Optimizing autologous bone contribution to implant osseointegration

Trephination-based autonomous robotic surgery for dental implant placement: A proof of concept

OBJECTIVES

To present a novel drilling protocol of trephine osteotomy technique for autologous bone grafting with simultaneous implant placement using an autonomous robotic system.

METHODS

The novel protocol consists of 1) preoperative procedures: marker fabrication and fixation, data acquisition, and preoperative planning; 2) intraoperative procedures: registration and calibration, and osteotomy and implant placement performed by an autonomous dental implant robot; 3) postoperative procedures: CBCT acquisition and accuracy assessment.

RESULT

The protocol was an effective method for implant osteotomy, with no reported intraoperative complications. The implant surgery was successfully completed, and autogenous bone was obtained. Meanwhile, the accuracy of implant placement was clinically acceptable, with minor deviations.

CONCLUSIONS

Trephination-based robotic surgery can be successfully implemented in implant osteotomy, which might replace freehand implant surgery and conventional drilling protocol. However, further clinical studies are necessary.

CLINICAL SIGNIFICANCE

The main finding of this case is a potential alternative for preserving autogenous bone during implant surgery.

Emerging factors affecting peri-implant bone metabolism

Implant dentistry has evolved to the point that standard implant osseointegration is predictable. This is attributed in part to the advancements in material sciences that have led toward improvements in implant surface technology and characteristics. Nonetheless, there remain several cases where implant therapy fails (specifically at early time points), most commonly attributed to factors affecting bone metabolism. Among these patients, smokers are known to have impaired bone metabolism and thus be subject to higher risks of early implant failure and/or late complications related to the stability of the peri-implant bone and mucosal tissues. Notably, however, emerging data have unveiled other critical factors affecting osseointegration, namely, those related to the metabolism of bone tissues. The aim of this review is to shed light on the effects of implant-related factors, like implant surface or titanium particle release; surgical-related factors, like osseodensification or implanted biomaterials; various drugs, like selective serotonin reuptake inhibitors, proton pump inhibitors, anti-hypertensives, nonsteroidal anti-inflammatory medication, and statins, and host-related factors, like smoking, diet, and metabolic syndrome on bone metabolism, and aseptic peri-implant bone loss. Despite the infectious nature of peri-implant biological complications, these factors must be surveyed for the effective prevention and management of peri-implantitis.

A novel technique to harvest bone autografts with mild local hyperthermia and enhanced osteogenic bone quality: a preclinical study in dogs

BACKGROUND

Guided bone regeneration (GBR) involves collecting bone autografts with high bio-quality and efficiency. The current non-irrigated low-speed drilling has been limited for broader application in bone autograft harvest due to its low efficiency, inability to conduct buccal cortical perforation, and dependence on simultaneous implant placement. Increasing the drilling speed helps improve the efficiency but may incur thermal-mechanical bone damage. Most studies have addressed thermal reactions during bone drilling on non-vital models, which is irrelevant to clinical scenarios. Little has been known about bone's in vivo thermal profiles under non-irrigated higher-speed drilling and its influences on the resulting bone chips.

AIM

A novel technique for bone harvest and cortical perforation via in-situ non-irrigated higher-speed drilling was proposed and investigated for the first time.

METHODS

The third mandible premolars of eight beagles were extracted and healed for three months. Sixteen partial edentulous sites (left and right) were randomized into four groups for bone autograft harvest without irrigation: chisel, 50 rpm drilling, 500 rpm drilling, and 1000 rpm drilling. Bone chips were harvested on the buccal plates of the missing tooth. An infrared camera and an implantable thermocouple collaboratively monitored in vivo real-time bone temperature at the drilling sites. In vitro performances of cells from bone chips, including cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, mRNA transcriptional level of osteogenic genes and heat shock protein 70 (HSP-70), and HSP-70 expression at the protein level were also studied.

