A clinical and radiological evaluation of the relative efficacy of demineralized freeze-dried bone allograft versus anorganic bovine bone xenograft in the treatment of human infrabony periodontal defects: A 6 months follow-up study.

BACKGROUND: The ultimate goal of periodontal therapy entails regeneration of the periodontal tissues lost as a consequence of periodontitis. Predictable correction of vertical osseous defects has however posed as a constant therapeutic challenge. The aim of our present study is to evaluate the relative efficacy of demineralized freeze-dried bone allograft (DFDBA) vs anorganic bovine bone xenograft (ABBX) in the treatment of human infrabony periodontal defects.
MATERIALS AND METHODS: 15 patients with 30 bilaterally symmetrical defect sites in either of the arches, in the age group of 25-50 years were selected as part of split-mouth study design. Defect-A (right side) was grafted with DFDBA while Defect-B (left side) was grafted with ABBX. Various clinical and radiographic parameters viz. probing depth(PD), clinical attachment level(CAL) and linear bone fill were recorded preoperatively, 12- & 24-weeks postoperatively.
RESULTS: Both defect-A & defect-B sites exhibited a highly significant reduction in probing depth, and gain in clinical attachment level and linear bone fill at 12-weeks & at the end of 24-weeks. Comparative evaluation between the study groups revealed a statistically non-significant reduction in probing depth (P<0.1) and mean gain in linear bone fill (P<0.1). However, there was a statistically significant gain in clinical attachment level (P<0.05) in Defect-A (CD=0.356) as compared to Defect-B (CD=0.346).
CONCLUSIONS: Within the limits of this study, both the materials viz. ABBX and DFDBA are beneficial for the treatment of periodontal infrabony defects. Both the materials were found to be equally effective in all respects except the gain in attachment level, which was found to be more with DFDBA. Long-term studies are suggested to evaluate further the relative efficacy of the two grafts.

INTRODUCTION

Periodontal disease, one of the most common reasons for the loss of teeth, results in the extension of the inflammation from the marginal gingiva into the supporting periodontal tissues viz. periodontal ligament, cementum, and alveolar bone. The consequent destruction of the alveolar bone is ultimately responsible for the exfoliation of the tooth. Hence, the aim of the periodontal therapy is to regenerate the lost supporting tissues thus requiring the formation of new cementum, deposition of bone, insertion of functionally oriented new connective tissue fibers in the newly formed bone and cementum, and organization of a competent gingival unit.[1]

These days clinical periodontal research focuses on the utilization of bone grafts,[234] the principles of guided tissue regeneration[5] or combination of the both[6] to achieve regeneration. Until date, the materials demonstrated to meet the histologic criteria for periodontal regeneration are autografts, allografts, anorganic bovine bone xenografts (ABBXs), and xenogenic enamel matrix derivative.[2]

Although osseous autografts have a laudable record for many applications in dentistry, yet due to the morbidity associated with them, allografts have been introduced as an alternative among which demineralized freeze-dried bone allograft (DFDBA) has shown promising results due to its availability, safety, osteoinductive, and osteoconductive properties.

Results of human histologic studies have shown that DFDBA can successfully regenerate bone as well as cementum in the treatment of periodontal defects,[78] and also regenerate bone around implants,[9] in localized alveolar ridge augmentation procedures, in nonorthoptic sites viz., muscles and connective tissues,[10] in sinus elevation[11] etc.

At the present times xenograft, obtained from a donor of different species, is another option for use as a bone graft material. ABBX is a natural microporous hydroxyapatite skeleton,[12] which is similar in structure to human cancellous bone. This material enhances the bone formation due to its osteoconductive properties[313] and undergoes remodeling during a slow resorption process.[3] Although it lacks osteoinductive activity, in many studies it has been reported to facilitate osteogenesis in the presence of osteogenic precursor cells.[14]

Both these materials viz., DFDBA and ABBX, have shown good results when tried individually, but the literature is still deficient in their comparative studies. In this study, an attempt has been made to evaluate and compare clinically and radiographically, the efficacy of DFDBA and ABBX in the treatment of periodontal osseous defects [Figure 1].

