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Seminar on

DIAGNOSTIC SETUP FOR

REMOVABLE PARTIAL DENTURE

Presented by

Dr. P.S.PRABUP.G.Student

Dept.of ProsthodonticsRagas Dental College & Hospital

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Introduction.HistoryOral examinationVisual examination.Radiographic examinationOral prophylaxis.Exploration.Vitality tests.Diagnostic cast.Cast analysis.On articulator.On surveyor. Interpretation of data.Summary.

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Introduction

• When an RPD ceases to function as intended by the dentist or as expected by the patient. It is generally considered to be in a stage of failure. Most failures result from a deficiency in design or from alterations of the supporting tissues during or after fabrication of the prosthesis. The causes of failure can be categorized under inadequate diagnosis and treatment planning, inadequate mouth preparation.

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Unfortunately, too many RPDs are designed without the use of a dental surveyor. Without question, the dental surveyor is an essential instrument that aids the dentist in making an accurate diagnosis. Surveying identifies those areas of the mouth that need to be modified to accommodate the design of a prosthesis that will promote and maintain oral health.

Inadequate Diagnosis :

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Inadequate mouth preparation

• A second kind of failure results when the dentist does not provide for adequate tooth support by the proper positioning and contouring of the clasp (direct retainer) or for proper tissue support by tissue-conditioning methods and corrected impressions. Also included in this category is the failure of the dentist to create occlusal harmony of the remaining natural dentition before mouth preparation for the RPD.

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History

• Patient interview, during which the dentist should establish rapport with the patient, gain insight in the psychological make-up of the patient, explore any physical problems that may affect the treatment and ascertain the patient’s expectations of treatment.

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Establishing a rapport.

• De Van 1961 stated it when he said we should meet the mind of the patient before we meet the mouth of the patient.

• The patients attitude and opinion relative to dentistry can greatly influence the success or the failure of the treatment.

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Psychological make-up:

• In 1950 Dr. M M House classified patients into Philosophical Histerical Exacting Indifferent

• The patients attitude and psychological make up have considerable influence on the success of the treatment.

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Physical problems on Rx:

• Any positive response in the health questionnaire must be explored and evaluated.

• Systemic disturbances that can have a significant effect on treatment of the patient include the following…..

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Diabetes:

• Uncontrolled diabetes is frequently accompanied by multiple small oral abscesses and poor tissue tone and often has a reduced salivary output.

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Arthritis:

• If arthritic changes occur in the TMJ, the making of jaw relation records can be difficult and changes in the occlusion may occur.

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Paget’s disease:

• May have enlargement of the maxillary tuberosities, which can cause changes in the fit and the occlusion of the prosthesis.

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Acromegaly:

• Patients with acromegaly may have enlargement of the mandible.

• They should be observed frequently to evaluate the fit and occlusion of the prosthesis.

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Parkinson’s disease:

• Characterized by the rhythmic contractions of the musculature, including muscles of mastication.

• The symptoms are some times so severe that it is impossible for the patient to insert and remove the RPD.

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Pemphigus vulgaris:

• Is a disease that usually begins by the formation of bullae in the oral cavity with gradually spreading to the skin.

• In the acute phase a painful oral cavity and dryness of the mouth are common symptoms.

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Epilepsy:

• A grand mall seizure may result in fracture and aspiration of the prosthesis and possibly the loss of additional teeth.

• The construstion of RPD is usually contraindicated if the patient has frequent severe seizure with little or no warning.

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C V S disease:

• Patients with the following require medical consultation before any dental procedure……

• Acute or recent MI• Unstable or recent onset of Angina

pectoris, Congestive Heart Failure, Uncontrolled Arrhythmia, uncontrolled hypertension.

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Transmissible diseases:

• Hepatitis• Tuberculosis• Influenza • And other transmissible disease pose a

particular hazard for the dentist, patient, dental auxiliaries.

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Effect of drugs on treatment

• Increase in age usually means an increase in…………………………

• The need for some type of prosthodontic treatment.

• The use of prescribed and over the countered dugs

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Diagnosis – The determination of the nature of the disease.

