Abutment Connection Research Articles

Molding Quality and Biological Evaluation of a Two-Stage Titanium Alloy Dental Implant Based on Combined 3D Printing and Subtracting Manufacturing.

Metal 3D printing has been used in the manufacturing of dental implants. Its technical advantages include high material utilization and the capacity to form arbitrarily complex structures. However, 3D printing alone is insufficient for manufacturing two-stage titanium implants due to the limited precision in printing titanium alloy parts. In this study, 3D printing was employed to create the implant structure, subsequently complemented by mechanical processing to refine the implant abutment connection and neck. Additionally, the mechanical properties of 3D-printed titanium alloy implants were evaluated through tensile and dynamic fatigue testing. The MTT assay was employed to assess the cytotoxicity of 3D-printed titanium alloy dental implants. The impact of bone union and osteogenesis from 3D-printed titanium alloy dental implants was investigated through in vivo experimentation. The results demonstrated that combining 3D printing with subsequent machining constitutes a viable method for the manufacture of two-stage titanium dental implants. Test results for mechanical properties indicated that heat-treated 3D-printed titanium alloy dental implants possess significant tensile strength and fatigue resistance and are capable of withstanding the robust chewing forces in the oral cavity. In vitro findings revealed that sandblasted and acid-etched 3D-printed titanium alloy exhibited negligible cytotoxicity, with osteoblast differentiation of hMSCs being more pronounced compared with the control group. In vivo studies indicated that no significant differences were observed in bone volume fraction, bone-implant contact rate, and unscrewing torque between 3D-printed titanium alloy dental implants and commercial SLA surface implants at both 1 and 3 months postimplantation.

Retrievability of Fractured Abutment Screws and Damage to Implant–Abutment Connections: An In Vitro Comparative Analysis of Conventional vs. Drilling Techniques

This study aimed to evaluate the retrievability and potential damage to implant–abutment connections caused by fractured abutment screw removal using conventional and drilling techniques. A total of forty abutment screws were randomly inserted into forty dental implants, and then they were fractured and extracted using different removal methods: Group A employed a conventional approach utilizing an exploration probe and an ultrasonic device without irrigation (n = 10) (conventional); Group B used the Phibo drilling removal system without irrigation (n = 10) (Phibo); Group C utilized the Rhein83® drilling removal system without irrigation (n = 10) (Rhein83); and Group D implemented the Sanhigia® drilling removal system without irrigation (n = 10) (Sanhigia). Pre- and postoperative micro-computed tomography (micro-CT) scans were performed on the dental implants, and Standard Tessellation Language (STL) digital files were generated for morphometric analysis to measure the wear volume. ANOVA was used to assess the volumetric differences (mm3) and percentage ratios of the internal thread volumes of the implant–abutment connections before and after the procedures. Results: This study found no statistically significant differences in the volumetric and percentage ratios of internal threads among the implant groups (Phibo, Rhein83, Sanhigia, and conventional). However, the success rate for retrieving fractured abutment screws was higher (90%) with the drilling systems compared to the conventional technique (50%). These results suggest that drilling systems are more effective for the retrieval of damaged screws. Although drilling techniques without irrigation demonstrated higher removal efficiency compared to the conventional method, both approaches resulted in similar wear volumes at the implant–abutment connections when used to extract fractured screws.

A Biomechanical Comparative Analysis of Abutment Screw Head Designs on Preload Stability Under Oblique Compressive Forces: An In Vitro Pilot Study.

The purpose of this study was to examine the impact of abutment screw head sizes on preload stability when secured to a standard external hex implant under oblique compressive forces. Fifteen metal crowns were divided into 3 equal groups. The first group had 5 angulated cemented crowns connected to a 3-mm-tall straight hexagonal abutment with an external hex abutment screw. The second and third groups each had 5 straight cemented crowns attached to a tapered abutment with flat-slotted and internal hex abutment screws, respectively. Samples were subjected to a static cyclic load until failure. Kruskal-Wallis H, Dunn, and one-way analysis of variance with Tukey honestly significant difference tests were performed. Cemented straight crowns supported by an angled abutment connected to implants with flat-slotted and internal hex abutment screw heads failed at an average of 4.24 × 106 cycles ± 3.31 SD and 12.67 × 106 cycles ± 5.47 SD, respectively. Cemented angled crowns supported by a straight abutment connected to identical implants with an external hex abutment screw survived 18.02 × 106 cycles ± 4.49 SD. The periotest value rate of change increased at a higher rate in crowns supported by angled abutments compared with straight abutments (p < .05). No cement failure was observed. Under the experimental conditions, larger abutment screw head sizes demonstrated greater stability of the abutment-abutment screw joint interface. Based on the in vitro findings, no cement failure was observed between the cemented crown and abutment connection. Future research with standardized comparative setups and larger sample sizes is needed.

