David Ross Boyd Professor Emeritus Department of Fixed Prosthodontics University of Oklahoma College of Dentistry. We met at the University of New Mexico at the beginning of her freshman year in 1956.
Preface
An attempt has been made to provide a good working background in the various facets of fixed prosthodontic therapy. The biggest change in the replacement of missing teeth is of course the widespread use of endosseous implants, which make it possible to replace teeth without damaging adjacent healthy teeth.
Acknowledgments
An Introduction to Fixed Prosthodontics
A tooth or implant that serves as an attachment for a fixed partial denture is called an abutment. The pontic is connected to the fixed partial denture retainers, which are extracoronal restorations that are cemented or otherwise attached to the abutment teeth or implants.
Health history
There are numerous conditions of a non-infectious nature that can also be important to the patient's well-being. In addition, effort should be made to obtain an accurate description of the patient's expectations regarding the disease.
TM J and occlusal evaluation
The patient may present with limited opening due to tightness of the masseter, temporalis, and/or medial pterygoid muscles. If the patient touches an area of muscle, other than the TMJ, there is likely a dysfunction of the neuromuscular system.
Intraoral examination
Diagnostic casts
The true inclination of the abutment teeth also becomes apparent; as a result, problems can be expected in a common deployment path. The relationship between the front teeth and the front guide can be seen and analyzed.
F ull-mouth radiographs
The diagnostic wax-up, performed in ivory wax, allows the patient to see all the compromises that will be necessary. Jeske AH, Suchko GD; ADA Council on Scientific Affairs and Division of Science, Journal of the American Dental Association.
Fundamentals of Occlusion
On translation of the mandible to maximum opening, the condyle reengages the disc, clicking into position as it does. As it does, it encounters the eminence of the glenoid fossa and moves downward simultaneously.
Determinants of mandibular movement
The neuromuscular system monitors, through proprioceptive nerve endings in the periodontium, muscles and joints, the position of the lower jaw and its trajectories of movement. When the teeth are not in harmony with the joints and the movements of the lower jaw, there is said to be an interference.
Occlusal interferences
Dentists have indirect control over this determinant through procedures performed on the teeth, which can affect the response of the neuromuscular system. A dysfunctional interference is an occlusal contact between the maxillary and mandibular teeth on the side of the arches opposite to the direction in which the mandible has moved in a lateral excursion (Fig 2-13).
Normal versus pathologic occlusion
In closure, the condyles are in their most superoanterior position against the discs on the posterior slopes of the eminence of the glenoid fossae. During lateral excursions of the lower jaw, the contacts on the working side (preferably on the eyelets) instantly disconnect or separate the non-working teeth.
B ilateral balanced occlusion
It is largely a prosthetic concept that dictates that a maximum number of teeth should make contact in all extrusive positions of the mandible. Due to the multiple tooth contacts that occurred as the mandible moved through the various excursions, there was excessive frictional wear on the teeth.43.
Unilateral balanced occlusion
Bilateral balanced occlusion is based on the work of von Spee40 and Monson.41 It is a concept that is not used as often today as it was in the past. This is especially useful in the construction of a complete denture, where contact with the non-functioning side is important to prevent tipping of the prosthesis.41.
M utually protected occlusion
The anatomical determinants of mandibular movement (i.e., condylar and anterior guidance) strongly influence the occlusal surface morphology of the teeth being restored. It is beyond the scope of this text to discuss all of the nearly 50 lines written on this subject.
M olar disocclusion
There is a relationship between multiple factors, such as immediate lateral translation, condylar inclination, and even disc flexibility, on the cusp height, cusp location, and groove direction that are acceptable in the restoration. Disclusion measurements from the mesiofacial cusp tips of mandibular first molars in asymptomatic test subjects with good occlusions showed an average separation of 0.5 mm in function, 1.0 mm in nonfunctional movement, and 1.1 mm in protrusive movement.54 Therefore, one of the goals of treatment in placement restorations should produce a posterior occlusion with buffer space that equals or exceeds deviations resulting from natural variations found in the TMJ.
Condylar guidance
Anterior guidance
The greater the vertical overlap of the incisors, the longer the posterior cusp height can be. The greater the horizontal overlap of the incisors, the shorter the tip height should be.
Articulators
This is the location of the hinge axis, which is marked with ink on the patient's face. An error of 5.0 mm in the location of the THA will produce a negligible antero-posterior.
Interocclusal Records
The undirected method produces a physiological "muscle position", but it can be difficult to achieve consistent results due to the patient's muscle activity. This allows the muscles to act freely and allows the condyles to move into a physiological position.4,5 The muscles will then rotate the mandible forward and upward.
Armamentarium
While the patient closes with light pressure, strips are added one at a time in the anterior area until the patient no longer feels any posterior tooth contact.
