Simulating the Entire Clinical Process for an Implant-Supported Fixed Prosthesis: In Vitro Study on the Vertical Implications of Implant-Abutment Connections and Rotational Freedom.

OBJECTIVES: The aim of this in vitro study was to investigate whether and to what extent different scenarios of rotational freedom in different IAC designs affect the vertical dimension of a three-part fixed partial denture (FPD). At the same time, the experimental setup should simulate all clinical and laboratory steps of the implementation of such an FPD as accurately as possible. MATERIAL AND METHODS: Twenty identical pairs of jaw models were fabricated from aluminum, each lower-jaw model holding two implants with conical or flat IACs. Three impressions of each model were taken to fabricate stone casts and three-unit FPDs. Three assembly scenarios were compared for the vertical position stability they offered for these FPDs, differing by how the sequential implant components (impression posts > laboratory analogs > abutments 1 > abutments 2) were aligned with the positional index of the IAC. In this way, a total of 60 stone casts and FPDs were fabricated and statistically analyzed for changes in vertical dimension (p < 0.05). RESULTS: Regardless of whether a conical/flat IAC was used (p > 0.05), significantly greater mean changes in vertical dimension were consistently (all comparisons p < 0.0001) found in a "worst-case scenario" of component alignment alternating between the left- and right-limit stop of the positional index (0.286/0.350 mm) than in a "random scenario" of 10 dentists and 10 technicians with varying levels of experience freely selecting the alignment (0.003/0.014 mm) or in a "best-case scenario" of all components being aligned with the right-limit stop (-0.019/0.005 mm). CONCLUSIONS: The likelihood of integrating a superstructure correctly in terms of vertical dimension appears to vary considerably more with assembly strategies than with IAC designs. Specifically, our findings warrant a recommendation that all implant components should be aligned with the right-limit stop of the positioning index.

Multi-objective optimization of custom implant abutment design for enhanced bone remodeling in single-crown implants using 3D finite element analysis.

The optimal configuration of a customized implant abutment is crucial for bone remodeling and is influenced by various design parameters. This study introduces an optimization process for designing two-piece zirconia dental implant abutments. The aim is to enhance bone remodeling, increase bone density in the peri-implant region, and reduce the risk of late implant failure. A 12-month bone remodeling algorithm subroutine in finite element analysis to optimize three parameters: implant placement depth, abutment taper degree, and gingival height of the titanium base abutment. The response surface analysis shows that implant placement depth and gingival height significantly impact bone density and uniformity. The taper degree has a smaller effect on bone remodeling. The optimization identified optimal values of 1.5 mm for depth, 35° for taper, and 0.5 mm for gingival height. The optimum model significantly increased cortical bone density from 1.2 to 1.937 g/cm3 in 2 months, while the original model reached 1.91 g/cm3 in 11 months. The standard deviation of density showed more uniform bone apposition, with the optimum model showing values 2 to 6 times lower than the original over 12 months. The cancellous bone showed a similar trend. In conclusion, the depth and taper have a significant effect on bone remodeling. This optimized model significantly improves bone density uniformity.

An In Vitro Evaluation of Periotest Implant Stability Measurements Taken on Implant Retained Crowns and Healing Abutments.

OBJECTIVE: To assess the reliability of implant stability measurements recorded with the Periotest device and to investigate the differences in values when these measurements were taken on implant retained crowns and healing abutments. MATERIALS AND METHODS: Fifty-six implants in eight synthetic bone blocks were used to carry out implant stability measurements using the Periotest device by two different operators. Each block constituted an example of bone of density D1, D2, D3, or D4, and two blocks of each density were used. The healing abutments placed were of a height to allow approximately 6 mm of the implant-abutment complex to be supracrestal and temporary crowns were made to match the dimensions of an average central incisor. Descriptive statistics were used to describe the perio test values (PTVs) at each of the different heights on the implant abutments and implant crowns. Means for each site were calculated and distribution of data assessed using the Kruskal Wallis test. The interclass correlation coefficient (ICC) was used to determine the relationship between the PTVs recorded on the implant abutments and implant crowns. RESULTS: The mean PTV (±standard devidation) recorded across all sites was 5.57 ± 11.643 on the implant abutments, and 12.27 ± 11.735 on the temporary crowns. Excellent/good inter-operator ICCs were recorded for the mid-abutment site in all bone blocks D1-D4 (ICC = 0.814, p < 0.001, ICC = 0.922, p < 0.001, ICC = 0.938, p < 0.001, ICC = 776, p < 0.001). For mid crown sites, ICC between operators was excellent/good only for recordings in D2 bone (ICC = 0.897, p < 0.001). CONCLUSIONS: Periotest device seems to be able to reliably measure implant stability across all types of bones when the implant stability is assessed at approximately 3 mm coronal to the implant platform for abutments and 4.5 mm for implant supported single crowns.

