Available via license: CC BY
Content may be subject to copyright.
Citation: Opšivaˇc, D.; Musi´c, L.;
Badovinac, A.; Šekelja, A.; Boži´c, D.
Therapeutic Manuka Honey as an
Adjunct to Non-Surgical Periodontal
Therapy: A 12-Month Follow-Up,
Split-Mouth Pilot Study. Materials
2023,16, 1248. https://doi.org/
10.3390/ma16031248
Academic Editor: Lia Rimondini
Received: 10 December 2022
Revised: 15 January 2023
Accepted: 28 January 2023
Published: 1 February 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
materials
Article
Therapeutic Manuka Honey as an Adjunct to Non-Surgical
Periodontal Therapy: A 12-Month Follow-Up, Split-Mouth
Pilot Study
David Opšivaˇc 1, Larisa Musi´c 2, Ana Badovinac 2, An ¯
delina Šekelja 3and Darko Boži´c 2,4,*
1School of Medicine, University of Pula, Zagrebaˇcka 30, 52100 Pula, Croatia
2Department of Periodontology, School of Dental Medicine, University of Zagreb, Gunduliceva 5,
10000 Zagreb, Croatia
3Health Center Zagreb, Runjaninova 4, 10000 Zagreb, Croatia
4University Dental Clinic, University Hospital Centre Zagreb, Kišpati´ceva 12, 10000 Zagreb, Croatia
*Correspondence: bozic@sfzg.hr; Tel.: +385-14802202
Abstract:
Periodontitis is recognized as one of the most common diseases worldwide. Non-surgical
periodontal treatment (NSPT) is the initial approach in periodontal treatment. Recently, interest has
shifted to various adjunctive treatments to which the bacteria cannot develop resistance, including
Manuka honey. This study was designed as a split-mouth clinical trial and included 15 participants
with stage III periodontitis. The participants were subjected to non-surgical full-mouth therapy,
followed by applying Manuka honey to two quadrants. The benefit of adjunctive use of Manuka
honey was assessed at the recall appointment after 3, 6, and 12 months, when periodontal probing
depth (PPD), split-mouth plaque score (FMPS), split-mouth bleeding score (FMBS), and clinical
attachment level (CAL) were reassessed. Statistically significant differences between NSPT + Manuka
and NSPT alone were found in PPD improvement for all follow-up time points and CAL improvement
after 3 and 6 months. These statistically significant improvements due to the adjunctive use of Manuka
amounted to (mm): 0.21, 0.30, and 0.19 for delta CAL and 0.18, 0.28, and 0.16 for delta PPD values
measured after 3, 6, and 12 months, respectively. No significant improvements in FMPS and FMBS
were observed. This pilot study demonstrated the promising potential of Manuka honey for use as
an adjunct therapy to nonsurgical treatment.
Keywords: periodontitis; manuka honey; nonsurgical periodontal therapy
1. Introduction
Periodontitis is a chronic inflammatory disease affecting the teeth’s supporting ap-
paratus. Bacterial biofilm and the associated periodontal pathogenic bacteria, mainly
Gram-negative anaerobes, are the main etiological factor of the disease [1].
The main goal of periodontal treatment is to reduce the number of periodontal
pathogens and arrest the inflammatory process. The contemporary gold treatment standard
is non-surgical periodontal therapy (NSPT), which involves scaling and root planning using
manual and machine-driven (sonic or ultrasonic) instruments [
2
]. The literature suggests
that this therapy is highly effective in eliminating the infection. The latest systematic review
article by Suvan et al. on subgingival instrumentation for periodontitis treatment estimates
a weighted range of pocket depth reduction of 1.0–1.7 mm and a ratio of pocket closure of
57–74% after 3/4 and 6/8 months, respectively, that was achieved through non-surgical
periodontal treatment only [
3
]. Although NSPT can effectively reduce the number of peri-
odontal pathogens, microbial recolonization commonly occurs, and residual pockets are
expected to remain after NSPT [2].
Materials 2023,16, 1248. https://doi.org/10.3390/ma16031248 https://www.mdpi.com/journal/materials
Materials 2023,16, 1248 2 of 10
Various systemically administered and locally delivered adjuncts to NSPT have been
suggested, including systemic and local antibiotics, antiseptics, probiotics, lasers, and pho-
todynamic treatment. However, the latest guidelines on the treatment of periodontitis stage
I–III do not support the use of adjuncts. The exception in terms of open recommendations
is given for locally administered sustained-release chlorhexidine and antibiotics and the
use of systemic antibiotics in specific patient groups [2].
The fact that bacteria are becoming increasingly resistant to antibiotics and antiseptics
has shifted the interest of medicine to alternative treatment methods against which bacterial
resistance cannot be developed. This approach includes using honey, which is increasingly
used in medicine. Since the 1990s, when the first studies appeared on the therapeutic
effects of honey, particular interest has been focused on its antibacterial properties against
infections and antibiotic-resistant bacteria. This effect is consequential mainly of the high
sugar concentration of honey, its low pH value, and the formation of hydrogen peroxide
that occurs in the enzymatic breakdown of glucose by the glucose oxidase enzyme [
4
].
