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Diagnosis and treatment
 

Diagnosis and treatment

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    Diagnosis and treatment Diagnosis and treatment Document Transcript

    • DIAGNOSIS AND TREATMENT PLANNING FOR REMOVABLE PARTIAL DENTURES Introduction 1) The restoration of partially edentulous mouth presents the challenge to re-establish masticatory efficiency, esthetics and comfort in a manner which will promote and perpetuate oral health. 2) As the remaining teeth and edentulous ridges have to sustain greater stress than that intended by nature, the preservation of these tissues is one of the permanent objectives. 3) Many of the dentures which are planned to give lengthy service become temporary appliances because important biomechanical factors were ignored during planning. 4) If the relationship between the biologic behaviour of the oral structures and the mechanical influence of the denture is not recognized, the denture often contribute towards rapid disintegration of tissues. 5) A successful partial denture cannot be produced by the skillful application of technique alone. It must be conceived and 1
    • constructed upon the knowledge of oral and dental anatomy, biology, histology, pathology, physics and their allied sciences if the oral tissues are to be preserved. 6) Before any rehabilitation procedures are attempted, pertinent information must be gathered to provide the evidence necessary to arrive at an accurate diagnosis and develop a round treatment plan. OBJECTIVES OF PROSTHODONTIC TREATMENT i) Elimination of disease ιι) → ιιι) → Patients who seek treatment are only concerned with replacement of missing teeth. The dentists primary obligation to the patient is to emphasize the importance of restoring the mouth to a total state of health. The extent to which lost function can be restored depends on tissue tolerance of the individual, as influenced by age, general health and health of oral tissues. 2
    • In order to fulfill these objectives, the diagnosis and treatment planning should follow a particular sequence. ORAL EXAMINATION It should be complete and include, - Visual and digital examination of teeth and surrounding tissues. - Examination with mouth mirror, explorer and a periodontal probe. - A complete intraoral roentgenographic survey. - Vitality test of critical teeth. - Examination of casts correctly oriented on an adjustable articulator. Sequence of oral examination 1. Visual examination: It 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. Only those patients who demonstrate good oral hygiene and low caries susceptibility may be considered as good risks for partial 3
    • denture treatment. Otherwise prophylactic measures such as crowning of abutment teeth have to be though of evidence of periodontal disease, inflammation of gingival areas and degree of gingival recession should be observed. Depths of periodontal pockets should be determined and teeth mobility by digital examination. One should keep in mind that the extent of damage to the supporting structures by periodontal disease can exactly be determined only by roentgenographic interpretation. The number of teeth remaining, the location of edentulous areas and the quality of residual ridge will have a definite bearing on the proportionate amount of support that the partial denture will receive from teeth and edentulous areas. Palpation can indicate the nature of supporting bone that has been resorbed and replaced by displaceable fibrous connective tissue. This is common in maxillary tuberosity regions. Removable partial dentures cannot be supported adequately by tissue that are easily displaced. These tissues must be treated non surgically or surgically. The presence of tori or other exostoses must be detected. The difference in displaceability of soft tissues covering midpalatal 4
    • raphae and soft tissues covering residual ridges must be determined. If not it will lead to a rocking, unstable uncomfortable denture. Adequate relief of palatal major connectors must be planned. 2. Relief of pain and discomfort and placement of temporary restorations. It is advisable not only to relieve discomfort arising from tooth defects but also to determine as early as possible the extent of caries and to arrest further caries activity until definite treatment can be instituted. By restoring tooth contours with temporary restorations, the impression will not be torn on removal from the mouth and a more accurate diagnostic cast may be obtained. 3. Complete intraoral roentgenographic survey The objectives of roentgenographic examinations are: a) To locate areas of infection and other pathoses. b) c) d) 5
    • 4. A thorough and complete oral prophylaxis An adequate examination can be accomplished best with the teeth free of accumulated calculus and debris. Accurate diagnostic casts can also be obtained only if the teeth are clean. Cursory examination may precede an oral prophylaxis, but a complete oral examination should be deferred until the teeth have been thoroughly cleaned. 5. Exploration of teeth and investing structures They are explored by instruments and digital examination. Occlusal relationships and tooth mobility have to be determined. A situation that looks simple when the teeth are apart may be complicated when the teeth are in occlusion. E.g.: extrusion of a tooth or teeth into an opposing edentulous area may complicate the replacement of teeth in the edentulous area or it may create cuspal interference. History and diagnostic charts should be filled out at this time. 6
