Targeting bonding protocols to increase the bond between acrylic resin or 3D printed denture bases and prefabricated or 3D printed denture teeth.

STATEMENT OF PROBLEM: The difference in chemical composition between denture base resin and denture teeth requires the development of bonding protocols that increase the union between the materials. PURPOSE: The purpose of this in vitro study was to evaluate the impact of different bonding protocols on the bond between heat-polymerized and 3-dimensionally (3D) printed acrylic resin denture bases and acrylic resin prefabricated and 3D printed artificial teeth. MATERIAL AND METHODS: Four types of artificial teeth were evaluated: prefabricated acrylic resin (VITA MFT) and 3D printed (Cosmos TEMP, PRIZMA 3D Bio Denture, and PrintaX AA Temp) bonded to 20×24-mm cylinders of heat-polymerized (VipiWave) and 3D printed (Cosmos Denture, PRIZMA 3D Bio Denture, and PrintaX BB Base) denture bases. Three bonding protocols were tested (n=20): mechanical retention with perforation + monomer (PT1), mechanical retention with perforation + airborne-particle abrasion with 50-µm aluminum oxide + monomer (PT2), and mechanical retention with perforation + Palabond (PT3). Half of the specimens in each group received 10 000 thermocycles and were then subjected to the bonding test at a crosshead speed of 1 mm/minute. The failure type was analyzed and scanning electron micrographs made. Additionally, surface roughness (Ra) and wettability (degree) were analyzed (n=15). ANOVA was used to evaluate the effect of the bonding protocol, and the Student t test was applied to compare the experimental groups with the control (α=.05). For type of failure, a descriptive analysis was carried out using absolute and relative frequency. The Kruskal-Wallis test was used to evaluate the surface changes (α=.05). RESULTS: Among the protocols, PT3 with in Yller and PT2 with Prizma had the highest bond strengths of the heat-polymerized denture base and 3D printed teeth (P<.05). When comparing the experimental groups with the control, PT3 and PT2 had greater union with the 3D printed denture base + 3D printed teeth (in Yller), with no difference from the heat-polymerized denture base + prefabricated teeth in acrylic resin. The treatment of the 3D printed tooth surfaces affected the surface roughness of Prizma (P<.001) and wettability (P<.001). CONCLUSIONS: To increase the bond between Yller 3D printed denture base + 3D printed teeth, a bonding protocol including mechanical retention with perforation + Palabond or mechanical retention with perforation + airborne-particle abrasion with aluminum oxide + monomer is indicated. For the other materials tested, further bonding protocols need to be investigated.

Effect of immersion in disinfectants on the color stability of denture base resins and artificial teeth obtained by 3D printing.

PURPOSE: To evaluate the effect of immersion in disinfecting solutions on the color stability of denture base resins and artificial teeth obtained by 3D printing. MATERIALS AND METHODS: Forty discs (15 × 3 mm) were obtained for each group: Lucitone 550 and Cosmos Denture 3D (denture base resins), Duralay and Cosmos TEMP 3D (artificial teeth resins). The discs were immersed in disinfectant solutions: Corega Tabs, 2% chlorhexidine digluconate, 0.25% sodium hypochlorite, and distilled water. Color measurements were obtained with a spectrophotometer before immersion in disinfectants and after the simulated periods of 6 and 12 months. Data (ΔE00 ) were submitted to mixed three-way ANOVA and Bonferroni post-test. RESULTS: For denture base resins, Cosmos Denture 3D showed greater color change regardless of the solution and immersion time. The immersion time of 6 months influenced the color change of the denture base resins regardless of the disinfectant solution. For the artificial teeth resins, the immersion time of 12 months showed a significant color change when compared to 6 months. Cosmos TEMP 3D showed greater color change for all solutions, except for 0.25% sodium hypochlorite. Duralay resin showed greater color change in 2% chlorhexidine, regardless of immersion time. CONCLUSIONS: For denture base resins, the immersion time significantly changed the color regardless of the solution. For artificial teeth resins, Cosmos TEMP 3D showed greater color changes in all solutions when compared to Duralay, except for 0.25% sodium hypochlorite. Chlorhexidine digluconate significantly changed the color of Duralay.

Evaluation of Shear Bond Strength Between Denture Teeth and 3D-Printed Denture Base Resin.

