Effect of wall thickness on shape accuracy of hollow zirconia artificial teeth fabricated by a 3D printer.

PURPOSE: This study aimed to analyze how the wall thickness of 3D-printed hollow zirconia teeth affects shape accuracy. METHODS: Datasets with measurement points were created for different artificial teeth resembling the mandibular right first molar (Geomagic Design X, 3D Systems). Reference distances were 9.8 mm for mesio-distal direction (M-D), 10.9 mm for bucco-lingual direction (B-L), 7.0 mm for MB-BB and DB-BB, and 4.5 mm for ML-LB and DL-LB. The outer geometry was identical for all artificial teeth with wall thicknesses of 0.30, 0.50, 0.75, and 1.00 mm. Twenty zirconia teeth were fabricated using a 3D printer (CeraFab 7500 Dental, Lithoz) for each group and sintered before support removal. After performing analog distance measurements using a micrometer screw, the digital distance measurements and angular deviations between measurement points on 3D scans were analyzed. Possible effects were investigated using nonparametric ANOVA, followed by Tukey's honest significant difference (HSD) test for multiple comparisons. RESULTS: The shape accuracy was acceptable for artificial teeth with wall thicknesses of ≥0.5 mm. The largest distance deviation was observed for a wall thickness of 0.3 mm. In particular, DB-BB showed a median deviation of >56.2 µm, which is significantly larger than that for other test groups, ranging from 7.4-9.5 µm (P < 0.05). In most cases, angular deviations were the largest for teeth with 0.3-mm wall thickness (11.6°) and remained below 5.0° for the other test groups. CONCLUSIONS: Acceptable accuracy was obtained for artificial teeth with wall thicknesses of at least 0.5 mm.

An effective artificial testing model to reliability experiments for electronic apex locator devices used in endodontic practice.

Background and Aim: This experimental study aimed to investigate the reliability of using electronic apex locator devices to determine the working length of artificial root canals. Materials and Methods: The experiments were performed using resin endoblocks and mandibular canine teeth (n = 20/group). After the same working length of root canal samples was provided, the teeth and artificial root canals were embedded in an alginate mold. The measurements with Root ZX® and Propex Pixi® apex locators were performed and recorded. The data were analyzed using SPSS software (SPSS V23; IBM Corp., Armonk, New York, USA) and the variance was set at P < 0.05. Results: There was no significant difference between the groups; mean distance from the actual working length using different apex locators (P = 0.633, P = 0.474), and endpoint positioning distributions (P = 0.591). Conclusion: The results indicate that the artificial model could be a laboratory method of determining the accuracy of apex locators and efficient calibration of devices before their clinical use.

Effect of retention hole designs in artificial teeth on failure resistance of the connection with thermoplastic resin.

This study aimed to evaluate the effect of retention hole designs in artificial teeth on failure resistance of the connection with a thermoplastic denture base resin. Artificial teeth with the following retention hole designs were attached to polyester and polyamide resins: no hole, vertical hole, horizontal hole, and vertical and horizontal holes. An artificial tooth with no hole attached to polymethyl methacrylate was prepared as the control. The load was applied until connection failure occurred between the artificial tooth and resin, and failure resistance was detected. Although the control showed the highest resistance, the artificial tooth with vertical and horizontal holes showed higher resistance than those with other retention hole designs in both thermoplastic resins. Providing vertical and horizontal retention holes in artificial teeth may be effective in improving failure resistance of the connection with thermoplastic resins.

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.

Evaluation of new endodontic tooth models in clinical education from the perspective of students and demonstrators.

