Open Access
CC BY 4.0 · Eur J Dent 2023; 17(04): 974-999
DOI: 10.1055/s-0042-1757582
Review Article

Impact of Dentine Pretreatment with Matrix Metalloproteinase Inhibitors on Bond Strength of Coronal Composite Restorations: A Systematic Review and Meta-analysis of In Vitro Studies

Hasan Jamal
1   Paediatric Dentistry Department, Eastman Dental Institute, University College London, London, United Kingdom
2   Department of Biomaterials and Tissue Engineering, Royal Free Hospital, UCL Eastman Dental Institute, London, United Kingdom
,
Rayan Yaghmoor
2   Department of Biomaterials and Tissue Engineering, Royal Free Hospital, UCL Eastman Dental Institute, London, United Kingdom
3   Department of Microbial Diseases, UCL Eastman Dental Institute, Royal Free Hospital, London, United Kingdom
4   Department of Restorative Dentistry, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia
,
Hassan Abed
5   Department of Basic and Clinical Oral Sciences, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia
,
Anne Young
2   Department of Biomaterials and Tissue Engineering, Royal Free Hospital, UCL Eastman Dental Institute, London, United Kingdom
,
Paul Ashley
1   Paediatric Dentistry Department, Eastman Dental Institute, University College London, London, United Kingdom
› Institutsangaben

Funding The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code: (22UQU4350291DSR06).
 

Abstract

Matrix metalloproteinase (MMP) enzymes participate in collagen matrix degradation, including in dentine, potentially compromising bond strength. Therefore, MMP inhibitors have been hypothesized to improve restoration bond strength and stability. This systematic review aimed to evaluate the influence of different MMP inhibitors applied as dentine surface pretreatments on the immediate (24 hours) and longer term (months) bond strength of direct coronal composite restorations. This systematic literature review followed the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) statement. A systematic literature search of three databases (Ovid MEDLINE, Ovid Embase, and Google Scholar) was conducted independently by two reviewers from inception to April 2022. An adapted quality assessment tool was independently applied by two reviewers for risk of bias assessment. RevMan v5.4 software was used for meta-analyses. A randomeffectsmodel was used to generatemean differences with 95% confidence intervals for treatment and control comparisons. The Q-test and I2-test were used to test for heterogeneity. The proportion of total variance across studies attributable to heterogeneity rather than chance was calculated. Overall effects were tested using the Z-test, while subgroup differences were tested using Chi-squared tests. Of 934 studies, 64 studies were included in the systematic review and 42 in the meta-analysis. Thirty-one MMP inhibitors were reported, three of which were included in the meta-analysis: 2% chlorhexidine (CHX), 0.3M carbodiimide (EDC), and 0.1% riboflavin (RIBO). Pretreatment with 2% CHX for 30 and 60 seconds did not significantly improve bond strength compared with controls either immediately or after long-termageing. However, pretreatment with 0.3MEDC and 0.1% RIBO (but not CHX) significantly improved bond strength compared with control groups both immediately and over time. Most studies showed a medium risk of bias. These in vitro findings pave the way for rationale clinical trialing of dentine surface pretreatment with MMP inhibitors to improve clinical outcomes.


Introduction

Since their introduction around six decades ago, restorative adhesives have undergone numerous improvements.[1] [2] Despite these advances, adhesive restorations often lose their bond strength over time, leading to their failure.[3] [4] Adhesive restorations critically rely on their bond with the tooth structures for strength, with the interface—the hybrid layer—crucial in determining the bond's longevity and stability.[5] [6] The collagen fibrils in dentine (mainly type 1 collagen) are key to establishing a strong bond, and their deterioration is thought to be the main reason underlying bond failure to dentine.[7]

Recent studies have examined the role of endogenous enzymes present within the dentine extracellular matrix (ECM) and their effect on bond stability. Among these enzymes, matrix metalloproteinases (MMPs) represent a group of calcium- and zinc-dependent host-derived enzymes.[8] MMPs are divided into six subgroups: collagenases (MMP-1 and MMP-8), stromelysins (MMP-3, MMP-10, MMP-11, and MMP-20), gelatinases or type-IV collagenases (MMP-2 and MMP-9), matrilysin (MMP-7), metalloelastase (MMP-12), and membrane-type metalloproteinases (MMP-14, MMP-15, MMP-16, and MMP-17).[9] Of these, four MMPs have been identified within the dentine extracellular matrix: MMPs-2, -8, -9, and -20, with MMP-2 and -9 as the most abundant.[10] [11] These enzymes are secreted by odontoblasts during odontogenesis and remain silenced and inactive within the dentine ECM.[12] However, these MMPs are activated either by biological acids produced by cariogenic bacteria[13] or acids introduced during acid etching.[14] [15] When activated, they start to degrade the exposed collagen fibrils within the dentine.[16] Therefore, inhibiting MMPs could help to preserve the hybrid layer and, therefore, bond stability.

Several types of MMP inhibitor (synthetic and natural) have been described including benzalkonium chloride,[17] [18] chlorhexidine,[18] [19] [20] [21] galardin,[22] green tea extract,[23] [24] and zinc.[25] MMP inhibitors can be administered either as dentine surface pretreatments or those incorporated into the adhesive. The current systematic review and meta-analysis aimed to collect and analyze the available in vitro evidence on the influence of different MMP inhibitors applied as dentine surface pretreatments on the immediate and long-term bonding strength of coronal composite restorations. The null hypothesis was that there would be no difference in bond strength after MMP inhibitor use compared with controls.


Methods

Eligibility Criteria

The systematic review was developed according to the PICO scheme ([Table 1])[26] and was conducted according to the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) guidelines[27]:

Table 1

Keywords and the strategy used in MEDLINE and Embase

Medline (Ovid)

Embase

P

1. Extracted human teeth.mp./OR Human teeth.mp.

2. Sound dentine.mp./OR healthy dentine.mp.

3. Carious affected dentine.mp./OR Caries affected dentine.mp./OR affected dentine.mp.

4. Dentine$.mp.

5. 1 OR 2 OR 3 OR 4

1. Extracted human teeth.mp./OR Human teeth.mp.

2. Sound dentine.mp./OR healthy dentine.mp.

3. Carious affected dentine.mp./OR Caries affected dentine.mp./OR affected dentine.mp.

4. Dentine$.mp.

5. 1 OR 2 OR 3 OR 4

I

6. Matrix metalloproteinase inhibitors/OR MMP inhibitors.mp.

6. Matrix metalloproteinase inhibitors/OR MMP inhibitors.mp.

C

7. No matrix metalloproteinase inhibitors/OR No MMP inhibitors

7. No matrix metalloproteinase inhibitors/OR No MMP inhibitors

O

8. Bond strength/OR Bond stability

8. Bond strength/OR Bond stability

Combined

1 OR 2 OR 3 OR 4 AND 6 AND 7 AND 8)

1 OR 2 OR 3 OR 4 AND 6 AND 7 AND 8)

Abbreviation: MMP, matrix metalloproteinase.


Population: all studies examining extracted human teeth, caries-free dentine, healthy dentine, sound dentine, carious-affected dentine, or affected dentin.

Interventions: all studies examining MMP inhibitors as dentine surface pretreatments prior to direct coronal composite restoration placement. Therefore, studies that used luting cements and glass ionomer cements were excluded.

Comparator(s)/control(s): teeth without intervention (i.e., without the addition of MMP inhibitor). Studies that included no comparator were excluded.

Outcome: the main outcome was bond strength or bond stability at the microscale (by microtensile and microshear testing). Studies that tested bond strength at the macroscale were excluded. Included studies needed to have aged the samples for at least 24 hours in water or artificial saliva. Thus, studies with ageing up to 24 hours only and/or studies that used ageing solutions other than water or artificial saliva were excluded.


Search Strategy

Types of Searched Studies

The search included published, peer-reviewed in vitro studies presenting the results (means and standard deviations [SDs]) quantitively and numerically in the English language. Thus, studies that reported the results in graphs or figures only were excluded. Non–peer reviewed studies, conference posters, letters, theses, reviews, and editorials were excluded.


Period of Reviews (Timing) and Databases

A systematic literature search was conducted in three databases: Ovid MEDLINE (1946–April 2022), Embase (1974–April 2022; see [Table 1]), and Google Scholar (up to April 2022).

With respect to the search strategy for Google Scholar, the following terms were used: “Extracted human teeth” OR “human teeth” OR “Sound dentine” OR “healthy dentine” OR “affected dentine” OR “Carious affected dentine” OR “Caries affected dentine” OR “Dentine” AND “Matrix metalloproteinase inhibitors” OR “MMP inhibitors” AND “Bond strength” OR “Bond stability.”



Data Selection and Collection Processes

Full texts of all eligible studies were uploaded to reference management software (EndNote X9.3.1) and duplicate publications were removed automatically. Two authors (H.J. and R.Y.) screened the titles and abstracts, and the full text of studies meeting the inclusion criteria was read. Two evaluators (H.J. and R.Y.) independently screened each full-text paper based on the eligibility criteria. In case of discrepancies about study eligibility between the two reviewers, a further evaluator was involved (H.A. or P.A.). A data extraction form included the following: authors' names, year of publication, type of MMP inhibitor used, duration of MMP inhibitor used as dentine pretreatment, substrate condition, type of bonding agent, type of ageing solution, period of ageing, type of bond strength test, and bond strength means. Two reviewers (H.J. and R.Y.) were independently involved in data collection. An experienced third reviewer (P.A.) independently extracted data from 10% of studies to check process consistency. Conflicts of opinion were resolved through consensus by consulting a further reviewer (H.A. or A.Y.).


