Evaluation of the Effect of Bone Morphogenetic Protein-2 on Stability of Dental Implant

ABSTRACT Background: The healing period for bone–implant contact takes 3–6 months or even longer. Application of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) to implant surfaces has been of great interest on osseointegration due to its osteoinductive potential. The objective of this study was to evaluate the effect of ErhBMP-2 on implant stability. Materials and methods: A total of 48 dental implants were inserted in 15 patients. Twenty four implants coated with 0.5 mg/ml ErhBMP-2 (study group). The other 24 implants were uncoated (control group). Each patient was received at least two dental implants at the same session. Both groups were followed with repeated implant stability measurements by means of resonance frequency analysis at different time intervals (at the time of surgery, then at 6th and 12th week postoperatively). Results: there was no obvious statistically significant difference in mean of implant stability quotient ISQ between study and control groups (P > 0.05) at time of surgery, whereas the mean of ISQ values at 6th and at 12th week postoperatively were statistically highly significant in the study group compared to the control group (p < 0.01). Conclusion: The results of this study reveal that coating dental implants with ErhBMP-2 increases stability when compared with uncoated implants.


INTRODUCTION
Dental implants and other supportive prostheses are commonly used in dentistry, which rely on a variety of factors to ensure function and survival within the host.The search for a most favorable implant feature is one of the major focuses in the research field to accelerate and improve osseointegration (1) .
Multiple design alterations have been attempted, primarily surface modifications, as the implant surface is the first part of the implant that interacts with the bone.Numerous alterations of specific surface features such as structure and chemistry have been successful in speeding up osseointegration at early implantation times which may decrease the total treatment period (1)(2)(3) .
Recently, further modifications to bioactivate the implant surface using a number of growth factors have also been recommended to induce a deposition of cells with the ability of regenerating the desired tissue (4,5) .An increased proliferation and differentiation of undifferentiated mesenchymal cells, osteoprogenitor cells, and preosteoblasts into osteoblasts may improve bone response and consequently osseointegration of endosseous titanium implants (6) .One particular growth factor; bone morphogenetic protein (BMP), governs the 3 key steps in the osteogenic cascade: chemotaxis, mitosis, and differentiation (7) .Bone morphogenetic proteins (BMPs) have shown significant potential to induce bone formation both in ectopic sites (8) , and in defect models in different species (9) .A well known osteoinductive factor, the bone morphogenetic protein-2 (BMP-2) appears to possess the highest osteoinductive potential among the BMPs and has been demonstrated to further stimulate local bone formation and osseointegration (10) .
Huh et al. showed that the ErhBMP-2 coated anodized implants can stimulate bone formation and increase implant stability significantly on completely healed alveolar ridges in dogs (17) .The aim of this study was to evaluate the effect of (ErhBMP-2) coated endosseous dental implants on implant stability.

Subjects:
Fifteen patients 9 women and 6 men, ranged from 33-65 years old were selected for this study.The patients were referred to the dental implant clinic in the Department of Oral and Maxillofacial Surgery/ College of Dentistry Hospital/University of Bagdad.The number of dental implants received at least two dental implants session in the same edentulous region or in a bilaterally symmetric to the median line (split mouth design), one implant was coated with ErhBMP other implant was serve as a control during the period from November

Inclusion criteria
Patient's hygiene.at least 6 months after extraction bone width which not allowed for dehiscence control groups implant design.evaluated by

Exclusion criteria
Heavy smokers (more than 20 ciga day), alcoholism pregnancy, patient with a excluded from this study

Implant systems:
A total of (Implantium surface modified by TiO and acid etching surface were utilized in the study.The diameter of Ø3.4 mm, Ø3.8 mm mm or Ø4.8 mm and a length of 8 mm, 10 mm, 12 mm or 14 jaws, who are selected in the study.

Escherichia coli derived recombinant human bone morphogenetic protein
One vial of rhBMP England) was used in this study.characteristic are described in table (

Ossetell
The implant stability Ossetell.Sweden) SmartPeg Mount then hold the instrument probe close to the top of the SmartPeg® without touching it.An audible sound will be emitted when the instrument senses the SmartPeg® and an ISQ value is generated and shown on the d h College Dentistry

Oral and Maxillofacial Surgery and Periodontics
Surgery/ College of Dentistry /University of Bagdad.The number of dental implants were received at least two dental implants session in the same edentulous region or in a bilaterally symmetric to the median line (split mouth design), one implant was coated with ErhBMP-2, to serve as other implant was uncoated serve as a control group during the period from November 2015.

