A clinicoradiographic assessment of 1% metformin gel with platelet-rich fibrin in the treatment of mandibular grade II furcation defects.

BACKGROUND: Management of furcation defects is challenging, and constantly newer therapeutic strategies are evolving. Platelet-rich fibrin (PRF) is successfully used alone and in combination with various agents in the furcation defects. Lately, metformin (MF), a second generation biguanide has gained popularity owing to its osteogenic potential. AIMS AND
OBJECTIVES: The aim of the present study was to evaluate the clinical and radiographic effectiveness of open flap debridement (OFD) and PRF when compared to OFD + PRF + 1% MF gel in the management of mandibular Grade II furcation defects.
MATERIALS AND METHODS: Thirty mandibular grade II furcation defects were stratified into two groups; in one group OFD and PRF is used, and the other group had an additional MF gel with PRF in OFD. Clinical parameters such as plaque index, modified sulcus bleeding index, probing pocket depth (PD), relative vertical attachment level (RVAL), and relative horizontal attachment level (RHAL) were recorded at baseline and at 6 months. Radiovisiography and ImageJ software were used to evaluate the intrabony defect depth.
RESULTS: The OFD + PRF + MF group showed significantly higher probing PD reduction, RVAL and RHAL gain than the OFD + PRF group.
CONCLUSIONS: PRF when combined with a potential osteogenic agent like MF can provide a better therapeutic benefit to a furcation involved tooth.

INTRODUCTION

Periodontal diseases encompass a set of inflammatory conditions resulting in the obliteration of the supporting tissues of the teeth, particularly bone, through osteoclastic resorption.[1] A clinician's vision has always been on efforts to regenerate lost alveolar bone. This holds true, especially in furcation areas where the ease of access to instrumentation has always been a challenge.[2] The presence of proximal deep furcation defects may not only affect the response to therapy of an affected tooth adversely but also the prognosis of adjacent teeth.[345]

To overcome these challenges, newer therapeutic modalities such as Emdogain, PRP, introduction of growth factors, and bone morphogenetic proteins have been initiated.[6789] Lately, metformin (MF), an antidiabetic agent, is successfully used as a local drug delivery agent in chronic periodontitis patients.[10] Literature has suggested that MF possesses osteogenic potential and it is also established that MF induces growth of osteoblast precursor cells.[10] Histological studies have supported the role of MF as an anti-inflammatory agent, and thus, it is known to hinder bone resorption in a periodontitis model.[10] A significant improvement in the clinical parameters has been reported when MF is used in conjunction with SRP in chronic periodontitis cases.[10]

The aim of the present study was to assess the clinical as well as radiographic effectiveness of open flap debridement (OFD) + platelet-rich fibrin (PRF) and OFD + PRF + 1% MF gel in the management of mandibular Grade II furcation defects.

MATERIALS AND METHODS

This clinicoradiographic single center, longitudinal, double-blind study was performed for a duration of 6 months. A total of 30 sites in 22 patients having Grade II furcation involved mandibular molars were chosen from the outpatient department of Periodontology. The selected sites were stratified arbitrarily with the toss of coin into two groups. The distribution of study participants, as well as the study design, is depicted in Figure 1.

Figure 1

Study design; n - Number of participants

Group A: Test group consisted of 15 buccal grade II furcation defects that were managed by OFD followed by PRF and 1% MF gel

Group B: Control group consisted of 15 buccal grade II furcation defects that were managed by OFD followed by PRF only.

After getting the approval from the institutional ethical board, the participants were verbally informed about the study protocol and written informed consent was received. Diagnosis of chronic periodontitis was made according to the American Academy of Periodontology, 1999 World Workshop Consensus.[11] The set criteria for inclusion in the study were:

Buccal Grade II furcation defect in mandibular molars which were endodontically vital[12]

Asymptomatic mandibular first and second molars with a radiolucency in the furcation area on the radiovisiography (RVG)

Probing pocket depth (PD) >5 mm and horizontal PD >3 mm after phase 1 therapy.[1314]

The exclusion criteria for the study were:

Diabetic patients, patients with cardiac disorders or bleeding disorders, immunocompromised (e.g., HIV individuals) individuals, and patients on long-term medications such as corticosteroids or calcium channel blockers which may affect the bone metabolism

Patients with reported allergies to medications

Pregnant or lactating females

Patients with a habit of tobacco chewing/smoking

Individuals with poor oral hygiene

Teeth with interproximal intrabony defects and gingival recession

Mobility of tooth Grade II or teeth with furcation caries was also excluded.

