Computer guided root tip extraction and implant placement: A clinical report.

Extraction of a residual root tip and implant placement can be challenging because of the complexity and invasiveness of the procedure. Improvised application of a guided implant surgery may avoid such challenges. This clinical report presents an innovative technique combining a 3-dimensionally printed surgical guide with conventional instrumentation for a residual root tip extraction in a minimally invasive and predictable way.

Bone tissue response following local drug delivery of bisphosphonate through titanium oxide nanotube implants in a rabbit model.

OBJECTIVES: The objective of this study was to evaluate whether surface chemistry-controlled TiO2 nanotube structures may serve as a local drug delivery system for zoledronic acid improving implant-bone support. METHODS: Twenty-four screw-shaped Ti implants with surface chemistry-controlled TiO2 nanotube structures were prepared and divided into a zoledronic acid-formatted test and a native control group. The implants were inserted into contra-lateral femoral condyles in 12 New Zealand White rabbits. Bone support was evaluated using resonance frequency analysis (RFA) and removal torque (RTQ), as well as histometric analysis following a 3-weeks healing interval. RESULTS: Zoledronic acid-formatted TiO2 nanotube test implants showed significantly improved implant stability and osseointegration measured using RFA and RTQ compared with control (p < 0.05), and showed significantly enhanced new bone formation within the root of the threads compared with control (p < 0.05). CONCLUSIONS: TiO2 nanotube implants may prove to be a significant delivery system for drugs or biologic agents aimed at supporting local bone formation. Additional study of candidate drugs/agents, optimized dosage and release kinetics is needed prior to evaluation in clinical settings.

Experimental evidence for interfacial biochemical bonding in osseointegrated titanium implants.

OBJECTIVES: (i) To identify and quantify an interfacial biochemical bond and the bonding strength of osseointegrated implants with bioactive titanium oxide chemistry, ATiO(x)B (A, metal cations; TiO(x) , titanium oxides/hydroxides; B, non-metal anions) and (ii) to provide quantitative evidence for the biochemical bond theory of osseointegration proposed by Sul et al. for description and explanation of why and how the implants with ATiO(x) B surface oxide chemistry may exhibit a significantly stronger bone response, in spite of the fact that the roughness values approached zero, or were equivalent to or significantly lower than those of the control implants. MATERIALS AND METHODS: We applied a newly developed biochemical bond measurement (BBM) method to model implant surfaces that were "perfectly" smooth nanotopography near-zero roughness as the constant parameter, and used the bioactive surface chemistry of titanium oxide, ATiOx B chemistry as a variable parameter in rabbit tibiae for 10 weeks. In this manner, we determined an interfacial biochemical bond and quantified its bonding strength. RESULTS: The increase in biochemical bond strengths of the test implant relative to the control implant was determined to be 0.018 (±0.008) MPa (0.031 vs 0.021 MPa, n = 10) for tensile strength and 8.9 (±6.1) Ncm (33.0 vs 24.1 Ncm, n = 10) for removal torque. Tensile and removal torque show strong correlation in the Pearson test (r = 0.901, P ≤ 0.001). In addition, histomorphometric measurements including bone-to-metal-contact (BMC, P = 0.007), bone area and newly formed bone showed significant increases in the mean values for ATiO(x) B chemistry (P = 0.007, n = 10). Biochemical bond theory states that the surface oxide chemistry, ATiO(x) B must have more electrical and chemical molecular polarity that fractionally charges the surfaces denoted as δ(+) and δ(-) and leads to electrostatic and electrodynamic interactions with the bone healing cascade, eventually leading to the formation of biochemical bonding at the bone/implant interface. CONCLUSIONS: The present study has provided quantitative evidence for biochemical bond theory of osseointegration of implants with bioactive surface oxide chemistry, ATiO(x) B. The theory of biochemical bonds may provide a scientific rationale pertinent to recent emerging trends and technologies for surface chemistry modifications of implants.

Evaluation of an injectable rhGDF-5/PLGA construct for minimally invasive periodontal regenerative procedures: a histological study in the dog.

