Should oral implants be splinted in a mandibular implant-supported fixed complete denture? A 3-dimensional-model finite element analysis Angel Alvarez-Arenal, DDS, PhD,a Aritza Brizuela-Velasco, DDS,b Hector DeLlanos-Lanchares, DDS,c and Ignacio Gonzalez-Gonzalez, DDS, PhDd School of Dentistry, University of Oviedo, Oviedo, Spain Statement of problem. The design of a mandibular fixed complete denture can influence periimplant bone loss. However, the design that transfers the greatest stress to the periimplant bone is not well documented. Purpose. The purpose of this study was to assess the stress distribution associated with splinted and nonsplinted implant-supported mandibular fixed complete denture designs. Material and methods. Three-dimensional finite element models simulating 6 osseointegrated implants were created in the mandible to support a cobalt-chromium alloy and feldspathic porcelain veneering framework. One model simulated a 1-piece framework, and the other models simulated 2-piece and 3-piece frameworks. Axial and oblique loads were applied to the frameworks. Results. For all the models, the greatest stress values were recorded in the periimplant bone of posterior implants, with differences between the left and right sides. The axial load transferred greater stress values to the periimplant bone than did the oblique load. The lowest periimplant bone stress values were observed in the 3-piece framework model at all implant locations, with the exception of implants placed in the canine region. Conclusions. A framework separated into 3 pieces transfers the least stress to the periimplant bone. (J Prosthet Dent 2014;-:---)

Clinical Implications A 3-piece framework provides more favorable results in the treatment of an edentulous mandible with an implant-supported complete-arch fixed mandibular prosthesis than a 2-piece structure or a 1-piece structure that splints all the implants.

Progressive bone loss around implants is the main factor in implantsupported restoration failure. Bone loss may be caused by either mechanical (occlusal overload) or biologic (periimplantitis) elements, or by a combination of both. Regardless of periimplantitis, several in vivo and in vitro studies have found the influence of occlusal overload in the loss of periimplant marginal bone.1-4 Occlusal force a

generates a certain amount of stress on the framework, which, in turn, is transferred to the implant and the periimplant bone. However, the stress/ strain values transmitted to the implant and the alveolar bone depend on several parameters. The most important are occlusal force characteristics (intensity, direction, duration, speed), implant factors (number, diameter, length), implant-abutment connection,

Professor and Head, Department of Prosthodontics and Occlusion. Clinical Assistant Professor, Department of Prosthodontics and Occlusion. c Clinical Assistant Professor, Department of Prosthodontics and Occlusion. d Associate Professor, Department of Prosthodontics and Occlusion. b

Alvarez-Arenal et al

bone quality and density, and prosthetic restoration material and design. With regard to prosthetic design, the position and number of implants and whether they are splinted are important factors in planning the treatment of an implant-supported fixed mandibular complete-arch prosthesis to avoid the effect of cantilevers. Nevertheless, prospective studies have reported that cantilevers do not adversely

2

Volume affect survival rates, nor do they increase biologic complications in partial fixed prostheses.5-8 The framework of a fixed implant-supported complete-arch mandibular prosthesis may be conceived as a single 1-piece superstructure, a 2-piece superstructure separated at the midline, or a 3-piece superstructure divided into 1 anterior and 2 posterior sections. Which of these designs transfers the greatest stress to the periimplant bone is a question that remains unanswered. By using a single structure, the maximum load applied to each implant is less than the total load applied, but this model creates bending moments and a more complex stress distribution.9,10 Furthermore, periimplant stress may increase owing to mandibular deflection that cannot be counterbalanced because of a lack of periodontal ligament.11-13 This is also a matter for debate, as some studies have stated that the prosthetic structure itself can counteract mandibular deflection.14,15 By contrast, a superstructure separated into 2 or particularly 3 pieces would be expected to reduce this deflection, as long as the posterior section were independent of the anterior section. Whether this design reduces the stress received by the implants and the surrounding bone is not sufficiently clear. Some studies have found lower stress values for 1-piece superstructures compared with segmented superstructures and also for partial fixed prostheses splinting periodontally affected crowns of teeth.16-20 However, other studies have found that splinting implants in partial fixed, complete-arch, or overdenture prostheses does not improve the biomechanical environment or the success rates when compared with unsplinted implants.14,21-24 Therefore, the assessment of the biomechanical benefits of splinting or not splinting the implants of a mandibular fixed complete denture requires further clarification. The hypothesis stated that a mandibular implant-supported fixed complete denture separated into 2 or 3 pieces decreases stress value in the periimplant

