Peri-implant Bone Reactions Research Articles

Evaluation of cervical peri-implant optical density in longitudinal control of immediate implants in the anterior maxilla region.

This research aimed to longitudinally evaluate the optical density of peri-implant alveolar bone. The data acquired from study participants previously treated with 37 osseointegrated implants were analyzed utilizing the radiographic subtraction technique. The radiographic follow-ups were performed five times: at the implantation of the prostheses and after 15, 90, 180 and 360 days. Intraoral radiographs were obtained by the paralleling technique using individualized Hanshin-type positioners to guarantee the standardization of the images. The obtained digital images were aligned and equalized before they were submitted to the radiographic subtraction procedure. A significant difference was found between the distal region of Group I (patients treated with osseointegrated implants who required extraction of the dental element) and the 360 day follow-up and the distal region of Group II (patients with healed alveolar sockets) in all follow-up analyses (p < 0.05). We did not observe a significant difference between the groups analyzed and other follow-ups concerning the subcrestal and middle third regions for both the mesial and distal variables (p > 0.05). There was a statistically significant difference in the distal sites [χ2 = 5,745,, p = 0.03], showing a significant association between time and the presence of bone resorption. This association was not shown on the mesial surface (p = 0.16). We concluded that there was no statistically significant difference between groups I and II. Using this technique, we were able to quantitatively and qualitatively evaluate the changes in the proximal sites on the digital radiographic images for the analyzed data. Digital subtraction technology to measure peri-implant bone density is an accurate and reproducible technique for quantifying peri-implant bone reactions to different therapeutic modalities.

Retraction.

Negri B, Calvo-Guirado JL, Ramírez-Fernández MP, Maté Sánchez-de Val J, Guardia J, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part II: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 236-244. The above article, published online on 5 September 2011 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 23, pp. 236-244, has been retracted by agreement between the journal Editor in Chief, L Heitz-Mayfield, and John Wiley & Sons Ltd. The retraction has been agreed due to image discrepancies, resulting in unreliable data. Images in Figure 8 have been used in another publication representing different time points. Reference Negri B, Calvo-Guirado JL, Ramírez-Fernández MP, Maté Sánchez-de Val J, Guardia J, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part II: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 236-244. https://doi.org/10.1111/j.1600-0501.2011.02290.x.

Retraction

Negri B, Calvo-Guirado JL, Pardo-Zamora G, Ramírez-Fernández MP, Delgado-Ruíz RA, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 228-235. The above article, published online on 24 March 2011 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 23, pp. 228-235, has been retracted by agreement between the journal Editor in Chief, L Heitz-Mayfield, and John Wiley & Sons Ltd. The retraction has been agreed due to image discrepancies, resulting in unreliable data. Images in Figure 6a have been used in another publication representing different time points. Reference Negri B, Calvo-Guirado JL, Pardo-Zamora G, Ramírez-Fernández MP, Delgado-Ruíz RA, Muñoz-Guzón F. Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs. Clin Oral Impl Res. 2012;23: 228-235. https://doi.org/10.1111/j.1600-0501.2011.02158.x.

Impact of Dynamic and Static Load on Bone Around Implants: An Experimental Study in a Rat Model.

This study aimed to evaluate peri-implant bone reactions to dynamic and static loads in a rat model. Two cylindrical titanium implants were placed in the left tibia diaphysis of 39 rats, which were divided into three groups: static load for 4 weeks (S4), static load for 8 weeks (S8), and static load for 4 weeks followed by dynamic load for 4 weeks (S4D4). All implants received a mechanical lateral load. After the experiment, the implants were extracted to determine the attachment strength around the bone and implant. The new bone formation and bone-to-implant contact were measured using plain and polarized light microscopy. Histologic tissue analysis revealed good contact between the bone and implant, and new bone formation around all implants. The S4D4 group had the greatest attachment strength, new bone formation, and complex collagen fiber orientation in the new bone tissue, compared with the other groups. No statistically significant differences in bone-to-implant contact were observed among the three groups. Applying dynamic and static loads to osseointegrated implants increased the amplification of new bone. The attachment strength was significantly improved when dynamic load was used for 4 weeks, compared with when static load was used.

Correlation Between Stress Distributions and Biological Reactions in Bone Surrounding Implants That Support Cantilevers in Supraocclusal Contact in Rats.

To investigate the relationship between stress distributions and peri-implant bone reactions around maxillary implants that support cantilevers in supraocclusal contact. After molar extraction, 16 Wistar rats received a titanium implant unilaterally. After healing, 8 rats (control group) were killed and the others received implant-supported cantilever superstructures in supraocclusion (loaded group). After 5 days, they were killed. The maxillae of all rats were scanned by microcomputed tomography (μ-CT). Based on the μ-CT images, bone volumes were measured. For the loaded group, 3D finite element models were created and analyzed under 20-N vertical and 5-N lateral forces, successively. After μ-CT scanning, sections were prepared and observed histologically. When compared with the controls, the bone volume tended to decrease in the loaded group, but the difference was not statistically significant. On average, marginal bone resorption and stresses tended to be higher in 2 rats that occluded on the cantilever arm than in the others, which occluded right on the implant, nevertheless, calculated stress did not surpass the maximum elastic stress (yielding strength) of rat bone. However, at the implant-bone interface of these samples, partial bone resorption surrounded by signs of active resorption was histologically found. These findings suggest that in this occlusally loaded rat model, the stress distributions correlated to some extent with bone volume and morphological changes observed on μ-CT images and histological sections.

