Journal of Indian Society of Periodontology
Journal of Indian Society of Periodontology
Home | About JISP | Search | Accepted articles | Online Early | Current Issue | Archives | Instructions | SubmissionSubscribeLogin 
Users Online: 1452  Home Print this page Email this page Small font size Default font size Increase font sizeWide layoutNarrow layoutFull screen layout


 
   Table of Contents    
ORIGINAL RESEARCH
Year : 2013  |  Volume : 17  |  Issue : 5  |  Page : 637-643  

2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla


1 Department of Periodontology and Implantology, H.K.E. Society's S. Nijalingappa Institute of Dental Sciences and Research, Gulbarga, Karnataka, India
2 Department of Periodontics, Saveetha Dental College and Hospital, Chennai, Tamil Nadu, India

Date of Submission19-Jun-2012
Date of Acceptance27-Jul-2013
Date of Web Publication4-Oct-2013

Correspondence Address:
Shrikar R Desai
Department of Periodontology and Implantology, H.K.E. Society's S. Nijalingappa Institute of Dental Sciences and Research, Sedam Road, Gulbarga - 585 105, Karnataka
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-124X.119283

Rights and Permissions
   Abstract 

Aim: The aim of the study is to evaluate the influence implant length on stress distribution at bone implant interface in single immediately loaded implants when placed in D4 bone quality. Materials and Methods: A 2-dimensional finite element models were developed to simulate two types of implant designs, standard 3.75 mm-diameter tapered body implants of 6 and 10 mm lengths. The implants were placed in D4 bone quality with a cortical bone thickness of 0.5 mm. The implant design incorporated microthreads at the crestal part and the rest of the implant body incorporated Acme threads. The Acme thread form has a 29° thread angle with a thread height half of the pitch; the apex and valley are flat. A 100 N of force was applied vertically and in the oblique direction (at an angle of 45°) to the long axis of the implants. The respective material properties were assigned. Micro-movements and stresses at the bone implant interface were evaluated. Results: The results of total deformation (micro-movement) and Von mises stress were found to be lower for tapered long implant (10 mm) than short implant (6 mm) while using both vertical as well as oblique loading. Conclusion: Short implants can be successfully placed in poor bone quality under immediate loading protocol. The novel approach of the combination of microthreads at the crestal portion and acme threads for body portion of implant fixture gave promising results.

Keywords: Finite element analysis, immediate loading, implant length, microthreads


How to cite this article:
Desai SR, Singh R, Karthikeyan I. 2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla. J Indian Soc Periodontol 2013;17:637-43

How to cite this URL:
Desai SR, Singh R, Karthikeyan I. 2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla. J Indian Soc Periodontol [serial online] 2013 [cited 2020 Apr 8];17:637-43. Available from: http://www.jisponline.com/text.asp?2013/17/5/637/119283


   Introduction Top


A dental implant serves as a load-bearing device that sustains masticatory forces and also transfers loads to peri-implant bone. [1] Initially, it was considered that the process of osseointegration requires on average an undisturbed healing of 3 months in the mandible and 6 months in the maxilla. [2],[3],[4] An increasing interest with regard to early and immediate loading of implants has been noticed, to expedite the restorative outcome. Immediately loaded dental implants have shown long-term success of removable and fixed prostheses using clinical and experimental animal trials. [5],[6],[7],[8],[9],[10]

By using finite element analysis (FEA), it has been shown that the highest risk of bone resorption occurs in the neck region of an implant. [11],[12],[13] Beginning at the crestal area of the cortical bone, bone loss, can progress toward the apical region, endangering the longevity of the implant and prosthesis. [14] In areas with low bone density, prerequisites for successful treatment include surgical procedures for adequate primary implant stability, [15],[16] prosthetic protocols with load control [17],[18] and tapered implant geometries with osseoconductive implant surfaces. [19],[20] Improvement of primary implant stability has been seen with the use of tapered implant geometry. [21]

Load transfer to implant depends on successful healing of the osteotomy and osseointegration. It is characterized as a direct structural and functional connection between the bone and the implant surface. [22],[23],[24] Thus, to improve the osseointegration of implant to bone and establish implant stability, increasing the implant surface area (increasing the implant diameter or implant length) might help. [1] Increasing the length of an implant by 3 mm increases the surface area by more than 20%. [25] The increase in the surface area might help to improve implant support, implant stability and the odds of survival. [26] However, the jaw anatomy limits the choice of implant length. The presence of the inferior alveolar nerve and mental foramen in the mandible and the maxillary sinus in the maxilla, restricts the available bone height. [27],[28],[29] In these situations, the use of short length implants is more appropriate.

