Abutment Macro and Micro-design for the Improvement of the Soft Tissue Interface
- Discuss the importance of both hard and soft tissue stability for implant success.
- Identify the technique-associated factors that can lead to marginal bone loss.
- Identify abutment design-associated factors that can lead to peri-implant bone loss.
- Evaluate new abutment designs and their impact on both hard and soft tissue stability over time.
How do abutment design and surface modification affect the behavior of soft and hard tissue over time? Dr. Mesquida opens this lecture by presenting the biology of tissue integration. Once an incision is opened and an implant and abutment are placed, there is rapid colonization of epithelial tissue, and within days hemidesmosomes appear, then the basal lamina generates an epithelium. Over the course of a few days, granulation tissue forms, and connective tissue appears, which provides protection of the underlying bone from bacterial down growth and infection. This soft tissue barrier is referred to as supracrestal fibers, and also known as biological width. Having an average length of about 3 to 4 mm, it can be separated into two components: the connective tissue area that is right above the bone or the implant platform (about 1.5 mm) and the junctional epithelium (about 2 mm).
Dr. Mesquida discusses surgical techniques and other relevant factors, such as abutment materials and design, and their favorability for the restoration and the gingival environment, and tissue thickness. The type of abutment implant connection plays a crucial role in tissue integration, as does the relationship between the horizontal diameter of the abutment and the horizontal diameter of the implant, which establishes the platform-switching concept. It results in the stability of soft tissue, a reduced incidence of peri-implantitis, and a better aesthetic outcome. Most implant-abutment connections available today are external hex, internal hex, and flat-to-flat connections, also called tube-in-tube connections. The question is whether these different connections influence the supracrestal fibers that will form. The goal is to have the supracrestal fibers above the implant connection.
Bone loss at the supracrestal complex is a common issue faced in implantology, caused by bone remodeling, epithelial downgrowth, and its migration to the apical area. Theories regarding the cause include bacterial load, gap size, and micro-movements at the connection. Looking at the evidence, it is clear that the size of the gap, unless clinically unacceptable, is irrelevant. What is relevant is the micromovement between the abutment and the implant. Dr. Mesquida presents clinical videos showing the differences in micromotion between an external hex connection and an internal connection. Both in-vivo and clinical studies show a 1.5 to 2 mm bone loss can be expected with external hex connections during the first year of function.
According to the Albrektsson criteria, an implant with 1 to 1.5 mm of bone loss in the first year of function is still considered a success. But, should this be considered sufficient today? Studies show that bone loss around implants with a conical connection is significantly less. Dr. Mesquida presents a case involving a patient with a failing mandibular incisor; immediate implant placement is not possible because 4-5 mm of the apical bone volume necessary to stabilize the implant is not available. In this case, he decided to extract the tooth, augment the site with a bone graft, and place an implant with an internal connection and platform-switching capability. At the two-year follow-up, despite the modern connection and platform switching, a small degree of bone loss is noted under critical observation. However, clinically, the outcome is satisfactory, and the patient is satisfied with the outcome.
Can we improve upon some degree of undesirable bone loss, however small? Dr. Mesquida recommends looking at new innovations in implant-abutment connections and presents one such innovation, a trioval implant system (N1™, Nobel Biocare). The tight seal of connection restricts any micromovement between parts of the implant system. In discussing this innovation, Dr. Mesquida dispels misconceptions about bone-to-implant contact and primary stability in relation to implant design. Circular implants, in general, tend to have a high initial bone-to-implant contact. When an implant is placed in a round osteotomy, the entire implant is surrounded by or in contact with bone. For the same reason, the peri-implant strains are evenly distributed. Clinical studies show that a high insertion torque will induce osteocytic cell death and apoptosis, thus compromising primary stability. During this time, the implant should not be loaded because it is surrounded by some degree of necrosis.