A Biomechanical Evaluation of Distal Tilting Implants in All-on-Four Rehabilitation with Mild Mandibular Resorption: A Finite Element Analysis Study.

The geometry of implants plays a crucial role in the success of All-on-Four treatments for the lower jaw. This study builds upon prior research by evaluating the biomechanical performance of implant-supported prostheses in full-arch fixed dental restorations, specifically focusing on different implant lengths and connection types in cases of mild atrophic resorption of the mandible. Four groups were analyzed using finite element analysis (FEA): We utilized 13 or 18 mm posterior 17-degree tilting implants, each paired with two kinds of abutment connections. The external hexagon connection (EHC) group utilized 4 mm diameter implants, while the internal hexagon connection (IHC) group employed 4.3 mm diameter implants. A vertical force was applied to the cantilever region located at the distal side of the posterior implant. The maximum stress regions were observed in prosthetic screws and multi-unit abutments (MUAs) across all groups, with the lowest von Mises stress values noted in the bone. Stress peaks for implant screws and fixtures in the 13 mm group were 19.98% and 11.42% lower, respectively, compared to the IHC group. Similarly, in the 18 mm group, stress peaks were reduced by 33.16% and 39.70% for the EHC group compared to the IHC group. The stress levels on all components remained below the ultimate strength of the titanium alloy. For the same implant lengths, the stress in the prosthetic screw, MUAs, implant screw, and implant fixture positions was lower in the EHC group. When implant length was increased, a decrease in stress levels was observed in the implant screw and fixture of the EHC group and only in the implant screw of the IHC group. However, an increase in stress was noted in the prosthetic screw and MUAs for both groups.

Peri-implant clinical profile and subgingival yeasts carriage among cigarette-smokers with peri-implant mucositis

BackgroundThe present observational clinical investigation is based on the hypothesis that subgingival yeast carriage (SYC) is higher in cigarette-smokers with peri-implant mucositis (PM) than non-smokers with and without PM.ObjectiveThe aim was to assess peri-implant clinical profile and SYC among cigarette-smokers with PM.MethodologyParticipants were divided into four groups: Group-1—Cigarette-smokers with PM; Group-2—Cigarette-smokers without PM; Group-3—Non-smokers with PM; and Group-4—Non-smokers without PM. Information on duration and daily frequency of cigarette smoking (pack years), age, gender, familial history of smoking and most recent visit to a dentist and/or dental hygienist was collected. The following information was retrieved from healthcare records: implant dimensions, implant insertion torque, depth of insertion (credidastal or subcrestal), implant abutment connection, jaw location, implant surface characteristic, and mode of implant prosthesis retention. Peri-implant modified plaque and gingival indices (mPI and mGI), probing depth (PD) and crestal bone loss were recorded. Subgingival biofilm samples were collected, and SYC was recorded in colony forming units per milliliter (CFU/ml). P < 0.05 were considered statistically significant.ResultsEighty male individuals (20, 19, 21 and 20 individuals were included in groups 1, 2, 3 and 4, respectively) were included. The mPI was higher in Group-1 than groups 2 (P < 0.05) and 4 (P < 0.05). The mPI was higher in Group-3 than groups 2 (P < 0.05) and 4 (P < 0.05). The mGI was higher in Group-3 than groups 1 (P < 0.05), 2 (P < 0.05) and 4 (P < 0.05). The PD was higher in Group-1 than groups 2 (P < 0.05) and 4 (P < 0.05). The PD was higher in Group-3 than Groups 2 (P < 0.05) and 4 (P < 0.05). The CFU/ml were higher in Group-1 than groups 2 (P < 0.05) and 4 (P < 0.05). The CFU/ml were higher in Group-3 than groups 2 (P < 0.05) and 4 (P < 0.05).ConclusionPeri-implant soft-tissue inflammatory parameters are worse and SYC is higher in moderate smokers than light smokers with PM and non-smokers without PM.

