Complete Denture Introduction
The scientific and technological basis of dentistry is expanding rapidly in the world where alternative changes in the management and financing of health care have raised the public expectations of better “quality of life”.
- Dentistry has come a long way from just replacing missing teeth to replacing lost alveolus supporting facial structures, recreating esthetics, reestablishing phonetics, and many other major developments.
- Most of all we can say that in prosthetics by using all the artificial materials as well as technologies we can give a natural appearance to an individual at its best. Improvements in material science form just one aspect of complete denture prosthodontics.
- These are driven by the change in theoretical concepts, perceptions of dentists, and a need to fulfill the above.
Read And Learn More: Complete Dentures Question and Answers
Advancements in complete denture prosthodontics can be classified into two broad categories.
- Advancements in theoretical concepts
- Advancements in material science.
The history of dentistry is strewn with examples of new materials or techniques developed for entirely different purposes triggering a revolution in the way things were done in an entirely different field.
Similarly, the need for specific purposes in one field has accelerated the field of research in a different field. For example, the need for accurate replication of the terminal hinge axis and jaw positions in relation to the base of the cranium has spurred an interest in biomechanical engineering thereby combining the two entirely different fields of science. Necessity has indeed proved to be the mother of invention.
Recent Advancements In Theoretical Concepts
Theoretical concepts form the basis of perfection in several instances since a concept has to be developed prior to its application in a patient. There have been numerous advancements in theoretical concepts pertaining to different stages in complete denture fabrication.
These can be enumerated as follows:
- Advancements in diagnostic aids
- Advancements in impression procedures
- Advancements in jaw relation records
- Esthetic guides
- Advancements in fabrication techniques
- Miscellaneous
Advancements In Diagnostic Aids
- The graph analysis method for evaluating complete denture patient psychology is a relatively new concept for predicting the prognosis.1 It is proved that Graphoanalysis in addition to properly structured interviews and questionnaires is useful in the evaluation of the behavior of an individual, especially for recognizing difficult patients.
- A new classification of the psychology of complete denture patients has been proposed, which provides a theoretical approach, a step-by-step guide to clinicians to better understand the thoughts, aspirations, and expectations of complete denture patients and their effects and consequences in different patients, when not met with.
- This approach attempts to overcome the disadvantages of House classification of patient psychology which simplifies the behavior of patients into just 4 categories.
- Recent advances in computer-aided design/computer-aided manufacturing (CAD/CAM) technology, medical imaging, and rapid prototyping have added to the armamentarium of implant dentistry in terms of efficiency, accuracy, and predictability. Rapid prototyping and CAD/ CAM technology are used to fabricate stereolithographic surgical templates for flapless implant placement.
- A photogrammetric technique for analysis of jaw positioning and hidden surfaces attitude analysis is proposed recently. It uses the original photogrammetric system for noncontact 3D measurements and surface 3D reconstruction. Two techniques are proposed for jaws’ 3D models’ mutual arrangement according to their original position in a mouth.
- The first one is point-based and it allows for determining jaw displacement concerning a set of reference points. The second technique is surface-based and it uses a scan of teeth occlusion for jaw positioning. Both methods provide adequate accuracy for dentistry. It is of huge diagnostic value in complete dentures.
Advancements In Impression Procedures
Apart from the basic principles of complete denture impression making which were introduced in the middle of the nineteenth century as listed below, many changes happened in the concept of impression.
- Concepts of atmospheric pressure.
- Maximum extension of denture bearing area.
- Equal distribution of pressure.
- Adaptation of denture-bearing tissues.
To this were added the principles of retention, stability, comfort, biocompatibility, accuracy, etc. Some of the new techniques added to the already existing techniques for complete denture impressions in the last 10 years is the Management of flabby tissue Flabby tissues are common clinical finding that poses no problem of pain and discomfort but adversely affect the support, retention, and stability of complete dentures.
- Several techniques have been proposed as nonsurgical alternatives to such cases focusing on a modified impression technique to record the flabby tissue in its undisplaced form.
- For example, technique 1 describes the custom tray to be made in two parts, the first part of which contains a “lattice-work”, which strengthens the tray followed by a second tray, which adequately supports the final impression. A standard neutral zone technique was additionally employed for the mandibular ridge as it was severely resorbed.
- lynch et al 2 describe the use of polyvinyl siloxane material that is used very commonly in dental practice in a judicial manner, instead of using complicated techniques and materials to manage flabby ridges.
- Onur et al 7 describe a modified impression procedure and a method of fabricating a 2-piece collapsible denture for a patient with limited oral opening as a result of the resection of a precancerous lesion on the maxillary lip.
- Fabricating the denture in 2 pieces (a smaller anterior piece and a larger, hinged, collapsible posterior piece) enabled the patient to place and remove the denture.
- In 2005, a modified functional impression technique described by Alexander et al used a removable functional acrylic resin handle that was attached to custom impression trays allowing an excellent peripheral sealing zone got by patient-conducted muscular and jaw motion.8 In 2008, Dr.
