Traditional versus simplified impression methods for complete dentures: critical appraisal of evidence / Método tradicional versus simplificado en impresiones para prótesis total removible: evaluación crítica de la evidencia Método tradicional versus simplificado

Abstract Introduction: Inspite of the great advances in dentistry, aging populations imply that there are still significant numbers of edentulous people worldwide. In most cases, implant-assisted prosthetic rehabilitation is the best solution. However, economic issues constrain access to this therapeutic approach, meaning that conventional removable prosthetics continue to be the most frequent treatment. In the removable denture making process, the so-called traditional method has been widely taught and used. It involves taking two impressions: a preliminary one followed by a definitive one (or functional). The simplified method constructs the prosthesis directly from the first impression obtained with a stock tray, without the need of a second impression. Purpose: To review the scientific evidence comparing both methods in terms of patient satisfaction, clinical quality, and masticatory performance and capacity. Results: No advantages have been found in favor of the traditional method regarding the four variables selected. Conclusions: According to the available information, the traditional method of taking impressions for complete removable dental prostheses does not provide significantly superior clinical results when compared to those obtained using the simplified method in terms of clinical quality, patient satisfaction, performance and masticatory capacity.

Resumen Introducción: Pese a los avances de la odontología, el fenómeno del envejecimiento de la población ha generado que la cantidad de personas desdentadas totales aún represente una cifra significativa. Los artificios protésicos implanto-asistidos constituyen, en la mayoría de los casos, la mejor alternativa rehabilitadora. Sin embargo, la variable económica surge como el principal impedimento para que los pacientes accedan a este recurso, y por este motivo, mantienen la prótesis total removible como una opción terapéutica. Para su confección, el método tradicional indica la necesidad de tomar dos impresiones: una preliminar y una definitiva o funcional. El método simplificado, confecciona la prótesis a partir de la primera impresión, obtenida con cubeta de stock. Objetivo: Revisar evidencia científica que compara ambos métodos en cuanto a las variables de: satisfacción del paciente, calidad clínica, rendimiento y capacidad masticatoria. Resultados: No se verifican ventajas a favor del método tradicional en relación a las variables estudiadas. Conclusiones: En concordancia con la información recabada, los resultados clínicos obtenidos mediante el método tradicional de toma de impresiones para prótesis totales no son significativamente superiores a los del método simplificado en relación a calidad clínica, satisfacción del paciente, rendimiento y capacidad masticatoria.

Precisión de los sistemas de impresión digital intraoral en odontología restauradora: Una revisión de la literatura / Accuracy of Intraoral Digital Impression Systems in Restorative Dentistry: A Review of the Literature

Abstract: La impresión intraoral permite al odontólogo obtener directamente los datos de las piezas dentales que se requiera rehabilitar, otorgándole mayor precisión y eliminando así de la fase clínica la toma de impresión y la fabricación del modelo, aspectos sensibles a errores. El objetivo de la presente revisión es identificar el sistema de impresión digital intraoral más preciso y además identificar los factores que afectan a la precisión de esta en odontología restauradora. Mediante una revisión bibliográfica con búsqueda en las bases de datos de PubMed y Embase se obtuvieron 153 artículos, luego de la evaluación cualitativa se incluyeron en la revisión 14 que cumplieron con los criterios de inclusión y exclusión. Se determinó que la experiencia del dentista, la convergencia en la preparación dental y la terminación cervical son determinantes al momento de la toma de impresión digital, sin embargo, el uso o no de polvo no es relevante. El sistema de impresión digital Lava C.O.S., iTero y True definition son los más precisos dependiendo siempre del tipo de rehabilitación a realizar.

Abstract: Digital impresión allows the dentist to directly obtain the data of the dental pieces that neet to be rehabilitated, giving it greater precisión and thus eliminating the impression and manufacturing of the dental model, error-sensitive aspects of the clinical phase. The aim of this review is to identify the most accurate intraoral digital impression system and identifiy the factors that affect the accuracy in the restorative dentistry. Through a bibliographic review with search in PubMed and Embase databases, 153 articles were obtained, after qualitative evaluation they were included in the revisión 14 that met the inclusion and exclusion criteria. It was determined that the experience of the dentist, the convergence in the dental preparation and the cervical termination are decisive at the accuracy of the digital impression, however, the use or not of dust is not relevant. The Lava C.O.S., iTero and True definition are the most accurate always depending on the type of rehabilitation to be performed.

