Regular and platform switching: bone stress analysis varying implant type

Purpose: This study aimed to evaluate stress distribution on peri‐implant bone simulating the influence of platform switching in external and internal hexagon implants using three‐dimensional finite element analysis. Materials and Methods: Four mathematical models of a central incisor supported by an implant were created: External Regular model (ER) with 5.0 mm × 11.5 mm external hexagon implant and 5.0 mm abutment (0% abutment shifting), Internal Regular model (IR) with 4.5 mm × 11.5 mm internal hexagon implant and 4.5 mm abutment (0% abutment shifting), External Switching model (ES) with 5.0 mm × 11.5 mm external hexagon implant and 4.1 mm abutment (18% abutment shifting), and Internal Switching model (IS) with 4.5 mm × 11.5 mm internal hexagon implant and 3.8 mm abutment (15% abutment shifting). The models were created by SolidWorks software. The numerical analysis was performed using ANSYS Workbench. Oblique forces (100 N) were applied to the palatal surface of the central incisor. The maximum (σ_max) and minimum (σ_min) principal stress, equivalent von Mises stress (σ_vM), and maximum principal elastic strain (ε_max) values were evaluated for the cortical and trabecular bone. Results: For cortical bone, the highest stress values (σ_max and σ_vm) (MPa) were observed in IR (87.4 and 82.3), followed by IS (83.3 and 72.4), ER (82 and 65.1), and ES (56.7 and 51.6). For ε_max, IR showed the highest stress (5.46e‐003), followed by IS (5.23e‐003), ER (5.22e‐003), and ES (3.67e‐003). For the trabecular bone, the highest stress values (σ_max) (MPa) were observed in ER (12.5), followed by IS (12), ES (11.9), and IR (4.95). For σ_vM, the highest stress values (MPa) were observed in IS (9.65), followed by ER (9.3), ES (8.61), and IR (5.62). For ε_max, ER showed the highest stress (5.5e‐003), followed by ES (5.43e‐003), IS (3.75e‐003), and IR (3.15e‐003). Conclusion: The influence of platform switching was more evident for cortical bone than for trabecular bone, mainly for the external hexagon implants. In addition, the external hexagon implants showed less stress concentration in the regular and switching platforms in comparison to the internal hexagon implants.     

眶部种植体长度对骨界面应力影响的三维有限元研究

目的 探讨不同长度的眶部种植体对骨界面应力分布的影响。方法 建立直径3.75 mm,长度分别为3、4、6、10 mm的眶部种植体-颅颌面骨三维有限元模型,分别给予沿种植体轴向和与轴向成45°的载荷,载荷大小20 N,记录两种方向载荷下种植体及骨界面的Von-Mises应力峰值和位移峰值,分析其应力分布。结果 施加沿种植体轴向载荷时,种植体周围应力集中于根部,种植体受力大于骨面;施加与轴向成45°载荷时,应力集中于种植体颈部与第一螺纹之间,种植体受力大于骨面。施加两个方向的载荷时,3 mm种植体的应力峰值明显大于其他长度种植体,而位移峰值无明显变化。在相同长度下,施加沿种植体轴向载荷时的应力峰值及位移峰值均明显低于与轴向成45°载荷时,载荷方式对界面应力分布有明显的影响。结论 临床上尽量选择4 mm以上的眶部种植体;应用3 mm种植体时,应选择骨密质较厚的区域植入。     

Effect of dental implant cross-sectional design on cortical bone structure using finite element analysis

Purpose: This finite element analysis investigation evaluated the effect of different implant cross‐sectional designs on bone stress levels under different loading patterns. Materials and Methods: Finite element analysis program was used to construct four different three‐dimensional models describing 4 × 10‐mm implants in blocks of cortical and trabecular bone. A 5‐mm‐long abutment was modeled above each implant. The implant in model 1 was unthreaded, while in model 2 the implant was circularly threaded. The third implant in model 3 had the cross‐sectional shape as a 16‐sided star‐shaped design. The implant in model 4 was constructed unthreaded, with a diameter of 4.5 mm. Vertical and horizontal loads of 100 N each were applied on the top middle node of each implant assembly. All nodes at the bottom surface of the bone models were restrained. Results: By comparing models 1, 2, and 3, the lowest bone stress values under vertical and horizontal forces were observed around the unthreaded implant in model 1 (8.92 and 94.52 MPa, respectively). The highest stress value under vertical loading was shown around the threaded implant in model 2 (10.07 MPa), whereas the highest stress value under horizontal loading was observed around the star‐shaped implant in model 3 (108.40 MPa). Model 4, with a wider unthreaded design, had stress values under vertical and horizontal loading of 7.32 and 71.35 MPa, respectively. Conclusions: It was concluded that the unthreaded implant design produced the least bone stress. An increase in implant diameter could produce marked reduction in stress value in the bone around the neck of the implant.     

