Nothing lasts forever, and there are very few things which last for life. Teeth should last most people a lifetime, but this is not always the case. Implants were supposed to last decades, but complications can often reduce their intended life-span and cannot always be successfully resolved.

Patients’ expectations about the longevity of implant restorations can be unrealistic, based on the complexity and cost of the therapy required. Careful planning, treatment and maintenance are required to prevent complications arising.

“Patients’ expectations about the longevity of implant restorations can be unrealistic”

The chairs described a clinical situation in which the patient had severe periodontitis and had received implants, and peri-implantitis had subsequently occurred. This situation invites a number of questions and challenges regarding the outcomes of the treatment and the restoration, and regarding the maintenance of the affected teeth and implants (Figures 1–5). The chairs invited the speakers to consider these questions.

They asked: if the patient were to receive adequate treatment, how long could their oral health be maintained? How long can the teeth be maintained – 5, 10 or 20 years? Are implants indicated in patients with periodontitis, and is this patient a suitable candidate for implant placement? And to what extent can periodontal breakdown be prevented?

How long could the treated peri-implantitis be kept under control? Is there a treatment protocol available which is better than others? What type of prosthesis would be the best option for this patient? Do implant surfaces and designs influence implant longevity? For how long could implants be maintained? And which approach would be easier to maintain in the long term: compromised teeth or implants?

“How long could the treated peri-implantitis be kept under control?”

If the patient had a fixed restoration in the lower arch on teeth, which prosthesis would a prosthodontist prefer to maintain: an implant-supported or tooth-supported fixed prosthesis? Is it the materials we choose or the design of the prosthesis which are most critical for longevity? In terms of a full-arch rehabilitation, does the length of cantilever have an impact on the longevity? With all the chipping we have seen in this patient, is it better to have a segmented reconstruction or a full-arch reconstruction?

Presentation figures

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

The speaker outlined four questions which would be addressed in his presentation:

1. What are the rates of tooth survival in the general population and in people with periodontitis?
2. How can periodontal treatment change the trajectory of a patient’s prognosis?
3. What can be done for tooth preservation?
4. What are the key differences with implants in terms of prevention?

A recent systematic review of the rate of tooth loss in the general population found that 0.1–0.3 teeth are lost per patient per year (with some variation between continents) (Needleman et al. 2018). From this figure, it is remarkable that only a minority of people lose teeth.

“Only a minority of people lose teeth: 0.1–0.3 teeth are lost per patient per year”

Another systematic review reported on tooth loss in patients who had received periodontal treatment and proper maintenance (Chambrone et al. 2010). The results showed a mean tooth loss of 0.05–0.1 per patient per year, most of which occurred in a small fraction of patients and was caused mostly by reasons other than periodontitis.

From this evidence, we can see that well-maintained periodontal patients are four times less likely to lose teeth than the general population. Periodontal therapy is very powerful and effective.

“Well-maintained periodontal patients are four times less likely to lose teeth than the general population.”

The speaker went on to discuss what can be done for long-term preservation of teeth in cases involving extremely compromised conditions and treated with regenerating intrabony defects (Cortellini & Tonetti. 2004). Tooth survival was 96% at 10 years.

The 20-year results of an RCT comparing periodontal regeneration in compromised teeth with access flap surgery were recently published (Cortellini et al. 2017). They showed better tooth retention and cost-effectiveness for the regenerative approach.

The speaker also discussed the 5 and 10-tear follow-up of a study comparing periodontal regeneration at teeth compromised by periodontal defects beyond the apex with their extraction and replacement with implants or bridges (Cortellini et al. 2011). The regenerated group showed tooth retention of 88% at 10 years (all these teeth should have been extracted according to current standard practice because of the deep lesions). Furthermore, the cost for treatment and management of 10-year complications was much lower for the cases in which teeth were retained.

“Periodontal regeneration has been proven to be effective even in compromised cases”

The aim of periodontal treatment is generally to make the case maintainable in the long-term. This involves controlling the risk profile and keeping pocket depth shallow in order to control inflammation. It is an attainable goal.

Is the previous data gathered from teeth also applicable to implants?

A clinical study showed that the inflammatory response to experimental plaque accumulation at teeth and implants was reversible (Salvi et al. 2012). A recently performed study (Chan et al. 2019), however, shows that plaque-induced inflammation at implants is only reversible if the implant is not placed too deeply into the soft tissues (which is something clinicians frequently do to mask the metal components in the soft tissue mucosal tunnel). A retrospective clinical study on patients with peri-implant mucositis reported that only a third of the cohort returned to normal after following a hygiene programme (Costa et al. 2012).

