A furcation lesion is defined as ‘‘the pathologic resorption of bone in furcation area of a multirooted tooth where the roots diverge’’.¹ The furcation area can be divided into three parts: fornix (roof), area of root separation and furcation crotch area (immediately coronal to the root separation). Other contributing morphological factors such as root trunk length, root concavities, fornix width, cervical enamel projections, contribute not only in pathogenesis of the lesion but also lead to difficult instrumentation.²

Various treatment modalities are proposed, involving either maintaining existing furcation or removing the furcation and regenerating the lost attachment apparatus which is achieved by natural or synthetic bone graft materials such as autogenous, allogenous grafts, xenografts and alloplasts.^3,4

Due to the limitation of autografts and xenografts, synthetic alloplastic bone grafts are used broadly.

Alloplastic materials are synthetic, inorganic, biocompatible and easily available. They act as structural porous scaffolds for clot formation, angiogenesis and remodeling of bone by pre-existing osteoblasts cells that support bone formation and new connective tissue attachment results in reconstruction periodontal osseous defects.

Among alloplastic bone grafts, bioceramics are used widely. Bioceramics are ceramic products or components utilized in medical and dental applications; they may be resorbable (tricalcium phosphate), non-resorbable (alumina, zirconia), bioactive (bioactive glasses, hydroxyapatite and glass-ceramics).

Bioactive calcium phosphosilicate glass (BG) developed by Hench and Andersson (1993), is an alloplastic, synthetic bone grafting material composed of calcium ions, sodium ions, phosphate and silicon dioxide.⁵ It is available in different morphological forms like particulate and putty. The particulate form is available in 300-355 μm and 90-710 μm of two different particle sizes. It is osteoconductive and osteopromotive as it acts as a biocompatible surface for osteogenic stem cells to form new bone.⁶ When graft particles come in contact with interstitial fluids, they form a hydroxycarbonate apatite layer onto which organic ground substances and osteoblasts get incorporated and release organic constituents, followed by organic matrix mineralization.⁷

Hydroxyapatite (HA) biomaterials simulate bone in their chemical composition {Ca₁₀(PO₄)₆(OH)₂} and have a calcium-to-phosphate ratio of 2:3. These are available in various forms like cement, nonporous, porous and nano-sized. These are biocompatible materials with little inflammatory response, leading to deposition of bone crystals directly onto the surface of implanted apatite particles.⁸ Synthetic nano-crystalline hydroxyapatite (NHA) paste contains about 65% water and 35% nanostructured apatite particles.

Many comparative studies are being done in the quest to find the regenerative potential of various new bone graft materials but data related to comparative regenerative potential of the bioactive calcium phosphosilicate and nano-crystalline hydroxyapatite graft in the treatment of class II furcation defects is lacking. Hence the purpose of this study was to evaluate and compare the efficacy of these grafts in the treatment of class II furcation defects.

This study was a 6-month randomized controlled study which was designed and conducted in the Department of Periodontology and approved by the institutional ethical committee. The patients were informed about the study duration and the benefits in detail. Written informed consent was obtained from the patients willing to participate in the study. A total 24 patients within the age group of 30-50 years, having class II furcation defect in either maxillary or mandibular posterior teeth with ≥3 mm horizontal probing depth, ≥3mm clinical attachment loss and ≥5 mm of vertical probing depth in mid-furcation area were included in this study. The selected patients were randomly allocated into three groups by computer-generated randomization.Patients with a history of periodontal therapy 6 months before the study, history of any systemic diseases, allergic to any material used in dentistry, all types of tobacco users, immuno-compromised patients, pregnant or lactating mothers, teeth with ≥Grade I mobility and non-vital teeth were excluded from the study. The probing depth and clinical attachment level were standardized in a selected site by using a surgical stent (Figures 1 and 2).

Brushing technique was standardized for all patients in three groups (Modified Stillman Brushing Technique). Scaling and root planning (SRP) was performed in all selected patients.

 

 Figure 1. Horizontal probing depth measured with Naber’s probe by using surgical stent

Radiographic evaluation

Standardized radiographs (using XCP film holder and RVG grid) were taken using long cone paralleling technique and customized bite blockat baseline and 6 months postoperatively to evaluate percentage bone fill. The radiograph was stored in JPEG format and transferred to Image J software, which was designed by the National Institute of Health (NIH) for the image analysis. The cementoenamel junction (CEJ), the base of the furcation defect (FD), and the furcation fornix (Fx) were located on the image. Using the line connector tool, lines were drawn¹² (Figure 3).

 

 

Depth of furcation defect = (CEJ-FD LINE) – (Fx-CEJ LINE)

 Figure 3. Radiographic evaluation of the depth of furcation defect

CEJ line: A line drawn from the mesial to the distal CEJ.

Point A: Tangent drawn from mid-point of the fornix (Fx) to the CEJ.