Infection Control in the Dental Practice with Emphasis on Intraoral Scanners and Semi-Critical Complex Instruments / Control de Infecciones en la Práctica Dental Con Énfasis en Escáneres Intraorales e Instrumentos Complejos Semicríticos

ABSTRACT: We present an integrative review of the literature conducted to find and analyse specific measures for disinfection and/or sterilization of intraoral complex instruments, applicable to intraoral scanners. We performed a two-stage search in the PubMed/MEDLINE, SciELO, REDALYCS, and LILACS databases, and the Google Scholar website, which included full articles in Spanish, Portuguese, and English. The strategy associated the terms 'disinfection', 'biosecurity', 'decontamination', and (a) 'intraoral scanners', and (b) other 'semi-critical' intraoral complex instruments, according to the American Dental Association definition (e.g., 'turbine', etc). Strategy (a) produced just one outcome, whereas (b) produced nine articles, which only suggested low-level disinfectants.The lack of empirically based protocols that allow effective microbiological control makes it necessary to create a new categorization for these instruments when trying to comply with American Dental Association recommendations for dental practice.

RESUMEN: Presentamos una revisión integradora de la literatura realizada para encontrar y analizar medidas específicas de desinfección y / o esterilización de instrumentos complejos intraorales, aplicables a los escáneres intraorales. Realizamos una búsqueda en dos etapas en las bases de datos PubMed / MEDLINE, SciELO, REDALYCS y LILACS, y en el sitio web Google Scholar, que incluía artículos completos en español, portugués e inglés. La estrategia asoció los términos 'desinfección', 'bioseguridad', 'descontaminación' y (a) 'escáneres intraorales', y (b) otros instrumentos complejos intraorales 'semicríticos', según la definición de la Asociación Dental Ameri- cana (p. Ej., 'turbina', etc.). La estrategia (a) produjo un solo resultado, mientras que (b) produjo nueve artículos, que solo sugirieron desinfectantes de bajo nivel. La falta de protocolos de base empírica que permitan un control microbiológico efectivo hace necesario crear una nueva categorización para estos instrumentos, cuando se trata de cumplir con las recomendaciones de la Asociación Dental Americana para la práctica dental.

Effect of Gingival Retraction Method to Lateral Gingival Displacement Width

Abstract Objective: To analyze the efficacy of retraction cord with a hemostatic agent in comparison with retraction paste on lateral gingival displacement, to achieve the success of fixed dental prostheses (FDP). Material and Methods: Test samples included 32 teeth that required treatment with metal-porcelain FDP at RSKGM FKG Universitas Indonesia. Impressions were taken before the gingival retraction procedure. From the 32 samples, 16 teeth were retracted using a combination of retraction cord and hemostatic agent, whereas the other half were retracted with retraction paste. Impressions were then taken. The sample was made using cutting die. Lateral gingival displacement width was measured on die-cast using an optical microscope Results: The mean value of group A before gingival retraction was 0.1695 mm, and after gingival retraction was 0.4705 mm. The mean value of group B before gingival retraction was 0.1767 mm, and after gingival retraction was 0.3289 mm. Lateral gingival displacement width between a combination of cord retraction and hemostatic agent group in comparison with the retraction paste group showed a significant difference (p<0.001). The combination of cord retraction and hemostatic agent group showed higher mean value Conclusion: Gingival displacement width as a result of cord retraction with the hemostatic agent was larger compared to the retraction paste. Even though both of them are still considered to be effective in providing access for impression material.

