Assessment of different types of intra oral scanners and 3D printers on the accuracy of printed models: An in vitro study.

BACKGROUND: 3D printing technology is a reality in Dentistry and presents several ways to obtain a printed model. The aim of this study was to verify the influence of different types of intraoral scanners and 3D printers on the accuracy of printed models in comparison to plaster models obtained from conventional impressions. MATERIAL AND METHODS: A dental study model was used as the reference model and was molded with polyvinyl siloxane to produce the plaster models. It was also scanned with two types of intraoral scanners and the digital files were printed by two types of 3D printers. The plaster and printed models formed five groups (n=50), which were analyzed using linear measurements at six dimension sites. In order to test the equivalence in the precision of the measurements made in the reference model and in the different models of the experimental groups, the Schuirmann Two-One Sided t-test was applied. The trueness of the measurements of the experimental models was tested in comparison to those of the reference model by applying tests for paired data. In all statistical tests, the significance level of 5% (α = 0.05) was adopted. RESULTS: In relation to precision, all five groups presented similar and acceptable results. The trueness analysis indicated that both the printed and the plaster models had average measurements that were different from the reference model. CONCLUSIONS: It was concluded that the accuracy of printed and plaster models was impaired due to the trueness of the models. The type of printer influenced the accuracy of the printed models, while the type of scanner did not. The standardization of the method of obtaining printed models must be carried out in order to provide the production of quality models. However, there will be differences between the technologies. Key words:Dental models, three-dimensional printing, dimensional accuracy.

Accuracy of Casts Fabricated by Digital and Conventional Implant Impressions.

The purpose of this study was to compare the accuracy of stereolithographic casts (SCs) with those obtained using conventional implant impressions. An epoxy resin model containing dental implants was used as master model. Dental casts (n = 10) were fabricated through both conventional and digital implant impressions. The conventional casts (CCs), SCs, and the master model were digitized, and the accuracy was determined through a deviation analysis and linear measurements. Data were analyzed using paired Student t test with P < .05. The SCs showed higher deviation at the vestibular area (CC: 41 ± 28.87 µm; SC: 117 ± 36.83 µm) and lingual cusps (CC: 40.70 ± 19.79 µm; SC: 80 ± 42.95 µm) in comparison with CCs. No statistically significant difference was found for linear measurements of conventional and digital casts. The entire-arch accuracy was comparable between casts. However, SCs were less accurate at the cusp level in comparison with CCs.

A 5-week Non-Surgical Approach towards Denture Induced Hyperplasia.

BACKGROUND: Despite the standard approach towards denture-induced hyperplasia being surgery, as elderly population increases the systemic problems are carried along. Thus, surgery might be risky for patients with medical conditions. OBJECTIVE: In this report, a patient with severe inflammatory papillary hyperplasia, medical problems and dental fear was treated with a 5-week nonsurgical protocol. METHOD: Once in a week, the upper denture was relined with a zinc enolic paste, for four weeks. In the fifth week, the denture was relined with fast set polymethyl methacrylate resin instead of zinc enolic paste so that the material would last longer than only a week until the new pair of dentures was manufactured. RESULTS AND CONCLUSION: The generated pressure combined with antioxidant and anti-inflammatory properties of the paste led to the elimination of the inflammatory papillary hyperplasia completely, satisfying the patient and allowing the manufacturing of a new set of complete dentures.

CEREC Chairside System to Register and Design the Occlusion in Restorative Dentistry: A Systematic Literature Review.

OBJECTIVE: The aim of this review was to update the literature with regard to the digital methods available by CEREC Chairside system to register and design the occlusion, to report their efficacy and technical innovations in the field of Restorative Dentistry. A search strategy was performed using the key-words: "virtual articulator," or "CAD-CAM and occlusal recording," or "CAD-CAM and occlusion register," or "CAD-CAM and occlusal contacts," or "CAD-CAM and prosthesis." MATERIAL AND METHODS: Inclusion criteria comprised studies evaluating the use of digital methods available by CEREC System for occlusal registration and design during prosthodontics treatment. PubMed and Cochrane library and reference lists were searched up to January 2016. RESULTS: The search resulted in 280 articles after removing duplicates. Subsequently, 233 records were excluded and 49 studies were selected for reading in full. Eleven articles were considered eligible for the systematic review (4 in vitro and 7 clinical studies). CONCLUSION: Scientific evidence suggests that digital methods were accurate to register and design the occlusion of dental prostheses. Nevertheless, further clinical studies are required to establish a conclusion with regard to its accuracy in prosthodontics treatment. CLINICAL SIGNIFICANCE: Digital technologies allow the design of occlusal surfaces of CAD-CAM fabricated prostheses using innovative approaches. This systematic review aimed to update the literature to help dentists determine the most appropriate digital method to register and design the occlusal surface of CAD-CAM crowns. (J Esthet Restor Dent 28:208-220, 2016).