RESULTS

500 rpm produced mild local hyperthermia with a 2-6 °C temperature rise both on the cortical surface and inside the cortical bone. It also held comparable or enhanced cell performances such as cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, and osteogenic genes expression.

CONCLUSIONS

In-situ non-irrigated higher-speed drilling at 500 rpm using a screw drill is versatile, efficient, and thermal friendly and improves the bio-quality of bone chips. Our novel technique holds clinical translational potential in GBR application.

Osseointegration in relation to drilling speed in the preparation of dental implants sites: A systematic review

STATEMENT OF PROBLEM

The drilling speed used for preparing dental implants may affect bone-implant contact (BIC), implant stability quotient (ISQ), and bone area fraction occupancy (BAFO). Different rotational speeds and the presence or absence of irrigation during site preparation have been investigated, but an established protocol for achieving the best osseointegration results is lacking.

PURPOSE

The purpose of this systematic review was to investigate the influence of drill rotational speed on bone drilling for dental implant placement and its relationship with osseointegration.

MATERIAL AND METHODS

This review included the preferred reporting items for systematic reviews and meta-analyses (PRISMA) and was registered in the international prospective register of systematic reviews (PROSPERO) database. Electronic searches were performed in the MEDLINE (PubMed), Scopus, Science Direct, and Embase databases. The risk of bias was analyzed by using the systematic review center for laboratory animal experimentation (SYRCLE).

RESULTS

A total of 1282 articles were found, and after removing duplicates and applying the eligibility criteria to in vivo articles on animals that addressed drilling speed and its relationship to osseointegration, 8 articles were selected for analysis. Of these, 5 articles showed no statistical differences, and 3 others showed significantly better osseointegration results by analyzing the parameters of BIC, BAFO, ISQs, and pull-out forces (PoFs). In all selected articles, high-speed drilling was performed with irrigation.

CONCLUSIONS

Although drilling speed seems to affect bone perforation, no definitive protocol was found in the literature consulted. The results vary depending on the combination of different factors, including bone type, irrigation, and drilling speed.

Oral Cell Lysates Reduce the Inflammatory Response of Activated Macrophages

Necrotic cell damage occurs as a consequence of invasive dental procedures. Loss of membrane integrity being the hallmark of necrotic cells leads to the release of cytoplasmic and membranous components. Macrophages are predestined to respond to lysates originating from necrotic cells. Here, we implement necrotic lysates from human gingival fibroblasts, HSC2, and TR146 oral epithelial cell lines, and RAW264.7 macrophage cell lines to be tested for their potential to modulate the inflammatory response of macrophages. To this aim, necrotic cell lysates were prepared by sonication or freezing/thawing of the respective cell suspension. Necrotic cell lysates were tested for their potential to modulate the lipopolysaccharide (LPS)-induced expression of inflammatory cytokines using RAW264.7 macrophages as a bioassay. We show here that all necrotic cell lysates, independent of the origin and the preparation way, reduced the expression of IL1 and IL6 in LPS-induced RAW264.7 macrophages, most obviously shown for TR146 cells. This finding was supported in a bioassay when macrophages were exposed to poly (I:C) HMW, an agonist of TLR-3. Consistently, all necrotic lysates from gingival fibroblasts, HSC2, TR146, and RAW264.7 cells reduced the nuclear translocation of p65 in LPS-exposed macrophages. This screening approach supports the overall concept that necrotic cell lysates can modulate the inflammatory capacity of macrophages.

Nano-Based Drug Delivery Systems for Periodontal Tissue Regeneration

Periodontitis is a dysbiotic biofilm-induced and host-mediated inflammatory disease of tooth supporting tissues that leads to progressive destruction of periodontal ligament and alveolar bone, thereby resulting in gingival recession, deep periodontal pockets, tooth mobility and exfoliation, and aesthetically and functionally compromised dentition. Due to the improved biopharmaceutical and pharmacokinetic properties and targeted and controlled drug release, nano-based drug delivery systems have emerged as a promising strategy for the treatment of periodontal defects, allowing for increased efficacy and safety in controlling local inflammation, establishing a regenerative microenvironment, and regaining bone and attachments. This review provides an overview of nano-based drug delivery systems and illustrates their practical applications, future prospects, and limitations in the field of periodontal tissue regeneration.

