efficacy of varying concentrations of subgingivally delivered metformin in the treatment of chronic...

Efficacy of Varying Concentrationsof Subgingivally Delivered Metforminin the Treatment of Chronic Periodontitis:A Randomized Controlled Clinical TrialA.R. Pradeep,* Nishanth S. Rao,* Savitha B. Naik,† and Minal Kumari*

Background: Metformin (MF), a second-generation bigua-nide, is a commonly used oral antidiabetic drug that hasbeen shown recently to stimulate osteoblasts and reducealveolar bone loss. The present study aims to explore theefficacy of 0.5%, 1%, and 1.5% MF gel as a local drug deliv-ery system in adjunct to scaling and root planing (SRP)for treatment of intrabony defects (IBDs) in patients withchronic periodontitis.

Methods: A total of 118 IBDs were treated with 0.5%, 1%,or 1.5%MF gel or placebo gel. Clinical parameters (modifiedsulcus bleeding index, plaque index, probing depth [PD], andclinical attachment level [CAL]) were recorded at baseline, 3months, and 6 months, whereas radiographic parameterswere recorded at baseline and 6 months. IBD depth at base-line and 6 months was calculated on standardized radio-graphs by using the image analysis software. The meanconcentration of MF in gingival crevicular fluid was esti-mated by reverse-phase high-performance liquid chroma-tography.

Results: Mean PD reduction and mean CAL gain wasfound to be greater in MF groups than the placebo group atboth 3 and 6 months. Furthermore, significantly greater re-duction of IBD depth was found in the MF groups comparedto the placebo group, with greatest reduction in 1% MF.

Conclusions: The results of the present study show thatlocal delivery of MF into the periodontal pocket stimulatedsignificant increase in the PD reduction, CAL gain, and im-proved IBD depth reduction compared to placebo in adjunctto SRP. This can provide a new direction in the field of peri-odontal healing. J Periodontol 2013;84:212-220.

KEY WORDS

Chronic periodontitis; clinical trials; drug delivery systems;Metformin; radiography; regeneration.

Periodontal disease is a chronic in-flammatory disease characterizedby inflamed gingiva, bleeding on

probing, resorption of alveolar bone, andattachment loss between the tooth andits surrounding alveolar bone. In the pastdecade, periodontal disease has beenrecognized as not merely a local in-fectious disease but as a chronic, sub-clinical, inflammatory disease for thehost.1

There are no conventional periodontaland surgical treatments which can re-generate lost periodontal tissue toa significant clinical degree. Therefore,establishing new therapeutic proceduresthat enable the complete regenerationof periodontal tissue once destroyed bythe periodontal disease progression is animportant task.2

Diabetes mellitus is a clinically andgenetically heterogeneous group of meta-bolic disorders manifested by abnormallyhigh levels of glucose in the blood.3 Met-formin HCl (1,1-dimethylbiguanide HCl)(MF), is one of the most commonly usedoral antihyperglycemic agents for thetreatment of type II diabetes mellitus.MF is a second-generation biguanidethat decreases blood glucose levels bydecreasing hepatic glucose production(inhibition of gluconeogenesis) and de-creasing peripheral insulin resistance.The mechanism of action appears to bemainly at the hepatocyte mitochondria,

* Department of Periodontics, Government Dental College and Research Institute,Bangalore, India.

† Department of Conservative Dentistry and Endodontics, Government Dental College andResearch Institute.

doi: 10.1902/jop.2012.120025

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in which MF interferes with intracellular handling ofcalcium, decreasing gluconeogenesis and increasingexpression of glucose transporters.4 In 1995, the Foodand Drug Administration approved MF for use in theUnited States, which led to a significant increase inclinical use.5 It is currently recommended as first-linetherapy in overweight or obese patients with thiscondition.6 Several sites of action have been pro-posed for MF, including decreased hepatic glucoseoutput, increased peripheral glucose uptake, and im-proved insulin secretion (Bailey and Turner, 1996).7

MF was shown to inhibit cytosolic and mitochondrialreactive oxygen species production induced by ad-vanced glycation end products in endothelial andsmooth muscle cells (Bellin et al., 2006).8 The U.K.Prospective Diabetes Study9 showed that MF treat-ment reduces the risk of life-threatening macrovascularcomplications compared to other antihyperglycemicagents.