Mandibular Ridge Augmentation With Interpositional Osteoplasty To Improve Crown Implant Ratio

Oral rehabilitation with implants is a predictable treatment modality. Long term survival of the implants is influenced by multitude of factors including biological, technical, physiological and biomechanical factors. Among the biomechanical factors, crown implant ratio plays a critical role. Improper crown implant ratio causes bending effect on the implants due to the horizontal forces during mastication. These forces act on the implant abutment connection area and at the marginal bone compromising the treatment prognosis. To negate this consequence surgically, a ridge augmentation procedure can be a viable option. This case report is one such scenario wherein inter-positional osteoplasty is used to augment the mandibular anterior ridge with autogenous bone graft from iliac crest along with the simultaneous placement of implants followed by the replacement of missing teeth with a fixed hybrid prosthesis. Key words: Crown implant ratio, hybrid prosthesis, sandwich osteoplasty

Ten-Year Follow-Up of Oral Implants in Bone With Limited Bucco-Oral Dimensions: A Prospective Case Series.

It has been suggested that 1-2 mm of bone width at the buccal and lingual aspect is required for a successful long-term implant outcome. Low levels of evidence support this minimum threshold of bone width. This prospective study aimed at evaluating the outcome of implants placed in alveolar ridges with limited bucco-oral dimensions. One-hundred implants (dia. 3.5 mm) were placed in 28 patients with narrow alveolar ridge dimensions (<4.5 mm width) without augmentation procedures and conventionally loaded. Intra-oral radiographs were taken at implant placement and abutment connection and at 1, 2, 3, 5 and 10 years of follow-up. At the 10-year follow-up (21 patients; 75 implants), full-mouth periodontal charting was performed, and the peri-implant keratinized tissue width and attachment type were recorded. Two calibrated periodontists analysed the peri-implant bone changes. After 10 years, all implants showed successful osseointegration and a cumulative survival rate of 100%. The implants were placed 0.85 mm ± 0.89 mm subcrestally. After 10 years, the marginal bone was located 1.59 ± 2.11 mm apical to the implant shoulder. Throughout this period of follow-up, the mean annual marginal bone loss was 0.094 mm. Furthermore, 84% of implants in 72% of patients presented with bleeding on probing. After 10 years of functional loading, implants placed in alveolar ridges with limited bucco-oral dimensions (≤4.5 mm) exhibited only minimum marginal bone loss.

Comparative study of axial displacement in digital and conventional implant prosthetic components

Axial displacement of prosthetic components is a major concern in implant dentistry, particularly during screw tightening. However, implant manufacturers provide different recommended torques for tightening implant prosthetic components, which can lead to errors in prosthesis fit before and after impression making. Implant–abutment connection angle or abutment geometries can affect axial displacement. This study aimed to compare the axial displacement between conventional and digital components based on the tightening torque and differences in the implant–abutment connection angles and geometries. The results showed that scan bodies with different implant-abutment connection geometries exhibited smaller axial displacement with increasing tightening torque than other prosthetic components. Except for the scan bodies, there was no difference in the axial displacement of prosthetic components when tightened with the same torque. However, regardless of the use of digital or conventional method of impression making, the axial displacement between the impression making component and the abutment when tightened to the recommended torques were significantly different. In addition, axial displacement was affected by the internal connection angle. The results of this study indicate that the tightening torque and geometry of prosthetic components should be considered to prevent possible misfits which can occur before and after impression making.

Examination of Various Abutment Designs Behavior Depending on Load Using Finite Element Analysis.

