Dental implants: early versus standard two-stage loading (animal study)

Direct bone formation on the implant surface is a treatment goal in implant dentistry. It was always thought that a healing period of 3 months for the lower jaw and 5-6 months for the upper jaw was required for osseointegration to occur. Recent studies, however, show that with the early loading protocol, osseointegration is possible as well. The goal of this study was to evaluate clinical, histologic, and histomorphometric parameters of implants with early loading protocols and implants that did not undergo the early loading protocol. In this experimental study, the first to the fourth premolar teeth were extracted from the lower jaws of 3 dogs. After a healing period of 3 months, 12 BioHorizons internal implants 4.5 × 10.5 mm were placed in the mandible of the dogs. The implant stability quotient (ISQ) was recorded. After 3 weeks, half of the implants were exposed, and after recording ISQ, polycarbonate crowns were placed on them and occlusion was adjusted so that there was no contact in centric occlusion and no lateral movement with the opposing teeth. After 3 months, the ISQs were recorded for all the implants. Bleeding upon probing and pocket depths were measured for the early loading implants. All the implants were removed using a trephine bur, and cross-sections of 150 μm were prepared, from which the bone implant contact (BIC) and the type of bone around them were obtained. Statistical analysis was conducted with independent t test, paired t test, and repeated analysis of variance. The BIC for the early loaded group was 46.17% ± 12.89%, and for the unloaded group was 44.4% ± 10.45%. This difference was not statistically significant (P = .811). The ISQ for the implants in the early loaded group (before they were removed) was 71 ± 7.35 and that of the unloaded group was 66.75 ± 11.86 .These differences were statistically insignificant. With regard to the result of this study, and the fact that the 2 groups showed no statistically significant differences in a number of major aspects, such as BIC and ISQ, it seems possible to load implants with an earlier than usual protocol with no adverse effects on implant success. It is necessary, however, to follow certain protocols for this type of loading.