The new trioval implant system could promote tissue integration and widens eligibilty for immediate implants. At placement of the trioval implant, contact between the implant wall and the bone occurs mainly at the so-called minimal areas, the triangle vertex. At the same time, there is no contact at the so-called maximal areas. Consequently, less pressure is applied, and less osteoclastic activity is induced. As a result, Dr. Mesquida notes, osseointegration should be faster and, presenting an ideal scenario for immediate implant placement. An immediate implant is usually placed on a Type 1 socket, with a requisite minimum of 1 mm of palatal bone and a 2 mm space surrounding the implant at the buccal aspect in order to be able to graft that area. Dr. Mesquida demonstrates the advantage of a trioval implant for this clinical indication. Considering these prerequisites and the literature on buccal lingual dimensions of extraction sockets, he shows 58.1% of central incisors in the anterior premaxillary region cannot be treated with a cylindrical implant of 4 mm because the implant would be too wide. However, the remaining space buccally is larger when the trioval implant is used. This increases the proportion of patients eligible for immediate implant placement in an extraction socket, resulting in more patient treatments. Dr. Mesquida illustrates this with a clinical case, in which a patient with a failing central incisor and complete loss of the buccal palate was treated with an immediate implant using guided surgery and 3D planning to utilize maximum bone available and additional xenograft and tissue graft.
Turning to the topic of platform switching, the concept was discovered by chance when restorative components in the matched dimension were not available, and abutments with a smaller dimension were used. Less marginal bone loss was observed with the smaller abutments, and so, the effect of platform switching was observed. There are two theories behind the platform switching concept: one relates to the aforementioned micro-movements between the abutment and implant, which result in a disruption to the microfibers that seal the implant. The second theory is the biological theory. This involves a small inflammatory infiltrate that is always observed around two-piece implants. When this inflammatory infiltrate has been displaced or moves inward towards the connection, the distance to the bone increases. A 2010 systematic review addressing platform switching shows that a greater degree of mismatch results in even less bone loss. This mismatch can only be limited as it would otherwise result in mechanical problems. The critical value that the investigators of the 2010 study defined as clinically relevant is that the difference should be at least 0.4 mm.
In terms of surgical and prosthetic techniques, Dr. Mesquida presents the various options, including submerged implants, healing abutment, and immediate provisionalization. Presenting several studies showing that there is no difference in terms of bone loss, he concludes that all surgical techniques work in the same manner. But what about the prosthetic techniques? Dr.Mesquida invites the audience to review the steps performed until a final restoration is placed. In general, an implant has been placed, and a healing abutment has been used to avoid the risk of a re-opening. In the presented case of a second molar, the abutment is removed, and a pink band of connective tissues is observed at the very base of the implant platform, and epithelial tissue or junctional epithelium is observed at the top. By removing the abutment, the seal of the tissues was broken, a new wound opened, and with it, a potential portal of entry for bacterial contamination. As early as 1997, a study by Abrahamsson demonstrated the bone loss induced by abutment removal. Dr. Mesquida illustrates the typical number of disconnections in a clinical case of a failing anterior central incisor. He extracted the tooth, placed an implant, placed a temporary crown, performed a connective tissue graft, and restored the case with a zirconia abutment. Counting the disconnections, he noted 13 disconnections. And the presented case may have been a favorable case, as the patient showed a thick biotype. The clinical implications led Dr. Mesquida to apply the “one abutment one time” concept, in which an abutment is placed at the time of surgery and never removed. Studies show that when the “one abutment one time” concept is applied, an average bone loss of around 0.2 to 0.5 mm is observed.
What impact does abutment material have? When looking at abutments, four things are critical:
- Bacterial adhesion
- Soft tissue cell affinity
When considering abutments, tissue thickness also comes into play. Modern studies show that at tissue thickness below 2 mm, bone loss of about 1.2 mm is observed, and at tissue thickness above 2 millimeters, bone loss begins to decrease significantly. A concept introduced some years ago is the On1 concept, for which Dr. Mesquida was one of the early researchers. In his ongoing prospective study, Dr. Mesquida and co-authors are following 72 patients with single tooth replacements: 36 implants with On1 base and 36 with implant level restorations. Despite challenges following the patients during COVID restrictions, results revealed a statistically significant difference in favor of the one abutment one time concept, the On1 base restored group.
The next frontier for innovation to improve tissue integration, identified by Dr. Mesquida, is the abutment surface. Even when all the previously discussed concepts of platform switching, one abutment one time, proper implant position, and biocompatibility of all materials are applied, some bone loss occurs. What might be the next opportunity for innovation? For Dr. Mesquida, it's the surface chemistry of the abutment. He proposes incorporating a surface that is favorable for fibroblast attachment, that is bacteriostatic and therefore does not support bacterial colonization. Until now, little literature is available on this topic, especially long-term studies. In his study, Dr. Mesquida found, when comparing machined and anodized abutments (Xeal™, Nobel Biocare), that anodized abutments tended to have less recession. He is now investigating two clinical questions: is there any difference in bone loss and is there a difference in periodontal parameters? In contrast to a study by Hall, Dr. Mesquida observed 15% of machined abutments had bleeding on probing, while 80 % of the anodized abutments had bleeding on probing. Furthermore, using a visual analog score (VAS), patients were asked to report pain during probing on a scale of 0 to 100. Patients with machined abutments answered an average of 14, while patients with anodized abutments consistently felt slightly more pain. Dr. Mesquida asks, what could be the reason for this? He concludes that more bleeding on probing and an increase in pain perception could indicate better mucointegration, i.e. better integration of the abutment into the soft tissue.
 Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res. 1991 Apr-Jun;2(2):81-90. doi: 10.1034/j.1600-0501.1991.020206.x. PMID: 1809403.
 de Sanctis M, Vignoletti F, Discepoli N, Muñoz F, Sanz M. Immediate implants at fresh extraction sockets: an experimental study in the beagle dog comparing four different implant systems. Soft tissue findings. J Clin Periodontol. 2010 Aug 1;37(8):769-76. doi: 10.1111/j.1600-051X.2010.01570.x. Epub 2010 Jun 1. PMID: 20528965.
 Abrahamsson I, Berglundh T, Sekino S, Lindhe J. Tissue reactions to abutment shift: an experimental study in dogs. Clin Implant Dent Relat Res. 2003;5(2):82-8. doi: 10.1111/j.1708-8208.2003.tb00188.x. PMID: 14536042.
 Nevins M, Nevins ML, Schupbach P, Fiorellini J, Lin Z, Kim DM. The impact of bone compression on bone-to-implant contact of an osseointegrated implant: a canine study. Int J Periodontics Restorative Dent. 2012 Dec;32(6):637-45. PMID: 23057052.
 Zuhr, O., & Hürzeler, M. (2012). Plastic-esthetic periodontal and implant surgery: a microsurgical approach. Quintessence.
 Lambert F, Lecloux G, Léonard A, Sourice S, Layrolle P, Rompen E. Bone regeneration using porous titanium particles versus bovine hydroxyapatite: a sinus lift study in rabbits. Clin Implant Dent Relat Res. 2013 Jun;15(3):412-26. doi: 10.1111/j.1708-8208.2011.00374.x. Epub 2011 Aug 4. PMID: 21815992.
 Linkevicius T, Linkevicius R, Alkimavicius J, Linkeviciene L, Andrijauskas P, Puisys A. Influence of titanium base, lithium disilicate restoration and vertical soft tissue thickness on bone stability around triangular-shaped implants: A prospective clinical trial. Clin Oral Implants Res. 2018 Jul;29(7):716-724. doi: 10.1111/clr.13263. Epub 2018 May 31. PMID: 29855100.
 Broggini N, McManus LM, Hermann JS, Medina RU, Oates TW, Schenk RK, Buser D, Mellonig JT, Cochran DL. Persistent acute inflammation at the implant-abutment interface. J Dent Res. 2003 Mar;82(3):232-7. doi: 10.1177/154405910308200316. PMID: 12598555.
 Broggini N, McManus LM, Hermann JS, Medina R, Schenk RK, Buser D, Cochran DL. Peri-implant inflammation defined by the implant-abutment interface. J Dent Res. 2006 May;85(5):473-8. doi: 10.1177/154405910608500515. PMID: 16632764.
 Hermann JS, Schoolfield JD, Schenk RK, Buser D, Cochran DL. Influence of the size of the microgap on crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged implants in the canine mandible. J Periodontol. 2001 Oct;72(10):1372-83. doi: 10.1902/jop.2001.72.10.1372. PMID: 11699479.
 Zipprich H, Weigl P, Ratka C, Lange B, Lauer HC. The micromechanical behavior of implant-abutment connections under a dynamic load protocol. Clin Implant Dent Relat Res. 2018 Oct;20(5):814-823. doi: 10.1111/cid.12651. Epub 2018 Jul 24. PMID: 30039915.
 Adell R, Eriksson B, Lekholm U, Brånemark PI, Jemt T. Long-term follow-up study of osseointegrated implants in the treatment of totally edentulous jaws. Int J Oral Maxillofac Implants. 1990 Winter;5(4):347-59. PMID: 2094653.
 Jemt T, Carlsson L, Boss A, Jörneús L. In vivo load measurements on osseointegrated implants supporting fixed or removable prostheses: a comparative pilot study. Int J Oral Maxillofac Implants. 1991 Winter;6(4):413-7. PMID: 1820310.
