Effect of CAD/CAM Abutment Height and Cement Type on the Retention of Zirconia Crowns

Ti-Base abutment height and cement type on the retentiveness of zirconiabased restorations

Purpose: To evaluate Ti-Base abutment height and cement type on the retentiveness of zirconiabased restorations.

Material and methods: Four millimeter (tall) and 2.5-mm-height (short) abutments along with temporary (provisional), glass ionomer (Meron), self-adhesive (U200), and conventional resin cement (Ultimate) were evaluated using pull-out testing (n ¼ 10 crowns/group).

Results: Tall and short abutments demonstrated similar retention for all within cement comparisons, except U200 (P ¼ 0.032). Resin cements exhibited superior retentiveness than others (P , 0.01). Although no significant difference was evidenced between resin cements for short abutments, Ultimate evidenced higher retention than U200 for tall abutments (P ¼ 0.043).

Conclusions: Although Ti-Base abutment height has not influenced zirconia superstructures’ retentiveness, resin-based cements significantly evidenced higher retention than glass ionomer and temporary cements. (Implant Dent 2018;27:1–6)

Key Words: abutment design, dental cements, zirconia, dental implants, pull-out test

Implant dentistry is a well-established treatment option that has been demonstrating high success rates in longterm follow-up studies.1,2 When implant surgical protocols are strictly followed, metallic device osseointegration is expected to be uneventful. Despite the high success rates, biological and technical complications are frequently described for implant-supported reconstructions. Although still debated, it seems that the rate of such complications in internally connected implants are lower compared with external connections. In a systematic review that analyzed more than 1000 patients, only 61.3% of them were free of any complication after 5 years of function. Abutmentor occlusal screw loosening was the most common technical complication (12.7%), followed by crown loss of retention (5.5%), veneer fracture (4.5%), and screw and abutment fracture (0.35%). Consequently, current research in implantology has focused on the improvement of prostheses’ longevity and retrievability.

Most implant rehabilitations comprise one- or 2-piece restorations where a crown can be cemented or screwed on the abutment. Substantial literature findings are categorical concerning the advantages and disadvantages of both prosthesis retention systems. Although screw-retained restorations are known for their retrievability, cementretained advantages include enhanced esthetic, easy handling, reduced laboratory technique sensitivity, ability to correct minor casting misfits between the superstructure and abutment, prevention of microorganism colonization of the inner part of the implant, and possibility of implant alignment correction. Nonetheless, loss of retention is the weakness of such system along with periodontal concerns relative to remnants of cement in the gingival sulcus.

Camila E. P. Silva, DDS, Simone Soares, DDS, MS, PhD, Camila M. Machado, DDS, MS, Edmara T. P. Bergamo, DDS, MS, Paulo G. Coelho, DDS, MS, PhD, Lukasz Witek, MS, PhD, Ilana S. Ramalho, DDS, MS, Ernesto B. B. Jalkh, DDS, MS, and Estevam A. Bonfante, DDS, MS, PhD