Dental Implant Abutments and Their Selection - A Review

Dental implants have become the most promising and accepted prosthetic alternative to missing teeth. Innovative and technological advances in implant dentistry have improved the performance and long term prognosis of dental implants. The growing demand for dental implants has led many manufacturers to enter the industry. With this growth in implant dentistry various implant brands and their components are made available in the markets that vary in terms of design and other features. Success of implant restorations is related to various components involved with the prosthesis. Implant abutment is the link between implant and restoration; right selection of this abutment is vital for the success of implant prosthesis. There are varieties of implant abutments available in the market. Clinician should have adequate knowledge about these abutments and various factors that affect abutment selection, to choose the right one. Each implant case is different and clinician should be able to identify requirements of every individual case and choose the best suitable abutment available in the market. These abutments vary in implant abutment connection, material, type of retention, and fabrication methods. Though the ideal concept is prosthetically driven implant placement, many times anatomical features, esthetic requirements, soft tissue profile, axial load distribution, malpositioned implants, and many other patient factors do not allow ideal implant placement. Such cases can be managed by careful selection of abutments by assessing the clinical requirements, thus offering better treatment outcome. This paper is an attempt to contemplate various factors affecting abutment selection, and throw light on various implant abutments available in the market, thus guiding the clinician in abutment selection. Hence this article summarizes complete information about the implant abutments, including introduction, types, selection, and different abutments available in market. KEY WORDS Abutment Material, Implant Abutments, Implant Abutment Connection, Prosthesis Retention

Vertical Discrepancy in Height of Morse Cone Abutments Submitted to Different Torque Forces

The present study aimed to evaluate the influence of manual torque (10 Ncm) versus clinical torque (30 Ncm), which is recommended by the manufacturer, on the total length of morse cone implant abutments. Twenty specimens were prepared and distributed into two groups: group 1 with ten analogs for morse cone type implant, and group 2 with ten morse type implants, size 4.3 × 15 cm. In each group, the distance between the implant platform to the top of the prosthetic abutment (abutment height) was measured and subjected to a torque of 10 Ncm. Then, the 30 Ncm torque was applied to the same abutment, and abutment height was measured. The distance between the top of the abutment and the implant/analog base was measured. In order to verify the clinical reproducibility of the experiment, comparisons between the abutment height of the analog at 10 Ncm and the implant at 30 Ncm were performed, showing a greater discrepancy in torque for the 10 Ncm analog (p < 0.05). In order to verify if the change in the laboratory protocol from 10 to 30 Ncm could minimize the differences in the height of the prosthetic abutments, the abutment height in groups 1 and 2 was compared with 30 Ncm, and no significant difference was observed (p > 0.05). The data indicated that the manual torque and the torque recommended by the manufacturer influence the total length of the prosthetic abutments of morse cone implants.

Zirconia Materials for Dental Implants: A Literature Review

Titanium is currently the most commonly used material for manufacturing dental implants. However, its potential toxic effects and the gray color have resulted in increasing requests for metal-free treatment options. Zirconia is a type of ceramic materials that has been extensively used in medicine field, such as implant abutments and various joint replacement appliances. Amounts of clinical evaluations have indicated good biocompatibility for zirconia products. Besides, its toothlike color, low affinity for plaque and outstanding mechanical and chemical properties have made it an ideal candidate for dental implants. The aim of this study is to review the laboratory and clinical papers about several kinds of zirconia materials and zirconia surface modification techniques. Although there are plenty of literatures on these topics, most of the researches focused on the mechanical properties of the materials or based on cell and animal experiments. Randomized clinical trials on zirconia materials are still urgently needed to validate their application as dental implants.

Retention of different temporary cements tested on zirconia crowns and titanium abutments in vitro

Purpose The aim of the present study was to examine the retention force of monolithic zirconia copings cemented with various temporary cements on implant abutments in vitro. Methods Sixty exercise implants with pre-screwed implant abutments were embedded in resin. Subsequently, 60 CAD/CAM manufactured zirconia copings were divided into three main groups [Harvard Implant Semi-permanent (HAV), implantlink semi Forte (IMP), Temp Bond NE (TBNE)]. The zirconia copings were cemented on the implant abutments and loaded with 35 N. Specimens were stored in distilled water (37 °C) for 24 h. Half of the test specimens of each group were subjected to a thermocycling (TC) process. Retention force was measured in a universal testing machine. Using magnifying glasses, the fracture mode was determined. Statistical analysis was performed applying the Kruskal-Wallis test, the post hoc test according to Dunn-Bonferroni and a chi-square test of independence. Results Without TC, IMP showed the highest retention of the three temporary luting agents (100.5 ± 39.14 N). The measured retention forces of IMP were higher than those of HAV (45.78 ± 15.66 N) and TBNE (61.16 ± 20.19 N). After TC, retention was reduced. IMP showed the greatest retentive strength (21.69 ± 13.61 N, three fail outs). HAV and TBNE showed pull-off forces of similar magnitude (17.38 ± 12.77 N and 16.97 ± 12.36 N, two fail outs). The fracture mode analysis showed different results regarding the tested cements before and after TC (facture type before/after TC): IMP (III+II/III), HAV (I/II) and TBNE (III/III). There were clear differences of the fracture modes regarding the examination before and after TC. Conclusions Within the limits of this study, IMP showed the highest pull-off forces under the chosen test conditions. All three temporary luting agents showed lower retention forces after TC. Retention values in the individual cement classes were very heterogeneous. Easy cement removal in the crown lumen favours the dominance of adhesive cement fractures on the abutment and adhesive/cohesive cement fractures on the abutment with HAV appears advantageous in case of recementation of the superstructure.

