As a consequence of the increase in the popularity of dental implants, it is increasingly common to come across cases of peri-implantitis, a disease with a prevalence of 22%(1) in people with implants. For this reason, it is important to devote efforts to research into this subject matter. 

María Peñarrocha Diago. Tenured Professor of Oral Surgery. Master of Oral Surgery and Implant Dentistry, University of Valencia, Valencia. Amparo Aloy Prósper. Associate Professor of Oral Surgery. Master of Oral Surgery and Implant Dentistry, University of Valencia, Valencia. Hilario Pellicer Chóver. Associate Professor of the Master of Oral Surgery and Implant Dentistry, University of Valencia, Valencia. David Soto. Dentist. Student of the Master of Oral Surgery and Implant Dentistry, University of Valencia, Valencia. David Peñarrocha Oltra. Assistant Professor. Doctor of Oral Surgery. Master of Oral Surgery and Implant Dentistry, University of Valencia, Valencia. 

With the increase in the number of dental implants, some diseases such as peri-implant mucositis and peri-implantitis have increased their impact on the population. Both are inflammatory diseases that are triggered by an alteration in the balance between the bacterial load and the defence of the peri-implant tissues^(2,3). 

Bacterial colonisation plays an important role in the aetiopathogenesis of this disease, which is why treatment will aim to reduce or eliminate pathogenic microorganisms and provide patients with easier maintenance in the long term⁽⁴⁾. 

DETECTION 

There are several signs that indicate the appearance of peri-implant disease. The initial clinical presentation that is established is mucositis. Some of the most prominent symptoms are red gums, bleeding on probing and, in more advanced cases, the presence of pus⁽⁵⁾. 

Specifically, probing is the most useful tool that exists today to assess inflammation, which manifests with bleeding. Although it is not a perfect method, since it gives many false positives, it is the best tool available today. If bleeding does not occur, it can be said that the peri-implant tissues are stable^(6,7). 

When untreated, mucositis evolves into peri-implantitis, in which in addition to bleeding there is a loss of marginal bone. Periapical radiography is, thus, the method that should be used to determine the level of bone loss. In this case, detection is made by observing possible loss of bone mass in the crestal bone (figure 1). 

It is necessary to take into account that annual losses of under 1 mm may be caused by physiological remodelling and need not correspond to an infectious process. Periapical radiography is also useful to detect imbalances in the implant-prosthesis junction, in many cases a possible causal factor of peri-implantitis. 

RISK FACTORS 

Regarding prevalence, after 10 years, 80% of patients with implants suffer mucositis, and 20%, peri-implantitis. In addition, these cases seem to be most common among groups of people with certain habits or undergoing certain circumstances. 

For example, peri-implantitis has been observed to be more frequent in smokers or in people who have previously suffered from periodontitis or whose remaining teeth show periodontal disease. Implants should not be placed until periodontitis is fully under control. In addition, it is essential to remember that the extraction of a tooth with periodontitis does not completely eliminate the pathogens, so these pathogens could rapidly colonise the uncontaminated implants. 

In addition, there are local risk factors that may trigger the disease. A relevant factor is oral hygiene, since bacterial colonisation has already been mentioned as an aetiological factor for periodontitis. It is thus essential to explain to the patient how important good dental hygiene is. In this regard, designing a prosthetic structure that facilitates proper oral hygiene by the patient is necessary (avoid over-contoured prostheses and buccal extensions in hybrid or pontic prostheses located at a distance of under 3 mm from the bone crest)⁽⁸⁾. 

It has also been observed that patients with rough surface implants are more exposed to the disease due to the accumulation of biofilm and bacterial plaque⁽⁹⁾. In spite of this, rough surface implants are still used because they favour osseointegration thanks to the adhesion of the osteoblasts. 

Likewise, it is necessary to watch for excessively deep peri-implant pockets because of overly apical implant placement, since these pockets can store bacteria. On the other hand, the space between the implant and the prosthesis creates an ideal environment for microbial colonisation, so it is important to consider the type of connection between the implant and the prosthesis^(10,11). 

TREATMENT 

In the first place, it is necessary to diagnose and correct any inducing factors (inadequate prosthetic design, buccal extensions, deficient contact points, embrasures, occlusal overload, prematureness, cantilevers or absence of passive adjustment). 

In the case of mucositis, early treatment is essential to reverse the situation. The treatment of mucositis consists basically of eliminating bacterial plaque and instructing the patient in proper oral hygiene. It may be necessary to remove the implant-supported prosthesis to clean it properly. 

Regarding the treatment of peri-implantitis, it is advisable to perform non-surgical treatment in order to reduce inflammation and create a more favourable environment for subsequent surgical treatment. This non-surgical treatment consists of removal of the biofilm by means of mechanical cleaning with the use of curettes and/or abrasive air polishing systems, and a chemical decontamination of the surface of the implant through the application of antiseptics (0.12% chlorhexidine + 0.05% CPC, 3% hydrogen peroxide or povidone iodine) and/or the application of local antibiotics. The subsequent surgical treatment will depend on the morphology of the bone defect: either horizontal or vertical defect; with 1, 2 or 3 walls; circumferential defects, or a combination of the above. Implantoplasty (removal of the threads of the implant) may be done with or without bone regeneration techniques (Figures 1-8). 

All treatment must be done with the commitment of the patient to maintain proper oral hygiene; otherwise, it will be very difficult to obtain good results. 

The University of Valencia Implant Maintenance Unit in Oral Surgery has been established and is currently directed by Professors Maria and David Peñarrocha. This unit applies education to foster prevention, and patients are instructed and held responsible for their oral and implant health. When peri-implant disease is in more advanced stages, treatment programmes, designed according to the specific needs of each patient and using the latest scientifically proven technologies are established. 

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