Clinical study comparing the accuracy of interocclusal records, digitally obtained by three different devices.

OBJECTIVE: The aim of the present cross-sectional study was to compare the interocclusal contact records obtained by three different digital methods (intra- and extraoral digital scanners and T-Scan III system) with the conventional method (articulating paper). MATERIALS AND METHODS: Twenty-five healthy volunteers were selected. As a control group, maximum intercuspation occlusal contacts were registered and photographed from the patients with an 8 µm articulating paper. Then, intraoral conventional elastomer impressions were taken and after obtaining the corresponding plaster models of every patient they were scanned with an extraoral scanner (Zfx Evolution, Zimmer Biomet Dental) (group 1). Moreover, digital impressions were made with an intraoral scanner (Trios Color POD, Phibo, 3Shape) and contacts were also registered (group 2). Finally, T-Scan III records were made and stored for further analysis (group 3). Two previously calibrated examiners independently evaluated the interocclusal contacts from every group. Data was analyzed by using Kappa index test and Pearson's chi-square test. Diagnostic tests and ROC curve were also performed. RESULTS: Kappa interoperator index was 70.6% (better agreement). In Kappa intraoperator index, the best value was obtained in the intraoral scanner group (moderate agreement) and the worst with T-Scan III group (low agreement). ROC curve showed highest values in the intraoral scanner group (0.817) and lowest values in the T-Scan III group (0.613). CONCLUSION: Results suggest greater reliability to record occlusal contacts with the intraoral scanner. CLINICAL RELEVANCE: Intraoral scanners seem to be reliable in registering intermaxillary occlusal contacts when compared with the current gold standard.

Accuracy of digitization obtained from scannable and nonscannable elastomeric impression materials.

STATEMENT OF PROBLEM: Elastomeric impression materials have been marketed for optimizing direct digital acquisition without requiring a stone cast. The trueness and precision of the digitization of these new elastomeric impression materials are unclear. PURPOSE: The purpose of this in vitro study was to compare the trueness and precision of digital dental casts obtained from the direct digitization of 2 types of vinylsiloxanether (VSXE) impression materials by using a laboratory laser scanner. MATERIAL AND METHODS: Thirty-eight elastomeric impressions were made of a master die with a similar morphology to a premolar crown preparation. The impression materials were Identium (IDE) and Identium Scan (SCAN), designed for direct digitalization. Each impression was digitalized by using an optical scanner to create digital casts. A computer-aided design (CAD) reference model of trueness (CRM) was created and aligned to each digital cast for digital 3-dimensional discrepancy analysis. RESULTS: The mean ±standard deviation global trueness of IDE was 53 ±16 µm and that of SCAN was 46 ±3 µm. SCAN digital casts showed higher precision (58 ±5 µm) than IDE (69 ±18 µm) (P<.05). At the margin of the preparation and at the axial surfaces, SCAN models showed higher trueness (3 ±6 µm and 1 ±5 µm) than IDE (15 ±10 µm and 2 ±37 µm), respectively. CONCLUSIONS: Scannable impressions could be digitalized with higher global precision than conventional elastomeric materials. Higher trueness could be achieved in specific impression locations such as gingival areas or axial walls of preparations, where the light emitted by the scanner was not blocked.

Comparative study of all-ceramic crowns obtained from conventional and digital impressions: clinical findings.