Studies on dental implant abutments' geometric design and material selection offer significant innovations and results. These studies aim to improve the abutments' functionality and aesthetic performance, minimize microcavities' formation, and ensure implant-supported prostheses' longevity. For example, CAD-CAM fabricated custom abutments have been found to produce a better marginal fit and fewer microgaps than standard abutments. In an in vitro study, transepithelial abutments offered lower microgap values than titanium-based abutments and provided a better fit at the implant-abutment interface. It is known that studies to improve mechanical and biological performance with Polyether Ether Ketone (PEEK) material have been addressed. New materials such as PEEK and zirconia have offered significant advantages in biocompatibility and aesthetics. Along with those studies, different abutment designs are also important. Abutment geometry is optimized to improve stress distribution and minimize peri-implant bone loss. In implant and abutment connections with different angles, mechanical life performances may vary depending on static and dynamic load. These studies emphasize the importance of material research on different types of connections to improve dental implants' durability, homogeneous load distribution, and reliability. The abutment parts used in implant treatment are insufficient to distribute the load homogeneously against chewing pressure due to their materials and geometry. Non-uniform load distribution damages the abutment and the prosthetic crown, accelerating the wear process. This study aimed to create different abutment designs to improve dental implants' biomechanical performance and longevity. This study aimed to increase the mechanical durability of the implant-abutment connection by reducing stress concentrations in response to masticatory compression on the abutment in different directions and forces and to guarantee the long-term success of the implant system by providing a more homogeneous stress distribution. It aimed to apply different forces in the axial direction to these models in a simulation environment and to calculate and compare the deformation and stress load distribution. As a method, three-dimensional models of the parts used in implant treatments and forming the implant system were designed. Different abutment designs were created with these models. Taking the current material values used in implant treatments as a reference, finite element analysis (FEA) was performed by applying different axial loads to each implant system model in the ANSYS software (version 24.1). Comparative analysis graphs were prepared and interpreted for the stress values obtained after the applied load. This study evaluated the mechanical performance of different abutment models (A, B, C, D, and E) under a 100 N load using the Kruskal-Wallis test. The Kruskal-Wallis test showed significant differences between the groups (p < 0.001). The greatest difference was observed between models E and A (q' = 6.215), with a significant difference also found between models C and A (q' = 3.219, p < 0.005). Regarding stress values, the highest stress on the abutment was observed in Model B (97.4 MPa), while the lowest stress was observed in Model E (9.6 MPa). The crown exhibited the highest stress in Model B (22.7 MPa) and the lowest in Model E (17.3 MPa). The implant stress was highest in Model C (14.8 MPa) and lowest in Model B (11.3 MPa). The stress values for the cortical bone and cancellous bone were quite similar across the models, showing no significant differences. These findings indicate that the abutment design and material selection significantly impact mechanical performance. Among the implant systems created with five different abutment models, in which the existing abutment geometry was also compared, homogeneous and axial distribution of the load on the abutment was achieved, especially with viscoelastic and surface area increased abutment designs. Clinically, the inadequacy and limited mounting surface or geometry of the abutments used in today's implant treatment applications have led to different design searches. It was concluded that the designs in this study, which are considered alternatives to existing abutment models, contribute positively to the mechanical life of the abutment material, considering the von Mises stresses and directions. This study brings a new perspective to today's practices and offers an alternative to treatment practices.

An Evaluation of microbial leakage in three different implant abutment connections using a quantitative analysis of presence of staphylococci bacteria an in vitro study

An Evaluation of microbial leakage in three different implant abutment connections using a quantitative analysis of presence of staphylococci bacteria an in vitro study

Evaluation of Marginal Bone Loss and Implant Survival in Internal Tapered Versus Internal Non-Tapered Connection: A Systematic Review and Meta-Analysis

