15. Mar. 2012
Pages: 7 - 77
no abstract available
This paper reports on the results of a structured review of the literature concerning in vivo molecular assessment of osseointegrated endosseous dental implants. A search of electronic databases was performed up to and including August 2011. Thirty articles met the inclusion criteria. A descriptive evaluation and analysis of the gene expression data concerning the process of osseointegration were performed. Broad consensus was observed among the study results, perhaps as a result of the similar targeted gene expression events. More recent investigations using gene arrays or gene profiling techniques offer new insights into the fundamental molecular events that support the osseointegration process. Evidence for the influence of surface topography on osteogenesis and osteoinduction has been reported. Additional investigations are required to further solidify the functional associations between individual or orchestrated gene expression events and the clinical result of osseointegration.
Keywords: gene profiling, molecular regulation, osseointegration, osteogenesis, osteoinduction
With the advent of nanotechnology, an opportunity exists for the engineering of new dental implant materials. Metallic dental implants have been successfully used for decades, but they have shortcomings related to osseointegration and mechanical properties that do not match those of bone. Absent the development of an entirely new class of materials, faster osseointegration of currently available dental implants can be accomplished by various surface modifications. To date, there is no consensus regarding the preferred method(s) of implant surface modification, and further development will be required before the ideal implant surface can be created, let alone become available for clinical use. Current approaches can generally be categorized into three areas: ceramic coatings, surface functionalization, and patterning on the micro- to nanoscale. The distinctions among these are imprecise, as some or all of these approaches can be combined to improve in vivo implant performance. These surface improvements have resulted in durable implants with a high percentage of success and long-term function. Nanotechnology has provided another set of opportunities for the manipulation of implant surfaces in its capacity to mimic the surface topography formed by extracellular matrix components of natural tissue. The possibilities introduced by nanotechnology now permit the tailoring of implant chemistry and structure with an unprecedented degree of control. For the first time, tools are available that can be used to manipulate the physicochemical environment and monitor key cellular events at the molecular level. These new tools and capabilities will result in faster bone formation, reduced healing time, and rapid recovery to function.
Keywords: bone formation, coatings, dental implants, hydroxyapatite, nanotechnology, surface topography
Purpose: Previous studies have demonstrated the capacity of a designed proline-rich synthetic peptide to stimulate osteoblast differentiation and biomineralization in vitro. Therefore, the aim of the present study was to evaluate the osseointegration capacity of titanium (Ti) implants coated with these peptides in a rabbit model.
Materials and Methods: Four calibrated defects were prepared in the tibiae of three New Zealand rabbits, and the defects were randomized into a test group (peptide-modified machined Ti implant) and a control group (unmodified machined Ti implant). The performance in vivo was investigated after 4 weeks of implantation by real-time reverse transcriptase polymerase chain reaction of bone and inflammatory markers, microcomputed tomographic analysis of mineralized bone, and histologic examination.
Results: The peptides adsorbed in agglomerates on Ti and underwent a change in secondary structure upon adsorption, which induced an increase in surface wettability. Gene expression markers indicated that peptide-coated Ti implants had significantly decreased mRNA levels of tartrateresistant acid phosphatase. A trend toward increased osteocalcin in the peri-implant bone tissue was also seen. Bone morphometric and histologic parameters did not show significant differences, although the peptide group showed a higher percentage of new bone histologically.
Conclusions: Proline-rich peptides have potential as a biocompatible coating for promoting osseointegration of Ti implants by reducing bone resorption.
Keywords: dental implants, gene expression, histology, microcomputed tomography, osseointegration, proline-rich peptide
Purpose: This study describes the use of an innovative dynamic implant valve approach (DIVA) for dental implant placement and sinus augmentation procedures.
Materials and Methods: The DIVA implant system was tested in vitro for leakage and mechanical fatigue. A closed sinus elevation procedure with a gel-type bone substitute was performed using the DIVA implant in a swine model (n = 6). Implants were placed and evaluated radiographically and histologically.
