Conical Connection Research Articles

The effect of implantoplasty on dental implant fracture resistance: a systematic review

An increase in dental implant placements in recent years has seen a growth in the reported cases of post-operative complications such as peri-implantitis. One of the available treatment modalities to overcome such complications is implantoplasty. Although this procedure is not new, the long-term effect of implantoplasty has not been addressed extensively. The aim of this systematic review was to investigate the change in fracture resistance of dental implants after implantoplasty. Three electronic databases and reference lists of included studies were searched to assess the potential effect of implantoplasty on implant fracture resistance. Titles and abstracts were screened by two reviewers in parallel. The extracted information regarding implant fracture resistance was reported based on the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. A total of 56 studies were identified, of which, nine studies were included. Narrow platform implants (<3.75 mm) were more susceptible to fracture following implantoplasty compared to wider platforms (?5 mm). Implants with internal hexagon connection may have a higher risk of fracture after implantoplasty compared to other connection designs such as external hexagon and conical connections. Other potential factors which may affect implant fracture resistance after implantoplasty include crown to implant ratio, implant material, and the amount of peri-implant bone loss. Within the limitation of in vitro studies, there is no clear evidence to demonstrate the effect of implantoplasty on implant fracture resistance. Methodological differences between the available studies did not allow for clear comparison between them. Furthermore, the limited amount of clinical reports of this resective procedure, in combination with patient and operator variability, affect the clinical assessment of this treatment modality.

A retrospective study of 12,538 internal conical connection implants focused on the long-term integrity of implant-abutment complexes.

To evaluate the long-term integrity of implant-abutment complexes in implant systems with two internal conical angles. 12,538 bone-level implants of two systems placed between January 2012 and December 2018 were retrospectively analyzed. Cumulative abutment/implant fracture rates in systems with larger (LA, 7.5°) and smaller (SA, 5.7°) internal conical angles were estimated using the Kaplan-Meier analysis and compared between groups. The association between implant systems and jammed abutment retrievability was evaluated by multivariable generalized estimating equation logistic regression modeling. For LA, the 8-year cumulative incident rate was 0.10% (95% confidence interval (CI): 0-0.24%) for implant fracture and 0.26% (95% CI: 0.11%-0.41%) for abutment fracture, demonstrating a significant difference in gender (p=.03), implant diameter (p=.01), jaw (p=.006), and antagonist tooth (p<.001). For SA, the 8-year cumulative incident rate was 0.38% (95% CI: 0-0.79%) for implant fracture and 2.62% (95% CI: 0.05%-5.13%) for abutment fracture, which was influenced by implant diameter (p<.001) and site (p=.03). The cumulative implant/abutment fracture rate was lower for LA implants, particularly for LA implant-supported single crowns (SCs) (p<.05). The abutment-retrieval success rate was 92.9% for LA and 57.1% for SA (p=.055). LA implants exhibited a lower incidence of fracture in abutment-implant complexes and a relatively higher retrievability success rate for jammed abutments.

Influence of Implant Scanbody Wear on the Accuracy of Digital Impression for Complete-Arch: A Randomized In Vitro Trial.

The aim of this study was to evaluate the influence of implant scanbody (ISB) wear on the accuracy of digital impression for complete-arch. A polymethylmethacrylate (PMMA) edentulous mandibular model with four internal hexagonal interlocking conical connections was scanned with an extraoral optical scanner to achieve a reference file. Four cylindrical polyetheretherketone (PEEK) ISBs were scanned 30 times with IOS, and the test files were aligned to the reference file with a best-fit algorithm. For each analog linear (ΔX, ΔY and ΔZ-axis) and angular deviations (ΔANGLE) were assessed. Euclidean distance (ΔEUC) was calculated from the linear deviation, reporting a mean of 82 µm (SD 61) ranging from 8 to 347 µm. ΔANGLE error mean was 0.33° (SD 0.20), ranging from 0.02 to 0.92°. From a multivariate analysis, when ΔEUC was considered as a response variable, a significant influence of ISB wear by scan number in interaction to position for implant 3.6 was identified (p < 0.0001); when ΔANGLE was considered as a response variable, a significant effect of position 3.6 was recorded ((p < 0.0001). The obtained results showed that the ISB wear negatively influenced the accuracy of IOS, suggesting that ISB base wear could be detrimental for the seating of ISBs on angulated implants.