Damping characteristics of bone‐to‐implant interface; A clinical study with the Periotest® device.

The Periotest® device was used to evaluate the damping characteristics of different bone‐to‐implant interfaces of Brånemark implants. Implant and abutment lengths were found to have a significant influence on Periotest value (PTV). There was no statistical difference between PTVs of implants located in the anterior and posterior areas of the same jaw at abutment connection. No differences were found between PTVs of standard and self‐tapping implants. PTVs at abutment connection were highly influenced by the bone quality. The contact with two corticals, one at each extremity of the implant, was of a greater influence in the maxillary than in the mandibular jaw, indicating a firmer anchorage between the bicortical implants and the surrounding bone. A proaressive decrease of PTVs over time was observed, significant up to 5 years of loading.     

��ͬ����ת��̨��ƶ���ֲ���Ӧ���ֲ�Ӱ�����ά����Ԫ����

??Objective    To compare the stress distribution and the stress peak of different anti-rotation design of the implant abutment and to provide reference for optimizing the structure design and clinical application of the implant. Methods    According and to Korea Dentium system??three-dimensional finite element analysis model of triangle??hexagon and octagon anti-rotation abutments were established by Solidworks. The Von Mises stress distribution and stress peak of implant??superstructures and surrounding bone tissue of three models under vertical loading and 45° inclined loading were analyzed by ANSYS Workbench14.0 finite element analysis software. Results    Under the condition of vertical loading??the mechanical stress of implants??connecting screw and surrounding tissues was small. With the increasing angles of abutment??the stress of implants appeared an increasing trend??the stress of connecting screws appeared a decreasing trend and the stress of cortical bone and cancellous bone had little difference. The stress of hexagon and octagon abutment models was better distributed??and the stress peak of hexagon abutment model was smaller. Under the condition of 45° inclined loading??the mechanical stress of each part was greater??the stress of implants and abutments appeared an increasing trend??and with the increasing angles of abutment??the stress of connecting screw appeared a decreasing trend and the stress of cortical bone and cancellous bone had little difference. The results were similar with vertical loadings. Conclusion            The triangle and hexagon abutment design may reduce the mechanical stress of implants??abutments and surrounding bone tissue??octagon abutment design may reduce the stress of connecting screws??the stress distribution of hexagon abutments is better.     

Selection of the distraction implant length with improved biomechanical properties by three‐dimensional finite element analysis

Summary In this study, the distraction length of distraction implant was set as input variable which ranged from 2 to 10 mm. The effect of distraction length on the maximum Von Mises stress in the jaw bones and the implant were evaluated by a finite element method. The results showed that under axial load, the maximum equivalent stresses in cortical bone, cancellous bone, and distraction screw decreased by 5·8%, 8·6%, and 11·0%, respectively, with the changing of distraction length, and under buccolingual load those decreased by 0·3%, 18·0%, and 13·0%, respectively. The data indicate that cancellous bone is more sensitive to distraction length than the cortical bone. Under both loads, the central distraction screw was subjected to the stress concentration and more easily damaged by buccolingual force than by axial force. Distraction implant with distraction length exceeding 8 mm showed relatively better biomechanical behaviour.     

Finite element study on the effect of abutment length and material on implant bone interface against dynamic loading

PURPOSE

Finite element study on the effect of abutment length and material on implant bone interface against dynamic loading.

MATERIALS AND METHODS

Two dimensional finite element models of cylinderical implant, abutments and bone made by titanium or polyoxymethylene were simulated with the aid of Marc/Mentat software. Each model represented bone, implant and titanium or polyoxymethylene abutment. Model 1: Implant with 3 mm titanium abutment, Model 2: Implant with 2 mm polyoxymethylene resilient material abutment, Model 3: Implant with 3 mm polyoxymethylene resilient material abutment and Model 4: Implant with 4 mm polyoxymethylene resilient material abutment. A vertical load of 11 N was applied with a frequency of 2 cycles/sec. The stress distribution pattern and displacement at the junction of cortical bone and implant was recorded.