BACKGROUND: The quality of root canal treatments performed by undergraduate students is often unsatisfactory questioning the current methods of teaching. Based on treatment errors made by students participating the endodontic courses at RWTH Aachen University (Germany), new radiopaque artificial root canal treatment models (DRSK RCT; incisor, premolar, molar) were designed and developed. The aim of the study was to evaluate these models by groups of students and demonstrators. METHODS: A total number of 60 students and seven demonstrators from a single institution (RWTH Aachen) participated in this study. They performed endodontic treatments on either initial versions of the DRSK RCT or modified versions. The initial versions were evaluated by students (n = 25) and demonstrators (n = 7). The obtained questionnaire was conducted as 7-point Likert-Scale covering the topics material properties, feeling while performing exercises and perception of its closeness to reality via 19 items (students) and 21 items (demonstrators). According to the evaluations several alterations were applied to the DRSK RCT, the whole study was repeated and evaluated by different students (n = 35) and the same demonstrators (n = 7). Additionally, the demonstrators blindly evaluated the quality of root canal treatments performed by the students (n = 35) on the modified DRSK RCT. Comparisons between the initial versions and the modified versions were calculated using Chi-squared tests. RESULTS: Students as well as demonstrators positively evaluated both variants of the DRSK RCT with especially high ratings in the overall evaluation. Students' rating of the pulp anatomy significantly increased from 5.4 ± 1.1 (mean ± SD) to 5.9 ± 0.9 (mean ± SD; p < 0.05) for the modified model. Likewise, students felt that the ability to flare root canals improved after alterations have been applied. Ratings significantly increased from 4.8 ± 1.6 (mean ± SD) to 5.6 ± 1.0 (mean ± SD; p < 0.05). CONCLUSION: The results indicate that the DRSK RCT is a promising candidate to be used as an alternative to extracted teeth or as an additional tool for improving dental education. However, some limitations of our analysis have to be considered.

[A Case of a Bronchial Foreign Body (Artificial Tooth) in the Right Middle Bronchus Without Respiratory Symptoms].

Patients with bronchial foreign bodies often present with subjective symptoms, mainly cough, and removing the foreign bodies is difficult. Bronchial foreign bodies are mostly located in the right lower bronchus, and rarely in the right middle bronchus. An 85-year-old man had no subjective symptoms. He aspirated an artificial tooth during dental treatment the day before visiting our clinic, and consulted his home doctor. He was admitted to our hospital because a chest radiograph indicated the presence of a foreign body in the right middle and lower lung field. Chest computed tomography showed that the bronchial foreign body was located in the right middle bronchus, and it was accompanied by an artifact in the circumference of the lesion, and it seemed to be the metal piece of an artificial tooth. Three-dimensional CT showed the root of the artificial tooth located in center side of the right middle bronchus, and, considering the invasiveness, we decided to remove the tooth by flexible bronchoscopy. The bronchoscopy revealed a metal piece occluding the right middle bronchus without granulation, and we could remove the tooth immediately by grasping the root of the tooth with alligator forceps. We experienced a case of a foreign body located in the right middle bronchus without respiratory symptoms. It is important to carry out image examinations, because elderly patients may not exhibit respiratory symptoms.

Horseradish peroxidase interacts with the cell wall peptidoglycans on oral bacteria.

Salivary peroxidase and myeloperoxidase are known to display antibacterial activity against oral microbes, and previous indications have pointed to the possibility that horseradish peroxidase (HRP) adsorbs onto the membrane of the major oral streptococci, Streptococcus mutans and Streptococcus sanguinis (S. sanguinis). However, the mechanism of interaction between HRP and the bacterial cell wall component is unclear. Dental plaques containing salivary glycoproteins and extracellular microbial products are visualized with 'dental plaque disclosing agent', and are controlled within dental therapy. However, current 'dental plaque disclosing agents' are difficult to evaluate with just dental plaques, since they stain and disclose not only dental plaques but also pellicle formed with salivary glycoproteins on a tooth surface. In this present study, we have demonstrated that HRP interacted with the cell wall component of the major gram-positive bacterial peptidoglycan, but not the major cell wall component of gram-negative bacteria lipopolysaccharide. Furthermore, we observed that the adsorbed HRP labeled with fluorescence was detected on the major oral gram-positive strains S. sanguinis and Streptococcus salivarius (S. salivarius), but not on a gram-negative strain, Escherichia coli (E. coli). Furthermore, we have demonstrated that the combination of HRP and chromogenic substrate clearly disclosed the dental plaques and the biofilm developed by S. sanguinis, S. salivarius and the major gram-postive bacteria Lactobacillus casei on tooth surfaces, and slightly disclosed the biofilm by E. coli. The combination of HRP and chromogenic substrate did not stain either the dental pellicle with the salivary glycoprotein mucin, or naked tooth surfaces. These results have suggested the possibility that the adsorption activity of HRP not only contributes to the evaluation of dental plaque, but that enzymatic activity of HRP may also contribute to improve dental hygiene.

Use of new scratch test and tensile test for evaluation of bond strength of selfadhesive flowable resin composite for repair of artificial tooth erosion.