Monolithic zirconia single tooth implant-supported restorations with CAD/CAM titanium abutments in the posterior region: A 1-year prospective case series study.

PurposeTo assess the clinical, radiographic, and patient‐reported outcome measures, including the success of screw‐retained monolithic zirconia implant‐supported restorations with CAD/CAM titanium abutments in the posterior region during a 1‐year follow‐up.MethodsIn a prospective case series, 50 molar sites in the posterior region of 46 patients with a minimum age of 18 years and sufficient bone volume and anatomical conditions for placing an implant (≥8 mm) and an anatomical restoration were included. Parallel‐walled implants with a conical connection were inserted in a two‐stage surgical procedure. Implant uncovering and healing abutment placement occurred 12 weeks after insertion. Two weeks after mucosa healing, a screw‐retained monolithic zirconia restoration with a CAD/CAM titanium abutment was placed. Clinical, radiographic, and patient‐reported outcome measures were collected at baseline before implant placement and then during the 1 month and 1 year follow‐ups.ResultsAt the 1 year follow‐up, 49 restorations could be evaluated. The plaque accumulation, presence of calculus, bleeding tendency and peri‐implant inflammation indices were low, representing healthy peri‐implant conditions. The mean marginal bone level change between the 1 month and the 1 year follow‐up was −0.17 ± 0.46 mm. The mean patient satisfaction was high. The restoration success was, according to the modified USPHS criteria, 95.9%.ConclusionMonolithic zirconia implant‐supported restorations with CAD/CAM titanium abutments have very good clinical, radiographic and patient‐reported outcomes after 1 year in function.

Management of Fixed Rehabilitation of Single Implants in the Aesthetic Sector: A Systematic Review

Introduction When dental implants are installed and subjected to functional loads, marginal bone resorption is frequent, also in sites not affected by peri-implantitis, and it can be a critical factor that will affect the aesthetics and longevity of the implant because it is associated with an increased risk of peri-implantitis and soft tissue collapse. Objective To assess the peri-implant marginal bone loss and the survival percentage of implant restorations that present internal and external prosthetic connections. Material and methods A systematic review of the literature was carried out. Various information sources were consulted such as PubMed, Embase, Ovid, Scopus databases. For the search process, the methodology approved by the PRISMA Guide was followed. Results 5 articles were found that met the established criteria. In these articles, 2,866 patients rehabilitated by means of 6,455 implants were registered, of which 3,057 were restored with an external hexagonal prosthetic connection and 3,398 with an internal connection of the hexagonal or conometric type. The 3,057 implants prosthetized by connection to an external hexagon showed a mean peri-implant marginal bone loss of 0.986 ± 0.58mm. The 3,398 implants prosthetized by means of an internal hexagon or conometric type connection highlighted a mean peri-implant marginal bone loss of 0.86 + - 0.43mm. Conclusion Taking into consideration the individual characteristics of each patient and each situation, the literature seems to indicate that on the intensity of the mechanical stress and the tensions emitted to the peri-implant region, the conical connection and the cylindrical design of the implant transmit less stress to the cortical bone. Bone with respect to the external hexagonal connection and the conical design of the implant, which transmit less stress and tension to the trabecular bone and more to the cortical bone.

Comparison between Early Loaded Single Implants with Internal Conical Connection or Implants with Transmucosal Neck Design: A Non-Randomized Controlled Trial with 1-Year Clinical, Aesthetics, and Radiographic Evaluation.