Point B: Fornix of the furcation (Fx).

Point C: Base of furcation defect (FD).

Fx-CEJ line: (AB line) Distance from Fx (point B) to CEJ line perpendicular to the CEJ line (point A).

CEJ-FD line: (AC line) Distance from CEJ to base of furcation defect (FD) (point C) perpendicular to the CEJ line (point A).

(AB¹line): Post-operative distance from Fx to CEJ line perpendicular to the CEJ line (point A).

(AC¹line): Post-operative distance from CEJ to base of furcation defect (FD) perpendicular to the CEJ line (point A).

Arithmetic determination

Pre-operative furcation depth = AC-AB

Post-operative furcation depth = AC¹ – AB¹

Percentage bone fill = (Pre-operative furcation depth – Post-operative furcation depth) × 100

Patients were re-evaluated 2 weeks after phase I therapy. Patients having ≤1.0 plaque index inference only were considered for surgery. Then the patients were allocated to three groups as assigned by computer-generated randomization to receive treatment.

Test group I: Treated with open flap debridement (OFD) + NHA bone graft and Test Group II: Treated with OFD + BG bone graft and Control Group: Treated with OFD alone (Figure 4).

 

BG – bioactive calcium phosphosilicate glass; NHA – nanocrystalline hydroxyapatite; OFD – open flap debridement.

 

Figure 4. Study design

The extraoral surgical area was swabbed with 5% w/v povidone-iodine for 90 seconds. After profound anesthesia, a crevicular incision was made around the neck of teeth from the base of sulcus to crest of alveolar bone on both buccal and palatal or lingual gingiva using bard parker (B.P.) blade no. 12. The full-thickness flap was reflected, followed by removal of granulation tissue debridement with area specified Gracey curettes. If any bony spicules were present in furcation area, odontoplasty and osteoplasty was performed with air-rotor handpiece and sugarmann bone file respectively. After granulation tissue debridement, the furcation defect was filled using appropriate graft material according to randomization. The flaps were repositioned and sutured with direct loop interrupted sutures with 4-0 black-braided silk suture and a non-eugenol periodontal dressing was placed (Figure 5).

 Figure 5. Steps of surgical procedure

Antibiotics and analgesics (capsule of amoxicillin 500 mg three times daily for 5 days and tablet of ibuprofen 400 mg three times daily for 3 days) were prescribed. Oral hygiene maintenance instructions were given following surgery. Adjunctive plaque control in the form of chlorhexidine gluconate concentration 0.2% twice daily for 14 days was advised. Periodontal dressing and sutures were removed 14 days after surgery. Clinical evaluations were done after 3 and 6 months and radiographic evaluation was done at 6 months (Figure 6).

 

Statistical analysis

The data was evaluated using means and standard deviations of the measurements per group for statistical analysis (SPSS 22.0 for windows; IBM Corp., Armonk, NY, USA). For each assessment point, data were statistically analysed using one-way ANOVA test. The intergroup comparison between the three groups was determined using paired t-test and ANOVA. The level of significance was set at p <0.05.

Clinical parameters

All three groups showed a statistically significant reduction in all clinical parameters (plaque index, gingival index, vertical probing depth and horizontal probing depth) and gain in clinical attachment level from baseline to 6 months (Tables 1 and 2). The mean gain in clinical attachment level at baseline for test group I was 7.75±0.71 mm, changed to 4.38±0.92 mm and 3.63±0.92 mm, for test group II 7.25±0.89 mm, 4.25±0.71 mm and 3.50±0.76 mm and control group 7.50±0.93 mm, 5.63±0.74 mm and 4.75±0.71 mm at 3 months and 6 months respectively (Figures 7 and 8). On intergroup comparison, there was no statistically significant difference between the test group I and test group II. However, there was a statistically significant difference seen in clinical parameters in both test groups in comparison with the control group.

 

 Table 2. Intergroup changes in clinical parameters at different time intervals

 

 

 

 Figure 7. Mean changes in plaque index and gingival index among the three study groups at different time

 

 Figure 8. Mean changes in horizontal probing depth (HPD), vertical probing depth (VPD) and clinical attachment level (CAL) among the three study groups at different time intervals

 

Radiographical parameters

There was a statistically significant reduction in furcation defect (FD) and percentage bone fill from baseline to 6 months in all three groups. The mean reduction in FD level with the standard deviation in Test group I, Test group II and Control group was 1.82±0.61 mm, 1.76±0.54 mm, 1.04±0.19 mm (p=0.0001). There was no statistically significant difference between both the test groups from baseline to 6 months (p=1.00). However, there was a statistically significant difference in the reduction of furcation defect in both Test groups at 6 months in comparison to the Control group (p=0.005 and p=0.001) (Table 3, Figure 9).

