Transcutaneous auricular vagus nerve stimulation for the treatment of myoarthropatic symptoms in patients with craniomandibular dysfunction - a protocol for a randomized and controlled pilot trial.

BACKGROUND: Temporomandibular disorders (TMD) are a collective term for pain and dysfunction of the masticatory muscles and the temporomandibular joints. The most common types of TMD are pain-related, which may impact the psychological behavior and quality of life. Currently, the most popular methods for the treatment of TMD patients are occlusal splint therapy, often in combination with physical- and/or pharmacotherapy. However, due to the complexity of etiology, the treatment of chronic TMD remains a challenge. Recently, CE-certified systems for non-invasive VNS (transcutaneous auricular vagus nerve stimulation, taVNS) have become available and show positive effects in the treatment of chronic pain conditions, like migraine or fibromyalgia, with which TMD shares similarities. Therefore, it is the main purpose of the study to evaluate the feasibility of daily taVNS against chronic TMD and to assess whether there is an improvement in pain severity, quality of life, and kinetic parameters. METHODS: This study is designed as a single-blinded, double-arm randomized controlled trial (RCT) in a 1:1 allocation ratio. Twenty adult patients with chronical TMD symptoms will be enrolled and randomized to stimulation or sham group. In the stimulation group, taVNS is performed on the left tragus (25 Hz, pulse width 250 µs, 28 s on/32 s off, 4 h/day). The sham group will receive no stimulation via a non-functional identical-looking electrode. Validated questionnaire data and clinical parameters will be collected at the beginning of the study and after 4 and 8 weeks. The compliance of a daily taVNS of patients with chronical TMD will be evaluated via a smartphone app recording daily stimulation time and average intensity. Additionally, the treatment impact on pain severity and quality of life will be assessed with different questionnaires, and the effect on the mandibular mobility and muscle activity will be analyzed. DISCUSSION: This is the first clinical trial to assess the feasibility of taVNS in patients with chronic TMD symptoms. If taVNS improves the symptoms of TMD, it will be a significant gain in quality of life for these chronic pain patients. The results of this pilot study will help to determine the feasibility of a large-scale RCT. TRIAL REGISTRATION: This study has been registered in the DRKS database (DRKS00029724).

Influence of ceramic thickness and dental substrate on the survival rate and failure load of non-retentive occlusal veneers after fatigue.

OBJECTIVE: To investigate the effect of ceramic thickness and dental substrate (enamel vs. dentin/enamel) on the survival rate and failure load of non-retentive occlusal veneers. MATERIALS AND METHODS: Human maxillary molars (n = 60) were divided into five test-groups (n = 12). The groups (named DE-1.5, DE-1.0, DE-0.5, E-1.0, E-0.5) differed in their dental substrate (E = enamel, DE = dentin/enamel) and restoration thickness (standard: 1.5 mm, thin: 1.0 mm, ultrathin: 0.5 mm). All teeth were prepared for non-retentive monolithic lithium-disilicate occlusal veneers (IPS e.max Press, Ivoclar). Restorations were adhesively cemented (Syntac Classic/Variolink II, Ivoclar) and exposed to thermomechanical fatigue (1.2 million cycles, 1.6 Hz, 49 N/ 5-55°C). Single load to failure was performed using a universal testing-machine. A linear-regression model was applied, pairwise comparisons used the Student-Newman-Keuls method (p < 0.05). RESULTS: Three dentin-based occlusal veneers (one DE-1.0, two DE-0.5) revealed cracks after fatigue exposure, which corresponds to an overall-survival rate of 95%. Load to failure resulted in the following ranking: 2142 N(DE-0.5) > 2105 N(E-1.0) > 2075 N(E-0.5) > 1440 N(DE-1.5) > 1430 N(DE-1.0). Thin (E-1.0) and ultrathin enamel-based occlusal veneers (E-0.5) revealed high failure loads and surpassed the standard thickness dentin-based veneers (DE-1.5) significantly (p = 0.044, p = 0.022). CONCLUSION: All tested monolithic lithium disilicate occlusal veneers obtained failure loads above physiological chewing forces. Thin and ultrathin enamel-based occlusal veneers outperformed the standard thick dentin-based occlusal veneers. CLINICAL SIGNIFICANCE: Minimally invasive enamel-based occlusal veneer restorations with non-retentive preparation design may serve as a conservative treatment option.

Reliability and Failure Mode of Ti-Base Abutments Supported by Narrow/Wide Implant Systems.

