Comparative evaluation of open flap debridement alone and in combination with anorganic bone matrix/cell-binding peptide in the treatment of human infrabony defects: A randomized clinical trial.

BACKGROUND: The synthetic anorganic bone matrix/cell-binding peptide (ABM/P-15) has displayed an increased fibroblast migration and attachment with bone graft material, thus enhancing periodontal regeneration. The objective of the present study was to evaluate and to correlate the efficacy of open flap debridement (OFD) with and without ABM/P-15 in the treatment of human infrabony periodontal defects.
MATERIALS AND METHODS: A total of 20 chronic periodontitis patients with equal number infrabony defects were randomly selected and assigned into two groups depending on the treatment received: Control group (treated with OFD) and Test group (treated with OFD + ABM/P-15). Clinical parameters recorded included plaque index, gingival index, probing pocket depth (PPD), clinical attachment level (CAL), gingival recession, and radiographic defect depth (RDD) which were evaluated at baseline and 6 months postsurgically.
RESULTS: When compared to baseline, both the treatment groups demonstrated improvements in the clinical parameters at 6 months. Test group exhibited a mean PPD reduction of 4.15 ± 1.04 mm, CAL gain of 3.10 ± 1.42 mm, and reduction in RDD of 1.90 ± 0.72 mm postoperatively at 6 months. In contrast to Control group, the Test group showed greater reduction in PPD (P < 0.05) which was statistically significant, greater CAL gain and greater mean RDD reduction (P < 0.001) which was highly significant.
CONCLUSION: In the surgical management of periodontal infrabony defects, Test group elicited in statistically significant PPD reduction, CAL gain, and better infrabony defect fill at 6 months' postoperatively.

INTRODUCTION

Periodontal diseases are a cluster of chronic inflammatory infectious conditions affecting the periodontium causing alveolar bone loss. The ideal object of periodontal therapy is to confer a dentition that commissions in health and comfort of the patient for an entire lifetime.[1] To achieve this goal, regenerative periodontal therapy is carried out which aims at regeneration of lost periodontium resulting in embedding of newly established periodontal ligament fibers in newly organized cementum and alveolar bone, thereby recreating the junctional epithelium at cementoenamel junction.

As reported by the American Academy of Periodontology, periodontal regeneration has been described as the replication of a lost or injured part to duplicate the structure, function, and organization of the periodontium.[2] In the literature, two main treatment modalities, bone grafting,[3] and guided tissue regeneration[4] have been proposed, clinically evaluated and are known to advance regeneration in human infrabony defects. Different bone graft materials, their combinations and their synthetic replacements, have been used and are suggested to achieve desired therapeutic outcome. In vitro investigations confirm that anorganic bovine bone matrix enhances cell attachment, stimulation of periodontal ligament fibroblast, and proliferation of osteoblastic cells.[5]

A recently introduced peptide-enhanced bone augmentation material for periodontal regenerative therapy includes an amalgamation of natural anorganic bovine-derived matrix with an artificial cell-binding peptide (ABM/P-15). The peptide, P-15, is a synthetic tissue engineered analog representing small fraction (0.5%) of Type I collagen and has manifested an increase fibroblast migration and attachment to bone graft material, thus enhancing periodontal regeneration.[6] A histopathologic case report evaluating the combination of ABM/P-15 in conjunction with periodontal surgery, in human infrabony defects exhibited true regeneration of the periodontium, comprising of the cementum, periodontal ligament, and alveolar bone, in periodontally diseased sites.[7] The rationale behind using ABM/P-15 is that the inorganic component of ABM; composed of calcium phosphate replicates the lost natural anatomic constitution of autogenous bone necessary for cellular invasion. The organic component represented by P-15, repeats the cell-binding domain of Type I collagen, and modulates cell bonding, migrations, multiplication, and differentiation.[8]

Very few clinical and animal trials have been conducted pertaining to the use of ABM/P-15 as bone augmentation material. The preliminary studies revealed encouraging results pertaining to the regeneration of the periodontal structures. With view of the above facts in mind, it was felt necessary to further evaluate this material in the treatment of human infrabony defects. Hence, the present study was planned as a controlled clinical trial to evaluate and to compare the effectiveness of ABM/P-15 with open flap debridement (OFD) in the treatment of human infrabony defects clinically and radiographically. The primary outcome of the study was percentage fill of the radiographic infrabony component of the defect, while the secondary outcome of the study was changed in probing pocket depth (PPD) and clinical attachment level (CAL) gain at 6 months.