Contemporary research on the effects of honey focuses predominantly on one specific honey
type, leading to the medicinal use of Manuka honey due to its antibacterial properties [
5
].
This is an endemic type of honey produced by bees in Australia and New Zealand from the
flowers of the plant Leptospermum scoparium [6].
The concentration of hydrogen peroxide in Manuka honey is lower than in other types
of honey [
7
]. The specific antibacterial activity in Manuka honey is based on methylglyoxal
(MGO), a compound proven to be a very efficient bactericide, virucide, and fungicide.
Furthermore, Manuka honey is highly effective against antibiotic-resistant bacteria [
8
]. The
antibacterial potency of Manuka honey was found to be related to its Non-Peroxide Activity
(NPA), trademarked as Unique Manuka Factor (UMF) rating, a classification system which
reflects the equivalent concentration of phenol (%, w/v) required to produce the same
antibacterial activity as honey, and it is correlated with the methylglyoxal and total phenols
content [
9
]. In addition to its antimicrobial properties, published literature suggests that
MGO also has immunomodulatory effects which may positively impact wound healing
and tissue regeneration [10,11].
Therapeutic Manuka honey has not yet been investigated as a possible adjunct to NSPT.
Therefore, this pilot study aims to evaluate the effects of a product containing Manuka
honey on periodontal parameters when applied to periodontal pockets after nonsurgical
periodontal treatment in patients with stage 3 periodontitis.
2. Materials and Methods
2.1. Experimental Design
This study was designed as a single-center prospective pilot trial with a 12-month
follow-up. A split-mouth study model was used. Two quadrants were randomly assigned
to the test treatment of NSPT + product containing Manuka honey or NSPT-only.
This pilot study was approved by the Ethics Committee of the School of Dental
Medicine, University of Zagreb, Croatia; approval No. 05-PA-30-IX-9/2019. All parts of the
study were conducted in full accordance with the World Medical Association Declaration
of Helsinki on ethical principles for medical research involving human subjects.
2.2. Population Screening and Inclusion
Patients who sought or were referred for periodontal therapy at the Clinical Depart-
ment of Periodontology, University Hospital Zagreb, between September 2019 and March
2021, were screened for possible inclusion in the study. The inclusion criteria were: (1) sys-
temically healthy patients of both genders, between the age of 18 and 70; (2) non-smokers;
(3) presence of at least 20 teeth; and (4) untreated generalized advanced chronic periodon-
titis according to the 1999 Classification 1999 [
12
], i.e., generalized stage III periodontitis
according to the 2007 Classification [
13
]. Exclusion criteria were: (1) pregnant and nursing
women; (2) antibiotics prescribed for dental or non-dental diseases six months before the
start of the research; (3) systemic diseases or the use of drugs known to affect periodontal tis-
Materials 2023,16, 1248 3 of 10
sues; and (4) acute oral or periodontal inflammation or infection (pericoronitis, necrotizing
periodontal diseases, etc.). Following inclusion, a periodontal examination was performed
by one calibrated periodontist (D.B.). Assessments were done at six sites using a UNC-15
periodontal probe (HuFriedy, Chicago, IL, USA). The following parameters were measured
and recorded: probing pocket depth (PPD), recession of the gingival margin (REC), clinical
attachment loss (CAL; calculated as the sum of PPD and REC), split-mouth bleeding score
(SMBS; calculated as the percentage of positive bleeding sites on probing and expressed for
NSPT + Manuka and NSPT-only quadrants, respectively) and split-mouth plaque score
(SMPS; calculated as the percentage of sites with present plaque and expressed for NSPT
+ Manuka and NSPT-only quadrants, respectively) [
14
,
15
]. Third molars, if present, were
excluded from data analysis.
All participants have given written informed consent to study participation.
2.3. Periodontal Treatment
Nonsurgical treatment was performed by standardized protocol by a single operator
(D.O.). All patients received identical oral hygiene instructions, presuming the use of
appropriately sized interdental brushes and manual toothbrushes with regular fluoride-
containing toothpaste. The use of mouthwashes of any formulation was not allowed
during the study period. Mechanical subgingival instrumentation was performed using an
ultrasonic instrument (Piezon, E.M.S. Electro Medical Systems S.A., Nyon, Switzerland)
and curettes (BioGent, Hu-Friedy, Chicago, IL, USA). Local anesthesia (Ubistesin 40 mg/mL
+ 0.005 mg/L, 3M Deutschland GmbH, Seefeld, Germany) was provided to all participants.
Instrumentation was performed according to the individual situation and without any time
limitation. All treatments were concluded within the timeframe of 24 h.
