Internal fit and marginal adaptation of all-ceramic implant-supported hybrid abutment crowns with custom-milled screw-channels on Titanium-base: in-vitro study.

BACKGROUND: Advancements in digital dentistry helped in custom-milling screw-channels in implant-supported restorations; however, the fit of these restorations is still unclear especially for contemporary computer aided designing/computer aided manufacturing (CAD/CAM) materials. This study aimed to compare the internal and marginal fit of Ultra translucent multilayered zirconia versus lithium disilicate implant-supported hybrid abutment crowns (HACs) constructed with custom-milled screw-channels on Titanium-base. MATERIALS AND METHODS: A total of 24 HACs with custom-milled screw-channels were constructed from lithium disilicate (Group LDS) and Ultra translucent multilayered zirconia (Group UT) using digital workflow (n = 12). The internal and marginal gaps of HACs on their corresponding Titanium-bases were assessed using replica technique and stereomicroscope, respectively. After testing for normality, quantitative data were expressed as mean and standard deviation and compared using independent t-test at a level of significance (P ≤ 0.05). RESULTS: There was no statistically significant difference between Group LDS and Group UT in terms of marginal and internal fit. The internal and marginal gaps in both groups were within the accepted values reported in literature. CONCLUSIONS: UT and LDS HACs with custom-milled screw-channels demonstrated comparable and acceptable internal fit and marginal adaptations to Ti-base, which lied within the range reported in literature.

Effect of polishing process on torque loss ratio and microgap of selective laser melting abutment: an in vitro study.

BACKGROUND: The purpose of this in vitro study was to investigate the effect of polishing post-treatment process on the torque loss ratio and microgap of Selective Laser Melting (SLM) abutments before and after mechanical cycling test through improving the surface roughness of the implant-abutment interface. MATERIALS AND METHODS: Forty SLM abutments were fabricated, with 20 underwent minor back-cutting, designated as polishing, in the implant-abutment interface. The abutments were divided into three groups: SLM abutments (group A), original abutments (group B), and polished SLM abutments (group C), each containing 20 abutments. Surface roughness was evaluated using a laser microscope. Implant-abutment specimens were subjected to mechanical cycling test, and disassembly torque values were measured before and after. Scanning electron microscope (SEM) was used to measure microgap after longitudinal sectioning of specimens. Correlation between surface roughness, torque loss ratio, and microgap were evaluated. LSD's test and Tamhane's T2 comparison were used to analyze the data (α = 0.05). RESULTS: The Sz value of polished SLM abutments (6.86 ± 0.64 µm) demonstrated a significant reduction compared to SLM abutments (26.52 ± 7.12 µm). The torque loss ratio of polished SLM abutments (24.16%) was significantly lower than SLM abutments (58.26%), while no statistically significant difference that original abutments (18.23%). The implant-abutment microgap of polished SLM abutments (2.38 ± 1.39 µm) was significantly lower than SLM abutments (8.69 ± 5.30 µm), and this difference was not statistically significant with original abutments (1.87 ± 0.81 µm). A significant positive correlation was identified between Sz values and the ratio of torque loss after cycling test (r = 0.903, P < 0.01), as well as Sz values and the microgap for all specimens in SLM abutments and polished SLM abutments (r = 0.800, P < 0.01). CONCLUSION: The findings of this study indicated that the polishing step of minor back-cutting can lead to a notable improvement in the roughness of SLM abutments interface, which subsequently optimized the implant-abutment fit. It can be seen that the application of minor back-cutting method has advanced the clinical use of SLM abutments.

Comparison of misfit and roughness of CAD-CAM ZrO, selective laser sintered CoCr and preformed Ti implant abutment crowns.