PURPOSE: The aim of this study was to evaluate the bond strength between two types of artificial teeth with a 3D-printed denture base resin using different bonding agents. MATERIALS AND METHODS: Two types of artificial teeth were evaluated: 3D-printed (Cosmos TEMP) and prefabricated polymethylmethacrylate (Biotone) bonded to cylinders (2.5 mm in height and 5 mm in diameter) of 3D-printed denture bases (Cosmos Denture designing by Meshmixer and printed by Flashforge Hunter DLP Resin 3D Printer). Two combinations between denture base and artificial teeth were eveluated: Cosmos Denture - Biotone, n = 30, and Cosmos Denture - Cosmos TEMP, n = 30. For each combination, the specimens were randomly distributed according to the bonding agent: (1) autopolymerized acrylic resin-Duralay, n = 10; (2) 3D-printed resin Cosmos TEMP, n = 10; and (3) methylmethacrylate monomer (MMA) + 3D-printed resin Cosmos TEMP, n = 10, totaling 60 specimens. The application of MMA was done conditioning the tooth surface for 180 seconds; the other agents were applied on the same surface. The virtual design of the 3D-printed resin teeth was obtained by scanning the first maxillary molar of the prefabricated teeth as the same protocol of cylinders. The control group (n = 10) was a conventional heat-polymerized denture base resin (Lucitone 550) bonded to the prefabricated resin teeth (Biotone). The shear bond tests were performed by applying a perpendicular force to the artificial tooth - denture base resin, through a chisel at 1 mm/min until failure. Two-way ANOVA and Bonferroni post hoc tests (α = 0.05) were used for multiple comparisons. RESULTS: For the Biotone tooth, the bond strength was significantly higher using MMA + Cosmos TEMP (10.04 MPa), and similar to the control (11.84 MPa, p = 0.484). For the 3D-printed tooth (Cosmos TEMP), the bond strength using the agents Cosmos TEMP (9.57 MPa) and MMA + Cosmos TEMP (12.72 MPa) were similar to the control (11.84 MPa, p = 0.169 and p = 1, respectively), but different from each other (p = 0.016). CONCLUSIONS: From the results, it is recommended to use: MMA + Cosmos TEMP bonding agent for the Biotone tooth; and Cosmos TEMP or MMA + Cosmos TEMP bonding agents for the Cosmos TEMP tooth, both attached to the 3D-printed denture resin Cosmos Denture.

Partially digital workflow for making complete-arch implant-supported fixed prostheses: A dental technique.

This article describes a technique for making complete-arch implant-supported fixed prostheses by using intraoral scanning and computer-aided design and computer-aided manufacturing (CAD-CAM) technology for the fabrication of a metal substructure and conventional processing for the prosthesis base. For this, a device was designed to accurately capture the position of multiple implants and the associated digitalized surgical guide, and the metal substructure was planned and milled directly in cobalt-chromium. The color of the gingiva and artificial teeth was selected by using the intraoral scanner software program, and the prosthesis base was processed conventionally. The straightforward methods used to fabricate the prostheses eliminated possible errors associated with conventional substructure casting and occlusal registration.

A new approach to endodontic access in anterior teeth: a pilot study / Uma nova abordagem para acesso endodôntico em dentes anteriores: estudo piloto

Introduction: The coronal opening is essential, during endodontic treatment, for direct access to the root canals. Usually, in the anterior teeth, endodontic access is achieved on the palatal/lingual surface, more specifically in the cingulum region. However, the lack of observation for dental positioning can lead to some accidents and complications, such as buccal perforations, causing esthetic damage and compromising the treatment. Objective: To evaluate the applicability of a new approach for performing coronal opening in anterior teeth, regarding the wear caused on the tooth crown, and to evaluate the ease of performing the new technique to minimize the risk of perforation. Material and method: Ten students (n=10) from the Improvement in Endodontics program participated in the present study. Twenty artificial teeth were used, which were upper, central incisors. Each participant performed two coronal openings. First, with no guidance (Group A - Conventional Technique) and afterward, a new opening, but with guidance with the spherical diamond tip placed parallel to the long axis of the tooth (Group B - Modified Technique). Result: The results showed that 90% of the participants considered the Modified Technique as having lower risk of accidents, as well as being easier for locating the pulp chamber. There was a statistical difference both in the measurement of the total area of wear and in the width, while there was no statistical difference in the height. Conclusion: Preliminary data collected with the survey were satisfactory for the Modified Technique. Statistically, it showed a favorable difference in relation to the area of wear and the width. However, in height there was no statistical difference.

Introdução: A abertura coronária é fundamental durante o tratamento endodôntico para um acesso direto aos canais radiculares. Em geral, em dentes anteriores, o acesso endodôntico é realizado na face palatina/lingual, mais especificamente em região de cíngulo. Entretanto, a falta de observação do posicionamento dentário pode levar a alguns acidentes e complicações, como as perfurações por vestibular, ocasionando dano estético e comprometendo o tratamento. Objetivo: Avaliar a aplicabilidade de uma nova abordagem de realização da abertura coronária em dentes anteriores, quanto ao desgaste ocasionado na coroa dentária, e avaliar a facilidade de execução da nova técnica para minimizar os riscos de perfurações. Material e método: Dez alunos (n=10) do curso de Aperfeiçoamento em Endodontia participaram do estudo. Foram utilizados vinte dentes artificiais, sendo eles incisivos centrais superiores. Cada participante realizou duas aberturas coronárias. Primeiramente sem nenhuma orientação (Grupo A - Técnica Convencional) e após, uma nova abertura, porém com orientação, com a ponta diamantada esférica posicionada paralelamente ao longo eixo do dente (Grupo B - Técnica Modificada). Resultado: Os resultados demonstraram que 90% dos participantes consideraram a Técnica Modificada como a de menor risco de acidentes e, ainda, de mais fácil localização da câmara pulpar. Houve diferença estatística tanto para a medida da área total de desgaste quanto para a largura, enquanto na altura não houve diferença estatística. Conclusão: Os dados preliminares coletados pelo questionário se mostraram satisfatórios para a Técnica Modificada. Estatisticamente, apresentou diferença favorável em relação à área de desgaste e largura, já em altura não houve diferença estatística.