Análise crítica das construções protéticas, fixas e removíveis,sobre implantes em pacientes edentados: [revisão] / Critical analysis of the fixed and removable implant prosthesis on implants in edentulous patients: [review]

A osseointegração é, sem sombra de dúvida, a responsável pelo notável avanço tecnológico, mudança deconceitos filosóficos e condução de planejamentos voltados à reabilitação oral, como também, pela disseminaçãoe propagação dos conhecimentos, interferindo sobremaneira nas demais áreas da Odontologia contemporânea.Os implantes osseointegrados são cada vez mais utilizados para substituir dentes perdidos em várias situações, desde a perda de um único dente até em casos de completo edentulismo. A reabilitação de pacientes desdentados com próteses fixas ou overdentures removíveis é um processo complexo e desafiador. Existem fatores cruciais para a decisão de uma prótese fixa ou removível para se obter estética, fonética, promover conforto e função. Além disso, o resultado do tratamento está relacionado à taxa de sobrevivência dos implantes, à manutenção do osso marginal, à saúde do tecido periimplantar, à longevidade dos componentes protéticos e da prótese em si. Esse estudo buscou analisar as vantagens e desvantagens das reabilitações protéticas sobre implantes, fixas e removíveis, para pacientes totalmente desdentados.

Doubtless, osseointegration is the major responsible for the remarkable technological advance, changing philosophical concepts and guiding treatment plans related to oral rehabilitation. It also contributes to knowledge spread and diffusion, interfering in other areas of contemporary dentistry. Osseointegrated implants are widelyused to replace lost teeth in many situations, since the loss of a single tooth to completely edentulous archcases. Rehabilitation of edentulous patients by using fixed or removable implant-supported prostheses is a complex and challenging procedure. There are crucial factors involved at the decision of whether fixed or removable implant prosthesis should be planned to acquire optimal esthetics, phonetics, comfort, and function. In addition, the treatment result is related to implant survival, crest bone loss, soft tissue health, prosthesis's components longevity and prosthesis longevity itself. The aim of the present study is analyze the advantages and disadvantages of prosthetic rehabilitation of completely edentulous patients with fixed or removable implants.

Effect of surface topography of implant abutments on retention of cemented single-tooth crowns.

This study investigated whether surface topography affects the retentive strength of cemented full crowns, comparing the effects of standard machined, sandblasted, and grooved implant abutments. Five metallic crowns per abutment type were cast and cemented with zinc phosphate. After 24 hours, the specimens were submitted to a tensile test. The retentive strength of the cemented crowns was affected by abutment surface topography. The sandblasted and grooved surface groups had approximately 2.4 times greater mean uniaxial retentive strength than the machined surface group (P < .001). The retentive strength of the sandblasted and grooved abutments was similar, despite marked differences in surface profiles and roughness parameters.

Accuracy of four transfer impression techniques for dental implants: a scanning electron microscopic analysis.

PURPOSE: The aim of this study was to evaluate, using scanning electron microscopy (SEM), the accuracy of four impression techniques for osseointegrated implants (with or without acrylic resin splinting and with irreversible hydrocolloid or polyvinyl siloxane [PVS] impression material). MATERIALS AND METHODS: A metal master model was made with three implant analogs and two prosthetic spaces. This model was used as the standard for all impressions. Two impression materials were used (irreversible hydrocolloid and PVS) and two transfer techniques were used (squared impression copings indexed by the impression material and squared impression copings splinted with acrylic resin). Four groups were therefore analyzed (n = 5): IH = irreversible hydrocolloid only, IHS = irreversible hydrocolloid + splint, P = PVS only, and PS = PVS + splint. A reference framework made with palladium-silver alloy over the UCLA abutment was created on the master model. The fit of this structure to the master model was used as a reference. SEM images of the front and side gaps between the abutments and the implant analogs were created and then measured using image analysis software. RESULTS: IH presented the largest misfit. The splinted impression copings generated a smaller marginal gap than the indexed material technique, irrespective of the impression material used. There was no significant difference between IHS, P, PS, and the reference (multivariate test, Wilks criteria). However, PS presented a standard deviation that was three times lower than those of the other groups, and its mean was closer to the reference. CONCLUSIONS: The IH impression technique was the least accurate technique. There was no difference between IHS, P, and PS techniques with regard to the reference constant. The impression techniques that used splinted impression copings generated more accurate casts, irrespective of the impression material.