Effect of shape and design of the internal connection of tissue-level and bone-level implants on detorque values and removal forces: An in vitro study.

STATEMENT OF PROBLEM: Optimal implant stability and preventing complications such as screw loosening are paramount concerns for implant-supported prostheses. However, studies examining the influence of various internal connection designs on detorque values and removal forces, critical aspects of implant success, are lacking. PURPOSE: The purpose of this in vitro study was to assess the impact of the shape and design of the internal connection in tissue-level and bone-level implants on the detorque value and the force required for abutment removal from the implant. MATERIAL AND METHODS: Forty dental implants were securely mounted in 10×6×20-mm acrylic resin blocks positioned perpendicular to the surface. The implants were divided into 4 groups (n=10): bone-level SM Torx, tissue-level PSI Torx, bone-level UF Hex, and tissue-level UF Hex implants. After exposure to a dynamic loading test at 31.2 N, 2 Hz and 106 cycles, measurements were made of both detorque values and removal forces. Statistical analyses, including 1-way ANOVA with a post hoc Tukey test and Kolmogorov-Smirnov test, were conducted to assess the results (α=.05). RESULTS: The differences in detorque values among the 4 groups were statistically similar (P=.087). In terms of removal force values, tissue-level PSI implants exhibited the highest values, while bone-level UF implants had the lowest values, with significant differences in the removal forces among the 4 groups (P<.001). Pairwise comparisons revealed significant differences among the groups (P<.001), except for the comparison between tissue-level PSI and bone-level SM implants (P=.108). CONCLUSIONS: While detorque values remain consistent across implant types, the shape and design of the internal connection of implants has a significant impact on the removal force required for abutment detachment from the implant.

Strain gauge analysis and fracture resistance of implant-supported PEKK hybrid abutments restored with two crown materials: An in vitro study.

BACKGROUND: Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium and ceramic implant abutments due to its apparent ability to dissipate excessive strain around dental implants. However, the biomechanical behaviors of implant abutment crown systems may change depending on the crown and abutment material combinations used. OBJECTIVES: This study aimed to assess how the crown material affects strain generation and fracture resistance of PEKK hybrid abutment crowns. MATERIAL AND METHODS: Sixteen dummy implants (Ø 3.7 x 11 mm), simulating maxillary first premolars, were restored with 16 milled PEKK hybrid abutments and randomly categorized into two groups according to the crown material (n = 8): Group C, milled composite crowns cemented on PEKK hybrid abutments; and Group Z, ultra-translucent zirconia crowns cemented on PEKK hybrid abutments. Before thermocycling, a cyanoacrylate-base adhesive was used to position two strain gauges on buccal and lingual crestal bone surfaces, and a vertical load (100 N) was applied to the central fossa to record the strain generated. Then, all samples were thermocycled between 5°C and 55°C before being loaded to fracture on a universal testing machine. Modes of failure were observed under an optical microscope, and representative samples were examined using a scanning electron microscope. Independent t-tests were used for intergroup comparisons. The significance level was set at (p < 0.05) for all tests.. RESULTS: The results showed a significant difference between both groups. The zirconia group recorded significantly higher strain and fracture resistance values than the composite group (p < 0.001). There was a positive correlation between the strain developed in peri-implant crestal bone and fracture resistance of the abutment crown complex. CONCLUSIONS: Strains developed in both groups were within the acceptable clinical range. The crown material substantially impacted the strain and fracture of the PEKK hybrid abutment crown system.

Fracture Resistance of CAD/CAM Monolithic Zirconia Crowns Supported by Titanium and Ti-Base Abutments: The Effect of Chewing Simulation and Thermocyclic Aging.