Risks of Bias and Quality Assessment

A quality assessment tool adapted from a previous study[28] was independently used by two reviewers (H.J. and R.Y.). The tool evaluated bias in terms of sample randomization, substrate condition, duration of dentine pretreatment, the use of materials according to the manufacturer's instructions, storage medium, interface surface area, restorative and bond tests performed by a single operator, sample size calculation (power analysis), and blinding of the operator during bond strength testing. Minor modifications were added to the risk of bias evaluation tool, which are “dentine pretreatment duration” and “storage medium”. For each component of the tool, the letter “Y (yes)” was assigned if the author reported the item and “N (no)” if it was not reported. The grading judgement of “low,” “medium,” or “high” for the study was based on the total number of “Ys” as follows: one to five (high), six, or seven (medium), and eight or nine (low).


Data Synthesis

Findings were summarized narratively using text and tables. For example, findings were summarized according to type of MMP inhibitor used, duration of dentine pretreatment, substrate condition (caries-free or caries-affected), type/mode of bonding agent, type of ageing solution, period of ageing, type of bond strength test, and mean bond strength.


Meta-analysis

Review Manager (RevMan) version 5.4 software from the Cochrane Collaboration was used for meta-analyses using the following information: the average difference in outcome measures between the intervention and control groups, the number of teeth in each treatment group, and the standard deviations. These data were categorized into three time periods: 24 hours, 6 months, and 12 months, where applicable, and further divided into the type of MMP inhibitor, the adhesive application method used (self-etching or etch and rinse), and the pretreatment duration. Only MMP inhibitors applied for 30 and 60 seconds were included as they contained enough data for the meta-analysis.

The mean differences (MDs) and their 95% confidence intervals (CIs) were calculated. Findings from all comparisons were generally pooled according to the three time periods (24 hours, 6 months, and 12 months). After establishing the pooled MDs according to time, additional pooling was carried out depending on the various parameters indicated. A positive MD supports the experimental group, whereas a negative MD favors the control group. A random-effects model was used to generate MDs with 95% CIs for treatment and control comparisons.

The Q-test and I2 -test were used to test for heterogeneity. The I2 statistics was interpreted according to the Cochrane guidelines, with 0 to 29% as being low, 30 to 50% as moderate, and 50 to 90% as considerable heterogeneity.[29] The proportion of total variance across studies attributable to heterogeneity rather than chance was calculated. Finally, the overall effects were tested using the Z-test, while subgroup differences were tested using Chi-squared tests.

The following analyses were carried out:

  1. 2% chlorhexidine (CHX) versus control at baseline (24 hours).

  2. 2% CHX versus control at 6 months.

  3. 2% CHX versus control at 12 months.

  4. 0.3 M 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) versus control at baseline.

  5. 0.3 M EDC versus control at 12 months.

  6. 0.1% riboflavin (RIBO) versus control at baseline.

  7. 0.1% RIBO versus control at 6 months.

  8. 2% CHX versus control at baseline (according to pretreatment duration of 30 seconds).

  9. 2% CHX versus control at 6 months (according to pretreatment duration of 30 seconds).

  10. 2% CHX versus control at baseline (according to pretreatment duration of 60 seconds).

  11. 2% CHX versus control at 6 months (according to pretreatment duration of 60 seconds).



Results

Study Selection

A flowchart summarizing the selection process according to the PRISMA statement is shown in [Fig. 1].[27] During the initial search, 934 potentially eligible studies were retrieved. After removal of duplicates, 763 studies remained of which 193 remained after reviewing the titles and 163 after reviewing the abstracts. Following reading the full texts, 64 studies were included in the study and 42 were included in the meta-analysis.

Zoom
Fig. 1 PRISMA 2020 flowchart diagram of study selection.[27] PRISMA, Preferred Reporting Items for Systematic Review and Meta-analyses.

Study Characteristics

The data obtained from the included publications are listed in [Table 2]. The 64 included in vitro studies were published between 2009 and 2022.

Table 2

Characteristics of the included studies

Study/year

MMP inhibitor type

Pretreatment duration (s)

Substrate condition

Adhesive system (mode of application)

Ageing solution

Period of ageing

Groups

Bond strength means (SD)

Baena et al/2020[30]

CS

60

Caries-free

Optibond FL (Kerr; etch-and-rinse; OFL)

Scotchbond Universal (3M; self-etch; SBU)

Artificial saliva

24 hours

CS 0.1% + OFL

Control (OFL)

CS 0.1% + SBU

Control (SBU)

38.0 (7.7)

41.3 (14.5)

28.1 (14.3)

25.0 (16.5)

10,000 thermocycles

CS 0.1% + OFL

Control (OFL)

CS 0.1% + SBU

Control (SBU)

29.2 (14.1)

32.2 (12.9)

33.1 (17.0)

30.4 (11.8)

Balloni et al/2017[31]

CHX

60

Caries-free

Clearfil SE bond (self-etch)

Water

24 hours

CHX 2%

Control

19.24 (11.89)

12.67 (7.43)

6 months

CHX 2%

Control

11.97 (9.95)

10.22 (5.00)

Bravo et al/2017[32]

CHX

20

Caries-free

Adper Scotchbond 1XT (etch-and-rinse; ASB)

Adper prompt (self-etch; AP)

Single Bond Universal (self-etch; SBU)

Water

3 days

CHX 2% + ASB

Control (ASB)

CHX 2% + AP

Control (AP)

CHX 2% + SBU

Control (SBU)

26.28 (9.29)

28.56 (5.83)

24.21 (7.52)

20.14 (4.87)

28.43 (9.78)

29.24 (7.90)

3 months

CHX 2% + ASB

Control (ASB)

CHX 2% + AP

Control (AP)

CHX 2% + SBU

Control (SBU)

32.26 (10.33)

19.82 (7.65)

28.51 (13.18)

20.86 (6.13)

44.11 (12.09)

23.54 (12.09)

6 months

CHX 2% + ASB

Control (ASB)

CHX 2% + AP

Control (AP)

CHX 2% + (SBU)

Control (SBU)

31.73 (5.18)

23.39 (5.69)

27.37 (4.40)

20.51 (5.66)

36.88 (6.65)

23.62 (7.07)

de Faria Teixeira et al/2015[33]

CHX

60

Not mentioned

Clearfil SE bond (self-etch)

Water

24 hours

CHX 2%

Control

28.0 (8.4)

24.2 (7.2)

6 months

CHX 2%

Control

33.4 (9.3)

21.8 (7.3)

Comba et al/2020[34]

DCC

60

Caries-free

Scotch bond universal (SBU) (self-etch) and etch and rinse

Artificial saliva

24 hours

0.5M DCC SBU (ER)

Control SBU (ER)

0.5M DCC SBU (SE)

Control SBU (SE)

46.0 (5.3)

37.1 (12.5)

39.4 (11.1)

26.3 (11.4)

12 months

0.5M DCC SBU (ER)

Control SBU (ER)

0.5M DCC SBU (SE)

Control SBU (SE)

33.5 (13.9)

31.0 (11.0)

35.3 (13.9)

13.4 (9.1)

Czech et al/2019[24]

CHX

EGCG

60

Caries-affected

Adper Single Bond 2 (etch and rinse)

Water

24 hours

EGCG 200 μg/mL

CHX 2%

Control

24.08 (7.20)

14.64 (7.74)

23.43 (7.73)

6 months

EGCG 200 μg/mL

CHX 2%

Control

18.67 (8.51)

11.20 (4.79)

16.28 (9.58)

12 months

EGCG 200 μg/mL

CHX 2%

Control

16.77 (5.50)

10.17 (3.02)

14.91 (6.92)

Dávila-Sánchez et al/2020[35]

QUE

HES

RUT

NAR

PAC

60

Caries-affected

Scotchbond Universal (3M; etch and rinse)

Water

24 hours

HES 6.5%

PAC 6.5%

QUE 6.5%

NAR 6.5%

RUT 6.5%

Control

18.41 (5.30)

20.66 (3.92)

24.58 (4.90)

24.64 (3.70)

26.00 (5.51)

14.42 (4.43)

25,000 thermocycles

HES 6.5%

PAC 6.5%

QUE 6.5%

NAR 6.5%

RUT 6.5%

Control

15.73 (6.07)

17.20 (2.72)

12.02 (5.21)

22.12 (2.92)

21.08 (4.75)

9.43 (4.29)

Costa et al/2019[36]

CHX

EGCG

60

Eroded (ERO) and non-eroded (non-ERO)

Clearfil SE bond (self-etch)

Water

24 hours

CHX 2% (non-ERO)

CHX 2% (ERO)

EGCG 0.1% (non-ERO)

EGCG 0.1% (ERO)

Control (non-ERO)

Control (ERO)

40.87 (10.23)

49.30 (9.42)

53.67 (6.10)

61.61 (3.17)

52.44 (8.47)