The influence of the retention feature in artificial teeth on its attachment to the thermoplastic resin denture base / Influência da forma de retenção em dentes artificiais de resina acrílica na fixação na base de prótese termoplástica

Objective: Teeth play a crucial role in masticatory efficiency and esthetic harmony making rehabilitation of partially edentulous patients a challenge because of the limitations of conventional removable partial dentures. As a therapeutic alternative, thermoplastic polymers are used in current dental practice either for practical processing purposes or aesthetics. However, it is recognized that the bond between acrylic resin artificial teeth and thermoplastic polymers has no chemical interaction, and depends on retentive features added to the teeth. This study analyzed the efficacy of two retentive forms of features through compressive strength test and as a secondary outcome, fracture and displacement resistance test. Material and Methods: Three groups of samples each with 14 sets of acrylic teeth were compared when two retentive features, single hole and groove retention, and a control group with teeth without any specific form. The experimental unit consisted of six maxillary anterior teeth, positioned in a linear pattern into a polypropylene block, where each tooth was submitted to a static load until its removal, on a universal testing machine. Results: Those specimens with a groove retention presented larger resistance to displacement when compared to the other groups (p <0.05). This was emphasized by the fracture of the tooth tested, with part of the cervical portion remaining embed in the base, and not its displacement as with (or without) the retentive feature. Conclusion: In this study, the type of retention influenced significantly to a better retention considering teeth and thermoplastic polymer base. The data in this study indicates that a groove placed on the artificial tooth offers significantly better retention efficacy to the point where the displacement was only possible after its fracture (AU)

Objetivo: Os dentes são um fator essencial na eficiência mastigatória. A harmonia estética e a reabilitação dos indivíduos parcialmente dentados tornam-se um desafio, frente às limitações das próteses parciais removíveis convencionais. Como uma alternativa terapêutica, os polímeros termoplásticos são utilizados na odontologia contemporânea, tanto para o seu processamento prático como seu apelo estético. Entretanto, pouco se sabe a respeito da união entre a resina acrílica de dentes artificiais e resinas termoplásticas, assim como a influência dos mecanismos de retenção, uma vez que não há interação química entre eles. O objetivo deste estudo foi analisar duas formas de retenção de dentes de resina acrílica a bases de prótese de material termoplástico, por força compressiva e como desfecho secundário, teste de resistência a fratura e deslocamento dos dentes artificiais. Material e Métodos: O presente estudo analisou dois tipos diferentes de retenções: uma cavidade com único ponto e uma canaleta de mesial a distal; e como grupo controle, dentes colocados sem qualquer recurso específico. A unidade experimental consistiu de seis dentes superiores anteriores, posicionados em linha em um bloco de polipropileno. Em cada dente artificial foi aplicada força até a sua remoção, em uma máquina universal de ensaios. Resultados: Os resultados mostraram que a retenção com canaleta apresentou maior força de deslocamento, quando comparado com os outros grupos (p <0,05). Tal fato foi evidenciado pelo teste de fratura e deslocamento, no qual parte da porção cervical do dente artificial permaneceu unida à base, não ocorrendo o deslocamento com (ou sem) a retenção. Conclusão: Neste estudo, o tipo de retenção influenciou de forma significante a retenção de dentes artificiais de resina acrílica a bases de prótese termoplásticas. Os dados deste estudo indicam que a confecção da retenção em canaleta nos dentes artificiais oferece significante aumento na eficiência da retenção, ao ponto em que o deslocamento do dente ocorreu somente após sua fratura (AU).

Biomechanical properties of a 3D printing polymer for provisional restorations and artificial teeth.

OBJECTIVES: To characterize a resin-based polymer used for 3D printing (3D) provisional restorations and artificial teeth by evaluating relevant material's properties (flexural strength (σf), elastic modulus (E), water sorption (Wsp) and solubility (Wsl)) and biocompatibility, and comparing to a bis-acryl composite resin (BA) and a heat-cured acrylic resin (AR). METHODS: Structures were fabricated from 3D, BA and AR. Bar-shaped specimens (n = 30) were submitted to three-point flexure (in 37ºC water and constant displacement rate: 1 ± 0.3 mm/min) until fracture to calculate σf and E. Additional specimens (n = 30) were aged in 37ºC distilled water for six months before testing for σf. Disc-shaped specimens (n = 5) were dried in desiccators and oven until weight stability was reached, then they were immersed in distilled water for seven days, weighed and submitted to the drying process to obtain Wsp and Wsl. SRB and MTT assays were used to evaluate biocompatibility. Data were statistically analyzed using Kruskal Wallis, Student-Newman-Keuls (α = .05), and Weibull distribution. ANOVA and Tukey (α = .05) were used to evaluate the biocompatibility data. RESULTS: 3D structures showed higher σf than AR after aging. The BA showed the lowest values for σf and E, at baseline and after aging. All materials showed Wsp and Wsl values within the recommended standard values. AR structures showed lower cell viability (71.9%) than 3D (92.9%) and BA (90.8%) when using the SRB test. No difference was found when using MTT (p > .05). SIGNIFICANCE: The evaluated polymer-based 3D printing material showed adequate biomechanical behavior for using as a provisional restoration and artificial teeth.