Purpose: To evaluate the effect of chewing simulation and thermocyclic aging on the fracture resistance of CAD/CAM monolithic zirconia crowns supported by titanium and Ti-base abutments. Materials and Methods: Two implant abutment groups-titanium (Ti) and titanium base (Ti-base; Medentika)-were used. A total of 40 mandibular first molar CAD/CAM monolithic zirconia crowns (Vita YZ T) were fabricated, then cemented onto the abutments with Panavia V5. Each abutment group was divided into two subgroups (n = 10). The Ti and Ti-base groups were subjected to a single load until fracture, and the Ti/CT and Ti-base/CT groups (CT: chewing simulation and thermocyclic aging) underwent chewing simulation (1.2 × 106 cycles × 50 N load, 1.4 Hz) and thermocylic aging (3,911 cycles/5°C to 55°C). The fracture resistances of the crowns were tested with a universal testing machine (1 mm/minute). Shapiro-Wilk and one-way ANOVA test were used for statistical analysis (P = .05). Results: The survival rates after chewing simulation and thermocyclic aging were 100% for both CT groups. The fracture resistance values (mean ± SD) of the groups were as follows: Ti = 1,718.18 ± 331.06 N, Ti-base = 1,713.53 ± 233.24 N, Ti/CT = 1,664.82 ± 188.62 N, and Ti-base/CT = 1,551.28 ± 344.79 N. According to one-way ANOVA test results, there was no statistically significant difference between the four groups (P = .526). Conclusion: CAD/CAM monolithic zirconia crowns supported by Ti-base or titanium abutments were found to have sufficient fracture resistance in the treatment of an absent single posterior tooth. However, more in vitro and clinical studies are required to evaluate the long-term performance of Ti-base abutments and CAD/CAM zirconia crowns.

Stability of implant-abutment connection in three different systems after fatigue test.

Aim: Abutment screw loosening of implant-supported prosthesis causes a mismatch between the abutment and the implant. This screw loosening is influenced by the implant-abutment connection type, however, with contradictory results reported in different studies. The present study evaluates the stability of abutment-implant connections in three different systems before and after the fatigue test. Settings and Design: Thirty implants (4.3 mm in diameter and 12 mm in length) were divided into three groups of 10: Implantium, Zimmer, and straight internal hexagonal connection (SIC) implants. Materials and Methods: Two torques of 35 Ncm with an interval of 10 min were applied, followed by measuring removal torque value (RTV). The samples were re-torqued and then underwent a simulation of 1-year chewing clinical performance of dental implant under axial force of 400 N, with a frequency of 8 Hz (one million cycles). After fatigue test, the RTV was calculated and recorded. Statistical Analysis: The mean RTVs obtained before and after cyclic load were analyzed by SPSS version 22 software using multivariate analysis. Results: Significant differences in RTV and role of cyclic loading were found between SIC and Implantium groups (P = 0.006 and 0.021, respectively), as well as between Zimmer and SIC groups (P = 0.032 and 0.006, respectively), but not between Zimmer and Implantium groups (P = 0.771 and 0.248, respectively). Conclusion: The type of connection could affect the screw loosening, the preload loss, and the implant component stability. SIC group revealed the highest RTVs before and after cyclic loading.

SafetyCrown: a patient-centered, fully digital concept for immediate implant restoration following the one-abutment/one-time concept-a pilot case series of a new treatment concept.

INTRODUCTION: The patient-centered SafetyCrown-workflow enables the immediate restoration of posterior missing teeth and short free-end situations following one-abutment/one-time within three visits and only one surgical approach. This prosthodontic rehabilitation aims to combine the advantages of cemented and screw-retained restorations. REPORT: The concept has been performed with 4 restorations in 3 patients and followed up for up to 1 year (mean: 11.2 months) without technical and/or biological complication. Visit 1: Intraoral optical impression, CBCT, and tooth shade selection. Virtual implant planning is performed, and a surgical guide is printed. After exporting the planned implant position, a tooth-colored abutment is fabricated from zirconia with a 1-mm supragingival cementation line, adhesively bonded to a titanium base. Visit 2: Fully navigated implant placement with insertion of the definitive abutment. Subsequently, optical impressions are prepared for A: immediate restoration using a PMMA crown without functional contacts; B: definitive crown fabricated from monolithic zirconia and individualized. The localization of the screw channel is marked using stain thus permitting precise screw channel access, if necessary. Visit 3: After osseointegration of the implant, the definitive crown is adhesively cemented supragingival. In a retrospective analysis of PROMs ('How stressful was the treatment process […]?' (0 = not stressful at all, 100 = very stressful), mean VAS score for SafetyCrown of 14 (SD 11.7) and 29.8 (SD 23.1) for standard procedure were present. CONCLUSION: The SafetyCrown offers a shortened, patient-oriented concept for implant-supported single-tooth reconstructions omitting second-stage surgery. Clinical performance and hypothesized prosthodontic benefits require confirmation via an RCT.

