Conical Abutment Research Articles

Preclinical Validation of a Novel Device Designed to Reduce Biofilms on Percutaneous Osseointegrated Abutments.

To assess the efficacy of a prototype cleaning device in removing biofilm from skin-penetrating abutments. Adverse skin reactions around percutaneous osseointegrated implants have been linked to poor hygiene and infection. A cleaning device made from open-cell polyfoam has been developed to facilitate manual cleaning of abutments by the patient. Serratia biofilm was grown on clean and sterile conical bone-anchored hearing system abutments including both pre-2007 (straight sided) and post-2007 (conical-sided) designs. Eighteen were photographed and then subjected to cleaning using a toothbrush or the cleaning device soaked in water or a proprietary mouthwash. Biofilm on a further group of 10 conical abutments was recorded using a scanning electron microscope before and after cleaning with the test device soaked in water. Quantitative analysis of the efficiency of the cleaning was made using image analysis. Removal of biofilm using a dry or wet toothbrush was not as effective as cleaning with the device. In 10 cases subjected to image analysis, approximately 90% of the biofilm was removed from the top third of the abutments, 85% from the middle third, and 48% from the basal third. The cleaning device is effective in removing most biofilm from the test abutments and represents a significant improvement in comparison with traditional methods such as a toothbrush.

Marginal and internal fit of CAD/CAM frameworks in multiple implant-supported restorations: Scanning and milling error analysis.

Despite computer-aided design and computer-aided manufacturing (CAD/CAM) technology improving prosthesis fit, errors inherent to digital workflow still exist. To measure scanning/milling errors, and identify factors influencing marginal (MD) and internal discrepancy (ID). After scanning, 22 conical abutments in 5 master casts, 6 suprastructures with more than 2 implants (3, 4, and 6) were CAD designed. Angular deviation and errors in the vertical/horizontal planes were analyzed using a coordinate measuring machine (CMM). CAD suprastructures were milled and MD/ID evaluated with micro-computed tomography (CT) and optic microscopy (OM) at one screw test (OST) and final fit test (FFT). Mean scanning errors, at the vertical/horizontal planes, and angulation error were 3 μm ± 13, 44 μm ± 34, 0.3° ± 0.2°, respectively. Angulation errors nearly double in structures >3 abutments (0.26°vs 0.4°). OM MD in FFT/OST was 57.7 μm ± 13.9/100.7 μm ± 34.6, respectively. Micro-CT FFT-MD was 38.9 μm ± 12.8. Lineal/perimetral ID was 49.6 μm ± 11.9 and 108.2° ± 41.8, respectively. Structures >3-implants were 2.3 times more likely to present higher MD (CI95%:0.4-13.6). Nearly all the internal horizontal gap was due to scanning errors (44 of 49.6 μm). Horizontal scanning errors were three times more likely to present greater ID (CI95%:0.5-17.4). Horizontal plane scanning errors are greater than vertical errors. Scanning angulation/milling errors are higher for suprastructures>3implants. Scanning/milling errors are associated with ID/MD, respectively, leading to micro-gap formation. A CMM reduces scanning errors in >3-implant-frameworks before milling the final piece.

Failure Probability, Stress Distribution and Fracture Analysis of Experimental Screw for Micro Conical Abutment.

The aim of this study was to evaluate the failure probability of two types of abutment screws after compressive load and to analyze the stress distribution with finite element method. Sixty (60) single-tooth implant restorations were assembled on titanium implants (e-fix, A.S. Technology - Titanium Fix). The groups were divided into Conventional screw (Screw neck 1.5 ø mm) and Experimental screw (Screw neck constricted with 1.2 ø mm). Specimens were subjected to single load to failure with compressive test according ISO 14801. The fractured specimens were subjected to stereomicroscopy for measurement of remaining screws inside the implant and characterization of fracture origin. Representative specimens were analyzed by scanning electronic microscopy. For finite element method (FEM), an identical 3D model of the two in vitro test groups were used with similar conditions (30º, 100 N load). The stress in the abutment screw was analyzed by von-Mises criteria. The results of strength means were 4132.5 ± 76 MPa and 4528.2 ± 127.2 for conventional and experimental groups, respectively. During microscopy, the mean (mm) of the remaining screw piece inside the implants were 0.97 ± 0.23 and 1.32 ± 0.12 for conventional and experimental groups, respectively. In FEM, the conventional group showed stress concentered in an unfavorable region (peak of 39.23 MPa), while the experimental group showed more stress areas but less concentration than the conventional group (36.6 MPa). In using the tested experimental geometry, the abutment screw can have its strength improved, and the origin of failure can be more favorable to clinical resolution.