bone when compared with a 1-piece fixed complete denture; the purpose of the present study was to examine differences in stress distribution between splinted and unsplinted implants for a mandibular fixed complete denture in implant and periimplant bone under axial and nonaxial occlusal load.

MATERIAL AND METHODS Finite element analysis Three-dimensional finite element models were created in this study. Each model was constructed on the basis of a completely edentulous mandible with the following dimensions: the intercondylar distance was 108 mm; the symphyseal height was 32 mm; the distance between the chin and the mandibular angle was 71 mm; and the distance between the mandibular angle and the coronoid apophysis was 67 mm. Type 2 bone quality (according to the Lekholm and Zarb25 classification) was used, because Type 2 and Type 3 are the bone types most commonly found in the mandible.26 In the posterior edentulous segment, the periimplant cortical and trabecular bone was assumed to be 23 mm in inferosuperior height and 12 mm in buccolingual width. In the model referred to, 6 implants were placed in the mandibular canine region (the separation between implant centers was set at 27 mm); the first premolar region (the separation between implant centers located at the canine and first premolar positions was set at 7 mm); and the first molar region (the separation between implant centers located at the first premolar and first molar positions was set at 15 mm) of each hemiarcade. The geometry of the implants (Certain Prevail; Biomet 3i, Implants Innovations Inc) (4.0 mm body diameter, 4.1 mm diameter platform, and 10 mm length) was used as a reference to model the 6 threaded implants. Furthermore, 6 solid abutments (ITI; Institut Straumann AG), 7 mm in height and made of titanium, were modeled and attached to the implants to support the prosthesis framework.

The Journal of Prosthetic Dentistry

-

Issue

-

The framework was a superstructure made of a cobalt-chromium alloy with 6 interior retainers to be cemented on each abutment and veneered with feldspathic porcelain (occlusal thickness, 1 mm). The framework had no posterior cantilevers to avoid concentrations of stress in the periimplant bone of the distal implants. This stress would not be reduced by the use of distal tilted implants (suggested by Baggi et al27), because none of the implants were fitted in a tilted position in the present design. One finite element model simulated a 1-piece fixed complete denture, another simulated a 2-piece superstructure divided at the midline, and a third simulated a 3-piece superstructure with 2 posterior sections and an anterior section.

Material properties and interface conditions All the materials used in these models were considered to be linearly elastic, homogeneous, and isotropic, and the values of the Young modulus and Poisson ratio were taken from published data (Table I).10,28-31 A system made up of one or more elements is homogeneous only when its properties are identical in all its parts. Moreover, if the directional properties (for example, thermal dilatation, mechanical resistance, or the speed of light) are the same in all directions, it is considered as an isotropic material. Static linear models have also been used in studies with finite elements and are considered reliable if the structure shows linear elasticity. Bone has neither isotropic properties nor linear elasticity. However, these characteristics permit certain simplifications and produce results at a reasonable computational cost. Furthermore, the bone-implant interface was considered to be perfect, with 100% osseointegration, and passive fit between the abutments and the superstructure was considered to be perfect, without any misfit. The resin layer between abutments and the framework retainers was not considered and was assumed to be completely

Alvarez-Arenal et al

-

2014

3

Mechanical properties of materials and structures adopted for 3-dimensional finite element analysis

Table I.

Structure

Young Modulus (GPa)

Poisson Ratio

Implant

110.0

0.35

Abutment

107.2

0.33

Framework prosthesis

218.0

0.33

Feldspathic porcelain10

Veneering framework prosthesis

68.9

0.28

Cortical bone31

Periimplant bone

13.70

0.30

Cancellous bone31

Periimplant bone

1.37

0.31

Material Titanium28 29

Titanium alloy

30

CoCr alloy

Table II.