 Berglundh T, Abrahamsson I, Lindhe J. Bone reactions to longstanding functional load at implants: an experimental study in dogs. J Clin Periodontol. 2005 Sep;32(9):925-32. doi: 10.1111/j.1600-051X.2005.00747.x. PMID: 16104954.
 Jung RE, Pjetursson BE, Glauser R, Zembic A, Zwahlen M, Lang NP. A systematic review of the 5-year survival and complication rates of implant-supported single crowns. Clin Oral Implants Res. 2008 Feb;19(2):119-30. doi: 10.1111/j.1600-0501.2007.01453.x. Epub 2007 Dec 7. PMID: 18067597.
 Kielbassa AM, Martinez-de Fuentes R, Goldstein M, Arnhart C, Barlattani A, Jackowski J, Knauf M, Lorenzoni M, Maiorana C, Mericske-Stern R, Rompen E, Sanz M. Randomized controlled trial comparing a variable-thread novel tapered and a standard tapered implant: interim one-year results. J Prosthet Dent. 2009 May;101(5):293-305. doi: 10.1016/S0022-3913(09)60060-3. PMID: 19410064.
 Yin X, Li J, Hoffmann W, Gasser A, Brunski JB, Helms JA. Mechanical and Biological Advantages of a Tri-Oval Implant Design. J Clin Med. 2019 Mar 28;8(4):427. doi: 10.3390/jcm8040427. PMID: 30925746; PMCID: PMC6517945.
 Zhang W, Skrypczak A, Weltman R. Anterior maxilla alveolar ridge dimension and morphology measurement by cone beam computerized tomography (CBCT) for immediate implant treatment planning. BMC Oral Health. 2015 Jun 10;15:65. doi: 10.1186/s12903-015-0055-1. PMID: 26059796; PMCID: PMC4460662.
 Lazzara RJ, Porter SS. Platform switching: a new concept in implant dentistry for controlling postrestorative crestal bone levels. Int J Periodontics Restorative Dent. 2006 Feb;26(1):9-17. PMID: 16515092.
 Schrotenboer J, Tsao YP, Kinariwala V, Wang HL. Effect of platform switching on implant crest bone stress: a finite element analysis. Implant Dent. 2009 Jun;18(3):260-9. doi: 10.1097/ID.0b013e31819e8c1d. PMID: 19509536.
 Canay S, Akça K. Biomechanical aspects of bone-level diameter shifting at implant-abutment interface. Implant Dent. 2009 Jun;18(3):239-48. doi: 10.1097/ID.0b013e318198ffd1. PMID: 19509534.
 Maeda Y, Sogo M, Tsutsumi S. Efficacy of a posterior implant support for extra shortened dental arches: a biomechanical model analysis. J Oral Rehabil. 2005 Sep;32(9):656-60. doi: 10.1111/j.1365-2842.2005.01478.x. PMID: 16102078.
 Cappiello M, Luongo R, Di Iorio D, Bugea C, Cocchetto R, Celletti R. Evaluation of peri-implant bone loss around platform-switched implants. Int J Periodontics Restorative Dent. 2008 Aug;28(4):347-55. PMID: 18717373.
 Prosper L, Redaelli S, Pasi M, Zarone F, Radaelli G, Gherlone EF. A randomized prospective multicenter trial evaluating the platform-switching technique for the prevention of postrestorative crestal bone loss. Int J Oral Maxillofac Implants. 2009 Mar-Apr;24(2):299-308. PMID: 19492646.
 Atieh MA, Ibrahim HM, Atieh AH. Platform switching for marginal bone preservation around dental implants: a systematic review and meta-analysis. J Periodontol. 2010 Oct;81(10):1350-66. doi: 10.1902/jop.2010.100232. PMID: 20575657.
 Linkevicius T, Apse P, Grybauskas S, Puisys A. The influence of soft tissue thickness on crestal bone changes around implants: a 1-year prospective controlled clinical trial. Int J Oral Maxillofac Implants. 2009 Jul-Aug;24(4):712-9. PMID: 19885413.
 Linkevicius T, Apse P, Grybauskas S, Puisys A. Influence of thin mucosal tissues on crestal bone stability around implants with platform switching: a 1-year pilot study. J Oral Maxillofac Surg. 2010 Sep;68(9):2272-7. doi: 10.1016/j.joms.2009.08.018. PMID: 20605308.
