S10 Implant Abutment Connections.pptx…….

………………,,,

1. IMPLANT ABUTMENT CONNECTION Presenter: Dr.Chaitra Guide: Dr.Vidya

2. INTRODUCTION Since the introduction of dental implants many changes were made in the implant systems to incorporate additional features or modifications to the existing systems. One among such modifications is design of the connection that allows the prosthetic super-structure to be attached to the implants.

3. The success of implant not only depends on osseointegration but also on the prosthetic elements. Particularly, the connection between implant and abutment is a key junction because it is the primary determinant of long term stability and strength of implants which in turn determines the final outcome of implant therapy.

4. Acc ording to Buser et al 2002 and Alberktsson et al 1986, dental implants can be considered successful if the peri implant crestal bone loss is <1.5mm in the first year and 0.2mm annually thereafter. Crest module   is that portion of implant fixture that provides connection to abutment and consists of a platform & anti rotation features.

5. IMPLANT ABUTMENT INTERFACE The implant-abutment interface is the surface where the dental implant and the prosthetic abutment connect. There is more than one type of implant-abutment interface and the one selected by the practitioner often depends upon the location of the implant and the type of prosthesis that will be attached.

6. CLASSIFICATION According to the geometrical configuration:

7. According to the space between the connecting parts:

8. According to the angulation of the connecting parts:

9. According to the extension of the geometrical figure above the body of the implant: Earlier the Branemark system was characterized by an external hexagon which was developed to facilitate implant insertion rather than to provide clinicians with an anti-rotational device. This external hexagon configuration has performed well over the years. But over a period of time the drawbacks of external connection came into light which led to the modification in implant abutment connection.

10. DRAWBACKS OF EXTERNAL HEX Not an effective anti-rotational device. Higher chance of rotational misfit. Abutment screw loosening reported in 6%-48% of the cases. Difficulty is approximation Inadequate microbial seal Less aesthetic To overcome these complications, various implant connections have evolved from it.

11. Due to increase of frequency of screw loosening in external hex design, various modification were introduced. To overcome the screw loosening caused by adverse force distribution and instability of the abutment connection the first change was done by increasing the width and height of the external hex connection. 

12. MODIFICATIONS TO EXTERNAL HEX Currently available external hex heights range from 0.7, 0.9, 1.0, and 1.2 mm and with flat–flat widths of 2.0, 2.4, 2.7, 3.0, 3.3, and 3.4 mm, depending on the implant platform. By increasing the width and height leads to increase in the fulcrum arm and the area of abutment screw engagement also increases, thus decreases the tipping forces on abutment screws and reducing the occurrence of screw loosening.

13. TAPERED HEXAGON CONNECTION I ntroduced to improve the fit between the implant and abutment by creating a 1.5-degree tapered interface. This design reduces rotational freedom and screw loosening by interlocking the mating hexes with a frictional fit, providing increased stability.   I ntroduced by Swede-Vent TL (Paragon Implant Co, Encino, CA), and also available in the Spectra implant system. C onfirmed zero micromotion at the implant-abutment interface.

14. EXTERNAL OCTAGONAL CONNECTION The external octagon design features an eight-sided implant-abutment interface that allows for 45° rotation of the abutment.  Due to its circular-like geometry, it provides minimal rotational resistance and is not considered very successful. I ncompatible with angled abutments. N arrow diameter implant (3.3 and 3.5 mm) by ITI Narrow Neck for mandibular anterior teeth I t claimed good lateral and rotational resistance and strength, though studies to support these claims are lacking.

15. SPLINE IMPLANT ABUTMENT CONNECTION Developed by Calcitek in 1992 This design features six spline teeth extending outward from the implant body that fit into six corresponding grooves in the abutment, creating a snug fit and providing excellent locational accuracy. Advantages: R educes screw loosening and minimizes rotational movement compared to traditional external hex designs, leading to increased stability between the implant and abutment.

16. INTERNAL HEX I ntroduced to reduce mechanical complications from external connections and decrease stress transfer to the crestal bone. Acting as anti-rotational and indexing features, these connections improve implant stability and simplify restorative procedures. Niznick in 1986 1.7mm deep hex below a 0.5mm wide 45 degree bevel.

17. ADVANTAGES Reduced vertical height which resulted in better esthetics Distribution of lateral loading deep within the implant Shielded abutment screw that caused less abutment screw loosening Internal wall engagement: less freedom of rotation. Wall engagement with the implant that buffers vibration, the potential for a microbial seal. Extensive flexibility.