- Joseph Massad described an impression technique that involves the layering method of impression-making that maintains the integrity between layers of the impression
- Materials of varying viscosities control the path of insertion, thus minimizing the incidence of overextension.9 digital impression systems In the case of digital impressions, the creators of the impression-taking devices have introduced scientific developments in the fields of optics, digitization, and CAD/CAM into the art of capturing impressions of prepared teeth and surrounding structures to develop 3D digital and even physical representations from which dental restorations can be made.
- They include the CAD/CAM products CEREC® (Sirona Dental Systems,www.sirona.com) and E4D Dentist (D4D Technologies, www.d4dtech.com) and the dedicated impression products Cadent iTero™ (Cadent, www.cadent.com) and Lava™ Chairside Oral Scanner C.O.S. (3M ESPE, www.3mespe.com).10
Advancements In Jaw Relation Aids
- Historically, a number of techniques have been suggested for registering interarch relationships during complete denture therapy. A graphic recording method dating to the turn of the 20th century, but recently updated, involves the use of a central bearing device.
- This device can aid the practitioner in the clinical achievement and registration of both horizontal and vertical jaw relationships and is particularly useful when muscle deprogramming of habitual mandibular closure is indicated.11 Use of this central bearing device has been shown to be very precise.
- The concept has recently enjoyed a resurgence of interest due in part to newly developed instrumentation (Massad Jaw Recorder System, Global Dental Impression Trays, Inc., www.gdit.us).
- Advantages of this new central-bearing device include ease of attachment to record bases using conventional light-activated laboratory resin and a unique pivoting central bearing pin for adjustment in all dimensions during the recording process.
- This new central-bearing device comes complete with all of the elements necessary to assist in the registration of centric relation in various clinical situations, including edentulism, partial edentulism, full edentulism, small-arch diameter, and large-arch diameter.
- Kavo arcus facebook: A fully functional 3-dimensional computerized pantographic registration system to capture both, static and dynamic occlusal records for articulator programming and diagnostic set-ups. Accuracy and repeatability are unsurpassed with all records permanently archived.
- A virtual articulator is another new concept. The virtual articulator can simulate the specific masticatory movement of the patient. During mandibular animation, the program calculates the sites where the opposing teeth come into contact.
- The studies made to assess the reliability of the virtual articulator show good correspondence in the visualization of the number and position of the dynamic contacts. A virtual articulator is a precise tool for the full analysis of occlusion in a real patient.
- 12 Complete denture occlusion simulation system (CDOSS) in the field of dental restoration is another new aid that is a useful tool to deal with the functional aspects of occlusal morphology in a diagnostical and therapeutical sense. With the aid of this software, the visualization and diagnosis of mandibular movement can be easily realized.
- Centric relation – a new concept: A new concept of Centric Relation is defined as “A clinically determined position of the mandible in which both condyles are in their anterior and uppermost position in their glenoid fossae.
- This definition differs from the old definition in that the centric relation is the relationship of the mandible to the maxilla when the condyles are at the most posterior portion of the glenoid fossa.
- Because some authors believe that in Centric Relation all the load of the mandibular residual ridge is transferred to the joint cavity pushing the head of the condyle against the avascular disc and the cavity wall.
- Recently it has been found that there is evidence of nerve and blood vessels in this posterior aspect which can get compressed causing pain to the individuals.
- But such pains are not noted in the patient thereby suspecting the actual position of this condylar head in the joint cavity. So recently authors have suggested their position to be the anterior uppermost position of the joint cavity.
Advancements In Esthetic Concepts
- Denture esthetics has essentially involved a subjective approach, employing long-standing techniques and principles to help reach a satisfactory esthetic and functional outcome for the patient and dental team. Particularly, this is the case with the clinical arrangement of the teeth in the trial-denture base.
- There have been no significant advances in recent years as far as concepts are concerned, however, such principles have been well-described by a few authors.13
Advancements In Fabrication Techniques
Use of CAD/CAM System for Fabrication of Complete Dentures
- The development of computer-aided systems for designing and fabrication of Complete Denture is a relatively recent development.
- So far the use of CAD/CAM has primarily been focused on field restoration such as inlays crowns because of difficulty in recording soft tissue morphologies of edentulous areas, and interocclusal relationships.
- Methods of recording and measuring 3D morphology have been greatly improved with the recent advancement of optoelectronic measuring unit CAD software.
Procedure
Involves three major steps
- Impression procedure
- Denture designing
- Denture fabrication.
Impression procedure
- As the first step, an impression of the load-bearing area of the residual ridge and denture borders was made for the maxillary and mandibular arches using a specially designed double impression tray with Conventional Rubber Base or Silicone Impression Material.
- Maxillary and mandibular impressions are held at specific vertical heights and horizontal relation in the patient’s mouth.
- The double impression trays are transferred and mounted on a 3D laser scanner that has a rod around which both the impression can rotate to full 360°.
- Two-dimensional images are recorded by spread laser beam and Four Charged-Couple device cameras while the impression is made to move nearly. Surface images are obtained at three different angles time required – 15 to 20 mins.