BACKGROUND: Marginal misfit and surface roughness of customized implant abutments is critical for restorative success. However, little is known about the comparison of misfit and surface roughness of CAD-CAM Zirconium oxide (ZrO), selective laser melting (SLM) Cobalt Chrome (CoCr) and preformed abutments. The aim of the study is to investigate the relation of misfit and micro-roughness of selective laser melting (SLM), preformed and CAD-CAM implant abutments. METHODS: Thirty internal connection, endosseous dental implants (Ø 4.0 mm x 10 mm, Dentium) were mounted in Polymethyl methacrylate vertically. Ten preformed Titanium alloy (Ti) abutments with 1 mm soft tissue height and Ø 4.5 mm were included as controls. Ten each of Y-TZP and SLM-CoCr, abutment/crowns were fabricated using CAD-CAM milling (CAD-CAM-ZrO) and SLM techniques. Surface micro-roughness (Ra) of the fabricated implant abutment/crown was evaluated with a 3D optical non-contact microscope. All implant restorations were torqued to implants (30 Ncm) using a Tohnichi BTGE digital torque gauge and were analyzed with Bruker micro-CT (Skyscan 1173) to detect micro-gaps at pre-selected points at implant abutment interface. The Ra and misfit data were compared using ANOVA, Tukey-Kramer, Kruskal-Wallis test and Pearson correlation (p < 0.05). RESULTS: Mean Ra among SLM CoCr abutments [0.88 (0.09) µm] were lower than CAD-CAM-ZrO and higher than preformed Ti abutments. Horizontal misfit among SLM-CoCr [45.43 (9.41) µm] and preformed Ti [36.87 (13.23) µm] abutments was not statistically different (p > 0.05). Misfit was significantly higher in Y-TZP samples compared to SLM-CoCr (p = 0.031) and preformed Ti abutments (p = 0.01). Preformed Ti abutments showed significantly lower misfit compared to SLM-CoCr abutments (p = 0.01). A positive linear correlation was observed between the surface roughness (Ra) and vertical misfit (r = 0.61, p < 0.05). CONCLUSION: SLM CoCr abutments showed rough surface compared to preformed Ti abutments, while horizontal misfit was comparable among SLM-CoCr and preformed abutments. Misfit was significantly greater in Y-TZP abutments, compared to SLM and preformed abutments. SLM abutment fabrication technique needs further improvement to provide better fit and surface topography.

Clinical outcomes of single implant supported crowns utilising the titanium base abutment: A 7.5-year prospective cohort study.

OBJECTIVE: To assess radiographic, clinical and patient-reported outcomes of single zirconia implant-supported crowns on titanium base abutments (TBA) over a 7.5-year period. METHODS: Twenty-four patients received bone-level titanium implants and screw-retained zirconia implant crowns utilising TBA. Marginal bone level (MBL), clinical parameters (probing depth-PD, bleeding on probing-BoP, plaque control record-PCR), technical complications (USPHS criteria) and patient satisfaction were assessed at crown delivery (baseline), 1 year (FU-1) and at 7.5 years (FU-7.5) of follow-up. RESULTS: Eighteen patients were available for re-examination at 7.5 years. The mean MBL at FU-7.5 (0.35 ± 0.20mm) did not significantly change compared to baseline (0.54 ± 0.39, p=.352) and to FU-1 (0.54 ± 0.45mm, p=0.524). From baseline to 7.5 years, the mean PD increased significantly, from 3.0 ± 0.6mm to 3.7 ± 0.8mm (p=0.005). However, BoP and PCR did not significantly change; (BOP: from 27.1 ± 20.7% to 25.0 ± 20.0%, p=0.498; PCR: from 11.1 ± 21.2% to 25.0 ± 25.1%, p=0.100). Nine patients presented with more than one bleeding site. This denoted a peri-implant mucositis prevalence of 50%, whilst none of the implants presented peri-implantitis. One incidence of minor and major ceramic chipping were reported on 2 out of the 18 crowns, resulting in a prosthetic survival rate of 94.4%. Seventeen patients were highly satisfied with their result. CONCLUSION: Single implant-supported zirconia crowns on TBA displayed: (i) minor number of technical complications, (ii) high prosthetic survival rate, (iii) stable marginal bone level and (iv) high patient satisfaction at 7.5 years. CLINICAL IMPLICATIONS: Titanium base abutments despite their high use in clinical practice, lacked medium- and long-term studies. The presented findings highlight their clinical performance at 7.5 years as they display satisfying radiographic, clinical and patient-related outcomes. TBA appear to be a suitable abutment choice for medium-term implant-supported restorations.