RESULTS

When Model 2, 3 and 4 are compared with Model 1, they showed narrowing of stress distribution pattern in the cortical bone as the height of the polyoxymethylene resilient material abutment increases. Model 2, 3 and 4 showed slightly less but similar displacement when compared to Model 1.

CONCLUSION

Within the limitation of this study, we conclude that introduction of different height resilient material abutment with different heights i.e. 2 mm, 3 mm and 4 mm polyoxymethylene, does not bring about significant change in stress distribution pattern and displacement as compared to 3 mm Ti abutment. Clinically, with the application of resilient material abutment there is no significant change in stress distribution around implant-bone interface.     

Influence of implant design and bone quality on stress/strain distribution in bone around implants: a 3-dimensional finite element analysis

PURPOSE: A 3-dimensional finite element analysis was performed to evaluate the influence of implant type and length, as well as that of bone quality, on the stress/strain in bone and implant. MATERIALS AND METHODS: Two types (screw and cylinder) and 4 lengths (9.2, 10.8, 12.4, and 14.0 mm) of titanium implants were buried in 4 types of bone modeled by varying the elastic modulus for cancellous bone. Axial and buccolingual forces were applied to the occlusal node at the center of the abutment. RESULTS: Regardless of load direction, maximum equivalent stress/strain in bone increased with a decrease in cancellous bone density. Under axial load, especially in the low-density bone models, maximum equivalent strain in cancellous bone was lower with the screw-type implant than with the cylinder-type implant. It was also lower with the longer implants than with the shorter implants. Under buccolingual load, equivalent stress/strain was influenced mainly by bone density. DISCUSSION: This study confirms the importance of bone quality and its presurgical diagnosis for implant long-term prognosis. Implant length and type can also influence bone strain, especially in low-density bone. CONCLUSIONS: The results of this study suggest that cancellous bone of higher rather than lower density might ensure a better biomechanical environment for implants. Moreover, longer screw-type implants could be a better choice in a jaw with cancellous bone of low density.     

One-Year Prospective Evaluation of the Early Loading of Unsplinted Conical Brånemark Fixtures with Mandibular Overdentures Immediately following Surgery

Background: Prospective evaluation of the early loading of unsplinted Branemark implants with mandibular over‐dentures opposing conventional dentures is not evident in the implant‐related literature. Purpose: To clinically evaluate progressive and early loading of 20 unsplinted conical Brånemark implants in edentulous mandibles with overdentures. Materials and Methods: Ten edentulous patients all had two conical Brånemark implants placed in the anterior mandible with mandatory primary stability with bicortical anchorage. Ball abutment connection was performed simultaneously. Previously constructed conventional mandibular dentures were temporarily relined with tissue conditioner postoperatively and worn with moderation for the first 2 weeks to allow progressive loading. Early loading of the implants followed after 2 weeks, with inclusion of the respective matrices in the mandibular dentures, using a definitive reline procedure. Results: All patients successfully functioned with their mandibular implant overdentures from 2 to 52 weeks postoperatively. Mean marginal bone loss was within established criteria for success:0.22 mm (SD = 0.48 mm) mesially and 0.30 mm (SD = 0.39 mm) distally on the conical implants. Mobility tests using the Periotest instrument became more negative, although not at statistically significant levels. Difficulties in the management of the peri‐implant mucosa between surgery and loading at 2 weeks were observed in 40% of the patients. Conclusions: These preliminary 1‐year results show that successful early loading of unsplinted conical Brånemark implants with mandibular overdentures is possible.     

The biomechanical analysis of relative position between implant and alveolar bone: finite element method

Background: The purpose of this study is to analyze biomechanical interactions in the alveolar bone surrounding implants with smaller‐diameter abutments by changing position of the fixture–abutment interface, loading direction, and thickness of cortical bone using the finite element method. Methods: Twenty different finite element models including four types of cortical bone thickness (0.5, 1, 1.5, and 2 mm) and five implant positions relative to bone crest (subcrestal 1, implant shoulder 1 mm below bone crest; subcrestal 0.5, implant shoulder 0.5 mm below bone crest; at crestal implant shoulder even with bone crest; supracrestal 0.5, implant shoulder 0.5 mm above bone crest; and supracrestal 1, implant shoulder 1 mm above bone crest) were analyzed. All models were simulated under two different loading angles (0 and 45 degrees) relative to the long axis of the implant, respectively. The three factors of implant position, loading type, and thickness of cortical bone were computed for all models. Results: The results revealed that loading type and implant position were the main factors affecting the stress distribution in bone. The stress values of implants in the supracrestal 1 position were higher than all other implant positions. Additionally, compared with models under axial load, the stress values of models under off‐axis load increased significantly. Conclusions: Both loading type and implant position were crucial for stress distribution in bone. The supracrestal 1 implant position may not be ideal to avoid overloading the alveolar bone surrounding implants.     

