Evaluation of bioactive glass and demineralized freeze dried bone allograft in the treatment of periodontal intraosseous defects: A comparative clinico-radiographic study.

AIM: The purpose of this study was to evaluate the efficacy of demineralized freeze dried bone allograft (DFDBA) and bioactive glass by clinically and radiographically in periodontal intrabony defects for a period of 12 months.
MATERIALS AND METHODS: Ten systemically healthy patients diagnosed with chronic periodontitis, with radiographic evidence of at least a pair of contralateral vertical osseous defects were included in this study. Defect on one-side is treated with DFDBA and the other side with bioactive glass. Clinical and radiographic measurements were made at baseline 6 month and 12 month after the surgery.
RESULTS: Compared to baseline, the 12 month results indicated that both treatment modalities resulted in significant changes in all clinical parameters (gingival index, probing depth, clinical attachment level (CAL) and radiographic parameters (bone fill); P < 0.001*). However, sites treated with DFDBA exhibited statistically significantly more changes compared to the bioactive glass in probing depth reduction (2.5 ± 0.1 mm vs. 1.8 ± 0.1 mm) CAL gain 2.4 ± 0.1 mm versus 1.7 ± 0.2 mm; (P < 0.001*). At 12 months, sites treated with bioactive glass exhibited 56.99% bone fill and 64.76% bone fill for DFDBA sites, which is statistically significant (P < 0.05*).
CONCLUSION: After 12 months, there was a significant difference between the two materials with sites grafted with DFDBA showing better reduction in probing pocket depth, gain in CAL and a greater percentage of bone fill when compared to that of bioactive glass.

INTRODUCTION

The rationale of periodontal therapy is mainly indicated not only at inflammation control but also reduction of periodontal pockets and regeneration of alveolar bone, cementum and periodontal ligament.[1] Periodontal regeneration is defined as the reproduction or reconstitution of the lost or injured part so that form and function of lost structures are restored (glossary of periodontal terms AAP 1992). Bone replacement grafts (BRGs) have been shown to produce greater clinical bone defect fill than flap debridement alone. Various BRGs i.e., autografts, allografts, xenografts and alloplastic grafts have been introduced in the last two decades in an attempt to regain the lost attachment apparatus.[2345] These grafts contribute to new bone formation through osteogenic, osteoconductive or osteoinductive mechanisms.

As early as 1889, Senn reported using the demineralized bone matrix (DBM) bovine bone as a vehicle for delivery of antiseptics (iodoform) in patients with osteomyelitis. In 20th century Leriche and Policard, Lacorix, Levander, Urist and Huggins studied extensively on induced bone formation. It was not until 1965 that an orthopedic surgeon, Dr. Marshal Urist, published his seminal work, in which he demonstrated the osteoinductive properties of DBM by showing its ability to induce bone formation when implanted ectopically in rat muscle pouches, now known as Urist model, continues to be used today as an accurate indicator of osteoinductive potential.[67]

Demineralized freeze dried bone allograft (DFDBA) consists primarily of collagen with some residual proteins; including an array of bone growth and differentiation factors like bone morphogenetic proteins (BMPs), which constitute osteoinductive components of bone. In addition to BMPs, other growth factors such as platelet-derived growth factor and transforming growth factor-β are also present.[89]

BMP has been shown to up regulate the expression of cbfa1- the master switch that regulates osteoblast differentiation. BMP exerts its effects primarily through the Smad pathway although other mechanisms have been suggested.[10]

Alloplasts or synthetic graft materials such as bioactive glass are osteoconductive, composed entirely of elements naturally occurring in the bodyv (silica, calcium, phosphorous, oxygen and sodium) bonds directly to bone tissue and soft-tissue.[11]

Once implanted, bioactive glass leaches ions into the surrounding tissue as sodium in the glass begins to exchange with hydrogen in the tissue fluids, calcium and phosphorous also leach out into the tissues leaving behind a silica-gel layer. The calcium and phosphorous are redeposited, leading to the formation of a hydroxyl-carbonate apatite layer. This is very similar in composition to that of the mineral phase of bone and includes organic components such as collagen fibers, which are incorporated into the structure.[12]

In this study, the soft- and hard-tissue response to bioactive glass and DFDBA in the treatment of intrabony defects periodontal defects was evaluated.

MATERIALS AND METHODS

Ten patients (4 females and 6 males) with age ranging from 21 to 45 and exhibiting at least a pair of contra lateral vertical osseous defects were recruited into the study. Patients suffering from any systemic disease, pregnancy, lactation, under any medication and who underwent any periodontal therapy were excluded. Once the patient was included into the study, the entire study protocol was explained in detail, after which a consent form was signed.

All patients received complete scaling and root planning and oral hygiene instructions prior to surgical treatment.

The following clinical and radiological parameters were recorded at baseline, 3 months, 6 months and 12 months after the surgery.

