Are implants for life? Reconstruction longevity and stability
Although implant losses have been recorded for as long as implant therapy has been used, complications have been under-reported in the literature. For this reason, the 5-year figures of systematic reviews on biological and technical complications have remained below 10% (Berglundh et al. 2002; Goodacre et al. 2003).
“Complications have been under-reported in the literature”
Regarding partial reconstructions on implants, there have been many attempts to determine the potential influence of different designs on treatment outcomes, yet there is insufficient scientific evidence to support definitive guidelines about prosthesis design (Weber & Sukotjo. 2007).
A systematic review focusing on single implant-supported crowns reported failure rates of 5% and 9% for porcelain fused to metal (PFM) and all-ceramic crowns respectively after 5 years (Jung et al. 2008). This paper also noted the relatively high rate of complications: around 9.7% for biological complications and almost double that figure for technical complications.
Treatment outcome assessments for implant therapy should include criteria at four levels: implant, peri-implant soft tissues, prosthesis and patient satisfaction (Papaspyridakos et al. 2012). Success should ideally evaluate the implant-prosthetic complex as a whole, meaning that all complications should be discounted/disqualified from success rates. The speaker stated that success should mean no complications, including technical ones.
“Success should mean no complications, including technical ones”
A clinical study of single implant-supported crowns reported a 10-year prosthesis survival rate of 97.7%. It should be noted, however, that the success rate dropped to 70.8% because of the total rate of mechanical-technical complications (24.7%), especially ceramic chipping (Wittneben et al. 2014).
The speaker highlighted differences between publications over the last two decades concerning survival and complication rates (Pjetursson et al. 2014). Overall, 5-year survival rates from more recent studies were improved across all prosthesis types, but complication rates were also higher (rising from 14.8% to 27.1%), with fracture of veneering materials being especially common.
Regarding practical recommendations, no differences in outcomes have been observed, regardless of the type of retention used. However the choice between screws or cement depends on technical feasibility and operator preference (Wittneben et al. 2017). The speaker said he prefers to use cement on tissue-level implants with a shallow sulcus, especially in posterior areas. In cases where implants are deeper, screw-retention is generally the safer option.
Regarding material selection for abutments, a recent systematic review found no differences between titanium and ceramic abutments after five years (Zembic et al. 2014). However, it would be prudent to use metal as the standard, and only choose ceramic in cases where it can provide a real aesthetic advantage (i.e. in cases involving thin tissues which would be prone to metal transparency).
“Data from long-term studies is still required for monolithic
implant-supported restorations in zirconia or lithium disilicate”
Preliminary data indicates high short-term survival rates for monolithic implant-supported restorations in zirconia or lithium disilicate. However, data from long-term studies is still required to validate the wide use of this protocol.