However, recent research has shed light on a noveltherapeutic action of MF in stimulating osteoblasticdifferentiation and bone formation.10,11 In a recent in-vitro study,10 the effects of MF on the growth and dif-ferentiation of osteoblasts in culture were evaluated.Treatment of two osteoblast-like cells (UMR106 andMC3T3E1) with MF (25 to 500 mM) for 24 hours led toa dose-dependent increase of cell proliferation. MF alsopromoted osteoblastic differentiation: it increasedtype I collagen production in both cell lines and stim-ulated alkaline phosphatase activity in MC3T3E1osteoblasts. In addition, MF markedly increased theformation of nodules of mineralization in 3-weekMC3T3E1 cultures. MF induced activation and re-distribution of phosphorylated extracellular signal-regulated kinase in a transient manner and dose de-pendently stimulated the expression of endothelialand inducible nitric oxide synthases. In another studyonligature-inducedperiodontitis,11 theMFtreatmentofrats induced a significant reduction in alveolar boneloss compared to vehicle-treated rats. With regard toosteoblast differentiation, MF augmented the miner-alization of MC3T3E1 cells approximately two-foldversus the non-treated cells. However, MF was shownto exert no effects on osteoclast formation induced by1,25-dihydroxyvitaminD3, lipopolysaccharide, andprostaglandin E2. Moreover, MF exerted no effect onadipocyte differentiation.

To the best of our knowledge, there are no publisheddata on the usage of local drug delivery using MFwith gellan gum (as a vehicle) for direct placementin the periodontal pocket of patients with chronicperiodontitis (CP). Considering the above facts,the current study is designed as a single-center,randomized, controlled clinical trial to evaluate theefficacy of 0.5%, 1%, and 1.5% MF gel as local drugdelivery in adjunct to scaling and root planing (SRP)

for the treatment of intrabony defects (IBDs) in pa-tients with CP compared to placebo gel.

MATERIALS AND METHODS

Source of DataThe patients for this study were selected from theoutpatient section of the Department of Periodon-tics, Government Dental College and Research In-stitute, Bangalore, India, and the studywas performedfrom January 2011 through September 2011. Forty-one patients, (20 males and 21 females, aged 30 to50 years;mean age –SD: 37.2 – 2.6 years) diagnosedwith CP,12 were enrolled in this study. It was madeclear to the potential patients that participation wasvoluntary. Written informed consent was obtainedfrom patients, and ethical clearance for the study wasreceived from the Institutional Ethical Committeeand Review Board of the Government Dental Collegeand Research Institute, Bangalore, India.

Selection CriteriaSystemically healthy patients with sites showingprobing depth (PD) ‡5 mm, clinical attachment level(CAL) ‡4 mm, and vertical bone loss ‡3 mm on in-traoral periapical radiographs with no history of peri-odontal therapy or use of antibiotics in the preceding6 months were included. The exclusion criteria in-cluded the following: 1) patients with known systemicdisease; 2) known or suspected allergy to the MF/biguanide group; 3) patients on systemicMFor otheroral antidiabetic therapy; 4) patients with aggres-sive periodontitis; 5) patients with diabetes; 6) useof tobacco in any form; 7) alcoholism; 8) immuno-compromised patients; and 9) pregnant or lactatingfemales.

