A Randomized Controlled Trial of Guided Bone Regeneration for Peri-Implant Dehiscence Defects with Two Anorganic Bovine Bone Materials Covered by Titanium Meshes

The aim of this study is to compare two low-temperature sintered anorganic bovine bone materials (ABBMs), Bio-Oss (Geistlich, Wolhusen, Switzerland) and A-Oss (Osstem, Seoul, Korea), for GBR in dehiscence defects. A single implant was placed simultaneously with GBR in the buccal or bucco-proximal osseous defect by double-layering of inner allograft and outer ABBM, covered by a preformed ultrafine titanium mesh and an absorbable collagen membrane. Grafted volume changes were evaluated by cone-beam computed tomography, taken preoperatively (T0), immediately after implant surgery (T1), after re-entry surgery (T2), and after delivery of the final restoration (T3). The density of the regenerated bone was assessed by measuring the probing depth on the buccal mid-center of the mesh after removing the mesh at T2. Postoperative sequelae were also recorded. Grafted volume shrinkage of 46.0% (0.78 ± 0.37 cc) and 40.8% (0.79 ± 0.33 cc) in the Bio-Oss group (8 patients) and A-Oss group (8 patients), respectively, was observed at T3 (p < 0.001). There were no significant differences in grafted volume changes according to time periods or bone density between the two groups. Despite postoperative mesh exposure (3 patients), premature removal of these exposed meshes and additional grafting was not necessary, and all implants were functional over the 1-year follow-up period. Both ABBMs with titanium meshes showed no significant difference in the quantity and density of the regenerated bone after GBR for peri-implant defects.

In vivo evaluation of 3D printed polycaprolactone composite scaffold and recombinant human bone morphogenetic protein-2 for vertical bone augmentation with simultaneous implant placement on rabbit calvaria

This study evaluated 3D printed polycaprolactone (PCL) composite scaffold and recombinant human bone morphogenetic protein-2 (rhBMP-2), loaded either onto a PCL composite scaffold or implant surface, for vertical bone augmentation with implant placement. Three-dimensional printed PCL frames were filled with powdered PCL, hydroxyapatite, and β-tricalcium phosphate. RhBMP-2 was loaded to the PCL composite scaffolds and implant surfaces, and rhBMP-2 release was quantified for 21 days. Experimental implants were placed bilaterally on 20 rabbit calvaria, and the PCL composite scaffolds were vertically augmented. The randomly allocated experimental groups were divided by carrier and rhBMP-2 dosage as no rhBMP-2 (control), 5 μg rhBMP-2 loaded to PCL composite (Scaffold/rhBMP-2[5 μg]), 5 μg rhBMP-2 loaded to implant (Implant/rhBMP-2[5 μg]), 30 μg rhBMP-2 loaded to PCL composite (Scaffold/rhBMP-2[30 μg]), and 30 μg rhBMP-2 loaded to implant (Implant/rhBMP-2[30 μg]). Histologic and histometric analyses were conducted after 8 weeks. In both scaffold-loading and implant-loading, rhBMP-2 released initially rapidly, then slowly and constantly. Released rhBMP-2 totaled 23.02 ± 1.03% and 24.69 ± 1.14% in the scaffold-loaded and implant-loaded groups, respectively. There were no significant differences in histologic bone-implant contact (%). Peri-implant bone density (%) was significantly higher in the Scaffold/rhBMP-2(30 μg) and Implant/rhBMP-2(30 μg) groups. Total bone density (%) was not significantly different between the Scaffold/rhBMP-2(5 μg), Implant/rhBMP-2(5 μg), and control groups, or between the Scaffold/rhBMP-2(30 μg) and Implant/rhBMP-2(30 μg) groups, but was significantly higher in the Scaffold/rhBMP-2(30 μg) and Implant/rhBMP-2(30 μg) groups than in the controls. Three-dimensional printed PCL composite scaffold with rhBMP-2 produced vertical osteogenesis and osseointegration, regardless of rhBMP-2 loading to the PCL composite scaffold or implant surface.

Pre-Clinical Models in Implant Dentistry: Past, Present, Future

Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.

Enhanced bone formation of calvarial bone defects by low-intensity pulsed ultrasound and recombinant human bone morphogenetic protein-9: a preliminary experimental study in rats

OBJECTIVES

The aim of this study was to evaluate the combined effects of recombinant human bone morphogenetic protein - 9 (rhBMP-9) loaded onto absorbable collagen sponges (ACS) and low-intensity pulsed ultrasound (LIPUS) on bone formation in rat calvarial defects.