The enrolled patients signed informed consent form in English as well as in Hindi language to willingly participate in the research. Comprehensive medical and dental histories were taken to assess for any contraindications. The clinical parameters incorporated site-specific plaque index (PI),[15] modified sulcus bleeding index (mSBI),[16] PD from the gingival margin, relative vertical attachment level (RVAL), and relative horizontal attachment level (RHAL) from the apical level of custom-made acrylic stents with grooves to ensure a reproducible placement of a periodontal probe (PCP-UNC 15, Hu Friedy® for vertical measurement) and Naber's probe (Hu Friedy® PQ2N6-for horizontal measurement). All the clinical parameters were examined at baseline and 6 months postoperatively.

For evaluation of intrabony defect (IBD) depth, distance from the furcation fornix to the base of the defect was taken into consideration. RVG images were obtained preoperatively and 6-month postoperatively. Radiolucency at the furcation site was measured from the furcation fornix, in millimeters.[17] Image J software (1.50i, National Institutes of Health, USA) was used to measure the bone defect depth.

Presurgical phase included phase I therapy after which sites were randomly chosen for test and control group with the toss of a coin.

Surgical phase

The PRF was formed as per the procedure stated by Choukroun et al.[18] Just before the surgical procedure, intravenous blood (by venipuncturing the antecubital vein) was collected in three, 10-ml sterilized test tubes. No anticoagulant was added to the tubes and instantly centrifuged in centrifugation machine (REMI, Mumbai) at 3000 RPM for 10 min. This ensured the formation of structured fibrin clot in the center of the tube, just in the middle of the red corpuscles at the base and acellular plasma (platelet-poor plasma [PPP]) at the top. PRF was separated from RBCs using sterile tweezers and scissors just after the removal of PPP. Then, it was transferred onto sterile gauze compress so as to squeeze out the serum out of a stable PRF membrane. This membrane thus formed is easy to handle and be manipulated by the operator. PRF, thus prepared, was used in two ways in both groups, one to fill the defect (with or without 1% MF gel) and second as a protective barrier membrane over the defect space.[19]

Preparation of 1% metformin gel

MF gel was prepared as described by Mohapatra et al.[20] The necessary ingredients needed for the gel preparation were weighed precisely. Initially, a dry gellan gum powder and distilled water were mixed with a magnetic stirrer at 95°C for a period of 20 min to facilitate the formation of hydrous gellan gum. The temperature was maintained at ≥80°C, and mannitol (required amount) was added to the solution formed. Subsequent to this, MF (weighed quantity) was incorporated in addition to the citric acid, sucralose and preservatives such as propylparaben and methylparaben. It is important to continuously stir the mixture all through the procedure. To this mix, the required amount of liquefied sodium citrate was incorporated. This blend produced a gel once; it was cooled at around 20°C–25°C. Hence, the concentration of final MF gel was adjusted to ~1%.

