| Abstract|| |
Background and Objectives : Bone grafting is the most common form of regenerative therapy. Several bone substitutes have been used in clinical periodontal therapy to encourage bone formation. The present study has been undertaken to evaluate the efficacy of hard tissue replacement polymer (Bioplant® HTR® ) as a bone graft material in the treatment of interproximal vertical bony defects in human beings, both clinically and radiologically.
Materials and Methods : Five chronic periodontitis patients were selected with 16 sites assigned randomly into control (open debridement alone) and experimental (open flap debridement plus Bioplant® HTR® ) groups. Clinical measurements like plaque index (PI), gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), gingival margin position (GMP) assessment was done at 0, 3 and 6 months and radiographic assessment at 0 and 6 month. Statistical analysis was performed using Wilcoxon's signed Rank test and Mann-whitney U-test.
Results : There were statistically no significant (P=1.00) changes in Plaque index and Gingival Index scores in both the groups from baseline to six months post surgery. Statistically significant (P<0.05) reduction in Probing Pocket Depth was seen on comparison between the groups. In relation to the hard tissue changes, significant results were seen with respect to change in alveolar crest and percentage of original defect resolved. Comparison of results from six to 12 months following similar treatments showed no significant differences or advantages to having a clinical evaluation period longer than 6 months post surgically (Yukna 1999).
Interpretation and Conclusion : Bioplant® HTR® material is a biocompatible, easy to handle and a beneficial grafting material for the treatment of periodontal osseous defects.
Keywords: Bioplant® HTR® , HTR polymer, bone substitutes, grafts, vertical defect
|How to cite this article:|
Prakash S, Sunitha J, Abid S. Evaluation of HTR polymer (Bioplant® HTR® ) as a bone graft material in the treatment of interproximal vertical bony defects: A clinical and radiological study. Indian J Dent Res 2010;21:179-84
The treatment of periodontal disease has several major therapeutic goals. As stated in the 1989 proceedings of a world workshop on Clinical Periodontics, "The immediate goal is to prevent, arrest and control or eliminate periodontal disease, however, the ultimate goal of periodontal therapy is to restore the structures, integrity, and function of tissues that have been lost as a result of inflammatory periodontal disease.  Traditional periodontal therapy such as scaling, root planing and gingival curettage are highly effective in reducing the likelihood of periodontal disease progress, but has an extremely limited capacity to stimulate regeneration. Though the reconstruction of the periodontium destroyed by periodontitis is considered a major challenge in periodontal therapy, recently a large number of human and animal studies have shown a greater promise to restore the lost alveolar bone through the use of bone grafts.
|How to cite this URL:|
Prakash S, Sunitha J, Abid S. Evaluation of HTR polymer (Bioplant® HTR® ) as a bone graft material in the treatment of interproximal vertical bony defects: A clinical and radiological study. Indian J Dent Res [serial online] 2010 [cited 2021 May 8];21:179-84. Available from: https://www.ijdr.in/text.asp?2010/21/2/179/66630
Bone grafting is the most common form of regenerative therapy and is usually essential for restoring all types of periodontal supporting tissues. The first recorded attempt to use alveolar bone graft was Dutch surgeon Job Van Meekren. However, the first use of bone grafts in the periodontal therapy is credited to Hegedus.  Since human bone graft material is limited, synthetic grafts have been derived to substitute and/or augment human bone material. Among such substitutes are particles composed of hydroxyapatite, tricalcium phosphate and porous hydroxyapatite. In general, these synthetic bone substitutes have not enhanced new attachments, but rather served as well-tolerated fillers. 
Bioplant® Hard tissue replacement (HTR®) is a synthetic bone material. These polymers have been used in various forms to make contact lenses, prosthetic heart valves, femoral head prostheses, orthopedic bone cements, spinal fusion procedures, and implant devices for sustained release of medications.  Its efficacy is the result of an exceptional combination of physical and chemical properties that all together make it osteopromotive. It has a microporous structure that allows the new bone to biologically attach to the HTR bead. It forms a matrix, replaces the removed bone structure temporarily and in the same time promotes the new bone growth.  One year after the treatment the Bioplant HTR® filled defect consists of approximately 90% genuine secondary bone. The new secondary bone is of exceptional quality because it attracts primarily those cells that form osteoblasts which are responsible for formation of dense lamina bone.
Szabo et al,  conducted a long term (five years) follow-up study of Bioplant HTR® synthetic bone in the human periodontal defects and reported a complete regeneration in about five years time. Murray  conducted a study on clinical applications of HTR polymer in periodontal regenerative surgery. He observed that the non-resorbable radiopaque particles of HTR polymer remain visible radiographically but ultimately become incorporated into a radio-dense matrix as the healing progresses. Shahmiri et al,  studied the clinical response of the use of the HTR polymer implant in human intrabony lesions. At the end of the 12 months, pocket reduction responses were similar both at control and implanted sites.