Inclusion criteria
Patient's are aged Patients have least 6 months after extraction bone width which not allowed for dehiscence and/or fenestration.control groups were provided with implant design.The quality of the bone was evaluated by orthopantomograph

Exclusion criteria
Heavy smokers (more than 20 ciga day), alcoholism, medically c pregnancy, patient with a excluded from this study

Implant systems:
A total of 48 screw (Implantium ® / Dentium surface modified by TiO and acid etching surface were utilized in the study.The diameter of Ø3.4 mm, Ø3.8 mm mm or Ø4.8 mm and a length of 8 mm, 10 mm, 12 mm or 14 mm were placed in jaws, who are selected in the study.

Escherichia coli derived recombinant human one morphogenetic protein
One vial of rhBMP England) was used in this study.characteristic features are described in table ( The implant stability .The SmartPeg® of Ossetell® Sweden) was screwed to the implant by using SmartPeg Mount then hold the instrument probe close to the top of the SmartPeg® without touching it.An audible sound will be emitted when the instrument senses the SmartPeg® and an ISQ value is generated and shown on the d features of BMP used in this study are described in table (1).
The implant stability was he SmartPeg® of Ossetell® screwed to the implant by using SmartPeg Mount then hold the instrument probe close to the top of the SmartPeg® without touching it.An audible sound will be emitted when the instrument senses the SmartPeg® and an ISQ value is generated and shown on the d

Oral and Maxillofacial Surgery and Periodontics
Surgery/ College of Dentistry Teaching /University of Bagdad.The number of 48 fixtures; each patient received at least two dental implants at the same session in the same edentulous region or in a bilaterally symmetric to the median line (split mouth design), one implant was coated with study group, and the with ErhBMP-2, to .The study was conducted October 2014 to ≥ 18 years with good oral ealed edentulous area for least 6 months after extraction with suitable bone width which not allowed for possibility of Both study and were provided with the same The quality of the bone was (OPG).
Heavy smokers (more than 20 cigarettes per ompromised patient, ny local pathosis were titanium implants / Seoul / Korea), with a large grit, sandblasting and acid etching surface were utilized in the study.The diameter of Ø3.4 mm, Ø3.8 mm, Ø4.3 mm or Ø4.8 mm and a length of 8 mm, 10 mm, mm were placed in the Patient's jaws, who are selected in the study.

Escherichia coli derived recombinant human
2 (BMP-2): 2 (0.5 mg /mL; abcam, England) was used in this study.The of BMP used in this study measured he SmartPeg® of Ossetell® (Goteborg, screwed to the implant by using SmartPeg Mount then hold the instrument probe close to the top of the SmartPeg® without touching it.An audible sound will be emitted when the instrument senses the SmartPeg® and an ISQ value is generated and shown on the display.

Implant surgery
Just right before the surgery, the patient rinsed his mouth with Chlorhexidine mouthwash for 1 minute.Then local anesthesia was given using infiltration technique for the design on the labial raised.The implant site was prepared by using high torque handpiece at low speed 800 rpm, with sharp drills, intermittent movement and copious external irrigation to prevent injury to the recipient bone.
For study group with micropipette, some of it dropped on surface of titanium fixture and the remaining amount of ErhBMP-2 inserted into the bony hole before insertion of fixture as shown in figures 3).For control group; implant fixture uncoated with ErhBMP-2

Implant surgery stage I (implant placement):
Just right before the surgery, the patient rinsed his mouth with Chlorhexidine mouthwash for 1 minute.Then local anesthesia was given using infiltration technique for the labial aspect on the implant site was implant site was prepared by using high torque handpiece at low speed 800 rpm, with sharp drills, intermittent movement and copious external irrigation to prevent injury to the recipient bone.
study group; 10 µg with micropipette, some of it dropped on surface of titanium fixture and the remaining amount of inserted into the bony hole before insertion of fixture as shown in figures For control group; implant fixture uncoated 2.