Technique
The registration material should be injected between the teeth on both sides of the arch and allowed to harden (Fig. 4-8). By trimming the tips of the facial cusps, the complete placement of the registration on the maxillary and mandibular cast can be visualized (Fig. 4-14).
Articulation of Casts
F acebow armamentarium
F acebow record technique
The Quick Lock Toggle is inserted into the slot of the bite fork with the head of the thumbscrew facing down, and the screw is tightened (Fig. 5-7). The bite fork is rinsed with running tap water, and the plastic ear pieces the face bow.
M ounting the maxillary cast
The maxillary cast has been mounted on the articulator with the transfer base and transfer assembly removed
M ounting the mandibular cast
The mounting stone must be placed in the undercuts on both the base of the casting and the mounting plate. There should be no stone on the surface of the mounting plate that comes into contact with the articulator frame.
Setting condylar guidance
It is of simple design and can be used either as a direct or indirect mounting device with a removable fork assembly and mounting platform.8 The technique of its use is described. The wing screw on the front of the headbow is loosened and the bite fork assembly is removed.
Custom anterior guidance
To set the mechanical cutting guide, the castings are moved in a. a) The angle of the table is increased to contact the pin. The casts are moved in a right lateral swing, and the left wing of the carving table is raised.
M echanical anterior guidance
The lock nut under the incisal table at the front end of the lower part of the articulator is loosened. The small thumb nut under the left side of the table is loosened and the lift screw is used to raise the left wing of the table into contact with the corner of the guide pin (Fig. 5-75b).
Treatment Planning for Single- Tooth Restorations
This could be a government agency, a branch of the military, an insurance company, and/or the patient. If the patient has to pay, the dentist should give good advice and then let the patient make the choice.
Glass ionomer
When sufficient coronal tooth structure exists to retain and protect a restoration under the expected stresses of mastication, an intracoronal restoration can be applied. Glass ionomer can also be placed quickly enough to serve as an interim treatment to aid in the control of rampant caries (Fig. 6-5).
Composite resin
Glass ionomer has found a place in the restoration of root caries in geriatric and periodontal patients (Fig 6-4). An occlusal approach may be excluded by the presence of an acceptable crown, or a.
Simple amalgam
The extent of tooth preparation for initial lesions has decreased in recent years as the popularity of the concept of "prevention scaling" has waned. However, even minimal preparation for an amalgam restoration significantly weakens the structural integrity of the tooth.9.
Complex amalgam
M etal inlay
Ceramic inlay
M esio-occlusodistal onlay
P artial coverage crown
All-metal crown
M etal-ceramic crown
All-ceramic crown
Ceramic veneer
A survey of 571 fixed prosthodontists, nonspecialist restorative dentists, and dental school faculty predicted a mean survival of 11.2 years for simple amalgams and 6.1 years for complex amalgams.21 A group of 125 complex amalgams was reported to have a survival rate of 76%. at 15 years,20 while another group of 171 complex amalgam restorations showed a 50%. A study of dental school patients that included them reported a 10-year survival rate of 55.9%.14 Another report, based on a general patient population, described a shorter lifespan for composite resin restorations, with 50% of them having failed in 6.1 years.23.
Treatment Planning for the
Replacement of M issing Teeth
In such moments, it is the restorative dentist or prosthodontist who should guide the sequence and referral to other specialists. As a restorative clinician, the restorative dentist is the one to whom the patient will return if they fail; therefore, he must be satisfied with the planned treatment.
Removable partial denture
The requirements for a removable partial denture socket are not as strict as those for a fixed partial denture socket. Periodontally weakened primary abutments may serve better in maintaining a well-formed removable partial denture than in carrying the load of a fixed partial denture.
Conventional tooth-supported fixed partial denture
For successful removable partial denture treatment, the patient must demonstrate acceptable oral hygiene and show signs of being a reliable candidate for retrieval. However, lack of moisture in the mouth will also hinder the success of a removable partial denture.
Resin-bonded tooth-supported fixed partial denture
Although this type of prosthesis is prescribed for periodontal splints, it should be used with extreme caution in those situations. Abutment mobility has been shown to be a serious risk in the successful use of this type of restoration.
Implant-supported fixed partial denture
No prosthetic treatment
If a patient presents with a long-standing edentulous space in which there is little or no drift or elongation of the adjacent or opposing teeth, the question of replacement should be left to the patient's wishes. If the patient does not perceive any functional, occlusal, or aesthetic limitations, prosthesis placement would be a questionable service.
Case presentation
If a tooth adjacent to an edentulous space needs a crown due to tooth damage, the restoration can usually double as a fixed partial denture. Teeth that have been covered with pulp in the preparation process should not be used as fixed partial denture abutments unless endodontically treated.
Crown-root ratio
If several abutments in an arch require crowns, there is a strong argument for choosing a fixed partial denture rather than a removable partial denture. Even then, some compensation must be made for the coronal tooth structure that has been lost.
