A clinical evaluation of a bioresorbable membrane and porous hydroxyapatite in the treatment of human molar class II furcations.

BACKGROUND: The ultimate goal of periodontal therapy is predictable regeneration of a functional attachment apparatus destroyed as a result of periodontitis. Reconstructive procedures have been used with varying success during the past decades to accomplish this goal. AIM: To evaluate whether the use of porous hydroxyapatite alone or a bioresorbable membrane alone would enhance the clinical results in the treatment of class II furcation defects in human lower molars.
MATERIALS AND METHODS: Fifteen patients with chronic periodontitis, aged between 39 and 49 years, with a pair of similar bilateral class II furcation defects (classification of Hamp et al.) in mandibular first molars were selected. A split-mouth design was incorporated and the selected 30 furcation defects were assigned to one of the two treatment groups, i.e., Group I treated with a bioresorbable membrane from bovine-derived collagen guided tissue regeneration membrane and Group II treated using porous hydroxyapatite bone graft material on the contralateral sides. Evaluation of clinical parameters, probing depths and attachment levels, and radiographs was done preoperatively and 6 months postoperatively.
RESULTS: Both the groups showed statistically significant mean reduction in probing depths and gain in clinical attachment levels and linear bone fill. Comparison between Group I and Group II showed insignificant difference.
CONCLUSION: Within the limits of this study, both the treatment modalities are beneficial for the treatment of human mandibular class II furcation defects.

INTRODUCTION

Progressive periodontitis can lead to tooth loss through the destruction of its attachment apparatus. When continued function necessitates additional periodontal support, optimal treatment should include not only periodontal infection control but also regeneration of the lost periodontium.[1]

A furcation defect has long been recognized as one of the most challenging treatment modalities, mainly due to complex anatomical features and limited accessibility of furcal areas.[2] Proper diagnosis of the furcation lesions and knowledge of furcal anatomy are the corner stones for optimal therapy.[3]

Class II furcation lesions have traditionally been treated by closed scaling or resection techniques, and the results have been largely unpredictable. More recently, techniques aimed at using bone grafts and/or barrier materials have been evaluated in regenerating furcation defects.[4] Encouraging results have been obtained in studies by Murphy et al.,[5] but the ideal material to use has not been unequivocally validated.

New attachment achieved by guided tissue regeneration (GTR), the procedure in which a barrier is utilized to exclude epithelium from the root surfaces,[6] has been shown to partially regenerate lost periodontal tissue with new bone, periodontal ligament, and cementum.[7]

To date, there is consensus that GTR procedures have resulted in significant gains in clinical attachment levels (CAL) both horizontally and vertically in mandibular class II furcations[8] through new connective tissue attachment and the formation of cementum and bone in periodontal defects.[9] Alternatively, in grafting procedures, bone replacement grafts (BRGs) have achieved similar results to GTR barriers in mandibular class II furcations.[10] Autogenous intraoral and extraoral bone, frozen allografts, freeze-dried allografts with and without the addition of host bone, ceramic materials,[11] and bioactive glasses have resulted in a 55% overall improvement.

Porous hydroxyapatite (HA) has been shown to be osteoconductive when placed in long bones and mandibles of dogs,[12] and similar patterns of bone growth have been reported in periodontal defects in dogs and humans.[13] Clinical studies have shown apparently less gingival recession and more defect fill when porous HA is used.[14]

This study was designed to evaluate whether the use of porous HA alone or a bioresorbable membrane alone would enhance the clinical results in the treatment of class II furcation defects in human lower molars.

MATERIALS AND METHODS

Fifteen patients with chronic periodontitis, aged between 39 and 49 years, with a pair of similar bilateral class II furcation defects (classification of Hamp et al.) in mandibular first molars as determined by a clinical and radiological evaluation were selected from the Department of Periodontics. A split-mouth design was incorporated and the selected 30 furcation defects were assigned to one of the two treatment groups, i.e., Group I treated with a bioresorbable membrane from bovine-derived collagen GTR membrane and Group II treated using porous HA bone graft material on the contralateral sides. The patients were followed up for a period of 6 months postoperatively. The institutional review board (IRB) approved the protocol used in this study (No. MDC/2007/7/1).

The patients selected were non-alcoholic and had no history of any systemic disease and allergies. For patient screening, a detailed clinical history was obtained and clinical examination was conducted as per the case history proforma.

After initial patient screening was completed, etiotropic phase was followed. All patients were motivated and educated about oral hygiene procedures. Oral prophylaxis was done for all patients and they were evaluated after 2-3 weeks. Approximately 4 weeks after initial therapy, patients were re-evaluated to assess clinical parameters and plaque control. At this stage, patients were selected for the surgical phase. Informed consent was obtained from all the patients after explaining them the protocol/procedure and the benefits of the study.