Introduction- The dental implant is a dependable treatment option for partially &amp; completely edentulous patients. The success of the implant placement and survival also depends upon the type of implant and the type of implant- abutment connection. There are two different implant- abutment connections, external connection and internal connection. The external connection has several disadvantages, so clinicians nowadays prefer internal connection for long-term success. Internal connections have two types of connection internal hex and internal tapered connection, and this systematic review and meta- analysis aimed to compare these two different connections.  Material and Methods- This review and meta-analysis used the population, intervention, control, and outcome (PICO) criteria to develop and answer a specific research question, "Is there a disparity in bone loss and implant survival between patients who had an internal tapered implant-abutment connection and those who had an internal non-tapered implant-abutment connection?" for a developed question there are some criteria's which include and exclude some studies from the meta-analysis.  Result- A final tally of 343 participants with 436 implants was assessed. In the mean 20.5-month follow-up time, the percentages of outcomes were comparable. The three assessed studies reported that the tapered connection's survival rate was higher. For the primary outcome, five out of the six included studies assessed the marginal bone loss surrounding the implants. Marginal bone loss of the internal tapered connection was lower than that of the internal non-tapered connection.  Conclusion- Internal connections with tapered connections had somewhat less marginal bone loss than internal non- tapered connections and more survival rate of implants.

Early implant placement versus ridge preservation and delayed implant placement: Analysis of profilometric, clinician- and patient-reported outcomes from a two-centre RCT.

To compare early implant placement (EP) to alveolar ridge preservation and delayed implant placement (ARP/DP) in terms of contour changes, along with clinician- and patient-reported outcome measures (PROMs) until the delivery of the implant-supported restoration. Patients with a failing single tooth in the maxilla or mandible were recruited in two centres. After tooth extraction, patients were randomly assigned (1:1) to either EP or ARP/DP. At abutment connection and crown delivery, the buccal contour changes at 3 mm below the mucosal margin (primary outcome) along with clinician- (ease of treatment) and patient-reported outcomes were assessed using numeric rating scales and OHIP-14. A total of 46 patients were analysed. The mean buccal contour at abutment connection decreased by -1.2 ± 0.6 mm in group EP and -1.6 ± 0.8 mm in group ARP/DP (estimated mean difference; 0.45 [95%CI, -0.02; 0.94]; p = .061) with no significant differences between the groups. ARP/DP was consistently easier than EP across all stages of the surgery (estimated mean difference; 2.0 [95%CI, 1.3; 2.7] p < .001): during flap elevation (EP: 4.8 vs. ARP/DP: 1.6), implant placement (EP: 5.7 vs. ARP/DP: 2.2) and wound closure (EP: 3.4 vs. ARP/DP: 1.6). Both interventions improved quality of life but patients who underwent ARP/DP were significantly more satisfied at the time of crown delivery (ARP/DP: 9.6 vs. EP: 9.1, p = .02). EP and ARP/DP show no significant differences in buccal contour changes, aesthetics and patient-reported outcomes. However, ARP/DP is an easier procedure at all stages of the surgery compared to EP and could therefore be the preferred therapy for less experienced clinicians.

A Multivariate Logistic Regression Analysis of Risk Factors for Peri-implant Bone Loss.

To evaluate multiple risk factors of peri-implant bone loss. A case-control study was conducted on patients who had received dental implants treatment from January 2018 to December 2021. Implants with bone loss were included in the case group, and implants with no bone loss were included in the control group. Risk factors including history of periodontitis, abutment connection type, implant surface, diameter, location, three-dimensional position, opposing dentition, adjacent teeth, prosthetic type, retention type and custom abutment were evaluated. A multivariate logistic regression model was used to evaluate these risk factors, providing corresponding odds ratios (ORs) with 95% confidence intervals (CIs). A total of 776 implants in 479 patients were included in the analysis. The number of implants in the case group and the control group were 84 and 692, respectively. Cement-retained prostheses (OR&#61;2.439, 95%CI&#61;1.241-4.795) and nonplatform switch design (OR&#61;2.055, 95%CI&#61;1.167-3.619) were identified as weak risk factors. Horizontal deviation (OR&#61;4.177, 95%CI&#61;2.265-7.703) was a moderate risk factor. Vertical deviation (OR&#61;10.107, 95%CI&#61;5.280-19.347) and implants located in the mandibular molar region (OR&#61;10.427, 95%CI&#61;1.176-92.461) were considered high risk factors. Implants in the molar region, cement retained, non-platform switch design, and poor three-dimensional implant positioning are identified as significant risk factors for peri-implant bone loss.

Longitudinal Observation of Micromotion upon Loading of Implant-Abutment Connection.