59.25 (5.91)

6 months

CHX 2% (non-ERO)

CHX 2% (ERO)

EGCG 0.1% (non-ERO)

EGCG 0.1% (ERO)

Control (non-ERO)

Control (ERO)

32.77 (10.67)

36.91 (9.88)

50.02 (3.42)

44.63 (13.26)

47.64 (11.67)

45.16 (11.87)

El Baz and Aboulenien/2018[37]

EGCG

60

Caries-free

Primer and Bond one (Dentsply; etch and rinse)

Water

24 hours

EGCG 0.1%

Control

18.8 (0.2)

15.4 (0.7)

6 months

EGCG 0.1%

Control

17.6 (0.3)

12.2 (0.9)

5,000 thermocycles

EGCG 0.1%

Control

22.1 (0.7)

8.8 (0.8)

Fang et al/2017[38]

MAP

GM6001

60

Caries-free

Gluma Comfort Bond (etch and rinse)

Water

24 hours

MAP 1 mg/mL

GM6001 10μM

Control

19.31 (4.48)

18.86 (4.2)

19.25 (4.21)

2,500 thermocycles

MAP 1 mg/mL

GM6001 10μM

Control

12.22 (4.49)

10.87 (4.27)

6.08 (3.12)

Fernandes et al/2021[39]

CHX

EGCG

60

Caries-free

Clearfil SE Bond Primer (self-etch)

Artificial saliva

24 hours

CHX 2%

EGCG 0.01%

Control

44.16 (6.81)

42.76 (7.36)

40.65 (6.51)

12 months

CHX 2%

EGCG 0.01%

Control

33.58 (10.49)

34.91 (7.84)

33.85 (9.27)

Fialho et al/2019[40]

CHX

EGCG

60

Caries-affected

Adper Single Bond 2 (3M; etch and rinse)

Water

24 hours

EGCG 0.2%

EGCG 2%

EGCG 0.5%

CHX 2%

Control

32.65 (9.97)

29.16 (11.52)

28.57 (6.30)

33.33 (11.26)

35.81 (8.25)

12 months

EGCG 0.2%

EGCG 2%

EGCG 0.5%

CHX 2%

Control

22.75 (9.38)

17.15 (10.61)

23.65 (7.19)

19.98 (7.01)

26.17 (12.28)

Gerhardt et al/2016[41]

CHX

EGCG

GT

60

Caries-free

Clearfil SE Bond (self-etch)

Water

24 hours

CHX 2%

EGCG 2%

GT 2%

Control

13.31 (3.36)

6.93 (3.43)

10.60 (4.69)

8.64 (5.52)

6 months

CHX 2%

EGCG 2%

GT 2%

Control

11.09 (4.98)

15.96 (5.32)

17.82 (12.20)

16.69 (7.20)

Campos et al/2019[42]

CHX

Not mentioned

Caries-affected

Clearfil SE Bond (self-etch)

Water

24 hours

CHX 2%

Control

19.84 (8.11)

24.89 (9.44)

12 months

CHX 2%

Control

17.59 (8.85)

28.30 (11.54)

Giacomini et al/2020[43]

CHX

30

Caries-free

Adper Single Bond 2 (etch and rinse)

Adper Single Bond Universal (etch and rinse)

Adper Single Bond Universal self-etch (self-etch)

Artificial saliva

24 hours

CHX 2% (ASB)

Control

CHX 2% (ASU-ER)

Control

CHX 2% (ASU-SE)

Control

28.41 (7.64)

33.35 (9.01)

33.66 (7.79)

31.62 (8.20)

37.47 (10.68)

45.62 (12.39)

6 months

CHX 2% (ASB)

Control

CHX 2% (ASU-ER)

Control

CHX 2% (ASU-SE)

Control

31.55 (6.15)

32.59 (9.44)

33.79 (6.24)

32.05 (7.04)

34.25 (11.21)

40.15 (14.77)

Grandizoli and Pinheiro/2018[44]

CHX

60

Caries-affected

Clearfil SE bond (self-etch)

Water

24 hours

CHX 2%

Control

21.7 (16.3)

19.3 (11.9)

6 months

CHX 2%

Control

1.9 (1.8)

2.5 (1.2)

Karrabi and Danesh Kazemi/2016[45]

CHX

120

Caries-free

Adper Single Bond (etch and rinse)

Artificial saliva

6 months

CHX 2%

Control

52.67 (6.86)

28.84 (6.23)

Kasraei et al/2017[46]

RIBO

120

Light activation

Caries-free

Adper Single Bond (etch and rinse)

Water

5,000 thermocycles

RIBO 0.1%

Control

12.79 (3.64)

12.64 (2.35)

Lenzi et al/2014[47]

CHX

60

Caries-free and caries-affected

Adper Single Bond (etch and rinse)

Water

24 hours

CHX 2%

Control

CHX 2% (CA)

Control (CA)

32.8 (3.8)

30.7 (2.2)

25.1 (4.0)

24.3 (3.8)

6 months

CHX 2%

Control

CHX 2% (CA)

Control (CA)

31.3 (2.6)

24.2 (3.6)

23.2 (5.2)

14.3 (5.8)

Li et al/2018[48]

BAI

GD

120

Caries-free

Adper Single Bond 2 (etch and rinse)

Artificial saliva

24 hours

GD 5%

BAI 2.5 μg/mL

Control

58.86 (4.29)

58.32 (3.95)

41.89 (5.18)

3 months

GD 5%

BAI 2.5 μg/mL

Control

56.10 (5.89)

52.43 (5.43)

34.46 (6.22)

6 months

GD 5%

BAI 2.5 μg/mL

Control

51.86 (6.42)

52.43 (5.43)

26.82 (5.30)

Loguercio et al/2016[49]

CHX

60

Caries-free

Primer & Bond NT (etch-and-rinse; PB)

Adper Single Bond 2 (etch and rinse)

Water

24 hours

CHX 2% (PB)

Control

CHX 2% (ASB)

Control

33.1 (2.8)

35.1 (3.1)

43.5 (3.5)

40.2 (3.3)

5 years

CHX 2% (PB)

Control

CHX 2% (ASB)

Control

22.1 (2.2)

11.0 (2.7)

31.3 (2.7)

16.1 (2.1)

Loguercio et al/2009[50]

CHX

15/60

Caries-free

Primer & Bond (etch and rinse)

Adper Single Bond (SB; etch and rinse)

Water

24 hours

CHX 2% (PB) 15 s

CHX 0.002% (PB) 15 s

Control 15 s

CHX 2% (SB) 15 s

CHX 0.002% (SB) 15 s

Control 15 s

CHX 2% (PB) 60 s

CHX 0.002% (PB) 60 s

Control 60 s

CHX 2% (SB) 60 s

CHX 0.002% (SB) 60 s

Control 60 s

33.1 (6.5)

25.7 (2.4)

28.3 (4.3)

43.5 (4.1)

41.4 (4.8)

39.2 (5.4)

31.3 (5.1)

29.2 (3.4)

32.4 (5.4)

41.2 (4.2)

43.2 (6.1)

41.5 (6.4)

6 months

CHX 2% (PB) 15 s

CHX 0.002% (PB) 15 s

Control 15 s

CHX 2% (SB) 15 s

CHX 0.002% (SB) 15 s

Control 15 s

CHX 2% (PB) 60 s

CHX 0.002% (PB) 60 s

Control 60 s

CHX 2% (SB) 60 s

CHX 0.002% (SB) 60 s

Control 60 s

27.3 (4.2)

23.2 (4.1)

20.1 (4.2)

40.1 (5.7)

37.2 (6.1)

27.9 (6.2)

28.1 (4.4)

27.0 (3.6)

21.2 (3.8)

37.6 (3.3)

40.1 (3.7)

25.4 (4.1)

Maravic et al/2018[51]

ACR

60

Caries-free

Adper Scotchbond 1XT (etch and rinse)

Artificial saliva

24 hours

ACR 0.01%

Control

46.6 (3.1)

46.0 (4.9)

12 months

ACR 0.01%

Control

39.9 (3.3)

24.8 (2.4)

Mazzoni et al/2013[52]

EDC

60

Caries-free

Optibond (OB) FL (etch and rinse)

Scotchbond (SB) 1XT (etch and rinse)

Artificial saliva

24 hours

EDC 0.3M + OB

Control

EDC 0.3M + SB

Control

44.5 (9.8)

43.3 (9.4)

38.8 (9.8)

40.5 (10.3)

12 months

EDC 0.3M + OB

Control

EDC 0.3M + SB

Control

41.2 (10.1)

33.1 (7.9)

32.5 (9.6)

24.8 (8.8)

Mazzoni et al/2018[53]

EDC

60

Caries-free

Clearfil SE primer (self-etch)

XP Bond (etch and rinse)

Artificial saliva

24 hours

EDC 0.3M + (Clearfil)

Control

EDC 0.3M + (XP bond)

Control

30.1 (6.3)

32.8 (4.4)

36.5 (7.1)

37.6 (5.9)

12 months

EDC 0.3M + (Clearfil)

Control

EDC 0.3M + (XP bond)

Control

26 (8.0)

21.4 (5.7)

28.6 (6.4)

18.1 (4.9)

Mohamed et al/2020[54]