 Linkevicius T, Puisys A, Steigmann M, Vindasiute E, Linkeviciene L. Influence of Vertical Soft Tissue Thickness on Crestal Bone Changes Around Implants with Platform Switching: A Comparative Clinical Study. Clin Implant Dent Relat Res. 2015 Dec;17(6):1228-36. doi: 10.1111/cid.12222. Epub 2014 Mar 28. PMID: 24673875.
 Hsu YT, Lin GH, Wang HL. Effects of Platform-Switching on Peri-implant Soft and Hard Tissue Outcomes: A Systematic Review and Meta-analysis. Int J Oral Maxillofac Implants. 2017 Jan/Feb;32(1):e9-e24. doi: 10.11607/jomi.5140. PMID: 28095526.
 Abrahamsson I, Berglundh T, Wennström J, Lindhe J. The peri-implant hard and soft tissues at different implant systems. A comparative study in the dog. Clin Oral Implants Res. 1996 Sep;7(3):212-9. doi: 10.1034/j.1600-0501.1996.070303.x. PMID: 9151585.
 Ericsson I, Nilner K, Klinge B, Glantz PO. Radiographical and histological characteristics of submerged and nonsubmerged titanium implants. An experimental study in the Labrador dog. Clin Oral Implants Res. 1996 Mar;7(1):20-6. doi: 10.1034/j.1600-0501.1996.070103.x. PMID: 9002819.
 Cochran DL, Hermann JS, Schenk RK, Higginbottom FL, Buser D. Biologic width around titanium implants. A histometric analysis of the implanto-gingival junction around unloaded and loaded nonsubmerged implants in the canine mandible. J Periodontol. 1997 Feb;68(2):186-98. doi: 10.1902/jop.1918.104.22.168. PMID: 9058338.
 Hermann JS, Buser D, Schenk RK, Cochran DL. Crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged and submerged implants in the canine mandible. J Periodontol. 2000 Sep;71(9):1412-24. doi: 10.1902/jop.2000.71.9.1412. PMID: 11022770.
 Siar CH, Toh CG, Romanos G, Swaminathan D, Ong AH, Yaacob H, Nentwig GH. Peri-implant soft tissue integration of immediately loaded implants in the posterior macaque mandible: a histomorphometric study. J Periodontol. 2003 May;74(5):571-8. doi: 10.1902/jop.2003.74.5.571. PMID: 12816287.
 Glauser R, Zembic A, Hämmerle CH. A systematic review of marginal soft tissue at implants subjected to immediate loading or immediate restoration. Clin Oral Implants Res. 2006 Oct;17 Suppl 2:82-92. doi: 10.1111/j.1600-0501.2006.01355.x. PMID: 16968384.
 Abrahamsson I, Berglundh T, Sekino S, Lindhe J. Tissue reactions to abutment shift: an experimental study in dogs. Clin Implant Dent Relat Res. 2003;5(2):82-8. doi: 10.1111/j.1708-8208.2003.tb00188.x. PMID: 14536042.
 Degidi M, Nardi D, Piattelli A. One abutment at one time: non-removal of an immediate abutment and its effect on bone healing around subcrestal tapered implants. Clin Oral Implants Res. 2011 Nov;22(11):1303-7. doi: 10.1111/j.1600-0501.2010.02111.x. Epub 2011 Feb 24. PMID: 21985288.
 Grandi T, Guazzi P, Samarani R, Garuti G. Immediate positioning of definitive abutments versus repeated abutment replacements in immediately loaded implants: effects on bone healing at the 1-year follow-up of a multicentre randomised controlled trial. Eur J Oral Implantol. 2012 Spring;5(1):9-16. PMID: 22518376.
 Koutouzis T, Gholami F, Reynolds J, Lundgren T, Kotsakis GA. Abutment Disconnection/Reconnection Affects Peri-implant Marginal Bone Levels: A Meta-Analysis. Int J Oral Maxillofac Implants. 2017 May/June;32(3):575–581. doi: 10.11607/jomi.5367. Epub 2017 Mar 23. PMID: 28334059.
 Bressan E, Grusovin MG, D'Avenia F, Neumann K, Sbricoli L, Luongo G, Esposito M. The influence of repeated abutment changes on peri-implant tissue stability: 3-year post-loading results from a multicentre randomised controlled trial. Eur J Oral Implantol. 2017;10(4):373-390. PMID: 29234745.
