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.

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.

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).

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.

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.

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.

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.

Influence of conventional and digital intraoral impressions on the fit of CAD/CAM-fabricated all-ceramic crowns

OBJECTIVES

To compare the fit of all-ceramic crowns fabricated from conventional silicone impressions with the fit of all-ceramic crowns fabricated from intraoral digital impressions.

METHODS

Thirty patients with 30 posterior teeth with a prosthetic demand were selected. Zirconia-based ceramic crowns were made using an intraoral digital impression system (Ultrafast Optical Sectioning technology) (digital group, D) and 2-step silicone impression technique (conventional group, C). To replicate the interface between the crown and the preparation, each crown was cemented on its corresponding clinical preparation using ultra-flow silicone. Each crown was embedded in resin to stabilize the registered interface. Specimens were sectioned in buccolingual orientation, and internal misfit was measured at different areas using stereomicroscopy (×40). Data was analysed using Student's t test and Mann-Whitney test (α = 0.05).

RESULTS

No statistically significant differences were found (P > 0.05) between two groups. The mean internal misfit and mean marginal misfit were 170.9 μm (SD = 119.4)/106.6 μm (SD = 69.6) for group D and 185.4 μm (SD = 112.1)/119.9 μm (SD = 59.9) for group C.

CONCLUSION

Ceramic crowns fabricated using an intraoral scanner are comparable to elastomer conventional impressions in terms of their marginal and internal fits. The mean marginal fit in both groups was within the limits of clinical acceptability.

CLINICAL SIGNIFICANCE

Impressions based on Ultrafast Optical Sectioning technology can be used for manufacturing ceramic crowns in a normal workflow, with the same results as silicone conventional impressions.

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.

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.

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.

Cemented and screw-retained implant-supported single-tooth restorations in the molar mandibular region: A retrospective comparison study after an observation period of 1 to 4 years

Objectives: The aim of this study was to evaluate the survival and compare the appearance of different mechanical and biological complications, in screw-retained and cemented-retained single-tooth implant-supported restorations localized in the molar mandibular region, over a period of 1 to 4 years. Material and Methods: A retrospective study was carried out with a total of eighty implant-supported restorations, which were placed in eighty patients for prosthetic rehabilitation of a mandibular molar. Forty patients were rehabilitated with a cemented-retained restoration and the other forty with a screw-retained restoration. The presence of the following complications was recorded for both types of prostheses: Fractures of the ceramic veneering, loosening screws, mucositis and peri-implantitis. Debonding of the restoration was analyzed in the cemented-retained restoration group. The clinical survival of crowns was analyzed with a Kaplan-Meier test and the clinical complications were compared, using a Student t test and Log-rank test. Results: 27 patients registered some complication. The average rate of complications was 37,5% for cemented-retained restorations and 30% for screw-retained restorations. The complications more common in the cemented-retained restoration were the presence of mucositis (14,87%), while in the screw-retained restorations was the loosening screw (20%). Student t test and Log-Rank test found significant differences (p=0,001) between the screw loosening and presence of mucositis. Conclusions: The cemented-retained restorations seem to prevent screw loosening, but the presence of cement seem to increase the complications around the soft tissues, however in the screw-retained restorations the presence of mucositis and peri-implantitis are lower than cemented-retained restorations. The incidence of fracture of ceramic veneering was similar in both groups.

Key words:Screw-retained restorations, cemented-retained restorations, screw loosening, peri-implant diseases and fracture ceramic veneering.

Zirconia in fixed prosthesis. A literature review

Statement of problem: Evidence is limited on the efficacy of zirconia-based fixed dental prostheses. Objective: To carry out a literature review of the behavior of zirconium oxide dental restorations. Material and Methods: This literature review searched the Pubmed, Scopus, Medline and Cochrane Library databases using key search words “zirconium oxide,” “zirconia,” “non-metal restorations,” “ceramic oxides,” “veneering ceramic,” “zirconia-based fixed dental prostheses”. Both in vivo and in vitro studies into zirconia-based prosthodontic restoration behavior were included. Results: Clinical studies have revealed a high rate of fracture for porcelain-veneered zirconia-based restorations that varies between 6% and 15% over a 3- to 5-year period, while for ceramo-metallic restorations the fracture rate ranges between 4 and 10% over ten years. These results provoke uncertainty as to the long-term prognosis for this material in the oral medium. The cause of veneering porcelain fractures is unknown but hypothetically they could be associated with bond failure between the veneer material and the zirconia sub-structure.

Key words:Veneering ceramic, zirconia-based ceramic restoration, crown, zirconia, tooth-supported fixed prosthesis.