International Journal of Oral Implantology & Clinical Research

Register      Login

VOLUME 4 , ISSUE 1 ( January-April, 2013 ) > List of Articles

ORIGINAL RESEARCH

Influence of Occlusal Forces on Stress Distribution on Preloaded Dental Implant Abutment Screws: A Finite Element Analysis Study

CL Satish Babu, P Rohit, RH Deepa, KR Jnandev, Mohammed Fayaz Pasha

Citation Information : Babu CS, Rohit P, Deepa R, Jnandev K, Pasha MF. Influence of Occlusal Forces on Stress Distribution on Preloaded Dental Implant Abutment Screws: A Finite Element Analysis Study. Int J Oral Implantol Clin Res 2013; 4 (1):16-23.

DOI: 10.5005/JP-Journals-10012-1087

License: CC BY-ND 4.0

Published Online: 00-04-2013

Copyright Statement:  Copyright © 2013; Jaypee Brothers Medical Publishers (P) Ltd.


Abstract

Purpose: The aim of the study is to determine stress distribution on preloaded implant-abutment screws in three different implant systems under simulated occlusal loads. Materials and methods: Three abutments to implant internal hex joint systems were simulated by using the 3-dimensional finite element analysis; (1) Nobel Biocare replace tapered (2) Uniti (3) Lifecare self-threaded tapered cement retained abutments. Thermal load and contact analysis were used to simulate preload resulting from the torque in implant screw joint assemblies. The simulated preload implants were then loaded with three static occlusal loads (10N horizontal; 35N vertical; 70N oblique) onto the crown into the implant complex. Materials and methods: Three abutments to implant internal hex joint systems were simulated by using the 3-dimensional finite element analysis; (1) Nobel Biocare replace tapered (2) Uniti (3) Lifecare self-threaded tapered cement retained abutments. Thermal load and contact analysis were used to simulate preload resulting from the torque in implant screw joint assemblies. The simulated preload implants were then loaded with three static occlusal loads (10N horizontal; 35N vertical; 70N oblique) onto the crown into the implant complex. Results: Under preload and static occlusal forces, maximum Von-Mises stresses were concentrated at the lower portion of abutment for all systems. Maximum stresses were concentrated at lower threaded portion of abutment screw in Nobel Biocare, Uniti but in Lifecare system, stresses were concentrated at the middle threaded portion. Maximum stresses were concentrated at middle threaded portion of implant in Nobel Biocare, Uniti but at the upper threaded portion in Lifecare. Stresses increased under static occlusal forces in abutment screw in Nobel Biocare and Uniti but were more under oblique forces. In Lifecare stresses decreased under horizontal forces and increased in vertical and oblique forces. Conclusion: Although, an increase or decrease was demonstrated for the maximum calculated stress values in preloaded screws. After occlusal loads, these maximum stress values were well below the yield stress of abutment screw systems tested.


