Clinical Relevance of Integrated Developmental Research for Dental Implants

Abstract

The topic “clinical relevance of integrated developmental research for dental implants” was initially addressed at a multidisciplinary symposium during the 93rd General Session & Exhibition of the International Association for Dental Research on March 11, 2015, in Boston, Massachusetts, USA. The objective of this meeting consisted in discussing the optimal workflow for the development of a dental implant from the initial bench design to in vivo implantation at the clinical level. As a study case, attendees decided to share views on and confer about a new tapered implant. This special issue of Advances in Dental Research reflects the multiple outcomes of the discussions that took place during the above symposium and the multiple exchanges and chats that followed. The opening publication consists in a narrative review. The authors of the first paper, relying on undisputed clinical experience, describe that the relationship that exists among implant surface, primary stability, thread configuration, body shape, and type of bony bed has to be considered to lessen treatment times by decreasing the healing period during which osseointegration is established (Wilson et al. 2016). From this discussion, the concept of initial stability, which incorporates all the aforementioned parameters (including primary stability), clearly emerges. Consequently the 2 subsequent papers by Boyan et al. (2016) and Bonfante and Coelho (2016) deepen, respectively, the significance of implant surface and mechanical properties on osseointegration and their long-term maintenance. Boyan et al. (2016) insist on how surface design affects mesenchymal cell response and differentiation into the osteoblast lineage, as recent studies have highlighted the importance of hierarchical micro-/nanosurface roughness, as well as surface roughness in combination with surface wettability. Cell surface receptors recognize topographic and biological changes in the surface and downstream signaling pathways accordingly (i.e., the noncanonical Wnt5a pathway, which has been implicated in osteoblastic differentiation on titanium implant surfaces). Moreover, recently conducted studies on the differences in biological responses to implants based on sex, age, and clinical factors advocate for patient-specific implant designs. Bonfante and Coelho (2016) identify the complexity of investigating varied implant designs, related bone response, area of implantation, implant bulk material, restoration, abutments and related screws, fixation mode (screwed, fixed, or a combination), and horizontal implant-abutment matching geometry. They are concerned by the number of and interplay among variables in dental implant treatment and outline that this presents a challenge to clinical trials attempting to answer questions in a timely, unbiased, and economically feasible fashion. Their manuscript critically appraises the most common mechanical testing methods used to characterize the implant-prosthesis complex. It attempts to provide insight into the process of construction of an informed database of clinically relevant questions regarding preclinical evaluation of implant biomechanics and failure mechanisms. The use of such methodologies as single load to failure, fatigue life, fatigue limit, and step-stress accelerated life testing is pragmatically discussed with emphasis on their weaknesses and strengths. The fourth publication, by Dard et al. (2016), defends the concept of integrative performance analysis applied to a novel bone-level tapered implant. They propose successively conducting bone type–specific drill procedures that ensure maximum insertion torque values within the range of 15 to 80 N·cm when measured by maximum insertion torque and resonance frequency analysis. The biomechanical behavior of the taperwalled implant was assessed in combination with a bone type– specific drill procedure in natural bone of various types (porcine ribs and mandible) and an in vitro model using polyurethane foam blocks of variable density (bone types 1 through 4). This approach intends to predict primary stability upon implantation. Furthermore, the authors show that finite elemental analysis supports the effectiveness of incorporating an optimized drill procedure for a given implant type and bone quality. Stavropoulos and Cochran (Stavropoulos et al. 2016) offer an extensive concluding contribution by evaluating, in a preclinical in vivo model, whether a protocol involving slight underpreparation of the implant site may have an effect on aspects of osseointegration as compared with the standard protocol, with taping and profiling of the marginal aspect of the implant osteotomy. Half of the implants were immediately loaded, and the rest were submerged. Significantly lower average insertion torque values were recorded for the standard drilling protocol group 630947 ADRXXX10.1177/0022034516630947Advances in Dental ResearchIntegrated Developmental Research for Dental Implants research-article2016