Optical impressions assessment for overlay restorations with rubber dam: A clinical trial.

OBJECTIVE: The possibility of making impressions of teeth prepared with a rubber dam in place has been proposed; however, this requires trimming and rescanning the mesh, which has been described as a cause of accuracy loss. This study aims to clinically determine whether overlay restorations obtained from a scan with a rubber dam in place have equivalent marginal fit, contact points, and occlusal fit to the same type of restorations obtained from a scan without a rubber dam. MATERIAL AND METHODS: Thirty patients who underwent overlay restoration of a molar with at least one neighbouring tooth were selected. After tooth preparation, two scans were performed: one without a rubber dam and the other with a rubber dam. Restorations were randomly created from one scan or another. The marginal fit, interproximal contact points, and occlusal fit were evaluated clinically. Two meshes, with and without rubber dams, were also compared. RESULTS: No significant differences were observed in the clinical evaluation of the overlays made of the two meshes. The trueness of the mesh from the impression made with a rubber dam with respect to the mesh without a rubber dam was about 40 µm in the critical areas of the preparation (margins, intaglio, and interproximal contact points). CONCLUSIONS: The results of this study show that under the conditions performed and with the equipment used, there are no significant clinical differences between overlay restorations made from a scan with a rubber dam and those made from a scan without a rubber dam. CLINICAL SIGNIFICANCE: Scanning with a rubber dam in place may be a valid option for certain types of restorations under certain clinical conditions.

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.

CAD-CAM and analog occlusal splints comparison based on the amount of occlusal adjustments. 3D analysis of the volumetric changes: A pilot study.

OBJECTIVE: To evaluate the volumetric changes on occlusal surface of computer-aided design and computer-aided manufacturing (CAD-CAM) occlusal devices fabricated following a fully digital workflow after occlusal adjustment, compared to those fabricated with an analog workflow. MATERIALS AND METHODS: Eight participants were included in this clinical pilot study, receiving two different occlusal devices fabricated with two different workflows, fully analog and fully digital. Every occlusal device was scanned before and after the occlusal adjustments to compare the volumetric changes using a reverse engineering software program. Moreover, three independent evaluators assessed a semi-quantitative and qualitative comparison using visual analog scale and dichotomous evaluation. The Shapiro-Wilk test was performed to validate normal distribution assumption, and a dependent t-Student test for paired variables was used to determine statistically significant differences (p-value < 0.05). RESULTS: The root mean square value was extracted from the 3-Dimensional (3D) analysis of the occlusal devices. The average values of the root mean square were higher for the analogic technique (0.23 ± 0.10 mm) than the digital technique (0.14 ± 0.07 mm) but the differences were not statistically significant (paired t-Student test; p = 0.106) between the two fabrication techniques. The semiquantitative visual analog scale values between the impression for the digital (5.08 ± 2.4 cm) and analog (3.80 ± 3.3 cm) technique were significant (p < 0.001), and statistically significant differences values were assessed for evaluator 3 compared to the other evaluators (p < 0.05). However, the three evaluators agreed on the qualitative dichotomous evaluation in 62% of the cases, and at least two evaluators agreed in 100% of the evaluations. CONCLUSIONS: Occlusal devices fabricated following a fully digital workflow resulted in fewer occlusal adjustments, as they could be a valid alternative to those fabricated following an analog workflow. CLINICAL SIGNIFICANCE: Fabricated occlusal devices following a fully digital workflow could have some advantages over analog workflow such reduce occlusal adjustments at delivery appointment, which can result in reduced chair time and therefore increased comfort for the patient and clinician.

Comparison accuracy of digital and analog method using milled occlusal splints.