 

 

 

Both the Test groups and Control group showed percentage bone fill from baseline to 6 months. The percentage bone fill was: for Test group I 64.32%, for Test group II 62.43% and for Control group 33.42%. This change was statistically significant in the percentage bone fill from baseline to 6 months in both test groups as compared to the control group (p<0.005). There was a statistically insignificant difference seen in both the test groups (p=1.00) (Table 3, Figure 10).

 

 

In the present study, there was a reduction in plaque and gingival index score from baseline to 6 months, attributed to the fact that only those patients who showed maintenance of optimum oral hygiene were included in the study and maintained throughout the study period by reinforcement of plaque control measures and oral hygiene instructions at various recall periods. This is per Ong MAet al. (1998).⁹ Long-standing attainment through regenerative procedures is directly correlated with good plaque control. Hannula J et al. (2001)¹⁰ and Quirynen M et al. (2001)¹¹ concluded that intraoral transmission and cross infection of pathogenic bacteria from one niche to other niches can lead reinfection and recurrence of the disease. So, in the present study, full mouth plaque score and gingival score were evaluated.

There was a statistically significant difference seen in vertical probing depth, horizontal probing depth and gain in clinical attachment level in favor of bone replacement groups as compared to OFD groups in defect fill of class II furcation. This is per Mellonig JT (1992)¹² and Camargo et al. (2000).¹³

Radiographic parameters

The group with OFD alone showed a statistically significant reduction in the depth of furcation defect and percentage bone fill per Chitsazi MT (2007)¹⁴ and Forum et al. (1998).¹⁵ Renvert et al. (1985)¹⁶ found a significant amount of bone fill of 0.7 mm in OFD treated sites. This may be due to reduced inflammation to surgical site and formation of new coronal attachment. There was also statistically significant resolution of defect from baseline to 6 months in OFD + BG group concurring with Humagain M et al.,¹⁷ Zamet et al. (1997)¹⁸ and Yukna et al. (2001).¹⁹ This may be due to the silica-rich layer provided by hydroxycarbonate-apatite precipitation and crystallization, which results in increased osteoblast cell proliferation, thus allowing rapid bone formation. There was also a statistically significant resolution of defect from baseline to 6 months in the OFD + NHA group (1.82±0.61mm). This is per Bayani M et al. (2017)²⁰ who described that the nanocrystal probably enhances the solubility of graft material needed for resorption of bone by osteoblasts.

On intergroup comparison, there was a statistically significant difference in depth of furcation defect reduction in the OFD group in comparison to the OFD + NHA and OFD + BG groups (p<0.05). The results of the present study are generally in agreement with the study by Zamet et al.¹⁸ and Kenney et al.²¹ There was no statistically significant difference between both test groups, maybe because of an osteostimulatory effect of BG and nanoparticle size of NHA inducing protein adhesion.

On intragroup comparison, the control group showed a percentage bone fill from baseline to 6 months of 33.42%. This is in agreement with Mistry S et al. (2009)²² due to initial colonization by gingival epithelial cells resulting in the filling of defect with connective tissue. Both test groups show osseous fill about 64.32% and 62.43%. This is per a study by Khamboj M et al. (2016).²³ On intergroup comparison, there was a statistically significant percentage bone fill in test groups from baseline to 6 months as compared to the OFD alone group. This is per studies by Froumet al.²⁴Aichelmann-Reidy and Yukna (1998)⁷ have shown that OFD procedures alone produce 10-30% osseous fill in periodontal defects as compared with a mean defect fill of 60-70% that can be anticipated with bone replacement grafts. There was a statistically insignificant difference seen in percentage bone fill from baseline to 6 months in both test groups, in agreement with Nasret al. (1999)²⁵ who concluded that both materials are osteoconductive. BG also acts as barrier membrane retarding epithelial downgrowth and NHA acts as osteophilic material.

Limitation

The present study should have histological, microbiological and biochemical analysis to ascertain specific periodontal pathogens affected and levels of matrix metalloproteinases to assess the efficacy of bone graft. A shortcoming could have arisen due to the two-dimensional representation of a three-dimensional structure and lack of assessment of furcation defect width to estimate the accurate bone fill in the furcation area. A longer post-operative evaluation and a larger sample size would provide a better assessment of the results of the various therapies.

The study concluded that NHA and BG bone graft material have regenerative potential. This may be due to their osteoconductive property directly or indirectly binding to osteogenic cells to the laid down organic matrix which undergoes mineralization. Due to the reduction in furcation depth and gain in percentage bone fill along with open flap debridement, they can be used in the treatment of class II furcation defects. The materials appeared safe and well-tolerated by patients. However, longitudinal studies with histological evaluation and biochemical analysis using a larger sample size are required to ascertain the effect of nanocrystalline hydroxyapatite bone graft and bioactive calcium phosphosilicate bone graft in the treatment of class II furcation defects.

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