While technological advances have made implants a good treatment option with a good long-term prognosis, peri-implantitis, which results in alveolar bone resorption around implants, has been observed in some cases. Micromotion at the implant abutment connection can cause peri-implantitis. However, the temporal progression of micromotion upon loading remains unclear. Therefore, we aimed to longitudinally measure micromotion upon loading application on an implant. Implants with Morse-tapered connections were prepared. Custom titanium abutments were fabricated and tightened onto implant bodies at 35 N. A 100 N vertical load was applied for 200,000 cycles. Micromotion was measured when the load was applied, as was the total implant length and removal torque before and after loading. The micromotion was measured from the position data of the jig of the testing machine during loading. The average removal torque was 30.67 N after 10 min of tightening and 27.95 N after loading, indicating a decrease due to loading. The implant length reduced by 3.6 μm under the load. The average micromotion was 0.018 mm at 2 cycles, 0.016 mm at 100,000 cycles, and 0.0157 mm at 200,000 cycles, indicating implant length reduction under the load but not reaching 0. The micromotion between the implant and abutment under a cyclic load decreased over time but did not completely cease. These results highlight the relationship between micromotion and loading, underscoring the importance of careful monitoring and management to mitigate potential complications, such as peri-implantitis, and ensure optimal performance and durability of the implant.

Experimental study on implant-abutment locking force and abutment subsidence in a pure Morse taper connection implant system.

This test aimed to investigate the factors affecting the locking force between the implant and abutment and the amount of abutment subsidence in pure Morse taper connection implant systems. With reference to the Bicon implant abutment connection design, different types of implant specimens and their corresponding types of abutments were fabricated. The implant-abutment locking taper was uniformly 1.5°. The locking depths were 1.0, 2.0, and 3.0 mm. The diameters of the locking column were 2.5, 3.0, and 3.5 mm. The thicknesses of the outer wall of the implant were 0.15 and 0.30 mm. The loading forces of the testing machine were 200, 300, and 400 N. At least 10 specimens of each group of implant-abutment were used. All specimens were loaded in the same manner using a universal testing machine (finger pressure + specified loading force, five times). The total height of the implant-abutment was measured before finger pressure, after finger pressure, and after the testing machine was loaded for five times to calculate the amount of sinking of the abutment. Finally, the implant and abutment were pulled apart using the universal testing machine, and the subluxation force was observed and recorded. The test loading force, locking depth, and locking post diameter had an effect on the implant-abutment locking force and abutment subsidence. The implant-abutment locking force increased with the increase in the test loading force, locking depth, and locking post diameter (R=0.963, 0.607, and 0.372, respectively), with the test loading force having the most significant effect. Abutment subsidence increased with the increase in test loading force (R=0.645) and decreased with the increase in locking depth and locking post diameter (R=-0.807 and -0.280, respectively), with locking depth having the most significant effect on abutment subsidence. No significant correlation was found between the thickness of the outer wall of the implant and the change in the magnitude of the implant-abutment locking force. However, an increase in the thickness of the outer wall of the implant decreased the amount of abutment subsidence, which was inversely correlated. The locking force of the implant-abutment can be increased by adjusting the design of the pure Morse taper connection implant⁃abutment connection, increasing the locking depth and locking post diameter, and increasing the amount and number of times the abutment is loaded during seating. Problems, such as loosening or detachment of the abutment, can be reduced. The recommended abutment to be loaded should be no less than five times during seating to prevent the abutment from sinking and causing changes in the occlusal relationship in the later stages. Preliminary occlusal adjustments should only be conducted in the early stages of the use of temporary restorations, and final restorations and occlusal adjustments are recommended to be performed after using the abutment for a period of time.

Rotational Load Fatigue Performance of a One-Size Implant- Abutment Connection System.