The purpose of this study was to use a new scratch test and tensile test to evaluate the bond strength between artificial erosive enamel or dentin and self-adhesive resin composites as a coating material. Coronal enamel or dentin surface was exposed to an erosive cycle (artificial saliva [AS], pH:7.0 for 6.5 h and acidic carbonated beverages for 5 min, alternated 3 times per day) for the eroded-surface or stored in AS for the remineralized-surface. Two self-adhesive flowable resin composites, Fusio and LLB-CR6 (prototype), and a conventional flowable resin composite, BEAUTIFIL FLOW with self-etching primer system, Clearfil Mega Bond, were applied to enamel or dentin surfaces; and then the bond strengths were measured. For the eroded-surface, there were no significant differences in bonding strength among all materials, as assessed by the new scratch test. Thus, these self-adhesive flowable resin composites might be useful for coating materials on acid-eroded tooth surfaces.

The Effect of a Continuous Mechanical Polishing Protocol on Surface Roughness, Biofilm Adhesion, and Color Stability of Acrylic Resin Artificial Teeth.

PURPOSE: Acrylic resin properties are susceptible to change over the duration of use, thereby decreasing prosthesis longevity. To make the material less susceptible to the action of external agents such as stain-causing liquids and cleaning solutions, polishing procedures are recommended. A specific mechanical polishing procedure performed regularly was evaluated regarding the biofilm adhesion, surface roughness (Ra), color stability (ΔE), and mass changes in acrylic resin artificial teeth. MATERIALS AND METHODS: Sixty artificial teeth divided into two groups (n = 30) were immersed in distilled water (WT) and coffee (CF). These groups were then subdivided (n = 10) according to the type of polishing procedure administered: no polishing, biweekly polishing (once every 2 weeks) (pol 1), or monthly polishing (once a month) (pol 2), using aluminum oxide paste and a felt polishing wheel attached to an electric motor at a speed of 3000 rpm. Properties were evaluated at baseline and after 4, 8, 12, and 24 months of simulated immersion. At the end, the adhesion of Candida albicans and Streptococcus mutans multispecies biofilm in all groups was assessed. RESULTS: The CF group showed an increased Ra and weight, and a significantly greater ΔE compared to the WT group. The polishing procedure reduced Ra and minimized the stains caused by coffee, without losing mass, with the biweekly regime more effective than the monthly regime. Also, polishing reduced the adhesion of biofilm in the CF groups, again with the biweekly regime the most effective. CONCLUSIONS: When performed regularly, the mechanical polishing procedure tested reduces the changes in artificial teeth subjected to immersion in coffee, with the biweekly frequency most effective regarding the properties evaluated.

Rehabilitation with implant-supported fixed dental prostheses using digital duplication technique on customized artificial tooth, interim denture and implant surgical template: A case report / 대한치과보철학회지

Bone and soft tissue conditions are important for successful implant treatment. But, the placement itself is also very important. Implants which is installed in the wrong position result in the biological, esthetical and mechanical problems. In order to place an implant in the correct position, the final restoration and diagnostic wax-up should be considered prior to the surgery. If the artificial teeth for the interim denture are directly transferred from the diagnostic wax-up, the operator can try the form of diagnostic wax-up in the mouth. If the surgical template is produced by duplicating the interim denture, the implant can be placed in the planned position. In this case, the polymethyl methacrylate (PMMA) artificial tooth was precisely milled by the digital duplication of diagnostic wax-up. And interim denture was fabricated by using these milled teeth. After the patient adapted for a sufficient period, the implant was placed at the planned position with surgical template produced by duplicating the interim denture. After confirming sufficient osseointegration, the final prostheses were made to reflect the shape of diagnostic wax-up. Through this procedure, the satisfactory functional and esthetic outcome could be acquired.

Effect of Surface Treatments and Adhesive Materials on the Shear Bond Strength of Artificial Denture Teeth to Denture Base Resins.