    • 6. Vitality tests of remaining teeth It should be carried out particularly on teeth to be used as abutments and on those having deep restorations or deep carious lesions. This may be done either by thermal or electrical means. DIAGNOSTIC CASTS It should be an accurate reproduction of the teeth and adjacent tissues. The impression for the diagnostic cast is usually made with an irreversible hydrocolloid in a perforated impression tray. The diagnostic cast should be made of dental stone because of its strength and the fact that it is less easily abraded than dental plaster. Mounting Diagnostic Casts Although some diagnostic casts may be occluded by hard, occlusal analysis is much better accomplished when casts are mounted on a semiadjustable or adjustable articulator. The casts have to be mounted in relation to the axis orbital plane to interpret plane of occlusion in relation to horizontal plane. The facebow is a relatively simple device used for orienting the maxilla. The 7
    • addition of an adjustable infraorbital pointer on the facebow and the addition of an orbital plane indicator to the articulator makes possible the transfer of cast in relation to axis orbital plane. This permits to orient the maxillary cast on the articulator in the same comfortable relationship of the maxilla to the Frankfort plane on the patient. A facebow used to transfer the arbitrary hinge axis is termed the arbitrary face bow and the one used to transfer true hinge axis is termed kinematic face bow. An occlusal rim has to be used in face-bow transfer procedures involving Class I and II partially edentulous situations. Jaw relationship records for diagnostic casts One of the first critical decisions to be made in a removable partial denture service involves the selection of horizontal jaw relationship (centric relation or maximum intercuspal position). All mouth preparation procedures depend on this relationship. If most natural posterior teeth remain and there is no evidence of TMJ disturbances, neuromuscular dysfunction or deflective occlusal contacts, the proposed restoration may safely be fabricated with maximum intercuspation of remaining teeth. 8
    • When most of the natural centric stops (posterior teeth) are missing, the restoration should be fabricated so that maximum intercuspal position is in harmony with centric relation. The centric relation position is recorded by the use of an interocclusal medium without bringing the teeth into contact. Tooth contact is not allowed because malaligned teeth or interfering cusps tend to guide the mandible out of centric relation, displacing the heads of the condyles from their proper positions in the glenoid fossae. Purposes of diagnostic casts 1. They are used to supplement oral examination by permitting a view of the occlusion from lingual as well as buccal aspect. The degree of overclosure, the amount of interocclusal space needed and the possibilities of interference to location of rests may also be noted sometimes, the mandibular anterior teeth are on a higher plane compared to mandibular posterior teeth. This is a disturbing condition and a destructive process is unavoidable with advancing age. In some caries, an increase in vertical height of lower posterior teeth can be induced by placing an occlusal splint in the palate with occlusal contact available only in the anterior area. Good results are obtained by constantly wearing such an appliance over a limited period of time. These patients must be 9
    • followed carefully to establish the correct intercuspation of opposing teeth. 2. Harmonious occlusal plane and curve of spee The loss of one or more teeth without immediate replacement results in loss of contact between the approximating teeth within the arch and an elongation of teeth in the opposing arch. Treatment planning in such cases is complicated by a lack of harmony of the curve of spee and occlusal plane with the path of movement of the TMJ. The path of movement of the condyle is fixed whereas the cusp rise in the anterior part of the segment can be reconstructed by the dentist to aid in establishing a harmonious intercuspation of the posterior teeth. The procedure is to have the study casts mounted on an adjustable articulator with correct condylar settings for both centric and eccentric functional positions. Then with inlay wax, build the teeth of the study casts to the contour that will produce balanced occlusion throughout functional excursions. The dentist can then determine the teeth that will need a decrease or an increase in vertical dimension and cusp rise necessary to create a curve of spee and a plane of occlusion for posterior quadrants. 10
    • 3. Diagnostic casts permit a topographic survey of the dental arch that is to be restored by means of a removable partial denture. The cast in question may be surveyed to determine the parallelism or lack of parallelism of tooth surfaces involved to establish their influence on the design of the partial denture. The need to study parallelism of tooth and tissue surface of each dental arch is to determine. a) Proximal tooth surfaces which can be made parallel to serve as guiding planes. b) Retentive and non-retentive areas of abutment teeth. c) Areas of interference to placement and removal from such a survey a path of placement may be selected that will satisfy the requirements of parallelism and retention to the best mechanical, functional and esthetic advantage. 4. Diagnostic casts can be used to make the patient understand regarding the present and future restorative needs. Occluded or individual diagnostic casts can be used to point out: a) Evidence of tooth migration, b) effects of further tooth migration, c) Hazards of traumatic occlusal contacts. 11