[Computed X-ray microtomography of the junction of dental implants with standard and custom abutments]. / Komp'yuternaya rentgenmikrotomografiya uzla soedineniya dental'nykh implantatov so standartnymi i individual'nymi abatmentami.

THE AIM OF THE STUDY: Comparative study of the precision of the junction of modern implant systems with standard and custom abutments. MATERIALS AND METHODS: The study was carried out by the method of computed X-ray microtomography on an X-ray microtomograph Heliscan micro CT using the ImageJ program in the laboratory «Systems for Microscopy and Analysis¼ of the Skolkovo Technopark. The measurement of the gap width between the implant and the abutment for each sample was carried out at 20 points according to the algorithm: the total length of the connection between the implant and the abutment; step (distance) between 5 equidistant points along the contact between the abutment and the implant; the measurements were repeated in 2 perpendicular sections along the joint node axis. The study was conducted on the example of seven implant systems common in Russia. The effect on the implant-abutment assembly of a multiple functional load of 250 N at an angle of 45° (7.6 million cycles) was studied. RESULTS: It has been established that the precision of the junction of modern implants with standard abutments is different and is characterized by the length of the contact from 268 to 1300 µm, the gap at the level of the platform from 5.0 to 11.7 µm, and the asymmetry of the contact in diameter by 2.4-14.2 µm. Abutments individually made in modern CAD/CAM laboratories do not have significant dimensional differences with standard abutments, but they have technological defects. The functional load expands and deforms the gap between the implant and abutment junction in the upper half of their contact. CONCLUSION: The results obtained demonstrate the capabilities of the computer X-ray microtomography method, which can be used to control the quality of manufacturing collapsible dental implants, the accuracy of manufacturing individual abutments in CAD/CAM laboratories, as well as in the development of new dental implant systems. The dimensional parameters of the junction node determine the advantages of the deep cone connection of the implant and the abutment.

Additively manufactured implant abutment screw-access guide to remove a cement-retained implant crown: A technique.

A complete digital workflow to remove a cement-retained implant-supported crown by using an additively manufactured implant abutment screw-access guide is described. The existing cone beam computed tomography (CBCT) scan was superimposed on the digital scans of the patient, which facilitated the visualization of the implant abutment screw access and guided the design of the device. Advantages of the technique described include the precise translation of the implant abutment screw access, safe removal of the implant crown, and conservative clinical intervention.

The ability to screw-retain single implant-supported restorations in the anterior maxilla: A CBCT analysis.

STATEMENT OF PROBLEM: Evidence to validate the routine use of angled screw-channel abutments in the anterior maxilla is sparse. If properly planned, they might provide surgical and prosthetic benefits. PURPOSE: The purpose of this observational study was to determine the prevalence of digitally placed implants in the anterior maxilla that would allow screw-retained implant-supported restorations with either a straight or an angled screw-channel abutment. MATERIAL AND METHODS: Two hundred cone beam computed tomography (CBCT) scans met the inclusion criteria for retrospective analysis and digital implant planning. Virtual implants were planned for randomly selected anterior maxillary teeth by using the anatomic crown and root position. Virtual abutments of varying angulation were attached to the implants to determine the ability to screw retain a restoration with either a straight or an angled screw-channel abutment. RESULTS: One hundred fifty-two (76%) sites required an angled screw-channel abutment to enable screw retention. Forty-eight (24%) sites allowed screw retention with a straight abutment. The percentage of implants requiring angled or straight abutments varied significantly among anterior teeth (P<.005). One hundred nine (71.7%) angled screw-channel abutment sites required a 5-degree abutment, 41 (26.9%) required a 10-degree abutment, and 2 (1.3%) required a 15-degree abutment. Among the anterior teeth, lateral incisors presented a greater need for angled screw-channel abutments. None of the implants in the present study needed cement-retained restorations. CONCLUSIONS: Angled abutments allowed for screw-retained restorations on digitally planned implants in the anterior maxilla. The required angular correction to a screw-retained restoration was ≤15 degrees. Screw-retained restorations were frequently achievable (76%) with the use of angled screw-channel abutments or with straight abutments (24%), and lateral incisors presented a greater need for angled screw-channel abutments.