Evaluation of the Accuracy of Conventional and Digital Methods of Obtaining Dental Impressions / Evaluación de la Exactitud de los Métodos Convencionales y Digitales de la Obtención de Impresiones Dentales

ABSTRACT: The aim of this study was to carry out a literature review on the accuracy of conventional and digital dental impression methods, as well as present the various three-dimensional intraoral scanning systems. A bibliographic search was carried out in PUBMED's main health database, in which works published between 2008 and 2018 were collected. Laboratory studies, case reports and systematic reviews were included, addressing topics that deal with conventional digital materials, impression and precision. Articles that did not evaluate impression materials, their behavior and techniques to obtain a good impression of oral structures were excluded. Through a review in the literature, obtained the following findings: the most critical stage in macking a dental prothesis is to take the dental impression. The conventional technique of impression consists of obtaining a negative copy of the intra-oral situation that will be poured into gypsum, obtaining a positive copy, on which the work will be carried out. Digital scanning systems were not superior to conventional moldings when comparing fidelity, accuracy and detail reproduction; in contrast, they were superior to conventional impression when considering clinical chair time, patient and operator preference, and patient comfort.

RESUMEN: El objetivo de este estudio consistió en realizar una revisión bibliográfica sobre la precisión de los métodos de moldeo dental convencionales y digitales, así como presentar los diversos sistemas de escaneo intraoral tridimensionales. Se realizó una búsqueda bibliográfica en la base de datos de salud principal de PUBMED en la cual se recopilaron trabajos publicados entre 2008 y 2018. Se incluyeron estudios de laboratorio, informes de casos y revisiones sistemáticas, abordando temas que tratan con materiales digitales convencionales, moldeo y precisión. Se excluyeron los artículos que no evaluaron los materiales de moldeo, su comportamiento y técnicas para obtener una buena impresión de las estructuras orales. A través de una revisión exhaustiva en la literatura, obtuvimos los siguientes hallazgos: el paso más crítico en la preparación de una pieza protésica es la impresión de la preparación. La técnica convencional de moldeo consiste en obtener una copia negativa de la situación intraoral que se verterá en el yeso, obteniendo una copia positiva, sobre la cual se realizará el trabajo. Resulta que los sistemas de escaneo digital no fueron superiores a las molduras convencionales al comparar la fidelidad, precisión y reproducción de detalles; en cambio, fueron superiores a las molduras convencionales al considerar el tiempo de trabajo clínico, la preferencia del paciente y del operador y la comodidad del paciente.

Superposición de modelos en 3D / 3D models overlay

Se superpusieron archivos digitales 3D de modelos dentales en un ordenador, con fines comparativos. Para lograr dicho objetivo se usaron 18 modelos dentales digitalizados por método de escaneo directo, en el Círculo Argentino de Odontología. El archivo exportable se dirigió por software de código abierto Meshlab, donde se observó exactitud, reproducibilidad e inalterabilidad de las muestras; dicho resultado determinó la importancia de difundir, a nivel institucional y particular, dicha práctica, considerando, en el diagnóstico, que las visualizaciones o mediciones directas sobre modelos estándar son, no solamente más imprecisas, sino que implican un mayor tiempo de rabajo.

Marginal and internal fit of zirconia copings obtained using different digital scanning methods

Abstract The objective of this study was to evaluate the marginal and internal fit of zirconia copings obtained with different digital scanning methods. A human mandibular first molar was set in a typodont with its adjacent and antagonist teeth and prepared for an all-ceramic crown. Digital impressions were made using an intraoral scanner (3Shape). Polyvinyl siloxane impressions and Type IV gypsum models were also obtained and scanned with a benchtop laboratory scanner (3Shape D700). Ten zirconia copings were fabricated for each group using CAD-CAM technology. The marginal and internal fit of the zirconia copings was assessed by the silicone replica technique. Four sections of each replica were obtained, and each section was evaluated at four points: marginal gap (MG), axial wall (AW), axio-occlusal edge (AO) and centro-occlusal wall (CO), using an image analyzing software. The data were submitted to one-way ANOVA and Tukey's test (α = 0.05). They showed statistically significant differences for MG, AO and CO. Regarding MG, intraoral scanning showed lower gap values, whereas gypsum model scanning showed higher gap values. Regarding AO and CO, intraoral digital scanning showed lower gap values. Polyvinyl siloxane impression scanning and gypsum model scanning showed higher gap values and were statistically similar. It can be concluded that intraoral digital scanning provided a lower mean gap value, in comparison with conventional impressions and gypsum casts scanned with a standard benchtop laboratory scanner.