18. PASSIVE FIT/ SLIP FIT 6-point internal hex: – Centre pulse-core vent/screw vent – Friadent-Frialit-2 12-point internal hex: – 3i-osseotite certain 3-point internal tripod: – Alatech technologies, Camlog – Nobel biocare /Replace select Internal octagon: Omniloc , Sulzer Calcitek

19. FRICTION FIT Locking taper/morse taper: - 8 degree taper (ITI straumann , Avana , 3i TG, Ankylos ) - 11 degree taper (Astra) -1.5 degree tapered rounded channel ( Bicon ).

20. SIX POINT INTERNAL HEXAGON The six-point internal hex is a widely used abutment fixture due to its hexagonal geometry, allowing the abutment to fit over the implant fixture at six different 60◦ angles. The six-point internal hex is a widely used abutment fixture due to its hexagonal geometry, allowing the abutment to fit over the implant fixture at six different 60◦ angles. The internal hexagon connection offers 60◦ indexing and rotational resistance, blending the benefits of cylindrical and internal connection designs.

21. TWELVE POINT HEXAGON The 12-point internal hexagon design allows the abutment to be positioned in 12 different orientations at 30◦ intervals, making it particularly useful for angled abutments. Research by Tang et al., demonstrated that this design provides better stress distribution and less displacement compared to other designs.

22. Studies using finite element analysis have shown that implant systems like the reduced-diameter 3i Implant System with a 12-point double internal hexagonal connection exhibit superior stress distribution and minimal displacement compared to other designs, such as those with external hexagonal connections like the Brånemark system.

23. THREE- POINT INTERNAL TRIPOD Design & Geometry: The three-point internal tripod design features a triangular internal geometry. System & Manufacturer: Introduced by Nobel Biocare as the Replace Select system. Available Sizes: Comes in diameters of 3.5, 4.3, 5, and 6 mm. Limitation: Restricted to 120-degree abutment positioning, making it less preferred clinically. Stress Distribution: Studies show that under off-axis loading, external hex connections distribute stress more favorably than the 12-point double hexagon design of the Replace Select system.

24. INTERNAL OCTAGONAL The internal octagonal implant features an 8-sided internal geometry allowing the implant to be positioned over the abutment at 45-degree intervals. Introduced by Omniloc , Sulzer Calcitek , this design presented thin walls and a small diameter resembling a circular profile, resulting in minimal rotational and lateral resistance during function.

25. MORSE TAPER The Morse taper implant-abutment connection design features a tapered projection from the abutment that fits into a corresponding tapered recess in the implant, creating a friction fit and cold welding at the interface. This design relies on the friction fit to prevent rotation and abutment screw loosening. The abutment and fixture act as a single piece due to the "cold -welding" effect, eliminating microgaps and preventing bacterial leakage. The taper interface also resists lateral loading, preventing the abutment from tilting

26. Sutter et al. proposed the Morse taper connection as an optimal combination of predictable vertical positioning and self-locking characteristics. Norton supported this by showing that conical connections between implant and abutment significantly enhanced the system’s resistance to bending forces. Levine et al. and Felton confirmed reduced complications, such as abutment screw loosening, with Morse taper connections compared to external hex connections.

27. DEGREE MORSE TAPER The ITI-Straumann implant design evolved into the Synocta design, which added an internal hexagon to the Morse taper connection, as proposed by Wiskott and Belser. This modification allowed for the rotation and repositioning of the abutment over the implant at different angles, facilitating precise transfer of the implant position to the master cast with only one transfer system and one analog .

28. DEGREE The fixture and abutment are securely connected at an 11.5-degree angle by the conical seal. Introduced by Bicon implants, this true Morse taper design features a 1.5◦ taper. Bicon claims that this taper provides a bacterial seal at the implant-abutment interface, with a microgap of less than 0.5 microns, preventing microbial leakage and reducing the risk of soft tissue inflammation and bone loss around the implant. The Bicon locking taper abutment, which has no screw, relies on friction to maintain its integrity.

29. BIOMECHANICAL FACTORS AFFECTING IMPLANT ABUTMENT INTERFACE Stress distribution:  Internal vs external hex comparisons According to Chun et al, it was found that the internal hex implant system generated the lowest Von Mises Stresses for all loading conditions because of reduction in the bending effect by sliding in the tapered joints between the implant and the abutment. Maeda et al, stated that almost the same force distribution pattern was found under vertical load in both systems. It was suggested that fixtures with internal-hex showed widely spread force distribution down to the fixture tip compared with external hex ones.

30. Balik et al investigated the strain distributions in 5 different implant-abutment connection systems under similar loading conditions. External hexagonal connection showed the highest strain values, and the internal hexagonal implant-abutment connection system showed the lowest strain values

31. Internal connection comparisons According to Saidin et al, the internal hexagonal and octagonal abutments produced similar patterns of micromotion and stress distribution due to their regular polygonal design. The internal conical abutment produced the highest magnitude of micromotion, whereas the trilobe connection showed the lowest magnitude of micromotion due to its polygonal profile.

