Guided bone regeneration in implant dentistry: Basic principle, progress over 35 years, and recent research activities

Bone augmentation procedures are frequent today in implant patients, since an implant should be circumferentially anchored in bone at completion of bone healing to have a good long-term stability. The best documented surgical technique to achieve this goal is guided bone regeneration (GBR) utilizing barrier membranes in combination with bone fillers. This clinical review paper reflects 35 years of development and progress with GBR. In the 1990s, GBR was developed by defining the indications for GBR, examining various barrier membranes, bone grafts, and bone substitutes. Complications were identified and reduced by modifications of the surgical technique. Today, the selection criteria for various surgical approaches are much better understood, in particular, in post-extraction implant placement. In the majority of patients, biodegradable collagen membranes are used, mainly for horizontal bone augmentation, whereas bioinert PTFE membranes are preferred for vertical ridge augmentation. The leading surgeons are using a composite graft with autogenous bone chips to accelerate bone formation, in combination with a low-substitution bone filer to better maintain the augmented bone volume over time. In addition, major efforts have been made since the millenium change to reduce surgical trauma and patient morbidity as much as possible. At the end, some open questions related to GBR are discussed.

Mid-Term Results of Single-Stage Surgery for Patients with Chronic Osteomyelitis Using Antibiotic-Loaded Resorbable PerOssal® Beads

This retrospective study reports on the treatment of chronic osteomyelitis with local debridement combined with PerOssal^®. The diagnosis of chronic osteomyelitis was confirmed in all cases and classified according to the Cierny-Mader (C-M) classification. The primary outcome was the eradication of infection at a minimum of one year after surgery. A total of 93 patients (median age: 40 years) were included. The most represented sites were the femur (24, 25.8%) and tibia (52, 55.9%). Twenty-six patients (28.0%) had significant local or systemic comorbidities (C-M Class B hosts). According to anatomic type, 31 cases were type I, 13 type II, 21 type III and 28 type IV. Vancomycin was added to PerOssal^® in most cases (80, 86.0%). In 24 (25.8%) cases, Vancomycin and Rifampicin were combined. In 32 (34.4%) cases, intraoperative cultures were negative. Staphylococcus aureus was isolated in 39 (63.9%) patients, and Gram-negative bacteria were isolated in 12 cases. The median follow-up was 21 months (range 12-84). A total of 21 (22.6%) patients developed an infection recurrence (IR) after a median follow-up of 11 months (range: 1-47). PerOssal^® holds several practical advantages compared to other bone void fillers. Thus, due to its good biocompatibility and sufficient antibiotic release, it represents a viable adjuvant treatment in chronic osteomyelitis.

Functionalization with a Polyphenol-Rich Pomace Extract Empowers a Ceramic Bone Filler with In Vitro Antioxidant, Anti-Inflammatory, and Pro-Osteogenic Properties

Oral diseases and periodontitis in particular are a major health burden worldwide, because of their association with various systemic diseases and with conditions such as peri-implantitis. Attempts have been made over the years to reverse bone loss due to the host disproportionate inflammatory response and to prevent failure of dental implants. To this end, the use of biomaterials functionalized with molecules characterized by anti-inflammatory and antioxidant properties could represent a new frontier for regenerating functional periodontal tissues. In this study, a new ceramic granulated biomaterial, named Synergoss Red (SR), functionalized with a polyphenolic mixture extracted from pomace of the Croatina grape variety, is introduced. Following a preliminary in-depth characterization of the extract by HPLC analysis and of the biomaterial surface and composition, we performed evaluations of cytocompatibility and a biological response through in vitro assays. The anti-inflammatory and antioxidant properties of the identified phenolic molecules contained in SR were shown to downregulate inflammation in macrophages, to stimulate in osteoblast-like cells the expression of genes involved in deposition of the early bone matrix, and to mitigate bone remodeling by decreasing the RANKL/OPG ratio. Thanks to its cytocompatibility and assorted beneficial effects on bone regeneration, SR could be considered an innovative regenerative approach in periodontal therapy.

In vivo approach on femur bone regeneration of white rat (Rattus norvegicus) with the use of hydroxyapatite from cuttlefish bone (Sepia spp.) as bone filler

Background:

Hydroxyapatite (HA) from bovine bone has been widely used as bone filler in many fractures cases. HA can also be made from cuttlefish bone (Sepia spp.) that has abundant availability in Indonesia and contains 84% CaCO₃, which is a basic ingredient of HA. However, research on the effects of HA from cuttlefish bone on bone regeneration parameters has not been done yet.