To investigate the rotational load fatigue performance of different implant diameters and abutment platforms of a one-size implant-abutment (OSIA) connection system. Narrow-, regular-, and wide-diameter implants were tested with regular base (RB/WB) abutments of an OSIA system (BLX, Straumann). Wide-diameter implants (WDIs) were also tested with wide base (WB) abutments. This resulted in four test groups: (1) narrow-diameter implants (NDIs; 3.5 mm) with RB/WB abutments, (2) regular-diameter implants (RDIs; 4.0 mm) with RB/WB abutments, (3) WDIs (5.0 mm) with RB/WB abutments, and (4) WDIs (5.0 mm) with WB abutments. Each group tested five of their respective implants (n = 5). A rotational load fatigue machine applied a sinusoidally varying stress at a 45-degree angle, producing an effective bending moment of 35 Ncm at a frequency of 10 Hz in 20°C air. The number of cycles to failure was recorded, and the results were evaluated using two-way ANOVA. Failed specimens were examined with a scanning electron microscope (SEM) to evaluate the failure mode. Pristine specimens were sectioned to examine the implant-abutment connection. All specimens in three of the test groups with RB/WB abutments failed within the range of 558,750 cycles to 4,497,619 cycles, while the WDI-WB test group reached the upper limit of 5 million cycles without failure. A significant difference was found between abutment platforms (P < .001). There were no significant differences found for implant diameters (P = .857). However, with a greater implant diameter, implant fracture was less common, and the failure location was more coronal. It was consistently at the implant platform level for the abutment and at the screw neck. For WDIs, WB abutments exhibited superior fatigue performance compared to RB/WB abutments and would be preferred in situations of high mechanical risk. Increasing the implant diameter, when used with RB/WB abutments, did not improve fatigue performance due to the one-size prosthetic connection; however, failures were less catastrophic and coronally located, which may be advantageous in managing failures.

A New Full Digital Workflow for Fixed Prosthetic Rehabilitation of Full-Arch Edentulism Using the All-on-4 Concept.

(1) Background: Recent digital workflows are being developed for full-arch rehabilitations supported by implants with immediate function. The purpose of this case series is to describe a new digital workflow for the All-on-4 concept. (2) Methods: The patients were rehabilitated using the All-on-4 concept with a digital workflow including computerized tomography scanning, intra-oral scanning, and CAD-CAM production of the temporary prosthesis, with the 3D printing of stackable guides (base guide, implant guide, and prosthetic guide). The passive fit of the prostheses and the time to perform the rehabilitations were evaluated. (3) Results: The digital workflow allowed for predictable bone reduction, the insertion of implants with immediate function, and the connection of an implant-supported prosthesis with immediate loading. The time registered to perform the full-arch rehabilitations (implant insertion, abutment connection, prosthesis connection) was below 2 hours and 30 min. No passive fit issues were noted. (4) Conclusions: within the limitation of this case series, the digital workflow applied to the All-on-4 concept using stackable base-, implant-, and prosthetic guides constitutes a potential alternative with decreased time for the procedure without prejudice of the outcome.

Maxillary sinus floor augmentation with autogenous bone graft compared with composite grafts: A one-year single-blinded randomized controlled trial.

The objective was to assess the one year implant treatment outcome and patient-related outcome measures (PROMs) following maxillary sinus floor augmentation (MSFA) with autogenous bone graft (ABG) from the zygomatic buttress (control) compared with 1:1 mixture of ABG and anorganic porcine bone mineral (APBM) (Test I) or biphasic bone graft material (BBGM) (Test II). Sixty healthy patients (34 females, 26 males) were randomly allocated to either control or test groups. Outcome measures included survival of suprastructures and implants, implant stability quotient, health status of peri-implant tissue, peri-implant marginal bone loss, frequency of complications, and PROMs using Oral Health Impact Profile-14 combined with questionnaire assessing patient perception of peri-implant soft tissue, prosthetic solution, implant function, and implant treatment outcome using visual analogue scale. Mean differences were expressed with standard deviation and 95% confidence interval. Level of significance was .05. All suprastructures and implants were well-functioning after one year of functional implant loading. There was no significant difference between control and test groups in any of the applied outcome measures. The implant stability significantly increased from implant placement to abutment connection within all groups (p < .001). High patient satisfaction and significant improvement in oral health-related quality of life was also reported within all groups. This study demonstrates that MSFA with composite grafts containing minimal amounts of ABG reveals comparable implant treatment outcomes as compared with ABG alone, after one year of functional implant loading. Extensive ABG harvesting in conjunction with MSFA therefore seems not to be needed.

Effect of implant‒abutment connections on abutment screw loosening: An in vitro study.