Clinical probing depths and attachment levels were recorded immediately before surgery. Radiographs were taken by a standardized technique and 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.

Paralleling cone technique was used along with the X-ray to ensure accuracy in the measurements. Following data collection, the decision to use porous HA or a bioabsorbable collagen membrane was determined randomly.

Figures 1 and 2 show the preoperative furcation defects of groups I and II in relation to 36 and 46, respectively, and preoperative IOPA X-rays taken in relation to left lower first molar (36) and right (46) regions are given in Figures 3 and 4, respectively.

Figure 1

Preoperative furcation defect of Group I in relation to 36

Figure 2

Preoperative furcation defect of Group II in relation to 46

Figure 3

Preoperative IOPA X-ray of Group I site, i.e., 36 region

Figure 4

Preoperative IOPA X-ray of Group II site, i.e., 46 region

Surgical procedure

The patients were pre-medicated using systemic antibiotics (amoxicillin 250 mg capsules tid) 1 day before surgery. All patients were also prescribed systemic analgesics (brufen 400 mg tablet) 1 h before the surgical procedure.

The procedure was done with all necessary precautions. The surgical area was anaesthetized by local anesthetic techniques using 2% xylocaine with adrenaline 1:80,000 dilution. The procedure was done under proper aseptic precautions using continuous aspiration to keep the surgical site clean.

In group I sites

Using a sulcular incision, a full-thickness flap was elevated at the furcation site, extending at least one tooth mesial and distal to the treated tooth, and the reflected flap extended apically below mucogingival junction [Figure 5]. These sites were treated by the resorbable membrane which was trimmed in order to cover the class II furcation defect and about 3 mm of the surrounding alveolar bone. The membrane was then tied with the vicryl resorbable suture material internally [Figure 6]. The reflected flaps were repositioned coronally and sutured externally using sling sutures (4-0 black braided silk) for primary soft-tissue closure at the site over the regenerative material and the furcation entrances.

Figure 5

The exposed site of the furcation defect

Figure 6

The placement of an absorbable collagen membrane at the site of the furcation defect

In group II sites

The furcation defect was debrided, root planing was done with Gracey curettes, and osteoplasty was performed depending upon the nature and contour of the furcation defect. Porous HA particles were mixed with saline and the defect was filled gently in small increments to the highest level of the furcation defect [Figure 7]. The flaps were replaced to their original level using interrupted sutures with 4-0 black braided silk and postoperative instructions were given to the patients. Patients were reviewed at the end of 6 months [Figures 8 and 9] and postoperative IOPA X-rays were taken [Figures 10 and 11].

Figure 7

The placement of porous HA at the furcation defect

Figure 8

Postoperative furcation defect of Group I 6 months postoperatively

Figure 9

Postoperative furcation defect of Group II 6 months postoperatively

Figure 10

Postoperative IOPA X-rays of Group I at the end of 6 months

Figure 11

Postoperative IOPA X-rays of Group II at the end of 6 months

Patients were prescribed to take amoxicillin 250 mg tid for a total period of 7 days. Ibuprofen 600 mg every 8 h was given for 2 days postoperatively. All patients were instructed about oral hygiene maintenance at the surgical area and other areas in the oral cavity. Patients were recalled after 7-14 days for suture removal and COE pack and the patients were asked to ref rain from mechanical plaque control for 2 weeks at the surgical site.

The parameters (clinical measurements and standardized radiographs) were evaluated at baseline and postoperatively after 6 months.

RESULTS

All patients showed good compliance and the healing period was uneventful for both treatment groups, without infection or complications.

The mean differences in the Probing Depth (PD), Relative Attachment Levels (RAL) which includes Horizontal Clinical Attachment Level (H-CAL) and Vertical Clinical Attachment Levels (V-CAL), Depth of Defect (DOD), and Radiographic Defect Fill (RDF) between the groups, i.e., clinical and radiological parameters obtained at the baseline and at 6 months postoperatively were analyzed statistically. Microsoft Excel spreadsheet program 2007 was used for statistical analysis. Bilateral sites for bone graft and GTR were analyzed using the Student's paired t-test and unpaired t-test.

The overall results including baseline recordings as well as the final outcome of both treatments are presented in Tables 1–8. Baseline analysis showed no significant differences between Group I and Group II for any variables assessed.