The adjunctive treatment used in this study was a novel commercial product (Pocket
Protect, CleverCool B.V., Lijnden, The Netherlands) containing therapeutic Manuka honey
and hydrogen peroxide. The two substances mix within a double-barrel syringe before
deposition within the pocket.
The product was administered in all pockets (depths
≥
4 mm) in the two active
quadrants as per the instructions of the manufacturer. Once the inserted syringe reached
the bottom of the periodontal pocket, the product was extruded until the excess was
observed in the sulcus. Subjects were not allowed to consume drinks or food for at least
30 min following the procedure.
All subjects were required to report possible adverse effects.
The patients were scheduled for recall visits after three, six, and 12 months when PPD
and CAL were re-evaluated. In the first three months only were the patients scheduled
for supportive treatment at one-month intervals. The supportive treatment consisted of
OH re-instructions, if deemed necessary, and supragingival scaling and polishing. The
collected data were pseudo-anonymized immediately after collection. Only the clinician
performing the treatment had the access to the patient’s identifying information.
2.4. Randomization and Blinding
Randomization of patients was done using a computerized random number generator.
Each quadrant was allocated to receive one of the two treatments (Manuka + NSPT or
NSPT-only), with the allocation ratio forced to 1:1. The concealment was achieved using
sealed and numbered envelopes. A researcher not involved in the operative phases of the
study performed the random allocation sequence and intervention assignment.
Blinding was not possible during the experimental period (operator, subjects) due to
the specific design of the product-delivery syringe and product’s taste.
The examiner was unaware of the treatment allocation at any point during the ongoing
study period. Blinding was also done for statistical analysis.
Materials 2023,16, 1248 4 of 10
2.5. Statistical Analysis
As the assumption of normality of distribution was verified by inspecting normal
Q-Q plots, the comparisons between the NSPT + Manuka and the NSPT-only quadrants
were performed using a two-tailed t-test for independent samples with the assumption
of homoskedasticity. PPD and CAL values were compared between the NSPT + Manuka
and the NSPT-only quadrants at each time point (baseline, three months, six months, and
12 months). The changes in the parameters PPD and CAL (denoted as delta PPD and delta
CAL, respectively) were calculated for each time point by subtracting the baseline values
from the values measured after three months, six months, and 12 months. The obtained
delta values were statistically compared between the NSPT + Manuka and the NSPT-only
quadrants using a two-tailed t-test for independent samples. BoP index and plaque index
were represented as percentages of sites that were positive for bleeding or the presence of
plaque, respectively. These percentages of positive sites were compared between the NSPT
+ Manuka and the NSPT-only quadrants using the chi-square test.
The statistical analysis was performed using SPSS (version 25; IBM, Armonk, NY,
USA) at a level of significance of 0.05.
3. Results
A total of 86 patients were screened for inclusion and 15 participants (eight males and
seven female) were recruited for this pilot study. However, three of them were excluded
from the study due to not showing up at the follow-up appointment at 3 months (two
participants) and 6 months (one participant). Hence, a total of 12 participants (five males
and seven female) were included. The mean age was 43.1 years (range 31–49), with a mean
number of teeth at 26, and 1331 sites with increased PPD (
≥
4 mm); 4–6 mm at 905 sites and
>6 mm at 426 sites. All patients were non-smokers.
Table 1shows the PPD and CAL values, and the corresponding delta values represent-
ing differences from baseline measured after 3, 6, and 12 months. There were no statistically
significant differences in baseline values for PPD and CAL between the sites treated with
NSPT + Manuka and the sites treated with NSPT-only. In addition, no significant differ-
ences were observed for PPD and CAL in the comparisons with the sites treated with NSPT
+ Manuka and the sites treated with NSPT-only at each of the follow-up time periods (3, 6,
and 12 months). However, statistically significant differences between NSPT + Manuka and
NSPT-only were identified in delta PPD values for all follow-up time points, as well as for
delta CAL values for the time points of 3 and 6 months. The delta CAL values calculated for
12 months could be considered marginally significant at the selected level of significance
of 0.05. These statistically significant further improvements due to the adjunctive use of
Manuka amounted to (mm): 0.21, 0.30, and 0.19 for delta CAL and 0.18, 0.28, and 0.16 for
delta PPD values measured after 3, 6, and 12 months, compared to NSPT-only.
Table 2shows FMPS and FMBS values measured at baseline, 3, 6, and 12 months. At
baseline, the quadrants that received NSPT-only had significantly greater values of plaque
and bleeding. No significant differences between the quadrant groups were identified, with
the exception of lower bleeding scores at 6 months in the NSPT + Manuka quadrants.
One patient reported generalized dentine hypersensitivity that spontaneously de-
creased until the 1-month check-up. No other adverse effects were reported.
Materials 2023,16, 1248 5 of 10
Table 1.