PDF Share
  1. Sertgöz A. Finite element analysis study of the effect of superstructure material on stress distribution in an implantsupported fixed prosthesis. Int J Prosthodont 1997;10(1):19-27.
  2. Zarb GA, Schmitt A. The longitudinal clinical effectiveness of osseointegrated dental implants: The Toronto study. Part III: Problems and complications encountered. J Prosthet Dent 1990; 64:185-94.
  3. Versluis A, Korioth TWP, Cardoso AC. Numerical analysis of a dental implant system preloaded with a washer. Int J Oral Maxillofac Implants 1999;14:337-41.
  4. Naert I, Quirynen MD, van Steenberghe D, Darius P. A 6-year prosthodontic study of 509 consecutively inserted implants for the treatment of partial edentulism. J Prosthet Dent 1992;67;236- 45.
  5. Breeding LC, Dixon DL, Nelson EW, Tietge JD. Torque required to loosen single-tooth implant abutment screws before and after simulated function. Int J Prosthodont 1993;6(5): 435-39.
  6. Burguete RL, Johns RB, Sabb LDSRC, King T, Patterson EA. Tightening characteristics for screwed joints in osseointegrated dental implants. J Prosthet Dent 1994;71:592-99.
  7. Haas R, Mensdorff-Pouilly N, Mailath G. Branemark single tooth implants: A preliminary report of 76 implants. J Prosthet Dent 1995;73:274-79.
  8. Becker W, Becker BE. Replacement of maxillary and mandibular molars with single endosseous implant restorations: A retrospective study. J Prosthet Dent 1995;74:51-55.
  9. Dixon DL, Breeding LC, Sadler JP, McKay ML. Comparison of screw loosening, rotation and deflection among three implant designs. J Prosthet Dent 1995;74:270-78.
  10. Weinberg LA, Kruger B. A comparison of implant/prosthesis loading with four clinical variables. Int J Prosthodont 1995 Sep-Oct;8(5):421-33.
  11. Wiskott HW, Nicholls JI, Belser UC. Stress fatigue: Basic principles and prosthodontic implications. Int J Prosthodont 1995 Mar-Apr;8(2):105-16.
  12. Cavazos E, Bell FA. Preventing loosening of implant abutment screw. J Prosthet Dent 1996;75:566-69.
  13. Binon PP, McHugh MJ. The effect of eliminating implant/ abutment rotational misfit on screw joint stability. Int J Prosthodont 1996;9(6):511-19.
  14. Papavasiliou G, Kamposiora P, Bayne SC, Felton DA. Threedimensional finite element analysis of stress-distribution around single tooth implants as a function of bony support, prosthesis type, and loading during function. J Prosthet Dent 1996;76:633-40.
  15. Schulte JK, Coffey J. Comparison of screw retention of nine abutment system: A Pilot Study. Implant Dent 1997; 6:28-27.
  16. Mollersten L, Lockowandt P, Linden LA. Comparison of strength and failure mode of seven implant systems: An in vitro test. J Prosthet Dent 1997;78:582-91.
  17. Sertgöz A. Finite element analysis study of the effect of superstructure material on stress distribution in an implantsupported fixed prosthesis. Int J Prosthodont 1997;10(1):19-27.
  18. McGlumphy EA, Mendel DA, Holloway JA. Implant screw mechanics. Dent Clin North Am 1998 Jan;42(1):71-89.
  19. Binon PP. Evaluation of the effectiveness of a technique to prevent screw loosening. J Prosthet Dent 1998;79:430-32.
  20. Fugazzotto PA, Kirsch A, Ackermann KL, Neuendorff G. Implant/Tooth-connected restorations utilizing screw-fixed attachments: A survey of 3,096 sites in function for 3 to 14 years. Int J Oral Maxillofac Implants 1999;14:819-23.
  21. Ormaechea MB, Millstein P, Hirayama H. Tube angulation effect on radiographic analysis of the implant-abutment interface. Int J Oral Maxillofacial Implants 1999;14:77-85.
  22. Faulkner MG, Wolfaardt JF, Chan A. Measuring abutment/ implant joint integrity with the periotest instrument. Int J Oral Maxillofac Implants 1999;14:681-88.
  23. Andersson M, Oden A. A new all-ceramic crown. A densesintered, high-purity alumina coping with porcelain. Acta Odontol Scand 1993;51:59-64.
  24. Haraldson T, Carlsson GE, Ingervall B. Functional state, bite force and postural muscle activity in patients with osseointegrated oral implant bridges. Acta Odontol Scand 1979;37:195-206.
