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Introduction: This in vitro study aims to biomechanically evaluate the influence of medium contamination for example, saliva, blood, chlorhexidine (liquid and gel), and fluoride mouthwash on the biomechanical behavior of implant abutments' screws under static and dynamic loading. Methods: Forty five Ti6Al4V commercial dental implants and abutments were tested in this study. Two main mechanical tests were carried out in the selected media. The first, static, aimed to evaluate the torque loss after the first tightening. The second, dynamic, involved a random cyclic load range between 0 and 200 N to evaluate torque loss due to mastication. In addition, metallographic longitudinal and cross‐sections of the abutment‐implant apparatus were examined to evaluate the abutment screw–abutment‐implant interface. Results: The static torque test showed that irrespective of the media, no statistical difference in static torque loss was found prior to dynamic loading. For the dynamic tests, torque‐angle evolution analysis during tightening to 30 Ncm and after the spectrum loading, showed the same global mechanical behavior for all media, but the statistical analysis indicated a difference between the groups in reverse torque values (RTV) and in the torque loss due to dynamic loading. The medium groups CHX, CHX‐gel, and Fluoride mouthwash, showed a meaningful torque loss due to loading, but the medium groups, control (no medium), blood and saliva showed an opposite trend and required a higher torque to open the abutment screws. The microstructural analysis revealed clear signs of cold‐welding/galling, post‐dynamic loading in these latter groups. Conclusions: The presence of lubrication/contamination media (CHX mouthwash/CHX‐gel/Fluoride mouthwash) reduces the preload generated due to tightening but prevents damage due to galling. The observed reduction of RTV clearly emphasizes the need for frequent abutment screw retightening for implant‐supported prosthetic long‐term stability. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK), a biomaterial with appropriate bone-like mechanical properties and excellent biocompatibility, is widely applied in cranio-maxillofacial and dental applications. However, the lack of antibacterial effect is an essential drawback of PEEK material and might lead to infection and osseointegration issues. This study aims to apply a natural antibacterial agent, totarol coating onto the 3D printed PEEK surface and find an optimized concentration with balanced cytocompatibility, osteogenesis, and antibacterial capability. In this study, a natural antibacterial agent, totarol, was applied as a coating to fused filament fabrication (FFF) 3D printed PEEK surfaces at a series of increasing concentrations (1 mg/ml, 5 mg/ml, 10 mg/ml, 15 mg/ml, and 20 mg/ml). The samples were then evaluated for cytocompatibility with L929 fibroblast and SAOS-2 osteoblast using live/dead staining and CCK-8 assay. The antibacterial capability was assessed by crystal violet staining, live/dead staining, and scanning electron microscopy (SEM) utilizing the oral primary colonizer S. gordonii and isolates of mixed oral bacteria in a stirring system simulating the oral environment. The appropriate safe working concentration for totarol coating is selected based on the results of the cytocompatibility and antibacterial test. Subsequently, the influence on osteogenic differentiation was evaluated by alkaline phosphatase (ALP) and alizarin red staining (ARS) analysis of pre-osteoblasts. Our results showed that the optimal concentration of totarol solution for promising antibacterial coating was approximately 10 mg/ml. Such surfaces could play an excellent antibacterial role by inducing a contact-killing effect with an inhibitory effect against biofilm development without affecting the healing of soft and hard tissues around FFF 3D printed PEEK implants or abutments. This study indicates that the totarol coated PEEK has an improved antibacterial effect with excellent biocompatibility providing great clinical potential as an orthopedic/dental implant/abutment material. [Display omitted] • A natural antibacterial coating of totarol was added on 3D-printed PEEK surfaces. • Different totarol concentrations led to varying biocompatibility and antibacterial effect. • A dynamic biofilm formation system was used to mimic the oral clinical environment. • The optimal coating concentration with balanced biocompatibility, osteogenesis and antibacterial efficacy was around 10 mg/ml. • Totarol coated PEEK shed light on a promising candidate for dental implants and abutments. [ABSTRACT FROM AUTHOR]

To compare retention strength of the polymethylmethacrylate (PMMA) crown and surfacepretreated PEEK abutment using various dental cements. Fifty PEEK abutments (PW plus Co., Ltd, Nakhon Pathom, Thailand) were pretreated with 90% sulfuric acid 60 seconds then cemented with milled Polymethylmethacrylate (PMMA) crown using various dental cements (Temp-Bond NE, Zinc phosphate, Panavia F2.0, RelyX U200 and Superbond C&B). After stored in 37ºC distilled water for 24 hours, the specimens were submitted to crown pull-off test using universal testing machine at crosshead speed 0.5 mm/minute. The retention strength (MPa) was calculated, and failure modes were recorded. All test groups were significantly different (p<0.05). Panavia F 2.0 presented the highest retention strength, followed by Temp-Bond NE. Zinc phosphate cement showed the lowest retention strength (p < 0.05). Superbond C&B and RelyX U200 could not acquire retention strength due to detachment of the abutment. Resin cement exhibited superior retention for PMMA crown and surface-pretreated PEEK abutment compared to Temp-Bond NE and Zinc phosphate cement. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate clinical performances of two lithium disilicate systems (Initial LiSi press vs Initial LiSi Block, GC Co.) using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after 4 years of clinical service. Methods: Partial adhesive crowns on natural abutment posterior teeth were made on 60 subjects who were randomly divided into two groups: Group 1: Initial LiSi press and Group 2. Initial LiSi Block. Fabrication of partial crowns was made with full analog and digital procedure in Groups 1 and 2 respectively. The restorations were followed-up for I and 4 years, and the modified USPHS evaluation was performed at baseline and each recall together with periodontal evaluation. Contingency tables to assess for significant differences of success over time in each group and time-dependent Cox regression to test for differences between the two groups were used and the level of significance was set at P< 0.05. Results: Regarding modified USPHS scores, all evaluated parameters showed Alpha or Bravo and no Charlie was recorded. No statistically significant difference emerged between the two groups in any of the assessed variables (P> 0.05). No statistically significant difference between scores recorded at the baseline and each recall. All modified USPHS scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired. and the survival rate was 100% after 4 years of clinical service. No difference was found between traditional and digital procedure to fabricate the crowns. The two lithium disilicate materials showed similar results after 4 years of clinical service. [ABSTRACT FROM AUTHOR]

Restorative dentistry is the repairing of damaged teeth and restoring oral health and function. Dental implants are typically placed within the cortical bone of the jaw to provide stability and support for prosthetic restorations. The successful restoration of complex anatomical features of the maxillary anterior is difficult for prosthodontists. Using a 3D slicer, CT scan images were used to create a detailed three-dimensional model of the maxilla bone. This study utilizes ANSYS Workbench, a finite element software program, to analyze the abutment angles, ranging from 0° to 25°, and the impact stress distribution within peri-implant bone. The outcomes of our studies align with and substantiate certain evidence in the literature documenting bone resorption, specifically at the level of the implant neck and near the cortical bone. The study aims to provide a comprehensive understanding of angled abutment stress patterns in the bone surrounding dental implants, offering valuable insights for clinical applications in critical areas of the mouth. [ABSTRACT FROM AUTHOR]

The arrangement of a stress breaker in the pier abutment of a fixed-mobile bridge affects the deformations that may occur in its supports. This article aims to study the most appropriate position and arrangement of a stress breaker. To verify the established objectives, an experimental "in vitro" study was carried out with five different bridge designs: one with rigid connectors and four with non-rigid connectors (interlocks), placed on the distal and mesial surface of the intermediate abutment, and combining the retention stop at cervical and occlusal positions. The strain level at the support ground of each bridge was measured with strain gauges. The statistical analysis was performed with the help of the Kruskal–Wallis test and a linear regression model. Initial results show that the model with the highest average value of maximum strain is the non-rigid bridge with the interlock on the distal surface of the pier abutment and the occlusal retention stop. In any case, the presence of an intermediate abutment, with or without interlock, influences the maximum tension supported by the abutment, especially in relation to the intermediate abutment. [ABSTRACT FROM AUTHOR]

