PubMed · 3296170
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C P Marinello. 1987. [The altered cast method. Casting in prosthodontics].. https://pubmed.ncbi.nlm.nih.gov/3296170/
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To accomplish computerized 3D morphological analyses of maxillary and mandibular casts with malocclusions on the same co-ordinate system, a new reference co-ordinate located on soft tissue has been proposed consisting of the top of maxillary bilateral tubercles and incisive papilla on the maxillary cast. To test the validity of this co-ordinate system, the angles of the occlusal plane in this system were examined on 10 subjects with normal occlusion. In addition, to analyse maxillary and mandibular casts on the same co-ordinate system, a bite block was made under the intercuspal position. The maxillary cast was measured by 3D measuring system, then, the bite block was placed on maxillary casts, and measured similarly. To examine the position reproducibility of this method, 3D co-ordinates of the apex of the buccal cusp of the mandibular pre-molar in five bite blocks were determined. The angles formed of the occlusal plane were 1.3 +/- 1.3 degrees and 0.2 +/- 1.1 degrees on the sagittal and frontal base plane, respectively. This co-ordinate system had enough stability to replace the occlusal plane. By the measurement of bite blocks, the co-ordinates of the mandibular cusp tips were determined within the deviation of 0.2 mm.
STATEMENT OF PROBLEM: Although internal porosity is a potential risk factor for clasp fracture, little is known about its frequency in the clasps of titanium removable partial dentures. PURPOSE: This study investigated the influence of the direction of auxiliary sprues on porosity in the circumferential clasps of a pressure-cast titanium removable partial denture. MATERIAL AND METHODS: Wax patterns of a removable partial denture framework were made on 10 identical refractory casts of a Kennedy class II, modification 1, mandibular partially edentulous arch. For the auxiliary sprues directed to the circumferential clasps, 2 designs were used: straight and curved. Casting was performed in a 1-chamber pressure casting machine. Pore number and size were assessed on radiographs of the castings. The data were analyzed with the 2-tailed Student t test (P <.05). Randomly selected specimens were sectioned for morphologic observation of the internal surface of the pores. RESULTS: The number of pores >or=0.5 mm diameter and the total number of pores were significantly lower in the molar lingual arms of the curved sprue group than in the corresponding clasp arms of the straight sprue group (P =.03 and P =.009, respectively). No significant differences between the 2 groups were found for pores of any size in other locations. The pores had smooth internal surfaces. CONCLUSION: Within the limitations of this study, the curved sprue design produced significantly less porosity in the circumferential clasp arms of a cast titanium removable partial denture than the conventional straight design. The results suggest that internal porosity in titanium castings can be controlled through sprue design.
This article presents a technique for the fabrication and incorporation of a stable and fireproof identification plate into a cast partial denture framework. Embossing tape is embedded in the wax pattern of the major connector. The resulting casting reproduces the embossed lettering, which is identifiable through the tissue-colored acrylic denture base resin.