To evaluate the implant and prosthetic of two implants with different surfaces and neck design. Enrolled patients received bone level, 12° conical connection implants (Nobel Parallel, Nobel Biocare; NOBEL group) with anodized surface (TiUnite) and roughness of 1.35 μm, or transmucosal implant system (Prama, Sweden and Martina; PRAMA group) with convergent collar, ZIrTi surface, and roughness 1.4–1.7 μm. Both implants were made of pure grade IV titanium, with similar diameter and length, chosen according to the dentistry department availability and patient’s request. After early prosthesis delivery, patients were filled for at least one year. Outcome measures were: implant and prosthetic survival and success rates, physiological marginal bone remodeling, periodontal parameters and pink esthetic score (PES). Results: Fifteen patients were allocated and treated in each group. At the one-year follow-up, three patients dropped out, one in the NOBEL group and two in the PRAMA group. During the entire time of investigation, all implants survived and the prostheses were successful. No statistically significant differences were found in term of marginal bone loss, periodontal parameters, and aesthetics (p > 0.05). Conclusion: With the limitations of the present study, both implant systems showed successful clinical results. Finally, many other clinical and surgical variables may influenced marginal bone levels, implant survival, and periodontal parameters. More homogenous clinical trials with larger samples are needed to confirm these preliminary conclusions.

Immediately provisionalized tapered conical connection implants for single-tooth restorations in the maxillary esthetic zone: a 5-year prospective single-cohort multicenter analysis

ObjectivesThis open, single-cohort, multicenter, prospective study investigated the efficacy of immediately provisionalized tapered conical connection implant for single-tooth restorations in the anterior and premolar regions of the maxilla after 5 years of function.Materials and methodsAll implants were placed in healed sites and immediately provisionalized. MBLs, soft-tissue parameters, and oral-health impact profile (OHIP) were evaluated at implant insertion, 6, 12, 24, 36, and 60 months. Paired Wilcoxon signed-rank tests and Kaplan–Meier survival analysis was used for statistical and implant survival/success analyses, respectively.ResultsSeventy-seven patients (81 implants) completed the 5-year follow-up. The 5-year cumulative survival and success rates were 97.8%, and the mean MBL change from implant insertion to 5 years was − 0.80 ± 1.13 mm. Optimal papilla index scores were observed at 90.1% of sites at 5 years compared with 32.8% of sites at insertion. Pink esthetic score, modified bleeding and plaque indices, and OHIP showed statistically significant improvement at the 5-year follow-up.ConclusionsImmediately provisionalized tapered conical connection implants promote marginal bone stability and excellent esthetic outcomes after 5 years of function.Clinical relevanceThis treatment is a viable option for patients requiring immediately provisionalized single-tooth restorations in the esthetic zone and shows favorable long-term clinical outcomes, including marginal bone stability and excellent esthetics.

Five-Year Prospective Study on Implant Failure and Marginal Bone Remodeling Expected Using Bone Level Implants with Sandblasted/Acid-Etched Surface and Conical Connection.

The purpose of the present prospective, case-series study was to report implant survival rate and marginal bone remodeling expected 5 years after loading using dental implants placed in daily practice. This research was designed as an open-cohort, prospective, case-series evaluation. Any partially or completely edentulous patient, scheduled to receive at least one bone level implant, was considered eligible for this study. Primary outcome measurements were: implant and prosthetic cumulative survival rate and any complications experienced up to the 5-year follow-up. Secondary outcome measures were: thickness of gingival biotype, implant insertion torque, implant stability quotient, and marginal bone loss (MBL). Ninety consecutive patients (34 males and 56 females, aged between 24 and 81 years old [mean: 53.2 ± 15.4]) with 243 inserted implants were followed for at least 5 years after loading (mean: 65.4 ± 3.1 months; range from 60 to 72). At the 1-year follow-up, no drop-outs were recorded, but 17 patients (18.9%) with 18 restorations (12.6%) delivered on 34 implants (14%) were lost at the 5-year examination. At the 5-year follow-up examination, six implants lost osseointegration (97.5%). In the same period, four prostheses failed (97.2%). Five complications were reported in five different patients (prosthetic success rate was 96.5%, at patient level). Five years after loading, the mean MBL was 0.41 ± 0.30 mm. The difference from the 1-year data was 0.04 ± 0.19 mm. A statistically significant higher MBL was found for smokers, and patients with thin gingival biotype. The mean implant insertion torque was 42.9 ± 4.8 Ncm (range from 15 to 45 Ncm). Two-hundred and three implants (83.5%) were inserted with an insertion torque ≥35 and ≤45 Ncm. High implant survival and success rate could be expected with stable marginal bone remodeling up to 5 years after loading. Smoking and thin tissue biotype were the most important variabilities associated with higher MBL. Further research studies are needed to confirm these results.

