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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 13  |  Issue : 5  |  Page : 633-636  

Stress distribution in cortical bone around the basal implant – A finite element analysis


1 Department of Prosthodontics, Institute of Dental Sciences, Baeilly, Uttar Pradesh, India
2 Department of Oral and Maxillofacial Surgery, School of Dental Sciences, Krishna Institute of Medical Sciences Deemed to be University, Karad, Maharashtra, India
3 Department of Prosthodontics, Purvanchal Institute of Dental Sciences, Gorakhpur, Uttar Pradesh, India
4 Department of Periodontics and Oral Implantology, Kalinga Institute of Dental Sciences, KIIT Deemed to be University, Bhubaneswar, Odisha, India
5 Consultant Prosthodontist, Katihar, Bihar, India

Date of Submission15-Oct-2020
Date of Decision17-Nov-2020
Date of Acceptance18-Nov-2020
Date of Web Publication05-Jun-2021

Correspondence Address:
Anip Kumar Roy
Department of Prosthodontics, Institute of Dental Sciences, Bareilly, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jpbs.JPBS_679_20

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   Abstract 


Aim: The aim of the study was to develop a model that represents a basal implant with stress distribution in the cortical bone on application of loads emulating masticatory forces. Materials and Methods: In this study, the stress distribution in the bone and the implant is evaluated by applying various loads that emulate the masticatory forces. The geometric models of cortical bone representing the premolar area and a basal implant model of the following specifications, longitudinal oval threaded pin (1.95 mm × 2.1/2.3 mm ø), height of the implant head (7.2 mm), and width of the implant head (3.5 mm) (BOI BS, IDHEDENTAL), were generated with Ansys software, and both the implant model and the bone model are superimposed to mimic the bone implant system as a unit. Results: Overall comparison of stress distribution on both implant shaft and implant neck showed that maximum stresses are located at implant neck irrespective of forces applied and minimum stresses are located at implant shaft. On overall comparison of stresses seen within the bone and the implant, it was observed that the maximum stresses were seen in the implant neck followed by the implant shaft followed by the bone interface. Conclusion: The present study concluded that the stress transmission is greatest during application of oblique load (70 N) followed by horizontal load (10 N) and the least by vertical load (35 N).

Keywords: Basal implant, cortical bone, finite element analysis, stress


How to cite this article:
Roy AK, Dixit N, Punde P, Sinha KT, Jalaluddin M, Kumar A. Stress distribution in cortical bone around the basal implant – A finite element analysis. J Pharm Bioall Sci 2021;13, Suppl S1:633-6

How to cite this URL:
Roy AK, Dixit N, Punde P, Sinha KT, Jalaluddin M, Kumar A. Stress distribution in cortical bone around the basal implant – A finite element analysis. J Pharm Bioall Sci [serial online] 2021 [cited 2021 Sep 17];13, Suppl S1:633-6. Available from: https://www.jpbsonline.org/text.asp?2021/13/5/633/317619




   Introduction Top


The ideal objective of present-day dentistry is to reestablish the patient to typical shape, work, comfort, feel, discourse, and health.[1] Although the study of rebuilding of missing teeth is as old as 300 BC with the Egyptians utilizing an assortment of techniques to make sure about the prosthetic teeth, the effective substitution of lost normal teeth by dental implant is a meaningful step forward in dentistry.[2] What makes the implant dentistry interesting is the capacity to accomplish this objective paying little heed to the decay, ailment, or injury of the stomatognathic framework.

