Abstract
The use of platelet rich plasma (PRP) gel in combination with torus mandibularis offers a potentially useful treatment for periodontal osseous defects. Whether this combination enhances the outcome of periodontal regenerative therapy is not known. This study compared the effectiveness of torus mandibularis bone chips alone and when combined with autogenous PRP gel in treating periodontal osseous defects. 24 sites from 12 patients were selected using a split mouth design and determined by a double-blind, randomized, controlled clinical trial. Both sites received a full-thickness mucoperiosteal flap; one intrabony defect was filled with torus mandibularis bone chips alone and the other with torus mandibularis bone chips mixed with PRP gel. There was a 57% gain in the clinical attachment level and 60% reduction in the probing depth for torus mandibularis alone compared to 72% and 68% for sites treated with torus mandibularis and PRP gel ( p ≤ 0.01). There was a statistically significant difference in the bone dentistry and the marginal bone loss at sites with PRP gel compared to those without gel ( p ≤ 0.01). The use of mandibular tori as autogenous bone graft combined with PRP gel showed a significant improvement in the clinical outcome of periodontal therapy than mandibular tori alone.
Periodontal therapy is directed towards controlling the infection and regenerating the lost supporting structures. Periodontal regeneration refers to the restoration of supporting tissues of the teeth such as bone, cementum, and periodontal ligament to their original healthy levels before periodontal tissue distraction has occurred. Over the last decades different modalities of regenerative treatment have been developed and applied clinically. The positive effects of bone grafts and bone substitutes on the outcome of periodontal regenerative procedures are well documented.
Historically, autografts were the first bone replacement grafts to be reported for periodontal applications. Allogenic freeze-dried bone was introduced to periodontics in the early 1970s, while demineralized allogenic freeze-dried bone gained wider application in the late 1980s. The introduction of xenografts and alloplasts for periodontal use occurred at the same time. Autogenous bone grafts are considered the gold standard graft material for reconstruction procedures; they are non-immunogenic and contain osteoblasts and osteoprogenitor stem cells, which are capable of proliferating. These grafts are osteoinductive. The evidence that freeze-drying markedly reduces the antigenicity and other health risks associated with fresh frozen bone, as well as the favourable results obtained in field trials with freeze-dried bone allografts, have led to the extensive use of freeze-dried bone allografts in the treatment of periodontal osseous defects. The morbidity and limited availability associated with autografts, along with the potential for disease transmission, immunogenic response, and variable quality associated with allografts, have led to a variety of alternative materials.
Bone exostoses and tori are localized peripheral overgrowths of bone that arise from the cortical plate and sometimes from the spongy layer due to some unknown cause. Although the aetiology is unknown, a hereditary basis is suspected. These developmental anomalies are not pathologically significant, and frequently develop in skeletal jaw. In this respect, different types of exotoses have been described; torus palatinus and torus mandibularis are two of the most common intraoral exostoses. The other types of exostoses such as buccal or palatal exostoses are less commonly encountered.
Torus mandibularis which has reportedly been usually bilaterally is located in the lingual surfaces of the cusped/premolar area of the mandible and superior to the mylohyoid ridge. The lingual tori are unnecessary bony extensions, which may limit tongue space and create phonetic difficulties. Therefore, the tori may require surgical removal for prosthetic reasons. Removal of these exostoses can also assist with flap adaptation during periodontal surgery.
A different approach to periodontal regeneration is the use of polypeptide growth factors (PGFs). These biologic mediators have the ability to regulate cell proliferation, chemotaxis, and differentiation. Among the known PGFs, platelet-derived growth factor (PDGF) and TGF-b have been studied the most extensively. PDGF has the primary effect of a mitogen, initiating cell division. Recombinant human PDGFBB, in combination with recombinant insulin-like growth factor-1, has been shown to exert a favourable effect on periodontal regeneration, as measured by the gain in clinical attachment level and osseous defect fill in humans. Upon activation, TGF-b facilitates wound healing under inflammatory conditions. PGFs, such as PDGF and TGF-b, are known to be abundant in the a-granules of platelets.
The use of platelet-rich plasma (PRP) is a convenient and economical approach to obtain autologous PDGF and TGF-b. It involves the sequestration and concentration of platelets in plasma with subsequent application of this preparation to wound-healing sites. It has been shown that the application of PRP to the wound-healing site increases the concentration of platelets (and theoretically of PDGF and TGF-b) by up to 338%. The use of PRP and torus mandibularis in combination offers a potentially useful modality for treating periodontal osseous defects. It is unknown whether a combination of these materials would enhance the outcome of periodontal regenerative therapy. This study was carried out to compare the effectiveness of using the torus mandibularis bone chips alone and when combined with autogenous PRP gel in treating intrabony defects in patients with chronic periodontitis by analyzing the clinical and radiographic parameters.
Materials and methods
12 patients (7 males and 5 females with an average age of 41.4 ± 2.61 years) with chronic periodontitis were selected to participate in this randomized split mouth design study. The present clinical study was designed as a controlled clinical trial with a parallel design. Patients were selected from the outpatient clinic at University of Dammam, College of Dentistry, Kingdom of Saudi Arabia. Patients selected for this study were free from any systemic diseases, non-smokers, not pregnant (female cases), had a good level of oral hygiene, and had infrabony 2 osseous walls defect with a probing pocket depth (PPD) ≥ 6 mm and clinical attachment level (CAL) of ≥5 mm. 24 sites were selected by using a split mouth design for each patient determined randomly through a biased coin randomization. For each patient; one site (group I) received a full-thickness mucoperiosteal flap and filling the infrabony defect with torus mandibularis bone graft alone. The other site (group II) received a full-thickness flap and filling with torus mandibularis bone graft mixed with PRP gel.