Occlusal force on each tooth

Tooth

% Occlusal Force Occlusal Force Occlusal Load on Each Tooth on Each Tooth (N) Applied (N)

Central incisor

0.7

7.1

7.2

Lateral incisor

0.5

5.1

5.1

Canine

1.5

15.4

40.3

First premolar

3.1

31.7

76.7

Second premolar

4.0

41.0

95.9

First molar

15.8

161.8

286.7

Second molar

24.4

249.9

0

Measured according to Watanabe et al.32 Occlusal load applied simultaneously to each tooth. Occlusal force corresponding to second molar (249.9 N) was divided among other teeth except incisors.

bonded without any loosening. The bonding between the framework and veneering material (feldspathic porcelain) was also assumed to be firm, effective, and without any loosening.

Loading and boundary conditions Because the occlusal force system acting on the dental arches is complex and hardly comparable with any other force system in the human body, the representation of these forces was simplified in accordance with the Watanabe et al32 survey. Table II shows the distribution and load applied to each tooth. In all models, axial and offaxial loadings were applied alternatively. The oblique loads were 6 degrees from the vertical axis for posterior teeth and 35 degrees for anterior teeth. These angles were chosen because the main component of the occlusal force was

Alvarez-Arenal et al

quasivertical to the plane of occlusion, particularly in posterior regions, and because there is a clear consensus that the horizontal component of the nonaxial loads is responsible for higher stress values when compared with axial forces.18,32-36 However, in one study with an animal model, osseointegration was not found to deteriorate with nonaxial forces.37 In all trials, the temporomandibular joint was assumed to be fixed at the condylar level. These finite element models were created and meshed by using commercial 3-dimensional finite element software (Ansys 11.0; Swanson Analysis Systems Inc) and were composed of 121 249 elements and 166 608 nodes.

RESULTS Table III shows the implant stress for each model in response to axial and

nonaxial load. The stress ranged from 1677.8 MPa for the implant at the left canine position of the 2-piece superstructure under nonaxial load to 4668.9 MPa for the implant at the left first molar position of the 3-piece superstructure under axial load. In general, implants in posterior locations withstood more stress than those placed in a more mesial position, regardless of the superstructure model or the force direction. The stress values were also greater under axial loads than nonaxial loads for the 3 models. With the exception of the implant at the left canine position mentioned earlier, the 1-piece fixed complete denture was the model that transferred the lowest stress to the implants, whereas the highest stress values were observed in the 3-piece superstructure model. The periimplant bone stress values ranged from 20.3 MPa for the 1-piece fixed complete denture under nonaxial load to 143.3 MPa for the 2-piece superstructure under axial load (see Table III). Again, nonaxial forces generated less stress in the surrounding implant bone than did axial forces. Independently of the force direction, the 3-piece superstructure was the model that transferred the lowest stress values to the periimplant bone for posterior implants, whereas the lowest values for anterior implants were obtained with the 1-piece fixed complete denture model. Regardless of the occlusal load direction, the stress was located in the distal and lingual areas of the coronal third of the periimplant bone surrounding the posterior implants. This was also observed for anterior implants, although only in the 3-piece superstructure model (Figs. 1-6).

DISCUSSION In the present study, for the 3 models, the stress distribution in the implants and the periimplant bone was not uniform. Regardless of the superstructure type or force direction, implants located in the left alveolar process in the premolar and molar positions received higher loads than

4

Volume

Table III.

-

Issue

-

Maximum von Mises stress values (MPa)

Framework 1-piece

Framework 2-piece

Framework 3-piece

Location of Implants

Axial

Nonaxial

Axial

Nonaxial

Axial

Nonaxial

First molar right

103.2 (3698.3)

101.7 (3285.9)

143.3 (3776.0)

138.2 (3348.7)

70.3 (3982.5)

68.7 (3515.6)

First premolar right

97.9 (3767.1)

95.3 (3340.0)

97.1 (3954.0)

94.9 (3497.8)

67.9 (4143.9)

65.6 (3650.5)

Canine right

23.5 (2794.4)

21.4 (2474.8)