After participant enrollment by an examiner (ARP),patients were randomly assigned to either placebo ortest groups (0.5% MF, 1% MF, and 1.5% MF), and allsites meeting inclusion criteria were divided into theplacebo and test groups, with 30 sites in placebo and0.5% MF groups (10 patients in each group) and 29sites in 1% (10 patients) and 1.5% (11 patients) MFgroups. The randomization process was made exter-nally by the statistical unit using a computer-generatedrandom table, and investigators were not involved inthe randomization process, nor were they aware ofthe assigned group in all outcome evaluations. In thetest groups, sites were treated with SRP, followed by0.5%,1%, and1.5%MFgel local drugdelivery,whereasin the placebo group, sites were treated with SRP,followed by placebo gel placement. Multiple sitesfrom upper and lower posteriors per patient wereenrolled for either the MF or placebo group. Patientswere masked for allocation into the MF or placebogroup. SRP was performed under local anesthesia atbaseline until the root surface was considered smooth

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and clean by the operator (NSR) using curets.‡ Noantibiotics and/or anti-inflammatory agents wereprescribed after treatment. Clinical parameters, in-cluding modified sulcus bleeding index13 (mSBI),full-mouth and site-specific plaque score14 (PI), PD,and CAL, were recorded at baseline (before theSRP) and at 3 and 6 months. A custom-made acrylicstent and a color-coded periodontal probe§ wereused to standardize the measurement of clinicalparameters. All pretreatment and post-treatmentclinical parameters were recorded by an examiner(ARP) who was masked to the type of treatmentreceived by the patients, whereas another clinician(NSR) provided treatment to both groups.

Intra-Examiner CalibrationIntra-examiner calibration was achieved by exa-mination of 20 sites twice, 24 hours apart, beforebeginning the study. Calibration was accepted ifmeasurements at baseline and 24 hours were similarto 1 mm at the 95% level.

Formulation of MF GelAfter intensive in vitro investigations for optimizationand stability, the MF gel was developed at the Al-Ameen College of Pharmacy, Bangalore, India.

MF gel was prepared as described by Mohapatraet al.15 Briefly, all the required ingredients of the for-mulation were weighed accurately. Dry gellan gumpowder was dispersed in distilled water maintained at95�C. The dispersion was stirred at 95�C for 20 minutesusing a magnetic stirreri to facilitate hydration ofgellan gum. The required amount of mannitol wasadded to the gellan gum solution with continuousstirring, and the temperature was maintained above80�C. A weighed amount of MF was added with stir-ring. Then sucralose, citric acid, and preservatives(methylparaben, propylparaben) were added withstirring. Finally, the required amount of sodium cit-rate was dissolved in 10 mL distilled water and addedto the mixture. The mixture was allowed to cool toroom temperature to form gel. The gels were preparedusing three different concentrations of MF (0.5%, 1%,and 1.5%).

Local Drug DeliveryFor standardization, 10 mL prepared MF gel was in-jected into the periodontal pockets using a syringewith a blunt cannula. Patients were instructed to re-frain from chewing hard or sticky foods, brushingnear the treated areas, or using any interdental aidsfor 1 week. Adverse effects were noted at recall visits,and any supragingival deposits were removed.

Collection of Gingival Crevicular FluidSamples of gingival crevicular fluid (GCF) were col-lected from drug-delivery sites in six randomly se-lected patients each from the MF groups (0.5%, 1%,

and 1.5% MF) using 1- to 5-mL calibrated volumetricmicrocapillary pipettes¶ at baseline and at 2, 4, 6, and24 hours, and on days 2, 7, 14, 21, and 30. Collectedsamples were stored at 4�C to 8�C until the estimationwas done.

Radiographic Assessment of IBDsThe depth of IBD was evaluated at baseline and 6months using an image analyzer.# IBD depth wasmeasuredon the radiographbymeasuring the verticaldistance from the crest of the alveolar bone to thebase of the defect. Individually customized bite blocksand a parallel-angle technique were used to obtainfilms as reproducible as possible. All radiographswere reviewed in a single reference center by a maskedevaluator (MK). For assessment, radiographs werescanned with a scanner** of 6,400 dpi by the sameevaluator who was masked to the treatment pro-cedure performed in the patients. The radiographicIBD depth was measured by a computer-aidedsoftware program as used previously.16,17

Primary and Secondary Outcome MeasuresThe primary outcome of the present study was com-plete bone defect fill. The secondary outcomes in-cluded PD, CAL, mSBI, and PI.

