A Comparative Evaluation of Stress Distribution Around Different Widths of Implant and Bony Interface in Function During Axial and Non-axial Loading: A Finite Element Analysis.

OBJECTIVE: The study employed three-dimensional (3D) finite element analysis (FEA) and examined how implant diameters affect stress distribution across the implant-bone contact and how stress transmission through this interface changes during axial and non-axial loading. MATERIALS AND METHODS: A 3D mandibular model was created using cone beam CT of a patient with implants inserted into the first mandible molar. Nobel Biocare implants (Nobel Biocare, Switzerland) with specific dimensions of 3.5 mm, 4.3 mm, 5.0 mm, and 6.0 mm were chosen. Models were created in CATIAV5R19 (Dassault Systemes, France) from threaded titanium implant dimensions. Implants were finite element-modeled utilizing ANSYS Workbench v11.0 (Ansys, Inc, Pennsylvania, USA). The analysis involved applying 100 N axial, 50 N buccolingual, and 50 N mesiodistal loads. RESULTS: In a lower first molar bone segment, the implant top surface was loaded in 100 N axial, 50 N buccolingual, and 50 N mesiodistal orientations. The cortical bone proximal to the implant neck had the most von Mises stress, regardless of model or stress scenario. In Model I cortical bone, maximal stress was centered at the implant neck. Most stress was on lingual bone plates, lesser on buccal, and least on mesial and distal. Less than half of the implant stress was transmitted to the cortical bone. The stress transferred from the implant to the cortical bone in Model II was less than half of the implant stress. The same was true for Models III and IV. In Model I cancellous bone, stress was concentrated in the implant's coronal half and minimal in the apical half. CONCLUSION: The stress patterns under axial loading were distributed favorably. Therefore, it can be inferred that an augmentation in the diameter of the implant enhances the even distribution of stress at the interface between the bone and the implant by offering a larger surface area for the dispersion of stress. Furthermore, it was determined that applying force along an implant's axis was a beneficial loading direction and did not negatively impact its lifespan.

[Constructive complications in dental implantology (clinical case series)]. / Konstruktivnye oslozhneniya v dental'noi implantologii (na primere klinicheskikh sluchaev).

The aim the study. Analyze errors in planning orthopedic treatment using dental implants using the example of clinical cases. MATERIALS AND METHODS: Two patients are presented who applied for a consultation at the orthopedic and surgical department of the Federal State Budgetary Institution National Medical Research Center Central Research Institute of Chronic and Peripheral Surgery of the Russian Ministry of Health regarding a fracture of a previously installed orthopedic structure on an implant. For diagnostic purposes, computed tomography was performed to determine the condition of the implants and teeth of the upper and lower jaws. RESULTS: The patients were found to have: a fracture of an implant 4.0*10 with a single orthopedic structure in the area of tooth 4.6 (the patient did not undergo restoration of the missing tooth 4.7 in the presence of an antagonist), a fracture of small diameter implants (3.5*9) in the area of 3.6, 3.7, prosthetic combined orthopedic crowns. CONCLUSIONS: During surgical and orthopedic treatment of patients, it is necessary to strictly follow the instructions developed by the manufacturer of dental implants and the STaR recommendations.

Effects of diameters of implant and abutment screw on stress distribution within dental implant and alveolar bone: A three-dimensional finite element analysis.

Background/purpose: Few studies have investigated the effects of abutment screw diameter in the stress of dental implants and alveolar bones under occlusal forces. In this study, we investigated how variations in implant diameter, abutment screw diameter, and bone condition affect stresses in the abutment screw, implant, and surrounding bone. Materials and methods: Three-dimensional finite element (FE) models were fabricated for dental implants with external hex-type abutments measuring 4 and 5 mm in diameter. The models also included abutment screws measuring 2.0 and 2.5 mm in diameter. Each implant model was integrated with the mandibular bone comprising the cortical bone and four types of cancellous bone. In total, 12 finite element models were generated, subjected to three different occlusal forces, and analyzed using FE software to investigate the stress distribution of dental implant and alveolar bone. Results: Wider implants demonstrated lower stresses in implant and bone compared with standard-diameter implants. The quality of cancellous bone has a minimal impact on the stress values of the implant, abutment screw, and cortical bone. Regardless of occlusal arrangement or quality of cancellous bone, a consistent pattern emerged: larger abutment screw diameters led to increased stress levels on the screws, while the stress levels in both cortical and cancellous bone showed comparatively minor fluctuations. Conclusion: Wider implants tend to have better stress distribution than standard-diameter implants. The potential advantage of augmenting the abutment screw diameter is unfavorable. It may result in elevated stresses in the implant system.

