Number (n) of culture-positive implants at baseline and culture-negative after selected bacteria decontamination with photodynamic therapy.
Different titanium implant surfaces are prone to microbial colonization and dental plaque accumulation contributing to peri-implantitis pathogens adherence and growth. In conjunction with systemic, local, and implant-based factors such as micro- and macro-designs, implant location, and region, these pathogens can cause a complex inflammatory response resulting in peri-implantitis and deleterious bone loss. Implant surface decontamination plays a crucial and important step in peri-implantitis therapy. The primary goal of implant surface decontamination is to eradicate bacteria and their products outside of implant pits and grooves reducing inflammation and promoting tissue regeneration and/or reparation. Various implant surface decontamination methods such as mechanical, chemical or physical methods have been proposed to prevent bacterial resistance development or/and surface damage. The chapter aimed to assess if implant microdesign could influence the decontamination method choice.
- implant design
- implant surface
- decontamination methods
- peri-implantitis therapy
Dental implants have become highly predictable routine therapeutic strategy in daily practice for a missing teeth replacement in the partial or total edentulous patients’ treatment.
Osseointegration presents close bone-to-implant contact (BIC) and depends on several factors such as implant micro- and macro-design which play crucial roles in long-term implant survival success rate. Implant macro-construction (implant shape, number and shape of implant threads) is designed to improve osseointegration mechanism and obtain implant primary stability resisting detrimental forces occurring during physiological functions [1, 2, 3, 4]. Various implant surfaces were developed to enhance osseointegration mechanism accelerating and strengthening bone formation providing better stability . Additional modification of implant surfaces increases surface roughness with aim to improve bone healing especially in the region with poor bone quantity or quality stimulating bone growth, and enabling immediate or early loading protocols . This modification increases surface roughness as well, making it another important parameter for effective osseointegration.
The mechanism of osseointegration could invert unpredictably into a pathological process leading to inflammatory reactions in soft tissue (peri-mucositis) or a subsequent bone loss around an osseointegrated implant. This process could cause peri-implantitis onset, and as consequence implant failure [7, 8, 9]. As a disease of the modern era, peri-implantitis is defined as a plaque-associated pathological condition characterized by clinical signs of inflammation such as bleeding on probing (BOP) with or without suppuration, peri-implant probing depths increase (PPD), and clinical attachment loss (CAL) along with radiographic bone loss .
Major aetiological factors in the peri-implantitis development are virulent pathogenetic anaerobic bacteria (
In addition, a myriad of patient-related factors (genetic, diabetes mellitus, cardiovascular diseases, genetics, smoking), local factors (periodontitis, residual cement, poor oral hygiene, etc.), and implant-based factors are introduced as risks that could induce onset and severity of peri-implantitis [8, 14, 15, 16, 17, 18].
1.1 Implant-based and implant-related factors in peri-implantitis
1.1.1 Implant macro-design associated with peri-implantitis
Specific implant topography, i.e., its macro-design such as body shape, threads number, and collar design as well as micro-design aimed to speed the process of osseointegration enabling a rapid implant loading . However, these dental implant components themselves could be addressed as one of the implant-based risk factors associated with peri-implantitis onset.
A variety of commercially available implants with cylindrical or conical body shape, one-, double- or triple-threads number and different thread shapes are constructed not only to accelerate the osseointegration process but also to minimize a hazard shear force acting instantaneously. Moreover, the implant macro-design aimed to prevent additional further marginal bone loss that could jeopardize implant long-term stability after prosthetic rehabilitation. In contrast, cylindric implants and implants with triple-threads demonstrated the production of greater detrimental shear forces  resulting in higher bone loss with implant failure, respectively.
To speed up and shorten implant placement by increasing the threads number on the implant body (double- and triple-thread) could, unfortunately, induce more pressure forces . This resulted in increased bone loss, especially at triple-threads compared to single-thread . In a laboratory model, using finite element analysis (FEA), threads shape was used to stimulate and estimate stress distribution between implants and cortical or cancellous bone  indicating that “V” shape and a broader-square shape generated less stress in cancellous bone than other examined threads. In contrast, implants with “V” and butter thread shapes generated higher forces that induced bone defect formation [20, 21], and may consequently contribute to peri-implantits. Although these facts arising from
Implant macro-design could also cause excess cement retention that could act as rough surface facilitating an adherence of microorganism and inflammation around peri-implant mucosa with subsequent bone loss. Moreover, other implant-based factors such as implant-abutment connection type, prosthetic rehabilitation, and occlusal overload, could also be taken into consideration as risks for peri-implantitis onset [8, 18, 26, 27, 28].
