Dental Materials for Complete Dentures PDF

Dental Materials For Complete Denture Dr. Malak Bamigdad BDS KAU, Saudi Board in Prosthodontic dentistry  6th Edition By Arthur O.Rahn, J R. Ivanhoe, K D. Plummer  Outlines Denture Base Materials Denture Teeth Denture Liners Denture Tissue Conditioners De...

Dental Materials For Complete Denture Dr. Malak Bamigdad BDS KAU, Saudi Board in Prosthodontic dentistry  6th Edition By Arthur O.Rahn, J R. Ivanhoe, K D. Plummer  Outlines Denture Base Materials Denture Teeth Denture Liners Denture Tissue Conditioners Denture Repair  Knowledge of the materials used for denture base construction, the principles of their use, and the selection of ancillary products available help the clinician provide the most effective, appropriate treatment for each patient.  Denture Base Materials Denture bases are fabricated of either polymeric materials or metal. The most popular material for denture base construction is a polymer. Polymers are very easily shaped and formed, and have a less weight than the metallic materials. The purpose of the denture base: 1. cover the existing residual ridge 2. provide facial contour 3. hold the artificial denture teeth in the correct position 4. provide an intimate contact with the underlying mucosa without interfering with movements of the cheeks and tongue Loss of Facial support (Sunken Appearance) Polymethyl Methacrylate (PMMA)  Methods of Polymerizing denture base resin 1. Heat Polymerization 2. Chemical reaction (Autopolymraized) 3. Microwave Energy 4. Light activation Resin-Based Dentures (Heat-Polymerized Materials)  VIP What are the stages in Acrylic polymerization? Which stage the acrylic is ready to work with it?  Why dentures must be kept wet?  Resin shrinkage during polymerization (approximately 0.3 to 0.5%) Dimensions of the denture are slightly smaller Denture will absorb water from its storage fluid, and expand slightly (0.1 to 0.2%), making its final dimensions almost exactly the same as those of the mouth. Auto-Polymerized Materials Microwave Cured Acrylic Resin Light Cured Resin  Metal-Based Dentures The side of the denture that will be next to the oral mucosa (the tissue- bearing side) will be metal, and a polymer material will be added to stimulate gingiva and hold the denture teeth in place.  Advantages of the metallic base: 1. more accurate fit 2. transfers heat from foods and fluids to the palatal area 3. For the mandibular denture, this weight helps to keep the denture in place, metal-based maxillary dentures, the added weight may compromise the retention of the prosthesis.  Tooth Retention Mechanical undercut (with no chemical bonding) Micromechanical retention  Porcelain Teeth Advantages: hard and wear resistant ( less likely to demonstrate a loss of occlusal vertical dimension ) Disadvantages their hardness, which can be a factor in excessive wear of any natural teeth transmit impact forces from biting to the underlying mucosa, which helps to increase in the rate of bone resorption occurring in the underlying residual ridge fracture with minimal trauma clicking sound difficult to contour to fit ridges and to  Polymer (Plastic) Teeth Advantages: much softer than porcelain less the stresses to the residual ridge less wear resistant ( no wear in opposing teeth ) easily contoured to fit the underlying ridges and are easy to adjust at insertion. less likely to fracture than porcelain teeth, but their occlusal surfaces do wear more rapidly.  Denture Liners ill-fitting denture condition: Over time, the residual bone remaining after tooth extraction continues to slowly resorb resulting in a space between the tissue-bearing side of the denture and the residual ridge. The clinician has two choices: 1. New Denture 2. Denture Reline ( chairside or laboratory )  The decision depends on the amount of ridge loss and resulting space. If the space is large and occlusal vertical dimension has been lost, make new denture. if the space is relatively small, a thin layer of new plastic can be added to the existing denture base. Chairside Reline Materials Either a hard or a soft material Two types: 1. powder and liquid that, when mixed, is very similar in content to that used when making the autopolymerizing denture base material 2. a single cartridge that is placed into a delivery gun (Both hard and soft reline materials are available using this type of delivery system.)  Laboratory Reline Materials For the lab-processed relines, the old denture surface is roughened as before, an impression material is placed directly on the denture base, and the denture is inserted into the patient’s mouth 1st type: new denture base material is added and polymerized directly against the old base under heat and pressure. Advantages: much stronger, bonded more to the denture, and is more resistant to fluid absorption and color change  2nd type: soft, silicone-based reline material advantage : staying flexible for considerably longer periods than those made totally of a modified methacrylate- based polymer. Disadvantages: silicone surface is fairly porous and, over time, tends to accumulate bacteria and fungi; it must be treated to reduce this potential.  