Factors that augment the role of direct retainers in mandibular distal-extension removable partial dentures

Several features of RPD design that augment direct retainer design were identified. They are as follows: 1. The duplication of direct retainer function by other prosthesis components 2. Physiologic adjustment of the framework to assure contacts with abutment teeth that are consistent with the design and intended functions of the components and that transfer stress in a manner those teeth are designed to accept 3. Intimate adaptation of denture bases to the residual mucosa, with recall visits to monitor this adaptation 4. Specific loading of the denture bases through selective placement of artificial teeth 5. Splinting of abutment teeth     

In vitro deformation of acetyl resin and metal alloy removable partial denture direct retainers

STATEMENT OF THE PROBLEM: Acetyl resin removable partial denture (RPD) direct retainers may provide an esthetic alternative to conventional metal direct retainers. The effect of repeated stress on acetyl resin direct retainers is unknown. PURPOSE: This study compared deformation of acetyl resin and metal alloy RPD direct retainers after repeated dislodgments over a test die. MATERIAL AND METHODS: Ten acetyl resin (Thermoflex) and 10 metal alloy (Ticonium Premium 100) RPD direct retainers, fabricated to manufacturers' specifications, were dislodged over a stainless steel die by means of a laboratory test apparatus for a simulated 3-year period (5000 cycles). Occlusal and facial digital images made before and after cycling were measured (mm) for direct retainer deformation by using computer-imaging software (Scion Image 1.62). Student t tests (alpha=.05) were performed for statistical comparisons. RESULTS: A significant difference in deformation between acetyl resin and metal alloy direct retainers occurred in the occlusal view (P=.045), but not in the facial view (P=.832). Average deformation varied but was greatest in the occlusal view: 0.09 +/- 0.8 mm for acetyl resin direct retainers compared with 0.01 +/- 0.9 mm for metal alloy direct retainers. Average facial view deformations revealed no significant differences: 0.039 +/- 0.6 mm for metal alloy and 0.033 +/- 0.7 mm for acetyl resin direct retainers. CONCLUSION: Within the limitations of this in vitro study, significantly greater deformation resulted with acetyl resin compared with metal alloy direct retainers after 3 years of simulated use.     

Acrylic resin blockout for interim removable partial dentures.

A technique using autopolymerizing acrylic resin as a blockout material has been described. This technique greatly simplifies the laboratory construction and insertion phases of the complex interim removable partial denture. It is not suggested that the acrylic blockout replace the wax blockout if a heat-cured denture base is not indicated. Wax should be used if a "sprinkle-on" autopolymerizing acrylic resin is used for the denture base.     

Hinged mandibular removable complete denture for post-mandibulectomy patients.

The presence of excessive lingual undercuts after mandibulectomy and surgical reconstruction is a rare clinical condition and presents unique prosthodontic challenges. The goals of prosthodontic treatment include: providing lip support, improving articulation, reducing drooling, and regaining favorable esthetics. This article describes the fabrication of a hinged removable mandibular complete denture prosthesis using a sectional impression tray technique and a custom-made hinge mechanism. Clinical and laboratory procedures of the prosthetic treatment are described, and the advantages and disadvantages are reviewed.     

Margin fit of metal crowns and bridge retainers

The margin fit of metal crowns and bridge retainers was examined radiographically in individuals who were registered to receive treatment at the School of Dentistry, University of Bergen. One sample consisted of 184 individuals registered in 1967-68 and another one of 232 individuals registered in 1982-83. In all, 2057 proximal surfaces could be examined. The margin fit was scored as excess, deficit, or satisfactory. In the 1967-68 single-crown sample margin excess was recorded for 66%, margin deficit for 8%, and satisfactory fit for 26%, on the average. In the 1982-83 single-crown sample margin excess was recorded for 36%, margin deficit for 5%, and satisfactory fit for 59%. In the 1967-68 sample bridge retainer margins on the average scored 60% excess, 10% deficit, and 30% satisfactory fit. In the 1982-83 bridge retainer sample margin excess amounted to 33%, margin deficit to 4%, and satisfactory fit to 63%. The possible reasons for the differences between the two samples are discussed.     

Clinical characteristics affecting the need for relining of class 1 and class 2 removable mandibular prostheses]

This study attempts to identify, from a sample of people wearing a class 1 or 2 removable prosthetic device on the lower jaw, the extent of the relining needs for these prostheses and their determining factors. Epidemiological methods were used to solve this problem. The relining needs increase with the amount of time elapsed since the prosthetic device was put in the mouth (p = 0.014). As for the other factors reviewed, i.e. class of device, type of retainers used, and occlusion, the authors have identified trends instead of real risk factors, since the impact of this study was significantly reduced due to the small number of people we were able to recruit. It was not always possible, therefore, to verify the statistical meaning of the associations observed. In clinical practice, the treatment plan should include a periodical evaluation of the relining needs. As it is now impossible to establish the approximate time when a prosthetic device may need relining, patients wearing one should be examined periodically and regularly.     

Maxillary segmental osteotomies for mandibular removable partial denture patients.

The posterior maxillary osteotomy is a versatile and useful treatment alternative for a variety of dentofacial conditions. Its place in the management of bilateral distal-extension removable partial denture construction has been described along with a report of treatment of a patient.