Biocompatibility of Lithium Disilicate and Zirconium Oxide Ceramics with Different Surface Topographies for Dental Implant Abutments.

Gingivafibroblasts were cultured on lithium disilicate, on zirconia dioxide, and on titanium with two different surface roughnesses (0.2 µm and 0.07 µm); Proliferation (MTT), Living/Dead staining, cytotoxicity (LDH), proliferation (FGF2), and inflammation (TNFα) were analyzed after 1 day and 21 days. Furthermore, alteration in cell morphology (SEM) was analyzed. The statistical analysis was performed by a Kruskal-Wallis test. The level of significance was set at p < 0.05. There were no distinct differences in cellular behavior between the tested roughness. There were slight differences between tested materials. Cells grown on zirconia dioxide showed higher cytotoxic effects. Cells grown on lithium disilicate showed less expression of TNFα compared to those grown on zirconia dioxide or titanium. These effects persisted only during the first time span. The results indicate that the two tested high-strength ceramics and surface properties are biologically suitable for transmucosal implant components. The findings may help clinicians to choose the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.

Failure Modes and Survival of Anterior Crowns Supported by Narrow Implant Systems.

The reduced hardware design of narrow implants increases the risk of fracture not only of the implant itself but also of the prosthetic constituents. Hence, the current study is aimed at estimating the probability of survival of anterior crowns supported by different narrow implant systems. Three different narrow implant systems of internal conical connections were evaluated (Ø3.5 × 10 mm): (i) Active (Nobel Biocare), (ii) Epikut (S.I.N. Implant System), and (iii) BLX (Straumann). Abutments were torqued to the implants, and standardized maxillary incisor crowns were cemented. The assemblies were subjected to step-stress accelerated life testing (SSALT) in water through load application of 30 degrees off-axis lingually at the incisal edge of the crowns using a flat tungsten carbide indenter until fracture or suspension. The use level probability Weibull curves and reliability for completion of a mission of 100,000 cycles at 80 N and 120 N were calculated and plotted. Weibull modulus and characteristic strength were also calculated and plotted. Fractured samples were analyzed in a stereomicroscope. The beta (ß) values were 1.6 (0.9-3.1) and 1.4 (0.9-2.2) for BLX and Active implants, respectively, and 0.5 (0.3-0.8) for the Epikut implant, indicating that failures were mainly associated with fatigue damage accumulation in the formers, but more likely associated with material strength in the latter. All narrow implant systems showed high probability of survival (≥95%, CI: 85-100%) at 80 and 120 N, without significant difference between them. Weibull modulus ranged from 6 to 14. The characteristic strength of Active, Epikut, and BLX was 271 (260-282) N, 216 (205-228) N, and 275 (264-285) N, respectively. The failure mode predominantly involved abutment and/or abutment screw fracture, whereas no narrow implant was fractured. Therefore, all narrow implant systems exhibited a high probability of survival for anterior physiologic masticatory forces, and failures were restricted to abutment and abutment screw.

La utilización de pilares transmucosos definitivos de colocación inmediata / The use of immediate placement of definitive transmucosal abutments

El uso de pilares de cicatrización transmucosos previos a la colocación del pilar protésico definitivo es una técnica que se ha desarrollado durante muchos años en la implantología clásica. La desconexión y conexión de forma repetida de estos pilares o aditamentos dan lugar a una respuesta ósea negativa que se manifiesta en forma de pérdida de hueso a nivel de la cresta marginal, acompañada por una migración apical de tejidos blandos. Este artículo pretende realizar una revisión de la literatura del estado actual del uso de los pilares transmucosos definitivos con colocación inmediata el día de la inserción de los implantes y el mantenimiento del sellado biológico, minimizando la pérdida ósea periimplantaria y remodelando de forma adecuada los tejidos blandos adyacentes, frente al protocolo tradiciónal del uso de aditamentos que se desconectan en multiples ocasiones produciendo pérdida ósea periimplantaria. La evidencia científica sugiere que los mejores resultados biológicos, estéticos y funciónales se consiguen con el uso del pilar definitivo colocado de forma inmediata a la inserción del implante, especialmente en implantes colocados de forma yuxtacrestal y en implantes postextracción