32. Szyszkowski and Kozakiewicz concluded that t he internal cone implant-abutment connection causes less peri-implant bone resorption compared with the internal hexagon connection. MBL is lower in cases of internal cone joint in long-term follow-up. Both types of connections ensure a 100% implant survival rate after 5 years of observation.

33.  Conical vs Butt joint Stronger & More Stable – Conical abutments offer superior mechanical strength and long-term stability (Merz & Hunenbart ). Higher Strength – Conical joints are 60% stronger than external hex (Norton et al). Better Stress Distribution – Conical interfaces reduce shear stress and withstand higher axial loads (Hansson). Prevents Screw Loosening – Friction lock minimizes screw rotation (Sutter et al). Less Screw Loss – External hex connections are more prone to screw loss (Levine et al).

34. 2. Fatigue resistance: Fatigue is a progressive, localized and permanent structural damage that occurs in a material subjected to repeated or fluctuating strains. The design of the implant-to-abutment mating surface and the retentive properties of the screw joints affect the mechanical resistance of the implant-abutment complex.

35. Stronger Connections – Long internal tube-in-tube connections with cam-slot fixation enhance durability and fracture resistance ( Steinebrunner ). Comparison of Interfaces – External hexagon showed better fatigue resistance than cone-in-cone and internal hexagon, with no significant difference between the latter two ( Rebeiro et al). System Performance – The ITI system exhibited superior fatigue strength compared to the Brånemark system ( Khraisat et al).

36. Crestal bone loss: The literature indicates that type of implant abutment connection influences the stresses and strains induced in peri implant crestal bone. Crestal bone loss did not differ significantly. Slightly greater—60% for external hex and 52% for both internal octagon and internal Morse taper—during the healing phase (before occlusal loading) than during loading phases 1 and 2 (3 and 6 months after occlusal loading, respectively).

37. Microleakage: Microleakage – External connections showed more microleakage (1.22 µm) than internal connections (0.97 µm) (F. Gil et al). Bacterial Leakage – All tested implant systems ( Brånemark , Frialit-2, Camlog , Replace Select, Screw Vent) exhibited bacterial leakage ( Steinebrunner ). Endotoxin Tightness – Astra implants had better tightness against endotoxins than Ankylos implants (S. Harder et al). Bacterial Counts – Morse cone–connection implants had the lowest bacterial counts, with no significant difference between internal and external connections (Nascimento et al).

38. Platform switching: Definition – Involves using a smaller diameter abutment on a larger diameter implant collar, shifting the implant-abutment junction (IAJ) inward. Bone Preservation – Lazzara & Porter found that platform switching reduces peri-implant crestal bone loss by moving the inflammatory zone away from the bone.

39. Microgap Positioning – Placing the abutment-implant microgap closer to the implant’s central axis helps in minimizing bone resorption. Clinical Support – Studies confirm the benefits of platform switching in maintaining peri-implant bone stability.

40. Abutment type: Earlier the abutments were made of titanium until the recent introduction of ceramic abutments. The problems with titanium abutments are the micro gap, consecutive fatigue and wear at the interface. Yuzugullu et al found no significant difference in the microgap among titanium, alumina, and zirconia abutments after dynamic loading. Yuong Jo et al recommended using high-strength, low-friction abutment materials like Ti-6Al-4V for better implant-abutment stability.

41. CONCLUSION The implant-abutment interface plays a crucial role in lateral and rotational stability, affecting the overall prosthetic stability of implant-supported restorations. Internal connections offer better prosthesis retention, reducing stress on the implant's cervical region and retention screws. Conical interfaces, combined with retention elements at the implant neck, minimize micromotion. While all prosthetic platforms can achieve high success rates, careful case selection and adherence to their indications are essential. Reverse planning is strongly recommended to prevent implant overload and ensure long-term success.

42. REFERENCES Valvi NN, Khalikar S, Mahale K, Rajguru V, Mahajan S, Tandale U. Evolving interfaces: A comprehensive review of implant-abutment connections. IDJSR. 2024 Oct 28;12(3):123-9. Prithviraj D, muley N, gupta V. The evolution of external and internal implant–abutment connections: A review. Int dent res. 2012 apr 15;2(2):37. Ceruso f. Implant-abutment connections on single crowns: a systematic review. Orl . 2017;10(4):349. Implant abutment connections: a review. Annals of Clinical Prosthodontics June 2017-Volume 1- Issue 3 Page. No 13-25. Muley N, Prithviraj DR, Gupta V. Evolution of External and Internal Implant to Abutment Connection. Int J Oral Implantol Clin Res 2012;3(3):122-129. Szyszkowski A, Kozakiewicz M. Effect of Implant-Abutment Connection Type on Bone Around Dental Implants in Long-Term Observation. Implant Dentistry. 2019 Oct;28(5):430-6.