Sealing agent reduces formation of single and dual-species biofilms of Candida albicans and Enterococcus faecalis on screw joints at the abutment/implant interface

Anaerobic adhesives effect on counter-torque of abutment screws on implants with external hexagon and conical connections: An in vitro study

BACKGROUND

Abutment screw loosening is a common complication of implant supported prostheses, especially for single crowns. In engineering, anaerobic adhesives (AA) are used to provide chemical locking between screw surfaces, but their application in implantology remains unclear.

PURPOSE

The purpose of this article is to evaluate, in vitro, the effect of AA on counter-torque of abutment screws for cemented prosthesis on dental implants with external hexagon connection (EHC) and conical connection (CC).

MATERIALS AND METHODS

Sample was composed by 60 specimens, 30 dental implants with EHC and 30 with CC. Abutments (transmucosal 3 mm straight universal abutment) were installed without AA (control group) or with application of AA with two different adhesive strength: medium strength (LOCTITE® 242) and high strength (LOCTITE® 277). The specimens were subjected to mechanical cycling at 37°C, with a load setting of 133 N, a 1.3 Hz frequency, and 1 200 000 cycles. The abutments were removed, and the counter-torque values were registered. Screws and implants were inspected using a stereomicroscope to verify the presence of residual adhesive and damage the internal structures. The data were analyzed using descriptive statistics and comparison tests (p < 0.05).

RESULTS

Comparing to the torque of installation, the medium strength AA kept the counter-torque values for CC implants and the high strength AA kept the counter-torque for EHC implants and increased for CC implants. In the intergroup comparisons, control group presented significantly lower counter-torque values than other groups, both for EHC and CC implants. High strength AA presented similar results to medium strength AA in the EHC implants, but in the CC implants presented higher counter-torque values. Damage in threads was more frequent in the groups that received high strength AA.

CONCLUSION

The use of AA increased the counter-torque of abutment screws, both in implants with EHC and CC.

Microbiome and the inflammatory pathway in peri-implant health and disease with an updated review on treatment strategies

Crestal bone preservation around the dental implant for aesthetic and functional success is widely researched and documented over a decade. Several etiological factors were put forth for crestal bone loss; of which biofilm plays a major role. Biofilm is formed by the colonization of wide spectra of bacteria inhabited around dental implants. Bacterial adherence affects the regulators of bone growth and an early intervention preserves the peri-implant bone. Primary modes of therapy stated in early literature were either prevention or treatment of infection caused by biofilm. This narrative review overviews the microbiome during different stages of peri-implant health, the mechanism of bone destruction, and the expression of the biomarkers at each stage. Microbial contamination and the associated biomarkers varied depending on the stage of peri-implant infection. The comprehensive review helps in formulating a research plan, both in diagnostics and treatment aspects in improving peri-implant health.

Assessing Microleakage at 2 Different Implant-Healing Abutment Interfaces

OBJECTIVES

This study aimed to evaluate implants from different manufacturers and determine whether implant-healing abutment interface has a significant impact on implant seal.

METHODS

An air-injection pressure measurement test was performed on implants with either line-contact (modified TSIII [TSM] and Bone Level Tapered [BLT]) or partial face-contact (BlueDiamond [BD], SuperLine [SL], ISII, and UFII) interface design from 6 different manufacturers. Forty implants per implant type were analysed. Pressure data were evaluated with Kruskal-Wallis test and Dunn's post hoc analysis (statistical significance was set at P < .05).

RESULTS

BLT implants leaked when the mean pressure was increased to 199.9 kPa. The following implants showed mean leakage pressures of 182.9 (TSM), 157.4 (BD), 112.9 (SL), 101.8 (ISII), and 30.6 (UFII). There was a significant difference between line-contact and partial face-contact implants (P < .001).

CONCLUSIONS

The implant interface design has a significant impact on implant microbial leakage. Implants with a line-contact interface exhibited a higher resistance to leakage than those with partial face-contact.

Evaluation of sealing efficacy and removal convenience of sealing materials for implant abutment screw access holes

Background

Sealing materials are used to fill abutment screw access holes (SAH) to prevent microleakage and protect the central screws in oral implant restoration. However, thus far, no consensus has been reached on sealing material selection. In this study, a comparison of the sealing efficacy and removal convenience of different sealing materials for cement-retained implant restoration was conducted.

Methods

Various sealing materials were classified into five groups, namely, gutta-percha (GP), temporary restorative paste (TRP), vinyl polysiloxane (VPS), polytetrafluoroethylene (PTFE) tape, and onlay resin (OR), and 35 sets of analog-abutments were allocated into five groups of seven specimens. A sealing efficacy test was conducted using a modified dye-penetration method, in which a lower absorbance indicated better sealing efficacy. For the removal-convenience test, the materials were removed from each SAH after solidification, and the retrieval time was recorded.

Results

On days 1 and 10, PTFE exhibited the highest absorbance value with significant differences compared to the other groups. On day 30, TRP and PTFE showed significantly higher absorbance values than GP, VPS, and OR, but no significant difference was detected between TRP and PTFE (p = 0.424). The absorbance values of TRP and PTFE from days 1, 10, and 30 showed significant intragroup differences, while those of the other groups did not. In terms of the removal convenience on days 1, 10, and 30, VPS achieved the best performance, followed by PTFE, OR, TRP, and GP.