Measured values of periodontal pocket depth, clinical attachment level, and changes of these
parameters from the baseline values. All data are represented as mean values with 95% confidence
interval limits in parentheses.
Variable Time Point NSPT + MANUKA NSPT-Only p-Values
PPD (mm) baseline 4.27 (4.12, 4.43) 4.07 (3.93, 4.21) 0.060
3 months 2.81 (2.72, 2.91) 2.82 (2.73, 2.92) 0.846
6 months 2.57 (2.48, 2.65) 2.66 (2.57, 2.74) 0.140
12 months 2.53 (2.45, 2.61) 2.52 (2.44, 2.60) 0.825
∆PPD (mm) 3 months −
1.46 (
−
1.56,
−
1.36)
−
1.25 (
−
1.34,
−
1.15)
0.002
6 months −
1.71 (
−
1.81,
−
1.60)
−
1.41 (
−
1.51,
−
1.31)
<0.001
12 months −
1.74 (
−
1.85,
−
1.63)
−
1.55 (
−
1.66,
−
1.44)
0.016
CAL (mm) baseline 4.30 (4.14, 4.45) 4.11 (3.97, 4.25) 0.080
3 months 2.91 (2.81, 3.02) 2.91 (2.81, 3.01) 0.952
6 months 2.69 (2.60, 2.79) 2.78 (2.68, 2.88) 0.201
12 months 2.66 (2.57, 2.75) 2.63 (2.54, 2.72) 0.609
∆CAL (mm) 3 months −
1.38 (
−
1.49,
−
1.28)
−
1.20 (
−
1.30,
−
1.10)
0.012
6 months −
1.61 (
−
1.72,
−
1.49)
−
1.33 (
−
1.43,
−
1.22)
<0.001
12 months −
1.64 (
−
1.72,
−
1.52)
−
1.48 (
−
1.59,
−
1.37)
0.052
PPD—periodontal pocket depth; CAL—clinical attachment level; ∆—delta.
Table 2.
Measured values of split-mouth bleeding score and split-mouth plaque score, represented as
percentages of positive sites in respective quadrants (%).
Variable Time Point NSPT + MANUKA NSPT-Only p-Values
SMBS (%) baseline 82.1 86.5 0.007
3 months 46.7 43.7 0.178
6 months 44.8 50.8 0.007
12 months 54.6 55.8 0.575
SMPS (%) baseline 92.7 95.4 0.009
3 months 30.9 31.2 0.990
6 months 46.7 47.4 0.775
12 months 51.3 52.2 0.678
SMBS—split-mouth bleeding score (number of positive sites/all measuring sites
×
100 in Manuka or NSPT-only
quadrants); SMPS—split-mouth plaque score (number of positive sites/all measuring sites
×
100 in Manuka or
NSPT-only quadrants); %—percentage.
4. Discussion
This pilot study investigated the impact of Manuka honey as an adjunct to NSPT.
It showed statistically significant improvements in terms of PPD reduction and CAL
gain after 3, 6, and 12 months of follow-up, compared to the outcomes of the NSPT-only.
Improvements in bleeding and plaque scores were also observed in both quadrant groups.
The present study was motivated by numerous literature reports on the beneficial
effects of Manuka honey when used for various medical purposes. Accelerated wound
healing was reported after the topical use of Manuka honey for the treatment of ulcers,
bed sores, and other skin infections [
4
]. In addition, Manuka honey was demonstrated
to promote healing in infected wounds that do not respond to conventional therapy,
i.e., antibiotics and antiseptics, including wounds infected with methicillin-resistant S.
aureus [
16
]. Manuka honey may promote the repair of the damaged intestinal mucosa,
Materials 2023,16, 1248 6 of 10
stimulate the growth of new tissues, and work as an anti-inflammatory agent [
16
]. Clinical
observations have reported reduced symptoms of inflammation when Manuka honey
is applied to wounds [
17
]. The removal of exudate in wounds dressed with honey was
helpful for managing inflamed wounds [
4
]. The aforementioned effects encouraged our
investigation of the possible effects of Manuka honey on periodontitis treatment.
Although the effects of Manuka honey on oral bacteria have not been investigated
in vivo
, there are several
in vitro
studies that convincingly indicated its antibacterial ac-
tivity. The study by Safii et al. was based on the minimum amount of honey required
to kill bacteria or inhibit their growth on blood agar, as evaluated by the minimum bac-
tericidal concentration or minimum inhibitory concentration (MBC/MIC), and showed
a high antibacterial potential of Manuka honey, especially against Gram-negative anaer-
obic bacteria [
18
]. Similar results were published in the
in vitro
work of Schmidlin et al.
on the antimicrobial effect of Manuka honey compared to other types of honey against
three common pathogens present in the oral cavity (S. mutans,P. gingivalis, and A. actino-
mycetemcommitans). Antibacterial activity was analyzed on blood agar, and Manuka honey
demonstrated a stronger antibacterial effect compared to other types of honey due to its
specific non-peroxidase activity mediated by methylglyoxal, to which P. gingivalis was
found to be especially sensitive [17].