AIM: To evaluate the injectability, biocompatibility, safety, and periodontal wound healing/regeneration following application of a novel bioresorbable recombinant human growth/differentiation factor-5 (rhGDF-5)/poly(lactic-co-glycolic acid) (PLGA) construct. MATERIAL AND METHODS: Periodontal pockets (3 x 6 mm, width x depth) were surgically created over the buccal roots of the second and fourth mandibular pre-molars in eight adult Hound Labrador mongrel dogs. Surgeries including injection of the rhGDF-5/PLGA construct into the pockets were sequenced that four animals provided 2-/4-week and four animals 6-/8-week observations of sites receiving rhGDF-5/PLGA or serving as sham-surgery control. RESULTS: The rhGDF-5/PLGA construct was easy to prepare and apply. Approximately 0.2 ml (93 microg rhGDF-5)/tooth was used. Clinical and radiographic healing was exemplary without adverse events. Healing was characterized by a non-specific connective tissue attachment, acellular/cellular cementum, periodontal ligament (PDL), bone regeneration, and a junctional epithelium. PLGA fragments were observed in 4/7, 2/8, and 1/8 sites at 2, 4, and 6 weeks, respectively. Associated inflammatory reactions exhibited no limiting effect on periodontal wound healing/regeneration. Root resorption/ankylosis was not observed. Bone formation showed apparent increased maturity (lamellar bone) at 6 weeks in sites receiving rhGDF-5/PLGA compared with the control. Both protocols exhibited significant increases in PDL, cementum, and bone regeneration over time, without significant differences between treatments. In time, PDL and cementum regeneration was twofold greater for the control at 4 weeks (p=0.04) while increased bone formation was observed at sites receiving rhGDF-5/PLGA (p<0.01). CONCLUSIONS: In conclusion, the rhGDF-5/PLGA construct appears to be a safe technology for injectable, ease-of-use application of rhGDF-5-stimulated periodontal wound healing/regeneration. Additional work to optimize the polymer carrier and rhGDF-5 release kinetics/dose might be required before evaluating the efficacy of this technology in clinical settings using minimally invasive approaches.

Periodontal wound healing/regeneration following the application of rhGDF-5 in a beta-TCP/PLGA carrier in critical-size supra-alveolar periodontal defects in dogs.

AIM: The objective of this study was to evaluate the effect of a novel recombinant human GDF-5 (rhGDF-5) construct intended for onlay and inlay indications on periodontal wound healing/regeneration. METHODS: Contralateral, surgically created, critical-size, 6-mm, supra-alveolar periodontal defects in five adult Hound Labrador mongrel dogs received rhGDF-5 coated onto beta-tricalcium phosphate (beta-TCP) particles and immersed in a bioresorbable poly(lactic-co-glycolic acid) (PLGA) composite or the beta-TCP/PLGA carrier alone (control). The rhGDF-5 and control constructs were moulded around the teeth and allowed to set. The gingival flaps were then advanced; flap margins were adapted 3-4 mm coronal to the teeth and sutured. The animals were euthanized at 8 weeks post-surgery when block biopsies were collected for histometric analysis. RESULTS: Healing was generally uneventful. A few sites exhibited minor exposures. Three control sites and one rhGDF-5 site (in separate animals) experienced more extensive wound dehiscencies. The rhGDF-5 and control constructs were easy to apply and exhibited adequate structural integrity to support the mucoperiosteal flaps in this challenging onlay model. Limited residual beta-TCP particles were observed at 8 weeks for both rhGDF-5/beta-TCP/PLGA and beta-TCP/PLGA control sites. The rhGDF-5/beta-TCP/PLGA sites showed significantly greater cementum (2.34 +/- 0.44 versus 1.13 +/- 0.25 mm, p=0.02) and bone (2.92 +/- 0.66 versus 1.21 +/- 0.30 mm, p=0.02) formation compared with the carrier control. Limited ankylosis was observed in four of five rhGDF-5/beta-TCP/PLGA sites but not in control sites. CONCLUSIONS: Within the limitations of this study, the results suggest that rhGDF-5 is a promising candidate technology in support of periodontal wound healing/regeneration. Carrier and rhGDF-5 dose optimization are necessary before further advancement of the technology towards clinical evaluation.