平台转换种植体周围应力分布的三维有限元分析

目的:分析平台转换种植体周围的力学分布特点。方法:利用CATIA画图软件,建立种植体支持的上颌第一前磨牙三维模型,分析垂直向和斜向加载条件下平齐对接(PM)和平台转换(PS)种植体周围的应力分布差异;比较不同材料基台平台转换冠修复后种植体周围的应力分布差异。结果:①PS型种植体在垂直加载和斜向加载时种植体周围骨组织内最大von Mises应力值均较PM型小。②不同材料基台种植体周围应力分布云图相似,应力均集中在种植体颈部。结论:①PS种植体周围骨组织最大应力值较PM种植体小,但基台、中央螺丝、种植体的应力增大。②斜向加载较垂直向加载种植体周围应力值大大增加,特别是基台及种植体部位较为明显。③基台材料对种植体周围应力值无明显影响。     

One-stage operative procedure using two different implant systems: a prospective study on implant overdentures in the edentulous mandible

Background: Evidence‐based reports are needed to support the application of a one‐stage surgical protocol for unsplinted implants supporting mandibular overdentures. Purpose: To examine the feasibility and success of using two different dental implant systems (originally designed for two‐stage operative technique) using a one‐stage operative procedure in patients being rehabilitated with implant mandibular overdentures. Materials and Methods: The study sample involved 24 edentulous subjects (aged 55–80 yr) randomly allocated to two different implant systems, one with a machined titanium implant surface (Steri‐Oss, Nobel Biocare, Göteborg, Sweden) and the other with a roughened titanium surface (Southern Implants, Ltd., Irene, South Africa). Two unsplinted implants to support implant overdentures were placed in the anterior mandible of all patients, using a standardized one‐stage surgical and prosthodontic procedure. Primary stability and bicortical anchorage of the implants was mandatory before healing abutments were connected at the time of implant placement. Implant overdentures and their respective matrices were inserted following a standard 12‐week healing period. Data relating to mobility tests, radiographs, and peri‐implant parameters were documented at 12, 16, and 52 weeks after surgery. Results: A success rate of 95.8% for the Steri‐Oss and 100% for the Southern Implants was found, without any statistically significant differences in the marginal bone loss. Significant changes in Periotest values were observed for both types between 12 and 52 weeks (p <.001). Minor changes were observed in the peri‐implant parameters evaluated. Conclusions: These preliminary findings show a successful application of this one‐stage approach for unsplinted implants supporting mandibular overdentures with Steri‐Oss and Southern Implant Systems.     

Finite element analysis of an osseointegrated stepped screw dental implant

An osseointegrated stepped screw dental implant was evaluated using 2-dimensional finite element analysis (FEA). The implant was modeled in a cross section of the posterior human mandible digitized from a computed tomography (CT) generated patient data set. A 15-mm regular platform (RP) Branemark implant with equivalent length and neck diameter was used as a control. The study was performed under a number of clinically relevant parameters: loading at the top of the transmucosal abutment in vertical, horizontal, and 45 degrees oblique 3 orientations. Elastic moduli of the mandible varied from a normal cortical bone level (13.4 GPa) to a trabecular bone level (1.37 GPa). The study indicated that an oblique load and elastic moduli of the cortical bone are important parameters to the implant design optimization. Compared with the cylindrical screw implant, the maximum von Mises stress of the stepped screw implant model was 17.9% lower in the trabecular bone-implant area. The study also showed that the stepped screw implant is suitable for the cortical bone modulus from 10 to 13.4 GPa, which is not necessarily as strict as the Branemark implant, for which a minimum 13.4 GPa cortical bone modulus is recommended.     

