Crowns

BackgroundThis Finite Element Analysis was conducted to analyze the biomechanical behaviors of titanium base abutments and several crown materials with respect to fatigue lifetime and stress distribution in implants and prosthetic components.MethodsFive distinct designs of implant-supported single crowns were modeled, including a polyetheretherketone (PEEK), polymer-infiltrated ceramic network, monolithic lithium disilicate, and precrystallized and crystallized zirconia-reinforced lithium silicates supported by a titanium base abutment. For the static load, a 100 N oblique load was applied to the buccal incline of the palatal cusp of the maxillary right first premolar. The dynamic load was applied in the same way as in static loading with a frequency of 1 Hz. The principal stresses in the peripheral bone as well as the von Mises stresses and fatigue strength of the implants, abutments, prosthetic screws, and crowns were assessed.ResultsAll of the models had comparable von Mises stress values from the implants and abutments, as well as comparable maximum and minimum principal stress values from the cortical and trabecular bones. The PEEK crown showed the lowest stress (46.89 MPa) in the cervical region. The prosthetic screws and implants exhibited the highest von Mises stress among the models. The lithium disilicate crown model had approximately 9.5 times more cycles to fatique values for implants and 1.7 times more cycles to fatique values for abutments than for the lowest ones.ConclusionsWith the promise of at least ten years of clinical success and favorable stress distributions in implants and prosthetic components, clinicians can suggest using an implant-supported lithium disilicate crown with a titanium base abutment.

BackgroundPediatric dental treatment is challenging in patients with early childhood caries. For clinician its difficult to manage child and provide good work at the same time. Its necessity to have the best equipments as well as materials. Nowadays, aesthetics play an important role in managing decayed teeth. Zirconia crown is better option but requires excessive preparation. As Bioflx is newly developed crown and has combined stainless steel and zirconia properties.AimTo assess the clinical performance and child and parental satisfaction of Bioflex crowns compared to zirconia and stainless steel crowns.MethodsIn this comparative study of Bioflx crowns with zirconia and stainless steel crowns, children aged three to seven years old will be selected, and 72 primary teeth requiring crowns will be randomly distributed into three groups, n = 24: Group I: Preformed stainless steel crown, control; Group II: Preformed Bioflex crown; Group III: Preformed zirconia crown. Crowns will be evaluated for recurrent caries, plaque accumulation, restoration failure, gingival status opposing tooth wear, and clinicians and parental satisfaction at zero, three, six, and 12 months.ResultsBioflx crown will have better clinical as well as parental satisfaction among zirconia and stainless steel crowns.ConclusionsThe Bioflx crown can be used as an alternative economical esthetic full-coronal restoration for primary teeth.Trial registrationCTRI registration number: CTRI/2023/05/052256; Date of registration: May 03, 2023.Protocol versionTwo; Date: April 22, 2023.

AimTo evaluate the 3-year clinical and radiographic outcomes of implant-supported restorations with different emergence profiles (CONVEX vs. CONCAVE).Materials and methodsA total of 47 patients received a single implant in the aesthetic zone and were allocated to one of three groups: (1) CONVEX: customized provisional with a convex emergence profile (n = 15); (2) CONCAVE: customized provisional with a concave profile (n = 16); (3) Control: no provisional restoration (n = 16). Final crowns in groups CONVEX and CONCAVE were fabricated to replicate the emergence profile of the respective provisional restorations. Follow-ups were performed at baseline, 6 months, 1 year and 3 years. The primary outcome was mid-facial mucosal recession and secondary outcomes included clinical, radiographic and aesthetic outcomes as well as profilometric measurements. Multivariable logistic regressions and mixed-effects models were used to compare the groups.ResultsOut of the 47 patients originally included, 42 were available for re-examination at 3 years follow-up. At 3 years, the frequency of mucosal recession amounted to 46.7% in group CONVEX, 13.3% in group CONCAVE and 40.0% in group Control. Adjusted logistic regression models revealed that the CONVEX group was significantly more likely to show recessions at 3 years (odds ratios [ORs]: 7.3, 95% CI: 1.02-52.14, p = 0.048) when compared with the CONCAVE group. No statistically significant difference in recession frequency was observed between the CONVEX and CONCAVE groups between the 1- and 3-year follow-ups (OR: 3.7, 95% CI: 0.30-46.09, p = 0.303).ConclusionThe emergence profile design significantly influences soft tissue stability predominantly within the first year after crown insertion. Whenever clinically feasible, a CONCAVE profile is preferable in the aesthetic zone to maintain the level of the mid-facial mucosal margin and reduce the frequency of recessions.Trial registrationGerman Clinical Trials Register: DRKS00009420.

ObjectivesTo summarize and synthesize evidence-based conclusions on optimal three-dimensional (3D) printing technologies, materials, and clinical protocols for splints, crowns, and dentures.OverviewIn resin vat printing, stereolithography (SLA) offers superior surface finish, while liquid crystal display (LCD) and digital light processing (DLP) excel in speed for larger prints, with LCD providing a cost advantage. Ceramic vat printing yields clinically acceptable strength but is equipment- and time-intensive. Optimal angulation varies by application: splints (0°), crowns (150°-210°), dentures (45°-90°). A 50 μm layer height is preferred for most restorations, with dentures tolerating 100 μm. Commonly used resins employ low-viscosity monomers (e.g., ethoxylated bisphenol A dimethacrylate [Bis-EMA]) that limit stiffness and fast photoinitiators (e.g., ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate [TPO]), requiring 385-405 nm curing.ConclusionsFlexible splints excel in fracture toughness and impact strength; firm splints match milled wear performance. Printed crowns, while weaker than milled options, offer toughness; wear rates remain a concern. Printed denture bases vary in strength but can match or exceed conventional options; printed teeth show favorable wear resistance. Postprocessing, polishing, and bonding protocols critically influence outcomes.Clinical significanceEmploying validated printing parameters, selecting the appropriate resin, and following evidence-based protocols allows clinicians to maximize restoration accuracy and mechanical performance while leveraging 3D printing's efficiency and cost benefits.