ORAL EXAMINATION

A complete oral examination should precede any mouth rehabilitation procedures.

An oral examination should be complete, not limited to only one arch.

It should include a visual and digital examination of the teeth and surrounding tissues with mouth mirror, explorer, periodontal probe, a complete intraoral radiographic survey, vitality tests of critical teeth and an examination of casts correctly oriented on an adjustable articulator and on a surveyor.

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Sequence of oral examination: An oral examination should be accomplished in the following sequence.

1. VISUAL EXAMINATION

Visual examination will reveal many of the signs of dental disease.

Consideration of caries susceptibility is of primary importance.

The number of restored teeth present, signs of recurrent caries, and evidence of decalcification should be noted.

At the time of the initial examination, periodontal disease, gingival inflammation, the degree of gingival recession, and mucogingival relationships should be observed.

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A complete periodontal charting that includes pocket depths, assessment of attachment levels, furcations, mucogingival problems, and tooth mobility should be performed.

The extent of periodontal destruction must be determined with both appropriate radiographs and by use of the periodontal probe.

The number of teeth remaining, the location of the edentulous areas, and the quality of the residual ridge will have a definite bearing on the proportionate amount of support that the partial denture will receive from the teeth and the edentulous ridges.

Tissue contours may appear to present a well-formed edentulous residual ridge.

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Palpation often indicates that supporting bone has been resorbed and has been replaced by displaceable, fibrous connective tissue.

Such a situation is common in maxillary tuberosity regions. The removable partial denture cannot be supported adequately by tissues that are easily displaced.

The presence of tori or other bony exostoses must be detected and an evaluation of their presence in relation to framework design must be made.

During the examination, not only must each arch be considered separately, but also its occlusal relationship with the opposing such.

A situation that looks simple when the teeth are apart may be complicated when the teeth are in occlusion.

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Complete intraoral radiographic survey

The objective of a radiographic examination are

(1) to locate areas of infection and other pathosis that may be present;

(2) to reveal the presence of root fragments, foreign objects, bone spicules, and irregular ridge formations;

(3) to reveal the presence and extent of caries and the relation of carious lesions to the pulp;

(4) to permit evaluation of existing restorations as to evidence of recurrent caries, marginal leakage, and overhanging gingival margins;

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(5) to reveal the presence of root-canal fillings and to permit their evaluation as to future prognosis

(6) to permit an evaluation of periodontal conditions present and to establish the need and possibilities for treatment; and

(7) to evaluate the alveolar support of abutment teeth, their number, the supporting length and morphology of their roots, the relative amount of alveolar bone loss suffered through pathogenic processes, and the amount of alveolar support remaining.

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A thorough and complete oral prophylaxis

An adequate examination can be accomplished best with the teeth free of accumulated calculus and debris.

Also, accurate diagnostic casts of the dental arches can be obtained only if the teeth are clean;

The exploration of teeth and investing structures

These can be explored by instrumentation and visual means. This should include a determination of tooth mobility and an examination of occlusal relationships.

At this time the presence of tori and other bony protuberances should be noted and their clinical significance evaluated.

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Vitality tests of remaining teeth

Vitality tests should be given particularly to teeth to be used as abutments and those having deep restorations or deep carious lesions.

Determination of height of the floor of the mouth to locate inferior borders of lingual mandibular major connectors.

Mouth preparation procedures are influenced by a choice of major connectors.

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DIAGNOSITC CASTS

A diagnostic cast should be an accurate reproduction of the teeth and adjacent tissues.

In a partially edentulous arch this must include the edentulous spaces, since these also must be evaluated in determining the type of denture base to be used and the extent of available denture supporting area.

Purpose of diagnostic casts

Diagnostic casts serve several purposes as an aid to diagnosis and treatment planning.

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1) Diagnostic casts are used to supplement the oral examination by permitting a view of the occlusion from the lingual, as well as from the buccal, aspect.

Analysis of the existing occlusion is made possible when opposing casts are occluded, as well as a study of the possibilities for improvement either by occlusal adjustment, occlusal reconstruction, or both.

The degree of over closure the amount of interocclusal space available, and the possibilities of interference to the location of rests may be determined.