CS

60

Caries-free

Universal Single Bond adhesive (self-etch)

Water

24 hours

CS 0.2%

CS 2.5%

Control

39.16 (38.62)

15.63 (14.64)

20.82 (21.43)

3 months

CS 0.2%

CS 2.5%

Control

23.95 (25.08)

16.89 (17.79)

21.1 (21.03)

6 months

CS 0.2%

CS 2.5%

Control

25.1 (25.73)

21.36 (20.94)

28.76 (28.15)

Mosallam et al/2018[55]

GT

MA

MN

60

Caries-free

Tetric N-Bond Universal (etch and rinse)

Water

24 hours

GT 20 mg/mL (WE)

GT 5 mg/mL (AE)

MA 20 mg/mL (WE)

MA 5 mg/mL (AE)

MN 20 mg/mL (WE)

MN 5 mg/mL (AE)

Control

29.22 (6.29)

16.70 (5.30)

4.01 (1.92)

26.68 (5.81)

24.90 (6.74)

26.68 (5.81)

28.38 (6.68)

1,000 thermocycles

GT 20 mg/mL (WE)

GT 5 mg/mL (AE)

MA 20 mg/mL (WE)

MA 5 mg/mL (AE)

MN 20 mg/mL (WE)

MN 5 mg/mL (AE)

Control

18.97 (6.66)

12.73 (6.63)

2.64 (2.27)

17.93 (4.82)

17.83 (6.57)

17.93 (4.82)

17.39 (1.71)

Mosallam et al/2019[56]

MA

MN

60

Caries-free

Scotch Bond Universal (etch and rinse)

Water

24 hours

MA 20 mg/mL (WE)

MA 5 mg/mL (AE)

MN 20 mg/mL (WE)

MN 5 mg/mL (AE)

Control

29.30 (7.31)

17.39 (1.63)

35.03 (5.24)

19.72 (8.82)

28.38 (6.68)

1,000 thermocycles

MA 20 mg/mL (WE)

MA 5 mg/mL (AE)

MN 20 mg/mL (WE)

MN 5 mg/mL (AE)

Control

20.55 (8.85)

10.26 (8.28)

20.60 (5.97)

18.05 (7.84)

17.39 (1.71)

Ou et al/2018[57]

CHX

MMP8-I inhibitor

30

Caries-free

Adper Single Bond 2 (etch and rinse)

Water

24 hours

CHX 2%

MMP8-I

Control

42.14 (8.83)

55.29 (9.71)

47.18 (11.69)

6 months

CHX 2%

MMP8-I

Control

41.83 (15.52)

54.70 (13.66)

39.06 (9.88)

12 months

CHX 2%

MMP8-I

Control

39.92 (16.08)

54.29 (15.26)

35.82 (19.14)

Paulose and Fawzy/2018[58]

EDC

60

Caries-free

Adper Scotchbond multipurpose (etch-and-rinse: SBM)

Single bond Universal adhesive (etch and rinse)

Water

24 hours

EDC 0.3M + SBM

Control

EDC 0.3M -dry + SBU

Control

EDC 0.3M -wet + SBU

Control

40.7 (9.3)

43.2 (8.1)

39.7 (5.3)

36.9 (8.7)

30.9 (5.7)

33.6 (6.1)

12 months

EDC 0.3M + SBM

SMP Control

EDC 0.3 -dry + SBU

Control

EDC 0.3M -wet + SBU

Control

30.8 (7.4)

22.3 (7.3)

26.7 (4.9)

18.8 (5.9)

11.2 (4.6)

13.7 (4.6)

Pedrosa et al/2018[59]

CA

60

Caries-free

Adper Scotchbond multipurpose (etch-and-rinse)

Clearfil SE bond (self-etch)

Water

24 hours

CA 0.05% (ASB)

CA 0.1% (ASB)

Control

CA 0.05% (CSE)

CA 0.1% (CSE)

Control

34.40 (7.75)

36.58 (6.16)

40.67 (8.90)

23.47 (6.91)

25.73 (5.55)

31.74 (8.05)

12 months

CA 0.05% (ASB)

CA 0.1% (ASB)

Control

CA 0.05% (CSE)

CA 0.1% (CSE)

Control

26.97 (9.88)

22.88 (4.44)

25.24 (9.72)

24.20 (7.78)

26.21 (7.33)

25.99 (6.79)

Perote et al/2015[60]

CHX

EPE

APE

60

Caries-free

Adper Single Bond 2 (etch and rinse)

Artificial saliva

24 hours

CHX 0.2%

EPE 10%

APE 10%

Control

31.6 (7.0)

29.1 (6.9)

33.0 (6.7)

28.6 (5.3)

6 months

CHX 0.2%

EPE 10%

APE 10%

Control

26.5 (4.4)

23.1 (3.9)

25.1 (4.8)

24.0 (3.9)

Porto et al/2018[61]

CHX

QUE

Res

60

Caries-free

Single Bond Universal (etch and rinse)

Water

24 hours

CHX 2%

Que (μg mL1) 100

250

500

1,000

Res (μg mL1) 100

250

500

1,000

Que + Res (μg mL1) 3:1 100

250

500

1,000

Que + Res 1:1 100

250

500

1,000

Que + Res 1:3 100

250

500

1,000

Control

27.78 (6.88)

32.06 (8.90)

27.51 (8.70)

31.21 (9.93)

31.30 (10.33)

18.81 (6.07)

23.90 (7.46)

23.74 (5.98)

20.11 (5.31)

27.40 (7.19)

19.33 (6.02)

28.44 (7.07)

31.38 (8.45)

18.78 (3.63)

23.93 (7.20)

23.29 (5.23)

19.10 (5.49)

22.73 (6.37)

20.83 (6.61)

25.99 (7.89)

23.76 (5.76)

23.62 (6.71)

3 months

CHX 2%

Que (μg mL1) 100

250

500

1,000

Res (μg mL1) 100

250

500

1,000

Que + Res (μg mL1) 3:1 100

250

500

1,000

Que + Res 1:1 100

250

500

1,000

Que + Res 1:3 100

250

500

1,000

Control

30.68 (8.71)

25.29 (8.01)

34.68 (16.17)

42.37 (13.59)

37.40 (11.37)

31.03 (11.25)

37.90 (10.11)

29.77 (7.34)

26.18 (7.77)

30.48 (10.16)

35.38 (13.54)

31.14 (10.31)

32.32 (8.39)

37.13 (12.29)

32.80 (14.05)

32.36 (11.43)

28.13 (8.54)

28.56 (11.45)

30.82 (8.77)

26.55 (7.93)

31.66 (10.92)

26.47 (8.26)

Prasansuttiporn et al/2020[62]

RA

5

Caries-affected

Clearfil SE Bond (self-etch)

Artificial saliva

24 hours

RA 100 μM

Control

35.4 (5.5)

35.1 (5.3)

12 months

RA 100 μM

Control

34.2 (4.3)

30.3 (4.2)

Prasansuttiporn et al/2017[63]

RA

5

Caries-free

Clearfil SE Bond (self-etch)

Artificial saliva

24 hours

RA 100 μM

Control

54.8 (3.9)

55.2 (4.1)

12 months

RA 100 μM

Control

52.6 (4.7)

45.8 (4.0)

Ruksaphon and Pisol/2017[64]

CHX

RA

60

Caries-free

OptiBond FL (etch and rinse)

OptiBond Solo (solo) (etch and rinse)

Artificial saliva

24 hours

CHX 2% + (solo)

CHX 2% + (FL)

RA 100 μM + (solo)

RA 100 μM + (FL)

Control (solo)

Control (FL)

38.42 (8.04)

38.46 (7.82)

36.00 (8.04)

41.27 (6.76)

39.60 (7.50)

37.27 (8.45)

3 months

CHX 2% + (solo)

CHX 2% + (FL)

RA 100 μM + (solo)

RA 100 μM + (FL)

Control (solo)

Control (FL)

40.75 (7.12)

41.26 (5.51)

39.43 (10.12)

41.27 (6.76)

32.13 (7.32)

29.45 (8.12)

6 months

CHX 2% + (solo)

CHX 2% + (FL)

RA 100 μM + (solo)

RA 100 μM + (FL)

Control (solo)

Control (FL)

32.83 (6.82)

29.33 (6.66)

31.37 (10.24)

32.79 (7.37)

30.54 (8.05)

26.46 (6.39)

12 months

CHX 2% + (solo)

CHX 2% + (FL)

RA 100 μM + (solo)

RA 100 μM + (FL)

Control (solo))

Control (FL)

22.85 (11.72)

27.82 (11.54)

28.98 (7.68)

28.04 (9.09)

3.10 (8.22)

3.91 (9.20)

Sacramento et al/2012[65]

CHX

60

Caries-affected

Clearfil protect Bond (self-etch)

Clearfil SE Bond (self-etch)

Water

24 hours

CHX 2% (SE)

CHX 2% (PB)

Control (SE)

Control (PB)

12.39 (2.37)

14.60 (3.65)

12.28 (2.91)

16.24 (2.71)

6 months

CHX 2% (SE)

CHX 2% (PB)

Control (SE)

Control (PB)

2.88 (1.30)

3.09 (0.92)

2.95 (0.77)

2.32 (0.60)

12 months

CHX 2% (SE)