The most challenging and time-consuming step in the free gingival graft (FGG) for keratinized mucosa augmentation is the compression suture anchoring the FGG to the periosteum. This article proposed a novel "microscrew with tie-down sutures" technique to anchor the FGG to the recipient site without the traditional trans-periosteum suture. This patient's keratinized mucosa width (KMW) around the healing abutments of teeth #29 and #30 was less than 1 mm. After an apically positioned flap (AFP) was prepared, 2 microscrews were placed at the buccal plate of the alveolar ridge bone, which is the coronal margin of the AFP. Then, the sutures winded between the microscrews and the healing abutments to anchor the FGG. In conclusion, the "microscrew with tie-down sutures" technique offers a feasible and straightforward alternative for the trans-periosteum compression suture, mainly when the periosteum is fragile, thin, or injured. [ABSTRACT FROM AUTHOR]

This study aims to analyse, using a finite element analysis, the effects of Ti-base abutment height on the distribution and magnitude of transferred load and the resulting bone microstrain in the bone-implant system. A three-dimensional bone model of the mandibular premolar section was created with an implant placed in a juxta-osseous position. Three prosthetic models were designed: a 1 mm-high titanium-base (Ti-base) abutment with an 8 mm-high cemented monolithic zirconia crown was designed for model A, a 2 mm-high Ti-base abutment with a 7 mm-high crown for model B, and a 3 mm-high abutment with a 6 mm-high crown for model C. A static load of 150 N was applied to the central fossa at a six-degree angle with respect to the axial axis of the implant to evaluate the magnitude and distribution of load transfer and microstrain. The results showed a trend towards a direct linear association between the increase in the height of the Ti-base abutments and the increase in the transferred stress and the resulting microstrain to both the prosthetic elements and the bone/implant system. An increase in transferred stress and deformation of all elements of the system, within physiological ranges, was observed as the size of the Ti-base abutment increased. [ABSTRACT FROM AUTHOR]

Re-tightening the loosened dental implant abutment screw is an accepted procedure, however the evidence that such screw will hold sufficiently is weak. The purpose of this study was material analysis of lost dental implant abutment screws made of the TiAlV alloy from various manufacturers, which became lost due to unscrewing or damaged when checking if unscrewed; undamaged screws could be safely re-tightened. Among 13 failed screws retrieved from 10 cases, 10 screws were removed due to untightening and 3 were broken but without mechanical damage at the threads. Advanced corrosion was found on nine screws after 2 years of working time on all surfaces, also not mechanically loaded. Sediments observed especially in the thread area did not affect the corrosion process because of no pit densification around sediments. Pitting corrosion visible in all long-used screws raises the question of whether the screws should be replaced after a certain period during service, even if they are well-tightened. This requires further research on the influence of the degree of corrosion on the loss of the load-bearing ability of the screw. [ABSTRACT FROM AUTHOR]

Aim: (1) To compare the temperature rise in the pulp chamber with different resin materials used for making provisional fixed partial dentures in anterior and posterior region while using Polyvinylsiloxane impression materials as matrix. (2) To identify a superior provisionalization material based on the amount of heat dissipated suitable for anterior and posterior provisional fixed partial denture fabrication. Settings and Design: Temporary crowns and bridges are integral to Fixed Prosthodontics. It has been observed that conventional fixed prosthesis temporisation materials release heat due to the exothermic polymerisation reaction. When such a provisional material is directly let to set on a vital tooth, the heat transfer causes irreversible changes in the pulp tissue depending of the degree of change. Hence, this study observes amount of heat generation in various materials during temporisation procedure, by simulating similar conditions. Materials and Methods: Two Models were fabricated, one simulating missing lateral incisor (Model A) and another simulating missing first molar (Model B). Intact maxillary central incisors and canine for Model A and intact mandibular Second Premolar and Second Molar were selected to act as abutments. These abutment teeth were fitted with the tip of a K-type Thermocouple inside their pulp chambers and these were connected to a digital thermometer. Five temporisation materials were chosen for fabrication of temporary crowns through Direct technique. (1) polymethy methacrylate (Self Cure acrylic), (2) bisacryl composite (Protemp 4), (3) visible light cure urethane dimethacrylate (Revotec LC), (4) barium glass and fumed silica infused methacrylate (Dentsply Integrity) and (5)nano-hybrid composite (VOCO Structur 3). Ten observations were made for each provisional material on each model. During each observation, temperature rise was recorded at 30s interval from the time of application, through the peak and till a decrease in temperature is observed. Polyvinyl siloxane was used as matrix for all except light cure resin, where polypropylene sheet was used. Statistical Analysis Used: Anova test used for statistical. Results: ANOVA test revealed that there was a significant difference in the temperature changes associated with the provisional restorative materials used. Among the five, polymethy methacrylate (self cure resin) showed the maximum rise in temperature, followed by bisacryl composite (Protemp 4), visible light cure urethane dimethacrylate (Revotec LC), barium glass and fumed silica infused methacrylate (Dentsply Integrity) and nano-hybrid composite (VOCO Structur 3). There was no comparable difference between Model A and B but an overall reduction of temperature rise was observed in model B. Conclusion: VOCO Structur 3 showed the least temperature rise in the pulp chamber, and overall temperature rise was less for model B which can be attributed to the residual dentin thickness. [ABSTRACT FROM AUTHOR]

This article discusses a study that evaluates the dimensions of micro-gaps at the implant-abutment connection in dental implant restorations. The study compares different types of implant abutments and measures the minimum and maximum distances between them. The results show that there are differences between the abutment types, but there are conflicting opinions in the literature regarding the superiority of original abutments. The study also examines the fit of CAD/CAM abutments compared to prefabricated abutments and finds that CAD/CAM abutments generally have a comparable fit. Another study analyzes the compatibility between different dental implants and non-original compatible stock abutments and finds that the vertical adaptations are within acceptable limits. The study concludes that CAD/CAM dental implant abutments provide similar results in terms of micro-gaps and could offer good adaptation and lower micro-gaps compared to stock abutments with proper quality control and modification of milling parameters. [Extracted from the article]

This article from the Romanian Journal of Oral Rehabilitation examines the effects of functional overload on the dental system. The study looks at changes in the periodontal tissues of both guinea pigs and patients, with the main cause of functional overload being the absence of teeth and poorly placed prostheses. The study highlights the importance of prosthetic treatment in preventing histomorphological changes caused by functional overload. The article provides data on the length of time patients have been without teeth and the corresponding damage to their oral cavity, including gingival lesions, poorly constructed prostheses, and periodontitis. The document also discusses the microscopic and macroscopic changes observed in patients and animals, as well as the correlation between the length of time without teeth and the atrophy of the alveolar process. The conclusion emphasizes the importance of addressing tooth loss through therapeutic-prosthetic procedures to minimize damage to the stomatognathic apparatus. [Extracted from the article]

Copyright of Implantologie is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Implantologie is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Implantologie is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: The stability of implant-abutment connection is crucial to minimize mechanical and biological complications. Therefore, an assessment of the microgap behavior and abutment displacement in different implant-abutment designs was performed. Methods: Four implant systems were tested, three with a conical implant-abutment connection based on friction fit and a cone angle < 12 ° (Medentika, Medentis, NobelActive) and a system with an angulated connection (< 40°) (Semados). In different static loading conditions (30 N − 90º, 100 N − 90º, 200 N − 30º) the microgap and abutment displacement was evaluated using synchrotron-based microtomography and phase-contrast radioscopy with numerical forward simulation of the optical Fresnel propagation yielding an accuracy down to 0.1 μm. Results: Microgaps were present in all implant systems prior to loading (0.15–9 μm). Values increased with mounting force and angle up to 40.5 μm at an off axis loading of 100 N in a 90° angle. Conclusions: In contrast to the implant-abutment connection with a large cone angle (45°), the conical connections based on a friction fit (small cone angles with < 12°) demonstrated an abutment displacement which resulted in a deformation of the outer implant wall. The design of the implant-abutment connection seems to be crucial for the force distribution on the implant wall which might influence peri-implant bone stability. [ABSTRACT FROM AUTHOR]