Hence, the present study was undertaken to evaluate HTR Polymer (Bioplant® HTR®) as a bone graft material in the treatment of interproximal vertical bony defects in patients with chronic periodontitis.
| Materials and Methods|| |
The patients for this study were selected from the outpatient department of Periodontics, College of Dental Sciences, Davangere, Karnataka. Patients of both the sexes were included in the study. Written informed consent was obtained from participants who voluntarily agreed and the ethical clearance was obtained from the ethical committee of College of Dental Sciences. Davangere Karnataka.
- Patients diagnosed as suffering from chronic periodontitis
- Patients in age group of 35-55 years
- Patients with at least two interproximal periodontal pockets, measuring ≥ 6mm, with radiographic evidence of vertical bone loss
- Patients who were non-smokers
- Patients who had not taken any type of periodontal therapy prior to six months of initial examination
- Patients with any history of systemic disease, or compromising medical condition
- Pregnant and lactating women
- Patients who had taken antibiotics six months prior to the study
- Patients allergic to tetracycline and /or chlorhexidine
- Patients who clench and grind teeth (overt bruxism)
- Patients showing unacceptable oral hygiene during phase I periodontal therapy
The study was a randomized clinical trial and a total of 16 sites were selected for the study; of them, eight control and eight experimental sites were selected randomly and treated according to split mouth design. Control sites were treated with open flap debridement (OFD) and experimental sites were treated with open flap debridement (OFD) and placement of Bioplant® HTR® bone graft.
The following clinical parameters were recorded at baseline, three and six months post surgery.
- Plaque Index (Silness and Loe, 1964)
- Gingival Index (Loe and Silness, 1963)
- Probing pocket depth
- Clinical attachment level
- Gingival margin position
Bioplant HTR® (Hard Tissue Replacement) is a synthetic bone material. Biocompatible, nonresorbable, osteoconductive matrix for regenerative bone growth.  HTR is a patented original material composed of: 
- Poly methyl methacrylate (PMMA), porous spherical particles providing the strength
- Poly hydroxyethyl methacrylate (PHEMA), hydrophilic coating of the particles, providing ease of handling
- Calcium hydroxide / carbonate, outermost layer, coating the particles and interacting with bone, providing the osteogenic potential
- Additional thin layer of barium sulfate for radio-opacity
HTR-40 micromesh matrix (particle size approximately 500 microns in diameter) in granular bead form was used in this study, which was available as Bioplant® HTR® 0.25 grams in curved syringe with patented biotip, prefilled and packaged sterile.
All the selected patients, following an initial examination and treatment planning discussion, were given detailed instructions about self-performed plaque control measures and were subjected to phase-I periodontal therapy. Selective grinding in cases with trauma from occlusion was considered. Two weeks after phase-I therapy the oral hygiene status and tissue response was evaluated using plaque index  and gingival index. 
On completion of the baseline examination, the infrabony defects were randomly assigned as experimental or control sites. Patients were asked to rinse the mouth with 10 ml. of 0.2% chlorhexidine digluconate solution. The extraoral surfaces of the patient were swabbed with 5% povidone iodine solution. The operative site was anesthetized with 2% Xylocaine HCI with adrenaline (1:80,000) using block and infiltration techniques. The crevicular and interdental incisions were given using the Bard Parker knife with blade number 12 and 11 respectively.
A full thickness mucoperiosteal flap was reflected using the periosteal elevator taking care that the interdental papillary tissue was retained as far as possible. After reflection of the flap and exposure of osseous defect, a thorough surgical debridement of soft and hard tissue was done using the area specific Gracey curettes and Scissors. After completion of debridement the surgical site was irrigated copiously with 0.9% normal saline. Following isolation of the site, root biomodification was done by burnishing the root surfaces with cotton pledgets soaked in freshly prepared saturated solution of tetracycline hydrochloride at a concentration of 100mg/ml for 3-5 minutes. Root surfaces were then irrigated profusely with normal saline. Osseous defects were curetted out and the cortical walls were perforated (decortication) with a 1/2 round bur or curet tip to create intramarrow bleeding. , At the experimental site, presuturing  was done. The required quantity of HTR was transferred from the syringe to the dappen dish and moistened with sterile saline. When it became a cohesive mass, with the help of scoop end of the cumine scaler (Hu-Friedy), the material was carried into the osseous defect incrementally and carefully placed from the base of the defect coronally using a light pressure and filled up to the most coronal level of the osseous walls. HTR's hemostatic properties resulted in a clear surgical field. The mucoperiosteal flaps were repositioned and secured in place using a 3/8 circle, reverse cutting needle and 3-0 black braided silk sutures. Interrupted direct loop sutures were placed to obtain primary closure of the interdental space and the area was protected with a noneugenol (Coe-pak) dressing. All patients were prescribed systemic Doxycycline HCl 200 mg for the first day followed by 100 mg/day for another 4 days along with Nimesulide 100mg tablets were given twice daily for three days.
Postoperative instructions were given to all the patients and they were instructed to report to the department after 24 hours and then after seven days. After seven days, the dressing and sutures were removed and surgical site was irrigated with normal saline. Recall appointments were made at three months and six months. At each visit, oral hygiene instructions were reinforced and supragingival scaling was done if required.