CHX 2% (PB)

Control (SE)

Control (PB)

1.76 (0.35)

2.34 (0.76)

1.36 (0.22)

1.11 (0.59)

Sadeghi et al/2017[66]

CHX

60

Caries-free

Optibond Solo Plus (etch and rinse)

Single Bond Universal (SBU; etch and rinse)

Water

1 week

CHX 0.2% + OSP

Control

CHX 0.2% +SBU

Control

29.84 (5.43)

34.57 (8.22)

35.75 (8.58)

58.17 (10.25)

6 months

CHX 0.2% + OSP

Control

CHX 0.2% +SBU

Control

20.59 (5.52)

22.51 (3.55)

23.28 (3.90)

33.42 (7.04)

Santiago et al/2013[67]

CHX

EGCG

60

Caries-free

Adper Single Bond 2 (etch and rinse)

Water

24 hours

EGCG 0.02%

EGCG 0.1%

EGCG 0.5%

CHX 2%

Control

31.39 (7.82)

34.74 (9.14)

27.11 (7.78)

34.68 (7.30)

34.17 (7.75)

6 months

EGCG 0.02%

EGCG 0.1%

EGCG 0.5%

CHX 2%

Control

31.75 (10.58)

35.99 (10.91)

31.18 (9.29)

31.62 (5.78)

27.67 (6.98)

Shen et al/2020[68]

CHX

60

Caries-free

Single Bond 2 (etch and rinse)

Water

24 hours

CHX 2%

Control

37.43 (5.29)

33.00 (3.95)

6 months

CHX 2%

Control

33.31 (3.28)

28.36 (4.01)

Venigalla et al/2016[69]

RIBO

EDC

PAC

120

Caries-free

Adper Single Bond water wet bonding (etch and rinse)

Ethanol wet bonding (etch and rinse)

Artificial saliva

24 hours

RIBO 0.1% + WWB

EDC 1M +WWB

PAC 6.5% +WWB

Control

RIBO 0.1% + EWB

EDC 1M + EWB

PAC 6.5% + EWB

Control

46.94 (2.17)

45.14 (1.76)

41.71 (1.63)

31.76 (1.51)

52.12 (0.46)

47.50 (0.78)

44.38 (0.69)

41.61 (1.13)

6 months

RIBO 0.1% + WWB

EDC 1M +WWB

PAC 6.5% +WWB

Control

RIBO 0.1% + EWB

EDC 1M + EWB

PAC 6.5% + EWB

Control

45.14 (1.50)

42.58 (1.24)

34.30 (1.21)

23.96 (1.43)

51.80 (0.32)

45.27 (0.50)

41.90 (0.79)

37.37 (0.58)

Xu et al/2020[70]

BAC

PVPA

PAC

30

Caries-free

Clearfil SE bond (self-etch)

Water

24 hours

MDP 5% + BAC 1%

MDP 5% + PVPA 1,000 μm/mL

MDP 5% + PAC 15%

Control

MDP 15% + BAC 1%

MDP 15% + PVPA 1,000 μm/mL

MDP 15% + PAC 15%

Control

29.2 (6.6)

27.9 (4.1)

26.5 (6.9)

26.9 (5.8)

31.7 (4.0)

30.4 (6.7)

30.3 (3.5)

29.3 (3.8)

12 months

MDP 5% + BAC 1%

MDP 5% + PVPA 1,000 μm/mL

MDP 5% + PAC 15%

Control

MDP 15% + BAC 1%

MDP 15% + PVPA 1,000 μm/mL

MDP 15% + PAC 15%

Control

25.9 (5.2)

26.8 (6.3)

25.6 (4.7)

26.3 (6.2)

35.2 (6.1)

31.8 (5.3)

29.7 (3.6)

31.5 (6.4)

Kazemi-Yazdi et al/2020[71]

CHX

60

Caries-free

Clearfil SE Bond (self-etch)

Water

24 hours

CHX 2%

Control

14.58 (5.04)

18.00 (5.54)

3,000 thermocycles

CHX 2%

Control

14.36 (7.44)

16.71 (8.00)

Da Silva et al/2015[72]

CHX

60

Caries-free

Single Bond 2 (etch and rinse)

Ambar (etch and rinse)

Water

24 hours

CHX 2% (SB)

Control

CHX 2% (Ambar)

Control

21.7 (6.7)

11.4 (3.6)

11.2 (5.9)

12.5 (7.6)

15 days

CHX 2% (SB)

Control

CHX 2% (Ambar)

Control

11.1 (3.6)

6.3 (2.5)

6.8 (4.2)

7.7 (3.6)

Zheng et al/2015[73]

CHX

GT

FeSO4

Galardin

60

Caries-free

Optibond FL (etch and rinse)

Clearfil SE Bond (self-etch)

Artificial saliva

9 months

CHX 2% (FL)

GT 0.05% (FL)

FeSO4 1 mM (FL)

Galardin 0.2 mM (FL)

Control

CHX 2% (SE)

GT 0.05% (SE)

FeSO4 1 mM (SE)

Galardin 0.2 mM (SE)

Control

32.9 (11.3)

33.2 (14.0)

25.3 (10.5)

33.6 (10.5)

25.3 (11.8)

32.9 (11.3)

26.1 (14.2)

25.3 (10.5)

33.6 (14.1)

20.3 (13.6)

Sadek et al/2010[74]

CHX

60

Not mentioned

Scotchbond multipurpose (self-etch)

Single Bond 2 (self-etch)

Experimental ethanol wet-bonding adhesive (self-etch)

Artificial saliva

24 hours

CHX 2% + EWB

Control

CHX 2% + MP

Control

CHX 2% + SB

Control

46.8 (5.1)

45.8 (7.2)

41.3 (8.1)

44.2 (3.5)

42.6 (5.2)

42.3 (7.4)

9 months

CHX 2% + EWB

Control

CHX 2% + MP

Control

CHX 2% + SB

Control

44.6 (5.6)

44.4 (6.9)

37.4 (5.6)

37.4 (3.5)

38.2 (4.7)

44.4 (4.9)

18 months

CHX 2% + EWB

Control

CHX 2% + MP

Control

CHX 2% + SB

Control

43.6 (5.5)

44.2 (7.8)

30.5 (8.0)

32.6 (7.1)

28.8 (8.3)

31.5 (4.3)

Breschi et al/2010[22]

Galardin

30

Caries-free

Adper Scotchbond 1XT (etch and rinse)

Artificial saliva

24 hours

Galardin 0.2 mM

Control

44.1 (7.3)

41.4 (5.9)

12 months

Galardin 0.2 mM

Control

32.4 (6.6)

22.6 (5.4)

Stanislawczuk et al/2009[75]

CHX

60

Caries-free

Prime & Bond NT (etch and rinse)

Single Bond (SB) 2 (etch and rinse)

Water

24 hours

CHX 2% + Prime & Bond

Control

CHX 2% + (SB)

Control

21.9 (4.7)

22.0 (9.7)

23.4 (2.1)

14.6 (3.1)

6 months

CHX 2% + Prime & Bond

Control

CHX 2% + (SB)

Control

31.1 (3.1)

27.2 (6.1)

31.1 (2.6)

20.4 (2.1)

Firouzmandi et al/2020[76]

SDF

180

Caries-free

and

Caries-affected (CA)

Adper single Bond 2 (etch and rinse)

Water

24 hours

SDF 30%

Control

SDF 30% (CA)

Control

17.08 (4.88)

18.37 (4.71)

17.63 (4.19)

12.20 (2.34)

6 months

SDF 30%

Control

SDF 30% (CA)

Control

15.72 (2.34)

14.72 (3.51)

10.30 (3.78)

11.53 (2.66)

Giacomini et al/2017[77]

CHX

E-64

60

Caries-free

Eroded (ERO)

and

Caries-affected (CA)

Adper Single Bond Universal (etch and rinse)

Artificial saliva

24 hours

CHX 2%

CHX 2% (ERO)

CHX 2% (CA)

E-64 5 μM

E-64 5 μM (ERO)

E-64 5 μM (CA)

Control

Control (ERO/water)

Control (CA/water)

28.36 (5.88)

22.53 (4.76)

18.31 (3.50)

28.33 (5.42)

30.23 (6.51)

24.51 (4.41)

35.32 (5.30)

29.85 (4.77)

23.42 (4.95)

6 months

CHX 2%

CHX 2% (ERO)

CHX 2% (CA)

E-64 5 μM

E-64 5 μM (ERO)

E-64 5 μM (CA)

Control

Control (ERO/water)

Control (CA/water)

16.50 (3.89)

20.13 (4.62)

16.50 (3.90)

20.80 (3.71)

27.70 (5.32)

20.80 (3.71)

27.45 (5.33)

26.07 (4.96)

20.28 (3.55)

Sabatini et al/2014[78]

CHX

BAC

60

Caries-free

Adper Single Bond Plus (etch and rinse)

Artificial saliva

24 hours

CHX 2%

BAC 0.5%

BAC 1.0%

Control

38.3 (10.3)

36.4 (8.4)

51.4 (7.9)

34.3 (7.8)

6 months

CHX 2%

BAC 0.5%

BAC 1.0%

Control

34.3 (5.2)

36.6 (6.2)

53.9 (6.9)