I (implant placement):
Just right before the surgery, the patient rinsed his mouth with Chlorhexidine mouthwash for 1 minute.Then local anesthesia was given using infiltration technique for the planned area.
on the implant site was implant site was prepared by using high torque handpiece at low speed 800 rpm, with sharp drills, intermittent movement and copious external irrigation to prevent excessive injury to the recipient bone.
of ErhBMP with micropipette, some of it dropped on surface of titanium fixture and the remaining amount of inserted into the bony hole before insertion of fixture as shown in figures For control group; implant fixture uncoated

I (implant placement):
Just right before the surgery, the patient rinsed his mouth with Chlorhexidine mouthwash for 1 minute.Then local anesthesia was given using area.A flap on the implant site was implant site was prepared by using high torque handpiece at low speed 800 rpm, with sharp drills, intermittent movement and copious excessive thermal ErhBMP-2 carried with micropipette, some of it dropped on surface of titanium fixture and the remaining amount of inserted into the bony hole before insertion of fixture as shown in figures (     After placement of the the implant stability measurement started ing the SmartPeg® of Ossetell® to the implants of study and control groups readings of the implant stability quotient values were recorded; in a bucco distal directions (4).

Implant surgery stage
After 6 weeks of implant placement, operative OPG was taken to all patients 5).Under local anesthesia, implant procedure is from Dentium (Dentium, Korea) at 35 rpm cover screw was exposed and removed with screw and implants secondary stability were measured in the same manner measurement for both groups size of implant and the thickness of the overlying The cover screw was exposed and removed with screw and implants secondary stability were of primary stability Depending on the size of implant and the thickness of the overlying gingiva, the proper healing abutment (gingival former) was selected and screwed in place the gingival former was removed stability primary stability measurement (2 nd abutments were placed on the implant and take impression to fabricate final prosthesis implants placement gingiva, the proper healing abutment (gingival former) was selected and screwed in place the gingival former was removed stability was measured in the same manner of primary stability measurement nd readings) (figure 6 and 7) abutments were placed on the implant and take impression and send to prosthodontic laboratory to fabricate final prosthesis  Evaluation of the dimension of the titanium healing abutment (gingival former) was selected At 12 th week after surgery, the gingival former was removed and implants measured in the same manner of primary stability measurement for both groups readings) (figure 6 and 7).Then the abutments were placed on the implant and take and send to prosthodontic laboratory as shown in figure (

Evaluation of the
of the titanium healing abutment (gingival former) was selected week after surgery, and implants measured in the same manner of for both groups .Then the abutments were placed on the implant and take and send to prosthodontic laboratory in figure (8).

Statistical analyses
Data were translated into a computerized database structure.Statistical analyses were done using SPSS version 21 computer software.Because we had two ISQ measurements for each implant at each time point (mesio-distal and bucco-lingual measurement), average of the two ISQ measurements was used in this results.The independent samples t-test was used to test the statistical significance of difference in mean between the two groups.A significant difference was considered to exist if the p-value was < 0.05.

RESULTS
The effect of healing period on implant stability quotient (ISQ) in control group: The mean of ISQ reduced by 2.35 units at the 6 th week (2 nd readings) compared to the primary stability value (1 st readings).This mean reduction was statistically non significant.At the 12 th week (3 rd readings), the mean of ISQ increased by an average of 3.06 units compared to the 6 th week, this positive effect was statistically significant.
The change in mean of ISQ after 12 weeks of healing compared to the primary stability value was an average increasing of 0.71 ISQ units, this mean the change was statistically non significant (table 2).The effect of healing period on implant stability quotient (ISQ) in study group: Six weeks after implantation (2 nd readings), the mean of ISQ increased by an average of 8.54 units compared to the primary stability readings (1 st readings), this positive effect was statistically highly significant (p<0.01).
Twelve weeks postoperatively (3 rd readings), the mean of ISQ increased from that of the 6 th week by an average of 2.52 units, also this positive effect was statistically highly significant (p<0.01).The total change in mean ISQ after 12 weeks of implantation compared to the primary stability was increase 11.06 units, which is statistically highly significant (P value < 0.01) (table 3).