    • 5. Diagnostic casts may be used as a constant reference as the work progress. Penicilled marks indicating the type of restorations. The areas of tooth surfaces to be modified, the location of rests and the design of partial denture framework, as well as path of placement and removal, all may be recorded on the diagnostic cast. 6. Individual impression trays may be fabricated on diagnostic casts for making final impression. This is fabricated on the duplicate diagnostic cast after wax blockout. INTERPRETATION OF EXAMINATION DATA Roentgenographic interpretation Radiographic interpretation most pertinent to partial denture construction are those relative to prognosis of remaining teeth that may be used as abutments. The quality of the alveolar support of an abutment tooth is of prime importance because the tooth will have to withstand greater stress loads when supporting a dental prosthesis, 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. 12
    • Value of interpreting bone density The quality and quantity of bone in any part of the body is often evaluated by roentgenographic means. It is essential to emphasize that changes in bone calcification upto 25-30% cannot be recognized by ordinary roentgenographic means. So the dentist should realize that roentgenographic evidence shows the results of changes that have taken place and may not necessarily represent the present condition. Normally the interradicular trabecular spaces usually tend to decrease in size as the examination of bone is proceeded from root apex towards coronal portion. The normal interproximal crest is ordinarily shown by a thin white line crossing from lamina dura of one tooth to the adjacent tooth. Normal bone usually responds favourably to ordinary stresses. Abnormal stresses may create a reduction in the size of the trabecular pattern particularly in that area of bone directly adjacent to the lamina dura of affected tooth. This decrease in size of the trabecular pattern is regarded as bone-condensation which is an improvement in bone quality. 13
    • An increased thickness of periodontal space ordinarily suggests varying degrees of tooth mobility. Such teeth have to be evaluated clinically. X-ray evidence plus clinical findings may suggest the inadvisability of using such a tooth as an abutment. Rounding off of the intercrestal bone is the first evidence of periodontal disease. The level of the bony crest is considered normal when it is within 1.5mm from the CEJ of the adjacent teeth. Teeth that have been subjected to abnormal bonding because of loss of adjacent teeth or teeth that have withstand tipping forces in addition to occlusal loading may be better risks as abutment teeth than those that have not been called on to carry an extra occlusal load. If occlusal harmony can be improved and unfavourable forces minimized such teeth may be expected to support the prosthesis without difficulty. The reaction of bone to additional stresses may be positive or negative. A positive response is indicated by a heavy trabecular pattern and dense lamina dura. Negative response is the reverse. Root morphology: Morphologic characteristics of the roots determine to a great extent to ability of the 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 are distributed through 14
    • a greater number of periodontal fibres to a larger amount of supporting bone. PERIODONTAL CONSIDERATIONS One must evaluate the condition of the gingiva, looking for adequate zones of attached gingiva as well as presence or absence of pockets. If mucogingival involvements, osseous defects or mobility patterns are recorded, the causes and potential treatment must be determined. Oral hygiene habits: Efforts must be made to educate the patient relative to plaque control. The patient must be advised of importance of regular maintenance appointments after reconstruction. Caries activity: The past and present caries activity must be determined and need for protective restorations may be considered. The decision to use full coverage is based on the age of the patient, evidence of caries activity and patient’s oral hygiene habits. High and frequent consumption of sugars can lead to root caries, caries around restorations or clasps of partial dentures. Excellent protection from caries can be provided by fluoride applications. 15
    • Need for surgery or extractions: Grossly displaceable soft tissues covering basal seat and hyperplastic tissues should be removed to provide a firm denture foundation. Mandibular tori should be removed if they will interfere with optimum location of lingual bar connector or a favourable path of placement. Extraction of teeth may be indicated for one of the following reasons. 1) If the tooth cannot be restored to a state of health. 2) Teeth in extreme malposition may be removed. An exception to the removal of a malposed tooth would be when a distal extension basal have to be made rather than a more desirable tooth supported base. If alveolar support is adequate, a posterior tooth should be retained. 3) A tooth should be extracted if it is unesthetically located and if the extraction of the same would improve appearance. 16
