Impact of simultaneous placement of implant and block bone graft substitute: an in vivo peri-implant defect model.

BACKGROUND: Insufficient bone volume around an implant is a common obstacle when dental implant treatment is considered. Limited vertical or horizontal bone dimensions may lead to exposed implant threads following placement or a gap between the bone and implant. This is often addressed by bone augmentation procedures prior to or at the time of implant placement. This study evaluated bone healing when a synthetic TiO2 block scaffold was placed in circumferential peri-implant defects with buccal fenestrations. METHODS: The mandibular premolars were extracted and the alveolar bone left to heal for 4 weeks prior to implant placement in six minipigs. Two cylindrical defects were created in each hemi-mandible and were subsequent to implant placement allocated to treatment with either TiO2 scaffold or sham in a split mouth design. After 12 weeks of healing time, the samples were harvested. Microcomputed tomography (MicroCT) was used to investigate defect fill and integrity of the block scaffold. Distances from implant to bone in vertical and horizontal directions, percentage of bone to implant contact and defect fill were analysed by histology. RESULTS: MicroCT analysis demonstrated no differences between the groups for defect fill. Three of twelve scaffolds were partly fractured. At the buccal sites, histomorphometric analysis demonstrated higher bone fraction, higher percentage bone to implant contact and shorter distance from implant top to bone 0.5 mm lateral to implant surface in sham group as compared to the TiO2 group. CONCLUSIONS: This study demonstrated less bone formation with the use of TiO2 scaffold block in combination with implant placement in cylindrical defects with buccal bone fenestrations, as compared to sham sites.

Coating doxycycline on titanium-based implants: Two in vivo studies.

Regardless of the substantial progress in designing titanium-based dental implants and aseptic techniques, infection remains as the most common complication after implantation surgeries. Although, having a weakened immune system or systematic diseases is not seen as contraindicated for dental implants anymore, controlling the immune system is required to avoid surgical site infections after implantation. These patients have to control the surgical site infections by taking a high daily dose of oral antibiotics after dental implantation. The antibiotics oral administration has many side effects such as gastrointestinal symptoms, skin rashes and thrush. Coating antibiotics on the biomaterials surface could be a promising solution to reduce these disadvantages through locally releasing antibiotics in a controlled manner. The aim of this study was to investigate the effects of doxycycline coating layer on titanium-zirconium alloy surfaces in vitro and in vivo. In our previous studies, we demonstrated the chemical presence of doxycycline layer in vitro. In this study, we examined its physical presence using field emission scanning electron microscope and confocal microscope. We also analyzed its controlled released manner using Nano-Drop UV Vis spectrometer. After in vitro characterization of the coating layer, we evaluated its effects on the implant osseointegration in dogs and rabbits. The histological and histomorphometrical results exhibited no significant difference between doxycycline coated and uncoated groups regarding the implants osseointegration and biocompatibility for dental applications. Therefore, coating a doxycycline layer on TiZr implants could be favorable for reducing or removing the antibiotics oral administration after the implantation surgery.

Histological analysis of loaded zirconia and titanium dental implants: an experimental study in the dog mandible.

OBJECTIVE: To assess whether or not peri-implant soft tissue dimensions and hard tissue integration of loaded zirconia implants are similar to those of a titanium implant. MATERIALS AND METHODS: In six dogs, two one-piece zirconia implants (VC, ZD), a two-piece zirconia implant (BPI) and a control one-piece titanium implant (STM) were randomly placed. CAD/CAM crowns were cemented at 6 months. Six months later, animals were killed and histomorphometric analyses were performed, including: the level of the mucosal margin, the extent of the peri-implant mucosa, the marginal bone loss and the bone-to-implant contact (BIC). Means of outcomes variables were calculated together with their corresponding 95% confidence intervals. RESULTS: In general, the mucosal margin was located coronally to the implant shoulder. The buccal peri-implant mucosa ranged between 2.64 ± 0.70 mm (VC) and 3.03 ± 1.71 mm (ZD) (for all median comparisons p > 0.05). The relative marginal bone loss ranged between 0.65 ± 0.61 mm (BPI) and 1.73 ± 1.68 mm (ZD) (buccal side), and between 0.55 ± 0.37 mm (VC) and 1.69 ± 1.56 mm (ZD) (lingual side) (p > 0.05). The mean BIC ranged between 78.6% ± 17.3% (ZD) and 87.9% ± 13.6% (STM) without statistically significant differences between the groups (p > 0.05). CONCLUSIONS: One- and two-piece zirconia rendered similar peri-implant soft tissue dimensions and osseointegration compared to titanium implants that were placed at 6 months of loading. Zirconia implants, however, exhibited a relatively high fracture rate.

In vivo behaviour of two different biphasic ceramic implanted in mandibular bone of dogs.

Alloplastic calcium phosphate bone substitutes such as hydroxyapatite (HA) and tricalcium phosphate (TCP) have been studied extensively due to their composition closely resembling the inorganic phase of bone tissue. On the same way, by manipulating the HA/TCP ratio it may be possible to change the substitution rate and the bioactivity of these materials, an advantage which has brought them to clinical use in oral and orthopaedic surgery. In this work, we evaluated the histological response in bone of two biphasic calcium phosphate ceramics by varying the proportion of their components. All premolars of 6 beagle dogs were removed from both sides of the mandible. Three months later, four cylinders composed of 85% HA and 15% beta-TCP (BCP 1) were implanted in the right side of mandible and other four cylinders composed of 15% HA and 85% beta-TCP (BCP 2) were implanted in the left side of mandible of dogs for 4, 12 ad 26 weeks, respectively. Two dogs were used in each time point. The histological study indicated that both biphasic ceramic were biocompatible. The earlier and more quantity of bone formed in BCP 2 than in BCP 1 suggested that the first one had a higher osteoinductive potential than the second one in mandibular bone. The resorption of the phosphate phase and the subsequent migration of bone into the resorbed portions were detected in both biphasic ceramics although two processes appeared faster in BCP 2 than in BCP 1. These dates conclude that varying the components of our biphasic ceramic we improve its osteoinductive potential.