Aim:

This study aimed to determine femur bone regeneration of white rats (Rattus norvegicus) through the use of HA from cuttlefish bone (Sepia spp.) as bone filler.

Materials and Methods:

HA was made using the hydrothermal method by mixing 1M aragonite (CaCO₃) from cuttlefish bone and 0.6 M NH₄H₂PO₄ at 200°C for 12 h followed by sintering at 900°C for 1 h. In vivo test was carried out in three groups, including control group, bovine bone-derived HA group, and cuttlefish bone-derived HA group. The generation of femur bone was observed through the number of osteoblasts, osteoclasts, woven bone, lamellar bone, havers system, and repair bone through anatomical pathology test for 28 days and 56 days.

Results:

Anatomical pathology test results are showed that administration of bovine bone-derived HA and cuttlefish bone-derived HA increased the number of osteoblasts, osteoclasts, woven bone, lamellar bone, havers system, and bone repair at recuperation of 56 days. Statistical test using Statistical Package for the Social Sciences with Kruskal–Wallis and Mann–Whitney U-test was resulted in significant differences between the bovine bone-derived HA control group and the cuttlefish-derived HA control group. There was no significant difference toward the indication of bone formation through the growth of osteoblasts, osteoclasts, woven bone, lamellar bone, havers system, and bone repair in the bovine bone-derived HA and cuttlefish bone-derived HA groups.

Conclusion:

It can be concluded that cuttlefish bone-derived HA has the potential as bone filler based on the characteristics of bone regeneration through in vivo test.

Biological Evaluation of Flexible Polyurethane/Poly l-Lactic Acid Composite Scaffold as a Potential Filler for Bone Regeneration

Degradable bone graft substitute for large-volume bone defects is a continuously developing field in orthopedics. With the advance in biomaterial in past decades, a wide range of new materials has been investigated for their potential in this application. When compared to common biopolymers within the field such as PLA or PCL, elastomers such as polyurethane offer some unique advantages in terms of flexibility. In cases of bone defect treatments, a flexible soft filler can help to establish an intimate contact with surrounding bones to provide a stable bone-material interface for cell proliferation and ingrowth of tissue. In this study, a porous filler based on segmented polyurethane incorporated with poly l-lactic acid was synthesized by a phase inverse salt leaching method. The filler was put through in vitro and in vivo tests to evaluate its potential in acting as a bone graft substitute for critical-sized bone defects. In vitro results indicated there was a major improvement in biological response, including cell attachment, proliferation and alkaline phosphatase expression for osteoblast-like cells when seeded on the composite material compared to unmodified polyurethane. In vivo evaluation on a critical-sized defect model of New Zealand White (NZW) rabbit indicated there was bone ingrowth along the defect area with the introduction of the new filler. A tight interface formed between bone and filler, with osteogenic cells proliferating on the surface. The result suggested polyurethane/poly l-lactic acid composite is a material with the potential to act as a bone graft substitute for orthopedics application.

The Development of a Novel Bone Filler, Titanium Wire Ball

In designing bone fillers, hardness has heretofore not been a major concern. Fillers are typically very hard and thus often accelerate the collapse of the adjacent bones. We developed a novel, relatively soft bone filler, whose hardness is similar to the human cancellous bone. The structure is simple: a 0.14-mm-diameter pure titanium wire was rolled and folded with both ends buried in the central portion, resulting in a ball of 4-mm diameter with 83% internal void ratio, having 300-500 μm internal gaps. The balls are chemically washed in an acidic solution at the end of the manufacturing process. We call this new filling device titanium wire balls (TWBs). We implanted TWBs into the medial condyle of the right tibiae of twelve adult Japanese white rabbits, and histologically evaluated the results. Four weeks after implantation, the spaces in the TWBs were fully calcified; the TWBs, the calcified tissues in them and the cancellous bones surrounding them were all connected with each other. In conclusion, we developed a novel bone filler that has similar hardness to the human cancellous bone and an 83% internal void ratio, with 300-500 μm internal gaps. Four weeks after implantation, the spaces in TWBs were fully calcified and connected to the surrounding cancellous bones.