MATERIALS AND METHODS

The present randomized-split-mouth study comprised of a total of 20 patients in age range 30–45 years affected with advanced chronic periodontitis and was initiated after approval from Institutional Ethics Committee with protocol number: VSPM/DCRC/IEC/08. All the surgical procedures were carried out after obtaining the written informed consent.

Power analysis suggested that 20 patients with power of 90% would provide sufficient data for appropriate statistical analysis with an alpha/beta = 1 for clinically meaningful changes in clinical probing attachment level and percent defect fill.

Patient selection

All the patients included in the study exhibited one pair of bilateral deep interproximal, infrabony periodontal defects with a PPD of ≥5 mm, and radiographic evidence of angular bone loss of at least ≥3 mm at baseline. Among these defects, there were eight 2-wall deep defects in Control group while for the Test group, there were eleven 2-wall deep defects. Patients with previous history of periodontal treatment in the past 6 months, history of known systemic diseases, or pregnant/lactating women were excluded from the study. All the patients underwent preliminary preparation including supra and subgingival scaling, root planing, and occlusal adjustments 4–6 weeks before surgery.

The consort flowchart [Figure 1] illustrates the accessibility, selection, randomization, and surgical intervention of the study participants.

Figure 1

Consort flowchart

Clinical parameters

Clinical parameters were measured and noted by a calibrated examiner (PM) using custom-made occlusal acrylic stents to standardize the probe recordings with UNC15 periodontal probe (UNC15 periodontal probe, Hu-Friedy, Chicago, IL, USA) [Figure 2a and e]. The clinical parameters recorded included: plaque index (PI),[9] gingival index (GI),[10] PPD, CAL, and gingival recession (GR).

Figure 2

Surgical protocol for Test group (ABM/P-15): (a) Baseline clinical measurement. (b) Full-thickness flap elevated. (c) ABM/P-15 graft placement following thorough debridement and presuturing. (d) Flap repositioning to preoperative level. (e) Postoperative clinical measurement of the treated area after 6 months. OFD – Open flap debridement; RDD – Radiographic defect depth; ABM/P-15 – Anorganic bone matrix/cell-binding peptide

The radiographic parameter recorded at baseline (Figuers 3a and 4a) included radiographic defect depth (RDD) measured on an intraoral periapical radiograph (IOPA) obtained by long-cone paralleling technique which involved the assistance of film-holding device (XCP Rinn Dentsply), utilizing a millimeter grid mount (Dentech Corporation, Japan).

Figure 3

Radiographic measurement following treatment in control (OFD) group: (a) OFD baseline RDD. (b) OFD 6 months postoperative, radiographic defect depth. OFD – Open flap debridement; RDD – Radiographic defect depth

Figure 4

Radiographic measurement following treatment in test (OFD + ABM/P-15) group: (a) ABM/P-15 baseline RDD. (b) ABM/P-15, 6 months postoperative radiographic defect depth. OFD – Open flap debridement; RDD – Radiographic defect depth; ABM/P-15 – Anorganic bone matrix/cell-binding peptide

Clinical procedure

The selected sites were randomly divided by flip of coin into test (OFD + ABM/P-15) and Control (OFD alone) group. Under local anesthesia, full-thickness mucoperiosteal flap was reflected to gain access for the defect debridement [Figure 2b]. Baseline hard-tissue measurement, vertical osseous probing depth (VOPD) for each site was recorded at the time of surgery from the alveolar crest (AC) to base of osseous defect (BD). The ABM/P-15 bone graft material (Ceramed Lakewood, Colorado 80228 USA) was hydrated with five drops of saline using a 10 cc syringe, for 5–10 min in a dappen dish, before placement of the graft material as per manufacturer's instruction. The graft material was placed into the defect and condensed using plastic filling instrument till the level of the alveolar crest [Figure 2c]. Flaps were approximated using interrupted sutures followed by the interproximal sutures next to the defect site [Figure 2d]. Control sites were sutured similarly without placement of the graft. A periodontal dressing was placed. Patients were prescribed postsurgical instructions, and medications were prescribed including antibiotics and anti-inflammatory drugs. Sutures were removed after 7 days.

Postsurgical evaluation

The patients were evaluated clinically and radiographically [Figures 3b and 4b] at 6 months’ intervals. During the first 2 months of postsurgical follow-up, the patients were reviewed every 2 weeks and after 2 months, patients were recalled once every month for oral hygiene maintenance.