OBJECTIVE: This clinical trial aims to compare the accuracy of interocclusal registration in centric relation taken with polyvinyl siloxane and intraoral scanner (IOS) with the fabrication of occlusal devices. METHODS: Thirty-one participants were included in the trial registered at ClinicalTrials.gov (NCT05317182) receiving two different occlusal devices from two different workflows. One workflow was performed using polyvinyl siloxane impression material and the other with IOS. Every splint was scanned before and after the occlusal adjustments to compare the volumetric changes using the Root Mean Square deviation (RMS). Furthermore, three evaluators assessed the 3D comparison using color maps in a Visual Analog Scale (VAS). RESULTS: The average values of RMS were higher for the analog approach (0.01 ± 0.067) than the digital approach (0.065 ± 0.035). However, the differences were not statistically significant (p < 0.063) between the two impression techniques. For the semiquantitative analysis performed by blinded evaluators, differences in VAS values between the impression for the digital (2.08 ± 2.4) and analog (3.80 ± 3.3) technique were statistically significant. The three evaluators agreed in more than 90% of the qualitative dichotomous evaluation. CONCLUSION: Digital impressions did not show inferior accuracy compared to conventional impressions when assessed using quantitative measurements. CLINICAL SIGNIFICANCE: This clinical trial provided evidence on registering interocclusal relationship at increased vertical dimension with fully digital workflow for complete arch prosthesis.

A fully digital protocol to provide a fixed interim complete denture for immediate loading for a completely edentulous patient: A dental technique.

Complete arch immediate-loading implant-supported prostheses can represent a major challenge for the patient and the dental team. Obtaining stable references and an accurate occlusal record after implant placement to provide an interim prosthesis is a difficult task and can deviate from the initial treatment plan. The described technique presents a fully digital protocol to provide an immediate complete arch implant-supported fixed interim prosthesis for edentulous patients by making postoperative cone beam computed tomography and intraoral digital scans that correlate with the previous plan.

Perceptions of plagiarism among PhDs across the sciences, engineering, humanities, and arts: Results from a national survey in Brazil.

Plagiarism allegations are not rare in the history of science, and credit for prior work was and continues to be a source of disputes, involving notions of priority of discovery and of plagiarism. However, consensus over what constitutes plagiarism among scientists from different fields cannot be taken for granted. We conducted a national survey exploring perceptions of plagiarism among PhD holders registered in the database of the Brazilian National Council for Scientific and Technological Development. This survey was sent to 143,405 PhD holders across the fields, in the sciences, engineering, humanities, and arts, with a response rate of about 20%. The results suggest that core principles about plagiarism are shared among this multidisciplinary community, corroborating Robert K. Merton's observations that concerns over plagiarism and priority disputes are not field specific. This study offers insight into the way plagiarism is perceived in this community and sheds light on the problem for international collaborative research networks. The data focus on a particular research system in Latin America, but, given the cultural similarities that bind most Latin American nations, these results may be relevant to other PhD populations in the region and should provide an opportunity for comparison with studies from other emerging, non-Anglophone regions.

Digital workflow for designing an interim implant-supported restoration with an optimal emergence profile in an open-source software program.

The esthetics and emergence profile design of implant-supported restorations in the anterior zone can be challenging. This dental technique describes a digital approach to designing an optimal emergence profile from the implant head to the definitive prosthetic volume with facial cutback for an esthetic implant-supported interim crown. A printed interim implant-supported restoration with an adequate emergence profile and a facial cutback for composite resin layering is obtained.

Fabrication of a CAD-CAM combination matrix for trial restorations: A dental technique.

The trial restoration increases outcome predictability in restorative treatments, enhances communication among specialists and patients, and guides tooth preparations. It should reproduce the planned design precisely because many decisions will be made based on the transferred design. Traditionally, a diagnostic waxing design is transferred to the mouth with a flexible silicone matrix. However, a rigid matrix would ensure an accurate transfer of the planned design by avoiding the deformation of the silicone index. A step-by-step technique for fabricating a computer-aided design and computer-aided manufactured (CAD-CAM) rigid matrix relined with polyvinyl siloxane material to fabricate a trial restoration is presented. The technique ensures accurate detail reproduction and dimensional stability, avoiding deformation and ensuring a predictable transfer of the planned design.

ECT: A decision to decrease risks during COVID-19 pandemic / TEC: una decisión para disminuir riesgos durante la pandemia COVID-19

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The digital alveolar cast: A revised approach to an old concept.