  25. Kiliaridis S, Kjellberg H, Wenneberg B, Engstrom C. The relationship between maximal bite force, bite force endurance, and facial morphology during growth. A cross-sectional study. Acta Odontol Scand 1993;51:323-31.
  26. Butz F, Heydecke G, Okutan M, Strub JR. Survival rate, fracture strength and failure mode of ceramic implant abutments after chewing simulation. J Oral Rehabil 2005;32:838-43.
  27. Andersson B, Glauser R, Maglione M, Taylor A. Ceramic implant abutments for short-span FPDs: A prospective 5-year multicenter study. Int J Prosthodont 2003;16:640-46.
  28. Andersson B, Taylor A, Lang BR, Scheller H, Schaerer P, Sorensen JA, Tarnow D. Alumina ceramic implant abutments used for single-tooth replacement: A prospective 1- to 3-year multicenter study. Int J Prosthodont 2001;14:432-38.
  29. Henriksson K, Jemt T. Evaluation of custom-made procera ceramic abutments for single-implant tooth replacement: A prospective 1-year follow-up study. Int J Prosthodont 2003; 16:626-30.
  30. Glauser R, Wohlwend A, Studer S. Application of zirconia abutments on single-tooth implants in the maxillary esthetic zone. A 6-year clinical and radiographic follow-up report. Applied Osseointegration Research 2004;4:41-45.
  31. Heydecke G, Sierraalta M, Razzoog ME. Evolution and use of aluminum oxide single-tooth implant abutments: A short review and presentation of two cases. Int J Prosthodont 2002;15: 488-93.
  32. Ottl P, Piwowarczyk A, Lauer HC, Hegenbarth EA. The Procera AllCeram system. Int J Periodontics Restorative Dent 2000; 20:151-61.
  33. Pröbster L. All-ceramic crowns on modified CeraOne abutments: A case report. Quintessence Int 1998;29:52-65.
  34. Yildirim M, Fischer H, Marx R, Edelhoff D. In vivo fracture resistance of implant-supported all-ceramic restorations. J Prosthet Dent 2003;90:325-31.
  35. Att W, Kurun S, Gerds T, Strub JR. Fracture resistance of singletooth implant-supported all-ceramic restorations after exposure to the artificial mouth. J Oral Rehabil 2006;33:380-86.
  36. Att W, Kurun S, Gerds T, Strub JR. Fracture resistance of singletooth implant-supported all-ceramic restorations: An in vitro study. J Prosthet Dent 2006;95:111-16.
  37. 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;75: 292-96.
  38. Rimondini L, Cerroni L, Carrassi A, Torricelli P. Bacterial colonization of zirconia ceramic surfaces: An in vitro and in vivo study. Int J Oral Maxillofac Implants 2002;17:793-98.
  39. Kou W, Molin M, Sjogren G. Surface roughness of five different dental ceramic core materials after grinding and polishing. J Oral Rehabil 2006;33:117-24.
  40. Raigrodski AJ. Contemporary all-ceramic fixed partial dentures: a review. Dent Clin North Am 2004;48:531-44.
  41. Guazzato M, Albakry M, Ringer SP, Swain MV. Strength, fracture toughness and microstructure of a selection of all ceramic materials. Part II. Zirconia-based dental ceramics. Dent Mater 2004;20:449-56.
  42. Studart AR, Filser F, Kocher P, Luthy H, Gauckler LJ. Cyclic fatigue in water of veneer-framework composites for all-ceramic dental bridges. Dent Mater 2007;23:177-85.
  43. Vigolo P, Fonzi F, Majzoub Z, Cordioli G. An in vitro evaluation of ZiReal abutments with hexagonal connection: In original state and following abutment preparation. Int J Oral Maxillofac Implants 2005;20:108-14.
  44. Vigolo P, Fonzi F, Majzoub Z, Cordioli G. An in vitro evaluation of titanium, zirconia, and alumina procera abutments with hexagonal connection. Int J Oral Maxillofac Implants 2006;21:575-80.
  45. Park SW, Driscoll CF, Romberg EE, Siegel S, Thompson G. Ceramic implant abutments: Cutting efficiency and resultant surface finish by diamond rotary cutting instruments. J Prosthet Dent 2006;95:444-49.
  46. Kim YK, Yun PY, Lee HJ, Ahn JY, Kim SG. Ridge preservation of the molar extraction socket using collagen sponge and xenogenic bone grafts. Implant Dent Aug 2011;20(4):267-72.