Accuracy of face castings employing thermoplastic custom trays for facial molding

AIM: To evaluate the dimensional stability of a new facial molding technique using thermoplastic custom molding tray. METHODS: The designs established demarcation of facial anthropometrics landmarks, making linear measurements with a digital caliper. Facial molding was carried out using thermoplastic custom trays, constructing a facial plaster cast with the anthropometric landmarks already transferred by measuring the linear dimensions on the plaster cast and statistical analysis. RESULTS: All linear measurements in the palpebral and labial regions presented statistically significant distortions. Only one of the linear measurements from the orbital region did not demonstrate any significant distortion. The nasal region presented the least amount of distortion. CONCLUSIONS: Although statistically significant, distortions were due to the method of breathing and were considered to be clinically irrelevant. The reduction in the working time, the comfort provided to the patient and the dimensional accuracy of the plaster cast obtained by the facial molding technique using custom perforated molding tray suggest that this technique should be employed for making facial prostheses.

Effect of a cordless retraction paste on titanium surface: a topographic, chemical and biocompatibility evaluation

Good exposure of the preparation margins and haemostasis in the sulcular gingiva are necessary for accurate impressions to produce precise restorations. The use of cordless retraction paste material in implant dentistry is a relatively novel application. However, few studies have been conducted on the use of retraction pastes and their possible interaction with implant surfaces. Recent literature has described remnants on titanium implant surfaces and expressed the need for an assessment of the biocompatibility of the exposed surface (Chang et al.). This in vitro study evaluated the effect of a cordless gingival retraction paste on sterile titanium disks. Surface chemistry was determined using energy-dispersive X-ray spectroscopy (EDS), and further investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). After exposure to retraction paste, surface chemistry alterations were identified. A fibroblast cell line (L929) was exposed to the disks and the live/dead viability/cytotoxicity assay was used to determine any effects on the proliferation and health of cells. The disks exposed to the retraction paste showed fewer dead cells compared to the unexposed disks. This was statistically significant.

Moldagem dupla para prótese fixa utilizando uma silicona de condensação e um poliéter / Double impression for fixed denture using condensation silicon and a polyether: case report

Este estudo apresenta um caso clínico no qual visou-se estabelecer uma combinação entre as técnicas de moldagem de preparos cavitários mais utilizadas na clínica diária e seus respectivos materiais, por meio da utilização simultânea de uma silicona de condensação e de um poliéter durante a confecção de uma ponte fixa de 4 elementos, explicitando-se sua execução técnica. O paciente, leucoderma, 50 anos, compareceu à clinica do curso de atualização em Prótese Fixa, queixando-se de dificuldades mastigatórias e deficiências estéticas. Confeccionou-se então uma prótese fixa metalocerâmica de 4 elementos, composta de preparos cavitários do tipo coroa total sobre núcleo fundido no elemento 14 e tipo MOD com proteção de cúspides no elemento 16. Como o término cervical do preparo do elemento 14 localizou-se subgengivalmente em sua face vestibular e o do elemento 16 em toda a sua extensão, optou-se pela moldagem com casquete e um poliéter no elemento 14, conjuntamente com a pasta densa e a fluida de uma silicona de condensação no elemento 16. A adaptação das peças protéticas foi conferida por meio de um microscópio óptico. É possível obter-se moldagens de boa qualidade, lançando-se mão de técnicas relativamente simples e pouco agressivas aos tecidos gengivais do paciente durante a confecção de próteses fixas, combinando materiais diferentes em sua composição química, mas de uso consagrado na clínica diária.