Statistical analysis

The data were analyzed using Statistical Package for Social Science (SPSS 14, IBM, Armonk, NY, United States of America). All the clinical parameters calculated were represented as mean ± standard deviation. P value <0.05 was considered statistically significant. All the clinical parameters recorded were subjected to the following statistical analysis:

For intragroup variations paired t-test

For intergroup variations unpaired t-test.

RESULTS

All the selected patients were assessed for 6 months’ follow-up without any dropout. Wound healing was uneventful with no signs of complication or infection in both the groups. During the study observation period, all patients exhibited satisfactory oral hygiene. Table 1 illustrates the mean PI and GI for both groups.

Table 1

Plaque and gingival index (mean values±standard deviation) at baseline and 6 months

Table 2 summarizes the clinical and radiographic parameters for both the groups at baseline. The baseline values of all parameters evaluated were similar, and no significant differences were observed between them. This was indicative that the randomization process was effectively adhered to. The mean VOPD was 4.30 ± 1.52 mm for Test group and 4.05 ± 1.39 mm for Control group. There was no significant difference in the RDD parameter between the two groups.

Table 2

Measurements (mean values±standard deviation) at baseline - intergroup comparison

The Test group exhibited a mean PPD reduction of 4.15 ± 1.04 mm (P < 0.001), and a gain in the mean CAL of 3.10 ± 1.71 mm (P < 0.001) at 6 months’ postoperatively. The Control group exhibited a mean PPD reduction of 3.25 ± 0.63 mm (P < 0.001), a mean CAL gain of 2.60 ± 1.46 mm (P < 0.001). The sites treated in Test group showed statistically higher PPD reductions when compared to Control group (P < 0.05). There was a greater increase in CAL gain at 6 months for Test group compared to Control group; however, the difference was not statistically significant. GR at 6 months increased significantly in both groups compared with baseline, but without any significant difference between the groups. At 6 months, the mean reduction in RDD observed in the Test group (1.90 ± 0.72 mm) compared with Control (0.63 ± 0.53 mm) was statistically highly significant and in favour of Test group (P < 0.001) as depicted in Tables 3 and 4.

Table 3

Measurements (mean value±standard deviation) at baseline and 6 months - intragroup comparison

Table 4

Measurements (mean values±standard deviation) at 6 months - inter-group comparison

DISCUSSION

The present study performed from January 2017 to February 2018 with a six months’ observation period evaluated the efficacy of ABM/P-15 in the treatment of human infrabony periodontal defects. Clinically, no signs of undesirable immune response were detected in the ABM/P-15 group indicating the biocompatibility of the material used. These findings were similar to the findings of Cohen et al.[11] Six months’ time may be believed to be too short to fully access the outcome of periodontal therapy. Changes in clinical parameters as evaluated by Yukna et al. from baseline to 3 years, baseline to reentry (6 months) and reentry to 3 years was suggestive of the fact that the major clinical changes were essentially obtained primarily achieved at the time of reentry, with no further alterations from reentry to 3 years.[12] These observations are also identical to those reported by Pandit et al., who found no significant intragroup change in defect fill between 6 and 12 months, indicating that the defect had been filled to an optimum level by 6 months.[3]

The present study depicted no significant difference in the mean baseline values between both the groups. The defects included in the study had an infrabony component ≥3 mm deep, with 1-wall, 2-wall, wide 3-wall and/or combination type of bone loss. Narrow 3-wall defects were not included due to their apparently high rate of natural repair. The study conducted by Kher et al. exhibited that the regenerative capacity of the noncontained one-to-two wall component may be supplemented with regenerative therapy.[4] This was the reason behind including defects which were noncontained in the trial so that the true potential of the material can be evaluated.