33.5 (2841.7)

31.7 (2511.8)

47.7 (2767.9)

44.6 (2445.7)

Canine left

22.6 (2548.7)

20.3 (2260.1)

32.2 (1885.2)

30.9 (1677.8)

47.2 (1930.9)

43.8 (1703.8)

First premolar left

73.4 (4288.0)

69.3 (3795.6)

93.7 (4375.1)

88.2 (3875.5)

57.8 (4445.5)

55.7 (3923.0)

First molar left

75.6 (4150.9)

70.2 (3679.1)

95.6 (4460.2)

89.1 (3942.6)

59.6 (4668.9)

57.3 (4116.3)

Maximum von Mises stress values in periimplant bone and implants of 1-piece, 2-piece, and 3-piece frameworks with axial and nonaxial loads. Stress values on implants given in parentheses.

1 Periimplant bone stress distribution under axial load on 1-piece superstructure.

2 Nonsegmented framework. Periimplant bone stress distribution around right first premolar and right first molar implants under axial load. implants placed on the right quadrant in the same positions. By contrast, stress values on the left quadrant periimplant bone at any implant location were lower than on the right side periimplant bone. This dissociation

between the left and right quadrants can be explained by the asymmetry of the superstructures and mandibular models used for this study, and by differences among implant locations. Therefore, stress distribution in implants

The Journal of Prosthetic Dentistry

and the periimplant bone of a mandibular 1-piece fixed complete denture or a fixed complete denture divided into sections cannot be predicted under mastication load. In contrast, without considering the superstructure type or force direction, the highest stress values were always found in the posterior areas of the 3 models. These results were expected, because the greatest loads were applied on posterior implants during the trial. For clinical practice, reducing other occasional force factors on posterior implants may be recommended. Similarly, higher stress rates were repeatedly observed for axial loads than for nonaxial loads in the 3 models, without regard to the superstructure type or the implant location. This result disagrees with other surveys, which found higher stress values under nonaxial loads.18,33-36 However, it agrees with a study carried out in an animal model where nonaxial forces did not adversely affect the implant integration.37 Not enough studies have been done to elucidate the influence of load inclination on periimplant bone stress values. In relation to the effect of the superstructure type, the lowest stress values, with the exception of the implants in the canine positions, for both the implants and the periimplant bone were obtained with the 3-piece superstructure model, regardless of the force direction and implant location. By contrast, the highest rates were

Alvarez-Arenal et al

-

2014

5

3 Periimplant bone stress distribution under axial load on 2-piece superstructure.

4 Superstructure divided in 2 segments. Periimplant bone stress distribution around right first molar implant under axial load.

5 Periimplant bone stress distribution under axial load on 3-piece superstructure.

obtained with the 2-piece superstructure, which may be associated with the presence of the mesial cantilever generated by the midline separation. The higher stress found in posterior implants was not consistent with the characteristic class 1 lever behavior of

Alvarez-Arenal et al

mesial cantilevers, where posterior implants are under less stress than those located in anterior areas. Nonetheless, because the mechanical analysis of 2 or more implants sharing the load in a cantilever prosthesis is complex, a strict analogy with a class 1 lever cannot be

applied. In any case, several studies have noted that cantilever partial fixed dental prostheses do not present significantly worse biologic effects or lower survival rates when compared with those without cantilevers.5-8 According to the data provided by the present study, bone tissue surrounding splinted implants in a 1-piece fixed complete denture was found to exhibit stress values between those observed for 2- and 3-piece superstructures. The fact that the parameter of mandibular deflection was not included in this study may have affected the results. In spite of differences concerning the implant position and number, load magnitude, and superstructure design, the results of this study partly agree with several studies that reported less bone stress around teeth and implants with a 1-piece fixed complete denture than with segmented superstructures.16-19 In contrast, these results do not agree with the study that described less stress during molar clenching in a fixed mandibular complete denture divided into a 3-piece superstructure than in one divided into a 2-piece superstructure.13 Other surveys have found that splinting implants in fixed partial prostheses, complete arch, or overdentures does not significantly improve implant success rates when compared with unsplinted implants.14-24 According to this, insufficient data are presently available to determine whether a 1-piece fixed complete denture is the optimum therapy for restoring an edentulous mandible. In the present study, the 3-piece superstructure was found to be the model that most reduced bone stress in the vicinity of implants at any location, except for those placed in the canine regions. This result agrees with a previous study that reported lower periimplant bone stress with a 3-piece superstructure during molar clenching and a greater inhibition of mandibular deformation than with a 2-piece superstructure.13 However, it disagrees with other surveys that found that a 1-piece fixed complete denture