Threads have been incorporated into implants to improve initial stability, [30],[31] enlarge implant surface area and distribute stress favorably. [32],[33] For a low density bone, implants should be selected on a bioengineering principle that the implant body has a thread profile, which maintains strain levels at the "steady state zone" [34] and stimulates bone preservation. The optimal load distribution that microthread offers, counteract marginal bone resorption. [35] Microthread preserves the bone better than an implant without microthread. [36] The acme thread form has a 29° thread angle with a thread height half of the pitch; the apex and valley are flat. This shape is easier to machine (faster cutting, longer tool life) than is a square thread. The tooth shape also has a wider base which means it is stronger (thus, the screw can carry a greater load) than a similarly sized square thread. [37]

Finite element model (FEM) analysis has been widely used to evaluate the stress in peri-implant bone. The 2D FEM is a very simple and schematic model. It is designed to clarify the "principal effect" that can be "hidden" in the 3D FEM as a result of the complex geometry of real 3D objects (e.g., tooth, maxilla, etc.,). [38] Therefore, the 2D model was only used for preliminary qualitative analysis in the present study.

Until date, there are no reports documenting the use of acme threads for dental implants as well as use of standard diameter short implants under immediate loading protocol. The microthreads used until now, are a form of triangular thread, but in this study, we are using the acme thread form as a microthread, which is again a novel approach.

The aim of the present study is to evaluate the biomechanical response of standard diameter tapered implants of varying lengths (6 mm and 10 mm) incorporating microthreads for crestal portion and acme threads for body portion placed in D4 bone under immediate loading protocol.


   Materials and Methods Top


2D FEMs of maxillary posterior section of bone were created. The bone was modeled as a cancellous core D4 bone surrounded by a 0.5 mm thick cortical layer. Tapered implants of length 6 mm and 10 mm with standard diameter of 3.75 mm were used for the study [Figure 1] and [Figure 2]. All the FEMs were created using a software program named ANSYS classic, version 11.
Figure 1: Standard diameter implant of 6 mm length in D4 bone with cortical bone thickness of 0.5 mm

Click here to view
Figure 2: Standard diameter implant of 10 mm length in D4 bone with cortical bone thickness of 0.5 mm

Click here to view


Material properties: All materials used in the models were considered to be homogeneous and linearly elastic. The elastic properties used were taken from the literature [39],[40] [Table 1].
Table 1: Material properties

Click here to view


Interface condition: To simulate the interface of an immediately loaded implant, a frictional coefficient of 0.6 [41] was applied at bone implant interface.

Implant design: The implant design incorporates microthreads at the crestal part (2 mm) with 0.2 mm screw pitch and 29° thread angle. The rest of the implant body incorporates acme threads with 0.8 mm screw pitch and 29° thread angle [37] [Figure 3].
Figure 3: The 6 mm and 10 mm length implant design - microthreads at the crestal part (2 mm) with 0.2 mm screw pitch and 29° angle and rest implant body with acme threads with 0.8 mm screw pitch and 29° angle

Click here to view


Elements and nodes: The FEM model composed of 4195 nodes and 4087 elements for 6 mm implant and bone block of 10 mm height and 20 mm length, for 10 mm tapered implant the nodes were 5856 and elements were 5732 and bone block of 15 mm height and 20 mm length.

Loading conditions: Loads of 100 N were applied in the vertical direction (along the long axis of the implant) and an oblique direction (at an angle of 45° to the vertical) [Figure 4]a and b.
Figure 4: (a and b) Force directed along long axis of implant and at 45° to long axis of implant

Click here to view


Parameters analyzed were:

  • Total deformation (Micro-movement)
  • Von mises stress.