Intraoral periapical (IOPA) radiographs were taken for each site before surgical procedure [Figure 1] and [Figure 3] and at intervals of 6 months post surgery using long cone/paralleling technique [Figure 2] and [Figure 4].
Measurement of osseous defects
Intraoral periapical (IOPA) radiographs of each site were digitized using a flat bed scanner with a scanning resolution of 600 dpi, (Umax-Astra 1220S). The scanned images, stored in JPEG format, were transferred to Adobe Photoshop 9. For measurements, connector line tool was used. The cement-enamel junction (CEJ), the base of the defect (BD) and the alveolar crest (AC) were located on the image. Using the connector line tool, two lines were drawn from CEJ to BD and also from CEJ to AC respectively. Then 1mm square grid lines were superimposed on the radiographic images. The distance between the two points of each line were measured by using the superimposed square grid lines. The depth of the osseous defect was obtained by subtracting the two measurements; by using the above method for pre and post surgical radiographs.
Changes in the clinical and radiographic parameters from baseline to six months post surgery in both experimental and control groups were analyzed by Wilcoxon's Signed Rank Test within a group (intragroup); the intergroup comparisons were made by Mann-Whitney U-Test. (non parametric tests were used due to presumed non-normality of the measurements within individual cases). For all the tests a P value of 0.05 or less was considered for statistical significance.
| Results|| |
The comparison between experimental and control groups, mean plaque index and gingival index scores showed no difference in reduction. On plaque index scores was 57 % and gingival index score was 18 % for both control and experimental groups. The mean difference in pocket depth when compared between experimental and control groups at baseline was 0.75, and at six months post surgery was 1.38, which was statistically significant (P<0.05) [Table 1]. The mean difference in clinical attachment level when compared between experimental and control groups at baseline was 0.62 which was statistically not significant (P=0.91) [Table 2]. The mean gain in clinical attachment level at six months post surgery was 1.12, which was statistically not significant (P=0.10). However, higher gain in clinical attachment level for the experimental group (31%) as compared to control group (18%) was seen. The mean difference in percentage of original defect resolved and change in alveolar crest when compared between control and experimental groups six months post surgery was 35.3% and 18% respectively, which was statistically significant (P=0.05) [Table 3].
| Discussion|| |
Periodontal treatment goals include attempts at regeneration of lost attachment. This requires new cementum formation accompanied by newly inserted functionally oriented fibers at a root site previously exposed to the oral environment. Intrabony lesions have shown such regenerative responses particularly when osseous grafts were placed into the debrided defect to enhance new attachment.  Bioplant HTR® , a bone regeneration material, is a unique combination of biologically compatible polymers that forms a nonresorbable, radio-opaque, porous matrix which stimulates the new bone ingrowth.
The present clinical study aims at the placement of a non-resorbable, microporous, synthetic bone grafting material (Bioplant® HTR® polymer), to evaluate its short-term clinical and radiological response in interproximal vertical bony defects associated with chronic periodontitis and also to compare its effectiveness to open flap debridement alone.
The mean difference in pocket depth reduction, when compared between experimental and control groups at six months post surgery, was 1.38, which was statistically significant (P<0.05). The comparison showed a higher reduction in pocket depth in the experimental group (40%) as compared to control group (25%) which correlated with the observations made by Shahmiri et al. (1992)  and Yukna (1990)  . The comparison showed higher gain in clinical attachment level for the experimental group (31%) as compared to control group (18%). This finding is in accordance with Yukna (1990). 
The amount of defect fill in the experimental group from baseline to six months was statistically significant (P<0.05) and the mean percentage of original defect resolved six months post surgery in control and experimental groups was 12.1 35.0 and 47.4 58.3 respectively. This finding is in accordance with that of Yukna. 
Six months may be considered too short a time to fully evaluate the effect of periodontal therapy, particularly that which utilizes grafting techniques. However, this time frame seems to be the standard for this type of research whether natural materials, synthetic materials or surgical debridement is the therapy provided. As comparison of results from six to 12 months following similar treatments showed no significant differences or advantages to having a clinical evaluation period longer than six months post surgically. 
In the present study, the Bioplant HTR® group showed better results than the open flap debridement (control) group in terms of both clinical as well as radiographic assessment. Though it has shown promising results on clinical and radiological evaluation in the present study, it would be inappropriate to draw definite conclusions regarding the nature of the defect fill. Additional studies to compare its efficacy with other regenerative graft materials are suggested. Histological studies of HTR polymer grafts will provide more information on this grafting material.
| Conclusions|| |
HTR combines a polymer poly methyl methacrylate (PMMA), a liquid poly hydroxyethyl methacrylate (PHEMA) and calcium in a patented process, which results in a biocompatible composite. However, the exact nature of tooth-implant interface is not understood. Radiographically, it can be concluded that the Bioplant® HTR® graft material may add to bulk of the osseous structures or may result in the formation of osseous material. The factors controlling the closure and new attachment have not yet been identified. However, research identifying factors responsible for regeneration of periodontal attachment should lead to the development of clinically predictable techniques.
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Department of Periodontics, College of Dental Sciences, Davangere
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]