This study presents a case report which aimed to establish a combination of cavity preparation impression techniques commonly used in dentistry and their material through the simultaneous use of a condensation silicone and a polyether during the production of fixed denture with four elements, explaining its technical implementation. The patient, caucasian, 50 years old, came to the clinical course in Fixed Prosthodontics, complaining of chewing difficulty and aesthetic deficiencies. A metal-ceramic fixed partial denture with four elements, consisting of a full crown type cavity preparation in element 14 and MOD-protected cusps type on the element 16. Since completion of the preparation of the element 14 was located subgingivally and the preparation of 16 was located supragingivally, an acrilyc resin impression coping was used as well as a polyether to mold element 14, combined to a condensation silicon at element 16. The adaptation of prosthetic parts was verified through an optical microscope. It is possible to obtain good impressions utilizing relatively simple techniques that are little aggressive to the gingival tissues of the patient during the manufacturing of fixed partial dentures by combining different materials in their chemical composition.

Single step approach to make diagnostic impressions of both the arches and face bow transfer: A novel technique.

Context: Mounting the maxillary and mandibular dentulous casts for Diagnostic purpose requires many steps (including making maxillary and mandibular impressions, face-bow transfer, and bite registration) or many appointments. A simple new technique of doing all of this together without compromising on the accuracy can save time over the conventional mounting procedure. Aim: To compare the accuracy of a new technique of a single-step diagnostic mounting procedure with that of the conventional diagnostic mounting procedure. Materials and Methods: Ten dentulous patients with the full complement of teeth and without any history of temporomandibular disorder and orthodontic treatment were selected for this study. A detachable metal triple tray to replace the fork part of the face bow fork that further could be attached to face bow was fabricated. Dual-arch impressions and face-bow transfer were made in these subjects using this modified triple tray. These mountings were compared with the ones done with the conventional mounting procedure. Five linear measurements (using stable reference points on the articulator and the cast) were made and the values obtained by both the methods were compared. Statistical Analysis: The Student's 't' test for statistical analysis was used in this study. Results: The measurement values obtained by the single-step method were almost similar to the ones obtained by the conventional method. The various mean measurements for the single step and conventional methods were 37.7 ± 6.8 and 38.5 ± 6.5 mm; 70.0 ± 4.4 and 70.1 ± 4.2 mm; 57.0 ± 4.9 and 57.3 ± 4.2 mm; 71.3 ± 4.5 and 71.0 ± 4.6 mm; and 58.7 ± 2.5 and 58.3 ± 2.3 mm; respectively. The differences between the values obtained by the conventional and single-step methods were not statistically significant. Conclusion: The single-step procedure of diagnostic mounting can be used as an alternative to the conventional method, without compromising the quality of mounting.

survey on cross infection hazards associated with dental impression recording

Infection control ideology, disinfection/ sterilization protocols and cross infection control has been a baseline requirement for every invasive procedure. Dental Impression recording a pre-requisite for all dental procedures could be a source of cross infection if the protocols are not known, understood, accepted or followed. Aim of this study was thus to assess through a questionnaire the base line knowledge of dental students and dental graduates regarding infection control measurements associated with dental impression recording. A total of 78 House surgeons and Final Year students who consented were included in the study. The filled a valid questionnaire identifying the Dental Impression recording related cross infection issues. SPSS 17.0 was used for statistical evaluation. It was inferred that 66.7% of study group felt that metallic impression trays and another 13% felt that disposable impression trays should be used to prevent cross contamination. It was an important finding that 93.6% of study group was aware of appropriate need of disposal of disposable impression trays however method of disposal were different. 100% study group was sending the impression out after washing or disinfecting them which were an incredible finding, however they should be encouraged for disinfection of impression. It was thus inferred from the results that though students and graduate are well aware of infection control procedures and are following them however structured infection control standards teaching can improve standard further

Surface detail reproduction and dimensional accuracy of stone models: influence of disinfectant solutions and alginate impression materials

