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.

Influence of anatomic reference on the buccal contour of prosthetic crowns

During clinical practice, when performing prosthetic rehabilitation with single crowns, improper reproduction of the dental contour by the dental laboratory is a common occurrence. Therefore, the present study evaluated the fidelity of the reproduction of the buccal contour in an upper left canine performed by three Dental Prosthesis Technicians (DPT) using the indirect laminate veneer technique. First, the DPTs confected the veneers based on a model obtained from the upper arch of a dental dummy, containing a replica of an upper left canine with a prosthetic preparation for a laminate veneer. Then, the same DPTs received other identical models, now with the replica of the upper left canine with no preparation, to be used as an anatomical reference for confecting the laminate veneers. The laminate veneers were then bonded to the plaster models and had their buccal contour individually measured. Measurements were also made of the buccal contour of the reference canine. The data were analyzed by ANOVA and the t-test (p = 0.05). Results showed 100 percent of buccal overcontour when the laminate veneers were compared to the reference canine, regardless of which DPT confected the veneer and regardless of using or not the anatomical reference. The DPTs who participated in the present study were unable to acomplish a faithful anatomical reproduction of the buccal contour, creating an overcontour in all samples. This situation may be responsible for increasing the probability of periodontal and esthetic harm in clinical practice.

Assessment of impressions made for fixed partial denture prosthesis in Jordan

This study was carried out to assess the quality of impressions sent to dental laboratories in Jordan. A sample of 136 impressions and stone casts were examined for technical errors in 35 laboratories that construct fixed partial dentures. They were sorted into these categories: unusable, unsatisfactory, acceptable or satisfactory The type of impression material and tray, opposing arch impressions, and occlusal records were noted. Instructions to technicians were assessed for completeness and clarity. Half of the specimens inspected were categorized as unusable or unsatisfactory. These were found in commercial dental laboratories. They showed at least one clinical error such as drags or indefinite finishing lines in impressions and inadequate reduction, undercuts, or obvious taper on stone casts. Alginate impression material was used of 655 up the cases. Only 27% of specimens were accompanied with instructions. Of these 22% were graded poor. No occlusal records were available with 54% of specimens and no articulators were used except in dental school laboratories. The quality of impressions were unsatisfactory or unusable in 50% of cases. Of the 37 available instructions 8 were not clear

Estudo da lateração dimensional de um silicone polimerizado por reação de condensação / Investigation of the dimensional change of a condensation silicone

O objetivo deste trabalho foi avaliar a influência das características morfológicas da parede axial dos preparos em relaçãoà alteração dimensional de um silicone plimerizado por reação de condensação. Para isso, foi utilizado um modelo padrão em alumínio, co 04 pilares angulados de 7,5mm de altura, 9mm de largura e angulações: 0 graus (p1), 6 graus (P2), 16 graus (P3) e 6 graus com retenção na cervical (P4). A técnica de moldsagem utilizada foi a do material em consistência densa e fluida em dois estágios, com casquetes metálicos para alívio, o que originou espessura padronizada de 2,0mm para moldagem final. Foram obtidos 11 moldews (Silon 2APS, Dentsply), os quais preenchidos por gesso tipo IV (Durone, Dentsply), originaram os corpos-de-prova que, posteriormente, foram mensurados em um projetor de perfil (Jopnes & Lanson-mod.Epic-30E-Springfield, vermont-USA), com ampliação de 10x e resolução da ordem de 0,001mm. Posteriormente, esses valores foram comparados ao modelo padrão, submetidos à análise do intervalo de confiança e teste t student, sob nível de significância de 5%. Obtiveram-s eos seguintes valores para a largura dos corpos-de-prova: p1 (9,143+-0,061); p2 (9,066 +-0,094); p3(8,974+-0,084) e p4 (7,772+-0,311). Verificou-se diferença estatisticamente significante para a largura entre os pilares p1, p2 e p4, sendo que os corpos-de-provaq apresentaram-se mais largos do que o modelo padrão. Porém não houve diferença estatisticamente significante para a latura dos corpos-de-prova. Concluiu-se quwe quanto maior a angulação do preparo, menor a alteração dimensional

Impresión bucodinmica versus impresión tradicional / Bucodynamic versus conventional impression

En el siguiente trabajo se realizó una introducción de los problemas que posee dun paciente desdentado total, también de las características de una prótesis completa. Se explica cómo se produce el movimiento elástico mandibular y cómo puede influir en las prótesis. Además se realiza una comparación entre una técnica tradicional y las ventajas de emplear la técnica bucodinámica. Finalmente se detalla paso por paso la construcción de una prótesis completa superior e inferior con la técnica bucodinámica

Avaliaçäo do reembasamento na moldagem com resina acrílica gelada / Evaluated of cold acrylic resin impression

Avaliou-se o reembasamento de moldes obtidos pela técnica de moldagem com resina acrílica gelada comparativamente à uma técnica convencional de moldagem com casquete preenchido com mercaptana. Foi utilizado um dispositivo metálico contendo um troquel para casquetes e um para moldagem. Os troquéis foram metalizados pela eletrodeposiçäo de íons prata no molde. A alteraçäo dimensional dos moldes foi mensurada em microscópio de profundidade, pela discrepância de alinhamento horizontal entre a borda oclusal de um anel de aço que simula uma coroa total e se adapta perfeitamente ao troquel padräo, e a face oclusal de cada troquel reproduzido. As médias das alteraçöes dimensionais e respectivos desvios-padräo, em micrômetros foram: A-) 678,8 (ñ59,2) para Duralay sem reembasamento, 379,9 (ñ72,9) para Duralay com reembasamento e 18,8 (ñ6,2) para o Permlastic. A resina acrílica sem reembasamento apresentou maior alteraçäo dimensional. Troquéis reproduzidos a partir dos moldes de mercaptana apresentaram-se dimensionalmente mais próximos do padräo. O reembasamento demonstrou proporcionar melhora significante na moldagem com a resina acrílica gelada