The widespread use of dental implants as a predictable treatment choice has drawn attention to their complications as a major challenge despite their high clinical success rates. In this context, loosening of the abutment screw in posterior single crowns is the most common problem; the use of adequate preload and proper anti-rotational features at implant‒abutment interface appear to be two main solutions to such a problem. The present study evaluated the effect of implant‒abutment connections in four different implant systems before and after cyclic loading. Intra-Lock, Dentis, Xive, and Dio implant systems were used in this study. Each system underwent one million cycles of dynamic forces eight times with a magnitude of 110 N. For each specimen after tightening the screw with a torque of 32 Ncm, the detorque values were measured and recorded by a digital torquemeter after and before cyclic loading. Data were analyzed by Kolmogorov-Smirnov, Levene's, one-way ANOVA, and post hoc Tukey tests. Initial detorque values between the study groups showed significant differences (P<0.0001). Pairwise comparisons showed significantly lower primary detorque values in the Dentis system compared to the three other systems (P<0.0001). After cyclic loading, significant differences were observed between the study groups (P<0.0001). Pairwise comparisons of the groups showed significant differences between all the systems after loading. The type of implant‒abutment connection is an essential factor influencing the amount of abutment screw loosening.

Immediate rehabilitation of severely atrophic maxillae using conventional and extended length subcrestal angulated (ELSA) implants: A retrospective analysis of 187 implants in 33 patients with up to three years of function.

The purpose of this study was to evaluate and determine clinical outcomes and survival rates of straight and extended length subcrestal angulated (ELSA) implants (20-24mm lengths) placed for immediate (up to 72h post-operative) or delayed rehabilitation (4 months post-operative) of severely atrophic maxillae. Prosthetic treatment consisted of interim and definitive implant-supported fixed implant-supported prostheses with up to 3 years of function. A retrospective analysis was conducted of 38 patients (five dropped out; final total was 33), treated between 2017 and 2019 in a private practice. Extended length subcrestal angulated (ELSA) implants and conventional endosseous straight implants (Southern Implants, Irene, South Africa) with (fixed) full arch prostheses were used to restore patients with edentulous maxillae immediately (within 72hs) or delayed (4 months). ELSA implants have subcrestal angulations of 24° and 36° of the restorative platforms, external hexagon crestal anti-rotation abutment connections, and lengths between 18 and 26mm. Implant loading was determined by implant insertion torque values (as determined on the surgical units); 120Ncm was the threshold level for immediate loading. Clinical and radiographic examinations were done that recorded the clinical outcomes of implants and prostheses. SPSS was used to process the data. Thirty-three patients and 187 implants were included with follow-up periods of at least 12 months (range 12-36 months). The mean age of the study population was 62.6 ± 8.4 years old (at the time of implant placement). Thirty-three patients (86.8%) were followed for 12 months; 13 patients (39.4%) were followed for 24-35 months; 9 patients (27.3%) were followed for 36 months. In total, 13 implants in six patients failed secondary to sinus infections. Mean bone levels (MBLs) were respectively: 0.88±2.12mm at loading, -1.53±2.03mm at 12 months, -2.26±1.45mm at 24 months, and -2.54±1.46mm at 36 months. The ELSA implants showed significantly lower (p = 0.014) MBL at 36 months than did the conventional implants. One hundred thirty-seven implants were placed and loaded within 72h; 50 implants were placed and loaded 4 months post placement. The combined implant survival rates were 93.0% at 12 months, 91.1% at 24 months, and 100% at 36 months. The ELSA implants showed significantly lower (p = 0.014) MBLs at 36 months when compared to the conventional implants. The results of this retrospective clinical chart review indicated that the use of ELSA implants placed into anterior maxillae and nasal crests with accentuated distal tilts (>30°) and simultaneous sinus augmentation provided favorable outcomes for prosthetic rehabilitation in patients with severe atrophic maxillae. ELSA implants placed with simultaneous sinus augmentation are an alternative option to zygomatic implants (ZI) when immediate loading is prescribed. Sinus infections were thought to be the proximate causes of all implant failures. Further long-term clinical studies are warranted with larger patient populations.