   Results Top


The values for total deformation when using vertical loads (100 N) were 129 μm and 82.2 μm for 6 mm and 10 mm implant [Figure 5]a and b respectively and with oblique loads the values were 114 μm for 6 mm and 83.3 μm for 10 mm implant [Figure 6]a and b.
Figure 5: (a) Total deformation for 6 mm implant with vertical (along long axis) forces; (b) total deformation for 10 mm implant with vertical (along long axis) forces

Click here to view
Figure 6: (a) Total deformation for 6 mm implant with oblique (45° along to long axis) forces; (b) total deformation for 10 mm implant with oblique (45° along to long axis) forces

Click here to view


Von mises stress values were 94.2 MPa for 6 mm implant and 47.2 MPa for 10 mm implant respectively when vertical loads were used [Figure 7]a and b. Stress values were more for oblique loading i.e., 306.6 MPa and 204.4 MPa for 6 mm and 10 mm implants respectively [Figure 8]a and b. The results of total deformation (micro-movement), Von mises stress were found to be lower for tapered long implant (10 mm) than short implant (6 mm) while using both vertical as well as oblique loading [Figure 9] and [Figure 10].
Figure 7: (a) Von Mises stress for 6 mm implant under vertical loading; (b) Von Mises stress for 10 mm implant under vertical loading

Click here to view
Figure 8: (a) Von Mises stress for 6 mm implant under oblique (45° to long axis) loading forces; (b) Von Mises stress for 10 mm implant under oblique (45° to long axis) loading

Click here to view
Figure 9: Graph showing total deformation for 6 mm and 10 mm implant under vertical and oblique (100 N) forces

Click here to view
Figure 10: Graph showing Von Mises stress for 6 mm and 10 mm implant under vertical and oblique (100 N) forces

Click here to view



   Discussion Top


The present study evaluates the effects of implant lengths (6 mm and 10 mm) on immediately loaded tapered implants placed in maxillary posterior region. In maxillary posterior region presence of poor bone quality and reduced bone height, makes short implants a favorable choice.

FEA, a computer based technique calculates the behavior of engineering structures and their strength numerically. In the FEM, a structure is broken down into many small simple blocks or elements. A simple set of equations describes the behavior of an individual element relatively. The structure will be built fully by joining together these set of elements, so the behavior of the whole structure will be described by extremely large set of equations, which were actually the equations describing the behavior of individual elements joined together. The behavior of individual elements is assessed by computer from the solutions. Hence, the stress and deflection of all parts of the structure can be calculated. [42],[43]

The most valid approach for implant placement is two-stage protocol. Recently, immediate functional loading has gained importance and comparable results were found in a single stage surgical procedure. [44] Good primary stability, controlled loading conditions and osseoconductive implant surface are the expected advantageous results for immediate functional loading. [45]

Careful consideration of fixture placement, prosthesis design, nature and magnitude of occlusal forces is essential, in order to achieve optimized biomechanical conditions in implant-supported suprastructures. [46] When applying FEM analysis to dental implants, it is important to consider oblique occlusal force because they represent more realistic occlusal directions and for a given force, will result in localized stress in cortical bone. [47] Loads of 100 N were applied in the vertical direction (along the long axis of the implant) and an oblique direction (at an angle of 45° to the vertical) in the present study.

The initial implant mobility does not necessarily prevent osseointegration. [48] In general, from uncontrolled masticatory forces; micro motion at the implant interface has to be distinguished. Cameron et al.[49] reported that osseointegration cannot be achieved with macro-movements. However, micro-movements are not a problem. There is a lack of a consistent terminology on the definition of micro and macro-movements. It has been suggested that a movement of 150 μm or more results in soft connective tissue apposition at bone implant interface and a movement of 30 μm or less has no adverse effect on integration. [50],[51],[52] The results of the present study show all the micro-movement values within this range. The values are lower for long implant (10 mm) than for 6 mm implant.

