Edentulous options

March 21, 2012

Effecting more than 40 million patients in the United States alone, edentulism has become a significant problem worldwide and has caused an increase in patients presenting with a broad range of functional and emotional ailments that add to the stress of losing their teeth.1,2

Effecting more than 40 million patients in the United States alone, edentulism has become a significant problem worldwide and has caused an increase in patients presenting with a broad range of functional and emotional ailments that add to the stress of losing their teeth.1,2

Among the most common problems, physical limitations like premature aging and loss of chewing efficiency contribute to emotionally damaging effects like altered self-image, dislike of appearance, and anxiety when discussing their problem with others.2,3

When offered conventional treatments, patients experienced impaired oral function, pain, insufficient retention and instability.2
Historically, removable prosthetics were uncomfortable and only made symptoms worse.4,5 Forced to use their tongue, cheeks and lip muscles, simply keeping their dentures in place was challenging for patients because there was nothing for them to grasp onto.4,5 Limiting functional ability, conventional treatments also have been directly correlated with a loss of bite force.4,5

Studies have shown that after many years of wearing dentures, many edentulous patients experienced a great reduction in bite force, demonstrating only 5.6 psi.4,5 With a bite force this low, even the simplest tasks like eating are very difficult.4SR Phonares® NHC

Composed of a nanohybrid composite material, SR Phonares NHC Denture Teeth are specifically designed to match the age and characteristics of the individual patient, while offering a high degree of durability.7,8 True-to-nature “white esthetics” are now achievable with specially designed interdental closures and unparalleled surface textures.7,8 Further, the tooth moulds present dentists and technicians with unparalleled opportunities to create denture teeth that mimic the surrounding dentition.7 The SR Phonares NHC system also features a unique proximal “Set & Fit” design that allows for easy setup of anterior teeth.7,8

SR Phonares Lingual NHC denture teeth offer the ideal occlusal scheme in cases requiring removable dental prostheses, where positional stability is required (i.e., implant prosthetics).7,8 Comparatively, the SR Phonares Type NHC line of classic denture teeth is suitable for universal application in cases requiring partial, complete, and hybrid denture prosthetics.7,8

Through the use of innovative CAD/CAM technology, ideal symmetry can be created in the anterior region and symmetrical external geometry in the posterior, which allows for true-to-dimension enlargement of the posterior teeth.7,8

SR Ivocap® Injection System

To eliminate the problem of inaccuracies in fit caused by chemical shrinkage of polymethyl methacrylate during polymerization, the SR Ivocap Injection system from Ivoclar Vivadent features an innovative controlled heat and pressure polymerization based system.9 Offering a high degree of polymerization, along with a strong bond to resin teeth, it provides many benefits over materials of the past.9,10 Compensating for acrylic shrinkage, the exact amount of material needed continuously flows into the flask, permitting the fabrication of high-quality dentures that provide an excellent fit and are comfortable to wear.9,10 Additionally, because the material is distributed in capsule form, no mixing or dosing is required.

The SR Ivocap polymerization system reduces the risk of system-induced increases in vertical dimension and spherical deformation, eliminating the need for time consuming occlusal adjustments.9,11 Promoting homogeneity, the risk of fracture is also greatly reduced.9

Combined with excellent handling characteristics and high polishability, the material is easy to work with and maintainable because the surface is resistant to plaque accumulation.9,12

The case study below demonstrates the use of SR Phonares NHC prostheses and SR Ivocap Injection to restore a young edentulous patient’s anterior dentition to full function and natural esthetics, after tooth loss and extraction due to advanced caries.

Case presentation

A 31-year-old female patient presented to the office with an edentulous maxillary arch and remaining mandibular dentition that could not be restored because of caries (Fig. A). After discussing different treatment options with the patient, it was decided that the remaining mandibular teeth would be extracted. A full maxillary and lower full immediate denture would then be fabricated by the prosthodontic resident. Ultimately, the definitive treatment plan included the fabrication of nanohybrid composite dentures (SR Phonares NHC) to replace the previously missing and newly extracted dentition.

