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1

Development of removable partial dentures by using additive manufacture and casting processes

Batalha A. E. F., Araújo R. M.

Archives of Materials Science and Engineering

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2017

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Vol. 87, nr 1

33--40

EN

Purpose: This work aims to present a methodology developed for dimensional analysis of removable partial dentures, following a route with a model manufactured by additive manufacture and a further casting process of a Co-Cr alloy part. Design/methodology/approach: The method for designing and manufacturing removable partial dentures (RPD) is focused on their completely virtual design. They are manufactured with resin additive manufacturing chrome-cobalt cast alloys. A 3D image correlation scanner was used for dimensional and geometrical tolerance analysis. Findings: The prostheses manufactured by CAD-CAM route are more accurate than conventional ones, but they suffer distortion during the casting process. This distortion did not interfere with the patient's well-being or with the adaptation to the prosthesis. Research limitations/implications: The technique presented herein paper allows preparing better fitting prosthesis. Providing the best comfort and masticatory power. Practical implications: Improving the precision in the manufacturing process of a removable partial denture is very important for professional dentists and their patients. Originality/value: The proposed technique and the work approach provide the prosthesis preparation with shorter ambulatory time in addition to greater comfort to the patient.

2

Chewing efficiency and occlusal forces in PMMA, acetal and polyamide removable partial denture wearers

Macura-Karbownik A., Chladek G., Żmudzki J., Kasperski J.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 1

137--144

EN

Purpose: Thermoplastic materials, such as acetal (AC) and polyamide (PA), constitute an alternative to polymethyl methacrylate (PMMA) based resins as the materials for removable partial dentures. However, none of the previous studies compared chewing efficiency and occlusal forces in the wearers of dentures made of various materials. Therefore, the aim of this study was to determine and compare the chewing efficiency and occlusal forces in PMMA, PA and AC RPDs’ wearers. The hypothesis was that the type of denture base material shows a significant effect on chewing efficiency (expressed as a degree of food fragmentation) and occlusal force. Methods: The experiment included the group of 30 patients using removable partial dentures. The dentures made of PMMA, acetal and polyamide were tested in each patient. Each denture was worn for 90 days, with a random sequence of the denture manufacturing and insertion. After 7, 30 and 90 days of each denture wear, chewing efficiency coefficient was determined with the aid of a sieving method, and occlusal force was measured with a dynamometer. Results: The use of dentures made of PMMA or acetal was reflected by a marked increase in chewing efficiency and occlusal force. None of these parameters changed significantly with the time of denture wear. Moreover, no significant correlation was found between chewing efficiency and occlusal forces. Conclusions: Denture base material exerts significant effects on the degree of food fragmentation and the level of occlusal forces. The use of dentures and clasps made of materials with lower modulus of elasticity is associated with lower chewing efficiency and lower occlusal forces.

3

The analysis of the effect of wrought wire clasps on the conditions of abutment teeth

Kasperski J, Chladek G., Płonka Ł.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 1

27--33

EN

Laboratory evaluation of spring constants (k) of wrought wire clasps (WWC) separated from removable partial denture (RPD) and the results of tibological tests which represent the dependence of enamel wear with normal force have been presented in the paper. The results of laboratory examinations have been combined with the results of clinical assessment of the level of abutment teeth wear. On the basis of the examinations performed it has been revealed that the following factors have the greatest impact on tribological wear of abutment teeth: the time of using RPD and the normal force exerted by WWC on abutment tooth. Normal force depends to a great extent on the place of contact of WWC with the tooth. It has also been found that abutment teeth featuring higher scale of wear are more loosened. The diameter of wire used for making WWC, total length of the arm and k determined for the total length of the arm did not have any impact upon the scale of wear of abutment teeth.

4

Biomechanical behavior of restored and unrestored mandible with shortened dental arch under vertical loading condition

Tanasić I., Tihaček-Šojić L., Milić-Lemić A.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 4

31-36

EN

The aim of this in vitro study was to investigate the strain distribution of the compressed mandible bone under the applied restoration-removable partial denture and to compare with the same but unrestored mandible under vertical (occlusal) load and to find out whether removable partial denture-restored or unrestored mandible causes greater strain effect on supporting tissue. Four mandible models were tested during loading for the purpose of strain measuring. Digital image correlation system (GOM - German Optical Measuring, Braunschweig, Germany), used for measuring strain consists of two digital cameras and software ARAMIS (6.2.0, Braunschweig, Germany). Remaining teeth suffer from greater strain in the mandible model without removable partial denture (7.5-10%). On the contrary, mandible with removable partial denture shows the maximum strain below the denture saddle (3.5%). However, it can be noticed that the marginal bone of the second lower praemolar in both experimental models is deformed whether the mandible model has (2.8%) or has not (10%) replacement. Within the limitations of this study the higher strain is observed in mandible model without replacement and the strain is limited locally, in the bone region that surrounds remaining teeth and mental foramen.