An alveolar cast is recommended for the fabrication of specific fixed dental prostheses. The analog workflow for such casts is labor-intensive, time-consuming, and highly skill dependent. Advancements in digital technologies are bringing new, efficient, and streamlined protocols for dental practice. This article presents a digital workflow for the fabrication of an alveolar cast by using computer-aided design and computer-aided manufacturing (CAD-CAM)technologies.

Magnetic extrusion technique for restoring severely compromised teeth: A case report.

An orthodontic magnetic extrusion technique is described for the management of an extensively damaged maxillary premolar. A cylindrical neodymium-iron-boron (Nd2Fe14B) magnet was attached to the remaining tooth structure, and a second magnet was placed on a resin-bonded partial denture. A 4.5-mm extrusion was obtained after 3 adjustments, and the tooth was prepared with a 3-mm buccal and 2-mm lingual ferrule by following a biologically oriented preparation technique and restored with a monolithic zirconia crown. Eighteen months after completing the treatment, no evidence of soft tissue dehiscence, abnormal tooth mobility, endodontic failure, or root resorption was found.

Fabrication of a facially generated tooth reduction guide for minimally invasive preparations: A dental technique.

This article describes a 3D virtual diagnostic analysis for treatment planning an esthetically driven functional rehabilitation by using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. In this protocol, a digitally planned diagnostic waxing (exocad DentalCAD) was used to visualize the proposed tooth position and the presence of areas without sufficient material thickness for the prospective additive restorations. This approach uses an additively manufactured clear resin guide to selectively reduce surfaces of a tooth erupted beyond the proposed occlusal plane. By using a 3D-printed occlusal reduction guide, the digital diagnostic waxing is accurately represented, tooth reduction controlled, and adequate occlusal clearance for the required restorative material thickness provided with a minimally invasive approach.

Fit of complete-arch implant-supported prostheses produced from an intraoral scan by using an auxiliary device and from an elastomeric impression: A pilot clinical trial.

STATEMENT OF PROBLEM: The accuracy of impressions for implant-supported prostheses is essential to ensure a passive fit of the definitive prosthesis. Intraoral scanners (IOSs) have been developed as an alternative to complete-arch implant-supported restorations; however, whether they are sufficiently accurate when more than 3 nonaligned implants are involved is unclear. PURPOSE: The purpose of this pilot clinical study was to determine whether the fit of complete-arch zirconia implant-supported frameworks processed on a cast obtained with an IOS and adjusted with an auxiliary device is equivalent to a prosthesis obtained from an elastomeric impression. MATERIAL AND METHODS: Twelve consecutive participants who were ready for complete-arch restorations on already osseointegrated implants were enrolled. Two records were made, one open-tray with polyether and splinted impression copings and the second with an IOS. A verification gypsum device was used for the elastomeric impression, and a prefabricated auxiliary device was used to adjust the intraoral scans. Two zirconia frameworks with the same design were processed and evaluated intraorally by 2 independent calibrated observers. RESULTS: In 11 of the 12 participants, the digitally processed prosthesis was preferred over the conventionally processed prosthesis. The clinical fit of the prostheses obtained with the completely digital workflow was better than that of those obtained with the conventional workflow. CONCLUSIONS: The use of a prefabricated auxiliary device after intraoral scanning allowed delivery of complete-arch implant-supported monolithic zirconia prostheses with a fit better than those fabricated from conventional impressions.

Stone verification device for verifying the definitive cast of an implant-supported restoration: A dental technique.

To reduce the risk of implant and prosthetic complications, implant-supported prostheses should be passive. A verification device is used to verify the abutment analog position on the definitive cast, and hence its accuracy. This article describes the fabrication of a Type IV stone implant verification device for verifying the accuracy of the definitive cast.

European Society of Endodontology position statement: The restoration of root filled teeth.

This position statement on the restoration of root filled teeth represents the consensus of an expert committee, convened by the European Society of Endodontology (ESE). Current clinical and scientific evidence, as well as the expertise of the committee, have been used to develop this statement. The aim is to provide clinicians with evidence-based principles for decision-making on the choice of restoration following the completion of root canal treatment. By discussing the evidence in relation to key topics regarding post-endodontic restoration, a series of clinical recommendations are made. The scientific basis of the recommendations made in this paper can be found in a recently published review article (Bhuva et al. 2021, International Endodontic Journal, https://doi.org/10.1111/iej.13438). It is the intention of the committee to update this statement as further evidence emerges.