Denture Tissue Conditioners Temporary denture liner that provides a cushioning to absorb loads to the underlying residual ridge, and allows those tissues to heal during function. Indications: irritated and inflamed tissues Why tissue conditioners must be frequently replaced ???? It may become hardened, resulting in recreation of the irritated state of the residual ridge seen prior to treatment loss of resiliency is the result of dissolution (leaching) of a component (plasticizer) that helps to keep the material flexible Denture Replacement of a lost tooth or rejoining Repair pieces of a fractured denture base (or both) by using an autopolymerizing resin.  Create locks or undercuts (liquid+ acrylic) This technique will produce a more dense, stronger polymer. The transverse strength of heat-polymerized repairs is approximately 80% of the unbroken material, whereas it is only 60% of the original strength for the chemically polymerized product. Impression Materials Alginate Hydrocolloid (an irreversible hydrocolloid) Acceleration of Alginate setting  Break the seal around the impression and exerting a rapid, snapping motion. Disinfecting Alginate impression Polyvinyl Siloxane (PVS) and Polyether elastomeric impression material is often used for making final impressions PVS available in a range of viscosities: light-bodied (a more fluid-like material) medium-bodied, heavy-bodied (much thicker consistency) a putty (very dough-like and nonfluid). The viscosity to be used is based on the consistency of the tissues the more unsupported and movable the tissue, the more fluid (the lighter bodied) the impression material desired to minimize distortion of the movable tissues.  For disinfection, the PVS material may be soaked in any type of disinfectant for any length of time, because it does not absorb water (is hydrophobic). Polyethers absorb water (are hydrophilic), so they must be spray disinfected, and placed in a plastic bag (like alginate disinfection technique). No need to pour impression immediately.  Dental Stones the different types of stones vary in hardness, strength, surface detail reproducibility, and setting expansion. maximal properties of these gypsum products, the proportioning of water and powder as well as the method of mixing  special motor-driven mixing devices are available ( vacuum spatulation). All types of dental stones release heat (are exothermic) during curing.  Types of Stones Type I (impression plaster ): very soft, weak Type II (model plaster, mounting stone): have the highest setting expansion, weaker than Types III and IV materials. Type III stone (dental stone) is less strong that Type IV, expands slightly more ,used to fabricate master, a relatively high strength, costs less Type IV: very hard, strong, wear-resistant, and low expansion high-strength stone Interocclusal Registration Materials Registration Materials: moldable thermoplastic material or a polyvinyl siloxane Dental Waxes Baseplate wax :available in three different levels of hardness, with different flowability at specific temperatures (room temperature, body temperature, and an elevated temperature). Type 1 wax is used mostly in denture base construction sticky wax: low-melting impression Wax used to help capture sections of oral mucosa in a nonfunctional state. In the warm, fluid state, this material can be painted over the impression tray to capture delicate, distortable tissues Denture Cleansers Denture cleansers can be divided into two groups: abrasives and solutions Abrasive Cleansers: special formulations of paste-based cleansers with soft-bristled brushes are recommended Solution Cleaners: Hypochlorites Ozygenating Agents Mild Acids  Hypochlorites: Sodium hypochlorite is a well-known antibacterial agent, and in mild concentration, can be used to remove adherent protein from the denture surface as well as kill organisms present highly corrosive to the metal framework of removable partial dentures loss of color and a general whitening. Oxygenating Agents Solutions :of oxygenating agents (such as peroxides, perborates, and percarbonates) are made by dissolving tablets or powders containing these dentures are immersed for a period.  Oxygenating agents should not be used if the denture base contains a soft liner, as the reaction of this type cleanser tends to irreversibly harden the liner.  Denture Adhesives in the majority of cases, these adhesive materials are not needed if careful attention is given to the details of the entire denture fabrication process. use in emergency situations where immediate denture stabilization is desired Indications: little-to-no remaining residual ridge to help supply resistance to lateral denture movement (stability), for edentulous patients with cleft palates, and for patients who wear post cancer treatment intraoral prostheses  Second, some denture cleaners may allow a mild acid buildup in the saliva and could potentially etch (remove superficial enamel and dentin) the dentition in patients with retained natural teeth  Powder-Based Products: The powdered material is sprinkled over the surface of a wet denture base and is then inserted into the mouth  Paste-Based Products: water-resistant spread until it forms a thin layer Thank You