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.

Factors Influencing Marginal Bone Loss around Dental Implants: A Narrative Review

Implant supported dental prostheses are increasingly used in dental practice. The aim of this narrative review is to present the influence of transmucosal surface of prosthetic abutment and implant on peri-implant tissue. The article describes causes of bone loss around the dental implant. Moreover, properties of different materials are compared and discussed. The advantages, disadvantages, and biomechanical concept of different implant-abutment connections are presented. The location of connections in relation to the bone level and the influence of microgap between the abutment and implant are described. Additionally, the implant abutments for cemented and screwed prosthetic restorations are compared. The influence of implant and abutment surface at the transmucosal level on peri-implant soft tissue is discussed. Finally, the biological aspect of abutment-implant connection is analyzed.

Patient Satisfaction and Pink Esthetics of PEEK Versus Zirconium Abutments in the Esthetic Zone (A Randomized Controlled Trial)

Objective: This study was performed to evaluate the use of PEEK abutments versus zirconium abutments with lithium disilicate superstructure on the esthetic acceptance and peri-implant clinical parameters. Zirconium abutments were found to have high surface roughness even after polishing. This causes a remarkable collapse of the soft tissue papilla that is a primary factor in the Pink Esthetic Score(PES), resulting in failed esthetic restoration in the anterior esthetic zone. Material and Methods: Twenty patients who needed a single implant restoration in the esthetic zone were included in this study. Eighteen patients completed screening, baseline, three-month, six-month, and twelve-month follow-up visits. At the screening visit, the patients were randomly allocated into two groups: Zirconia abutments (A) Group, and PEEK abutments (B) Group, both of which were restored with IPS e.max CAD superstructure. Patients Satisfaction was assessed by visual analogue scale (VAS). Pink esthetics score (PES), modified plaque index (mPI) and modified gingval index (mGI) were also assessed. Results: All implants were successfully osseo-integrated with a 100% survival rate over one year. Patient satisfaction was significantly higher for the PEEK group than the zirconium group. The pink esthetic score showed no statistical significance between both groups. The modified plaque index was significantly lower for the PEEK group than the zirconium group. The modified gingival index showed no statistical difference between both groups. Conclusion: PEEK revealed to be a versatile material to replace zirconium for implant abutments, due to its lower plaque affinity and higher patient satisfaction. Keywords Dental implantation; Patient satisfaction; PEEK abutments; Pink esthetic score (PES); Zirconium abutments.

Effect of Abutment Geometry and Luting Agents on the Vertical Marginal Discrepancy of Cast Copings on Implant Abutments: An In Vitro Study

Aim. Vertical marginal discrepancy (VMD) influences the success of implant-supported restorations. However, there is little literature that has investigated the influence of geometry and cementing agent on changes in VMD of metal copings on implant abutments. The objective was to evaluate the effect of the geometry of the abutment and cementing agents on VMD. Methods. Cast copings were cemented on implant abutments customized cylindrical (4, 5.5, and 7 mm) and on hexagonal implant abutments (4 mm) cemented or uncemented molded copings were placed (n = 4, totally 64 samples) with different luting agents. The VMD of the copings were measured in the coping-abutment interface at three reference points using a stereomicroscope. The independent Student’s t test was used for comparison between the two different abutment walls. The post hoc statistical analysis was performed by the Tukey test. Results. There was a significant VMD increase between noncemented and cemented cast copings using different luting agents. Abutment geometry and luting agents significantly influenced the VMD p ≤ 0.05 . Cylindrical abutment at 7 mm in height cemented with different luting agent tested showed significantly higher VMD values than cylindrical abutments of 4 mm p = 0.019 . Hexagonal abutments with a 4 mm height showed significantly higher VMD values than cylindrical 4 mm abutments using zinc oxide noneugenol and glass ionomer cements p = 0.032 . Conclusions. Abutment geometry and luting agents influence the VMD of cast copings cemented on implant abutment. The higher the cylindrical abutment, the greater the VMD, and hexagonal wall abutments promote greater marginal gap.