Since the current literature are insufficient in providing evidence whether the implant macrodesign parameters such as implant body shape and dimension, and threads number could be the possible risk factors associated with the initiation and progression of peri-implantitis, further studies are required.
1.1.2 Implant micro-design in correlation with peri-implantitis onset
Over the last few decades, implant surfaces topography has been modified to enhance BIC rates, primary implant stability as well as positive host-to-implant response aiming to attain long-term implant treatment success rates. Bone response to implant topography modification has been specifically related to surface roughness, surface free energy and surface chemistry.
The implant’s surface could be “smooth” (machined) or rough. Roughness Average (Ra) or Arithmetical Mean Height (Sa) parameters are used to describe the roughness of dental implant surfaces referring to the height of the surface structure in two or three dimensions. Mostly, implant surface roughness could be divided into four groups: smooth implant surface with Sa roughness value less than 0.5 μm, minimally rough surface (Sa value 0.5–1.0 μm), moderately rough surface (Sa value 1.0–2.0 μm), and rough surface (Sa value more than 2.0 μm). Several methods are reported in the literature to create implant roughness including acid etching, sandblasting, titanium plasma spraying, and hydroxyapatite (HA) coating, contributing to changes in implant physicochemical properties [5, 29, 30]. Currently available dental implant systems could have either moderately rough surfaces such as SLA, TiUnite, OsseoSpeed, and TiOblast implants or a rough surface such as Ankylos, IMZ or TPS implants . Nevertheless, these implant topography features may play a role in peri-implantitis onset [5, 29, 31].
A study by Polizzi and al. demonstrated that peri-implantitis was more commonly detected at implants with a rough TiUnite surface compared with the minimally rough machined surface . Furthermore, the spontaneous and greater bone loss occurred at the implants with a TiUnite surface compared to Turned, SLA or TiOblast surfaces [33, 34, 35]. The hazardous effect of TiUnite surface could be explained by its microdesign and the presence of grooves and pits that might encourage bacterial adhesion . Although microbial plaque accumulation had been detected on novel modified anodized surfaces (TiUltra), this surface affected minimal bone loss and inflammation resulting in marginal bone stability . Additionally, zirconium surface promoted plaque reduction
Implant roughness and surface free energy influenced the dental plaque accumulation and biofilm formation inducing peri-implantitis [37, 38]. According to a literature review by Teughels et al.  increasing surface roughness above 0.2 μm resulted in biofilm formation and bacteria adhesion. Despite differences in surface roughness, another
The development of bioactive titanium surface coatings with antibacterial properties has been considered as an additional strategy for controlling biofilm formation . Different antimicrobials, active molecules, compounds, and ions were incorporated into implant surface to stimulate bactericidal or/and bacteriostatic effect on surrounding tissue decreasing in this way bacterial adhesion on implant surface. Unfortunately, this strategy has a short-term effect since the remains of dead cells on the uncleaned surfaces may act as bridges for bacteria coaggregation and colonization  leading to possible peri-implantitis onset.
1.2 Other peri-implantitis risk factors
Other risk factors such as smoking, diabetes, medications used in the treatment of chronic diseases may influence bone metabolism supporting plaque accumulation and adversely impacting the periimplant-tissue response. Despite limited evidence, survival of implants in patients with diabetes could be disturbed by high blood glucose level, that affects the immune system impairing tissue repair and host defenses against dental plaque , therefore accelerating peri-implantitis development or progression. Special caution in the peri-implantitis treatment should be advised in patients with chronic disorders/ diseases.
2. Treatment of peri-implantitis
Peri-implantitis is a complex multi-microbial and multifactorial disease, thus, therapy continues to be a challenge. It has been suggested that peri-implantitis surgical therapy is superior to non-surgical one . Implant surface decontamination is an important but at the same time difficult step in peri-implantitis treatment. The goal of implant surface decontamination is to completely remove all causative bacteria from the implant surface preparing the tissue for regeneration and re-osseointegration . Considering the possible role of micro- and micro-design on peri-implantitis initiation, special care should be taken in the process of implant surface decontamination.