Before surgery, patients rinsed with 0.12% chlorhexidine digluconate (Hexidine® ICPA). Subsequent to administering local anesthesia, intracrevicular incisions were given at buccal and lingual surfaces, and mucoperiosteal flaps were reflected [Figure 2].[13] Thorough defect debridement was done followed by root planing with area-specific curettes (Gracey curettes Hu-friedy®) and furcation curettes (Quetin SQBL 16 Hu-friedy®). The prepared gel of 1% MF was mixed with PRF and placed into the furcation defect following OFD in group A [Figure 3], whereas in group B, PRF alone was placed into the furcation defect. The furcation defects of both the groups were further covered by a PRF membrane to provide protection and space [Figure 4]. The mucoperiosteal flaps were repositioned and sutured with 3-0 non-absorbable silk surgical sutures [Figure 5]. The treated area was covered by means of periodontal dressing [Figure 6]. Postoperative instructions were given. The prescribed medications were 500 mg amoxicillin, 400 mg metronidazole and 400 mg ibuprofen t. i. d all for 7 days. Patients were asked to rinse chlorhexidine digluconate rinses (0.12%) (Hexidine® ICPA), for the next 15 days twice daily. Suture removal was performed 10 days postsurgery. The treated areas were then gently cleansed, and participants were instructed to resume brushing in the operated area with a soft toothbrush. Soft and hard tissue evaluations were done 6 months post-surgery. For hard tissue reevaluation, second RVG images of the same study site were taken, and furcation bone defect measurements were reevaluated [Figures 7 and 8].

Figure 2

Reflection of mucoperiosteal flap and debridement

Figure 3

Placement of platelet-rich fibrin and 1% metformin gel mixture

Figure 4

Application of platelet-rich fibrin membrane to cover the defects

Figure 5

Repositioning and suturing with interdental sutures

Figure 6

Application of periodontal dressing

Figure 7

Preoperative radiovisiography for intrabony defect measurement

Figure 8

Six-month postoperative radiovisiography depicting intrabony defect fill

Radiographic assessment of intrabony defects

The depth of IBD was evaluated at baseline and 6 months with the help of an image analyzer (Image J®) IBD was measured on the radiograph by computing the vertical distance from the crest of the alveolar bone to the base of the defect. Standardized radiographs were taken using the paralleling technique and holders so as to obtain films as reproducible as possible. All the radiographic images were evaluated in a single reference centre by the masked evaluator.

Statistical analysis

The statistical analysis for the periodontal parameters was done using a “Paired t-test” (intragroup) and one-way ANOVA (intergroup) for comparative evaluation at two different time intervals for clinical and radiographic parameters. For all the tests, P ≤ 0.05 was considered statistically significant.

RESULTS

The characteristics of the study groups are represented in Table 1. All the patients completed the study. There were no statistical differences in the mean age and sex among the test and control groups. No undesirable reactions related to the treatment procedure were noted among patients. Satisfactory wound healing was observed at all the sites involved in the study. Results of the study are expressed in Table 2.

Table 1

Characteristics of the study population

Table 2

Clinical and radiographic parameters in study groups at baseline and 6 months

Primary outcome measures were RVAL, RHAL, and IBD depth, whereas secondary outcome measures were PI, mSBI, and PD.

A statistically significant reduction in both PI and mSBI was observed at 6 months from baseline in both the study groups. This indicates uniformity in oral hygiene maintenance by all the study participants.

A highly significant improvement in PD was observed in both the study groups at 6 months from baseline. On comparing intergroup data, Group A showed highly significant reduction in PD (P = 0.01) compared to Group B.

The mean score of RVAL at 6 months for Group A showed no significant difference compared to the Group B score. However, the mean scores of RHAL and IBD at 6 months showed significant improvement compared to the baseline scores (P ≤ 0.05) in both the study groups. At 6 months, the mean score of RHAL for Group A showed statistically significant improvement compared to the scores of Group B. On the other hand, at 6 months, the mean score of IBD, 3.68 ± 0.97 for Group A showed no significant improvement over Group B (3.42 ± 0.51) (P > 0.05). None of the treated defects progressed to degree III.

