Maxillary sinus floor Augmentation with Autogenous bone graft alone and Autogenous bone graft with platelet rich plasma: A Comparative Clinical Study

INTRODUCTION The placement of dental implants requires sufficient amount of bone to stabilize the implants. Implant placement in the posterior maxilla is more challenging owing to the limited quantity of bone and presence of maxillary sinus¹. The insufficient quantity of bone is due to tooth loss which results in rapid resorption of alveolar bone due to lack of intra-osseous stimulation by PDL fibers² & pneumatization of maxillary sinus that leads to close apposition of the alveolar crest, to the maxillary sinus. Autogenous bone grafts contain osteogenic, osteoinductive and osteoconductive properties including growth factors. Use of growth factors can be combined with tissue regeneration techniques and sinus floor augmentation. Platelet derived growth factor induces the differentiation of undifferentiated stem cells to osteogenic cells, decreases the postoperative bleeding, pain, increases collagen production, improves the growth of new blood vessel, reduces swelling and improves the soft tissue healing.⁴

Objectives

This study aims at the evaluation and the comparison of maxillary sinus floor augmentation with autogenous bone graft alone and autogenous bone graft with platelet rich plasma. This will be evaluated by assessing the clinical parameters such as pain, swelling, wound dehiscence, extrusion of graft material, infection and radiographic assessment of alveolar bone height on the OPG.

MATERIALS AND METHODS

A total of 20 patients were selected with edentulous area in the posterior maxilla visiting the department Oral and Maxillofacial Surgery, satisfying the following criteria.

Inclusion criteria

Patients with minimum age of 18years and above with edentulous area in the maxilla posterior to canines and who are medically fit and who are willing for the implant placement and sinus lift procedure and who can come for regular post operative follow up.

Exclusion criteria

Medically compromised patients like uncontrolled diabetes, hypertension and those with any periapical and oral pathological conditions and Patients who have undergone corticosteroid therapy or having osteoporosis, maxillary sinusitis.

Method of collection of data: A randomized prospective study is conducted in which patients are assessed under two groups, in one group of patients PRP with autogenous bone was used for the sinus lift procedure. In the other group autogenous bone was used alone, under local anesthesia. Patients case records were maintained including detailed case history, IOPA radiograph, opg and photographs. All the procedures were done with a follow up of 6 months to check for graft resorption and bone formation in the grafted area.

The following clinical parameters were noted and analyzed

Pain was assessed by using Visual Analogue Scale^6,7 and Verbal Rating Scale.⁷

Visual Analogue Scale (Score 0-10) 0 -No pain………….10 – Pain cannot be worse

Verbal Rating Scale (VRS) No pain , B- Some pain ,C-Moderate pain, D- Strong pain, E- Very strong pain

Swelling was assessed by its presence or absence

Primary wound healing was assessed by the presence and absence of wound dehiscence on the 7 and 14 day postoperatively.

Extrusion of the graft material

Presence or absence of infection.

Radiographic assessment: Pre and post operative IOPA radiographs and OPG was taken to assess the area of resorption of alveolar bone. OPG were taken after 1 week, 1 month, 2 month & 6 months post-operatively to assess the height of the alveolar bone.

Platelet gel Preparation :

Step 1: Collection of blood- Under aseptic techniques, 40 ml of blood was drawn intravenously from the anticubital region of patient's forearm using vacutainer needle and BD Vacutainers (each 4ml) containing CPDA (0.8ml each).

Step 2: PRP preparation.-The blood was then centrifuged at 2400 rpm for 10mins.The bottom layer is RBCs, the supernatant layer is rest of the whole blood (WBCs, Platelets and Plasma).The two fractions are separated by a thin white line called the buffy coat which has maximum no. of platelets. Plasma and the buffy coat layer is collected in a fresh vacutainer and again centrifuged at 3600 rpm for 15 mins. The second spin results in two separate fragments- The bottom layer is Platelet rich plasma (PRP).

Step 3: PRP gel preparation-PRP is mixed with 0.5 to 1cc of 10% CaCl2 and autologous blood to yield PRP gel. 

Procedure for harvesting tibial bone graft:^8,9

A medial approach to the tibia avoids the insertion of the iliotibial tract & several other anatomic landmarks. The landmarks are 2 lines: one vertical line drawn through the patella & the tibial tuberosity & the other perpendicular to the first, through the tibial tuberosity. An oblique skin incision is made centred over a point 15mm superior to the horizontal line & 15mm medial to the vertical line. Dissection continues through the periosteum overlying the bone underneath the incision. A bone window is made to provide access to the cancellous bone, which is harvested with curettes. No attempt is made to fill the metaphyseal dead space & no drains are used. The wound is closed in layers.