Background: While the concept of angled screw channels has gained popularity, there remains a scarcity of research concerning the torque loss and fracture strength of monolithic zirconia restorations with various screw channel angulations when exposed to thermomechanical cycling. This in-vitro study aimed to evaluate the reverse torque value and fracture resistance of one-piece screw-retained hybrid monolithic zirconia restorations with angulated screw channels after thermomechanical cycling. Methods: One-piece monolithic zirconia restorations, with angulated screw channels set at 0°, 15°, and 25° (n = 6 per angulation) were fabricated and bonded to titanium inserts using a dual-cure adhesive resin cement. These assemblies were then screwed to implant fixtures embedded in acrylic resin using an omnigrip screwdriver, and reverse torque values were recorded before and after thermomechanical cycles. Additionally, fracture modes were assessed subsequent to the application of compressive load. One-way ANOVA and Bonferroni post hoc test were used to compare the groups (α = 0.05). Results: The study groups were significantly different regarding the fracture resistance (P = 0.0015), but only insignificantly different in the mean percentage torque loss (P = 0.4400). Specifically, the fracture resistance of the 15° group was insignificantly higher compared to the 0° group (P = 0.9037), but significantly higher compared to the 25° group (P = 0.0051). Furthermore, the fracture resistance of the 0° group was significantly higher than that of the 25° group (P = 0.0114). Conclusions: One-piece hybrid monolithic zirconia restorations with angulated screw channels can be considered an acceptable choice for angulated implants in esthetic areas, providing satisfactory fracture strength and torque loss. [ABSTRACT FROM AUTHOR]

Objectives: To compare the crown accuracy and time efficiency of a complete digital workflow, utilizing an auxiliary occlusal device and IO scanning, with a conventional workflow, for multiple implant-supported single crowns. Materials and methods: 24 patients with two adjacent posterior implants were included. 12 patients were randomly assigned to digital workflow group, involving intra-oral scanning with an auxiliary occlusal device and manufacture of customized abutments and zirconia single crowns (test group). The other 12 were assigned to the conventional workflow (control group), involving conventional impression and CAD-CAM crowns based on stone casts. Crown scanning was done before and after clinical adjustment using an intraoral scanner. Two 3D digital models were overlapped to assess dimension changes. Chair-side and laboratory times for the entire workflow were recorded and a linear mixed model and Independent-sample t tests were used for the statistical analysis. Results: The maximum occlusal deviation was 279.67 ± 112.17 μm and 479.59 ± 203.63 μm in the test and control group, respectively (p < 0.001). The sizes of the occlusion adjustment areas were 12.12 ± 10.51 mm2 and 25.12 ± 14.14 mm2 in the test and control groups, respectively (p = 0.013). The mean laboratory time was 46.08 ± 5.45 and 105.92 ± 6.10 min in the test and control groups, respectively (p < 0.001).The proximal contact adjustment and mean chair-side time showed no statistically significant difference between two groups. Conclusions: A digital workflow for two implants-supported single crowns using an auxiliary device required fewer occlusal crown adjustments, and less laboratory time compared to conventional workflow. Clinical Relevance: The use of auxiliary occlusal devices in IOS enhances the accuracy of virtual maxillomandibular relationship in extended edentulous spans. Consequently, employing a digital workflow for multiple implants-supported crowns using IO scanning and an auxiliary occlusal device proves to be a feasible, accurate and efficient approach. [ABSTRACT FROM AUTHOR]

Purpose: Despite the differences in material properties and shapes among the different types of prefabricated titanium (pTiA) and individualized hybrid zirconia abutments (ihZiA), the biological and clinical relevance of materials and construction features remains vague. Yet, individualized ihZiA are increasingly implemented into daily routine aiming to satisfy rising expectations. The objective was to compare these two types of abutments in fixed dental prostheses (FDP). Methods: This cross-sectional study examined 462 implants in 102 patients comparing pTiA (52 patients) to ihZiA (50 patients) for FDP. These different treatment regimens were evaluated in terms of peri-implant health, radiographic bone loss, and oral-health related quality of life (OH-QoL) with special consideration of abutment type and superstructure design. Results: ihZiA showed significantly different design features than prefabricated pTiA, but the annual bone loss in both groups did not. Visible titanium in the esthetic zone negatively impacted OHIP 14 scores. The combination of an emergence angle (EA) of < 30° and a concave emergence profile (EP) as well as gingiva thickness (p = 0.002) at the time of the prosthetic restoration significantly improved the annual peri-implant bone loss, independently of the abutment type. Conclusion: ihZiA showed comparable results to pTiA. To optimize the long-term outcome, not just material alone but generating adequate soft tissue thickness, minimizing the EA, and applying a concave EP seem to be the most relevant factors. To improve OH-QoL, particular attention must be paid to the esthetic zone. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of two coating materials, a silicone sealing gel and a polytetrafluoroethylene (PTFE) tape, on the screw preload and removal torque value (RTV) to develop strategies to prevent prosthetic screw loosening. We examined 45 complexes comprising an implant, abutment, and prosthetic screw, of which 15 samples were uncoated, 15 were coated with GapSeal® (Hager & Werken GmbH & Co., Duisburg, Germany), and 15 were coated with PTFE tape (MIARCO®, Valencia, Spain). The screws were tightened to register the preload and then untightened to register the RTV. The preload values showed a statistically significant difference only in the PTFE group, suggesting that this lubricant negatively affects the preload. The RTVs showed statistically significant differences among all groups, with the GapSeal® group and PTFE group showing the highest and lowest values, respectively. It can be concluded that the application of the PTFE tape on the screw significantly reduced the preload and RTV. The silicone sealing gel did not affect the preload but increased the RTV. Therefore, the use of GapSeal® should be considered to prevent prosthetic screw loosening, while the use of PTFE tape should be avoided. [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to investigate, through finite element analysis (FEA), the biomechanical behavior of the built-in angle corrected dental implant versus implant with angled multiunit abutment used in All-On-Four treatment protocol. Methods: Two (3D) finite element models of a simplified edentulous mandible were constructed with two different posterior implant designs based on the All-On-Four protocol. Four implants were placed in each model, the two anterior implants were positioned vertically at the lateral incisor/canine sites. Depending on the implant fixture design in posterior area, there are two models created; Model I; the mandible was rehabilitated with four co-axis (4 mm in diameter × 15 mm in length) implants with distally built-in angle corrected implants (24-degree angle correction).While Model II, the mandible was rehabilitated with four conventional (4 mm in diameter × 14 mm in length) implants with a distally inclined posterior implants (25 degree) and angled multiunit abutments. CAD software (Solidworks© 2017; Dassault Systems Solidworks Corp) was used to model the desired geometry. Axial and inclined Loads were applied on the two models. A Finite element analysis study was done using an efficient software ANSYS© with specified materials. The resultant equivalent Von-Misses stresses (VMS), maximum principal stresses and deformation analysis were calculated for each part (implants and prosthetic components). Results: When applying axial and non-axial forces, model II (angled multiunit model) showed higher deformation on the level of Ti mesh about 13.286 μm and higher VMS 246.68 MPa than model I (angle corrected implant). Model I exhibited higher maximum stresses 107.83 MPa than Model II 94.988 MPa but the difference was not statistically significant. Conclusion: Within the limitation of the FEA study, although angle correcting implant design is showing higher values in maximum principle stresses compared with angled multiunit abutments, model deformation and resultant VMS increased with angled multiunit abutments. The angle correcting designs at implant level have more promising results in terms of deformation and VMS distribution than angle correction at abutment level. [ABSTRACT FROM AUTHOR]