Figure 1

Regenerative bone graft materials employed

MATERIALS AND METHODS

Study population

A split mouth study was designed with an age group of 25-50 years. A total of 15 patients were selected from among the patients visiting the Department of Periodontology, Punjab Government Dental College and Hospital, Amritsar. The criteria for the selection of the patients were as follows:

Presence of almost identical bilateral infrabony defects in relation to the posterior teeth, of either the maxilla or the mandible, as determined by clinical and radiological evaluation

Patients who were not suffering from any systemic disease

Patients who had no known history of allergy

Patients who were nonsmokers.

After an explanation of the proposed study criteria, including alternative treatments and potential risks and benefits, the participants were asked to sign a consent form prior to surgery. The study was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2000 after receiving clearance from the ethical clearance committee of the institute.

Materials

DFDBA: In this study was prepared, according to a standardized technique,[15] from the parts of long bones obtained from the Department of Orthopedics, Government Medical College, Amritsar and stored in 10% formaldehyde solution until the time of preparation. The cortical portion of the bone was selected for the same since it is known to contain more bone morphogenetic proteins (BMPs) in comparison to the cancellous bone[16] (particle size 0.3-1 mm)

ABBX: Bio-Oss® spongiosa granules (geistlich Pharma AG, bahnhofstrasse 40CH-6110, Wolhusen, Switzerland) (particle size 0.25-1 mm, Geistlich Biomaterials) was used.

Methods

Preoperative

Routine laboratory investigations were carried out for each patient following which oral prophylaxis was performed and the patient was instructed to adopt meticulous home care measures to control the dental plaque. The oral hygiene status was reviewed by disclosing the presence or absence of tooth accumulated material at weekly intervals until he/she could maintain a satisfactory level of oral hygiene. Occlusal adjustment was performed, if trauma from occlusion was diagnosed

Radiographs by standardized technique (using a millimeter grid along with the X-ray film and employing long cone/paralleling technique) were taken preoperatively to ascertain the depth of the infrabony defect [Figures 2a 3a]. The defect depth was measured from a fixed reference point (the adjacent cuspal tip) to the most apical point of the base of the defect

Figure 2

(a) Radiographic comparison of osseous defect fill at DFDBA site at Baseline, (b) 12 weeks post-operative, (c) 24 weeks post-operative

Figure 3

(a) Radiographic comparison of osseous defect fill at ABBX site at Baseline (b) 12 weeks post-operative (c) 24 weeks post-operative

Preoperative assessment of clinical parameters viz., probing depth (PD), and clinical attachment level (CAL) was performed using stents, immediately prior to surgery.

Operative

The identical infrabony defects were designated as “defect-A” for right infrabony defect [Figure 4] and “defect-B” for left infrabony defect [Figure 5]. Full thickness mucoperiosteal flaps were raised to gain access to the infrabony defects. Following the root planning and debridement of the defect sites [Figures 6 and 7], DFDBA was placed in “defect-A” [Figure 8] and ABBX was placed in “defect-B” [Figure 9] and interrupted interdental sutures were given [Figures 10 and 11].

Figure 4

Crevicular incision at the surgical site (Defect-A)

Figure 5

Crevicular incision at the contra-lateral surgical site (Defect-B)

Figure 6

Osseous defect subsequent to debridement (Defect-A)

Figure 7

Osseous defect subsequent to debridement (Defect-B)

Figure 8

Following the placement of demineralized freeze-dried bone allograft

Figure 9

Following the placement of anorganic bovine bone xenograft

Figure 10

Surgical site after suturing (Defect-A)

Figure 11

Surgical site after suturing (Defect-B)

Postoperative

Immediate postoperatively, the patients were prescribed antibiotic therapy along with an antiinflammatory agent. Routine written and oral postoperative care instructions were given to each patient. Sutures were removed 1 week after the surgery. Postsurgical examination and supragingival cleaning of the surgical site was done. The patients were recalled at monthly intervals for oral hygiene assessments by disclosing the presence/absence of tooth accumulated materials and to carry out supragingival scaling. Postoperative assessments viz. PD, attachment level and radiographs for calculating the linear bone fill were performed at 12 and 24 weeks postoperatively. The observations, thus, made were statistically analyzed.

RESULTS

It was observed that both the materials were well-tolerated by all the patients with no adverse tissue reaction, infection or delayed healing reported during the course of the study.

The mean preoperative and postoperative PD, CAL and linear bone fill at baseline, 12 weeks and 24 weeks postoperative for both defect-A and defect-B are enumerated in Table 1.

