Photodynamic therapy for the treatment of peri-implant diseases: A network meta-analysis of randomized controlled trials

Highlights

• This network meta-analysis generates evidence in the absence of clinical trials using common comparator.

• The utility of photodynamic therapy is compared with local drug delivery and mechanical debridement for peri implantitis based on existing clinical evidence.

• This forms the basis for future clinical trials which should be of high quality, randomized and investigating into other treatment options for peri implantitis compared with photodynamic therapy.

Abstract

Background

Photodynamic therapy in peri-implantitis has been tested in randomized clinical trials. Though systematic review and meta-analysis on human and animal studies, identifies the utility of photodynamic therapy, a comparison of other interventions with photodynamic therapy for peri-implantitis does not exist. Hence the aim of this network meta-analysis is to identify the role of photodynamic therapy for peri-implantitis compared with other interventions tested in randomized human clinical trials.

Method

Randomized controlled trials comparing photodynamic therapy and other interventions in patients with peri- implantitis was searched for in electronic databases. The risk of bias was calculated using Cochrane risk of Bias tool. The heterogeneity between the studies in direct comparison was assessed using Chi-square and I² tests. GRADE working group approach was used to assess the quality of evidence. Publication bias was assessed using Funnel plot and Trim and Fill method was used to identify the number of missing studies.

Results

We observed a significant reduction in the level of attachment scores with the use of combined photodynamic therapy with mechanical debridement when compared with other interventions tested. For bleeding on probing, pocket depth and plaque scores no statistically significant results were obtained.

Conclusion

The use of photodynamic therapy with mechanical debridement will definitely bring about significant improvement in patients with peri-implantitis. Further trials on the use of photodynamic therapy with other treatment modalities need to be tested to arrive at the best possible treatment option for peri-implantitis.

Introduction

The increase in the use of dental implants has concomitantly increased the frequency of implant related complications. The most common complication is peri-implantitis reported at a frequency of 1–47% [1]. Peri-implantitis is characterised by severe inflammation resulting in significant destruction of bone and mucosa surrounding the implant. The possible aetiology is the presence of bacterial biofilm on the surface of implants. A systematic review presents various surgical and non-surgical modalities that are tested for the treatment of peri-implant diseases [2]. The non-surgical techniques include mechanical debridement, local drug delivery and anti-infective therapy and implant surface decontamination [3]. One such implant surface decontamination technique, which is a non-surgical modality, is the use of photodynamic therapy. The focus of using this therapy include infection control and detoxification of implant surfaces which leads to regeneration of lost tissues without surgical or flap elevation [4]. Photodynamic therapy, also called photoradiation therapy, phototherapy or photochemotherapy, indicates the use of low power laser in combination with an appropriate photosensitiser [4]. Mechanical instruments other than titanium used to clean bacterial deposits or plaque might damage the surface of implants [5]. The use of photodynamic therapy to treat peri-implantitis has been tested in various clinical studies in comparison with other modalities like local drug delivery and mechanical debridement [6], [7]. The components of this system include laser, oxygen and a photosensitiser. On exposure to light the photosensitiser can react directly either with the substrate, such as the cell membrane or a molecule, transferring a hydrogen atom to form radicals. The radicals interact with oxygen to produce oxygenated products. This is called type I photodynamic therapy reaction [8]. Alternatively, type II reaction is that the activated sensitizer transfers its energy directly to oxygen, to form singlet oxygen which is a highly reactive oxygen species. These species oxidize various substrates thereby causing killing and destruction of microorganisms [8]. This effect is more pronounced against gram positive organisms due to the cell wall structure [8], [9]. Methylene Blue and toluidine blue have been most commonly used photosensitisers against peri-implantitis pathogens. Other hydrophobic compounds include porphyrins, chlorins, and phthalocyanines [10]. The bactericidal effect of this therapy not only is dependent on the photosensitiser used but also on the wavelength of the light source, dose and also on the targeted species [11]. The most commonly used light sources include laser and non-laser sources like halogen and light emitting diode and visible light with water filtered infrared [11]. Systematic reviews and meta-analysis in the past attempted to identify the use of photodynamic therapy in the treatment of peri-implantitis [12], [13], [14]. However a comparison of photodynamic therapy with other interventions for peri-implantitis was not attempted. Network meta-analysis has the advantage of comparing interventions in the absence of clinical trials by using a common comparator and to identify the best amongst the pool of agents in the absence of clinical trials. The focussed PICO based research question is: In patients with peri-implantitis, in comparison with photodynamic therapy, which is the best possible intervention as regards to the treatment outcome measures which are level of attachment, pocket depth, bleeding on probing and plaque scores. Hence the aim of this network meta-analysis using Bayesian approach is to compare other interventions with photodynamic therapy on the treatment of peri-implantitis based on existing clinical trials. This meta-analysis is reported and presented in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) guidelines [15].