Clinical Protocol

01 The carious dentition in the mandibular was removed by the resident prosthodontist.

02 Custom trays were then fabricated from the preliminary casts using light-curable materials, which would be used for the final impressions.

03 A self-curing temporary liner material (Coe-Soft, GC America) was used to create the definitive impressions, which were then beaded, boxed and poured with white dental stone (Figs. B & C).

04 The casts were trimmed and land areas were beveled. A cast analysis was then completed and marks were made on the casts (Fig. D).

05 Following the prescribed 21 mm anterior height, the maxillary esthetic control base, the lower stabilized base, and the occlusal rim were constructed (Fig. E). While constructing the maxillary esthetic control base with the rim former, a 5 mm ridge lip was placed in the hamulus notches of the patient’s cast. 

06 Once complete, the maxillary esthetic control base and the lower occlusal rim were presented to the patient and tried in. The initial vertical dimension of occlusion, vertical dimension at rest, midline, lip position, and incisal position were then determined. A facebow registration and centric relation record were recorded to facilitate proper mounting.

07 Using the hamular notch to create parallelism with the pupillary line, the rim former was used to set the maxillary anterior teeth (Fig. F).

08 Based on their optic qualities, resistance to wear, and through discussions with the patient, SR Phonares NHC teeth were selected in mould S72/L52 and LU5/LL5. A universal soft anterior mould was chosen to maintain a youthful look in shade A1.

09 The maxillary 6 anterior and occlusal rims were tried-in to verify proper phonetics, labial support and midline symmetry. A new vertical and facebow record were taken prior to remounting (Fig. G). 

10 The remaining full complement of teeth were then set and waxed for final try-in (Fig. H). The mandibular teeth were set with anterior/posterior curve and medial lateral curve using a three-dimensional set-up template (Fig. I). The clinician determined to raise tooth Nos. 10 and 11 slightly gingivally.

Laboratory Protocol

01 The case was first sealed on the master casts, followed by investing and boiling-out (Fig. J).

02 Two coats of an innovative separator fluid from Ivoclar Vivadent were placed on warm casts, which were then allowed to cool and dry. 

03 Denture tints (Kayon, Kay-See Dental) in shades F, H and A were applied and allowed to cure for 15–20 minutes (Fig. K). The tints were then moistened with Kayon monomer.

04 A cold-cure monomer (ProBase Cold, Ivoclar Vivadent) was then applied to the ridge lap of the teeth and a small amount of SR Ivocap Injection denture base material in shade US-L was extruded from the capsule. A thin flap of US-L resin was then placed into three quadrants­-one in each of the posterior sections and one in the anterior region-to cover the tints.

05 The flask was closed and placed in the clamping press at 8-bar pressure for a final injection. After the initial 5 minute injection, the cases were then placed in a polymerization bath (Ivo-4 Bath, Ivoclar Vivadent) for 35 minutes at 204–208 degrees. The prostheses were then allowed to cool in a cold water bath for 30 minutes.

06 The processed SR Phonares NHC dentures were remounted, milled and finished for final delivery to the patient (Figs. L & M).

Upon delivery to the office, the dentures were tried-in to test fit and esthetics. After confirming the case, the patient was very pleased with the feel of her new removable prosthetics and the natural appearance of her new smile (Fig. N). The final cases were then slated for implants on the maxillary to preserve her function in the long-term.

Conclusion

Through the use of an innovative nanohybrid composite denture material and an advanced base material, the dentist and technician in this case were able to restore a young patient’s function and esthetics, without the need for highly-invasive treatments like implants. By improving the fit and feel of her removable prostheses, the patient now has a smile that not only appears natural, but one that also gives her comfort and greater confidence.

Although implant retained prostheses and other restorative options have begun to replace removable prostheses as the treatment of choice, the decided treatment should ultimately be determined by what is best for the patient functionally, esthetically and financially.1,2 Advances in material sciences and techniques have vastly improved support, fit, function and esthetics of removable prostheses to provide solutions in even the most challenging cases.1,2