Fracture Resistance of Zirconia Abutments with or without a Titanium Base: An In Vitro Study for Tapered Conical Connection Implants.

Dental implants with tapered conical connections are often combined with zirconia abutments for esthetics; however, the effect of the titanium base on the implant components remains unclear. This study evaluated the effects of a titanium base on the fracture resistance of zirconia abutments and damage to the tapered conical connection implants. Zirconia (Z) and titanium base zirconia (ZT) abutments were fastened to Nobel Biocare (NB) implants and Straumann (ST) implants and subjected to static load testing according to ISO 14801:2016. The experiments were performed with 3 mm of the platform exposed (P3) and no platform exposed (P0). The fracture loads were statistically greater in the titanium base abutments than the zirconia abutments for the NB and ST specimens in the P0 condition. In the P3 condition of the ST specimens, the deformation volume of the ZT group was significantly greater than the Z group. The titanium base increased the fracture resistance of the zirconia abutments. Additionally, the titanium base caused more deformation in the P3 condition. The implant joint design may also affect the amount of damage to the implants when under a load. The mechanical properties of the abutment should be considered when selecting a clinical design.

Assessment of Clinical and Radiological Outcome of Implant with Two Different Connections Con iguration: A Controlled Trial.

Objective:The objective of the study is to compare two different implant designs having different neck configuration and neck interfaces.Materials and Methods:Fifty subjects were randomly divided into 2 groups, each containing 25 subjects. In Group I, conical connection (CC) (Nobel Biocare) with back-tapered collar dental implant and in Group II, external-hexagon (EH) (Nobel Biocare) with flat-to-flat implant-abutment interface dental implant was used. Radiographic marginal bone crest level and marginal bone loss (MBL) were compared.Results:A significant less MBL was seen in Group I compared to Group II recorded at different intervals of time (P < 0.05).Conclusion:CC implants with back-tapered collar exhibited less MBL as compared to EH implants with flat-to-flat implant-abutment interface.

Comportamento biomecânico de implantes com conexão protética tipo morse (cônica), com diferentes angulações na interface implante-pilar em próteses múltiplas: estudo de elementos finitos

ABSTRACT Objective: Evaluate the biomechanical behavior of the influence of different internal angles of conical prosthetic connections in fixed partial prostheses of three elements, through the tridimensional finite element method. Methods: Two different models of segment of the posterior portion of the mandible, with two implants with conical connections at angulations of 11.5 and 16 degrees. Afterwards, and occlusal load of 180N was used, and divided into 2 points of application on the premolar, and 400N divided into 5 points of application on the molar. Data were acquired as the tensile, compressive and shear stresses on cortical and medullary bone, and von Mises stresses on implants and prosthetic components of two implants in both in three-unit fixed partial prosthesis. In the quantitative analysis, both in cortical and medullary bone, the tension peaks in tensile, compression, and shear forces were higher for the CM16 group. Results: When analyzing qualitatively, the cortical and medullary bones presented a greater stress around the implant platform with a higher incidence in the implant in the molar region. In the von Misses analysis in both groups, the tensions were concentrated in the cervical region of the implants, in the first threads, in the premolar and molar regions. Regarding prosthetic pillars, the stress concentration was located in the region of contact with the implant. Conclusion: The increased angulation of conicity of the internal conical connections represents a determinant factor to increase in stress concentration in the implants, prosthetic components and adjacent structures, such as the cortical and medullary bone.