Success or failure of dental implants relies upon different complex intertwined factors, for example, bone amount, bone quality, careful strategies, implant configuration, implant surface and host-related variables, and so on for the osseointegration of endosseous implant to happen, not just a sufficient bone amount (stature, width, shape) is required, yet in addition a satisfactory bone thickness is required. Zarb and Schmitt expressed that the bone structure is the most significant factor in choosing the most good treatment choice in implant dentistry.[3]

Sort of implant picked to supplant the missing tooth is a significant target in biomechanical advancement of dental implant. Crestal and basal implants are endosseous helps to make osseointegrated purposes of maintenance for fixed and removable false teeth. These two sorts of implant are not just separated by the manner in which they are inserted yet additionally by the manner in which the powers are sent. As per the notable implantological rules for dental rebuilding efforts, the crestal implants are demonstrated in circumstances when a sufficient vertical bone gracefully is given.[4]

The finite element method (FEM) is a mathematical strategy for examination for stresses and misshappenings in structures of some random calculation. The structure is discretized into the alleged “finite elements” associated through nodes. The sort, course of action, and complete number of components influence the precision of the results.[5] Literature on the stress distribution in the underlying bone while using basal implants is limited. Hence, the purpose of this study was to develop a model that represents a basal implant and study the stress distribution in the cortical bone on application of loads emulating masticatory forces.


   Materials and Methods Top


This in vitro study was carried out at “Tejvi Techno Solutions” in Bangalore using the following computer characteristics.

  • Ansys 14.5 version
  • System: Pentium IV
  • Memory: 512 GB
  • Ram: 256 MB.


The study was divided under the following steps:

Construction of geometric model

Modeling of bone

The calculation in this examination is to produce finite element models from computerized tomography scan (CT scan) information, which depended on Cruz et al.[6] study, wherein a CT output of human mandible was taken and each segment from center to mental foramen was extended on a graph paper. The thickness of bone was taken as D2 as it is most regular bone thickness saw in the mandible.[1] The form information of the profiles was changed into the x, y, and z co-ordinate points and read by finite element program associating these arrange points gave line math likewise called as wire outline displaying. Interfacing the lines of each part gave surface calculation likewise called surface modeling. Three-dimensional volumes were made from associated progressive profiles to define the final solid geometry of cortical bone. Through this cycle, the CT check information was changed over into three-dimensional strong model of the first premolar area of edentulous mandible.

Modeling of implant

A commercially pure Grade 2 titanium, One-piece basal implants with longitudinal oval threaded pin (1.95 mm × 2.1/2.3 mm ø), height of the implant head is 7.2 mm, width of the implant head is 3.5 mm(BOI BS,IDHEDENTAL), was used in this study. Implant model was manually drawn from precise geometric measurements acquired from the manufactures; now, both the implant and bone models are superimposed simulating the implant placement into bone.

Preparing of finite element mesh

The three-dimensional finite element model relating to the geometric model was produced utilizing Ansys 14.5 Pre-Processor. Care was taken during lattice to move components in the locale of most prominent enthusiasm of stress dissemination design. Thusly, default component size with SOLID 187 component was chosen. It is a higher request three-dimensional 10-node component with quadratic uprooting conduct, which is appropriate for displaying unpredictable lattices (for example, those delivered from different CAD/CAM Systems). The component was characterized as 10 nodes having 3° of opportunity at every hub interpretation in the nodal x, y, and z headings. The components were built, so their size angle proportion would yield sensible arrangement exactness. The finished anatomical model comprised absolute various 26,280 nodes and 123,659 components.

Material properties

All the imperative tissues (cortical bone) and implant were ventured to be directly elastic, homogeneous and isotropic. Although cortical bone has anisotropy material characteristics and possesses regional stiffness variation. They were displayed isotropically because of the inaccessibility of adequate information and trouble in building up the central hub of anisotropy.

The relating versatile properties, for example, Young's modulus (E) and Poisson's ratio (μ) of cortical bone and implant, were resolved according to literature survey.

Application of boundary conditions

For the limit state of the model, a supporting framework was arrangement. Even limit conditions were forced on the distal side all the three interpretations are fixed.

Application of different loads

The magnitude and the direction of the loading forces were derived from the studies of Meijer et al.[7]

The loads applied were:

  • 35 N vertical load applied to the implant head in occlusogingival direction
  • 10 N horizontal load applied at 0° over the implant head in a labiolingual direction
  • 70 N oblique load applied at 120° to the occlusal plane on the implant head in a labiolingual direction. Simulating the load from the muscles of mastication.