2) Diagnostic casts are used to permit a topographic survey of the dental arch that is to be restored by means of removal partial denture.

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The cast of the arch in question may be surveyed individually with a cast surveyor to determine the parallelism or lack of parallelism of tooth surfaces involved and to establish their influence on the design of the partial denture.

The principal consideration in studying the parallelism of tooth and tissue surfaces of each dental arch is to determine the need for mouth preparation:

(a) proximal tooth surfaces, which can be made parallel to serve as guiding planes, (b) retentive and non-retentive areas of the abutment teeth, (c) areas of interference to placement and removal.

From such a survey a path of placement may be selected that will satisfy requirements for parallelism and retention to the best mechanical, functional, and esthetic advantage.

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3. Diagnostic casts are used to permit a logical and comprehensive presentation to the patient of present and future restorative needs, as well as of the hazards of future neglect. Occluded and individual diagnostic casts can be used to point out to the patient

(a) evidence of tooth migration and the existing results of such migration.

(b) Effects of further tooth migration

(c) Loss of occlusal support and its consequences

(d) Hazards of traumatic occlusal contacts and

(e) Cariogenic and periodontal implications of further neglect.

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4. Individual impression trays may be fabricated on the diagnostic cats, or the diagnostic cast may be used in selecting and fitting a stock impression tray for the final impression.

5. Diagnostic casts may be used a constant reference as the work progresses.

Penciled marks indicating the type of restorations, the areas of tooth surfaces to be modified, the location of rests, the design of the partial denture framework, as well as the path of placement and removal, all may be recorded on the diagnostic cast for future reference.

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CAST ANALYSIS - ON THE ARTICULATOR

A study of the casts on the articulator reveals relationships between opposing teeth and between edentulous ridges that could not be determined by any other methods.

OCCLUSION

The relationship of the teeth of one arch with those of the other arch can be closely observed.

The presence of tipped, rotated, and extruded teeth can be noted, and the problems in design of the prosthesis that they create can be assessed.

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OCCLUSAL PLANE

The status of the occlusal plane is critical in assessing the prognosis for a prosthesis, and it may exert a pivotal influence on the type of prosthesis that should be prescribed.

A plane that undulates because of tipped and extruded teeth will make it very difficult to develop a harmonious occlusion.

Because a harmonious occlusion is crucial to the success of a removable partial denture, the occlusal plane that deviates markedly form normal must be viewed with consideration.

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INTERRIDGE SPACE

The amount of space between the edentulus ridges of the maxilla and the mandible should be evaluated carefully.

Special attention should be directed to the tuberosity region where bony and fibrous hypertrophy frequently result in contact between the residual ridge and the mandibular teeth, or perhaps between the two endentulous ridges.

Interridge space in the incisor region may be nonexistent as a result of extrusion of the mandibular incisors into contact with the palatal mucosa when the teeth are in occlusion

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INTEROCCLUSAL SPACE

The space between the occlusal and incisal surfaces of certain key teeth is crucially important.

Areas of the abutment teeth that are destined to accommodate occlusal, lingual, or incisal rests should be examined critically in order to assess the amount of space that is available and to estimate the additional space that must be provided.

When a lingual rest is required on a maxillary anterior tooth, the articulated study casts make it possible to view the lingual surface of the tooth involved with all the teeth in centric occlusion so that the precise amount of space available for the contemplated rest can be determined accurately.

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CAST ANALYSIS – ON THE SURVEYOR

The path of insertion as well as the design of the prosthesis will be established with the cast on the surveyor, so that all subsequent treatment can be based on this design.

SURVEYING THE DIAGNOSTIC CASTSurveying the diagnostic case is essential to effective diagnosis and treatment planning. The objectives are as follows:

1. To determine the most desirable path of placement that will eliminate or minimize interference to placement and removal.

2. To identify proximal tooth surfaces that are or need to be made parallel so that they act as guiding places during placement and removal.

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3. To locate and measure areas of the teeth that maybe used for retention.

4. To determine whether tooth and bony areas of interference will need to be eliminated surgically or by selecting a different path of placement.