The research by Badet and Quero analyzed
in vitro
adhesion of oral cavity bacteria
exposed to different concentrations of Manuka honey on glass and hydroxyapatite surfaces
immersed in saliva. The results showed that Manuka honey with higher methylglyoxal
concentrations inhibits the adhesion of S. mutans [
19
]. Sigrun et al. compared the effec-
tiveness of Manuka honey and regular honey on P. gingivalis, which is one of the most
important periodontal pathogenic bacteria. It was shown that the planktonic form is
extremely sensitive to exposure to Manuka honey, which additionally substantiates its
antibacterial properties [20].
The only
in vivo
study on the use of Manuka honey in the oral cavity is reported in the
article by Al-Khanati et al. who investigated the analgesic effect of Manuka honey applied
to the post-extraction alveolus following the extraction of impacted third molars. Their
randomized split-mouth study showed a statistically significant reduction in postoperative
pain on the side where Manuka honey was applied [
21
]. This finding suggests favorable
analgesic properties and potential anti-inflammatory activity of Manuka honey.
A recent systematic review and meta-analysis analyzed the adjunctive effects of locally
delivered antimicrobials in the nonsurgical treatment of periodontitis. The meta-analysis
for studies of 6–9-month follow-ups showed statistically significant benefits in terms of
PPD reduction (WMD = 0.365) and CAL gain (WMD = 0.263). For long-term studies of
12 to 60 months, significant differences were only observed for PPD (WMD = 0.190). The
authors highlighted that the heterogeneity was significant due to a great number of different
active agents and a difference in study design. The products with the largest observed
benefits were those containing doxycycline or tetracycline [
22
]. The improvements in the
treatment outcome following the adjunctive use of Manuka honey in the present study
can be compared to the systematic review’s results in terms of PPD reduction, as the mean
difference at 6 and 12 months were 0.30 and 0.19, respectively.
Although the differences between the two quadrant groups in our study seem small
and that the baseline values might also seem low, it is interesting to note that in a recent
multicenter clinical trial investigating the flapless application of enamel matrix derivative in
non-surgical therapy when the authors sub-analyzed CAL changes at 12 months including
all pockets, and not only the deep ones, the difference between the control and test group
was only 0.1 mm in favor of the enamel matrix derivative, with overall CAL changes of
0.8 mm and 0.9 mm, respectively. However, when they analyzed only pockets of 5–8 mm,
CAL changes were significantly higher, 2.1 mm for the control group and 2.2 mm for the
test group [
23
]. If we compare the results from the above-mentioned study on all sites to
ours, we can see that our CAL changes in the test quadrants were 1.64 mm and 1.48 mm in
the control quadrants which is higher than in the Schallhorn study.
Materials 2023,16, 1248 7 of 10
Another observation in our study was the continuous improvements in both PPD
reductions and CAL values at 3, 6, and 12 months. However, statistical significance between
the two groups was only found at 6 months in favor of the test quadrants for both variables.
At 3 months, PPD changes were
−
1.46 mm for the test quadrants and
−
1.25 mm coming
very close to statistical significance (p = 0.002) with a further improvement to
−
1.74 mm
in test quadrants and
−
1.55 mm in the control quadrants at 12 months with p values still
not significant. This difference in the lack of significance at 3 and 12 months compared to 6
months, although the actual numbers in differences are 0.21 mm, 0.30 mm, and 0.19 mm,
could be due to the pressure during probing which cannot be entirely controlled although
clinical measurements were done by an experienced and calibrated periodontist.
Both quadrant groups presented with an initial reduction in plaque and bleeding
scores following treatment. After 3 months, at re-evaluation, the reduction of bleeding
was 35.4% in the Manuka + NSPT and 42.8% in NSPT-only quadrants. These values are
lower than previously reported by the systematic review of Suvan et al., of a weighted
mean reduction of 56.7% at 3/4 months after non-surgical treatment [
3
]. At 6 months,
while the Manuka + NSPT quadrants presented a further, albeit minimal, reduction of 1.9%
in bleeding scores, the NSPT-only quadrants presented a rise in bleeding scores of 7.1%.
From 6 to 12 months, quadrants treated with both treatment modalities presented with
an increase in bleeding scores. The observed reduction of plaque (SMPS) at 3 months was
61.8% in the Manuka + NSPT quadrants and 64.2% in the NSPT-only quadrants, which is as
expected following nonsurgical treatment [
24
]. At 6 and 12 months, quadrants treated with
both modalities expressed an increase in plaque score. The increase in both parameters
at later follow-ups could be explained by the omission of intensive supportive treatment
at 1-month intervals and lack of patients’ motivation. It needs to be highlighted that the
data on the effects of these two treatment modalities and the direct comparison between
the two treatments on plaque and bleeding have to be interpreted with caution, as there
was a statistically significant difference in these parameters between the Manuka + NSPT
and NSPT-only quadrants at baseline. As per the effects of Manuka honey on plaque and
bleeding, a pilot study by Molan et al. showed that Manuka honey has a positive effect
on reducing the amount of dental plaque and the incidence of gingivitis compared to the
control group that did not use Manuka honey [7].