The removal of microbes from the implant surface may cause possible implant surface damage. As a result of surface damage, surface chemical oxide layer changes could lead to induced corrosion, acidic pH, changes in surface roughness, plaque accumulation, and osteoclast activation impairing implants biocompatibility . Additionally, different methods of decontamination could generate mechanical or chemical processes on implant surfaces releasing titanium’ ions and particles, and promoting the pathogenic biofilm growth on treated surfaces as well .
Although there is no standardized protocol for peri-implantitis treatment, many methods of implant surface decontamination have been proposed including mechanical methods, chemical methods, laser, photodynamic therapy, and implantoplasty, usually combined with systemic antibiotics administration [51, 52, 53, 54, 55, 56, 57, 58, 59, 60]. Accordingly, this chapter aimed to determine which method of implant surface decontamination could be successfully performed assessing comparably if implant topography could have influenced the decontamination method choice in peri-implantitis treatment.
2.1 Mechanical and chemical methods of implant surface decontamination
The removal of biofilms and calculus is essential for long-term clinical success and bone regeneration . Therefore, mechanical removal of granulation tissue and surface cleaning presents the first steps in peri-implantitis or periodontal therapy. Ideal mechanical methods should be capable of completely removing deposits and bacteria along with their products from the implant surface without altering or damaging implant surface integrity and biocompatibility, or affecting the implant-tissue interface. Due to implant surface macro- and micro-design as well as bacterial characteristics, it is difficult to achieve long-term results using a mechanical method alone. Therefore, this method is usually combined with chemical methods, photodynamic or laser therapy.
Several instruments such as curettes and brushes have been proposed for mechanical implant surface decontamination. Metal (stainless steel) curettes, burs and conventional sonic and ultrasonic scalers, have been shown to damage the smooth or rough (TPS and SLA) implant surface leaving behind the debris by removing the surface coating, threads and edges. Nevertheless, these instruments are only used when smooth surface of implant, implantoplasty, is required . Titanium curettes were also advised to be used with caution due to their tendency to leave marks on the implant surface increasing the depth of the surface roughness and in this way causing an inability to effectively remove biofilm . Plastic curettes did not leave any surface scratches on different implants surfaces. However, their limited flexibility and size resulted in incomplete plaque removal in screw-type implants . Even when combined with chemical methods such as chlorhexidine gluconate (CHX), plastic curette was not effective in biofilm removal from Osseotite® or SLA titanium disks  thereby only being recommended for use during maintenance care .
Peri-implantitis treatment performing the Vector system improved oral hygiene, yet showing no improvement in clinical parameters compared to carbon curettes after six months of follow-ups . According to systematic reviews, Vector systems with carbon tips efficiently removed biofilms from polished titanium and SLA surfaces. Hence, the potential to produce SLA and TPS surface damage was found to be a drawback, and could be possible explanation for poor clinical outcomes [61, 63, 67].
The market offers a variety of rotating titanium brushes that are successfully used in combination with other chemical agents or physical methods for implant surface decontamination (Figure 1). Rotating brushes effectively clean SLA, TiUnite, and OsseoSpeed surfaces without compromising their properties . Contrary to this,
Other mechanical methods of implant surface decontamination, air powder-water sprays, have not shown to be superior in terms of improvement in clinical parameters and possible re-osseointegration compared to other mechanical methods. Recent
Implantoplasty is another mechanical method of implant surface decontamination that is usually used during surgical peri-implantitis therapy to smoothen the supracrestal exposed implant surface (Figure 2). Whenever there is a persistent supracrestal bone defect (Class II bone defect, classified by Schwarz ), implantoplasty appears to be the most effective treatment. Among the benefits of implantoplasty there is a very low bacteria adhesion and recolonization rate.
Due to the implant surface roughness, it could not be possible to remove bacteria and their waste products completely. Therefore, it is recommended to be combined with antiseptics and antibiotics. Various chemical agents such as chlorhexidine gluconate (CHX), hydrogen peroxide (H2O2), citric acid, and phosphoric acid have been proposed as means to decontaminate titanium implant surfaces in both non-surgical and surgical therapies.