27.4 (6.2)

Carvalho et al/2016[79]

CHX

EGCG

60

Caries-affected

Adper Single Bond 2 (etch-and-rinse)

Water

24 hours

EGCG 2%

CHX 2%

Control

23.0 (6.3)

23.3 (6.0)

24.3 (8.6)

6 months

EGCG 2%

CHX 2%

Control

35.7 (8.4)

23.0 (7.2)

21.6 (6.4)

Loguercio et al/2016[80]

CHX

15

Caries-free

Prime & Bond NT (etch and rinse)

Adper Single Bond 2 (etch and rinse)

Water

24 hours

CHX 2% (PB)

Control

CHX 2% (SB)

Control

44.2 (4.3)

42.3 (3.4)

50.3 (5.6)

46.2 (4.7)

2 years

CHX 2% (PB)

Control

CHX 2% (SB)

Control

36.3 (5.1)

23.6 (5.3)

43.3 (3.5)

32.3 (4.5)

Cova et al/2011[99]

RIBO

60

Caries-free

XP Bond adhesive (etch and rinse)

Artificial saliva

24 hours

RIBO 0.1%

Control

44.4 (10.4)

37.3 (10.3)

6 months

RIBO 0.1%

Control

35.6 (11.2)

22.0 (7.0)

12 months

RIBO 0.1%

Control

30.9 (12.2)

17.7 (9)

Mobarak/2011[81]

CHX

60

Caries-free

and

Caries-affected (CA)

Self-etch primer adhesive (Clearfil SE Bond; self-etch)

Artificial saliva

24 hours

CHX 2%

CHX 5%

Control

CHX 2% (CA)

CHX 5% (CA)

Control

23.79 (5.9)

25.94 (6.4)

24.33 (5.1)

20.84 (6.2)

20.59 (5.1)

21.73 (6.0)

2 years

CHX 2%

CHX 5%

Control

CHX 2% (CA)

CHX 5% (CA)

Control

8.74 (3.2)

10.98 (3.3)

9.46 (3.4)

9.99 (3.4)

14.67 (4.5)

9.97 (3.5)

Manso et al/2014[82]

CHX

30

Caries-free

All Bond 3 (Bisco) (etch and rinse)

Excite (Ivoclar Vivadent) (etch and rinse)

Water

24 hours

CHX 2%/water (Bisco)

Control

CHX 2%/ethanol (Bisco)

Control

CHX 2%/water (Excite)

Control

CHX 2%/ethanol (Excite)

Control

46.96 (3.6)

51.07 (3.6)

54.67 (3.6)

59.41 (3.6)

40.05 (5.4)

49.51 (5.4)

53.37 (5.4)

49.67 (5.4)

6 months

CHX 2%/water (Bisco)

Control

CHX 2%/ethanol (Bisco)

Control

CHX 2%/water (Excite)

Control

CHX 2%/ethanol (Excite)

Control

50.69 (3.6)

57.13 (3.6)

52.17 (3.6)

56.41 (3.6)

36.78 (5.4)

42.10 (5.4)

57.47 (5.4)

44.56 (5.4)

15 months

CHX 2%/water (Bisco)

Control

CHX 2%/ethanol (Bisco)

Control

CHX 2%/water (Excite)

Control

CHX 2%/ethanol (Excite)

Control

46.07 (4.4)

47.29 (4.4)

39.58 (4.4)

44.41 (4.4)

40.87 (6.6)

45.51 (6.6)

49.55 (6.6)

42.48 (5.4)

Breschi et al/2010[19]

CHX

30

Caries-free

Adper Scotchbond 1XT (etch and rinse)

Artificial saliva

24 hours

CHX 2%

CHX 0.2%

Control

41.2 (9.6)

39.2 (9.3)

40.8 (8.7)

2 years

CHX 2%

CHX 0.2%

Control

28.5 (7.2)

32.6 (8.3)

13.4 (4.9)

Montagner et al/2015[83]

CHX

60

Caries-free

Adper Single Bond 2 (etch and rinse)

Water

24 hours

CHX 2%

Control

25.3 (6.2)

26.7 (10.0)

18 months

CHX 2%

Control

20.1 (10.3)

14.8 (9.4)

Li et al/2020[84]

DMA

60

Caries-free

Adper Single Bond 2 (etch and rinse)

Water

24 hours

DMA 0.1 mM

DMA 1.0 mM

DMA 10 mM

Control

28.73 (5.19)

30.76 (7.57)

27.06 (7.53)

29.96 (6.43)

1,000 thermocycles

DMA 0.1 mM

DMA 1.0 mM

DMA 10 mM

Control

23.84 (7.06)

29.19 (6.58)

23.34 (7.36)

16.24 (6.90)

Hass et al/2016[98]

PAC

RIBO

GD

60

Caries-free

Adper Single Bond 2 (etch and rinse)

Tetric N-Bond (etch and rinse)

Water

24 hours

PAC 6.5% (SB)

RIBO 0.1% (SB)

GD 5% (SB)

Control

PAC 6.5% (TN)

RIBO 0.1% (TN)

GD 5% (TN)

Control

36.2 (5.5)

37.1 (9.7)

38.5 (2.4)

39.5 (7.9)

29.2 (1.2)

31.5 (6.9)

35.7 (1.9)

36.8 (4.7)

18 months

PAC 6.5% (SB)

RIBO 0.1% (SB)

GD 5% (SB)

Control

PAC 6.5% (TN)

RIBO 0.1% (TN)

GD 5% (TN)

Control

31.9 (4.3)

31.6 (3.5)

29.7 (2.6)

13.9 (1.8)

27.6 (6.3)

25.1 (1.3)

24.2 (1.4)

13.9 (1.8)

Kalagi et al/2020[85]

CHX

5

Caries-free

Adper Scotchbond multipurpose (etch and rinse)

Water

24 hours

CHX 2%

Control

66.4 (8.8)

49.1 (12.6)

6 months

CHX 2%

Control

71.9 (14.7)

41.6 (10.6)

Tekçe et al/2016[86]

CHX

60

Caries-free

Single Bond Universal (self-etch)

All Bond Universal (self-etch)

Water

24 hours

CHX 2% (SBU)

Control

CHX 2% (ABU)

Control

45.22 (6.32)

43.33 (3.41)

38.92 (4.01)

43.81 (3.61)

12 months

CHX 2% (SBU)

Control

CHX 2% (ABU)

Control

41.19 (3.98)

37.67 (3.40)

31.37 (5.97)

38.54 (6.19)

de Moura et al/2021[87]

GT

60

Caries-affected

Adper Single Bond 2 (etch-and-rinse)

Water

24 hours

GT 0.05%

GT 0.2%

GT 2%

Control

14.42 (6.20)

17.80 (6.49)

11.04 (2.94)

11.29 (4.78)

6 months

GT 0.05%

GT 0.2%

GT 2%

Control

9.53 (4.83)

13.25 (5.82)

7.09 (4.14)

8.82 (6.23)

Li et al/2021[88]

DMA

60

Caries-free

Adper Single Bond 2 (etch-and-rinse)

Water

24 hours

DMA 1 mM

DMA 5 mM

DMA 10 mM

Control

33.16 (8.41)

32.59 (8.70)

32.73 (7.39)

30.08 (7.55)

10,000 thermocycles

DMA 1 mM

DMA 5 mM

DMA 10 mM

Control

30.40 (8.10)

31.46 (7.31)

31.85 (8.10)

22.63 (6.40)

Abbreviations: ACR, acrolein; AE, alcohol extract; APE, aqueous propolis extract; BAI, baicalein; BAC, benzalkonium chloride; CA, caffeic acid; CS, chitosan; CHX, chlorhexidine; DCC, N,N'-dicyclohexylcarbodiimide; DMA, dopamine methacrylamide; EDC, carbodiimide; EGCG, epigallocatechin gallate; EPE, ethanolic propolis extract; FeSO4, ferrous sulfate; GD, 5% glutaraldehyde; GT, green tea; HES, hesperidin; MA, Morus alba leaves; MAP, mussel adhesive protein; MN, Morus nigra leaves; NAR, naringin; PAC, proanthocyanidin; PVPA, polyvinylphosphonic acid; QUE, guercetin; RA, rosmarinic acid; Res, resveratrol; RIBO, riboflavin; RUT, rutin; SDF, silver diamine fluoride; WE, water extract.


Thirty-one different types of MMP inhibitors were used, 14 synthetically derived and 17 naturally derived. The microtensile bond strength test was used in all included studies except for five studies that used microshear bond strength testing. Most studies (n = 53) used caries-free dentine substrate, 13 used caries-affected dentine, two studies used eroded dentine, and one study used dentine without mentioning its condition. All studies used permanent teeth except for one study that used primary teeth.

With respect to storage medium, the majority of studies used distilled water (40 studies) and 22 used artificial saliva. Two studies used both distilled and deionized water. The majority of the studies applied MMP inhibitor for 60 s (n = 47), six studies applied it for 30 seconds, four for 120 seconds, three for 5 seconds, two for 15 seconds, and one each for 20 and 180 seconds. One study did not report the application duration. Only MMP inhibitors applied for 30 and 60 seconds were included in the meta-analysis, as they contained enough data.