Plaque index[13]

Gingival index[13]

Probing pocket depth [Figure 1].[1415]

Figure 1

Pre-operative pocket depth and clinical attachment level measurements

Clinical attachment level (CAL) [Figure 1].[1415]

Percentage bone/defect fill.[1617]

Radiographic assessments of percentage bone fill

Intra-oral periapical radiographs of each defect site with millimeter grid in place were obtained using long cone/paralleling radiographic technique. Radiographs were taken at baseline, 3 months, 6 months and 12 months and were measured with the help of the formula:

Patients with residual probing depths that remained ≥6 mm were continued into the surgical phase of treatment.

Surgery protocol

Surgical procedures were performed under aseptic conditions with administration of local anesthesia. Sulcular incisions were given and full thickness mucoperiosteal flap was elevated. Defect sites were thoroughly scaled and root planed and all granulomatous tissue was removed [Figure 2]. Defect on one-side was treated with DFDBA (Grafton)® in putty form and on the other side with bioactive glass (PerioGlas)® [Figure 3]. Flaps were repositioned and closed by using 4-0 black silk interrupted sutures [Figure 4].

Figure 2

Intrabony defects

Figure 3

Placement of graft

Figure 4

Sutures placed

Post-operatively, subjects were instructed to take antibiotics and analgesics for 3 days and were advised to refrain from tooth brushing, flossing and interdental cleaning techniques in the treated area. At 1 week sutures and any plaque present in the area were removed and patients were asked to start brushing in the treated area.

A recall appointment was made at 3 month, 6 month, 9 months and 12 months. At these visits, professional prophylaxis and oral hygiene reinforcement were performed and clinical parameters recorded [Figure 5] and intraoral periapical radiographs taken [Figures 6 and 7].

Figure 5

12 months post-operative pocket depth and clinical attachment level measurements

Figure 6

Pre-operative and 12 months post-operative intra-oral periapical radiograph in relation to 16

Figure 7

Pre-operative and 12 months post-operative intra-oral periapical radiograph in relation to 26

Statistical analysis

Data was expressed as mean ± standard deviation of the parameters evaluated. In both groups, the parameters were evaluated at baseline, 3rd month, 6th month and 12th month post-operatively. Comparisons were made within each group between baseline, 3rd month, 6th month and 12th month evaluation using the one-way analysis of variance followed by Bonferroni test.

RESULTS

All 10 patients who were enrolled in the study returned for scheduled maintenance visits. Wound healing in the grafted areas was excellent.

Soft tissue measurements

The mean plaque index score was 1.67 ± 0.44 mm at baseline which was reduced gradually, i.e., 0.77 ± 0.44 mm (3 months), 0.51 ± 0.34 mm (6 months) and 0.40 ± 0.48 mm (12 months) post-operatively. Comparing to the baseline value, the reduction in plaque index score at different time intervals was statistically significant (P < 0.003) [Table 1].

Table 1

PI

The baseline mean gingival index score was found 1.20 ± 0.42, which was reduced to 0.32 ± 0.52 (3 months), 0.40 ± 0.52 (6 months) and 0.40 ± 0.52 after 12 months post-operative. When compared to the baseline, the difference in mean gingival index score at different time intervals was highly significant (P < 0.005) [Table 2]. This improvement in gingival status may be attributed to the maintenance of optimum oral hygiene by the patient and frequent recall visits.

Table 2

GBI

Treatment of the intrabony defects with the Bioactive Glass or DFDBA led to an overall improvement in probing depth and CAL when compared to baseline. At 12 months, post-operatively bioactive glass resulted in 1.8 ± 0.1 mm in probing depth reduction while DFDBA decreased probing depth by 2.5 ± 0.1 mm. A gain in clinical attachment of 1.7 ± 0.2 mm was obtained with bioactive glass while DFDBA sites gained 2.4 ± 0.1 mm. A significant probing depth reduction [Table 3] and gain in CAL [Table 4] were obtained from baseline (P < 0.000**) with both the therapies.

Table 3

Probing pocket depth for both DFDBA and bioactive glass at baseline, 3 months, 6 months and 12 months

Table 4

CAL for both DFDBA and bioactive glass at baseline, 3 months, 6 months and 12 months

At 6 months, there was no significant difference between bioactive glass and DFDBA as far as soft-tissue measurements were concerned [Table 5] and at 12 months post-operative there was a significant difference (P < 0.001*) between the two groups with greater probing depth reduction and CAL gain in sites treated with DFDBA [Table 6].

Table 5

Comparison of mean score between groups at 6 months

Table 6

Comparison of mean scores between groups at 12 months

Radiographic measurements

The percentage of bone fill obtained at sites treated with bioactive glass [Table 7] and DFDBA [Table 8] were measured and compared with baseline at 3, 6 and 12 months.[1617] The total amount of average percentage of bone fill obtained by bioactive glass at the end of 6 months is 63.04% and DFDBA is 53.86%. The mean difference between the two sites is not statistically significant (P < 0.016) and neither therapy was superior to the other when compared at the end of 6 months [Table 9].