Denture Design, Arrangement Of Artificial Teeth
Denture space data are transferred to an engineering workstation. Artificial teeth and denture surface data from the database are overlapped and matched with those of the denture space. The placement of artificial teeth is done to achieve proper stress distribution.
Denture Fabrication
- Either a numerically controlled milling machine or a 3-D laser lithography machine can be used. Laser lithography creates 3D models of new products based on CAD design. Therefore, only two outer shells (occlusal/polished part and tissue surface part) are photopolymerized.
- Tooth shade acrylic resin composites are used to fill inside the occlusal portion and two surfaces are connected using a reference point. Tissue-colored auto-polymerizing resin composite is then placed into the space and excess is removed, and shells are polished using a conventional manner.
Orofacial prosthesis design and fabrication using stereolithography:15 The use of stereolithography for the manufacture of implantable prostheses is a relatively new aspect in dentistry.
- Until now, its use with regard to mandibular resection has been to produce preoperative models that allow more sophisticated planning of the contour and better preparation of the metallic framework to be implanted.
- The framework rejoins the mandible restoring its function. Data extracted from Computed Tomography (CT) scans can be used to produce computer models of three-dimensional (3D) anatomical structures.
- Using stereolithography, a rapid prototyping technique these computer models can be made into solid physical models.
- The surface and internal structure of the anatomical site can be reproduced by polymerization of UV light-sensitive liquid resin using a laser beam. The laser rays progressively polymerize photo monomers on the surface of the vat solution.
- The model is built vertically step by step as the polymerized section submerged beneath the surface of the solution. These models are then used for the diagnosis and treatment planning of various cases.
Miscellaneous Concepts
- The effect of low-energy laser application in the treatment of denture-induced mucosal lesion 16 has recently gained considerable attention. They are primarily used to relieve pain, reduce inflammation and edema and accelerate healing.
- Studies on the biological effects of low-energy lasers have been concerned with the ability of such light to increase blood circulation within regenerated tissues increase the production of collagen by fibroblast and promote a suppressive effect on the immune system. Furthermore, increased mitotic activity has been reported, which indicates that growth stimulation occurs.
- Recently, the bactericidal effect of light from a low-energy laser was introduced as an alternative approach to Antibiotics and Antiseptics in eliminating cariogenic and periodontopathogenic bacteria from lesions.
- The greatest benefit of using a low-energy laser is that its effects can be achieved without damaging host tissues and with protection to the operator. The effect of therapeutic laser treatment on both soft tissues and bone with subsequent improvement of denture foundation after treatment of denture-induced mucosal lesions.
Recent Advances in materials
- Vinyl-polyether Hybrids: The newest class of impression material is the vinyl-polyether hybrids that include SENN. This new class of impression material combines properties from the addition of silicone and polyether impression materials.
- SENN is supplied as a 2-paste auto mixing system and contains a polymer with polyether and siloxane (Example: addition silicone) groups that will combine elements and benefits of both impression materials.
- With the polyether groups, a hydrophilic material is provided without the use of a surfactant. With the siloxane groups on the polymer chain, a material that is dimensionally stable and recovers from deformation is combined with polyether properties.
- The material has a platinum catalyst, and the setting reaction is contaminated when powdered gloves are used to mix the material. EXA’lence is another new generation of Vinyl PolyEther Silicone (VPES) impression material.
- EXA’lence is said to combine the advantages of both polyether and vinyl-polysiloxane silicone impression materials, resulting in excellent hydrophilicity, flow, dimensional accuracy, and high tear strength.
- Silginat is an addition-curing, elastomeric polyvinyl siloxane (PVS) impression material to be used as an alginate alternative in a variety of anatomic impressions. Silginat boasts many advantages over alginate impression materials for both the practitioner and the patient.
- It was designed with a low-tear resistance to avoid inadvertently dislodging restorations or orthodontic appliances while providing excellent palatal definition and detail. Silginat has an optimized medium flow viscosity (medium-body viscosity per ISO standards) with heavy body hardness when set.
- Silginat is also highly thixotropic and flows properly under pressure, giving it ideal workability. The thixotropic nature of the material also helps prevent patient gagging. Artex Rotofi Facebook: This is a new addition to the arsenal for successful prosthodontists.
- The Artex Facebow comes complete with a 3-D universal joint, nose bar/nasion, pair of standard balls, set of 10 disposable bite forks with thermoplastic bite compound, tray handle, and metal before.
- Single lever eliminates torque distortion often found in face bows that require screws. The Artex opens symmetrically, which means alignment without side shift or alteration of the sagittal distance.
- A simplified clinometer has been designed with the intention of reducing the cost of the commercially available Hanau clinometer.17 This clinometer can be fitted to the conventional three-point articulator and used by undergraduate dental students to learn teeth arrangement in an esthetic manner.
- A biofunctional prosthetic system and Premium Swiss Precision Dentures are the recent additions to the existing systems of denture fabrication. They include the utilization of high-end dental products like layered teeth, high-strength flowable resins, nanometers, and intraoral tracing devices.
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