Prosthetic Dentures
Background
Should the removable partial denture be considered an outdated therapeutic measure, or is it still a reasonable option? Great strides have been made in the realm of surgical and implant techniques, and it is foreseeable in the future that many cases of tooth loss will be rehabilitated with fixed prostheses. Although this limits the indications for a removable partial denture, that device should not be relegated to the category of outdated therapeutic treatments. Indeed, the contraindications to the installation of implants, whether medical, anatomical or financial, are the very indications for removable partial dentures. For this reason, removable partial prosthetic rehabilitation still remains valid today.
Therapeutic approach
The removable partial denture is a real treatment, in the sense that when it is introduced into a disrupted oral environment, it restores and maintains equilibrium. Its objectives are twofold:
1. Directly: To replace lost teeth.
2. Indirectly: To preserve the equilibrium of the remaining teeth, bones and mucous membranes, as well as the temporomandibular joint.
In other words, the goal is to improve and restore aesthetic appearance, help support mastication and ensure that the remaining teeth stay in place.
Achieving these objectives involves every discipline of dentistry. Each step is important and should never be overlooked, since each represents an essential component for prosthetic integration and durability, including the preservation and integrity of the tissues. Often, the remaining teeth require restorative dentistry, endodontics, periodontics or even a fixed prosthesis, before a removable partial denture can even be considered. It is also not uncommon for pre-prosthetic surgery to be considered on the soft tissues (such as a labial or buccal frenum interfering with the luting or path of prosthetic elements) or the hard tissues (such as residual roots that are palpable beneath the mucous membrane).
Mouth examination
A well-documented diagnosis in anticipation of the development of a treatment plan, following a decision approved by the patient, would be impossible without first obtaining the patient’s medical status and performing a thorough mouth examination. For this, the dentist must consider the state of the patient’s alveolar bone health as well as the condition of individual ridges, mucous membranes and occlusion, as well as the existing restorations in the mouth. The dentist must thoroughly and systematically observe the entire oral cavity. Visual and digital observations of the teeth, bone, gums and underlying mucous membranes must be performed. A complementary X-ray will enable the dentist to better evaluate the quality of the bone tissue, namely the level of bone around the teeth. Study models are necessary to round out this examination.
Oral preparation for the removable partial denture
Study models will enable the dentist to better visualize the span of the edentulous areas as well as the migration of teeth (tipping, rotation or twisting) on each arch. This analysis helps to uncover any correctable prematurity as well as any elements that may interfere with the future partial denture. Since the prosthetic value of the remaining teeth is an important factor in the prosthetic decision—especially the teeth that will support the “clasps”—in some cases, certain teeth will need to be stabilized through individual dental restoration. This can involve anything from single or compound fillings to fixed pivot-crown restorations. Finally, the preliminary phases include the modification of the tooth through preparation of the dental supports on the occlusal surface of the teeth where the metal framework will rest. These also include the drafting of plans to determine the ideal angle of insertion for the prosthetic device.
Design and manufacture of the partial denture
Any removable partial denture puts unusual pressure on the teeth and supporting structures since it forces them to perform additional tasks. Each component of a removable partial denture must play its part in the distribution of the forces and stress on the support structures. Indeed, it is the metal framework that plays the biggest role. For that purpose, it consists primarily of the following:
• The large connector: The part of the frame that connects all components of the prosthesis. Whether upper or lower, any removable partial denture must possess a rigid structure that connects the elements located on one side of the arch to those on the other side.
• Supports: Rigid extensions of the metal frame that are placed on the remaining teeth, which have been prepared to receive them, in order to distribute the weight and help provide vertical support for the prosthesis.
• Clasps: Anchoring devices made of metal that surround the teeth for support to keep the prosthesis in place.
Once the framework has been cast and is perfectly fitted to the teeth, which have been prepared to receive it, artificial teeth are added to it to fill in the edentulous spaces. The respective roles of the patient and dentist do not end once the prosthesis has been inserted in the mouth, as maintenance procedures play a crucial role in ensuring prosthetic balance, which is indispensable to the durability of the prosthesis and the remaining dental components.