  47. Len Tolstunov, Jibin Chi. Alveolar ridge augmentation: comparison of two socket graft materials in implant cases. Compend Cont Edu, March 2011;32(2).
  48. Brunski JB. Forces on dental implants and interfacial stress transfer. In: Laney WR, Tolman DE (Eds). Tissue Integration in Oral, Orthopaedic and Maxillofacial Reconstruction. Chicago: Quintessence 1992:108-24.
  49. Brunski JB. Avoiding pitfalls in overloading and micromotions of intraosseous implants (Interview). Dent Implantol Update 1993;4(10):77-81.
  50. Tarnow D, Elian N, Fletcher P, et al. Vertical distance from the crest of bone to the height of the interproximal papilla between adjacent implants. J Periodontol 2003;74:1785-88.
  51. Ericsson J, Persson LG. Different types of implant-associated reactions in periodontal soft tissues. J Clin Periodont 1995; 22:255-61.
  52. Steinebrunner L, Wolfart S. In vitro evaluation of bacterial leakage along the implant of different implant abutment interface of different implant systems. Int J Oral Maxillofac Implants 2005;20:875-81.
  53. Engelke W, Decco OA. In vitro evaluation of horizontal implant micromovement in bone specimen with contact endoscopy. Implant Dent 2004;13:88-94.
  54. Hermann J, Buser D, Schenk RK, Schoolfield JD. Influence of the size of the microgap on crestal bone changes around titanium implants: A histometric evaluation of unloaded non-submerged implants in canine mandible. J Periodontol 2001;72:1372-83.
  55. Hermann JS, Buser D, Schenk RK, et al. Crestal bone changes around titanium implants: A histometric evaluation of unloaded non-submerged and submerged implants in the canine mandible. J Peridontol 2000;71:1412-24.
  56. Wohrle PS. Nobel perfect esthetic scalloped implant: Rationale for a new design. Clin Implant Dent Relat Res 2003;5:64-73.
  57. Nentwig GH. Ankylos implant system: Concept and clinical application. J Oral Implantol 2004;30:171-77.
  58. Gardener D. Maintaining crestal bone around dental implants: Literature review and clinical technique. Dentistry Today 2006.
  59. Tonetti MS, Sanz M. Consensus report of session B. In: Lang N, Karring T, Lindhe J. Proceedings of the 3rd European Workshop on Periodontology and Implant Dentistry. Berlin: Quintessence 1999:185-88.
  60. Huang MT, Ho CT, Wang ZY, Ferraro T, Lou YR, Stauber K, Ma W, Georgiadis C, Laskin JD, Conney AH. Inhibition of skin tumorigenesis by rosemary and its constituents carnosol and ursolic acid. Cancer Res. 1994 Feb;54(3):701-708.
  61. Bernardes WA, Lucarini R, Tozatti MG, Souza MG, Silva ML, Filho AA, Martins CH, Crotti AE, Pauletti PM, Groppo M, et al. Antimicrobial activity of tosmarinus officinalis against oral pathogens: relevance of carnosic acid and carnosol. Chem Biodivers 2010 Jul;7(7):1835-1840.
  62. Parolia A, Thomas MS, Kundabala M, Mohan M. Propolis and its potential uses in oral health. Int J Med Sci 2010 Jul;2(7): 210-215.
  63. Oncag O, Cogulu D, Uzel A, Sorkun K. Efficacy of propolis as an intracanal medicament against Enerococcus faecalis. Gen Dent 2006 Sep-Oct:54(5):319-322.
  64. Martin MP, Pileggi R. A quantitative analysis of propolis: a promising new storage media following avulsion. Dent Traumatol 2004 Apr:20(2):85-89.
  65. Carbajal D, Casaco A, Arruzazabala L, Gonzalez R, Tolon Z. Pharmacological study of Cymbopogon citratus leaves. J Ethnopharmacol 1989 Feb;25(1):103-107.
  66. Sanches NR, Cortez DAG, Schiavini MS, Nakamura CV, Filho BPD. An evaluation of antibacterial activities of Psidium guajava. Braz Arch Biol Technol 2005 May;48(3):4229-4230.
  67. Sanda KA, Grema HA, Geidam YA, Bukar-Kolo YM. Pharmacological aspects of Psidium guajava: an update. Int J Pharmacol 2011 May;7:316-324.
  68. Menezes SM, Cordeiro LN, Viana GS. Punica grantum (pomegranate) extract is active against dental plaque. J Herb Pharmacother 2006;6(2):79-92.