6

Volume

6 Superstructure divided in 3 segments. Periimplant bone stress distribution around right first premolar implant under axial load.

transmitted less stress to the periimplant bone than 2- or 3-piece superstructures.16,17 In any case, this design offers advantages in that it inhibits jaw deformation more efficiently than the 2-piece superstructure and, when a technical or mechanical failure occurs, the repair cost is reduced.13 This study provided more detailed information about the biomechanical behavior of a 1-piece fixed complete denture and 2-piece and 3-piece superstructures. The findings indicated a clear need to further investigate this topic. The decision-making process should be based mainly on the longterm survival and complication rates of each design. This study evaluated the effect on the stress distribution within the implants and periimplant bone under axial and nonaxial load of splinting or not splinting the implants in a mandibular fixed complete denture by using a 3D finite element analysis. The finite element method has been used for more than 20 years to gain an understanding of the mechanical environment of the implant, periimplant bone, and prosthetic components in diverse situations. However, the use of mathematical models and computer simulations involves assuming several simplifications relating to material properties, geometry, and load conditions. Consequently, the obtained data do not correspond to the clinical practice results, and a qualitative

comparison between models is recommended rather than focusing on quantitative data extracted from finite element analysis. This is why the present models cannot provide absolute, realistic implant and periimplant bone stress values, but only an approach to the clinical situation. Material properties greatly influence the distribution of stress, but in agreement with most studies, all the materials in this study have been assumed to be homogeneous and linearly isotropic. Similarly, a cobalt-chromium alloy framework and feldspathic porcelain veneering were chosen for the superstructure. Perfect implant osseointegration, perfect framework abutment connection, perfect passive fit, and perfect condylar anchorage were also assumed. The load magnitude was different for each tooth, depending on its position along the mandibular alveolar process. In an attempt to imitate the mastication force variation from 1 area of the mouth to another, it ranged from a minimum of 5.12 N on the lateral incisor to a maximum of 286 N on the first molar. Nevertheless, complex mastication patterns cannot be accurately reproduced, and the clinician must also consider this as a limitation when it comes to the clinical application of the finite element analysis. The force direction was also considered. In this study, axial (vertical) loads and nonaxial loads (oblique

The Journal of Prosthetic Dentistry

-

Issue

-

loads of 6 degrees for posterior teeth and 35 degrees for anterior teeth) were applied to the prosthesis superstructure. Given that fixed complete dentures can combine straight and angled implants or abutments, these directions were specifically chosen to better simulate the biomechanical behavior of the prosthesis. Although only 3 inclinations may be a limiting factor, this may better represent common clinical situations than other angulations found in the literature, for example, 60 or even 90 degrees. Another inherent limitation of the present study is the absence of force vectors simulating the mastication muscle action. Additionally, neither the temporomandibular joints nor the resin layer were modeled in this research, a fact that may also be considered.

CONCLUSIONS Within the limitations of this 3D finite element study and in accordance with the results obtained, the following conclusions may be drawn. The 3-piece superstructure design was the most effective in reducing stress transmission to the periimplant bone. The direction of the occlusal load (axial and nonaxial) had no significant influence on periimplant bone stress values for any of the 3 models. Regardless of the division of the framework, the greatest stresses were consistently found in the posterior implants.

REFERENCES 1. 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. 2. Miyata T, Kobayashi Y, Araki H, Ohto T, Shin K. The influence of controlled occlusal overload on peri-implant tissue, part III: a histologic study in monkeys. Int J Oral Maxillofac Implants 2000;15:425-31. 3. Fu JH, Hsu YT, Wang HL. Identifying occlusal overload and how to deal with it to avoid marginal bone loss around implants. Eur J Oral Implantol 2012;5(suppl):S91-103. 4. Misch CE, Suzuki JB, Misch-Dietsh FM, Bidez MW. A positive correlation between occlusal trauma and periimplant bone loss: literature support. Implant Dent 2005;14: 108-16.