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.

Effect of Implant-Abutment Connection and Abutment Angulations on Peri-implant Stress Levels: A Finite Element Analysis Study.

INTRODUCTION: Placement of an implant in the maxillary anterior region is challenging due to the angulation of bone in this area. Angled abutments may be used to achieve proper restorative contours. The present study was undertaken to examine and compare the stress levels of implants in the maxillary anterior region having different types of internal connections and different abutment angulations. MATERIAL AND METHODS: Implants with three types of abutment connections, internal conical, Morse taper, and internal hex, were modeled using SolidWorks software. Three abutment angulations of 0, 15, and 30 degrees were used for each type of implant. A 100 N axial load was applied to the implants, and the stresses on the implant, abutment, and bone were analyzed by finite element analysis. RESULTS: Among the straight abutments, the most stress was in model 3A (62.60 MPa). The stress value among angled abutments was highest with 30-degree angled abutments. The value was highest in model 3C (94.83 MPa). Internal hex connection showed the highest stress levels in all degrees of angulation of the abutment, and Morse taper connection showed the least amount of stress in all three abutment angles. The most stress concentration was seen in the cortical bone on the buccal surface in the implant-abutment junction. CONCLUSION: The Morse taper design of implant exhibited the least-highest stress levels on the alveolar bone. The stress levels increased with the increasing angulation of the implant or implant-abutment connection.

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.

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

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Mechanical strength of stock and custom abutments as original and aftermarket components after thermomechanical aging.

OBJECTIVES: The study aimed to assess the impact on the mechanical strength and failure patterns of implant-abutment complexes of choosing different abutment types, designs and manufacturers, aiding in selecting the optimal restorative solution. Stock and custom abutments from original and aftermarket suppliers were subjected to thermomechanical aging. MATERIAL AND METHODS: Stock and custom abutments from the implant manufacturer (original) and a aftermarket supplier (nonoriginal) were connected to identical implants with internal connection. Custom abutments were designed in a typical molar and premolar design, manufactured using the workflow from the respective suppliers. A total of 90 implants (4 mm diameter, 3.4 mm platform, 13 mm length) equally divided across 6 groups (three designs, two manufacturers) underwent thermo-mechanical aging according to three different regimes, simulating five (n = 30) or 10 years (n = 30) of clinical function, or unaged control (n = 30). Subsequently, all samples were tested to failure. RESULTS: During aging, no failures occurred. The mean strength at failure was 1009N ± 171, showing significant differences between original and nonoriginal abutments overall (-230N ± 27.1, p < .001), and within each abutment type (p = .000), favoring original abutments. Aging did not significantly affect the failure load, while the type of abutment and manufacturer did, favoring original and custom-designed abutments. The most common failure was implant bending or deformation, significantly differing between original and nonoriginal abutments and screws. All failure tests resulted in clinically unsalvageable implants and abutments. CONCLUSIONS: Within the limitations of this study, original abutments exhibited a higher mechanical strength compared to the nonoriginal alternative, regardless of the amount of simulated clinical use. Similarly, custom abutments showed higher mechanical strength compared to stock abutments. However, mechanical strength in all abutments tested was higher than average chewing forces reported in literature, thus components tested in this study can be expected to perform equally well in clinical situations without excessive force.

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.

The influence of implant depth, abutment height and mucosal phenotype on peri­implant bone levels: A 2-year clinical trial.