Table 1

Mean PD, CAL and infrabony defect depth for defect-A (DFDBA) and defect-B (ABBX) in mm

The mean reduction or gain in postoperative PD, CAL and linear bone fill for both defect-A and defect-B after 12 weeks and 24 weeks postoperatively [Figures 2b, c and 3b, c] and between 12 weeks and 24 weeks postoperatively are summarized in Table 2.

Table 2

Mean reduction in PD and gain in CAL and linear bone fill for defect-A (DFDBA) and defect-B (ABBX) in mm

A comparison of defect-A and defect-B for mean reduction in PD, mean gain in CAL and mean linear bone fill is presented in Table 3.

Table 3

Comparison of defect-A (DFDBA) and defect-B (ABBX) for the chosen parameters in mm

Student's t-test (for paired samples) was applied to statistically evaluate the data since the observation at the two points in time were expected to be closely related to each other. A statistically significant reduction in PD with both DFDBA and ABBX was observed at all 3 time-intervals. In addition, a significant gain in CAL and linear bone fill was seen with DFDBA alone at all 3 time-intervals.

In order to examine whether the improvement in PD, CAL and linear bone fill during the three successive points in time for the two materials were of similar nature or not, the data were subjected to two-way analysis of variance (ANOVA). The patients were regarded as replicates and the combination of materials and time-intervals as treatments and results thus obtained have been tabulated in Tables 4-6.

Table 4

Two-way ANOVA table for comparing reduction in PD in respect of defect-A (DFDBA) and defect-B (ABBX)

Table 6

Two-way ANOVA table for comparing gain in linear bone fill in respect of defect-A (DFDBA) and defect-B (ABBX)

A break-up of the variability between treatment combinations into three components; that is, due to (a) The materials used in the defects, (b) the time-intervals and (c) the interaction between materials and time-intervals revealed that the difference in between the materials with respect to the reduction in PD was not significant. An almost similar pattern of reduction in PD was experienced in both the defects. The computed values of critical difference also reveal a statistically significant reduction in PD during all time-intervals as depicted in Table 7.

Table 7

Mean values of reduction in PD in mm

The ANOVA approach displayed a statistically significant difference in the results between the materials used with respect to CAL, though the interaction between individual materials and time-intervals was nonsignificant. The observed values of critical difference revealed that over the entire period of the study span, the material used in defect-A was significantly superior to that for defect-B [Table 8].

Table 8

Mean values of gain in attachment level in mm

The results of the ANOVA approach showed that the difference between the materials used was not significant. However, the gain in linear bone fill during different time-intervals differed significantly at 1% probability level. The critical difference values express an almost uniform rate of linear bone fill over the entire study span as depicted in Table 9.

Table 9

Mean values of gain in linear bone fill in mm

DISCUSSION

Periodontal disease occasionally involves the alteration in the morphological features of the bone, which may include the reduction in bone height, formation of infrabony defects, osseous craters, ledges, etc.

Demineralized freeze-dried bone allograft by virtue of its osteoinductive[1718] and osteoconductive[19] properties has provided sufficient evidence in the literature that it supports the formation of new attachment apparatus in the infrabony defects. The osteoinductive property has been attributed to the exposure of the BMPs and growth factors following the acid demineralization process of the allograft.[202122] These BMPs and growth factors permit rapid revascularization and hard tissue in growth in the osseous defects thereby promoting periodontal regeneration. However, studies have shown that the amount of BMPs present in the graft particles may vary depending on the donor source.[23] This lead us to evaluate the relative efficacy of another bone graft material, that is, ABBX with respect to DFDBA.

However, ABBX has been proved to be osteoconductive only though a few studies have stated that it facilitates osteogenesis in the presence of osteogenic precursor cells.[1012]

The selection of two- and three-walled infrabony defects was based on the results obtained from controlled clinical trials providing evidence that three-walled osseous defects allow better containment, stability, and increased blood supply to the graft.[24] Hence, two- and three-walled defects have a greater healing potential than one-walled defects after conventional and regenerative surgery.

In this study, it was observed that both the materials were well-tolerated by the patients as no unusual findings with regard to the postoperative healing as well as no sign or symptom of any other allergic manifestation was elicited. These findings concur with the findings of Schwartz et al.[25] and Hernandez et al.[26]

The soft tissue parameters viz. PD and attachment level were ascertained clinically, whereas, the hard tissue parameter such as depth of the infrabony defect was ascertained radiographically and the results thus obtained were subjected to statistical evaluation.