MATERIALS AND METHODS

Circular calvarial defects were surgically created in 18 Wistar rats, which were divided into LIPUS-applied (+) and LIPUS-non-applied (-) groups. The 36 defects in each group received ACS implantation (ACS group), ACS with rhBMP-9 (rhBMP-9/ACS group), or surgical control (control group), yielding the following six groups: ACS (+/-), rhBMP-9/ACS (+/-), and control (+/-). The LIPUS-applied groups received daily LIPUS exposure starting immediately after surgery. At 4 weeks, animals were sacrificed and their defects were investigated histologically and by microcomputed tomography.

RESULTS

Postoperative clinical healing was uneventful at all sites. More new bone was observed in the LIPUS-applied groups compared with the LIPUS-non-applied groups. Newly formed bone area (NBA)/total defect area (TA) in the ACS (+) group (46.49 ± 7.56%) was significantly greater than that observed in the ACS (-) (34.31 ± 5.68%) and control (-) (31.13 ± 6.74%) groups (p < 0.05). The rhBMP-9/ACS (+) group exhibited significantly greater bone volume, NBA, and NBA/TA than the rhBMP-9/ACS (-) group (2.46 ± 0.65 mm³ vs. 1.76 ± 0.44 mm³, 1.25 ± 0.31 mm² vs. 0.88 ± 0.22 mm², and 62.80 ± 11.87% vs. 42.66 ± 7.03%, respectively) (p < 0.05). Furthermore, the rhBMP-9/ ACS (+) group showed the highest level of bone formation among all groups.

CONCLUSION

Within their limits, it can be concluded that LIPUS had osteopromotive potential and enhanced rhBMP-9-induced bone formation in calvarial defects of rats.

CLINICAL RELEVANCE

The use of rhBMP-9 with LIPUS stimulation can be a potential bone regenerative therapy for craniofacial/peri-implant bone defects.

Membranes for Guided Bone Regeneration: A Road from Bench to Bedside

Bone resorption can negatively influence the osseointegration of dental implants. Barrier membranes for guided bone regeneration (GBR) are used to exclude nonosteogenic tissues from influencing the bone healing process. In addition to the existing barrier membranes available on the market, a growing variety of membranes for GBR with tailorable physicochemical properties are under preclinical evaluation. Hence, the aim of this review is to provide a comprehensive description of materials used for GBR and to report the main industrial and regulatory aspects allowing the commercialization of these medical devices (MDs). In particular, a summary of the main attributes defining a GBR membrane is reported along with a description of commercially available and under development membranes. Finally, strategies for the scaling-up of the manufacturing process and the regulatory framework of the main MD producers (USA, EU, Japan, China, and India) are presented. The description of the regulatory approval process of GBR membranes is representative of the typical path that medium- to high-risk MDs have to follow for an effective medical translation, which is of fundamental importance to increase the impact of biomedical research on public health.

Effect of BMP-2 Adherent to Resorbable Sutures on Cartilage Repair: A Rat Model of Xyphoid Process

Meniscal tears are often seen in orthopedic practice. The current strategy for meniscal repair has only had limited success with a relatively high incidence of re-operative rate. This study evaluates the therapeutic effects of Bone morphogenetic protein-2 (BMP-2) soaked sutures for cartilage repair, using a rat model of xyphoid healing. Vicryl-resorbable sutures were presoaked in BMP-2 solutions prior to animal experimentation. Rat xyphoid process (an avascular hyaline cartilage structure) was surgically ruptured followed by repair procedures with regular suture or with sutures that were pre-soaked in BMP-2 solutions. In vitro assessment indicated that presoaking the Vicryl-resorbable sutures with 10 µg/mL BMP-2 resulted in a sustained amount of the growth factor release up to 7 days. Histological analysis suggested that application of this BMP-2 soaked suture on the rat xyphoid process model significantly improved the avascular cartilage healing compared to non-soaked control sutures. In conclusion, data here confirm that the rat xyphoid process repair is a reproducible and inexpensive animal model for meniscus and other cartilage repair. More importantly, coating of BMP-2 on sutures appears a potential avenue to improve cartilage repair and regeneration. Further study is warranted to explore the molecular mechanisms of this strategy.