OBJECTIVE: To compare clinical aspects of all-ceramic crowns fabricated from conventional and digital impressions. METHODS: Thirty patients with 30 posterior teeth with the need of a crown restoration were selected. Zirconia-based ceramic crowns were made using an intraoral digital impression system (TRIOS®, 3shape) and two-step silicone impression technique. Two external blinded operators evaluated the all-ceramic crowns. Five selection items were assessed of which four were clinical: "marginal fit," "occlusal contacts," "interproximal contact points," and "primary retention." Then, the last selection item "final selection" was assessed when the operators considering all the variables had to select which of the digital or conventional crown had the best clinical conditions. Data was analyzed using Kappa index test and the Pearson's chi-square test (α = 0.05). RESULTS: For the items marginal fit and interproximal contact points, moderate agreement between the two operators was described and significant differences were found between the two study groups. Conversely, for the variables primary retention and occlusal contacts, the agreement between the operators was fair and no significant differences were found. For the final selection, a substantial agreement was reached between the two operators and significant differences were found between the two groups (p < 0.05). CONCLUSION: In most cases and in a significant way, the digital crowns had better clinical conditions according to both evaluators. The digital crowns were statistically superior for the interproximal contact points and marginal fit. For the variables occlusal contacts and primary retention, no difference between the two groups was observed. CLINICAL SIGNIFICANCE: Digital intraoral impressions can be used for manufacturing ceramic crowns, with the same or better clinical results as conventional impressions.

Digital scanning for implant-supported fixed complete-arch dental prostheses for patients with epidermolysis bullosa: A case series evaluation.

STATEMENT OF PROBLEM: The treatment of patients with recessive dystrophic epidermolysis bullosa has been compromised in the past by the lack of oral therapeutic information and the use of conventional complete dentures. PURPOSE: The purpose of this clinical case series study was to describe a digital rehabilitation protocol involving computer-aided design and computer-aided manufacturing (CAD-CAM) techniques for the treatment of patients with recessive dystrophic epidermolysis bullosa and to follow up for 4 years the patients who underwent this treatment. MATERIAL AND METHODS: A case series analyzing implant survival, peri-implant tissue health, and patient satisfaction with the treatment received was made of 4 patients with recessive dystrophic epidermolysis bullosa. Bimaxillary fixed implant-supported complete-arch rehabilitation was carried out by using a digital protocol with CAD-CAM techniques. RESULTS: The implant survival rate was 100%, with a bleeding rate of 74.2% and an inflammation rate of 58.0%. Gingival stability was achieved in 77.4% of the patients, with gingival displacement in 22.6% of the implants. However, the probing depth was maintained between 1 and 3 mm in 96.7% of the implants placed. CONCLUSIONS: Fixed complete-arch implant-supported rehabilitation is a successful treatment for patients with epidermolysis. Digital intraoral scanning facilitates the treatment of patients with this condition and reduces the clinical complications associated with conventional impression techniques (ulceration, blistering, angular cheilitis, and so forth).

Original vs. non-original abutments for screw-retained single implant crowns: An in vitro evaluation of internal fit, mechanical behaviour and screw loosening.

OBJECTIVES: To assess the internal accuracy, mechanical behaviour under static load and screw loosening before and after cyclic loading of implant-supported crowns restored with original components or with two compatible non-original brands. MATERIALS AND METHODS: Sixty-three dental implants were divided into three groups (n = 21 each): Group 1 used original components, and groups 2 and 3 used non-original components. Internal accuracy was measured throughout a cross section of the sample groups (n = 8) using scanning electron microscopy (SEM) to evaluate the fit for implant-abutments, implant-crowns and crown-abutments. To evaluate load-bearing capacity, eight samples from each group were loaded until fracture according to ISO Norm 14801. The removal torque value (RTV) was evaluated in the screws connecting the crown with the abutment and the abutment with the implant before and after cyclic loading (2 x 106 cycles) in five samples from each group. The data were analysed using the Kruskal-Wallis test (p < 0.05). RESULTS: Statistically significant differences were found among the mean crown-abutment gaps measured in Group 1 (9.3 µm), Group 2 (45.4 µm) and Group 3 (44.9 µm). Higher values for mean load-bearing capacity were found in Group 1 (1,098 N) than in groups 2 and 3 (1,057 and 973 N, respectively); however, these differences were not statistically significant. Original abutment-implant screws exhibited lower percentages of torque reduction than the non-originals. CONCLUSIONS: Enhanced fit is expected when original components are used. The original abutments exhibited lower percentages of torque reduction after cyclic loading than non-originals.