Cyclic and torsional fatigue resistance of three different thermally treated nickel-titanium rotary instruments

Background: The aim of this study was to evaluate the cyclic fatigue and torsional fatigue resistance of three thermally treated rotary instruments, such as: Logic 2 25.05 (LOG 25.05), Edge Taper Platinum 25.06 (EDT 25.06) and ProTaper Gold 25.08 (PTG 25.08).Methods: A total of 60 rotary instruments of LOG 25.05, EDT 25.06 and PTG 25.08 were used (n=20). Cyclic fatigue tests were performed at 36°C using an artificial stainless steel canal with a 60ºangle and a 5-mm radius of curvature. The time (in seconds) and number of cycles to fracture (NCF) was recorded. The torsional test evaluated the torque and angle of rotation to failure at 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA and Holm-Sidak's tests for multiple comparison, the level of significance was set at 5%.Results: EDT 25.06 had highest cyclic fatigue resistance (time and NFC), followed by LOG 25.05 and PTG 25.08 (P<0.05). There were no significantly difference between LOG 25.05 and ETP 25.06 regarding the NCF (P>0.05). In relation the torsional test, the LOG 25.05 and ETP 25.06 presented similar torque (P>0.05). The PTG presented greater torque than the other groups (P<0.05). The PTG 25.08 presented the lowest angular rotation to fracture than the other groups (P<0.05). The SEM images demonstrated typical features of cyclic and torsional fracture.Conclusion: In conclusion, the LOG 25.05 and ETP 25.06 presented similar cyclic and torsional properties. The PTG 25.08 showed greater torsional strength.

Effect of conventional and rolled cigarette smoke on the colour of artificial teeth and effectiveness of hygiene protocols in removing pigmentation - An in vitro study.

Context: Artificial teeth are widely used in oral rehabilitation. Despite the benefits, they are more susceptible to colour changes, causing aesthetic problems. Aims: To evaluate the effect of conventional cigarette and straw smoke on the colour of artificial teeth and the effectiveness of hygiene protocols in removing pigmentation. Material and Methods: Acrylic resin incisors were divided into two groups (n = 50): Exposed to conventional cigarette and straw smoke. Regarding the effectiveness of hygiene protocols, the teeth were divided into ten subgroups with predetermined immersion times. The colour was measured with a colorimeter. The CIE values L* a* b* were recorded before and after exposure to smoke and after hygiene protocols. Statistical analysis used T-test of independent samples and two-way ANOVA with Bonferroni post-test (α = 0.05). Results: Conventional (16.16 ± 1.65) and straw (16.29 ± 1.95) cigarettes provided clinically unacceptable ΔE values, with no significant difference between them (P = 0.719). Conventional cigarettes promoted less luminosity (ΔL = -12.68 ± 1.28) (P < 0.001) and straw greater tendency to yellow (Δb = 11.00 ± 1.46) (P < 0.001). The hygiene protocols influenced the ΔE, ΔL, and Δb of the samples, depending on the type of smoke (P < 0.05). Conclusions: The conventional and rolled cigarette smoke promote an unacceptable colour change in artificial teeth. Hygiene protocols with the use of brushing, in isolation or in association with chemical solutions are more effective in removing pigmentation caused by both types of cigarettes compared to only the chemical solution.

Avaliação qualitativa de dentes artificiais de resina acrílica após escovação simulada / Qualitative evaluation of artificial acrylic resin teeth after simulated brushing

Introdução: os dentes artificiais de resina acrílica são amplamente utilizados na confecção de próteses, por apresentarem propriedades físicas, mecânicas e biológicas, além de características de fácil manuseio. No entanto, devido sua característica de baixa resistência à abrasão, a escovação pode levar à perda de massa dos dentes artificiais e aumento da rugosidade. Objetivo: avaliar de forma qualitativa a rugosidade superficial e polimento de dentes artificiais das marcas Hereaus Premium; Trilux e Vita, após período de 1 ano de escovação, com fotografias em Lupa Estereoscópica. Metodologia: para a realização deste estudo, serão utilizados 10 dentes artificiais de cada marca comercial (Trilux, Vita e Hereaus Premium). Os dentes serão fixados com resina ortoftálica em tubo de PVC de 15 mm de espessura. Para o teste de abrasão, será usada uma máquina de escovação simulada com escovas de dentes de cerdas macias e solução de pasta de dente. As imagens serão obtidas com câmera digital acoplada a lupa estereoscópica. A rugosidade superficial e o polimento serão analisados antes da escovação simulada e após 12 meses de escovação através das imagens. Resultados: após o teste de abrasão foi observado a presença de um desgaste superficial e/ou ranhuras na superfície dos dentes artificiais em todos os grupos. Porém não houve um padrão similar entre os corpos de prova de um mesmo grupo. Conclusão: Pode-se concluir que a escovação provocou o aumento da rugosidade superficial e alteração no polimento em todos os dentes artificiais utilizados.

