peri - implant disease may be defined as a pathologic condition including inflammatory and other kinds of lesions affecting the soft and/or hard tissues surrounding a dental implant .
peri - implantitis is characterized by a severe inflammatory process involving both mucosa and bone around the implant .
bone destruction , peri - implant pockets , bleeding on probing , the possible presence of exudate , and loss of supporting tissue are involved in peri - implantitis .
peri - implantitis is due to bacterial contamination or technical problems , related to the implant surface itself or to implant support placement and the subsequent osseointegration process .
osseointegration may be influenced by mistakes or complications occurring in the surgical phase or masticatory overload .
the bacterial biofilm on the implant surfaces is similar to the one in periodontal disease .
the microflora includes microorganisms such as aggregatibacter actinomycetemcomitans , peptostreptococcus micros , campylobacter rectus , capnocytophaga spp .
however , it should be stressed that the residual teeth could influence the composition of microflora .
bacterial species observed in edentulous patients differ from those of partially edentulous subjects . on this basis
, the idea that the presence of bacteria involved in periodontal disease could contribute to development of peri - implantitis seems to be plausible . during the surgical stage ,
the treatment in the initial stage included elimination and of plaque and calculus , decontamination of the implant surface , and maintenance of healthy conditions .
cleaning the surfaces can be through mechanical ( dental curettes , ultrasonic scalers , and air - powder abrasive ) and chemical ( citric acid , h2o2 , chlorhexidine digluconate , and edta ) procedures , in association with local or systemic antibiotics [ 8 , 9 ] .
the most frequently used include diode , erbium lasers , and co2 due to their hemostatic properties , selective calculus ablation , and bactericidal effects .
an alternative approach to dental implant decontamination is the association of the conventional treatment with photodynamic therapy ( pdt ) .
photodynamic therapy includes the use of a low - power diode laser in combination with photosensitizing compounds .
these components are linked to the bacterial membrane and , when excited , react with the substrate .
the photosensitizer binds to the target cells and when it is irradiated with light of specific wavelength , in the presence of oxygen , it undergoes a transition from a low - energy ground state to an excited singlet state ; then singlet oxygen and other very reactive agents are produced , which are toxic to these target cells .
the application of photosensitive dyes into pockets and their activation with light promote killing of periodontal pathogens .
outcomes of clinical studies in subjects with chronic periodontitis show beneficial effects of pdt on the reduction in gingival inflammation .
the effects of pdt on the treatment of ligature - induced peri - implantitis were investigated in dogs .
the results revealed a reduction in bacterial counts of prevotella intermedia / nigrescens , fusobacterium spp . , and beta - haemolytic streptococcus .
several studies have demonstrated bacteria destruction can be achieved without any damage to the treated titanium surfaces .
the aim of this experimental study is to demonstrate the efficacy of antimicrobial photodynamic therapy in addition to the traditional approach .
40 subjects were involved in the study ranging in age from 34 to 68 years , referred to the periodontology department of the dentistry unit at bari university hospital .
the study was conducted following the declaration of helsinki , according to the local ethical committee .
the patients were selected with these inclusion criteria : overall plaque index ( pli ) 40% and at least one implant site with the following characteristics : probing depth ( pd ) 4  mm , bleeding on probing ( bop ) , and presence of suppuration .
exclusion criteria included decompensated systemic disease , degenerative bone disease , chronic immune - based mucomembranous disorders ( e.g. , lichen planus , pemphigoid , pemphigus , and systemic lupus erythematosus ) , chemotherapy or radiotherapy to the head and neck area , pregnancy , presence of teeth with periodontitis adjacent to sites affected by peri - implantitis , implants placed in fresh extraction sockets , smoking > 10 cigarettes daily , and alcoholism .
the null hypothesis was that nonstatistically significant differences are observed with respect to the clinical parameters ( e.g. , ppd , bop , and pli ) between the two treatment modalities ( i.e. , adjunctive pdt test group versus control group ) .
the primary outcome variable was the reduction of pd in peri - implant sites with probing depth 4  mm .
secondary outcome variables were the changes in bop and pli . the ratio of this study was based on the capacity of photodynamic therapy to promote bacterial inactivation by light and not by heat .
