1 – Osseointegration: Hierarchical designing encompassing the macrometer, micrometer, and nanometer length scales
Paulo G. Coelhoa, Ryo Jimbod, Nick Tovar, Estevam A. Bonfantee
0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Objective: Osseointegration has been a proven concept in implant dentistry and orthopedics for decades. Substantial efforts for engineering implants for reduced treatment time frames have focused on micrometer and most recently on nanometer length scale alterations with negligible attention devoted to the effect of both macrometer design alterations and surgical instrumentation on osseointegration. This manuscript revisits osseointegration addressing the individual and combined role of alterations on the macrometer, micrometer, and nanometer length scales on the basis of cell culture, preclinical in vivo studies, and clinical evidence.
Methods: A critical appraisal of the literature was performed regarding the impact of dental implant designing on osseointegration. Results from studies with different methodological approaches and the commonly observed inconsistencies are discussed.
Results: It is a consensus that implant surface topographical and chemical alterations can hasten osseointegration. However, the tailored combination between multiple length scale design parameters that provides maximal host response is yet to be determined.
Significance: In spite of the overabundant literature on osseointegration, a proportional inconsistency in findings hitherto encountered warrants a call for appropriate multivariable study designing to ensure that adequate data collection will enable osseointegration maximization and/or optimization, which will possibly lead to the engineering of endosteal implant designs that can be immediately placed/loaded regardless of patient dependent conditions.
2 – The effect of implant design on insertion torque and immediate micromotion
Amilcar C. Freitas Jr, Estevam A. Bonfante, Gabriela Giro, Malvin N. Janal, Paulo G. Coelho
Clin. Oral Impl. Res. 10.1111/j.1600-0501.2010.02142.x c_ 2011 John Wiley & Sons A/S
Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs.
Material and methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (901 cut at the apex, tap design); and (3) Blossomt (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 901 by a digital torque gauge. Controlled lateral loads of 10N followed by increments of 5 up to 100N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction.
Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M _ standard deviation [SD]1/464.1 _ 26.8, 139.4 _ 17.2, and 205.23 _ 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M _ SD1/4530 _ 57.7, 585.9 _ 82.4, and 782.33 _ 269.4 mm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossomt, fluted and non-fluted design groups, respectively.
Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.
3 – Laboratory Torque Testing, Histomorphometric and Biomechanical Testing or Self-Tapping Implant Thread Designs.
S. Lin, R. Granato, C. Marin, M. Suzuki, E. Bonefante, G. Giro, P.G. Coelho New York, NY.
2010, Academy of Osseointegration, Annual Meeting, P222
Objective: to determine the in vitro insertion torque, and the early in vivo performance of self-tapping implant thread designs.
Methods: The self-tapping implant thread designs were used: Blossom (B), Classic Cutting Flutes (DT), and no cutting classic design (C). All implants were 4mm diameter and 10mm length. The implants were inserted in a 3.2mm osteotomy in a foam material and the torque as a function of number of turns was recorded. For the in vivo part of the experiment, the implants were bilaterally placed in a 3.2mm osteotomy in the proximal tibia of 6 dogs, remaining for 2 and 4 weeks in vivo (6 per limb). Following euthanisation, half the implants were torqued to interface failure and the other half were nondecalcified processed for bone-to-implant contact determination. Statistical analysis was performed at 95% confidence level by ANOVA considering BIC and Torque as dependent variables.
Results: The self-tapping implant designs presented lower insertion torque values compared to the C group. While up to 6 turns the B and DT implants presented similar torque vales, lower values were observed for the B values up to 12 turns. Time in vivo and implant design did not have an influence in torque to interface failure and BIC.
Conclusion: While the self-tapping implants presented lower insertion torque values, no differences in BIC and torque to interface failures were detected between different implant tread designs at early implantation times.
4 – The impact of a modified cutting flute implant design on osseointegration
R. Jimbo, N. Tovar, C. Marin, H. S. Teixeira, R. B. Anchieta, L. M. Silveira, M. N. Janal, J. A. Shibli, P. G. Coelho:
Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx. # 2014, In-Press, International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd.
Information concerning the effects of the implant cutting flute design on initial stability and its influence on osseointegration in vivo is limited. This study evaluated the early effects of implants with a specific cutting flute design placed in the sheep mandible.
Forty-eight dental implants with two different macro-geometries (24 with a specific cutting flute design – Blossom group; 24 with a self-tapping design – DT group) were inserted into the mandibular bodies of six sheep; the maximum insertion torque was recorded. Samples were retrieved and processed for histomorphometric analysis after 3 and 6 weeks. The mean insertion torque was lower for Blossom implants (P < 0.001).
No differences in histomorphometric results were observed between the groups. At 3 weeks, P = 0.58 for bone-to-implant contact (BIC) and P = 0.52 for bone area fraction occupied (BAFO); at 6 weeks, P = 0.55 for BIC and P = 0.45 for BAFO. While no histomorphometric differences were observed, ground sections showed different healing patterns between the implants, with better peri-implant bone organization around those with the specific cutting flute design (Blossom group).
Implants with the modified cutting flute design had a significantly reduced insertion torque compared to the DT implants with a traditional cutting thread, and resulted in a different healing pattern.