Zirconia dental implants; the relationship between design and clinical outcome: A systematic review.

OBJECTIVE: To evaluate the clinical outcome of different designs of zirconia dental implants. DATA: This systematic review adhered to the PRISMA checklist and followed the PICO framework. The protocol is registered in PROSPERO (CRD42022337228). SOURCES: The search was conducted in March 2023 through four databases (PubMed, Web of Science, Cochrane Library, and Google Scholar) along with a search of references in the related reviews. Three authors reviewed on title, and abstract level and analysed the risk of bias, and all authors reviewed on a full-text level. STUDY SELECTION: Clinical studies excluding case reports for patients treated with different designs of zirconia dental implants were included. From a total of 2728 titles, 71 full-text studies were screened, and 27 studies were included to assess the risk of bias (ROBINS-I tool) and data extraction. After quality assessment, four studies were included, and the remaining 23 excluded studies were narratively described. RESULT: The included prospective studies with moderate risk of bias reported success and survival rates of one-piece implants that ranged between 95 and 98.4 % with no difference between different lengths and diameters. The acid-etched roughened surface showed higher clinical outcomes compared to other surface roughness designs. CONCLUSION: Promising 5-year clinical outcomes were found for one-piece zirconia implants with no difference between different diameters and lengths. Concerning surface roughness, better outcomes were found when using the acid-etched implant surface. However, due to the limited available studies, further high-quality clinical studies comparing zirconia one-piece and two-piece implants with different diameters, lengths, and surface roughness are needed. CLINICAL SIGNIFICANCE: Based on this systematic review, under suitable clinical situations, the one-piece zirconia implants with diameters of 4.0 mm, 4.5 mm, or 5.5 mm and lengths of 8 mm, 10 mm, 12 mm, or 14 mm have similar promising clinical outcomes. Additionally, the acid-etched roughened implant surface may be preferable.

Biomechanical behavior of implants with different diameters in relation to simulated bone loss- an in vitro study.

OBJECTIVES: Bone resorption around implants could influence the resistance of the implant abutment complex (IAC). The present in vitro study aimed to assess the stability to static fatigue of implants presenting different levels of bone losses and diameters. MATERIALS AND METHODS: Ninety implants with an internal conical connection with 3 different implant diameters (3.3 mm (I33), 3.8 mm (I38), and 4.3 mm (I43)) and 3 simulated bone loss settings (1.5 mm (I_15), 3.0 mm (I_30), and 4.5 mm (I_45) (n = 10)) were embedded and standard abutments were mounted. All specimens were artificially aged (1,200,000 cycles, 50 N, simultaneous thermocycling) and underwent subsequently load-to-fracture test. For statistical analysis, Kolmogorov-Smirnov test, Kruskal-Wallis test, and Mann-Whitney U test (p < 0.05) were applied. RESULTS: All test specimens withstood the artificial aging without damage. The mean failure values were 382.1 (± 59.2) N (I3315), 347.0 (± 35.7) N (I3330), 315.9 N (± 30.9) (I3345), 531.4 (± 36.2) N (I3815), 514.5 (± 40.8) N (I3830), 477.9 (± 26.3) N (I3845), 710.1 (± 38.2) N (I4315), 697.9 (± 65.2) N (I4330), and 662.2 N (± 45.9) (I4345). The stability of the IACs decreased in all groups when bone loss inclined. Merely, the failure load values did not significantly differ among subgroups of I43. CONCLUSIONS: Larger implant diameters and minor circular bone loss around the implant lead to a higher stability of the IAC. The smaller the implant diameter was, the more the stability was affected by the circumferential bone level. CLINICAL RELEVANCE: Preserving crestal bone level is important to ensure biomechanical sustainability at implant systems with a conical interface. It seems sensible to take the effect of eventual bone loss around implants into account during implant planning processes and restorative considerations.