Intraoral versus extraoral digital occlusal records: a pilot study.

The aim of the present pilot study was to analyze the reliability of interocclusal contact records generated with an intraoral scanner (TRIOS Standard) and an extraoral scanner (Zfx Evolution). Ten patients were selected. The number of occlusal contacts was first determined with the conventional method using 8-µm articulating paper (gold standard) (control). These conventional records were then compared with the intra- and extraoral digital records. Diagnostics tests (sensitivity, specificity, predictive values for positives and negatives), receiver operating characteristic (ROC) curve, and Cohen's kappa coefficient were performed to analyze the data. The kappa index of the extraoral scanner (40.7%) was considered to be 'moderate,' and better than that of the intraoral scanner (26.1%), which was considered to be 'low.' The extraoral scanner showed better results in the diagnostic test and in the ROC curve. The first results suggest that the extraoral scanner is more reliable for recording occlusal contacts than the intraoral scanner.

Fixed dental prostheses with vertical tooth preparations without finish lines: A report of two patients.

Tooth abutments can be prepared to receive fixed dental prostheses with different types of finish lines. The literature reports different complications arising from tooth preparation techniques, including gingival recession. Vertical preparation without a finish line is a technique whereby the abutments are prepared by introducing a diamond rotary instrument into the sulcus to eliminate the cementoenamel junction and to create a new prosthetic cementoenamel junction determined by the prosthetic margin. This article describes 2 patients whose dental abutments were prepared to receive ceramic restorations using vertical preparation without a finish line.

Influence of customized over-scan body rings on the intraoral scanning effectiveness of a multiple implant edentulous mandibular model.

OBJECTIVES: To evaluate the effectiveness of intraoral scanning with identical multiple implant scan bodies (ISB) using customized over scan body rings (COR) as an auxiliary system. METHODS: Six printed rings with different diameters and shapes were attached at different levels to each identical ISB of an edentulous mandibular master model. The master model was scanned using an intraoral scanner (Primescan CEREC) until valid digital models for the COR group (n=10) and for the unmodified ISB (UN) group (n=10) were obtained. The total scanning times and the number of rescans required was registered. To assess differences between scanning efficiency the Student T-test and Mann Whitney U-Test were applied. A Coordinate Measuring Machine (CMM) was used to register the reference model. To evaluate accuracy discrepancies between the test scans (n=20) and the reference model, Geomagic Control X was used. Mann Whitney U-test was applied to calculate statistically significant differences. RESULTS: To achieve a valid model, an average of 4.70 rescans / repetitions were required for the UN group, whereas for the COR group required an average of 1.40 rescans (p<.001). Mean total scanning time was 201.10 s and 542.40 s for the COR and UN group, respectively (p=.001). No statistically significant differences were found between the groups in terms of accuracy (p>.05) with respectively COR and UN values; mean linear trueness 34.38 µm and 31.14 µm, mean linear precision 22.94 µm and 18.51 µm, mean angular trueness 0.12° and 0.14°, mean angular precision 0.075° and 0.08°. CONCLUSION: The use of the COR system may increase the scanning efficiency of multiple implants with similar ISBs without impacting the accuracy.

Ceramic veneers on central incisors without finish line using bopt in a case with gingival asymmetry.

OBJECTIVES: This clinical case report describes the rehabilitation of central incisors with veneers in a patient with gingival asymmetry. The teeth were prepared without finish line, applying BOPT concepts to correct asymmetry, and obtained a harmoniously integrated restoration with optimal periodontal health. CLINICAL IMPLICATIONS: Biologically oriented preparation technique (vertical or "feather edge" preparation) was used to obtain gingival symmetry. Teeth were prepared without horizontal finish line to achieve correct emergence, soft tissue adaptation and stabilization, while maintaining biological space, both at the provisional restoration stage and later when definitive restorations were placed. To perform the technique correctly, it is essential to perform adequate periodontal diagnosis to verify the space available between the bone crest and the future margin of the restoration. CONCLUSIONS: It is possible to correct gingival asymmetry by performing dental preparation without finish line providing a correct periodontal analysis is first performed, which will contribute to successful soft tissue stabilization. CLINICAL SIGNIFICANCE: Beyond of all the prosthodontic preparation techniques, knowledge of B.O.P.T. (Biological Oriented Preparation Technique) allows us to achieve predictable and consistent results in terms of periodontal health and gingiva architecture surrounding ceramic veneers. Nevertheless long term studies are necessary to ensure the benefits of this techniques. Key words:Gingival margin, emergence profile, biologically oriented preparation technique.