Alvarez-Arenal et al

-

2014

5. Aglietta M, Siciliano VI, Zwahlen M, Brägger U, Pjetursson BE, Lang NP, et al. A systematic review of the survival and complication rates of implant-supported fixed partial dentures with cantilever extensions under an observation period of at least 5 years. Clin Oral Implants Res 2009;5: 441-51. 6. Romeo E, Lops D, Margutti E, Ghisolfi M, Chiapasco M, Vogel G. Implant-supported fixed cantilever prostheses in partially edentulous arches: a seven-year prospective study. Clin Oral Implants Res 2003;14:303-11. 7. Romeo E, Lops D, Margutti E, Ghisolfi M, Chiapasco M, Vogel G. Long-term survival and success of oral implants in the treatment of full and partial arches: a 7-year prospective study with the ITI dental implant system. Int J Oral Maxillofac Implants 2004;19: 247-59. 8. Wennström J, Zurdo J, Karlsson S, Ekestubbe A, Grondalh K, Lindhe J. Bone level change at implant-supported fixed partial dentures with and without cantilever extension after 5 years in function. J Clin Periodontol 2004;31:1077-83. 9. Rangert B, Jemt T, Jörneus L. Forces and moments on Brånemark implants. Int J Oral Maxillofac Implants 1989;4:241-7. 10. Geng JP, Tan KB, Liu GR. Application of finite element analysis in implant dentistry: a review of literature. J Prosthet Dent 2001;85: 585-98. 11. Hobkirk JA, Schwab J. Mandibular deformation in subjects with osseointegrated implants. Int J Oral Maxillofac Implants 1991;6: 319-28. 12. English CE. Biomechanical concerns with fixed partial dentures involving implants. Implant Dent 1993;2:221-42. 13. Nokar S, Baghai Naini R. The effect of superstructure design on stress distribution in peri-implant bone during mandibular flexure. Int J Oral Maxillofac Implants 2010;25:31-7. 14. Zarone F, Apicella A, Nicolais L, Aversa R, Sorrentino R. Mandibular flexure and stress build-up in mandibular full-arch fixed prostheses supported by osseointegrated implants. Clin Oral Implants Res 2003;14: 103-14. 15. Paez CY, Barco T, Roushdy S, Andres C. Split frame implant prostheses designed to compensate for mandibular flexure: a clinical report. J Prosthet Dent 2003;89:341-3. 16. Yokoyama S, Wakabayashi N, Shiota M, Ohyama T. Stress analysis in edentulous mandibular bone supporting implant-retained 1-piece or multiple superstructures. Int J Oral Maxillofac Implants 2005;20:578-83. 17. Maezawa N, Shiota M, Kasugai S, Wakabayashi N. Three-dimensional stress analysis of tooth/implant-retained long-span fixed dentures. Int J Oral Maxillofac Implants 2007;22:710-8.