Table 1

Comparison of horizontal probing depth between Group I and Group II at baseline and 6 months postoperatively

Table 8

Comparison of values of vertical defect fill between Group I and Group II

The two groups I and II were then comparatively evaluated over three time intervals using the independent Student's t-test for equal sample sizes, because the samples were collected from randomly selected individuals from the same population at different times.

The mean values of PD [Tables 1 and 2] and CAL [Tables 3 and 4] were recorded for Group I and Group II, both preoperatively, i.e., baseline, and 6 months postoperatively. The efficacy of the two treatment modalities at baseline and 6 months postoperatively was evaluated using paired Student's t-test because the observation at the two points in time were expected to be closely related to each other.

Table 2

Comparison of vertical probing depth between Group I and Group II at baseline and 6 months postoperatively

Table 3

Comparison of horizontal clinical attachment levels between Group I and Group II at baseline and 6 months postoperatively

Table 4

Comparison of vertical clinical attachment levels between Group I and Group II at baseline and 6 months postoperatively

The mean change in horizontal PD between baseline and 6 months postoperatively (intragroup) in Group I and in Group II was statistically significant (P < 0.05).

Table 1 shows the comparison of horizontal PD values between Group I and Group II at baseline and 6 months postoperatively.

Table 2 shows the comparison of vertical PD values for Group I and Group II at baseline and 6 months postoperatively.

On comparative evaluation of the two groups, almost a similar pattern of reduction in PD was observed in both the groups.

The difference in mean horizontal CAL between Group I and Group II (intergroup) at baseline and 6 months postoperatively was not significant (P > 0.05). So, a mean gain of 1.47 mm in Group I and 1.86 mm in Group II sites was achieved. Hence, more gain in horizontal attachment level was seen in Group II sites than in Group I sites. The mean change in horizontal CAL between baseline and 6 months postoperatively (intragroup) in Group I and in Group II was statistically insignificant (P < 0.05) [Table 3].

Table 3 shows the individual values and mean horizontal clinical attachment for Group I and Group II at baseline and 6 months postoperatively.

The difference in vertical CAL between Group I and Group II (intergroup) at baseline was not significant (P > 0.001) and at 6 months postoperatively was statistically significant (P < 0.05). A mean gain of 1.53 mm for Group I and 1.06 mm for Group II was achieved. The mean gain in vertical attachment levels was more in Group I than in Group II. The mean change in vertical CAL between baseline and 6 months (intragroup) in Group I and Group II was statistically significant (P < 0.05).

Table 4 shows the individual values and mean vertical clinical attachment for Group I and Group II at baseline and 6 months postoperatively.

Furcation defect depths [Table 5] and radiographic bone levels showed insignificant difference and the results between the two treatment modalities were found to be statistically insignificant. The gain in the depth of furcation defect was more with Group II sites than with Group I sites. The mean change in the depth of defect between baseline and 6 months postoperatively (intragroup) in Group I and Group II was statistically significant (P < 0.0001).

Table 5

Comparison of depth of furcation defect between Group I and Group II at baseline and 6 months postoperatively

Table 6 shows the individual values of furcation defect area (in mm2) between Group I and Group II at baseline and 6 months postoperatively.

Table 6

Comparison of values of furcation defect area (in mm2) between Group I and Group II at baseline and 6 months postoperatively

The change in bone levels was not significant (P > 0.05) for both groups. The mean change in the depth of the defect between the baseline and 6 months postoperative values (intragroup) in Group I and Group II was statistically significant (P < 0.05).

The mean gain in radiographic bone level values for the Group I sites was 0.78 mm and for the Group II sites was 0.85 mm. Hence, the gain in bone levels was more with Group II than with Group I. The difference in the radiographic bone levels between Group I and Group II (intergroup) at baseline and at 6 months postoperatively was not significant (P > 0.05) [Table 7].

Table 7

Comparison of radiographic bone level (CEJ-BOD) in mm between Group I and Group II at baseline and 6 months postoperatively

The mean defect fill in Group I and in Group II was statistically insignificant (P > 0.05) [Table 8].

On analyzing the results, it was seen that both the groups, Group I and Group II, showed a significant reduction in PD, significant gain in CAL, and significant linear bone fill at baseline and 6 months postoperatively.

At the end of 6 months, Group II showed a statistically significant reduction in horizontal PD when compared to Group I. Group I showed more gain in vertical CAL than Group II (P < 0.05). Group II sites showed a statistically significant gain in horizontal CAL when compared to Group I sites (P < 0.05).

At 6 months postoperatively, Group I and II sites showed a statistically significant reduction in the depth of furcation defect (furcation bone fill) (P < 0.05).