Test group in the present study showed significant reduction in PPD at 6 months. Healing of the infrabony defects in Control group can be attributed to repair resulting in the development of a long junctional epithelium continuing almost to the bottom of the intraosseous defects. The formation of a long junctional epithelium has been confirmed in human block biopsies following OFD of infrabony pockets.[13] In the present study, there was a mean reduction of 4.15 ± 1.04 mm in PPD in the Test group. This finding is in accordance with studies conducted by Yukna et al.,[121415] who found a significant reduction in PPD with ABM/P-15. Pradeep et al. demonstrated mean PPD reduction of 4.50 ± 0.76 mm in the ABM/P-15+ autologous PRP group compared to 3.5 ± 0.65 mm in the autologous PRP group alone and the difference was statistically significant.[16] The differences can be attributed to the difference in treatment protocol, healing potential of the study individuals, and the differing geometry of the defects included in the respective studies. The clinical trials with various alloplastic bone grafts also have shown a significant reduction in PPD when compared to OFD.[1718]

In the present study, the mean gain in CAL was 3.10 ± 1.71 mm and 2.60 ± 1.46 mm in the Test and Control group at 6 months, respectively. The comparison between the groups at 6 months was found to be statistically insignificant but in favor of Test group, indicating that both the treatment modalities showed increased gain in CAL. Barros et al. in a case series demonstrated a significant reduction in PPD and significant gain in three relative CAL and suggested that the ABM/P-15 “flow,” combining the characteristics of the ABM as an inert scaffold with the cell-binding activity of the P-15, contributed to the clinical success.[19] In addition, the clinical trials with various synthetic alloplastic bone grafts have shown a significant gain in CAL when compared to OFD.[18]

Both the groups demonstrated significantly greater gingival recession at 6 months. However, the difference between the groups was not significant. This is in confirmation with the study by Nazareth and Cury, who found no added benefits in CAL gain and GR reduction in the ABM/P-15+ CPF (coronally positioned flap) compared to CPF alone in Class I gingival recession.[20] In contrast, Eto et al. reported a significant reduction in the gingival recession of 0.9 mm in the ABM/P-15 group in the treatment of Class II furcation defect. This could be explained by the fact that ABM/P-15 possess molecular characteristics that enhance cell attachment and proliferation that may have augmented root coverage.[21]

The change in RDD was considerable for both the groups at 6 months. However, the Test group displayed highly significant resolution of defect depth. The results are in correlation with studies by Yukna et al.[121415] and Pradeep et al.[16] The resolution of osseous defects is attributed to the obvious defect fill by the bone in the Test sites. The results are in accordance with studies in the literature using various autografts, allografts, and xenografts which have shown a significant bone fill in human intrabony defects when compared to open flap debridement.[341718]

The results of our study indicate that at 6 months interval, the evaluation of both the groups yielded similar results with regards to soft-tissue parameters, whereas when compared radiographically, the Test group showed statistically better results than the Control group. The explanation to this lies in the nature of the wound healing which occurs in the individual groups. In the Control group, the healing is expected by means of formation of long junctional epithelium, which definitely will yield improvements in soft-tissue measurements, whilst in case of the Test group P-15-coated ABM surfaces replicate the role of native collagen matrix in wound repair; and deposition of collagenous matrix is one of the components of repair in tissues. The P-15 peptide enhances the gene expression for alkaline phosphatase, BMP-2 and BMP-7, the osteogenic factors known to stimulate osteoblastic activity and promote matrix mineralization. Apart from the direct influence of P-15 on BMP expression, P-15 peptide may also augment the effects of osteogenic factors to activate osteoblastic differentiation.[6] This type of wound healing is expected to give rise to regeneration of the periodontal tissues. Hence, the soft-tissue parameters were somewhat similar to the Control group. However, the literature also suggests that better clinical and radiographic results with combination therapy with regenerative materials when compared to monotherapy or OFD.[22]

A previous literature search revealed that there is 25%–35% of defect fill following surgical debridement of human periodontal infrabony defects and adjunctive use of bone replacement graft enhanced it to 60%–70% independent of material used.[14] In the present study, a defect fill of 50.06% and 16.73% was obtained in the Test group and Control group, respectively, although the results were comparable; however, the percentage gain was less which could be attributed to several reasons as follows: (a) use of conventional radiographs for evaluation, as they are two-dimensional representations of the 3D periodontal hard tissues and tend to underestimate the true amount of bone present or lost; (b) Variations in the contrast and density caused by inefficient film processing may prevent the exact determination of osseous changes by the investigator.

There are, however, a few limitations of the present study such as the defect morphology has not been classified based on remaining bone walls; conventional radiograph was used for radiographic evaluation and the lack of histological assessment.

CONCLUSION

The combination of ABM/P-15 has proven to be a promising material for periodontal regeneration. While ABM serves as bone filling material, the cell-binding domain of P-15 enhances cell proliferation and migration, which is evident clinically and radiographically. The bone fill achieved in a short time frame by ABM/P-15 is highly encouraging for its use as bone augmentation material in periodontal and implant dentistry.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.