The use of transmucosal healing abutments before the placement of the definitive prosthetic abutment is a technique that has been developed for many years in classical implantology. Repeated disconnection and connection of theses abutments result in a negative bone response that manifests as bone loss at the marginal ridge level, accompanied by apical soft tissue migration. This article aims to review the current status in the scientific literature of the use of the definitive transepithelial abutments with immediate placement on the day of implant insertion and maintenance of the biological seal, minimizing peri-implant bone loss and adequately remodeling the adjacent soft tissues, compared to the traditional protocol of the use of abutments that are disconnected on multiple occasions producing peri-implant bone loss. Scientific evidence suggests that the best biological, aesthetic, and functional results are achieved with the use of the definitive abutment placed immediately after implant insertion, especially in yuxtacrestal implants and post-extraction implants

La respuesta tisular a implantes dentales con plataforma reducida (platform switching) / Tissue response to dental implants with platform switching

La evolución en los diseños de los sistemas de implantes y en la configuración de los pilares protésicos ha desarrollado el concepto de plataforma reducida que comprende la colocación de un pilar más estrecho que la plataforma del implante para aumentar su distancia de la interfase hueso-implante. La plataforma reducida es considerada un factor importante para preservar la estabilidad del hueso crestal y de los tejidos blandos y asegurar el éxito de los implantes dentales a largo plazo. La plataforma reducida reduce las fuerzas oclusales y la contaminación bacteriana en la interfase entre el hueso crestal y el implante. Los estudios experimentales en animales y clínicos en pacientes muestran su eficacia para prevenir la pérdida ósea y de los tejidos blandos periimplantarios

The evolution of designs of implant systems and abutments configurations has developed the concept of platform-switching that involves the connection of a narrower abutment to the platform implant to allow horizontal distance of the interface bone-implant. Platform-switching is considered an important factor to preserve the stability of crestal bone and soft tissue ensuring the success of dental implants in the long-term follow-up. Platform-switching reduces the forces of occlusal loading and bacterial contamination in the interface between the crestal bone and the implant. Experimental studies in animals and clinical studies in patients showed that implants with platform-switching have demonstrated the effectiveness to prevent peri-implant bone loss and subsequent soft tissue los

Measurement of gap between abutment and fixture in dental conical connection implants. A focused ion beam SEM observation

BACKGROUND: The aim of the authors was to examine the abutment-fixture interface in Morse-type conical implants in order to verify gaps at this level using a new microscopical approach. MATERIAL AND METHODS: In this in vitro study, 20 abutment-fixture complexes were prepared by sectioning (longitudinal and cross-sectional to the long axis) with a microtome and then with a focused ion beam (FIB). This is a micrometric machine tool that uses gallium ions to abrade circumscribed areas to dig deeper into the cuts obtained with the microtome in order to eliminate cut-induced artifacts. This is because the FIB abrasion is practically free from artifacts, which are normally generated by the action of the microtome blades or other techniques. Samples were then observed by scanning electron microscopy (SEM). RESULTS: The observation of the abraded parts with the FIB permitted measurement of the real gap between the implant-abutment components. A variable amount of gap was retrieved (from 0 to 3 μm) by the observations, confirming the non-hermetic nature of the connection. It has to be pointed out that in approximately 65% of cases, the gap accounted for less than 1 μm. CONCLUSIONS: The reported data confirmed that the analyzed connection system allowed for minimal gap. However, from the evidence of the present analysis, it cannot be assumed that the 2 parts of a Morse-type conical implant are fused in 1 piece, which would create a perfectly matched hermetic connection

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Artificial intelligence in fixed implant prosthodontics: a retrospective study of 106 implant-supported monolithic zirconia crowns inserted in the posterior jaws of 90 patients.