Analysis of stress pattern

A vertical (35 N), horizontal (10 N), oblique (70 N) emulating masticatory forces were applied to model. The model was examined by the Processor and showed by Post Processor of Finite Element Software (Ansys Version 14.5, Canonsburg, Pennsylvania) utilizing von Mises stress analysis. Von Mises pressure esteems are characterized as the start of twisting for pliable materials, for example, metallic implants. Disappointment happens when von Mises Stress esteems surpass the yield quality of an implant material. Accordingly, they are significant for deciphering the stresses happening inside the implant material.


   Results Top


[Table 1] reveals the overall comparison of stress distribution on both implant shaft and implant neck; it is found that maximum stresses are located at implant neck irrespective of forces applied and minimum stresses are located at implant shaft.
Table 1: Comparison of stress distribution on implant neck and shaft under loading condition

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On overall comparison of stresses seen within the bone and the implant, it was observed that the maximum stresses were seen in the implant neck followed by the implant shaft followed by the bone interface. It is also observed that the stress transmission is greatest during application of oblique load (70 N) followed by horizontal load (10 N) and the least by vertical load (35 N) [Table 2].
Table 2: Overall comparison of stress distribution within the bone and within the implant

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   Discussion Top


Today, we, as prosthodontists, focus our energy toward successful planning and placement of implants. Over the years, basal implants have emerged and begun to gain importance. Crestal implants are most commonly practiced among implants. Although the crestal implants enjoy a high degree of success, their success is reduced in cases where there is inadequate bone volume; in such cases, bone augmentation is required which will add the overall cost for the dental implant treatment.

In contrast to crestal implants, basal implants require less bone volume for their success. Basal implants utilize the horizontal and cortical bone supply, rather than the bone marrow, and they allow immediate loading and functioning. Due to their cortical anchorage, the functional load is transmitted to highly mineralized, therefore, resistant and resorption stable cortical bone regions. Basal implants have a radically different approach in their insertion into the bone; they are inserted through a T-shaped slot into the jaw bone (The T-shaped slot is inverted in the mandible). The basal implants mainly consist of the shaft portion which connects the basal plate and abutment portion will help in load transmission into underlying bone.[8]

Stress distribution in crestal implants are always located at the implant neck.[7] Literature[9],[10] available to us shows sufficient amount of studies that have been conducted regarding the stress distribution around the crestal implants, but the literature about the stress distribution around basal implants is limited. The main purpose of this study was to develop a model that reflects the cortical bone and basal implant as a single unit and study the stress distribution in the cortical bone around the basal implant by applying the loads that emulate the masticatory forces.

The connection between implant design and load conveyance at the implant–bone interface is a significant issue to comprehend. Numerous elements influence load move at the bone–implant interface, for example, the sort of stacking, material properties of the implant and prosthesis, implant calculation, surface structure, implant design quality (measurement and length) and amount of encompassing bone, and nature of bone–implant interface.[11] Research shows that the issue of implant crack in the back district seems to have an expanded danger of overburden. Different elements have been proposed as being answerable for the distinctions in stacking conditions on back halfway edentulous reclamations and full-arch prostheses. Overburden initiated bone resorption appeared to go before implant break in a noteworthy number of the patients, particularly in the single-molar, single-implant situations.[12]

The success of the dental implants can be studied by pull-out tests, push-out tests, torque tests, mechanical pressure investigation, photograph flexibility, and strain estimation on bone surfaces. These procedures have certain impediments, for example, troubles in adjustments in the wake of demonstrating. So as to examine the pressure circulation in and around the implant, finite element analysis is developed as a valuable instrument. The FEM, began from aeronautic design, has been utilized for five decades for mathematical stress analysis.[13]

To suit the points of this examination, a three-dimensional finite element model was produced. This is appropriate to consider the genuine biomechanical conduct in limited areas of significant supporting hard tissues of the mandible. Certain presumptions were made in mathematical contemplations. Material properties, limit conditions, and bone–implant interface to make demonstrating and explaining measure possible.[14] It is clear that the introduced model was just an estimate of the clinical circumstance. Therefore, it is advisable to focus on qualitative comparison rather than quantitative data from these analyses.