To assess the reliability and failure modes of Ti-base abutments supported by narrow and wide-diameter implant systems. Narrow (Ø3.5 × 10 mm) and wide (Ø5 × 10 mm) implant systems of two different manufacturers with internal conical connections (16°) and their respective Ti-base abutments (3.5 and 4.5 mm) were evaluated. Ti-base abutments were torqued to the implants, standardized metallic maxillary incisor crowns were cemented, and step stress accelerated life testing of eighteen assemblies per group was performed in three loading profiles: mild, moderate, and aggressive until fracture or suspension. Reliability for missions of 100,000 cycles at 100 and 150 N was calculated, and fractographic analysis was performed. For missions at 100 N for 100,000 cycles, both narrow and wide implant systems exhibited a high probability of survival (≥99%, CI: 94-100%) without significant differences. At 150 N, wide-diameter implants presented higher reliability (≥99%, CI: 99-100%) compared to narrow implants (86%, CI: 61-95%), with no significant differences among manufacturers. Failure mode predominantly involved Ti-base abutment fractures at the abutment platform. Ti-base abutments supported by narrow and wide implant systems presented high reliability for physiologic masticatory forces, whereas for high load-bearing applications, wide-diameter implants presented increased reliability. Failures were confined to abutment fractures.

Failure Load and Fatigue Behavior of Monolithic and Bi-Layer Zirconia Fixed Dental Prostheses Bonded to One-Piece Zirconia Implants.

No evidence-based prosthetic treatment concept for 3-unit fixed-dental-prostheses (FDPs) on ceramic implants is currently available. Therefore, the aim of this in vitro study was to investigate the failure load and fatigue behavior of monolithic and bi-layer zirconia FDPs supported by one-piece ceramic implants. Eighty 3-unit FDPs supported by 160 zirconia-implants (ceramic.implant; vitaclinical) were divided into 4 groups (n = 20 each): Group Z-HT: 3Y-TZP monolithic-zirconia (Vita-YZ-HT); Group Z-ST: 4Y-TZP monolithic-zirconia (Vita-YZ-ST); Group FL: 3Y-TZP zirconia (Vita-YZ-HT) with facial-veneer (Vita-VM9); Group RL (Rapid-layer): PICN "table-top" (Vita-Enamic), 3Y-TZP-framework (Vita-YZ-HT). Half of the test samples (n = 10/group) were fatigued in a mouth-motion chewing-simulator (F = 98 N, 1.2 million-cycles) with simultaneous thermocycling (5−55 °C). All specimens (fatigued and non-fatigued) were afterwards exposed to single-load-to-failure-testing (Z010, Zwick). Statistical analysis was performed using ANOVA, Tukey's post-hoc tests and two-sample t-tests (p < 0.05, Bonferroni-corrected where appropriate). All specimens withstood fatigue application. While the effect of fatigue was not significant in any group (p = 0.714), the choice of material had a significant effect (p < 0.001). Material FL recorded the highest failure loads, followed by Z-ST, Z-HT and RL, both with and without fatigue application. Taken together, all tested FDP material combinations survived chewing forces that exceeded physiological levels. Bi-Layer FL and monolithic Z-ST showed the highest resilience and might serve as reliable prosthetic reconstruction concepts for 3-unit FDPs on ceramic implants.

Posterior minimally invasive full-veneers: Effect of ceramic thicknesses, bonding substrate, and preparation designs on failure-load and -mode after fatigue.