 Tallarico M, Caneva M, Meloni SM, Xhanari E, Covani U, Canullo L. Definitive Abutments Placed at Implant Insertion and Never Removed: Is It an Effective Approach? A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Oral Maxillofac Surg. 2018 Feb;76(2):316-324. doi: 10.1016/j.joms.2017.08.025. Epub 2017 Aug 24. PMID: 28923270.
 Abrahamsson I, Berglundh T, Glantz PO, Lindhe J. The mucosal attachment at different abutments. An experimental study in dogs. J Clin Periodontol. 1998 Sep;25(9):721-7. doi: 10.1111/j.1600-051x.1998.tb02513.x. PMID: 9763327.
 Kohal RJ, Weng D, Bächle M, Strub JR. Loaded custom-made zirconia and titanium implants show similar osseointegration: an animal experiment. J Periodontol. 2004 Sep;75(9):1262-8. doi: 10.1902/jop.2004.75.9.1262. PMID: 15515343.
 Jung RE, Sailer I, Hämmerle CH, Attin T, Schmidlin P. In vitro color changes of soft tissues caused by restorative materials. Int J Periodontics Restorative Dent. 2007 Jun;27(3):251-7. PMID: 17694948.
 Scarano A, Piattelli M, Caputi S, Favero GA, Piattelli A. Bacterial adhesion on commercially pure titanium and zirconium oxide disks: an in vivo human study. J Periodontol. 2004 Feb;75(2):292-6. doi: 10.1902/jop.2004.75.2.292. PMID: 15068118.
 Degidi M, Artese L, Scarano A, Perrotti V, Gehrke P, Piattelli A. Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in peri-implant soft tissues around titanium and zirconium oxide healing caps. J Periodontol. 2006 Jan;77(1):73-80. doi: 10.1902/jop.2006.77.1.73. PMID: 16579706.
 Nothdurft FP, Fontana D, Ruppenthal S, May A, Aktas C, Mehraein Y, Lipp P, Kaestner L. Differential Behavior of Fibroblasts and Epithelial Cells on Structured Implant Abutment Materials: A Comparison of Materials and Surface Topographies. Clin Implant Dent Relat Res. 2015 Dec;17(6):1237-49. doi: 10.1111/cid.12253. Epub 2014 Jul 26. PMID: 25066589.
 Berglundh T, Lindhe J. Dimension of the periimplant mucosa. Biological width revisited. J Clin Periodontol. 1996 Oct;23(10):971-3. doi: 10.1111/j.1600-051x.1996.tb00520.x. PMID: 8915028.
 Vervaeke S, Dierens M, Besseler J, De Bruyn H. The influence of initial soft tissue thickness on peri-implant bone remodeling. Clin Implant Dent Relat Res. 2014 Apr;16(2):238-47. doi: 10.1111/j.1708-8208.2012.00474.x. Epub 2012 Jul 3. PMID: 22758656.
 Linkevicius T, Vaitelis J. The effect of zirconia or titanium as abutment material on soft peri-implant tissues: a systematic review and meta-analysis. Clin Oral Implants Res. 2015 Sep;26 Suppl 11:139-47. doi: 10.1111/clr.12631. Epub 2015 Jun 13. PMID: 26073346.
 Chrcanovic BR, Kisch J, Albrektsson T, Wennerberg A. Factors Influencing Early Dental Implant Failures. J Dent Res. 2016 Aug;95(9):995-1002. doi: 10.1177/0022034516646098. Epub 2016 May 4. PMID: 27146701.
 Wheelis SE, Montaño-Figueroa AG, Quevedo-Lopez M, Rodrigues DC. Effects of titanium oxide surface properties on bone-forming and soft tissue-forming cells. Clin Implant Dent Relat Res. 2018 Oct;20(5):838-847. doi: 10.1111/cid.12656. Epub 2018 Aug 15. PMID: 30110131.
 Teng F, Chen H, Xu Y, Liu Y, Ou G. Polydopamine deposition with anodic oxidation for better connective tissue attachment to transmucosal implants. J Periodontal Res. 2018 Apr;53(2):222-231. doi: 10.1111/jre.12509. Epub 2017 Oct 24. PMID: 29063626.
 Susin C, Finger Stadler A, Musskopf ML, de Sousa Rabelo M, Ramos UD, Fiorini T. Safety and efficacy of a novel, gradually anodized dental implant surface: A study in Yucatan mini pigs. Clin Implant Dent Relat Res. 2019 Mar;21 Suppl 1:44-54. doi: 10.1111/cid.12754. Epub 2019 Mar 12. PMID: 30860675.