Conclusion

Within the limitations of this experiment, VPS and OR showed better sealing efficacy against microleakage and a more convenient removal than the other materials; thus, VPS and OR are recommended for clinical use.

Mechanical, Chemical, and Biological Properties of 3D-Printed Abutments: A Systematic Review

Aim:

A systematic review of the methods of 3D printing and the materials used so far for the manufacture of abutments was performed to evaluate whether their clinical use is indicated through the mechanical, chemical, and biological analyses carried out.

Materials and Methods:

An electronic search conducted by three independent reviewers was carried out in the PubMed, Web of Science, Cochrane Library, Science Direct, and Lilac databases. The inclusion criterion was researching articles in English that contained as subject the manufacturing of abutments through 3D printing/additive manufacturing. Any meta-analyses, reviews, book chapters, abstracts, letters, conferences papers, and studies without abutments printed were excluded.

Results:

We found 780 references, which after applying the exclusion criteria resulted in the final inclusion of seven articles for review. The studies had a high heterogeneity, showing different materials and methodologies to manufacture abutments, which makes a comparison between them difficult, and for this reason it was not possible to carry out a meta-analysis with the data found.

Conclusions:

Even with the limitations found in the present research, it is possible to conclude that printed abutments have adequate mechanical, chemical, and biological properties that can indicate their clinical use. 3D printing presents high accuracy and speed and can produce customized abutments according to each case.

Sealing Efficacy of the Original and Third-Party Custom-Made Abutments-Microbiological In Vitro Pilot Study

Implant–abutment connection (IAC) is a key factor for the long-term success and stability of implant-supported prosthodontic restoration and its surrounding tissues. Misfit between prosthodontic abutment and implant at the IAC leads to technical and biological complications. Two kinds of prosthodontic abutments are currently available on the market: original and third-party abutments. The aim of this pilot study was to test and compare the internal fit (gap) at the implant–abutment interface depending on the abutment fabrication method based on microbial leakage in static conditions and the need for the use of gap sealing material. Two groups of 40 implants were formed on the basis of the type of abutment. In each of the groups of two implant systems, two subgroups of 10 implants were formed. The tested subgroups consisted of 10 implants with sealing material and a negative control subgroups consisting of 10 implants without any sealing material. The test material, GapSeal (Hager and Werken, Duisburg, Germany) was applied in the test subgroups. The implant–abutment assemblies were contaminated with a solution containing Staphylococcus aureus and Candida albicans for 14 days under aerobic conditions. Results showed that there was no statistically significant difference regarding the microbial leakage between the original and third-party custom-made abutments, regardless of the use of sealing material. It can be concluded that the abutment fabrication method has no significant influence on sealing efficacy regarding the bacterial and fungal leakage in static conditions.

Performance of different abutment/implant joints as a result of a sealing agent

Purpose This in vitro study aimed to evaluate the effectiveness of a sealing agent in sealing the abutment/implant interface and the preload maintenance of retaining screws after mechanical cycling.Methods Six groups (n = 12) were evaluated according to the abutment/implant system (external-hexagon implant and UCLA abutments, EHU; Morse taper implant and UCLA abutments, MTU; and Morse taper implant and flexcone abutments, MTF) and the presence of an anaerobic gel sealing agent (control group, no sealing agent; experimental group, sealing agent). Toluidine blue (0.7 μL) was inserted into each implant and the abutments were attached to the implants using a digital torque wrench to evaluate the sealing of the abutment/implant interface. The specimens were tested through mechanical cycling (1 × 10⁶ cycles, 2 Hz, and 130 N). Dye release from the abutment/implant interface was analyzed using a spectrophotometer, and the reverse torque values were obtained using a digital wrench. Reverse torque and dye release data were measured after mechanical cycling and analyzed using ANOVA and Tukey's test (α =.05).Results All experimental groups showed higher reverse torque values than the control groups (P <.05). In general, the MTU and MTF experimental groups, as well as the MTF control group, showed no significant dye release at different periods (P >.05).Conclusions The use of a sealing agent improved the preload maintenance of screw-retained implant-supported prostheses. The sealing agent was effective in sealing the Morse taper connection.

Comparison of the Morse Cone Connection with the Internal Hexagon and External Hexagon Connections Based on Microleakage - Review

The gap formed at the abutment-implant interface brings about a bacterial colonization. In addition, a bacterial reservoir can be established within the implant. The build-up of microorganisms around the implant can cause soft tissue infections and bone loss around the implant, which can lead to implant failure. Our literature review aimed to evaluate the infiltration at the implant-abutment interface, comparing the Morse cone connection with the external hexagon and internal hexagon connections. A literature search using the PubMed database was performed on March 24, 2021. The search terms were combinations of "Morse cone" or "Morse taper" with each of the following terms (individually): "microleakage", "leakage", "infiltration", and "penetration". The inclusion criterion was in vitro studies comparing the Morse cone with the external hexagon and/or internal hexagon, based on infiltration at the implant-abutment interface. The exclusion criterion was the evaluation of microleakage at the implant-abutment interface after applying a sealant over this region. The search was expanded as needed. There was no limit on the year of publication, and only articles written in English were included. In addition, references cited in included articles were also included in this review when they were appropriate. This literature review concluded that, in most cases, the microleakage in the Morse cone connection was lower when compared with the external hexagon and internal hexagon connections.