The Development Of A Mouth Temperature Thermoplastic Wax And Evaluation Of Its Clinical Application

In the soft palate defect reconstruction with an obturator,an impression material that is always plastic but non-flowing in the oral cavity is needed in order to acquire a functional(such as swallowing and pronouncing)impression of the defective cavity,for the particularity of the anatomy and function of the defect region.General impression materials such as alginate, polyvinyl siloxane,polyether and polysulfide rubber are incapable of acquiring a functional impression, because they are of high solidity and hypernomic fluidity in the mouth. There exists a similar product- KORECTA WAX, but which is still a little hard in oral temperature. Therefore, the purpose of this study is to develop new mouth temperature thermoplastic wax(hereinafter referred to as the oral temperature wax) with independent intellectual property rights, it should have good biological safety, be soft and plastic at oral temperature but does not flow, and be hard and stable in morphology at room temperature.This research includes four experiments:1.Preparation and screening of oral temperature waxThe components A, B, C, D, E ware added to the mixing kettle, being heatedto100 and stirred thermostatically for 1 hour under the protection of nitrogen, and then ℃the mixture was putted into a filtration tank, went through vacuum filtering, impurity removing, discharge and forming,finally the oral temperature wax was get. Compared with KORECTA WAX, texture, ductility, softening point, hardness, curing time and size stability test of oral temperature wax were observed. Repeat adjustment of composition, the physical performance test above.After repeated adjustment formula, oral temperature wax was ready. the proportion of each component is: paraffin wax 49%, mixed crystalline wax 28%, microcrystal wax 12%, rosin 8%, acrylic acid 3%. It can preliminarily meet the requirements for oral temperature wax.2.Physical performance testsBy comparison with the international general KORECTA WAX and Japanese COMPOUND border moulding wax for mechanical properties, the results are as follows: for the oral temperature wax, KORECTA WAX and border moulding wax, softening point was as follows:(52.7±1.0)℃,(60.0±0.8)℃,(67.0±0.9)℃;hardness at 37℃ respectively was:(15 + 4) HA,(25 + 2) HA,(65 + 2) HA, while at 23℃ was:(15±4)HA,(25±2)HA,(65±2)HA; curing time after turning to 23 ℃ from 37 ℃ for oral temperature wax and KORECTA WAX was(11.67 + 0.05) min and(17 + 0.09) min,and there was no statistically significant difference between the two kinds of materials in size stability, stating oral temperature wax could basically meet the requirements of the of impression material in physical properties.3. biological safety testAccording to test methods and requirements regulated by YY/T0268-2008 biological evaluation of medical devices used in dentistry, the newly developed oral temperature wax was tested for the following biological safety test.(1) cytotoxicity test(CCK8 method) was carried out according to the provisions of GB/T16886.5-2003: experimental results show that the cell toxicity grading of oral temperature wax were grade 0 or grade 1, stating that oral temperature wax has no toxicity reaction on the cells;(2) the provisions of GB/T16886.10-2003 mucosa irritation test: test results show that, the mucosal irritation of mouth temperature wax and the negative test materials are in keeping with the control group, with the average score of 0;(3) delayed type hypersensitivity test was carried out using method in GB/T16886.10-2003: the experimental results show that the allergic reaction score system evaluation of oral temperature wax was grade 0,stating no sensitization.4.Clinical application and evaluation of the effect.In 11 cases of patients with soft palate defects, impressions of the defect cavity were made respectively by mouth temperature wax,KORECTA WAX and alginate, which was then used to fabricate an obturator. As both obturators were adapted for one month,for the groups wearing obturator made from wax impression(group A) and from alginate impression(group B), from KORECTA WAX(group D)and group C without obturator,subjective perception for the nose leakage,speech intelligibility(SI) and vowel spectral analysis were measured and analyzed by one-way ANOVA. Clinical results show that: Compared to group B and C,the perceptual ratings of nose leakage,SI values and F1,F2 of [i],F2 of [u],F2 of [ü] were all significantly higher in group A and B.(P< 0.05); there was no significant difference in the perceptual ratings of nose leakage,SI values and the first three formant frequencies of the six simple vowels between group A and D. So we can come to the conclusion, The obturator,which was made from the impression acquired with the temperature molding wax,as well as KORECTA WAX can obviously improve the situation of nose leakage and speech disorder relative to the velopharyngeal incompetent.