In Vitro Comparison of Internal and Marginal Adaptation between Printed and Milled Onlays.

STATEMENT OF PROBLEM: Nowadays, milling is still the gold standard for fabricating indirect restorations, but to overcome its disadvantages, there are alternatives, such as 3D printing. PURPOSE: This study aimed to compare the gaps between the prepared tooth and milled and printed onlays fabricated with the same CAD design. It also aimed to determine the gap reproducibility across onlays fabricated by 3D printing and milling. METHODS: A resin tooth was prepared for an onlay. After scanning the preparation, an onlay was designed with proprietary dental software. Next, 22 onlays were milled in a graphene-reinforced PMMA disc (Group 1), and 22 onlays were 3D-printed with a hybrid composite material (Group 2). After that, all fabricated restorations were scanned and superimposed on the scanned prepared resin tooth. Subsequently, a specific software was used to measure the margin, central, and intaglio-located gap between the milled or printed restoration and the preparation. Finally, measurements were compared with a multifactor analysis of variance. RESULTS: The results demonstrated that printed onlays (Group 2) adapted better to the prepared tooth than the milled ones (Group 1) (p < 0.05). The comparison of standard deviations showed the better gap reproducibility of printed onlays (p < 0.05). CONCLUSION: This study concluded that the printed onlays adapted significantly better to the prepared tooth than the milled onlays. Printed onlays also showed significantly better gap reproducibility.

Reverse impression technique: A fully digital protocol for the fabrication of the definitive fixed prosthesis for completely edentulous patients.

In complete arch implant rehabilitation, one of the greatest difficulties still encountered in the digital workflow is the deviation of the implant position during intraoral scanner (IOS) data acquisition. As a result, the passivity of a definitive prosthesis fabricated using IOS data might be compromised. Thus, an implant position verification method is essential, either digitally or conventionally executed. A fully digital protocol for the fabrication of the definitive fixed prosthesis for completely edentulous patients, without the interference of any conventional step within the digital process, is presented. For the verification of the captured position of the scan-bodies, novel scan analogs were connected to the interim prosthesis extraorally and scanned. The virtual superimposition of the interim prosthesis intraorally with the same prosthesis extraorally served as a verification device for the position of the implants.

A Systematic Study of Restorative Crown-Materials Combinations for Dental Implants: Characterization of Mechanical Properties under Dynamic Loads.

This study aimed to find the optimum mechanical characteristics of the restorative materials for the manufacture of implant crowns subjected to impact loading when different combinations of materials are used for the inner and outer crown. Several combinations of external-internal crown restorative materials were analyzed. The dynamic stresses at eight different zones of a dental implant subjected to an impact load and the influence of several mechanical properties, such as the Young's modulus, Poisson's ratio, density, and initial velocity, were analyzed and compared. A detailed 3D model was created, including the crown, the retention screw, the implant, and a mandible section. The model was then built by importing the 3D geometries from CAD software. The whole 3D model was carefully created in order to guarantee a finite element mesh that produced results adjusted to physical reality. Then, we conducted a numerical simulation using the finite element method (FEM). The results of the FEM analysis allowed for evaluating the effect that different combinations of restorative materials and mechanical properties had on the stress distribution in various regions of the implant. The choice of restorative material is a factor to be considered in order to preserve the integrity of osseointegration. Restorative materials transfer more or less stress to the dental implant and surrounding bone, depending on their stiffness. Therefore, an inadequate Young's modulus of the rehabilitation material can affect the survival of the implant over time. Eight interactive graphics were provided on a web-based surface platform to help clinical dentists, researchers, and manufacturers to select the best restorative materials combination for the crown.

Covariates Relating to Implant Failure and Marginal Bone Loss of a Novel Triangular Neck-Implant Placed by Post-Graduate Students: A 1-Year Prospective Cohort Study.

(1) Background: Most of the clinical literature dealing with dental implants has been issued by experienced teams working either in university settings or in private practice. The purpose of this study was to identify contributing covariates to implant failure and marginal bone loss (MBL) at the 1-year follow-up of a novel triangular-neck implant design when placed by inexperienced post-graduate students. (2) Methods: A prospective cohort study was conducted on study participants eligible for implant placement at the UIC (International University of Catalonia), Barcelona, Spain. Implant failure rate and contributors to implant failure and MBL were investigated among 24 implant and patient variables. (3) Results: One hundred and twenty implants (V3, MIS) were placed and rehabilitated by the students. The mean insertion torque was 37.1 Ncm. Survival and success rates were 97.5% and 96.7%, respectively. Implants placed in patients with smoking habits displayed a tendency of higher failure risk (OR = 5.31, p = 0.17) when compared to non-smokers. The mean (SD) MBL was 0.51 (0.44) mm. Gender significantly affected the MBL (p = 0.020). Bleeding on probing (BoP) on the buccal sites proved to be a good predictor of proximal MBL (p = 0.030). (4) Conclusions: The survival and success rates of the V3 triangular-neck implant placed by inexperienced post-graduate students at the 1-year follow-up were high and similar to the ones published in the literature by experienced teams on other implants.