Support and stability for a Removable Partial Denture (RPD) are difficult to achieve in a distal extension edentulous ridge and are even more compromised in reduced dentition. The combination of the altered cast technique and milled crown in removable partial denture fabrication would greatly enhance support by redistributing the load more effectively. However, it is not routinely practiced due to the complexity of the treatment and the lack of emphasis in dental curriculum. In the present case of a 54-year-old male, despite several attempts at wearing the denture, the patient was unable to tolerate it. The atrophic mandibular ridge and poor inclination of the abutment tooth seemed to be complicating factors. Therefore, the prosthesis required some modifications. The present case report highlights the Applegate altered cast technique, which can be deployed with a milled crown, including the clinical and laboratory stages involved. This might help to overcome the problems encountered with distal end saddle dentures, making them more tolerable to patients. [ABSTRACT FROM AUTHOR]

Digital technology has been applied to the planning and manufacture of removable partial dentures (RPDs), reducing the complexity of RPD treatment as well as the number and duration of clinical and laboratory steps. However, there is a lack of information regarding digital planning and surveying for rotational path RPDs. This article presents a case report of a digital diagnostic wax-up and survey for a rotational path RPD performed with prosthetic design software. The virtual diagnostic closure tool made it possible during the case study stage to visualize the edentulous spaces and simulate the preparations necessary for the restoration of occlusal and esthetic harmony. The virtual survey determined the dual-axis path of insertion and removal for the rotational path RPD based on the 4 major influencing factors: guiding planes, retentive undercuts, interferences, and esthetics. In this case, digital planning and surveying for a rotational path RPD were an effective means of esthetic and biomechanical analysis and allowed for minimal preparation of the abutment teeth. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the influence of abutment material, alveolar bone density, and occlusal forces on stress distribution around maxillary anterior implants. Materials and Methods: An in-vitro study was conducted. The maxillary anterior implant was modeled using a three-dimensional finite element model in D2 and D3 bones with three different abutment materials: titanium, zirconia, and poly-ether-ether ketone (PEEK). Von Mises stress was evaluated after the application of vertical and oblique loads of 100 N, 175 N, and 250 N. Statistical analysis was done by Friedman--Wilcoxon signed-rank test, Mann--Whitney U test, and Kruskal-- Wallis test. The probability value <0.05 is considered a significant level. Results: Stress distribution around D3 bone was higher than D2 bone in all the abutment materials with greater values seen in oblique load than vertical load with insignificant difference (P > 0.05). Statistically insignificant stress values were seen greater in PEEK than titanium or zirconia abutment (P > 0.05). A statistically significant difference was observed between 100 N and 175 N of load (P < 0.05). Conclusion: PEEK, zirconia, and titanium as abutment material in the anterior region showed similar properties. The stress on the bone was proportionately increased during the vertical and oblique loads suggesting the influence of mechanical load in crestal bone loss rather than the type of abutment material. [ABSTRACT FROM AUTHOR]

The biomaterials applicable in dental implantology, or implantology generally, are subject to specific requirements, namely biocompatibility, osseointegration, resistance to fracture/oxidative degradation/long-term compressive stress/hydrolisis in boiling water, suitable morphology, suitable physical properties (including mechanical properties), aesthetics, etc. When selecting a suitable material for dental implants, it is also necessary to consider the patient's current health condition and possible complications when placing titanium implants and alloys. If there is a risk of an allergic reaction or hypersensitivity to any of the components of the metal prosthesis, the placement of a semicrystalline thermoplastic implant - called polyetheretherketone, abbreviated PEEK - is a possible option. Such a wide range of stiffness means that PEEK formulations can be produced with modulus values similar to cortical bone. PEEK is classified as a High Performance Polymer of polymer pyramide (such as Polysulfones polybutylene terephthalate). PEEK can be applied for dental abutment and dental body. This article summarises basic information on the structure and properties of PEEK polymer, advantages/disadvantages (compared to metal - titanium restorations), application and general information from the examined field. [ABSTRACT FROM AUTHOR]

Background. The widespread use of dental implants as a predictable treatment choice has drawn attention to their complications as a major challenge despite their high clinical success rates. In this context, loosening of the abutment screw in posterior single crowns is the most common problem; the use of adequate preload and proper anti-rotational features at implant?abutment interface appear to be two main solutions to such a problem. The present study evaluated the effect of implant?abutment connections in four different implant systems before and after cyclic loading. Methods. Intra-Lock, Dentis, Xive, and Dio implant systems were used in this study. Each system underwent one million cycles of dynamic forces eight times with a magnitude of 110 N. For each specimen after tightening the screw with a torque of 32 Ncm, the detorque values were measured and recorded by a digital torquemeter after and before cyclic loading. Data were analyzed by Kolmogorov-Smirnov, Levene's, one-way ANOVA, and post hoc Tukey tests. Results. Initial detorque values between the study groups showed significant differences (P < 0.0001). Pairwise comparisons showed significantly lower primary detorque values in the Dentis system compared to the three other systems (P < 0.0001). After cyclic loading, significant differences were observed between the study groups (P < 0.0001). Pairwise comparisons of the groups showed significant differences between all the systems after loading. Conclusion. The type of implant?abutment connection is an essential factor influencing the amount of abutment screw loosening. [ABSTRACT FROM AUTHOR]

Abstract Objectives The stability of the abutment screw is pivotal for successful implant‐supported restorations, yet screw loosening remains a common complication, leading to compromised function and potential implant failure. This study aims to evaluate the effect of different implant‐abutment types and heights on screw loosening in cases with increased crown height space (CHS). Materials and Methods In this in vitro study, a total of 64 abutments in eight distinct groups based on their type and height were evaluated. These groups included stock, cast, and milled abutments with heights of 4 mm (groups S4, C4, and M4), 7 mm (groups S7, C7, and M7), and 10 mm (groups C10 and M10). Removal torque loss (RTL) was assessed both before and after subjecting the abutments to dynamic cyclic loading. Additionally, the differences between initial RTL and RTL following cyclic loading were analyzed for each group (p

Purpose: Titanium-zirconium (Ti-Zr) alloy has been developed to strengthen the implant body, but clinically relevant information is still limited. The aim of this in vitro study was to compare the rotational load fatigue performance of implantabutment connections in narrow-diameter (3.3-mm) and regular-diameter (4.1-mm) implants made with commercially pure grade 4 titanium alloy (CPTi-G4) and Ti-Zr. Materials and Methods: Narrow-diameter (N) and regular-diameter (R) implants with CPTi-G4 (Ti) or Ti-Zr (Tz) materials were tested. This resulted in four test groups: NTi, NTz, RTi and RTz. Five specimens were made for each group (n = 5). Abutments used were milled from titanium-aluminum-niobium alloy abutment blanks. A rotational load fatigue machine applied a sinusoidally varying load at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz in air at 20°C. The number of cycles to failure was recorded. The upper limit was set as 5 million cycles. Results were evaluated using analysis of variance (ANOVA) and Tukey post hoc tests. Failure locations and patterns were evaluated with scanning electron microscope (SEM). Results: All regular-diameter test groups reached the upper limit of 5 million cycles without failure. All narrow-diameter test groups failed within the range of 402,530 cycles to 3,374,353 cycles. It could be observed that NTz showed a higher mean cycle count as compared to NTi. NTi test group recorded two implants damaged, one implant fracture, five abutment fractures, and four screw fractures. NTz test group showed only abutment fractures at the level of implant platform, with no damage to the implant bodies. Significant difference was found between implants of different diameters. There was no significant difference between implants of different materials. Conclusion: Regular-diameter implants performed significantly better than narrow-diameter implants, regardless of material, while no significant difference in cyclic load to failure was found between groups of different alloys. All NTz failures were at the abutment only, without damage to the implant. This failure pattern can potentially be clinically advantageous in terms of retrieval and subsequent replacement of a failed prosthesis. [ABSTRACT FROM AUTHOR]