Available bone is particularly important in implant dentistry. It describes the external architecture or volume of the edentulous area considered for implants. In addition, quality or density describes the internal structure of bone, which reflects the strength of the bone. Type 4 bone i.e., D4 bone has little cortical bone thickness and minimal internal strength. [53] As compared with more dense bone, increased clinical failure rates in poor quality, porous bone, have been well-documented. [54],[56] Jaffin and Berman, [57] in a 5-year analysis of Branemark implants, reported that out of 105 implants placed in Type 4 bones, 35% failed and among 949 implants placed in Types 1, 2 and 3 bones, only 3% of the implants were lost. Bass and Triplett [58] also revealed that bone quality four exhibited the greatest failure rate. In patients with implant retained overdentures, highest risk for implant failure (45%) was reported in dental arches with bone quality 4 by Hutton et al. in a prospective study of 510 Branemark implants. [59] Increase the number of implants or an implant design with greater surface area may be the choice to decrease the stress in D4 bone quality. [33],[53],[60],[61]

Threaded implants increase the surface area for osseous integration and are generally preferred to smooth cylindrical ones. [62] The neck of the implant is called crest module. In the presence of a smooth neck, negligible forces are transmitted to the marginal bone leading to its resorption. However, the presence of retentive elements at the implant neck will dissipate some forces leading to the maintenance of the crestal bone height accordingly to Wolff's law. [35] A clinical trial [63] demonstrated possible preservation of crestal bone contact with implant systems using microthreads. Significantly lower amounts of bone loss, with an implant system that incorporates microthread retention elements at the implant neck was reported by Norton. [64] In the present study microthreads are used at the crestal module of the implant and the rest of the implant body consists of acme threads. Microthreads used previously were a form of triangular threads, but in our study, we used acme thread form with 29° thread angle as microthread.

When created prior to 1895, Acme screw threads were intended to replace square threads and a variety of threads of other forms used chiefly for the purpose of traversing motion on machines, tools, etc., Acme screw threads are now extensively used for a variety of purposes. Long-length acme threads are used for controlled movements on machine tools, testing machines, jacks, aircraft flaps and conveyors. Short-length threads are used on valve stems, hose connectors, bonnets on pressure cylinders, steering mechanisms and camera lens movement. They are best suited for applications that warrant large load bearing capacity and high accuracy. [37] We have used acme threads for the body of the implant to increase the load bearing characteristic of implant, particularly in the presence of weak bone (D4) and it gave promising results. The results of our study shows highest stress concentration at the cortical bone level of D4 bone where trabecular bone is sparse and cannot sustain loads.

Longer implants have been observed to score better than shorter ones. [65],[66] When a problem of severe atrophy of the jaws is encountered, there have been many different approaches in solving this condition by prosthetic reconstruction. In the presence of reduced alveolar bone height, the short dental implants have recently become available and offer the clinicians a pragmatic option to facilitate prosthetic restoration in the face of anatomic limitation. [67] Renouard and Nisand [46] reported a trend of increased failure rate due to the use of short or wide implants, when reviewing the effects of implant length and diameter. The survival rates of short-or wide-diameter implants were comparable to those of longer implants and implants with standard diameters, when the bone density, surface characteristics of the implant, operator's surgical skill and indications for treatment during the surgical preparation were considered. The results of our study are in accordance with other studies with lower stress values for long implant than short 6 mm implant. In our study, we found that stresses are 49.9% increased with vertical loading and 33.3% increased when oblique forces when used for 6 mm short implant as compared with 10 mm long tapered implant.

The presence of poor quality bone (D4) in the maxillary posterior region is a common finding. Usage of acme threads presents a good option to increase the load bearing characteristic of implant when poor bone quality is present. As stress values are more for oblique loading, eccentric loads have to be avoided during healing phases, particularly for short implants.

Limitations of this study are the simplified geometry of the bone model, material properties assigned and static occlusal force. Even though the strength of a bone block is similar to that of the jaw bone, the stress patterns might vary with the bone geometry. The material properties of the FEM maxillary were assumed to be isotropic and homogenous whereas, consideration of the anisotropic and inhomogeneous properties is still needed in future studies. Although oblique loading has been suggested to represent a realistic occlusal load, [68] chewing movement, especially with dynamic loading simulations, needs to be considered in future investigations.