The Role of Implant-Tooth Distance on Marginal Bone Levels and Esthetics.

The peri-implant bone and mucosa architecture contribute to the health and esthetics of single-tooth dental implants. The implant-tooth distance (ITD) has been regarded as a key determinant of their outcomes. This study was conducted to determine the relationship between ITD and peri-implant bone, mucosa, and pink esthetic scores (PES) for anterior single-tooth implants. For 44 dental implants with a microthread conical abutment interface design placed in 38 participants, periapical radiographs and photographs were evaluated at 1 and 4 years to assess interproximal bone levels and PES. Mean mesial and distal marginal bone level change over 4 years was 0.20 ± 1.00 mm and 0.20 ± 0.74 mm, respectively. In this cohort there was no relationship between ITD and interproximal bone changes or papilla fill at 4 years; however, marginal bone changes influenced PES score-the smaller the ITD, the lower the PES (P < .001). Alone, ITD did not influence marginal bone levels or papilla in this cohort. These results imply a complex relationship between ITD, marginal bone levels, and PES scores for single-tooth implants.

Evaluation of Implant Stability of Supported Mandibular Overdenture Retained by Telescopic Crowns Over Screw Retained and Self-locking Conical Abutment Connection

Evaluation of Implant Stability of Supported Mandibular Overdenture Retained by Telescopic Crowns Over Screw Retained and Self-locking Conical Abutment Connection

Mechanical Behavior of Different Micro Conical Abutments in Fixed Prosthesis.

To evaluate the biomechanical behavior between two different micro conical abutments: two-piece and one-piece abutments. Four groups were divided according to the prosthetic connection (internal or external hexagon) and abutment type. The vertical misfit between the abutment and implant was evaluated under stereomicroscope. Next, the implants were divided into pairs and embedded in polyurethane to receive two-element prostheses. The initial removal torque was measured for abutments and for prosthesis fixation. The samples were mechanically cycled (200 N, 2 Hz, 2 × 106 cycles) before measuring the torque loss in the same regions. For stress verification, a finite element analysis was used. For vertical misfit, one-piece (4.70 ± 0.26 μm) < two-piece (16.8 ± 0.32 μm). For preload in abutment screw, two-piece = one-piece. For prosthetic screw, a higher percentage of preload was found for two-piece, but no statistical difference was observed after fatigue cycling between the groups. For stress analysis, no difference (10%) was observed for abutments, retention screw, or for the bone. The one-piece abutment maintained even amounts of preload after cyclic loading and presented less vertical misfit in comparison with the two-piece abutment for both implant connections. The use of one-piece abutments did not increase the stress and strain concentration, suggesting acceptable biomechanical behavior.

Marginal soft tissue stability around conical abutments inserted with the one abutment-one time protocol after 5 years of prosthetic loading.

Soft tissue stability is crucial to obtain and maintain optimal esthetic results. This study aimed to investigate, over 5 years, the soft tissue response using a conical abutment together with the "one-abutment one-time" (OA-OT) protocol in the restoration of implants inserted in the anterior esthetic area. From January 2011 to January 2012, all consecutive patients requiring an implant n the maxillary area between canines were enrolled. After submerged healing and osseointegration, a definitive abutment with a provisional crown was inserted. After 1 month, the definitive crown was delivered (Tdef). Analog impressions were taken before tooth extraction (T0), at implant insertion Timpl, and Tdef, and at 12 months (T1) and 60 months (T5). Casts were scanned and superimposed using a dedicated software. Differences in vertical height of soft tissue margins between the digitized model casts were calculated and paired sample t test was conducted to compare results. To detect the potential role of biotype, groups (thick vs. thin) were compared by analysis of variance with general linear model. Twenty-five patients were enrolled. Three patients dropped out. At the 60-month, 22 patients (12 men and 10 women with mean age of 68.3 ± 11 years) concluded the study follow-up. Horizontal changes demonstrated gain of 1.06 mm at Timpl, 0.94 mm at Tdef, 0.92 mm at T1 and 0.97 mm at T5 compared to T0. Vertical changes demonstrated gain of 0.84 mm at Timpl, 0.11 mm at Tdef, 0.29 mm at T1 and 0.59 mm at T5 compared to T0. The analysis of variance showed a significant better performance of thick biotype in soft tissue horizontal width (P = .022). No statistical differences were noticed for vertical width (P = .111). The use of a conical abutment together with the OA-OT approach allowed longitudinal stable soft tissue dimensions.

