Single complete denture part 1 Dr.Mohammed Al sayed 11/3/2008

Definition: A single complete denture is a complete denture that occludes against some or all of the natural teeth, a fixed restoration, or a previously constructed removable partial denture or a complete denture.

*Construction and delivery of single complete dentures is more complicated than the delivery of upper and lower complete dentures on a patient.

There are four reasons for this increased difficulty: 1.The ability of the patient to generate heavy occlusal forces, due to the existence of opposing natural teeth. 2.The unsuitability of the denture foundation tissues (mucosa) to resist high occlusal forces from the opposing natural teeth, which results in advanced bone loss of the residual alveolar ridges. 3.Supraeruption of the opposing natural teeth produces an unharmonious occlusal plane, and minimizes the vertical space for setting the opposing denture teeth. 4.Mesial drifting of the opposing natural teeth results in an increased mesial axial angulation (tilting) which produce an unharmonious occlusal plane

The dentist may be able to overcome the problems associated with the single complete denture By Applying the following: a. All fundamental steps in denture construction must be followed and completed to perfection( without minor errors). b.The occlusal plane of the natural teeth in the opposing arch must be made harmonious.

Maximizing the ability of the denture supporting tissue to withstand destructive occlusal forces: 1.The denture base borders should have the maximum extension within the functional anatomical limits. In this way the forces of occlusion will be distributed over the largest possible area of the denture supporting tissue.

Causes of occlusal problems and fracture of denture bases: 1.Occlusal stress on the maxillary denture and the underlying edentulous tissues from the opposing natural dentition. 2.The position of the mandibular teeth, which may not be probably aligned to achieve bilateral balance for stability. 3.Flexure of the denture base.

Single complete denture may be opposed by one of the following: 1.Natural teeth. 2.Fixed restorations 3.A removable partial denture. 4.An existing complete denture.

1.Single complete denture opposed by natural teeth: The most common complete denture is a complete upper denture and lower natural teeth. In evaluating the natural dentition the following should be checked: 1.Uneven alignment of teeth. Example: Tipping and extrusion 2.Character of the occlusal surface. Natural teeth often exhibit varying steepness of the cusps and/or associated abrasion and wear.

3.Cross-bite relationship. 4.Number and position of the natural teeth. The stability of the single upper denture during function is directly proportional to the number of posterior with which it occludes.

Complicating factors for the single mandibular complete denture opposing natural teeth: 1.The denture supporting tissues for the mandibular complete denture is relatively small when compared to the maxillary supporting tissue. 2.The mucosa and submucosa overlying the periostium and bone of the lower residual ridge is thin. 3.For the above two reasons, the underlying bone is extremely prone to resorption from occlusal forces of the natural teeth. 4.Solution: consider extraction the healthy upper teeth, since the long term health of the mouth is at stake.

There are two situations When a mandibular complete denture, opposing upper natural teeth are accepted: 1.When the patient has a class III jaw relationship. This occur when the mandible is larger than normal or the maxilla is smaller than normal. 2.When the patient has a cleft palate, either with the cleft partially open or closed.

Difficulties found with maxillomandibular jaw relations for the single maxillary denture: A. The finalized maxillary wax occlusal rim may not be parallel to the ala - tragus line, since the opposing occlusal surfaces of the mandibular natural teeth will dictate the angulation of the occlusal plane. b. The labiolingual thickness of the anterior wax occlusal rim will interfere with establishing the correct vertical dimension of occlusion, if the future anterior teeth arrangement will require vertical overlap. (fig. A) c. Occlusal rim occlusion: The anterior-lingual portion of the maxillary anterior wax rim must be made thin, in order to allow the lower incisors to produce the correct vertical overlap for establishing the correct vertical dimension of occlusion, which will be less than the vertical dimension of rest. (fig. B)

Occlusal modification requirements for the opposing mandibular natural /restored teeth: 1.Assess the occlusal plane. One method is to use an occlusal template, in order to assess the relation of the occlusal surfaces of the teeth to the occlusal template. 2.The occlusal surfaces of the natural teeth can be ground or restored to give a more suitable occlusal plane. 3.Grossly malpositioned teeth can be considered for extraction or for orthodontic repositioning. 4.Occlusal modification are best experimentally performed upon mounted diagnostic casts in order to determine the feasibility of occlusal grinding or for restorations.

Occlusal adjustment-Perfecting the plane of occlusion: Two methods: 1st method: a. Mount the maxillary edentulous cast and the mandibular cast on a semi-adjustable articulator using an arbitrary facebow and a centric relation record at the established vertical dimension of occlusion. b. Make a protrusive record and set the horizontal condylar guidance ( condyle angle). c.Set the upper artificial teeth one by one on the denture base and adjust the lower occluding stone teeth (by scraping) in order to establish a harmonious occlusal plane. Mark the area of the stone teeth that have been altered.

d. When a favorable occlusal plane and articulation of the teeth have been achieved, the occlusal adjustment are then carried out on the natural teeth in the mouth using the marked diagnostic cast and the trial denture set up as guides. e. After the occlusal adjustment have been made in the mouth ,a new impression of the natural teeth is obtained, a new centric relation record is made, and the new lower cast is mounted on the semi- adjustable articulator. f. The maxillary artificial teeth are rearranged for harmony in centric relation occlusion and in extrusive movement. The next clinical step is the try in of the trial wax up maxillary complete denture.

2nd method: a. Use an occlusal metal template. The inferior surface of the template is slightly convex. The ideal occlusal plane is established when all the incisal edge and occlusal cusps touch this metal occlusal plane resulting in a slightly occlusal plane of the mandibular teeth. b. The metal template is placed on the incisal and occlusal surfaces of the lower stone cast teeth. Cusps and incisal edges which are too high or too law are identified.

c. The high stone cusps are reduced with sharp knife until there is an even contact of all teeth to the curved occlusal plane template. Reduced areas on the stone teeth are marked on the cast by pencil. d. The occlusal adjustment are then carried out on the natural teeth in the mouth, using the pencil marked diagnostic cast as a guide.

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