DISCUSSION

The present study investigated the effectiveness of PRF when combined with MF in the management of furcation defects. At baseline all the values were almost identical and statistically nonsignificant. At 6 months, the mean score of PI for Group A showed a significant improvement over Group B, (P ≤ 0.05). The closely monitored regimen of maintenance was identical in both the study participants. The difference in the results at 6 months can clearly be attributed to the complete or partial closure of the furcations.[132122] This improvement is in accordance with the studies of Caffesse et al. and Pradeep et al.[1322] At 6 months, the mean score of mSBI showed significant improvement from baseline scores in both the study groups. Similar observations were recorded by Thorat et al. and Pradeep et al.[1323]

Probing depth is not only a sought-after result of periodontal regeneration procedure but also an important factor for patients oral self-care strategy. At 6 months, significant reduction in PD was observed in both the study groups. On intergroup comparisons a highly significant value was obtained favoring Group A (P ≤ 0.01). The observations indicate significant gain in clinical attachment level which is a consequence of improved tissue healing following surgical periodontal treatment.[6132425]

Similarly, the mean scores of RVAL of both the groups showed significant improvement at 6 months from baseline. However, intergroup comparisons yielded nonsignificant results. Our findings are in agreement with the findings of Bowers et al., Anderegg et al., Selvig et al., Machtei et al., and Black et al.[2627282930]

A significant improvement in intergroup comparisons of RHAL at baseline and 6 months was also found. Presurgical RHAL has confirmed a contrary association with furcation closure, increase in horizontal probing depth were more or less associated with diminished percentage of sites demonstrating complete clinical closure.[26] This was further proven by the results of our study. Complete furcation closure was obtained in 90% of early furcation lesions (≤4 mm).[26] We attained almost matching results where Group A containing MF was significantly better compared to Group B in furcation closure. This can be attributed to MF because it is a known activator of proliferation and differentiation of local progenitor cells leading to the formation of new bone matrix. Also, MF significantly reduces the intracellular reactive oxygen species and apoptosis of local progenitor cells which improve the production of type I collagen leading to enhanced healing.[10] Thus, generous bone fill was obtained in Grade II furcations in the Group A. A 6 months evaluation period in our study was based on several studies which revealed that dimensional changes of periodontal tissues ensuing from surgical healing sometimes continue to occur up to 6 months.[3132]

The IBD depths at 6 months did not differ much in both the groups. The reason for this seems to be because of slow release of growth factors such as platelet-derived growth factor, transforming growth factor beta 1 in the case of PRF, and insulin-like growth factor-1 expression in the case of MF. The release of all these factors has been found to be timebound in different studies. Furthermore, a study by Borges et al. revealed that 80 weeks of MF treatment induces very modest increase in bone mineral density, thus these possible bone sparing and bone formative effects of MF may be linked to the passage of time.[33] Studies indicate that 1% MF worked best and superior to 0.5% and 1.5% concentrations 34 and was retained in the target compartment suggesting a sustained release of drug until 4 weeks, when used as intrapocket gel.[21] Thus, it seems the growth factors obtained from both PRF as well as MF have a wash off period limiting the accuracy over the 6 months period of the study.[35] Another factor to be taken into consideration is that, highest probability of clinical furcation closure and IBD reduction was detected in early class II defects, and in general, the results were proportionate to the extent of furcation involvement – the earlier, less severe the defect, the greater the likelihood of achieving complete clinical furcation closure. Furthermore, anatomical challenges such as short-root trunks architecture of furcation entrance, root divergence, root surface irregularities and curvatures, interradicular root surfaces, and root concavities all affect the regeneration of furcation defects in mandibular molars predominantly first molars possibly affecting the IBD reduction.[26]

In the present study, the efficacy of PRF with MF was assessed for 6 months duration. The evaluative period could have been longer to elucidate the role of MF in inducing bone formation. Latest advances in radiographic techniques like cone-beam computed tomography could have been utilized to assess furcation defects.

CONCLUSIONS

The observations of our study revealed that MF may exhibit a beneficial effect on the alveolar bone by increasing osteoblast differentiation. Although we are unsure about definitive and conclusive remarks regarding the effect of MF, the present findings appear to be meaningful with regards to the beneficial effects of MF on bone tissues in Grade II furcation defects. However, more longitudinal, multicentric, randomized controlled clinical and interventional trials will need to be conducted to know its clinicohistologic and radiographic effects on the healing of the bone, thereby confirming the findings of our study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.