OBJECTIVES: To evaluate the bone changes around equicrestal and subcrestal implants, analyzing the effect of abutment height [short abutments (SA < 2 mm) and long abutments (LA > 2 mm)] and the three components of the peri­implant soft-tissue phenotype. METHODS: Twenty-six patients received 71 implants that were placed according to supracrestal tissue height (STH) in an equicrestal (n = 17), shallow subcrestal ≈1 mm (n = 33), or deep subcrestal ≈2 mm (n = 21) position. After 3 months of healing, rehabilitation was completed using metal-ceramic crowns on multi-unit abutments of 1.5 mm, 2.5 mm, or 3.5 mm in height, depending on the prosthetic space and STH. Longitudinal clinical parameters (STH, mucosal thickness, and keratinized mucosa width) and radiographic data [bone remodelling and marginal bone loss (MBL)] were collected at 3, 6, 12, and 24 months postsurgery. RESULTS: The gain in STH was significantly greater around the implants placed in a subcrestal ≈2 mm position. After 2 years, the mean change in bone remodelling in the SA group was significantly greater than in the LA group. According to the multiple linear regression, bone remodelling depends primarily on abutment height (ß = -0.43), followed by crestal position (ß = 0.34), and keratinized mucosa width (ß = -0.22), while MBL depends on abutment height (ß = -0.37), and the patient's age (ß = -0.36). CONCLUSIONS: Implants placed in an equicrestal or subcrestal ≈1 mm position with LA undergo less bone remodelling, while the lowest level of MBL occurs in subcrestal ≈2 mm implants with LA. Differing soft-tissue thicknesses combined with the use of either SA or LA produced significant intergroup differences in bone remodelling and MBL. CLINICAL SIGNIFICANCE: Abutment height is the most powerful predictor variable affecting bone remodelling and MBL. Depending on the dimensions of the peri­implant soft-tissue phenotype, placing the implants subcrestally may also be a viable option to decrease bone remodelling and, consequently, reduce MBL. CLINICAL TRIAL REGISTRATION: identification number: NCT05670340.

The effect of thermomechanical aging on the fracture resistance of additively and subtractively manufactured polyetheretherketone abutments.

OBJECTIVES: To evaluate the fracture resistance (FR) of polyetheretherketone (PEEK) abutments produced by additive and subtractive methods compared to milled zirconia abutments. METHODS: Custom abutments were designed on Ti-base abutments and produced from three different materials, namely additively manufactured PEEK (PEEK-AM), subtractively manufactured PEEK (PEEK-SM), and zirconia (N = 60). PEEK-AM abutments were printed using PEEK filaments (VESTAKEEP®i4 3DF-T, Evonik Industries AG) on a M150 Medical 3D Printer (ORION AM) by fused filament fabrication (FFF). All surface treatments were carried out according to the manufacturer's instructions. All abutments were cemented on Ti-bases with hybrid abutment cement and then restored with milled zirconia crowns. Each subgroup was divided into non-aged and aged subgroups (n = 10). The aged groups were subjected to thermomechanical aging (49 N, 5-55 °C, 1.2 million cycles). FR tests were performed by using an universal testing machine. Data were statistically analyzed with one-way and two-way ANOVA and t-test. RESULTS: The survival rate of the specimens after aging was determined as 100%. It was found that both the material and aging had a significant effect on the FR (p<.001). There was a statistical difference among the fracture values of the groups (p<.001). In both the aged and non-aged groups, PEEK-AM showed the statistically lowest FR, while the highest FR was seen in the zirconia group, which was significantly higher than the PEEK-SM (p<.001). CONCLUSION: Hybrid abutments were successfully manufactured, and extrusion-based processed PEEK seems to be a good alternative to subtractive processed PEEK. However, since subtractive manufacturing still appears to be superior, further developments in additive manufacturing are needed to further improve the quality of 3D-printed PEEK parts, especially in terms of accuracy and bonding between adjacent layers. CLINICAL SIGNIFICANCE: Additively manufactured PEEK abutments have the potential to be an alternative for implant-supported restorations in the posterior region.