Biomechanical effect of inclined implants in fixed prosthesis: strain and stress analysis

Abstract Introduction Implant inclinations can be corrected using mini abutments at different angulations. Objective To analyze the influence of external hexagon implants in different inclinations (3 levels) on the microstrain distribution generated around three implants. Method A geometric bone model was created through Rhinoceros CAD software (version 5.0 SR8, Mcneel North America, Seattle, WA, USA). Three implants (4.1 × 13 mm) were modeled and inserted inside the substrate at three different inclinations: 0º, 17º and 30º. Next, all groups received mini conical abutments, fixation screws and a simplified prosthesis. The final geometry was exported in STEP format to analysis software and all materials were considered homogeneous, isotropic and linearly elastic. An axial load (300N) was applied on the center of the prosthesis. An in vitro study was conducted with same conditions and groups for validating the tridimentional model. Result Stress was concentrated on the external area of the implants, in contact with the cortical bone and external hexagon. For the bone simulator, the strain increased in the peri-implant region according to the increase in the implant’s inclination. The difference between groups was significant (p = 0.000). The 30º group presented higher stress and strain concentration. Conclusion The microstrain and stress increase around implants directly proportional to the increase of the installation angle.

PD093: Clinical and patient related outcomes of a tapered implant system with switched platform conical abutments‐ a private practice field trial

PD093: Clinical and patient related outcomes of a tapered implant system with switched platform conical abutments‐ a private practice field trial

PR653: Performance of implants with internal conical abutment connection: 5‐year results of a two‐center prospective cohort study

PR653: Performance of implants with internal conical abutment connection: 5‐year results of a two‐center prospective cohort study

Clinical and Patient-Related Outcomes of a Tapered Implant System With Switched Platform Conical Abutments: A Private Practice Field Trial.

The aim of this prospective cohort observational field trial was to examine 1-year survival and success rates of a recently introduced tapered implant system with switched platform conical abutments and to evaluate patient related outcomes of therapy. Partially edentulous patients aged between 18 and 75 years, with available bone height for dental implants ≥10 mm desiring to restore the missing tooth/teeth with implant supported restoration, were recruited by 7 periodontists in their respective private practices. Dental implants were installed according to standard implant therapy protocol. Three to 6 months postoperatively, after evaluating interim implant success, implants were restored by the referring dentists. Patient, Ramfjord teeth, and implant data, including baseline and 1-year postoperative, were collected. A total of 60 patients were recruited and received 117 implants. Complete 1-year clinical and radiographic data were available for 83 and 65 implants, respectively. Two implants failed during the first year, resulting in a 1-year survival rate of 98.3%. Mean implant probing pocket depth was 2.29 ± 0.84 mm. Mean radiographic bone distance from implant's shoulder at the mesial and distal sites at 1 year was 0.66 ± 0.5 and 0.79 ± 0.64mm, respectively, resulting in a success rate of 95.4%. Patient subjective evaluation of therapy exhibited a median pain experience of 1 and median esthetics, function, and general satisfaction evaluation of 10 on a scale of 1 to 10. The tapered conical connection dental implant system, used in private dental practices, shows good 1-year survival and success rates that are similar to other implant systems on the market.

Influence of Abutment Surface Treatments on Screw Loosening of Morse Taper Implants.

To evaluate the effect of blasting and bonding on abutment surface to prevent screw loosening in Morse taper connections. Twenty-eight Morse taper connection implants were divided into 4 groups: no treatment (G1), blasting (G2), bonding (G3), and blasting + bonding (G4). In groups G2 and G4, the abutments were blasted with aluminum oxide granules; in groups G3 and G4, the conical abutment region was covered with a thin layer of bond thread lock agent. In all implants, the abutment-implant joint was tightened at a torque of 35 Ncm. The specimens were submitted to the mechanical cycling, under an oblique load for 1.0 × 10 cycles. The torque was measured with a digital torque meter. Data were analyzed by the t test, one-way analysis of variance, and Tukey tests (95%). The loosening strength was significantly higher in group G4 (35.83 ± 3.02 Ncm). There was no significant difference among groups G1 (25.86 ± 1.96 Ncm), G2 (25.86 ± 3.29 Ncm), and G3 (26.14 ± 2.12 Ncm). The association of blasting and bonding on abutment surface can be used to prevent screw loosening in Morse taper implants.