Endodontic re-treatment and restorative treatment of a dens invaginatus type II through new technologies.

BACKGROUND: The complex anatomy of dens invaginatus makes access cavity to root canal system difficult, which has an impact on the prognosis of these teeth. A novel technique, based on new technologies, is proposed to make access cavity conservative and guided with minimal dental structure lost. MATERIAL AND METHODS: This case report shows the root canal retreatment and the endodontic surgery of a dens invaginatus type II in a left lateral upper incisor previously treated which was affected by a chronic apical abscess and an apical fracture. A Cone Beam Computed Tomography was performed to better diagnosis the dental anatomy. An intraoral scan was performed to get a digital 3D model. A computer-guided implant planning software was used to plan the access cavity and design the splint guided. Finally, the clinical crown was restored by a resin nanoceramic veneer made by a chairside system made up of an intraoral scanning unit and a grinding unit. Last, the authors carried through the endodontic surgery to extract the apical fractured fragment. RESULTS: Follow-up appointments at 6, 12 and 18 months showed a radiographic reduction of the periapical lesion and absence of clinical signs. CONCLUSIONS: The splint guide allowed a guided and conservative access cavity to root canal system. It facilitates the root canal retreatment and improves the prognosis of the teeth with dental malformations. Key words:CAD-CAM, Cone-Beam Computed Tomography, dens in dente, dens invaginatus, dental pulp cavity, endodontics.

Comparative in vitro study of two methods for gingival biotype assessment.

BACKGROUND: The gingival thickness seems to have an important role in different dental treatments. There are different methods of quantifying this thickness, but it is not known which of them can be the most effective. The objective to assess the accuracy of two different methods for gingival thickness measurement: the transgingival needle probing (TGNP) and the tension-free caliper (TFC) in an in vitro model, by comparing them with direct physical measurements (reference standard). MATERIAL AND METHODS: Gingival thickness (GT) was evaluated in 27 female pigs with four implant sites 1, 2 and 3mm from the gingival margin with three different methods: 1) transgingival needle probing 2) tension-free caliper and 3) Direct visualization after making a incision in the mucosa and measuring GT with a periodontal probe. Wilcoxon test for paired samples were used with a confident level of 95%. RESULTS: A total of 324 points were measured, 59% of the sites presented a thin biotype with DV, it was correctly assessed with the TGNP in 84% of the times and in 86% with the TFC. 41% of the sample presented thick biotype, 76% was the percentage measured with the TGNP and 0% of the sites evaluated with TFC resulted in this biotype. CONCLUSIONS: Transgingival needle probing constitutes an accurate method when measuring GT at different levels. Tension free caliper is not a good tool for assessing the gingival biotype as long as it is unable to predict thick biotype. Key words:Periodontal Biotype, Gingival Thickness, Periodontal Tissue and Diagnosis.

Evaluation of the Mechanical Behavior and Marginal Accuracy of Stock and Laser-Sintered Implant Abutments.