Management of Broken Screw Inside Implant Screw Channel: A Case Report.

RATIONALE: This case report outlines a novel prosthodontic approach for managing a broken screw inside an implant screw channel, emphasising the importance of innovative solutions in implant dentistry. PATIENT CONCERNS: A 57-year-old male patient sought restoration for implant-supported crowns (#46 and #47). A broken screw inside the implant screw channel posed a significant concern for both the patient and the dental team. TREATMENT: Utilising an impression pickup technique of the inner surface of the implant body, a custom titanium abutment was fabricated in the laboratory and restoration was successfully replaced. A follow-up of 6 months was performed, ensuring optimal function and patient satisfaction. OUTCOME: The custom titanium abutment with a zirconia crown was placed, leading to a successful restoration. The patient reported no discomfort, demonstrating improved function and aesthetics. TAKEAWAY LESSON: This case highlights the effectiveness of tailored prosthodontic interventions in addressing complex implant-related complications.

Influence of toothbrushing methods on tightening torque with healing abutments of different lengths: An in vitro study.

STATEMENT OF PROBLEM: Early tightening torque at the implant-healing abutment interface is a recognized concern in implant treatment. However, little is known regarding the effects of toothbrushing methods on the interface established between the implant and healing abutments of different heights. PURPOSE: The purpose of this in vitro study was to evaluate the effect of different toothbrushing methods on tightening torque for healing abutments of different heights. MATERIAL AND METHODS: A total of 60 implants (Bilimplant; Proimtech) were embedded in epoxy resin blocks. The following 6 test groups were established: healing abutments with manual toothbrush group (Oral B Pro Expert All in one; Oral B) and 4 mm height (MTB-4, (which served as the control); 6 mm height (MTB-6, which served as the control); sonic toothbrush group (Philips Sonicare 3100 Series; Philips Oral Healthcare) and 4 mm height (S-4); 6 mm height (S-6); oscillating/rotating toothbrush group (Oral B Smart 6 6000N; Oral B) and 4 mm height (OR-4) and 6 mm height (OR-6). Each specimen was tightened to 15 Ncm and brushed. The digital torque meter (Cap Torque Tester Series TT01; Mark10) was used to calculate the reverse torque values. RESULTS: The highest torque loss value in the average torque losses in the test groups was 1.3 (OR-6); the lowest was 0.3 (S-4). While a significant difference was found between groups S-4 and S-6 (P=.018), no statistically significant difference was found among the other groups (P>.05). CONCLUSIONS: Torque loss was greater in the healing abutment with a height of 6 mm and with the oscillatory and rotational brushing method.

Comparative Analysis of Internal Tapered Implant-Abutment Connections: Evaluating the Morse Effect.

The purpose of the present study was to evaluate the Morse effect of different internal tapered implant-abutment connections (ITCs) using a pullout test. Implants with different ITCs were selected: Short (Bicon, USA), G1; Novo Colosso (Medens, Brazil), G2; Epkut (SIN, Brazil), G3; Strong SW (SIN, Brazil), G4; Flash (Conexão, Brazil), G5 and Bone Level (Straumann, Switzerland), G6. The respective computer-aided design (CAD) files were loaded into the analysis software to measure each ITC's taper angle and implant-abutment contact area. Six implants from each group were embedded in acrylic resin blocks, and the respective universal abutments were fixed using a mallet (G1) or by applying 20 Ncm of torque (G2 to G6). After 10 minutes, each abutment's retention screw was removed, and the force necessary for abutment rupture was recorded using a universal testing machine at a crosshead speed of 0.5 mm/min. The groups were compared using a one-way analysis of variance and Tukey's test. Spearman's correlation was used to check the correlation of the taper angle and contacting area with the pullout strength. G1, a no-screw abutment with a 3° taper, and G2, a 10° tapered abutment tightened by 20 Ncm, presented the highest pullout strength (P < .05). The increased taper angle of G4, compared to G3, reduced the Morse effect despite their similar implant-abutment contacting areas (P < .05). The G5 and G6 abutments loosened after screw removal and did not exhibit pullout resistance. The closer the tapered angle (r = -.958) and the higher the implant-abutment contact area (r = .880), the higher the pullout strength (P < .001). Within the limits of this study, the Morse effect is different among tapered implant-abutment connections. The closer the tapered angle and the higher the interface area, the higher the Morse effect between the abutment and the implant.