5. To determine the most suitable path of placement that will permit locating retainers and artificial teeth to the esthetic advantages.

6. To permit an accurate charting of the mouth preparations to be made. This includes the preparation of proximal tooth surfaces to provide guiding planes and the reduction of excessive tooth contours to eliminate interference and to permit a more acceptable location of reciprocal and retentive clasp arms.

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7. To delineate the height of contour on abutment teeth and to locate areas of undesirable tooth undercut that are to be avoided, eliminated, or blocked out.

8. To record the cast position in relation to the selected path of placement for future reference.

INTERPRETATION OF EXAMINATION DATA

As a result of the oral examination and diagnosis, certain data should be recorded, much of which are based on decisions that are the result of the diagnosis and reflect the patient’s present and predictable health status.

The quality of the alveolar support of an abutment tooth is of primary importance because the tooth will have to withstand greater stress loads when supporting a dental prosthesis.

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Abutment teeth providing total abutment support to the prosthesis,

be it either fixed or removable, will have to withstand a greater

load and especially greater horizontal forces.

Abutment teeth adjacent to distal extension bases are subjected not

only to vertical and horizontal forces but to torque as well because

of the movement of the tissue-supported base.

Each abutment tooth must be evaluated carefully as to the alveolar

bone support present and the past reaction of that bone to occlusal

stress.

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Index areas

Index areas are those areas of alveolar support that disclose the reaction of bone to additional stress. Favourable reaction to such stress may be taken as an indication of future reaction to an added stress load.

The patient is said to have a positive bone factor, which means the ability to build additional support wherever needed.

Other index areas are those around teeth that have been subjected to abnormal occlusal loading; that have been subjected to diagonal occlusal loading caused by tooth migration; and that have reacted to additional loading, such as around existing fixed partial denture abutments.

The patient is said to have a negative bone factor, which means the inability to respond favorably to stress.

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Alveolar lamina dura

The alveolar lamina dura is also considered in a radiographic interpreation of abutment teeth.

The lamina dura is the thin layer of hard cortical bone that normally lines the sockets of all cortical bone, its function is to withstand mechanical strain.

In a radiograph the lamina dura is shown as a radiopaque white line around the radiolucent dark line that represents the periodontal membrane.

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Root morphology

The morphologic characteristics of the roots determine to a great extent the ability of prospective abutment teeth to resist successfully additional rotational forces that may be placed on them.

Teeth with multiple and divergent roots will resist stresses better than teeth with fused and conical roots, since the resultant forces distributed through a greater number of periodontal fibers to a larger amount of supporting bone.

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Third molars

Unerupted third molars should be considered as prospective future abutments to eliminate the need for a distal extension removable partial denture.

The increased stability of a tooth-supported denture is most desirable to enhance the health of the oral environment.

Periodontal considerations

An assessment of the periodontium in general and abutment teeth in particular must be made before prosthetic reconstruction.

One must evaluate the condition of the gingiva, looking for adequate zones of attached gingival and the presence absence of pockets.

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The condition of the supporting bone must be evaluated and mobility patterns recorded.

If mucogingival involvements, osseous defects, or mobility patterns are recorded, the causes and potential treatment must be determined.

Oral hygiene habits of the patient must be determined, and efforts made to educate the patient relative to plaque control.

Additionally, the patient must be advised of the importance of regular maintenance appointments after reconstruction.

The remaining teeth will require meticulous plaque control after placement of a removable partial denture.

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Caries activity

Caries activity in the mouth, past and present, and the need for protective restorations must be considered.

The decision to use full coverage is based on the age of the patient, evidence of caries activity, and the patient’s oral hygiene habits.

Occasionally three-quarter crowns may as used where buccal or lingual surfaces are completely sound, but intracoronal restorations (inlays) seldom indicated in any mouth with evidence of past extensive caries or pre-carious areas of decalcification, erosion, or exposed cementum.

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Prospective Surgical Preparation

Need for Surgery or extractions must be evaluated.

The same criteria apply to surgical intervention in the partially edentulous arch as in the completely edentulous arch.

Grossly displaceable soft tissues covering basal seat areas and hyperplastic tissue should be removed to provide a firm denture foundation.