Results: Elevation of the maxillary sinus membrane and augmentation were performed in a simple, minimally invasive fashion. Histologic analyses demonstrated complete sealing of the DIVA implant and excellent osseointegration.
Conclusion: The DIVA can be used as a simplified viable option for dental implantation and augmentation procedures. Hermetic sealing of this implant system, which features an inner screw, renders it safe.
Keywords: dental endoscopy, implant dentistry, maxillary sinus elevation
Purpose: This study compared the 1-year success rates of immediately loaded dental implants to delayed loaded implants, regardless of the surgical technique (flapless or conventional full-thickness flap) and regardless of extraction time. It also examined whether the surgical technique had an influence on the success rate of the immediately loaded implants.
Materials and Methods: A total of 344 dental implants, some with a new expanded winged-thread design, were placed in 155 patients; 53% of the implants were immediately loaded. Of the immediately loaded implants, 68.9% were placed with a flapless surgical technique and 88% were placed in extraction sites. Pocket depth, mobility, bleeding on probing, presence of erythema, pain, or radiolucency around the implants, as well as clinical findings, were recorded. Implants were followed from placement through definitive restoration. Descriptive, univariate, and multivariate analyses using clustered marginal approach of the Cox proportional hazards model were applied.
Results: Of the 344 implants in the study, 10 (2.9%) failures were recorded, 7 of which were immediately loaded; however, there was no significant difference in failure rates between the immediate and delayed loading groups. Seven of the implants that failed were placed with a flapless (extraction site) technique; however, there was no significant difference in the failure rates between the flapless versus full-thickness flap technique in immediately loaded implants.
Conclusions: The clinical success of immediately loaded implants after 1 year showed no difference from the success rate of delayed loaded implants. The implantation procedure (flapless versus conventional flap) or extraction time also had no influence on the success rate of the immediately loaded implants.
Keywords: dental implants, flapless implant placement, immediate loading, implant failure, implant success, open flap
Purpose: A retrospective study was performed to evaluate the feasibility of simultaneous use of immediately loaded zygomatic and mandibular implants for full maxillomandibular restoration.
Materials and Methods: A total of 40 zygomatic and 112 conventional implants were placed in 19 edentulous and partially edentulous patients and restored with full-arch acrylic resin prostheses within 3 hours of surgery. Implant insertion torque values were between 35 and 45 Ncm.
Results: During the 1-year follow-up period, none of the 19 patients experienced implant or prosthesis failures. The patients did not experience any sinus infections or any other surgical complications from the performed procedures.
Conclusion: Zygomatic and conventional implants can be simultaneously placed in the maxilla and mandible and successfully loaded with an acrylic resin prosthesis using the All-on-Four concept.
Keywords: dental implants, immediate loading, insertion torque, zygomatic implants
Purpose: To report on the use of angled implants placed into the vomer/nasal crest to support a complete-arch maxillary prosthesis.
Materials and Methods: Consecutive patients were treated with the All-on-Four concept to restore the maxillary dentition. When bone volume in the subnasal region was inadequate, angled implants were placed into the vomer/nasal crest area to support the restoration. All implants were loaded immediately.
Results: One hundred consecutive maxillary All-on-Four patients were treated over a period of 2 years. Four hundred six implants were placed; 12 were inserted into the vomer/nasal crest area. One year later, at definitive restoration, the 12 vomer implants were found to be osseointegrated without bone loss or instability.
Conclusions: Midline maxillary bone volume at the nasal crest appeared to be a viable alternative to the lateral nasal rim when subnasal bone was deficient. Vomer implants allowed for immediate function or were sometimes used as a rescue implant when an anterior implant failed.
Keywords: All-on-Four protocol, M point, nasal crest, vomer implant, vomer/nasal crest bone mass, V point
no abstract available
no abstract available