How does dental implant macrogeometry affect primary implant stability? A narrative review.

PURPOSE: The macrogeometry of a dental implant plays a decisive role in its primary stability. A larger diameter, a conical shape, and a roughened surface increase the contact area of the implant with the surrounding bone and thus improve primary stability. This is considered the basis for successful implant osseointegration that different factors, such as implant design, can influence. This narrative review aims to critically review macro-geometric features affecting the primary stability of dental implants. METHODS: For this review, a comprehensive literature search and review of relevant studies was conducted based on formulating a research question, searching the literature using keywords and electronic databases such as PubMed, Embase, and Cochrane Library to search for relevant studies. These studies were screened and selected, the study quality was assessed, data were extracted, the results were summarized, and conclusions were drawn. RESULTS: The macrogeometry of a dental implant includes its surface characteristics, size, and shape, all of which play a critical role in its primary stability. At the time of placement, the initial stability of an implant is determined by its contact area with the surrounding bone. Larger diameter and a conical shape of an implant result in a larger contact area and better primary stability. But the linear relationship between implant length and primary stability ends at 12 mm. CONCLUSIONS: Several factors must be considered when choosing the ideal implant geometry, including local factors such as the condition of the bone and soft tissues at the implant site and systemic and patient-specific factors such as osteoporosis, diabetes, or autoimmune diseases. These factors can affect the success of the implant procedure and the long-term stability of an implant. By considering these factors, the surgeon can ensure the greatest possible therapeutic success and minimize the risk of implant failure.

Is Nail-Canal Diameter Discordance a Risk Factor for the Excessive Sliding of Cephalomedullary Nails in Geriatric Intertrochanteric Fracture Surgery?

Background and Objectives:: There were limited studies which investigated nail diameter as a predictor for cephalomedullary nail (CMN) failure in intertrochanteric fracture (ITF). We aimed to evaluate the surgical outcomes of CMN in fragility ITF following nail-canal (N-C) diameter discordance. Materials and Methods: From November 2010 to March 2022, we retrospectively reviewed 120 consecutive patients who underwent CMN surgeries due to fragility ITF. We included patients with acceptable reduction and a tip-apex distance ≤ 25 mm. The N-C diameter differences both in anterior-posterior (AP) and lateral-view X-rays were measured, and we compared the number of excessive sliding instances and the rate of implant failure between the N-C concordance (≤3 mm) and discordance (>3 mm) group. Simple linear regression was used to determine the strength of the relationship between the N-C difference and sliding distance. Results: The sliding distance showed no differences between the groups in the AP (3.6 vs. 3.3 mm, p = 0.75) and lateral view (3.5 vs. 3.4 mm, p = 0.91). For analyses in the AP view, the AP-concordance and AP-discordance groups had 14 (25%) and 14 patients (22%) with a sliding distance of >5 mm (p = 0.69), while treatment failure occurred in 3 (5%) and 3 (3%) patients, respectively (p = 0.66). For analyses in the lateral view, the lat-concordance and lat-discordance groups had 8 (27%) and 20 patients (22%) with a sliding distance of >5 mm (p = 0.62), while treatment failure occurred in 1 (3%) and 4 (4%) patients, respectively (p = 1.00). Linear regression analyses showed that the N-C difference in either views was not a significant predictor of sliding distance in both the AP (R2 = 0.002, p = 0.60) and lateral views (R2 = 0.007, p = 0.35). Conclusions: If appropriate fracture reduction and fixation are achieved, the N-C discordance of short CMN does not affect treatment outcomes in ITF.

Impact of Implant Diameter on the Early Survival Rate of Dental Implants in the Saudi Population: A One-Year Retrospective Study.