OBJECTIVE: To evaluate the effect of ceramic thicknesses, bonding surface (enamel vs. dentin), and preparation design (box vs. no box) on the fatigue survival and failure load of minimally invasive full-veneer restorations. MATERIALS AND METHODS: Human-premolars (n = 60) were divided into five test groups (n = 12). All teeth received full-veneer preparation with the following occlusal/labial thicknesses: standard: 1.5/0.8 mm; thin: 1.0/0.6 mm; ultrathin 0.5/0.4 mm. Preparations for each ceramic thickness were refined in enamel (E-1.0 and E-0.5) or dentin (D-1.5, D-1.0, and D-0.5). Control groups DB-1.5, EB-1.0, and EB-0.5 received box preparations. Monolithic lithium disilicate restorations (IPS-e.max-Press, Ivoclar Vivadent) were adhesively cemented (Syntac-Classic/Variolink-II, Ivoclar Vivadent) and subjected to cyclic mechanical loading (F = 49 N, 1.2 million cycles) with simultaneous thermocycling (5-55°C). All specimens were exposed to single load-to-failure. Pair-wise differences were calculated by using a linear regression model and Student-Newman-Keuls method (p < 0.05). RESULTS: All full-veneers of group D-1.5, E-1.0, E-0.5, DB-1.5, EB-1.0, and EB-0.5 survived fatigue. Two full-veneers (D-1.0 and D-0.5) revealed cracks during fatigue, resulting in an overall fatigue survival rate of 98.1%. Mean load-to-failure values (N) were as followed: 1005 (D-1.5); 866 (D-1.0); 816 (D-0.5); 1495 (E-1.0); 1279 (E-0.5); 1129 (DB-1.5); 1087 (EB-1.0); and 833 (EB-0.5). Irrespective of ceramic thicknesses, enamel-based full-veneers resulted in higher failure loads than dentin-based restorations. Box preparation reduced the failure loads of thin and ultrathin enamel-based restorations. CONCLUSION: All tested monolithic lithium disilicate full-veneer restorations exceeded physiological masticatory forces. Minimally invasive full-veneer restorations with enamel as a bonding surface and a non-retentive preparation design showed superior performance. CLINICAL SIGNIFICANCE: Enamel-based non-retentive full-veneers made of monolithic lithium disilicate may serve as a reliable and esthetical minimally invasive treatment option for premolars.

Mechanical Stability of Screw-Retained Monolithic and Bi-layer Posterior Hybrid Abutment Crowns after Thermomechanical Loading: An In Vitro Study.

To evaluate the failure-load and survival-rate of screw-retained monolithic and bi-layered crowns bonded to titanium-bases before and after mouth-motion fatigue, 72 titanium-implants (SICvantage-max, SIC-invent-AG) were restored with three groups (n = 24) of screw-retained CAD/CAM implant-supported-single-crowns (ISSC) bonded to titanium-bases: porcelain-fused-to-metal (PFM-control), porcelain-fused-to-zirconia (PFZ-test) and monolithic LDS (LDS-test). Half of the specimens (n = 12/group) were subjected to fatigue in a chewing-simulator (1.2 million cycles, 198 N, 1.67 Hz, thermocycling 5-55 °C). All samples were exposed to single-load-to-failure without (PFM0, PFZ0, LDS0) or with fatigue (PFM1, PFZ1, LDS1). Comparisons were statistically analyzed with t-tests and regression-models and corrected for multiple-testing using the Student-Neuman-Keuls method. All PFM and LDS crowns survived fatigue exposure, whereas 16.7% of PFZ showed chipping failures. The mean failure-loads (±SD) were: PFM0: 2633 ± 389 N, PFM1: 2349 ± 578 N, PFZ0: 2152 ± 572 N, PFZ1: 1686 ± 691 N, LDS0: 2981 ± 798 N, LDS1: 2722 ± 497 N. Fatigue did not influence load to failure of any group. PFZ ISSC showed significantly lower failure-loads than monolithic-LDS regardless of artificial aging (p < 0.05). PFM ISSC showed significantly higher failure loads after fatigue than PFZ (p = 0.032). All ISSC failed in a range above physiological chewing forces. Premature chipping fractures might occur in PFZ ISSC. Monolithic-LDS ISSC showed high reliability as an all-ceramic material for screw-retained posterior hybrid-abutment-crowns.

Fabrication, workflow and delivery of reconstruction: Summary and consensus statements of group 4. The 6th EAO Consensus Conference 2021.

OBJECTIVES: To report assessments of four systematic reviews (SRs) on (i) clinical outcomes of all-ceramic implant-supported crowns (iSCs), (ii) production time, effectiveness, and costs of computer-assisted manufacturing (CAM), (iii) computer-assisted implant planning and surgery (CAIPS) time and costs, and (iv) patient-reported outcome measures (PROMS). MATERIAL AND METHODS: An author group consisting of experienced clinicians and content experts discussed and evaluated the SRs and formulated consensus on the main findings, statements, clinical recommendations, and need for future research. RESULTS: All four SRs were conducted and reported according to PRISMA and detailed comprehensive search strategies in at least three bibliometric databases and hand searching. The search strategies were deemed reproducible. Variation was noted regarding language restrictions and inclusion of grey literature, but the search comprehensiveness appeared persuasive. The SRs included bias risk assessments of the primary studies, and their study methodology impacted the interpretations of the extracted data. CONCLUSIONS: (i) There is limited evidence (49 NRCT) showing that veneered and monolithic all-ceramic iSCs have excellent outcomes observed up to 3 years. (ii) There is no evidence evaluating production time and effectiveness comparing subtractive and additive CAM of implant models, abutments and crowns. (iii) There is limited evidence (4 RCT) that CAIPS involves more time and costs when considering the entire workflow and for diagnostics, manufacturing, and insertion of the restoration. Time seems to be the decisive factor for higher costs. (iv) Patients' comfort increases when optical compared to conventional impressions are used for fabricating iSCs and short-span FPDs (2 RCT, 5 NRCT).