Introduction: acrylic resin artificial teeth are widely used in the manufacture of dentures, as they have physical, mechanical and biological properties, in addition to easy handling characteristics. However, due to its characteristic of low abrasion resistance, brushing can lead to loss of mass of artificial teeth and increase in roughness. Objective: qualitatively evaluate the surface roughness and polishing of artificial teeth of Hereaus Premium brands; Trilux and Vita, after a 1-year brushing period, with photographs using a Stereoscopic Magnifying Glass. Methodology: for this study, 10 artificial teeth of each commercial brand will be used (Trilux, Vita and Hereaus Premium). Teeth will be fixed with orthophthalic resin in a 15 mm thick PVC tube. For the abrasion test, a simulated brushing machine with soft bristle toothbrushes and toothpaste solution will be used. Images will be obtained with a digital camera coupled to a stereoscopic magnifying glass. Surface roughness and polishing will be analyzed before simulated brushing and after 12 months of brushing through the images. Results: after the abrasion test, the presence of surface wear and/ or grooves on the surface of the artificial teeth was observed in all groups. However, there was no similar pattern between the specimens of the same group. Conclusion: it can be concluded that brushing caused an increase in surface roughness and change in polishing in all artificial teeth used.

The accuracy of electronic apex locators for determining working length: An in vitro study with artificial teeth.

This study aimed to determine the accuracy of four electronic apex locators (EALs) (I-Root, Propex Pixi, Novapex and Bassi iRoot Apex), using artificial mandibular and maxillary permanent molars. The root length (RL) from 40 artificial teeth was initially determined with Kerr hand files. Then, the electronic RL were obtained for the same root canals with each EAL, and the results were compared with those obtained using hand files. The accuracy of the EALs was determined through analysis of the divergences observed in relation to the lengths obtained with files. All EALs were effective for determining the RL in the artificial teeth, showing results similar to those obtained by hand. The Bassi iRoot Apex had higher accuracy (96.7%) than the Propex Pixi (89.1%) and Novapex (85.8%) (P < 0.05). Based on the results, all EALs tested had a similar performance, and artificial teeth may be used to determine the accuracy of these devices.

Morphometric evaluation of multirooted artificial teeth used for endodontic training / Avaliação morfométrica de dentes artificiais polirradiculares utilizados para treinamento endodôntico

Introduction Dental practice professionals encounter several urgency cases, mainly related to endodontic problems. To attend to these, professionals need extensive prior preclinical training, being one of the main difficulties the search for models that simulate dental morphology. Aim To compare the external morphometry of multirooted artificial teeth to literature. Material and method The artificial teeth (Upper First Premolar, Upper First Molar and Lower First Molar) were donated by the manufacturers: Fábrica de Sorrisos (FS) and IM do Brasil LTDA (IM), totaling 30 teeth. The total length of the tooth and root, height and buccal-palatal and mesial-distal dimensions of the crown were measured with a digital pachymeter. The data were placed in a spreadsheet and the statistical analysis was performed [ANOVA or Kruskal-Wallis and then, Dunnett's test (α=5%)]. Result The Upper Molar samples of the company Fábrica de Sorrisos presented all variables within the morphometric patterns described in the literature. The other dental groups presented statistically significant differences, maintaining or not a certain proportionality. Conclusion Of all the dental groups analyzed, the upper molar from the company Fábrica de Sorrisos was the only one that presented all the external morphometric aspects according to literature.

Introdução Dentro da prática odontológica, os profissionais podem receber diversos casos de urgência, principalmente relacionados a problemas endodônticos e, para atendê-los, há a necessidade de um extenso treinamento pré-clínico prévio, sendo uma das principais dificuldades a busca por modelos que simulem a morfologia dentária. Objetivo Comparar a morfometria de dentes artificiais polirradiculares à literatura. Material e método Os dentes artificiais (Primeiro Pré-molar Superior, Primeiro Molar Superior e Primeiro Molar Inferior) foram doados pelos fabricantes: Fábrica de Sorrisos (FS) e IM do Brasil Ltda. (IM), totalizando 30 dentes. Foi realizada mensuração do comprimento total do dente e o da raiz, da altura e das dimensões vestíbulo-palatina e mésio-distal da coroa, com paquímetro digital. Os dados foram dispostos em uma planilha de cálculo e realizou-se a análise estatística [ANOVA ou Kruskal-Wallis e, após, teste de Dunnett (α=5%)]. Resultado A amostra de molares superiores da empresa FS apresentou todas as variáveis dentro dos padrões morfométricos descritos na literatura. Os demais grupos dentários apresentaram diferenças estatisticamente significantes, mantendo ou não certa proporcionalidade. Conclusão De todos os grupos dentários pesquisados o molar superior da empresa FS foi o único que apresentou todos os aspectos morfométricos externos de acordo com os dados da literatura.