Table 7

Radiographic measurements in sites treated with bioactive glass

Table 8

Radiographic measurements in sites treated with DFDBA

Table 9

Bone fill obtained at both sites at 3 months, 6 months and 12 months

When compared at the end of 12 months, sites treated with bioactive glass showed 56.99% bone fill while sites grafted with DFDBA resulted in 64.76% bone fill. The total average percentage of bone fill obtained with the sites grafted with DFDBA at the end of 12 months showed statistically significant (P < 0.05*) [Table 9] than sites treated with bioactive glass.

DISCUSSION

The present study was carried out to compare the efficiency of bioactive glass (osteoconductive) material and DFDBA (osteoinductive) material. 10 patients each with contra lateral vertical osseous defects were enrolled into the study so that individual differences in the healing capacity may not influence the results attributed to the graft materials.

The results of this study suggest that both bioactive glass and DFDBA used as regenerative graft materials yield generally favorable clinical results in periodontal intrabony defects and that there are essentially no differences in results between the two materials when clinical parameters were measured at 6 months. However 12 months post-surgery, there is indeed a significant difference between the two materials with sites grafted with DFDBA showing better reduction in probing depth and gain in CAL when compared to that of bioactive glass.

Soft-tissue parameters obtained in this study at 6 months shows that bioactive glass resulted in 2.1 mm reduction in probing depth while DFDBA grafted sites resulted in 1.9 mm decrease in pocket depth. The results obtained were similar to those found by Lovelace et al.[18] in their 6 month reentry study, where they reported 3.1 mm of probing depth reduction with bioactive glass and 2.6 mm reduction with DFDBA. Bowen et al.[1920] reported 2.9 mm of probing depth reduction with porous hydroxyapatite (HA) and 3.0 mm with DFDBA. At 6 months, probing depth values were similar to the previous studies,[21] whereas at 12 months, bioactive glass treated sites showed 1.8 mm and DFDBA sites with 2.5 mm reduction in probing depth, which is statistically significant (P < 0.01*).

The results obtained in this study were similar with previous studies. At 6 months, there was a gain in CAL of 2.0 mm with bioactive glass and 1.9 mm with DFDBA and at 12 months bioactive glass treated sites showed 1.7 mm and DFDBA treated sites showing 2.4 mm gain in CAL, which is statistically significant (P < 0.01*). The variations in probing depth reduction and CAL gain obtained in the sites treated with bioactive glass might be due to the resorption property of the graft material.[22]

Radiographic analysis is carried out according to the previous studies by Chapple et al. (2002) and Mehtha et al. (2005) to measure the amount of bone fill in the grafted sites using computer-aided 3D interactive applications by taking the CEJ and Root apex as standard anatomic points. Sites grafted with bioactive glass exhibited greater bone fill at 6 months when compared to sites grafted with DFDBA, which however was statistically not significant. However conversely at 12 months, sites treated with bioactive glass exhibited 56.99% bone fill and 64.76% bone fill for DFDBA sites, which is statistically significant (P < 0.05*).

Bioactive glass material has property of radio-opacity in radiographic interpretation, whereas DFDBA used is in putty form and radiolucent in its property due to the removal of calcium during demineralization process. Therefore, the radio-opacity of bioactive glass particles showed increased percentage of bone fill at 6 months when compared to DFDBA and at 12 months due to the resorption of bioactive glass particles led to the decreased percentage of bone fills.

Bone fill obtained in the present study was 56.99% for bioactive glass and 64.76% for DFDBA at the end of 12 months. These results compare favorably to those found by Lovelace et al. (1998) in which they reported 2.7 mm (61.8%) for bioactive glass and 2.8 mm (62.5%) for DFDBA. Bowen et al. (1989) reported 2.1 mm (53%) of bone fill with porous HA and 2.2 mm (61%) bone fill with DFDBA. and Oreamuno et al. (1990)[23] compared porous hydroxyapatite to DFDBA and found a defect fill of 3.3 mm with HA and 2.3 mm with DFDBA.

It has been reported that DFDBA varies in its ability to induce bone formation. This variability occurs between and within bone banks, with some DFDBA failing to induce bone formation in ectopic sites.[2425]

In this study, 4 patients showed bilateral 3-wall defects while others had 2-wall or a combination of 2 and 3 wall defects. It has been reported that 3-wall defects have the highest potential for regeneration when grafting procedures are used. In addition, the defects varied according to the depth and width, with the aforementioned studies reporting better predictability with deep, narrow defects versus shallow, wide ones. It is hard to obtain stringent control for these variables in a clinical investigation, but the potential effect of this variability on the results needs to be realized. However, even in the best of circumstances, it is impossible to find matched osseous defects. Randomization may help to control this variable.

The present study has been concerned with clinical and radiographic observations using two different graft materials and has been restricted by a small sample. Future studies should incorporate precise radiographic evaluation using the advanced digital imaging facilities available.