This study compared the surface detail reproduction and dimensional accuracy of stone models obtained from molds disinfected with 2% sodium hypochlorite, 2% chlorhexidine digluconate or 0.2% peracetic acid to models produced using molds which were not disinfected, with 3 alginate materials (Cavex ColorChange, Hydrogum 5 and Jeltrate Plus). The molds were prepared over matrix containing 20-, 50-, and 75-µm lines, performed under pressure with perforated metal tray. The molds were removed following gelation and either disinfected (using one of the solutions by spraying followed by storage in closed jars for 15 min) or not disinfected. The samples were divided into 12 groups (n=5). Molds were filled with dental gypsum Durone IV and 1 h after the start of the stone mixing the models were separated from the tray. Surface detail reproduction and dimensional accuracy were evaluated using optical microscopy on the 50-µm line with 25 mm in length, in accordance with the ISO 1563 standard. The dimensional accuracy results (%) were subjected to ANOVA. The 50 µm-line was completely reproduced by all alginate impression materials regardless of the disinfection procedure. There was no statistically significant difference in the mean values of dimensional accuracy in combinations between disinfectant procedure and alginate impression material (p=0.2130) or for independent factors. The disinfectant solutions and alginate materials used in this study are no factors of choice regarding the surface detail reproduction and dimensional accuracy of stone models.

Este estudo comparou a reprodução de detalhes da superfície e alteração dimensional de modelos de gesso obtidos a partir de moldes desinfetados com hipoclorito de sódio 2%, digluconato de clorexidina 2%, ou ácido peracético 0,2% a modelos confeccionados utilizando moldes que não foram desinfetados com três alginatos (Cavex ColorChange, Hydrogum 5, Jeltrate Plus). Os moldes foram preparados sobre matriz contendo linhas de 20, 50 e 75 µm realizado sob pressão com moldeira de metal perfurada. Os moldes foram removidos após a geleificação e desinfetados (utilizando uma das soluções por pulverização, armazenados em frascos fechados durante 15 min) ou não desinfetados. Assim, as amostras foram divididas em 12 grupos (n=5). Os moldes foram preenchidos com gesso dental Durone IV e uma hora após a manipulação do gesso os modelos foram separados da moldeira. A reprodução de detalhes da superfície e a precisão dimensional foram avaliadas usando microscopia óptica na linha 50 µm com 25 mm de comprimento, de acordo com a norma ISO 1563. Os resultados de precisão dimensional (%) foram submetidos à ANOVA. A linha de 50 µm foi completamente reproduzida por todos os alginatos, independentemente do processo de desinfecção. Não houve diferença estatisticamente significativa nos valores médios de precisão dimensional nas combinações entre procedimento de desinfecção e alginato (p=0,2130), ou para fatores independentes. Soluções desinfetantes e alginatos utilizados neste estudo não são fatores de escolha em relação à reprodução de detalhes da superfície e alteração dimensional de modelos de gesso.

Effect of a cordless retraction paste material on implant surfaces: an in vitro study

Cordless retraction paste material for gingival retraction in implant dentistry has recently become of interest to the clinician. However, few studies have been conducted on the use of retraction pastes and their possible interaction with implant surfaces. This in vitro study evaluated the effect of a cordless retraction paste material, Expasyl® (Acteon), on TiUnite® (Nobel Biocare) implant surfaces. Three areas of the fixtures were evaluated before and after contact with the retraction paste using scanning electron microscopy to evaluate changes in surface topography and energy-dispersive spectroscopy to identify any surface chemistry modifications. Alteration of the initial surface after exposure to Expasyl® was identified, with the implant collar showing the most changes.

Dimensional accuracy and detail reproduction of two hydrophilic vinyl polysiloxane impression materials tested under different conditions.

Background and Objectives: A limitation of vinyl polysiloxane (VPS) impression materials is hydrophobicity, and manufacturers have added surfactants and labeled these new products as "hydrophilic." The purpose of this investigation was to evaluate and compare the dimensional accuracy and surface detail reproduction of two hydrophilic VPS impression materials under dry, moist, and wet conditions. Materials and Methods: Ten impressions were made under dry, moist, and wet conditions respectively, with monophase, and regular body VPS impression material using a stainless steel metal die similar to that described in American Dental Association (ADA) specification 19, with lines scribed on it. Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression to the same line on the metal die, by using a measuring microscope. The surface detail was evaluated. A one-way analysis of variance and Student t-test were used to compare mean dimensional changes (α = 0.05). Results: Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of either material. The mean dimensional changes were 0.00084% (+0.00041%) for monophase and 0.00119% (+0.00033%) for regular body. Monophase material was satisfactory in detail reproduction 100% of the time in dry conditions, 90% in moist, and only 20% in wet conditions. The regular body showed 100% satisfactory impressions in dry, 80% in moist, and 10% in wet conditions. With the additional smooth surface evaluation, only under dry conditions impressions with clinically acceptable surface quality were produced. Conclusions: Dimensional changes for both materials were well within ADA standards of minimal shrinkage value of 0.5%.