Digital scanning under rubber dam: An innovative method for making definitive impressions in fixed prosthodontics.

OBJECTIVE: To provide a comprehensive protocol for final impressions making under rubber dam isolation by using an intraoral scanner. CLINICAL CONSIDERATION: Impression making after tooth preparation with rubber dam isolation are impossible with conventional physical impressions, which are not with intraoral scanners. Digital technologies have disrupted dentistry in the last decades, bringing new, straightforward, and more time-efficient protocols for dental practice. CONCLUSIONS: Taking in consideration the beneficial properties of scanning under rubber dam this protocol can be highly recommended for everyday use for making definitive intraoral scans for tooth-supported restorations. CLINICAL SIGNIFICANCE: The described protocol offers the possibility to make a final impression in a stress-free environment, without blood or saliva, to obtain a better visualization and scanning of the finish line, and the potential of save time on definitive impression making.

Guided tooth autotransplantation in edentulous areas post-orthodontic treatment.

OBJECTIVE: Tooth autotransplantation with a complete root formation to replace one or more lost teeth is indicated as a cost-effective alternative to implants. The aim of this case report was to describe a successfully guided autotransplantation of a maxillary third molar with fully formed roots into a surgically created socket after orthodontic space opening. CLINICAL CONSIDERATIONS: A guided autotransplantation of the maxillary left third molar into the missing maxillary left first molar site was chosen. After virtually orientating donor tooth to confirm its optimum fit, it was deemed necessary to open 4 mm the mesiodistal space. Following the orthodontic movement, a 3-dimensional (3D)-guiding template and a milled surgical guide were manufactured to allow the donor tooth to be transplanted exactly in the planned position. The 2-year follow-up periapical radiograph showed a continuous periodontal space with no signs of apical periodontitis or root resorption. CONCLUSIONS: Virtual planning and 3D-printed tooth replica combined with guided surgery can simplify the autotransplantation technique for both the clinician and the patient, particularly when the socket has been completely created during surgery. CLINICAL SIGNIFICANCE: Virtual digital planning, which can accurately calculate the exact space to open orthodontically before an autotransplantation, could prove essential to enhancing the precision of 3D placement of the donor tooth in the recipient site.

Restoration's thickness and bonding tooth substrate are determining factors in minimally invasive adhesive dentistry.

Purpose To explore fracture strength and failure behaviour of minimally invasive CAD-CAM composite resin overlay restorations.Methods Eighty bi- and tri-layer cylindrical overlay model including the restoration bonded over bovine tooth dentin (Groups D) and enamel-dentin (Groups E) were assembled (diameter 9 mm). Restorations were milled from CAD-CAM composite resin blocks (Brilliant Crios, Coltène/Whaledent AG) in different thicknesses (0.5mm, 1mm, 1.5mm, 2mm) and equally distributed in four Groups D and four Groups E (n=10). All specimens were submitted to an Hertzian load-to-failure contact test with spherical indenter. Critical loads were recorded in Newton and data were analysed using Kruskal-Wallis test for multiple and Mann-Whitney test for 2-samples comparisons (p < 0.05). Fragments were examined using SEM. The stress distribution for specimens with restorations of 0.5 mm and 2 mm was also investigated with FEA.Results For all specimens, the mean static loads in Newton increased with an increase in restoration thickness. On contrary, restorations with the same thickness displayed higher resistance values when bonded over enamel than dentin, except for the 2-mm thick restorations. A damage competition was detected between cone/median cracks originating at the loading contact area of the restorations and radial cracks beginning at their inner surface, with the former prevailing in restorations bonded on enamel and the latter being dominant for restorations bonded on dentin.Conclusions For bonded ultra-thin resin composite restorations (0.5 mm to 1.5 mm) enamel as bonding substrate assures higher critical loads to fracture than dentin. This influence gradually decreases as restoration thickened.