Key messages
We are very unsure whether adding antimicrobial photodynamic therapy (aPDT) to standard treatment has any important benefits for adults with gum disease when compared to usual treatment alone.
What is gum disease around natural teeth and around dental implants?
Symptoms of gum (periodontal) disease include bleeding gums, swollen gums and bad breath. The infection can damage the soft tissues around the teeth, and in some cases people may lose their teeth. Many people with a dental implant (a false tooth that is fixed in the gum) will be affected by this kind of disease around the implant.
How is gum disease treated?
As well as advice to brush teeth twice a day and regularly floss between teeth, people may need treatment for gum disease from their dentist. Standard periodontal treatment includes scraping any bacteria from the infected areas of the mouth using hand instruments or power-driven instruments. People may also need to take antibiotics, but because of increasing resistance of bacteria to antibiotics, alternative additional treatments may help.
Antimicrobial photodynamic therapy (aPDT) combines a light-absorbing dye (applied to the affected areas of the mouth after bacteria have been removed) and a light source (typically a low-energy diode laser device).
What did we want to find out?
We wanted to find out if aPDT added to standard treatment is more effective than standard treatment alone for people with gum disease. We were interested in the long-term effects of using additional aPDT so we looked at results six months after treatment. We looked at the difference in the depth of pockets (spaces around the teeth caused by gum disease), bleeding (after gentle probing of the affected sites), attachment of the tooth to the bone, the amount of gum that has pulled away from the tooth (gum recession) and how many pockets had closed after treatment. We also wanted to find out if there were any harms associated with using aPDT.
What did we do?
We searched for studies in adults with gum disease or disease around dental implants. We included studies that compared aPDT given after standard treatment versus standard treatment alone. We compared and summarised the results according to whether the treatment was given to people who had never been treated for gum disease (active treatment) or people who were receiving long-lasting care (supportive treatment). We rated our confidence in the evidence based on factors such as study methods and sizes.
What did we find?
We included 50 studies involving 1407 adults. In most studies, aPDT was carried out in a single session. In 11 studies, people had multiple sessions of aPDT (two, three or four sessions). Most studies involved non-smokers. None of the people in the studies had taken antibiotics in the six months before they enrolled in the study. One very small study involved people who had swelling around dental implants. All other studies involved people with gum disease around natural teeth.
What were the main results?
During active treatment of gum disease, we are very unsure whether additional aPDT has any important benefits at six months compared with standard treatment. This includes change in the depth of pockets, bleeding, attachment of the tooth to the bone and gum recession.
We are also very unsure about the findings for the same measurements at six months during the supportive phase of gum disease treatment.
In one study, a participant developed an abscess (a swelling at one tooth), but it is not clear if this was related to aPDT. Other studies observed no harms related to aPDT. No studies reported information about how many pockets had closed six months after treatment.
What are the limitations of the evidence?
We are not confident in the evidence because some studies may not have been well conducted and they included only very small numbers of people. We also found that there were differences between the results of many of the studies and we could not explain what caused this variation.
How up-to-date is this evidence?
This evidence is current to 14 February 2024.
Because the certainty of the evidence is very low, we cannot be sure if adjunctive aPDT leads to improved clinical outcomes during the active or supportive treatment of periodontitis; moreover, results suggest that any improvements may be too small to be clinically important. The certainty of this evidence can only be increased by the inclusion of large, well-conducted RCTs that are appropriately analysed to account for change in outcome over time or within-participant split-mouth study designs (or both). We found no studies including people with peri-implantitis, and only one study including people with peri-implant mucositis, but this very small study reported no data at six months, warranting more evidence for adjunctive aPDT in this population group.
Periodontitis and peri-implant diseases are chronic inflammatory conditions occurring in the mouth. Left untreated, periodontitis progressively destroys the tooth-supporting apparatus. Peri-implant diseases occur in tissues around dental implants and are characterised by inflammation in the peri-implant mucosa and subsequent progressive loss of supporting bone.