Purpose: To examine the stress distribution in the maxillary All-on-4 treatment concept supported by implants of different diameters under two different loading forces using finite element analysis. Materials and Methods: Two distinct All-on-4 designs were prepared in a fully edentulous maxilla, supported by 3.3- and 4.1-mm-diameter implants. Posterior implants were tilted distally, approximately 30 degrees to the occlusal plane, and anterior implants were placed axially. Bone, implant, and prosthetic components were modeled separately and were tightly connected to each other. Under two distinct loading conditions representing the occlusal forces of healthy and bruxist individuals, the stresses on peri-implant bone, implant, and prosthetic components were evaluated using finite element analysis. Results: There were higher stresses on cortical bone than on trabecular bone. The stresses on bone and implant components were concentrated around the posterior implants, whereas stresses on the prosthesis were concentrated anteriorly. With increasing implant diameter, the stresses on trabecular bone, abutments, and crowns increased, whereas the stresses on cortical bone, implants, and frameworks decreased. Compressive stresses in the cortical bone and von Mises stresses in the frameworks exceeded the overload limit in both models under bruxist loading. Conclusion: The stresses on the cortical bone, implants, and frameworks were slightly higher in the model with 3.3-mm-diameter implants, whereas the stresses on the trabecular bone, abutments, and crowns were slightly higher in the model with 4.1-mm-diameter implants. [ABSTRACT FROM AUTHOR]

Purpose: To compare the fracture resistance of a press-on ceramic custom implant restoration with pressed and cemented restorations. Materials and Methods: Thirty-two (32) lithium disilicate (IPS e.max Press) custom hybrid abutment restorations were fabricated. The restorations were divided into two groups (n = 16) according to the construction technique: the commercial control group (C) and the press-on group (P). For the control group, lithium disilicate restorations were pressed and cemented on titanium bases. For the press-on group, lithium disilicate pressable ceramic (IPS e.max Press) was pressed on the titanium bases with injection molding. Each group was further divided according to the restoration design, either screw-or cement-retained, into two subgroups of eight specimens each. Specimens of C group were divided into screw-retained (cemented hybrid abutment crown, CHAC) or cement-retained (cemented hybrid abutment, CHA). Specimens of the P group were also divided into screw-retained (pressed hybrid abutment crown, PHAC) and cement-retained (pressed hybrid abutment, PHA). The specimens were subjected to static loading until failure with a universal testing machine. Two-way analysis of variance (ANOVA) was used to assess the effect of different techniques and designs on the fracture resistance of the samples (P < .05), followed by one-way ANOVA and Tukey honest significant difference (HSD) test (a = .05). Results: C group showed higher mean fracture resistance (812.443 ± 129.14 N) than P group (596.71 ± 108.83 N), and the difference was statistically significant (P < .05). Regarding restoration design, HA groups showed higher mean fracture resistance (742.621 ± 153.82 N) than HAC (666.53 ± 163.07 N) groups with no statistically significant difference. CHA showed the highest mean fracture resistance (817.65 ± 161.76 N), while PHAC showed the lowest mean fracture resistance values (525.83 ± 47.29 N). Conclusion: The commercial cemented lithium disilicate restorations showed higher fracture resistance than the press-on restorations, although both showed a maximum load capacity that was greater than physiologic incisal force in the anterior region, and both hybrid abutments and hybrid abutment crowns were equally efficient in withstanding occlusal loading forces. [ABSTRACT FROM AUTHOR]

Prosthetic design is a critical step in implant treatment planning that must synchronize with implant positioning to promote a state of peri-implant health. Improperly designed prostheses may not only hinder patient (or professional) hygiene measures but also impact the ability of clinicians to examine the peri-implant supporting tissues for diagnostic purposes. The purpose of this review was to discuss the current state of the evidence surrounding prosthetic factors associated with peri-implant diseases. Following the chronologic order of implant treatment, key prosthetic variables were discussed in relation to peri-implant disease pathogenesis. Specific concepts including the impact of implant spatial positioning, abutment height, residual cement, and implant splinting were found to be associated with peri-implant disease pathogenesis. Excessive occlusal forces were found to play a role in susceptibility to prosthetic complications with limited evidence to suggest a role in peri-implant disease progression. An intimate prosthetic-biologic connection exists, which must be respected to promote an environment for long-term peri-implant stability and health. [ABSTRACT FROM AUTHOR]

Purpose: This review aimed to summarize the current literature on the oral biofilm formation on alternative abutment materials compared with titanium (Ti) or Ti alloy in clinical and in situ conditions. Materials and Methods: An electronic database search was conducted in PubMed, Cochrane Library, EMBASE, Scopus, Web of Science, LIVIVO, BVS, ProQuest, and OpenGrey up to November 2020. Clinical and in situ studies evaluating the biofilm formed on metallic, ceramic, or polymeric abutment materials compared with Ti or Ti alloy were included. Outcome measures were microbial counts/profile, cell viability, and biofilm coverage/thickness. Clinical parameters were deemed secondary outcomes. Risk of bias was assessed by RoB 2 and ROBINS-I tools. Results: A total of 10 clinical and 9 in situ studies were included. Meta-analysis was not performed due to heterogeneity across studies. The abutment materials polytetrafluoroethylene, gold alloy, gold-platinum alloy, cobalt-chromium, alumina, and zirconia were reported. Six out of ten clinical studies (60%) and four out of nine in situ studies (44%) found no qualitative or quantitative microbiologic differences between tested materials. When significant differences were detected, conflicting results were reported. Clinical outcomes were consistent with healthy conditions for all investigated materials. Conclusion: There is not enough evidence to support the existence of relevant microbiologic differences in the biofilm formed on alternative abutment materials over Ti and its alloys in oral conditions. No evident relationship between microbiologic results and clinical outcomes were found. In situ studies and polymicrobial analyses showed a higher tendency to find significant differences between materials. [ABSTRACT FROM AUTHOR]

Objective: To describe a procedure that uses a definitive BioHPP hybrid abutment (polyether ether ketone [PEEK] reinforced with ceramic nanoparticles), to obtain a hermetic mucous seal with the peri-implant soft tissues. Method and materials: Between July 2017 and December 2019, seven patients aged between 40 and 60 years, who needed prosthetic rehabilitation in the esthetic zone, were treated. Among the various therapeutic solutions offered, patients chose an immediate or conventional implant rehabilitation using the “one abutment– one time” technique with the hybrid SKY elegance implant abutment (bredent medical). Ten implants were placed, five with immediate loading including two postextraction, and five in a conventional/classic loading protocol. The protocol required that the finishing margin of the provisional restoration was positioned approximately 1 to 2 mm from the implant platform, allowing the tissues to heal around the ceramic-reinforced PEEK abutment. After 6 months for the implants with immediate loading, and 3 months for those with conventional loading, the provisional restorations were replaced with definitive zirconiaceramic prostheses. Results: The clinical evaluation on the 10 implants showed that the reinforced PEEK abutments integrated well with the peri-implant tissues, and were healthy, without plaque, and with no bleeding on probing. An average probing depth of 1.0 mm was observed for nine of the ten placed implants, and for the tenth the implant probing depth was 1.5 mm. Conclusions: The ceramic-reinforced PEEK abutments BioHPP SKY elegance associated with the one-time therapeutic protocol is a valid alternative to traditional implant loading procedures, leading to an effective peri-implant hermetic mucous seal. [ABSTRACT FROM AUTHOR]

