Gerardo Gómez Moreno

Biomechanical and bone histomorphological evaluation of two surfaces on tapered and cylindrical root form implants: an experimental study in dogs.

PURPOSE The aim of this study was to evaluate the early bone response of tapered and cylindrical root form implants with two different surface treatments in fresh extraction sockets after 4 and 8 weeks. MATERIALS AND METHODS Surface treatments and implant design comprised (n = 9 each): tapered with dual acid-etched surface; tapered with dual acid-etched and sandblasted surface (T DAE SB); cylindrical with dual acid-etched surface (C DAE); and cylindrical with dual acid-etched and sandblasted surface (C DAE SB). Implants were placed in the distal sockets of mandibular premolars (2 P2, 3 P3, 4 P4 ) of six beagle dogs, remaining in vivo for 4 and 8 weeks. After sacrifice, the implants were subjected to torque to the point of interface fracture and subsequently nondecalcified for histomorphological study. Statistical analysis was performed by a General Linear Model (GLM) analysis of variance model with a significance level of 5%. RESULTS Torque to interface fracture was significantly greater for the C DAE SB group than for the other groups (p < .001). Histomorphological analysis showed woven bone formation around all implant surfaces at 4 weeks and its replacement by lamellar bone at 8 weeks. Study time (4 or 8 weeks) did not affect torque measures. CONCLUSIONS The double acid-etched and sandblasted sample surface increased early bone biomechanical fixation of both cylindrical and tapered root form implants. The cylindrical root form implants showed higher torque to interface fracture values when compared with the tapered root form implants. The C DAE SB surface group showed the highest biomechanical fixation values (p < .001).

Bone remodeling at implants with different configurations and placed immediately at different depth into extraction sockets. Experimental study in dogs

OBJECTIVES This study evaluated the effect of implant macrodesign and position, related to the bone crest, on bone-to-implant contact (BIC) and crestal bone (CB) in immediate implants. MATERIAL AND METHODS The study comprised of six foxhound dogs in which 48 immediate implants were placed. Three types of implants from the same manufacturer with similar surface characteristics but different macrodesigns were randomly placed: Group A (external hex with no collar microthreads), Group B (internal hex and collar microrings), and Group C (internal conical connection and collar microrings). Half of the implants were placed leveled with the bone crest (control) and the remaining, 2 mm subcrestally (test). Block sections were obtained after 12 weeks and processed for mineralized ground sectioning. Statistical analysis consisted of nonparametric Friedman and Wilcoxon test. RESULTS All implants were clinically stable and histologically osseointegrated. Mean BIC percentage within the control group was as follows: A: 42.52 ± 8.67, B: 35.19 ± 18.12, and C: 47.46 ± 11.50. Within the test group: A: 47.33 ± 5.23, B: 48.38 ± 11.63, and C: 54.88 ± 11.73. Differences between each subgroup in the test and the control groups were statistically significant. BIC was statistically significantly higher in the test (50.588 ± 8.663) than in the control (43.317 ± 9.851) group. Within both groups, differences between group C and the other 2 were statistically significant. Distance from the implant shoulder to the buccal CB was statistically significantly larger in the control than in the test group and between subgroups B and C in the control and test groups. Within the test groups, relative bone gain was noticed. CONCLUSIONS Subcrestal immediate implant positioning may lead to a relatively reduced CB resorption and increased BIC. Implants macrodesign with crestal microrings may enhance BIC in post-extraction implants.

Pre‐operative measurement of the volume of bone graft in sinus lifts using CompuDent

OBJECTIVE The aim of this study was to calculate the volume of graft necessary for rehabilitation using varying lengths of implants, and to evaluate the usefulness of the planning dental software in determining the pre-operative volume of bone graft in maxillary sinus floor lifts. MATERIAL AND METHODS Using the CompuDent program, we calculated the volume of graft necessary for 62 sinus lifts. This volume was measured to raise the floor of each sinus to 13.4 and 15 mm in height. RESULTS The average volume of graft to achieve a lift of 13.4 mm was 2.61 ± 0.69 cm³ for the right maxillary sinus, with the range of 1.38-4.1 cm³, and 2.68 ± 0.81 cm³ for the left maxillary sinus, with the range of 1.1-4.25 cm³. The average volume of graft to achieve a lift of 15 mm was 3.13 ± 0.75 cm³ for the right maxillary sinus, with the range of 1.59-4.81 cm³, and 3.29 ± 1.02 cm³ for the left maxillary sinus, with the range of 1.48-5.11 cm³. The statistical results showed a significant inversely proportional correlation between the average of the heights and the volume of graft in the right sinus. CONCLUSIONS The planning dental software is an effective tool in determining the volume of bone graft given the tools simplicity, rapidness and possibility of standardization in all pre-surgical procedures.

Bone healing at implants with different surface configurations: an experimental study in dogs

OBJECTIVE To study osseointegration of implants with surface modifications by the use of fluoroboric acid and/or H2 O2 installed in conventional sites or sites with circumferential marginal defects. MATERIAL AND METHODS Four implants with different surfaces were used. One basic surface (ZirTi(®)) was sandblasted with zirconium microspheres and acid etched additionally with hydrofluoric acid. A second surface was treated with fluoroboric acid instead of hydrofluoric acid. The remainder of the other two surfaces was additionally treated with H2O2. The edentulous mandibles of 6 foxhound dogs were used to randomly install 8.5-mm-long implants with the different surfaces and to study the histological healing after 1 and 3 months. To study osteoconductivity, additional four recipient sites were prepared with the coronal region being widened so that a 4 mm deep and 0.85 mm wide marginal defect resulted after the placement of the four implants with different surfaces. No filler material or membranes were used, and a fully submerged healing was allowed for 3 months. RESULTS At the conventional sites, new bone formation ranged between 68.5% and 74.9% after 1 month. After 3 months, bone-to-implant contact ranged from 72.6% at the ZirTi(®) surface to 84.1% at the fluoroboric acid-treated implants, the difference being statistically significant. At the sites with marginal defects, bone formation ranged from 0.77 mm at the surface treated with fluoroboric acid and H2O2 , to 1.93 mm at the surface treated with fluoroboric acid alone. CONCLUSIONS Fluoroboric acid treatment alone of titanium implant surfaces resulted in improved osseointegration and osteoconductivity after 3 months.