双皮层骨种植影响牙种植体稳定性的有限元固有频率分析

目的:用有限元方法研究双皮层骨种植对牙种植体初期稳定性的影响。方法:建立牙种植体、局部下颌骨块三维有限元模型,利用ABAQUS有限元软件,分析双皮层骨种植对种植体颊舌向、轴向一阶振动固有频率的影响。结果:在模拟的3种不同骨质类型中,双皮层骨种植均可提高种植体颊舌向、轴向振动的固有频率值,但颊舌向频率的增加有限,最高增加了13. 77%,而轴向频率值最大增加了一倍以上。结论:双皮层骨种植主要增加种植体轴向稳定性,对种植体水平向稳定性的增加有限。     

Tension More种植体骨界面的光弹应力分析

目的 研究不同锥度设计的Tension More（TM）种植体对种植体骨界面应力分布的影响。方法 医用纯钛制作5组种植体,分别为圆柱状螺纹种植体、上1/3 TM种植体（锥度长度为3 mm）、中1/2 TM种植体（锥度长度为5 mm）、下1/3 TM种植体（锥度长度为7 mm）、全长变化TM种植体（锥度长度为10 mm）。每组种植体各自包埋于由松质骨及1 mm皮质骨构成的复合光弹模型中,共建立5个复合光弹模型。每一模型先后分别予以垂直及斜向（45°）静态加载力。利用光弹应力分析法比较5组种植体骨界面的生物力学特征。结果 垂直加载下,上1/3 TM种植体、中1/2 TM种植体、下1/3 TM种植体比圆柱状螺纹种植体在皮质骨区及松质骨区的局部应力集中小;斜向加载下,4组TM种植体皮质骨区局部应力集中均低于圆柱状螺纹种植体。无论在垂直、斜向加载下,上1/3 TM种植体皮质骨区局部应力集中均最小。结论 合理锥度设计的TM种植体周围皮质骨、松质骨应力分布均匀合理,在不同载荷条件下,上1/3 TM种植体骨界面生物力学表现最优。     

Histopathologic observations on late oral implant failures

Background: Despite good success rates of osseointegrated oral implants, failures do occur. To minimize losses, failure mechanisms should be elucidated. Purpose: This study sought to describe the morphology of tissues surrounding late failed Brånemark implants in relation to their clinical and radiographic findings to acquire a better understanding of the etiologic factors. Material and Methods: Ten failed implants and their surrounding tissues were consecutively retrieved from nine patients after prosthesis placement (late losses). On radiographs, a radiolucent line was visible around nine clinically mobile implants. Tightening of the abutment screw evoked pain at seven mobile implants. Clinically, no other visual inflammatory sign or symptom was manifest. A fistula originated from one stable implant, surrounded on radiographs by a diffuse bone rarefaction. Retrieved implants were electrochemically dissolved. Intact tissue‐implant thin (1 μm) and ultrathin (70–80 nm) sections were analyzed with light and transmission electron microscopy. Results: Peri‐implant marginal tissues displayed moderate inflammatory infiltrates located adjacent to and beneath the junctional epithelium. One patient affected by oral lichen planus displayed an intense lymphocyte/plasma cell‐dominated immune reaction. Deep peri‐implant tissues surrounding mobile implants consisted of a dense, fibrous tissue capsule with minimal inflammation. Epithelial downgrowth was observed around four implants. Small areas of nonmineralized bone in contact with the implant were noticed in the apical portion of two implants. One implant was almost entirely colonized by bacterial plaque with the exception of its apical portion, where bone‐implant contact was observed. The stable implant was characterized by bone‐implant contact. Conclusion: Altogether clinical, radiographic, and histologic findings indicated that two major etiologic factors might have been implicated in the failure process of the investigated implants: excessive occlusal load in relation to the bone‐supporting capacity and, in two cases, infection.     

Influences of internal tapered abutment designs on bone stresses around a dental implant: three-dimensional finite element method with statistical evaluation

Background: The aim of this study is to determine the effects of various designs of internal tapered abutment joints on the stress induced in peri‐implant crestal bone by using the three‐dimensional finite element method and statistical analyses. Methods: Thirty‐six models with various internal tapered abutment–implant interface designs including different abutment diameters (3.0, 3.5, and 4.0 mm), connection depths (4, 6, and 8 mm), and tapers (2°, 4°, 6°, and 8°) were constructed. A force of 170 N was applied to the top surface of the abutment either vertically or 45° obliquely. The maximum von Mises bone‐stress values in the crestal bone surrounding the implant were statistically analyzed using analysis of variance. In addition, patterns of bone stress around the implant were examined. Results: The results demonstrate that a smaller abutment diameter and a longer abutment connection significantly reduced the bone stresses (P <0.0001) in vertical and oblique loading conditions. Moreover, when the tapered abutment–implant interfaced connection was more parallel, bone stresses under vertical loading were less (P = 0.0002), whereas the abutment taper did not show significant effects on bone stresses under oblique loading (P = 0.83). Bone stresses were mainly influenced by the abutment diameter, followed by the abutment connection depth and the abutment taper. Conclusion: For an internal tapered abutment design, it was suggested that a narrower and deeper abutment–implant interface produced the biomechanical advantage of reducing the stress concentration in the crestal region around an implant.     

