Influence of Interimplant Distance on Bone Microstructure: A Histomorphometric Study in Dogs

Abstract

The microstructure of the crestal alveolar bone is important for both the maintenance of osseointegration and the location of the gingival soft tissues. The aim of this study was to evaluate and compare the bone microstructure of the alveolar bone and of the interimplant bone in implants inserted at different interimplant distances. The mandibular bilateral premolars of six dogs were extracted, and after 12 weeks, each dog received eight implants, for a total of 48 implants. Two pairs of implants, one for each hemiarch, were separated by 2 mm (group 1) and by 3 mm (group 2). After 12 weeks, the implants received temporary acrylic prostheses. After four more weeks, metallic crowns substituted the temporary prostheses. After an additional 8 weeks the animals were sacrificed and the hemimandibles were removed, dissected, and processed. The longitudinal collagen fiber orientation was 43.2% for the alveolar bone; it was 30.3% for the 2-mm group and 43.9% for the 3-mm group. There was a statistically significant difference between the 2-mm and 3-mm groups (p < .05). The orientation of transverse collagen fibers was 47.8% for the alveolar bone; it was 37.3% for the 2-mm group and 56.3% for the 3-mm group. There was a statistically significant difference between the 2-mm and 3-mm groups (p < .05). The marrow spaces were 34.87% for the alveolar bone, 52.3% for the 2-mm group, and 59.9% for the 3-mm group. There was a statistically significant difference between the alveolar bone and the 3-mm group (p < .05). The low mineral density index was 36.29 for the alveolar bone, 46.76 for the 2-mm group, and 17.91 for the 3-mm group. There was a statistically significant difference between the 2-mm and 3-mm groups (p < .05). The high mineral density was 87.57 for the alveolar bone, 72.58 for the 2-mm group, and 84.91 for the 3-mm group. There was a statistically significant difference between the alveolar bone and the 2-mm group (p < .05). The collagen fiber orientation resulted in statistically significant differences in both the 2-mm and 3-mm groups compared with the alveolar bone. The marrow spaces appeared significantly increased in the 3-mm group compared with the alveolar bone. The low mineral density index was significantly higher in the 2-mm group, while the high mineral density index was significantly higher in the alveolar bone. In conclusion, the interimplant distance should not be less than 3 mm.

The relationship between interimplant distances and vascularization of the interimplant bone

“… Summary of the data. PH Rx is the papillae height measured radiographically in Novaes et al (2006b)– BL Rx is the crestal bone loss measured radiographically in Novaes et al (2006b)– BL Histo is the crestal bone loss measured histologically in Papalexiou et al (2006)– BD Histo is the bone density measured histologically in Papalexiou et al (2006)– BC long , BC trans , BMS and BMD are the bone collagen longitudinally oriented fibers, the bone collagen transversally oriented fibers, the bone marrow spaces and the mean of bone mineral density respectively, in Traini et al (2008)– BVVD is the bone vessels volume density. ( * ) for the definition of the mineral density index (MDI) we refer to Traini et al (2008).…”

“…Previous studies have shown that interimplant distance can have different effects on the biology and microstructure of the implant surrounding tissues (Novaes et al 2006a, 2006b, 2009a, 2009b; Papalexiou et al 2006; Oliveira et al 2006; Traini et al 2008).…”

Effect of Nanoscale Topography of Titanium Implants on Bone Vessel Network, Osteocytes, and Mineral Densities

“…As recently reported, the current paradigm of bone mechanical adaptation considers the bone cells as smart micromachines able not only to adapt themselves to the spatiotemporally dynamic habitat, but also to modulate the mechanical milieu through production (adaptation) of extracellular matrix (ECM) 6 . Bone adaptation also involves the peri‐implant surrounding bone, as is well documented by several studies 7‐10 …”

Advances in Dental Implant Positioning Techniques and Their Clinical Implications

“…Surrounded by bone of uniform volume and density, with a minimum bone thickness of >1 mm around the implant body to provide good support against multidirectional long-term loading [18] Placed in the geometric centre of the crown to reduce off-axis loading [19] a minimum distance of 1 -1.5 mm between the implant surface and adjacent teeth or 3 mm in the case of an adjacent natural tooth to minimize the potential for damage to the supporting structures [20] a minimum interimplant distance of 3 mm to prevent bone resorption between adjacent implants [21] a 2 mm distance as a safety zone between the implant and the nerve to avoid nerve injury during mandibular implant surgery. In the case of placing any implant anterior to the mental foramen that is deeper than the safety zone, the mental foramen must be explored for an anterior loop [22] bone grafting, and other procedures, presurgical CT examinations should routinely be performed to avoid the risk of surgical complications during implant placement [23] CT should be used to verify the presence of the mandibular lingual vascular canal to evaluate the lingual cortical bone thickness and density, to avoid perforations and life-threatening bleeding [24] Multiple implants should be placed in parallel, to avoid unfavourable off-axis loading [25] Not only just the implant placement but also their distribution is studied in details by various experts.…”