Introduction The use of dental implants provides a revolutionary solution to the problem of missing teeth in the oral cavity. The aim of this study was to assess the early implant survival rate in relation to implant diameter and site of placement. Methods The data were collected from 186 patients treated between January 2019 and June 2021. All the implants were evaluated and restored after three months of implant placement. The early implant survival was calculated for different implant diameters with the odds ratio (OR). Results A total of 373 implants were placed. Implants were placed in the following areas: upper posterior area (UPA), n = 123, upper anterior area (UAA), n = 49, lower posterior area (LPA), n = 184, and lower anterior area (LAA), n = 17. Implants of the following diameters were placed: 3.5 mm (n = 129), 4.3 mm (n = 166), and 5 mm (n = 78). The overall early survival rate was 97.32% after three months of placement. The highest early survival rate was at LAA (100%) and the lowest early survival rate was at UAA (95.9%). The implants 5 mm in diameter had the highest early survival rate (98.72%), while the implants 3.5 mm in diameter had the lowest early survival rate (94.57%). The ORs of the early implant survival were 4.7 [95% confidence interval (CI): 0.96-23.05)] and 4.42 (95% CI: 0.53-36.61) for the 4.3 mm and 5 mm implants, respectively, with no statistical significance. Conclusions The implants placed in the oral cavity had acceptable survival rates regardless of implant diameter or site of placement.

Influence of implant diameter on implant survival rate and clinical outcomes in the posterior area: a systematic review and meta-analysis.

OBJECTIVE: The aim of the present systematic review was to test the hypothesis that the diameter of implants inserted in the posterior area affects implant survival rate, prosthetic survival rate and peri-implant parameters (bleeding on probing (BoP), marginal bone loss (MBL), pocket probing depth (PPD)). MATERIALS AND METHODS: An electronic search of studies published until December 2021 was done on three databases (Pubmed, Scopus, Cochrane) independently by two authors. Clinical trials comparing implant survival rate, BoP, MBL and PPD among narrow diameter implants (NDI: ≥ 3.0 mm to < 3.75 mm) and regular diameter implants (RDI ≥ 3.75 mm to < 5 mm) were included. Data were independently extracted by two reviewers. Risk of bias was evaluated according to the Cochrane risk-of-bias tool for randomized studies and to the Joanna Briggs Institute Critical Appraisal tools for non-randomized ones. A pair-wise meta-analysis was conducted on the included studies. RESULTS: Seven articles were included out of the 4291 identified from the digital research. Overall, a total of 939 implants were inserted (319 NDI, 620 RDI). Only one study was judged at serious risk of bias. No statistically significant difference was found in implant survival rate (risk ratio 1.01 (95% CI [0.98 to 1.04], P = 0.67)) while the difference was significant for BoP (mean difference 2.89 (95% CI [0.30 to 5.48] mm, P = 0.03)) with higher values for NDI. Higher MBL was identified among regular diameter implants (mean difference -0.15 mm (95% CI [-0.32 to 0.01 mm], P = 0.07). No statistically significant differences were identified for prosthetic survival and PPD. CONCLUSIONS: No differences were found in implant survival rate between narrow and regular implants. A higher BoP was identified among narrow implants, but there was no higher bone loss. It is not possible to draw definitive conclusions about the use of narrow-diameter implants in the posterior region.

The Effect of Implant Length and Diameter on Stress Distribution of Tooth-Implant and Implant Supported Fixed Prostheses: An In Vitro Finite Element Analysis Study.

The aim of this study is to evaluate the effectiveness of the implant diameter and length on force dissemination of tooth-implant and implant retained fixed restorations. A finite analysis model was used via a 3D simulation of a unilateral mandibular Kennedy Class I arch. Through thresholding the resultant assembly, a region of interest was selected from the computed tomography (CT) scan. Details of the diameter (D) and length (L) of implant were introduced. Ds used were 3.7, 4.7, and 5.7, while Ls used were 10, 11.5, and 13. The constant was the use of rigid connectors in both designs (implant-implant and implant-tooth fixed partial dentures [FPDs]) and the mesial implant (D 3.7 and L 11.5). Stress in cancellous bone around mesial abutment, which is the second premolar in tooth-implant FPD and mesial implant in the implant-implant FPD, revealed that the stress was significantly lower in tooth-implant FPD when compared with implant-implant FPD (21.1 ± 0.00 vs 46.1 ± 0.00, P < .001). Stress distribution in the bone around any implant depends on several factors such as diameter, length, and tooth-implant vs implant-implant support. The implant diameter was more significant for improved stress distribution than implant length. A moderate increase in the length of the implant consequently reduced stress.