Resonance frequency analysis difference between the study and control groups:
As shown in table (4), There was no obvious or statistically significant difference in mean of ISQ between the two groups at time of surgery (P = 0.549), the mean values of ISQ at time of surgery was 66.15 for the control group and 67.27 for the study group.
At 6 th week postoperatively, the difference in mean ISQ was greater in the study group by 12.02 units compared to the control group, this intervention effect was highly significant and evaluated as a strong effect (p<0.01).The difference in mean of ISQ units after 12 weeks of surgery was also highly significant between the study group when compared to the control group and the treatment effect was evaluated as a strong effect (p<0.01,) (figure 9).

DISCUSSION
The ISQ values for the study group were consistently greater than the implants at all time points statistically non significant placement, but the values were statistically highly significant after 6 and 12 weeks placement.This may be due to the use of ErhBMP decrease the period for bone osseointegration and increase secondary stability (biological fixation).agreement with difference in ISQ value was obs control group from the time of surgery to 8 weeks after surgery, whereas the experimental groups (implants dip 1.5 mg/ml) value compared with control group The results were also in agreement with al who found that the ISQ values were significantly higher in the implants immersed in a protein solution (BMP group) than in the control group at 8 weeks after implant placement completely 0.05) (17) .
Similar outcomes were reported in humans after implantation of BMP in extraction sockets with titanium microscrews.Despite the small number of samples in the group, the BMP was related to larger amounts of viable lamellar bone and woven bone compared with the other treatments The results disagree with Salata et al who found that there were no statistically significant differences between

DISCUSSION
The ISQ values for the study group were consistently greater than the implants at all time points statistically non significant placement, but the values were statistically highly significant after 6 and 12 weeks placement.This may be due to the use of rhBMP-2 on surface of dental implant which may decrease the period for bone osseointegration and increase secondary stability (biological fixation).agreement with Huh et al difference in ISQ value was obs control group from the time of surgery to 8 weeks after surgery, whereas the experimental groups (implants dip-coated by ErhBMP mg/ml) showed a significant increase in ISQ value compared with control group results were also in agreement with who found that the ISQ values were significantly higher in the implants immersed in a protein solution (BMP group) than in the control group at 8 weeks after implant placement completely healed alveolar ridg .Similar outcomes were reported in humans after implantation of BMP in extraction sockets with titanium microscrews.Despite the small number of samples in the group, the BMP was related to larger amounts of viable lamellar bone and woven bone compared with the other treatments (20) .
The results disagree with Salata et al who found that there were no statistically significant differences between resonance frequency analysis The ISQ values for the study group were consistently greater than the implants at all time points.T he values wer statistically non significant at time of implant placement, but the values were statistically highly significant after 6 and 12 weeks following placement.This may be due to the use of 2 on surface of dental implant which may decrease the period for bone osseointegration and increase secondary stability (biological fixation).The results were in Huh et al who found that a small difference in ISQ value was obs control group from the time of surgery to 8 weeks after surgery, whereas the experimental groups coated by ErhBMP showed a significant increase in ISQ value compared with control group results were also in agreement with who found that the ISQ values were significantly higher in the implants immersed in a protein solution (BMP group) than in the control group at 8 weeks after implant placement healed alveolar ridges in dogs Similar outcomes were reported in humans after implantation of BMP in extraction sockets with titanium microscrews.Despite the small number of samples in the group, the BMP was related to larger amounts of viable lamellar bone and woven bone compared with the other The results disagree with Salata et al who found that there were no statistically significant resonance frequency analysis

( 1 )
Master student.Department of Oral and Maxillofacial Surgery.College of Dentistry, University of Baghdad.(2) Assistant professor.Department of Oral and Maxillofacial Surgery.College of Dentistry, University of Baghdad.
Teaching /University of Bagdad.The number of 48 fixtures; each patient he same session in the same edentulous region or in a bilaterally symmetric to the median line (splitmouth design), one implant was coated with study group, and the , surface were utilized in the Ø4.3 mm or Ø4.8 mm and a length of 8 mm, 10 mm, Patient's Escherichia coli derived recombinant human 2 (0.5 mg /mL; abcam, The of BMP used in this study d by (Goteborg, screwed to the implant by using SmartPeg Mount then hold the instrument probe close to the top of the SmartPeg® without touching it.An audible sound will be emitted when the instrument senses the SmartPeg® and an isplay.

Figure 9 :
Figure 9: Resonance frequency analysis values of the study and control groups.

:
Resonance frequency analysis values of the study and control groups.