Longevity of different abutments placed on narrow diameter implants: Assessment of structural damage and loosening.

OBJECTIVES: To evaluate structural damage and loosening of abutments placed on narrow diameter implants after cyclic fatigue. METHODS: Sixty Morse taper narrow diameter implants (Neodent, Brazil) received two types of abutments (1PA- one-piece abutment or 2PA- two-piece abutment), which were randomly divided into 3 fatigue experiments (n = 10). The implants were placed into a customized supporting holder and a software-assisted digital torque wrench secured the manufacturer recommended torque for each abutment. Cone beam computed tomography (CBCT) scans were acquired, before and after fatigue, and post-processed (software e-Vol DX) to assess damage and abutment displacement. The boundary fatigue method was adapted to use 2 × 106 cycles, 2 Hz of frequency and constant peak load of 80 N (first experiment) that varied according to the failure rate of previous specimens (second and third experiments). Failure was evaluated using CBCT scans and removal torque values. Data were used to estimate long-term torque degradation, probability of failure and Weibull modulus (software ALTA PRO9). RESULTS: All 2PA specimens became loosen independently of the applied fatigue load, and structural bending was observed in 14 abutments. Eight 1PA got loosen during the fatigue experiment. The Weibull analysis showed a lower modulus (m = 1.0; 0.7, 1.4) for 1PA than for 2PA (m = 2.6; 2, 3.4) resulting in longer predicted lifetimes and slower torque degradation for 1PA than for 2PA specimens. SIGNIFICANCE: 1PA showed greater long-term survival probability than 2PA. Predicting the lifetime and mechanical behavior of implant-abutment systems are useful information to clinicians during the decision-making process of oral rehabilitations.

Effect of laser-microtextured abutments on peri-implant outcomes: a systematic review and meta-analysis.

OBJECTIVES: To evaluate the potential of laser-microtextured abutments (LMAs) compared to machined abutments (MAs) in peri-implant clinical and radiographic outcomes. MATERIALS AND METHODS: Eligible studies consisted of randomized clinical trials (RCTs) retrieved from MEDLINE, Web of Science, Scopus, and Embase databases. The study adhered to the PRISMA statement, and the protocol was registered at the PROSPERO (registration number CRD42023443112). The risk of bias was evaluated according to version 2 of the Cochrane risk of bias tool (RoB 2). Meta-analyses were performed using random effect models. Afterward, the GRADE approach was used to determine the certainty of evidence. RESULTS: Four RCTs were included from a total of 2,876 studies. LMAs had lower peri-implant sulcus depth at 6-8 weeks (WMD: -0.69 mm; 95% CI: -0.97, -0.40; p = 0.15, I2 = 53%) and at one year (WMD: -0.75 mm; 95% CI: -1.41, -0.09; p = 0.09, I2 = 65%), but the certainty of evidence was low. In addition, the marginal bone loss favored the LMAs group (WMD: -0.29 mm; 95% CI: -0.36, -0.21; p = 0.69, I2 = 0%) with moderate evidence. There were fewer sites with bleeding on probing in the LMAs group (WMD: -1.10; 95% CI: -1.43, -0.77; p = 0.88, i2 = 0%). There was no statistical difference between groups for the modified gingival index and modified plaque index. Furthermore, all studies were classified as having some concerns risk of bias. CONCLUSIONS: There was low to moderate certainty evidence that LMAs can favor peri-implant clinical and radiographic parameters compared to MAs. CLINICAL RELEVANCE: Laser-microtextured abutments may benefit peri-implant clinical and radiographic outcomes.