Alvarez-Arenal et al

7 18. Hauchard E, Fournier BP, Jacq R, Bouton A, Pierrisnard L, Naveau A. Splinting effect on posterior implants under various loading modes: a 3D finite element analysis. Eur J Prosthodont Restor Dent 2011;19:117-22. 19. Bergkvist G, Simonsson K, Rydberg K, Johansson F, Derand T. A finite element analysis of stress distribution in bone tissue surrounding uncoupled or splinted dental implants. Clin Implant Dent Relat Res 2008;10:40-6. 20. Stasinopoulou I, Manda M, Galanis C, Koidis P. The effect of type of restoration on the stress field developed in terminal abutments with severely reduced periodontal support and coronal structure. J Prosthet Dent 2013;110:303-12. 21. Kregzde M. A method of selecting the best implant prosthesis design option using three dimensional finite element analysis. Int J Oral Maxillofac Implants 1993;8:662-73. 22. Barão VA, Delben JA, Lima J, Cabral T, Assunção WG. Comparison of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandibleea computed tomography-based three-dimensional finite element analysis. J Biomech 2013;46:1312-20. 23. Weber HP, Sukotjo C. Does the type of implant prosthesis affect outcomes in the partially edentulous patient? Int J Oral Maxillofac Implants 2007;22(suppl):140-72. 24. Stoumpis C, Kohal RJ. To splint or not to splint oral implants in the implant-supported overdenture therapy? A systematic literature review. J Oral Rehabil 2011;38:857-69. 25. Lekholm U, Zarb GA. Patient selection and preparation. In: Bränemark PI, Zarb GA, Albreksson T, editors. Tissueintegrated prostheses: osseointegration in clinical dentistry. Chicago: Quintessence; 1985. p. 199-209. 26. Truhlar RS, Orenstein IH, Morris HF, Ochi S. Distribution of bone quality in patients receiving endosseous dental implants. J Oral Maxillofac Surg 1997;55(suppl 5):38-45. 27. Baggi L, Pastore S, Di Girolamo M, Vairo G. Implant-bone load transfer mechanisms in complete-arch prostheses supported by four implants: a three-dimensional finite element approach. J Prosthet Dent 2013;109:9-21. 28. Sevimay M, Turhan F, Kiliçarslan MA, et al. 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. 29. Suansuwan N, Swain MV. Determination of elastic properties of metal alloys and dental porcelains. J Oral Rehabil 2001;28:133-9. 30. Anusavice KJ, Coscone P. Dental casting and soldering alloys. In: Anusavice KJ, editor. Phillips’ science of dental materials. 11th ed. St Louis: Elsevier; 2003. p. 563-620.

31. Borchers L, Reichart P. Three-dimensional stress distribution around a dental implant at different stages of interface development. J Dent Res 1983;62:155-9. 32. Watanabe M, Hattori Y, Satoh C. Biological and biomechanical perspectives of normal dental occlusion. International Congress Series 2005;1284:21-7. 33. Oliveira de Almeida E, Passos Rocha E, Gonçalves Assunçao W, Chagas Freitas A Jr, Bruniera Anchieta R. Cortical bone stress distribution in mandibles with different configurations restored with prefabricated barprosthesis protocol: a three-dimensional finite-element analysis. J Prosthodont 2011;20:29-34. 34. Quian L, Todo M, Matsushita Y, Koyano K. Effects of implant diameter, insertion depth and loading angle on stress/strain fields in implant/jawbone systems: finite element analysis. Int J Oral Maxillofac Implants 2009;24:877-86. 35. Tabata LF, Assunção WG, Barão VA, Gomes EA, Delben JA, de Sousa EA, et al. Comparison of single-standing or connected implants on stress distribution in bone of mandibular overdentures: a two-dimensional finite element analysis. J Craniofac Surg 2010;21:697-702. 36. Sütpideler M, Eckert SE, Zobitz M, An KN. Finite element analysis of effect of prosthesis height, angle of force application, and implant offset on supporting bone. Int J Oral Maxillofac Implants 2004;19:819-25. 37. Celleti R, Pameijer CH, Brachetti G, Donath K, Persichetti G, Visani I. Histologic evaluation of osseointegrated implants restored in nonaxial functional occlusion with preangled abutments. Int J Periodontics Restorative Dent 1995;15:563-73. Corresponding author: Dr Angel Alvarez-Arenal Department of Prosthodontics and Occlusion School of Dentistry Calle del Catedrático Serrano s/n 33006 Oviedo SPAIN E-mail: [email protected] Acknowledgment The authors thank Dr Eng Fernando SanchezLasheras, Director, Tecniproject, who provided the computer-aided design data of the implant, periimplant bone, abutment, and framework geometry. Copyright ª 2014 by the Editorial Council for The Journal of Prosthetic Dentistry.

Should oral implants be splinted in a mandibular implant-supported fixed complete denture? A 3-dimensional-model finite element analysis.

The design of a mandibular fixed complete denture can influence periimplant bone loss. However, the design that transfers the greatest stress to the p...
2MB Sizes 0 Downloads 3 Views