Finding Better Ways to Perform Graftless Full Rehabilitation of a Compromised Maxilla: New Platform-Switched Zygomatic Implants Placed Extra-Sinus Improve Prosthetic Restoration—A Preliminary Study of 25 Cases and 85 Implants

Standard treatment for full rehabilitation of compromised maxillae with regular implants includes sinus elevation grafting, a minimum of two to three surgeries, and a minimum treatment time of 9 to 15 months. Zygomatic implants are a viable alternative. However, prosthetic restorations have been compromised due to abutments emerging on the palate. The purpose of this study was to find ways that abutments will emerge on the ridge (occlusal surface). The presented results show it can be done if zygomatic implants are placed in the sinus wall (extra-sinus) and use an internal, conical connection with platform-switching and 45-degree abutments. Thus, marginal tissue prognosis and primary stability may also be improved by adding coronal threads to an implant design. These improvements, if confirmed in longer follow-ups and further studies, may encourage more graftless rehabilitations of severely compromised maxillae, reducing the number of surgeries and overall treatment time.

Efeito do posicionamento crestal do implante na estabilidade primária antes e após carga: um estudo in vitro

Abstract Introduction Primary stability is one of the goals of modern implant dentistry and if achieved, reduces treatment time for prosthetic rehabilitation and the number of interventions made in patients mouth. Several companies state as protocol for connical conection implants, a subcrestally positioning. Objective This in vitro study aimed to evaluate the effect of placing a conical connection implant equicrestally and subcrestally on static and loading condition in two types of bone density. Material and method A total of 200 bone cylinders were extracted from femur of pigs, standardized by means of x-rays and computerized microtomography scan (microCT) and separated in low and high density specimens. The implants were placed on the center of the bone cylinders and were evaluated before and after loading by means of microCT and histomorphometry. Result The results showed that placing the evaluated implant subcrestally provided better primary stability and performance on static and loading situations on low and high density bone. Conclusion Placing implant subcrestally improve primary stability outcomes under loading and static situations.

Oscillatory Potentials in Achromatopsia as a Tool for Understanding Cone Retinal Functions.

Achromatopsia (ACHM) is an inherited autosomal recessive disease lacking cone photoreceptors functions. In this study, we characterize the time-frequency representation of the full-field electroretinogram (ffERG) component oscillatory potentials (OPs), to investigate the connections between photoreceptors and the inner retinal network using ACHM as a model. Time-frequency characterization of OPs was extracted from 52 controls and 41 achromat individuals. The stimulation via ffERG was delivered under dark-adaptation (DA, 3.0 and 10.0 cd·s·m−2) to assess mixed rod-cone responses. The ffERG signal was subsequently analyzed using a continuous complex Morlet transform. Time-frequency maps of both DA conditions show the characterization of OPs, disclosing in both groups two distinct time-frequency windows (~70–100 Hz and >100 Hz) within 50 ms. Our main result indicates a significant cluster (p < 0.05) in both conditions of reduced relative power (dB) in ACHM people compared to controls, mainly at the time-frequency window >100 Hz. These results suggest that the strongly reduced but not absent activity of OPs above 100 Hz is mostly driven by cones and only in small part by rods. Thus, the lack of cone modulation of OPs gives important insights into interactions between photoreceptors and the inner retinal network and can be used as a biomarker for monitoring cone connection to the inner retina.

Marginal Bone Loss around Implants with Internal Hexagonal and Internal Conical Connections: A 12-Month Randomized Pilot Study.

The aim of this study was to analyze the differences in terms of the marginal bone level (MBL) around implants with either an internal conical or an internal hexagonal implant–prosthesis connection. A randomized clinical trial included patients in need of a single implant-supported restoration. The implant–prosthesis connection was either internal conical or internal hexagonal while maintaining the same type of implant macro- and microarchitecture. Clinical and radiographical variables were registered up to 12 months of follow-up, including MBL. A total of 30 patients were included in the study. The main outcome variable, MBL 12 months after prosthesis delivery, was statistically different in both groups: −0.25 (0.12) vs. −0.70 (0.43) (conical vs. hexagonal; p = 0.033). Differences were also observed at the 3- and 6-month follow-up visits as well as for the MBL change from prosthesis delivery to the 12-month follow-up (−0.15 (0.13) vs. −0.56 (0.44); conical vs. hexagonal; p = 0.023). Correlations between MBL around the implants and radiographic measurements on the adjacent teeth, buccal bone to implant, tissue thickness or keratinized tissue were not significant neither globally nor when analyzed independently by group. In view of such results, it can be concluded that single-unit restorations with internal hexagonal-connection implants induce higher marginal bone loss after 12 months of follow-up from prosthesis delivery than internal conical-connection implants.