Ageing periods ranged from 24 hours to 5 years, and various thermocycling ageing protocols were also used. The majority of studies (n = 62) aged samples for 24 hours as an immediate ageing period. With respect to long-term ageing, 31 studies aged the samples for 6 months, 19 aged them for 12 months, five aged them for 3 months, three for 2 years, three for 18 months, two for 9 months, and one study each for 3 days, 1 week, 15 days, 15 months, and 5 years. Eleven studies used thermocycling for ageing: four used 1,000 cycles, two used 5,000 cycles, and one study each used 2,500, 3,000, 10,000, and 25,000 cycles.


Risk of Bias Evaluation

[Table 3] shows the evaluated risk of bias of the included studies. Overall, almost half of included studies showed a medium risk of bias (33 of 64), 17 of 64 studies showed a high risk of bias, and 14 studies were classified as a low risk of bias.

Table 3

Quality assessment and risk of bias

Study/year

Randomization

Substrate condition

Dentine pretreatment duration

Manufacturer instruction

Storage medium

Interface surface area

Single operator

Sample size calculation

Blinding of operator

Risk of bias

Baena et al/2020 [30]

N

Y

Y

Y

Y

Y

N

N

N

High

Balloni et al/2017[31]

Y

Y

Y

Y

Y

Y

N

N

Y

Medium

Bravo et al/2017 [32]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

de Faria Teixeira et al/2015 [33]

Y

N

Y

Y

Y

Y

N

N

N

High

Comba et al/2020 [34]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Czech et al/2019 [24]

Y

Y

Y

Y

Y

Y

Y

N

N

Medium

Dávila-Sánchez et al/2020 [35]

Y

Y

Y

Y

Y

Y

Y

Y

N

Low

Costa et al/2019 [36]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

El Baz, and Aboulenien/2018[37]

N

Y

Y

Y

Y

Y

N

Y

N

Medium

Fang et al/2017 [38]

N

Y

Y

Y

Y

Y

N

N

N

High

Fernandes et al/2021[39]

Y

Y

Y

Y

Y

Y

N

Y

N

Medium

Fialho et al/2019 [40]

Y

Y

Y

Y

Y

Y

Y

Y

N

Low

Gerhardt et al/2016 [41]

Y

Y

Y

Y

Y

N

N

N

N

High

Campos et al/2019 [42]

Y

Y

N

Y

Y

Y

Y

N

N

Medium

Giacomini et al/2020 [43]

Y

Y

Y

Y

Y

Y

N

Y

N

Medium

Grandizoli and Pinheiro/2018[44]

Y

Y

Y

Y

Y

Y

N

Y

N

Medium

Karrabi and Danesh Kazemi/2016 [45]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Kasraei et al/2017 [46]

Y

Y

Y

N

Y

Y

N

N

N

High

Lenzi et al/2014 [47]

Y

Y

Y

N

Y

Y

N

N

N

High

Li et al/2018 [48]

Y

Y

Y

N

Y

Y

N

N

N

High

Loguercio et al/2016 [49]

Y

Y

Y

N

Y

Y

N

N

N

High

Loguercio et al/2009 [50]

Y

Y

Y

Y

Y

Y

Y

N

N

Medium

Maravic et al/2018 [51]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Mazzoni et al/2013 [52]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Mazzoni et al/2018 [53]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Mohamed et al/2020 [54]

N

Y

Y

Y

Y

Y

N

N

N

High

Mosallam et al/2018 [55]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Mosallam et al/2019 [56]

Y

Y

Y

Y

Y

N

N

N

N

High

Ou et al/2018 [57]

Y

Y

Y

Y

Y

N

N

N

N

High

Paulose and Fawzy/2018 [58]

Y

Y

Y

Y

Y

Y

N

N

N

High

Pedrosa et al/2018 [59]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Perote et al/2015 [60]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Porto et al/ 2018 [61]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Prasansuttiporn et al/2020 [62]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Prasansuttiporn et al/2017 [63]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Ruksaphon and Pisol/2017 [64]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Sacramento et al/2012 [65]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Sadeghi et al/2017 [66]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Santiago et al/2013 [67]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Shen et al/2020 [68]

Y

Y

Y

N

Y

Y

N

N

N

High

Venigalla et al/2016 [69]

Y

Y

Y

Y

Y

N

N

N

N

High

Xu et al/2020 [70]

Y

Y

Y

N

Y

Y

N

N

N

High

Kazemi-Yazdi et al/2020 [71]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Da Silva et al/2015 [72]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Zheng et al/2015 [73]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Sadek et al/2010 [74]

Y

N

Y

Y

Y

Y

N

N

N

High

Breschi et al/2010 [22]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Stanislawczuk et al/2009 [75]

Y

Y

Y

N

Y

Y

Y

N

N

Medium

Firouzmandi et al/2020 [76]

N

Y

Y

Y

Y

N

N

N

N

High

Giacomini et al/2017 [77]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Sabatini et al/2014 [78]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Carvalho et al/2016 [79]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Loguercio et al/2016 [80]

Y

Y

Y

Y

Y

Y

Y

N

N

Medium

Cova et al/2011 [99]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Mobarak/2011 [81]

N

Y

Y

Y

Y

N

N

N

N

High

Manso et al/2014 [82]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Breschi et al/2010 [19]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Montagner et al/2015 [83]

Y

Y

Y

Y

Y

Y

Y

N

N

Medium

Li et al/2020 [84]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Hass et al/2016 [98]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Kalagi et al/2020 [85]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Tekçe et al/2016 [86]

Y

Y

Y

Y

Y

Y

Y

N

N

Medium

de Moura et al/2021 [87]

Y

Y

Y

Y

Y

Y

Y

Y

N

Low

Li et al/2021 [88]

Y

Y

Y

Y

Y

Y

N

N

N

Medium

Abbreviations: N, no; Y, yes.


Note: This table demonstrates the quality assessment and risk of bias as reported in the materials and methods section.




Meta-Analysis

Of the 64 studies, data from 42 studies were subjected to further evaluation in meta-analyses ([Figs. 2] [3] [4] [5] [6]). In the first analysis (2% CHX vs. control in the baseline, immediate bond strength values), 16 etch-and-rinse studies were included, representing 28 datasets considered. There was no statistically significant difference between groups (Z-test = 1.26, p = 0.21), and there was considerable heterogeneity (I2  = 54%). Eight self-etching studies were included, with 11 datasets considered. There was no significant difference between groups (Z-test = 0.76, p = 0.45), and there was moderate heterogeneity (I2  = 35%). Overall (self-etching and etch-and-rinse), there was no statistically significant difference between groups (Z-test = 1.51, p = 0.13), with moderate heterogeneity observed between subgroups (I2  = 49%; [Fig. 2A]).

Zoom
Fig. 2 Forest plots according to MMP inhibitor type. 2% CHX vs. control at 24 hours (A), 6 months (B), and 12 months (C). CHX, chlorhexidine; CI, confidence interval; MMP, matrix metalloproteinase; SD, standard deviation.
Zoom
Fig. 3 Forest plots according to MMP inhibitor type. 0.3 M EDC vs. control at 24 hours (A) and 12 months (B). CI, confidence interval; EDC, carbodiimide; MMP, matrix metalloproteinase; SD, standard deviation.
Zoom
Fig. 4 Forest plots according to MMP inhibitor type: 0.1% RIBO vs. control at 24 hours (A) and 6 months (B). CI, confidence interval; MMP, matrix metalloproteinase; RIBO, riboflavin; SD, standard deviation.
Zoom
Fig. 5 Forest plots according to pretreatment duration for 30 seconds: pretreatment with 2% CHX vs. control group at 24 hours (A) and 6 months (B). CHX, chlorhexidine; CI, confidence interval; SD, standard deviation.
Zoom
Fig. 6 Forest plots according to pretreatment duration for 60 seconds: pretreatment with 2% CHX vs. control group at 24 hours (A) and 6 months (B). CHX, chlorhexidine; CI, confidence interval; SD, standard deviation..

The second analysis (2% CHX vs. control at 6 months of ageing) included 14 etch-and-rinse studies, representing 25 datasets. There was overall a higher bond strength for the experimental group compared with controls, but this was not statistically significant (Z-test 1.81, p = 0.07) and heterogeneity was considerable (I2  = 88%). Six self-etching studies were included, with nine datasets considered. There was no statistically significant difference between groups (Z-test = 0.86, p = 0.39), and again there was considerable heterogeneity (I2  = 73%). Tests for overall effect showed significantly higher bond strength in the experimental group compared with controls (Z-test = 2.33, p = 0.02), with considerable heterogeneity between subgroups (I2  = 86%; [Fig. 2B]).

The third analysis (2% CHX vs. control at 12 months of ageing) included five etch-and-rinse studies with seven datasets. There were overall higher bond strength values in the experimental group compared with the control group. but this was not statistically significant (Z-test = 1.09, p = 0.28) and heterogeneity was considerable (I2  = 91%). For self-etching, three studies were included with four datasets considered, and there was no statistically significant difference between groups (Z-test = 0.18, p = 0.86) but with considerable heterogeneity (I2  = 84%). Tests for overall effect favored the experimental group over the control group but without statistical significance (Z-test = 1.66, p = 0.10) and with considerable heterogeneity between subgroups (I2  = 90%; [Fig. 2C]).