AIM: The purpose of the current study was intended to evaluate the effect of different surface modifications and different adhesive materials on the shear bond strength of artificial teeth to heat-polymerized and thermoplastic denture base materials using different repair techniques. MATERIALS AND METHODS: Forty cross-linked artificial teeth used to construct different types of acrylic based denture prosthesis were selected to be bonded to two types of denture base materials, heat-polymerized acrylic resin denture base material, and thermoplastic acrylic resin denture base material. The specimens were divided into four subgroups according to the repair technique and adhesive material used. The base surfaces of all acrylic teeth then were moistened with monomer prior to bonding to the denture base specimens. Then, the specimens were tested using Universal Testing Machine for shear bond strength. The results were analyzed by using two-way analysis of variance (ANOVA) statistical analysis and multiple comparison tests, α ≤ 0.05. RESULTS: The effect of the types of denture base materials vs the surface conditioning methods displayed a statistically significant difference. CONCLUSION: This study concluded that monomer surface treatment of the bonded surface of artificial denture teeth and the use of cyanoacrylate adhesive followed by additional microwave polymerization displayed better shear bond strength when compared with other repair techniques. CLINICAL SIGNIFICANCE: Artificial teeth debonding from their denture bases is a common complication in dental practice. The current study evaluates different repairing techniques. Within the limitation of this study, the use of cyanoacrylate adhesive in combination with microwave polymerization is one of the best techniques of repairing denture teeth debonding.

Effect of Denture Tooth Material on Load Transmission Under Denture Bases.

OBJECTIVES: Pressure transmission under denture bases can vary depending on the denture tooth material. The aim of the present study was to evaluate pressure transmission under denture bases using denture teeth of different materials in direct and indirect tooth contacts. MATERIALS AND METHODS: In this in-vitro study, the pressure transmission generated by five types of denture teeth, including ceramic, nanocomposite, composite-acrylic resin, cross-linked acrylic resin, and polymethyl methacrylate (PMMA), under direct and indirect pressures was evaluated (n=10). The maximum pressure (MPa) was measured using a strain gauge. Data were statistically analyzed with one-way analysis of variance (ANOVA; α=0.05). RESULTS: The denture tooth material had a significant effect on pressure transmission under denture bases (P<0.001). Under direct load, ceramic and PMMA teeth exhibited the maximum and minimum pressures, respectively, contrary to indirect load (P<0.001). CONCLUSIONS: Pressure transmission under denture bases significantly varies with the use of different denture tooth materials. Acrylic teeth could be the most favorable choice to reduce the pressure beneath denture bases. Nanocomposite and acrylic resin-composite teeth may be used as alternatives.

Correlation between Visible Length of the Iris and the Length of the Maxillary Central Incisor Using Digital Image Analysis- A Pilot Study.

INTRODUCTION: Complete denture therapy is one such modality where science and art goes hand in hand. Selection of artificial teeth for completely edentulous patients is not easy in the absence of pre extraction records, because till date concrete guidelines do not exist. AIM: The purpose of this study was to determine if a correlation existed between the visible length of the iris and the length of the maxillary central incisor to potentially provide a guide for teeth selection. MATERIALS AND METHODS: A total of 20 Indian dental students consented to participate in the pilot study. Standardized digital images of the face revealing the eyes and component of teeth on smiling was captured using a digital camera. The digital measurements of the visible iris length (medial aperture height, tangential to iris) and the length of the maxillary central incisor from the zenith to the incisal edge were analysed using Adobe Photoshop creative cloud software. The data was statistically evaluated and results were tabulated. Karl Pearson's Coefficient of Correlation was utilized to detect if any association existed between the two variables. RESULTS: The mean value of length of central incisor was 10.39 mm and the mean value of the visible length of iris was found to be 12.9 mm. A Pearson correlation analysis revealed an r-value <0.3 indicating minimal association between the two variables with a p-value >0.01 (.322). CONCLUSION: On inference, the correlation between the visible iris length and that of maxillary central incisor were unable to produce a strong positive statistical association. However, an association factor between the two has been obtained. Deduction of 2.5 mm from the dimension of visible iris length will help in attaining the length of artificial maxillary central incisor tooth.

A novel anatomical ceramic root canal simulator for endodontic training.

INTRODUCTION: Endodontic therapy is often complicated and technically demanding. The aim of this study was to develop a reproducible biomimetic root canal model for pre-clinical and postgraduate endodontic training. MATERIAL AND METHODS: A specific ceramic shaping technique (3D printing and slip casting of a root canal mould) was developed to reproduce canal systems with the desired shape and complexity using a microporous hydroxyapatite (HAp)-based matrix. The microstructural morphology, pore size and porosity, as well as the Vickers microhardness of the ceramic simulators (CS) were assessed and were compared with natural dentin and commercial resin blocks. The reproducibility of the root canal shapes was assessed using the Dice-Sørensen similarity index. Endodontic treatments, from refitting the access cavity to obturation, were performed on the CS. Each step was controlled by radiography. RESULTS: Many properties of the CS were similar to those of natural dental roots, including the mineral component (HAp), porosity (20%, porous CS), pore size (3.4 ± 2.6 µm) and hardness (120.3 ± 18.4 HV). DISCUSSION: We showed that it is possible to reproduce the radio-opacity of a tooth and variations in root canal morphology. The endodontic treatments confirmed that the CS provided good tactile sensation during instrumentation and displayed suitable radiological behaviour. CONCLUSIONS: This novel anatomic root canal simulator is well suited for training undergraduate and postgraduate students in endodontic procedures.