The use of implant-level connection in screw-retained fixed partial dentures: A 3-year randomised clinical trial.

This randomised controlled trial compares the 3-year outcomes, that is, marginal bone-level (MBL) changes and clinical parameters, between an abutment-level (AL) and implant-level (IL) connection for implants with an internal conical connection (ICC) supporting a screw-retained fixed partial denture. Fifty patients with 119 implants were randomly allocated to either the AL or IL group. Radiographic and clinical examinations were performed after one, two, and 3years. A linear mixed model was used to evaluate the differences between groups. The MBL change was not significantly different between the groups at any point. The MBL was 0.12±0.31mm (AL) and 0.23±0.26mm (IL) after 1year; 0.15±0.34mm (AL) and 0.17±0.22mm (IL) after 2years; 0.18±0.39mm (AL) and 0.15±0.21mm (IL) after 3years. The bleeding on probing was 43.44±39.24% (AL) and 58.19±41.20% (IL) after 1year; 35.78±39.22% (AL) and 50.43±41.49% (IL) after 2years; 51.27±44.63% (AL) and 49.57±37.31% (IL) after 3years and was significantly different (p=.025) between 1 and 2years. The probing depth showed a significant difference at each time point while the plaque was not significant between the groups. The overall technical, biological and prosthetic complication rates were 5.04%, 3.36%, and 16.00%, respectively. The MBL change was similar in the groups. The slight differences in the soft tissue complications between the groups are likely not of clinical relevance. An IL connection is considered to be a valid alternative to an AL set-up in ICC implants.

To Review the Effect of Tightened and Loosened Torque on Two Different Implant–Abutment Connection Designs

Introduction: It is crucial to take care of stability between various implant parts for the general success rate of the reconstruction. Component fit, saliva contamination, machining accuracy, and screw preload influence the steadiness of implant–abutment connection. Loosening of abutment screws has been a well-known technical problem. Aim: The aim of this study was to gauge repeated tightening and loosening torque on two commercially available implant/abutment connection designs. Study Design: This was an in vitro study. Methodology: A total of 32 implant analogs samples using a metal die with, metal ring of 20mm x 20mm x 20mm in size and a hole in the center were prepared. For both the groups, the implant analog was axially threaded within bases. They were clasped at an edge parallel to the standard minimal bone position. A 35 N/cm torque was enforced, each implant and abutment connection in both the groups using toque ratchet. After 20 min, screws were loosened and detorque measurement was recorded up to ten times. Scanning electron microscope micrographs of selected screws also are presented. SPSS (21.0 version) was used for analyzing data. Results: The mean residual torque for Group 1 was − 51.45 and Group 2 was − 43.29. The RTq (%) was found to be significantly less (0.028*) among Group 2: conical connection as compared to Group 1: butt joint connection. Conclusion: The loosening torque was significantly less in conical connection as compared to butt joint connection.