The Effect of Implant Length and Diameter on Stress Distribution around Single Implant Placement in 3D Posterior Mandibular FE Model Directly Constructed Form In Vivo CT.

A three-dimensional (3D) finite element (FE) model of the mandibular bone was created from 3D X-ray CT scan images of a live human subject. Simulating the clinical situation of implant therapy at the mandibular first molar, virtual extraction of the tooth was performed at the 3D FE mandibular model, and 12 different implant diameters and lengths were virtually inserted in order to carry out a mechanical analysis. (1) High stress concentration was found at the surfaces of the buccal and lingual peri-implant bone adjacent to the sides of the neck in all the implants. (2) The greatest stress value was approximately 6.0 MPa with implant diameter of 3.8 mm, approx. 4.5 MPa with implant diameter of 4.3 mm, and approx. 3.2 MPa with implant diameter of 6.0 mm. (3) The stress on the peri-implant bone was found to decrease with increasing length and mainly in diameter of the implant.

Correlation between Primary, Secondary Stability, Bone Density, Percentage of Vital Bone Formation and Implant Size.

BACKGROUND: This study aims to evaluate whether there is a correlation between implant stability, bone density, vital bone formation and implant diameter and length. METHODS: Ninety patients were enrolled in this study. They underwent a socket preservation procedure with allograft or PRF and after 4 months, a total of 90 implants were placed. CBCT scans were assigned prior to implant placement in order to assess the bone density. During the surgical re-entry, a bone biopsy was harvested with a trephine drill. Immediately after implant insertion, the primary stability was measured. The secondary stability was measured 4 months after implant placement. RESULTS: Primary stability showed a significant positive linear correlation with bone density (r = 0.471, p < 0.001) as well as with percentage of new bone formation (r = 0.567, p < 0.001). An average significant association of secondary stability with bone density (rs = 0.498, p < 0.001) and percentage of newly formed bone (r = 0.477, p < 0.001) was revealed. The mean values of primary stability in all three implant sizes, regarding the diameter of the implants, were similar (narrow 67.75; standard 66.78; wide 71.21) with no significant difference (p = 0.262). The same tendency was observed for secondary stability (narrow 73.83; standard 75.25; wide 74.93), with no significant difference (p = 0.277). CONCLUSIONS: The study revealed a high correlation between primary and secondary implant stability, and bone density, as well as with the percentage of vital bone formation. Implant length and diameter revealed no linear correlation with the implant stability.

Long-term clinical outcome of dental implants: A retrospective clinical study with a minimum follow-up between 9.5 and 17.7 years.

The aim of this retrospective case series was to evaluate the clinical and radiographic outcomes of the patients that underwent implant surgery in all indication classes, with a follow-up of at least 9 years. 121 healthy patients in need for oral rehabilitation with dental implants were included in this study. 196 implants (160 conical, 73 cylindric design implants) were inserted. The implant survival rate was the primary outcome. Intra- and postoperative complications were additional criteria for success. The mean follow-up of the patients was 12.29 years (SD 1.39). Mean age of the study population was 51.0 years (SD 12.7). The mean bone loss around implants after at least 9 years of loading was measured as 2.0 mm (SD 0.73 mm). Intra-operative complications were seen in 5 patients. Post-operative complications included: 5 mucositis,1 dehiscence, 2 screw loosening, 1 infection at site and 1 nonintegrated implant. Two implants were lost in two patients. The overall implant survival rate was 99.1%. As a conclusion, oral rehabilitation with dental implant-supported prostheses can be accepted as a safe procedure with relevantly high survival rates of oral implants and successful aesthetic and functional outcomes.