Purpose: To compare the retention forces of implant overdenture patrices (ball, bar, and TiSi.snap) to conventional (O-ring, metal housing, and clip) and polyvinyl siloxane (PVS)-based silicone (retention.sil 200, 400, and 600; Mucopren Soft; and GC Reline Soft) matrix materials.Materials and Methods: Two implant analogs, in which the patrices were to be placed, were embedded parallel to each other in polyethylene blocks, and the matrices were placed in heatpolymerized acrylic blocks that were fabricated as overdentures. Ten samples were prepared for each attachment type, and 180 samples were obtained from 18 groups. All samples were placed in a chewing simulator for occlusal force application and for insertion and removal of the pieces. Retention measurements were performed with a universal testing device at the initial (10 cycles), simulated first-year (1,825 cycles), and simulated second-year (3,650 cycles) periods, assuming that the patients would insert and remove their overdenture five times daily.Results: Loss of retention occurred in all the attachment systems at the end of 3,650 cycles (P < .05). The PVS matrix materials showed less retention than the O-ring and metal matrices when a ball patrix was used, while they had higher retention than bar clips when the Hader bar patrix was used (P < .05). Among the PVS matrix materials, retention.sil 200 produced the lowest retention values, whereas retention.sil 600 generated the highest.Conclusion: PVS matrix materials show higher retention than that achieved by yellow plastic bar matrices. However, these materials exhibit lower retention than with plastic and metal matrices of ball abutments. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the survival of implants and abutments and the incidence of mechanical complications of single posterior implant-supported restorations using prefabricated titanium abutments. Materials and Methods: This retrospective clinical study analyzed 172 Astra Tech OsseoSpeed internal hexagon implants (Dentsply Sirona) placed in 85 patients with a follow-up between January 2009 and January 2019. All implants were restored with prefabricated titanium abutments and cement-retained metal-ceramic crowns. The clinical outcomes recorded were implant and abutment survival rates and mechanical complications (abutment/implant fractures, screw loosening/fracture, decementation of the superstructure, veneer chipping/fractures) and were analyzed according to age, sex, implant length/diameter, bone graft, arch, implant position, parafunctional habit or dental status, and opposite arch. Kaplan-Meier survival analysis was used to determine whether the distribution of time to event/failure differed based on implant position (premolar or molar), implant diameter, or abutment angulation. Results: During the observation period (mean: 108 months), implant and abutment cumulative survival rates were 97.7% and 98.3%, respectively, with no statistically significant differences between implant positions (molar/premolar), implant diameters (3.5 vs 4 mm), or abutment angles (straight vs 15 degrees). Of the 172 single posterior implant-supported restorations, 14 mechanical complications (8.2%) were recorded. In particular, 3 abutment fractures (1.7%), 2 screw loosenings (1.2%), 2 screw fractures (1.2%), 1 implant fracture (0.6%), 2 chipping/fractures of veneering materials (1.2%), and 4 decementations of the superstructure (2.3%) occurred. Conclusion: The single posterior implant-supported restorations using prefabricated titanium abutments remain a clinically acceptable treatment in terms of prosthetic procedure and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Purpose: The objectives of this in vitro study were to evaluate changes in the retention force of the indexed conometric system subjected to repeated insertion-removal cycles and to examine the elements (matrix and patrix) that cause retention changes in the system as a result of repeated cycles. Materials and Methods: Monolithic zirconia crowns were cemented on 24 matrixes and 24 patrixes fixed on the implant analog. The pull-out test was performed with 12 matrixes and 12 patrixes attached, and the initial retention forces were recorded. Six of them were subjected to five insertion-removal cycles (5-cycle group), and the other six samples to 15 cycles (15-cycle group), and the final retention forces were calculated. Then, in both groups, an element of each pair exposed to the cycle was matched by an exchanging with new pieces: 5 cycles of matrix--new patrix (5M/0P), 5 cycles of patrix--new matrix (5P/0M), 15 cycles of matrix--new patrix (15M/0P), and 15 cycles of patrix--new matrix (15P/0M); thus, subgroups were created. A pull-out test was applied to these subgroups, and retention forces were recorded. Data were subjected to a paired-samples t test (α = .05). Two specimens from the 15-cycle group were randomly selected and analyzed by scanning electron microscopy. Results: In the 5-cycle group, the mean initial retention force was 153.13 ± 7.08 N, and the mean final retention force was 111.59 ± 18.30 N. In the 15-cycle group, the mean initial retention force was 143.30 ± 15.46 N, and the mean final retention force was 78.55 ± 17.03 N. There was a statistically significant loss of retention in both groups (P < .05). The change in retention in the 5P/0M and 15P/0M subgroups was not statistically significant (P > .05). However, significant loss of retention was found in the 5M/0P and 15M/0P subgroups (P < .05). Conclusion: There was a significant loss of the retention force after insertion-removal cycles. The increase in these cycles caused a further decrease in retention force. The decrease in the retention force of this system mainly resulted from the changes in the surface characteristic of the frictional surfaces of the matrix. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effects of vertical compressive cyclic load on abutment screws and the stability of screw-retained splinted fixed dental prostheses supported by bone-level nonengaging and partially engaging abutments. Materials and Methods: Ten standardized two-unit prostheses integrated with nonengaging and partially engaging abutments were 3D-printed and cast in nonprecious metal and attached to two implant analogs with conical connections angled 15 degrees toward the vertical axis in a resin bock. The common path of insertion for the prosthesis with partially engaging abutments to angled implant analogs was created by selectively reducing the abutment surface that obstructed the implant housing. A 500-N average load was applied to each sample while oscillating 30 degrees from the vertical axis at 60 Hz to failure. Prosthesis stability was measured by deflection from the initial position using a linear displacement measuring device. Sample groups were assessed using the independent-samples t test and one-way repeated-measures analysis of variance (ANOVA) with post hoc tests. Results: The mean cycles to failure for nonengaging and partially engaging abutment groups were 27,180 ± 29,420 and 457,890 ± 265,734, respectively. Failed nonengaging samples had 9 out of 10 abutment screws fracture inside the implant housing but with minimal wear to the top of the implant analog. For partially engaging samples, 8 out of 10 implant housings and 7 out of 10 abutment screws fractured at test endpoints. There was no difference in initial deflections between groups. Prostheses supported by nonengaging abutments failed before deflection measurements could be taken after loading. Prosthesis displacement of partially engaged abutments decreased significantly from the initial position after 300,000 load cycles. Conclusion: Under the experimental conditions, screw-retained splinted fixed dental prostheses supported by partially engaging abutments are 17 times more stable than prostheses supported by nonengaging abutments. Abutment screw fractures are the most prevalent mode of failure for nonengaging abutments at significantly lower cycles with minimal wear on implant analogs. Partially engaging abutment groups failed from implant housing and abutment screw fractures at higher cycles. Loading appears to concentrate preferentially on the medial side on all angled implant components. Selective removal of the abutment obstruction allows a common path of insertion for multiple implants and partial engagement to implant housings. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were: (1) to quantify the marginal bone loss (MBL) of 3.3-mm narrow-diameter, bone-level, titanium-zirconia (Ti-Zr) implants with two different surfaces in single restorations after a 1-year follow-up; (2) to analyze the combinations of different variables that may influence MBL; and (3) to record the Pink Esthetic Score (PES) value and its correlation with MBL. Materials and Methods: This is a prospective longitudinal clinical study with a 1-year follow-up after crown placement. Two different implant surfaces (sandblasted acid-etched and modified sandblasted acid-etched) were used. All bone-level and bone level--tapered implants had a diameter of 3.3 mm. Different healing and prosthetic abutments were used. Clinical, radiographic, and photographic records were taken 6 months and 1 year after placement of the restorations, and the survival rate, MBL, PES, clinical parameters, and biologic and/or mechanical complications were assessed. The correlations between the variables and MBL were verified. Results: A total of 30 narrow-diameter implants were placed in 30 patients; 18 implants had a sandblasted acid-etched surface, and 12 implants had a modified sandblasted acid-etched surface. The measured MBL at 1 year after implant function had a mean value of -0.36 mm, ranging from 0 mm to -1.77 mm. There was no implant loss. A statistically significant relationship was observed between implant shape (design and length), implant placement level, healing abutment, prosthetic abutment size, gingival thickness, and MBL. The mean PES values recorded at the beginning and end of the study were 7.58 and 11.37, respectively. Conclusion: Narrow-diameter implants showed reduced MBL values, with the surrounding tissues remaining stable after 1 year of follow-up. The MBL did not show different values on two implant surfaces. MBL does not seem to influence esthetic outcome. [ABSTRACT FROM AUTHOR]