The CHX is a commonly used antiseptic agent that is considered a ‘gold standard’ in various treatment procedures. It is a time-dependent chemical agent which exhibits both bactericidal and bacteriostatic effects. With increasing CHX concertation, in both pure titanium discs and titanium-zirconium alloy discs there was a decrease in the mean number of colony-forming units indicating antibacterial dose–response and biofilm control . Even so, the clinical and microbiological outcomes in one of RCTs had not shown statistical differences when two CHX concentrations (2% vs. 0.12% CHX + 0.5% CPC) were used for the decontamination of commercially available implant surfaces during peri-implantitis resective surgery . These results were consistent with our prior published study in which implant surface decontamination was performed by applying 1% gel of CHX followed by saline solution irrigation during regenerative surgery. Our study concluded that this chemical procedure had insufficient effectiveness in clinical and microbiological results . Under
The use of adjuvant systemic or local antibiotic therapy could also be affected by implant surface topography in peri-implantitis therapy. A successful treatment outcome was documented in only 45% of treated implants by Carcuac et al. In this study, 79% of implants with non-modified surface features and 34% of implants with modified surfaces had successful treatment after peri-implant surgery . In the Heitz-Mayfield et al. study, a significant improvement of clinical parameters was achieved within 12 months after an open-flap surgical procedure of moderate and advance peri-implantitis followed by adjuvant systemic antibiotics administration (amoxicillin and metronidazole) and antiseptic solution (0.12% CHX). Approximately 47% of implants with various surface topographies completely resolved inflammation postoperatively. However, within 12 months of implant surgery, bone continues to lose on implants with porous anodized, titanium plasma-sprayed, and machine surfaces . Systemic antibiotics had limited penetration into the biofilm attached to the titanium implant surface. These findings would support the recommendation that implant surface should be carefully evaluated prior to adjuvant systemic antibiotics administration. Apart from this, broad-spectrum antibiotics’ excessive use, their side effects, and allergic reactions have led to bacterial-resistance development, thus additional care should be taken in their administration.
In order to overcome these drawbacks of chemical and mechanical methods, novel methods such as laser or photodynamic therapy were introduced to improve implant surface decontamination.
2.2 Application of laser and photodynamic therapy in peri-implantitis treatment
2.2.1 Laser use in peri-implantitis therapy
In the late 1980’s, a laser system was introduced in dentistry  increasing laser popularity in dental implantology considerably. Due to the laser’s capacity to achieve satisfactory cutting, induce good coagulation, and antibacterial effect, the laser is widely used in dental implantology for the safe second stage surgery of submerging implants, peri-implant soft tissue plastic surgery, and implant surface decontamination. Lasers have been described to possess ability to facilitate implant site preparation enhancing bone healing and osseointegration [56, 77, 78].
The lasers’ use in non-surgical and surgical peri-implantitis therapy was widely examined, especially its effects on implant surface decontamination and re-osseointegration. Titanium implant surfaces have greater absorption characteristics resulting in the surface overheating and alteration, so special consideration should be given when they are exposed to the laser. A literature review has recommended a few types of lasers for decontaminating implant surfaces .
Er: YAG laser is suggested for successful implant surface decontamination with a tendency to achieve re-osseointegration (Figure 3). Safe irradiation settings for this laser should be above 300 mJ/10 Hz for 10s achieving efficiently a bactericide effect, and not increasing implant temperature or altering the surface of polished or SLA implants . Favorable long-term outcomes following treatment of peri-implantitis with Er: YAG lasers were observed in a few clinical studies [80, 81]. A case report study on zirconium implants found that Er: YAG led to improvements in clinical parameters (PPD and BOP) six months after peri-implantitis surgery .
CO2 (carbon dioxide laser) and gallium-aluminum-arsenide lasers (one of the diode lasers) are introduced as safe methods for implant decontamination with antibacterial effects. Depending on implant surface topography, special attention should be taken considering the time of laser exposure, power, and irradiation mode (continues, CW, or pulse, PW, mode).
On the other hand, Nd: YAG lasers could induce surface alteration by causing surface melt and increasing its roughness. This type of laser is contraindicated for any dental implant surgical interventions. Application of diode lasers with other wavelengths or fiber systems should be used with special care as the laser light directly contacting the bone may cause thermal damage.