Efficacy of various spray disinfectants on irreversible hydrocolloid impression materials: An in vitro study.

Background: Most of the materials (casts, impressions, etc.) that are sent to the dental laboratories show the presence of numerous pathogenic microorganisms. All the spray disinfectants are not equally effective against these microorganisms. Aims and Objectives: The aim was to compare the effectiveness of different spray disinfectants on irreversible hydrocolloid impressions and to find out the most effective dilution, contact time, and effect against each microorganism studied. Materials and Methods: The effects of four spray disinfectants, 5.25% sodium hypochlorite, 0.525% sodium hypochlorite, 1:213 (1 part in 213 parts of water) povidone iodine, and 2% glutaraldehyde along with control (distilled water) on irreversible hydrocolloid impressions contaminated with Staphylococcus aureus, Bacillus subtilis and Streptococcus viridans were studied. Results: Sodium hypochlorite, 5.25%, showed 1-min exposure time which was able to effect a 4log10 reduction in bacterial counts against S. aureus and S. viridans followed by 0.525% sodium hypochlorite and 2% glutaraldehyde for 10 min. None were able to effect a 4 log10 reduction against B. subtilis. Conclusion: Sodium hypochlorite with a concentration of 5.25% was the most effective disinfectant and required the shortest contact time (1 min). Not all ADA-approved concentrations of surface disinfectants work equally well on irreversible hydrocolloid impression materials.

Restoration of posterior teeth using occlusal matrix technique.

This article describes a technique for duplicating occlusal surface anatomy using the Biteperf device. Duplication requires an intact occlusal enamel surface and is only indicated when caries lesions are hidden. The occlusal matrix technique allows for preservation of all anatomic details. When the last layer of composite has been placed, the occlusal matrix is forced into the uncured composite to replicate the original occlusal surface, instead of performing manual curing and shaping as in the standard approach. It is technically possible to achieve this effect with any material that is able to copy anatomic details. The main benefits of the occlusal matrix technique, more precisely the Biteperf, are the technical ease of use due to its simplicity and its high accuracy in reconstructing occlusal morphology.

Linear dimensional changes in plaster die models using different elastomeric materials

Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F) were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05) and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm), mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm), polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm) and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm). All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

Prosthetic rehabilitation of patients with microstomia.

Microstomia is defined as an abnormally small oral orifice which can be due to various factors. Microstomia is a definite prosthodontic hindrance to carry out the different treatment successfully. To rehabilitate a patient with microstomia, successfully, the methods and designs incorporated in the prosthesis have to be modified. In the past, various techniques have been tried, incorporating certain biological and scientific methods to rehabilitate patients with microstomia. This article reviews the previously described treatment modalities in case of patients with microstomia.

A comparative study of inter-abutment distance of dies made from full arch dual-arch impression trays with those made from full arch stock trays: An in vitro study.

Objectives: The dual-arch impression technique is convenient in that it makes the required maxillary and mandibular impressions, as well as the inter-occlusal record in one procedure. The accuracy of inter-abutment distance in dies fabricated from dual-arch impression technique remains in question because there is little information available in the literature. Materials and Methods: This study was conducted to evaluate the accuracy of inter-abutment distance in dies obtained from full arch dual-arch trays with those obtained from full arch stock metal trays. Results and Conclusion: The metal dual-arch trays showed better accuracy followed by the plastic dual-arch and stock dentulous trays, respectively, though statistically insignificant. The pouring sequence did not have any effect on the inter-abutment distance statistically, though pouring the non-working side of the dual-arch impression first showed better accuracy.