Treatment aims to clean the pockets around teeth or dental implants and prevent damage to surrounding soft tissue and bone, including improvement of oral hygiene, risk factor control (e.g. encouraging cessation of smoking) and surgical interventions. The key aspect of standard non-surgical treatment is the removal of the subgingival biofilm using subgingival instrumentation (SI) (also called scaling and root planing). Antimicrobial photodynamic therapy (aPDT) can be used an adjunctive treatment to SI. It uses light energy to kill micro-organisms that have been treated with a light-absorbing photosensitising agent immediately prior to aPDT.
To assess the effects of SI with adjunctive aPDT versus SI alone or with placebo aPDT for periodontitis and peri-implant diseases in adults.
We searched the Cochrane Oral Health Trials Register, CENTRAL, MEDLINE, Embase, two other databases and two trials registers up to 14 February 2024.
We included randomised controlled trials (RCTs) (both parallel-group and split-mouth design) in participants with a clinical diagnosis of periodontitis, peri-implantitis or peri-implant disease. We compared the adjunctive use of antimicrobial photodynamic therapy (aPDT), in which aPDT was given after subgingival or submucosal instrumentation (SI), versus SI alone or a combination of SI and a placebo aPDT given during the active or supportive phase of therapy.
We used standard Cochrane methodological procedures, and we used GRADE to assess the certainty of the evidence. We prioritised six outcomes and the measure of change from baseline to six months after treatment: probing pocket depth (PPD), bleeding on probing (BOP), clinical attachment level (CAL), gingival recession (REC), pocket closure and adverse effects related to aPDT. We were also interested in change in bone level (for participants with peri-implantitis), and participant satisfaction and quality of life.
We included 50 RCTs with 1407 participants. Most studies used a split-mouth study design; only 18 studies used a parallel-group design. Studies were small, ranging from 10 participants to 88. Adjunctive aPDT was given in a single session in 39 studies, in multiple sessions (between two and four sessions) in 11 studies, and one study included both single and multiple sessions. SI was given using hand or power-driven instrumentation (or both), and was carried out prior to adjunctive aPDT. Five studies used placebo aPDT in the control group and we combined these in meta-analyses with studies in which SI alone was used.
All studies included high or unclear risks of bias, such as selection bias or performance bias of personnel (when SI was carried out by an operator aware of group allocation). We downgraded the certainty of all the evidence owing to these risks of bias, as well as for unexplained statistical inconsistency in the pooled effect estimates or for imprecision when evidence was derived from very few participants and confidence intervals (CI) indicated possible benefit to both intervention and control groups.
Adjunctive aPDT versus SI alone during active treatment of periodontitis (44 studies)
We are very uncertain whether adjunctive aPDT during active treatment of periodontitis leads to improvement in any clinical outcomes at six months when compared to SI alone: PPD (mean difference (MD) 0.52 mm, 95% CI 0.31 to 0.74; 15 studies, 452 participants), BOP (MD 5.72%, 95% CI 1.62 to 9.81; 5 studies, 171 studies), CAL (MD 0.44 mm, 95% CI 0.24 to 0.64; 13 studies, 414 participants) and REC (MD 0.00, 95% CI -0.16 to 0.16; 4 studies, 95 participants); very low-certainty evidence. Any apparent differences between adjunctive aPDT and SI alone were not judged to be clinically important. Twenty-four studies (639 participants) observed no adverse effects related to aPDT (moderate-certainty evidence). No studies reported pocket closure at six months, participant satisfaction or quality of life.
Adjunctive aPDT versus SI alone during supportive treatment of periodontitis (six studies)
We were very uncertain whether adjunctive aPDT during active treatment of periodontitis leads to improvement in any clinical outcomes at six months when compared to SI alone: PPD (MD -0.04 mm, 95% CI -0.19 to 0.10; 3 studies, 125 participants), BOP (MD 4.98%, 95% CI -2.51 to 12.46; 3 studies, 127 participants), CAL (MD 0.07 mm, 95% CI -0.26 to 0.40; 2 studies, 85 participants) and REC (MD -0.20 mm, 95% CI -0.48 to 0.08; 1 study, 24 participants); very low-certainty evidence. These findings were all imprecise and included no clinically important benefits for aPDT. Three studies (134 participants) reported adverse effects: a single participant developed an abscess, though it is not evident whether this was related to aPDT, and two studies observed no adverse effects related to aPDT (moderate-certainty evidence). No studies reported pocket closure at six months, participant satisfaction or quality of life.