PURPOSE: The aim of this study was to evaluate the marginal accuracy and mechanical behavior of implant-supported crowns restored with original stock abutments and nonoriginal computer-aided design/computer-assisted manufacture laser-sintered abutments. MATERIALS AND METHODS: A total of 26 implants were divided in two groups (n = 13 each) as follows: implants connected to original stock abutments (OS) and implants connected to nonoriginal laser-sintered abutments (LS). Of these, 10 samples were cross-sectioned to measure the marginal accuracy under a scanning electron microscope. In addition, 16 samples were used to study the mechanical behavior. Two tests were performed: (1) static load and (2) dynamic load after thermocycling with artificial saliva. RESULTS: OS exhibited the best marginal accuracy; however, the LS gap was within the clinically acceptable range of marginal discrepancy. No significant differences were found in the mechanical tests. CONCLUSIONS: Both abutments are acceptable alternatives to restore implants, although the original abutments showed better fit than nonoriginals.

In Vitro Evaluation of Three Methods for the Retrieval of Fractured Screw Fragments from Dental Implants.

PURPOSE: To compare the effectiveness of different methods of fractured screw fragment retrieval from dental implants, comparing a conventional method (use of an exploration probe and ultrasonic tips) with two mechanical retrieval kits. MATERIALS AND METHODS: One hundred thirty-five screws in implant internal connections were fractured to test fragment retrieval comparing three methods: conventional method with the use of an explorer probe and ultrasonic tips (group CE), extraction with a mechanical kit with a guide cylinder (group MK1), and extraction with a mechanical kit without a guide cylinder (group MK2). Extraction success and retrieval times for each method, as well as success and retrieval times in relation to fracture depth-coronal, middle, or apical-were analyzed by means of chi-square, Fisher exact, Kruskal-Wallis, and Mann-Whitney tests (P < .05). The integrity of implant internal threads was also analyzed. RESULTS: The extraction success rates for groups MK2, CE, and MK1 were 93.3%, 73.3%, and 20%, respectively. The mean ± SD extraction times were 2 minutes, 56 seconds ± 2 minutes, 9 seconds; 3 minutes, 15 seconds ± 1 minute, 48 seconds; and 13 minutes, 34 seconds ± 7 minutes, 25 seconds for groups MK2, CE, and MK1, respectively. Statistically significant differences were found in the number of fractured screws extracted and in the retrieval time. No significant differences were found for retrieval time or extraction success in relation to the depth of the fracture. CONCLUSION: The mechanical kit without the guide cylinder achieved the best results with respect to the number of screw fragments retrieved, retrieval time, and preservation of implant internal threads.

In vivo evaluation of three-dimensional of volumetric changes using a CAD/CAM chair-side system: Technical procedure.

An intraoral digital scanner in combination with specialized three-dimensional surface analysis software monitors volumetric changes to soft tissues or dental restorations. This technology can evaluate the success of a specific technique or medium- or long-term clinical outcomes in both clinical and research situations. This article describes how this technology was used to provide immediate chair-side data analysis without the help of specialized laboratory support. Key words:Intraoral scanner, CAD-CAM, best fit-method, surface tessellation language.

Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions based on wavefront sampling technology.

OBJECTIVE: The aim of this study was to compare the fit of ceramic crowns fabricated from conventional silicone impressions with the fit of ceramic crowns fabricated from intraoral digital impressions. METHODS: Twenty-five participants with 30 posterior teeth with a prosthetic demand were selected for the study. Two crowns were made for each preparation. One crown was fabricated from an intraoral digital impression system (IDI group) and the other crown was fabricated from a conventional two-step silicone impression (CI group). To replicate the interface between the crown and the preparation, each crown was cemented on its corresponding clinical preparation with ultra-flow silicone. Each crown was embedded in acrylic resin to stabilise the registered interface and then cut in 2mm thick slices in a buco-lingual orientation. The internal gap was determined as the vertical distance from the internal surface of the crown to the prepared tooth surface at four points (marginal gap, axial gap, crest gap, and occlusal fossa gap) using stereomicroscopy with a magnification of 40×. Data was analysed by using Wilcoxon signed rank test (α=0.05). RESULTS: Internal adaptation values were significantly affected by the impression technique (p=0.001). Mean marginal gap was 76.33 ± 65.32 µm for the crowns of the IDI group and 91.46 ± 72.17 µm for the CI group. CONCLUSION: All-ceramic crowns fabricated from intraoral digital impressions with wavefront sampling technology demonstrated better internal fit than crowns manufactured from silicone impressions. CLINICAL SIGNIFICANCE: Impressions obtained from an intraoral digital scanner based on wavefront sampling technology can be used for manufacturing ceramic crowns in the normal clinical practice with better results than conventional impressions with elastomers.

