Abstract
Statement of problem
Screw loosening is the most common mechanical complication with implant prostheses.
How the alteration of implant-to-abutment connection surfaces that occurs during laboratory
procedures affects screw loosening is unclear.
Purpose
The purpose of this in vitro study was to compare the reverse tightening value (RTV)
differences between custom castable abutments before casting, after casting in a conventional
manner, and after casting with custom protector caps and pegs.
Material and methods
Thirty implants with a standard-diameter conical connection (NobelReplace Conical
Connection 4.3×13 mm; Nobel Biocare AG) and 30 premachined 4.3-mm GoldAdapt abutments
(GoldAdapt; Nobel Biocare AG) were selected for this study. Specimens were divided
into 3 groups (n=10): the uncast custom castable abutment group (UCCA) in which abutments
were new and not cast; the unprotected custom castable abutment group (UPCCA) in which
abutments were cast and devested with airborne-particle abrasion; and the protected
custom castable abutment group (PCCA) in which abutments were cast by using protector
caps and pegs made by milling zirconia and then devested with airborne-particle abrasion.
All abutments in each group were tightened to 35 Ncm with a calibrated digital tightening
device. After 10 minutes, all screws were retightened to 35 Ncm. At 3 hours, each
screw was loosened, and the value at which the initial loosening occurred was documented
as the RTV. The results were statistically analyzed with 1-way ANOVA to explore differences,
and post hoc tests with Tukey adjustment were used for multiple comparisons.
Results
Among the tested groups, the mean RTV ranged from 19.89 Ncm to 27.19 Ncm: UCCA 27.19
Ncm, UPCCA 19.89 Ncm, and PCCA 24.24 Ncm. A significant difference was found among
the tested groups (P<.05).
Conclusions
Casting procedures, especially devestment with airborne-particle abrasion, affected
implant-abutment connections and the seat site of the screw. Protecting the implant
connection site and the seat site of the abutment screw with protector caps and pegs
prevented a significant loss of the RTV.
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Journal of Prosthetic DentistryAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Branemark system implants in the posterior maxilla: clinical study of 660 implants followed for 5 to 12 years.Int J Oral Maxillofac Implants. 2000; 15: 646-653
- The fit of cast and premachined implant abutments.J Prosthet Dent. 1998; 80: 184-192
- Examination of the implant-abutment interface after fatigue testing.J Prosthet Dent. 2001; 85: 268-275
- Marginal discrepancy of components utilized for implant framework construction.Loma Linda University Electronic Theses, Dissertations & Projects, 1999: 352 (Available at:)https://scholarsrepository.llu.edu/etd/352/Date accessed: March , 1999
- Effects of fabrication, finishing, and polishing procedures on preload in prostheses using conventional “gold” and plastic cylinders.Int J Oral Maxillofac Implants. 1996; 11: 589-598
- Abutment selection for anterior single tooth replacement. A clinical report.J Prosthet Dent. 1993; 69: 133-135
- Single-tooth implant rehabilitation: a retrospective study of 67 implants.Int J Prosthodont. 1994; 7: 525-531
- An introduction to the design and behavior of bolted joints.Marcel Dekker, Inc, New York1981: 109-136
- Prosthetic complications with implant prostheses (2001-2017).Eur J Oral Implantol. 2018; 11 Suppl 1: S27-S36
- Abutment screw loosening in single-implant restorations: a systematic review.Int J Oral Maxillofac Implants. 2008; 23: 681-690
- Influence of implant abutment fabrication method on clinical outcomes: a systematic review.Eur J Oral Implantol. 2017; 10 Suppl 1: 67-77
- The glossary of prosthodontic terms. Ninth edition.J Prosthet Dent. 2017; 117: e1-e105
- The “UCLA” abutment.Int J Oral Maxillofac Implants. 1988; 3: 183-189
- The UCLA abutment: a four-year review.J Prosthet Dent. 1992; 67: 509-515
- Implant/abutment biomechanics and material selection for predictable results.Compend Contin Educ Dent. 2018; 39: 440-444
- Protecting critical connection sites of a custom cast abutment with a protector cap during fabrication.J Prosthet Dent. 2020; 124: 144-147
- Shear bond strength of porcelain to a new millable alloy and a conventional castable alloy.J Prosthet Dent. 2015; 113: 329-335
- An introduction to the implant crown with an esthetic adhesive margin (ICEAM).J Esthet Restor Dent. 2012; 24: 246-254
- Airborne-particle abrasion; searching the right parameter.J Dent Sci. 2018; 13: 293-300
- Surface analysis of porcelain fused to metal systems.Dent Mater. 2006; 22: 330-337
- Accuracy of ringless casting and accelerated wax-elimination technique: a comparative in vitro study.J Prosthodont. 2014; 23: 157-162
- Comparison of screw loosening, rotation, and deflection among three implant designs.J Prosthet Dent. 1995; 74: 270-278
- Standard handbook of machine design.lst ed. McGrawHill, New York1986: 23-26
- The effect of implant diameter, restoration design, and occlusal table variations on screw loosening of posterior single-tooth implant restorations.J Oral Implantol. 2001; 27: 63-72
- Torque required to loosen single-tooth implant abutment screws before and after simulated function.Int J Prosthodont. 1993; 6: 435-439
- The relationship between implant preload and screw loosening on implant-supported prostheses.J Oral Implantol. 2002; 28: 67-73
- Influence of reverse torque values in abutments with or without internal hexagon indexes.J Prosthet Dent. 2014; 112: 824-827
- In vitro assessment of three types of zirconia implant abutments under static load.J Prosthet Dent. 2013; 109: 255-263
- Young's modulus of trabecular and cortical bone material: ultrasonic and microtensile measurements.J Biomech. 1993; 26: 111-119
- Effect of casting procedures on screw loosening in UCLA-type abutments.J Prosthodont. 2006; 15: 77-81
- Screw loosening of different UCLA-type abutments after mechanical cycling.Braz J Oral Sci. 2013; 12: 228-232
- The external hexagonal interface and screwjoint stability: a primer on threaded fasteners in implant dentistry.Quintessence Dent Technol. 2000; 23: 91-105
- Elongation and preload stress in dental implant abutment screws.Int J Oral Maxillofac Implants. 1995; 10: 529-536
- Comparison of screw retention of nine abutment systems: a pilot study.Implant Dent. 1997; 6: 2831
- The effect of implant/abutment hexagonal misfit on screw joint stability.Int J Prosthodont. 1996; 9: 149-160
Article info
Publication history
Published online: November 17, 2022
Publication stage
In Press Corrected ProofIdentification
Copyright
© 2022 by the Editorial Council for The Journal of Prosthetic Dentistry.