Failure Load and Fatigue Behavior of Monolithic Translucent Zirconia, PICN and Rapid-Layer Posterior Single Crowns on Zirconia Implants.

This laboratory study aimed to evaluate the thermo-mechanical fatigue behavior and failure modes of monolithic and rapid-layer posterior single-crowns (SCs) supported by zirconia implants. METHODS: 120 all-ceramic crowns supported by one-piece zirconia implants (ceramic.implant; vitaclinical) were divided into five groups (n = 24 each): Group Z-HT: 3Y-TZP monolithic-zirconia (Vita-YZ-HT); Group Z-ST: 4Y-TZP monolithic-zirconia (Vita-YZ-ST); Z-XT: 5Y-TZP monolithic-zirconia (Vita-YZ-XT); Group E: monolithic-polymer-infiltrated ceramic network (PICN,Vita-Enamic); Group RL (rapid layer): PICN-"table-top" (Vita-Enamic), 3Y-TZP-framework (Vita-YZ-HT). Half of the specimens of each group (n = 12) were exposed to fatigue with cyclic mechanical loading (F = 198N, 1.2-million cycles) and simultaneous thermocycling (5-55 °C). Single-load-to-failure testing (Z010, Zwick) was performed for all specimens without/with fatigue application. Data analysis was performed using ANOVA, Tukey's post-hoc test, two-sample t-test and Bonferroni correction (p < 0.05). RESULTS: All specimens survived fatigue exposure. Significant differences in failure loads were detected among groups (p ≤ 0.004). Materials Z-HT and Z-ST showed the highest failure loads followed by Z-XT, RL and E. The influence of fatigue was only significant for material RL. CONCLUSIONS: All types of tested materials exceeded clinically acceptable failure load values higher than 900N and can be recommended for clinical use. Z-HT and Z-ST appear to be highly reliable towards fatigue. Rapid-layer design of PICN and YZ-HT might be an interesting treatment concept for posterior implant SCs.

Monolithic Screw-Retained Lithium Disilicate Implant Crowns: Preliminary Data of a Prospective Cohort Study.

PURPOSE: To analyze the clinical behavior of screw-retained monolithic lithium disilicate (LDS) implant-supported single crowns (ISSCs) over a 1-year follow-up. MATERIALS AND METHODS: A total of 28 patients were restored with 45 screw-retained monolithic LDS (press-fabricated) ISSCs bonded to titanium bases in posterior sites. Modified United States Public Health Service criteria and Kaplan-Meier survival and success rates were evaluated. RESULTS: A total of 27 patients with 44 ISSCs were evaluated 12 months (mean ± standard deviation: 13.02 ± 2.28) after prosthesis delivery. No implant or crown failures occurred. The Kaplan-Meier survival and success rates were each 100% after 1 year. Minorly increased surface roughness was noted in the occlusal contact point areas of 9 ISSCs (20.5% Bravo rating). Marginal adaptation, color match, and anatomical form stayed favorable over time. CONCLUSION: Press-fabricated LDS monolithic screw-retained implant crowns appear to be a promising treatment option for posterior implants under short-term observation.

Monolithic Polymer-Infiltrated Ceramic Network CAD/CAM Single Crowns: Three-Year Mid-Term Results of a Prospective Clinical Study.

PURPOSE: To evaluate the clinical outcomes of monolithic CAD/CAM-fabricated polymer-infiltrated ceramic network (PICN) single crowns (SC) after 3 years. MATERIALS AND METHODS: A total of 34 patients who received 76 single crowns were included in this cohort study. Full-coverage crown preparation with reduced thickness (1.0 to 1.5 mm) was applied. All monolithic PICN SCs (VITA Enamic) were manufactured using a CAD/CAM system and adhesively seated. Clinical follow-up evaluations were performed at 6, 12, 24, and 36 months after insertion using modified United States Public Health Service (USPHS) criteria. Kaplan-Meier survival and success methods were applied to calculate absolute and relative failures. To determine effects of time and restoration, a mixed logit model was adjusted for the modified USPHS criteria (P < .05). RESULTS: PICN SCs revealed an estimated Kaplan-Meier survival rate of 93.9% after 3 years. Four clinically unacceptable fractures occurred, which resulted in replacement of the affected SCs. Neither secondary caries nor debonding were recorded. The 3-year Kaplan-Meier success rate was 92.7%. Significant increases in marginal discoloration (P = .0002) and surface roughness (P < .0001) were noted over time. Color match, anatomical form, and marginal adaptation remained favorable over the given observation period. CONCLUSION: PICN CAD/CAM crowns with reduced thickness showed acceptable survival and success rates over a service time of 36 months. However, extended clinical follow-up periods are needed to evaluate the long-term performance.