Estimation of Quantity of MFThe drug estimation was done using gradientreverse-phase high-performance liquid chromatog-raphy†† (HPLC) with pumps, a variable wavelengthprogrammable ultraviolet/visible spectroscopy de-tector, and a system controller; an operating soft-ware data station‡‡ was used.

Chromatographic ConditionsA column§§ (150-mm length, 4.6-mm internal di-ameter, and 5-mm particle size) was used as thestationary phase. The mobile phase consisted ofacetonitrile–potassium dihydrogen phosphate buffer(pH 6.5) (34:66, volume/volume) and 3 mM sodiumdodecyl sulfate. The mobile phase was filteredthrough a 0.45-mm membrane filterii and sonicatedtoremoveairbubbles.Theflowratewas0.7mL/minute,and the column effluent was monitored at 236 nm.

Sample Preparation and Calibration CurveA stock solution of 5 mg/mL MF was prepared bydissolving 100 mg in 20 mL water. Working solutions

‡ Hu-Friedy, Chicago, IL.§ UNC-15, Hu-Friedy.i Magnetic stirrer 2MLH, Remi, Mumbai, India¶ Sigma-Aldrich, St. Louis, MO.# Scion Image Analyzer, Scion, Frederick, MD.** HP Scanjet 3c/I, Hewlett Packard, Singapore.†† 1200 Series, Agilent Technologies, Palo Alto, CA.‡‡ Agilent Dissolution Testing UV-visible ChemStation Software

(G1118AA), Agilent Technologies.§§ Agilent HPLC Columns/Zorbax Column Compartment SL support,

Agilent Technologies.ii Sartorius, Goettingen, Germany.

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were prepared freshly on the day of experiment fromthe stock by successive dilutions with water, and thissolutionwasadded toGCFsamples.All solutionswerestored at 48�C and protected from light.

GCF was transferred to a 1- to 5-mL centrifugetube containing 20 mL internal standard solution. An80 mL volume of 10 M NaOH was added to alkalinizethe media. Analytes were then extracted using a3-mL mixture of 1-butanol/hexane (50:50 volume/volume). The tubes were vortex mixed for 30 seconds

and centrifuged at 3,000 · g for 3 minutes Thesupernatant (organic layer) was transferred intoclean glass tubes and acidified with 500 mL 0.2%acetic acid, vortex mixed for 60 seconds, andcentrifuged at 3,000 · g for 3 minutes. The super-natant was removed by aspiration using a pipetteattached to a vacuum flask, and the remaining aque-ous layer was evaporated to dryness in vacuo. Theresidues were reconstituted with 200 mL HPLC water,and solution was injected via HPLC. The amount of

Figure 1.Study flowchart.


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MF present in a GCF sample was determined bycomparing the peak responses of the standard andthe sample of MF solution.

Statistical AnalysesPower analysis calculations were performed beforethe study was initiated. To achieve 90% power anddetect mean differences of the clinical parametersbetween groups, 25 sites in each group were required.Categorical variable (site-specific PI) was expressedas percentage and continuous variables (full-mouthPI, mSBI, PD, CAL, and IBD depth) as mean – SD.

Site-specific PI was compared by using the x2 testor a Fisher exact test when the expected frequencywas <5. Normality assumption was tested usingShapiro-Wilk W test. Between-treatment group com-parison was performed using analysis of variance andpost hoc Scheffe test, if continuous variable after anormal distribution. Statistical significance was de-fined as P <0.05. Statistical analysis was performedwith statistical software.¶¶

Table 1.

Site-Specific PI in the Placebo and Test Groups at Baseline, 3, and 6 Months

Baseline 3 Months 6 Months

Score Placebo 0.5% MF 1% MF 1.5% MF Placebo 0.5% MF 1% MF 1.5% MF Placebo 0.5% MF 1% MF 1.5% MF

0 0 0 0 0 22 21 22 22 21 20 19 20

1 14 14 15 16 4 6 5 7 5 7 8 9

2 9 10 9 10 0 0 0 0 0 0 0 0

3 3 3 2 3 0 0 0 0 0 0 0 0

P value* 0.983 0.913 0.943

* Chi-Square test.