Purpose: To determine the fracture strength and stress distribution of esthetic dental implant abutments. Materials and Methods: Fifty specimens were prepared. Four hybrid abutment groups with titanium bases (zirconia [Z], lithium disilicate [L], ceramic-reinforced polymer [B] and [BC]) and a custom titanium abutment control group (T) were restored with monolithic zirconia crowns except BC, which was crowned with layered composite. Ceramic abutments were cemented on Ti bases with a self-curing resin cement. Polymer abutments were cemented on Ti bases with an adhesive resin cement. All crowns for T, Z, and L were cemented with another self-adhesive resin cement, while the B and BC groups were cemented with the same adhesive resin cement for the polymer. Fatigue testing was performed by a chewing simulator (CS-4.2, SD, 50 N, 240,000 cycles) followed by fracture strength testing (0.5 mm/min, 5,000 N). Failure type analysis was made by a stereomicroscope. Statistical analyses were made (SPSS 25.0, analysis of variance [ANOVA], Tukey honestly significant difference [HSD], 95% CI). Complementary finite element analyses (FEAs) were performed (Algor Fempro). Results: Mean ± SD fracture strengths for T, Z, L, B, and BC were 1,522.67 ± 190.77, 1,207.76 ± 89.03, 818.81 ± 109.96, 1,126.23 ± 142.23, and 899.08 ± 60.36, respectively (P < .05). Abutment screw flexure and/or cracks or crown material fractures for T, Z, L, and B occurred, while no implant and/or abutment fractures were observed for BC except for crown fracture and Ti base flexure. FEA exhibited similar stress concentrations. Conclusion: Monolithic zirconia crowns on titanium abutments and hybrid zirconia abutments exhibited the highest fracture strengths. Lithium disilicate and BioHPP abutments had the lowest fracture strength, while no fractures were observed on the implant, abutment, or screw. [ABSTRACT FROM AUTHOR]

This study evaluated the pull-off force between titanium abutments and zirconia crowns that were bonded using four different cements and two abutment heights (AHs). In total, 24 titanium abutments (3-mm AH: n = 12; 5-mm AH: n = 12; taper: 7.5 degrees) and 24 zirconia crowns were designed, manufactured, cemented with one of four dental cements (one temporary, two semi-permanent, one permanent), stored in water for 24 hours, and thermocycled (37,500 cycles, equal to ~4 years in vivo). The pull-off force needed to separate the abutment and crown in each combination was determined eight times per combination of cement type and abutment height. Statistical analysis was conducted at a significance level of P < .05. The permanent self-adhesive composite cement showed a high pull-off force with a risk for crown fracture (mean: 381 N for 3-mm AH; 617 N for 5-mm AH). In contrast, the temporary zinc-oxide cement showed frequent premature decementation after thermocycling (mean: 14 N with 3-mm AH; 28 N with 5-mm AH). Both semi-permanent methacrylate-based cements ranked between the other cements (mean: 31 N/37 N for 3-mm AH; 120 N/72 N for 5-mm AH). Statistically significant differences were found between all cements (ANOVA P < .001). The abutment heights differed significantly for all cements (P < .005) except for the temporary zinc-oxide cement. Methacrylate-based cements were the most reliable cements for semi-permanent mounting of zirconia crowns on titanium abutments. They provide sufficient retention to avoid unintended loosening and are weak enough to remove the crown without causing damage. [ABSTRACT FROM AUTHOR]

Purpose: To compare osteocalcin and crestal bone loss in implants placed under an immediate loading (IL) compared to a delayed loading (DL) protocol.Materials and Methods: This preliminary, split-mouth, randomized controlled trial included 14 participants who required replacement of both mandibular first molars opposing a completely dentate maxillary arch. Two implants were placed in each participant. According to the split-mouth randomization method, a temporary crown was used for the IL protocol and a healing abutment was used for the DL protocol in each participant. Definitive crowns were cemented 3 months after implant placement. Osteocalcin levels were determined using ELISA, and crestal bone loss was evaluated using radiographs at 2 weeks, 3 months, and 12 months after implant placement.Results: The mean osteocalcin level was significantly higher with IL than DL at each point (P < .001), with 95% CI of -262.89 to -439.10 (2 weeks); -238.02 to -375.98 (3 months); and -83.24 to -211.61 (12 months). Higher crestal bone loss was observed in IL when compared to DL implants at 2 weeks (P = .458, 95% CI: -0.10 to 0.21). Less crestal bone loss was observed with IL than DL at 3 months (P = .935) and 12 months (P = .42).Conclusion: Osteocalcin levels increased in both IL and DL implants, but higher levels were observed with IL. Higher crestal bone loss was observed with IL during the initial stages of treatment only. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the use of a new resin metal opaquer on the surface of titanium abutments, in combination with two luting agents, and its effect on the retentive strength of implant-supported zirconia copings. Materials and Methods: Sixty customized titanium abutments were designed and fabricated with virtual design software and a milling machine. Thirty abutment specimens were coated with metal opaquers, and the others were not coated. Then, the titanium abutments were fitted into the implant analogs, and the abutment-implant analog complexes were embedded in acrylic resin blocks. Sixty CAD/CAM-fabricated zirconia copings were seated on the abutments and secured with glassionomer cement or self-adhesive resin cement. The specimens were stored in 100% humidity for 1 hour and artificial saliva for 23 hours at 37°C before thermocycling for 5,000 cycles of 5°C to 55°C with a 30-second dwell time. The retentive strength was measured using a pull-out test with a universal testing machine. The dislodgment forces were statistically analyzed via two-way analysis of variance (ANOVA). The failure modes were evaluated and categorized by examining the fracture surface. Results: The metal opaquer material had a significant negative effect on retention of zirconia copings. The nonopaquer titanium abutments showed significantly (P < .05) higher retentive strength than the metal opaquer abutments. Comparing the cements, the retentive strength values of self-adhesive resin cement were significantly higher than those of glass-ionomer cement. The metal opaquer groups exhibited mostly mixed-type failures, a combination of adhesive failures and cohesive failures, whereas the nonopaquer groups showed mostly adhesive-type failures. Conclusion: The titanium abutments coated with the new metal opaquer material resulted in a reduction of retentive strength. Self-adhesive resin cements exhibited significantly higher retention than glass-ionomer cements. [ABSTRACT FROM AUTHOR]

Purpose: To determine the effect of 0.7- and 2.4-mm transmucosal abutment height titanium bases on the crestal bone stability and peri-implant soft tissue condition of bone-level implants with platform switching in patients with vertically thick soft tissues. Materials and Methods: Sixty bone-level platform-switched implants were placed in the molar and premolar regions of both arches in 60 patients. All epicrestally inserted nonsubmerged implants had a 4.1-mm diameter and, after osteointegration, were randomly allocated into two groups: (1) the short group, with a titanium base of 0.7-mm transmucosal abutment height, and (2) the high group with a 2.4-mm height. Monolithic zirconia restorations were fabricated for all implants. Parallel intraoral radiographs were obtained after the delivery of restorations (T1) and after 1 year (T2). Crestal bone levels and peri-implant soft tissue conditions were calculated for each implant. The significance level was set at α = .05. Results: After 1 year, 55 patients were evaluated, with a mean bone loss of 0.6 ± 0.51 mm (median: 0.71, range: 0 to 2.09 mm) in the short group (23 patients) and 0.45 ± 0.59 mm (median: 0.65, range: 0 to 2.12 mm) in the high group (22 patients), showing no significant difference between groups (P = .168). A significant increase in marginal bone height was noted between the T1 and T2 time points in the short and high (P = .029 and .001, respectively) groups. The peri-implant soft tissue health parameters did not show statistically significant differences. Conclusion: Crestal bone stability after 1 year of follow-up around epicrestally placed platform-switched implants is not influenced by transmucosal abutment height, if the vertical soft tissue thickness is ≥ 3 mm. [ABSTRACT FROM AUTHOR]