Percepção de docentes de Odontologia sobre o uso de dentes humanos como recurso educativo em atividades pré-clínicas / Perception of dental professorsabout the use of human teeth as an educational resource in pre-clinical activities

O estudo teve por objetivo avaliar a percepção de docentes de Odontologia em relação à utilização de dentes humanos extraídos e dentes artificiais em atividades pré-clínicas. Utilizou-se um questionário com perguntas objetivas e subjetivas aplicado aos professores cirurgiões-dentistas do Curso de Odontologia Centro Universitário de Anápolis -UniEVANGÉLICA. Dos 50 professores que correspondiam aos critérios de elegibilidade, obteve-se taxa de resposta de 76%. A média do tempo de formado dos docentesé de 20±9,7 anos e a média do tempo de docência de 17±10,5 anos. Quando questionados se dentes humanos deveriam ser utilizados como recursos educativos, a maioria (89,4%) respondeu que sim e em relação à aquisição de habilidades psicomotoras dos estudantes 68,4% acreditam que os dentes humanos são mais vantajosos. Citaram como desvantagem do uso aspectos relacionados à biossegurança (36,8%), dificuldade para obtenção dos dentes (21%), riscos de comercialização (15,7%) e aspectos éticos (15,7%). A maioria dos docentes de Odontologia do cursoavaliado entendem que o uso de dentes humanos em atividades pré-clínicas tem maior potencial pedagógico, além de favorecer o desenvolvimento de habilidades motoras em comparaçãoao uso de dentes artificiais (AU).

The present study aimed toassess the dental professor perception in relation to the use of extracted human teeth and artificial teeth in pre-clinical activities.A questionnaire was used with objective and subjective questions applied to professors of dental surgeons from the Dentistry Course Centro Universitário de Anápolis -UniEVANGÉLICA. Of the 50 professorswho met the eligibility criteria, a response rate of 76% was obtained. The average length of time for professorsto graduate is 20 ± 9.7 years andthe average teaching time is 17 ± 10.5 years. When asked whether human teeth should be used as educational resources, the majority (89.4%) answered yes, and concerning the acquisition of psychomotor skills by students, 68.4% believe that human teeth are more advantageous. He mentioned the disadvantage of using aspects related to biosafety (36.8%), difficulty in obtaining teeth (21%), risks of commercialization (15.7%), and ethical aspects (15.7%). Most dental professors in the evaluated course understand that the use of human teeth in pre-clinical activities has greater pedagogical potential, in addition to favoring the development of motor skills compared to the use of artificial teeth (AU).

In Vitro Effect of Acidic Challenges on the Physical Properties of Dental Prosthesis Artificial Teeth

Abstract Objective: To evaluate the effect of immersion and acid challenge with cola drink on color change (ΔE), Vickers hardness (VHN) and surface roughness (Ra) of artificial acrylic resin teeth. Material and Methods: The artificial teeth were divided into 6 groups (n= 8): TC (Trilux/Control), BC (Biotone/Control), TAC (Trilux/Acid challenge), BAC (Biotone/Acid challenge), TI (Trilux/Immersion) and BI (Biotone/Immersion). The teeth were embedded in acrylic resin and the labial side was serially polished to provide appropriate flat surface. The samples of TC, BC, TI, BI groups were immersed in artificial saliva and cola drink (coke) for 7 days, respectively. The acid challenge was performed with immersion of samples in coke for 5 min, and subsequently immersion in artificial saliva for 2h. This cycle was repeated at 4 times/day, during 7 days. The tests of VHN, ΔE and Ra were analyzed before and after the challenge and immersion groups. Data was analyzed by ANOVA, Tukey and T test (α = 0.05). Results: There was no difference in Ra values between groups after treatments. However, there was a decrease in VHN for all groups. BI (19.2 ± 0.3) presented significantly lower hardness than BAC (19.5 ± 0.9) and BC (20.2 ± 0.5). Groups BI (2.18 ± 0.41) and TI (1.50 ± 0.43) had statistically higher ΔE compared to the other groups. Conclusion: The hardness of resin teeth decreased after acid challenges, but the roughness surface was not affected. The color was more affected by the times of exposure in cola beverage and remineralization in artificial saliva, which were associated to the material degradation (AU).