Implementation of computer-guided implant planning using digital scanning technology for restorations supported by conical abutments: A dental technique

Conometric retention has recently been proposed as an alternative to cement- or screw-retention for fixed restorations. Conometric copings can only compensate for slightly nonparallel placement without interfering with retention. This article describes a method of using digital scanning technology to facilitate computer-guided implant planning when an immediate restoration supported by conical abutments is planned with a guided-welded approach. The procedure involves importing the scan data of the conometric coping and of the definitive cast obtained from the surgical template into the implant planning software. This approach increases the accuracy of computer-guided implant planning and reduces the time needed for the surgery.

Immediately loaded implant-supported full-arches: Peri-implant status after 1–9 years in a private practice

ObjectiveEvaluate the peri-implant status on the long-term (1–9years) of patients treated with immediately-loaded full-arch prostheses in a private practice. MethodsA retrospective cohort study was carried out in patients consecutively treated with immediately loaded full-arch restorations supported with a minimum of 4 implants (Replace® Tapered, Nobel Biocare AB) and Multi-Unit conical abutments (MUA®, Nobel Biocare AB) with a follow-up of over 12months after placement of the final prosthesis. ResultsA total of 378 implants were placed in 56 patients. Forty upper and 32 lower arches were restored, and 16 patients received bimaxillary rehabilitation. The mean duration of follow-up was 50 months, and the implant and patient peri-implantitis prevalences were 14.3% and 50%, respectively. Mucositis affected 56.9% of the implants and 50% of the patients. The survival rate was 96.4% by patient, but reached 99.5% in the implant-based analysis, and the success rate was 95.5% for implants and 80.4% for patients. ConclusionsImmediately-loaded full-arch restorations have an acceptable outcome after 1–9years of follow-up. However, the incidence of peri-implant diseases is high, and further research is needed to confirm whether these may compromise the predictability of the prostheses over the long-term. Clinical significanceAfter a mean follow-up of 50months, the incidence of mucositis and peri-implantitis affected the 96.4% and 50% of patients, respectively. However, these results were reduced almost by half when the threshold of bleeding on probing and peri-implant bone loss applied was less strict.

Early Complications of Immediate Loading in Edentulous Full-Arch Restorations: A Retrospective Analysis of 88 Cases.

To describe the clinical outcomes and complications related to provisional prostheses after full-arch implant-supported rehabilitation by means of an immediate loading protocol. This retrospective cohort study included patients who were consecutively treated with full-arch implant-supported restorations with a minimum of four implants (Replace Select Tapered TiUnite, Nobel Biocare AB) per arch and conical abutments (multi-unit, Nobel Biocare AB) by means of an immediate loading protocol. The surgical procedures were performed between May 2006 and June 2014 by a single oral surgeon. Demographic, surgical, and prosthetic variables were collected, and biologic and mechanical complications were registered. A total of 61 maxillae (57%) and 46 mandibles (43%) were treated in 88 patients (40 men and 48 women) with a mean age of 62.4 years. A total of 558 implants were placed, 295 in postextraction sockets. A total of 331 implants (59.3%) were placed in the maxilla and 227 (40.7%) in the mandible. Within a 9-month period, 18 prostheses (16.8%) fractured (15 maxillary and 3 mandibular); in nine of these patients the opposing dentition was a full-arch, implant-supported restoration, and in the remaining nine patients, it was natural dentition. Six (1.1%) maxillary and three (0.5%) mandibular implants failed. A high implant survival rate is expected in the short term following this immediate loading protocol. Fracture of the provisional prosthesis is a common finding, affecting 17% of patients, and is significantly more prevalent in patients with bruxism and in maxillary prostheses.

Fracture Strength of Standard and Small Diameter Prosthetic Abutments for Full-Arch Implant-Supported Restorations.

This study tested the fracture strength of prosthetic abutments with different sizes and combinations to support a 5-implant milled framework with distal extension. Prosthetic abutments with different dimensions (4.8-mm diameter mini conical abutment and 3.5-mm diameter microconical abutment) were screwed to 5 threaded implants. The following groups were divided (n = 3): G1 with 5 miniconical abutments (standard size), G2 with 5 microconical abutments (small sized), G3 with a combination of 3 small sized abutments and 2 standard sized abutments, and G4 with a combination of 2 small sized abutments and 3 standard sized abutments. Standardized titanium frameworks for full-arch fixed dental prosthesis were milled with equidistant holes for each of the 5 implants and abutments. A loading point was selected at 18 mm away from both distal implants. A universal testing system was used for the fracture strength tests and load was applied at a crosshead speed of 0.5 mm/min on the previously described loading points until component fracture. Mean fracture strength for each group was statistically compared (α = 0.05). Prosthetic screws were the only fractured components for all tested groups. Mean fracture strength was: G1, 1130.22 N; G2, 1031.36 N; G3, 757.9 N; and G4 792.03 N (P < .05). All prosthetic abutments and combinations that were tested provide adequate fracture strength for clinical use. However, the combination of standard and small diameter abutments leads to lower fracture strength compared with when only standard sized prosthetic abutments were used, irrespective of the abutment diameter (4.8- or 3.5-mm).

