Libros

The aim of this study was to evaluate the effectiveness of hyaluronic acid (HA) injections used to reduce defects in the gingival papillae in esthetic areas. This randomized study included six patients requiring black triangle treatment in 19 defective papillae. After local anesthesia, less than 0.2 mL of HA was injected 2 to 3 mm into the tip of the deficient papilla in the apical direction. Analysis of the target regions with standardized photographs and 3D intraoral scanning (CEREC 4.5 software with RST files, Dentsply Sirona) was performed at baseline (T0) and at 1 month (T1), 2 months (T2), 3 months (T3), and 4 months (T4) after the initial application of HA. At each time period, the photographic analysis showed no statistically significant differences in linear tissue gain after HA gel application. The 3D analysis showed improvements in the vertical papillae tissue recovery at T3 (0.41 ± 0.21 mm) and T4 (0.38 ± 0.21 mm) when compared to T1 (0.13 ± 0.08 mm; P < .0001). Regarding the reconstruction of the interdental papillae, the general dimensions of the tissue in the black triangle areas showed a significant increase in size percentage at T3 (58% ± 32.9%) compared to T1 (30.41% ± 23.4%; P = .0054). Thus, the application of injectable HA was effective for filling papillae in the esthetic area.

Purpose: This study evaluated and compared bone heating, drill deformation, and drill roughness after several implant osteotomies in the guided surgery technique and the classic drilling procedure. Materials and Methods: The tibias of 20 rabbits were used. The animals were divided into a guided surgery group (GG) and a control group (CG); subgroups were then designated (G0, G1, G2, G3, and G4, corresponding to drills used 0, 10, 20, 30 and 40 times, respectively). Each animal received 10 sequential osteotomies (5 in each tibia) with each technique. Thermal changes were quantified, drill roughness was measured, and the drills were subjected to scanning electron microscopy. Results: Bone temperature generated by drilling was significantly higher in the GG than in the CG. Drill deformation in the GG and CG increased with drill use, and in the CG a significant difference between G0 and groups G3 and G4 was observed. In the GG, a significant difference between G0 and all other groups was found. For GG versus CG, a significant difference was found in the 40th osteotomy. Drill roughness in both groups was progressive in accordance with increased use, but there was no statistically significant difference between subgroups or between GG and CG overall. Conclusion: During preparation of implant osteotomies, the guided surgery technique generated a higher bone temperature and deformed drills more than the classic drilling procedure. The increase in tissue temperature was directly proportional to the number of times drills were used, but neither technique generated critical necrosisinducing temperatures. Drill deformation was directly proportional to the number of times the drills were used. The roughness of the drills was directly proportional to the number of reuses in both groups but tended to be higher in the GG group. Palabras clave: bone overheating, dental implants, osteotomy

The purpose of this study was nondecalcified histologic analysis of titanium implants modified by laser with and without hydroxyapatite. Implants with three modified surfaces were inserted into rabbit tibias: group 1, machined surface; group 2, irradiated (laser); and group 3, irradiated and hydroxyapatite coated (biomimetic method). The mean surface roughness (Ra) scores of groups 2 and 3 were higher than that of group 1. Boneimplant contact measurements at 30 and 60 days for groups 2 and 3 were higher than for group 1. Bone area at 30 and 60 days for group 2 was higher than for groups 1 and 3. Titanium implants modified by laser with and without hydroxyapatite exhibit increased early osseointegration.

Purpose: The purpose of this study was to evaluate the influence of reusing high-resistance drills on bone heating, immediate bone cell viability, and drill wear after performing implant osteotomies in rabbit tibias. Materials and Methods: Two hundred sequential implant osteotomies were created in the superior tibial cortex of 12 White male rabbits. Six groups were established (G1 to G6) according to the number of osteotomies performed with each drill (0, 10, 20, 30, 40, and 50). Drilling began with a spear drill, followed by 2.0-mm, 2.8-mm, 3.0-mm, and 3.15-mm helical drills. The receptor beds were collected for immunohistochemical analysis, thermal changes were quantified, and the drills were subjected to scanning electron microscopy analysis. Results: A high degree of correlation between drill wear and number of osteotomies was observed (Pearson correlation coefficient, r = 0.984). Spear drills underwent twice as much deformation as helical drills. The bone heating analysis concluded that there was no statistically significant relationship between the number of osteotomies and bone heating (P > .05), but there were greater thermal changes during drilling with the spear drill than during drilling with helical drills (ratio 3:1). Immunohistochemical analysis showed a physiologic balance of osteoprotegerin and RANKL (receptor activator of nuclear factor κB ligand) immunolabeling in all groups; however, there was greater immunolabeling of all proteins in group G6 (50 osteotomies). Conclusions: The tested drills did not cause significant bone heating after being reused 50 times; however, they caused more tissue trauma in the 50th osteotomy. Worn drills that are reused may be expected to cause excessive damage to the bone tissue and could adversely affect the osseointegration process. Palabras clave: cell survival, dental implants, immunohistochemistry, osteotomy, scanning electron microscopy

Purpose: This study was proposed to analyze histologically the process of repairing bone defects created surgically in the cranial vaults of rabbits. Materials and Methods: Thirty adult male rabbits (Oryctolagus cunilicus) received, under general anesthesia, bilateral parietal osteotomies by means of a 6-mm-diameter trephine. The bony defects were divided into 4 groups. In group 1 the defect did not receive any treatment; in group 2 the defect was filled with lyophilized bovine bone (Biograft); in group 3 it was filled with bovine bone and covered with a bone matrix membrane (Bioplate); in group 4 it was covered with a bone matrix membrane. Animals were sacrificed in 3 equal groups at 15, 30, and 60 days. The specimens were subjected to routine laboratory procedures to evaluate the degree of bone repair. Results: After 60 days, new bone formation in group 2 was not satisfactory when compared to that of group 3. Large amounts of new bone formation in maturation were seen in group 3. In the defects covered with a membrane the results were similar to those of group 1 (ie, the cavity was filled with fibrous connective tissue). The implanted bone and membranes were totally resorbed. Discussion and Conclusions: The use of a membrane served as a barrier against the migration of cells from the adjacent tissue and the bone graft/membrane preserved the cavity space, resulting in an enhanced osteogenic effect. Palabras clave: bone grafting, bone regeneration, cranial vault reconstruction, resorbable membranes, xenografts