Prosthetic complications of fixed dental prostheses supported by locking-taper implants: a retrospective study with a mean follow-up of 5\xa0years

BackgroundRestoration with locking-taper implants is a widely used methodology. However, conical connection systems such as locking-taper implant systems have rarely been examined. This study provides a retrospective investigation of locking-taper fixed restorations, mainly focusing on prosthetic complications.MethodsPatients undergo treatment with conical connected implants from 2008 to 2010 were examined. Preparation of the implant sites was performed according to the standard procedures for the Bicon system. Bone healing took over 6 months, and the prosthetic procedure was initiated thereafter. Integrated abutment crowns or gold porcelain crowns were used, and the prosthesis type was a single crown or a fixed dental prosthesis. Once the crown was in place, its occlusion was thoroughly checked and adjusted, and then the crown was glazed or finely polished. The Kaplan–Meier method was used to calculate the cumulative complication-free rates for 5 and 10 years. Additionally, a Cox regression model was used to identify the factors that independently influenced the results. Implant survival and marginal bone loss were also investigated.ResultsA total of 392 patients who underwent 541 implants and 434 locking taper implant-based restorations from 2008 to 2010 were examined. The overall 5-year cumulative complication-free rate was 83.34%. The most common prosthetic complication was veneer chipping, with a frequency of 67.53%. According to the Cox regression model, the complication-free rate of integrated abutment crowns was significantly higher than that of gold porcelain crowns, that of molar regions was significantly higher than that of premolar regions, and that of females was significantly higher than that of males. Only three implant failures happened, and the mean marginal bone loss values at 1- year, 5-years and 10- years were 0.25 mm (95% CI ± 0.12), 0.40 mm (95% CI ± 0.03) and 0.51 mm (95% CI ± 0.05), respectively.ConclusionVeneer chipping was the most common complication with locking-taper implant-supported fixed restorations. The incidence of complications for IACs is significantly higher than that for GPCs. Age, location, and prosthesis type are not determinants of prosthetic complications. Besides, the long-term clinical effect of locking-taper implant can meet the clinical needs. The bone tissue level around the implant can maintain long-term stability.

Reliability and Correlation of Different Devices for the Evaluation of Primary Implant Stability: An In Vitro Study

Our aim was to analyze the correlation between the IT evaluated by a surgical motor and the primary implant stability (ISQ) measured by two RFA devices, Osstell and Penguin, in an in vitro model. This study examines the effect of bone type (soft or dense), implant length (13 mm or 8 mm), and implant design (CC: conical connection; IH: internal hexagon), on this correlation. Ninety-six implants were inserted using a surgical motor (IT) into two types of synthetic foam blocks. Initial measurements for both the peak IT and ISQ were recorded at the point when implant insertion was stopped by the surgical motor, and the final measurements were recorded when the implant was completely inserted into the synthetic blocks using only the RFA devices. Our null hypothesis was that there is a good correlation between the devices, independent of the implant length, design, or bone type. We found a positive, significant correlation between the IT, and the Osstell and Penguin devices. Implant length and bone type did not affect this correlation. The correlation between the devices in the CC design was maintained; however, in the IH design it was maintained only between the RFA devices. We concluded that there is a high positive correlation between the IT and ISQ from a mechanical perspective, which was not affected by bone type or implant length but was affected by the implant design.

Probability of survival and stress distribution of narrow diameter implants with different implant-abutment taper angles.

This study evaluated the probability of survival, failure mode, and stress distribution of narrow diameter implants (NDIs) with internal implant-abutment conical connection comprised of different taper angles and thread designs. Sixty-three NDIs (Ø 3.5× 8.5 mm) were divided according to the taper angle (TA), internal diameter (ID), and trapezoidal thread design (TD) (n=21/group), as follows: (a) 11.5°U (11.5° TA; ID: 2.5 mm; TD: dual threaded); (b) 11.5°S (11.5° TA; ID: 2.5 mm; TD: single threaded); (c) 16°S (16° TA; ID: 2.72 mm; TD: single threaded). They were subjected to step-stress accelerated life testing. The reliability and use-level probability Weibull curves were calculated at 50, 100, and 150 N for a mission of 100,000 cycles and the failure mode was analyzed using a scanning electron microscope. For finite element analysis the von-Mises stress (σvM ) was calculated for the abutment and implant. All groups showed high reliability (above 84%) and failures occurred predominantly in the abutment. In the FEA, 11.5°U showed higher σvM for the implant. All NDIs showed high reliability at clinically challenging loads. The system with greater taper angle showed lower σVm in the implant, and dual threaded implants showed a higher stress concentration in the implant and cortical bone.