When the mean reduction in defect area was calculated, Group II sites showed a statistically significant reduction in the defect area. The vertical defect fill mean values were statistically insignificant in both Group I and Group II.

DISCUSSION

Treatment of molar furcation defects remains a considerable challenge in clinical practice. The degree of success in the management of furcation involvement is highly variable and inversely related to the initial probing depth measurements in these lesions.[10] Several treatment approaches to obtain furcation fill have been used with varying success. Kenney et al.[11] showed coherent improvement in all of the clinical linear measurements while treating with porous HA, while Hom-Lay Wang et al.[15] reported that the placement of type I bovine collagen membrane during surgery on class II furcations resulted in significant clinical improvement. The first report of a human tooth treated according to the principle of GTR was presented by Nyman et al.[9] Lekovic et al.[16] also demonstrated that use of these materials has shown periodontal regeneration in class II furcation defects. The present study was thus conducted to assess the efficacy of resorbable GTR membrane and porous HA bone graft in the treatment of mandibular class II furcation defects. The evaluations were performed 6 months after surgery because most clinical changes occur within this period.

Resorbable barrier membranes like the ones used in this study eliminate the need for surgical removal. Kong Mun Chung et al.[17] demonstrated that sites treated with a collagen barrier consisting of cross-linked bovine type I collagen exhibited significantly better healing in bony defects. This collagen membrane thus appears to be a useful and beneficial material for regenerative therapy in class II furcation periodontal defects.[18]

Meffert[19] showed that HA material was very well tolerated in the hard and soft tissues and did not seem to evoke any inflammatory response. Barnett et al.'s[20] studies showed that the gain in clinical attachment paralleled the osseous fill for both Freezed Dried Bone Allograft and porous HA sites. Thus, HA, like the one used in the present study, provided positive results when used in the treatment of furcation defects.

In the present study, clinical parameters like horizontal and vertical PD and CAL, as well as gingival recession were assessed between collagen membrane treated site (Group I) and porous HA treated site (Group II).

In Group I, placement of type I bovine collagen membrane resulted in decrease in furcation vertical PD, gain in vertical CAL, and significantly higher defect fill during surgery in class II furcations. These changes reflect reduction of horizontal interradicular probe penetration. The reason for this effect can be formation of either new connective tissue attachment or a long junctional epithelium between the root surfaces and the newly formed dense soft tissues. These results showed that the reformation of a connective tissue attachment was considerably favored by the placement with GTR membrane alone. Similarly, in the present study, furcation defects treated with porous HA alone, i.e., Group II, showed a coherent improvement in all of the clinical linear measurements. The results showed decrease in horizontal PD and gain in horizontal attachment levels and vertical defect fill (CEJ to the base of the defect). This indicated that the fill of bony defects was accompanied by a concomitant improvement in probable attachment level and pocket depth. These results are in agreement with the results observed in a similar study by Kenney et al.[11] who achieved a reduction of 2.08 mm, which was statistically significant.

The gain in clinical attachment paralleled the osseous fill for porous HA sites. This suggested that the clinical attachment gain was a direct result of the increased bone repair. It can only be speculated that the synthetic particles have a “bone matrix maintenance” influence on the crestal bone, which allows regeneration of this bone, if it does indeed resorb, and possibly further allows the bone to grow around any adjacent particles.

In the present study, depth of the furcation defect, area of the defect, and radiographic bone level were used as the radiographic parameters. This was similar to the report of Jacob Horwitz et al.,[21] who supported that radiographic parameters measuring bone levels were found to be reliable in evaluating hard-tissue changes in class II furcation defects. The gain in the depth of defect, the mean change in the area of defect, and improvement in defect fill were statistically significant for both groups[22] and were similar to the reports by Vijay Pruthvi et al.[2] and Kenney et al.,[11] respectively.

In the present study, when comparing the baseline and final data for the parameters measured between the two groups, there was a greater mean reduction in vertical probing pocket depth and more V-CAL in Group I than Group II. This finding is in accordance with the study reports of Lekovic et al.[16] who found significant reduction in pocket depths with GTR procedure. Similarly, it was found that Group II promoted a more significant horizontal probing pocket depth reduction, gain in H-CAL, and reduction in gingival recession than group I, which are in agreement with the results of Kenney et al.[11] When comparing the two groups, furcation defects treated with GTR membrane and bone graft showed a gain in vertical bone fill.[23] Thus, gain in bone fill was observed for both the treatments groups after 6 months, but statistically insignificant difference was found when this gain was compared between these two treatments.

In conclusion, within the limits of this study, both the treatment modalities, namely, GTR membrane and bone graft, are beneficial for the treatment of periodontal mandibular class II furcation defects.[23]