A double blind randomized clinical trial comparing lingualized and fully bilateral balanced posterior occlusion for conventional complete dentures.

PURPOSE: A lingualized occlusion (LO) for complete dentures reduces lateral inferences and occlusal force contacts and direction; thus, LO is theorized to be more suitable for patients with compromised ridges than fully bilateral balanced articulation (FBBA). However, no studies have yet provided evidence to support LO in edentate patients with compromised alveolar ridges. The purpose of this study was to compare LO and FBBA in edentulous individuals with compromised ridges. METHODS: Sixty edentulous individuals were randomly allocated into groups and received dentures with either LO or FBBA. Following delivery, several denture-related satisfaction variables were measured using 100mm visual analogue scales; oral health-related quality of life (OHRQoL) was also assessed using the Oral Health Impact Profile (OHIP). Sub-group analyses of the effect of moderate and severe mandibular bone loss were also carried out. RESULTS: No significant differences were detected between LO and FBBA with the primary outcome. At 6 months, participants with severely atrophied mandibles and FBBA rated their satisfaction with retention of mandibular dentures significantly lower than those with LO (median LO: 86, FBBA: 58.5, p=0.03). They also had significantly lower OHRQoL for the domain of Pain (median LO: 4, FBBA: 5, p=0.02). General satisfaction and total OHIP scores significantly improved between baseline and 6 months only for the LO subjects with severely atrophied mandibles (satisfaction: p=0.003, OHIP total score: p=0.0007). CONCLUSIONS: The results indicate that the LO occlusal scheme with hard resin artificial teeth is more efficient for patients with severely resorbed mandibular ridges.

Alteração de cor em dentes de estoque após imersão em café e refrigerante / Color alteration in stock teeth after immersion in coffee and soft drink

Os dentes de estoque são dentes artificiais utilizados para a confecção de próteses, sendo que a resina acrílica tem sido o material de eleição devido às suas inúmeras vantagens, porém, assim como qualquer outro material, possui suas desvantagens, dentre elas: instabilidade de cor. O uso diário de bebidas ácidas em geral, como café e refrigerantes, tem tornando-se cada vez mais frequente, podendo comprometer a estética alterando a cor dos dentes artificiais. Assim, o avanço tecnológico tem almejado o melhoramento da composição dos dentes de estoque. Este estudo teve como objetivo analisar a alteração de cor de dentes de estoque de diferentes marcas após serem submetidos à submersão em dois líquidos com potencial de coramento. Foram selecionadas três marcas de dentes: Pop Dent (DentBras®), Biolux (Vipi®) e Trilux (Vipi®), sendo utilizados 15 incisivos centrais superiores direitos de cada marca. Tais dentes foram imersos em café e Coca-Cola®. A avaliação da alteração da cor foi feita por espectrofotometria, nos intervalos de 7, 15 e 30 dias, sendo os dados obtidos submetidos à análise estatística. Observou-se que os dentes Pop Dent (DentBras®) apresentaram alterações estatisticamente significantes nos três intervalos de tempo para os dois líquidos; os Biolux (Vipi®) apenas após 15 dias e os Trilux (Vipi®) evidenciaram alteração estatisticamente significante apenas com 30 dias para o café e 15 dias para a Coca-Cola®. O café e a Coca-Cola® apresentaram o potencial de manchamento semelhante um ao outro (AU).

