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.

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.

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.

In vitro comparison of the accuracy of four intraoral scanners and three conventional impression methods for two neighboring implants.

PURPOSE: To determine whether the accuracy of two-implant model impressions taken with optical scanners was inferior to that of those taken with elastomeric materials. MATERIALS AND METHODS: Impressions of a resin reference model with two almost parallel implants were taken using three elastomeric impressions (closed tray technique, open tray nonsplinted technique and open tray splinted technique) and scanned with four optical scanners (CEREC Omnicam, 3M True Definition Scanner, 3Shape TRIOS3 and Carestream CS 3600). STL files of the different methods were superimposed and analyzed with control software (Geomagic Control X, 3D systems) to determine the mean deviation between scans. RESULTS: Compared to elastomeric impressions, optical impressions showed a significantly improved mean precision. TRIOS3 and CS3600 showed a significantly improved mean trueness compared to that of closed tray, CEREC Omnicam and TrueDefinition. All methods showed a certain degree of implant rotation over their axes, which was significantly higher in the closed tray and the open tray nonsplinted techniques. CONCLUSIONS: Optical impressions, taken under these in vitro conditions, showed improved accuracy compared with that of elastomeric impressions.

Immediately loaded interim complete-arch implant-supported fixed dental prostheses fabricated with a completely digital workflow: A clinical technique.

A digital method for delivering an immediately loaded interim complete-arch implant-supported prosthesis is described. Reference pins were used to accurately superimpose a postoperative scan with the scan bodies in place on a preoperative scan with the framework design, including the interocclusal relationship and the occlusal scheme. A prefabricated auxiliary device was used after surgery to record the position of the implants and after scanning to obtain an accurate transfer of the implant positions by means of a free software program, allowing an excellent fit of the fabricated prosthesis. This technique can help in the fabrication of an interim prosthesis with better fit and comfort and reduced chair time than conventional techniques.

Impact of design and length on the accuracy of closed tray transfer copings.

BACKGROUND: The aim of this study was to evaluate the accuracy of two closed-tray transfer copings for implant impressions (a new design vs. an old design) in two different lengths (short and long). MATERIAL AND METHODS: Four groups of transfer copings (NS - new short, NL - new long, OS - old short and OL - old long) were tested. An epoxy resin model was prepared of missing teeth 1.4, 1.5 and 1.6. Two Alpha-Bio analogues were placed in position of teeth 1.4 and 1.6, at a 10o angulation. Two calibrated operators took 10 closed-tray impressions for each group with polyether in a Rim-Lock impression tray. RESULTS: After measuring and comparing impressions, a significant difference was found between the two new transfer copings and the old short transfer coping. CONCLUSIONS: The new transfer coping design significantly improved impression accuracy. An adequate transfer coping design for the closed-tray impression technique can help to achieve clinically acceptable impressions for two-unit implant supported bridges. Key words:Closed tray, impression coping, transfer coping, implant impression.

Invasive Cervical Resorption: Clinical Management in the Anterior Zone.

According to the high number of articles published on invasive cervical resorption (ICR), this pathology, as commonly believed, is a more frequent form of cervical resorption. ICR is often misdiagnosed as internal resorption or caries, which leads to inappropriate treatment and even unnecessary tooth loss. Despite a correct diagnosis, the treatment of this type of hyperplastic invasive external resorption poses a challenge for the clinician. The Heithersay classification and the use of cone-beam computed tomographic imaging have increased our knowledge of the pathology and helped improve its prognosis. Nevertheless, there is no standard protocol for the treatment of this type of lesion. This article proposes a treatment protocol for ICR based on the pattern and location of resorption. Three treatment approaches (internal access, external access, and intentional replantation) are presented through 3 clinical cases.

Digital implant impressions by cone-beam computerized tomography: a pilot study.

OBJECTIVES: To evaluate the adjustment of structures designed from a digital impression of implants obtained by cone-beam computerized tomography (CBCT). MATERIALS AND METHODS: Thirty implants were placed in five edentulous mandibles of fresh cadaver heads, six per mandible. Special scan bodies were screwed in the implants and a CBCT was taken. DICOM images were converted to STL and digitally processed to obtain a digital model of the implants. A Cr-Co structure was designed and milled for each mandible, and the adjustment was assessed as in a real clinical situation: passivity while screwing, radiographic fitting, optical fitting, and probing. RESULTS: Good adjustment was found in three of the structures, and only slight discrepancies were found in the other two. CONCLUSION: Cone-beam computerized tomography might be a valid impression-taking method in full-mouth rehabilitations with implants. Further evaluations are needed with more implant and CBCT systems. The radiation dose might be considered when deciding to use this impression system. The types of patients appropriate for this treatment option should also be determined to fulfill the principles of the ALARA law.

Real-time MRI navigated US: role in diagnosis and guided biopsy of incidental breast lesions and axillary lymph nodes detected on breast MRI but not on second look US.

OBJECTIVES: To prospectively evaluate the accuracy of real-time ultrasound combined with supine-MRI using volume navigation technique (RtMR-US) in diagnosis and biopsy of incidental breast lesions (ILSM) and axillary lymph nodes (LNSM) suspicious of malignancy on contrast enhanced magnetic resonance imaging (CE-MRI). MATERIALS AND METHODS: Five hundred and seventy-seven women were examined using breast CE-MRI. Those with incidental breast lesions not identified after second-look ultrasound (US) were recruited for RtMR-US. Biopsy was performed in ILSM. Breast lesions were categorized with BI-RADS system and Fisher' exact test. Axillary lymph nodes morphology was described. To assess efficacy of RtMR-US, diagnostic accuracy, sensitivity, specificity, detection rate and Kappa index of conventional-US and RtMR-US were calculated. RESULTS: Forty-three lesions were detected on CE-MRI before navigation. Eighteen were carcinomas and 25 ILSM. Of these, 21 underwent a RtMR-US. Detection rate on RtMR-US (90.7%) was higher than on conventional-US (43%) (p<0.001). Agreement between both techniques was low (k=0.138). Twenty ILSM and 2 LNSM were biopsied. Sixty-five percent were benign (100% of BI-RADS3 and 56% of BI-RADS4-5). Diagnostic performance of RtMR-US identifying malignant nodules for overall lesions and for the subgroup of ILSM was respectively: sensitivity 96.3% and 100%, specificity 18.8% and 30.7%, positive predictive value 66.7% and 43.7%, negative predictive value 75% and 100%. In addition RtMR-US enabled biopsy of 2 metastatic lymph nodes. CONCLUSIONS: Real time-US with supine-MRI using a volume navigation technique increases the detection of ILSM. RtMR-US may be used to detect occult breast carcinomas and to assess cancer extension, preventing unnecessary MRI-guided biopsies and sentinel lymph node biopsies. Incidental lesions BI-RADS 3 non-detected on conventional-US are probably benign.

Horizontal root fracture treated with MTA, a case report with a 10-year follow-up.

Root fractures occur more frequently in fully erupted permanent teeth with closed apices in which the completely formed root is solidly supported in the bone and periodontium. The consequences can be complex because of combined damage to the pulp, dentine, cementum, bone, and periodontium. Management of horizontal root fractures and lateral luxation depends on several factors, with the result that various clinical modalities have been suggested. This case report describes the treatment and 10-year follow-up of two maxillary central incisors, one with horizontal root fracture and the other with lateral luxation, treated with mineral trioxide aggregate and root canal treatment, respectively.