The commercial product used in this research combines Manuka honey and hydrogen
peroxide. Thus, the effect of the adjunctive cannot be attributed solely to Manuka. The
extent of these substances’ sole or combined impact on clinical outcomes would need to be
evaluated in an appropriately designed RCT. Schmidlin et al., however, reported a greater
antibacterial effect of Manuka above the NPA value of 15 compared to “regular” honey,
whose activity relies on peroxide-based antimicrobial factors [
17
]. Hydrogen peroxide as an
adjunct to non-surgical treatment for pocket irrigation failed to show further improvements
in clinical outcomes when compared to subgingival debridement alone [
24
]. Research on
the use of 1.7% hydrogen peroxide in custom trays and H
2
O
2
photolysis (irradiation of 3%
H
2
O
2
with 405 nm light or diode laser) showed promising results in terms of significantly
greater PPD reduction in test groups compared to controls [25–28].
Adding hydrogen peroxide in the commercial product definitely facilitates clinical
handling as it decreases the honey’s viscosity and the application inside the periodontal
pockets.
The main limitation of this pilot study is the small sample size (n = 12). However,
despite the small sample size, the included subjects represent a specific population of
patients with severe inflammation and advanced forms of periodontitis, for which it was
possible to identify a small but statistically significant improvement in the reduction of
PPD at sites treated with Manuka honey compared to the control sites. An analogous
improvement was identified for CAL in the sites treated with Manuka honey.
Furthermore, microbiological analysis was not conducted in this research. So far,
antibacterial efficacy of Manuka on periodontal pathogens was shown only in
in vitro
studies [
17
,
18
]. Thus, further data is needed from studies on humans. Studies with mid-
Materials 2023,16, 1248 8 of 10
and long-term follow-ups may show possible prolonged effects of this adjunctive on the
subgingival microbial composition compared to subgingival debridement alone.
The statistical analysis was performed at the level of individual periodontal sites,
meaning that the statistical unit was represented by the site instead of the patient. When
individual sites are considered as statistical units, the actual sample size becomes 2025
(12 subjects
×
28.125 teeth per subject on average
×
6 sites per tooth = 2025 sites in total).
Calculating the “delta” values for PPD and CAL and using these values instead of the
original pooled PPD and CAL values measured at each individual time point provided
higher statistical power for identifying significant differences in the comparisons of the
NSPT + Manuka and the NSPT-only quadrants. By calculating the differences in PPD
and CAL at the level of the individual site, the heterogeneity among sites becomes less
influential, as the “net” effect is isolated for each site and used for the statistical analysis
rather than pooling the original PPD and CAL values measured at individual time points.
This reasoning explains why the significant effects of Manuka honey were identified only
for delta PPD and delta CAL variables and not for the original PPD and CAL variables.
Furthermore, the authors are aware of the possible disadvantages of the split-mouth design.
As both sides received some modality of treatment and the product itself comes in a highly
viscous form and is delivered locally, the possibility of the carry-across effect (i.e., bacterial
contamination from an untreated sides/possible effect of the Manuka honey on the NSPT-
only quadrants) was minimized [
29
,
30
]; however, we do recognize a risk of it happening.
A relatively high number of teeth (20 teeth) set as an inclusion criterion also positively
influenced the similarity between randomization units.
5. Conclusions
This pilot study indicated a promising potential of Manuka honey as an adjunct
in NSPT. Despite the improvement in outcomes appearing modest in absolute terms, it
was statistically significant for all follow-up time points, indicating the potential use of
Manuka honey as a simple and affordable adjunct to non-surgical periodontal therapy.
Furthermore, the product is considered a safe adjunct and no adverse events related to its
use were reported during the study period. Encouraging results from this pilot study led
to a further randomized clinical study on a larger sample that is currently being performed
by our group.
Author Contributions:
D.B.—study conception, experimental design, funding acquisition, per-
formed experiments, formal analysis and data interpretation, statistical analysis, visualization, and
wrote manuscript; D.O., L.M., A.B., and A.Š.—experimental design, performed experiments, data
acquisition and interpretation, and revised and approved final manuscript; D.B.—study conception,
experimental design, supervision, data interpretation, project administration, resources, and revised
and approved final manuscript. D.B.—experimental design, data acquisition and interpretation, su-
pervision, resources, and revised and approved final manuscript. D.O. and L.M.—study conception,
experimental design, supervision, data interpretation, project administration, resources, and revised
and approved final manuscript. D.B.—study conception, supervision, resources, data interpretation,
project administration, and revised and approved final manuscript. All authors have read and agreed
to the published version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement:
The study was conducted in accordance with the Declaration
of Helsinki, and approved by the Ethics Committee of the School of Dental Medicine, University of
Zagreb, Croatia; approval No. 05-PA-30-IX-9/2019.
