8: depending on responses to stimuli and confusion level i.e. defining that patients had enough arousal to respond and react and therefore were able to follow the instructions. A single-channel electromyographic (EMG) device was used to assess the jaw muscle EMG activity in ABI patients for two hours continuously at two different days.

Discussion: The mean (± SD) jaw muscle activity observed in patients with ABI was 46.9 ± 6.5 EMG events/h with a wide range between 1–163 EMG events/h but with no significant difference between days (P = 0.230).

Conclusion: Irrespective of functional and cognitive ability scores patients with ABI had a wide range of EMG activity. The use of ambulatory single-channel EMG devices might open a path for further studies to determine levels of jaw muscle activity associated with potential side effects in ABI patients.