A removable partial denture using an esthetically designed round-rest distal clasp on maxillary anterior abutment teeth: a clinical report

Color changes of polyetheretherketone (PEEK) and polyoxymethelene (POM) denture resins on single and combined staining/cleansing action by CIELab and CIEDE2000 formulas

PURPOSE

The purpose of study was to investigate the long-term effect of staining and/or cleansing solutions on the color stability of two non-metal removable partial denture materials.

METHODS

One hundred disks (25×3mm) of polyoxymethylene (POM) and polyetheretherketone (PEEK) were immersed in water, wine, coffee, cleanser and combo bath, simulating normal daily use. Color parameters in the CIELAB system was measured every 30 cycles up to 240 using a contact colorimeter and color differences estimated using ΔE_ab and ΔE₀₀ formulas. Two-way repeated measures ANOVAs and regression analyses were performed at α=0.05.

RESULTS

Regression analysis indicated a strong R² between color changes and number of cycles, for both materials. Tests of within-subjects effects for the ΔE_ab revealed significant differences among cycles and between the materials in the wine and coffee baths (p<0.001). Significant materialXcycles interactions were also recorded with all staining baths. ΔE₀₀ values were lower than ΔE_ab up to 63.6%. Tests within and between-subjects effects for the ΔE₀₀ gave similar but not the same with ΔE_ab results.

CONCLUSIONS

ΔE₀₀ found to correlate well with ΔE_ab. Long term exposure of both materials showed a progressive discoloration in all except control baths. POM discolored more than PEEK in coffee, and combo baths but not in cleanser. Discoloration was smaller in combo bath (where a cleanser was also used) indicating the effectiveness of a cleanser to prevent long term discoloration of both materials.

Ring Rest Seat Design for Severely Tilted Molar Abutment Tooth: An Alternative Option

A ring rest was used for a buccally inclined distal third molar, which served as an abutment for a distal extension Kennedy class II removable partial denture (RPD). This report describes in detail the ring rest design, which offers a conservative treatment option while complying with RPD principles. The design also allowed use of existing occlusal contact on the maxillary third molar without resulting in an overcontoured clasp design. Preparation technique for the rest, along with rationale for selection and design, is discussed. The need for other adjunctive treatment options was also avoided by using the inclination of the maxillary third molar, thereby providing a conservative, cost-effective, and time-efficient alternative treatment.

Esthetic Management of Unilateral Cross Bite with Dento-vestibular Enhancement Prosthetic Appliance

Unilateral crossbite is a commonly encountered condition in clinical practice. The most frequently employed treatment protocol to manage unilateral crossbite is orthodontic correction or orthognathic surgery or combination of both. When the clinical situation less favours both these modalities of management, a transitional prosthetic appliance--dentovestibular enhancement prosthetic appliance- can be effectively used to manage this condition.