  69. Vasconcelos LC, Sampaio FC, Sampaio MC, Pereira Mdo S, Higino JS, Peixoto MH. Minimum inhibitory concentration of adherence of punica granatum linn (pomegranate) gel against S. mutans, S. mitis and C albicans. Braz Dent J 2006;17(3): 223-227.
  70. Prasad D, Kunnaiah R. Punica granatum: a review on its potential role in treating periodontal disease. J Indian Soc Periodontol 2014 Jul;18(4):428-432.
  71. Sauvaire Y, Petit P, Baissac Y, Ribes G. Chemistry and pharmacology of fenugreek. In: Herbs, botanicals and teas. Mazza G, Oomah BD, editors. Lancaster, Pennsylvania: Technomic Pub. Co; 2000. p. 107-129.
  72. Acharya SN, Basu SK, Thomas JE. Methods for the improvement of plant medicinal properties with particular reference to fenugreek (Trigonella foenum-graecum L.). In: Acharya SN, Thomas JE, editors. Advances in medicinal plant research. Kerala, India: Research Signpost; 2007b p. 491-412.
  73. Al-Habori M, Raman A. Pharmacological properties in fenugreek. - In: Petropoulos GA, editor. The genus trigonella. 1st ed. London and New York: Taylor and Francis 2002. p. 163-182.
  74. Saini P, Al-Shibani N, Sun J, Zhang W, Song F, Gregson KS, Windsor LJ. Effects of calendula officinalis on human gingival fibroblasts. Homeopathy 2012 Apr;101(2):92-98.
  75. Khairnar MS, Pawar B, Marawar PPA. Evaluation of calendula officinalis as an anti-plaque and anti-gingivitis agent. J Indian Soc Periodontol 2013 Nov-Dec;17(6):741-747.
  76. Chakraborthy GS. Antimicrobial activity of leaf extract of calendula officinalis Linn. J Herb Med Toxicol 2008 Jun;2(2):65–66.
  77. Zilda CG, Claudia MR, Sandra RF. Antifungal activity of the essential oil from calendula officinalis L growing in Brazil. Braz J Microbiol 2008;39(1):61-63.
  78. Bussadori SK, Castro LC, Galvão AC. Papain gel: a new chemo-mechanical caries removal agent. J Clin Pediatr Dent 2005 Winter;30(2):115-119.
  79. Bertassoni LE, Marshall GW. Papain-gel degrades intact nonmineralized type I collagen fibrils. Scanning 2009 Nov- Dec;31(6):253-258.
  80. Moon SE, Kim HY, Cha JD. Synergistic effect between clove oil and its major compounds and antibiotics against oral bacteria. Arch Oral Biol 2011 Sep;56(9):907-916.
  81. Pinto E, Vale-Silva L, Cavaleiro C, Salgueiro L. Antifungal activity of the clove essential oil from Syzygium aromaticumon, candida, aspergillus and dermatophyte species. J Med Microbiol 2009 Nov;58(Pt 11):1454-1462.
  82. Olajide OA, Makinde JM, Awe SO. Evaluation of the pharmacological properties of nutmeg oil in rats and mice. Pharma Biol 2000;38(5):385-390.
  83. Thanoon SZ, Al-Refai AS, Kamal A. Antibacterial effect and healing potential of nutmeg oil for chemically induced oral ulcerations in rabbits. Zanco J Med Sci 2013;17(2): 393-399.
  84. Mitwally MF, Casper RF. Use of an aromatase inhibitor for induction of ovulation in patients with an inadequate response to clomiphene citrate. Fertil Steril 2001;75:305-09.
  85. Sammour A, Bijan MM, Tan SL, Tulandi T. Prospective randomised trial comparing the effects of letrazole (LE) and clomiphene citrate (CC) on follicular development, endometrial thickness and pregnancy rate in patients undergoing superovulation prior to intrauterine insemination (IUI). Fertil Steril 2001;76(Suppl 1):S110.
  86. Mitwally MF, Casper RF. Single-dose administration of an aromatase inhibitor for ovarian stimulation. Fertil Steril 2005;83:229-31.
  87. Fisher SA, Reid RL, Van Vugt DA, Casper RF. A randomized double-blind comparison of the effects of clomiphene citrate and the aromatase inhibitor letrozole on ovulatory function in normal women. Fertil Steril 2002;78:280-85.
  88. Fatemi HM, Kalibianakis E, Tournaye H, Camus M, Van Steirteghem AC, Devroey P. Clomiphene citrate vs letrozole for ovarian stimulation: A pilot study. Reprod Biomed Online 2003;7:543-46.
  89. Hu Y, Cortvrindt R, Smitz J. Effects of aromatase inhibition on in vitro follicle and oocyte development analyzed by early preantral mouse follicle culture. Mol Reprod Dev 2002;61: 549-59.