A WNT protein therapeutic accelerates consolidation of a bone graft substitute in a pre-clinical sinus augmentation model

AIM

Autologous bone grafts consolidate faster than bone graft substitutes (BGSs) but resorb over time, which compromises implant support. We hypothesized that differences in consolidation rates affected the mechanical properties of grafts and implant stability, and tested whether a pro-osteogenic protein, liposomal WNT3A (L-WNT3A), could accelerate graft consolidation.

MATERIALS AND METHODS

A transgenic mouse model of sinus augmentation with immunohistochemistry, enzymatic assays, and histology were used to quantitatively evaluate the osteogenic properties of autografts and BGSs. Composite and finite element modelling compared changes in the mechanical properties of grafts during healing until consolidation, and secondary implant stability following remodelling activities. BGSs were combined with L-WNT3A and tested for its osteogenic potential.

RESULTS

Compared with autografts, BGSs were bioinert and lacked osteoprogenitor cells. While in autografted sinuses, new bone arose evenly from all living autograft particles, new bone around BGSs solely initiated at the sinus floor, from the internal maxillary periosteum. WNT treatment of BGSs resulted in significantly higher expression levels of pro-osteogenic proteins (Osterix, Collagen I, alkaline phosphatase) and lower levels of bone-resorbing activity (tartrate-resistant acid phosphatase activity); together, these features culminated in faster new bone formation, comparable to that of an autograft.

CONCLUSIONS

WNT-treated BGSs supported faster consolidation, and because BGSs typically resist resorption, their use may be superior to autografts for sinus augmentation.

An Osteotomy Tool That Preserves Bone Viability: Evaluation in Preclinical and Clinical Settings

The main objectives of this work were to assess the efficiency, ease-of-use, and general performance of a novel osseoshaping tool based on first-user clinical experiences and to compare these observations with preclinical data generated in rodents using a miniaturized version of the instrument. All patients selected for the surgery presented challenging clinical conditions in terms of the quality and/or quantity of the available bone. The presented data were collected during the implant placement of 15 implants in 7 patients, and included implant recipient site (bone quality and quantity) and ridge evaluation, intra-operative handling of the novel instrument, and the evaluation of subsequent implant insertion. The instrument was easy to handle and was applied without any complications during the surgical procedure. Its use obviated the need for multiple drills and enabled adequate insertion torque in all cases. This biologically driven innovation in implant site preparation shows improvements in preserving vital anatomical and cellular structures as well as simplifying the surgical protocol with excellent ease-of-use and handling properties.

A novel system exploits bone debris for implant osseointegration

BACKGROUND

Bone debris generated during site preparation is generally evacuated with irrigation; here, we evaluated whether retention of this autologous material improved the rate of peri-implant bone formation.

METHODS

In 25 rats, a miniature implant system composed of an osseo-shaping tool and a tri-oval-shaped implant was compared against a conventional drill and round implant system. A split-mouth design was used, and fresh extraction sockets served as implant sites. Histology/histomorphometry, immunohistochemistry, and microcomputed tomography (μCT) imaging were performed immediately after implant placement, and on post-surgery days 3, 7, 14, and 28.

RESULTS

Compared with a conventional drill design, the osseo-shaping tool produced a textured osteotomy surface and viable bone debris that was retained in the peri-implant environment. Proliferating osteoprogenitor cells, identified by PCNA and Runx2 expression, contributed to faster peri-implant bone formation. Although all implants osseointegrated, sites prepared with the osseo-shaping tool showed evidence of new peri-implant bone sooner than controls.

CONCLUSION

Bone debris produced by an osseo-shaping tool directly contributed to faster peri-implant bone formation and implant osseointegration.