Lateral antrostomy for sinus augmentation:

Posterior maxilla consists mostly of thin cortices & spongy cancellous compartments. A crestal incision with an anterior releasing incision was placed in the posterior edentulous maxilla. Flap was reflected to expose the bone covering the lateral part of the maxillary sinus with a round bur, an antrostomy approximately 10mm in diameter was made in the lateral antral wall. The membrane was dissected and elevated from the entire floor of the maxillary sinus. The bone window was intruded into the sinus like a trapdoor. The space underneath was filled with autogenous bone in 10 cases & autogenous bone with PRP in another 10 cases. The augmentation material was placed underneath the intruded bone window with slight pressure & the remaining spaces were filled with bio-oss sponges 0.25 to 1mm in size. Afterward the lateral aspect was covered with proguide, a resorbable collagen membrane to prevent fibroblasts from growing into the augmented area. Suturing of the flap is then done with 3.0 vicryl. Routine post-operative instructions were given along with antibiotics & analgesics. Patient was asked to be on soft diet for 2 weeks and was advised to use chlorhexidine mouthwash twice daily.

Statistical Methods: Descriptive statistical analysis was carried out. Results on continuous measurements are presented on Mean SD (Min-Max) and results on categorical measurements are presented in Number (%). Significance is assessed at 5 % level of significance. Student t test (two tailed, independent) has been used to find the significance of Alveolar bone height between two groups, Fisher Exact /Chi-square test has been used to find the significance of study characteristics between two groups.

RESULTS

Age distribution of study groups

The age group ranged between 18 to 40 years with a mean age of 32.004.89 for group 1 and 30.904.20 for group 2. Samples are age matched with P = 0.597

Male60%Female40%Group II Gender distribution : sex distribution of study groups. Samples are gender matched with P = 1.000

Evaluation of pain by Visual analogue scale : Evaluation of pain by Visual analogue scale. Pain on the 1stpost-operative day is moderately significant in group I than in group II with a P = 0.030

Evaluation of Pain assessment by Verbal rating scale: The results show no significant difference between the 2 groups with P = 1.000. 50% of the patients complained of some pain and the other 50% complained of moderate pain in group I whereas all the patients complained of some pain in the 2nd group at 1stpost-operative day.

Evaluation of Swelling : The results show no significant difference between the 2 groups with P = 1.000

Evaluation of Wound Dehiscence: The results show no significant difference between the 2 groups with P = 1.000

Evaluation of Extrusion of graft material : The results show no significant difference between the 2 groups with P = 1.000 

Evaluation of Infection : no significant difference between the 2 groups with P = 1.000

Assessment of alveolar bone height (mm) in two groups: The results show alveolar bone height pre operatively in the 2 groups evenly matched with P = 0.556. The results at the end of 1st week showed 8.000.76mm of bone height in group I and 7.630.74mm of bone height in group II with P = 0.334. The height of the alveolar bone at the end of 1st month were evenly matched with P = 0.770. The height of the alveolar bone at the end of 6th month showed values of 10.630.92mm in group I and the height of the alveolar bone in the 2nd group showed values of 12.130.64mm with strongly significant value of P = 0.002.

DISCUSSION

Tooth loss in the posterior maxilla results in rapid resorption of both horizontal and vertical alveolar bone due to lack of intra osseous stimulation by periodontal ligament fibres.

Osseointegrated implants placement in the posterior maxilla frequently poses challenges because of the small height of residual bone, risk of perforation of the sinus membrane that may result in sinusitis, possible implant migration into the maxillary sinus and other complication¹⁰. The autograft contains osteogenic, osteoinductive, osteoconductive properties, a high number of viable cells rich in growth factors. The minimum platelet count concentration of about 1 million platelets/μl, or about 4-7 times the usual baseline 3 platelet count has been shown to provide clinical benefits. Platelet rich plasma is a way to accelerate and enhance the body's natural wound healing mechanisms. In the present study PRP was prepared one hour prior to surgery and when the platelet count was checked, the number of platelets were 4 times greater than the baseline value of 1.5 lakh/ μl. The increased number of platelets stimulates all phases of healing. This method is also preferred because it requires less amount of blood, less time for preparation and can be used in routine dental set up.

The PRP is activated to form PRP gel thus causing degranulation of alpha granules present in the platelets and releasing the growth factors. In our technique CaCl2 and autologous blood was mixed with PRP to form an autologous platelet gel.

PRP when combined with autogenous bone, results in considerably faster radiographic maturation and  histomorphometrically denser bone regeneration^3,9,11. The results of our study has also radiographically shown mean increased bone height with PRP and autogenous bone graft of 4.23 mm as compared to 2.53mm with autogenous bone graft only at the end of 6 months. Our results with regard to enhanced soft tissue healing and increased rate of bone formation may be attributed to the above mentioned advantages that PRP possesses.

The limitation of the present study was that the sample size was small consisting of 20 patients and the 6 month post-operative follow up is a short duration, hence a study with a large sample size with longer follow up time period is required to analyse the results.

CONCLUSION

In conclusion it can be said that PRP considerably influences bone formation when used along with autogenous bone in maxillary sinus augmentation procedures than only when autogenous bone alone is used. This increase in bone height is more appreciable in comparison at the end of six months of sinus augmentation procedures between the two groups. Since this study is done on a smaller sample size, further multicentric randomized controlled studies are required with longer duration of follow up to authenticate this.