Informed Consent Statement:
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement: Not applicable.
Conflicts of Interest: The authors declare no conflict of interest.
Materials 2023,16, 1248 9 of 10
References
1.
Chapple, I.L.C.; Mealey, B.L.; Van Dyke, T.E.; Bartold, P.M.; Dommisch, H.; Eickholz, P.; Geisinger, M.L.; Genco, R.J.; Glogauer,
M.; Goldstein, M.; et al. Periodontal Health and Gingival Diseases and Conditions on an Intact and a Reduced Periodontium:
Consensus Report of Workgroup 1 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases
and Conditions. J. Periodontol. 2018,89, S74–S84. [CrossRef]
2.
Sanz, M.; Herrera, D.; Kebschull, M.; Chapple, I.; Jepsen, S.; Berglundh, T.; Sculean, A.; Tonetti, M.S.; EFP Workshop Participants
and Methodological Consultants. Treatment of Stage I–III Periodontitis—The EFP S3 Level Clinical Practice Guideline. J. Clin.
Periodontol. 2020,47, 4–60. [CrossRef] [PubMed]
3.
Suvan, J.; Leira, Y.; Moreno Sancho, F.M.; Graziani, F.; Derks, J.; Tomasi, C. Subgingival Instrumentation for Treatment of
Periodontitis. A Systematic Review. J. Clin. Periodontol. 2020,47, 155–175. [CrossRef] [PubMed]
4.
Carter, D.A.; Blair, S.E.; Cokcetin, N.N.; Bouzo, D.; Brooks, P.; Schothauer, R.; Harry, E.J. Therapeutic Manuka Honey: No Longer
So Alternative. Front. Microbiol. 2016,7, 569. [CrossRef] [PubMed]
5.
Maddocks, S.E.; Jenkins, R.E. Honey: A Sweet Solution to the Growing Problem of Antimicrobial Resistance? Future Microbiol.
2013,8, 1419–1429. [CrossRef] [PubMed]
6.
Mandal, M.D.; Mandal, S. Honey: Its Medicinal Property and Antibacterial Activity. Asian Pac. J. Trop. Biomed.
2011
,1, 154–160.
[CrossRef] [PubMed]
7.
Adams, C.J.; Manley-Harris, M.; Molan, P.C. The Origin of Methylglyoxal in New Zealand Manuka (Leptospermum Scoparium)
Honey. Carbohydr. Res. 2009,344, 1050–1053. [CrossRef]
8.
Norton, A.M.; McKenzie, L.N.; Brooks, P.R.; Pappalardo, L.J. Quantitation of Dihydroxyacetone in Australian Leptospermum
Nectar via High-Performance Liquid Chromatography. J. Agric. Food Chem. 2015,63, 6513–6517. [CrossRef]
9.
Alvarez-Suarez, J.; Gasparrini, M.; Forbes-Hernández, T.; Mazzoni, L.; Giampieri, F. The Composition and Biological Activity of
Honey: A Focus on Manuka Honey. Foods 2014,3, 420–432. [CrossRef]
10. Tashkandi, H. Honey in Wound Healing: An Updated Review. Open Life Sci. 2021,16, 1091–1100. [CrossRef]
11.
Minden-Birkenmaier, B.; Bowlin, G. Honey-Based Templates in Wound Healing and Tissue Engineering. Bioengineering
2018
,5,
46. [CrossRef] [PubMed]
12.
Armitage, G.C. Development of a Classification System for Periodontal Diseases and Conditions. Ann. Periodontol.
1999
,4, 1–6.
[CrossRef] [PubMed]
13.
Tonetti, M.S.; Greenwell, H.; Kornman, K.S. Staging and Grading of Periodontitis: Framework and Proposal of a New Classification
and Case Definition. J. Clin. Periodontol. 2018,45, S149–S161. [CrossRef] [PubMed]
14. Ainamo, J.; Bay, I. Problems and Proposals for Recording Gingivitis and Plaque. Int. Dent. J. 1975,25, 229–235.
15. O’Leary, T.J.; Drake, R.B.; Naylor, J.E. The Plaque Control Record. J. Periodontol. 1972,43, 38. [CrossRef] [PubMed]
16.
Niaz, K.; Maqbool, F.; Bahadar, H.; Abdollahi, M. Health Benefits of Manuka Honey as an Essential Constituent for Tissue
Regeneration. Curr. Drug Metab. 2017,18, 881–892. [CrossRef] [PubMed]
17.