  90. Shetty G, Krishnamurthy H, Krishnamurthy HN, Bhatnagar S, Moudgal NR. Effect of estrogen deprivation on the reproductive physiology of male and female primates. J Steroid Biochem Mol Biol 1997;61:157-66.
  91. Mitwally MF, Casper RF. Aromatase inhibition reduces gonadotrophin dose required for controlled ovarian stimulation in women with unexplained infertility. Hum Reprod 2003;18:1588-97.
  92. Mitwally MF, Casper RF. Aromatase inhibition improves ovarian response to follicle-stimulating hormone in poor responders. Fertil Steril 2002;77:776-80.
  93. Goswami SK, Das T, Chattopadhyay R, Sawhney V, Kumar J, Chaudhury K, Chakravarty BN, Kabir SN. A randomized single blind controlled trial of letrozole as a low-cost IVF protocol in women with poor ovarian response: A preliminary report. Hum Reprod 2004;19:2031-35.
  94. Newkirk KM, Chandler HL, Parent AE, et al. Ultraviolet radiation-induced corneal degeneration in 129 mice. Toxicol Pathol 2007;35:819-26.
  95. Pettenati MJ, Sweatt AJ, Lantz P, et al. The human cornea has a high incidence of acquired chromosome abnormalities. Hum Genet 1997;101:26-29.
  96. Snibson GR. Collagen cross-linking: A new treatment paradigm in corneal disease—a review. Clin Experiment Ophthalmol 2010;38:141-53.
  97. Spoerl E, Raiskup-Wolf F, Kuhlisch E, Pillunat LE. Cigarette smoking is negatively associated with keratoconus. J Refract Surg 2008;24:S737-40.
  98. Rabinowitz YS, Nesburn AB, McDonnell PJ. Videokeratography of the fellow eye in unilateral keratoconus. Ophthalmology 1993;100:181-86.
  99. Goodrich DW, Lee WH. The molecular genetics of retinoblastoma. Cancer Surv 1990;9:529-54.
  100. Moodaley LC, Woodward EG, Liu CS, Buckley RJ. Life expectancy in keratoconus. Br J Ophthalmol 1992;76:590-91.
  101. Honein MA, Dawson AL, Petersen EE, Jones AM, Lee EH, Yazdy MM, Ahmad N, Macdonald J, Evert N, Bingham A, et al. Birth defects among fetuses and infants of US women with evidence of possible Zika virus infection during pregnancy. JAMA 2017 Jan 3;317(1):59-68.
  102. Chervenak FA, Jeanty P, Cantraine F, Chitkara U, Venus I, Berkowitz RL, Hobbins JC. The diagnosis of fetal microcephaly. Am J Obstet Gynecol 1984 Jul 1;149(5):512-517.
  103. Papageorghiou AT, Thilaganathan B, Bilardo CM, Ngu A, Malinger G, Herrera M, Salomon LJ, Riley LE, Copel JA. ISUOG Interim Guidance on ultrasound for Zika virus infection in pregnancy: information for healthcare professionals. Ultrasound Obstet Gynecol 2016 Apr;47(4):530-532.
  104. Chibueze EC, Parsons AJ, Lopes KD, Yo T, Swa T, Nagata C, Horita N, Morisaki N, Balogun OO, Dagvadorj A, et al. Diagnostic accuracy of ultrasound scanning for prenatal microcephaly in the context of Zika virus infection: a systematic review and meta-analysis. Sci Rep 2017 May 23;7(1):2310.
  105. Cordeiro MT. Zika virus: laboratory diagnosis. In: Zika in focus. Springer International Publishing; 2017. pp. 59-62.
  106. Mlakar J, Korva M, Tul N, Popović M, Poljšak-Prijatelj M, Mraz J, Kolenc M, Resman Rus K, Vesnaver Vipotnik T, Fabjan Vodušek V, et al. Zika virus associated with microcephaly. N Engl J Med 2016 Mar 10;374(10):951-958.
  107. Zare Mehrjardi M, Keshavarz E, Poretti A, Hazin AN. Neuroimaging findings of Zika virus infection: a review article. Jpn J Radiol 2016 Dec;34(12):765-770.
  108. Oliveira Melo AS, Malinger G, Ximenes R, Szejnfeld PO, Alves Sampaio S, Bispo de Filippis AM. Zika virus intrauterine infection causes fetal brain abnormality and microcephaly: tip of the iceberg? Ultrasound Obstet Gynecol 2016 Jan;47(1):6-7.
  109. Araujo AQ, Silva MT, Araujo AP. Zika virus-associated neurological disorders: a review. Brain 2016;139(8):2122-2130.
  110. Brasil P, Pereira JP Jr, Moreira ME, Ribeiro Nogueira RM, Damasceno L, Wakimoto M, Rabello RS, Valderramos SG, Halai UA, Salles TS, et al. Zika virus infection in pregnant women in Rio de Janeiro. N Engl J Med 2016 Dec 15;375(24):2321-2334.
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.