Displacement of Dental Implants in Trabecular Bone under a Static Lateral Load in Fresh Bovine Bone

Aim: The study aims to provide objective data for the displacement of titanium screw implants in trabecular bone specimens. One hundred Semados implants (Bego, Bremen, Germany) were inserted in bovine type IV bone specimens. All implants had a diameter of 3.75 mm; 50 implants had a length of 8.5 mm and 50 implants had a length of 15 mm. Insertion torque was determined at intervals of 10, 20, and 30 Ncm. Implants were loaded horizontally with 10, 20, and 30 N for 2 seconds. An indicator strip was attached to the implant abutment to allow direct observation of implant movement relative to the bone surface. Horizontal displacement was assessed with an accuracy of measurement of 10 µm. Seven implants got lost by visible loosening. Degree of displacement was subject to evaluation with all others. Those implants showed a mean displacement of 59 µm for 10 N (n = 100), 173 µm for 20 N (n = 99), and 211 µm for 30 N (n = 93). The mean displacement of 15‐mm implants (16, 37, 51 µm) was significantly lower compared with 8.5‐mm implants (103, 311, 396 µm) corresponding to 10, 20, and 30 N as lateral loads. Conclusions: Displacement of screw implants in trabecular bone can be detected and visualized using commercially available endoscopes with a high magnification. A lateral load of 20 N indicates a mean displacement of over 100 µm and therefore results in a critical displacement.     

Effects of the Implant Design on Peri‐Implant Bone Stress and Abutment Micromovement: Three‐Dimensional Finite Element Analysis of Original Computer‐Aided Design Models

Background: Occlusal overloading causes peri‐implant bone resorption. Previous studies examined stress distribution in alveolar bone around commercial implants using three‐dimensional (3D) finite element analysis. However, the commercial implants contained some different designs. The purpose of this study is to reveal the effect of the target design on peri‐implant bone stress and abutment micromovement. Methods: Six 3D implant models were created for different implant–abutment joints: 1) internal joint model (IM); 2) external joint model (EM); 3) straight abutment (SA) shape; 4) tapered abutment (TA) shapes; 5) platform switching (PS) in the IM; and 6) modified TA neck design (reverse conical neck [RN]). A static load of 100 N was applied to the basal ridge surface of the abutment at a 45‐degree oblique angle to the long axis of the implant. Both stress distribution in peri‐implant bone and abutment micromovement in the SA and TA models were analyzed. Results: Compressive stress concentrated on labial cortical bone and tensile stress on the palatal side in the EM and on the labial side in the IM. There was no difference in maximum principal stress distribution for SA and TA models. Tensile stress concentration was not apparent on labial cortical bone in the PS model (versus IM). Maximum principal stress concentrated more on peri‐implant bone in the RN than in the TA model. The TA model exhibited less abutment micromovement than the SA model. Conclusion: This study reveals the effects of the design of specific components on peri‐implant bone stress and abutment displacement after implant‐supported single restoration in the anterior maxilla.     

Immediate functional loading of single-tooth TIO2 grit-blasted implant restorations: a controlled prospective study in a porcine model. Part I: Clinical outcome

Background: Although favorable integration occurs with immediately loaded implants, the relationship between implant outcome, levels of occlusion, and diet requires optimization. Purpose: Pertubating load on single implant restorations immediately after placement by a hard food diet will increase the strains at the bone‐implant interface, increasing the risk for failure. Materials and Methods: Forty‐eight implants replaced the first and third mandibular premolars in 12 pigs, allocated into two groups based on soft‐ and hard‐diet feeding. Cylindrical and tapered implants replaced the first and third premolars, respectively. Each animal received at random four different masticatory loading conditions (group 1 control]: implant with either a cover screw or a healing abutment, and group 2 test]: implant with a crown either with or without occlusal contacts). Results: Thirteen implants out of 44 failed in 11 animals (one with a cover screw, one with a healing abutment, three with nonocclusal, and eight with occlusal restorations). The failure rate of restored implants (either in occlusion or not) was significantly higher in the third premolar sites (p=.007), although diet had no significant effect (p=.421). Conclusions: While diet had no effect on the failure pattern of immediately loaded single implants, the position and type of load under the masticatory mode were significant. Immediately loaded implants both in and out of occlusion were less successful than the controls, and this is probably attributed to detrimental strain induced on the bone‐implant interface.