   Summary and Conclusion Top


The present study evaluates the effects of implant lengths (6 mm and 10 mm) on immediately loaded tapered implants placed in maxillary posterior region. Within the limitations of the 2D FEA study, the following conclusions can be drawn:

  • Short implants can be successfully placed in poor bone quality under immediate loading protocol
  • During the initial phases of implant healing, avoidance of oblique forces with optimally designed implant superstructures will help to reduce stresses around short implant
  • Incorporation of microthreads at the crestal portion helped in concentration of stresses in the cortical bone in D4 bone where trabecular bone is sparse
  • Acme threads are best suited for applications that warrant large load bearing capacity and high accuracy. Usage of Acme threads for body portion of the implants gave promising results.


Further randomized clinical trials are needed to validate results of FEM study.

 
   References Top

1.Chou HY, Müftü S, Bozkaya D. Combined effects of implant insertion depth and alveolar bone quality on periimplant bone strain induced by a wide-diameter, short implant and a narrow-diameter, long implant. J Prosthet Dent 2010;104:293-300.  Back to cited text no. 1
    
2.Brånemark PI, Adell R, Breine U, Hansson BO, Lindström J, Ohlsson A. Intra-osseous anchorage of dental prostheses. I. Experimental studies. Scand J Plast Reconstr Surg 1969;3:81-100.  Back to cited text no. 2
    
3.Albrektsson T, Brånemark PI, Hansson HA, Lindström J. Osseointegrated titanium implants. Requirements for ensuring a long-lasting, direct bone-to-implant anchorage in man. Acta Orthop Scand 1981;52:155-70.  Back to cited text no. 3
    
4.Brånemark PI. Osseointegration and its experimental background. J Prosthet Dent 1983;50:399-410.  Back to cited text no. 4
    
5.Jaffin RA, Kumar A, Berman CL. Immediate loading of implants in partially and fully edentulous jaws: A series of 27 case reports. J Periodontol 2000;71:833-8.  Back to cited text no. 5
[PUBMED]    
6.Horiuchi K, Uchida H, Yamamoto K, Sugimura M. Immediate loading of Brånemark system implants following placement in edentulous patients: A clinical report. Int J Oral Maxillofac Implants 2000;15:824-30.  Back to cited text no. 6
[PUBMED]    
7.Rocci A, Martignoni M, Gottlow J, Rangert B. Immediate function of single and partial reconstructions in the maxilla using MK IV fixtures: A retrospective analysis. Appl Osseointegration Res2001;2:22-6.  Back to cited text no. 7
    
8.Cooper LF, Rahman A, Moriarty J, Chaffee N, Sacco D. Immediate mandibular rehabilitation with endosseous implants: Simultaneous extraction, implant placement, and loading. Int J Oral Maxillofac Implants 2002;17:517-25.  Back to cited text no. 8
[PUBMED]    
9.Degidi M, Piattelli A. Immediate functional and non-functional loading of dental implants: A 2- to 60-month follow-up study of 646 titanium implants. J Periodontol 2003;74:225-41.  Back to cited text no. 9
[PUBMED]    
10.Degidi M, Piattelli A, Felice P, Carinci F. Immediate functional loading of edentulous maxilla: A 5-year retrospective study of 388 titanium implants. J Periodontol 2005;76:1016-24.  Back to cited text no. 10
[PUBMED]    
11.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. 11
[PUBMED]    
12.Clelland NL, Ismail YH, Zaki HS, Pipko D. Three-dimensional finite element stress analysis in and around the Screw-Vent implant. Int J Oral Maxillofac Implants 1991;6:391-8.  Back to cited text no. 12
[PUBMED]    
13.Stegaroiu R, Sato T, Kusakari H, Miyakawa O. Influence of restoration type on stress distribution in bone around implants: A three-dimensional finite element analysis. Int J Oral Maxillofac Implants 1998;13:82-90.  Back to cited text no. 13
[PUBMED]    
14.Isidor F. Loss of osseointegration caused by occlusal load of oral implants. A clinical and radiographic study in monkeys. Clin Oral Implants Res 1996;7:143-52.  Back to cited text no. 14
[PUBMED]    
15.Ostman PO, Hellman M, Sennerby L. Direct implant loading in the edentulous maxilla using a bone density-adapted surgical protocol and primary implant stability criteria for inclusion. Clin Implant Dent Relat Res 2005;7 Suppl 1:S60-9.  Back to cited text no. 15
[PUBMED]    
16.Rocci A, Martignoni M, Gottlow J. Immediate loading in the maxilla using flapless surgery, implants placed in predetermined positions, and prefabricated provisional restorations: A retrospective 3-year clinical study. Clin Implant Dent Relat Res 2003;5 Suppl 1:29-36.  Back to cited text no. 16
[PUBMED]    
17.Klinger A, Mijiritsky E, Kohavi D. Biological and clinical rationale for early implant loading. Compend Contin Educ Dent 2006;27:29-34.  Back to cited text no. 17
    