The present randomized controlled study was undertaken to evaluate and compare peri-implant hard and soft tissue changes between implants restored with multiple disconnections and reconnections of the abutment (control group) vs implants restored with a definitive abutment (test group). Twenty edentulous sites from 13 systemically healthy participants were selected for the study. The recorded clinical parameters were bleeding on probing (BOP) and peri-implant pocket depth (PIPD). The measured radiographic parameter was peri-implant marginal bone loss (PMBL). Two parameters were measured both clinically and by CBCT: distance from the cementoenamel junction to the alveolar crest and alveolar ridge width. At the time of surgery, sites were randomly assigned to either the control or test group. At 6 months, (1) BOP was absent in both groups, (2) PIPD increased in both groups and was significantly greater in the control group, and (3) the mean PMBL was significantly higher in the control group than the test group. Thus, it can be concluded that the use of implants with a definitive abutment could be more beneficial in achieving better maintenance of marginal peri-implant tissue health. [ABSTRACT FROM AUTHOR]

Purpose: To review the factors that affect the ability to deliver a CAD/CAM implant-supported provisional restoration designed from a virtually planned implant position prior to surgical placement with static computer-assisted implant surgery (sCAIS). Materials and Methods: Data were collected on patients treated with single-tooth implant treatment in which CBCT was combined with intraoral scans and imported into a virtual implant planning software. A synchronization tool established the connection between the planning software and the CAD software, where a digital diagnostic tooth arrangement was performed to create the ideal tooth dimensions and mucosal architecture. The virtual implant planning was finalized, and the implant position was transferred to the CAD software, where a restoration was designed and fabricated. The sCAIS was performed, and the prefabricated custom restorations were delivered on the day of the surgery or following healing if delayed loading or submerged healing was required. Descriptive statistics and statistical comparison with two-proportion z test were performed. Results: A total of 23 patients with 28 single-implant sites met the inclusion criteria and were included in the study. Nineteen customized healing abutments and 10 provisional crowns were designed and fabricated for a total of 29 restorations. Of the restorations, 23 were successfully delivered on the day of the surgical intervention. No statistical significance was found among the different variables compared. Conclusion: Custom prefabricated CAD/ CAM restorations based on a virtually planned implant position can be successfully designed, fabricated, and delivered when used in combination with sCAIS. [ABSTRACT FROM AUTHOR]

Purpose: Implant surgical guides are often fabricated using CBCT technology. In this study, an alternative technique is proposed. The aim of this in vitro study was to compare the accuracy of the guide sleeve corrections of a geometric approach to guided surgery to the accuracy of in vitro studies of stereolithographic guides. Materials and Methods: Four arch forms were milled from acrylic blocks each with 12 root form sites. Root form inserts were made. Holes were milled in the inserts at arbitrary angles. Guide posts were placed in these sites. Guide sleeves were placed on the posts and connected with light-cured resin to form verification jigs. The goal was to correct the angles of the guide sleeves to a vertical position 90 degrees from the base of the arch forms. The initial angles from the vertical and horizontal positions of the center of each guide sleeve were determined radiographically and geometrically. Horizontal and angle corrections were made using two-piece guide posts. Guide sleeves placed over the corrected guide posts were connected with lightcured resin, forming new verification jigs. The accuracy of the angle correction and the coronal horizontal and apical horizontal deviations of the 3-mm guide sleeves were determined. The experimental sites were divided into two groups to determine if the size of the initial angles of the guide sleeves had any effect on the accuracy of the corrections. Results: The initial angles of the guide sleeves before corrections revealed the mean difference between the two methods of measurements in groups 1 and 2 as 0.36 degrees (P = .14) and 0.69 degrees (P = .07), respectively. A comparison of the angle error measurements from 90 degrees after corrections between the two groups in the mesiodistal and buccolingual planes was not significant. The coronal and apical horizontal deviations after corrections revealed a significant difference between the two groups at the coronal level (P = .005) but not at the apical level (P = .14). In comparison of the methods of the two measurements of the angle error from vertical after corrections, the mean difference was 1.23 degrees (P = .01) and 0.69 degrees (P = .02). Conclusion: The in vitro accuracy of the guide sleeve corrections made with the geometric approach for implant guidance was compared to the results of the meta-analyses of in vitro studies of implant placement with stereolithographic guides. The mean errors were smaller and within the recommendations of the EAO Consensus Conference of 2012. [ABSTRACT FROM AUTHOR]

Purpose: Investigate the effects of three different complete-arch digital implant scanning techniques used with a combined healing abutment–scan body (CHA-SB) system on the accuracy (trueness and precision) and scan time. Materials and Methods: A poly(methyl methacrylate) master model simulating an edentulous maxilla was fabricated with four parallelly inserted dental implants. A CHA-SB system was attached to each implant. The model surface was scanned using a structured blue light industrial extraoral scanner to achieve a reference model standard tessellation language file (MRM-STL). Three different scanning techniques—(1) conventional technique with unmodified master model, (2) scan body splinting technique using orthodontic elastic ligatures and plastic splint materials, and (3) land-marking technique using pyramid-shaped glass-ceramic markers—were performed. Fourteen consecutive digital scans were made by using an intraoral scanner (IOS) for each technique, converted to an STL file, and superimposed on the MRM-STL. Trueness and precision were calculated for each technique. The scan time was also recorded. The data were analyzed with one-way analysis of variance (ANOVA) and Tukey honest significant difference (HSD) tests (α = .05). Results: Effects of different scanning techniques on the trueness (distance and angular deviations; P < .001) and scan time (P = .002) were statistically significant. For precision, different scanning techniques had only a significant effect on the distance deviation (P < .001). Conclusion: Regarding trueness and precision, none of the scanning techniques was superior to others. The scan body splinting technique led to significantly less scan time. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aim: The aim of the study was to evaluate the 5 years clinical outcomes associated with implant‐level connection (IL) versus abutment‐level connection (AL) for implants with an internal conical connection (ICC) supporting a screw‐retained fixed partial denture. Materials and Methods: Fifty patients with 119 implants were randomly allocated to either the AL or IL group. Radiographic (Marginal bone loss) and clinical outcomes (Bleeding on Probing, probing pocket depth, plaque accumulation, incidence of peri‐implantitis and peri‐implant mucositis as well as prosthetic complications) were collected and compared at 1, 2, 3, and 5 years. A linear mixed model was used to evaluate the differences between groups. Results: Five years after treatment, the MBL change was not significantly different between the groups at any point. The MBL was 0.23 ± 0.64 mm (AL) and 0.23 ± 0.29 mm (IL). The bleeding on Probing was 44% (AL) and 45% (IL) (p =.89). The mean probing depth was 2.91 ± 1.01 mm (AL) and 3.51 ± 0.67 mm (IL). This difference between the groups was statistically significant but clinical insignificant. Presence of plaque was slightly higher (p =.06) in the IL group (34.4%) compared with the AL group (26.3%). The overall technical, biological, and prosthetic complication rates were similar between groups. None of the implants developed peri‐implantitis during the entire follow‐up period. Conclusion: The results of this clinical trial indicated that all clinical and radiographical parameters were clinically comparable between the study groups. [ABSTRACT FROM AUTHOR]