360 light irradiation is obtained by means of special probes ensuring optimal light beam diffusion .
the patients were randomly assigned to two groups , that is , a test group ( 63 implants ) and a control group ( 59 implants ) , using a software to create a randomization list ( https://www.random.org/ ) and assigning a code to each patient .
for both groups of patients the following indices were measured by means of a plastic probe : the plaque index ( pli ) , based on the plaque control record ( pcr , ) , bleeding on probing ( bop ) with or without suppuration , and probing depth ( pd ) .
mechanical and manual decontamination of the oral cavity was performed using air polishing with micronized glycine powder to remove plaque and discolorations and expose the underlying calculus ( figure 1 ) .
the latter was removed with a piezoelectric ablator in combination with a universal tip for the scaling of natural teeth and a special nonmetal tip for implant scaling .
root debridement at sites with pd 4  mm was performed with a periodontal ultrasonic unit and implant debridement at sites with pd 4  mm was done with carbon - fiber - reinforced plastic curettes . at the end of the procedure , according to the code of the envelope , the dental hygienist considered in the test group the addition of laser - assisted antimicrobial photodynamic therapy based on the helbo protocol at implant sites with pd 4  mm .
the treatment of pdt was performed using helbo theralite ( bredent medical ) , diode laser battery powered with a wavelength of 670  nm and output of 75  mw / cm , with a spot size of 0.06  cm in diameter .
helbo blue photosensitizer was used , a liquid containing methylene blue ( methylthioninium hydrochloride , also known as 3,7-bis phenothiazine-5-ium chloride ) .
the concentration of photosensitizer was 10  mg / ml with absorbance peak at 670  nm .
its use as a chromophore in photodynamic therapy is justified by its relative stability in the light , which makes it an important generator of singlet oxygen ( et = 142.1  kj / mol with  = 0.60 in water ) .
the photosensitizer was applied inside the peri - implant pocket starting from the bottom and moving in apical - coronal direction ( figure 2 ) .
care was taken to avoid the formation of air bubbles , allowing the fluid to dye all bacteria by leaving it in situ for 60 seconds .
after rinsing the fluid off the pocket and suctioning excess liquid ( figure 3 ) , the previously dyed implant surface was exposed to helbo theralite diode laser for 1 minute ( figure 4 ) .
the fluence was 25.54  j / cm , while the total energy applied was 1592  j / cm .
this type of movement promotes the best activation of the dye molecules with the laser light and transfers their energy to local oxygen .
they were advised to brush their teeth for two minutes , twice a day , using an oscillating - rotating electric toothbrush with little toothpaste and a special brush for interproximal hygiene . 

the same clinical measurements were taken as those at baseline and home oral hygiene instruction was provided again . 

the same clinical measurements were taken as those at baseline and home oral hygiene instruction was provided again .
t3 , end of the study ( 24 weeks ) . the same clinical measurements were taken as those at baseline ( figure 5 ) .
a weighted arithmetic mean was taken to calculate average values for each group in terms of pd , bop , and pli at 6 , 12 , and 24 weeks using a computer software ( graph pad prism 5 ) .
as early as at the 6th week of the study , reductions in clinical parameters were observed in both groups compared with baseline values .
the reduction was first seen as early as at 6 weeks , to be confirmed at 12 weeks , when the values further declined .
test group showed a better value of pd , with an average value of 2  mm if compared with control group ( 3  mm ) . with regard to the plaque index ,
average value was calculated for each group . in this case , a significant score reduction was recorded as early as at the 6th week . despite improving of daily oral hygiene practices ,
regarding bop , at baseline , all patients had bleeding on probing and suppuration at the peri - implant sites under investigation . in the test group patients , these signs of inflammation
had gradually improved to disappear completely by the 24th week . in the control group ,
however , some improvements were recorded , but not all of the patients achieved complete remission ( table 3 ) .
peri - implantitis has been defined as an inflammatory process that affects the soft tissues surrounding an osseointegrated implant in function with concomitant loss of supporting marginal bone .
peri - implant mucositis , in contrast , is a reversible inflammatory reaction of the mucosa adjacent to an implant without bone loss .
colonization of oral implant surfaces with bacterial biofilms occurs rapidly and the biofilm development seems to play an important role in altering the biocompatibility of the implant surface and , thus , enhancing peri - implant disease development .
since photodynamic therapy has been introduced in dentistry , several advantages of laser and pdt in the many fields of dentistry have been described in the literature .