   Conclusion Top


Within the limitations of the study, the following conclusions were drawn:

  1. Maximum von Mises stresses were found at the cortical bone and implant interface, when cortical bone alone is considered, irrespective of forces applied
  2. Maximum von Mises stresses were found at the implant neck followed by the implant shaft, when basal implant alone is considered, irrespective of forces applied
  3. Irrespective of the magnitude of forces that are applied in vertical, horizontal, or oblique directions, the order of stress transmission through the implant to the surrounding bone remains unaltered
  4. It is also observed that the stress transmission is greatest during application of oblique load (70 N) followed by horizontal load (10 N) and the least by vertical load (35 N).


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Misch CE. Contemporary Implant Dentistry. 3rd ed. United States: Elsevier Mosby; 2012. p. 3, 136, 670-1.  Back to cited text no. 1
    
2.
Steigenga JT, Al-Shammari KF, Nociti FH, Misch CE, Wang HL. Dental implant design and its relationship to long-term implant success. Implant Dent 2003;12:306-15.  Back to cited text no. 2
    
3.
Sevimay M, Turhan F, Kiliçarslan MA, Eskitascioglu G. Three-dimensional finite element analysis of the effect of different bone quality on stress distribution in an implant-supported crown. J Prosthet Dent 2005;93:227-34.  Back to cited text no. 3
    
4.
Ihde S. Comparison of basal and crestal implants and their modus of application. Smile Dent J 2009;4:36-46.  Back to cited text no. 4
    
5.
Van Staden RC, Guan H, Loo YC. Application of finite element method in dental implant research. Comput Methods Biomech Biomed Engin 2006;9:257-70.  Back to cited text no. 5
    
6.
Cruz M, Wassall T, Toledo EM, Barra LP, Lemonage AC. Three dimensional finite element stress analysis of a cuneiform-geometry implant. Int J Oral Maxillof Implants 2003;18:675-84.  Back to cited text no. 6
    
7.
Meijer HJ, Kuiper JH, Starmans FJ, Bosman F. Stress distribution around dental implants: Influence of superstructure, length of implants and height of mandible. J Prosthet Dent 1992;68:96-102.  Back to cited text no. 7
    
8.
Nair C, Bharati S, Jawade R, Jain M. Basal implants – A panacea for atrophic ridges. J Dent Sci Oral Rehabitil 2013;4:1-4.  Back to cited text no. 8
    
9.
Kong L, Liu B, Li D, Song Y, Zhang A, Dang F, et al. Comparative study of 12thread shapes of dental implant designs: A three dimensional finite elementanalysis. World J Modelingsimul 2006;2:134-40.  Back to cited text no. 9
    
10.
Eskitascioglu G, Usumez A, Sevimay M, Soykan M, Unsal E. The influenceof occlusal loading on stresses transferred to implant-supported prosthesis andsupporting bone: A three dimensional finite element study. J Prosthet Dent 2004;91:144-50.  Back to cited text no. 10
    
11.
El-Anwar MI, El-Zawahry MM. A three dimensional finite element study on dental implant design. J Gen Eng Biotechnol 2011;9:77-82.  Back to cited text no. 11
    
12.
Rangert B, Krogh PH, Langer B, van Roekel N. Bending overload and implant fracture: A retrospective clinical analysis. Int J Oral Maxillofac Implants 1995;10:326-34.  Back to cited text no. 12
    
13.
Benzing UR, Gall H, Weber H. Biomechanical aspects of two different implant-prosthetic concepts foredentulous maxillae. Int J Oral Maxillofac Implants 1995;10:188-98.  Back to cited text no. 13
    
14.
Geng JP, Tan KB, Liu GR. Application of finite element analysis in implant dentistry: A review of the literature. J Prosthet Dent 2001;85:585-98.  Back to cited text no. 14
    



 
 
    Tables

  [Table 1], [Table 2]



 

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