    • DIFFERENTIAL DIAGNOSIS : FIXED OR REMOVABLE PARTIALD ENTURES Indications for fixed restorations 1) Tooth bound edentulous regions: Any edentulous space (short span) bounded by teeth suitable for use as abutments should be restored with a fixed partial denture. 2) Additional modification spaces in Class III modification 1 situation: A removable partial denture is better supported and stabilized when a modification area on the opposite side of the arch is present such an edentulous area need not be restored by a fixed dentures. Additional modification spaces particularly those involving single missing teeth are better restored separately by means of fixed dentures. By doing so the denture is made less complicated by not having to include other abutment teeth for support and retention. The teeter-tetter effect of the denture is also avoided. When an edentulous space exists anterior to a bone-standing abutment tooth, this tooth is subjected to trauma by movements of distal extension partial denture far in excess of its ability to withstand such 17
    • stresses. The splinting of the line abutment to the nearest tooth is mandatory. Splinting is best accomplished in such a situation by means of a fixed partial denture uniting two teeth on either side of the edentulous space. The abutment crowns should be contoured for retention and support of the partial denture. Indications for removable partial dentures Although a removable partial denture should be considered only when a fixed restoration is contraindicated, there are several specific indications for the use of a removable restoration. 1) Long span: A long edentulous span would have abutment teeth which cannot bear the trauma of horizontal and diagonal occlusal forces. Also because of ridge resorption, the pontics may have to be placed in extreme labial inclination for lip support. In such cases a removable partial denture which provides favourable esthetics and cross arch stabilization is indicated. 2) Need for effect of bilateral stabilization: In a mouth weakened by periodontal disease, a fixed restoration may jeopardize the future of involved abutment teeth. The removable partial denture on the other hand may act as a periodontal splint through its effective cross-arch stabilization of teeth weakened by periodontal disease. 18
    • 3) Excessive loss of bone in posterior area: The pontic of a fixed partial denture must be related to the residual ridge in such a manner that the occlusal contact with the mucosa is gentle. Whenever excessive resorption has occurred, teeth supported by a denture base may be arranged in a more acceptable bucco-lingual position than is possible with a fixed partial denture. 4) Where a future change in denture design is anticipated: If the prognosis of an abutment tooth is questionable or if it becomes unfavourable while under treatment. It might be possible to compensate for its impending loss by a change in denture design. 5) Distal extension caries. CHOICE BETWEEN COMPLETE DENTURE AND REMOVABLE PARTIAL DENTURE The loss of remaining teeth can be terrible psychologic shock to patients. The dentist should explore every possibility of saving them. 1) In most instances it may be more desirable for the patient to retain loose or broken teeth. In other patients it may be that their health can be improved if remaining teeth are removed. 19
    • 2) The age of the patient can be a factor. If the patient is young and bone is not fully calcified, the remaining teeth should probably be saved. 3) Limitations of maxillary removable partial denture : when adequate interridge space and sufficient number of healthy natural teeth are available in strategic-locations, the prognosis for a removable partial denture is highly favourable. These conditions are not always present.  Interridge space is reduced by mandibular teeth which have extended above the plane of occlusion.  An increase in vertical dimension is not possible as it has not been altered.  If the remaining maxillary teeth are extracted, biomechanical problem is created by distal extension bases. Gravity magnified by leverage becomes a major antiretentive factor.  The crown contours of max canines do not provide undercuts for clasp retention and lingual surfaces are not suitable for rest preparation, space for rest on lingual surface is lacking because of opposing mandibular teeth (deep bite). 20
    •  Crowning of the tooth to create a usable retentive undercut and to provide cingulum rest requires a labial veneer for cosmatic reasons (Adds to the cost of restorations).  If maxillary canines must be used as abutments, a clasp arm and denture flange are often prominently displayed at the corner of the mouth. MAXILLARY COMPLETE DENTURES have many advantages over removable partial dentures in such a situation.  Centric occlusion and centric relation can be made to coincide at proper vertical relation.  A deep vertical overlap of anterior teeth can be reduced and a horizontal overlap modified.  Unesthetic appearance of clasp arms and denture flanges can be avoided.  Need to grind natural teeth to create rest seats is eliminated.  Thus prognosis is improved for all remaining teeth and supporting bone. 21