Mandibular tori should be removed if they will interfere with the optimum location of a lingual bar connector or a favorable path of placement.

Any other areas of bone prominence that will interfere with the path of placement should also be removed.

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The path of placement will be dictated primarily by the guiding plane of the abutment teeth.

Therefore some areas may present interference to the path of placement of the partial denture by reason of the fact that other unalterable factors such as retention and esthetics must take precedence in selecting that path.

Extraction of teeth may be indicated for one of the following three reasons.

1. If the tooth cannot be restored to a state of health, extraction may be unavoidable.

2. A tooth may be removed if its absence will permit a more serviceable and less complicated partial denture design.

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Teeth in extreme mal position (lingually inclined mandibular teeth, and mesially inclined teeth posterior to an edentulous space) may be removed if an adjacent tooth is in good alignment and if good support is available for use as an abutment.

3. A tooth may be extracted if it is so unesthetically located as to justify its removal to improve appearance.

Need for reshaping remaining teeth

Many failures of partial dentures can be attributed to the fact that the teeth were not reshaped property to establish guiding planes or to receive clasp arms and occlusal rests before the impression for the master cast was made.

Of particular importance are the paralleling of proximal tooth surfaces to act as guiding planes, the preparation of adequate rest areas, and the reduction of unfavorable tooth contours.

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To neglect planning such mouth preparations in advance is inexcusable.

The design of clasps is dependent on the location of the retentive, stabilizing, reciprocal, and supporting areas in relation to a definite path of placement and removal.

Failure to reshape unfavorably inclined tooth surfaces and, if necessary, to place restorations with suitable contours not only complicates the design and location of clasp retainers but also frequently leads to failure of the partial denture because of poor clasp design.

A malaligned tooth or one that is inclined unfavorably may make it necessary to place certain parts of the clasp so that they interfere with the opposing teeth.

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Unparallel proximal tooth surfaces not only will fail to provide needed guiding planes during placement and removal but also will result in excessive blockout.

This inevitably results in the connectors places so far out of contact with tooth surfaces that food traps are created.

To pass lingually inclined lower teeth, clearance for a lingual bar major connector may have to be so great that a food trap will result when the restoration is fully seated, and the lingual bar will be located so that it will interfere with tongue comfort and function.

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Reduction of unfavorable tooth contours

Reduction of unfavorable tooth contours will greatly facilitate the design of the partial denture framework.

The need for modification of tooth contours must be established during the diagnosis and treatment planning phase of partial denture service.

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DIAGNOSTIC WAX-UP

A diagnostic wax-up is a valuable diagnostic tool, especially if multiple crowns or fixed partial dentures need to be constructed in conjunction with a removable partial denture.

Problems involving the position and relationship of the remaining teeth become apparent.

The diagnostic wax-up provides a guide for tooth preparation and helps indicate problems that may be encountered in positioning cusps and in establishing acceptable occlusal contacts.

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SUMMARY

An RPD is the restoration of choice under the following conditions.

1. When there are no posterior terminal abutment teeth present, so that a distal – extension base is required to support the prosthesis.

2. When the edentulous spaces are too extensive or too curved to be successfully restored with tan FPD (Zarb & MacKay, 1981).

3. When there is a need to provide replacement for missing hard and soft tissues with an acrylic resin denture base in order to restore normal tissue contours and lip support.

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4. When the cross-arch splinting provided by an RPD will be helpful in supporting and preserving periodontially weakened teeth.

5. When it is anticipated that additional teeth will be lost sometime after the fabrication of the prosthesis.

Additional denture teeth may be added to an RPD that has been designed with this contingency in mind.

A tooth- supported RPD may even be converted to a distal – extension RPD by the addition of a denture tooth and an appropriate denture base.

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BIBLIOGRAPHY

1. McCracken’s – Removable Partial Prosthodontics

2. Renner & Boucher – Removable Partial Dentures

3. Stewart – Clinical Removable Partial Prosthodontics

4. A Roy MacGregor – Removable Partial Prosthodontics

5. Grasso & Miller – Removable Partial Prosthodontics

6. GPT–7