Bone Stress Evaluation with and without Cortical Bone Using Several Dental Restorative Materials Subjected to Impact Load: A Fully 3D Transient Finite-Element Study.

Statement of problem. Previous peri-implantitis, peri-implant bone regeneration, or immediate implant placement postextraction may be responsible for the absence of cortical bone. Single crown materials are then relevant when dynamic forces are transferred into bone tissue and, therefore, the presence (or absence) of cortical bone can affect the long-term survival of the implant. Purpose: the purpose of this study is to assess the biomechanical response of dental rehabilitation when selecting different crown materials in models with and without cortical bone. Methods: several crown materials were considered for modeling six types of crown rehabilitation: full metal (MET), metal-ceramic (MCER), metal-composite (MCOM), peek-composite (PKCOM), carbon fiber-composite (FCOM), and carbon fiber-ceramic (FCCER). An impact-load dynamic finite-element analysis was carried out on all the 3D models of crowns mentioned above to assess their mechanical behavior against dynamic excitation. Implant-crown rehabilitation models with and without cortical bone were analyzed to compare how the load-impact actions affect both type of models. Results: numerical simulation results showed important differences in bone tissue stresses. The results show that flexible restorative materials reduce the stress on the bone and would be especially recommendable in the absence of cortical bone. Conclusions: this study demonstrated that more stress is transferred to the bone when stiffer materials (metal and/or ceramic) are used in implant supported rehabilitations; conversely, more flexible materials transfer less stress to the implant connection. Also, in implant-supported rehabilitations, more stress is transferred to the bone by dynamic forces when cortical bone is absent.

A 3D Finite Element Analysis Model of Single Implant-Supported Prosthesis under Dynamic Impact Loading for Evaluation of Stress in the Crown, Abutment and Cortical Bone Using Different Rehabilitation Materials.

In the literature, many researchers investigated static loading effects on an implant. However, dynamic loading under impact loading has not been investigated formally using numerical methods. This study aims to evaluate, with 3D finite element analysis (3D FEA), the stress transferred (maximum peak and variation in time) from a dynamic impact force applied to a single implant-supported prosthesis made from different materials. A 3D implant-supported prosthesis model was created on a digital model of a mandible section using CAD and reverse engineering. By setting different mechanical properties, six implant-supported prostheses made from different materials were simulated: metal (MET), metal-ceramic (MCER), metal-composite (MCOM), carbon fiber-composite (FCOM), PEEK-composite (PKCOM), and carbon fiber-ceramic (FCCER). Three-dimensional FEA was conducted to simulate the collision of 8.62 g implant-supported prosthesis models with a rigid plate at a speed of 1 m/s after a displacement of 0.01 mm. The stress peak transferred to the crown, titanium abutment, and cortical bone, and the stress variation in time, were assessed.

Comparison between experimental digital image processing and numerical methods for stress analysis in dental implants with different restorative materials.

The aim of this study is to evaluate the stresses transferred to peri-implant areas from single implants restored with different restorative materials and subjected to a static vertical load with low eccentricity. A total of 12 crowns were made with four types of materials: carbon fiber-composite, metal-ceramic, metal-composite, and full-metal, all of them cemented over a titanium abutment. Three different ways of approaching the problem have been used independently to verify the robustness of the conclusions. The experimental results of stress distribution around the implant were obtained by two image processing techniques: Digital Photoelasticity and Digital Image Correlation (DIC). The tests have been modelled by 3D Finite Element Method (FEM). The FEM models have also been used to study the sensitivity of the results to slight changes in geometry or loads, so that the robustness of the experimental techniques can be analyzed. In addition, the realistic bone morphology of the mandible has also been modelled by FEM, including the cortical and trabecular bone property distinctions.

Protocol for the clinical assessment of passive fit for multiple implant-supported prostheses: A dental technique.

With monolithic materials and the new technologies for framework production, assessment of passive fit before fabrication of the definitive prosthesis or its framework is essential to avoid prosthesis remakes. This article describes an updated clinical protocol to assess passive fit during the prosthesis fabrication process through the systematic use of tactile feel while tightening the retaining screws, the visual or radiographic evaluation when performing the 1-screw or Sheffield fit test, and the torque/time graph obtained during the placement of the implant- or abutment-retaining screws with a torque-controlled surgical motor.

Fracture Resistance of Two Different Composite Resin CAD/CAM Crowns Bonded to Titanium Abutments.