Each patient was prepared for surgery with an initial phase of therapy including oral hygiene instructions and scaling and root planning. Approximately 4 weeks after initial therapy, patients were re-evaluated to assess clinical parameters and plaque control. All subjects had to achieve good oral hygiene (<20% O’Leary plaque index) prior to progressing to the surgical phase of therapy.
Written informed consent was obtained from the patient prior to surgical treatment and the protocol was reviewed and approved by the Ethical Committee of the College of Dentistry, Dammam University, Kingdom of Saudi Arabia.
The following clinical parameters were assessed (by AA, examiner) at base line, 3, 6, 9 and 12 months postoperatively using the same periodontal probe (NUC-15 probe; Hu-Friedy, Chicago, IL, USA): gingival index (GI), PPD and CAL. Blinded clinical and radiological assessments were performed at base line and after 3, 6, 9 and 12 months. Six points per tooth were assessed and the highest was recorded.
Bone graft collection
A full-thickness mucoperiosteal flap was elevated for torus mandibularis access and for bone graft collection ( Fig. 2 ). Vertical releasing incisions were performed if necessary for better access. Surgical burs #701 and 702 in a slow speed handpiece were used under copious irrigation with sterile normal saline (0.9% NaCl) to remove the torus mandibularis. Bone grafts were collected with a bone trap (Omniasurg ASP 100; Omnia srl, Fidenza, PR, Italy). The trap filter was equipped with a removable internal mesh with a pore diameter of 300 μm. Two distinct systems were used for aspiration and bone collection. One system was used for the control of saliva and bleeding and kept at a distance of 1.5 cm from the osteoctomy site. The other system was sterile and disposable, and comprised a filter for collecting bone chips and a plastic suction tube. The latter was held as close as possible to the osteoctomy site in order to collect the bone debris and reduce the aspiration of saliva. The collected tissues were placed in a sterile bone well containing sterile saline solution at room temperature and covered with a cap in order to minimize the risk of contamination ( Fig. 3 ). After preparation of the reception site, the excess of saline solution was removed and the collected materials alone were used to fill the intraosseous defects in group I. In group II, the collected materials were mixed with PRP gel and used to fill the intraosseous defects. The flaps were closed with absorbable vicryl type surgical thread (3/0) and simple interrupted sutures.
Bone graft collection
A full-thickness mucoperiosteal flap was elevated for torus mandibularis access and for bone graft collection ( Fig. 2 ). Vertical releasing incisions were performed if necessary for better access. Surgical burs #701 and 702 in a slow speed handpiece were used under copious irrigation with sterile normal saline (0.9% NaCl) to remove the torus mandibularis. Bone grafts were collected with a bone trap (Omniasurg ASP 100; Omnia srl, Fidenza, PR, Italy). The trap filter was equipped with a removable internal mesh with a pore diameter of 300 μm. Two distinct systems were used for aspiration and bone collection. One system was used for the control of saliva and bleeding and kept at a distance of 1.5 cm from the osteoctomy site. The other system was sterile and disposable, and comprised a filter for collecting bone chips and a plastic suction tube. The latter was held as close as possible to the osteoctomy site in order to collect the bone debris and reduce the aspiration of saliva. The collected tissues were placed in a sterile bone well containing sterile saline solution at room temperature and covered with a cap in order to minimize the risk of contamination ( Fig. 3 ). After preparation of the reception site, the excess of saline solution was removed and the collected materials alone were used to fill the intraosseous defects in group I. In group II, the collected materials were mixed with PRP gel and used to fill the intraosseous defects. The flaps were closed with absorbable vicryl type surgical thread (3/0) and simple interrupted sutures.
PRP gel preparation
10 ml venous blood was obtained from each patient to prepare 2 ml PRP gel. The blood was drawn into 10 ml sterile vacutainer tubes containing 0.5 ml sodium citrate. The tubes were centrifuged at 200 × g for 20 min. All plasma were transferred to a 15 ml conical sterile polypropylene tube and centrifuged at 400 × g for 10 min. The upper part of the preparation had the platelet-poor plasma and the lower part the PRP. At the time of PRP application, a mixture of 10% calcium chloride and bovine thrombin was added to initiate coagulation. The resulted PRP gel was added to the torus mandibularis autogenous bone graft ( Figs. 4 and 5 ).
Periodontal surgical procedure
The same surgeon performed all procedures (KH). Intra-sulcular incisions were made, full-thickness mucoperiosteal flaps were raised vestibularly for defect access and granulation tissue removal at both sides of the teeth ( Fig. 1 ). Vertical releasing incisions were performed only if necessary for better access or to achieve better closure of the surgical sites. All granulation tissues were debrided from the root surfaces and the defects. One site was treated with torus mandibularis alone and the other site with torus mandibularis mixed with PRP gel. The graft was delivered to the bony defect with a spatula and added in an incremental fashion. Light pressure was used to maintain the space between the graft particles to allow neovascularization of the site. The defect was filled or slightly overfilled ( Fig. 6 ) to maximize regeneration without compromising flap closure or vascular supply. A bioabsorbable collagen membrane (15 mm × 20 mm, ACE Surgical supply, Inc., USA) was trimmed and adapted so that it covered the defect and extended at least 3 mm beyond its margins. The flaps were closed and sutured with interrupted sutures (3/0 absorbable vicryl suture). All patients received antibiotics for 1 week (amoxicillin 500 mg/3 times/day) and rinsing with 0.2% chlorhexidine solution twice daily. All patients were re-called after 3, 6, 9 and 12 months for clinical and radiographic assessment.
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