Schmidlin, P.R.; English, H.; Duncan, W.; Belibasakis, G.N.; Thurnheer, T. Antibacterial Potential of Manuka Honey against Three
Oral Bacteria in Vitro. Swiss Dent. J. 2014,124, 922–924.
18.
Safii, S.H.; Tompkins, G.R.; Duncan, W.J. Periodontal Application of Manuka Honey: Antimicrobial and Demineralising Effects In
Vitro. Int. J. Dent. 2017,2017, 9874535. [CrossRef]
19.
Badet, C.; Quero, F. The in Vitro Effect of Manuka Honeys on Growth and Adherence of Oral Bacteria. Anaerobe
2011
,17, 19–22.
[CrossRef]
20.
Eick, S.; Schäfer, G.; Kwieci´nski, J.; Atrott, J.; Henle, T.; Pfister, W. Hone—A Potential Agent against Porphyromonas Gingivalis:
An in Vitro Study. BMC Oral Health 2014,14, 24. [CrossRef]
21.
Al-Khanati, N.M.; Al-Moudallal, Y. Effect of Intrasocket Application of Manuka Honey on Postsurgical Pain of Impacted
Mandibular Third Molars Surgery: Split-Mouth Randomized Controlled Trial. J. Maxillofac. Oral Surg.
2019
,18, 147–152.
[CrossRef]
22.
Herrera, D.; Matesanz, P.; Martín, C.; Oud, V.; Feres, M.; Teughels, W. Adjunctive Effect of Locally Delivered Antimicrobials in
Periodontitis Therapy: A Systematic Review and Meta-analysis. J. Clin. Periodontol. 2020,47, 239–256. [CrossRef] [PubMed]
23.
Schallhorn, R.A.; McClain, P.K.; Benhamou, V.; Doobrow, J.H.; Grandin, H.M.; Kasaj, A. Application of Enamel Matrix Derivative
in Conjunction with Non-surgical Therapy for Treatment of Moderate to Severe Periodontitis: A 12-month, Randomized
Prospective, Multicenter Study. J. Periodontol. 2021,92, 619–628. [CrossRef]
24.
Wennstrom, J.L.; Tomasi, C.; Bertelle, A.; Dellasega, E. Full-Mouth Ultrasonic Debridement versus Quadrant Scaling and Root
Planing as an Initial Approach in the Treatment of Chronic Periodontitis. J. Clin. Periodontol.
2005
,32, 851–859. [CrossRef]
[PubMed]
25.
Putt, M.S.; Mallatt, M.E.; Messmann, L.L.; Proskin, H.M. A 6-Month Clinical Investigation of Custom Tray Application of Peroxide
Gel with or without Doxycycline as Adjuncts to Scaling and Root Planing for Treatment of Periodontitis. Am. J. Dent.
2014
,27,
273–284. [PubMed]
26.
Putt, M.S.; Proskin, H.M. Custom Tray Application of Peroxide Gel as an Adjunct to Scaling and Root Planing in the Treatment of
Periodontitis: Results of a Randomized Controlled Trial after Six Months. J. Clin. Dent. 2013,24, 100–107. [PubMed]
Materials 2023,16, 1248 10 of 10
27.
Kanno, T.; Nakamura, K.; Ishiyama, K.; Yamada, Y.; Shirato, M.; Niwano, Y.; Kayaba, C.; Ikeda, K.; Takagi, A.; Yamaguchi, T.; et al.
Adjunctive Antimicrobial Chemotherapy Based on Hydrogen Peroxide Photolysis for Non-Surgical Treatment of Moderate to
Severe Periodontitis: A Randomized Controlled Trial. Sci. Rep. 2017,7, 12247. [CrossRef] [PubMed]
28.
Nammour, S.; El Mobadder, M.; Maalouf, E.; Namour, M.; Namour, A.; Rey, G.; Matamba, P.; Matys, J.; Zeinoun, T.; Grzech-
Le´sniak, K. Clinical Evaluation of Diode (980 Nm) Laser-Assisted Nonsurgical Periodontal Pocket Therapy: A Randomized
Comparative Clinical Trial and Bacteriological Study. Photobiomodulation Photomed. Laser Surg. 2021,39, 10–22. [CrossRef]
29.
Hujoel, P.P.; DeRouen, T.A. A Survey of Endpoint Characteristics in Periodontal Clinical Trials Published 1988-1992, and
Implications for Future Studies. J. Clin. Periodontol. 1995,22, 397–407. [CrossRef]
30.
Lesaffre, E.; Philstrom, B.; Needleman, I.; Worthington, H. The Design and Analysis of Split-Mouth Studies: What Statisticians
and Clinicians Should Know: THE SPLIT-MOUTH DESIGN. Statist. Med. 2009,28, 3470–3482. [CrossRef]
Disclaimer/Publisher’s Note:
The statements, opinions and data contained in all publications are solely those of the individual
author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to
people or property resulting from any ideas, methods, instructions or products referred to in the content.