Effects of Different Implant Design Parameters on Mandibular Tooth Implantation / 医用生物力学

Objective To establish the implant-mandible model with different design parameters, observe stress distributions on the implant and surrounding bone, and analyze the influence of different design parameters on dental implant of the mandible. Methods Eight implant models were designed based on structural characteristic parameters (implant diameter, thread depth, height of abutment through gingiva, thread shape), and assembly of the mandibular model was performed respectively. The models were applied with static 150 N vertical and oblique 45° loads, so as to analyze peak von Mises stress of the implant and bone tissues and explore the structural parameter variables of implant most sensitive to peak von Mises stress. Results The peak stress of the mandible was larger under inclined load than that under vertical load. Implant diameter was the key factor affecting the peak von Mises stress of cortical bone, while thread depth was the key factor affecting the peak von Mises stress of cancellous bone. The peak von Mises stress was also affected by the height of abutment through gingiva, but the effect was not as significant as thread depth and implant diameter. Thread shape had little effect on the peak von Mises stress of the mandible. Conclusions Different implant design parameters can affect the peak stress of different tissues of the mandible, so it is necessary to carefully consider the selection of implant parameters for personalized implants. This study can provide theoretical guidance for structural parameter design of oral implants and provide references for accurate prediction of oral implants.

Impact of Intentional Overload on Joint Stability of Internal Implant-Abutment Connection System with Different Diameter.

PURPOSE: To evaluate the axial displacement of the implant-abutment assembly of different implant diameter after static and cyclic loading of overload condition. MATERIALS AND METHODS: An internal conical connection system with three diameters (Ø 4.0, 4.5, and 5.0) applying identical abutment dimension and the same abutment screw was evaluated. Axial displacement of abutment and reverse torque loss of abutment screw were evaluated under static and cyclic loading conditions. Static loading test groups were subjected to vertical static loading of 250, 400, 500, 600, 700, and 800 N consecutively. Cyclic loading test groups were subjected to 500 N cyclic loading to evaluate the effect of excessive masticatory loading. After abutment screw tightening for 30 Ncm, axial displacement was measured upon 1, 3, 10, and 1,000,000 cyclic loadings of 500 N. Repeated-measure ANOVA and 2-way ANOVA were used for statistical analysis (α = 0.05). RESULTS: The increasing magnitude of vertical load and thinner wall thickness of implant increased axial displacement of abutment and reverse torque loss of abutment screw (p < 0.05). Implants in the Ø 5.0 diameter group demonstrated significantly low axial displacement, and reverse torque loss after static loading than Ø 4.0 and Ø 4.5 diameter groups (p < 0.05). In the cyclic loading test, all diameter groups of implant showed significant axial displacement after 1 cycle of loading of 500 N (p < 0.05). There was no significant axial displacement after 3, 10, or 1,000,000 cycles of loading (p = 0.603). CONCLUSIONS: Implants with Ø 5.0 diameter demonstrated significantly low axial displacement and reverse torque loss after the cyclic and static loading of overload condition.

Short implants in posterior maxilla in elderly patients: A case series

@#<p>Placement of dental implants in reduced bone in the posterior maxilla requires maxillary sinus floor elevation. However, in elderly patients this is to be avoided. A case series on the successful placement of multiple short implants in posterior maxilla and splinted crown restorations in elderly patients was presented. Long term follow up revealed survival of the implants. Short implant is a suitable treatment option for elderly patients</p>

Influence of platform diameter in the reliability and failure mode of extra-short dental implants.

PURPOSE: To evaluate the influence of implant diameter in the reliability and failure mode of extra-short dental implants. MATERIALS AND METHODS: Sixty-three extra-short implants (5mm-length) were allocated into three groups according to platform diameter: Ø4.0-mm, Ø5.0-mm, and Ø6.0-mm (21 per group). Identical abutments were torqued to the implants and standardized crowns cemented. Three samples of each group were subjected to single-load to failure (SLF) to allow the design of the step-stress profiles, and the remaining 18 were subjected to step-stress accelerated life-testing (SSALT) in water. The use level probability Weibull curves, and the reliability (probability of survival) for a mission of 100,000 cycles at 100MPa, 200MPa, and 300MPa were calculated. Failed samples were characterized in scanning electron microscopy for fractographic inspection. RESULTS: No significant difference was observed for reliability regarding implant diameter for all loading missions. At 100MPa load, all groups showed reliability higher than 99%. A significant decreased reliability was observed for all groups when 200 and 300MPa missions were simulated, regardless of implant diameter. At 300MPa load, the reliability was 0%, 0%, and 5.24%, for Ø4.0mm, Ø5.0mm, and Ø6.0mm, respectively. The mean beta (ß) values were lower than 0.55 indicating that failures were most likely influenced by materials strength, rather than damage accumulation. The Ø6.0mm implant showed significantly higher characteristic stress (η = 1,100.91MPa) than Ø4.0mm (1,030.25MPa) and Ø5.0mm implant (η = 1,012.97MPa). Weibull modulus for Ø6.0-mm implant was m = 7.41, m = 14.65 for Ø4.0mm, and m = 11.64 for Ø5.0mm. The chief failure mode was abutment fracture in all groups. CONCLUSIONS: The implant diameter did not influence the reliability and failure mode of 5mm extra-short implants.

