Aim: To investigate the effect of three treatment modalities on the gain of keratinized tissue (KT) at tooth and implant sites in dogs. Materials and Methods: In five dogs, the distal roots of the mandibular second, third and fourth premolars were extracted, while the mesial roots were maintained. After 2 months of healing, implants were placed with KT excision. After another 2 months of healing, free gingival grafts, collagen-based matrices and apically positioned flap only were applied. The height of KT was measured during implant placement, immediately before soft-tissue grafting and after 10, 30 and 60 days. Results: Two months after KT excision, spontaneous KT regrowth was greater at tooth sites than at implant sites (median, 2.0 mm vs. 1.1 mm). The outcomes of softtissue grafting at implant sites favoured the free gingival graft treatment, with a greater final median height (5.0-5.5 mm) and increase in KT (4.0-4.2 mm). Locations of the recipient sites significantly influenced KT regeneration at both tooth and implant sites. Conclusions: At implant sites, the free gingival graft treatment led to higher KT regeneration. At tooth sites, however, the differences between the three treatment modalities seemed clinically irrelevant.

zxA higher number of studies evaluated various types of bone graft materials for the lateral window approach due to the excessiveness over the crestal approach. Autogenous bone was the first one to be investigated, because of its osteogenic, osteoinductive and osteoconductive properties (Boyne & James, 1980); however, the disadvantages were also reported, such as high surgical morbidity, patients' discomfort and unpredictable resorption rate, resulting in decrease of the grafted site volume (Hallman & Thor, 2008). Therefore, bone substitutes have been considered as an alternative to compensate

Background: Local delivery agents (LDA) have the advantage of delivering the antibiotics at high concentrations to the targeted sites. However, the constant flow of gingival crevicular fluids and saliva may restrict their efficacy. Therefore, the drug sustainability and pharmacodynamic properties of any proposed LDA should be evaluated. Methods: Four dental implants were placed unilaterally in the edentulous mandible of six beagle dogs. Peri-implantitis were experimentally induced using silk-ligatures. Each implant was randomly allocated to receive one of the following four treatments: (i) MC (Chitosan-alginate (CA) minocycline), (ii) MP (CA-without minocycline), (iii) PG (Polyacrylate-glycerin minocycline), and (iv) Control (mechanical debridement only). Mechanical therapies and LDAs were administered into the gingival sulcus two times at a 4-week interval. Drug sustainability as well as clinical, radiographical, and immunohistochemical (IHC) analyses were conducted to evaluate the efficacies of treatments. Results: Reduced mean probing depth was observed in all of the test groups after the second delivery. A minimal marginal bone level change was observed during the treatment period (MP (−0.06 ± 0.53 mm) to PG (−0.25 ± 0.42 mm)). The distribution of IHC cell marker analysis of all targeted antibodies ranged from 6.34% to 11.33%. All treatment outcomes between the test groups were comparable. A prolonged retention of LDA was observed from CA microspheres (MC and MP) at both administrations (p < 0.017) and prolonged sustainability of bacteriostatic effect was observed from MC compared to PG after the second administration (p < 0.05). Conclusions: Prolonged retention of CA microspheres was observed and the longer bacteriostatic effect was observed from the MC group. Mechanical debridement with adjunct LDA therapy may impede peri-implantitis progression, however, prolonged drug action did not lead to improved treatment outcome.

Aim: To investigate new bone (NB) formation by using bone-block substitute materials with/without recombinant human bone morphogenetic protein-2 (rhBMP-2).Materials and Methods: Three synthetic bone-block substitute materials [biphasic calcium phosphate (BCP); nanostructured hydroxyapatite (NH); 3D-printed tricalcium phosphate/hydroxyapatite (3DP)] and one xenogeneic deproteinized bovine bone mineral (DBBM) block substitute were affixed to rabbit calvarium using osteosynthesis screws, either with rhBMP-2 (n = 12) or without rhBMP-2 (n = 16). At 2 or 12 weeks (n = 6 with rhBMP-2 and n = 8 without rhBMP-2 for each week), histologic, histomorphometric and microcomputed tomography analyses were performed. Results:The application of rhBMP-2 increased NB formation in all experimental groups at both weeks. DBBM resulted in a greater area of NB compared with synthetic blocks either with or without rhBMP-2 at 2 weeks (2.8 ± 0.9 vs. 1.4 ± 0.5-1.9 ± 1.4 mm 2 ; 1.4 ± 1.0 vs. 0.6 ± 0.3-0.9 ± 0.5 mm 2 ) and without rhBMP-2 at 12 weeks (3.0 ± 0.8 vs. 1.7 ± 0.7-2.6 ± 1.5 mm 2 ) (p > 0.05). NB formation did not differ significantly for DBBM and the three types of synthetic block with rhBMP-2 at 12 weeks (4.5 ± 2.0 vs.3.8 ± 0.7-5.1 ± 1.1 mm 2 ; p > 0.05).Conclusions: rhBMP-2 enhanced NB in all blocks. DBBM blocks yielded more NB than synthetic blocks without rhBMP-2. The application of rhBMP-2 appears to compensate for differences in late healing. K E Y W O R D Salveolar ridge augmentation, bone morphogenetic protein-2, bone regeneration, bone substitutes Clinical RelevanceScientific rationale for study: There is a dearth of studies comparing the bone regeneration properties of different bone-block substitute materials. Information regarding the effects of rhBMP-2 on bone substitute blocks is also scarce. Principal findings: New bone formation (NB) without rhBMP-2 favoured the xenogeneic blocks over the synthetic blocks. NB formation with rhBMP-2 favoured xenogeneic blocks during the | 1127 LIM et aL. How to cite this article: Lim H-C, Paeng K-W, Jung U-W, Benic GI. Effectiveness of xenogeneic and synthetic bone-block substitute materials with/without recombinant human bone morphogenetic protein-2: A preclinical study using a rabbit calvarium model.

Objectives To determine the volume stability of a sinus augmented with a collagenated bovine bone mineral (CBBM) in case of an intact or perforated Schneiderian membrane (SM). Materials and Methods A bilateral sinus augmentation procedure was performed in eight rabbits. The SM was intentionally perforated in one side (SMP group), while it remained intact in contra‐lateral side (control group) and the same amount of CBBM was then grafted. At 12 weeks, the animals were euthanized for radiographic and histomorphometric analyses. Results The augmented volume did not differ significantly between the two groups: 262.2 ± 32.1 mm3 in SMP group and 261.9 ± 48.5 mm3 in the control group (p = .959). There was no significant difference in the total augmented area: 24.7 ± 5.2 mm2 in SMP group and 23.2 ± 2.9 mm2 in the control group (p = .773). The areas of newly formed bone also did not differ significantly between the two groups, but was significantly lower at the centre of the augmented region than in the region of the surgical window in both groups (p < .05). Conclusion A perforation of the SM in a rabbit model does neither impact the augmented volume nor new bone formation following grafting of the sinus with a CBBM.