Stock teeth are artificial teeth used to make prostheses, and acrylic resin has been the material of choice because of its numerous advantages, but, like any other material, it has its disadvantages, among them: color instability. The daily use of acidic beverages in general, as coffee and soft drinks, has become increasingly frequent and can compromise the aesthetics by altering the color of artificial teeth. So technological advance has been aiming the improvement of stock teeth composition. The aim of this study was to analyze color change of different brands of stock teeth after being submitted to submersion in two liquids with stain potential. Three different teeth brands were selected: Pop Dent (DentBras®), Biolux (Vipi®) and Trilux (Vipi®), 15 central superior incisors of each brand were used. These teeth were immersed in coffee and Coca-Cola®. The color change was evaluated by spectrophotometry, at intervals of 7, 15 and 30 days, the data was submitted to statistical analysis. It was observed that the Pop Dent teeth (DentBras®) presented statistically significant changes in the three time intervals for the two liquids; the Biolux (Vipi®) only after 15 days and the Trilux (Vipi®) showed statistically significant alteration only in 30 days for coffee and 15 days for Coca-Cola®. Coffee and CocaCola® showed the potential for staining similar to each other (AU).

Complete denture treatment using lingualized occlusion scheme at the edentulous patient with severely absorbed flat residual ridges: a case report

Many factors should be considered for successful denture treatment at edentulous patients: support, retention, stability, occlusion, esthetics, etc. The patient who has severely absorbed residual ridges, however, treatments are challenging to satisfy those factors. The dentures that use anatomic artificial teeth show good mastication efficiency and esthetics but, can easily lose stability at absorbed ridges. On the contrary, the dentures that use non-anatomic artificial teeth perform better stability but, lower masticatory efficiency and esthetics at absorbed ridges. The lingualized occlusion, using both anatomic and non-anatomic teeth, introduced for compromise those of the pros and cons. At lingualized occlusion, buccal cusps of the teeth do not contact on centric relation. Therefore, direction of the occlusal force towards lingually, then stability of dentures increases. This case report shows the results of the treatment flat residual ridges using complete dentures with ligualized occlusion to increase dentures stability and satisfactory of the patient.

Estabelecimento de uma proporção entre largura de dentes artificiais anteriores, medidos em curva e em linha reta / Establishing a ratio between the width of anterior artificial teeth measured in curved and straight configurations

Objetivo: estabelecer uma proporção única de redução entre a medida da largura dos seis dentes artificiais anteriores superiores, em curva e em linha reta. Material e métodos: foi utilizado um dispositivo pré-fabricado, simulando o plano de cera superior, no qual foram montados os dentes (Premium, Heraeus-Kulzer Inc. ­ Hanau, Alemanha) nos seguintes modelos: T2, O2, R2, S2, S4, O4, S6, R4, R6, T4 e T6. Em seguida, a largura em curva entre os dentes anteriores montados foi medida com uma régua flexível, tendo como referência a face distal dos caninos. A partir dos dados obtidos (mm) e dos valores das medidas fornecidos na carta molde do fabricante, realizou-se o cálculo da proporção entre essas duas medidas para cada modelo de dentes. Resultados: verificou-se redução entre a medida em curva e a medida em linha reta, variando de 4% a 19% para todos os tipos de modelos estudados. Assim, não foi possível estabelecer uma porcentagem padrão única de redução para todos os tipos de dentes do fabricante. Porém, agrupando-se a redução em milímetros, observou-se uma redução variável entre os modelos em curva e em linha reta: 2 mm para o modelo T2; 3 mm para os modelos O2, R2, S2 e S4; 4 mm para os modelos O4 e S6; 5 mm para os modelos R4, R6 e T4; e 9 mm para o modelo T6. Conclusão: é possível estabelecer uma redução aproximada (em mm) entre uma medição em curva e reta na seleção de dentes artificiais Premium/Heraeus-Kulzer.

Objective: this study aimed to establish a single rate reduction between the measurement of the width of the six artificial anterior upper teeth, in curved and straight configurations. Methods: for this, a prefabricated device simulating the upper wax rim was used and received artificial teeth (Premium, Heraeus-Kulzer Inc., Hanau, Germany) from T2, O2, R2, S2, S3, O4, S6, R4, R6, T4, and T6. Next, the width of the six anterior teeth in curvature was measured from the distal of both canines. After, based on the mold chart of the manufacturer, the ratio between the straight and curved configurations was generated. Results: there was a 4% to 19% in reduction between the curved and straight configurations. A single reduction percentage was not obtained for all tooth forms. However, the reductions were 2 mm for T2, 3 mm for O2, R2, S2 and S4; 4 mm for O4 and S6; 5 mm for R4, R6, and T4; and 9 mm for T6 models. Conclusion: it is possible to establish an approximated reduction (in mm) between the curved and straight configurations for Premium/Heraeus-Kulzer artificial teeth.

Bond Strength of Artificial Teeth Attached to a Microwave-Polymerized Denture Base Resin after Immersion in Disinfectant Solutions.