Implant-supported overdenture manufactured using CAD/CAM techniques to achieve horizontal path insertion between the primary and secondary structure: A clinical case report.

This report describes the case of an edentulous patient with an atrophic maxilla and severe class III malocclusion. Prosthetic rehabilitation was performed using CAD/CAM techniques for manufacturing an implant-supported overdenture with horizontal insertion. A vestibulo-lingual insertion overdenture is a precision prosthesis with a fixation system affording a good fit between the primary and secondary structure. Both structures exhibit passive horizontal adjustment. This treatment option requires the same number of implants as implant-supported fixed dentures. The horizontal assembly system prevents the prosthesis from loosening or moving in response to axial and non-axial forces. The technique was used to rehabilitate a patient presenting an atrophic upper maxilla, with the insertion of 8 implants. No complications were reported at follow-up 3, 6 and 12 months after fitting of the prosthesis. This system offers solutions to the clinical and laboratory complications associated with hybrid prostheses, concealing emergence of the chimneys and improving implant-prosthesis hygiene.

Diagnosis and endodontic treatment of type II dens invaginatus by using cone-beam computed tomography and splint guides for cavity access: a case report.

BACKGROUND AND OVERVIEW: Dens invaginatus (DI) is defined as a rare dental malformation. The inherent structural variants of this anatomic disorder make it difficult to perform conventional endodontic treatment procedures by means of a conservative access cavity. In this clinical case report, the authors describe the treatment of a type II DI by means of guided splints for cavity access. CASE DESCRIPTION: This is a clinical report of a case of type II DI in a maxillary lateral incisor. The authors established the diagnosis by means of cone-beam computed tomography (CBCT). The authors manufactured 3 splint guides from a Digital Imaging and Communications in Medicine file and a stereolithography file obtained from a plaster model of the patient by using software for guided implant placement, for access opening, and for locating the root canals. CONCLUSIONS: CBCT is an effective method for obtaining information about the root canal system in teeth with DI. In addition, guided implant surgery software is effective for manufacturing splint guides for endodontic treatment with conservative pulp chamber access. PRACTICAL IMPLICATIONS: Information obtained from CBCT allows the clinician to fabricate splint guides for minimally invasive access opening in this type of case, thus reducing the loss of dental tissue.

Immediate placement of single implant simultaneously with immediate loading in a fresh socket associated to periapical infection: A clinical case report.

Early restoration of the masticatory function, phonatory and aesthetics is some of the current goals of the therapy based on endosseous implants. Facing the classic protocols of implant insertion, which recommend a period of several months between extraction and implant placement, alternatives have been developed that demonstrate that immediate implant placement after tooth extraction permits adequate osseointegration, even in those cases where there is a periapical disease. The immediate restoration of implants after placement is a possibility where aesthetic requirements are high. This article presents a case with immediate implant placement and immediate loading of a first upper premolar with prior periapical pathology due to a vertical fracture. The immediate prosthetic was performed using the extracted crown, which is adapted to be attached to a titanium temporary abutment using a resin cement. After a 4 month healing period work began on the final prosthetic crown. The screw crown was made of zirconium oxide with a covering feldspathic ceramic. At the 12-month follow-up, there were no mechanical or biological complications. The patient gave high satisfaction marks for the overall treatment, giving visual analogue scale score of nine. Immediate post-extraction implants have arisen as an alternative to traditional implants on completely healed bone. Their main aim is to reduce treatment time and number of surgical procedures, along with other objectives such as reduced bone re-absorption and improved aesthetics. Key words:Post-extraction implants, immediate loading prosthetic, implant-retained prosthesis, periapical disease, vertical fracture.