Clinical efficacy of a two-piece abutment conforming to the concept of one abutment one time in the posterior region: A clinical pilot study.

OBJECTIVES: To assess the impact of a two-piece abutment workflow on enhancing the stability of the alveolar bone and gingiva surrounding the dental implant, and to determine the level of patient satisfaction. MATERIALS AND METHODS: A total of 48 patients with dentition defect in the posterior region were included and divided into two groups: the two-piece abutment workflow (TAW) and the sealing screw with submerged healing workflow (SHW). Marginal bone level (MBL), soft tissue indicators, oral hygiene indicators, and patient satisfaction were assessed and recorded partially at 0, 3, 6, and 12 months after surgery. The primary outcome was the change of MBL in different time periods. A generalized linear mixed model (GLMM) was used to take into account the correlated nature of the data, and adjust for potential confounding factors within inter-group differences. RESULTS: The survival rate of implants and prosthesis reached 100% at 12-month follow-up, with an average decrease of 0.25 mm (SD 0.23 mm) of MBL in the TAW group and 0.48 mm (SD 0.45 mm) in the SHW group. The change of MBL in the TAW group (0.15 ± 0.31 mm) was significantly lower than the SHW group (0.41 ± 0.41 mm) through the analysis of GLMM within 6 months, while no significance was found in 12 months. Moreover, less gingival pain and oppression during prosthesis loading, and less time consumption overall duration were showed in the TAW group through Visual Analogue Scale (VAS, p < 0.05). CONCLUSIONS: Within a 6-month period, the two-piece abutment workflow showed superior efficacy in preserving the integrity of the marginal bone level. Furthermore, it streamlined treatment procedures and mitigated discomfort, hence increasing patient satisfaction.

Transfer of Guided Emergence Profile Developed Using Customized Provisional Implant Restoration and Cementation Using an Abutment Replica Technique: A Case Report.

The long-term success of dental implants depends not only upon implant osseointegration, but also on the surrounding soft tissue health and profile. An ideal emergence profile contributes to the aesthetics of an implant restoration. It maintains long-term implant health by preventing potential food accumulation and forming a barrier against bacterial ingress. This article describes a method for obtaining an impression of implants that will capture the custom guided peri-implant soft tissue contours accurately, thus contributing to a final restoration with favorable aesthetics. We also describe a technique for reducing excess cement in a cement retained implant crown, thereby contributing to the health of the peri-implant tissues.

Material and abutment selection for CAD/CAM implant-supported fixed dental prostheses in partially edentulous patients - A narrative review.

Restorative material selection has become increasingly challenging due to the speed of new developments in the field of dental material science. The present narrative review gives an overview of the current indications for implant abutments and restoration materials for provisional and definitive implant-supported fixed dental prostheses in partially edentulous patients. For single implant restorations, titanium base abutments for crowns are suggested as an alternative to the conventional stock- and customized abutments made out of metal or zirconia. They combine the mechanical stability of a metallic connection with the esthetic potential of ceramics. For multiple-unit restorations, conical titanium bases especially designed for bridges are recommended, to compensate for deviating implant insertion axes and angulations. Even though titanium base abutments with different geometries and heights are available, certain clinical scenarios still benefit from customized titanium abutments. Indications for the definitive material in fixed implant restorations depend on the region of tooth replacement. In the posterior (not esthetically critical) zone, ceramics such as zirconia (3-5-Ymol%) and lithium-disilicate are recommended to be used in a monolithic fashion. In the anterior sector, ceramic restorations may be buccally micro-veneered for an optimal esthetic appearance. Lithium-disilicate is only recommended for single-crowns, while zirconia (3-5-Ymol%) is also recommended for multiple-unit and cantilever restorations. Attention must be given to the specific mechanical properties of different types of zirconia, as some feature reduced mechanical strengths and are therefore not indicated for all regions and restoration span lengths. Metal-ceramics remain an option, especially for cantilever restorations.