Bimaxillary simultaneous immediate loading of full-arch restorations: A case series.

AimTo describe a bimaxillary simultaneous immediate loading protocol with full-arch implant-supported fixed prostheses.Material and MethodsA prospective case series of 8 patients who required full-arch rehabilitation was conducted. The main inclusion criteria were patients with teeth that required extraction. At least 1 molar per arch was temporarily employed to stabilize the surgical template and the provisional prosthesis during intraoral relining.ResultsTwo upper implants failed in 1 patient. Structural fracture was registered in 3 patients, around 3 months after loading. All of them had bruxism. Three esthetic complications were registered: midline deviation, canting of the oclusal plane and color mismatch.ConclusionsAlthough this protocol achieves optimal results, some mechanical complications were encountered. The fracture of the provisional prosthesis is a relatively common mechanical complication but does not seem to jeopardize the final treatment result. Key words:Implant-supported full-arch, provisional prosthesis fracture, bimaxillary simultaneous rehabilitation, conical abutments.

The Conometric Concept: Definitive Fixed Lithium Disilicate Restorations Supported by Conical Abutments.

The use of the conical coupling connection to support definitive restorations was evaluated in cases involving full acrylic resin or hybrid acrylic resin-composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with lithium disilicate and supported by coupling connection abutments and healed implants. The prostheses were placed in the posterior regions of partially edentulous patients; 65 patients received fixedlithium disilicate restorations splinted with conical coupling connectionsto two implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed after healing periods of 3 months: restorations were followed yearly for 3 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed at the last follow-up appointments. Two prostheses (3.07%) fractured: one was related to framework design error; one was caused by a car accident. Three patients reported small chips: these restorations were immediately polished. No significant difference involving peri-implant bone and probing levels between the experimental times were found. None of the prostheses became loose. The results of this research indicated that abutment-prostheses coupling connections were successful within the timeframe of this study.

Three-dimensional assessment of crestal bone levels at titanium implants with different abutment microstructures and insertion depths using micro-computed tomography.

To (i) assess the impact of insertion depth and abutment microstructure on the three-dimensional crestal bone-level changes at endosseous titanium implant using μCT and computerized image processing and (ii) to correlate the findings with previously reported histology. Titanium implants (conical abutment connection) were inserted in each hemimandible of n=6 foxhounds with the implant shoulder (IS) located either in epicrestal (0mm), supracrestal (+1mm) or subcrestal (-1mm) positions and randomly (split-mouth design) connected with machined or partially micro-grooved healing abutments. At 20weeks, the tissue biopsies were processed for μCT and histological (HI) analyses. The volumetric dehiscence profile around the implants was computed as distance between the implant shoulder (IS) and the most coronal bone-to-implant contact (CBI) using MATLAB. The respective buccal and oral values were averaged, and agreement with the respective IS-CBI scores from HI was assessed using Bland-Altman plots. A median net bone gain was observed for supracrestal insertion depths at both abutment types, but lower bounds of the 75% quartile experienced net bone losses. Epicrestal and subcrestal insertion depths were linked to slight bone losses, and the buccal and oral dehiscences were smaller compared to supracrestal positioning. Bland-Altman plots yielded a moderate agreement of IS-CBI values measured with μCT and HI. The novel image processing method allowed reliable evaluations and pointed to a direct impact of insertion depths on crestal bone-level changes. Additionally, it demonstrated that HI morphometry crucially depends on the chosen cutting position.

Arrangement of Peri-implant Connective Tissue Fibers Around Platform-Switching Implants with Conical Abutments and Its Relationship to the Underlying Bone: A Human Histologic Study

The objective of this study was to clarify and evaluate the orientation of the collagen fibers around platform-switching (PS) implants with conical abutments in humans after 8 weeks of healing, and to determine how this orientation would help stabilize the soft tissue and prevent bone resorption. On PS implants, circular orientation of collagen fiber was observed as the main arrangement in a cross-sectional view. The circular collagen fibers might be the key factor in stabilizing the soft tissues around the rehabilitation, inhibiting apical migration of the soft tissues and, in turn, protecting the underlying bone.