Considerations Regarding Dental Implant Surfaces, Bone Reaction and "Peri-implantitis".

This article explains, based on a long-term observation, the hard-tissue reaction to different endosseous implant surfaces and different implant designs. A patient who had received a full maxillary implant-supported restoration on basal implants and compression screws followed by immediate loading presented no clinical problems at the 20-year follow-up, but the X-ray examination revealed different hard tissue reactions to different implant types. No bone loss was found around lateral basal implants with fully polished vertical aspects, whereas crater-like bone loss was observed around the vertical shafts of implants with a roughened surface and macromechanical retentions. The case seems to indicate that roughened surfaces around the crestal transmucosal aspect of a dental implant may promote vertical bone loss and peri-implantitis.

Impacts of 3D bone-to- implant contact and implant diameter on primary stability of dental implant.

BACKGROUND/PURPOSE: This study investigated the effects of three three-dimensional (3D) bone-to-implant contact (BIC) parameters-potential BIC area (pBICA), BIC area (BICA), and 3D BIC percentage (3D BIC%; defined as BICA divided by pBICA)-in relation to the implant diameter on primary implant stability, as well as their correlations were also evaluated. METHODS: Dental implants with diameters of 3.75, 4, 5, and 6 mm and artificial bone specimens were scanned by microcomputed tomography to construct 3D models for calculating pBICA, BICA, and 3D BIC%. Indexes of the primary implant stability including the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) were measured after implants with various diameters were placed into bone specimens. The Kruskal-Wallis test, Wilcoxon rank-sum test with Bonferroni adjustment, and Spearman correlations were all performed as statistical and correlation analyses. RESULTS: The implant diameter significantly influenced pBICA and BICA, but not 3D BIC%. ITV and PTV were more sensitive to implant diameter than was ISQ. The coefficients of determination were high (>0.92) for the correlations between pBICA (or BICA) and indexes of the primary implant stability. CONCLUSION: This study revealed how the implant diameter and the three-dimensional (3D) BIC influence the primary stabilities of dental implant. ITV and PTV were more sensitively influenced by the implant diameter than ISQ. The pBICA and BICA seem to be more important than 3D BIC % for using wider implant in treatment plan, since those two parameters are highly predictive of variations in the primary stability of dental implant.

Impact of implant diameter and length on stress distribution in osseointegrated implants: A 3D FEA study.

AIMS AND OBJECTIVES: Dimension of dental implant is an important parameter which has a considerable impact on the biomechanical load transfer characters and its prognosis. Excessive stress in the bone-implant interface may result in the failure of the implant. The aim of this study was to evaluate the impact of implant diameter and length on neighboring tissues around the implant. The results of the study will help in developing a scientific methodology to select appropriate implant diameter and length. MATERIALS AND METHODS: In this study, tapered implants of different diameter and length were numerically analyzed using bone-implant models developed from computed tomography generated images of mandible with osseointegrated implants. The impact of various diameters on stress distribution was examined using implants with a length of 13 mm and diameters of 3.5 mm, 4.3 mm and 5.0 mm. Implants with a diameter of 4.3 mm and lengths of 10 mm, 13 mm, 16 mm was developed to examine the impact of various implant length. All materials were assumed to be linearly elastic and isotropic. Masticatory load was applied in a natural direction, oblique to the occlusal plane. The Statistical Package for the Social Sciences software package was used for statistical analysis. RESULTS: Maximum von Mises stresses were located around the implant neck. It was demonstrated that there was statistically significant decrease in von Mises stress as the implant diameter increased. CONCLUSION: Within the limitations of this study there was statistically significant decrease in von Mises stress as the implant diameter increased.