PURPOSE: To evaluate the bond strength between two types of acrylic resin teeth and a microwave denture base resin after immersion in disinfectant solutions for 180 days. MATERIALS AND METHODS: Eighty specimens made of acrylic resin teeth (Biotone and Biotone IPN) attached to a microwave polymerized denture base resin (Nature-Cryl MC) were divided into eight groups (n = 10) according to the treatment (distilled water-control, 2% chlorhexidine digluconate, 1% sodium hypochlorite and sodium perborate solution-Corega Tabs). The shear strength tests (MPa) were carried out using a universal testing machine with a 0.5 mm/min speed. Data analysis was performed using ANOVA and multiple comparison Student-Newman-Keuls post hoc test (α = 0.05). RESULTS: Biotone IPN showed similar results among the groups (distilled water, 8.25 ± 1.81 MPa; chlorhexidine, 7.81 ± 3.34 MPa; hypochlorite, 7.75 ± 3.72 MPa; and Corega Tabs, 7.58 ± 2.27 MPa, whereas Biotone showed significantly lower shear bond strength values for the groups immersed in Corega Tabs (5.25 ± 3.27 MPa) and chlorhexidine (6.08 ± 2.35 MPa). CONCLUSIONS: Soaking the dentures in 1% sodium hypochlorite could be recommended as a disinfectant solution for dentures fabricated with conventional acrylic resin denture teeth and microwave denture base resin. For dentures fabricated with IPN teeth and microwave denture base resin, all the soaking solutions evaluated in this study could be suggested to denture wearers.

Nova técnica para a seleção da largura dos dentes anterossuperiores utilizando a proporção áurea / New technique to determine the width of maxillary anterior teeth using the golden ratio

A seleção da largura dos dentes anterossuperiores na ausência de referências dentais é um procedimento complexo, sendo proposta uma avaliação da relação entre a largura dos seis dentes anteriores superiores, a distância entre a linha média dos incisivos centrais superiores à distal do canino superior e a distância das vertentes vestibulares dos caninos com as falanges média e proximal do dedo médio das mãos, bem como com a distância entre as comissuras bucais utilizando a proporção áurea. Foram utilizados o compasso de proporção áurea e o paquímetro digital para mensuração das falanges média e proximal do dedo médio, da distância entre as comissuras bucais e diretamente sobre os dentes. Foi posicionada uma tira de papel demarcando a distal do canino superior do lado direito e esquerdo, a linha média entre os incisivos centrais e as vertentes dos caninos superiores e, posteriormente, medidas com paquímetro digital. Foram avaliados 150 indivíduos, com idade entre 18 e 40 anos, sem alterações na face ou mãos, com sorrisos considerados estéticos, com ausência de giroversões, aparelho ortodôntico e próteses. A falange proximal do dedo médio pode ser utilizada para determinar a largura dos seis dentes anteriores superiores. As vertentes dos caninos, bem como a distância da linha média do incisivo central à distal do canino do mesmo lado, não tiveram correlação com a comissura bucal, falange proximal e média. Concluiu-se que a utilização da falange proximal do dedo médio é uma opção segura para a obtenção da largura dos seis dentes anteriores superiores (AU)

The selection of the width of maxillary anterior teeth in the absence of remaining teeth is a complex procedure. Thus it is indicated an evaluation of the relationship between the width of the six maxillary anterior teeth, the distance between maxillary central incisors' midline to the upper canine distal, and the distance of the vestibular slopes of upper canines, using the middle and proximal phalanges of the middle finger, as well as the distance between oral commissures using the golden ratio. Golden proportion compass and the digital calipers were used to measure the middle and proximal phalanges of the middle finger, the distance between oral commissures and to obtain direct measure of the teeth. A strip of paper was placed to mark: the maxillary canine distal on the right and left side, the midline between central incisors and the slopes of upper canine that were subsequently measured using a digital caliper. This study has evaluated 150 subjects, age between 18 and 40 years, with no facial or hand alterations, with aesthetics smiles and no teeth rotations, teeth braces or prostheses. The proximal phalange of the middle finger may be used to determine the width of the six maxillary anterior teeth. There was no correlation between the distance from the maxillary central incisors' midline to the upper canine distal (same side) and oral commissure, proximal and middle phalanges. It was concluded that the use of the proximal phalanx of the middle finger is a safe option to determine the width of the six maxillary anterior teeth (AU)