“It seems that it is harder to resolve inflammation in implants than in teeth, due to the deeper peri-implant sulci”

This less favourable peri-implant soft tissue response may have been due to the fact that implants with a deeper sulcus than natural teeth may not allow proper plaque control.

Unfortunately, implants are not for life. There is a high percentage of patients who experience implant loss and/or peri-implant infections. A systematic review published in 2012 found that 7.1% of implants were lost ten years after placement (Pjetursson et al. 2012). The speaker stated that a long-term clinical study by him and his group found that 4.3% of implants were lost, and implant loss seemed to be clustered in individuals (implant loss affected 10.3% of the patients). The overall survival rate after ten years was 95.7% (Roos-Jansåker et al. 2006).

“Unfortunately, implants are not for life.”

For the implants which do survive, a (highly varied) number have been reported to experience peri-implantitis (PI). A number of different figures have been reported in the literature:

• Atieh et al. 2013: 19% of patients experienced PI (10% of implants)
• Derks & Tomasi. 2015: 1–47% prevalence of PI, with a weighted mean prevalence of 22%
• Renvert et al. 2017: 14% PI prevalence, mostly confined to a few individuals
• Muñoz et al. 2018: 17% PI prevalence (with high heterogeneity), found in their recent meta-analysis

These variations between reported rates of PI may be due to differences in the defining criteria applied to PI and/or limitations within the studies. Despite the varying numbers reported in the literature, however, we can assume that around 15–20% of patients will experience peri-implantitis (especially smokers and periodontitis patients). From these studies, it can be concluded that implant loss and peri-implantitis tend to cluster within individuals.

How successful can PI treatment be? It is often hard to control the progression of infection; however, maintenance care can sometimes hinder/prevent progression. Sometimes, removal of the affected implant is the best option. An RCT analysing a resective approach aiming to reduce pocket depth was recently performed. The study found that only 45% of treated implants fulfilled the success criteria, although the authors noted that implants with a turned surface had a 79% success rate, and implants with a modified surface had only 34% (Carcuac et al. 2015).

“Sometimes, removal of the affected implant is the best option”

The regenerative approach for treating PI was also studied in a recently published RCT. Patients with three- or four-wall intra-osseous defects were treated with flap surgery and decontamination, with or without augmentation with xenograft. The results of the study were highly significant and favoured the use of biomaterials (Renvert et al. 2018).

To increase the longevity of implants, the speaker outlined his recommendations:

• periodontitis must be treated before implants are placed
• a smoking cessation programme should be offered to patients who smoke
• individuals with poor metabolic control and/or cardiovascular disease should be considered as ‘risk patients’
• prostheses must be designed with suitable accessibility for oral hygiene
• screw-retained prostheses should be used to facilitate maintenance
• the frequency of maintenance therapy should be decided on an individual basis

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.

Could the harmful effect of deep mucosal tunnels around implants be due to the height of the soft tissue or have something to do with the quality of the fit or the bacteria that might be found at that micro-gap level?

Tonetti: From our study, we were unable to identify whether the reason for this is the hardware and/or the depth of the sulcus. The point is that whenever the mucosal tunnel is deeper (self-performed), professional hygiene seems to be insufficient to remove plaque and keep a healthy interface or reverse experimentally induced peri-implant mucositis. The inflammation therefore can become chronic, and its persistence seems to lead to the onset of peri-implantitis.

Orthopaedic surgeons often talk about ‘repositioning’ after several years and do not expect their prostheses to substitute the natural structures of the joints. However, in implant dentistry we talk about failure rates and extraction of diseased teeth (and replacement with implants) is considered a correct indication. Given this, should we adopt the views and terminology of orthopaedic surgeons, and change the general expectations associated with implant therapy?

Weber: In joint replacement, the best approach is to wait as long as possible. In a similar way we should maintain natural teeth for as long as we can.

Renvert: Infections around teeth are much easier to handle than peri-implantitis. So-called ‘hopeless teeth’ can be maintained for long periods of time; in contrast, trying to keep infected implants is harder. The success rate for treating peri-implantitis is roughly only about 40%. For this reason, the wisest attitude is to take measures to prevent peri-implant infections from the very beginning of treatment.

Tonetti: The biggest issue is that as the population ages and patients are getting older, and sometimes presenting with a very poor general condition, we have to play our cards (i.e. treating diseased teeth, replacing with implants etc.) in the best way we can. To keep our patients chewing, speaking and smiling, the critical question is when to play the cards, and how to modify the game as people get older and more ill.