Avaliação de dentes monorradiculares artificiais utilizados para treinamento endodôntico / Evaluation of artificial monoradicular teeth used for endodontic training

Introdução: É desafio do ensino pré-clínico em Endodontia fornecer aos alunos dentes artificiais que reproduzam a morfologia dos dentes humanos. Objetivo: Comparar a morfologia interna e externa de dentes artificiais monorradiculares com dados da literatura sobre dentes humanos. Material e método: Os dentes artificiais foram doados pelos fabricantes: Fábrica de Sorrisos, empresa A, (n=20), e IM do Brasil Ltda., empresa B, (n=20). Foi realizada mensuração do comprimento total do dente e da raiz, da altura, das dimensões vestibulopalatina e mesiodistal da coroa, com paquímetro digital. A descrição morfológica das raízes, coroas e câmaras pulpares foi realizada. A localização topográfica do forame apical principal foi avaliada após exploração dos canais com instrumento endodôntico tipo K #15 até este atingir visualmente o ápice radicular. Os dados foram dispostos em uma planilha de cálculo e realizou-se a análise estatística [ANOVA e pós-teste de Tukey (α=5%)]. Resultado: A amostra de caninos superiores da empresa B apresentou todas as variáveis dentro dos padrões morfométricos descritos na literatura. Em relação às morfologias interna e externa, a amostra de incisivos laterais superiores da empresa A foi a única a apresentar todas as variáveis dentro dos padrões descritos na literatura. Em relação à localização topográfica foraminal, os dentes da empresa A, assim como o canino inferior da empresa B, apresentaram tendência à posição distalizada e centralizada, vindo ao encontro da literatura. Conclusão: Nenhum dente artificial estudado apresentou total similaridade morfológica e morfométrica com a literatura analisada, diferindo em pelo menos uma das variáveis, sendo indicada aos fabricantes uma revisão dos seus modelos.

Introduction: It is a challenge of pre-clinical teaching in Endodontics to provide students with artificial teeth that reproduce the internal and external morphology of human teeth. Objective: To compare the internal and external morphology of single-rooted artificial teeth with data from the literature on human teeth. Material and method: The artificial teeth were donated from two companies: Fábrica de Sorrisos, company A, (n=20) and IM do Brasil Ltda, company B (n=20). Measurement of total tooth length, root, height, buccal-palatal and mesio-distal crown dimensions with digital caliper was performed. The morphological description of the roots, crown and pulp chamber was performed, the last one only after access. The topographic location of the main apical foramen was evaluated after canal exploration with a K #15 endodontic instrument until it visually reached the root apex. The data were arranged in a spreadsheet and statistical analysis was performed (ANOVA, followed by the Tukey post-test (α=5%)). Result: Regarding the morphometric parameters, the upper canine sample from company B presented all variables within the standards described in the literature. Regarding internal and external morphology, the sample of upper lateral incisors from Company A was the only one to present all variables within the standards described in the literature. Regarding the foraminal topographic location, the teeth of Company A, as well as the lower canine of company B, showed a tendency to the distalized and centralized position, in line with the literature. Conclusion: none of the artificial teeth studied showed total morphological and morphometric similarity with the control, differing in at least one of the variables, and a review of their models is indicated to the manufacturers.

Pre-clinical endodontic education outcomes between artificial versus extracted natural teeth: a systematic review.

AIM: To compare the educational outcomes using artificial teeth versus extracted teeth for pre-clinical endodontic training. DATA SOURCES: Literature searches of PubMed, Scopus, Cochrane Library, Trip Database, Web of Science and Open Grey databases were conducted from their inception until November 2018 with no language restriction. Hand searching of most likely relevant journals was performed. The review followed the PRISMA guidelines. STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: Studies that compared pre-clinical endodontic training using extracted teeth and artificial teeth were included. STUDY APPRAISAL AND SYNTHESIS METHODS: The quality of included studies was appraised by Joanna Briggs Institute Critical Appraisal tools. The findings were tabulated and summarized according to their outcomes with distinct narrative syntheses. RESULTS: Five studies were included. The component studies included 359 operators in total, mainly consisting of undergraduate students (97%, n = 349) and 10 endodontists (3%). Forty-seven per cent (n = 170) operated on artificial teeth only, whilst 19% (n = 67) worked primarily on extracted teeth, with the final treatment outcome being evaluated by independent observers using objective criteria. Operators in two studies (34%, n = 122) used both artificial teeth and ET and compared their experiences in surveys. Regarding technical outcomes, no significant differences between training with artificial teeth and extracted teeth were found, but the performance tended to be better in artificial teeth than extracted teeth. Operators trained solely on artificial teeth appeared to be adequately educated for subsequent root canal treatment (RCT) in the clinical setting. LIMITATIONS: Due to the scarcity of research on the topic overall, and the methodological variation between the studies, it was not possible to perform a quantitative analysis (meta-analysis). CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS: Based on the available evidence, the use of artificial teeth for pre-clinical endodontic training achieved similar educational outcomes compared to extracted teeth. However, the experiences reported by the operators diverged. Further studies assessing other artificial teeth available in the market testing other RCT procedures are necessary.

Physical properties of artificial teeth after immersion in liquid disinfectant soaps.