PURPOSE: To determine the influence of thermal and mechanical cycling on fracture load and fracture pattern of resin nanoceramic crowns and polymer-infiltrated ceramic-network (PICN) crowns, both fabricated with CAD/CAM technology. MATERIALS AND METHODS: A total of 90 premolar crowns bonded to titanium abutments were divided into three groups of 30 crowns each: 30 resin nanoceramic crowns (LU); 30 PICN crowns (VE); and 30 metal-ceramic crowns (MC). The 30 specimens of each group were further divided into three subgroups of 10 each that underwent (1) no treatment, (2) thermocycling (2,000 cycles, 5°C to 55°C), and (3) thermocycling with subsequent mechanical cycling (120,000 cycles, 80 N, 2 Hz). The specimens were loaded to failure, and two-way ANOVA and chi-square test were used to determine differences in fracture resistance and pattern. RESULTS: Mechanical and thermal cycling significantly influenced the critical load to failure of the three materials; however, no significant differences were observed between the thermocycled materials and the materials that were thermocycled with subsequent mechanical cycling. The MC specimens experienced significantly higher fracture loads than those of the LU and VE specimens, which showed no differences from each other in fracture resistance. The fracture patterns showed chipping in MC crowns and partial or complete fracture in LU and VE crowns. The fracture pattern depended on the material and was unrelated to the type of treatment it underwent. CONCLUSION: All crowns showed adequate resistance to normal masticatory forces in the premolar area. The cyclic fatigue load negatively influenced all three materials.

Factors Affecting Implant Failure and Marginal Bone Loss of Implants Placed by Post-Graduate Students: A 1-Year Prospective Cohort Study.

STATEMENT OF THE PROBLEM: Most of the clinical documentation of implant success and survival published in the literature have been issued by either experienced teams from university settings involving strict patient selection criteria or from seasoned private practitioners. By contrast, studies focusing on implants placed and rehabilitated by inexperienced post-graduate students are scarce. PURPOSE: To record failure rates and identify the contributing factors to implant failure and marginal bone loss (MBL) of implants placed and rehabilitated by inexperienced post-graduate students at the one-year follow-up. MATERIAL AND METHODS: A prospective cohort study was conducted on study participants scheduled for implant therapy at the International University of Catalonia. An experienced mentor determined the treatment plan in accordance with the need of each participant who signed an informed consent. All surgeries and prosthetic rehabilitation were performed by the post-graduate students. Implant failure rate, contributors to implant failure, and MBL were investigated among 24 variables related to patient health, local site, and implant and prosthetic characteristics. The risk of implant failure was analyzed with a simple binary logistic regression model with generalized equation equations (GEE) models, obtaining unadjusted odds ratios (OR). The relationship between MBL and the other independent variables was studied by simple linear regression estimated with GEE models and the Wald chi2 test. RESULTS: One hundred and thirty dental implants have been placed and rehabilitated by post-graduate students. Five implants failed before loading and none after restoration delivery; survival and success rates were 96.15% and 94.62%, respectively. None of the investigated variables significantly affected the implant survival rate. At the one-year follow-up, the mean (SD) MBL was 0.53 (0.39) mm. The following independent variables significantly affected the MBL: Diabetes, implant depth placement. The width of keratinized tissue (KT) and probing depth (PD) above 3 mm were found to be good indicators of MBL, with each additional mm of probing depth resulting in 0.11 mm more MBL. CONCLUSION: The survival and success rates of dental implants placed and rehabilitated by inexperienced post-graduate students at the one-year follow-up were high. No contributing factor was identified regarding implant failure. However, several factors significantly affected MBL: Diabetes, implant depth placement, PD, and width of KT. CLINICAL IMPLICATIONS: Survival and success rates of dental implants placed and rehabilitated by inexperienced post-graduate students were high at the one-year follow-up, similar to experienced practitioners. No contributing factors were identified regarding implant failure; however, several factors significantly affected MBL: Diabetes, implant depth placement, PD, and KM.

Snoring intensity assessment with three different smartphones using the SnoreLab application in one participant.

STUDY OBJECTIVES: To compare the assessment of snoring using the SnoreLab application (app) using three different smartphones by one participant to validate SnoreLab as a method for collecting data for studies on the effectiveness of snoring treatment. METHODS: A person from the research group was monitored for 30 consecutive nights with the SnoreLab app using three different smartphones (Xiaomi MI8Pro, Samsung Galaxy Alpha, and BQ Aquaris V). The SnoreLab app instructions were strictly followed, and data were collected from the app. RESULTS: No significant differences were found in the measurements from the three smartphones in the time in bed, all snoring time, snoring percentage, and quiet time. BQ and Samsung smartphones determined significantly more light snoring time than did the Xiaomi smartphone. The Samsung smartphone assessed significantly less loud snoring time than did the Xiaomi smartphone and measured the shortest epic snoring time. The lowest Snore Score was calculated with the Samsung smartphone, the highest with the Xiaomi smartphone. Pearson's correlation coefficients demonstrated a relatively strong relationship between the Snore Score measured with the three smartphones. CONCLUSIONS: Even though there was a relatively strong relationship between the Snore Score measured with the three smartphones by one participant, the observed differences make it difficult to use this index as a method of collecting data for studies on snoring treatment effectiveness when patients use different smartphones; however, the SnoreLab app may be handy to quantify treatment effectiveness for a specific patient, provided the patient always uses the same smartphone.