PURPOSE

The study was designed to investigate the effect of surface chemical modification on the process of bone defect healing around implants in dogs.

METHODS

Six Beagle dogs were used in this study. The mandibular premolars and first molars were extracted bilaterally. Three months after tooth extraction the procedure of implant placement was performed. Four canals with a diameter of 2.8 mm and 10 mm in depth were prepared at the third premolar (P3) and the first molar (M1) sites of both sides of the mandible, of which the coronal 5 mm portion were further widened with the 5.3 mm diameter twist drill. In each side of the mandible one modSLA (chemically-modified SLA) implant and one SLA (sandblasted, large-grit, acid-etched) implant with a diameter of 3.3 mm and 10 mm in length were installed, respectively. Thus, the circumferential defect that was 5mm deep and 1mm wide created between the implant surface and the bony wall. Four implants placed in both sides of the mandible were allowed for non-submerged healing. Two dogs were sacrificed at the week 2, 4 and 8 following implant placement, respectively, and the specimens were prepared and stained with trinitrophenol- fuchsin for histological and histomorphometric analyses to acquire the bone-to-implant contact (BIC%), new bone fill (NBF%) and the distance between the most coronal level of bone-to-implant contact and the bottom of the surgically created bone defect(B-D). Statistical analysis was conducted with SPSS13.0 software package.

RESULTS

No implant was loosen or lost during the study. The histomorphometric results demonstrated that new bone formation was observed in the defect region around both groups of implants at all time points and the newly formed bone occurred initially from the apical and lateral bony wall of the defect region, the bone defect almost was filled at week 8. At 2 and 4 weeks of healing, the BIC%, NBF% and B-D values were significantly higher for modSLA implants (P<0.05). At 8 weeks of healing, the difference was not significant (P>0.05).

CONCLUSIONS

The SLA implants processed by means of chemically-modified surface treatments exhibit more predictable outcomes than that of SLA implants by promoting the early bone regeneration when inserted into sites with bone defects.