The defect-A showed a mean reduction of PD to be 2.13 ± 0.32 mm at 12 weeks postoperatively and 2.80 ± 0.39 mm at 24 weeks postoperatively, which were statistically significant at 1% probability level, implying thereby, that substantial pocket depth reduction had taken place as also shown by Lovelace et al.[27] and Katuri et al.[28]

The defect-B showed a mean reduction of PD to be 1.47 ± 0.26 mm at 12 weeks postoperatively and 2.27 ± 0.35 mm at 24 weeks postoperatively, which were also statistically significant at 1% probability level. These findings compare favorably with those found by Hutchens[29] and Yukna et al.[30]

This reduction in both the cases may be attributed to the resolution of the inflammatory component consequent to access flap surgery and the subsequent plaque control regime adopted by the patients.[3132]

On comparing the mean pocket depth reduction obtained with the two materials (by ANOVA approach), we infer that the difference in their results was not significant. A similar pattern of pocket depth reduction with respect to time was experienced in both the defects. However, significant difference was presented by both the materials during each of the time-intervals (i.e. preoperative to 12 weeks postoperative, preoperative to 24 weeks postoperative, and 12 weeks postoperative to 24 weeks postoperative) indicating that the reduction was taking place throughout the span of the study.

The DFDBA group showed a mean gain in attachment level of 2.07 ± 0.32 mm at 12 weeks postoperatively and 2.80 ± 0.34 mm at 24 weeks postoperatively, which was found to be a substantial gain, statistically (P < 0.01), which is in accordance with those of Pearson et al.[33] and Oreamuno et al.[34]

The ABBX group showed a mean gain in attachment level of 1.40 ± 0.19 mm at 12 weeks postoperatively and 2.27 ± 0.28 mm at 24 weeks postoperatively, which was proved to be a substantial gain, statistically (P < 0.01). These findings are similar to those of Hutchens[29] and Yukna et al.[30]

On comparing the gain in mean attachment level obtained with the two materials (by ANOVA approach), we infer that a significant difference (P < 0.05) was present in the amount of gain obtained between the two defect sites. Better results are obtained with DFDBA as compared to ABBX. The gain in attachment level followed a similar pattern over both the defects and a substantial gain was noticed on the completion of the study span.

A mean linear bone fill of 1.45 ± 0.21 mm at 12 weeks postoperatively and 3.17 ± 0.55 mm at 24 weeks postoperatively was obtained with the DFDBA group. The result was found to be statistically significant at 1% probability level and was shown to be in conformity with those of Richardson et al.[35]

Concurrent to the findings of Yukna et al.[30] in our study a mean linear bone fill of 1.44 ± 0.23 mm at 12 weeks postoperatively and 3.76 ± 0.57 mm at 24 weeks postoperatively was obtained with the ABBX group and this was also significant at 1% probability level.

On comparing the mean linear bone fill obtained with the two materials (by ANOVA approach) we infer that the difference in their results was not significant. A similar pattern of linear bone fill with respect to time was obtained in both the defects. It was also observed that the rate of linear bone fill progressed in an almost uniform/similar rate over the entire study span.

The results of this study match those of a previous study by Richardson et al.,[35] which compared DFDBA and ABBX in the treatment of infrabony defects, in all respects except the gain in attachment level. In our study, the gain in attachment level was found to be more significant with the DFDBA (CD = 0.356) than with the ABBX at 5% probability level (CD = 0.346).

The difference in the mean measurements of this study and those cited above may be contributed by factors such as the differences in study designs, differences in patient populations, initial defect depth, criteria used in recording and analyzing the variable, operator's experience, and other variables.

It is important to emphasize that the data generated by this study derived from 24 weeks observations, a relatively short period of time when one considers the long term success of regenerative procedures. Hence, long-term studies are suggested to evaluate further the relative efficacy of the two grafting materials.

CONCLUSION

Within the constraints of this study, both the materials viz. ABBX and DFDBA have shown promising results for the treatment of periodontal infrabony defects thus warranting long-term studies with a larger sample size to explore their true regenerative potential to the maximum.

Table 5

Two-way ANOVA table for comparing gain in attachment level in respect of defect-A (DFDBA) and defect-B (ABBX)