Assessment of surface hardness of acrylic resins submitted to accelerated artificial aging.

AIM: The aim of this study was to assess the influence of accelerated artificial aging (AAA) on the surface hardness of acrylic resins. METHODS: The following three commercial brands of acrylic resins were tested: Vipi Flash (autopolymerized resin), Vipi Wave (microwave heat-polymerized resin) and Vipi Cril (conventional heat-polymerized resin). To perform the tests, 21 test specimens (65x10x3 mm) were made, 7 for each resin. Three surface hardness readings were performed for each test specimen, before and after AAA, and the means were submitted to the following tests: Kolmogorov-Smirnov (P>0.05), Levene Statistic, Two-way ANOVA, Tukey Post Hoc (P<0.05) with the SPSS Statistical Software 17.0. RESULTS: The analysis of the factors showed significant differences in the hardness values (P<0.05). Before aging, the autopolymerized acrylic resin Vipi Flash showed lower hardness values when compared with the heat-polymerized resin Vipi Cril (P=0.001). After aging, the 3 materials showed similar performance when compared among them. The Vipi Cril was the only one affected by AAA and showed lower hardness values after this procedure (Pp=0.003). CONCLUSION: It may be concluded that accelerated artificial aging influenced surface hardness of heat-polymerized acrylic resin Vipi Cril.

Masticatory behavior in individuals with temporomandibular disorders.

BACKGROUND: Masticatory behavior was investigated in a group of patients presenting with temporomandibular disorders (TMDs) and compared with a Control Group. The goal of study was also to assess if patients were capable of making judgements about chewing difficulties and intensity of pain. METHODS: A comprehensive examination protocol was used to gather data about signs and symptoms of temporomandibular disorders. Subjects under study were instructed to chew and images were recorded in a videocassette for further analysis. We used a category scale to evaluate intensity of pain and chewing difficulties in a group of 23 TMD patients and 23 controls independent of age, sex or socioeconomic status. Full dentures wearers were not included in this study. RESULTS: The results of this investigation demonstrated that the frequencies of difficulties to open the mouth wide, unilateral chewing and chewing difficulties were significantly more prevalent in the group of TMD patients as compared to the control. Bruxing behavior was more prevalent in TMD patients and the time to eat a cookie was significantly longer. Subjects were capable of making judgements about severity of pain and chewing difficulties. In the TMD Group, average of both judgements were the same or close when subgroups were divided according to chewing preference and location of pain. CONCLUSIONS: Based on the results of this study, we concluded that the chewing pattern in TMD patients cannot solely be considered as a response to the location of pain and dysfunction.

Arthrogryposis multiplex congenita in a patient with limited mouth opening: a case report.

This report describes a case of arthrogryposis multiplex congenita and concomitant bruxism with limited mouth opening and pain in the temporomandibular joints (TMJ). A conservative treatment with a myorelaxing splint and physiotherapeutic exercises was prescribed resulting in improvement to the muscular and joint conditions and a reduction in pain.

Occlusal splint therapy with a positioning orifice.

The authors studied the effect of a positioning orifice introduced in the anterior palatine region of occlusal splints for patients with craniomandibular disorders of swallowing and speech patterns. The patients were evaluated in four distinct situations. It was concluded that the splint orifice significantly favored swallowing and speech while the splint was being used, and is more comfortable for the patient.

Myofunctional therapy combined with occlusal splint in treatment of temporomandibular joint dysfunction-pain syndrome.

The objective of the present study was to relate changes in reflex-vegetative functions and phonetics to the etiology of temporomandibular joint dysfunction-pain syndrome. Myofunctional therapy associated with an occlusal splint had a very significant effect in relieving the pain and dysfunction caused by this type of disorder.

[Medical rugosity (Ra) of the surface of stone models from alginate impressions using two processes: manual spatulation and vacuum mechanical spatulation]. / Avaliação da rugosidade média (Ra) da superfície de modelos de gessopedra, obtidos de moldes de alginatos manipulados por dois processos: espatulação manual e espatulação mecânica a vácuo.

The differences in superficial smoothness of 108 stone models, obtained from three marks of alginates, manipulated by two different techniques of spatulation (a. manual; and b. mechanic with vibration under vacuum), were studied. The 108 stone models (resultant from the factorial product: 3 alginates x 2 techniques x 6 stones x 3 replica = 108) were analysed by means rugosimeter (Talisurf 10). The results showed that the superficial smoothness of the models was not affected significantly by any of the two techniques tested. The alginate Jeltrate offered the best results, and the group represented by the stones Moldaroc/Gaúcha III/Durastone T/Castone was better than the Vel-Mix, and the Vel-Mix statistically better than the Glastone.

[Comparative study of the capacity of elastomers in reproduction and transmission of details to gypsum models]. / Estudo comparativo da capacidade dos elastômeros na reprodução e transferência de detalhes para os modelos de gesso.

The authors studied the ability of three elastomeric impression materials in reproducing and transmitting three grooves, engraved in the polished surface of a stainless steel model, to gypsum models. The grooves were 17, 21 and 25 micrometers wide, and the fails in reproducing, as well as in transmitting the minor details to gypsum, were also investigated as to the effects of gypsum particle size, proportional relation water/powder and plasticity of the mixture. The three elastomeric impression materials used were a polysulfide, a silicone and a polyether, and the six gypsum products were two improved stones type IV, two dental stones type III and two dental plasters type II. Scores 3, 2 and 1 were attributed respectively to the 17, 21 and 25 micrometers grooves reproduced in the molds, as well to the same grooves transmitted to the gypsum models. The results showed that all the impression materials tested were able to reproduce in the molds all the three grooves present in the steel model. Nevertheless, when gypsum models were examined, it was verified that the grooves so well reproduced in the molds were neither equally nor uniformely registered in the respective models, the best results being achieved by the polysulfide and the silicone, an the worst by polyether, As to the gypsum products, the type II gypsum presented the most unfavorable results.

Importance of periodic control after fitting a total prosthesis--case report.

A patient was seen at the Total Prosthesis Clinic complaining of facial pain after using the same prosthesis for 46 years. Clinical examination revealed TMJ disturbance due to a loss of the vertical dimension caused by a wearing of the teeth. Diagnosis indicated replacement with new prostheses, with a gradual recuperation in the vertical dimension by the application of resin over the lower teeth and a reconditioning of the support tissues. After the alleviation of pain, correction of the dysfunction and reestablishment of the vertical dimension of occlusion, new prostheses were made. At the end of treatment, the patient felt a relaxed facial musculature, lifting the mandible to a resting position instead of constantly maintaining it in occlusion as before. The patient was given instructions as to use, conservation and hygiene of the prostheses and oriented to return for annual evaluation of occlusion and of the supporting oral structures, as well as the stability of the prostheses.