2.2.2 Photodynamic therapy assessment in peri-implantitis therapy
A novel antimicrobial treatment modality, photodynamic therapy (PDT) was introduced for the various oral infection treatments. The PDT mechanism is based on a suitable wavelength low-energy single-frequency diode laser activating a photoactive material (photosensitiser) that binds a target cell. In this mechanism, the photochemical oxygen-dependent reaction is induced producing very reactive superoxide radicals, such as single oxygen that causes photogenic species death.
Studies demonstrated the PDT efficiency in treating peri-implantitis with a particular emphasis on implant surfaces decontamination using the procedure (Figure 4). A few
In our previous clinical study, the positive effects of PDT on microbiological reduction and clinical outcomes improvement after peri-implantitis surgery were assessed three months postoperatively . PDT proved to be a very effective decontamination method for various titanium implant surfaces according to the research. Additionally, the further follow-up observation aimed to show the maintenance results achieved by performing PDT, six and 12 months postoperatively. Patients’ inclusion criteria, follow-up parameters and surgical treatment procedures have previously been reported in detail . In brief, the surgical regenerative treatment procedure was performed on each patient with early or moderate peri-implantitis. During the surgery, after careful mucoperiosteal flap elevation, granulation tissue removal, patients were randomly divided into two groups. In one group (21 systemically healthy patients), PDT (HELBO, Photodynamic Systems GmbH, Wels, Austria) was performed for implant surface decontamination, while in another group (19 systemically healthy patients), CHX was used as a chemical decontamination method. Clinical and microbiological outcomes were used to assess treatment success. Microbiological samples were taken both from the pockets around the implant prior to any procedure and during follow-ups, and during surgical procedures before and immediately after surface decontamination. Samples were cultured and biochemically analyzed using standard procedures for anaerobic bacteria diagnosis. Detailed microbiological sample collecting and analyses were explained in the previous study . The results were examined using SPSS 20.0.
Different pathogenic bacteria (Table 1) were isolated either from various examined implant surfaces (Table 2) during the surgical therapy or from the peri-implant pockets prior to any treatment. The presence of
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|Implant surface||Number (N)|
|Acid washed surface, MTX||10%|
|Titanium-oxide layer, TiUnit||47%|
|Machined polished surface||27%|
One of the goals in peri-implantitis therapy is the total elimination of pathogens allowing the tissue to regenerate. As a final result, re-osseointegration is considered to be an essential outcome of peri-implantitis treatment that may be affected by different implant surface decontamination protocols. Experimental outcomes demonstrated partial peri-implant defect reconstruction and re-osseointegration after performing PDT for SLA implant surface decontamination combined with or without guide bone regeneration (GBR) and collagen membrane . One of the earliest experimental studies evaluated the ability of PDT to re-osseointegrate peri-implantitis defects around a variety of implant surfaces utilizing GBR and polytetrafluoroethylene membrane . Study results indicated that the TPS surface showed a greater re-osseointegration rate than HA implant surface. Based on these findings, PDT may have potential effects in peri-implantitis treatment with a potential to lead to re-osseointegration. Different bone grafts application in filling peri-implant defects might contribute to clinical outcomes improvement that may be an explanation for earlier interpreted clinical results.
Nevertheless, decontamination of implant surfaces aims to recreate the conditions that existed before infection or after the implant was placed and integrated. Hence, in order to achieve re-integration, and considering implant topography as well, both micro- and macro-design need to be almost identical to what existed before the implant was placed enhancing osteoblast stimulation and creating re-novel BIC. Accordingly, peri-implantitis requires special consideration in determining the appropriate decontamination methods since there are no standard treatment protocols. Consequently, more clinical trials are required to determine the efficacy of proposed decontamination methods for implant surfaces, with or without regenerative and resective methods.
Implant micro- and macro-design could be possible risk factors in peri-implantits onset or progression. Various implant surfaces may lead to peri-implantitis. In addition, choosing the right decontamination method could be influenced by the very implant surface. Mechanical methods coupled with PDT or a chemical method such as CHX and H2O2 may be effective in peri-implantitis treatment. Antibiotics administration in peri-implant treatment, on the other hand, must be taken with caution. Laser decontamination of implant surfaces is indicated provided that all parameters necessary for successful treatment are respected.
Conflict of interest
The authors declare no conflict of interest.