Table 2.

Mean Values of Clinical Parameters at Each Visit

Parameter Placebo (mean – SD) 0.5% MF (mean – SD) 1% MF (mean – SD) 1.5% MF (mean – SD)

PIBaseline 1.87 – 0.28 1.86 – 0.26 1.90 – 0.26 1.89 – 0.253 Months 1.08 – 0.31 1.11 – 0.22 1.10 – 0.22 1.09 – 0.226 Months 0.73 – 0.21 0.69 – 0.13 0.68 – 0.11 0.70 – 0.12

mSBIBaseline 2.00 – 0.39 2.05 – 0.36 2.04 – 0.32 2.08 – 0.353 Months 1.54 – 0.35 1.14 – 0.32 1.11 – 0.29 1.13 – 0.316 Months 1.63 – 0.29 0.89 – 0.30 0.87 – 0.27 0.88 – 0.28

PD (mm)Baseline 8.03 – 1.10 8.00 – 0.79 8.13 – 0.94 8.16 – 0.753 Months 6.53 – 0.90 6.03 – 0.77 5.23 – 0.50 5.36 – 0.776 Months 6.27 – 0.87 5.03 – 0.67 4.13 – 0.73 4.36 – 0.81

CAL (mm)Baseline 6.27 – 0.79 6.40 – 0.86 6.43 – 0.86 6.30 – 0.793 Months 5.30 – 0.75 4.83 – 0.75 3.90 – 0.92 3.93 – 0.746 Months 4.93 – 0.64 4.16 – 0.59 2.60 – 0.72 2.70 – 0.75

IBD depth (mm)Baseline 4.92 – 0.57 4.89 – 0.50 4.91 – 0.50 4.85 – 0.526 Months 4.73 – 0.45 3.86 – 0.46 3.34 – 0.61 3.47 – 0.58

Measurements were not taken at 3 months for IBD depth.

¶¶ SPSS v.14, IBM, Chicago, IL.


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RESULTS

Thirty-seven of 41 patients (multiple sites per patient)completed the study (Fig. 1). Four patients failed toreport at follow-up and were excluded from analysis.All patients tolerated the drug well without any com-plications or adverse reactions. Soft tissues healedwithin normal limits, and no significant visual differ-ences were noted.

All the groups showed improvement in site-specificPI score and full-mouth PI score, but there was nostatistically significant difference in site-specific PIscore and full-mouth PI score between the groupsat any visit (Tables 1 through 3). This indicates thatboth groups maintained comparable levels of oralhygiene throughout the study.

mSBI in all the groups showed no difference atbaseline, but it was significantly decreased in all threetest groups (0.5%, 1%, and 1.5% MF) compared with

the placebo group at 3 and 6 months (P <0.05) (Tables2 and 3).

The clinical parameters PD and CAL also showed nodifference between both groups at baseline. However,all three MF groups showed significantly greater PDreduction and CAL gain at 3 and 6 months than theplacebo group at P <0.05. Also, 1% and 1.5% MFshowed significantly greater PD reduction and CALgain than 0.5% MF at 3 and 6 months (Tables 2, 4,and 5)

The radiographic parameter, IBD, showed stati-stically significant mean reduction at 6 months in allthree MF groups compared to the placebo group.However, 1% MF showed greater mean IBD reduc-tion at 6 months than 0.5% and 1.5% MF (Tables 2,4, and 5).

The MF groups presented with a significantly greatervertical defect fill (21.11% – 3.81%, 31.89% – 10.26%,

Table 3.

Intergroup Comparisons of Mean PI and mSBI at Each Visit

PI (P value) mSBI (P value)

Groups Baseline 3 Months 6 Months Baseline 3 Months 6 Months

Placebo versus 0.5% MF 0.999 0.980 0.856 0.965 <0.001* <0.001*

Placebo versus 1% MF 0.989 0.991 0.728 0.987 <0.001* <0.001*

Placebo versus 1.5% MF 0.998 0.999 0.920 0.851 <0.001* <0.001*

0.5% versus 1% MF 0.970 1.000 0.995 0.999 0.984 0.992

0.5% versus 1.5% MF 0.989 0.995 0.999 0.987 0.999 0.998

1% versus 1.5% MF 0.999 0.999 0.979 0.965 0.997 0.999

* P £0.05.