an increasing interest is recently growing regarding pdt in implant dentistry and as a coadjuvant treatment for peri - implantitis .
it employs visible light ( laser ) and a dye ( photosensitizer ) , the combination of which leads to the release of free oxygen radicals , which in turn can selectively destroy bacteria and their products .
although pdt has been used in the field of medicine since 1904 for light - induced inactivation of cells , microorganisms , and molecules , branemark 's discovery of osseointegration in 1965 was extremely important to restorative treatments and , particularly , functional oral rehabilitation .
a large number of patients have been rehabilitated with dental implants , and , consequently , more cases of success and failure have appeared over the years .
it is well known that laser has the ability to modify dentin so as to obtain the exposition of collagen fibers .
this , in turn , may favor a speedy healing and the obtainment of a new collagen attachment in spite of long junctional epithelium .
this fact could explain the faster and greater healing of the wound and the results in the test group .
it is clear that further histological analysis should be carried out to demonstrate this idea .
thus , photodynamic therapy ( pdt ) may be one such treatment alternative . only in the last 10 years or
the current data show that treating chronic periodontitis with pdt alone versus conventional srp treatment has no additional benefit .
in contrast , combining pdt and srp does provide an additional benefit , particularly in lesions with unfavorable anatomic conditions . a clinical controlled study compared the effect of pdt alone ( without subgingival srp ) with srp in the treatment of aggressive periodontitis [ 20 , 21 ] .
in addition to this , during peri - implantitis treatment , helbo technology offers the advantage of a noninvasive , painful , rapid bacterial inactivation thanks to liberation of oxygen .
oxygen allows the destruction of bacteria membrane , and on the other hand its sparkling effect permits dangerous enzymes and collagenosis to be quickly removed from the pocket , for a better bacterial removal and , as a consequence , could facilitate healing .
the improvement of values analyzed was more marked in the test group ( table 1 ) .
test group showed a better value of pd , with an average value of 2  mm if compared with control group ( 3  mm ) .
regarding pli the significant reduction recorded at the 6th week was followed by a slight increase at 12 weeks , with values remaining constant up to the 24th week .
however , the plaque index score for each patient at 24 weeks was anyway lower than at baseline .
finally , a comparison between baseline and final average bleeding on probing ( bop ) and suppuration values also shows substantial improvement .
thus , the results obtained in this study suggest that photodynamic therapy could be considered an effective method for bacterial reduction on implant surfaces [ 1722 ] .
our study also confirms its effectiveness in reducing clinical indices and the bacterial load at sites affected by peri - implantitis , with significant bacterial detoxification being achieved .
photodynamic therapy should , however , be considered a coadjuvant in the treatment of peri - implantitis and associated with mechanical ( scaling ) and surgical ( grafts ) treatments in order to control peri - implant disease .
 
 introduction . 
 the aim of this study is to demonstrate the effectiveness of addition of the antimicrobial photodynamic therapy to the conventional approach in the treatment of peri - implantitis . 
 materials and methods . 
 forty patients were randomly assigned to test or control groups . 
 patients were assessed at baseline and at six ( t1 ) , twelve ( t2 ) , and twenty - four ( t3 ) weeks recording plaque index ( pli ) , probing pocket depth ( ppd ) , and bleeding on probing ( bop ) ; control group received conventional periodontal therapy , while test group received photodynamic therapy in addition to it . 
 result . 
 test group showed a 70% reduction in the plaque index values and a 60% reduction in pd values compared to the baseline . 
 bop and suppuration were not detectable . 
 control group showed a significative reduction in plaque index and pd . 
 discussion . 
 laser therapy has some advantages in comparison to traditional therapy , with faster and greater healing of the wound . 
 conclusion . 
 test group showed after 24 weeks a better value in terms of ppd , bop , and pli , with an average pocket depth value of 2  mm , if compared with control group ( 3  mm ) . 
 our results suggest that antimicrobial photodynamic therapy with diode laser and phenothiazine chloride represents a reliable adjunctive treatment to conventional therapy . 
 photodynamic therapy should , however , be considered a coadjuvant in the treatment of peri - implantitis associated with mechanical ( scaling ) and surgical ( grafts ) treatments . 
1. Introduction
2. Materials and Methods
3. Results
4. Discussion and Conclusion