18.Morton D, Jaffin R, Weber HP. Immediate restoration and loading of dental implants: Clinical considerations and protocols. Int J Oral Maxillofac Implants 2004;19 Suppl: 103-8.  Back to cited text no. 18
[PUBMED]    
19.Cochran DL. A comparison of endosseous dental implant surfaces. J Periodontol 1999;70:1523-39.  Back to cited text no. 19
[PUBMED]    
20.Le Guéhennec L, Soueidan A, Layrolle P, Amouriq Y. Surface treatments of titanium dental implants for rapid osseointegration. Dent Mater 2007;23:844-54.  Back to cited text no. 20
    
21.Glauser R, Lundgren AK, Gottlow J, Sennerby L, Portmann M, Ruhstaller P, et al. Immediate occlusal loading of Brånemark tiunite implants placed predominantly in soft bone: 1-year results of a prospective clinical study. Clin Implant Dent Relat Res 2003;5 Suppl 1:47-56.  Back to cited text no. 21
[PUBMED]    
22.Brånemark PI, Hansson BO, Adell R, Breine U, Lindström J, Hallén O, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl 1977;16:1-132.  Back to cited text no. 22
    
23.Adell R, Lekholm U, Rockler B, Brånemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;10:387-416.  Back to cited text no. 23
    
24.Listgarten MA, Lang NP, Schroeder HE, Schroeder A. Periodontal tissues and their counterparts around endosseous implants corrected and republished with original paging, article orginally printed in Clin Oral Implants Res 1991 Jan-Mar; 2 (1):1-19. Clin Oral Implants Res 1991;2:1-19.  Back to cited text no. 24
[PUBMED]    
25.Misch CE, Wang HL. Immediate occlusal loading for fixed prostheses in implant dentistry. Dent Today 2003;22:50-6.  Back to cited text no. 25
    
26.Winkler S, Morris HF, Ochi S. Implant survival to 36 months as related to length and diameter. Ann Periodontol 2000;5:22-31.  Back to cited text no. 26
[PUBMED]    
27.Graves SL, Jansen CE, Siddiqui AA, Beaty KD. Wide diameter implants: Indications, considerations and preliminary results over a two-year period. Aust Prosthodont J 1994;8:31-7.  Back to cited text no. 27
[PUBMED]    
28.Renouard F, Arnoux JP, Sarment DP. Five-mm-diameter implants without a smooth surface collar: Report on 98 consecutive placements. Int J Oral Maxillofac Implants 1999;14:101-7.  Back to cited text no. 28
[PUBMED]    
29.Blatz MB, Strub JR, Gläser R, Gebhardt W. Use of wide-diameter and standard-diameter implants to replace single molars: Two case presentations. Int J Prosthodont 1998;11:356-63.  Back to cited text no. 29
    
30.Frandsen PA, Christoffersen H, Madsen T. Holding power of different screws in the femoral head. A study in human cadaver hips. Acta Orthop Scand 1984;55:349-51.  Back to cited text no. 30
[PUBMED]    
31.Ivanoff CJ, Sennerby L, Johansson C, Rangert B, Lekholm U. Influence of implant diameters on the integration of screw implants. An experimental study in rabbits. Int J Oral Maxillofac Surg 1997;26:141-8.  Back to cited text no. 31
[PUBMED]    
32.Brunski JB. Biomaterials and biomechanics in dental implant design. Int J Oral Maxillofac Implants 1988;3:85-97.  Back to cited text no. 32
[PUBMED]    
33.Siegele D, Soltesz U. Numerical investigations of the influence of implant shape on stress distribution in the jaw bone. Int J Oral Maxillofac Implants 1989;4:333-40.  Back to cited text no. 33
[PUBMED]    
34.Vidyasagar L, Apse P. Dental implant design and biological effects on bone-implant interface. Stomatologija Baltic Dental Maxillofac J 2004;6:51-4.  Back to cited text no. 34
    