BACKGROUND: Artificial intelligence (AI) is a branch of computer science concerned with building smart software or machines capable of performing tasks that typically require human intelligence. We present a protocol for the use of AI to fabricate implant-supported monolithic zirconia crowns (MZCs) cemented on customized hybrid abutments. METHODS: The study protocol consisted of: (1) intraoral scan of the implant position; (2) design of the individual abutment and temporary crown using computer-aided design (CAD) software; (3) milling of the zirconia abutment and the temporary polymethyl-methacrylate (PMMA) crown, with extraoral cementation of the zirconia abutment on the relative titanium bonding base, to generate an individual hybrid abutment; (4) clinical application of the hybrid abutment and the temporary PMMA crown; (5) intraoral scan of the hybrid abutment; (6) CAD of the final crown with automated margin line design using AI; (7) milling, sintering and characterisation of the final MZC; and (8) clinical application of the MZC. The outcome variables were mathematical (quality of the fabrication of the individual zirconia abutment) and clinical, such as (1) quality of the marginal adaptation, (2) of interproximal contact points and (3) of occlusal contacts, (4) chromatic integration, (5) survival and (6) success of MZCs. A careful statistical analysis was performed. RESULTS: 90 patients (35 males, 55 females; mean age 53.3 ± 13.7 years) restored with 106 implant-supported MZCs were included in the study. The follow-up varied from 6 months to 3 years. The quality of the fabrication of individual hybrid abutments revealed a mean deviation of 44 µm (± 6.3) between the original CAD design of the zirconia abutment, and the mesh of the zirconia abutment captured intraorally at the end of the provisionalization. At the delivery of the MZCs, the marginal adaptation, quality of interproximal and occlusal contacts, and aesthetic integration were excellent. The three-year cumulative survival and success of the MZCs were 99.0% and 91.3%, respectively. CONCLUSIONS: AI seems to represent a reliable tool for the restoration of single implants with MZCs cemented on customised hybrid abutments via a full digital workflow. Further studies are needed to confirm these positive results.

Morse taper performance: A finite element analysis study.

OBJECTIVES: To evaluate and compare the magnitude and distribution of stresses generated on implants, abutments and first molar metal-ceramic crowns using finite element analysis. METHODS: Preliminary three-dimensional models were created using the computer-aided design software SolidWorks. Stress and strain values were observed for two distinct virtual models: model 1 - Morse taper and solid abutment; model 2 - Morse taper and abutment with screw. A load (250 N) was applied to a single point of the occlusal surface at 15° to the implant long axis. Von Mises stresses were recorded for both groups at four main points: 1) abutment-retaining screws; 2) abutment neck; 3) cervical bone area; 4) implant neck. RESULTS AND CONCLUSION: Model 1 showed a higher stress value (1477.5 MPa) at the abutment-retaining screw area than the stresses found in model 2 (1091.1 MPa for the same area). The cervical bone strain values did not exceed 105 µm for either model.

Is clinical experience important for obtaining the primary stability of dental implants with aggressive threads? An ex vivo study

Background: The aim of this study was to investigate the clinicians' experience on maintaining the primary stability of implants with aggressive threads belonging to a novel dental implant system. Material and Methods: Three hundred implants with aggressive threads were inserted in fresh bovine ribs mimicking Type IV bone by five clinicians which were classified according to their previous experience of total number of implant insertion. An independent examiner measured the primary stability of all implants after insertion by using resonance frequency analysis (RFA), electronic percussive testing (EPT) and removal torque methods. Results: No significant differences were detected between the stability values measured by the clinicians (p> 0.05) except the Periotest values (PTVs) of the non-experienced clinician. PTVs of the non-experienced clinician were significantly higher than the PTVs of the expert and good clinicians (p<0.05). Significantly higher stability values were detected in the secondary insertion of the non-experienced clinician as compared to her initial insertion values (p<0.05). No significant differences were detected between the first and second measurements of the other clinicians (p> 0.05). Conclusions: Within the limitations of this ex-vivo study, it may be concluded that experience does not play an important role in maintaining the stability of implants with aggressive threads

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Analysis of marginal bone loss and implant stability quotient by resonance frequency analysis in different osteointegrated implant systems. Randomized prospective clinical trial

Background: The aim of the present prospective clinical study is to compare the stability of the implant-bone interface by the ISQ quotient and marginal bone loss (MBL) rate during one year of follow-up in four system implants with the same surface and different design. Material and Methods: Prospective randomized clinical trial of 21 patients in which four implant systems with the same surface and different design were placed. Patients were treated by the same operator following a similar surgical protocol with submerged technique. The second surgery to perform the prosthesis was performed at 3 months. All patients went to their review at 6 months and a year. A periapical radiograph for crestal bone analysis and an Implant stability quotient by resonance frequency analysis (ISQ) analysis were taken at baseline and the reviews. Results: No statistically significant differences were found in the Implant stability quotient by resonance frequency analysis and Marginal Bone Loss in the four types of implants. The ISQ increased from the moment of insertion of the implant until the revision to the year, showing an increase of the stability implant, being this increasing less between the 6 months and the year. Conclusions: Differences in the design of the four implants tested in this study did not show statistically significant differences in any of the variables studied, so the implant design does not influence implant stability and marginal bone loss in the first year after placement

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