Influence of a Machined Collar on Crestal Bone Changes Around Titanium Implants: A Histometric Study in the Canine Mandible

It has been shown that peri-implant crestal bone reactions are influenced by both a rough-smooth implant border in one-piece, non-submerged, as well as an interface (microgap [MG] between implant/abutment) in two-piece butt-joint, submerged and non-submerged implants being placed at different levels in relation to the crest of the bone. According to standard surgical procedures, the rough-smooth implant border for implants with a smooth collar should be aligned with the crest of the bone exhibiting a smooth collar adjacent to peri-implant soft tissues. No data, however, are available for implants exhibiting a sandblasted, large-grit and acid-etched (SLA) surface all the way to the top of a non-submerged implant. Thus, the purpose of this study is to histometrically examine crestal bone changes around machined versus SLA-surfaced implant collars in a side-by-side comparison. A total of 60 titanium implants (30 machined collars and 30 SLA collars) were randomly placed in edentulous mandibular areas of five foxhounds forming six different subgroups (implant subgroups A to F). The implants in subgroups A to C had a machined collar (control), whereas the implants in subgroups D to F were SLA-treated all the way to the top (MG level; test). Furthermore, the MGs of the implants were placed at different levels in relation to the crest of the bone: the implants in subgroups A and E were 2 mm above the crest, in subgroups C and D 1 mm above, in subgroup B 3 mm above, and in subgroup F at the bone crest level. For all implants, abutment healing screws were connected the day of surgery. These caps were loosened and immediately retightened monthly. At 6 months, animals were sacrificed and non-decalcified histology was analyzed by evaluating peri-implant crestal bone levels. For implants in subgroup A, the estimated mean crestal bone loss (± SD) was -0.52 ± 0.40 mm; in subgroup B, +0.16 ± 0.40 mm (bone gain); in subgroup C, -1.28 ± 0.21 mm; in subgroup D, -0.43 ± 0.43 mm; in subgroup E, -0.03 ± 0.48 mm; and in subgroup F, -1.11 ± 0.27 mm. Mean bone loss for subgroup A was significantly greater than for subgroup E (P = 0.034) and bone loss for subgroup C was significantly greater than for subgroup D (P <0.001). Choosing a completely SLA-surfaced non-submerged implant can reduce the amount of peri-implant crestal bone loss and reduce the distance from the MG to the first bone-implant contact around unloaded implants compared to implants with a machined collar. Furthermore, a slightly exposed SLA surface during implant placement does not seem to compromise the overall hard and soft tissue integration and, in some cases, results in coronal bone formation in this canine model.

Peri-implant bone reactions around immediately loaded conical implants with different prosthetic suprastructures: histological and histomorphometrical study on minipigs

The aim of this study was to evaluate peri-implant bone reactions around immediately loaded conical implants with metal and acrylic resin prosthetic restorations. Five splinted conical implants were inserted in each hemimandible of six minipigs at the alveolar crest level. Ten implants were inserted in each minipig. All the implants were immediately loaded. The implants were divided into a group with an acrylic resin prosthetic restoration and into another group with a metal prosthetic restoration. No postoperative complications or deaths of the minipigs occurred. All minipigs were killed after 3 months. No implant was lost. A total of 60 implants were retrieved and processed to obtain thin ground sections. Histology and histomorphometry showed the presence of compact, mature bone around all the implants. Bone was in close contact with the implant surface starting from the first or second implant threads. A high quantity of mineralized bone was present around immediately loaded conical, root form implants. No differences in the peri-implant bone response were found in the groups with different prosthetic reconstructions.

Peri-implant bone reactions at delayed and immediately loaded implants: an experimental study

The aim of this study was to compare the peri-implant bone reactions of implants subjected to immediate loading with those subjected to delayed loading. In 6 mongrel dogs, bilateral edentulated flat alveolar ridges were created in the mandible. After 3 months of healing, 1 implant was placed in each side. On one side of the mandible, the implant was loaded immediately with a force of 20 N that was applied at a 120 degrees angle from the tooth's longitudinal axis at the labial surface of the crown for 1800 cycles per day for 10 weeks. On the opposite side, after a delay of 3 months to allow osseointegration to take place, the implant was loaded with the same force used for the immediately loaded implant. Ten weeks after loading, microscopic computerized tomography at the implantation site was performed. Osseointegration was calculated as the percentage of implant surface in contact with bone. Bone height was measured in the peri-implant bone. The mean osseointegration was greater (65.5%) for the delayed-loading implants than for the immediately loaded implants (60.9%; P < .05). The mean peri-implant bone height was greater (10.6 mm) for the delayed-loading implants than for the immediately loaded implants (9.6 mm; P < .05). The results indicate that when implants are immediately loaded, the immediate loading may decrease both osseointegration of dental implants and bone height.