For the fourth analysis (0.3 EDC vs. control at baseline), only etch-and-rinse studies met the inclusion criteria. Three studies were included, representing six datasets. Overall, the effect was not statistically significant (Z-test = 0.33, p = 0.74). Heterogeneity between groups was low (I2  = 0%; [Fig. 3A]).

For the fifth analysis (0.3 EDC vs. control at 12 months), again, three etch-and-rinse studies representing six datasets were included. Overall, there were significantly higher bond strength values in the experimental group compared with the control group (Z-test = 2.58, p = 0.01) but with considerable heterogenicity (I 2 = 66%; [Fig. 3B]).

For the sixth analysis (0.1% RIBO vs. control at baseline), only two etch-and-rinse studies met the criteria, representing three datasets. There was overall a significant difference favoring the experimental group over the control group (Z-test = 3.12, p = 0.002), with considerable heterogeneity (I2  = 99%; [Fig. 4A]).

For the seventh analysis (0.1% RIBO vs. control at 6 months), two studies representing three datasets showed significantly higher bond strengths in the experimental group than the control group (Z-test = 5.78, p < 0.00001) but with considerable heterogeneity I2  = 98% ([Fig. 4B]).

For the eighth analysis of pretreatment for 30 seconds (2% CHX vs. control at baseline), only four etch-and-rinse studies were included, representing seven datasets. There was overall a statistically significant difference favoring the control group over the experimental group (Z = 2.42, p = 0.02), and heterogeneity was low (I2  = 0%; [Fig. 5A]).

For the ninth analysis of pretreatment for 30 seconds (2% CHX vs. control at 6 months), only three etch-and-rinse studies met the criteria, representing six datasets. There was overall no statistically significant difference between groups (Z = 0.28, p = 0.78), and heterogeneity was considerable (I2  = 55%; [Fig. 5B]).

For the 10th analysis of pretreatment for 60 seconds (2% CHX vs. control at baseline), 14 etch-and-rinse studies were included, representing 19 datasets. There was overall no statistically significant difference between groups (Z-test = 0.07, p = 0.95), but there was considerable heterogeneity between groups (I2  = 63%). For self-etching, six studies were included with six datasets. Again, there was no statistically significant difference between groups (Z-test = 0.01, p = 0.89) and moderate heterogeneity (I2  = 41%). Tests for overall effect showed no statistically significant difference between groups (Z-test = 0.01, p = 0.99) and considerable heterogeneity between subgroups (I2  = 58%; [Fig. 6A]).

For the 11th and final analysis of pretreatment for 60 seconds (2% CHX vs. control at 6 months), 11 etch-and-rinse studies were included, representing 16 datasets. Overall, the experimental group was slightly, but not significantly, favored over the control group (Z-test = 1.73, p = 0.08), with considerable heterogeneity (I2  = 91%). Five self-etching studies were included representing five datasets. Overall, the experimental group was slightly, but not significantly, favored over the control group (Z-test = 1.22, p = 0.22), with considerable heterogeneity (I2  = 83%). The tests for overall effect favored the experimental group but this was not statistically significant (Z-test = 2.35, p = 0.73). Heterogeneity between subgroups was considerable (I2  = 90%; [Fig. 6B]).


Discussion

This meta-analysis revealed that at least some MMP inhibitors significantly alter bond strength, both immediately and over the longer term. Accordingly, the null hypothesis was rejected.

Of all MMP inhibitors considered for meta-analysis, two MMP inhibitors improved bond strength: 0.3 M EDC and 0.1% RIBO. The 0.3 M EDC did not improve bond strength immediately (24 hours) but showed benefit after ageing for 12 months, while 0.1% RIBO showed statistically significant increases in bond strength both immediately (24 hours) and over the long term (6 months) compared with controls. Conversely, 2% CHX showed a slight but nonsignificant improvement in bond strength after 6 months of ageing but not immediately (24 hours) or after 12 months. The lack of immediate benefit with 2% CHX is consistent with two previous meta-analyses,[28] [89] but the long-term results differ, possibly due to the different concentration of CHX used in previous studies. It has been suggested but not consistently proven that MMP inhibition by CHX is dose dependent.[90] [91] It is worth noting that, of the few clinical trials evaluating pretreatment with CHX, no improvement in bond strength was observed over time.[92] [93] [94] [95] [96] [97] With respect to adhesive systems, a previous systematic review[28] found that both types of adhesive system (self-etching and etch and rinse) benefited from 2% CHX in vitro. This, however, was also not consistent with the current meta-analysis results, since we found no significant difference according to the adhesive system used.

EDC and RIBO have a different mechanism of MMP inhibition to CHX through their cross-linking action. Generally, collagen cross-linkers protect collagen fibrils from further degradation by enhancing both the chemical and mechanical properties of collagen.[98] [99] [100] These additional functions could explain their superiority in maintaining adhesive interface integrity.

Pretreatments of 30 and 60 seconds with 2% CHX met the inclusion criteria for meta-analysis. Generally, neither pretreatment protocol significantly improved bond strength either immediately (24 hours) or over the long term (6 months). Indeed, when 2% CHX was applied for 30 seconds, there was a significant negative effect on bond strength over 24 hours. After 6 months of aging, there was a slight improvement in bond strength, still favoring the control group. With pretreatments of 60 seconds, 2% CHX showed no effect on bond strength and was similar to controls and, while slightly improved bond strength was observed with CHX after 6 months, it was nevertheless not statistically significant.

Our results show some inconsistencies with previous systematic reviews which might be due to differences in the inclusion criteria. For example, Montagner et al[28] and Kiuru et al[89] included different concentrations of CHX other than 2%, as well as various bond strength tests other than microtensile bond strength testing.


Limitations

There are a few limitations to our study. This review only included in vitro studies since there have been very few in vivo studies or clinical trials in the literature. More in vivo studies will ultimately be crucial for providing high-quality evidence of the safety, toxicity, and efficacy of a given intervention in a complex model. Furthermore, although strict measures were taken during the search of the articles included for meta-analysis, several data demonstrated high heterogeneity. It is worth mentioning that most of the results with high heterogeneity were observed in the long-term ageing periods, unlike the immediate ageing periods which showed lower heterogeneity. Factors that could influence this may include the different brands of adhesive systems used and the ageing methods utilized. Similar findings were observed in the study by Montagner et al[28] which found that the aging methods were the greater influencing factor in the high heterogeneity. It is also worth noting that there are no standardized protocols for evaluating bond strength which previously shown will inevitably increase the heterogeneity of results [101]. To improve the reliability and quality of future bond strength testing studies, robust and strict guidelines for laboratory testing must be developed and implemented.

Many of the studies carried a risk of bias, and only one study mentioned blinding of the operator testing the bond strength; this parameter will be important to include in future studies to reduce the risk of bias. Moreover, only six studies calculated the sample size and reported a power analysis.

Nevertheless, these in vitro findings pave the way for rationale clinical trialing of dentine surface pretreatment with MMP inhibitors to improve clinical outcomes.


Conclusion

The data suggest that using 2% CHX had no significant positive effect on bond strength either immediately or over the longer term. Pretreatments with 2% CHX for either 30 or 60 seconds do not improve the bond strength. Both 0.3 M EDC and 0.1% RIBO improve bond strength immediately and over time. There was considerable heterogeneity between the different adhesive systems used, limiting our meta-analysis. Given the limited clinical evidence available, more research is required to confirm the beneficial use of MMP inhibitors.



Conflict of Interest

None declared.

Acknowledgment

The authors would like to thank Kalvin Balucanag for support with meta-analyses.


Address for correspondence

Hasan Jamal, BA, MSc, MSc, DClinDent, MPaed
Paediatric Dentistry Department, Eastman Dental Institute, University College London
London WC1E 6DE
United Kingdom   

Publikationsverlauf

Artikel online veröffentlicht:
18. November 2022

© 2022. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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Fig. 1 PRISMA 2020 flowchart diagram of study selection.[27] PRISMA, Preferred Reporting Items for Systematic Review and Meta-analyses.
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Fig. 2 Forest plots according to MMP inhibitor type. 2% CHX vs. control at 24 hours (A), 6 months (B), and 12 months (C). CHX, chlorhexidine; CI, confidence interval; MMP, matrix metalloproteinase; SD, standard deviation.
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Fig. 3 Forest plots according to MMP inhibitor type. 0.3 M EDC vs. control at 24 hours (A) and 12 months (B). CI, confidence interval; EDC, carbodiimide; MMP, matrix metalloproteinase; SD, standard deviation.
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Fig. 4 Forest plots according to MMP inhibitor type: 0.1% RIBO vs. control at 24 hours (A) and 6 months (B). CI, confidence interval; MMP, matrix metalloproteinase; RIBO, riboflavin; SD, standard deviation.
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Fig. 5 Forest plots according to pretreatment duration for 30 seconds: pretreatment with 2% CHX vs. control group at 24 hours (A) and 6 months (B). CHX, chlorhexidine; CI, confidence interval; SD, standard deviation.
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Fig. 6 Forest plots according to pretreatment duration for 60 seconds: pretreatment with 2% CHX vs. control group at 24 hours (A) and 6 months (B). CHX, chlorhexidine; CI, confidence interval; SD, standard deviation..