Prosthetic protocols in implant-based oral rehabilitations: A systematic review on the clinical outcome of monolithic all-ceramic single- and multi-unit prostheses.

AIM: The purpose of this systematic review was to assess the clinical performance of implant-supported monolithic all-ceramic single- and multi-unit restorations. MATERIALS AND METHODS: The electronic databases of MEDLINE via PubMed, the Cochrane Library (CENTRAL) and EMBASE were searched for clinical studies on monolithic all-ceramic single and multi-unit implant-supported fixed dental prostheses. Human studies with a mean follow-up of at least 2 years and published in English or German language peer-reviewed journals up until August 2016 were included. Two independent examiners conducted the literature search and review process. RESULTS: The search resulted in 2510 titles and of these, 57 studies were selected for full-text evaluation. Three studies were included on the basis of the pre-determined criteria. Two articles reported on monolithic lithium disilicate implant-supported single crowns (SC) and revealed a survival rate of 97,8 and 100% after 3 years. One study investigated implant- supported monolithic zirconia SCs and fixed partial dentures (FPD) and showed a survival rate of 100% after 5 years. No studies could be identified on the clinical performance of monolithic resin matrix ceramic restorations. Clinical studies are lacking on the long-term outcome of implant-supported monolithic all-ceramic single- and multi-unit restorations. CONCLUSIONS: Preliminary clinical data indicate high short-term survival for implant-supported monolithic lithium disilicate and zirconia single- and multi-unit restorations. Randomised clinical studies and observations with a longer duration are necessary to validate the broad application of this therapy. Conflict-of-interest statement: The authors declare no conflict of interest.

Adhesive Bonding to Hybrid Materials: An Overview of Materials and Recommendations.

Recently, hybrid materials have been introduced to the dental market. Together with computer-assisted design/computer-assisted manufacturing (CAD/CAM) composite resins, they form a new class of dental CAD/CAM materials that combine the positive effects of ceramics and composites. As bonding is essential for their clinical longevity, it is crucial to have a good understanding of their material properties and cementation protocols. This review offers clinicians an overview of available hybrid materials and recommendations for their respective adhesive placements.

Resin bond to indirect composite and new ceramic/polymer materials: a review of the literature.

STATEMENT OF THE PROBLEM: Resin bonding is essential for clinical longevity of indirect restorations. Especially in light of the increasing popularity of computer-aided design/computer-aided manufacturing-fabricated indirect restorations, there is a need to assess optimal bonding protocols for new ceramic/polymer materials and indirect composites. PURPOSE OF THE STUDY: The aim of this article was to review and assess the current scientific evidence on the resin bond to indirect composite and new ceramic/polymer materials. MATERIALS AND METHODS: An electronic PubMed database search was conducted from 1966 to September 2013 for in vitro studies pertaining the resin bond to indirect composite and new ceramic/polymer materials. RESULTS: The search revealed 198 titles. Full-text screening was carried out for 43 studies, yielding 18 relevant articles that complied with inclusion criteria. No relevant studies could be identified regarding new ceramic/polymer materials. Most common surface treatments are aluminum-oxide air-abrasion, silane treatment, and hydrofluoric acid-etching for indirect composite restoration. Self-adhesive cements achieve lower bond strengths in comparison with etch-and-rinse systems. Thermocycling has a greater impact on bonding behavior than water storage. CONCLUSIONS: Air-particle abrasion and additional silane treatment should be applied to enhance the resin bond to laboratory-processed composites. However, there is an urgent need for in vitro studies that evaluate the bond strength to new ceramic/polymer materials. CLINICAL SIGNIFICANCE: This article reviews the available dental literature on resin bond of laboratory composites and gives scientifically based guidance for their successful placement. Furthermore, this review demonstrated that future research for new ceramic/polymer materials is required.