35.Hansson S. The implant neck: Smooth or provided with retention elements. A biomechanical approach. Clin Oral Implants Res 1999;10:394-405.  Back to cited text no. 35
[PUBMED]    
36.Kahnberg KE. Immediate implant placement in fresh extraction sockets: A clinical report. Int J Oral Maxillofac Implants 2009;24:282-8.  Back to cited text no. 36
[PUBMED]    
37.American Society of Mechanical Engineers. Acme Screw Threads, Asme b1.5-1997. USA: Asme Press; 1997.  Back to cited text no. 37
    
38.Menicucci G, Mossolov A, Mozzati M, Lorenzetti M, Preti G. Tooth-implant connection: Some biomechanical aspects based on finite element analyses. Clin Oral Implants Res 2002;13:334-41.  Back to cited text no. 38
[PUBMED]    
39.Cibirka RM, Razzoog ME, Lang BR, Stohler CS. Determining the force absorption quotient for restorative materials used in implant occlusal surfaces. J Prosthet Dent 1992;67:361-4.  Back to cited text no. 39
[PUBMED]    
40.Richter EJ, Orschall B, Jovanovic SA. Dental implant abutment resembling the two-phase tooth mobility. J Biomech 1990;23:297-306.  Back to cited text no. 40
[PUBMED]    
41.Grant JA, Bishop NE, Götzen N, Sprecher C, Honl M, Morlock MM. Artificial composite bone as a model of human trabecular bone: The implant-bone interface. J Biomech 2007;40:1158-64.  Back to cited text no. 41
    
42.Assaf JH, Filho AM, Zanatta FB. Short implants with single-unit restorations in posterior regions with reduced height-A retrospective study. Braz J Oral Sci 2010;9:493-7.  Back to cited text no. 42
    