PURPOSE: To evaluate the hardness, roughness and color stability of artificial teeth after immersion in liquid disinfectant soaps. METHODS: Artificial teeth (Vipi Dent Plus, ArtiPlus and Biolux) were divided into four groups (n=15), according to the type of immersion solution: distilled water/control group (DW); liquid disinfectant soap Dettol (SD); liquid disinfectant soap Protex (SP); and liquid disinfectant soap Lifebuoy (SL). The immersion cycles occurred every day, for 8 hours at room temperature in each disinfectant solution, following immersion in distilled water for 16 hours at 37°C. All solutions were changed daily. Properties were evaluated after 0, 7, 14, 21 and 28 days of immersion. The data were analyzed with a mixed three-way ANOVA followed by the Bonferroni post-hoc test (α= 0.05). RESULTS: Vipi teeth presented significant reduction (P< 0.05) in hardness and roughness prior to 7 days of immersion in all solutions, including control group. These values, in general, were maintained during the 28 days. Biolux teeth, in general, did not present significant changes in hardness prior to immersion in any of the time intervals. The roughness of these teeth increased after 21 and 28 days of immersion (P< 0.05) in all the solutions. ArtiPlus teeth maintained stable roughness and hardness during the assessment period, regardless of the type of soap used. Color alterations were considered clinically acceptable. The liquid soaps may be an alternative for the disinfection of partial or total removable dentures. CLINICAL SIGNIFICANCE: The liquid disinfectant soaps tested did not significantly alter the hardness, roughness and color stability of the artificial teeth tested and may be an alternative for the disinfection of partial or total removable dentures.

Color Stability of Acrylic Resin Teeth After Immersion in Staining Solutions / Análisis del Cambio de Color de Dientes Artificiales Tras Inmersión en Soluciones Colorantes

ABSTRACT: The objective of this study was to evaluate the color alteration of four brands of artificial teeth (Art Plus, Trilux, Bionote and Biolux), after immersion in color solutions of coffee, red wine and urucum. We used 80 artificial teeth, which were standardized with 2 mm thickness. Then, they were subjected to finishing and polishing, and divided into 4 groups (n = 05), which were immersed in one of the 3 types of dye, plus distilled water (control). The samples were immersed daily for 4 hours, then they were removed, washed in tap water, dried with absorbent paper and immersed in distilled water for the subsequent hours in a biological glasshouse at 37 ºC, for 21 days. The evaluation of the color change was made in the periods of 0, 7, 14 and 21 days, by means of the tristimulus colorimeter. The data were subjected to the ANOVA and Tukey test with a 5 % significance. The results showed that the urucum was the substance that caused the greatest staining while the coffee and the wine did not show statistical difference. Regarding trademarks, Trilux presented a statistical difference compared to the other commercial brands, revealing colorimetric alteration only in the 14-day period. It was concluded that the composition of the artificial teeth, the type of pigmenting agent and the immersion time determine the color change.

RESUMEN: El objetivo de este estudio fue evaluar la alteración de color de cuatro marcas de dientes artificiales (Art Plus, Trilux, Bionote y Biolux), después de inmersión en soluciones colorantes de café, vino tinto y urucum. Se utilizaron 80 dientes artificiales, los cuales fueron estandarizados con 2 mm de espesor. En seguida, los mismos fueron sometidos al acabado y pulido, y divididos en 4 grupos (n = 5), los cuales fueron inmersos en uno de los 3 tipos de colorante, más agua destilada (control). Las muestras permanecieron inmersas diariamente durante 4 horas, luego fueron retiradas, lavadas en agua corriente, secas con papel absorbente e inmersas en agua destilada por las horas subsiguientes en invernadero biológico a 37 ºC, por 21 días. La evaluación del cambio de color se realizó en los períodos de 0, 7, 14 y 21 días, por medio del colorímetro tristimulo. Los datos fueron sometidos a la prueba ANOVA y Tukey con un 5 % de significancia. Los resultados demostraron que el urucum fue la sustancia que provocó mayor manchado mientras que el café y el vino no presentaron diferencia estadística. En cuanto a las marcas comerciales, el Trilux presentó una diferencia estadística en comparación con las otras marcas comerciales, revelando alteración colorimétrica sólo en el período de 14 días. Se concluyó que la composición de los dientes artificiales, el tipo de agente pigmentante y el tiempo de inmersión determinan el cambio de color.

The Development of Nonanatomic Denture Occlusion: Part III.

Part III of this four-part series about nonanatomic denture tooth development traces the evolution of this movement from the mid-1930s through the World War II era up to the early 1950s. By this time, the general preference for posterior denture occlusion had shifted from anatomic to nonanatomic teeth, and all the major denture tooth manufacturing companies listed at least one nonanatomic design in their inventories.

The Development of Nonanatomic Denture Occlusion: Part II.

This second part of a four-part series concerned with the development of nonanatomic denture occlusion follows nonanatomic tooth design from the time of Victor Sears' first nonanatomic tooth patent through the mid-1930s. Many of the designs featured in this series exhibit genius, while others are pure nonsense. Sears claimed that a new nonanatomic tooth design appeared every 9 months on average during the first 30 years of nonanatomic tooth production. Many current nonanatomic tooth patents are further refinements of those earlier designs. Part II reviews pioneering designs that appeared during the first dozen or so years of this paradigm shift in denture occlusion philosophy.