Table 4.

Mean Change From Baseline in PD, CAL, IBD Depth, and Percentage Bone Fill in thePlacebo and Test Groups at 3 and 6 Months

Parameter Placebo (mean – SD) 0.5% MF (mean – SD) 1% MF (mean – SD) 1.5% MF (mean – SD)

PD (mm)Baseline to 3 months 1.50 – 0.73 1.97 – 1.07 2.90 – 0.92 2.80 – 0.89Baseline to 6 months 1.77 – 0.77 2.97 – 0.93 4.00 – 1.05 3.80 – 1.03

CAL (mm)Baseline to 3 months 0.97 – 0.41 1.57 – 0.57 2.53 – 0.78 2.36 – 0.56Baseline to 6 months 1.33 – 0.66 2.23 – 0.73 3.83 – 0.95 3.60 – 0.81

IBD depth (mm)Baseline to 6 months 0.19 – 0.38 1.03 – 0.20 1.57 – 0.57 1.38 – 0.69

Percentage bone fillBaseline to 6 months 3.35 – 8.36 21.11 – 3.81 31.89 – 10.26 27.90 – 12.58

Measurements were not taken at 3 months for IBD depth or bone fill percentage.


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and 27.90% – 12.58%) with 0.5%, 1%, and 1.5% MF,respectively, than the placebo sites (3.35% – 8.36%)at 6 months (Tables 4 and 5).

MF in GCF peaked at 2 hours after application(Table 6). The drug was retained in the target com-partment for a long period, suggesting a controlledrelease of the drug until 4 weeks in 1% and 1.5% MF gel.

DISCUSSION

The current study has evaluated the clinical efficacy ofvarying concentrations of MF gel in adjunct to SRP forthe treatment of IBD in patients with CP and showedsignificant reduction in radiographic IBD depth andimprovement in clinical parameters compared toplacebo gel.

MF, first developed in 1957, is one of the mostcommonly used oral antihyperglycemic agents for thetreatment of type II diabetes mellitus.18 It is currentlyrecommended as first-line therapy in overweight orobese patients with this condition.6 However, it doesnot only effectively lowers blood glucose but alsoprotects bone tissue in patients with diabetes. Pre-vious experiments have been performed on bio-logic transport of MF in osteoblasts to verify thefeasibility of local drug delivery in vitro and foundthat the osteoblasts can uptake MF.19 MF wasfound to significantly decrease intracellular reactiveoxygen species and apoptosis and also had a directosteogenic effect on osteoblasts that could be partiallymediated via promotion of Runx2 and insulin-like

Table 5.

Intergroup Comparisons of Mean Change From Baseline in PD, CAL, IBD Depth, andPercentage Bone Fill at 3 and 6 Months

PD CAL IBD Depth % Bone Fill

Groups 3 Months 6 Months 3 Months 6 Months 6 Months 6 Months

Placebo versus 0.5% MF 0.273 <0.001* 0.002* <0.001* <0.001* <0.001*

Placebo versus 1% MF <0.001* <0.001* <0.001* <0.001* <0.001* <0.001*

Placebo versus 1.5% MF <0.001* <0.001* <0.001* <0.001* <0.001* <0.001*

0.5% versus 1% MF 0.002* 0.001* <0.001* <0.001* 0.001* <0.001*

0.5% versus 1.5% MF 0.007* 0.012* <0.001* <0.001* 0.065 0.053

1% versus 1.5% MF 0.980 0.882 0.757 0.732 0.536 0.435

* P £0.05. Measurements were not taken at 3 months for IBD depth or bone fill percentage.

Table 6.