43.Pierrisnard L, Hure G, Barquins M, Chappard D. Two dental implants designed for immediate loading: A finite element analysis. Int J Oral Maxillofac Implants 2002;17:353-62.  Back to cited text no. 43
[PUBMED]    
44.Buser D, Mericske-Stern R, Bernard JP, Behneke A, Behneke N, Hirt HP, et al. Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multi-center study with 2359 implants. Clin Oral Implants Res 1997;8:161-72.  Back to cited text no. 44
[PUBMED]    
45.Vanden Bogaerde L, Rangert B, Wendelhag I. Immediate/early function of Brånemark system tiunite implants in fresh extraction sockets in maxillae and posterior mandibles: An 18-month prospective clinical study. Clin Implant Dent Relat Res 2005;7 Suppl 1:S121-30.  Back to cited text no. 45
[PUBMED]    
46.Renouard F, Nisand D. Impact of implant length and diameter on survival rates. Clin Oral Implants Res 2006;17 Suppl 2:35-51.  Back to cited text no. 46
[PUBMED]    
47.Rangert B, Sennerby L, Meredith N, Brunski J. Design, maintenance and biomechanical considerations in implant placement. Dent Update 1997;24:416-20.  Back to cited text no. 47
[PUBMED]    
48.Ivanoff CJ, Sennerby L, Lekholm U. Influence of initial implant mobility on the integration of titanium implants. An experimental study in rabbits. Clin Oral Implants Res 1996;7:120-7.  Back to cited text no. 48
[PUBMED]    
49.Cameron H, Macnab I, Pilliar R. Porous surfaced vitallium staples. S Afr J Surg 1972;10:63-70.  Back to cited text no. 49
[PUBMED]    
50.Pilliar RM, Lee JM, Maniatopoulos C. Observations on the effect of movement on bone ingrowth into porous-surfaced implants. Clin Orthop Relat Res 1986;208:108-13.  Back to cited text no. 50
[PUBMED]    
51.Brunski JB. Biomechanical factors affecting the bone-dental implant interface. Clin Mater 1992;10:153-201.  Back to cited text no. 51
[PUBMED]    
52.Szmukler-Moncler S, Salama H, Reingewirtz Y, Dubruille JH. Timing of loading and effect of micromotion on bone-dental implant interface: Review of experimental literature. J Biomed Mater Res 1998;43:192-203.  Back to cited text no. 52
[PUBMED]    
53.Misch CE. Density of bone: Effect on treatment plans, surgical approach, healing, and progressive boen loading. Int J Oral Implantol 1990;6:23-31.  Back to cited text no. 53
[PUBMED]    
54.Sato Y, Wadamoto M, Tsuga K, Teixeira ER. The effectiveness of element downsizing on a three-dimensional finite element model of bone trabeculae in implant biomechanics. J Oral Rehabil 1999;26:288-91.  Back to cited text no. 54
[PUBMED]    
55.Ichikawa T, Kanitani H, Wigianto R, Kawamoto N, Matsumoto N. Influence of bone quality on the stress distribution. An in vitro experiment. Clin Oral Implants Res 1997;8:18-22.  Back to cited text no. 55
[PUBMED]    
56.Holmgren EP, Seckinger RJ, Kilgren LM, Mante F. Evaluating parameters of osseointegrated dental implants using finite element analysis: A two-dimensional comparative study examining the effects of implant diameter, implant shape, and load direction. J Oral Implantol 1998;24:80-8.  Back to cited text no. 56
[PUBMED]    
57.Jaffin RA, Berman CL. The excessive loss of Branemark fixtures in type IV bone: A 5-year analysis. J Periodontol 1991;62:2-4.  Back to cited text no. 57
[PUBMED]    
58.Bass SL, Triplett RG. The effects of preoperative resorption and jaw anatomy on implant success. A report of 303 cases. Clin Oral Implants Res 1991;2:193-8.  Back to cited text no. 58
[PUBMED]    
59.Hutton JE, Heath MR, Chai JY, Harnett J, Jemt T, Johns RB, et al. Factors related to success and failure rates at 3-year follow-up in a multicenter study of overdentures supported by Brånemark implants. Int J Oral Maxillofac Implants 1995;10:33-42.  Back to cited text no. 59
[PUBMED]    
60.Sahin S, Cehreli MC, Yalçin E. The influence of functional forces on the biomechanics of implant-supported prostheses: A review. J Dent 2002;30:271-82.  Back to cited text no. 60
    
61.Papavasiliou G, Kamposiora P, Bayne SC, Felton DA. Three-dimensional 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.  Back to cited text no. 61
[PUBMED]    
62.Misch CE, Bidez MW. A scientific rationale for dental implant design. In: Misch CE, editor. Contemporary Implant Dentistry. 3 rd ed. St. Louis: Mosby; 2007. p. 329-44.  Back to cited text no. 62
    
63.Abrahamsson I, Berglundh T. Tissue characteristics at microthreaded implants: An experimental study in dogs. Clin Implant Dent Relat Res 2006;8:107-13.  Back to cited text no. 63
[PUBMED]    
64.Norton MR. Marginal bone levels at single tooth implants with a conical fixture design. The influence of surface macro- and microstructure. Clin Oral Implants Res 1998;9:91-9.  Back to cited text no. 64
[PUBMED]    
65.Quirynen M, Naert I, van Steenberghe D. Fixture design and overload influence marginal bone loss and fixture success in the Brånemark system. Clin Oral Implants Res 1992;3:104-11.  Back to cited text no. 65
[PUBMED]    
66.Sennerby L, Roos J. Surgical determinants of clinical success of osseointegrated oral implants: A review of the literature. Int J Prosthodont 1998;11:408-20.  Back to cited text no. 66
    
67.Gentile MA, Chuang SK, Dodson TB. Survival estimates and risk factors for failure with 6 × 5.7-mm implants. Int J Oral Maxillofac Implants 2005;20:930-7.  Back to cited text no. 67
    
68.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. 68
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
 
 
    Tables

  [Table 1]



 

Top
   
 
  Search
 
  
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    Abstract
   Introduction
    Materials and Me...
   Results
   Discussion
    Summary and Conc...
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed2437    
    Printed76    
    Emailed1    
    PDF Downloaded307    
    Comments [Add]    

Recommend this journal