MF Concentration (mean – SD) in GCF After Treatment

Concentration of MF (mg/mL)

Time 0.5% MF 1% MF 1.5% MF

Baseline 0.00 – 0.00 0.00 – 0.00 0.00 – 0.00

2 hours 8.38 – 0.19 10.26 – 0.03 10.84 – 0.08

4 hours 6.22 – 0.30 8.31 – 0.12 8.63 – 0.70

6 hours 5.03 – 0.11 7.24 – 0.08 7.46 – 0.23

Day 1 3.89 – 0.72 5.15 – 0.44 5.62 – 0.80

Day 2 2.74 – 0.33 3.28 – 0.28 3.46 – 0.51

Day 7 1.38 – 0.46 2.35 – 0.21 2.52 – 0.39

Day 14 0.24 – 0.03 1.08 – 0.67 1.11 – 0.26

Day 28 0.0 – 0.00 0.34 – 0.23 0.38 – 0.13

Day 56 0.00 – 0.00 (not detected) 0.00 – 0.00 (not detected) 0.00 – 0.00 (not detected)


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growth factor-1 expression.20 Thus, these possiblebone-sparing and bone-formative effects of MF maybe of considerable interest to the periodontist inmanaging periodontitis-induced alveolar bone loss.

In accordance with these previous studies, the re-sults of the current study demonstrate a decrease inPD, CAL, IBD depth, and increase in percentagebone fill for the MF-treated groups as an adjunctto SRP. Both 1% MF and 1.5% MF showed similarimprovement in clinical parameters, and the meanconcentrations in GCF were also similar. Thus, itcan be hypothesized that 1% MF gel provides theoptimum clinical benefit at the lowest concentration.However, additional studies using different vehiclesand concentrations of MF should be performed toconfirm the observations of our study.

The possible errors in measuring the IBD fill onradiographs, such as those attributable to exposuresettings, geometric error (e.g., radiographic tech-niques), and the development of films, were mini-mized. The mean concentration of MF at all observedperiods (except 8 weeks), as estimated by reverse-phase HPLC, provided sufficient anti-inflammatoryactivity and fulfilled the conditions for a controlled-release device. Maintenance of this concentration ofthe drug locally for a long duration may have beenresponsible for the additional improvement in PD,CAL, and bone regeneration (IBD fill) in the 1%and 1.5% MF groups compared to the 0.5% MF andplacebo groups.

The current study has considered a technique ofdirect subgingival injection for delivering MF intopockets of patients with CP because the local drugdelivery systems offer the advantages of high con-centrations at the target site with reduced dosage,fewer applications, and high patient acceptability.21

Compared to a systemic regimen, local delivery mayoffer important benefits in terms of adverse reactionsand patient compliance.22

CONCLUSIONS

The results of the present study show that local de-livery of varying concentrations of MF gel into peri-odontal pockets stimulated a significant increase inthe PD reduction and CAL gain and improved IBDdepth reduction compared to placebo gel in adjunctto SRP. The 1% MF gel along with SRP was found toprovide maximum improvement in clinical and ra-diologic parameters. Thus bone-formative effects ofthe common oral antihyperglycemic agent MF canprovide a new direction in the field of periodontal re-generation. However, long-term, multicenter, ran-domized, controlled clinical trials will be required toknow its clinical, histologic, and radiographic effecton bone healing.

ACKNOWLEDGMENTS

The authors thank Aurobindo Pharma, Hyderabad,Andhra Pradesh, India, for providing the gift sampleof MF. They also thank Professor Shivanand, Prin-cipal, Al-Ameen College of Pharmacy, Bangalore,India, andMr. Nagraj Patro (PhD student), Departmentof Pharmaceutics, Al-Ameen College of Pharmacy,for helping us in preparingMFand placebo gel. The au-thors report no conflicts of interest related to this study.

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Correspondence: Dr. A. R. Pradeep, Department of Periodon-tics, Government Dental College and Research Institute,Bangalore 560002, India. Fax: 08026703176; e-mail:[email protected].

Submitted January 12, 2012; accepted for publicationMarch 12, 2012.


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